The first objective of this thesis was to assess the effect of casting orientation on bond strength in pretensioned prestressed concrete members. The "top strand effect" was evaluated through transfer and development length tests of prestressed concrete beams. Eight beams were cast with normal orientation, while four beams were cast with inverted orientation so that a significant depth of fresh concrete was placed below prestressing strands. Discrete transfer lengths were determined at the ends of each beam by measuring concrete surface strains. Inverted casting orientation caused an average 70 percent increase in transfer length. Some transfer lengths in beams with inverted casting orientation exceed current ACI and AASHTO code provisions. All measured transfer lengths were less than 90 strand diameters (45 in. for 0.5 in. diameter strands). Ranges of development length were determined through iterative load testing. The top strand effect on development length was more qualitative than quantitative. Ranges of development length in normal beams were conservatively less than code provisions. Ranges of development length in beams with inverted casting orientation were much closer to and sometimes exceeded code provisions. It is recommended that ACI and AASHTO code provisions for the development length of prestressing strand be modified to include the same magnification factors that are specified for the development length of deformed bars with twelve or more inches of fresh concrete placed below. The second objective of this thesis was to compare experimentally measured prestress losses to theoretical calculations. Theoretical prestress losses were calculated according to PCI and AASHTO Refined methods. These methods produced similar results. Prestress losses were experimentally measured by vibrating wire gages and flexural load testing. Vibrating wire gages were used to monitor internal concrete strains. Two methods were used to reduce vibrating wire gage data: an upper/lower bound method and a basic method. The upper/lower bound method produced distorted data that was unreasonable in some cases. The basic method was more reasonable, but resulted in some prestress loss measurements that were greater than theoretical predictions. Flexural load testing was used to back calculate prestress losses from crack initiation and crack reopening loads. Prestress losses measured by crack initiation loads were generally greater than theoretical values. Losses measured by crack reopening loads were distorted. The distortion was attributed to difficulty in isolation of the correct crack reopening load. Large measurements of prestress losses by the basic vibrating wire gage and crack initiation methods suggested that losses occurred between the time when concrete was poured and prestress transfer occurred. Such losses are not accounted for in current code provisions. More research is recommended to determine the magnitude of these additional losses and their effect on design. / Master of Science

No description available.

No description available.

Environmental conditions can lead to mercury accumulations in fish that are highly variability among spatially close lakes in Ontario, Canada. Mercury methylation caused by sulfate reduction can influence total mercury concentrations in fish (THgfish). Kahshe and Mountain lakes were chosen to assess temporal trends of THgfish and using paleolimnological tools described the lake environment in terms of total mercury (THgsed), total sulfur (TSsed), chromium-reducible sulfur (CRSsed), and chrysophyte-inferred lake-water pH (CI-pH). THgfish were standardized by length (LS-THgfish) to identify trends and make comparisons with archived fish from the Royal Ontario Museum. In Kahshe Lake, LS-THgfish for 30-cm smallmouth bass and 40-cm walleye displayed peak concentrations in the early 1980s (0.74 +/- 0.17 µg/g d.w; n=41 and 1.40 +/- 0.42 µg/g d.w; n=16, respectively) with clear declines starting in 1999 (0.33 µg/g d.w +/- 0.13, n=12). At Mountain Lake, LS-THgfish in smallmouth bass (0.31 – 0.45 µg/g) and walleye (0.30 – 0.49 µg/g) were low and stable through the period of observation. Peak concentrations at Kahshe Lake were over 300% higher than the 1926 archival sample (0.22 µg/g d.w, 22.1 cm total length), while the 1948 Mountain Lake sample (0.28 µg/g, 24.4 cm total length) is consistent with modern concentrations. As expected from LS-THgfish , THgsed was higher in Kahshe Lake, although enrichment was seen at both sites. Temporal trends for TSsed and CRSsed diverged with enrichment in Kahshe Lake and depletion in Mountain Lake. CI-pH showed minimal temporal changes. Although trends of CRSsed indicate sulfate is processed differently among the lakes, geochronology highlighted a consistent spatio-temporal relationship between THgfish and CRSsed. This strongly supports a relationship between sulfate reduction rates and Hg methylation, independent of THgsed and pH. Therefore, if THgfish is used as an indicator of aquatic health CRSsed may be a useful tool for rapid assessment. / Thesis (Master, Biology) -- Queen's University, 2013-01-11 15:48:02.718

No description available.

by Agnes Kam-Kwan Chow Gardner. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 136-144.

SNO+ is a multipurpose neutrino experiment located at SNOLAB. Its key purpose is investigating the neutrinoless double beta decay of 130Te, amongst other physics goals such as solar and reactor neutrino oscillations. The success of the experiment depends on the understanding of the optical properties of the detection materials, as well as a good understanding of potential background contributions. The calibration system used to study the Rayleigh scattering properties of the detector is presented and methods to model the system in Monte Carlo simulations based on commissioning run data are introduced. Furthermore, the analysis of the scattering length in a water-filled detector is described and demonstrated on a fake water-fill data set with an accuracy of the measured scattering length scaling factor of 1:1 %. The evaluation of the systematic uncertainties is presented. The background contributions originating from the 238U and 232Th decay chains during early SNO+ run phases are constrained using 214Bi214Po and 212Bi212Po delayed coincidences. The methods to identify these coincidences are presented and the challenges to apply them to an intermediate partial water-scintillator phase are discussed. It is shown that for the current target background rates the 238U and 232Th chain contents can be determined with an uncertainty of 4:1% and 27:6%.

by Chan Lai Yin, Simon. / "December 1998." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Objective: The objective of this study is to develop a national assessment of the length of stay (LOS), total costs, and in-hospital mortality among patients with chronic obstructive pulmonary disease (COPD), using retrospective data derived from Nationwide Inpatient Sample (NIS) of the Healthcare Cost and Utilization Project (HCUP). / Mylan School of Pharmacy and the Graduate School of Pharmaceutical Sciences; / Pharmacy Administration / MS; / Thesis;

Truckload shipments constitute a significant portion of the freight transportation industry. In recent years, truckload industry is facing a serious problem of high driver turn over rate. In this research, we present a mathematical model for multi-zone dispatching method to solve this issue. Multi-zone dispatching is a method in which a service area is divided into many zones. Truckload within a zone is carried by local drivers and the truckload between zones is carried by lane drivers. Apart from reducing the driver tour length to a desirable level, the model for multi-zone also contains some unique constraints to address some issues from the perspectives of the company and the customer. The binary integer program is solved by exact methods. As the problem size increases, exact methods fail quickly. Hence, a construction heuristic within tabu search framework is developed to solve the model. Analysis of various parameters concerned is provided to gain better insights of varied aspects of the problem. Computational results for analysis of parameters and comparison of exact and heuristic methods are provided.