Call number: LD2668 .T4 1965 R883 / Master of Science

Depuis la nuit des temps, la matière est connue sous trois états, soient l'état solide, l'état liquide et l'état gazeux. Depuis, de nouveaux états ont été découverts. Les études au sein des laboratoires des professeurs Soldera et Lebel se concentrent sur ces états particuliers. Ils travaillent surtout sur les transitions de phases menant à ces états. Lorsqu'on parle de solide, on fait généralement référence à l'état cristallin, qui est un réseau bien structuré où les interactions à longue portée sont importantes et bien définies. Il existe toutefois une autre forme de solide où le désordre semble régner. Les interactions à longue portée ne sont pas prépondérantes. Il s'agit de l'état vitreux. Le passage de l'état liquide à l'état vitreux est appelé la transition vitreuse, et est caractérisé par une température, T[indice inférieur g] . Les principaux composés menant à l'état vitreux sont les polymères et les verres inorganique [i.e. inorganiques] tels que l'oxyde de silice, très répendus [i.e. répandus] et grandement étudiés. Les verres organiques sont une autre famille de composés qui présentent une phase amorphe stable. Le développement des technologies de pointe a suscité un intérêt pour les verres moléculaires dû à leurs propriétés intéressantes telles que leur structure bien définie et une bonne stabilité thermique. La T[indice inférieur g] détermine le domaine de températures où il peut être utilisé selon l'application recherchée. Les verres moléculaires ont beaucoup de potentiel en industrie, mais ils constituent une famille de matériaux fonctionnels méconnus. S'il reste beaucoup à apprendre sur les polymères, tout reste à apprendre sur les verres moléculaires. Il y a moins d'une vingtaine d'années que la triazine a commencé à être étudiée comme précurseur de verres moléculaires. La synthèse de verres efficaces peut être fastidieuse et ne procure pas nécessairement les propriétés recherchées. C'est pour cette raison que cette étude a été entreprise. L'idée de base de ce travail vise à trouver des moyens de prédire la T[indice inférieur g] , la première propriété recherchée, et ce, en se basant seulement sur la structure moléculaire. Pour relever ce défi, la voie considérée est la simulation atomistique faisant appel à un modèle tout-atome. Cette méthode a déjà fait ses preuves dans l'étude de la T[indice inférieur g] de polymères vinyliques, par les travaux du groupe du professeur Soldera. Bien que le principe de base soit resté le même, il [a] fallu apporter de légères modifications quant à son application aux systèmes étudiés. Suite à la paramétrisation du champ de forces utilisé, pcff, la simulation d'une quinzaine de molécules dont la T[indice inférieur g] expérimentale est connue a pu être conduite. Les résultats obtenus ont permis de révéler une linéarité entre les valeurs obtenues par simulation et les données expérimentales. Il est important de noter que la méthode a permis de distinguer les différents verres moléculaires étudiés bien que la seule différence entre les composés soit le groupement fonctionnel. Cet accord a permis d'effectuer diverses analyses au niveau moléculaire afin de mieux comprendre les facteurs qui influencent les valeurs de T[indice inférieur g] , et donc in fine d'apporter des indices pour une meilleure compréhension de cette transition fort complexe. Les fonctions de distribution radiale ainsi que la rotation des différentes fonctionnalités par rapport au noyau commun triazine, ont ainsi été regardées.

The focus of the thesis is on how school leavers deal with the flood of information, advice and expectations that are directed towards them at a structurally induced turning point in their lives. With a departure point in Giddens’ claim that people select and interpret information on their own terms as a means of preserving coherent narratives of self-identity, stories of information seeking were examined as a means of gaining insight into how young people living in late modernity face its tensions and dilemmas in the ways in which they seek and use information. The theoretical framework of the study draws on Schutz’ ideas concerning the lifeworld and the social distribution of knowledge, on Bourdieu’s concept of habitus as well as on Giddens’ conceptualisation of the forming of self-identity in late modernity.The study is based on qualitative research interviews with twenty one school leavers during their last year at school and on a minor discourse oriented study of a selection of the information produced by major actors in the careers guidance system. Empirically, accounts of young people’s experiences of their information related activities in relation to study and occupational choice were examined using phenomenological narrative analysis. These accounts were set in relation to discourses in Swedish society concerning work and education.Four approaches to information seeking emerged from participants’ accounts: 1) They use information seeking as a tool in making connections between educational interests and the future labour market 2) They use information seeking both as a tool in finding pathways to occupations and as a means of orienting within an occupational domain 3) Study and career information seeking is put ‘on hold’, and information seeking is associated with planning extended transitions, and 4) Study and career information seeking is avoided as potentially threatening or as meaningless. By considering how approaches are related to the ‘new career’ discourse that comes to expression in study and career related information the study gives insights into the meaning of information for, and of its accessibility to, young people. A greater focus on the development of an information literacy is suggested as a means of better supporting young people in the process of making study and career decisions. / Akademisk avhandling som med tillstånd av samhällsvetenskapliga fakulteten vid Göteborgs universitet för vinnande av doktorsexamen framläggs till offentlig granskning kl. 13.00 fredagen den 5 juni 2009 i sal M404, Högskolan i Borås.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The White Sands Telemetry Data Center (TDC) is moving to a new home. The TDC, along with various range functions, is moving to the new J. W. Cox Range Control Center (CRCC). The CRCC is under construction and will replace the present control center. Construction of the new CRCC and the resulting move was prompted by the presence of asbestos in the present Range Control Center (RCC). The CRCC construction will be completed in September 1999 at which time the communications backbone will be installed. (Estimated time to complete the installation is nine months.) In early 2000, White Sands will begin transition of the TDC and other commodity functions to the CRCC. The transition must not interrupt normal support to range customers and will result in the consolidation of all range control functions. The new CRCC was designed to meet current and future mission requirements and will contain the latest in backbone network design and functionality for the range customer. The CRCC is the single point of control for all missions conducted on the 3700 square mile range. The Telemetry Data Center will be moved in two parts into the new CRCC. This will allow us to run parallel operations with the old RCC until the CRCC is proven reliable and minimize overall downtime. Associated telemetry fiber optics, microwave communications and field data relay sites will be upgraded and moved at the same time. Since the TDC is so tightly dependent upon data input from both fiber optics and microwave communications inputs, a cohesive move is critical to the overall success of the transition. This paper also provides an overview of the CRCC design, commodity transition, and lessons learned.

Extreme conditions allow us to reveal unusual material properties. At the same time an experimental approach is di-cult under such conditions. Capabilities of a theoretical approach based on simplied models are limited. This explainsa wide application of computer simulations at extreme conditions. My thesis is concerned with computer simulations undersuch a conditions. I address such problems as melting, solidsolid phase transitions, shockwave impact on material properties and chemical reactions under extreme conditions. We addressed these problems to facilitate simulations of phase transitions to provide some interpretation of experimental data andexplain enigmatic phenomena in interior of the Earth. / <p>QC 20160615</p>

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / The Integrated Monitoring and Control COTS System (IMACCS) was developed as a proof-of-concept to show that commercial off-the-shelf (COTS) products could be integrated to provide spacecraft ground support faster and cheaper than current practices. A key component of IMACCS is the Altair Mission Control System (AMCS), one of several commercial packages available for satellite command and control. It is distinguished from otherwise similar tools by its implementation of Finite State Modeling as part of its expert system capability. Using the Finite State Modeling and State Transition capabilities of the ALTAIR Mission Control System (AMCS), IMACCS was enhanced to provide automated monitoring, routine pass support, anomaly resolution, and emergency "lights on again" response. Orbit determination and production of typical flight dynamics products, such as acquisition times and vectors, have also been automated.

Thesis (MScEng) -- Stellenbosch University , 2001. / ENGLISH ABSTRACT: The electrochemical analysis of selected metal ions with the newly biodegradable chelating agents, lminodisuccinic acid (IDS) and Polyaspartic acid (PASP) was performed by cyclic voltammetry using a thin mercury film glassy carbon microelectrode. IDS and PASP are of interest from an environmental perspective. They were introduced as alternatives to chelants and dispersants. The thermodynamic stability constants of these selected metal complexes were determined by cyclic voltammetry (CV). A comparison with similar data obtained using potentiometric methods shows a good correlation between the two methods. This reaffirms that CV is a useful and facile means for evaluating metal-ligand complex thermodynamic data. Furthermore, our results were used to validate the predicted models obtained using an Equilibrium Speciation model JESS program. Capillary Electrophoresis (CE) was used to separate metal-IDS and metal-PASP complexes at different pH's. The separation of these chelates was achieved within 7 minutes. The obtained results were compared with speciation and a reasonable agreement was observed, although the separation ofmetal-PASP showed poor broad peaks. / AFRIKAANSE OPSOMMING: Die elektrochemiese analise van geselekteerde metaal-ione met nuwe biodegredeerbare chelate, Iminodisuksien suur (IDS) en Polyaspartiese suur was gedoen met sikliese voltametrie deur gebruik te maak van 'n dun laag kwik glasagtige koolstof mikroelektrode. Vanaf'n omgewingsstandpunt is IDS en PASP van belang. Hulle was voorgestel as alternatiewe vir chelate en verspreidingsagente. Die termodinamies stabiliteits konstantes van hierdie uitgesoekte metal komplekse was bepaal deur middel van sikliese voltametrie (CV). 'n Vergelyking met soortgelyke data, wat met potensiometriese metodes bepaal was, dui 'n goeie korrelasie aan tussen die twee metodes bepaal was. Dit bevestig die feit dat CV 'n bruikbare en maklike manier is om metal ligand komplekse se termodiniese data te evalueer. Die resultate was ook gebruik om die voorspelde model, wat verkry was deur gebruik te maak van "Equilibrium Speciation model JESS program, te bevestig. Kapillere elektroforese (CE) was gebruik om metal-IDS en metal-PASP komplekse by verskillende pH's te skei. Die skeiding van hierdie chelate was binne sewe minute verkry. Hierdie resultate was vergelyk met die spesiasie data en 'n aanvaarbare ooreenstemming was waargeneem, alhoewel die skeiding van die Metaal-PASP swak pieke toon.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy