带自调整装置的摩擦磨损试验机设计与试验

研制了一台带自调整装置的摩擦磨损试验机,能调整上试样的位置和状态,使摩擦面保持理想接触,并保证试验载荷作用在摩擦面的对称中心平面内,使该试验机更适合于摩擦机理研究和材料耐磨性测试。     

柴油机活塞—缸套结构的摩擦磨损实验装置设计

根据柴油机活塞—缸套结构的摩擦磨损的特性以及影响因素,设计了一套实验装置。该装置可完成在不同转速、不同温度、不同载荷下进行不同材料的活塞—缸套结构的摩擦磨损实验。     

Kevlar浆粕和冰晶石及硫酸钡在摩擦材料中的作用

分析了Kevlar浆粕、冰晶石及沉淀硫酸钡对制动摩擦材料摩擦磨损性能、洛氏硬度及冲击强度的影响.结果表明：填加Kevlar浆粕、冰晶石及硫酸钡能不同程度地提高并稳定摩擦因数、降低比磨损速率,其中Kevlar浆粕和冰晶石的混杂效应最为明显;增大硫酸钡含量则能较好地控制摩擦因数随温度的波动;摩擦材料的洛氏硬度值有所降低,而冲击强度则不同程度地提高.利用扫描电镜对摩擦材料磨损表面进行了观察和磨损机理分析.     

基于虚拟仪器的摩擦片性能测试系统

基于虚拟仪器的摩擦片性能测试系统,通过虚拟仪器技术,配以PC机平台和LabWindows／CVI软件,实现了对石墨填充PTFE材料摩擦磨损性能的自动连续测试。试验表明,该系统对材料摩擦系数的测试结果准确。该测试系统的成功设计,为石墨填充PTFE等摩擦材料的设计提供了重要的试验手段。     

悬挂农具作业动力学参数田间实时测试系统

为了满足农业机械研制过程中对多个动力学参数实时测试的需要,在分析其他测试装置及原理的基础上,将三销求和电路及测力销装置与农机通用的三点悬挂机构有机结合,研制出三点悬挂式测力装置。以LabVIEW为开发平台,针对所选传感器的特点,开发出大功率(150 kW以上)农机具动力学参数田间测试系统,实现农机具的位移、动力输出轴转速和扭矩、输出功率、打滑率、水平牵引力以及油耗等参数的实时测试,研制出CTM-5000型悬挂农机具田间综合测试系统,分析了系统误差产生的根源,并找出消除误差的措施。以拖拉机前、后配套农机具为试验对象进行了田间试验,在室内与现有类似测试系统进行了比较验证,试验运行和验证结果表明本系统测量数据可靠,操作方便,体现出其设计的合理性和优越性。     

柴油机活塞环与缸套摩擦副磨损机理分析

通过摩擦磨损试验机分析了柴油机常用的4种表面功能层活塞环与4种合金铸铁材料缸套摩擦副的摩擦因数和磨损系数,结合摩擦界面形貌和成分分析,研究了不同活塞环-缸套摩擦副的磨损机制.研究结果表明,陶瓷复合镀层活塞环-缸套摩擦副具有稳定和优良的摩擦学特性,耐磨性大幅度提高;镀铬环-缸套摩擦副物理化学性质稳定,但摩擦因数和磨损系数高;喷钼环-缸套摩擦副物理化学性质不稳定,出现钼颗粒剥落和形成表面复合膜等现象,摩擦因数出现拐点,缸套和活塞环都具有最大的磨损系数.     

油润滑条件下聚四氟乙烯滑动磨损特性研究

研究了油润滑条件下的轴承密封材料聚四氟乙烯的滑动磨损特性。利用摩擦磨损试验机进行试验,并用磨损表面三维形貌重构设备和三维表面粗糙度参数等对PTFE在试验过程中的表面磨损情况进行了微观形貌分析。结果表明,在试验条件下,PTFE的主要磨损机理为磨粒磨损和粘着磨损;在试验范围内,PTFE试样的磨损体积、磨损率的变化对应着摩擦系数的变化,且与磨损机理的变化密切相关;三维表面粗糙度混合参数Sdq可以反映PTFE材料在磨损过程中的磨损表面微观形貌变化情况。     

基于虚拟仪器的水稻直播机牵引性能试验

在拖拉机配套农机具的结构设计中,牵引性能试验是验证设计合理性和优化设计的重要环节.为此,从牵引动力学理论出发,采用LabVIEW虚拟仪器技术平台,试制了一套水稻直播机牵引性能在线测量系统.试验表明,该系统能适用于低速(0～5 m/s)、附着条件差和负载波动大的水田测试,人机交互性好,结果可靠,而且采用其灵活的模块化设计和软硬件配置,可以完成诸如振动和材料磨损等附加测试.     

咸水对UHMWPE材料摩擦性能影响及微观分析

为研究超高分子量聚乙烯材料在咸水输送过程中的摩擦性能以及微观动态,采用CFT-I型材料表面性能综合测试仪在干摩擦、纯水润滑、咸水润滑3种不同摩擦环境下对UHMWPE材料试样进行旋转摩擦,通过扫描电子显微镜以及表面轮廓仪分析了转速为500 r/min,荷载为50 N,历时为25 min;转速为500 r/min,历时为10 min,荷载为30,50,70,90,110 N;荷载为50 N,历时为10 min,转速为300,500,700,900,1100 r/min等变量因素对UHMWPE摩擦磨损性能的影响规律,以及咸水润滑过程中颗粒的微观运动形态.结果表明:咸水润滑下UHMWPE磨损机制主要为磨粒磨损,其摩擦系数以及磨损量相比干摩擦、纯水润滑均最小,摩擦系数随着荷载以及转速的增大呈现先增大后减小的规律,且随时间的延长呈现下降趋势.咸水润滑在摩擦过程中形成减磨性能强的润滑膜并且析出起到滚珠作用的盐结晶颗粒,可减少UHMWPE在咸水输送中的磨耗,为UHMWPE材料在咸水环境下的应用提供了理论基础.     

农机具的磨损和抗磨技术的应用

根据农机具的磨损损坏的原因和磨损表面破坏的特征,磨损可分为:磨粒磨损、粘着磨损、表面疲劳磨损、腐蚀—机械磨损。在这四大类磨损中,以磨粒磨损最为严重。据有关资料介绍,在所有因磨损失效的零部件中,磨粒磨损占40％～50％,可见磨粒磨损对零部件的危害之大不容忽视。 部分农业机械的磨损主要是磨粒磨损。耕作机械中的犁铧、犁壁、耙片、旋耕刀片等部     

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。