液压互联消扭悬架系统研究

根据悬架约束最小化原理,提出一种液压互联消扭悬架系统,阐述了该系统的结构与原理,构建了液压互联消扭悬架系统模型及整车动力学模型,分析了各种工况下液压互联消扭悬架动态性能,设计液压互联消扭悬架原理样机,进行台架试验,仿真与试验结果基本一致。结果表明:与传统被动悬架相比,液压互联消扭悬架能有效抑制车身振动,控制了车身姿态,协调了车辆的行驶平顺性与安全性,提高了车辆极端路况的路面通过性能,消除了部分车身扭转载荷,并能实时控制车辆的转向特性。     

车辆电动静液压半主动悬架设计与馈能研究

为了实现车辆悬架的减振控制及振动能量回收,提出并设计了一种基于电动静液压作动器(EHA)的车辆半主动馈能悬架结构。建立了2自由度半主动悬架力学模型以及EHA作动器的数学模型;设计了EHA作动器,进行了电机特性试验和EHA作动器的馈能试验;设计了EHA半主动悬架最优控制和能量管理控制策略,利用AMESim与Matlab/Simulink软件对EHA半主动悬架动态性能和能量回馈进行了仿真;设计了EHA半主动悬架试验测试系统,开展了EHA半主动悬架控制台架试验。仿真与试验结果表明,提出的EHA作动器馈能效果较好,馈能效率平均为50%左右;与被动悬架相比,在正弦激励和随机路面谱输入下EHA半主动悬架的簧载质量加速度下降20%左右,减振效果明显。     

三元件并联ISD悬架的减振特性探究

文章主要对三元件并联结构的车辆被动ISD悬架减振特性进行分析。采用惯容器理论结合传统被动悬架功能的性能改进的方法,在车辆被动蓄能悬架系统的机械元件设计结构设计和技术应用等方面,初步对悬架系统的惯容器、弹簧、阻尼的三元件串并联结构进行论述。运用统一目标函数的多目标遗传算法,对最佳三元件结构中惯容器和阻尼串联后弹簧并联结构进行系数的计算,建立了结构的1/4询价模型。     

基于MATLAB/SIMULINK的油气悬架动力学仿真

建立了单气室油气悬架的非线性数学模型和二自由度汽车振动模型,利用蒙特卡洛法构造了路面不平度时间函数,利用MATLAB/SIMULINK进行了时域仿真。分析了油气悬架主要参数包括蓄能室初始体积、主活塞杆面积、阻尼孔面积变化对车辆平顺性、安全性的影响,得出了某型油气悬架结构参数的可行设计范围。     

车辆半主动空气悬架系统设计与试验

建立了半主动空气悬架系统数学模型,设计了可调阻尼减振器、半主动悬架控制器以及台架试验系统。在仿真的基础上,进行了可调阻尼减振器试验与半主动空气悬架系统1/4模型台架试验,分析了半主动空气悬架及其控制系统对车辆动态性能的影响,计算和试验结果基本吻合,提高了车辆的乘坐舒适性。     

基于二自由度车辆模型的悬架性能研究

以二自由度车辆模型为研究对象,基于车辆动力学和现代控制理论,研究车辆悬架系统的性能.在Matlab/Simulink里建立二自由度车辆振动和随机不平路面仿真模型,进行随机路面输入的平顺性仿真试验,并分析了悬架刚度、阻尼系数及轮胎刚度对悬架性能的影响,得出车身加速度、悬架动挠度、轮胎动载荷随悬架刚度、阻尼系数及轮胎刚度变...     

四分之一车辆悬架系统的动力学仿真分析

首先建立了四分之一车辆悬架系统的数学模型,应用MATLAB/Simulink软件建立该系统的仿真模型,并对此系统在白噪声、坡、台阶3种不同路面输入下车身加速度、轮胎动载荷和悬架动行程的仿真结果进行比较分析,得出了过特殊路面车辆操纵稳定性和乘坐舒适性下降的趋势。最后分别仿真研究了悬架单个参数和两个参数综合对悬架各性能指标的影响,为悬架系统参数的优化设计提供了一种有效的参考方法。     

基于粒子群算法的车辆悬架PID控制器研究

PID控制器是应用最为广泛的控制器,可用于车辆半主动空气悬架的控制,但是,传统的PID控制器参数整定方法需要丰富的工程经验和大量试验。因此,本文提出运用粒子群算法对PID控制器参数进行整定从而提高PID控制器设计效率。首先,建立1/2车辆半主动空气悬架系统数学模型,并在Simulink环境下搭建带有PID控制器的仿真模型。然后,进行粒子群算法优化PID控制器的仿真试验。仿真结果显示,与被动悬架系统相比,在B、C两种路面条件下,基于粒子群算法的PID控制器使车身质心垂向加速度均方根值分别下降25.5%和33.13%,提高车辆的乘坐舒适性。本文对用于半主动空气悬架系统的PID控制器的进一步发展具有一定积极意义。     

半主动油气悬架系统模糊控

以两自由度悬架模型为研究对象,针对半主动油气悬架系统,提出了以悬架动挠度为控制目标的模糊控制策略,并对系统进行仿真和实车道路试验.结果表明,采用模糊控制的半主动油气悬架在衰减车辆振动、提高车辆行驶平顺性方面优于传统被动油气悬架.     

连通式油气悬架升降同步控

提出了一种基于调速阀和压力跟随元件的改进型连通式油气悬架系统.利用调速阀和压力跟随元件的有效组合,完成了系统刚柔性状态间的平稳切换,实现了大型工程车辆整车的同步升降.建立油气悬架系统AMESim仿真模型,对变负载工况下系统同步升高进行了仿真.搭建相关试验台,对该改进型系统进行试验研究,其升高过程的同步误差小于2.5mm,刚柔性状态切换平稳,悬架缸无抖动现象.试验与仿真结果吻合,既验证了改进型连通式油气悬架系统的可行性,又验证了仿真模型的正确性.     

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。