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Polya计数定理及其若干性质
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作者 邓记养 《韶关学院学报》 1987年第2期1-7,共7页
G·Polya是美籍匈牙利数学家、教育家。他在数学的广泛领域里都有许多发现,又热心于教育,1980年被邀请担任第四次国际数学教育会议的名誉主席。他一生中发表过二百多篇论文和许多专著,其作品清晰优美,方法灵巧独特。被人们誉为“Po... G·Polya是美籍匈牙利数学家、教育家。他在数学的广泛领域里都有许多发现,又热心于教育,1980年被邀请担任第四次国际数学教育会议的名誉主席。他一生中发表过二百多篇论文和许多专著,其作品清晰优美,方法灵巧独特。被人们誉为“Polya的风格”、“Polya的方法”……。Polya早在1937年就对树的计数和化合物的同分异构体的枚举问题进行研究。 展开更多
关键词 计数级数 计数定理 构形群 置换 循环 性质 国际数学教育 同分异构体 格式 二进制数
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Late Cenozoic Tectonic Deformation in the Dongsha Islands and Adjacent Sea Area 被引量:6
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作者 吴时国 刘展 +3 位作者 王万银 郭军华 T.Lüdmann H.K.Wong 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2003年第4期377-388,共12页
Dongsha Island and the adjacent sea area locate at the northern continental margin of the South China Sea (SCS), and is connected to the east by the Manila Trench. Analyses of seismic stratigraphy and gravity, magneti... Dongsha Island and the adjacent sea area locate at the northern continental margin of the South China Sea (SCS), and is connected to the east by the Manila Trench. Analyses of seismic stratigraphy and gravity, magnetic and drilling wells data led to the discovery of three post fault sequences (V, VI, VII). Extensive tectonic uplift, magma activity and erosion occurred in Dongsha Island and the adjacent area, where most of the faults in the northeastern SCS were still active during Pliocene and Quaternary. Two groups of faults trending NEE and NW were developed during Late Cenozoic. We conclude that three important tectonic movements, especially Dongsha movement (4.4-5.2 Ma) and Liuhua movement (1.4-1.89 Ma), controlled the structural framework in the Dongsha rise; whose deformation in the east is stronger than that in the west and whose stress field variation suggests that the tectonic uplift in the study area contributed to magmato tectonic events correlated to the main collision phases between the East China and Taiwan 5-3 and 3-0 Ma ago. 展开更多
关键词 Late Cenozoic tectonic movement seismic stratigraphy plate collision South China Sea
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Morphological and karyotypic variation in three wild populations of Meretrix meretrix 被引量:1
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作者 邓岳文 杜晓东 +1 位作者 黄荣莲 王庆恒 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2008年第1期76-80,共5页
Three wild populations of Meretrix meretrix sampled from Dongxing, Beihai, and Shankou along the coast of Guangxi, China, were investigated with morphometry and karyometry. Six morphological indices (shell length, she... Three wild populations of Meretrix meretrix sampled from Dongxing, Beihai, and Shankou along the coast of Guangxi, China, were investigated with morphometry and karyometry. Six morphological indices (shell length, shell height, shell width, hinge length, total wet weight and shell weight) were measured. Differences in all morphological indices except hinge length were significant among the three populations (P < 0.05). The mean values of these indices (except for the hinge length) in the Dongxing population were larger than those in the Beihai and Shankou populations, although the latter had the largest hinge length. The karyotype of the Beihai, Shankou and Dongxing samples had ten metacentric, six submetacentric, and three subtelocentric chromosome pairs. No significant difference was shown in the centromeric index values of the chromosomes in the populations (P>0.05). However, the order of metacentric, submetacentric and subtelocentric chromosome pairs was variable among the three populations. The results indicate a high level of inter-population variation in morphology and karyotype. 展开更多
关键词 Meretrix meretrix POPULATION MORPHOLOGY KARYOTYPE
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Reconfiguration of Spacecraft Cluster Based on Distributed Local Information
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作者 YU Binggu WANG Shuquan 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2021年第4期704-712,共9页
The reconstruction of spacecraft cluster based on local information and distributed strategy is investigated.Each spacecraft is an intelligent individual that can detect information within a limited range and can dete... The reconstruction of spacecraft cluster based on local information and distributed strategy is investigated.Each spacecraft is an intelligent individual that can detect information within a limited range and can determine its behavior based on surrounding information.The objective of the cluster is to achieve the formation reconstruction with minimum fuel consumption.Based on the principle of dual pulse rendezvous maneuver,three target selection strategies are designed for collision avoidance.Strategy-1 determines the target point’s attribution according to the target’s distance when the target point conflicts and uses a unit pulse to avoid a collision.Strategy-2 changes the collision avoidance behavior.When two spacecraft meet more than once,the strategy switches the target points of the two spacecraft.In Strategy-3,the spacecraft closer to the target has higher priority in target allocation.Strategy-3 also switches the target points when two spacecraft encounter more than once.The three strategies for a given position,different completion times,and random position are compared.Numerical simulations show that all three strategies can accomplish the spacecraft cluster's reconfiguration under the specified requirements.Strategy-3 is better than Strategy-1 in all simulation cases in the sense of less fuel consumption with different completion times and given location,and it is more effective than Strategy-2 in most of the completion time.With a random initial position and given time,Strategy-3 is better than Strategy-1 in about 70%of the cases and more stable. 展开更多
关键词 spacecraft cluster formation reconstruction relative Lambert problem two-impulse rendezvous distributed maneuver
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Morphometric Data of Testudo hermanni in the Vlora Area
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作者 Hajdar Kieaj Enerit Sacdanaku Berlinda Shkurtaj 《Journal of Life Sciences》 2016年第6期307-311,共5页
The purpose of this paper is the morphometric study as well as the assessment of population structure of the Testudo hermani tortoise in the Vlora area. Individuals are collected in the study area. A morphometric stud... The purpose of this paper is the morphometric study as well as the assessment of population structure of the Testudo hermani tortoise in the Vlora area. Individuals are collected in the study area. A morphometric study is made for the caught individuals. Suitable habitats have been identified for their growth and development. It is estimated the number of healthy or unhealthy individuals, dead individuals and also the identification of the local population's threatening factors. Individuals with anomalies are studied and then compared with normal individuals, especially in terms of the number and shape of the dermal plates. 展开更多
关键词 Testudo hermanni morphometric study population structure habitat.
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GROUP ACTIONS ON VON NEUMANN REGULAR RINGS
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作者 ZHANG YINHUO(Institute of Mathematics,Fudan University, Shanghai 200433, China) 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 1994年第2期235-240,共6页
Let A be a ring with indentity, G a finite group of automorphisms of A. The main result of this paper is that A/AG is Galois if and only if it is Frobenius and the module AGA (or AAG)is faithful. Moreover if |G| is in... Let A be a ring with indentity, G a finite group of automorphisms of A. The main result of this paper is that A/AG is Galois if and only if it is Frobenius and the module AGA (or AAG)is faithful. Moreover if |G| is invertible the author improves [2, Theorem 8] and [3, Theorem 8]. 展开更多
关键词 Von Neumann regular ring EXTENSION GROUP Automorphism.
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