Majid Jaraiedi

Prediction of overexertion injuries using biomechanical and psychophysical models

This paper summarizes a three year epidemiological study conducted in five large industrial plants in order to evaluate the validity of two alternative modeling approaches to overexertion injury prediction. Detailed biomechanical and psychophysical job evaluations were performed for 55 industrial jobs comprised of 2934 potentially stressful manual materials handling tasks. The medical experiences of 6912 incumbent workers were monitored retrospectively for two years and prospectively for one year to establish a data base for comparison of the different models. The results show that each of the models can be used to predict both the incidence and severity of certain overexertion types of injuries such as contact, musculoskeletal and back injuries. The application of these models to identify or design administrative and engineering controls, however, may be limited as a result of the inherent correlation between the available indices and multifaceted jobs.

Total Quality Management Applied to Engineering Education

A methodology demonstration using Quality Function Deployment (QFD) as a tool to explore some key elements of higher education. QFD is most commonly applied in industrial settings where products are manufactured. This research applies QFD to a service, specifically engineering education. The goal of this research is, therefore, twofold. While exploring the quality of engineering education in a university setting, a new application of QFD was tried and tested. Considering the university students as the primary customers, the results of a nominal group technique session, along with interviews of faculty members and administrators were used to define “the voice of the customer”. QFD procedures and forms were used to analyse and scrutinize the specific areas of advising and teaching within the university. Recommendations were devised which range from a comprehensive instructor‐training programme to self‐help and mentor programmes by student groups.

Effect of lumbar posture on lifting.

Twenty laborers assumed specific lumbar spine postures and lifted a 157 N crate to three different hand heights to determine if lumbar spine flexion moments or trunk muscle activity were affected by the lifting postures. Lumbar flexion moments were lowest when the workers used the lordotic and straight back postures, while the average erector spinae muscle activity tended to be highest in the lordotic and straight back postures. The kypohotic posture regularly reduced the activity of the erector spinae to bursts of activity while lifting and caused more discomfort during the lifting tasks than any other posture. Therefore, the lumbar lordotic posture is recommended as the posture of choice while lifting, particularly when lifting from the floor level.

Multiple Inspections to Meet Desired Outgoing Quality

This paper presents a model which can be used to determine the Average Outgoing Quality for a product which has multiple quality characteristics and which is subjected to multiple 100% inspections where the inspection is subject to errors. It allows the..

Manual Dexterity Evaluation of Gloves Used in Handling Hazardous Materials

The problems associated with hazardous materials control are numerous and complex. One of these problems involves selecting hand protection which will resist permeation for the duration of the exposure while maintaining sufficient levels of dexterity and tactility so that the worker can safely and efficiently perform the required task. This study investigated the effect of nine glove combinations on manual dexterity. These included three single glove and six double glove combinations plus the bare hand condition. The subjects performed a nut-bolt-washer assembly-dissassembly task using the Bennett Hand Tool Dexterity Test apparatus. The task required the use of a screw driver, two sizes of open-end wrenches, and an adjustable wrench, along with handling the bolt, nut, and washer while performing the assembly-disassembly task for three different bolt, nut, and washer sizes (1/2″, 5/16″, 1/4″). The response variables measured in the experiment were the time to complete each task and number of errors committed during each task. An error was defined as a drop of any of the items handled. The data was analyzed using a fixed effects randomized ANOVA model and the Duncans Multiple Range Test. An alpha level of 5 per cent was used in the analysis. The results of the analyses showed that gloves increased the average completion time by 15 to 37%. Several double gloving combinations had significantly longer task completion times compared to single gloves.

Effectiveness of Fit Check Methods on Half Mask Respirators

Abstract Studies were conducted to evaluate whether a positive/negative (+/-) fit check was an effective aid in helping users of respiratory protective equipment (RPE) achieve a good fit when donning the RPE. Two types of half-facepiece RPE were used in the studies: the disposable, filtering facepiece and the elastomeric facepiece. Three models of disposable, filtering facepiece and one model of dual-cartridge, elastomeric facepiece were evaluated. A population of 64 inexperienced users of RPE was randomly divided into two equal groups. One group was trained to don the RPE using the +/- fit check as an aid, while the second group was trained to don the RPE without conducting a +/- fit check. The number of successful RPE donnings achieved in the group using the fit check was compared with the number of successful RPE donnings achieved in the group not using a fit check. The data obtained from this experiment suggested that, in general, fewer unsuccessful donnings and more consistent donnings were obtained ...

Modelling long-run cost minimization and environmental provisions for utility expansion

A realistic long-run cost minimization model for electric power expansion is presented. The model uses mixed integer and dynamic programming methods to minimize electric power costs while considering alternative generation technologies and fuel choices and satisfying demand, the environmental regulations of the Clean Air Act Amendment (CAAA) of 1990 and reliability constraints. The model can be used to produce the optimal production schedule for a combination of existing and projected new plants. Actual data from a large eastern US utility are used to provide a realistic test of the model and to reach conclusions about the optimal path to take to comply with the CAAA. Application of the model to these data indicates that in order to comply with the CAAA, fuel switching is preferred over scrubbing the flue gases. For this case, fuel switching proved to be 9.5% less costly than scrubbing.

Prediction of elderly seating comfort from physical condition, chair type and gender

Many persons over 60 years of age have unique problems sitting on chairs. These problems which are caused by decreased mobility, strength or disease suggest that the chairs should be selected carefully with some scientific basis that incorporates the varying demands of the elderly community. Identification of the proper chair for a particular individual, especially if it has to be low cost and nonmotorized, is a difficult job for institutions, elderly themselves, their families and the furniture industry. Keeping in view these problems a prediction model is developed using established statistical methods to predict comfort of sitting of a particular individual sitting in a particular chair. The study is based on experimental data collected on 18 male and female subjects over the age of 64. The equation uses chair type, body fat %, i.e. above average fat etc., body size, i.e. lean etc., and gender as inputs. The equation was tested on new female and male elderly subjects sitting on two new chairs. The model holds out excellent on the validation despite a low coefficient of determination value obtained for the equation. The paper not only presents a comfort prediction model but also shows a new direction for elderly seating research by employing statistical methods and elderly variables which do not appear in the published literature on elderly seating in the manner presented in this paper. This model will have wide applications especially for practioners (e.g., human factors engineers, occupational therapists, product developers) who need such information in a hurry. This approach also has heuristic value for the researcher in providing guidelines for the testing of other critical variables that may impact on the use of a chair or of other pieces of equipment.

Tracking signal test to monitor an intelligent time series forecasting model

Extensive research has been conducted on the subject of Intelligent Time Series forecasting, including many variations on the use of neural networks. However, investigation of model adequacy over time, after the training processes is completed, remains to be fully explored. In this paper we demonstrate a how a smoothed error tracking signals test can be incorporated into a neuro-fuzzy model to monitor the forecasting process and as a statistical measure for keeping the forecasting model up-to-date. The proposed monitoring procedure is effective in the detection of nonrandom changes, due to model inadequacy or lack of unbiasedness in the estimation of model parameters and deviations from the existing patterns. This powerful detection device will result in improved forecast accuracy in the long run. An example data set has been used to demonstrate the application of the proposed method.

Posterior Analysis of Inspector Accuracy

Signal Detection Theory (SDT) has recently been used to evaluate the performance of imperfect inspectors. SDT model is based on a priori probabilities and perceived payoffs and penalties to study inspectors′ behaviour. In this article, Bayes′ theorem is used to compute posterior probabilities of the two types of inspection error. These posterior probabilities give rise to the definition of Receiver Analysis Curves (RAC), which depict the “after the facts” consequences of inspection error. A cost model is also developed that reflects the true benefits and costs of inspection accuracy to the organisation.