定制化零件集成设计的几何特征与可制造模型构建

为解决针对航天运载工具普遍存在的定制化零件难于制造问题,文中提出在设计阶段既考虑其可制造性的集成设计思路.讨论了一类定制化零部件的几何特征和描述方式,依照其特点对其特征参数进行了定义;构建了考虑制造设备信息的可制造性评估模型,包括制造资源模型、制造过程模型、特征关系模型和制造对象模型.通过具体实例给出了集成设计过程的可制造模型部分结果.结果表明:模型兼顾了设计和制造信息,设计效率提高,制造成本降低.     

基于冗余度分析的海上风电场可靠性提高方法

讨论了基于冗余度分析的海上风电场内部电能收集系统和传输系统可靠性提高方法.定义了风电场低压/中压网络与高压传输系统的冗余度.在同时考虑可靠性和经济性的前提下,提出了系统进行风电场冗余设计的方法.采用大型海上风电场设计实例对所提方法进行了验证,得到了最优冗余设计结果.该方法对于提高具有复杂拓扑的大型海上风电场电能收集和传榆系统的可靠性具有一定应用优势.     

Impact of communication medium on task performance and satisfaction: an examination of media-richness theory

Among several theories to explain how communications media affect task performance, media-richness theory is often cited. It proposes that task performance will be improved when task-information processing requirements are matched to a medium's ability to convey information richness.The objective of the work reported here was to examine media-richness theory using a laboratory experiment. The investigation focused on the effect of four different communication media (text, audio, video, and face-to-face) on task performance and satisfaction of both, intellective and negotiation tasks. For the negotiation task, a social psychological factor, consonancy, was used to examine the effect of interaction on media and performance.Overall, the study did not support media-richness theory. There were no task–medium interaction effects on either decision quality or decision time. Decision quality was the same for both the tasks. Audio was the most efficient medium, but not necessarily the most satisfying. This study did not support the combined theory of media richness and social psychology for the negotiation task. There was no significant media-by-consonancy interaction in the negotiation payoff.     

Vibratory weld conditioning — the effect of rigid body motion vibration during welding

Previous studies suggested that the state of residual stress in a weld may be modified by vibration during and after the welding process. In this study, the effect of rigid body motion vibration on welding residual stresses was investigated. The specimens were welded while they were being vibrated in a rigid body motion mode. The specimens were vibrated using two different frequencies (50 Hz and 500 Hz). At the lower frequency vibration (50 Hz), small changes in the residual stresses were found, with no particular trend. At the high frequency vibration, no significant reductions in the residual stresses were observed in the longitudinal stresses or in the transverse direction. Some initial results are presented also regarding flexural vibration effects.     

Dyadic interactions at the microcomputer interface: a case study in computer assisted learning

Abstract A case study in which dyads of subjects (both a pupil-pupil and a teacher-pupil dyad) use a microcomputer computer assisted learning (CAL) program is discussed. We argue that an approach involving the videotaping of pupils' interactions around the computer, microanalysing the resulting dialogue, and relating the results from the dialogue analysis to learning outcomes is a potentially very powerful method for evaluating the educational efficacy of CAL software. The present case study describes a technique for collecting appropriate data, indicates the richness of such dialogue data and illustrates some of the hidden problems in CAL program use which other evaluation methods are unlikely to expose.