Multidisciplinary Design Optimization (MDO) has evolved as a discipline which provides a body of methods and techniques to assist engineers in solving large scale design problems. There are many frameworks for formulating MDO problems. These frameworks can be broadly classified as single-level or bi-level formulations. Collaborative Optimization (CO) is one of the popular bi-level formulations to solve an MDO problem. There are numerous design optimization problems which are highly CPU time intensive and require a long simulation time. With the advent of cheaper and faster available PCs, distributed parallel computer clusters have become very popular. These clusters provide large computing power and can be used to solve problems faster and more efficiently. This research is an attempt to take advantage of the computational power of parallel computers in the field of design Optimization. The robust design optimization of an Internal Combustion Engine has been formulated using CO and implemented using parallel computers. Considerable savings in Wall Time has been achieved. A generic strategy for solving similar problems has also been devised. A benchmarking program has also been developed to assess theoretical speedup for any problem size. This program uses the Collaborative Optimization framework and simulates a design optimization on distributed memory clusters.

Over the past decade increasing number of US companies have been encouraging the use of abdominal support as a part of their efforts to reduce the human and economic costs due to back injuries. Back belts are assumed to prevent injuries by restricting posture, increasing intra abdominal pressure, providing psychological effect and relaxing trunk muscle to provide circumferential support around the pelvis ring. This research deals in detail with the posture restriction caused by back belt. Two-dimensional kinematic data was collected from ten subjects using nine marker positions. Angular displacement of nine body angles was compared. The kinematic relationship, posture, and interjoint coordination were studied using knee, hip, trunk and thoracic-lumbar joint. Out of the nine body joint angles, five showed decreased flexion, three increased flexion and remaining one had no change. Kinematic relationship was not found to exist between hip, knee, trunk and thoracic-lumbar joint. The behavior of postural index values supported the failure of kinematic relationship hypothesis. The back belt was found to make coordination between hip, knee, trunk and thoracic-lumbar joint less perfectly simultaneous.

Since 9/11, airport security has become an area of critical national security. The current study investigates the effect of mental rotation training and the presence of visual decision aids on inspection performance. Forty-eight participants were divided into two groups (Group A and Group B) of twenty-four each. Each group was provided with training on visual inspection, baggage screening and on using the software simulation of airport baggage inspection. Participants had to identify from images any object that cannot be allowed on a passenger plane and register a response by clicking one of the buttons, Threat or No Threat. Participants in Group A were provided with visual decision making aids whereas participants in Group B were provided with none. Upon the completion of the first set of trials, all the participants underwent an advanced training session on mental rotation. The participants then repeated the same experiment as before. There was a significant interaction effect between training and rotation for response time, F(1, 184) = 8.59, p = .0038. Individuals that received no training and had rotated objects performed the worse compared to all other conditions. Response times for images with visual aids improves significantly (F(1, 184) = 20.74, p =0.0001) lower (M = 3.70 seconds, SD = 0.50) when compared to the response times for images after without visual aids (M = 4.03 seconds, SD = 0.53). Accuracy for images without training was significantly (F(1, 184) = 34.23, p < 0.0001) lower (M = 74.73, SD = 10.92) than the accuracy for images after training (M = 83.42, SD = 10.51). Accuracy for images presented without visual aids was significantly (F(1, 184) = 19.58, p < 0.0001) lower (M = 75.86, SD = 11.69) than the accuracy for images presented with visual aids (M = 82.29, SD = 10.51). The results from the experiment show that mental rotation has an effect on inspection performance of an airport baggage inspector and that the performance can be improved by training the inspector in mental rotation. It was also observed that providing visual decision making aids can improve the inspection performance.

This study examines the effect of an overhead drilling support and position of the arm on muscular activity of the shoulder. Five male participants simulated an overhead drilling task by using a drill in near, middle and far reach positions. Electromyographic measurements were taken from the dominant side anterior deltoid, bicep and trapezius muscles. Root mean square amplitude (RMS) of the EMG activity from these muscles was used to determine the load on the muscular system. The participants used a subjective rating scale to evaluate the overhead support stand and holding position. The results demonstrate that the overhead support stand was effective in reducing the muscular load. The mean RMS value reduction with overhead support stand, when compared to the without support in bicep muscles during near, middle and far reach positions were 18%, 24 % and 47%, respectively. For anterior deltoid muscles the percentage decrease in mean RMS values for near, middle and far reach positions were 24%, 33% and 49%, respectively; and for trapezius muscles the percentage decrease in mean RMS values during near, middle and far reach positions were 32%, 33% and 42%, respectively. The middle reach position, in contrast to near and far reach positions resulted in the lowest RMS values. The mean RMS values without support stand for biceps muscles was the lowest in middle position (0.139mv). Similarly the mean RMS values of anterior deltoid (0.231mv) and trapezius (0.066mv) muscles without overhead support stand were least for the middle position. The mean RMS values for the bicep (0.105 mv), anterior deltoid (0.155mv) and trapezius (0.041mv) muscles with overhead support stand were the lowest during the middle position. The subjective rating results also supported the above conclusions. These findings indicate that workers performing overhead drilling tasks in coronal plane should work in middle position in order to reduce the muscular load.

The objective of this study was to investigate the effect of repetitions on static and dynamic strength. The study is divided into two parts, the first part investigated static and dynamic strength during one, three and six repetitions per minute, and the second part of the study analyzed dynamic strength data collected using the Multiaxial Multipurpose Isokinetic Dynamometer. The study comprised of dynamic strength test data at three speeds of one, five and ten inch per second. Five male subjects participated in the first part of the study, and the results were analyzed by plotting a time series to observe the pattern of change in strength with repetitions. The results show a linear decrease in static and dynamic strength; the rate of decrease was the highest for static six repetitions per minute and the least during the dynamic one repetition per minute test. There was a decrease of 48.72% in strength for static six repetitions/minute routine and a decrease of 5.15% during dynamic one repetition per minute routine. Plot of Median Frequency (MDF) of EMG signals showed the highest rate of fatigue occurrence during static six repetition/minute and the least during dynamic one repetition/minute routine. The results of the second part of the study also show a linear decrease in dynamic strength for the three speeds. The highest percentage decrease in strength was 15.62% during one inch per second routine, and least decrease in strength was 8.7% during the ten inch per second pull routine. During the push cycle, the highest percentage decrease in strength was 18.56% during five inch/second routine and the least decrease was 8.28% during one inch/second. Another important fact is that all subjects were able to exert a maximum strength of 64.89 lb during five inch per second pull routine. This value was greater than the strength values exerted during one and ten inch per second push and pull routines. The MDF plot of the EMG signals showed the highest rate of fatigue occurred during five inch per second routine, and the least rate during one inch per second routine.

Generating the optimal production schedule for an assembly line, which will balance the workload at all the production stages, is a difficult task considering a variety of practical constraints. Varying customer demand is an important factor to be considered when designing an assembly line. In order to respond to varying customer demand, many companies are attempting to make their production system more flexible/agile or adaptable to change. Due to the volatile nature of market, companies cannot afford to manufacture same type of product for long period of time and neither can maintain high inventory level; to tackle this problem we propose a new approach of balancing mixed-model assembly line in a multi-level production system. The emphasis is on incorporating the effect of set-up times of lower production levels on the final assembly schedule. This will facilitate stabilized workload among and across the stations and effectively balance the production schedule at all production stages. As a result, the proposed model assures that workloads are balanced and setup times are reduced to such an extent that WIP and overall inventories are kept to a low level.

Because of the common occurrence of pain experienced by dental professionals during the course of a workday and throughout their career, an epidemiological and a field study were performed in an effort to contribute to the prevention of musculoskeletal disorders in dentistry. The aim of the thesis is two fold: to assess the perception of occupational pain and discomfort felt by dentists through a perception based survey and to assess the muscle behavior of dentists during isotonic postures while performing various dental procedures on their first and last patients in a given work day. One hundred (100) dentists participated in the survey and ten (10) dentists out of the same sample group participated in the field study. Eight (8) EMG measurements were taken per dentist (four measurements per area of the back during the course of the day): representing lower back and upper trapezius EMG during the first minute of the first patients visit and lower back and upper trapezius EMG during the last minute of the first patients visit. The results of the survey indicate that fifty-eight percent of all of the respondents reported that they experience or have experienced some form of pain in their lower back, shoulder or neck during their tenure as a practicing dentist. Sixty-nine percent stated that the pain is such a real issue that they work out regularly to avoid it. Forty-seven percent report that they find comfort and muscle relaxation through massages and massage therapy. The development of muscle fatigue was assessed by spectral analysis (median frequency). It was found that the median frequency decreased significantly in the upper trapezius muscle from the last minute of the first patient to both the first and last minutes of the last patients. Perception of pain was found to have a significant relationship with the change in EMG frequency recorded after both 4 and 8 hours of work.

In this thesis, two data sets collected in grinding process under different cutting and wheel conditions were studied. One is the cutting forces in three directions, i.e. X, Y and Z, collected under two different cutting conditions. The other one is the acoustic emission (AE) signals collected under different wheel conditions(sharp and dull). For the goal of grinding wheel condition monitoring, the regression model with autocorrelated errors was proved to be effective and was used to extract features from signals in this study. The coefficients of the models served as the features used in the classification step that employed boosting method. Based on the AdaBoost and A-boosting algorithms which can only be used in two classes situation, two improved boosting methods called Adaboost-M and A-boosting-M, which can be used to classify multiple classes, are proposed. With the forces data set, we compared Adaboost-M and A-boosting-M against the traditional AdaBoost.M1 and the corresponding weak learners(KNN and Prototype). The accuracies of Adaboost-M and A-boosting-M are higher than that of AdaBoost.M1 and the weak learners in our application. With the AE data set, our focus is to recognize the signals collected when the wheels were dull from the signals collected when the wheels were sharp. The AdaBoost, A-boosting and the corresponding weak learners(KNN and Proto) were used. The results indicate that (i) boosting does not improve the effectiveness of k-nearest neighbor but greatly improve the effectives of the prototype classifier, (ii) depending upon the data, AdaBoost or A-Boosting might produce higher classification accuracy, (iii) the error of false positive is higher than the error of false negative for the better classifiers. Based on the study, the combined use of AR models for feature extraction and boosted algorithms for classification are proved to be a viable approach for grinding wheel condition monitoring.

This thesis studied the temperature circadian rhythm and its relationship with the physical and mental performance of the individuals. The objectives of this study were to determine (1) the effect of temperature circadian rhythm on the mental and physical performance, (2) whether a common oral temperature circadian rhythm pattern exists for all the participants, (3) the times of the day when the participants perform their best and worst in comparison to their highest and lowest temperatures respectively, (4) find out whether the effect of the oral temperature circadian rhythm on the physical and mental performance is different in males and females, and (5) the effect of lunar cycle on the physical and mental performance. In order to achieve the above-mentioned objectives, ten participants (5males and 5 females between the ages of 20-28 years) were tested. Each participant was required to record his/her body temperature every hour over a 13-hour period for about a week. Based on this data, the participants' highest and lowest temperatures were determined. Each participant was given a physical and a mental performance test at the times corresponding to his/her highest and lowest temperatures. Finally, the lunar calendar was used to test the effect of the lunar cycle on the physical and mental performance of the participants. The results of the experiment show that during the time corresponding to high oral temperatures, the participants' physical performance increased by 9.3 percent, and the mental performance increased by 4.6 percent compared to their low temperatures. The participants, upon analysis of the data, also exhibited a common pattern in their temperature circadian rhythms. The results showed that on average, the participants' body temperature started increasing around 9:30am and kept increasing until 8:30pm. In addition to that, it was also found out that there was an insignificant difference in the average physical performance increase in males (9.38lbs) and females (9.39lbs); however, mental performance increased by a greater percentage, in females (5.2) as compared to males (4.07). Finally, the lunar cycle had no effect on the physical and mental performance of the participants.

In todays competitive world, the unit cost of a high-tech product declines significantly over its life cycle. An integrated inventory model for products experiencing continuous decrease in unit cost is studied in this research. In this integrated model a manufacturing facility purchases raw material from outside supplier at a fixed size and supplies a fixed quantity of finished products to a buyer periodically after using its production processes. Moreover, buyers demand frequent deliveries of small lots of finished products since the price is continuously decreasing, and this emphasizes the significance of just-in-time (JIT) inventory management for successful companies in technology-related industries. The goal in this study is to minimize the total cost of the supply chain in JIT environment while the price of the high-tech product is linearly decreasing over its life cycle. A cost model composed of manufacturers raw materials and finished goods and buyers incoming goods inventory costs is developed here. An efficient algorithm is employed to determine the optimal or near-optimal lot sizes for raw material procurement, manufacturing batch and buyers ordering policies. It is also shown in the implemented model that the integrated total cost over the planning horizon considers the changing prices at each replenishment for both manufacturers and buyer s inventory costs. Consequently, in this article, the traditional integrated inventory model is relaxed by removing the restriction of constant unit cost. Finally, the solution technique for the developed model is illustrated with numerical examples, and compared with the previously developed integrated inventory models to test its accuracy. It is proven that the model is accurate and effective for the inventory systems with decreasing unit cost.