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The study of frequency modulation for dual-band solidly mounted resonators and filtersWu, Tong-ting 26 July 2007 (has links)
ABSTRAT
In this thesis, we focused on the fabrication and frequency-modulation of £f/4 mode dual-band solidly mounted resonators and filters. To accomplish the Bragg reflector, the RF/DC magnetron sputtering system with dual targets is adopted to deposit alternating layers of quarter-wavelength Mo and SiO2 thin films. We tune the fabrication parameters in accordance with the AFM measurement and achieve a low roughness of 2.9nm on a nine-layer reflector. The piezoelectric layer, aluminum nitride (AlN) thin films, is deposited on the Bragg reflector by means of reactive RF magnetron sputtering. We alter the distance between substrate and target is altered to deposit AlN with various c-axis tilting angle which results in longitudinal and shear acoustic waves at the same time. Furthermore, we use mass loading effect to modulate the resonance frequency and fabricate £k- ladder type filters.
In various numbers of reflector layers, the optimum frequency response is obtained with return loss of -26dB, in a SMR on a 3.5 pair reflector. To investigate the relationship between longitudinal and shear resonance in different resonance frequency, we alter the c-axis tilting angle of AlN as well as various mass loading on the SMRs. Based on the experimental results, the ratio of longitudinal to shear resonance frequency remains a constant value despite various c-axis tilting angle of AlN and mass loading on the SMRs. In addition, the electromechanical coupling coefficient, Kt2, of shear resonance raises with the increase of c-axis tilting angle of AlN.
Finally,we have successfully fabricated SMRs with frequency modulataion of 3,899.68 Hz-cm2/ng and £k-ladder type filters with 26 MHz bandwidth.
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Hiroshima survivors exposed to very low doses of A-bomb primary radiation showed a high risk for cancersWatanabe, Tomoyuki, Miyao, Masaru, Honda, Ryumon, Yamada, Yuichi January 2008 (has links)
No description available.
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The Resonance Characteristics of Solidly Mounted Resonators with 1/4 and 1/2 £f Mode ConfigurationsLi, Sin-Ren 26 August 2008 (has links)
In this thesis, we emphasized on fabrication and anlysis of 1/4 and 1/2 £f mode solidly mounted resonators. First, the reactive RF magnetron sputter used to deposit the highly c-axis-oriented aluminum nitride (AlN) piezoelectric films under different parameters. The various c-axis tilt angle also used it by altering the distance between substrate and target to investigate the characteristics.
To accomplish the two modes of different pairs of Bragg reflector, the RF/DC sputter system is adopted alternating layers of quarter-wavelength Mo and SiO2 thin films by different sequence. Finally, depositing the highly c-axis-oriented AlN on reflectors to complete the 1/4 and 1/2 £f mode SMR.
The AlN thin film achieve a very low roughness of 1.783nm under AFM measurement, the FWHM of XRD(002) peak is 3.507¢Xand SEM images also exhibit a highly oriented c-axis structure.
The optimum frequency responses of 1/2 £f mode SMR is obtained with return loss of -57.23dB at 4 pairs reflectors,which for 1/4 £f mode SMR is -30.68dB at 3 pairs. The maximum electromechanical coupling coefficient (Kt2) of 1/2 £f mode SMR is 7.88%, but the quality factor (Q) of 1/4 £f mode SMR is 4231.29.
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A Multi-Modular Neutronically Coupled Power Generation SystemPatel, Vishal 2012 May 1900 (has links)
The High Temperature Integrated Multi-Modular Thermal Reactor is a small modular reactor that uses an enhanced conductivity BeO-UO2 fuel with supercritical CO2 coolant to drive turbo-machinery in a direct Brayton cycle. The core consists of several self-contained pressurized modules, each containing fuel elements in pressurized channels surrounded by a graphite moderator, and Brayton cycle turbo-machinery. Each module is subcritical by itself, and when several modules are brought into proximity of one another, a single critical core is formed.
The multi-modular approach and use of BeO-UO2 fuel with graphite moderator and supercritical CO2 coolant leads to an inherently safe system capable of high efficiency operation. The pressure channel design and multi-modular approach eliminates engineering challenges associated with large pressure vessels. The subcriticality of the modules ensures inherent safety during construction, transportation, and after decommissioning.
Serpent, a continuous-energy Monte-Carlo reactor physics burnup calculation code, was used to develop a critical configuration of the subcritical modules using UO2 fuel enriched with 5 wt% 235U with a 5 wt% BeO additive. The core lifetime was found to be 14.6 years operating at 10 MWth, though the U enrichment and power can be altered to achieve desired core lifetimes. Negative fuel and moderator temperature coefficients of reactivity were found that could maintain safety during operation.
The multi-modular design was found to be beneficial compared to a core with all fuel elements in one module. Batch battery type refueling was found to be beneficial and the feasibility of controlling the reactor was demonstrated through the use of control shells that surround each module.
The HT-IMMTR design is an inherently safe, highly efficient, economically competitive, and most important, feasible reactor design that takes advantage of proven technologies to facilitate the demonstration of a successful commercial deployment.
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Fabrication of Piezoelectric and Reflecting Layers for Solidly Mounted Resonator (SMR)Wei, Ching-Liang 21 July 2005 (has links)
In this study, AlN films are deposited using reactive RF magnetron sputter on various bottom metals, such as Mo, Al and Pt. The orientation of piezoelectric AlN thin films on different bottom electrode materials are investigated. Moreover, the acoustic Bragg reflectors deposited by DC magnetron sputter are composed of alternating layers of high and low acoustic impedance materials. To improve the performance of the reflectors, rapid thermal anneal and deposition process control over roughness of the thin film are also investigated.
The resonance characteristics are improved obviously by deposition process control over thin films. The roughness control is the key factor of good frequency responses of SMR. In addition, the more layer of the reflectors the better the frequency response we obtained.
The frequency responses of SMR are slightly improved by rapid thermal annealing procsess. Although defects in the thin films would be eliminated, nevertheless the thin film roughness became worse after annealing. This phenomenon would limit the improvement of frequency responses.
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A Comparison Between Foam Rolling and Dynamic Stretch on Throwing Velocity and Accuracy Among Male Handball PlayersIvarsson, Tommy January 2014 (has links)
The monotonous and strenuous shoulder moving pattern during throwing may result in microtrauma and fibrous adhesions between the layers of fascia among athletes. In the last decade, self myofascial release (SMR) has gained good reputation as a way to treat these adhesions. However, there is limited data demonstrating the effects on upper body performance among athletes. PURPOSE: The purpose was to examine the effects from an acute bout of upper body SMR or from dynamic stretch (DS), on shoulder range of motion (ROM), throwing velocity and throwing accuracy. Also to examine correlations between shoulder ROM and throwing velocity/accuracy and between playing experience (PE) and changes in throwing velocity/accuracy and ROM. METHODS: 20 elite male handball players (age 20 ± 5 years, weight 84 ± 9 kg) were included in the study. The study had an experimental cross-over design in which participants first performed baseline measures. They also performed SMR and DS in two different trials. The trials were supervised and separated by 14 days. During SMR, the athletes performed a series of foam rolling exercises during two minutes for the muscles surrounding the shoulder joint. The same muscles were stretched for two minutes during the DS trial. Directly after foam rolling and DS, shoulder ROM, throwing velocity and throwing accuracy were measured using a gravity reference goniometer, radar gun and a high speed videocamera. ANOVA with repeated measures and t-tests were used to analyze differences between and within groups. RESULTS: There were no statistically significant differences in either shoulder ROM, throwing velocity or throwing accuracy between the three trials. There was a moderate correlation between shoulder extension and mean accuracy (r = 0.62; p = 0.004) after DS. When dividing the group into high and low experienced players, among the players in the PE-low group, the most experienced players elicited the greatest increase in peak throwing velocity after DS (r = 0.58; p = 0.10). Change in peak accuracy showed moderate but conflicting correlations after SMR (r = -0.53; p = 0.09) and DS (r = 0.50; p = 0.11) for the players in the PE-high group, indicating a better result after SMR. CONCLUSION: An acute bout of upperbody SMR does not affect ROM and does not improve throwing velocity or throwing accuracy compared to baseline or DS among elite male handball players. Nor could any correlation between ROM and throwing velocity or throwing accuracy be observed. The associations between PE and throwing performance was inconclusive. Further studies is needed to define if PE should be taken into consideration when using SMR or DS in order to improve throwing performance.
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The acute effect of a foam rolling and a dynamic stretch warm-up routine on jumping performanceÅrneby, Henrik January 2014 (has links)
Background: Self-myofascial release is widely used by athletes but the scientific evidence of its supposedly positive effects is limited. This study was conducted to investigate the effects of foam rolling as a warm-up routine in comparison with a dynamic stretching routine and how it may affect the jumping performance among subjects familiar with weight training. Aim: The aim of this study was to investigate the acute effect of foam rolling vs. a standardized dynamic stretch warm-up routine on jumping performance. Method: Twelve subjects, mean (SD) age 25.1 (± 3.0) years, participated in a randomized, controlled, crossover study. All subjects completed a standardized foam rolling (FR) and a dynamic stretch (DS) warm-up routine on separate days of testing. Squat jump (SJ), counter movement jump (CMJ) and loaded counter movement jump (L-CMJ) all performed bilaterally and unilaterally were conducted to investigate the acute effect of the two warm-up routines. A dependent T-test was used to investigate differences between the warm-up routines. Results: A statistical significant difference in favor of the DS was found for SJ performed bilaterally among males (p = 0.009). The mean (SD) jumping height for SJ FR was 35.6 (± 4.7) cm and for SJ DS 37.9 (± 5.2) cm. The male group also improved more in L-CMJ performed on the right leg with an external load of 54kg after DS compared to FR. No other statistical significant differences were found between the two interventions. A near statistical significant difference was found for SJ performed bilaterally for the total sample (p = 0.057) also in favor of the DS. The mean (SD) jumping height for SJ FR was 29.3 (± 8.7) cm and for SJ DS 30.5 (± 9.9) cm. Conclusion: Findings from this study supports a dynamic stretch warm-up routine prior to performing high intensity bilateral plyometrics instead of a foam rolling warm-up routine. However the data was inconsistent and more research with larger sample sizes is needed to further investigate the possible effects of foam rolling as a warm-up routine on jumping performance performed both bilaterally and unilaterally.
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Identificação de danos em fachadas de edificações por meio de imagens panorâmicas geradas por plataforma robótica fotográfica / Identification of damage on facades of buildings by panoramic images generated by robotics photographic platformCosta, Márcia Silvano 30 July 2014 (has links)
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2014. / Submitted by Ana Cristina Barbosa da Silva (annabds@hotmail.com) on 2014-12-09T18:45:37Z
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2014_MarciaSilvanoCosta.pdf: 45538360 bytes, checksum: d48ec12523a5b90b274622305e239ad6 (MD5) / Este trabalho trata do desenvolvimento do método de inspeção de danos em superfícies externas de fachadas de edificações, por meio da aplicação de um Sistema de Monitoramento Remoto (SMR) com base na Fotogrametria Digital. Esta técnica é fundamentada na geração de imagens panorâmicas de alta resolução, formadas a partir de mosaicos de fotografias individuais, capazes de produzirem um documento autêntico e que conseguem resgatar a forma exata da edificação. Normalmente, os métodos preventivos são baseados em informações coletadas em campo por meio de inspeções diretas sobre a edificação e, dependendo do local e do tipo da edificação, podem implicar em tempo e custos elevados de execução, além dos riscos de acidentes. O objetivo deste trabalho é desenvolver um método capaz de identificar, localizar, mapear e fazer o levantamento dos danos existentes nas fachadas das edificações, sem a necessidade do contato direto sobre a edificação, de forma eficaz e tempo reduzido para o levantamento em campo. Com este procedimento pode-se direcionar a inspeção in loco para locais específicos que apresentem danos significativos. As imagens fotográficas foram capturadas por meio de uma câmera digital (acoplada a uma plataforma robótica fotográfica) e foram agrupadas em mosaicos e unidas (“costuradas”) com a utilização de software especializado para a formação das imagens panorâmicas de alta resolução. Os objetos de estudo foram: dois edifícios da Câmara dos Deputados (Anexo I e Anexo IV) do Congresso Nacional e um edifício residencial, todos situados em Brasília – DF (Brasil). A retificação das imagens panorâmicas, assim como a identificação, o mapeamento e o levantamento dos danos foram realizados com os softwares: Autopano GIGA, AutoCAD e ArcGIS. Os resultados obtidos foram satisfatórios e o método pode ser aplicado como uma importante ferramenta para acompanhar as manifestações patológicas ao longo do tempo em um plano de manutenção. __________________________________________________________________________________ ABSTRACT / This study deals with the development of an inspection method of damages on external surfaces of the facades of buildings, through the application of Remote Monitoring System (SMR) based on Digital Photogrammetry. This technique is based on the generation of highresolution panoramic images, formed by mosaics of individual photographs, capable of producing an authentic document that can redeem the exact form of the building. Normally preventive methods are based on information collected in the field by direct inspection on the building and, depending on the location and the type of building, may involve time and high costs of the execution and even risk of accidents. The aim of this work is to develop a method capable to identify, locate, map and make the survey of existing damage on the facades of buildings, without direct contact to the building, effectively and with reduced time of field work. With this procedure the site inspection can be targeted for specific locations presenting significant damage. The images were captured by a digital camera (coupled to robotic platform), grouped in the form of mosaics and stitched with specialized software for the processing of high-resolution panoramic images. The objects of study were two buildings of the House of Representatives (Annex I and Annex IV) of National Congress and one residential building, all located in Brasilia - DF (Brazil). The correction of panoramic images, as well as the identification, mapping and quantification of damage were performed using software such as: Autopano GIGA, AutoCAD and ArcGIS. The results were satisfactory and the method can be applied as an important tool to monitor the pathological manifestations over time in a maintenance plan.
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Implementação de uma montagem experimental em escala reduzida para análise da dispersão de boro em um pressurizador de um reator modular compacto e integralNASCIMENTO, Samira Ruana Vidal do 25 February 2016 (has links)
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Previous issue date: 2016-02-25 / CAPES / Os Small Modular Reactors, SMRs, são reatores modulares compactos variantes dos reatores de geração III+ que apresentam características atrativas, como a simplicidade, maior segurança e são economicamente competitivos. Atualmente, há muitos projetos de SMRs com características estruturais distintas, como potência, tipo de combustível e frequência de abastecimento. O SMR em estudo é um reator do tipo PWR (reator de água pressurizada) que possui o sistema integrado (iPWR). Esse sistema é caracterizado pela inclusão de todo o sistema primário dentro do vaso de pressão, incluindo o gerador de vapor e o pressurizador. Em um iPWR, o pressurizador está localizado no topo do vaso do reator; esta configuração envolve mudanças técnicas como, por exemplo, alteração no mecanismo de circulação adotado para a homogeneização das concentrações de Boro. Assim, o presente trabalho representa uma contribuição para a concepção de uma instalação experimental planejada para fornecer dados relevantes para estudar os fenômenos de homogeneização de Boro no pressurizador de um reator modular compacto. Para isso, foi montada uma instalação experimental com uma seção de teste em aço inoxidável com escala de 1:200, referente a ¼ do pressurizador de um iPWR. Trabalhos anteriores determinaram os principais parâmetros para a construção de um modelo em escala reduzida para análise de dispersão de Boro no pressurizador de um reator com a configuração integral. Esses parâmetros, como medidas dos orifícios e vazão de circulação, foram a base para a execução do projeto referente a montagem experimental. Além da seção de teste, a instalação experimental dispõe de duas bombas rotativas, 5 medidores de vazão e 3 tanques em aço inoxidável, com capacidades de, aproximadamente, 70, 143 e 216 litros. A montagem foi realizada de modo que a seção de teste fosse alimentada com água ou com uma solução com concentração diferente, representando cenários de boração ou deboração. Para determinar a concentração na entrada e na saída da seção de teste, foram realizadas coletas de amostras, a cada 10 minutos, durante os experimentos que representavam alguns cenários (boração/deboração). Utilizando um condutivímetro de bancada, a condutividade elétrica dessas amostras foi determinada e convertida em concentração do elemento traço utilizado. Após a montagem, com as devidas instalações, testes de operação e execução dos experimentos, foi possível comprovar a viabilidade de empregar a montagem experimental, de maneira confiável, para obter valores que possam analisar o fenômeno de homogeneização de Boro em um pressurizador de um reator modular compacto. / The Small Modular Reactors, SMRs, are compact variants modular reactors of generation III + reactors that feature attractive features such as simplicity, enhanced security and are economically competitive. Currently, there are many SMRs projects with distinct structural characteristics such as power, fuel type and supply frequency. The SMR in the study, is a PWR (pressurized water reactor) reactor type that integrated (iPWR). This system is characterized by the inclusion of the entire primary system inside the pressure vessel, including a steam generator and the pressurizer. In one iPWR, the pressurizer is located at the top of the reactor vessel; this configuration change involves techniques such as, for example, change in the movement mechanism adopted for the mixing of boron concentrations. The present work is a contribution to the design of an experimental installation designed to provide relevant data to study the boron homogenization phenomena pressurizer in a compact modular reactor. For this, we assembled an experimental installation with a test section in stainless steel with scale of 1:200, referring to ¼ of the pressurizer of a iPWR. Previous work has determined the key parameters for the construction of a small-scale model for analysis boron dispersion in a reactor pressurizer with the full configuration. These parameters, such as measures of circulation orifices and flow were the basis for the implementation of the design related to the experimental setup. In the test section, the experimental apparatus has two rotary pumps, 5 flow meters and 3 stainless steel tanks with capacities of approximately 70, 143 and 216 liters. The fitting was performed so that the test section was fed with water or a solution with different concentration, or boration scenarios representing deboration. To determine the concentration at the inlet and outlet of the test section, samples have been collected every 10 minutes during the experiments representing some scenarios (boration/deboration). Using a benchtop conductivity, the electrical conductivity of these samples was determined and converted to the concentration of the trace element used. After assembly, with the operation testing and execution of experiments, it was possible to prove the viability of using the experimental setup, reliably, for values that can analyze the boron homogenization phenomenon in a pressurizer of a compact modular reactor.
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Non-proliferation and safeguards aspects of SMR’s in Sweden : A study on the future electricity demand in Sweden and the implications on nuclear safeguards from the deployment of SMRs in SwedenAndersson, Waldemar January 2023 (has links)
This project aims to investigate and analyze crucial aspects related to the deployment of Small Modular Reactors (SMRs) in Sweden. SMRs have risen as a competitor to large-scale nuclear power plants with cost-competitiveness and cogeneration purposes in focus. Alongside the advantages of SMRs, it is important to address the non-proliferation and safeguards aspects of the deployment of SMRs in Sweden. The first stage of this project aimed to predict the electricity consumption in Sweden in 2045. Based on scenarios made by researchers and authorities, a prediction was made that the electricity consumption in Sweden will be approximately 240 TWh in 2045. Subsequently, a study was conducted to assess the suitability of different SMR concepts for deployment in Sweden. The results were that the GE Hitachi BWRX-300 and the Rolls Royce SMR are the concepts most suitable for electricity generation and the VTT LDR 50-SMR is suitable for district heating in Sweden. Based on the predicted electricity consumption and the predicted need for district heating, the SMRs were deployed in three different scenarios which yield the following results: In scenario i), a total of 15-23 SMRs were deployed to the existing nuclear sites in Sweden. (15 SMRs if BWRX-300 is chosen and 23 SMRs if the Rolls Royce SMR is chosen). In scenario ii), 16-24 SMRs in total were deployed to bidding area 1 (SE1), SE2, and SE4. In scenario iii), a total of 25 new reactors were deployed to eight different sites, close to where the electricity consumption was predicted to be large. The implications on material accounting and safeguards from the deployment in the scenarios were that the transportation and storage of spent nuclear fuel will rise by roughly a factor of two, depending on which scenario is chosen and the choice of SMR. There will be more sites for inspectors to visit. New harbors need to be built and licensed. New transportation infrastructure may need to be developed if scenario three is implemented. Furthermore, a new intermediate storage of spent nuclear fuel may be needed.
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