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Heat exchange systems used in everything from cars to microelectronics have rapidly advanced in recent years to offer high heat transfer rates in increasingly smaller sizes. However, these systems have become essentially optimized using conventional heat transfer fluids. To test the viability of nanofluids as a new heat transfer fluid, an experimental investigation was designed using a constant pressure drop configuration to drive flow into a heated square microchannel test section. The experimental trials included seven different test fluids tested over varying concentrations and surfactant use. Two identical test sections were used to collect results on heat transfer rates, pressure drop, mass flowrate and pumping power for all fluids. These results show a heat transfer improvement for nanofluids of 8-16% over pure water, with no meaningful increase in pumping power. This result is highly desirable, as it indicates an easily obtainable heat transfer improvement without an associated pumping cost increase. Importantly, the experiment shows the potential viability of nanofluids for heat transfer applications, while acknowledging limitations such as long term nanofluid stability. / text

“Une vie incomplète”: Le cas particulier de la colonia Miguel Hidalgo, Ecatepec, État de México Tout en défiant l’anthropologie classique, cette étude montre la manière selon laquelle les perspectives intimistes peuvent contribuer à la compréhension de phénomènes sociaux. Le point de départ est celui de l’histoire personnelle de l’auteure et la méthode employée implique la reconnaissance d’une problématique partagée avec l’altérité étudiée ici. Cependant, il ne s’agit pas d’un récit autobiographique mais bien d’une tentative de saisir dans le dialogue avec autrui des réponses à un avenir individuel et collectif. En cela, l’objectif est d’expliquer comment est-ce que les habitants d’un quartier défavorisé, comme celui de Miguel Hidalgo dans la périphérie de la Ville de Mexico, s’organisent pour faire face aux multiples infortunes qui mettent en péril leur vie dans le quotidien, et d’établir quels sont les différents facteurs qui interviennent dans le fait que certains individus parviennent à réaliser une trajectoire d’ascension sociale alors que d’autres non. Cette thèse décrit d’abord le mode selon lequel les habitants se sont organisés pour satisfaire leurs besoins de base et faire face à leur situation défavorable. Elle examine ensuite l’existence d’un modèle socioéconomique, étendu à la communauté, fondé sur la transformation de l’unité domestique dans une unité de production. Elle explore ensuite les possibilités qu’ont les habitants du quartier de Miguel Hidalgo d’accomplir une certaine ascension sociale grâce aux études. Elle montre aussi les modes selon lesquels les résidents de cette zone prétendent transformer la société, pour réaffirmer les liens communautaires ou bien pour construire de nouvelles identités. En conclusion, il est établi que, même quand dans une large mesure les jeunes ont été ceux qui ont impulsé la transformation et la dilution de la société, ce sont eux qui actuellement s’efforcent davantage à récupérer les valeurs communautaires et produire de nouvelles formes pour leur expression. / “Living an Incomplete Life”: The Particular Case of the Miguel Hidalgo Neighborhood, Ecatepec, Mexico This study shows the manner in which an intimate perspective may contribute to the understanding of social phenomenons, as a means to challenge classical anthropology. The starting point is the author’s personal history, used as a method that entails the recognition of shared issues with the otherness that she seeks to study. However, this is not an autobiographical tale, but an attempt to find, through dialogue with the other, answers about the individual and collective process of becoming. The goal is to explain how the inhabitants of Miguel Hidalgo, an underprivileged neighborhood in Mexico City’s periphery, organize themselves in order to confront the myriad of vicissitudes which put their livelihoods at risk from day to day, and to establish which are the different factors that intervene in the fact that some individuals achieve a certain level of social mobility, while others do not. The starting point is the description of the way in which neighbors organize in order to fulfill their basic needs and confront the challenging situation. It is also proposed that a socioeconomic model, based on the transformation of the household into a unit of production, has spread throughout the community. The possibilities for social mobility of Miguel Hidalgo residents through education are then explored. The means by which the residents of the area pretend to transform society, either to reassert community bonds or to build new identities, are also shown.The study concludes by proposing that, although it has been the youth the ones which have impelled the transformation and dilution of society, it is also they the ones that put up a bigger effort in regaining community values and in producing new forms for their expression.

Los escaparates virtuales, la venta online y la puesta en valor de los circuitos de producción cortos y agroecológicos a través de eficaces políticas de comunicación en las redes sociales son ejemplos de lo que hoy están usando muchos pequeños comerciantes para poner en valor su expertise tradicional, paradójicamente basada en la cercanía y el trato directo. en este artículo analizamos el papel de las tecnologías digitales en la re-significación y re-activación del pequeño comercio y de los mercados de abastos tradicionales. el uso de tecnologías digitales pone en entredicho la visión de Internet como agente de desterritorialización y de creación de una cultura global, ante la presencia de nuevas formas de localización basadas en la emergencia de nuevas formas de convivialidad, agroecología y alimentación saludable. / Virtual storefronts, online sales, the enhancement of short and agroecological circuits of production through effective communication policies in social networks, are strategies that many small businesses are now using to value their traditional expertise, paradoxically based on proximity and direct treatment. this article analyzes the role of digital technologies in the re-signification and re-activation of small businesses and traditional markets. the use of digital technologies challenges Internet as an agent of deterritorialization and creation of global culture, in front of the presence of new forms of localization based on the emergence of new forms of conviviality, agroecology and healthy eating.

Thesis (MPhil (Sociology and Social Anthropology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The Internet has long stimulated thought and discussion around the idea of an alternative economy based on reciprocal exchange. To date, however, the benefits of this gift economy have been largely limited to the realms of cyberspace. Despite the dramatic changes in social interaction and exchanges facilitated by online networking, and the evolution of what may be referred to as a ‘high-tech gift economy’, the potential of the Internet to really revolutionize economic systems has been limited, as the gifting involved did not extend beyond the realms of cyberspace. By contrast to this global, virtual, gift economy that has developed online, this thesis explores the way in which Information and Communication Technologies (ICTs), traditionally renowned for enhancing global reach, can be used to build and strengthen local exchange systems using community currencies. The research focuses specifically on the emergence of an alternative online currency, the Community Exchange System (CES), which originated in Cape Town towards the end of 2002, and has since spread to be used by 218 exchanges in 29 countries. Particular attention is paid to the pilot exchange that was launched in Cape Town, namely the Cape Town Talent Exchange (CTTE). The thesis proposes that web-based community currencies can provide an alternative to the current economic system, allowing for a relationship-centred approach to exchange that can be likened to a type of gift economy, centred on the principle of reciprocity, and fostering a spirit of abundance over scarcity. By doing so it is proposed that what Karl Polanyi (1944) referred to as the ‘great transformation’ of the 20th century, characterised by a shift in emphasis from human relationships to market price mechanisms, may be reversed in the ‘network society’ (Castells, 1996), in which principles of reciprocity and gift exchange are re-embedded in ‘relationship economics’ (Deragon, 2007). Part A provides a review of literature pertaining to online anthropology and the concept of a reciprocal gift ‘e-conomy’, the social dimension of economics, and the theory of ‘money’ and alternative currencies. Part B provides an overview of research findings pertaining to the CES as example of an alternative community currency operating a web-based platform, beginning with an introductory overview of the CES and CTTE, followed by a look at issues pertaining to reciprocity, and speculation on possible futures for this and similar web-based community currency systems. / AFRIKAANSE OPSOMMING: Die Internet prikkel al lank idees en gesprekke oor ‘n alternatiewe ekonomie gebaseer op, ‘geskenk-handel’. Tot dusver is die voordele van hierdie ’geskenk-ekonomie’ egter beperk tot die dimensies van die kuber-ruimte. Ondanks dramatiese veranderinge in sosiale verkeer, uitruil en handel wat deur die aanlyn-netwerke bewerkstellig is, en die evolusie van wat as ‘high-tech geskenk ekonomie‘ beskryf kan word, was die potensiaal van die Internet om werklik ekonomiese sisteme om te keer, beperk. In teenstelling met die globale, virtuele geskenk/uitruil-ekonomie wat aanlyn ontwikkel het, ondersoek hierdie tesis die manier waarop Informasie en Kommunikasie Tegnologieë, tradisioneel bekend vir hul globale reikwydte, gebruik kan word om plaaslike uitruilsisteme te bou en te versterk. Die navorsing lê klem op die ontstaan van ‘n alternatiewe aanlyn-geldeenheidsisteem, die Gemeenskaps Uitruil Sisteem (‘Community Exchange System’ CES), wat aan die einde van 2002 in Kaapstad ontstaan het. Dit het sedertdien uitgebrei na 218 uitruilskemas in 29 lande. Spesiale aandag val op die loods uitruilskema wat in Kaapstad begin is, te wete die Cape Town Talent Exchange (CTTE) (Kaapstadse Talent Uitruilskema) Die verhandeling voer aan dat ‘n web-gebaseerde gemeenskapmark ‘n alternatiewe ekonomiese sisteem kan teweegbring. Dit kan lei tot ‘n benadering tot uitruil wat verhoudings-gesentreerd is, vergelykbaar met ‘n soort geskenk-ekonomie wat toegespits is op die beginsel van wederkerigheid. So kan ‘n oorvloed-bewustheid, pleks van skaarsheidsbewustheid bevorder word. Dit word aangevoer dat dit waarna Karl Polanyi (1944) as die ‘Groot Transformasie’ van die 20ste eeu verwys het, gekarakteriseer deur ‘n klemverskuiwing van menslike verhoudings na markgedrewe meganismes, kan terug verander na ‘n ‘netwerk-gemeenskap’ (Castells, 1996). Hierin is die beginsels van wederkerigheid en geskenk-uitruil ingebed in 'n tipe ‘verhoudings-ekonomie’ (Deragon, 2007). Deel A gee ‘n oorsig van die literatuur oor aanlynantropologie en die konsep van ‘n wederkerige geskenk ‘e-ekonomie’, die sosiale dimensie van ekonomie, en die teorie van ‘geld’ en alternatiewe betaalmiddele. Deel B gee ‘n oorsig van navorsingbevindings ten opsigte van die CES en CTTE as voorbeeld van ‘n alternatiewe gemeenskapsbetaalmetode wat van ‘n webgebaseerde platform gebruik maak. Dit word, gevolg deur opmerkings oor wederkerigheid (en) spekulasie oor die moontlike toekoms daarvan en van soortgelyke Internet-gebaseerde gemeenskapsbetaalsisteme.