Sampling of a system with a time delay

This note deals with the problem of sampling a continuous-time system which contains a time delay. It is shown that the infinite-dimensional continuons-time system can be represented by a finite-dimensional sampled data system. It is shown that there are simple expressions for the sampled data state-space representations.     

The design of a fuzzy system shell using a database approach

This study presented a prototype of fuzzy system shell called FuzzyAccess. Using Microsoft Access database as a developing tools, the proposed system provided a friendly interface for user self-building a fuzzy system. A novice who has no programming-knowledge can also self-define a new fuzzy project. The main contributions of the proposed system were that using SQL method to search the candidate rules in rule evaluation stage and providing an integrated tuning interface for system adjustment. The SQL method can significantly reduce the search time in rule evaluation. The integrated tuning interface can assist user quickly inspecting the influence among different system parameters adjustment and reducing the system development time.     

The development of a panorama manifestation virtual reality system for navigation and a usability comparison with a desktop system

The virtual reality (VR) system has become popular in the last two decades and is being applied increasingly to navigation studies. This study developed a panorama manifestation (PM) VR system, with six monitors forming a circular display and an interactive chair equipped with rotation sensors and operating knobs. The advantages of the PM system include a large circular display, a body-centred design, body engagement and a low set-up cost. Based on navigation experimental tasks, this system's usability was compared with that of a typical desktop (DT) system. The results showed that participants using the PM system had a significantly higher success rate and required less completion time than participants using the DT system, indicating that the PM system outperforms the DT system in terms of effectiveness and efficiency in some navigation tasks, and also suggesting that the PM system may require lower spatial cognition workload in the navigation tasks. However, the participants’ subjective evaluations of task difficulty (TD) failed to reach significance although the PM group did report a lower mean value for TD. Additionally, in the PM system, the participants’ spatial ability was more predictive to their navigation performance than that in the DT system, indicating that the PM system offered greater usability for some spatial experiments and could provide more support for participants’ navigation tasks.     

混沌系统与稳定系统的同步控制研究

通过对异结构混沌系统的广义投影同步进行分析研究,发现其本质为利用驱动系统的输出信号构造合适的非线性反馈控制器,使得响应系统具有和驱动系统相一致的拓扑结构,从而两系统可以同步.在此基础上,认为只要构造一个合适的控制器就有可能使得一个混沌系统和任意一个系统发生同步,数值仿真主要针对一个稳定系统,构造合适的非线性反馈控制器,实现其和一个四维混沌系统的广义投影同步,表明了理论推导的正确性和所设计的控制器的有效性.     

Flexibility in a minicomputer c.a.d. system: a new approach

Valuable flexibility can easily be introduced into a computer-aided design system, enabling the range of computable properties to be greatly increased. By typing an expression for a property of interest, using the APL notation, a personal version of the system suited to the designer's needs can be created in a few seconds. Illustrations of the approach are based on the MINNIE system for circuit design.     

Reaching a consensus: a discrete nonlinear time-varying case

In this paper, we have considered a nonlinear protocol for a structured time-varying and synchronous multi-agent system. By means of cubic triple stochastic matrices, we present an opinion sharing dynamics of the multi-agent system as a trajectory of a non-homogeneous system of cubic triple stochastic matrices. We show that the multi-agent system eventually reaches to a consensus if either of the following two conditions is satisfied: (1) every member of the group people has a positive subjective distribution on the given task after some revision steps or (2) all entries of some cubic triple stochastic matrix are positive.     

A model of a trust-based recommendation system on a social network

In this paper, we present a model of a trust-based recommendation system on a social network. The idea of the model is that agents use their social network to reach information and their trust relationships to filter it. We investigate how the dynamics of trust among agents affect the performance of the system by comparing it to a frequency-based recommendation system. Furthermore, we identify the impact of network density, preference heterogeneity among agents, and knowledge sparseness to be crucial factors for the performance of the system. The system self-organises in a state with performance near to the optimum; the performance on the global level is an emergent property of the system, achieved without explicit coordination from the local interactions of agents.     

Construction of a robot control system which understands a voice and pointing actions

This research was aimed at making a robot that can go and get an object designated by the user. We produced a robot control system that uses pointing and voice control. This control system is composed of two systems. One system is the object instruction system that uses pointing, and the other is the object instruction system that uses voice. The approximate position of a designated object is recognized by the object instruction system that uses pointing, and information about the object and instructions about the operation are conveyed by the object instruction system that uses voice. This time, the object instruction system that uses pointing has been designed and verified as the first step. A calculation resource to calculate the approximate position of the designated object is obtained when the user points directly at the object. A robot can be moved around a designated object by using this system. The object instruction system that uses voice will be constructed in future work.     

Two-time correlation functions of a two-level system influenced by a composite environment

To study the quantum regression theorem and the Leggett–Garg inequality, two-time correlation functions are calculated for a two-level system which is placed under the influence of a composite environment consisting of two subsystems. Two different configurations, I and II, are considered. In the configuration I, a two-level system of interest interacts with a thermal reservoir via another two-level system. In the configuration II, a relevant two-level system is influenced independently by another two-level system and a thermal reservoir. In both configurations, the thermal reservoir is assumed to have a sufficiently short correlation time. When an interacting nuclear-spin and electron-spin system is considered, the relevant system is a nuclear-spin (electron-spin) in the configuration I (II). It is shown that the quantum regression theorem for the relevant two-level system is always valid in the configuration II while it is not in the configuration I, regardless of whether the reduced time evolution is Markovian or not. Furthermore, it is found that the Leggett–Garg inequality can be violated in both configurations. The dependence of the violation on the parameters characterizing the open two-level system is investigated.     

Nonlinear control of a coupled PDE/ODE system modeling a switched power converter with a transmission line

We consider an infinite dimensional system modeling a boost converter connected to a load via a transmission line. The governing equations form a system coupling the telegraph partial differential equation with the ordinary differential equations modeling the converter. The coupling is given by the boundary conditions and the nonlinear controller we introduce. We design a nonlinear saturating control law using a Lyapunov function for the averaged model of the system. The main results give the well-posedness and stability properties of the obtained closed loop system.     

Design of a coating system using SIMAN: a case study

In this paper, we analyze four different operating methods of the coating system for Electronic Display Tube(EDT). The objective of this study is to develop new coating system design principles which are flexible and efficient in multi-product simultaneous production. We use SIMAN as a tool for the system analysis, and the criteria for comparisons with the existing systems are based on flexibility and efficiency. We had operated the existing systems with fixed four different product patterns, but have found more flexible input patterns through simulation analysis and the productivity has been improved. We have also developed a few principles to enhance the system performance and more efficient new coating system design.     

Dynamic behaviour of a mechanical system of which a part performs a prescribed relative motion

A method is presented to solve by means of a finite element analysis the problem of the dynamic behaviour of a mechanical system, a part of which performs a prescribed relative motion. The kinematic coupling of this part to the rest of the system and the derivation of the matrix equations of motion are discussed, as well as the applied condensation method. Moreover the results of a computation based on this method are compared to those obtained by neglecting the dynamic interactions of both the parts of such a mechanical system.     

水电站发电机组动态特性的在线辨识

本文介绍了在某水电站发电机组处于不同运行方式下在线辨识的试验结果,试验结果表 明,应用伪随机信号相关仪在电力系统中进行在线辨识是安全可行的,并且看出单台发电机组 的动态特性与电力系统的结构和潮流有关.     

Torque distribution using a weighted pseudoinverse in a redundantly actuated mechanism

When mobility, the number of independent variables to describe system motion exactly, is greater than the degree-of-freedom of task space, the system is called a kinematically redundant system. On the other hand, redundant actuation indicates a situation when there are more actuators than a system's mobility. Redundant actuation yields many advantages. First, actuation redundancy can increase the force, velocity and acceleration of an end-effector. Second, if some actuators are out of order, the system can still work well. This fault-tolerant capability is useful for remote control robots in space or nuclear plants. Impulsive force can decrease when modulating arbitrary stiffness without feedback control. The performance of a system can be improved by optimizing redundancy. However, there are some issues of economic efficiency and minimization of a system, because redundant actuation may involve more actuators than non-redundant actuation. In addition, there are infinite torque sets of motors for the same task. We used a weighted pseudoinverse matrix for torque distribution. To reduce the maximum torque, we suggested the use of the minimum norm torque as the weighting values. This method allows for smaller motor capacity, and can contribute to economic efficiency and minimization of a system.     

Quasi-Static Motion of a Two-Link System along a Horizontal Plane

Quasi-static motion of a two-link system along a rough horizontal plane is considered. Dry friction acts between the links of the system and the plane. During the motion, the configuration of the linkage changes, whereas the points of contact of the linkage and the plane remain the same. The control torque applied at the joint of the linkage is chosen so as to provide equilibrium condition for each of the links. It is shown that the quasi-static motion of the two-link system is uncontrollable and the uniqueness of this motion is proved for given initial position of the linkage. The trajectories of the vertices are found, depending on the parameters of the system.     

Designing a Controller for a Multi-Train Multi-Track System

The use of formal methods for analyzing and synthesizing a controller for a multi-train multi-track railway system is discussed. The research was motivated by a case study involving the Bay Area Rapid Transit (BART) system. The overall goal is to design a train acceleration control function that enables trains to be safely placed but also increases system throughput. The use of a modeling language for specifying safety properties and a control function is illustrated. The program transformation methodology supported in the HATS system is employed to generate an efficient implementation from a high-level specification of a controller. This implementation can then be used to simulate the controller behavior, thus further enhancing confidence in the design. Properties of optimization transformations can be verified using an rewrite-rule based induction theorem prover Rewrite Rule Laboratory (RRL).     

On multiple-objective optimal model of a memoryless system with a cascade structure

The paper deals with a probabilistic case of the identification problem of a complex system consisting of two memoryless elements connected in a cascade or tandem system. The non-parametric cascade model, optimal from the viewpoints of the system as a whole, as well as its individual elements, is discussed. Both theoretical and empirical criteria of the existence of such a model are given and the procedure of the optimal system model determining is outlined.