转速对磁吸滚筒式精密排种器工作精度的影响

通过分析种子在滚筒壁上的受力,在保证种子被吸附于滚筒壁上且不滑动的前提下,找出了所需的磁吸力与其所处位置的关系,并分析了滚筒允许转速与磁吸力的关系.分析结果表明,滚筒允许转速与种子质量、种子比磁化系数、种子质心处磁场力、滚筒半径及种子与滚筒壁摩擦系数等因素有关.最后,对油菜种子进行了穴盘播种试验,其结果表明:当磁吸头采用锥头形式、线圈电流强度为0.2A、匝数为2000、滚筒转速为15r/min时、排种器单播率达93.334%.     

木工适张带锯条的振动分析

应用振动理论,对经过适张处理后的木工带锯条进行研究,确定张紧力与系统固有频率之间的关系,提出将带锯条的振动简化为弦的振动与受拉伸的梁振动.用电测法测应变换算张紧力,用频谱分析法测量系统的固有频率,理论解得到试验支持,同时计算张紧力和张紧应力.     

真空堆载联合预压法在某工程中的应用分析

本文通过对某工程孔隙水压力及水平位移资料的观测，分析了通过真空一堆载联合预压法加固软上地基，土颗粒所受侧压力、渗流力、抗剪力的变化，揭示了真空一堆载联合预压法在地基水平位移方面的相互作用．以及地下水位的变化对其加固效果的影响。     

高校图书馆服务于农村劳动力教育培训研究

本文就高校图书馆教育培训优势,以及如何利用图书馆对农村劳动力教育培训进行研究,旨在为当前农村劳动力素质提高拓展新途径.     

曲杆梁格内力影响面的机动分析有限元法

以米勒-布雷斯劳原理为基础,运用小变形的叠加原理,将曲杆梁格机动分析与有限元静力分析相结合,建立了曲杆梁格内力影响面分析的机动分析有限元法,该方法把内力影响面分析归结为求解在一个等效结点荷载作用下的梁格位移场,并推导了计入横向剪切变形影响的十二自由度空间曲梁单元等效结点荷载计算公式.该方法概念简洁清晰,与静力法及直接求解位移的机动法相比,计算效率大为提高.算例表明了本文理论和所推导公式的正确性.     

焊接机器人三维防碰撞力传感器的设计

设计了一种三维防碰撞力传感器,其可利用一个输入实现x、y、z三个方向的碰撞力测试,用在6-D.O.F串联焊接机器人末端时,既可以实现对机器人本身的保护,也可以安装在其他设备的末端执行器上实现对设备的保护.     

锯链张力和松弛的分析

静止状态下锯链不垂离导板的临界张力与导板轮廓线圆半径和锯链质量线密度成正比．无缓冲器导板的锯链安装张力应比有缓冲器导板的大．锯链和链轮的制造误差可能引起锯链附加张力或松弛下垂．锯链的松弛程度可用趾部间隙来衡量．锯链与导板的热胀冷缩不同步可能引起热张力或热松弛．文章给出了各种张力和趾部间隙的计算公式．     

Cross-sectional cutting of bamboo with a pair of shearing blades for bamboo cube production

As a new use of bamboo, bamboo cubes may be useful as a shot-blast material for surface treatments. However, a suitable processing technique for bamboo cubes has not been established. In this study, to obtain basic knowledge regarding the processing technology for bamboo cubes, we installed shearing blades (upper and lower blades) in a universal testing machine to test cross-sectional shearing of bamboo. The shearing force generated in this shearing was composed of a vertical component (F _v), a forward component (F _f), and a side component (F _s). This shearing force (F _v, F _f, and F _s) and the machining accuracy were investigated under various processing conditions. The shearing force became larger as the thickness of bamboo increased. In particular, F _v showed a tendency to increase rapidly. Changes in the shear angle of the upper blade had a remarkable influence on F _v. This result suggests that the shearing force could be greatly decreased by adjusting the shear angle. The shearing force within bamboo of 3mm in thickness was almost unaffected by the blade angle, and the change of shearing force with increasing clearance was almost indiscernible. It was clearly demonstrated that a large number of bamboo cubes could be made when the shear angle was large and cross-sectional shearing was performed from the bark side. However, a consequence of a large shear angle is that burr area increases. Part of this article was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003     

桥面垫层混凝土破坏与补强技术

该文在旧桥改造维修中,对桥面垫层混凝土破坏机理及补强技术提出了一些看法和措施建议,可供工程实际应用参考。     

论节能式炉气体木材干燥室的设计

本文讨论了节能式炉气干燥室设计的一些技术问题，如提高自生风引力增强通风；多种传热方式并用，增强传热，降低热损失的途径等，以达到节能降耗、快速干燥的目的。