梨的各向机械特性差异

硬度是水果质量评价的一个十分重要的指标。与水果硬度有关的机械特性有破坏应力、破坏应变、破坏能和杨氏模量等。以前,人们常假设水果内各处机械特性基本一致,有关水果的非均质、各向异性机械特性的研究很少。本文研究了梨肉取样部位、方向、深度及朝向对破坏应力、破坏应变、破坏能和杨氏模量等指标的影响。试验表明：样品的部位、方向、深度等显著影响４个机械特性指标,而朝向对指标的影响呈极不显著。     

河套苹果梨机械特性的试验研究

以完整苹果梨果实为试样,对其进行压缩试验,得到力-变形曲线.结果表明:不同的加载速率和压头形式影响生物屈服力、破裂力和变形量的大小;不同硬度的苹果梨在垂直压缩时的力学特性明显不同;苹果梨的刚度值与变形存在相关性.该试验可为苹果梨的生产、运输、加工、分级以及机械设计等提供必要的方法与力学参数.     

可见近红外光谱检测河套蜜瓜糖度和硬度研究——基于LS-SVM

最小二乘支持向量机是水果品质可见近红外光谱检测中新近发展起来的建模方法。为此,详细介绍了最小二乘支持向量机的工作原理以及基于Matlab环境的LS-SVM工具箱的使用;在此基础上,运用主成分分析和LS-SVM法建立了基于可见近红外光谱的河套蜜瓜糖度和硬度检测模型,并分析了样品糖度、硬度的真实值和预测值的相关性。预测结果表明:糖度和硬度预测值与真实值决定系数R2分别为0.865和0.852。LS-SVM法建模速度快、准确率高、易于实现,在可见近红外光谱数据分析中有很大的实用价值。     

圣女果常温贮藏过程中压缩特性试验

运用万能试验机对常温贮藏下的圣女果进行压缩特性试验,研究了不同压头、不同压缩速度下的压缩曲线,同时对破坏极限Frax屈服极限Fs、刚度K、变形能Us、破坏能Ub等压缩特性指标的变化规律进行了分析.结果表明:不同压头和不同加载速度对屈服极限Fs、破坏极限Fmax与变形量的大小都有影响;刚度K和屈服极限Fs随贮藏时间的延长逐渐下降,变形能Us逐渐上升,而破裂极限Fmax和破坏能Ub的变化比较复杂.研究结果对圣女果贮藏、运输等都具有实际意义.     

番茄力学特性的研究

通过对番茄的压缩试验，测得其力一位移曲线，得出在相同加载速率下，不同硬度的番茄在横、纵向压缩时的力学特性及刚度与变形之间的关系式。同时，对番茄皮进行了横、纵向的拉伸试验，得到了番茄皮的弹性模量与应变之间的关系表达式，确定了可以用整体番茄的破裂强度与破裂延伸率和番茄皮的破坏强度值作为番茄破坏的评价指标，为建立番茄力学模型及机械设计提供了力学参数。     

苦荞浸蒸处理前后的力学特性

由于苦荞具有皮韧仁脆的特点,在脱壳过程中破碎率高、脱壳困难。为此,对浸蒸前、后的苦荞进行力—变形实验,通过实验测得其力—变形曲线;根据曲线数据,得出其硬度、破坏力、破坏能等常规力学参数;通过对比得出浸蒸处理后的苦荞破坏力和破坏能略有降低,苦荞仁的破坏力和破坏能显著增加,表明表皮结合强度降低,有利于减小脱壳破碎率。同时,对苦荞碎片和籽粒受压时横断面变化情况进行观察,得出苦荞籽粒的断裂位置主要位于胚两侧、籽粒沟槽处和受压接触点。     

荔枝物理参数和机械特性的试验研究

为了给荔枝精深加工机械的研发提供设计依据和理论基础,对荔枝的物性参数(球度、果壳厚度和鲜果平均密度等)和机械特性(压缩破坏载荷及变形)进行了测定.结果表明:机械加工中荔枝鲜果可以作为球体处理;不同部位果壳的厚度差异较大;各品种的密度都略大于1×103 kg/m3;压缩破坏平均载荷约60N;破坏时的平均变形量约10mm.     

荔枝果核力学特性分析及试验

针对荔枝果核的物理机械特性,运用Hertz弹性接触理论,建立果核压缩过程力学模型.通过对荔枝果核的压缩试验,测得其理学特性参数,结果表明:荔枝果核在压缩过程中主要为弹性变形,达到破坏极限时,果核产生应力裂纹或破碎而破坏;果核的弹性模量在20～50MPa之间,最大值出现在压缩开始阶段,并逐渐减小,趋于稳定.上述结果为荔枝去核理论的发展及相关机械的设计等提供了必要的参考.     

加载速度对稻米籽粒剪切特性影响的研究

稻米籽粒的剪切特性指标可以用来评价稻米的品质.为此,通过剪切试验获得了稻米籽粒剪切特性的力学指标(硬度、破坏能、破坏力及破坏应力等),并研究了不同加载速度下稻米的剪切特性指标,通过多项式回归建立了剪切特性指标与加载速度之间关系的回归方程,为评定和控制水稻的最后质量提供新的手段和研究方法.     

龙眼力学参数测试与分析

对龙眼果实、果核进行压缩试验表明:龙眼整果的压缩力-变形曲线为二次多项式关系,其横向和纵向的刚度相近,弹性模量为0.90～0.95 MPa;果核的压缩力-变形曲线为近似线性关系,横向和纵向刚度相近,弹性模量约为40 MPa.龙眼整果破壳时变形随着加载速率的增加而减小.由果壳的拉伸试验得到应力-应变关系和果壳弹性模量-应变关系.试验表明龙眼果实可看作各向同性材料.     

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。