The retention curve of an incompletely learned avoidance response was investigated, employing rats in a shuttlebox situation. Subjects were given a 15 trial re-learning session 0, 1/2, 1 or 24 hours after original acquisition. Three treatment groups were tested at these intervals: a not-handled group which remained in the shuttlebox during the intersession interval, a handled group which remained in the shuttlebox during the intersession interval, and a group which was returned to a living cage. All treatment groups produced a monotonically decreasing curve as a function of intersession interval. Handling produced a decrement on performance at 0-hour intersession interval; location showed no effect. Results were interpreted in terms of the warm-up decrement and the effects of handling on the arousal of fear. / Thesis / Master of Arts (MA)

In real-word manufacturing environments, finding the right job sequences and their associated schedules when resource, precedence, and timing constraints are imposed is a difficult task. For most practical problems classical scheduling easily leads to an exponential growth in the number of possible schedules. Moreover, a decision time period of hours or even minutes is too long. Good solutions are often needed in real-time. The problem becomes even more complicated if changes, such as new orders or resource breakdowns, occur within the manufacturing system. One approach to overcome the challenges of solving classical scheduling problems is the use of distributed schemes such as agent or holonic-based control architectures. This dissertation presents an innovative control architecture that uses the holonic concept, capable of delivering good solutions when applied in dynamic environments. The general holonic control framework presented in this research has specific characteristics not found in others reported so far. Using a modular approach it takes into account all the categories of hardware and software resources of a manufacturing system. Due to its modularity, the holonic control framework can be used for assigning and scheduling different task types, separately or simultaneously. Thus, it can be used not only for assigning and scheduling transport tasks, but also for finding feasible solutions to the job assignment and scheduling of processing tasks, or to better utilize the auxiliary equipment and devices in a manufacturing system. In the holonic system, under real-time constraints, a feasible schedule for the material handling resources emerges from the combination of individual holon's schedules. Internal evaluation algorithms and coordination mechanisms between the entities in the architecture form the basis for the resultant schedules. The experimental results obtained show a percentage difference between the makespan values obtained using the holonic scheduling approach and the optimal values of under seven percent. Since current control systems in use in industry lack the ability to adapt to dynamic manufacturing environments, the holonic architecture designed and the tests performed in this research could be a part in the effort to build the foundations for the control systems of the next generation manufacturing systems. / Ph. D.

Work-related musculoskeletal disorders (WMSDs) are prevalent among health care workers worldwide and underreporting among nurses may mask the true impact of these injuries. Nursing staff are consistently among the top 10 occupations at risk for experiencing WMSDs and patient-handling tasks are the precipitating event in the majority of back injuries experienced among nursing staff. Existing research has focused on patient-handling issues within long-term care facilities, and identifying physically demanding patient-handling tasks. The first study in this dissertation (Chapter 3) was conducted to determine whether nurses in acute care facilities are exposed to the same hazards as their cohorts in long-term care. The aim was to identify the top 10 patient-handling tasks being conducted and to rank these tasks by perceived physical demand. This two-phase study consisted of a procedural task analysis of patient-handling activities, and a questionnaire to identify the characteristics of the study population and obtain a ranking of physically demanding patient-handling tasks. All nurses providing direct inpatient care were recruited to participate in both phases of this study. Compared to long-term care facilities, in which the majority of tasks have been shown to be associated with performance of ADL tasks, the most frequently observed tasks in the acute care facility were repositioning tasks. Therefore, it is important to determine the patient-handling demands and needs that are unique to each type of healthcare facility. Generalizing across facilities or units may lead to incorrect assumptions and conclusions about physical demands being placed on nurses. A laboratory simulation was used for the second study (Chapter 4). The top four physically demanding patient-handling tasks (taken from Chapter 3) were simulated to determine the effect of an assistive device and assistance from another person. Sixteen nurse volunteers were recruited and provided perceptual responses regarding exertion and injury risk. Nurses perceived that assistance decreased their physical exertion and injury risk; however they consistently perceived exertion to be relatively higher than their injury risk. The aim of the third study (Chapter 5) was to determine the level of agreement between and within different expert groups. Three groups of participants were involved, with different levels of ergonomics expertise (i.e. researchers, consultants, and graduate students). These groups viewed digitized video clips from the laboratory simulation (Chapter 4) and provided ratings of perceived exertion, perceived injury risk and common WMSD risk factors (effort, posture, and speed). The major finding from this study was that poor agreement existed between nurses and the other expert groups (researchers, consultants and students). The current research laid the groundwork for measuring the magnitude of physical exposure to injury risk in the patient-handling environment. The research supports earlier evidence that suggests nurses underreport their discomfort and injury, which, in turn, contributes to increased exposure and risk. This knowledge will enable practitioners to focus interventions and designs on those factors in the work environment that contribute significantly to increased exposure and thereby more effectively reduce WMSD risk. / Ph. D.

A new way of looking at scheduling and lot sizing is proposed by embedding material handling considerations in the determination of optimum delivery policies for a single stage, uniform demand assembly system in a finite horizon. Unit loads are used in place of lots; material handling and container costs are charged; and area and material handling constraints are imposed. A solution procedure based on a delivery period matrix is used to solve the minimization problem. Computational experience is provided. A special case of uniform delivery intervals is taken up and a discussion is given on variance penalty. / M.S.

Yes / This paper presents a simulation study into the characteristics of a vehicle experiencing steering drift under straight line braking. Simulation modelling has been performed using a multi-body dynamics analysis based on a model of an actual vehicle. Front and rear suspension parameters have been modelled as rigid links joined with flexible bushes so as to assess their effect on a vehicle while braking. Suspension geometry and alignment settings, which define characteristic responses such as lateral acceleration, yaw velocity, toe, and caster angles of a vehicle in a transient manoeuvre, are primary to a vehicle¿s directional stability. Any symmetric inconsistencies in these settings will potentially affect a vehicle¿s performance. The findings from this research have increased the understanding of the causes of steering drift during braking conditions.

This thesis identifies various material handling model parameters which must be addressed when using simulation. Operations of six material handling devices (AGVS, AS/RS, conveyors, cranes, fork trucks, and industrial robots) are studied to determine attributes which require modeling consideration. Four simulation software packages (GPSS, PROMODELPC, SIMAN IV, and SLAM II) are analyzed to determine their capabilities for modeling material handling situations. A survey was developed to extract information, from software experts, about each software package under study. Based on this survey, the state-of-the-art in modeling materials handling systems is assessed. / Master of Science

Master of Science

Hay is one of Virginia's important agricultural crops. It ranks third in dollar value, being exceeded in value only by corn and tobacco. The 1948 hay crop was valued at $46,486,000 according to the Virginia Crop Reporting Service (16), and 1,414,000 acres of land were used to produce approximately 1,823,000 tons of hay. As shown by this report, more acres of Virginia's crop land were used to produce hay in 1948 than any other single crop. By using better agronomic practices the hay yield per acre of land used to produce hay has been gradually increased. The climatic conditions found in the southeastern states are among the nation's most favorable for the production of hay, but these same conditions make it almost impossible to cure high quality hay in the field. The average total rainfall for any one month during the hay curing season is not excessive, but the numerous light showers at short intervals make the field curing of hay very difficult. In many instances, hay crops are almost sufficiently field dried for safe storage in the barn when a light shower falls and causes additional hay losses to occur. In 1942 a survey (1) of hay losses was made on 215 farms in nine Southwest Virginia Counties, with the farmers reporting 25% of their crops lost or damaged because of unfavorable weather. In 1948 a survey was made of the hay losses due to weather hazards in all counties of Virginia. The county agents estimated that 31.6% of Virginia's total hay crop was damaged 25%, 15% was damaged 50%, and 4% was a total loss. This report shows that 50.6% of all hay produced in Virginia was damaged 25% or more. Reports from Virginia hay inspectors indicated that only a very small amount of the field cured hay met the requirements for U.S. No. 1 hay. This means that the annual hay losses in Virginia due to weather hazards have been tremendous when it was cured in the field. Agricultural Engineers in cooperation with many organizations have developed barn hay driers as a means of reducing these hay losses. Farmers have been furnished detailed plans and specifications for installing and operating these driers. At the close of the 1948 hay drying season, there were 487 hay driers in operation on Virginia farms. Eighty-three of these systems were installed in 1948. The same survey shows that 456 units were used to dry long hay, 22 baled hay, and 19 chopped hay. Available data (1) shows that barn dried hay will grade from one to two grades better than field dried hay which is harvested from the same field, the only difference being in the method used in curing. The barn dried hay shows a decided advantage over field dried hay when considering the amount of leaves, green color, carotene and protein content retained. The success farmers have obtained by using the forced ventilation method of curing hay has made hay driers very popular. Hay dryers can 7 be used advantageously on many farms that produce hay. This is particularly true when the hay is stored in mows where electric service is available to operate motors. With this system, each mow is considered separately and the air distribution system must be “tailor-made“ to fit the mow. On some farms, the relative location of buildings and fields, availability of electric service, or methods of storing and feeding hay, are such that the typical barn hay dryer is not adaptable. / Master of Science

Master of Science

This study investigated the effectiveness of teaching basic food safety principles by programmed instruction for consumers. A linear-type programmed text was developed and evaluated. The difference between initial behavior and terminal behavior of subjects using the programmed text was assessed in relation to the terminal objectives of the programmed material. The terminal objectives of the programmed material were expressed in a criterion test used as a pretest and post-test. The criterion test and programmed text were administered to 2 groups of consumers consisting of 20 subjects and 17 subjects, respectively. A positive change in scores between the pretest and post-test was significant at the 0.001 level for both groups. The error rate of the programmed text was within the specified 10 per cent level. The maximum time required to complete the programmed text was estimated to be 1 hour. The results obtained indicated that food safety could be taught effectively to consumers through programmed instruction. / Master of Science