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.. | Volume 3 Number 3-4, 1997

Volume 3 Number 3-4 1997



Torque Production Using Handwheels of Different Size During a Simulated Valve Operation Task
Lawrence J. H. Schulze, David Goldstein, Anupam Patel, Edward Stanton, James Woods, 109-118

Opening and closing valves in industrial facilities often requires operators to use bars and wrenches as levers (cheaters) in order to overcome initial actuation forces. In order to determine more appropriate operational specifications, the maximum torque production capability was measured when 12 male participants used four different valve handwheels at 3 different heights and 2 different angles (in relationship to the coronal plane). The results indicate that the participants produced significantly greater torque when the largest of the four wheels (40.6 cm diameter) was used than when the medium (22.9 cm), small (20.3 cm), and handled (17.8 cm) handwheels were used. Although the main effect of heights was found to be statistically significant, post-hoc analyses between the heights found them to be, essentially, equal. In addition, the vertical and horizontal wheel orientations were not found to be different. The results are applicable to all industries where handwheels are used and applicable to valve manufacturers for designing operational torque specifications below the values found in this study.

Differences in Eye and Hand Movements of Novice and Experienced Press Operators
Kyung Soo Park, Yu Chang Kim, 119-128

Presses are very widely used in industrial and commercial companies and are often the source of serious accidents occurring during operation. Most of the accidents are due to inadequate training of novice operators. Continuous recordings of eye and hand movements of five novice operators and five experienced operators in press operation were made. Significant difference between novice and experienced operators was observed in eye fixation time, eye movement patterns, hand dwell time, and eye-hand coordination. Also, differences were observed in spatial distribution of eye fixations during the die-closing portion of a stroke. There were no significant differences between novice and experienced operators in the eye and the hand movement time. The results could be used as basic data to establish a guide determining the method and training period to train novice operators.

"Hypersensitivity to Electricity" in the Office; Symptoms and Improvement
Anna-Christina Blomkvist, 129-140

Nineteen persons "hypersensitive" to electricity and 20 nonafflicted persons were studied for 1˝ years. The most discernible hypersensitivity symptoms were pricking sensations and redness in the face, but these symptoms were present in only half of the afflicted. Other symptoms were similar to symptoms experienced during office work and this study does not support the idea that electrosensitivity is one single syndrome. The "hypersensitive" persons improved significantly, mainly on neuropsychiatric symptoms, but the skin problems sustained-as did the belief about their cause. The afflicted persons used less conventional medication than the group of the nonafflicted, which suggests a general tendency for attribution to environmental factors.

Investigation of Blended Fibre Filtering Materials
Izabella Krucińska, Sławomir Zakrzewski, Irena Kowalczyk, Jadwiga Wiśniewska-Konecka, 141-149

Five variants of mixtures of different synthetic fibres at different area ratios were manufactured into needled nonwovens intended to be used as a filtering material for respiratory protection. Two variants were produced according to an earlier patent, and the contents of the other three was completely new. Samples of the nonwovens were tested for sodium chloride particles penetration and for breathing resistance. The results showed that one variant of a nonwoven, designated PP/PPFM, had very valuable filtering properties and that those properties were stable in time.

Amalgam in Dentistry. A Health Hazard for Dental Personnel?
Emma-Christin Lönnroth, Houshang Shahnavaz, 151-160

In a cross sectional study done in 1993 among dental personnel in Norrbotten, self-reported prevalence of muscular pain, headache, tremor, insomnia, irritation, impaired memory, and depression, as well as information regarding different mercury exposures were collected. Mercury exposures were determined as "number of amalgam fillings in teeth", "years in practice", "insufficient ventilation at work", "total number of amalgam removed, produced and polished per day", and "working in dental clinics." As controls, physicians and nurses from the same geographical area were selected. The correlation between symptoms and different mercury exposures was calculated using logistic regression. The results suggested a higher prevalence of muscular fatigue and tremor for female dental personnel compared to controls. Controls reported a lower prevalence of symptoms with increasing number of amalgam fillings in teeth. There was no correlation between the number of amalgam fillings handled per day and symptoms for dental personnel. Male dental personnel associated muscular fatigue, headache, impaired memory, and depression with increased handling of amalgam in the clinic, whereas the female dental personnel associate the same symptoms with the number of amalgam fillings in teeth. The strongest correlation was found between symptoms and insufficient ventilation at dental clinics for dental personnel.

Adaptation to a New Workplace According to Reactivity and Values-Motives Coherence at Work
Anna M. Zalewska, 161-172

A new workplace is a result of changing a work post or undertaking a new job. Direct indices of adaptation to this situation (average mood at the workplace and job satisfaction) and the indirect ones (costs like health complaints and the level of depressing or facilitating anxiety) are analysed with regard to reactivity and values-motives coherence at work. Sixty bank workers were investigated. The obtained results confirm that mood and costs depend on reactivity, but satisfaction with work depends on coherence. Only achievement values-motives coherence at work differentiates direct and indirect indicators of adaptation. Considering both kinds of variables modifies dependencies. Some theoretical and practical conclusions resulting from the research are included.

An Observation Method for Analyzing Operators' Routine Activity in Computerized Control Rooms
Lajos Izsó, Miklós Antalovits, 173-189

An activity analysis method was developed for studying the structure and dynamics of control room operators' activity during normal operation based on directly observable elements of the operators' behavior. The method assesses current activity along three dimensions in each 5-min period of the shift. Intensity characterizes arousal level, direction shows whether the activity is directed predominantly at the process control task, at something else, or miscellaneous. Motivation reflects if the activity is driven by intrinsic or extrinsic motivation. A case study is presented, in which 3 morning, 3 afternoon, and 3 night shifts of a Nuclear Power Plant operator crew are involved. The obtained results gave a deeper understanding of the operators' activity and also revealed an "arousal compensation" tendency.

Clogging of Filtering Material Systems Used for Disposable Respirators
Jacek Krzyżanowski, Katarzyna Majchrzycka, 191-202

The article shows the problem of clogging in connection with the parameters of filtering materials used in respiratory protective equipment. The results of investigations of airflow resistance changes during the depositing of dust inside the filtering material are presented. The configuration of layers differing in mass per unit area and the number of layers, were taken into consideration For each configuration, the clogging abilities and the changes of airflow resistance as a reason of loading with dust were assessed. The analysis of tested materials confirms the hypothesis that there is an important coincidence between the properties of the material used in filtering equipment and the clogging coefficient. The results show that the filter should have a layered structure and that the outer layer should be made of a nonwoven of relatively high surface density.

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