Consensus of high-order dynamic multi-agent systems with switching topology and time-varying delays

This paper studies the consensus problems for a group of agents with switching topology and time-varying communication delays, where the dynamics of agents is modeled as a high-order integrator. A linear distributed consensus protocol is proposed, which only depends on the agent＇s own information and its neighbors＇ partial information. By introducing a decomposition of the state vector and performing a state space transformation, the closed-loop dynamics of the multi-agent system is converted into two decoupled subsystems. Based on the decoupled subsystems, some sufficient conditions for the convergence to consensus are established, which provide the upper bounds on the admissible communication delays. Also, the explicit expression of the consensus state is derived. Moreover, the results on the consensus seeking of the group of high-order agents have been extended to a network of agents with dynamics modeled as a completely controllable linear time-invariant system. It is proved that the convergence to consensus of this network is equivalent to that of the group of high-order agents. Finally, some numerical examples are given to demonstrate the effectiveness of the main results.

Topological approach of liver segmentation based on 3D visualization technology in surgical planning for split liver transplantation

BACKGROUND Split liver transplantation(SLT)is a complex procedure.The left-lateral and right tri-segment splits are the most common surgical approaches and are based on the Couinaud liver segmentation theory.Notably,the liver surface following right trisegment splits may exhibit different degrees of ischemic changes related to the destruction of the local portal vein blood flow topology.There is currently no consensus on preoperative evaluation and predictive strategy for hepatic segmental necrosis after SLT.AIM To investigate the application of the topological approach in liver segmentation based on 3D visualization technology in the surgical planning of SLT.METHODS Clinical data of 10 recipients and 5 donors who underwent SLT at Shenzhen Third People’s Hospital from January 2020 to January 2021 were retrospectively analyzed.Before surgery,all the donors were subjected to 3D modeling and evaluation.Based on the 3D-reconstructed models,the liver splitting procedure was simulated using the liver segmentation system described by Couinaud and a blood flow topology liver segmentation(BFTLS)method.In addition,the volume of the liver was also quantified.Statistical indexes mainly included the hepatic vasculature and expected volume of split grafts evaluated by 3D models,the actual liver volume,and the ischemia state of the hepatic segments during the actual surgery.RESULTS Among the 5 cases of split liver surgery,the liver was split into a left-lateral segment and right trisegment in 4 cases,while 1 case was split using the left and right half liver splitting.All operations were successfully implemented according to the preoperative plan.According to Couinaud liver segmentation system and BFTLS methods,the volume of the left lateral segment was 359.00±101.57 mL and 367.75±99.73 mL,respectively,while that measured during the actual surgery was 397.50±37.97 mL.The volume of segment IV(the portion of ischemic liver lobes)allocated to the right tri-segment was 136.31±86.10 mL,as determined using the topological approach to liver segmentation.However,during the actual surgical intervention,ischemia of the right tri-segment section was observed in 4 cases,including 1 case of necrosis and bile leakage,with an ischemic liver volume of 238.7 mL.CONCLUSION 3D visualization technology can guide the preoperative planning of SLT and improve accuracy during the intervention.The simulated operation based on 3D visualization of blood flow topology may be useful to predict the degree of ischemia in the liver segment and provide a reference for determining whether the ischemic liver tissue should be removed during the surgery.

Cognitive Navigation for Intelligent Mobile Robots:A Learning-Based Approach With Topological Memory Configuration

Autonomous navigation for intelligent mobile robots has gained significant attention,with a focus on enabling robots to generate reliable policies based on maintenance of spatial memory.In this paper,we propose a learning-based visual navigation pipeline that uses topological maps as memory configurations.We introduce a unique online topology construction approach that fuses odometry pose estimation and perceptual similarity estimation.This tackles the issues of topological node redundancy and incorrect edge connections,which stem from the distribution gap between the spatial and perceptual domains.Furthermore,we propose a differentiable graph extraction structure,the topology multi-factor transformer(TMFT).This structure utilizes graph neural networks to integrate global memory and incorporates a multi-factor attention mechanism to underscore elements closely related to relevant target cues for policy generation.Results from photorealistic simulations on image-goal navigation tasks highlight the superior navigation performance of our proposed pipeline compared to existing memory structures.Comprehensive validation through behavior visualization,interpretability tests,and real-world deployment further underscore the adapt-ability and efficacy of our method.

Tracking problem under a time-varying topology

This paper studies the multi-agent tracking problem of a third-order maneuvering target under uncertain communication environments. Each tracking agent is assumed to be a third-order system and can only use its own and neighbors＇ position, velocity, and acceleration information to design its control input. In this work, the uncertain communication environments are modelled by a finite number of constant Laplacian matrices together with their corresponding scheduling functions. Sufficient conditions for the existence of a tracking strategy have been expressed in terms of the solvability of linear matrix inequalities. Finally, a numerical example is employed to demonstrate the effectiveness of the proposed tracking strategy.

Research on Visualization of Long-staple Cotton Growth in Southern Xinjiang

Base on the related researches at home and abroad, using systematic analysis principle mathematical modeling techniques, analysis model of organ collection properties, root structure model, mechanism model of spatial form of organs and dynamic model of plant topological structure in line with the growth of long-staple cotton are constructed, and three-dimensional dynamic simulation of long-staple cotton in southern Xinjiang is finally achieved. The system can promote people＇s understanding and perception on growth process of long-staple cotton in southern Xinjiang, which provides support for analysis of relationship between structure and function of long-staple cotton, design of ideal plant and regulation of growth model.

Topology and Vortex Structures of Turbine Cascade with Different Tip Clearances

This paper uses the topology theory to analyze the surface flowspectrums of straight, positively curved and negatively curvedcascades with relative tip clearances of 0.023 and 0.036, findsapparent differences of topology and vortex structures in the bladetip and the suction side wall corner of single type of cascade withthis two clearances, and studies the mechanism of the differenceformation as well as their effects o the energy loss.

Multi-agent consensus with time-varying delays and switching topologies

The consensus problems of multi-agents with time-varying delays and switching topologies are studied. First, assume that an agent receives state information from its neighbors with fixed communication delays and processes its own state information with time-varying self-delay respectively. The state time-delay feedback is introduced into the existing consensus protocol to begenerate an improved protocol. Then a sufficient condition is derived which can make the system with time-varying self-delays achieve the consensus. On this basis, a specific form of consensus equilibrium influenced by the initial states of agents, time-delays and state feedback intensity is figured out. In addition, the multi-agent consensus is considered with time-varying topologies. Finally, simulations are presented to il ustrate the validity of theoretical results.

Time-varying formation for general linear multi-agent systems via distributed event-triggered control under switching topologies

This paper investigates the time-varying formation problem for general linear multi-agent systems using distributed event-triggered control strategy.Different from the previous works,to achieve the desired time-varying formation,a distributed control scheme is designed in an event-triggered way,in which for each agent the controller is triggered only at its own event times.The interaction topology among agents is assumed to be switching.The common Lyapunov function as well as Riccati inequality is applied to solve the time-varying formation problem.Moreover,the Zeno behavior of triggering time sequences can be excluded for each agent.Finally,a simulation example is presented to illustrate the effectiveness of the theoretical results.

矿山三维巷道参数化建模方法研究与应用

矿山巷道三维可视化作为数字矿山的一个重要组成部分,是开展相关应用研究的基础。针对当前巷道三维建模人工干预高、过度依赖建模软件等问题,提出了矿山三维巷道参数化建模方法。对于部分巷道转折处、分叉口处缺少导线点的情况,通过巷道数据处理,基于搜索算法进行虚拟导线点的补充插值,构建了巷道空间拓扑网络模型。针对巷道空间拓扑网络模型,根据任意2条相交巷道沿角平分线对称的特点,采用基于角平分线对称的建模法,解决了巷道相交处、分叉口处的连通性问题和平滑拼接问题;通过集成方法实现了不同形态断面巷道的集成建模,从而实现了矿山三维巷道网络模型的自动化构建。以典型矿井的实测数据为例开展了应用研究,结果表明:巷道空间拓扑网络模型各个导线点处拓扑连接关系正确,矿山三维巷道模型在巷道相交处、分叉口处连通性和平滑拼接良好,该模型能够直观地展示巷道真实形态和巷道之间的空间关系,为矿山管理者和生产者提供重要的数据信息,方便进行辅助决策,对于矿山安全生产及智慧化管理具有较好的参考意义。

地下管网三维模型的自动化构建与可视化

随着地下市政基础设施普查的全面开展,涌现出标准各异的海量地下管线普查数据。为提高管线普查数据的处理效率与利用率,基于国产化GIS平台,以浙江省地下市政基础设施数据库规范为例,提出一种地下管网三维模型的自动化构建与可视化方法。该方法在数据规范性检查与自动修正的基础上,完成三维拓扑构网;然后制定符号化规范,实现了三维管网的自动符号化。实现了从符合特定规范的管线测绘数据到模型化三维拓扑管网的全自动化处理,为大批量的规范化管线测绘数据的高效处理提供了一个解决方案。

城市轨道交通数据采集与监控系统拓扑着色与二次逻辑可视化方法研究

本文提出一种基于图元重叠面积计算关联性的拓扑着色和二次逻辑可视化方法,用于改进电力监控系统的可视化展示和故障诊断功能。该方法首先计算图元矩形框的面积和相交面积,然后确定图元之间的连接状态,并将关联图元的属性参数设置为其关联的图元ID,最后在组态画面上以不同颜色显示关联状态。将该方法应用于数据采集与监控(SCADA)系统中,能够准确、实时地实现画面中电流的更新,具备较好的可视化效果和高维护性。

网络拓扑可视化系统研究

网络拓扑可视化在计算机网络领域中具有重要的价值,它不仅帮助人们更直观地了解网络结构和连接关系,还能够发现网络中的问题并进行优化。本文设计并实现了网络拓扑可视化系统,该系统主要包括UI层、业务层以及数据层,同时采用力导向的布局算法计算各网络节点的布局。采用本文设计的力导向布局优化算法在不同规模的网点节点下,具有较快的执行速度,能够较好地适应大规模网络拓扑结构的布局计算。

人工智能下的电站通信网络故障诊断与优化方法研究

为了实现电站通信网络故障快速定位,本文设计了一种基于卷积神经网络(Convolutional Neural Network,CNN)的电站通信网络故障诊断系统。本研究通过故障诊断系统的模型结构和可视化功能模块的设计,阐述了模型和故障诊断可视化的关键技术和流程,搭建并优化系统实现环境。最后文章所提出的模型与基线方法进行比较,证明所提出模型在精度等各个指标中均表现优异。系统可以利用基于CNN的故障诊断算法快速定位和诊断网络故障,实现网络拓扑的可视化过程和故障诊断。

Consensus of multiple autonomous underwater vehicles with double independent Markovian switching topologies and timevarying delays

A new method in which the consensus algorithm is used to solve the coordinate control problems of leaderless multiple autonomous underwater vehicles（multi-AUVs） with double independent Markovian switching communication topologies and time-varying delays among the underwater sensors is investigated.This is accomplished by first dividing the communication topology into two different switching parts,i.e.,velocity and position,to reduce the data capacity per data package sent between the multi-AUVs in the ocean.Then,the state feedback linearization is used to simplify and rewrite the complex nonlinear and coupled mathematical model of the AUVs into a double-integrator dynamic model.Consequently,coordinate control of the multi-AUVs is regarded as an approximating consensus problem with various time-varying delays and velocity and position topologies.Considering these factors,sufficient conditions of consensus control are proposed and analyzed and the stability of the multi-AUVs is proven by Lyapunov-Krasovskii theorem.Finally,simulation results that validate the theoretical results are presented.

A Visual Attention Model for Robot Object Tracking

Inspired by human behaviors, a robot object tracking model is proposed on the basis of visual attention mechanism, which is fit for the theory of topological perception. The model integrates the image-driven, bottom-up attention and the object-driven, top-down attention, whereas the previous attention model has mostly focused on either the bottom-up or top-down attention. By the bottom-up component, the whole scene is segmented into the ground region and the salient regions. Guided by top-down strategy which is achieved by a topological graph, the object regions are separated from the salient regions. The salient regions except the object regions are the barrier regions. In order to estimate the model, a mobile robot platform is developed, on which some experiments are implemented. The experimental results indicate that processing an image with a resolution of 752 × 480 pixels takes less than 200 ms and the object regions are unabridged. The analysis obtained by comparing the proposed model with the existing model demonstrates that the proposed model has some advantages in robot object tracking in terms of speed and efficiency.

Consensus of multi-vehicle cooperative attack with stochastic multi-hop time-varying delay and actuator fault

A consensus-distributed fault-tolerant(CDFT)control law is proposed for a class of leader-following multi-vehicle cooperative attack(MVCA)systems in this paper.In particular,the switching communication topologies,stochastic multi-hop timevarying delays,and actuator faults are considered,which may lead to system performance degradation or on certain occasions even cause system instability.Firstly,the estimator of actuator faults for the following vehicle is designed to identify the actuator faults under a fixed topology.Then the CDFT control protocol and trajectory following error are derived by the relevant content of Lyapunov stability theory,the graph theory,and the matrix theory.The CDFT control protocol is proposed in the same manner,where a more realistic scenario is considered,in which the maximum trajectory following error and information on the switching topologies during the cooperative attack are available.Finally,numerical simulation are carried out to indicate that the proposed distributed fault-tolerant(DFT)control law is effective.

Global Exponential Stability of Almost Periodic Solution of Cellular Neural Networks with Time-Varying Delays

In this paper, global exponential stability of almost periodic solution of cellular neural networks with time-varing delays （CNNVDs） is considered. By using the methods of the topological degree theory and generalized Halanay inequality, a few new applicable criteria are established for the existence and global exponential stability of almost periodic solution. Some previous results are improved and extended in this letter and one example is given to illustrate the effectiveness of the new results.

AN APPLICATION OF TOPOLOGICAL METHOD TO ANALYSING THE THREE-DIMENSIONAL FLOW IN CASCADES(Ⅱ)-TOPOLOGICAL ANALYSIS ON THE VECTOR FIELD PATTERNS OF SKINFRICTIONS AND SECTION STREAMLINES

With an application of topological analysis,in this paper the skin-friction line patterns on compressor and turbine cascade surfaces are depicted and the streamline patterns of the secondary flow fields in the cross-section of a curved pipe and a turbine cascade are drawn under given conditions.In addition the structures of vortices within three-dimensional viscous flow fields in cascades are analysed.

基于视觉动力形式的康护辅具轻量化设计研究

目的为了减轻和缓解用户物理负担和心理负担,对康护辅具进行轻量化设计,探索一种产品形态轻量化与结构轻量化并行的综合设计方法。方法以保护靴为例,将轻量化意象作为形态设计目标,采用语义差法和主成分分析得到轻量化意象及其典型代表样本;采用视觉动力形式分析建立产品形态轻量化意象的映射关系,并在此关系上通过曲线控制法进行初始形态方案设计;利用SolidWorks软件进行拓扑优化,判断材料冗余部分,为结构减重提供指导;再次结合映射关系对初始形态进行形态优化设计,得到最终设计方案。结论对保护靴设计方案进行评估,仿真结果显示方案重量降低近40%,评价结果显示轻量化意象评价良好,表明了该方法的可行性,为康护辅具的轻量化设计提供了新思路与方法。

视觉皮层下通路与拓扑知觉

研究表明,视觉通路除了经典的视觉皮层通路外,还有一条“古老的”、快速的皮层下通路负责在有意识和无意识状态下快速处理与情绪相关的信息。皮层下视觉通路由上丘、枕核和杏仁核组成,而且不经过初级视觉皮层。我们前期研究表明,初级视觉皮层与拓扑知觉信息加工没有关系,而皮层下视觉通路负责处理视觉拓扑信息。基于这些发现,我们认为,在早期视觉中,大脑检测涉及生命攸关的信号,这些信号告诉大脑:环境中有物体出现或消失,使大脑进入警戒状态,这对物种的生存至关重要。因此,在早期视觉中,需要检测的要素只是物体的“出现”和“消失”,而不是“纹理”、“形状”等。“出现”和“消失”都是拓扑特征的变化。拓扑感知和皮层下视觉通路的存在可能是早期预警的神经基础。在灵长类动物中,视网膜外周区域主要由视杆细胞构成,该区域接收的视觉信息主要通过皮层下视觉通路进行处理;视网膜中心区域(即中央凹)主要由视锥细胞构成,视觉空间分辨率变得非常高,该区域视觉信息处理主要是由视觉皮层负责。研究表明,由视杆细胞构成的视网膜是个“古老”结构,在1亿多年前就出现了;而视锥细胞构成的视网膜类型较为“年轻”,在5000万年前才出现。所以,我们的视网膜从“古老”结构演化到“年轻”结构至少用了5000万年的时间,它是由一个古老结构和一个年轻结构共同组成的“嵌合体”。当我们讨论皮层下通路存在的意义时,我们也应该结合皮层通路的功能来统一考虑。