正交实验分析孔加工中表面粗糙度的影响因素分析

文章采用镍合金钻削实验的相关数据进行了正交实验,分析研究钻削进给量和切削速度对孔的表面粗糙度的影响,同时通过极差和方差分析,研究进给量、切削速度以及他们的交互作用对孔的表面粗糙度影响的显著性。分析实验结果:在实际生产过程中,由于刀具材质以及机床自身的因素限制,需要选择很小的进给量和中等切削速度,既可以保证生产加工效率,也可以获得较高的表面加工质量。     

BTA单齿深孔钻具静力学分析

本文分析了BTA钻具的力学特性,通过UG建立了单齿深孔钻实体模型。利用ANSYS对BTA深孔钻进行了静力学分析,并对45钢棒料进行钻削实验,得出刀具磨损位置,为进一步研究刀具的磨损理论奠定理论基础。     

高速小孔钻削的振动分析

为了反映小深孔钻削机床加工过程中枪钻的振动情况,对不同枪钻进给量影响的系统进行研究。基于机床颤振的非线性理论、速度型切削颤振理论建立枪钻加工小深孔的动力学模型,从而得到枪钻系统的动力学方程。用MATLAB软件对动力学方程进行求解,得到在不同进给下的X,Y方向的振动偏移。分析结果表明,钻削加工中枪钻系统进给量影响工件的振动幅度。将其结果运用到实践当中,取得了极好的加工效果。     

7050-T7451铝合金钻削加工参数优化

钻削是孔结构最常见的加工方法，而铝合金钻削加工中产生的黏屑现象会加剧刀具磨损，降低加工质量，多用于工程机械、农业机械等。基于ABAQUS建立了7050-T7451铝合金钻削三维有限元模型，并且通过实验验证了有限元模型的准确性；结合有限元法和实验法，分析了主轴转速n、进给速度f和麻花钻顶角φ对轴钻削力和切削温度影响显著，认为7050-T7451铝合金合理的钻削参数为n=9000 r/min，f=425 mm/min，麻花钻顶角φ=118°。研究结果为铝合金结构件钻削参数优化和刀具几何角度的选择提供帮助，对提高钻孔质量具有重要意义。     

基于Deform-3D的不锈钢微孔钻削仿真分析

文章针对微孔加工微钻易折断的问题,分析了在316L不锈钢上钻削φ0.08mm的微孔时刀具折断的主要因素,采用Deform-3D模拟微孔钻削过程,对不同切削参数下的钻削力进行了回归分析,得到了钻削力的经验公式,并对其进行了显著性与精度分析,为优选微孔钻削工艺参数提供了有价值的参考依据。     

振动钻削提高Al2O3f+Cf/ZL109的机械加工性能

用挤压铸造法制备了Al2O3f＋Cf／ZL109混杂复合材料,并进行了振动钻削实验。结果表明,在合适的振幅和振动频率及钻削参数下,振动钻削可以提高Al2O3f＋Cf／ZL109混杂复合材料的机械加工性能,在较佳振幅20μm及振动频率60Hz条件下,振动钻削可降低钻头磨损量25%以上;随着混杂纤维含量的增加,刀具磨损增加,而其较佳的振幅和振动频率基本不变。     

铸铁钻削加工分析研究

现代机械制造中,铸铁材料应用广泛,机械设备中的发动机壳体、汽车的底盘、机床的底座等设备都充分利用了铸铁材料的优越性。为了满足底座与设备间的连接作用,底座的装配面进行钻削加工,钻削加工是常见的机械加工方式,为了提高劳动生产率,保证加工质量,降低劳动强度,文章主要分析铸铁材料的钻削加工特点,刀具工艺参数和夹紧力计算,为铸铁材料的钻削加工提供科学依据。     

铸铁钻削加工分析研究

现代机械制造中,铸铁材料应用广泛,机械设备中的发动机壳体、汽车的底盘、机床的底座等设备都充分利用了铸铁材料的优越性。为了满足底座与设备间的连接作用,底座的装配面进行钻削加工,钻削加工是常见的机械加工方式,为了提高劳动生产率,保证加工质量,降低劳动强度,文章主要分析铸铁材料的钻削加工特点,刀具工艺参数和夹紧力计算,为铸铁材料的钻削加工提供科学依据。     

电磁式轴向深孔振动钻削装置的设计

本文对电磁式轴向振动工作原理进行了分析,并设计了一种电磁振动钻削装置。在深孔加工过程中,通过调节交流电的大小与频率来控制振动切削装置钻杆振幅与频率,与负压抽屑装置配合使用,有效地改善深孔加工过程中断屑、排屑的问题,提高了深孔加工的质量。     

BTA单齿深孔钻具模态分析

减缓刀具损坏是切削领域和深孔加工领域的重要研究课题。本文利用ANSYS软件对单齿BTA深孔钻的三维模型进行模态分析,得出十阶振型云图,为单齿BTA深孔钻的钻具参数和深孔加工的切削参数的进一步优化提供了依据。     

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。