The mesoscale model MM4 is used to simulate the torrential rain associated with Meiyu front occurring on 5—6 July.1991 in the Changjiang-Huaihe Basin.Based on the outputs of the model, the cause of the mesoscale cycl...The mesoscale model MM4 is used to simulate the torrential rain associated with Meiyu front occurring on 5—6 July.1991 in the Changjiang-Huaihe Basin.Based on the outputs of the model, the cause of the mesoscale cyclogenesis on the lower troposphere is investigated in terms of the potential vorticity principle.The results show that because of the favorable pattern of moist isentropic surface,the absolute vorticity increases when cold air with high moist potential vorticity value rapidly slides down southwards along the moist isentropic surface,and then causes the cyclonic vortex development.展开更多
The state narrative of the Chinese nation is to analyze and illustrate the term“Chinese nation"from the perspective of state,aiming to highlight an innate attributes—the nature of starehoodof the Chinese nation...The state narrative of the Chinese nation is to analyze and illustrate the term“Chinese nation"from the perspective of state,aiming to highlight an innate attributes—the nature of starehoodof the Chinese nation.Chinese nation today,unlike"Chinese nation"in its historical form,is a typical nation in modern sense(as the‘nation"in“nation-state").The one in the past originated from the continuous interaction and exchanges among various ethnic groups in ancient China.Such interaction,communication and exchange promoted integration of the ethnic groups,and thus gave the“Chinese nation"in its early stages.Further,the modern form of the"Chinese nation"is endowed with new connotation through modern social and cultural construction.In a word,there is intrinsic continuity between the two forms,each with different connotations in different historical contexts.Both of them,however,are inseparably connected with the state.As a result,the comprehensive understanding of the Chinese nation can never be achieved without insights into as well as detailed analysis of its nature of statehood from the perspective of state.展开更多
With the development of transportation energy power system,new energy vehicles will become the development direction of future vehicles under the pressure of energy and environmental protection.In recent years,scienti...With the development of transportation energy power system,new energy vehicles will become the development direction of future vehicles under the pressure of energy and environmental protection.In recent years,scientists and researchers have made important contributions in the development of power batteries and lightweight key materials.The special issue of"Research and Application of Materials Science"on key materials in the development of new energy vehicles has deeply understood the research activities in this emerging field through six articles selected after strict review.展开更多
Given a list of items and a sequence of variable-sized bins arriving one by one, it is NP-hard to pack the items into the bin list with a goal to minimize the total size of bins from the earliest one to the last used....Given a list of items and a sequence of variable-sized bins arriving one by one, it is NP-hard to pack the items into the bin list with a goal to minimize the total size of bins from the earliest one to the last used. In this paper a set of approximation algorithms is presented for cases in which the ability to preview at most k（〉=2） arriving bins is given. With the essential assumption that all bin sizes are not less than the largest item size, analytical results show the asymptotic worst case ratios of all k-bounded space and offiine algorithms are 2. Based on experiments by applying algorithms to instances in which item sizes and bin sizes are drawn independently from the continuous uniform distribution respectively in the interval [0,u] and [u,l ], averagecase experimental results show that, with fixed k, algorithms with the Best Fit packing（closing） rule are statistically better than those with the First Fit packing（closing） rule.展开更多
基金Supported by the National Natural Science Foundation of China under the Projects No.49775259 and No.40075009.
文摘The mesoscale model MM4 is used to simulate the torrential rain associated with Meiyu front occurring on 5—6 July.1991 in the Changjiang-Huaihe Basin.Based on the outputs of the model, the cause of the mesoscale cyclogenesis on the lower troposphere is investigated in terms of the potential vorticity principle.The results show that because of the favorable pattern of moist isentropic surface,the absolute vorticity increases when cold air with high moist potential vorticity value rapidly slides down southwards along the moist isentropic surface,and then causes the cyclonic vortex development.
文摘The state narrative of the Chinese nation is to analyze and illustrate the term“Chinese nation"from the perspective of state,aiming to highlight an innate attributes—the nature of starehoodof the Chinese nation.Chinese nation today,unlike"Chinese nation"in its historical form,is a typical nation in modern sense(as the‘nation"in“nation-state").The one in the past originated from the continuous interaction and exchanges among various ethnic groups in ancient China.Such interaction,communication and exchange promoted integration of the ethnic groups,and thus gave the“Chinese nation"in its early stages.Further,the modern form of the"Chinese nation"is endowed with new connotation through modern social and cultural construction.In a word,there is intrinsic continuity between the two forms,each with different connotations in different historical contexts.Both of them,however,are inseparably connected with the state.As a result,the comprehensive understanding of the Chinese nation can never be achieved without insights into as well as detailed analysis of its nature of statehood from the perspective of state.
文摘With the development of transportation energy power system,new energy vehicles will become the development direction of future vehicles under the pressure of energy and environmental protection.In recent years,scientists and researchers have made important contributions in the development of power batteries and lightweight key materials.The special issue of"Research and Application of Materials Science"on key materials in the development of new energy vehicles has deeply understood the research activities in this emerging field through six articles selected after strict review.
文摘Given a list of items and a sequence of variable-sized bins arriving one by one, it is NP-hard to pack the items into the bin list with a goal to minimize the total size of bins from the earliest one to the last used. In this paper a set of approximation algorithms is presented for cases in which the ability to preview at most k（〉=2） arriving bins is given. With the essential assumption that all bin sizes are not less than the largest item size, analytical results show the asymptotic worst case ratios of all k-bounded space and offiine algorithms are 2. Based on experiments by applying algorithms to instances in which item sizes and bin sizes are drawn independently from the continuous uniform distribution respectively in the interval [0,u] and [u,l ], averagecase experimental results show that, with fixed k, algorithms with the Best Fit packing（closing） rule are statistically better than those with the First Fit packing（closing） rule.
