控制电路分析

本文研究了电气控制电路图的图面区域的划分办法,接触器、继电器等自动电器触点位置索引的画法。介绍了一种阅读比较复杂的控制电路时既能避免遗漏、又不会重复的比较全面的分析方法。     

基于完成端口技术的大面积水域溶解氧含量监测系统设计

针对大面积水域溶解氧含量监测系统,设计了基于C/S模式的监测系统软件架构,应用完成端口通信技术,对监测系统的服务器进行网络通信优化,使其能够承载大量的数据监测客户端,提高实时数据传输的高效性和可靠性。     

基于RFID技术的监所巡更系统

介绍一种基于射频卡及读卡器进行软件开发而成的方便实用的监所巡更系统。由PC微机、射频卡及其读卡器等部分组成,完成巡更资料的采集、传输、管理等功能。该统既可以加强对监所的管理,又可以省去管理人员检查的麻烦,同时也适应各监所逐步普及计算机管理、提高管理水平的要求,具有很好的实用和推广意义。     

西南地区不同套种模式对土壤肥力及经济效益的影响

为探讨不同作物组合的种植模式对土壤肥力及经济效益的影响,寻找作物搭配合理、低投入高产出的套作模式。采用单因素随机区组试验,研究比较了4种套作模式(小麦/玉米/大豆、小麦/玉米/甘薯、小麦/高粱/大豆、马铃薯/玉米/大豆)的土壤肥力、产量及经济效益的差异。连续种植3年后,各种植模式的土壤养分含量基本维持或得到提升(速效钾除外)。甘薯茬口对全钾、速效钾消耗均较大,需适当提高钾肥用量。小麦/玉米/甘薯的总产量最高,小麦/玉米/大豆模式的大豆单产量最高,小麦的单产各模式无显著差异。不同模式收益表现为,小麦/玉米/大豆马铃薯/玉米/大豆小麦/玉米/甘薯小麦/高粱/大豆;产投比表现为,小麦/玉米/大豆马铃薯/玉米/大豆小麦/玉米/甘薯小麦/高粱/大豆。小麦/玉米/大豆收益为14196.41元/hm~2,产投比为3.69:1,均为所有模式中最高,加之大豆茬口可以活化土壤养分,是相对理想的套作模式。     

TIBA对不同耐荫性大豆套作苗期生长和倒伏率的影响

三碘苯甲酸(TIBA)是一种生长素运输抑制剂,具有抑制顶端生长的作用。为分析套作模式中,喷施TIBA对不同耐荫性大豆品种幼苗期生长和倒伏的调控效应,本研究设置50,100,150,200和250 mg·kg^-1的TIBA浓度处理,以清水和无遮荫为对照处理,调查大豆形态、干物质和倒伏性状。结果表明:与无荫蔽对照相比,荫蔽下大豆株高增加,茎粗、节数、分枝数、SPAD、干物质则显著降低,倒伏率显著增加。喷施TIBA后,大豆株高显著降低,茎粗、节数无改变,分枝数增加,叶面积下降,叶片SPAD无变化,干物质下降,大豆倒伏率显著降低。套作模式下大豆幼苗期TIBA喷施的适宜浓度为50~100 mg·kg^-1,且适宜浓度与品种自身耐荫能力有关,强耐荫品种南豆12适宜浓度为50 mg·kg^-1,而荫蔽敏感型大豆XBM为100 mg·kg^-1。浓度高于150 mg·kg^-1处理虽然更有利于降低株高、减少倒伏,但大豆干物质积累量偏低,不利于培育壮苗。     

Response of Mucuna pruriens to symbiotic nitrogen fixation by rhizobia following inoculation in farmers' fields in the derived savanna of Benin

 Leguminous cover crops such as Mucuna pruriens (mucuna) have the potential to contribute to soil N and increase the yields of subsequent or associated cereal crops through symbiotic N fixation. It has often been assumed that mucuna will freely nodulate, fix N₂ and therefore contribute to soil N. However, results of recent work have indicated mucuna's failure to nodulate in some farmers' fields in the derived savanna in Benin. One of the management practices that can help to improve mucuna establishment and growth is the use of rhizobial inocula to ensure compatibility between the symbiotic partners. Experiments were conducted in 1995 and 1996 on 15 farmers' fields located in three different villages (Eglimé, Zouzouvou and Tchi) in the derived savanna in Benin. The aim was to determine the response of mucuna to inoculation and examine the factors affecting it when grown in relay cropping with maize. The actual amount of N₂ fixed by mucuna in the farmers' fields at 20 weeks after planting (WAP) averaged 60 kg N ha^–1 (range: 41–76 kg N ha^–1) representing 55% (range: 49–58%) of the plant total N. The result suggested that mucuna in these farmers' fields could not meet its total N demand for growth and seed production only by N₂ fixation. It was estimated that after grain removal mucuna led to a net N contribution ranging from –37 to 30 kg N ha^–1. Shoot dry weight at 20 WAP varied between 1.5 and 8.7 t ha^–1 and N accumulation ranged from 22 to 193 kg N ha^–1. Inoculation increased shoot dry matter by an average of 28% above the uninoculated treatments, but the increase depended on the field, location and year. For the combinations of inoculated treatments and farmers' fields, the response frequency was higher in Eglimé and Tchi than in Zouzouvou. The response to inoculated treatments was dependent on the field and inversely related to the numbers of rhizobia in the soil. Soil rhizobial populations ranged from 0 to >188 cells g^–1 soil, and response to inoculation often occurred when numbers of indigenous rhizobia were <5 cells g^–1 soil. In two farmers' fields at Zouzouvou where extractable P was below 10 μg g^–1 soil, mucuna did not respond to rhizobial inoculation despite a higher population of rhizobia. Significant relationships between mycorrhizal colonization, growth and nodulation of mucuna were observed, and inoculated plants with rhizobia had a higher rate of colonization by arbuscular mycorrhizal fungi (%AMF) than uninoculated ones. Therefore, it was shown that mucuna will establish and fix N₂ effectively in those fields where farmer's management practices such as good crop rotation and rhizobial inoculation allow a build up of AMF spores that might lead to a high degree of AMF infection and alleviate P deficiency. Received: 14 June 1999     

洞庭湖区农业经济发展和环境的历史演变

本文对人口和劳力、城镇、交通运输几个与洞庭湖农业经济影响较大的因素进行了历史分析,认为：①湖区历史人口和劳动力的变迁。受外来人口机械变动影响较大,大体外来人口移人多,人口就发展;反之,则下降。人口数量几度起落,变化较大。进而影响农业发展的进程。②湖区的村落和城镇发展较早,其变迁与湖区的农业经济发展有着密切的联系,一部分居民点由予农业经济条件特别优越,逐渐发展成为小城镇,有的因为水运便利,成为附近农副产品的集散地,进而发展成为较大的城市。③交通运输业的发展与农业生产的盛衰、人口和劳动力的多寡、城镇发展的快慢有着密切的关系。     

现代通信技术在设施农业中的应用综述

设施农业的发展离不开现代通信技术的支持。现代通信技术正日益成为决定设施农业效益的关键。按照传输媒质分类,现代通信技术可以分为有线通信技术和无线通信技术。对目前设施农业领域常用的现代通信技术进行了评述,并对各种通信技术在设施农业中的应用优势、局限性和适用范围进行了分析比较。在此基础上,提出了几种适用于设施农业的现代通信系统解决方案,旨在为设计设施农业环境智能测控系统提供参考。     

电力光载无线通信技术在电力接入网中的应用

分析了电力接入网技术中光纤接入、电力线载波通信、无线公网接入、230电台接入等技术的优缺点,提出了建立高速、双向、实时、集成的电力通信网络是实现智能电网基础的观点,并最大限度地利用电力光载无线通信技术,设计了电力光载无线通信技术模式原理图,构建了输变电在线监测无线通信系统网络架构以及配用电无线通信系统网络架构。