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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.
1

Modelling heat transfers in a supermarket for improved understanding of optimisation potential

Hill, Frances January 2016 (has links)
Energy demand attributable to the operation of supermarkets on-site is thought to be responsible for 1% of UK greenhouse gas emissions. In use data show a performance gap approaching a factor of three for overall energy use, with a gap of a factor of six in energy demand for heating. This performance gap indicates significant faults in the conventional modelling route. Current building regulations in the UK require the "building related" energy use of new commercial buildings to comply with particular requirements. Supermarket buildings are therefore modelled according to these protocols to establish their predicted energy demand. The impact on this predicted energy demand of the exclusion of process energy (eg for refrigeration) from these protocols is explored by modelling a supermarket retail floor with heat transfers related to refrigerated cabinets, and comparing the sensitivities of such models with those of models compliant with regulatory protocols. Whereas models compliant with regulatory protocols indicate an advantage of limiting the level of insulation and airtightness, and allowing stratification, to facilitate heat loss through the store envelope; models that include heat transfers around the refrigerated cabinets are found to show that energy demand may be decreased by up to 40% by doubling both insulation and airtightness, and by destratification. This will, however, only apply if rates of air change in buildings in use match those modelled. This shows the importance of including heat transfers around refrigerated cabinets in design modelling, so that appropriate decisions may be taken with respect to building envelope parameters. Compliance modelling protocols should be changed to reflect this. In order to facilitate this change and enable modelling of refrigerated cabinets within a compliance model through a few simple inputs, a set of data and associated algorithms is derived and offered for inclusion in compliance modelling tools.
2

Encapsulamento de [beta]-caroteno em nanotubos de carbono utilizando modelagem molecular / Encapsulation of ß-carotene in Nanotubes, Using Molecular Modeling Carbon

Moreira, Edvan 31 March 2008 (has links)
Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-06T19:33:29Z No. of bitstreams: 1 EdvanMoreira.pdf: 4583939 bytes, checksum: 5ab3a481fd56c037eec7e3edec77e8b9 (MD5) / Made available in DSpace on 2017-06-06T19:33:29Z (GMT). No. of bitstreams: 1 EdvanMoreira.pdf: 4583939 bytes, checksum: 5ab3a481fd56c037eec7e3edec77e8b9 (MD5) Previous issue date: 2008-03-31 / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA) / From its discovery, the nanotubes of carbon are seen as material’s highly promising for a lot of applications. The combination of nanotubes of carbon with other molecules is the most general form of modifying their properties. New methods to control and to tune these properties are necessary for the developing of their potentials applications. The functionalization has been proposed as one of the processes capable to modify the optical properties of the nanotubes of carbon, through chemical reaction ”it is arrested”another molecule in the surface of the nanotube. However, another more elegant form of functionalization is through the encapsulation of molecules inside the nanotube. Recently, the encapsulation of the molecule of the beta-carotene experimentally in nanotubes of carbon was accomplished and changes were verified in the absorption spectrum. In this work we performed simulations of molecular dynamics using field of similar universal force to test the encapsulation of the beta-carotene, and calculations of Electronic Structure to verify charge transference. The obtained results of the molecular dynamics confirm that the encapsulation of the -carotene happens in the three cases studied experimentally by Yanagi and collaborators. / Desde sua descoberta, os nanotubos de carbono são vistos como um material altamente promissor para muitas aplicações. A combinação de nanotubos de carbono com outra molécula é a forma mais geral de se modificar suas propriedades. Novos métodos para controlar e sintonizar estas propriedades são necessários afim de se desenvolver suas potenciais aplicações. A funcionalização tem sido proposta como um dos processos capaz de se modificar as propriedades ópticas dos nanotubos de carbono, através de reação química ”prende-se”a outra molécula na superfície do nanotubo. Entretanto, uma outra forma mais elegante de funcionalização se dá através do encapsulamento de moléculas no interior do nanotubo. Recentemente, foi realizado experimentalmente o encapsulamento da molécula do beta-caroteno em nanotubos de carbono e foram constatadas mudanças no espectro de absorção. Neste trabalho realizamos simulações de dinâmica molecular usando campo de força universal afim de verificar se o encapsulamento do beta-caroteno ocorre, e cálculos de Estrutura Eletrônica para verificar se há ou não transferências de carga no sistema. Os resultados obtidos da dinâmica molecular confirmam que o encapsulamento do beta-caroteno ocorre nos 3 casos reportados experimentalmente por Yanagi e colaboradores.

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