Event-triggered non-fragile H∞ fault detection for discrete time-delayed nonlinear systems with channel fadings

In this paper, the event-triggered non-fragile H_∞ fault detection filter is designed for a class of discrete-time nonlinear systems subject to time-varying delays and channel fadings. The Lth Rice fading model is utilized to reflect the actual received measurement signals, and its channel coefficients own arbitrary probability density functions on interval [0,1]. The event-based filter is constructed to reduce unnecessary data transmissions in the communication channel, which only updates the measurement signal to the filter when the prespecified “event” is triggered. Multiplicative gain variations are utilized to describe the phenomenon of parameter variations in actual implementation of the filter. Based on Lyapunov stability theory, stochastic analysis technology along with linear matrix inequalities (LMIs) skills, sufficient conditions for the existence of the non-fragile fault detection filter are obtained which make the filtering error system stochastically stable and satisfy the H_∞ constraint. The gains of the filter can be calculated out by solving the feasible solution to a certain LMI. A simulation example is given to show the effectiveness of the proposed method.     

Finite-time and fixed-time synchronization of discontinuous complex networks: A unified control framework design

This paper is concerned with the finite-time and fixed-time synchronization of complex networks with discontinuous nodes dynamics. Firstly, under the framework of Filippov solution, a new theorem of finite-time and fixed-time stability is established for nonlinear systems with discontinuous right-hand sides by using mainly reduction to absurdity. Furthermore, for a class of discontinuous complex networks, a general control law is firstly designed. Under the unified control framework and the same conditions, the considered networks are ensured to achieve finite-time or fixed-time synchronization by only adjusting the value of a key control parameter. Based on the similar discussion, a unified control strategy is also provided to realize respectively asymptotical, exponential and finite-time synchronization of the addressed networks. Finally, the derived theoretical results are supported by an example with numerical simulations.     

Adaptive finite-time consensus of a class of disturbed multi-agent systems

In this paper, the finite-time exponential consensus problem is addressed for a class of multi-agent systems against some disturbed factors, which include system uncertainties, communication perturbations, and actuator faults. All disturbed factors are supposed to be influenced by internal and external effects of systems. The internal effects are described in terms of dependency on the system states, while the external actions are restricted by constant bounds. To obtain the information of the rate of dependency on the states and constant bounds, an adaptive mechanism is designed to estimate the rate and bounds. Based on these estimates, a distributed adaptive sliding mode controller is constructed to eliminate the effects of those disturbed factors. Then exponential consensus of the closed-loop adaptive multi-agent system is achieved within a finite time based on Lyapunov stability theory. The efficiency of the developed adaptive consensus control strategy is verified by a coupled system with four F-18 aircrafts of decoupled longitudinal model.     

Nonlinear optimal control with disturbance rejection for asteroid landing

This paper presents an optimal solution to asteroid soft landing problem, on the base of $\theta ?D$ control technique and disturbance rejection mechanism. The control objective is to drive a probe to reach the surface of an asteroid with a desirable line-of-sight angle and zero velocity, eliminating the influence of external disturbance. Firstly, elementary $\theta ?D$ technique is applied in the absence of disturbance to tackle the nonlinear optimal control problem. Secondly, the disturbance is estimated in the fast-estimation framework with explicitly bounded estimation error. Afterwards, an integrated control protocol is presented in a feed-forward structure by the aid of an additional variable-structure term to ensure stability under time-varying disturbance. Simulation results of the proposed approach compared with the results of elementary $\theta ?D$ method and robust $\theta ?D$ method are presented at the end of this paper, demonstrating the effectiveness of the proposed control protocol.     

Reliability and Validity of Finger Strength and Endurance Measurements in Rock Climbing

Purpose: An advanced system for the assessment of climbing-specific performance was developed and used to: (a) investigate the effect of arm fixation (AF) on construct validity evidence and reliability of climbing-specific finger-strength measurement; (b) assess reliability of finger-strength and endurance measurements; and (c) evaluate the relationship between finger flexor all-out test scores and climbing ability. Methods: To determine the effect of AF, 22 male climbers performed 2 maximal strength and all-out tests with AF (shoulder and elbow flexed at 90°) and without AF (shoulder flexed at 180° and elbow fully extended). To determine reliability, 9 male climbers completed 2 maximal strength tests with and without AF and an all-out and intermittent test without AF. Results: The maximal strength test without AF more strongly determined climbing ability than the test with AF (r² = .48 and r² = .42 for sport climbing; r² = .66 and r² = .42 for bouldering, respectively). Force and time variables were highly reliable; the rate of force development and fatigue index had moderate and low reliability. The maximal strength test with AF provided slightly higher reliability than without AF (intraclass correlation coefficient [ICC] = 0.94, ICC = 0.88, respectively). However, smaller maximal forces were achieved during AF (484 ± 112 N) than without AF (546 ± 132 N). All-out test average force had sufficiently high reliability (ICC = 0.92) and a relationship to sport climbing (r² = .42) and bouldering ability (r² = .58). Conclusion: Finger strength and endurance measurements provided sufficient construct validity evidence and high reliability for time and force parameters. Arm fixation provides more reliable results; however, the position without AF is recommended as it is more related to climbing ability.     

大数据背景下政府管理研究热点分析

【目的/意义】大数据为政府管理带来新的挑战与机遇。对于大数据背景下政府管理相关研究成果的梳理, 可进一步明晰该领域研究现状,从而为未来研究确定方向。【方法/过程】以CNKI的期刊库为数据来源,利用Bibex? cel、Ucinet和SPSS软件对关键词进行分析,进而发现大数据背景下政府管理研究的热点。【结果/结论】通过分析发 现大数据背景下政府管理研究热点主要集中于信息技术、电子政务、智慧城市、信息安全四个方面。同时非结构化 数据、数据开放、数据挖掘、数据管理、数据平台等方面有望成为后续研究的重点。     

第11届全运会女子举重冠军抓举技术的运动学参数特征研究

采用国产星高钛运动录像采集和解析软件(3D-SignalTEC),对第11届全国运动会女子举重4个级别冠军的抓举技术进行数字录像解析,进一步研究运动员在抓举过程中膝关节角度、髋关节角度、躯干角度和杠铃中心点垂直速度随时间变化曲线的关系,更深层次地揭示我国优秀女子举重运动员的抓举技术特征.     

论新《保险法》免责条款说明义务的完善

由于保险交易消费化特征突出,保险人与投保人之间交易能力相差甚远,投保人对保险条款的理解主要依赖保险人提供的说明,加之保险人利用保险条款进行推诿欺诈的客观事实已经造成了公众对保险事业的信任危机。在此情形下,保险人免责条款说明义务的完善,可以使处于弱势地位的投保人在缔结保险合同时降低信息收集和注意的风险,相应地提高保险人订约信息的收集与交流注意义务。所以完善保险人免责条款说明义务成为一种必然选择。     

基于图书借阅的人类行为标度律分析

通过研究两所大学图书馆数据库中的真实资料,从群体和个体两个层面分析一次借阅过程中图书的借阅时间和用户连续两次借阅或还回图书的时间间隔等统计特征。结果表明,群体行为与个体行为表现出不同的统计特征,除群体行为的借阅时间表现为指数分布外,其它统计量都服从指数范围为1至3的幂律分布。研究说明,人类行为在群体和个体层面上具有不同的多重标度特性。     

P2P数字图书馆虚拟联盟著作权侵权风险分析

基于P2P技术的数字图书馆虚拟联盟的诞生,克服了数字图书馆实体联盟之间缺乏灵活的、有效的动态整合机制的难题。由于虚拟联盟没有中心节点和管理机构,作品的传播难以控制,著作权侵权责任更难以划分。在虚拟联盟中,作为实体机构的数字图书馆主要扮演着者ICP和ISP两种角色,其侵权的方式和责任的认定各不相同。