级联型混合直流系统受端的模块化多电平换流器高压直流系统(modular multilevel converter high voltage direct current,MMC-HVDC)和电网换相换流器高压直流系统(line commutated converter high voltage direct current,LCC-HVDC)会...级联型混合直流系统受端的模块化多电平换流器高压直流系统(modular multilevel converter high voltage direct current,MMC-HVDC)和电网换相换流器高压直流系统(line commutated converter high voltage direct current,LCC-HVDC)会因馈入点电气距离较近而存在强相互作用关系。为明确级联型混合直流馈入系统中MMC-HVDC对LCC-HVDC系统强度的影响,提出考虑幅值和相位的MMC等效电流源的简化等效方法,基于所提MMC等效原理将级联型混合直流馈入系统等效成单馈入LCC-HVDC系统,分析等效单馈入系统的参数计算方法,并提出等效单馈入短路比评估指标。最后通过该指标分析归纳了不同控制方式、不同电气距离下等效单馈入系统的系统强度变化情况,即为MMC-HVDC对LCC-HVDC系统强度的影响规律。机理分析和基于PSCDAD/EMTDC、MATLAB的仿真结果表明,所提等效方法具有有效性且所提指标能很好地反应MMC-HVDC对LCC-HVDC系统强度的影响。展开更多
As a ceramic material,AlN has very good thermophysical and mechanical properties.In addition,AlN is an effective refining agent for Mg alloys because it has a lattice constant similar to that of Mg.Therefore,AlN is an...As a ceramic material,AlN has very good thermophysical and mechanical properties.In addition,AlN is an effective refining agent for Mg alloys because it has a lattice constant similar to that of Mg.Therefore,AlN is an ideal reinforcement for magnesium matrix composites(MMCs),and is attracting increasing attention.This review addresses the development of preparation technologies for AlN-reinforced Mg matrix composites.The mainstream preparation techniques include stir casting,melt infiltration,powder metallurgy,and in-situ methods.In addition,the advantages and disadvantages of these techniques are analyzed in depth,and it is pointed out that the next direction for the preparation of high-performance AlN-reinforced MMCs is less aluminization and multiple technologies integration.展开更多
现代建造方法(Modern Methods of Construction,MMC)是一种建筑系统,它可以根据当今建筑行业出现的新需求缩短建造时间和降低成本,同时建造出质量较高的建筑。MMC主要包括可供制造及装配的设计(Design for Manufacturing and Assembly,D...现代建造方法(Modern Methods of Construction,MMC)是一种建筑系统,它可以根据当今建筑行业出现的新需求缩短建造时间和降低成本,同时建造出质量较高的建筑。MMC主要包括可供制造及装配的设计(Design for Manufacturing and Assembly,DfMA)、组装合成建筑法(Modular Integrated Construction,MiC)及机电装备合成法(Multi-trade Integrated Mechanical,Electrical and Plumbing,MiMEP)等众多概念。以将军澳海水化淡厂项目为例,从DfMA、MiC及MiMEP等方面介绍项目MMC与BIM技术相结合的应用情况。MMC的使用不仅可提高建设速度、优化工期,对节约人工成本、控制工程质量以及营造低碳建造环境等方面也能起到关键作用。MMC的使用最大限度地降低现场劳动力的需求,带动建筑业数字化发展,推动建筑业产业化创新,最终将使建筑业不断迭代升级,实现可持续发展的目标。展开更多
文摘级联型混合直流系统受端的模块化多电平换流器高压直流系统(modular multilevel converter high voltage direct current,MMC-HVDC)和电网换相换流器高压直流系统(line commutated converter high voltage direct current,LCC-HVDC)会因馈入点电气距离较近而存在强相互作用关系。为明确级联型混合直流馈入系统中MMC-HVDC对LCC-HVDC系统强度的影响,提出考虑幅值和相位的MMC等效电流源的简化等效方法,基于所提MMC等效原理将级联型混合直流馈入系统等效成单馈入LCC-HVDC系统,分析等效单馈入系统的参数计算方法,并提出等效单馈入短路比评估指标。最后通过该指标分析归纳了不同控制方式、不同电气距离下等效单馈入系统的系统强度变化情况,即为MMC-HVDC对LCC-HVDC系统强度的影响规律。机理分析和基于PSCDAD/EMTDC、MATLAB的仿真结果表明,所提等效方法具有有效性且所提指标能很好地反应MMC-HVDC对LCC-HVDC系统强度的影响。
基金supported by the National Natural Science Foundation of China(Nos.52175321,and 51771080).
文摘As a ceramic material,AlN has very good thermophysical and mechanical properties.In addition,AlN is an effective refining agent for Mg alloys because it has a lattice constant similar to that of Mg.Therefore,AlN is an ideal reinforcement for magnesium matrix composites(MMCs),and is attracting increasing attention.This review addresses the development of preparation technologies for AlN-reinforced Mg matrix composites.The mainstream preparation techniques include stir casting,melt infiltration,powder metallurgy,and in-situ methods.In addition,the advantages and disadvantages of these techniques are analyzed in depth,and it is pointed out that the next direction for the preparation of high-performance AlN-reinforced MMCs is less aluminization and multiple technologies integration.
文摘现代建造方法(Modern Methods of Construction,MMC)是一种建筑系统,它可以根据当今建筑行业出现的新需求缩短建造时间和降低成本,同时建造出质量较高的建筑。MMC主要包括可供制造及装配的设计(Design for Manufacturing and Assembly,DfMA)、组装合成建筑法(Modular Integrated Construction,MiC)及机电装备合成法(Multi-trade Integrated Mechanical,Electrical and Plumbing,MiMEP)等众多概念。以将军澳海水化淡厂项目为例,从DfMA、MiC及MiMEP等方面介绍项目MMC与BIM技术相结合的应用情况。MMC的使用不仅可提高建设速度、优化工期,对节约人工成本、控制工程质量以及营造低碳建造环境等方面也能起到关键作用。MMC的使用最大限度地降低现场劳动力的需求,带动建筑业数字化发展,推动建筑业产业化创新,最终将使建筑业不断迭代升级,实现可持续发展的目标。