Wafik H. Iskander

Workplace Protection Factor Measurements on Powered Air-Purifying Respirators at a Secondary Lead Smelter: Results and Discussion

A study was conducted at a secondary lead smelter to evaluate the workplace performance of the 3M W-344 and Racal AH3 powered air-purifying respirators equipped with helmets and high efficiency filters. The research protocol developed for the study has been described in a companion paper. The results of the study indicate that the mean lead concentrations, measured inside the facepiece of both PAPRs, were significantly less than the OSHA lead exposure limit of 50 micrograms/m3. The means of the workplace protection factor measurements on both PAPRs were significantly less than the PAPR selection guide protection factor classification of 1000. Correlation analysis of preshift quantitative fit factors and corresponding workplace protection factors indicated no linear association between these two measures of performance. This finding suggests that for PAPRs equipped with helmets and high efficiency filters quantitative fit factors as presently determined are not indicative of the workplace protection which the respirators provide. Since the PAPR protection factor classification of 1000 was originally based on quantitative fit factors, the lack of a demonstrated association between quantitative fit factors and workplace protection as found in this study may explain why their performance was significantly less than expected.

Correlation Between Respirator Fit and Respirator Fit Test Panel Cells by Respirator Size

The National Institute for Occupational Safety and Health (NIOSH), recognizing the difficulties inherent in using old military data to define modern industrial respirator fit test panels, recently completed a study to develop an anthropometric database of the measurements of heads and faces of civilian respirator users. Based on the data collected, NIOSH researchers developed two new panels for fit testing half-facepiece and full-facepiece respirators. One of the new panels (NIOSH bivariate panel) uses face length and face width. The other panel is based on principal component analysis (PCA) to identify the linear combination of facial dimensions that best explains facial variations. The objective of this study was to investigate the correlation between respirator fit and the new NIOSH respirator fit test panel cells for various respirator sizes. This study was carried out on 30 subjects that were selected in part using the new NIOSH bivariate panel. Fit tests were conducted on the test subjects using a PORTACOUNT device and three exercises. Each subject was tested with three replications of four models of P-100 half-facepiece respirators in three sizes. This study found that respirator size significantly influenced fit within a given panel cell. Face size categories also matched the respirator sizing reasonably well, in that the small, medium, and large face size categories achieved the highest geometric mean fit factors in the small, medium, and large respirator sizes, respectively. The same pattern holds for fit test passing rate. Therefore, a correlation was found between respirator fit and the new NIOSH bivariate fit test panel cells for various respirator sizes. Face sizes classified by the PCA panel also followed a similar pattern with respirator fit although not quite as consistently. For the LANL panel, however, both small and medium faces achieved best fit in small size respirators, and large faces achieved best fit in medium respirators. These findings support the selection of the facial dimensions for developing the new NIOSH bivariate respirator fit test panel.

A simulation model for a same day care facility at a university hospital

A simulation model was developed to evaluate the adequacy of the ambulatory care center space planned for the same-day care center at West Virginia University Medical Center. After thorough testing, the model was implemented, and results were obtained for different scenarios and modes of operation. Based on the results produced, officials at the hospital altered their original design and moved some of the services to the main hospital. After the study was performed, construction was completed for the outpatient care facility, and the same-day care unit was moved into it under the split service arrangement recommended from the analysis of the simulation results. After several months of operation, real-life results confirmed those predicted by the model.<<ETX>>

Simulation Modeling For Emergency Medical Service Systems

A simulation model was developed with the purpose of providing EMS planners and managers with a tool to help them in the planning of their operations and in their decision making role in general.The model was successfully tested on one of the seven EMS regions in the state of West Virginia. Policy changes were tested by running the model under different conditions, and measuring their impact on the performance of the EMS system. Policies investigated include the elimination and addition of squads, reallocation of vehicles, and changing the level of personnel training and preparedness.

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.

Strategic Planning for Capacity in Power Distribution Grids

ABSTRACT Utility planners strive to develop a distribution network which provides economic, reliable, and safe electric energy to the end users. Since the power demand has a tendency to grow, utility companies must cope with the increasing load by continuously upgrading the existing substations and power lines in the grid, or by adding new ones. An alternative solution is to add energy storage and generation sources that are located closer to the customers. This article presents a summary of a research conducted at the Department of Industrial and Management Systems Engineering at WVU pertaining to capacity planning in a deregulated environment. In this research, an integrated approach to the grid planning was considered, where distributed generation (DG) sources and energy storages (ES) are incorporated into the expansion plan together with traditional options. The objective is to minimize the present worth of installation, upgrade, operation and maintenance, customer interruption, and fuel costs during ...

A principal-components approach to assign confidence intervals in steady-state simulation

This paper presents an approach to the assignment of a confidence interval to the mean of a stream of autocorrelated output data from a steady-state simulation run. Based on the principal-components analysis method, the approach is to derive a linear transformation of the data that yields approximate independence of the transformed data. To aid convergence to normality (on which the confidence interval is based) and to keep the dimension of the transformation reasonable, the original output data are batched prior to performing the transformation. The approach is fairly simple to understand and to implement, and experimental results indicate that it may perform better than the non-overlapping batch means method in terms of coverage with any number of batches.

Development and implementation of a risk analysis procedure

A detailed procedure is given for the development and implementation of a risk analysis to protect the operations of an enterprise from all types of threats . This procedure includes the performance of assets analysis and threat analysis, the analysis of the annual loss expectancy, the identification of security measures, and the evaluation of these measures.

Quality Value Function and Consumer Quality Loss

This paper presents a study of consumer evaluation and assessment of product quality. Consumers experience a loss due to quality discrimination because they pay same price for a product but get different quality. Quality value function is determined by consumer preference for product quality in a deterministic manner. This paper derives expected quality value and consumer-based quality loss which depend on the form of the quality value function employed.