Dynamic Event-Triggered Consensus Control for Input Constrained Multi-Agent Systems With a Designable Minimum Inter-Event Time

This paper investigates the consensus control of multi-agent systems(MASs) with constrained input using the dynamic event-triggered mechanism(ETM).Consider the MASs with small-scale networks where a centralized dynamic ETM with global information of the MASs is first designed.Then,a distributed dynamic ETM which only uses local information is developed for the MASs with large-scale networks.It is shown that the semi-global consensus of the MASs can be achieved by the designed bounded control protocol where the Zeno phenomenon is eliminated by a designable minimum inter-event time.In addition,it is easier to find a trade-off between the convergence rate and the minimum inter-event time by an adjustable parameter.Furthermore,the results are extended to regional consensus of the MASs with the bounded control protocol.Numerical simulations show the effectiveness of the proposed approach.

Minimum Dwell Time for Global Exponential Stability of a Class of Switched Positive Nonlinear Systems

This paper will investigate global exponential stability analysis for a class of switched positive nonlinear systems under minimum dwell time switching, whose nonlinear functions for each subsystem are constrained in a sector field by two odd symmetric piecewise linear functions and whose system matrices for each subsystem are Metzler. A class of multiple time-varying Lyapunov functions is constructed to obtain the computable sufficient conditions on the stability of such switched nonlinear systems within the framework of minimum dwell time switching.All present conditions can be solved by linear/nonlinear programming techniques. An example is provided to demonstrate the effectiveness of the proposed result.

Determination of the Minimum Testing Time for Wireline Formation Testing with the Finite Element Method

The wireline formation tester （WFT） is an important tool for formation evaluation, such as calculating the formation pressure and permeability, identifying the fluid type, and determining the interface between oil and water. However, in a low porosity and low permeability formation, the supercharge pressure effect exists, since the mudcake has a poor sealing ability. The mudcake cannot isolate the hydrostatic pressure of the formation around the borehole and the mud seeps into the formations, leading to inaccurate formation pressure measurement. At the same time, the tool can be easily stuck in the low porosity/low permeability formation due to the long waiting and testing time. We present a method for determining the minimum testing time for the wireline formation tester. The pressure distribution of the mudcake and the formation were respectively calculated with the finite element method （FEM）. The radius of the influence of mud pressure was also computed, and the minimum testing time in low porosity/low permeability formations was determined within a range of values for different formation permeabilities. The determination of the minimum testing time ensures an accurate formation pressure measurement and minimizes possible accidents due to long waiting and testing time.

Cognitive MAC Protocol with Minimum Sampling Time and Cross-Layer Cooperation for Low Signal-to-Noise Ratio Environments

The previous Decentralised Cognitive Medium Access Control(DC-MAC) protocol allows Secondary Users(SUs) to independently search for spectrum access opportunities without the need for a central coordinator.DC-MAC assumes that the detection scheme is ideal at the Physical(PHY) layer.In fact,a more complex detection algorithm is impractical in distributed spectrum sharing scenarios.Energy Detection(ED) at the PHY layer has become the most common method because of its low computational and implementation complexities.Thus,it is essential to integrate the DC-MAC with ED at the PHY layer.However,ED requires the Minimum Sampling Time(MST)duration to achieve the target detection probability in low Signal-to-Noise Ratio(SNR)environments.Otherwise,it cannot achieve the expected detection performance.In this paper,we derive an accurate expression of MST for ED in low SNR environments.Then,we propose an Optimised DC-MAC(ODC-MAC) protocol which is based on MST,and which amends the aforementioned problems of DC-MAC with ED.Moreover,the closed-form expressions for the unreliable data transmission probability are derived for both DC-MAC and ODC-MAC.We show that the simulation results agree well with the theoretical analyses.The proposed ODC-MAC can improve the data transmission reliability and enhance the throughput compared to the performance of the traditional DC-MAC.

KINEMATIC MINIMUM-TIME TRAJECTORY PLANNING FOR A MANIPULATOR

By using a phase-plane analysis method,the minimum-time trajectory plan-ning problem of a manipulator moving along a given geometric path subject to the con-straints of joint velocities and accelerations is solved in this paper.The simulation resultfor the first three joints of PUMA-560 is given.

Numerical Minimum Time Control to a Class of Singular Integro-Differential Equations

This study presents a numerical method for determining the minimum time required for the states of one class of integro-differential equations of the first kind to reach its attainable region by assuming the forcing terms of the equations as controls. These equations consist of integro-differential parts containing weakly singular kernels. The feasibility of the numerical method is demonstrated by comparing the minimum time and corresponding possible time by using extreme controls to reach the attainable region under different initial conditions.

融合均值榜样的反向互学习水母搜索算法

为解决水母搜索算法(jellyfish search algorithm,JS)的洋流运动缺乏多样性、群内运动缺乏引导性、种群间信息无交流,造成搜索速度慢、稳定性差及易早熟的问题,构建了一种融合均值榜样的反向互学习水母搜索算法(oppositional-mutual learning jellyfish search algorithm based on mean-value example,OMLJS).首先在水母跟随洋流运动(全局搜索)部分,利用前两代水母的平均位置代替只考虑上一代水母的平均位置来引导水母个体的位置更新,提高算法的全局搜索能力;其次在水母的群内主动运动(局部搜索)部分,利用最优个体代替随机个体来引导水母进行更有效的搜索,加快算法的收敛速度;然后在水母进入下一次迭代前增加对水母种群进行动态反向互学习步骤,增加种群多样性及增强种群间的信息交流,达到互补另外两个策略,提高算法的整体优化性能.选用12个经典的基准测试优化函数,将OMLJS与5个对比算法从解的平均值、最优值及方差进行对比分析,并用于求解最小生成树问题,OMLJS能够更快地找到最小生成树.实验结果表明,OMLJS的收敛速度、求解精度明显提高.

基于最小剩余时间算法与SR-IOV技术的GPU资源优化调度方案

为了优化GPU资源利用率,文章提出了一种新型的GPU资源调度方案。该方案结合了最小剩余时间算法与SR-IOV(SingleRootI/OVirtualization)技术,可优化多用户、多任务环境下的GPU资源利用率和系统性能。传统的GPU调度方法往往面临资源利用不足、任务等待时间长和系统吞吐量受限等问题。为了应对这些挑战,该方案通过动态分析任务的剩余执行时间,利用SR-IOV技术实现了GPU资源的细粒度隔离与共享,可为更高效的资源分配和任务调度提供支持。实验结果表明,相较于传统的无调度、容器调度和常见机器学习调度方案,该方案在均值准确率、GPU利用率、系统吞吐量和任务执行时间等方面均具有一定的优势,可为多用户多任务场景下的GPU资源管理提供有益的参考。

硬岩引水隧洞掘进爆破参数研究

为探究不同岩性时引水隧洞爆破合理的延迟时间和最小抵抗线,以瓯江引水工程三标段隧洞爆破工程为背景,依据理论公式分析了隧洞爆破的合理延时;通过ANSYS数值模拟软件建立不同最小抵抗线的计算模型,对不同工况下岩体内有效应力、裂纹扩展情况进行对比分析。结果表明,对于花岗岩和凝灰岩,随着最小抵抗线增大,对应的延时也增大,有效应力作用呈衰减态势,裂纹扩展逐渐分散;根据优化结果以3m的炮孔深度为例,花岗岩和凝灰岩下掏槽孔与辅助孔、崩落孔间、崩落孔与周边孔的延时分别取80ms,50ms,30ms和90ms,50ms,40ms,最小抵抗线为600mm~650mm,经现场试验表明爆落岩石块度均匀、易于装运,断面轮廓成型规整,炮孔利用率达到91%,光爆效果良好、与研究结果吻合。

面向地铁施工环境的残差加权定位算法

在地铁施工环境中,进行地下室内定位,非视距误差是影响位置估计稳定性与准确性的一个重要因素。目前已经出现一些技术可以消除一定的非视距误差,但往往都需要关于非视距信道条件的先验信息。提出一种改进的残差加权位置估计算法(Developed residual weighting algorithm,D-rwgh),该算法基于最小残差原则,通过前一轮的计算不断剔除产生误差最大的基站,然后将不同基站数对应的位置估计进行残差加权,加权结果即为最终的定位结果。实验结果表明,该算法无需信道的先验信息,且在非视距传播环境下具有较好的定位精度。

南沙海域搜救可达性评估

南沙群岛周边海域作为世界上最繁忙的海域之一,是海难事故的频发区,快速的海上搜救是保障人民生命财产安全的重要措施,因此,研究南沙海域的搜救可达性就显得尤为重要。文章基于乘法加权Voronoi图对南沙群岛27个岛礁的影响范围进行了划分,利用船速校正模型得到波浪场影响下船舶航行的实际速度,然后通过最短路径算法计算得到南沙海域周边5国共20个港口至该区域的加权平均可达时间,并使用多种评价指标对各国的可达性能力进行评估分析。结果显示:1)马来西亚至南沙海域的综合可达性最优,平均可达时间最短,其次是文莱、菲律宾和越南,平均可达时间均在20 h以内。而中国至该海域的可达性较差,排名最后。2)新增永暑礁港口后,中国的可达性得到显著提高,平均可达时间缩短至15.54 h,24 h覆盖范围增加了约92.0%。3)鉴于距离南沙海域较远,中国应该加强在远海岛礁建设中转基地及配套搜救设施的能力,这一举措将显著提高中国至中、远海区域的可达性。

基于贪心算法的板式家具订单备料调度研究

针对板式家具订单备料调度过程中的调度混乱、设备使用效率低的问题,本文通过对板式家具备料进行现场调研,结合订单开料工艺特点,以最小完工时间为目标,构建数学模型,将贪心算法应用在板式家具订单的调度备料中。在此基础上,依据模型进行算法设计,并对算法进行仿真试验,通过对采集的数据进行分析,验证了算法的可行性,提高了家具的备料效率。与工厂现有的调度方式相比,采用本文的调度方案可节约时间700 s,生产效率提高18.89%,对于解决多机并行的订单备料调度具有指导意义。

基于哈里斯鹰优化算法的引信装定系统参数优化方法

为了满足坦克炮弹药作战实时性的需求,开展引信快速准确接收武器平台传输的敌方距离、方位等信息的研究,对提高作战毁伤效能十分重要。针对引信在武器平台实际环境约束下能量和信息无法快速可靠接收的问题,建立引信共击发通道装定系统能量信息同步传输的数学模型,形成目标函数为通过优化系统设计参数使装定时间最小、约束条件为平台恶劣信道环境下能量信息可靠接收的优化模型,采用哈里斯鹰优化(Harris Hawk Optimization,HHO)算法求解装定系统设计参数的最优值。仿真结果表明,基于HHO算法的系统参数优化方法可以得到最优的系统设计参数,与参数未优化的系统对比,不同信道参数下,能量信息同步传输的时间平均减少了26.4%,信息的可靠接收比平均提高了40.4%,特别是在信道电容大于5 nF的恶劣信道环境下仍能保证信息可靠接收,能量信息接收的快速性和可靠性都大幅提高,作战效能得到优化,通过实验室实验验证该方法的有效性。

网联环境下的交叉口信号配时与车辆轨迹联合优化方法

文中提出一种综合考虑交叉口信号配时和车辆轨迹的联合优化法.以车辆的原始轨迹为基础,以交叉口车辆通行时间最小化为信号控制优化目标,建立信号配时优化模型来计算最优的信号周期序列和相位时间,并根据相位时间划分车辆运动轨迹为到达交叉口停车线前的加速、匀速阶段,以及驶过交叉口停车线的加速、匀速阶段,在每个阶段获取最佳的车头时距和期望速度,优化车辆的原始轨迹.基于新的轨迹再次进行信号配时优化.以交通需求量、左转比率和信号周期时长作为考虑因素,进行SUMO仿真实验将所提出的联合优化法与实时信号控制方法进行比较.结果表明:联合优化法在不同的平衡交通需求量下能够提高交叉口通行能力30.5%;在随机交通需求量下能提高交叉口通行效率17.3%;而在不同的左转比率和信号周期时长情况下能提高通行效率66.6%和21.7%,验证了提出的联合优化方法提高线交叉口通行效率的有效性.

基于VisVAP的长距离单车道双向通行区间的感应协调控制研究

山岭地区地形复杂,施工条件恶劣,为保证施工期间各类工程材料的运输和工程建设的需要,需要在施工区域内修筑长距离施工便道满足客、货运输的需要。囿于地形条件限制,实际工程中施工便道一般只能修筑为单车道,但是需要承担双向通行的行车需求。为了提高长距离单车道双向通行区间的通行效率和行车安全性,本文结合列车运行自动闭塞控制原理,提出了一种基于VisVAP的长距离单车道双向通行区间的多区间感应协调控制方案。将感应线圈分为进入区间需求响应线圈(Knock型)、区间占用响应线圈(Occupy型)和通过区间响应线圈(Pass型),提出了用于中间控制区间的正常四相位控制方案以及用于端口控制区间的设置最小红灯时间Δt的特殊三相位控制方案;并给出了端口、中间控制区间的VisVAP控制流程文件,提出了最小红灯时间Δt限值的计算方法并通过仿真证明了其合理可行性。最后以川藏铁路大渡河桥工程施工便道中一段长L=2000 m的单道双向通行区间为研究对象进行Vissim仿真,研究发现,当上行Δt设置为80 s,下行Δt设置为60 s时,控制区间能保证行车延误最小,车流运行流畅度较高,提升了通行效率,保障了通行安全。

山东地震台网监测预警能力评估分析

国家地震烈度速报与预警项目已进入试运行阶段,山东全省作为重点预警区,其预警能力直接关系山东及其周边地区的预警效能。为精确评估山东地震台网的监测预警能力,以本台网所记录到的波形数据为基础,将仪器最大概率峰值位移作为背景噪声评估指标获得山东地震台网的监测能力。在此基础上,考虑到预警时效性需求,系统评估了山东地震台网中,由125台速度计组成的测震台网、由152台加速度计组成的强震台网、由1198台烈度仪组成的烈度台网及其融合网的预警最小震级和首报时间。结果表明,山东地震台网平均监测能力达到M_(L)0.4,最小值可达M_(L)-0.2,最大值可达M_(L)1.1;测震、强震和烈度台网“三网”融合后预警最小震级、首台触发后和震后的预警时间平均值分别约为M_(L)2.2、3s和5s,“三网”融合进行预警的策略可以满足地震预警“稳、准、快”的要求。

基于非值乘时间成本的乘务排班计划优化编制方法研究

乘务排班计划是城市轨道交通运输计划的重要组成部分,其编制方案优劣直接影响企业运营安全与乘务支出。在班制规定工作时间内,非值乘时间占比越高,工作所需人力资源越多,运营支出效益越低。文章通过缩减乘务人员非值乘时间中的非必要整备时间,从时间成本角度出发,构建最小费用模型。同时设计以爬山算法作为局部搜索策略的文化基因算法,用于优化传统遗传算法对于解的早熟或不收敛导致局部最优的潜在可能。最后以上海市轨道交通某条线路作为案例研究,结果表明模型能够在满足运营需求的前提下,优化乘务人员数量,从而降低乘务支出。其研究结果可为城市轨道交通精细化管理提供理论依据和参考。

ITD结合参数优化MOMEDA的滚动轴承故障特征提取

针对固有时间尺度分解(Intrinsic time scale decomposition,ITD)方法在强背景噪声影响下难以提取轴承故障特征的问题,提出了一种ITD与参数优化的多点最优最小熵解卷积(Multipoint optimal minimum entropy deconvolution adjusted,MOMEDA)相结合的滚动轴承故障特征提取方法。首先根据包络谱峰值因子最大原则提取包含丰富故障信息的ITD分量,其次对该分量进行MOMEDA降噪处理。对影响MOMEDA滤波效果的两个参数——故障周期T与滤波器长度L分别以多点峭度和平方包络谱的基尼指数进行优化,最后进行包络谱分析提取故障特征频率。通过仿真信号与实测信号分析表明该方法能在强噪声干扰下有效提取故障特征。

A Different Brachistochrone Problem with Counterintuitive Results

A problem similar to the famous brachistochrone problem is examined in which, instead of a smooth curve, the path consists of two straight-line sections, one slant and one horizontal. The condition for minimum sliding time is investigated, producing results that are both counterintuitive and interesting.

基于平均声速测量的声速剖面实时重构方法

针对传统的声速剖面重构方法往往不具备实时性的问题,本文提出了一种基于平均声速测量的声速剖面实时重构方法。首先,基于历史数据进行特征分解并选择经验正交函数(Empirical Orthogonal Function, EOF)的阶次;其次,利用实测的水下某深度的声速和该深度至海面的平均声速,通过求二元一次方程组的最小范数解得到EOF重构系数;最后,结合历史声速剖面重构全海深声速剖面。使用西太平洋海域的再分析数据对该方法进行了仿真验证,结果表明:采用该方法重构的声速剖面与真实声速剖面拟合效果较好,平均均方根误差约为1.31 m·s-1。本文所提方法可为水下航行器实时重构声速剖面提供技术支撑。