基于EPOCHS平台的IEC 61850采样值传输仿真

采样值传输是IEC 61850变电站自动化系统过程层与间隔层之间通信的主要部分。在电力和通信系统同步仿真（EPOCHS）平台上提出IEC 61850变电站通信仿真框架，针对具体变电站构建IEC 61850通信模型。在NS2中添加虚拟局域网（VLAN）IEEE 802.1Q协议代码，实现VLAN多播报文的仿真。对交换式以太网和共享式以太网、接收不同数目合并单元采样值报文的保护设备进行了比较。结果表明:100 Mbit/s交换式以太网完全满足标准要求，而100 Mbit/s共享式以太网采样值报文时延和时延抖动较大，导致工频保护测量值波形畸变;接收多个采样值报文的保护设备存在链路瓶颈问题，对此提出了多通信插件的解决方案。     

变电站GOOSE报文在IED中的实时处理

报文的通信延迟包括传输延迟和处理延迟2部分。IEC 61850标准将面向通用对象的变电站事件（GOOSE）报文直接映射到数据链路层，能有效减少传输延迟。文中对GOOSE报文在变电站智能电子设备（IED）中的处理延迟进行了研究。分析了前后台方式的嵌入式系统在变电站IED中处理实时报文方面的不足，提出在IED中采用具有强实时内核的操作系统，并针对IED中实时报文和非实时报文混合处理环境需求，在RTAI实时操作系统上设计了保障GOOSE报文处理实时性的方案。实验验证了该方案的有效性和实用性。该研究结果对于使用IEC 61850的变电站IED过程总线通信设计具有参考意义。     

采用IEC 61850构造变电站广域保护代理的信息模型

基于代理（Agent）技术的广域后备保护有助于提高电网安全，因此得到人们的关注和研究。文中提出采用IEC 61850构造变电站广域后备保护代理的信息模型。阐述广域后备保护系统分布式对等协商的一般性体系结构，研究保护智能电子设备（IED）中包括广域后备保护代理在内的逻辑节点组成。将保护代理设计成扩展型逻辑节点，具有接口层、高级处理层、基本服务层嵌套对象结构。根据一种广域保护算法，阐述基于多任务的保护代理与其他逻辑节点的协作流程和设计。研究位于不同变电站的保护代理之间点对点远程通信原理，分两阶段提交。协商消息以面向通用对象的变电站事件（GOOSE）等报文为基本内容，采用用户数据报协议（UDP）或传输控制协议（TCP）区分传输。广域后备保护代理模型在EPOCHS平台得到仿真实现和验证。     

基于EPOCHS的数字化变电站通信网络仿真分析

针对变电站自动化系统全站统一式通信网络结构,在电力通信同步仿真平台（EPOCHS）上建立了基于IEC 61850标准的数字化变电站的通信网络动态仿真模型。依据网络仿真需求,在网络模拟器NS2中实现了物理子网间的连接,并添加虚拟局域网多播和报文优先级处理机制。对采样值（SAV）和通用面向对象的变电站事件（GOOSE）传输的实时性进行了仿真分析,仿真结果为网络带宽、虚拟局域网划分以及报文优先级处理提供了依据。     

数字化变电站网络仿真平台探讨

通信网络设计是数字化变电站系统设计的核心内容之一，直接关系到数据传输的实时性和变电站各种功能的实现。文中提出了利用网络仿真平台对变电站通信网络进行设计的构想，分析了在数字化变电站不同的发展阶段，通信网络设计的主要内容和网络仿真平台的主要功能及意义，介绍了其结构和仿真流程，重点讨论了仿真模型、仿真内核、通信分析器等开发过程中需要解决的几个关键问题。     

基于IEC 61850标准的新型集中式IED

基于IEC 61850标准的变电站自动化是一种必然趋势。站级总线、过程总线的应用对间隔层智能电子设备（IED）网络接口的实时性、可靠性有很高要求，且数量众多的间隔层IED使变电站网络接线复杂。计算机技术的快速发展使硬件的集成度越来越高，可靠性大幅度提升，间隔层设备将会向集成一体化方向发展，使设计理念为面向变电站整体功能，有利于控制、保护功能的协调并大幅度减少IED数量。提出了一种遵循IEC 61850标准的间隔层新型集中式IED方案，在1台新型集中式IED上实现多台IED所完成的功能，分析研究了其硬件方案、软件结构及内部信息交换方式等关键技术，为实施基于IEC 61850标准的变电站自动化系统提供了一种新的解决方案。     

变电站通信网络实时性能仿真分析

采用动态仿真建模技术对变电站层嵌入式以太网的实时性能进行了详细分析。首先分析了报文端对端传递时延的构成，揭示了报文传输的本质;其次系统地分析了变电站中数据流的分布，根据统计特征建立了各类数据流的数学模型。考虑变电站通信网络数据流的分布特点和信息到达规律，采用动态仿真方法具体研究了变电站层嵌入式以太网的平均时延、最大时延等链路时延指标。最后进一步分析了TCP/IP协议的开销对报文端对端传递时延的影响。     

变电站过程CAN总线时延特性分析

过程总线替代二次电缆连接是变电站自动化技术未来发展的重要趋势。采用过程总线首先需定量分析信息在网络上传输的端对端时延，判断其能否满足变电站自动化功能对信息传输提出的实时性要求。文中分析了变电站过程总线数据流特征和控制器局域网（CAN）总线网络行为，综合考虑了网络传输时延和端系统处理时延对信息端对端时延的影响，建立了变电站过程CAN总线实时性能分析模型；借鉴实时调度的基本理论和分析方法，提出了任务和信息联合调度的方法，推导出了过程层CAN总线端对端时延的解析表达式，为定量分析系统性能提供了理论依据。     

分散式变电站监控系统中的通信技术方案

通过分析变电站内信息流向及流量，提出了适应站内通信系统的几种方案，并对其进行了 分析比较，特别 研究了总线型的通信系统实现方案，认为在目前阶段基于CAN总 线技术的通信系统具有优势。指出现场总线 技术必将应用于变电站自动化系统中，并需要 对传统的变电站按一次、二次划分的设计 观念进行更新，以 实现基于现场总线控制系统的一体化智能变电站。     

基于可信计算方法的变电站自动化远程通信设计

通过对安全功能执行点定位的分析，证明把安全功能执行点定位在智能电子设备（IED）符合IEC TC57无缝通信体系。针对这种安全需求，将可信计算组织（TCG）推出的可信计算方法引入变电站自动化中，在IED中种植可信平台模块（TPM）并建立信任链，采用远程过程调用（RPC）技术将信任关系扩展到远端，设计了一种安全远程通信平台，而报文的安全由公钥基础设施（PKI）或对称加密技术来保证。在此基础上，针对变电站远程控制的安全需求，结合变电站自动化控制操作的动作序列，设计了变电站自动化远程控制的安全通信体系。该设计能与IEC 61850，TCG等相关的最新国际标准保持一致，相关的密码算法遵循国家密码管理局的商用密码管理条例。     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

Impacts of Microcystis on algal biodiversity and use of new technology to remove Microcystis and dissolved nutrients

Cyanobacteria often dominate eutrophic lakes, outcompeting green algae that are required by fish and zooplankton. This study was undertaken to ascertain the impact of the cyanobacterium, Microcystis, on algal biodiversity. Under laboratory conditions, we found that the presence of Microcystis decreased phyla richness by 58%, phyla evenness by 47%, genera richness by 66% and genera evenness by 51%. Analysis by mixed anova s demonstrated a significant interaction between treatment and time and confirmed a significant reduction in richness and evenness of phyla and genera. We also conducted a phosphate restriction assay on the algae in Mason Lake (Irvine, CA, USA) and found that the threshold needed for algal growth there was 0.02 mg L^?1 PO₄. A pilot study was then conducted to test the effectiveness of the Blue Pro? water treatment facility in removal of this colonial organism from Mason Lake, in addition to removal of dissolved nutrients required for its growth. We measured a 97% reduction in Microcystis cells, a 72% reduction in chlorophyll‐a, and a 96% reduction in phosphate after just one 10 min cycle through the unit. Our study demonstrated that removal of Microcystis colonies may allow green algae to increase in numbers. This may improve algal biodiversity, which will benefit zooplankton and fishes.     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

簸箕李引黄灌区水沙分布及优化调度的经验

灌区利用水沙观测所取得的资料和试验数据，运用水沙运动力学理论，总结分析和揭示了灌区水沙分布的规律和特点。在此基础上，结合灌区的实际运行情况，围绕减少骨干渠道的淤积进行探讨、研究，进而，优化水沙调度方案。该方案实施后，骨干渠道减旅伴效果明显，取得了成功的经验。     

小湾水库大坝防渗面板及其裂缝的加固处理

小湾水库大坝防渗面板整体抗渗性能差,且存在多条裂缝,通过对面板钢丝网喷涂丙乳砂浆加固处理及其裂缝修补,大坝渗漏量明显减少,且左岸上灌浆廊道内及大坝下游坝面92～93 m高程下廊道入口处原有小股射流全部消失.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。