Long Distance Wireless Networking for Site - Office Data Communications

Effective data communications between the project site and decision making office can be critical for the success of a construction project. It allows convenient access to centrally stored information and allows centrally located decision makers to remotely monitor the site and collect data in real-time. However, high bandwidth, flexible data communication networks, such as wired local area networks, can often be time-consuming and costly to deploy for such purposes especially when project sites (dams, highways, etc.) are located in rural, undeveloped areas where networking infrastructure is not available. In such construction sites, wireless networking could reliably link the construction site and the decision-making office. This paper presents a case study on long-distance, site – office wireless data communications. The purpose was to investigate the capability of wireless technology in exchanging construction data in a fast and efficient manner and in allowing site personnel to interact and share knowledge and data with the office staff. This study took place at the University of Michigan’s campus where performance, reliability, and cost/benefit tests were performed. The indoor and outdoor tests performed demonstrated the suitability of this technology for office-site data communications and exposed the need for more research to further improve the reliability and data handling of this technology.

Accelerator-induced transients in Accelerator Driven Subcritical Reactors

Achieving higher particles energies and beam powers have long been the main focus of research in accelerator technology. Since Accelerator Driven Subcritical Reactors (ADSRs) have become the subject of increasing interest, accelerator reliability and modes of operation have become important matters that require further research and development in order to accommodate the engineering and economic needs of ADSRs. This paper focuses on neutronic and thermo-mechanical analyses of accelerator-induced transients in an ADSR. Such transients fall into three main categories: beam interruptions (trips), pulsed-beam operation, and beam overpower. The concept of a multiple-target ADSR is shown to increase system reliability and to mitigate the negative effects of beam interruptions, such as thermal cyclic fatigue in the fuel cladding and the huge financial cost of total power loss. This work also demonstrates the effectiveness of the temperature-to-reactivity feedback mechanisms in ADSRs. A comparison of shutdown mechanisms using control rods and beam cut-off highlights the intrinsic safety features of ADSRs. It is evident that the presence of control rods is crucial in an industrial-scale ADSR. This paper also proposes a method to monitor core reactivity online using the repetitive pattern of beam current fluctuations in a pulsed-beam operation mode. Results were produced using PTS-ADS, a computer code developed specifically to study the dynamic neutronic and thermal responses to beam transients in subcritical reactor systems. © 2012 Elsevier B.V.

Design of brushless doubly-fed machines based: On magnetic circuit modeling

This paper proposes a magnetic circuit model (MCM) for the design of a brushless doubly-fed machine (BDFM). The BDFM possesses advantages in terms of high reliability and reduced gearbox stages, and it requires a fractionally-rated power converter. This makes it suitable for utilization in offshore wind turbines. It is difficult for conventional design methods to calculate the flux in the stator because the two sets of stator windings, which have different pole number, form a complex flux pattern which is not easily determined using common analytical approaches. However, it is advantageous to predict the flux density in the teeth and air-gap at the initial design stage for sizing purposes without recourse finite element analysis. Therefore a magnetic circuit model is developed in this paper to calculate the flux density. A BDFM is used as a case study with FEA validation. © 1965-2012 IEEE.

An experimental study on engine dynamics model based in-cylinder pressure estimation

The information provided by the in-cylinder pressure signal is of great importance for modern engine management systems. The obtained information is implemented to improve the control and diagnostics of the combustion process in order to meet the stringent emission regulations and to improve vehicle reliability and drivability. The work presented in this paper covers the experimental study and proposes a comprehensive and practical solution for the estimation of the in-cylinder pressure from the crankshaft speed fluctuation. Also, the paper emphasizes the feasibility and practicality aspects of the estimation techniques, for the real-time online application. In this study an engine dynamics model based estimation method is proposed. A discrete-time transformed form of a rigid-body crankshaft dynamics model is constructed based on the kinetic energy theorem, as the basis expression for total torque estimation. The major difficulties, including load torque estimation and separation of pressure profile from adjacent-firing cylinders, are addressed in this work and solutions to each problem are given respectively. The experimental results conducted on a multi-cylinder diesel engine have shown that the proposed method successfully estimate a more accurate cylinder pressure over a wider range of crankshaft angles. Copyright © 2012 SAE International.

Computational engineering design for micro-scale combustion devices: A thermally improved configuration

A multi-objective design optimisation study has been carried out with the objectives to improve the overall efficiency of the device and to reduce the fuel consumption for the proposed micro-scale combustor design configuration. In a previous study we identified the topology of the combustion chamber that produced improved behaviour of the device in terms of the above design criteria. We now extend our design approach, and we propose a new configuration by the addition of a micro-cooling channel that will improve the thermal behaviour of the design as previously suggested in literature. Our initial numerical results revealed an improvement of 2.6% in the combustion efficiency when we applied the micro-cooling channel to an optimum design configuration we identified from our earlier multi-objective optimisation study, and under the same operating conditions. The computational modelling of the combustion process is implemented in the commercial computational fluid dynamics package ANSYS-CFX using Finite Rate Chemistry and a single step hydrogen-air reaction. With this model we try to balance good accuracy of the combustion solution and at the same time practicality within the context of an optimisation process. The whole design system comprises also the ANSYS-ICEM CFD package for the automatic geometry and mesh generation and the Multi-Objective Tabu Search algorithm for the design space exploration. We model the design problem with 5 geometrical parameters and 3 operational parameters subject to 5 design constraints that secure practicality and feasibility of the new optimum design configurations. The final results demonstrate the reliability and efficiency of the developed computational design system and most importantly we assess the practicality and manufacturability of the revealed optimum design configurations of micro-combustor devices. Copyright © 2013 by ASME.

Layered Architecture for Secure E-Commerce Applications

We present a layered architecture for secure e-commerce applications and protocols with fully automated dispute-resolution process, robust to communication failures and malicious faults. Our design is modular, with precise yet general-purpose interfaces and functionalities, and allows usage as an underlying secure service to different e-commerce, e-banking and other distributed systems. The interfaces support diverse, flexible and extensible payment scenarios and instruments, including direct buyer-seller payments as well as (the more common) indirect payments via payment service providers (e.g. banks). Our design is practical, efficient, and ensures reliability and security under realistic failure and delay conditions.

高可用性工业以太网技术的研究与实现

针对现场总线控制系统对高可靠性和稳定性的要求会限制工业以太网的应用问题,在原有网络的基础上添加一个并行的冗余链路,以增强通信的可用性,减小通信链路故障对系统运行的影响。结合EPA通信协议栈,设计并行网络冗余解决方案,包括协议栈结构、帧结构和通信过程。给出该方案的性能分析。

T-Kernel在Blackfin处理器上的移植分析

T-Kernel是日本T-Engine组织推出的开源免费的嵌入式实时操作系统(RTOS),以其强实时小体积内核著称。本文针对T-Kernel在Blackfin处理器(BF533)上的移植过程进行了分析,给出了中断管理,任务切换和系统调用入口的实现方法,并进行了稳定性和实时性测试,保证了移植系统的性能。

基于C8051的运动控制卡研制和应用

本文针对排爆机器人手臂多关节联动控制的需要,开发了一种具有高集成度的基于C8051单片机和CAN总线的运动控制卡。介绍了运动控制卡的原理及实施方案,同时给出了运动控制卡在机器人平台的应用实例。在排爆机器人平台上的应用表明该运动控制卡具有较高的精度及很好的可靠性和实时性。

基于多微处理器的智能超声探测系统

设计了一种基于多微处理器的智能超声探测系统。该系统采用由上位工作模式控制单元和下位智能超声传感器阵列组成的分布式结构。每个超声传感器均由独立的微处理器控制,并完成实时数据处理、抗干扰处理、故障报警以及数据通信等功能。上位控制单元根据移动机器人的运动状态采用不同的控制策略,使下位传感器阵列分组并行工作,提高了探测系统的实时性;下位传感器采用"阈值比较法"、"改进型递推均值滤波"算法和模糊信息处理技术,提高了探测系统的准确性、可靠性。将该探测系统安装于RIRA-II移动机器人上,进行了基于主动视觉和超声信息的运动目标跟踪实验,实验表明超声探测系统运行可靠、稳定。

软件设计模式在移动机器人控制系统中的应用

介绍了软件设计模式的基本概念和主要特点。分析了已有移动机器人平台控制系统的功能需求,阐述了总线模式的结构及实现机制。运用总线模式设计了机器人控制系统,并在QNX平台下使用标准C++完成了该控制系统的实现。设计实现的控制系统结构合理,具有很强的实时性、可靠性和可扩展性。

基于Internet的力反馈技术研究

论述了基于Internet的力反馈技术及其相关技术的发展和研究意义 ,综合机器人遥操作控制领域的理论方法 ,结合多媒体技术的最新发展 ,构建了一种基于事件的系统结构及其设计方法 .基于该方法 ,分析了系统的可靠性、稳定性及力媒体传输的透明性 ,并设计了一个基于Internet的力反馈技术的系统实例

深海机器人推进电机系统的混沌控制

深海机器人推进电机系统中出现的混沌现象,直接影响深海机器人稳定性、可靠性和安全性.采用自适应控制技术对其混沌行为加以控制,对该方法的可行性和有效性进行了证明.设计和构造了易于工程实施的混沌控制器,用于深海机器人推进电机系统混沌控制.仿真实验表明,推进电机系统在自适应控制器的作用下可迅速脱离混沌状态,并进入持续稳定状态,控制效果明显.可以为深海机器人推进电机系统中可能出现的混沌运行行为提供控制策略和抑制预案,有利于混沌控制嵌入软件的开发,确保深海机器人稳定、可靠和安全地运行,具有一定的实用价值.

基于信道估计的RS纠错编码改进算法的设计与实现

提出了一种基于信道估计的RS纠错编码改进算法,该算法可以自适应地根据外界条件和环境对传输信道的干扰变化实时地调节编码系统的数据冗余量。仿真与完整的分析结果证实了该改进算法有效地改善了RS编码算法的传输效率;并且通过实际应用表明:良好的性能,高容错性适应于该通信系统的多种传输信道,具有很强的实用性。

AUV内部通讯总线设计

设计了基于CAN协议的AUV内部通讯总线系统 .系统通过协议转换器的模块化、可配置性设计满足AUV系统对其内部通讯总线的开放性要求 .协议转换器内部的容错处理能力以及紧急事件处理节点的设计为增强AUV系统的可靠性和容错能力、为避免AUV在深海工作环境下丢失增加有力的保障措施