Spelling suggestions: "subject:"combust??vers"" "subject:"boombust??vers""
1 |
S?ntese e caracteriza??o de biocombust?veis obtidos a partir do arroz e seus derivadosSilva, Tatiana de Oliveira Magalh?es da 15 January 2008 (has links)
Made available in DSpace on 2015-04-14T13:58:25Z (GMT). No. of bitstreams: 1
398972.pdf: 1270520 bytes, checksum: c981dc4ef6d67b9a25e1efbb0fef41df (MD5)
Previous issue date: 2008-01-15 / Este trabalho apresenta um estudo comparativo entre sistemas catal?ticos para a rea??o de transesterifica??o dos ?leos de farelo de arroz. A transesterifica??o do ?leo do farelo de arroz refinado com metanol foi avaliada na presen?a de acido sulf?rico (H2SO4) e compostos de estanho como: cloreto de estanho (SnCl2. 2H2O), 2-etilhexanoato de estanho (Sn(C8H15O2)2), conhecido comercialmente como DBTDL. Os produtos das rea??es foram caracterizados atrav?s da analise comparativa entre os catalisadores, verificou-se uma melhor performance para o DBTDL, com rendimento de 99,9% , no tempo de 4h e rela??es molares de 480:100:5 entre ?lcool, ?leo e catalisador, respectivamente . Estes resultados demonstram a viabilidade do uso de compostos met?licos como catalisadores na obten??o de biodiesel, uma alternativa interessante a catalise acida e b?sica. Nas otimiza??es do processo, foram avaliadas alcoolizes com metanol e etanol, as razoes molares foram variadas e foram utilizados como ?leo de partida, alem dos ?leos refinados, tamb?m ?leos degomados e brutos.
|
2 |
Dispositivo pino-disco para an?lise de desgaste na presen?a de diesel e biodieselVerdi, Josu? 18 August 2011 (has links)
Made available in DSpace on 2015-04-14T13:58:45Z (GMT). No. of bitstreams: 1
436188.pdf: 5507987 bytes, checksum: bb7dbc2c844572b613d5bebdeb70d2ae (MD5)
Previous issue date: 2011-08-18 / Since the biodiesel national programs began, many research groups have been studied this fuel efficiency, such as economical aspects, environments effects and engine performance and durability. The research objective was project and build a pin-on-disk device test per ASTM G99 95a (Standard Test Method for Wear Testing with a Pin-on-Disk Apparatus) to test material wear under diesel (B5) biodiesel (B100). The project validation was realized by performing aluminum-silicon wear test under two conditions: in presence of diesel (B5) and in presence of biodiesel (B100), with fix speed of 220 rpm, pin load of 5 N and 8 N during 150,000 cycles. The test analysis desired to compare the wear of an alloy used in diesel engines under different solutions. After the wear test, the disc weight loss, the topography and the microstructure were analyzed. The qualitative preliminary result shows better lubricates of biodiesel (B100) to test conditions adopted. / Desde o surgimento dos programas nacionais para a adi??o de biodiesel no diesel, diversos grupos t?m estudado a efic?cia deste combust?vel, abordando aspectos econ?micos, de meio ambiente, desempenho e durabilidade dos motores diesel. O presente trabalho tem o objetivo de projetar, construir e testar um trib?metro para an?lise de materiais submersos em biodiesel e diesel. O equipamento de teste foi desenvolvido tendo como refer?ncia a norma ASTM G99 95a (Standard Test Method for Wear Testing with a Pin-on-Disk Apparatus). A valida??o do projeto se realizou mediante ensaios de desgaste da liga alum?niosil?cio AA305 em duas condi??es: na presen?a de diesel (B5) e na presen?a de biodiesel (B100), com rota??o fixa de 220 rpm, e for?as de 5 N e 8 N durante per?odos de 150.000 ciclos. As an?lises dos dados tiveram como finalidade fazer um comparativo do desgaste da liga em estudo, utilizada em motores diesel, em diferentes solu??es. Ap?s os ensaios foram analisadas as perdas de massa, a topografia do disco e a microestrutura. A an?lise qualitativa das amostras indicou melhor lubricidade do biodiesel (B100) para as condi??es de teste adotadas.
|
3 |
Utiliza????o de estrat??gias metagen??micas para aplica????es biotecnol??gicas no setor de biocombust??veisBergmann, Jessica Carvalho 07 October 2013 (has links)
Submitted by Kelson Anthony de Menezes (kelson@ucb.br) on 2016-11-23T12:14:00Z
No. of bitstreams: 1
JessicaCarvalhoBergmannTeseparcial2013.pdf: 124515 bytes, checksum: 0d2877a5336a887b74ef27ed08081d9a (MD5) / Made available in DSpace on 2016-11-23T12:14:00Z (GMT). No. of bitstreams: 1
JessicaCarvalhoBergmannTeseparcial2013.pdf: 124515 bytes, checksum: 0d2877a5336a887b74ef27ed08081d9a (MD5)
Previous issue date: 2013-10-07 / The necessity to be a self-suficient producer of fuels is stimulating research for alternative
types of energy. Brazil, as well as other countries, is investing in this sector and in 2012 was
the second largest biofuel producer in the world. Bioethanol production can double
productivity with second generation technology in which bioethanol is produced from
cellulose. Biodiesel production from oils using different feedstocks can also contribute for
this independency in biofuels production, both locally and globally. This doctorate thesis is
divided in two chapters, both attempting to make a contribution to the development of the
biofuels sector in Brazil. The first chapter focuses on enzyme discovery for ethanol
production from cellulose. The second chapter focuses on the characterization of the soil
microbiota associated with oil palm plants with fatal yellowing, which has hindered the
development of a biodiesel industry based on palm oil. The first chapter describes prospection
for hydrolytic enzymes to be used for biomass deconstruction in second generation bioethanol
production. Enzymes were screened from an Amazon soil large insert metagenomic library
(30-50 kb). The library containing approximately 213,000 clones was functionally screened,
and 15 clones with cellulolytic activity and 16 clones resistant to hydroquinone were
identified. The sequences of these 31 clones and an additional 65 other random clones were
obtained and analysed using the IMG/MER pipeline. In silico analysis identified several
coding regions (CDS) that were amplified by PCR and cloned in expression vectors. The
sequences for two beta-glucosidases enzymes, BGL17 and BGL18, were codon optimized
before being expressed and purified. Characterization of both enzymes showed that the
optimum temperature for BGL17 and BGL18 was 45oC and 40oC, respectively. The optimum
pH for BGL17 and BGL18 was 6.0 and for 6.5, respectively. Half-life stability was
approximately one hour for both enzymes. Regarding enzyme kinetics, BGL18 showed higher
Vmax and Km (11 U/mg ?? 0.0011 and 0.36 mM ?? 0.01612) when compared to BGL17 (85
U/mg ?? 0.0028 and 0.30 mM ?? 0.017). Kcat was only calculated for BGL17 as 38.57 s-1 ?? 0.37
as the purification of BGL18 was not successfull. Chapter two aimed to study the soil
bacterial diversity from oil palm trees affected by fatal yellowing disease (bud rot) in three
different stages. The strategy used was pyrosequencing of the gene for the 16S ribosomal
RNA (16S rRNA). Oil palm is an oilcrop produced in the north region of Brazil with hight oil
yield, which makes it a good candidate for biodiesel production. However, oil palm trees are
being affected by fatal yellowing (FY) for more than 20 years, but to this date no etiological
agent was identified. Observation was reported where healthy palm tree were planted in the
same spot as previously sick tree, developed FY after a period of time, suggesting that the
disease could be transmitted by some microorganism in the soil. In this work, the gene for
16S rRNA was amplified from DNA extracted from soil of diseased oil palm trees (stages 5
and 8) and from plants with no symptoms of the disease and sequenced. Pyrosequencing
originated 839,694 sequences. After artifacts and chimeras were removed, 498,397 sequences
distributed in 9 samples (3 for each disease stage) remained to be analyzed. Sequences were
analyzed using the Qiime pipeline (Quantitative Insights in Microbial Ecology) and
taxonomic classification of sequences was obtained based on the RDP (Ribossomal Database
Project). The most abundant phyla in the samples were Acidobacteria, Proteobacteria,
Planctomycetes, Firmicutes and Verrucomicrobia. Alpha and Beta diversity were calculated
and taxonomic comparisons were performed by STAMP software. Results showed that the
bacterial communtiy associated with soils of diseaded plants on stage 5 (DCA5) and stage 8
had a higher number of observed OTUs than stage 0, as determined by the Chao1
phylogenetic diversity index. Beta-diversity analysis showed that the different biological
replicates of soil from diseased plants of the same stage are significantly different, as shown
in PCoA (Principal Coordenate Analysis). Taxonomic comparison showed more rare phyla
associated to stages 5 and 8 of the disease. This work is the first to study the bacterial
microbiota associated with soils of oil palm plants with and without symptoms of fatal
yellowing with next generation sequencing. / A necessidade de produzir combust??veis para que futuramente haja independ??ncia na
produ????o de energia, vem impulsionando pesquisas no setor de energias alternativas. O
Brasil, assim como outros pa??ses emergentes, tem investido e ganhado espa??o neste cen??rio,
sendo hoje o segundo maior produtor mundial de biocombust??veis. A produ????o de bioetanol,
apesar de j?? bem estabelecida no pa??s, poder?? dobrar com a tecnologia de produ????o de etanol
de segunda gera????o (a partir da biomassa). Al??m disso, com a produ????o de biodiesel a partir
do ??leo de diferentes culturas oleaginosas poder?? contribuir para esta independ??ncia na
produ????o de biocombust??veis localmente e globalmente. Esta tese est?? dividida em dois
cap??tulos, ambos tratando como produto final a produ????o de biocombust??veis. O cap??tulo um
teve como objetivo a prospec????o de enzimas hidrol??ticas para serem utilizadas durante o
processo de hidr??lise enzim??tica e clones resistentes a produtos secund??rios formados durante
o processo de pr??-tratamento na produ????o de etanol de segunda gera????o. Construiu-se uma
biblioteca metagen??mica de grandes insertos (30-50 kb) em fosm??deo a partir de DNA da
comunidade microbiana do solo amaz??nico. A biblioteca contendo aproximadamente 213.000
clones foi triada funcionalmente, identificando 15 clones com atividade celulol??tica e 16
clones resistentes ?? hidroquinona (produto t??xico a leveduras produzido durante o pr??tratamento).
Estes 31 clones com atividade na triagem funcional, somados a outros 65 clones
selecionados aleatoriamente, foram sequ??nciados e suas sequ??ncias depositadas no pipeline
IMG/MER (JGI) onde foram anotadas. A an??lise computacional dos clones com atividades
enzim??ticas permitiu a identifica????o de diferentes regi??es codificantes (CDs) que foram
amplificadas por PCR e clonadas em vetores de express??o. Conseguiu-se a express??o de duas
enzimas beta-glicosidases (BGL17 e BGL18) que tiveram suas sequ??ncias otimizadas antes
de serem purificadas. A caracteriza????o destas enzimas mostrou que a BGL17 e BGL18
possuem uma temperatura ??tima de 45oC e 40oC, respectivamente, e um pH ??timo de 6 e 6,5,
respectivamente, com estabilidade m??dia nestas condi????es em torno de uma hora. A BGL17
possui um valor de Vmax e Km de 85 U/mg e 0,30 mM ?? 0.017 enquanto a BGL18 possui os
valores de Vmax e Km de 11,01 U/mg e 0,36 mM ?? 0,01612. O cap??tulo dois visou o estudo da
microbiota de solo de dendezeiros acometidos pelo amarelecimento fatal (AF) em diferentes
est??gios da doen??a utilizando como estrat??gia o pirosequenciamento do gene para 16S rRNA.
A planta do dend?? ?? uma oleaginosa produzida principalmente no norte do Brasil e possui um
alto rendimento de ??leo o que a torna uma boa candidata a produ????o de biodiesel. Por??m, o
dendezeiros t??m sido acometidos pelo AF, sendo seu agente etiol??gico procurado h?? mais de
20 anos sem resultados conclusivos. Plantas sadias que foram replantadas no mesmo lugar de
plantas doentes desenvolveram a doen??a, criando-se a hip??tese da transmiss??o do AF ocorrer
pelo solo. Neste trabalho, realizou-se o pirosequenciamento do gene para 16S rRNA
amplificado da comunidade bacteriana de uma amostra de solo da base de dendezeiros
acometidos por AF em dois est??gios da doen??a (est??gio 5 e est??gio 8) e aparentemente sem
doen??a (est??gio 0). O sequenciamento gerou 839.694 sequ??ncias que depois de retirados os
artefatos totalizaram 498.397 sequ??ncias distribu??das em 9 pontos (3 para cada est??gio da
doen??a). As sequ??ncias foram analisadas utilizando-se o programa Qiime (Quantitative
Insights in Microbial Ecology) e sua classifica????o taxon??mica atribu??da de acordo com o
RDP-II (Ribossomal Database Project). Os filos mais abundantes encontrados foram
Acidobacteria, Proteobacteria, Planctomycetes, Firmicutes e Verrucomicrobia. An??lises de
alfa e beta diversidade foram realizadas e compara????es taxon??micas foram feitas utilizando o
programa STAMP (Statistical Analysis of Metagenomic Profiles). Os resultados mostraram
que os pontos DCA5 (dendezeiros com AF no est??gio 5 da doen??a) apresentam maior
quantidade de OTUs observadas em rela????o a diversidade filogen??tica e ??ndice de Chao1. As
an??lises de beta-diversidade mostraram que os agrupamentos entre os pontos por sintomas da
doen??a s??o significativamente diferentes. Compara????es taxon??micas mostraram uma maior
presen??a de filos raros nos est??gios 5 e 8. Este trabalho foi o primeiro realizado tentando
elucidar o causador do AF utilizando sequenciamento de ??ltima gera????o. Estes resultados ir??o
contribuir para futuros estudos do Amarelecimento Fatal.
|
4 |
Estudo comparativo de diferentes sistemas de inje??o de vapor aplicados ? remedia??o de solos contaminados por dieselBezerril, Rayana Hozana 25 July 2014 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2015-12-04T20:21:19Z
No. of bitstreams: 1
RayanaHozanaBezerril_TESE.pdf: 1462425 bytes, checksum: cac67c7bf1570bf9fe04615be96e17d0 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2015-12-09T23:46:58Z (GMT) No. of bitstreams: 1
RayanaHozanaBezerril_TESE.pdf: 1462425 bytes, checksum: cac67c7bf1570bf9fe04615be96e17d0 (MD5) / Made available in DSpace on 2015-12-09T23:46:58Z (GMT). No. of bitstreams: 1
RayanaHozanaBezerril_TESE.pdf: 1462425 bytes, checksum: cac67c7bf1570bf9fe04615be96e17d0 (MD5)
Previous issue date: 2014-07-25 / Dentre as atividades econ?micas potencialmente poluidoras que comprometem a qualidade do solo e da ?gua subterr?nea est?o os postos revendedores de combust?veis. O vazamento de combust?veis derivados do petr?leo a partir de tanques subterr?neos ou atividades realizadas indevidamente com estes poluentes podem contaminar extensas ?reas, causando s?rios problemas ambientais e toxicol?gicos. O n?mero de postos de combust?veis cresceu desordenadamente, sem nenhum tipo de controle, com isso os impactos ambientais gerados por esses empreendimentos cresceram ocasionando a polui??o do solo e da ?gua subterr?nea. V?rias t?cnicas utilizando tensoativos t?m sido propostas para remedia??o deste tipo de contamina??o. Este estudo apresenta como inova??o a aplica??o de diferentes sistemas contendo tensoativos na fase vapor e compara suas efici?ncias de remo??o de diesel de um solo contendo esse contaminante. Para isso, foi utilizado um sistema que cont?m sete po?os injetores das seguintes solu??es vaporizadas : ?gua, solu??es de tensoativo, microemuls?o e nanoemuls?o, Os tensoativos utilizados foram o ?leo de Coco Saponificado (OCS), em solu??o aquosa e um ?lcool etoxilado UNTL-90: em solu??o aquosa, e em sistemas de microemuls?o e nanoemuls?o. Dentre os sistemas investigados, a nanoemuls?o foi a que apresentou maior efici?ncia de remo??o com 88% do diesel, sendo a mais vi?vel ecol?gica e tecnicamente por ser um sistema com menor teor de mat?ria ativa. / Among the potentially polluting economic activities that compromise the quality of soil and
groundwater stations are fuel dealers. Leakage of oil derived fuels in underground tanks or
activities improperly with these pollutants can contaminate large areas, causing serious
environmental and toxicological problems. The number of gas stations grew haphazardly,
without any kind of control, thus the environmental impacts generated by these enterprises
grew causing pollution of soil and groundwater. Surfactants using various techniques have
been proposed to remedy this kind of contamination. This study presents innovation as the
application of different systems containing surfactant in the vapor phase and compares their
diesel removal efficiencies of soil containing this contaminant. For this, a system that contains
seven injection wells the following vaporized solutions: water, surfactant solution,
microemulsion and nanoemulsion, The surfactants used were saponified coconut oil (OCS), in
aqueous solution and an ethoxylated alcohol UNTL-90: aqueous solution , and nanoemulsion
and microemulsion systems. Among the systems investigated, the nanoemulsion showed the
highest efficiency, achieving 88% removal of residual phase diesel, the most ecologically and
technically feasible by a system with lower content of active matter
|
5 |
Estudo do potencial poluidor da atividade de revenda de combust?veis l?quidos na cidade de Natal (RN): justificativas para a implanta??o da rotulagem ambiental (Selo Verde)Torres Neto, Jos? Correia 16 March 2012 (has links)
Made available in DSpace on 2014-12-17T14:58:13Z (GMT). No. of bitstreams: 1
JoseCTN_DISSERT.pdf: 3330335 bytes, checksum: 998a47f5aaa9275ec35cf7e52cf1d08e (MD5)
Previous issue date: 2012-03-16 / This work presents the analysis of data collected by Universidade Federal do Rio Grande do Norte and State Public Prosecution Office experts concerning to current situation of liquid fuel resale stations, its forms of storage and its technical apparatus for the performance of primary functions (supply of vehicles) and secondary (car washing, storage of used oil, oil change etc.). The data presented were analyzed in the setting of the city of Natal (RN) and considering its characteristics, potentialities and weaknesses. Thereafter, it was discussed liquid fuels resale pollution potential in the city and legal provisions directed to implementation of Green Seal. The discussion involves three agents: environmental, legal and technical ones, applied to all 110 resale fuel stations which were analyzed / Este trabalho apresenta a an?lise dos dados colhidos pelos peritos da Universidade Federal do Rio Grande do Norte e do Minist?rio P?blico Estadual referentes ? situa??o dos postos de revenda de combust?veis l?quidos, suas formas de armazenamento e o seu aparato t?cnico para o exerc?cio das fun??es principal (abastecimento de ve?culos) e secund?ria (lavagem de ve?culos, armazenamento de ?leo usado, troca de ?leo etc.). Os dados apresentados foram analisados sob a configura??o da Cidade de Natal (RN) e levando-se em considera??o suas caracter?sticas, potencialidades e fragilidades. Da? por diante, discutiu-se sobre o potencial poluidor da atividade de revenda de combust?veis l?quidos na cidade e as disposi??es legais direcionadas para a implanta??o do Selo Verde. A discuss?o apresentada envolve principalmente tr?s agentes: o ambiental, o legal e o t?cnico, aplicados aos 110 postos de revenda de combust?veis analisados
|
6 |
Taxa de evapora??o de combust?veis em fun??o da temperatura: an?lise termoecon?mica aplicada a postos de servi?os do RN / Fuel evaporation temperature: analysis economic term applied to gas stations of the RNAndr?, Thiago da Silva 19 December 2016 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-03-20T20:04:27Z
No. of bitstreams: 1
ThiagoDaSilvaAndre_DISSERT.pdf: 3053224 bytes, checksum: bd505205f3c547b71bf4aef350ec5642 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-03-22T21:27:33Z (GMT) No. of bitstreams: 1
ThiagoDaSilvaAndre_DISSERT.pdf: 3053224 bytes, checksum: bd505205f3c547b71bf4aef350ec5642 (MD5) / Made available in DSpace on 2017-03-22T21:27:33Z (GMT). No. of bitstreams: 1
ThiagoDaSilvaAndre_DISSERT.pdf: 3053224 bytes, checksum: bd505205f3c547b71bf4aef350ec5642 (MD5)
Previous issue date: 2016-12-19 / Este trabalho ? resultado de um estudo de an?lises experimentais que mediram a taxa de evapora??o, em fun??o da temperatura, de quatro combust?veis, a saber: gasolina comum, ?lcool combust?vel, Diesel S10 e gasolina GRID, realizados para seis n?veis t?rmicos diferentes, seguido de uma an?lise de custos das perdas potenciais por evapora??o, aplicada a tanques subterr?neos de postos de combust?veis. Quando esses combust?veis liberam vapores ? atmosfera podem causar danos ao meio ambiente. Em postos de servi?os, esse vapor ? liberado quando do abastecimento do ve?culo ou pelas linhas de respiro do Sistema de Abastecimento Subterr?neo de Combust?veis - SASC. Quando o posto n?o possui prote??es contra essas emiss?es fugitivas, elas atingem flora, rios, len??is fre?ticos etc. Al?m da polui??o dos recursos naturais, a perda por evapora??o atinge as finan?as do posto de combust?vel, tanto pelas multas geradas pelas contamina??es, quanto pela perda de ativo, os combust?veis. Dos combust?veis avaliados, o que apresentou a maior taxa de evapora??o foi a gasolina GRID, seguido da gasolina comum, ?lcool e diesel S10. / This work is the result of a study of experimental tests that measured the rate of evaporation, temperature, of four fuels, namely: ordinary gasoline, ethanol fuel, Diesel and gas GRID, S10 for six different heat levels, followed by a cost analysis of the potential losses for evaporation, applied to underground tanks of gas stations. When these fuels release vapors into the atmosphere can cause damage to the environment. In service stations, this vapor is released when the supply of the vehicle or the vent lines of Underground fuel supply system-SASC. When the gas station does not have protections against these fugitive emissions, they reach flora, rivers, groundwater etc. Apart from the problem of pollution of natural resources, the loss by evaporation reaches the finances of the gas station, both by the fines generated by the contamination, and the loss of active, fuel. Of fuels evaluated presented the highest evaporation rate was the gas GRID, followed by ordinary gasoline, alcohol and diesel S10.
|
7 |
Influ?ncia do uso de combust?veis alternativos na s?ntese por combust?o via microondas para a produ??o de materiais cer?micos com estrutura espin?lioSilva, Walquiria Joseane da 21 July 2011 (has links)
Made available in DSpace on 2014-12-17T14:06:58Z (GMT). No. of bitstreams: 1
WalquiriaJS_DISSERT_PACIAL.pdf: 740304 bytes, checksum: 3d1d601a3873230ed2af2ce67496fdf5 (MD5)
Previous issue date: 2011-07-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The development and study of detectors sensitive to flammable combustible and toxic gases at
low cost is a crucial technology challenge to enable marketable versions to the market in
general. Solid state sensors are attractive for commercial purposes by the strength and
lifetime, because it isn t consumed in the reaction with the gas. In parallel, the use of
synthesis techniques more viable for the applicability on an industrial scale are more attractive
to produce commercial products. In this context ceramics with spinel structure were obtained
by microwave-assisted combustion for application to flammable fuel gas detectors.
Additionally, alternatives organic-reducers were employed to study the influence of those in
the synthesis process and the differences in performance and properties of the powders
obtained. The organic- reducers were characterized by Thermogravimetry (TG) and
Derivative Thermogravimetry (DTG). After synthesis, the samples were heat treated and
characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD),
analysis by specific area by BET Method and Scanning Electron Microscopy (SEM).
Quantification of phases and structural parameters were carried through Rietveld method. The
methodology was effective to obtain Ni-Mn mixed oxides. The fuels influenced in obtaining
spinel phase and morphology of the samples, however samples calcined at 950 ?C there is just
the spinel phase in the material regardless of the organic-reducer. Therefore, differences in
performance are expected in technological applications when sample equal in phase but with
different morphologies are tested / O desenvolvimento e estudo de detectores sens?veis a gases combust?veis inflam?veis e
t?xicos de baixo custo ? um desafio tecnol?gico determinante para possibilitar vers?es
comercializ?veis ao mercado em geral. Sensores no estado s?lido s?o atrativos para fins
comerciais pela robustez e tempo de vida, uma vez que n?o s?o consumidos durante o
processo de rea??o com o g?s. Paralelamente, o uso de t?cnicas de s?ntese mais vi?veis pela
aplicabilidade em escala industrial s?o mais atrativas para obten??o de produtos comerciais.
Dentro desse contexto foram obtidos materiais cer?micos com estrutura espin?lio via
combust?o assistida por microondas, visando aplica??o em detectores de gases combust?veis
inflam?veis. Adicionalmente foram empregados direcionadores-org?nicos alternativos para
estudo da influ?ncia dos mesmos no processo de s?ntese e nas diferen?as nas propriedades e
desempenho dos p?s obtidos. Os direcionadores-org?nicos foram caracterizados por
Termogravimetria (TG). Ap?s a s?ntese, as amostras foram tratadas termicamente e
caracterizadas por Espectroscopia de absor??o na regi?o do infravermelho com Transformada
de Fourier (FTIR), Difra??o de Raios X (DRX), Medidas de ?rea espec?fica por BET e
Microscopia Eletr?nica de Varredura (MEV). A quantifica??o de fases e a determina??o de
par?metros estruturais foram determinados por refinamento atrav?s do M?todo Rietveld. A
metodologia empregada foi eficaz para obten??o de ?xidos mistos Ni-Mn. Os combust?veis
utilizados influenciaram na obten??o da fase espin?lio e na morfologia das amostras, sendo
que as amostras calcinadas a 950?C s?o monof?sicas independentemente do direcionador.
Logo, diferen?as de desempenho s?o esperadas em aplica??es tecnol?gicas quando amostras
iguais em fase mas com diferentes morfologias s?o testadas
|
8 |
Fatores que influenciam a fidelidade dos clientes em postos de combust?veis da cidade de Natal/RNMello, Luciana Torres Correia de 06 December 2013 (has links)
Made available in DSpace on 2014-12-17T14:53:18Z (GMT). No. of bitstreams: 1
LucianaTCM_DISSERT.pdf: 2651795 bytes, checksum: 7c2c35dffa683db2b43fb59f0a6f1b0e (MD5)
Previous issue date: 2013-12-06 / The customer loyalty became strategy factor for the sustainability of business enterprises. And will be them competitive is important to describe the factors than the consumers consider for to choose the business than will buy the product or service. The dissertation objective is to know the factors that influence the consumer s satisfaction and loyalty in gas stations of Natal/RN, using the index national of customer satisfaction. The literature review was directed for strategy concepts, service quality, satisfaction and fidelity consumer and index national of customer satisfaction. The method used was descriptive-explicative, with application of a survey, from march 15 until april 15 of 2013, with 391 consumers of gas station. In relational analysis, we considered eight constructs: quality, price, complaints, satisfaction, image, loyalty, affection and commitment calculated. For customer satisfaction, the factors that influence have resulted in fuel quality, technical skills of vendors and duration of service. For customer loyalty, the factors that influence resulted in: image, feeling for distributor flag post, location and overall satisfaction with the gas station / A fidelidade dos clientes tornou-se fator estrat?gico para a sustentabilidade do neg?cio das empresas. E para torn?-las competitivas ? importante identificar os fatores que os clientes levam em considera??o para escolher a empresa em que ir?o comprar o produto/servi?o. Esta disserta??o de mestrado objetiva conhecer os fatores que influenciam a satisfa??o e fidelidade dos clientes em postos de combust?veis de Natal/RN, tomando como base o modelo noruegu?s de ?ndice de satisfa??o do consumidor. A pesquisa te?rica foi fundamentada nos conceitos de estrat?gia, qualidade nos servi?os, satisfa??o e fidelidade do cliente e especificamente nos ?ndices nacionais de satisfa??o do cliente. O m?todo utilizado foi descritivo-explicativo, com aplica??o de uma pesquisa do tipo survey, no per?odo de 15 de mar?o ? 15 de abril de 2013, com 391 clientes de postos de combust?veis. Foram considerados na an?lise relacional oito constructos: qualidade, pre?o, reclama??o, satisfa??o, imagem, fidelidade, afetividade e compromisso calculado. Para a satisfa??o dos clientes, os fatores que influenciam resultaram em: qualidade do combust?vel; habilidades t?cnicas dos vendedores e tempo de atendimento. Para a fidelidade do cliente, os fatores que influenciaram resultaram em: imagem, sentimento em rela??o a bandeira distribuidora, localiza??o do posto e satisfa??o geral com o posto
|
9 |
Prepara??o de ?xidos mistos de n?quel e zinco nanoparticulados a partir de combust?veis alternativosSilva, Rayssa Rafaelli Nunes Melo da 31 August 2012 (has links)
Made available in DSpace on 2014-12-17T14:07:06Z (GMT). No. of bitstreams: 1
RayssaRNMS_DISSERT.pdf: 4171010 bytes, checksum: 0d447597643468751a7d9a8d1824c61d (MD5)
Previous issue date: 2012-08-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The field of "Materials Chemistry" has been developing in recent years and there has
been a great increase of interest in the synthesis and chemical and physical properties of
new inorganic solids. New routes of synthesis and synthesis modified has been
developed with the aim not only to optimize the processes in laboratory scale, but also
on an industrial scale, and make them acceptable by current environmental legislation.
The phenomenology of current solid state chemistry properties coupled with the high
temperature superconductivity, ferromagnetism, porosity molecular and colors are
evidence affected by the synthesis method, which in turn can influence the
technological application of these materials. From this understanding, mixed oxides of
nickel and zinc nanoparticulate were synthesized by microwave-assisted combustion
route using three specific types of organic fuels employing the weight ratios 1:1/2 and
1:1 of cation metallic/fuel, in order to investigate the influence of such proportions to
obtain the solids. The new fuels were chosen to replace, for example, urea or glycine
that are the fuels most commonly preferred in this kind of synthesis. The powders
without heat treatment were studied by Thermogravimetric analysis (TGA), X-Ray
Diffraction (XRD) and then calcined at 900?C. After heat treatment, the samples were
characterized by analysis of X Ray Diffraction (XRD) and Scanning Electron
Microscopy (SEM). The modified synthesis route porposed was effective for obtaining
powders. Both the alternative fuels chosen as the different weight ratios employed,
influenced in the morphology and obtaining oxides / O campo da Qu?mica de Materiais vem se desenvolvendo nos ?ltimos anos, tendo
havido um grande aumento do interesse na s?ntese e nas propriedades qu?micas e f?sicas
de novos s?lidos inorg?nicos. Novas rotas de s?nteses e s?nteses modificadas tem sido
desenvolvidas com o intuito n?o apenas de otimizar os processos em escala
laboratorial, como tamb?m em escala industrial, al?m de torn?-los aceit?veis pela
legisla??o ambiental vigente. A atual fenomelogia da qu?mica do estado s?lido aliada ?s
propriedades de supercondutividade ? alta temperatura, ferromagnetismo, porosidade
molecular e cores s?o evid?ncias afetadas pelo m?todo de s?ntese, que por sua vez,
podem influenciar na aplica??o tecnol?gica desses materiais. Foi a partir desta
compreens?o, que ?xidos mistos de n?quel e zinco nanoparticulados foram sintetizados
atrav?s da rota combust?o por microondas utilizando tr?s tipos espec?ficos de
combust?veis e empregando as raz?es m?ssicas 1:1 e 1:1/2 de c?tions
met?licos/combust?vel, com o intuito de averiguar a influ?ncia de tais propor??es na
obten??o dos s?lidos. Os novos combust?veis foram escolhidos em substitui??o a ur?ia
ou glicina que s?o mais comumente preferidos nesse tipo de s?ntese. Os p?s sem
tratamento t?rmico foram estudados atrav?s da An?lise Termogravim?trica (ATG) e da
Difra??o de Raios-X (DRX), sendo, em seguida, submetidos ao tratamento t?rmico ?
900?C. Ap?s as calcina??es, foram caracterizados atrav?s das an?lises Difra??o de raiosx
(DRX) e Microscopia Eletr?nica de Varredura (MEV). A rota de s?ntese modificada
foi eficaz para obten??o dos p?s. Tanto os combust?veis alternativos escolhidos quanto
as diferentes raz?es m?ssicas empregadas, influenciaram na morfologia e na obten??o
dos ?xidos
|
10 |
Avalia??o de HPA e BTEX no solo e ?gua subterr?nea, em postos de revenda de combust?veis: estudo de caso na cidade de Natal -RNAnjos, Raoni Batista dos 14 December 2012 (has links)
Made available in DSpace on 2014-12-17T14:08:52Z (GMT). No. of bitstreams: 1
RaoniBA_DISSERT.pdf: 2283831 bytes, checksum: 9e3bfc1213fc5b5ac439fb175ddc5631 (MD5)
Previous issue date: 2012-12-14 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The retail fuel stations are partially or potentially polluters and generators of
environmental accidents, potentially causing contamination of underground and
surface water bodies, soil and air. Leaks in fuel retail stations? underground storage
systems are often detected in Brazil and around the world. Monoaromatic
hydrocarbons, BTEX (benzene, toluene, ethylbenzene and xylenes) and polycyclic
aromatic hydrocarbons (PAHs) are an indication of the presence of contamination due
to its high toxicity. This paper presents a case study of contamination in a Fuel Retail
Station by petroleum derivative products in the city of Natal. For identification and
quantification of the hydrocarbons, EPA analytical methods were used. The values of
benzene quantified by EPA method 8021b CG-PID/FID, ranged from 1.164 to 4.503
mg.Kg-1 in soil samples, and from 12.10 to 27,639 μg.L-1 in underground water
samples. Among the PAHs, naphthalene and anthracene showed the most significant
results in soil samples, 0.420 to 15.46 mg.Kg-1 and 0.110 to 0,970 mg.Kg-1,
respectively. In underground water samples, the results for Naphthalene varied
between 0.759 and 614.7 μg.L-1. PAHs were quantified by EPA Method 8270 for GCMS.
All of the results for the chemical analysis were compared with the values for the
CONAMA 420/2009 resolution. The results for benzene (27,639 μg.L-1) showed levels
highly above the recommended by the CONAMA 420 resolution, wherein the
maximum permissible for underground water is 5 μg.L-1. This is a worrying factor,
since underground water makes up 70% of the city of Natal?s water supply / The retail fuel stations are partially or potentially polluters and generators of
environmental accidents, potentially causing contamination of underground and
surface water bodies, soil and air. Leaks in fuel retail stations? underground storage
systems are often detected in Brazil and around the world. Monoaromatic
hydrocarbons, BTEX (benzene, toluene, ethylbenzene and xylenes) and polycyclic
aromatic hydrocarbons (PAHs) are an indication of the presence of contamination due
to its high toxicity. This paper presents a case study of contamination in a Fuel Retail
Station by petroleum derivative products in the city of Natal. For identification and
quantification of the hydrocarbons, EPA analytical methods were used. The values of
benzene quantified by EPA method 8021b CG-PID/FID, ranged from 1.164 to 4.503
mg.Kg-1 in soil samples, and from 12.10 to 27,639 μg.L-1 in underground water
samples. Among the PAHs, naphthalene and anthracene showed the most significant
results in soil samples, 0.420 to 15.46 mg.Kg-1 and 0.110 to 0,970 mg.Kg-1,
respectively. In underground water samples, the results for Naphthalene varied
between 0.759 and 614.7 μg.L-1. PAHs were quantified by EPA Method 8270 for GCMS.
All of the results for the chemical analysis were compared with the values for the
CONAMA 420/2009 resolution. The results for benzene (27,639 μg.L-1) showed levels
highly above the recommended by the CONAMA 420 resolution, wherein the
maximum permissible for underground water is 5 μg.L-1. This is a worrying factor,
since underground water makes up 70% of the city of Natal?s water supply
|
Page generated in 0.0593 seconds