Academic literature on the topic 'Stream conservation Mathematical models'
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Journal articles on the topic "Stream conservation Mathematical models"
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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.
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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.
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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 (2019): 224–29. http://dx.doi.org/10.55176/2414-1038-2019-1-224-229.
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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.
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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 (2021): 17–22. http://dx.doi.org/10.20914/2310-1202-2021-1-17-22.
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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.
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Latipov, Nusratilla, Dilbar Abduraimova, Zaytuna Ibragimova, Makhsud Otakhonov, and M. Hamdamov. "Numerical simulation of combustion processes." E3S Web of Conferences 401 (2023): 03072. http://dx.doi.org/10.1051/e3sconf/202340103072.
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In this paper, we propose a numerical method for solving the problem of the propagation and combustion of a methane jet in an axisymmetric satellite air flow. Within the framework of the modified turbulence model and the Arrhenius law, mathematical and numerical models of the problem of a turbulent axisymmetric methane jet in an infinite cocurrent air flow at a finite reaction rate have been developed. By introducing functions and generalized Schwab-Zel'dovich functions, as well as the stream function, ten differential equations for the conservation of substances are represented by differential equations equivalent to them. The equations of the turbulent boundary layer of a multicomponent gas for an axisymmetric jet are transformed with the transition to dimensionless variables and the introduction of a stream function. The dimensionless equations of the turbulent boundary layer of reacting gases in von Mises coordinates are used for modeling. For the numerical solution of the combustion problem according to the Arrhenius law, an implicit finite-difference scheme was used, which provides the second order of approximation accuracy in longitudinal and transverse coordinates. This made it possible to significantly reduce the calculation time as a result of using a large calculation step for the longitudinal coordinate. In connection with the nonlinearity of the equations of conservation and transfer of substances, an iterative process was organized. Some results of the computational experiment are presented. Comparison of the results of calculating the change in the temperature of the axial flow according to the turbulence models modified by k − ε and Prandtl with experimental data. The adequacy of the results was verified by the implementation of the laws of conservation of mass, momentum and total enthalpy, as well as by comparing the results with experimental data from other authors with the largest 5% deviation. This means that the previously presented algorithm and calculation program can be used for practical purposes. The results obtained with both turbulence models were compared with experimental data. Analyzing the results, one can notice that the k − ε model coincides more qualitatively with the experiment than the Prandtl turbulence model.
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Colognesi, Victor, Renaud Ronsse, and Philippe Chatelain. "Numerical assessment of wake-based estimation of instantaneous lift in flapping flight of large birds." PLOS ONE 18, no. 5 (2023): e0284714. http://dx.doi.org/10.1371/journal.pone.0284714.
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Experimental characterization of bird flight without instrumenting the animal requires measuring the flow behind the bird in a wind tunnel. Models are used to link the measured velocities to the corresponding aerodynamic forces. Widely-used models can, however, prove inconsistent when evaluating the instantaneous lift. Yet, accurately estimating variations of lift is critical in order to reverse-engineer flapping flight. In this work, we revisit mathematical models of lift based on the conservation of momentum in a control volume around a bird. Using a numerical framework to represent a flapping bird wing and compute the flow around it, we mimic the conditions of a wind tunnel and produce realistic wakes, which we compare to experimental data. Providing ground truth measurements of the flow everywhere around the simulated bird, we assess the validity of several lift estimation techniques. We observe that the circulation-based component of the instantaneous lift can be retrieved from measurements of velocity in a single plane behind a bird, with a latency that is found to depend directly on the free-stream velocity. We further show that the lift contribution of the added-mass effect cannot be retrieved from such measurements and quantify the level of approximation due to ignoring this contribution in instantaneous lift estimation.
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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.
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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.
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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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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.
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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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Lutz, Stefanie R., Ype van der Velde, Omniea F. Elsayed, et al. "Pesticide fate on catchment scale: conceptual modelling of stream CSIA data." Hydrology and Earth System Sciences 21, no. 10 (2017): 5243–61. http://dx.doi.org/10.5194/hess-21-5243-2017.
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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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Lutz, S. R., Y. V. D. Velde, O. F. Elsayed, et al. "Pesticide fate on catchment scale: conceptual modelling of stream CSIA data." Hydrology and Earth System Sciences 21, no. 10 (2017): 5243–61. https://doi.org/10.5194/hess-21-5243-2017.
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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<sup>−1</sup>) in response to an intense rainfall event following herbicide application. Increasing <i>δ</i><sup>13</sup>C 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 <i>δ</i><sup>13</sup>C 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.
Dissertations / Theses on the topic "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.
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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.
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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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MANTELLI, ELISA. "Mathematical Models of ice stream dynamics and supraglacial drainage." Doctoral thesis, Politecnico di Torino, 2016. http://hdl.handle.net/11583/2640231.
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Patterning is a recurrent feature of glacial systems, which characterizes as much subglacial and supraglacial environments as the flow of ice itself. Some examples include bedforms developing at the contact between ice and bed, spatial organization in subglacial and supraglacial drainage networks, the narrow corridors of fast flowing ice known as ice streams that form the arterial drainage system of large ice sheets, and temporal switches between slow and fast flow regimes in glacier and ice stream flow. This thesis focusses on two types of glacial patterns, namely ice streams and channelization in supraglacial drainage networks.
Ice flow within ice sheets is far from uniform, with the narrow bands known as ice streams flowing at velocity two order of magnitude larger than the rest of the ice sheet. In the Siple Coast region of West Antarctica ice streams experiance weak topographic confinement, thus suggesting that they may originate spontaneously from an otherwise uniform flow as a fingering instability. Motivated by observations suggesting that the marked contrast in velocity between ice streams and surrounding ice is due to a transition from frozen, thus sticky bed underneath slow flowing regions, to molten, thus well lubricated bed under ice streams, we investigate the role of basal thermal transitions in relation to the onset of ice streams. Our findings suggest that basal transitions from frozen to molten bed (or vice versa) can undergo an instability potentially leading to the onset of streaming. An asymptotic analysis for short wavelenght perturbations shows that, at wavelengths of few ice thicknesses, such instability is controlled by the interplay between strain heating and heat advection from the region upstream of the transition. We also find that the background structure of the ice sheet is key to pattern formation. In particular, in the case of ice flowing from molten to frozen regions we find an instability at the ice sheet thickness scale or smaller, which is not resolved by most ice sheet models.
Observations reveal that ice streams experience significant temporal variability on a variety of time scales, ranging from decadal to multi-millennial ones. As much as spatial patterning, such variability holds implications for the future of ice sheets, sea level change, and the interpretation of geological records. Recent work \citep{robel} shows that the switch between steady streaming conditions and self-sustained oscillations with multi-millennial periodicity can be understood as a Hopf bifurcation. Little is presently known about shorter scale variability, which however appears more likely to originate from external forcing. In chapter \ref{ch:stoch} we explore the effects of a specific type of forcing, i.e. stochastically-varying climatic conditions, on the temporal dynamics of ice stream flow. We find that data-based climate fluctuations alter the deterministic dynamics substantially, and are capable of introducing widespread, short-scale oscillations even in ranges of the parametric regime where the deterministic dynamics predict steady streaming. We thus conclude that noise-induced transitions may play a role in the observed temporal dynamics of ice stream flow.
In part \ref{drain} we turn to patterning in drainage networks on the surface of glaciers. Supraglacial drainage networks route meltwater originating on the surface of glaciers towards moulins and crevasses, through which it eventually reaches the base of the ice. Therefore, understanding the physical controls on the structure of the drainage network has implications for how surface melt influences the motion of ice. Here we focus on the physical controls on the formation of evenly spaced channels on the surface of glaciers. In particular, we find that the flow of meltwater on bare ice is capable of carving evenly spaced channels as a result of a morphological instability. We show that in certain conditions the network is shaped solely by the hydrodynamics of meltwater regardless of ice thermal conditions, which justifies widely-observed regular patterns in drainage networks. Finally, comparison of our results with the geometrical feature of supraglacial networks reported in the literature shows good agreement between model's predictions and observations.
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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/.
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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.
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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.
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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.
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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&.
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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.
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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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Fournet, Victor. "Mathematical and Numerical Study of Thick Spray Models." Electronic Thesis or Diss., Sorbonne université, 2025. http://www.theses.fr/2025SORUS024.
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Cette thèse est consacrée à la modélisation, à l'analyse mathématique et à l'analyse numérique d'un système d'équations aux dérivées partielles décrivant l'évolution d'une suspension de par- ticules neutres dans un fluide ambiant, souvent désignée sous le nom de spray. La phase dispersée est modélisée par les équations de la théorie cinétique, tandis que la phase continue est décrite par les équations de la mécanique des fluides. Nous nous concentrons en particulier sur le cas des sprays dits épais. Le chapitre 2 est consacré au problème de la construction de solutions pour le système des sprays épais. Nous introduisons un nouveau système dans lequel les termes singuliers sont régularisés et nous démontrons l'existence et l'unicité de solutions avec une régularité de type Sobolev, localement en temps. Le chapitre 3 explore l'analogie entre le système des sprays épais et le système de Vlasov- Poisson décrivant un plasma électrostatique. Nous montrons qu'en l'absence de friction, le système des sprays épais présente une propriété d'amortissement linéaire de l'énergie acoustique, analogue à l'amortissement de Landau bien connu en physique des plasmas. Cet effet est illustré par des résultats numériques. Le chapitre 4 est consacré à la simulation numérique du système des sprays épais. Nous proposons une approche combinant des méthodes existantes : une méthode semi-Lagrangienne pour la phase dispersée, couplée à une méthode de type Volume Fini pour la phase continue. Nous abordons également le problème de la limite de packing et introduisons deux méthodes permettant de conserver cette limite au niveau discret. Enfin, nous présentons des résultats numériques<br>This thesis is dedicated to the modeling, mathematical analysis, and numerical analysis of a partial differential equation system describing the evolution of a suspension of neutral particles in a surrounding fluid, often referred to as a spray. The dispersed phase is modeled by the equations of kinetic theory, while the continuous phase is described by the equations of fluid mechanics. We focus particularly on the case of so-called dense sprays.Chapter 2 is devoted to the problem of constructing solutions for the dense spray system. We introduce a new system in which singular terms are regularized, and we prove the existence and uniqueness of solutions with Sobolev regularity, locally in time.Chapter 3 explores the analogy between the dense spray system and the Vlasov-Poisson system describing an electrostatic plasma. We demonstrate that, in the absence of friction, the dense spray system exhibits a property of linear damping of acoustic energy, analogous to Landau damping, which is well known in plasma physics. This effect is illustrated by numerical results.Chapter 4 is dedicated to the numerical simulation of the dense spray system. We present an approach that combines existing methods: a semi-Lagrangian method for the dispersed phase, coupled with a finite volume method for the continuous phase. We also address the packing limit issue and introduce two methods to preserve this packing limit at the discrete level. Finally, we present numerical results
Books on the topic "Stream conservation Mathematical models"
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(Korea), Chʻunchʻŏn-si. Kajŏngchʻŏn hachʻŏn chŏngbi kibon kyehoek pogosŏ. Chʻunchʻŏn-si, 2003.
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(Korea), Chʻunchʻŏn-si. Wŏlsongchʻŏn hachʻŏn chŏngbi kibon kyehoek pogosŏ. Chʻunchʻŏn-si, 2003.
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(Korea), Chʻunchʻŏn-si. Sapʻyŏngchʻŏn hachʻŏn chŏngbi kibon kyehoek. Chʻunchʻŏn-si, 2003.
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(Korea), Chʻunchʻŏn-si. Hakkokchʻŏn hachʻŏn chŏngbi kibon kyehoek pogosŏ. Chʻunchʻŏn-si, 2002.
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(Korea), Chʻunchʻŏn-si. Chibang 2-kŭp hachʻŏn Mapʻyŏngchʻŏn hachʻŏn chŏngbi kibon kyehoek. Chʻunchʻŏn-si, 2004.
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(Korea), Chʻunchʻŏn-si. Pangdongchʻŏn hachʻŏn chŏngbi kibon kyehoek pogosŏ. Chʻunchʻŏn-si, 2003.
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(Korea), Chʻunchʻŏn-si. Chʻugokchʻŏn hachʻŏn chŏngbi kibon kyehoek. Chʻunchʻŏn-si, 2003.
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Schloss, Alan J. A predictive model for estimating maximum summer stream temperatures in western Oregon. Eugene, OR, 1985.
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(Korea), Chʻunchʻŏn-si. Sinchʻonchʻŏn hachʻŏn chŏngbi kibon kyehoek pogosŏ. Chʻunchʻŏn-si, 2003.
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(Korea), Chʻunchʻŏn-si. Kŭmsanchʻŏn hachʻŏn chŏngbi kibon kyehoek. Chʻunchʻŏn-si, 2002.
Find full textBook chapters on the topic "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. 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. Springer US, 2011. http://dx.doi.org/10.1007/978-1-4419-9554-4_23.
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Feistauer, M., J. Felcman, and I. Straskraba. "Finite Difference and Finite Volume Methods for Nonlinear Hyperbolic Systems and the Euler Equations." In Mathematical and Computational Methods for Compressible Flow. Oxford University PressOxford, 2003. http://dx.doi.org/10.1093/oso/9780198505884.003.0004.
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Abstract In modern technologies one often encounters the necessity to solve compressible flow with a complicated structure. There are several conceivable models of compressible flow. Let us mention, for example, the model of inviscid, stationary, irrotational or rotational subsonic flow using the stream function formulation, and the models of transonic flow based on the small perturbation equation or full potential equation. There exists an extensive literature about the finite difference or finite element methods for the numerical solution of these models. (For a survey of mathematical and numerical methods for these models, see (Feistauer, 1998).) In a number of problems, the potential models are not sufficiently accurate, particularly in high speed (transonic or hypersonic) flow, because of the appearance of the so-called strong shocks with large entropy and vorticity production. This leads to the necessity of using the complete system of conservation laws consisting of the continuity equation, the Euler equations of motion and the energy equation (called the Euler equations in brief), which has been widely used during the last few decades for the modelling of flows in aeronautics, the aviation industry and steam or gas turbine design. Successively, the Euler equations have begun to be applied also to low Mach number problems on the one hand and to problems with chemical reactions on the other. These models neglect, of course, viscosity, but in many situations they give good results, reliable from the point of view of comparisons with experiments.
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"Weak Solutions of Conservation Laws." In Mathematical Models of Fluiddynamics. 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. Walter de Gruyter, 2007. http://dx.doi.org/10.1515/9783110191240.1.
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David, T., S. Thomas, and P. G. Walker. "Platelet Deposition in Stagnation Point Flow: An Analytical Study and Computational Simulation." In Cardiovascular Flow Modelling and Measurement with Application to Clinical Medicine. Oxford University PressOxford, 1999. http://dx.doi.org/10.1093/oso/9780198505204.003.0005.
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Abstract A mathematical and numerical model is developed for the adhesion of platelets in steady stagnation point flow. The model provides for a correct representation of the axi-symmetric flow and explicitly uses shear rate to characterise not only the convective transport but also the simple reaction mechanism used to model platelet adhesion at the wall surface. Excellent agreement exists between the analytical solution and that obtained by the numerical integration of the full Navier-Stokes equations and decoupled conservation of species equations. It has been shown that for a constant wall reaction rate modelling platelet adhesion the maximum platelet flux occurs at the stagnation point streamline. This is in direct contrast to that found in experiment where the maximum platelet deposition occurs at some distance downstream of the stagnation point. However, if the wall reaction rate is chosen to be linearly dependent on the wall shear stress then the results show that the maximum platelet flux occurs downstream of the stagnation point, providing a more realistic model of experimental evidence. The first stage of thrombogenesis is platelet adhesion. This may then be followed by platelet aggregation and the formation of mural thrombi [2] and [3]. Although the formation of thrombi in stasis is fairly well understood the influence of blood flow characteristics has yet to be fully investigated. Fluid dynamic studies of blood flow, in models of arteries, suggests a set of fluid dynamic conditions which appear to predispose thrombus formation, principally at arterial bifurcations [7], T-junctions and curved sections, in particular, Schoepheoster and Dewanjee [15] found that areas of flow stagnation or recirculation are shown to promote thrombus formation.
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Botsford, Louis W., J. Wilson White, and Alan Hastings. "Size-structured models." In Population Dynamics for Conservation. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198758365.003.0005.
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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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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. CRC Press, 2020. http://dx.doi.org/10.1201/9780429333422-5.
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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. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-12-804088-1.00038-1.
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Botsford, Louis W., J. Wilson White, and Alan Hastings. "Spatial population dynamics." In Population Dynamics for Conservation. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198758365.003.0009.
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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.
Conference papers on the topic "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.
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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.
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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.
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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.
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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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Korniienko, Valentyn, Lina Larchenko, Anzhelika Parkhomenko, and Bogdan Larchenko. "Design Models of Bit-Stream Online-Computers of Elementary Mathematical Functions." In 2023 IEEE 12th International Conference on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications (IDAACS). IEEE, 2023. http://dx.doi.org/10.1109/idaacs58523.2023.10348885.
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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.
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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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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. Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/ilass2017.2017.4778.
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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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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.
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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.
Reports on the topic "Stream conservation Mathematical models"
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Equihua, M., and O. Perez-Maqueo. Mathematical Modeling and Conservation. American Museum of Natural History, 2010. http://dx.doi.org/10.5531/cbc.ncep.0154.
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Formal models are indispensable tools in natural resource management and in conservation biology. Explicit modeling can be a helpful tool for studying these systems, communicating across disciplines, and integrating varying viewpoints of numerous stakeholders. This module demonstrates how to explicitly construct models as alternative representations to help interpret and understand nature. Through a synthesis and two exercises, it describes the general context of scientific modeling (i.e., use and types of models), and allows students to practice building a model by evaluating the relationship between rabbit and fox population dynamics - from stating the problem, constructing a dynamic hypothesis, and formulating and testing the model.
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Gibbs, James. Applied Demography. American Museum of Natural History, 2006. http://dx.doi.org/10.5531/cbc.ncep.0173.
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Applied demography involves using the knowledge gained from analyzing and understanding populations in order to manage them effectively. The synthesis reviews basic concepts of demography and their application to management of wild populations. There are several major drivers of population change that operate in different ways, including birth rates, death rates, changes in sex ratios, and migration. These concepts can be formalized into mathematical population models that can be used to make predictions about populations under different management scenarios. Four case studies (including the Giant Galápagos Tortoise) are used to illustrate the real-world application of demographic concepts to rare species conservation.
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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.), 2020. http://dx.doi.org/10.21079/11681/38862.
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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.