Steps of manipulation is required to complete the m od eling of the connection elements such as bolt, pin and the like in commerce CAD system. It leads to low efficiency, difficulty to assure the relative position, im...Steps of manipulation is required to complete the m od eling of the connection elements such as bolt, pin and the like in commerce CAD system. It leads to low efficiency, difficulty to assure the relative position, impossibility to express rules and knowledge. Based on the inner character analy sis of interpart, detail modification and assembly relation of mechanical connec ting element, the idea, which extends the feature modeling of part to the interp art feature modeling for assembly purpose, is presented, and virtual part based connecting element modeling is proposed. Virtual part is a complement set of lo cal modification of part to be connected. In assembly modeling, base part is mod ified by Boolean operation between base part and virtual part. The modeling and assembly is finished just in one operation, at the same time the rules and knowl edge of the connection elements are encapsulated through virtual part. According to this mechanism, a knowledge-based connecting elements rapid design module i s developed on commerce software package UG with satisfying results.展开更多
数字化变电站通信网络CNDS(Communication Network of Digital Substation)与传统变电站自动化系统中的通信网络在结构、功能、性能和重要性等方面存在较大差异。在IEC 61850标准对变电站自动化系统功能分层的要求和明确数字化变电站通...数字化变电站通信网络CNDS(Communication Network of Digital Substation)与传统变电站自动化系统中的通信网络在结构、功能、性能和重要性等方面存在较大差异。在IEC 61850标准对变电站自动化系统功能分层的要求和明确数字化变电站通信网络效能目标的基础上,提出了过程层点对点/多点、过程层总线和站内统一网络3种数字化变电站通信网络组网方式;指出前2种组网方式目前较易实现,而站内统一网络将凭借信息高度共享等优势成为数字化变电站通信网络的最终形态。在分析以太网介质访问控制方法的基础上,针对标准以太网存在延时不确定的问题,提出了改进以太网实时性能的若干措施,并从中选择出适用于数字化变电站通信网络的方法。研究了数字化变电站通信网络广播域的划分方法。展开更多
Based on electrical capacitance tomography technique, a novel method for flow pattern display and voidage measurement of two-phase flow was proposed. A 12-electrode ECT measurement system was developed. The weighted b...Based on electrical capacitance tomography technique, a novel method for flow pattern display and voidage measurement of two-phase flow was proposed. A 12-electrode ECT measurement system was developed. The weighted back projection algorithm was selected as the image reconstruction algorithm to satisfy the requirement of flow pattern display. Combining the principle of Tikhnov regularization theory with the ART(Algebraic Reconstruction Technique) algorithm, a new quantitative image reconstruction algorithm was developed to implement voidage measurement of two-phase flow. Experimental results of gas-liqiud two-phase flow and gas-solid fluidized bed showed that the developed measurement system was successful. The speed of image reconstruction of flow pattern display was greater than 20 frames per second. The maximum error of voidage measurement is less than 5% and the time of voidage measurement is less than 2 seconds.展开更多
文摘Steps of manipulation is required to complete the m od eling of the connection elements such as bolt, pin and the like in commerce CAD system. It leads to low efficiency, difficulty to assure the relative position, impossibility to express rules and knowledge. Based on the inner character analy sis of interpart, detail modification and assembly relation of mechanical connec ting element, the idea, which extends the feature modeling of part to the interp art feature modeling for assembly purpose, is presented, and virtual part based connecting element modeling is proposed. Virtual part is a complement set of lo cal modification of part to be connected. In assembly modeling, base part is mod ified by Boolean operation between base part and virtual part. The modeling and assembly is finished just in one operation, at the same time the rules and knowl edge of the connection elements are encapsulated through virtual part. According to this mechanism, a knowledge-based connecting elements rapid design module i s developed on commerce software package UG with satisfying results.
文摘数字化变电站通信网络CNDS(Communication Network of Digital Substation)与传统变电站自动化系统中的通信网络在结构、功能、性能和重要性等方面存在较大差异。在IEC 61850标准对变电站自动化系统功能分层的要求和明确数字化变电站通信网络效能目标的基础上,提出了过程层点对点/多点、过程层总线和站内统一网络3种数字化变电站通信网络组网方式;指出前2种组网方式目前较易实现,而站内统一网络将凭借信息高度共享等优势成为数字化变电站通信网络的最终形态。在分析以太网介质访问控制方法的基础上,针对标准以太网存在延时不确定的问题,提出了改进以太网实时性能的若干措施,并从中选择出适用于数字化变电站通信网络的方法。研究了数字化变电站通信网络广播域的划分方法。
基金国家自然科学基金青年基金 (No .2 970 6 0 0 8)国家自然科学基金重大项目 (No .5 9995 46 0 -5 )资助项目~~
文摘Based on electrical capacitance tomography technique, a novel method for flow pattern display and voidage measurement of two-phase flow was proposed. A 12-electrode ECT measurement system was developed. The weighted back projection algorithm was selected as the image reconstruction algorithm to satisfy the requirement of flow pattern display. Combining the principle of Tikhnov regularization theory with the ART(Algebraic Reconstruction Technique) algorithm, a new quantitative image reconstruction algorithm was developed to implement voidage measurement of two-phase flow. Experimental results of gas-liqiud two-phase flow and gas-solid fluidized bed showed that the developed measurement system was successful. The speed of image reconstruction of flow pattern display was greater than 20 frames per second. The maximum error of voidage measurement is less than 5% and the time of voidage measurement is less than 2 seconds.
