神经网络方法在车内噪声信号预测中的应用

针对以往车内噪声有源控制过程中存在的次级声源在初级声场采样传声器上的声反馈问题，提出了车内噪声信号识别和预测的神经网络方法。对被试面包车在稳态和非稳态两种工况下的试验研究表明，利用车身悬置点和发动机的振动信号，通过BP神经网络来识别和预测车内驾驶员耳旁噪声是可行的，可以解决次级声源在初级声场采样传声器上的声反馈问题。     

车内噪声分析与控制研

利用互易性原理,提出了一种空气声传播路径实验方法.首先测得各声源对于车内噪声的传递函数,进而得到各声源对于车内噪声的贡献度.根据声源识别结果,对汽车车身进行吸声、隔声设计,结果表明,车内地板隔声量从前向后分别提高了1.83～9.74 dB(A),汽车车内噪声下降了4.7 dB(A).     

发动机排气噪声有源消声技术研究

排气噪声是发动机主要的噪声源之一。有源消声技术是运用数字信号处理技术实现声波相消干涉达到电控消声目的,它已成为近年来发动机排气噪声治理领域备受关注的一个热点。为此,主要研究了有源消声技术在发动机排气降噪方面的应用,并对其进行了模拟实验。结果表明,有源消声技术具有明显的降噪效果。     

基于matlab仿真模块的自适应有源噪声逆控制研究

运用matlab仿真模块对自适应有源逆控制中的两种算法:滤波-ULMS算法和改进的滤波-ULMS算法进行了仿真研究。并对两种算法的消声效果进行了比较,验证了改进的滤波-ULMS算法有着更为优越的动态性能。     

某小型SUV加速行驶车内异常轰鸣噪声分析及控制

针对某小型SUV车内异常轰鸣噪声,通过对噪声进行测试数据滤波分析和声音信号回放识别,确定车内噪声频率特征。利用噪声振动相关性分析和结构模态分析方法识别噪声声源和传播路径,并针对该小型SUV车内异常轰鸣噪声,从声源和传播途径方面提出了解决方法。分析结果表明,空调压缩机安装支架、制冷管路振动是车内异常轰鸣的主要噪声源,空调管路与车身纵梁连接点是主要传递路径。通过优化空调管路与车身纵梁的连接方式、增加隔振措施等方案,解决车内异常轰鸣噪声问题。该案例给由空调系统振动产生的车内轰鸣噪声的解决提供了思路。     

发动机排气噪声有源控制的模拟实验

发动机排气噪声是宽带噪声。在能够获得参考信号的前提下,采用白适应有源消声(Adaptive active nois econtrol,简称AANC)的前馈控制(Actire feedforward control)是有效的方法。为此,在引用Filtered—MS算法的基础上,分别对参考信号的采集和系统识别进行分析,并进行了仿真实验。     

基于车内噪声控制技术的研究

随着汽车保有量的不断增加,车辆噪声污染已经成为人们越来越关注的环境问题。本文分折了车内噪声声源机理,并针对汽车车内噪声的来源提出相应的控制技术,以达到降低车内噪声的目的。     

柴油机排气消声器发展近况

排气噪声是柴油机的主要噪声源,而安装排气消声器是控制发动机排气噪声最直接和最有效的方法.目前,消声器的研究主要包括有源消声和无源消声两类.为此,对柴油机排气消声器的设计及研究方法进行了阐述,并基于反相抵消的思想提出了一种新型主动节能型消声器的设计原理.     

基于声能量叠加法的车内噪声源分离试验研究

车内行驶噪声是直面用户的驾乘感知,其主要来自3个声源,即动力系统噪声、风激励噪声和路面行驶引起的噪声。通常认为在低速时,发动机是主要噪声源,在中速时,轮胎与路面的摩擦是主要噪声源,而在高速时,车身与气流的作用变成了最主要的噪声源。针对用户使用场景中的典型城市工况(匀速60 km/h)和高速工况(匀速120 km/h),基于风洞测试和低噪声整车传动试验台测试,进行噪声源分离,由此获得风激励单独激励下的车内噪声和动力系统单独激励下的车内噪声,随后通过声能量叠加方法精确地计算3种主要噪声源的声能量占比,并分析能量谱中各频段下3种噪声能量比重,城市工况道路噪声占比75.6%,高速工况道路噪声占比48.5%,均为车内噪声中最主要的贡献,为车内噪声控制优化和3种噪声的仿真分析对标提供可靠的依据和指导。     

新车内的异味消除

(1)放置热带水果。热带水果香味浓、所含水分多,浓重的香味可长时间地散发,是天然的汽车"空气清洁剂"。如将柠檬或菠萝切成片置放车内,对改善车内空气有奇效。(2)放置烧过的蜂窝煤。煤的主要成分为炭,而炭对气味有很强的吸附作用,放置烧过的蜂窝煤能快速的消除车内异味。此法还能除车载冰箱的异味。     

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。