温室蔬菜微灌技术

微灌,即微量灌溉。温室蔬菜微灌技术,是对我国北方广泛采用的温室栽培蔬菜进行科学灌溉的节水、节能、增产、增收的先进灌水方法和灌溉技术。 温室蔬菜微灌技术与传统的沟、畦灌水方法的根本区别,是它利用微灌系统,将低压水直接输送到蔬菜根部或喷洒在枝叶上,使适量的灌水及时、均匀、缓慢地渗入土壤中,以消除传统灌水方法的水流对耕层土壤的冲刷和压实作用,且因严格控制灌水量而可杜绝深层渗漏。从而使之较沟、畦灌水方法具有明显的保土、保肥、保持地温等作用,并为耕作     

科技信息

温泉乡果树小管出流环沟灌溉法 果树小管出流环沟灌溉法,是在原有微灌设备基础上实施的一种节水、抗堵塞的局部灌溉方法。该方法施工、操作简单,适应性强,适于灌溉果树、蔬菜。经水利部等有关专     

果园半固定穴式渗灌技术介绍

半固定穴式渗灌技术是现有固定式果园微灌技术基础上，根据农村果园管理现状和微灌技术设备情况，对灌水器和灌溉管理作以改进而发展起来的一种局部灌溉方法，具有投资省，见效快，便于推广等优点，是一套集灌水，施肥药于一体的实用性微灌技术，具有推广价值。     

农业节水抗旱技术简介

1　节水灌溉技术a.田间地面灌水。改土渠为防渗渠输水灌溉,可节水20%左右。在习惯大水漫灌或大畦大沟灌溉的地方,改宽、长畦为窄、短畦,改长沟为短沟。b.管灌。利用低压管道将灌溉水直接输送到田间。该技术具有投资少、节水、省工、节地和省能耗等特点。与土渠输水灌溉相比,管灌可节水30%～50%。c.微灌。有微喷灌、滴灌、渗灌及微管灌等,将灌水加压、过滤,经各级管道和灌水器具灌水于作物根际附近。微灌属于局部灌溉,只湿润部分土壤。微灌技术与地面灌溉相比,可节水80%～85%。微灌可以与施肥结合,利用施肥器将可溶性肥料随水施入作物根区,及…     

我国北方地区微灌节水技术

微灌技术具有省水、省工、节能、灌水均匀、利于作物优质高产等特点。我国北方的山东、河北、甘肃、辽宁等省开展微灌技术试点，经济效益显著。对于不宜采用地面灌溉适合微灌技术的作物其效益更为明显．微灌技术的核心是灌溉制度的确定，即准确的计算全年灌水量、灌水周期、一次灌水延续时间。灌水次数和全生育期灌水总量是微灌技术的关键。     

温泉乡果树小管出流环沟灌溉法

果树小管出流环沟灌溉法是在原有微灌设备基础上实施的一种节水、抗堵塞的局部灌溉方法。本文介绍了该系统的设计、施工和经济效益分析。     

果园半固定穴式渗灌技术介绍

半固定穴式渗灌技术是在现有固定式果园微灌技术基础上,根据农村果园管理现状和微灌技术设备情况,对灌水器和灌溉管理作以改进而发展起来的一种局部灌溉方法,具有投资省、见效快、易管理、便于推广等优点,是一套集灌水,施肥药于一体的实用性微灌技术,具有推广价值。     

以色列节水灌溉考查报告

以色列的全部灌溉面积均为喷、微灌。除个别边远山区外，实现了全部输、配水管道化，除给水栓外，管道全部埋于地下。管道虽投资高，但消除了输、配水过程中的水量损失，节省占地，为水管理创造了良好条件。水管理已普及了计算机，集中管理，自动控制。田间灌水小区，安设灌溉控制器。田间灌溉不需要人。以色列微灌技术发展较快，并有逐渐替代喷灌的趋势。其原因是微灌技术较成熟，主要表现：１、生产世界最先进的过滤设备。有沙过滤器，网过滤器，旋流式水沙分离器，叠片式过滤器。２、微灌灌水器种类多，并已系列化。３、微灌配套设备已定型和系列化。节水灌溉技术在以色列得到广泛应用的主要原因：１、缺水且必须灌溉，灌溉是农业的基础。２、水费昂贵。３、高效益出口农业，经济上有能力支付灌溉设备的高投入。（孟淑娴）     

浅谈改进地面灌溉技术

地面灌溉是最古老且历史悠久的灌溉方式,与喷灌、微灌相比,该方法具有投资少、能耗及运行费用低、田间工程简单、操作方便、运行管理方便等优点。但传统的地面灌溉方法技术落后,田间工程占地多,管理粗放,沟、畦规格不合理,水量浪费严重。因此,改进地面灌溉技术,提高灌水效率,节约灌溉用水已成为我国农田灌溉的重要任务。     

滴灌在日光温室中的应用

滴灌技术是微灌技术的一种类型，微灌技术主要包括滴灌、微喷灌、脉冲微喷灌、渗灌等。随着当前农业科学的发展，各种类型的节水灌溉技术也应运而生。我国大棚温室多采用传统的沟畦灌，水的利用率只有４０％。进入９０年代，国家对节水灌溉日益重视，投入相对增加，促进了微灌技术的广泛应用。海伦市实施了国家级节水增效灌溉示范项目，温室采用微灌，以滴灌为主，水利用率最高达９５％。 蔬菜保护地采用滴灌技术，不仅节约灌溉用水，同时还为蔬菜生长发育创造了适宜的水、肥、气、热、光等生态环境，为增产创造有利条件。 一、硬管滴灌植株…     

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。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

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.