结构仿生化黄麻纤维摩擦材料性能研究

采用室温碱处理和热处理两种改性方法对黄麻纤维进行表面改性处理,以头发和羊毛纤维为原型,对黄麻纤维进行结构仿生,考察了仿生螺旋型黄麻纤维对摩擦材料摩擦性能的影响.结果表明:螺旋型黄麻纤维质量分数在3％,螺旋升角为66 °时材料的摩擦因数符合制动要求,并且耐磨性能最优.在100℃和150℃时,螺旋型黄麻纤维的加入增加了摩擦材料的摩擦因数;在200℃和250℃时,螺旋型黄麻纤维增强摩擦材料的摩擦因数随着纤维添加量的增加而减小,随着纤维螺旋升角的减小而略微减小,而平直型黄麻纤维增强摩擦材料的摩擦因数最高;在300℃和350℃时,螺旋型黄麻纤维摩擦材料表现出较好的耐磨性能,摩擦材料的摩擦因数随着螺旋型黄麻纤维螺旋升角的减小而减小.     

油茶果园施肥一体机挖穴过程仿真与试验

为开发出适合山地油茶果园挖穴施肥覆土的机具,且具有结构简洁、质量小、功耗小的特点,针对挖穴施肥的方式,采用离散元法建立了螺旋钻头挖穴过程的仿真模型;并结合三因素三水平正交试验和响应曲面分析方法,仿真分析了进给速度、钻头转速和钻头螺旋升角对挖穴作业功率消耗的影响规律。结果表明：试验因素对消耗功率的影响从小到大依次为钻头螺旋升角、进给速度、钻头速度,进给速度和钻头转速组合、钻头转速和钻头螺旋升角组合交互作用对消耗功率的影响显著。进行了参数优化,确定最优组合为：在进给速度0.03m/s条件下,钻头转速180r/min、钻头螺旋升角15°时最小功率消耗为1.134kW。田间试验表明：优化组效率效果明显优于对照组,优化后单个坑作业时间12.1s、百坑油耗1.08L。     

适配免耕播种单体的清秸装置改进设计与试验

地表秸秆覆盖免耕播种具有蓄水保墒、提高土壤肥力、改良土壤结构、控制土壤侵蚀、降低生产成本和提高作物产量等社会、生态和经济效益。针对现有同位仿形免耕播种单体在重度秸秆覆盖、高速作业条件下,清秸装置作业质量差、工作效率低问题,改进设计了一种具有秸秆轴向加速推送功能的清秸装置。阐明了清秸装置清理秸秆机理,完成了关键部件清秸轮和助推螺旋设计,确定了影响其工作性能主要参数及取值范围。采用二次回归正交旋转中心组合试验方法,以作业速度、工作偏角、螺旋升角、螺旋叶片数为试验因素,清秸率和工作阻力为性能评价指标,在构建的EDEM-ADAMS联合仿真试验平台上实施参数组合优化试验,结果表明：各因素对清秸率影响由大至小依次为作业速度、工作偏角、螺旋叶片数、螺旋升角;各因素对工作阻力影响由大至小依次为作业速度、工作偏角、螺旋叶片数、螺旋升角。应用Design-Expert软件对试验结果进行参数组合优化,当螺旋升角为40°、螺旋叶片数为4、作业速度为7.5～10.7 km/h、工作偏角为20.0°～32.5°时,清秸率大于85%,工作阻力小于110 N。在作业速度8、9、10 km/h条件下,对螺旋升角40°、...     

玉米脱粒机板齿螺旋角与脱粒特性的影响研究

以板齿式脱粒工艺及其对应仿生技术为基础及板齿式玉米脱粒装置的主脱粒轴板齿螺旋角为研究对象,分析了玉米脱粒机板齿螺旋角与脱粒特性的影响关系。同时,利用有限元分析软件ANSYS,分析板齿螺旋角与板齿最大应力之间的关系,得到板齿最大应力随板齿螺旋角的变化的趋势。分析结果表明,当板齿螺旋角在35°~40°之间时,板齿脱粒特性较好。该研究对进一步提高脱粒工艺的水平具有重要的现实意义。     

拖拉机动力输出双万向轴分析及优化设计

作为轮式拖拉机的重要动力输出机构,动力输出轴能够为各种类型的配套农机具提供动力。针对动力输出轴在旋耕作业中易断裂的问题,对传动系统中影响输出轴受载的因素进行研究。首先对万向节传动结构进行分析,构建万向节Ⅲ轴的工作摆角与动力输出轴的阻力扭矩之间的解析关系,并利用MATLAB进行仿真分析。然后基于TRIZ理论,以减小摆角为目标,应用物-场模型设计出一种新型的旋耕机机构,并利用ADAMS和EDEM进行新机构与原机构的对比仿真试验,结果表明摆角极值由8.42°减小至3.29°,平均值由5.23°减小至1.62°,阻力扭矩放大系数的平均值由0.55减小至0.36,有效地减少动力输出轴上的载荷,提高动力输出轴的使用寿命。该研究结果能够为同类问题提供解决思路和技术支持。     

螺旋槽轮式排肥器对肥料块破碎效果的仿真试验与研究

为解决排肥过程中因肥料结块导致排肥不均与堵塞的问题,本研究基于离散元方法建立肥料块Bonding模型,依照Box-Behnken试验设计原理,以转速、截面形状、螺旋升角为自变量,以排肥均匀度变异系数和肥料块粘结键断裂率为响应值,采用三因素三水平响应面分析方法,对各因素及其相互作用进行分析。仿真结果表明：3个因素对肥料块粘结键断裂率影响的主次顺序分别为螺旋升角、截面形状、槽轮转速;对排肥均匀度变异系数影响的主次顺序分别为槽轮转速、截面形状、螺旋升角;螺旋槽轮最佳工作参数组合为：槽轮转速为21r/min、截面形状为勺型、螺旋升角为70°,最佳工作参数组合下的肥料块粘结键断裂率为97.67%,排肥均匀度变异系数为8.56%。     

两段圆锥式螺旋扶蔗机构的设计与仿真分析

为了研究扶蔗机构的工作性能,优化扶蔗器结构参数设计,建立了运动学模型。使用Solid Works,设计两段圆锥式螺旋扶蔗机构虚拟样机,应用ADAMS仿真工具,进行了运动学及力学仿真试验及高速摄影试验验证。结果表明:输送段安装角为30°~60°范围内,甘蔗不跌落;输送段安装角为60°,甘蔗扶起到最高点为4.1s,效率最高;螺旋倾角为45°时,甘蔗均匀受到螺旋叶片的作用力,无跌落现象;螺距有效范围为270~290mm,螺距为285mm时,受力情况以及扶起变化最稳定,扶起效果最好。     

螺旋角对单螺杆泵泄漏影响的数值计算

为了探究不同泵结构参数对单螺杆泵泄漏的影响,以1/2型线全金属单螺杆泵为例构建几何模型,基于PumpLinx软件进行瞬态数值计算,并结合外特性试验验证其可靠性,对不同总螺旋角下单螺杆泵的流量变化规律及流场分布展开研究.研究结果表明:单位螺旋角恒定条件下,时均流量随着总螺旋角的增加、单位压差的减小而增大;瞬时流量极小值随着总螺旋角的增加而减小,极大值基本保持一致,接近理论流量17.9 m³/h.斜向泄漏缝隙两侧压力随定子转子啮合位置变化,特定位置压力差随着总螺旋角的增大而减小;特定啮合区监测点的瞬态泄漏流速极大值随着总螺旋角的增大而减小,其极大值最小为4.3 m/s.相关研究成果对于单螺杆泵的泄漏分析具有一定的借鉴意义与参考价值.     

搅拌滚筒内非牛顿流体的流场分析

针对混凝土这种典型的非牛顿流体中的宾汉流体,建立了其本构方程和流体力学模型.以有限元为依据,应用计算流体动力学技术,基于k-ε模型,利用Fluent软件计算了预拌混凝土在搅拌滚筒内的三维流场,数值模拟搅拌叶片螺旋角为73°时流场的流线和轴向出料速度,较为真实地反映了混凝土在滚筒内搅拌的实际情况.通过与搅拌叶片螺旋角为66°和80°的搅拌滚筒内流动的模拟计算比对,表明螺旋角为73°的叶片的搅拌性能和出料速度均优于其他螺旋角的搅拌叶片,能满足搅拌运输车的搅拌滚筒对拌料匀质、送料连续和低动力消耗的要求.同时进行了相应的试验比对,验证了模拟分析的正确性.该搅拌筒内非牛顿宾汉流体混凝土流动的数值模拟,表明基于k-ε模型的CFD数值模拟方法可以用于搅拌筒内混凝土这种非牛顿流体的搅拌过程的分析.     

钻头结构对烟苗移栽成穴质量影响的研究

为探究叶片式钻头结构对成穴质量的影响,以自行设计的叶片式钻头为研究对象,通过理论及试验的研究方法探究钻尖结构、螺旋升角、螺旋叶片高度和叶片旋向对钻头成穴质量的影响。结果表明:三角形钻尖与锥形钻尖钻头(E1、E2)在工作时的振动加速度分别为31.55、10.89m/s 2;螺旋叶片高度为80、100、120mm(E3、E4、E5)时,排土量分别为298.29、325.96、436.96g;正向与反向叶片钻头(E2、E3)排土量分别为154.43、298.29g,附土量分别为105.60、31.07g,振动加速度分别为10.89、9.96 m/s 2。在钻头结构为锥形钻尖、螺旋升角为60°、螺旋叶片高度为120mm、瓦片式叶片为反向时,成穴质量最佳。研究可为烟苗井窖式移栽叶片式成穴钻头的优化提供参考。     

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。