三维前方交会在网架屋面质量监测中的应用

重点探讨了三维前方交会法的原理及其在金属网架结构屋面施工的质量监测方法,保证施工质量,达到设计要求,为今后的安全运营提供了可靠的依据。同时为大型无支撑建筑屋面的变形监测提供了一种测量监测依据。     

八叉树构模法在重磁场正演方面的应用

本文采用三维来表达地质现象即三维地质构模,对三维空间的数据模型进行研究,对八叉树构模方法和重磁场正演计算进行了详细的介绍,并把八叉树对三维地质体构模和重磁场正演相结合开发了三维重磁场正演可视化交互系统.此系统的建立基本上实现了重磁场的实时正演计算功能,为地学工作者提供了一个直观、形象的三维解释平台.     

从政治动员到市场运作——嵖岈山乡镇企业20世纪50年代末和80年代后发展模式比较

河南省嵖岈山乡曾经是20世纪50年代末"大跃进"时期人民公社化运动的典型,在人民公社大办工业时也是一马当先,办了一大批企业。但这些企业是当时政治运动的产物,是通过政治动员的方式建立起来的,有些本来就是"大跃进"浮夸出来子乌虚有的,当然,随着"大跃进"的灾难性后果而不了了之,造成了人力、物力的极大浪费。20世纪80年中期代以来,随着农村经济体制改革的实施,嵖岈山乡的企业发展起来。这一时期的企业发展是以本地资源为基础,以市场需求为导向,以发展地方经济为目的,遵循经济发展规律。现在,这个乡的企业产值已经占经济总产值的40%。     

《全国农业发展纲要》与农业"大跃进"的发动

作为我国"社会主义时期第一个以发展农业为主要内容的经济发展战略"〔1〕,《1956年到1967年全国农业发展纲要》历经五个发展阶段,见证了我国农业生产由健康、稳定、高速的发展逐步走向急躁冒进的过程。也正是这个发展纲要,继承了之前存在于建设工作中的左倾冒进思想影响,并在随后指导实际经济建设过程中将这种影响不断扩大,最终在实际上成为了农业"大跃进"运动的总纲领,拉开了农业"大跃进"的序幕。     

决策者失误与信息失真——关于"大跃进"时期的信息状况及其失真原因

大跃进时期的信息传递呈现出从真假并存到以假为主的发展态势。虚假信息的基本表现形式为虚报浮夸与造假报假,其主要特征为普遍性和易识性。造成虚假信息泛滥的主要动因有:对形势的看法与估计被上升至阶级斗争与政治斗争的高度;憧憬和激情代替了科学与理智;个人专断与崇拜取代了集体决策与领导以及工作方法上的重大失误等。是决策者的失误造成了信息失真,而不是信息失真导致了决策失误。     

Dealing with forward and backward jumps in workflow management systems

Zusammenfassung. Workflow management systems (WfMS) offer a promising technology for the realization of process-centered application systems. A deficiency of existing WfMS is their inadequate support for dealing with exceptional deviations from the standard procedure. In the ADEPT project, therefore, we have developed advanced concepts for workflow modeling and execution, which aim at the increase of flexibility in WfMS. On the one hand we allow workflow designers to model exceptional execution paths already at buildtime provided that these deviations are known in advance. On the other hand authorized users may dynamically deviate from the pre-modeled workflow at runtime as well in order to deal with unforeseen events. In this paper, we focus on forward and backward jumps needed in this context. We describe sophisticated modeling concepts for capturing deviations in workflow models already at buildtime, and we show how forward and backward jumps (of different semantics) can be correctly applied in an ad-hoc manner during runtime as well. We work out basic requirements, facilities, and limitations arising in this context. Our experiences with applications from different domains have shown that the developed concepts will form a key part of process flexibility in process-centered information systems.Received: 6 October 2002, Accepted: 8 January 2003, This paper is a revised and extended version of [40]. The described work was partially performed in the research project Scalability in Adaptive Workflow Management Systems funded by the Deutsche Forschungsgemeinschaft (DFG).     

一种抗DoS攻击的轻量级密钥交换协议

在IPSec大规模部署应用下,分析了IKEv2和JFK两种现有协议安全及性能缺陷,提出了一种轻量级密钥交换协议LKE,该协议能有效减少报文交互数量,降低计算资源开销。通过经典Puzzle机制和两轮异步Diffie-Hellman交换,解决了抗DoS攻击与完美前向安全特性难以共存的问题。仿真结果表明,LKE对低带宽通信环境具有较强的适应性,在低于384kbps的无线链路条件下,LKE协议的收敛时间相比IKEv2和JFK分别减少了20%和10%。     

Three dimensional musculoskeletal modelling of the seated biceps curl resistance training exercise

The aim of this study was to evaluate the benefits and limitations of using three dimensional (3D) musculoskeletal modelling (LifeModeler?) in assessing the safety and efficacy of exercising on a seated biceps curl resistance training machine. Three anthropometric cases were studied, representing a 5^th percentile female, 50^th percentile and 95^th percentile male. Results indicated that the LifeModeler? default model was not adequate to solve the forward dynamics simulations. Therefore adjustments had to be made to the default model to successfully complete the forward dynamics simulations. The software was able to sufficiently highlight the shortcomings of the biceps curl machine's engineered adjustability in relation to the anthropometric dimensions of the studied cases, as the 5^th percentile female could not be accommodated suitably on the machine. High lumbar spine anterior/posterior shear forces for all anthropometric cases and maximum muscle tensions for the female and 50^th percentile male indicate that the seated biceps curl exercise may pose risks for injuries. To conclude, it appears that 3D musculoskeletal modelling can be used to evaluate resistance training equipment such as the seated biceps curl machine. However the limitations as indicated by this study must be taken into consideration, especially when using the default LifeModeler? model.     

Forward and backward models for fault diagnosis based on parallel genetic algorithms

In this paper, a mathematical model consisting of forward and backward models is built on parallel genetic algorithms （PGAs） for fault diagnosis in a transmission power system. A new method to reduce the scale of fault sections is developed in the forward model and the message passing interface （MPI） approach is chosen to parallel the genetic algorithms by global single-population master-slave method （GPGAs）. The proposed approach is applied to a sample system consisting of 28 sections, 84 protective relays and 40 circuit breakers. Simulation results show that the new model based on GPGAs can achieve very fast computation in online applications of large-scale power systems.     

“大跃进”时期生态环境问题论析——以河北省为例

"大跃进"运动中,河北省盲目修建的众多水库潜伏下一系列环境问题。过量开采地下水,过度深翻土地,使农业环境趋于恶化;捕杀麻雀导致生物链在一定程度上断裂;"大炼钢铁"运动造成矿产资源的滥采滥挖,林木资源的滥砍滥伐;不合理的工业布局埋下污染隐患。"左"的指导方针不仅给经济发展带来了严重危害,也恶化了生态环境。重近利,失远谋;重生产开发,轻环境保护,这种短视行为带来长期性、累积性的严重后果。