箍筋增强型胶合竹柱抗压试验

竹片经过胶合形成的竹柱构件,克服了竹材形状各异的缺点,使之能够运用到各种建筑和桥梁结构之中,但由于竹片之间黏合的原因,竹柱构件受压破坏时常出现竹片层间劈裂.为改善胶合竹柱的受力性能,笔者提出箍筋增强型胶合竹柱设想,并对其进行了静力试验;结果证明箍筋改善了竹柱的工作性能,提高了竹柱的极限承载能力.     

齿轮热处理常见问题与对策

随着我国机械工业的飞速发展,对其重要组成部分——齿轮的质量要求也越来越高。文章就对齿轮在热处理过程中常见的问题与对策进行一下分析。     

土柱试验中充填介质对纵向弥散系数的影响研究简

通过室内一维土柱淋滤试验，选择NaCl为示踪剂，研究示踪剂在不同介质中的穿透行为，探讨不同介质由于自身特性对纵向弥散系数的影响。结果表明，土壤黏粒的增多会引起弥散系数的降低，由细砂的2×10-3cm2／s降低到掺土样品的3×10-4～4×10-4cm2／s左右，且弥散系数会随着容重的减小而减小，由1．25×10-2cm2／s减小为3．87×10-4cm-2／s。另外，有机质含量也会影响柱内有机污染物的弥散，表现为有机质舍量高的柱内弥散稍大于有机质含量低时柱内的弥散。     

高效水冷离心机管模撒粉装置结构改进

文章主要介绍了在水冷金属型离心铸造中,必须向金属型（管模）内加入硅钡粉,又称管模粉,其粒度为0-0.1mm,含钡的质量分数在4%-12%左右,舍钙得质量分数为1%,有些厂家用1%的铝替代钙,其加入量一般按管模的内表面积、浇注管子重量来确定。管模粉在管模内起到瞬时强化孕育作用,同时管模粉对消除铸管表面的气孔和针孔起决定性作用。为保证管模粉加入量的均匀性及连续性,并满足高效生产率的要求,对DN300mm以下小口径管其管模粉输送装置结构及重要部件进行了配套改进设计。     

端曲面齿轮-连杆复合机构的特性分析与应用

为研究异形齿轮及其与其他机构复合之后的运动特性,以典型异形齿轮—端曲面齿轮副为例进行研究,根据其相交轴间变传动比的特点结合连杆机构,提出了一种可同时实现预期运动轨迹和运动速度的运动形式,端曲面齿轮—连杆复合运动机构。建立了复合运动机构的传动坐标系,以坐标变换为基础推导了复合机构运动方程,通过矩阵实验软件(matrixlaboratory,MATLAB)分析了复合运动机构的位移、速度和加速度的影响因子及其变化规律。并基于复合机构的传动特性,设计了一种饲草压捆机捆压机构;采用Solidworks和机械系统动力学自动分析(automatic dynamic analysis of mechanical systems,ADAMS)进行仿真加工,构建了该机构的仿真模型并进行运动仿真分析,同时加工了齿轮副部分进行试验,将试验结果与MATLAB的理论结果、ADAMS的仿真结果对比,得到的位移误差为0、速度误差为3.4%、加速度误差为3.6%,验证了理论分析的正确性,该研究在齿轮机构与连杆机构的复合运动、机构简化方面具有指导意义。     

一种新型农用高扬程大流量活齿齿轮转子泵的流量特性研究

针对农业排灌机械的要求和特点，提出并分析了一种可广泛应用于农业生产的压力输送泵——活齿齿轮转子泵的结构形式及工作原理，分析了径向间隙自动补偿的实现方式，推导出了平均流量和瞬时流量公式，研究了该泵的流量特性。结果表明该泵具有流量大、流量脉动小、工作轮齿间无啮合力、运行平稳、噪声低、机械效率高及径向间隙可以自动补偿等诸多优点。在一定条件下，该泵可作为高扬程大流量农用水泵或两相流的压力输送泵，具有广阔的应用前景。     

Time‐resolved in‐situ pH measurement in differently treated,saturated and unsaturated soils

The pH‐value is of utmost relevance for soil properties and functioning. Hence, a time‐resolved in‐situ measurement is mandatory but lacking. As an alternative, a two‐probe pH electrode with gel‐covered reference electrode was newly constructed and tested for a continuous, in‐situ pH recording in saturated and unsaturated soil. This was done using samples from a set of 14 soils with different composition and pH$ _{\rm CaCl_2} $ ranging from 3.5 to 7.5 in batch and repacked soil column experiments. In the latter, changes in pH and redox potential were monitored upon transport of citrate‐phosphate buffer and pig slurry through the soil columns. The pH measurements were largely stable even upon substantial shifts in soil moisture content down to air‐dry conditions. The results of the pH measurements agreed with standard methods using settled soil suspensions in electrolyte solutions and the conventional combination (single‐probe) pH electrode. Testing the suspension effect, it was found that measuring pH directly in the soil is recommended. The pH measured in‐situ was closest to pH values determined in 0.01 M CaCl₂ suspensions according to DIN ISO 10390 (DIN, 2005 ). The transport of citrate buffer and pig slurry as pH active substances through soil induced strong effects on the pH and in part on the redox potential; the reversible effects lasted over days, which may affect the mobility and speciation of nutrients and pollutants as well as microbial processes.     

农用汽车后桥传动的优化设计

由于农用汽车使用区域的特殊性（多行驶在农村道路上或在农田院所作业等），对农用汽车后桥传动的要求比较严格。为此，以后桥传动的体积最小为目标函数，采用随机方向法寻求优化值，再用3线性插值法进行一维搜索求得最优值，进行优化设计。     

混联式HEV发动机输出转矩实时测算方法

针对混联式混合动力电动汽车( HEV)发动机输出转矩估计存在误差,进而导致HEV能量控制策略无法得以准确实现的问题,以行星齿轮混联式HEV为研究对象,分析了动力耦合机构的参数,并应用行星齿轮传动动力学模型及效率模型,推导得出了行星齿轮混联式HEV发动机输出转矩的估计算法.理论计算及实车测试结果表明,模型计算值与实车测试值之间的最大相对误差由5％ ～8％减小为3.94％.     

Numerical Method for Load Bearing Capacity of High Strength Steel Columns at Elevated Temperature

In order to make fire resistance design of high strength steel columns in building structures, the numerical calculation method on load bearing capacity of high strength steel columns at elevated temperature was investigated. By taking the mechanical property of high strength steel at elevated temperature into consideration, extension was made on the inverse calculation segment length method and the program to compute the load bearing capacity of high strength steel columns at elevated temperature was performed. The program was adopted to compute the load bearing capacity. The results obtained by the program and the finite element analysis were compared and good agreement had been found. The influence of magnitude, distribution mode of residual stress and initial geometry imperfection on ultimate load bearing capacity was analyzed by employing the program. It is shown that the extended method can be is shown used to calculate the load bearing capacity of high strength steel columns at elevated temperature; the magnitude and distribution mode of residual stress had little influence but the geometry imperfection have significant influence on ultimate load bearing capacity.