In recent years,there has been a surge of interest in higher-order topological phases(HOTPs)across various disciplines within the field of physics.These unique phases are characterized by their ability to harbor topol...In recent years,there has been a surge of interest in higher-order topological phases(HOTPs)across various disciplines within the field of physics.These unique phases are characterized by their ability to harbor topological protected boundary states at lower-dimensional boundaries,a distinguishing feature that sets them apart from conventional topological phases and is attributed to the higher-order bulk-boundary correspondence.Two-dimensional(2D)twisted systems offer an optimal platform for investigating HOTPs,owing to their strong controllability and experimental feasibility.Here,we provide a comprehensive overview of the latest research advancements on HOTPs in 2D twisted multilayer systems.We will mainly review the HOTPs in electronic,magnonic,acoustic,photonic and mechanical twisted systems,and finally provide a perspective of this topic.展开更多
Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics...Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics,and free electron radiation devices.Particularly,they are promising platforms for studying thermionic emission.It is illustrated that using vdW heterostructure-based thermionic emission can enhance heat transfer in vacuum devices.As a proof of concept,the approach is demonstrated to offer a promising solution for the long-standing overheating issue in X-ray tubes.Specifically,it is shown that the saturated target temperature of a 2000 W X-ray tube can be reduced from around 1200℃ to 490℃.Additionally,it is also demonstrated that by reducing the height of the Schottky barrier formed in the vdW heterostructures,the thermionic cooling performance can be enhanced.The findings pave the way for the development of high-power X-ray tubes.展开更多
Helsmoortel-Van der Aa综合征(HVDAS)是一种罕见的神经发育障碍性疾病,主要由活性依赖性神经保护蛋白(ADNP)基因突变引起,是最常见的孤独症谱系障碍(ASD)单基因病因之一。本文分析2024年就诊于海口市妇幼保健院的1例患儿,男,3岁10个月...Helsmoortel-Van der Aa综合征(HVDAS)是一种罕见的神经发育障碍性疾病,主要由活性依赖性神经保护蛋白(ADNP)基因突变引起,是最常见的孤独症谱系障碍(ASD)单基因病因之一。本文分析2024年就诊于海口市妇幼保健院的1例患儿,男,3岁10个月,因“运动、语言发育迟缓2年余,社交障碍1年余”入院,检查发现患儿存在孤独症谱系障碍、全面发育迟缓、特殊面容、矮小、脑积水等临床表现,基因检测发现患儿携带ADNP基因杂合突变{NM_001282531.3(ADNP):c.2189(exon6)delG[p.(Arg730Glnfs3)]},其父母及妹妹均未携带该突变。总结临床资料并结合文献复习,ADNP基因在染色质重塑和神经发育障碍中发挥重要作用,ADNP基因突变可累及多系统。此例HVDAS具有典型临床表现,并拓宽了脑积水的表型谱,为此类基因变异的遗传咨询以及临床医师的早期识别提供了参考依据。展开更多
The Chebyshev polynomial approximation is applied to investigate the stochastic period-doubling bifurcation and chaos problems of a stochastic Duffing-van der Pol system with bounded random parameter of exponential pr...The Chebyshev polynomial approximation is applied to investigate the stochastic period-doubling bifurcation and chaos problems of a stochastic Duffing-van der Pol system with bounded random parameter of exponential probability density function subjected to a harmonic excitation. Firstly the stochastic system is reduced into its equivalent deterministic one, and then the responses of stochastic system can be obtained by numerical methods. Nonlinear dynamical behaviour related to stochastic period-doubling bifurcation and chaos in the stochastic system is explored. Numerical simulations show that similar to its counterpart in deterministic nonlinear system of stochastic period-doubling bifurcation and chaos may occur in the stochastic Duffing-van der Pol system even for weak intensity of random parameter. Simply increasing the intensity of the random parameter may result in the period-doubling bifurcation which is absent from the deterministic system.展开更多
This paper applies washout filter technology to amplitude control of limit cycles emerging from Hopf bifurcation of the van der Pol-Duffing system. The controlling parameters for the appearance of Hopf bifurcation are...This paper applies washout filter technology to amplitude control of limit cycles emerging from Hopf bifurcation of the van der Pol-Duffing system. The controlling parameters for the appearance of Hopf bifurcation are given by the Routh-Hurwitz criteria. Noticeably, numerical simulation indicates that the controllers control the amplitude of limit cycles not only of the weakly nonlinear van der Pol-Duffing system but also of the strongly nonlinear van der Pol-Duffing system. In particular, the emergence of Hopf bifurcation can be controlled by a suitable choice of controlling parameters. Gain-amplitude curves of controlled systems are also drawn.展开更多
In this paper, the Chebyshev polynomial approximation is applied to the problem of stochastic period-doubling bifurcation of a stochastic Bonhoeffer-van der Pol （BVP for short） system with a bounded random parameter...In this paper, the Chebyshev polynomial approximation is applied to the problem of stochastic period-doubling bifurcation of a stochastic Bonhoeffer-van der Pol （BVP for short） system with a bounded random parameter. In the analysis, the stochastic BVP system is transformed by the Chebyshev polynomial approximation into an equivalent deterministic system, whose response can be readily obtained by conventional numerical methods. In this way we have explored plenty of stochastic period-doubling bifurcation phenomena of the stochastic BVP system. The numerical simulations show that the behaviour of the stochastic period-doubling bifurcation in the stochastic BVP system is by and large similar to that in the deterministic mean-parameter BVP system, but there are still some featured differences between them. For example, in the stochastic dynamic system the period-doubling bifurcation point diffuses into a critical interval and the location of the critical interval shifts with the variation of intensity of the random parameter. The obtained results show that Chebyshev polynomial approximation is an effective approach to dynamical problems in some typical nonlinear systems with a bounded random parameter of an arch-like probability density function.展开更多
Bifurcation properties of a Duffing-van der Pol system with two parameters under multi-frequency excitations are studied. Three cases are discussed： （1） λ 1 is considered as bifurcation parameter, （2） λ 2 is co...Bifurcation properties of a Duffing-van der Pol system with two parameters under multi-frequency excitations are studied. Three cases are discussed： （1） λ 1 is considered as bifurcation parameter, （2） λ 2 is considered as bifurcation parameter, and （3） λ 1 and λ 2 are both considered as bifurcation parameters. According to the definition of transition sets, the whole parametric space is divided into several different persistent regions by the transition sets for different cases. The bifurcation diagrams in different persistent regions are obtained, which provides a theoretical basis for optimal design of the system.展开更多
Helsmoortel-Van der Aa综合征(HVDAS),是一种罕见的神经发育障碍疾病,主要由功能活性依赖神经保护蛋白(ADNP)基因突变引起。该文回顾性分析了就诊于济宁医学院附属医院的1例HVDAS患儿,系1岁3个月男性幼儿,其存在运动、语言、智力发育...Helsmoortel-Van der Aa综合征(HVDAS),是一种罕见的神经发育障碍疾病,主要由功能活性依赖神经保护蛋白(ADNP)基因突变引起。该文回顾性分析了就诊于济宁医学院附属医院的1例HVDAS患儿,系1岁3个月男性幼儿,其存在运动、语言、智力发育障碍及孤独症样刻板行为,有行为问题,外貌畸形,视力异常,反复呼吸道感染等临床表现,基因检测发现患儿携带ADNP基因杂合突变c.2157C>A(p.Tyr719Ter),其父母均未携带该突变。因此,提示临床工作者要加强对该疾病的认识,做到早发现、早治疗,以积极干预,从而提高患儿的生活质量。展开更多
This paper proposes an impulsive control scheme for chaotic systems consisting of Van der Pol oscillators coupled to linear oscillators （VDPL） based on their Takagi-Sugeno （T-S） fuzzy models. A T-S fuzzy model is ...This paper proposes an impulsive control scheme for chaotic systems consisting of Van der Pol oscillators coupled to linear oscillators （VDPL） based on their Takagi-Sugeno （T-S） fuzzy models. A T-S fuzzy model is utilized to represent the chaotic VDPL system. By using comparison method, a general asymptotical stability criterion by means of linear matrix inequality （LMI） is derived for the T-S fuzzy model of VDPL system with impulsive effects. The simulation results demonstrate the effectiveness of the proposed scheme.展开更多
各种微型电子元件在发展过程中逐渐对供电的免维护性提出了更高的要求,且用电器所在的环境中存在着天然的振动能量,收集振动能量进行供电是替代传统能源的有效途径之一.目前振动能量采集技术主要集中于粘性阻尼的采集系统,而van der Po...各种微型电子元件在发展过程中逐渐对供电的免维护性提出了更高的要求,且用电器所在的环境中存在着天然的振动能量,收集振动能量进行供电是替代传统能源的有效途径之一.目前振动能量采集技术主要集中于粘性阻尼的采集系统,而van der Pol阻尼在电子工程、气动力学、生物学等领域有着广泛的应用,但有关van der Pol阻尼振动能量采集系统的工作少有报道.本文研究了van der Pol阻尼下三稳态能量采集器对于低频外部激励的簇发振荡现象和采集性能.运用快慢分析法,分析了系统的簇发振荡机理,观察到了极限环的分岔.采用数值方法,通过转换相图,验证了系统在不同频率比下的分岔机理.根据系统响应的时间历程,发现了大幅度的簇发振荡和较高的稳定电压响应.最后,计算了系统在不同频率比的外部激励下的平均输出电压,与粘性阻尼系统进行了对比,结果表明van der Pol阻尼下三稳态能量采集器具有更高的采集性能.此外,还比较了不同阻尼对输出电能的影响,并讨论了最优输出功率.展开更多
本文报道1例ADNP基因新发杂合变异Helsmoortel-Van der Aa综合征病例。该患儿为1岁6月男童,存在有特殊面容、智力发育低下、运动、语言发育迟缓、小手等临床表现,基因分析显示患儿ADNP基因有一个新发变异位点C.460_461insAA(p.P154Qfs*...本文报道1例ADNP基因新发杂合变异Helsmoortel-Van der Aa综合征病例。该患儿为1岁6月男童,存在有特殊面容、智力发育低下、运动、语言发育迟缓、小手等临床表现,基因分析显示患儿ADNP基因有一个新发变异位点C.460_461insAA(p.P154Qfs*7),为移码突变。Helsmoortel-Van der Aa综合征可累及多系统,基因检测有助于诊断。展开更多
The aim of this work is to prove the existence for the global solution of a nonisothermal or non-isentropic model of capillary compressible fluids derived by J.E.Dunn and J.Serrin(1985),in the case of van der Waals ga...The aim of this work is to prove the existence for the global solution of a nonisothermal or non-isentropic model of capillary compressible fluids derived by J.E.Dunn and J.Serrin(1985),in the case of van der Waals gas.Under the small initial perturbation,the proof of the global existence is based on an elementary energy method using the continuation argument of local solution.Moreover,the uniqueness of global solutions and large time behavior of the density are given.It is one of the main difficulties that the pressure p is not the increasing function of the densityρ.展开更多
The drive for efficient thermal management has intensified with the miniaturization of electronic devices.This study explores the modulation of phonon transport within graphene by introducing silicon nanoparticles inf...The drive for efficient thermal management has intensified with the miniaturization of electronic devices.This study explores the modulation of phonon transport within graphene by introducing silicon nanoparticles influenced by van der Waals forces.Our approach involves the application of non-equilibrium molecular dynamics to assess thermal conductivity while varying the interaction strength,leading to a noteworthy reduction in thermal conductivity.Furthermore,we observe a distinct attenuation in length-dependent behavior within the graphene-nanoparticles system.Our exploration combines wave packet simulations with phonon transmission calculations,aligning with a comprehensive analysis of the phonon transport regime to unveil the underlying physical mechanisms at play.Lastly,we conduct transient molecular dynamics simulations to investigate interfacial thermal conductance between the nanoparticles and the graphene,revealing an enhanced thermal boundary conductance.This research not only contributes to our understanding of phonon transport but also opens a new degree of freedom for utilizing van der Waals nanoparticle-induced resonance,offering promising avenues for the modulation of thermal properties in advanced materials and enhancing their performance in various technological applications.展开更多
In this paper we transfer the van der Waerden problem into a problem of solving special systems of equations and give some properties of the solutions for the systems.
The present study is related to design a stochastic framework for the numerical treatment of the Van der Pol heartbeat model(VP-HBM)using the feedforward artificial neural networks(ANNs)under the optimization of parti...The present study is related to design a stochastic framework for the numerical treatment of the Van der Pol heartbeat model(VP-HBM)using the feedforward artificial neural networks(ANNs)under the optimization of particle swarm optimization(PSO)hybridized with the active-set algorithm(ASA),i.e.,ANNs-PSO-ASA.The global search PSO scheme and local refinement of ASA are used as an optimization procedure in this study.An error-based merit function is defined using the differential VP-HBM form as well as the initial conditions.The optimization of the merit function is accomplished using the hybrid computing performances of PSO-ASA.The designed performance of ANNs-PSO-ASA is implemented for the numerical treatment of the VP-HBM dynamics by fluctuating the pulse shape adjustment terms,external forcing factor and damping coefficient with fixed ventricular contraction period.To perform the correctness of the present scheme,the obtained numerical results through the designed ANN-PSO-ASA will be compared with the Adams numerical method.The statistical investigations with larger dataset are provided using the“mean absolute deviation”,“Theil’s inequality coefficient”and“variance account for”operators to perform the applicability,reliability,and effectiveness of the designed ANNs-PSO-ASA scheme for solving the VP-HBM.展开更多
为深入了解Bonhoeffer-van der Pol系统在随机激励下系统动力学行为的演化规律,研究了随机Bonhoeffer-van der Pol系统的稳态响应和随机分岔。借助路径积分方法、高斯闭合方法和蒙特卡洛模拟等,求解了噪声激励下Bonhoeffer-van der Pol...为深入了解Bonhoeffer-van der Pol系统在随机激励下系统动力学行为的演化规律,研究了随机Bonhoeffer-van der Pol系统的稳态响应和随机分岔。借助路径积分方法、高斯闭合方法和蒙特卡洛模拟等,求解了噪声激励下Bonhoeffer-van der Pol系统的平稳解,发现系统参数诱导的随机P-分岔(唯像分岔)现象。通过与蒙特卡洛模拟结果的对比,验证了所述路径积分方法的准确性。展开更多
It is important to study the propagation and interaction of progressing waves of nonlinear equations in the class of piecewise smooth function. However, there has not been many works on that in multidimensional case. ...It is important to study the propagation and interaction of progressing waves of nonlinear equations in the class of piecewise smooth function. However, there has not been many works on that in multidimensional case. In 1985, J, Rauch & M. Reed have provad the existence and uniqueness of piecewise smooth solution for展开更多
As a typical in-memory computing hardware design, nonvolatile ternary content-addressable memories(TCAMs) enable the logic operation and data storage for high throughout in parallel big data processing. However,TCAM c...As a typical in-memory computing hardware design, nonvolatile ternary content-addressable memories(TCAMs) enable the logic operation and data storage for high throughout in parallel big data processing. However,TCAM cells based on conventional silicon-based devices suffer from structural complexity and large footprintlimitations. Here, we demonstrate an ultrafast nonvolatile TCAM cell based on the MoTe2/hBN/multilayergraphene (MLG) van der Waals heterostructure using a top-gated partial floating-gate field-effect transistor(PFGFET) architecture. Based on its ambipolar transport properties, the carrier type in the source/drain andcentral channel regions of the MoTe2 channel can be efficiently tuned by the control gate and top gate, respectively,enabling the reconfigurable operation of the device in either memory or FET mode. When working inthe memory mode, it achieves an ultrafast 60 ns programming/erase speed with a current on-off ratio of ∼105,excellent retention capability, and robust endurance. When serving as a reconfigurable transistor, unipolar p-typeand n-type FETs are obtained by adopting ultrafast 60 ns control-gate voltage pulses with different polarities.The monolithic integration of memory and logic within a single device enables the content-addressable memory(CAM) functionality. Finally, by integrating two PFGFETs in parallel, a TCAM cell with a high current ratioof ∼10^(5) between the match and mismatch states is achieved without requiring additional peripheral circuitry.These results provide a promising route for the design of high-performance TCAM devices for future in-memorycomputing applications.展开更多
The rise of smart wearable devices has driven the demand for flexible,high-performance optoelectronic devices with low power and easy high-density integration.Emerging Two-dimensional(2D)materials offer promising solu...The rise of smart wearable devices has driven the demand for flexible,high-performance optoelectronic devices with low power and easy high-density integration.Emerging Two-dimensional(2D)materials offer promising solutions.However,the use of 3D metal in traditional 2D devices often leads to Fermi-level pinning,compromising device performance.2D metallic materials,such as graphene and 2H-phase NbSe_(2),present a new avenue for addressing this issue and constructing high-performance,low-power photodetectors.In this work,we designed an all-2D asymmetric contacts photodetector using Gr and NbSe_(2)as electrodes for the 2D semiconductor WSe_(2).The asymmetric Schottky barriers and built-in electric fields facilitated by this architecture resulted in outstanding photovoltaic characteristics and self-powered photodetection.Under zero bias,the device exhibited a responsivity of 287 mA/W,a specific detectivity of 5.3×10^(11)Jones,and an external quantum efficiency of 88%.It also demonstrated an ultra-high light on/offratio(1.8×10^(5)),ultra-fast photoresponse speeds(80/72μs),broad-spectrum responsiveness(405980 nm),and exceptional cycling stability.The applications of the Gr/WSe_(2)/NbSe_(2)heterojunction in imaging and infrared optical communication have been explored,underscoring its significant potential.This work offers an idea to construct all-2D ultrathin optoelectronic devices.展开更多
The magnons(the quanta of collective spin-wave excitations)in two-dimensional van der Waals(vd W)magnets exhibit some intriguing characteristics,such as spin Nernst effect,topological magnons,Weyl magnons,moiréma...The magnons(the quanta of collective spin-wave excitations)in two-dimensional van der Waals(vd W)magnets exhibit some intriguing characteristics,such as spin Nernst effect,topological magnons,Weyl magnons,moirémagnons,magnon valley Hall effect,etc.,and can be regulated through approaches such as stacking,electric doping,pressure,strain and twisting,opening unprecedented avenues to explore fundamental magnetic physics and spin-based technologies.Over the past few years,intense research efforts have been invested in unraveling magnon properties in vd W materials.This review comprehensively summarizes recent advancements in understanding magnons in vd W magnetic systems,spanning fundamental theories and experimental frontiers.It also introduces the experimental techniques widely used in this field,including inelastic neutron scattering,Raman/Brillouin spectroscopy,time-resolved spectroscopy and inelastic magnetotunneling spectroscopy,and discusses the coupling between magnons and other excitations,such as phonons and excitons.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12304539,12074108,12474151,12347101)the Natural Science Foundation of Chongqing(Grant No.CSTB2022NSCQ-MSX0568)Beijing National Laboratory for Condensed Matter Physics(Grant No.2024BNLCMPKF025)。
文摘In recent years,there has been a surge of interest in higher-order topological phases(HOTPs)across various disciplines within the field of physics.These unique phases are characterized by their ability to harbor topological protected boundary states at lower-dimensional boundaries,a distinguishing feature that sets them apart from conventional topological phases and is attributed to the higher-order bulk-boundary correspondence.Two-dimensional(2D)twisted systems offer an optimal platform for investigating HOTPs,owing to their strong controllability and experimental feasibility.Here,we provide a comprehensive overview of the latest research advancements on HOTPs in 2D twisted multilayer systems.We will mainly review the HOTPs in electronic,magnonic,acoustic,photonic and mechanical twisted systems,and finally provide a perspective of this topic.
基金supported by National Natural Science Foundation of China(61921002 and 92163204)。
文摘Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics,and free electron radiation devices.Particularly,they are promising platforms for studying thermionic emission.It is illustrated that using vdW heterostructure-based thermionic emission can enhance heat transfer in vacuum devices.As a proof of concept,the approach is demonstrated to offer a promising solution for the long-standing overheating issue in X-ray tubes.Specifically,it is shown that the saturated target temperature of a 2000 W X-ray tube can be reduced from around 1200℃ to 490℃.Additionally,it is also demonstrated that by reducing the height of the Schottky barrier formed in the vdW heterostructures,the thermionic cooling performance can be enhanced.The findings pave the way for the development of high-power X-ray tubes.
文摘Helsmoortel-Van der Aa综合征(HVDAS)是一种罕见的神经发育障碍性疾病,主要由活性依赖性神经保护蛋白(ADNP)基因突变引起,是最常见的孤独症谱系障碍(ASD)单基因病因之一。本文分析2024年就诊于海口市妇幼保健院的1例患儿,男,3岁10个月,因“运动、语言发育迟缓2年余,社交障碍1年余”入院,检查发现患儿存在孤独症谱系障碍、全面发育迟缓、特殊面容、矮小、脑积水等临床表现,基因检测发现患儿携带ADNP基因杂合突变{NM_001282531.3(ADNP):c.2189(exon6)delG[p.(Arg730Glnfs3)]},其父母及妹妹均未携带该突变。总结临床资料并结合文献复习,ADNP基因在染色质重塑和神经发育障碍中发挥重要作用,ADNP基因突变可累及多系统。此例HVDAS具有典型临床表现,并拓宽了脑积水的表型谱,为此类基因变异的遗传咨询以及临床医师的早期识别提供了参考依据。
基金Project supported by the National Natural Science Foundation of China （Grants Nos 10472091 and 10332030）.
文摘The Chebyshev polynomial approximation is applied to investigate the stochastic period-doubling bifurcation and chaos problems of a stochastic Duffing-van der Pol system with bounded random parameter of exponential probability density function subjected to a harmonic excitation. Firstly the stochastic system is reduced into its equivalent deterministic one, and then the responses of stochastic system can be obtained by numerical methods. Nonlinear dynamical behaviour related to stochastic period-doubling bifurcation and chaos in the stochastic system is explored. Numerical simulations show that similar to its counterpart in deterministic nonlinear system of stochastic period-doubling bifurcation and chaos may occur in the stochastic Duffing-van der Pol system even for weak intensity of random parameter. Simply increasing the intensity of the random parameter may result in the period-doubling bifurcation which is absent from the deterministic system.
基金Project supported by the National Natural Science Foundation of China (Grant No 10672053)
文摘This paper applies washout filter technology to amplitude control of limit cycles emerging from Hopf bifurcation of the van der Pol-Duffing system. The controlling parameters for the appearance of Hopf bifurcation are given by the Routh-Hurwitz criteria. Noticeably, numerical simulation indicates that the controllers control the amplitude of limit cycles not only of the weakly nonlinear van der Pol-Duffing system but also of the strongly nonlinear van der Pol-Duffing system. In particular, the emergence of Hopf bifurcation can be controlled by a suitable choice of controlling parameters. Gain-amplitude curves of controlled systems are also drawn.
基金Project supported by the Major Program of the National Natural Science Foundation of China, China （Grant No 10332030）, the National Natural Science Foundation of China （Grant No 10472091）, and the Graduate Starting Seed Fund of Northwestern Polytechnical University, China （Grant No Z200655）.
文摘In this paper, the Chebyshev polynomial approximation is applied to the problem of stochastic period-doubling bifurcation of a stochastic Bonhoeffer-van der Pol （BVP for short） system with a bounded random parameter. In the analysis, the stochastic BVP system is transformed by the Chebyshev polynomial approximation into an equivalent deterministic system, whose response can be readily obtained by conventional numerical methods. In this way we have explored plenty of stochastic period-doubling bifurcation phenomena of the stochastic BVP system. The numerical simulations show that the behaviour of the stochastic period-doubling bifurcation in the stochastic BVP system is by and large similar to that in the deterministic mean-parameter BVP system, but there are still some featured differences between them. For example, in the stochastic dynamic system the period-doubling bifurcation point diffuses into a critical interval and the location of the critical interval shifts with the variation of intensity of the random parameter. The obtained results show that Chebyshev polynomial approximation is an effective approach to dynamical problems in some typical nonlinear systems with a bounded random parameter of an arch-like probability density function.
基金Project supported by the National Natural Science Foundation of China (No. 10632040)
文摘Bifurcation properties of a Duffing-van der Pol system with two parameters under multi-frequency excitations are studied. Three cases are discussed： （1） λ 1 is considered as bifurcation parameter, （2） λ 2 is considered as bifurcation parameter, and （3） λ 1 and λ 2 are both considered as bifurcation parameters. According to the definition of transition sets, the whole parametric space is divided into several different persistent regions by the transition sets for different cases. The bifurcation diagrams in different persistent regions are obtained, which provides a theoretical basis for optimal design of the system.
文摘Helsmoortel-Van der Aa综合征(HVDAS),是一种罕见的神经发育障碍疾病,主要由功能活性依赖神经保护蛋白(ADNP)基因突变引起。该文回顾性分析了就诊于济宁医学院附属医院的1例HVDAS患儿,系1岁3个月男性幼儿,其存在运动、语言、智力发育障碍及孤独症样刻板行为,有行为问题,外貌畸形,视力异常,反复呼吸道感染等临床表现,基因检测发现患儿携带ADNP基因杂合突变c.2157C>A(p.Tyr719Ter),其父母均未携带该突变。因此,提示临床工作者要加强对该疾病的认识,做到早发现、早治疗,以积极干预,从而提高患儿的生活质量。
文摘This paper proposes an impulsive control scheme for chaotic systems consisting of Van der Pol oscillators coupled to linear oscillators （VDPL） based on their Takagi-Sugeno （T-S） fuzzy models. A T-S fuzzy model is utilized to represent the chaotic VDPL system. By using comparison method, a general asymptotical stability criterion by means of linear matrix inequality （LMI） is derived for the T-S fuzzy model of VDPL system with impulsive effects. The simulation results demonstrate the effectiveness of the proposed scheme.
文摘各种微型电子元件在发展过程中逐渐对供电的免维护性提出了更高的要求,且用电器所在的环境中存在着天然的振动能量,收集振动能量进行供电是替代传统能源的有效途径之一.目前振动能量采集技术主要集中于粘性阻尼的采集系统,而van der Pol阻尼在电子工程、气动力学、生物学等领域有着广泛的应用,但有关van der Pol阻尼振动能量采集系统的工作少有报道.本文研究了van der Pol阻尼下三稳态能量采集器对于低频外部激励的簇发振荡现象和采集性能.运用快慢分析法,分析了系统的簇发振荡机理,观察到了极限环的分岔.采用数值方法,通过转换相图,验证了系统在不同频率比下的分岔机理.根据系统响应的时间历程,发现了大幅度的簇发振荡和较高的稳定电压响应.最后,计算了系统在不同频率比的外部激励下的平均输出电压,与粘性阻尼系统进行了对比,结果表明van der Pol阻尼下三稳态能量采集器具有更高的采集性能.此外,还比较了不同阻尼对输出电能的影响,并讨论了最优输出功率.
文摘本文报道1例ADNP基因新发杂合变异Helsmoortel-Van der Aa综合征病例。该患儿为1岁6月男童,存在有特殊面容、智力发育低下、运动、语言发育迟缓、小手等临床表现,基因分析显示患儿ADNP基因有一个新发变异位点C.460_461insAA(p.P154Qfs*7),为移码突变。Helsmoortel-Van der Aa综合征可累及多系统,基因检测有助于诊断。
文摘The aim of this work is to prove the existence for the global solution of a nonisothermal or non-isentropic model of capillary compressible fluids derived by J.E.Dunn and J.Serrin(1985),in the case of van der Waals gas.Under the small initial perturbation,the proof of the global existence is based on an elementary energy method using the continuation argument of local solution.Moreover,the uniqueness of global solutions and large time behavior of the density are given.It is one of the main difficulties that the pressure p is not the increasing function of the densityρ.
基金funded in parts by the National Natural Science Foundation of China (Grant No.12105242)Yunnan Fundamental Research Project (Grant Nos.202201AT070161 and 202301AW070006)support from the Graduate Scientific Research and Innovation Fund of Yunnan University (Grant No.KC-22221060)。
文摘The drive for efficient thermal management has intensified with the miniaturization of electronic devices.This study explores the modulation of phonon transport within graphene by introducing silicon nanoparticles influenced by van der Waals forces.Our approach involves the application of non-equilibrium molecular dynamics to assess thermal conductivity while varying the interaction strength,leading to a noteworthy reduction in thermal conductivity.Furthermore,we observe a distinct attenuation in length-dependent behavior within the graphene-nanoparticles system.Our exploration combines wave packet simulations with phonon transmission calculations,aligning with a comprehensive analysis of the phonon transport regime to unveil the underlying physical mechanisms at play.Lastly,we conduct transient molecular dynamics simulations to investigate interfacial thermal conductance between the nanoparticles and the graphene,revealing an enhanced thermal boundary conductance.This research not only contributes to our understanding of phonon transport but also opens a new degree of freedom for utilizing van der Waals nanoparticle-induced resonance,offering promising avenues for the modulation of thermal properties in advanced materials and enhancing their performance in various technological applications.
文摘In this paper we transfer the van der Waerden problem into a problem of solving special systems of equations and give some properties of the solutions for the systems.
基金This research received funding support from the NSRF via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(Grant Number B05F640088).
文摘The present study is related to design a stochastic framework for the numerical treatment of the Van der Pol heartbeat model(VP-HBM)using the feedforward artificial neural networks(ANNs)under the optimization of particle swarm optimization(PSO)hybridized with the active-set algorithm(ASA),i.e.,ANNs-PSO-ASA.The global search PSO scheme and local refinement of ASA are used as an optimization procedure in this study.An error-based merit function is defined using the differential VP-HBM form as well as the initial conditions.The optimization of the merit function is accomplished using the hybrid computing performances of PSO-ASA.The designed performance of ANNs-PSO-ASA is implemented for the numerical treatment of the VP-HBM dynamics by fluctuating the pulse shape adjustment terms,external forcing factor and damping coefficient with fixed ventricular contraction period.To perform the correctness of the present scheme,the obtained numerical results through the designed ANN-PSO-ASA will be compared with the Adams numerical method.The statistical investigations with larger dataset are provided using the“mean absolute deviation”,“Theil’s inequality coefficient”and“variance account for”operators to perform the applicability,reliability,and effectiveness of the designed ANNs-PSO-ASA scheme for solving the VP-HBM.
文摘为深入了解Bonhoeffer-van der Pol系统在随机激励下系统动力学行为的演化规律,研究了随机Bonhoeffer-van der Pol系统的稳态响应和随机分岔。借助路径积分方法、高斯闭合方法和蒙特卡洛模拟等,求解了噪声激励下Bonhoeffer-van der Pol系统的平稳解,发现系统参数诱导的随机P-分岔(唯像分岔)现象。通过与蒙特卡洛模拟结果的对比,验证了所述路径积分方法的准确性。
基金This paper is supported by the National Foundations.
文摘It is important to study the propagation and interaction of progressing waves of nonlinear equations in the class of piecewise smooth function. However, there has not been many works on that in multidimensional case. In 1985, J, Rauch & M. Reed have provad the existence and uniqueness of piecewise smooth solution for
基金supported by the National Key Research&Development Projects of China(Grant No.2022YFA1204100)National Natural Science Foundation of China(Grant No.62488201)+1 种基金CAS Project for Young Scientists in Basic Research(YSBR-003)the Innovation Program of Quantum Science and Technology(2021ZD0302700)。
文摘As a typical in-memory computing hardware design, nonvolatile ternary content-addressable memories(TCAMs) enable the logic operation and data storage for high throughout in parallel big data processing. However,TCAM cells based on conventional silicon-based devices suffer from structural complexity and large footprintlimitations. Here, we demonstrate an ultrafast nonvolatile TCAM cell based on the MoTe2/hBN/multilayergraphene (MLG) van der Waals heterostructure using a top-gated partial floating-gate field-effect transistor(PFGFET) architecture. Based on its ambipolar transport properties, the carrier type in the source/drain andcentral channel regions of the MoTe2 channel can be efficiently tuned by the control gate and top gate, respectively,enabling the reconfigurable operation of the device in either memory or FET mode. When working inthe memory mode, it achieves an ultrafast 60 ns programming/erase speed with a current on-off ratio of ∼105,excellent retention capability, and robust endurance. When serving as a reconfigurable transistor, unipolar p-typeand n-type FETs are obtained by adopting ultrafast 60 ns control-gate voltage pulses with different polarities.The monolithic integration of memory and logic within a single device enables the content-addressable memory(CAM) functionality. Finally, by integrating two PFGFETs in parallel, a TCAM cell with a high current ratioof ∼10^(5) between the match and mismatch states is achieved without requiring additional peripheral circuitry.These results provide a promising route for the design of high-performance TCAM devices for future in-memorycomputing applications.
基金Liming Gao acknowledges funding from the National Natural Science Foundation of China(No.61727805).
文摘The rise of smart wearable devices has driven the demand for flexible,high-performance optoelectronic devices with low power and easy high-density integration.Emerging Two-dimensional(2D)materials offer promising solutions.However,the use of 3D metal in traditional 2D devices often leads to Fermi-level pinning,compromising device performance.2D metallic materials,such as graphene and 2H-phase NbSe_(2),present a new avenue for addressing this issue and constructing high-performance,low-power photodetectors.In this work,we designed an all-2D asymmetric contacts photodetector using Gr and NbSe_(2)as electrodes for the 2D semiconductor WSe_(2).The asymmetric Schottky barriers and built-in electric fields facilitated by this architecture resulted in outstanding photovoltaic characteristics and self-powered photodetection.Under zero bias,the device exhibited a responsivity of 287 mA/W,a specific detectivity of 5.3×10^(11)Jones,and an external quantum efficiency of 88%.It also demonstrated an ultra-high light on/offratio(1.8×10^(5)),ultra-fast photoresponse speeds(80/72μs),broad-spectrum responsiveness(405980 nm),and exceptional cycling stability.The applications of the Gr/WSe_(2)/NbSe_(2)heterojunction in imaging and infrared optical communication have been explored,underscoring its significant potential.This work offers an idea to construct all-2D ultrathin optoelectronic devices.
基金the Chinese Academy of Sciences—the Scientific and the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-120)the National Science Foundation of China(Grant No.NSFC12525405)。
文摘The magnons(the quanta of collective spin-wave excitations)in two-dimensional van der Waals(vd W)magnets exhibit some intriguing characteristics,such as spin Nernst effect,topological magnons,Weyl magnons,moirémagnons,magnon valley Hall effect,etc.,and can be regulated through approaches such as stacking,electric doping,pressure,strain and twisting,opening unprecedented avenues to explore fundamental magnetic physics and spin-based technologies.Over the past few years,intense research efforts have been invested in unraveling magnon properties in vd W materials.This review comprehensively summarizes recent advancements in understanding magnons in vd W magnetic systems,spanning fundamental theories and experimental frontiers.It also introduces the experimental techniques widely used in this field,including inelastic neutron scattering,Raman/Brillouin spectroscopy,time-resolved spectroscopy and inelastic magnetotunneling spectroscopy,and discusses the coupling between magnons and other excitations,such as phonons and excitons.
