Dear Editor,In this letter,a constrained networked predictive control strategy is proposed for the optimal control problem of complex nonlinear highorder fully actuated(HOFA)systems with noises.The method can effectiv...Dear Editor,In this letter,a constrained networked predictive control strategy is proposed for the optimal control problem of complex nonlinear highorder fully actuated(HOFA)systems with noises.The method can effectively deal with nonlinearities,constraints,and noises in the system,optimize the performance metric,and present an upper bound on the stable output of the system.展开更多
In this paper,we use the solution of the even functional Minkowski problem to show that there is a minimizing affine Minkowski total variation of the function of bounded variation.Moreover,for the Minkowski total vari...In this paper,we use the solution of the even functional Minkowski problem to show that there is a minimizing affine Minkowski total variation of the function of bounded variation.Moreover,for the Minkowski total variation,we use the method of convexation to establish the same conclusion as the convex body space.展开更多
Compared to traditional single-frequency bound states in the continuum(BIC),dual-band BIC of-fers higher degrees of freedom and functionality.Moveover,implementing independent control of dual-band BICs can further enh...Compared to traditional single-frequency bound states in the continuum(BIC),dual-band BIC of-fers higher degrees of freedom and functionality.Moveover,implementing independent control of dual-band BICs can further enhance their advantages and maximize their performance.This study presents a design for a dielectric metasurface that achieves dual-band BICs in the terahertz(THz)range.By adjusting two asym-metry parameters of the structure,independent control of the two symmetry-protected BICs is achieved.Fur-thermore,by varying the shape of the silicon holes,the design's robustness to geometric variations is demon-strated.Finally,the test results show that the figures of merit(FOMs)for both BICs reach 109.This work provides a new approach for realizing and tuning dual-frequency BICs,offering expanded possibilities for applications in multimode lasers,nonlinear optics,multi-channel filtering,and optical sensing.展开更多
A nowhere-zero k-flow on a graph G=(V(G),E(G))is a pair(D,f),where D is an orientation on E(G)and f:E(G)→{±1,±2,,±(k-1)}is a function such that the total outflow equals to the total inflow at each vert...A nowhere-zero k-flow on a graph G=(V(G),E(G))is a pair(D,f),where D is an orientation on E(G)and f:E(G)→{±1,±2,,±(k-1)}is a function such that the total outflow equals to the total inflow at each vertex.This concept was introduced by Tutte as an extension of face colorings,and Tutte in 1954 conjectured that every bridgeless graph admits a nowhere-zero 5-flow,known as the 5-Flow Conjecture.This conjecture is verified for some graph classes and remains unresolved as of today.In this paper,we show that every bridgeless graph of Euler genus at most 20 admits a nowhere-zero 5-flow,which improves several known results.展开更多
This letter presents a method for probing the attosecond time delay between two radiatively resonant transitions from Fano structures,which arise from interference between the extreme ultraviolet free induction decay(...This letter presents a method for probing the attosecond time delay between two radiatively resonant transitions from Fano structures,which arise from interference between the extreme ultraviolet free induction decay(XFID)emission and high-order harmonics.The ellipticity dependence of the Ne^(+)XFID yield confirms that the ionic excited-state populations originate from inelastic recollision between tunneling electrons and parent ions.Subsequent extraction of relative phases from Fano structures enables the determination of the time delay(~22 as)between the two decay pathways.This work provides an experimental approach to probe the attosecond time delay between different XFID channels and contributes to a deeper understanding of the tunneling-plusrescattering model in strong laser fields.展开更多
We present a study of the ion stopping power due to free and bound electrons in a warm dense plasma.Our main goal is to propose a method of stopping-power calculation expected to be valid for any ionization degree.The...We present a study of the ion stopping power due to free and bound electrons in a warm dense plasma.Our main goal is to propose a method of stopping-power calculation expected to be valid for any ionization degree.The free-electron contribution is described by the Maynard–Deutsch–Zimmerman formula,and the bound-electron contribution relies on the Bethe formula with corrections,in particular taking into account density and shell effects.The results of the bound-state computation using three different parametric potentials are investigated within the Garbet formalism for the mean excitation energy.The first parametric potential is due to Green,Sellin,and Zachor,the second one was proposed by Yunta,and the third one was introduced by Klapisch in the framework of atomic-structure computations.The results are compared with those of self-consistent average-atom calculations.This approach correctly bridges the limits of neutral and fully ionized matter.展开更多
The X(3872)is theoretically predicted to have a spin-0 partner state denoted as X_(0).Assuming the X_(0)as a molecular bound state,we calculate the decay widths of X_(0)→VV and X_(0)→PP(V and P stand for light vecto...The X(3872)is theoretically predicted to have a spin-0 partner state denoted as X_(0).Assuming the X_(0)as a molecular bound state,we calculate the decay widths of X_(0)→VV and X_(0)→PP(V and P stand for light vector and pseudoscalar mesons,respectively)via intermediate charmed meson loops.Three different configurations of the X_(0),i.e.,pure neutral components(θ=0),isospin singlet(θ=π/4),and pure charged components(θ=π/2),are investigated.Within a commonly accepted range of the model parameterα,the predicted decay widths of X_(0)→VV are on the order of a few hundred keV,while the decay widths of X_(0)→PP can reach several MeV.The X_(0)→ρρandππhave larger decay rates.The relative width ratios between the channels are nearly model-independent.Moreover,among those channels only with isovector or isoscalar mesons,the relevant ratios are also independent of the phase angle.The predicted ratios are helpful for searching the X_(0)in the future experiments at BESIII and Belle II.展开更多
We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-ly...We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-lying excited states to the 1s-muon state can lead to the production of electron-positron pairs.We show that the Breit interaction determines the transition probabilities for states with nonzero orbital momentum.We show that the pair production arises mainly from the decay of the 2p states.Thus,the Breit interaction governs electron-positron pair production in bound-bound muon transitions.This process offers a unique opportunity to explore quantum electrodynamics in strong fields,as well as a class of nonradiative transitions involving electron-positron pair production.展开更多
We propose a novel approach to generate and manipulate topological Floquet bound states in the continuum(BICs)via a class of systems constructed by coupling two identical periodically driven one-dimensional Su-Schrief...We propose a novel approach to generate and manipulate topological Floquet bound states in the continuum(BICs)via a class of systems constructed by coupling two identical periodically driven one-dimensional Su-Schrieffer-Heeger chains.The formation of topological Floquet BICs can be adjusted only by tuning the driving amplitude or frequency,regardless of whether the static system has BICs or not.The interchain bias can only change the localization property of topological Floquet BICs,and a bigger bias can lead to transforming topological Floquet BICs into bound states out of the continuum(BOCs).But it does not change the topological properties of these topological Floquet states.Based on the repulsion effect of edge states,we propose to detect occurrence of topological Floquet BICs and transition point between topological Floquet BICs and BOCs using quantum walk.Our work provided a convenient and realistic approach for the experimental realization and manipulation of BICs in a single-particle quantum system.展开更多
The capacity to predict X-ray transition and K-edge energies in dense finite-temperatur plasmas with high precision is of primary importance for atomic physics of matter under extreme conditions.The dual characteristi...The capacity to predict X-ray transition and K-edge energies in dense finite-temperatur plasmas with high precision is of primary importance for atomic physics of matter under extreme conditions.The dual characteristics of bound and continuum states in dense matter are modeled by a valence-band-like structure in a generalized ion-sphere approach with states that are either bound,free,or mixed.The self-consistent combination of this model with the Dirac wave equations of multielectron bound states allows one to fully respect the Pauli principle and to take into account the exact nonlocal exchange terms.The generalized method allows very high precision without implication of calibration shifts and scaling parameters and therefore has predictive power.This leads to new insights in the analysis of various data.The simple ionization model representing the K-edge is generalized to excitation–ionization phenomena resulting in an advanced interpretation of ionization depression data in near-solid-density plasmas.The model predicts scaling relations along the isoelectronic sequences and the existence of bound M-states that are in excellent agreement with experimental data,whereas other methods have failed.The application to unexplained data from compound materials also gives good agreement without the need to invoke any additional assumptions in the generalized model,whereas other methods have lacked consistency.展开更多
This study mainly focuses on the triangle bounded L⁃algebras and triangle ideals.Firstly,the definition of triangle bounded L⁃algebras is presented,and several examples with different conditions are outlined along wit...This study mainly focuses on the triangle bounded L⁃algebras and triangle ideals.Firstly,the definition of triangle bounded L⁃algebras is presented,and several examples with different conditions are outlined along with an exploration of their properties.Moreover,we investigate the structure of triangle bounded L⁃algebra with a special condition.Secondly,we define the concept of triangle ideals of triangle bounded L⁃algebra and explore the connection between the triangle ideals of triangle bounded L⁃algebra L and the ideals of bounded L⁃algebra E(L).In addition,we classified and studied various classes of triangle ideals,including Stonean triangle ideals,extended Stonean triangle ideals,and lattice ideals,and by introducing the notion of Stonean triangle bounded L algebras,we examine the relationship between Stonean triangle bounded L⁃algebras and Stonean triangle ideals.Finally,we investigate the interrelationships among these various types of triangle ideals.展开更多
For the process of multi-robot collaboration to lift the same lifted object by flexible cables,the existing collision detection algorithm of cables between the environmental obstacles has the problem of misjudgment an...For the process of multi-robot collaboration to lift the same lifted object by flexible cables,the existing collision detection algorithm of cables between the environmental obstacles has the problem of misjudgment and omission.In this work,the collision detection of cable vector was studied,and the purpose of collision detection was realized by algorithm.Considering the characteristics of cables themselves,based on oriented bounding box theory,the cable optimization model and environmental obstacle model were established,and a new basic geometric collision detection model was proposed.Then a fast cable vector collision detection algorithm and an optimization principle were proposed.Finally,the rationality of the cable collision detection model and the effectiveness of the proposed algorithm were verified by simulation.Simulation results show that the proposed method can meet the requirements of the fast detection and the accuracy in complex virtual environment.The results lay a foundation for obstacle avoidance motion planning of system.展开更多
Response analysis of structures involving non-probabilistic uncertain parameters can be closely related to optimization.This paper provides a review on optimization-based methods for uncertainty analysis,with focusing...Response analysis of structures involving non-probabilistic uncertain parameters can be closely related to optimization.This paper provides a review on optimization-based methods for uncertainty analysis,with focusing attention on specific properties of adopted numerical optimization approaches.We collect and discuss the methods based on nonlinear programming,semidefinite programming,mixed-integer programming,mathematical programming with complementarity constraints,difference-of-convex programming,optimization methods using surrogate models and machine learning techniques,and metaheuristics.As a closely related topic,we also overview the methods for assessing structural robustness using non-probabilistic uncertainty modeling.We conclude the paper by drawing several remarks through this review.展开更多
The flocculation behavior of carbon black (CB)-filled isoprene rubber (IR) nanocomposites was systematically investigated under both dynamic and static conditions to unravel the distinct mechanisms governing filler ne...The flocculation behavior of carbon black (CB)-filled isoprene rubber (IR) nanocomposites was systematically investigated under both dynamic and static conditions to unravel the distinct mechanisms governing filler network evolution.Under dynamic conditions,small oscillatory shear strains (0.1%) significantly enhanced filler particle motion,leading to pronounced agglomeration and a flocculation degree of about 4.3MPa at 145℃.In contrast,static flocculation exhibited a fundamentally different mechanism dominated by polymer chain dynamics,which is driven mainly by thermal activation.Radial distribution function (RDF) analysis of transmission electron microscopy (TEM) images revealed a slight decrease (2 nm) in the interparticle distance peak after static annealing at 100℃ for 7 h,indicating localized motion of CB particles.However,the overall filler network remained stable,with no significant agglomeration observed.The increase in bound rubber content from about 23% to 28% with rising temperature further confirmed the dominant role of polymer chain adsorption and interfacial reinforcement in static flocculation.These findings highlight the critical influence of external strain on filler network formation and provide new insights into the polymer-dominated mechanism of static flocculation.The results offer practical guidance for optimizing the storage and processing of rubber nanocomposites,particularly in applications where static flocculation during prolonged storage is a concern.展开更多
Currently,Robinia pseudoacacia L.is distributed extensively across the Chinese Loess Plateau.Root exudates released by Robinia pseudoacacia L.are one of the mechanisms through which Robinia pseudoacacia L.affects soil...Currently,Robinia pseudoacacia L.is distributed extensively across the Chinese Loess Plateau.Root exudates released by Robinia pseudoacacia L.are one of the mechanisms through which Robinia pseudoacacia L.affects soil properties.However,how root exudates influencethe hydraulic properties of soil remains unclear,especially for fine-grained soils.This knowledge gap impedes a comprehensive understanding of the function of vegetation in wastewater treatment,ecological restoration,and seepage analysis.To investigate the effect and underlying mechanisms of the root exudates of Robinia pseudoacacia L.on the saturated hydraulic conductivity of loess(a fine-grainedsoil),the saturated hydraulic conductivity,bound water content,grain size distribution,and microstructure characteristics of loess treated with root exudates at varying concentrations were determined in this study through a series of tests.The results show that the mean saturated hydraulic conductivities of the loess specimens with root exudates are all lower than those without root exudates.This phenomenon can be attributed primarily to the capacity of root exudates to directly and indirectly increase the bound water content,leading to a decrease in the effective seepage channels of the loess.For loess with/without root exudates,the variation of saturated hydraulic conductivity over time can be divided into three stages:an initial constant stage,a rapid reduction stage,and a re-stabilization stage.This is primarily attributed to the migration of particles within a specifiedsize range(7-30μm)and pore-clogging in the specimens during the seepage process.A schematic diagram is proposed for the structural evolution of fine-grained soil with or without root exudates during long-term seepage.展开更多
Elucidation of the interactions of crop plants with clay minerals is essential for understanding the roles of clay minerals in terrestrial ecosystems.The prevailing hypothesis suggests that the physiological barriers ...Elucidation of the interactions of crop plants with clay minerals is essential for understanding the roles of clay minerals in terrestrial ecosystems.The prevailing hypothesis suggests that the physiological barriers of plant roots prevent the direct uptake of these large-size particles.However,whether crops can directly take up clay mineral particles remains unknown.Montmorillonite is a ubiquitous and important clay mineral in soil.This study used covalent fluorescence labeling and microscopic techniques to investigate the uptake and transport of montmorillonite particles by wheat(Triticum aestivum L.)in hydroponic solution,quartz sand matrix,and sandy loam soil.Additionally,the surface attachments of montmorillonite particles in xylem sap were analyzed at the nanoscale level with transmission electron microscopy and atomic force microscopy combined with infrared spectroscopy.Our results confirmed that micrometer-sized montmorillonite particles could enter the root steles of wheat seedlings from the sites of new lateral root emergence and were subsequently transported upward to the shoots and leaves through the vasculature via the transpiration stream.In this process,the surfaces of the montmorillonites adsorbed inorganic mineral nutrients and were covered by a layer of biomolecular coronas.This study reveals the potential for crop plant uptake of micrometer-sized montmorillonite particles and complements existing theories regarding the interactions of clay minerals with crop plants.Furthermore,the findings may lay a foundation for future studies on clay mineral interactions with crop plants in terrestrial ecosystems.展开更多
Codebooks are widely applied in code division multiple access communication systems.Based on the subspaces of singular linear spaces over the finite fields,two classes of new codebooks are constructed.Firstly,a kind o...Codebooks are widely applied in code division multiple access communication systems.Based on the subspaces of singular linear spaces over the finite fields,two classes of new codebooks are constructed.Firstly,a kind of binary codebooks are constructed by using the subspace of the singular linear space over the finite fields.According to the anzahl theorem,the parameters and the maximum correlation amplitude I_(max)(C)of the codebooks are calculated,and then given the conditions that the I_(max)(C)asymptotically reaches the Welch bound.On this basis,by mixing with Hadamard matrices,the number of columns are increased and obtain another class of new code,which further relaxes the conditions that the I_(max)(C)asymptotically reaches the Welch bound.展开更多
The tiered geosynthetic-reinforced soil (GRS) walls have been increasingly applied in the high and steep retaining soil structures. However, very little is known about the design method for the tiered GRS wall in prac...The tiered geosynthetic-reinforced soil (GRS) walls have been increasingly applied in the high and steep retaining soil structures. However, very little is known about the design method for the tiered GRS wall in practice. This study is aimed at proposing an upper-bound stability analysis method of a tiered GRS wall. The proposed method was firstly validated by the existing results from the centrifuge test and the numerical method, and then a parametric study was performed to investigate the effects of the cohesionless backfill friction angle φ1 and the wall geometric parameters including the offset distance, the total wall height, the batter angle δ, the number of tiers n, and wall height ratio of adjacent tiers on the dimensionless equivalent earth pressure coefficient KT. The analysis results demonstrated that as the φ1 increases, the shear strength of backfill is enhanced and thus the KT or the total reinforcement tensile force decreases, and the KT decreases with the increase of the offset distance at the initial stage and then becomes stable when it reaches a certain critical value. For a fixed offset distance, the KT or the total reinforcement tensile force decreases with the increase of the δ. For the two-tiered GRS walls having the offset distance less than the critical value, the wall with the smaller wall height ratio has a larger KT. Further, the variation of the location of the critical failure surfaces of tiered GRS walls was presented in this study with the variation of the φ1 and the wall geometry.展开更多
In this paper,we study the eigenvalue problem of the Markov diffusion operator L^(2),and give generalized inequalities for eigenvalues of the operator L^(2)on a Markov diffusion triple.By applying these inequalities,w...In this paper,we study the eigenvalue problem of the Markov diffusion operator L^(2),and give generalized inequalities for eigenvalues of the operator L^(2)on a Markov diffusion triple.By applying these inequalities,we then get some new universal bounds for eigenvalues of a special Markov diffusion operator L^(2)on bounded domains in an Euclidean space.Moreover,our results can reveal the relationship between the(k+1)-th eigenvalue and the first k eigenvalues in a relatively straightforward manner.展开更多
It is known that monotone recurrence relations can induce a class of twist homeomorphisms on the high-dimensional cylinder,which is an extension of the class of monotone twist maps on the annulus or two-dimensional cy...It is known that monotone recurrence relations can induce a class of twist homeomorphisms on the high-dimensional cylinder,which is an extension of the class of monotone twist maps on the annulus or two-dimensional cylinder.By constructing a bounded solution of the monotone recurrence relation,the main conclusion in this paper is acquired:The induced homeomorphism has Birkhoff orbits provided there is a compact forward-invariant set.Therefore,it generalizes Angenent's results in low-dimensional cases.展开更多
基金supported in part by the National Natural Science Foundation of China(62173255,62188101)Shenzhen Key Laboratory of Control Theory and Intelligent Systems(ZDSYS20220330161800001)
文摘Dear Editor,In this letter,a constrained networked predictive control strategy is proposed for the optimal control problem of complex nonlinear highorder fully actuated(HOFA)systems with noises.The method can effectively deal with nonlinearities,constraints,and noises in the system,optimize the performance metric,and present an upper bound on the stable output of the system.
基金Supported in part by NSFC(No.11971005)the Fundamental Research Funds for the Central Universities(Nos.GK202101008,GK202102012)。
文摘In this paper,we use the solution of the even functional Minkowski problem to show that there is a minimizing affine Minkowski total variation of the function of bounded variation.Moreover,for the Minkowski total variation,we use the method of convexation to establish the same conclusion as the convex body space.
文摘Compared to traditional single-frequency bound states in the continuum(BIC),dual-band BIC of-fers higher degrees of freedom and functionality.Moveover,implementing independent control of dual-band BICs can further enhance their advantages and maximize their performance.This study presents a design for a dielectric metasurface that achieves dual-band BICs in the terahertz(THz)range.By adjusting two asym-metry parameters of the structure,independent control of the two symmetry-protected BICs is achieved.Fur-thermore,by varying the shape of the silicon holes,the design's robustness to geometric variations is demon-strated.Finally,the test results show that the figures of merit(FOMs)for both BICs reach 109.This work provides a new approach for realizing and tuning dual-frequency BICs,offering expanded possibilities for applications in multimode lasers,nonlinear optics,multi-channel filtering,and optical sensing.
文摘A nowhere-zero k-flow on a graph G=(V(G),E(G))is a pair(D,f),where D is an orientation on E(G)and f:E(G)→{±1,±2,,±(k-1)}is a function such that the total outflow equals to the total inflow at each vertex.This concept was introduced by Tutte as an extension of face colorings,and Tutte in 1954 conjectured that every bridgeless graph admits a nowhere-zero 5-flow,known as the 5-Flow Conjecture.This conjecture is verified for some graph classes and remains unresolved as of today.In this paper,we show that every bridgeless graph of Euler genus at most 20 admits a nowhere-zero 5-flow,which improves several known results.
基金supported by the National Natural Science Foundation of China(Grant Nos.12234020,12474281,12450403,and 12274461)the Science and Technology Innovation Program of Hunan Province(Grant No.2022RC1193).
文摘This letter presents a method for probing the attosecond time delay between two radiatively resonant transitions from Fano structures,which arise from interference between the extreme ultraviolet free induction decay(XFID)emission and high-order harmonics.The ellipticity dependence of the Ne^(+)XFID yield confirms that the ionic excited-state populations originate from inelastic recollision between tunneling electrons and parent ions.Subsequent extraction of relative phases from Fano structures enables the determination of the time delay(~22 as)between the two decay pathways.This work provides an experimental approach to probe the attosecond time delay between different XFID channels and contributes to a deeper understanding of the tunneling-plusrescattering model in strong laser fields.
文摘We present a study of the ion stopping power due to free and bound electrons in a warm dense plasma.Our main goal is to propose a method of stopping-power calculation expected to be valid for any ionization degree.The free-electron contribution is described by the Maynard–Deutsch–Zimmerman formula,and the bound-electron contribution relies on the Bethe formula with corrections,in particular taking into account density and shell effects.The results of the bound-state computation using three different parametric potentials are investigated within the Garbet formalism for the mean excitation energy.The first parametric potential is due to Green,Sellin,and Zachor,the second one was proposed by Yunta,and the third one was introduced by Klapisch in the framework of atomic-structure computations.The results are compared with those of self-consistent average-atom calculations.This approach correctly bridges the limits of neutral and fully ionized matter.
基金supported by the National Natural Science Foundation of China(Grant Nos.12475081 and 12105153)the Natural Science Foundation of Shandong Province(Grant Nos.ZR2021MA082 and ZR2022ZD26)Taishan Scholar Project of Shandong Province(Grant No.tsqn202103062).
文摘The X(3872)is theoretically predicted to have a spin-0 partner state denoted as X_(0).Assuming the X_(0)as a molecular bound state,we calculate the decay widths of X_(0)→VV and X_(0)→PP(V and P stand for light vector and pseudoscalar mesons,respectively)via intermediate charmed meson loops.Three different configurations of the X_(0),i.e.,pure neutral components(θ=0),isospin singlet(θ=π/4),and pure charged components(θ=π/2),are investigated.Within a commonly accepted range of the model parameterα,the predicted decay widths of X_(0)→VV are on the order of a few hundred keV,while the decay widths of X_(0)→PP can reach several MeV.The X_(0)→ρρandππhave larger decay rates.The relative width ratios between the channels are nearly model-independent.Moreover,among those channels only with isovector or isoscalar mesons,the relevant ratios are also independent of the phase angle.The predicted ratios are helpful for searching the X_(0)in the future experiments at BESIII and Belle II.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602501)the National Natural Science Foundation of China(Grant No.12011530060)+1 种基金supported solely by the Russian Science Foundation(Grant No.22-12-00043)supported by the Chinese Academy of Sciences(CAS)Presidents International Fellowship Initiative(PIFI)(Grant Nos.2018VMB0016 and 2022VMC0002),respectively。
文摘We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-lying excited states to the 1s-muon state can lead to the production of electron-positron pairs.We show that the Breit interaction determines the transition probabilities for states with nonzero orbital momentum.We show that the pair production arises mainly from the decay of the 2p states.Thus,the Breit interaction governs electron-positron pair production in bound-bound muon transitions.This process offers a unique opportunity to explore quantum electrodynamics in strong fields,as well as a class of nonradiative transitions involving electron-positron pair production.
基金supported by the National Natural Science Foundation of China(Grant Nos.12175315 and 12205385)。
文摘We propose a novel approach to generate and manipulate topological Floquet bound states in the continuum(BICs)via a class of systems constructed by coupling two identical periodically driven one-dimensional Su-Schrieffer-Heeger chains.The formation of topological Floquet BICs can be adjusted only by tuning the driving amplitude or frequency,regardless of whether the static system has BICs or not.The interchain bias can only change the localization property of topological Floquet BICs,and a bigger bias can lead to transforming topological Floquet BICs into bound states out of the continuum(BOCs).But it does not change the topological properties of these topological Floquet states.Based on the repulsion effect of edge states,we propose to detect occurrence of topological Floquet BICs and transition point between topological Floquet BICs and BOCs using quantum walk.Our work provided a convenient and realistic approach for the experimental realization and manipulation of BICs in a single-particle quantum system.
基金supported by the NSFC under Grant Nos.11374315 and 12074395the Invited Scientist Program of CNRS at Ecole Polytechnique,Palaiseau,France。
文摘The capacity to predict X-ray transition and K-edge energies in dense finite-temperatur plasmas with high precision is of primary importance for atomic physics of matter under extreme conditions.The dual characteristics of bound and continuum states in dense matter are modeled by a valence-band-like structure in a generalized ion-sphere approach with states that are either bound,free,or mixed.The self-consistent combination of this model with the Dirac wave equations of multielectron bound states allows one to fully respect the Pauli principle and to take into account the exact nonlocal exchange terms.The generalized method allows very high precision without implication of calibration shifts and scaling parameters and therefore has predictive power.This leads to new insights in the analysis of various data.The simple ionization model representing the K-edge is generalized to excitation–ionization phenomena resulting in an advanced interpretation of ionization depression data in near-solid-density plasmas.The model predicts scaling relations along the isoelectronic sequences and the existence of bound M-states that are in excellent agreement with experimental data,whereas other methods have failed.The application to unexplained data from compound materials also gives good agreement without the need to invoke any additional assumptions in the generalized model,whereas other methods have lacked consistency.
基金Sponsored by Foreign Expert Program of China(Grant No.DL2023041002L)Yulin City Industry University Research Project(Grant No.CXY-2022-59).
文摘This study mainly focuses on the triangle bounded L⁃algebras and triangle ideals.Firstly,the definition of triangle bounded L⁃algebras is presented,and several examples with different conditions are outlined along with an exploration of their properties.Moreover,we investigate the structure of triangle bounded L⁃algebra with a special condition.Secondly,we define the concept of triangle ideals of triangle bounded L⁃algebra and explore the connection between the triangle ideals of triangle bounded L⁃algebra L and the ideals of bounded L⁃algebra E(L).In addition,we classified and studied various classes of triangle ideals,including Stonean triangle ideals,extended Stonean triangle ideals,and lattice ideals,and by introducing the notion of Stonean triangle bounded L algebras,we examine the relationship between Stonean triangle bounded L⁃algebras and Stonean triangle ideals.Finally,we investigate the interrelationships among these various types of triangle ideals.
基金the National Natural Science Foundation of China(Nos.51265021 and 51965032)the Gansu Provincial Department of Education:Excellent Graduate Student“Innovation Star"Project(No.2022CXZX-571)。
文摘For the process of multi-robot collaboration to lift the same lifted object by flexible cables,the existing collision detection algorithm of cables between the environmental obstacles has the problem of misjudgment and omission.In this work,the collision detection of cable vector was studied,and the purpose of collision detection was realized by algorithm.Considering the characteristics of cables themselves,based on oriented bounding box theory,the cable optimization model and environmental obstacle model were established,and a new basic geometric collision detection model was proposed.Then a fast cable vector collision detection algorithm and an optimization principle were proposed.Finally,the rationality of the cable collision detection model and the effectiveness of the proposed algorithm were verified by simulation.Simulation results show that the proposed method can meet the requirements of the fast detection and the accuracy in complex virtual environment.The results lay a foundation for obstacle avoidance motion planning of system.
文摘Response analysis of structures involving non-probabilistic uncertain parameters can be closely related to optimization.This paper provides a review on optimization-based methods for uncertainty analysis,with focusing attention on specific properties of adopted numerical optimization approaches.We collect and discuss the methods based on nonlinear programming,semidefinite programming,mixed-integer programming,mathematical programming with complementarity constraints,difference-of-convex programming,optimization methods using surrogate models and machine learning techniques,and metaheuristics.As a closely related topic,we also overview the methods for assessing structural robustness using non-probabilistic uncertainty modeling.We conclude the paper by drawing several remarks through this review.
基金supported by the National Natural Science Foundation of China(No.52293471)National Key R&D Program of China(No.2022YFB3707303).
文摘The flocculation behavior of carbon black (CB)-filled isoprene rubber (IR) nanocomposites was systematically investigated under both dynamic and static conditions to unravel the distinct mechanisms governing filler network evolution.Under dynamic conditions,small oscillatory shear strains (0.1%) significantly enhanced filler particle motion,leading to pronounced agglomeration and a flocculation degree of about 4.3MPa at 145℃.In contrast,static flocculation exhibited a fundamentally different mechanism dominated by polymer chain dynamics,which is driven mainly by thermal activation.Radial distribution function (RDF) analysis of transmission electron microscopy (TEM) images revealed a slight decrease (2 nm) in the interparticle distance peak after static annealing at 100℃ for 7 h,indicating localized motion of CB particles.However,the overall filler network remained stable,with no significant agglomeration observed.The increase in bound rubber content from about 23% to 28% with rising temperature further confirmed the dominant role of polymer chain adsorption and interfacial reinforcement in static flocculation.These findings highlight the critical influence of external strain on filler network formation and provide new insights into the polymer-dominated mechanism of static flocculation.The results offer practical guidance for optimizing the storage and processing of rubber nanocomposites,particularly in applications where static flocculation during prolonged storage is a concern.
基金financial support from the National Natural Science Foundation of China(Grant Nos.42007251 and 42027806)the Doctoral Dissertation Cultivation Project of Northwest University(Grant No.YB2024016).
文摘Currently,Robinia pseudoacacia L.is distributed extensively across the Chinese Loess Plateau.Root exudates released by Robinia pseudoacacia L.are one of the mechanisms through which Robinia pseudoacacia L.affects soil properties.However,how root exudates influencethe hydraulic properties of soil remains unclear,especially for fine-grained soils.This knowledge gap impedes a comprehensive understanding of the function of vegetation in wastewater treatment,ecological restoration,and seepage analysis.To investigate the effect and underlying mechanisms of the root exudates of Robinia pseudoacacia L.on the saturated hydraulic conductivity of loess(a fine-grainedsoil),the saturated hydraulic conductivity,bound water content,grain size distribution,and microstructure characteristics of loess treated with root exudates at varying concentrations were determined in this study through a series of tests.The results show that the mean saturated hydraulic conductivities of the loess specimens with root exudates are all lower than those without root exudates.This phenomenon can be attributed primarily to the capacity of root exudates to directly and indirectly increase the bound water content,leading to a decrease in the effective seepage channels of the loess.For loess with/without root exudates,the variation of saturated hydraulic conductivity over time can be divided into three stages:an initial constant stage,a rapid reduction stage,and a re-stabilization stage.This is primarily attributed to the migration of particles within a specifiedsize range(7-30μm)and pore-clogging in the specimens during the seepage process.A schematic diagram is proposed for the structural evolution of fine-grained soil with or without root exudates during long-term seepage.
基金supported by the National Natural Science Foundation of China(Nos.41991330,22241602,and 42177039)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(No.GZC20232783)。
文摘Elucidation of the interactions of crop plants with clay minerals is essential for understanding the roles of clay minerals in terrestrial ecosystems.The prevailing hypothesis suggests that the physiological barriers of plant roots prevent the direct uptake of these large-size particles.However,whether crops can directly take up clay mineral particles remains unknown.Montmorillonite is a ubiquitous and important clay mineral in soil.This study used covalent fluorescence labeling and microscopic techniques to investigate the uptake and transport of montmorillonite particles by wheat(Triticum aestivum L.)in hydroponic solution,quartz sand matrix,and sandy loam soil.Additionally,the surface attachments of montmorillonite particles in xylem sap were analyzed at the nanoscale level with transmission electron microscopy and atomic force microscopy combined with infrared spectroscopy.Our results confirmed that micrometer-sized montmorillonite particles could enter the root steles of wheat seedlings from the sites of new lateral root emergence and were subsequently transported upward to the shoots and leaves through the vasculature via the transpiration stream.In this process,the surfaces of the montmorillonites adsorbed inorganic mineral nutrients and were covered by a layer of biomolecular coronas.This study reveals the potential for crop plant uptake of micrometer-sized montmorillonite particles and complements existing theories regarding the interactions of clay minerals with crop plants.Furthermore,the findings may lay a foundation for future studies on clay mineral interactions with crop plants in terrestrial ecosystems.
文摘Codebooks are widely applied in code division multiple access communication systems.Based on the subspaces of singular linear spaces over the finite fields,two classes of new codebooks are constructed.Firstly,a kind of binary codebooks are constructed by using the subspace of the singular linear space over the finite fields.According to the anzahl theorem,the parameters and the maximum correlation amplitude I_(max)(C)of the codebooks are calculated,and then given the conditions that the I_(max)(C)asymptotically reaches the Welch bound.On this basis,by mixing with Hadamard matrices,the number of columns are increased and obtain another class of new code,which further relaxes the conditions that the I_(max)(C)asymptotically reaches the Welch bound.
基金financially supported by the National Natural Science Foundation of China(Grants Nos.41877255,and 52078182).
文摘The tiered geosynthetic-reinforced soil (GRS) walls have been increasingly applied in the high and steep retaining soil structures. However, very little is known about the design method for the tiered GRS wall in practice. This study is aimed at proposing an upper-bound stability analysis method of a tiered GRS wall. The proposed method was firstly validated by the existing results from the centrifuge test and the numerical method, and then a parametric study was performed to investigate the effects of the cohesionless backfill friction angle φ1 and the wall geometric parameters including the offset distance, the total wall height, the batter angle δ, the number of tiers n, and wall height ratio of adjacent tiers on the dimensionless equivalent earth pressure coefficient KT. The analysis results demonstrated that as the φ1 increases, the shear strength of backfill is enhanced and thus the KT or the total reinforcement tensile force decreases, and the KT decreases with the increase of the offset distance at the initial stage and then becomes stable when it reaches a certain critical value. For a fixed offset distance, the KT or the total reinforcement tensile force decreases with the increase of the δ. For the two-tiered GRS walls having the offset distance less than the critical value, the wall with the smaller wall height ratio has a larger KT. Further, the variation of the location of the critical failure surfaces of tiered GRS walls was presented in this study with the variation of the φ1 and the wall geometry.
基金Supported by the Open Research Fund of Key Laboratory of Nonlinear Analysis and Applications(Central China Normal University),Ministry of Education,P.R.China(Grant No.NAA2025ORG011)Science and Technology Plan Project of Jingmen(Grant No.2024YFZD076)+3 种基金Research Team Project of Jingchu University of Technology(Grant No.TD202006)Research Project of Jingchu University of Technology(Grant Nos.HX20240049HX20240200)the Teaching Reform Research Project of Hubei Province(Grant No.2024496)。
文摘In this paper,we study the eigenvalue problem of the Markov diffusion operator L^(2),and give generalized inequalities for eigenvalues of the operator L^(2)on a Markov diffusion triple.By applying these inequalities,we then get some new universal bounds for eigenvalues of a special Markov diffusion operator L^(2)on bounded domains in an Euclidean space.Moreover,our results can reveal the relationship between the(k+1)-th eigenvalue and the first k eigenvalues in a relatively straightforward manner.
基金Supported by the National Natural Science Foundation of China(12201446)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(22KJB110005)the Shuangchuang Program of Jiangsu Province(JSSCBS20220898)。
文摘It is known that monotone recurrence relations can induce a class of twist homeomorphisms on the high-dimensional cylinder,which is an extension of the class of monotone twist maps on the annulus or two-dimensional cylinder.By constructing a bounded solution of the monotone recurrence relation,the main conclusion in this paper is acquired:The induced homeomorphism has Birkhoff orbits provided there is a compact forward-invariant set.Therefore,it generalizes Angenent's results in low-dimensional cases.
