Towards a service-enabled distributed router architecture

Modelling is an essential tool in the development and assessment of new concepts. The authors propose an architecture for the next-generation gigabit distributed active router that was designed and implemented in the IST project, FlexiNET. In the FlexiNET project, a service called 'dynamic service deployment' dynamically installs, monitors and uninstalls new services on user demand or by default configuration. The proposed distributed router architecture achieves scalability of performance, functional flexibility and reliability. Scalability is achieved by adding new modules that have identical interfaces in an extensible function block. New services can easily be added by inserting modules that have the appropriate functionality. Another significant aspect of the model presented is that a failure in one module does not affect the other modules because they operate independently.     

民用飞机机载电子系统分布式体系架构研究

为了解决机载电子系统处理平台高度综合带来系统资源竞争及深度耦合的问题,将系统综合扩展到前端机电领域,采用分布式综合模块化机载电子系统(DIMA)架构理念,把计算资源分离到与信号源相近的区域,以分离式小机柜取代集中式大机柜,采用高速总线进行分布式机柜互联,重点分析了航电全双工交换式以太网(AFDX网络)、时间触发式以太网(TTE网络)、基于以太网的无源光网络(EPON网络)在DIMA系统中的应用,对比了这3种总线网络技术特点,最后以空客分布式机载电子系统架构为例分析了分布式机载电子系统架构的优势和特点．通过采用DIMA系统架构,解决了机载电子系统处理平台资源竞争和深度耦合问题,同时简化了背板结构,在民用飞机上具有广阔的应用空间．     

基于面向服务架构的分布式开放控制系统

提出了一种基于面向服务架构(SOA)的分布式开放控制系统模型.整个参考模型由设备抽象层、基本控制模块层、服务层和应用层四层组成.各层内部采用面向对象的方法进行设计,各层相对独立,层间的耦合性比较小.服务层包含了所有分布式子系统的服务抽象和封装,以服务的方式供应用层使用.这种控制系统模型,开放性好,各个模块的可重用性强,开发效率高.使用这种框架,成功开发了IC工艺装备中的刻蚀机硅片传输原型系统,而且取得了很好的效果.     

A client-server architecture for distributed measurement systems

This paper describes a client-server architecture for the remote control of instrumentation over the Internet network. The proposed solution allows multiuser, multi-instrument sessions by means of a queueing and instrument locking capability. Client applications can be easily developed by using conventional high-level programming languages or well-assessed virtual instrumentation frameworks. Performance tests are reported; they show the low overhead due to network operation with respect to the direct control of instrumentation     

A distributed measurement architecture for industrial applications

In this paper, a distributed digital measurement architecture for industrial applications is proposed. The architecture is arranged on three hierarchical communication levels: the fieldbus, the intranet, and the Internet. Particular attention has been paid to the lower level, the field level, implemented using a low-priced smart front-end. It is based on the H8/3048F Hitachi microcontroller and embodies a fieldbus interface (I/F). The same board can be linked to a VXIbus controller by means of a suitable register-based interface. The proposed network can embody a number of analog signal conditioning circuits, processor, and communication capabilities, to meet the industrial needs. We propose two applications of this distributed measurement architecture: the monitoring of power quality in an electrical distribution network and the management of a water distribution system. Experimental results showing the system performance are also included in the paper.     

Managing object schemas in a distributed database architecture for concurrent engineering

Abstract

In recent years, object database systems have emerged as a new technology, integrating object‐oriented paradigms with transaction and query capabilities of conventional database systems. The strength of distributed object database systems is further enhanced by new generations of powerful workstations. The synergy between object databases and the networked workstation environment, however, brings forth a new set of challenges. In this paper, we address the issues of managing object schemas in a cooperative network environment. After reviewing existing solutions, we present a more dynamic approach to the problem of distributed schema management. We also show how this approach can serve as a general framework for supporting various schema management policies.     

An open distributed measurement system based on an abstract client-server architecture

This paper describes in detail a Java-based, client-server architecture specifically designed to allow a flexible management of remote instruments. The main attributes of the proposed solution are portability and extensibility. The former feature is assured by the employment of the TCP/IP protocol suite and by the Java language properties. The latter is due to the high level of abstraction of the system implementation. This approach addresses a wide range of possible applications with high code reusability. In fact, the proposed architecture permits to drive many kinds of different devices and can be easily upgraded simply by adding a limited amount of code on the server computer whenever a new instrument is connected to the system.     

Epoch-by-epoch GPS ambiguity processing for local network-based positioning

When processing code- and carrier-phase ranges sampled at individual epochs, the control baseline of a pair of reference receivers can bring forth relative integer-valued ambiguities and tropospheric delays. The estimates are usually so accurate that they may act as constraints, when a roving user who operates in the network of references requires instantaneous position solutions. This paper has the objective of taking advantage of a tropospheric zenith delay surface for the user’s ranging corrections. A local network of six reference stations was used to study the single-epoch position estimation, which revealed that with the increased reliability of ambiguity resolution on both L1 and L2 carriers, global positioning system-derived height accuracy was refined by more than 60%.     

Distributed architecture of an adaptive positioning servo

A distributed computer architecture which offers high precision and high-speed computing capabilities that are needed when complex system identification and controller adaptation algorithms are implemented in real time. The distributed implementation offers high immunity against external disturbances. An elevator control application is considered. However, the principles presented are applicable to different types of industrial automation problems. The individual computer units in this system are programmable VLSI signal processors (e.g. TMS-320C25). All the precision-sensitive computations are performed using simulated single-precision floating-point arithmetic (IEEE Standard 754). This is possible because of the high speed of the signal processor and low sampling rate (i.e. ⩽100 Hz) of the entire positioning servo. The communication between the master controller and the slave units is coordinated by a simple communication protocol that utilizes a prediction-type transmission error correction principle     

High track density for magnetic disk drives with an "Embedded servo" positioning system

The CII-HB "Embedded servo" original technique for disk drive units (such as the D 160) allows operation at high track densities ( 800 TPI) and fast access time. The overall information needed for head displacement and positioning is provided by the data head itself, without any other transducer. Servo transitions, written between the data sectors, are arranged to provide gain information, track logical address, and fine position. This information is used by a microcomputer program to move the head rapidly to the desired track and to lock it in position within an instantaneous error of less than 3 μm (120 μm inches). Practical results are presented and compared with a theoretical model. Limitations and improvements are discussed.     

Agent-based fractal architecture and modelling for developing distributed manufacturing systems

For their timely response to the rapidly changing manufacturing environment and markets, future manufacturing systems must be flexible, adaptable, and reusable. Recently, bionic (or biological), holonic, and fractal manufacturing systems (FrMS) have been discussed as potential candidates for the next generation of manufacturing systems. This study focuses on the FrMS, which is based on the concept of autonomous cooperating agents referred to as fractals. The major component of the FrMS is a basic fractal unit (BFU). It consists of five functional modules: observing module (observer), analysing module (analyser), resolving and executing module (resolver), organizing module (organizer), and reporting module (reporter). Although the FrMS has many conceptual advantages, the implementation of the system has been known to be difficult. This paper is a preliminary study of the basic components and the architecture with an eye toward the future implementation of FrMS. In order to describe the characteristics of a fractal, this paper presents several models including function models using IDEF0, working models using Petri-net, and static/dynamic models using the unified modelling language (UML).     

Fiber-optic sensor system for rapid positioning of a microelectrode array

A fiber-optic intensity sensor has been developed for vertically positioning microelectrode arrays above the retina of a live frog. Closely spaced fibers illuminate and collect reflections from the retinal surface, and the output is electronically processed to drive an automated positioning circuit. Experimental and theoretical evaluations of fiber types and separation for both specular and diffuse reflectors, in vitro and in vivo, are presented, and multimode fibers on 125-mum centers are chosen for retinal experimentation. The sensor has applications in assessing spatial selectivity of stimulation of a multielectrode array and may be adaptable for lateral positioning.     

Reduced processing element architecture for parallel local image processing

Abstract

The object of this paper is to propose new architecture which can reduce the number of processing elements for parallel local image processing under the premise of real‐time performance. For large‐sized local image processing, this architecture will save much space as it is suitable for being designed into VLSI chip. For example, the traditional parallel architecture will use 9 PEs for a 3×3 convolution, while the Reduced Processing Element Architecture (RPEA) only requires 2 PEs to achieve the real‐time performance.     

数字化光电跟踪伺服系统定位极限环的抑制

数字光电跟踪系统定位时将产生自振荡,在相平面下可描述为极限环。自振荡对定位精度影响较大,因此必须对其进行抑制。针对实际的数字光电跟踪伺服系统,提出一种描述方法,即用等效间隙非线性来描述其定位时非线性特性,且该间隙主要由光电传感器的滞后效应和伺服系统的摩擦死区引起。理论分析表明,双极PWM功率放大器的零点振颤特性可以抑制伺服系统的定位极限环。实验也证明,通过软件补偿以及PWM驱动模式设计来改善光电跟踪系统定位精度是可行的,定位精度由1.77提高到了22.23,大大抑制了定位非线性特性。     

Magnet system for a superconducting magnetic separator

A magnetic separator with superconducting magnets has been designed, constructed and successfully tested. Its application is sorting finely ground ores or minerals with low susceptibility. The system can be described as a superconducting drum separator combining the advantages of the well known reliable conventional drum separators with the advantage of high magnetic field economically produced by superconducting magnets. This laboratory magnetic separator with a relevant drum diameter of 1 m served as a first step on the way to an industrial pilot plant. This paper reports on design, construction, and test of the sc magnet system and its supply.     

Development of a parallel processing multi-agent architecture for a virtual CIM system

Global manufacturing enterprises tend to rely on fully integrated manufacturing systems to satisfy constantly changing market requirements. In addition, small to medium enterprises are in a dilemma when competing with large organizations. Virtual computer-integrated manufacturing (VCIM) is a realistic concept that can provide the integration requirements for the globally distributed manufacturing resources and it has the potential to satisfy the market requirements of small to medium enterprises. The vision of the VCIM is to improve the efficiency and effectiveness of manufacturing enterprises by seamlessly integrating globally distributed manufacturing resources as much as possible. Meanwhile, intelligent agent technology provides a better means to implement distributed components as integrated application systems. The paper provides a parallel processing multi-agent architecture to support a global integrated manufacturing system in the form of the VCIM. In this architecture, a three-layered structure is proposed to accommodate all the agents no matter where they are located. Multiple Facilitator agents are proposed with similar functionalities to smooth the information flow across the integrated system in a parallel connection manner. In addition, a multi-agent VCIM model that describes the agent identification approaches for VCIM, Java environment implementation approaches and a simulation system to demonstrate the parallel processing multi-agent architecture are also discussed.     

Computation of probabilistic stability measures for a controlled distributed parameter system

Parameter uncertainty can degrade the performance of an otherwise well-designed control system, sometimes leading to system instability. In the context of structural control, performance degradation and instability imply excessive vibration and even structural failure. The ability of a controller to maintain the stability of a system in spite of parameter uncertainty is measured by its robustness, which can be viewed as a probability measure, wherein the joint distribution is of dimension equal to the number of uncertain parameters and the failure hypersurface is defined by the onset of instability in the eigenspace. This observation has led to some recent analyses employing FORM/SORM methods and Monte Carlo simulation.The extension of these concepts to distributed parameter systems is, unfortunately, not immediate. The mere fact that these systems are infinite dimensional precludes the use of much of the machinery available for discrete systems, unless the distributed system is first discretized, which itself introduces error into the analysis, or is represented by an eigenfunction expansion, which requires truncation after some finite number of modes, also a potential source of error. In fact, the system will behave as one with an infinite number of subsystems with highly dependent failure modes in series.In Bergman and Hall, Effect of controller uncertainty on the stability of a distributed parameter system, Structural Safety and Reliability, eds. Schuëller, Shinozuka and Yao, Balkema, Rotterdam, 1993, pp. 210–220, root locus analysis was employed to assess the reliability of the system, requiring the repetitive solution of a transcendental characteristic equation over a range of the parameter under investigation. The loci then provide a mapping from the probability distribution of the random parameter to the probability distribution of the system eigenvalues. This approach was utilized over 30 years ago by Boyce, Random vibration of strings and bars, Proc. of the Fourth US National Congress of Applied Mechanics, Berkeley, 18–21 June, 1962, pp. 77–85, who examined eigenvalue distributions for undamped taut strings and Euler-Bernoulli beams, each subjected to the action of a single point actuator. He demonstrated that, for the case of uncertainty in the actuator gain alone, a simple, closed form mapping leading to the distributions of the eigenvalues of the system could be determined directly from the distribution of the actuator gain, and for uncertainty in the remaining parameters, approximate distributions could be obtained through the application of perturbation methods.In the current paper, the FORM/SORM approach is applied to the taut string problem, where the distributed nature of the system is maintained throughout the analysis. Uncertain parameters, in this case the proportional gain and time delay, are characterized by probability distributions with known mean and variance. Each is transformed to a standard normal variate via Rosenblatt transformations, and the most likely failure point in the parameter space is found using a constrained optimization procedure. The effect of distribution is shown through parameter studies, and verification is provided by Monte Carlo simulation. As expected, time delay is shown to have a pronounced effect upon system robustness.