日光温室采光性能的模拟分析

采光性能是温室中作物生长和发育的重要因素，是日光温室结构设计的基础，是提高温室经济效益、发展设施农业的关键。通过必要的假设与简化，建立了日光温室采光性能的数学模型，利用该模型模拟计算了温室采光量与其结构形状、几何尺寸、朝向、地理纬度、节气和时间之间的关系，找出了各因素对日光温室采光性能的影响，并分析研究了其变化规律，所得结论为正确地设计高产、高效、经济的日光温室奠定了基础。     

日光温室温度分析模型与模拟

分析了影响采光量的主要因素(脊高、采光面、地理纬度、温室方位、日照时间等),根据温室内热量交换的平衡,建立了日光温室内温度数学模型,利用Matlab软件对模型进行仿真求解,动态模拟出设计参数对温室内温度的影响,并对不同参数的温度与实测值进行比较,相对平均误差为5.56%。     

日光温室光控系统的设计

日光温室的光环境对于作物的生长和发育起着决定性的作用，日光温室光环境的自动控制是实现温室高产高效的重要内容。笔者研究、探讨了可用于温室采光和补光的控制系统。介绍了该系统的方案设计、元件选择和控制电路的设计，为实现日光温室光照自动控制奠定了基础。     

采光屋面透光材料的应用与研究综述

屋面采光是大空间建筑获取天然光照明的常用方式,采光屋面透光材料的性能对建筑外在形态和内部环境均有很大影响.综述了玻璃、聚碳酸酯板、乙烯-四氟乙烯(ETFE)膜三大类透光材料在采光屋面上的应用与研究现状,对比评价了不同材料的性能.介绍了四种典型材料:Sentryglas?Plus(SGP)夹层玻璃、气凝胶玻璃、光伏玻璃、光伏电池-乙烯四氟乙烯(PV-ETFE)气枕系统在采光屋面的应用与研究进展,指出安全、节能、太阳能利用是未来采光屋面透光材料的发展方向.     

新疆节能日光温室的原理及结构初探

本文通过研究新疆节能日光温室，即长后坡日光温室的太阳直射光在温室内的分布，给出确定节能日光温室建筑参数的采光和保温设计原则，按照此原则提出了节能日光温室优化设计的计算流程。     

大变形下直立锁边屋面系统的水密性研究

为了评价直立锁边屋面系统安装在柔性屋面结构上适应大变形能力和水密性,以苏州工业园区游泳馆金属屋面系统为例,取一个6.6 m×6.6 m试验单元设计了大变形下金属屋面系统的足尺水密性试验,建立屋面系统的整体有限元模型分析了屋面系统在结构大变形下的应力和变形,对保证屋面系统水密性的关键构造进行了精细化有限元分析.试验和分析验证了直立锁边屋面系统具备适应柔性屋面结构大变形的变形能力,计算直立锁边角变形只有2.18°,确保了良好的水密性.     

科技超市

项目合作XM9907001:轻型结构日光温室及电动卷盖系统轻型结构日光温室及电动卷盖系统是原国家科委"九·五"农业科技产业项目——工厂化农业的研究内容之一,是北京市农林科学院蔬菜研究中心研制成功的新型园艺设施。轻型结构日光温室采用新型轻体保湿材料替代传统的炉渣、黄土,使温室后坡重量减少60%,钢骨架材重量减少30%,温室造价降低10%。电动保温被及其卷盖不仅具有保温性好,减轻劳动强度,提高生产率的优点更重要的是可以延长温室采光时间、提高光效率。新型保温被不仅重量轻,而且具有良好的保温性、防水性、耐用性、机械卷盖系统运行可靠、造价低廉。与其它同效果的产品相比能源消耗仅是其中1/2。该项目技术已获国家专利,推出后深受广大农民的关注与青睐,市场前景广阔。     

北方常用三种温室结构光照优化设计

该文针对北方地区常用的单斜面、抛物面、圆拱型3种结构类型日光温室进行光照试验,测定其不同位点的光照和温度。经过试验对比分析,得到结果为:前屋面角度为40°的圆拱型温室内的光照环境相对较为均匀,对不同高度作物的生长适应性强,应优先选择圆拱型温室。     

日光温室的采光设计

本文给出了日光温室采光设计的详细计算方法，并提出了日光温室的采光设计指标：大于光补偿点４０００ｌｘ的６小时累计平均光照强度不低于２万ｌｘ，按照该指标要求，提出了日光温室采光设计的计算流程。     

竖向荷载下日光温室钢骨架承载力有限元分析

随着宁夏地区农村温室种植经济的发展,钢骨架日光温室的应用越来越广泛.通过调研,采集了宁夏地区日光温室钢骨架的典型结构形式及结构参数.利用有限元方法分析了一系列有限元模型在竖向荷载作用及不同结构参数条件下,日光温室钢骨架的承载力与变形特点的变化.提出不同形式的支座及其对钢构件的约束程度将使日光温室钢骨架承载能力产生较大的变化,支座刚度越大,承载能力越高.在3种杆件中,增加下弦杆直径的同时应使腹杆直径接近下弦杆直径是提高日光温室钢骨架承载能力的最佳措施.为宁夏地区日光温室钢骨架设计及制作提供参考.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has