频率、温度和大豆蛋白对牛乳介电特性的影响

为了给牛乳中植物蛋白含量的检测提供一种方法,以生鲜牛乳为对象,采用矢量网络分析仪和同轴探头研究了频率(20~4 500 MHz)、温度(5~75℃)和大豆蛋白质量分数(0~3.98%)对生鲜牛乳介电特性(相对介电常数ε'和介质损耗因数ε″)的影响规律;建立了27 MHz下介电参数与温度和大豆蛋白质量分数的关系模型,并对模型进行了验证。结果表明,ε'随频率和温度的增大而减小;ε″在1 000~4 000 MHz间有最小值,且当频率小于1 000 MHz时,ε″随温度的增大而增大,但大于4 000 MHz时ε″随温度的增大而减小;ε'和ε″均随大豆蛋白质量分数的增加而线性增大;可用二元二次多项式表达牛乳的ε'和ε″与温度和大豆蛋白质量分数的关系,27 MHz下所建模型的决定系数分别为0.992和0.998。     

塿土介电特性与水分检测频率及温度影响

为了确定基于介电特性的土壤含水率传感器的合适检测频率,并降低温度对介电参数的影响,以陕西关中地区的塿土为对象,利用矢量网络分析仪和同轴探头技术研究了信号频率(10～4 500 MHz)、土壤含水率(9%～25%)和温度(5～50℃)对土壤相对介电常数ε’和介质损耗因数ε″的影响,分析了介电参数变化的原因及频率、含水率和温度对电磁波穿透深度的影响规律.研究结果表明,在10～4 500 MHz频段内,随着频率的增大,土壤的ε’单调递减,而ε″先增大,后减小,进而再增大;ε’和ε″均随含水率和温度的增大而增大;穿透深度随频率、含水率和温度的增大而减小;频率、含水率和温度是影响土壤介电参数及穿透深度的主要因素.50～100MHz是基于介电特性检测土壤含水率的最佳频段.     

微波频率、含水率与无机盐对小麦胚芽介电特性的影响

为探明微波稳定麦胚的机制,以小麦胚芽为研究对象,研究了不同测量频率、含水率、脂肪含量及添加不同无机盐条件下麦胚粉体的介电特性(介电常数ε'和介电损耗因数ε″)。实验结果表明,在2个常用微波频率下,小麦胚芽ε'在频率为915 MHz时略大于2 450 MHz时,但ε″在2 450 MHz时明显大于915 MHz时;小麦胚芽介电特性随含水率的增加而增大,当其含水率从4%增至16%时,其ε'和ε″分别从2.61和0.02升高至4.32和0.8;不同脂肪含量的小麦胚芽的介电特性相差较小,尤其是ε″;对比添加5种无机盐后小麦胚芽介电特性发现,Na Cl对其ε'和ε″有明显增加作用,尤其是当Na Cl的质量分数为1%时,效果最明显。     

不同类型蛋白质及其添加量对牛乳介电特性的影响

为了了解不同类型蛋白质及其添加量对生鲜牛乳介电特性的影响规律,为牛乳蛋白质掺假提供新的检测手段,采用同轴探头技术测量了20~4 500 MHz范围内乳清蛋白、大豆蛋白和三聚氰胺的蛋白质添加量(0~4.70%)对生鲜牛乳相对介电常数ε'和介质损耗因数ε″的影响规律,分析了不同类型蛋白质及其添加量对介电特性的影响机理。结果表明:在所测频率范围内,牛乳的ε'随频率的增加而减小,牛乳的ε″在2 000 MHz附近有最小值;当蛋白质添加量相同时,添加大豆蛋白的牛乳具有最大的ε',而添加三聚氰胺的牛乳具有最小的ε';添加乳清和大豆蛋白的牛乳的ε'和ε″均随蛋白质添加量的增加呈线性增大,但添加三聚氰胺的牛乳的ε'和ε″与蛋白质添加量之间的相关性不明显。研究说明,不同类型的蛋白质及其添加量对牛乳介电特性的影响规律不同,这种差异使基于介电特性识别牛乳中不同类型的蛋白质及其添加量成为可能。     

枸杞果实介电特性与贮藏时间相关性研究

研究了不同枸杞品种果实介电参数与测定频率、贮藏时间的相关性,并就此相关性进行了探讨,为下一步研究枸杞果实介电参数与内部品质间的相关性打下良好理论基础。研究结果表明:枸杞果实介电参数值会随测试频率的增加而呈规律性变化,阻抗Z、电感L、电阻R值随测试频率的增加而减小;在全频率段,各处理组介电参数值无明显差异性,其显著差异性主要表现在低频阶段。3.98MHz频率下,阻抗Z、电阻R、介质损耗因子ε″与贮藏时间线性正相关,电容C、介电常数ε'与贮藏时间线性负相关。各枸杞品种的电容C、介电常数ε'、介质损耗因子ε″随贮藏时间的变化值均存在显著差异性。     

高温处理对食用调和油微波介电特性与品质的影响

以食用调和油为研究对象,采用同轴探头技术测量了高温处理（120～240℃,3～15h）后调和油在200～4500MHz的微波介电特性和品质指标。结果表明：未处理调和油的相对介电常数ε′r和介质损耗因数ε″r随频率的变化而变化,经高温处理后ε′r和ε″r基本不随频率改变。与未受高温处理相比,处理使同频率下调和油的ε′r减小,ε″r增大。高温处理的温度、时间对介电参数值有一定的影响。当温度大于180℃时,随着处理时间的增加,调和油的酸价迅速增大;当温度为120℃时,处理时间对过氧化值有明显的影响。     

微波频率和温度对食用植物油介电特性的影

采用同轴探头技术研究了20～90℃、200～4 500 MHz内菜籽油、大豆油、花生油、玉米油、调和油的介电特性,分析了介电参数值随频率和温度变化的原因.结果表明:同频率下,菜籽油具有最大的相对介电常数和最小的介质损耗因数,而玉米油则相反.在500～4 000MHz间,介电参数与食用油中的饱和与不饱和脂肪酸含量间具有较好的线性相关性.相对介电常数随温度升高线性减小,但介质损耗因数则线性增大.菜籽油的介电参数受温度影响变化最明显,而玉米油最不明显.随着频率或温度的增加,电磁能在食用油中的穿透深度减小.     

基于介电特性的薏米含水率检测方法

研究了测量信号频率(1～1 000 kHz)、温度(5～40℃)和含水率(14.7%～22.7%)对薏米相对介电常数的影响,分析了影响相对介电常数变化的原因,建立了100 kHz下基于相对介电常数和样品温度预测薏米含水率的数学模型,并对模型进行了验证。研究结果表明,在1～1 000 kHz频段内,薏米的相对介电常数随着样品含水率和温度的升高而增大,却随着信号频率的增大单调减小;频率一定时,可用三次多项式表示含水率与相对介电常数和温度的关系;100 kHz下模型的决定系数是0.997 6,实测薏米含水率与预测含水率的决定系数为0.997 7。     

基于介电特性与回归算法的玉米叶片含水率无损检测

利用0.06~200 k Hz范围内拥有36个频率点的LCR测量仪及自制夹持平行电极板,测量280片不同含水率玉米叶片的相对介电常数ε'及介电损耗因子ε″;利用干燥法测量玉米叶片的湿基含水率。利用逐步回归法(SWR)与多元线性回归(MLR)结合的线性建模方法和连续投影算法(SPA)与支持向量回归(SVR)结合的非线性建模方法,分别建立玉米叶片介电参数(ε'、ε″及两者融合信息3种参数)与湿基含水率的关系模型,并应用留一交叉验证法选取2种建模方法的最佳关系模型。分析表明,非线性模型较线性模型具有更高的预测能力,且基于ε'与ε″的融合信息运用连续投影算法(SPA)与支持向量回归(SVR)相结合的非线性建模方法使模型原72个变量精简到10个,剔除了模型中冗余度较高的变量,有效降低了模型的复杂度,得到最高的测试集决定系数R2P(0.804)和最小的测试集均方根误差RMSEP(0.017 6)。结果表明基于介电特性的玉米叶片含水率无损检测方法是可行的,为快速检测其他农作物的生理信息提供了一种可靠的方法。     

数显式豆浆总固形物含量检测仪设计与试验

为了给豆浆总固形物含量的检测提供一种简单、便捷的仪器,首先研究了豆浆的总固形物含量(2.13~6.50 g/(100 m L))和温度(20~70℃)对其电导率的影响规律。结果说明,豆浆的电导率随总固形物含量和温度的增大而增大,可用二元二次模型表达豆浆的电导率与总固形物含量、温度的关系,该模型的决定系数为0.994。进而设计了以STC12C5A16S2单片机为控制器、以DJS-1型电导电极为电导率传感器、以DS18B20为温度传感器、以锂电池供电的便携式豆浆总固形物含量检测仪硬件系统。用C51语言设计了检测仪的软件,实现了数据的采集、处理和显示。对该检测仪的检验结果说明,当总固形物质量浓度在2.00~8.00 g/(100 m L)范围内时,该检测仪的总固形物含量测量误差为-0.52~0.37 g/(100 m L),平均绝对误差为0.17 g/(100 m L),响应时间小于5 s。     

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。