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Статті в журналах з теми "Stream conservation Mathematical models"
1
ALI MUNZER, SULEIMAN, D. S. BEGLYAROV, and R. R. SHAKIROV. "FEATURES AND ANALYSIS OF STUDIES OF FISH PROTECTION COMPLEX FOR WATER RECEIVERS OF LARGE HIGH-PRESSURE HYDROELECTRIC POWER PLANTS." Prirodoobustrojstvo, no. 2 (2022): 86–93. http://dx.doi.org/10.26897/1997-6011-2022-2-86-93.
Повний текст джерелаАнотація:
Development of effective fish protection measures at water intakes is one of the main directions of fish resources conservation and reproduction in inland water bodies of the country. Its complexity is associated with the involvement of many related disciplines: ichthyology, physiology, hydrobiology, ecology, hydraulics, hydrology, etc. In the process of solving the problem of standardization of information to be used for creating mathematical models for forecasting potential impact of water intakes with fish protection on aquatic ecosystem. The article gives a review of the research on the technology of aquatic bioresources (ABR) conservation, conducted by JSC «Institute Hydroproject» (Moscow) together with LLC «Hydrotechnika» (Sochi), the basic provisions of modeling methodology are considered; the results of mathematical modeling of currents in the upstream in the area of hydraulic units, spillways and rockfi ll dam at Boguchanskaya HPP; results of experimental studies of stream generators and biohydraulic modeling. The assessment of the conducted research is given.
2
Bondarenko, A., M. Savin, O. Supotnitskaya, and L. Yantseva. "ON COMBINED BURNING RATE OF LIQUID SODIUM STREAM AND POOL." PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. SERIES: NUCLEAR AND REACTOR CONSTANTS 2019, no. 1 (March 26, 2019): 224–29. http://dx.doi.org/10.55176/2414-1038-2019-1-224-229.
Повний текст джерелаАнотація:
Sodium fires with heat and fume release often happen at coolant circuit rupture of sodium fast reactor. At nuclear power plant with the sodium fast reactor the more probable scenario of sodium fire is considered burning of falling from damaged pipeline liquid sodium stream and the pool formed under it. The simple models for sodium fire which contains minimum of phenomenological parameters and gives the opportunity to get the upper limits of heat generation and amount of aerosol generated at sodium fire are more preferable. The physical and mathematical model for estimation a combined burning rate of the freely falling liquid sodium stream and the pool formed under it is proposed. The model is based on the laws of energy and mass conservation, the empiric correlations for burning rate of stream and pool sodium and assumption that pool depth cannot be less than equilibrium. The equilibrium pool depth depends on surface tension of liquid sodium. The probable heat transfer techniques for steam-phase and heterogeneous burning of metal are discussed. The experimental data of the Monju's sodium fire imitation are used for verification of the model presented. Good agreement between experimental and calculated data is observed.
3
Timakova, R. T. "Adaptive modeling of experimental conditions in the processing of food products (chilled fish) by the flow of accelerated electrons." Proceedings of the Voronezh State University of Engineering Technologies 83, no. 1 (June 3, 2021): 17–22. http://dx.doi.org/10.20914/2310-1202-2021-1-17-22.
Повний текст джерелаАнотація:
The use of mathematical modeling in various branches of the food industry as an effective tool for the policy of resource conservation of food systems is an innovative solution in the field of improving the efficiency of existing food production technologies based on established patterns in the production process. The issues of operational quality control in the process of processing food products with a stream of accelerated electrons in the absence of radiation doses regulated by standards, except for certain types of spices, to ensure the safety and quality of food products, in particular chilled fish, require a constructive approach with the general predictability of technological parameters in specialized radiation centers – operators of the irradiator. It was found that the dose absorbed by the samples of common carp scales with a high degree of correlation of 0.94 depends on the actual radiation dose and increases to 7.51±0.04 kGy when irradiated with a dose of 12 kGy or 25.9 times compared to samples treated with a stream of accelerated electrons with a radiation dose of 1 kGy. It is revealed that the operational quality is determined by the reproducibility of the results under the established conditions of the production processing process. As a result of experimental testing, mathematical models of various types were developed to predict the absorbed dose from experimental conditions on the example of samples of chilled carp scales: polynomial, 3D-graph and arccos. The practical significance is determined by the possibility of designing experimental conditions for processing chilled fish with a stream of accelerated electrons without performing trial processing of small batches of food products in radiation centers and using emitters as a model for technological runs.
4
Udalov, A. A., M. Yu Uleysky, and M. V. Budyansky. "Analysis of Stationary Points and Bifurcations of a Dynamically Consistent Model of a Two-dimensional Meandering Jet." Nelineinaya Dinamika 18, no. 4 (2022): 0. http://dx.doi.org/10.20537/nd220802.
Повний текст джерелаАнотація:
A dynamically consistent model of a meandering jet stream with two Rossby waves obtained using the law of conservation of potential vorticity is investigated. Stationary points are found in the phase space of advection equations and the type of their stability is determined analytically. All topologically different flow regimes and their bifurcations are found for the stationary model (taking into account only the first Rossby wave). The results can be used in the study of Lagrangian transport, mixing, and chaotic advection in problems of cross-frontal transport in geophysical flows with meandering jets.
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Dobrynin, Ye, and V. Davydov. "SIMULATION MODEL OF THE INFORMATION TECHNOLOGY FOR THE TECHNICAL DIAGNOSIS OF THE IMPULSE HEAT MACHINE." Odes’kyi Politechnichnyi Universytet Pratsi 2, no. 61 (2020): 95–103. http://dx.doi.org/10.15276/opu.2.61.2020.11.
Повний текст джерелаАнотація:
A simulation model of the information technology for the technical diagnosis of the impulse heat machine has been developed and studied. The model incorporates such mathematical models as barrel energy; ballistic wave parameters; pressure of powder gases blasting from the barrel face behind the shell and the shot blast and determination of its attenuation rate. The information model enables to obtain parameters of the ballistic wave that accompanies an shot. A simplified mathematical model allows of determining the oblique shock inclination angle to the stream speed depending on Mach number which is represented by the two-dimensional flow wedge. The model of powder gas pressure blasting from the barrel face behind the shell is based on the energy conservation law for the compresses powder gases and makes it possible to avoid solution of the complicated modified Lagrange problem. While the shot blast propagates, at the initial stage it is possible that this blast reaches the record point earlier than the ballistic wave. Such phenomenon can be avoided by selecting a proper angle. The adopted mathematical model determines the shot blast propagation law and allows of evaluating the shot blast speed attenuation. The barrel energy model was based on the solution of the inverse problem of pyrostatics by determining a composition of the combustion gas of the shot. The applied approach provided for use of the model that describes combustion of the fuel and oxidizer mixture. The peculiarity is a necessity to know composition of all components of the arbitrary mixture. The limitation is a necessity that all components are gaseous. The considered case needs to develop a combustion model of a single-component solid substance (nitrocellulose powder) that provides for a possibility to vary the composition of its active part because of its degradation with time.
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Lutz, Stefanie R., Ype van der Velde, Omniea F. Elsayed, Gwenaël Imfeld, Marie Lefrancq, Sylvain Payraudeau, and Boris M. van Breukelen. "Pesticide fate on catchment scale: conceptual modelling of stream CSIA data." Hydrology and Earth System Sciences 21, no. 10 (October 18, 2017): 5243–61. http://dx.doi.org/10.5194/hess-21-5243-2017.
Повний текст джерелаАнотація:
Abstract. Compound-specific stable isotope analysis (CSIA) has proven beneficial in the characterization of contaminant degradation in groundwater, but it has never been used to assess pesticide transformation on catchment scale. This study presents concentration and carbon CSIA data of the herbicides S-metolachlor and acetochlor from three locations (plot, drain, and catchment outlets) in a 47 ha agricultural catchment (Bas-Rhin, France). Herbicide concentrations at the catchment outlet were highest (62 µg L−1) in response to an intense rainfall event following herbicide application. Increasing δ13C values of S-metolachlor and acetochlor by more than 2 ‰ during the study period indicated herbicide degradation. To assist the interpretation of these data, discharge, concentrations, and δ13C values of S-metolachlor were modelled with a conceptual mathematical model using the transport formulation by travel-time distributions. Testing of different model setups supported the assumption that degradation half-lives (DT50) increase with increasing soil depth, which can be straightforwardly implemented in conceptual models using travel-time distributions. Moreover, model calibration yielded an estimate of a field-integrated isotopic enrichment factor as opposed to laboratory-based assessments of enrichment factors in closed systems. Thirdly, the Rayleigh equation commonly applied in groundwater studies was tested by our model for its potential to quantify degradation on catchment scale. It provided conservative estimates on the extent of degradation as occurred in stream samples. However, largely exceeding the simulated degradation within the entire catchment, these estimates were not representative of overall degradation on catchment scale. The conceptual modelling approach thus enabled us to upscale sample-based CSIA information on degradation to the catchment scale. Overall, this study demonstrates the benefit of combining monitoring and conceptual modelling of concentration and CSIA data and advocates the use of travel-time distributions for assessing pesticide fate and transport on catchment scale.
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Marcinkowski, Paweł, and Dorota Mirosław-Świątek. "Modelling of climate change impact on flow conditions in the lowland anastomosing river." PeerJ 8 (June 23, 2020): e9275. http://dx.doi.org/10.7717/peerj.9275.
Повний текст джерелаАнотація:
The progressive degradation of freshwater ecosystems worldwide requires action to be taken for their conservation. Nowadays, protection strategies need to step beyond the traditional approach of managing protected areas as they have to deal with the protection or recovery of natural flow regimes disrupted by the effects of future climate conditions. Climate change affects the hydrosphere at catchment scale altering hydrological processes which in turn impact hydrodynamics at the river reach scale. Therefore, conservation strategies should consider mathematical models, which allow for an improved understanding of ecosystem functions and their interactions across different spatial and temporal scales. This study focuses on an anastomosing river system in north-eastern Poland, where in recent decades a significant loss of the anabranches has been observed. The objective was to assess the impact of projected climate change on average flow conditions in the anastomosing section of the Narew River. The Soil and Water Assessment Tool (SWAT software) for the Narew catchment was coupled with the HEC-RAS one-dimensional unsteady flow model. The study looked into projected changes for two future time horizons 2021–2050 and 2071–2100 under the Representative Concentration Pathway 4.5 using an ensemble of nine EURO-CORDEX model scenarios. Results show that low flow conditions in the anastomosing section of the Narew National Park will remain relatively stable in 2021–2050 compared to current conditions and will slightly increase in 2071–2100. Duration of low flows, although projected to decrease on an annual basis, will increase for August–October, when the loss on anastomoses was found to be the most intense. Hydraulic modeling indicated extremely low flow velocities in the anastomosing arm (<0.1 m/s) nowadays and under future projections which is preferable for in-stream vegetation development and their gradual sedimentation and closure.
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An, Chenge, Andrew J. Moodie, Hongbo Ma, Xudong Fu, Yuanfeng Zhang, Kensuke Naito, and Gary Parker. "Morphodynamic model of the lower Yellow River: flux or entrainment form for sediment mass conservation?" Earth Surface Dynamics 6, no. 4 (November 6, 2018): 989–1010. http://dx.doi.org/10.5194/esurf-6-989-2018.
Повний текст джерелаАнотація:
Abstract. Sediment mass conservation is a key factor that constrains river morphodynamic processes. In most models of river morphodynamics, sediment mass conservation is described by the Exner equation, which may take various forms depending on the problem in question. One of the most widely used forms of the Exner equation is the flux-based formulation, in which the conservation of bed material is related to the stream-wise gradient of the sediment transport rate. An alternative form of the Exner equation, however, is the entrainment-based formulation, in which the conservation of bed material is related to the difference between the entrainment rate of bed sediment into suspension and the deposition rate of suspended sediment onto the bed. Here we represent the flux form in terms of the local capacity sediment transport rate and the entrainment form in terms of the local capacity entrainment rate. In the flux form, sediment transport is a function of local hydraulic conditions. However, the entrainment form does not require this constraint: only the rate of entrainment into suspension is in local equilibrium with hydraulic conditions, and the sediment transport rate itself may lag in space and time behind the changing flow conditions. In modeling the fine-grained lower Yellow River, it is usual to treat sediment conservation in terms of an entrainment (nonequilibrium) form rather than a flux (equilibrium) form, in consideration of the condition that fine-grained sediment may be entrained at one place but deposited only at some distant location downstream. However, the differences in prediction between the two formulations have not been comprehensively studied to date. Here we study this problem by comparing the results predicted by both the flux form and the entrainment form of the Exner equation under conditions simplified from the lower Yellow River (i.e., a significant reduction of sediment supply after the closure of the Xiaolangdi Dam). We use a one-dimensional morphodynamic model and sediment transport equations specifically adapted for the lower Yellow River. We find that in a treatment of a 200 km reach using a single characteristic bed sediment size, there is little difference between the two forms since the corresponding adaptation length is relatively small. However, a consideration of sediment mixtures shows that the two forms give very different patterns of grain sorting: clear kinematic waves occur in the flux form but are diffused out in the entrainment form. Both numerical simulation and mathematical analysis show that the morphodynamic processes predicted by the entrainment form are sensitive to sediment fall velocity. We suggest that the entrainment form of the Exner equation might be required when the sorting process of fine-grained sediment is studied, especially when considering relatively short timescales.
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Pereira, Marcelo Divino Ribeiro, and João Batista Pereira Cabral. "Perda de Solo no Alto Curso das Bacias Hidrográficas dos Ribeirões Taquaruçu Grande e Taquaruçuzinho, Palmas (TO)." Revista Brasileira de Geografia Física 14, no. 1 (April 20, 2021): 332. http://dx.doi.org/10.26848/rbgf.v14.1.p332-339.
Повний текст джерелаАнотація:
A aplicação de modelos matemáticos na análise da perda de solo em bacias hidrográficas ganhou atenção, nos anos de 1960 e 1970, a partir da análise integrada da paisagem. Nesse contexto, a Equação Universal de Perda de Solo (EUPS) se destaca como um dos modelos mais utilizados mundialmente no conhecimento dos processos erosivos e no planejamento ambiental. Diante disso, este estudo tem por objetivo estimar as perdas de solos nas bacias hidrográficas dos córregos Macacão e Mutum, localizadas no município de Palmas (TO). Os resultados demonstram que as áreas estudadas sofreram com um alto poder de erosividade (R) ao longo dos anos 1995 a 2019, com valores entre 12,188 a 12,319 t/ha MJ-1 mm-1. Quanto ao solo, o Neossolo Litólico Distrófico (RLD) apresenta o maior valor de erodibilidade (K), 0,049 t/ha MJ-1 mm-1.No que tange ao fator topográfico (LS), cerca de 80% das áreas das bacias mostram valores de LS considerados baixos, situados entre 0,029 a 1,86, e 1,86 a 4,30. Já para o fator relacionado ao uso e manejo do solo e às práticas conservacionistas (CP), as áreas mais suscetíveis ao processo erosional diz respeito às classes de pastagem e queimadas. Desta forma, observa-se que as classes de erosão hídrica nas bacias são consideradas moderada, grave e muito grave pelo estudo da Food and Agriculture Organization (FAO) de 1984, ainda que represente somente 19% da área da bacia do Macacão e 24% da bacia do Córrego Mutum. Loss of soil in the high course of hydrographic basins of ribeirões Taquaruçu Grande and Taquaruçuzinho, Palmas (TO) A B S T R A C TThe application of mathematical models in the analysis of soil loss in watersheds gained attention in the 1960s and 1970s from the integrated analysis of the landscape. In this context, the Universal Soil Loss Equation (EUPS) stood out as one of the most used models worldwide in the knowledge of erosion processes and in environmental planning. Therefore, this study aims to estimate soil losses in the hydrographic basins of the Macacão and Mutum streams, located in the municipality of Palmas (TO). The results demonstrate that the studied areas suffered from a high power of erosivity (R) over the years 1995 to 2019, with values between 12.188 to 12.319 t/ha MJ-1 mm-1. As for the soil, the Neosol Litolic Dystrophic (RLD) has the highest erodibility value (K), 0.049 t/ha MJ-1 mm-1. Regarding the topographic factor (LS), about 80% of the basin areas show LS values considered low, situated between 0.029 to 1.86, and 1.86 to 4.30. As for the factor related to the use and management of soil and conservation practices (CP), the areas most susceptible to the erosion process concern the grazing and burning classes. Thus, it is observed that the classes of water erosion in the basins are considered moderate, severe and very severe by the Food and Agriculture Organization (FAO) study of 1984, although it represents only 19% of the area of the Macacão basin and 24% of the Mutum Stream basin.Keywords: Water erosion. Hydrographic basin. USLE.
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Vasarevičius, Saulius, Asta Mineikaitė, and Petras Vaitiekūnas. "INVESTIGATION INTO HEAVY METALS IN STORM WASTEWATER FROM VILNIUS ŽIRMŪNAI DISTRICT AND POLLUTANTITS SPREAD MODEL IN NERIS RIVER." JOURNAL OF ENVIRONMENTAL ENGINEERING AND LANDSCAPE MANAGEMENT 18, no. 3 (September 30, 2010): 242–49. http://dx.doi.org/10.3846/jeelm.2010.28.
Повний текст джерелаАнотація:
The paper discusses investigation into uncleaned storm wastewater pollution with heavy metals in Vilnius Žirmūnai district. The goal is to determine the dependency of storm wastewater pollution with heavy metals on transport intensity. After determining this dependency, sweeps from street points is experimentally studied with the most intensive transport flows. As the street sweeps together with storm wastewater are both outflow from streets and through outflow pipes directly to the Neris, heavy metals in the outflow pipe sludge are also studied for each pool. The following heavy metals have been experimentally studied: Pb, Mn, Cr, Zn, Cu, Ni. The flame atomic absorption spectrometry method was used. The process of analysis is explained in short and its results are provided. A mathematical model by Phoenics 3.5 version program showing the distribution of heavy metals in the Neris river stream is made on the basis of the results received. Santrauka Nagrinejama nevalomu lietaus nuoteku tarša sunkiaisiais metalais Vilniaus Žirmūnu rajone. Siekiant nustatyti ryši tarp lietaus nuoteku užterštumo sunkiaisiais metalais nuo transporto eksperimentiškai tiriamos sašlavos nuo gatviu, kuriuos su lietumi išplaunamos i upe. Taip pat tiriami sunkieji metalai iš lietaus ištekamuju vamzdžiu i Neri. Eksperimentiškai nagrinejami šie sunkieji metalai: Pb, Mn, Cr, Zn, Cu, Ni. Tam panaudotas liepsnos absorbcijos spektrometrinis metodas. Trumpai aptariamas analizes procesas ir pateikiami tyrimu rezultatai. Remiantis gautais rezultatais sudaromas matematinis teršalu sklaidos modelis Neries upes tekmeje taikant Phoenics 3.5 programa. Резюме Исследуется загрязнение неочищаемых дождевых стоков тяжелыми металлами в районе Жирмунай г. Вильнюса. Для определения степени загрязнения дождевых стоков тяжелыми металлами от транспорта экспериментально исследовался мусор с улиц, вымываемый с дождем в реку. Также исследовались тяжелые металлы в дождевых стоках, попадающих в реку Нерис. Экспериментально с применением абсорбционно-спектрометрического метода исследовались тяжелые металлы Pb, Mn, Cr, Zn, Cu, Ni. Рассмотрен процесс анализа и результаты исследований. На основе полученных результатов составлена математическая модель распределения загрязняющих веществ в течении реки.
Дисертації з теми "Stream conservation Mathematical models"
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Romey, Bernard Timothy. "Modeling Spawning Habitat Potential for Chum (Onchorhynchus keta) and Pink Salmon (O. gorbuscha) in Relation to Landscape Characteristics in Coastal Southeast Alaska." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4252.
Повний текст джерелаАнотація:
In response to the increasing need for ecosystem services throughout the Southeast Alaska region, decision makers are tasked with balancing the need for natural resources with salmon conservation. However, accurate historical and current information on salmonid population abundance, freshwater distribution, and habitat quality are sparse with limited resolution for large portions of this remote and rugged landscape. Here, I created Intrinsic Potential (IP) models for chum and pink salmon to predict the potential for portions of coastal rivers to provide high-quality spawning habitat. I developed IP models for both species from field redd surveys and synthetic habitat variables derived from 1-m resolution digital elevation models. The surveys were performed at 49 study reaches in five coastal drainage basins on the north end of Chichagof Island, Southeast Alaska. I used a spatially balanced random sampling design that included field surveys for redds during two field seasons with contrasting precipitation patterns and disparate adult salmon escapements. The IP models predict probable spawning habitat for both species based on persistent landform characteristics and hydrologic processes that control the formation and distribution of spawning habitat across the landscape. Selection of persistent reach variables for both species IP models was informed by principal component analysis (PCA), resource selection ratios, random forest modeling, and regression models of field and synthetic variable comparisons. I observed primarily one spawning strategy by chum salmon associated with mainstem channels, and two distinct spawning strategies for pink salmon related to small moderate-gradient channels and tributaries, and lower drainage basin mainstem channels. The relationships suggest that chum and pink salmon primarily selected for unconstrained channel types in large-and small-size channels, with chum salmon being more selective toward the larger mainstem channels, and pink salmon selecting for smaller channels and tributaries. The prediction of chum salmon redd presence within a specific reach for both high and low streamflow regimes was explained by channel gradient, floodplain width, and mean annual flow in order of importance. In general, chum salmon redds were observed in larger unconstrained low-gradient floodplain reaches where accumulation of deposited gravels and adequate flow produce habitat heterogeneity suitable for spawning. Pink salmon redd presence for both survey years was explained by channel gradient, reach elevation, and mean annual flow, in order of importance. Specifically, when flows allowed upstream access, spawning pink salmon utilized smaller moderate-gradient channels where substrate size and flows were better suited to their smaller body size. Remotely sensed persistent fish habitat data is valuable information for helping understand fish population distributions across the landscape. These synthetic metrics enabled the identification and evaluation of persistent landscape features as probable predictors of IP. Validation of LiDAR-derived channel characteristics indicated channel lengths measured from the DEM were 12% longer than field measured channel length, primarily for channels wider than 10 meters. Thus, understanding the limitations of the data is important so that decision makers do not unintentionally set unrealistic objectives. This research highlights the utility of using IP models with high resolution remote sensing to expand known distributions and quality of spawning habitat for these two species in Southeast Alaska coastal streams.
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Jones, Hannah Elizabeth Mary. "Mathematical models for red squirrel conservation." Thesis, Heriot-Watt University, 2017. http://hdl.handle.net/10399/3340.
Повний текст джерелаАнотація:
In this thesis we develop mathematical models to understand the process of ecological invasion when the invading species also carries a disease that is harmful to the native species. In particular we focus on a key case study system of the invasion of grey squirrels and replacement of red squirrels in the UK, in which the shared disease, squirrelpox, has been suggested as a key driver of the rapid expansion of grey squirrels. Our initial study focused on examining the viability of red squirrels in the stronghold forests of Kidland and Uswayford in Northumberland. These are commercially managed forests that Forestry Commission England manage to improve red squirrel population viability. Through close collaboration with the Forestry Commission, we developed a mathematical model that could test squirrel population viability for a range of felling and replanting strategies. Our findings have been used to direct the forest design plans that will be implemented in these forests. Our second study used spatial, stochastic modelling techniques to model the replacement of red squirrels and subsequent control of grey squirrels on the Isle of Anglesey. Our findings indicated that the replacement of red squirrels by grey squirrels on the island was largely driven by competitive interactions. However, on a local level squirrelpox epidemics could occur and lead to mortality in red squirrel populations. Our model was also fitted to data on the control and eradication of grey squirrels and reintroduction of red squirrels that took place on the Isle of Anglesey between 1998-2013. Our fitted model was then used to examine the best conservation strategies to protect the red squirrels on Anglesey. Our final study compared key findings on the process of disease-mediated invasion in deterministic and stochastic model frameworks. The deterministic frameworks predict that a wave of disease can spread through a native population in advance of a wave of replacement of the invading species. A stochastic representation of this system indicated that this wave of disease in advance of the wave of replacement may not occur if the disease is too virulent to the native species. However, if the disease is supported by the invading species, it will still mediate the invasion at the interface between the native and invading species where local epidemic disease outbreaks can occur. In general this thesis shows that mathematical models are powerful tools for the conservation management of native species under threat from invasion.
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Ashour, Osama Naim. "Receptivity to free stream acoustic disturbances due to a roughness element on a flat plate." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09052009-040628/.
Повний текст джерела
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Vionnet, Leticia Beatriz, Thomas III Maddock, and David C. Goodrich. "Investigations of stream-aquifer interactions using a coupled surface-water and ground-water flow model." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/615700.
Повний текст джерелаАнотація:
A finite element numerical model is developed for the modeling of coupled
surface-water flow and ground-water flow. The mathematical treatment of subsurface
flows follows the confined aquifer theory or the classical Dupuit approximation for
unconfined aquifers whereas surface-water flows are treated with the kinematic wave
approximation for open channel flow. A detailed discussion of the standard approaches to
represent the coupling term is provided. In this work, a mathematical expression similar
to Ohm's law is used to simulate the interacting term between the two major hydrological
components. Contrary to the standard approach, the coupling term is incorporated
through a boundary flux integral that arises naturally in the weak form of the governing
equations rather than through a source term. It is found that in some cases, a branch cut
needs to be introduced along the internal boundary representing the stream in order to
define a simply connected domain, which is an essential requirement in the derivation of
the weak form of the ground-water flow equation. The fast time scale characteristic of
surface-water flows and the slow time scale characteristic of ground-water flows are
clearly established, leading to the definition of three dimensionless parameters, namely, a
Peclet number that inherits the disparity between both time scales, a flow number that
relates the pumping rate and the streamflow, and a Biot number that relates the
conductance at the river-aquifer interface to the aquifer conductance.
The model, implemented in the Bill Williams River Basin, reproduces the observed
streamflow patterns and the ground-water flow patterns. Fairly good results are obtained
using multiple time steps in the simulation process.
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Vionnet, Leticia Beatriz, and Leticia Beatriz Vionnet. "Investigation of stream-aquifer interactions using a coupled surface water and groundwater flow model." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187414.
Повний текст джерелаАнотація:
A finite element numerical model is developed for the modeling of coupled surface-water flow and ground-water flow. The mathematical treatment of subsurface flows follows the confined aquifer theory or the classical Dupuit approximation for unconfined aquifers whereas surface-water flows are treated with the kinematic wave approximation for open channel flow. A detailed discussion of the standard approaches to represent the coupling term is provided. In this work, a mathematical expression similar to Ohm's law is used to simulate the interacting term between the two major hydrological components. Contrary to the standard approach, the coupling term is incorporated through a boundary flux integral that arises naturally in the weak form of the governing equations rather than through a source term. It is found that in some cases, a branch cut needs to be introduced along the internal boundary representing the stream in order to define a simply connected domain, which is an essential requirement in the derivation of the weak form of the ground-water flow equation. The fast time scale characteristic of surface-water flows and the slow time scale characteristic of ground-water flows are clearly established, leading to the definition of three dimensionless parameters, namely, a Peclet number that inherits the disparity between both time scales, a flow number that relates the pumping rate and the streamflow, and a Biot number that relates the conductance at the river-aquifer interface to the aquifer conductance. The model, implemented in the Bill Williams River Basin, reproduces the observed streamflow patterns and the ground-water flow patterns. Fairly good results are obtained using multiple time steps in the simulation process.
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Ahn, Taejin 1957. "A procedure for the determination of a flow duration curve at an ungaged basin." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276585.
Повний текст джерелаАнотація:
The purpose of this study is to develop a method for predicting monthly flow duration curves for ungaged basins that are suitable for estimating average annual flow, and installed capacity and average annual energy generation at potential sites for hydropower development. The procedures were tested by developing monthly rainfall duration curves for five sample watersheds and then developing flow duration curves from the rainfall data. The methods were evaluated by comparing the predicted monthly flow duration curves to daily and monthly flow duration curves based on field data from the selected sites because a plant's potential energy output can be computed directly from a flow duration curve. The methods tested fit duration curves based on field data reasonably well and are suitable for preliminary evaluation of hydropower developments in ungaged basins.
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Kamwi, Innocent Silibelo. "Fitting extreme value distributions to the Zambezi river flood water levels recorded at Katima Mulilo in Namibia." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&.
Повний текст джерелаАнотація:
The aim of this research project was to estimate parameters for the distribution of annual maximum flood levels for the Zambezi River at Katima Mulilo. The estimation of parameters was done by using the maximum likelihood method. The study aimed to explore data of the Zambezi's annual maximum flood heights at Katima Mulilo by means of fitting the Gumbel, Weibull and the generalized extreme value distributions and evaluated their goodness of fit.
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Putnam, Douglas Alan. "Forecasting for local water management." PDXScholar, 1985. https://pdxscholar.library.pdx.edu/open_access_etds/3540.
Повний текст джерелаАнотація:
Forecast models are investigated and developed for use in local water management to aid in determining short term water requirements and availability. The forecast models include precipitation occurrence and depth using a Markov chain model, temperature and solar radiation with a multivariate autoregressive model, and streamflow with autoregressive-moving average models. The precipitation, temperature, and solar radiation forecasts are used with a soil moisture model to determine water demands. A state space approach to the Muskingum-Cunge streamflow routing technique is developed. The forecast water demands and streamflow forecasts are used as inputs to this routing model. Forecast model errors and propagation of these errors from one model into the next are investigated.
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Hofstede, Coen Matthijs. "Ice Stream Dynamics: A Transition between Sheet Flow and Shelf Flow." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/HofstedeCM2008.pdf.
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Imam, Bisher 1960. "Evaluation of disaggregation model in arid land stream flow generation." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277033.
Повний текст джерелаАнотація:
A Disaggregation model was tested for arid land stream flow generating. The test was performed on data from Black River, near Fort Apache, Arizona. The model was tested in terms of preserving the relevant historical statistics on both monthly and daily levels, the monthly time series were disaggregated to a random observation of their daily components and the daily components were then reaggregated to yield monthly values. A computer model (DSGN) was developed to perform the model implementation. The model was written and executed on the Macintosh plus personal computer Data from two months were studied; the October data represented the low flow season, while the April data represented the high flow season. Twenty five years of data for each month was used. The generated data for the two months was compared with the historical data.
Книги з теми "Stream conservation Mathematical models"
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(Korea), Chʻunchʻŏn-si. Sapʻyŏngchʻŏn hachʻŏn chŏngbi kibon kyehoek. Chʻunchʻŏn-si: Chʻunchʻŏn-si, 2003.
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(Korea), Chʻunchʻŏn-si. Kajŏngchʻŏn hachʻŏn chŏngbi kibon kyehoek pogosŏ. Chʻunchʻŏn-si: Chʻunchʻŏn-si, 2003.
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(Korea), Chʻunchʻŏn-si. Hakkokchʻŏn hachʻŏn chŏngbi kibon kyehoek pogosŏ. Chʻunchʻŏn-si: Chʻunchʻŏn-si, 2002.
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(Korea), Chʻunchʻŏn-si. Wŏlsongchʻŏn hachʻŏn chŏngbi kibon kyehoek pogosŏ. Chʻunchʻŏn-si: Chʻunchʻŏn-si, 2003.
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(Korea), Chʻunchʻŏn-si. Chibang 2-kŭp hachʻŏn Mapʻyŏngchʻŏn hachʻŏn chŏngbi kibon kyehoek. Chʻunchʻŏn-si: Chʻunchʻŏn-si, 2004.
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(Korea), Chʻunchʻŏn-si. Chʻugokchʻŏn hachʻŏn chŏngbi kibon kyehoek. Chʻunchʻŏn-si: Chʻunchʻŏn-si, 2003.
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(Korea), Chʻunchʻŏn-si. Pangdongchʻŏn hachʻŏn chŏngbi kibon kyehoek pogosŏ. Chʻunchʻŏn-si: Chʻunchʻŏn-si, 2003.
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Schloss, Alan J. A predictive model for estimating maximum summer stream temperatures in western Oregon. Springfield VA: Eugene, OR, 1985.
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(Korea), Chʻunchʻŏn-si. Kŭmsanchʻŏn hachʻŏn chŏngbi kibon kyehoek. Chʻunchʻŏn-si: Chʻunchʻŏn-si, 2002.
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(Korea), Chʻunchʻŏn-si. Sinchʻonchʻŏn hachʻŏn chŏngbi kibon kyehoek pogosŏ. [Chʻunchʻŏn-si]: Chʻunchʻŏn-si, 2003.
Знайти повний текст джерелаЧастини книг з теми "Stream conservation Mathematical models"
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Shukla, J. B., A. K. Agrawal, and B. Dubey. "Effects of Toxicants (pollutants) on a Biological Species — Some Mathematical Models." In Environmental Stress: Indication, Mitigation and Eco-conservation, 345–56. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-015-9532-2_30.
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Lim, Hyunkyung, Yan Yu, James Glimm, and David H. Sharp. "Mathematical, Physical and Numerical Principles Essential for Models of Turbulent Mixing." In Nonlinear Conservation Laws and Applications, 405–13. Boston, MA: Springer US, 2011. http://dx.doi.org/10.1007/978-1-4419-9554-4_23.
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"Weak Solutions of Conservation Laws." In Mathematical Models of Fluiddynamics, 51–68. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527602771.ch2.
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"Mathematical Models, Conservation and Constitutive Laws." In Elements of Partial Differential Equations. Berlin • New York: Walter de Gruyter, 2007. http://dx.doi.org/10.1515/9783110191240.1.
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Botsford, Louis W., J. Wilson White, and Alan Hastings. "Size-structured models." In Population Dynamics for Conservation, 122–44. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198758365.003.0005.
Повний текст джерелаАнотація:
This chapter begins by revisiting the M’Kendrick/von Foerster model, but using size instead of age as the state variable. It then uses the lessons from that model to describe how individual growth and mortality rates determine both stand distributions (a population of mixed ages) and cohort distributions (all one age). In particular, incorporating variability in growth trajectories is shown to be important in obtaining realistic results—though it is not without pitfalls. Ultimately, the numerical calculations required to model size-structured populations for future projections are more challenging than those needed for age structure, so the chapter closes by discussing some mathematical tools that have been developed to accomplish this. These include the integral projection model, a recent approach that is very useful because, while more complex, it has a lot in common with the age-structured models examined in Chapters 3 and 4.
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Johnson, Sandra, Bogdan Cristescu, Jacqueline T. Davis, Douglas W. Johnson, and Kerrie Mengersen. "Now You See Them, Soon You Won’t: Statistical and Mathematical Models for Cheetah Conservation Management." In Cheetahs: Biology and Conservation, 505–15. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-12-804088-1.00038-1.
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Cola, G. Di, G. Gilioli, and J. Baumgärtner. "Mathematical models for age-structured population dynamics: An overview." In Population and Community Ecology for Insect Management and Conservation, 45–62. CRC Press, 2020. http://dx.doi.org/10.1201/9780429333422-5.
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Botsford, Louis W., J. Wilson White, and Alan Hastings. "Spatial population dynamics." In Population Dynamics for Conservation, 214–46. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198758365.003.0009.
Повний текст джерелаАнотація:
This chapter considers populations structured in a different dimension: space. This begins by representing population dynamics with a spatial continuity equation (analogous to the M’Kendrick/von Foerster model for continuity in age or size). If organisms move at random, this motion can be approximated as diffusion. This proves useful for modeling spreading populations, such as the expansion of sea otter populations along the California coast. Adding directional advection represents a population in a flowing stream. Metapopulation models are then introduced using a simple model of the fraction of occupied patches; these are made more realistic by accounting for inter-patch distance using incidence function models. The next level of complexity is models with population dynamics in each patch. These are used to examine how metapopulations can persist as a network even if no patch would persist by itself. Finally, the consequences of synchrony (or lack thereof) among spatially separated populations is described.
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"Multispecies and Watershed Approaches to Freshwater Fish Conservation." In Multispecies and Watershed Approaches to Freshwater Fish Conservation, edited by Nicholas Sievert, Joanna B. Whittier, and Craig Paukert. American Fisheries Society, 2019. http://dx.doi.org/10.47886/9781934874578.ch5.
Повний текст джерелаАнотація:
<em>Abstract</em>.—Systematic conservation planning tools offer powerful and flexible means for addressing the protection of biodiversity in freshwater systems. Tools such as the software Zonation can be used to prioritize streams for protection, restoration, and management of aquatic resources. The flexible nature of these tools allow analyses to be tailored to specific objectives but also introduces uncertainty regarding the effects of selected input options on the rankings of stream segments and the representation of fish species within prioritized streams. The objective of our research was to evaluate the effectiveness of several species distribution modeling techniques (generalized additive models, multivariate adaptive regression splines, boosted regression trees, and random forest models, including an ensemble based on these techniques) for characterizing distributions of fish communities and to identify the influence of different prioritization options of Zonation conservation planning software within five input classes (species occurrence data, removal rule, species weighting, connectivity, and protected area masking) on both the resulting stream segment rankings and the representation of species within priority streams. All combinations of input options were compared based on the correlation and congruence of stream rankings and the mean richness of species, minimum level of species representation, and representation of rare species within streams across priority levels. Of the distribution modeling types we evaluated, boosted regression trees performed the best, followed closely by random forest models. The use of an ensemble approach allowed for the largest number of species with robust predicted distributions. Our results also suggested that protected area masking had the largest effects on conservation priority results, followed by choice of removal rule, while species occurrence data type had limited impacts. The information contained in this chapter is meant to aid planners in understanding how their selection of conservation planning inputs is likely to impact results.
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"Landscape Influences on Stream Habitats and Biological Assemblages." In Landscape Influences on Stream Habitats and Biological Assemblages, edited by James E. McKenna, Richard P. McDonald, Chris Castiglione, Sandy S. Morrison, Kurt P. Kowalski, and Dora R. Passino-Reader. American Fisheries Society, 2006. http://dx.doi.org/10.47886/9781888569766.ch26.
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<em>Abstract.</em>—We describe a methodology for developing species–habitat models using available fish and stream habitat data from New York State, focusing on the Genesee basin. Electrofishing data from the New York Department of Environmental Conservation were standardized and used for model development and testing. Four types of predictive models (multiple linear regression, stepwise multiple linear regression, linear discriminant analysis, and neural network) were developed and compared for 11 fish species. Predictive models used as many as 25 habitat variables and explained 35–91% of observed species abundance variability. Omission rates were generally low, but commission rates varied widely. Neural network models performed best for all species, except for rainbow trout <em>Oncorhynchus mykiss</em>, gizzard shad <em>Dorosoma cepedianum</em>, and brown trout <em>Salmo trutta</em>. Linear discriminant functions generally performed poorly. The species–environment models we constructed performed well and have potential applications to management issues.
Тези доповідей конференцій з теми "Stream conservation Mathematical models"
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Killion, J. D., and S. Garimella. "Performance Predictions of a Moisture Management Device for Fuel Cell Applications." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14652.
Повний текст джерелаАнотація:
Moisture management in proton-exchange-membrane fuel cells is crucial to durability and performance. This frequently requires external humidification of the reactant gas streams to maintain sufficient humidity levels at the membranes, especially at higher operating temperatures. Direct-contact humidifiers using louvered fins brazed to rectangular tubes, similar to those frequently employed in automotive condensers and radiators, can be used to humidify a gas stream. A gas stream in which liquid water is sprayed flows through the passages formed by the louvered fins counter-current to a heating fluid flowing in the rectangular tubes sandwiching the fins. A mathematical model of this type of direct-contact humidifier is presented. The equations of energy and mass conservation are simultaneously solved for a number of segments along the humidifier. An equivalent resistance network is used to capture the temperature profile of the fins and liquid film surrounding them. The thickness of the liquid film is calculated from a shear balance at the film interface. The heat and mass transfer analogy is used with empirically derived transfer coefficients to solve the coupled heat and mass transfer problem in the gas phase. Predicted results are presented for typical operating conditions corresponding to a wide range of fuel cell operating conditions. The results show how the humidification process varies along the length of the humidifier. It is also shown that, although evaporation of the liquid film takes place throughout the entire humidifier, the direction of sensible heat transfer between the gas and liquid film can switch at some distance along the humidifier. This confirms the need for the equivalent resistance network model of the fin and film since simple fin efficiency models would fail in this situation. The model provides a basis for design optimization and performance predictions for this type of direct-contact moisture management device.
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Kombarov, Sayan. "Action in Economics: Mathematical Derivation of Laws of Economics from the Principle of Least Action in Physics." In International Conference on Eurasian Economies. Eurasian Economists Association, 2021. http://dx.doi.org/10.36880/c13.02498.
Повний текст джерелаАнотація:
The thesis of this paper is mathematical formulation of the laws of Economics with application of the principle of Least Action of classical mechanics. This paper is proposed as the rigorous mathematical approach to Economics provided by the fundamental principle of the physical science – the Principle of Least Action. This approach introduces the principle of Action into main-stream economics and allows reconcile main principles Austrian School of Economics and the laws of market, such Say’s law and marginal value and interest rate theory, with the modern results of mathematical economics, such as Capital Asset Pricing Model (CAPM), game theory and behavioral economics. This principle is well known in classical mechanics as the law of conservation of action that governs any system as a whole and all its components. It led to the revolution in physics, as it allows to derive the laws of Newtonian and quantum mechanics and probability. Ludwig von Mises defined Economics is the science of Human Action. Action is introduced into Economics by the founder of Austrian School of Economic, Carl Menger. Production or acquisition of any goods, services and assets are results of purposeful acts in the form of expenditure of work and energy in the form of flow of money and material resources. Humans take them to achieve certain desired goals with given resources and time. Any economic good and service, financial, productive, or real estate asset is the result of such action.
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Chen, Chin-Lung, and Chin-Hsiang Cheng. "Natural Convection Heat Transfer and Flow Pattern in an Inclined Arc-Shape Enclosure." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24122.
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Abstract Numerical and experimental investigations have been conducted to study the flow and heat transfer characteristics for the buoyancy-induced flow inside an inclined arc-shape enclosure. Mathematical model in form of a stream function-vorticity formulation representing the laws of conservation in mass, momentum, and energy is expressed in a curvilinear coordinate frame and solved by a finite-volume discretization method. Heat transfer and flow pattern are predicted at various Grashof numbers and inclination angles. Meanwhile, an experimental system is developed and a flow-visualization technique using smoke is employed to observe the flow pattern. Results show that when the Grashof number is higher than 105, the increase in natural convection heat transfer becomes appreciable. The vortex strength and pattern are found to be greatly dependent on the inclination angle. The range of the Grashof number considered in this study is up to 107 and the inclination angle is varied from 0 to π.
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Lortz, Wolfgang, and Radu Pavel. "Advanced Modeling of Drilling – Realistic Process Mechanics Leading to Helical Chip Formation." In ASME 2021 16th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/msec2021-63790.
Повний текст джерелаАнотація:
Abstract There is considerable interest in the “Industry 4.0 project”. Industry hopes that a general solution of the metal removal problem will be found through the use of highly automated manufacturing data. Scientists hope that the computer will provide better models based on artificial intelligence and machine learning. Initial attempts leveraging existing models did not result in satisfactory results yet — largely because of mathematical, physical and metallurgical reasons. This paper presents a new mathematical-physical model to describe the total process mechanics from volume conservation, to friction, to metal plasticity with self-hardening or softening effects and dynamic phenomena during metal plastic flow. The softening effects are created by high energy corresponding to high strain-rate resulting in high temperatures. Furthermore, the developed equations for strain-rate discontinuities as well as yield shear stress with body forces have an interdependent relationship and lead to plastic deformation with dynamic behavior in the total chip formation zone. This plastic deformation is the only parameter that will not disappear after completing the process. This leads to the opportunity to check the theoretically developed grid deformation and compare it with practical results of the same area. In this publication this new theory will be used to analyze the complex contact and friction conditions between the chip and tool edge of a twist drill during operation. It will be shown that the existing conditions are leading to high wear at the corner edge and flank wear at the tool cutting edge. In addition, the existing temperatures can be estimated and compared with practical measurements, and all these complex and difficult conditions create a helical spiral chip, which could be developed as it will be presented in this paper.
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Peshkov, Ilya, Miroslav Grmela, and Evgeniy Romenski. "Two-Phase Solid-Fluid Mathematical Model of Yield Stress Fluids." In ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-7913.
Повний текст джерелаАнотація:
In this work, we present results on mathematical modelling of polymeric yield stress fluids which have the properties of both elastic solids and fluids. Our research is based on the approach of multiphase continuum mechanics. A two-phase solid-fluid model is developed. This model is thermodynamically compatible and its governing differential equations can be written in a conservative form. Such a model is convenient for application of advanced high-accuracy numerical methods and modelling of discontinuous solutions such as shock waves and contacts.
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Alsaleem, Naors Y. Anad, Riyad Mubarak Abdullah, and Maan Y. Anad Alsaleem. "Mathematical models of peer to peer networks for stream IPTV transmission." In 2018 IEEE 9th International Conference on Dependable Systems, Services and Technologies (DESSERT). IEEE, 2018. http://dx.doi.org/10.1109/dessert.2018.8409110.
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Franco, Fermin, and Yasuhide Fukumoto. "Mathematical models for turbulent round jets based on “ideal” and “lossy” conservation of mass and energy." In ILASS2017 - 28th European Conference on Liquid Atomization and Spray Systems. Valencia: Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/ilass2017.2017.4778.
Повний текст джерелаАнотація:
We propose mathematical models for turbulent round atomized liquid jets that describe its dynamics in a simplebut comprehensive manner with the apex angle of the cone being the main disposable parameter. The basic assumptions are that (i) the jet is statistically stationary and that (ii) it can be approximated by a mixture of two fluids with the phases in local dynamic equilibrium, or so-called locally homogeneous flow (LHF). The models differ in their particular balance of explanatory capability and precision. To derive them we impose partial conservation of the initial mass and energy fluxes, introducing loss factors again as disposable parameters. Depending on each model, the equations admit explicit or implicit analytical solutions or a numerical solution in the discretized model case. The described variables are the the two-phase fluid’s composite density and velocity, both as functions of thedistance from the nozzle, from which the dynamic pressure is calculated.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4778
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Du, Dongxiao, Guanghui Su, and Suizheng Qiu. "Theoretical Calculation of the Critical Heat Flux in Annular Upward Flow in Vertical Narrow Rectangular Channels." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75149.
Повний текст джерелаАнотація:
The present paper has developed a mathematical separated flow model for annular upward flow in vertical narrow rectangular channels to predict the critical heat flux. The theoretical model is based on fundamental conservation principles: the mass, momentum, and energy conservation equation of liquid film and the momentum conservation equation of vapor core together with a set of closure relationships (such as entrainment rate, deposition rate, interfacial shear stress and initial entrainment fraction at the onset of annular flow). The predicted results are compared with the experimental data and fairly good agreement between them is achieved. By numerically solving the equations, liquid film thickness, liquid film velocity in the liquid film and heat transfer coefficient are obtained. With the applications of the present model, the critical heat flux in the rectangular channel is calculated and analyzed.
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Bhattacharya, Anindya. "Stress Analysis of Pipe Support Attachments: A Comparison of Analytical Methods and Finite Element Analysis for Circular and Non-Circular Attachments." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97622.
Повний текст джерелаАнотація:
Despite the availability of special purpose FE codes with post processing facilities as per rules of ASME SEC VIII Division 2, use of simple analytical methods like ring loading around a circumference or more complex methods like Welding Research council bulletins 107 and 297, will continue to be used in the industry for a significant period of time for stress analysis of pipe support attachments. The reasons are few: not all engineering companies have such custom made FE codes, lack of trained personnel to work with general purpose FE codes, ease of implementation of the available methods and their successful design history, cost and time issues with FE analysis etc. In this paper these available methods will be reviewed based on their theoretical background, their range of applicability w.r.t the typical design parameters and their comparison with FE analysis. More recent analytical methods based on mathematically accurate space curves of intersections for circular attachments will also be discussed. This study will include both circular as well as non-circular attachments. This paper will highlight the strengths and weaknesses of the conventionally used methods especially with respect to their mathematical limitations to make an analyst aware of the potential over conservatism and under conservatism of these analytical methods. Finite element analysis models will be discussed in detail specifically in relation to elements used, element parameters, boundary conditions and post processing.
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Onyejekwe, Ogugua, Amir Yousef Sajjadi, Ugur Abdulla, Kunal Mitra, and Michael Grace. "Mathematical Models for Analyzing Tissue Ablation Using Short Pulse Lasers." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11626.
Повний текст джерелаАнотація:
Mathematical modeling of biological tissue ablation performed using a short pulse laser and the corresponding experimental analysis is of fundamental importance to the understanding and predicting the temperature distribution and heat affected zone for advancing surgical application of lasers. The objective of this paper is to use mathematical models to predict the thermal ablated zones during irradiation of freshly excised mouse skin tissue samples by a novel approach using a focused laser beam from a short pulse laser source. Suggested mathematical model is Stefan kind free boundary problem for the heat equation in unknown region. Temperature of the skin satisfies the classical heat equation subjected to Neumann boundary condition on the known boundary, while along the time-dependent unknown boundary, which characterizes the ablation depth, two conditions are met: (1) temperature is equal to the ablation temperature and (2) classical Stefan condition is satisfied. The latter expresses the conservation of energy at the ablation moment. A method of integral equations is used to reduce the Stefan problem to a system of two Volterra kind integral equations for temperature and ablation depth. MATLAB is used subsequently for the numerical solution. Experiments are performed using two lasers—a diode laser having a wavelength of 1552 nm and pulsewidth of 1.3 ps. The surface temperature distribution is measured using an imaging camera. After irradiation, histological studies of laser irradiated tissues are performed using frozen sectioning technique to determine the extent of thermal damage caused by the laser beam. The ablation depth and width is calculated based on the interpolated polygon technique using image processing software. The surface temperature distribution and the ablation depth obtained from the mathematical models are compared with the experimental measurements and are in very good agreement. A parametric study of various laser parameters such as time-average power, pulse repetition rate, pulse energy, and irradiation time is performed to determine the necessary ablation threshold parameters.
Звіти організацій з теми "Stream conservation Mathematical models"
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Pruitt, Bruce, K. Killgore, William Slack, and Ramune Matuliauskaite. Formulation of a multi-scale watershed ecological model using a statistical approach. Engineer Research and Development Center (U.S.), November 2020. http://dx.doi.org/10.21079/11681/38862.
Повний текст джерелаАнотація:
The purpose of this special report is to provide a statistical stepwise process for formulation of ecological models for application at multiple scales using a stream condition index (SCI). Given the global variability of aquatic ecosystems, this guidance is for broad application and may require modification to suit specific watersheds or stream reaches. However, the general statistical treatise provided herein applies across physiographies and at multiple scales. The Duck River Watershed Assessment in Tennessee was used, in part, to develop and test this multiscale, statistical approach; thus, it is considered a case example and referenced throughout this report. The findings of this study can be utilized to (1) prioritize water-sheds for restoration, enhancement, and conservation; (2) plan and conduct site-specific, intensive ecosystem studies; and (3) assess ecosystem outcomes (that is, ecological lift) applicable to future with and without restoration actions including alternative, feasibility, and cost-benefit analyses and adaptive management.