液态变量施肥机两种不同变量机构的研究

精细农业对于促进我国农业的飞速发展,具有极其深远的现实意义与历史意义.液态变量施肥机是实现精细农业作业的一种智能化农业机械,具有施肥方便、简捷、保护环境、减少污染、化肥利用率高等特点.为此,针对液态变量施肥机的关键执行部件-变量施肥机构,设计了两种不同结构的液态变量施肥机构.同时,阐述了两种机构系统的组成、原理及其工作过程,并对各自的结构特点进行了比较分析,其结果为加快液态变量施肥机的改进设计提供重要的参考.     

探针注入式深层施肥机构的运动分析

目前,我国化肥存在着施用不合理、利用率低及对环境污染严重等问题.为此,针对农业传统施用化肥存在的问题,设计了液态施肥机的探针注入式深层施肥机构,建立了探针的运动方程.作业试验表明,探针注入式深层施肥机构能够较好地深施液态肥料,可获得良好的液态肥料施用深度;液态施肥机满足了各种农艺要求,能够保证深施液态肥料的作业质量;探针注入式深层施肥机构设计合理,具有实用可行的特点.     

产纤维素酶真菌混合发酵研究进展

总结了常见的分解纤维素真菌种类,并介绍了纤维素酶生产的方法。传统的利用单一菌种发酵纤维素材料的方法存在降解率低,发酵时间长等缺陷。而利用微生态原理,使用多个菌种进行混合发酵的方法被证明可以有效降解纤维素。重点介绍了固态混合发酵和液体混合发酵的工艺,并对产纤维素酶真菌混合发酵的前景作了预测。     

穿心莲内酯超临界CO2重结晶工艺初探

采用单因素实验法探讨超临界CO₂重结晶压力、温度、时间对穿心莲内酯的纯度和结晶率的影响，并借助扫描电镜进行晶体形貌考察，利用高效液相色谱仪进行纯度检测。结果表明，采用超临界CO₂重结晶技术得到的穿心莲内酯晶体形貌更加细小，并呈絮状分布在结晶板上；选择较佳纯化工艺参数为重结晶压力14 MPa，温度55℃，时间60 min，CO₂流量20 L/min时，得到的穿心莲内酯纯度达90%以上，结晶率超过45%。     

基于MATLAB仿真的非规则齿轮行星系扎穴机构的优化设计

为更好地满足深施型液态施肥机喷肥针入土垂直度及穴口较小的农艺要求,采用MATLAB GUI开发平台,编写了非规则齿轮行星系扎穴机构的反求设计与运动学分析仿真软件。该软件避免了正求方法试凑参数的盲目性,通过改变静轨迹上若干型值点的坐标,控制喷肥针尖姿态,直观动态地显示出反求过程、结果以及机构仿真运动过程,优化出最佳参数:穴口宽度为28 mm,静轨迹的高度为252 mm、宽度为182 mm。为了验证扎穴轨迹的正确性进行高速摄像试验,观察和分析了实际作业过程中喷肥针尖的相对运动轨迹、关键点姿态。试验结果表明:喷肥针尖轨迹高度246 mm、宽度188 mm,在试验误差允许范围内,轨迹的高度和宽度与理论仿真软件优化结果基本一致,充分验证反求设计分析的准确性和可行性。该研究为扎穴机构的反求设计提供了参考。     

GNF56×2型单螺杆浓浆泵的研制

该文描述了GNF56×2型单螺杆浓浆泵的结构特点，结合非牛顿型流体的磨损机理提出了单螺杆浓浆泵的设计方法 、使用中应注意事项及措施，解决了单螺杆浓浆泵输送高粘度、含颗粒的非牛顿型流体时引起泵的严重磨损、性能下降及寿命短等问题，总结了泵的优点，该泵比普通型单螺杆泵性能优，可靠性好，具有广泛的使用前景。     

Herbicidal Potential and Quantification of Suspected Allelochemicals from Four Grass Crop Extracts

Unknown compounds in crop plants are inhibitory to seed germination and early seedling growth of weed plants. A Petri dish assay showed that barley (Hordeum vulgare L.), oats (Avena sativa L.), rice (Oryza sativa L.) and wheat (Triticum aestivum L.) extracts significantly reduced root growth of alfalfa (Medicago sativa L.), barnyard grass (Echinochloa crus‐galli, Beauv. var. oryzicola Ohwi.) and eclipta (Eclipta prostrata L.). As the concentration of crop extracts increased, root growth of the test plants were significantly reduced. A high‐performance liquid chromatography analysis with nine standard phenolic compounds showed that the concentrations and compositions of allelopathic compounds depend on the extracted plant extracts. Caffeic acid, hydro‐cinnamic acid, ferulic acid, m‐coumaric acid, p‐coumaric acid and coumarin were present in all the crop plant species, and hydro‐cinnamic acid were detected as the highest amount. Coumarin at 10^?3 m significantly inhibited root growth of alfalfa and barnyard grass more than that of eclipta. The research suggests that extracts of barley, oats, rice and wheat have an allelopathic effect on alfalfa, barnyard grass and eclipta and that the findings of bioassay were considerably correlated with the type and amount of causative allelochemicals, indicating that the allelopathic effects on three test plants were ranked in order of wheat (highest), barley, rice and oats (lowest). The results may have value in enabling weed control based on natural plant extracts or crop residues in the fields.     

Recent Development of Solid/Liquid Reaction Synthesis Technology for Metal Matrix Composites

TheSolid/liquidReactionSynthesisTechnologyforMetalMatrixCompositeshasattractedanincreasinginterest, andalotofimportantprogresseshavebeenmadeinrecentyears.Fivetypicalprocesses ,exothermicdispersion ,coatingtech nologybycontactreaction ,liquidcontactreaction ,meltinfiltrationandreactivespraydeposition ,havebeenreviewed .More attentionhasbeenpaidtorecentdevelopmentoftheresearchworkontheexothermicdispersion ,coatingtechnologybycontact reactionandliquidcontactreaction .Thecharacteristicsoftheseprocessesareanalysed ,andtheexistedproblemsonthereac tionsynthesistechnologiesarediscussed .     

灵芝深层液体发酵过程研究

研究灵芝液体菌种的培养时间对灵芝液体发酵的影响,以及菌丝量、胞外粗多糖量及pH值随发酵时间的变化,结果表明,培养6d的液体菌种最佳,发酵7d发酵液中的菌丝量最大,pH值最低。