European eel distribution and body condition in a river floodplain: effect of longitudinal and lateral connectivity

Abstract – We studied eel population characteristics (size classes, densities and body condition) in the lower Loire River floodplain (France) to evaluate the effects of longitudinal and lateral gradients. A total of 36 sites were electrofished in June 2005. The sites were grouped first into three river segments according to the distance inland corresponding to a longitudinal gradient and secondly into three lateral connectivity categories. Results indicate that small eels, especially those ≤300 mm, were very abundant downstream but density rapidly decreased upstream. In addition, eels ≤150 mm tended to be most abundant in connected waterbodies. Conversely, the distribution of larger eels was quite uniform across both dimensions. Eel condition decreased upstream. In parallel, in downstream river segment, eels had a lower condition in disconnected waterbodies than in connected ones. Eel specialists still have only a longitudinal perception of eel habitat. Our results suggest that lateral gradients should be also taken into consideration.     

Association of brook trout and Oncorhynchus spp. with large wood jams in a Lake Superior tributary in a northern old‐growth watershed

Wood in streams functions as fish habitat, but relationships between fish abundance (or size) and large wood in streams are not consistent. One possible reason for variable relationships between fish and wood in streams is that the association of fish with wood habitat may depend on ecological context such as large‐scale geomorphology. We studied the relationship between salmonid assemblages and large wood jams (LWJ) in four settings that differed geomorphically at the scale of the stream corridor along a tributary to Lake Superior in old‐growth conifer–hardwood forest in northern Michigan. The focal fish species of this study were brook trout (Salvelinus fontinalis), which were wild in the stream. Relocation efforts for coaster brook trout (an adfluvial life history variant of brook trout) were ongoing in the study stream. We measured fish abundance and length in pairs of pools of similar size and substrate, but varying in the presence of LWJ; this allowed us to evaluate associations of fish simply with the presence of LWJ rather than with other channel or flow‐shaping functions of LWJ. The length of Oncorhynchus spp. and young introduced brook trout was not strongly correlated with LWJ presence; however, the presence of LWJ in pools was positively correlated with larger wild brook trout. We also found that the correspondence of LWJ with the abundance of salmonids appears to be moderated by the presence of alternative habitat in this relatively natural, old‐growth forest stream.     

管道工程环境与力学行为

长输管道所处的环境比较复杂，主要包括所输送介质的环境，运行操作环境、管道周边环境、沿线自然环境与灾害环境以及管道的施工制造环境。在这些环境的作用下，管道将产生相应的力学行为，主要有承载行为，变形行为，断裂行为，疲劳行为和腐蚀行为，为保证管道工程的经济合理性，使管道长期平稳运行，就要在设计阶段将管道所处环境与相应产生的力学行为有机地结合起来，从这一角度出发，提出合理选择线路，正确选用选材，腐蚀控制、管道保护、施工控制和管理维护等6项措施。     

库鄯输油管道自动化系统

介绍了库鄯输油管道的ＳＣＡＤＡ系统的配置以及该系统所彩和的ＯＡＳＹＳ５．２系统软件的结构，特点与应用，ＯＡＳＹＳ５．２５系统具有良好的界面，能很好地与其它软件兼容。应用该系统可实现全线的启停高度自动化，在自动化管理方面达到了世界管道的先进水平。     

管道线路工程中的水工保护

水工保护是管道建设中的一个重要环节，但由于对其认识和重视程度不够，每年汛期，管道都会不同程度地出现一些水害问题，分析了管道遭受水害的一些基本现象及原因，提出了一些常用的水工保护措施。     

苏丹混合原油加剂常温输送工艺研究

对苏丹输油管道的加剂常温输送工艺进行了研究,介绍了苏丹混合原油降凝剂的研制开发、分析了加剂苏丹混合原油流变性和模拟技术以及结蜡规律,在借鉴已有的应用加剂综合处理输送技术的基础上,成功地将该项技术应用于苏丹外输管道,该项技术的应用,减少了一次性管道建设的投资,节省了大量的燃油费,取得了良好的经济效益.     

热油管道在水下隧道施工中应注意的问题

结合魏荆输油管道唐白河穿越段水下隧道改造工程,综合分析了热油管道在水下隧道穿越施工中的安全性、热力性和敷设方式的可行性, 指出热油管道采用水下隧道穿越方式具有安全性高、散热损失小、可满足管道在温差变形作用下的安全运行等特点.     

华南地区高大平房仓综合控温模式试验

根据华南地区生态条件,通过高温期间开展空调调节仓温等综合控温措施,基本实现了低温、低药量保粮,延缓了储粮品质劣变并抑制了虫霉活动。     

估测木薯茎叶生物量的一数学模型

为构建木薯茎叶生物量的估测模型,调查了木薯上、中、下部的茎粗、株高、叶柄长等形态学指标与茎叶生物量的关系.结果表明,木薯茎叶生物量主要受下部茎粗和株高的综合影响,并且下部茎粗、株高与茎叶生物量的关系均为乘幂函数关系.通过模型拟合和择优得到木薯茎叶生物量的估测模型W=0.032 83d2.48 6h0.1824.经新的实测数据检验,理论值与实测值的相对误差率为4.46%,完全满足测量精度要求.     

中小型圆柱形钢油罐直径和高度的计算方法

从实际计算出发，将等壁厚油罐和变壁厚油罐统一考虑，得到了最省材料的中小型油罐的高度确定方法。计算表明，油罐的最优高度不但与钢材种类，焊接水平，顶底厚度之和有关，而且还与所设计油罐的圈板数（或圈板高度），最小壁厚、液面蒸气压等有关。用原有方法确定油罐高度有些偏大。地公称容积同但计算容积不同的油罐，其设计高度应有所区别。