Generalized dynamic covers for linear systems with applications to deterministic identification and realization problems

Several deterministic identification problems, with partial realization being a special case, are unified in the framework of the mathematical problem "generalized dynamic covers." An algorithm to find such a minimal dynamic cover as well as a uniqueness criterion is given, which yields several identifiability results. This problem also includes the "observer" and the "exact model matching" problems, as well as the problem of finding "minimal inverses for linear systems with arbitrary initial states." It is shown that the problem of finding minimal realizations from a transfer function matrix can also be solved in this framework.     

A generalized framework for interactive dynamic simulation for multirigid bodies

This paper presents a generalized framework for dynamic simulation realized in a prototype simulator called the Interactive Generalized Motion Simulator (I-GMS), which can simulate motions of multirigid-body systems with contact interaction in virtual environments. I-GMS is designed to meet two important goals: generality and interactivity. By generality, we mean a dynamic simulator which can easily support various systems of rigid bodies, ranging from a single free-flying rigid object to complex linkages such as those needed for robotic systems or human body simulation. To provide this generality, we have developed I-GMS in an object-oriented framework. The user interactivity is supported through a haptic interface for articulated bodies, introducing interactive dynamic simulation schemes. This user-interaction is achieved by performing push and pull operations via the PHANToM haptic device, which runs as an integrated part of I-GMS. Also, a hybrid scheme was used for simulating internal contacts (between bodies in the multirigid-body system) in the presence of friction, which could avoid the nonexistent solution problem often faced when solving contact problems with Coulomb friction. In our hybrid scheme, two impulse-based methods are exploited so that different methods are applied adaptively, depending on whether the current contact situation is characterized as "bouncing" or "steady." We demonstrate the user-interaction capability of I-GMS through on-line editing of trajectories of a 6-degree of freedom (dof) articulated structure.     

A note on observability tests for general polynomial and simple Wiener–Hammerstein systems

We propose an algorithm, based on symbolic computation packages, for testing observability conditions of general polynomial systems, which were formulated in Sontag, SIAM J. Control Optim. 17 (1979) 139–151. Computational complexity of the observability test can be reduced and the test simplified for classes of polynomial systems. We illustrate this by considering the class of simple Wiener–Hammerstein systems, which consist of a series of two linear dynamic blocks between which a static nonlinearity is “sandwiched”. We consider the case when the nonlinearity is a monomial . Simple necessary and sufficient conditions for observability are given and they resemble, but are subtly different from, the well known result on observability for the series connection of two linear systems.     

Decentralized $H_{infty }$ Filter Design for Discrete-Time Interconnected Fuzzy Systems

This paper describes a decentralized $H_{infty }$ filter design for discrete-time interconnected fuzzy systems based on piecewise-quadratic Lyapunov functions. The systems consist of $J$discrete-time interconnected Takagi–Sugeno (T–S) fuzzy subsystems, and a decentralized $H_infty$ filter is designed for each subsystem. It is shown that the stability of the overall filtering-error system with $H_{infty }$ performance can be established if a piecewise-quadratic Lyapunov function can be constructed. Moreover, the parameters of filters can be obtained by solving a set of linear matrix inequalities that are numerically feasible. Two simulation examples are given to show the effectiveness of the proposed approach.      

The Need for Software Engineering

Early in this decade a set of programming practices began to appear that seemed to offer a way out of the software difficulties accompanying the development of large systems. These practices, developed by Brooks,1 Baker,2 Dijkstra,3 Mills,4,5 and others, included structured programming, top-down development, chief programmer teams, HIPO (hierarchy/input-process-output) documentation, development support library, and structured walk-throughs. But despite the increasing amount of software development ment and its rising cost relative to the defense budget, corporation expenditures, and even the gross national product, the new programming techniques have not been adopted by acclamation. McClure,6 surveying the scene at COMPCON '76 Spring, saw "the great masses of programmers conducting their business exactly as they did five years ago." Nor was there the slightest sign in McClure's 5-year projection of "strong winds of change." His intuition was later supported by a survey of major Los Angeles area corporations,7 which concluded that, for all the fanfare, "the techniques are simply not widely used."     

“空”“有”相生魅力无穷

古人说"计白当黑,奇趣乃出",黑和白、虚和实像骨肉一样相连,形影相随、不可分离。白即空白也是最为巧妙的语言形式。"空白"并非空无一物,它是各类视觉元素之间的一种相互的关系以及这种关系造成的一种力。"空"和"有"是一对循环往复且又互相对立转换的自然状态,这就使得"空白"的设计研究具有了广袤的趣味价值。     

Refactoring Tools: Fitness for Purpose

Refactoring tools can improve the speed and accuracy with which developers create and maintain software—but only if they are used. In practice, tools are not used as much as they could be; this seems to be because sometimes they do not align with the refactoring tactic preferred by most programmers, a tactic the authors call "floss refactoring." They propose five principles that characterize successful floss-refactoring tools—principles that can help programmers to choose the most appropriate refactoring tools and also help toolsmiths to design tools that fit the programmer's purpose.     

面向嵌入式机顶盒终端的P2P网络电视直播系统的设计与实现

针对当前IPTV直播应用中,集中服务模式对服务器性能和网络设施要求较高、可扩展性较差的问题,提出了一种基于P2P(点对点)技术的直播系统Clear Live。与现有的P2P视频系统只针对PC终端的情况不同,该系统主要面向IPTV应用,面向嵌入式机顶盒终端,并兼容PC终端。Clear Live针对机顶盒终端的特点和IPTV应用的环境做了适当的和针对性的设计。实际系统测试结果表明,Clear Live系统能在较低的硬件配置下为大量用户提供高质量的直播服务。     

Optimum control limits for employing statistical process control in software process

There is increasing interest in using control charts for monitoring and improving software processes, particularly quality control processes like reviews and testing. In a control chart, control limits are established for attributes and, if any point falls outside the limits, it is assumed to be due to special causes that need to be identified and eliminated. If the control limits are too tight, they may raise too many "false alarms" and, if they are too wide, they may miss special situations. Optimal control limits will try to minimize the cost of these errors. In this paper, we develop a cost model for employing control charts for software processes using optimum control limits which can be determined. Our applications of the model suggest that, for quality control processes like inspection, optimum control limits may be tighter than those commonly used in manufacturing. We have also implemented this model as a Web service that can be used for determining optimum control limits.     

An efficient model for studying the dynamics of frustrated systems

We present a model based on determinist cellular automata architecture for studying systems with frustrated interactions that present elemental excitations, such as magnetic monopoles. This model is especially designed to be applied for systems with components that have energy levels much higher than $kT$. This would imply that for these systems thermal fluctuations are negligible and they can be analyzed under the supposition that the dynamic is produced at zero temperature. This category includes artificial magnetic spin ice systems and donor and recipient electrical charge molecular systems. The dynamics of these systems can be simulated in real time with this model, with a minimum of computational requirements. It can be an excellent complement to Monte Carlo methods and in some cases can even replace them directly. In this report, we show the designed structure and some interesting results obtained in studying the dynamics of emergent magnetic monopoles in artificial spin ice systems and excitations in graphane molecular arrays.     

3D input for CAAD systems

It is often acknowledged that the main advantage of computer aided architectural design (CAAD) systems is that they can be used by architects to quickly and accurately evaluate alternative design solutions using a variety of performance measures which would be too time consuming to apply by hand calculation.To gain the full advantage of interactive CAAD requires the architect to use a computer terminal with graphic capabilities so that he can create and modify his design geometry in a form which can also be directly interpreted by the evaluate routines within the CAAD system. However, it is suggested that it is often difficult for the user of such conventional, graphic, CAAD systems to conceptualise the building being designed by only inspecting and manipulating drawings displayed on the terminal screen.This problem may be accentuated when building users who are not professional architects wish to use a CAAD system so as to participate in the design process.A computerised building block system (BBS) is proposed with which the designer can physically build a model of his design as he would if he was using ‘Lego’¹ blocks. Such a physical representation may allow him to evaluate many of the visual and spatial qualities of his design in a more direct way than could be achieved using computer graphics. However, because the electronic system can ‘read’ the arrangement of blocks and input this information into a computer, the user's design can be evaluated with the same performance measures that are used in existing CAAD systems.     

Anytime mining for multiuser applications

Database systems have been designed to serve multi-users in real-world applications. There are essential differences between mono- and multi-user applications when a database is very large. Therefore, this paper presents an "anytime" framework for mining very large databases which are shared by multi-users. Anytime mining is designed to generate approximate results such that these results can be accessed at any time while the system is autonomously mining a database.     

基于等效网络的车辆导航系统路线规划算法

在实际交通行为中,不可避免地存在着交叉口时间延迟,而且交通管制信息如交叉口转向限制也普遍存在,这些交通特征使得常规的最短路算法难以满足车辆导航系统路线规划的要求。提出基于“节点-弧段-特征”的数据结构存储方案,能够完整描述路网的平面拓扑和交通特征属性;针对具有交叉口转向限制和交叉口延迟等特征的交通网络,首先采用对偶图方法构造等效网络,在等效网络中采用常规的最短路算法计算最优路线,然后将它转化为原道路网中的行车路线。试验证明这种方法能够有效解决包含交通特征的车辆导航系统路线规划问题.     

Inventorying information technology systems: supporting the "paradigm of change"

One of the most significant failures of the IT profession is the absence of systems to gather, support, and supply information for managing software items. Most IT professionals, if they consider software management, think in terms of version or configuration control license and patch management. Version control systems (VCSs) and software configuration management (SCM) systems aim to manage versions of individual software objects with support for linking into sets for release purposes. This has nothing to do with addressing the issues of controlling large amounts of geographically disbursed software, executing on different kinds of systems, maintained by hundreds to thousands of programmers. Software systems are the only major organizational asset with no real support for managing them based on information technology. An appropriate IT inventory management facility is the cornerstone of an integrated set of technologies, called the "paradigm of change" designed to address constantly changing technologies and business processes.     

Design of a state estimator for a class of time-varying multivariable systems

In this note, matrix operators are first introduced to develop a canonical transformation. Then it shows that a full order state estimator with any eigenvalues can be constructed for linear time-varying systems that are uniformly observable and "lexicography-fixed." A simple algorithm is provided to design the state estimator.     

Covering arrays for efficient fault characterization in complex configuration spaces

Many modern software systems are designed to be highly configurable so they can run on and be optimized for a wide variety of platforms and usage scenarios. Testing such systems is difficult because, in effect, you are testing a multitude of systems, not just one. Moreover, bugs can and do appear in some configurations, but not in others. Our research focuses on a subset of these bugs that are "option-related"-those that manifest with high probability only when specific configuration options take on specific settings. Our goal is not only to detect these bugs, but also to automatically characterize the configuration subspaces (i.e., the options and their settings) in which they manifest. To improve efficiency, our process tests only a sample of the configuration space, which we obtain from mathematical objects called covering arrays. This paper compares two different kinds of covering arrays for this purpose and assesses the effect of sampling strategy on fault characterization accuracy. Our results strongly suggest that sampling via covering arrays allows us to characterize option-related failures nearly as well as if we had tested exhaustively, but at a much lower cost. We also provide guidelines for using our approach in practice.     

“妙手”系统机械结构设计与优化

为了辅助医生更好地完成显微外科手术,开发了一种主从异构的显微外科手术机器人系统——“妙手”系统．“妙手”系统的主手为商业化的Phantom Desktop主手,从手为针对显微外科血管缝合而设计的“妙手”从手．从手包括位置机构和姿态机构．位置机构通过丝传动实现双四连杆机构的运动特性;姿态机构采用三轴交汇于一点的设计思想．通过分析双四连杆机构的运动特性,根据Angeles运动灵活度指标对双四连杆机构进行了优化．结果表明：当双四连杆机构前三级杆等长且I级杆与III级杆垂直时,机构运动灵活度取最大值．