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The aim of this study is to develop a combined experimental and analytical framework for accelerated lifetime estimates of semi-crystalline plastic pipes which is sensitive to changes in structure, orientation, and morphology introduced by processing conditions. To accomplish this task, high-density polyethylene (HDPE) is chosen as the exemplary base material. As a new accelerated test protocol, several characterization tests were planned and conducted on as-manufactured HDPE pipe segments. Custom fixtures are designed and developed to admit uniaxial characterization tests. The yield behavior of the material was modeled using two hydrostatic pressure modified Eyring equations in parallel to describe the characterization test data collected in axial tension and compression. Subsequently, creep rupture failure of the pipes under hydrostatic pressure is predicted using the model. The model predictions are validated using the experimental creep rupture failure data collected from internal pressurization of pipes using a custom-designed, fully automatic test system. The results indicate that the method allows the prediction of pipe service lifetimes in excess of 50 years using experiments conducted over approximately 10 days instead of the traditional 13 months. The analytical model is joined with a commercial finite element package to allow simulations including different thermal-mechanical loading conditions as well as complicated geometries. The numerical model is validated using the characterization test data at different temperatures and deformation rates. The results suggest that the long-term performance of the pipe is dominated by the plastic behavior of the material and its viscoelastic response is found to play an insignificant role in this manner. Because of the potential role of residual stresses on the long-term behavior, the residual stress across the wall thickness is measured for three geometrically different HDPE pipes. As expected, the magnitude of tensile and compressive residual stresses are found to be greater in pipes with thicker walls. The effect of the residual stress on the long-term performance of the pipes is investigated by including the residual stress measurements into the numerical simulations. The residual stress slightly accelerates the failure process; however, for the pipe geometries examined, this acceleration is insignificant. / Doctor of Philosophy / The use of plastic pipes to carry liquids and gases has greatly increased in recent decades, primarily because of their moderate costs, long service lifetimes, and corrosion resistance compared with materials such as corrugated steel and ductile iron. Before these pipes can be effectively used, however, designers need the capability to quickly predict the service lifetime so that they can choose the best plastic material and pipe design for a specific application. This capability also allows manufacturers to modify materials to improve performance. The aim of this study is to develop a combination of experiments and models to quickly predict the service lifetime of plastic pipes. High-density polyethylene (HDPE) was chosen as the plastic material on which the model was developed. Several characterization tests are planned and conducted on as-manufactured HDPE pipe segments. The yielding behavior of the material is modeled and the lifetime predictions are evaluated. The predictions are validated by experimental data captured during pipe burst tests conducted in the lab. The results indicate that the method allows the accurate prediction of pipe service lifetimes in excess of 50 years using experiments conducted over approximately 10 days instead of the traditional 13 months, resulting in significant savings in time (and consequently costs) and making it possible to introduce new materials into production more rapidly.

This thesis project is complex because of its crystalline form. It is ordered through structural hierarchy and modularity. The presence of both complexity and order gives articulation to all scales of the project, allows for variety without chaos, and repetition without monotony. All of these characteristics are essential for the program of a high-rise residential building that accommodates 1,500 people. / Master of Architecture

The frequent use of high-density polyethylene pipes over the last decades has been possible because these pipes are lightweight, corrosion resistant, unlikely to have leaks, and are low cost. The chain structure of the polymer, the extrusion and cooling conditions, the resulting morphology and the ambient conditions all play an important role in the pipe's performance. A new generation of high density polyethylene resins has improved the performance of pipes, but brought new challenges to their testing and characterization. There is a need to understand the rheological behavior of the resins, their processing, and their associated properties in a finished pipe. The rheological behavior of the resins was studied to characterize the effect of high molecular weight tails in a bimodal molecular weight distribution. The use of cone-and-plate and parallel-plate geometries in a rheometer provided simple flow that characterized the steady and dynamical response of the polymer melts. The rheological measurements detected differences in the resins: the resin with higher molecular weight tail showed increased zero shear-rate viscosity, a much slower relaxation of stresses and a resin that more readily deviates from linear viscoelastic behavior. The rheology of the resins allowed modeling their flow through different extrusion dies. The flow channels for pipe dies are thick, so velocities and shear rates are low. Using a different die had a larger impact in shear rates and stresses compared to using different resins. The resin with higher molecular weight shows much higher shear stresses for the same die and temperature, which makes processing harder. The flow of a fluid through a pipe causes constant stress, which at long enough times is one the reasons for pipe failure. Tests that characterize the service lifetime of pipes take long times and are expensive. Dynamical mechanical analysis allows characterizing the viscoelastic properties of the pipe and creep testing confirms that shift factors work for viscoelastic properties measured inde-pendently. For the characterized pipes, one hour of testing at 80 °C is equivalent to a month of test-ing at 25 °C. This works characterizes pipes made from two resins and two different dies. The meas-urements showed that the pipes were statistically the same. / Doctor of Philosophy / The use of high-density polyethylene pipes has thrived over the last decades. This has been possible because these pipes are lightweight, corrosion resistant, unlikely to have leaks, and are low cost. The structure of the polymer and the manufacturing process both affect the pipe's performance. A new generation of high density polyethylene resins has improved the performance of the pipes, but brought new challenges to their testing and characterization. There is a need to understand the flow characteristics of the resins and their properties as a finished pipe. The flow behavior of the polymers in simple geometries gave insights into the polymer's structure. A higher molecular weight resin showed increased resistance to flow and deviated from ideal behavior more readily. These flow characteristics let one model certain aspects of the manufacturing process. Pipe manufacturing is a slow process because of the high resistance to flow of the polymer. Changing the processing equipment, and to a minor degree changing the resins, had an important impact in the manufacturing process. The tests that characterize the service lifetime of pipes take long times and are expensive. When pipes have fluids flowing at high pressures, it takes decades for them to fail. There are viscoelastic tests that allow much quicker characterization of pipes and help predict their long term behavior. This works characterizes pipes made from two resins and two different dies. This works characterizes pipes made from two resins and two different dies. The measurements showed that the pipes were statistically the same.

Thesis (Ph. D.)--University of Sydney, 2009. / Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Pathology, Faculty of Medicine. Title from title screen (viewed Sept. 30, 2009) Includes bibliography. Also available in print form.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Space and Missile Systems Center at Vandenberg AFB has integrated ID-1 high bit rate helical scan digital recorders into the ground based and mobile telemetry receiving and processing facilities. The systems are used for recording higher bit rates than those available with the current IRIG standard longitudinal wideband and double density instrumentation magnetic tape recorder/reproducers. In addition to the 400 Mbps digital recorders, the systems consist of high-speed multiplexer/ demultiplexers and multi-channel bit synchronizers for recording numerous telemetry data links and sources on a single recorder. This paper describes the system configurations and compares recording capabilities with those of the previous generation instrumentation magnetic tape recorder/reproducers.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / Magnetic tape is the primary medium used to capture and store unprocessed data from remote sensing satellites. Recent advances in digital cassette recording technology have resulted in the introduction of a range of data recorders which are equally at home working alongside conventional recorders or as part of more advanced data capture strategies. This paper shows how users are taking advantage of the convenience, economy and efficiency of this new generation of cassette-based equipment in a range of practical applications.

Two studies were conducted to determine how HDL cholesteryl ester and apoprotein catabolism might contribute to the observed hypercholesterolemia of copper-deficient rats. Weanling male Sprague-Dawley rats were divided into two dietary treatments; copper-adequate (control, 5-7 mg Cu/kg diet) and copper-deficient (0.6-0.8 mg Cu/kg diet). Deionized water and diet were provided ad libitum. Dietary copper deficiency resulted in enlarged intravascular pools of HDL cholesteryl esters and total protein. HDL were isolated from rats of both treatment groups, radiolabeled, and injected into animals of the respective groups. In Study I, HDL apoproteins were labeled by iodination, whereas HDL in Study II were doubly labeled by additionally incorporating into the particle core [³H]cholesteryl linoleyl ether, which served as a nondegradable analog of HDL cholesteryl ester. At specific time intervals up to 12 hours after injection, blood and tissue samples were removed and analyzed for radioactivity. Plasma disappearance curves indicated that HDL cholesteryl esters were preferentially catabolized 1.6-fold faster than HDL protein in controls and 2.5-fold faster in copper-deficient animals. Clearance of individual apoproteins did not occur at significantly different rates in either treatment group. Absolute mass removal of HDL cholesteryl ester and total protein from the plasma was significantly increased in copper-deficient rats. Virtually all of the increased removal of HDL cholesteryl ester was attributed to the liver, whereas most of the increased uptake of HDL protein was attributed to the bulk tissues and not the liver. Since previous studies indicate that copper deficiency may not result in increased cholesterol excretion, these data suggest that cholesteryl esters delivered to the liver of copper-deficient rats are possibly reassembled into new HDL particles at an increased rate. The observed hypercholesterolemia in this animal model, then, appears to be the result of an imbalance in the net flux of cholesterol between the tissues and the plasma.

M.Phil. / Numerous studies have demonstrated the favourable effects of aerobic training on blood lipid profiles. However, few studies have generated conclusive data on the effects of dynamic resistance training (DRT) on blood lipid profiles. In order to evaluate the effect of DRT on lipoprotein-lipid profiles, a group of 28 sedentary but healthy males (mean age 28 years and 7 months) were matched and randomly assigned into a control/non-exercising (n = 15) or an experimental (n = 13) group. To control for variations in lipoprotein-lipid profiles, the present investigation recorded dietary intake and smoking behaviour in an attempt to account for any changes in lipoprotein-lipid profiles over the eight-week period. The experimental group (EG) exercised using DRT for a period of eight weeks and was monitored for changes in lipoprotein-lipid profiles. The control group (CG) took part in no structured exercise throughout the eight-week period. The experimental training programme consisted of nine exercises (dumbbell (D/B) shoulder shrugs, D/B lateral shoulder raises, seated chest press, latissimus dorsi pulldowns, seated pulley rows, biceps curls, triceps extensions, crunchies and unilateral leg press). These exercises were performed at 60% of one repetition maximum (1-RM) and were performed three times per week on non-consecutive days. Serum was analyzed for total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). In addition to this, the TC: HDL-C and LDL-C: HDL-C ratios were calculated. The Independent t-Test and the Paired t-Test were utilized to determine the significance (at a 95% confidence level (p ¡Ü 0.05)) of the lipoprotein-lipid profile changes from pre- to post-test. These student t-Tests demonstrated no statistically significant changes in TC, TG, LDL-C, HDL-C, TC: HDL-C ratios and LDL-C: HDL-C ratios in the EG. However, the present investigation did demonstrate the following changes: a 0.50% decrease in TC, a 1.74% increase in TG, a 2.95% decrease in LDL-C, a 4.61% increase in HDL-C, a 4.12% decrease in the TC: HDL-C ratio and a 5.96% decrease in the LDL-C: HDL-C ratio. The lack of statistically significant changes in the individual lipoprotein-lipid parameters could not have been affected by diet, cigarettes smoked daily, aerobic fitness and/or body mass, since these parameters did not change significantly from pre- to post-test. Specifically, both the EG and CG demonstrated no statistically significant changes in intake in total calories consumed, carbohydrates, proteins, fats (monounsaturated, polyunsaturated and saturated fatty acids), cholesterol and fibre. Although the present investigation findings suggest that this study¡¯s eight-week combination of dose, workload, number of repetitions and order and number of exercises may not have been sufficient to elicit significant improvements in lipoprotein-lipid parameters in this population of sedentary but healthy males, it is the opinion of the author that DRT should be included with aerobic modes of exercise. DRT should be used in conjunction with aerobic modes of exercise for its additional benefits. Such additional benefits include inter alia: increased strength, increased lean tissue mass, increased maintenance of metabolically active tissue in the elderly and increased muscle control. / Prof. J.M. Loots Mr. L. Lategan