• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 17
  • 11
  • 4
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 49
  • 49
  • 15
  • 10
  • 9
  • 8
  • 7
  • 6
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 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

Reusable communicating systems

Taylor, Paul Nicholas January 1998 (has links)
No description available.
2

Les sols pollués : Leur remise en état au service de la justice environnementale / Non communiqué

Terrade, Vanessa de Fátima 28 June 2017 (has links)
Au sein des pays à vocation démocratique, les politiques publiques reconnaissent généralement qu’il est du devoir de l’État de promouvoir une société égalitaire, sans pauvreté,en réduisant les disparités sociales et en travaillant en faveur de la protection de l’environnement. Malheureusement, dans de nombreux États tels que le Brésil, l’application de ces politiques n’est pas effective, notamment en ce qui concerne le droit des personnes à disposer d’un logement sain. Il en résulte, que dans la pratique, nous voyons de nombreuses familles habiter sur des sites extrêmement pollués ou subir de graves atteintes à leur droit de jouir d’un environnement sain, du fait qu’elles vivent tout près d’industries polluantes. Il existe donc une violation manifeste des principes proclamés par ces États de Droit. Face à ce constat, l’objectif principal de cette thèse est de comprendre combien serait importante la gestion des sols pollués, à partir de l’adoption de lois concernant la remise en état de ceux-ci. Plus la loi portant sur la remise en état des sols serait développée, plus les mécanismes de contrôle des sites pollués et potentiellement pollués seraient étendus, et moins grands seraient les risques pour la population qui viendrait vivre sur ces sites ou dans les alentours de ceux-ci; ce qui, par conséquent, favoriserait la promotion d’un environnement sain pour tous, et l’émergence d’une société guidée par les principes de la justice environnementale. La méthodologie est adoptée dans le cadre du droit comparé, ce afin de démontrer l’évolution du droit fondamental à l’environnement en France et au Brésil et d’étudier des cas de pollution des sols dans ces deux pays. Le choix de ceux-ci s’explique par le fait que la France, pays industrialisé, possède déjà une certaine tradition dans le domaine du contrôle des sites pollués et potentiellement pollués ; contrairement au Brésil, pays en développement, qui est encore en train de chercher à déployer des mécanismes tournés vers la connaissance de ses sols et l’adoption d’un système d’inventaire national.De cette façon, il sera possible de comprendre l’importance de la législation environnementale et du contrôle de l’administration publique, afin de vraiment s’assurer du respect du droit fondamental à l’environnement pour la population de chacun de ces pays. Ensuite, nous évaluons les aspects socio-économiques des cas brésiliens, afin de comprendre la relation entre la pollution des sols et l’injustice environnementale dans ce pays. Ces diverses analyses nous amèneront à conclure que d’un point de vue juridique, il n’existe pas de lien flagrant entre, d’une part, la pollution des sols occasionnée par les entreprises du secteur industriel et, de l’autre, les disparités sociales existant au sein des pays. / Nos Estados Democráticos de Direito, as políticas públicas reconhecem um dever estatal de promover uma sociedade igualitária; sem pobreza, reduzindo, gradativamente, asdesigualdades sociais existentes e protegendo o meio ambiente. No entanto, em muitos países, como no Brasil, a aplicação dessas políticas não é realmente efetiva, principalmente no que concerne ao respeito ao direito fundamental a uma moradia livre de riscos à saude. O que sevê no dia a dia, são inúmeras familias morando sobre áreas contaminadas ou, simplesmente, sofrendo consequências nefastas ao seu direito ao meio ambiente sadio, por serem vizinhas de grandes indústrias, em uma violação clara aos princípios preliminares proclamados por esses Estados de Direito. Diante disso, o objetivo principal desse trabalho é o de compreender aimportância da gestão dos solos poluídos, a partir da adoção da política de sua reabilitação. Quanto mais desenvolvida for à legislação sobre a reabilitação das áreas poluídas, quanto melhor for o mecanismo de controle das áreas poluídas ou pontencialmente poluidas, menorserá o risco de que a população venha a viver nessas áreas, ou aos arredores delas, o que consequentemente, favorecerá a promoção de um meio ambiente sadio para todos, favorecendo o surgimento de uma sociedade pautada nos princípios da justiça ambiental.Como metodologia, utilizaremos a abordagem do direito comparado, a fim de demonstrar aevolução do direito fundamental ao meio ambiente na França e no Brasil e estudar alguns casos de poluição dos solos nos dois países. Esta escolha se baseia no fato da França, país industrializado, possuir já, uma certa, tradição no controle das áreas poluídas ou potencialmente poluídas. Ao contrário do Brasil, país em desenvolvimento, que está aind atentando implantar mecanismo para o conhecimento dos seus solos e para a implantação deum sistema de inventário. Dessa forma poder-se-á compreender a importância da legislação ambiental e dos mecanismos de controle da administração pública, para realmente assegurar o respeito ao direito fundamental ao meio ambiente para a população de cada um desses países. Adicionalmente, passamos a avaliar o aspecto sócioeconômico dos casos brasileiros, a fim de compreender a relação entre a poluição dos solos e a injustiça ambiental neste país. Concluíndo, que de um ponto de vista jurídico, não existe, ainda, uma relação entre a poluiçãodos solos ocasionada pela atividade industrial e as desigualdades sociais presentes em umpaís.
3

Investigation to enhance the performance of evaporative spray cooling within Tair cycle refrigeration and air conditioning systems

Hamlin, Stephen January 2000 (has links)
No description available.
4

An investigation into the spatio-temporal patterns of modelling SO2, NOx and surface O3 across the Highveld priority area, South Africa

Roffe, Sarah Jane January 2017 (has links)
A thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfillment of the requirements for the degree of Master of Science. Johannesburg, 2017. / The Highveld is identified as an air pollution ‘hotspot’ area where pollutant concentrations are elevated due to the high density of industrial and non-industrial air pollution sources. To enhance air quality across the Highveld, it was declared a priority area to manage and monitor pollutants to reduce their negative impact on the environment and society. Hence, the aim of this study was to investigate ambient air pollution across the Highveld Priority Area (HPA), using ground-level SO2, NOx and surface O3 concentrations, meteorological parameters and Moderate resolution imaging spectroradiometer (MODIS) atmosphere products, for January to December 2011, to develop new modelling techniques to aid in the management of air pollution. Results show the annual mean trace gas concentrations of SO2, NOx and surface O3 were 12.14, 14.75 and 28.77 ppb, respectively. SO2 and NOx concentrations were highest during winter at an average of 17.56 and 20.96 ppb, where surface O3 concentrations were highest during spring at an average of 32.82 ppb. Diurnal patterns of SO2 and surface O3 were similar, where a midday peak occurred. NOx concentrations instead showed peaks during traffic hours. Ambient air temperature, solar radiation, relative humidity, wind speed and rainfall levels peaked during summer. Atmospheric pressure was relatively stable throughout the year. Winds typically ranged from N to E up to April and from S to NW from May. Very little variation in SO2 and NOx concentrations was explainable by meteorology, 4 to 29 % and 5 to 23 %, while the influence of meteorology on surface O3 concentrations was more significant, 23 to 53 %. Spatial multiple regression statistical models using a cross validation approach for model validation were made over a number of temporal scales. The model fitting and validation processes indicated that the models were not a good fit as only up to 69, 74 and 58 % of SO2, NOx and surface O3 concentrations with high root means square error (RMSE) values of up to 22.10, 15.56 and 18.59 ppb, respectively, could be explained by the models. This process revealed the potential to model pollutants across the HPA, and as a pilot study future work can be based on this study. It is clear that spatial modelling for pollution estimation and management is necessary as seen by the frequent exceedances of the national and international ambient air quality standards. / XL2017
5

A rationale for the effective management of outdoor information transfer

Jordaan, Pieter Francois 21 July 2005 (has links)
This study has a dual purpose. Firstly, it is aimed at determining the need for the effective management of outdoor information transfer as an important resource in the aesthetic environment. Effective management is seen as an optimisation of the benefits of outdoor information transfer, as well as a minimisation of its negative impacts. Secondly, this study was aimed at providing user-friendly guidelines to achieve this. The South African Manual for Outdoor Advertising Control (SAMOAC) was developed in 1998 as a national guideline document to provide detailed conditions for the management and control of outdoor advertisements and signs. This manual recognises the differences in local needs and circumstances and suggests that controlling authorities should adapt the prescribed conditions in this regard. Up till now this document has not been implemented successfully by the relevant controlling authorities. Outdoor advertisements of all sizes are increasing at an alarming rate in South Africa to the detriment of the perceptual environment and tourism resources. One of the most obvious reasons for this is the lack of motivation amongst the controlling authorities together with the persistency of the outdoor advertising industry. This study provides the necessary motivation for involving controlling authorities, the outdoor advertising industry and the public in the meaningful and sustainable management of outdoor information transfer. It looks at the benefits and impact of outdoor information transfer in a holistic manner by taking the variety and interrelationship of such impacts and benefits into consideration. Most previous studies have only concentrated on a single aspect of outdoor information transfer namely the correlation between billboards and road accidents. A key finding of this study is that the effective management of outdoor information transfer is unnegotiable. A laissez faire approach by controlling authorities and self-control by the outdoor advertising industry will lead to visual chaos. A balanced and responsible approach should be followed in managing outdoor information transfer. Outdoor advertising should never be aimed at utilising and maximising every available advertising opportunity and implementing whatever is technologically achievable at the cost of the perceptual environment. The effective management of outdoor information transfer is in the interest of both the perceptual environment and the outdoor advertising industry. It has been found that sense of place and placeness play an important role with regard to the impacts and benefits of outdoor information transfer. The lack of sufficient environmental ethics in Western society has been identified as an underlying problem. A non-pragmatic environmental world-view has therefore been provided based on Christian axioms to serve as a basis for environmental management including perceptual resource management and the management of outdoor information transfer. In order to actualise the need for the effective management of outdoor information transfer general principles and user-friendly guidelines are provided that will be universally applicable. It will make the management of outdoor information transfer less subjective and will serve as a basis for legislative and control measures. These principles and guidelines are flexible enough to accommodate a variation in local conditions, lifestyles and aspirations. It can therefore serve as an instrument to adapt SAMOAC to suit local circumstances and needs. The recommendations provided in this study are aimed at creating an appreciation for the perceptual environment as well as the role and aesthetic contribution of outdoor advertisements and signs. It is also aimed at involving the public, controlling authorities and the outdoor advertising industry in the sustainable management of outdoor information transfer as an important part of the perceptual environment. / Thesis (PhD (Regional Planning))--University of Pretoria, 2006. / Town and Regional Planning / unrestricted
6

De l'organisation du vivant aux assemblages fossiles : comparaison des communautés de bivalves modernes et anciennes

Doitteau, Gaelle 20 December 2012 (has links)
La thèse s'intéresse à l'enregistrement des propriétés de la biodiversité dans les archives sédimentaires. Elle s'appuie sur l'analyse d'une faune contemporaine de milieu tropical, collectée dans le Lagon de Touho, Nouvelle-Calédonie lors de l'expédition Montrouzier en 1993. Les différences de diversité entre les assemblages de bivalves vivants et de coquilles mortes d'un même site sont quantifiées à l'aide de plusieurs descripteurs (richesse taxonomique, indice PIE d'eveness, courbes de raréfactions, indices de fidélité) et d'outils de classification (analyses Cluster, NMDS). Les associations d'espèces vivantes varient dans l'espace en fonction de paramètres environnementaux comme le type du substrat ou la profondeur. La composition des assemblages morts diffère des écosystèmes vivants, mais ils conservent globalement les informations environnementales. Les assemblages morts sont en général plus diversifiés que les communautés vivantes associées, à cause de l'accumulation de nombreuses espèces rares. Cet enrichissement s'explique par : 1) la préservation des coquilles autochtones, 2) l'apport de coquilles allochtones et 3) la condensation du temps. Des différences de fidélité entre les communautés biologiques et les assemblages de coquilles mortes apparaissent en fonction des environnements. Par exemple, les environnements à substrat induré sont associés à une mauvaise préservation des communautés vivantes, contrairement aux environnements profonds qui conservent bien les espèces autochtones mais accumulent beaucoup d'espèces allochtones. / The thesis explores how the properties of biodiversity are preserved in the sedimentary archives. Discussions are supported by the analysis of the modern tropical fauna of the Touho Lagoon (New Caledonia), collected during the Montrouzier expedition in 1993. The differences between live bivalve assemblages and dead shell assemblages are quantified with various indices (taxonomic richness, PIE index of evenness, rarefaction curves, fidelity indices) and classification tools (Cluster analyses, NMDS).Environmental parameters, such as the type of substrate or the water-depth, are responsible for variations among live species associations. The composition of dead shell assemblages differs from the living communities but environmental informations arepreserved. Generally, the dead shell assemblages are more diversified than live fauna of the same sites because of the accumulation of rare species. The higher diversity of dead shell assemblages can be explained by 1) the preservation of autochthonous bivalve shells, 2) the input of allochthonous shells and 3) the time-averaging. The fidelity of dead shell assemblages to the biological communities varies according to the environmental conditions. For example, dead shell assemblages found on hard substrate environments may be very different from the living communities. Allochthonous species tend to accumulate in deep outer shelf environments... Salinity, substrate or water-depth are main perturbation factors, as they imply loss or gain of taxa.The preservation of living communities varies according to the biological caracteristics, such as ecology, population structure or shells mineralogy.
7

Ambient air quality monitoring : a comparison between two urban parks in Soweto, South Africa

Valsamakis, Sophia Katerina January 2016 (has links)
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. 14 August 2015 / Soweto is identified as an air pollution hot spot area which is characteristic of poor air quality where ambient air pollutant concentrations frequently exceed the South African Ambient Air Quality Standards. Urban greening programmes are seen as a way for cities to work towards reducing air pollution, offsetting greenhouse gas emissions and improve ambient air quality. The City of Johannesburg embarked on the Greening Soweto project in 2006 where many degraded open spaces were transformed into urban green parks and 6000 trees were planted. The urban parks and trees are believed to serve several environmental benefits; one of which includes the improvement in local ambient air quality. The aim of this research was to assess and compare the local ambient air quality situation at two different urban park types in close proximity, Thokoza Park (older trees) and Petrus Molefe Eco-Park (young trees), in Soweto and establish whether the air pollutants measured at the urban parks were lower compared to the urban background conditions. Furthermore, this study assessed whether the ambient concentrations of the selected criteria air pollutants were within the South African National Ambient Air Quality Standards. Three ambient air quality monitoring campaigns were conducted during the spring (October) and winter (June and July) seasons of 2013 and 2014 with the use of a mobile air quality monitoring station. The findings of this research suggest that urban trees in Thokoza Park and Petrus Molefe Eco-Park has the greatest potential to improve air quality in Soweto mainly through changes in local meteorological conditions, specifically for temperature and wind fields, rather than direct removal of air pollutants. Differences in the concentrations of the air pollutants at the different sites showed a strong relationship with changes in temperature, wind speed and direction and emission source types. A significant difference in air pollutant concentrations between the two urban park types was only found for particulate matter (PM10 and PM2.5) and CO2. In general, lower air pollutant concentrations were recorded at the urban parks compared to the urban background site, particularly during the spring season. This study also suggests that the urban trees could represent a potential O3 sink during the spring and winter seasons and for NOx during the spring season. Exceedances of the South African Ambient Air Quality Standards at the two urban parks were only observed for PM10 and PM2.5 during the winter season of 2014. PM10 and PM2.5 and NOx were identified to be air pollutants of concern at the urban parks in comparison to other criteria air pollutants assessed in this study. Maximum daily concentrations of 255 μg/m3 for PM10 and 126 μg/m3 for PM2.5 and a maximum hourly concentration of 92 ppb for NOx were recorded at the parks during winter season
8

Experimental analysis of infectious passenger isolation system for aircraft

Darrah, Ian David January 1900 (has links)
Master of Science / Department of Mechanical and Nuclear Engineering / Mohammad H. Hosni / Byron W. Jones / Limiting the spread of infectious airborne diseases and airborne pathogens is an important consideration in aircraft environmental control system design. However, when a passenger suspected of having a highly contagious disease or very dangerous disease is identified in flight, it is desirable to further isolate the individual from other passengers. A research project was conducted to explore an isolation system that can be stored in a small space and deployed in flight if needed. This device is referred to as an “Expedient Passenger Isolation System” abbreviated as ISOPASS. The ISOPASS is a portable, negative-pressure isolation system that can be installed over a section of seats quickly by a flight attendant during flight. A prototype proof of concept ISOPASS was evaluated in this study. Measurements were conducted in a full-scale, 11-row mock-up of a wide-body aircraft cabin, as well as a 5-row section of a narrow-body aircraft cabin. Heated mannequins to simulate the thermal load of passengers inside the cabin were seated in the mockup. Carbon dioxide was used as a tracer gas and was mixed with helium to maintain neutral buoyancy in air. The tracer gas was used to simulate airborne pathogen spread and was injected at the breathing level at a seat within the ISOPASS. Tests were conducted with and without the ISOPASS in place. Matched pairs were used to mitigate potential statistical problems. Matched pair tests were completed with gaspers turned on and off. Measurements were repeated three times for each gasper setting and for each ISOPASS condition. Concentration measurements were taken at the breathing level inside the ISOPASS at the seat next to the injection source; at the seat across the aisle adjacent to the ISOPASS; and at a seat far away from the ISOPASS near the front of the cabin. The with- and without-ISOPASS matched pair tests clearly show the ISOPASS prototype is highly effective at providing isolation in each aircraft cabin used in the study. Additionally, it was determined that the use of gaspers makes no measurable difference in the containment effectiveness of the ISOPASS.
9

Building Environmental Control Simulation

Cordahi, Charles Khalil 10 1900 (has links)
<p> The general purpose of this work is to study the feasibility of using McMaster University's PACER and MACSIM Executive Computer Programmes to simulate the environmental control system in a large building by means of elementary modules. </p> <p> The operation of PACER is described together with some general instructions as to its use. </p> <p> A number of module subroutines are developed, covering a wide cross-section of the type of equipment used in the air conditioning, heating and ventilation of a building. They are used in various combinations within the main programme to demonstrate their use. The programmes developed are not sufficient to simulate a complex system; however, they would act as a guide to the user for developing the necessary programmes to enable him to represent almost any type of equipment. </p> / Thesis / Master of Engineering (ME)
10

Understanding independent environment control officers : learning from major South African construction projects / Johannes Albertus Wessels

Wessels, Johannes Albertus January 2015 (has links)
An independent industry of Environmental Control Officers (ECOs) is active on various construction sites across South Africa. It forms part of a global network of verifiers, such as Environmental Impact Assessment (EIA) and EIA follow-up verifiers. This network authenticates statements about and the implementation of sustainability commitments made during the planning phase of major construction projects. International studies show that the construction industry is experiencing many challenges to deliver sustainability commitments, including inadequate collaboration between role players, illdefined roles and responsibilities, and insufficient use of environmental governance approaches. On-site verifiers like ECOs may aid in restraining these challenges by bridging ineffective governance approaches, such as classic EIA with new governance approaches, for instance self-responsibility (e.g. Environmental Management Systems (EMSs)) and involvement of third parties. Moreover, an “independent from all” verification function may be vital in developing countries such as South Africa, where trust between the government, market and public is particularly fragile due to historical injustices. Interestingly, limited learning has been drawn and shared from this function’s real-world experience. There are also differing views on the role, independence and value of ECOs, due to roles, frequent interaction with persons responsible for delivering sustainability commitments, and collaboration with third parties being ill-defined. The overarching purpose of this study is to advance understanding of independent ECOs in major South African construction projects. Three lines of inquiry are followed. The first is to define what the role is, or ideally should be, of an ECO in the South African compliance monitoring and enforcement effort. The second is to identify what factors might influence the independence of verifiers. The third is to appraise how and to what extent independent EIA follow-up verifiers add value in major construction projects in the developing country context of South Africa. This study’s research assumptions are based on the real world of ECOs and uses a mixed method research approach to draw knowledge from the industry. The strategies of inquiry include a survey, interviews, and multiple case study evaluations. The methods for data collection include literature review, a self-administered survey questionnaire, semi-structured interviews, video material, observations of practice at case studies, and the collection of project documentation. The methods used for data analysis are the categorisation and measuring of opinions and statements of survey participants, the analysis of video material and project documentation, and the nominal categorisation and ordinal scaling of case study results. Three journal articles capture the essence of the research results and form part of the thesis report, as prescribed by the North-West University’s rules for doctoral theses in article format. All three articles were peer-reviewed and published in journals aimed at international audiences. Article 1 of the thesis highlights that an industry of ECOs fulfils numerous roles at various construction sites across South Africa. The results identify the importance of ECOs functioning independently of all role-players, but warn that obsessing about independence may compromise the ability of ECOs to fulfil their roles. The results also show that industry is in need of competence and the regulation thereof, as well as support from all role players. By drawing from the research results, the thesis defines an ECO. Article 2 of the thesis reiterates that independence is central to internationally acclaimed verification fields and important to ensure the credibility of EIA. The study identifies 18 factors that might influence the independence of EIA follow-up verifiers and divides the factors into five categories: financial, commercial, professional, personal, and other. By identifying and sharing these factors, this thesis aids in anticipating and avoiding potential conflict of interest between environmental role players. Article 3 strengthens the continuum between environmental governance approaches by conceptualising a framework for appraising the value of independent EIA follow-up verifiers. The framework provides for inter-linking principles and objectives of sustainability to the performance areas of EIA, EIA follow-up and the EMS. The appraisal results indicate that independent verifiers add most value when they are involved in screening, checking compliance, influencing decisions, community engagement, and integrating environmental governance approaches. The study confirms the benefits of adaptable, proactive, experienced, and independent EIA follow-up verifiers, such as ECOs, on major South African construction projects. / PhD (Geography and Environmental Management), North-West University, Potchefstroom Campus, 2015

Page generated in 0.1122 seconds