Дисертації з теми "Availability Modeling"
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1
Krishnamurthy, Ganesh. "Incorporating salinity considerations in water availability modeling." Texas A&M University, 2006. http://hdl.handle.net/1969.1/3833.
Анотація:
This research focused on expanding the capabilities of the Water Rights Analysis
Package (WRAP) for incorporating salinity considerations in assessments of water
availability. A simulation modeling approach was used to address this issue and a
generalized simulation model called WRAP-SALT was developed. The Brazos River
Basin served as a case study to test the simulation approach adopted by the model.
The simulation model adopts a generalized modeling approach applicable to any
river basin system. The model tracks salinity throughout a river basin system over
different periods of time for alternative scenarios of water use, reservoir system
operating policies, and salt control mechanisms. The model was applied to the Brazos
River Basin considering different management scenarios and the results obtained were
analyzed.
Reservoir reliabilities were assessed under user imposed salinity constraints. It
was observed that the water supply reliabilities decreased significantly if salinity
constraints were considered. Salt control dams proposed by the U.S. Army Corps of Engineers were also incorporated in the simulation of the river basin. It was observed
that salinity in the main stem of the Brazos River was significantly reduced. However,
no significant improvement was observed in water supply reliabilities.
2
Schuol, Jürgen. "GIS-based hydrological modeling of freshwater availability in Africa /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17491.
3
French, Timothy F. "Comparison of operational availability modeling by TIGER and SESAME." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283943.
Анотація:
Thesis (M.S. in Operations Research) Naval Postgraduate School, June 1994.Thesis advisor(s): Alan W. McMasters, James D. Esary. "June 1994." Includes bibliographical references. Also available online.
4
Duan, Chunming. "Stochastic availability analysis and modeling of longwall mining operations." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07122007-103924/.
5
Amich, Amine. "Efficient spectrum utilization using statistical modeling of channel availability." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/807095/.
Анотація:
Cognitive radio systems have been suggested as a method to improve spectrum utilization by detecting and accessing vacant spectrum. In such a network, sub-bands of a spectrum are shared by licensed (primary) and unlicensed (secondary) users in that preferential order. It is generally recognized that the spectral occupancy by primary users exhibit dynamical spatial and temporal properties and hence the fundamental issue is to characterize the sub-band spectrum occupancy in terms of probabilities. Given statistical analysis of the frequency band of interest are available, it has been shown that adaptive searching for white spaces could improve by 70% when compared to random searching. In the open literature, there exist no accurate/efficient time-varying model representing the spectrum occupancy that the wireless researchers could employ for evaluating new algorithms and techniques designed for dynamic spectrum access (DSA). Therefore, the objective is to propose an accurate and efficient analytic model that can be used to enhance the sensing operations. Using real-time measurements conducted in different geographic locations, existing research has validated that subchannel availability is suitably modeled as independent but non identical (i.n.i.d.) Bernoulli variables characterized by pi , the probability of availability of the i-th subchannel. The magnitude of pi ’s could be extracted from sensed measurements or a geolocation database. Based on the i.n.i.d. paradigm, we develop a predictive model by probabilistically computing the distribution of the number of available subchannels over a wide-band at a given time. However, the combinatorial complexity behind the exact distribution computation alludes the need for accurate and efficient alternative approaches that can support frequency bands with a large number of non-overlapping subchannels. We propose 3 different techniques based on convolution, recursive, and hybrid convolution-recursive methods to resolve this complexity. We assess their efficiency by analyzing each algorithm’s time complexity and further compare their performance against existing models in the literature. Moreover, knowing the availability of the channel’s immediate neighbors can allow efficient power management as well as prioritize channels allocation to secondary users. Therefore, we categorize available channels into three different types based on the occupancy of its two adjacent channels then model their availability. Additionally, from a network performance analysis perspective, predicting the count of available channels has to be evaluated against the probability of detecting these channels within the same i.n.i.d. framework. Respectively, we propose a novel approach to calculate the probability of detecting multi-channels simultaneously. Finally, we validate the effectiveness of the proposed models using several real-time measurements and further present 2 associated applications where one features novel 2-Dimensional (time, freq) availability prediction.
6
Pinheiro, Everton Alves Rodrigues. "Hydrological modeling of soil-water availability in the Caatinga biome." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11152/tde-10112016-170843/.
Анотація:
Northeastern Brazil is hydrologically characterized by recurrent droughts leading to a highly vulnerable natural water resource system. The region contains the Caatinga biome, a sparsely studied ecosystem, covering an area of approximately 800,000 km2. Reduced wateravailability is projected to take place in large regions of the globe, including Northeastern Brazil. Given the strong interactions between climate and vegetation, research has addressed climate change effects on natural and agricultural ecosystems. In this context, soil hydraulic properties are essential to assess soil water flow, and thus the ability of soil to supply water to plants at potential rates under different ranges of pressure head. Based on that, the aims of this thesis are: to increase insight in water balance components for the Caatinga biome, under current and future climate scenarios; and to assess the ability of soils in supplying water to plants by the further development of an existing matric flux potential approach, followed by its application to a group of soils from two Brazilian climatic zones (semi-arid and subhumid). Both for current and future climate scenarios, hydrological simulations were performed with SWAP model parameterized for a preserved Caatinga basin of 12 km2. The validation of the simulations was performed using a dataset of daily soil-water content measurements taken at 0.2 m depth in the period from 2004 to 2012. The soil water supplying capacity was evaluated through a multilayer matric flux potential approach, coupling the soil hydraulic properties, root length density and plant transpiration. Regarding the current climate conditions, the Caatinga biome returns 75% of the annual precipitation to the atmosphere, whereas the partitioning of total evapotranspiration into its components (transpiration, evaporation and interception) on annual basis accounts for 41%, 40% and 19%, respectively. Evapotranspiration and air temperature are most sensitive to soil moisture during the periods June-September and December-January. Concerning the future climate, transpiration was enhanced by 36%, soil evaporation and interception losses reduced by 16% and 34%, respectively. The amount of precipitation returned to the atmosphere was on average 98%. For both climate scenarios, the soil-plant-atmosphere fluxes seem to be controlled by the surface soil layer (0-0.2 m) which provides, on average, 80% of the total transpiration, suggesting that the Caatinga biome may become completely soil-water pulse dominated under scenarios of reduced water availability. The matric flux potential analysis revealed that soils from the semiarid zone were able to deliver water to plants at potential rates under a wider range of bulk soil pressure head (-36 to -148 m), whereas the soils from the wetter zone showed more hydraulic restriction with limiting soil water potential above -1.5 m. For the analyzed soils, only a negligible increase in available water results from decreasing the root water potential below -150 m, therefore, in order to adapt to water-limited conditions, plant species may invest in other adaptive strategies, rather than spending energy in structures that allow a reduction of the lower suction limit in their tissues.O Nordeste do Brasil é hidrologicamente caracterizado por secas recorrentes, tornando os recursos hídricos naturais altamente vulneráveis. Nesta região está o bioma Caatinga, ocupando uma área de aproximadamente 800.000 km2. Cenários de déficit hídrico são projetados para grandes regiões do globo, incluindo o Nordeste brasileiro. Devido às interações entre clima e vegetação, várias pesquisas têm abordado os efeitos das mudanças climáticas sobre os ecossistemas naturais e agrícolas. Neste contexto, as propriedades hidráulicas do solo são essenciais para avaliar o movimento de água, e assim a capacidade de fornecimento de água às plantas. Com base nesta contextualização, os objetivos desta tese são: simular os componentes do balanço hídrico do bioma Caatinga para cenários climáticos atuais e futuros; e avaliar a capacidade de alguns solos em fornecer água às plantas a partir de uma abordagem de potencial de fluxo matricial. Para os cenários climáticos atuais e futuros, simulações hidrológicas foram realizadas com o modelo SWAP, parametrizado para uma microbacia de 12 km2, inserida em área de Caatinga preservada. A validação das simulações foi processada a partir de medidas diárias do conteúdo de água do solo na profundidade de 0,2 m no período de 2004 a 2012. A capacidade do solo em fornecer água às plantas foi avaliada através da atualização de uma função de potencial de fluxo matricial, que acopla as propriedades hidráulicas do solo, densidade de comprimento radicular e transpiração das plantas, aplicada a um grupo de solos da zona climática semiárida e sub-úmida. Como resultados principais destacam-se: nas condições climáticas atuais, o bioma Caatinga retorna 75% da precipitação anual para a atmosfera como evapotranspiração, particionada entre seus componentes (transpiração, evaporação e intercepção) em 41%, 40% e 19%, respectivamente. Evapotranspiração e temperatura do ar foram sensíveis à umidade do solo durante os períodos de junho-setembro e dezembro-janeiro. Em relação ao cenário climático futuro, a taxa de transpiração foi acrescida em 36%. A evaporação do solo e a interceptação foram reduzidas em 16% e 34%, respectivamente. A quantidade de precipitação devolvida para a atmosfera foi em média 98%. Para ambos os cenários climáticos, é sugerido que os fluxos de água no sistema solo-planta-atmosfera são controlados pela camada superior do solo (0-0,2 m), fornecendo, em média, 80% do total transpirado, indicando que, caso os cenários de disponibilidade hídrica reduzida se confirmem, o bioma Caatinga pode se tornar completamente dependente dos pulsos de água no solo. A partir do potencial de fluxo matricial limitante revelou-se que os solos da região semiárida são capazes de manter o fluxo de água às plantas em taxas potenciais em condições de solo seco (potencial matricial limitante variando de -36 a -148 m), enquanto que, os solos da região mais úmida indicaram severa restrição hidráulica, com potencial matricial limitante maior do que -1,5 m. Ainda para os solos analisados, a atribuição de potencial na superfície da raiz inferior a -150 m não ocasionou aumento de disponibilidade hídrica, indicando que valores menores que -150 m não implicam em uma estratégia viável para suportar baixa disponibilidade hídrica.
7
Olmos, Alejo Hector Elias. "Improving capabilities for dealing with key complexities of water availability modeling." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1463.
Анотація:
Water availability has been of great concern in the State of Texas and many other places worldwide. During 1997-2003, pursuant to the 1997 Senate Bill 1, the Texas
Commission on Environmental Quality (TCEQ), its partner agencies, and contractors
developed a Water Availability Modeling (WAM) System based on the Water Rights
Analysis Package (WRAP) model, developed at Texas A&M University. WAM has been
widely applied in the State of Texas and because of its convenience, applications, and
capabilities, it is planned to be implemented in other States and Countries.
This thesis addresses different aspects of WAM, including conditional reliability
modeling, firm yield analysis following classic and recently developed methodologies,
evaluating the impact of different considerations on reliability analyses, simplification of
complex WAM datasets and the display of WRAP results into ArcMap.
Conditional reliability modeling evaluates short term diversion/storage
reliabilities based on an initial storage level. WRAP-CON has been evaluated and
improved, in addition a new modeling methodology has been developed, in which
probabilities of occurrence for each hydrologic sequence is based on the relationship
between storage and future flows.
Recently developed WRAP capabilities have been evaluated, providing users
new tools and increased flexibility. Some of these improvements are firm yield analysis,
cycling and dual simulation.
In addition to improved software, guidelines have also been developed,
including a set to simplify extremely large WAM datasets, while maintaining the effect of
all the other water rights in a basin.
8
Thorn, Dustin, and Matt Hubbard. "Investigating the relationship between customer wait time and operational availability through simulation modeling." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/27914.
Анотація:
Customer Wait Time (CWT) measures all supply chain processes, from the time a customer places an order until the item is delivered. The Marine Corps intermediate supply activity, the Supply Management Unit (SMU), has the primary task of reducing the amount of time it takes for the operating forces to receive supplies by stocking items close to the warfighter. Such forward positioning of repair parts shields the operating forces from delays found at the wholesale inventory level, thereby increasing the material readiness of the operating forces. Intuitively, decreasing CWT increases operational availability (Ao), but the degree and magnitude of this relationship has yet to be quantified. This lack of understanding pertaining to the relationship between Ao and CWT has led to arbitrary stock policies that do not account for the cost and benefit they provide. This project centers on monetizing the relationship between these variables through simulation modeling, and provides a tool whereby stock determination can be made based on desired end states.
9
Feng, Xin. "In vivo and modeling approaches to improve prediction of phosphorus availability in ruminants." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/52910.
Анотація:
Improving prediction of P availability necessitates understanding of P digestion and absorption mechanism in ruminants. Greater knowledge of the interaction of P with other nutrients and the utilization of dietary P in the digestive tract will improve our ability to optimize P feeding and reduce P runoff in agricultural areas. In vivo experiments were performed and the data were used to reparamterize a model regarding P digestion and metabolism.
The interaction of P and iron was investigated in lactating dairy cows by infusing 0, 200, 500, or 1250 mg/d Fe (equivalent to 0, 2, 5, or 12.5 mg Fe/L in drinking water) in the form of ferrous lactate solution into the abomasum of lactating cows. Phosphorus absorption was not negatively influenced by abomasally infused ferrous lactate, and the highest infusion (1250 mg Fe/d) approximates a drinking water iron content far above that found in most samples from the field. In the second study the effects of dietary P intake on intestinal P absorption was evaluated in eight growing Holstein steers fitted with permanent duodenal and ileal cannulas. Diets varying in P content (0.15%, 0.27%, 0.36% and 0.45%, DM basis) were fed , and increasing P intake increased the quantity of P absorbed from the small intestine linearly without affecting the absorption efficiency (mean = 59.6%). Only a small portion of P absorption occurred in large intestine and this was not affected by dietary P concentration. An absence of change of salivary P secretion at low dietary P suggested rumen function was prioritized during short-term P deficiency.
Finally the data from these experiments along with four other studies were used to
parameterize the P digestion and metabolism model of Hill et al. (2008) to provide a better understanding of the digestion and metabolism of P fractions in cattle. The data used were adequate to parameterize the digestive elements of the model with good precision, and the model structure appears to be appropriate with no significant mean or slope bias. The resulting model could be used to derive P bio-availabilities of commonly used feedstuffs in cattle production. Although the model explained the data used with no apparent bias, this does not guarantee that the model parameters are valid for all conditions. Additional data are needed to evaluate this model in a wider range of scenarios.Ph. D.
10
McKim, Rebecca Lynn 1969. "Modeling changes in faunal use and availability on the Pajarito Plateau, New Mexico." Thesis, The University of Arizona, 1994. http://hdl.handle.net/10150/292002.
Анотація:
This thesis tests the hypothesis that resource depletion accompanied aggregation on the Pajarito Plateau. It does so by examining changes in faunal resource availability and resource use during the Coalition and early Classic periods. The prehistoric deer population was estimated using precipitation data, following Young (1979). This estimation was used as a measure of potential resource availability for the periods concerned. Based upon the model, the mule deer population was expected to increase from the Coalition period to the early Classic period. Resource use was measured using faunal assemblages from 10 sites from the Pajarito Plateau. The sites examined in this thesis support various expectations which would suggest that resource depletion occurred on the Pajarito Plateau. It was found that changes in resource use could not be explained by environmental change alone. Thus, it appears that resource depletion on the Pajarito Plateau may have been due to human impact on the environment.
11
Fu, Guobin. "Modeling water availability and its response to climatic change for the Spokane River Watershed." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Dissertations/Fall2005/g%5Ffu%5F120605.pdf.
12
Kyösti, Petter. "Modelling and simulation of support systems to predict operational availability." Licentiate thesis, Luleå tekniska universitet, Produkt- och produktionsutveckling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16993.
Анотація:
The aim of the work presented in this thesis is the development of the tools that support industry in offering FPs as a viable business case. A support system modelling and simulation tool, such as the one demonstrated in this thesis, would improve the possibilities of developing the support system early, concurrently with the development of the hardware. By performing a number of interviews and workshops, followed by a fault tree analysis to obtain the critical system components, a support system model was synthesised from the qualitative data. The model was translated into computer software designed in-house using C# to enable sufficient flexibility. Paper A demonstrates how collected data from interviews can be used to design a support system model to predict the behaviour of the support system. Paper B suggests how different parts of the FP model should be connected in terms of data flow to produce a system availability measurement. Paper C presents a modelling language for representing the details necessary to analyse and model the implementation of maintenance strategies for multi-component hardware. Some areas of refinement of the support system model are exemplified, such as travel distances and the occurrence of rare but harmful events.Godkänd; 2012; 20121005 (petkyo); LICENTIATSEMINARIUM Ämne: Datorstödd maskinkonstruktion/Computer Aided Design Examinator: Professor Lennart Karlsson, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Teknisk doktor Martin Helgoson, AB Sandvik Coromant Tid: Onsdag den 5 december 2012 kl 09.00 Plats: E231, Luleå tekniska universitet
Fastelaboratoriet - VINNEXC
13
Madrasi, Kumpal J. "Preservation of Nitric Oxide Availability as Nitrite and Nitrosothiols." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/805.
Анотація:
Nitric Oxide (NO) has been known for long to regulate vessel tone. However, the close proximity of the site of NO production to “sinks” of NO such as hemoglobin (Hb) in blood suggest that blood will scavenge most of the NO produced. Therefore, it is unclear how NO is able to play its physiological roles. The current study deals with means by which this could be understood. Towards studying the role of nitrosothiols and nitrite in preserving NO availability, a study of the kinetics of glutathione (GSH) nitrosation by NO donors in aerated buffered solutions was undertaken first. Results suggest an increase in the rate of the corresponding nitrosothiol (GSNO) formation with an increase in GSH with a half-maximum constant EC50 that depends on NO concentration, thus indicating a significant contribution of ∙NO2 mediated nitrosation in the production of GSNO. Next, the ability of nitrite to be reduced to NO in the smooth muscle cells was evaluated. The NO formed was inhibited by sGC inhibitors and accelerated by activators and was independent of O2 concentration. Nitrite transport mechanisms and effects of exogenous nitrate on transport and reduction of nitrite were examined. The results showed that sGC can mediate nitrite reduction to NO and nitrite is transported across the smooth muscle cell membrane via anion channels, both of which can be attenuated by nitrate. Finally, a 2 – D axisymmetric diffusion model was constructed to test the accumulation of NO in the smooth muscle layer from reduction of nitrite. It was observed that at the end of the simulation period with physiological concentrations of nitrite in the smooth muscle cells (SMC), a low sustained NO generated from nitrite reduction could maintain significant sGC activity and might affect vessel tone. The major nitrosating mechanism in the circulation at reduced O2 levels was found to be anaerobic and a Cu+ dependent GSNO reduction activity was found to deliver minor amounts of NO from physiological GSNO levels in the tissue.
14
Lopes, Josà Wellington Batista. "Hydrossedimentological modeling in semiarid meso-basin." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10890.
Анотація:
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoPractical problems related to water resources and the need for resolution of these was what drove the hydrological modeling, since understanding of the hydrological behavior of the basin was needed. So, this research was conducted to assess, through hydrossedimentological modeling, the behavior of a semiarid meso scale watershed as well as its water availability. The study area was the Madalena Representative Basin, Federal State of CearÃ, with 124kmÂ. Rainfall, accumulated volume and sedimentation in two reservoirs were monitored. The WASA-SED (Model of Water Availability in Semi-Arid Environments Sediment Dynamics with Component) and VYELAS (Volume-Yield Elasticity) models were used in the evaluation. Some conclusions could be obtained from the results: i) Continuous monitoring of hydrological variables in watersheds of the Brazilian semiarid is necessary because the scarcity of data makes it difficult to analyze the performance of hydrological models, ii) Sedimentation measurements in reservoirs is essential for validating of sedimentological routines of model for evaluation of long periods, iii) The soil parameters are determinant in the quality of the results and details of the parameterization significantly improves the performance of the WASA model, iv) The predominance of drought scenario for the next years must affect water supply due to the low volume currently accumulated in the reservoir, v) Water availability of the strategic reservoir of the basin (Marengo reservoir) in extreme years of low rainfall, for 90% reliability yield,is 96% lower than the availability expected for regular years.
Problemas prÃticos relacionados aos recursos hÃdricos e a necessidade de resoluÃÃo desses foi o que impulsionou a modelagem hidrolÃgica, pois uma melhor compreensÃo do comportamento hidrolÃgico da bacia hidrogrÃfica se fez necessÃria. Assim esta pesquisa foi conduzida com o objetivo de avaliar, por meio da modelagem hidrossedimentolÃgica, o comportamento de uma bacia hidrogrÃfica de meso-escala no semiÃrido, assim como sua disponibilidade hÃdrica. A Ãrea foco do estudo foi a Bacia Representativa de Madalena, CearÃ, com 124kmÂ. Os modelos WASA-SED (Model of Water Availability in Semi-Arid Environments with Sediment Dynamics Component) e VYELAS (Volume-Yield Elasticity) foram utilizados na avaliaÃÃo. Algumas conclusÃes puderam ser constatadas a partir dos resultados obtidos: i) O monitoramento contÃnuo das variÃveis hidrolÃgicas em bacias hidrogrÃficas do semiÃrido se faz necessÃrio, pois a insuficiÃncia de dados dificulta a anÃlise do desempenho de modelos hidrolÃgicos; ii) A quantificaÃÃo do assoreamento em reservatÃrios à essencial para a validaÃÃo de rotinas sedimentolÃgicas do modelo para longos perÃodos de avaliaÃÃo; iii) Os parÃmetros do solo sÃo determinantes na qualidade dos resultados e o detalhamento da parametrizaÃÃo melhora sensivelmente o desempenho do modelo WASA; iv) O predomÃnio do cenÃrio de estiagem para os prÃximos anos compromete o abastecimento devido ao baixo volume acumulado atualmente no reservatÃrio; v) A disponibilidade hÃdrica do reservatÃrio estratÃgico da bacia (Marengo) em anos extremos de baixa pluviometria, para uma vazÃo com 90% de garantia, à 96% inferior à disponibilidade para os anos mÃdios.
15
Franke, Ulrik. "Analysis of enterprise IT service availability : Enterprise architecture modeling for assessment, prediction, and decision-making." Doctoral thesis, KTH, Industriella informations- och styrsystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-101946.
Анотація:
Information technology has become increasingly important to individuals and organizations alike. Not only does IT allow us to do what we always did faster and more effectively, but it also allows us to do new things, organize ourselves differently, and work in ways previously unimaginable. However, these advantages come at a cost: as we become increasingly dependent upon IT services, we also demand that they are continuously and uninterruptedly available for use. Despite advances in reliability engineering, the complexity of today's increasingly integrated systems offers a non-trivial challenge in this respect. How can high availability of enterprise IT services be maintained in the face of constant additions and upgrades, decade-long life-cycles, dependencies upon third-parties and the ever-present business-imposed requirement of flexible and agile IT services? The contribution of this thesis includes (i) an enterprise architecture framework that offers a unique and action-guiding way to analyze service availability, (ii) identification of causal factors that affect the availability of enterprise IT services, (iii) a study of the use of fault trees for enterprise architecture availability analysis, and (iv) principles for how to think about availability management. This thesis is a composite thesis of five papers. Paper 1 offers a framework for thinking about enterprise IT service availability management, highlighting the importance of variance of outage costs. Paper 2 shows how enterprise architecture (EA) frameworks for dependency analysis can be extended with Fault Tree Analysis (FTA) and Bayesian networks (BN) techniques. FTA and BN are proven formal methods for reliability and availability modeling. Paper 3 describes a Bayesian prediction model for systems availability, based on expert elicitation from 50 experts. Paper 4 combines FTA and constructs from the ArchiMate EA language into a method for availability analysis on the enterprise level. The method is validated by five case studies, where annual downtime estimates were always within eight hours from the actual values. Paper 5 extends the Bayesian prediction model from paper 3 and the modeling method from paper 4 into a full-blown enterprise architecture framework, expressed in a probabilistic version of the Object Constraint Language. The resulting modeling framework is tested in nine case studies of enterprise information systems.Informationsteknik blir allt viktigare för både enskilda individer och för organisationer. IT låter oss inte bara arbeta snabbare och effektivare med det vi redan gör, utan låter oss också göra helt nya saker, organisera oss annorlunda och arbeta på nya sätt. Tyvärr har dessa fördelar ett pris: i takt med att vi blir alltmer beroende av IT-tjänster ökar också våra krav på att de är ständigt tillgängliga för oss, utan avbrott. Trots att tillförlitlighetstekniken går framåt utgör dagens alltmer sammankopplade system en svår utmaning i detta avseende. Hur kan man säkerställa hög tillgänglighet hos IT-tjänster som ständigt byggs ut och uppgraderas, som har livscykler på tiotals år, som är beroende av tredjepartsleverantörer och som dessutom måste leva upp till verksamhetskrav på att vara flexibla och agila? Den här avhandlingen innehåller (i) ett arkitekturramverk som på ett unikt sätt kan analysera IT-tjänsters tillgänglighet och ta fram rekommenderade åtgärder, (ii) ett antal identifierade kausalfaktorer som påverkar IT-tjänsters tillgänglighet, (iii) en studie av hur felträd kan användas för arkitekturanalys av tillgänglighet samt (iv) en uppsättning principer för beslutsfattande kring tillgänglighet. Avhandlingen är en sammanläggningsavhandling med fem artiklar. Artikel 1 innehåller ett konceptuellt ramverk för beslutsfattande kring IT-tjänsters tillgänglighet som understryker vikten av variansen hos nertidskostnaderna. Artikel 2 visar hur ramverk för organisationsövergripande arkitektur (s.k. enterprise architecture -- EA) kan utvidgas med felträdsanalys (FTA) och bayesianska nätverk (BN) för analys av beroenden mellan komponenter. FTA och BN är bägge etablerade metoder för tillförlitlighets- och tillgänglighetsmodellering. Artikel 3 beskriver en bayesiansk prediktionsmodell för systemtillgänglighet, baserad på utlåtanden från 50 experter. Artikel 4 kombinerar FTA med modelleringselement från EA-ramverket ArchiMate till en metod för tillgänglighetsanalys på verksamhetsnivå. Metoden har validerats i fem fallstudier, där de estimerade årliga nertiderna alltid låg inom åtta timmar från de faktiska värdena. Artikel 5 utvidgar den bayesianska prediktionsmodellen från artikel 3 och modelleringsmetoden från artikel 4 till ett fullständigt EA-ramverk som uttrycks i en probabilistisk version av Object Constraint Language (OCL). Det resulterande modelleringsramverket har testats i nio fallstudier på verksamhetsstödjande IT-system.
QC 20120912
16
Per, Närman. "Enterprise Architecture for Information System Analysis : Modeling and assessing data accuracy, availability, performance and application usage." Doctoral thesis, KTH, Industriella informations- och styrsystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-101494.
Анотація:
Decisions concerning IT systems are often made without adequate decision-support. This has led to unnecessary IT costs and failures to realize business benefits. The present thesis presents a framework for analysis of four information systems properties relevant to IT decision-making. The work is founded on enterprise architecture, a model-based IT and business management discipline. Based on the existing ArchiMate framework, a new enterprise architecture framework has been developed and implemented in a software tool. The framework supports modeling and analysis of data accuracy, service performance, service availability and application usage. To analyze data accuracy, data flows are modeled, the service availability analysis uses fault tree analysis, the performance analysis employs queuing networks and the application usage analysis combines the Technology Acceptance Model and Task-Technology Fit model. The accuracy of the framework's estimates was empirically tested. Data accuracy and service performance were evaluated in studies at the same power utility. Service availability was tested in multiple studies at banks and power utilities. Data was collected through interviews with system development or maintenance staff. The application usage model was tested in the maintenance management domain. Here, data was collected by means of a survey answered by 55 respondents from three power utilities, one manufacturing company and one nuclear power plant. The service availability studies provided estimates that were accurate within a few hours of logged yearly downtime. The data accuracy estimate was correct within a percentage point when compared to a sample of data objects. Deviations for four out of five service performance estimates were within 15 % from measured values. The application usage analysis explained a high degree of variation in application usage when applied to the maintenance management domain. During the studies of data accuracy, service performance and service availability, records were kept concerning the required modeling and analysis effort. The estimates were obtained with a total effort of about 20 man-hours per estimate. In summary the framework should be useful for IT decision-makers requiring fairly accurate, but not too expensive, estimates of the four properties.QC 20120912
17
Carrier, Emmanuel 1973. "Modeling the choice of an airline itinerary and fare product using booking and seat availability data." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/46552.
Анотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.Includes bibliographical references (p. 191-196).
Over the last ten years, the rapid growth of low-cost airlines and the development of web-based distribution of airline tickets have transformed the competitive environment in the airline industry worldwide. The relaxation of fares rules by low-cost airlines has disrupted the pricing and revenue management models of large network airlines. A better understanding of passenger choice behavior is now required to support the development of new strategies to compete more effectively in the current marketplace. In order to avoid the risk of bias associated with stated preference data, we focus in this research on how to develop a model of airline passenger choice based on booking data. Previous studies based on booking data have been limited to the sole choice of an airline itinerary and did not account for heterogeneity of behavior, a major characteristic of airline markets. This is due to the properties of booking data. For instance, only the chosen alternative is recorded in airline bookings and no information is available on other travel alternatives available at the time of the booking. Similarly, booking records contain no information on trip purpose that is traditionally used to segment airline markets. In this dissertation, we develop a modeling framework to overcome these limitations and extend booking-based passenger choice models to the joint choice of an airline itinerary and fare product. Booking data was combined with fare rules and seat availability data to incorporate the impact of pricing and revenue management and reconstruct the choice set of each booking. Characteristics of the traveler and the trip were retrieved from the booking records and used to replace trip purpose.
(cont.) They were included as explanatory variables of a latent class choice model in which several factors can be used simultaneously to segment the demand without necessarily dividing the bookings into many small sub-segments. In addition, a new formulation of a continuous function of time was proposed to model the time-of day preferences of airline travelers in short-haul markets. Instead of being set to a full 24 hours, the duration of the daily cycle was estimated to account for the low attractiveness of some periods of the day such as nighttime. Estimation results over a sample of 2000 bookings from three European short haul markets show that the latent class structure of the model and a continuous function of time led to a significant improvement in the fit of the model compared to previous specifications based on a deterministic segmentation of the demand or time-period dummies. In addition, the latent class model provides a more intuitive segmentation of the market between a core of time-sensitive business travelers and a mixed class of price-conscious business and leisure travelers. This research extends the scope of potential applications of passenger choice models to additional airline planning decisions such as pricing and revenue management. In particular, parameter estimates of the model were applied to forecast the sell-up behavior of airline passengers, a major input required by the newly proposed revenue management models designed to maximize revenues under less restricted fare structures.
by Emmanuel Carrier.
Ph.D.
18
Ren, Zongling. "Assessing speciation and availability of heavy metals in soils and soil solutions : an experimental and modeling study." Paris 7, 2014. http://www.theses.fr/2014PA077129.
Анотація:
Dans cette étude, la cellule de Donnan est couplée avec une colonne de sol (SC-DMT) et le dispositif DGT (Gradients de Diffusion dans les films minces de gels) ont été utilisés pour mesurer la concentration et la spéciation du Cd, Cu, Ni, Pb et du Zn dans dix-huit solutions de sol, couvrant un large éventail de sources (naturelle vs anthropique) et de concentration en métaux. Les sources de Cd, Cu, Pb, et Zn, disponibles dans des sols contaminés ont été évalués en combinant des extractions chimiques, la méthode de dilution isotopique multi-élémentaire (ID). Les quantités de métaux extraient chimiquement, échangées isotopiquement constituant un « pool » de métal disponible défini opérationnellement, ont ensuite été comparés pour mettre en évidence les relations entre la disponibilité chimique de métaux et leurs phases porteuses définis opérationnellement. Les modèles de complexation multi-surfaces ont été utilisés pour évaluer le rôle des principaux constituants du sol (matière organique, de l'argile, des hydroxydes de fer et hydroxydes de manganèse) dans le contrôle de la disponibilité chimique. La combinaison des approches analytiques et d'un modèle de spéciation peut fournir une validation mutuelle et un aperçu plus complet sur la disponibilité des métaux. Dans notre étude, la modélisation a généralement fournie une prévision adéquate de la spéciation des métaux dans la solution du sol et de la phase solide, et elle peut être un outil prometteur pour déchiffrer les mécanismes sous-jacents des différences de disponibilités des métaux dans les solsThe elevated heavy metal contamination in soils has given rise to the accurate assessment of the availability and mobility of heavy metals and the development of remediation strategies. In this study, soi! column-Donnan membrane technique (SC-DMT) and diffusive gradients in thin¬films gels (DGT) were used to measure the concentration and speciation of Cd, Cu, Ni, Pb, and Zn in eighteen soil solutions, covering a wide range of metal sources (natural and anthropogenic) and concentrations. The availability of Cd, Cu, Pb, and Zn in nine contaminated soils was evaluated by combining chemical extractions with multi-elementary stable isotopic dilution (ID) method. The isotopically exchangeable pool and the operationally defined pool determined by chemical extractions were then compared to probe the relationships between metal availabilities and their bearing phases. The mufti-surface model was used to assess the rote of the major soil components (organic matter, clay, iron hydroxides, and manganese hydroxides) in controlling metal availability. The combination of analytical approaches and speciation modeling can provide mutual validation and a more comprehensive picture of the availability of metals. In our work, model calculation generally provided an adequate prediction of metal speciation in soi! solution and solid phase, and it can be a promising tool to decipher the underlying mechanisms of the differences in metal availabilities in soils
19
Meng, Huixing. "Modeling Patterns for Performance Analysis of Production and Safety Systems in Process Industry." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX074/document.
Анотація:
Les systèmes de production et de sûreté de fonctionnement sont d'une importance majeure dans l'industrie des procédés. Leurs performances impactent directement les intérêts de l'industrie. Ces systèmes ont des comportements similaires. Ces comportements peuvent être conceptualisés dans des modèles via des patterns de modélisation. La réutilisation de ces patterns permet de rendre le processus de modélisation à la fois simplifiée et plus efficace.Dans cette thèse, nous proposons un ensemble varié de patterns de modélisation. Ils sont classés en fonction de leur usage, ce qui reflète le fonctionnement d'un pattern de modélisation. Les patterns sont présentés sous forme d’un catalogue. Sur la base de l'étude de nombreux systèmes de production et de sécurité, vingt-quatre (24) patterns de modélisation sont introduits. Chaque pattern est représenté par un ensemble d'éléments structurés. Nous proposons une méthodologie basée sur les patterns pour l'analyse des performances des systèmes de production et de sûreté de fonctionnement.Pour tester la pertinence des patterns de modélisation suggérés, nous avons mené des études expérimentales sur un ensemble de systèmes de production et de sûreté. Tous les systèmes de validation sont extraits de la littérature. Ces systèmes traitent la majorité des difficultés de modélisation détectées auparavant. Une comparaison est effectuée entre les résultats obtenus en utilisant la modélisation basée sur les patterns et ceux rapportés dans la littératureProduction and safety systems are crucial in the process industry. Their performances affect significantly the industry interests. These systems have common behaviors. Such behaviors can be captured in models via modeling patterns. By reusing modeling patterns, the modeling process can be simplified and made more efficient.In this thesis, we propose a versatile set of modeling patterns. They are classified according to their purpose, which reflects what a modeling pattern works for. Modeling patterns are exhibited as a catalog. Based on reviewing numerous production and safety systems, twenty-four (24) modeling patterns are introduced. Each pattern is illustrated with a set of structured items. We propose a pattern-based methodology for performance analysis of production and safety systems.To test the applicability of proposed modeling patterns, we conducted experimental studies on a set of production and safety systems. All systems are extracted from the literature. These systems are declared to cover most of modeling difficulties. Comparisons are performed between the results obtained using modeling patterns and those reported in the literature
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Rodrigues, Marcelo B. Karpowicz Mario. "An analysis of operational availability of Brazilian Navy and Argentine Air Force A-4 fleets using simulation modeling /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA376396.
Анотація:
Thesis (M.S. in Management) Naval Postgraduate School, December 1999."December 1999". Thesis advisor(s): Keebom Kang, Donald R. Eaton. Includes bibliographical references (p. 79-80). Also available online.
21
Rodrigues, Marcelo B., and Mario Karpowicz. "An analysis of operational availability of Brazilian Navy and Argentine Air Force A-4 fleets using simulation modeling." Thesis, Monterey California. Naval Postgraduate School, 1999. http://hdl.handle.net/10945/13466.
Анотація:
This thesis analyzes the impact of reducing transportation cycle time and consolidating aviation electronic component inventory management on the operational availability of the Brazilian Navy and Argentine Air Force AA fleets. The research is based on a scenario where the Brazilian Navy operates twenty A-4 aircraft, while the Argentine Air Force operates thirty AAs, and both countries rely on manufacturers in the United States for depot-level maintenance. The transportation turn-around-time is extremely long and the cost of some inventory items is very high. A simulation model was developed representing the repair process of a selected group of A4 critical electronic components. This particular model provides an effective managerial resource for long-term decision making to improve the readiness of aircraft fleet for both countries. We also developed a multiple regression analysis model (metamodel) to find the relationship between spare inventory levels and the operational availability. These results were applied to a linear programming model to find optimal spare levels for these critical components by minimizing the total cost while maintaining the desirable military readiness. Through a cost-effectiveness analysis, we compared the two situations, optimal spare levels with reduced transportation time and actual spare level with current transportation time. Our research concludes that both Armed Forces will improve readiness, while achieving significant savings, if they reduce the transportation time for the aviation electronic components sent to the United States for depot-level maintenance, and collaborate on the inventory management of their A-4 fleets.
22
Горбачев, В. А. "Malicious Hardware: characteristics, classification and formal models." Thesis, IEEE, 2014. http://openarchive.nure.ua/handle/document/3435.
Анотація:
Electronic Systems (ES) that contain embedded malicious hardware represent a serious threat, especially for government, aeronautic, financial and energy system applications. MHs can be implemented as hardware modifications to application specific ICs (ASICs), microprocessors, digital signal processors, or as IP core modifications for field programmable gate arrays (FPGA) [1]. They are able to turn off the CPU, to send confidential information and bypass the software user authentication mechanisms. There are some important characteristics of this type of threat: standard testing methods, such as the common functional verification and Automatic Test Pattern Generation (ATPG) cannot always be used to solve the problem of detecting MH [2], [3]; identification of the threat sources without special tools is practically impossible; even in cases when an information security violation is detected, it is very difficult to prove that this action was performed by MH. These and other features make MHs very promising embedded devices for planning of electronic terrorism. Therefore, detecting and preventing approaches are in the attention centre of IT systems security investigation.
23
Allen, Eric B. "Dendrochronology in Northern Utah: Modeling Sensitivity and Reconstructing Logan River Flows." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1716.
Анотація:
Semi-arid valleys in northern Utah are home to the majority of the state population and are dependent upon winter snowpack in surrounding mountains for water for irrigation, hydropower and municipal use. Water is delivered to the urban areas in the spring as discharge in rivers draining the mountains. Understanding the natural variability and cycles of wet and dry periods enables water managers to make informed water allocations. However, the complex regional climate teleconnections are not well understood and the shortness of the instrumental period does not allow for a full understanding of natural variability. Paleo proxies can be used to extend the instrumental record and better capture natural variability. This study uses dendrochronology to reconstruct streamflows of the Logan River in northern Utah over the last several centuries to provide water managers with a better understanding of natural variability. This reconstruction involved sampling and creating three Douglas-fir, one limber pine and two Rocky Mountain juniper chronologies in northern Utah. Combined with existing chronologies, three flow reconstructions of the Logan River were created: one using only within basin chronologies, one using all considered chronologies and one long chronology. Employing regional chronologies resulted in the most robust models, similar to other findings. Results indicate that the last several centuries exhibited greater variability and slightly higher mean annual flows than in the instrumental record (1922-2011). These reconstructions were created using species well established within the dendroclimatology literature such as of Douglas-fir and limber pine and the lesser used Rocky Mountain juniper. The success of Rocky Mountain juniper suggests that it can be a useful species for dendroclimatology in other areas lacking more widely recognized species in semi-arid climates (e.g., pinyon pine).
24
Hou, Wei. "Integrated Reliability and Availability Aanalysis of Networks With Software Failures and Hardware Failures." Scholar Commons, 2003. https://scholarcommons.usf.edu/etd/1393.
Анотація:
This dissertation research attempts to explore efficient algorithms and engineering methodologies of analyzing the overall reliability and availability of networks integrated with software failures and hardware failures. Node failures, link failures, and software failures are concurrently and dynamically considered in networks with complex topologies. MORIN (MOdeling Reliability for Integrated Networks) method is proposed and discussed as an approach for analyzing reliability of integrated networks. A Simplified Availability Modeling Tool (SAMOT) is developed and introduced to evaluate and analyze the availability of networks consisting of software and hardware component systems with architectural redundancy. In this dissertation, relevant research efforts in analyzing network reliability and availability are reviewed and discussed, experimental data results of proposed MORIN methodology and SAMOT application are provided, and recommendations for future researches in the network reliability study are summarized as well.
25
Hou, Wei. "Integrated reliability and availability analysis of networks with software failures and hardware failures." [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000173.
26
Garg, Gaurav. "Quantifying long term changes in streamflow characteristics in Texas." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1456.
Анотація:
Streamflow characteristics change over time as a result of water resources
development and management projects, water use, watershed land use changes, and
climate changes. The main objective of this thesis is to assess the significance of the
impacts of human activities such as construction of reservoirs, water supply diversions,
increased water use and return flows on streamflows by the recently completed Texas
WAM (Water Availability Modeling) system. The major river basins in the state of
Texas were selected as suitable study basins. The particular objective is accomplished by
the assessment of WAM monthly and annual naturalized and regulated flows, based on
using the WRAP (Water Rights Analysis Package) model, which represents the
river/reservoir management model. WAM flow frequency analysis was performed for
the simulated flows. The flow ratio indices developed showed the divergence of the
actual flows from their natural behavior for the entire monthly flow frequency flow
spectrum ranging from minimum flows to high flows. This study describes the combined
effects of reservoir construction, increased water use, water resources development
projects and land use changes on the river flow regime.
27
Bhat, Aniket Anant. "Stochastic Petri Net Models of Service Availability in a PBNM System for Mobile Ad Hoc Networks." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/10000.
Анотація:
Policy based network management is a promising approach for provisioning and management of quality of service in mobile ad hoc networks. In this thesis, we focus on performance evaluation of this approach in context of the amount of service received by certain nodes called policy execution points (PEPs) or policy clients from certain specialized nodes called the policy decision points (PDPs) or policy servers. We develop analytical models for the study of the system behavior under two scenarios; a simple Markovian scenario where we assume that the random variables associated with system processes follow an exponential distribution and a more complex non-Markovian scenario where we model the system processes according to general distribution functions as observed through simulation. We illustrate that the simplified Markovian model provides a reasonable indication of the trend of the service availability seen by policy clients and highlight the need for an exact analysis of the system without relying on Poisson assumptions for system processes. In the case of the more exact non-Markovian analysis, we show that our model gives a close approximation to the values obtained via empirical methods. Stochastic Petri Nets are used as performance evaluation tools in development and analysis of these system models.Master of Science
28
Malrait, Luc. "Modeling and control of server systems : application to performance and dependability." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENT100/document.
Анотація:
Les serveurs informatiques permettent de mettre en œuvre un large éventail de services en ligne et d'applications telles que les services Web, les services de messagerie ou les services de base de données. Cependant, leur configuration ad hoc soulève des problématiques cruciales liées à la performance, la disponibilité et le coût économique des applications. Dans cette thèse, nous étudions l'impact de la configuration des serveurs sur le compromis central entre performance et disponibilité du service. Dans une première partie, nous modélisons le comportement de serveurs uniques à l'aide d'approximations fluides et développons des lois de commandes novatrices pour le contrôle d'admission sur les systèmes de serveurs centralisés. Nous proposons plusieurs lois de commande pour différentes combinaisons d'objectifs de qualité de service et de niveau de service. Parmi elles, AM-C garantit un objectif de performance du service en maximisant sa disponibilité; PM-C garantit un objectif de disponibilité du service en maximisant sa performance. Nous évaluons expérimentalement le modèle ainsi que les stratégies de contrôle sur TPC-C, un benchmark industriel reconnu qui reproduit un service d'e-commerce, implémenté sur le serveur de base de données PostgreSQL. Nos expériences montrent que les techniques proposées améliorent jusqu'à 30% les performances du service tout en garantissant les contraintes de disponibilité. Dans une deuxième partie, nous étendons ce travail aux systèmes de serveurs distribués, qui sont largement utilisés par les applications Internet évoluant sur des systèmes multi-niveaux hébergés par des clusters de serveurs. Nous présentons un modèle de serveur distribué comme un modèle continu non linéaire en faisant une analogie avec les systèmes transferts de fluide. Nous formalisons alors un problème d'optimisation pour le contrôle de ces systèmes. Nous fournissons un contrôle d'admission qui permet d'obtenir la disponibilité de service la plus élevée tout en garantissant un objectif de performance. Une évaluation numérique du modèle proposé et du contrôle distribué associé est présentée et montre que la configuration optimale de ces systèmes n'est pas intuitiveServer technology provides a means to support a wide range of on-line services and applications, such as web services, e-mail services, database services. However, their ad hoc configuration poses significant challenges to the performance, availability and economical costs of applications. In this thesis, we examine the impact of server configuration on the central trade-off between service performance and service availability. First, we model the behavior of single servers using fluid approximations. Second, we develop novel ad- mission control laws of central server systems. We provide several control laws for different combinations of quality-of-service and service level objectives. Among them, AM-C , the availability-maximizing admission control law, achieves the highest service availability while meeting given performance objective; PM-C is a performance-maximizing ad- mission control law that meets a desired availability target with the highest performance. We evaluate our fluid model and control techniques on the TPC-C industry-standard benchmark that implements a warehouse running on the PostgreSQL database server. Our experiments show that the proposed techniques successfully improve performance by up to 30 % while guaranteeing availability constraints. Furthermore, we extend this work to distributed server systems, that are widely used by Internet applications in the farm of server clusters and multi-tier systems. We present a distributed server model as a non-linear continuous-time model using analogies with fluid transfer. We then state an optimization problem for the control of distributed server systems. We provide an admission control that allows to get the highest service availability while a target performance level is guaranteed. Numerical evaluations of the proposed distributed model and control are presented, and show that the optimal configuration of such systems is not intuitive
29
Wernecke, Gerhard Danre. "Reduce maintenance resources and increase plant availability by utilising web-based condition monitoring systems and Markovian modeling techniques / G.D. Wernecke." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1488.
30
Sayad, Khaled. "Cross-domain Resilience in Cloud-native, Critical Cyber-Physical Systems Networks : Availability Modeling, Analysis, and Optimization of Critical Services Provisioning." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST028.
Анотація:
La résilience des Infrastructures Critiques (ICs) est cruciale pour assurer la sécurité et la stabilité socio-économique dans la société moderne. Ces ICs s'appuient sur un réseau complexe de systèmes cyber-physiques (SCPs) couvrant plusieurs domaines tels que les télécommunications et l'énergie, an de garantir un flux continu de services critiques.L'évolution du mode opérationnel des ICs modernes, illustré par l'intégration accrue des technologies cloud-natif dans les réseaux SCPs sous-jacents, introduit de nouveaux dés en termes de résilience face aux cyber-risques, qui s'ajoute au problème du dimensionnement optimal du réseau des SCPs avec la contrainte des coûts de déploiement qui résultent des schémas de protection géo-redondant. Dans cette thèse, nous attaquons ces dés en premier lieu par le développement d'un modèle d'évaluation de disponibilité avec comme objectif, la quantication de l'efficacité d'adoption des schémas de protection croisée. Ensuite, on présente un modèle d'orchestration optimale des ressources cloud-natifs mutualisées avec l'objectif de minimiser les coûts des schémas de protection. Enfin, nous abordons la problématique de coordination inter-opérateurs d'ICs d'un point de vue "confiance" en proposant une plateforme de partage d'information et de ressource qui exploite la convergence des paradigmes cloud-natif des DataSpacesThe dependability of Critical Infrastructures (CIs) operations is crucial to ensuresecurity and socio-economic stability in modern society. These CIs rely on a complex network of Critical Cyber-Physical Systems (CCPSs), spanning multiple domains such as telecommunication and energy, to guarantee a continuous ow of critical services. The paradigm shift in modern CIs' operational mode, illustrated by the increased integration of cloud-native technologies in the underlying CCPSs networks, brings more challenges in terms of resilience against cyber-risks, and increased deployment costs due to redundancy-based protection schemes. In this dissertation, we tackle these challenges by, first, proposing a model-based, cross-domain dependability evaluation to assess the availability of cloud-native, interdependent critical services and quantify the impact of adopting cross-domain protection mechanisms on critical services' dependability. Secondly, we study the problem of optimal service provisioning based on resource sharing in cloud-native, CCPSs networks with deployment cost and performance constraints. Finally, we tackle the problem of cross-domain coordination from a Trust perspective by proposing an architecture for secure and trustful information and resource sharing that exploits the convergence of cloud-native management and DataSpaces paradigm to ensure secure, trustful, and sovereign coordination
31
Dong, Chunyu [Verfasser], and Lucas [Akademischer Betreuer] Menzel. "Assessing the availability of remote sensing, hydrological modeling and in situ observations in snow cover research / Chunyu Dong ; Betreuer: Lucas Menzel." Heidelberg : Universitätsbibliothek Heidelberg, 2016. http://d-nb.info/1180616294/34.
32
Godre, Alexandra M. "Effects of Climate Change on Water Depth and an Ecosystem Indicator Species – Future Muskrat Lodge Habitat Availability in a Lake Erie Estuary." University of Toledo / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1579266625628504.
33
Wagena, Moges Berbero. "Quantifying the Impact of Climate Change on Water Availability and Water Quality in the Chesapeake Bay Watershed." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82420.
Анотація:
Climate change impacts hydrology, nutrient cycling, agricultural conservation practices, and greenhouse gas (GHG) emissions. The Chesapeake Bay and its watershed are subject to the largest and most expensive Total Maximum Daily Load (TMDL) ever developed. It is unclear if the TMDL can be met given climate change and variability (e.g., extreme weather events). The objective of this dissertation is to quantify the impact of climate change and climate on water resources, nutrient cycling and export in agroecosystems, and agricultural conservation practices in the Chesapeake Bay watershed. This is accomplished by developing and employing a suite of modelling tools.
GHG emissions from agroecosystems, particularly nitrous oxide (N2O), are an increasing concern. To quantify N2O emissions a routine was developed for the Soil and Water Assessment Tool (SWAT) model. The new routine predicts N2O and di-nitrogen (N2) emissions by coupling the C and N cycles with soil moisture, temperature, and pH in SWAT. The model uses reduction functions to predict total denitrification (N2 + N2O production) and partitions N2 from N2O using a ratio method. The SWAT nitrification routine was modified to predict N2O emissions using reduction functions. The new model was tested using GRACEnet data at University Park, Pennsylvania, and West Lafayette, Indiana. Results showed strong correlations between plot measurements of N2O flux and the model predictions for both test sites and suggest that N2O emissions are particularly sensitive to soil pH and soil N, and moderately sensitive to soil temperature/moisture and total soil C levels.
The new GHG model was then used to analyze the impact of climate change and extreme weather conditions on the denitrification rate, N2O emissions, and nutrient cycling/export in the 7.4 km2 WE38 watershed in Pennsylvania. Climate change impacts hydrology and nutrient cycling by changing soil moisture, stoichiometric nutrient ratios, and soil temperature, potentially complicating mitigation measures. To quantify the impact of climate change we forced the new GHG model with downscaled and bias-corrected regional climate model output and derived climate anomalies to assess their impact on hydrology, nitrate (NO3-), phosphorus (P), and sediment export, and on emissions of N2O and N2. Model-average (± standard deviation) results indicate that climate change, through an increase in precipitation, will result in moderate increases in winter/spring flow (2.7±10.6 %) and NO3- export (3.0±7.3 %), substantial increases in dissolved P (DP, 8.8±19.8 %), total P (TP, 4.5±11.7 %), and sediment (17.9±14.2 %) export, and greater N2O (63.3±50.8 %) and N2 (17.6±20.7 %) emissions. Conversely, decreases in summer flow (-12.4±26.7 %) and the export of P (-11.4±27.4 %), TP (-7.9±24.5 %), sediment (-4.1±21.4 %), and NO3- (-12.2±31.4 %) are driven by greater evapotranspiration from increasing summer temperatures. Increases in N2O (20.1±29.3 %) and decreases in N2 (-13.0±14.6 %) are also predicted in the summer and driven by increases in soil moisture and temperature.
In an effort to assess the impact of climate change at a regional level, the model was then scaled-up to the entire Susquehanna River basin and was used to evaluate if agricultural best management practices (BMPs) can offset the impact of climate change. Agricultural BMPs are increasingly and widely employed to reduce diffuse nutrient pollution. Climate change can complicate the development, implementation, and efficiency of BMPs by altering hydrology, nutrient cycling, and erosion. We select and evaluate four common BMPs (buffer strips, strip crop, no-till, and tile drainage) to test their response to climate change. We force the calibrated model with six downscaled global climate models (GCMs) for a historic period (1990-2014) and two future scenario periods (2041-2065) and (2075-2099) and quantify the impact of climate change on hydrology, NO3-, total N (TN), DP, TP, and sediment export with and without BMPs. We also tested prioritizing BMP installation on the 30% of agricultural lands that generate the most runoff (e.g., critical source areas-CSAs). Compared against the historical baseline and excluding the impact of BMPs, the ensemble model mean (± standard deviation?) predictions indicate that climate change results in annual increases in flow (4.5±7.3%), surface runoff (3.5±6.1%), sediment export (28.5±18.2%) and TN (9.5±5.1%), but decreases in NO3- (12±12.8%), DP (14±11.5%), and TP (2.5±7.4%) export. When agricultural BMPs are simulated most do not appreciably change the overall water balance; however, tile drainage and strip crop decrease surface runoff generation and the export of sediment, DP, and TP, while buffer strips reduced N export substantially. Installing BMPs on critical source areas (CSAs) results in nearly the same level of performance for most practices and most pollutants. These results suggest that climate change will influence the performance of BMPs and that targeting BMPs to CSAs can provide nearly the same level of water quality impact as more widespread adoption.
Finally, recognizing that all of these model applications have considerable uncertainty associated with their predictions, we develop and employ a Bayesian multi-model ensemble to evaluate structural model prediction uncertainty. The reliability of watershed models in a management context depends largely on associated uncertainties. Our Objective is to quantify structural uncertainty for predictions of flow, sediment, TN, and TP predictions using three models: the SWAT-Variable Source Area model (SWAT-VSA), the standard SWAT model (SWAT-ST), and the Chesapeake Bay watershed model (CBP-model). We initialize each of the models using weather, soil, and land use data and analyze outputs of flow, sediment, TN, and TP for the Susquehanna River basin at the Conowingo Dam in Conowingo, Maryland. Using these three models we fit Bayesian Generalized Non - Linear Multilevel Models (BGMM) for flow, sediment, TN, and TP and obtain estimated outputs with 95% confidence intervals. We compare the BGMM results against the individual model results and straight model averaging (SMA) results using a split time period analysis (training period and testing period) to assess the BGMM in a predictive fashion. The BGMM provided better predictions of flow, sediment, TN, and TP compared to individual models and the SMA during the training period. However, during the testing period the BGMM was not always the best predictor; in fact, there was no clear best model during the testing period. Perhaps more importantly, the BGMM provides estimates of prediction uncertainty, which can enhance decision making and improve watershed management by providing a risk-based assessment of outcomes.Ph. D.
34
Costa, Carlos Alexandre Gomes. "Soil moisture and water availability in the root zone under natural conditions of preserved Caatinga." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8261.
Анотація:
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoA Ãgua na bacia hidrogrÃfica està distribuÃda em diversos compartimentos importantes no que se refere à ecohidrologia. Muitos estudos em regiÃes semiÃridas apontam os reservatÃrios superficiais como principais compartimentos de Ãgua. Entretanto, a bacia hidrogrÃfica tem maior abrangÃncia que as bacias hidrÃulicas nela contida, e os recursos hÃdricos nos compartimentos distribuÃdos na bacia hidrogrÃfica (como no solo) devem ser analisados nÃo somente no que se refere aos usos ecolÃgicos, mas tambÃm como espaÃo de disponibilidade hÃdrica. Portanto, o objetivo do trabalho foi analisar, com base em medidas e modelagem, a dinÃmica da Ãgua nos solos de uma bacia semiÃrida de Caatinga preservada e seu impacto sobre a disponibilidade hÃdrica. Para isso foi medida, entre outros, a umidade do solo a cada hora, de 2003 a 2010 (2923 dias) na Bacia Experimental de Aiuaba (BEA, 12 kmÂ), totalmente preservada e com precipitaÃÃo mÃdia anual de 560 mm. O monitoramento foi realizado atravÃs de trÃs sensores TDR, um instalado em cada uma das trÃs associaÃÃes entre solo e vegetaÃÃo (SVA) identificadas na bacia. O mÃtodo de investigaÃÃo considerou seis etapas principais: i) determinaÃÃo da profundidade efetiva das raÃzes da Caatinga preservada; ii) calibraÃÃo dos sensores de umidade tipo TDR; iii) representaÃÃo espaÃo-temporal da umidade do solo em cada unidade de SVA; iv) anÃlise da disponibilidade hÃdrica do solo na zona das raÃzes; v) parametrizaÃÃo do modelo hidrolÃgico WASA-SED; e vi) parametrizaÃÃo do modelo hidrolÃgico DiCaSM. Os resultados obtidos nesta pesquisa indicam a importÃncia da abordagem da anÃlise temporal da umidade do solo e da disponibilidade hÃdrica do solo na zona das raÃzes para a manutenÃÃo do bioma Caatinga. Mais especificamente, foi observado que a profundidade efetiva do sistema radicular na BEA oscilou entre 70 e 80 cm nas regiÃes com solos profundos, porÃm, em regiÃes com solos rasos, observou-se que a profundidade efetiva das raÃzes adaptou-se Ãs restriÃÃes, ficando reduzida a menos de 40 cm. AlÃm disso, a anÃlise sazonal demonstrou que, na estaÃÃo de estio, as raÃzes tÃm comprimentos atà 11 cm menores, abrindo, portanto, poros secundÃrios que facilitarÃo a penetraÃÃo da Ãgua nas eventuais chuvas dos meses secos (junho a dezembro), assim como nas primeiras chuvas da estaÃÃo Ãmida. Nas duas SVAs cujos solos sÃo profundos e cuja vegetaÃÃo à densa, a Ãgua no solo encontra-se ânÃo-disponÃvelâ (isto Ã, abaixo do ponto de murcha permanente â WP) em quase nove meses ao ano (72% do tempo); e somente durante trÃs meses ao ano (25%) a Ãgua no solo encontra-se disponÃvel. Nos 3% restantes do ano (cerca de 10 dias) hà Ãgua gravitacional nessas SVAs. Na SVA cujo solo à raso e cuja vegetaÃÃo à esparsa, a dinÃmica da Ãgua no solo à diferente: o tempo em que hà Ãgua gravitacional, disponÃvel e nÃo disponÃvel à praticamente o mesmo (quatro meses ao ano). Isso se deve, entre outros, à baixa umidade do solo no ponto de murcha permanente do neossolo litÃlico; e à sua restrita espessura, gerando saturaÃÃo muito mais frequentemente que nos demais solos que â ao contrÃrio deste â dispÃem de drenagem profunda. A depleÃÃo da Ãgua no solo sob condiÃÃes de umidade abaixo do ponto de murcha foi outro resultado importante desta pesquisa. Nas duas associaÃÃes com solos profundos e vegetaÃÃo densa, observou-se â ao longo de todo o perÃodo investigado â decaimento contÃnuo da umidade atà que a mesma se aproximasse assintoticamente da umidade residual. AnÃlise mais detalhada demonstrou que a reduÃÃo da umidade do solo entre o WP e a umidade residual sempre obedecia ao decaimento exponencial. Na associaÃÃo com solo raso e vegetaÃÃo esparsa observou-se que a umidade nÃo caÃa para valores inferiores ao WP, mesmo sujeita ao mesmo rigor climÃtico das demais associaÃÃes. Considerando-se: (i) que em solo tÃo seco, a drenagem à improvÃvel; e (ii) que os processos associados de percolaÃÃo e evaporaÃÃo tampouco devam ser os responsÃveis pela retirada de Ãgua do solo (posto que o fenÃmeno nÃo se observa na SVA cujo solo à raso e, portanto, mais quente); levanta-se a hipÃtese que o secamento do solo nessas condiÃÃes deva ser causado por extraÃÃo de Ãgua pela vegetaÃÃo. Isso reforÃaria a tese de que a Caatinga dispÃe de adaptaÃÃo para sobreviver mesmo em condiÃÃes de estresse hÃdrico. Os modelos hidrolÃgicos WASA-SED e DiCaSM nÃo conseguiram representar adequadamente a dinÃmica temporal da Ãgua nos solos da BEA. No entanto, os modelos reproduziram satisfatoriamente as curvas de permanÃncia da umidade dos solos, permitindo representar a disponibilidade hÃdrica na zona das raÃzes para fins de planejamento. Por fim, logrou-se avaliar â quantitativa, espacial e temporalmente â a disponibilidade hÃdrica do solo. Esta à da mesma ordem de grandeza da disponibilidade de um reservatÃrio superficial Ãtimo. Em termos quantitativos, a disponibilidade no solo chega a ser quase cinco vezes superior à do reservatÃrio superficial, entretanto, a garantia associada da Ãgua superficial (90%) à bem superior à permanÃncia da Ãgua disponÃvel na BEA: apenas 28% nas Ãreas com solos profundos e 65% nas Ãreas com solos rasos.
Regarding ecohydrology, the catchment water is distributed over several important compartments. Many studies in semiarid re gions indicate the surface reservoirs as the main water compartments. However, the watershed has greater scope than the water reservoirs contained therein, and water resources in compartments distributed in the watershed (like in soil) should be analyzed not only with regard to ecological uses, but also as spaces of water availability. Therefore, the object ive of this work was to analyze, based on measurements and modeling, the water dynamics in th e soils of a semi-arid basin in preserved Caatinga, and its impact on water availability. Wit h this in mind, it was measured, among others, the soil moisture, every hour, from 2003 to 2010 (2923 days) in the Aiuaba Experimental Basin (AEB, 12 km Â), fully preserved and with average annual rainfall of 560 mm. Monitoring was carried out through three TDR se nsors, one installed in each of the three soil and vegetation associations (SVA) identified in the basin. The research method considered six main steps: i) assessment of the eff ective root depth of preserved Caatinga ii) calibration of humidity TDR sensors iii) space-time representation of soil moisture in each SVA unit iv) analysis of soil water availability in the root zone, v) parameterization of the WASA-SED hydrological model, and vi) parameterizati on of the DiCaSM hydrological model. The results of this research indicate the importance of addressing the temporal analysis of soil moisture and soil water availability in the root zone to maintain the Caatinga biome. More specifically, it was observed that the effecti ve depth of the root system on AEB ranged between 70 and 80 cm in areas with deep soils, but in areas with shallow soils, it was observed that the effective depth of the roots had adapted to the constraints, having been reduced to less than 40 cm. Furthermore, the season al analysis showed that in the dry season, the roots have lengths up to 11 cm smaller, openin g, therefore, secondary pores that facilitate the penetration of what little rain water falls in the dry months (June-December), as well as in the first rains of the wet season. In the two SVAs whose soils are deep and the vegetation is dense, the soil water is 'not available' (ie below the permanent wilting point - WP) during nearly nine months a year (72% of the time), and on ly during three months of the year (25% of the time) the soil water is available. In the re maining 3% of the year (about 10 days) there is gravitational water in these SVAs. In the SVAs whose soil is shallow and whose vegetation is sparse, the dynamics of soil water are different : the time when there is gravitational water, available and unavailable, is practically the same (four months a year). This is due to, among other things, the low soil moisture at the permanen t wilting point of the Udorthent, and to its limited thickness, generating saturation much more frequently than in others that - unlike this one - have deep drainage. The depletion of soil wat er under conditions of moisture below the wilting point was another important result of this research. In the two associations with deep soils and thick vegetation, it was observed â throu ghout the observation period â continuous fall of moisture level until it approached asymptot ically the residual moisture. More detailed analysis showed that the reduction of soil moisture between the WP and the residual moisture level always followed the exponential decay. It was observed, in the association of shallow soil and sparse vegetation, that the moisture did not fall to below the WP, even subjected to the same rigorous climate of the other associations . Considering: (i) that in such a dry soil, the drainage is unlikely, and (ii) that the associated processes of percolation and evaporation should not be responsible for the removal of soil w ater either (since the phenomenon is not observed in SVAs whose soil is shallow and therefor e warmer) , it is raised the hypothesis that the soil drying under these conditions must be caused by water extraction by vegetation. This would strengthen the argument that the Caating a has adapted to survive under water stress. The hydrological models WASA-SED and DiCaSM failed to adequately represent the temporal dynamics of soil water in the AEB. However , the models did satisfactorily reproduce the retention curves of soil moisture, al lowing the representation of the water availability in the root zone for planning purposes . Finally, we managed to evaluate - quantitatively, spatially and temporally â the soil water availability. This availability is of the same order of magnitude of the availability of an o ptimal surface reservoir. The availability in the soil, in quantitative terms, can be almost five times higher than that of the surface reservoir. However, the security associated with su rface water (90%) is much higher than the water permanence available in the AEB: just 28% in areas with deep soils and 65% in areas with shallow soils.
35
Idrissou, Mouhamed [Verfasser]. "Modeling water availability for smallholder farming in inland valleys under climate and land use / land cover change in Dano, Burkina Faso / Mouhamed Idrissou." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1218301430/34.
36
Arjona, Martínez Jamie. "Designing smart ITS services through innovative data analysis modeling." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/671615.
Анотація:
Nowadays, one of the most important problems in urban areas concerns traffic congestion. This, in turn, has an impact on the economy, nature, human health, city architecture, and many other facets of life. Part of the vehicular traffic in cities is caused by parking space availability. The drivers of private vehicles usually want to leave their vehicles as close as possible to their destination. However, the parking slots are limited and may not be enough to sustain the demand, especially when the destination pertains to an attractive area. Thus, individuals looking for a place to park their vehicles contribute to increasing traffic flow density on roads where the parking demand cannot be satisfied.
An Internet of Things (IoT) approach allows us to know the state of the parking system (availability of the parking slots) in real time through wireless networks of sensor devices. An intelligent treatment of this data could generate forecasted information that may be useful in improving management of on-street parking, thus having a notable effect on urban traffic. Smart parking systems first appeared in 2015, with IoT platforms in Santander, San Francisco and Melbourne. That is the year when those cities began to provide on-street real-time parking data in order to offer new services to their citizens. One of the most interesting services that these kinds of platforms can offer is parking availability forecasting, for which the first works in this field studied the temporal and spatial correlations of parking occupancy to support short-term forecasts (no more than 30 minutes). Those short-term forecasts are not useful at all to the end user of this service; thus, the necessary prediction intervals should be at the order of magnitude of hours.
In this context, this thesis focuses on using parking and other sources of data to characterize and model different parking systems. The methodology used employs novel techniques for providing real-time forecasts of parking availability based on data from sensors with certain inaccuracies due to their mechanical nature. The models are developed from four different methodologies: ARIMA, multilayer perceptron (MLP), long-short term memory (LSTM) and gated recurrent unit (GRU). The first has been the standard approach to forecasting in the ITS literature, while the latter ones have proven to be the best neural network (NN) architectures for solving a wide set of sequential data problems, such as those presented in this work. As far as we know, LSTM and GRU methods (recurrent neural network approaches) have been used recently with good results in traffic forecasting, but not for parking. In addition, we propose using exogenous data such as weather conditions and calendar effects, thereby converting the problem from univariate to multivariate. It is shown here how NN methods naturally handle the increased complexity in the problem. The reason for using exogenous variables is that they can offer relevant information that cannot be inferred from the sensor measurements.
The proposed methods have been intensively compared by creating parking models for parking sectors in five cities around the world. The results have been analysed in order to identify and provide exhaustive guidelines and insights into the inner mechanisms of parking systems while also ascertaining how the idiosyncrasies of each method are reflected in the model forecasts.
When comparing the results according to their disciplines of origin (ARIMA from statistics and NN methods from machine learning), neither of the proposed methodologies is clearly better than the other, as both can provide forecasts with low error but by different means. ARIMA has shown lower error rates in small-sized sectors where the more recent status of the parking system is more relevant; while the NN methods are more capable of providing forecasts for large-sized sectors where patterns are dependent on long time horizons.En la actualidad uno de los mayores problemas de las zonas urbanas tiene origen en la congestión del tráfico con un alto impacto en la economía, el medio ambiente, la salud y otras facetas de la vida urbana. En muchas ocasiones parte de la congestión del trafico tiene origen en la disponibilidad de las plazas de aparcamiento debido a que los conductores de vehículos privados suelen querer aparcar sus vehículos lo más cerca posible de su destino pero las plazas de aparcamiento son limitadas y pueden no ser suficientes para mantener la demanda. Un enfoque basado en el Internet of Things (IoT) nos permite en tiempo real conocer la disponibilidad de plazas de estacionamiento a través de redes inalámbricas de sensores. Un tratamiento inteligente sobre estos datos puede generar información que ayude a predecir la futura demanda de estacionamiento en las zonas sensorizadas mejorando así la gestión del estacionamiento y teniendo un efecto en el tráfico urbano. Los primeros trabajos académicos en este área se centraron en estudiar las correlaciones temporales y espaciales de la ocupación del estacionamiento para proveer pronósticos a corto plazo (predicciones a tiempo máximo de 30 minutos) y que en muchas ocasiones no son de utilidad ya que para el usuario final es preferible tener estimaciones de la disponibilidad de estacionamiento en el order de magnitud de horas. En este contexto, esta tesis se centra en el uso de datos de aparcamientos y otras fuentes para caracterizar y modelizar diferentes sistemas de aparcamiento. La metodología utilizada emplea técnicas innovadoras para proporcionar predicciones en tiempo real sobre la disponibilidad de aparcamiento basadas en datos de sensores. Los modelos se desarrollan a partir de cuatro metodología: Autoregressive Integrated Moving Average (ARIMA), Multilayer Perceptron (MLP), Long-Short Term Memory (LSTM) y Gated Recurrent Unit (GRU). La primera ha sido el enfoque estándar de predicción en la literatura sobre Sistemas de Transporte Inteligentes, mientras que las otras tres han demostrado ser las mejores arquitecturas de redes neuronales para resolver un amplio conjunto de problemas de datos de naturaleza secuencial, como los que se tratan en este trabajo. Hasta donde sabemos, los métodos LSTM y GRU (enfoques de redes neuronales recurrentes) se han utilizado recientemente para la predicción de tráfico, obteniendo buenos resultados, pero no para aparcamiento. Además, proponemos utilizar datos exógenos como las condiciones meteorológicas y los efectos del calendario, transformando el problema de univariante a multivariante y demostramos como los métodos de redes neuronales gestionan de forma natural esta mayor complejidad del problema. El motivo para incluir variables exógenas es el de reducir la incertidumbre dada por las mediciones de los sensores ya que el uso de los sistemas de aparcamiento está condicionado por procesos no medibles por estos. Los métodos propuestos se han comparado mediante la creación de modelos para sectores de aparcamiento en cinco ciudades. Los resultados se han analizado con el fin de identificar y proporcionar pautas exhaustivas y conocimientos sobre los mecanismos internos de los sistemas de estacionamiento y, al mismo tiempo, determinar cómo se reflejan las idiosincrasias de cada método y de cada sector en los pronósticos del modelo. Al comparar los resultados según sus disciplinas de origen (ARIMA de estadística y redes neuronales de aprendizaje automático), ninguna de las metodologías propuestas es claramente mejor que las otras, ya que ambas pueden proporcionar predicciones con bajo error. ARIMA ha demostrado tener tasas de error más bajas en sectores de aparcamiento de menor dimensión donde el estado más reciente del sistema es más relevante; mientras que los métodos de redes neuronales has demostrado ser capaces de proporcionar mejores predicciones para sectores de gran tamaño donde los patrones tienen mayores dependencias temporales
Programa de doctorat: Estadística i investigació operativa
37
Pilla, Rachel Marie. "Lake Vertical Ecosystem Responses to Climate and Environmental Changes: Integrating Comparative Time Series, Modeling, and High-Frequency Approaches." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1620646716185966.
38
Macêdo, Rodrigo Freire de. "Proposta metodológica para a avaliação de cenários de disponibilidade e oferta hídrica." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-18042016-110411/.
Анотація:
Este trabalho de dissertação objetiva uma proposta metodológica para a análise da relação entre cenários futuros de disponibilidade hídrica superficial e demanda hídrica, levando-se em consideração a evolução dos fatores intervenientes à oferta hídrica superficial e à demanda hídrica, segundo a narrativa de cenários tendenciais de propagação dos padrões históricos de evolução destes fatores e a narrativa de cenários alternativos. Esta análise é feita através de um balanço hídrico entre disponibilidade hídrica e demanda hídrica. Esta proposta metodológica é aplicada sobre a região de abrangência da UGRHI do Tietê-Jacaré, e esta aplicação objetiva contribuir para a elaboração do plano da bacia da UGRHI em questão. Os fatores intervenientes à oferta hídrica superficial dizem respeito às variáveis meteorológicas, que influem diretamente no regime de precipitações, e aos padrões estatísticos históricos de evolução das precipitações. Os fatores intervenientes à demanda hídrica dizem respeito às variáveis sócio-econômicas e parâmetros tecnológicos de eficiência dos usos múltiplos dos recursos hídricos. Ambos os cenários, tendenciais e alternativos, narram a evolução destes fatores intervenientes à disponibilidade hídrica superficial e demanda hídrica nas dimensões climática e sócio-econômica. Na dimensão climática são propostos dois cenários de evolução dos fatores intervenientes à disponibilidade hídrica: o cenário climático tendencial (CCT) e o cenário climático alternativo. O cenário CCT é uma propagação futura dos padrões estatísticos históricos de evolução dos regimes de precipitações. Para este cenário são geradas séries sintéticas de precipitação, sobre a região ora em estudo, a partir da aplicação de um modelo estocástico linear. O cenário CCA leva em consideração os efeitos regionais das projeções de mudanças climáticas do cenário A1F (IPCC, 2000) para a região ora em estudo. Para este cenário são inferidos os efeitos da projeção de aumento da temperatura, sobre as séries geradas, através de relações empíricas regionais e conceituais de algumas variáveis meteorológicas que influem sobre o comportamento do regime de precipitações. Para a estimativa da disponibilidade hídrica superficial, segundo os dois cenários climáticos supracitados, foi usado o modelo HEC-HMS 2.1 (USACE) de modelagem e simulação de processos de chuva-vazão. Na dimensão sócio-econômica são propostos dois cenários de evolução dos fatores intervenientes à demanda hídrica: o cenário sócio-econômico tendencial (CSET) e o cenário sócio-econômico alternativo (CSEA). O cenário CSET é uma propagação futura dos padrões estatísticos históricos de evolução dos fatores sócio-econômicos e parâmetros tecnológicos intervenientes à demanda hídrica. O cenário CSEA leva em consideração os efeitos regionais das projeções de mudanças sócio-econômicas do cenário A1F (IPCC, 2000) para a região ora em estudo. Como ferramenta computacional para a estimativa de evolução dos fatores intervenientes à demanda hídrica foi desenvolvido, pelo autor dessa dissertação, o modelo MDSA ( Modelo de Demanda Setorial por Recursos Hídricos) baseado na metodologia do modelo NoWUM (Nordeste Water Use Model) (GAISER, T. et al., 2003). O resultado principal deste trabalho de dissertação foi obtido quando da comparação entre os cenários de disponibilidade hídrica superficial e demanda hídrica. Para todos os cenários comparativos foi constatada a evolução para uma situação crítica da relação entre disponibilidade hídrica superficial e demanda hídrica, principalmente nos períodos de estiagem de chuvas, ou períodos de recessão dos escoamentos superficiais. A ocorrência futura da situação crítica, ou escassez hídrica, varia de acordo com a maior ou menor pressão sobre os recursos hídricos, de acordo com os cenários sócio-econômicos, e de acordo com uma disponibilidade maior ou menor de chuvas sobre a região ora em estudo, de acordo com os cenários climáticos. Embora se possa esperar e seja evidente, de forma intuitiva, a ocorrência da escassez hídrica, a proposta, deste trabalho de dissertação, é a elaboração de uma metodologia, ou conjunto de métodos, para a estimativa quantitativa das variáveis de oferta e disponibilidade e demanda hídrica em todas as dimensões espacial e temporal.This work aims a methodological proposal for the analysis of future scenarios of surface water availability and water demand, being taken into consideration the evolution of the intervening factors of surface water availability and water demand, according to the narrative of trend scenarios of propagation of the historical standards, and the narrative of alternative scenarios. This methodological proposal is applied on the region of the UGRHI of Tietê-Jacaré, and this objective application is to contribute for the elaboration of the watershed plan of the UGRHI. The intervening factors to superficial water availability concern to the meteorological variables that influence directly in the precipitation regimen and to the historical statistical standards of evolution of precipitations. The intervening factors to the water demand concern to the socioeconomic variables and technological parameters of efficiency of the multiple uses of the water resources. Both scenarios, trend and alternative, tell the evolution of these intervening factors into the superficial water availability and water demand in the climatic and socioeconomic dimensions. In the climatic dimension two scenarios of evolution of the intervening factors to the water availability are considered: the climatic tendency scenario (CCT) and the climatic alternative scenario (CCA). The scenario CCT is a future propagation of the historical statistical standards of evolution of regimes of precipitations. For this scenario synthetic precipitation series are generated, on the region in study, from the application of a linear stochastic model. The scenario CCA takes in consideration the regional effect of the projections of climatic changes of scenario A1F (IPCC, 2000) for the region in study. For this scenario the effect of the projection of increase of the temperature are inferred, on the generated series, through regional and conceptual empirical relations of some meteorological variables that influence on the behavior of the precipitation behavior. For the estimate of the superficial water availability, according to two above-mentioned climatic scenarios, the model HEC-HMS 2,1 (USACE) of modeling and simulation of hydrological processes was used. In the socioeconomic dimension two scenarios of evolution of the intervening factor to the water demand are considered: the tendency socioeconomic scenario (CSET) and alternative socioeconomic scenario (CSEA). Scenario CSET is a future propagation of the historical statistical standards of evolution of the socioeconomic factors and intervening technological parameters to the water demand. Scenario CSEA takes in consideration the regional affect of the projections of socioeconomic changes of scenario A1F (IPCC, 2000) for the region in study. As a computational tool for the estimate of the evolution of the intervening factors to the water demand it was developed the MDSA model (Model of Sectorial Demand for Water Resources) based in the methodology of the NoWUM model (Northeast Water Use Model) (GAISER, T. et al.). The main result of this work was gotten when of the comparison between the scenarios of superficial water availability and water demand. For all the comparative scenarios were evidenced the evolution for a critical situation of the relation between superficial water availability and water demand, mainly in the periods of no rains, or periods of contraction of the superficial drainings. The future occurrence of the critical situation, or water scarcity, varies in accordance to the greater or minor pressure on the water resources, in accordance with the socioeconomic scenarios, and in accordance with a bigger or lesser availability of rains on the region in study, in accordance with the climatic scenarios. Although if it can wait and either evident the occurrence of the water scarcity, the proposal, of this work, is the elaboration of a methodology, or set of methods, for the quantitative estimate of the variable of availability and water demand in all the space and temporal dimensions.
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Snyder, Brett W. "Tools and Techniques for Evaluating the Reliability of Cloud Computing Systems." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1371685877.
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Schick, James Henry. "The Virginia Beef Cattle Simulation Model: A bio-economic simulation program modeling the interactions among reproduction, forage availability, nutrition, growth, and marketing in beef cattle." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/37628.
Анотація:
The Virginia Beef Cattle Simulation Model (VBCSM) is a user-friendly, dynamic, stochastic computer program whose objective is to serve as a decision-aid for Virginia cattlemen dealing with complex management issues such as whether to retain weaned calves through the stocker growth stage. Its five source-code modules are reproduction, forage, nutrition, marketing, and a tool that randomly assigns values to variables from appropriate statistical distributions. The VBCSM contains production statistics for 12 breeds, 21 forage species, and three Virginia agro-ecological zones. It simulates at the animal level using information obtained from program dialog. Help can be activated on each dialog page. It is event-driven on a daily time increment. The reproduction module simulates puberty, conception, abortion, parturition, dystocia, lactation, pregnancy testing, culling, within-herd replacement female selection, open or pregnant replacement female purchases, cow and calf mortality, and weaning. The forage module simulates daily pasture growth dependent upon month, precipitation, erosion, pasture maintenance, grazing system, farm location, weed infestation, and slope. This module interacts with the nutrition module to calculate each animalâ s forage intake, supplemental feed requirements, and daily gain or loss using National Research Council equations. The marketing routine sells the weanling calves to the stocker herd and sells stocker calves, orphan calves, and cull cows through user-specified markets, including the Virginia Tel-O-Market auction. After simulating for eight years to achieve equilibrium conditions, the VBCSM provides an income statement for the cow-calf operation and a partial budget for net income or loss from the stocker herd for up to three years. VBCSM was rigorously tested using a mathematical model with two calving seasons, three lengths of breeding season, four culling policies, and a year effect. Descriptive statistics suggest that the program code works in a consistent manner. However, several potential programming inconsistencies were discovered. Simulation results indicate that fall calving may be more profitable for Virginia cattle producers than spring calving for weanling calf production, but a spring calved stocker program may be more profitable that a fall calved stocker program. Perhaps, VBCSM will help cattlemen to enhance their profits by more efficient market planning and utilization of production resources.Ph. D.
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MATOS, JÚNIOR Rubens de Souza. "Identification of Availability and Performance Bottlenecks in Cloud Computing Systems: an approach based on hierarchical models and sensitivity analysis." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18702.
Анотація:
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CAPES
Cloud computing paradigm is able to reduce costs of acquisition and maintenance of computer systems, and enables the balanced management of resources according to the demand. Hierarchical and composite analytical models are suitable for describing performance and dependability of cloud computing systems in a concise manner, dealing with the huge number of components which constitute such kind of system. That approach uses distinct sub-models for each system level and the measures obtained in each sub-model are integrated to compute the measures for the whole system. Identification of bottlenecks in hierarchical models might be difficult yet, due to the large number of parameters and their distribution among distinct modeling levels and formalisms. This thesis proposes methods for evaluation and detection of bottlenecks of cloud computing systems. The methodology is based on hierarchical modeling and parametric sensitivity analysis techniques tailored for such a scenario. This research introduces methods to build unified sensitivity rankings when distinct modeling formalisms are combined. These methods are embedded in the Mercury software tool, providing an automated sensitivity analysis framework for supporting the process. Distinct case studies helped in testing the methodology, encompassing hardware and software aspects of cloud systems, from basic infrastructure level to applications that are hosted in private clouds. The case studies showed that the proposed approach is helpful for guiding cloud systems designers and administrators in the decision-making process, especially for tune-up and architectural improvements. It is possible to employ the methodology through an optimization algorithm proposed here, called Sensitive GRASP. This algorithm aims at optimizing performance and dependability of computing systems that cannot stand the exploration of all architectural and configuration possibilities to find the best quality of service. This is especially useful for cloud-hosted services and their complex underlying infrastructures.
O paradigma de computação em nuvem é capaz de reduzir os custos de aquisição e manutenção de sistemas computacionais e permitir uma gestão equilibrada dos recursos de acordo com a demanda. Modelos analíticos hierárquicos e compostos são adequados para descrever de forma concisa o desempenho e a confiabilidade de sistemas de computação em nuvem, lidando com o grande número de componentes que constituem esse tipo de sistema. Esta abordagem usa sub-modelos distintos para cada nível do sistema e as medidas obtidas em cada sub-modelo são usadas para calcular as métricas desejadas para o sistema como um todo. A identificação de gargalos em modelos hierárquicos pode ser difícil, no entanto, devido ao grande número de parâmetros e sua distribuição entre os distintos formalismos e níveis de modelagem. Esta tese propõe métodos para a avaliação e detecção de gargalos de sistemas de computação em nuvem. A abordagem baseia-se na modelagem hierárquica e técnicas de análise de sensibilidade paramétrica adaptadas para tal cenário. Esta pesquisa apresenta métodos para construir rankings unificados de sensibilidade quando formalismos de modelagem distintos são combinados. Estes métodos são incorporados no software Mercury, fornecendo uma estrutura automatizada de apoio ao processo. Uma metodologia de suporte a essa abordagem foi proposta e testada ao longo de estudos de casos distintos, abrangendo aspectos de hardware e software de sistemas IaaS (Infraestrutura como um serviço), desde o nível de infraestrutura básica até os aplicativos hospedados em nuvens privadas. Os estudos de caso mostraram que a abordagem proposta é útil para orientar os projetistas e administradores de infraestruturas de nuvem no processo de tomada de decisões, especialmente para ajustes eventuais e melhorias arquiteturais. A metodologia também pode ser aplicada por meio de um algoritmo de otimização proposto aqui, chamado Sensitive GRASP. Este algoritmo tem o objetivo de otimizar o desempenho e a confiabilidade de sistemas em cenários onde não é possível explorar todas as possibilidades arquiteturais e de configuração para encontrar a melhor qualidade de serviço. Isto é especialmente útil para os serviços hospedados na nuvem e suas complexas
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Barbieri, Pietro. "Can the availability of mineral nutrient be an obstacle to the development of organic agriculture at the global scale ?" Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0432.
Анотація:
L’agriculture biologique (AB) est souvent présentée comme une alternative prometteuse à l’agriculture conventionnelle, permettant des systèmes alimentaires durables tout en minimisant les impacts environnementaux. La capacité de l’AB à satisfaire la demande alimentaire mondiale reste néanmoins fortement débattue. Plusieurs études ont conclu que l’AB pourrait satisfaire la demande alimentaire globale à condition de réduire simultanément la consommation de produits animaux et les gaspillages. Cependant, ces études n’ont pas pleinement pris en compte les changements d’assolement et de choix d’espèces lorsque les systèmes conventionnels sont convertis en AB. Surtout, ils ont ignoré le rôle clé de la disponibilité en azote (N) dans le maintien des rendements en AB. Dans cette étude, nous avons d’abord réalisé une méta-analyse comparant les rotations de cultures en agriculture biologique et conventionnelle à l’échelle mondiale. Sur la base de ces résultats, nous avons développé une cartographie des espèces cultivées à l’échelle globale sous un scénario de fort développement de l’AB. Nous avons ensuite estimé la production alimentaire grâce au développement de GOANIM (Global Organic Agriculture NItrogen Model), un modèle biophysique et spatialement explicite d’optimisation linéaire simulant le cycle de l’azote (N) et ses effets sur la production alimentaire globale. GOANIM est adapté au cas de l’AB et simule les flux d'azote entre les terres cultivées, les animaux d'élevage et les prairies permanentes, ainsi qu’entre les systèmes agricoles biologiques et conventionnels. Le modèle optimise les populations d’élevage à l’échelle locale afin de maximiser l’approvisionnement en N provenant du fumier, ce qui maximise la production issue des terres cultivées, tout en minimisant la concurrence exercée par les animaux pour les ressources alimentaires. GOANIM a été utilisé pour simuler l’offre alimentaire sous plusieurs scénarios de conversion à l’AB. Ces résultats ont été comparés à différentes estimations de la demande alimentaire mondiale. Nous montrons que la carence en N risque d’être un facteur limitant majeur de la production en AB, entraînant une réduction de -37% de la disponibilité alimentaire à l’échelle globale sous un scénario de conversion à l’AB de 100%. Nous montrons que des taux de conversions inférieurs (jusqu'à 60% des terres agricoles), en coexistence avec l'agriculture conventionnelle, permettent de satisfaire la demande alimentaire mondiale si cette conversion est associée à une évolution conjointe de la demande, telle que la réduction de l'apport énergétique par individu ou du gaspillage alimentaire. Ces travaux contribuent de manière substantielle à mieux comprendre le rôle que l’AB peut jouer dans la transition vers des systèmes alimentaires équitables et durables. Ils indiquent également des voies à suivre pour parvenir à la sécurité alimentaire mondialeOrganic agriculture is often proposed as a promising approach to achieve sustainable food systems while minimizing environmental impacts. Its capacity to meet the global food demand remains, however, debatable. Some studies have investigated this question and have concluded that organic farming could satisfy the global food demand provided that animal product consumption and food waste are reduced. However, these studies have not fully considered the changes in the type of crops grown that occur when conventional farming systems are converted to organic farming. Most importantly, they also have missed a critical ecological phenomenon by not considering the key role that nitrogen (N) cycling plays in sustaining crop yields in organic farming. In this study, we first carried out a global meta-analysis comparing organic vs conventional crop rotations. Based on these results, we developed global spatial explicit maps of the type of crop grown if organic farming was to drastically expand. We then estimated organic global food production using GOANIM (Global Organic Agriculture NItrogen Model), a spatially explicit, biophysical and linear optimization model simulating N cycling in organically managed croplands and its feedback effects on food production. GOANIM explores N flows between croplands, livestock animals and permanent grasslands, and with conventional farming systems. The model optimizes livestock populations at the local scale in order to maximize N supply from livestock manure – hence maximizing cropland production –, while minimizing the animals’ competition for grain food resources. We used GOANIM to simulate several supply-side scenarios of global conversion to organic farming. We then compared the outcomes of these scenarios with different estimates of the global demand, thus leading to complete exploration of the global production-demand options space. We show N deficiency would be a major limiting factor to organic production in a full organic world, leading to an overall -37% reduction in global food availability. Nevertheless, we also show that lower conversion shares (up to 60%) would be feasible in coexistence with conventional farming when coupled with demand-side solutions, such as reduction of the per capita energy intake or food wastage. This work substantially contributes to advancing our understanding of the role that organic farming may play to reach fair and sustainable food systems, and it indicates future pathways for achieving global food security
43
Hublart, Paul. "Exploring the use of conceptual catchment models in assessing irrigation water availability for grape growing in the semi-arid Andes." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS181.
Анотація:
La thèse explore l’utilisation de modèles hydrologiques globaux pour estimer la disponibilité en eau agricole dans le contexte des Andes chiliennes semi-arides. Dans cette région, l’approvisionnement en eau des cultures irriguées de fonds de vallée durant l’été dépend de précipitations se produisant sous forme de neige à haute altitude lors de quelques évènements hivernaux. L’influence des phénomènes ENSO et PDO induit par ailleurs une forte variabilité climatique à l’échelle inter-annuelle, marquée par l’occurrence d’années extrêmement sèches ou humides. La région connaît aussi depuis les années 1980 une progression importante de la viticulture irriguée. Afin de prendre en compte les variations saisonnières et inter-annuelles de la disponibilité et de la consommation en eau d’irrigation, une chaîne de modélisation intégrée a été développée et différentes méthodes de quantification/réduction des incertitudes de simulation ont été mises en œuvre. Les écoulements naturels ont été simulés avec un modèle hydrologique global de type empirique/conceptuel prenant en compte les processus d’accumulation et d’ablation de la neige. En parallèle, les besoins en eau d’irrigation ont été estimés à l’échelle du bassin à partir de modèles phénologiques orientés processus et d’une approche simple du bilan hydrique du sol. Dans l’ensemble, une approche holistique et parcimonieuse a été privilégiée afin de maintenir un niveau d’abstraction mathématique et de représentation des processus équivalent à celui des modèles de bassin couramment utilisés. Afin d’améliorer l’utilité et la fiabilité des simulations obtenues en contexte de changement ou de forte variabilité climatique, l’effet des températures extrêmes sur le développement des cultures et l’impact des pertes en eau par sublimation à haute altitude ont fait l’objet d’une attention particulière. Ce cadre de modélisation conceptuel a été testé pour un bassin typique des Andes semi-arides (1512 km2, 820–5500 m a.s.l.) sur une période de 20 ans incluant une large gamme de conditions climatiques et des pratiques agricoles non-stationnaires (évolution des variétés de vigne, des surfaces et modes d’irrigation, etc). L’évaluation des modèles a été réalisée dans un cadre bayésien en faisant l’hypothèse d’erreurs auto-corrélées, hétéroscédastiques et non-gaussiennes. Différents critères et sources de données ont par ailleurs été mobilisés afin de vérifier l’efficacité et la cohérence interne de la chaîne de modélisation ainsi que la fiabilité statistique et la finesse des intervalles de confiance obtenus. De manière alternative, une caractérisation des erreurs de structure et de l’ambiguïté propre au choix du modèle hydrologique a été réalisée de manière non-probabiliste à partir d’une plate-forme de modélisation modulaire. Dans l’ensemble, la prise en compte explicite de la consommation en eau des cultures a mis en valeur certaines interactions entre paramètres hydrologiques et permis d’améliorer la fiabilité des simulations hydrologiques en année sèche. Finalement, une étude de sensibilité à différents seuils d’augmentation de la température et de la concentration en CO2 a été effectuée afin d’évaluer l’impact potentiel des changements climatiques sur le comportement de l’hydrosystème et la capacité à satisfaire la demande en eau d’irrigation dans le futurThis thesis investigates the use of lumped catchment models to assess water availability for irrigation in the upland areas of northern-central Chile (30°S). Here, most of the annual water supply falls as snow in the high Cordillera during a few winter storms. Seasonal snowpacks serve as natural reservoirs, accumulating water during the winter and sustaining streams and aquifers during the summer, when irrigation demand in the cultivated valleys is at its peak. At the inter-annual timescale, the influence of ENSO and PDO phenomena result in the occurrence of extremely wet and dry years. Also, irrigated areas and grape growing have achieved a dramatic increase since the early 1980s. To evaluate the usefulness of explicitly accounting for changes in irrigation water-use in lumped catchment models, an integrated modeling framework was developed and different ways of quantifying/reducing model uncertainty were explored. Natural streamflow was simulated using an empirical hydrological model and a snowmelt routine. In parallel, seasonal and inter-annual variations in irrigation requirements were estimated using several process-based phenological models and a simple soil-water balance approach. Overall, this resulted in a low-dimensional, holistic approach based on the same level of mathematical abstraction and process representation as in most commonly-used catchment models. To improve model reliability and usefulness under varying or changing climate conditions, particular attention was paid to the effects of extreme temperatures on crop phenology and the contribution of sublimation losses to water balance at high elevations. This conceptual framework was tested in a typical semi-arid Andean catchment (1512 km2, 820–5500 m a.s.l.) over a 20–year simulation period encompassing a wide range of climate and water-use conditions (changes in grape varieties, irrigated areas, irrigation techniques). Model evaluation was performed from a Bayesian perspective assuming auto-correlated, heteroscedastic and non-gaussian residuals. Different criteria and data sources were used to verify model assumptions in terms of efficiency, internal consistency, statistical reliability and sharpness of the predictive uncertainty bands. Alternatively, a multiple-hypothesis and multi-criteria modeling framework was also developed to quantify the importance of model non-uniqueness and structural inadequacy from a non-probabilistic perspective. On the whole, incorporating the effects of irrigation water-use led to new interactions between the hydrological parameters of the modeling framework and improved reliability of streamflow predictions during low-flow periods. Finally, a sensitivity analysis to changes in climate conditions was conducted to evaluate the potential impacts of increasing temperatures and atmospheric CO2 on the hydrological behavior of the catchment and the capacity to meet future water demands
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Mayer, Tobias Rene. "Achieving collaboration in distributed systems deployed over selfish peers." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00961233.
Анотація:
Today's networks are often characterized by a free aggregation of independent nodes. Thus, the possibility increases that a selfish party operates a node, which may violate the collaborative protocol in order to increase a personal benefit. If such violations differ from the system goals they can even be considered as attack. Current fault-tolerance techniques may weaken the harmful impact to some degree but they cannot always prevent them. Furthermore, the several architectures differ in their fault-tolerance capabilities. This emphasizes the need for approaches able to achieve collaboration from selfish nodes in distributed systems. In this PhD thesis, we consider the problem of attaining a targeted level of collaboration in a distributed architecture deployed over rational selfish nodes. They have interest in deviating from the collaborative protocol to increase a personal benefit. In order to cover a broad spectrum of systems, we do not modify the collaborative protocol itself. Instead, we propose to add a monitoring logic to inspect the correctness of a node's behaviour. The designer of the monitoring system is faced with a complex and dynamic situation. He needs to consider aspects such as the specific circumstances (e.g. message traffic), the inspection effort or the node's individual preferences. Furthermore, he should consider that each agent could be aware of the other agents' preferences as well as selfishness and perform strategic choices consequently. This complex and interdependent setup corresponds to a class of Game Theory (GT) known as Inspection Games (IG). They model the general situation where an inspector verifies through inspections the correct behaviour of another party, called inspectee. However, inspections are costly and the inspector's resources are limited. Hence, a complete surveillance is not possible and an inspector will try to minimize the inspections. In this thesis, the initial IG model is enriched by the possibility that a violation is not detected during an inspection (false negatives). Applied to distributed systems, the IG is used to model the network participants' strategy choice. As outcome, it enables to calculate system parameters to attain the desired collaboration value. The approach is designed as generic framework. It can be therefore applied to any architecture considering any selfish goal and any reliability technique. For the sake of concreteness, we will discuss the IG approach by means of the illustrative case of a Publish/Subscribe architecture. The IG framework of this thesis secures the whole collaborative protocol by a monitoring approach. This represents a new way in terms of reliability mechanisms. The applicability is furthermore supported by the software library RCourse. Simplifying robustness evaluations of distributed systems, it is suitable for model verification and parameter calibration.
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Sudnick, Madeline Cassidy. "Nature and nurture: the influence of environmental conditions and parental care on avian offspring development." Ohio University Honors Tutorial College / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1619025814154044.
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Moura, Eulina Maria de. "Avalia??o da disponibilidade h?drica e da demanda h?drica no trecho do Rio Piranhas-A?u entre os a?udes Coremas-m?e D??gua e Armando Ribeiro Gon?alves." Universidade Federal do Rio Grande do Norte, 2007. http://repositorio.ufrn.br:8080/jspui/handle/123456789/16018.
Анотація:
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Previous issue date: 2007-03-26Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
Piranhas-A?u basin is a Federal watershed with a drainage area of 43.681,5 km2, sited at Brazilian northeast semi arid, with 60% of your area in Paraiba State and 40% in Rio Grande do Norte State. The main river, Piranhas-A?u, has strategic importance for development of these states, because it s an essential source for many socio-economics activities developed along watercourse. The river s reach between Coremas-M?e D`?gua Dam and Armando Ribeiro Gon?alves Dam has many irrigation projects, and supply many riverside cities. All this activities practiced in this river s reach consumes high water volumes. Due the importance of this stream and the necessity of an adequate management, this work aims for an impartial and detailed evaluation of real water supply conditions in this river s reach, by the application of hydrological modeling, including the arrangement of main dams in tributaries, and storage reservoir water balance. The rainfall-discharge model s applied in each sub-basins it was selected the model MODHISA- Hydrological Model of Semi Arid, that is a concentrated model with easy application. The simulation produced 50 years of inflows into the reservoirs, for which, were constructed the guaranties curves; and produced 50 years of synthetic discharge data in relevant points on the river and on its affluents; so it was constructed the permanence curves. Confronting the available discharge with the current and futures volumes of raw water captured in this river s reach, it was verified that de demands have high guaranties. This work concluded that the MODHISA Model is suitable to reproduce the hydrologic characteristics of Piranhas-A?u sub-basins, and showing good results
A Bacia Hidrogr?fica do Rio Piranhas-A?u ? uma bacia Federal de 43.681,5 Km2, localizada no Semi-?rido nordestino, com 60% da sua ?rea no Estado da Para?ba e 40% no Estado do Rio Grande do Norte. Seu curso d ?gua principal, o rio Piranhas-A?u, tem import?ncia estrat?gica para o desenvolvimento desses dois Estados, pois ? um manancial vital para in?meras atividades s?cio-econ?micas realizadas ao longo do seu curso. O trecho compreendido entre o a?ude Coremas-M?e D`?gua (PB) e o a?ude Armando Ribeiro Gon?alves (RN) possui diversos sistemas adutores, projetos de irriga??o, e abastece v?rias cidades ribeirinhas. Todas essas atividades realizadas no trecho do rio v?m demandando elevado volume de ?gua. Diante da import?ncia desse manancial e da necessidade de implanta??o de uma gest?o adequada, esse trabalho tem como objetivo realizar um levantamento minucioso e imparcial das condi??es reais de oferta de ?gua desse trecho do rio Piranhas-A?u, atrav?s da modelagem hidrol?gica que incluir? a disposi??o dos principais a?udes das bacias de contribui??o do rio, e o balan?o h?drico mensal destes. O modelo chuva-vaz?o aplicado nas sub-bacias foi o MODHISA- Modelo Hidrol?gico para o Semi-?rido, que ? um modelo concentrado e de f?cil aplica??o. A simula??o da transforma??o da precipita??o m?dia ocorrida nas sub-bacias em defl?vios afluentes ao rio Piranhas-A?u gerou 50 anos de dados sint?ticos de vaz?o afluente aos principais a?udes, para os quais foram constru?das as curvas de garantia; e gerou 50 anos de dados de vaz?o sint?tica em pontos relevantes do rio Piranhas-A?u e de seus afluentes, possibilitando a constru??o das curvas de perman?ncia das vaz?es ao longo do trecho estudado. Ao confrontar as vaz?es dispon?veis com as demandas atuais e futuras de capta??o de ?gua bruta do trecho, observou-se que as garantias de atendimento s?o elevadas, j? que a porcentagem de perman?ncia destas no trecho do rio ? alta. Concluiu-se tamb?m que o MODHISA apresentou boa adequa??o ?s caracter?sticas hidrol?gicas das sub-bacias contribuintes do rio Piranhas-A?u e seus afluentes; tornando-se uma ferramenta de f?cil aplica??o e de bons resultados
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Durigon, Angelica. "Mecanismos de transferência de água entre solo, planta e atmosfera e sua relação com o estresse hídrico vegetal." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/11/11131/tde-20102011-101032/.
Анотація:
Parametrizações mecanísticas descrevem fisicamente a interação das plantas com o ambiente baseando-se em processos fundamentais, como assimilação de líquida de CO2 e extração da água do solo pelas raízes, influenciados pelas condições do ambiente. O objetivo principal dessas rotinas é aumentar o entendimento do sistema estudado pela integração quantitativa e qualitativa do conhecimento em um modelo de simulação dinâmica do sistema real. Definindo estresse hídrico como a condição em que uma planta aumenta a resistência estomática em conseqüência do aumento da demanda atmosférica e/ou da redução da disponibilidade hídrica no solo, tem-se como hipótese que o déficit hídrico em plantas é causado por fatores ambientais relacionados com as interfaces solo-raiz e folha-atmosfera. O objetivo geral desse estudo é identificar quais são as variáveis do solo e da atmosfera determinantes e que devem ser consideradas na modelagem da deficiência hídrica em plantas. Os teores de água no solo e na atmosfera foram monitorados em condições de campo durante o desenvolvimento da cultura de feijão (Phaseolus vulgaris L.) entre Junho e Setembro de 2010, e correlacionados ao estresse hídrico caracterizado por medições de temperatura do dossel. As variáveis de interesse, especificamente o potencial matricial da água do solo, a temperatura e a umidade do ar e a temperatura do dossel foram medidas regularmente em intervalos de 30 minutos. A taxa de transpiração e a condutância estomática foram medidas ocasionalmente. Uma parcela foi irrigada durante todo o ciclo da cultura (tratamento totalmente irrigada), enquanto a outra foi submetida ao estresse hídrico na fase reprodutiva (tratamento com déficit de irrigação). A metodologia utilizada neste estudo deu suporte à hipótese inicial. Os principais fatores relacionados à interface solo-raiz são as propriedades hidráulicas do solo, especialmente a condutividade hidráulica e da densidade de comprimento radicular; na interface atmosfera de folhas, os fatores mais importantes são o déficit de pressão de vapor do ar atmosférico VPD. Estes fatores devem ser considerados de alguma forma na modelagem estresse hídrico em plantas. A detecção da ocorrência de estresse hídrico nas plantas no tratamento com déficit de irrigação foi feito por comparações entre o VPD e diferença de temperatura entre o dossel e o ar tdossel-ar e entre tdossel e a temperatura do bulbo úmido twb dos dois tratamentos hídricos. O início do estresse hídrico nas plantas com déficit de irrigação ocorreu em 05 de Agosto. As simulações com os modelos mecanísticos de extração da água do solo pelas raízes proposto por Jong van Lier et al. (2008) e de assimilação de CO2 proposto por Jacobs (1994) foram feitos com os dados de ambos os tratamentos. O modelo de extração foi sensível aos parâmetros hidráulicos do solo, especialmente a condutividade hidráulica e o comprimento radicular. A taxa de transpiração estimada pelo modelo de Jacobs (1994) mostrou-se dependente da temperatura do dossel utilizada para calcular o déficit de umidade específica folha-ar Ds e a condutância do mesofilo, do próprio Ds (dependente também da temperatura do ar), e do índice de área foliar.Mechanistic parameterizations describe physically the interactions between crop and environment based on primary processes such as CO2 net assimilation and root water uptake from soil and how they are influenced by environmental conditions. An important purpose of developing mechanistic routines is to improve the understanding of a system by qualitative and quantitative integration of knowledge in a dynamic simulation model of a real system. Defining water stress as the condition in which stomatal resistance of plant leaves increases as a consequence of enhanced atmospheric demand and/or reduced soil water availability, the investigated hypothesis was that plant water stress is caused by environmental factors related to both the soilroot and leave-atmosphere interfaces. The main objective of the research was to identify which atmosphere and soil parameters are determinant and must be considered in crop water stress modeling. Soil and atmosphere water content were monitored under field conditions during the growing season of a Common Bean (Phaseolus vulgaris L.) crop between June and September, 2010, and correlated to plant water stress characterized by measurements of canopy temperature. The variables of interest, specifically the soil water pressure head, air temperature and humidity and canopy temperature were measured regularly at short intervals. Transpiration rate and stomatal conductance were measured occasionally. One plot was irrigated during the whole crop cycle (fully irrigated treatment), while the other one was subject to water stress in the reproductive phase (deficit irrigated treatment). The methodology used in this study supported the initial hypothesis. The main soil-root interface related factors that determine water stress are the soil hydraulic properties, especially the hydraulic conductivity, and the root length density; at the leaf atmosphere interface, the most important factor is the vapor pressure deficit of atmospheric air VPD. These factors must be somehow considered in crop water stress modeling. The detection of water stress occurrence in the deficit irrigated plants was made by comparisons between VPD and temperature difference between canopy and air tcanopy-air and between tcanopy and wet bulb temperature twb of the two irrigation treatments. The onset of water stress in deficit irrigated plants occurred on August 5. The simulations with the mechanistic models of soil water root uptake proposed by Jong van Lier et al. (2008) and of CO2 assimilation by Jacobs (1994) were made with data from the two treatments. The soil water uptake model was sensitive to soil hydraulic parameters, especially hydraulic conductivity and root length density. The transpiration rate estimated by the Jacobs (1994) model showed to be dependent on the canopy temperature used to calculate the specific humidity deficit between leaves and air Ds and the mesophyll conductance, on Ds (on its turn also dependent on air temperature), and on the leaf area index
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Assunção, Argos Willian de Almeida. "Cinética e variação molecular de substâncias húmicas formadas da lixiviação de macrófitas aquáticas." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/7128.
Анотація:
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
The humic substances (HS) are important to aquatic ecosystems. In this study we investigated the kinetics and molecular variations of dissolved fulvic acids (FA) and humic acids (HA) formed from aquatic macrophytes decomposition under aerobic and anaerobic conditions. The results supported the proposition and validation of kinetic models that treated the formation, transformation and mineralization of dissolved SH. Although mineralization and humification are concurrent events, the aerobic condition favored these two processes contributed primarily to HA formation. The detritus showed different mineralization and HS formation potentials. Larger amounts of HS were related to higher carbon content in the detritus and lower mineralization of dissolved organic carbon (DOC). The SH mass loss rates were lower than the refractory fraction of particulate detritus, showing the recalcitrance of dissolved HS. The DOC with higher C/N proportions presented higher coefficient rates. The HS presented similar characteristics regardless of detritus source. However, aerobic conditions favored variation of polysaccharides content in HS, indicating transformation of these compounds. Aerobic conditions favored dissolved HS mineralization and its assimilation by microorganisms. The AH presented higher reactive fraction than FA, and was an important precursor of FA. The FA presented refractory characteristics and formed less HA, indicating that the liginocellulosic compounds of the detritus are the main precursors of HA.
As substâncias húmicas (SH) são de grande importância para os ecossistemas aquáticos. Nesse estudo investigaram-se a cinética e a variação molecular de ácidos fúlvicos (AF) e húmicos (AH) dissolvidos formados da degradação de macrófitas aquáticas, em condições aeróbias e anaeróbias. Os resultados subsidiaram a proposição e validação de modelos cinéticos que trataram da formação, transformação e mineralização das SH dissolvidas. Embora a mineralização e a humificação sejam eventos concorrentes, a condição aeróbia favoreceu esses dois processos e contribuiu, principalmente, com a formação dos AH. Os detritos apresentaram diferentes potencias de mineralização e formação de SH dissolvidas. As maiores quantidades de SH foram relacionadas com o maior teor de carbono no detrito e menor degradação do carbono orgânico dissolvido (COD). Os coeficientes de perda de massa das SH foram inferiores aos da fração refratária particulada dos detritos, evidenciando a recalcitrância das SH dissolvidas. O COD apresentou coeficientes de mineralização maiores nos meios com relações C/N maiores. As SH apresentaram características semelhantes independentemente da origem do detrito. Entretanto, houve variações maiores de polissacarídeos em condição aeróbia, indicando que houve maior transformação desses compostos nessa condição. Os ambientes aeróbios favoreceram a degradação das SH dissolvidas e a incorporação pelos microrganismos. O AH apresentou maior fração reativa que o AF e, por conseguinte, foi indicado como potencial precursor de AF. Os AF apresentaram características mais refratárias e formaram menos AH, indicando que os compostos lignocelulósicos dos detritos foram os principais precursores dos AH.
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Gimenez, Audrey. "Etude des interactions entre diazotrophie, disponibilité nutritive et production planctonique dans l'océan de surface du pacifique tropical sud-ouest par une approche combinant observation et modélisation." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0208/document.
Анотація:
Ce travail s'inscrit dans le cadre du projet OUTPACE visant à caractériser les eaux du Pacifique tropical Sud-Ouest (WTSP) en termes de stocks et flux biogéochimiques, et de diversité biologique des diazotrophes le long d'un transect longitudinal Ouest-Est. Il est le fruit de la combinaison étroite de deux approches, l'une expérimentale et l'autre basée sur la modélisation, dans le but d'étudier le rôle de la diazotrophie dans la dynamique planctonique et les cycles biogéochimiques des eaux de surface du WTSP. Les analyses de plusieurs grandeurs mesurées lors de la campagne, et notamment la production primaire (PP) et du temps de turnover du phosphate inorganique dissous (DIP), ont permis d'observer un gradient Ouest-Est de productivité et de disponibilité nutritive, étroitement lié à la variabilité spatiale des taux de fixation de N$_2$. L'utilisation d'un modèle biogéochimique mécaniste (implémenté dans la plateforme Eco3M) incluant explicitement deux compartiments de diazotrophes, couplé à un modèle physique 1D vertical, a permis de mettre en évidence le fait que l'absence/présence de diazotrophie permettait d'expliquer le contraste observé entre les régions de l'Ouest de l'archipel Mélanésien (WMA) et de l'Ouest de la gyre du Pacifique Sud (WGY). Les résultats du modèle ont montré que les organismes non diazotrophes bénéficiaient de l'apport d'azote nouveau apporté par la fixation de N$_2$, et que la production planctonique de surface dépendait significativement de l'activité des diazotrophes, cette dernière contrôlée à l'Ouest par la disponibilité en phosphate et à l'Est par la disponibilité en ferThis work is part of the OUTPACE project which aimed to characterize the western tropical south Pacific (WTSP) in terms of biogeochemical stocks and fluxes and biological diversity of diazotrophs along a West-East longitudinal transect. This work combines an experimental with a modeling approach in order to study the role of diazotrophy in the planktonic dynamics and biogeochemical cycles of the WTSP surface waters. The values measured during the campaign, iespecially those of primary production (PP) and dissolved inorganic phosphate (DIP) turnover time, revealed a West-East gradient of productivity and nutrient availability, closely related to the spatial variability of N$_2$ fixation rates. The use of a mechanistic biogeochemical model (implemented in the Eco3M platform) explicitly including two compartments of diazotrophs and coupled with a vertical 1D physical model, allowed to highlight the fact that the absence / presence of diazotrophy could explain the contrast between the western regions of the Melanesian Archipelago (WMA) and the west of the south Pacific gyre (WGY). ). The model results showed that non-diazotrophic organisms benefited from the new nitrogen supply provided by nitrogen fixers, and that the surface planktonic production depended significantly on diazotroph activity, which is controlled by the phosphate availability in the west and by the iron availability in the east of the WTSP
50
Mayer, Tobias René. "Achieving collaboration in distributed systems deployed over selfish peers." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0083/document.
Анотація:
Les réseaux actuels sont souvent caractérisés par une intégration dynamique de nœuds étrangers. La possibilité qu’une entité dissidente égoïste exploite un nœud augmente alors, ce qui peut constituer une violation du protocole de collaboration en vue d’accroître un avantage personnel. Si de telles violations diffèrent des objectifs du système, elles peuvent même être considérées comme une attaque. Si des techniques de tolérance aux fautes existent pour affaiblir l’impact sur le système, celui-ci ne peut pas totalement se prémunir de ce type d’attaque. Cela justifie la nécessité d’une approche pour maintenir un degré de collaboration nœuds égoïstes dans les systèmes distribues. Dans cette thèse, nous considérons le problème d’atteindre un niveau ciblé de collaboration dans une architecture répartie intégrant des nœuds égoïstes, qui ont intérêt à violer le protocole de collaboration pour tirer parti du système. L’architecture et le protocole seront modifies le moins possible. Un mécanisme d’inspection de chaque nœud sera mis en place pour décider de la légitimité de ses interactions avec ses voisins. Le concepteur du système d’inspection est confronté avec une situation complexe. Il doit corréler plusieurs aspects tels que les circonstances particulières de l’environnement ou des préférences individuelles du nœud. En outre, il doit tenir compte du fait que les nœuds peuvent connaitre l’état de ses voisins et construire ses décisions en conséquence. La surveillance proposée dans cette thèse correspond à une classe de modèles de la théorie des jeux connus sous le nom « Inspection Game » (IG). Ils modélisent la situation générale où un « inspecteur » vérifie par des inspections du comportement correct d’une autre partie, appelée « inspectee ». Toutefois, les inspections sont coûteuses et les ressources de l’inspecteur sont limitées. Par conséquent, une surveillance complète n’est pas envisageable et un inspecteur tentera de minimiser les inspections. Dans cette thèse, le modèle initial IG est enrichi par la possibilité d’apparition de faux négatifs, c’est à dire la probabilité qu’une violation ne soit pas détectée lors d’une inspection. Appliqué sur des systèmes distribués, cette approche permet de modéliser les choix collaboratifs de chacun des acteurs (violer le protocole ou pas, inspecter ou pas). Comme résultat, le modèle IG retourne les paramètres du système pour atteindre le niveau de collaboration souhaité. L’approche est conçue comme un « framework ». Elle peut donc s’adapter à toutes les architectures et toutes les techniques de fiabilité. Cette approche IG sera présentée à l’aide d’un exemple concret d’architecture Publish/Subscribe. L’approche du jeu d’inspection de cette thèse pour objectif de sécuriser l’ensemble du protocole de collaboration. Ceci constitue un nouveau concept de mécanisme de fiabilité. [...]Today’s networks are often characterized by a free aggregation of independent nodes. Thus, the possibility increases that a selfish party operates a node, which may violate the collaborative protocol in order to increase a personal benefit. If such violations differ from the system goals they can even be considered as attack. Current fault-tolerance techniques may weaken the harmful impact to some degree but they cannot always prevent them. Furthermore, the several architectures differ in their fault-tolerance capabilities. This emphasizes the need for approaches able to achieve collaboration from selfish nodes in distributed systems. In this PhD thesis, we consider the problem of attaining a targeted level of collaboration in a distributed architecture deployed over rational selfish nodes. They have interest in deviating from the collaborative protocol to increase a personal benefit. In order to cover a broad spectrum of systems, we do not modify the collaborative protocol itself. Instead, we propose to add a monitoring logic to inspect the correctness of a node’s behaviour. The designer of the monitoring system is faced with a complex and dynamic situation. He needs to consider aspects such as the specific circumstances (e.g. message traffic), the inspection effort or the node’s individual preferences. Furthermore, he should consider that each agent could be aware of the other agents’ preferences as well as selfishness and perform strategic choices consequently. This complex and interdependent setup corresponds to a class of Game Theory (GT) known as Inspection Games (IG). They model the general situation where an inspector verifies through inspections the correct behaviour of another party, called inspectee. However, inspections are costly and the inspector’s resources are limited. Hence, a complete surveillance is not possible and an inspector will try to minimize the inspections. In this thesis, the initial IG model is enriched by the possibility that a violation is not detected during an inspection (false negatives). Applied to distributed systems, the IG is used to model the network participants’ strategy choice. As outcome, it enables to calculate system parameters to attain the desired collaboration value. The approach is designed as generic framework. It can be therefore applied to any architecture considering any selfish goal and any reliability technique. For the sake of concreteness, we will discuss the IG approach by means of the illustrative case of a Publish/Subscribe architecture. The IG framework of this thesis secures the whole collaborative protocol by a monitoring approach. This represents a new way in terms of reliability mechanisms. The applicability is furthermore supported by the software library RCourse. Simplifying robustness evaluations of distributed systems, it is suitable for model verification and parameter calibration