建模与仿真(英文)最新文献

{"title":"Single parameter model for cosmic scale photon redshift in a closed Universe","authors":"A. Steynberg","doi":"10.21203/rs.3.rs-180626/v1","DOIUrl":"https://doi.org/10.21203/rs.3.rs-180626/v1","url":null,"abstract":"\u0000 A successful single parameter model has been formulated to match the observations of photons from type 1a supernovae which were previously used to corroborate the standard 𝛬 cold dark matter model. The new single parameter model extrapolates all the way back to the cosmic background radiation (CMB) without requiring a separate model to describe inflation of the space dimensions after the Big Bang. The model for the redshift progression of a photon is: 1 + z =(frac{text{sin}left(frac{13.8}{T}right)pi /2}{text{sin}left(frac{t}{T}right)pi /2}) T is the fitted parameter and t is the time when the photon was emitted, both measured in billions of years from time zero in the Big Bang. The angle is expressed in radians. The number 13.8 should be updated if an improved estimate for the time elapsed since the Big Bang is found. The single parameter model assumes that spacetime forms a finite symmetrical manifold with positive curvature.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48091243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Marshall-Olkin Right Truncated Fr&eacutechet-Inverted Weibull Distribution: Its Properties and Applications","authors":"Nora Nader, M. El-Damcese, B. El-Desouky","doi":"10.4236/OJMSI.2021.91005","DOIUrl":"https://doi.org/10.4236/OJMSI.2021.91005","url":null,"abstract":"In this paper, a new probability distribution is \u0000proposed by using Marshall and Olkin transformation. Some of its properties \u0000such as moments, moment generating function, order statistics and reliability \u0000functions are derived. The method of maximum \u0000likelihood is used to estimate the model parameters. The graphs of the \u0000reliability function and hazard rate function are plotted by taken some values \u0000of the parameters. Three real life applications are introduced to compare the \u0000behaviour of the new distribution with other distributions.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46496576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Applying Graph Theory and Mathematical-Computational Modelling to Study a Neurophysiological Circuit","authors":"Camila de Andrade Kalil, M. C. Castro, Dilson Silva, C. Cortez","doi":"10.4236/OJMSI.2021.92011","DOIUrl":"https://doi.org/10.4236/OJMSI.2021.92011","url":null,"abstract":"The aim of the present study is to contribute to the knowledge about the functioning of the neuronal circuits. We built a mathematical-computational model using graph theory for a complex neurophysiological circuit consisting of a reverberating neuronal circuit and a parallel neuronal circuit, which could be coupled. Implementing our model in C++ and applying neurophysiological values found in the literature, we studied the discharge pattern of the reverberant circuit and the parallel circuit separately for the same input signal pattern, examining the influence of the refractory period and the synaptic delay on the respective output signal patterns. Then, the same study was performed for the complete circuit, in which the two circuits were coupled, and the parallel circuit could then influence the functioning of the reverberant. The results showed that the refractory period played an important role in forming the pattern of the output spectrum of a reverberating circuit. The inhibitory action of the parallel circuit was able to regulate the reverberation frequency, suggesting that parallel circuits may be involved in the control of reverberation circuits related to motive activities underlying precision tasks and perhaps underlying neural work processes and immediate memories.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70368362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Finite Element Model of Unsteady Cavitating Fluid Flow around a Hydrofoil","authors":"C. Carbonel","doi":"10.4236/ojmsi.2021.94027","DOIUrl":"https://doi.org/10.4236/ojmsi.2021.94027","url":null,"abstract":"The present study deals with the unsteady dynamics of cavitation around the NACA 0015 hydrofoil in a channel. A finite element model is proposed to solve the governing equations of momentum and mass conservation. Turbulent flows around the hydrofoil are described by the Prandtl-Kolmogorov model. The cavitation phenomenon is modeled through a mixture model in-volving liquid and vapor flows and the Zwart-Gerber-Belamri (ZGB) model is considered to evaluate the transport of the water vapor fraction. The variational finite element model formulation includes the mixing of the characteristic method and the finite element. Also, at the open sides of the channel flow, an open boundary condition is imposed. Numerical experiments are performed for cavitation numbers 0.8 and 0.4. The presented model predicts the essential features of unsteady cavitating flows, the generation of vapor cavities, the time-dependent oscillations of the variables and the presence of vortical flow structures associated to vapor volume concentrations during the shedding process.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70368064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling and Simulation of an Ohmic Heating Process","authors":"Hongwei Zhang, A. Mohamed, T. Breikin, M. Howarth","doi":"10.4236/ojmsi.2021.91002","DOIUrl":"https://doi.org/10.4236/ojmsi.2021.91002","url":null,"abstract":"Ohmic Heating (OH) is one of the emerging thermal technologies used in food processing which can produce rapid and uniform heating with close to 100% energy transfer efficiency. Although mathematical modelling for OH processes has been studied by many researchers in recent years, systematic simulations of OH have not been developed for model-based control of the processes. In this paper, mathematical model for a Colinear Ohmic Heater is presented, analyzed, and studied based on the selected configuration. A numerical solution for the mathematical equations has been defined and proposed. MATLAB/Simulink model is hence developed and validated against the available data. Simulation results have shown that MATLAB/Simulink model can produce robust outputs at low computational costs with an accuracy of up to 99.6% in comparison to the analytical solution. This model can be used in further studies for analysis of the OH processes and development of advanced controllers.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70368318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Analysis of Thermal Convection in a CPU Chassis","authors":"M. Bangalee, M. M. Rahman, M. Ferdows, M. S. Islam","doi":"10.4236/OJMSI.2021.91003","DOIUrl":"https://doi.org/10.4236/OJMSI.2021.91003","url":null,"abstract":"Flow distribution and the effects of different boundary conditions are achieved for a steady-state conjugate (Conduction & Convection) heat transfer process. A plate fin heat sink with horizontal fin orientation along with a computer chassis is numerically investigated and simulated using software ANSYS CFX. Fin orientation of a heat sink changes the direction of fluid flow inside the chassis. For predicting turbulence of the flow inside the domain, a two-equation based k-e turbulence model is chosen. The Reynolds number based on inflow velocity and geometry is found 4.2 × 103 that indicates that the flow is turbulent inside the chassis. To get proper thermal cooling, the optimum velocity ratio of inlet/outlet, dimension of inlet/outlet and different positions of outlet on the back sidewall of the chassis are predicted. Aspect velocity ratio between the inlet airflow and the outlet airflow has an effect on the steadiness of the flow. Mass flow rate depends on the dimension of the inlet/outlet. The horizontal fin orientation with 1:1.6 inlet-outlet airflow velocity ratio gives better thermal performance when outlet is located at the top corner of the chassis, near to the inner sidewall. Flow distribution and heat transfer characteristics are also analyzed to obtain the final model.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70368352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Delayed Dynamics of SIR Model for COVID-19","authors":"H. Ebraheem, Nizar J. Alkhateeb, H. Badran, A. Hajjiah, Ebraheem Sultan","doi":"10.21203/rs.3.rs-101284/v1","DOIUrl":"https://doi.org/10.21203/rs.3.rs-101284/v1","url":null,"abstract":"\u0000 BackgroundThe global spread of the COVID-19 pandemic has been one of the most challenging tasks the world has faced since the last pandemic outbreak of 1918. Early on countries felt the strength and persistence of the virus infections spreading with no means of estimating the dispersion rates. Officials in infected countries followed several guidelines set by the World Health Organization (WHO) to try and flatten the infection curve and maintain a low number of infectives. Nonetheless, the virus kept on spreading with impunity and all predictions of how containments or peak detections have been a fail so far. Therefore, a need for a more accurate model to predict the peaking of infections and help guide officials on what best to enact as a measure of public health safety from a multitude of choices outlined by the WHO. Earlier studies of compartmental model of Susceptible-Infected-Recovered (SIR) did not predict the peaking of a hot spots flairs of viral infections and a new model needed to provide a more realistic results to serve public officials battling the pandemic worldwideMethodsA new modified SIR model which incorporates appropriate delay parameters leading to a more precise prediction of COVID-19 real time data. The predictions of the new model are compared to real data obtained from four countries, namely Germany, Italy, Kuwait, and Oman. Two included delay periods for incubation and recovery within the SIR model produces a sensible and more accurate representation of the real time data. The reproductive number 𝑅0 is defined for the model for values of recovery time delay 𝜏2 of the infective case.ResultsIncorporating two delay periods that corresponds to the duration of the incubational and recovery periods measured for COVID-19 gives a more accurate prediction of the peak pandemic infections per geographical area. The parameter variations in the model 𝛽,𝛾,𝛼,𝜏1,𝑎𝑛𝑑 𝜏2 makeup different cases corresponding to different situations. The variations are estimated a priori based on what is being observed and collected data of an infected region to give officials better guidelines on what health policies should be enacted in the future.2 of 15ConclusionsThe empirical data provided by WHO show that the proposed new SIR model gives a better more accurate prediction of COVID-19 pandemic spreading curve. The model is shown to closely fit real time data for four countries. Simulation results are consistent with data and generated curves are well constrained. The parameters can be varied and adjusted for producing and/or reproduction of numbers within the range of each country","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45681345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bertalanffy-Pütter Models for the Growth of Tropical Trees and Stands","authors":"N. Brunner, M. Kühleitner","doi":"10.4236/ojmsi.2020.84006","DOIUrl":"https://doi.org/10.4236/ojmsi.2020.84006","url":null,"abstract":"The \u0000Bertalanffy-Putter (BP) five-parameter growth model provides a versatile \u0000framework for the modeling of growth. Using data from a growth experiment in \u0000literature about the average size-at-age of 24 species of tropical trees over \u0000ten years in the same area, we identified their best-fit BP-model parameters. \u0000While different species had different best-fit exponent-pairs, there was a \u0000model with a good fit to 21 (87.5%) of the data (“Good fit” means a normalized \u0000root-mean-squared-error NRMSE \u0000below 2.5%. This threshold was the 95% quantile of the lognormal distribution \u0000that was fitted to the NRMSE \u0000values for the best-fit models for the data). In view of the sigmoidal character of this model \u0000despite the early stand we discuss whether the setting of the growth experiment may have \u0000impeded growth.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48865457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Demand and Capacity Modelling in Healthcare Using Discrete Event Simulation","authors":"Saurav Singla","doi":"10.4236/ojmsi.2020.84007","DOIUrl":"https://doi.org/10.4236/ojmsi.2020.84007","url":null,"abstract":"The NHS is right now confronting huge pressures \u0000relating to demand and capacity in radiology. The purpose of this research has \u0000been to provide information about MRI usage, details of operational aspects of \u0000MRI services, and to ascertain the planning intentions of NHS radiology \u0000services to keep up and create MRI capacity. The report expands on using \u0000Discrete Event Simulation (DES) to inspect and plan the utilisation of NHS \u0000hospital resources for the radiology department to help a 24 hr service that is \u0000available to outpatients which will help with diminishing patient waiting time, \u0000better resource usage, understanding the capacity and demand. Consequently, \u0000this research examines to adjust staff and resources with the demand of the \u0000MRI. The research was investigated using DES in various scenarios to find which \u0000resources are inactive; patients are treated slowly. DES helped in discovering \u0000resource utilisation and outpatient throughout the system. It additionally \u0000helped in distinguishing the bottlenecks in patient flow. The DES simulation \u0000results demonstrated that time for the outpatient in the system is less and \u0000more outpatients have been treated too. There is a higher level of outpatient \u0000patients leaving the system under 120 minutes. The report uncovered an MRI \u0000report interpretation time. Reception room time and MRI waiting room time are decreased \u0000significantly. It additionally exhibited with an expanded outflow of \u0000outpatients, resources, for example, MRI capacity and radiographer utilisation \u0000expanded.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41974696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Generalized Central Factorial Numbers with Odd Arguments","authors":"Youmna H. Zaid, F. Shiha, B. El-Desouky","doi":"10.4236/ojmsi.2020.83005","DOIUrl":"https://doi.org/10.4236/ojmsi.2020.83005","url":null,"abstract":"In this \u0000paper, we consider r-generalization of \u0000the central factorial numbers with odd arguments of the first and second kind. Mainly, \u0000we obtain various identities and properties related to these numbers. Matrix representation \u0000and the relation between these numbers and Pascal matrix are given. Furthermore, \u0000the distributions of the signless r-central factorial numbers are derived. In addition, \u0000connections between these numbers and the Legendre-Stirling numbers are given.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49250032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}