大型荧幕作业下工作绩效与视觉不适之研究

伴随今日荧幕技术进步,大型荧幕已经成为一种流行趋势.本研究希望得知大型荧幕对视觉、工作绩效之影响,并了解肌肉不适之情形.比较四种荧幕尺寸(15、17、19和21英时)以主观评量、工作绩效、视觉压力、颈肩姿势与肌肉活动之影响.由主观评量得知,19时工作绩效是最好的,荧幕大小对视觉表面积的影响是显著的,在工作超过一小时候,眨眼率与视觉疲劳也大幅增加,颈肩姿势对荧幕大小无显著的,最后,荧幕大小对平均作业时间有显著的影响.结论,19 英时萤幕是我们推荐适用于长时间的作业平台.     

Shoulder strength of females while sitting and standing as a function of hand location and force direction

This study evaluated single-handed isometric push strength capabilities of females working at or above-shoulder level. We examined the influence of force exertion direction (vertical, horizontal and lateral), angle of shoulder flexion from horizontal (0°, 30°, 60° and 90°) and gross body posture (standing and sitting), on maximal volitional shoulder strength. Force exertion direction had the greatest affect on shoulder strength (p < 0.0001). Strength was greatest in the vertical axis pushing downwards and weakest in the horizontal plane pushing forwards. Angle influenced shoulder strength when considered together with direction (p < 0.0001). However, these effects were dominated by direction results. Marginal differences in strength existed between sitting and standing (p > 0.05). These results can be used to design workspaces that consider individual strength limitations and their dependence on force direction, work orientation, and gross body posture.     

A review of: “Catastrophic Failures”. By V. BIGNELL,G. PETERS and C. PYM. (Milton Keynes: OPEN UNIVERSITY PRESS, 1977.) [Pp.274.] £5·50.

Cumulative trauma illness currently accounts for over half of all occupational illness in the United States. From 1987 to 1989 there was a 100% increase in the reported number of cases of cumulative trauma illness (Bureau of Labor Statistics 1990). Shoulder region pain ranks second only to low back and neck pain in clinical frequency, and the occurrence of occupational shoulder illness is on the rise. This paper summarizes findings of a subset of recent epidemiologic, laboratory, and field studies conducted in order to identify occupational risk factors for cumulative trauma disorders (CTDs) of the shoulder region. These studies have identified the following risk factors as being associated with particular shoulder pain syndromes: awkward or static postures, heavy work, direct load bearing, repetitive arm movements, working with hands above shoulder height, and lack of rest. The paper begins with a discussion of several shoulder disorders, includes problems in studying cumulative trauma, presents results of recent studies, and concludes with suggested ergonomic controls that could help to reduce the incidence of shoulder disorders, by eliminating or reducing exposure to the associated risk factors.     

翻领成型器曲面研究

研究了翻领成型器的交接曲线和曲面形成,给出了翻领成型器的肩曲面及其边界曲线的数学模型,指出左右对称的两肩曲面是两个顶点不同的锥面.此外,从几何角度提出了设计参数e的限制条件,为正确设计翻领成型器提供了依据.     

激光穴照并穴位贴敷联合康复训练治疗脑卒中后肩手综合征的疗效观察

目的:观察激光穴照并穴位贴敷联合康复训练对脑卒中后肩手综合征的疗效影响。方法:将108例脑卒中后肩手综合征患者随机分为观察组和对照组,各54例。对照组采取康复训练;观察组在康复训练的基础上配合激光穴照并穴位贴敷治疗,治疗时间为4周。在治疗前后分别对两组采用目测类比评分法(VAS)、Barthel(BI)指数、改良的Fulg-Meyer(FMA)法评定患侧上肢手指水肿、疼痛程度、关节活动范围、日常生活活动能力(ADL)及上肢运动功能,评定其临床疗效。结果:两组治疗后偏瘫侧水肿、肩痛、关节活动度、Barthel指数及FMA-Meyer评分较治疗前均有显著改善(P0.05),观察组明显好于对照组(P0.05),且观察组临床疗效总有效率(96.30%)显著优于对照组(74.07%),P0.05。结论:激光穴照并穴位贴敷联合康复训练对脑卒中后肩手综合征疗效显著。     

Manufacture of a mechanical test rig to simulate the movements of forces within the shoulder

The shoulder complex, also known as the glenohumeral joint is the most manoeuvrable and one of the most well used joints of the human body. Over time problems can occur with the glenohumeral joint and surrounding muscles, cartilage, tendons and ligaments caused by ageing or by over stressing the shoulder complex. This work examines the design of a new innovative glenohumeral test rig. The test rig was required to imitate the movement of the humerus in the human body and replicate all the ranges of motion, which it can move in when combined with the relevant bones, muscles, ligaments and tendons in the shoulder complex. A variable force also had to be applied to the glenoid in all ranges of motion. Research had to be undertaken in the ranges of motion of the shoulder complex and the forces acting on the glenoid. Concept designs were initially created to mimic specific ranges of motion; adduction, flexion, internal (medial) and external (lateral) rotation for example. The concepts were evolved and combined to develop a test rig that would replicate any axial movement of the shoulder. Research determined the most appropriate manufacturing processes and materials so that the test rig could be manufactured in the material laboratories.     

An examination of shoulder kinematics and kinetics when using a commercial trunk harness while sheep shearing

Sheep shearing is a very physically demanding occupation, especially on the low back, such that many commercial harnesses have been developed to help reduce the load on the back. Such harnesses have been shown to significantly reduce peak and cumulative low back loads; however, the effect that these harnesses have on the shoulders, which are also highly involved during sheep shearing, has not been previously examined. The purpose of this study was to examine the shoulder postures and cumulative shoulder moments of 12 New Zealand sheep shearers. The use of the trunk harness reduced the percentage of time spent in shoulder flexion greater than 90 degrees and the time spent in shoulder abduction greater than 45 degrees as well as reduced the cumulative net joint flexor, abductor, and adductor shoulder moments by a minimum of 21%, 14%, and 42%, respectively. Therefore, the use of a commercial trunk harness to reduce low back injury may also help to reduce the risk of shoulder injury while sheep shearing.     

The relationship between shoulder torques and the perception of muscular effort in loaded reaches

The objective of this study was to define the quantitative relationship between external dynamic shoulder torques and calibrated perceived muscular effort levels for load delivery tasks, for application in job analyses. Subjects performed a series of loaded reaches and, following each exertion, rated their perceived shoulder muscular effort. Motion and task physical requirements data were processed with a biomechanical upper extremity model to calculate external dynamic shoulder torques. Calculated torque values were then statistically compared to reported calibrated perceived muscular effort scores. Individual subject torque profiles were significantly positively correlated with perceived effort scores (r² = 0.45–0.77), with good population agreement (r² = 0.50). The accuracy of the general regression model improved (r² = 0.72) with inclusion of factors specific to task geometry and individual subjects. This suggests two major conclusions: 1) that the perception of muscular shoulder effort integrates several factors and this interplay should be considered when evaluating tasks for their impact on the shoulder region; 2) the torque/perception relationship may be usefully leveraged in job design and analysis.     

Subjective and objective evaluation of shoulder muscle fatigue

In order to relate EMG signs of localized muscle fatigue to subjectively perceived muscle fatigue, a study was undertaken on 20 healthy volunteers exposing their right trapezius muscle by raising the arm to 90° of abduction. Every person performed two contractions: 0 kg hand load during 5 min and 2 kg hand load during 2.5 min. Surface EMG was recorded and analysed with respect to RMS amplitude and mean power frequency (MPF). Subjective muscle fatigue was estimated with a psychophysical rating scale (Borg's CR-10 Scale). At high load level we found a significant correlation between MPF and the CR-scores (r = ? 0.46), but at low load level there was no correlation. At high load level there was a linear decrease of MPF with increasing load dose, but at low load level the MPF did not change, despite significant subjective fatigue. There was a linear rise of the CR-score with increasing load dose, more pronounced at high load level. It was concluded, that at low load levels common in working life, MPF and subjective scores seem to provide different fatigue information. Moreover, the MPF did not seem to work as a valid estimator of muscle fatigue at this low load level. Caution is recommended if it is to be used in static low-load situations.     

Muscle fatigue during intermittent isokinetic shoulder abduction: Age effects and utility of electromyographic measures

Most existing evidence regarding the effects of age on muscular fatigue has focused on prolonged isometric contractions, repeated maximum dynamic contractions and individuals beyond traditional retirement age (>65 years). In the present study, age-related differences in muscle fatigue during submaximal dynamic efforts were examined. There were 24 younger (18–25 years) and 24 older (55–65 years) participants, all of whom were healthy and active, with equal numbers of each gender within each age group. Participants performed repetitive, intermittent shoulder abductions until exhaustion, at peak moments of 30% and 40% of individual maximum voluntary isokinetic contraction (MVIC) and with cycle durations of 20 and 40 s. Fatigue development was determined based on changes in MVIC, electromyographic (EMG) signals and ratings of perceived discomfort (RPD). Following the exhaustive exercises, strength recovery was monitored using a series of MVICs over a 15-min period. Results indicated the existence of an age-related fatigue resistance, with the older group demonstrating significantly slower rates of MVIC decline and RPD increase and smaller modifications in EMG-based fatigue measures. These age effects were generally more pronounced at the higher effort level. Main effects of effort level and cycle duration were also significant, while gender effects appeared to be marginal. Rates of strength recovery were not significantly influenced by age. In addition, the utility of standard EMG-based fatigue measures was assessed. Findings indicated that time-dependent changes in static and dynamic EMG-based measures were roughly comparable in terms of sensitivity and variability, supporting the use of standard EMG analyses for fatigue monitoring during intermittent dynamic contractions.