建模与仿真(英文)最新文献

{"title":"Numerical Analysis of a Sliding frictional contact problem with Normal Compliance and Unilateral Contact","authors":"Yahyeh Souleiman, M. Barboteu","doi":"10.21203/rs.3.rs-29447/v1","DOIUrl":"https://doi.org/10.21203/rs.3.rs-29447/v1","url":null,"abstract":"\u0000 This paper represents a continuation of [15] and [18]. Here, we consider the numerical analysis of a non trivial frictional contact problen in a form of a system of evolution nonlinear partial differential equations. The model describes the equilibrium of a viscoelastic body in sliding contact with a moving foundation. The contact is modeled with a multivalued normal compliance condition with memory term restricted by a unilateral constraint, and is associated to a sliding version of Coulomb's law of dry friction. After a description of the model and some assumptions, we derive a variational formulation of the problem, which consists of a system coupling a variational inequality for the displacement field and a nonlinear equation for the stress field. Then, we introduce a fully discrete scheme for the numerical approximation of the sliding contact problem. Under certain solution regularity assumptions, we derive an optimal order error estimate and we provide numerical validation of this result by considering some numerical simulations in the study of a two-dimensional problem.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46907402","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":"Hydrodynamic Model for Operational Forecasting in Coastal Waters of Ghana","authors":"F. Uba, E. O. Essandoh, E. Nyantakyi, Prosper Anumah","doi":"10.4236/ojmsi.2020.82004","DOIUrl":"https://doi.org/10.4236/ojmsi.2020.82004","url":null,"abstract":"The provision of economic resources to countries at the shore of Gulf of Guinea is a very important effort that \u0000has helped West Africa to develop to some extent. Taking the study area as a \u0000system it will be important to know the dynamics that occur in it to help neighouring countries predict its physical and \u0000thermodynamics states at all times. Ghana is located in West Africa and it is \u0000bordered in the south by the Gulf of Guinea or Atlantic Ocean. The objective of this research is to characterize the hydrodynamic \u0000circulation of the Gulf of Guinea areas neighouring Ghana. A 3-Dimensional hydrodynamic model was implemented in the territorial \u0000waters of Ghana using the Modelo \u0000Hidrodinamico, MOHID model to represent the dynamics and study the \u0000complex circulation pattern of the sea. To achieve this in an affordable \u0000computational time, nested domain \u0000approach was used to implement the hydrodynamic model in both 2 and \u00003-Dimensional gridded levels. The first level is a barotropic model with only tide. The nested domains of the rest of \u0000the levels are baroclinic forced with atmospheric and oceanic elements. To \u0000quantify its accuracy, the model was validated and calibrated in three stages; first, the frequency of the water level, \u0000followed by the circulation pattern and last, analysing the nature and profiles of the atmospheric and oceanic elements. The \u0000implemented model showed good agreement with the measured water surface level \u0000in the domain with mean error values not exceeding 14.00% of the measured data \u0000and with correlation factors higher than 0.80. Also, the intensity and \u0000direction of velocity observed in the current data are well represented by the \u0000model at the water surface levels with mean errors lower than 20.00% of the \u0000measured data components. The profiles obtained for both the temperature and \u0000salinity at shore show completely a straight line for salinity and also a \u0000straight line which is slightly curved at the top for the temperature profile. \u0000The vertical straight line for the salinity profile shows that at the shore the \u0000waters are not stratified vertically or they are well mixed. The slight curve \u0000at the top of the temperature graph accounts for the mixing dynamics that occur \u0000close to land or the effect of heat flux at the surface. It can be concluded \u0000that the hydrodynamic model obtained by this study is the true reflection of \u0000the territorial waters of Ghana.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47885307","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":"Modeling of Adhesive Particles Using a Combination of the Two-Body Interaction and Phase-Field Methods","authors":"T. Uehara","doi":"10.4236/ojmsi.2020.82003","DOIUrl":"https://doi.org/10.4236/ojmsi.2020.82003","url":null,"abstract":"Discrete materials such as powders and granular \u0000materials have been widely \u0000used due to their specific characteristics. The precise evaluation is \u0000accordingly becoming important, and various numerical schemes have been \u0000developed. However, the interactions among the constituent particles are still \u0000difficult to model precisely. Especially, contact conditions, which vary with \u0000material properties and circumstances, are difficult to formulate. In this \u0000study, a computational \u0000model for simulating adhesive particles on contact in a many-particle system is proposed. \u0000The interaction between the particles was represented by a two-body repulsive force that depends on the \u0000distance between particles and an additional adhesive force at the contact \u0000point. A phase-field variable was introduced to express the surface of each \u0000particle, and the adhesive force was formulated using the phase-field \u0000distribution. As a result, the adhesion of particles was properly expressed. For a \u0000mono-particle system, neighboring particles adhered and uniformly aggregated, \u0000while for a dual-particle system, several characteristic patterns were obtained \u0000depending on the initial arrangement of the particles. Repulsive contact was \u0000also considered as a specific case, and the corresponding results were obtained.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70368308","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 Study of Microchannel Plate Gain Using SIMION","authors":"Yifan Zhao","doi":"10.4236/ojmsi.2020.81001","DOIUrl":"https://doi.org/10.4236/ojmsi.2020.81001","url":null,"abstract":"Microchannel plates (MCP) are widely used for particle detection. The gain of chevron MCPs is related to geometrical parameters, but no study has been done through SIMION simulation. The purpose of this study is to model a chevron MCP and its secondary emission process using SIMION and determine the relationship between microchannel plate gain, voltage, channel bias angle, and diameter. Two geometry files simulated MCP electric field and shape, and a Lua program simulated secondary emission. Simulation results showed that MCP gain is proportional to voltage, angles between 5 and 15 degrees maximize gain, and gain is inversely proportional to the diameter. This study accurately simulates a chevron MCP and yields the relationship between gain, voltage, channel bias angle, and diameter. Further studies are needed to simulate electron trajectories for improved precision.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44683385","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":"Markov Chain Monte Carlo Solution of Laplace’s Equation in Axisymmetric Homogeneous Domain","authors":"Adebowale E. Shadare, M. Sadiku, S. Musa","doi":"10.4236/ojmsi.2019.74012","DOIUrl":"https://doi.org/10.4236/ojmsi.2019.74012","url":null,"abstract":"With increasing complexity of today’s electromagnetic problems, the need and opportunity to reduce domain sizes, memory requirement, computational time and possibility of errors abound for symmetric domains. With several competing computational methods in recent times, methods with little or no iterations are generally preferred as they tend to consume less computer memory resources and time. This paper presents the application of simple and efficient Markov Chain Monte Carlo (MCMC) method to the Laplace’s equation in axisymmetric homogeneous domains. Two cases of axisymmetric homogeneous problems are considered. Simulation results for analytical, finite difference and MCMC solutions are reported. The results obtained from the MCMC method agree with analytical and finite difference solutions. However, the MCMC method has the advantage that its implementation is simple and fast.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43248352","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":"Global-Local Finite Element Analysis for Predicting Separation in Cord-Rubber Composites of Radial Truck Tires","authors":"K. Jeong, Kee-Woon Kim, J. Kim","doi":"10.4236/ojmsi.2019.74011","DOIUrl":"https://doi.org/10.4236/ojmsi.2019.74011","url":null,"abstract":"A global-local finite element modeling technique is employed in this paper to predict the separation in steel cord-rubber composite materials of radial truck tires. The local model uses a finite element analysis in conjunction with a glob-al-local technique in ABAQUS. A 3-dimensional finite element local model calculates the maximum cyclic shear strain of an interface between steel cord and rubber materials at the carcass ply shoulder region. It is found that the maximum cyclic shear strain is reliable as a result of the analysis of carcass ply separation in radial truck tires. Using the analysis of the local model, a study of the cyclic shear strain is performed in the shoulder region and used to deter-mine the carcass ply separation. The effect of the change of carcass ply design on the separation in steel cord-rubber composite materials of radial truck tires is discussed.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46633858","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":"Survival Analysis of Factor Affects Survival Time of Hypertension Patients","authors":"Abtsega Samuel Ayalew, Markos Abiso Erango, K. Gergiso","doi":"10.4236/ojmsi.2019.74010","DOIUrl":"https://doi.org/10.4236/ojmsi.2019.74010","url":null,"abstract":"Hypertension is a major long-term health condition and a leading modifiable risk factor for cardiovascular disease and death. The aim of this study was to examine major factors that affect survival time of hypertension patients under follow-up. We considered a total of 430 random samples of hypertension patients who had been under follow up at Yekatit-12 Hospital in Ethiopia from January 2013 to January 2019. Four parametric accelerated failure time distributions: Exponential, Weibull, Lognormal and loglogistic are used to analyse survival probabilities of the patients. The Kaplan-Meierestimation method and log-rank tests were used to compare the survival experience of patients with respect to different covariates. The Weibull model is selected to best fit to the data sets. The results indicate that the baseline age of the patient, place of residence, family history of hypertension, khat intake, blood cholesterol level of the patient, hypertension disease stage, adherence to the treatment and related disease were significantly associated with survival time of hypertension patients. But factor like gender, tobacco use, alcohol use, diabetes mellitus status and fasting blood sugar were not significantly associated factors. Society and all stakeholders should be aware of the consequences of these factors which can influence the survival time of hypertension patients.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41818837","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":"Optimal Threshold Determination for the Maximum Product of Spacing Methodology with Ties for Extreme Events","authors":"P. Murage, J. Mung'atu, E. Odero","doi":"10.4236/OJMSI.2019.73008","DOIUrl":"https://doi.org/10.4236/OJMSI.2019.73008","url":null,"abstract":"Extreme events are defined as values of the event below or above a certain value called threshold. A well chosen threshold helps to identify the extreme levels. Several methods have been used to determine threshold so as to analyze and model extreme events. One of the most successful methods is the maximum product of spacing (MPS). However, there is a problem encountered while modeling data through this method in that the method breaks down when there is a tie in the exceedances. This study offers a solution to model data even if it contains ties. To do so, an optimal threshold that gives more optimal parameters for extreme events, was determined. The study achieved its main objective by deriving a method that improved MPS method for determining an optimal threshold for extreme values in a data set containing ties, estimated the Generalized Pareto Distribution (GPD) parameters for the optimal threshold derived and compared these GPD parameters with GPD parameters determined through the standard MPS model. The study improved maximum product of spacing method and used Generalized Pareto Distribution (GPD) and Peak over threshold (POT) methods as the basis of identifying extreme values. This study will help the statisticians in different sectors of our economy to model extreme events involving ties. To statisticians, the structure of the extreme levels which exist in the tails of the ordinary distributions is very important in analyzing, predicting and forecasting the likelihood of an occurrence of the extreme event.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44953270","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":"Analysis of the Effect of Supplying Vessel on Wave Drift Force of Semi-Submersible Platform","authors":"Chi Zhang, Baojie Zhang","doi":"10.4236/OJMSI.2019.73009","DOIUrl":"https://doi.org/10.4236/OJMSI.2019.73009","url":null,"abstract":"Wave drift force is the key factor affecting the mooring ability of semi-submersible platform. Aiming at the mooring system composed of replenishment ship and semi-submersible platform, the influence of hydrodynamic interference on semi-submersible platform is analyzed. Based on the three-dimensional potential flow theory and AQWA software, the effects of different wave directions and spacing on the wave drift force of semi-submersible platform are considered. The results show that the hydrodynamic interference of the replenishment ship will affect the wave drift force of the semi-submersible platform, and the influence of the distance between adjacent vessels and the wave direction angle is more sensitive in the middle and high wave frequencies. This paper can provide support for the research of hydrodynamic interference of semi-submersible platform.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45562410","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":"Simulating the Health Impact of Particulate Emissions from Transport Fuels Using Multipath Particle Deposition Model (MPPD)","authors":"Bornes C. Mosonik, J. Kibet, S. Ngari","doi":"10.4236/OJMSI.2019.72006","DOIUrl":"https://doi.org/10.4236/OJMSI.2019.72006","url":null,"abstract":"Transport fuels emit particulates of varying chemical nature and size. These particulates are known to cause respiratory problems of medical concern. The need to simulate the breathing characteristics of particulates generated from combustion events is very important in estimating the respiratory clearance of these particles. Consequently, this study examines the nature of particulate matter from the pyrolysis of a mixture Croton megalocarpus biodiesel and fossil diesel, and pure biodiesel. The study was explored at an optimum temperature of 600°C in an inert nitrogen environment at a contact time of 2 sec. Scanning electron microscope was used to examine the surface of the particulates. Multiple-Path Particulate Dosage (MPPD Ver. 3.04) model was used to determine the breathing phenomena of infants, teenagers and adults at different orientations. Co-pyrolytic Char particulates and pyrolytic croton thermal char were classified as ultrafine, PM0.03 and PM0.02 respectively. The MPPD model results indicated that ultrafine particles tend to be deposited in pulmonary regions more than head and trachea regions, due to high probability of diffusibiliy of ultrafine particles. It was noted that 8 years old exhibits a unique trend with high total deposition and poor respiratory clearance when compared to an adult of 21 years old.","PeriodicalId":56990,"journal":{"name":"建模与仿真(英文)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42401522","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}