The vibration characteristics of chain saws and their influence on vibration white finger disease

The vibration from chain saws can cause vibration-induced white finger disease (VWFD). Measurements of vibration levels on the front and rear handles of different chain saw-types, and on the operator's middle finger were collected at three logging camps on Vancouver Island. Factors effecting the vibration levels on the finger and handles were investigated. The acceleration at the firing frequency was found to be the dominant factor effecting handle and finger vibration. Other factors which were investigated were: grip force; the presence of handle covers; and chain sharpening procedure. Weighted acceleration levels are calculated and this information is used to assess the latency period for fallers to develop VWF disease.     

Induction motors bearing fault detection using pattern recognition techniques

This paper proposes a systematic procedure based on a pattern recognition technique for fault diagnosis of induction motors bearings through the artificial neural networks (ANNs). In this method, the use of time domain features as a proper alternative to frequency features is proposed to improve diagnosis ability. The features are obtained from direct processing of the signal segments using very simple calculation. Three different cases including, healthy, inner race defect and outer race defect are investigated using the proposed algorithm. The ANNs are trained with a subset of the experimental data for known machine conditions. Once the network is trained, efficiency of the proposed method is evaluated using the remaining set of data. The obtained results indicate that using time domain features can be effective in accurate diagnosis of various motor bearing faults with high precision and low computational burden.     

基于虚拟仪器的动车组转向架测试系统的设计

基于虚拟仪器技术,开发了动车组轮对轴承齿轮箱以及牵引电机的测试系统。系统通过传感器检测轴承齿轮箱以及牵引电机的振动信号,对振动信号进行各种谱分析,对于动车走行部早期的损伤进行诊断,并对数据进行保存。     

The effect of vibration on the skeleton, joints and muscles. A review of the literature

Owing to the elasticity and plasticity of the skeleton, joints and muscles, the musculoskeletal system is capable of absorbing and damping mechanical vibration without damage as long as the vibration level is within tolerable limits. However, technical developments have led to the exposure of many people to intolerable variation levels with destructive changes as a result.

These injuries to the musculoskeletal system continue to be the subject of research interest. Initially, the joints and joint complaints attracted the greatest attention. Vibration damping takes place mainly in the joints. The incidence of destructive joint changes has been examined in comprehensive clinical, epidemiological and radiographic studies, mainly concentrating on the joints of the hand and arm. The response of muscles to vibration is often expressed in the form of a tonic vibration reflex (TVR) which arises as a result of stimulation of the muscle spindles and therefore resembles the classic tonic stretch reflex. There is increased muscular activation for stabilisation of the joint positions, especially during whole-body vibration. Studies have also disclosed how vibration affects body equilibrium and equilibrium control and how vibration can elicit muscle pain, cramps and reduced muscular strength.     

5L型压缩机管路振动分析与减振措施

对于5L型往复式无油润滑压缩机提高转速后管路振动这一故障,通过振动理论分析和压缩机动力计算、复杂管道系统气流脉动计算,得出振动不是由机构动不平衡或基础设计不当所引起,而是由气柱固有频率与激发主频率基本重合和气体压力不均匀度超过允许值所引起。采取了加装孔板和缓冲器综合运用的减振措施,基本上消除了压缩机组及管路的振动。     

A new approach on vibration analysis of locally nonlinear stiffness and damping system

The nonlinear force induced by spring and damping of 2-degree-of-freedom locally nonlinear vibrating system is regarded as applied force, and its mathematical model is established in this paper. Then impulse response temporal method of linear vibrating system is applied in the system, the response of locally nonlinear vibrating system is obtained by convolution integration between unit impulse response of corresponding linear system and equivalent nonlinear force, and numerical simulation of the model is attained. Finally, the feasibility of the new method on the domain of locally nonlinear vibrating system is verified by comparing the results, which supplies a new method to solve approximately vibration response of locally nonlinear vibrating systems.     

制约空压机长周期运行的因素及处理措施

通过对引进C150MX3型空压机近几年来的运行和故障情况的分析，得出制约空压机长周期运行的3个因素：冷却器结垢、扩压器腐蚀和二级振动值高。分析了引起故障的原因，并采取了相应措施，实现空压机长周期稳定运行。     

一种超低频电动水平振动台的模型及非线性分析

针对 一种超低频电动水平振动台实际的机电一体化结构，分析了其工作原理，给出了其数学模型，文中特别讨论了振动台的非线性因素，包括磁场的非线性，功率放大器输出的非线性以及动圈反应等方面。这些因素导致了谐波分量的引入，致使波形严重失真，就此提出了减少超低频电动水平振动台的非线性因素的方法。     

长距离小间距隧道爆破开挖设计与施工

某新建隧道位于两条既有平行隧道中间,隧道走向与既有隧道平行,净间距为5m,路线全长1098m,为全程小间距隧道,施工难度较大。本文通过现场试验和测试,参考岩石破坏的最大峰值速度,确定了快速施工的开挖方案和爆破参数,并通过该工程对爆破分级提出了一些建议。     

CSP热连轧机振动性质的确定

针对某钢厂CSP热连轧机出现的振动问题,综合运用现场实测和计算机仿真的方法对轧机振动的性质进行了系统的分析,并得到了如下初步结论:工作辊水平方向的振动是由主传动系统的扭转振动引起的强迫振动。