Дисертації з теми "Dose coefficients"
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Finklea, Lauren. "Room radiation dose coefficients for external exposure." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53943.
Повний текст джерелаLarsson, Ylva. "Establishing low-energy x-ray fields and determining operational dose equivalent conversion coefficients." Thesis, Stockholm University, Medical Radiation Physics (together with KI), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8319.
Повний текст джерелаReference radiation fields for x-ray qualities are described by the International Organization of Standards (ISO). This study describes the procedure to establish nine different low energy X-ray qualities at the national metrology laboratory, Swedish Radiation Protection Authority, following the document ISO 4037. Measurements of tube voltage, half-value layer, mean energy and spectral resolution have been performed for qualities N-15, N-20, N-25, N-30, N-40, L-20, L-30, L-35 and L-55. Furthermore, dose equivalent conversion coefficients for operational quantities ambient dose equivalent, personal dose equivalent and directional dose equivalent have been calculated by folding the mono-energetic conversion factors with measured spectral distributions of the x-ray qualities. The spectral distributions were unfolded from pulse-height distributions to photon distributions using simulated data of the semi-conductor detector used for measurements, generated with the Monte Carlo code PENELOPE.
Nielsen, Adam Derek. "Monte Carlo calculation of fluence-to-ambient dose equivalent conversion coefficients for high-energy neutrons." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/16424.
Повний текст джерелаSantos, Josilene Cerqueira. "Determinação experimental da distribuição de dose absorvida em diferentes qualidades de feixes mamográficos." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-26042018-121103/.
Повний текст джерелаThe mean glandular dose is the quantity used for dosimetry in mammography. This quantity has a strong dependence with some properties of the evaluated breast, such as its glandularity and compressed thickness. It also depends on the X-ray spectrum used for the mammographic image production, such as the target/filter combination and the tube voltage, which are related to the half value layer (HVL) of the beam. The X-ray beam characterization by means of the direct measurement of its spectrum is a complex procedure, and it is difficult to be implemented in clinical systems due to the architecture of the mammography equipment and the high photon fluence rates. These spectra provide a complete qualitative and quantitative information of the X-ray beam. The general objective of this work is to estimate mean glandular dose distributions in different depths of breast tissue-equivalent materials (bTEM) considering the X-ray spectra measured in clinical mammography devices. Radiographic techniques commonly applied for breast cancer screening were used. The behavior of the mean glandular dose normalized to the incident air kerma (DgNp), with parameters related to the breast (glandularity and compressed thickness) and to the mammographic spectra (HVL, tube voltage, target/filter combination), was evaluated. First, an experimental methodology was developed to measure X-ray spectra in clinical mammography devices. Then, the following methods for calculating the DgNp using these spectra were considered: Method I, which calculates the DgNp using the incident spectra; Method II, which uses incident and transmitted spectra by the bTEMs, and Method III, which uses incident and transmitted spectra to estimate the dose distributions in depth of the breast equivalent materials. Finally, thermoluminescent dosimeters (TLDs) were used as a comparative method to evaluate DgNp distributions. The methodology developed for measuring spectra proved to be efficient for the proper positioning and alignment of the detector and, consequently, for the measurement of direct X-ray spectra. The experimental incident spectra showed good agreement with spectra simulated in similar conditions. The results showed well-defined trends (either linear or exponential) of the distributions of these coefficients (DgNp) regarding the analyzed parameters. The DgNp values presented an exponential decay with the bTEM thickness and linear decrease with the glandularity. In addition, these coefficients increase linearly with the increase of the HVL and, consequently, with the increase of the effective energy. From the distributions of DgNp (obtained by Method III) it was possible to estimate the DgNp in the whole breast with a maximum difference of 5.2% from the values obtained using the Method II. The variation of the DgNp with the depth, obtained with TLDs, showed to be consistent with the results observed using the Method III. In conclusion, it is possible to evaluate the glandular dose in mammography examinations using X-ray spectra and the suggested methodology, with some adaptations, can be applied as an alternative procedure for dosimetry in mammography.
Nordqvist, Malin. "Modellering av byggnaders skyddskoefficienter vid utsläpp av radioaktiva ämnen." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-195665.
Повний текст джерелаIn case of a radioactive release, it is important to have good preparedness with the right actions to contribute the best protection for the vulnerable section of the population. Immediately after a release theexposure through inhalation will be the biggest problem, since particles and gases have not beendeposited on land, clouds and so on. Buildings contribute to protection against inhalation. The reason forthis is that the air outside and inside the dwelling is changed relatively slowly. How much of the pollutionthat enter the indoor air and how long time it takes is important information to determine if thepopulation is sufficiently protected inside buildings or if evacuation is needed. In this work knowledgefrom existing literature and modelling has been used to describe general conditions with which apollutant moves in and out of a building. Differential equations with main processes and parameters havebeen studied to give a estimation as to the protection a building can provide against exposure throughinhalation of particles and gases in a radioactive cloud. Different types of ventilation systems, with orwithout associated particle filter are discussed and inhalation dose for different age groups and activitylevels are examined.A buildings protection coefficient is defined by comparing the amount of pollution in the air outside withthe air inside a building. The three main processes that control the transport of the pollution in and outfrom a building are ventilation, penetration and deposition. Ventilation arises of air exchange betweenindoor and outdoor air. Ventilation is controlled either mechanically or naturally. Penetration describesthe proportion of the particles or gases that enter trough the buildings shell. Deposition of particles andgases accurse due to the fact that they tend to stick to the surfaces they pass in transit. The deposition alsooccurs on all surfaces inside the building. After the particles and gases have become deposited, they mayre‐suspend and come back up into the air permitting inhalation before they once more deposit onavailable surfaces. The deposit is seen as a sink while re‐suspension acts as a source for indoor airconcentration.One of the factors that have a large impact of a buildings protection factor is the particle diameter, due tothe deposition and penetration process strongly dependent on particles size. Large and small particlesdeposited easier and the remaining fraction, the midfraction (0.2 to 1 micron in diameter), remains. Thisfraction will stay in the air longer since the deposition process does not affect it strongly. Gases moveeasily in and out of the building and are not prevented by the particle filter. However, there are specialfilters to install that prevent gases to penetrate, such as carbon filters. The rate of decay of the variousradionuclides also affects the protection factor. When nuclides decay the concentration in the airdecreases, the decay is then a sink of the concentration indoors. Ventilation rate has a certain influence onprotection coefficient. An increased ventilation rate leads to the concentration inside approaching thepenetration factor; this is applied if the ventilation rate can be assumed to be much higher than thedeposit rate. Ventilation system equipped with a particle filter can keep a large part of the pollutantoutside the building. Particle filters have different efficiency and are classified as coarse, medium and finefilter. High filter efficiency has a major impact on the protection coefficient. For a filter to functionproperly it demands maintenance and should be replaced in time.Inhalation dose depends on the particle size, since the deposition process affected in respiratory functionis similar to the transport in and out of a building. The midfraction tends to penetrate deep into the lungsafter inhalation. The effect of inhalation is due to an individual's age, size, and physical activity.
Cavalcante, Fernanda Rocha. "Simulação Monte Carlo de cenários de radiologia intervencionista pediátrica no código MCNPX." Universidade Federal de Sergipe, 2017. https://ri.ufs.br/handle/riufs/5271.
Повний текст джерелаInterventional radiology consists of minimally invasive procedures guided by real-time X-ray imaging of a region of the patient to be diagnosed or treated. Since it is a practice that uses ionizing radiation, performing these procedures should follow the three basic principles of radioprotection, which are justification, optimization (medical exposure), and dose limitation (occupational exposure). Interventional procedures in children with congenital heart defects are justified by substituting other high-risk procedures. However, as these procedures are responsible for high doses in the patient and individuals occupationally exposed (IOE), it is important to evaluate the medical exposures of pediatric individuals due to a greater susceptibility to radiation damage in these individuals who present a rapid metabolism and closer proximity of the organs. In addition, the longer life expectancy in children allows more time for any harmful effects of radiation, such as cancer, to manifest. Because direct dose measurement within the human body is difficult or impractical, the Monte Carlo simulation of radiation transport is a useful tool in estimating dosimetric protection quantities (H T and E) in anthropomorphic phantoms representing the anatomy of the human body. In addition, it is possible to calculate conversion coefficients that relate protection quantities with measurable quantities, such as the kerma-area product (PKA). In this work, we modelled paediatric interventional cardiology scenarios using the MCNPX code and a pair of adult and paediatric hybrid anthropomorphic phantoms (newborn, 1 year and 5 year) to evaluate medical and occupational exposures. The results obtained in this work show conversion coefficients H T /PKA and E/PKA of 5 to 16 times higher than the values obtained in the literature for interventional procedures performed in adult patients. In addition, we estimate the influence of personal protective equipment (lead apron, thyroid shield and lead glasses) on occupational exposures, which contribute to reduction of H T doses in the physician up to 98% (gonads and thyroid), when used.
A radiologia intervencionista consiste de procedimentos minimamente invasivos guiados por imagens de raios X em tempo real de uma região do paciente a ser diagnosticada ou tratada. Por ser uma prática que utiliza radiação ionizante, a realização destes procedimentos deve seguir os três princípios básicos de radioproteção, que são a justificação, otimização (exposição do paciente) e limitação de dose (exposição do médico). Os procedimentos intervencionistas em crianças com cardiopatias congênitas são justificáveis por substituírem outros procedimentos de alto risco. Entretanto, conforme estes procedimentos são responsáveis por altas doses no paciente, além dos indivíduos ocupacionalmente expostos (IOE), é importante avaliar as exposições médicas de indivíduos pediátricos devido uma maior susceptibilidade de ocorrência de danos provocados pela radiação nestes indivíduos, que apresentam metabolismo rápido e maior proximidade anatômica dos órgãos. Além disso, a maior expectativa de vida das crianças induz uma maior probabilidade de ocorrência de efeitos estocásticos tardios como o câncer. Devido à medição direta da dose dentro do corpo humano ser difícil ou impraticável, a simulação Monte Carlo do transporte de radiação é uma ferramenta útil na estimativa de grandezas dosimétricas de proteção (H T e E) em simuladores antropomórficos que representam a anatomia do corpo humano. Além disso, é possível calcular coeficientes de conversão que relacionam grandezas de proteção com grandezas mensuráveis, como o produto kerma-área (PKA). Neste trabalho, modelamos cenários de cardiologia intervencionista pediátrica utilizando o código MCNPX e uma dupla de simuladores antropomórficos híbridos adulto e pediátrico (recém-nascido, de 1 e 5 anos) para avaliar as exposições médicas e ocupacionais. Os resultados obtidos neste trabalho mostram coeficientes de conversão H T /PKA e E/PKA de 5 a 16 vezes maiores que os valores obtidos na literatura para procedimentos intervencionistas realizados em pacientes adultos. Além disso, estimamos a influência dos equipamentos de proteção individual (avental, óculos plumbíferos e protetor de tireoide) nas exposições ocupacionais, que contribuem para redução das doses H T no médico em até 98% (gônadas e tireoide), quando utilizados.
Hernandes, Fabiano. "Unsteady aerodynamic coefficients obtained by a compressible vortex lattice method." Instituto Tecnológico de Aeronáutica, 2009. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=954.
Повний текст джерелаTomal, Alessandra. "Medidas experimentais dos coeficientes de atenuação de tecidos mamários e sua influência no contraste e dose mamográfica." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-12092007-082142/.
Повний текст джерелаThe study and determination of attenuation properties of breast tissues are fundamental to understand and quantify contrast and absorbed dose in the mammographic examination. The purpose of this work is to experimentally determine the attenuation coefficient of breast tissues, and then to include these results into a theoretical analytical model, in order to study the influence of several parameters on subject contrast and dose in mammography. Among the parameters studied, one can emphasize the breast characteristics (geometry and composition), the radiographic technique, the target-filter combination and the image receptor. The attenuation coefficients were measured using narrow beam geometry, within the energy range of 8-30 keV, using an x-ray diffractometer 4-circle P3 Nicolet-Siemens and a monocromator of Si (111). For these measurements were analyzed 63 breast tissue samples (previously classified as normal tissues, fibroadenomas and several types of carcinomas). The linear attenuation coefficients measured were compared with theoretical predictions obtained from the mixture rule, and with experimental data previously published. The developed model to the subject contrast takes into account the primary and scattered contribution of the transmitted radiation. The average absorbed dose was estimated considering two simplified approaches, which allowed to predict upper and lower limit values, and a more complete approach, which included the contribution of single and double scattered radiation. The analytical model developed in this work provided results in a fast and simple way, with a good agreement with those reported by others authors who had used Monte Carlo simulation, as well it allowed to define limit values for detection of tumor masses.
Sêcco, Ney Rafael. "Training artificial neural networks to predict aerodynamic coefficients of airliner wing-fuselage configurations." Instituto Tecnológico de Aeronáutica, 2014. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2955.
Повний текст джерелаOmerdin, Khadijah. "Does Depreciation Matter to Investors?" Scholarship @ Claremont, 2017. http://scholarship.claremont.edu/cmc_theses/1692.
Повний текст джерелаDebbagh-Zriouil, Btissam. "Determination des coefficients de transport pour les lampes a decharge haute pression dans du mercure dope." Toulouse 3, 1987. http://www.theses.fr/1987TOU30263.
Повний текст джерелаGrisales, Catalina Aguirre. "Análises dos transistores de porta flutuante : modelamento e impacto do efeito de doses total ionizante." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/96480.
Повний текст джерелаIn this dissertation work, a study of the the floating gate Transistor (FG transistor) performed. The focus in the electrical modeling, and the analysis of the impact of the Total Ionizing Dose (TID) on the electrical performance of the device. Aiming electrical level simulation, different electric simulation models for the FG transistor in read conditions (DC analysis) were evaluated and the model best suited for implementation into the simulation tool was selected. The selected model is based on Floating Gate voltage calculation as a function of polarization voltage of the FG transistor terminals, the stored charge value in the Floating Gate and the capacitive coupling coefficient presented by this device. For the TID analysis the threshold voltage of the MOS transistor was shifted by means of a Monte Carlo simulation method, considering the threshold voltage variations when the FG transistor is subjected to the ionizing radiation.The analysis lead to the confirmation that the loss charge stored in the FG increases with the radiation dose, affecting the retention characteristics of the memory cells.
Piergallini, Lorenzo. "analisi monte carlo mediante il codice mcnp della dose assorbita dalla lente del cristallino da un operatore sanitario in radiologia interventistica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Знайти повний текст джерелаFeldkircher, Martin, Florian Huber, and Gregor Kastner. "Sophisticated and small versus simple and sizeable: When does it pay off to introduce drifting coefficients in Bayesian VARs?" WU Vienna University of Economics and Business, 2018. http://epub.wu.ac.at/6021/1/wp260.pdf.
Повний текст джерелаSeries: Department of Economics Working Paper Series
Fadaei, Ehsan, and Mohsen Tafazzoli. "Study of the self-diffusion coefficient in the water-methanol binary mixture from the hydrogen bonding viewpoint using DOSY NMR: Study of the self-diffusion coefficient in the water-methanol binary mixturefrom the hydrogen bonding viewpoint using DOSY NMR." Diffusion fundamentals 24 (2015) 13, S. 1, 2015. https://ul.qucosa.de/id/qucosa%3A14527.
Повний текст джерелаPatel, Raj B., and Raj B. Patel. "Prediction of Human Intestinal Absorption." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/624487.
Повний текст джерелаFadaei, Ehsan, and Mohsen Tafazzoli. "Study of the self-diffusion coefficient in the water-methanol binary mixture from the hydrogen bonding viewpoint using DOSY NMR." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-198103.
Повний текст джерелаFalconi, Daniel Rodrigo. "Sensor piezelétrico baseado na tecnologia dos eletretos termo-formados: aprimoramentos dos processos de produção." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18152/tde-20042010-095926/.
Повний текст джерелаThis work describes two improvements on the production of piezoelectric sensors, which are based on thermo-formed electrets technology. These sensors which were previously prepared by fusing and molding two Teflon FEP films into bubbles structures in a hot-press system, presented piezoelectric coefficients over 300 pC/N after properly electrical charging. However, this production system still presents many technical challenges, most of them concerning the bubble formation. With the improvements, called hot lamination and cold adhesive, a much better control of the distribution, height and diameter of the air bubbles could be obtained. These improvements process can be described into four main stages: the molding of one film; the sticking process of the two films; the metallization of their surfaces followed by electric charging. The sticking processes and the previous molding of the film are crucial and the great contribution of this work. With these contributions not only better sensor could be made but it also facilitated the industrial scale implementation of the sensors. Another expressive contribution of this work was the development of a system to measure the piezoelectric coefficient.
Tomal, Alessandra. "Estudo semianalítico da qualidade de imagem e dose em mamografia." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-04042011-145820/.
Повний текст джерелаIn this work, semianalytical models were developed to study the image quality parameters (subject contrast, SC, and contrast-to-noise ratio, CNR) and the normalized average glandular dose (DgN) in conventional and digital mammography. The characteristics of 161 breast tissue samples (linear attenuation coefficient and density), and the mammographic x-ray spectra were determined experimentally, aiming to establish a consistent experimental database of these quantities to be used in the models. The linear attenuation coefficients were determined using a polyenergetic x-ray beam and a Si(Li) detector, and the densities were measured using the buoyancy method. The x-ray spectra from an industrial equipment, which reproduces the mammographic qualities, were measured using Si(Li), CdTe and SDD detectors. The responses of the detectors were determined using Monte Carlo (MC) simulation. The semianalytical models developed in this work allow computing the energy deposited in the breast and in the image receptor, and they were employed to study the SC, CNR and DgN, for different types of breast (thickness and glandularity) and incident x-ray spectra (anode/filter combination, tube potential and half-value layer). These models also allow evaluating the figure of merit (FOM) for conventional and digital mammography. The results of attenuation coefficient and density for the tissues analyzed show similar characteristics for the normal fibroglandular and neoplasic breast tissues, while the adipose tissue presents lower values of these quantities. From the x-ray spectra obtained using each detector, and corrected by their respective responses, it is observed that the three types of detectors can be used to determine mammographic spectra. Detection limits for nodules were estimated from the results of SC and CNR, and they were similar for both cases. The results of SC, CNR and DgN also show the importance of the choice of the breast model, and of the database of attenuation coefficient of breast tissues and x-ray spectra, since they largely influence the studied quantities. Besides, the results for FOM show that, for thin breasts, the Mo/Mo spectrum exhibits the better performance, while the W/Rh and W/Ag spectra are recommended for thicker breasts. For average thickness breasts, the more indicated spectra depend on the employed technique (conventional or digital). Finally, it was verified that the semianalytical models developed in this work provided results in a fast and simple way, with a good agreement with those obtained by using MC simulation. Therefore, these models allow further studies, regarding optimization of mammography, for other breast characteristics and irradiation parameters.
Guzmán, Ediguer Enrique Franco. "Medição de propriedades viscoelásticas de líquidos por ultrassom." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-20082010-165311/.
Повний текст джерелаThe ultrasonic measurement of viscoelastic properties of liquids has been an important research topic since the mid-twentieth century mainly due to the possibility of real-time viscosity measurements. The measurement technique is based on the determination of the complex reflection coefficient (magnitude and phase) of shear waves reflected from the solid-liquid interface. While magnitude measurement is relatively simple and precise, phase measurement is a difficult task due to strong temperature dependence that induces large errors. However, when the measurement is carried out under Newtonian regimen only the magnitude is required. Nonetheless, experimental results reported in literature until now do not agree quantitatively with the theory. In this work, it was developed a novel technique that accurately and precisely determines the reflection coefficient magnitude and, consequently, the Newtonian viscosity. Most tested liquids showed Newtonian behavior at the working frequency of 1 MHz except for some automotive oils of high viscosity, which showed an evident viscoelastic behavior. Deviations up to 12.5% in the dynamic viscosity measurement of substances with relatively simple molecules, such as glycerin and corn syrup, show the technique suitability. A calibration method of the measurement cell allowing the indirect viscosity measurement of a liquid or group of liquids is proposed. Moreover, a new application to oil-in-water contamination monitoring is presented.
Dorigon, Leonardo Jovani. "Determinação dos coeficientes para o modelo da soma-poderada-dos-gases-cinzas a partir do banco de dados HITEMP 2010." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/55459.
Повний текст джерелаIn this work the coefficients for the Weighted Sum-of-Gray-Gases model (WSGG) are determined from HITEMP 2010 database, allowing the use of the model with the most accurate data available nowadays. This study also makes a comparison of the total emittance values obtained from the model with benchmark values, obtained in this work, showing an excellent agreement. With the obtained coefficients, one-dimensional radiant heat transfer problems are solved in order to compare the solution obtained by the WSGG model with the solution obtained by the LBL integration (benchmark solution). In the comparisons, different temperature profiles, path lengths, temperature gradients and species concentrations are used. In all cases it is possible to verify the good agreement of the WSGG and LBL results. For comparisons with parabolic temperature profile, the local error is below 8%. For cosine temperature profile, the local error is about 18% for some cases, but with average errors less than 1,6%.
Galeano, Diego Castanon. "Modificação das posturas dos simuladores antropomórficos voxel de referência Adult Male (AM) e Adult Female (AF) para cálculo de coeficientes de conversão de dose." Universidade Federal de Sergipe, 2016. https://ri.ufs.br/handle/riufs/5274.
Повний текст джерелаEstablish limits to the exposure of the population to various ionizing radiation sources is crucial to prevent occupationally exposed individuals and the public, to their deleterious effects. In computational ambit, it is necessary that different exposure scenarios are simulated in order to obtain the dose coefficients (CCs), which relate physical dosimetric quantities - as absorbed dose, Fluency or Kerma Air - with limiting quantities - as equivalent and / or effective dose. Under certain exposure conditions, the individual's posture is not always the same, and the scenario shall be described as realistic as possible. In this work, the AM (Adult Male) and AF (Adult Female) anthropomorphic reference phantom of ICRP publication n° 110 had their postures modified from supine posture (standing) to sitting posture. The change of posture was performed through of a subroutine written in the Visual Monte Carlo code (VMC) to rotate the thigh region of the phantom and position it between the region of the leg and torso. The ScionImage software was used to reconstruct and smooth the knee and hip contours in a sitting posture phantom, and for 3D visualization of phantom was used VolView software. After this step the MCNPX radiation transport code was used for the calculation of fluence-to-dose conversion coefficients (CCs) to six irradiation geometries: AP, PA, LLAT, RLAT, ROT and ISO, recommended by ICRP. The results were compared between the phantoms in standing and sitting postures, for both sexes, in order to assess differences in scattering and absorption of radiation in different postures. The results show significant differences of up to 100% in the equivalent dose conversion coefficients of organs in the pelvic region, 79 % in organs with distribution in the whole body (such as skin, muscle, lymph nodes, bone marrow and trabecular bone) and a difference of 27% to effective dose conversion coefficients. Moreover in order to conduct a comparative study between two types of simulators, was estimated CCs equivalent and effective dose of adult male hybrid simulators, UFHADM, and female, UFHADF, in a sitting posture, and compared to the AM and AF simulators, also in the sitting posture, where it was observed significant difference in energies below 0.05 MeV. This study demonstrated the feasibility of using anthropomorphic phantoms in the sitting posture to represent more realistic postures and can be used in studies in medical and occupational dosimetry. This study demonstrated the feasibility of using anthropomorphic simulators reference in the seated position to represent more realistic positions can thus be used in studies in medical and occupational dosimetry as well as the importance of developing as realistic simulators as possible to dose estimation as faithful as possible in different irradiation scenarios.
Estabelecer limites à exposição da população a diversas fontes de radiação ionizante é de fundamental importância para prevenir indivíduos, ocupacionalmente expostos e do público, dos seus efeitos deletérios. Em âmbito computacional, é necessário que diferentes cenários de exposição sejam simulados, visando à obtenção dos coeficientes de dose (CCs), que associam grandezas dosimétricas físicas – como dose absorvida, fluência ou kerma no ar – com grandezas limitantes – como equivalente e/ou dose efetiva. Em certas condições de exposição a posição do indivíduo nem sempre é a mesma, e o cenário deve ser descrito da forma mais realística possível. Neste trabalho, os simuladores antropomórficos de referência da publicação nº 110 da ICRP, AM (Adult Male) e AF (Adult Female), tiveram suas posturas modificadas da postura supinada (em pé) para a postura sentada. A mudança de postura foi realizada por meio de uma subrotina escrita no software Visual Monte Carlo (VMC) para rotacionar a região da coxa dos simuladores e posicioná-la entre a região da perna e do tronco. O software ScionImage foi utilizado para reconstruir e suavizar os contornos no joelho e quadril dos simuladores na postura sentada, e com ferramenta auxiliar para visualização 3D dos simuladores foi utilizado o software VolView. Após essa etapa foi utilizado o código de transporte de radiação MCNPX para o cálculo dos coeficientes de conversão (CCs) de dose equivalente e efetiva por fluência de partículas, calculados para seis geometrias de irradiação AP, PA, LLAT, RLAT, ROT e ISO, recomendadas pela ICRP. Os resultados foram comparados entre os simuladores em pé e sentado, para ambos os gêneros, com o objetivo de avaliar as diferenças de espalhamento e absorção da radiação para as diferentes posturas. Os resultados dos CCs mostram diferenças significativas, de até 100 % para dose equivalente dos órgãos situados a região pélvica e 79 % em órgãos com distribuição em todo o corpo como, por exemplo, pele, músculo, nódulos linfáticos medula óssea e trabécula óssea, e uma diferença de 14 % para dose efetiva. Ademais, a fim de realizar um estudo comparativo entre dois tipos de simuladores, foi estimado os CCs de dose equivalente e efetiva dos simuladores híbridos adulto masculino, UFHADM, e feminino, UFHADF, na postura sentada, e comparado com os simuladores AM e AF, também na postura sentada, onde foi observado diferença significativa em energias abaixo de 0,05 MeV. Este estudo demonstrou a viabilidade do uso dos simuladores antropomórficos de referência na postura sentada para representar posturas mais realísticas podendo assim, ser utilizado em estudos na dosimetria médica e ocupacional, bem como a importância de desenvolver simuladores tão realista quanto possíveis para estimativa de dose tão fiéis quanto possíveis em diversos cenários de irradiação.
Melo, Thiago de. ""Enumeração dos fibrados vetoriais sobre superfícies fechadas"." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/55/55135/tde-13052005-193219/.
Повний текст джерелаThe aim of this work is enumerate the plane bundles over some surfaces, for example the sphere and the g-torus. Among other tools we used cohomology of the surfaces with local coefficients and also the method developed by Larmore to count homotopy classes of lifting of functions.
Couto, Maurício Farias. "Classificação da qualidade dos experimentos com cana de açúcar." Universidade Federal de Viçosa, 2010. http://locus.ufv.br/handle/123456789/4025.
Повний текст джерелаThe coefficient of variation as an experimental precision measure has been used for several crops. The present work had as general objective to evaluate the coefficient of variation and the selective accuracy as candidate statistics of experimental precision in essays with sugar cane. Specific objectives: (i) to propose classification ranges of coefficient of variation (CV) in experiments with sugar cane for several variables commonly used by this crop researchers; (ii) to establish adequate limits for the coefficient of variation, with applicability in experiments with sugar cane, considering the must used variables in the essays, through the classification criterion proposed by Costa (2002), taking into consideration the productivity differences along the cuts; (iii) to evaluate the coefficient of variation and the selective accuracy as experimental precision measures in experiments with sugar cane. The data were gotten from exhaustive bibliographic revision in scientific journals, from the sugar cane improvement program database of the Universidade Federal de Viçosa, master degree dissertations, doctor degree thesis and technical reports. Classification ranges were proposed according to the method of Costa (2002), which is based in the use of the median and the pseudo-sigma. The variables height and brix presented the smallest classification ranges of CV, followed by the number of stalks, Pol % of cane and ton of brix per hectare. The variables ton of cane per hectare (TCH), ton of pol per hectare (TPH) and weigh of the plot presented the larges.t classification ranges of the CV All variables presented specific classification ranges, making evident the necessity of considering, in the CV classification, the nature of the studied variable. For the limits of classification by cuts the used data were gotten from the sugar cane improvement program database of the Universidade Federal de Viçosa separated by cuts 1st, 2nd and 3rd. Classification ranges were proposed within each cut. The method proposed by Costa et al (2002) was used, which is based in the use of median and pseudo-sigma. There was disagreement to the specific classification ranges. This result makes evident the necessity of considering, in the classification of CV, the nature of the studied variable and the cuts. The variable TPH and TCH presented wider limits in the classification ranges by cuts. As the objective to propose a selective accuracy evaluation as candidate to the experimental precision classification in essays of the sugar cane genetic improvement program of the Universidade Federal de Viçosa. Analysis of variance were made for the sugar cane productivity data of 111 essays, and collected the values of the statistics: genotype mean square, error mean square, overall mean, value of the F statistic for genotype, and the experimental coefficient of variation. The following statistics were also estimated: genotypic coefficient of variation (CVg), experimental coefficient of variantion (CVe), coefficient of genetic determination between cultivars in the level of plot (h2) and selective accuracy (SA). For a safe inference, the F values for sugar cane cultivations must be equal or superior to 5.05, experiments with F values under 1.17 must be discharged, therefore they don t attend to the minimum accuracy. The SA presents itself as a possible candidate to classify experiments coming from the sugar cane improvement genetics program for taking into consideration the attributes, repetitions number, environmental variation and genetics, as became demonstrated in this work.
O coeficiente de variação como medida de precisão experimental tem sido utilizado para diversas culturas. O presente trabalho teve como objetivo geral avaliar o coeficiente de variação e acurácia seletiva como estatísticas candidatas a precisão experimental em ensaios com cana de açúcar. Objetivos específicos: (i) Propor faixas de classificação do coeficiente de variação em experimentos com cana de açúcar para diversas variáveis utilizadas por pesquisadores da cultura; (ii) estabelecer limites adequados para o coeficiente de variação, com aplicabilidade em experimentos com cana de açúcar, considerando as variáveis mais utilizadas nos ensaios, através do critério de classificação proposto por Costa (2002), levando em consideração as diferenças de produtividade ao longo dos cortes; (iii) Avaliar o coeficiente de variação e a acurácia seletiva como medidas de precisão experimental em experimentos com cana de açúcar. Para esse estudo foram consideradas algumas das variáveis mais utilizadas por pesquisadores desta cultura. Os dados foram obtidos de extensa revisão bibliográfica em revistas científicas, banco de dados do programa de melhoramento de cana de açúcar da Universidade Federal de Viçosa, dissertações de mestrado, teses de doutorado e relatórios técnicos. Foram propostas faixas de classificação segundo o método de Costa (2002), o qual se baseia no uso da mediana e do pseudo-sigma. As variáveis altura e brix apresentaram as menores faixas de classificação de CV, seguidas pelo número de colmos, Pol % da cana e tonelada de brix por hectare. As variáveis tonelada de colmo por hectare, tonelada de pol por hectare e peso da parcela apresentaram as maiores faixas de classificação do coeficiente de variação. Todas as variáveis apresentaram faixas de classificação específica, evidenciando a necessidade de se considerar, na classificação dos CV, a natureza da variável estudada. Para os limites de classificação por cortes os dados utilizados foram obtidos do banco de dados do programa de melhoramento de cana de açúcar da Universidade Federal de Viçosa separados por cortes 1º, 2º e 3º. Foram propostos faixas de classificação dentro de cada corte. Para isso utilizou-se o método proposto por Costa et al. (2002). Houve discordância quanto às faixas de classificação por corte para cada variável, acarretando em faixas de classificação especifica. Este resultado evidencia a necessidade de se considerar, na classificação dos CV, a natureza da variável estudada e os cortes. A variável TPH e TCH apresentaram maiores limites nas faixas de classificação por cortes. Com o objetivo de propor uma avaliação da acurácia seletiva como candidata a precisão experimental em ensaios do programa de melhoramento genético da cana de açúcar da Universidade Federal de Viçosa. Foram realizadas análises de variância para os dados de produtividade de cana de açúcar de 111 ensaios, e coletados os valores das estatísticas: quadrado médio do genótipo, quadrado médio do erro, média geral do ensaio, valor do teste F para genótipo e coeficiente de variação experimental. A seguir, foram estimadas as estatísticas, coeficiente de variação genotípica (CVg), coeficiente de variação experimental (CVe), herdabilidade (h2), acurácia seletiva (AS). Valores de F para as cultivares de cana de açúcar devem ser iguais ou superiores a 5,05 pra se obter uma acurácia tida como ideal (≥ 0,90). Experimentos com valores do F abaixo de 1,17 devem ser descartados, pois não atendem a uma acurácia mínima. Concluiu-se que o coeficiente de variação é uma estatística recomendada para avaliar a precisão experimental em experimentos com cana de açúcar com médias semelhantes ou de mesmo corte, pois para cada corte existe limites de classificação diferenciado. A acurácia seletiva apresentou-se como uma candidata viável para classificar experimentos advindos do programas de melhoramento genético da cana de açúcar por levar em consideração os atributos número de repetições e as variações ambiental e genética como ficou demonstrado neste trabalho.
Thorne, Terrill D. "Does the Relative Price of Non-Traded Goods Contribute to the Short-Term Volatility in the U.S./Canada Real Exchange Rate? A Stochastic Coefficient Estimation Approach." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/31159.
Повний текст джерелаMaster of Arts
Guerrero, André de Oliveira. "Aplicação da termodinâmica dos meios homogêneos ao estudo de estados metaestáveis e instáveis." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249917.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: A equação original de van der Waals é alterada de modo a aprimorar sua aderência a dados experimentais para o Argônio, desde as baixas densidades dos estados gasosos até as altas densidades dos líquidos e dos vidros. Isto permite a obtenção de uma curva spinodal (fronteira termodinâmica entre os estados não acessíveis pela matéria e os estados possíveis, estáveis ou não) mais precisa do que a atualmente disponível, além de fornecer subsídios para estudos de líquidos e gases não estáveis. A pressão repulsiva original é substituída pela pressão de um sistema de esferas rígidas, enquanto que a pressão atrativa original é substituída pela pressão de um campo médio isotrópico descrito por três parâmetros. A realização destas alterações propicia a discussão de diversos aspectos da interpretação física da equação de van der Waals. Como os estados considerados são homogêneos, mas não necessariamente estados de equilíbrio, a temporal termodinâmica dos meios homogêneos é uma teoria adequada à descrição dos estados representados pela equação alterada.
Abstract: The original van der Waals equation is altered to improve its quantitative description of argon experimental values, including those of low density gaseous states and high density liquids and glasses. A spinodal curve is obtained (the limit between thermodynamically forbidden and permitted states of matter, either stable or unstable) that is more precise than the one actually available and reveals more information for studying unstable gases and liquids. The pressure of a rigid spheres system substitutes the original repulsive pressure, while the pressure of an isotropic mean field defined by three parameters substitutes the original attractive pressure. Implementing these substitutions provokes the discussion of several aspects, related to the physical meaning of van der Waals equation. Since only homogeneous states are considered, although they are not necessarily equilibrium states, time dependent thermodynamics of homogeneous media is an adequate theory to describe the states represented by the altered equation.
Mestrado
Físico-Química
Mestre em Química
Almeida, Vitor dos Santos. "An?lise de mistura de componentes de ?leo decantado por meio de DOSY/RMN auxiliada por matrizes." Universidade Federal Rural do Rio de Janeiro, 2016. https://tede.ufrrj.br/jspui/handle/jspui/1437.
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The analysis of mixtures is a common place challenge in the laboratory. Conventional methods demand a previous treatment which may be time consuming. At present, Nuclear Magnetic Resonance may be employed for the analysis of mixtures by using the DOSY (diffusion ordered spectroscopy) technique, whereby the different components of a mixture are separated by their diffusion coefficients. Pitches, in general, are products which are employed as starting material for the production of a variety of carbon materials, such as anodes for the production of aluminum, graphite electrodes for the steel industry, and carbon fibers. Pitches obtained from coal tar, itself a residue in the production of coke, are the most traditionally used. However, it is a carcinogen and therefore has had its use greatly diminished. Petroleum pitches, which are produced from decanted oil, may be a safer and less expensive alternative. The decanted oil is a heavy fraction obtained from catalytic cracking of petroleum. The difficulties in controlling its processing are derived from its complex composition, which includes paraffins, aromatic and heteroaromatic compounds. The present work investigates the analysis by NMR-DOSY of a mixture of model compounds present in decanted oil. Thus, a mixture of Tetracosane, Phenanthrene, 9-Mehylanthracene, Pyrene, Carbazole, 9-metil Carbazol, Dibenzothiophene, Dibenzofuran, Hexadecane, 1-Methylnaphthalene, Thiophene, Tetrahydrofuran was analyzed by NMR with an Avance III 500 MHz NMR spectrometer equipped with a BBO probe with a gradient on z-axis, at 20?C. To help in the separation by diffusion, the following polymers were used: poly-(ethyleneglycol), poly-(vinylpyrrolidone), poly-(dimethylsiloxan), poly-(butylmethacrylate) e poly-(vinylacetate).The shift reagent Eu(fod)3 was also employed. The results from DOSY-INEPT experiments show that poly-(butylmethacrylate) is the matrix which afforded the best separation of the different components of the mixture, followed by poly-(vinylacetate), poly-(ethyleneglycol) and finally, poly-(vinylpyrrolidone), which showed satisfactory results
Um grande desafio, muitas das vezes at? comum nos laborat?rios, ? a an?lise de misturas. Os m?todos convencionais em sua maioria exigem um tratamento pr?vio das misturas, o que demanda tempo, al?m de interferir diretamente no equil?brio do sistema. Hoje em dia, a t?cnica de Resson?ncia Magn?tica Nuclear pode ser usada na an?lise de misturas medindo-se o coeficiente de difus?o dos componentes da mistura, permitindo a obten??o dos espectros de cada componente individualmente por meio de um experimento r?pido que n?o interfere na mistura em si. O experimento mais comum ? o DOSY, do ingl?s Espectroscopia de Difus?o Ordenada. Piches, em geral, s?o produtos que s?o empregados como mat?rias-primas na produ??o de uma variedade de materiais de carbono, tais como: anodos de carbono para produ??o de alum?nio, eletrodos de grafite para a ind?stria sider?rgia e fibras de carbono. Piches obtidos a partir do alcatr?o da hulha, res?duo da produ??o de coque metal?rgico, s?o os tradicionalmente mais usados, mas apresentam alto potencial carcinog?nico e tem demanda decrescente em fun??o de novas tecnologias empregadas nas coquerias. Piches de petr?leo, produzidos a partir de ?leos decantados, podem potencialmente constituir uma alternativa mais segura e com maior disponibilidade. O ?leo decantado ? uma fra??o pesada obtida nas unidades de craqueamento catal?tico fluido no refino de petr?leo, e o controle de seu processamento ? dificultado pela complexidade de sua composi??o, que inclui compostos paraf?nicos, homoarom?ticos e heteroarom?ticos. O presente trabalho se prop?em a investigar a an?lise por RMN de uma mistura de padr?es de subst?ncias representativas dos tipos de compostos presentes no ?leo decantado. Assim, foram escolhidos padr?es de Tetracosano, Fenantreno, 9-metil Antraceno, Pireno, Carbazol, 9-metil Carbazol, Dibenzotiofeno, Dibenzofurano, Hexadecano, 1-metil Naftaleno, Tiofeno, Tetrahidrofurano. Todos os experimentos foram realizados no laborat?rio de RMN do PPGQ-UFRRJ a 20?C com o espectr?metro de RMN de 500 MHz Bruker Avance III, equipado com sonda BBO, gradiente no eixo z. Para auxiliar na separa??o dos componentes da mistura foram usados o pol?mero poli-(etilenoglicol), poli-(vinilpirrolidona), poli-(dimetilsiloxano), poli-(metacrilato de butila) e poli-(acetato de vinila), al?m do reagente de deslocamento Eu(fod)3. Os resultados obtidos a partir dos experimentos de DOSY-INEPT mostraram que o pol?mero PMAB foi a matriz que mais auxiliou na separa??o dos componentes da mistura em quest?o no presente trabalho, sendo seguido pelas matrizes PAV, PEG e PVP, que tamb?m apresentaram resultados satisfat?rios
Vela, Connie Gallardo. "Balanço de nutrientes, uso aparente da energia e digestibilidade ileal aparente e estandardizada dos aminoácidos do farelo do trigo, farelo de arroz, sorgo, farelo de canola, farelo de girassol, milho, farelo de soja e soja integral extrusada, com inclusão isolada e combinada de multi-carboidrase e fitase, em frangos de corte dos 14 aos 21 dias de idade." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/10/10135/tde-20022017-084441/.
Повний текст джерелаThe aim of this study was to determine the effects of multi-carbohydrase (MC, that consist in: galactomannanase, xylanase, beta-glucanase and alpha-galactosidase) and phytase (10000 FTU/g of activity) the nutrients balance, apparent energy use (AME), apparent and standardized ileal amino acids digestibility in some feedstuffs fed to young chickens. Under a completely randomized design 1960 male broilers (Cobb 500) were allotted from 1 to 21 days old to receive five treatments in seven replicates with seven birds each. Birds cages adaptation under dietary nutritional levels recommended to the stage occurred from the 1st to 10th day of age. Then, the birds received the experimental diet from 11 to 18 days when was realized the excreta collection, period defined as Assay 1. From the 19th day the birds received the new diet until 21 days old when birds were slaughter for ileal digesta collection, this period was defined like Assay 2. The experimental diets were: one reference diet and four corn-based diets (Assay 1) and four corn-starch-based diets (Assay 2). The experimental diets containing 30% of ingredient test as a sole protein source in 2 MC (0 or 200 mg/kg) x 2 phytase (0 or 50 mg/kg) factorial arrangement. The ingredients tested were: wheat bran, rice bran, sorghum, canola meal, sunflower meal, corn, soybean meal and extruded soybean meal. Data were subjected to variance analysis using the PROC GLM of SAS 9.2. Enzymes improved (P < 0.05) the nutrients balance, AME use, apparent and standardized ileal amino acids digestibility on different tested ingredients. Isolated or combined the multi-carbohydrase and phytase have different efficiency for each studied ingredient and used on feed formulation for broiler chickens in initial phase, that corresponding from 14 to 21 days old
Lang, Jean Pierre. "Avaliação do efeito dos parametros operacionais e geometricos sore a eficiencia de uma coluna de destilação Higee." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267229.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: As colunas de recheio são equipamentos intensamente aplicados em operações de separação tais como destilação, absorção de dessorção. No entanto, a sua capacidade à transferência de massa em contracorrente é limitada devido à sua inundação. Uma nova tecnologia HIGEE ('high g¿ ¿ alta gravidade é proposta para superar esta limitação. Uma cluna HIGEE utiliza um recheio rotativo que induz acelerações centrífugas acima de 1000 vezes a aceleração da gravidade terrestre. O aumento da força motriz permite o aumento da capacidade e da eficiência da coluna. De acordo com vários autores, o tamanho do equipamento fica consideravelmente reduzido, apresentando vantagens econômicas e operacionais. A principal proposta deste trabalho é avaliar a forma como a coluna com recheio rotatico se comporta quando o raio externo do rotos é aumentado de 8 (Nascimento, 1999 e 2003) para 13cm.Os experimentos foram conduzidos em condições de refluxo total, sendo utilizando dois sistemas destilantes: n-hexano/n-heptano e etanol/água. A velocidade do rotor foi variada de 500 a 2300 rpm, criando acelerações contrifugas de 26 a256 vezes a aceleração da gravidade. O efeito da vazão de vapor, velocidade de rotação e do sistema destilante sobre o coeficiente de transferência de massa, 'K IND. y¿¿a IND. e¿ depende do fluxo de vapor, mas fracamente da velocidade do rotor...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: Packed colummns are equipment intensively applied in separations such as distillation, absorption and stripping , absorption and strippig. However, its for counter-current mass transfer is limited due to its flooding. A new HIGEE (high g ¿ high gravity) technology is proposal to overlap this limitation. A HIGEE column uses a rotating machine that promotes centrifugal accelerations above 1000 times the terrestrial gravity acceleration. The increase of the driving force allows the increase of column¿s capacity and efficiency. In accordance with some authors, the equipment size considerably reduced presenting economic and operational advantages. The main proposal of this work is to evaluate how the mass transfer behavior of the HIGEE column changes when the external rotor radius is increased from 8 (Nascimento 1999 and 2003) to 13 cm. The experiments had been conduced in total reflux conditions using two distilling system n-hexane/n-heptane and ethanol/ water. The rotor's speed was vaied from 500 to 2300 rpm , provided centrifugal accelerations from 26 to 556 times higher than terrestrial gravity acceleration. The effect of the vapor outflow, rotation speed and distilling system on mass transfer coefficient 'K IND. y¿¿a IND. e¿ and transfer unit area, 'AUT IND. G¿had been analyzed for each rotor size...Note: The complete abstract is available with the full electronic digital thesis or dissertations
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
Costa, Mônica Sarolli Silva de Mendonça 1969. "Caracterização dos dejetos de novilhos superprecoces : reciclagem energética e de nutrientes /." Botucatu : [s.n.], 2005. http://hdl.handle.net/11449/101718.
Повний текст джерелаBanca: Mario Benincasa
Banca: Roberto Alves de Oliveira
Banca: Edson Aparecido Abdul Nour
Banca: Simone Damasceno
Resumo: Com o objetivo de caracterizar quantitativa e qualitativamente os dejetos produzidos em um sistema de confinamento para criação de novilhos superprecoces e avaliar o desempenho de processos biológicos de reciclagem de nutrientes: compostagem, vermicompostagem e biodigestão anaeróbia, conduziu-se esta pesquisa. O trabalho foi dividido em quatro ensaios: caracterização dos dejetos, compostagem, vermicompostagem e biodigestão anaeróbia. O ensaio de caracterização dos dejetos teve como objetivo principal determinar o coeficiente de resíduo para o período de confinamento. Nos ensaios de compostagem e vermicompostagem objetivou-se avaliar o desempenho dos processos utilizando-se dejetos produzidos por animais que receberam três dietas (dieta 1: 65% concentrado + 35% volumoso; dieta 2: 70% concentrado + 30% volumoso e dieta 3:75% concentrado + 25% volumoso), oferecidas aos animais durante o período de engorda. No ensaio de biodigestão anaeróbia, foram avaliados os efeitos de duas dietas (dieta 1: 65% concentrado + 35% volumoso e dieta 2: 80% concentrado + 20% volumoso), uso de inóculo e três níveis de temperatura (40º C, 35º C e 25º C) sobre a produção de biogás. O coeficiente de resíduo encontrado, considerando todo o período de engorda, foi de 3,03, ou seja, para cada quilo de animal produzido, gerou-se 3,03 kg de dejeto (matéria seca). Considerando todo o período de confinamento, 154 dias, cada animal gerou 515,4 kg de dejeto (matéria seca) ou 2577 kg (fezes + urina), os quais em termos de nutrientes produzidos por animal representam 12,4 kg de N; 8,8 kg de P2O5; 6,7 kg de K2O; 397,0 kg de MO; 219,6 kg de C; 13,9 kg de Ca; 2,6 kg de Mg; 1,6 kg de S; 2,2 kg de Na; 0,05 kg de Cu; 1,0 kg de Fe; 0,06 kg de Mn; 0,11 kg de Zn. Os valores dos componentes da análise bromatológica dos dejetos foram 14% de PB; 20,7% de FB; 2,2% de EE; 51,9% de FDN; 33,3% de FDA; ...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The present study aimed to quantify wastes produced in a confined system for steers breeding and to evaluate the performance of biological process such as nutrient recycling, composting, vermicomposting and anaerobic biodigestion. Four trials were performed: wastes characterization, composting, vermicomposting and anaerobic biodigestion. The waste characterization trial aimed to determine the residual coefficient while animals were confined. The composting and vermicomposting trials were conducted in order to evaluate the process performance by using wastes products from animal fed three differents diets (diet 1: 65% concentrated + 35% voluminous ; diet 2: 70% concentrated + 30% voluminous; diet 3: 75% concentrated + 25% voluminous). The effect of two different diets (diet 1: 65% concentrated + 35% voluminous and diet 2: 80% concetrated + 20% voluminous), inoculum and three temperatures rates (40º C, 35º C e 25º C) influence all over biogas production were evaluated during the biodigestion trial. The residue coefficient found during all confined period was 3.03, whereas, to produce one kilogram body weight, 3.03 kg of waste (dry matter) was produced. During all confined period (154 days), each animal produced 515.4 kg of waste (dry matter) or 2577 kg (feces + urine), wich represents in terms of nutrients produced per animal a total of: 12.4 kg of N; 8.8 kg of P2O5 ; 6.7 kg of K2O ; 397.0 kg of OM ; 219.6 kg of C; 13.9 kg of Ca; 2.6 kg of Mg; 1.6 kg of S; 2.2 kg of Na; 0.05 kg of Cu; 1.0 kg of Fe; 0.06 kg of Mn; 0.11 kg of Zn. Bromatological analysis values of waste were: 14% of PB; 20,7% of FB; 2,2% of EE; 51,9% of FDN; 33,3% of FDA; 48,2% of ENN e 63,16% of NDT. Percentage of dry matter redution during composting trial were: 44.5%; 40.5% and 43.8% for waste produced by animals that received diets 1, 2 and 3, respectively...(Complete abstract click electronic access below)
Doutor
Wysmierski, Philip Traldi. "Contribuição genética dos ancestrais da soja às cultivares brasileiras." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-11022011-105217/.
Повний текст джерелаSoybean is a very important oilseed in the world economy. Brazil is the second largest producer, behind the USA, highlighting the importance of this crop for the country. Genetic diversity is needed for genetic progress, and one manner of estimating the genetic diversity of a group is through the concept of a genetic base, which can be defined as the number of ancestors and their relative genetic contribution (RGC) to each cultivar. The RGC can be estimated through the coefficient of parentage between the ancestors and the cultivars. Previous studies had determined that the genetic base of Brazilian soybean was very narrow, with only four ancestors representing 48.16% of the genetic base. The general objective of this work was to evaluate the pedigree of 444 Brazilian soybean cultivars to estimate their genetic base. The cultivars were also divided according to their release dates (before 1971, 1971-1980, 1981-1990, 1991-2000 e 2001- 2009) or according to their origin (public or private) and the genetic base for each group was also estimated. The results were compared to data from similar studies involving molecular markers. A total of 60 ancestors contribute to these 444 cultivars. The four main ancestors (CNS, S-100, Nanking and Tokyo) contribute with 55.26% of the genetic base and only 14 ancestors contribute with more than 1.00% individually to the genetic base. Therefore, these 14 ancestors represent 92.41% of the genetic base of Brazilian soybean. These results indicate that the genetic base of Brazilian soybean is very narrow, and it is also very similar to the genetic base of soybean in the USA, with which it shares six of its main ancestors. The analysis of the release dates indicates that there has been an increase of ancestors over time, but the four main ancestors were the same over all periods, and their cumulative RGC went from 46.60% (before 1971) to 57.59% (2001-2009), indicating a narrowing of the genetic base. The new ancestors incorporated over time presented very low contributions, and in many cases were only used to incorporate specific qualitative characteristics. The 301 public cultivars had 58 ancestors and their RGC was very similar to the total number of cultivars. The private cultivars had only 37 ancestors, which may have been caused by the lower number of cultivars analyzed (112), but the RGC of the main ancestors was also very similar to the general genetic base. Therefore, we conclude that (a) the current genetic base of Brazilian soybean remains narrow, in spite of the incorporation of new ancestors; (b) the genetic base has become more narrow over time, with an increase in the RGC of the main ancestors; (c) there is no difference in the RGC of the main ancestors between public and private cultivars and (d) the results of this study are supported by molecular marker data from some works, but differs from others.
Bachmann, Sebastian. "Estimating Molecular Weights of Organometallics in Solution with Diffusion NMR Techniques." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://hdl.handle.net/11858/00-1735-0000-0023-3DF9-7.
Повний текст джерелаCoelho, Welington Ricardo [UNESP]. "Análise do fenômeno de cavitação em bomba centrífuga." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/88879.
Повний текст джерелаCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Cavitação em bombas centrífugas é a formação de bolhas de vapor do fluido bombeado na região de sucção do equipamento. As bolhas de vapor formadas em algum local do escoamento, em geral na região de sucção da bomba, entrarão posteriormente em colapso. Este fenômeno é importante cientificamente, tecnicamente e economicamente. Cientificamente é interessante, pois envolve o escoamento de um fluido em estado líquido, simultaneamente ocorre a formação de bolhas de vapor, que também escoam juntamente ao fluido líquido. O processo de vaporização e condensação de um fluido é complexo, pois envolve mudança de fase, um fenômeno térmico não linear. Tecnicamente, é importante porque quando o escoamento se dá com cavitação os parâmetros hidrodinâmicos do escoamento bem como da bomba, em geral, são fortemente alterados na direção termodinâmica de maior produção de irreversibilidades. Economicamente, é custoso porque a cavitação, em geral, leva a perda de eficiência termodinâmica dos processos e em conseqüência haverá maior custo na produção de um dado bem, diminuindo a eficiência econômica e a competitividade da empresa. O escoamento com cavitação na sucção de bombas apresenta três aspectos danosos principais: cavitação pulsante com baixa vazão; cavitação não pulsante com baixa altura útil; e erosão cavitacional. A cavitação pulsante é caracterizada por grande formação de bolhas de forma transitória com baixa freqüência e grande amplitude, gerando forças vibratórias importantes no sistema de bombeamento. A cavitação pulsante também causa colapso do fluxo de massa do fluido bombeado com valores que vão do fluxo normal da instalação até valores quase nulos, transitoriamente. Na cavitação pulsante a erosão cavitacional e a queda na altura útil são pequenas...
Cavitation in centrifugal pumps is the development of vapor bubbles from the pumped liquid into equipment suction region. Vapor bubbles developed somewhere in the flow, generally in the pump suction, will afterwards along the flow to collapse. This phenomenon is scientifically, technically and economically important. Scientifically, it is interesting because involves the flow of a fluid on liquid state, and simultaneously happens vapor bubbles development that also flow together the liquid fluid. Fluid vaporization and condensation processes are complex because involves phase change, a non-linear thermal phenomenon. Technically, it is important because when the flow happens with cavitation the flow and pump hydrodynamic parameters, generally, are strongly modified toward bigger thermodynamic irreversibility production. Economically, it is expensive because cavitation, generally, leads to thermodynamic process efficiency loss, and consequently it will have bigger costs for production of a given good, then decreasing economic efficiency and company competitiveness. Flow with cavitation in the pump suction presents three main devastating aspects: surging cavitation with low flow rate; steady cavitation with low total head; and cavitational erosion. Surging cavitation is characterized by unsteady, low frequency and high amplitude, intense bubbles development, producing strong vibration forces into the pumping system. Surging cavitation also causes the collapse of pumped fluid mass flow rate with values that goes from the normal flow to values that almost reach the zero flow, unsteadily. In surging cavitation, the cavitational erosion and the breakdown in total head are small. In steady cavitation the mass flow rate, and even the flow rate... (Complete abstract click electronic access below)
Costa, Mônica Sarolli Silva de Mendonça [UNESP]. "Caracterização dos dejetos de novilhos superprecoces: reciclagem energética e de nutrientes." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/101718.
Повний текст джерелаCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Universidade Estadual Paulista (UNESP)
Com o objetivo de caracterizar quantitativa e qualitativamente os dejetos produzidos em um sistema de confinamento para criação de novilhos superprecoces e avaliar o desempenho de processos biológicos de reciclagem de nutrientes: compostagem, vermicompostagem e biodigestão anaeróbia, conduziu-se esta pesquisa. O trabalho foi dividido em quatro ensaios: caracterização dos dejetos, compostagem, vermicompostagem e biodigestão anaeróbia. O ensaio de caracterização dos dejetos teve como objetivo principal determinar o coeficiente de resíduo para o período de confinamento. Nos ensaios de compostagem e vermicompostagem objetivou-se avaliar o desempenho dos processos utilizando-se dejetos produzidos por animais que receberam três dietas (dieta 1: 65% concentrado + 35% volumoso; dieta 2: 70% concentrado + 30% volumoso e dieta 3:75% concentrado + 25% volumoso), oferecidas aos animais durante o período de engorda. No ensaio de biodigestão anaeróbia, foram avaliados os efeitos de duas dietas (dieta 1: 65% concentrado + 35% volumoso e dieta 2: 80% concentrado + 20% volumoso), uso de inóculo e três níveis de temperatura (40º C, 35º C e 25º C) sobre a produção de biogás. O coeficiente de resíduo encontrado, considerando todo o período de engorda, foi de 3,03, ou seja, para cada quilo de animal produzido, gerou-se 3,03 kg de dejeto (matéria seca). Considerando todo o período de confinamento, 154 dias, cada animal gerou 515,4 kg de dejeto (matéria seca) ou 2577 kg (fezes + urina), os quais em termos de nutrientes produzidos por animal representam 12,4 kg de N; 8,8 kg de P2O5; 6,7 kg de K2O; 397,0 kg de MO; 219,6 kg de C; 13,9 kg de Ca; 2,6 kg de Mg; 1,6 kg de S; 2,2 kg de Na; 0,05 kg de Cu; 1,0 kg de Fe; 0,06 kg de Mn; 0,11 kg de Zn. Os valores dos componentes da análise bromatológica dos dejetos foram 14% de PB; 20,7% de FB; 2,2% de EE; 51,9% de FDN; 33,3% de FDA;...
The present study aimed to quantify wastes produced in a confined system for steers breeding and to evaluate the performance of biological process such as nutrient recycling, composting, vermicomposting and anaerobic biodigestion. Four trials were performed: wastes characterization, composting, vermicomposting and anaerobic biodigestion. The waste characterization trial aimed to determine the residual coefficient while animals were confined. The composting and vermicomposting trials were conducted in order to evaluate the process performance by using wastes products from animal fed three differents diets (diet 1: 65% concentrated + 35% voluminous ; diet 2: 70% concentrated + 30% voluminous; diet 3: 75% concentrated + 25% voluminous). The effect of two different diets (diet 1: 65% concentrated + 35% voluminous and diet 2: 80% concetrated + 20% voluminous), inoculum and three temperatures rates (40º C, 35º C e 25º C) influence all over biogas production were evaluated during the biodigestion trial. The residue coefficient found during all confined period was 3.03, whereas, to produce one kilogram body weight, 3.03 kg of waste (dry matter) was produced. During all confined period (154 days), each animal produced 515.4 kg of waste (dry matter) or 2577 kg (feces + urine), wich represents in terms of nutrients produced per animal a total of: 12.4 kg of N; 8.8 kg of P2O5 ; 6.7 kg of K2O ; 397.0 kg of OM ; 219.6 kg of C; 13.9 kg of Ca; 2.6 kg of Mg; 1.6 kg of S; 2.2 kg of Na; 0.05 kg of Cu; 1.0 kg of Fe; 0.06 kg of Mn; 0.11 kg of Zn. Bromatological analysis values of waste were: 14% of PB; 20,7% of FB; 2,2% of EE; 51,9% of FDN; 33,3% of FDA; 48,2% of ENN e 63,16% of NDT. Percentage of dry matter redution during composting trial were: 44.5%; 40.5% and 43.8% for waste produced by animals that received diets 1, 2 and 3, respectively...(Complete abstract click electronic access below)
Pintao, Carlos Alberto Fonzar. "Novo arranjo para determinar os coeficientes de emissão e a distribuição de energia dos elétrons secundários emitidos por sólidos." Universidade de São Paulo, 1996. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14112007-091415/.
Повний текст джерелаA new arrangement of measure was developed in this study, in order to obtain the energy distribution from the emitted secondaries and the emission yields by a solid. Because this arrangement allowed the direct measurement of the surface potential, in the case of metals, it was possible to apply and describe theoretically the mensuration method employed, to determine the energy distribution of the secondaries to platinum, Teflon-FEP. Mylar, PVDF α, PVDF- β and thie conducting polymer. The charges accumulated during the polymers irradiation were compensated through the electronic beam itself. This proceeding is not very usual, as referring to the ones applied in literature, and it proved to be very efficacious. The dynamic method was employed for the first time to metals in order to determine the total emission yield in function of the energy of the inciding electrons and it was found out that these results were identical to the ones obtained through the pulse method. As a natural development, by applying the dynamic method to metals, the measurements achieved were also applied to golden layers 50 nm, 10 nm and 2,5 nm wide deposited on Teflon-FEP, and they gave birth to the two layers, in the interpretation of the experimental results.
Florindo, Caio César Ferreira 1988. "Estudo de estados estáveis e não estáveis através da termodinâmica dos processos homogêneos em meios contínuos." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249873.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: O presente trabalho tem três metas principais: (1) usar as transformações de Levin para estimar coeficientes viriais e avaliar a qualidade das estimativas; (2) inserir adaptações, coerentes com as transformações de Levin, na equação original de van der Waals, de modo a aprimorar sua capacidade de se aproximar de dados experimentais para estados estáveis; (3) extrapolar a equação adaptada, para possibilitar o estudo de estados não estáveis. Os resultados indicam que as transformações de Levin podem ser usadas como uma forma aproximada de representar a série virial, porque os coeficientes viriais de alta ordem, por elas estimados, estão em boa concordância com os valores obtidos na literatura. A utilização das representações de Levin para a adaptação do termo repulsivo da equação de van der Waals, juntamente com uma alteração proposta para o termo atrativo, produz isotermas subcríticas e supercríticas em boa concordância com os dados experimentais e proporciona aprimoramento da previsão do comportamento do sistema. As novas equações podem ser aplicadas tanto em densidades referentes à região de fase gasosa, como de fase líquida. Devido às boas previsões de resultados produzidas pelas equações desenvolvidas neste trabalho, são obtidas curvas spinodais com um nível de exatidão muito superior àquele encontrado na literatura. Portanto, o presente trabalho descreve equações aprimoradas que representam estados estáveis tão bem que podem ser extrapoladas para estados não estáveis
Abstract: This work aims at three main goals: (1) to use Levin's sequence transformations for estimating virial coefficients, and to assess the quality of the estimates; (2) to insert in the van der Waals equation some modifications consistent with the Levin's sequence transformations, enhancing its ability to approximate experimental data for stable states; (3) to extrapolate the modified equation for studying unstable states. The results indicate that the Levin's sequence transformations can be used as an approximate way to represent the virial series, because the high order estimated virial coefficients are in good agreement with values reported in literature. The use of the Levin's sequence transformations for modifying the repulsive term of van der Waals equation, together with a proposed attractive term improvement, yields subcritical and supercritical isotherms in good agreement with experimental data and provides better predictions of the behavior of the system. The new equations can be applied both at densities corresponding to gaseous and liquid phases. According to the good predictions of experimental results produced by the equations developed in this work, spinodal curves which are much more accurate than those found in literature are obtained. Therefore, this work describes improved equations that represent stable states well enough to accept extrapolation to unstable states
Mestrado
Físico-Química
Mestre em Química
Santos, Clenilton Costa dos. "Propriedades ópticas dos vidros Er3+:PbPO4." reponame:Repositório Institucional da UFC, 2010. http://www.repositorio.ufc.br/handle/riufc/9652.
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In this work we employ several techniques to investigate the optical properties of moderately high Er3+-doped lead phosphate (EDLP) glasses. The third-order optical susceptibility, χ3, and dispersion of the linear refractive index, n0(λ), of Er3+:PbPO4 were measured in the wavelength range between 400 and 1940 nm by using the spectrally resolved femtosecond Maker fringes technique. The nonlinear refractive index, n2, obtained from the third-order susceptibility was found to be five times higher than that of silica. For comparison purposes, the Z-scan technique was also employed to obtain the values of n2 of EDLP at several wavelengths, and the values obtained using the two techniques agree to within 15%. From the data obtained by absorption measurements, the Judd-Ofelt theory was employed to calculate the intensity-dependent parameters Ωλ (λ = 2, 4, and 6). We observed that increasing Er3+ content, Ω4 and Ω6 remain constant, while Ω2 decreases. Green, red, and infrared emissions centered at 530, 550, 660, and 1530 nm were observed under excitation at 800 nm. The lifetime of the Er3+: 4I13/2 → 4I15/2 (1530 nm) transition decreases with increasing Er3+ content, reflecting how significant the non-radiative process associated with this transition is. The McCumber theory was used to calculate, from absorption cross-section, the stimulated emission cross-section of the Er3+: 4I13/2 → 4I15/2 transition. A strong re-absorption of the fluorescence at 1530 nm was also observed and analyzed. Finally, we discuss the potential use of Er3+:PbPO4 glasses in photonics devices.
Neste trabalho utilizamos várias técnicas para investigar as propriedades ópticas dos vidros fosfato de chumbo (PbPO4) com concentrações moderadamente altas de íons de érbio (Er3+), EDLP. Medimos a susceptibilidade de terceira ordem, χ3, e a dispersão do índice de refração linear, n0(λ), dos vidros EDLP na região de comprimento de onda entre 400 e 1940 nm, por meio da técnica de Franjas de Maker. A partir do valor de χ3, calculamos o índice de refração não-linear, n2, cujo valor é cerca de cinco vezes maior que o da sílica (SiO2). Também obtivemos os valores de n2 dos vidros EDLP, através da técnica de varredura Z para vários comprimentos de onda. A diferença entre os valores obtidos pelas duas técnicas foi de 15%. Realizamos medidas de absorção óptica, cujos dados foram utilizados para calcular os parâmetros fenomenológicos Ωλ da teoria de Judd-Ofelt. Observamos que Ω4 e Ω6 permanecem praticamente constante com o aumento da concentração de Er3+, ao passo que Ω2 diminui. Excitando as amostras em 800 nm foi possível verificar emissões no verde, vermelho e infravermelho, centradas em 530, 550, 660 e 1530 nm, respectivamente. O tempo de vida da transição 4I13/2 → 4I15/2 (em 1530 nm) do Er3+ diminui com o aumento da concentração de Er3+, refletindo o quão importante é o processo não-radiativo associado a esta transição. A teoria de McCumber foi usada para calcular, a partir da seção de choque de absorção, a seção de choque da emissão estimulada da transição 4I13/2 → 4I15/2 do Er3+. Observamos e analisamos uma forte reabsorção da fluorescência em 1530 nm. Finalmente, discutimos a aplicabilidade dos vidros EDLP em dispositivos fotônicos.
Silva, Paulo Maria de Oliveira e. "Estudo dos efeitos da adiÃÃo de ZnO e Nb2O5 nas propriedades dielÃtricas da matriz cerÃmicas BaBi4Ti4O15 (BBT) e suas aplicaÃÃes em antenas." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10945.
Повний текст джерелаCom o rÃpido crescimento das indÃstrias de telecomunicaÃÃes criou-se uma forte necessidade por materiais cerÃmicos para aplicaÃÃes em micro-ondas. Devendo estes materiais apresentar alta permissividade dielÃtrica (εr), elevado fator de qualidade (Q), boa estabilidade tÃrmica (τf Â10 ppm/ÂC) e baixo custo. Com a invenÃÃo de telefones celulares portÃteis, o campo da comunicaÃÃo sem fio passou por um crescimento inovador nas Ãltimas dÃcadas. O sucesso da terceira geraÃÃo (3G) dos serviÃos de comunicaÃÃo de telefonia celular, motiva o desenvolvimento de banda larga de quarta geraÃÃo (4G) de telefones celulares e outros produtos e serviÃos sem fio, como por exemplo, o Bluetooth. Este trabalho consiste no desenvolvimento e caracterizaÃÃo da cerÃmica de titanato de bÃrio-bismuto (BaBi4Ti4O15) com adiÃÃo de Ãxido de niÃbio (Nb2O5) ou Ãxido de zinco (ZnO), visando a diminuiÃÃo da temperatura de sinterizaÃÃo e possivelmente melhorar a densificaÃÃo, e posteriormente, verificar as modificaÃÃes ocorridas nas propriedades do material, como por exemplo, o coeficiente de temperatura da frequÃncia ressonante (τf). As sÃries cerÃmicas foram produzidas usando a reaÃÃo no estado sÃlido, com o uso de moagem mecÃnica de alta energia e tratamento tÃrmico. A caracterizaÃÃo estrutural foi realizada com base na Microscopia EletrÃnica de Varredura (MEV) e Picnometria. As densidades relativas das amostras adicionadas com (ZnO) a de maior concentraÃÃo teve valor de 77% enquanto que o BBT puro o valor foi de 56%. As densidades relativas das amostras adicionadas com (Nb2O5) a de maior concentraÃÃo teve valor de 61% em relaÃÃo ao BBT puro. Foram realizados experimentos para avaliaÃÃo do comportamento elÃtrico e dielÃtrico das amostras, na faixa de Micro-ondas e RadiofrequÃncia (temperatura ambiente e com variaÃÃo de temperatura). Por fim, o material foi testado como uma DRA, e posteriormente os resultados obtidos foram simulados atravÃs do programa HFSS. As caracterÃsticas da DRA da cerÃmica pura sÃo 1,12dBi de ganho e 32,51% de eficiÃncia. A DRA que foi adicionada com 2% de (ZnO) apresentou ganho de 1,16dBi com 33,96% de eficiÃncia, enquanto a que foi adicionada com 5% de (Nb2O5) apresentou 1,41dBi de ganho com 42,21% de eficiÃncia.
With the rapid growth of the telecommunications industry created a strong need for ceramic materials for applications in microwave. These materials should exhibit high dielectric permittivity (εr), high quality factor (Q), good thermal stability (τf Â10 ppm/ÂC) and low cost. With the invention of mobile phones, the field of wireless communication has undergone a revolutionary growth in recent decades. The success of the third generation (3G) services in mobile communication, motivates the development of broadband fourth generation (4G) of mobile phones and other wireless products and services, such as Bluetooth. Nowadays it is well known the use of tablets, which are increasingly gaining market and encouraging the development of new technologies to improve the flow of information. This work involves the development and characterization of the barium bismuth titanate ceramic, (BaBi4Ti4O15) with addition of niobium oxide (Nb2O5) or zinc oxide (ZnO) in order to decrease the sintering temperature and possibly improve the densification and subsequently check the modifications on material properties, such as the temperature coefficient of resonant frequency (τf). The series ceramics were produced using the solid state reaction with the use of high energy mechanical milling and heat treatment. The structural characterization was performed based on Scanning Electron Microscopy (SEM) and Measurement by Pycnometer. The relative densities of the samples with added (ZnO) had the highest concentration value of 77% pure BBT while the value was 56%. The relative densities of the samples spiked with (Nb2O5) had the highest concentration value of 61% compared to pure BBT. Experiments were conducted to evaluate the electrical and dielectric behavior of the samples in the range of Microwave and Radio Frequency (temperature and temperature variation). Finally, the material was tested as a DRA, and then the results were simulated using the HFSS program. The characteristics of the pure ceramic DRA are 1,12dBi gain and 32,51% efficiency. The DRA added with 2% (ZnO ) showed 1.16dBi gain with 33,96% efficiency , while the one that was added with 5% (Nb2O5) showed gain of 1.41dBi with 42,21% efficiency.
Carvalho, Priscilla Ramos. "Estudo comparativo dos algoritmos hierárquicos de análise de agrupamentos em resultados experimentais." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-31102018-112210/.
Повний текст джерелаThe objective of this work was to study the hierarchical methods of cluster analysis (single linkage, complete linkage, average linkage, centroid and Ward with base in the Euclidean distance, Squared Euclidean distance, Manhattan and Mahalanobis) to identify which is the most appropriate in archaeological data set. It was used a data set provided by the Archaeometry Studies Group from IPEN CNEN/SP in which 146 samples of ceramic fragments from three archaeological sites analyzed by instrumental neutron activation analysis, being determined the mass fractions of 24 chemical elements: As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn. For the determination of the best method, it was evaluated the dendrograms together with value of the cophenetic correlation coefficient (CCC) obtained for each method. The average linkage method was more coherent in formation of the clusters, and with higher CCC values. Finally, a script with functions of the R statistical software was developed to calculate the CCC with aim to be a tool for researchers find the most appropriate method of cluster analysis for their data set.
Nobile, Cécile. "Phytodisponibilité du phosphore dans les sols agricoles de La Réunion fertilisés sur le long-terme avec des résidus organiques : la dose d’apport est-elle le seul déterminant à prendre en compte ?" Thesis, La Réunion, 2017. http://www.theses.fr/2017LARE0059/document.
Повний текст джерелаApplication of organic residues (OR) on agricultural soils could reduce the use of mineral phosphorus (P) fertilizers, but this implies to determine the efficiency of OR to meet crop requirements. We thus aimed to study mechanisms determining the effects of OR on P bioavailability to plants (phytoavailability). Our work was based on five field trials with decadal organic or mineral fertilization located in Réunion island, and on incubations and plant growth experiments under controlled conditions. Available inorganic P (Pi) and organic P (Po) was determined using extractions (water, Olsen), the diffusive gradients in thin films technique (DGT) and the isotopic dilution associated to anion exchange membranes (EAEM). Phytoavailable P was determined as the plant P uptake. Soil Pi sorption capacity was determined using sorption curves. For all soil types studied (andosol, andic cambisol, nitisol, and arenosol), RO increased mainly available Pi and had few effects on available Po, which suggests that mineralization of Po applied with RO does not limit Pi availability. Application of RO increased available Pi mainly by increasing soil pH and consequently by decreasing soil Pi sorption capacity. Phytoavailable P increased with soil available Pi, but decreased with increasing soil pH. Our work suggests that except the dose of P applied, effect of RO on P phytoavailability depends mainly on soil pH changes induced
ROSSI, LUBIANKA F. R. "Acoplamento entre os métodos diferencial e da teoria da perturbação para o cálculo dos coeficientes de sensibilidade em problemas de transmutação nuclear." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23594.
Повний текст джерелаMade available in DSpace on 2015-03-17T10:41:16Z (GMT). No. of bitstreams: 0
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
Salgado, Sérgio Ricardo Toledo. "Estudo dos parâmetros do decaimento do cloro residual em sistema de distribuição de água tratada considerando vazamento." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-15052008-205535/.
Повний текст джерелаThe use of chlorine as disinfectant in water supply systems has been a common practice adopted by the water industry. Introduced during the treatment process, chlorine participates in several reactions with compounds of organic and inorganic nature inside the pipes. Such reactions that occur in the bulk and the wall of the pipes are responsible for chlorine decay along the networks. Visualizing the modeling as an efficient tool to manage the chlorine residual in water distribution systems, many studies have been conducted and reported by the literature, assuming that the chlorine decay effects can be well represented by the decay coefficients kb and kw. However, the determination of values for theses parameters is not an easy task, due to the complexity of the focused systems in terms of pipe materials and water supply sources diversity (surface water and groundwater). In Brazil, instead of recent legislation stating more strict limits for chlorine in drinking water (after disinfection, chlorine concentration has to observe the minimum concentration of 0.5 mg/L, being the minimum accepted level in the distribution system of 0.2 mg/L and the maximum of 2.0 mg/L), few studies focus on the evaluation of the decay parameters. This research reports the application of an inverse model built to determine the order for chlorine decay model and the global and/or local values for kb and kw. It is codified with the support of EPANET 2 (Toolkit) simulator and technology of genetic algorithms as optimization tool, which is implemented by using the GAlib C++ library. The studies were conducted on two real water distribution systems considering both global and specific quality parameters. A hypothetical network with three sources of chlorine was studied too, admitting leakage as pressure function. This system permitted both calibration and validation of the model as well as the evaluation of hydraulic calibration influence on the water quality results.
Freitas, Francisco NÃlio Costa. "Adequabilidade das CondiÃÃes de LaminaÃÃo de um AÃo Baixo-Carbono à Estampagem Profunda." Universidade Federal do CearÃ, 2003. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7324.
Повний текст джерелаDependendo da direÃÃo em que sÃo medidas, algumas propriedades dos materiais policristalinos se apresentam diferenciadas. Isso se deve a existÃncia de textura, ou seja, direÃÃes preferenciais dos cristais no material. Esta caracterÃstica pode ser decorrente da solidificaÃÃo de um processo de deformaÃÃo plÃstica ou de um tratamento tÃrmico. A textura em materiais metÃlicos influencia nas propriedades dos mesmos tanto de uma maneira benÃfica quanto malÃfica. Na estampagem de um disco para fabricaÃÃo de um copo usado em armazenagem de refrigerantes tanto pode se destacar o efeito malÃfico, que seria a formaÃÃo de orelhas e o afinamento das regiÃes laterais adjacentes ao fundo do copo, como o efeito benÃfico, que seria o aumento da resistÃncia na direÃÃo perpendicular ao plano da chapa minimizando a possibilidade de ruptura pela reduÃÃo da espessura causada pelo processo de estampagem. Neste trabalho foi feito um estudo da relaÃÃo entre a textura cristalogrÃfica, os coeficientes de anisotropia e o grau de estampabilidade para o caso de um aÃo baixo-carbono, cuja principal aplicaÃÃo à na fabricaÃÃo de botijÃes para gÃs de cozinha, nas condiÃÃes de laminaÃÃo em temperaturas entre 600ÂC e 900ÂC. Os resultados foram comparados com os de um aÃo com baixÃssimo teor de carbono utilizado na estampagem profunda de latas para armazenagem de refrigerantes. A textura cristalogrÃfica foi determinada a partir das funÃÃes de distribuiÃÃo de orientaÃÃo cristalogrÃfica calculadas a partir de 3 figuras de pÃlos obtidas por difraÃÃo de raios-x. Os coeficientes de anisotropia mÃdia (rm) e planar (r) foram determinados a partir dos coeficientes de Lankford na direÃÃo de laminaÃÃo, a 45o desta e na direÃÃo transversal a mesma. O grau de estampabilidade foi obtido por meio de ensaios de embutimento Erichsen modificado, que relaciona a profundidade de estampagem com a espessura da chapa. As anÃlises de textura nos aÃos laminados em temperaturas entre 600ÂC e 900ÂC, apresentaram resultados compatÃveis com os de um aÃo usado na estampagem profunda de latas para armazenagem de refrigerantes. Os coeficientes de anisotropia mÃdia (rm) e planar (r), apresentaram valores satisfatÃrios de acordo com a exigÃncia para a mesma aplicaÃÃo. O grau de estampabilidade da maioria das amostras de chapas de aÃo laminadas em temperaturas entre 600ÂC e 900ÂC, mostrou-se adequado para a fabricaÃÃo das latas que servem como recipiente de armazenamento de refrigerantes.
Depending on which direction are measured, some properties of polycrystalline materials are presented differentiated. This is due to the existence of texture, or preferential directions of the crystals in the material. This feature may be due to solidification of a process of plastic deformation and heat treatment. The texture of metallic materials influences the properties of them both in a beneficial way as evil. In the printing of a hard to manufacture a glass of soda used in storage can either highlight the harmful effect, which would be the formation of ears and thinning of the lateral regions adjacent to the bottom of the glass, as the beneficial effect, which would be increased resistance in the direction perpendicular to the plane of the plate while minimizing the possibility of rupture by the thickness reduction caused by the embossing process. This work was used to study the relationship between the crystallographic texture, and anisotropy coefficients degree of drawability to the case of a low carbon steel, which is mainly used in the manufacture of bottles for cooking gas under the conditions of lamination temperatures between 600 Â C and 900 Â C. The results were compared with those of a steel with ultra low carbon used in deep drawing cans for storing soft drinks. The crystal texture was determined from the distribution functions of the crystallographic orientation calculated from the three figures obtained by poles x-ray diffraction. The average coefficients of anisotropy (rm) and planar ( r) were determined from the Lankford coefficients in the rolling direction, and the 45th of the same in the transverse direction. The degree of drawability was obtained by testing Erichsen cupping modified relating the depth of embossing to the thickness of the plate. The analysis of texture in rolled steels at temperatures between 600 Â C and 900 Â C showed results consistent with those of steel used in deep drawing of cans for storage of refrigerants. The average coefficients of anisotropy (rm) and planar ( r) values were satisfactory according to the requirement for the same application. The degree of drawability of most samples rolled steel sheet at temperatures between 600 Â C and 900 Â C, was suitable for the manufacture of cans which serve as storage container for soft drinks.
Depending on which direction are measured, some properties of polycrystalline materials are presented differentiated. This is due to the existence of texture, or preferential directions of the crystals in the material. This feature may be due to solidification of a process of plastic deformation and heat treatment. The texture of metallic materials influences the properties of them both in a beneficial way as evil. In the printing of a hard to manufacture a glass of soda used in storage can either highlight the harmful effect, which would be the formation of ears and thinning of the lateral regions adjacent to the bottom of the glass, as the beneficial effect, which would be increased resistance in the direction perpendicular to the plane of the plate while minimizing the possibility of rupture by the thickness reduction caused by the embossing process. This work was used to study the relationship between the crystallographic texture, and anisotropy coefficients degree of drawability to the case of a low carbon steel, which is mainly used in the manufacture of bottles for cooking gas under the conditions of lamination temperatures between 600 Â C and 900 Â C. The results were compared with those of a steel with ultra low carbon used in deep drawing cans for storing soft drinks. The crystal texture was determined from the distribution functions of the crystallographic orientation calculated from the three figures obtained by poles x-ray diffraction. The average coefficients of anisotropy (rm) and planar ( r) were determined from the Lankford coefficients in the rolling direction, and the 45th of the same in the transverse direction. The degree of drawability was obtained by testing Erichsen cupping modified relating the depth of embossing to the thickness of the plate. The analysis of texture in rolled steels at temperatures between 600 Â C and 900 Â C showed results consistent with those of steel used in deep drawing of cans for storage of refrigerants. The average coefficients of anisotropy (rm) and planar ( r) values were satisfactory according to the requirement for the same application. The degree of drawability of most samples rolled steel sheet at temperatures between 600 Â C and 900 Â C, was suitable for the manufacture of cans which serve as storage container for soft drinks.
Silva, Cristiane Arpino. "Comportamento dos perfis de cloreto em tetrápodes localizados nos molhes da Barra. (Rio Grande – RS –. Brasil)." reponame:Repositório Institucional da FURG, 2010. http://repositorio.furg.br/handle/1/3490.
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Made available in DSpace on 2013-06-10T18:28:50Z (GMT). No. of bitstreams: 1 Comportamento Dos Perfis De Cloreto Em Tetrápodes Localizados Nos Molhes Da Barra. (Rio Grande – RS –. Brasil)..pdf: 8213108 bytes, checksum: 3de71990a8d41cc4d48f12c77b892ecb (MD5) Previous issue date: 2010
A vida útil de estruturas de concreto armado tem sido motivo de preocupação entre os diversos pesquisadores da área. Com o objetivo de melhor compreender o comportamento de uma estrutura de concreto armado, exposta ao ambiente marítimo, foi realizada uma avaliação dos tetrápodes dos molhes da Barra do Rio Grande à 5 anos de exposição (Guimarães, 2003) com a retirada de amostras e o traçado dos perfis de cloreto. Após essa avaliação, fora identificado um alto teor de cloretos no interior dos tetrápodes, que atribui-se a uma possível contaminação desses elementos durante a sua confecção. O presente trabalho teve com o objetivo avaliar o desempenho dos tetrápodes quanto a penetração de íons cloreto ao longo do tempo, e para tal foi realizada uma comparação entre os perfis de cloreto aos 5 anos e aos 9,5 anos. Com as equações de Cranck (1975) foi obtido um modelo no qual se considerou a variação da concentração de cloretos na superfície (Cs), pois esse parâmetro aumentou significativamente dos 5 para 9,5 anos. O referido modelo apresentou bons resultados, pois os perfis estimados demonstraram semelhança com os perfis de medição de cloreto dos tetrápodes, principalmente na idade de 9,5 anos e com o uso de keq, demonstrando a importância de sua aplicabilidade na prática. A partir do coeficiente de difusão estimado aos 9,5 anos, obteve-se os perfis de cloreto para Cs fixo de 0,588 %, aos 50 anos, aos 100 anos e aos 200 anos. De posse dos coeficientes de difusão aos 9,5 anos e com o uso de k e keq, foi estimado o grau de saturação, a partir de uma comparação com o estudo de Rodrigues (2009). Para confirmar o alto GS estimado para o ponto MLOI, foi realizado ensaio de GS dia nos tetrápodes. Os resultados foram satisfatórios e apresentaram coerência com as estimativas. Enfim, os ambientes dos tetrápodes demonstraram grande agressividade com altos teores de cloreto em profundidades consideráveis. Portanto, para o caso de uma estrutura de concreto armado, inserida em ambiente semelhante aos tetrápodes, não só as recomendações da NBR 6118/2003 são suficientes para garantir a durabilidade da estrutura, principalmente no que se refere ao cobrimento do concreto, devendo principalmente ser considerado o tipo de cimento a ser utilizado.
The useful life of structures made of reinforced concrete has been a matter of concern to researchers in this field. An evaluation of the tetrapods at the jetties located in Rio Grande, RS, was carried out after their five-year exposure to a marine environment (Guimarães, 2003)with the aim of understanding the behavior of a structure made of reinforced concrete under such conditions. Samples were collected and the chloride profiles were executed. After this evaluation, a high concentration of chloride was found in the interior of the tetrapods; this fact may be attributed to contamination during their manufacturing. This paper aims at evaluating the behavior of tetrapods regarding the penetration of chloride ions throughout some time. Therefore, a comparison between the chloride profiles at the age of 5 and at the age of 9.5 was made. Cranck’s equations (1975) led to a model in which the variation of the surface chloride concentration (CS) was taken into account, since this parameter has significantly increased from 5 year-old tetrapods to 9.5 year-old ones. This model showed good results: the estimated profiles were similar to the measurement profiles of the chloride of the tetrapods, mainly at 9.5 and with the use of keq. This is an evidence of the importance of its practical applicability. Based on the diffusion coefficient which was estimated for 9.5 year-old tetrapods, 0.588% was obtained as a fixed profile of CS at 50, 100 and 200 years old. Based on the diffusion coefficients at 9.5 and with the use of k and keq, the saturation degree (SD) was estimated after a comparison with Rodrigues’ study (2009). To confirm the high SD which was estimated for the MOIL point, a SDday test was carried out with the tetrapods. Results were satisfactory and coherent with the estimates. Finally, the environment, in which the tetrapods were, showed a high level of aggressiveness with high concentration of chloride at considerable depths. Therefore, in the case of a structure made of reinforced concrete which is an environment that is similar to the one in which tetrapods are, the NBR 6118/2003 recommendations alone are not enough to assure the durability of the structure, mainly regarding the concrete cover, i.e., the type of cement must also be chosen accordingly.
Kotze, Izak Aldert. "Self-association of [PtII(1,10-Phenanthroline)(N-pyrrolidyl-N-(2,2-dimethyl-propanoyl)thiourea)]+ and non-covalent outer-sphere complex formation with fluoranthene through cation-π interactions : a high resolution 1H and DOSY NMR study". Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1796.
Повний текст джерелаLopes, Carlos Alberto de Abreu. "Desenvolvimento de um modelo hedónico de avaliação de imóveis habitacionais para o concelho de Cascais." Master's thesis, Instituto Superior de Economia e Gestão, 2014. http://hdl.handle.net/10400.5/7977.
Повний текст джерелаEste estudo utiliza métodos de regressão linear com o intuito de estimar equações hedónicas que permitam construir uma ferramenta para determinar o valor esperado dos imóveis. Os dados da pesquisa são utilizados para investigar a relação entre os preços declarados dos imóveis residenciais e os seus atributos, no contexto do mercado imobiliário do Concelho de Cascais. Este conjunto de dados inclui algumas características das habitações, como a área bruta privativa, número de assoalhadas, lugares de estacionamento, varandas, terraços, variáveis de localização, etc. Devido à importância que o factor localização tem no valor dos imóveis, procurou-se analisar se o Coeficiente de Localização do Código do Imposto Municipal sobre Imóveis (CIMI) seria uma variável explicativa do valor esperado dos imóveis, o que foi comprovado pelos modelos estimados. Contudo, o estudo não foi totalmente conclusivo sobre o efeito da proximidade de algumas amenidades no valor dos imóveis, excepto no caso das praias, zonas comerciais e zonas de lazer. Adicionalmente concluiu-se que os Golden Visa têm um efeito positivo e estatisticamente significativo no valor dos imóveis, sendo no entanto necessário interpretar este resultado com cautela dada a escassez de observações e o período temporal analisado.
This study uses linear regression methods in order to estimate hedonic equations for developing a tool to determine the expected value of the property. The survey data are used to investigate the relationship between the prices of residential properties declared by the buyers and their attributes, regarding the housing market of Cascais. This data set includes some characteristics of households, such as private gross floor area, number of rooms, parking spaces, balconies, terraces, location, etc. Given the importance that location has on property values, it was examined whether the location coefficient of Código do Imposto Municipal sobre Imóveis (CIMI) would be an explanatory variable for the expected value of the property, which has been confirmed by the estimated models. However, the study was not entirely conclusive about the effect of proximity of some amenities in the real estate market, except for beaches, shopping and leisure areas. Additionally it was found that the Golden Visa have a positive and statistically significant effect on the value of the property. However it is necessary to read into this result with caution given the limited observations and the time period analyzed.
Santos, Clenilton Costa dos. "Propriedades Ãpticas dos vidros Er3+:PbPO4." Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=4874.
Повний текст джерелаNeste trabalho utilizamos vÃrias tÃcnicas para investigar as propriedades Ãpticas dos vidros fosfato de chumbo (PbPO4) com concentraÃÃes moderadamente altas de Ãons de Ãrbio (Er3+), EDLP. Medimos a susceptibilidade de terceira ordem, χ3, e a dispersÃo do Ãndice de refraÃÃo linear, n0(λ), dos vidros EDLP na regiÃo de comprimento de onda entre 400 e 1940 nm, por meio da tÃcnica de Franjas de Maker. A partir do valor de χ3, calculamos o Ãndice de refraÃÃo nÃo-linear, n2, cujo valor à cerca de cinco vezes maior que o da sÃlica (SiO2). TambÃm obtivemos os valores de n2 dos vidros EDLP, atravÃs da tÃcnica de varredura Z para vÃrios comprimentos de onda. A diferenÃa entre os valores obtidos pelas duas tÃcnicas foi de 15%. Realizamos medidas de absorÃÃo Ãptica, cujos dados foram utilizados para calcular os parÃmetros fenomenolÃgicos Ωλ da teoria de Judd-Ofelt. Observamos que Ω4 e Ω6 permanecem praticamente constante com o aumento da concentraÃÃo de Er3+, ao passo que Ω2 diminui. Excitando as amostras em 800 nm foi possÃvel verificar emissÃes no verde, vermelho e infravermelho, centradas em 530, 550, 660 e 1530 nm, respectivamente. O tempo de vida da transiÃÃo 4I13/2 → 4I15/2 (em 1530 nm) do Er3+ diminui com o aumento da concentraÃÃo de Er3+, refletindo o quÃo importante à o processo nÃo-radiativo associado a esta transiÃÃo. A teoria de McCumber foi usada para calcular, a partir da seÃÃo de choque de absorÃÃo, a seÃÃo de choque da emissÃo estimulada da transiÃÃo 4I13/2 → 4I15/2 do Er3+. Observamos e analisamos uma forte reabsorÃÃo da fluorescÃncia em 1530 nm. Finalmente, discutimos a aplicabilidade dos vidros EDLP em dispositivos fotÃnicos.
In this work we employ several techniques to investigate the optical properties of moderately high Er3+-doped lead phosphate (EDLP) glasses. The third-order optical susceptibility, χ3, and dispersion of the linear refractive index, n0(λ), of Er3+:PbPO4 were measured in the wavelength range between 400 and 1940 nm by using the spectrally resolved femtosecond Maker fringes technique. The nonlinear refractive index, n2, obtained from the third-order susceptibility was found to be five times higher than that of silica. For comparison purposes, the Z-scan technique was also employed to obtain the values of n2 of EDLP at several wavelengths, and the values obtained using the two techniques agree to within 15%. From the data obtained by absorption measurements, the Judd-Ofelt theory was employed to calculate the intensity-dependent parameters Ωλ (λ = 2, 4, and 6). We observed that increasing Er3+ content, Ω4 and Ω6 remain constant, while Ω2 decreases. Green, red, and infrared emissions centered at 530, 550, 660, and 1530 nm were observed under excitation at 800 nm. The lifetime of the Er3+: 4I13/2 → 4I15/2 (1530 nm) transition decreases with increasing Er3+ content, reflecting how significant the non-radiative process associated with this transition is. The McCumber theory was used to calculate, from absorption cross-section, the stimulated emission cross-section of the Er3+: 4I13/2 → 4I15/2 transition. A strong re-absorption of the fluorescence at 1530 nm was also observed and analyzed. Finally, we discuss the potential use of Er3+:PbPO4 glasses in photonics devices.
Porto, Eduardo Figueiredo. "Verificação dos valores dos coeficientes de convecção do ar no exterior de edifícios no estado da Paraíba." Universidade Federal da Paraíba, 2007. http://tede.biblioteca.ufpb.br:8080/handle/tede/9113.
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This research investigated and analysed the characteristics and peculiarities of wind flowing that take place in the state of Paraiba in order to verify the local values for the air coefficients of external convection (hc’s), based in non-dimensional numbers like Prandlt, Reynolds and Nusselt, and empirical correlations as suggested by Hilpert. These correlations are widely used and the results demonstrate that the verified values significantly differ from the ones currently recommended by the Brazilian norms concerning the thermal performance of buildings and the basic parameters of projects for central air-conditioners. The results highlighted the need to review these coefficients and take into consideration the interrelationship between the standards of local ventilation and construction regulations when calculating the thermal conditioning of buildings in order to minimize environmental impact and improve energy performance of buildings, which will reduce costs.
Este trabalho investigou e analisou as características e as condições de escoamento dos ventos que ocorrem no estado da Paraíba, a fim de determinar valores locais para os coeficientes de convecção do ar externo (hc’s), com base nos números adimensionais de Prandlt, Reynolds e Nusselt, e correlações empíricas com as sugeridas por Hilpert, que são largamente utilizadas, cujos resultados demonstraram que os valores verificados diferem significativamente dos valores atualmente recomendados palas Normas Brasileiras referentes ao desempenho térmico de edificações, e aos parâmetros básicos de projeto de centrais de ar-condicionado, conduzindo à necessidade de se reverem tais coeficientes e considerarem as inter-relações entre o padrão de ventilação local e o de ocupação do solo, quando do cálculo de acondicionamento térmico de edifícios, para se minimizar os impactos ambientais, otimizar o desempenho energético de edificações, aumentando a economia de energia reduzindo custos.
Coelho, Welington Ricardo. "Análise do fenômeno de cavitação em bomba centrífuga /." Ilha Solteira : [s.n.], 2006. http://hdl.handle.net/11449/88879.
Повний текст джерелаBanca: Jose Luiz Gasche
Banca: Paulo Gilberto de Paula Toro
Resumo: Cavitação em bombas centrífugas é a formação de bolhas de vapor do fluido bombeado na região de sucção do equipamento. As bolhas de vapor formadas em algum local do escoamento, em geral na região de sucção da bomba, entrarão posteriormente em colapso. Este fenômeno é importante cientificamente, tecnicamente e economicamente. Cientificamente é interessante, pois envolve o escoamento de um fluido em estado líquido, simultaneamente ocorre a formação de bolhas de vapor, que também escoam juntamente ao fluido líquido. O processo de vaporização e condensação de um fluido é complexo, pois envolve mudança de fase, um fenômeno térmico não linear. Tecnicamente, é importante porque quando o escoamento se dá com cavitação os parâmetros hidrodinâmicos do escoamento bem como da bomba, em geral, são fortemente alterados na direção termodinâmica de maior produção de irreversibilidades. Economicamente, é custoso porque a cavitação, em geral, leva a perda de eficiência termodinâmica dos processos e em conseqüência haverá maior custo na produção de um dado bem, diminuindo a eficiência econômica e a competitividade da empresa. O escoamento com cavitação na sucção de bombas apresenta três aspectos danosos principais: cavitação pulsante com baixa vazão; cavitação não pulsante com baixa altura útil; e erosão cavitacional. A cavitação pulsante é caracterizada por grande formação de bolhas de forma transitória com baixa freqüência e grande amplitude, gerando forças vibratórias importantes no sistema de bombeamento. A cavitação pulsante também causa colapso do fluxo de massa do fluido bombeado com valores que vão do fluxo normal da instalação até valores quase nulos, transitoriamente. Na cavitação pulsante a erosão cavitacional e a queda na altura útil são pequenas... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Cavitation in centrifugal pumps is the development of vapor bubbles from the pumped liquid into equipment suction region. Vapor bubbles developed somewhere in the flow, generally in the pump suction, will afterwards along the flow to collapse. This phenomenon is scientifically, technically and economically important. Scientifically, it is interesting because involves the flow of a fluid on liquid state, and simultaneously happens vapor bubbles development that also flow together the liquid fluid. Fluid vaporization and condensation processes are complex because involves phase change, a non-linear thermal phenomenon. Technically, it is important because when the flow happens with cavitation the flow and pump hydrodynamic parameters, generally, are strongly modified toward bigger thermodynamic irreversibility production. Economically, it is expensive because cavitation, generally, leads to thermodynamic process efficiency loss, and consequently it will have bigger costs for production of a given good, then decreasing economic efficiency and company competitiveness. Flow with cavitation in the pump suction presents three main devastating aspects: surging cavitation with low flow rate; steady cavitation with low total head; and cavitational erosion. Surging cavitation is characterized by unsteady, low frequency and high amplitude, intense bubbles development, producing strong vibration forces into the pumping system. Surging cavitation also causes the collapse of pumped fluid mass flow rate with values that goes from the normal flow to values that almost reach the zero flow, unsteadily. In surging cavitation, the cavitational erosion and the breakdown in total head are small. In steady cavitation the mass flow rate, and even the flow rate... (Complete abstract click electronic access below)
Mestre
Fragelli, Renan Luis [UNESP]. "Análise da capacidade de refrigeração dos nanofluidos de prata e hematita com enfoque na aplicação prática em porta-ferramentas refrigerado internamente." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150017.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Este trabalho surgiu a partir da necessidade de produzir avanços em projeto que trata do desenvolvimento de um porta-ferramentas refrigerado internamente através de um fluido em mudança de fase e, na tentativa de minimizar a alta temperatura na ferramenta de corte através desse sistema de circulação. A utilização de nanofluidos surgiu como uma alternativa para a otimização da transferência térmica entre fluido e ferramenta de corte. A pesquisa consiste em avaliar a influência da adição de nanopartículas de prata numa solução de etilenoglicol e água deionizada, e também, da adição de nanopartículas de hematita (Fe2O3) no fluido refrigerante R141b. Em ambos os casos, as nanopartículas possuíam formato esférico, diâmetro médio de 30nm e foram avaliadas em concentrações. Além disso, as duas soluções foram submetidas a um campo elétrico na região de transferência térmica para analisar a influência do efeito eletrohidrodinâmico e, por fim, considerando as propriedades magnéticas da hematita, este nanofluido foi testado sob influência de um campo magnético. Os testes mostraram que as nanopartículas realmente influenciaram as propriedades dos fluidos e, por consequência, a quantidade de calor transferido. O nanofluido Ag/ETG+H2O(l) (0,023 vol%) resultou num incremento de 11% no valor do coeficiente de transferência térmica convectivo (h) quando sujeito ao campo elétrico. Para o caso do nanofluido Fe2O3/R141b, o valor de h aumentou em 30,3%, porém, quando sob efeito do campo magnético ou elétrico, o coeficiente foi prejudicado, resultando num valor menor que o do controle. Ao final, tem-se a proposta de um possível modelo desse porta-ferramentas.
This work arose from the need to produce advances in design development of an internally cooled toolholder through a phase change fluid. In order to minimize the high temperature in the cutting tool by this circulation system, using nanofluids emerged as an alternative to optimize heat transfer between the fluid and the cutting tool. The research consists in evaluate the influence of addition of silver nanoparticles in an ethylene glycol and deionized water solution, and also the addition of hematite nanoparticles (Fe2O3) in the refrigerant R141b. In both cases, nanoparticles had spherical shape, diameter of 30nm, and they were evaluated in different concentrations. Moreover, both nanofluids were subjected to an electric field in the heat transfer region to evaluate the influence of electrohydrodynamic effect and, finally, considering the magnetic properties of hematite, this nanofluid was tested under the influence of a magnetic field. The tests have shown that the nanoparticles really influence the properties of the fluids and, therefore, the amount of heat transferred. The nanofluid Ag/ETG+H2O(l) also presented a positive influence of the electric field, further enhancing the value of the convective heat transfer coefficient (h) in 11% (0,039 vol%). In the case of Fe2O3/R141b nanofluid, the h value increased 30.3%. However, when the nanofluid was under magnetic or electric effect, the value of h was deteriorated, resulting in a lesser value than the control. As conclusion, a new toolholder prototype is presented.