• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 46
  • 43
  • 18
  • 13
  • 9
  • 6
  • 4
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 168
  • 34
  • 28
  • 17
  • 17
  • 15
  • 12
  • 12
  • 11
  • 11
  • 10
  • 10
  • 9
  • 9
  • 9
  • 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.
31

Modeling of CO2 separation in post-combustion processes by PSA / Modelagem da separaÃÃo de CO2 em processos de pÃs-combustÃo por PSA

Hugo Rocha Peixoto 23 February 2015 (has links)
CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Adsorption processes involving carbon dioxide (CO2) capture and sequestration have been objects of different studies. A typical problem is the separation of CO2 from fuel gases emitted in power plants in order to mitigate the global warming effects. Recently, Pressure Swing Adsorption (PSA) technology is being applied to this separation. However, design and analysis of adsorption processes are a difficult task due to the large number of parameters involved. This work studies the dynamics of this separation in activated carbons C141 and WV 1050 through commercial software Aspen Adsorption (AspenTechÂ). First, we evaluated the ability of the software reproducing experimental fixed bed data in C141 reported on literature, considering the mixture 10% of helium (carrier gas), 15% dioxide carbon and 75% nitrogen, molar basis. The results showed satisfactory resemblance to the literature. From a scale-up of the analyzed system, it was sized a PSA apparatus at 298 K operating with two columns and four steps: adsorption, depressurization, purge and repressurization (Skarstrom cycle). High-pressure step was at 3.0 bar and regeneration at 1.1 bar. Fuel gas mixture simulated was composed only of CO2 and N2; the molar fraction of the first component at the feed stream was 15%. The product stream in C141 showed purity and recovery of carbon dioxide from approximately 23% and 60% on a molar basis, respectively. The productivity was 0.72 t CO2 kg-1 year-1. Through the study of design variables such as column diameter and length, feed and purge flow rate, feed composition and step times, the product purity exceeded 30 % and the recovery bordered 75%, with maximum productivity of 1.02 t CO2 kg-1 year-1 for some process settings. The process yields in WV 1050 were 26.5 % purity, 47 % recovery and 0.53 t CO2 kg-1 year-1. / Processos de adsorÃÃo envolvendo a captura e o sequestro de diÃxido de carbono (CO2) vÃm sendo objetos de diferentes estudos. Um dos problemas tÃpicos analisados à a separaÃÃo do CO2 a partir dos gases de queima emitidos em plantas energÃticas com o intuito de mitigar os efeitos do aquecimento global. Recentemente, a tecnologia Pressure Swing Adsorption (PSA) està sendo aplicada para este tipo de separaÃÃo. Entretanto, o projeto e a anÃlise de processos de adsorÃÃo sÃo uma tarefa difÃcil devido à grande quantidade de parÃmetros envolvidos. Este trabalho estuda a dinÃmica dessa separaÃÃo nos carbonos ativados C141 e WV 1050 atravÃs do software comercial Aspen Adsorption da AspenTechÂ. Inicialmente, foi avaliada a capacidade do software no que diz respeito à reproduÃÃo de dados experimentais de leito fixo reportados na literatura, que consideram a mistura como sendo, em base molar, 10 % de hÃlio (gÃs de inerte), 15 % de diÃxido de carbono e 75 % de nitrogÃnio. Os resultados obtidos apresentaram semelhanÃa satisfatÃria aos da literatura para o sÃlido C141. A partir de um scale-up desse sistema analisado, foi dimensionada uma PSA a 298 K de duas colunas e quatro passos: adsorÃÃo, despressurizaÃÃo, purga e repressurizaÃÃo (ciclo Skarstrom). A etapa de maior pressÃo ocorre a 3,0 bar e a regeneraÃÃo a 1,1 bar. Considerou-se que o gÃs de queima à composto apenas por CO2 e N2, sendo a fraÃÃo molar de alimentaÃÃo do componente de interesse de 15%. Para C141, a corrente de produto apresentou pureza e recuperaÃÃo de diÃxido de carbono de aproximadamente 23 % e 60 % em base molar, respectivamente, com produtividade de 0,72 t CO2 kg-1 ano-1. AtravÃs do estudo de variÃveis de projeto como diÃmetro e comprimento da coluna, vazÃo de alimentaÃÃo e de purga, composiÃÃo de alimentaÃÃo e tempos das etapas do ciclo, a pureza do produto ultrapassou os 30 %, a recuperaÃÃo se aproximou de 75 % e a produtividade mÃxima foi de 1,02 t CO2 kg-1 ano-1 para algumas configuraÃÃes do processo. Os rendimentos para o adsorvente WV 1050 foram: pureza de 26,5 %, recuperaÃÃo de 47 % e produtividade de 0,53 t CO2 kg-1 ano-1.
32

Lean : En fallstudie om Lean på Statoil

Choukeir, Tarek, Papadopoulos, Alexandra January 2011 (has links)
No description available.
33

Determination of Polymer Film Development through Surface Characterization Studies

Fike, Gregory Michael 01 April 2005 (has links)
Unexpectedly, it was found that when a waterborne polyacrylate adhesive was placed on carbon steel it was not tacky; this was not the case for the same adhesive placed on stainless steel. It was determined that the surface energy, as measured with liquid contact angles, of the adhesive films is significantly different between the two films, with the non-tacky film having a higher surface energy. Atomic force microscopy (AFM) showed that the non-tacky surface has a higher roughness which minimizes the contacting area between the film and a contacting surface. Analysis of the heating of the carbon steel coupon with infrared thermography shows a non-uniform temperature profile at the surface. This experimental data is corroborated using a 2-D heat transfer model that incorporates the heat transfer characteristics of the various components of carbon steel. Surface driven flow, or Marangoni convection, can develop from temperature gradients and are known to cause increased roughness in polymer films. IR thermography measurements of the adhesive film during drying shows larger temperature differences for the films on carbon steel than on stainless steel. These larger temperature differences induce greater Marangoni convection, which result in the rougher surfaces on carbon steel that were measured with AFM. The effect of lowering the tack of a polyacrylate film has significant impact in the dryer section of a paper machine. This effect was quantified using the Web Adhesion Drying Simulator, which is a laboratory-scale apparatus that measures the energy required to pull the sheet from a metal surface. By substituting the adhesive-on-stainless steel with the less-sticky adhesive-on-carbon steel surface, the energy required to pull the sheet from the metal surface was reduced significantly and the picking associated with the test was nearly eliminated.
34

none

Cheng, Shu-Hui 05 August 2002 (has links)
Abstract Recently the competition among ports has become more severely. This may develop to a new stage of competition of port management as the negotiation of the marine to be restarted in the WTO. What kind of port services could be provided is very critical to those who operate and manage the port. It is important for them to think about how to evaluate and get into the newly opened market of port services. During the stage of organization reform of Kaohsiung port, especially if we could hold this chance, it may create a new development opportunity for Kaohsiung port. PSA group is operating its port in full service and integration; therefore, my research focus is on PSA group¡¦s performance using industrial organization model to analyze its operational environment, and collecting the investigation from ship owners, employees of Harbor Bureau, pilots and scholars. This is done so in regards to the important port services and management condition to come up the core competence of the port. The paper focuses on the investigation of Singapore, Hong Kong and Kaohsiung port to know the merit and analyze the SWOT of PSA¡¦s managing strategy by the statistics sign test. Then, using this concept of basic source model, to find PSA¡¦s management strategy, which upgraded its competition ability, and made the superior position to develop overseas business. ¡uWe can find the right way by other¡¦s experience.¡v, The experience of PSA¡¦s group is good for Kaohsiung Port.
35

Dissecting the heterogeneity of prostate cancer cells

Liu, Xin, active 2013 07 November 2013 (has links)
Prostate cancer (PCa) is heterogeneous containing phenotypically diverse cells. It is unclear whether these phenotypically different PCa cells are functionally distinct and possess divergent tumorigenic potential. Androgen signaling plays important roles in differentiation and survival of malignant PCa cells, and prostate specific antigen (PSA) as one of the androgen signaling target genes is used as a biomarker of AR signaling to assess tumor progression and evaluate therapeutic efficiency in clinic. Here we present evidence for discordant AR and PSA expression resulting in AR⁺/PSA⁺, AR⁺/PSA⁻, AR⁻/PSA⁻, and AR⁻/PSA⁺ PCa cells in human tumors. We also show that prostate tumor PSA mRNA levels inversely correlate with poor clinical outcomes and patient survival. By employing a lentiviral reporter system, we have fractionated bulk PCa cells into PSA⁺ and PSA⁻[superscript '/lo'] cell populations, with the former being AR⁺/PSA⁺ and the latter containing both AR⁺/PSA⁻ and AR⁻/PSA⁻ cells. The PSA⁺ and PSA⁻[superscript '/lo'] PCa cells demonstrate distinct molecular, cellular, and tumor-propagating properties. PSA⁻[superscript '/lo'] PCa cells are quiescent and refractory to stresses including androgen deprivation, exhibit high clonogenic potential, and possess long-term tumor-propagating capacity. They preferentially express stem cell genes and can undergo asymmetric cell division to generate PSA⁺ cells. Of great clinical interest, PSA⁻[superscript '/lo'] PCa cells can initiate robust tumor development and resist androgen ablation in castrated hosts, and they harbor highly tumorigenic castration resistant PCa cells. In contrast, PSA⁺ PCa cells possess more limited tumor-propagating capacity, undergo symmetric division, and are sensitive to castration. Systemic androgen levels dynamically regulate the relative abundance of PSA⁺/PSA⁻[superscript '/lo'] PCa cells in the tumors, which in turn impact the kinetics of tumor growth. Further studies reveal that the PSA⁻[superscript '/lo'] PCa cell population harbors several overlapping but nonidentical tumorigenic subsets including ALDH⁺, CD44⁺, and [alpha]2[beta]1⁺ cells and ALDH⁺CD44⁺[alpha]2[beta]1⁺ can further enrich castration resistant PCa cells. These observations together suggest that heterogeneous PCa cells are organized as a tumorigenic hierarchy. Our results have important implications in understanding how different subpopulations of PCa cells manifest differential responses to current androgen deprivation therapy (ADT). / text
36

Separação adsortiva de misturas etanol-água por processo PSA.

Moreira, Alexandre Marques 02 March 2005 (has links)
Made available in DSpace on 2016-06-02T19:56:59Z (GMT). No. of bitstreams: 1 DissAMM.pdf: 1945898 bytes, checksum: afb882ff1ea5d0b744547e87dfa2e263 (MD5) Previous issue date: 2005-03-02 / Financiadora de Estudos e Projetos / The ethanol is one of the most well-known and diffused fuels sources in nowadays, therefore the domain of its technology has a great importance to the producer countries. Beyond it is in general, lesser expensive than the major part of the petrochemical fuels, the ethanol has its origin in the renewable sources that becomes Brazil in a world power on its production. From these facts the present work consists on the application of the PSA (Pressuring Swing Adsorption) process on the ethanol purification, from ethanol-water mixtures with compositions that simulate ethanol concentrations of the final steps of distillation process. To get this ethanol purification it was used the zeolite 3A as adsorbent, which adsorbed the water of the mixtures in a pressured bed. The PSA process were composed by four steps: The first was the adsorption bed pressurization, at high temperature, with a given ethanol-water mixture; the second was the residence of the fed mixture for a given time in the bed to recover the ethanol; the third was the depressurisation of the bed to the ambient pressure, and the fourth was the regeneration of the adsorbent by vacuum, to recover the water adsorbed. The process variables studied in this work were adsorption pressure, adsorption time and initial concentration, being evaluated their influences on the response variables fluid phase enrichment, ethanol recover and process productivity, were studied, through a factorial planning. These influences were described by polynomial models, in which were applied the statistical tests F and R2, to analyse the quality of the obtained adjustments. The obtained models were validated by extra experiments done out of the factorial planning. The influences of the process variables over the response variables were analysed through response surfaces generated by the obtained polynomial models. The response variables were individually optimized with the using of search programs, which sought the best results over the polynomial models and the process variable ranges. The individual optimum results of the response variables were found, at the same way, the values of the process variables that produced these results. The response variables were also optimized together simultaneously. To obtain these optimizations search programs, with the same logic of the used in the individual optimization, were used with the multiresponse method, which made possible the obtainment of the optimum values of response variable arrangements in pairs and all of these together simultaneously. These optimum values to these arrangements were obtained, at the same way that the process variable values, which correspond to these optimizations. The enrichment obtained results showed high values and low variations with the increase of the adsorption time. At the same way, the adsorption pressure influences the enrichment significantly only with low values of the initial concentration and adsorption time. The enrichment had also an increase of its value and a decrease of its variation, with the increase of the initial ethanol concentration. The ethanol recover showed without significantly influence with the variations of the adsorption time and the adsorption pressure, however had an increase with the increase of the initial concentration. The productivity profiles showed that they were influenced by the three process variables. The increase of the productivity was detected with the increase of the initial concentration and the increase of the adsorption pressure. The productivity decreased with the increase of the adsorption pressure. The obtained results to the simultaneous optimizations showed that the productivity had a predominant influence over the other response variables optimized with these. At the same way, the recover values were not influenced by the optimization of the others response variables. Also it was seen that the enrichment optimization impaired the productivity results, in spite of the reverse fact had not been verified. To illustrate the generated results of the optimizations, the next values were obtained to the optimization of the three response variables simultaneously: 94.7% to the fluid phase enrichment, 82.5% to the ethanol recover and 5.14g.g-1.h-1 to the process productivity, with the values of the process variables of 10 bar to the adsorption pressure, 90% to the initial ethanol concentration and 2.0 minutes to the adsorption time. / O etanol é uma das fontes combustíveis mais conhecidas e difundidas na atualidade, sendo então de grande importância o domínio de sua tecnologia para os países produtores. Além de ser um combustível, em geral, de custo inferior à maioria dos derivados petroquímicos, o etanol é proveniente de fontes totalmente renováveis, tornando o Brasil uma potência mundial na sua produção. Desta forma o presente trabalho trata do estudo da aplicação do processo PSA (Pressuring Swing Adsorption) na purificação do etanol a partir de misturas etanolágua com composições simulando às encontradas no final do processo de destilação convencional. Para isso foi utilizado o adsorvente comercial zeólita 3A, promovendo a adsorção da água em um leito pressurizado. O processo PSA empregado consistia basicamente de quatro etapas: A primeira se dava com a pressurização, a alta temperatura, do leito adsorvente com uma determinada mistura de etanol-água; a segunda consistia na permanência da mistura no leito durante um tempo pré-estabelecido; a terceira consistia na despressurização do leito até a pressão ambiente para a retirada do etanol, e a quarta se dava pela regeneração do adsorvente através de vácuo aplicado ao leito, para a retirada da água. As variáveis de processo estudadas neste trabalho foram pressão de adsorção, concentração inicial de alimentação e tempo de adsorção, sendo avaliadas suas influencias sobre as variáveis resposta enriquecimento da fase fluida, recuperação de etanol e produtividade do sistema, a partir de experimentos elaborados através de um planejamento fatorial. Estas influências foram descritas por modelos polinomiais, nos quais foram aplicados os testes de avaliação estatística F e R2, a fim de analisar a qualidade dos ajustes obtidos, além de terem sido obtidos pontos experimentais extras utilizados para a validação dos modelos obtidos. As influências das variáveis de processo sobre as variáveis resposta foram visualizadas através de superfícies resposta geradas a partir dos modelos polinomiais obtidos. As variáveis resposta forma otimizadas individualmente a partir de programas de busca, os quais varriam as faixas de valores adotadas pelas variáveis de processo estudadas, sendo portanto encontrados os valores ótimos individuais de cada variável resposta, assim como os valores das variáveis de processo necessários para a obtenção destes ótimos. As variáveis resposta também foram otimizadas em conjunto, simultaneamente. Para isto também foram utilizados programas de busca, aplicando-se o método de otimização multiresposta, o qual possibilitava a obtenção de valores ótimos combinando-se as variáveis resposta em pares e todas simultaneamente. Estes valores ótimos foram obtidos, assim como os valores das variáveis de processo correspondentes a estas otimizações. Os resultados obtidos para o enriquecimento da fase fluida mostraram um maior valor e uma menor variação deste com o aumento no tempo de adsorção; assim como a existência de variação significativa deste com a pressão de adsorção apenas para valores baixos de concentração inicial e tempo de adsorção. O enriquecimento teve também um aumento em seu valor, acompanhado de uma diminuição de variação com o aumento da concentração inicial de etanol. A recuperação de etanol mostrou-se não ser influenciada pelo tempo de adsorção e pela pressão de adsorção, havendo um aumento desta variável resposta apenas com o aumento da concentração inicial de etanol. Os comportamentos da produtividade se mostraram influenciáveis por todas as variáveis de processo. Houve aumento da produtividade com o aumento da concentração inicial de etanol e com o aumento da pressão de adsorção, havendo também diminuição da produtividade com o aumento do tempo de adsorção. Os resultados obtidos nas otimizações simultâneas mostraram que a produtividade teve influencia predominante frente às outras variáveis em combinação com esta, assim como os valores da recuperação não foram influenciados pelas otimizações das outras variáveis. Foi constatado também que a otimização do enriquecimento comprometeu os resultados de produtividade, onde o contrário não foi verificado. Como exemplo dos resultados gerados pelas otimizações, foram obtidos os seguintes valores para a otimização de todas as variáveis resposta em conjunto: 94,7% de enriquecimento, 82,5% de recuperação e 5,14g.g-1.h-1 de produtividade, com a combinação das variáveis de processo de 10 bar para a pressão de adsorção, 90% para a concentração inicial de etanol e 2,0 minutos para o tempo de adsorção.
37

Uso de carvões ativados modificados por soluções alcalinas na separação de CH₄/CO₂ para enriquecimento do biogás

ACCIOLY, Paula Lobo 08 June 2017 (has links)
Submitted by Pedro Barros (pedro.silvabarros@ufpe.br) on 2018-08-28T22:54:10Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Paula Lobo Accioly.pdf: 3604355 bytes, checksum: 04c452fb98abcccc8a86d838ea82aa1d (MD5) / Approved for entry into archive by Alice Araujo (alice.caraujo@ufpe.br) on 2018-09-06T17:29:13Z (GMT) No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Paula Lobo Accioly.pdf: 3604355 bytes, checksum: 04c452fb98abcccc8a86d838ea82aa1d (MD5) / Made available in DSpace on 2018-09-06T17:29:13Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Paula Lobo Accioly.pdf: 3604355 bytes, checksum: 04c452fb98abcccc8a86d838ea82aa1d (MD5) Previous issue date: 2017-06-08 / CAPES / O biogás é um biocombustível oriundo da decomposição de substratos orgânicos biodegradáveis. A energia resultante do biogás é muito importante, uma vez que é uma fonte alternativa ao gás natural, reduzindo-se os impactos ambientais associados as emissões excessivas de gás carbônico na atmosfera. Em geral, a composição do biogás varia de 40-75% de CH₄, 15-60% (v.v⁻¹) de CO₂ e impurezas. Em virtude do alto teor de CH₄, é possível enriquecer esse biocombustível removendo-se o gás carbônico e, por conseguinte, elevando-se o percentual volumétrico de CH₄. O enriquecimento do conteúdo de CH₄ produz o biometano, substituto renovável do gás natural. A separação entre CH₄/CO₂ do biogás é plausível através da adsorção sob variação de pressão (PSA, Pressure Swing Adsorption). Um importante fator dessa tecnologia é o adsorvente e dentre vários materiais em uso há o carvão ativado (AC). O AC tem boas características texturiais, baixo custo e é de produção simples, no entanto outros adsorventes apresentam capacidades adsortivas de gás carbônico superiores ao AC. Considerando que o CO₂ tem característica ácida, impregnou-se o AC em soluções de hidróxido de K, Ca e Mg a 1,0M e Na a 1,0 e 0,1M, separadamente para melhorar a capacidade de adsorção de CO₂ do carvão ativado puro. A pesquisa consistiu em comparar as características dos carvões modificados, as capacidades dinâmicas de CO₂ e avaliar a dinâmica de adsorção de gás carbônico na coluna com o carvão de melhor desempenho adsortivo de CO₂. O sistema consistiu em coluna adsorvedora com 28mm de diâmetro e 187mm de altura que operou a temperatura, pressão e vazão de mistura gasosa semelhante ao biogás de 0,1MPa, 297 K e 0,0033L.s⁻¹, nessa ordem. Os resultados das caracterizações demonstram que a impregnação alcalina reduziu as propriedades texturiais dos carvões ativados. A dinâmica de adsorção exibe a retenção de CO₂ e a difusão de CH₄ por entre o leito para todos os carvões. As análises das capacidades de adsorção de CO₂ exibem a seguinte ordem crescente dos AC em relação à carga de CO₂, a pressões parciais de CO₂ maiores que 0,04MPa: AC-Mg(OH)₂(1,0M)<AC-KOH(1,0M)<AC<AC-NaOH(0,1M), com capacidades de CO₂ de 0,62 0,80, 0,96 a 0,05MPa e 1,29mol.kg⁻¹ a 0,04MPa, respectivamente. Portanto, o carvão ativado tratado em hidróxidos de sódio a 0,1M têm maior capacidade de CO₂ em relação ao AC puro. A modelagem da isoterma de adsorção de CO₂ para o AC-NaOH(0,1M) permitiu a determinação da capacidade máxima de adsorção desse gás de 2,57mol.kg⁻¹. A modelagem da transferência de CO₂ resultou em perfis de concentração que reproduzem os dados experimentais. Essa pesquisa tem relevância, pois contribui ao desenvolvimento de adsorventes e processos adsortivos mais eficientes para remoção do dióxido de carbono em mistura de CH₄/CO₂, promovendo o melhoramento da tecnologia PSA e o refino de biogás. / Biogas is a biofuel produced from the anaerobic decomposition of organic matter. Energy from biogas is very important once it is an alternative to fossil fuel energy and it is renewable, which reduces environmental impacts relative to extreme emissions of carbon dioxide to the atmosphere. In general, biogas composition consists of 40-75% (v.v⁻¹) of CH₄, 15-60% (v.v⁻¹) of CO₂ and impurities. In virtue of its high methane load, it is possible to enhance biogas by the removal or reduction of its carbon dioxide and, hence, increase its volumetric percentage of methane to 95% or more. This methane enrichment results in the production of biomethane that is a renewable natural gas. Biogas methane/carbon dioxide separation is plausible by Pressure Swing Adsorption (PSA). An important factor to this technology is the type of adsorbent used and among many materials is the activated carbon (AC). ACs have good textural characteristics, they are inexpensive, and of simple production, however other adsorbents have higher carbon dioxide adsorption capacity. Due to the carbon dioxide acid characteristic, AC was submitted to impregnation with hydroxide solutions of K, Ca, Mg 1.0M and sodium hydroxide at 0.1 and 1.0M solutions, separately in order to improve unmodified AC CO₂ adsorption capacity. The research objective consisted in comparing the AC characteristics, assessing the carbon dioxide dynamic capacity and evaluate the adsorption dynamics while using a packed bed column adsorber. The adsorption system consists of a packed-bed column with 28mm of diameter and 187 mm in height, which operated at pressure, temperature and in-gas flow similar to biogas of 0.1MPa, 297K and 0.0033L.s⁻¹, respectively. The characterization results demonstrated that alkaline impregnation of the AC reduced the textural properties of the AC. The adsorption studies exhibited the capture of carbon dioxide and the diffusion of methane gas through the packed bed for all the AC. The evaluation of the carbon dioxide capacity of each AC suggests the following increasing order of the AC regarding the load of CO₂, at partial pressures superior to 0,04MPa: AC-Mg(OH)₂(1,0M)<AC-KOH(1,0M)<AC<AC-NaOH(0,1M), with CO₂ capacity of 0,62, 0,80, 0,96 at 0,05MPa and 1,29mol.kg⁻¹ at 0,04MPa, respectively. Therefore, activated carbons modified with sodium hydroxide obtained a higher carbon dioxide capacity in relation to the pure activated carbon. By modeling the carbon dioxide isotherm for the AC-NaOH(0,1M) the maximum capacity was determined, which is 2,57mol.kg⁻¹. The adsorbate mass transfer was also modeled and the simulation of the concentration profiles reproduced the experimental results. This research is relevant, in which it contributes to the elaboration of adsorbents and operation of packed bed adsorption process for a more efficient carbon dioxide capture from CH₄/CO₂ mixture, and thus promotes the PSA technology and the production of biomethane.
38

Osäkerhetsanalys av PSA-resultat : Metodutveckling och parameterinventeringför osäkerhetsanalys av PSA-resultat

Eriksson, Carl January 2017 (has links)
This master thesis examines the possibility of performing asimplified uncertainty analysis on a probabilistic safety assessment(PSA) of the Oskarshamn 3 nuclear power plant. The aim of the thesiswas divided in two parts, first to examine the uncertainty parametersof a PSA-model for Oskarshamn 3 and the second part was to developand examine a simplified method of uncertainty analysis as comparedto a more regular method of Monte Carlo-simulation. The thesis ismostly concerned with examining the core damage frequency. Theexamination of uncertainty parameters showed that many parameterswere missing from the model and thus further investigation areneeded, if a full Monte Carlo is to be performed. The simplifiedmethod for uncertainty analysis that was developed consisted ofassuming a lognormal distribution for the frequency of basic eventsand then using the minimal cutset-list to calculate an approximationto the end distribution. The simplified method was then compared tothe Monte Carlo-analysis for Oskarshamn 2 for different MCS-lists anda preliminary uncertainty analysis was performed for Oskarshamn 3.
39

ERP systémy pro terciární sektor ekonomiky - PSA / ERP Systems For the Tertiary Sector of Economy - PSA

Hájek, Martin January 2008 (has links)
The main goal of this thesis is to introduce philosophy of PSA (Professional Services Automation) solutions, their benefits, structure and possible future and to describe, why and how were PSA systems developed. Inasmuch as PSA systems originally evolved from ERP systems and their current progress is very similar to the late progress of ERPs, I decided to focus my analyses on ERP systems and to use the relevant conclusions on PSA solutions. The opening chapter of the thesis (chapter 3) introduces and describes philosophy and history of ERP systems, chapter 4 then describes PSA solutions. The fifth part is addressed to the current ERP market, from which a picture of future PSA market can be derived. Practical part 6, which I consider as the primary contribution of this thesis, analyzes some dimensions of PSA in the light of future evolution of this kind of solution. It also defines some factors, that may help to increase positive effects of PSA solutions to service-oriented companies. The thesis is then closed with an example of a real PSA implementation on an engineering company (chapter 7).
40

Das prostataspezifische Antigen (PSA) als Prädiktor des Prostatakarzinoms: Ein epidemiologischer Überblick der Versorgungsrealität in Deutschland von 2004 - 2014

Hiestermann, Constanze 10 March 2020 (has links)
Das Prostatakarzinom (PCa) ist der häufigste maligne Tumor des Urogenitaltraktes und stellt nicht nur in Deutschland die am häufigsten diagnostizierte Krebserkrankung des Mannes dar. Dem PSA wird im klinischen Alltag eine bedeutende Rolle für Diagnostik, Therapie und Verlauf der PCa-Erkrankung zugeschrieben, allerdings ist die größte Schwachstelle des PSA-Screenings die geringe Spezifität, welche häufig zu Überdiagnostik führt und letztendlich in Übertherapie endet. Ziel der vorliegenden Arbeit war es, die Versorgungsqualität und Versorgungsrealität von Patienten mit einem neu diagnostizierten PCa zu untersuchen und zu beurteilen. Hierfür wurde ein umfangreicher Datensatz von 38.560 Patienten untersucht, wobei das Hauptaugenmerk dabei auf der Häufigkeitsverteilung der PSA-Werte für PCa-Patienten verschiedener Alters- und Gleason-Gruppen lag, um daraus Aussagen über mögliche Grenzwerte ableiten zu können. Die Auswertung der Versorgungsdaten zeigte, dass in dem untersuchten Patientenkollektiv sowohl altersspezifische als auch gleasonspezifische PSA-Grenzwerte erkennbar sind. Der Grenzwert von 4 ng/ml zur Biopsieindikation scheint in der Praxis eine Orientie-rungshilfe zu sein, allerdings sollte dieser Wert auch differenziert bzgl. verschiedener Einflussfaktoren betrachtet werden und bedeutet anscheinend in der Versorgungsrealität nicht, dass sofort eine invasive Diagnostik bzw. Therapie durchgeführt wird. Vor allem in Hinblick auf die große Zahl an Überdiagnosen bzw. Übertherapien, die das PSA-Screening hervorrufen kann ist es wichtig, Strategien zu entwickeln, um Männer mit einem insignifikanten PCa vor möglichen Folgeschäden zu schützen. Bei einem im Vergleich zum Grenzwert erhöhten PSA-Wert sollte der Patient zunächst engmaschig überwacht werden bevor eine invasive Diagnostik durchgeführt wird. Konzepte der Spezifitätserhöhung wie PSA-Dichte, PSA-Anstiegsgeschwindigkeit und PSA-Verdopplungszeit konnten die Spezifität allerdings nur teilweise verbessern. Gleichzeitig zeigt die vorliegende Untersuchung, dass die Dokumentation des PSA bei der Früherkennung im Rahmen eines Versorgungsforschungsprojektes funktioniert, da die Daten sowohl wissenschaftlichen Erkenntnissen entsprechen, gleichwohl den Versorgungsalltag dokumentieren, der auch im Spannungsfeld der PSA-Diskussion zu sehen ist.

Page generated in 0.0173 seconds