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961.
介绍自密封阀的密封原理及其在氨汽提尿素装置中的应用,对其长期运行中出现的泄漏及泄漏原因进行分析,根据不同的泄漏方式分别提出了现场维修的方法. 相似文献
962.
In a large-scale locality-driven network such as in modular robotics and wireless sensor networks, knowing the state of a local area is sometimes necessary due to either interactions being local and driven by neighborhood proximity or the users being interested in the state of a certain region. We define locality-aware predicates (LAP) that aim at detecting a predicate within a specified area. We model the area of interest as the set of processes that are within a breadth-first search tree (BFST) of height k rooted at the initiator process. Although a locality-aware predicate specifies a predicate only within a local area, observing the area consistently requires considering the entire system in a consistent manner. This raises the challenge of making the complexities of the corresponding predicate detection algorithms scale-free, i.e., independent of the size of the system. Since all existing algorithms for getting a consistent view of the system require either a global snapshot of the entire system or vector clocks of the size of the system, a new solution is needed. We focus on stable LAP, which are those LAP that remain true once they become true. We propose a scale-free algorithm to detect stable LAP within a k-height BFST. Our algorithm can detect both stable conjunctive LAP and stable relational LAP. In the process of designing our algorithm, we also propose the first distributed algorithm for building a BFST within an area of interest in a graph, and the first distributed algorithm for recording a consistent sub-cut within the area of interest. This paper demonstrates that LAPs are a natural fit for detecting distributed properties in large-scale distributed systems, and stable LAPs can be practically detected at low cost. 相似文献
963.
专家系统在注塑模结构设计中的应用 总被引:2,自引:0,他引:2
介绍了知识库与推理机分离专家系统的原理及程序实现方法,并给出了专家系统的应用实例。 相似文献
964.
Social network has extended its popularity from the Internet to mobile domain. Personal mobile devices can be self-organized and communicate with each other for instant social activities at any time and in any places to achieve pervasive social networking (PSN). In such a network, various content information flows. To which extent should mobile users trust it, whilst user privacy can also be preserved? Existing work has not yet seriously considered trust and reputation management, although trust plays an important role in PSN. In this paper, we propose PerContRep, a practical reputation system for pervasive content services that can assist trustworthy content selection and consumption in a pervasive manner. We develop a hybrid trust and reputation management model to evaluate node recommendation trust and content reputation in the context of frequent change of node pseudonyms. Simulations show the advantages of PerContRep in assisting user decisions and its effectiveness with regard to unfair rating attack, collaborative unfair rating attack, on-off attack and conflict behavior attack. A prototype system achieves positive user feedback on its usability and social acceptance. 相似文献
965.
研究了二氧化碳与己二胺甲氧羰基化反应合成六亚甲基二异氰酸酯,考察了有机碱用量、反应温度、反应时间和压力等操作条件对反应的影响。结果表明最佳工艺条件:n(三乙胺):n(己二胺)=3:1,反应温度-5℃、反应时间60min、压力为0.55MPa。并用红外谱图和折光率对合成产物进行表征。 相似文献
966.
967.
968.
采用种子乳液聚合法,以交联型软性聚合物为核,交联型硬性高聚物为壳,合成了具有优异耐寒性及高温抗回粘性聚合物。讨论了乳化剂种类及应用、核/壳比等对聚合物性能的影响。 相似文献
969.
970.
Natural amorphous polymer poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P3HB4HB) containing 41 mol % of 4HB was blended with poly(3‐hydroxybutyrate) (PHB) with an aim to improve the properties of PHB. The influence of P3HB4HB contents on thermal and mechanical properties of the blends was evaluated with differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, stress–strain measurement and thermo gravimetric analyzer. Miscibility of PHB/P3HB4HB blends was mainly decided by the contents of P3HB4HB. When P3HB4HB exceeded 50 wt %, the two polymer phases separated and showed immiscibility. The addition of P3HB4HB did not alter the crystallinity of PHB, yet it diluted the PHB crystalline phase as revealed by DSC studies. DSC and FTIR results showed that the overall crystallinity of the blends decreased remarkably with increasing of P3HB4HB contents. Decreased glass transition temperature and crystallinity imparted desired flexibility for the blends. The ductility of the blends increased progressively with increasing of P3HB4HB content. Thus, the PHB mechanical properties can be modulated by changing the blend composition. P3HB4HB did not significantly improve the thermal stability of PHB, yet it is possible to melt process PHB without much molecular weights loss via blending it with suitable amounts of P3HB4HB. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献