In this paper,a non-negative adaptive mechanism based on an adaptive nonsingular fast terminal sliding mode control strategy is proposed to have finite time and high-speed trajectory tracking for parallel manipulators...In this paper,a non-negative adaptive mechanism based on an adaptive nonsingular fast terminal sliding mode control strategy is proposed to have finite time and high-speed trajectory tracking for parallel manipulators with the existence of unknown bounded complex uncertainties and external disturbances.The proposed approach is a hybrid scheme of the online non-negative adaptive mechanism,tracking differentiator,and nonsingular fast terminal sliding mode control(NFTSMC).Based on the online non-negative adaptive mechanism,the proposed control can remove the assumption that the uncertainties and disturbances must be bounded for the NFTSMC controllers.The proposed controller has several advantages such as simple structure,easy implementation,rapid response,chattering-free,high precision,robustness,singularity avoidance,and finite-time convergence.Since all control parameters are online updated via tracking differentiator and non-negative adaptive law,the tracking control performance at high-speed motions can be better in real-time requirement and disturbance rejection ability.Finally,simulation results validate the effectiveness of the proposed method.展开更多
The rapid growth of Internet of things devices and the emergence of rapidly evolving network threats have made traditional security assessment methods inadequate.Federated learning offers a promising solution to exped...The rapid growth of Internet of things devices and the emergence of rapidly evolving network threats have made traditional security assessment methods inadequate.Federated learning offers a promising solution to expedite the training of security assessment models.However,ensuring the trustworthiness and robustness of federated learning under multi-party collaboration scenarios remains a challenge.To address these issues,this study proposes a shard aggregation network structure and a malicious node detection mechanism,along with improvements to the federated learning training process.First,we extract the data features of the participants by using spectral clustering methods combined with a Gaussian kernel function.Then,we introduce a multi-objective decision-making approach that combines data distribution consistency,consensus communication overhead,and consensus result reliability in order to determine the final network sharing scheme.Finally,by integrating the federated learning aggregation process with the malicious node detection mechanism,we improve the traditional decentralized learning process.Our proposed ShardFed algorithm outperforms conventional classification algorithms and state-of-the-art machine learning methods like FedProx and FedCurv in convergence speed,robustness against data interference,and adaptability across multiple scenarios.Experimental results demonstrate that the proposed approach improves model accuracy by up to 2.33%under non-independent and identically distributed data conditions,maintains higher performance with malicious nodes containing poisoned data ratios of 20%–50%,and significantly enhances model resistance to low-quality data.展开更多
This paper explores the issue of secure synchronization control in piecewise-homogeneous Markovian jump delay neural networks affected by denial-of-service(DoS)attacks.Initially,a novel memory-based adaptive event-tri...This paper explores the issue of secure synchronization control in piecewise-homogeneous Markovian jump delay neural networks affected by denial-of-service(DoS)attacks.Initially,a novel memory-based adaptive event-triggered mechanism(MBAETM)is designed based on sequential growth rates,focusing on event-triggered conditions and thresholds.Subsequently,from the perspective of defenders,non-periodic DoS attacks are re-characterized,and a model of irregular DoS attacks with cyclic fluctuations within time series is further introduced to enhance the system's defense capabilities more effectively.Additionally,considering the unified demands of network security and communication efficiency,a resilient memory-based adaptive event-triggered mechanism(RMBAETM)is proposed.A unified Lyapunov-Krasovskii functional is then constructed,incorporating a loop functional to thoroughly consider information at trigger moments.The master-slave system achieves synchronization through the application of linear matrix inequality techniques.Finally,the proposed methods'effectiveness and superiority are confirmed through four numerical simulation examples.展开更多
Long-term niche differentiation will lead to the evolution of diverse adaptive strategies for species in diverse environments. The present study selected two Forsythia species, Forsythia mandshurica(Fm)-which naturall...Long-term niche differentiation will lead to the evolution of diverse adaptive strategies for species in diverse environments. The present study selected two Forsythia species, Forsythia mandshurica(Fm)-which naturally occurs in a cold temperate zone and Forsythia suspensa(Fs)-which thrives in a warm temperate zone-to reveal their differential chilling defense mechanisms by integrating morpho-physiological,transcriptomic, and metabolomic data. Transcriptome results show that Fm has evolved in a series of adaptive mechanisms designed to help the plants to cope with chilling stress by enhancing sugar, amino acid, hormone, polyamine, and phenol content to improve cell osmotic potential and to mitigate petal browning. Metabolomic data suggested the increased chilling resistance of Fm relies on in the plant being rich in a-linolenic acid, linoleic acid, as well as two amino acids, Phe and Trp, and has low levels of cinnamic acid and gramine in flowers compared to Fs. A higher abundance of glutathione disulfide and NADPH regulated by glutathione peroxidases and NADPH improved the ability of the cellular antioxidant and reduction-oxidation system stability in Fm;Additionally, the elevated levels of pyruvate, a-ketoglutaric acid, and oxaloacetic acid in Fm contributed to a significantly enhanced ATP production in mitochondria. Through Ka/Ks and gene expression analysis,four transcription factors, EVM0025036(bHLH), EVM0010639 and EVM0007275(AP2), and EVM0025908(bZIP) were identified that may contribute to the high cold tolerance of Fm. These adaptations highlight the intricate interplay between genetic and physiological processes that shape the survival strategies of plants in response to their specific ecological niches.展开更多
This paper addresses the consensus problem of nonlinear multi-agent systems subject to external disturbances and uncertainties under denial-ofservice(DoS)attacks.Firstly,an observer-based state feedback control method...This paper addresses the consensus problem of nonlinear multi-agent systems subject to external disturbances and uncertainties under denial-ofservice(DoS)attacks.Firstly,an observer-based state feedback control method is employed to achieve secure control by estimating the system's state in real time.Secondly,by combining a memory-based adaptive eventtriggered mechanism with neural networks,the paper aims to approximate the nonlinear terms in the networked system and efficiently conserve system resources.Finally,based on a two-degree-of-freedom model of a vehicle affected by crosswinds,this paper constructs a multi-unmanned ground vehicle(Multi-UGV)system to validate the effectiveness of the proposed method.Simulation results show that the proposed control strategy can effectively handle external disturbances such as crosswinds in practical applications,ensuring the stability and reliable operation of the Multi-UGV system.展开更多
For survival,bats of the suborder Microchiropetra emit intense ultrasonic pulses and analyze the weak returning echoes to extract the direction,distance,velocity,size,and shape of the prey.Although these bats and othe...For survival,bats of the suborder Microchiropetra emit intense ultrasonic pulses and analyze the weak returning echoes to extract the direction,distance,velocity,size,and shape of the prey.Although these bats and other mammals share the common layout of the auditory pathway and sound coding mechanism,they have highly developed auditory systems to process biologically relevant pulses at the expense of a reduced visual system.During this active biosonar behavior,they progressively shorten the pulse duration,decrease the amplitude and pulse-echo gap as they search,approach and finally intercept the prey.Presumably,these changes in multiple pulse parameters throughout the entire course of hunting enable them to extract maximal information about localized prey from the returning echoes.To hunt successfully,the auditory system of these bats must be less sensitive to intense emitted pulses but highly sensitive to weak returning echoes.They also need to recognize and differentiate the echoes of their emitted pulses from echoes of pulses emitted by other conspecifics.Past studies have shown the following mechanical and neural adaptive mechanisms underlying the successful bat biosonar behavior:(1)Forward orienting and highly mobile pinnae for effective scanning,signal reception,sound pressure transformation and mobile auditory sensitivity;(2)Avoiding and detecting moving targets more successfully than stationary ones;(3)Coordinated activity of highly developed laryngeal and middle ear muscles during pulse emission and reception;(4)Mechanical and neural attenuation of intense emitted pulses to prepare for better reception of weak returning echoes;(5)Increasing pulse repetition rate to improve multiple-parametric selectivity to echoes;(6)Dynamic variation of duration selectivity and recovery cycle of auditory neurons with hunting phase for better echo analysis;(7)Maximal multiple-parametric selectivity to expected echoes returning within a time window after pulse emission;(8)Pulse-echo delaysensitive neurons in higher auditory centers for echo ranging;(9)Corticofugal modulation to improve on-going multiple-parametric signal processing and reorganize signal representation,and(10)A large area of the superior colliculus,pontine nuclei and cerebellum that is sensitive to sound for sensori-motor integration.All these adaptive mechanisms facilitate the bat to effectively extract prey features for successful hunting.展开更多
In this work,an adaptive sampling control strategy for distributed predictive control is proposed.According to the proposed method,the sampling rate of each subsystem of the accused object is determined based on the p...In this work,an adaptive sampling control strategy for distributed predictive control is proposed.According to the proposed method,the sampling rate of each subsystem of the accused object is determined based on the periodic detection of its dynamic behavior and calculations made using a correlation function.Then,the optimal sampling interval within the period is obtained and sent to the corresponding sub-prediction controller,and the sampling interval of the controller is changed accordingly before the next sampling period begins.In the next control period,the adaptive sampling mechanism recalculates the sampling rate of each subsystem’s measurable output variable according to both the abovementioned method and the change in the dynamic behavior of the entire system,and this process is repeated.Such an adaptive sampling interval selection based on an autocorrelation function that measures dynamic behavior can dynamically optimize the selection of sampling rate according to the real-time change in the dynamic behavior of the controlled object.It can also accurately capture dynamic changes,meaning that each sub-prediction controller can more accurately calculate the optimal control quantity at the next moment,significantly improving the performance of distributed model predictive control(DMPC).A comparison demonstrates that the proposed adaptive sampling DMPC algorithm has better tracking performance than the traditional DMPC algorithm.展开更多
According to the basic functions and objectives of Cognitive Radio (CR) systems, the cognition-based adaptive control mechanism is the generalization of the research contents and approaches of cognitive radio systems....According to the basic functions and objectives of Cognitive Radio (CR) systems, the cognition-based adaptive control mechanism is the generalization of the research contents and approaches of cognitive radio systems. Therefore, the mechanism is described by a cognition loop, which contains the following parts: environment, inner structure of intelligent systems, observation and action.展开更多
The phenomenon of fear memory generalization can be defined as the expansion of an individual's originally specific fear responses to a similar yet genuinely harmless stimulus or situation subsequent to the occurr...The phenomenon of fear memory generalization can be defined as the expansion of an individual's originally specific fear responses to a similar yet genuinely harmless stimulus or situation subsequent to the occurrence of a traumatic event[1].Fear generalization within the normal range represents an adaptive evolutionary mechanism to facilitate prompt reactions to potential threats and to enhance the likelihood of survival.展开更多
Marine current energy has been increasingly used because of its predictable higher power potential.Owing to the external disturbances of various flow velocity and the high nonlinear effects on the marine current turbi...Marine current energy has been increasingly used because of its predictable higher power potential.Owing to the external disturbances of various flow velocity and the high nonlinear effects on the marine current turbine(MCT)system,the nonlinear controllers which rely on precise mathematical models show poor performance under a high level of parameters’uncertainties.This paper proposes an adaptive single neural control(ASNC)strategy for variable step-size perturb and observe(P&O)maximum power point tracking(MPPT)control.Firstly,to automatically update the neuron weights of SNC for the nonlinear systems,an adaptive mechanism is proposed to adaptively adjust the weighting and learning coefficients.Secondly,aiming to generate the exact reference speed for ASNC to extract the maximum power,a variable step-size law based on speed increment is designed to strike a balance between tracking speed and accuracy of P&O MPPT.The robust stability of the MCT control system is guaranteed by the Lyapunov theorem.Comparative simulation results show that this strategy has favorable adaptive performance under variable velocity conditions,and the MCT system operates at maximum power point steadily.展开更多
Saussurea medusa,Saussurea hypsipeta and Saussurea obvallata are typical alpine snowline plants growing in the Qinghai-Tibet plateau.They are characterized by a specialized morphology.S.medusa and S.hypsipeta have ver...Saussurea medusa,Saussurea hypsipeta and Saussurea obvallata are typical alpine snowline plants growing in the Qinghai-Tibet plateau.They are characterized by a specialized morphology.S.medusa and S.hypsipeta have very dense trichomes on whole plant,whereas S.obvallata has transparent bracts covered inflorescences.The different forms reflect their adaptation to cold environments.To investigate the different mechanisms of adaptation of these species to cold temperatures,transcriptome sequencing was performed in three species of Saussurea DC.A total of 116394137237 and 113879 Unigenes were identified from S.medusa,S.hypsipeta and S.obvallata,respectively.Of these,55909(48.03%),65519(47.74%)and 51889(45.56%)Unigenes were matched in public databases.GO analysis identified that most of annotated Unigenes in the three species of plants were related to cellular,metabolic,and single−organism processes,and binding and catalytic activities.The differential expression of 37 genes related to environmental adaptation were discovered by pairwise comparisons.Of these,two candidate genes(Interaptin-like and CSLB3)related to trichome development were identified only in S.medusa and S.hypsipeta,which was consistent with their distinct morphology.Our data can provide a valuable resource for the further studies on the adaptive mechanisms of molecular and functional ecology in Saussurea DC.展开更多
Erigeron annuus(L.)Pers.,an alien species,is widely distributed in most areas of China.It was included in the third batch of invasive alien species list by the Ministry of Ecology and Environment of China,and it is a ...Erigeron annuus(L.)Pers.,an alien species,is widely distributed in most areas of China.It was included in the third batch of invasive alien species list by the Ministry of Ecology and Environment of China,and it is a first-level malignant invasive plant.Due to its great reproducibility with a mass of seeds,power adaptability to the external environment and strong allelopathy,it has highly invasive and adaptability,and has affected the development of the agriculture and forestry,the diversity of local species and the ecosystem.In this paper,we summarized the current invasion situation,invasion and adaptation mechanism of E.annuus,and prospected further research on E.annuus invasion mechanism,hoping to provide a reference for realizing its effective management.展开更多
The Polar Regions host one of the harshest and most unique ecosystems on Earth,harboring a diverse array of micro-and macro-organisms.These inhabitants showcase remarkable taxonomic and genetic originality,presenting ...The Polar Regions host one of the harshest and most unique ecosystems on Earth,harboring a diverse array of micro-and macro-organisms.These inhabitants showcase remarkable taxonomic and genetic originality,presenting unparalleled opportunities for bioprospecting,alongside demonstrating extraordinary adaptation mechanisms for survival.Furthermore,polar organisms play crucial roles in facilitating organic matter decomposition,carbon fixation and sequestration,and biogeochemical cycling.Moreover,these organisms serve as pivotal indicators of global climate shifts.Therefore,exploring the polar organisms and ecosystem holds profound and significant implications for gaining deeper insights into scientific frontiers such as global biodiversity,elementary cycling,climate change,resource utilization,and the awe of life in extreme environments.展开更多
This paper investigates the event-triggered security consensus problem for nonlinear multi-agent systems(MASs)under denial-of-service(Do S)attacks over an undirected graph.A novel adaptive memory observer-based anti-d...This paper investigates the event-triggered security consensus problem for nonlinear multi-agent systems(MASs)under denial-of-service(Do S)attacks over an undirected graph.A novel adaptive memory observer-based anti-disturbance control scheme is presented to improve the observer accuracy by adding a buffer for the system output measurements.Meanwhile,this control scheme can also provide more reasonable control signals when Do S attacks occur.To save network resources,an adaptive memory event-triggered mechanism(AMETM)is also proposed and Zeno behavior is excluded.It is worth mentioning that the AMETM's updates do not require global information.Then,the observer and controller gains are obtained by using the linear matrix inequality(LMI)technique.Finally,simulation examples show the effectiveness of the proposed control scheme.展开更多
In this paper, an approach to the control of continuous-time chaotic systems is proposed using the Takagi-Sugeno （TS） fuzzy model and adaptive adjustment. Sufficient conditions are derived to guarantee chaos control...In this paper, an approach to the control of continuous-time chaotic systems is proposed using the Takagi-Sugeno （TS） fuzzy model and adaptive adjustment. Sufficient conditions are derived to guarantee chaos control from Lyapunov stability theory. The proposed approach offers a systematic design procedure for stabilizing a large class of chaotic systems in the literature about chaos research. The simulation results on Rossler＇s system verify the effectiveness of the proposed methods.展开更多
Molecular mechanisms of plant responses to salinity stress and the physiological consequences of altered gene expression are reviewed. Extensive use of comparisons with halophytic plants and glycophytos provide a para...Molecular mechanisms of plant responses to salinity stress and the physiological consequences of altered gene expression are reviewed. Extensive use of comparisons with halophytic plants and glycophytos provide a paradigm for many responses to salinity exhibited by stress sensitive plants. Osmolyte biosynthesis, water flux control, and membrane transport of ions are important for maintenance and re-establishment of homeostasis. Transgenic plant and mutant analyses in Arabidopsis improve the understanding of stress responses and elements of stress signal transduction pathways. The genomic DNA sequences and cell-specific transcript expression data, combined with determinant identification based on molecular genetics, will provide the infrastructure for functional physiological dissection of salt tolerance determinants in plants. Protein interaction analysis, genetic activation and suppression screens will lead inevitably to an understanding of the interrelationships of the multiple signaling systems that control stress-adaptive responses and provide more opportunity to engineer salt tolerance in plants.展开更多
For the randomness of crane working load leading to the decrease of load spectrum prediction accuracy with time,an adaptive TSSA-HKRVM model for crane load spectrum regression prediction is proposed.The heterogeneous ...For the randomness of crane working load leading to the decrease of load spectrum prediction accuracy with time,an adaptive TSSA-HKRVM model for crane load spectrum regression prediction is proposed.The heterogeneous kernel relevance vector machine model(HKRVM)with comprehensive expression ability is established using the complementary advantages of various kernel functions.The combination strategy consisting of refraction reverse learning,golden sine,and Cauchy mutation+logistic chaotic perturbation is introduced to form a multi-strategy improved sparrow algorithm(TSSA),thus optimizing the relevant parameters of HKRVM.The adaptive updatingmechanismof the heterogeneous kernel RVMmodel under themulti-strategy improved sparrow algorithm(TSSA-HKMRVM)is defined by the sliding window design theory.Based on the sample data of the measured load spectrum,the trained adaptive TSSA-HKRVMmodel is employed to complete the prediction of the crane equivalent load spectrum.Applying this method toQD20/10 t×43m×12mgeneral bridge crane,the results show that:compared with other prediction models,although the complexity of the adaptive TSSA-HKRVMmodel is relatively high,the prediction accuracy of the load spectrum under long periods has been effectively improved,and the completeness of the load information during thewhole life cycle is relatively higher,with better applicability.展开更多
Cyber-physical systems(CPSs)take on the characteristics of both multiple rates of information collection and processing and the dependency on information exchanges.The purpose of this paper is to develop a joint recur...Cyber-physical systems(CPSs)take on the characteristics of both multiple rates of information collection and processing and the dependency on information exchanges.The purpose of this paper is to develop a joint recursive filtering scheme that estimates both unknown inputs and system states for multi-rate CPSs with unknown inputs.In cyberspace,the information transmission between the local joint filter and the sensors is governed by an adaptive event-triggered strategy.Furthermore,the desired parameters of joint filters are determined by a set of algebraic matrix equations in a recursive way,and a sufficient condition verifying the boundedness of filtering error covariance is found by resorting to some algebraic operation.A state fusion estimation scheme that uses local state estimation is proposed based on the covariance intersection(CI)based fusion conception.Lastly,an illustrative example demonstrates the effectiveness of the proposed adaptive event-triggered recursive filtering algorithm.展开更多
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
The massive use of polyhexamethylene guanidine(PHMG),as a typical bactericidal agent,raised environmental concerns to the public.This work comprehensively revealed the hormesis effects of PHMG occurred in waste activa...The massive use of polyhexamethylene guanidine(PHMG),as a typical bactericidal agent,raised environmental concerns to the public.This work comprehensively revealed the hormesis effects of PHMG occurred in waste activated sludge(WAS)on the generation of volatile fatty acids(VFAs)during anaerobic fermentation.The low level of PHMG(100 mg/g TSS)significantly promoted the VFAs generation(1283 mg COD/L,compared with 337 mg COD/L in the control)via synchronously facilitating the solubilization,hydrolysis,and acidification steps but inhibiting methanogenesis.Metagenomic analysis showed that the functional anaerobe(i.e.,Bacteroides,Macellibacteroide and Parabacteroide)and corresponding genetic expressions responsible for extracellular hydrolysis(i.e.,clp P),membrane transport(i.e.,ffh and gsp F),intracellular substrates metabolism(i.e.,ald and paa F)and VFAs biosynthesis(i.e.,ACACA and FASN)were enhanced in the optimal presence of PHMG.Moreover,the anaerobic species could respond and adapt to low PHMG stimuli via quorum sensing(i.e.,cqs A,rpf C and rpf G),and thus maintain the high microbial metabolic activities.However,they were unable to tolerate the toxicity of excessive PHMG,resulting in the extremely low VFAs production.This work enlightened the effects of emerging pollutants on WAS fermentation at the genetic levels,and provided guidance on the WAS treatment and resource recovery.展开更多
基金the Vietnam National Foundation for Science and Technology Development(NAFOSTED)Vietnam under Grant No.(107.01-2019.311).
文摘In this paper,a non-negative adaptive mechanism based on an adaptive nonsingular fast terminal sliding mode control strategy is proposed to have finite time and high-speed trajectory tracking for parallel manipulators with the existence of unknown bounded complex uncertainties and external disturbances.The proposed approach is a hybrid scheme of the online non-negative adaptive mechanism,tracking differentiator,and nonsingular fast terminal sliding mode control(NFTSMC).Based on the online non-negative adaptive mechanism,the proposed control can remove the assumption that the uncertainties and disturbances must be bounded for the NFTSMC controllers.The proposed controller has several advantages such as simple structure,easy implementation,rapid response,chattering-free,high precision,robustness,singularity avoidance,and finite-time convergence.Since all control parameters are online updated via tracking differentiator and non-negative adaptive law,the tracking control performance at high-speed motions can be better in real-time requirement and disturbance rejection ability.Finally,simulation results validate the effectiveness of the proposed method.
基金supported by State Grid Hebei Electric Power Co.,Ltd.Science and Technology Project,Research on Security Protection of Power Services Carried by 4G/5G Networks(Grant No.KJ2024-127).
文摘The rapid growth of Internet of things devices and the emergence of rapidly evolving network threats have made traditional security assessment methods inadequate.Federated learning offers a promising solution to expedite the training of security assessment models.However,ensuring the trustworthiness and robustness of federated learning under multi-party collaboration scenarios remains a challenge.To address these issues,this study proposes a shard aggregation network structure and a malicious node detection mechanism,along with improvements to the federated learning training process.First,we extract the data features of the participants by using spectral clustering methods combined with a Gaussian kernel function.Then,we introduce a multi-objective decision-making approach that combines data distribution consistency,consensus communication overhead,and consensus result reliability in order to determine the final network sharing scheme.Finally,by integrating the federated learning aggregation process with the malicious node detection mechanism,we improve the traditional decentralized learning process.Our proposed ShardFed algorithm outperforms conventional classification algorithms and state-of-the-art machine learning methods like FedProx and FedCurv in convergence speed,robustness against data interference,and adaptability across multiple scenarios.Experimental results demonstrate that the proposed approach improves model accuracy by up to 2.33%under non-independent and identically distributed data conditions,maintains higher performance with malicious nodes containing poisoned data ratios of 20%–50%,and significantly enhances model resistance to low-quality data.
文摘This paper explores the issue of secure synchronization control in piecewise-homogeneous Markovian jump delay neural networks affected by denial-of-service(DoS)attacks.Initially,a novel memory-based adaptive event-triggered mechanism(MBAETM)is designed based on sequential growth rates,focusing on event-triggered conditions and thresholds.Subsequently,from the perspective of defenders,non-periodic DoS attacks are re-characterized,and a model of irregular DoS attacks with cyclic fluctuations within time series is further introduced to enhance the system's defense capabilities more effectively.Additionally,considering the unified demands of network security and communication efficiency,a resilient memory-based adaptive event-triggered mechanism(RMBAETM)is proposed.A unified Lyapunov-Krasovskii functional is then constructed,incorporating a loop functional to thoroughly consider information at trigger moments.The master-slave system achieves synchronization through the application of linear matrix inequality techniques.Finally,the proposed methods'effectiveness and superiority are confirmed through four numerical simulation examples.
基金supported by the National Natural Science Foundation of China(Grant NO.32360307).
文摘Long-term niche differentiation will lead to the evolution of diverse adaptive strategies for species in diverse environments. The present study selected two Forsythia species, Forsythia mandshurica(Fm)-which naturally occurs in a cold temperate zone and Forsythia suspensa(Fs)-which thrives in a warm temperate zone-to reveal their differential chilling defense mechanisms by integrating morpho-physiological,transcriptomic, and metabolomic data. Transcriptome results show that Fm has evolved in a series of adaptive mechanisms designed to help the plants to cope with chilling stress by enhancing sugar, amino acid, hormone, polyamine, and phenol content to improve cell osmotic potential and to mitigate petal browning. Metabolomic data suggested the increased chilling resistance of Fm relies on in the plant being rich in a-linolenic acid, linoleic acid, as well as two amino acids, Phe and Trp, and has low levels of cinnamic acid and gramine in flowers compared to Fs. A higher abundance of glutathione disulfide and NADPH regulated by glutathione peroxidases and NADPH improved the ability of the cellular antioxidant and reduction-oxidation system stability in Fm;Additionally, the elevated levels of pyruvate, a-ketoglutaric acid, and oxaloacetic acid in Fm contributed to a significantly enhanced ATP production in mitochondria. Through Ka/Ks and gene expression analysis,four transcription factors, EVM0025036(bHLH), EVM0010639 and EVM0007275(AP2), and EVM0025908(bZIP) were identified that may contribute to the high cold tolerance of Fm. These adaptations highlight the intricate interplay between genetic and physiological processes that shape the survival strategies of plants in response to their specific ecological niches.
基金The National Natural Science Foundation of China(W2431048)The Science and Technology Research Program of Chongqing Municipal Education Commission,China(KJZDK202300807)The Chongqing Natural Science Foundation,China(CSTB2024NSCQQCXMX0052).
文摘This paper addresses the consensus problem of nonlinear multi-agent systems subject to external disturbances and uncertainties under denial-ofservice(DoS)attacks.Firstly,an observer-based state feedback control method is employed to achieve secure control by estimating the system's state in real time.Secondly,by combining a memory-based adaptive eventtriggered mechanism with neural networks,the paper aims to approximate the nonlinear terms in the networked system and efficiently conserve system resources.Finally,based on a two-degree-of-freedom model of a vehicle affected by crosswinds,this paper constructs a multi-unmanned ground vehicle(Multi-UGV)system to validate the effectiveness of the proposed method.Simulation results show that the proposed control strategy can effectively handle external disturbances such as crosswinds in practical applications,ensuring the stability and reliable operation of the Multi-UGV system.
文摘For survival,bats of the suborder Microchiropetra emit intense ultrasonic pulses and analyze the weak returning echoes to extract the direction,distance,velocity,size,and shape of the prey.Although these bats and other mammals share the common layout of the auditory pathway and sound coding mechanism,they have highly developed auditory systems to process biologically relevant pulses at the expense of a reduced visual system.During this active biosonar behavior,they progressively shorten the pulse duration,decrease the amplitude and pulse-echo gap as they search,approach and finally intercept the prey.Presumably,these changes in multiple pulse parameters throughout the entire course of hunting enable them to extract maximal information about localized prey from the returning echoes.To hunt successfully,the auditory system of these bats must be less sensitive to intense emitted pulses but highly sensitive to weak returning echoes.They also need to recognize and differentiate the echoes of their emitted pulses from echoes of pulses emitted by other conspecifics.Past studies have shown the following mechanical and neural adaptive mechanisms underlying the successful bat biosonar behavior:(1)Forward orienting and highly mobile pinnae for effective scanning,signal reception,sound pressure transformation and mobile auditory sensitivity;(2)Avoiding and detecting moving targets more successfully than stationary ones;(3)Coordinated activity of highly developed laryngeal and middle ear muscles during pulse emission and reception;(4)Mechanical and neural attenuation of intense emitted pulses to prepare for better reception of weak returning echoes;(5)Increasing pulse repetition rate to improve multiple-parametric selectivity to echoes;(6)Dynamic variation of duration selectivity and recovery cycle of auditory neurons with hunting phase for better echo analysis;(7)Maximal multiple-parametric selectivity to expected echoes returning within a time window after pulse emission;(8)Pulse-echo delaysensitive neurons in higher auditory centers for echo ranging;(9)Corticofugal modulation to improve on-going multiple-parametric signal processing and reorganize signal representation,and(10)A large area of the superior colliculus,pontine nuclei and cerebellum that is sensitive to sound for sensori-motor integration.All these adaptive mechanisms facilitate the bat to effectively extract prey features for successful hunting.
基金the National Natural Science Foundation of China(61563032,61963025)The Open Foundation of the Key Laboratory of Gansu Advanced Control for Industrial Processes(2019KX01)The Project of Industrial support and guidance of Colleges and Universities in Gansu Province(2019C05).
文摘In this work,an adaptive sampling control strategy for distributed predictive control is proposed.According to the proposed method,the sampling rate of each subsystem of the accused object is determined based on the periodic detection of its dynamic behavior and calculations made using a correlation function.Then,the optimal sampling interval within the period is obtained and sent to the corresponding sub-prediction controller,and the sampling interval of the controller is changed accordingly before the next sampling period begins.In the next control period,the adaptive sampling mechanism recalculates the sampling rate of each subsystem’s measurable output variable according to both the abovementioned method and the change in the dynamic behavior of the entire system,and this process is repeated.Such an adaptive sampling interval selection based on an autocorrelation function that measures dynamic behavior can dynamically optimize the selection of sampling rate according to the real-time change in the dynamic behavior of the controlled object.It can also accurately capture dynamic changes,meaning that each sub-prediction controller can more accurately calculate the optimal control quantity at the next moment,significantly improving the performance of distributed model predictive control(DMPC).A comparison demonstrates that the proposed adaptive sampling DMPC algorithm has better tracking performance than the traditional DMPC algorithm.
基金supported by the National High Technology Research and Development Program ("863" Program) of China under Grant No. 2007AA01Z209the National Basic Research Program of China under Grant No. 2009CB320405.
文摘According to the basic functions and objectives of Cognitive Radio (CR) systems, the cognition-based adaptive control mechanism is the generalization of the research contents and approaches of cognitive radio systems. Therefore, the mechanism is described by a cognition loop, which contains the following parts: environment, inner structure of intelligent systems, observation and action.
基金supported by the Shandong Provincial Natural Science Foundation(ZR2022QH144).
文摘The phenomenon of fear memory generalization can be defined as the expansion of an individual's originally specific fear responses to a similar yet genuinely harmless stimulus or situation subsequent to the occurrence of a traumatic event[1].Fear generalization within the normal range represents an adaptive evolutionary mechanism to facilitate prompt reactions to potential threats and to enhance the likelihood of survival.
基金financially supported by the National Natural Science Foundation of China(Grant No.61673260)。
文摘Marine current energy has been increasingly used because of its predictable higher power potential.Owing to the external disturbances of various flow velocity and the high nonlinear effects on the marine current turbine(MCT)system,the nonlinear controllers which rely on precise mathematical models show poor performance under a high level of parameters’uncertainties.This paper proposes an adaptive single neural control(ASNC)strategy for variable step-size perturb and observe(P&O)maximum power point tracking(MPPT)control.Firstly,to automatically update the neuron weights of SNC for the nonlinear systems,an adaptive mechanism is proposed to adaptively adjust the weighting and learning coefficients.Secondly,aiming to generate the exact reference speed for ASNC to extract the maximum power,a variable step-size law based on speed increment is designed to strike a balance between tracking speed and accuracy of P&O MPPT.The robust stability of the MCT control system is guaranteed by the Lyapunov theorem.Comparative simulation results show that this strategy has favorable adaptive performance under variable velocity conditions,and the MCT system operates at maximum power point steadily.
基金the National Natural Science Foundation of China(31960222,31360095).
文摘Saussurea medusa,Saussurea hypsipeta and Saussurea obvallata are typical alpine snowline plants growing in the Qinghai-Tibet plateau.They are characterized by a specialized morphology.S.medusa and S.hypsipeta have very dense trichomes on whole plant,whereas S.obvallata has transparent bracts covered inflorescences.The different forms reflect their adaptation to cold environments.To investigate the different mechanisms of adaptation of these species to cold temperatures,transcriptome sequencing was performed in three species of Saussurea DC.A total of 116394137237 and 113879 Unigenes were identified from S.medusa,S.hypsipeta and S.obvallata,respectively.Of these,55909(48.03%),65519(47.74%)and 51889(45.56%)Unigenes were matched in public databases.GO analysis identified that most of annotated Unigenes in the three species of plants were related to cellular,metabolic,and single−organism processes,and binding and catalytic activities.The differential expression of 37 genes related to environmental adaptation were discovered by pairwise comparisons.Of these,two candidate genes(Interaptin-like and CSLB3)related to trichome development were identified only in S.medusa and S.hypsipeta,which was consistent with their distinct morphology.Our data can provide a valuable resource for the further studies on the adaptive mechanisms of molecular and functional ecology in Saussurea DC.
基金Supported by Outstanding Youth Project of Hunan Provincial Education Department(18B461)Hunan Science and Technology Innovation Program(2019NK4170).
文摘Erigeron annuus(L.)Pers.,an alien species,is widely distributed in most areas of China.It was included in the third batch of invasive alien species list by the Ministry of Ecology and Environment of China,and it is a first-level malignant invasive plant.Due to its great reproducibility with a mass of seeds,power adaptability to the external environment and strong allelopathy,it has highly invasive and adaptability,and has affected the development of the agriculture and forestry,the diversity of local species and the ecosystem.In this paper,we summarized the current invasion situation,invasion and adaptation mechanism of E.annuus,and prospected further research on E.annuus invasion mechanism,hoping to provide a reference for realizing its effective management.
文摘The Polar Regions host one of the harshest and most unique ecosystems on Earth,harboring a diverse array of micro-and macro-organisms.These inhabitants showcase remarkable taxonomic and genetic originality,presenting unparalleled opportunities for bioprospecting,alongside demonstrating extraordinary adaptation mechanisms for survival.Furthermore,polar organisms play crucial roles in facilitating organic matter decomposition,carbon fixation and sequestration,and biogeochemical cycling.Moreover,these organisms serve as pivotal indicators of global climate shifts.Therefore,exploring the polar organisms and ecosystem holds profound and significant implications for gaining deeper insights into scientific frontiers such as global biodiversity,elementary cycling,climate change,resource utilization,and the awe of life in extreme environments.
基金supported by the National Natural Science Foundation of China(61773056)the Scientific and Technological Innovation Foundation of Shunde Graduate School,University of Science and Technology Beijing(USTB)(BK19AE018)+2 种基金the Fundamental Research Funds for the Central Universities of USTB(FRF-TP-20-09B,230201606500061,FRF-DF-20-35,FRF-BD-19-002A)supported by Zhejiang Natural Science Foundation(LD21F030001)supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(Ministry of Science and Information and Communications Technology)(NRF-2020R1A2C1005449)。
文摘This paper investigates the event-triggered security consensus problem for nonlinear multi-agent systems(MASs)under denial-of-service(Do S)attacks over an undirected graph.A novel adaptive memory observer-based anti-disturbance control scheme is presented to improve the observer accuracy by adding a buffer for the system output measurements.Meanwhile,this control scheme can also provide more reasonable control signals when Do S attacks occur.To save network resources,an adaptive memory event-triggered mechanism(AMETM)is also proposed and Zeno behavior is excluded.It is worth mentioning that the AMETM's updates do not require global information.Then,the observer and controller gains are obtained by using the linear matrix inequality(LMI)technique.Finally,simulation examples show the effectiveness of the proposed control scheme.
基金Project supported by the Natural Science Foundation of Yangzhou University of China （Grant No KK0513109）.
文摘In this paper, an approach to the control of continuous-time chaotic systems is proposed using the Takagi-Sugeno （TS） fuzzy model and adaptive adjustment. Sufficient conditions are derived to guarantee chaos control from Lyapunov stability theory. The proposed approach offers a systematic design procedure for stabilizing a large class of chaotic systems in the literature about chaos research. The simulation results on Rossler＇s system verify the effectiveness of the proposed methods.
文摘Molecular mechanisms of plant responses to salinity stress and the physiological consequences of altered gene expression are reviewed. Extensive use of comparisons with halophytic plants and glycophytos provide a paradigm for many responses to salinity exhibited by stress sensitive plants. Osmolyte biosynthesis, water flux control, and membrane transport of ions are important for maintenance and re-establishment of homeostasis. Transgenic plant and mutant analyses in Arabidopsis improve the understanding of stress responses and elements of stress signal transduction pathways. The genomic DNA sequences and cell-specific transcript expression data, combined with determinant identification based on molecular genetics, will provide the infrastructure for functional physiological dissection of salt tolerance determinants in plants. Protein interaction analysis, genetic activation and suppression screens will lead inevitably to an understanding of the interrelationships of the multiple signaling systems that control stress-adaptive responses and provide more opportunity to engineer salt tolerance in plants.
基金sponsored by the National Natural Science Foundation of China(52105269).
文摘For the randomness of crane working load leading to the decrease of load spectrum prediction accuracy with time,an adaptive TSSA-HKRVM model for crane load spectrum regression prediction is proposed.The heterogeneous kernel relevance vector machine model(HKRVM)with comprehensive expression ability is established using the complementary advantages of various kernel functions.The combination strategy consisting of refraction reverse learning,golden sine,and Cauchy mutation+logistic chaotic perturbation is introduced to form a multi-strategy improved sparrow algorithm(TSSA),thus optimizing the relevant parameters of HKRVM.The adaptive updatingmechanismof the heterogeneous kernel RVMmodel under themulti-strategy improved sparrow algorithm(TSSA-HKMRVM)is defined by the sliding window design theory.Based on the sample data of the measured load spectrum,the trained adaptive TSSA-HKRVMmodel is employed to complete the prediction of the crane equivalent load spectrum.Applying this method toQD20/10 t×43m×12mgeneral bridge crane,the results show that:compared with other prediction models,although the complexity of the adaptive TSSA-HKRVMmodel is relatively high,the prediction accuracy of the load spectrum under long periods has been effectively improved,and the completeness of the load information during thewhole life cycle is relatively higher,with better applicability.
基金Project supported by the National Natural Science Foundation of China(Nos.62203306 and 61933007)the Shanghai Pujiang Program,China(No.22PJ1412600)the China Postdoctoral Science Foundation(No.2021M702195)。
文摘Cyber-physical systems(CPSs)take on the characteristics of both multiple rates of information collection and processing and the dependency on information exchanges.The purpose of this paper is to develop a joint recursive filtering scheme that estimates both unknown inputs and system states for multi-rate CPSs with unknown inputs.In cyberspace,the information transmission between the local joint filter and the sensors is governed by an adaptive event-triggered strategy.Furthermore,the desired parameters of joint filters are determined by a set of algebraic matrix equations in a recursive way,and a sufficient condition verifying the boundedness of filtering error covariance is found by resorting to some algebraic operation.A state fusion estimation scheme that uses local state estimation is proposed based on the covariance intersection(CI)based fusion conception.Lastly,an illustrative example demonstrates the effectiveness of the proposed adaptive event-triggered recursive filtering algorithm.
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financially supported by the National Natural Science Foundation of China(No.52070069)Jiangsu Province Natural Science Foundation(No.BK20211207)+3 种基金China Postdoctoral Science Foundation(No.2021M692423)Shanghai Post-doctoral Excellence Program(No.2020419)State Key Laboratory of Pollution Control and Resource Reuse Foundation(No.PCRRF20005)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),China。
文摘The massive use of polyhexamethylene guanidine(PHMG),as a typical bactericidal agent,raised environmental concerns to the public.This work comprehensively revealed the hormesis effects of PHMG occurred in waste activated sludge(WAS)on the generation of volatile fatty acids(VFAs)during anaerobic fermentation.The low level of PHMG(100 mg/g TSS)significantly promoted the VFAs generation(1283 mg COD/L,compared with 337 mg COD/L in the control)via synchronously facilitating the solubilization,hydrolysis,and acidification steps but inhibiting methanogenesis.Metagenomic analysis showed that the functional anaerobe(i.e.,Bacteroides,Macellibacteroide and Parabacteroide)and corresponding genetic expressions responsible for extracellular hydrolysis(i.e.,clp P),membrane transport(i.e.,ffh and gsp F),intracellular substrates metabolism(i.e.,ald and paa F)and VFAs biosynthesis(i.e.,ACACA and FASN)were enhanced in the optimal presence of PHMG.Moreover,the anaerobic species could respond and adapt to low PHMG stimuli via quorum sensing(i.e.,cqs A,rpf C and rpf G),and thus maintain the high microbial metabolic activities.However,they were unable to tolerate the toxicity of excessive PHMG,resulting in the extremely low VFAs production.This work enlightened the effects of emerging pollutants on WAS fermentation at the genetic levels,and provided guidance on the WAS treatment and resource recovery.
