两种计算零件耐磨寿命及其可靠性方法的差异探讨

在机械零件可靠性工程方面,零件耐磨寿命及其可靠性的两种计算方法是:(1)按磨损量(W)正态分布预测在一定容许磨损条件下的可靠度为     

车辆加速寿命试验加速系数的探讨

用随机过程理论研究车辆故障的规律,提出了用非时齐泊松过程模型中的威布尔过程模型来描述车辆故障的函数。提出了车辆在加速寿命试验和实际使用情况下的可靠性等价条件,并在此基础上推导出车辆加速寿命试验加速系数的计算方法。根据车辆的加速系数随行驶里程而变化的规律,提出了加速系数函数、当量里程、当量加速系数的概念及计算方法。     

硼铸铁活塞环

近年来我国自行设计制造了大量的90、95柴油机,遍及农业生产第一线。在使用过程中,普遍反应低铬钼活塞环的寿命较低。其主要问题是早期串油和不耐磨,两者又引起恶性循环。为此上海活塞环厂和洛阳拖拉机研究所共同阶作,试验了一种新的活塞环材料——加硼铸铁。经二年来的工艺试验和装机使用试验,看来是一种有前途的活塞环材料。目前正在进一步试验,探讨和完善其制造工艺,提高使用寿命。     

4125柴油机曲轴可靠性分析

以4125柴油机曲轴的疲劳寿命试验为依据,对该柴油机曲轴进行了可靠性分析与研究.     

国产190A型柴油机系统可靠性寿命试验研究

应用可维修系统随机故障过程模型理论，对国产190A型柴油机进行了可靠性寿命试验。提出并论证了柴油机系统可靠性寿命分布规律，建立了柴油机系统在早期故障期、偶然故障期、耗损故障期的寿命模型。提出了柴油机可维修系统在整个寿命期内其故障曲线为典型的溶盆曲线，同时给出了上述3个典型故障寿命阶段的可靠性指标。     

联合收割机结构可靠性评定与寿命预测

从部件试验的寿命评定、寿命可靠性计算、结构系统的寿命可靠度三方面对联合收割机结构寿命可靠性评定与寿命预测问题进行探讨;提出联合收割机寿命估算流程与结构寿命部位确定方法;给出4LZ-3纵向轴流联合收割机当量寿命计算结果。     

X195柴油机的质量控制

本文介绍了控制X195柴油机主要性能和寿命的关键技术、改进措施及其试验研究结果在批量生产中应用效果,并提出了进一步提高X195柴油机性能和寿命的设想。     

油泵最大供油量和负荷对单缸柴油机加速烟度的影响

中国是单缸柴油机生产和销售大国,单缸柴油机在2010年国内销售量达600多万台,其给用户的普遍现象是容易冒黑烟,因此研究其加速烟度的影响因素,对进一步提高传统单缸柴油机的品质有着重大意义。1.试验目的主要研究单缸柴油机在进气流量一定条件下,油泵最大供油量即油量校正器的限油位置和负荷对柴油机加速烟度(消光烟度)的影响。2.试验条件     

柴油机三大精密偶件密封性对供油特性的影响

柴油机喷油泵的柱塞、出油阀和针阀这三大精密偶件的磨损程度直接影响到柴油机的供油规律和各种综合性能。为此,采用二次回归正交设计的方法,通过大量的试验数据,建立了精密偶件的磨损量与供油量之间的定量关系式,从而更直观、清楚地了解到三大精密偶件的密封性对供油量影响程度的主次关系。     

柴油机曲轴的疲劳寿命估算

影响曲轴疲劳寿命有很多原因,而且准确地估计出曲轴疲劳寿命的难度较大。现以某型柴油机组成的动力装置为原始模型,运用有限元模型分析的方法计算柴油机曲轴在一个周期的动态应力,再用这个周期的应力载荷谱结合疲劳计算方法分析曲轴疲劳寿命。结合不同理论下的曲轴疲劳寿命,比较后得出适合的方法。     

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。