FEM on Coupled Hydromechanical Dynamic Response of Geogrid Reinforced Soil Retaining Wall

Geogrid reinforced soil retaining wall(GRSRW) is composed of panel,geogrid and soil,its coupled hydromechanical structural characteristics are increasingly emphasized in practice.In this paper,based on the characteristics of the reinforcement-soil interaction,the grogrid and soil around it with a definite thickness were regarded as a kind of composite material with strain-compatible condition.A saturated porous media model was introduced to simulate the soil and reinforcement-soil composite material hereby and the mathematic model for numerical analysis on structural characteristics of GRSRW was built up.The FEM equations were deduced from the standard Galerkin procedure,resolving these equations,we can gain the relevant dynamic response of saturated GRSRW.     

R4102直喷式柴油机起动过程粗暴性的测试分析

利用自行开发的数据采集系统，同步测量了Ｒ４１０２直喷式柴油机起动过程的瞬时转速及１、３缸的气缸压力，对起动过程粗暴性问题进行了测试分析，并研究了其对发动机连杆，活塞，活塞销等主要受力零件强度的影响，结果表明：该影响很大，设计中应予以考虑。     

曲轴圆角应力的影响因素

利用有限元分析的方法,详细讨论了单缸柴油机曲轴的曲柄形状对曲轴最危险截面应力的影响,通过多种设计方案的计算比较,使曲柄圆角处的应力峰值下降11.25%。其中,一种设计方案已用于S1115X120单缸柴油机,并在大批生产中得到验证,证明该方案是行之有效的。     

Irrigation scheduling in a mature peach orchard using tensiometers and dendrometers

Three trickle irrigation schedules, two of which were scheduled according to soil water potential ( soil) (tensiometer method) and daily stem contraction (DSC) (dendrometer method) respectively and the other one was a schedule of restricted water supply, were applied to a mature peach orchard.The annual water application based on soil was greater than that based on DSC. However, tree growth, fruit size and leaf water potential (leaf) on the trees in the dendrometer scheduling plot did not differ from those in the tensiometer scheduling plot while the premature fruit drop and fruit bud initiation were greatly different. The restricted water supply treatment limited significantly both tree and fruit growth. In addition, the lower leaf was observed on the trees in this plot.Further study shows that use of the dendrometer method for scheduling irrigation satisfies the water needs of the plant and that the tensiometer method is less accurate.Abbreviations leaf leaf water potential - soil soil water potential - DSC daily stem contraction - LVDT linear variable displacement transducer - PET potential evapotranspiration     

土壤水分特征曲线几种标定的对比分析

土壤水分特征曲线的标定是土壤水的能量和数量关系在不同尺度间转换的方法,也是植被生态需水机理研究的重要组成部分。通过对传统的迭代法、一次法和建立的2种混合遗传算法进行比较,标定的结果表明,多项式遗传算法能综合考虑2种方差的影响,并能给出一致性的标定结果,这种经验式混合遗传算法对传统的标定算法进行了改进。     

咸水灌溉下土壤水盐变化的试验研究

2002年在内蒙古河套灌区红卫节水示范园进行了咸水灌溉试验,分析试验结果得出:咸水灌溉下的土壤经过秋浇后含盐量可以降到咸水灌溉前水平。以荷兰Wageningen农业大学等单位开发的土壤水分大气作物系统模拟软件SWAP为工具,应用示范园的土壤、水、盐分试验资料对模型的参数进行了率定和验证,模型模拟结果和田间试验结果符合较好。     

新疆盐碱地长期利用盐水灌溉土壤盐分变化

在地下水位3～5m、壤质土壤条件下,利用盐碱地时用2～5g/L盐化水灌溉,土壤1m剖面均为脱盐状况。灌溉盐化水15年后,1m土壤残留阴离子浓度较小,多点平均为3.709毫克当量/100克土。其中HCO-3相对较多,1m多点平均为0.404毫克当量/100克土。K++Na+浓度很大,1m多点平均为2.492毫克当量/100克土。这时,土壤1m全盐多点平均为0.248%,在灌溉水矿化度不直接危害作物生长时,不影响耕作和作物正常生长。由此可见,盐化水在盐碱地上无排灌溉,是可行的。     

降低直喷式柴油机HC排放的试验研究

针对自然吸气直喷式柴油机，试验研究了喷油嘴压力室容积、喷油压力、喷孔直径、喷孔锥角、喷油提前角和空燃比等对ＨＣ排放的影响。试验结果表明，减少喷油嘴压力室容积，提高喷油压力，减小喷孔直径，适当加大喷孔锥我和小负荷时喷油提前角域可大幅度降低柴油机ＨＣ排放。     

小型柴油机活塞与活塞环匹配的研究

活塞与活塞环是柴油机中工作强度最大的组件之一,对柴油机的性能、使用寿命和工作可靠性等指标都有极大影响。通过BH160F小型柴油机活塞材料的选用及对压缩高度、火力岸布置、活塞顶部形状和活塞环匹配等方面进行改进设计,使柴油机获得了良好性能指标。     

SL4105柴油机的连杆杆身的变形分析

对SL4105柴油机的连杆进行了精确的三维建模,并考虑到连杆锻造毛坯和加工误差对连杆刚度的影响,根据实际情况对连杆运动时的整体变形进行了计算分析。分析结果表明:连杆的锻造加工误差会使连杆在最大爆发压力下产生较大的弯曲变形,变形最大值的大小和位置因加工误差的不同而不同。