共查询到20条相似文献,搜索用时 78 毫秒
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目前,发达国家的现代化大型温室采用透明材料覆盖,配有供暖、通风、灌溉和增施二氧化碳等比较完备的设施,作物可以全年生产。为此,介绍了世界现代化温室的类型及代表温室。从温室形状、温室方位、北墙绝缘、保温幕、双层覆盖物5个方阐述了国外现代化大型温室保温性能的改进现状,可对我国现代化温室的改进起到借鉴作用。 相似文献
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本文采用模糊分析法对我国节能温室中大量使用的保温薄膜进行了使用性能的评估,通过建立一套以保温性、经济性、力学性、环保性等主要评价指标的综合评价体系,从而为我国从事设施农业生产的众多农户在购买保温薄膜时提供一套行之有效的选择方案。 相似文献
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新疆新型高效节能日光温室标准化设计探讨 总被引:4,自引:0,他引:4
日光温室标准化设计的目的是为了提高新疆南北疆日光温室的综合性能,根据新疆的自然条件和气候特征,对两地区的日光温室建造参数进行标准化设计,通过对这两种结构日光温室的测试结果,分析在新疆独特气候下温室参数对日光温室性能的影响。温室保温性能验证实验表明:标准化设计的温室在南北疆喀什塔城两地分别在外界-10.7℃、-8.1℃低温环境下,其温室内冬至日的平均温度可达到19.9℃、22.8℃,最低温度为15.3℃、18.8℃,最高气温达到33℃、30.1℃,标准化设计温室保温效果好,并从实际生产角度充分验证了节能日光温室的使用性能。 相似文献
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日光温室冬季保温性能的好坏是制约菜农经济收入的重要因素之一,提高温室的保温性能、降低能耗是提高温室生产效益的最直接手段。该文以北京市延庆县为例,对当地土墙温室、土墙包砖温室和砖墙温室3种类型日光温室的温度进行了监测,对保温性能进行了对比分析,提出了日光温室增温保温效果的技术改进措施。 相似文献
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保温被具有防水、保温、隔热等诸多优点,所以在我国大棚种植中广泛使用,大棚保温的首选就是保温被,保温被的保温效果好、使用寿命长。在本文中我们针对温室大棚中使用保温被技术要求进行分析研究。 相似文献
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不同方式封装的相变材料蓄热效果研究——基于日光温室 总被引:3,自引:0,他引:3
相变材料应用于日光温室中可以将温室白天多余的热量转移至夜间,起到调节温度的作用。为此,测试了经过两种不同方式封装后的相变材料在日光温室中的实际应用效果。通过与普通砖墙温室对照分析发现:两种类型相变材料温室均具有一定蓄热保温性能。内渗型相变材料温室比普通日光温室室温晴天夜间平均高0.9℃,阴天夜间平均高0.3℃;外挂型相变材料温室晴天比普通砖墙温室夜间温度平均高0.7℃。通过对两种类型相变材料温室综合应用效果比较发现,内渗型优于外挂型。此结果为相变材料在温室中的应用提供参考。 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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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
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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