Finite-time target localization and multicircular circumnavigation with bearing-only measurements

This paper studies the finite-time localization and multicircular circumnavigation problem of an unknown stationary target via a networked multi-agent system using bearing-only measurements. To enhance the convergence rate of estimation, a novel estimator is developed to enable the agent to localize the target in finite time. At the same time, with the estimated target position, a distributed controller is designed such that the agents circumnavigate the target along different orbits with any prescribed angular spacing in finite time. In terms of Lyapunov theory and cascade control strategy, finite-time stability of the overall system including the estimator and controller are analyzed rigorously. Besides, the proposed algorithms guarantee that the agents can keep a safe distance from the target in the whole movement process, and high angular velocity can be avoided even if the circumnavigation radius becomes small. Finally, to corroborate the theoretical results, two simulation examples are given.     

Finite-time distributed localization and multi-orbit circumnavigation with bearing-only measurements

This paper investigates the localization and circumnavigation problem of a stationary target by multiple agents with multi-orbit within finite time. The agents can only obtain their own positions and the bearing information of the target. They are required to travel along their prescribed trajectories in three-dimensional (3-D) space and circumnavigate the target. First, a novel finite-time distributed positional estimator, using bearing-only measurements, is developed for agents to localize the target. Afterward, with the estimate of the target position, a distributed control law is designed to steer the agents to circumnavigate the target on different orbits with any preconcerted angular spacing distribution pattern within finite time. Simultaneously, the corresponding stability and convergence analyses are presented. Finally, simulation results are provided to demonstrate the effectiveness of the theoretical results.     

Finite-time cooperative circumnavigation control of multiple second-order agents with desired formations

This paper investigates the finite-time cooperative circumnavigation control of multiple second-order agents, in which the agents should surround a moving target with desired formation and circular velocity based on local information. Firstly, the controller design is transformed into design control parameters such that the error system, including distance error, speed error and angle error, is finite-time consensus. The error system is viewed as a cascaded system containing two second-order subsystems, and then a distributed finite-time controller composed of two parts is delivered. The finite-time stability of the entire system is given by employing cascaded control theory. One significant advantage of the proposed controller is that it allows the agents to converge to desired trajectory in a finite time instead of asymptotically. Another merit is that the desired formation is an extensive case and unlimited, including different tracking radii and angular spacing. Furthermore, the proposed controller can be implemented by each agent in its local frame, utilizing only local information. These properties significantly extend the application scope of cooperative circumnavigation. Finally, simulations are carried out to validate the effectiveness of the proposed method.     

Fixed-time anti-saturation grouped cooperative guidance law with state estimations of multiple maneuvering targets

The problem of a grouped multiple missiles cooperative attack on multiple high maneuvering targets with a limited driving force is achieved by an anti-saturation fixed-time grouped cooperative guidance (FxTCG) law based on a sliding mode fixed-time disturbance observer (SM-FxTDO) in this study. First, the state estimation of each high maneuvering target within a fixed time is achieved by designing a sliding mode fixed-time disturbance observer. Second, the group cooperative guidance law is designed by using fixed-time theory, which can ensure the group consensus of multiple missiles strike times within a fixed time under the condition of input saturation. Then, the fixed time stability of the multi-missiles system is proven by using the bi-limit homogeneous theory and the Lyapunov function. Finally, the simulation results show the superiority of the designed observer and cooperative guidance law. The proposed observer can more effectively and accurately estimate the state of the high maneuvering target than the ESO. The proposed cooperative guidance law expands the number of attack targets and makes each group of multiple missiles attack the corresponding high maneuvering target under the conditions of an input saturation within a fixed time compared to the single-target cooperative law.     

Source localization using TDOA and FDOA measurements based on semidefinite programming and reformulation linearization

The problem of source localization using time-difference-of-arrival (TDOA) and frequency-difference-of-arrival (FDOA) measurements has been widely studied. It is commonly formulated as a weighted least squares (WLS) problem with quadratic equality constraints. Due to the nonconvex nature of this formulation, it is difficult to produce a global solution. To tackle this issue, semidefinite programming (SDP) is utilized to convert the WLS problem to a convex optimization problem. However, the SDP-based methods will suffer obvious performance degradation when the noise level is high. In this paper, we devise a new localization solution using the SDP together with reformulation-linearization technique (RLT). Specifically, we firstly apply the RLT strategy to convert the WLS problem to a convex problem, and then add the SDP constraint to tighten the feasible region of the resultant formulation. Moreover, this solution is also extended for cases when there are sensor position and velocity errors. Numerical results show that our solution has significant accuracy advantages over the existing localization schemes at high noise levels.     

Operational space consensus of multiple heterogeneous robots without velocity measurements

This paper proposes a control algorithm for networks of multiple heterogeneous robot manipulators, which solves the leader–follower and the leaderless consensus problems in the operational space. In the leader–follower scenario, the controller ensures that all the robots in the network asymptotically reach a given leader pose (position and orientation), provided that, at least, one follower robot has access to the leader pose. Without a leader pose, in the leaderless problem, the robots asymptotically reach a pose of consensus. The controller is a simple distributed proportional plus damping injection (P+d) scheme which does not require velocity measurements. A singularity-free representation, unit quaternions, is used to describe the orientation of each manipulator. The paper presents some simulations, with a network of six 6-Degrees-of-Freedom (DoF) manipulators, and experiments, with a network of three 6-DoF manipulators, to show the effectiveness of the proposed controller.     

具有钝化和激活效应的合作超网络演化机制研究

［目的/意义］合作网络研究是近年来学者关注的一个热点问题,然而传统的网络分析方法只适合刻画两两合作者之间的合作关系,深入分析现实世界中的多人合作关系及其网络发展、演化机制,具有重要的现实意义。［方法/过程］引入超网络理论,构建节点具有钝化和激活状态的演化模型,探讨随机和择优两种驱动机制对合作网络演化过程的影响。仿真发现,择优机制驱动下点超度分布呈幂律分布;随机机制驱动下点超度分布呈指数分布。［结果/结论］选取现实合作网络的数据进行实证分析,实证结果与仿真结果相吻合。说明理论模型对于刻画现实合作网络具有一定的参考价值。     

企业间合作治理模式选择及其绩效研究述评

按照“交易特征—治理模式—经济效率”的分析框架,梳理了企业间合作治理模式划分、合作治理模式选择影响因素以及合作治理模式选择对合作绩效影响等三方面的研究成果。在此基础上,提出了未来研究的方向,认为合作治理模式选择对合作绩效影响的研究将是未来研究的前沿。     

碳限额下合作努力减排的协调研究

研究分散式供应链下,单个制造商和多个供应商合作努力减排机制。当单个制造商生产某产品时需要多个供应商提供一组供应活动时,各方共同投入以减少供应活动的单位碳排放。研究表明,在批发价格合同和成本加成定价合同这两种传统类型的合同中,参与方的个人最优减排努力偏离了集中式系统的最优解。为了激励供应链的参与方共同参与减排,开发合作努力减排合同,使各参与方分享合作减排收益,共同积极减少碳排放,使供应链达到协调。     

风险厌恶下合作研发的双边激励合同

通过构建基于纳什谈判的团队生产模型,在风险厌恶下考察合作研发的双边激励和谈判问题.分析研发组织的研发效率、风险厌恶以及产出波动等因素对线性激励合同的影响,研究表明:一方所得最优线性分享比例随自身(对方)研发效率的上升而增大(下降),随自身(对方)风险厌恶程度的上升而减小(增大);而最优线性分享比例随研发产出方差的变化依赖于两个组织的风险厌恶程度与研发效率乘积的相对大小;最后剖析了风险厌恶、谈判能力、研发效率和产出波动等因素对激励合同及研发产出的影响机理.     

供应商竞合目标影响企业创新和新产品开发绩效的机制

基于合作与竞争理论探讨企业与供应商之间目标关联影响企业创新和新产品开发绩效的作用机制。运用结构方程模型对233家企业数据进行分析,结果表明:合作目标通过推动供应商整合促进探索式创新和利用式创新,进而增强核心能力并最终提高新产品开发绩效;相反,竞争目标通过抑制供应商整合阻碍探索式创新和利用式创新,进而减弱核心能力并最终降低新产品开发绩效。     

影响合作性学习效果的因素及其干预对策

合作性学习是目前教学改革中广泛采用的一种教学方法,研究发现,学生对于学习方案的理解程度、组内人际关系、教师对教学过程的控制、指导能力、学生对于学习的兴趣都会影响到最终的学习效果。增加对学习方案的讲解、建立良好的组内人际关系、加强教师培训提高其指导能力、通过合理的手段激发学习兴趣将对提高合作性学习的效果起到良好的作用。     

New SI and precision measurements: an interview with Tianchu Li

On 13–16 November 2018, the 26th General Conference of Weights and Measures (CGPM) was held in Paris. The conference adopted Resolution A on ‘Revision of the International System of Units (SI).’ According to Resolution A: four of the SI basic units, namely kilograms, amps, kelvin and mole, are defined by the Planck constant h, the basic charge constant e, the Boltzmann constant k and the Avogadro constant N_A, respectively. This establishes the basic quantities and units in SI on a series of constants. The new SI was officially launched on 20 May 2019. This is the most significant change and a milestone in the history of metrology since the Metre Convention was signed in 20 May 1875. Professor Tianchu Li, an academician of the Chinese Academy of Engineering, has been working on time and frequency standards for 37 years. In this interview, Prof. Li reviews the quantization and constant evolutions of the second and meter, and introduces the redefinitions of ampere, kelvin, kilogram and mole, and their significance for precision measurements.     

Cooperative output regulation problem of multi-agent systems with stochastic packet dropout and time-varying communication delay

In this paper, we deal with the cooperative output regulation problem of linear multi-agent systems on a directed network topology subject to both stochastic packet dropout and time-varying communication delay. On the basis of introducing a queuing mechanism, a distributed state feedback control algorithm is proposed. Then the continuous-time multi-agent systems with piece-wise constant control are converted into discrete-time systems. Under some standard assumptions, the necessary and sufficient conditions under which the tracking errors of followers approach to the origin asymptotically are proposed for different exosystems. Finally, the proposed results are verified via two examples.     

吉林省服务业与日韩合作竞争情报战略研究

吉林省服务业近年来取得了较好的成绩,但在与国外合作方面还存在严重不足。本文以吉林省服务业整体行业作为研究对象,调查了长吉图背景下吉林省服务业与日韩合作的优势、劣势、机遇与挑战,对吉林省与日韩服务业合作竞争情报建立了SWOT分析模型,进而提出了服务业的发展路径与政策支持。     

企业能力差异与合作创新动机

企业参与合作创新主要有两个方面的动机，成本共享和技术共享，合作伙伴间能力的差异对合作动机重要，本文通过一个有知识溢出的两个阶段双寡头博弈模型，比较了自主创新、成本共享、技术共享几种创新方式的均衡结果，得出结论：当企业具有同质的资源和能力时，成本共享是企业合作创新的主要动机，当企业的能力互补时，技术共享是企业合作创新的主要动机。     

Modelling innovation and imitation sales of products with multiple technological generations

Majority of consumer durables have multiple technological generations. Each succeeding generation offers some innovative performance enhancements, feature additions etc. distinguishing itself from the past releases. Therefore the consumer's attitude towards each of them can be very different. There is a need to understand consumer psychology and have accurate measure to predict the adoption process of new technology. Mathematical models have proved to be ideal tools to explain the past purchasing-behavior and also for forecasting. This paper focuses on studying the relative changes of diffusion parameters for both first time purchasers and upgraders along with developing a more general sales model for multiple technology generation products. The proposed model explicitly identifies different groups of purchaser viz. first timers and repeaters (upgraders).     

论教与学协作的有效性

在新课改的推动下,协作学习越来越受到人们的重视。教与学的协作,不仅突出了教师教学的重要性,也体现了学生学习的主体性,然而在教师教学与学生学习的协作的过程中往往存在定位不准、流于形式、偏离主题以及缺乏引导等问题。从存在问题的原因来看,强化协作认知力、提高协作参与度、关注协作平等性以及评价协作多元化应是教与学有效协作的基本策略。     

论教与学协作的有效性

在新课改的推动下,协作学习越来越受到人们的重视。教与学的协作,不仅突出了教师教学的重要性,也体现了学生学习的主体性,然而在教师教学与学生学习的协作的过程中往往存在定位不准、流于形式、偏离主题以及缺乏引导等问题。从存在问题的原因来看,强化协作认知力、提高协作参与度、关注协作平等性以及评价协作多元化应是教与学有效协作的基本策略。