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transcritical</title> <meta name="description" content="Search results for: transcritical"> <meta name="keywords" content="transcritical"> <meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1, user-scalable=no"> <meta charset="utf-8"> <link href="https://cdn.waset.org/favicon.ico" type="image/x-icon" rel="shortcut icon"> <link href="https://cdn.waset.org/static/plugins/bootstrap-4.2.1/css/bootstrap.min.css" rel="stylesheet"> <link href="https://cdn.waset.org/static/plugins/fontawesome/css/all.min.css" rel="stylesheet"> <link href="https://cdn.waset.org/static/css/site.css?v=150220211555" rel="stylesheet"> </head> <body> <header> <div class="container"> <nav class="navbar navbar-expand-lg navbar-light"> <a class="navbar-brand" href="https://waset.org"> <img src="https://cdn.waset.org/static/images/wasetc.png" alt="Open Science Research Excellence" title="Open Science Research Excellence" /> </a> <button class="d-block d-lg-none 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action="https://publications.waset.org/abstracts/search"> <div id="custom-search-input"> <div class="input-group"> <i class="fas fa-search"></i> <input type="text" class="search-query" name="q" placeholder="Author, Title, Abstract, Keywords" value="transcritical"> <input type="submit" class="btn_search" value="Search"> </div> </div> </form> </div> </div> <div class="row mt-3"> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Commenced</strong> in January 2007</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Frequency:</strong> Monthly</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Edition:</strong> International</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Paper Count:</strong> 10</div> </div> </div> </div> <h1 class="mt-3 mb-3 text-center" style="font-size:1.6rem;">Search results for: transcritical</h1> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">10</span> Thermodynamic Optimization of an R744 Based Transcritical Refrigeration System with Dedicated Mechanical Subcooling Cycle</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Mihir%20Mouchum%20Hazarika">Mihir Mouchum Hazarika</a>, <a href="https://publications.waset.org/abstracts/search?q=Maddali%20Ramgopal"> Maddali Ramgopal</a>, <a href="https://publications.waset.org/abstracts/search?q=Souvik%20Bhattacharyya"> Souvik Bhattacharyya</a> </p> <p class="card-text"><strong>Abstract:</strong></p> The thermodynamic analysis shows that the performance of the R744 based transcritical refrigeration cycle drops drastically for higher ambient temperatures. This is due to the peculiar s-shape of the isotherm in the supercritical region. However, subcooling of the refrigerant at the gas cooler exit enhances the performance of the R744 based system. The present study is carried out to analyze the R744 based transcritical system with dedicated mechanical subcooling cycle. Based on this proposed cycle, the thermodynamic analysis is performed, and optimum operating parameters are determined. The amount of subcooling and the pressure ratio in the subcooling cycle are the parameters which are needed to be optimized to extract the maximum COP from this proposed cycle. It is expected that this study will be helpful in implementing the dedicated subcooling cycle with R744 based transcritical system to improve the performance. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=optimization" title="optimization">optimization</a>, <a href="https://publications.waset.org/abstracts/search?q=R744" title=" R744"> R744</a>, <a href="https://publications.waset.org/abstracts/search?q=subcooling" title=" subcooling"> subcooling</a>, <a href="https://publications.waset.org/abstracts/search?q=transcritical" title=" transcritical"> transcritical</a> </p> <a href="https://publications.waset.org/abstracts/65947/thermodynamic-optimization-of-an-r744-based-transcritical-refrigeration-system-with-dedicated-mechanical-subcooling-cycle" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/65947.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">306</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">9</span> Generation Transcritical Flow Influenced by Dissipation over a Hole</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Mohammed%20Daher%20Albalwi">Mohammed Daher Albalwi</a> </p> <p class="card-text"><strong>Abstract:</strong></p> The transcritical flow of a stratified fluid over an obstacle for negative forcing amplitude (hole) that generation upstream and downstream, connected by an unsteady solution, is examined. In the weakly nonlinear, weakly dispersive regime, the problem is formulated in the forced Korteweg-de Vries–Burgers framework. This is done by including the influence of the viscosity of the fluid beyond the Korteweg–de Vries approximation. The results show that the influence of viscosity is crucial in determining various wave properties, including the amplitudes of solitary waves in the upstream and downstream directions, as well as the widths of the bores. We focused here on weak damping, and the results are presented for transcritical, supercritical, and subcritical flows. In general, the outcomes are not qualitatively similar to those from the forced Korteweg-de–Vries equation when the value of the viscous is small, interesting differences emerge as the magnitude of the value of viscous increases. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=Korteweg%E2%80%93de%20Vries%E2%80%93Burgers%20equation" title="Korteweg–de Vries–Burgers equation">Korteweg–de Vries–Burgers equation</a>, <a href="https://publications.waset.org/abstracts/search?q=soliton" title=" soliton"> soliton</a>, <a href="https://publications.waset.org/abstracts/search?q=transcritical%20flow" title=" transcritical flow"> transcritical flow</a>, <a href="https://publications.waset.org/abstracts/search?q=viscous%20flow" title=" viscous flow"> viscous flow</a> </p> <a href="https://publications.waset.org/abstracts/182925/generation-transcritical-flow-influenced-by-dissipation-over-a-hole" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/182925.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">51</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">8</span> Thermodynamics Analysis of Transcritical HTHP Cycles Using Eco-Friendly Refrigerant and low-Grade Waste Heat Recovery: A Theoretical Evaluation</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Adam%20Y.%20Sulaiman">Adam Y. Sulaiman</a>, <a href="https://publications.waset.org/abstracts/search?q=Donal%20F.%20Cotter"> Donal F. Cotter</a>, <a href="https://publications.waset.org/abstracts/search?q=Ming%20J.%20Huang"> Ming J. Huang</a>, <a href="https://publications.waset.org/abstracts/search?q=Neil%20J.%20Hewitt"> Neil J. Hewitt</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Decarbonization of the industrial sector in developed countries has become indispensable for addressing climate change. Industrial processes including drying, distillation, and injection molding require a process heat exceeding 180°C, rendering the subcriticalHigh-Temperature heat pump(HTHP) technique unsuitable. A transcritical HTHP utilizing ecologically friendly working fluids is a highly recommended system that incorporates the features of high-energy efficiency, extended operational range, and decarbonizing the industrial sector. This paper delves into the possibility and feasibility of leveraging the HTTP system to provide up to 200°C of heat using R1233zd(E) as a working fluid. Using a steady-state model, various transcritical HTHP cycle configurations aretheoretically compared,analyzed, and evaluatedin this study. The heat transfer characteristics for the evaporator and gas cooler are investigated, as well as the cycle's energy, exergetic, and environmental performance. Using the LMTD method, the gas cooler's heat transfer coefficient, overall length, and heat transfer area were calculated. The findings indicate that the heat sink pressure level, as well as the waste heat temperature provided to the evaporator, have a significant impact on overall cycle performance. The investigation revealed the potential challenges and barriers, including the length of the gas cooler and the lubrication of the compression process. The basic transcritical HTTP cycle with additional IHX was demonstrated to be the most efficient cycle across a variety of heat source temperatures ranging from 70 to 90 °C based on theoretical energetic and exergetic performance. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=high-temperature%20heat%20pump" title="high-temperature heat pump">high-temperature heat pump</a>, <a href="https://publications.waset.org/abstracts/search?q=transcritical%20cycle" title=" transcritical cycle"> transcritical cycle</a>, <a href="https://publications.waset.org/abstracts/search?q=refrigerants" title=" refrigerants"> refrigerants</a>, <a href="https://publications.waset.org/abstracts/search?q=gas%20cooler" title=" gas cooler"> gas cooler</a>, <a href="https://publications.waset.org/abstracts/search?q=energy" title=" energy"> energy</a>, <a href="https://publications.waset.org/abstracts/search?q=exergy" title=" exergy"> exergy</a> </p> <a href="https://publications.waset.org/abstracts/146603/thermodynamics-analysis-of-transcritical-hthp-cycles-using-eco-friendly-refrigerant-and-low-grade-waste-heat-recovery-a-theoretical-evaluation" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/146603.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">163</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">7</span> Analysis of a CO₂ Two-Phase Ejector Performances with Taguchi and Anova Optimization</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Karima%20Megdouli">Karima Megdouli</a> </p> <p class="card-text"><strong>Abstract:</strong></p> The ejector, a central element within the CO₂ transcritical ejection refrigeration system, holds significant importance in enhancing refrigeration capacity and minimizing compressor power usage. This study's objective is to introduce a technique for enhancing the effectiveness of the CO₂ transcritical two-phase ejector, utilizing Taguchi and ANOVA analysis. The investigation delves into the impact of geometric parameters, secondary flow temperature, and primary flow pressure on the efficiency of the ejector. Results indicate that employing a combination of Taguchi and ANOVA offers increased reliability and superior performance when optimizing the design of the CO₂ two-phase ejector. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=ejector" title="ejector">ejector</a>, <a href="https://publications.waset.org/abstracts/search?q=supersonic" title=" supersonic"> supersonic</a>, <a href="https://publications.waset.org/abstracts/search?q=Taguchi" title=" Taguchi"> Taguchi</a>, <a href="https://publications.waset.org/abstracts/search?q=ANOVA" title=" ANOVA"> ANOVA</a>, <a href="https://publications.waset.org/abstracts/search?q=optimization" title=" optimization"> optimization</a> </p> <a href="https://publications.waset.org/abstracts/173279/analysis-of-a-co2-two-phase-ejector-performances-with-taguchi-and-anova-optimization" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/173279.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">88</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">6</span> Experimental Study on the Heating Characteristics of Transcritical CO₂ Heat Pumps</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Lingxiao%20Yang">Lingxiao Yang</a>, <a href="https://publications.waset.org/abstracts/search?q=Xin%20Wang"> Xin Wang</a>, <a href="https://publications.waset.org/abstracts/search?q=Bo%20Xu"> Bo Xu</a>, <a href="https://publications.waset.org/abstracts/search?q=Zhenqian%20Chen"> Zhenqian Chen</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Due to its outstanding environmental performance, higher heating temperature and excellent low-temperature performance, transcritical carbon dioxide (CO₂) heat pumps are receiving more and more attention. However, improperly set operating parameters have a serious negative impact on the performance of the transcritical CO₂ heat pump due to the properties of CO₂. In this study, the heat transfer characteristics of the gas cooler are studied based on the modified “three-stage” gas cooler, then the effect of three operating parameters, compressor speed, gas cooler water-inlet flowrate and gas cooler water-inlet temperature, on the heating process of the system are investigated from the perspective of thermal quality and heat capacity. The results shows that: In the heat transfer process of gas cooler, the temperature distribution of CO₂ and water shows a typical “two region” and “three zone” pattern; The rise in the cooling pressure of CO₂ serves to increase the thermal quality on the CO₂ side of the gas cooler, which in turn improves the heating temperature of the system; Nevertheless, the elevated thermal quality on the CO₂ side can exacerbate the mismatch of heat capacity on both sides of the gas cooler, thereby adversely affecting the system coefficient of performance (COP); Furthermore, increasing compressor speed mitigates the mismatch in heat capacity caused by elevated thermal quality, which is exacerbated by decreasing gas cooler water-inlet flowrate and rising gas cooler water-inlet temperature; As a delegate, the varying compressor speed results in a 7.1°C increase in heating temperature within the experimental range, accompanied by a 10.01% decrease in COP and an 11.36% increase in heating capacity. This study can not only provide an important reference for the theoretical analysis and control strategy of the transcritical CO₂ heat pump, but also guide the related simulation and the design of the gas cooler. However, the range of experimental parameters in the current study is small and the conclusions drawn are not further analysed quantitatively. Therefore, expanding the range of parameters studied and proposing corresponding quantitative conclusions and indicators with universal applicability could greatly increase the practical applicability of this study. This is also the goal of our next research. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=transcritical%20CO%E2%82%82%20heat%20pump" title="transcritical CO₂ heat pump">transcritical CO₂ heat pump</a>, <a href="https://publications.waset.org/abstracts/search?q=gas%20cooler" title=" gas cooler"> gas cooler</a>, <a href="https://publications.waset.org/abstracts/search?q=heat%20capacity" title=" heat capacity"> heat capacity</a>, <a href="https://publications.waset.org/abstracts/search?q=thermal%20quality" title=" thermal quality"> thermal quality</a> </p> <a href="https://publications.waset.org/abstracts/191320/experimental-study-on-the-heating-characteristics-of-transcritical-co2-heat-pumps" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/191320.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">19</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">5</span> Cascaded Transcritical/Supercritical CO2 Cycles and Organic Rankine Cycles to Recover Low-Temperature Waste Heat and LNG Cold Energy Simultaneously</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Haoshui%20Yu">Haoshui Yu</a>, <a href="https://publications.waset.org/abstracts/search?q=Donghoi%20Kim"> Donghoi Kim</a>, <a href="https://publications.waset.org/abstracts/search?q=Truls%20Gundersen"> Truls Gundersen</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Low-temperature waste heat is abundant in the process industries, and large amounts of Liquefied Natural Gas (LNG) cold energy are discarded without being recovered properly in LNG terminals. Power generation is an effective way to utilize low-temperature waste heat and LNG cold energy simultaneously. Organic Rankine Cycles (ORCs) and CO<sub>2</sub> power cycles are promising technologies to convert low-temperature waste heat and LNG cold energy into electricity. If waste heat and LNG cold energy are utilized simultaneously in one system, the performance may outperform separate systems utilizing low-temperature waste heat and LNG cold energy, respectively. Low-temperature waste heat acts as the heat source and LNG regasification acts as the heat sink in the combined system. Due to the large temperature difference between the heat source and the heat sink, cascaded power cycle configurations are proposed in this paper. Cascaded power cycles can improve the energy efficiency of the system considerably. The cycle operating at a higher temperature to recover waste heat is called top cycle and the cycle operating at a lower temperature to utilize LNG cold energy is called bottom cycle in this study. The top cycle condensation heat is used as the heat source in the bottom cycle. The top cycle can be an ORC, transcritical CO<sub>2</sub> (tCO<sub>2</sub>) cycle or supercritical CO<sub>2</sub> (sCO<sub>2</sub>) cycle, while the bottom cycle only can be an ORC due to the low-temperature range of the bottom cycle. However, the thermodynamic path of the tCO<sub>2</sub> cycle and sCO<sub>2</sub> cycle are different from that of an ORC. The tCO<sub>2</sub> cycle and the sCO<sub>2</sub> cycle perform better than an ORC for sensible waste heat recovery due to a better temperature match with the waste heat source. Different combinations of the tCO<sub>2</sub> cycle, sCO<sub>2</sub> cycle and ORC are compared to screen the best configurations of the cascaded power cycles. The influence of the working fluid and the operating conditions are also investigated in this study. Each configuration is modeled and optimized in Aspen HYSYS. The results show that cascaded tCO<sub>2</sub>/ORC performs better compared with cascaded ORC/ORC and cascaded sCO<sub>2</sub>/ORC for the case study. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=LNG%20cold%20energy" title="LNG cold energy">LNG cold energy</a>, <a href="https://publications.waset.org/abstracts/search?q=low-temperature%20waste%20heat" title=" low-temperature waste heat"> low-temperature waste heat</a>, <a href="https://publications.waset.org/abstracts/search?q=organic%20Rankine%20cycle" title=" organic Rankine cycle"> organic Rankine cycle</a>, <a href="https://publications.waset.org/abstracts/search?q=supercritical%20CO%E2%82%82%20cycle" title=" supercritical CO₂ cycle"> supercritical CO₂ cycle</a>, <a href="https://publications.waset.org/abstracts/search?q=transcritical%20CO%E2%82%82%20cycle" title=" transcritical CO₂ cycle"> transcritical CO₂ cycle</a> </p> <a href="https://publications.waset.org/abstracts/86899/cascaded-transcriticalsupercritical-co2-cycles-and-organic-rankine-cycles-to-recover-low-temperature-waste-heat-and-lng-cold-energy-simultaneously" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/86899.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">260</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">4</span> Evaluation of Advanced Architectures for Commercial Refrigeration Systems Using Low Global Warming Potential Refrigerants</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Fabrizio%20Codella">Fabrizio Codella</a>, <a href="https://publications.waset.org/abstracts/search?q=Chris%20Parker"> Chris Parker</a>, <a href="https://publications.waset.org/abstracts/search?q=Samer%20Saab"> Samer Saab</a> </p> <p class="card-text"><strong>Abstract:</strong></p> The Kigali Amendment is driving the adoption of low Global Warming Potential refrigerants in commercial refrigeration systems in over a hundred countries. Several refrigeration systems for the small and large retail stores at mild and hot ambient temperature climates have been compared for hydrofluorocarbons (HFC), hydrofluoroolefins (HFO), transcritical CO₂ and propane, in typical and advanced system architectures. The results of system performance, emissions and lifetime cost have been compared. The greatest benefits were found to be obtained by low global warming potential HFO advanced systems. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=commercial%20refrigeration" title="commercial refrigeration">commercial refrigeration</a>, <a href="https://publications.waset.org/abstracts/search?q=CO%E2%82%82" title=" CO₂"> CO₂</a>, <a href="https://publications.waset.org/abstracts/search?q=emissions" title=" emissions"> emissions</a>, <a href="https://publications.waset.org/abstracts/search?q=HFO" title=" HFO"> HFO</a>, <a href="https://publications.waset.org/abstracts/search?q=lifetime%20cost" title=" lifetime cost"> lifetime cost</a>, <a href="https://publications.waset.org/abstracts/search?q=performance" title=" performance"> performance</a> </p> <a href="https://publications.waset.org/abstracts/148303/evaluation-of-advanced-architectures-for-commercial-refrigeration-systems-using-low-global-warming-potential-refrigerants" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/148303.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">153</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">3</span> Time Delayed Susceptible-Vaccinated-Infected-Recovered-Susceptible Epidemic Model along with Nonlinear Incidence and Nonlinear Treatment</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Kanica%20Goel">Kanica Goel</a>, <a href="https://publications.waset.org/abstracts/search?q=Nilam"> Nilam</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Infectious diseases are a leading cause of death worldwide and hence a great challenge for every nation. Thus, it becomes utmost essential to prevent and reduce the spread of infectious disease among humans. Mathematical models help to better understand the transmission dynamics and spread of infections. For this purpose, in the present article, we have proposed a nonlinear time-delayed SVIRS (Susceptible-Vaccinated-Infected-Recovered-Susceptible) mathematical model with nonlinear type incidence rate and nonlinear type treatment rate. Analytical study of the model shows that model exhibits two types of equilibrium points, namely, disease-free equilibrium and endemic equilibrium. Further, for the long-term behavior of the model, stability of the model is discussed with the help of basic reproduction number R₀ and we showed that disease-free equilibrium is locally asymptotically stable if the basic reproduction number R₀ is less than one and unstable if the basic reproduction number R₀ is greater than one for the time lag τ≥0. Furthermore, when basic reproduction number R₀ is one, using center manifold theory and Casillo-Chavez and Song theorem, we showed that the model undergoes transcritical bifurcation. Moreover, numerical simulations are being carried out using MATLAB 2012b to illustrate the theoretical results. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=nonlinear%20incidence%20rate" title="nonlinear incidence rate">nonlinear incidence rate</a>, <a href="https://publications.waset.org/abstracts/search?q=nonlinear%20treatment%20rate" title=" nonlinear treatment rate"> nonlinear treatment rate</a>, <a href="https://publications.waset.org/abstracts/search?q=stability" title=" stability"> stability</a>, <a href="https://publications.waset.org/abstracts/search?q=time%20delayed%20SVIRS%20epidemic%20model" title=" time delayed SVIRS epidemic model"> time delayed SVIRS epidemic model</a> </p> <a href="https://publications.waset.org/abstracts/91055/time-delayed-susceptible-vaccinated-infected-recovered-susceptible-epidemic-model-along-with-nonlinear-incidence-and-nonlinear-treatment" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/91055.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">149</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">2</span> A Qualitative Description of the Dynamics in the Interactions between Three Populations: Pollinators, Plants, and Herbivores</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Miriam%20Sosa-D%C3%ADaz">Miriam Sosa-Díaz</a>, <a href="https://publications.waset.org/abstracts/search?q=Faustino%20S%C3%A1nchez-Gardu%C3%B1o"> Faustino Sánchez-Garduño</a> </p> <p class="card-text"><strong>Abstract:</strong></p> In population dynamics the study of both, the abundance and the spatial distribution of the populations in a given habitat, is a fundamental issue a From ecological point of view, the determination of the factors influencing such changes involves important problems. In this paper a mathematical model to describe the temporal dynamic and the spatiotemporal dynamic of the interaction of three populations (pollinators, plants and herbivores) is presented. The study we present is carried out by stages: 1. The temporal dynamics and 2. The spatio-temporal dynamics. In turn, each of these stages is developed by considering three cases which correspond to the dynamics of each type of interaction. For instance, for stage 1, we consider three ODE nonlinear systems describing the pollinator-plant, plant-herbivore and plant-pollinator-herbivore, interactions, respectively. In each of these systems different types of dynamical behaviors are reported. Namely, transcritical and pitchfork bifurcations, existence of a limit cycle, existence of a heteroclinic orbit, etc. For the spatiotemporal dynamics of the two mathematical models a novel factor are introduced. This consists in considering that both, the pollinators and the herbivores, move towards those places of the habitat where the plant population density is high. In mathematical terms, this means that the diffusive part of the pollinators and herbivores equations depend on the plant population density. The analysis of this part is presented by considering pairs of populations, i. e., the pollinator-plant and plant-herbivore interactions and at the end the two mathematical model is presented, these models consist of two coupled nonlinear partial differential equations of reaction-diffusion type. These are defined on a rectangular domain with the homogeneous Neumann boundary conditions. We focused in the role played by the density dependent diffusion term into the coexistence of the populations. For both, the temporal and spatio-temporal dynamics, a several of numerical simulations are included. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=bifurcation" title="bifurcation">bifurcation</a>, <a href="https://publications.waset.org/abstracts/search?q=heteroclinic%20orbits" title=" heteroclinic orbits"> heteroclinic orbits</a>, <a href="https://publications.waset.org/abstracts/search?q=steady%20state" title=" steady state"> steady state</a>, <a href="https://publications.waset.org/abstracts/search?q=traveling%20wave" title=" traveling wave"> traveling wave</a> </p> <a href="https://publications.waset.org/abstracts/48776/a-qualitative-description-of-the-dynamics-in-the-interactions-between-three-populations-pollinators-plants-and-herbivores" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/48776.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">298</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">1</span> A Hybrid Artificial Intelligence and Two Dimensional Depth Averaged Numerical Model for Solving Shallow Water and Exner Equations Simultaneously</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=S.%20Mehrab%20Amiri">S. Mehrab Amiri</a>, <a href="https://publications.waset.org/abstracts/search?q=Nasser%20Talebbeydokhti"> Nasser Talebbeydokhti</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Modeling sediment transport processes by means of numerical approach often poses severe challenges. In this way, a number of techniques have been suggested to solve flow and sediment equations in decoupled, semi-coupled or fully coupled forms. Furthermore, in order to capture flow discontinuities, a number of techniques, like artificial viscosity and shock fitting, have been proposed for solving these equations which are mostly required careful calibration processes. In this research, a numerical scheme for solving shallow water and Exner equations in fully coupled form is presented. First-Order Centered scheme is applied for producing required numerical fluxes and the reconstruction process is carried out toward using Monotonic Upstream Scheme for Conservation Laws to achieve a high order scheme.  In order to satisfy C-property of the scheme in presence of bed topography, Surface Gradient Method is proposed. Combining the presented scheme with fourth order Runge-Kutta algorithm for time integration yields a competent numerical scheme. In addition, to handle non-prismatic channels problems, Cartesian Cut Cell Method is employed. A trained Multi-Layer Perceptron Artificial Neural Network which is of Feed Forward Back Propagation (FFBP) type estimates sediment flow discharge in the model rather than usual empirical formulas. Hydrodynamic part of the model is tested for showing its capability in simulation of flow discontinuities, transcritical flows, wetting/drying conditions and non-prismatic channel flows. In this end, dam-break flow onto a locally non-prismatic converging-diverging channel with initially dry bed conditions is modeled. The morphodynamic part of the model is verified simulating dam break on a dry movable bed and bed level variations in an alluvial junction. The results show that the model is capable in capturing the flow discontinuities, solving wetting/drying problems even in non-prismatic channels and presenting proper results for movable bed situations. It can also be deducted that applying Artificial Neural Network, instead of common empirical formulas for estimating sediment flow discharge, leads to more accurate results. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=artificial%20neural%20network" title="artificial neural network">artificial neural network</a>, <a href="https://publications.waset.org/abstracts/search?q=morphodynamic%20model" title=" morphodynamic model"> morphodynamic model</a>, <a href="https://publications.waset.org/abstracts/search?q=sediment%20continuity%20equation" title=" sediment continuity equation"> sediment continuity equation</a>, <a href="https://publications.waset.org/abstracts/search?q=shallow%20water%20equations" title=" shallow water equations"> shallow water equations</a> </p> <a href="https://publications.waset.org/abstracts/90261/a-hybrid-artificial-intelligence-and-two-dimensional-depth-averaged-numerical-model-for-solving-shallow-water-and-exner-equations-simultaneously" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/90261.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">187</span> </span> </div> </div> </div> </main> <footer> <div id="infolinks" class="pt-3 pb-2"> <div class="container"> <div style="background-color:#f5f5f5;" class="p-3"> <div class="row"> <div class="col-md-2"> <ul class="list-unstyled"> About <li><a href="https://waset.org/page/support">About Us</a></li> <li><a href="https://waset.org/page/support#legal-information">Legal</a></li> <li><a target="_blank" rel="nofollow" href="https://publications.waset.org/static/files/WASET-16th-foundational-anniversary.pdf">WASET celebrates 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