热喷焊Ni基Al2O3复合涂层在农业机械中的应用

农业机械中磨损件消耗量一直很大,造成了巨大的经济损失。因此,根据农业机械中农机具的实际工况,采用粉末火焰喷焊工艺,将Al2O3与Ni基自熔性合金粉混合后制备出金属-陶瓷系复合涂层,用MLS-23型湿砂橡胶轮式试验机对复合涂层进行了耐磨性试验,并比较和分析了不同Al2O3加入量的耐磨性。结果表明,在Al2O3的含量适当时,能大大地提高涂层的耐磨性,比单一涂层提高3倍以上,用此工艺处理常见耕作机械具(如犁铧、犁壁、耙片、旋耕刀片等)对提高其使用寿命具有重要的经济意义。     

表面改性粉末冶金件耐磨性影响因素分析

用纳米Al2O3与铁粉相混合作为铁基粉末冶金件的表面改性材料，通过激光熔覆试验对冶金件进行表面改性。运用优化设计法。在MM-200摩擦磨损试验机进行摩擦磨损试验，纳米Al2O3与铁粉涂层激光熔覆后，粉末冶金件表面耐磨性显著提高，得出影响耐磨性因素的回归方程。方程表明：纳米Al2O3的质量分数与载荷都是影响耐磨性的显著因素，且载荷的影响较纳米Al2O3质量分数显著。磨损量对比曲线显示，当纳米Al2O3质量分数为4％、8％时，随载荷增大磨损量趋于一致。     

绿色制造涂层刀具制备及切削性能分析与探究

随着机械工业绿色制造和高效切削等要求的提出,刀具切削性能的提高日渐紧迫,特别是孔加工时刀具磨损大、切削温度高、散热条件差、切屑排除困难、加工精度低等.基于此,采用磁控溅射镀膜技术在硬质合金刀具表面上沉积TiAlN涂层,分析和探究TiAlN涂层刀具在绿色制造过程中的切削性能、刀具磨损等相关内容.     

WC含量对合金陶瓷金属性能的影响

采用高频感应熔覆工艺制备不同WC含量的Ni基合金涂层,研究分析WC的晶粒度及其分布对合金涂层金属性能的影响。结果表明:高频感应熔覆工艺可以制备出组织结构均匀、组织缺陷少,硬质相完整的合金涂层;合金涂层中存在WC硬质相的晶粒聚焦现象,未熔化的WC颗粒与镍基合金形成固溶体提高了涂层的组织性能,增加了涂层硬度。     

硬质合金涂层刀具车削Ti6Al4V磨损实验研究

使用两种涂层硬质合金刀具在云南机床厂生产的CY6140普通卧式车床上对Ti6Al4V钛合金棒料进行干切削,当达到一定的切削长度时,使用工业显微镜观察、测量并记录了刀具前后刀面的磨损形貌及磨损量的值.一旦达到刀具磨钝标准时就停止切削.通过分析刀具的磨损形貌以及两种涂层刀具磨损的曲线图可知,在切削Ti6Al4V材料时,SP...     

轴向超声振动车削GH4169合金的试验研究

为研究切削速度和进给量对镍基合金GH4169切削时的影响,利用有无轴向超声振动对镍基合金GH4169切削时的切削力、切削温度、表面粗糙度和刀具磨损进行车削试验。结果表明:超声振动能够减缓切屑锯齿化程度;超声振动切削力远低于普通车削,当速度增大时2种加工方式下切削力逐渐靠近;进给量与切削温度、粗糙度和切削力呈正相关;切削速度的增大使得切削温度和表面粗糙度也不断升高,且超声振动切削温度和表面粗糙度显著较低。     

高速车削铁基高温合金硬质合金刀具磨损机理

使用4种硬质合金涂层和非涂层刀具材料进行铁基高温合金GH2132的高速干车削试验,采用电子扫描显微镜(SEM)观察刀具的磨损形貌,通过能谱分析(EDS)分析磨损表面的元素分布,并对刀具的主要磨损机理进行分析.研究结果表明,使用硬质合金刀具材料高速干车削铁基高温合金GH2132时,刀具的磨损机理主要为粘结磨损、扩散磨损、氧化磨损并伴有少量的微崩刃.高速切削时刀具的前刀面磨损形态不同于常速切削时的磨损形态,即磨损不表现为月牙洼的形式,而是表现为切削刃处磨损最大的斜面磨损形式,前刀面磨损区域随切削速度提高而减小,但磨损深度增大.     

纳米SiC颗粒增强Ni基激光熔覆涂层高温抗氧化性能的研究

文章研究了通过添加适量纳米SiC颗粒,采用NiCoCrAlY合金粉末在GH4037合金表面激光熔覆制备了纳米SiC颗粒增强Ni基合金涂层,对熔覆层及界面区进行了显微组织分析,进行了1070℃下的高温抗氧化性试验及结果发表。     

几种难加工材料的可加工性分析及其刀具材料的选择

本文对一些难加工材料如 :不锈钢、高锰钢、高温合金、钛合金、高硅铝合金、镍基合金、环氧树脂、石材等的可切削加工性进行了分析 ,并提出了合适的切削加工刀具材料 ,对实际生产具有指导意义     

农村降氟改水的研究

对几种不同絮凝剂的降氟改水效果进行了比较研究.实验研究发现,利用Al2(SO4)3·18H2O,PAC,Al(Cl)3·6H2O,WS-F与MR等絮凝剂,可将水中氟化物含量降低至我国生活饮用水卫生标准以下.尤其是WS-F与MR在投加量和温度影响等方面都明显优于其他3种絮凝剂,可较好地解决高氟地区的饮水问题.     

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。