Thesis (doctoral)--Technische Universiteit Delft, 2004. / Includes bibliographical references.

Thesis (doctoral)--Technische Universiteit Delft, 2004. / Includes bibliographical references.

Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 150-153).

Made available in DSpace on 2014-10-09T12:25:05Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:18Z (GMT). No. of bitstreams: 1 01176.pdf: 7555632 bytes, checksum: 3bb75a619eea080ca949cb9d1b23c80c (MD5) / Tese (Doutoramento) / IEA/T / Universidade Estadual de Campinas - UNICAMP

Made available in DSpace on 2014-10-09T12:25:05Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:18Z (GMT). No. of bitstreams: 1 01176.pdf: 7555632 bytes, checksum: 3bb75a619eea080ca949cb9d1b23c80c (MD5) / Tese (Doutoramento) / IEA/T / Universidade Estadual de Campinas - UNICAMP

Seven alkyl substituted methyl cyclopropanecarboxylates having an alkyl group on C-2 cis to the ester group have been found to rearrange thermally to their corresponding if, [formula omitted] esters at temperatures ranging from 240° to 300° . The corresponding trans isomers are unaffected under identical reaction conditions. It is proposed that the rearrangement takes place by an intramolecular 1,5-hydrogen transfer via a six-membered cyclic transition state. The kinetics for these reactions have been studied and show first-order plots which are linear to 70% reaction. The heat of activation [formula omitted] was found to be between 25 to 38 kcal/ mole and the entropy of activation [formula omitted] was found to be between - 8 and -37 eu from measurements made over a 20° range. This and other information fully support a cyclic hydrogen transfer mechanism. Four methyl cis-2-pentenoates have been found to undergo both geometric and positional thermal isomerizations to yield equilibrium mixtures of 2- and 3-pentenoates at temperatures ranging from 240° to 300°. The 3-pentenoates produced from the corresponding trans-2-pentenoates were found to be formed via the cis - 2-pentenoate3. Studies using β-isopropylacrylate and methacrylate showed that the rate of positional isomerization was much faster than that of geometric isomerization. For these systems it was therefore possible to study the kinetics of the positional isomerism in the absence of competing geometric isomerization, The kinetic data provided first-order plots. The heat of activation [formula omitted] was found to be between 18 and 38 kcal/mole and the entropy of activation [formula omitted] was found to be between -8 to -50 eu. An intramolecular 1,5-hydrogen transfer mechanism involving a six-membered cyclic transition state similar to that for the cyclopropane series is indicated and is suggested to be the general mechanism for conversion of [formula omitted] esters to [formula omitted] esters. The series of 2-alkylcyclopropanes have been prepared by the decomposition of the corresponding pyrazoline3. Some of these pyrazolines have been newly synthesized for this work and include [formula omitted] esters required for this research. Several, however, have also been synthesized by the modified Wittig reaction. / Science, Faculty of / Chemistry, Department of / Graduate

As newer and more powerful technologies emerge in the market, the desire for compactness and aesthetics drive designers to aggressive new heights. The trend of technology is quite simply to deliver high-speed designs that pack more power while seeing reduction in form factor for ease of use at the consumer level. This presents new challenges with reliability, cost, and ultimately what the consumer strives for: performance. It is inevitable for a small compact size device, such as a smartphone or wireless repeater, to face heating issues when packing large amounts of power. The goal of this thesis is to characterize an in-market device’s thermal behavior and RF performance, and present an alternative design approach that helps improve thermal performance. This solution must not increase the design space or form factor excessively. The proposal utilizes an off-the-shelf solution and predicts performance improvements and degradation as a function of thermal performance. Electro-thermal simulators are used extensively to gauge the behavior and flow of heat within a gallium nitride device, and used as a baseline for comparison. Two modified approaches are presented and declared to be more efficient and reliable than the baseline. The design approaches comply with the industry standards of minimizing size and show a clear improvement in thermal behavior that can be utilized for any single device approach. The research is focused under similar power and biasing conditions so that designers can effectively implement a simple plug and play approach whenever the device under test is at risk of violating temperature limits and/or if performance degradation is observed under a variety of operating conditions.

Channel catfish (Ictalurus punctatus) are important to aquaculture and natural ecosystems, however little is known regarding effects of high summer temperatures, which are predicted to increase with climate change. Therefore, two studies were conducted to examine physiological effects of high temperatures on juvenile channel catfish. The first examined effects of three cycling thermal regimes (23-27°C, 27-31°C, and 31-35°C) characteristic of culture environments in Mississippi on growth, food consumption, feed conversion ratio, specific growth rate, and activity. The second study measured active and resting metabolic rates and swimming endurance at constant temperatures (27, 31, and 35°C). The best growth and feed conversion occurred at 27-31°C and activity was greatest at 31-35°C. Active metabolism and swimming endurance decreased at 35°C. These results indicate high summer temperatures reduce food consumption, increase activity, impair metabolism and endurance, and therefore present challenges to the culture and management of channel catfish.

No description available.

Note: