Owing to their global search capabilities and gradient-free operation,metaheuristic algorithms are widely applied to a wide range of optimization problems.However,their computational demands become prohibitive when ta...Owing to their global search capabilities and gradient-free operation,metaheuristic algorithms are widely applied to a wide range of optimization problems.However,their computational demands become prohibitive when tackling high-dimensional optimization challenges.To effectively address these challenges,this study introduces cooperative metaheuristics integrating dynamic dimension reduction(DR).Building upon particle swarm optimization(PSO)and differential evolution(DE),the proposed cooperative methods C-PSO and C-DE are developed.In the proposed methods,the modified principal components analysis(PCA)is utilized to reduce the dimension of design variables,thereby decreasing computational costs.The dynamic DR strategy implements periodic execution of modified PCA after a fixed number of iterations,resulting in the important dimensions being dynamically identified.Compared with the static one,the dynamic DR strategy can achieve precise identification of important dimensions,thereby enabling accelerated convergence toward optimal solutions.Furthermore,the influence of cumulative contribution rate thresholds on optimization problems with different dimensions is investigated.Metaheuristic algorithms(PSO,DE)and cooperative metaheuristics(C-PSO,C-DE)are examined by 15 benchmark functions and two engineering design problems(speed reducer and composite pressure vessel).Comparative results demonstrate that the cooperative methods achieve significantly superior performance compared to standard methods in both solution accuracy and computational efficiency.Compared to standard metaheuristic algorithms,cooperative metaheuristics achieve a reduction in computational cost of at least 40%.The cooperative metaheuristics can be effectively used to tackle both high-dimensional unconstrained and constrained optimization problems.展开更多
Different from the previous qualitative analysis of linear systems in time and frequency domains, the method for describing nonlinear systems quantitatively is proposed based on correlated dimensions. Nonlinear dynami...Different from the previous qualitative analysis of linear systems in time and frequency domains, the method for describing nonlinear systems quantitatively is proposed based on correlated dimensions. Nonlinear dynamics theory is used to analyze the pressure data of a contrarotating axial flow fan. The delay time is 18 and the embedded dimension varies from 1 to 25 through phase-space reconstruction. In addition, the correlated dimensions are calculated before and after stalling. The results show that the correlated dimensions drop from 1. 428 before stalling to 1. 198 after stalling, so they are sensitive to the stalling signal of the fan and can be used as a characteristic quantity for the judging of the fan stalling.展开更多
[Objective] The aim was to discuss the spatial pattern changes of land use in Tianjin new coastal area based on fractal dimensions.[Method] By dint of remote and geographic information system technology to obtain the ...[Objective] The aim was to discuss the spatial pattern changes of land use in Tianjin new coastal area based on fractal dimensions.[Method] By dint of remote and geographic information system technology to obtain the data of urban land use in new coastal area from 1993 to 2008,the boundary dimension,radius dimension and information dimension of each land use type were calculated based on fractal dimension.In addition,the revealed land use spatial dimension changes characteristics were analyzed.[Result] The spatial distribution of each land use type in new costal area had distinct fractal characteristics.And,the amount and changes of three types of dimension values effectively revealed the changes of complicatedness,centeredness and evenness of spatial pattern of land use in the study area.The boundary dimension of unused land and salty earth increased incessantly,which suggested its increasing complicatedness.The boundary of the port and wharf and shoal land was getting simpler.The radius dimension of the cultivated land was larger than 2,which suggested that its area spread from center to the surroundings;the one in salty land and waters distributed evenly within different radius space to the center of the city;the one in other land use types reduced gradually from center to the surroundings.The information dimension value in the woodland and orchard land,unused land and shoal land was small,and was in obvious concentrated distribution;the spatial distribution of cultivated and salty land concentrated in the outside area;the construction area in the port and wharf spread gradually on the basis of original state;the spatial distribution of waters and residents and mines were even.[Conclusion] Applying fractal dimensions to the study of spatial pattern changes of urban land use can make up for some disadvantages in classical urban spatial pattern quantitative research,which has favorable practical value.展开更多
The present status of self-elevating drilling units was analysed. Based on statistics of the main dimensions of self-elevating drilling units, a mathematical model was established using stepwise return procedures and ...The present status of self-elevating drilling units was analysed. Based on statistics of the main dimensions of self-elevating drilling units, a mathematical model was established using stepwise return procedures and a back-propagation neural network. mathematical model is applicable and reliable. The of the main dimensions of self-elevating drilling Analysis of examples of calculations showed that the model is useful for mastering the essential variations units and can be used for technical and economic analysis as well as in conceptual designs of drilling units.展开更多
随着电力系统的发展,现行的IEC标准IEC 60120《Dimensions of ball and socket couplings of string insulator units》(Third edition) 1984版已经无法涵盖和适应新的特高压大吨位绝缘子产品和技术的发展,包括对应于36和40两种新的联...随着电力系统的发展,现行的IEC标准IEC 60120《Dimensions of ball and socket couplings of string insulator units》(Third edition) 1984版已经无法涵盖和适应新的特高压大吨位绝缘子产品和技术的发展,包括对应于36和40两种新的联接标记的更高的强度等级的绝缘子。笔者介绍了IEC TC36/MT21工作组维护IEC 60120标准的主要内容:包括结合国际工程实践经验,将已经被广泛应用的36、40两个联接标记加入到本标准中;对Smin的表征意义进行重新理解和计算,并将其列入资料性附录供参考;解决了28B W型锁紧销是否在本次修订中纳入标准的问题;对socket章节的内容进行重新理解和研究,修正了原有的表述等。展开更多
Intercultural communication competence can help us adapt better to the host culture and deal with culture shock successfully. This paper mainly discusses the dimensions of intercultural communication competence.
The waterway in the middle and lower reaches of the Yangtze River has long been known as the Golden Waterway and has served as an important link in the construction of the Yangtze River Economic Belt.Therefore,expandi...The waterway in the middle and lower reaches of the Yangtze River has long been known as the Golden Waterway and has served as an important link in the construction of the Yangtze River Economic Belt.Therefore,expanding its dimensions is a significant goal,particularly given the long-range cumulative erosion occurring downstream of the Three Gorges Dam (TGD),which has been concentrated in the dry river channel.With the regulation of the volume from upstream reservoirs and the TGD,the minimum discharge and water level of the river downstream are increasing,and creating favorable conditions for the increase of the depth of the waterway.The discharge compensation effect during the dry season offsets the decline in the water level of the river channel caused by the down-cutting of part of the riverbed,but the minimum navigable water level of the segment near the dam still shows a declining trend.In recent years,several waterway remediation projects have been implemented in the downstream reaches of the TGD and although the waterway depth and width have been increased,the channel dimensions are still insufficient in the Yichang-Anqing reach (with a total length of 1026 km),as compared to the upstream reservoir area and the deep water channel in the downstream tidal reaches.A comprehensive analysis of the water depth and the number and length of shoals in the waterway indicates that its dimensions can be increased to 4.5 m ×200 m and 6.0 m×200 m in the Yichang-Wuhan and Wuhan-Anqing reaches,respectively.This is also feasible given the remediation technologies currently available,but remediation projects need to be coordinated with those for flood prevention and ecological protection.展开更多
Finite element method(FEM) simulations were employed to investigate the quenching residual stress distributions of 7085 aluminum alloy plates.The effect of dimensional variation on the quenching residual stress distri...Finite element method(FEM) simulations were employed to investigate the quenching residual stress distributions of 7085 aluminum alloy plates.The effect of dimensional variation on the quenching residual stress distributions was studied and discussed by using models with different dimensions(length,width,and thickness).The accuracy and efficiency of the models were verified by other numerical examples.The order of the dimension effects on the quenching residual stress distributions is:thickness> width=length.The maximum tensile stress and compressive stress increase from 33 to 190 and 39 to 270 MPa,respectively,as the thickness increases from 30 to 150 mm.The ultimate maximum tensile stress(about190 MPa) is equivalent to half of the quenching yield strength at 20℃,while the ultimate maximum compressive stress(about 300 MPa) is equivalent to 80 % of the quenching yield strength at 20℃.There are stress fluctuations at the edge of the large plate both in rolling and in transverse directions.The ratio of the fluctuation region along the rolling direction and transverse direction increases as the thickness increases,while it decreases as the length or width increases.The actual length of the fluctuation region is almost a constant value for the plates with a thickness of 115 mm(about 500 mm in length and 300 mm in width).展开更多
The linear relationship between fractal dimensions of a type of generalized Weierstrass functions and the order of their fractional calculus has been proved. The graphs and numerical results given here further indicat...The linear relationship between fractal dimensions of a type of generalized Weierstrass functions and the order of their fractional calculus has been proved. The graphs and numerical results given here further indicate the corresponding relationship.展开更多
Let R be a ring. We define a dimension, called P-cotorsion dimension, for modules and rings. The aim of this article is to investigate P-cotorsion dimensions of modules and rings and the relations between P-cotorsion ...Let R be a ring. We define a dimension, called P-cotorsion dimension, for modules and rings. The aim of this article is to investigate P-cotorsion dimensions of modules and rings and the relations between P-cotorsion dimension and other homological dimensions. This dimension has nice properties when the ring in consideration is generalized morphic.展开更多
Without much understanding of different cultures,it is common for people to hold stereotypes,which,negative or positive,hamper intercultural communication.Some North Americans are also stereotyped toward Chinese.Geert...Without much understanding of different cultures,it is common for people to hold stereotypes,which,negative or positive,hamper intercultural communication.Some North Americans are also stereotyped toward Chinese.Geert Hofstede’s cultural dimensions can be employed to discuss the cultural elements under the surface of their stereotypes.To be a successful communicator in diverse cultural background,understanding of the target culture and being tolerant of the diversity are significant.展开更多
In this paper, we consider the heat flow for the Hsystem with constant mean curvature in higher dimensions. We give sufficient conditions on the initial data such that the heat flow develops finite time singularity. W...In this paper, we consider the heat flow for the Hsystem with constant mean curvature in higher dimensions. We give sufficient conditions on the initial data such that the heat flow develops finite time singularity. We also provide a new set of initial data to guarantee the existence of global regular solution to the heat flow, that converges to zero in W 1,n with the decay rate t 2/（2-n） as time goes to infinity.展开更多
Fractional integral of continuous functions has been discussed in the present paper. If the order of Riemann-Liouville fractional integral is v, fractal dimension of Riemann-Liouville fractional integral of any contin...Fractional integral of continuous functions has been discussed in the present paper. If the order of Riemann-Liouville fractional integral is v, fractal dimension of Riemann-Liouville fractional integral of any continuous functions on a closed interval is no more than 2 - v.展开更多
Laser–plasma instability(LPI)is one of the main obstacles to achieving predictable and reproducible fusion at high gain through laser-driven inertial confinement fusion(ICF).In this paper,for the first time,we show a...Laser–plasma instability(LPI)is one of the main obstacles to achieving predictable and reproducible fusion at high gain through laser-driven inertial confinement fusion(ICF).In this paper,for the first time,we show analytically and confirm with three-dimensional particle-incell simulations that angular incoherence provides suppression of the instability growth rate that is additional to and much stronger than that provided by the well-known temporal and spatial incoherence usually used in ICF studies.For the model used in our calculations,the maximum field ratio between the stimulated Raman scattering and the driving pulses drops from 0.2 for a Laguerre–Gaussian pulse with a single nonzero topological charge to 0.05 for a super light spring with an angular momentum spread and random relative phases.In particular,angular incoherence does not introduce extra undesirable hot electrons.This provides a novel method for suppressing LPI by using light with an angular momentum spread and paves the way towards a low-LPI laser system for inertial fusion energy with a super light spring of incoherence in all dimensions of time,space,and angle,and may open the door to the use of longer-wavelength lasers for inertial fusion energy.展开更多
Let A be an Artin algebra.We investigate subalgebras of A with certain conditions and obtain some classes of algebras whose finitistic dimensions are finite.
1 Introduction In the present paper, we consider the Cauchy problem of the Klein-Gordon-Zakharov equations with different propagation speeds in three space dimensions:
Obtaining small carbides is crucial but difficult for high-speed steels.A new approach for refining carbide dimensions in M42 super hard high-speed steel by increasing cooling rate and spheroidizing treatment was prop...Obtaining small carbides is crucial but difficult for high-speed steels.A new approach for refining carbide dimensions in M42 super hard high-speed steel by increasing cooling rate and spheroidizing treatment was proposed.The morphologies and properties of eutectic carbides formed at different cooling rates were investigated by means of scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,electron back-scattered diffraction（EBSD）and differential scanning calorimeter（DSC）.The results show that eutectic carbides change from a lamellar shape into a curved-rod shape as cooling rate increases.Despite different morphologies,the two carbides are both of M2C type with a hexagonal close-packed structure and display a single crystal orientation in one eutectic colony.The morphology of M2C mainly depends on the growing process of eutectic carbides,which is strongly influenced by cooling rate.Compared with lamellar carbides,M2C carbides with curved-rod shapes are less stable,and decompose into M6 C and MC at lower temperatures.They are more inclined to spheroidize during heating,which ultimately and distinguishably refines the carbide dimensions.As small carbides are much easier to dissolve into matrices during austenization,the process described herein improves the supersaturation of alloying elements in martensite,which leads to an increment of hardness in M42 steel.展开更多
In basic homological algebra, the flat and injective dimensions of modules play an important and fundamental role. In this paper, the closely related IFP-flat and IFP-injective dimensions are introduced and studied. W...In basic homological algebra, the flat and injective dimensions of modules play an important and fundamental role. In this paper, the closely related IFP-flat and IFP-injective dimensions are introduced and studied. We show that IFP-fd（M） = IFP-id（M＋） and IFP-fd（M＋）=IFP-id（M） for any R-module M over any ring R. Let ：Z-In （resp., ＂Zgv,~） he the class of all left （resp., right） R-modules of IFP-injective （resp., IFP-flat） dimension at most n. We prove that every right R-module has an IFn- preenvelope, （IFn,IF⊥n） is a perfect cotorsion theory over any ring R, and for any ring R with IFP-id（RR） 〈 n, （IIn,II⊥n） is a perfect cotorsion theory. This generalizes and improves the earlier work （J. Algebra 242 （2001）, 447-459）. Finally, some applications are given.展开更多
Potassium ion batteries(PIBs)with the prominent advantages of sufficient reserves and economical cost are attractive candidates of new rechargeable batteries for large-grid electrochemical energy storage systems(EESs)...Potassium ion batteries(PIBs)with the prominent advantages of sufficient reserves and economical cost are attractive candidates of new rechargeable batteries for large-grid electrochemical energy storage systems(EESs).However,there are still some obstacles like large size of K+to commercial PIBs applications.Therefore,rational structural design based on appropriate materials is essential to obtain practical PIBs anode with K+accommodated and fast diffused.Nanostructural design has been considered as one of the effective strategies to solve these issues owing to unique physicochemical properties.Accordingly,quite a few recent anode materials with different dimensions in PIBs have been reported,mainly involving in carbon materials,metal-based chalcogenides(MCs),metal-based oxides(MOs),and alloying materials.Among these anodes,nanostructural carbon materials with shorter ionic transfer path are beneficial for decreasing the resistances of transportation.Besides,MCs,MOs,and alloying materials with nanostructures can effectively alleviate their stress changes.Herein,these materials are classified into 0D,1D,2D,and 3D.Particularly,the relationship between different dimensional structures and the corresponding electrochemical performances has been outlined.Meanwhile,some strategies are proposed to deal with the current disadvantages.Hope that the readers are enlightened from this review to carry out further experiments better.展开更多
基金funded by National Natural Science Foundation of China(Nos.12402142,11832013 and 11572134)Natural Science Foundation of Hubei Province(No.2024AFB235)+1 种基金Hubei Provincial Department of Education Science and Technology Research Project(No.Q20221714)the Opening Foundation of Hubei Key Laboratory of Digital Textile Equipment(Nos.DTL2023019 and DTL2022012).
文摘Owing to their global search capabilities and gradient-free operation,metaheuristic algorithms are widely applied to a wide range of optimization problems.However,their computational demands become prohibitive when tackling high-dimensional optimization challenges.To effectively address these challenges,this study introduces cooperative metaheuristics integrating dynamic dimension reduction(DR).Building upon particle swarm optimization(PSO)and differential evolution(DE),the proposed cooperative methods C-PSO and C-DE are developed.In the proposed methods,the modified principal components analysis(PCA)is utilized to reduce the dimension of design variables,thereby decreasing computational costs.The dynamic DR strategy implements periodic execution of modified PCA after a fixed number of iterations,resulting in the important dimensions being dynamically identified.Compared with the static one,the dynamic DR strategy can achieve precise identification of important dimensions,thereby enabling accelerated convergence toward optimal solutions.Furthermore,the influence of cumulative contribution rate thresholds on optimization problems with different dimensions is investigated.Metaheuristic algorithms(PSO,DE)and cooperative metaheuristics(C-PSO,C-DE)are examined by 15 benchmark functions and two engineering design problems(speed reducer and composite pressure vessel).Comparative results demonstrate that the cooperative methods achieve significantly superior performance compared to standard methods in both solution accuracy and computational efficiency.Compared to standard metaheuristic algorithms,cooperative metaheuristics achieve a reduction in computational cost of at least 40%.The cooperative metaheuristics can be effectively used to tackle both high-dimensional unconstrained and constrained optimization problems.
基金Supported by the Natural Science Foundation of Jiangsu Province(BK2005018)the Graduate Research and Innovation Plan of Jiangsu Province(CX07B-061Z)~~
文摘Different from the previous qualitative analysis of linear systems in time and frequency domains, the method for describing nonlinear systems quantitatively is proposed based on correlated dimensions. Nonlinear dynamics theory is used to analyze the pressure data of a contrarotating axial flow fan. The delay time is 18 and the embedded dimension varies from 1 to 25 through phase-space reconstruction. In addition, the correlated dimensions are calculated before and after stalling. The results show that the correlated dimensions drop from 1. 428 before stalling to 1. 198 after stalling, so they are sensitive to the stalling signal of the fan and can be used as a characteristic quantity for the judging of the fan stalling.
基金Supported by National Natural Science Fund Program(40705038)~~
文摘[Objective] The aim was to discuss the spatial pattern changes of land use in Tianjin new coastal area based on fractal dimensions.[Method] By dint of remote and geographic information system technology to obtain the data of urban land use in new coastal area from 1993 to 2008,the boundary dimension,radius dimension and information dimension of each land use type were calculated based on fractal dimension.In addition,the revealed land use spatial dimension changes characteristics were analyzed.[Result] The spatial distribution of each land use type in new costal area had distinct fractal characteristics.And,the amount and changes of three types of dimension values effectively revealed the changes of complicatedness,centeredness and evenness of spatial pattern of land use in the study area.The boundary dimension of unused land and salty earth increased incessantly,which suggested its increasing complicatedness.The boundary of the port and wharf and shoal land was getting simpler.The radius dimension of the cultivated land was larger than 2,which suggested that its area spread from center to the surroundings;the one in salty land and waters distributed evenly within different radius space to the center of the city;the one in other land use types reduced gradually from center to the surroundings.The information dimension value in the woodland and orchard land,unused land and shoal land was small,and was in obvious concentrated distribution;the spatial distribution of cultivated and salty land concentrated in the outside area;the construction area in the port and wharf spread gradually on the basis of original state;the spatial distribution of waters and residents and mines were even.[Conclusion] Applying fractal dimensions to the study of spatial pattern changes of urban land use can make up for some disadvantages in classical urban spatial pattern quantitative research,which has favorable practical value.
基金Supported by the National 863 Plan Foundation under Grant No.2003AA414060
文摘The present status of self-elevating drilling units was analysed. Based on statistics of the main dimensions of self-elevating drilling units, a mathematical model was established using stepwise return procedures and a back-propagation neural network. mathematical model is applicable and reliable. The of the main dimensions of self-elevating drilling Analysis of examples of calculations showed that the model is useful for mastering the essential variations units and can be used for technical and economic analysis as well as in conceptual designs of drilling units.
文摘Intercultural communication competence can help us adapt better to the host culture and deal with culture shock successfully. This paper mainly discusses the dimensions of intercultural communication competence.
基金supported by the National Key Research and Development Program of China(Grants No.2016YFC0402306 and 2016YFC0402106)the National Natural Science Foundation of China(Grant No.51809131)+1 种基金the Key Laboratory of Yellow River Sediment Research,Ministry of Water Resources of China(Grant No.2016002)the Fundamental Research Funds for Central Public Welfare Research Institutes(Grants No.TKS160103,TKS180201,and TKS180411)
文摘The waterway in the middle and lower reaches of the Yangtze River has long been known as the Golden Waterway and has served as an important link in the construction of the Yangtze River Economic Belt.Therefore,expanding its dimensions is a significant goal,particularly given the long-range cumulative erosion occurring downstream of the Three Gorges Dam (TGD),which has been concentrated in the dry river channel.With the regulation of the volume from upstream reservoirs and the TGD,the minimum discharge and water level of the river downstream are increasing,and creating favorable conditions for the increase of the depth of the waterway.The discharge compensation effect during the dry season offsets the decline in the water level of the river channel caused by the down-cutting of part of the riverbed,but the minimum navigable water level of the segment near the dam still shows a declining trend.In recent years,several waterway remediation projects have been implemented in the downstream reaches of the TGD and although the waterway depth and width have been increased,the channel dimensions are still insufficient in the Yichang-Anqing reach (with a total length of 1026 km),as compared to the upstream reservoir area and the deep water channel in the downstream tidal reaches.A comprehensive analysis of the water depth and the number and length of shoals in the waterway indicates that its dimensions can be increased to 4.5 m ×200 m and 6.0 m×200 m in the Yichang-Wuhan and Wuhan-Anqing reaches,respectively.This is also feasible given the remediation technologies currently available,but remediation projects need to be coordinated with those for flood prevention and ecological protection.
基金financially supported by the National Basic Research Program of China(No.2012CB619504)the National Natural Science Foundation of China(No.51274046)
文摘Finite element method(FEM) simulations were employed to investigate the quenching residual stress distributions of 7085 aluminum alloy plates.The effect of dimensional variation on the quenching residual stress distributions was studied and discussed by using models with different dimensions(length,width,and thickness).The accuracy and efficiency of the models were verified by other numerical examples.The order of the dimension effects on the quenching residual stress distributions is:thickness> width=length.The maximum tensile stress and compressive stress increase from 33 to 190 and 39 to 270 MPa,respectively,as the thickness increases from 30 to 150 mm.The ultimate maximum tensile stress(about190 MPa) is equivalent to half of the quenching yield strength at 20℃,while the ultimate maximum compressive stress(about 300 MPa) is equivalent to 80 % of the quenching yield strength at 20℃.There are stress fluctuations at the edge of the large plate both in rolling and in transverse directions.The ratio of the fluctuation region along the rolling direction and transverse direction increases as the thickness increases,while it decreases as the length or width increases.The actual length of the fluctuation region is almost a constant value for the plates with a thickness of 115 mm(about 500 mm in length and 300 mm in width).
文摘The linear relationship between fractal dimensions of a type of generalized Weierstrass functions and the order of their fractional calculus has been proved. The graphs and numerical results given here further indicate the corresponding relationship.
基金supported by Collegial Natural Science Research Program of Education Department of Jiangsu Province (07KJD110043)
文摘Let R be a ring. We define a dimension, called P-cotorsion dimension, for modules and rings. The aim of this article is to investigate P-cotorsion dimensions of modules and rings and the relations between P-cotorsion dimension and other homological dimensions. This dimension has nice properties when the ring in consideration is generalized morphic.
文摘Without much understanding of different cultures,it is common for people to hold stereotypes,which,negative or positive,hamper intercultural communication.Some North Americans are also stereotyped toward Chinese.Geert Hofstede’s cultural dimensions can be employed to discuss the cultural elements under the surface of their stereotypes.To be a successful communicator in diverse cultural background,understanding of the target culture and being tolerant of the diversity are significant.
文摘In this paper, we consider the heat flow for the Hsystem with constant mean curvature in higher dimensions. We give sufficient conditions on the initial data such that the heat flow develops finite time singularity. We also provide a new set of initial data to guarantee the existence of global regular solution to the heat flow, that converges to zero in W 1,n with the decay rate t 2/（2-n） as time goes to infinity.
文摘Fractional integral of continuous functions has been discussed in the present paper. If the order of Riemann-Liouville fractional integral is v, fractal dimension of Riemann-Liouville fractional integral of any continuous functions on a closed interval is no more than 2 - v.
基金This work was supported by the National Key R&D Program of China(Grant No.2018YFA0404803)the National Natural Science Foundation of China(Grant Nos.11922515,11935008,11335013,and 12035002).
文摘Laser–plasma instability(LPI)is one of the main obstacles to achieving predictable and reproducible fusion at high gain through laser-driven inertial confinement fusion(ICF).In this paper,for the first time,we show analytically and confirm with three-dimensional particle-incell simulations that angular incoherence provides suppression of the instability growth rate that is additional to and much stronger than that provided by the well-known temporal and spatial incoherence usually used in ICF studies.For the model used in our calculations,the maximum field ratio between the stimulated Raman scattering and the driving pulses drops from 0.2 for a Laguerre–Gaussian pulse with a single nonzero topological charge to 0.05 for a super light spring with an angular momentum spread and random relative phases.In particular,angular incoherence does not introduce extra undesirable hot electrons.This provides a novel method for suppressing LPI by using light with an angular momentum spread and paves the way towards a low-LPI laser system for inertial fusion energy with a super light spring of incoherence in all dimensions of time,space,and angle,and may open the door to the use of longer-wavelength lasers for inertial fusion energy.
基金Supported by the NSFC (10771112)NSF of Shandong Province (Y2008A05)
文摘Let A be an Artin algebra.We investigate subalgebras of A with certain conditions and obtain some classes of algebras whose finitistic dimensions are finite.
基金Foundation item: This work is supported by National Natural Science Foundation of P. R. China(No. 10271084).
文摘1 Introduction In the present paper, we consider the Cauchy problem of the Klein-Gordon-Zakharov equations with different propagation speeds in three space dimensions:
基金Item Sponsored by National Natural Science Foundation of China(51301038,51201031,51371050)Industry-Academia-Research Program of Jiangsu Province of China(BY2014127-03)+1 种基金Natural Science Foundation of Jiangsu Province of China(BK20141306)Jiangsu Province Key Laboratory of High-end Structural Materials of China(hsm1404)
文摘Obtaining small carbides is crucial but difficult for high-speed steels.A new approach for refining carbide dimensions in M42 super hard high-speed steel by increasing cooling rate and spheroidizing treatment was proposed.The morphologies and properties of eutectic carbides formed at different cooling rates were investigated by means of scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,electron back-scattered diffraction（EBSD）and differential scanning calorimeter（DSC）.The results show that eutectic carbides change from a lamellar shape into a curved-rod shape as cooling rate increases.Despite different morphologies,the two carbides are both of M2C type with a hexagonal close-packed structure and display a single crystal orientation in one eutectic colony.The morphology of M2C mainly depends on the growing process of eutectic carbides,which is strongly influenced by cooling rate.Compared with lamellar carbides,M2C carbides with curved-rod shapes are less stable,and decompose into M6 C and MC at lower temperatures.They are more inclined to spheroidize during heating,which ultimately and distinguishably refines the carbide dimensions.As small carbides are much easier to dissolve into matrices during austenization,the process described herein improves the supersaturation of alloying elements in martensite,which leads to an increment of hardness in M42 steel.
基金supported by National Natural Science Foundation of China(10961021,11001222)
文摘In basic homological algebra, the flat and injective dimensions of modules play an important and fundamental role. In this paper, the closely related IFP-flat and IFP-injective dimensions are introduced and studied. We show that IFP-fd（M） = IFP-id（M＋） and IFP-fd（M＋）=IFP-id（M） for any R-module M over any ring R. Let ：Z-In （resp., ＂Zgv,~） he the class of all left （resp., right） R-modules of IFP-injective （resp., IFP-flat） dimension at most n. We prove that every right R-module has an IFn- preenvelope, （IFn,IF⊥n） is a perfect cotorsion theory over any ring R, and for any ring R with IFP-id（RR） 〈 n, （IIn,II⊥n） is a perfect cotorsion theory. This generalizes and improves the earlier work （J. Algebra 242 （2001）, 447-459）. Finally, some applications are given.
基金the Start-up Funding of Jinan University(Grant No.88016105 and Grant No.55800001)the discipline construction outstanding young backbone project(Grant No.12819023)the Fundamental Research Funds for the Central Universities(Grant No.11620317).
文摘Potassium ion batteries(PIBs)with the prominent advantages of sufficient reserves and economical cost are attractive candidates of new rechargeable batteries for large-grid electrochemical energy storage systems(EESs).However,there are still some obstacles like large size of K+to commercial PIBs applications.Therefore,rational structural design based on appropriate materials is essential to obtain practical PIBs anode with K+accommodated and fast diffused.Nanostructural design has been considered as one of the effective strategies to solve these issues owing to unique physicochemical properties.Accordingly,quite a few recent anode materials with different dimensions in PIBs have been reported,mainly involving in carbon materials,metal-based chalcogenides(MCs),metal-based oxides(MOs),and alloying materials.Among these anodes,nanostructural carbon materials with shorter ionic transfer path are beneficial for decreasing the resistances of transportation.Besides,MCs,MOs,and alloying materials with nanostructures can effectively alleviate their stress changes.Herein,these materials are classified into 0D,1D,2D,and 3D.Particularly,the relationship between different dimensional structures and the corresponding electrochemical performances has been outlined.Meanwhile,some strategies are proposed to deal with the current disadvantages.Hope that the readers are enlightened from this review to carry out further experiments better.
