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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.
21

Mathematical Modeling Of Fluidized Bed Combustors With Radiation Model

Alagoz, Duriye Ece 01 August 2006 (has links) (PDF)
Simultaneous solution of the conservation equations for energy and chemical species in conjunction with radiative transfer equation was carried out by coupling a previously developed and tested system model of fluidized bed combustion (FBC) to an existing radiation model. The predictive accuracy of the coupled code was assessed by applying it to 0.3 MWt METU Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) Test Rig burning lignite in its own ash and comparing its predictions with the measured temperatures and concentrations of gaseous species along the combustor and radiative heat fluxes incident on the refractory-lined freeboard walls on two combustion tests, with and without recycle. The predictions of the coupled code were found to be in good agreement with the measurements. For the investigation of the significance of coupling of the radiation model to the system model, temperature predictions of the coupled code were compared with those obtained by the original system model. It was found that the effect of incorporating a radiation model into the system model on the predictions was not significant because the high temperatures of refractory-lined freeboard walls and high surface to volume ratio of the test rig under consideration cause the incident radiative heat fluxes to be dominated by walls rather than the particle laden gas emissions. However, in industrial boilers, freeboard is surrounded by water-cooled membrane walls and boilers have much lower surface to volume ratio. In order to examine the effects of both on radiation in industrial boilers, an investigation was carried out on 16 MWt Stationary Fluidized Bed Boiler (SFBB) by applying radiation model, in isolation from the system model, to the freeboard of the boiler. It was found that in the boiler, incident radiative heat fluxes were dominated by particle laden gas emissions. In brief, the coupled code proposed in this study proves to be a useful tool in qualitatively and quantitatively simulating the processes taking place in an atmospheric fluidized bed boilers.
22

Conduc?o eletr?nica e propriedades termodin?micas da mol?cula de DNA

Sarmento, Ricardo Gondim 28 May 2012 (has links)
Made available in DSpace on 2015-03-03T15:16:26Z (GMT). No. of bitstreams: 1 RicardoGS_TESE.pdf: 1607151 bytes, checksum: 892ba8afc1733edc8e855073b58ee05c (MD5) Previous issue date: 2012-05-28 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In this thesis, we study the thermo-electronic properties of the DNA molecule. For this purpose, we used three types of models with the DNA, all assuming a at geometry (2D), each built by a sequence of quasiperiodic (Fibonacci and / or Rudin-Shapiro) and a sequence of natural DNA, part of the human chromosome Ch22. The first two models have two types of components that are the nitrogenous bases (guanine G, cytosine C, adenine A and thymine T) and a cluster sugar-phosphate (SP), while the third has only the nitrogenous bases. In the first model we calculate the density of states using the formalism of Dyson and transmittance for the time independent Schr odinger equation . In the second model we used the renormalizationprocedure for the profile of the transmittance and consequently the I (current) versus V (voltage). In the third model we calculate the density of states formalism by Dean and used the results together with the Fermi-Dirac statistics for the chemical potential and the quantum specific heat. Finally, we compare the physical properties found for the quasi-periodic sequences and those that use a portion of the genomic DNA sequence (Ch22). / Nesta tese, estudamos as propriedades termo-eletr?nicas da mol?cula de DNA. Para tal prop?sito, fizemos uso de tr?s tipos de modelos com o DNA, todos assumindo uma geometria plana (2D), constru?dos cada um atrav?s das sequ?ncias quase-peri?dicas (Fibonacci e/ou Rudin-Shapiro) e de uma sequ?ncia de DNA natural, parte do cromossomo humano Ch22 . Os dois primeiros modelos apresentam dois tipos de componentes que s?o: as bases nitrogenadas (Guanina G, citosina C, Adenina A e Timina T) e um grupamento a??car-fosfato (SP), enquanto o terceiro modelo apresenta somente as bases nitrogenadas. No primeiro modelo calculamos as densidades de estados utilizando o formalismo de Dyson e as transmit?ncias pela equac?o de Schr?dinger independente do tempo. No segundo modelo fizemos uso do processo de renormalizac?o para obtemos os perfis das transmit?ncias e consequentemente as curvas I (corrente) _ V (voltagem). No terceiro modelo calculamos as densidades de estados pelo formalismo de Dean e utilizamos os resultados juntamente com a estat?stica de Fermi-Dirac para obtemos os potenciais qu?micos e os calores espec?ficos qu?nticos. Finalmente, comparamos as propriedades f?sicas encontradas para as sequ?ncias quase-peri?dicas e para aqueles que utilizam um trecho da sequ?ncia gen?mica do DNA (Ch22)
23

Desenvolvimento de m?todo para determina??o de cloro em petr?leo via mol?cula MgCl por HR-CS MAS

Oliveira, Izabel Kaline da Silva 28 July 2017 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-01-24T12:15:33Z No. of bitstreams: 1 IzabelKalineDaSilvaOliveira_TESE.pdf: 1323354 bytes, checksum: 0c2134eae1c9170e6277290fc8a4b9da (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-01-26T13:30:04Z (GMT) No. of bitstreams: 1 IzabelKalineDaSilvaOliveira_TESE.pdf: 1323354 bytes, checksum: 0c2134eae1c9170e6277290fc8a4b9da (MD5) / Made available in DSpace on 2018-01-26T13:30:04Z (GMT). No. of bitstreams: 1 IzabelKalineDaSilvaOliveira_TESE.pdf: 1323354 bytes, checksum: 0c2134eae1c9170e6277290fc8a4b9da (MD5) Previous issue date: 2017-07-28 / Ag?ncia Nacional de Petr?leo - ANP / O cloreto ? considerado um dos principais contaminantes do petr?leo, pois interfere no processo de transporte e refino e pode ser transferido para os produtos derivados finais. Durante o refino, a presen?a de cloreto pode levar a forma??o de HCl, causando s?rios problemas de corros?o. Nesse sentido, foi desenvolvida uma metodologia para determina??o de cloro em amostras de petr?leo, preparadas sob a forma de emuls?es, por espectrometria de absor??o molecular de alta resolu??o com fonte cont?nua atrav?s da mol?cula diat?mica MgCl no comprimento de onda 377,01 nm. O preparo da emuls?o foi otimizado atrav?s de um planejamento experimental Centroid-Simplex. As condi??es ?timas de preparo das emuls?es foram: 0,5mL HNO3 5% (v/v), 0,5mL de xileno e 2 mL de uma mistura dos solventes n-Propanol/ Triton X-100 na propor??o 5:1. A massa de amostra de petr?leo foi de cerca de 0,20g. Magn?sio foi usado como precursor da mol?cula de MgCl, e a concentra??o otimizada foi de 10 g L-1. Os estudos da propor??o entre Mg e Cl para favorecimento da forma??o da mol?cula mostraram que para garantir a m?xima forma??o da mol?cula de MgCl ? necess?rio utilizar uma raz?o em massa de pelo menos 500 Mg:1 Cl. Uma massa de 5 ?g de Pd foi introduzida ? cada ciclo de inje??o como modificador qu?mico, para aumentar a estabilidade t?rmica da esp?cie molecular. As temperaturas de pir?lise e vaporiza??o otimizadas foram 800 ?C e 2300 ?C, respectivamente. Para an?lise de cloro, foram utilizadas oito amostras de petr?leo da Bacia Potiguar e dois materiais de refer?ncia certificados, ?leo lubrificante aditivado (NIST 1848) e a de ?leo combust?vel (NIST 1634c), foram utilizados para a verifica??o da exatid?o do m?todo. A estrat?gia de calibra??o contra padr?es aquosos foi poss?vel, obtendo-se o LOD de 5 mg kg-1. Testes de adi??o/recupera??o foram realizados e os valores obtidos ficaram na faixa entre 92 e 117%. A metodologia proposta mostra-se simples, r?pida com preparo de amostra simplificado. / Chloride is considered an important contaminant of petroleum as it interferes with the process of transportation and refining and can be transferred to the final product derivatives. During refining, the presence of chloride may lead to the formation of HCl, causing serious corrosion problems. A methodology for the determination of chlorine in petroleum samples prepared by emulsions was developed by high resolution molecular absorption spectrometry with continuum source through the diatomic molecule MgCl, in the wavelength 377.01 nm. The preparation of the emulsion was optimized through centroid-simplex design. The conditions of preparation of the emulsions were: 0.5 mL of 5% (v / v) HNO3, 0.5 mL of xylene and 2 mL of a mixture of n-Propanol / Triton X-100 solvents in the ratio 5:1. The crude oil mass used was about 0.20 g. Magnesium was used as the precursor of the molecule, the optimized concentration was 10 g L-1. The proportional studies between Mg and Cl for the formation of molecules show that to ensure the formation of a MgCl molecule is required for a mass ratio of at least 500 Mg: 1 Cl. A mass of 5 ?g of Pd was introduced at each cycle that chemical modifier for increase the thermal stability of the molecular species. The optimized pyrolysis and vaporization temperatures were 800 ? C and 2300 ? C, respectively. For chlorine analysis, eight crude oil samples from the Potiguar Basin and two certified reference materials, lubricated oil (NIST 1848) and fuel oil (NIST 1634c) were used, to verify the accuracy of the method. The calibration strategy against aqueous standards was possible, obtaining the LOD of 5 mg kg-1. Addition / recovery tests were performed and the values obtained were between 92 and 117%, values acceptable analytically. The proposed methodology is simple, fast with simplified sample preparation.
24

O p?lo sindical do subm?dio S?o Francisco: das lutas por reassentamento ? incorpora??o do cultivo de maconha na agenda

RIBEIRO, Ana Maria Motta 29 February 2008 (has links)
Made available in DSpace on 2016-04-28T20:19:53Z (GMT). No. of bitstreams: 1 2008 - Ana Maria Motta Ribeiro.pdf: 1483676 bytes, checksum: f690f9b834362b5dbb0eb9c9597a9fbd (MD5) Previous issue date: 2008-02-29 / This paper tries to analyze, in a critical way, the syndicalism in the Polo Sindical do Subm?dio S?o Francisco, inserted in a region identified by the Press as the Hemp Polygon. It intends to understand, from the field work, the insertion of the subject of the hemp plantation (criminalized) in the agenda of the Polo Sindical do Subm?dio S?o Francisco. The study intends to understand this phenomenon through a historical retrospection and an analysis about the region understood as a social-political production of territorialities. Also, it develops an attempt of explanation of the crossing between illegal agriculture and the dynamic of syndical struggle for the recovery of the version which the entity produces and legitimates as its biography in order to understand how and by whom the justification of that crossing is built. In this process of sociological undoing of the Hemp Polygon, it is shown how, when and through which means the subject of the illegal cultivation enters the agenda of the entity. / Esta TESE tenta analisar de modo cr?tico o sindicalismo do P?lo Sindical do Subm?dio S?o Francisco inserido numa regi?o identificada pela M?dia como o Pol?gono da Maconha . Pretende compreender, a partir de pesquisa de campo, a entrada do tema do plantio de maconha (criminalizado) na agenda do P?lo Sindical do Subm?dio S?o Francisco. O estudo pretende entender esse fen?meno atrav?s de uma retrospectiva hist?rica e de uma an?lise sobre a regi?o entendida como uma produ??o s?cio pol?tica de territorialidades. Tamb?m desenvolve uma tentativa de explica??o do cruzamento entre agricultura il?cita e a din?mica da luta sindical, pela recupera??o da vers?o que a entidade produz e legitima como sua biografia para entender como ? elaborada e por quem, a justificativa desse cruzamento. Neste processo de desconstru??o sociol?gica do Pol?gono da Maconha, se destaca como, quando e atrav?s de que media??es o tema do cultivo il?cito entra na agenda da entidade.
25

Klavírní dílo Alexandra Moyzese (1906-1984) v dobovém kontextu / Piano Works by Alexander Moyzes (1906-1984) in their Historical Context

Čerbová, Zuzana January 2017 (has links)
The magister thesis is connected with bachelor's thesis, which was concentrated on Piano Sonata in E minor, op. 2 by Slovak composer Alexander Moyzes (1906-1984) and was concerned on it mainly with collected sources. In this thesis we decided to point out its composing work and possible inspiring sources and therefore the focus of this diploma thesis is its introduction into historical context of piano music of the 19th and 20th centuries. Through composite-technical and stylistic analyses of selected piano sonatas and other works, we want to contribute to the closer characterization of Moyzes composer's personality and to complement the literature that Moyzes Sonate has devoted to in minimal terms from composing work and inspiring sources. Selected pieces include: Brahms Sonata f mol, Op. 5 and Variation and Fugue on a Theme by Handel, op. 24 from the point of view of means of piano stylization, Sonata Eroica, op. 24 for piano by Vít zslav Novák because of their mutual interest in working with modality and mutual close relationships (Moyzes's teacher). In addition to these goals, we will also focus on the other piano works of Moyzes by creating a new chronological inventory based on preserved sources. Key words: Alexander Moyzes, Piano Sonata in E minor op. 2, Johannes Brahms, Vít zslav Novák,...
26

Who hacked my toaster? : A study about security management of the Internet of Things. / Vem har hackat min brödrost? : En studie om säkerhetshantering av Internet of Things

Hakkestad, Mårten, Rynningsjö, Simon January 2019 (has links)
The Internet of Things is a growing area with growing security concerns, new threat emerge almost everyday. Keeping up to date, monitor the network and devices and responding to compromised devices and networks are a hard and complex matters.  This bachelor’s thesis aims to discover how a IT-company can work with security management within the Internet of Things, this is done by looking into how a IT-company can work with updating, monitoring and responding within the Internet of Things, as well what challenges there are with working with this.  A qualitative research approach was used for this case study along with an interpretative perspective, as well as abductive reasoning. Interviews were performed with employees of a large IT-company based in Sweden, along with extensive document analysis.  Our bachelor’s thesis results in challenges with Security Management within the areas updating, monitoring and responding along with how our Case Company works with these security challenges. Largely these challenges can be summarized that everything is harder with the number of devices there are within the Internet of Things / Internet of Things eller Sakernas internet är ett växande område med en växande hotbild och nya hot uppkommer dagligen. Att hålla sig uppdaterad, övervaka nätverk och enheter samt att reagera på att enheter och nätverk blir hackade är en svår och komplicerad uppgift. Den här uppsatsen ämnar undersöka hur ett IT-företag kan arbeta med säkerhetshantering inom Internet of Things. Detta har gjorts genom att kolla utmaningar och säkerhetslösningar inom de tre områdena uppdatera, övervaka och reagera.  En kvalitativ forskningsmetod har använts i denna fallstudie tillsammans med ett tolkande synsätt och en abduktiv ansats. Vi har utfört intervjuer på ett stort IT-företag baserat i Sverige tillsammans med en utförlig dokumentanalys.  Resultatet av denna uppsats påvisar ett antal utmaningar inom säkerhetshanteringen inom områdena uppdatera, övervaka och reagera tillsammans med hur vårt fallföretag jobbar med att motarbeta dessa utmaningar. I stort sett kan utmaningarna sammanfattas till att allting är svårare när mängden enheten är så hög som den är inom Internet of Things.
27

Express?o imuno-histoqu?mica das integrinas ?2?1, ?3?1, e ?5?1, em mucosa oral normal, hiperplasia fibroepitelial inflamat?ria oral e displasia epitelial oral

Gord?n N??ez, Manuel Antonio 18 August 2006 (has links)
Made available in DSpace on 2014-12-17T15:32:31Z (GMT). No. of bitstreams: 1 ManoelAGN_tese.pdf: 5283581 bytes, checksum: 65511a1dd2487deff44e8db44d2a0cf5 (MD5) Previous issue date: 2006-08-18 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The objective of this study was perform by the streptoavidin-biotin technique an immunohistochemical analysis of ?2?1, ?3?1e ?5?1 integrins in 11 normal oral mucosa (NOM), 16 oral inflammatory fibroepithelial hyperplasia (OIFH) and 25 oral epithelial dysplasia (OED) (16 mild, 2 moderates and 7 severe), to determine if exists qualitative alteration in the expression of these integrins and if this guard relation with the oral epithelial modifications. It was observed that for the ?2?1 integrin the majority of the sample showed a predominantly intense labeling diffusely distributed in the intercellular contacts and the cytoplasm of cells of the basal and suprabasal layers, without difference of this profile between the different types of specimens, however with a trend to weak or loss of expression in 21.1% of the OEDs, being all the specimens that had not expressed this heterodimer, severe OEDs. For the ?3?1 integrin the majority of the sample showed a weak or absent labeling in basal layer. The ?5?1 integrin showed a predominant strong diffuse labeling in the intercellular contacts and cytoplasm in the suprabasal layer, with difference only in the labeling intensity between the types of specimens, inhabiting this difference in the OEDs, where 12 (48%) specimens had shown a weak labeling. It was concluded that the evaluated integrins can be involved in the cell-cell, cell-ECM interactions modulating the cellular differentiation and maintenance of the epithelial structural arrangement. The variable expression of the ?5?1 integrin in the OEDs, could suggest, respectively, a role of this molecule in the cellular survival, with intention to perpetuate the modified phenotype in these lesions, or a suppressor role on the modified phenotype due to lack of interaction of this molecule with the fibronectina of the MEC / Este estudo se prop?s analisar atrav?s da t?cnica da estreptoavidina-biotina a express?o imuno-histoqu?mica das integrinas ?2?1, ?3?1e ?5?1 em 11 esp?cimes de mucosa oral normal (MON), 16 de hiperplasia fibroepitelial inflamat?ria oral (HFIO) e 25 de displasia epitelial oral (DEO) (16 leves, 2 moderadas e 7 graves), procurando determinar se existe altera??o qualitativa na express?o destas integrinas e se a mesma guarda rela??o com as modifica??es sofridas pelo epit?lio oral. Para a integrina ?2?1 a maioria dos esp?cimes exibiu uma marca??o predominantemente intensa e difusa nos contatos intercelulares e no citoplasma celular das camadas basal e suprabasal, sem diferen?a desse perfil entre os diferentes tipos de esp?cimes, por?m com uma tend?ncia a fraca ou perda da express?o em 21.1% das DEOs, sendo todos os esp?cimes que n?o expressaram marca??o para este heterod?mero DEOs graves. Para a integrina ?3?1 a maioria da amostra exibiu uma marca??o fraca ou ausente predominantemente em camada basal. A integrina ?5?1 exibiu uma forte marca??o difusa nos contatos intercelulares e citoplasm?tica na camada suprabasal, com diferen?a apenas na intensidade de marca??o entre os tipos de esp?cimes, residindo essa diferen?a nas DEOs, onde 12 (48%) esp?cimes exibiram uma fraca marca??o. Concluiu-se que as integrinas avaliadas podem estar envolvidas nas intera??es c?lula-c?lula e c?lula-MEC que garantem a diferencia??o celular e manuten??o do arranjo estrutural tecidual. A vari?vel express?o da integrina ?5?1 nas DEOs, poderia sugerir, respectivamente, um papel dessa mol?cula na sobrevida celular, com o intuito de perpetuar o fen?tipo alterado nessas les?es, ou uma a??o supressora desse fen?tipo devido ? falta de intera??o desta mol?cula com a fibronectina da MEC
28

Liquid Natural Gas : A study of the environmental impact of LNG in comparison to diesel / Flytande Naturgas : En studie om LNG:s klimatpåverkan i jämförelse med diesel

Edfors, Jonas, Bremberg, Robin January 2021 (has links)
Liquefied Natural Gases (LNG) has been an alternative fuel in the marine industry for several years, but lately, the amount of ships that have been powered by methane has increased a lot. Some of the reasons for this is because LNG does not contain any sulfur and releases less nitrogen oxides than traditional maritime fuels. In this essay, LNG will be compared to diesel from an environmental perspective with focus on CO2 emissions and its equivalents. International Maritime Organization (IMO) implemented Energy Efficiency Design Index (EEDI) requirements that adjusts how much CO2 is allowed in the exhaust gas per produced kilowatt-hour (kWh). However, these requirements will increase in intervals in the future, the next one is coming 2022 for specific ship types. The method that is used to compare the fuels is Mole-calculations for LNG as well as diesel, then calculate the amount of carbon dioxide (CO2) and its equivalents they release. The results show that under optimal conditions, LNG was the superior choice. However, the maritime industry might have a problem with the requirements that will be introduced to greenhouse gas (GHG) emissions in 2050. / Flytande Naturgas (LNG) har under flera år funnits som ett alternativt bränsle inom sjöfarten, men på senare tid så har skeppen som drivs av metan ökat markant. En anledning till detta är att LNG innehåller inget svavel samt släpper ut mindre NOX jämfört med traditionella bränslen. I denna uppsats så kommer LNG att jämföras mot diesel ur ett klimatperspektiv med fokus på koldioxidutsläpp och dess ekvivalenter. International Maritime Organisation (IMO) har infört Energy Efficiency Design Index (EEDI) krav som justerar hur mycket CO2 man får släppa ut per kilowattimme (kWh), dessa krav kommer dessutom att öka i flertalet intervaller i framtiden, varav nästa intervall redan sker i 2022 för speciella fartygstyper. Metoden som användes för att jämföra bränslena var att beräkna mol-innehållet för både LNG samt diesel, sen från den beräknade data se hur mycket koldioxid (CO2) inklusive ekvivalenter de släppte ut. Resultatet visade att under optimala förutsättningar så var LNG ett klart bättre alternativ än diesel. Däremot så kan sjöfarten ha ett problem inom framtiden från de krav som berör växthusgaser som kommer att ställas från och med 2050.

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