Using DSS methods in selecting operations management software

The multitude of software packages available today for production and operations management creates a selection problem. This paper proposes a methodology and a tool to aid decision makers in evaluating and selecting the most appropriate package for their firm. The methodology deals with manufacturing resource planning (MRP) software and outlines two phases: the enumeration of an extensive list of criteria for MRP and the identification of a decision-making method to be used on the basis of these criteria. The analytic hierarchy process (AHP), also selected by the methodology, is applied to an actual case where a software package is selected for an industrial enterprise. Organizational and human implications resulting from the introduction of an MRP package are discussed.     

A new algorithm for wireless sensor network based on NS-2

Considering wireless sensor network characteristics,this paper uses network simulator,version 2 （NS-2） algorithm to improve Ad hoc on-demand distance vector （AODV） routing algorithm,so that it can be applied to wireless sensor networks.After studying AODV routing protocol,a new algorithm called Must is brought up.This paper introduces the background and algorithm theory of Must,and discusses the details about how to implement Must algorithm.At last,using network simulator （NS-2）,the performance of Must is evaluated and compared with that of AODV.Simulation results show that the network using Must algorithm has perfect performance.     

基于ZigBee的水质监测无线传感器网络节点

设计了基于ZigBee的水质监测无线传感器网络系统。采用CC2430作为节点主控芯片,利用Z-Stack协议栈进行软件开发,系统自动采集发送水质数据,并实现了与监控终端之间的通信。试验结果表明:系统能够实时性监测目标水域的水质数据,简单便捷,成本更低。当需要检测的地点比较多时,使用ZigBee技术的优势可以更明显,为广大水域的水质自动监测提供了有效的方法和手段。     

Distributed control architecture for real-time model predictive control for system-level harmonic mitigation in power systems

It can be challenging to design and implement Model Predictive Control (MPC) schemes in systems with fast dynamics. As MPCs often introduce high computational loads, it can be hard to assure real-time properties required by the dynamic system. An understanding of the system’s behavior, to exploit system properties that can benefit real-time implementation is imperative. Moreover, MPC implementations on embedded local devices rarely allows flexibility to changes in model and control philosophy, due to increased complexity and computational loads. A change in control philosophy (run-time) can be quite relevant in power systems that can change from an integrated to a segregated state. This paper proposes a distributed control hierarchy with a real-time MPC implementation, designed as a higher-level control unit, to feed a lower-level control device with references. The higher-level control unit’s objective in this paper is to generate the control reference of an Active Power Filter for system-level harmonic mitigation. In particular, a novel system architecture, which incorporates the higher-level MPC control and handles distribution of control action to low-level controllers, as well as receiving measurements used by the MPC, is proposed to obtain the application’s real-time properties and control flexibility. The higher-level MPC control, which is designed as a distributed control node, can be swapped with another controller (or control philosophy) if the control objective or the dynamic system changes. A standard optimization framework and standard software and hardware technology is used, and the MPC is designed on the basis of repetitive and distributed control, which allows the use of relatively low control update rate. A simulator architecture is implemented with the aim of mimicking a Hardware-In-Loop (HIL) simulator test to evaluate the application’s real-time properties, as well as the application’s resource usage. The results demonstrates that the implementation of the harmonic mitigation application exhibits the real-time requirements of the application with acceptable resource usage.     

MEMS节点化建模及其在集成微系统设计中的应用

为实现MEMS产品的快速设计和性能验证,在借鉴其结构化设计思想即节点分析法的基础上,提出了一种与常规信号流类比不同,适于集成微机电系统快速仿真的等效电路建模思路和方法。首先,对系统及MEMS器件进行功能及结构分解;然后,分别对各基本单元进行节点化建模,并在一定的机电类比规则下将其转换为等效电网络(元件);最后,根据节点变量约束关系,将这些等效网络(元件)逐层重构为器件级和系统级等效电路。结合一类典型MEMS集成系统——梳齿式静电反馈微加速度计的分析实例,对上述方法进行了具体介绍和验证。利用OrCAD等电路仿真器分析、测试了所建立的体现多能域耦合关系的微系统数字化分析原型,结果显示,相对于VHDL-AMS描述法,该模型具有单一域内的更加直观的模型形式和快捷的仿真速度,表明本文提出的方法在复杂MEMS集成系统的分析设计中具有一定的应用价值。     

A stochastic analysis framework for a steel frame structure using wireless sensor system measurements

This paper presents a stochastic analysis framework for estimating the system-level first-passage probability of the structural responses of multi-degree-of-freedom structural systems based on experimentally measured uncertainties. The uncertainties are quantified by comparing the measured structural responses using a wireless sensor system and the predicted responses from an analytical model. The wireless sensor network is designed based on a modular design method, and the experimental program details for the measurement of structural responses are provided using the developed wireless sensor network. This framework employs a Monte Carlo simulation (MCS)-based first-passage probability estimation technique in which a structural dynamic analysis is performed in each simulation realization. The framework is applied to a 16-story steel frame structure, and the first-passage probability of 16 locations and the series system passage probability of the entire system have been estimated. The effect of the dependency between the structural responses is considered, and the improvements that need to be made to the presented framework in the future works are discussed.     

Mobile robotic sensors for perimeter detection and tracking

Mobile robot/sensor networks have emerged as tools for environmental monitoring, search and rescue, exploration and mapping, evaluation of civil infrastructure, and military operations. These networks consist of many sensors each equipped with embedded processors, wireless communication, and motion capabilities. This paper describes a cooperative mobile robot network capable of detecting and tracking a perimeter defined by a certain substance (e.g., a chemical spill) in the environment. Specifically, the contributions of this paper are twofold: (i) a library of simple reactive motion control algorithms and (ii) a coordination mechanism for effectively carrying out perimeter-sensing missions. The decentralized nature of the methodology implemented could potentially allow the network to scale to many sensors and to reconfigure when adding/deleting sensors. Extensive simulation results and experiments verify the validity of the proposed cooperative control scheme.     

Design and implementation of an Internet based effective controlling and monitoring system with wireless fieldbus communications technologies for process automation--an experimental study

The network requirements of control systems in industrial applications increase day by day. The Internet based control system and various fieldbus systems have been designed in order to meet these requirements. This paper describes an Internet based control system with wireless fieldbus communication designed for distributed processes. The system was implemented as an experimental setup in a laboratory. In industrial facilities, the process control layer and the distance connection of the distributed control devices in the lowest levels of the industrial production environment are provided with fieldbus networks. In this paper, the Internet based control system that will be able to meet the system requirements with a new-generation communication structure, which is called wired/wireless hybrid system, has been designed on field level and carried out to cover all sectors of distributed automation, from process control, to distributed input/output (I/O). The system has been accomplished by hardware structure with a programmable logic controller (PLC), a communication processor (CP) module, two industrial wireless modules and a distributed I/O module, Motor Protection Package (MPP) and software structure with WinCC flexible program used for the screen of Scada (Supervisory Control And Data Acquisition), SIMATIC MANAGER package program ("STEP7") used for the hardware and network configuration and also for downloading control program to PLC.     

履带式工程车模拟器数据采集与传输的设计与实现

设计了以MSP430单片机为核心的履带式工程车模拟器的数据采集与传输装置,在阐述系统原理的基础上,设计了硬件结构,开发了系统软件,实现了对模拟器的挡位情况、油门大小等状态参数实时采集并与上位机进行实时通信的功能.同时,系统能根据操纵者操纵模拟器时动作的规范程度自动作出相关控制反应,具有可靠性高、成本低、灵活性好等特点.     

Web-based CBR (case-based reasoning) as a tool with the application to tooling selection

Over the past few years, manufacturing companies have had to deal with an increasing demand for feature-rich products at low costs. The pressures exerted on their existing manufacturing processes have lead manufacturers to investigate internet-based solutions, in order to cope with growing competition. The decentralisation phenomenon also came up as a reason to implement networked-application, which has been the starting point for internet/intranet–based systems. Today, the availability of powerful and low cost 3D tools, database backend systems, along with web-based technologies, provides interesting opportunities to the manufacturing community, with solutions directly implementable at the core of their businesses and organisations. In this paper a web-based engineering approach is presented to developing a design support system using case-based reasoning (CBR) technology for helping in the decision-making process when choosing cutting tools. The system aims to provide on-line intelligent support for determining the most suitable configuration for turning operations, based on initial parameters and requirements for the cutting operation. The system also features a user-driven 3D turning simulator which allows testing the chosen insert for several turning operations. The system aims to be a useful e-manufacturing tool being able to quickly and responsively provide tooling data in a highly interactive way.     

A Conceptual Approach to Integrate Design and Control for the Epoxy Dispensing Process

Performance improvement of manufacturing systems in the semiconductor industry involves interdisciplinary expertise, such as physical modeling, mechanical design, electrical control, and even material science. Integration of these different disciplines is a challenging problem in the semiconductor industry. The paper presents a conceptual approach to integrate design and control methodology for complex processes with specific application to an epoxy-dispensing control system – a critical equipment in the semiconductor packaging process. This methodology includes three hierarchical levels: process design (system-level and component-level), multivariable control and the statistics-based supervision. This paper deals with conceptual design at system-level by integrating an approximate model with an axiomatic approach, and briefly introduces approaches at other levels. In the conceptual design at system level, the primitive model of the system is sufficient to show some basic properties of the process, by which the axiomatic design can be easily integrated to evaluate the system design and suggest an optimal system configuration with invariant properties to internal variations. Under minimal internal variation, the multivariable control that is intended to suppress external variations can be approximately constructed by a set of independent controllers. Statistics-based supervision will provide suitable setpoints for the multivariable control so as to maintain good performance in the dynamic environment.     

智慧城市感知消防系统的软件平台设计

主要介绍智慧城市感知消防系统的软件平台设计,提出了采用RS-485通信和WSN(无线传感器网络)网络的ZigBee技术的双备份通信技术,使系统模型同时具有有线和无线双备份组网的能力,系统通信具有一定冗余性,增加了通信的可靠性。最后,采用实验并搭建仿真模型的方法,验证所提出的技术方案的可行性,为未来智能的感知消防系统设计提供了一个技术参考。     

Dynamic behavior analysis of drill-threading process when machining AISI Al-Si-Cu4 alloy

Conventional threading operations involve two distinct machining processes: drilling and threading. Therefore, it is time consuming for the tools must be changed and the workpiece has to be moved to another machine. This paper presents an analysis of the combined process (drilling followed by threading) using a single tool for both operations: the tap-milling tool. Before presenting the methodology used to evaluate this hybrid tool, the ODS (operating deflection shapes) basics is shortly described. ODS and finite element modeling (FEM) were used during this research to optimize the process aiming to achieve higher stable machining conditions and increasing the tool life. Both methods allowed the determination of the natural frequencies and displacements of the machining center and optimize the workpiece fixture system. The results showed that there is an excellent correlation between the dynamic stability of the machining center-tool holder and the tool life, avoiding a tool premature catastrophic failure. Nevertheless, evidence showed that the tool is very sensitive to work conditions. Undoubtedly, the use of ODS and FEM eliminate empiric decisions concerning the optimization of machining conditions and increase drastically the tool life. After the ODS and FEM studies, it was possible to optimize the process and work material fixture system and machine more than 30,000 threaded holes without reaching the tool life limit and catastrophic fail.     

蓝牙技术在野外现场维修支援中的应用研究

介绍了一种基于蓝牙无线网络技术支持的野外现场维修支援系统总体结构、通信部分软硬件结构和安全管理技术。     

基于FPAA的自修复智能无线传感器节点

针对无线传感器网络自身的可靠性和维护问题,提出了一种基于FPAA(field programmable analog arrays)的自修复智能无线传感器节点的实现方法.该方法以FPAA为核心构成传感器的主要信号调理电路,节点设计有硬件故障自诊断功能,在节点部分硬件模块发生故障的情况下,可修复相应故障,确保节点在无人职守及野外应用时的可靠性,避免节点的直接丢弃.重点介绍了自修复节点的实现方法、软硬件研发并对节点进行了自修复实验研究,分析了自修复节点的功耗及可工作时间,节点能够在2节具有1700 mAh的AA电池的供电下工作半年时间.     

近距光信息的色度加密方法传送研究

对一种可用于楼宇之间或校园环境的近距无线光信息加密传送的方案进行了简要讨论。设计的系统中采用可见光作为工作波长,液晶屏为调制器,凸透镜系统为发射、接收光学天线。提出简易色度矢量替代型仿量子密钥的设计方法并对其性能进行了分析。然后在不同的传输条件下,不断进行室外测试试验,从而验证系统模型的可靠性。实验表明,该系统可实现短距离的加密光通信并可作为模仿量子通信的示教工具。     

Dynamic wireless passive strain measurement in CNC turning using surface acoustic wave sensors

Wireless, passive and dynamic surface acoustic wave (SAW) strain sensors are especially advantageous in applications with harsh environments where complex force measurements are required. High frequency multiple axis force measurement during machining processes typically requires state-of-the-art piezoelectric dynamometer technologies. Integrating dynamometers and their associated measurement chains into the machining environment typically requires significant modification to the machine structure. In this paper, SAW sensors were developed for process monitoring operations. Single-axis continuous and interrupted cutting investigations were carried out using the SAW technology installed on cutting tool holders demonstrating high dynamic bandwidth strain measurement. SAW dual-axis oblique cutting measurements were carried out where four SAW sensors were set up as two differential pairs each measuring a single axis of applied force. Improvements in sensitivity and cross-talk compensation has been realised. High-frequency wireless passive realtime process signals are presented from a passive wireless SAW force measurement system successfully integrated into an LT15 Okuma machining centre. The paper aims to present wireless passive SAW technology as a potentially platform changing approach for process and tool condition monitoring applications in the future.     

A queueing model for a two-stage stochastic manufacturing system with overlapping operations

This paper presents analytical expressions for estimating average process batch flow times through a stochastic manufacturing system with overlapping operations. It is shown that the traditional queueing methodology cannot be directly applied to this setting, as the use of the overlapping operations principle causes the arrival process of sublots at the second stage to be a non-renewal process. An embedded queueing model is then proposed, which provides a tool to estimate the flow time reductions caused by the use of overlapping operations. Moreover, we provide expressions to estimate the production disruptions occurring at the second stage. The results of our research confirm the general intuition that the overlapping operations principle leads to less congestion, and hence a smoother flow of work through the system. On the other hand however, lot splitting inevitably requires more material handling on the shop floor. The expressions provided in this paper allow the quantification of the trade-off between these two effects, e.g., by gauging them within the scope of a cost model.     

基于无线传感器网络的瓦斯监测系统

针对无线传感器网络技术和瓦斯监测的发展现状,提出了基于无线传感器网络的瓦斯监测系统的网络构建方案,对网络中的瓦斯传感器节点的硬件结构进行了设计,并对系统的软件进行了分析和设计。无线传感器网络技术在瓦斯监测方面拥有广阔的应用前景。