CMOS轨到轨电压跟随器的设计及优化

电压跟随器的电压放大倍数总是小于且趋近于1,它具有低输出阻抗、高输入阻抗的特点.也就是说在理想的情况下,从前级电路看去电压跟随器相当于断路,从后级电路看去电压跟随器又相当于一个恒压源.在具体电路中,电压跟随器一般做缓冲级和隔离级,并起着前后级阻抗匹配的作用.文中提出一种AB类高性能CMOS轨到轨电压跟随器,电路是以AB类对称式电压跟随器为基础设计的.     

法律拟制的人格权研究

法律的发展是一个社会文明进步、依法治国的过程,也是一个人们权利意识觉醒并不断寻求权益保护的过程。近代以来,特别是第二次世界大战以后对作为主体权益重要内容的人格权益的反思与进一步的发展使人格权益愈加被重视。加之当今世界经济的发展、社会日益复杂,人格权益受到威胁的范围和深度随之增加,对于人格权益的诉求也延伸到更高层次。人格权益的保护推动着人格权权益研究的不断深入,也使得人格权相关立法不断完善。由于无民事行为能力人和限制民事行为能力人的特殊性,使得人格权的法律保护又有显著不同,探索此种情况下的人格权保护将对正处于社会转型期的中国人格权研究产生巨大影响。     

高职高专辅导员工作方法的探索——从“刀刃”之意谈“查与察”、“刚与柔”的关系

辅导员工作关系着高校稳定和发展。每个从事学生工作的辅导员,都因个人的性格、知识架构、思维方式等不同而有所不同。一个学生就是一种性格的人,辅导员面对多少学生就必须要有多少种性格的适应能力,才能更加科学、合理地以人为本去做好本职工作。文中从"好钢用在刀刃上"的说法引申指出基于辅导员工作方法的探索,主要是强调辅导员工作中"查与察"和"刚与柔"的关系。     

带有门限的IBP+MMBP/Geo/1/K休假排队系统

建立了基于门限策略的双队列单服务台有限缓存包级休假排队模型IBP+MMBP/Geo/1/K。针对到达分布不同的两种业务各自的特点来定义休假策略,将H2H(Human to human)业务的休假期等效为M2M(Machine to machine)业务的服务期。为了寻求统一的标准来评价休假策略,定义了一个评价业务QoS的效能函数E。同时,研究了不同条件下的M2M业务对休假策略的影响。最后,通过仿真给出各种情况下系统各项性能指标以及效能函数的变化趋势,该研究结果可以用来指导无线资源分配和业务配置等问题。     

考虑粘性泥沙运动的黄河口二维水沙输移数学模型

为研究黄河口的水沙输移规律,采用基于无结构三角网格下的有限体积法建立了平面二维水沙数学模型.模型中分别采用不同方法处理粘性和非粘性沙的输移源项,并引入经验证的粘性沙输移源项改进公式.采用已有的概化水槽冲淤试验资料对模型进行了验证,然后应用于1982年6月至1983年5月期间黄河口水沙输移的数值模拟,计算得到的潮位过程及冲淤量与实测资料符合较好,结果表明模型能够较好地模拟考虑粘性沙运动的黄河口非均匀沙不平衡输移.最后比较了不同泥沙输移源项处理方式对模拟结果的影响,计算表明在黄河口水沙输移数值模拟中需要采用非均匀沙模型并同时考虑粘性和非粘性泥沙的输移.     

基于P2P的师生互助系统的研究

P2P技术成为目前网络通信的主流技术之一,由于具有通信过程不易受单点故障影响以及易于扩展的特性,使其得到广泛应用。首先介绍P2P相关技术,详细设计基于P2P的师生互助系统的功能模块,研究系统实现的关键技术。系统的实施可以方便师生实时共享资源,改变传统的教学方式,提高教学效果。实践表明：系统运行性能稳定,对师生互助交流起到一定的促进作用。     

Flow structure through pool‐riffle sequences and a conceptual model for their sustainability in gravel‐bed rivers

Detailed field measurements and simulations of three‐dimensional flow structure were used to develop a conceptual model to explain the sustainability of self‐formed pool‐riffle sequences in gravel‐bed rivers. The analysis was conducted at the Red River Wildlife Management Area in Idaho, USA, and enabled characterization of the flow structure through two consecutive pool‐riffle sequences, including: identification of jet concentration and dissipation zones, and the development of local turbulence features (i.e. vertical and horizontal eddies) under different flow conditions. Three‐dimensional hydraulic simulations were used to evaluate how the flow structure varies across a range of flow conditions and with different degrees of sediment aggradation within the upstream pool. The analysis demonstrated a significant influence of the residual pool depth on the flow structure, with reduced residual depth causing a shift in the orientation of the jet and a reduction in the influence of vertical eddies and the size and intensity of horizontal eddies. The proposed conceptual model seeks to explain the sustainability of pools in terms of the flow structure in pool‐riffle morphology and how this flow structure will change as a result of altered external forcing, such as upstream sediment delivery or changes in bank stability. Copyright © 2010 John Wiley & Sons, Ltd.     

AMPHIBIAN OCCUPANCY IN FLOOD‐CREATED AND EXISTING WETLANDS OF THE LOWER MISSOURI RIVER ALLUVIAL VALLEY

During the previous century, the wetland area in the lower Missouri River alluvial valley was reduced by 39% because of river channelization and bank stabilization projects. The Great Flood of 1993 reversed the trend of wetland loss by creating 466 new wetlands in the alluvial valley between Kansas City and St. Louis, Missouri. We estimated amphibian occupancy, detection probability and number of species exhibiting evidence of reproduction in eight flood‐created and 16 pre‐flood existing wetlands from 1996 through 1998. We also evaluated whether hydroperiod (the number of days any water was present in a wetland from 20 February through 31 August) and distance to river predicted those values. Detection probabilities for adult amphibian species were relatively constant across years and ranged from 0.013 [Great Plains toad (Anaxyrus cognatus)] to 0.280 [Woodhouse's toad (Anaxyrus woodhousii woodhousii)]. Occupancy of adult amphibians differed across years and was not correlated with habitat features. Estimated occupancy probabilities for amphibian species ranged from 0.126 [Plains spadefoot (Spea bombifrons)] to 0.896 [boreal chorus frog (Pseudacris maculata)]. Almost double the number of amphibian species showed evidence of reproduction in existing wetlands (wetlands created before the Great Flood of 1993) when compared with that in flood‐created wetlands. Similarly, temporary wetlands had nearly double the number of amphibian species showing evidence of reproduction when compared with permanent wetlands. Finally, the highest number of species showed evidence of reproduction in wetlands with spring–summer hydroperiods between 135 and 140 days. All these relationships suggest that the invasion and persistence of predators in wetlands negatively influence amphibian reproduction. If the Missouri River is allowed to reconnect with the alluvial valley, more predators may be introduced into wetlands, leading to reduced amphibian occupancy and reproduction. However, this connection will not likely occur over the entire alluvial valley and, therefore, should not adversely impact amphibians that find refuge in higher‐elevation, non‐connected regions of the alluvial valley. Copyright © 2011 John Wiley & Sons, Ltd.     

WATER QUALITY ASSESSMENT AND APPORTIONMENT OF POLLUTION SOURCES OF TIGRIS RIVER (TURKEY) USING MULTIVARIATE STATISTICAL TECHNIQUES—A CASE STUDY

The Tigris is one of the most important transboundary rivers in western Asia and originates in the Toros mountains of the Eastern Anatolia region of Turkey. Multivariate statistical techniques, such as cluster analysis (CA), principal component analysis (PCA) and factor analysis (FA), were applied for the evaluation of temporal/spatial variations and the interpretation of a water quality data set for the Tigris River, which was obtained during 1 year of monitoring. This study presents the usefulness of multivariate statistical techniques for the evaluation and interpretation of complex water quality data sets and apportionment of pollution sources/factors to obtain better information about water quality and the design of a monitoring network for the effective management of water resources. Hierarchical CA grouped 12 months into two periods (the first and second periods) and classified seven monitoring sites into three groups, that is, less polluted sites, medium polluted sites and highly polluted sites, based on similarities in the water quality characteristics. PCA/FA identified five factors in the data structure, which explained 77.5% of the total variance of the data set. This allowed us to group the selected parameters according to common features and to evaluate the influence of each group on the overall variation in water quality. Varifactors obtained from the factor analysis indicated that the parameters responsible for water quality variation were mainly related to soluble salts (natural), organic pollution and nutrients (anthropogenic). Copyright © 2011 John Wiley & Sons, Ltd.     

桃花江航运枢纽整体水力学试验研究

桃花江旅游景观船闸在布置上因受到枢纽地形与河道防洪的限制,难以满足规范要求.采用几何比尺为1∶25的整体水工模型进行了试验研究,2座枢纽的控制运行条件均为最高通航水位组合,主河道中流速较大,特别是上下游口门处引航道的横向流速较大,不能满足规范要求.修改方案主要通过减小2座船闸上下游引航道与桃花江主河道夹角,并对口门附近地形进行了相应的疏浚.试验结果表明,修改方案有效降低了2座船闸上游口门处横向流速等不利因素.