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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Surfactant stabilization of CO₂-in-water foams at high temperatures

Chen, Yunshen 25 September 2014 (has links)
The interfacial properties of a surfactant in a CO₂-aqueous system at a temperature above 100 °C, and how they influence foams are essentially unknown. A cationic surfactant, C₁₂₋₁₄N(EO)₂ in the protonated state below pH 5.5, was demonstrated to be soluble in an aqueous phase with up to 22% total dissolved salt (TDS) at 120 °C. Moreover, the strong solvation in brine (high cloud point) and simultaneous affinity for CO₂ led to significant adsorption of the surfactant at the CO₂-water interface. Given that the surfactant favored the brine phase over the CO₂ phase, the preferred curvature was a CO₂-in-water (C/W) macroemulsion (foam). The surfactant stabilized foam in the presence of crushed calcium carbonate at ~ pH 4 upon suppressing the dissolution of calcium carbonate upon addition of Ca²⁺ and Mg²⁺ according to the common ion effect. Cationic alkyltrimethylammonium surfactants with an alkyl tail of average carbon number less than 15 were soluble in 22% TDS brine up to 120 oC. The head group was properly balanced with a C₁₂₋₁₄ hydrocarbon tail for a sufficiently dense surfactant layer at the CO₂-water interface to reduce the interfacial tension. For C₁₂₋₁₄N(CH₃)₃Cl the solubility in brine and the surfactant adsorption were sufficient to stabilize C/W foam at 120 °C in both a crushed calcium carbonate packed bed (76 Darcy) and a capillary tube at the downstream of the bed. The stability of the foam at high temperature may be attributed to the high surfactant adsorption at the interface. The use of nonionic surfactants as a foam stabilizer is usually limited by their poor aqueous solubility at elevated temperatures, particularly at high salinity. A nonionic surfactant C₁₂₋₁₄(EO)₂₂ with high degree of ethoxylation gave higher salt tolerance at elevated temperature. The surfactant stabilize C/W foam at 80 °C in the presence of 90 g/L NaCl brine in a 30 Darcy sand pack, which has not yet been reported by a nonionic surfactant. Both the formation of strong foam in the porous media and the low of oil-brine partition coefficient suggest C₁₂₋₁₄(EO)₂₂ is a potential candidate for a CO₂ EOR field trial. / text
102

Co-branding ur ett konsumentperspektiv : En fallstudie av företaget Sony Ericsson

Thomas, Elias, Wahlén, Jenny January 2006 (has links)
<p>Syftet med uppsatsen har varit att undersöka hur konsumenterna uppfattar varumärkesutvidgningen. Studien har haft fokus på ett fallföretag, Sony Ericsson samt de varumärken (Walkman och Cyber-shot från Sony) som de använder på deras produkter. Vi har samlat in data med konsumenters uppfattningar om co-branding och deras brukande av produkter ur den kategori där de co-brandade varumärkena finns. Vidare har vi sökt efter förklaringar till huruvida det finns någon koppling mellan användandet av Mp3-spelare och digitalkamera i förhållande till betydelsen av varumärkena. Undersökningen har varit helt webbaserad och samlat in över 200 svar varvid 197 har använts i sammanställningen av enkätsvaren.</p><p>Vi har använt oss av rådande teorier inom varumärken, varumärkeshantering, varumärkesvärdering och varumärkesfusioner. De teorier som ligger till grund för uppsatsen är Brand Management, Brand Equity, och Co-branding. Detta har tillåtit oss att gå från generella beskrivningar om varumärken fram till hantering och värdering av varumärken för att slutligen nå kärnan av uppsatsens tema det vill säga co-branding.</p><p>Resultatet av undersökningen blev att det råder hög kännedom om Mp3-varumärket Walkman med en kännedom på nio av tio tillfrågade, medan drygt fyra av tio kände till digitalkamera- varumärket Cyber-shot. Av de tillfrågade som dessutom använder sig av någon av de respektive produkterna är kännedomen om förknippat varumärke ännu högre. Betydelsen av varumärkena har trots olika kännedom varit ungefär lika stora och legat under det godkända värdet på tre i den femgradiga skalan. Män har prioriterat och värderat Mp3-spelarfunktionen och Walkman högre än motsvarigheten till digitalkamera, medan kvinnornas prioritet har varit hos kamerafunktionen och Cyber-shot varumärket.</p><p>Vi har kunnat dra slutsatserna att två starka varumärken som kombineras inte bidrar med lika stor synergi som ett lågvärdesvarumärke får när det kombineras med ett högvärdesvarumärke. Då varumärkena Walkman och Cyber-shot visat sig vara starka som enskilda varumärken samtidigt som Sony Ericsson är ett företag med högt anseende innebär varumärkesutvidgningen för Sony Ericssons mobiltelefoner inga ökade fördelar för Sony Ericsson.</p><p>Hos dem som använder Mp3-spelare och digitalkameror har vi kommit fram till att det finns en högre kännedom om varumärkena samt att varumärkena är av större vikt när de co-brandats. Detta tycks bero på att ökad kännedom ger mer kunskap om alternativen på marknaden och skapar därför medvetenhet och preferenser hos konsumenterna.</p><p>Slutligen har vi i denna undersökning upptäckt ett samband där de konsumenter som prioriterat funktionerna högt även har haft en hög prioritering av förknippat varumärke.</p>
103

The representation and interpretation of change in intimate relationships : a study of homosexual and heterosexual couples

Satchell, Margaret G. January 2001 (has links)
No description available.
104

Preparation, characterisation and applications of metal complexes and metal containing vinyl polymer systems

Bonner, J. G. January 1993 (has links)
No description available.
105

Study of the reactivity and spectroscopic properties of compounds with metal-metal bonds

Pimblett, G. January 1986 (has links)
No description available.
106

From constraint to opportunity : an exploration of Ireland and Sweden's experience of relating neutrality to participation in EU's CFSP

Karakus, Mehmet January 2002 (has links)
No description available.
107

Agricultural co-operatives and changes in Greek agriculture since 1949

Lappas, N. January 1987 (has links)
No description available.
108

Anaerobic Co-digestion of Organic Fraction of Municipal Solid Waste with Municipal Sludge with or without Microwave Pre-treatment

Ara, Efath 16 July 2012 (has links)
Anaerobic co-digestion of organic fraction of municipal solid waste (OFMSW), with thickened waste activated sludge (TWAS) and primary sludge (PS) has the potential to enhance (biodegradation) of solid waste, increase longevity of existing landfills and lead to more sustainable development by improving waste to energy production. This study reports on mesophilic batch anaerobic biological methane potential (BMP) assays carried out with different concentrations and combinations (ratios) of OFMSW, TWAS (microwave (MW) pre-treated and untreated) and PS to assess digester stability and potential improved specific biodegradability and potential increased specific biogas production by digestion of OFMSW with PS and TWAS in various tri-substrate mixtures. Results indicated improvements in specific biogas production with concomitant improvements in COD and volatile solid (VS) removal for co-digestion of OMSW, TWAS and PS vs. controls. In terms of improvements in biogas production and digester stability the OFMSW:TWAS:PS:50:25:25 ratio with or without TWAS MW treatment was deemed best for further continuous digester studies. At a 15d HRT which is the regulatory policy in the province of Ontario for municipal mesophilic anaerobic TWAS:PS treatment, co-digestion of OFMSW:TWAS:PS, and OFMSW:TWASMW:PS resulted in a 1.38 and 1.46 fold relative improvement in biogas production and concomitant waste stabilization when compared to TWAS:PS and TWASMW:PS digestion at the same HRT and volumetric VS loading rate respectively. Treatment of OFMSW with PS and TWAS provides beneficial effects that could be exploited at MWWTP that are being operated at loading rates less than design capacity.
109

Preparation and properties of ultrafine magnetic particles

Wells, S. January 1989 (has links)
No description available.
110

Une approche géographique des parcs co-frontaliers entre les États-Unis et le Canada : politiques, coopérations et conflits : Les exemples des parcs nationaux de Glacier et des lacs Waterton, de Wrangell-Saint Elias et de Kluane, de North Cascades et des parcs provinciaux du lac Chilliwack et de la vallée de la Skagit / A geographical approach of co-border parks between the United-States and Canada : politics, cooperations and conflicts : Case studies of Glacier and Waterton Lakes, Wrangell-Saint Elias and Kluane and North Cascades National Parks and Chilliwack Lake and Skagit Valley Provincial Parks

Moumaneix, Caroline 23 November 2012 (has links)
Le premier parc national, Yellowstone, est né en 1872, aux États-Unis. Le Canada s’est inspiré puis éloigné de ce modèle. Les points communs entre ces deux pays sont nombreux : la wilderness, la conquête et la maîtrise du territoire, la création des premiers parcs, emblèmes identitaires forts. La comparaison des parcs co-frontaliers entre les États-Unis et le Canada souligne leurs apports réciproques. Compte-tenu de ces éléments, on devrait constater de réelles dynamiques de coopération, une proximité dans le zonage et la politique de gestion des parcs, une place similaire réservée aux populations locales et peu de conflits de part et d’autre de la plus longue frontière pacifique du monde. Cependant, notre étude, fondée sur des entretiens menés auprès des employés et des résidents des parcs et sur l’analyse de documents officiels, révèle des divergences entre ces parcs co-frontaliers. La wilderness et la frontière internationale sont perçues différemment. La réalité de la coopération transfrontalière ne correspond pas aux discours officiels. De multiples frontières internes fragmentent les parcs et affectent leur capacité à coopérer. Ces limites révèlent l’importance des populations locales, allochtones et autochtones, des associations, inégalement prises en compte par les autorités gestionnaires. Les enclaves privées dans les parcs américains conduisent à des conflits importants entre leurs propriétaires et le National Park Service. Au Canada, les tensions internes sont plus limitées. Au travers d’une volonté commune de protection de la wilderness, les parcs co-frontaliers affichent une coopération inégale et des fragmentations internes qui esquissent des régions bordières donnant une autre dimension à la frontière internationale.À partir d’un même modèle, le Canada et les États-Unis se différencient en matière de gestion, de coopération et d’implication des populations locales. Les États-Unis n’étant plus l’unique modèle en matière de parcs, le Canada se pose peut-être comme un modèle alternatif… / The first national park, Yellowstone, was created in 1872 in the United States. Canada was inspired by this model, before turning away from it. These two countries have many things in common: the wilderness, the conquest and control of territory, the creation of parks as strong markers of identity… A comparison of co-border parks between the US and Canada underlines their mutual contributions. Considering these facts, a real dynamic of cooperation should be observed: similar park zonings and management policies, a similar approach of local populations and very few conflicts on each side of the longest undefended borderline in the world. However, our study, based on interviews with both employees and inholders as well as on analysis of official documents, reveals divergences between these co-border parks. The wilderness and the international borderline are perceived differently. The reality of transboundary cooperation does not correspond to the official discourse. Numerous internal boundaries are fragmenting the parks and are thus affecting their capacity for cooperation. These limits reveal the importance of local populations, non-natives and natives, as well as associations that are considered unequally by park managers. The American parks inholdings lead to significant conflicts between the inholders and the National Park Service. In Canada, private property having been banned, internal tensions are more limited. Through a common will to protect wilderness, co-border parks show an unequal cooperation and internal fragmentations which outline border regions, giving another dimension to the international border. From an identical model, Canada and the United States are becoming differentiated in the matters of management, cooperation and the implication of the local populations. The US no longer being a unique model in the matter of parks, Canada may be rising as an alternative model…

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