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841.
以单片机作为控制核心,将现用的手工TIG焊电源改造成全位置自动控制系统,并把管子对接缝分成若干个区间内的峰值电流、基值电流、脉冲频率、占空比及爆接速度,进行程序控制,所进行的全位置管子对接焊工艺试验达到了理想效果,其性能价格比远远优于国外同类性能焊机。 相似文献
842.
843.
基于AHP和模糊评价法的C^3I系统效能评估 总被引:2,自引:1,他引:1
为定量评估C^3I系统的效能,建立了C^3I系统效能的指标体系,并对其中较为重要的指标进行了分析。运用层次分析法(AHP)确定C^3I系统效能评价体系中各指标的权重,使用模糊综合评价法对各模糊指标进行评价,评价结果表明该方法能够比较科学合理地对C^3I系统效能进行评估,从而为评估C^3I系统效能提供了一种论证方法。 相似文献
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845.
This paper presents a simplified method for the reliability- and the integrity-based optimal design of engineering systems and its application to offshore mooring systems. The design of structural systems is transitioning from the conventional methods, which are based on factors of safety, to more advanced methods, which require calculation of the failure probability of the designed system for each project. Using factors of safety to account for the uncertainties in the capacity (strength) or demands can lead to systems with different reliabilities. This is because the number and arrangement of components in each system and the correlation of their responses could be different, which could affect the system reliability. The generic factors of safety that are specified at the component level do not account for such differences. Still, using factors of safety, as a measure of system safety, is preferred by many engineers because of the simplicity in their application. The aim of this paper is to provide a simplified method for design of engineering systems that directly involves the system annual failure probability as a measure of system safety, concerning system strength limit state. In this method, using results of conventional deterministic analysis, the optimality factors for an integrity-based optimal design are used instead of generic safety factors to assure the system safety. The optimality factors, which estimate the necessary change in average component capacities, are computed especially for each component and a target system annual probability of system failure using regression models that estimate the effect of short and long term extreme events on structural response. Because in practice, it is convenient to use the return period as a measure to quantify the likelihood of extreme events, the regression model in this paper is a relationship between the component demands and the annual probability density function corresponding to every return period. This method accounts for the uncertainties in the environmental loads and structural capacities, and identifies the target mean capacity of each component for maximizing its integrity and meeting the reliability requirement. In addition, because various failure modes in a structural system can lead to different consequences (including damage costs), a method is introduced to compute optimality factors for designated failure modes. By calculating the probability of system failure, this method can be used for risk-based decision-making that considers the failure costs and consequences. The proposed method can also be used on existing structures to identify the riskiest components as part of inspection and improvement planning. The proposed method is discussed and illustrated considering offshore mooring systems. However, the method is general and applicable also to other engineering systems. In the case study of this paper, the method is first used to quantify the reliability of a mooring system, then this design is revised to meet the DNV recommended annual probability of failure and for maximizing system integrity as well as for a designated failure mode in which the anchor chains are the first components to fail in the system. 相似文献
846.
由于近几年海事队伍的不断壮大,如今的港口国监督工作时常会由经验较少或相关公约知识不足的新任执法人员担当。鉴于此种情况,文中从新生效公约、船舶软件和船舶硬件三方面入手提出学习建议,使其在较短时间内进入工作角色,并能较专业地开展港口国监督工作。 相似文献
847.
文章主要结合南宁大桥钢一砼连接段的设计特点,从660小石子自密实混凝土浇筑工艺、小石子混凝土配合比设计、工艺性试验以及现场施工准备和浇筑过程控制几个方面介绍了保证钢-砼连接段混凝土施工质量的控制措施。 相似文献
848.
849.
850.
船舶综合电力系统的能量管理控制系统与全数字仿真研究 总被引:1,自引:1,他引:0
近年来,电能逐渐取代传统动力成为船舶的主要推进能源。作为船舶综合电力系统的核心部分之一,船舶综合电力系统的能量管理控制策略设计及其仿真研究得到越来越多的关注。首先,本文从经济性的角度,设计了船舶能量管理系统的控制策略;其次,本文引入储能单元,利用其灵活性强和响应速度快等优点并结合能量管理控制策略减小负荷波动对电网的影响;最后,为验证能量管理控制策略的功能与有效性,建立综合电力系统简化模型。仿真结果表明,采用本文提出的能量管理控制策略可以使机组运行在最佳油耗范围内,并且提出的简化仿真模型可以验证能量管理系统控制策略的功能。 相似文献