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Squeeze film dampers are used in the high speed turbo machinery industry and aerospace industries as a means to reduce vibration amplitude, to provide damping, to improve dynamic stability of the rotor bearing system and to isolate structural components. The effects of cavitation included in previous studies were not effective. The effect of different design parameters were not studied thoroughly as experimental investigation of squeeze film dampers is very expensive. Few of them used numerical investigation but the methods they used are either time consuming or complicated. The present study investigated the feasibility of applying a steady state solver, which is computationally less expensive, for analyzing flow field inside the squeeze film dampers. The behavior of dynamic pressure profiles at different operating conditions, and the effect of a central groove on dynamic pressure profiles were also studied. Simulation results of a 3D case which is similar to the one experimentally studied by Delgado were used to establish if the moving reference frame (MRF) model in Fluent 12.1 can be used. A steady state solver in an absolute frame of reference was used to produce whirling motion of the rotor in this study. The inlet pressure of 31kpa and the whirling speed of 50 and 100Hz were used as boundary conditions. The mixture model with three percent dissolved air in lubricant is used to model multiphase flow. Singhal cavitation model is used to model cavitation. The simulations (50,000 iterations) were run until steady state solutions were reached. The results closely agreed with those obtained experimentally by San Andrés and Delgado. Numerical simulations of three-dimensional cases with an additional central groove on the squeeze film land were also performed to predict the effect of central groove on dynamic pressure profiles. Addition central groove reduces the pressures and forces generated by squeeze film damper.

Made available in DSpace on 2014-06-11T19:25:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-05-02Bitstream added on 2014-06-13T20:32:47Z : No. of bitstreams: 1 vergilio_sal_me_ilha.pdf: 3337665 bytes, checksum: 50e13409fecfd3249ea5cb1d7e6b9c79 (MD5) / Este trabalho trata da análise dos tipos de ligações usualmente empregadas em trelliças de cobertura constituídas por perfís de aço formados a frio. O escopo da análise engloba seu comportamento estrutural e modelos de cálculo. Além disso, apresenta e comenta os procedimentos indicados na norma brasileira NBR 14762:2010 Dimensionamento de estruturas de aço constituídas por perfís formado a frio (ABNT - ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS),pela NBR 8800:2008 Projeto de estruturas de aço e estruturas mistas de aço e concreto de edifícios - quando referidos pela primeira - e também por reconhecidas normas estrangeiras. Os meios de ligação estudados são parafusos e soldas; os elementos da ligação são as barras, cobrejuntas, chapas de gusset entre outros. As barras pertencentes às treliças são de perfís U ou L e suas combinações. Cada tipo de ligação de barra estudada apresenta as respectivas planilhas eletrônicas... / This work deals with the analysis of connections types commonly used in roof trusses consisting of steel cold-formed profiles. The scope of review includes its structural behavior and calculation models. it also presents and discusses the procedures specified by recognized foreign standards, the Brazilian Standard for cold-formed steel, and welded connections are studied; the connection elements are the bars, joint sheeting and gusset plates, among others... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:29:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-12Bitstream added on 2014-06-13T19:38:34Z : No. of bitstreams: 1 machado_ms_dr_botfmvz.pdf: 753288 bytes, checksum: 187c0d8cf0a2a6512626ff3476eafd08 (MD5) / Universidade Estadual Paulista (UNESP) / Respostas superovulatórias satisfatórias têm sido reportadas em éguas com o uso do Extrato de Pituitária Eqüina (EPE) e FSH purificado eqüino (eFSH), contudo as taxas de recuperação embrionária permanecem inconsistentes. O objetivo deste estudo foi avaliar as concentrações plasmáticas de estradiol, inibina, FSH e LH em éguas superovuladas com eFSH e EPE (em doses constantes ou decrescentes): antes, durante e imediatamente após o término da administração hormonal. Foram utilizadas seis éguas as quais foram submetidas aos seguintes tratamentos: Grupo I (GI) recebeu 25mg de EPE intramuscular (I.M.), Grupo II (GII) foram tratadas com EPE (I.M.) em doses decrescentes. No Grupo IIl (GIII), o EPE foi substituído por 12,5mg de eFSH (I.M.). O Grupo IV (GIV) foi utilizado como controle. Sangue foi coletado diariamente para avaliar as concentrações hormonais por radioimunoensaio. As coletas foram iniciadas dois dias antes da primeira aplicação medicamentosa, encerrando 48horas após a última ovulação do estro. As diferenças nos níveis plasmáticos hormonais foram comparadas utilizando-se o ANOVA, sendo considerada diferença estatística quando P0,05. O número médio de ovulações foi de 3,3; 4,8; 5,0 e 1,0 nos grupos 1 a 4, respectivamente, tendo sido maior (P<0,05) em todos os grupos superovulados em relação ao controle. As concentrações de estrógeno, inibina, FSH e LH não diferiram entre os grupos durante o período 1. No período 2, os valores de estradiol foram maiores (P<0,05) em éguas sob tratamento superovulatório com eFSH (GIII) 29,52pg/ml, os grupos I e II, apresentaram valores intermediários (GI: 16,75pg/ml, GII: 16,26pg/ml) e o GIV (7,78pg/ml) menor estatisticamente aos demais. Foi verificada uma correlação altamente positiva (R=0,615; P=0,01) entre os valores de estradiol e inibina, os quais, durante os tratamentos, foram maiores (P<0,05)... / Satisfactory superovulatory responses have been reported in mares with the use of equine pituitary extract (EPE) and purified equine FSH (eFSH), however embryo recovery rates are still inconsistent. Recent studies demonstrated that the superovulatory treatment disturbs oocyte maturation and transport. The main objective of the present study was to evaluate the plasmatic concentrations of estradiol, inhibin, FSH and LH in super ovulated mares treated with eFSH and EPE (with constant or decreasing doses): Six mares were used in a crossover experiment in four different groups: Group I mares received 25mg of EPE every twelve hours, Group II received EPE in decreasing doses and Group IlI mares received 12.5mg of eFSH (IM). Group IV served as control. Embryo flushes were performed 8 days pos ovulation. Blood was collected daily to evaluate hormonal concentrations through radioimuneassay, starting two days before the first administration, until 48 hours post-ovulation. Mean and daily hormonal concentrations of estradiol, inhibin, FSH and LH were evaluated. Hormonal concentrations were submitted to statistical analysis using ANOVA. Significance levels were set as P<0.05. Mean number of ovulations was 3.3; 4.8; 5.0 and 1.0 in groups 1 to 4, respectively, being higher (P<0.05) in all super ovulated groups, when compared to control. Concentrations of estrogen, inhibin, FSH and LH did not differ between groups during the first period. In period 2, estradiol levels were higher (P<0.05) in mares with superovulatory treatment eFSH (GIII) 29.52pg/ml, the groups GI and GII (GI: 16.75pg/ml, GII: 16.26pg/ml) values intermediary, and GIV (7.78pg/ml) levels lower. A positive correlation between estradiol levels and number of follicles ≥30mm (R=0.917; P<0.05), recovered embryos (R=0.945; P<0.05) and ovulations (R=0.75; P<0.05) was identified in super ovulated mares. A positive correlation (R=0.615; P=0.01) between estradiol and inhibin concentrations.

Orientador: Renato Bertolino Junior / Banca: José Antônio Matthiesen / Banca: João Alberto Venegas Requena / Resumo: Este trabalho trata da análise dos tipos de ligações usualmente empregadas em trelliças de cobertura constituídas por perfís de aço formados a frio. O escopo da análise engloba seu comportamento estrutural e modelos de cálculo. Além disso, apresenta e comenta os procedimentos indicados na norma brasileira NBR 14762:2010 "Dimensionamento de estruturas de aço constituídas por perfís formado a frio" (ABNT - ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS),pela NBR 8800:2008 "Projeto de estruturas de aço e estruturas mistas de aço e concreto de edifícios" - quando referidos pela primeira - e também por reconhecidas normas estrangeiras. Os meios de ligação estudados são parafusos e soldas; os elementos da ligação são as barras, cobrejuntas, chapas de gusset entre outros. As barras pertencentes às treliças são de perfís "U" ou "L" e suas combinações. Cada tipo de ligação de barra estudada apresenta as respectivas planilhas eletrônicas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work deals with the analysis of connections types commonly used in roof trusses consisting of steel cold-formed profiles. The scope of review includes its structural behavior and calculation models. it also presents and discusses the procedures specified by recognized foreign standards, the Brazilian Standard for cold-formed steel, and welded connections are studied; the connection elements are the bars, joint sheeting and gusset plates, among others... (Complete abstract click electronic access below) / Mestre

The accurate knowledge of the implantation profiles is of considerable interest for testing theoretical models on the stopping of ions in matter, as well as for many important applications in metallurgy and semiconductor technology. Measurements of the depth distribution profiles of the implanted ions provide information on a wide range of fields, including ion-solid interactions, doping and diffusion. Several experimental methods have been employed to determine the depth distributions of the implanted ions. They can be divided into destructive and non-destructive methods. Most experimental results found in the literature are for heavier ions implanted into lighter target materials where the non¬destructive Rutherford Back-scattering method can be employed. Nuclear Reaction Analysis also provides a non-destructive method for determining the implanted profile of impurity atoms with mass number smaller or similar to that of the target material. One of the important effects in ion implantation is sputtering, the process in which the surface of the target material is eroded due to ion bombardment. This process modifies range moments of implantation profiles for high fluences. This study is mainly concerned about effects of sputtering on the implanted depth profile as a function of fluence and target mass. Sputtering correction factors are determined numerically to correct the theoretical depth distributions. / Dissertation (MSc (Physics))--University of Pretoria, 2006. / Physics / unrestricted

The spectral separability of southern pines is a perplexing issue due to limited variance of spectral reflectance in species with similar morphological characteristics. Understory vegetation reflectance may exacerbate the ability to accurately identify various overstory tree species, specifically those of longleaf and loblolly pines in the southeastern US. In this study, identification of target level overstory crowns with varying degrees of understory vegetation cover based on fire return frequency was used to assess the role of understory reflectance on target crown species discernment. Seasonal variations of understory vegetation in late dormant and late growing seasons were compared for disparities in potential reflectance contribution from understory vegetation. Overall, the impact of understory vegetation was considered negligible in the spectral separability of longleaf and loblolly pines based on discriminant analysis results. Classification of WorldView-2 relative spectral profiles resulted in overall accuracies of 92% for dormant season and 96% for growing season imagery.

No description available.

<p> An experimental study of temperature profiles in the near vicinity of a horizontal copper surface on which water was boiled is reported in this thesis. A series of three tests is reported for heat fluxes of 20,000, 50,000 and 100,000 BTU/HRFT^2 respectively. Four levels of subcooling were achieved in each series in the range of 0°F < θsub < 105°F. Using the superheat-layer thickness. as defined by Han and Griffith, results are reported indicating an increase in superheatlayer thickness for an increase in the degree of subcooling at a constant heat flux and a reverse effect for an increase in heat flux for a constant degree of subcooling. </p> <p> In addition, five tests are reported in which incipience of boiling was achieved. Using this data, Hsu's mathematical model for predicting bubble nucleation is tested. In general, good agreement is found between the Hsu model and the experimental data. </p> / Thesis / Master of Engineering (MEngr)

No / An infrared temperature sensor has been used to provide real time quantification of the thermal homogeneity of polymer extrusion. The non-intrusive sensor was located in the barrel of a single screw extruder, positioned such that it provided a measurement of melt temperature in the channel of the metering section of the extruder screw. The rapid response of the technique enabled melt temperature within the extruder screw channel to be monitored in real time, allowing quantification of the thermal stability of the extrusion process. Two polyethylenes were used in experiments with three extruder screw geometries at a range of screw speeds. Data generated by the infrared sensor was found to be highly sensitive to thermal fluctuations relating to the melting performance of the extruder screw. Comparisons made with an intrusive thermocouple grid sensor located in the extruder die suggested that the infrared technique was able to provide a similar level of information without disturbing the process flow. This application on infrared thermometry could prove highly useful for industrial extrusion process monitoring and optimization.