碳纤维复合材料层合板压延筋设计与优化

为满足结构轻量化的需求,碳纤维复合材料的使用越来越普及,综合采用轻量化材料和结构优化设计技术,提出一种碳纤维复合材料层合板压延筋设计方法。新型结构在考虑复合材料结构模具成型方式的前提下,利用形貌优化设计方法在复合材料层合板成型过程中布置类似压延筋结构,以提高层合板结构刚度和稳定性,然后通过碳纤维层合板的优化设计,提高结构整体刚度,降低层合板质量。结果表明,新型层合板结构使平板整体刚度增加了97.84%,提升效果明显,压延筋结构形式在层合板中的应用效果显著。     

多筋塑料盒注塑模具筋位电极设计方案研究

以某多筋塑料盒零件为例,简述对多筋类零件注塑模具筋位的加工方案、电火花成型加工在模具筋位加工中的应用,以及筋位电极常规设计方案;并重点介绍一种优化镶拼结构的筋位电极,这种电极是由两种材料镶拼而成的,该设计可以有效降低生产成本,减少切削加工量和材料浪费。     

基于刚度的铝质发动机罩优化设计

通过使用轻质材料代替钢材合理设计汽车零部件来减轻汽车质量可以达到降低燃油消耗、减小排放污染的目的。本文介绍了使用铝合金材料代替传统的汽车用钢材设计发动机罩。借助有限元软件基于刚度对铝质发动机罩进行了尺寸优化设计并提出了一种改进方案。在满足刚度的同时静态强度和固有频率都有了很大的提高并达到了较好的减重效果。     

连续体结构与支撑综合拓扑优化设计方法

针对标准结构拓扑优化时支撑边界条件预先给定不变的情况,将支撑作为设计变量参与优化过程,提出了一种基于SIMP的结构与支撑综合拓扑优化设计方法.这种方法被应用到最小柔度的刚度拓扑优化设计中,进行了二维数值实验,并讨论了成本系数、弹簧原始刚度和中间支撑密度单元对结构拓扑优化分布的影响.     

风电机端盖缩孔和缩松缺陷的探讨与消除

由于电机端盖复杂的壁厚变化,导致铸件在试生产中产生严重的缩孔、缩松缺陷。针对这一问题,对其进行了工艺分析与改进,介绍了消除该类缺陷的工艺方法:冒口系统的优化并添加发热块、铸件补贴工艺的调整、炉料配比的优化设置、铸型刚度的优化等工艺措施,并利用模拟软件JSCAST对改进工艺进行验证、优化,有效消除了端盖严重的缩孔、缩松缺陷。     

白车身概念模型的扭转刚度优化方法

以扭转刚度为优化目标,运用敏感度分析和正交分析相结合的方法,进行优化设计。以梁、接头和壳体为组成部分,建立了白车身简化模型和有限元模型,并通过与详细模型的对比,验证了模型的可靠性。优化影响扭转刚度的关键因素,如梁的截面、接头刚度和壳体厚度等信息。通过分析,可以提供理想的优化方案。     

一种氢燃料电池运输车车架有限元分析

以某氢燃料电池运输车车架为研究对象,对现有底盘燃料罐的布置方式进行优化,提出了将原来在车架上方的燃料罐布置到车架两侧的方案,采用有限元建立原车架模型和优化后车架模型,对两种车架的典型工况进行有限元分析。结果表明,优化后车架强度既满足设计要求,也不会产生共振,符合该运输车设计要求。这种车架的布置方法不仅可以规避原方案中燃料罐占据较大空间的弊病,还可以扩大载货使用空间。     

拖拉机液压机械无级变速器箱体的轻量化设计

以一款拖拉机液压机械无级变速器箱体为研究对象,提出了基于折衷规划多目标拓扑优化方法的箱体轻量化设计方案,同时考虑固有频率和箱体刚度对箱体进行轻量化设计。基于优化结果对变速器箱体进行详细设计,通过在轴承座孔上施加加强筋,降低该区域的最大集中应力值,以达到兼顾箱体轴承座结构刚度强度和减轻箱体质量的目的。研究结果表明:优化后的变速器箱体质量为243. 4kg,较初始箱体质量418. 2kg降低了41%;优化后箱体的最大位移为0. 158 mm,较初始设计箱体的最大位移0. 219 mm降低了23%。     

基于机床刚度特性的床身结构优化设计

床身是机床结构的重要组成部分,对机床整机的刚度特性具有重要影响。本文以某数控机床床身为研究对象,通过对机床床身刚度的优化设计的必要性进行论述,在对其结构进行静动态分析的基础上,提出了几种基于机床刚度特性的床身结构优化设计方案,主要包括基于有限元法的结构优化,基于OptiS tructure的拓扑优化,构件尺寸优化等,并基于优化结果对床身结构进行改进设计。     

2CZ-21型甘蔗种植机机架的力学分析与优化

简述了基于3D实体单元的2CZ-21型甘蔗种植机机架设计有限元法。分析了甘蔗种植机机架在弯曲和扭转组合工况下的应力和应变分布。讨论了机架在危险工况下的强度和刚度问题，提出了修改意见并对原有结构进行了优化。对改进设计后机架结构进行了强度和刚度分析，并确立了合理的轻量化方案。     

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。