刨煤机工作面初采初放新工艺的研究与应用

根据马兰矿刨煤机工作面初采初放工作的特殊性,阐述了对工作面初采初放工艺的改进。     

犁式滑雪转弯膝关节软骨有限元分析

随机挑选200名实验对象,记录他们的基本信息、关节角度和滑行速度,对其中181个有效数据进行分析.根据1名志愿者的MR,CT数据建立了膝关节140°软骨与骨的三维模型.根据运动学分析结果和膝关节解剖学结构定义载荷及约束,在Abaqus 6.14中得出转弯膝软骨应力集中出现的位置.研究结果表明:体重过大、速度过快时应适当增大转弯半径以减少向心力对膝关节软骨施加的应力;犁式转弯的过弯速度应控制在3 m/s之内.     

我国西部的生态问题与退耕还林

根据中国西部由于自然和人为因素的影响,森林破坏严重,生态环境日趋恶化,经济基础薄弱,发展水平仍然较低,人均国内生产总值无怀达到全国平均水平,已严重的制约国民经济的发展和社会的安定团结的实际情况,分析了森林遭到破坏之后所造成的恶果对整个国民经济持续、快速和健康发展的影响,研究了退耕还林在整治国土中的巨大作用。     

Effects of frost action on soil physical properties of plough pan

Undisturbed soil cores of loamy clay plough pan were subjected to the treatments of freezing and thawing in laboratory. The effects of frost action on its bulk density, porosity, and hydraulic conductivity were investigated. The results indicate that freezing and thawing significantly reduced the bulk density of plough pan and increased its porosity and hydraulic conductivity. The reduction in the bulk density was closely related to the average daily soil minimum temperature and soil water content.     

中国西部退耕还林（草）面临的新问题再思考

在改革开放20余年来,我国东部得以高速发展的基础上,党和政府审时度势提出了“西部大开发”战略,但西部生态环境恶劣制约我国整个国民经济发展。2000年在长江上游和黄河中上游的西部地区大规模实施退耕还林,又把可持续发展战略演绎到了新的高度,文章在上述背景下,通过对我国西部地区生态环境恶化与退耕造林所发挥作用的探讨,结合西部自然特点和实际情况,总结了建国50年来退耕还林和种草所经历的不平凡四个阶段,分析了退耕还林（草）过程中存在的主要问题,根据西部区情提出了保护自然资源和恢复生态环境及整治大江大河的对策。     

实时测试处理系统在拖拉机田间测试中的应用

就CX-1型微机实时测试处理系统在拖拉机悬挂机组犁耕作业田间测试中的应用,阐述了应用目的、测试方法、测试结果(举例),并进行了分析。最后指出:由于这套测试处理系统不仅提供可信的测试数据,而且能迅速、实时地得到结果,因此,可为拖拉机悬挂犁耕机组的改进设计提供一种实况测试手段.     

Effect of trash board on moldboard plough performance at low speed and under two straw conditions

Draught requirement is an important parameter for tillage tool performances. This study investigated the influence of trash board on the performance of moldboard plough and the system optimization. Draught and vertical forces acting on the plough were measured with and without a trash board under two straw conditions, i.e. with only stubbles and with dense straw cover. Field soil moisture content was kept at 30%. The study also used the finite element method (FEM) to simulate stress distribution on the plough. Results showed that draught significantly increased without trash board under dense straw cover as compared with only stubbles. The trash board attachment reduced draught significantly. Similar trend was also true for vertical force. FEM results were found to be compatible with the experiment. The simulated maximum equivalent stress acting on the mouldboard plough was 279.43 MPa, while the material’s yield stress was 250 MPa. Attaching trash board with the moldboard plough is important where straw cover was dense.     

中国古耕具的起源和演变

本文指出长期以来对中国古耕具“耒耜”的一种误解。古籍《周礼·考工记》所载,弯曲如“S”形之木耒,并非锹、镐之曲柄,而是一种“原犁”,一种没有犁辕的,以绳索牵引工作的“无辕古犁”。它是由锹到犁的过渡农具。     

不锈钢带材表面翅成形的研究

研究了正犁削不锈钢表面翅成形的加工机理，探索了形成规则翅片的刀具几何参数及犁削条件，着重对翅的形成过程进行了分析，并建立了数学模型，理论分析和实验结果表明，翅的形成过程包括导入，犁切堆积及成翅三个阶段，而犁切堆积阶段是翅形成的关键，翅的高度随犁切深度的增加而增大，且翅高比犁切深度大。     

地表覆盖对季节性冻融土壤温度影响研究

基于季节性冻土分布区冻融期间土壤温度的田间试验,研究了地膜覆盖、地膜与秸秆双重覆盖对冻融土壤剖面温度的影响。结果表明:地膜覆盖对试验土层有明显的增温效应,而地膜、秸秆双重覆盖对土壤增温的影响只限于耕作层内;越冬期试验土层范围内,各处理地块的地温均经历降低、趋于稳定、升高的过程;地膜、秸秆覆盖可平抑土壤温度变化,明显缩小温差;在冻结阶段和融化阶段,三种处理地块40~100 cm深度处地温降低和升高的幅度随深度的加大而减小。研究结果对于改善季节性冻土区土壤热状况,指导农业生产具有实际意义。