• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 95
  • 69
  • 17
  • 10
  • 6
  • 5
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 1
  • Tagged with
  • 240
  • 32
  • 32
  • 23
  • 20
  • 19
  • 19
  • 18
  • 16
  • 15
  • 14
  • 14
  • 13
  • 13
  • 13
  • 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.
81

Extração sequencial aplicada à lama negra de Peruíbe / Sequential extration applied to Peruibe black mud

Jefferson Koyaishi Torrecilha 05 November 2014 (has links)
A Lama Negra de Peruíbe é utilizada em tratamentos terapêuticos, tais como, psoríase, dermatites periféricas, acne e seborreia, além de utilizações em mialgias, artrites e processos reumáticos não articulares. Assim como a demais argilas medicinais ela pode não estar isenta de possíveis efeitos danosos à saúde, sendo os principais, a ocorrência de minerais perigosos ao sistema respiratório e possíveis efeitos devido à presença de elementos tóxicos. Uma vez utilizado com finalidade terapêutica, um material deve ser completamente caracterizado e, desta forma, amostras da lama negra de Peruíbe foram analisadas para determinar suas propriedades físicas e químicas: teor de umidade, matéria orgânica e perda ao fogo; pH, granulometria, capacidade de troca catiônica e grau de inchamento; composição elementar determinada por Análise por Ativação Neutrônica, Absorção Atômica com Forno de Grafite e fluorescência de raios X e composição mineralógica determinada por difração de raios X. Outra ferramenta bastante utilizada para avaliar o comportamento de elementos traço em diversas matrizes ambientais é a extração sequencial. Sendo assim, foi feito um processo de extração sequencial para fracionar a lama em formas geoquímicas específicas e verificar como e em que quantidade os elementos estão contidos nela. Considerando os diversos procedimentos de extração seqüencial, foi utilizado o método BCR-701 (Community Bureau of Reference) por ser o mais reprodutivo entre eles bem como uma extração simples com suor artificial a fim de se avaliar quais elementos estão potencialmente disponíveis para absorção pela pelo do paciente durante um tratamento tópico. Os resultados indicaram que a lama é constituída basicamente por um material silto-argiloso, rico em matéria orgânica e com boa capacidade de troca catiônica. Não foram observadas variações significativas na composição mineralógica e elementar das formas in natura e maturada da lama. As análises por extração sequencial e extração simples indicaram que os elementos que estão eventualmente disponíveis em maior quantidade para serem absorvidos pela pele durante o tratamento são Ca, Mg, Mn e Na. / The Peruíbe Black mud is used in therapeutic treatments such as psoriasis, peripheral dermatitis, acne and seborrhoea, as well as in the treatment of myalgia, arthritis, rheumatism and non-articular processes. Likewise other medicinal clays, it may not be free from possible adverse health effects due to possible hazardous minerals leading to respiratory system occurrences and other effects, caused by the presence of toxic elements. Once used for therapeutic purposes, any given material should be fully characterized and thus samples of Peruíbe black mud were analyzed to determine physical and chemical properties: moisture content, organic matter and loss on ignition; pH, particle size, cation exchange capacity and swelling index. The elemental composition was determined by Neutron Activation Analysis, Atomic Absorption Graphite Furnace and X-ray fluorescence; the mineralogical composition was determined by X-ray diffraction. Another tool widely used to evaluate the behavior of trace elements, in various environmental matrices, is the sequential extraction. Thus, a sequential extraction procedure was applied to fractionate the mud in specific geochemical forms and verify how and how much of the elements may be contained in it. Considering the several sequential extraction procedures, BCR-701 method (Community Bureau of Reference) was used since it is considered the most reproducible among them. A simple extraction with an artificial sweat was, also, applied in order to verify which components are potentially available for absorption by the patient skin during the topical treatment. The results indicated that the mud is basically composed by a silty-clay material, rich in organic matter and with good cation exchange capacity. There were no significant variations in mineralogy and elemental composition of both, in natura and mature mud forms. The analysis by sequential extraction and by simple extraction indicated that the elements possibly available in larger quantities to be absorbed by the skin during treatment are Ca, Mg, Mn and Na.
82

Efeitos da adição de biossólido no crescimento inicial de Eucalyptus citriodora Hook / Effects of the biosolids addition in the initial development of Eucalyptus citriodora Hook

Pérez, Paula Vergili 12 July 2008 (has links)
Made available in DSpace on 2017-07-10T17:37:30Z (GMT). No. of bitstreams: 1 Paula Vergili Perez.pdf: 278645 bytes, checksum: 8f1b598485cd501565227a64c7a9f289 (MD5) Previous issue date: 2008-07-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nowadays the concerns about the high amount of organic material produced by human activities refer to its reutilization. Thus, the usage of treated sewer mud as an organic fertilizer and physical conditioner of soils has been researched for several cultures, especially forest species. Hence this work aimed to evaluate the effects of the addition of biosolids doses in the initial development of the Eucalyptus citriodora Hook. For this experiment it was utilized doses of biosolids equivalents at 0, 10, 20, 30 and 40 t ha-1. With their incorporation to a superficial layer of 20 cm. The parameters evaluated were: plants length; number of leaves, foliar area, colon diameter and aerial and radicular dry biomasses on 60, 120, 180, 240 and 300 days after the transplant. The analysis of the results pointed that the viability of the use is between the doses 30 e 40 t ha -1, because their effects are positively demonstrated in the parameters: plant length (increases average between 30 e 40 t ha-1 equal to 38,85 cm) and number of leaves (increases average between 30 e 40 t ha-1 of 43,9 leaves, higher than other treatments that got an average equal to 35,62 leaves), as well as in the colon diameter and aerial and dry biomass. Evidences on the reduction of the radicular dry biomass accumulation with the application of increasing doses of biosolid, the dose 10 t ha-1 stood out, because this got the average higher (99,12g) than the other treatments (31,48), indicating a priority in the growing strategy of the fast development specie, which commercial interest is emphasized by the production of wood and leaves, implies a recommendation of doses of 30 t ha-1 that is able to reduce expenses in transport and in application comparatively to a doses of 40 t ha -1 / A preocupação com a elevada quantidade de material orgânico gerado nas mais diferentes atividades humanas, é hoje em dia a sua reutilização. Assim, a utilização de lodo de esgoto tratado como adubo orgânico e condicionador físico de solos vêm sendo pesquisado para várias culturas em destaque para as espécies florestais. Desta forma este trabalho objetivou avaliar os efeitos da adição de doses de biossólidos no desenvolvimento inicial de Eucalyptus citriodora Hook. Utilizou-se para o experimento as seguintes doses de biossólido: 0, 10, 20, 30 e 40 t ha -1 com incorporação destas à camada superficial de 20 cm. Os parâmetros avaliados foram: comprimento das plantas, número de folhas, diâmetro do coleto, área foliar e biomassa seca radicular e aérea aos 60, 120, 180, 240 e 300 dias após o transplante. A análise dos resultados indicou que a viabilidade de uso está entre as doses 30 e 40 t ha -1, pois seus efeitos estão demonstrados positivamente nos parâmetros: comprimento de planta (média dos incrementos entre 30 e 40 t ha-1 igual a 38,85 cm) e número de folhas (média dos incrementos entre 30 e 40 t ha-1 de 43,9 folhas, maior que os demais tratamentos que obtiveram média igual a 35,62 folhas), assim como em diâmetro de coleto e biomassa seca aérea. Evidências na redução do acúmulo de biomassa seca radicular com a aplicação de doses crescentes do biossólido a dose 10 t ha-1 destacou-se, pois esta obteve a maior média (99,12g) do que os demais tratamentos (31,48g), indicando uma prioridade na estratégia de crescimento da espécie de rápido desenvolvimento, cujo interesse comercial destaca-se pela produção de madeira e folhas, implica na recomendação da dose de 30 t ha -1 que pode reduzir gastos em transporte e em aplicação comparativamente à dose de 40 t ha -1.
83

Modificação do resíduo de bauxita gerado no processo Bayer por tratamento térmico. / Modification of bauxite waste generated in the Bayer process by thermal treatment.

Garcia, Marta Cristina Suarez 11 May 2012 (has links)
A lama vermelha é o resíduo gerado pela Indústria do Alumínio. Assim como outros resíduos industriais apresenta características complexas com inúmeras dificuldades de manipulação, além de ser um material perigoso pela sua baixa granulometria e alcalinidade. É um resíduo com potencial poluidor alto, agravado pela forma de disposição vulnerável geralmente adotada, sendo esta a disposição do resíduo em lagoas projetadas para esta finalidade. O estudo e desenvolvimento de alternativas sustentáveis para a utilização da lama vermelha devidamente tratada como matérias-primas de outros processos são tendências importantes e necessárias no contexto mundial de preservação do meio ambiente. O objetivo deste estudo é compreender o comportamento da lama vermelha sob a influência de diferentes temperaturas de tratamento térmico. Baseados nos efeitos de redução de área e transformações de fases, característicos dos processos térmicos, adotou-se um foco de análise voltado para a redução pH e dos íons livres. A identificação dos pHs adequados de análise da concentração de íons solúveis foi feita com base nas curvas de mobilidade eletroforética e condutividade. Os resultados obtidos para as amostras calcinadas mostraram queda do pH inicial das dispersões e da concentração dos íons solubilizados. Esse efeito pode ser atribuído a redução de área e a incorporação de íons à estrutura, o que assegura ao resíduo menor reatividade. / Red mud is the waste generated by Aluminium Industry, like other industrial wastes, has complex features with several difficulties in handling, as well as being a hazardous material because of its low particle size, alkalinity and high amount generated. It is a waste with high pollution potential, compounded by the vulnerability of the disposition generally adopted, usually in lagoons designed for this purpose. The study and development of sustainable alternatives for the use of properly treated red mud, as raw material of other processes, are important tendencies and necessaries in the global context of environmental preservation. However, this work deals the thermal treatment as method to modify the characteristics of the waste, suggesting the reduction of alkalinity with the lower leaching of alkaline ions. This approach can be a discarding alternative most reliable and safe for the environment. The objective of this study is understand the red muds behavior using thermal treatment. Based on the reduction effects of the area and phase transformations characteristic of thermal process, the analysis was taken observing the reduction of free ions and pH. Identification of correct pH of analyse of soluble ions concentration was based at mobility electrophoretic and conductivity graphics. The results of calcined samples showed reduction of initial pH and the concentration of soluble ions. This effect could be assigned to the area reduction and ions incorporation at structure, which ensures the residue lower reactivity.
84

Field application of environmental DNA techniques to detect early stages of invasion by the destructive New Zealand mud snail

Woodell, James D. 01 May 2019 (has links)
Nonnative species that cause damage to ecosystems to which they are introduced are considered in-vasive. Restoration of the original ecosystem after an invasive population has established is expensive and difficult but more likely to succeed when invasions are discovered early. Containment efforts to prevent the spread of known invasions also benefit from earlier knowledge of invaded sites. Environ-mental DNA (eDNA) techniques are emerging as a tool that can identify invasive species at a distinctly earlier time point than traditional methods of detection. I collected water samples from eight sites not known to be invaded by the freshwater New Zealand mud snail (NZMS). After filtering these samples to collect eDNA, I used a species-specific probe with qPCR to identify NZMS eDNA. I found evidence for NZMS invasion at five of the eight sites, with later physical confirmation of mud snails at one of these sites. This study is the first example of successful application of eDNA to detect new invasions of the freshwater New Zealand mud snail, setting the stage for further monitoring of at-risk sites to de-tect and control new invasions of this destructive snail.
85

The Use of WBM to Improve ROP in HTHP/Hard Rock Environments

Kraussman, Andrew 2011 May 1900 (has links)
Modern day oil & gas well costs are driven by drilling performance as time becomes the dominant capital expense source. The ability to lower drilling costs becomes paramount when tight economic margins and high uncertainties/risk exist. Penetration rate decreases drastically in ultra deep formations, and substantial time is spent drilling the deepest section of these wells. Therefore, significant cost savings may be obtained through an improvement in penetration rate in deep formations. This paper shows that in HTHP (High Temperature High Pressure) hard shale/sand environments that PDC (Polycrystalline Diamond Compact) bits paired with water based mud experience 88% improvement in penetration rate than those paired with oil based mud. With this improvement in drilling rate, well costs can be substantially reduced making future ultra-deep hydrocarbon accumulations economically producible. Also observed was a drastic decrease in penetration rate in PDC bits with oil base mud which led to the use of diamond impreg bits, as the water base with PDC still maintained respectable penetration rates. The conventional penetration rate controls are still applicable in this case, but there exists a fundamental difference between the rock/fluid interactions of each mud type. Bit type, operating conditions, formation characteristics, and bit hydraulics are shown to not be the dominant influencing factor of this performance trend. The water base fluids examined have higher filtrate rates than the oil base fluids. However, a consistent data set of increasing filtrate rate corresponding to increasing penetration rate cannot be derived. Therefore filtration characteristics remain as a possible and partial influencing factor behind this data. Future experimental research is needed to confirm or disprove this theory. At this time the actual cause of this behavior is unknown, however the trend has been established showing water base drilling fluids performance versus oil base in the HTHP/hard rock environment.
86

Turbo Receiver for Spread Spectrum Systems Employing Parity Bit Selected Spreading Sequences

Mirzaee, Alireza 25 January 2012 (has links)
In spread spectrum systems employing parity bit selected spreading sequences, parity bits generated from a linear block encoder are used to select a spreading code from a set of mutually orthogonal spreading sequences. In this thesis, turbo receivers for SS-PB systems are proposed and investigated. In the transmitter, data bits are rst convolutionally encoded before being fed into SS-PB modulator. In fact, the parity bit spreading code selection technique acts as an inner encoder in this system without allocating any transmit energy to the additional redundancy provided by this technique. The receiver implements a turbo processing by iteratively exchanging the soft information on coded bits between a SISO detector and a SISO decoder. In this system, detection is performed by incorporating the extrinsic information provided by the decoder in the last iteration into the received signal to calculate the likelihood of each detected bit in terms of LLR which is used as the input for a SISO decoder. In addition, SISO detectors are proposed for MC-CDMA and MIMO-CDMA systems that employ parity bit selected and permutation spreading. In the case of multiuser scenario, a turbo SISO multiuser detector is introduced for SS-PB systems for both synchronous and asynchronous channels. In such systems, MAI is estimated from the extrinsic information provided by the SISO channel decoder in the previous iteration. SISO multiuser detectors are also proposed for the case of multiple users in MC-CDMA and MIMO-CDMA systems when parity bit selected and permutation spreading are used. Simulations performed for all the proposed turbo receivers show a signi cant reduction in BER in AWGN and fading channels over multiple iterations.
87

Reduction of TRS Emissions from Lime Kilns

Aminvaziri, Bahar 15 December 2009 (has links)
The pulp and paper industry has been struggling to meet the new and stringent TRS (Total Reduced Sulphur) emission compliance standards established in recent years. However, a new approach by some regulatory bodies gives intricate operational parameters a new and important role in achieving environmental compliance. TRS compounds that cause the distinctive pulp mill odour, originate from sodium sulphide in white liquor used in the kraft pulping process. Up to 20% of TRS emissions could originate from the lime kiln and lime mud solids content is one of the operational parameters that could help reduce the TRS emissions from the lime kiln. Residual sodium sulphide in the lime mud that results in TRS gases, is dissolved in the moisture content of the mud. Although efficient lime mud washing can remove most of the residual sodium sulphide, the remaining moisture content of the mud still contains some sodium sulphide. Therefore, improved lime mud dewatering can be effective in reducing the TRS emissions from the lime kiln. Data presented in this study confirms that as the lime mud solids content increases, TRS emissions from the lime kiln decrease. Data analysis demonstrates a negative linear correlation at 5% significance level between TRS emissions and lime mud solids.
88

Reduction of TRS Emissions from Lime Kilns

Aminvaziri, Bahar 15 December 2009 (has links)
The pulp and paper industry has been struggling to meet the new and stringent TRS (Total Reduced Sulphur) emission compliance standards established in recent years. However, a new approach by some regulatory bodies gives intricate operational parameters a new and important role in achieving environmental compliance. TRS compounds that cause the distinctive pulp mill odour, originate from sodium sulphide in white liquor used in the kraft pulping process. Up to 20% of TRS emissions could originate from the lime kiln and lime mud solids content is one of the operational parameters that could help reduce the TRS emissions from the lime kiln. Residual sodium sulphide in the lime mud that results in TRS gases, is dissolved in the moisture content of the mud. Although efficient lime mud washing can remove most of the residual sodium sulphide, the remaining moisture content of the mud still contains some sodium sulphide. Therefore, improved lime mud dewatering can be effective in reducing the TRS emissions from the lime kiln. Data presented in this study confirms that as the lime mud solids content increases, TRS emissions from the lime kiln decrease. Data analysis demonstrates a negative linear correlation at 5% significance level between TRS emissions and lime mud solids.
89

Turbo Receiver for Spread Spectrum Systems Employing Parity Bit Selected Spreading Sequences

Mirzaee, Alireza 25 January 2012 (has links)
In spread spectrum systems employing parity bit selected spreading sequences, parity bits generated from a linear block encoder are used to select a spreading code from a set of mutually orthogonal spreading sequences. In this thesis, turbo receivers for SS-PB systems are proposed and investigated. In the transmitter, data bits are rst convolutionally encoded before being fed into SS-PB modulator. In fact, the parity bit spreading code selection technique acts as an inner encoder in this system without allocating any transmit energy to the additional redundancy provided by this technique. The receiver implements a turbo processing by iteratively exchanging the soft information on coded bits between a SISO detector and a SISO decoder. In this system, detection is performed by incorporating the extrinsic information provided by the decoder in the last iteration into the received signal to calculate the likelihood of each detected bit in terms of LLR which is used as the input for a SISO decoder. In addition, SISO detectors are proposed for MC-CDMA and MIMO-CDMA systems that employ parity bit selected and permutation spreading. In the case of multiuser scenario, a turbo SISO multiuser detector is introduced for SS-PB systems for both synchronous and asynchronous channels. In such systems, MAI is estimated from the extrinsic information provided by the SISO channel decoder in the previous iteration. SISO multiuser detectors are also proposed for the case of multiple users in MC-CDMA and MIMO-CDMA systems when parity bit selected and permutation spreading are used. Simulations performed for all the proposed turbo receivers show a signi cant reduction in BER in AWGN and fading channels over multiple iterations.
90

Identity And Communication In Cyberspace Muds: Gender And Virtual Culture

Soyseckin, Idil Safiye 01 September 2006 (has links) (PDF)
This thesis investigates if it is possible to speak about a virtual culture. If so, it seeks to answers to the following questions: Is it possible to mention a culture peculiar to cyberspace or virtual culture is just a mirror of real life culture? Where does the body position? How have been identities experienced? What does fluid and fragmented identity mean? Does it offer a space of opportunities? How has been gender formed on cyberspace? Is removal of gender barriers possible? Answers to all these questions have been explored through text-based virtual reality environments on the Internet called MUDs in which creating alternative identities is possible. A survey and interviews as well as direct and participant observations for the exploration of MUD environments have been conducted. Mostly, MUDs called, LambdaMOO and Aardwolf, and then Cab&uuml / lka Cab&uuml / lsa have become central sites of observations and interviews. The findings show that cyberspace has its rules and limitations which are not independent from the real world. Since gender is a key component indicating the society interacts, culture of cyberspace cannot stay aside. Despite possibility of gender switching, stereotypical gender performances continue to exist. However cyberspace is a new and rich communication environment in respect of facilities it offers and its future structure and form largely depend on the users.

Page generated in 0.1272 seconds