特殊配电网接线故障定位和隔离的改进算法

配电网系统中，在向专线用户或综合负荷供电的分支馈线与主干馈线交接处，常装有特殊形式的隔离开关。针对这种实际情况，目前基于变结构耗散网络理论的故障定位和隔离算法存在无谓扩大故障切除区域的问题。通过引入虚拟开关概念，对上述特殊形式的隔离开关进行建模，并在此基础上提出了基于变结构耗散网络理论的故障定位和隔离改进算法。算例分析表明，该改进算法可以充分发挥此类特殊形式隔离开关的操作灵活性，从而实现故障定位及隔离的最小化。     

配电网故障判断与负荷均衡化

提出一种配电网简化模型：将馈线开关当做节点，将馈线当做弧，从负荷的角度描述配电网，并采用邻接表的数据结构加以描述。在此基础上发展了配电网故障区域判断方法，讨论了以最少的开关操作隔离故障区域的方法。提出一种以联络开关为核心的用于负荷均衡化的配电网络重构方法，将每个联络开关对应的两条馈线看做馈线偶，分别定义了馈线偶和配电网的负荷均衡率，并以此作为网络重构的评价函数，配电网络重构过程由若干馈线偶内负荷均衡化过程组成，这种方法具有迭代次数少和不需要量测馈线配电变压器参数等优点。文中给出了典型实例。     

基于最短路的复杂配电网可靠性评估分块算法

配电网具有闭环设计、开环运行、网络中配置的开关相对较少的特点。基于该特点，应用最短路方法和分块技术提出大规模复杂配电网可靠性评估算法。给出配电网馈线末端节点、边界节点的定义以及块的定义和性质。基于最短路提出配电网分块形成算法，进而提出配电网可靠性评估算法。故障模拟时，文中方法以“块”为单位代替常规方法以“元件”为单位进行分析，利用最短路法确定开关元件的影响范围，节省了大量重复的开关元件搜索时间。应用该算法对RBTS及大量实际工程系统进行了可靠性评估，算例表明该算法具有高效性和工程实用性。     

配电网故障区间判断的新型矩阵算法

针对配电网故障区间的判断问题，利用配电网的结构和运行特点，提出将馈线作为树或有向图来描述，并构造了基于开关和双亲表示法的馈线有向描述模型。在此模型基础上，结合故障信息矩阵建立了一种配电网故障区间判断的新型矩阵算法。通过对该算法适用性的讨论，扩展了其对多电源网络的处理能力，算例证明该算法对单重故障是很有效的。同时，该文也探讨了其在多重故障模式下的解算能力，虽然有一定的局限性，但通过仿真表明很多情况下还是有效的。     

基于故障扩散的复杂中压配电系统可靠性评估算法

提出一种中压配电系统可靠性评估算法。该算法对复杂的中压配电系统(带子馈线)有较强的处理能力，利用前向搜索算法确定断路器动作影响范围，用故障扩散方法确定故障隔离的范围，从而确定节点的故障类型。根据故障的类型，便可形成相应的节点、馈线以及系统的可靠性指标。以RBTS-Bus6，RBTS-Bus2等配电网络和大量实际运行网络验证了该方法的有效性和实用性。     

配电网馈线末端故障定位优化算法

提出了一种能解决配电网馈线末端故障定位、并适用于多电源复杂网络故障定位的优化算法。根据网络拓扑结构和假定的正方向建立网络描述矩阵，由馈线终端单元（FTU）获得的故障过电流及其方向信息组成信息矩阵，结合网络描述矩阵对信息矩阵进行修正得到信息判断矩阵，由信息判断矩阵可以直接判别出故障区域。     

基于GPRS的配电网馈线自动化模式的探讨

针对配电网自动化通信系统对数据传输可靠性和实时性的要求，提出了一种基于通用分组无线电业务（GPRS）的配电网馈线自动化通信系统设计。通过对几种馈线自动化故障处理模式的比较和分析，提出了数字式保护与分段开关配合，经GPRS传输信息实现远方综合故障判断、处理模式的方案，阐述了该方案的优越性、先进性和实用性。     

基于最小路法的配电网可靠性评估研究

在对配电系统的可靠性指标及模型深入研究的基础上,提出一种基于最小路等值的配电系统可靠性评估算法。该算法考虑了分支线保护、隔离开关、分段断路器的影响,并且能够处理有无备用电源和有无备用变压器的情况。实例计算结果表明,该方法简单方便、通用性强,可以很好地应用于配电网可靠性评估。     

基于最小路法的配电网可靠性评估研究

在对配电系统的可靠性指标及模型深入研究的基础上,提出一种基于最小路等值的配电系统可靠性评估算法。该算法考虑了分支线保护、隔离开关、分段断路器的影响,并且能够处理有无备用电源和有无备用变压器的情况。实例计算结果表明,该方法简单方便、通用性强,可以很好地应用于配电网可靠性评估。     

基于网络化简的计及开关故障配电网可靠性评估

提出一种基于区域网络（区域元件）的等效网络,并将其用于配电系统可靠性评估。该方法 以各类开关为边界,根据区域边界开关手动或自动性质的不同,定义了2种区域元件,并组成相应 的用于系统可靠性指标评估的2类等效网络;提出了对等效网络进行化简的有效命题;通过将开关 故障的影响计入区域元件中,避免对开关故障单独考虑,在以区域负荷为评估对象以及区域元件为 分析单元的基础上,对等效网络采用分级评估的策略,从而减少了遍历及分析单元的数目,也避免 了同类负荷点的重复遍历。算例表明,与现有方法相比,文中算法具有更高的计算效率。     

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。     

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.     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.     

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。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.