The fuzzy variable fractional differential equations(FVFDEs)play a very important role in mathematical modeling of COVID-19.The scientists are studying and developing several aspects of these COVID-19 models.The exist...The fuzzy variable fractional differential equations(FVFDEs)play a very important role in mathematical modeling of COVID-19.The scientists are studying and developing several aspects of these COVID-19 models.The existence and uniqueness of the solution,stability analysis are the most common and important study aspects.There is no study in the literature to establish the existence,uniqueness,and UH stability for fuzzy variable fractional(FVF)order COVID-19 models.Due to high demand of this study,we investigate results for the existence,uniqueness,and UH stability for the considered COVID-19 model based on FVFDEs using a fixed point theory approach with the singular operator.Additionally,discuss the maximal/minimal solution for the FVFDE of the COVID-19 model.展开更多
In this paper,time-fractional Sharma-Tasso-Olver(STO)equation has been solved numerically through the Petrov-Galerkin approach utilizing a quintic B-spline function as the test function and a linear hat function as th...In this paper,time-fractional Sharma-Tasso-Olver(STO)equation has been solved numerically through the Petrov-Galerkin approach utilizing a quintic B-spline function as the test function and a linear hat function as the trial function.The Petrov-Galerkin technique is effectively implemented to the fractional STO equation for acquiring the approximate solution numerically.The numerical outcomes are observed in adequate compatibility with those obtained from variational iteration method(VIM)and exact solutions.For fractional order,the numerical outcomes of fractional Sharma-Tasso-Olver equations are also compared with those obtained by variational iteration method(VIM)in Song et al.[Song L.,Wang Q.,Zhang H.,Rational approximation solution of the fractional Sharma-Tasso-Olver equation,J.Comput.Appl.Math.224:210-218,2009].Numerical experiments exhibit the accuracy and efficiency of the approach in order to solve nonlinear fractional STO equation.展开更多
The major goal of this paper is to isolate tumor region from nontumor regions and the estimation of tumor volume.Accurate segmentation is not an easy task due to the varying size,shape and location of the tumor.After ...The major goal of this paper is to isolate tumor region from nontumor regions and the estimation of tumor volume.Accurate segmentation is not an easy task due to the varying size,shape and location of the tumor.After segmentation,volume estimation is necessary in order to accurately estimate the tumor volume.By exactly estimating the volume of abnormal tissue,physicians can do excellent prognosis,clinical planning and dosage estimation.This paper describes a new Euclidean Similarity factor(ESF)based active contour model with deep learning for segmenting the tumor region into complete,core and enhanced tumor portions.Initially,the ESF considers the spatial distances and intensity differences of the region automatically to detect the tumor region.It preserves the image details but removes the noisy details.Then,the 3D Convolutional Neural Network(3D CNN)segments the tumor by automatically extracting spatiotemporal features.Finally,the extended shoelace method estimates the volume of the tumor accurately for n-sided polygons.The simulation result achieves a high accuracy of 92%and Jaccard index of 0.912 and computes the tumor volume with effective performance than existing approaches.展开更多
The main objective of this work is to check the compatibility of Finite element method(FEM)to determine the modal parameters of the rotor system and to compare the results with analytical method.Current work is an att...The main objective of this work is to check the compatibility of Finite element method(FEM)to determine the modal parameters of the rotor system and to compare the results with analytical method.Current work is an attempt to implement different finite element(FE)models for the estimation of modal parameters.Two different order elements from Beam,Axisymmetric and Solid FE models are considered.The analysis is carried out on the rotor system and the accuracy of the results and the computation time of the FE models are estimated.The FE results are compared with the analytical method.It is observed that FE model can be used to simulate even at higher order frequencies,which is a limitation of analytical model.The analysis shows that the FE results closely match with analytical method and also the study summarizes that proper choosing of FE helps in developing rotor models in both a desirable accuracy and efficiency.Finally,a Campbell diagram is generated using the analytical method and FEM.The critical speeds are also calculated from the Campbell diagram.The closeness of the results between the two methods is checked.展开更多
We demonstrate a new nonuniform mesh finite difference method to obtain accurate solutions for the elliptic partial differential equations in two dimensions with nonlinear first-order partial derivative terms.The meth...We demonstrate a new nonuniform mesh finite difference method to obtain accurate solutions for the elliptic partial differential equations in two dimensions with nonlinear first-order partial derivative terms.The method will be based on a geometric grid network area and included among the most stable differencing scheme in which the nine-point spatial finite differences are implemented,thus arriving at a compact formulation.In general,a third order of accuracy has been achieved and a fourth-order truncation error in the solution values will follow as a particular case.The efficiency of using geometric mesh ratio parameter has been shown with the help of illustrations.The convergence of the scheme has been established using the matrix analysis,and irreducibility is proved with the help of strongly connected characteristics of the iteration matrix.The difference scheme has been applied to test convection diffusion equation,steady state Burger’s equation,ocean model and a semi-linear elliptic equation.The computational results confirm the theoretical order and accuracy of the method.展开更多
In this paper,we studied a two-parameter transmuted model of Log-logistic distribution(LLD)using the quadratic rank transmutation map technique studied by Shaw and Buckley1 as a new survival model in medical sciences ...In this paper,we studied a two-parameter transmuted model of Log-logistic distribution(LLD)using the quadratic rank transmutation map technique studied by Shaw and Buckley1 as a new survival model in medical sciences and other applied fields.Statistical properties of Transmuted LLD(TLLD)are discussed comprehensively.Robust measures of skewness and kurtosis of the proposed model have also been discussed along with graphical overview.The estimation of the model parameters is performed by Maximum Likelihood(ML)method followed by a Monte Carlo(MC)simulation procedure to investigate the performance of the ML estimators and the asymptotic confidence intervals of the parameters.Applications of the proposed model to real-life data are also presented.展开更多
Personalization is the adaptation of the services to fit the user’s interests,characteristics and needs.The key to effective personalization is user profiling.Apart from traditional collaborative and content-based ap...Personalization is the adaptation of the services to fit the user’s interests,characteristics and needs.The key to effective personalization is user profiling.Apart from traditional collaborative and content-based approaches,a number of classification and clustering algorithms have been used to classify user related information to create user profiles.However,they are not able to achieve accurate user profiles.In this paper,we present a new clustering algorithm,namely Multi-Dimensional Clustering(MDC),to determine user profiling.The MDC is a version of the Instance-Based Learner(IBL)algorithm that assigns weights to feature values and considers these weights for the clustering.Three feature weight methods are proposed for the MDC and,all three,have been tested and evaluated.Simulations were conducted with using two sets of user profile datasets,which are the training(includes 10,000 instances)and test(includes 1000 instances)datasets.These datasets reflect each user’s personal information,preferences and interests.Additional simulations and comparisons with existing weighted and non-weighted instance-based algorithms were carried out in order to demonstrate the performance of proposed algorithm.Experimental results using the user profile datasets demonstrate that the proposed algorithm has better clustering accuracy performance compared to other algorithms.This work is based on the doctoral thesis of the corresponding author.展开更多
Electronic warfare simulation can allow the realistic evaluation of the performance ofequipments and techniques, and it can also allow the realistic training of individualsunder conditions that, in real life, might ki...Electronic warfare simulation can allow the realistic evaluation of the performance ofequipments and techniques, and it can also allow the realistic training of individualsunder conditions that, in real life, might kill them. We propose a new scheme of EWsimulation system based on SystemVue. This paper mainly expounds the structure ofsystem and the key technology of subsystem establishment. As a proof of concept, aradar electronic reconnaissance simulation experiment is explained in this paper. Andthe results verify the feasibility of the scheme.展开更多
Congestion control is among primary topics in computer network in which random early detection(RED)method is one of its common techniques.Nevertheless,RED suffers from drawbacks in particular when its“average queue l...Congestion control is among primary topics in computer network in which random early detection(RED)method is one of its common techniques.Nevertheless,RED suffers from drawbacks in particular when its“average queue length”is set below the buffer’s“minimum threshold”position which makes the router buffer quickly overflow.To deal with this issue,this paper proposes two discrete-time queue analytical models that aim to utilize an instant queue length parameter as a congestion measure.This assigns mean queue length(mql)and average queueing delay smaller values than those for RED and eventually reduces buffers overflow.A comparison between RED and the proposed analytical models was conducted to identify the model that offers better performance.The proposed models outperform the classic RED in regards to mql and average queueing delay measures when congestion exists.This work also compares one of the proposed models(RED-Linear)with another analytical model named threshold-based linear reduction of arrival rate(TLRAR).The results of the mql,average queueing delay and the probability of packet loss for TLRAR are deteriorated when heavy congestion occurs,whereas,the results of our RED-Linear were not impacted and this shows superiority of our model.展开更多
Establishing a mathematical supply-chain model is a proposition that has received attention due to its inherent benefits of evolving global supply-chain efficiencies.This paper discusses the prevailing relationships f...Establishing a mathematical supply-chain model is a proposition that has received attention due to its inherent benefits of evolving global supply-chain efficiencies.This paper discusses the prevailing relationships found within apparel supply-chain environments,and contemplates the complex issues indicated for constituting a mathematical model.Principal results identified within the data suggest,that the multifarious nature of global supply-chain activities require a degree of simplification in order to fully dilate the necessary factors which affect,each subsection of the chain.Subsequently,the research findings allowed the division of supply-chain components into subsections,which amassed a coherent method of product development activity.Concurrently,the supply-chain model was found to allow systematic mathematical formulae analysis,of cost and time,within the multiple contexts of each subsection encountered.The paper indicates the supplychain model structure,the mathematics,and considers how product analysis of cost and time can improve the comprehension of product lifecycle management.展开更多
In this paper,the effect of geometrical parameters of centrifugal fan on performance has been presented with a system approach.Often,the operators or the design engineers focus on the immediate requirements of the eng...In this paper,the effect of geometrical parameters of centrifugal fan on performance has been presented with a system approach.Often,the operators or the design engineers focus on the immediate requirements of the engine/equipment and they neglect the broader question of how the fan parameters are affecting the equipment.For instance,change in fan angles will change the performance e.g.,airflow rates and efficiency.However,it also affects the contaminants build-up on the blades.Blade angle with higher angle of attack will promote contaminants build-up on blade surfaces,which in turn causes performance degradation and unstable operation.The system approach in fan parameter selection will result in a more reliable system.Significance of other fan parameters is also discussed.We present an experimental setup and validated computational fluid dynamic(CFD)model.Fan power consumption is determined experimentally and compared with the CFD model.Further parametric simulations were carried out to investigate the effect on fan performance.Effect of system resistance,inlet and outlet angle,blade thickness,and no-uniform spaced blades has been described with discussions on industrial relevance.A fan with higher flow rates is desirable to reduce engine temperatures and enhance the durability.However,higher flow rates result in more fan power consumption at a given fan speed.The test results suggest that a fan with higher power coefficient does not affect the vehicle’s mileage significantly.This paper will help design engineers in making informed decision about the interaction between the fans and system,and its effect during the operation.展开更多
In this paper,using the theoretical analysis method,according to the actual structure of the hanging leaf spring of the traction motor mounted on the frame,the lateral force model of the hanging leaf spring of the tra...In this paper,using the theoretical analysis method,according to the actual structure of the hanging leaf spring of the traction motor mounted on the frame,the lateral force model of the hanging leaf spring of the traction motor was established.Then,through theoretical deduction,the deformation analytical calculation formula and the stress analytical calculation formula of the hanging leaf spring were established.The correctness of the leaf spring’s lateral force model was established and its deformation and stress analytical formulae were verified using ANSYS finite element analysis software.Based on this,according to the deformation analytical formula and the stress analytical formula of the leaf spring established,the influence of the main structural parameters on the mechanical characteristics of the leaf spring was discussed,and the reliability of the analytical analysis method of the lateral mechanical characteristics of the traction motor hanging leaf spring was verified by the loading–unloading test.The results show that the deformation and the load of the leaf spring change linearly.The changes of leaf spring’s stress at different positions can be considered as being composed of three sections:a linear change section in the root,a nonlinear change section in the middle,and a nonlinear change section in the end.In the structural parameters,the end thickness h2 has the greatest influence on the stiffness and the stress of the leaf spring,and the maximum thickness of the leaf spring eye h1 has the least influence on the stiffness and the stress of the leaf spring.The influence degree of other parameters on the stiffness of the leaf spring is h_(3),L_(1),L_(3),L_(2) in order,and the influence degree on the stress of the leaf spring is h_(3),L_(1),L_(2),L_(3) in order.In addition,when the root thickness h_(3) is greater than a certain value,the maximum stress point of the leaf spring appears at the end position L_(2).This study can provide a useful reference for the intelligent forward design and the rapid analysis of the mechanical characteristics of high-speed train traction motor hanging leaf spring.展开更多
In this paper,a nonlinear time-fractional coupled diffusion system is solved by using a mixed finite element(MFE)method in space combined with L1-approximation and implicit second-order backward difference scheme in t...In this paper,a nonlinear time-fractional coupled diffusion system is solved by using a mixed finite element(MFE)method in space combined with L1-approximation and implicit second-order backward difference scheme in time.The stability for nonlinear fully discrete finite element scheme is analyzed and a priori error estimates are derived.Finally,some numerical tests are shown to verify our theoretical analysis.展开更多
This study presents the development of computationally efficient coupling of Navier–Stokes Computational Fluid Dynamics(CFD)with a helicopter flight dynamics model with the ultimate goal of real-time simulation of ai...This study presents the development of computationally efficient coupling of Navier–Stokes Computational Fluid Dynamics(CFD)with a helicopter flight dynamics model with the ultimate goal of real-time simulation of airwake effects in the helicopter/ship Dynamic Interface(DI).The flight dynamics model is free to move within a computational domain,where the main rotor forces are converted to source terms in the momentum equations of the CFD solution using an actuator disk model.Simultaneously,the CFD solver calculates induced velocities that are fed back to the simulation and affect the aerodynamic loads in the flight dynamics.The CFD solver models the inflow,ground effect and interactional aerodynamics in the flight dynamics simulation,and these calculations can be coupled with the solution of the external flow(e.g.,ship airwake effects).The simulation framework for fully-coupled pilot-in-the-loop(PIL)flight dynamics/CFD is demonstrated for a simplified shedding wake.Initial tests were performed with 0.38 million structured grid cells running on 352 processors and showed near-real-time performance.Improvements to the coupling interface are described that allow the simulation run at near-real-time execution speeds on currently available computing platforms.Improvements in computing hardware are expected to allow real-time simulations.展开更多
Dendritic spine plays an important role in calcium regulation in a neuron cell.It serves as a storage site for synaptic strength and receives input from a single synapse of axon.In order to understand the calcium dyna...Dendritic spine plays an important role in calcium regulation in a neuron cell.It serves as a storage site for synaptic strength and receives input from a single synapse of axon.In order to understand the calcium dynamics in a neuron cell,it is crucial to understand the calcium dynamics in dendritic spines.In this paper,an attempt has been made to study the calcium dynamics due to the exogenous buffers,in dendritic spines with the help of a sectional model.The compartments of dendritic spines are discretized using triangular elements.Appropriate boundary conditions have been framed.Finite element method has been employed to obtain the solution in the region for a two-dimensional unsteady state case.MATLAB 7.11 is used for simulation of the problem and numerical computations.The numerical results have been used to study the effect of exogenous buffers on calcium distribution in dendritic spines.展开更多
Soft computing has attracted many research scientists,decision makers and practicing researchers in recent years as powerful computational intelligent techniques,for solving unlimited number of complex real-world prob...Soft computing has attracted many research scientists,decision makers and practicing researchers in recent years as powerful computational intelligent techniques,for solving unlimited number of complex real-world problems particularly related to research area of optimization.Under the uncertain and turbulence environment,classical and traditional approaches are unable to obtain a complete solution with satisfaction for the real-world problems on optimization.Therefore,new global optimization methods are required to handle these issues seriously.One such method is hybrid Genetic algorithms and Pattern search,a generic,flexible,robust,and versatile framework for solving complex problems of global optimization and search in real-world applications.展开更多
A perturbation algorithm Multiple Scales Modified Lindstedt–Poincare(MSMLP),combination of method of Multiple Scales and modified Lindstedt–Poincare is proposed for the solution of Quintic Duffing equation which com...A perturbation algorithm Multiple Scales Modified Lindstedt–Poincare(MSMLP),combination of method of Multiple Scales and modified Lindstedt–Poincare is proposed for the solution of Quintic Duffing equation which combines the advantages of both the methods.Solution obtained by the MSMLP method is compared with the Multiple Scales method and accurate closed form approximate solution of the Quintic Duffing equation.The proposed method produces better results for a wide range of amplitude values of oscillations and strong nonlinearities.Numerical simulation has been performed in MATHEMATICA 7.0.展开更多
We consider sequential auctions wherein seller and bidder agents need to price goods on sale at the‘right’market price.We propose algorithms based on a binomial model for both the seller and buyer.Then,we consider t...We consider sequential auctions wherein seller and bidder agents need to price goods on sale at the‘right’market price.We propose algorithms based on a binomial model for both the seller and buyer.Then,we consider the problem of calibrating pricing models to market data.To this end,we studied a stochastic volatility model used for option pricing,derived,and analyzed Monte Carlo estimators for computing the gradient of a certain payoff function using Finite Differencing and Algorithmic Differentiation.We then assessed the accuracy and efficiency of both methods as well as their impacts into the optimization algorithm.Numerical results are presented and discussed.This work can benefit those engaged in electronic trading or investors in financial products with the need for fast and more precise predictions of future market data.展开更多
In this study,the flow structure and effect of different pump rotational speeds on a centrifugal pump’s performance are experimentally and numerically investigated.The internal flow field pattern within the pump has ...In this study,the flow structure and effect of different pump rotational speeds on a centrifugal pump’s performance are experimentally and numerically investigated.The internal flow field pattern within the pump has been analyzed and discussed using the CFD technique.The numerical results are compared with experimental data under a wide range of operating conditions.The comparison results between them have indicated a considerable agreement.The pressure variations are gradually increasing from inlet to outlet impeller of the pump.The results note that when the impeller rotates near the tongue region,the pressure in this region was higher than in other parts.Also,the interaction between the impeller and volute tongue region is actually according to the impeller blades’relative position concerning the tongue region.Furthermore,the pressure and velocity variations within a centrifugal pump increase with rotational impeller speed.展开更多
Just-in-time(JIT)part feeding is adopted by more and more automobile producers.Based on this part feeding policy,vehicles perform their assigned routes cyclically and provide stations with the exact quantity of parts ...Just-in-time(JIT)part feeding is adopted by more and more automobile producers.Based on this part feeding policy,vehicles perform their assigned routes cyclically and provide stations with the exact quantity of parts required until the next arrival of the vehicle.However,if there are uncertain travel times,a shortage of materials in stations will be caused.In this paper,the JIT part feeding optimization problem under travel time uncertainty is studied.The uncertain travel time is represented by the interval number according to the actual situation.To minimize the largest possible vehicle trip time,the optimization model is developed based on robust optimization.In the model,a route-dependent uncertain parameter is introduced.Through this model,the route of each vehicle and the parts load needed to be delivered by the vehicle can be calculated.A hybrid simulated annealing algorithm is designed to solve this model.The parts feeding planning for an engine assembly line is taken as an example.By the Monte Carlo simulation,the relationship between the line stoppage probability and the uncertain parameter is studied to obtain the final solution.The effectiveness of the method is demonstrated by this case study.展开更多
文摘The fuzzy variable fractional differential equations(FVFDEs)play a very important role in mathematical modeling of COVID-19.The scientists are studying and developing several aspects of these COVID-19 models.The existence and uniqueness of the solution,stability analysis are the most common and important study aspects.There is no study in the literature to establish the existence,uniqueness,and UH stability for fuzzy variable fractional(FVF)order COVID-19 models.Due to high demand of this study,we investigate results for the existence,uniqueness,and UH stability for the considered COVID-19 model based on FVFDEs using a fixed point theory approach with the singular operator.Additionally,discuss the maximal/minimal solution for the FVFDE of the COVID-19 model.
文摘In this paper,time-fractional Sharma-Tasso-Olver(STO)equation has been solved numerically through the Petrov-Galerkin approach utilizing a quintic B-spline function as the test function and a linear hat function as the trial function.The Petrov-Galerkin technique is effectively implemented to the fractional STO equation for acquiring the approximate solution numerically.The numerical outcomes are observed in adequate compatibility with those obtained from variational iteration method(VIM)and exact solutions.For fractional order,the numerical outcomes of fractional Sharma-Tasso-Olver equations are also compared with those obtained by variational iteration method(VIM)in Song et al.[Song L.,Wang Q.,Zhang H.,Rational approximation solution of the fractional Sharma-Tasso-Olver equation,J.Comput.Appl.Math.224:210-218,2009].Numerical experiments exhibit the accuracy and efficiency of the approach in order to solve nonlinear fractional STO equation.
文摘The major goal of this paper is to isolate tumor region from nontumor regions and the estimation of tumor volume.Accurate segmentation is not an easy task due to the varying size,shape and location of the tumor.After segmentation,volume estimation is necessary in order to accurately estimate the tumor volume.By exactly estimating the volume of abnormal tissue,physicians can do excellent prognosis,clinical planning and dosage estimation.This paper describes a new Euclidean Similarity factor(ESF)based active contour model with deep learning for segmenting the tumor region into complete,core and enhanced tumor portions.Initially,the ESF considers the spatial distances and intensity differences of the region automatically to detect the tumor region.It preserves the image details but removes the noisy details.Then,the 3D Convolutional Neural Network(3D CNN)segments the tumor by automatically extracting spatiotemporal features.Finally,the extended shoelace method estimates the volume of the tumor accurately for n-sided polygons.The simulation result achieves a high accuracy of 92%and Jaccard index of 0.912 and computes the tumor volume with effective performance than existing approaches.
文摘The main objective of this work is to check the compatibility of Finite element method(FEM)to determine the modal parameters of the rotor system and to compare the results with analytical method.Current work is an attempt to implement different finite element(FE)models for the estimation of modal parameters.Two different order elements from Beam,Axisymmetric and Solid FE models are considered.The analysis is carried out on the rotor system and the accuracy of the results and the computation time of the FE models are estimated.The FE results are compared with the analytical method.It is observed that FE model can be used to simulate even at higher order frequencies,which is a limitation of analytical model.The analysis shows that the FE results closely match with analytical method and also the study summarizes that proper choosing of FE helps in developing rotor models in both a desirable accuracy and efficiency.Finally,a Campbell diagram is generated using the analytical method and FEM.The critical speeds are also calculated from the Campbell diagram.The closeness of the results between the two methods is checked.
文摘We demonstrate a new nonuniform mesh finite difference method to obtain accurate solutions for the elliptic partial differential equations in two dimensions with nonlinear first-order partial derivative terms.The method will be based on a geometric grid network area and included among the most stable differencing scheme in which the nine-point spatial finite differences are implemented,thus arriving at a compact formulation.In general,a third order of accuracy has been achieved and a fourth-order truncation error in the solution values will follow as a particular case.The efficiency of using geometric mesh ratio parameter has been shown with the help of illustrations.The convergence of the scheme has been established using the matrix analysis,and irreducibility is proved with the help of strongly connected characteristics of the iteration matrix.The difference scheme has been applied to test convection diffusion equation,steady state Burger’s equation,ocean model and a semi-linear elliptic equation.The computational results confirm the theoretical order and accuracy of the method.
文摘In this paper,we studied a two-parameter transmuted model of Log-logistic distribution(LLD)using the quadratic rank transmutation map technique studied by Shaw and Buckley1 as a new survival model in medical sciences and other applied fields.Statistical properties of Transmuted LLD(TLLD)are discussed comprehensively.Robust measures of skewness and kurtosis of the proposed model have also been discussed along with graphical overview.The estimation of the model parameters is performed by Maximum Likelihood(ML)method followed by a Monte Carlo(MC)simulation procedure to investigate the performance of the ML estimators and the asymptotic confidence intervals of the parameters.Applications of the proposed model to real-life data are also presented.
文摘Personalization is the adaptation of the services to fit the user’s interests,characteristics and needs.The key to effective personalization is user profiling.Apart from traditional collaborative and content-based approaches,a number of classification and clustering algorithms have been used to classify user related information to create user profiles.However,they are not able to achieve accurate user profiles.In this paper,we present a new clustering algorithm,namely Multi-Dimensional Clustering(MDC),to determine user profiling.The MDC is a version of the Instance-Based Learner(IBL)algorithm that assigns weights to feature values and considers these weights for the clustering.Three feature weight methods are proposed for the MDC and,all three,have been tested and evaluated.Simulations were conducted with using two sets of user profile datasets,which are the training(includes 10,000 instances)and test(includes 1000 instances)datasets.These datasets reflect each user’s personal information,preferences and interests.Additional simulations and comparisons with existing weighted and non-weighted instance-based algorithms were carried out in order to demonstrate the performance of proposed algorithm.Experimental results using the user profile datasets demonstrate that the proposed algorithm has better clustering accuracy performance compared to other algorithms.This work is based on the doctoral thesis of the corresponding author.
文摘Electronic warfare simulation can allow the realistic evaluation of the performance ofequipments and techniques, and it can also allow the realistic training of individualsunder conditions that, in real life, might kill them. We propose a new scheme of EWsimulation system based on SystemVue. This paper mainly expounds the structure ofsystem and the key technology of subsystem establishment. As a proof of concept, aradar electronic reconnaissance simulation experiment is explained in this paper. Andthe results verify the feasibility of the scheme.
文摘Congestion control is among primary topics in computer network in which random early detection(RED)method is one of its common techniques.Nevertheless,RED suffers from drawbacks in particular when its“average queue length”is set below the buffer’s“minimum threshold”position which makes the router buffer quickly overflow.To deal with this issue,this paper proposes two discrete-time queue analytical models that aim to utilize an instant queue length parameter as a congestion measure.This assigns mean queue length(mql)and average queueing delay smaller values than those for RED and eventually reduces buffers overflow.A comparison between RED and the proposed analytical models was conducted to identify the model that offers better performance.The proposed models outperform the classic RED in regards to mql and average queueing delay measures when congestion exists.This work also compares one of the proposed models(RED-Linear)with another analytical model named threshold-based linear reduction of arrival rate(TLRAR).The results of the mql,average queueing delay and the probability of packet loss for TLRAR are deteriorated when heavy congestion occurs,whereas,the results of our RED-Linear were not impacted and this shows superiority of our model.
文摘Establishing a mathematical supply-chain model is a proposition that has received attention due to its inherent benefits of evolving global supply-chain efficiencies.This paper discusses the prevailing relationships found within apparel supply-chain environments,and contemplates the complex issues indicated for constituting a mathematical model.Principal results identified within the data suggest,that the multifarious nature of global supply-chain activities require a degree of simplification in order to fully dilate the necessary factors which affect,each subsection of the chain.Subsequently,the research findings allowed the division of supply-chain components into subsections,which amassed a coherent method of product development activity.Concurrently,the supply-chain model was found to allow systematic mathematical formulae analysis,of cost and time,within the multiple contexts of each subsection encountered.The paper indicates the supplychain model structure,the mathematics,and considers how product analysis of cost and time can improve the comprehension of product lifecycle management.
文摘In this paper,the effect of geometrical parameters of centrifugal fan on performance has been presented with a system approach.Often,the operators or the design engineers focus on the immediate requirements of the engine/equipment and they neglect the broader question of how the fan parameters are affecting the equipment.For instance,change in fan angles will change the performance e.g.,airflow rates and efficiency.However,it also affects the contaminants build-up on the blades.Blade angle with higher angle of attack will promote contaminants build-up on blade surfaces,which in turn causes performance degradation and unstable operation.The system approach in fan parameter selection will result in a more reliable system.Significance of other fan parameters is also discussed.We present an experimental setup and validated computational fluid dynamic(CFD)model.Fan power consumption is determined experimentally and compared with the CFD model.Further parametric simulations were carried out to investigate the effect on fan performance.Effect of system resistance,inlet and outlet angle,blade thickness,and no-uniform spaced blades has been described with discussions on industrial relevance.A fan with higher flow rates is desirable to reduce engine temperatures and enhance the durability.However,higher flow rates result in more fan power consumption at a given fan speed.The test results suggest that a fan with higher power coefficient does not affect the vehicle’s mileage significantly.This paper will help design engineers in making informed decision about the interaction between the fans and system,and its effect during the operation.
基金This work is supported by the National Natural Science Foundation of China(51575325)Key R&D Projects in Shandong Province(GG201703070088).
文摘In this paper,using the theoretical analysis method,according to the actual structure of the hanging leaf spring of the traction motor mounted on the frame,the lateral force model of the hanging leaf spring of the traction motor was established.Then,through theoretical deduction,the deformation analytical calculation formula and the stress analytical calculation formula of the hanging leaf spring were established.The correctness of the leaf spring’s lateral force model was established and its deformation and stress analytical formulae were verified using ANSYS finite element analysis software.Based on this,according to the deformation analytical formula and the stress analytical formula of the leaf spring established,the influence of the main structural parameters on the mechanical characteristics of the leaf spring was discussed,and the reliability of the analytical analysis method of the lateral mechanical characteristics of the traction motor hanging leaf spring was verified by the loading–unloading test.The results show that the deformation and the load of the leaf spring change linearly.The changes of leaf spring’s stress at different positions can be considered as being composed of three sections:a linear change section in the root,a nonlinear change section in the middle,and a nonlinear change section in the end.In the structural parameters,the end thickness h2 has the greatest influence on the stiffness and the stress of the leaf spring,and the maximum thickness of the leaf spring eye h1 has the least influence on the stiffness and the stress of the leaf spring.The influence degree of other parameters on the stiffness of the leaf spring is h_(3),L_(1),L_(3),L_(2) in order,and the influence degree on the stress of the leaf spring is h_(3),L_(1),L_(2),L_(3) in order.In addition,when the root thickness h_(3) is greater than a certain value,the maximum stress point of the leaf spring appears at the end position L_(2).This study can provide a useful reference for the intelligent forward design and the rapid analysis of the mechanical characteristics of high-speed train traction motor hanging leaf spring.
基金the National Natural Science Fund(11661058,11301258,11361035)the Natural Science Fund of Inner Mongolia Autonomous Region(2016MS0102,2015MS0101)+1 种基金the Scientific Research Projection of Higher Schools of Inner Mongolia(NJZZ12011)the National Undergraduate Innovative Training Project(201510126026).
文摘In this paper,a nonlinear time-fractional coupled diffusion system is solved by using a mixed finite element(MFE)method in space combined with L1-approximation and implicit second-order backward difference scheme in time.The stability for nonlinear fully discrete finite element scheme is analyzed and a priori error estimates are derived.Finally,some numerical tests are shown to verify our theoretical analysis.
基金the Office of Naval Research,ONR,under Grant/Contract numbers N00014-14-C-0020(PSU)and N00014-13-C-0456(CRAFT Tech).
文摘This study presents the development of computationally efficient coupling of Navier–Stokes Computational Fluid Dynamics(CFD)with a helicopter flight dynamics model with the ultimate goal of real-time simulation of airwake effects in the helicopter/ship Dynamic Interface(DI).The flight dynamics model is free to move within a computational domain,where the main rotor forces are converted to source terms in the momentum equations of the CFD solution using an actuator disk model.Simultaneously,the CFD solver calculates induced velocities that are fed back to the simulation and affect the aerodynamic loads in the flight dynamics.The CFD solver models the inflow,ground effect and interactional aerodynamics in the flight dynamics simulation,and these calculations can be coupled with the solution of the external flow(e.g.,ship airwake effects).The simulation framework for fully-coupled pilot-in-the-loop(PIL)flight dynamics/CFD is demonstrated for a simplified shedding wake.Initial tests were performed with 0.38 million structured grid cells running on 352 processors and showed near-real-time performance.Improvements to the coupling interface are described that allow the simulation run at near-real-time execution speeds on currently available computing platforms.Improvements in computing hardware are expected to allow real-time simulations.
文摘Dendritic spine plays an important role in calcium regulation in a neuron cell.It serves as a storage site for synaptic strength and receives input from a single synapse of axon.In order to understand the calcium dynamics in a neuron cell,it is crucial to understand the calcium dynamics in dendritic spines.In this paper,an attempt has been made to study the calcium dynamics due to the exogenous buffers,in dendritic spines with the help of a sectional model.The compartments of dendritic spines are discretized using triangular elements.Appropriate boundary conditions have been framed.Finite element method has been employed to obtain the solution in the region for a two-dimensional unsteady state case.MATLAB 7.11 is used for simulation of the problem and numerical computations.The numerical results have been used to study the effect of exogenous buffers on calcium distribution in dendritic spines.
文摘Soft computing has attracted many research scientists,decision makers and practicing researchers in recent years as powerful computational intelligent techniques,for solving unlimited number of complex real-world problems particularly related to research area of optimization.Under the uncertain and turbulence environment,classical and traditional approaches are unable to obtain a complete solution with satisfaction for the real-world problems on optimization.Therefore,new global optimization methods are required to handle these issues seriously.One such method is hybrid Genetic algorithms and Pattern search,a generic,flexible,robust,and versatile framework for solving complex problems of global optimization and search in real-world applications.
基金support provided by the University Grant Commission,New Delhi,Government of India,under research grant no.37-515/2009(SR).
文摘A perturbation algorithm Multiple Scales Modified Lindstedt–Poincare(MSMLP),combination of method of Multiple Scales and modified Lindstedt–Poincare is proposed for the solution of Quintic Duffing equation which combines the advantages of both the methods.Solution obtained by the MSMLP method is compared with the Multiple Scales method and accurate closed form approximate solution of the Quintic Duffing equation.The proposed method produces better results for a wide range of amplitude values of oscillations and strong nonlinearities.Numerical simulation has been performed in MATHEMATICA 7.0.
文摘We consider sequential auctions wherein seller and bidder agents need to price goods on sale at the‘right’market price.We propose algorithms based on a binomial model for both the seller and buyer.Then,we consider the problem of calibrating pricing models to market data.To this end,we studied a stochastic volatility model used for option pricing,derived,and analyzed Monte Carlo estimators for computing the gradient of a certain payoff function using Finite Differencing and Algorithmic Differentiation.We then assessed the accuracy and efficiency of both methods as well as their impacts into the optimization algorithm.Numerical results are presented and discussed.This work can benefit those engaged in electronic trading or investors in financial products with the need for fast and more precise predictions of future market data.
文摘In this study,the flow structure and effect of different pump rotational speeds on a centrifugal pump’s performance are experimentally and numerically investigated.The internal flow field pattern within the pump has been analyzed and discussed using the CFD technique.The numerical results are compared with experimental data under a wide range of operating conditions.The comparison results between them have indicated a considerable agreement.The pressure variations are gradually increasing from inlet to outlet impeller of the pump.The results note that when the impeller rotates near the tongue region,the pressure in this region was higher than in other parts.Also,the interaction between the impeller and volute tongue region is actually according to the impeller blades’relative position concerning the tongue region.Furthermore,the pressure and velocity variations within a centrifugal pump increase with rotational impeller speed.
基金This research received no external funding.This research is supported by the National Key Research and Development Program of China(Grant No.2017YFB1301600)。
文摘Just-in-time(JIT)part feeding is adopted by more and more automobile producers.Based on this part feeding policy,vehicles perform their assigned routes cyclically and provide stations with the exact quantity of parts required until the next arrival of the vehicle.However,if there are uncertain travel times,a shortage of materials in stations will be caused.In this paper,the JIT part feeding optimization problem under travel time uncertainty is studied.The uncertain travel time is represented by the interval number according to the actual situation.To minimize the largest possible vehicle trip time,the optimization model is developed based on robust optimization.In the model,a route-dependent uncertain parameter is introduced.Through this model,the route of each vehicle and the parts load needed to be delivered by the vehicle can be calculated.A hybrid simulated annealing algorithm is designed to solve this model.The parts feeding planning for an engine assembly line is taken as an example.By the Monte Carlo simulation,the relationship between the line stoppage probability and the uncertain parameter is studied to obtain the final solution.The effectiveness of the method is demonstrated by this case study.
