In this study, proton-exchanged (PE) waveguides in Z-cut LiNbO3 and 36¢X-Y LiTaO3 have been fabricated using octanoic acid. The XRD analysis shows that the proton-exchange mechanism is different for LiNbO3 and LiTaO3 substrate, which results in a different variation of SAW velocity. For the temperature coefficient of frequency (TCF) and insertion loss (IL), the absolute values of both increase with the depth of proton-exchanged LiNbO3 and LiTaO3 substrates. In addition, the rf magnetron sputtering method is adopted to deposit SiO2 thin films on LiNbO3 and LiTaO3 piezoelectric substrates. Then the interdigital transducers (IDTs) were fabricated on the bi-layer structure. The film thickness of SiO2 was varied in order to investigate its effect on SAW devices. From the experimental results, TCF of SAW filters increase with the increased thickness of SiO2 thin film. At last, SiO2 thin films were deposited on proton-exchanged LiNbO3 and LiTaO3 substrates, respectively. From the experimental results for the SAW properties on the SiO2/PE-LiNbO3 and SiO2/PE-LiTaO3 structures, it reveals that the TCF of SAW filters increases with the increased thickness of SiO2 thin films. And we can conclude that SiO2 thin films can compensate the TCF of proton-exchanged LiNbO3 and LiTaO3

[pt] Os sistemas micro eletromecânicos são dispositivos na escala dos micras que combinam estruturas mecânicas com circuitos elétricos, e são usados como sensores ou atuadores. Dentro destes dispositivos, estão os de onda superficial acústica (SAW em inglês) que usam variações na velocidade ou percurso de propagação da onda para fazer a detecção da variável a medir. Uma aplicação importante em processos químicos, é no acondicionamento de ambientes, monitorando a umidade. Para isso um sensor SAW comprado, foi coberto em sua superfície com uma camada de um polímero absorvente de vapor de agua. No qual o aumento na massa do polímero na superfície diminui a velocidade da onda. Por tanto o PolyVinyl Álcool foi escolhido para absorver o vapor de agua e foi preparado com 5.6 wt por cento, para ser depositado por meio de spin coating. Então uma serie de experimentos foram feitos numa câmara climática variando tanto a umidade como a temperatura, com o fim de avaliar o comportamento do sensor medindo a sua variação da frequência. Estes resultados foram comparados com um modelo analítico e uma simulação por elementos finitos. O modelo analítico foi presentado por Sielman, o qual determina como muda a densidade e espessura no polímero com a umidade. Estes valores foram substituídos na equação de Wohltjen que dá a variação da frequência de um SAW devido a absorção de gases. Em quanto a simulação por elementos finitos foi feita em Comsol Multiphysics achando a frequência para a qual o SAW ressona, com o aumento da densidade na camada acima do SAW para as umidades inseridas. / [en] Micro electromechanical systems (MEMS) are devices that combine mechanical structures with electrical circuits at the micro scale, to function as sensors or actuators. One type of MEMS are the surface acoustic waves (SAW) devices, which uses the surface wave velocity or propagation path variations to measure the variable of interest. One important application in chemical processes is related to environment condition control, specifically humidity measurement. With that purpose, a commercial SAW was purchased and coated with a polymer layer in its surface. The PolyVynil Alcohol (PVA) was chosen to be the sensing layer in the SAW due to water vapor absorption properties, that increases the mass over the surface and decrease the wave velocity, leading to sense this humidity changes. 5.6wt per cent PVA solution was prepared and deposited through spin coating. Therefore, a series of tests were carried out in a climatic chamber, varying the humidity and temperature conditions, with the aim to analyze the sensor behavior by measuring its frequency shift. These results were compared with an analytical model and a finite element simulation. The analytical model presented by Sielman determines how the polymer density changes with humidity. These density values were inserted into the Wohltjen equation, which gives the frequency shift of the SAW due to gas absorption. Regarding the finite element simulation, it was carried out in the Comsol Multiphysics software, by solving the different resonating frequencies as a function of the increase in the polymer density due to the insets of humidity values.

SAW devices are known for their ability to withstand severe operating conditions. However, their data sheets generally provide very little information on their susceptibility to external factors other than temperature. In particular, no mention is made of their sensitivity to ionizing and non-ionizing radiation, even though they are being used in applications where such radiation is present. In this thesis, we report on experiments that we have conducted to measure the impact of intense gamma and neutron radiation on quartz SAW resonators. Packaged commercial 434 MHz quartz SAW resonators (RFM RP1308) were placed at the output of a Colbalt 60 source and exposed to gamma radiation of up to 50 Mrads. Additional devices were positioned in close proximity to the enriched uranium core of the McMaster University Nuclear Reactor and exposed to intense neutron radiation of 4.5 x 10^12 neutrons/cm^2s for up to 40 seconds. After waiting for a necessary cool-down period, the irradiated SAW resonators were placed in the feedback loop of a custom oscillator to measure the shift in output frequency as a function of radiation exposure. Small changes in the oscillator frequency of up to 15 ppm for the gamma radiation and of up to 10 ppm for neutron radiation were obtained in the experiments. However, no clear relationships were observed between the amount of radiation exposure and frequency shift in either case. / Thesis / Master of Applied Science (MASc)

De tous temps, l'amélioration des moyens de guérison et de prévention des maladies a constitué un enjeu majeur de nos sociétés. Les possibilités offertes désormais par les technologies modernes ont permis de multiplier le nombre d'applications médicales mais toutes ces pratiques nouvelles ont un impact dans le domaine de l'expérimentation animale et impliquent aussi un suivi sanitaire à grande échelle. Le travail présenté dans cette thèse a pour but de moderniser la surveillance de l'état de santé des souris de laboratoire, et s'inscrit dans un projet collaboratif entre le LEAT et TIRO-MATOs. L’objectif est la conception d’un système capable de faciliter ce suivi au quotidien. Pour cela, la conception d'une antenne à 433MHz, connectée à un capteur de température, implantable dans une souris et intégrant notamment l'impact de l'environnement biologique a tout d’abord été étudiée. Après caractérisation des éléments obtenus, la faisabilité d’un système de géolocalisation est présentée. Afin de disposer également de la capacité d’identification des sujets, cette étude s’est poursuivie à 868 MHz (standard RFID). Dans cette partie, l’antenne interrogatrice placée sous la cage, a été plus particulièrement étudiée. Afin de comparer les différentes antennes obtenues, des mesures de puissance récupérées par le lecteur (RSSI) sont réalisées, utilisant pour cela des phantoms de souris spécialement mis au point pour cette étude. Les conclusions tirées par comparaison notamment avec les résultats de phantoms numériques ont permis de concevoir un dispositif de diversité à 4 antennes et de le tester en présence de un à quatre phantoms dans quatre différentes zone de la cage. / The improvement of the methods of cure and prevention of diseases has always constituted a major objective in our societies. The possibilities offered by modern technologies allow the multiplication of the number of medical applications but all these new practices have an impact on pre-clinical animal studies which require a large-scale health status follow-up. This work, which aims at modernizing the supervision of laboratory mice in an animal facility, is a collaborative project between the LEAT and TIRO-MATOs labs. The objective is the design of a system allowing to facilitate this follow-up for the researchers while leading to new research areas. Thus, we first studied the conception of an antenna working at 433MHz, connected to a mouse implanted temperature sensor, taking also into account the biological environment impact. After having characterized the obtained elements, the feasibility of a localization system has been studied. In order to identify several mice within a cage, the study has focused on using an UHF RFID (Radio Identification Frequency) standard (868 MHz). In this part, a reader antenna placed under the cage has been investigated. Different solutions have been proposed and compared thanks to the received power (RSSI level) recorded by the reader. For that purpose, mice “phantoms” have been specifically developed. The comparison of the different results obtained particularly with numerical mice “phantoms”, led to the conception of a reading diversity system composed of 4 antennas. This last system allows to detect the presence of up to four phantoms within a cage divided into four zones.

Neste trabalho apresentaremos os procedimentos para a confecção de substratos de LiNbO3 para dispositivos OAS (Ondas Acústicas Superficiais). Assim como a construção de linhas de atraso, caracterização elétrica e pelo método de \"Laser Probe\". No procedimento experimental, inicialmente descreveremos os métodos e cuidados para a preparação dos substratos do monocristal de LiNbO3 produzido nos laboratórios do Grupo de Crescimento de Cristais do DFCM - IFQSC - USP. Para serem utilizados em linhas de atraso com freqüência central de operação de 70 MHz. Na segunda etapa, descreveremos a construção dos transdutores, o encapsulamento e a caracterização elétrica das linhas de atraso. A caracterização elétrica consta das medidas de impedância das portas de entrada e saída, e da medida de transmissão em um espectro de freqüência do dispositivo OAS. Finalmente, para a caracterização dos substratos confeccionados e util1zados nas linhas de atraso, construímos um sistema óptico, \"Laser Probe, que nos permite medir a velocidade e determinar o campo da onda acústica superficial sobre esses substratos. Apresentamos através do conhecimento do campo acústico, o espalhamento, o desvio de feixe acústico com relação ao alinhamento dos transdutores e as frentes de ondas superficiais em regiões do substrato. Resultados das medidas de perda intrínseca (6 dB) por linha de atraso e o espectro de transmissão dos dispositivos OAS foram apresentados. Sendo a última medida apresentada em comparação com a medida de transmissão da caracterização elétrica / In this work a procedure is presented for fabricating LiNbO3 substrates for Surface Acoustic Wave (SAW) devices. Also described is the construction of SAW delay lines which are characterized using electrical and acoustic-optical methods. Firstly, the experimental methods for producing LiNbO3 single crystal substrates for operation at 70 MHz are described in detail. The single crystals were grown in the crystal growth laboratory of DFCM_IFQSC. Secondly, the techniques for building the transducers are discussed including the encapsulation. The delay lines are then characterized electrically by measuring the impedance of transducers and also the transmission frequency spectra of the SAW devices. Finally, for the characterization of substrates used in delay lines, a laser probe technique was developed, which allows the propagation velocities to be measured. Surface acoustic wave fields in these substrates are then determined making it possible to obtain the scattering, beam steering acoustic and the surface wave fronts in the substrates regions. As an application, results of intrinsic loss (6dB) and pass band measurements in the delay line are presented. These results are found to be in good agreement with previously published data

Neste trabalho apresentaremos os procedimentos para a confecção de substratos de LiNbO3 para dispositivos OAS (Ondas Acústicas Superficiais). Assim como a construção de linhas de atraso, caracterização elétrica e pelo método de \"Laser Probe\". No procedimento experimental, inicialmente descreveremos os métodos e cuidados para a preparação dos substratos do monocristal de LiNbO3 produzido nos laboratórios do Grupo de Crescimento de Cristais do DFCM - IFQSC - USP. Para serem utilizados em linhas de atraso com freqüência central de operação de 70 MHz. Na segunda etapa, descreveremos a construção dos transdutores, o encapsulamento e a caracterização elétrica das linhas de atraso. A caracterização elétrica consta das medidas de impedância das portas de entrada e saída, e da medida de transmissão em um espectro de freqüência do dispositivo OAS. Finalmente, para a caracterização dos substratos confeccionados e util1zados nas linhas de atraso, construímos um sistema óptico, \"Laser Probe, que nos permite medir a velocidade e determinar o campo da onda acústica superficial sobre esses substratos. Apresentamos através do conhecimento do campo acústico, o espalhamento, o desvio de feixe acústico com relação ao alinhamento dos transdutores e as frentes de ondas superficiais em regiões do substrato. Resultados das medidas de perda intrínseca (6 dB) por linha de atraso e o espectro de transmissão dos dispositivos OAS foram apresentados. Sendo a última medida apresentada em comparação com a medida de transmissão da caracterização elétrica / In this work a procedure is presented for fabricating LiNbO3 substrates for Surface Acoustic Wave (SAW) devices. Also described is the construction of SAW delay lines which are characterized using electrical and acoustic-optical methods. Firstly, the experimental methods for producing LiNbO3 single crystal substrates for operation at 70 MHz are described in detail. The single crystals were grown in the crystal growth laboratory of DFCM_IFQSC. Secondly, the techniques for building the transducers are discussed including the encapsulation. The delay lines are then characterized electrically by measuring the impedance of transducers and also the transmission frequency spectra of the SAW devices. Finally, for the characterization of substrates used in delay lines, a laser probe technique was developed, which allows the propagation velocities to be measured. Surface acoustic wave fields in these substrates are then determined making it possible to obtain the scattering, beam steering acoustic and the surface wave fronts in the substrates regions. As an application, results of intrinsic loss (6dB) and pass band measurements in the delay line are presented. These results are found to be in good agreement with previously published data

Among communication filters, SAW Filters have been largely used in RF and IF filters of mobile phone because of their small size, high reliability, and the capability to be mass produced. But with increasing of working frequency and miniaturization of SAW package, SAW filters are more sensitive to interference introduced by the package and SAW Pattern. Discrepancy in performance between design and measurement can be large if the packaging effects are not considered. In this thesis, we use the full wave analysis approach that combining full wave simulator HFSS (High Frequency Structure Simulator) with circuit software to simulate the package effects and the electromagnetic effects of SAW pattern. Our approach has been applied to several cases and measurements are also carried out to verify our results. Good agreements are obtained. We also use this method to discuss the electromagnetic effects inside package, such as the change of the bond wire length. With an accurate prediction, we can save factory design time and production cost.

The thesis project is aimed to automate ultrasonic Time-of-Flight (ToF) technique for saw log classification using signal processing. The ToF technique works in such a way that ultrasonic tone-burst pulses are sent into a saw log, and then the ToF that the pulses take for the propagation is measured and used to calculate the sound speed and further, the Modulus of Elasticity (MoE). Based on the MoE, the quality of the logs is predicted and presorted before sawing. Development of matched filters is the central task for automating the ToF technique.  The whole project was carried out in two different parts: 1) Fundamentals and MATLAB implementation, and 2) Real-time implementation based on digital signal processor.     In the first part, fundamentals on the ToF technique and matched filters have been studied, and then MATLAB simulations of matched filters for automating the technique have been made. After this, test measurements have been conducted. The test results are shown to be consistent with the simulation: matched filtering works well for automating the ToF technique. In the second part of the report, an embedded algorithm has been developed and implemented on a Digital Signal Processor. The algorithm is the first step in the automation of measurements. Eventually, two test measurements have been performed with the DSP. The results were obtained using both oscilloscope to visualize and MATLAB to plot the obtained debug log, and they have shown that the algorithm works, and can automatically measure the ToF, which is in turn used to calculate the sound speed and MoE. The further work on the project that needs to be done, is to applying the developed system to the real situations in sawmills, and improving it according to their requirements.

Non-contact magnetic cutting (NCMC) is a recently developed metal-cutting technology that uses pulsed magnetic fields to advance and steer fine cuts in metal sheet. With this process, a coil is used to induce currents in a workpiece that has a starter feature such as a notch or slit. The induced currents are forced to bend tightly around the starter feature, which enhances the current and magnetic field density. Under the right conditions, resistive heating and large J × B forces cause localized melting and ejection of material. Each cut is only a fraction of a millimeter long; however, the process can be repeated and the coil can be moved to cut arbitrary lengths and shapes. While some promising results have been obtained, the operating space for making controlled cuts appears to be narrow. Furthermore, the process by which cutting occurs is not well understood. The objective of this dissertation is to provide the scientific underpinnings of NCMC by experimentally assessing the conditions for controlled cutting, developing a method for predicting conditions for optimal cutting, and identifying a path to reduce NCMC to practice. / text

The theme of this thesis is design of horizontal band saw and it deals with problems of existing machines on market. Main goal of work is to create effective design and solution of problematic parts, with emphasis on modernization of band saws, which ones processing raw tree trunks.