塑料温室中湿帘风机通风条件下降温效果研究

为了能够充分了解湿帘风机降温系统在嘉兴地区高温高湿环境下的降温效果,以及温室中温度分布特征,在一个占地面积约3 072 m2,安装有湿帘风机降温系统的8连栋塑料温室中进行了相关因素的测试。试验结果表明:在环境相对湿度62%的情况下,使用湿帘风机降温时,温室内部平均温度降幅可达到4.8 ℃左右。证明湿帘风机系统在高温高湿的南方夏季也具有一定的降温能力。温室中水平方向上存在明显的温度梯度,风机一侧与湿帘一侧的温度差为2.5 ℃,沿水平方向的温度梯度为0.063 ℃m。温室中垂直方向上也存在明显的温度梯度,正午前后室外高温期间,温室中心部位垂直方向2个相差2 m位置点的温度差为2.6 ℃。      

三峡库区设施栽培降温效果比较研究

针对三峡库区夏季高温高湿的气候特点,通过比较湿帘-风机、风机-外遮荫、湿帘-外遮荫、自然通风-外遮荫、强制通风-侧窗降温系统的降温幅度的试验,指出在适合三峡库区的最佳降温方式为湿帘-风机的降温系统。试验表明:在天气晴朗,温室内空气湿度增大不多的条件下,采用湿帘-风机降温系统可使温室内气温比室外降低5～13℃,降幅可达10℃左右,并且温度的分布比较均匀。     

玻璃温室夏季组合降温措施试验研究

本文详细阐述了夏季温室内几种主要组合降温措施,即自然通风+外遮阳系统、机械通风+外遮阳系统、湿帘风机+外遮阳系统和湿帘风机+外遮阳+屋顶喷淋系统等降温措施,与此同时对温室内的温湿度环境变化规律进行分析.结果表明,四种降温措施分别使温室内、外温度差分别为-0.6℃、-1.2℃、-3.6℃和-7.4℃,由此可见湿帘风机+外遮阳+屋顶喷淋系统降温效果最佳;温室内、外湿度差分别为-10.5%、-6.5%、8%和6.8%.     

光伏温室室内外环境条件对比

为了测试光伏温室在实际生产过程中的降温效果及光伏板布局对光照的影响效果,对已建光伏温室进行了室内外温度、湿度和光照等数据测试。测试结果表明:在湿帘风机降温系统开启的条件下,对比室外环境条件,降温范围可达0.5～7.8 ℃,湿度差值范围为12.3%～33%;在光伏板布局采用间隔排列的情况下,透光率范围为32.64%～80.96%,平均透光率为66.27%。由此可见,光伏温室中湿帘风机降温系统具有良好的降温效果,光伏板布局的光照可以满足作物需要,是具有广泛应用前景的实用技术。      

湿帘系统循环运行降温初探

为了有效减小夏季玻璃温室的降温成本,本文针对减小湿帘风机循环运行降温的成本进行了探索性研究试验。试验结果表明：在夏季高温上午时段,利用Eldar控制系统控制湿帘风机的运行时间,当把温室内的温度设定在32～35℃时,在153min的时间段内,湿帘系统中水泵运行了43min,风机运行了68min;温室内温度与湿度成反比关系,温度越低,湿度越高; Eldar控制系统设定的温度差越大,湿帘风机开启的次数越少,运行的时间也越短。     

湿帘风机降温系统设计与参数选择方法

湿帘风机降温系统由特种纸质波纹蜂窝状湿帘、水循环系统、低压大流量节能风机以及相关控制装置组成。风机运行时,室外未饱和的空气在室内负压的作用下流经湿帘的多孔湿润表面,水分被蒸发,吸收过流空气中的大量潜热,从而降低过流空气自身的温度,源源不断地进入室内进行降温。湿帘风机降温系统一次性投资与运行费用低廉,因此在温室、畜禽舍及高温车间等地方得到广泛的应用,成为世界各国大面积农业生产建筑普遍采用的防暑降温设施之一。湿帘风机降温系统设计的合理与否,直接关系到其降温效果、使用寿命、运行经济与维护管理等。现以华南地区温…     

温室湿帘降温系统原理与应用

湿帘降温系统通过空气与水的直接接触,达到室内空气降温增湿的目的.系统具有降温效果明显、设备简单、安装方便、成本低和性价比高等优点,可广泛应用于温室、畜舍等和纺织车间等需要降温增湿的场所中.为此,根据湿帘表面水膜的传热传质特点建立了湿帘降温的理论模型,讨论了湿帘结构和运行参数对降温效果的影响,为温室湿帘降温系统的设计和运行提供了理论依据.     

半封闭温室关键系统设计与应用

半封闭温室是近年来新兴温室,其中温室气候走廊和正压送风系统是半封闭温室的关键系统设计。本文通过对半封闭温室内夏季温度分布的均匀性和风道风速测试试验,验证温室的降温能力和送风系统性能。试验结果表明,国产风机SFG5-4配套35米长风道,送风相对比较均匀,风速在4.3-4.7m/s之间;对于温度分布规律来说,在同一水平方向上,半封闭温室内各点的平均温差在1-1.8℃范围内,在同一高度方向温室内各点的平均温差在2.2-3.5℃范围内,且3.5米湿帘比2米湿帘降温效果好。     

连栋温室内湿帘-风机流场特性

为了解华南地区大型连栋玻璃温室在湿帘-风机通风条件下温度场与速度场的变化情况,探究该通风方式下,温室内的通风降温性能,以广州市农业技术推广总站示范基地的连栋玻璃温室为研究对象分别进行了稳态和瞬态计算,将稳态模型的计算结果与温室内监测点得到的数据进行对照,验证了计算模型的可靠性,并对湿帘-风机通风工况进行瞬态计算,得到温室内直观的温度和速度的分布情况及变化规律.结果表明:开启湿帘-风机系统后,湿帘侧最初风速可达1.6 m/s,通风过程中逐渐发展为从湿帘入口贯通风机出口的高速气流场,气流速度最终稳定在0.8 m/s;温室内温度场从湿帘侧到风机侧表现出梯度降温的变化特征,同时伴随着温室全局性的微小幅度降温;将风机流量增加1倍后,温室内气流的湍动程度增加,降温速度明显提高.得到的结果将为华南地区连栋玻璃温室的正常运行和精准调控温室内的小气候环境提供参考.     

湿帘风机降温系统安装高度对降温效果的影响

针对夏季温室内气温的垂直梯度大于10℃的问题,进行了湿帘风机安装高度对降温效果影响的对比试验。试验结果表明:对于冠层高度不超过2m的低矮作物,普通安装高度(湿帘高0.9m、风机高0.5m左右)时,中、下层温度分别在30℃和28℃左右,可以满足作物生长发育的温度要求;但对于番茄等植株高大的作物,其冠层常达到温室上层的高温区(34~35℃),适当提高安装位置(湿帘高2m、风机高1m左右),使得风机的流速场高于植株冠层顶部0.5m左右,使作物冠层的空气温度只有29~31℃,气温的垂直梯度只有4℃左右。     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

瓦房店市水果生产标准化发展研究

瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

对《种子法》存在问题的探讨

《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.     

和谐社会理论建设的几点哲学思考

在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。     

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.     

粉质仪和拉伸仪在面粉生产中的应用

在介绍粉质仪和拉伸仪结构和原理的基础上,探讨了粉质曲线中吸水率、形成时间、稳定时间、弱化度和评价值等指标与面粉品质的关系,以及如何根据拉伸曲线中面团最大拉伸阻力、延伸度和拉伸曲线面积等指标来评价面团品质,并结合生产实际,概述了粉质仪和拉伸仪在面粉生产中的作用。     

农村信息化服务的现状及建设措施

分析当前我国农村信息化服务的现状,提出加强农村信息化服务的新举措。     

车辆ABS控制算法的研究及探讨

对现代汽车的ABS控制算法作了一些简单的介绍,同时指出了它们的一些缺陷,相应地提出了几种对ABS的其它控制方法并加以探讨,其中着重论述了ABS门限值控制算法中参考车速的确定方法和基于附着系数的控制算法。