• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1389
  • 302
  • 71
  • 51
  • 48
  • 22
  • 22
  • 22
  • 21
  • 17
  • 14
  • 14
  • 8
  • 8
  • 8
  • Tagged with
  • 2010
  • 807
  • 542
  • 368
  • 291
  • 208
  • 200
  • 165
  • 151
  • 141
  • 136
  • 135
  • 129
  • 122
  • 120
  • 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

Avaliação da qualidade do ar interior em jardins de infância

Santos, Joana Carvalho dos January 2010 (has links)
Estágio realizado no Instituto Nacional de Saúde Doutor Ricardo Jorge no Porto e orientado pelo Doutor João Paulo Fernandes Teixeira / Tese de mestrado. Engenharia de Segurança e Higiene Ocupacionais. Faculdade de Engenharia. Universidade do Porto. 2010
2

Monitorização da qualidade do ar utilizando redes sem fios oportunistas

Azevedo, Mónica Sofia Rei de January 2010 (has links)
Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Automação). Universidade do Porto. Faculdade de Engenharia. 2010
3

Obtenção de filtros de ar com fibra polimérica para equipamento de ar- condicionado com fluido refrigerante variável (VRF)

Alves, José Roberto Pereira 06 December 2016 (has links)
Submitted by Rosa Assis (rosa_assis@yahoo.com.br) on 2017-04-10T15:21:58Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) José Roberto Pereira Alves.pdf: 6744375 bytes, checksum: 356013c3caaf9d38880fbe8c30dc646a (MD5) / Approved for entry into archive by Paola Damato (repositorio@mackenzie.br) on 2017-04-20T15:40:48Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) José Roberto Pereira Alves.pdf: 6744375 bytes, checksum: 356013c3caaf9d38880fbe8c30dc646a (MD5) / Made available in DSpace on 2017-04-20T15:40:48Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) José Roberto Pereira Alves.pdf: 6744375 bytes, checksum: 356013c3caaf9d38880fbe8c30dc646a (MD5) Previous issue date: 2016-12-06 / In the composition of the air-conditioning system, the air filter is one of the components that have great importance for air quality and for the proper functioning of the system. In this work, we analyzed the air-conditioning system and air filtering mechanism and its chemical and physical solids retention compositions, which includes the powder in this condition, and compared thick air-conditioning filters that have Polymers in their composition. In view of the need to evaluate the efficiency according to some guidelines of NBR 161O1, air filters were developed with non-woven polyester, viscose and cellulose acetate which, in addition to seeking to comply with the standards NBR 16101 (2012) and 16401 (2008), are committed to reduce the space used by the filters in the companies, to reduce costs, to obtain information about partiele retention and to have less loss of load, when compared to the type of filter most used in the market. In the retention tests, the granular materiais of phyllite and talc were used because of their size characteristics and ability to penetrate the filters. It was also possible to have a lower price being around three times smaller compared to the conventional filter most used in the market. In contrast, the conventional filter most used for the air-conditioning system has greater particle retention and less loss of charge. Inside. Also developed filter samples more suitable to the equipment assembled for the load loss and particle retention tests. / Na composição do sistema de ar-condicionado, o filtro de ar é um dos componentes que têm grande importância para a qualidade do ar e para o funcionamento adequado do sistema. Neste trabalho, analisaram-se o sistema de ar-condicionado e o mecanismo de filtragem do ar e suas composições química e física de retenção de sólidos, o que inclui o pó nessa condição, e compararam-se filtros grossos de ar-condicionado que têm polímeros em sua composição. Diante da necessidade de avaliar a eficiência de acordo com algumas orientações da NBR 16101, desenvolveram-se filtros de ar com os não tecidos de poliéster, viscose e acetato de celulose que, além de procurar atender às orientações das normas NBR 16101 (2012) e 16401 (2008), têm o compromisso de reduzir o espaço utilizado pelos filtros nas empresas, reduzir custos, obter informações sobre a retenção de partículas e ter menor perda de carga, quando comparados ao tipo de filtro mais utilizado no mercado. Utilizou-se, nos testes de retenção, materiais granulados de filito e talco devido às suas características de tamanho e capacidade de penetração nos filtros. Foi possível também obter um preço em tomo de três vezes menor, em comparação ao filtro convencional mais utilizado no mercado. Em contrapartida, o filtro convencional mais utilizado para o sistema de ar-condicionado tem maior retenção de partícula e menor perda de carga. Desenvolveu-se também amostras de filtros mais adequados ao equipamento montado para os testes de perda de carga e retenção de partícula.
4

A influência das reclamações dos condicionadores WRAC na satisfação dos clientes

Silva, Gilsomar Gabriel da January 2002 (has links)
As organizações com o objetivo de ser cada vez mais competitivas em um mundo globalizado e extremamente competitivo buscam oferecer produtos e serviços que agreguem valor aos seus clientes, aumentando, assim, sua satisfação. A insatisfação dos clientes, especificamente, tem se mostrado de grande importância, pelos seus impactos negativos no desempenho econômico de médio e longo prazo nos resultados das empresas, e não nos seus aspectos de curto prazo. Este trabalho se constituiu na realização de uma pesquisa descritiva sobre a satisfação dos consumidores de condicionadores de ar tipo WRAC da Springer Carrier onde foram levantados os atributos considerados importantes para os clientes, o nível de importância destes atributos, o nível de satisfação em relação a estes atributos e as conseqüências da insatisfação destes consumidores. Este trabalho foi realizado com 300 clientes que reclamaram ao call center da Springer Carrier. Entre as conclusões encontram-se os atributos onde os consumidores apresentam maior insatisfação, sendo eles o serviço pós-venda e a assistência técnica e finalmente sugestões para a empresa. / The organization’s which their main goal consists on being more competitive in a globalized and extremely competitive world, are trying to offer to their customers products and services that add value and increase customers satisfaction. Dissatisfaction is very important to companies, since it has a big impact in the financial results at medium and long term. This job consists in a descriptive study about the Springer Carrier WRAC(Window Room Air Conditioning) customers satisfaction. Through the qualitative study we identified the most important products features and dissatisfaction causes, which had their level of importance and satisfaction measured through a structured questionnaire. Besides, we identified some of the consequences of dissatisfaction, as well as the likelihood of the customers on expressing these behaviors. The survey was applied to 300 customer’s which had problems and had claimed to Springer Carrier by the calling the Call Center department. Among our conclusions, we found that the attributes which the customers are more dissatisfied with after-sales and technical support. Also, the managerial implications may be highlighted.
5

Análises acústicas para instalação de sistemas de ar condicionado / Acoustic analyses for installation of air conditioning systems

Lagemann, Carlos Henrique January 2008 (has links)
A instalação inadequada de grandes sistemas de ar condicionado pode ter como conseqüências a geração de conflitos com a comunidade local e o desencadeamento de processos judiciais, envolvendo elevados montantes, visto que o ruído gerado por estes equipamentos pode afetar a vida de muitas pessoas. O desligamento destas unidades, por ordem judicial, geralmente impede o funcionamento de hotéis, shopping centers, centrais de informática e processos industriais. Este trabalho visa fornecer subsídios técnicos para equipes de projeto de instalação destes equipamentos, formadas por projetistas, engenheiros e arquitetos. Neste sentido, busca-se apresentar a análise e possíveis soluções de forma prática. É necessário que o projeto de instalação destes equipamentos seja robusto, levando em conta todos os aspectos pertinentes. O ponto inicial de qualquer projeto deve ser o mapeamento da região onde os equipamentos serão instalados, buscando identificar o ruído já existente nos horários em que os equipamentos estarão em operação. A partir desta análise, identifica-se qual o nível de ruído ideal para a aplicação, levando-se em conta a distância disponível entre os equipamentos e a comunidade, a legislação vigente e tipos de equipamentos oferecidos pelo mercado. São apresentadas soluções para atenuação de ruído em casos críticos em que os aspectos mencionados não foram levados em consideração ou não puderam ser aplicados. Mostra-se a influência da instalação de atenuadores de ruído no rendimento das centrais de refrigeração e estima-se o custo de implementação. Mostra-se a construção e aplicação dos conceitos propostos e são analisadas instalações visitadas no decorrer deste trabalho. / An inadequate installation of large air conditioning systems can create neighborhood conflicts and lead to great legal expenses, due to the fact that these equipment noise can affect the normal way of living of these people. If these units were turned off by a judicial request, the operation of hotels, malls, information nucleus and industrial process may be suspended. This work is supposed to give the technical basis to installation project teams, which are formed by engineers and architects. In this sense, this work intends to present analysis and possible solutions in a practical way. The installation project must be strong according to their own peculiar aspects. Any project must start with the recognition of the area where the equipment are going to be installed, aiming the identification of the noise level in place during specific periods when the apparatus will operate. Through these analyses it will be possible to identify the noise level and the correct equipment to be installed, the distance between equipment and neighborhood in order to comply with current Legislation. This work will show solutions for noise attenuation for special cases in which these aspects were not considered or could not be applied. The influence of noise attenuation on large air conditioning systems performance is presented, as well as the installation costs. The construction and application of the proposed concepts are presented too. Analyses of installations visited during this work are also mentioned.
6

Desenvolvimento de uma bomba de calor

Ferreira, Fernando José Mota January 2009 (has links)
Estágio realizado na MARTIFER ENER-Q e orientado pelo Doutor Pedro Correia de Carvalho / Tese de mestrado integrado. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 2009
7

Estudo experimental e numérico da distribuição de velocidade do ar num recinto climatizado

Andrade, José Abel Ferreira de January 1985 (has links)
Dissertação apresentada para obtenção do grau de Mestre em Engenharia Térmica, na Faculdade de Engenharia da Universidade do Porto, sob a orientação do Prof. Doutor António de Oliveira Restivo
8

Uma metodologia para a caracterização de fluxos de ar multizona em edifícios

Afonso, Clito Félix Alves January 1989 (has links)
Dissertação apresentada para obtenção do grau de Doutor em Engenharia Mecânica, na Faculdade de Engenharia da Universidade do Porto, sob a orientação do Prof. Doutor Eduardo Maldonado
9

China's Strategy toward Taiwan in the Post-Cold-War Period (1989-2000)

Chung, Chue-Chen 04 July 2001 (has links)
Abstract Military strategy is in serve of national interests, which is my basic idea through the whole paper. The theme of this paper is ¡§Mainland China's Military Strategy toward Taiwan in the Post-Cold-War Period¡¨. It can be divided into four folds: Firstly, the characteristics of post-cold war and its impact on the formation of military strategy of Mainland China. Secondly, the difference of military strategy thought between three China national leaders. Thirdly, possible military strategies and actions that China might take to against Taiwan. Lastly, the future challenge Taiwan might face and the way to get along with China's superior military power. This thesis has six chapters. In First chapter I introduce my research motive, method, structure, goal, and also define the content of military strategy. Then, in Second chapter I analysis the changing situation of the world and how it impacts Mainland China's national interests, and goals. Third chapter, I survey the thought of Mainland China's strategy. Fourth chapter is the discussion about the possible strategy and action that would be used by Mainland China's military against Taiwan. Fifth chapter discuss the future challenge and opportunity bring in by the relationship across Taiwan Strait. In Chapter Six I portray the future relationship development across Taiwan Strait and give some suggestion to Taiwan government. Based on the result of my research, I conclude that the main military strategy of China against Taiwan is a 'deterrent military strategy' enforced by a high technology war. Unfortunately, China seems on the track toward its goal. On the other hand, threaten by superior military power of China; Taiwan¡¦s military strategy simply could be described by four words 'Firmly defending, Effective deterrence.' However, the context could be expressed by two concrete approaches: 1. Reinforce his military and logistics capabilities in preparing to face the coming severe campaign launched by the Mainland China. 2. Equip himself with anti-missile facilities as part of his negotiate power when reluctantly forced to deal with the opponent on the table.
10

Radioargon production at The University of Texas at Austin

Egnatuk, Christine Marie 19 November 2012 (has links)
The interest in the detection of radioargon isotopes--³⁷Ar, ³⁹Ar, and ⁴²Ar--is increasing important for on-site inspections within the Comprehensive Nuclear-Test-Ban Treaty verification regime. In an underground nuclear explosion ³⁷Ar is produced by ⁴⁰Ca(n,[alpha])³⁷Ar reaction in surrounding soil and rock. With a half-life of 35 days, ³⁷Ar provides a signal useful for confirming the location of an underground nuclear event. The development of detector systems is underway. This work produced radioargon isotopes by three methods for the development and testing of radioargon detection systems. The irradiation of argon gas at natural enrichment in the 3L facility within the Mark II TRIGA reactor facility at The University of Texas at Austin provides a source of ³⁷Ar for the calibration of the ULBPC in development at PNNL. The ⁴¹Ar activity is measured by the gamma activity using an HPGe detector after the sample is removed from the core. Using the ⁴¹Ar/³⁷Ar production ratio and the ⁴¹Ar activity, the amount of ³⁷Ar created is calculated. The ⁴¹Ar decays quickly (half-life of 109.34 minutes) leaving a radioactive sample of high purity ³⁷Ar and only trace levels of ³⁹Ar. The second method was the irradiation of a calcium-containing compound. This option is not the best match for the TRIGA reactor type due to the thermal neutron flux. Therefore, the use of the Cd-lined 3L irradiation canister minimized the thermal activation of impurities while still allowing the majority of the ⁴⁰Ca(n,[alpha])³⁷Ar reactions occur. The third and last irradiation technique was a large volume, in-core gas facility developed at The University of Texas at Austin MARK II TRIGA reactor to produce a sample of ⁴²Ar with an activity above 1 mBq. The method requires a large volume, 1.4 L, of natural argon gas (99.6003% ⁴⁰Ar) at about 1 atm and three-12 hour irradiation periods. The production of ⁴²Ar requires a double capture to be produced from the stable 40Ar isotope. This method produced 940 kBq of ³⁹Ar, 3.08 MBq ³⁷Ar, 114 GBq ⁴¹Ar, and 0.311 Bq ⁴²Ar at the end of the final irradiation period. / text

Page generated in 0.0413 seconds