Three-dimensional spinal motion and risk of low back injury during sheep shearing

Sheep shearers are known to work in sustained flexed postures and have a high prevalence of low back pain (LBP). As sustained posture and spinal movement asymmetry under substantial loads are known risk factors for back injury our aim was to describe the 3D spinal movement of shearers while working. We hypothesised that thoraco-lumbar and lumbo-sacral movement would be tri-axial, asymmetric, and task specific. Sufficient retro-reflective markers were placed on the trunk of 12 shearers to define thoraco-lumbar and lumbo-sacral 3D motion during three tasks. Thoraco-lumbar movement consistently involved flexion, left lateral flexion, and right rotation. Lumbo-sacral movement consistently involved right lateral flexion in flexion with minimal rotation. Shearers therefore work in sustained spinal flexion where concurrent, asymmetric spinal movements into both lateral flexion and rotation occur. These asymmetric movements combined with repetitive loading may be risk factors leading to the high incidence of LBP in this occupational group.     

Segmentation of microscope images of living cells

This paper describes a segmentation method combining a texture based technique with a contour based method. The technique is designed to enable the study of cell behaviour over time by segmenting brightfield microscope image sequences. The technique was tested on artificial images, based on images of living cells and on real sequences acquired from microscope observations of neutrophils and lymphocytes as well as on a sequence of MRI images. The results of the segmentation are compared with the results of the watershed and snake segmentation methods. The results show that the method is both effective and practical.

Assistant force compensation for hand movement of patients by using exogenous signals and/or neurophysiological signals

Because functional diseases of the brain can cause disabilities related to human movement control, a compensation method was developed for improving the performance of hand movements. The compensation for human hand movements can be carried out by adding an assistant force that is generated from artificial equipment attached to a human arm. From the experiment on visual target tracking, it was found that the tracking trajectory was adequately represented by a dynamic model of the motion of an articulated industrial robot arm, and the different abilities for movement control among healthy people and patients were classified by different model parameters as position loop gain, velocity loop gain, and response delay. Dynamic force compensation was approached by considering the different control features of the patients. The effectiveness of the proposed compensation method was verified in a simulation study on an actual industrial robot arm. A human-machine interface, e.g., a brain-computer interface (BCI), for realizing the control of artificial equipment to compensate for human hand movements is also presented and discussed.     

Current techniques for measuring motion

The sports scientist and the ergonomist, although sharing a common disciplinary background, pursue fundamentally different goals. The patterns of approach to the analysis of movement they adopt are, nevertheless, similar and a model of this approach is presented. Some potential sources of error associated with each stage of the process are identified.

In measuring motion in sport, cinematography has played a dominant role. The method has obvious advantages; but analysing film is a slow, pedestrian task, and subject to human error. Where an investigator is experienced and understands his problem clearly he can often achieve his aims with a limited number of measurement variables. This may also meanhe can adopt automatic and specific techniques of acquiring information. Such methods include alternative photographic techniques, but also involve the specialised transducers and automatic analysers that are now burgeoning in the field. Some of these techniques are discussed.     

无人车运动稳定性的模糊神经网络PID控制

受转向或侧向风影响,无人驾驶车在运行的过程中易产生失稳.采用了模糊神经网络PID算法,将系统输出偏差的变化量,经模糊化后输入到神经网络PID控制器中,对车辆的质心侧偏角、横摆角速度进行调整,达到控制车辆平稳运行的目的.在不同的工况下对算法的有效性进行了试验分析.结果表明,该算法使系统响应超调减少,反应时间加快,具有较强的抗干扰性.     

系列变螺距螺杆的设计计算

为了使罐头包装机具有柔性加工的功能并提高设备利用率,根据圆柱形罐的螺杆供送机构的原理,设计开发了可调变螺距螺杆供送机构和对应不同罐径的系列变螺距螺杆。根据对罐的运动规律要求,给出了变螺距螺杆结构参数的设计计算方法以及罐的运动规律的计算分析方法。阐明了罐运动规律与螺杆长度、罐直径、螺距、螺距数之间的关系。研究的变螺距螺杆的设计计算及运动规律分析方法适合常用的罐径系列。     

高层建筑竖井内烟气流动特性及控制方法

竖井火灾烟气流动特性和控制是与高层建筑火灾安全紧密相关的问题。从竖井烟气流动作用因素、烟气参数分布特性与烟气上升速度3个方面论述了对于高层建筑竖井烟气流动特性的研究现状。总结了目前常用的竖井烟气控制方法及工程实践中存在的问题,提出了改善烟气控制效果的方法和思路。     

土壤初始含水量对注射灌土壤水分运移分布 特性影响试验研究

通过室内不同土壤初始含水量的注射灌水分入渗试验,研究了土壤初始含水量对注射灌土壤水分运移分布特性影响。研究表明：注射灌的累积入渗量与时间呈幂函数关系,土壤初始含水量越大,相同入渗时间的累积入渗量越大。在出水口下方土壤水分湿润范围较大,土壤含水量也较大,而在出水口上方则相反。土壤初始含水量越大,土壤湿润范围越大,距离出水口相同距离的土壤含水量越大。以上研究可为进一步补充注射灌理论技术提供基础。     

A comparative study of three different kinds of school furniture

Abstract

Several studies indicate that the ISO standards for school furniture seem to be inappropriate, and there is increasing evidence that the inclination of the seat should be forward and that it should be possible to adjust the table-top to a certain non-horizontal angle. However, these studies have predominantly used objective measurement methods on adult subjects for short-term experiments in rather artificial surroundings. By means of structured interviews registering the school children's perception of ergonomic comfort, the present study has compared three types of school furniture—the original ISO-standard type, and two different new types characterized by forward slanting seats and tiltable desk-tops, the main difference between the two being approximately 15 cm in the height of the chair as well as the table. The study showed that the highest of the two tilting types was perceived to be significantly better than the two others in terms of table height, chair height, reading position, back-rest, and global assessment. Likewise, the feature of a tiltable table-top was considered overwhelmingly positive independently of the height of the furniture. It is recommended that school authorities, producers of school furniture, and relevant medical personnel consider these results for alternative designs of school furniture. It should be kept in mind, however, that school furniture is only one among many factors in the multifactorial field of the back health of school children.     

大型室内游乐场人员疏散运动时间的模拟

针对大型室内游乐场人员疏散运动时间的问题,分析了游乐场人员构成、人员步速和肩宽及其分布与人员疏散运动时间的关系,采用Pathfinder模拟了该运动时间与其影响因素间的关系.模拟结果表明:对于特定的大型室内游乐场,在外界环境和人员密度不变的条件下,人员疏散运动时间随人员步速的增大而减少,随人员肩宽的增大而增大,随儿童比例的增大而增大;人员步速和肩宽均服从常值分布时的疏散运动时间最短,服从均匀分布时的疏散运动时间最长,服从正态分布时的疏散运动时间介于二者之间.