基于效率优化的履带车辆再生制动控制策略

以履带车辆静动液辅助制动系统为研究对象,对液压泵/马达的性能进行了理论和数值分析,获得了液压泵/马达的效率曲线,在此基础上,根据液压泵/马达的效率最优原则,提出了基于液压泵/马达效率最优的再生制动控制策略。仿真结果表明,所提出的再生制动控制策略,在保证整车安全制动的前提下,使液压泵/马达工作在高效率区,实现了液压泵/马达的高效率工作,可进一步提高整车制动能量回收率。     

电动装载机电液复合制动协同控制策略研究

针对电动装载机的电液复合制动系统,为满足多工况制动需求以及保障制动安全性,本文提出了一种基于再生制动自由行程液压制动阀的电动装载机液压制动系统。结合电动装载机的理想前后轮制动力分配曲线以及制动意图识别得到的制动强度,制定了制动强度与整车制动力矩需求的分配曲线;为进一步提高再生制动力与液压制动力分配的协调性,同时兼顾制动能量回收效率,提出了一种基于行走再生制动和液压制动的电液复合制动协同控制策略,降低了整车总制动力矩波动,保证了制动模式切换的平顺性。最后,搭建了基于AMESim-Matlab/Simulink联合仿真模型,并搭建试验样机,验证了电动装载机复合制动协同控制策略的可行性,结果表明,该系统能量回收效率可达71.6%,制动回收率可达44.5%,一个工作循环实现节能7.6%,说明本文提出的控制策略具有良好的制动性能和能量回收效率。     

后驱并联式液压再生制动汽车制动力分配研究

介绍了一种后驱并联式液压再生制动汽车的基本结构,分析了液压再生制动的基本原理和整车制动控制器的工作过程,提出了一种基于制动强度、车速、理想制动力分配曲线和ECE制动法规的制动力分配策略,包括前后轮制动力的一次分配和后轮制动力的二次分配。在MATLAB/Simulink环境下建立了整车制动仿真模型,并进行了仿真分析。分析结果表明,在城市轻度制动工况下,车辆的制动能量利用率较高,验证了所提出的控制策略的正确性。     

轮毂电机驱动电动汽车再生制动控制策略

在充分考虑电机转矩特性、电池耐受性、车速、理想制动力分配I曲线、ECE法规曲线等因素的情况下,兼顾再生制动回收效率及制动稳定性,基于制动强度Z的大小分配前后轴制动力,利用Matlab/Simulink建立控制策略模型、AVL Cruice建立整车模型,并与固定比例分配前后轴制动力的控制策略进行联合仿真对比分析。结果表明,本文控制策略保证制动安全与稳定的前提下有效提高制动能量的回收效率。     

纯电动汽车制动能量回收控制策略研究与仿真

为有效地回收电动汽车的制动能量,分析了再生制动力的约束条件和电机再生制动力矩的最大限值;根据电机可提供再生制动力矩与需求的制动力矩的关系,提出了满足四轮驱动电动汽车的制动能量回收优化控制策略,利用Matlab/Simulink和Advisor软件平台进行了系统建模和典型循环工况下的仿真,仿真结果表明,该控制策略能够实现安全条件下的制动能量回收,制动能量回收效率达到22.11%。     

汽车能量再生制动技术研究现状及其关键技术

介绍了汽车电储能再生制动能量转换、能量储存及控制策略研究发展动态。在对再生制动系统软硬件研究现状分析的基础上,提出了要充分利用汽车制动能量,就要把制动能量回收与利用综合起来考虑,在保证车辆安全性能的条件下达到再生制动功能与效率的优化,并指出了当前再生制动要解决的关键技术问题。     

定压网络车辆的制动力分配策略

针对一种应用定压网络液压马达控制系统的新型电控液驱车辆的制动系统,进行了制动力分配策略的研究。制动力分配策略的基本原则是根据驾驶员的意图合理地分配能耗制动和再生制动的比例,优先应用再生制动,在再生制动不能满足要求的情况下同时应用能耗制动和再生制动。提出了一种制动系统布置方案,设计了控制器并建立了系统的数学模型。利用Matlab/Simulink进行仿真,结果表明提出的制动力分配策略可以较好地满足制动要求,并能够回收19.9%以上的能量。     

电动车辆整车制动控制技术研究

整车控制器是整车控制的核心部件,其功能按照整车控制策略做出相应判断后由CAN总线发送控制信号给电机控制器、电池管理系统和仪表显示盘,进而控制动力系统及各执行部件,驱动汽车正常行驶。为最大限度地降低能量消耗,提高制动能量回收率,基于整车性能指标要求,从再生制动控制、驱动转矩管理等方面开展研究,提出复合制动策略,在轻度和中度制动情况下,提高能量管理效率和续驶里程,满足整车要求。     

电动汽车再生制动模糊控制策略与优化研究

以电动汽车制动能量回收系统为研究对象,分析了影响制动能量回收的各因素,在此基础上提出了基于模糊控制的再生制动控制策略,在SIMULINK中建立了该控制策略的仿真模型。并应用遗传算法对该控制策略的隶属度函数进行了优化,将其嵌入到ADVISOR再生制动控制策略中,分别在美国公路UDDS,美国市区模拟循环FTP,欧洲公路EUDC和日本的1050工况下与ADVISOR中的再生制动策略进行对比。分析汽车的续驶里程以及工况循环下能量回收总量,以证明该策略以及优化后策略的有效性。     

基于电磁机械耦合再生制动系统的电动汽车稳定性控制

针对现行电动汽车再生制动的不足,提出了一种电磁机械耦合再生制动系统,以克服摩擦制动和再生制动相互独立控制的缺点。在此基础上,以内嵌侧向力约束的二自由度车辆模型为参考模型,基于直接制动输入分配和模糊补偿控制提出了一种集成再生制动的电动汽车稳定性控制策略。以美国FMVSS126法规为试验工况和评价指标,以及低附路面阶跃转向工况为例,应用Matlab/SimulinkCar Sim车辆动力学仿真试验平台,对有、无模糊补偿控制的侧向稳定性、操纵响应性和能量回收率等进行对比分析。研究结果表明,有模糊补偿控制的车辆顺利通过法规测试,所提出的模糊补偿稳定性控制策略具有很好的鲁棒性和横摆稳定性,减小了横摆角速度和质心侧偏角的跟踪误差,即增加了行车安全性,又具有一定的制动能回收率。     

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。