夏季机械通风式笼养鸡舍内外颗粒物特征与影响因素分析

以机械通风式笼养蛋鸡舍夏季舍内及舍外颗粒物为研究对象,采用风机将鸡舍内颗粒物排放到舍外,监测舍内、外颗粒物浓度变化,并分析颗粒物的传播规律。结果表明:笼养蛋鸡舍内、外以对人体危害最大的细颗粒物为主,且鸡舍外颗粒物主要来源于舍内,其浓度最高可达到舍内的55.2%;舍外颗粒物粒径越小,在空气中传播的距离越远,越容易对周围居民的健康造成影响。通过分析鸡舍内、外颗粒物浓度日变化,发现舍内工作人员活动和喂料机工作均会扰动舍内沉积的颗粒物,并惊动蛋鸡,致使蛋鸡活动性增强,引起舍内、外颗粒物浓度升高。同时,随着蛋鸡日龄的增加或空气湿度的下降,舍内、外颗粒物浓度均呈现升高的趋势。因此,控制鸡舍内颗粒物浓度并采用适当的降尘措施将有利于保障蛋鸡和工作人员的健康、减轻畜禽场颗粒物对周围环境的危害。     

机械通风式笼养鸡舍内外颗粒物特征与影响因素分析

以夏季机械通风式笼养蛋鸡舍内外颗粒物为研究对象,采用风机将鸡舍内颗粒物排放到舍外,监测舍内、外颗粒物浓度变化,并分析颗粒物的传播规律。结果表明:笼养蛋鸡舍内、外以对人体危害最大的细颗粒物为主,且鸡舍外颗粒物主要来源于舍内,其浓度最高可达到舍内的55.2%;鸡舍外颗粒物粒径越小,在空气中传播的距离越远,越容易对周围居民的健康造成影响。通过分析鸡舍内、外颗粒物浓度日变化发现,舍内工作人员活动和喂料机工作均会扰动舍内沉积的颗粒物,并惊动蛋鸡,致使蛋鸡活动性增强,引起舍内、外颗粒物浓度升高。同时,随着蛋鸡日龄的增加或空气湿度的下降,舍内、外颗粒物浓度均呈现升高的趋势。因此,控制鸡舍内颗粒物浓度并采用适当的降尘措施将有利于保障蛋鸡和工作人员的健康,减轻畜禽场颗粒物对周围环境的危害。     

夏季机械通风式笼养鸡舍内外颗粒物特征与影响因素分析

以机械通风式笼养蛋鸡舍夏季舍内及舍外颗粒物为研究对象,采用风机将鸡舍内颗粒物排放到舍外,监测舍内、外颗粒物浓度变化,并分析颗粒物的传播规律。结果表明:笼养蛋鸡舍内、外以对人体危害最大的细颗粒物为主,且鸡舍外颗粒物主要来源于舍内,其浓度最高可达到舍内的55.2%;舍外颗粒物粒径越小,在空气中传播的距离越远,越容易对周围居民的健康造成影响。通过分析鸡舍内、外颗粒物浓度日变化,发现舍内工作人员活动和喂料机工作均会扰动舍内沉积的颗粒物,并惊动蛋鸡,致使蛋鸡活动性增强,引起舍内、外颗粒物浓度升高。同时,随着蛋鸡日龄的增加或空气湿度的下降,舍内、外颗粒物浓度均呈现升高的趋势。因此,控制鸡舍内颗粒物浓度并采用适当的降尘措施将有利于保障蛋鸡和工作人员的健康、减轻畜禽场颗粒物对周围环境的危害。     

夏季机械通风式笼养鸡舍内外颗粒物特征与影响因素分析

以机械通风式笼养蛋鸡舍夏季舍内及舍外颗粒物为研究对象,采用风机将鸡舍内颗粒物排放到舍外,监测舍内、外颗粒物浓度变化,并分析颗粒物的传播规律。结果表明:笼养蛋鸡舍内、外以对人体危害最大的细颗粒物为主,且鸡舍外颗粒物主要来源于舍内,其浓度最高可达到舍内的55.2%;舍外颗粒物粒径越小,在空气中传播的距离越远,越容易对周围居民的健康造成影响。通过分析鸡舍内、外颗粒物浓度日变化,发现舍内工作人员活动和喂料机工作均会扰动舍内沉积的颗粒物,并惊动蛋鸡,致使蛋鸡活动性增强,引起舍内、外颗粒物浓度升高。同时,随着蛋鸡日龄的增加或空气湿度的下降,舍内、外颗粒物浓度均呈现升高的趋势。因此,控制鸡舍内颗粒物浓度并采用适当的降尘措施将有利于保障蛋鸡和工作人员的健康、减轻畜禽场颗粒物对周围环境的危害。     

保育舍冬季湿热环境与颗粒物CFD模拟研究

为对保育舍内环境质量状况进行评估和改善舍内环境提供有益参考,应用CFD对采用负压通风和水泡粪保育猪舍的气流场、温度场、湿度场和颗粒物浓度场进行三维稳态模拟。由模拟结果可知:在冬季送入气流,舍内动物所在区域高度为0.2 m的风速基本保持在0~0.2 m/s,大部分区域风速在0.1 m/s以下,相对湿度则基本在60%~70%之间,舍内的平均温度保持在26~34℃,大部分区域的PM_(2.5)、PM_(10)和TSP质量浓度分别在0~0.1 mg/m~3、0~0.7 mg/m~3和0~1.0 mg/m~3之间。由《规模猪场环境参数及环境管理》可知,舍内环境质量基本满足保育猪对冬季环境需求,但在单元入口及墙角处仍有优化空间。     

基于CFD畜禽车厢体内温度场和速度场的模拟

为避免畜禽运输车在运输过程中因气流不均导致家禽损失,利用CFD模拟方法对畜禽运输车封闭式厢体内的温度场和速度场进行仿真分析。模拟结果表明,温度、风速较大的区域主要集中在每一层的第3、第4栏中,速度分布模拟值与实测值的相对误差范围为2.7%~5.1%,温度分布模拟值与实测值相对误差为1.2%~4.1%。模拟的气流速度和温度与实测的气流速度和温度值有着相同的变化规律,其中实测值与模拟值的最大误差不超过2℃,但由于气流的不均匀,高温仍集中在每一层的尾部。使用CFD模拟方法能够真实表达畜禽运输车厢体内气流状态,对厢体内温度场和气流场的模拟是一种有效的方法。     

单栋塑料温室内多因子综合CFD稳态模拟分析

为分析单栋塑料温室内的综合环境:气流场、温度场、湿度场、CO2浓度场,建立了包括温室内外空间、室内作物和土壤层等的温室环境几何模型。将温室内的湿空气看作水蒸气、CO2和干空气的混合气体,在分析温室中太阳辐射、作物与环境的质热交换,动量及质能传递过程的基础上,对单栋塑料温室内的环境因子进行了稳态模拟。温室内热辐射传递过程采用蒙特卡罗法模拟方法;将室内作物简化为连续固体换热模型,采用剪应力输运模型(SST)表述温室内的空气紊流。结果显示:温室通风对温度、湿度和CO2分布的影响很大,温室内部上风向温度低,湿度小,同时CO2浓度也不高;温室下风向作物冠层的环境未达到优化状态;模型的预测值低于实测值,但变化规律相似,温度、湿度、CO2含量的预测相对误差分别低于8%、6%和7%。     

不同耕作模式下农机作业对PM2.5、PM10和TSP排放的影响

农业机械可以提高农田作业效率、提高农业生产率,但也会加剧农田扬尘的排放,造成环境污染。本研究以北京市昌平区玉米收获与小麦耕种环节农机作业为研究对象,揭示了农机作业对农田PM2.5、PM10和TSP三种颗粒物排放的影响。结果表明：（1）在小麦耕种阶段,农机作业对农田扬尘浓度的影响程度由大到小依次为秸秆切碎、旋耕、免耕播种和传统播种;（2）传统耕作模式排放的颗粒物总量为保护性耕作模式的4.6~6.7倍,保护性耕作模式减少了耕作环节,减少了农机下地次数,从根本上减少了农田扬尘;（3）农机作业会对农田区域大气造成污染,影响空气质量。     

夏季奶牛场生物气溶胶分布规律与环境影响因子研究

为探究典型季节下的奶牛场生物气溶胶的分布规律和多元环境因子对其影响程度,对天津市某规模化奶牛场生物气溶胶、环境参数进行连续采集,分析了夏季奶牛场生物气溶胶浓度和载体粒径的时空分布规律,同时筛选出对其浓度具有重要影响的环境因子。结果表明,在空间分布上,牛场近地面1 m高度处的生物气溶胶浓度显著高于近地面4 m高度处浓度(P<0.01)。在粒径分布上,各采样点的分布规律无显著差异(P>0.05),不同粒径粒子所占比例接近且存在粒径越小所占比例越小的趋势,粒径大于2.1μm的粒子约占总数的80%。运用随机森林模型得到了10个影响因子对生物气溶胶浓度的影响程度,其中风向(WD)、温度(T)、紫外辐射强度(UV)、悬浮颗粒物浓度(PM100)等对浓度影响较大。为进一步探究影响因子之间的关系,通过层聚类的方法分析各影响因素之间的共线性关系,发现PM10、PM1与PM2.5之间以及UV与GHI之间具有强共线性关系,可以去除强共线性影响因子,保留组内一种环境因子为代表,以节约采集成本。本研究可为国内牛场空气环境污染排放测定提供参考。     

基于CFD的多风道风送喷雾流场数值分析与试验研究

为研究果园喷雾机的气流和雾滴沉积分布情况,通过数值分析与试验相结合的方法,研究了一种适用于果园植保的多风道风送喷雾系统气流场和气液两相流场分布规律。研究结果显示,该多风道风送喷雾系统的外部气流场分布较为均匀,喷射出风口出口处的气流速度试验值与仿真值相对误差＜13.7%,随着测量距离增大,气流速度逐渐衰减,其绝对误差基本在0~2 m/s。雾滴场在-0.6~0.6 m喷雾区域内雾滴沉积量（百分比）的仿真值和试验值相对误差＜14%,数值分析结果较为准确地反映风送喷雾系统的气流分布和雾滴沉积特征。      

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。