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1
Davis, Michael A. "Cloud-Radiative Feedback and Ocean-Atmosphere Feedback In the Southeast Pacific Ocean Simulated by IPCC AR4 GCMs." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313350254.
Повний текст джерела
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Ullah, Amjad. "Towards a novel biologically-inspired cloud elasticity framework." Thesis, University of Stirling, 2017. http://hdl.handle.net/1893/26064.
Повний текст джерелаАнотація:
With the widespread use of the Internet, the popularity of web applications has significantly increased. Such applications are subject to unpredictable workload conditions that vary from time to time. For example, an e-commerce website may face higher workloads than normal during festivals or promotional schemes. Such applications are critical and performance related issues, or service disruption can result in financial losses. Cloud computing with its attractive feature of dynamic resource provisioning (elasticity) is a perfect match to host such applications. The rapid growth in the usage of cloud computing model, as well as the rise in complexity of the web applications poses new challenges regarding the effective monitoring and management of the underlying cloud computational resources. This thesis investigates the state-of-the-art elastic methods including the models and techniques for the dynamic management and provisioning of cloud resources from a service provider perspective. An elastic controller is responsible to determine the optimal number of cloud resources, required at a particular time to achieve the desired performance demands. Researchers and practitioners have proposed many elastic controllers using versatile techniques ranging from simple if-then-else based rules to sophisticated optimisation, control theory and machine learning based methods. However, despite an extensive range of existing elasticity research, the aim of implementing an efficient scaling technique that satisfies the actual demands is still a challenge to achieve. There exist many issues that have not received much attention from a holistic point of view. Some of these issues include: 1) the lack of adaptability and static scaling behaviour whilst considering completely fixed approaches; 2) the burden of additional computational overhead, the inability to cope with the sudden changes in the workload behaviour and the preference of adaptability over reliability at runtime whilst considering the fully dynamic approaches; and 3) the lack of considering uncertainty aspects while designing auto-scaling solutions. This thesis seeks solutions to address these issues altogether using an integrated approach. Moreover, this thesis aims at the provision of qualitative elasticity rules. This thesis proposes a novel biologically-inspired switched feedback control methodology to address the horizontal elasticity problem. The switched methodology utilises multiple controllers simultaneously, whereas the selection of a suitable controller is realised using an intelligent switching mechanism. Each controller itself depicts a different elasticity policy that can be designed using the principles of fixed gain feedback controller approach. The switching mechanism is implemented using a fuzzy system that determines a suitable controller/- policy at runtime based on the current behaviour of the system. Furthermore, to improve the possibility of bumpless transitions and to avoid the oscillatory behaviour, which is a problem commonly associated with switching based control methodologies, this thesis proposes an alternative soft switching approach. This soft switching approach incorporates a biologically-inspired Basal Ganglia based computational model of action selection. In addition, this thesis formulates the problem of designing the membership functions of the switching mechanism as a multi-objective optimisation problem. The key purpose behind this formulation is to obtain the near optimal (or to fine tune) parameter settings for the membership functions of the fuzzy control system in the absence of domain experts’ knowledge. This problem is addressed by using two different techniques including the commonly used Genetic Algorithm and an alternative less known economic approach called the Taguchi method. Lastly, we identify seven different kinds of real workload patterns, each of which reflects a different set of applications. Six real and one synthetic HTTP traces, one for each pattern, are further identified and utilised to evaluate the performance of the proposed methods against the state-of-the-art approaches.
3
Kropf, Dorothy Cortez. "Applying UTAUT to Determine Intent to Use Cloud Computing in K-12 Classrooms." ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/5212.
Повний текст джерелаАнотація:
Although school districts provide collaborative cloud computing tools such as OneDrive and Google Drive for students and teachers, the use of these tools for grading and feedback purposes remains largely unexplored. Therefore, it is difficult for school districts to make informed decisions on the use of cloud applications for collaboration. This quantitative, nonexperimental study utilized Venkatesh et al.'s unified theory of acceptance and use of technology (UTAUT) to determine teachers' intent to use collaborative cloud computing tools. Online surveys with questions pertaining to UTAUT's predictor variables of performance expectancy (PE), effort expectancy (EE), social influence (SI), facilitating conditions (FC) and UTAUT's criterion variable of behavioral intent (BI) were administered to a convenience sample of 129 teachers who responded to an email solicitation. Pearson correlation results of r = 0.781, r = 0.646, r = 0.569, and r = 0.570 indicated strong, positive correlations between BI and PE, EE, SI, and FC respectively. Spearman rho correlations results of rs = 0.746, rs = 0.587, rs = 0.569, and rs = 0.613 indicated strong, positive correlations between BI and PE, EE, SI, and FC respectively. Simple linear regression results indicated that PE and EE are strong predictors of BI when moderated by age, gender, experience, and voluntariness of use (VU). SI is a strong predictor of BI when moderated by gender, but not by age, experience, and VU. This study's application of the UTAUT model to determine teachers' BI to use collaborative cloud computing tools could transform how administrators and educational technologists introduce these tools for grading and feedback purposes. This study contributes to the growing body of literature on technology integration among K-12 teachers.
4
Hygate, Alexander P. S. [Verfasser], and Diederik [Akademischer Betreuer] Kruijssen. "The Physics of Cloud-scale Star Formation and Feedback Across Cosmic Time / Alexander Philip Stuart Hygate ; Betreuer: J. M. Diederik Kruijssen." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-279482.
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Hygate, Alexander P. S. [Verfasser], and J. M. Diederik [Akademischer Betreuer] Kruijssen. "The Physics of Cloud-scale Star Formation and Feedback Across Cosmic Time / Alexander Philip Stuart Hygate ; Betreuer: J. M. Diederik Kruijssen." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1205883878/34.
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Hygate, Alexander Philip Stuart [Verfasser], and J. M. Diederik [Akademischer Betreuer] Kruijssen. "The Physics of Cloud-scale Star Formation and Feedback Across Cosmic Time / Alexander Philip Stuart Hygate ; Betreuer: J. M. Diederik Kruijssen." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1205883878/34.
Повний текст джерела
7
Nobile, Pedro Northon. "Projeto de um broker de gerenciamento adaptativo de recursos em computação em nuvem baseado em técnicas de controle realimentado." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-21062013-110725/.
Повний текст джерелаАнотація:
Computação em nuvem refere-se a um modelo de disponibilização de recursos computacionais no qual a infraestrutura de software e hardware é ofertada como um serviço, e vem se estabelecendo como um paradigma de sucesso graças a versatilidade e ao custo-efetividade envolvidos nesse modelo de negócio, possibilitando o compartilhamento de um conjunto de recursos físicos entre diferentes usuários e aplicações. Com o advento da computação em nuvem e a possibilidade de elasticidade dos recursos computacionais virtualizados, a alocação dinâmica de recursos vem ganhando destaque, e com ela as questões referentes ao estabelecimento de contratos e de de qualidade de serviço. Historicamente, as pesquisas em QoS concentram-se na solução de problemas que envolvem duas entidades: usuários e servidores. Entretanto, em ambientes de nuvem, uma terceira entidade passa a fazer parte dessa interação, o consumidor de serviços em nuvem, que usa a infraestrutura para disponibilizar algum tipo de serviço aos usuários finais e que tem recebido pouca atenção das pesquisa até o momento, principalmente no que tange ao desenvolvimento de mecanismos automáticos para a alocação dinâmica de recursos sob variação de demanda. Este trabalho consiste na proposta de uma arquitetura de gerenciamento adaptativo de recursos sob a perspectiva do modelo de negócio envolvendo três entidades, focada na eficiência do consumidor. O trabalho inspira-se em técnicas de controle realimentado para encontrar soluções adaptativas aos problemas de alocação dinâmica de recursos, resultando em uma arquitetura de broker de consumidor, um respectivo protótipo e um método de projeto de controle para sistemas computacionais dessa naturezaCLoud computing refers to a computer resource deployment model in which software and hardware infrastructure are offered as a service. Cloud computing has become a successful paradigm due to the versatility and cost-effectiveness involved in that business model, making it possible to share a cluster of physical resources between several users and applications. With the advent of cloud computing and the computer elastic resource, dynamic allocation of virtualized resources is becoming more prominent, and along with it, the issues concerning the establishment of quality of service parameters. Historically, research on QoS has focused on solutions for problems involving two entities: users and servers. However, in cloud environments, a third party becomes part of this interaction, the cloud consumer, that uses the infrastructure to provide some kind of service to endusers, and which has received fewer attention, especially regarding the development of autonomic mechanisms for dynamic resource allocation under time-varying demand. This work aims at the development of an architecture for dynamic adaptive resource allocation involving three entities, focused on consumer revenue. The research outcome is a consumer broker architecture based on feedback control, a respective architecture prototype and a computer system feedback control methodology which may be applied in this class of problems
8
DECATALDO, DAVIDE. "The Effect of Stellar and Quasar Feedback on the Interstellar Medium: Structure and Lifetime of Molecular Clouds." Doctoral thesis, Scuola Normale Superiore, 2020. http://hdl.handle.net/11384/90712.
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Berekmeri, Mihaly. "La modélisation et le contrôle des services BigData : application à la performance et la fiabilité de MapReduce." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT126/document.
Повний текст джерелаАнотація:
Le grand volume de données généré par nos téléphones mobiles, tablettes, ordinateurs, ainsi que nos montres connectées présente un défi pour le stockage et l'analyse. De nombreuses solutions ont émergées dans l'industrie pour traiter cette grande quantité de données, la plus populaire d'entre elles est MapReduce. Bien que la complexité de déploiement des systèmes informatiques soit en constante augmentation, la disponibilité permanente et la rapidité du temps de réponse sont toujours une priorité. En outre, avec l'émergence des solutions de virtualisation et du cloud, les environnements de fonctionnement sont devenus de plus en plus dynamiques. Par conséquent, assurer les contraintes de performance et de fiabilité d'un service MapReduce pose un véritable challenge. Dans cette thèse, les problématiques de garantie de la performance et de la disponibilité de services de cloud MapReduce sont abordées en utilisant une approche basée sur la théorie du contrôle. Pour commencer, plusieurs modèles dynamiques d'un service MapReduce exécutant simultanément de multiples tâches sont introduits. Par la suite, plusieurs lois de contrôle assurant les différents objectifs de qualités de service sont synthétisées. Des contrôleurs classiques par retour de sortie avec feedforward garantissant les performances de service ont d'abord été développés. Afin d'adapter nos contrôleurs au cloud, tout en minimisant le nombre de reconfigurations et les coûts, une nouvelle architecture de contrôle événementiel a été mise en œuvre. Finalement, l'architecture de contrôle optimal MR-Ctrl a été développée. C'est la première solution à fournir aux systèmes MapReduce des garanties en termes de performances et de disponibilité, tout en minimisant le coût. Les approches de modélisation et de contrôle ont été évaluées à la fois en simulation, et en expérimentation sous MRBS, qui est une suite de tests complète pour évaluer la performance et la fiabilité des systèmes MapReduce. Les tests ont été effectuées en ligne sur un cluster MapReduce de 60 nœuds exécutant une tâche de calcul intensive de type Business Intelligence. Nos expériences montrent que le contrôle ainsi conçu, peut garantir les contraintes de performance et de disponibilitéThe amount of raw data produced by everything from our mobile phones, tablets, computers to our smart watches brings novel challenges in data storage and analysis. Many solutions have arisen in the industry to treat these large quantities of raw data, the most popular being the MapReduce framework. However, while the deployment complexity of such computing systems is steadily increasing, continuous availability and fast response times are still the expected norm. Furthermore, with the advent of virtualization and cloud solutions, the environments where these systems need to run is becoming more and more dynamic. Therefore ensuring performance and dependability constraints of a MapReduce service still poses significant challenges. In this thesis we address this problematic of guaranteeing the performance and availability of MapReduce based cloud services, taking an approach based on control theory. We develop the first dynamic models of a MapReduce service running a concurrent workload. Furthermore, we develop several control laws to ensure different quality of service objectives. First, classical feedback and feedforward controllers are developed to guarantee service performance. To further adapt our controllers to the cloud, such as minimizing the number of reconfigurations and costs, a novel event-based control architecture is introduced for performance management. Finally we develop the optimal control architecture MR-Ctrl, which is the first solution to provide guarantees in terms of both performance and dependability for MapReduce systems, meanwhile keeping cost at a minimum. All the modeling and control approaches are evaluated both in simulation and experimentally using MRBS, a comprehensive benchmark suite for evaluating the performance and dependability of MapReduce systems. Validation experiments were run in a real 60 node Hadoop MapReduce cluster, running a data intensive Business Intelligence workload. Our experiments show that the proposed techniques can successfully guarantee performance and dependability constraints
10
Wu, Fei. "Ultra-Low Delay in Complex Computing and Networked Systems: Fundamental Limits and Efficient Algorithms." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu155559337777619.
Повний текст джерела
11
Gordon, Neil D. "Cluster analysis of cloud properties a method for diagnosing cloud-climate feedbacks /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3296823.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed Mar. 24, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 108-112).
12
Ringer, Mark A., Bryant J. McAvaney, Natasha Andronova, Lawrence E. Buja, Monika Esch, William J. Ingram, Bin Li, et al. "Global mean cloud feedbacks in idealized climate change experiments." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-189467.
Повний текст джерелаАнотація:
Global mean cloud feedbacks in ten atmosphere-only climate models are estimated in perturbed sea surface temperature (SST) experiments and the results compared to doubled CO2 experiments using mixed-layer ocean versions of these same models. The cloud feedbacks in any given
model are generally not consistent: the sign of the net cloud radiative feedback may vary according to the experimental design. However, both sets of experiments indicate that the variation of the total climate feedback across the models depends primarily on the variation of the net cloud feedback. Changes in different cloud types show much greater consistency between the two experiments for any individual model and amongst the set of models analyzed here. This suggests that the SST perturbation experiments may provide useful information on the processes associated with cloud changes which is not evident when analysis is
restricted to feedbacks defined in terms of the change in cloud radiative forcing.
13
Ringer, Mark A., Bryant J. McAvaney, Natasha Andronova, Lawrence E. Buja, Monika Esch, William J. Ingram, Bin Li, et al. "Global mean cloud feedbacks in idealized climate change experiments." Wiley, 2006. https://ul.qucosa.de/id/qucosa%3A13964.
Повний текст джерелаАнотація:
Global mean cloud feedbacks in ten atmosphere-only climate models are estimated in perturbed sea surface temperature (SST) experiments and the results compared to doubled CO2 experiments using mixed-layer ocean versions of these same models. The cloud feedbacks in any given
model are generally not consistent: the sign of the net cloud radiative feedback may vary according to the experimental design. However, both sets of experiments indicate that the variation of the total climate feedback across the models depends primarily on the variation of the net cloud feedback. Changes in different cloud types show much greater consistency between the two experiments for any individual model and amongst the set of models analyzed here. This suggests that the SST perturbation experiments may provide useful information on the processes associated with cloud changes which is not evident when analysis is
restricted to feedbacks defined in terms of the change in cloud radiative forcing.
14
Rey, Raposo Ramon. "The interplay between stellar feedback and galactic environment in molecular clouds." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/21022.
Повний текст джерелаАнотація:
In this thesis we address the problem of understanding the star formation process in giant molecular clouds in a galactic context. Most simulations of molecular clouds to date use an oversimplified set of initial conditions (turbulent spheres/boxes or colliding flows). Full galactic scale models are able to generate molecular clouds with complex morphologies and velocity fields but they fail to reproduce in detail the effects that occur at sub-pc scales (e.g. stellar feedback). Our goal is to build the bridge between these two scenarios, and to model the star formation process in molecular clouds produced in a galactic context. We extract our molecular clouds from full-scale galactic simulations, hence we need to increase the resolution by two orders of magnitude. We introduce the details of the program used to simulate molecular clouds in Chapter 2, and describe in detail the method we follow to increase the resolution of the galactic clouds. In Chapter 3 we compare our simulated galactic clouds with the more conventional approach of using turbulent spheres. We create turbulent spheres to match the virial state of three galactic clouds. We perform isothermal simulations and find that the velocity field inherited from the full-scale galactic simulations plays an important role in the star formation process. Clouds affected by strong galactic shear produce less stars compared with clouds that are compressed. We define (and test) a set of parameters to characterise the dynamical state of our clouds. To include stellar feedback in our simulations we need to introduce a cooling/heating algorithm. In Chapter 4 we analyse how the different velocity fields of our clouds change the temperature distribution even in the absence of feedback. To study the formation of molecules we need to model the chemistry of H2 in our clouds. We also add CO chemistry, and produce synthetic observations of our clouds. The effect of feedback from winds and supernovae in galactic clouds is studied in Chapter 5. We analyse the effect of winds in clouds with very different velocity fields. We find that the effect of winds is stronger in highly virialised, high star forming clouds, with clouds with weak galactic shear, compared to unbound shear-dominated clouds. The steady and continuous action of the winds appears to have a greater effect than the supernovae. In summary, the inherited properties from the galaxy have an impact on many relevant processes in star formation, influencing gravitational collapse, the formation of filamentary structures, the temperature field of the cloud, and have a considerable effect on the impact of feedback in the clouds.
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Quaas, Johannes. "The role of clouds in climate forcings and feedbacks." Doctoral thesis, Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-189817.
Повний текст джерелаАнотація:
Variability and change of the Earth\'s climate are of fundamental importance to humankind. In particular anthropogenic climate change has been considered widely as one of the most urgent concerns for the society (United Nations, 1992, 2002). It is therefore vital to improve the understanding of the Earth\'s climate system and its variability.
16
Tinka, Jan. "Lepší vymezení herního prostoru pro VR pomocí 3D sensorů." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2018. http://www.nusl.cz/ntk/nusl-413328.
Повний текст джерелаАнотація:
Room-scale tracking encourages users to move more freely and even walk. Even though there has been much research on making the limited physical workspace feel larger in the VR, these approaches have their limitations and require certain conditions to be met. This thesis proposes an alternative approach to the conventional play-area boundaries of high-end VR products such as the HTC Vive and Oculus Rift which are set by the user in a 2-D fashion as a means of enhance workspace utilization. A 3-D scanner is used to make a 3-D point-cloud model of the play area's surroundings. This model is then used to detect collisions and provide feedback to the user. Evaluation based on user tests showed that this approach can be useful, is well accepted by users and might be worth further research.
17
Booker, Joseph J. "Characterizing the Role of Feedback and Protostellar Properties in the Orion Molecular Clouds." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1501868933007357.
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Vogt, Linus. "The role of the upper ocean for global ocean heat uptake and climate." Electronic Thesis or Diss., Sorbonne université, 2024. https://theses.hal.science/tel-04951110.
Повний текст джерелаАнотація:
Le climat terrestre connaît actuellement des changements rapides et généralisés. Les activités humaines depuis l'ère industrielle, en particulier les émissions de CO2 dans l'atmosphère dues à la combustion de combustibles fossiles, ont intensifié l'effet de serre. Cela a entraîné une augmentation de la température moyenne de l'air à la surface du globe de 1.1°C en 2011-2020 par rapport à 1850-1900. Une autre conséquence majeure est le réchauffement des océans mondiaux, qui ont absorbé plus de 90% de l'énergie excédentaire accumulée dans le système climatique en raison de l'augmentation du forçage radiatif. L'absorption de chaleur par l'océan mondial (OHU) est un processus climatique clé qui joue un double rôle dans le changement climatique d'origine anthropique. D'une part, l'OHU constitue en soi une mesure clé du changement climatique, qui est directement associée à des impacts négatifs tels que l'élévation du niveau de la mer et l'augmentation de la fréquence des événements extrêmes dans l'océan. D'autre part, l'OHU fournit un service climatique essentiel en épargnant l'atmosphère de grandes quantités de chaleur, sans lequel le réchauffement atmosphérique serait bien plus marqué que celui que nous observons actuellement. Malgré leur importance, de nombreux processus physiques qui contrôlent l'OHU restent mal compris, même dans les modèles climatiques numériques utilisés dans les évaluations internationales du changement climatique. Dans cette thèse, nous avançons sur ce problème en nous appuyant sur des simulations climatiques issues de modèles participant au Projet d'intercomparaison des modèles couplés (CMIP). Dans une première étude, nous produisons des estimations améliorées de l'OHU global d'ici à la fin du XXIe siècle en identifiant une relation émergente dans un ensemble de modèles CMIP, qui relie l'état climatique présent de l'hémisphère sud à l'OHU futur. En combinant cette relation avec des données d'observation, nous obtenons des projections mieux contraintes qui montrent que l'OHU futur pourrait être plus important qu'estimé précédemment. Dans une deuxième étude, nous clarifions les processus à l'origine de l'efficacité d'absorption de la chaleur océanique (OHUE), qui quantifie la quantité d'OHU par degré de réchauffement de la surface terrestre. Nous réconcilions plusieurs tentatives antérieures d'explication des facteurs influençant l'OHUE, et montrons que la stratification de l'océan Austral supérieur est une propriété clé qui contrôle l'OHUE dans les modèles climatiques CMIP. Enfin, nous présentons une analyse exploratoire combinant les approches de ces deux études, et menons une analyse statistique des simulations d'un grand ensemble multi-modèle dans le but de contraindre l'OHUE. Au-delà de ces résultats concrets concernant l'OHU global, nous discutons également de certaines questions méthodologiques liées à l'interprétation des incertitudes découlant des ensembles multi-modèles de manière plus généraleThe Earth's climate is currently undergoing rapid and widespread changes. Human activities in the industrial era, in particular the emission of CO2 into the atmosphere through the burning of fossil fuels, have led to an enhanced greenhouse effect which has caused an increase in the global average surface air temperature of 1.1°C in 2011-2020 relative to 1850-1900. A further consequence is the warming of the global ocean: it has absorbed over 90% of the excess energy stored in the Earth system due to the increased radiative forcing. This global ocean heat uptake (OHU) is a critical climate process and plays a dual role for anthropogenic climate change. On the one hand, OHU is a measure of the cumulative effects of transient climate change, and scales with negative impacts such as sea level rise and the frequency of oceanic extreme events. On the other hand, OHU provides a crucial service by shielding the atmosphere from large amounts of heat that would otherwise cause much greater global warming than currently observed. Despite their importance, many of the physical processes controlling OHU are still poorly understood, including in state-of-the-art numerical climate models used for international climate change assessments. In this thesis, we address this problem using climate simulations of models participating in the Coupled Model Intercomparison Project (CMIP). In a first study, we provide improved future projections of global OHU by the end of the 21st century by identifying an emergent relationship across an ensemble of CMIP models linking the simulated baseline climate state of the Southern Hemisphere to future global OHU. By combining this relationship with observational data, we obtain constrained projections showing that future OHU is likely larger than previously thought. In a second study, we clarify the processes involved in setting the ocean heat uptake efficiency (OHUE) which quantifies the amount of OHU per degree of global surface warming. We reconcile a number of previous attempts at explaining controls on OHUE, and show that the upper ocean stratification in the Southern Ocean is a key property setting its value in CMIP climate models. Last, we present an exploratory analysis combining the approaches of these two studies, and perform a statistical analysis of simulations from a large multi-model ensemble with the goal of constraining OHUE. Beyond these concrete results concerning global OHU, we also discuss some of the methodological issues related to the interpretation of uncertainties arising from multi-model ensembles more generally
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Esposito, Federico. "Interpreting the CO SLED with starburst and AGN feedback." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14102/.
Повний текст джерелаАнотація:
Il presente lavoro di tesi si basa sullo spettro rotazionale del monossido di carbonio (CO) di 4 galassie locali, e lo interpreta sulla base della densità del mezzo molecolare responsabile dell'emissione e del tipo di sorgente radiativa che eccita tale molecola. Due
tipi di sorgente sono stati considerati: popolazioni stellari giovani (modello PDR) e AGN (modello XDR). La CO SLED è stata ricavata principalmente da osservazioni del satellite infrarosso Herschel. Per le 4 galassie studiate (IRAS F05189-2524, NGC 34, NGC 4418 e NGC 6240) sono state prodotte le mappe spazialmente risolte dell'emissione del CO delle osservazioni ALMA. Questo ci ha permesso di stabilire un'area fisica all'interno delle galassie entro cui il gas molecolare è presente ed emette radiazione. Con il codice di sintesi spettrale Cloudy (Ferland et al. 2013) abbiamo preparato due griglie di simulazioni per i modelli PDR e XDR. I risultati di queste simulazioni sono stati combinati nei modelli finali, composti di due PDRs o di una PDR ed una XDR; la CO SLED simulata è stata quindi comparata a quella osservata tramite una procedura di minimizzazione. I risultati ottenuti sono i seguenti: per due galassie (NGC 34 e NGC 6240) il modello di best-fit è quello a doppia PDR, per le altre due (IRAS F05189-2524 e NGC 4418) è il PDR + XDR. I risultati riguardanti NGC 4418 vanno considerati con cautela in quanto il codice di minimizzazione non è riuscito a trovare un buon fit della CO SLED. I 4 oggetti selezionati non sembrano in generale dominati dalla presenza delle XDRs per quanto riguarda l'eccitazione del gas molecolare, da cui si conclude che il contributo dell'AGN (osservato in tutte tranne che in NGC 4418) nel determinare la fisica del gas interstellare non è dominante. Dai modelli di best-fit sono state ricavate le masse di gas, e da queste sono stati calcolati i fattori di conversione del CO e i depletion times. Tali grandezze sono state confrontate con galassie presenti in letteratura.
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McGouldrick, Kevin Bartholomew. "Microphysics and radiative-dynamical feedback in the near infrared brightness features in the Venus clouds." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273820.
Повний текст джерела
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Kadlubiec, Jakub. "Mobilní systém pro sběr zpětné vazby zákazníků." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2013. http://www.nusl.cz/ntk/nusl-236177.
Повний текст джерелаАнотація:
Práce se zabývá popisem tvorby mobilního systému pro monitoring zákaznické spokojenosti a sběr zpětné vazby od návštěvníků v restauracích s názvem Huerate. Komplexně jsou popsané všechny fáze vývoje systému. První část práce se zabývá analýzou existujících řešení a stavem na trhu. Následně jsou na základně komunikace s majiteli restaurací sestaveny požadavky na systém. Nakonec se práce věnuje samotnému návrhu systému, jeho implementaci a nasazení v restauracích. Systém Huerate běží jako webová aplikace a je dostupný na adrese http://huerate.cz.
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Höjgård-Olsen, Erik. "Observations du cycle de l'eau atmosphérique tropicale et de ses variations avec la température de surface de la mer, à l'aide d'une constellation de satellites." Electronic Thesis or Diss., université Paris-Saclay, 2020. http://www.theses.fr/2020UPASJ007.
Повний текст джерелаАнотація:
L'atmosphère tropicale est un système complexe de processus dynamiques et thermodynamiques. A cela, s’ajoute un forçage radiatif dû aux gaz à effet de serre anthropiques et au réchauffement climatique qui en résulte. Les projections climatiques supposent souvent que le paramètre de rétroaction est constant dans le temps, de sorte que les changements de flux radiatif sont proportionnels aux changements de température de surface. En fait, les incertitudes de projections sont associées à la réponse du cycle de l’eau atmosphérique au réchauffement de la surface et motivent ainsi la nécessité de mieux comprendre les processus liant les nuages, la circulation de l’eau atmosphérique et le climat.Ce travail vise à améliorer notre compréhension de la co-variabilité des température de surface de la mer (SST), humidité relative (HR), nuages et précipitations, à différentes échelles temporelles et spatiales dans la ceinture tropicale (30°N à 30°S). Il repose sur un ensemble unique de mesures de journée (13h30) de haute résolution verticale qui regroupe le profil HR, les caractéristiques des nuages et les précipitations près de la surface fournis par le radiomètre micro onde SAPHIR, le lidar CALIOP et le radar CPR. Ces données ont une résolution horizontale de 1° par 1° et couvrent la période de 2012 à 2018. Elles sont associées aux champs de SST et de vitesse verticale de l'atmosphère des réanalyses ERA5.Cet ensemble de données a été exploré selon deux axes:(i) Le premier axe était focalisé sur la co-évolution des profils de HR, de la couverture nuageuse et de la SST, sous contrainte de circulation à grande échelle en exploitant l’échelle instantanée de variation. À notre connaissance, il s’agit d’une première analyse intégrant entièrement des observations de la réponse du cycle de l’eau atmosphérique tropicale à la SST à cette échelle. Des relations physiques sont établies pour les différents régimes de circulation de grande échelle, et leurs caractéristiques se maintiennent avec la variabilité naturelle du climat (comme El Niño-Southern Oscillation). Ainsi, le régime subsident est caractérisé par une troposphère libre sèche et une décroissance, avec l’augmentation de la SST, de la fraction de nuages opaque de phase liquide, et un refroidissement prévu par ciel clair avec SST. Le régime ascendant est caractérisé par des variations non linéaires de la fraction de nuages de phase glacée et d'HR de la troposphère avec un maximum autour d’une SST de 302 K, ce qui implique des impacts non linéaires sur les flux radiatifs.(ii) Le deuxième axe qui a été considéré portait sur l'hypothèse de facteurs de rétroaction invariants dans le temps aux échelles journalière, mensuelle, saisonnière et annuelle. Les taux de changement de l'humidité relative et des caractéristiques des nuages avec la SST définis à l'échelle globale (océans tropicaux) sont comparés aux taux de changement calculés localement, sur chaque point de la grille. Ainsi, à l'échelle globale, les changements en profil de HR et en température des nuages de glace sont peu significatifs , tandis que la couverture de nuages opaques diminue et que l'altitude des nuages de glace augmentent. Ces résultats suggèrent un renforcement du refroidissement radiatif de ciel clair avec la SST, alors que la température d'émission des nuages est invariante, ce qui est à la base de certaines hypothèses sur le fonctionnement de l’atmosphère tropicale. Ces résultats mettent en évidence des différences significatives en fonction de l'échelle de temps considérée, et qui peuvent ainsi être utilisés comme diagnostic pertinent pour l'évaluation des modèles climatiques. Une première analyse du modèle climatique de l’IPSL a été réalisée et souligne l'intérêt de tels diagnostiques basés sur des observationsThe tropical atmosphere is a complex system of dynamic and thermodynamic processes. Superimposed on these complexities is a radiative forcing due to anthropogenically emitted greenhouse gases and a resulting global warming. Climate projections often assume that the feedback parameter is constant in time, so that changes in radiative flux are proportional to changes in surface temperature. Projection uncertainties are associated with the atmospheric water cycle’s response to surface warming, and motivate the need to better understand processes linking clouds, circulation of atmospheric water and climate.This work aims to improve our understanding of the covariability of sea surface temperature (SST), relative humidity (RH), clouds and precipitation, on different temporal and spatial scales in the tropical belt (30°N-30°S). It relies on a unique synergistic dataset of high vertical resolution that measures the daytime (01:30 pm) RH profile, cloud characteristics and near-surface precipitation provided by the microwave radiometer SAPHIR, the CALIOP lidar and the CPR radar. This dataset has a 1° by 1° horizontal resolution and covers the time period 2012 to 2018. It is associated to SST and atmospheric vertical velocity fields of the ERA5 reanalysis.The synergistic dataset was explored along two scientific questions:(i) The first question concerned the instantaneous timescale and the co-evolution of RH profiles, cloud cover and SST, under large-scale circulation constraint. To our knowledge, this is the first comprehensive observational view of the tropical atmospheric water cycle’s response to SST on the instantaneous timescale. Different physical relationships are established for the different large-scale circulation regimes, and their characteristics are robust to natural variability (such as El Niño-Southern Oscillation). The descending regime is characterized by a dry free troposphere and decreasing opaque liquid cloud cover with SST, and an expected clear-sky cooling with SST. In contrast, the ascending regime is characterized by a nonlinear response in ice cloud cover and free-tropospheric RH with SST that peak around the 302 K SST, which likely induce nonlinear responses of the radiative fluxes.(ii) The second question addressed the assumption of timescale-invariant feedback factors on daily, monthly, seasonal and annual scales. Rates of changes of RH and cloud characteristics with SST defined on the global scale (tropical oceans) are compared to rates of changes computed on the grid box scale. On the global scale, negligible changes are observed in the RH profile with SST, opaque cloud cover decreases, and ice cloud altitudes rise with SST with little change in cloud temperature. These results suggest an enhanced clear-sky radiative cooling with SST, whilst cloud emission temperatures are invariant, as discussed in some assumptions on the tropical atmosphere. Overall, the results highlight significant differences according to the timescale considered for computing global scale rates of changes, which can be used as a strong diagnostic in the evaluation of climate models. Following this, a first analysis of the IPSL model was performed and shows the interest of such diagnostic based on observations
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Gehlot, Swati, and Johannes Quaas. "Convection–climate feedbacks in the ECHAM5 general circulation model: evaluation of cirrus cloud life cycles with ISCCP satellite data from aLagrangian trajectory perspective." American Meteorological Society, 2012. https://ul.qucosa.de/id/qucosa%3A13467.
Повний текст джерелаАнотація:
A process-oriented climate model evaluation is presented, applying the International Satellite Cloud Climatology Project (ISCCP) simulator to pinpoint deficiencies related to the cloud processes in the
ECHAM5general circulation model.ALagrangian trajectory analysis is performed to track the transitions of anvil cirrus originating from deep convective detrainment to cirrostratus and thin cirrus, comparing ISCCP observations and the ECHAM5 model. Trajectories of cloudy air parcels originating from deep convection are computed for both, the ISCCP observations and the model, over which the ISCCP joint histograms are used for analyzing the cirrus life cycle over 5 days. The cirrostratus and cirrus clouds originate from detrainment from deep convection decay and gradually thin out after the convective event over 3–4 days. The effect of the convection–cirrus transitions in a warmer climate is analyzed in order to understand the climate feedbacks due to deep convective cloud transitions. An idealized climate change simulation is performed using a+2-K sea surface temperature (SST) perturbation. The Lagrangian trajectory analysis over perturbed climate suggests that more and thicker cirrostratus and cirrus clouds occur in the warmer climate compared to the present-day climate. Stronger convection is noticed in the perturbed climate, which leads to an increased precipitation, especially on day -2 and -3 after the individual convective events. The shortwave and the longwave cloud forcings both increase in the warmer climate, with an increase of net cloud radiative forcing (NCRF), leading to an overall positive feedback of the increased cirrostratus and cirrus clouds from
a Lagrangian transition perspective.
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Körtgen, Bastian [Verfasser], and Robi [Akademischer Betreuer] Banerjee. "Formation and Evolution of Magnetised and Turbulent Molecular Clouds : Varying Initial Conditions and the Role of Stellar Feedback / Bastian Körtgen. Betreuer: Robi Banerjee." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://d-nb.info/1093411600/34.
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Rahner, Daniel [Verfasser], and Simon [Akademischer Betreuer] Glover. "Stellar feedback and the self-regulation of star formation in giant molecular clouds: a new semi-analytic approach / Daniel Rahner ; Betreuer: Simon Glover." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1191760472/34.
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Petkova, Maya Atanasova. "Cloudy with a chance of starlight : coupling of smoothed particle hydrodynamics and Monte Carlo radiative transfer for the study of ionising stellar feedback." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16557.
Повний текст джерелаАнотація:
Ionising radiation is present in a variety of astrophysical problems, and it is particularly important for shaping the process of star formation in molecular clouds, containing hot, high-mass stars. In order to account for the effects of ionising radiation within numerical models of star formation, we need to combine a hydrodynamics method with a radiative transfer method and obtain a radiation hydrodynamics scheme (RHD). In this thesis I achieve live radiation hydrodynamics by coupling the Smoothed Particle Hydrodynamics (SPH) code Phantom with the Monte Carlo Radiative Transfer (MCRT) code CMacIonize. Since SPH is particle-based and MCRT is grid-based, I construct an unstructured, Voronoi grid in order to establish a link between the two codes. In areas with large density gradients, a Voronoi grid based purely on the SPH particle positions achieves insufficient resolution, and therefore I propose a novel algorithm for inserting a small number of additional grid cells to improve the local resolution. Furthermore, the MCRT calculations require the knowledge of an average density for each Voronoi cell. To address this, I develop an analytic density mapping from SPH to a Voronoi grid, by deriving an expression for the integrals of a series of kernel functions over the volume of a random polyhedron. Finally, I demonstrate the validity of the live RHD through the benchmark test of D-type expansion of an H II region, where good agreement is shown with the existing literature. The RHD implementation is then used to perform a proof-of-concept simulation of a collapsing cloud, which produces high-mass stars and is subsequently partially ionised by them. The presented code is a valuable tool for future star formation studies, and it can be used for modelling a broad range of additional astronomical problems involving ionising radiation and hydrodynamics.
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Körtgen, Bastian Verfasser], and Robi [Akademischer Betreuer] [Banerjee. "Formation and Evolution of Magnetised and Turbulent Molecular Clouds : Varying Initial Conditions and the Role of Stellar Feedback / Bastian Körtgen. Betreuer: Robi Banerjee." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://nbn-resolving.de/urn:nbn:de:gbv:18-77743.
Повний текст джерела
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Schneider, Nadine, Johannes Quaas, Martin Claussen, and Christian Reick. "Satellite-based analysis of clouds and radiation properties of different vegetation types in the Brazilian Amazon region." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-189778.
Повний текст джерелаАнотація:
Land-use changes impact the energy balance of the Earth system, and feedbacks in the Earth system can dampen or amplify this perturbation. We analyze here from satellite data the response of clouds and subsequently radiation to a change of land use for the example of deforestation in the Amazon Basin. In this region, the characteristics
of different cloud types over two vegetation types (forest and crop-/grasslands) were calculated for a time period of five
years by using satellite data from the instruments MODIS and CERES. The cloud types are defined according to height, optical thickness, and fraction of cloud cover. For calculating the radiative forcing caused by deforestation, the dependency of spatial and temporal averages for the reflected shortwave and outgoing longwave radiation of the top of
the atmosphere on vegetation types were determined as well. The results show distinct differences in cloud cover and radiative forcing over crop-/grasslands and forests for the two vegetation regimes, implying a potentially significant positive cloud feedback to deforestation.
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Quaas, Johannes [Verfasser], and Martin [Akademischer Betreuer] Claußen. "The role of clouds in climate forcings and feedbacks : assessment using global modelling and satellite observations / Johannes Quaas ; Betreuer: Martin Claußen." Leipzig : Universitätsbibliothek Leipzig, 2015. http://d-nb.info/1240241259/34.
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Ramachandran, Varsha [Verfasser], and Wolf-Rainer [Akademischer Betreuer] Hamann. "Massive star evolution, star formation, and feedback at low metallicity : quantitative spectroscopy of OB stars in the Magellanic Clouds / Varsha Ramachandran ; Betreuer: Wolf-Rainer Hamann." Potsdam : Universität Potsdam, 2019. http://d-nb.info/1218405058/34.
Повний текст джерела
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Schneider, Nadine, Johannes Quaas, Martin Claussen, and Christian Reick. "Satellite-based analysis of clouds and radiation properties of different vegetation types in the Brazilian Amazon region." American Institute of Physics, 2013. https://ul.qucosa.de/id/qucosa%3A12942.
Повний текст джерелаАнотація:
Land-use changes impact the energy balance of the Earth system, and feedbacks in the Earth system can dampen or amplify this perturbation. We analyze here from satellite data the response of clouds and subsequently radiation to a change of land use for the example of deforestation in the Amazon Basin. In this region, the characteristics
of different cloud types over two vegetation types (forest and crop-/grasslands) were calculated for a time period of five
years by using satellite data from the instruments MODIS and CERES. The cloud types are defined according to height, optical thickness, and fraction of cloud cover. For calculating the radiative forcing caused by deforestation, the dependency of spatial and temporal averages for the reflected shortwave and outgoing longwave radiation of the top of
the atmosphere on vegetation types were determined as well. The results show distinct differences in cloud cover and radiative forcing over crop-/grasslands and forests for the two vegetation regimes, implying a potentially significant positive cloud feedback to deforestation.
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Albright, Anna Lea. "The trade-wind boundary layer and climate sensitivity." Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS207.
Повний текст джерелаАнотація:
La réponse des nuages des régimes d'alizés au réchauffement climatique reste incertaine. Elle soulève notamment la possibilité d'une sensibilité climatique élevée due à une diminution de la fraction nuageuse sous l'effet de l'interaction entre le mélange convectif, la turbulence, le rayonnement et l'environnement à grande échelle. La campagne EUREC4A (Elucidation du rôle du couplage nuage-circulation dans le climat) a apporté de nouvelles observations qui permettent de mieux comprendre la physique des régimes d'alizés, et d'apporter pour la première fois une contrainte sur la rétroaction des cumulus d'alizés basée sur les processus. Je montre d'abord comment les observations EUREC4A permettent d'approfondir la compréhension de la structure verticale caractéristique de la couche limite des alizés et des processus qui produisent cette structure. Elles amènent à revisiter certains aspects des modèles conceptuels et suggèrent un rôle plus actif des nuages dans le maintien de cette structure. Cette compréhension physique est ensuite appliquée à l'évaluation des rétroactions des cumulus d'alizés, montrant que les observations rendent peu plausibles les fortes rétroactions des cumulus d'alizés dans le réchauffement climatiqueThe response of trade-wind clouds to warming remains uncertain, raising the specter of a large climate sensitivity. Decreases in cloud fraction are thought to relate to interplay among convective mixing, turbulence, radiation, and the large-scale environment. The EUREC4A (Elucidating the role of cloud-circulation coupling in climate) field campaign made extensive measurements that allow for deeper physical understanding and the first process-based constraint on the trade cumulus feedback.I first use EUREC4A observations to improve understanding of the characteristic vertical structure of the trade-wind boundary layer and the processes that produce this structure. This improved physical understanding is then applied to the evaluation of trade cumulus feedbacks. Ideas developed support new conceptual models of the structure of the trade-wind boundary layer and a more active role of clouds in maintaining this structure, and show little evidence for a strong trade cumulus feedback to warming
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Atlidakis, Evangelos. "Structure and Feedback in Cloud Service API Fuzzing." Thesis, 2021. https://doi.org/10.7916/d8-2bry-am81.
Повний текст джерелаАнотація:
Over the last decade, we have witnessed an explosion in cloud services for hosting software applications (Software-as-a-Service), for building distributed services (Platform- as-a-Service), and for providing general computing infrastructure (Infrastructure-as-a- Service). Today, most cloud services are programmatically accessed through Application Programming Interfaces (APIs) that follow the REpresentational State Trans- fer (REST) software architectural style and cloud service developers use interface-description languages to describe and document their services. My thesis is that we can leverage the structured usage of cloud services through REST APIs and feedback obtained during interaction with such services in order to build systems that test cloud services in an automatic, efficient, and learning-based way through their APIs.
In this dissertation, I introduce stateful REST API fuzzing and describe its implementation in RESTler: the first stateful REST API fuzzing system. Stateful means that RESTler attempts to explore latent service states that are reachable only with sequences of multiple interdependent API requests. I then describe how stateful REST API fuzzing can be extended with active property checkers that test for violations of desirable REST API security properties. Finally, I introduce Pythia, a new fuzzing system that augments stateful REST API fuzzing with coverage-guided feedback and learning-based mutations.
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Nolan, Christopher. "Understanding Protostellar Jet Feedback on Disc and Cloud Scales." Phd thesis, 2019. http://hdl.handle.net/1885/195683.
Повний текст джерелаАнотація:
Protostellar jets are a vital part of the star formation process. They are responsible for the removal of excess angular momentum critical to the growth of protostars, while feeding that angular momentum back into molecular clouds to regulate the formation of stellar cores and gravitational collapse. To better understand the origin and impact of protostellar jets, this thesis investigates the launching of protostellar disc winds and the driving of non-isothermal turbulence in the interstellar medium.
In the first part of this thesis, we explore how the structure of protostellar discs relates to the properties of the wind-launching region, which directly effects the large-scale properties of the jet. In order to study the launching of disc winds, we first design a 1+1.5D magnetohydrodynamic (MHD) model of the launching region in the [r,z] plane. We take into account the three diffusion mechanisms of non-ideal MHD (Ohm, Hall, and ambipolar) by calculating their contributions at the disc midplane and using a simplified, vertically-scaled approach for higher z. We observe that most of the mass launched by the wind is concentrated within a radially localized region a fraction of an astronomical unit (au) in width, in agreement with current observations. We find that the footprint radius and the wind efficiency, measured by the ratio of the wind mass-loss rate to the rate of material accreted onto the star, are a strong function of the model parameters, namely the mass accretion rate, magnetic field strength, and surface density profile of the disc. Understanding the structure of the wind-launching region has important
We subsequently improve the 1+1.5D models by removing the vertical scaling approximation to the non-ideal MHD terms and calculate the magnetic diffusivities self-consistently at all heights above the disc midplane. This results in increased field-matter coupling surrounding the midplane, increasing the poloidal magnetic field bending and compressing the disc via enhanced magnetic pressure gradients. It also shifts the wind-launching region to smaller radii, decreases the overall wind mass-loss rate by an order of magnitude, and generates a radially symmetric wind mass-loss profile.
In the second part of this thesis, we investigate the properties of driven, turbulent, adiabatic gas. The density variance--Mach number relation of the turbulent interstellar medium is a key ingredient for analytical models of star formation. We examine the robustness of the standard, isothermal form of this relation in the non-isothermal regime, specifically testing ideal gases with diatomic molecular and monatomic adiabatic indices. Stirring the gas with purely solenoidal forcing at low wavenumbers, we find that as the gas heats in adiabatic compressions, it evolves along a curve in the density variance-Mach number plane, but deviates significantly from the standard isothermal relation. We provide new empirical and theoretical relations that take the adiabatic index into account and provide good fits for a range of Mach numbers.
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Jhan, Fu-Jie, and 詹富傑. "Cloud Based Evolution Algorithm with Feedback Control for Emergency Logistic." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/a223zd.
Повний текст джерелаАнотація:
碩士國立虎尾科技大學
資訊工程研究所
100
This paper develops a parallel and distributed evolutionary algorithm based on the cloud computing environment and feedback control algorithm to help planners solve the emergency logistic problems more efficiently and efficiently. The cloud environment is emulated and used as various virtual machines with different types of evolution procedures. To yield both exploration and exploitation, two crossover processes are deployed on different virtual machines. In the process of crossover, local optimal solutions can be competed and evaluated to form new populations so that the search space can be expanded and the advantaged crossover procedures can be further adopted. The proposed feedback control algorithm based on the evaluation of evolution algorithm can interact and emphasize the process with better performance. According to proposed feedback algorithm, virtual machines with different on demand formatted crossover algorithm can be dynamically established and adopted. Taking the advantage of cloud computing environment and the proposed feedback control algorithm of evolution algorithm, planners can take less effort on deploying both computation power and storage space. Also, it can further applied in various complicated applications more practically.
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Lin, Chia Fan, and 林家範. "Improving Accessing Efficiency of Cloud Storage by De-duplication and Feedback Scheme." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/12574844071861487555.
Повний текст джерелаАнотація:
碩士淡江大學
電機工程學系碩士班
99
In a cloud storage environment, file distribution and storage is processed by storage devices providers or physical storage devices rented from the third-party companies. Through centralized management and virtualization, files are integrated into available resources for users to access. Common file storage protocols include ISCSI, Fibre Channel, CIFS and so on, which transmit or store files based on blocks or types. Moreover, because of the wide range and extensive domains of the cloud network, it is very possible that files saved by different users on the same storage device are extremely similar. Also, due to the increasing number of files, the manager cannot guarantee the optimal status of each storage node. The great number of files not only leads to the waste of hardware resources, but also worsens the control complexity of data center, which further degrades the performance of the cloud storage system. For this reason, to decrease the workload caused by duplicated files, this paper proposes a new data management structure: Index Name Server (INS), which integrates data de-duplication with nodes optimization to enhance the performance of the cloud storage system. INS can manage and optimize the nodes according to the client-side transmission conditions. By INS, each node can be controlled to work in the best status and matched to suitable clients as possible. In such a manner, we can efficiently increase the performance of the cloud storage network and distribute the files reasonably to reduce the load of each node.
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Huang, Hao-Ching, and 黃浩慶. "The construction of a feedback digital content annotation system in the cloud computing environment." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/30777155022658996632.
Повний текст джерелаАнотація:
碩士中原大學
資訊管理研究所
99
Abstract The main drawback of traditional e-learning is user only could receive the knowledge one-way but not get feedback immediately when he has any questions. That normally comes out with bad learning performance and let user abandons this learning method. Basing on the improvement of technology, the new interactive feedback digital content annotation system was developed to solve browser constraint problem and integrate teaching, learning and interactive features together in widget. User could discuss issue and share information with each other, have a better learning effect and increase his learning willingness. However, the system may not afford the increasing amount of user, which could easily make system slow down even out of service. So the main purpose of this study is constructing an e-learning cloud computing circumstance which system resources can be adjusted with the elasticity of demand, also add nodes to expand the integration resource without modifying the application when system service amount extended. This study uses open source cloud computing suite OpenNebula to construct a private cloud environment which feedback digital content annotation system was installed. The system would have system performance test to realize the benefit of feedback digital content annotation system in the cloud computing environment. The study shows that feedback digital content annotation system which built on the cloud computing environment could have more resource configuration and expand flexibility, also could improve system performance, and solve the issue of traditional e-learning system for multimedia data processing overload that lead to system instability, increase system availability, improve overall system efficiency.
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Jhou, Yi-Chen, and 周奕辰. "Modular Feedback Assistance Hybrid Evolution Algorithm Based on Cloud Environment for Job Shop Scheduling Problem Optimization." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/x8s9jy.
Повний текст джерелаАнотація:
碩士國立虎尾科技大學
資訊工程研究所
103
This thesis develops Modular Feedback Assistance Hybrid Evolution Algorithm Based on Cloud Environment to find the optimal solution of NP-complete problems such as job shop scheduling problems. In this research, the different steps and types of the evolution algorithm can be established via individual thread procedures based on various virtual machines in cloud. After the evolution steps, methods, or procedures of the genetic algorithm, the fitness evaluation result and survival ratio of different crossover methods in the current generation can be used for the proposed feedback assistance method. The feedback assistance method can be added into the evolution procedure and dynamically emphasize the corresponding methods or procedures with better performance in optimal solution searching. All the steps or methods in genetic algorithm are created independently (or modular). Furthermore, via using the feedback assistance, the convergence time of the optimal solution can be enhanced.
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Lee, Kuan-wei, and 李寬瑋. "Modular Cloud Hybrid Evolution Algorithm Based on Feedback Assistance for Optimal Data Solution in Traveling Salesman Problem." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/35h9tm.
Повний текст джерелаАнотація:
碩士國立虎尾科技大學
資訊工程研究所
102
This paper develops a modular cloud hybrid evolution algorithm based on feedback assistance for optimal data solution in traveling salesman problem. Different steps and types of the evolution algorithm can be established via individual thread procedures and various virtual machines in cloud. According to the proposed XML format, system users can upload only the coding of chromosomes without the evolution algorithm implementation. The proposed feedback assistance is based on the fitness evaluation result and survival ratio of different crossover methods. The Reduce the cost for establishing the evolution algorithm according to the proposed system can. The feedback assistance can interact with the different crossover methods and emphasize the method that can enhance more survival individuals for the next evolution generation. Furthermore, via using the feedback assistance, the convergence time of the optimal solution can be enhanced.
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Fong, Chin-Tzu, and 馮欽賜. "The effect and feedback of cirrus cloud on the climate system by a three dimensional climate model study." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/38677053275187528349.
Повний текст джерела
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Ching, Yun-ting, and 卿韻亭. "On the Research of Windows API-based Experimental State Feedback Mechanism ─A Case Study on the Cloud Security Experimental Platform." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/8xx2qt.
Повний текст джерелаАнотація:
碩士國立中央大學
資訊管理學系
102
With the rapid development of Internet, many personalized services also rise and bring many business opportunities. In addition to the application of personalized service recommendation in the field of e-commerce, some application of personal e-learning also exists in the field of providing personalized services. While providing these personalized services, the most important thing is "To get user's action behavior when they using the service." There are many academic literatures and mechanisms about how do we access and identify user's action behavior, but this information is still not enough to show the details of user's operating behavior. In order to identify user's action behavior more accurately, our study presents the Experimental Status Feedback Mechanism (ESFM). ESFM could instantly capture user's action on Windows OS. Our study use Cloud Security Experimental Platform (CSEP) as an example, CSEP is an e-learning platform and provided with interactive teaching. Therefore, through ESFM could capture user's action when they do some operations on the virtual machine. When ESFM capture this information, it will send this information to CSEP server, allowing users to follow steps and finishing their experiments. The ESFM we proposed has been proven that it can aptly capture the user's actions and recognize the window and widgets information. ESFM not only has lower impact on system performance, but improve the Sikuli mechanism used in CSEP experiments. Therefore, ESFM could capture the user's operation without affecting them on the virtual machine and used for future design of CSEP experiments.
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Yin, Jun. "Land-atmosphere Interaction: from Atmospheric Boundary Layer to Soil Moisture Dynamics." Diss., 2015. http://hdl.handle.net/10161/10474.
Повний текст джерелаАнотація:
Accurate modeling of land-atmosphere interaction would help us understand the persistent weather conditions and further contribute to the skill of seasonal climate prediction. In this study, seasonal variations in radiation and precipitation forcing are included in a stochastic soil water balance model to explore the seasonal evolution of soil moisture probabilistic structure. The theoretical results show soil moisture tends to exhibit bimodal behavior only in summer when there are strong positive feedback from soil moisture to subsequent rainfall. Besides the statistical analysis of soil moisture – rainfall feedback, simplified mixed-layer models, coupled with soil-plant-atmosphere continuum, are also used to study heat flux partitioning, cloud initiation, and strength of moist convection. Approximate analytical solutions to the mixed-layer model are derived by applying Penman-Monteith approach, which help explain the roles of equilibrium evaporation and vapor pressure deficit in controlling the diurnal evolution of boundary layer. Results from mixed-layer model also define four regimes for possible convection in terms of cloud/no-cloud formation and low/high convection intensity. Finally, cloud-topped mixed-layer model is developed to simulate the boundary-layer dynamics after the cloud formation, when the evaporative and radiative cooling other than surface heat flux may significantly contribute to the growth of the boundary layer.
Dissertation
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"Microphysics and radiative-dynamical feedback in the near infrared brightness features in the Venus clouds." UNIVERSITY OF COLORADO AT BOULDER, 2008. http://pqdtopen.proquest.com/#viewpdf?dispub=3273820.
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Quaas, Johannes. "The role of clouds in climate forcings and feedbacks: assessment using global modelling and satellite observations." Doctoral thesis, 2010. https://ul.qucosa.de/id/qucosa%3A13997.
Повний текст джерелаАнотація:
Variability and change of the Earth\''s climate are of fundamental importance to humankind. In particular anthropogenic climate change has been considered widely as one of the most urgent concerns for the society (United Nations, 1992, 2002). It is therefore vital to improve the understanding of the Earth\''s climate system and its variability.