共查询到20条相似文献，搜索用时 78 毫秒
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我国现代温室环境控制硬件系统的应用现状及发展 总被引：3，自引：2，他引：1
现代化温室要想实现高效、均衡的连续生产产品,关键技术是设施的环境控制.为此,主要介绍了我国现代温室正在应用的单片机控制模式、基于PLC的控制模式、基于现场总线的分布式智能控制模式、基于ZigBee技术的无线网络智能控制系统模式等几种典型的环境控制硬件系统模式,并对其应用现状进行了综述,并提出了温室环境控制技术在今后可能的发展趋势-网络化的智能有线或无线控制. 相似文献
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现代温室环境智能控制的发展现状及展望 总被引：3，自引：0，他引：3
在简述智能控制技术基本理论的基础上,分析了现代温室环境智能控制系统的拓扑结构以及智能控制技术在现代温室环境控制中的研究和应用进展.现代温室环境智能控制涉及硬件结构和控制算法等问题.控制系统硬件配置多采用分布式系统框架,现场控制站功能可以采用单片机、可编程控制器或工业控制机来完成,系统网络结构有CAN总线、现场总线和工业以太网等多种形式.将多种控制算法交叉与融合的混合控制算法更能满足现代温室环境智能控制的要求.为此,探索了新型的温室内环境和生物信息的获取方法,开展了温室内小气候模拟和实验研究,为实现温室内作物生理指标的智能控制、智能控制系统硬件配置及结构优化提供了理论依据. 相似文献
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国内温室环境在线控制系统的研究进展 总被引：2，自引：0，他引：2
综述了温室在线控制系统的研究现状,按照温室在线控制系统的控制方法,将系统分为基于单片机控制、基于PLC控制、基于网络技术控制、基于工控技术控制(IPC)和基于总线技术控制等几类。目前,温室在线控制主要还是采用分段式控制和人工设定相结合的方法。未来温室在线环境控制的研究重点是控制系统的智能化和信号传输的无线化,通过综合考虑环境因子、作物生长及经济性等因素,来获得适合作物最佳生长条件的智能决策支持及控制系统。这将是未来温室在线控制系统的发展方向,能够达到改善作物品质和提高经济效益的目的。 相似文献
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按照单片机控制、网络控制、PLC控制和总线控制等方法对国内温室环境在线控制系统进行分类,对我国温室在线控制方式的研究及应用现状作了详细分析,为开展温室环境在线控制系统的应用研究提供参考。 相似文献
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分析研究了智能温室测控系统的架构方案，阐述了主从集散控制系统和基于现场总线的控制系统在现代温室中的应用，探讨了基于以太网的温室测控系统的架构方案，并指明了其应用前景。 相似文献
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《Journal of Agricultural Engineering Research》1998,69(3):249-254
A model to represent the discolouration of dried powder of carrots as a function of temperature was developed. Two types of carrots, Asian and European, containing large amount of lycopene and β-carotene, respectively, were tested. The dried powder was stored under an atmosphere with O2and at three different temperatures, 5,20 and 35°C. The surface colour of the powder was monitored during storage by a Hunter colour ratioa/b. In the proposed model, the rate of oxidation was assumed to be represented by the product of the fraction of concentration of oxidized pigment at arbitrary time and a specific rate of oxidation of pigment. The rate parameters in the proposed model were calculated by fitting the experimental data with smooth curves by trial and error at the end of the induction period but before discolouration took place. The frequency constant and activation energy, expressing the temperature dependence of the rate parameters, were expressed by the Arrhenius relation. The simulation results of a Hunter colour ratioa/bof dried powder at 25°C showed good agreement with the experimental data, suggesting that the proposed model was effective for the prediction of discolouration of dried powder of both types of carrot. The use of the induction period in the manner described may enable the shelf life of dried powder to be predicted. 相似文献
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感官检验棉花的品级,这是农村常见的一种检测手段.它的一个主要特点就是存在不确定性.这是由于检验员的品级检验水平存在一定的差异,其中有很多因素制约着检验的结果.文章对影响感官检验结果的因素进行了系统的分析. 相似文献
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从灾害经济学的角度探讨了城镇供水优化调度的必要性和可能性，认为在缺水不可避免的情况下，对供水进行优化调度可以减小缺水带来的损失，产生较好的减灾效益，特别是可以大大减小严重干旱的灾害效应。并根据水资源的特性，提出了缺水损失的计算模式以及优化调度的原则和方法。 相似文献
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The fractional outflow rate of water from the rumen, measured as the rate of disappearance of the chromium complex of ethylenediamine tetra-acetic acid, was related to a number of dietary factors. A multiple regression equation was derived which expressed fractional outflow rate as a function of the intakes of dry matter, ash, acid-detergent fibre and crude protein.The data analysed consisted of 243 observations for sheep on 59 diets, including forage, concentrate and mixed diets. The ranges covered by the data were: fractional outflow rate 0.7–3.6 day?1; dry matter intake 560–1400g/day; ash 4–30%, acid-detergent fibre 7–41%, crude protein 5–26 % of dry matter; there were no observations for sheep of less than 34 kg liveweight.The equation accounted for 56·3 % of the total variance. Between-sheep variance could not be calculated for the whole of the data but was undoubtedly substantial since, for a sixth of the data, it was known to account for 38 % of the total variance. 相似文献