Trunk muscle activation and low back loading in lifting in the absence of load knowledge

People who know the actual mass of an object to be lifted normally prepare themselves before attempting a lift to control the movement and to minimize low back loading. In this study, the trunk muscular reactions and low back torque were investigated in the situation in which the individual did not know the actual mass but only had some idea of the range within which the mass lay. Nine males lifted boxes weighing 6.5 or 16.5 kg under the condition in which they knew the actual mass before attempting a lift (the ‘known’ condition) and the condition in which they only had the information that the mass would be within the range of 6.5–16.5 kg (the ‘unknown’ condition). The ground reaction forces and body movements were measured in the trials and, from these, the L5/S1 torques were calculated. The activation of back and abdominal muscles was also measured. For the 6.5 kg weight, a higher (16%) back muscle activation in grasping the box and a higher (10%) peak L5/S1 torque in actual lifting were observed in the ‘unknown’ compared with the ‘known’ weight condition. For the 16.5 kg weight, the back muscle activation was lower (10%) during grasping, and higher (10%) during lifting in the ‘unknown’ compared with the ‘known’ weight condition. Knowledge of the load had no effect on the activation of the abdominal muscles. It was concluded that in the so-called ‘unknown’ conditions, the risks of low back injury were increased in comparison with the conditions where the actual weight was known in advance.     

Comparison study of the biorthogonal spline wavelet filtering for areal rough surfaces

Research into techniques for areal surface analysis has recently included wavelet filtering. The requirements for filtering surface analysis include: linear phase shift; finite pulse response and perfect reconstruction — only biorthogonal wavelets satisfy these conditions. The biorthogonal spline wavelet is considered for areal surface characterisation due to the curvature of the surfaces considered as examples. In this paper, the models and algorithms of biorthogonal B-spline and cubic spline wavelets are introduced. The lifting algorithm is used as a simple tool for design of spline wavelets. Bioengineering surfaces are used to test and compare the two kinds of wavelet filters to obtain the rough surfaces.     

永济蒲津渡口遗址保护工程水文地质条件及处理方案

永济蒲津渡口遗址保护工程位于黄河冲积河漫滩上，地下水十分丰富，径流条件好；在保持其原地、原貌、原位不变的情况下，如何处理建筑物的防水问题，将是很关键的。本文通过对里外抽水试验资料的综合分析，并运用裘布依完整井稳定流理论公式及泰斯完整井非稳定流理论等方法对场区含水层渗透能力进行了计算、评价，提出了较为合理的处理方案。     

基于Internet/Intranet的供应链管理系统的研究

文章在分析当前供应链管理系统现状的基础上，提出了一种基于Internet/Intranet的供应链管理策略，详细阐述系统的网络组建方案、数据集成方法和体系结构。以震雄机械作为实施对象将其划分为系统管理、客户服务管理、计划执行管理、动态联盟管理、技术支持与服务等五大模块。     

雪山工程-水力发电与跨流域调水综合工程

雪山工程位于澳大利亚东南部的墨累达令流域,是一项在墨累河和马兰比吉河上进行水力发电、农业灌溉调水和河道管理的综合工程。从工程管理、规划、主要设施建设、调水量、水权、用水分配原则以及一些环境问题的角度介绍雪山工程的情况。     

StratixII系列高性能FPGA及其配置方案

本文阐述了ALTERA公司新推出的StratixII系列高密度、高性能FPGA的体系构架、特点和性能,描述了该系列FPGA的配置方案。     

加热炉出入口管线振动的原因及对策

分析了催化柴油加氢精制装置反应进料加热炉出入口管线振动原因,并采取了相应的措施,使振动限制在允许的范围内,保证了装置的安全运行。     

三峡永久船闸金结安装研究

三峡双线五级船闸水头113m单级最高工作水头45．2m，闸室有效尺寸280m×34m×5m。共设人字门24扇，总重20000t，预计整体调试时间长达1年之久，安装时间将不足两年。影响工期的制约因素是门体吊装和运输，而决定安装质量的是门体焊接变形控制。第二闸首人字门安装是关健，有就地顶升法和浮式移位法。后者可使底坎混凝土浇筑时间缩短20天，移位操作时间缩短12天，停航时间缩短62天。     

液氧汽化器肋片结霜、结冰对理论换热面积的影响及解决方案

对星形管空温式强迫通风型汽化器进行了复算 ,指出肋片结冰、结霜是影响此类汽化器理论换热面积的主要因素 ,提出了三组汽化器切换使用、提高空气温度 (加热 )等解决措施