The thesis Is concerned with the development of a separately excited DC machine In which gate turn-off thyristor devices with their associated firing and protective circuits are used to provide the static commutation of armature coil current. The developed machine has Its armature winding with 24 tapping points located on the stator and Interconnected In "Lop" configuration. The Initiation of the conduction periods of armature switching devices Is defined by a digital control logic circuit. In conjunction with an Incremental rotary encoder which provides the necessary feedback Information relating to shaft speed and shaft angular position. This Is arranged such that, under normal running conditions of the machine, the axis of the radial field of the armature winding maintains the normal space-quadrature relationship with that of the main field winding, giving the optimal torque angle of 000. Provision Is made, however, within the digital control circuit for controlled departure of the armature switch tapping points from the quadrature axis positions, and the effect of this, In Improving commutation Is Investigated. The effect of Interpoles Is also explored. On the basis of the analysis carried out, a proposal Is made for the future development of the machine employing a reduced number of armature switching devices without the need for Interpole windings.

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Ur svårigheterna att förklara företags kapitalstruktur och hur den är förknippad med olika risker för olika ägartyper, är syftet att undersöka vilken av Trade-off-teorin och Pecking order-teorin som bäst kan förklara skuldsättningen hos svenska familjeägda företag på Stockholmsbörsen. Med hjälp av en modell för respektive teori har vi genomfört regressionsanalyser för att besvara vårt syfte. Med grund i tidigare forskning kring familjeägda företag och teoriernas grundläggande synsätt på förändring i skuldsättning, har studien utgått från hypotesen att familjeägda företag i högre utsträckning kommer att finansiera sig med internt genererade medel än extern belåning, vilket ligger i linje med Pecking order-teorin. Studien utgår från både finansiell- och ägardata gällande tidsperioden 2004-2013. Resultaten pekar likt hypotesen förutspått mot ett större stöd för Pecking order-teorin hos svenska familjeägda företag. Studiens slutsats är att Pecking order-teorin, i högre utsträckning än Trade-off-teorin, kan förklara skuldsättningen hos svenska familjeägda företag.

Technologies such as horizontal wells and multi-stage hydraulic fracturing have made ultra-low permeability shale and tight gas reservoirs productive but the industry is still on the learning curve when it comes to addressing various production issues. Some of the problems encountered while hydraulically fracturing these reservoirs are the absence of frac barriers, thinner shales and the increased presence of geological hazards. Induced vertical fractures sometimes extend to an underlying aquifer and become a conduit to the well. We have developed a low-concentration, low-viscosity and delayed-crosslink polymeric gel system as a water shutoff agent for hydraulically-fractured tight gas and shale reservoirs, where some fractures might connect to water rich zones. The system also is a significant improvement over traditional flowing gels for fracture water shutoff in conventional reservoirs because of these features. The gel uses high molecular weight hydrolyzed polyacrylamide (HPAM) at low polymer concentrations with a delayed organic crosslinker. This crosslinker is more environmentally benign and provides much longer gelation time and stronger final gels than comparable polymer loadings with chromium carboxylate crosslinkers at higher temperatures. The low viscosity system allows low-pressure extrusion of gelant into the narrow-aperture fractures present in unconventional gas reservoirs. The gelant can be pumped at low pressures due to lower polymer concentrations and delayed gelation point. This allows the potential to seal problem zones that are producing excess water even when the fractures conducting water have very narrow apertures. By impeding water production, the gel system developed here can effectively delay water loading thereby avoiding abandonment or installation of expensive equipment with increased operational costs, thus extending life and reserves of unconventional gas wells.

Compression and information retrieval are two areas of document management that exist separately due to the conflicting methods of achieving their goals. This research examines a mechanism which provides lossless compression and phrase-based browsing and searching of large document collections. The framework for the investigation is an existing off-line dictionary-based compression algorithm. (For complete abstract open document)

Thesis (Ph. D.)--University of Nevada, Reno, 2007. / "May, 2007." Includes bibliographical references. Online version available on the World Wide Web.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2004. / Härtill 6 uppsatser.

Thesis (M.S.)--University of Nevada, Reno, 2005. / "August 2005." Includes bibliographical references (leaves 48-54). Online version available on the World Wide Web.

Thesis (M.S.)--California Polytechnic State University, 2008. / Mode of access: Internet. Title from PDF title page; viewed on March 17, 2009. Major professor: David D. Marshall. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree of Master of Science in Aerospace Engineering." "June 2008." Includes bibliographical references (p. 126-127). Also available on microfiche.

Thesis (M.S.)--University of Nevada, Reno, 2007. / "December, 2007." Includes bibliographical references. Online version available on the World Wide Web.