48kW拖拉机离合器设计与分析

进行了48 kW拖拉机离合器的设计并进行了结构改进:增加一套副离合器操纵系统,节省驾驶员的体力;开有梯形槽的碟形弹簧在制造过程中易产生应力集中,把梯形槽改为弧形槽使离合器寿命大有提高。     

拖拉机离合器设计与研究

介绍了拖拉机离合器的设计理论,进行了离合器的改进。开有梯形槽的碟形弹簧在制造过程中易产生应力集中,本文把梯形槽改为弧形槽使离合器寿命大有提高;目前石棉有机摩擦材料和金属陶瓷摩擦材料在高温段的摩擦力矩均不稳定,本文在石棉有机摩擦材料中加入一定比例的陶瓷粉末,试验证明其抗高温性能高于前二者。     

拖拉机离合器的发展与研究

介绍了拖拉机离合器的发展。同时,进行了离合器的改进：开有梯形槽的碟形弹簧在制造过程中易产生应力集中,把梯形槽改为弧形槽使离合器寿命提高;石棉有机摩擦材料和金属陶瓷摩擦材料在高温段的摩擦力矩均不稳定,在石棉有机摩擦材料中加入一定比例的陶瓷粉末。试验证明,其抗高温性能高于前二者。     

东风300拖拉机独立操纵式双作用离合器设计

根据东风300拖拉机离合器开发实践,就公用碟形弹簧独立操纵式双作用离合器的结构型式、功能要求、设计理论、存在问题、经济性、适应性进行了分析总结,提出需研究解决的课题,探讨拖拉机离合器技术的发展.     

离合器碟形弹簧的计算机辅助设计

采用内点惩罚函数法寻求最优值，以离合器摩擦片磨损后碟形弹簧的工作压力变化最小为目标函数对其进行优化设计。     

电液伺服离合器碟形弹簧试验台

在介绍电液伺服离合器碟形弹簧性能试验台测控原理和基本构成的基础上 ,阐述了其硬件系统和软件系统的组成和功能。它适用于碟形弹簧生产线上产品的最终检验和拖拉机离合器装配线上碟形弹簧性能的检验。     

一种新型拖拉机用独立输出双作用离合器

目前在大功率拖拉机传动系中，广泛应用双作用离合器将发动机动力传递分流，一部分传给传动系以驱动车轮行驶；另一部分传给动力输出轴驱动农机具作业。新型独立输出双碟簧离合器设计是针对目前大功率拖拉机离合器的使用特点及离合器主要失效模式，对独立操纵式双作用离合器进行设计优化及提升，通过对离合器结构的创新设计，主、副离合器各用一个碟形弹簧，实现工作压紧力的独立控制，可有效避免用户误操作而导致的离合器打滑、烧片、分离不彻底等现象，提高离合器可靠性和寿命。     

东方红LF90系列拖拉机用离合器

<正>东方红LF90系列拖拉机是中国一拖集团有限公司80年代引进意大利FIAT公司的轮式拖拉机,它采用独立式动力输出,需要有结构紧凑的双作用离合器.该机采用开槽碟形弹簧离合器,在此对该机离合器310DL2作一分析,以利于在拖拉机及工程机械上推广应用.1 结构分析该离合器是具有主、副离合器的独立式双作用离合器,它有两个从动盘和两个同轴线的从动轴(其中一个为空心轴),一个为主离合器轴,一个为副离合器轴(动力输出离合     

山东-180型拖拉机离合器碟形弹簧优化设计

碟形弹簧如图1所示。由于其结构紧凑，加压均匀，操纵省力，并且在摩擦片磨损后，其工作压力变化较小等特点。因此广泛用在拖拉机离合器中。山东-180型拖拉机离台器就采用了碟形弹簧。     

小四轮拖拉机离合器可靠性的分析与改进

针对近年来小四轮拖拉机普遍存在平均故障间隔时间（MTBF）短的问题,课题组进行了统计分析,确认离合器是薄弱环节。选择碟形弹簧离合器取代圆柱螺旋弹簧压紧离合器,运用参数优化、三维数字化设计、有限元分析（FEM）和数字化虚拟样机（DMu）运动模拟等技术,有效地解决了这一关键问题并实现产业化。     

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.     

车用发动机润滑油失效规律与更换周期研究

研究在正常使用条件下１０Ｗ／３０－ＱＣ级润滑油用于某型车用发动机时所表现的失效规律,确认期服从两参数Ｗｅｉｂｕｌｌ分布,并给出分布的尺度参数η和形状参数ｍ之最佳线性无偏估计（ＢＬＵＥ）同时,还为定量分析,计算车用发动机润滑油的使用可靠性和合理确定其更换周期提供了一套可供借鉴的方法,并给出了具体的计算实例。     

农村剩余劳动力就业问题的探讨

论述了我国农村剩余劳动力就业的意义，并针对我国农村剩余劳动力的现状，提出多渠道促进农村剩余劳动力就业的途径和办法。     

乡（镇）农业技术推广体系存在的问题及对策

乡（镇）农技推广体系是农业发展的关键。介绍朝阳市农业技术推广体系的现状,针对目前体制及运行机制、服务手段等方面存在的问题,提出适合朝阳市乡（镇）农技推广体系改革与发展的对策,以期对全省农技推广体系改革和发展起到一些借鉴作用。     

草莓的采收与贮藏

草莓果味酸甜爽口,营养价值高,为人们所喜爱的应市鲜果之一。由于草莓易受损伤和微生物侵染,因此其采收、贮藏过程极为重要。介绍草莓采收过程中的注意事项以及11种贮藏保鲜技术的实施步骤和操作方法,推介9种加工方式,为草莓产业化提供技术支持。     

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。     

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。     

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.