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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.
11

Hodnocení způsobů výsadeb dřevin na degradovaných půdách v oblasti Awassa Zuria Woreda v jižní Etiopii

Pangrác, Jan January 2018 (has links)
The aim of this diploma thesis is tree planting method comparison of water retention improving technology (Improve pits) and non-improving technology (Pits). Research was realized on the „Sustainable management of soil, forest and water resources as the pilot model for the rural development in SNNPRS, Ethiopia“ project areas. This project was realized by Mendel university in Brno. Terrain investigations, experimental plot set up and soil sample collection and analyses were realized by devised methodology. Terrain works took a place during July and August 2016. When comparing resulting values, it became clear that the Improve pits technology shows positive effect on soil water retention capacity and its gradual release. This effect creates more suitable conditions for regeneration of damaged vegetation.
12

Estudo da codisposição de resíduos de fossas e tanques sépticos, com e sem a remoção prévia de gordura, no desempenho de tratamento de esgoto com reatores UASB / Codisposição study of waste and seotic tanks e repair, with and without prior removal of fat in the performance of sewage treatment with UASB reactors

Peixoto, Aline Vieira 15 July 2013 (has links)
Submitted by Jaqueline Silva (jtas29@gmail.com) on 2014-12-08T18:01:37Z No. of bitstreams: 1 Dissertação-Aline Vieira Peixoto-2013.pdf: 3799528 bytes, checksum: 6a3b319d28bdad78b71d1bd2920717de (MD5) / Rejected by Jaqueline Silva (jtas29@gmail.com), reason: on 2014-12-08T20:24:04Z (GMT) / Submitted by Jaqueline Silva (jtas29@gmail.com) on 2014-12-12T19:33:30Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação-Aline Vieira Peixoto-2013.pdf: 3799528 bytes, checksum: 6a3b319d28bdad78b71d1bd2920717de (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2014-12-16T09:22:47Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação-Aline Vieira Peixoto-2013.pdf: 3799528 bytes, checksum: 6a3b319d28bdad78b71d1bd2920717de (MD5) / Made available in DSpace on 2014-12-16T09:22:49Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação-Aline Vieira Peixoto-2013.pdf: 3799528 bytes, checksum: 6a3b319d28bdad78b71d1bd2920717de (MD5) Previous issue date: 2013-07-15 / In Brazil, according to a national survey conducted by the Brazilian Institute of Geography and Statistics (IBGE, 2010), 44.8% of the municipalities use simplified domestic waste treatment systems such as septic tanks, rudimentary cesspools and dry pits. Such systems lead to the production of potentially polluting waste which requires suitable co-treatment. Several co-treatment alternatives have been proposed. The present study, which is part of the Program on Basic Sanitation Research (PROSAB), aimed to evaluate the interference caused by septage disposal from cesspools and septic tanks on the performance of the Upflow Anaerobic Sludge Blanket Reactor (UASB) in the city of Itumbiara- Goiás. The study took nine months and was divided into three distinct phases, in which the volumetric flow rate of wastewater from cesspools and septic tanks into the reactor ranged from 0.17% to 0.51%, displaying an intermediate phase of 0.34%.In the third phase, another fat flotation phase was added to the pre-treatment prior to discharge. During the study, we utilized all the waste volume from cesspools and septic tanks produced by the municipality and discharged into the Itumbiara Wastewater Treatment Plant (WWTP), already working at its full capacity. Statistical tests have proved that wastes from cesspool and septic tanks disposed into UASB reactors showed no significant difference in the final effluent quality. It was not evidenced also significant differences in the operation and maintenance of the reactors. The biological sludge from the UASB reactors got stable after being added the wastes (ratio VS/TS between 0.53 and 0.58 average). The receiving reactor’s begs had a worse efficiency but statistical tests showed that the difference was not significant when compared to the control reactors. It was observed in this study, there is no need for the pre-flotation of waste before being released at WWTP with UASB system. Thus the UASB is a viable alternative, but it is necessary to follow a protocol to establish criteria such as the waste application rate, the WWTP site for waste discharge, physical structure and people, as well as to choose for relevant parameters for the waste monitoring before co-treatment. / No Brasil, segundo Pesquisa Nacional de Saneamento Básico do Instituto Brasileiro de Geografia e Estatística (IBGE, 2010), 44,8% dos municípios utilizam sistemas simplificados para tratamento dos esgotos domésticos como: tanques sépticos, fossas rudimentares, fossas secas. Estes sistemas têm como consequência a produção de resíduos com potencial poluidor que necessitam de codisposição adequada. Diferentes alternativas de codisposição têm sido propostas. O presente trabalho, inserido na rede de pesquisa do Programa de Pesquisas em Saneamento Básico (PROSAB), tem como objetivos avaliar as interferências da disposição de resíduos de fossas e tanques sépticos no desempenho do Reator Anaeróbio de Manta de Lodo de fluxo ascendente ou Upflow Anaerobic Sludge Blanket (UASB), na cidade de Itumbiara-Goiás. O estudo teve duração de nove meses e foi dividido em três fases distintas, alterando a taxa de aplicações volumétrica dos resíduos de fossas e tanques sépticos no reator que variou de 0,17% a 0,51%, tendo uma fase intermediária de 0,34%, além de, na terceira fase, acrescentar mais uma etapa de flotação da gordura no tratamento preliminar, antes do lançamento dos resíduos. Durante a pesquisa, foi utilizado todo o volume de resíduos de fossas e tanques sépticos gerados pelo município e dispostos na ETE de Itumbiara que já trabalha com a carga máxima. Testes estatísticos comprovaram que a disposição de resíduos de fossas e tanques sépticos nos reatores UASB não apresentou diferença significativa na qualidade do efluente. Também não foram comprovadas alterações significativas na operação e manutenção dos reatores. O lodo biológico dos reatores UASB apresentou estabilidade após a disposição dos resíduos (relação SV/ST entre 0,53 a 0,58 em média). Os leitos do reator receptor apresentaram pior eficiência, porém testes estatísticos comprovaram que a diferença não foi significativa quando comparado com reatores testemunhos. Foi observou neste estudo, que não há necessidade da flotação prévia dos resíduos antes de serem lançados nas ETEs com sistema UASB. Portanto o UASB é uma alternativa viável, porém é necessário seguir um protocolo com critérios que estabelecerá a taxa de aplicação dos resíduos, o local na ETE onde será lançado o resíduo, estrutura física e de pessoal da ETE e determinar parâmetros de relevância para o monitoramento dos resíduos antes da codisposição.
13

Runoff Reduction Benefits of Retrofitted Enhanced or Extended-Depressed Tree Pits of the Beasley and Landsdale Neighbourhoods in Hamilton, Ontario

Rawlins, Robert January 2019 (has links)
This research explores the potential of retrofitting enhanced or extended-depressed tree pits (ETPs/EDTPs) around existing street trees to bolster pre-development hydrological processes in two Hamiltonian neighbourhoods to help satisfy their social, economic, and environmental needs and work toward the Sustainable Development Goals (SDGs). Using QGIS and openly available data to create catchment areas, establish the feasibility of a 20:1 catchment to pit area ratio, and investigate the performance of five available structured soil cells, the innovative Analytical Probabilistic Model (APM) for Bioretention systems was adapted to conduct a parametric sensitivity analysis and subsequently compute the Road Runoff Reduction Efficiency (RRRE) of the designs under different climatic scenarios. The catchment to pit area ratio, design storage depth, and final infiltration rate were found to have a significant impact on the RRRE while the average evapotranspiration rate did not. Based on a 75% efficiency cut-off, and assuming a 20:1 catchment to pit area ratio, the shallowest two depths were deemed ineffective in all final infiltration rate scenarios while the largest depth provided efficiencies greater than 75% runoff reduction even when faced with the lowest rate of 6 mm hr-1. Comparing the RRRE during current climatic conditions to a simulated 2050s winter suggests that the RRRE of the deepest implementation is impacted only half as much as the shallowest; larger systems are more resilient. This research has reinforced the versatility and efficiency of the Analytical Probabilistic Model for modeling system performance of LIDs and ETPs, supports the prominent findings of the efficacy of enhanced tree pits to significantly contribute to urban stormwater management and re-establish more natural and sustainable hydrologic processes, and promotes them as a key to reaching the SDGs in Hamilton, Ontario. / Thesis / Master of Applied Science (MASc) / The Sustainable Development Goals call for action from every member of society. This research explores the potential Stormwater Management Engineers have to do so by retrofitting street trees with Enhanced or Extended-Depressed Tree Pits, increasing rooting volume and offering the tree more water from the adjacent road to simultaneously meet the natural needs of the tree and reduce urban runoff.
14

Impact assessment of the effectiveness of the Public Internet Terminals Infrastructure Model: SAPO

Matsena, Portia 30 August 2012 (has links)
The Public Internet Terminal (PIT) is the Department of Communication initiative that aims to bring electronic communication to all South African citizens. It was launched in 1998 as a joint venture between the Department of Communications (DoC) and the South African Post Office (SAPO).This study postulates that the massive roll out of the Public Internet terminals (PIT‘s) has enhanced the lives of the poor by providing easy access to government services. It further assumes that the PITs are able to facilitate access of eService‘s to all the citizens in particular where electronic services are not freely available such as in the rural and remote under serviced areas of South Africa. In addition, it explores the envisaged value added initiatives stipulated in the memorandum of understanding entered in between the Department of Communication (DOC) and the South African Post Office (SAPO).
15

Influência do tempo de extração e da razão amostra: solvente no processo de extração do óleo do caroço do pequi visando a produção de biodiesel

Oster, Vanessa Viebrantz 22 April 2013 (has links)
Problemas ambientais causados pelo uso excessivo de energia proveniente do petróleo estão fazendo com que os países busquem a diversificação da matriz energética. Dentro deste contexto, é que a produção de biodiesel, a partir de óleos vegetais, vem se destacando no cenário energético. A extração da matéria-prima usada na produção desses biocombustível é uma fase de extrema importância, por isso, faz-se necessário determinar qual a melhor forma de sua realização, caracterizando os principais fatores químicos e físicos que interferem nesse processo. Visando otimizar o processo de extração do óleo do caroço do pequi, este trabalho baseou-se na realização de experimentos que buscaram identificar o teor aproximado de óleo no caroço do pequi e ainda qual o melhor solvente orgânico, entre hexano, etanol e a mistura desses solventes, para a extração do óleo do caroço do pequi para a produção de biodiesel. A partir dos dados obtidos nos ensaios realizados neste trabalho, pode ser observado que o putâmem do pequi apresenta um teor elevado de óleo, em méidia de 31%, quantidade superior a encontrada no grão da soja, que hoje é a matéria – prima base para a produção de biodiesel. Observou-se ainda que a misturas dos dois solventes orgânicos (hexano + etanol) na razão de 1:1 mostrou-se mais eficiente no processo extraíndo aproximadamente 34% do óleo presente no caroço do pequi. / The environmental problems caused by the excessive use of energy from petroleum are causing countries seek to diversify sources of energy. Within this context, is that the production of biodiesel from vegetable oils, has been increasing in energy scenario. The extraction of the raw material used in producing these biofuels is an extremely important step, so it is necessary to determine the best form of his achievement, featuring the main chemical and physical factors that affect this process. In order to optimize the extraction process of oil pits pequi, this work was based on the realization of experiments that attempted to identify the approximate oil content in the pits pequi and yet which is the best organic solvent, hexane between ethanol and the mixture of these solvents for oil extraction from the seed pequi for biodiesel production. Starting from the data obtained in the tests performed in this study, it can be observed that the pits pequi has a high content of oil, around 31%, much higher than found in soy beans, which today is raw - material basis for biodiesel production. It was also observed that mixtures of two organic solvents (hexane + ethanol) at a ratio of 1:1 was more efficient in the process of Extracting approximately 34% of the oil present in the pits pequi.
16

Impact assessment of the effectiveness of the Public Internet Terminals Infrastructure Model: SAPO

Matsena, Portia 30 August 2012 (has links)
The Public Internet Terminal (PIT) is the Department of Communication initiative that aims to bring electronic communication to all South African citizens. It was launched in 1998 as a joint venture between the Department of Communications (DoC) and the South African Post Office (SAPO).This study postulates that the massive roll out of the Public Internet terminals (PIT‘s) has enhanced the lives of the poor by providing easy access to government services. It further assumes that the PITs are able to facilitate access of eService‘s to all the citizens in particular where electronic services are not freely available such as in the rural and remote under serviced areas of South Africa. In addition, it explores the envisaged value added initiatives stipulated in the memorandum of understanding entered in between the Department of Communication (DOC) and the South African Post Office (SAPO).
17

A Functional Approach to Resolving the Biogeocomplexity of Two Extreme Environments

Rubelmann, Haydn, III 12 November 2014 (has links)
The biodiversity of two distinct marine environments was observed to describe the biogeocomplexity of these extreme ecological systems. A shallow-water hydrothermal vent in Papua New Guinea served as a study of a thermophilic ecosystem influenced by arsenic rich vent fluids while a 60 m deep offshore primarily anoxic karst sink served as a study of an anaerobic sulfur-influenced habitat. Both environments support unique biological communities that are influenced by the physical and chemical pressures imposed on them by the harsh conditions of these systems. In Tutum Bay, Ambitle Isle, Papua New Guinea, a transect was created from a shallow hydrothermal vent that extended 120 m away from the vent. Previous studies have shown that the geochemistry of the system is heavily influenced by arsenic which is toxic to most organisms. In this study, macro- and meiofauna were collected and scored and combined with bacterial sequence data collected along the length of the transect. It was found that near vent sites harbored biological communities more similar than sites further from the vent. Many species were found only at sites near the hydrothermal vent. Near-vent communities were less diverse than those away from the vent, and biodiversity generally increased as distance from the vent increased. Distinct correlations between thermophilic organisms and temperature were observed. The metabolic repertoire of the microbial communities suggests that many strategies are used to obtain energy and carbon. The relative abundance of bacteria containing genes to reduce arsenic was comparable to those able to reduce sulfur compounds. Primary production appeared to be a mix of chemo- and phototrophy. Food webs and association analysis suggest a complex interplay between macrofaunal, meiofaunal and bacterial communities. While the system is heavily influenced by arsenic, no specific correlation between the relative abundance of arsenic metabolizing organisms and the amount of arsenic in the system could be drawn. This is likely due to the fact that most of the arsenic produced by the system is readily adsorbed onto iron oxyhydroxides, reducing the arsenic's bioavailability. The anoxic conditions at Jewfish sink provide a different hurdle than the hot arsenic conditions found in Papua New Guinea. The anoxic conditions are shared by other pit features found in karst geography, but the metabolic processes between Jewfish sink and these other karst habitats are different. The blue holes and black holes of the Bahamas are some of the most well-studied of these karstic pits. In these features, which are large circular pits with diameters of over 300 m, light and sulfur are used as a means of energy acquisition. Jewfish sink, having an opening only 6 m in diameter, is light restricted compared to these systems. As a result, the strategy of organisms dwelling in the anoxic conditions of the sink is different than those found at the well-studied holes in the Bahamas. Geochemical measurements were recorded over two time periods spanning a combined total of 6 years. The anoxic bottom waters of Jewfish sink remain stable and contained high levels of sulfide throughout most of the seasons studies. Sequence analysis of prokaryotes within the sink showed that sulfur reducers had the highest relative abundance compared to other functional guilds. To monitor the changes of the microbial communities within the sink, bacterial communities were examined at 4 depths within the sink at 9 different intervals over a period of 685 days. Denaturing Gradient Gel Electrophoresis (DGGE) was used to fingerprint 16s rRNA bacterial communities and dissimilatory sulfite reducing communities by targeting the 16s rRNA bacterial gene and the dsr gene associated with dissimilatory sulfite reducing bacteria and archaea. The lowest depth studied within the sink (40 m) remained stable chemically and biologically until a turnover event occurred within the second winter of the study. This turnover event disrupted the biological communities at 40 m and led to a reestablished community comprised of different species that those found prior to the event. Upper waters within the sink show that clines establish themselves seasonally and partition zones that confine bacterial communities that are more similar to each other within these zones while excluding bacterial communities that are outside of these zones. Oxygenated water was shown to not contain prokaryotes containing the dsr gene. As the oxycline changed seasonally, dissimilatory sulfite reducing prokaryotes containing the dsr gene remained in the anoxic zone and required time to reestablish themselves whenever oxygenated water displaced them.
18

Graded InGaN Buffers for Strain Relaxation in GaN/InGaN Epliayers Grown on Sapphire

Song, T.L., Chua, Soo-Jin, Fitzgerald, Eugene A. 01 1900 (has links)
Graded InGaN buffers are employed to relax the strain arising from the lattice and thermal mismatches between GaN/InGaN epilayers grown on sapphire. The formation of V-pits in linearly graded InGaN/GaN bulk epilayers is illustrated. The V-pits were sampled using Atomic Force Microscopy and Scanning Electron Microscopy to examine their variation from the theoretical geometry shape. We discovered that the size of the V-pit opening in linearly graded InGaN, with and without GaN cap layer, has a Gaussian distribution. As such, we deduce that the V-pits are produced at different rates, as the growth of the InGaN layer progresses. In Stage I, the V-pits form at a slow rate at the beginning and then accelerate in Stage II when a critical thickness is reached before decelerating in Stage III after arriving at a mean size. It is possible to fill the V-pits by growing a GaN cap layer. It turns out that the filling of the V-pits is more effective at lower growth temperature of the GaN cap layer and the size of the V-pits opening, which is continued in to GaN cap layer, is not dependent on the GaN cap layer thickness. Furthermore, graded InGaN/GaN layers display better strain relaxation as compared to conventionally grown bulk GaN. By employing a specially design configuration, the V-pits can be eliminated from the InGaN epilayer. / Singapore-MIT Alliance (SMA)
19

Möjlig bronsåldersboplats? : en undersökning av platser från bronsåldern på Gotland / Possible Bronze Age Settlement? : a study of places from Bronze Age on Gotland

Sardén Johansson, Erika January 2010 (has links)
<p>There are none known Bronze Age settlement on Gotland, although there are severalexcavation reports that mention that they have found a probable Bronze Age settlement. In the excavation that have been done in the study areas, there are Bronze Age dated hearths, cooking pits and post holes. These study areas have been investigated if they might be possible Bronze Age settlements. This paper discusses about the criteria of settlements and also investigate if the study areas meet those criterias. There are many different criteria for settlement but only the criteria of FMIS are used in the study. There are also different criteria for hearths and cooking pits, what separates them from each other. There have been measures on the distance between different landscape variables in the study areas to see if there are any differences or similarities between the different study areas.</p>
20

Relationships between water quality, species composition, biodiversity and ecosystem function in lakes and flooded pits exposed to uranium mining activities in Northern Saskatechewan

Helps, Devin Murray 25 May 2009
Uranium mining activities have the potential to impact aquatic systems through mine drainage (runoff) and the release of treated effluent into nearby watersheds. Such anthropogenic exposure can lead to elevated concentrations of metals and major ions, which may impact aquatic biota. Previous studies have looked at the effects of water quality on aquatic biota within flooded pit lakes and natural lakes that have been exposed to various mechanisms of mining exposure. However, the literature often only examines the effects of a limited number of contaminants on a limited number of species. Researchers have rarely looked at the effects of multiple contaminants on species composition, biodiversity and ecosystem function in aquatic systems. This study uses a multivariate approach to look for relationships between water quality (24 variables), plankton species composition and abundance, biodiversity (richness and evenness) and ecosystem function among lakes exposed to mining activities (n = 18) and non-exposed reference lakes (n = 8). Lake water quality data was used to cluster lakes into groups. Lake groups were then overlain onto multivariate ordinations derived from species composition-abundance data to determine if species composition was related to water quality. Ecosystem function variables included planktonic phosphorus cycling and planktonic respiration. The classified lake groups clustered well on ordinations derived from species composition-abundance data suggesting that relationships exist between water quality and plankton species composition. However, ecosystem function was similar among the majority of lakes and flooded pits despite differences in species richness, species composition and species abundance. Only a small number of aquatic systems had ecosystem function properties that were different from the majority of lakes and pits. These systems had the greatest concentrations of contaminants and had very low biodiversity (richness and evenness) compared to the other systems. Despite having differences in plankton species composition and species richness, all lake groups were functionally similar. This suggests that functional redundancy in species composition may be present in the majority of lakes and pits in such a way that ecosystem function is maintained.

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