Thesis (M.S.)--West Virginia University, 2010. / Title from document title page. Document formatted into pages; contains viii, 95 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 89-95).

Thesis (Ph. D.)--Drexel University, 2006. / Includes abstract and vita. Includes bibliographical references (leaves 341-367).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Includes bibliographical references (p. 175-180).

Made available in DSpace on 2014-06-11T19:30:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-05-03Bitstream added on 2014-06-13T18:47:26Z : No. of bitstreams: 1 oliveira_ma_dr_ilha.pdf: 1890302 bytes, checksum: bef84d438d9bf156cb579169a5364cf3 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O presente trabalho propõe duas novas metodologias para identificação de danos estruturais aplicados aos sistemas de monitoramento de integridade estrutural. Essas metodologias utilizam somente os sinais de respostas dos transdutores piezelétricos colados na estrutura a ser monitorada. A primeira utiliza o princípio da impedância eletromecânica, sem necessidade de cálculo da resposta em frequência, nem da EMI, pois a análise é realizada a partir dos sinais de resposta dos PZT diretamente no domínio do tempo. Nessa metodologia, transdutores do tipo PZT são colados à estrutura a ser monitorada enquanto um sinal de excitação em uma faixa de frequência apropriada excita o conjunto PZT/estrutura. Um mesmo PZT é usado tanto para excitar a estrutura (atuador) quanto para receber os sinais de resposta da estrutura (sensor). A identificação de possíveis danos estruturais é realizada através de técnicas de processamento de sinais tais como: scores, pesos e pesos rotacionados calculados a partir da PCA. São utilizados ainda os coeficientes do modelo AR. A segunda metodologia é baseada no princípio da função de coerência, na qual um único PZT é usado para excitar a estrutura (atuador) e outros três transdutores PZT são utilizados para receber os sinais de resposta da estrutura (sensores). Nesta metodologia, diferentes técnicas de processamento de sinais no domínio do tempo foram aplicadas diretamente nos sinais de resposta dos PZT. Para isso, os scores e os pesos foram calculados a partir das componentes principais. Outras técnicas, tais como SSA e filtros de Savitzky-Golay, também foram empregadas. Nas duas metodologias, a análise de detecção de falha é baseada em duas métricas estatísticas consagradas na área de SHM: RMSD e CCDM. A fim de testar as metodologias propostas, testes práticos... / This work presents two novel methodologies for damage detection applied to Structural Health Monitoring systems. The proposed methodologies use only response signals of piezoelectric transducers bonded to the host structure. In the first methodology, the analysis is based on EMI (Electromechanical Impedance), however it isn´t necessary to calculate the Frequency Response Function or EMI itself due analysis is carried out directly in time-domain. For this, the PZT are excited by a signal with a wide frequency range and acts as an actuator and also as sensors to receive the signals. The coefficients for AR models and the scores, loadings and rotated loadings (Principal Components) are calculated directly from the time signals. The second methodology is based on Coherence Function. For this, the single PZT is used as an actuator to excite the structure and other three PZT’s are used as sensors to receive the response signals. The scores and loadings (Principal Components) are calculated directly from the time signals. Some techniques of digital signal processing such as Singular Spectral Analysis e Savitzky-Golay filter have also been used. For both methodologies, the damage detection procedures were conducted using statistics metrics useful: RMSD and CCDM. Practical tests were carried out on different aluminum plates and the results... (Complete abstract click electronic access below)

Orientador: Heraldo Luiz Giacheti / Banca: Paulo Cesar de Melo Negrão / Banca: Ana Elisa Silva de Abreu / Resumo: A heterogeneidade hidrogeológica do meio físico é um dos fatores principais na definição da distribuição dos contaminantes e seus subprodutos para elaboração de um Modelo Conceitual da Área (MCA). Existem diversas abordagens para a investigação ambiental de áreas contaminadas, sendo que a investigação de alta resolução (High Resolution Site Characterization - HRSC) permite obter um detalhamento em densidade e escala adequadas, tanto da variabilidade vertical e horizontal da condutividade hidráulica e dos tipos de solo, quanto das concentrações dos contaminantes, sua distribuição e interações no meio físico. Uma das ferramentas de alta resolução utilizada para se definir o Modelo Conceitual do Meio Físico é o piezocone (CPTu), a qual permite avaliar e classificar o tipo de solo e descrever um perfil hidroestratigráfico em escala centimétrica. O presente estudo teve como principal objetivo definir perfis e seções hidroestratigráficas em alta resolução, utilizando amostragem de solo Direct Push Dual Tube Sampling (DPDTS) e ensaios CPTu com Dissipação de Poro-Pressão (PPDT). A amostragem de solo DPDTS permitiu uma caracterização do solo in situ, definindo-se preliminarmente as principais zonas de fluxo e armazenamento de eventual contaminação. Os ensaios CPTu detectaram o tipo de solo em microescala (centímetros), com a identificação adequada das zonas de fluxo e armazenamento, bem como estabeleceram um perfil contínuo de condutividade hidráulica, além também de fornecerem dados ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The hydrogeological heterogeneity of the physical environment is one of the main factors in the definition of the distribution of contaminants and their by-products for the elaboration of a Conceptual Site Model (CSM). There are several approaches to the environmental investigation of contaminated sites, and the High-Resolution Site Characterization (HRSC) allows to obtain an adequate density and scaling detail of both vertical and horizontal variability of hydraulic conductivity and soil types, as well as the concentrations of contaminants, their distribution and interactions in the physical environment. One of the high-resolution tools used to define the Conceptual Model of the Physical Environment is the piezocone (CPTu), which allows to evaluate and classify the soil type and describe a hydrostratigraphic profile in a centimeter scale. The main purpose of the present study was to define high-resolution hydrostratigraphic profiles and sections using Direct Push Dual Tube Sampling (DPDTS) and CPTu tests with Pore-Pressure Dissipation (PPDT). The DPDTS soil sampling allowed an in-situ soil characterization, defining the main flux and storage zones of eventual contaminants. The CPTu tests detected the soil type in microscale (centimeters), with adequate identification of the flux and storage zones, also established a continuous profile of hydraulic conductivity, as well as obtained punctual data through the PPDT tests, thus defining the hydrostratigraphic profile in high reso... (Complete abstract click electronic access below) / Mestre

AIM & HYPOTHESIS: We hypothesized that the piezoelectric knife increases bone remodeling. The effect of a piezotome 2 prototype with different puissance and modulation settings on bone biology was compared under different bone resorption and/or bone formation conditions using an ex-vivo live bone organ culture MATERIALS & METHODS: We utilized an ex-vivo mouse calvarial bone culture system a n d piezocision surgical techniques with variable puissance and modulation settings under conditions of static versus dynamic, and formation versus resorption in order to decipher cellular, molecular, biological and genetic perturbations induced by piezocision surgery. In addition, we tested its impact on calvarial bone organ cultures in the presence of drugs such as bisphosphonate (zolendronic acid, ZOL) and insulin or its impact on bone healing with bone graft material such as Enamel matrix derivative (Emdogain). RESULTS: The impact of the piezoelectric knife extends beyond the immediate site of mineralized bone defect/damage. The impact is ~6 times greater than the apparent initial mineralized bone injury, 1.6 mm2, and extends to immediate surrounding local periosteal and endosteal cell layers, 11 mm2, leaving the mineralized bone layer intact. There were also major differences between the static and dynamic model systems in bone defect viii healing, resorption and new bone formation. There are also differences between the piezoelectric knife and bur in bone resorption and formation models and in both treated before or at the same time of the injury with bisphosphonate. In the calvarial defect repair model the defect closed much faster with the piezoelectric knife than with the bur. In a comparative study with controls versus piezotome or bur, and piezotome versus bur complete genomic analysis of changes revealed a large number of major differences in genomic expression levels. CONCLUSION: The extended effect of piezocision on the surrounding bone lining cells of the bone defect including de-vitalization of the proximal osteocytes within the intact mineralized bone matrix thet primes the bone to undergo rapid turnover. Piezocision incorporates high-frequency vibrational energy that can be transmitted a significant distance within the mineral phase and exploits the inherent bone cellular response mechanism(s) as defined by the global genearray analysis. / 2020-06-13T00:00:00Z

Orientador: Jozue Vieira Filho / Banca: Vicente Lopes Junior / Banca: Nobuo Oki / Banca: Leopoldo Pisanelli Rodrigues de Oliveira / Banca: Fernando Dotta / Resumo: O presente trabalho propõe duas novas metodologias para identificação de danos estruturais aplicados aos sistemas de monitoramento de integridade estrutural. Essas metodologias utilizam somente os sinais de respostas dos transdutores piezelétricos colados na estrutura a ser monitorada. A primeira utiliza o princípio da impedância eletromecânica, sem necessidade de cálculo da resposta em frequência, nem da EMI, pois a análise é realizada a partir dos sinais de resposta dos PZT diretamente no domínio do tempo. Nessa metodologia, transdutores do tipo PZT são colados à estrutura a ser monitorada enquanto um sinal de excitação em uma faixa de frequência apropriada excita o conjunto PZT/estrutura. Um mesmo PZT é usado tanto para excitar a estrutura (atuador) quanto para receber os sinais de resposta da estrutura (sensor). A identificação de possíveis danos estruturais é realizada através de técnicas de processamento de sinais tais como: scores, pesos e pesos rotacionados calculados a partir da PCA. São utilizados ainda os coeficientes do modelo AR. A segunda metodologia é baseada no princípio da função de coerência, na qual um único PZT é usado para excitar a estrutura (atuador) e outros três transdutores PZT são utilizados para receber os sinais de resposta da estrutura (sensores). Nesta metodologia, diferentes técnicas de processamento de sinais no domínio do tempo foram aplicadas diretamente nos sinais de resposta dos PZT. Para isso, os scores e os pesos foram calculados a partir das componentes principais. Outras técnicas, tais como SSA e filtros de Savitzky-Golay, também foram empregadas. Nas duas metodologias, a análise de detecção de falha é baseada em duas métricas estatísticas consagradas na área de SHM: RMSD e CCDM. A fim de testar as metodologias propostas, testes práticos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work presents two novel methodologies for damage detection applied to Structural Health Monitoring systems. The proposed methodologies use only response signals of piezoelectric transducers bonded to the host structure. In the first methodology, the analysis is based on EMI (Electromechanical Impedance), however it isn't necessary to calculate the Frequency Response Function or EMI itself due analysis is carried out directly in time-domain. For this, the PZT are excited by a signal with a wide frequency range and acts as an actuator and also as sensors to receive the signals. The coefficients for AR models and the scores, loadings and rotated loadings (Principal Components) are calculated directly from the time signals. The second methodology is based on Coherence Function. For this, the single PZT is used as an actuator to excite the structure and other three PZT's are used as sensors to receive the response signals. The scores and loadings (Principal Components) are calculated directly from the time signals. Some techniques of digital signal processing such as Singular Spectral Analysis e Savitzky-Golay filter have also been used. For both methodologies, the damage detection procedures were conducted using statistics metrics useful: RMSD and CCDM. Practical tests were carried out on different aluminum plates and the results... (Complete abstract click electronic access below) / Doutor

Abstract In this thesis pre-stressed piezoelectric actuators for micro and fine mechanical applications have been developed. First, RAINBOW (Reduced And INternally Biased Oxide Wafer) and thick film actuators were manufactured and their electromechanical properties were characterised. In the second part, the novel pre-stressed piezoelectric actuator PRESTO (PRE-STressed electrOactive component by using a post-fired biasing layer) was developed and its electrical and electromechanical properties were measured. Commercial piezoelectric PZT 5A and PZT 5H discs were used in the RAINBOW and PRESTO actuators and PLZT paste for thick film actuators. The pre-stressing of the PRESTO actuators was based on the sintering shrinkage and different thermal expansion coefficient of the piezoelectric disc and passive material. Dielectric LTCC tape and AgPd paste were utilized as pre-stressing media and passive layer by using lamination and screen-printing, respectively. Different active and passive layer thicknesses and electrode materials were realized in order to obtain high displacements and good load bearing capability for actuators. The PRESTO actuators showed a significantly higher coercive electric field than their bulk counterparts, but a decreased remanent polarisation. The displacement as a function of load was measured under 0.3–3 N loads and electric fields up to ±0.75 MV/m. The highest displacement of 118 μm was obtained with a 250 μm thick PZT 5H actuator (Ø 25 mm) with LTCC tape (thickness ~96 μm) as the pre-stressing material. The corresponding actuator with AgPd pre-stressing material (thickness ~33 μm) produced 63 μm displacement. Additionally, PRESTO actuators were tested with a glued steel layer in a mechanical amplifier which obtained displacements up to 1.2 mm. Effective d31 coefficients of the PRESTO actuators were derived using an analysis based on unimorph model and measured displacement data. The actuators exhibited significantly enhanced effective d31 coefficients (d31eff = -690 pm/V and d31eff = -994 pm/V for PZT 5A and 5H, respectively) comparable to the RAINBOW actuators. Mass-producible PRESTO actuators with high displacement, moderate load bearing capabilities and integration possibilities can be utilised in various micro and fine mechanical devices e.g. dosing devices, electromechanical locks, regulators, positioners vibrators, speakers, adjusters, pumps, valves, relays, dispensers, micromanipulators, etc.

Magister Chirurgiae Dentium - MChD / To compare the use of a piezoelectric with a standard surgical handpiece in third molar surgery. Thirty patients requiring removal of third molars were included in the study. Panoramic radiographs were used to assess the third molars. The patients were randomly subdivided and the split-mouth technique applied. In split-mouth design, divisions of the mouth, such as right (upper and lower) and left (upper and lower) quadrants constitute the experimental units, which are randomly assigned to two treatment groups. Each patient serves as his or her own control, which increases statistical efficiency (Siddiqi et al. 2010). Each side was operated with either a piezoelectric or a conventional handpiece. All aspects of preoperative care, general anaesthesia, surgery and postoperative care were standardized for the groups. / South Africa

NKN doped samples, (100-x)NKN-xSBN (0 ≤ x ≤ 10) were produced using the conventional mixed oxide route with 0.45 wt% Fe2O3 sintering aid (xSBNF). After 20-24 hours mixing, samples were calcined at 850°C and sintered at 1100–1140°C (± 180°C/hour) for 4 hours. By XRD 4 mol% SBN was found to be the solubility limit for single phase structure. By SEM, second phases were visible when 2 ≤ x ≤ 4; their structure was subsequently shown to be tungsten bronze type (TBT). 2-4 SBNF samples were high density, over 96% theoretical. For x = 0, TC = 457°C, TO-T = 234°C, Pr = 22 μC/cm2 and EC = 16.5 kV/cm. TC was found to decrease by 14.7°C and TO-T by 9.0°C per 1 mol% addition SBN. 2SBNF was the optimal formulation in terms of microstructure and electrical properties, with average grain size 3 μm, Pr = 25 μC/cm2 and EC = 8.8 kV/cm, ρ = 4.7 kΩm and Q = 1.16 eV. This material comprised approximately 90% orthorhombic and 10% tetragonal phases coexisting. Pseudo-cubic lattice parameters are a’ = c’ = 3.947180 Å, and b’ = 3.999996 Å for orthorhombic phase; the tetragonal has a’ = c’ = 3.989798 Å, and b’ = 3.975777 Å.Synchrotron XRD studies were undertaken as a function of temperature on 99.5NKN-0.5CuO + 0.6 wt% Nb2O5 solid and powder samples. The data were Rietveld refined. The solid sample underwent two polymorphic phase transitions at 300°C and 515°C; the latter was between two tetragonal phases: lattice parameters for the tetragonal phase (300-520°C) were a’ = c’ = 4.99557 Å, and b’ = 4.0363 Å; high temperature tetragonal (>500°C) exhibited a’ = c’ = 4.9519 Å, and b’ = 4.4941 Å. The powder sample of the same formulation exhibited more, smaller transformations. It was only orthorhombic at temperatures <140°C with a’ = c’ = 4.10680 Å, and b’ = 4.02620 Å. Above 140°C both orthorhombic and tetragonal phases were present. Another significant transformation occurred at 360°C where the structural unit cell parameters changed significantly. Parameter lengths are provided. P-E data was characterised by Pr = 19.9 μC/cm2 and EC = 13.5 kV/cm. Synchrotron X-ray diffraction analysis of 94 NKN-6LiTaO3 showed that tetragonal phase was present at 20-390°C, although an orthorhombic phase was identified at 20-200°C and again at 340-390°C just before the cubic transition temperature at 390°C. This is a new observation for NKN. A new and simple method for tape casting was developed to reduce powder wastage, enabling thick films of 50 μm to be cast. The reactive templated grain growth (RTGG) method was employed to orient 95NKN-5LiNbO3 and 94NKN-6LiNbO3 samples; CuO was utilised as a sintering aid. Pre-cursor BNN and NN template particles were produced using the molten salt synthesis (MSS) method, using a salt to oxide ratio of 1:1. Resulting NN particles were 15 μm wide and 0.5 μm thick. Eight layered 6LN + 0.4 wt% tapes produced using 10 wt% template particles resulted in 210 μm thick tapes with 67% orientation when sintered at 1150°C. Resulting properties include TC = 440ºC and TO-T = 70ºC, 25 kΩ resistance and capacitance 21.6 pF.