Film cooling is a cooling technique widely used in high-performance gas turbines to protect turbine airfoils from being damaged by hot flue gases. Film injection holes are placed in the body of the airfoil to allow coolant to pass from the internal cavity to the external surface. The ejection of coolant gas results in a layer or “film” of coolant gas flowing along the external surface of the airfoil. In this study, a new cooling scheme, mist/air film cooling is proposed and investigated through experiments. Small amount of tiny water droplets with an average diameter about 7 μm (mist) is injected into the cooling air to enhance the cooling performance. A wind tunnel system and test facilities were build. A Phase Doppler Particle Analyzer (PDPA) system is employed to measure droplet size, velocity and turbulence. Infrared camera and thermocouples are both used for temperature measurements. Mist film cooling performance is evaluated and compared against air-only film cooling in terms of adiabatic film cooling effectiveness and film coverage. Experimental results show that for blowing ratio M=0.6, net enhancement in adiabatic cooling effectiveness can reach 190% locally and 128% overall along the centerline. The general pattern of adiabatic cooling effectiveness distribution of the mist case is similar to that of the air-only case with the peak at about the same location. The concept of Film Decay Length (FDL) is proposed to quantitatively evaluate how well the coolant film covers the blade surface. Application of mist in the M=0.6 condition is apparently superior to the M=1.0 and 1.4 cases due to the higher overall cooling enhancement, the much longer FDL, and wider and longer film cooling coverage area. Based on droplet measurements through PDPA, a profile describing how the airmist coolant jet flow spreads and eventually blends into the hot main flow is proposed. A sketch based on the proposed profile is provided. This profile is found to be well supported by the measurement results of Turbulent Reynolds Stress. The location where a higher magnitude of Turbulent Reynolds Stress exists, which indicates higher strength of turbulent mixing effect, is found to be in the close neighborhood of the edge of the coolant film envelope. Also the separation between the mist droplets layer and the coolant air film is identified through the measurements. In other words, large droplets penetrate through the air coolant film layer and travel further over into the main flow. Based on the proposed air-mist film profile, the heat transfer results are reexamined. It is found that the location of optimum cooling effect is coincident with the starting point where the air-mist coolant starts to bend towards the surface. Thus the data suggests that the “bending back” film pattern is critical in keeping the mist droplets close to the surface which improves the cooling effectiveness for mist cooling.

In the modern advanced gas turbines, the turbine inlet temperature may exceed 1500°C as a requirement to increase power output and thermal efficiency. Therefore, it is imperative that the blades and vanes are cooled so they can withstand these extreme temperatures. Film cooling is a cooling technique widely used in high-performance gas turbines. However, the film cooling effectiveness has almost reached plateau, resulting in a bottleneck for continuous improvement of gas turbines' efficiency. In this study, an innovative cooling scheme, mist film cooling is investigated through experiments. A small amount of tiny water droplets with an average diameter about 10-15 µm (mist) is injected into the cooling air to enhance the cooling performance. A Phase Doppler Particle Analyzer (PDPA) system is used for droplet measurements. Mist film cooling performance is evaluated and compared against air-only film cooling. This study continues the previous work by (a) adding fan-shaped holes and comparing their cooling performance with the round holes, (b) extending the length of the test section to study the performance farther downstream the injection holds, and (c) using computational simulation to investigate the feasibility of transporting mist to the film cooling holes through gas turbine inside passages. The results show that, with an appropriate blowing ratio, the fan-shaped holes performs about 200% better than round holes in cooling effectiveness and adding 10% (wt.) mist can further enhance cooling effectiveness 170% in average. Farther downstream away from the injection holes (X/D> 50), mist cooling enhancement prevails and actually increases significantly. PDPA measurements have shed lights to the fundamental physics of droplet dynamics and their interactions with thermo-flow fields. These experimental results lead to either using lower amount of cooling air or use fewer number of cooing holes rows. This means higher gas turbine power output, higher thermal efficiency, and longer components life which will reflect as a cheaper electricity bill. Computational Fluid Dynamics (CFD) showed that it is feasible to transport the water mist, with initial diameters ranging from 30 µm-50 µm and mist ratio of 10-15%, to the cooling holes on the surface of the turbine vanes and rotors to provide the desired film cooling. Key words: Gas Turbines, Heat Transfer, Film / mist Cooling, Experimental Study, Mist Transport, CFD, PDPA.

Submitted by Verena Bastos (verena@uefs.br) on 2015-10-16T12:16:16Z No. of bitstreams: 1 DISSERTA??O TATIANE ALMEIDA FERREIRA _1_.pdf: 2933902 bytes, checksum: 40a3f4e9011ca770886df2ef7efb28e3 (MD5) / Made available in DSpace on 2015-10-16T12:16:16Z (GMT). No. of bitstreams: 1 DISSERTA??O TATIANE ALMEIDA FERREIRA _1_.pdf: 2933902 bytes, checksum: 40a3f4e9011ca770886df2ef7efb28e3 (MD5) Previous issue date: 2013-08-23 / This work aims at analyzing the dialogic relationship between literature and its illustration in order to show the creation of imaginary formed on the black ? mixed people, the traditions, the mystique surrounding the "City of Bahia " with its syncretism religious, faith and popular festivals. This discursive intersection gives rise to other forms of reading, interpreting, serving for the understanding of the unique aspects about the varied universe mythical- religious and cultural place. We take as an example the illustrated edition of Bahia de Todos os Santos: street guides and mysteries, Jorge Amado, 1977 edition, featuring the designs of Carlos Bastos. The approach is interdisciplinary because the intent of the writer was to build an artistic, historical- cultural and human panel of Bahian metropolis, so many sources of knowledge, artistic forms were used in order to understand an imaginary, gestated in reality and invention. The city is widely known as the writer proposes to show it to an imaginary tourist, that it may come to know it in its concreteness. For these reasons, the text seems to set up a tour guide, however its operatic quality, interspersed with the mystery, let?s find its fictional quality. Moreover, the work is a cultural-historical testimony, to discuss issues of the past and who are pressing for the decade in which the guide has been updated since the city of Salvador urbanized throughout the twentieth century and grew up with her problems social and economic character. / Este trabalho tem como proposta analisar a rela??o dial?gica entre a literatura e sua ilustra??o, a fim de evidenciar a cria??o do imagin?rio formado acerca do povo negro-mesti?o, das tradi??es, da m?stica que envolve a ?Cidade da Bahia?, com o seu sincretismo religioso, f? e festas populares. Esse cruzamento discursivo d? origem a outras formas de leitura, interpreta??o, servindo para o entendimento de aspectos singulares acerca do variado universo m?tico-religioso e cultural do lugar. Tomamos como exemplo a edi??o ilustrada de Bahia de Todos os Santos: guia de ruas e mist?rios, de Jorge Amado, edi??o de 1977, que conta com os desenhos de Carlos Bastos. A abordagem ? interdisciplinar porque a inten??o do escritor era construir um painel art?stico, hist?rico-cultural e humano da urbe baiana, por isso foram utilizadas diversas fontes de conhecimento, de linguagens art?sticas, a fim de compreender um imagin?rio, gestado na realidade e na inven??o. A cidade ? amplamente divulgada quando o escritor se prop?e a mostr?-la para uma turista imagin?ria, para que ela venha a conhec?-la em sua concretude. Por tais aspectos, o texto parece configurar um guia tur?stico, contudo, a sua caracter?stica l?rica, entremeada ao mist?rio, permite constatar a sua qualidade ficcional. Al?m disso, a obra ? um testemunho hist?rico-cultural, por discutir quest?es do passado e das que s?o prementes para a d?cada em que o guia foi atualizado, visto que a cidade do Salvador se urbanizou ao longo do s?culo XX e com ela cresceram problemas de car?ter social e econ?mico.

Cystic fibrosis (CF) is one of the most common fatal inherited diseases, most prevalent among Caucasians. CF is caused by a mutation in the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR), which helps to create sweat, digestive juices, and airway surface liquid (ASL). The airways are covered with a thin layer of fluid, the airway surface liquid, in which the cilia bathe. Defective or absent CFTR leads to a defective water and ion transport in the epithelial cells, which results in viscous mucus, defective ciliary clearance, bacterial inflammation and tissue damage. The volume and composition of ASL are important in the pathogenesis of cystic fibrosis and it is therefore relevant to determine its composition. However, there are a number of difficulties in determining the ionic composition of the ASL due to its small volume. Literature data vary from very hypotonic to markedly hypertonic. These controversial data inspired the development of a simple method for determining the elemental composition of the ASL in different animal species and humans. Two techniques were developed to determine the composition of ASL, from which indirect information on chloride transport in airway epithelium can be obtained. In the first method, tissue is removed from the animals under anesthesia, frozen and analyzed in the frozen-hydrated state. In the second method, the ASL is collected with small dextran (Sephadex) beads; the dried beads are then analyzed by X-ray microanalysis. The Sephadex-bead method appears more accurate compared to the frozen-hydrated samples. Both methods were applied to collect tracheal and/or nasal fluid in pigs, normal and transgenic cystic fibrosis mice, the fluid covering the apical surface of normal bronchial cells (16HBE14o-) and a cystic fibrosis human bronchial cell line (CFBE41o-), and finally nasal fluid in healthy and diseased subjects. The ionic composition of the ASL was isotonic both in pigs and healthy human subjects. CF patients had much higher levels of Na and Cl ions than healthy subjects. The ASL under control conditions was hypotonic in mice and cell cultures, whereas the concentrations of Na and Cl ions in the species with the ΔF508 mutation or absent CFTR were significantly higher than in the corresponding controls. It was also demonstrated that the ionic composition of the ASL can be influenced by pharmacological treatment. The study confirms earlier findings that CFTR also is involved in bicarbonate transport. Mist tent therapy has been tested in the study of a treatment for CF patients, in order to hydrate the viscous mucus. But the effect of mist tent therapy on ion concentrations in the ASL appeared to be short-lived, although no patients became chronically colonized with pseudomonads while on nocturnal mist tent therapy.

An online, semi-continuous instrument to measure both total and gas phase atmospheric reactive oxygen species (ROS) and determine the concentration of ROS in the particle phase (ROS(p)) was developed. This instrument was based on a fluorescent probe for quantifying ambient ROS, specifically 2'7'-dichlorodihydrofluorescin, or DCFH probe. This probe was analyzed for sensitivity to a variety of offline and online parameters for efficient use in a field instrument. The ROS(p) instrument measures the peak light intensity at 530 nm to determine ambient ROS concentrations. ROS particles and gases are collected in a mist chamber in a nebulized mist. The instrument alternates measurements of ROS(p+g), or ROS(tot) by means of an inline filter. Fine (PM₂.₅) (ROS(p) is determined by subtraction of the ROS(g) concentration from the ROS(tot), as the ROS(g) signal could not be excluded. This instrument was tested during the summer (May-July) of 2012 at urban and rural sites in the metropolitan Atlanta and surrounding region. Concentrations of ROS(p) determined from this instrument were often below limit of detection. Average concentrations of ROS(p) were found to be 0.25 nmol/m³ in urban Atlanta (Jefferson St. and Georgia Tech), and 0.15 nmol/m³ in Yorkville, a rural site. A side by side comparison of this method with a filter collection method was made in July. The average ROS(p) offline concentrations were 0.15 nmol/m³. These concentrations were comparable to the online average concentrations of 0.21 nmol/m³ for the same period of time. This average and the majority of the measurements comprising it is dominated by the high limit of detection. The ROS instrument as constructed and operated is an efficient way to conduct ROS(p) measurements at the level of a filter study while reducing the labor intensive filter collection and extraction. In order for this instrument to be successful at measuring ambient ROS in the particle phase, the removal of the gas phase from the current sampling scheme is critical as the ROS(g) concentrations are over 90% of the measured ROS. The system as currently operable is best suited for source measurements, including biomass burning plumes or fresh exhaust to capture immediate formation.

The purpose of this study is to examine a completely new phenomenon called the MIST, by two portfolios: the Goldman Sachs Next 11 equity fund, and the Goldman Sachs BRIC fund, in order to establish whether or not the MIST countries are a better investment decision in terms of risk, return and growth. Furthermore, the study examines in which form these emerging markets lies in terms of market efficiency, and if the random walk theory is present. The opportunities and challenges for Mexico, Indonesia, South Korea and Turkey are also brought upon to determine whether these countries have the potential to exhibit the same success as the BRIC countries did for a decade. Since the growth of the BRIC countries are slowing down, Jim O’Neill, the same founder of the term BRIC, coined the nations MIST. The BRIC countries are facing several difficulties and have led investors to draw out from these countries stocks. Investors that were pouring in money to the BRIC countries during the period 2001-2009, have from 2011, withdrawn 15 billion dollars from the BRIC stocks. Mexico, Indonesia, South Korea and Turkey. Derived from the next eleven countries, these countries have a major effect on the global economy due to their economical and political circumstances. For many investors, the MIST countries that are growing faster than the BRIC are regarded to be the new biggest emerging markets. Investing in BRIC funds are stated to be a disaster today, while on the other hand, the MIST countries are growing and outpacing the BRIC fund. The methodology used was to compare two different portfolios, Goldman Sachs N-11 equity fund in the period 2011-2013 against the Goldman Sachs BRIC fund in two different periods, 2011-2013 and 2006-2008 with S&P 500 as the market index. In addition, a hypothesis test was carried out for this period to observe whether or not to reject the null hypothesis. The results of this study shows that the null hypothesis was rejected and that the N-11 equity fund is a better investment decision, in terms of risk, return and growth today. These emerging markets are under the weak form market efficiency and the random walk theory is present in the N-11 equity fund. This makes the authors’ results more of a speculation than a definite conclusion about the future, as one cannot "beat the market".

Made available in DSpace on 2015-04-17T14:55:31Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2030208 bytes, checksum: a9ca9fd74d6c51300138eb942585c8c8 (MD5) Previous issue date: 2013-04-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Ecological analysis of the structure of understory bird communities of forest remnants of Atlantic Forest of Paraíba. South America is the region with the highest bird diversity in the world. The Atlantic Forest biome in Brazil is the second most diverse. Its portion in Paraíba integrates Pernambuco Endemism Centre, a region that is home of two-thirds of the bird species present in the biome. The present study investigated the bird communities in the understory of three Atlantic Forest remnants of Paraíba through the method of capture with mist nets. Ten nets were positioned in the forest understory in eight different points in each remnant, in a summit of 48 day samples, in a total effort of 2.895 hours-net. A total of 333 specimens of 44 species were captured, divided into 19 families. The recapture rate was 2%. The species with the highest representation were Arremon taciturnus (n = 40), Chiroxiphia pareola (n = 32) and Conopophaga melanops (n = 28), the latter being an endemic species considered as threatened in the Atlantic Forest with the status of vulnerable . Endangered species totaled 16% of the records and the same value was found for the endemic. Species richness among the three remnants did not differ (χ² = 0.667, d.f = 2, p = 0.7165), and according to the communities of birds found, diversity was considered low, with a predominance of dominant and generalists species. The species composition was little similar among the remnants, suggesting that the size, matrix and the availability of different microhabitats in each remnant may have influenced the species presence. The Reserva Particular do Patrimônio Natural Engenho Gargaú remnant was the one with the highest number of endemic and threatened species, as well as with the most understory insectivores, thus suggesting that this remnant is best conserved. / Análise ecológica da estrutura das comunidades de aves de sub-bosque de remanescentes florestais de Mata Atlântica da Paraíba. A América do Sul é a região que possui a maior diversidade de aves no mundo. No Brasil a Mata Atlântica é o segundo bioma mais diverso. A Mata Atlântica da Paraíba integra o Centro de Endemismo Pernambuco, uma região que abriga cerca de 2/3 de das espécies de aves presentes no bioma. O presente estudo investigou as comunidades de aves de sub-bosque de três remanescentes de Mata Atlântica da Paraíba através do método de captura com redes de neblina. Dez redes foram posicionadas no sub-bosque florestal em oito pontos distintos ao longo de cada remanescente, tendo sido realizadas 48 dias de amostragem ao todo, totalizando 2.895 horas-rede. Ao todo foram capturados 333 indivíduos de 44 espécies divididas em 19 famílias. A taxa de recaptura foi de 2%. As espécies com maior representatividade foram Arremon taciturnus (n = 40), Chiroxiphia pareola (n = 32) e Conopophaga melanops (n = 28), sendo esta última espécie endêmica e ameaçada da Mata Atlântica com status de vulnerável . As espécies ameaçadas totalizaram 16% dos registros e o mesmo valor foi encontrado para as espécies endêmicas. A riqueza de espécies entre os três remanescentes não diferiu (χ² =0,667; g.l = 2; p = 0,7165), e de acordo com as comunidades de aves encontradas, a diversidade foi considerada baixa, com predominância de espécies dominantes e generalistas. A composição das espécies foi pouco similar entre os remanescentes, sugerindo que o tamanho, a matriz e a disponibilidade de microhabitats distintos de cada um possam ter influenciado na presença das espécies. O remanescente Reserva Particular do Patrimônio Natural Engenho Gargaú foi o que apresentou o maior número de espécies endêmicas e ameaçadas, assim como insetívoros de sub-bosque, sugerindo assim que tal remanescente seja mais bem conservado.

L'application de la brumisation d'eau dans l'air en amont des condenseurs à air permet de réduire la consommation d'énergie des machines frigorifiques. L'intérêt de la brumisation d'eau réside dans l'abaissement de température de l'air obtenu par évaporation du spray. L'optimisation de cette méthode permet d'obtenir une efficacité se rapprochant de celle des systèmes évaporatifs tout en supprimant le risque de développement et de transports de bactéries tel que les légionelles. Le problème est abordé ici de deux manières : la première théorique et numérique (utilisation du code MIRABELLES et développement d'un modèle d'échange thermique air-goutte/condenseur) et la seconde expérimentale (mise en place d'un pilote et d'une pompe à chaleur). A l'aide du code MIRABELLES, on a déterminé les caractéristiques d'un spray évoluant dans un milieu ambiant donné et son impact sur l'abaissement de température de l'air. Les données numériques obtenues ont guidé le choix du matériel et la stratégie de brumisation à appliquer expérimentalement. Les mesures effectuées sur le pilote montrent l'amélioration des échanges thermiques entre l'air et le condenseur grâce à la brumisation et quantifient également l'influence de l'impact des gouttes avec les ailettes du condenseur. L'application de la brumisation sur la pompe à chaleur a mis en avant les gains sur la consommation électrique et l'augmentation de la production frigorifique. La comparaison de l'ensemble des résultats expérimentaux avec les résultats numériques a permis de valider le modèle thermique simulant les échanges entre un air chargé de gouttelette d'eau et un condenseur. / The application of water mist in the air upstream of the air-cooled condensers can reduce the energy consumption of refrigeration. The advantage of water mist is the lowering of air temperature obtained by evaporation of the spray. The optimization of this method provides an efficiency approaching that of evaporative systems while eliminating the risk of development and transport of bacteria such as legionella. The problem is addressed here in two ways: the first theoretical and numerical (using the code MIRABELLES and development of a model heat exchange air-droplet/condenser) and the second experiment (establishment of a pilot and a heat pump). Using the code MIRABELLES, it was determined the characteristics of a spray operating in a given environment and its impact on the lowering of air temperature. The digital data obtained have guided the choice of materials and the experimental using condition of water mist. Measurements on the pilot show the improvement of heat exchange between air and the condenser by means of the mist and quantify the influence of the impact drops/condenser fins. The application of the mist on the heat pump has highlighted the gains in power consumption and the increase in refrigeration. The comparison of all experimental results with the numerical results has validated the thermal model simulating the interaction between a droplet-laden air and water condenser.

Continuous casting is an important process to transform molten metal into solid. Arrays of spray nozzles are used along the process to remove heat from the slab letting it solidify. Efficient and uniform heat removal without slab cracking is desired during steel continuous casting, and air-mist sprays could help to achieve this goal.Air-mist nozzles are one of the important keys for determining the quality of steel as well as energy consumption for pumping the water. Based on industrial data, it is estimated that a 1% reduction in scrapped production due to casting related defects can result in annual savings of 40.53 million dollars in the U.S. Computational simulations studies can minimize defects in steel such as cracks, inclusions, macro-segregations, porosity, and others, which are closely related to the heat transfer between water droplets and hot slab surface.<div><br></div><div>Conducting multiple spray experiments in order to find optimum operating conditions might be impractical and expensive in some cases. Thus, Computational Fluid Dynamics (CFD) simulation is aimed to be used for simulating the air-mist spray process. Because it is a challenging process due to strong air and water interaction, then numerical models have been developed to simulate water droplets. The first model involves air and water phases which then are transformed in single-phase water droplets. To do so, a Volume of Fraction (VOF) to the Discrete Phase Model (DPM) is used.<br></div><div><br></div><div>VOF-TO-DPM transition model involves the primary and secondary breakup which occurs in the water atomization process, starting with a single water core, followed by a smaller compact mass of water known as lumps or ligaments due to the interaction of air, and finally converted into water droplets.The second model is using the Nukiyama-Tanasawa function size distribution which injects water droplets based on defined size range and velocity profile. A validation of droplet size and velocity against experimental data has been accomplished. The models can avoid acquiring expensive equipment in order to understand nozzle spray performance, and droplets generated. Quality, water droplet velocity, size, energy, and water consumption are the core of the current study. Last but not least, the methodology for this model can be used in any other air-mist nozzle design.<br></div>

The harsh radiation environment of space is known to cause bit flips in computer memory. The conventional way to combat this is through error detection and correction (EDAC) circuitry, but for low-budget space missions software EDAC can be used. One such mission is the KTH project Miniature Student Satellite (MIST), which aims to send a 3U CubeSat into low-Earth orbit. To ensure a high level of data reliability on board MIST, this thesis investigates the performance of different types of EDAC algorithms. First, a prediction of the bit flip susceptibility of DRAM memory in the planned trajectory is made. After that, data reliability models of Hamming and Reed-Solomon (RS) codes are proposed, and their respective running times on the MIST onboard computer are approximated. Finally, the performance of the different codes is discussed with regards to data reliability, memory overhead, and CPU usage. The findings of this thesis suggest that using an EDAC algorithm would greatly increase the data reliability. Among the codes investigated, three good candidates are RS(28,24), RS(196,192) and RS(255,251), depending on how much memory overhead can be accepted. / Rymdens strålningsmiljö är känd för att orsaka bitflippar i datorminnen.Vanligtvis motverkas detta genom att felrättande hårdvara installeraspå satelliten, men för lågkostnadssatelliter kan rättningen iställetskötas i mjukvaran. Ett exempel på en sådan satellit är KTH-projektetMiniature Student Satellite (MIST), vars mål är att skicka upp en 3UCubeSat i låg omloppsbana. Den här uppsatsen undersöker hur olika felrättningsalgoritmer kananvändas för att skydda data ombord på satelliten från att bli korrupt. Först görs en uppskattning av hur strålningskänsliga DRAM minnenär i den planerade omloppsbanan. Därefter föreslås datakorruptionsmodellerför Hamming- och Reed-Solomonkoder (RS) tillsammans meden uppskattning av deras respektive körtider på satellitens omborddator. Slutligen diskuteras de föreslagna koderna med hänsyn till datakorruptionsskydd,minnesanvändning och processoranvändning. Uppsatsens slutsats indikerar att användandet av felrättningsalgoritmerkraftigt minskar risken för datakorruption. Bland de kodersom undersökts framstår RS(28,24), RS(196,192) och RS(255,251) somde bästa alternativen, beroende på hur mycket extra minnesanvändningsom är acceptabelt.