Hutchinson, Francis Williams, B.G.S., Louisiana State University, 1989 Master of Science in Industrial Engineering, Summer Commencement, 2012 Major: Industrial Engineering Evaluation Of Methods To Operate Gate Valves Using Elapsed Time, Rating Of Perceived Exertion, And Electromyography Thesis directed by Professor Fereydoun Aghazadeh, Ph.D., PE Pages in thesis, 86. Words in abstract, 253. ABSTRACT Industrial valve handwheels are in common use in many industries to block, allow, or regulate the flow of materials within a system. Significant numbers of musculoskeletal disorders have been attributed to turning valve handwheels. The torques encountered to break and/or turn these handwheels often exceeds 100 Nm and therefore necessitate the use of special wrenches or other aids. The literature reveals that most of the research has been done to determine the operators capabilities for developing the breaking forces. After breaking, the continuous muscular effort for as much as five to fifteen minutes required to fully open or close some valves is believed to place greater demands physically and physiologically on the operator than the initial breaking torque requirement. This study used electromyographic data taken from two different locations, the elapsed time to fully open a valve, and Borgs subjective Ratings of Perceived Exertion (RPE) obtained from the participants to determine the optimum method for opening the valve. The data was obtained from a group of 10 participants who fully opened the valve by using their hands only, using a conventional valve wrench, and using a modified valve wrench. The tasks were repeated with the valve wheel set at two different torque requirements: 25Nm and 50Nm. The data gathered was then analyzed and evaluated to determine if the modified wrench was the optimum method to open the valve. Although the modified wrench was demonstrated to be the most efficient under some conditions, advantages from further testing and modifications to the wrench were indicated.

The occupational injury rate in the manufacturing sector is higher than the average of all private industries, necessitating safety studies. Occupational safety can be measured through different approaches. Safety climate, a predictive measure of safety, studies the workers perceptions of safety of the workplace. This measure includes several dimensions of safety like management commitment, involvement and work place hazard evaluation and was chosen as a method of evaluation in this study. Even though occupational safety is an important concern, management often prioritizes reducing waste and cost. So, there is a necessity for some technique which reduces waste and simultaneously improves safety. Lean has been effective in reducing waste and costs. Researchers have shown that lean might improve occupational safety too. Nevertheless, empirical evidence to prove the relationship between the two is insufficient. In this study, 5S, a lean technique, was implemented in a manufacturing company and its impact on safety climate of the workers was studied to show the relationship between lean and safety climate of the workers. Case and control groups took the Safety Climate Assessment Toolkit, a safety climate questionnaire, both before and after the 5S event. The effectiveness of the 5S event was determined through three productivity measures (cycle time, floor space utilized, ratio between inventory and units produced). Statistical analysis showed that the safety climate of the manufacturing workers increased after the 5S event (p value = 0.0085). The 5S event was also shown to be effective. The cycle time was reduced by 16.6% and floor space utilization decreased by 22.2%. 5S not only improved the processes by reducing waste and costs, but also improved the safety climate of workers.

The thesis addresses the problems faced by contractors during the recovery and rebuilding process after hurricanes that struck the southeast region of the United States in 2004-2005 hurricane seasons. It also deals with the practices they normally use to solve such problems. First, through literature review, six possible problems were identified, which were then used to gather information about the major problems faced by the construction industry in post-hurricane projects. The possible problems were site logistics, material transportation, labor, political influences, building permits and site location. Data were then collected via surveys of 450 contractors involved in post-hurricane construction in Alabama, Florida, Louisiana, Mississippi, North Carolina, South Carolina and Texas. The analysis showed that three of those problems - site logistics, labor and material transportation were identified as major problems among the respondents. The remaining were considered as problems, but not major ones in post-hurricane reconstruction projects. The study recommends practices, such as better planning, scheduling, coordination, supply chain management and use of experienced site personnel, for tackling the problems of site logistics and material transportation. Outsourcing labor was one of the methods suggested to improving conditions with regards to labor problems. The research identifies the problems and provides a list of possible solutions to these problems, as used by the contractors of such projects. Therefore, by using the suggested practices, post-hurricane reconstruction projects can be beneficial for contractors, and the outlook towards these projects as being less profitable can be changed.

Multi-criteria decision-making (MCDM) is one of the most widely used decision methodologies in the sciences, business, and engineering worlds. MCDM methods aim at improving the quality of decisions by making the process more explicit, rational, and efficient. One intriguing problem is that oftentimes different methods may yield different answers to the same decision problem. Thus, the issue of evaluating the relative performance of different MCDM methods is raised. One evaluating procedure is to examine the stability of an MCDM methods mathematical process by checking the validity of its proposed rankings. The ELECTRE II and III methods are two well-known MCDM methods and widely accepted in solving MCDM problems in civil and environmental engineering. However these two methods have never been studied in detail for the validity of their proposed rankings. Thus, the first aim of this thesis is to examine if these two methods suffer of any type of ranking irregularities and analyze the reasons of the phenomenon. As the research results in this thesis revealed, the ELECTRE II and III methods do allow some types of ranking irregularities to happen. For instance, these two methods might change the indication of the best alternative for a given MCDM problem when one of the non-optimal alternatives was replaced by a worse one. The two methods were also evaluated in terms of two other ranking tests and they failed them as well. Two real-life cases are described to demonstrate the occurrence of rank reversals. Then reasons behind the phenomenon are analyzed. Next an empirical study and some real-life case studies were executed and discussed. The results of these examinations show that the rates of those ranking irregularities were rather significant in both the simulated decision problems and the real-life cases studied in this research. However, some recent studies showed that rank reversals could also happen because people may reverse their preferences due to some emotional feelings, like regret and rejoicing. Thus this thesis proposes a new MCDM method which is based on regret and rejoicing. This new method is expected to satisfy a set of critical conditions.

This thesis develops a computer-aided weld inspection methodology based on fuzzy modeling with selected features. The proposed methodology employs several filter feature selection methods for selecting input variables and then builds fuzzy models with the selected features. Our fuzzy modeling method is based on a fuzzy c-means (FCM) variant for the generation of fuzzy terms sets. The implemented FCM variant differs from the original FCM method in two aspects: (1) the two end terms take the maximum and minimum domain values as their centers, and (2) all fuzzy terms are forced to be convex. The optimal number of terms and the optimal shape of the membership function associated with each term are determined based on the mean squared error criterion. The fuzzy model serves as the rule base of a fuzzy reasoning based expert system implemented. In this implementation, first the fuzzy rules are extracted from feature data one feature at a time based on the FCM variant. The total number of fuzzy rules is the product of the fuzzy terms for each feature. The performances of these fuzzy sets are then tested with unseen data in terms of accuracy rates and computational time. To evaluate the goodness of each selected feature subset, the selected combination is used as an input for the proposed fuzzy model. The accuracy of each selected feature subset along with the average error of the selected filter technique is reported. For comparison, the results of all possible combinations of the specified set of feature subsets are also obtained.

The construction industry has one of the highest incidents of fatal and non-fatal accidents/injuries every year. As a high risk industry, there is a need to investigate factors that affect the occurrence of these accidents to be able to protect workers. Traditional approaches to workers safety in the construction industry have focused on the physical and biomechanical aspects of work by improving tools, equipment and task completion methods. However, the impact of psychosocial factors, specifically stress as experienced by construction workers is an area of growing research. Research in the area of occupational stress in the Construction Industry is yielding results that suggest that overall work safety on the construction site, should take into account psychosocial aspects of work. Research is carried out to investigate the relationship existing among occupational stressors, psychological/physical symptoms and accident/injury and work days lost outcomes as experienced by industrial construction manual workers engaged in a range of construction occupations. Workers perceptions about stress levels on specific elements of work as well as responses about physical/psychosocial symptoms were obtained by administering a questionnaire adapted from previous research. Analysis of the data entailed investigation of relationships through correlation and regression analysis, existing between the levels job stressors as experienced by the workers and (a) Company Accident History (OSHA-300 form) reports (b) Employee self-reported injuries and (c) Lost work days in 12 months prior to the survey. Among the occupations surveyed, pipefitters were at the highest risk for getting injured and responded with the most negative levels of occupational stressors. Some of the occupational stressors significantly associated with self-reported and OSHA logged injuries were training, job certainty and safety climate of the company. The OSHA logged injuries were associated with the occurrence of headaches and feelings of tenseness on the job.

In recent years, collaboration in supply chain approach widely discussed in the literature; but most have dealt with the two-echelon systems. This study focuses on the just-in-time delivery policy of three-echelon supply chain by collaborative approach, where any of the information from the supply chain is available to all the subsystems involved; manufacturer, distribution center and retailer. In the first part of the study a simple model has been developed for a three-echelon supply system that consists of a single manufacturer, a single distribution center and a single retailer. The other part of the study extends this model by considering a upstream integrated delivery supply chain system consisting of a single manufacturer, multiple distribution centers and multiple retailers. In both cases the retailer enjoys a permissible delay in payment. The joint annual cost of the supply chain is obtained by summing the annual relevant costs at all the subsystems. Using the convex property of the cost function, the optimum values of the decision values are initially obtained that minimizes the total cost. Then, these values are adjusted according to feasibility criteria of the credit conditions and other constraints using an algorithm. A numerical example illustrating the solution reveals that total supply chain cost is less by the presented collaborative approach compared to typical delivery policy. A sensitivity analysis also showed the robustness of the new model. This model considers lot-splitting and deferred payment simultaneously. That has not been studied for three-echelon system before. Future extension of this study involves assumption of random demand with cross-transfer delivery, unequal cycle time, shortage consideration, etc.

Friction Stir Welding (FSW) is a solid state joining process that uses a non-consumable rotating welding tool to generate frictional heat at the welding location. Large forces are required to produce friction between the welding tool and the work piece which increases the wear rate of the welding tool in welding materials with high melting temperature. Several different approaches have been developed to address this problem. This thesis focuses on a new modification of friction stir welding, called Laser Assisted Friction Stir Welding, a process developed in the last decade. This process uses laser energy to preheat the work piece at a localized area ahead of the rotating tool, thus softening a volume of the work piece ahead of the tool. The work piece is then joined by the rotating tool as in conventional FSW. The amount of heat generated during welding determines the quality of the weld. Hence understanding the temperature distribution is necessary in determining the optimum process parameters for the welding process. In this thesis, a three dimensional model of laser assisted friction stir welding is developed, using FLUENT which is based on finite volume method, to obtain the temperature distribution in the work piece. The developed model can be used to better understand the process, predict the process performance and to determine optimal process parameters. A comparison with pure friction stir welding without laser assistance is also made to show its potential benefits. Parametric studies are designed to understand the effect of variation of certain process parameters such as feed rate, tool rotational speed and laser heat input on temperature distribution in the work piece. Finally, optimal combinations of friction stir welding and laser parameters are determined by a metaheuristic - Ant Colony Optimization.

Forest logging is the process in which trees are cut down for forest management and/or timber harvest. According to OSHA, logging is the most dangerous occupation in the United States. It consistently represents one of the most hazardous industries, with a fatality rate more than 21 times higher than the rate for all workers in the United States. Yet, little research has been performed to determine the long term effect of noise on forest loggers. OSHA regulations state that the maximum permissible hearing in an 8 hour shift should not exceed 90 dB. Occupational noise exposure is recognized as a primary factor on permanent hearing loss (OSHA, 2007). The objective of this study is to determine whether long term hearing loss in forest loggers is associated with noise emitted by logging equipment. This study compares the differences in hearing thresholds of the participants, applying the OSHA age correction tables for audiograms (OSHA, 2008). These tables present the hearing threshold of a normal population at ages ranging from 20 to 60 years. Hearing threshold shift is determined by subtracting the hearing threshold of each participant from age corrected hearing threshold as defined by OSHA (2008) for each specific age. These individuals had never experienced any type of acute or chronic hearing loss. Participants were also separated into age groups of 10 year intervals (20 to 29, 30 to 39, 40 to 49, and 50 to 59) and experience groups of 10 year intervals (1 to 10, 11 to 20, 21 to 30, and 31 to 40). The hearing tests on forest loggers determined that at 4000 Hz, the mean hearing threshold of the participants was significantly higher than the rest of the frequencies. Furthermore, a significant increase in hearing threshold between the participant population and the hearing threshold of a normal population was also determined. The hearing threshold shifts at 1000, 2000, and 4000 Hz were of 4.9, 9.5 and 18.0 dB respectively. A significant decrease in the hearing threshold (of 3.4 dB) was found between those participants who wore hearing protection and those who did not.

Demands at work are associated with an increased risk of cardio vascular diseases, but little is known about its underlying connection. The purpose of this study was to evaluate the effects of physical and mental tasks that induced stress, on Heart Rate Variability (HRV). Another aim was to observe the trends in subjective workload ratings in conjunction with the physiological response of the heart and also to assess the comfort level of the participants while wearing the heart rate monitor and performing tasks. Heart rate was recorded while at rest and while performing the tasks. Subjective workload ratings were obtained from NASA-TLX and the comfort scores from a comfort questionnaire for each task. The power spectral components HF, LF, LF/HF and the time domain RMSSD, were used as the components of HRV in the analysis. The results indicated that all the components of HRV examined were sensitive to physical and mental demands. The HF and RMSSD components decreased with increase in demands from the baseline values. The LF and the LF/HF ratio increased with increase in demands. Overall results indicated reduction in HRV when demanding physical and mental tasks were performed. Subjective workload ratings changed in accordance with the physiological response. Subjective workload rating was high for both the tasks. Overall comfort score indicated that the participants were comfortable while wearing the heart rate monitor and performing the tasks. The evidence from this study suggested that these simulated work factors (physical and mental demands) influence risk factors that may increase risk for CVDs in work places. It is recommended that future research be conducted in the field to quantify HRV and the workplace/tasks be redesigned to reduce excessive physical and mental demands.