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基于组群结构的HFC MAC协议信道接入机制的性能分析 被引量:3
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作者 高飞 王杰 《云南民族学院学报(自然科学版)》 2000年第3期131-133,139,共4页
利用周期查询式限定服务排队系统的有关研究成果,对基于组群结构的HFC(混合光纤同轴)网络MAC(媒质访问控制)协议中申请信息接入信道的机制进行了性能分析.结果表明,在一定条件下,系统的平均排队队长和平均等待时间都具有较好的... 利用周期查询式限定服务排队系统的有关研究成果,对基于组群结构的HFC(混合光纤同轴)网络MAC(媒质访问控制)协议中申请信息接入信道的机制进行了性能分析.结果表明,在一定条件下,系统的平均排队队长和平均等待时间都具有较好的性能. 展开更多
关键词 周期查询 MAC协议 HFC 组群结构 信道接入机制
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山东济宁组群结构大城市地下水资源评价和应急供水探讨 被引量:1
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作者 吴晓华 王凡勇 +1 位作者 朱晓琳 王学森 《地下水》 2007年第5期29-32,49,共5页
阐述了济宁组群结构大城市地下水资源量与开发利用现状,指出因开采地下水产生的环境地质问题,根据现有水源地的开采潜力分析,提出河里、双庙、石桥、大南铺—新驿和济宁城区水源地适宜作为应急供水水源,并采用不同方法计算了应急供水总... 阐述了济宁组群结构大城市地下水资源量与开发利用现状,指出因开采地下水产生的环境地质问题,根据现有水源地的开采潜力分析,提出河里、双庙、石桥、大南铺—新驿和济宁城区水源地适宜作为应急供水水源,并采用不同方法计算了应急供水总量。当济宁市城区水源地无法供水时,在无新增供水水源的情况下,其它应急水源地的供水保证程度(按2010年规划需水量计算)为60%,可基本满足城市生活供水需求。 展开更多
关键词 济宁组群结构大城市 地下水资源 应急供水
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组群结构城市轨道交通路网规划
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作者 薛锋 《城市公共交通》 2006年第1期33-36,共4页
组群结构城市有其自身的特点及交通特征,本文分析了组群结构城市轨道交通建设的必要性、交通模式和功能定位,阐述了轨道交通路网规划的主要原则、路网图型的选择和路网合理规模的计算,从而确定了需要控制的线网总规模.
关键词 组群结构 轨道交通 路网规划 合理规模
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2014年夏季长江口邻近海域水母类组群结构 被引量:1
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作者 何浩阳 林华 +3 位作者 李伟巍 张格 崔文会 郑连明 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2020年第S01期128-132,共5页
利用2014年7月在长江口邻近海域进行大面调查浮游动物网采样品的分析数据,探讨了该海域水母类的种类组成、优势种、丰度分布及组群结构.结果表明:研究水域共记录水母类13种,其中水螅水母9种,管水母3种,栉水母1种;优势种为四叶小舌水母(L... 利用2014年7月在长江口邻近海域进行大面调查浮游动物网采样品的分析数据,探讨了该海域水母类的种类组成、优势种、丰度分布及组群结构.结果表明:研究水域共记录水母类13种,其中水螅水母9种,管水母3种,栉水母1种;优势种为四叶小舌水母(Liriope tetraphylla)和五角水母(Muggiaea atlantica),优势种的数量和分布趋势决定了水母类丰度的分布格局.根据各站位水母的种类组成和丰度,用聚类分析法将该海域水母分为2个组群,结合去趋势典范对应分析(DCCA),结果表明影响长江口邻近海域水母动物群落结构的主要环境因子为盐度、温度和pH值. 展开更多
关键词 长江口邻近海域 水母类 优势种 组群结构 去趋势典范对应分析(DCCA)
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积极实施城市化战略 加快建设济宁组群结构特大城市
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作者 蒙建华 《山东经济战略研究》 2001年第3期23-25,共3页
关键词 济宁市 城市化道路 组群结构特大城市 城市规划 基础设施建设 管理体制
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大环境 大绿化 推进建设组群结构大城市步伐——浅谈济宁市高标准建设现代化生态城市
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作者 田恒慧 《园林科技》 2001年第S1期115-117,共3页
本文从十个部分谈了济宁市建设生态园林城市及组群结构大城市建设的基本思路及一些基本做法和相应措施,并对今后发展济宁市这个特大城市进行了分析和探讨。
关键词 大环境 大绿化 园林生态城市 组群结构大城市
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组群结构视角下异质性消费者的识别及成因分析
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作者 任燕燕 李东霖 《中国管理科学》 CSSCI CSCD 北大核心 2023年第3期228-237,共10页
本文依据两期消费决策模型,利用CFPS家庭数据构建具有组群结构的面板结构模型,基于C-lasso方法根据数据自身特征,引入信息准则验证组群结构的存在,并确定组群数量和调整参数,从而实现对异质性消费者的自动识别。与传统方法和机器学习中... 本文依据两期消费决策模型,利用CFPS家庭数据构建具有组群结构的面板结构模型,基于C-lasso方法根据数据自身特征,引入信息准则验证组群结构的存在,并确定组群数量和调整参数,从而实现对异质性消费者的自动识别。与传统方法和机器学习中的聚类方法相比,本文提出的方法的信息准则值较小,说明对异质性消费者的识别具有更高的精确度。实证结果表明,我国消费者可以划分为两个组群,而不同组群消费者的暂时性收入变化和家庭资产对消费的影响存在差异,家庭资产、受教育水平和城乡类别在不同组群消费者之间亦存在显著差异,这也验证了上述识别方法的科学性和客观性。此外,研究发现,家庭资产不同的流动性配置是导致消费者异质性的原因。 展开更多
关键词 面板结构模型 C-lasso方法 组群结构 异质性消费者 家庭资产流动性
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多水平零膨胀计数模型在骨关节疼痛影响因素中的应用研究 被引量:4
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作者 田娇妮 刘桂芬 +1 位作者 张军锋 罗天娥 《中国卫生统计》 CSCD 北大核心 2012年第1期44-46,共3页
目的针对两地区村民骨关节调查资料组群结构且零过多问题,阐明多水平零膨胀计数回归模型。方法介绍多水平Poisson和多水平ZIP模型原理,进一步完成山西省农村地区居民风湿性骨关节疼痛部位数影响因素分析的多水平模型SAS软件实现。结果... 目的针对两地区村民骨关节调查资料组群结构且零过多问题,阐明多水平零膨胀计数回归模型。方法介绍多水平Poisson和多水平ZIP模型原理,进一步完成山西省农村地区居民风湿性骨关节疼痛部位数影响因素分析的多水平模型SAS软件实现。结果多水平ZIP回归部分的随机项表明,两调查地区不同村庄居民关节是否疼痛以及疼痛部位数差别有统计学意义。logistic回归估计参数表明年龄、婚姻状况和高血压是影响关节疼痛与否的主要因素。而Pois-son部分估计结果表明年龄、地区、性别和地区交互作用是居民骨关节疼痛部位数的主要因素。Vuong检验进一步证实多水平ZIP模型比多水平Poisson模型更优。结论多水平ZIP回归模型是解决调查研究中组群结构及零发生次数过多问题模型拟合的最佳选择。 展开更多
关键词 组群结构 零过多 多水平零膨胀计数模型
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Polygynous Mating System and Behavioural Reason of Black Crested Gibbon (Nomascus concolor jingdongensis) at Dazhaizi,Mt.Wuliang, Yunnan,China 被引量:12
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作者 范朋飞 蒋学龙 +1 位作者 刘长铭 罗文寿 《Zoological Research》 CAS CSCD 北大核心 2006年第2期216-220,共5页
The field research on five black crested gibbon groups, recently performed at Dazhaizi, Mr. Wuliang, Central Yunnan, China, showed that all groups in the local population consisted of one adult male, two adult females... The field research on five black crested gibbon groups, recently performed at Dazhaizi, Mr. Wuliang, Central Yunnan, China, showed that all groups in the local population consisted of one adult male, two adult females and 2 - 5 sub-adults, juveniles and itfants. The mean group size was 6.2 in August 2003 and 6.4 in August 2005. Two subadult males disappeared from their natal home range and three newborns were given birth in Group 3 (G3) and G4 during this study. The two adult females in G1, G2 and G3 gave births and/or carried babies but at different times. There was no aggressive or dominating behaviour observed between the two adult females. One floating female was first seen in G3's territory on April 15, 2005. The two resident females interrupted her duet with adult male and chased her. We did not observe adult male chased this floating female and she left G3's territory 10 days later. Sub-adult males often kept distance with the family, and they often sang solo bouts in their natal territory before they dispersed. The sub-adult males and females dispersed from natal territory and two adult resident females rejected the third one, which might were the reasons why the black gibbon groups were polygyny in Dazhaizi. 展开更多
关键词 Nomascus concolor jingdongensis Group size and composition Social structure Polygyny Local population Wuliang Mountain
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淄博市城市空间发展分析 被引量:1
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作者 王彬 《淮阴师范学院学报(自然科学版)》 CAS 2003年第3期250-254,共5页
淄博市系历史上相对独立、互不统属的五个主要行政单元逐渐发展演变而来,最终形成的 组群式"结构布局的大城市.这种布局一方面有利于规划,有利于城市各项功能的全面发展.既保护了环境,维护了城市生态平衡,又避免了交通拥挤、住房... 淄博市系历史上相对独立、互不统属的五个主要行政单元逐渐发展演变而来,最终形成的 组群式"结构布局的大城市.这种布局一方面有利于规划,有利于城市各项功能的全面发展.既保护了环境,维护了城市生态平衡,又避免了交通拥挤、住房困难等城市问题;另一方面,其吸引力和辐射力又不及集中式大城市,且各功能区相对独立,空间模式趋同,不易形成大城市风貌.本文在分析淄博市城市结构利弊的同时,对淄博市的发展提出了自己的建议. 展开更多
关键词 淄博 组群结构布局 发展方向
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Influence of a large dam on the longitudinal patterns of fish assem- blages in Qingyi Stream 被引量:5
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作者 Xiao-Yun SUI Zhi LU +2 位作者 Yun-Zhi YAN Yi-Feng CHEN Yin-Tao JIA 《Zoological Research》 CAS CSCD 北大核心 2014年第5期362-372,共11页
Using seasonally collected data(2009-2010) from 15 sampling sites that represent first- to fifth-order streams within the Qingyi watershed,we examined the spatio-temporal patterns of fish assemblages along two longitu... Using seasonally collected data(2009-2010) from 15 sampling sites that represent first- to fifth-order streams within the Qingyi watershed,we examined the spatio-temporal patterns of fish assemblages along two longitudinal gradients to explore the effects of a large dam on fish assemblages at the watershed scale.No significant variation was observed in either species richness or assemblage structure across seasons.Species richness significantly varied according to stream order and gradient.Dam construction appeared to decrease species richness upstream substantially,while a significant decrease between gradients only occurred within fourth-order streams.Along the gradient without the large dam,fish assemblage structures presented distinct separation between two neighboring stream orders,with the exception of fourth-order versus fifth-order streams.However,the gradient disrupted by a large dam displayed the opposite pattern in the spatial variation of fish assemblages related with stream orders.Significant between-gradient differences in fish assemblage structures were only observed within fourth-order streams.Species distributions were determined by local habitat environmental factors,including elevation,substrate,water depth,current discharge,wetted width,and conductivity.Our results suggested that dam construction might alter the longitudinal pattern in fish species richness and assemblage structure in Qingyi Stream,despite the localized nature of the ecological effect of dams. 展开更多
关键词 Fish assemblage Species richness Spatiotemporal pattern Longitudinal gradient Dam building
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Construction of some hypergroups from combinatorial structures
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作者 AliRezaAshrafi AhmadRezaEslami-Harandi 《Journal of Zhejiang University Science》 CSCD 2003年第1期76-79,共4页
Jajcay's studies( 1993 ; 1994) on the automorphism groups of Cayley maps yielded a new product of groups, which he called, rotary product. Using this product, we define a hyperoperation ⊙ on the group Syme (G) , ... Jajcay's studies( 1993 ; 1994) on the automorphism groups of Cayley maps yielded a new product of groups, which he called, rotary product. Using this product, we define a hyperoperation ⊙ on the group Syme (G) , the stabilizer of the identity e ∈ G in the group Sym (G) . We prove that ( Syme (G) , ⊙) is a hypergroup and characterize the subhypergroups of this hypergroup.Finally, we show that the set of all subhypergroups of Syme ( G ) constitute a lattice under ordinary join and meet and that the minimal elements of order two of this lattice is a subgroup of Aut (G) . 展开更多
关键词 Finite group Rotary closed subgroup HYPERGROUP Sub hypergroup Combinatorial structures
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Effects of a patchy seagrass meadow on the macrobenthic community
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作者 MENG Zhou YAN Runxuan HAN Qingxi 《Marine Science Bulletin》 2022年第1期72-88,共17页
Based on macrobenthos collected from intertidal seagrass bed in Guangrao,Shandong Province in May 2013,the macrobenthic structure and diversity were analyzed.A total of 41 macrobenthic species were identified,among wh... Based on macrobenthos collected from intertidal seagrass bed in Guangrao,Shandong Province in May 2013,the macrobenthic structure and diversity were analyzed.A total of 41 macrobenthic species were identified,among which crustaceans were the most speciose macrobenthic taxa(16 species),followed by polychaetes(15 species)and mollusks(10 species).Seven dominant macrobenthic species were identified,including 3 species of polychaetes,2 species of crustaceans and 2 species of mollusks.The total abundance across the whole sampling area was 661.33 ind/m2.Total abundance and the abundance of Potamocorbula laevis and Heteromastus filiformis showed significant spatial variation,and the macrobenthic abundance distributed in seagrass meadows was higher than that in other areas.The results of cluster,nMDS ordination,SIMPER and IMS analyses all showed no linear correlation along the distance gradient from the seagrass meadow.Therefore,degraded seagrass can still provide detectable but limited ecological services.However,the rehabilitation of seagrass bed is essential and urgent to regain their full ecological function. 展开更多
关键词 Guangrao SHANDONG seagrass bed MACROBENTHOS community composition and structure
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Development of Small and Medium Enterprises (SMEs) Accounting Information System in Cluster of Kampung Laweyan Batik, Surakarta, Indonesia 被引量:1
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作者 Anita Wijayanti Kartika Hendra Ts 《Chinese Business Review》 2013年第10期698-711,共14页
The role of small and medium enterprises (SMEs) in the economy of a country was quite strategic, however the tightness of the competition, has allowed the SMEs into disadvantageous position. The SMEs need a precise ... The role of small and medium enterprises (SMEs) in the economy of a country was quite strategic, however the tightness of the competition, has allowed the SMEs into disadvantageous position. The SMEs need a precise accounting information system, thus the SMEs could improve the accuracy, validation data, productivity, and the competitiveness of enterprises. The problem of this research is how the SMEs accounting information systems in a cluster of Kampung Batik Laweyan Surakarta. To develop accounting information systems in a SMEs cluster of Kampung Batik Laweyan Surakarta, this research used research and development (R&D) method. Data obtained through analysis of the company's business processes. Results of data analysis used to develop accounting information systems in a SMEs cluster of Kampung Batik Laweyan Surakarta. Accounting information system development consists of the structure of SMEs organizations, the general design of accounting information systems of the SMEs, flowchart and documentation of the SMEs accounting information systems, and accounting software of the SMEs 展开更多
关键词 SMES accounting information system BATIK
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Site-Floristic Variability of Foxteil Meadows in Poland
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作者 Anna Kryszak Jan Kryszak Agnieszka Klarzynska Agnieszka Strychalska 《Journal of Life Sciences》 2015年第5期197-206,共10页
On the basis of multifaceted investigations of approximately 600 phytosociological surveys of foxtail meadows taken in years 2002-2012 in river valleys with the assistance of the Braun-Blanquet method, the authors car... On the basis of multifaceted investigations of approximately 600 phytosociological surveys of foxtail meadows taken in years 2002-2012 in river valleys with the assistance of the Braun-Blanquet method, the authors carried out evaluation of the floristic composition with respect to phytosociological structure, floristic variability, degree of synanthropisation and life form structures. In addition, they ascertained the dependence of floristic variability of Alopecuretum pratensis phytocenoses on site conditions determined using: the phytoindication method and the laboratory analyses assessed the soil content of available forms of P and K and of Mg. The greatest areas among the recognised syntaxons are taken up by patches of a typical sub-association developed in fresh sites on soils of lightly acid reaction and moderate nitrogen availability. Floristic variability of Alopecuretum pratensis is characterised by: presence in the phytosociological structure of species characteristic for other syntaxons, floristic abundance and botanical structure, domination of species of the 1 st and 2nd degree of stability, high proportion of synanthropic species, values of the floristic diversity index (H'), natural and fodder score values. Geobotanical variability of foxtail meadows confirms difficulties with unequivocal determination of the systematic position of the Alopecuretum pratensis association. 展开更多
关键词 Foxtail meadows floristic variability habitat conditions.
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Community Structure of Urban Forest and Disposition Characteristics of Trees in Hefei Ring Park 被引量:7
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作者 WUZemin WANGYuan ZHANGShaojie YANGHaiyan XUYinbi 《Chinese Forestry Science and Technology》 2004年第3期53-59,共7页
Themethods of vegetation ecology were used to analyze the community structure of Hefei Ring Park, andspecies composition, distribution patternoftree heightand DBH weredescribed.Through calculation of tree growth index... Themethods of vegetation ecology were used to analyze the community structure of Hefei Ring Park, andspecies composition, distribution patternoftree heightand DBH weredescribed.Through calculation of tree growth index and association correlation of component species, the community structures were analyzed. The results showed that community structures are complex, there are 22 pairs of species with positive association, and tree individual in the following communities grow well and are more stable, the majorarePlatycladus orientalis-Prunuscerasifera f.atropurpurea-Osmanthusfragrans, Robinia pseduacacia- Ligustrum lucidum,Robinia pseudoacacia-Ginkgobiloba-Photinia serrulata,Populuscadadensis-Ligustrum lucidum-Osmanthusfragrans, Sophora japonica-Ligustrum lucidum-Buxussinica, Cyclobalanopsis glauca- Distylium racemosum. 展开更多
关键词 community structure species composition association of species tree arrangement China
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