黄河万家寨水利枢纽大坝安全监测系统改进完善方案

万家寨水利枢纽工程为黄河中游第一级控制性枢纽工程,及时准确地监测枢纽大坝的位移变化,不仅关系大坝本身的安危,对下游河道和两岸安全、晋蒙电网的安全稳定运行都有重要意义。根据万家寨水利枢纽大坝安全监测系统现有观测设施、设备的运行情况及实测资料,经过分析和现场试验,提出了万家寨监测系统存在的不足及改进完善方案。     

斐济南德瑞瓦图水电站配水环管保温保压浇筑

在高水头机组中蜗壳和配水环管保压浇筑混凝土施工技术目前已广泛应用,但同时采取保温浇筑的却很少。文章介绍了斐济项目配水环管保温保压浇筑混凝土的方案及施工过程数据,经论证,保温保压浇筑有利于水电站的长期安全可靠运行。     

彭家岩水电站压力管道滑坡治理技术

对彭家岩水电站压力管道滑坡治理工程进行了分析总结。实践证明,根据彭家岩水电站工程地质条件和滑坡机理分析,所采取的完善排水、外封内排,卸荷减载、稳定坡脚,下挡上护、灌桩支撑的工程治理技术措施是有效的,通过综合治理保障了电站的安全可靠运行。     

Acoustic evaluation and adjustment of an open-plan office through architectural design and noise control

Arranging office space into a single open room offers advantages in terms of easy exchange of information and interaction among coworkers, but reduces privacy and acoustic comfort. Thus, the purpose of this work was to evaluate the acoustic quality of a real open-plan office and to propose changes in the room to improve the acoustic conditioning of this office. The computational model of the office under study was calibrated based on RT and STI measurements. Predictions were made of the RT and STI, which generated the radius of distraction r(D), and the rate of spatial decay of sound pressure levels per distance doubling DL(2) in the real conditions of the office and after modifications of the room. The insertion of dividers between work stations and an increase in the ceiling's sound absorption improved the acoustic conditions in the office under study.     

Factors affecting ambulatory heart rate in industrial workers†

The influence of several factors on the heart-rate (HR) response to tasks performed during regular work has been evaluated in a study population of 1654 male factory employees in Israel. Each worker was monitored for approximately one hour with an ambulatory electrocardiogram. The percentage change from resting HR decreased with increasing age and, as expected, was lower in sedentary workers than in manual workers. A highly significant negative correlation between the HR response and both systolic and diastolic blood pressure was found in the manual workers only. In further multiple regression analysis, after controlling for age, relative weight, smoking status, resting HR and the presence of abnormalities on the resting ECG, the association persisted for systolic BP only. Among young workers, both smoking and relative body weight were significantly associated with a higher HR response to work. Those with ECG abnormalities had lower HR response than those with normal ECGs, but not significantly so. These findings indicate that for roughly equivalent tasks and levels of resting HR, the HR response to regular work is influenced by several constitutional and behavioural factors. It may therefore be important to consider these factors when assigning workers to tasks involving strenuous effort.     

A study of hand grip pressure distribution and EMG of finger flexor muscles under dynamic loads

A matrix of miniature and flexible pressure sensors is proposed to measure the grip pressure distribution (GPD) at the hand-handle interface of a vibrating handle. The GPD was acquired under static and dynamic loads for various levels of grip forces and magnitudes of vibration at different discrete frequencies in the 20–1000 Hz range. The EMG of finger flexor muscles was acquired using the silver-silver chloride surface electrodes under different static and dynamic loads. The measured data was analysed to study the influence of grip force, and magnitude and frequency characteristics of handle vibration on: (i) the local concentration of forces at the hand-handle interface; and (ii) the electrical activity of the finger flexor muscles. The results of the study revealed high interface pressure near the tips of index and middle fingers, and base of the thumb under static grip conditions. This concentration of high pressure shifted towards the middle of the fingers under dynamic loads, irrespective of the grip force, excitation frequency, and acceleration levels. The electrical activity of the finger flexor muscles increased considerably with the grip force under static as well as dynamic loads. The electrical activity under dynamic loads was observed to be 1·5–6·0 times higher than that under the static loads.     

Basic study on the measuring of fatigue by the minimum audible pressure

Abstract

Nowadays, human senses of vision and hearing receive many stimulations. In particular, VDT work is commonly performed by people of all ages. Therefore, in order to regulate working hours we need to measure the fatigue due to VDT work. The current measuring system depends on the flicker value (CFF). This report describes a new measuring system which depends on the measurement of the fluctuation in the minimum audible pressure (MAP) while using the increase of threshold value as an index of fatigue, and the results of the related experiment. In Test I, the test sound was set at the pure sound of 1000Hz. In Test 2, an ordinary hearing acuity inspection room was used, using the method of limit measurement and headphones (Telephonies, TDH39, MX41/AR). As a result, it was verified that the most suitable rate of increasing and decreasing audible pressure was by 2 dB or 1 dB.

It was proved from these tests that the minimum audible pressure could be used satisfactorily as a practical index for absolute measurement of hearing sense fatigue.     

A Review of :“Leu Accidents du Travail.” By JACQUES LEPLAT et XAVIER CUNY. (Paris: Presses Universities de France, 1974.( [Pp.128. £0·00.

Police officers spend large amounts of time performing duties within a police cruiser and report a high prevalence of musculoskeletal problems. This study evaluated the effects of driver seat and duty belt design on posture, pressure and discomfort. Ten male and 10 female university students attended two sessions involving simulated driving in a standard police seat (CV) and an active lumbar support (ALS) seat. Participants wore a full duty belt (FDB) or reduced duty belt (RDB) in each seat. Lumbar postures, driver-seat and driver-duty belt pressures and perceived discomfort were measured. Gender × Seat interactions were found for pelvic (p = 0.0001) and lumbar postures (p = 0.003). Females had more lumbar flexion than males and were more extended in the ALS seat (?9.8 ± 11.3°) than CV seat (?19.8 ± 9.6°). The FDB had greater seat pressure than the RDB (p < 0.0001), which corresponded to increased pelvis discomfort. This study supports the use of an ALS seat and RDB to reduce injury risk associated with prolonged sitting in police officers.

Practitioner Summary: Police officers report a high prevalence of musculoskeletal problems to the lower back, associated with prolonged driving and further investigation is needed to reduce injury risk. This simulated driving study investigated seat and duty belt configuration on biomechanical measures and discomfort. Seat design had the greatest impact, regardless of gender and males benefited more from a reduced belt configuration.     

Ergonomics modelling and evaluation of automobile seat comfort

Automobile seats are developed in an iterative manner because subjective feedback, which is usually of questionable quality, drives the design. The time and cost associated with iteration could be justified if the process was guaranteed to produce a comfortable seat. Unfortunately, this is not the case. Current practices are based on the premise that seat system design teams need objective, measurable laboratory standards, which can be linked to subjective perceptions of comfort. Only in this way can predictions be made regarding whether or not a particular design will be viewed by the consumer as comfortable. This type of forecasting ability would effectively improve the efficiency with which automobile seats are designed. In this context, the research reported, developed, and validated a stepwise, multiple linear regression model relating seat interface pressure characteristics, occupant anthropometry, occupant demographics, and perceptions of seat appearance to an overall, subjective comfort index derived from a survey with proven levels of reliability and validity. The model performance statistics were: adjusted r ²?=?0.668, standard error of estimate?=?2.308, F (6, 38)?=?15.728, p?=?0.000, and cross-validated r (15)?=?0.952, p?=?0.000. From the model, human criteria for seat interface pressure measures were established. These findings could not have been attained without first demonstrating that (1) the data collection protocol for seat interface pressure measurement was repeatable and (2) seat interface pressure measurements can be used to distinguish between seats.