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
Switched systems play an imperative role in modeling many real industrial systems with abrupt changes.Due to possible exposure to unreliable and complex physical environments,switching dynamics may simultaneously face...Switched systems play an imperative role in modeling many real industrial systems with abrupt changes.Due to possible exposure to unreliable and complex physical environments,switching dynamics may simultaneously face multiple faults,including the unexpected controller disconnect,the temporary mismatch between subsystems and desired corresponding controllers,and the intermittent disordering of mode transitions.These commonly arising faults may result in severe and detrimental impacts on the reliability and convergence of the closed-loop solution,thereby bringing significant yet challenging issues to be tackled.This paper provides the first attempt to investigate the stabilization problem for a class of constrained switched linear systems with multiple faults under mode-dependent dwell time(MDT).From a set-theory perspective,we demonstrate a critical necessary and sufficient stability condition for switched systems without uncertainties.Moreover,the non-conservative stability criterion is further extended to the perturbed switched systems with rigorous proof.A switching communication network example verifies the validity of the theoretical result and demonstrates their advantages.展开更多
The exponential growth of food demand due to the increasing global population has the potential to seriously threaten the quality and quantity of food supplies due to climate change.This study explores the utilisation...The exponential growth of food demand due to the increasing global population has the potential to seriously threaten the quality and quantity of food supplies due to climate change.This study explores the utilisation of green urban spaces for achieving food self-sufficiency by investigating the extent to which sustainable urban farms could be used to reduce the consumption of imported produce in the UK.It also examines urban farming stakeholders'perspective on how food self-sufficiency can help realise the SDGs especially SDG 2(Zero hunger)and SDG 13(Climate action).The study adopts a mixed method approach through a survey with 115 respondents and semi-structured interviews conducted with 12 respondents from 4 different urban farming stakeholder groups.The findings of this study presented a strong correlation between stakeholders who had concerns about where their food came from and the carbon footprint of imported produce.The research shows that,urban farms will no doubt play a vital role in the future of food security in our cities/communities and that the SDGs could be realised through sustainable urban farms implemented within the relevant planning regulations/policies.展开更多
In this paper,a new subclass of close-to-convex harmonic functions defined by differential operators is introduced.Some properties for functions belonging to that,such as,representation theorem,sufficient conditions,i...In this paper,a new subclass of close-to-convex harmonic functions defined by differential operators is introduced.Some properties for functions belonging to that,such as,representation theorem,sufficient conditions,inclusion relations,coefficient inequalities,growth and convex combination problems are obtained.In addition,the radius of starlike,the radius of convexity and convolution properties of this class are obtained.展开更多
In this paper,we get a necessary and sufficient condition such that a class of differential inequalities hold.Using this necessary and sufficient condition,we prove that a class of first order nonhomogeneous ordinary ...In this paper,we get a necessary and sufficient condition such that a class of differential inequalities hold.Using this necessary and sufficient condition,we prove that a class of first order nonhomogeneous ordinary differential equations have the Hyers-Ulam stability.And then,we prove that some first order nonhomogeneous ordinary differential equations and some second order nonhomogeneous ordinary differential equations do not have the Hyers-Ulam instability under some suitable conditions.展开更多
In this paper, the solution of the matrix second semi-tensor product equation A∘lX∘lB=Cis studied. Firstly, the solvability of the matrix-vector second semi-tensor product equation is investigated. At the same time,...In this paper, the solution of the matrix second semi-tensor product equation A∘lX∘lB=Cis studied. Firstly, the solvability of the matrix-vector second semi-tensor product equation is investigated. At the same time, the compatibility conditions, the sufficient and necessary conditions and the specific solution methods for the matrix solution are given. Secondly, we further consider the solvability of the second semi-tensor product equation of the matrix. For each part, several examples are given to illustrate the validity of the results.展开更多
Hanson and Mond have grven sets of necessary and sufficient conditions for optimality in constrained optimization by introducing classes of generalized functions, called type Ⅰ functions. Recently, Bector definded un...Hanson and Mond have grven sets of necessary and sufficient conditions for optimality in constrained optimization by introducing classes of generalized functions, called type Ⅰ functions. Recently, Bector definded univex functions, a new class of functions that unifies several concepts of generalized convexity. In this paper, additional conditions are attached to the Kuhn Tucker conditions giving a set of conditions which are both necessary and sufficient for optimality in constrained optimization, under appropriate constraint qualifications.展开更多
Mathematical models for burden descending process have been applied to obtain whole burden structures in blast furnace,whereas the accuracy of those burden descent models has not been sufficiently investigated.Special...Mathematical models for burden descending process have been applied to obtain whole burden structures in blast furnace,whereas the accuracy of those burden descent models has not been sufficiently investigated.Special evaluation method based on timeline burden profiles was established to quantitatively evaluate the error between experimental and modeled burden structures.Four existing burden descent models were utilized to describe the burden structure of a 1/20 scaled warm blast furnace.Input modeling conditions including initial burden profile,descending volumes in each time interval,and normalized descending velocity distribution were determined via special image processing technology.Modeled burden structures were evaluated combined with the published experimental data.It is found that all the models caught the main profile of the burden structure.Furthermore,the improved nonuniform descent model（Model IV）shows the highest level of precision especially when burden descends with unstable velocity distribution tendency.Meanwhile,the traditional nonuniform descent model（Model III）may also be desirable to model the burden descending process when the burden descending velocity presents a linear tendency.Finally,the uniform descent model（Model I）might be the first option for roughly predicting burden structure.展开更多
The Belt and Road is a concept that goes beyond the century.Whither will it take China?What kind of international order will it create?Such issues are less than sufficiently discussed by the Chinese academic circle an...The Belt and Road is a concept that goes beyond the century.Whither will it take China?What kind of international order will it create?Such issues are less than sufficiently discussed by the Chinese academic circle and can be quite confusing to the international community.Particularly,well-established American think tanks like the Centre for Strategic and International展开更多
This paper discusses chiefly the compactness of solution set of following equationswhere △ is the Laplacian in Sobolev’s sense, a;（x）,i= 0,1,…n, n≥ 3, are real square matrices of dimen-sion N×V , bounded an...This paper discusses chiefly the compactness of solution set of following equationswhere △ is the Laplacian in Sobolev’s sense, a;（x）,i= 0,1,…n, n≥ 3, are real square matrices of dimen-sion N×V , bounded and measurable in a bounded multiply connected domain Ω, the boundary S is as-sumed to be sufficiently smooth, u（x） is unknown vector, z = （x<sub>1</sub>,x<sub>2</sub>,…,x<sub>n</sub>） Ω R<sup>z</sup>,m≥1,|S<sub>1</sub>|issuperficial measure of the unit sphere of R<sup>Z</sup>, |i|=i<sub>1</sub>+ i<sub>2</sub> +… + i., △<sup>m</sup>=△(△<sup>m-1</sup>). ,（Ω）, ,（Ω）, … denote the classes of vectors or matrices whose elements belong to L,（Ω）,W,（Ω）,…. A vector or a matrix is said to be continuous differentiable, bounded and measurable if so are its ele-展开更多
We consider the existence and asymptotic behavior of singularly perturbed boundary value problem;εX″= b（X,t）X′,t ∈（0, 1）（1）X（0） =α, X（1） =β, （2）where, ε】0, is a sufficiently small parameter, b（X,t...We consider the existence and asymptotic behavior of singularly perturbed boundary value problem;εX″= b（X,t）X′,t ∈（0, 1）（1）X（0） =α, X（1） =β, （2）where, ε】0, is a sufficiently small parameter, b（X,t） is continuous in R×[0,1 ],α,βare prescribedboundary condition, and there is a function X<sub>0</sub>（t） satisfying the implicit equation b[X<sub>0</sub>（t）,t] 0t∈[0,1 ].Boundary value problem in this case is rarely studied by other mathematician, the auther has ever dis-cussed the autonomous equation corresponding the boundary value problem （1）,（2）. Generally speaking,the solution of the corresponding problem has boundary layer at each end of the time interval [0 ,1] , itsinner solution is commposed by one or several constant function, these constant is the zero point of the au-展开更多
Recent experiments have observed magnetic reconnection in laser-produced high-energy-density(HED)plasma bubbles.We perform two-dimensional(2-D)particle-in-cell(PIC)simulations to investigate magnetic reconnection betw...Recent experiments have observed magnetic reconnection in laser-produced high-energy-density(HED)plasma bubbles.We perform two-dimensional(2-D)particle-in-cell(PIC)simulations to investigate magnetic reconnection between two approaching HED plasma bubbles.It is found that the expanding velocity of the bubbles has a great influence on the process of magnetic reconnection.When the expanding velocity is small,a single X line reconnection is formed.However,when the expanding velocity is sufficiently large,we can observe a plasmoid in the vicinity of the X line.At the same time,the structures of the electromagnetic field in HED plasma reconnection are similar to that in Harris current sheet reconnection.展开更多
A one-dimensional two-layer Frenkel–Kontorova model is studied.Firstly,a feedback tracking control law is given.Then,the boundedness result for the error states of single particles of the model is derived using the L...A one-dimensional two-layer Frenkel–Kontorova model is studied.Firstly,a feedback tracking control law is given.Then,the boundedness result for the error states of single particles of the model is derived using the Lyapunov Method.Especially,the motion of single particles can be approximated analytically for the case of sufficiently large targeted velocity.Simulations illustrate the accuracy of the derived results.展开更多
1.Introduction Formulating an optimal roadmap to realizing the goals of peak carbon dioxide emissions and carbon neutrality calls for a systemic analysis of mesoscale structures at multiple levels and of their governi...1.Introduction Formulating an optimal roadmap to realizing the goals of peak carbon dioxide emissions and carbon neutrality calls for a systemic analysis of mesoscale structures at multiple levels and of their governing multiobjective mechanisms within different sectors and fields.However,the analyses currently available are mostly based on traditional approaches,which have not considered different levels of complexity and heterogeneity sufficiently,or have not accounted for multiple objectives sufficiently reasonably.In this perspective article,we attempt to figure out a new framework for dealing with this challenging issue within a totally different paradigm for multiscale complex systems,in which such a global challenge and the paradigm shift in science need to be addressed jointly.展开更多
Back to the 1950s,Anderson revealed the absence of wave diffusion,i.e.,Anderson localization,in a sufficiently disordered media,marking the start of electron transport research in non-periodic lattices.[1]In a simplif...Back to the 1950s,Anderson revealed the absence of wave diffusion,i.e.,Anderson localization,in a sufficiently disordered media,marking the start of electron transport research in non-periodic lattices.[1]In a simplified theoretical model,one critical order parameter was proposed to determine the boundary of electron delocalization。展开更多
The formation of the Moon remains obscure after＊400 years since Galileo saw that the Moon was mountainous in 1609.The current hypothesis is that the Moon formed through a low-angle collision between the Earth and Mar...The formation of the Moon remains obscure after＊400 years since Galileo saw that the Moon was mountainous in 1609.The current hypothesis is that the Moon formed through a low-angle collision between the Earth and Mar-size impactor,which is known as the Giant Impact model（e.g.Benz et al.1989）.The giant impact should be sufficiently展开更多
专利名称:Collocation of radiation generator components for limited-space devices1(中文译名:有限空间装置用辐射发生器部件的配置1)专利申请号:US201514975640申请日:2015.12.18公开号:US10116232B2公开日:2018.10.30申请人:SCHLU...专利名称:Collocation of radiation generator components for limited-space devices1(中文译名:有限空间装置用辐射发生器部件的配置1)专利申请号:US201514975640申请日:2015.12.18公开号:US10116232B2公开日:2018.10.30申请人:SCHLUMBERGER TECHNOLOGY CORP;A compact radiation generator for use in a downhole well-logging tool is disclosed.The compact radiation generator comprises a housing with a cavity,a linear acceleration tube in the cavity that generates radiation when supplied with a sufficiently high voltage,and a first voltage multiplier ladder in the cavity configured to supply the sufficiently high voltage to the acceleration tube.The first voltage multiplier ladder is folded into two linear parts that are collocated to each other.展开更多
In order to study the mechanism of confined water inrush from coal seam floor,the main influences on permeability in the process of triaxial seepage experiments were analyzed with methods such as laboratory experiment...In order to study the mechanism of confined water inrush from coal seam floor,the main influences on permeability in the process of triaxial seepage experiments were analyzed with methods such as laboratory experiments,theoretical analysis and mechanical model calculation.The crack extension rule and the ultimate destruction form of the rock specimens were obtained.The mechanism of water inrush was explained reasonably from mechanical point of view.The practical criterion of water inrush was put forward.The results show that the rock permeability "mutation" phenomenon reflects the differences of stress state and cracks extension rate when the rock internal crack begins to extend in large-scale.The rock ultimate destruction form is related to the rock lithology and the angle between crack and principal stress.The necessary condition of floor water inrush is that the mining pressure leads to the extension and transfixion of the crack.The sufficient condition of floor water inrush is that the confined water’s expansionary stress in normal direction and shear stress in tangential direction must be larger than the internal stress in the crack.With the two conditions satisfied at the same time,the floor water inrush accident will occur.展开更多
The present study is aimed to investigate the ability of different intensity measures （IMs）, including response spectral acceleration at the fundamental period of the structure, Sa（T1）, as a common scalar IM and t...The present study is aimed to investigate the ability of different intensity measures （IMs）, including response spectral acceleration at the fundamental period of the structure, Sa（T1）, as a common scalar IM and twelve vector-valued IMs for seismic collapse assessment of structures. The vector-valued IMs consist of two components, with S（T1） as the first component and different parameters that are ratios of scalar IMs, as well as the spectral shape proxies εSa and N, as the second component. After investigating the properties of an optimal IM, a new vector-valued IM that includes the ratio of Sa（T1） to the displacement spectrum intensity （DSI） as the second component is proposed. The new IM is more efficient than other IMs for predicting the collapse capacity of structures. It is also sufficient with respect to magnitude, source-to-site distance, and scale factor for collapse capacity prediction of structures. To satisfy the predictability criterion, a ground motion prediction equation （GMPE） is determined for Sa（T1）/DSI by using the existing GMPEs. Furthermore, an empirical equation is proposed for obtaining the correlation between the components of the proposed IM. The results of this study show that using the new vector-valued IM leads to a more reliable seismic collapse assessment of structures.展开更多
This paper analyzes the performance of the orthogonal matching pursuit （OMP） algorithm in recovering sparse signals from noisy measurement. Considering the fact that some matrices satisfy some restricted isometry pr...This paper analyzes the performance of the orthogonal matching pursuit （OMP） algorithm in recovering sparse signals from noisy measurement. Considering the fact that some matrices satisfy some restricted isometry properties （RIPs） but not the coherence condition, a superior RIP-based condition is proposed, which means that if the measurement matrix satisfies δk＋1 〈 1/（2 ＋ √k） and the minimum component signal-to-noise ratio （MCSNR） is bounded, the OMP algorithm can exactly identify the support of the original sparse signal within k iterations. Finally, the theoretical results are verified by numerical simulations con- cerning different values of MCSNR and noise levels.展开更多
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.
基金supported in part by the Natural Sciences and Engineering Research Council of Canada(NSERC)supported by the National Natural Science Foundation of China under Grant 62303403Zhejiang Provincial Natural Science Foundation of China under Grants LR25F030004 and LQ24F030022。
文摘Switched systems play an imperative role in modeling many real industrial systems with abrupt changes.Due to possible exposure to unreliable and complex physical environments,switching dynamics may simultaneously face multiple faults,including the unexpected controller disconnect,the temporary mismatch between subsystems and desired corresponding controllers,and the intermittent disordering of mode transitions.These commonly arising faults may result in severe and detrimental impacts on the reliability and convergence of the closed-loop solution,thereby bringing significant yet challenging issues to be tackled.This paper provides the first attempt to investigate the stabilization problem for a class of constrained switched linear systems with multiple faults under mode-dependent dwell time(MDT).From a set-theory perspective,we demonstrate a critical necessary and sufficient stability condition for switched systems without uncertainties.Moreover,the non-conservative stability criterion is further extended to the perturbed switched systems with rigorous proof.A switching communication network example verifies the validity of the theoretical result and demonstrates their advantages.
文摘The exponential growth of food demand due to the increasing global population has the potential to seriously threaten the quality and quantity of food supplies due to climate change.This study explores the utilisation of green urban spaces for achieving food self-sufficiency by investigating the extent to which sustainable urban farms could be used to reduce the consumption of imported produce in the UK.It also examines urban farming stakeholders'perspective on how food self-sufficiency can help realise the SDGs especially SDG 2(Zero hunger)and SDG 13(Climate action).The study adopts a mixed method approach through a survey with 115 respondents and semi-structured interviews conducted with 12 respondents from 4 different urban farming stakeholder groups.The findings of this study presented a strong correlation between stakeholders who had concerns about where their food came from and the carbon footprint of imported produce.The research shows that,urban farms will no doubt play a vital role in the future of food security in our cities/communities and that the SDGs could be realised through sustainable urban farms implemented within the relevant planning regulations/policies.
基金Supported by the Natural Science Foundation of Inner Mongolia(Grant Nos.2024MS01014,2022MS01004)the Higher-School Science Foundation of Inner Mongolia(Grant No.NJZZ19209)。
文摘In this paper,a new subclass of close-to-convex harmonic functions defined by differential operators is introduced.Some properties for functions belonging to that,such as,representation theorem,sufficient conditions,inclusion relations,coefficient inequalities,growth and convex combination problems are obtained.In addition,the radius of starlike,the radius of convexity and convolution properties of this class are obtained.
基金Supported by Natural Science Research Projects of Liaoning Province Education Department(Grant No.LJ212410146024).
文摘In this paper,we get a necessary and sufficient condition such that a class of differential inequalities hold.Using this necessary and sufficient condition,we prove that a class of first order nonhomogeneous ordinary differential equations have the Hyers-Ulam stability.And then,we prove that some first order nonhomogeneous ordinary differential equations and some second order nonhomogeneous ordinary differential equations do not have the Hyers-Ulam instability under some suitable conditions.
文摘In this paper, the solution of the matrix second semi-tensor product equation A∘lX∘lB=Cis studied. Firstly, the solvability of the matrix-vector second semi-tensor product equation is investigated. At the same time, the compatibility conditions, the sufficient and necessary conditions and the specific solution methods for the matrix solution are given. Secondly, we further consider the solvability of the second semi-tensor product equation of the matrix. For each part, several examples are given to illustrate the validity of the results.
文摘Hanson and Mond have grven sets of necessary and sufficient conditions for optimality in constrained optimization by introducing classes of generalized functions, called type Ⅰ functions. Recently, Bector definded univex functions, a new class of functions that unifies several concepts of generalized convexity. In this paper, additional conditions are attached to the Kuhn Tucker conditions giving a set of conditions which are both necessary and sufficient for optimality in constrained optimization, under appropriate constraint qualifications.
基金Item Sponsored by National Natural Science Foundation of China(61290325)
文摘Mathematical models for burden descending process have been applied to obtain whole burden structures in blast furnace,whereas the accuracy of those burden descent models has not been sufficiently investigated.Special evaluation method based on timeline burden profiles was established to quantitatively evaluate the error between experimental and modeled burden structures.Four existing burden descent models were utilized to describe the burden structure of a 1/20 scaled warm blast furnace.Input modeling conditions including initial burden profile,descending volumes in each time interval,and normalized descending velocity distribution were determined via special image processing technology.Modeled burden structures were evaluated combined with the published experimental data.It is found that all the models caught the main profile of the burden structure.Furthermore,the improved nonuniform descent model（Model IV）shows the highest level of precision especially when burden descends with unstable velocity distribution tendency.Meanwhile,the traditional nonuniform descent model（Model III）may also be desirable to model the burden descending process when the burden descending velocity presents a linear tendency.Finally,the uniform descent model（Model I）might be the first option for roughly predicting burden structure.
文摘The Belt and Road is a concept that goes beyond the century.Whither will it take China?What kind of international order will it create?Such issues are less than sufficiently discussed by the Chinese academic circle and can be quite confusing to the international community.Particularly,well-established American think tanks like the Centre for Strategic and International
文摘This paper discusses chiefly the compactness of solution set of following equationswhere △ is the Laplacian in Sobolev’s sense, a;（x）,i= 0,1,…n, n≥ 3, are real square matrices of dimen-sion N×V , bounded and measurable in a bounded multiply connected domain Ω, the boundary S is as-sumed to be sufficiently smooth, u（x） is unknown vector, z = （x<sub>1</sub>,x<sub>2</sub>,…,x<sub>n</sub>） Ω R<sup>z</sup>,m≥1,|S<sub>1</sub>|issuperficial measure of the unit sphere of R<sup>Z</sup>, |i|=i<sub>1</sub>+ i<sub>2</sub> +… + i., △<sup>m</sup>=△(△<sup>m-1</sup>). ,（Ω）, ,（Ω）, … denote the classes of vectors or matrices whose elements belong to L,（Ω）,W,（Ω）,…. A vector or a matrix is said to be continuous differentiable, bounded and measurable if so are its ele-
文摘We consider the existence and asymptotic behavior of singularly perturbed boundary value problem;εX″= b（X,t）X′,t ∈（0, 1）（1）X（0） =α, X（1） =β, （2）where, ε】0, is a sufficiently small parameter, b（X,t） is continuous in R×[0,1 ],α,βare prescribedboundary condition, and there is a function X<sub>0</sub>（t） satisfying the implicit equation b[X<sub>0</sub>（t）,t] 0t∈[0,1 ].Boundary value problem in this case is rarely studied by other mathematician, the auther has ever dis-cussed the autonomous equation corresponding the boundary value problem （1）,（2）. Generally speaking,the solution of the corresponding problem has boundary layer at each end of the time interval [0 ,1] , itsinner solution is commposed by one or several constant function, these constant is the zero point of the au-
基金the National Natural Science Foundation of China under Grant Nos 11220101002,41174124,41274144 and 41121003the Key Research Program of Chinese Academy of Sciences(KZZD-EW-01)+1 种基金the National Basic Research Program of China(2012CB825602)the Ocean Public Welfare Scientific Research Project,State Oceanic Administration of China(No 201005017).
文摘Recent experiments have observed magnetic reconnection in laser-produced high-energy-density(HED)plasma bubbles.We perform two-dimensional(2-D)particle-in-cell(PIC)simulations to investigate magnetic reconnection between two approaching HED plasma bubbles.It is found that the expanding velocity of the bubbles has a great influence on the process of magnetic reconnection.When the expanding velocity is small,a single X line reconnection is formed.However,when the expanding velocity is sufficiently large,we can observe a plasmoid in the vicinity of the X line.At the same time,the structures of the electromagnetic field in HED plasma reconnection are similar to that in Harris current sheet reconnection.
基金by the U.S.National Science Foundation under Grant No CMMI 0825613.
文摘A one-dimensional two-layer Frenkel–Kontorova model is studied.Firstly,a feedback tracking control law is given.Then,the boundedness result for the error states of single particles of the model is derived using the Lyapunov Method.Especially,the motion of single particles can be approximated analytically for the case of sufficiently large targeted velocity.Simulations illustrate the accuracy of the derived results.
基金We appreciate the financial support from the Strategic Priority Research Program of Chinese Academy of Sciences(XDA21010102)the Science Challenge Project(TZ2018001)the International Partnership Program of Chinese Academy of Sciences(122111KYSB20170068).
文摘1.Introduction Formulating an optimal roadmap to realizing the goals of peak carbon dioxide emissions and carbon neutrality calls for a systemic analysis of mesoscale structures at multiple levels and of their governing multiobjective mechanisms within different sectors and fields.However,the analyses currently available are mostly based on traditional approaches,which have not considered different levels of complexity and heterogeneity sufficiently,or have not accounted for multiple objectives sufficiently reasonably.In this perspective article,we attempt to figure out a new framework for dealing with this challenging issue within a totally different paradigm for multiscale complex systems,in which such a global challenge and the paradigm shift in science need to be addressed jointly.
文摘Back to the 1950s,Anderson revealed the absence of wave diffusion,i.e.,Anderson localization,in a sufficiently disordered media,marking the start of electron transport research in non-periodic lattices.[1]In a simplified theoretical model,one critical order parameter was proposed to determine the boundary of electron delocalization。
文摘The formation of the Moon remains obscure after＊400 years since Galileo saw that the Moon was mountainous in 1609.The current hypothesis is that the Moon formed through a low-angle collision between the Earth and Mar-size impactor,which is known as the Giant Impact model（e.g.Benz et al.1989）.The giant impact should be sufficiently
文摘专利名称:Collocation of radiation generator components for limited-space devices1(中文译名:有限空间装置用辐射发生器部件的配置1)专利申请号:US201514975640申请日:2015.12.18公开号:US10116232B2公开日:2018.10.30申请人:SCHLUMBERGER TECHNOLOGY CORP;A compact radiation generator for use in a downhole well-logging tool is disclosed.The compact radiation generator comprises a housing with a cavity,a linear acceleration tube in the cavity that generates radiation when supplied with a sufficiently high voltage,and a first voltage multiplier ladder in the cavity configured to supply the sufficiently high voltage to the acceleration tube.The first voltage multiplier ladder is folded into two linear parts that are collocated to each other.
基金supported by the Youth Innovation Fund of China(KJ-2013-TDKC-15)the Fostering and Doctor Startup Initial Fund Program of Xi’an University of Science and Technology(201350,2014QDJ033).
文摘In order to study the mechanism of confined water inrush from coal seam floor,the main influences on permeability in the process of triaxial seepage experiments were analyzed with methods such as laboratory experiments,theoretical analysis and mechanical model calculation.The crack extension rule and the ultimate destruction form of the rock specimens were obtained.The mechanism of water inrush was explained reasonably from mechanical point of view.The practical criterion of water inrush was put forward.The results show that the rock permeability "mutation" phenomenon reflects the differences of stress state and cracks extension rate when the rock internal crack begins to extend in large-scale.The rock ultimate destruction form is related to the rock lithology and the angle between crack and principal stress.The necessary condition of floor water inrush is that the mining pressure leads to the extension and transfixion of the crack.The sufficient condition of floor water inrush is that the confined water’s expansionary stress in normal direction and shear stress in tangential direction must be larger than the internal stress in the crack.With the two conditions satisfied at the same time,the floor water inrush accident will occur.
文摘The present study is aimed to investigate the ability of different intensity measures （IMs）, including response spectral acceleration at the fundamental period of the structure, Sa（T1）, as a common scalar IM and twelve vector-valued IMs for seismic collapse assessment of structures. The vector-valued IMs consist of two components, with S（T1） as the first component and different parameters that are ratios of scalar IMs, as well as the spectral shape proxies εSa and N, as the second component. After investigating the properties of an optimal IM, a new vector-valued IM that includes the ratio of Sa（T1） to the displacement spectrum intensity （DSI） as the second component is proposed. The new IM is more efficient than other IMs for predicting the collapse capacity of structures. It is also sufficient with respect to magnitude, source-to-site distance, and scale factor for collapse capacity prediction of structures. To satisfy the predictability criterion, a ground motion prediction equation （GMPE） is determined for Sa（T1）/DSI by using the existing GMPEs. Furthermore, an empirical equation is proposed for obtaining the correlation between the components of the proposed IM. The results of this study show that using the new vector-valued IM leads to a more reliable seismic collapse assessment of structures.
基金supported by the National Natural Science Foundation of China(6117401661171197)
文摘This paper analyzes the performance of the orthogonal matching pursuit （OMP） algorithm in recovering sparse signals from noisy measurement. Considering the fact that some matrices satisfy some restricted isometry properties （RIPs） but not the coherence condition, a superior RIP-based condition is proposed, which means that if the measurement matrix satisfies δk＋1 〈 1/（2 ＋ √k） and the minimum component signal-to-noise ratio （MCSNR） is bounded, the OMP algorithm can exactly identify the support of the original sparse signal within k iterations. Finally, the theoretical results are verified by numerical simulations con- cerning different values of MCSNR and noise levels.
