关口水电站双室式压力前池设计

山区性河流上修建径流引水式水电站，面临泥沙问题，泥沙对水工建筑物的影响和对水轮机的严重磨损，使汽蚀现象加剧。该文着重以关口水电站压力前池的设计为例，讨论了如何有效地防止泥沙进入压力管，从而减少因泥沙而造成的损失。     

大流量漏斗沉沙池体型优化研究

为处理好大流量漏斗式沉沙池的沉沙与排沙问题,研究较合适的沉沙及排沙体型,以大盈江漏斗沉沙池为例,研究了沉沙池整体流场,通过整流墩使工作段达到"静水"沉沙的流态.沉沙及冲沙的实验表明:有害粒组的沉降保证率大于80%.排沙孔口进一步优化后,排沙量与沉沙量达到平衡时,池内淤沙不影响沉沙池正常运行.漏斗式沉沙配合8条廊道冲沙的体型满足大流量沉沙池的要求.研发了一个基本解决大流量沉沙池的沉沙排沙问题的体型,为后续的体型研发工作提供了一条思路.     

沉降剂控制热雾机热雾滴扩散范围及防效的研究

热雾机一般以柴油为热雾剂承载农药,形成的热雾喷出后随着喷口产生的动力和热雾的自身密度压差向前方自行推进,该施药技术由于效率高而广泛用于林业病虫害的防治。但由于热雾易飘移、难控制,造成农药污染的缺陷,在农作物生产中难以推广应用。本试验通过加入热雾沉降剂的方法,加大了热雾机热雾滴的比重和沉降速度,在此基础上,选择难以进入田间施药的玉米、油菜,进行了中、后期病害的防治试验,结果表明：加入热雾沉降剂后热雾滴的主体分布于田间水平距离(0~25 m)和垂直高度(0~2 m)范围内,分布密度为148.5~265.4粒/cm2,同柴油对照相比,加入热雾沉降剂后,同等直径的热雾滴飘移的距离和高度明显降低。田间防治试验结果也表明,热雾机施药对油菜菌核病和玉米南方锈病的防治效果普遍高于机动弥雾机喷雾的防治效果,加入热雾沉降剂后可提高有效防治范围内的防效。     

小麦品种间籽粒品质性状表现及其相关性分析

以125个普通小麦品种(系)为试材,分析了它们的籽粒硬度、蛋白质含量、湿面筋含量和Zeleny沉降值表现及4项品质指标的相关性。结果表明:硬度与蛋白质含量、湿面筋含量、沉降值均呈极显著正相关,蛋白质和湿面筋含量也分别与沉降值呈极显著正相关,而蛋白质含量与湿面筋含量间相关不显著。将被测品种按面筋强度分为强、中、中下和弱4个等级,不同的等级中,各性状的相关性又产生了很大的差异。此外,各品种小麦硬度的变幅是7 5%～81 4%,变异系数为33 71%;蛋白质含量的变幅是9 9%～16 9%,变异系数为9 39%;湿面筋含量的变幅是3 6%～93 2%,变异系数为62 28%;沉降值的变幅是16 5～51 7ml,变异系数为27 93%。这些品种中多数为硬质麦,蛋白质含量中等,湿面筋含量较高,但也有部分材料湿面筋含量非常低,沉降值中等偏低。     

Physical Characteristics of Commercial Pelleted Atlantic Salmon Feeds and Consideration of Implications for Modeling of Waste Dispersion through Sedimentation

Models used to employ waste dispersion from sea cages rarely take into account the physical characteristics of fish feed and faeces. In this study we determine the hardness, friability, water absorption properties and settling velocity of a range of commercial Atlantic salmon (Salmo salar L.) feeds, under defined laboratory conditions.Hardness of large, high energy pellets ( 8.5 mm) was generally greater than that of 6 mm high energy pellets. With the exception of 100 mm pellets, the friability of large pellets was also greater than that of the smaller pellets. Settling velocities were significantly greater at 20 psu than at 33 psu and significantly higher for most pellet types at 10 °C than at 20 °C. Settling velocities for unsoaked pellets were found to increase with pellet size, from a mean of 5.6 cm s^–1 for the smallest pellet (2 mm) to 13.9 cm s^–1 for the 10 mm standard (20 to 24% fat) pellets. The smallest feed pellets (2 mm) had the greatest percentage wet weight increase on immersion, irrespective of salinity. Settling velocities of pellets were not significantly affected by immersion time (0–15 min).Given the water depths at fish cage sites and the settling times involved, it is concluded that it is unnecessary to take account of changes in food pellet settling velocity as a result of immersion. Effects of pellet size and salinity on settling velocity are best incorporated into waste dispersion models through the use of 'look-up' tables.     

Abiotic and biotic associations between the round goby Neogobius melanostomus and tubenose goby Proterorhinus marmoratus with the endangered northern madtom Noturus stigmosus in Canada

1. Quantifying habitat associations and threats to the persistence of imperilled species is a fundamental step for initiating species recovery efforts, but the traits associated with species imperillment (e.g. rarity and vulnerability to stressors) also limit the ability to empirically inform recovery strategies. Novel sampling designs and modelling approaches are therefore needed to quantitatively assess habitat associations and the threats to species persistence.
2. To improve the understanding of habitat associations and threats for one of the rarest endangered freshwater fish species in Canada, northern madtom (Noturus stigmosus), two‐species occupancy models were developed with two invasive gobies: round goby (Neogobius melanostomus) and tubenose goby (Proterorhinus marmoratus). Models were parameterized with data from a multi‐year benthic trawling survey of two large Great Lakes tributaries in southern Ontario, Canada, and subsequently used to evaluate the need for reducing measurement error with future sampling efforts.
3. The probability of detecting northern madtom in the St. Clair (0.163) and Thames (0.194) rivers was low compared with round goby (St. Clair, 0.827; Thames, 0.833) and tubenose goby (St. Clair, 0.297). The best occupancy models indicated a negative association between northern madtom and round goby in the St. Clair River and the importance of gravel substrate for northern madtom.
4. Up to 16 repeated non‐detections using benthic trawls are needed to be 95% confident that northern madtom is absent at a site, indicating that current sampling approaches are likely inadequate.
5. Despite low detection probabilities, intensive trawling surveys combined with the two‐species occupancy modelling framework provided vital information for describing habitat associations for northern madtom and identified a significant negative association with round goby. Nonetheless, alternative sampling methods to improve the detection probability of northern madtom would allow a more robust evaluation of habitat associations and would provide more information on the negative association with round goby.

     

林区公路改扩建中路基加宽防变处置

以省道S204线将乐段孙坊至铁岭公路(孙铁公路)改扩建加宽工程为例,分析林区公路改扩建中加宽路基结合部产生沉降变形的主要原因,并提出基底加固、开挖台阶和土工织物应用以及填筑压实等处置对策。     

High-Speed Railway CFG Pile Composite Foundation Settlement Influence Factors Analysis

Because of high bearing capacity and small settlement of CFG pile, CFG pile have been used widely in foundation treatment of engineering construction, but it has applicant in high-speed railway roadbed only in the initial stage. In this paper, based on the project of Beishahe of Hada high-speed rail, simulated with the finite element model by ADINA by changing the parameters of CFG pile and roadbed height in the situation of permafrost and unpermafrost of foundation, obtained the relationship of parameters and foundation settlement, it has the directive significance for high-speed railway with CFG pile composite foundation.     

碱性含油污水生化处理的实验室研究

介绍采用厌氧酸化－好氧活性污泥法处理碱性含油污水的实验室研究情况。研究结果表明，采用生物酸化可以调整污水ｐＨ值，并可提高可生化性，使整个系统的ＣＯＤ去除率提高，从而可以认为生物（水解）酸化－二级暴气沉淀是炼油含碱污水合适的生化处理流程。     

Human modification of stream valleys in the western plateau of São Paulo,Brazil: implications for environmental narratives and management

Deforestation, agricultural land uses and urbanization have altered stream channels and floodplains in many regions of the world, yet occurrences of post‐settlement alluvium (PSA) and benchmark pre‐settlement horizons (Palaeosols) are unreported in many tropical and subtropical developing countries. Twentieth century land uses, motivated strongly by state subsidies in the cases of coffee and cotton cultivation and soy – wheat double cropping, caused soil erosion and the corresponding formation of PSA and stream‐channel changes in small catchments of the Western Plateau of São Paulo State, Brazil. Analysis of land‐use changes suggests necessary alteration of regional environmental management for restoration planning, water quality monitoring and control of gully erosion. Narratives of regional environmental change should address the impacts of agropastoral land uses on soil and water resources, rather than concentrating on deforestation and forest land cover. Copyright © 2000 John Wiley & Sons, Ltd.