PLC及变频调速恒压喷灌系统的设计     

刘永华  陈志明  王念春 《节水灌溉》2009,(1)

针对喷灌系统受作业区域需水量的影响造成系统喷头不能稳定可靠工作的问题,结合工程实例,提出了利用PLC及变频器来实现温室喷灌系统恒压供水.给出了变频调速恒压供水系统原理图,并进行了系统的主电路设计和软件设计.阐述了利用上位机、PIC、变频器、压力变送器、电机-水泵系统等组成的恒压供水系统,能按照设定的工作压力,实时切换泵组投入工频或变频状态运行,达到恒压供水的目的.系统能通过上位机实现下位机的控制参数的设定、系统的实时监测、数据管理等任务,自动化程度高.应用表明,系统实现简单,操作方便,运行稳定,可靠,且具有较好的节能效果.  相似文献   

复杂注水系统泵站优化调度的改进遗传算法   总被引：1，自引：0，他引：1  

杨建军  战红  丁玉成 《节水灌溉》2009,(7)

以耗电量最小为目标函数,排量、压力等限制为约束条件,建立了复杂注水系统泵站优化调度数学模型.针对系统运行特点,采用改进遗传算法对模型进行求解,同时优化出泵的运行状态和排量.改进遗传算法采用实数编码,并设计了随机多父辈交叉方法,改进了变异操作,操作过程中,给出了泵排量的处理方法,使各水量约束条件得到满足,大大减少了不可行解的产生,使算法的优化性能得到了提高.算例说明了该优化方法的有效性.  相似文献   

基于层次分析法的节水型社会评价研究   总被引：1，自引：0，他引：1  

徐海洋  杜明侠  张大鹏  潘乐  姚宛艳  韩栋 《节水灌溉》2009,(7)

以郑州市为例,根据实际情况,建立了节水型社会定量评价指标体系,采用层次分析方法对建立的评价指标体系做了评价,计算得出,2010年将初步建立节水型社会,2020年将全面建成与小康社会相适应的节水型社会.  相似文献   

苏北湖区户用风光互补发电系统的设计与试验分析     

张东凤  王效华 《湖南农机》2009,36(5)

离网型风光互补发电系统是解决湖区电力供应短缺问题的新选择.以金湖县宝应湖为应用背景,对风光互补发电系统进行设计和试验分析,为该系统在此地区的推广提供技术依据.  相似文献   

企业内部控制的失效成因与强化措施     

李添瑜 《湖南农机》2009,(5):42-44

加强企业内部控制,是企业的最基础性工作,也是企业生存和发展的保证。然而,目前我国许多企业的内部控制还相当脆弱。内部控制已经成为管理企业的有效工具,其健全与否是企业生产成败的关键。依法完善切实可行的内部控制,建立健全的内部控制监督机构,改善内部控制环境,设立良好的控制程序,建立有效的会计控制系统是解决企业内部控制失效的有效措施。  相似文献   

基于PLC和触摸屏的塔机安全监控系统设计   总被引：1，自引：0，他引：1  

陈一帆 《湖南农机》2009,(6):23-26

塔式起重机是高层建筑施工必备的起吊运输设备。本塔机安全监控系统用PLC实现塔机电气控制,对从各传感器采集到的数据进行计算、判断处理,做出各种控制动作,用触摸屏以数值方式实时显示塔机运行过程中的主要状态参数,当测量值接近或超过设定值时,可自动预警或报警并记录当前各状态参数,并且能够切断相应控制电路,起到安全保护的作用。  相似文献   

厦门筼筜湖游泳生物资源状况     

戴泉水 《福建水产》2008,(3)

2007年11月和2008年5月,对筼筜湖的游泳生物开展了2个季度的调查.结果显示:调查出现的游泳生物种类有69种.其中鱼类44种,虾类7种,蟹类14种,头足类3种,口足类1种;渔获量的优势种为远海梭子蟹和尼罗罗非鱼,渔获尾数优势种则以硬头鲻和远海梭子蟹为主.湖内刺网平均单位面积渔获量1.0069g/m2·h,单位面积渔获尾数0.0192ind/m2·h.排水口年平均资源指数为1043.317g/网·h,资源密度为148.883ind/网·h.现存资源量为729.752kg,现存资源尾数为10.4168×104尾.调查结果表明,筼筜湖的游泳生物种类比2001年出现的60种和1992年的43种,分别增加15%和60.46%.表明筼筜湖的综合治理取得了明显的生态效果.  相似文献   

Potential for reintroduction of lake sturgeon in five northern Lake Michigan tributaries: a habitat suitability perspective     

Daniel J. Daugherty  Trent M. Sutton  Robert F. Elliott 《水产资源保护:海洋与淡水生态系统》2008,18(5):692-702

• 1. Conservation and rehabilitation efforts for lake sturgeon Acipenser fulvescens throughout the Great Lakes include the re‐establishment of self‐sustaining stocks in systems where they have been extirpated.
• 2. Information on the suitability of potential lake sturgeon habitat in tributaries is important for determining their capacity to support lake sturgeon stocking and to develop system‐specific rehabilitation strategies.
• 3. Geo‐referenced habitat information characterizing substrate composition, water depth, and stream gradient were applied to a life‐stage specific lake sturgeon habitat suitability index in a geographic information system to produce spatially explicit models of life‐stage specific habitat characteristics in five northern Lake Michigan tributaries from which lake sturgeon have been extirpated.
• 4. Habitat models indicated that high quality lake sturgeon spawning and staging habitat comprised 0 to 23% and 0 to 9% of the available habitat, respectively, whereas high quality juvenile lake sturgeon habitat was relatively ubiquitous throughout each river and comprised 39 to 99%.
• 5. Comparison of these data to lake sturgeon habitat availability in Lake Michigan tributaries currently supporting populations indicated that spawning and staging habitats may limit the ability of these systems to support spawning. Efforts to re‐establish lake sturgeon populations in these systems should consider the creation of spawning and staging habitat to increase reproductive and recruitment potential prior to the initiation of stocking efforts.

Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Effects of silvering state on induced maturation and spawning in wild female Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis>     

Akihiro Okamura  Yoshiaki Yamada  Noriyuki Horie  Tomoko Utoh  Naomi Mikawa  Satoru Tanaka  Katsumi Tsukamoto 《Fisheries Science》2008,74(3):642-648

ABSTRACT:   The effects of silvering state of wild female Japanese eels Anguilla japonica on the success of induced maturation and the following spawning were examined. Thirty-eight females, collected in Mikawa Bay, were divided into four stages based on their silvering state: yellow (Y1), late-yellow (Y2), silver (S1) and late silver eels (S2). Despite injections of salmon pituitary extract (SPE) through the standard technique, Y1 and Y2 eels did not respond to the treatment with undeveloped gonad (gonad-somatic index [GSI]: 0.3–0.9), and all these females died by 5 weeks, probably due to an abnormal physiological condition. Most S1 (81%) and S2 eels (100%) matured completely (GSI: 17.8–51.4), and finally spawned successfully (69% for S1, 89% for S2). S2 eels fully matured with oocytes of over 750 μm in diameter by significantly smaller number of injections of SPE (5–6 times) than the case of S1 eels (6–8 times). The amount of eggs released by S2 eels (0.65 ± 0.11 g/fish per body weight [BW]) was significantly larger than those by S1 eels (0.54 ± 0.09 g/fish per BW). There was no difference in fertilization and hatching rates between eggs released by S1 eels and those of S2 eels. These results indicate that the success of induced maturation and spawning in wild female Japanese eels depends on their silvering state, and matured eggs can be obtained efficiently through the use of S2 eels rather than other stages.  相似文献   

Reproductive biology of the commercial sea cucumber <Emphasis Type="Italic">Holothuria spinifera</Emphasis> (Echinodermata: Holothuroidea) from Tuticorin,Tamil Nadu,India     

P. S. Asha  P. Muthiah 《Aquaculture International》2008,16(3):231-242

The annual reproductive cycle of the commercial sea cucumber Holothuria spinifera was studied in Tuticorin, Tamil Nadu, India, from September 2000 to October 2001, by macroscopic and microscopic examination of gonad tubule, gonad index and histology of gametogenic stages, to determine the spawning pattern. The gonad consists of long tubules with uniform development. It does not confirm the progressive tubule recruitment model described for other holothurians. The maximum percentage of mature animals, gonad and fecundity indices, tubule length and diameter, with the observations on gonad histology, ascertained that H. spinifera had the peak gametogenic activity during September and October 2001 followed by a prolonged spawning period from November 2000–March 2001.  相似文献