This study numerically examines the heat and mass transfer characteristics of two ternary nanofluids via converging and diverg-ing channels.Furthermore,the study aims to assess two ternary nanofluids combinations to d...This study numerically examines the heat and mass transfer characteristics of two ternary nanofluids via converging and diverg-ing channels.Furthermore,the study aims to assess two ternary nanofluids combinations to determine which configuration can provide better heat and mass transfer and lower entropy production,while ensuring cost efficiency.This work bridges the gap be-tween academic research and industrial feasibility by incorporating cost analysis,entropy generation,and thermal efficiency.To compare the velocity,temperature,and concentration profiles,we examine two ternary nanofluids,i.e.,TiO_(2)+SiO_(2)+Al_(2)O_(3)/H_(2)O and TiO_(2)+SiO_(2)+Cu/H_(2)O,while considering the shape of nanoparticles.The velocity slip and Soret/Dufour effects are taken into consideration.Furthermore,regression analysis for Nusselt and Sherwood numbers of the model is carried out.The Runge-Kutta fourth-order method with shooting technique is employed to acquire the numerical solution of the governed system of ordinary differential equations.The flow pattern attributes of ternary nanofluids are meticulously examined and simulated with the fluc-tuation of flow-dominating parameters.Additionally,the influence of these parameters is demonstrated in the flow,temperature,and concentration fields.For variation in Eckert and Dufour numbers,TiO_(2)+SiO_(2)+Al_(2)O_(3)/H_(2)O has a higher temperature than TiO_(2)+SiO_(2)+Cu/H_(2)O.The results obtained indicate that the ternary nanofluid TiO_(2)+SiO_(2)+Al_(2)O_(3)/H_(2)O has a higher heat transfer rate,lesser entropy generation,greater mass transfer rate,and lower cost than that of TiO_(2)+SiO_(2)+Cu/H_(2)O ternary nanofluid.展开更多
In this paper,a new technique is introduced to construct higher-order iterative methods for solving nonlinear systems.The order of convergence of some iterative methods can be improved by three at the cost of introduc...In this paper,a new technique is introduced to construct higher-order iterative methods for solving nonlinear systems.The order of convergence of some iterative methods can be improved by three at the cost of introducing only one additional evaluation of the function in each step.Furthermore,some new efficient methods with a higher-order of convergence are obtained by using only a single matrix inversion in each iteration.Analyses of convergence properties and computational efficiency of these new methods are made and testified by several numerical problems.By comparison,the new schemes are more efficient than the corresponding existing ones,particularly for large problem sizes.展开更多
The organization of biological neuronal networks into functional modules has intrigued scientists and inspired engineers to develop artificial systems.These networks are characterized by two key properties.First,they ...The organization of biological neuronal networks into functional modules has intrigued scientists and inspired engineers to develop artificial systems.These networks are characterized by two key properties.First,they exhibit dense interconnectivity(Braitenburg and Schüz,1998;Campagnola et al.,2022).The strength and probability of connectivity depend on cell type,inter-neuronal distance,and species.Still,every cortical neuron receives input from thousands of other neurons while transmitting output to a similar number of neurons.Second,communication between neurons occurs primarily via chemical or electrical synapses.展开更多
The harmonic balance method(HBM)has been widely applied to get the periodic solution of nonlinear systems,however,its convergence rate as well as computation efficiency is dramatically degraded when the system is high...The harmonic balance method(HBM)has been widely applied to get the periodic solution of nonlinear systems,however,its convergence rate as well as computation efficiency is dramatically degraded when the system is highly non-smooth,e.g.,discontinuous.In order to accelerate the convergence,an enriched HBM is developed in this paper where the non-smooth Bernoulli bases are additionally introduced to enrich the conventional Fourier bases.The basic idea behind is that the convergence rate of the HB solution,as a truncated Fourier series,can be improved if the smoothness of the solution becomes finer.Along this line,using non-smooth Bernoulli bases can compensate the highly non-smooth part of the solution and then,the smoothness of the residual part for Fourier approximation is improved so as to achieve accelerated convergence.Numerical examples are conducted on systems with non-smooth restoring and/or external forces.The results confirm that the proposed enriched HBM indeed increases the convergence rate and the increase becomes more significant if more non-smooth bases are used.展开更多
Recently,inspired by a modified generalized shift-splitting iteration method for complex symmetric linear systems,we propose two variants of the modified generalized shift-splitting iteration(MGSS)methods for solving ...Recently,inspired by a modified generalized shift-splitting iteration method for complex symmetric linear systems,we propose two variants of the modified generalized shift-splitting iteration(MGSS)methods for solving com-plex symmetric linear systems.One is a parameterized MGSS iteration method and the other is a modified parameterized MGSS iteration method.We prove that the proposed methods are convergent under appropriate constraints on the parameters.In addition,we also give the eigenvalue distributions of differ-ent preconditioned matrices to verify the effectiveness of the preconditioners proposed in this paper.展开更多
A new type of composite CVT(continuously variable transmission) systemsfeatured by power flow divergence and dual-mode convergence, capable of improving CVT's efficiencyand power capacity or making AMTs(automated ...A new type of composite CVT(continuously variable transmission) systemsfeatured by power flow divergence and dual-mode convergence, capable of improving CVT's efficiencyand power capacity or making AMTs(automated manual transmissions) become continuously variable, isstudied. With specific mechano-mechanical and electromechanical composite CVT systems as detailedexamples, its basic working principles are expatiated. General methods and key points in designingand realizing such systems are also analyzed and discussed.展开更多
An extreme rainfall event occurred over Hangzhou,China,during the afternoon hours on 24 June 2013.This event occurred under suitable synoptic conditions and the maximum 4-h cumulative rainfall amount was over 150 mm.T...An extreme rainfall event occurred over Hangzhou,China,during the afternoon hours on 24 June 2013.This event occurred under suitable synoptic conditions and the maximum 4-h cumulative rainfall amount was over 150 mm.This rainfall event had two major rainbands.One was caused by a quasi-stationary convective line,and the other by a backbuilding convective line related to the interaction of the outflow boundary from the first rainband and an existing low-level mesoscale convergence line associated with a mei-yu frontal system.The rainfall event lasted 4 h,while the back-building process occurred in 2 h when the extreme rainfall center formed.So far,few studies have examined the back-building processes in the mei-yu season that are caused by the interaction of a mesoscale convergence line and a convective cold pool.The two rainbands are successfully reproduced by the Weather Research and Forecasting(WRF)model with fourlevel,two-way interactive nesting.In the model,new cells repeatedly occur at the west side of older cells,and the backbuilding process occurs in an environment with large CAPE,a low LFC,and plenty of water vapor.Outflows from older cells enhance the low-level convergence that forces new cells.High precipitation efficiency of the back-building training cells leads to accumulated precipitation of over 150 mm.Sensitivity experiments without evaporation of rainwater show that the convective cold pool plays an important role in the organization of the back-building process in the current extreme precipitation case.展开更多
This article focuses on asymptotic precision motion control for electro-hydraulic axis systems under unknown time-variant parameters,mismatched and matched disturbances.Different from the traditional adaptive results ...This article focuses on asymptotic precision motion control for electro-hydraulic axis systems under unknown time-variant parameters,mismatched and matched disturbances.Different from the traditional adaptive results that are applied to dispose of unknown constant parameters only,the unique feature is that an adaptive-gain nonlinear term is introduced into the control design to handle unknown time-variant parameters.Concurrently both mismatched and matched disturbances existing in electro-hydraulic axis systems can also be addressed in this way.With skillful integration of the backstepping technique and the adaptive control,a synthesized controller framework is successfully developed for electro-hydraulic axis systems,in which the coupled interaction between parameter estimation and disturbance estimation is avoided.Accordingly,this designed controller has the capacity of low-computation costs and simpler parameter tuning when compared to the other ones that integrate the adaptive control and observer/estimator-based technique to dividually handle parameter uncertainties and disturbances.Also,a nonlinear filter is designed to eliminate the“explosion of complexity”issue existing in the classical back-stepping technique.The stability analysis uncovers that all the closed-loop signals are bounded and the asymptotic tracking performance is also assured.Finally,contrastive experiment results validate the superiority of the developed method as well.展开更多
In this paper,for Multi-Spacecraft System(MSS)with a directed communication topology link and a static virtual leader,a controller is proposed to realize attitude consensus and attitude stabilization with stochastic l...In this paper,for Multi-Spacecraft System(MSS)with a directed communication topology link and a static virtual leader,a controller is proposed to realize attitude consensus and attitude stabilization with stochastic links failure and actuator saturation.First,an MSS attitude error model suitable for a directed topology link and with a static virtual leader based on SO(3)is derived,which considers that the attitude error on SO(3)cannot be defined based on algebraic subtraction.Then,we design a controller to realize the MSS on SO(3)with attitude consensus and attitude stabilization under stochastic links failure and actuator saturation.Finally,the simulation results of a multi-spacecraft system with stochastic links failure and a static virtual leader spacecraft are demonstrated to illustrate the efficiency of the attitude controller.展开更多
In this short paper,we remove the restrictionγ∈(1,3]that was used in the paper"The rate of convergence of the viscosity method for a nonlinear hyperbolic system"(Nonlinear Analysis,1999,38:435-445)and obta...In this short paper,we remove the restrictionγ∈(1,3]that was used in the paper"The rate of convergence of the viscosity method for a nonlinear hyperbolic system"(Nonlinear Analysis,1999,38:435-445)and obtain a global Holder continuous solution and the convergent rate of the viscosity method for the Cauchy problem of the variant nonisentropic system of polytropic gas for any adiabatic exponentγ>1.展开更多
In this paper,we investigate the distributed estimation problem of continuous-time stochastic dynamic systems over sensor networks when both the system order and parameters are unknown.We propose a local information c...In this paper,we investigate the distributed estimation problem of continuous-time stochastic dynamic systems over sensor networks when both the system order and parameters are unknown.We propose a local information criterion(LIC)based on the L_(0)penalty term.By minimizing LIC at the diffusion time instant and utilizing the continuous-time diffusion least squares algorithm,we obtain a distributed estimation algorithm to simultaneously estimate the unknown order and the parameters of the system.By dealing with the effect of the system noises and the coupling relationship between estimation of system orders and parameters,we establish the almost sure convergence results of the proposed distributed estimation algorithm.Furthermore,we give a simulation example to verify the effectiveness of the distributed algorithm in estimating the system order and parameters.展开更多
Based on the“unidirectional break-up and convergence”geodynamic model,this study investigates the impact of the evolution of the Tethyan domain on the formation of petroleum systems in the Sichuan super basin and ex...Based on the“unidirectional break-up and convergence”geodynamic model,this study investigates the impact of the evolution of the Tethyan domain on the formation of petroleum systems in the Sichuan super basin and explores the enrichment pattern of natural gas.The results show that,firstly,the Sichuan Basin and its surrounding areas have experienced two unidirectional rifting-aggregation cycles triggered by the Proto-Tethys Ocean and the Paleo-Tethys Ocean during the Neoproterozoic to Triassic.During Jurassic–Cenozoic,the Sichuan Basin is incorporated in the circum-Tibetan plateau basin-mountain coupled tectonic domain system.The episodic tectonic movements within the plate control the sedimentary infill styles.Second,the evolution of the Tethyan domain,paleoclimatic environment and major geological events controlled the formation and distribution of high-quality source rocks within the basin.The rift valley and intracratonic rift,passive continental margin slope,and intracratonic sags are favorable areas for the development of source rocks.Third,the evolution of the Tethyan domain,supercontinent cycles,global sea level changes,and tectono-climatic events controlled the distribution of carbonate platform and reservoir-caprock combinations.The cratonic platform margins and sub-platform internal high terrains are key areas for finding carbonate high-energy facies belts.Syndepositional paleo-uplifts and surrounding slopes,regional unconformities,and later faults zone are areas where large-scale carbonate reservoirs are distributed.The regional evaporite or shale caprock are beneficial for the large-scale preservation of oil and gas in the basin.Fourth,the spatio-temporal matching relationship of reservoir forming factors influenced by the early tectonic-sedimentary evolution pattern and the degree of later tectonic modification is the key to oil and gas enrichment.Future oil and gas exploration should focus on potential gas systems during the Sinian rift period,Cambrian pre-salt gas systems in the eastern and southern Sichuan,as well as whole oil and gas systems of Permian and Triassic.展开更多
AIM:To determine the smartphone use patterns and effects of smartphone use on accommodation and convergence system of the eyes among Malaysian teenagers.METHODS:A total of 62 participants aged between 13 and 17y were ...AIM:To determine the smartphone use patterns and effects of smartphone use on accommodation and convergence system of the eyes among Malaysian teenagers.METHODS:A total of 62 participants aged between 13 and 17y were involved.A self-administered questionnaires containing 12 items was used to evaluate the smartphone usage patterns.This was followed by an eye examination,involving a battery of accommodation and convergence assessments before and after the smartphone use.The data analysis comprised descriptive statistics,paired t-test,and correlation coefficients.RESULTS:The use of smartphones is at a high level and at an optimal distance daily,with more than 6h a day watching video films,games,and completing school projects.Majority of the participants not reported eye strain factors and eye prescription changes with the use of digital devices.The use of a smartphone continuously for 30min was found to significantly decrease amplitude of accommodation,accommodative facility,and positive relative accommodation(P<0.001).Meanwhile,the lag of accommodation parameters and negative relative accommodation increased with the use of smartphones significantly(P<0.001).The near point of convergence(NPC)and distance and near negative fusional vergence decreased significantly(P<0.001).The NPC parameter was found to have a weak negative association with the frequency of smartphone use(R=-0.276,P<0.05).CONCLUSION:Frequent and continuous use of smartphones have increased visual stress and resulted in weakness of accommodation and vergence functions.Therefore,frequent break is mandatory when using a smartphone and appropriate visual hygiene,the 20-20-20 rule(every 20min,view something 20 feet away for 20s)are required during smartphone use to maintain visual function.展开更多
In this paper,we established a class of parallel algorithm for solving low-rank tensor completion problem.The main idea is that N singular value decompositions are implemented in N different processors for each slice ...In this paper,we established a class of parallel algorithm for solving low-rank tensor completion problem.The main idea is that N singular value decompositions are implemented in N different processors for each slice matrix under unfold operator,and then the fold operator is used to form the next iteration tensor such that the computing time can be decreased.In theory,we analyze the global convergence of the algorithm.In numerical experiment,the simulation data and real image inpainting are carried out.Experiment results show the parallel algorithm outperform its original algorithm in CPU times under the same precision.展开更多
This paper studies the Smoluchowski–Kramers approximation for a discrete-time dynamical system modeled as the motion of a particle in a force field.We show that the approximation holds for the drift-implicit Euler–M...This paper studies the Smoluchowski–Kramers approximation for a discrete-time dynamical system modeled as the motion of a particle in a force field.We show that the approximation holds for the drift-implicit Euler–Maruyama discretization and derive its convergence rate.In particular,the solution of the discretized system converges to the solution of the first-order limit equation in the mean-square sense,and this convergence is independent of the order in which the mass parameterμand the step size h tend to zero.展开更多
In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradien...In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradient method.Under the condition of standard Wolfe line search,the proposed search direction is the descent direction.For general nonlinear functions,the method is globally convergent.Finally,numerical results show that the proposed method is efficient.展开更多
This paper presents an investigation on the target-guided coordinated control(TACC)of unmanned surface vehicles(USVs).In the scenario of tracking non-cooperative targets,the status information of the target can only b...This paper presents an investigation on the target-guided coordinated control(TACC)of unmanned surface vehicles(USVs).In the scenario of tracking non-cooperative targets,the status information of the target can only be obtained by some USVs.In order to achieve semi-encirclement tracking of noncooperative targets under maritime security conditions,a fixed-time tracking control method based on dynamic surface control(DSC)is proposed in this paper.Firstly,a novel TACC architecture with decoupled kinematic control law and decoupled kinetic control law was designed to reduce the complexity of control system design.Secondly,the proposed DSC-based target-guided kinematic control law including tracking points pre-allocation strategy and sigmoid artificial potential functions(SigAPFs)can avoid collisions during tracking process and optimize kinematic control output.Finally,a fixed-time TACC system was proposed to achieve fast convergence of kinematic and kinetics errors.The effectiveness of the proposed TACC approach in improving target tracking safety and reducing control output chattering was verified by simulation comparison results.展开更多
Analysis and design of linear periodic control systems are closely related to the periodic matrix equations.The biconjugate residual method(BCR for short)have been introduced by Vespucci and Broyden for efficiently so...Analysis and design of linear periodic control systems are closely related to the periodic matrix equations.The biconjugate residual method(BCR for short)have been introduced by Vespucci and Broyden for efficiently solving linear systems Aα=b.The objective of this paper is to provide one new iterative algorithm based on BCR method to find the symmetric periodic solutions of linear periodic matrix equations.This kind of periodic matrix equations has not been dealt with yet.This iterative method is guaranteed to converge in a finite number of steps in the absence of round-off errors.Some numerical results are performed to illustrate the efficiency and feasibility of new method.展开更多
The complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space is studied.By moment inequality and truncation methods,we establish the...The complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space is studied.By moment inequality and truncation methods,we establish the equivalent conditions of complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space.The results complement the corresponding results in probability space to those for sequences of independent,identically distributed random variables under sublinear expectation space.展开更多
基金supported by DST-FIST(Government of India)(Grant No.SR/FIST/MS-1/2017/13)and Seed Money Project(Grant No.DoRDC/733).
文摘This study numerically examines the heat and mass transfer characteristics of two ternary nanofluids via converging and diverg-ing channels.Furthermore,the study aims to assess two ternary nanofluids combinations to determine which configuration can provide better heat and mass transfer and lower entropy production,while ensuring cost efficiency.This work bridges the gap be-tween academic research and industrial feasibility by incorporating cost analysis,entropy generation,and thermal efficiency.To compare the velocity,temperature,and concentration profiles,we examine two ternary nanofluids,i.e.,TiO_(2)+SiO_(2)+Al_(2)O_(3)/H_(2)O and TiO_(2)+SiO_(2)+Cu/H_(2)O,while considering the shape of nanoparticles.The velocity slip and Soret/Dufour effects are taken into consideration.Furthermore,regression analysis for Nusselt and Sherwood numbers of the model is carried out.The Runge-Kutta fourth-order method with shooting technique is employed to acquire the numerical solution of the governed system of ordinary differential equations.The flow pattern attributes of ternary nanofluids are meticulously examined and simulated with the fluc-tuation of flow-dominating parameters.Additionally,the influence of these parameters is demonstrated in the flow,temperature,and concentration fields.For variation in Eckert and Dufour numbers,TiO_(2)+SiO_(2)+Al_(2)O_(3)/H_(2)O has a higher temperature than TiO_(2)+SiO_(2)+Cu/H_(2)O.The results obtained indicate that the ternary nanofluid TiO_(2)+SiO_(2)+Al_(2)O_(3)/H_(2)O has a higher heat transfer rate,lesser entropy generation,greater mass transfer rate,and lower cost than that of TiO_(2)+SiO_(2)+Cu/H_(2)O ternary nanofluid.
基金Supported by the National Natural Science Foundation of China(12061048)NSF of Jiangxi Province(20232BAB201026,20232BAB201018)。
文摘In this paper,a new technique is introduced to construct higher-order iterative methods for solving nonlinear systems.The order of convergence of some iterative methods can be improved by three at the cost of introducing only one additional evaluation of the function in each step.Furthermore,some new efficient methods with a higher-order of convergence are obtained by using only a single matrix inversion in each iteration.Analyses of convergence properties and computational efficiency of these new methods are made and testified by several numerical problems.By comparison,the new schemes are more efficient than the corresponding existing ones,particularly for large problem sizes.
基金supported in part by the Rosetrees Trust(#CF-2023-I-2_113)by the Israel Ministry of Innovation,Science,and Technology(#7393)(to ES).
文摘The organization of biological neuronal networks into functional modules has intrigued scientists and inspired engineers to develop artificial systems.These networks are characterized by two key properties.First,they exhibit dense interconnectivity(Braitenburg and Schüz,1998;Campagnola et al.,2022).The strength and probability of connectivity depend on cell type,inter-neuronal distance,and species.Still,every cortical neuron receives input from thousands of other neurons while transmitting output to a similar number of neurons.Second,communication between neurons occurs primarily via chemical or electrical synapses.
基金supported by the National Natural Science Foundation of China (Grant No. 12372028)the National Key Research and Development Program of China (Grant No. 2020YFC2201101)the Guangdong Basic and Applied Basic Research Foundation (Grant No.2022A1515011809)。
文摘The harmonic balance method(HBM)has been widely applied to get the periodic solution of nonlinear systems,however,its convergence rate as well as computation efficiency is dramatically degraded when the system is highly non-smooth,e.g.,discontinuous.In order to accelerate the convergence,an enriched HBM is developed in this paper where the non-smooth Bernoulli bases are additionally introduced to enrich the conventional Fourier bases.The basic idea behind is that the convergence rate of the HB solution,as a truncated Fourier series,can be improved if the smoothness of the solution becomes finer.Along this line,using non-smooth Bernoulli bases can compensate the highly non-smooth part of the solution and then,the smoothness of the residual part for Fourier approximation is improved so as to achieve accelerated convergence.Numerical examples are conducted on systems with non-smooth restoring and/or external forces.The results confirm that the proposed enriched HBM indeed increases the convergence rate and the increase becomes more significant if more non-smooth bases are used.
基金supported by the National Natural Science Foundation of China(Grant No.12371378)by the Natural Science Foundation of Fujian Province(Grant Nos.2024J01980,2024J08242).
文摘Recently,inspired by a modified generalized shift-splitting iteration method for complex symmetric linear systems,we propose two variants of the modified generalized shift-splitting iteration(MGSS)methods for solving com-plex symmetric linear systems.One is a parameterized MGSS iteration method and the other is a modified parameterized MGSS iteration method.We prove that the proposed methods are convergent under appropriate constraints on the parameters.In addition,we also give the eigenvalue distributions of differ-ent preconditioned matrices to verify the effectiveness of the preconditioners proposed in this paper.
基金This project is supported by National Natural Science Foundation of China (No.50275053) and Provincial Natural Science Fundation of Guangdong (No.020857).
文摘A new type of composite CVT(continuously variable transmission) systemsfeatured by power flow divergence and dual-mode convergence, capable of improving CVT's efficiencyand power capacity or making AMTs(automated manual transmissions) become continuously variable, isstudied. With specific mechano-mechanical and electromechanical composite CVT systems as detailedexamples, its basic working principles are expatiated. General methods and key points in designingand realizing such systems are also analyzed and discussed.
基金supported by the National Natural Science Foundation of China (Grant Nos.41730965, U2242204, and 41175047)the National Key Basic Research and Development Project of China (Grant No.2013CB430104)+2 种基金the Key Project of the Joint Funds of the Natural Science Foundation of Zhejiang Province (Grant No.LZJMZ23D050003financial support from the China Scholarship Council for her visit to CAPSUniversity of Oklahoma
文摘An extreme rainfall event occurred over Hangzhou,China,during the afternoon hours on 24 June 2013.This event occurred under suitable synoptic conditions and the maximum 4-h cumulative rainfall amount was over 150 mm.This rainfall event had two major rainbands.One was caused by a quasi-stationary convective line,and the other by a backbuilding convective line related to the interaction of the outflow boundary from the first rainband and an existing low-level mesoscale convergence line associated with a mei-yu frontal system.The rainfall event lasted 4 h,while the back-building process occurred in 2 h when the extreme rainfall center formed.So far,few studies have examined the back-building processes in the mei-yu season that are caused by the interaction of a mesoscale convergence line and a convective cold pool.The two rainbands are successfully reproduced by the Weather Research and Forecasting(WRF)model with fourlevel,two-way interactive nesting.In the model,new cells repeatedly occur at the west side of older cells,and the backbuilding process occurs in an environment with large CAPE,a low LFC,and plenty of water vapor.Outflows from older cells enhance the low-level convergence that forces new cells.High precipitation efficiency of the back-building training cells leads to accumulated precipitation of over 150 mm.Sensitivity experiments without evaporation of rainwater show that the convective cold pool plays an important role in the organization of the back-building process in the current extreme precipitation case.
基金supported in part by the National Key R&D Program of China(No.2021YFB2011300)the National Natural Science Foundation of China(No.52075262,51905271,52275062)+1 种基金the Fok Ying-Tong Education Foundation of China(No.171044)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX22_0471)。
文摘This article focuses on asymptotic precision motion control for electro-hydraulic axis systems under unknown time-variant parameters,mismatched and matched disturbances.Different from the traditional adaptive results that are applied to dispose of unknown constant parameters only,the unique feature is that an adaptive-gain nonlinear term is introduced into the control design to handle unknown time-variant parameters.Concurrently both mismatched and matched disturbances existing in electro-hydraulic axis systems can also be addressed in this way.With skillful integration of the backstepping technique and the adaptive control,a synthesized controller framework is successfully developed for electro-hydraulic axis systems,in which the coupled interaction between parameter estimation and disturbance estimation is avoided.Accordingly,this designed controller has the capacity of low-computation costs and simpler parameter tuning when compared to the other ones that integrate the adaptive control and observer/estimator-based technique to dividually handle parameter uncertainties and disturbances.Also,a nonlinear filter is designed to eliminate the“explosion of complexity”issue existing in the classical back-stepping technique.The stability analysis uncovers that all the closed-loop signals are bounded and the asymptotic tracking performance is also assured.Finally,contrastive experiment results validate the superiority of the developed method as well.
基金supported in part by the National Natural Science Foundation of China(Nos.U20B2054,U20B2056 and 62103275)the Natural Science Foundation of Shanghai,China(No.23ZR1432400)。
文摘In this paper,for Multi-Spacecraft System(MSS)with a directed communication topology link and a static virtual leader,a controller is proposed to realize attitude consensus and attitude stabilization with stochastic links failure and actuator saturation.First,an MSS attitude error model suitable for a directed topology link and with a static virtual leader based on SO(3)is derived,which considers that the attitude error on SO(3)cannot be defined based on algebraic subtraction.Then,we design a controller to realize the MSS on SO(3)with attitude consensus and attitude stabilization under stochastic links failure and actuator saturation.Finally,the simulation results of a multi-spacecraft system with stochastic links failure and a static virtual leader spacecraft are demonstrated to illustrate the efficiency of the attitude controller.
基金supported by the National Natural Science Foundation of China(12071409)。
文摘In this short paper,we remove the restrictionγ∈(1,3]that was used in the paper"The rate of convergence of the viscosity method for a nonlinear hyperbolic system"(Nonlinear Analysis,1999,38:435-445)and obtain a global Holder continuous solution and the convergent rate of the viscosity method for the Cauchy problem of the variant nonisentropic system of polytropic gas for any adiabatic exponentγ>1.
基金supported by the National Key R&D Program of China(No.2018YFA0703800)the Natural Science Foundation of China(No.T2293770)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA27000000)the National Science Foundation of Shandong Province(No.ZR2020ZD26).
文摘In this paper,we investigate the distributed estimation problem of continuous-time stochastic dynamic systems over sensor networks when both the system order and parameters are unknown.We propose a local information criterion(LIC)based on the L_(0)penalty term.By minimizing LIC at the diffusion time instant and utilizing the continuous-time diffusion least squares algorithm,we obtain a distributed estimation algorithm to simultaneously estimate the unknown order and the parameters of the system.By dealing with the effect of the system noises and the coupling relationship between estimation of system orders and parameters,we establish the almost sure convergence results of the proposed distributed estimation algorithm.Furthermore,we give a simulation example to verify the effectiveness of the distributed algorithm in estimating the system order and parameters.
基金Supported by the National Natural Science of China(U22B6002)National Natural Science Foundation of China(U2344209)Major Science and Technology Project of PetroChina(2023ZZ02)。
文摘Based on the“unidirectional break-up and convergence”geodynamic model,this study investigates the impact of the evolution of the Tethyan domain on the formation of petroleum systems in the Sichuan super basin and explores the enrichment pattern of natural gas.The results show that,firstly,the Sichuan Basin and its surrounding areas have experienced two unidirectional rifting-aggregation cycles triggered by the Proto-Tethys Ocean and the Paleo-Tethys Ocean during the Neoproterozoic to Triassic.During Jurassic–Cenozoic,the Sichuan Basin is incorporated in the circum-Tibetan plateau basin-mountain coupled tectonic domain system.The episodic tectonic movements within the plate control the sedimentary infill styles.Second,the evolution of the Tethyan domain,paleoclimatic environment and major geological events controlled the formation and distribution of high-quality source rocks within the basin.The rift valley and intracratonic rift,passive continental margin slope,and intracratonic sags are favorable areas for the development of source rocks.Third,the evolution of the Tethyan domain,supercontinent cycles,global sea level changes,and tectono-climatic events controlled the distribution of carbonate platform and reservoir-caprock combinations.The cratonic platform margins and sub-platform internal high terrains are key areas for finding carbonate high-energy facies belts.Syndepositional paleo-uplifts and surrounding slopes,regional unconformities,and later faults zone are areas where large-scale carbonate reservoirs are distributed.The regional evaporite or shale caprock are beneficial for the large-scale preservation of oil and gas in the basin.Fourth,the spatio-temporal matching relationship of reservoir forming factors influenced by the early tectonic-sedimentary evolution pattern and the degree of later tectonic modification is the key to oil and gas enrichment.Future oil and gas exploration should focus on potential gas systems during the Sinian rift period,Cambrian pre-salt gas systems in the eastern and southern Sichuan,as well as whole oil and gas systems of Permian and Triassic.
文摘AIM:To determine the smartphone use patterns and effects of smartphone use on accommodation and convergence system of the eyes among Malaysian teenagers.METHODS:A total of 62 participants aged between 13 and 17y were involved.A self-administered questionnaires containing 12 items was used to evaluate the smartphone usage patterns.This was followed by an eye examination,involving a battery of accommodation and convergence assessments before and after the smartphone use.The data analysis comprised descriptive statistics,paired t-test,and correlation coefficients.RESULTS:The use of smartphones is at a high level and at an optimal distance daily,with more than 6h a day watching video films,games,and completing school projects.Majority of the participants not reported eye strain factors and eye prescription changes with the use of digital devices.The use of a smartphone continuously for 30min was found to significantly decrease amplitude of accommodation,accommodative facility,and positive relative accommodation(P<0.001).Meanwhile,the lag of accommodation parameters and negative relative accommodation increased with the use of smartphones significantly(P<0.001).The near point of convergence(NPC)and distance and near negative fusional vergence decreased significantly(P<0.001).The NPC parameter was found to have a weak negative association with the frequency of smartphone use(R=-0.276,P<0.05).CONCLUSION:Frequent and continuous use of smartphones have increased visual stress and resulted in weakness of accommodation and vergence functions.Therefore,frequent break is mandatory when using a smartphone and appropriate visual hygiene,the 20-20-20 rule(every 20min,view something 20 feet away for 20s)are required during smartphone use to maintain visual function.
基金Supported by National Nature Science Foundation(12371381)Nature Science Foundation of Shanxi(202403021222270)。
文摘In this paper,we established a class of parallel algorithm for solving low-rank tensor completion problem.The main idea is that N singular value decompositions are implemented in N different processors for each slice matrix under unfold operator,and then the fold operator is used to form the next iteration tensor such that the computing time can be decreased.In theory,we analyze the global convergence of the algorithm.In numerical experiment,the simulation data and real image inpainting are carried out.Experiment results show the parallel algorithm outperform its original algorithm in CPU times under the same precision.
基金supported by the PhD Research Startup Foundation of Hubei University of Economics(Grand No.XJ23BS42).
文摘This paper studies the Smoluchowski–Kramers approximation for a discrete-time dynamical system modeled as the motion of a particle in a force field.We show that the approximation holds for the drift-implicit Euler–Maruyama discretization and derive its convergence rate.In particular,the solution of the discretized system converges to the solution of the first-order limit equation in the mean-square sense,and this convergence is independent of the order in which the mass parameterμand the step size h tend to zero.
基金Supported by the Science and Technology Project of Guangxi(Guike AD23023002)。
文摘In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradient method.Under the condition of standard Wolfe line search,the proposed search direction is the descent direction.For general nonlinear functions,the method is globally convergent.Finally,numerical results show that the proposed method is efficient.
文摘This paper presents an investigation on the target-guided coordinated control(TACC)of unmanned surface vehicles(USVs).In the scenario of tracking non-cooperative targets,the status information of the target can only be obtained by some USVs.In order to achieve semi-encirclement tracking of noncooperative targets under maritime security conditions,a fixed-time tracking control method based on dynamic surface control(DSC)is proposed in this paper.Firstly,a novel TACC architecture with decoupled kinematic control law and decoupled kinetic control law was designed to reduce the complexity of control system design.Secondly,the proposed DSC-based target-guided kinematic control law including tracking points pre-allocation strategy and sigmoid artificial potential functions(SigAPFs)can avoid collisions during tracking process and optimize kinematic control output.Finally,a fixed-time TACC system was proposed to achieve fast convergence of kinematic and kinetics errors.The effectiveness of the proposed TACC approach in improving target tracking safety and reducing control output chattering was verified by simulation comparison results.
基金Supported by NSFC (No.12371378)NSF of Fujian Province (Nos.2024J01980,2023J01955)。
文摘Analysis and design of linear periodic control systems are closely related to the periodic matrix equations.The biconjugate residual method(BCR for short)have been introduced by Vespucci and Broyden for efficiently solving linear systems Aα=b.The objective of this paper is to provide one new iterative algorithm based on BCR method to find the symmetric periodic solutions of linear periodic matrix equations.This kind of periodic matrix equations has not been dealt with yet.This iterative method is guaranteed to converge in a finite number of steps in the absence of round-off errors.Some numerical results are performed to illustrate the efficiency and feasibility of new method.
基金supported by Doctoral Scientific Research Starting Foundation of Jingdezhen Ceramic University(Grant No.102/01003002031)Re-accompanying Funding Project of Academic Achievements of Jingdezhen Ceramic University(Grant Nos.215/20506277,215/20506341)。
文摘The complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space is studied.By moment inequality and truncation methods,we establish the equivalent conditions of complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space.The results complement the corresponding results in probability space to those for sequences of independent,identically distributed random variables under sublinear expectation space.
