IEEE 1588精密时钟同步协议2.0版本浅析

在分布式测控系统中,各分布式设备、独立的智能传感器、作动器与系统之间的时钟同步是系统测控数据有效性的关键。IEEE 1588精密时钟同步协议有效地解决了分布式测控系统时间同步问题,也是新测试系统总线标准LXI的核心技术之一。首先介绍了IEEE 1588时钟同步的基本原理,之后主要针对最新发布的IEEE 1588 2.0版本所采用的新技术、新方法进行了分析,为进一步研究打下基础。     

从北京2008年奥运体育图标设计看设计资源管理

设计资源是"资源"内涵中的一种。从艺术设计和管理的角度而言,它是构成设计活动最基本的要素,指的是一切为设计活动所利用,并由此产生的经济效益和社会效益的事物。奥运体育图标设计是奥运人文精神、体育精神和民族精神的集中体现,它的意义已超越了人文价值本身,上升到了国家整体战略的高度。     

Algorithms to Separate $\{0,\frac{1}{2}\}$ -Chvátal-Gomory Cuts

Chvátal-Gomory cuts are among the most well-known classes of cutting planes for general integer linear programs (ILPs). In case the constraint multipliers are either 0 or , such cuts are known as -cuts. It has been proven by Caprara and Fischetti (Math. Program. 74:221–235, 1996) that separation of -cuts is -hard. In this paper, we study ways to separate -cuts effectively in practice. We propose a range of preprocessing rules to reduce the size of the separation problem. The core of the preprocessing builds a Gaussian elimination-like procedure. To separate the most violated -cut, we formulate the (reduced) problem as integer linear program. Some simple heuristic separation routines complete the algorithmic framework. Computational experiments on benchmark instances show that the combination of preprocessing with exact and/or heuristic separation is a very vital idea to generate strong generic cutting planes for integer linear programs and to reduce the overall computation times of state-of-the-art ILP-solvers.     

Whole-body vibration exposure experienced by motorcycle riders – An evaluation according to ISO 2631-1 and ISO 2631-5 standards

Riders of twelve motorcycles, comprising 6 full-scale motorbikes and 6 motor-scooters, and 5 sedan vehicles, performed test runs on a 20.6 km paved road composed of 5 km, 5 km, and 10.6 km of rural, provincial and urban routes, respectively. Each test run of motorcycle was separately performed under speed limits of 55 km/h and 40 km/h. Tri-axial accelerations of whole-body vibration (WBV) were obtained by using a seat pad and a portable data logger, and the driver's view was videotaped with a portable media recorder. Root mean square (RMS) acceleration, 8-h estimated vibration dose value (VDV₍₈₎) and 8-h estimated daily dose of static compression dose (S_ed) were determined from the collected data in accordance with ISO 2631-1 and ISO 2631-5 standards. Experimental results indicate that the WBV values of the sedan vehicle drivers have low RMS, VDV₍₈₎ and S_ed values (RMS 0.27–0.32 m/s²; VDV₍₈₎ 6.3–8.3 m/s^1.75; S_ed 0.21–0.26 MPa). However, over 90% of the motorcycle riders had VDV₍₈₎ (mean 23.5 m/s^1.75) exceeding the upper boundary of health guidance caution zone (17 m/s^1.75) recommended by ISO 2631-1, or had S_ed (mean 1.17 MPa) exceeding the value associated with a high probability of adverse health effects (0.8 MPa) recommended by ISO 2631-5. Over 50% of the motorcycle riders reached these boundary values for VDV and S_e in less than 2 h. The WBV exposure levels of the full-scale motorbikes riders and motor-scooter riders were not significantly different. However, the RMS and VDV₍₈₎ values of motorcycle riders indicate significant roadway effect (p < 0.001), while their S_ed values indicate significant speed limit effect (p < 0.05). This study concludes that the WBV exposure levels of common motorcycle riders are distinctively higher than those of sedans, even on a regular paved road. The impact on health of WBV exposure in motorcycle riders should be carefully addressed with reference to ISO 2631-1 and ISO 2631-5.

Relevance to industry

This study compares the predicted health risks of motorcycle riders according to ISO 2631-1 and ISO 2631-5 standards. Experimental data suggest that the vibration dose value of ISO 2631-1 and daily dose of equivalent static compression stress of ISO 2631-5 have roughly equivalent boundaries for probable health effects.     

基于marble的三维可视化技术研究

随着三维可视化技术的高速发展和广泛应用,很多应用工程领域需要三维地理信息系统显示空间数据。据此介绍了marble的特点和应用方式,详细论述使用VS2008和Qt构建marble源码的基本过程。应用实例表明,基于marble的空间数据三维图形显示真实、形象、直观。     

Standard process monitoring and traceability programming in collaborative CAD/CAM/CNC manufacturing scenarios

The paper focuses on collaborative STEP-based CAD/CAM/CNC supply chains to program and automate machining process data monitoring and traceability activities. A traceability interface (traceability nc_functions) is defined for the new CNC programming standard ISO STEP-NC. CAM systems will be able to program monitoring and data access activities by inserting traceability nc_function calls in CNC programs. On the shop floor, controllers will automatically interpret these nc_functions to access process data while machining and will relate data records with the corresponding machining operations in a STEP-NC part program. With both types of information—process data and standard machining program (STEP-NC part program)—spread and technologically heterogeneous engineering systems will have full knowledge about what has happened in production. Traceability data access automation will assure data reliability. The paper describes a traceability scenario where standards such as MTConnect and ISA-95 support, rather than interfere with, the STEP-NC traceability proposal.     

UML在分布式系统中的应用与研究

ＵＭＬ（Ｕｎｉｆｉｅｄ　 Ｍｏｄｅｌｉｎｇ 　Ｌａｎｇｕａｇｅ）是一种标准的、功能强大的建模语言。ＩＳＯ ＲＭ－ＯＤＰ（ＩＳＯ开放分布式处理参考模型）为开放、灵活的分布式系统提供了主框架。文章提出了一种用ＵＭＬ为ＯＤＰ系统建模的方法,它以ＯＤＰ的概念和ＵＭＬ的符号为基础。     

军用软件开发过程的质量管理体系研究

军用软件系统的开发在我军信息化建设中占据至关重要的地位。大型武器装备系统的军用软件开发,成本高、风险大、周期长,参与单位及人员众多,如何能够确保大型军用软件的质量,增强武器装备性能,成为亟待解决的课题。本文将质量管理体系引入军用软件开发过程之中,通过强化过程控制,来确保大型军用软件的开发质量,对军队信息化建设,特别是软件系统的开发起到指导和借鉴作用。     

多任务密码服务系统设计与实现

在当前的安全体系架构中,大多数密码服务均由密码服务中间件保障,其共同特点是功能性强但安全性不高。针对上述问题指出了一种解决思路,将密码运行与密钥管理下移至安全的硬件设备内。ISO／IEC7816标准是当前智能卡的国际标准,其中7816-8描述与安全相关的行业间命令。文章在结构上改进一个以ISO／IEC7816-8为设计蓝本的密码服务系统,加入一个中间层,称之为运行环境,设计了运行环境的结构;设计完善了管理安全环境命令;制定了密码服务多任务运行调度策略,实现了任务间的动态切换,得到了一个多任务密码服务系统。     

引入ISO9000标准提升环卫作业企业管理质量

根据ISO9001质量管理体系要求,结合常州市环卫事业发展要求,阐释引入ISO9001质量管理体系并运用于环卫作业企业管理质量控制中的必要性和可行性,并提出环卫作业企业质量管理策划、控制、监测和改进的方法。