Web服务作为一种新型的Web应用模式,近年来得到了迅速的发展.如何动态地把现存的各种Web服务整合起来以形成新的、满足不同用户需求的、增值的复杂服务已成为新的应用需求和研究热点.针对现有服务聚合中服务选择技术的不足,提出了一种...Web服务作为一种新型的Web应用模式,近年来得到了迅速的发展.如何动态地把现存的各种Web服务整合起来以形成新的、满足不同用户需求的、增值的复杂服务已成为新的应用需求和研究热点.针对现有服务聚合中服务选择技术的不足,提出了一种解决服务聚合中服务动态选择QoS全局最优化问题的实现算法GODSS(global optimal of dynamic Web services selection).算法的主要思想是把服务动态选择全局最优化问题转化为一个带QoS约束的多目标服务组合优化问题,利用多目标遗传算法的智能优化原理,通过同时优化多个目标函数,最终产生一组满足约束条件的Pareto优化服务聚合流程集.理论分析和实验结果说明了算法的可行性和有效性.展开更多
Dynamic properties of rocks are important in a variety of rock mechanics and rock engineering problems. Due to the transient nature of the loading, dynamic tests of rock materials are very different from and much more...Dynamic properties of rocks are important in a variety of rock mechanics and rock engineering problems. Due to the transient nature of the loading, dynamic tests of rock materials are very different from and much more challenging than their static counterparts. Dynamic tests are usually conducted using the split Hopkinson bar or Kolsl^j bar systems, which include both split Hopkinson pressure bar （SHPB） and split Hopkinson tension bar （SHTB） systems. Significant progress has been made on the quantification of various rock dynamic properties, owing to the advances in the experimental techniques of SHPB system. This review aims to fully describe and critically assess the detailed procedures and principles of tech- niques for dynamic rock tests using split Hopkinson bars. The history and principles of SHPB are outlined, followed by the key loading techniques that are useful for dynamic rock tests with SHPB （i.e. pulse shaping, momentum-trap and multi-axial loading techniques）. Various measurement techniques for rock tests in SHPB （i.e. X-ray micro computed tomography （CT）, laser gap gauge （LGG）, digital image corre- lation （DIC）, Moir~ method, caustics method, photoelastic coating method, dynamic infrared thermog- raphy） are then discussed. As the main objective of the review, various dynamic measurement techniques for rocks using SHPB are described, including dynamic rock strength measurements （i.e. dynamic compression, tension, bending and shear tests）, dynamic fracture measurements （i.e. dynamic imitation and propagation fracture toughness, dynamic fracture energy and fracture velocity）, and dy- namic techniques for studying the influences of temperature and pore water.展开更多
This paper provides a detailed analysis of the factors influencing the evolution of rural settlements, including natural environmental constraints, infrastructure, regional cultural inheritance and integration, urbani...This paper provides a detailed analysis of the factors influencing the evolution of rural settlements, including natural environmental constraints, infrastructure, regional cultural inheritance and integration, urbanization and rural industrial transformation, land use refor- mation and innovation, rural household behavior conversion, macro-control policy factors, and so on. Based on differences between the ways and degree of effect on rural settlement evolution, these factors are classified into basic factors, new-type factors and mutation factors The drive of basic factors mainly focuses on the traditional inheritance of rural settlements, the new-type factors mainly affect rural settlement transition, and the mutation factors may bring about sudden changes. All these factors constitute a ＂three-wheel＂ driving mechanism for the evolution of rural settlements, and shape three typical driver paths： slow smooth path under the basic factors, new path to rapid development under the new-type factors, and the sudden change path under the mutation factors. The paper also investigates the overall situation of rural settlement evolution in the aspects of settlement system, settlement scale, settlement morphology, settlement function, settlement culture, settlement environment, etc. The general process of rural settlement evolution is divided into four stages： initial, transi- tional, developmental, and mature stages.展开更多
基金Supported by the National HighTech Research and Development Plan of China under Grant Nos.2002AA1340102002AA1340202003AA135110(国家高技术研究发展计划(863))
文摘Web服务作为一种新型的Web应用模式,近年来得到了迅速的发展.如何动态地把现存的各种Web服务整合起来以形成新的、满足不同用户需求的、增值的复杂服务已成为新的应用需求和研究热点.针对现有服务聚合中服务选择技术的不足,提出了一种解决服务聚合中服务动态选择QoS全局最优化问题的实现算法GODSS(global optimal of dynamic Web services selection).算法的主要思想是把服务动态选择全局最优化问题转化为一个带QoS约束的多目标服务组合优化问题,利用多目标遗传算法的智能优化原理,通过同时优化多个目标函数,最终产生一组满足约束条件的Pareto优化服务聚合流程集.理论分析和实验结果说明了算法的可行性和有效性.
文摘Dynamic properties of rocks are important in a variety of rock mechanics and rock engineering problems. Due to the transient nature of the loading, dynamic tests of rock materials are very different from and much more challenging than their static counterparts. Dynamic tests are usually conducted using the split Hopkinson bar or Kolsl^j bar systems, which include both split Hopkinson pressure bar （SHPB） and split Hopkinson tension bar （SHTB） systems. Significant progress has been made on the quantification of various rock dynamic properties, owing to the advances in the experimental techniques of SHPB system. This review aims to fully describe and critically assess the detailed procedures and principles of tech- niques for dynamic rock tests using split Hopkinson bars. The history and principles of SHPB are outlined, followed by the key loading techniques that are useful for dynamic rock tests with SHPB （i.e. pulse shaping, momentum-trap and multi-axial loading techniques）. Various measurement techniques for rock tests in SHPB （i.e. X-ray micro computed tomography （CT）, laser gap gauge （LGG）, digital image corre- lation （DIC）, Moir~ method, caustics method, photoelastic coating method, dynamic infrared thermog- raphy） are then discussed. As the main objective of the review, various dynamic measurement techniques for rocks using SHPB are described, including dynamic rock strength measurements （i.e. dynamic compression, tension, bending and shear tests）, dynamic fracture measurements （i.e. dynamic imitation and propagation fracture toughness, dynamic fracture energy and fracture velocity）, and dy- namic techniques for studying the influences of temperature and pore water.
基金National Social Science Foundation of China, No.07BJL033 Youth Foundation of Hunan Normal University, No.Z080625 Key Subject of Hunan Normal University about Human Geography
文摘This paper provides a detailed analysis of the factors influencing the evolution of rural settlements, including natural environmental constraints, infrastructure, regional cultural inheritance and integration, urbanization and rural industrial transformation, land use refor- mation and innovation, rural household behavior conversion, macro-control policy factors, and so on. Based on differences between the ways and degree of effect on rural settlement evolution, these factors are classified into basic factors, new-type factors and mutation factors The drive of basic factors mainly focuses on the traditional inheritance of rural settlements, the new-type factors mainly affect rural settlement transition, and the mutation factors may bring about sudden changes. All these factors constitute a ＂three-wheel＂ driving mechanism for the evolution of rural settlements, and shape three typical driver paths： slow smooth path under the basic factors, new path to rapid development under the new-type factors, and the sudden change path under the mutation factors. The paper also investigates the overall situation of rural settlement evolution in the aspects of settlement system, settlement scale, settlement morphology, settlement function, settlement culture, settlement environment, etc. The general process of rural settlement evolution is divided into four stages： initial, transi- tional, developmental, and mature stages.
