The internal structure of the inertial measurement unit(IMU)in active state is easily damaged in the high overload environment.So that the IMU is usually required to be powered within the disappearance of the high ove...The internal structure of the inertial measurement unit(IMU)in active state is easily damaged in the high overload environment.So that the IMU is usually required to be powered within the disappearance of the high overload.In this paper,a mechanical switch is designed to enable the IMU based on the analysis of the impact of high overload on the power-supply circuit.In which,parameters of mechanical switch are determined through theoretical calculation and data analysis.The innovation of the proposed structure lies in that the mechanical switch is triggered through the high overload process and could provide a delay signal for the circuit.After all,the proposed switch is tested through mechanical simulation,impact test and practical test.The experimental results show that the designed mechanical switch can effectively and reliably provide the delay for the circuit and guarantee operation of the IMU under high overload.展开更多
Fast mechanical switches(FMSs)are critical components of DC circuit breakers(DCCBs),which require the switch action time to break to a sufficient distance within 3 ms in the DC line breaking scenario,while ensuring a ...Fast mechanical switches(FMSs)are critical components of DC circuit breakers(DCCBs),which require the switch action time to break to a sufficient distance within 3 ms in the DC line breaking scenario,while ensuring a long service life.The breaking mechanism significantly affects the current interruption capability of DCCBs.The operation of the repulsion mechanism,along with the morphology of the arc and its transformation within the interrupter chamber,collectively influence the breaking performance of the FMSs.This paper presents a comprehensive analysis of the FMSs,which serves as the pivotal component of controlled resonance combination circuit breakers(CRCBs).This study establishes a multi physics coupling simulation analysis method based on the equivalent circuit of repulsion mechanism discharge,combined with electromagnetic and solid mechanics fields.By constructing a full cycle magnetohydrodynamic particle arc(MHP)model and using a combined simulation of Finite Element joint model(FEJM),the evolution law of arc characteristics during the superimposed current interruption process was systematically explored.The focus was on analysing the physical process of the zero zone of the superimposed arc,the multi physics field coupling relationship of the arc,and the interaction mechanism with external characteristic parameters.Further combining with optimisation design methods,the effectiveness of the model was verified through experiments,FEJM provides comprehensive technical support for effectively reflecting the stress issues of core components during the breaking process of FMS and can provide accurate theoretical references for the optimisation design of mechanical motion components in FMS.It also accurately represents the arc extinguishing process during the breaking of FMS and provides a convenient method for the selection and design of circuit parameters for the entire circuit breaker.展开更多
This article investigates the anti-disturbance and stabilization problems for the nonlinear uncertain permanent magnet synchronous motor(PMSM)with stator voltage saturation and unknown load.A smooth switching mechanis...This article investigates the anti-disturbance and stabilization problems for the nonlinear uncertain permanent magnet synchronous motor(PMSM)with stator voltage saturation and unknown load.A smooth switching mechanism is presented to structure the adaptive integral terminal sliding mode control(SMC)strategy.The control design consists of compensation control and nominal control,which improves the rapidity and accuracy of trajectory tracking.The smooth saturation model based on the error function is applied to approximate the voltage saturation phenomenon.Additionally,to deal with the adverse effects of various unknown disturbances,including model parameter uncertainties and unknown external load disturbances,an improved disturbance observer(DO)is proposed.This observer effectively suppresses the fluctuations caused by fixed gain during the starting period of the system.Finally,the experimental results under different conditions show that the proposed strategy has good tracking and disturbance suppression performances.展开更多
For new renewable clean energy,triboelectric nanogenerators(TENGs)have shown great potential in response to the world energy crisis.Nevertheless,the alternating-current signal generated by a TENG needs to be converted...For new renewable clean energy,triboelectric nanogenerators(TENGs)have shown great potential in response to the world energy crisis.Nevertheless,the alternating-current signal generated by a TENG needs to be converted into a direct-current signal to be effective in applications.Therefore,a power management circuit,comprising a clamp rectifier circuit and a mechanical switch,is proposed for the conversion and produces a signal having a low ripple coefficient.The power management circuit adopts a clamp circuit as the rectifier circuit to increase the rectified voltage,and reduces the loss resulted from the components by reducing the use of discrete components;the electronic switch in the buck regulator circuit is replaced with a mechanical switch to reduce cost and complexity.In a series of experiments,this power management circuit displayed a stable output voltage with a ripple voltage of 0.07 V,crest factor of 1.01,and ripple coefficient of 2.2%.The TENG provides a feasible method to generate stable electric energy and to supply power to low-consumption electronic devices.展开更多
Neuromorphic computing has the potential to overcome limitations of traditional silicon technology in machine learning tasks.Recent advancements in large crossbar arrays and silicon-based asynchronous spiking neural n...Neuromorphic computing has the potential to overcome limitations of traditional silicon technology in machine learning tasks.Recent advancements in large crossbar arrays and silicon-based asynchronous spiking neural networks have led to promising neuromorphic systems.However,developing compact parallel computing technology for integrating artificial neural networks into traditional hardware remains a challenge.Organic computational materials offer affordable,biocompatible neuromorphic devices with exceptional adjustability and energy-efficient switching.Here,the review investigates the advancements made in the development of organic neuromorphic devices.This review explores resistive switching mechanisms such as interface-regulated filament growth,molecular-electronic dynamics,nanowire-confined filament growth,and vacancy-assisted ion migration,while proposing methodologies to enhance state retention and conductance adjustment.The survey examines the challenges faced in implementing low-power neuromorphic computing,e.g.,reducing device size and improving switching time.The review analyses the potential of these materials in adjustable,flexible,and low-power consumption applications,viz.biohybrid spiking circuits interacting with biological systems,systems that respond to specific events,robotics,intelligent agents,neuromorphic computing,neuromorphic bioelectronics,neuroscience,and other applications,and prospects of this technology.展开更多
This paper deals with the problem of synchronization for a class of uncertain chaotic systems. The uncertainties under consideration are assumed to be Lipschitz-like nonlinearity in tracking error, with unknown growth...This paper deals with the problem of synchronization for a class of uncertain chaotic systems. The uncertainties under consideration are assumed to be Lipschitz-like nonlinearity in tracking error, with unknown growth rate. A logic-based switching mechanism is presented for tracking a smooth orbit that can be a limit cycle or a chaotic orbit of another system. Based on the Lyapunov approach, the adaptation law is determined to tune the controller gain vector online according to the possible nonlinearities. To demonstrate the efficiency of the proposed scheme, the well-known chaotic system namely Chua＇s circuit is considered as an illustrative example.展开更多
Polycrystalline LaCrO3（LCO） thin films are deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition and used as the switching material to construct resistive random access memory devices. The unipolar resist...Polycrystalline LaCrO3（LCO） thin films are deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition and used as the switching material to construct resistive random access memory devices. The unipolar resistive switching（RS） behavior in the Au/LCO/Pt devices exhibits a high resistance ratio of ~104 between the high resistance state（HRS） and low resistance state（LRS） and exhibits excellent endurance/retention characteristics.The conduction mechanism of the HRS in the high voltage range is dominated by the Schottky emission, while the Ohmic conduction dictates the LRS and the low voltage range of HRS. The RS behavior in the Au/LCO/Pt devices can be understood by the formation and rupture of conducting filaments consisting of oxygen vacancies,which is validated by the temperature dependence of resistance and x-ray photoelectron spectroscopy results.Further analysis shows that the reset current IR and reset power PR in the reset processes exhibit a scaling law with the resistance in LRS（R0）, which indicates that the Joule heating effect plays an essential role in the RS behavior of the Au/LCO/Pt devices.展开更多
With the progress of the semiconductor industry, resistive memories, especially the memristor, have drawn increasing attention. The resistive memory based on memrsitor has not been commercialized mainly because of dat...With the progress of the semiconductor industry, resistive memories, especially the memristor, have drawn increasing attention. The resistive memory based on memrsitor has not been commercialized mainly because of data error. Currently, there are more studies focused on fault tolerance of resistive memory. This paper studies the resistive switching mechanism which may have time-varying characteristics. Resistive switching mechanism is analyzed and its respective circuit model is established based on the memristor Spice model.展开更多
With the progress of the semiconductor industry,the resistive random-access memory（RAM） has drawn increasing attention.The discovery of the memristor has brought much attention to this study.Research has focused on ...With the progress of the semiconductor industry,the resistive random-access memory（RAM） has drawn increasing attention.The discovery of the memristor has brought much attention to this study.Research has focused on the resistive switching characteristics of different materials and the analysis of resistive switching mechanisms.We discuss the resistive switching mechanisms of different materials in this paper and analyze the differences of those mechanisms from the view point of circuitry to establish their respective circuit models.Finally,simulations are presented.We give the prospect of using different materials in resistive RAM on account of their resistive switching mechanisms,which are applied to explain their resistive switchings.展开更多
Memristive devices have attracted intensive attention in developing hardware neuromorphic computing systems with high energy efficiency due to their simple structure,low power consumption,and rich switching dynamics r...Memristive devices have attracted intensive attention in developing hardware neuromorphic computing systems with high energy efficiency due to their simple structure,low power consumption,and rich switching dynamics resembling biological synapses and neurons in the last decades.Fruitful demonstrations have been achieved in memristive synapses neurons and neural networks in the last few years.Versatile dynamics are involved in the data processing and storage in biological neurons and synapses,which ask for carefully tuning the switching dynamics of the memristive emulators.Note that switching dynamics of the memristive devices are closely related to switching mechanisms.Herein,from the perspective of switching dynamics modulations,the mainstream switching mechanisms including redox reaction with ion migration and electronic effect have been systemically reviewed.The approaches to tune the switching dynamics in the devices with different mechanisms have been described.Finally,some other mechanisms involved in neuromorphic computing are briefly introduced.展开更多
Resistive switching(RS)devices have great application prospects in the emerging memory field and neuromorphic field,but their stability and unclear RS mechanism limit their relevant applications.In this work,we constr...Resistive switching(RS)devices have great application prospects in the emerging memory field and neuromorphic field,but their stability and unclear RS mechanism limit their relevant applications.In this work,we construct a hydrogenated Au/SnO_(2)nanowire(NW)/Au device with two back-to-back Schottky diodes and investigate the RS characteristics in air and vacuum.We find that the Ion/Io ff ratio increases from 20 to 10^(4)when the read voltage decreases from 3.1 V to^(-1)V under the condition of electric field.Moreover,the rectification ratio can reach as high as 10^4owing to oxygen ion migration modulated by the electric field.The nanodevice also shows non-volatile resistive memory characteristic.The RS mechanism is clarified based on the changes of the Schottky barrier width and height at the interface of Au/SnO_(2)NW/Au device.Our results provide a strategy for designing high-performance memristive devices based on SnO_(2)NWs.展开更多
LepA, the highly conserved translational GTPase (trGTPase), triggers one-codon back-movement of the elongating ribosome. Here we identify a new enzymatic activity
In recent years, cyber attacks have posed great challenges to the development of cyber-physical systems. It is of great significance to study secure state estimation methods to ensure the safe and stable operation of ...In recent years, cyber attacks have posed great challenges to the development of cyber-physical systems. It is of great significance to study secure state estimation methods to ensure the safe and stable operation of the system. This paper proposes a secure state estimation for multi-input and multi-output continuous-time linear cyber-physical systems with sparse actuator and sensor attacks. First, for sparse sensor attacks, we propose an adaptive switching mechanism to mitigate the impact of sparse sensor attacks by filtering out their attack modes. Second, an unknown input sliding mode observer is designed to not only observe the system states, sensor attack signals, and measurement noise present in the system but also counteract the effects of sparse actuator attacks through an unknown input matrix. Finally, for the design of an unknown input sliding mode state observer, the feasibility of the observing system is demonstrated by means of Lyapunov functions. Additionally, simulation experiments are conducted to show the effectiveness of this method.展开更多
Sesame （Sesamue indicum L.） is one of the most important oilseed crops with high oil yield. Here, we described a simple and efficient method for constructing a normalized cDNA library from a high oil content cultiva...Sesame （Sesamue indicum L.） is one of the most important oilseed crops with high oil yield. Here, we described a simple and efficient method for constructing a normalized cDNA library from a high oil content cultivar of sesame Zhongzhi 14, during its oil accumulation stages. It combined switching mechanism at 5？end of RNA transcript （SMART） technique and duplex-specific nuclease （DSN） normalization methods. Double-stranded cDNAs were synthesized from mRNAs, processed by normalization and Sfi I restriction endonuclease, and finally the cDNAs were ligated to pDNR-LIB vector. The ligation mixture was transformed into Escherichia coli DH10B by electroporation. The capacity of the library was 1.0？06 clones in this library. Gel electrophoresis results indicated the fragments ranged from 700 to 2 000 bp, with the average size of 1 800 bp. Random picking clones showed that the recombination rate was 100%. The results showed that the cDNA library constructed successfully was a full-length library with high quality, and could be used to screen the genes related to development of oil synthesis.展开更多
The development of stimuli-responsive switching memory devices and the elucidation of their switching mechanisms in specific environments are crucial for advancing the field of molecular electronics.Herein,we propose ...The development of stimuli-responsive switching memory devices and the elucidation of their switching mechanisms in specific environments are crucial for advancing the field of molecular electronics.Herein,we propose two distinct two-dimensional covalent organic frameworks(COFs),namely Py-EDA and Py-BDA,incorporating acetylene(-C≡C-)or diacetylene(-C≡C-C≡C-)moieties,respectively,targeting fabricate memory devices exhibiting stimuli-responsive switching behavior.Our findings demonstrate that the incorporation of acetylene units effectively modulates the electronic band structure and enhances the degree ofπ-conjugation,resulting in devices that exhibit typical bipolar nonvolatile memory performance.Notably,upon thermal treatment,the memory behavior of the ITO/Py-BDA/Ag device transitions to a write-once-read-many-times(WORM)mode,displaying decreased SET voltage,increased ON/OFF current ratio,and remarkable retention reliability and cycle stability.This switching behavior is attributed to the occurrence of interlayer solid-state topological polymerization at 350℃,leading to the transformation of diacetylene columnar arrays into enyne chains within Py-BDA,thereby further promoting interlayer charge transfer and separation.展开更多
Artificial intelligence(AI)advancements are driving the need for highly paral-lel and energy-efficient computing analogous to the human brain and visualsystem.Inspired by the human brain,resistive random-access memori...Artificial intelligence(AI)advancements are driving the need for highly paral-lel and energy-efficient computing analogous to the human brain and visualsystem.Inspired by the human brain,resistive random-access memories(ReRAMs)have recently emerged as an essential component of the intelligentcircuitry architecture for developing high-performance neuromorphic comput-ing systems.This occurs due to their fast switching with ultralow power con-sumption,high ON/OFF ratio,excellent data retention,good endurance,andeven great possibilities for altering resistance analogous to their biologicalcounterparts for neuromorphic computing applications.Additionally,with theadvantages of photoelectric dual modulation of resistive switching,ReRAMsallow optically inspired artificial neural networks and reconfigurable logicoperations,promoting innovative in-memory computing technology forneuromorphic computing and image recognition tasks.Optoelectronicneuromorphic computing architectured ReRAMs can simulate neural func-tionalities,such as light-triggered long-term/short-term plasticity.They can beused in intelligent robotics and bionic neurological optoelectronic systems.Metal oxide(MOx)–polymer hybrid nanocomposites can be beneficial as anactive layer of the bistable metal–insulator–metal ReRAM devices,which holdpromise for developing high-performance memory technology.This reviewexplores the state of the art for developing memory storage,advancement inmaterials,and switching mechanisms for selecting the appropriate materials asactive layers of ReRAMs to boost the ON/OFF ratio,flexibility,and memorydensity while lowering programming voltage.Furthermore,material designcum-synthesis strategies that greatly influence the overall performance of MOx–polymer hybrid nanocomposite ReRAMs and their performances arehighlighted.Additionally,the recent progress of multifunctional optoelectronicMOx–polymer hybrid composites-based ReRAMs are explored as artificial syn-apses for neural networks to emulate neuromorphic visualization and memo-rize information.Finally,the challenges,limitations,and future outlooks ofthe fabrication of MOx–polymer hybrid composite ReRAMs over the conven-tional von Neumann computing systems are discussed.展开更多
Co_(3)O_(4)spinel oxides have manifested promising activity toward the oxygen evolution reaction(OER)through effective modifications.For them to become top electrocatalysts,however,accurate accounts of the catalytic k...Co_(3)O_(4)spinel oxides have manifested promising activity toward the oxygen evolution reaction(OER)through effective modifications.For them to become top electrocatalysts,however,accurate accounts of the catalytic kinetics are essential to gain a deep understanding of the activity promotion mechanisms.Herein,we use a newly proposed kinetic model based on energetic span as the rate-determining term for the electrocatalytic reaction to throw light on the promotion mechanism of Co_(3)O_(4)interfaced with nickel hydroxides(NiO_(x)H_(y))for the OER.We find that depending on the electrode potential,the OER kinetics at the designed interface between Co_(3)O_(4)and NiO_(x)H_(y)are boosted in entirely different ways.As a result,the OER can occur at a lower onset potential as well as a low Tafel slope.This work emphasizes the benefit of using rational theoretical models for electrocatalyst design.展开更多
The rapid development of big-data analytics(BDA),internet of things(IoT)and artificial intelligent Technology(AI)demand outstanding electronic devices and systems with faster processing speed,lower power consumption,a...The rapid development of big-data analytics(BDA),internet of things(IoT)and artificial intelligent Technology(AI)demand outstanding electronic devices and systems with faster processing speed,lower power consumption,and smarter computer architecture.Memristor,as a promising Non-Volatile Memory(NVM)device,can effectively mimic biological synapse,and has been widely studied in recent years.The appearance and development of two-dimensional materials(2D material)accelerate and boost the progress of memristor systems owing to a bunch of the particularity of 2D material compared to conventional transition metal oxides(TMOs),therefore,2D material-based memristors are called as new-generation intelligent memristors.In this review,the memristive(resistive switching)phenomena and the development of new-generation memristors are demonstrated involving graphene(GR),transition-metal dichalcogenides(TMDs)and hexagonal boron nitride(h-BN)based memristors.Moreover,the related progress of memristive mechanisms is remarked.展开更多
The conductive path formed by the interstitial Ag or substitutional Ag in Hf02 was investigated by using the Vienna ab initio simulation package based on the DFT theory. The calculated results indicated that the order...The conductive path formed by the interstitial Ag or substitutional Ag in Hf02 was investigated by using the Vienna ab initio simulation package based on the DFT theory. The calculated results indicated that the ordering of interstitial Ag ions at special positions can form a conductive path, and it cannot form at other positions.The orientation dependence of this conductive path was then investigated. Various types of super cells are also built to study the rupture of the path, which corresponds to some possible ＂off＂ states.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.61803203).
文摘The internal structure of the inertial measurement unit(IMU)in active state is easily damaged in the high overload environment.So that the IMU is usually required to be powered within the disappearance of the high overload.In this paper,a mechanical switch is designed to enable the IMU based on the analysis of the impact of high overload on the power-supply circuit.In which,parameters of mechanical switch are determined through theoretical calculation and data analysis.The innovation of the proposed structure lies in that the mechanical switch is triggered through the high overload process and could provide a delay signal for the circuit.After all,the proposed switch is tested through mechanical simulation,impact test and practical test.The experimental results show that the designed mechanical switch can effectively and reliably provide the delay for the circuit and guarantee operation of the IMU under high overload.
基金State Grid Corporation Headquarters Science and Technology Project,Grant/Award Number:5500-20220110A-1-1-ZN。
文摘Fast mechanical switches(FMSs)are critical components of DC circuit breakers(DCCBs),which require the switch action time to break to a sufficient distance within 3 ms in the DC line breaking scenario,while ensuring a long service life.The breaking mechanism significantly affects the current interruption capability of DCCBs.The operation of the repulsion mechanism,along with the morphology of the arc and its transformation within the interrupter chamber,collectively influence the breaking performance of the FMSs.This paper presents a comprehensive analysis of the FMSs,which serves as the pivotal component of controlled resonance combination circuit breakers(CRCBs).This study establishes a multi physics coupling simulation analysis method based on the equivalent circuit of repulsion mechanism discharge,combined with electromagnetic and solid mechanics fields.By constructing a full cycle magnetohydrodynamic particle arc(MHP)model and using a combined simulation of Finite Element joint model(FEJM),the evolution law of arc characteristics during the superimposed current interruption process was systematically explored.The focus was on analysing the physical process of the zero zone of the superimposed arc,the multi physics field coupling relationship of the arc,and the interaction mechanism with external characteristic parameters.Further combining with optimisation design methods,the effectiveness of the model was verified through experiments,FEJM provides comprehensive technical support for effectively reflecting the stress issues of core components during the breaking process of FMS and can provide accurate theoretical references for the optimisation design of mechanical motion components in FMS.It also accurately represents the arc extinguishing process during the breaking of FMS and provides a convenient method for the selection and design of circuit parameters for the entire circuit breaker.
基金supported by the National Natural Science Foundation under Grant 62273189the Shandong Province Natural Science Foundation under Grant ZR2021MF005Systems Science Plus Joint Research Program of Qingdao University under Grant XT2024201 of China supporting this research work.
文摘This article investigates the anti-disturbance and stabilization problems for the nonlinear uncertain permanent magnet synchronous motor(PMSM)with stator voltage saturation and unknown load.A smooth switching mechanism is presented to structure the adaptive integral terminal sliding mode control(SMC)strategy.The control design consists of compensation control and nominal control,which improves the rapidity and accuracy of trajectory tracking.The smooth saturation model based on the error function is applied to approximate the voltage saturation phenomenon.Additionally,to deal with the adverse effects of various unknown disturbances,including model parameter uncertainties and unknown external load disturbances,an improved disturbance observer(DO)is proposed.This observer effectively suppresses the fluctuations caused by fixed gain during the starting period of the system.Finally,the experimental results under different conditions show that the proposed strategy has good tracking and disturbance suppression performances.
基金the supports received from the Scientific Research Project of Education Department of Jilin Province(No.JJKH20210736KJ)the National Key R&D Project from the Minister of Science and Technology(Nos.2016YFA0202701 and 2016YFA0202704)the Beijing Municipal Science and Technology Commission(No.Z171100002017017).
文摘For new renewable clean energy,triboelectric nanogenerators(TENGs)have shown great potential in response to the world energy crisis.Nevertheless,the alternating-current signal generated by a TENG needs to be converted into a direct-current signal to be effective in applications.Therefore,a power management circuit,comprising a clamp rectifier circuit and a mechanical switch,is proposed for the conversion and produces a signal having a low ripple coefficient.The power management circuit adopts a clamp circuit as the rectifier circuit to increase the rectified voltage,and reduces the loss resulted from the components by reducing the use of discrete components;the electronic switch in the buck regulator circuit is replaced with a mechanical switch to reduce cost and complexity.In a series of experiments,this power management circuit displayed a stable output voltage with a ripple voltage of 0.07 V,crest factor of 1.01,and ripple coefficient of 2.2%.The TENG provides a feasible method to generate stable electric energy and to supply power to low-consumption electronic devices.
基金financially supported by the Ministry of Education(Singapore)(MOE-T2EP50220-0022)SUTD-MIT International Design Center(Singapore)+3 种基金SUTD-ZJU IDEA Grant Program(SUTD-ZJU(VP)201903)SUTD Kickstarter Initiative(SKI 2021_02_03,SKI 2021_02_17,SKI 2021_01_04)Agency of Science,Technology and Research(Singapore)(A20G9b0135)National Supercomputing Centre(Singapore)(15001618)。
文摘Neuromorphic computing has the potential to overcome limitations of traditional silicon technology in machine learning tasks.Recent advancements in large crossbar arrays and silicon-based asynchronous spiking neural networks have led to promising neuromorphic systems.However,developing compact parallel computing technology for integrating artificial neural networks into traditional hardware remains a challenge.Organic computational materials offer affordable,biocompatible neuromorphic devices with exceptional adjustability and energy-efficient switching.Here,the review investigates the advancements made in the development of organic neuromorphic devices.This review explores resistive switching mechanisms such as interface-regulated filament growth,molecular-electronic dynamics,nanowire-confined filament growth,and vacancy-assisted ion migration,while proposing methodologies to enhance state retention and conductance adjustment.The survey examines the challenges faced in implementing low-power neuromorphic computing,e.g.,reducing device size and improving switching time.The review analyses the potential of these materials in adjustable,flexible,and low-power consumption applications,viz.biohybrid spiking circuits interacting with biological systems,systems that respond to specific events,robotics,intelligent agents,neuromorphic computing,neuromorphic bioelectronics,neuroscience,and other applications,and prospects of this technology.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60974004)
文摘This paper deals with the problem of synchronization for a class of uncertain chaotic systems. The uncertainties under consideration are assumed to be Lipschitz-like nonlinearity in tracking error, with unknown growth rate. A logic-based switching mechanism is presented for tracking a smooth orbit that can be a limit cycle or a chaotic orbit of another system. Based on the Lyapunov approach, the adaptation law is determined to tune the controller gain vector online according to the possible nonlinearities. To demonstrate the efficiency of the proposed scheme, the well-known chaotic system namely Chua＇s circuit is considered as an illustrative example.
基金Supported by the Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences’Large-Scale Scientific Facility under Grant No U1532149the National Basic Research Program of China under Grant No2014CB931704
文摘Polycrystalline LaCrO3（LCO） thin films are deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition and used as the switching material to construct resistive random access memory devices. The unipolar resistive switching（RS） behavior in the Au/LCO/Pt devices exhibits a high resistance ratio of ~104 between the high resistance state（HRS） and low resistance state（LRS） and exhibits excellent endurance/retention characteristics.The conduction mechanism of the HRS in the high voltage range is dominated by the Schottky emission, while the Ohmic conduction dictates the LRS and the low voltage range of HRS. The RS behavior in the Au/LCO/Pt devices can be understood by the formation and rupture of conducting filaments consisting of oxygen vacancies,which is validated by the temperature dependence of resistance and x-ray photoelectron spectroscopy results.Further analysis shows that the reset current IR and reset power PR in the reset processes exhibit a scaling law with the resistance in LRS（R0）, which indicates that the Joule heating effect plays an essential role in the RS behavior of the Au/LCO/Pt devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.60921062)
文摘With the progress of the semiconductor industry, resistive memories, especially the memristor, have drawn increasing attention. The resistive memory based on memrsitor has not been commercialized mainly because of data error. Currently, there are more studies focused on fault tolerance of resistive memory. This paper studies the resistive switching mechanism which may have time-varying characteristics. Resistive switching mechanism is analyzed and its respective circuit model is established based on the memristor Spice model.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60921062)
文摘With the progress of the semiconductor industry,the resistive random-access memory（RAM） has drawn increasing attention.The discovery of the memristor has brought much attention to this study.Research has focused on the resistive switching characteristics of different materials and the analysis of resistive switching mechanisms.We discuss the resistive switching mechanisms of different materials in this paper and analyze the differences of those mechanisms from the view point of circuitry to establish their respective circuit models.Finally,simulations are presented.We give the prospect of using different materials in resistive RAM on account of their resistive switching mechanisms,which are applied to explain their resistive switchings.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1832116 and 51772112)Fundamental Research Funds for the Central Universities,China(Grant No.HUST:2016YXZD058).
文摘Memristive devices have attracted intensive attention in developing hardware neuromorphic computing systems with high energy efficiency due to their simple structure,low power consumption,and rich switching dynamics resembling biological synapses and neurons in the last decades.Fruitful demonstrations have been achieved in memristive synapses neurons and neural networks in the last few years.Versatile dynamics are involved in the data processing and storage in biological neurons and synapses,which ask for carefully tuning the switching dynamics of the memristive emulators.Note that switching dynamics of the memristive devices are closely related to switching mechanisms.Herein,from the perspective of switching dynamics modulations,the mainstream switching mechanisms including redox reaction with ion migration and electronic effect have been systemically reviewed.The approaches to tune the switching dynamics in the devices with different mechanisms have been described.Finally,some other mechanisms involved in neuromorphic computing are briefly introduced.
基金Chenzhou Science and Technology Plan Project of China(Grant No.ZDYF2020159)Scientific Research Project of Hunan Provincial Department of Education(Grant No.21C0708)。
文摘Resistive switching(RS)devices have great application prospects in the emerging memory field and neuromorphic field,but their stability and unclear RS mechanism limit their relevant applications.In this work,we construct a hydrogenated Au/SnO_(2)nanowire(NW)/Au device with two back-to-back Schottky diodes and investigate the RS characteristics in air and vacuum.We find that the Ion/Io ff ratio increases from 20 to 10^(4)when the read voltage decreases from 3.1 V to^(-1)V under the condition of electric field.Moreover,the rectification ratio can reach as high as 10^4owing to oxygen ion migration modulated by the electric field.The nanodevice also shows non-volatile resistive memory characteristic.The RS mechanism is clarified based on the changes of the Schottky barrier width and height at the interface of Au/SnO_(2)NW/Au device.Our results provide a strategy for designing high-performance memristive devices based on SnO_(2)NWs.
文摘LepA, the highly conserved translational GTPase (trGTPase), triggers one-codon back-movement of the elongating ribosome. Here we identify a new enzymatic activity
基金supported by the National Science Foundation of China(Nos.62271293,61903238)the Natural Science Foundation of Shandong Province,China(No.ZR2021MF035)the Social Science Planning Project of Shandong Province,China(No.22CYYJ13).
文摘In recent years, cyber attacks have posed great challenges to the development of cyber-physical systems. It is of great significance to study secure state estimation methods to ensure the safe and stable operation of the system. This paper proposes a secure state estimation for multi-input and multi-output continuous-time linear cyber-physical systems with sparse actuator and sensor attacks. First, for sparse sensor attacks, we propose an adaptive switching mechanism to mitigate the impact of sparse sensor attacks by filtering out their attack modes. Second, an unknown input sliding mode observer is designed to not only observe the system states, sensor attack signals, and measurement noise present in the system but also counteract the effects of sparse actuator attacks through an unknown input matrix. Finally, for the design of an unknown input sliding mode state observer, the feasibility of the observing system is demonstrated by means of Lyapunov functions. Additionally, simulation experiments are conducted to show the effectiveness of this method.
基金supported by the National Basic Research Program of China (2011cb109305)the Genetically Modified Organisms Breeding Major Projects, China (2009zx08004-002B)+1 种基金the Open Project Program of Key Laboratory for Oil Crops Biology, the Ministry of Agriculture, China (200703)the Foundation of Oil Crops Research Institute, Chinese Academy of Agricultural Sciences
文摘Sesame （Sesamue indicum L.） is one of the most important oilseed crops with high oil yield. Here, we described a simple and efficient method for constructing a normalized cDNA library from a high oil content cultivar of sesame Zhongzhi 14, during its oil accumulation stages. It combined switching mechanism at 5？end of RNA transcript （SMART） technique and duplex-specific nuclease （DSN） normalization methods. Double-stranded cDNAs were synthesized from mRNAs, processed by normalization and Sfi I restriction endonuclease, and finally the cDNAs were ligated to pDNR-LIB vector. The ligation mixture was transformed into Escherichia coli DH10B by electroporation. The capacity of the library was 1.0？06 clones in this library. Gel electrophoresis results indicated the fragments ranged from 700 to 2 000 bp, with the average size of 1 800 bp. Random picking clones showed that the recombination rate was 100%. The results showed that the cDNA library constructed successfully was a full-length library with high quality, and could be used to screen the genes related to development of oil synthesis.
基金supported by the National Natural Science Foundation of China(21972021)the Natural Science Foundation of Fujian Province(2024J01238)the 111 Project(D16008)。
文摘The development of stimuli-responsive switching memory devices and the elucidation of their switching mechanisms in specific environments are crucial for advancing the field of molecular electronics.Herein,we propose two distinct two-dimensional covalent organic frameworks(COFs),namely Py-EDA and Py-BDA,incorporating acetylene(-C≡C-)or diacetylene(-C≡C-C≡C-)moieties,respectively,targeting fabricate memory devices exhibiting stimuli-responsive switching behavior.Our findings demonstrate that the incorporation of acetylene units effectively modulates the electronic band structure and enhances the degree ofπ-conjugation,resulting in devices that exhibit typical bipolar nonvolatile memory performance.Notably,upon thermal treatment,the memory behavior of the ITO/Py-BDA/Ag device transitions to a write-once-read-many-times(WORM)mode,displaying decreased SET voltage,increased ON/OFF current ratio,and remarkable retention reliability and cycle stability.This switching behavior is attributed to the occurrence of interlayer solid-state topological polymerization at 350℃,leading to the transformation of diacetylene columnar arrays into enyne chains within Py-BDA,thereby further promoting interlayer charge transfer and separation.
基金Council of Scientific and Industrial Research,India,Grant/Award Number:08/096(0012)/2020-EMR-IGovernment of Uttar Pradesh,India,Grant/Award Numbers:108/2021/2585/Sattar-4-2021-4(28)/2021/20,78/2022/1984/Sattar-4-2022-003-70-4099/7/022/19,CST/D-1524+1 种基金Chaudhary Charan Singh University,India,Grant/Award Number:Dev./1043/29.06.2022National Research Foundation of Korea,Grant/Award Numbers:2019R1A2C1085448,2023R1A2C1005421。
文摘Artificial intelligence(AI)advancements are driving the need for highly paral-lel and energy-efficient computing analogous to the human brain and visualsystem.Inspired by the human brain,resistive random-access memories(ReRAMs)have recently emerged as an essential component of the intelligentcircuitry architecture for developing high-performance neuromorphic comput-ing systems.This occurs due to their fast switching with ultralow power con-sumption,high ON/OFF ratio,excellent data retention,good endurance,andeven great possibilities for altering resistance analogous to their biologicalcounterparts for neuromorphic computing applications.Additionally,with theadvantages of photoelectric dual modulation of resistive switching,ReRAMsallow optically inspired artificial neural networks and reconfigurable logicoperations,promoting innovative in-memory computing technology forneuromorphic computing and image recognition tasks.Optoelectronicneuromorphic computing architectured ReRAMs can simulate neural func-tionalities,such as light-triggered long-term/short-term plasticity.They can beused in intelligent robotics and bionic neurological optoelectronic systems.Metal oxide(MOx)–polymer hybrid nanocomposites can be beneficial as anactive layer of the bistable metal–insulator–metal ReRAM devices,which holdpromise for developing high-performance memory technology.This reviewexplores the state of the art for developing memory storage,advancement inmaterials,and switching mechanisms for selecting the appropriate materials asactive layers of ReRAMs to boost the ON/OFF ratio,flexibility,and memorydensity while lowering programming voltage.Furthermore,material designcum-synthesis strategies that greatly influence the overall performance of MOx–polymer hybrid nanocomposite ReRAMs and their performances arehighlighted.Additionally,the recent progress of multifunctional optoelectronicMOx–polymer hybrid composites-based ReRAMs are explored as artificial syn-apses for neural networks to emulate neuromorphic visualization and memo-rize information.Finally,the challenges,limitations,and future outlooks ofthe fabrication of MOx–polymer hybrid composite ReRAMs over the conven-tional von Neumann computing systems are discussed.
基金This work was supported by the Natural Science Foundation of China(Grant 21832004)Fundamental Research Funds for the Central Universities(2042021kf1047)+1 种基金China Postdoctoral Science Foundation Funded Project(2021M692470)China National Postdoctoral Program for Innovative Talents(Grant BX20200253).The theoretical calculations have been done on the supercomputing system in the Supercomputing Center of Wuhan University.
文摘Co_(3)O_(4)spinel oxides have manifested promising activity toward the oxygen evolution reaction(OER)through effective modifications.For them to become top electrocatalysts,however,accurate accounts of the catalytic kinetics are essential to gain a deep understanding of the activity promotion mechanisms.Herein,we use a newly proposed kinetic model based on energetic span as the rate-determining term for the electrocatalytic reaction to throw light on the promotion mechanism of Co_(3)O_(4)interfaced with nickel hydroxides(NiO_(x)H_(y))for the OER.We find that depending on the electrode potential,the OER kinetics at the designed interface between Co_(3)O_(4)and NiO_(x)H_(y)are boosted in entirely different ways.As a result,the OER can occur at a lower onset potential as well as a low Tafel slope.This work emphasizes the benefit of using rational theoretical models for electrocatalyst design.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.51971070 and 10974037)National Key Research Program of China(No.2016YFA0200403)+2 种基金Eu-FP7 Project(No.247644),CAS Strategy Pilot Program(No.XDA 09020300)C.Wang acknowledges the support of the Fundamental Research Funds for the Central Universities(buctrc 202122)Y.Xie acknowledges the support of Beihang Youth Talent Funding Plan(No.YWF-18-BJ-Y-196).
文摘The rapid development of big-data analytics(BDA),internet of things(IoT)and artificial intelligent Technology(AI)demand outstanding electronic devices and systems with faster processing speed,lower power consumption,and smarter computer architecture.Memristor,as a promising Non-Volatile Memory(NVM)device,can effectively mimic biological synapse,and has been widely studied in recent years.The appearance and development of two-dimensional materials(2D material)accelerate and boost the progress of memristor systems owing to a bunch of the particularity of 2D material compared to conventional transition metal oxides(TMOs),therefore,2D material-based memristors are called as new-generation intelligent memristors.In this review,the memristive(resistive switching)phenomena and the development of new-generation memristors are demonstrated involving graphene(GR),transition-metal dichalcogenides(TMDs)and hexagonal boron nitride(h-BN)based memristors.Moreover,the related progress of memristive mechanisms is remarked.
基金supported by the National Youth Science Foundation,China(No.61006064)
文摘The conductive path formed by the interstitial Ag or substitutional Ag in Hf02 was investigated by using the Vienna ab initio simulation package based on the DFT theory. The calculated results indicated that the ordering of interstitial Ag ions at special positions can form a conductive path, and it cannot form at other positions.The orientation dependence of this conductive path was then investigated. Various types of super cells are also built to study the rupture of the path, which corresponds to some possible ＂off＂ states.
