This paper studies the problem of fixed-time output consensus tracking for high-order multi-agent systems(MASs)with directed network topology with consideration of data packet dropout.First,a predictive compensation b...This paper studies the problem of fixed-time output consensus tracking for high-order multi-agent systems(MASs)with directed network topology with consideration of data packet dropout.First,a predictive compensation based distributed observer is presented to compensate for packet dropout and estimate the leader’s states.Next,stability analysis is conducted to prove fixed time convergence of the developed distributed observer.Then,adaptive fixed-time dynamic surface control is designed to counteract mismatched disturbances introduced by observation error,and stabilize the tracking error system within a fixed time,which overcomes explosion of complexity problem and singularity problem.Finally,simulation results are provided to verify the effectiveness and superiority of the consensus tracking strategy proposed.The contribution of this paper is to provide a fixed-time distributed observer design method for high-order MAS under directed graph subject to packet dropout,and a novel fixed-time control strategy which can handle mismatched disturbances and overcome explosion of complexity and singularity problem.展开更多
This article deals with the consensus problem of multi-agent systems by developing a fixed-time consensus control approach with a dynamic event-triggered rule. First, a new fixedtime stability condition is obtained wh...This article deals with the consensus problem of multi-agent systems by developing a fixed-time consensus control approach with a dynamic event-triggered rule. First, a new fixedtime stability condition is obtained where the less conservative settling time is given such that the theoretical settling time can well reflect the real consensus time. Second, a dynamic event-triggered rule is designed to decrease the use of chip and network resources where Zeno behaviors can be avoided after consensus is achieved, especially for finite/fixed-time consensus control approaches. Third, in terms of the developed dynamic event-triggered rule, a fixed-time consensus control approach by introducing a new item is proposed to coordinate the multi-agent system to reach consensus. The corresponding stability of the multi-agent system with the proposed control approach and dynamic eventtriggered rule is analyzed based on Lyapunov theory and the fixed-time stability theorem. At last, the effectiveness of the dynamic event-triggered fixed-time consensus control approach is verified by simulations and experiments for the problem of magnetic map construction based on multiple mobile robots.展开更多
This paper is concerned with bipartite consensus tracking for multi-agent systems with unknown disturbances.A barrier function-based adaptive sliding-mode control(SMC)approach is proposed such that the bipartite stead...This paper is concerned with bipartite consensus tracking for multi-agent systems with unknown disturbances.A barrier function-based adaptive sliding-mode control(SMC)approach is proposed such that the bipartite steady-state error is converged to a predefined region of zero in finite time.Specifically,based on an error auxiliary taking neighboring antagonistic interactions into account,an SMC law is designed with an adaptive gain.The gain can switch to a positive semi-definite barrier function to ensure that the error auxiliary is constrained to a predefined neighborhood of zero,which in turn guarantees practical bipartite consensus tracking.A distinguished feature of the proposed controller is its independence on the bound of disturbances,while the input chattering phenomenon is alleviated.Finally,a numerical example is provided to verify the effectiveness of the proposed controller.展开更多
The problem of fixed-time group consensus for second-order multi-agent systems with disturbances is investigated.For cooperative-competitive network,two different control protocols,fixed-time group consensus and fixed...The problem of fixed-time group consensus for second-order multi-agent systems with disturbances is investigated.For cooperative-competitive network,two different control protocols,fixed-time group consensus and fixed-time eventtriggered group consensus,are designed.It is demonstrated that there is no Zeno behavior under the designed eventtriggered control.Meanwhile,it is proved that for an arbitrary initial state of the system,group consensus within the settling time could be obtained under the proposed control protocols by using matrix analysis and graph theory.Finally,a series of numerical examples are propounded to illustrate the performance of the proposed control protocol.展开更多
To address fixed-time consensus problems of a class of leader-follower second-order nonlinear multi-agent systems with uncertain external disturbances,the event-triggered fixed-time consensus protocol is proposed.Firs...To address fixed-time consensus problems of a class of leader-follower second-order nonlinear multi-agent systems with uncertain external disturbances,the event-triggered fixed-time consensus protocol is proposed.First,the virtual velocity is designed based on the backstepping control method to achieve the system consensus and the bound on convergence time only depending on the system parameters.Second,an event-triggered mechanism is presented to solve the problem of frequent communication between agents,and triggered condition based on state information is given for each follower.It is available to save communication resources,and the Zeno behaviors are excluded.Then,the delay and switching topologies of the system are also discussed.Next,the system stabilization is analyzed by Lyapunov stability theory.Finally,simulation results demonstrate the validity of the presented method.展开更多
In this paper,fixed-time consensus tracking for mul-tiagent systems(MASs)with dynamics in the form of strict feed-back affine nonlinearity is addressed.A fixed-time antidistur-bance consensus tracking protocol is prop...In this paper,fixed-time consensus tracking for mul-tiagent systems(MASs)with dynamics in the form of strict feed-back affine nonlinearity is addressed.A fixed-time antidistur-bance consensus tracking protocol is proposed,which consists of a distributed fixed-time observer,a fixed-time disturbance observer,a nonsmooth antidisturbance backstepping controller,and the fixed-time stability analysis is conducted by using the Lyapunov theory correspondingly.This paper includes three main improvements.First,a distributed fixed-time observer is developed for each follower to obtain an estimate of the leader’s output by utilizing the topology of the communication network.Second,a fixed-time disturbance observer is given to estimate the lumped disturbances for feedforward compensation.Finally,a nonsmooth antidisturbance backstepping tracking controller with feedforward compensation for lumped disturbances is designed.In order to mitigate the“explosion of complexity”in the tradi-tional backstepping approach,we have implemented a modified nonsmooth command filter to enhance the performance of the closed-loop system.The simulation results show that the pro-posed method is effective.展开更多
Polycystic ovary syndrome （PCOS） is the most common metabolic and endocrine disorder in women. However, there is no agreement concerning how to diagnose and treat PCOS worldwide. Three practice guidelines or consens...Polycystic ovary syndrome （PCOS） is the most common metabolic and endocrine disorder in women. However, there is no agreement concerning how to diagnose and treat PCOS worldwide. Three practice guidelines or consensuses, including consensus from the European Society of Human Reproduction and Embryology （ESHRE）/the American Society for Reproductive Medicine （ASRM） in Rotterdam, diagnosis criteria and consensus in China, and clinical practice guideline from the Endocrine Society （ES） in the United States are widely recognized. The present paper may provide some guidance for clinical practice based on a comparative analysis of the above three practice guidelines or consensuses.展开更多
Objective:To establish consensus on Chinese Herbal Medicine(CHM)for rheumatoid arthritis(RA)among 21 Singaporean experts,this study addressed the lack of CHM clinical practice guidelines(CPGs)in Singapore.Despite adva...Objective:To establish consensus on Chinese Herbal Medicine(CHM)for rheumatoid arthritis(RA)among 21 Singaporean experts,this study addressed the lack of CHM clinical practice guidelines(CPGs)in Singapore.Despite advancements in RA therapies,the disease's progressive nature and high costs of novel treatments worsen disparities in management and outcomes.The initiative aimed to bridge this gap by developing expert-backed recommendations for CHM use in RA care.Methods:The group of experts conducted two rounds of Delphi surveys containing 29 items identified from a literature review.Consensus was defined as≥75%of votes in dichotomized ratings on a fivepoint ordinal scale for recognition.Items that did not reach consensus were discussed in a focus group with four selected experts.Results:Nineteen experts completed both rounds of Delphi surveys.A consensus was reached for 27 items,which encompassed Chinese medicine rationale,pattern differentiation,management,CHM prescription,and co-effectiveness with pharmacological therapy.Collective expert opinions were formed for the two remaining items.All items received a recognition score>3.5.Conclusions:The consensus derived from this study provides a foundation for CHM CPGs for RA in Singapore.However,the findings are limited by the demographic composition of the experts and the representativeness of the patient pool.展开更多
There has been significant recent research on secure control problems that arise from the open and complex realworld industrial environments.This paper focuses on addressing the issue of secure consensus control in mu...There has been significant recent research on secure control problems that arise from the open and complex realworld industrial environments.This paper focuses on addressing the issue of secure consensus control in multi-agent systems(MASs)under malicious attacks,utilizing the practical Byzantine fault tolerance(PBFT)and Raft consensus algorithm in blockchain.Unlike existing secure consensus control algorithms that have strict requirements for topology and high communication costs,our approach introduces a node grouping methodology based on system topology.Additionally,we utilize the PBFT consensus algorithm for intergroup leader identity verification,effectively reducing the communication complexity of PBFT in large-scale networks.Furthermore,we enhance the Raft algorithm through cryptographic validation during followers’log replication,which enhances the security of the system.Our proposed consensus process not only identifies the identities of malicious agents but also ensures consensus among normal agents.Through extensive simulations,we demonstrate robust convergence,particularly in scenarios with the relaxed topological requirements.Comparative experiments also validate the algorithm’s lower consensus latency and improved efficiency compared to direct PBFT utilization for identity verification and classical secure consensus control method mean subsequence reduced(MSR)algorithm.展开更多
Through three millennia of practice,Traditional Chinese Medicine(TCM)has evolved by integrating knowledge from diverse disciplines,forging a distinct developmental path that respects its ancient foundations while inco...Through three millennia of practice,Traditional Chinese Medicine(TCM)has evolved by integrating knowledge from diverse disciplines,forging a distinct developmental path that respects its ancient foundations while incorporating innovation.TCM has achieved significant breakthroughs in elucidating its theoretical foundations using contemporary scientific methodologies,through the implementation of modernization initiatives over the past three decades.The TCM modernization program has yielded continuous innovations,propelling TCM into a high-quality development stage across both clinical practice and industrial applications.Notably,these advances have enhanced global recognition and adoption of TCM.展开更多
AIM To determine the application of clinical practice guidelines for the current management of diverticulitis and colorectal surgeon specialist consensus in Australia and New Zealand.METHODS A survey was distributed t...AIM To determine the application of clinical practice guidelines for the current management of diverticulitis and colorectal surgeon specialist consensus in Australia and New Zealand.METHODS A survey was distributed to 205 colorectal surgeons in Australia and New Zealand, using 22 hypothetical clinical scenarios.RESULTS The response rate was 102(50%). For 19 guidelinebased scenarios, only 11(58%) reached consensus(defined as > 70% majority opinion) and agreed with guidelines; while 3(16%) reached consensus and did not agree with guidelines. The remaining 5(26%) scenarios showed community equipoise(defined as less than/equal to 70% majority opinion). These included diagnostic imaging where CT scan was contraindicated, management options in the failureof conservative therapy for complicated diverticulitis, surgical management of Hinchey grade 3, proximal extent of resection in sigmoid diverticulitis and use of oral mechanical bowel preparation and antibiotics for an elective colectomy. The consensus areas not agreeing with guidelines were management of simple diverticulitis, management following the failure of conservative therapy in uncomplicated diverticulitis and follow-up after an episode of complicated diverticulitis. Fifty-percent of rural/regional based surgeons would perform an urgent sigmoid colectomy in failed conservative therapy of diverticulitis compared to only 8% of surgeons city-based(Fisher's exact test P = 0.016). In right-sided complicated diverticulitis, a greater number of those in practice for more than ten years would perform an ileocecal resection and ileocolic anastomosis(79% vs 41%, P < 0.0001).CONCLUSION While there are areas of consensus in diverticulitis management, there are areas of community equipoise for future research, potentially in the form of RCTs.展开更多
I. The Value Tyranny of the Universality of Western Human Rights Discourse From the perspective of history, human rights discourse originating in the West is first of all a kind of special discourse, rather than unive...I. The Value Tyranny of the Universality of Western Human Rights Discourse From the perspective of history, human rights discourse originating in the West is first of all a kind of special discourse, rather than universal words. ＂Human rights discourse is a language of rights, which is a language of Western culture. Therefore, in terms of concept, there is no concept of ＇human rights＇ in traditional Confucianism, not even the concept of ＇rights＇. In this sense, the concept ＇human rights＇ is a product of typical Western culture, although it appeared in modern times and it was the out- come of the development of civil society and democracy.TM Marked by unique Western color, human rights discourse originated from the special Western economic, political, histori- cal and cultural background and has its unique consciousness of problems and practical direction. For example,展开更多
In this paper,a fixed-time optimized control scheme with prescribed performance is presented for bipartite consensus of nonlinear multi-agent systems(MASs).To enforce predefined transient and steady-state performance ...In this paper,a fixed-time optimized control scheme with prescribed performance is presented for bipartite consensus of nonlinear multi-agent systems(MASs).To enforce predefined transient and steady-state performance within a fixed time,a fixed-time prescribed performance function(FTPPF)is introduced.The control design is achieved via an identifier-actor-critic framework that approximates the solution to the Hamilton-Jacobi-Bellman equation.Unknown system dynamics are compensated by fuzzy logic systems,and a rounding quantizer processes the signal of the leader to reduce the communication costs.The proposed method ensures all consensus errors converge with prescribed performance bounds in a fixed time.Simulation results validate the theoretical findings.展开更多
In this paper, the fixed-time event-triggered obstacle avoidance consensus control for a multi-AUV time-varying formation system in a 3D environment is presented by using an improved artificial potential field and lea...In this paper, the fixed-time event-triggered obstacle avoidance consensus control for a multi-AUV time-varying formation system in a 3D environment is presented by using an improved artificial potential field and leader-follower strategy(IAPF-LF). Firstly, the proposed fixed-time control can achieve the desired multi-AUV formation within a fixed settling time in any initial system state. Secondly, an event-triggered communication strategy is developed to govern the communication among AUVs, and the communication energy consumption can be decremented. The time-varying formation obstacle avoidance control algorithm based on IAPF-LF is designed to avoid static and dynamic obstacles, the desired formation is maintained in the presence of external disturbances, and there is no Zeno behavior under the fixed-time event-triggered consensus control strategy.The stability of the system is proved by the Lyapunov function and inequality scaling. Finally, simulation examples and water pool experiments are reported to verify the performance of the proposed theoretical algorithms.展开更多
Blockchain is a distributed public ledger that keeps track of all transactions that have ever taken place in the system. As a distributed ledger, a consensus mechanism is required to ensure all the transaction functio...Blockchain is a distributed public ledger that keeps track of all transactions that have ever taken place in the system. As a distributed ledger, a consensus mechanism is required to ensure all the transaction functions properly. In order to reach a consensus, it is critical to emphasize the importance of performance and efficiency. The use of the right consensus algorithm will significantly improve the efficiency of a blockchain application. This paper reviewed several types of consensus algorithms used in blockchain and discusses the idea of a new consensus algorithm that can improve the performance of consortium blockchain.展开更多
The article investigates the optimal energy management(OEM)problem for microgrids.To figure out the problem in fixed time and alleviate communication load with limited resources,this article devises a novel fixed-time...The article investigates the optimal energy management(OEM)problem for microgrids.To figure out the problem in fixed time and alleviate communication load with limited resources,this article devises a novel fixed-time stability lemma and an event-triggered(ET)fixed-time distributed OEM approach.Using Lyapunov stability theory,the distributed approach has been proven to converge in fixed time and the upper bound on convergence time can be derived without dependence on the initial states.The dynamic ET method is raised to dynamically adjust the triggering threshold and reduce communication redundancy.In addition,Zeno behavior is avoided.Simulations are given to show the effectiveness and advantage of the designed distributed OEM method.展开更多
The accelerated method in solving optimization problems has always been an absorbing topic.Based on the fixedtime(FxT)stability of nonlinear dynamical systems,we provide a unified approach for designing FxT gradient f...The accelerated method in solving optimization problems has always been an absorbing topic.Based on the fixedtime(FxT)stability of nonlinear dynamical systems,we provide a unified approach for designing FxT gradient flows(FxTGFs).First,a general class of nonlinear functions in designing FxTGFs is provided.A unified method for designing first-order FxTGFs is shown under Polyak-Łjasiewicz inequality assumption,a weaker condition than strong convexity.When there exist both bounded and vanishing disturbances in the gradient flow,a specific class of nonsmooth robust FxTGFs with disturbance rejection is presented.Under the strict convexity assumption,Newton-based FxTGFs is given and further extended to solve time-varying optimization.Besides,the proposed FxTGFs are further used for solving equation-constrained optimization.Moreover,an FxT proximal gradient flow with a wide range of parameters is provided for solving nonsmooth composite optimization.To show the effectiveness of various FxTGFs,the static regret analyses for several typical FxTGFs are also provided in detail.Finally,the proposed FxTGFs are applied to solve two network problems,i.e.,the network consensus problem and solving a system linear equations,respectively,from the perspective of optimization.Particularly,by choosing component-wisely sign-preserving functions,these problems can be solved in a distributed way,which extends the existing results.The accelerated convergence and robustness of the proposed FxTGFs are validated in several numerical examples stemming from practical applications.展开更多
The PBFT (Practical Byzantine Fault Tolerance, PBFT) consensus algorithm, which addressed the issue of malicious nodes sending error messages to disrupt the system operation in distributed systems, was challenging to ...The PBFT (Practical Byzantine Fault Tolerance, PBFT) consensus algorithm, which addressed the issue of malicious nodes sending error messages to disrupt the system operation in distributed systems, was challenging to support massive network nodes, the common participation over all nodes in the consensus mechanism would lead to increased communication complexity, and the arbitrary selection of master nodes would also lead to inefficient consensus. This paper offered a PBFT consensus method (Role Division-based Practical Byzantine Fault Tolerance, RD-PBFT) to address the above problems based on node role division. First, the nodes in the system voted with each other to divide the high reputation group and low reputation group, and determined the starting reputation value of the nodes. Then, the mobile node in the group was divided into roles according to the high reputation value, and a total of three roles were divided into consensus node, backup node, and supervisory node to reduce the number of nodes involved in the consensus process and reduced the complexity of communication. In addition, an adaptive method was used to select the master nodes in the consensus process, and an integer value was introduced to ensure the unpredictability and equality of the master node selection. Experimentally, it was verified that the algorithm has lower communication complexity and better decentralization characteristics compared with the PBFT consensus algorithm, which improved the efficiency of consensus.展开更多
This study conducts a systematic literature review(SLR)of blockchain consensus mechanisms,an essential protocols that maintain the integrity,reliability,and decentralization of distributed ledger networks.The aim is t...This study conducts a systematic literature review(SLR)of blockchain consensus mechanisms,an essential protocols that maintain the integrity,reliability,and decentralization of distributed ledger networks.The aim is to comprehensively investigate prominent mechanisms’security features and vulnerabilities,emphasizing their security considerations,applications,challenges,and future directions.The existing literature offers valuable insights into various consensus mechanisms’strengths,limitations,and security vulnerabilities and their real-world applications.However,there remains a gap in synthesizing and analyzing this knowledge systematically.Addressing this gap would facilitate a structured approach to understanding consensus mechanisms’security and vulnerabilities comprehensively.The study adheres to Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)guidelines and computer science standards and reviewed 3749 research papers from 2016 to 2024,excluding grey literature,resulting in 290 articles for descriptive analysis.The research highlights an increased focus on blockchain consensus security,energy efficiency,and hybrid mechanisms within 60%of research papers post-2019,identifying gaps in scalability,privacy,and interoperability for future exploration.By synthesizing the existing research and identifying the key trends,this SLR contributes to advancing the understanding of blockchain consensus mechanisms’security and guiding future research and structured innovation in blockchain systems and applications.展开更多
This paper addresses the problem of achieving practical consensus in large-scale agent clusters governed by nonlinear reaction-diffusion equations,while considering actuator saturation and external disturbances.Differ...This paper addresses the problem of achieving practical consensus in large-scale agent clusters governed by nonlinear reaction-diffusion equations,while considering actuator saturation and external disturbances.Different with the traditional consensus methods,the proposed observer-based boundary control relies on non-collocated and incomplete local measurements rather than idealistic global spatiotemporal dynamics.First,the discrete agents with a chain topology are regarded as a continuum,resulting in the derivation of a reaction-diffusion equation to replace the cumbersome ordinary differential equations(ODEs).Subsequently,an observer is constructed based on the non-collocated measurements to estimate the errors between the leader-following agent clusters.Then,a sufficient condition for the consensus controller is derived by improving the Lyapunov direct method,mean value theorem of integrals and a variation of Wirtinger's inequality.Furthermore,an optimization problem is proposed to effectively enhance the H_(∞)disturbance attenuation performance in the presence of actuator saturation.Finally,the comparison simulation is given to illustrate the superiority of proposed methodology.展开更多
基金supported in part by the National Natural Science Foundation of China(61903302,61973252,61903126)the Natural Science Basic Research Plan in Shaanxi Province of China(2019JQ-035)+2 种基金the Fundamental Research Funds for the Central Universities(31020180QD076,ZDHXYKYYW201914)Key R&D and Promotion Projects in Henan Province(202102210130)Key Scientific Research Projects of Universities in Henan Province-20A590001。
文摘This paper studies the problem of fixed-time output consensus tracking for high-order multi-agent systems(MASs)with directed network topology with consideration of data packet dropout.First,a predictive compensation based distributed observer is presented to compensate for packet dropout and estimate the leader’s states.Next,stability analysis is conducted to prove fixed time convergence of the developed distributed observer.Then,adaptive fixed-time dynamic surface control is designed to counteract mismatched disturbances introduced by observation error,and stabilize the tracking error system within a fixed time,which overcomes explosion of complexity problem and singularity problem.Finally,simulation results are provided to verify the effectiveness and superiority of the consensus tracking strategy proposed.The contribution of this paper is to provide a fixed-time distributed observer design method for high-order MAS under directed graph subject to packet dropout,and a novel fixed-time control strategy which can handle mismatched disturbances and overcome explosion of complexity and singularity problem.
基金supported in part by the National Natural Science Foundation of China (62073108)the Zhejiang Provincial Natural Science Foundation(LZ23F030004)+1 种基金the Key Research and Development Project of Zhejiang Province (2019C04018)the Fundamental Research Funds for the Provincial Universities of Zhejiang (GK229909299001-004)。
文摘This article deals with the consensus problem of multi-agent systems by developing a fixed-time consensus control approach with a dynamic event-triggered rule. First, a new fixedtime stability condition is obtained where the less conservative settling time is given such that the theoretical settling time can well reflect the real consensus time. Second, a dynamic event-triggered rule is designed to decrease the use of chip and network resources where Zeno behaviors can be avoided after consensus is achieved, especially for finite/fixed-time consensus control approaches. Third, in terms of the developed dynamic event-triggered rule, a fixed-time consensus control approach by introducing a new item is proposed to coordinate the multi-agent system to reach consensus. The corresponding stability of the multi-agent system with the proposed control approach and dynamic eventtriggered rule is analyzed based on Lyapunov theory and the fixed-time stability theorem. At last, the effectiveness of the dynamic event-triggered fixed-time consensus control approach is verified by simulations and experiments for the problem of magnetic map construction based on multiple mobile robots.
文摘This paper is concerned with bipartite consensus tracking for multi-agent systems with unknown disturbances.A barrier function-based adaptive sliding-mode control(SMC)approach is proposed such that the bipartite steady-state error is converged to a predefined region of zero in finite time.Specifically,based on an error auxiliary taking neighboring antagonistic interactions into account,an SMC law is designed with an adaptive gain.The gain can switch to a positive semi-definite barrier function to ensure that the error auxiliary is constrained to a predefined neighborhood of zero,which in turn guarantees practical bipartite consensus tracking.A distinguished feature of the proposed controller is its independence on the bound of disturbances,while the input chattering phenomenon is alleviated.Finally,a numerical example is provided to verify the effectiveness of the proposed controller.
基金Project supported by the Graduate Student Research Innovation Project of Chongqing(Grant No.CYS22482)the National Natural Science Foundation of China(Grant No.61773082)+1 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K202000601)the Research Program of Chongqing Talent,China(Grant No.cstc2021ycjhbgzxm0044).
文摘The problem of fixed-time group consensus for second-order multi-agent systems with disturbances is investigated.For cooperative-competitive network,two different control protocols,fixed-time group consensus and fixed-time eventtriggered group consensus,are designed.It is demonstrated that there is no Zeno behavior under the designed eventtriggered control.Meanwhile,it is proved that for an arbitrary initial state of the system,group consensus within the settling time could be obtained under the proposed control protocols by using matrix analysis and graph theory.Finally,a series of numerical examples are propounded to illustrate the performance of the proposed control protocol.
基金National Natural Science Foundation of China(No.62073296)Natural Science Foundation of Zhejiang Province,China(No.LZ23F030010)Key Laboratory of Intelligent Manufacturing Quality Big Data Tracing and Analysis of Zhejiang Province,China Jiliang University(No.ZNZZSZ-CJLU2022-03)Rights and permissions。
文摘To address fixed-time consensus problems of a class of leader-follower second-order nonlinear multi-agent systems with uncertain external disturbances,the event-triggered fixed-time consensus protocol is proposed.First,the virtual velocity is designed based on the backstepping control method to achieve the system consensus and the bound on convergence time only depending on the system parameters.Second,an event-triggered mechanism is presented to solve the problem of frequent communication between agents,and triggered condition based on state information is given for each follower.It is available to save communication resources,and the Zeno behaviors are excluded.Then,the delay and switching topologies of the system are also discussed.Next,the system stabilization is analyzed by Lyapunov stability theory.Finally,simulation results demonstrate the validity of the presented method.
基金supported by the National Defense Basic Scientific Research Project(JCKY2020130C025)the National Science and Technology Major Project(J2019-III-0020-0064,J2019-V-0014-0109)。
文摘In this paper,fixed-time consensus tracking for mul-tiagent systems(MASs)with dynamics in the form of strict feed-back affine nonlinearity is addressed.A fixed-time antidistur-bance consensus tracking protocol is proposed,which consists of a distributed fixed-time observer,a fixed-time disturbance observer,a nonsmooth antidisturbance backstepping controller,and the fixed-time stability analysis is conducted by using the Lyapunov theory correspondingly.This paper includes three main improvements.First,a distributed fixed-time observer is developed for each follower to obtain an estimate of the leader’s output by utilizing the topology of the communication network.Second,a fixed-time disturbance observer is given to estimate the lumped disturbances for feedforward compensation.Finally,a nonsmooth antidisturbance backstepping tracking controller with feedforward compensation for lumped disturbances is designed.In order to mitigate the“explosion of complexity”in the tradi-tional backstepping approach,we have implemented a modified nonsmooth command filter to enhance the performance of the closed-loop system.The simulation results show that the pro-posed method is effective.
基金Project supported by the Zhejiang Province Science Foundation for Distinguished Young Scholars(No.LR16H040001)the National Natural Science Foundation of China(No.81401167)+1 种基金Medical and Health General Project of Zhejiang Province,China(No.2015KYA122)the Zhejiang Traditional Chinese Medicine Foundation(Nos.2017ZQ020 and 2017ZA091),China
文摘Polycystic ovary syndrome （PCOS） is the most common metabolic and endocrine disorder in women. However, there is no agreement concerning how to diagnose and treat PCOS worldwide. Three practice guidelines or consensuses, including consensus from the European Society of Human Reproduction and Embryology （ESHRE）/the American Society for Reproductive Medicine （ASRM） in Rotterdam, diagnosis criteria and consensus in China, and clinical practice guideline from the Endocrine Society （ES） in the United States are widely recognized. The present paper may provide some guidance for clinical practice based on a comparative analysis of the above three practice guidelines or consensuses.
基金supported by the Nanyang Technological University Start-Up Grant(#022387‒00001).
文摘Objective:To establish consensus on Chinese Herbal Medicine(CHM)for rheumatoid arthritis(RA)among 21 Singaporean experts,this study addressed the lack of CHM clinical practice guidelines(CPGs)in Singapore.Despite advancements in RA therapies,the disease's progressive nature and high costs of novel treatments worsen disparities in management and outcomes.The initiative aimed to bridge this gap by developing expert-backed recommendations for CHM use in RA care.Methods:The group of experts conducted two rounds of Delphi surveys containing 29 items identified from a literature review.Consensus was defined as≥75%of votes in dichotomized ratings on a fivepoint ordinal scale for recognition.Items that did not reach consensus were discussed in a focus group with four selected experts.Results:Nineteen experts completed both rounds of Delphi surveys.A consensus was reached for 27 items,which encompassed Chinese medicine rationale,pattern differentiation,management,CHM prescription,and co-effectiveness with pharmacological therapy.Collective expert opinions were formed for the two remaining items.All items received a recognition score>3.5.Conclusions:The consensus derived from this study provides a foundation for CHM CPGs for RA in Singapore.However,the findings are limited by the demographic composition of the experts and the representativeness of the patient pool.
基金supported by the Fundamental Research Funds for the Central Universities(NS2024021)the Science and Technology Development Fund of Macao SAR(0145/2023/RIA3,0093/2023/RIA2,0050/2020/A1)the National Natural Science Foundation of China(62103411).
文摘There has been significant recent research on secure control problems that arise from the open and complex realworld industrial environments.This paper focuses on addressing the issue of secure consensus control in multi-agent systems(MASs)under malicious attacks,utilizing the practical Byzantine fault tolerance(PBFT)and Raft consensus algorithm in blockchain.Unlike existing secure consensus control algorithms that have strict requirements for topology and high communication costs,our approach introduces a node grouping methodology based on system topology.Additionally,we utilize the PBFT consensus algorithm for intergroup leader identity verification,effectively reducing the communication complexity of PBFT in large-scale networks.Furthermore,we enhance the Raft algorithm through cryptographic validation during followers’log replication,which enhances the security of the system.Our proposed consensus process not only identifies the identities of malicious agents but also ensures consensus among normal agents.Through extensive simulations,we demonstrate robust convergence,particularly in scenarios with the relaxed topological requirements.Comparative experiments also validate the algorithm’s lower consensus latency and improved efficiency compared to direct PBFT utilization for identity verification and classical secure consensus control method mean subsequence reduced(MSR)algorithm.
文摘Through three millennia of practice,Traditional Chinese Medicine(TCM)has evolved by integrating knowledge from diverse disciplines,forging a distinct developmental path that respects its ancient foundations while incorporating innovation.TCM has achieved significant breakthroughs in elucidating its theoretical foundations using contemporary scientific methodologies,through the implementation of modernization initiatives over the past three decades.The TCM modernization program has yielded continuous innovations,propelling TCM into a high-quality development stage across both clinical practice and industrial applications.Notably,these advances have enhanced global recognition and adoption of TCM.
文摘AIM To determine the application of clinical practice guidelines for the current management of diverticulitis and colorectal surgeon specialist consensus in Australia and New Zealand.METHODS A survey was distributed to 205 colorectal surgeons in Australia and New Zealand, using 22 hypothetical clinical scenarios.RESULTS The response rate was 102(50%). For 19 guidelinebased scenarios, only 11(58%) reached consensus(defined as > 70% majority opinion) and agreed with guidelines; while 3(16%) reached consensus and did not agree with guidelines. The remaining 5(26%) scenarios showed community equipoise(defined as less than/equal to 70% majority opinion). These included diagnostic imaging where CT scan was contraindicated, management options in the failureof conservative therapy for complicated diverticulitis, surgical management of Hinchey grade 3, proximal extent of resection in sigmoid diverticulitis and use of oral mechanical bowel preparation and antibiotics for an elective colectomy. The consensus areas not agreeing with guidelines were management of simple diverticulitis, management following the failure of conservative therapy in uncomplicated diverticulitis and follow-up after an episode of complicated diverticulitis. Fifty-percent of rural/regional based surgeons would perform an urgent sigmoid colectomy in failed conservative therapy of diverticulitis compared to only 8% of surgeons city-based(Fisher's exact test P = 0.016). In right-sided complicated diverticulitis, a greater number of those in practice for more than ten years would perform an ileocecal resection and ileocolic anastomosis(79% vs 41%, P < 0.0001).CONCLUSION While there are areas of consensus in diverticulitis management, there are areas of community equipoise for future research, potentially in the form of RCTs.
文摘I. The Value Tyranny of the Universality of Western Human Rights Discourse From the perspective of history, human rights discourse originating in the West is first of all a kind of special discourse, rather than universal words. ＂Human rights discourse is a language of rights, which is a language of Western culture. Therefore, in terms of concept, there is no concept of ＇human rights＇ in traditional Confucianism, not even the concept of ＇rights＇. In this sense, the concept ＇human rights＇ is a product of typical Western culture, although it appeared in modern times and it was the out- come of the development of civil society and democracy.TM Marked by unique Western color, human rights discourse originated from the special Western economic, political, histori- cal and cultural background and has its unique consciousness of problems and practical direction. For example,
基金supported by the National Natural Science Foundation of China(No.62322307)the Sichuan Science and Technology Program(No.2023NSFSC1968).
文摘In this paper,a fixed-time optimized control scheme with prescribed performance is presented for bipartite consensus of nonlinear multi-agent systems(MASs).To enforce predefined transient and steady-state performance within a fixed time,a fixed-time prescribed performance function(FTPPF)is introduced.The control design is achieved via an identifier-actor-critic framework that approximates the solution to the Hamilton-Jacobi-Bellman equation.Unknown system dynamics are compensated by fuzzy logic systems,and a rounding quantizer processes the signal of the leader to reduce the communication costs.The proposed method ensures all consensus errors converge with prescribed performance bounds in a fixed time.Simulation results validate the theoretical findings.
基金supported in part by the National Natural Science Foundation of China (62033009)the Creative Activity Plan for Science and Technology Commission of Shanghai (20510712300,21DZ2293500)the Supported by Science Foundation of Donghai Laboratory。
文摘In this paper, the fixed-time event-triggered obstacle avoidance consensus control for a multi-AUV time-varying formation system in a 3D environment is presented by using an improved artificial potential field and leader-follower strategy(IAPF-LF). Firstly, the proposed fixed-time control can achieve the desired multi-AUV formation within a fixed settling time in any initial system state. Secondly, an event-triggered communication strategy is developed to govern the communication among AUVs, and the communication energy consumption can be decremented. The time-varying formation obstacle avoidance control algorithm based on IAPF-LF is designed to avoid static and dynamic obstacles, the desired formation is maintained in the presence of external disturbances, and there is no Zeno behavior under the fixed-time event-triggered consensus control strategy.The stability of the system is proved by the Lyapunov function and inequality scaling. Finally, simulation examples and water pool experiments are reported to verify the performance of the proposed theoretical algorithms.
文摘Blockchain is a distributed public ledger that keeps track of all transactions that have ever taken place in the system. As a distributed ledger, a consensus mechanism is required to ensure all the transaction functions properly. In order to reach a consensus, it is critical to emphasize the importance of performance and efficiency. The use of the right consensus algorithm will significantly improve the efficiency of a blockchain application. This paper reviewed several types of consensus algorithms used in blockchain and discusses the idea of a new consensus algorithm that can improve the performance of consortium blockchain.
基金supported by the National Natural Science Foundation of China(62473316,62073269)the Natural Science Foundation of Chongqing,China(CSTB2022NSCQ-MSX0963)+1 种基金Guangdong Basic and Applied Basic Research Foundation(2023A1515011220)Aeronautical Science Foundation of China(2020Z034053002)。
文摘The article investigates the optimal energy management(OEM)problem for microgrids.To figure out the problem in fixed time and alleviate communication load with limited resources,this article devises a novel fixed-time stability lemma and an event-triggered(ET)fixed-time distributed OEM approach.Using Lyapunov stability theory,the distributed approach has been proven to converge in fixed time and the upper bound on convergence time can be derived without dependence on the initial states.The dynamic ET method is raised to dynamically adjust the triggering threshold and reduce communication redundancy.In addition,Zeno behavior is avoided.Simulations are given to show the effectiveness and advantage of the designed distributed OEM method.
基金supported by the National Key Research and Development Program of China(2020YFA0714300)the National Natural Science Foundation of China(62003084,62203108,62073079)+3 种基金the Natural Science Foundation of Jiangsu Province of China(BK20200355)the General Joint Fund of the Equipment Advance Research Program of Ministry of Education(8091B022114)Jiangsu Province Excellent Postdoctoral Program(2022ZB131)China Postdoctoral Science Foundation(2022M720720,2023T160105).
文摘The accelerated method in solving optimization problems has always been an absorbing topic.Based on the fixedtime(FxT)stability of nonlinear dynamical systems,we provide a unified approach for designing FxT gradient flows(FxTGFs).First,a general class of nonlinear functions in designing FxTGFs is provided.A unified method for designing first-order FxTGFs is shown under Polyak-Łjasiewicz inequality assumption,a weaker condition than strong convexity.When there exist both bounded and vanishing disturbances in the gradient flow,a specific class of nonsmooth robust FxTGFs with disturbance rejection is presented.Under the strict convexity assumption,Newton-based FxTGFs is given and further extended to solve time-varying optimization.Besides,the proposed FxTGFs are further used for solving equation-constrained optimization.Moreover,an FxT proximal gradient flow with a wide range of parameters is provided for solving nonsmooth composite optimization.To show the effectiveness of various FxTGFs,the static regret analyses for several typical FxTGFs are also provided in detail.Finally,the proposed FxTGFs are applied to solve two network problems,i.e.,the network consensus problem and solving a system linear equations,respectively,from the perspective of optimization.Particularly,by choosing component-wisely sign-preserving functions,these problems can be solved in a distributed way,which extends the existing results.The accelerated convergence and robustness of the proposed FxTGFs are validated in several numerical examples stemming from practical applications.
文摘The PBFT (Practical Byzantine Fault Tolerance, PBFT) consensus algorithm, which addressed the issue of malicious nodes sending error messages to disrupt the system operation in distributed systems, was challenging to support massive network nodes, the common participation over all nodes in the consensus mechanism would lead to increased communication complexity, and the arbitrary selection of master nodes would also lead to inefficient consensus. This paper offered a PBFT consensus method (Role Division-based Practical Byzantine Fault Tolerance, RD-PBFT) to address the above problems based on node role division. First, the nodes in the system voted with each other to divide the high reputation group and low reputation group, and determined the starting reputation value of the nodes. Then, the mobile node in the group was divided into roles according to the high reputation value, and a total of three roles were divided into consensus node, backup node, and supervisory node to reduce the number of nodes involved in the consensus process and reduced the complexity of communication. In addition, an adaptive method was used to select the master nodes in the consensus process, and an integer value was introduced to ensure the unpredictability and equality of the master node selection. Experimentally, it was verified that the algorithm has lower communication complexity and better decentralization characteristics compared with the PBFT consensus algorithm, which improved the efficiency of consensus.
基金funded by Universiti Teknologi PETRONAS and grants(YUTP-PRG:015PBC-011).
文摘This study conducts a systematic literature review(SLR)of blockchain consensus mechanisms,an essential protocols that maintain the integrity,reliability,and decentralization of distributed ledger networks.The aim is to comprehensively investigate prominent mechanisms’security features and vulnerabilities,emphasizing their security considerations,applications,challenges,and future directions.The existing literature offers valuable insights into various consensus mechanisms’strengths,limitations,and security vulnerabilities and their real-world applications.However,there remains a gap in synthesizing and analyzing this knowledge systematically.Addressing this gap would facilitate a structured approach to understanding consensus mechanisms’security and vulnerabilities comprehensively.The study adheres to Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)guidelines and computer science standards and reviewed 3749 research papers from 2016 to 2024,excluding grey literature,resulting in 290 articles for descriptive analysis.The research highlights an increased focus on blockchain consensus security,energy efficiency,and hybrid mechanisms within 60%of research papers post-2019,identifying gaps in scalability,privacy,and interoperability for future exploration.By synthesizing the existing research and identifying the key trends,this SLR contributes to advancing the understanding of blockchain consensus mechanisms’security and guiding future research and structured innovation in blockchain systems and applications.
基金supported by the National Natural Science Foundation of China under Grant Nos.62003066 and 62163008the Natural Science Foundation of Chongqing Municipality under Grant No.cstc2021jcyjmsxmX0331。
文摘This paper addresses the problem of achieving practical consensus in large-scale agent clusters governed by nonlinear reaction-diffusion equations,while considering actuator saturation and external disturbances.Different with the traditional consensus methods,the proposed observer-based boundary control relies on non-collocated and incomplete local measurements rather than idealistic global spatiotemporal dynamics.First,the discrete agents with a chain topology are regarded as a continuum,resulting in the derivation of a reaction-diffusion equation to replace the cumbersome ordinary differential equations(ODEs).Subsequently,an observer is constructed based on the non-collocated measurements to estimate the errors between the leader-following agent clusters.Then,a sufficient condition for the consensus controller is derived by improving the Lyapunov direct method,mean value theorem of integrals and a variation of Wirtinger's inequality.Furthermore,an optimization problem is proposed to effectively enhance the H_(∞)disturbance attenuation performance in the presence of actuator saturation.Finally,the comparison simulation is given to illustrate the superiority of proposed methodology.
