Improving fishery-independent indices of abundance for a migratory walleye population

The primary goal of many biological surveys is to provide an unbiased representation of trends of population abundance. However, there are often factors other than abundance that vary over time and influence catch rates and thus inferences about population trends from surveys. This is particularly true for highly mobile species because of interannual variation in the timing, extent, and duration of movements, and for surveys that are not randomized with respect to space and time. We developed general and generalized linear mixed models to standardize Canadian and United States fishery-independent surveys that provide an index of basin-level walleye (Sander vitreus) population abundance trends in Lake Erie (1983–2008). In Canadian waters, the probability of a non-zero catch was associated with the type of gill net set (canned > bottom sets), the presence of hypoxia (negative trend; −), and secchi depth (−). Positive catch rates were associated with the set type (canned > bottom) and water depth (+). In United States waters, survey catch rates were associated with secchi depth (−) and surface water temperature (+). For each case, the best model included random effects (interactions between year, week, basin, sub-basin) which accounted for a modest amount of the total variation. General abundance trends were similar between the standardized and nominal indices, but substantial annual variation in the direction and magnitude of the difference between indices was observed. We recommend the use of standardized indices for walleye population assessments because these account for factors influencing catch rates other than changes in abundance.     

Improving bio‐diagnostic monitoring using simple combinations of standard biotic indices

Invertebrate biotic indices are used widely to assess river quality. However, because reduced values can have many potential causes, general biotic indices have limited value in diagnosing reasons for impairment. Here, we investigate whether simple combinations of biotic indices can improve diagnostic capability. In the catchment of the Welsh River Wye, invertebrates varied significantly among groups of 55 streams in taxonomic composition and in index scores representing acidification (AWIC), mild eutrophication/organic pollution (BMWP/ASPT), and flow (LIFE). Although sites impacted by different forms of pollution tended to have reduced BMWP scores, acidified and enriched sites became distinguishable from each other, and from unimpaired streams, when classified on a combination of these indices. Combined indices also differentiated among competing explanations for trends in biological quality through time by revealing how increasing BMWP at some sites reflected local reductions in eutrophication. These data illustrate how simple univariate indices, calibrated to respond to specific pressures, have bio‐diagnostic capability when used together even in a relatively unpolluted catchment such at the Wye. In this Special Area of Conservation, they identified specific management needs in different locations—respectively to mitigate acidification in upland base‐poor tributaries and to reduce diffuse nutrients in the lower catchment. We advocate (i) the development of more pressure‐specific indices, for example to detect morphological modification, sedimentation and metal impacts; and (ii) further exploration of combined indices from one or more groups of organisms (e.g., diatoms and invertebrates) to increase bio‐diagnostic capability in river monitoring. Copyright © 2008 John Wiley & Sons, Ltd.     

住宅建筑户内热水系统循环设置

1 目前家用燃气热水器存在的问题 家庭户内采用的热水器主要是燃气热水器(容积式燃气热水器或即热式燃气热水器)和电热水器两大类.根据现行市场上居民用天燃气和电的价格来看,燃气热水器比电热水器更经济实惠,所以大多数家庭都是选择燃气热水器作为家庭的热水制备设备.     

住宅卫生间同层排水设计新尝试

同层排水是指卫生间内卫生器具排水支管、横管不穿越楼板且排水横管敷设在本楼层结构降板空间内的排水管道的布置方式,充分体现了“以人为本”的设计理念,是当今住宅给排水设计的发展趋势。针对已有同层排水方式的作法,提出了在同层排水的下沉空间内设置地沟、检修盖板的想法,并介绍了在工程中的实际应用。     

海啸波引起的近岸房屋局部冲刷试验

基于波浪水槽,分别考虑独栋和房屋群两种情况,开展海啸波引起的近岸房屋局部冲刷试验研究,分别建立了独栋房屋情况下相对最大冲刷深度与海啸波相对越顶高度关系式和房屋群情况下局部最大冲刷深度与海啸波波高、房屋宽度、房屋高度、房屋数量、房屋间的中心间距的关系式。试验结果表明在海啸波越顶水流产生的水跌以及海啸波通过房屋时产生的扰流共同作用下,房屋周围,特别是海侧会产生明显的局部冲刷坑;回落水流水跌是局部冲刷坑产生的主要因素,扰流是次要因素。所建立的关系式揭示了最大局部冲刷深度与海啸波、房屋尺寸、房屋布局的内在联系。     

居民平均日热水用量研究与分析

通过总结大量住宅热水用量的实态调查数据和参照国外调研资料,分析了设计太阳能热水系统集热面积的关键技术参数——居民平均日热水用量。建议在采用局部热水供应系统时,居民平均日热水用量取30~40L/(人·d);采用集中热水供应系统时,居民平均日热水用量取45~60L/(人·d)。     

住宅厨卫排水横管降板同层安装简介

介绍了住宅厨卫排水横管降板同层安装的构造、优缺点,及其与传统卫生间排水横管隔层安装的比较等.以山西省万家寨引黄工程管理局汇锦底商高层住宅楼为例,对其厨卫排水横管降板同层安装施工工艺进行阐述.     

住宅给水设计流量简化计算的探讨

剖析了《建筑给水排水设计规范》(GB5 0 0 15 - 2 0 0 3)第 3 6 4条住宅建筑生活给水设计流量的计算方法 ,提出了与住宅卫生设备设置水平相适应的人均占有当量数的概念和给水设计流量的简易计算公式。并对简易计算公式与规范计算方法的相对误差进行了验算 ,证明了简易计算公式的可行性。为方便设计使用 ,以规范规定的用水定额与对应的小时变化系数乘积的平均值为基础 ,对A ,B ,C1,C2 四种不同人均占有当量 ,用简易计算公式计算得不同当量数的设计流量 ,绘制了住宅给水流量计算图表。     

斜向和多向波浪的破碎指标研究

该文通过水池物理模型实验,研究了在1:15的斜坡条件下斜向和多向波浪中破碎的特点。根据波浪类型和岸坡条件将破碎指标分为四类,总结了每一类破碎指标公式的通用形式和系数。对实验中正向和斜向规则波、正向和斜向不规则波、正向和多向不规则波的破碎指标进行了比较和分析。研究结果表明:同等条件下,斜向波的破碎指标较正向波偏大,基于不规则波有效波高的破碎指标小于规则波的,而多向波在波高较大时的破碎波高与正向不规则波相比偏小。     

黄河下游高含沙洪水河床形态及调控指标

利用水库调控高含沙洪水是维持黄河下游主槽不萎缩的重要途径。基于黄河下游实测高含沙洪水冲淤特性的分析,按流量大小对高含沙洪水进行了分类,提出了黄河下游高含沙洪水的分类调控思路及相应的调控指标。大漫滩高含沙洪水,在满足黄河下游防洪要求的前提下,控制洪峰流量大于1.5倍的平滩流量,来沙系数在0.012~0.04 kg·s/m~6范围内。一般高含沙洪水,控制黄河下游洪水流量接近平滩流量,并尽可能控制来沙系数在临界值附近。高含沙小洪水,控制黄河下游洪水流量在2 500 m~3/s以下,洪水沙量小于2亿t。高含沙洪水经过分类调控后,可较大限度地利用滩地淤沙、主槽输沙能力排沙及花园口以上较大的主槽库容滞沙,维持或提高黄河下游主槽过流能力。     

社区尺度居民楼内涝淹没过程精细化模拟及室内财产损失评估

以西安一小区居民楼为研究对象,构建了高精度城市雨洪模型,并通过实测暴雨内涝监测数据验证了模型的可靠性;利用构建的模型模拟了6种设计降雨重现期下的居民楼室内动态淹没过程,并以西安市中等收入家庭的房屋配置为计算单元,分析了各类居民室内财产的淹没水深阈值,依此拟合得到了室内财产淹没水深-损失率关系曲线,结合居民楼在不同降雨重现期下的淹没水深,计算得到了各居民楼在不同降雨重现期下的内涝淹没财产损失数据。结果表明：不同降雨重现期下,同一居民楼一层居民房屋室内进水淹没水深随降雨重现期的增大而增大;同一降雨重现期下,各栋居民楼因高程不一致导致内涝淹没过程及最大淹没水深不一样。     

Method of evaluating the effect of reservoir siltation on hydrostation indices

Conclusions  

太阳能二次换热集中供热系统设计方案

介绍了一种太阳能二次换热集中供热系统。由于采用了二次循环系统,流经集热器的是介质,从而可以方便地在介质中加防腐、防垢和防冻剂,较好地解决了系统的防腐、防冻、防垢问题。系统采用具有综合功能的智能控制器,以解决全天候问题。避免了各用户单位单独运行、维护、管理,提高了供水的可靠性。并指出了该系统实施中存在的其他问题。