Browsing by Subject "Work -- Physiological aspects"
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Item A comparative study of some physiological parameters of static and dynamic work performed by the upper limb(Texas Tech University, 1967-08) Purswell, Jerry Lee.Item A simulation of selected low coal mining tasks(Texas Tech University, 1980-12) Morrissey, Stephen JamesNot availableItem Alternative strength testing methods for employee screening(Texas Tech University, 1983-12) Plott, Christopher CNot availableItem Design and evaluation of a mailbag for mailcarriers(Texas Tech University, 1984-05) Ashton, Nina ANot availableItem Design and evaluation of a micro-climate cooling system using a vest with ice bags(Texas Tech University, 1986-05) Tayyari, FariborzA microclimate cooling system was designed in this dissertation project. The system consists of a vest with 54 small ice bags inserted in the pockets sewn to the Inside of it. The system was tailored in such a way as to open and close in front (to be worn as a vest) and on both sides (to be worn as a poncho). The effectiveness of the designed cooling system with (DCSS) and without (DCSN) a slicker worn over it, and a South African cooling system (SACS) in reducing heat stress encountered by men working in hot environments was evaluated. Testing was conducted in an environmental control chamber to simulate hot-humid and warm-humid environmental conditions. Two workloads, moderate and heavy, were performed by the four subjects who participated in this project. Under the hot thermal condition the average tolerated exposure time by the subjects when not using a cooling system was 72.5 minutes when they performed the heavy workload, and 85 minutes when performing the moderate workload. But, when the cooling systems were utilized, all subjects completed the 95-minute work sessions. Under the warm condition the subjects were able to complete all work sessions even without a cooling system. The effectiveness of the cooling systems in reducing physiological strains and subjective responses (i.e., the feeling of discomfort and thermal sensation), especially under the hot condition, was statistically significant. It was concluded that both the cooling system designed for this study and the South African cooling system were effective in reducing the heat stress associated with working in the hot-humid condition investigated in this study. It was also concluded that the performance of the designed cooling system was better than that of the South African cooling system and the best results were achieved when a slicker was worn over the designed cooling system.Item Effects of running with backpack loads during simulated gravitational transitions: improvements in postural control(Texas Tech University, 2003-12) Brewer, Jeffrey DavidThe National Aeronautics and Space Administration is planning for long-duration manned missions to the Moon and Mars. For feasible long-duration space travel, improvements in exercise countermeasures are necessary to maintain cardiovascular fitness, bone mass throughout the body and the ability to perform coordinated movements in a constant gravitational environment that is six orders of magnitude higher than the "near weightlessness" condition experienced during transit to and/or orbit of the Moon, Mars, and Earth. This research provides insight for maintaining the ability of astronauts to perform coordinated, bipedal locomotion activities, following transitions between gravitational acceleration fields. In addition, a unique environmental simulator has been developed which enables further research regarding the complex interactions between humans and the environments in which they move. In order to investigate methods of improving postural control adaptation during these gravitational transitions, a treadmill based precision stepping task was developed to reveal changes in neuromuscular control of locomotion following both simulated partial gravity exposure and post-simulation exercise countermeasures designed to speed lower extremity impedance adjustment mechanisms. The exercise countermeasures included a short period of running with or without backpack loads immediately after partial gravity running. A novel suspension type partial gravity simulator incorporating spring balancers and a motor-driven treadmill was developed to facilitate body weight off-loading and various gait patterns in both simulated partial and full gravitational environments. Studies have provided evidence that suggests: (1) the environmental simulator constructed for this dissertation effort does induce locomotor adaptations following partial gravity running; (2) the precision stepping task is a sensitive test for illuminating aspects of these adaptations; and (3) musculoskeletal loading improves the locomotor adaptation process.Item Evaluation of anaerobic threshold for lifting tasks(Texas Tech University, 1983-12) Intaranont, KittiAn experiment was designed and conducted to accomplish the following objectives: 1. Comparison of the maximum V02 values, as measured during an arm cycling task, a bicycling task, and lifting activities, 2. Comparison of the anaerobic threshold (AT), as measured during an arm cycling task, a bicycling task, and lifting activities, 3. Development and testing of a mathematical model for the prediction of the lifting capacity using the criterion of an individual’s anaerobic threshold. A submaximal exercise protocol was applied to predict the aerobic capacity (V02 max or PWC). A graded exercise protocol using successive weight increments was applied to predict the AT. The dependent variables were the predicted maximum permissible (lbs.) of lift at 90% of the AT and the anaerobic threshold (1/min. of O2). The independent variables were task and individual variables. The task variables were ranges of lift (floor to knuckle height and knuckle to shoulder height) and frequencies of the lift (6, 7.5, and 9 lifts/min). The individual variables included body weight, lean body weight, and the PWC values predicted from bicycling and arm cycling. Ten make subjects, 10-27 years of age, participated in the experiment. The collection of physiological data began after a familiarization period. The results of the experiment were analyzed using the analysis of variance procedure. The predictive models were developed for each range of lift using a stepwise multiple linear regression technique. The models to predict lifting capacity of an individual were validated using three additional subjects. It was concluded that the models can reasonably predict lifting capacity based on the steady state of V02 and heart rate responses achieved during a 30 minute constant-load validation experiment. The predicted lifting capacity was also well within the 95th percentile of published lifting capacity norms. It was also concluded that the AT values were discretely related to the active muscle mass utilized in performing a physical task.Item Lifting capacity determination as a function of task variables(Texas Tech University, 1983-08) Bakken, Gary MaynardNot availableItem Modelling isokinetic strength of the upper extremity(Texas Tech University, 1983-12) Imrhan, Sheik NNot availableItem Predicting oxygen consumption from pulmonary ventilation under low to moderate work loads(Texas Tech University, 1982-08) Calisto, George WNot availableItem Prediction of acceptable lift capacity(Texas Tech University, 1972-12) McDaniel, Joe WileyNot availableItem Prediction of endurance time limit for muscular work under alternating work load conditions(Texas Tech University, 1973-05) Deivanayagam, SubramaniamNot availableItem Psychophysical capacity modeling of individual and combined manual materials handling activities(Texas Tech University, 1984-08) Jiang, Bernard Chen-chunMost psychophysical studies in the field of MMH involve only with single MMH activities, i.e., lifting, lowering, carrying, holding, pushing, or pulling. The combination of two or more activities (e.g., lifting a box, then carrying the box; or carrying a box, then lowering the box) has never been examined. These kinds of combined activities are prevalent in industry and our daily life. The objectives of this study were: 1) To develop models for both individual and combined MMH activities, and 2) To determine the relationship between individual and combined MMH activities. Three types of strength tests (isometric, isokinetic, and isoinertial) using four testing machines (static strength testing machine, Mini-Gym, Cybex, and incremental weight lifting machine) were conducted using 12 male subjects. The capacities for four individual MMH activities and three combined MMH activities were tested psychophysically under three frequency conditions: one time maximum, one handling per minute, and six handlings per minute. In all experimental conditions, the psychophysically determined capacities were the maximum acceptable workloads for a one hour work periods. As a result the mean capacities determined in this study were higher than those reported for eight hour work periods. Second order polynomial regression models for individual MMH capacities were developed using isoinertial 6 foot maximum strength or static back strength. Combined MMH capacities models were developed using the following three methods: a limiting individual MMH capacity, isoinertial 6 foot maximum strength, and fuzzy sets theory. The advantages and disadvantages of different models were compared. The isoinertial 6 foot maximum lift strength was selected because it was a simple, economical, easily applied, and representative test. The models developed in this study provide information about the relationship between a person's strength and his capacity for MMH activities, and about the relationship between individual and combined MMH activities.Item The quantification on human effort and motion for the upper limbs by means of an Exoskeletal Kinematometer(Texas Tech University, 1967-08) Ramsey, Jerry D.The primary purpose of this investigation was to develop instrumentation and computational procedures for the quantification of human effort involved in three dimensional planar movement of the upper limbs, and to evaluate these quantitative measures. A device for monitoring the kinomatic motion of the upper limbs, the Exoskcletal Kinematometer, was developed to provide instantaneous angular displacement data. This device consists of a shoulder mount,, two arm mounts upon which are fastened linkages that follow the arm movement, and potentiometers which measure the angular displacement at the joints of rotation. The angular displacement data served as input to a series of computational procedures which were developed to evaluate various mechanical measures of human effort. The specific measures of interest were: 1. The velocity and acceleration at the center of mass of each arm segment, 2. The changes in mechanical energy of the entire arm system, 3. The force and torque at each arm joint, and 4. The linear and angular impulse at each arm joint. These mechanical indices of effort were determined for each of four subjects under various experimental levels of weight carried, distance moved, angle of abduction, and task duration. Three levels of weight (0, .4, and .8 kilograms), three angles of abduction (0, 20, and 40 degrees), two distances (10 and 20 centimeters), and three durations (0, 2, and 4 minutes) were selected as important parameters found in many "light" or "bench-work" industrial jobs. In addition to assessing the characteristics of the mechanical indices cited above, these measures were correlated with the physiological measures of the same task as reported in research conducted during a parallel investigation. Within the limits of this study, the findings evolving from this investigation are summarized below. Angular impulse or the torque-time product was determined to be the best single mechanical measure of human effort. Both the total angular impulse, which includes the angular impulse at the shoulder, elbow, and wrist, and the shoulder angular impulse could be supported as equally good measures that show sensitivity to the major experimental variables of this task, i.e., subject, weight, distance, and angle of abduction. The average torque at the shoulder showed high correlation to shoulder angular impulse and as such was a comparable indicator of human effort. Both force and the force-time product of linear impulse appeared to be less desirable measures of human effort because of their insensitivity to the effects of distance and angle. The predictive equations for force and linear impulse contained only the variables of weight and subject's arm mass. The mechanical measures of total energy, maximum velocity at the hand, and maximum acceleration at the hand show reasonable potential as indices of human effort, but are especially influenced by the variables of subject and distance. Substitutions of total body weight for arm volume an CI body height for arm length resulted in only minor losses in accuracy for the predictive equations developed in this analysis. All of the mechanical measures had a higher correlation with the physiological measure of ventilation rate/body surface area than with the measures of heart rate or oxygen consumption. The mechanical measures showed higher correlation with the physiological measures for the dynamic task than for the equivalent static task. The correlations between the mechanical and physiological measures of the task substantiate that total and shoulder angular impulse, shoulder torque, and total mechanical energy are the better of the mechanical indices of human effort.Item The quantification on human effort and motion for the upper limbs by means of an Exoskeletal Kinematometer(Texas Tech University, 1967-08) Ramsey, Jerry D.The primary purpose of this investigation was to develop instrumentation and computational procedures for the quantification of human effort involved in three dimensional planar movement of the upper limbs, and to evaluate these quantitative measures. A device for monitoring the kinematic motion of the upper limbs, the Exoskeletal Kinematometer, was developed to provide instantaneous angular displacement data. This device consists of a shoulder mount, two arm mounts upon which are fastened linkages that follow the arm movement, and potentiometers which measure the angular displacement at the joints of rotation. The angular displacement data served as input to a series of computational procedures which were developed to evaluate various mechanical measures of human effort. The specific measures of interest were: 1. The velocity and acceleration at the center of mass of each arm segment, 2. The changes in mechanical energy of the entire arm system, 3. The force and torque at each arm joint, and 4. The linear and angular impulse at each arm joint. These mechanical indices of effort were determined for each of four subjects under various experimental levels of weight carried, distance moved, angle of abduction, and task duration. Three levels of weight (0, .4, and .8 kilograms), three angles of abduction (0, 20, and 40 degrees), two distances (10 and 20 centimeters), and three durations (0, 2, and 4 minutes) were selected as important parameters found in many "light" or "bench-work" industrial jobs. In addition to assessing the characteristics of the mechanical indices cited above, these measures were correlated with the physiological measures of the same task as reported in research conducted during a parallel investigation. Within the limits of this study, the findings evolving from this investigation are summarized below. Angular impulse or the torque-time product, was determined to be the best single mechanical measure of human effort. Both the total angular impulse, which includes the angular impulse at the shoulder, elbow, and wrist, and the shoulder angular impulse could be supported as equally good measures that show sensitivity to the major experimental variables of this task, i.e., subject, weight, distance, and angle of abduction. The average torque at the shoulder showed high correlation to shoulder angular impulse and as such was a comparable indicator of human effort. Both force and the force-time product of linear impulse appeared to be less desirable measures of human effort because of their insensitivity to the effects of distance and angle. The predictive equations for force and linear impulse contained only the variables of weight and subject's arm mass. The mechanical measures of total energy, maximum velocity at the hand, and maximum acceleration at the hand show reasonable potential as indices of human effort, but are especially influenced by the variables of subject and distance. Substitutions of total body weight for arm volume and body height for arm length resulted in only minor losses in accuracy for the predictive equations developed in this analysis. All of the mechanical measures had a higher correlation with the physiological measure of ventilation rate/body surface area than with the measures of heart rate or oxygen consumption. The mechanical measures showed higher correlation with the physiological measures for the dynamic task than for the equivalent static task. The correlations between the mechanical and physiological measures of the task substantiate that total and shoulder angular impulse, shoulder torque, and total mechanical energy are the better of the mechanical indices of human effort.