基于有限元的盘式制动器耦合场研究

盘式摩擦制动器在汽车上有着广泛的应用。但该制动器在制动过程中因制动器温度的急剧上升,将使制动性能降低,甚至有可能导致制动器失效,因此制动器温度和应力分布对制动器的寿命及制动性能有着重大影响。本文采用有限元方法对制动器的耦合场进行了分析研究,耦合分析结果表明:在制动开始阶段,制动器迅速升温,高温区集中在制动器摩擦面表层,最高温度达195℃;制动过程结束后,整个制动器有一段较长时间的降温过程;制动器的最大热应力-时间曲线变化规律不一致,但均满足材料强度要求。     

冻烤鳗抗生素残留量微生物分析法

本文叙述了农业部1997年批准的中华人民共和国冻烤鳗水产行业标准中以纸片扩散法检测烤鳗样品中抗生素残留量的原理,操作方法,最低检出量和对30份烤鳗样品的检验结果。同时探讨了制定烤鳗抗生素残留量的质量标准和检测方法的思路。     

A nonlinear 3D finite element analysis of the soil forces acting on a disk plow

This study aimed to compare predicted soil forces on a disk plow with measured forces within the tillage depth of clay (90 g kg⁻¹ sand, 210 g kg⁻¹ silt, 700 g kg⁻¹ clay) and sandy loam (770 g kg⁻¹ sand, 40 g kg⁻¹ silt, 190 g kg⁻¹ clay) soils. The model assumed the effects of both tilt angle and plowing speed. Two plowing speeds (4 and 10 km/h) at three tilt angles (15°, 20° and 25°) were compared and the draft, vertical, and side forces determined. A 3D nonlinear finite element model was used to predict the soil forces while a dynamometer was used to measure them on a disk plow in the field. An incremental method was used to deal with material nonlinearity and the Trapezoidal rule method was used to analyze the dynamic response of soil during tillage. Field tillage experiments were conducted to verify the results of the finite element model. It was found that increasing the tilt angle of the plow increased the draft and vertical forces and decreased the side force. Increasing plowing speed increased the draft and side forces and decreased the vertical force. Generally, the results from the finite element model were found to be compatible with the experimental results in clay soil, while in sandy loam the differences between predicted and measured data were probably due to problems of measuring soil mechanical characteristics in the triaxial test.     

圆盘分割法在转基因大豆抗虫鉴定上的应用

大豆食心虫是大豆的主要害虫之一,随着大豆种植面积的扩大,其为害逐年加重。应用转基因抗虫品种防治大豆食心虫是现阶段应用研究热点,但其抗虫性一直存在着不易检测的困难。针对这一问题,本实验室设计、提出一种新型室内抗虫生测方法———圆盘分割法。该方法是根据大豆食心虫发生规律和取食习性来进行转基因大豆抗虫鉴定。试验证明了圆盘分割法的可行性;同时,该方法结合网室接虫鉴定法可以使转基因大豆抗虫鉴定更为高效和准确。     

Cotton management in a compacted subsurface microirrigated coastal plain soil of the southeastern US

A loamy sand Acrisol (Aquic Hapludult) that had been microirrigated for 6 years became so severely compacted that it had root limiting values of soil cone index in the Ap horizon and a genetic hardpan below it. Deep and surface tillage systems were evaluated for their ability to alleviate compaction. Deep tillage included subsoiling or none. Both deep tillage treatments were also surface tilled by disking, chiseling, or not tilling. Subsoiling was located in row or between rows to avoid microirrigation tubes (laterals) that were buried under every other mid row or every row. Cotton (Gossypium hirsutum) was planted in 0.96-m wide rows. Cotton yield was improved by irrigation from 485 to 1022 kg ha⁻¹ because both 2001 and 2002 were dry years. Tillage loosened the soil by an average of 0.5–1.3 MPa; but compacted zones remained outside tilled areas. Subsoiling improved yield by 131 kg ha⁻¹ when performed in row where laterals were placed in the mid rows; but subsoiling did not improve yield when it was performed in mid rows. For subsurface irrigation management in these soils, the treatment with laterals buried under every other mid row was able to accommodate in-row subsoiling which improved yield; and this treatment was just as productive as and had been shown to be less expensive to install than burying laterals under every row.     

iSCSI虚拟服务器盘阵在图书馆终端机群中的应用

分析了安庆师范学院图书馆的硬、软件资源,并提出了运用iSCSI技术将普通服务器虚拟成SCSI服务器,运用Software RAID方法将普通硬盘组建成磁盘阵列,在客户服务终端机上调用虚拟SCSI服务器RAID盘阵上的服务程序,从而模拟其在真实SCSI盘阵上的高效运行和存储效果,以提高服务器、终端机群以及维护人员的工作效率,降低维护成本。     

驱动式圆盘犁机组平衡分析

对与手扶拖拉机配套的驱动式圆盘犁研究过程中有关机组受力及机组平衡作了分析探讨,确定了机组的合理工作挡位及机组重心位置,提出了减小机组偏转的方法。研究结果可供与手扶拖拉机配套的驱动式圆盘犁产品设计及推广使用部门参考。     

Evaluation of infiltration measurements under olive trees in Córdoba

Field experiments were conducted at the Alameda del Obispo Experiment Station of the Andalusian Autonomous Government, Córdoba, Spain, to compare the field-saturated hydraulic conductivity (K_fs) measured by four different techniques: constant-head well permeameter (CP), falling-head lined borehole permeameter (FP), twin-rings (TR) and disk infiltrometer (DI). For each technique, measurements under and outside the olive-canopy were compared in order to detect differences in K_fs. All techniques gave higher K_fs values under the canopy, but significantly higher only for FP and TR. Outside the canopy K_fs values obtained with CP and TR were significantly higher than those obtained with the FP and the DI methods, but the FP and the DI as well as the CP and the TR K_fs values were statistically the same. Under the canopy, K_fs values obtained with the TR method were significantly higher than those obtained with the other three techniques. Estimates of K_fs, however, are most comparable for DI and FP.     

不同造粒方式下复合肥颗粒特性的比较

研究圆盘造粒和挤出-滚圆造粒2种方式制取复合肥造粒的工艺过程及其颗粒特性。比较这2种造粒工艺过程及颗粒特性差异性,用于优化颗粒成型方式,提高颗粒成粒率、改善颗粒外形、颗粒力学特性等,以便对复合肥颗粒有更深入的了解。结果表明:从测定颗粒特性的各项指标中可以看出,挤出-滚圆造粒由于有挤出和滚圆2个过程,所制作的复合肥颗粒致密度较高,稳定性好,圆度和流动性较好,粒径分布也比较均匀;圆盘造粒所制肥料颗粒粒度分布广,干燥速率高,肥料养分释放速度快。     

圆盘摩擦泵在轴封中的应用

针对电站水轮发电机组主轴支承轴瓦的润滑油密封系统出现严重漏油故障问题，研究了产生故障的原因，结合理论分析计算，提出了将开式泵壳改为闭式泵壳，使之成为圆盘摩擦泵。从广义上讲，实现了由“灌”到“排”的转变，使泵壳缝隙原本的泄漏流动变为吸油流动。实践证明采取的措施得当，水轮机主轴密封漏油问题得以圆满解决。