This document focuses on the dynamics of nonlinear oscillatory systems involving widely spaced frequencies. First, experiments on the forced oscillations of a cantilever beam with a circular cross-section are presented. The beam is excited near its fifth natural frequency but sustained large-amplitude oscillations of the first mode accompanied by modulated oscillations of the fifth mode occur. Thus, energy is transferred from the fifth to the first mode of the beam, whose natural frequencies are roughly in the ratio of 60:1. Some simple two-degree-of-freedom systems are studied in an effort to explain the strong nonlinear coupling between modes with widely spaced frequencies. In these systems, the coupling is found to give rise to some novel phenomena including static displacements or sustained oscillations of the low-frequency mode in response to a high-frequency excitation. The possibility that resonances may occur between a high-frequency excitation and a single low-frequency mode is then investigated. A single-degree-of-freedom oscillator driven at a frequency much higher than its natural frequency is analyzed. It is found that, if the excitation is modulated, resonant excitation of the oscillator may occur. / Master of Science

This thesis presents the design and simulation of a digital frequency demodulator applied to a Michelson interferometer-based scanning laser vibrometer. The laser vibrometer is a velocity transducer that produces frequency-modulated signals that have traditionally been optically or electronically frequency shifted from baseband to an intermediate frequency. This shifting produces a narrow band modulation that may be demodulated with standard analog frequency demodulators. This thesis proposes replacing these traditional optics or electronic circuits with a digital frequency demodulator. The optics of a laser vibrometer can be constructed such that a near-perfect baseband quadrature representation is available for the frequency modulation. It will be seen that this representation is well suited for use by a digital frequency demodulator. This thesis applies the arctangent-type digital frequency demodulator to a laser vibrometer and demonstrates its superiority over other digital demodulation techniques. In addition some specialized signal processing to handle the special case of sine-dwell vibration tests is presented. / Master of Science

The effect of PWM frequency modulation on power supply conducted EM! noise emission is investigated. Significant reduction of emission is possible with PWM frequency modulation scheme. A forward converter is used to verify the effectiveness of the scheme. A guidance of parameter selection for noise reduction is given. / Master of Science

Power consumption of smart cameras varies significantly between sleep mode and active mode, and a smart camera operates in sleep mode for 80 — 90% of time for typical use. To prolong the battery life of smart cameras, it is essential to increase the power converter efficiency for light load, while being able to manage heavy load. The power stage of traditional buck converter is optimized for maximum load, at the cost of light-load efficiency. Wei proposed a multiphase buck converter incorporating the baby-buck concept and optimum number of phases (ONP) control. This thesis research investigated Wei's multiphase buck converter to improve the light-load efficiency for smart cameras as the target application. The proposed two-phase buck converter aims to provide power for microprocessors of smart cameras. The input voltage of the converter is 5 V DC, and the output voltage is 1.2 V DC with power dissipation range of 25 mA (30 mW) for light load and 833 mA (1 W) for heavy load. Three methods are considered to improve light-load efficiency: adopting baby-buck concept, adapting ONP control for low-power range, and implementing a pulse frequency modulation (PFM) control scheme with discontinuous conduction mode (DCM) to lower switching frequency. The first method is to adopt the baby-buck concept through power stage design of each phase to optimize efficiency for a specific load range. The baby-buck phase is optimized for light load and the heavy-load phase is designed to handle the processors maximum power consumption. The second method performs phase selection from sensed load current information. Rather than have all phases active for heavy-load as in ONP control, optimum phase selection (OPS) control is introduced to adaptively select between phases based on load current. Due to low-power constraints, OPS is more efficient for the medium to heavy-load range. The transition between phases due to load change is also investigated. The third and final method implements PFM control with DCM to lower switching frequency and reduce switching and driving losses under light load. PFM is accomplished with a constant on-time (COT) valley current mode controller, which uses the inductor current information and output voltage to generate switching signals for both the top and bottom switches. The baby-buck phase enters DCM to lower switching frequency under very light load, while the heavy-load phase remains in continuous conduction mode (CCM) throughout its load range. The proposed two-phase buck converter is designed and prototyped using discrete components. Efficiency of the two-phase converter and a power loss breakdown for each block in the control scheme were measured. The efficiency ranges from 64% to 81% for light load ranging of 30 mW to 200 mW, and the efficiency ranges from 81% to 88% for heavy load ranging from 200 mW to 1 W. The majority loss is due to controllers, which are responsible for 37 % (8.6 mW) for light load of 60 mW and for 10.9 % (9 mW) for heavy load of 600 mW. The gate driver loss is considerable for heavy load of 600 mW, consuming 11.9% (9.8mW). The converter has a 10 mV overshoot voltage for a load step-down from 225 mA to 25 mA, and it has 65 mV overshoot voltage for a load step-up from 25 mA to 225 mA. Although, a fair comparison is difficult due to use of discrete parts for OPS control, the proposed converter shows reasonably good efficiency and performance. / Master of Science

Continuous Phase Frequency Shift Keying (CPFSK) is a constant amplitude modulation of growing popularity in low earth orbit satellites (LEOSAT) because of its spectral efficiency. This thesis compares the error rate performance of CPFSK demodulation using quadrature detectors and phase-locked loops under varying carrier to noise ratios and simulated Doppler shifts, as might be expected for a low earth orbit satellite downlink. Experimental comparison between a quadrature detector and a phase-locked loop demodulator shows that phase-locked loop demodulators and quadrature detectors offer equivalent performance as demodulators at low carrier to noise ratios for narrowband FM/CPFSK systems. This contrasts with earlier work that shows that phase-locked loops can provide threshold extension for wideband FM systems. / M.S.

Small cantilevers with ultra-high resonant frequencies (1–3 MHz) have paved the way for high-speed atomic force microscopy. However, their potential for multi-frequency atomic force microscopy is unexplored. Because small cantilevers have small spring constants but large resonant frequencies, they are well-suited for the characterisation of delicate specimens with high imaging rates. We demonstrate their imaging capabilities in a bimodal frequency modulation mode in constant excitation on semi-crystalline polypropylene. The first two flexural modes of the cantilever were simultaneously excited. The detected frequency shift of the first eigenmode was held constant for topographical feedback, whereas the second eigenmode frequency shift was used to map the local properties of the specimen. High-resolution images were acquired depicting crystalline lamellae of approximately 12 nm in width. Additionally, dynamic force curves revealed that the contrast originated from different interaction forces between the tip and the distinct polymer regions. The technique uses gentle forces during scanning and quantified the elastic moduli Eam = 300 MPa and Ecr = 600 MPa on amorphous and crystalline regions, respectively. Thus, multimode measurements with small cantilevers allow one to map material properties on the nanoscale at high resolutions and increase the force sensitivity compared with standard cantilevers. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

by Wong Chun Kau, Jolly. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 84-88). / ABSTRACT --- p.1 / ACKNOWLEDGEMENT --- p.3 / Chapter 1. --- INTRODUCTION --- p.7 / Chapter 1.1 --- Land Mobile Radio (LMR) Communications / Chapter 1.2 --- Paramilitary Communications Security / Chapter 1.3 --- Voice Scrambling Methods / Chapter 1.4 --- Digital Voice Encryption / Chapter 1.5 --- Digital Secure LMR / Chapter 2. --- DESIGN GOALS --- p.20 / Chapter 2.1 --- System Concept and Configuration / Chapter 2.2 --- Operational Requirements / Chapter 2.2.1 --- Operating conditions / Chapter 2.2.2 --- Intelligibility and speech quality / Chapter 2.2.3 --- Field coverage and transmission delay / Chapter 2.2.4 --- Reliability and maintenance / Chapter 2.3 --- Functional Requirements / Chapter 2.3.1 --- Major system features / Chapter 2.3.2 --- Cryptographic features / Chapter 2.3.3 --- Phone patch facility / Chapter 2.3.4 --- Mobile data capability / Chapter 2.4 --- Bandwidth Requirements / Chapter 2.5 --- Bit Error Rate Requirements / Chapter 3. --- VOICE CODERS --- p.38 / Chapter 3.1 --- Digital Speech Coding Methods / Chapter 3.1.1 --- Waveform coding / Chapter 3.1.2 --- Linear predictive coding / Chapter 3.1.3 --- Sub-band coding / Chapter 3.1.4 --- Vocoders / Chapter 3.2 --- Performance Evaluation / Chapter 4. --- CRYPTOGRAPHIC CONCERNS --- p.52 / Chapter 4.1 --- Basic Concepts and Cryptoanalysis / Chapter 4.2 --- Digital Encryption Techniques / Chapter 4.3 --- Crypto Synchronization / Chapter 4.3.1 --- Auto synchronization / Chapter 4.3.2 --- Initial synchronization / Chapter 4.3.3 --- Continuous synchronization / Chapter 4.3.4 --- Hybrid synchronization / Chapter 5. --- DIGITAL MODULATION --- p.63 / Chapter 5.1 --- Narrowband Channel Requirements / Chapter 5.2 --- Narrowband Digital FM / Chapter 5.3 --- Performance Evaluation / Chapter 6. --- SYSTEM IMPLEMENTATION --- p.71 / Chapter 6.1 --- Potential EMC Problems / Chapter 6.2 --- Frequency Planning / Chapter 6.3 --- Key Management / Chapter 6.4 --- Potential Electromagnetic Compatibility (EMC) Problems / Chapter 7. --- CONCLUSION --- p.80 / LIST OF ILLUSTRATIONS --- p.81 / REFERENCES --- p.82 / APPENDICES --- p.89 / Chapter I. --- Path Propagation Loss(L) Vs Distance (d) / Chapter II. --- Speech Quality Assessment Tests performed / by Special Duties Unit (SDU)

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2016-09-01T14:35:46Z No. of bitstreams: 1 Amanda Giglio Eugenio Barreiros.pdf: 6302661 bytes, checksum: 5e83403b6b9e819563b7ec0e0c25cfee (MD5) / Made available in DSpace on 2016-09-01T14:35:46Z (GMT). No. of bitstreams: 1 Amanda Giglio Eugenio Barreiros.pdf: 6302661 bytes, checksum: 5e83403b6b9e819563b7ec0e0c25cfee (MD5) Previous issue date: 2016-03-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aimed to describe and analyze the Frequency Modulation System - FM (or other wireless transmission system) adaptation process and its consistency of use in the classroom in children with hearing loss, taking into consideration family role relevance as an intermediary between the healthy service system and the school. The participants of this study were children´s parents or guardians, who received the equipment from SUS in Derdic / PUCSP in 2015. As part of the methodology a couple of steps were carried out: medical records analysis, FM equipment adaptation and initial explanations to parents and / or guardians, such as device handling, battery lifetime and transmitter / microphone handling. At the same day, parents were asked to take this information to teachers and two returns were scheduled. At the first return, held a week after the device delivery, three activities were carried out: a speech perception evaluation, an initial interview with parents to obtain non-recorded information and the application of a socioeconomic questionnaire. The second return was held thirty days after the FM delivery, when daily use of the FM system was registered by reading the transmitter record, and another interview with parents was performed, collecting information regarding the use and difficulties encountered. As results, 43.9% children used FM consistently and 56.1% inconsistently. Additionally, it was found that kids with unilateral losses tended to lower use of FM. 25.0% used it consistently and 75.0% inconsistently. There was no statistically significant association in the consistent use of FM when compared to the school characteristics. Most parents reported that their children were using FM, nevertheless, the average hours / day did not confirm this information. It is known that FM system non-consistency of use may lead to lower children´s school performance, reducing their opportunities and learning quality. Nonetheless, the consequences are only measurable in the medium and long term, which may explain why the FM consistent use is low at the beginning. The findings of this study suggested that there should be greater teacher´s monitoring by parents together with an audiologist, who can verify the use of the FM system at the school through direct measurements on the transmitter. Indicators such as the evolution of child´s academic performance might be a good way to track the system use effectiveness in the medium to long term / O objetivo do presente trabalho é descrever e analisar o processo de adaptação e consistência de uso em sala de aula, do sistema de Frequência Modulada – FM (ou outro sistema de transmissão sem fio), em crianças com deficiência auditiva, considerando a relevância do papel da família como intermediária entre o serviço e a escola. Participaram desse estudo pais e/ou responsáveis de usuários do sistema de frequência modulada, que receberam a concessão do SUS na Derdic/PUCSP no ano de 2015. Foi realizada a análise dos prontuários, entrega e adaptação do FM e explicações iniciais para pais e/ou responsáveis, tais como: manuseio do dispositivo, duração da bateria e posicionamento do transmissor e microfone. Neste mesmo dia, os pais e/ou responsáveis foram orientados a levar essas informações aos professores e foram agendados dois retornos. No primeiro retorno, realizado uma semana após a entrega do dispositivo foi realizado avaliação de percepção de fala e a entrevista inicial com os pais, para obter informações que não constavam no prontuário. Nessa ocasião foi também aplicado o questionário socioeconômico. O segundo retorno foi realizado trinta dias após a entrega do FM. Neste momento, foi realizado o registro do uso diário do sistema FM através da leitura do registro do transmissor, e a entrevista com pais e/ou responsáveis, coletando informações quanto ao uso e dificuldades encontradas. Observou-se equilíbrio quanto ao uso do sistema FM. 43,9% utilizaram-no de forma consistente e 56,1% de forma inconsistente. Verificou-se que as crianças com perdas unilaterais tiveram tendência a menor utilização do FM. 25,0% utilizam-no de forma consistente e 75,0% de forma inconsistente. Não foi encontrada associação estatisticamente significativa no uso consistente do FM, quando comparado com as características da escola. A maioria dos pais relata que os filhos estão fazendo uso do FM, no entanto, a média de horas/dia não confirmou essa informação. Sabe-se que a não consistência de uso do sistema FM pode levar a prejuízos no desempenho escolar das crianças, diminuindo as oportunidades e qualidade do aprendizado. No entanto, as consequências só são mensuráveis a médio e longo prazo, o que talvez explique a não adesão imediata ao equipamento. Os achados deste estudo sugerem que deve haver um maior monitoramento dos pais junto aos professores, e um acompanhamento pelo fonoaudiólogo do serviço, que pode monitorar o uso do sistema na escola através de medidas diretas no transmissor. Indicadores como evolução do desempenho acadêmico da criança, podem ser uma boa forma de monitorar a efetividade do uso do sistema

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Radio-frequency filters and oscillators are widely used in wireless communication and high-speed digital systems, and they are mostly built on passive integrated inductors, which occupy a relative large silicon area. This research attempted to implement filters and oscillators operating at 1-5 GHz using transistors only, to reduce the circuits’ area. The filters and oscillators are designed using active inductors, based on the gyrator principle; they are fabricated in standard digital CMOS technology to be compatible with logic circuits and further lower the cost. To obtain the highest operating frequency, only parasitic capacitors were used. Two new active-inductor circuits are derived from this research, labeled allNMOS and all-NMOS-II. The all-NMOS active inductor was used to design high-Q bandpass filters and oscillators, which were fabricated in TSMC’s 0.18-µm digital CMOS process. The highest center frequency measured was 5.7 GHz at 0.20-µm gate length and the maximum repeatably measured Q was 665. 2.4-GHz circuits were also designed and fabricated in 0.40-µm gate length. The all-NMOS-II circuit has superior linearity and signal fidelity, which are robust against process and temperature variations, due to its novel structure. It was used in signal drivers and will be fabricated in commercial products. Small-signal analysis was conducted for each of the active-inductor, filter and oscillator circuits, and the calculated performance matches those from simulations. The noise performance of the active inductor, active-inductor filter and oscillator was also analyzed and the calculated results agree with simulations. The difference between simulation and measured results is about 10% due to modeling and parasitic extraction error. The all-NMOS active-inductor circuit was granted a US patent. The US patent for all-NMOS-II circuit is pending. This research generated three conference papers and two journal papers.