沙雅县枣树间作棉花滴灌

沙雅县农田灌溉采用高效节水灌溉方式,田间灌溉以滴灌为主,结合农作物种植式多采用红枣套种棉花,通过沙雅县托依堡镇枣树间作棉花滴灌项目的设计和实施,详细介绍了滴灌设计中的参数确定、滴灌带参数的选择、灌溉定额、管网的布置、水利计算等分析,为沙雅县其他乡(镇)推广枣树间作棉花种植提供重要技术依据和宝贵的经验。     

和田地区红枣套种洋葱滴灌技术效益及措施

在总结"特色林果业套种增效示范项目"实施基础上,探讨红枣套种洋葱滴灌技术在和田地区策勒县推广应用取得成效与遇到的主要问题。结果认为,红枣套种洋葱滴灌技术的应用在南疆地区是可行的,在不影响红枣产量和品质的前提下,间作洋葱不仅节约有限的水土资源,还可以增加农户收入,促进项目区内种植业的发展,也将为项目区农民脱贫致富做出积极贡献。     

滴灌工程设计中支管设计与选择探析

滴灌是一种高效的节水灌溉技术,能够大幅度提高水资源的利用效率,尤其是对于西部水资源相对匮乏的地区意义更加重要。支管设计作为滴灌工程设计的一部分,对于滴灌系统整体性能的发挥意义重大。文章在阐述滴灌系统中支管质量与检测标准的基础上,结合实际工程项目详细探讨有关支管的设计和选择措施。     

变径在棉花膜下滴灌中的巧妙运用

棉花膜下滴灌技术是根据棉花生长发育需求,通过滴灌系统湿润棉花根系层土壤的一种灌溉方法,该种灌溉方式不破坏土壤团粒结构,避免深层渗漏和地表流失,并且滴灌带铺设在膜下,水分和养分直接输送到作物根部,棵间蒸发大为减少,使作物对水、肥的有效利用率更高。该项技术不仅省水、省地、省肥,而且能够提高作物产量及产品品质,是今后发展精准农业不可缺少的核心灌溉技术之一。近几年来棉花膜下滴灌技术在农三师的农业发展中发挥了巨大效益,但如何近一步优化设计、降低投资和运行成本使该项技术能够大面积推广,已成为设计人员研究的重要课题。     

农田灌溉中滴灌系统的设计综述

在农田灌溉中,实施滴灌技术能防止水分因蒸发而造成流失,灌溉的水能使土壤表面湿润,采用滴灌方式对农作物进行浇灌时只对作物根部周围的土壤进行浇灌,而对其他地方的土壤浇灌的水量很少,这样能有效的抑制杂草生长。这种技术不会在地面上产生径流,浇灌的水量和深度能有效的得到控制,为此能更好的节约水资源。特别适合在水资源匮乏、气候干燥的地区使用。为了充分发挥滴灌系统的作用,需要科学的进行滴灌系统的设计。基于此,文章以实际工程为例,对滴灌系统工程的设计进行探讨。     

适用于庭院种植的微压微管滴灌系统试验研究

一般而言,常压滴灌灌溉效果较好,但系统成本相对较高,在我国贫困农村无法得到大面积推广;微压滴灌虽降低了成本,但时常灌水均匀度较低。针对该问题,将无泵恒定供水装置与悬挂式微管滴头应用于庭院式农田微压滴灌灌溉,其毛管入口端设计水头为0.35~0.55 m。试验结果表明：利用此微压微管滴灌系统,在不需水泵提供连续动力的情况下,能够为滴灌系统提供连续稳定的工作水头,且滴灌灌水均匀度达到95%以上。同时试验亦初步揭示了微压下该系统不同几何尺度微管滴头的水力性能与其结构参数之间的关系。     

地下滴灌毛管适宜埋深及间距研究进展

随着全球水资源的日益短缺,节水灌溉越来越引起人们的重视。地下滴灌是一种节水效率很高的节水灌溉技术,具有诸多优点。本文分析了地下滴灌毛管埋深和间距对作物生长和发育的影响,重点介绍了国内外地下滴灌毛管埋深和间距的研究进展及应用现状,对其发展历史、经济与环境效益、毛管埋深、毛管间距、作物的生长和发育及系统的投资等方面进行了综述,并对毛管埋深5 cm、15 cm和35 cm进行了土壤水分运移试验分析,以便为地下滴灌系统的合理设计提供理论依据。     

新疆春小麦滴灌系统的设计与实践

滴灌技术作为最高效的微灌技术,在新疆得到了广泛的应用,也产生了良好的经济效益。随着新疆生产建设兵团对种植结构的调整及减棉增粮政策的进一步实施,对主要粮食作物春小麦滴灌技术系统的研究具有重要意义。研究了新疆春小麦滴灌系统的组成、设计原则及主要设计参数的选定,通过试验初步得出新疆春小麦滴灌的灌溉定额,并进行了效益分析,经分析计算得出滴灌系统比地面灌溉可节约支出1 901元/hm2。     

滴灌史话

滴灌是以水滴形式向土壤供水，满足作物需水要求的先进灌溉方法。通常利用低压管道系统将水连同溶于水的化肥均匀而缓慢地滴进作物根部附近的土壤。 滴灌是由地下灌溉演变而来的。早在１８６０年，德国人将接头处开口的陶管埋在地下进行灌溉，这是人类有史以来最早的滴灌试验。现代滴灌的发明者是以色列工程师Ｓ·布莱斯。１９３０年，布莱斯从水龙头滴水现象受到启发。产生了用小水量灌溉的设想，于是他设计了一种能够间隔对作物根系放出小水量的低压灌溉设备，并取得了专利。之后，布莱斯又对这项技术进行了改进，在地表沿着植株安放小直…     

浅谈滴灌系统的优缺点

由于受气候因素的影响,黑龙江省已连续几年发生了严重干旱。而解决干旱问题的最有效途径就是大力发展节水灌溉,在干旱气候条件下,要使种植的作物优质高产,灌溉是至关重要的,即使在半干旱和半湿润条件下的季节性干旱期内,补充灌溉对于作物优质高产也同样至关重要,灌溉可以为作物获得最佳产量和最优产品提供充足的水分。近几年,节水灌溉在黑龙江省发展迅速,尤其是滴灌系统在棚室蔬菜种植中被越来越多的应用。在应用过程中,认识滴灌系统的优缺点尤为重要。     

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。     

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.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

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.     

浅谈天湖水电站水轮机运行故障及处理措施

简述天湖水电站投运以来各种故障的表现形式，分析其原因，提出了相应的处理方法及措施，并对合理利用国内外设备提出建议。