To enhance the comprehensive performance of artillery internal ballistics—encompassing power,accuracy,and service life—this study proposed a multi-stage multidisciplinary design optimization(MS-MDO)method.First,the ...To enhance the comprehensive performance of artillery internal ballistics—encompassing power,accuracy,and service life—this study proposed a multi-stage multidisciplinary design optimization(MS-MDO)method.First,the comprehensive artillery internal ballistic dynamics(AIBD)model,based on propellant combustion,rotation band engraving,projectile axial motion,and rifling wear models,was established and validated.This model was systematically decomposed into subsystems from a system engineering perspective.The study then detailed the MS-MDO methodology,which included Stage I(MDO stage)employing an improved collaborative optimization method for consistent design variables,and Stage II(Performance Optimization)focusing on the independent optimization of local design variables and performance metrics.The methodology was applied to the AIBD problem.Results demonstrated that the MS-MDO method in Stage I effectively reduced iteration and evaluation counts,thereby accelerating system-level convergence.Meanwhile,Stage II optimization markedly enhanced overall performance.These comprehensive evaluation results affirmed the effectiveness of the MS-MDO method.展开更多
To address the scheduling problem involving energy storage systems and uncertain energy,we propose a method based on multi-stage robust optimization.This approach aims to regulate the energy storage system by using a ...To address the scheduling problem involving energy storage systems and uncertain energy,we propose a method based on multi-stage robust optimization.This approach aims to regulate the energy storage system by using a multi-stage robust optimal control method,which helps overcome the limitations of traditional methods in terms of time scale.The goal is to effectively utilize the energy storage power station system to address issues caused by unpredictable variations in environmental energy and fluctuating load throughout the day.To achieve this,a mathematical model is constructed to represent uncertain energy sources such as photovoltaic and wind power.The generalized Benders Decomposition method is then employed to solve the multi-stage objective optimization problem.By decomposing the problem into a series of sub-objectives,the system scale is effectively reduced,and the algorithm’s convergence ability is improved.Compared with other algorithms,the multi-stage robust optimization model has better economy and convergence ability and can be used to guide the power dispatching of uncertain energy and energy storage systems.展开更多
Gneisses with anatectic characteristics from the Liansan island in the Sulu UHPM(ultra-high pressure metamorphic)belt were studied for petrography,titanite U-Pb dating and mineral geochemistry.Three origins of garnets...Gneisses with anatectic characteristics from the Liansan island in the Sulu UHPM(ultra-high pressure metamorphic)belt were studied for petrography,titanite U-Pb dating and mineral geochemistry.Three origins of garnets are distinguished:metamorphic garnet,peritectic garnet and anatectic garnet,which are formed in the stages of peak metamorphism,retrograde anatexis and melt crystallization,respectively.The euhedral titanite has a high content of REE and high Th/U ratios,which is interpreted as indicating that it was newly-formed from an anatectic melt.The LA-ICP-MS titanite U-Pb dating yields 214-217 Ma ages for the titanite(melt)crystallization.The distribution of trace elements varies in response to the different host minerals at different stages.At the peak metamorphic stage,Y and HREE are mainly hosted by garnet,Ba and Rb by phengite,Sr,Nb,Ta,Pb,Th,U and LREE by allanite and Y,U and HREE by zircon.During partial melting,Y,Pb,Th,U and REE are released into the melt,which causes a dramatic decline of these element contents in the retrograde minerals.Finally,titanite absorbs most of the Nb,U,LREE and HREE from the melt.Therefore,the different stages of metamorphism have different mineral assemblages,which host different trace elements.展开更多
To reduce the carbon footprint in the transportation sector and improve overall vehicle efficiency,a large number of electric vehicles are being manufactured.This is due to the fact that environmental concerns and the...To reduce the carbon footprint in the transportation sector and improve overall vehicle efficiency,a large number of electric vehicles are being manufactured.This is due to the fact that environmental concerns and the depletion of fossil fuels have become significant global problems.Lithium-ion batteries(LIBs)have been distinguished themselves from alternative energy storage technologies for electric vehicles(EVs) due to superior qualities like high energy and power density,extended cycle life,and low maintenance cost to a competitive price.However,there are still certain challenges to be solved,like EV fast charging,longer lifetime,and reduced weight.For fast charging,the multi-stage constant current(MSCC) charging technique is an emerging solution to improve charging efficiency,reduce temperature rise during charging,increase charging/discharging capacities,shorten charging time,and extend the cycle life.However,there are large variations in the implementation of the number of stages,stage transition criterion,and C-rate selection for each stage.This paper provides a review of these problems by compiling information from the literature.An overview of the impact of different design parameters(number of stages,stage transition,and C-rate) that the MSCC charging techniques have had on the LIB performance and cycle life is described in detail and analyzed.The impact of design parameters on lifetime,charging efficiency,charging and discharging capacity,charging speed,and rising temperature during charging is presented,and this review provides guidelines for designing advanced fast charging strategies and determining future research gaps.展开更多
The metaheuristic algorithms are widely used in solving the parameters of the optimization problem.The marine predators algorithm(MPA)is a novel population-based intelligent algorithm.Although MPA has shown a talented...The metaheuristic algorithms are widely used in solving the parameters of the optimization problem.The marine predators algorithm(MPA)is a novel population-based intelligent algorithm.Although MPA has shown a talented foraging strategy,it still needs a balance of exploration and exploitation.Therefore,a multi-stage improvement of marine predators algorithm(MSMPA)is proposed in this paper.The algorithm retains the advantage of multistage search and introduces a linear flight strategy in the middle stage to enhance the interaction between predators.Predators further away from the historical optimum are required to move,increasing the exploration capability of the algorithm.In the middle and late stages,the searchmechanism of particle swarmoptimization(PSO)is inserted,which enhances the exploitation capability of the algorithm.This means that the stochasticity is decreased,that is the optimal region where predators jumping out is effectively stifled.At the same time,self-adjusting weight is used to regulate the convergence speed of the algorithm,which can balance the exploration and exploitation capability of the algorithm.The algorithm is applied to different types of CEC2017 benchmark test functions and threemultidimensional nonlinear structure design optimization problems,compared with other recent algorithms.The results show that the convergence speed and accuracy of MSMPA are significantly better than that of the comparison algorithms.展开更多
DEAR EDITOR,Big cats,such as Amur tigers(Panthera tigris altaica)and Amur leopards(P.pardus orientalis),are apex predator and have evolved specialized traits for hunting and carnivory(Moya et al.,2022),thus playing a ...DEAR EDITOR,Big cats,such as Amur tigers(Panthera tigris altaica)and Amur leopards(P.pardus orientalis),are apex predator and have evolved specialized traits for hunting and carnivory(Moya et al.,2022),thus playing a crucial role in maintaining biodiversity and ecosystem integrity by regulating prey-predator dynamics.However,human-induced pressures,habitat fragmentation,and environmental alterations have restricted these species in small and isolated populations.Currently,all extant big cats are categorized as endangered or threatened according to their conservation status.Amur tigers and Amur leopards share overlapping geographic ranges,habitats,and certain prey species in the forests of Northeast Asia(Jiang et al.,2015).To reduce interspecies conflict,these carnivores exhibit differentiated dietary and temporal niches.Amur tigers predominantly prey on large ungulates,while Amur leopards hunt small to medium-sized animals(Sugimoto et al.,2016).Additionally,they occupy different temporal niches,with tigers being active at night and leopards more active during the day.Despite spatial and temporal niche partitioning,interspecific competition between these two species is inevitable.Tigers,benefiting from their greater size,have a competitive advantage over leopards,which can manifest in occasional leopard predation by tigers and declines in leopard populations with increasing tiger density(Jiang et al.,2015).Tigers also displace leopards from marginal habitats in nature reserves where they coexist.展开更多
The construction of a new beamline,BL10U1,was completed at the Shanghai synchrotron radiation facility in 2020.This multipurpose beamline was designed to provide X-ray scattering techniques such as ultra-small-angle X...The construction of a new beamline,BL10U1,was completed at the Shanghai synchrotron radiation facility in 2020.This multipurpose beamline was designed to provide X-ray scattering techniques such as ultra-small-angle X-ray scattering(USAXS),small-angle X-ray scattering(SAXS),wide-angle X-ray scattering,and microfocus SAXS(μSAXS)for a broad user community.To realize fast time-resolved USAXS experiments,the beamline adopted an in-vacuum undulator with a total length of 1.6 m as the photon source.An in-house cryogenic-cooled double multilayer monochromator was installed to deliver a photon flux of approximately 10^(13) photons/s at a photon energy of 10 keV.The three-year successful operation of this beamline demonstrated that the monochromator operated smoothly,as expected.BL10U1 has three end stations in succession:USAXS end station,μSAXS end station,and end station for industrial applications.The minimum scattering vector q~0.0042 nm^(-1) at 10 keV can be achieved at the USAXS end station equipped with a 28 m-long and 1.8 m-diameter vacuum flight tube.At theμSAXS end station,a beam spot of less than 10×8μm was achieved for micro-SAXS experiments.In contrast,in situ experimental instruments up to 5 m high and 8 m wide can be mounted at the industrial application end station,which offers industrial scientists the opportunity to use their large industrial equipment.BL10U1 opens up a new capability to investigate phenomena such as non-equilibrium and dynamic processes of materials with a wide length scale from angstroms to micrometers with millisecond time resolution.In this paper,we also report beamline design considerations and commissioning results.展开更多
Fluid-structure-particle interactions in three spatial dimensions happen in many environmental and engineering flows.This paper presents the parallel algorithms for the hybrid diffuse and sharp interface immersed boun...Fluid-structure-particle interactions in three spatial dimensions happen in many environmental and engineering flows.This paper presents the parallel algorithms for the hybrid diffuse and sharp interface immersed boundary(IB)method developed in our previous work.For the moving structure modeled using the sharp interface IB method,a recursive box method is developed for efficiently classifying the background grid nodes.For the particles modeled using the diffuse interface IB method,a‘master-slave’approach is adopted.For the particle-particle interaction(PPI)and particle-structure interaction(PSI),a fast algorithm for classifying the active and inactive Lagrangian points,which discretize the particle surface,is developed for the‘dry’contact approach.The results show that the proposed recursive box method can reduce the classifying time from 52seconds to 0.3 seconds.Acceptable parallel efficiency is obtained for cases with different particle concentrations.Furthermore,the lubrication model is utilized when a particle approaches a wall,enabling an accurate simulation of the rebounding phenomena in the benchmark particle-wall collision problem.At last,the capability of the proposed computational framework is demonstrated by simulating particle-laden turbulent channel flows with rough walls.展开更多
Background:To systematically evaluate the efficacy and safety of activating blood and resolving stasis in patients with IgA nephropathy.Methods:From inception to May 2022,databases including PubMed,Embase,the Cochrane...Background:To systematically evaluate the efficacy and safety of activating blood and resolving stasis in patients with IgA nephropathy.Methods:From inception to May 2022,databases including PubMed,Embase,the Cochrane Library,Web of Science,WanFang database,Chinese Biomedical Database,VIP,and China National Knowledge Infrastructure were searched for randomized controlled trials about enhancing blood circulation and removing stasis for IgA nephropathy.For the articles that satisfied the requirements,quality assessment and meta-analysis were done.Results:Seventeen randomized controlled trials with a total of 1653 patients were included.Meta-analysis showed that activating blood and resolving stasis could increase therapeutic effectiveness(risk ratio(RR)=-0.47,95%confidence interval(CI)(-0.37,-0.2),P=0.0006)and decrease levels of serum creatinine(RR=-0.47,95%CI(-0.37,-0.2),P=0.0006),urea nitrogen(RR=0.85,95%CI(1.44,0.26),P=0.005),24-hour urinary protein quantification(RR=1.6,95%CI(2.44,0.95).P=0.00001),and urine red blood cell count(RR=1.7,95%CI(2.57,0.82),P=0.0001).There was no significant difference between the two groups in terms of security(RR=0.6,95%CI(0.36,1.01),P=0.05).Conclusion:Western medicine combined activating blood and resolving stasis is more efficient than Western medicine therapy alone in treating IgA nephropathy,but it still needs to be supported by additional large-scale,multi-center randomized controlled clinical trials due to the poor quality of the included trials.展开更多
The mechanical behavior and microstructures of an Al-Zn-Mg-Cu-Cr aluminum alloy during multi-stage hot deformation were investigated by thermal stimulation test, optical microscopy, and transmission electron microscop...The mechanical behavior and microstructures of an Al-Zn-Mg-Cu-Cr aluminum alloy during multi-stage hot deformation were investigated by thermal stimulation test, optical microscopy, and transmission electron microscopy. The true stress vs true strain curves and the microstructure evolution of two hot deformation procedures were gained. The flow stress of the alloy studied decreases with increasing the deforming passes and declining the temperature, and the larger the temperature decline between adjacent stages, the larger the peak stress fall is. The stress-strain behavior mainly result from the dynamic recovery during deformation, the static recovery and recrystallization in the delay time, and the second phases precipitated from the matrix at high temperature.展开更多
Springback of a SUS321 complex geometry part formed by the multi-stage rigid-flexible compound process was studied through numerical simulations and laboratory experiments in this work.The sensitivity analysis was pro...Springback of a SUS321 complex geometry part formed by the multi-stage rigid-flexible compound process was studied through numerical simulations and laboratory experiments in this work.The sensitivity analysis was provided to have an insight in the effect of the evaluated process parameters.Furthermore,in order to minimize the springback problem,an accurate springback simulation model of the part was established and validated.The effects of the element size and timesteps on springback model were further investigated.Results indicate that the custom mesh size is beneficial for the springback simulation,and the four timesteps are found suited for the springback analysis for the complex geometry part.Finally,a strategy for reducing the springback by changing the geometry of the blank is proposed.The optimal blank geometry is obtained and used for manufacturing the part.展开更多
A multi-stage influence diagram is used to model the pilot's sequential decision making in one on one air combat. The model based on the multi-stage influence diagram graphically describes the elements of decision pr...A multi-stage influence diagram is used to model the pilot's sequential decision making in one on one air combat. The model based on the multi-stage influence diagram graphically describes the elements of decision process, and contains a point-mass model for the dynamics of an aircraft and takes into account the decision maker's preferences under uncertain conditions. Considering an active opponent, the opponent's maneuvers can be modeled stochastically. The solution of multistage influence diagram can be obtained by converting the multistage influence diagram into a two-level optimization problem. The simulation results show the model is effective.展开更多
Duplex-structured TC21 alloy samples were first solution-treated at a higher temperature in theα+βregion(940°C)with furnace cooling(FC),air cooling(AC),and water cooling(WC),followed by a second-stage solution ...Duplex-structured TC21 alloy samples were first solution-treated at a higher temperature in theα+βregion(940°C)with furnace cooling(FC),air cooling(AC),and water cooling(WC),followed by a second-stage solution treatment at a lower temperature in theα+βregion(900°C),and then finally aged at 590°C.The effects of the morphology and quantity ofαphases on the structure and properties of the TC21 alloy after the different heat treatments were analyzed.The in-situ tensile deformation process and crack propagation behavior were observed using scanning electron microscopy(SEM).The quantity of equiaxedαphases as well as the thickness of lamellarαphases reduced,the tensile strength increased firstly and then decreased,the elongation decreased with the increasing cooling rate after the first-stage solution treatment.The amount and size of lamellarαphases increased after the second-stage solution treatment because of sufficient diffusion of the alloying elements,thereby leading to increased tensile strength.The amount of dispersedαphases increased after the third-stage aging treatment owing to the increase in the nucleation rate,resulting in a noteworthy strengthening effect.After the third-stage aging treatment,the first-stage FC sample exhibited better mechanical properties because it contained more equiaxedαandβtrans phases than the first-stage AC and WC samples.展开更多
UAV-assisted D2D networks can provide auxiliary communication for areas with poor communication facilities by using the characteristics of easy deployment of unmanned aerial vehicle(UAV),then it becomes a promising te...UAV-assisted D2D networks can provide auxiliary communication for areas with poor communication facilities by using the characteristics of easy deployment of unmanned aerial vehicle(UAV),then it becomes a promising technology.However,the coexistence of UAV and D2D aggravates the conflict of spectrum resources.In addition,when the UAV performs the communication service,it will inevitably cause the location change,which will make the original channel allocation no longer applicable.Inspired by the influence of frequent channel switching on channel allocation,we define the communication utility as a tradeoff between the throughput and channel switching cost.In the considered model,we investigate the multi-stage hierarchical spectrum access problem with maximizing aggregate communication utilities in UAV-assisted D2D networks.In particular,due to the hierarchical feature of the considered network,we adopt Stackelberg game to formulate this spectrum access problem where both the throughput and channel switching cost are considered.We prove that the proposed game has a stable Stackelberg equilibrium(SE),and the heterogeneous network based channel allocation(HN-CA)algorithm is proposed to achieve the desired solution.Simulation results verify the validity of the proposed game and show the effectiveness of the HN-CA algorithm.展开更多
A 22-stage 4 MV laser-triggered multistage multi-channel switch (LTS) was designed according to the hypothesis that the well-proportioned electrical field distribution is helpful in reducing the jitter of delay. Fie...A 22-stage 4 MV laser-triggered multistage multi-channel switch (LTS) was designed according to the hypothesis that the well-proportioned electrical field distribution is helpful in reducing the jitter of delay. Field distribution in the switch section is regulated by a metal field regulation ring and several gradient rings. In order to reduce the jitter further, a SFB/N2 mixture is chosen as the switching medium. The generalized standard deviation of the self-breakdown voltage and the deviation of the average value from the prediction is less than 4.4% and 13% respectively. Linearity of the self-breakdown voltage is better than 0.95. Triggered by a laser pulse of 35 mJ/3 ns, the delay is about 26 ns at a working voltage of 85±3% USB (Self-breakdown Voltage). Maximum deviation of delay is less than =t=2.5 ns. Jitter is less than 1.5 ns. The delay and jitter decrease with the increase in the working ratio (the ratio of working voltage to USB), pressure or voltage.展开更多
In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper (MSPMD) is investigated. Special attention is given to overcoming space limita...In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper (MSPMD) is investigated. Special attention is given to overcoming space limitations for installing the control device in the tower and the effect of varying natural frequency of the towers during construction. First, the finite element model of the bridge during its construction and the basic equation of motion of the MSPMD are introduced. The equation of motion of the bridge with the MSPMD under along-wind excitation is then established. Finally, a numerical simulation and parametric study are conducted to assess the effectiveness of the control system for reducing the wind-induced vibration of the bridge towers during construction. The numerical simulation results show that the MSPMD is practical and effective for reducing the along-wind response of the single column tower, can be installed in a small area of the tower, and complies with the time-variant characteristics of the bridge during its entire construction stage.展开更多
Nowadays, security defence of network uses the game theory, which mostly applies complete information game model or even the static game model. To get closer to the actual network and defend actively, we propose a net...Nowadays, security defence of network uses the game theory, which mostly applies complete information game model or even the static game model. To get closer to the actual network and defend actively, we propose a network attack-defence game model by using signalling game, which is modelled in the way of dynamic and incomplete information. We improve the traditional attack-defence strategies quantization method to meet the needs of the network signalling game model. Moreover, we give the calculation of the game equilibrium and analyse the optimal defence scheme. Finally, we analyse and verify effectiveness of the model and method through a simulation experiment.展开更多
The possibility of using a multi-stage pendulum mass damper (MSPMD) to control wind-induced vibration of a single column tower of a cable-stayed bridge during construction was studied theoretically in part I of this...The possibility of using a multi-stage pendulum mass damper (MSPMD) to control wind-induced vibration of a single column tower of a cable-stayed bridge during construction was studied theoretically in part I of this work. In this paper, the performance of the MSPMD for reducing bridge tower vibration is studied experimentally. A MSPMD model and a tower model of the bridge with geometry scaling of 1:100 were designed and manufactured. Calibration of the MSPMD model with different wire lengths is conducted to verify the analytical model of the damper. A series of tests for the uncontrolled freestanding tower, tower with cables, and tower with MSPMD model are then performed under harmonic and white noise excitations. The experimental results show that the responses of the tower model significantly decrease with the installation of the MSPMD model, which demonstrates the effectiveness of the M SPMD to mitigate the vibration of the bridge tower.展开更多
基金supported by the“National Natural Science Foundation of China”(Grant Nos.52105106,52305155)the“Jiangsu Province Natural Science Foundation”(Grant Nos.BK20210342,BK20230904)the“Young Elite Scientists Sponsorship Programby CAST”(Grant No.2023JCJQQT061).
文摘To enhance the comprehensive performance of artillery internal ballistics—encompassing power,accuracy,and service life—this study proposed a multi-stage multidisciplinary design optimization(MS-MDO)method.First,the comprehensive artillery internal ballistic dynamics(AIBD)model,based on propellant combustion,rotation band engraving,projectile axial motion,and rifling wear models,was established and validated.This model was systematically decomposed into subsystems from a system engineering perspective.The study then detailed the MS-MDO methodology,which included Stage I(MDO stage)employing an improved collaborative optimization method for consistent design variables,and Stage II(Performance Optimization)focusing on the independent optimization of local design variables and performance metrics.The methodology was applied to the AIBD problem.Results demonstrated that the MS-MDO method in Stage I effectively reduced iteration and evaluation counts,thereby accelerating system-level convergence.Meanwhile,Stage II optimization markedly enhanced overall performance.These comprehensive evaluation results affirmed the effectiveness of the MS-MDO method.
文摘To address the scheduling problem involving energy storage systems and uncertain energy,we propose a method based on multi-stage robust optimization.This approach aims to regulate the energy storage system by using a multi-stage robust optimal control method,which helps overcome the limitations of traditional methods in terms of time scale.The goal is to effectively utilize the energy storage power station system to address issues caused by unpredictable variations in environmental energy and fluctuating load throughout the day.To achieve this,a mathematical model is constructed to represent uncertain energy sources such as photovoltaic and wind power.The generalized Benders Decomposition method is then employed to solve the multi-stage objective optimization problem.By decomposing the problem into a series of sub-objectives,the system scale is effectively reduced,and the algorithm’s convergence ability is improved.Compared with other algorithms,the multi-stage robust optimization model has better economy and convergence ability and can be used to guide the power dispatching of uncertain energy and energy storage systems.
基金supported by funds from the National Natural Science Foundation of China(Grant Nos.42172067,41972064,U1906207)the SDUST Research Fund。
文摘Gneisses with anatectic characteristics from the Liansan island in the Sulu UHPM(ultra-high pressure metamorphic)belt were studied for petrography,titanite U-Pb dating and mineral geochemistry.Three origins of garnets are distinguished:metamorphic garnet,peritectic garnet and anatectic garnet,which are formed in the stages of peak metamorphism,retrograde anatexis and melt crystallization,respectively.The euhedral titanite has a high content of REE and high Th/U ratios,which is interpreted as indicating that it was newly-formed from an anatectic melt.The LA-ICP-MS titanite U-Pb dating yields 214-217 Ma ages for the titanite(melt)crystallization.The distribution of trace elements varies in response to the different host minerals at different stages.At the peak metamorphic stage,Y and HREE are mainly hosted by garnet,Ba and Rb by phengite,Sr,Nb,Ta,Pb,Th,U and LREE by allanite and Y,U and HREE by zircon.During partial melting,Y,Pb,Th,U and REE are released into the melt,which causes a dramatic decline of these element contents in the retrograde minerals.Finally,titanite absorbs most of the Nb,U,LREE and HREE from the melt.Therefore,the different stages of metamorphism have different mineral assemblages,which host different trace elements.
文摘To reduce the carbon footprint in the transportation sector and improve overall vehicle efficiency,a large number of electric vehicles are being manufactured.This is due to the fact that environmental concerns and the depletion of fossil fuels have become significant global problems.Lithium-ion batteries(LIBs)have been distinguished themselves from alternative energy storage technologies for electric vehicles(EVs) due to superior qualities like high energy and power density,extended cycle life,and low maintenance cost to a competitive price.However,there are still certain challenges to be solved,like EV fast charging,longer lifetime,and reduced weight.For fast charging,the multi-stage constant current(MSCC) charging technique is an emerging solution to improve charging efficiency,reduce temperature rise during charging,increase charging/discharging capacities,shorten charging time,and extend the cycle life.However,there are large variations in the implementation of the number of stages,stage transition criterion,and C-rate selection for each stage.This paper provides a review of these problems by compiling information from the literature.An overview of the impact of different design parameters(number of stages,stage transition,and C-rate) that the MSCC charging techniques have had on the LIB performance and cycle life is described in detail and analyzed.The impact of design parameters on lifetime,charging efficiency,charging and discharging capacity,charging speed,and rising temperature during charging is presented,and this review provides guidelines for designing advanced fast charging strategies and determining future research gaps.
基金supported in part byNationalNatural Science Foundation of China(No.62066001)Natural Science Foundation of Ningxia Province(No.2021AAC03230)Program of Graduate Innovation Research of North Minzu University(No.YCX22111).
文摘The metaheuristic algorithms are widely used in solving the parameters of the optimization problem.The marine predators algorithm(MPA)is a novel population-based intelligent algorithm.Although MPA has shown a talented foraging strategy,it still needs a balance of exploration and exploitation.Therefore,a multi-stage improvement of marine predators algorithm(MSMPA)is proposed in this paper.The algorithm retains the advantage of multistage search and introduces a linear flight strategy in the middle stage to enhance the interaction between predators.Predators further away from the historical optimum are required to move,increasing the exploration capability of the algorithm.In the middle and late stages,the searchmechanism of particle swarmoptimization(PSO)is inserted,which enhances the exploitation capability of the algorithm.This means that the stochasticity is decreased,that is the optimal region where predators jumping out is effectively stifled.At the same time,self-adjusting weight is used to regulate the convergence speed of the algorithm,which can balance the exploration and exploitation capability of the algorithm.The algorithm is applied to different types of CEC2017 benchmark test functions and threemultidimensional nonlinear structure design optimization problems,compared with other recent algorithms.The results show that the convergence speed and accuracy of MSMPA are significantly better than that of the comparison algorithms.
基金supported by the Fundamental Research Funds for the Central Universities of China(2572022DQ03)National Natural Science Foundation of China(32170517)+1 种基金Guangdong Provincial Key Laboratory of Genome Read and Write(2017B030301011)supported by China National GeneBank(CNGB)。
文摘DEAR EDITOR,Big cats,such as Amur tigers(Panthera tigris altaica)and Amur leopards(P.pardus orientalis),are apex predator and have evolved specialized traits for hunting and carnivory(Moya et al.,2022),thus playing a crucial role in maintaining biodiversity and ecosystem integrity by regulating prey-predator dynamics.However,human-induced pressures,habitat fragmentation,and environmental alterations have restricted these species in small and isolated populations.Currently,all extant big cats are categorized as endangered or threatened according to their conservation status.Amur tigers and Amur leopards share overlapping geographic ranges,habitats,and certain prey species in the forests of Northeast Asia(Jiang et al.,2015).To reduce interspecies conflict,these carnivores exhibit differentiated dietary and temporal niches.Amur tigers predominantly prey on large ungulates,while Amur leopards hunt small to medium-sized animals(Sugimoto et al.,2016).Additionally,they occupy different temporal niches,with tigers being active at night and leopards more active during the day.Despite spatial and temporal niche partitioning,interspecific competition between these two species is inevitable.Tigers,benefiting from their greater size,have a competitive advantage over leopards,which can manifest in occasional leopard predation by tigers and declines in leopard populations with increasing tiger density(Jiang et al.,2015).Tigers also displace leopards from marginal habitats in nature reserves where they coexist.
基金This work was supported by the National Key R&D Program of China(No.2020YFA0405802)the Shanghai Large Scientific Facilities Center.
文摘The construction of a new beamline,BL10U1,was completed at the Shanghai synchrotron radiation facility in 2020.This multipurpose beamline was designed to provide X-ray scattering techniques such as ultra-small-angle X-ray scattering(USAXS),small-angle X-ray scattering(SAXS),wide-angle X-ray scattering,and microfocus SAXS(μSAXS)for a broad user community.To realize fast time-resolved USAXS experiments,the beamline adopted an in-vacuum undulator with a total length of 1.6 m as the photon source.An in-house cryogenic-cooled double multilayer monochromator was installed to deliver a photon flux of approximately 10^(13) photons/s at a photon energy of 10 keV.The three-year successful operation of this beamline demonstrated that the monochromator operated smoothly,as expected.BL10U1 has three end stations in succession:USAXS end station,μSAXS end station,and end station for industrial applications.The minimum scattering vector q~0.0042 nm^(-1) at 10 keV can be achieved at the USAXS end station equipped with a 28 m-long and 1.8 m-diameter vacuum flight tube.At theμSAXS end station,a beam spot of less than 10×8μm was achieved for micro-SAXS experiments.In contrast,in situ experimental instruments up to 5 m high and 8 m wide can be mounted at the industrial application end station,which offers industrial scientists the opportunity to use their large industrial equipment.BL10U1 opens up a new capability to investigate phenomena such as non-equilibrium and dynamic processes of materials with a wide length scale from angstroms to micrometers with millisecond time resolution.In this paper,we also report beamline design considerations and commissioning results.
基金Project supported by the National Natural Science Foundation of China(Nos.12202456 and12172360)the Basic Science Center Program for“Multiscale Problems in Nonlinear Mechanics”of the National Natural Science Foundation of China(No.11988102)the China Postdoctoral Science Foundation(No.2021M693241)。
文摘Fluid-structure-particle interactions in three spatial dimensions happen in many environmental and engineering flows.This paper presents the parallel algorithms for the hybrid diffuse and sharp interface immersed boundary(IB)method developed in our previous work.For the moving structure modeled using the sharp interface IB method,a recursive box method is developed for efficiently classifying the background grid nodes.For the particles modeled using the diffuse interface IB method,a‘master-slave’approach is adopted.For the particle-particle interaction(PPI)and particle-structure interaction(PSI),a fast algorithm for classifying the active and inactive Lagrangian points,which discretize the particle surface,is developed for the‘dry’contact approach.The results show that the proposed recursive box method can reduce the classifying time from 52seconds to 0.3 seconds.Acceptable parallel efficiency is obtained for cases with different particle concentrations.Furthermore,the lubrication model is utilized when a particle approaches a wall,enabling an accurate simulation of the rebounding phenomena in the benchmark particle-wall collision problem.At last,the capability of the proposed computational framework is demonstrated by simulating particle-laden turbulent channel flows with rough walls.
文摘Background:To systematically evaluate the efficacy and safety of activating blood and resolving stasis in patients with IgA nephropathy.Methods:From inception to May 2022,databases including PubMed,Embase,the Cochrane Library,Web of Science,WanFang database,Chinese Biomedical Database,VIP,and China National Knowledge Infrastructure were searched for randomized controlled trials about enhancing blood circulation and removing stasis for IgA nephropathy.For the articles that satisfied the requirements,quality assessment and meta-analysis were done.Results:Seventeen randomized controlled trials with a total of 1653 patients were included.Meta-analysis showed that activating blood and resolving stasis could increase therapeutic effectiveness(risk ratio(RR)=-0.47,95%confidence interval(CI)(-0.37,-0.2),P=0.0006)and decrease levels of serum creatinine(RR=-0.47,95%CI(-0.37,-0.2),P=0.0006),urea nitrogen(RR=0.85,95%CI(1.44,0.26),P=0.005),24-hour urinary protein quantification(RR=1.6,95%CI(2.44,0.95).P=0.00001),and urine red blood cell count(RR=1.7,95%CI(2.57,0.82),P=0.0001).There was no significant difference between the two groups in terms of security(RR=0.6,95%CI(0.36,1.01),P=0.05).Conclusion:Western medicine combined activating blood and resolving stasis is more efficient than Western medicine therapy alone in treating IgA nephropathy,but it still needs to be supported by additional large-scale,multi-center randomized controlled clinical trials due to the poor quality of the included trials.
基金supported by the National Key Basic Research and Development Program of China(No.G1999064908)
文摘The mechanical behavior and microstructures of an Al-Zn-Mg-Cu-Cr aluminum alloy during multi-stage hot deformation were investigated by thermal stimulation test, optical microscopy, and transmission electron microscopy. The true stress vs true strain curves and the microstructure evolution of two hot deformation procedures were gained. The flow stress of the alloy studied decreases with increasing the deforming passes and declining the temperature, and the larger the temperature decline between adjacent stages, the larger the peak stress fall is. The stress-strain behavior mainly result from the dynamic recovery during deformation, the static recovery and recrystallization in the delay time, and the second phases precipitated from the matrix at high temperature.
基金Project(2014ZX04002041)supported by the National Science and Technology Major Project,ChinaProject(51175024)supported by the National Natural Science Foundation of China
文摘Springback of a SUS321 complex geometry part formed by the multi-stage rigid-flexible compound process was studied through numerical simulations and laboratory experiments in this work.The sensitivity analysis was provided to have an insight in the effect of the evaluated process parameters.Furthermore,in order to minimize the springback problem,an accurate springback simulation model of the part was established and validated.The effects of the element size and timesteps on springback model were further investigated.Results indicate that the custom mesh size is beneficial for the springback simulation,and the four timesteps are found suited for the springback analysis for the complex geometry part.Finally,a strategy for reducing the springback by changing the geometry of the blank is proposed.The optimal blank geometry is obtained and used for manufacturing the part.
文摘A multi-stage influence diagram is used to model the pilot's sequential decision making in one on one air combat. The model based on the multi-stage influence diagram graphically describes the elements of decision process, and contains a point-mass model for the dynamics of an aircraft and takes into account the decision maker's preferences under uncertain conditions. Considering an active opponent, the opponent's maneuvers can be modeled stochastically. The solution of multistage influence diagram can be obtained by converting the multistage influence diagram into a two-level optimization problem. The simulation results show the model is effective.
基金This work was financially supported by the Guizhou Science and Technology Fund Project(Nos.[2018]1027,[2019]2165,and[2014]6013)the Engineering Research Center Project from Guizhou Provincial Education Department,China(No.[2017]016).
文摘Duplex-structured TC21 alloy samples were first solution-treated at a higher temperature in theα+βregion(940°C)with furnace cooling(FC),air cooling(AC),and water cooling(WC),followed by a second-stage solution treatment at a lower temperature in theα+βregion(900°C),and then finally aged at 590°C.The effects of the morphology and quantity ofαphases on the structure and properties of the TC21 alloy after the different heat treatments were analyzed.The in-situ tensile deformation process and crack propagation behavior were observed using scanning electron microscopy(SEM).The quantity of equiaxedαphases as well as the thickness of lamellarαphases reduced,the tensile strength increased firstly and then decreased,the elongation decreased with the increasing cooling rate after the first-stage solution treatment.The amount and size of lamellarαphases increased after the second-stage solution treatment because of sufficient diffusion of the alloying elements,thereby leading to increased tensile strength.The amount of dispersedαphases increased after the third-stage aging treatment owing to the increase in the nucleation rate,resulting in a noteworthy strengthening effect.After the third-stage aging treatment,the first-stage FC sample exhibited better mechanical properties because it contained more equiaxedαandβtrans phases than the first-stage AC and WC samples.
基金This work is supported by the Jiangsu Provincial Natural Science Fund for Outstanding Young Scholars(No.BK20180028)the Natural Science Foundations of China(No.61671474)+1 种基金the Jiangsu Provincial Natural Science Fund for Excellent Young Scholars(No.BK20170089)and in part by Postgraduate Research and Practice Innovation Program of Jiangsu Province under No.KYCX190188.
文摘UAV-assisted D2D networks can provide auxiliary communication for areas with poor communication facilities by using the characteristics of easy deployment of unmanned aerial vehicle(UAV),then it becomes a promising technology.However,the coexistence of UAV and D2D aggravates the conflict of spectrum resources.In addition,when the UAV performs the communication service,it will inevitably cause the location change,which will make the original channel allocation no longer applicable.Inspired by the influence of frequent channel switching on channel allocation,we define the communication utility as a tradeoff between the throughput and channel switching cost.In the considered model,we investigate the multi-stage hierarchical spectrum access problem with maximizing aggregate communication utilities in UAV-assisted D2D networks.In particular,due to the hierarchical feature of the considered network,we adopt Stackelberg game to formulate this spectrum access problem where both the throughput and channel switching cost are considered.We prove that the proposed game has a stable Stackelberg equilibrium(SE),and the heterogeneous network based channel allocation(HN-CA)algorithm is proposed to achieve the desired solution.Simulation results verify the validity of the proposed game and show the effectiveness of the HN-CA algorithm.
文摘A 22-stage 4 MV laser-triggered multistage multi-channel switch (LTS) was designed according to the hypothesis that the well-proportioned electrical field distribution is helpful in reducing the jitter of delay. Field distribution in the switch section is regulated by a metal field regulation ring and several gradient rings. In order to reduce the jitter further, a SFB/N2 mixture is chosen as the switching medium. The generalized standard deviation of the self-breakdown voltage and the deviation of the average value from the prediction is less than 4.4% and 13% respectively. Linearity of the self-breakdown voltage is better than 0.95. Triggered by a laser pulse of 35 mJ/3 ns, the delay is about 26 ns at a working voltage of 85±3% USB (Self-breakdown Voltage). Maximum deviation of delay is less than =t=2.5 ns. Jitter is less than 1.5 ns. The delay and jitter decrease with the increase in the working ratio (the ratio of working voltage to USB), pressure or voltage.
基金Area Strategic Development Program inStructural Control and Intelligent Building from The HongKong Polytechnic University, and National Natural SciencFoundation of China Under Grant No. 50408011
文摘In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper (MSPMD) is investigated. Special attention is given to overcoming space limitations for installing the control device in the tower and the effect of varying natural frequency of the towers during construction. First, the finite element model of the bridge during its construction and the basic equation of motion of the MSPMD are introduced. The equation of motion of the bridge with the MSPMD under along-wind excitation is then established. Finally, a numerical simulation and parametric study are conducted to assess the effectiveness of the control system for reducing the wind-induced vibration of the bridge towers during construction. The numerical simulation results show that the MSPMD is practical and effective for reducing the along-wind response of the single column tower, can be installed in a small area of the tower, and complies with the time-variant characteristics of the bridge during its entire construction stage.
基金supported by the National Natural Science Foundation of China under Grant No. 61303074 and No. 61309013the Henan Province Science and Technology Project Funds under Grant No. 12210231002
文摘Nowadays, security defence of network uses the game theory, which mostly applies complete information game model or even the static game model. To get closer to the actual network and defend actively, we propose a network attack-defence game model by using signalling game, which is modelled in the way of dynamic and incomplete information. We improve the traditional attack-defence strategies quantization method to meet the needs of the network signalling game model. Moreover, we give the calculation of the game equilibrium and analyse the optimal defence scheme. Finally, we analyse and verify effectiveness of the model and method through a simulation experiment.
基金Area Strategic Development Program in Structural Control and Intelligent Building from The Hong Kong Polytechnic UniversityNational Natural Science Foundation of China Under Grant No. 50408011
文摘The possibility of using a multi-stage pendulum mass damper (MSPMD) to control wind-induced vibration of a single column tower of a cable-stayed bridge during construction was studied theoretically in part I of this work. In this paper, the performance of the MSPMD for reducing bridge tower vibration is studied experimentally. A MSPMD model and a tower model of the bridge with geometry scaling of 1:100 were designed and manufactured. Calibration of the MSPMD model with different wire lengths is conducted to verify the analytical model of the damper. A series of tests for the uncontrolled freestanding tower, tower with cables, and tower with MSPMD model are then performed under harmonic and white noise excitations. The experimental results show that the responses of the tower model significantly decrease with the installation of the MSPMD model, which demonstrates the effectiveness of the M SPMD to mitigate the vibration of the bridge tower.