斜置旋耕三维凸埂研究

斜置旋耕时,由于刀辊的斜置,土垡受到旋耕刀的侧向撕裂而形成一楔状土台,所以应将旋耕沟底不平度的研究扩展到三维空间。本文详细分析了斜置旋耕作业过程中沟底凸埂的成因,建立数学模型确定了斜置旋耕凸埂的立体形状。理论研究和实测结果均表明：斜置旋耕沟底较正置旋耕沟底更为平整。     

斜置旋耕试验研究

在自行研制的斜置旋耕试验台上 ,分别采用国标旋耕刀和斜置旋耕刀进行了斜置旋耕试验 ,得到了水平分力、垂直分力、轴向分力、比功耗等参数随台车前进速度、刀辊转速和斜置角变化的规律     

斜置旋耕刀侧切刃曲线的理论研究

在对斜置旋耕动力学分析的基础上，推导出斜置旋耕刀侧切刃动态滑动条件，给出了侧切刃动态滑切角的定义和计算公式，以及计算实例。对比了国际耕刀正置和斜置时的动、静态滑动切角。把斜置旋耕刀的动态滑切角与侧切刃曲线统一于黎卡提（Riccati)微分方程中。该方程对斜置旋耕刀的计算机辅助设计有重要意义。     

基于FEM-SPH耦合算法的土壤切削仿真研究

建立了旋耕刀和土壤的FEM-SPH耦合仿真模型,基于FEM-SPH耦合算法,采用MAT147土壤材料和国家标准Ⅲ型旋耕刀,结合LS-DYNA971求解器,对土壤切削仿真进行了研究。对旋耕刀切削土壤的耕作过程进行了数值仿真模拟分析,得到了切削力和切土能耗随时间的变化曲线;计算出旋耕刀单刀切土扭矩为8.75N·m,与试验结果接近。通过正交试验分析,耕作深度为主导因子,对切土功率影响较大,调整耕作深度可有效降低土壤切削的功耗,提高耕作效率。研究表明:FEM-SPH耦合算法可有效应用于土壤切削仿真,可为研究土壤的破碎机理和耕作器具的优化设计提供理论依据。     

斜置旋转耕耘机三维仿真研究

利用基于对象理论的斜置旋耕机械工作过程三维仿真系统，研究了牵引速度、刀滚转速、斜置角和相位角等参数对斜置旋耕过程的影响，对单刀、单列旋耕刀、位于同一螺旋线上旋耕刀和整个刀滚的切土进行了仿真，在此基础上，探讨了斜置旋耕的基本工作机理，提出了斜置旋耕的基本约束关系。     

耕作部件对带状旋耕耕作质量的影响研究

应绿色可持续农业的发展要求，带状免耕播种技术在我国南方稻麦种植区得到推广与应用。为简明耕作部件对带状旋耕耕作质量的影响，在280、380和510 r/min刀轴转速下对凿型旋耕刀、直刃旋耕刀和IT225型旋耕刀进行田间耕作试验。试验结果表明，影响耕作质量的主要因素是耕作部件形状和刀轴转速。在刀轴转速为510 r/min时，IT225型旋耕刀创造的土壤回填率只有7%，土壤回填效果明显低于具有较小正切刃的直刃旋耕刀和凿型旋耕刀。凿型旋耕刀能够创造出较好的回填和土壤破碎的效果，但由于其没有侧切刃无法创造出整齐的种床截面。在刀轴转速为180 r/min时，凿型旋耕刀造成的种床截面扰动率高达20%。直刃旋耕刀能够形成齐整的种床截面和高于50%的土壤回填率，但产生的土壤破碎体粒径过大，不能满足播种的需求。本研究为带状旋耕耕作部件优化指明方向，即兼顾直刃旋耕刀和凿型旋耕刀的特点，将两种或几种刀具进行有机结合，以满足不同土壤条件下带状旋耕播种的需求。     

带状旋耕式小麦免耕播种机耕作部件作业机理研究

为明确带状旋耕式免耕播种机耕作过程中耕作机具与土壤间的相互作用机理,利用离散元仿真软件从微观层面对典型的且已广泛应用的IT225型旋耕刀、直刃旋耕刀和凿型旋耕刀进行仿真,研究发现旋耕刀具的抛土特性是影响土壤回填效果的关键因素。田间试验表明,土壤破碎体的回填率随刀轴转速的增加而下降。IT225型旋耕刀在高刀轴转速(280 r/min)下侧向抛土现象最为明显,在超高刀轴转速(510 r/min)时创造的土壤侧抛率最高,达到了92%,因此产生回填效果最差,回填率仅为8%,无法满足播种时种—土接触的需要。凿型旋耕刀耕作过程中可以勾带起部分土壤破碎体向机具前进方向抛洒,在刀轴转速为510 r/min时土壤侧抛率为85%,能够产生接近36%的土壤回填效果。直刃旋耕刀的侧向抛土集中在刀轴两侧10 cm范围内,在刀轴转速为510 r/min时侧抛率只有70%,回填率高达60%显著高于其他两种刀具。鉴于土壤回填效果对种—土接触的重要性,直刃旋耕刀耕作过程中具有土壤扰动范围小、土壤破碎体侧抛率低、回填效果好等优点,本文推荐直刃旋耕刀作为带状旋耕播种机的耕作部件。     

基于Solidworks旋耕刀实体建模与有限元分析

以国标旋耕刀、斜置旋耕刀和IT245旋耕刀3种基本刀型为基础,运用AutoLISP 编程获得每个刀型的阿基米德螺线,导入 Solidworks 软件进行实体建模,运用 Simulation 插件对其进行了有限元分析。分析结果表明：旋耕刀与刀辊联接处是刀具的一个重要的结构设计要点,在制造加工与设计中应尽力避免或减少应力集中;同时,对国标刀与斜置旋耕刀的有限元分析结果进行对比,发现后者在强度方面优于前者。     

基于离散单元法的旋耕刀耕作仿真分析

为分析旋耕刀耕作过程中所受阻力及其变化规律,实现对旋耕刀的数字化与可视化研究。利用离散单元法,对旋耕刀作业过程进行了仿真分析,本研究可为有效揭示土壤耕作机理提供理论依据。     

斜置旋耕机刀辊动平衡仿真试验分析——基于PRO/E和ADAMS

斜置旋耕机的刀辊在耕作时,由于刀盘安装的不对称和安装误差,会引起很大的动不平衡力矩,导致轴两端的轴承经常容易坏,机器不能正常工作。为此,利用参数化建模软件PRO/E和动力学仿真软件MSC.AD-AMS,对不同相位角的斜置旋耕机刀辊进行了不同转速下的仿真试验对比分析。试验结果表明,转速和旋耕刀安装相位角的不同,对到刀辊的径向动不平衡量影响比较大;刀辊的轴向动不平衡量很小,说明刀辊在工作时几乎没有轴向扭动。     

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。     

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。     

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.