玉米收获机夹持输送装置的研究

夹持输送装置是穗茎兼收型玉米收获机的关键部件。为了解决玉米植株在夹持输送中的断茎、堵塞等问题，对夹持输送装置的关键部件进行研究，通过增设输送拨禾链，从而有效地地解决了上述问题。     

谷物收获超声波流量计的前期研究

以多普勒法的谷物收获超声波流量计为研究对象,进行谷物收获系统和超声波流量计的前期研究.超声波流量计是利用流体对超声波的影响来测量流量的仪表,传统的测量原理一般为时间差法,测量精度低,只能对液体或者气体进行流速测量;而采用多普勒测量法则可以达到更高的测量精度,并且尝试对谷物(固体)的流速进行测量.     

水分亏缺对覆膜玉米生长发育及产量的影响

通过系统的覆膜玉米亏水灌溉试验 ,研究了不同生育期内不同程度的水分亏缺对覆膜玉米生长发育、光合作用、产量及水分利用效率等的影响。结果表明 ,拔节期受旱对玉米株高及叶面积指数影响最大 ,抽雄后的水分亏缺对玉米生长发育影响不明显。各处理产量资料表明 ,覆膜春玉米的需水临界期为抽雄开花期 ,此期轻度的水分亏缺可造成产量大幅度下降 :灌浆期较抽雄开花期玉米产量对水分亏缺敏感程度低 ,但在这个阶段的水分亏缺也可使玉米减产 ;拔节期玉米产量对水分胁迫敏感程度较差 ,该阶段为对玉米进行水分亏缺处理的适宜时期     

不同节水灌溉技术的节水机理试验研究

根据甘肃省特殊自然地理条件，对于喷灌、滴灌、渗灌及波涌灌几种方式下，小麦和玉米两种作物的灌溉节水机理进行了对比试验研究，分析了不同节水灌溉方式下这两种作物的节水性和生育动态。试验结果表明，在降雨、灌溉水量和前期土壤特性一定的情况下，在喷灌、滴灌、渗灌及波涌灌几种节水灌溉技术中，渗灌的节水性最好，依次为滴灌、喷灌、波涌灌。小麦和玉米在渗灌条件下产量比滴灌、喷灌和波涌灌都高，小麦渗灌产量比滴灌增加7．6％，比喷灌增加13．1％，比波涌灌增加22．4％。玉米渗灌产量比滴灌增加1．3％．比喷道增加6．3％。     

支持向量机在水质评价中的应用

介绍了支持向量机算法的原理，建立了基于支持向量机的水质评价多层次分类检测模型，通过提取水质评价标准中的物质成分为特征参数，利用几个SVM分类器的串联组合，实现对水质的分类和识别，同时，引入类权重因子，解决训练样本类别数量不平衡而导致的错分问题，实验结果显示该方法提高了水质评价的准确性和效率。     

中南地区甜玉米丰产栽培技术

本文从土地选择、品种选择、怖种与育苗、田间管理、病虫害防治、适时收获等六个方面,总结了中南地区甜玉米的丰产栽培技术.     

灌区运行状况综合评价权重系数的确定

由于主观赋权法确定的权重系数与评价者的知识结构及偏好有关,它存在较浓的主观色彩,为了避免这种弊端,利用客观赋权法拉开档次法来确定权重系数,并用于灌区运行状况的综合评价。"拉开档次"法直接利用评价对象评价指标的实际观测值来确定权重系数,这种方法在整个评价过程中无人为的干扰,这将更能体现评价结果的真实性、可靠性与合理性。通过某灌区实例分析可知该方法可靠、分析结果合理,可为灌区运行评价提供科学依据。     

Effect of drying on soil strength and corn emergence

Summary Laboratory studies were conducted to evaluate the effects of drying on soil strength and corn emergence (Zea mays L.). Corn was germinated in Billings silty clay under a bank of heat lamps which operated 9, 14, 19, or 24 h per day. Soil strength (modules of rupture), soil moisture content and emergence were measured daily.The relationship of soil strength to corn seedling emergence as influenced by the four light and heat durations and bare and mulched soil surfaces was determined. As soil strength increased emergence decreased until it ceased at soil strengths of about 80 kPa. Strength of this soil had a high negative correlation with soil water content and increased with time. Mulching decreased initial rate of drying, decreased crust strength, and improved corn emergence. The 14-hour light and heat treatment resulted in the highest corn emergence.Contribution from Colorado State Experiment Station, USDA-ARS Snake River Conservation Research Center, and USDA-ARS Fort Collins, respectively     

The effect of salinity on corn yield using the CERES-maize model

In most cases, when calculating soil water availability, only thewater content is considered. The effect of salinity on the wiltingpoint is neglected. The objective of this work is to use asimulation model (CERES-maize) in order to predict cornyields as a function of water salinity under severalenvironmental, agrotechnical, and plant characteristics. A modelis presented in which the wilting point is a function of the soilsalt content. At high salinity, the water content at wilting pointis higher than at low salinity, resulting in an insufficient amountof available water and, therefore, a reduced yield. The modelwas used to simulate several theoretical and experimentalsituations for forage corn and grain corn. Simulation resultsshowed that nitrogen fertilization increases the salinity thresholdvalue and the yield sensitivity (rate of yield reduction per unitof salinity). The also showed that forage corn is more sensitiveto salinity than grain corn. If the soil is not leached, a heaviersoil texture has a higher salinity threshold value. On the otherhand, if the soil is leached, the soil texture has no influence onthe salinity threshold value and the yield is less sensitive tosalinity in sandy soils. The determination coefficient (r²= 0.75) indicated that the results of the simulations were in goodagreement with the field data.     

水质模糊评价的探讨

首先建立了利用模糊数学对水环境评价的模型，并在模糊综合评价中就各污染因素对整个水环境污染的作用进行了定量分析，进一步客观的进行评价。在计算权重时充分考虑污染因子在数量和性质方面对权重的作用。在多污染因子影响的水环境评价中，通过对污染因子按其属性及其评价目标进行了集合，这样可更真实地反映各因子之间的关系以及对整个污染的作用。