阻尼减振降噪结构几何参数特性分析

分析了阻尼减振降噪结构模型中几何参数的特性及其对结构损耗因子的影响。对采用非间隔式阻尼层结构和间隔阻尼层结构几何参数进行了研究,最后对大型履带式拖拉机行走系进行了阻尼减振降噪结构的实际应用和性能对比试验分析。     

农业机械的振动问题与减振方法的研究

农业机械的振动是指机械系统中的位移、速度和加速度的震荡现象。而农业机械的振动问题严重地影响着机械的正常工作。为此，综合分析了常见的农业机械的振动问题，并提出了具体的减振方案；同时，利用实验研究的方法，对相关的措施进行了分析；比较实验结论，确定合理的优化减振方案，降低了机械的损耗。     

丘陵山地果园智能运输小车减振结构优化设计

由于丘陵山地果园路面不平坦,果实运输车减振效果差,果品因运输车的剧烈振动而损伤。为保证果品的园内运输质量,需对丘陵山地智能运输小车的减振系统进行优化设计。首先根据丘陵山地果园地形地貌,构建运输车激励图谱;通过对悬架系统进行分析,设计一种适用于丘陵山地果园运输车的二级减振结构,并对其进行参数优化;然后利用ADAMS构建动力学模型,对其减振性能仿真分析,仿真结果表明二级减振结构较单级减振结构在Z向和X向减振性能分别优化9.08%和24.22%,参数优化后的二级减振结构较优化前减振性能提高7.1%。     

履带式拖拉机橡胶减振驱动轮性能研究

针对应用大型履带工拖拉机驱动链轮的橡胶减振新技术，建立了其减振模型，推导出相应的传递率函数。在分析了各参数不同值对减振性能的影响后，提出了参数的取值必须满足减振体要求及结构约束的难点，最后还进行了实例计算。     

基于变密度法的约束阻尼结构拓扑优化研究

约束阻尼结构拓扑优化是轻量化设计要求下实现噪声与振动控制的关键技术。采用有限元方法建立约束阻尼结构的动力学有限元模型。基于实体各向同性材料惩罚(SIMP)插值方法,以模态损耗因子最大化为目标,约束阻尼材料用量为约束,构建约束阻尼结构的拓扑优化模型。利用伴随向量法推导了目标函数对设计变量的灵敏度,通过优化准则法对优化模型进行求解。数值结果表明:优化后约束阻尼板结构的模态损耗因子提高比基本在50%以上,且振动振幅值有明显抑制。     

深孔钻杆系统扭振动力减振器优化及仿真研究

在深孔钻削过程中,钻杆容易产生扭振,在钻杆支架上安装动力减振器,可以有效抑制钻杆的扭振。首先简化深孔钻削系统扭振减振模型,建立钻杆系统的动力学方程,再用一加工实例来说明系统中各项参数的确定,以及动力减振器的结构参数的设计并对各项参数进行优化,最后利用Simulink软件对附加动力减振器前后的钻杆系统进行动力学仿真对比,结果表明经过优化的动力减振器取得了良好的减振效果。     

汽车半主动悬架的多目标遗传优化

汽车采用磁流变液减振器，可根据不同的道路行驶条件，通过改变磁场强度来改变减振器的阻尼特性。提出了一种多目标汽车半主动悬架的遗传优化技术，以行驶安全性、乘坐舒适性、结构空间需要作为优化设计目标或约束，选择悬架系统阻尼作为优化参数，以一个受路面谱激励的1／4汽车模型为例，采用一种高效十进制遗传算法对半主动悬架的减振效果进行验证，结果表明该遗传算法对汽车半主动悬架的参数优化具有较好的效果。     

车内相似耦合声场的设计参数灵敏度分析

建立了由汽车发动机室和驾驶室组成的相似耦合声场模型,应用统计能量法分析了发动机室能量自损耗因子和防火墙隔板厚度对各子系统空间声能的影响,并通过灵敏度分析进一步揭示了各子系统的空间声能随发动机室能量自损耗因子和隔板厚度变化的特性,为汽车设计阶段的参数优化提供了参考依据.     

小型耕整机阻尼减振手把的虚拟仿真试验

提出了一种小型耕整机的阻尼减振手把,建立了虚拟样机并采用仿真正交试验对其参数进行了优化。通过建立2种作业条件下的虚拟样机及仿真,研究了阻尼减振手把的减振效果,给出了阻尼减振手把粘性流体的仿真试验方法。研究结果表明,阻尼减振手把能有效降低手把的振动量,加速度降低49%~81%。     

振动压路机减振系统研究

振动压路机的减振性能对工作可靠性、操作舒适性、零件的使用寿命、噪音有直接的关系,本文通过理论分析、动态仿真相结合的研究方法,从理论上介绍了振动压路机的减振原理,介绍了振动压路机减振性能的评价方法,通过参数动态仿真对振动压路机减振系统进行了动态性能研究。研究得到的一些数据及相关结论,对进一步优化振动压路机减振系统的设计是十分有益的。     

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.     

农村剩余劳动力就业问题的探讨

论述了我国农村剩余劳动力就业的意义，并针对我国农村剩余劳动力的现状，提出多渠道促进农村剩余劳动力就业的途径和办法。     

车用发动机润滑油失效规律与更换周期研究

研究在正常使用条件下１０Ｗ／３０－ＱＣ级润滑油用于某型车用发动机时所表现的失效规律,确认期服从两参数Ｗｅｉｂｕｌｌ分布,并给出分布的尺度参数η和形状参数ｍ之最佳线性无偏估计（ＢＬＵＥ）同时,还为定量分析,计算车用发动机润滑油的使用可靠性和合理确定其更换周期提供了一套可供借鉴的方法,并给出了具体的计算实例。     

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。     

乡（镇）农业技术推广体系存在的问题及对策

乡（镇）农技推广体系是农业发展的关键。介绍朝阳市农业技术推广体系的现状,针对目前体制及运行机制、服务手段等方面存在的问题,提出适合朝阳市乡（镇）农技推广体系改革与发展的对策,以期对全省农技推广体系改革和发展起到一些借鉴作用。     

草莓的采收与贮藏

草莓果味酸甜爽口,营养价值高,为人们所喜爱的应市鲜果之一。由于草莓易受损伤和微生物侵染,因此其采收、贮藏过程极为重要。介绍草莓采收过程中的注意事项以及11种贮藏保鲜技术的实施步骤和操作方法,推介9种加工方式,为草莓产业化提供技术支持。     

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。