Dissertations / Theses on the topic 'APEX ANGLE OF THE CONE'

An experimental investigation was performed to ascertain the nature of turbulence in a narrow apex angle isosceles triangular duct. The study involved the design and construction of a low noise, low turbulence wind tunnel that had an isosceles triangular test section with an apex angle of 11.5[degrees]. Experiments involved the measurement of velocity fluctuations using hot wire anemometry and wall pressure fluctuations using a condenser microphone. Measurement of the velocity fluctuations reconfirms the coexistence of laminar and turbulent regions at a given cross section for a range of Reynolds numbers. The laminar region is concentrated closer to the apex while the turbulent region is found closer to the base. The point of transition is a function of the Reynolds number and moves closer to the apex as the flow rate is increased. Moreover, it was found in this investigation that traditional scaling of the turbulent statistical quantities do not hold good in this geometry. Although velocity fluctuations showed distinctive flow regimes, no such distinction could be seen in the dynamic wall pressure data. The nature of the dynamic wall pressure was uniform throughout the entire cross section suggesting that wall pressure fluctuations, unlike the velocity fluctuations, are able to travel from the base to the apex, without being damped. This implies that the relationship between the velocity and the pressure fluctuations applicable in the other systems does not hold well in a narrow apex angle isosceles triangular duct. Further, the typical scaling relationships applied to wall pressure spectra of other geometries doesn't apply in this scenario and the ratio of the RMS pressure fluctuation to the mean shear is much higher compared to a flat plate or pipe flow situation.
Ph.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering PhD

An empirical approach to the study of phosphine compounds was completed using Molecular Mechanics 2 (MM2), and several computer programs written to descibe and analyze the final geometric orientations of the molecules. The calculations were performed on 64 conformers of 16 different phosphines. Results from these calculations were compared to those previously obtained for MNDO and MINDO/3 calculations, and to experimental data. Cone angles calculated from the MM2 optimized geometries, were compared to Tolman's original work, and to values obtained from semiempirical calculations, and to experimental results. In general, it was found that weighted average cone angles best represent the size of phosphine ligands.
Department of Chemistry

Magister Chirurgiae Dentium (MChD)
There is a paucity of studies that make use of the alpha angle as a diagnostic tool to assist with the interceptive treatment, prognosis, treatment duration and surgical outcome of possible maxillary canine impaction in orthodontics. While the literature is replete with studies that utilise the sector method, the alpha angle is an alternative approach to assess the possible eruptive outcome of the unerupted canine. It has been reported that if the alpha angle is greater than 25°, there is the possibility of external root resorption. However, if the alpha angle is more than 31°, the prospect of canine eruption decreases even if the deciduous canine is extracted as an interceptive measure. The dental pantomograph has historically been used to predict canine eruption or possible impaction. The use of this method, however, is wrought with limitations. These limitations include magnification, distortion and blurred images. The use of cone-beam computed tomography has been advocated as a means to overcome these limitations.

In the present work some hadronic properties of the scalar &kappa
meson are studied. Using the QCD sum rules approach, which is a nonperturbative method, the mass and the overlap amplitude of this meson are calculated. As well as the mass and the overlap amplitude, &kappa
&rarr
K^+&pi
^&minus
decay is also studied. For this decay the coupling constant g_&kappa
K^+&pi
^&minus
is obtained using light cone QCD sum rules which is an extension of the QCD sum rules method. Moreover, the coupling constant is calculated using the experimental decay width and it is compared with the value obtained in light cone QCD sum rules approach. The result of the calculation of g_&kappa
K^+&pi
^&minus
, the one obtained from light cone QCD sum rules approach, is also applied to acquire the f_0 &minus
&sigma
scalar mixing angle, &theta
s, using the ratio g^2 (&kappa
&rarr
K^+&pi
^&minus
)/g^2 (&sigma
&rarr
&pi
&pi
) obtained from experimental decay width. The value of scalar mixing angle is also compared with its experimental results.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O objetivo deste estudo prospectivo foi avaliar tridimensionalmente a remodelação e o deslocamento do côndilo mandibular na fossa articular nos indivíduos, pós-surto de crescimento pubertário, tratados com aparelho Herbst bandado. A amostra foi constituída por 24 indivíduos, de ambos os gêneros, leucodermas, com idade cronológica média de 16 anos e 1 mês. Os indivíduos foram tratados com aparelho Herbst bandado por um período de 8 meses (média da amostra: 9,8 meses). Para a avaliação da remodelação do côndilo mandibular foram utilizadas tomografias computadorizadas de feixe cônico (TCFC) em dois tempos, denominados de T1 (antes da colocação do aparelho e T2 (após a remoção do mesmo). As tomografias foram obtidas pelo tomógrafo i-CAT Classic e os dados foram exportados no formato DICOM (Digital Image and Comunication in Medicine) e avaliados no programa Dolphin® Imaging 11.5 Premium. As medidas foram analisadas nas imagens dos cortes multiplanares (planos coronal, sagital e axial) por um observador, previamente calibrado. Os dados obtidos foram calculados pelo sistema de coordenadas cartesianas tridimensionais em um programa de software Matlab desenvolvido pelo Departamento de Física e Biofísica, da Faculdade Estadual Paulista – UNESP de Botucatu. Para avaliar o grau de concordância entre as mensurações empregouse o coeficiente de correlação intraclasse (ICC). À exceção das medidas FOE (eixo Z), C1E (no eixo X) e C2-T2 em ambos os lados, todas as demais medidas apresentaram alto grau de reprodutibilidade, denotando que o erro do método pode ser desprezado. O deslocamento dos côndilos, no sistema de coordenadas cartesianas, foi calculado com o Ponto Zero na Base do crânio; a remodelação foi calculada com o Ponto Zero na média da distância dos forames mentuais direito e esquerdo, forneceu uma análise quantitativa e qualitativa e distâncias euclidianas. Com relação a base do crânio, o côndilo direito se deslocou de forma moderada (0,71mm) para baixo e de forma relevante (0,91mm) para frente; o côndilo esquerdo se deslocou de forma relevante (0,93mm) para baixo e de forma moderada (0,73mm) para frente. O côndilo direito remodelou de forma relevante 1,08mm para trás e se distanciou da média da distância dos forames mentuais de forma relevante (1,19mm); o côndilo esquerdo remodelou de forma relevante 0,98mm para cima e se distanciou da média da distância dos forames mentuais de forma relevante (0,93mm). Foram mensurados os espaçamentos entre os pontos nos côndilos direito e esquerdo, em relação a fossa articular, sendo observado aumento de forma média, do espaçamento superior do côndilo esquerdo (0,34mm). O tratamento não promoveu alterações significantes nas medidas no eixo X, constatando que não houve movimento de lateralidade. Conclui-se que, com relação a base do crânio, os côndilos direito e esquerdo se deslocaram para baixo e para frente. O côndilo direito remodelou para trás enquanto que o côndilo esquerdo remodelou para cima.
The aim of this prospective study was to evaluate in 3-D the remodeling and displacement of the mandibular condyle in the glenoid fossa in the individuals, post-pubertal growth outbreak, treated with the banded Herbst appliance. The sample consisted of 24 individuals of both genders, leucoderma, with a mean chronological age of 16 years and 1 month. Subjects were treated with banded Herbst appliance during 8 months. Cone beam computed tomography (CBCT) was performed in two times to evaluate the condylar remodeling: T1 (prior to placement of the device) and T2 (after removal).) CT scans were obtained by i-CAT tomography Classic and the data were exported in DICOM (Digital Image and Communication in Medicine) format and evaluated in the Dolphin® Imaging 11.5 Premium program. The measurements were analyzed in multiplanar sections images (coronal, sagittal and axial planes) by an observer, previously calibrated. The data obtained were calculated by 3-D Cartesian coordinate system in a Matlab software, developed by the Department of Physics and Biophysics, UNESP Botucatu. To evaluate the agreement degree between the measurements, the intraclass correlation coefficient (ICC) was used. With the exception of the measurements FOE (Z axis), C1E (X axis) and C2-T2 on both sides, all other measurements showed a high degree of reproducibility, denoting that the error of the method can be neglected. The displacement of the condyles in the Cartesian coordinate system was calculated with the Zero Point in the skull base; the remodeling was calculated with the Point Zero in the mean distance of the right and left mental foramina, provided a quantitative and qualitative analysis and Euclidean distances. In relation to skull base, the right condyle moved moderately (0.71 mm) downwards and significantly (0.91 mm) forward; the left condyle shifted significantly (0.93mm) downwards and moderately (0.73mm) forward. The right condyle significantly remodeled 1.08mm behind and distanced itself from the mean distance of the mental foramina significantly (1.19mm); the left condyle significantly reshaped 0.98mm upward and distanced itself from the mean distance of the mental foramina significantly (0.93mm). The spacing between the points on the right and left condyles were measured, in relation to the glenoid fossa; there was a mean increase in the superior space of the left condyle (0.34 mm). The treatment did not promote significant changes in the measurements on the X axis, noting that there was no laterality movement. It was concluded that, with respect to the skull base, the right and left condyles moved downwards and forward. The right condyle remodeled backwards while the left condyle remodeled upward.
2010/17934-8

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This study aimed to evaluate cephalometrically, by means of Cone Beam Computed Tomography (CBCT), the dentoalveolar and skeletal effects of Class II correction ith the Forsus® appliance. Study group was composed by 10 patients, 7 males and 3 females, with initial mean age of 16,1 years, with at least ½ Class II, minimum overjet of 5mm, no supernumeraries, anodontia or permanent teeth loss. Facial pattern should be meso or brachyfacial. Patients were evaluated and it was shown they were at stage IV or V of bone maturation, seen by cervical vertebrae. Forsus utilization period was 7,16 years on average, with a CBCT (T1) before and another one (T2) after the removal of Forsus. Paired t-test was used for statistical analysis. Results showed a decrease of SNA and a small grown of mandible, what improved maxillomandibular relationship; there was a counter-clockwise mandibular rotation and a clockwise rotation of the occlusal plane. Upper incisors were retruded, retroclined and extruded, and upper molars showed distal angulation. Lower incisors were proclined and intruded, and lower molars were mesialized and extruded. So, Forsus appliance showed to be effective in Class II correction, proportioning more dentoalveolar alterations than skeletal changes.
Este estudo teve como objetivo avaliar cefalometricamente as alterações dentoesqueléticas decorrentes do tratamento da maloclusão de Classe II, divisão 1, com o aparelho Forsus®, por meio de Tomografia Computadorizada de Feixe Cônico (TCFC). O grupo avaliado foi composto por 10 pacientes, sendo 7 do sexo masculino e 3 do sexo feminino, com idade média de 16,1 anos, maloclusão com severidade mínima de 1/2 Classe II, trespasse horizontal mínimo de 5 mm, padrão facial meso ou braquifacial. Estes jovens se encontravam no estágio IV ou V de maturação óssea, verificada pelas vértebras cervicais. O tempo de uso do aparelho Forsus foi de 7,16 meses (média), período de avaliação compreendido entre a aquisição da primeira teleradiografia gerada através da TCFC (T1 - pré-Forsus) e da segunda teleradiografia (T2 - pós-Forsus). Para análise estatística foi utilizado o teste-t pareado. Os resultados mostraram um pequeno crescimento mandibular que, juntamente com uma diminuição do SNA levaram a uma melhora da relação maxilomandibular. Houve uma rotação no sentido anti-horário da mandíbula e do plano oclusal no sentido horário. Os incisivos superiores foram retruídos, verticalizados e extruídos e os molares superiores distalizaram por inclinação. Houve vestibularização, protrusão e intrusão dos incisivos inferiores, além de mesialização e extrusão dos molares inferiores. Desta maneira, conclui-se que o aparelho Forsus foi efetivo na correção da maloclusão de Classe II, propiciando maiores alterações dentoalveolares do que esqueléticas.(AU)

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The present study aimed to assess the mesiodistal angle, upper first and second molars distalization and the space for upper third molars in patients treated with Forsus® associated to fixed appliance. Sample consisted of 44 lateral cephalograms (22 right side, and 22 left side) obtained from 11 Cone-Bean Computed Tomography (CBCT) of 11 patients, in two phases: before (T1) and after (T2) the Forsus®. appliance. After obtaining the lateral cephalograms, points, lines and planes were marked, to measure the variables of interest. For evaluation of the space for upper third molars, it was used a reference line (PTVR), from point PTV, perpendicular to Frankfurt plane, measuring the distance until the distal face of first and second upper molars. To evaluate the long axis of upper first and second molars, it was measured the angle formed between such teeth and the palatal plane. The software used was Radiocef Studio 2 and for statistical analysis it was used paired "t" test. Results showed there was distalization and distal tipping of upper first and second molars, with a greater magnitude in first molars. Alterations in right and left sides were similar. It was also noticed that there was a reduction in the probability of eruption of third molars.
A presente pesquisa avaliou a angulação mésio-distal e a distalização dos primeiros e dos segundos molares superiores permanentes em pacientes tratados com o aparelho Forsus® em conjunto com o aparelho ortodôntico fixo. A amostra foi composta por 44 teleradiografias, (22 do lado direito e 22 do lado esquerdo), obtidas por meio de 11 tomografias computadorizadas, de 11 pacientes, realizadas em dois tempos: antes (T1) e após (T2) a instalação do aparelho Forsus®, tratados na clínica de Pós-Graduação em Odontologia, área de Ortodontia, da Universidade Metodista de São Paulo. Após a obtenção dos cortes tipo telerradiografia, foi realizada a marcação dos pontos, linhas e planos, e realizada a mensuração das variáveis de interesse. Para avaliação do espaço para os terceiros molares superiores, utilizou-se uma linha referencial (linha PTVR), demarcada a partir do ponto PTV, perpendicular ao plano de Frankfurt. O espaço avaliado compreendeu entre a Linha PTVR, até a face distal do primeiro molar e do segundo superior permanente. Para avaliar o longo eixo dos primeiros e segundos molares superiores, mensurou-se o ângulo formado entre esses dentes e o plano palatino. Para auxílio das mensurações, foi utilizado o software Radiocef Studio 2. Na análise estatística usou-se o teste t pareado. Concluiu-se que houve distalização e aumento da angulação distal dos primeiros e segundos molares superiores, sendo que nos segundos molares a distalização e angulação distal da coroa ocorreram em menor quantidade; os efeitos do lado direito e esquerdo foram semelhantes; pode-se também constatar que ocorreu uma redução na probabilidade de erupção dos terceiros molares superiores.

The design and optimisation of a modern gasoline direct injection (GDI) engine requires a thorough understanding of the fuel sprays characteristics and atomisation process.Therefore this thesis presents a detailed optical analysis of atomisation, penetration and interaction of multi-stream GDI sprays under engine relevant pressures and temperatures. The characteristics of the fuel spray in a GDI engine have a great influence on the fuel-air mixing and combustion processes as fuel injectors must provide adequate atomisation for vaporisation of the fuel to take place before combustion is initiated, whilst also avoiding spray impingement on the cylinder walls or piston crown. In this study multi-stream injectors, to be used within GDI engines, are quantified using Laser Doppler Anemometry (LDA) on an atmospheric bench. This process allowed for highly detailed spray analysis of droplet velocities and diameter at precise locations, using a three dimensional traverse, within the injector spray. The aim of the study was to analyse plume interaction between separate plumes of multi-stream injectors. Three multi-stream injectors were subjected to testing; two six-hole injectors and one three-hole injector. The injectors differed by having different distances between the plumes. The effect of fuel type on the liquid break-up and atomisation was investigated using Phase Doppler Anemometry (PDA) and Mie imaging. Mie imaging was also performed to capture images of fuel from a multi-stream injector as it was sprayed into a pressure chamber which was used to recreate the conditions found in an engine likely to cause flash boiling. In total, five variables were investigated: fuel pressure, ambient pressure, ambient temperature, fuel composition and injector geometry. Once processed, the recorded images allowed measurement of spray tip penetration and cone angle. Qualitative data on the change in shape of the spray was also available. The results showed that flash boiling has potential to reduce droplet diameters and improve fuel vaporisation, however, the associated change in spray shape must be taken into account to avoid problems with spray impingement. Keywords: Gasoline Direct Injection, multi-stream injector, atomisation, penetration, cone angle, Mie imaging, Phase Doppler Anemometry, flash boiling.

Thesis (M.S. in Aeronauticl Engineering)--Naval Postgraduate School, June 2003.
Thesis advisor(s): Garth V. Hobson, Raymond P. Shreeve. Includes bibliographical references (p. 67). Also available online.

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Because the consequences of the use of fixed orthopedic appliances on buccal and lingual periodontal bone are still a mystery to the orthodontist and to the clinical research, this study aimed to evaluate, using cone beam computed tomography (CBCT) changes in thickness plates of buccal and lingual bone in first molars and lower incisors and canines, after the use of fixed appliances and Twin Force (Group A) or Forsus (group B) appliances for the treatment of Class II, Division 1 malocclusion. To this end, we obtained a sample of 22 young adults, divided into two groups, according to the mandible s propulsion device. The experimental group A: 11 patients, six male and five female, mean age of 15.09 years in the Twin Force installation, and 11 patients, seven male and four female, mean age of 15.45 years in the installation of Forsus. The average time of using the Twin Force was 3.73 months and Forsus, 7.09 months. Group A had CBCT before starting the treatment (T1), before installing the Twin Force (T2), after removing the Twin Force (T3) and in group B just before the installation of Forsus (T2) and after removal it (T3). For comparison between times T2 and T3 was used paired t test, and between times T1, T2 and T3 was used analysis of variance (ANOVA) one-criterion and a Tukey s post-hoc test. For comparison between groups was used the t -test. In the inter-groups comparison between the results showed no statistically significant difference between changes in bone thickness of buccal and lingual plates; on the other hand, in the intra-group evaluation, in 48 measures evaluated, in group A, were statistically significant reductions in the buccal cervical thirds of lower anterior teeth and upper first molars, and increased cervical and middle thirds on lingual lower anterior teeth, totaling 25 significant measures. In group B, there was a significant increase in lingual bone plate on lower anterior teeth and reduction on buccal upper molars, totaling only seven significant measures, but there was more significant measures of reduction bone in buccal cervical and middle thirds in the first upper molars, in comparison with group A. There was no significant difference between the measurements obtained with voxel 0.2 mm and 0.4 mm and no sexual dimorphism. The reductions on alveolar bone thickness, especially in cervical and middle thirds buccal teeth evaluated in this study is an alert to the clinician to do this periodontal diagnostic approach before starting the orthodontic treatment.
Pelo fato das consequências do uso de aparelhos ortopédicos fixos sobre o periodonto ósseo vestibular e lingual ainda serem uma incógnita para o ortodontista clínico e pesquisador, este estudo teve como objetivo avaliar, por meio de tomografia computadorizada de feixe cônico (TCFC) as alterações em espessura das tábuas ósseas vestibulares e linguais em primeiros molares superiores e incisivos e caninos inferiores, após a utilização de aparelhagem fixa e dos aparelhos Twin Force (grupo A) e Forsus (grupo B) para o tratamento da maloclusão de Classe II, 1ª divisão. Para tanto, obteve-se uma amostra de 22 pacientes jovens adultos, divididos em dois grupos, de acordo com o aparelho propulsor da mandíbula. Grupo experimental A: 11 pacientes, 6 masculinos e 5 femininos, com idade média de 15,09 anos na instalação do Twin Force, e 11 pacientes, 7 masculinos e 4 femininos, com idade média de 15,45 anos na instalação do Forsus. O tempo médio de uso do aparelho Twin Force foi de 3,73 meses e do Forsus, 7,09 meses. O grupo A realizou TCFC antes do início do tratamento (T1), antes da instalação do Twin Force (T2), após a remoção do Twin Force (T3); e o grupo B somente antes da instalação do Forsus (T2) e após a remoção do Forsus (T3). Para comparação entre os tempos T2 e T3 foi utilizado o teste t pareado e entre os tempos T1, T2 e T3 foi utilizada a Análise de Variância (ANOVA) a um critério e o teste post-hoc de Tukey. Para comparação entre os grupos foi utilizado o teste t . Na comparação intergrupos os resultados evidenciaram que não houve diferença estatisticamente significante entre as alterações das espessuras das tábuas ósseas vestibular e lingual; por outro lado, na avaliação intra-grupo, de 48 medidas avaliadas, no grupo A houve reduções estatisticamente significantes nos terços cervical e médio por vestibular, nos dentes anteroinferiores e nos primeiros molares superiores e aumento nos terços cervical e médio, por lingual nos dentes anteriores inferiores, totalizando 25 medidas significantes. Já no grupo B, houve aumento significante da tábua óssea lingual nos dentes anteriores inferiores e redução em vestibular nos molares superiores, totalizando apenas sete medidas significantes, mas com mais medidas significantes de redução óssea vestibular em terços cervical e médio nos primeiros molares superiores, em comparação com o grupo A. Não houve diferença significante entre as medições obtidas com voxel 0,2 mm e 0,4 mm e nem dimorfismo entre os gêneros. As reduções em espessura óssea alveolar, principalmente em terços cervicais e médios vestibulares nos dentes avaliados neste estudo são um alerta ao clínico, para que realize essa abordagem diagnóstica periodontal antes de iniciar o tratamento ortodôntico.

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Introduction Strategies to obtain the working length to prepare and fill the root canals has been relevant theme of discussion in endodontics. The purpose of this study was to compare in vivo the canal root working length measures determined by cone beam computed tomography (CBCT) images with the ones obtained by using periapical radiograph and electronic apex locator. Methods The root canal working lengths of 30 single-rooted teeth from 19 patients whose diagnosis was apical periodontitis were evaluated. Initial periapical radiographs for diagnosis and treatment planning, employing the parallelism technique, were taken. CBCT images were acquired with i-CAT system (aiming of diagnosing the cases of apical periodontitis that showed to be complex and doubtful) and measured with specific function of i-CAT software. The coronal opening was made, the root canals were irrigated with sodium hypochlorite solution 2.5%, being performed the exploration and initial emptying of root canal. After, the preparation of the inlet orifice and of the cervical root third was carried out . The minor foramen was located using Root ZX® locator by advancing a stainless steel K-file that best suited the root canal, according to the manufacturer´s instructions. The radiographic measurement was made by advancing a stainless steel K-file in the root canal, until its tip was 1.0 mm from the root apex (determined from the measures obtained by the electronic ape locator). These 3 working length were tabulated and compared. Kruskal-Wallis test was used to analyze the differences between working lengths methods. The significance was set at α=5%. Results The mean values and standard deviations for working length determination by electronic apex locator, periapical radiograph and CBCT images were 21.5 ± 3.1, 21.32 ± 3, 21.4 ± 2.7, respectively. Significant differences were not verified statistically (P>0.05). Conclusions CBCT images working length determination showed to be as similar as the determinations obtained by using periapical radiograph and electronic apex locator.
Introdução: Estratégias para obtenção do comprimento de trabalho para preparar e obturar canais radiculares têm sido tema relevante de discussão em Endodontia. O objetivo deste estudo foi comparar in vivo as medidas de comprimento de trabalho do canal radicular determinadas por meio da tomografia computadorizada de feixe cônico (TCFC) com as obtidas por meio de radiografia periapical e localizador apical eletrônico. Metodologia: Foram avaliados os comprimentos de trabalho dos canais radiculares em 30 dentes de 19 pacientes com diagnóstico de periodontite apical. Radiografias periapicais iniciais de diagnóstico e plano de tratamento, empregando a técnica do paralelismo, foram realizadas. As imagens de TCFC foram obtidas usando o sistema i-CAT (com o intuito de diagnosticar os casos de periodontite apical que se mostraram complexos ou duvidosos) e foram medidas a partir de função específica do programa desse sistema. Foi realizada a abertura coronária, os canais radiculares foram irrigados solução de hipoclorito de sódio a 2,5%, sendo realizada a exploração e o esvaziamento inicial do canal radicular. Depois foi realizado o preparo do orifício de entrada e do terço cervical da raiz. O forame apical foi localizado usando o localizador Root ZX® por meio do avanço de uma lima tipo K-file que melhor se adaptasse ao canal radicular de aço inoxidável no canal radicular, de acordo com instruções do fabricante. A medida radiográfica foi feita por meio da colocação de uma lima tipo K-file de aço inoxidável no canal radicular, até que sua ponta estivesse a 1,0mm do ápice radicular (determinado pelas medidas obtidas com o localizador apical eletrônico). Essas três medidas de comprimento de trabalho foram tabuladas e comparadas. O teste de Kruskal-Wallis foi empregado para analisar as diferenças entre os métodos de obtenção dos comprimentos de trabalho. O nível de significância foi estabelecido em α=5%. Resultados: O valor médio e os desvios-padrões para a determinação do comprimento de trabalho por meio de imagens de TCFC, localizador apical eletrônico e radiografia periapical foram de e 21,4 ± 2,7, 21,5 ± 3,1, 21,32 ± 3, respectivamente. Diferenças significantes entre as medidas obtidas pelos três métodos não foram verificadas (p>0.05). Conclusões: A determinação do comprimento de trabalho em imagens de TCFC mostrou ser tão similar quanto às determinações obtidas por meio do método radiográfico e do localizador apical eletrônico.

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O objtivo deste estudo pros

Made available in DSpace on 2016-08-03T16:30:58Z (GMT). No. of bitstreams: 1 Jin Hyun Kim.pdf: 2911975 bytes, checksum: f52f85e0769d576a5d47e7bf335d3973 (MD5) Previous issue date: 2011-10-19
This study evaluated the skeletal effects of maxillary protraction using 2D images (lateral radiograph) generated from the cone beam CT (3D images). The sample consisted of 20 children (15 females and 5 males), aged 5,6 -10,7 years who had malocclusion Class III malocclusion. CT was performed before treatment (T1) and after treatment (T2). The treatment was performed by maxillary protraction using the Hyrax expansion appliance associated with individualized face mask with the force of 600 to 800g each side for 14 hours a day. The correction of canine relationship in Class I or Class II in their overcorrection was obtained after 4-7 months of treatment. To check the systematic error and random test was used for paired "t" and the formula of Dahlberg, respectively. The test paired "t" (p <0.05) showed a significant difference between the cephalometric measurements obtained in T1 and T2. In the maxilla there were increases in SNA 2.2°, Nperp A 1.47mm and Co-A 2.58mm. In the mandible, SNB decreased by -0.54° and P-Nperp, -1.45mm, while Co-Gn increased 1.04mm. There was improvement in maxillomandibular relationship ANB 2.74° and Wits 4.23mm. Variables GoGn.SN, Gn.SN, FH.Md, Mx.Md and AFAI demonstrating that there was an increased rotation of the mandible in a clockwise direction. The palatal plane rotated in a counterclockwise direction. It can be concluded that the treatment ofmaxillary protraction in early age has promoted an improvement in maxillomandibular relationship due to a shift of the jaw forward and a displacement of the mandible down and back.
Este estudo avaliou os efeitos esqueléticos da tração reversa da maxila utilizando imagens 2D (telerradiografia lateral) geradas a partir da tomografia de feixe cônico (imagens 3D). A amostra foi composta por 20 crianças (15 do gênero feminino, e 5 do masculino), com idade variando de 5,6 a 10,7 anos que apresentavam má-oclusão de Classe III de Angle. A tomografia foi realizada antes do tratamento (T1) e logo após o tratamento (T2). O tratamento foi realizado por meio da tração reversa da maxila utilizando-se o aparelho expansor Hyrax associado à máscara facial individualizada, com força de 600 a 800g de cada lado, durante 14 horas por dia. A correção da relação de caninos em Classe I ou com sua sobrecorreção em Classe II foi obtida após 4 a 8 meses de tratamento. Para verificar o erro sistemático e casual foi utilizado o teste t pareado e a fórmula de Dahlberg, respectivamente. O teste t pareado (p<0,05) mostrou diferença significante entre as medidas cefalométricas obtidas em T1 e T2. Na maxila houve aumento do SNA 2,2°, A-Nperp 1,47mm e em Co-A 2,58mm. Na mandíbula, SNB diminuiu -0,54° e P-Nperp, -1,45mm, enquanto Co-Gn aumentou 1,04mm. Houve melhora na relação maxilo-mandibular ANB 2,74° e Wits 4,23mm. As variáveis GoGn.SN, Gn.SN, FH.Md, Mx.Md, e AFAI aumentaram demonstrando que houve uma rotação da mandíbula no sentido horário. O plano palatino rotacionou no sentido anti-horário. Pode se concluir que o tratamento de tração reversa da maxila na idade precoce promoveu uma melhora na relação maxilo-mandibular devido a um avanço da maxila e um deslocamento da mandíbula para baixo e para trás.

The master’s thesis deals with photometry units used in light engineering. There are defined the methods of modelling the illumination systems, their advantages, disadvantages and possibilities of using. Furthermore, the thesis deals with modelling of two illumination systems by ray-tracing in programming environment of MATLAB. The master’s thesis describes the analysis of the problem and the program designing process. Acquired model results are then compared with the real measurements of both illumination systems which allow the discussion of the results and the deviations of the models.

Дисертаційна робота присвячена визначенню впливу вільних параметрів фокусуючих полів на густину струму в зонді для систем формування прецизійних пучків іонів МеВ-х енергій у ядерному скануючому мікрозонді (ЯСМЗ). Як вільні параметри запропоновані додаткові джерела живлення магнітних квадрупольних лінз і кути конусності апертури. Результати проведеного числового моделювання зондоформуючої системи (ЗФС) на базі мультиплетів магнітних квадрупольних лінз (МКЛ) показали, що оптимізація процесу формування пучка з додатковими джерелами живлення лінз, яка ґрунтується на знаходженні найбільшого зведеного колімованого аксептанса, може забезпечувати значне поліпшення іонно-оптичних характеристик ЗФС. Для ЗФС на базі дублета і триплету МКЛ із додатковими параметрами у вигляді кутів конусності показано, що величина максимального зведеного колімованого аксептанса для конвенціальних систем поступається системам із МКЛ із конусною апертурою у разі дублета в півтора раза, а для триплету – більше, ніж у два рази. Отримані експериментальні результати підтверджують теоретичні розрахунки, у результаті яких робили висновок, що густина струму в зонді для системи квадруплета з індивідуальними джерелами живлення лінз перевищує аналогічну величину для широко поширеної ЗФС, розподіленого «російського» квадруплета, у три рази. У результаті можна зробити висновок про те, що процес експонування сфокусованим протонним пучком при внесенні фіксованої дози опромінення у разі застосування нової зондоформуючої системи може бути прискорений більше ніж у три рази. Це становить певний прогрес у застосуванні літографічної технології proton beam writing. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/33748
Диссертационная работа посвящена определению влияния свободных параметров фокусирующих полей на плотность тока в зонде для систем формирования прецизионных пучков протонов МэВ-х энергий в ядерном сканирующем микрозонде (ЯСМЗ). В качестве свободных параметров предложены дополнительные источники питания магнитных вадрупольных линз (МКЛ) и углы конусности апертуры. Проведен анализ методов решения нелинейных траекторных уравнений движения заряженных частиц в магнитных квадрупольных зондоформирующих системах (ЗФС) со свободными параметрами фокусирующих полей, в результате которого было установлено, что наиболее приемлемым методом является матричный метод. Для решения нелинейных траекторных уравнений движения заряженных частиц матричным методом выбрана модель продольного распределения поля в МКЛ с конической апертурой. Получен аналитический вид матрицы преобразования фазовых координат частиц пучка – матрицанта. Учитывая условия создания наноструктур с помощью технологии proton beam writing (PBW), было предложено, что критерий качества ЗФС должен основываться на принципах обеспечения максимального тока пучка при заданных размерах зонда на мишени. Согласно этому наиболее приемлемым методом оптимизации является метод, который основан на критерии максимального аксептанса системы. Результаты проведенного численного моделирования ЗФС на базе мультиплетов МКЛ показали, что оптимизация процесса формирования пучка с дополнительными источниками питания линз, которая основана на нахождении наибольшего приведенного коллимированного аксептанса, может обеспечивать значительное улучшение ионно-оптических характеристик ЗФС. Для триплета МКЛ с индивидуальными источниками питания величина аксептанса больше на 50 %, для квадруплета и пентуплета – в два раза. На основании проведенного анализа можно утверждать, что с уменьшением рабочего расстояния величина аксептанса системы возрастает, в то время как положение линз системы согласования несущественно влияет на характеристики ЗФС. Анализ влияния числа квадрупольных линз, геометрии их расположения и величины рабочего расстояния на плотность ионного тока показал, что с уменьшением рабочего расстояния величина аксептанса системы увеличивается, в то время как положение линз системы согласования несущественно влияет на характеристики ЗФС. Для ЗФС на базе дублета и триплета МКЛ с дополнительными параметрами в виде углов конусности показано, что величина максимального приведенного коллимированного аксептанса для конвенциальных систем уступает системам с МКЛ с конусной апертурой для дублета в полтора раза, а для триплета – более, чем в два раза. Применение магнитных квадрупольных линз с конусной апертурой в системах формирования зонда открывает возможность к разработке квадруполей на постоянных магнитах, так как изменение угла конусности приводит к изменению оптической силы линзы и обеспечивает возможность юстировки системы, что в конечном итоге дает возможность отказаться от источников тока питания линз, а также снижает энергетические затраты. Полученные экспериментальные результаты подтверждают теоретические расчеты, в результате которых делалось заключение, что плотность тока в зонде для квадруплета с индивидуальными источниками питания превышает аналогичную величину для широко распространенной ЗФС, распределенного «русского» квадруплета, в три раза. Средняя плотность тока в зонде для квадруплета с индивидуальными источниками питания составляет 2 123 пкА/мкм , в то время как для зондовой системы распределенного «русского» квадруплета эта величина равна 2 37 пкА/мкм , где учтено, что для первой системы в зонде сосредоточено 70 % полного тока пучка, а для второй эта величина равна 90 %. Таким образом, процесс экспонирования сфокусированным протонным пучком при внесении фиксированной дозы облучения в случае применения новой зондоформирующей системы может быть ускорен более чем в три раза. Это представляет определенный прогресс в применении литографической технологии PBW. При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/33748
The thesis reveals the questions about the free parameters of the focusing fields influence om the current density in the probe for the precision MeV energies proton beams in the nuclear scanning micro-probe (NSMP). Additional power supplies of the magnetic quadrupole lenses (MQL) and the aperture cone angles were proposed as free parameters. The results of the probe-forming systems (PFS) numerical simulations, which were based on the multiplets of the MQL, showed that the optimization process beam forming with the additional power supplies of the lenses can provide a significant improvement of the ion-optical characteristics of the PFS. This optimization process bases on finding the largest reduced collimated acceptance. For the PFS, which was based on the doublet and triplets of the MQL with the additional parameters in the form of the cone angles, it was shown that the magnitude of the maximum reduced collimated acceptance for the conventional systems is less than for the systems with MQL of the conical aperture. In the case of the doublet this magnitude is 1,5 times more, and for the triplets it is more than 2 times. The experimental results confirm the theoretical calculations, which result in the conclusion that the current density in the probe for the quadruplet of the magnetic quadrupole lenses with the individual power supplies exceed three times than a similar magnitude for the widespread worldwide PFS, distributed "russian" quadruplet. As a result, we can conclude that the process of writing by the focused proton beam with making a fixed dose in the case of using new probe-forming system can be hasten more than three times. This represents some progress in the application of a lithographic technology proton beam writing. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/33748

Recognition of the importance of soil compaction is increasing, but instrument cost, repeatability of measurements, and data interpretation restricts its measurement. Developed by Scala (1959), the dynamic cone penetrometer (DCP) device has been substantially utilized in recent decades for quality control of compaction of soils. The dynamic cone penetrometer described in this study follows the design of the American Society of Testing and Materials standards. The penetrometer cone is pushed into the soil by giving successive hammer blows. Penetration resistance is calculated as the work done by the soil needed to stop the motion of the cone divided by the distance that the cone penetrates. The work done by the soil is defined as the kinetic energy of the hammer while it impacts the strike plate. The height of fall of the hammer has been varied for each test to vary the kinetic energy on impact. The effect of the variation of the apex angle of the cone on the Dynamic Cone Penetration Index(DCPI) and the soil penetration resistance has also been studied in this work. Numerous cone angles other than the standard 60 degree cone were designed and used for testing the effects and the results have been compared. The results show that the average soil penetration resistance obtained for a depth of 15 cm is almost similar for the various tests on the same soil sample, each with a different height of fall of the hammer. The penetration resistance for four soil samples was then calculated using a fixed height of fall of 400 mm for each. The results also show that the DCPI value decreases as the apex angle of the cone is increased further from the standard 60°, although this similar sort of trend is not observed for the lower values of the cone angle.

The main purpose of this thesis is the development of a new methodology of contact angle measurement called ADSA-NA (Axisymmetric Drop Shape Analysis - No Apex) that analyzes drop shape configurations with no apex. Thus ADSA-NA facilitates contact angle measurements on drops with a capillary protruding into the drop. This development is desirable because the original ADSA has some limitations for contact angle measurement, and there is a need for the improvement of the accuracy of contact angle measurement. To develop ADSA-NA, a new reference point other than the apex and a new set of optimization parameters different from those of ADSA had to be defined. The three main modules of ADSA had also to be modified; the image analysis, the numerical integration of the Laplace equation for generating theoretical curves, and the optimization procedure. It was shown that ADSA-NA significantly enhances the precision of contact angle and surface tension measurements (by at least a factor of 5) compared to those obtained from sessile drops using ADSA. Computational as well as design aspects of ADSA-NA were scrutinized in depth, well beyond the level of scrutiny in the original ADSA. On the computational side, the results obtained from one and the same drop image were compared using different gradient and non-gradient edge detection strategies and different gradient and non-gradient optimization methods. It was found that the difference between the results of different edge detection strategies is minimal. It was also found that all the optimization methods yield the same answer with eight significant figures for one and the same image. The determination of the location of the solid surface in the drop image was also further refined. On the design side, the effect of controllable experimental factors such as drop height and drop volume on the accuracy of surface tension measurement was studied. It was shown that drop height is the dominant experimental factor, and larger drop heights yield lower surface tension errors.

Isothermal, incompressible jets of air issuing from sharp-edged isosceles triangular orifices with apex angles of 10°, 20°, 30°, 70° and 160° into still surrounding air, were used to study the effects of apex angle variation on flow development in the jets. Some measurements were made in two round jets issuing from a sharp-edged orifice and from a contoured nozzle. The mean streamwise centreline velocity decay, mass entrainment and spreading results show that the 160° jet, which originates from the orifice with the longest perimeter, has the highest mixing rate in the near flow field. The results also suggest that the 10° jet, which originates from the orifice with the second longest perimeter, has the highest mixing rate in the far field. The results demonstrate that all the triangular jets have higher mixing rates than the round jets, throughout the flow region investigated.

碩士
國立臺灣大學
土木工程學研究所
100
In engineering analysis and design, the value of soil friction angles used were mainly obtained from triaxial test. However, considering the cost and time-consuming of triaxial tests, cone penetration tests have its advantage of cost and time-saving, and convenience. Hence, this research focuses on the relationships between spatial variability of friction angles acquired from triaxial tests and cone penetration tests. The clarification of this relationships helps to make it possible to seek the spatial variability of design friction angles through the spatial variability of cone resistance. Variance and scale of fluctuation (SOF) are two important parameters to define spatial variability. Thus, it is crucial to understand the relationships, for example, the relationships between SOF of cone resistance and SOF of friction angle, in order to obtain one from another. Since the deformation during cone penetration tests is relatively high, continuum analysis may not be a suitable method, a distinct element method PFC3D were taken throughout this research. Specimen with spatial variability were created and repeated to generate sufficient data. The results show that, it is reasonable to assume that the cone resistance does not induce average effect of soil strength. Yet average effect would occur during triaxial tests for the contact area is larger with respect to cone penetration tests. The soil strength of a triaxial test is the average of 3 to 4 points on failure surface, rather than surface average or volume average

碩士
國立成功大學
生物醫學工程學系
105
Computed tomography (CT) is already an indispensable tool and widely applied in clinical diagnosis, so is cone beam computed tomography (CBCT) in maxillofacial, limb and dental applications. Radiation dose reduction of CBCT remains to be an active topic of research. In the literature, image reconstruction with limited angles can directly reduce the radiation dose, and the iterative reconstruction algorithms have superior performance on limited angles reconstruction. Although there are many kinds of iterative reconstruction algorithms, there is no systematic and objective comparison of these iterative reconstruction algorithms. In this work, we compared five common iterative reconstruction algorithms to the non-iterative algorithm, the L. A. Feldkamp, L. C. Davis, and J. W. Kress (FDK) algorithm, which is common in clinical use, to evaluate which iterative reconstruction method is preferred in limited angle reconstruction. Methods: To set up a prototype CBCT system, we integrated three hardware components: X-ray tube, flat-panel detector and a motor with in-house controlling software. Acquired projection data were used to reconstruct image volumes with tomographic iterative GPU-based reconstruction toolbox (TIGRE), an open source toolbox of various image reconstruction methods. A micro-CT bar pattern phantom and anolis sagrei cadaver were used as irradiated objects. We analyzed the reconstructed images with image quality criteria of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), universal quality Index (UQI ), root mean of the squared error (RMSE) and full width at half maximum (FWHM). Results: Inspecting the coronal and sagittal planes of the reconstructed results, MLEM, OS-SART and OSC-TV were able to maintain a good image quality with limited angle reconstruction. In the micro-CT bar pattern phantom results, the top three best-performing algorithms are OS-SART, OSC-TV, and MLEM. In the anolis sagrei cadaver results, the best algorithms are OSC-TV, MLEM, and OS-SART. Conclusion: In the iterative reconstruction algorithms tested, MLEM, OS-SART and OSC-TV have superior performance than other algorithms. Since their performances in image quality vary between imaged objects, the choice of reconstruction algorithm may be task-dependent and requires further investigation. This study provides future studies with a framework of testing and evaluation for determining the ideal iterative reconstruction method in the CBCT system development.

The emerging and competitive environment in the space technology requires the improvements in the capability of aerodynamic vehicles. This leads to the analysis in drag reduction of the vehicle along with the minimized heat transfer rate. Using forward facing solid aerospike is the simplest way among the existing drag reduction methodologies for hypersonic blunt cone bodies. But the flow oscillations associated with this aerospike makes it difficult to implement. When analyzing this flow, it can be understood that this oscillating flow can be compared to conical cavity flow. Therefore in the spiked flows, it is decided to implement the technique used in reducing the flow oscillation of the cavities. Based on this method the shallow conical cavity flow generated by the aerospike fixed ahead of a 120o blunt cone body is fissured as multiple cavities by so many disks formed from 10o cone. Now the deep conical cavities had the length to mean depth ratio of unity; this suppresses the unnecessary oscillations of the shallow cavity. The total length of the telescopic aerospike is fixed as 100mm. And one another conical tip plain aerospike of same length is designed for comparing the telescopic spike’s performance at hypersonic flow Mach numbers of 5.75 and 7.9. A three component force balance system capable of measuring drag, lift and pitching moment is designed and mounted internally into the skirt of the model. Drag measurement is done for without spike, conical tip plain spiked and telescopic spiked blunt cone body. The three configurations are tested at different angles of attack from 0 to 10 degree with a step of 2. A discrete iterative deconvolution methodology is implemented in this research work for obtaining the clean drag history from the noisy drag accelerometer signal. The drag results showed the drag reduction when compared to the without spike blunt cone body. When comparing to the plain spiked, the telescopic spiked blunt cone body has lesser drag at higher angles of attack. Heat transfer measurements are done over the blunt cone surface using the Platinum thin film gauges formed over the Macor substrate. These results and the flow visualization give better understanding of the flow and the heat flux rate caused by the flow. The enhancement in the heat flux rate over the blunt cone surface is due to the shock interaction. And in recirculation region the heat flux rate is very much lesser when compared to without spike blunt cone body. It is observed that the shock interaction in the windward side is coming closer towards the nose of the blunt cone as the angle of attack increases and the oscillation of the oblique shock also decreases. Schlieren visualization showed that there is dispersion in the oblique shock, particularly in the leeward side. In the telescopic spike there are multiple shocks generated from each and every disk which coalesces together to form a single oblique shock. And the effect of the shock generated by the telescopic spike is stronger than the effect of the shock generated by the conical tip plain spike.

The emerging and competitive environment in the space technology requires the improvements in the capability of aerodynamic vehicles. This leads to the analysis in drag reduction of the vehicle along with the minimized heat transfer rate. Using forward facing solid aerospike is the simplest way among the existing drag reduction methodologies for hypersonic blunt cone bodies. But the flow oscillations associated with this aerospike makes it difficult to implement. When analyzing this flow, it can be understood that this oscillating flow can be compared to conical cavity flow. Therefore in the spiked flows, it is decided to implement the technique used in reducing the flow oscillation of the cavities. Based on this method the shallow conical cavity flow generated by the aerospike fixed ahead of a 120o blunt cone body is fissured as multiple cavities by so many disks formed from 10o cone. Now the deep conical cavities had the length to mean depth ratio of unity; this suppresses the unnecessary oscillations of the shallow cavity. The total length of the telescopic aerospike is fixed as 100mm. And one another conical tip plain aerospike of same length is designed for comparing the telescopic spike’s performance at hypersonic flow Mach numbers of 5.75 and 7.9. A three component force balance system capable of measuring drag, lift and pitching moment is designed and mounted internally into the skirt of the model. Drag measurement is done for without spike, conical tip plain spiked and telescopic spiked blunt cone body. The three configurations are tested at different angles of attack from 0 to 10 degree with a step of 2. A discrete iterative deconvolution methodology is implemented in this research work for obtaining the clean drag history from the noisy drag accelerometer signal. The drag results showed the drag reduction when compared to the without spike blunt cone body. When comparing to the plain spiked, the telescopic spiked blunt cone body has lesser drag at higher angles of attack. Heat transfer measurements are done over the blunt cone surface using the Platinum thin film gauges formed over the Macor substrate. These results and the flow visualization give better understanding of the flow and the heat flux rate caused by the flow. The enhancement in the heat flux rate over the blunt cone surface is due to the shock interaction. And in recirculation region the heat flux rate is very much lesser when compared to without spike blunt cone body. It is observed that the shock interaction in the windward side is coming closer towards the nose of the blunt cone as the angle of attack increases and the oscillation of the oblique shock also decreases. Schlieren visualization showed that there is dispersion in the oblique shock, particularly in the leeward side. In the telescopic spike there are multiple shocks generated from each and every disk which coalesces together to form a single oblique shock. And the effect of the shock generated by the telescopic spike is stronger than the effect of the shock generated by the conical tip plain spike.

博士
國立臺灣科技大學
電子工程系
100
In buildings, efficient lighting systems and excellent design of interior natural light illumination can contribute to energy savings; meanwhile, natural light illumination systems have the potential to improve human health, mood, performance and productivity. Prismatic elements are widely used in natural light illumination systems for redirecting and collect daylight. Prismatic elements can be part of a daylight illuminate system located on the roof or façade of buildings and can be used as collectors to collect and guide daylight to reduce glare and save energy. An analysis of the distribution of the energy and ray-tracing can improve the performance of daylight guiding systems and aid in the design of natural light illumination systems. The characteristics of the light that emerges from the surface of a right-angled prism vary with the apex of the prism and the incident angle of the sunshine illuminating the surface of the prismatic daylight collector. Based on the principles of optics, this article presents a simple mathematical three dimensional matrix ray-tracing methodology through which a detailed intensity distribution of parallel light beam incident onto a right angled prism from different incident angles can be calculated precisely. The direction, concentration and distribution of intensity of the emerged light from the parallel light incident onto a surface of the right-angle prism, as well as daylight illuminate on a prismatic collector are precisely calculated. The detailed calculation of the emerged light re-incident onto the adjacent prism or emerged out of the right angled prismatic element with a 45° apex angle presented that most of daylight are directly emerged out and are confined in some directions at earlier morning and afternoon; the emerged light re-incident into the adjacent prism at noon around. This paper also investigates the effect of the apex angle of a right-angled prismatic collector on the performance of the collector using this matrix ray tracing model and the edge principle. It was found that the majority of the light emerges from the hypotenuse of the right-angled prism when sunshine is incident on the surface of the prismatic daylight collector; furthermore, the distribution of the light can be shifted by changing the apex of the right-angled prismatic collector. The direct illumination level of the light emerging from the hypotenuse decreases as the apex of the right-angled prism is increased. The intensity distribution of the majority of the light emerging from the hypotenuse of a right-angled prism can be used to guide the design of natural light illumination systems and enhance their performance. The percentage of light emerging from the hypotenuse decreases with the number of prismatic elements because the relative area of the emerging light that reaches the adjacent prism increases with the number of prismatic elements. The analysis of the relative area of the emerging light that reaches the adjacent prism according to the edge ray principle shows that the total area is constant when the number of prismatic elements is greater than 10; an economical prismatic daylight collector can be realized with less material due to the larger number of smaller prisms with the same apex. This detailed calculation model of parallel light beam incident to a prismatic element can be applied to the hybrid natural light illumination system as well as to the prism-relative solar illumination system for the improvement of efficiency. This paper proposes a model of a natural light illumination system that would improve the efficiency of solar energy use. This model is composed of a prismatic daylight collector, a reflector for re-directing daylight into the room and a diffuse reflector for indoor illumination. The prismatic daylight collector and the daylight canopy not only decrease the discomfort of glare but also collect daylight for the natural lighting system.

Digital tomosynthesis (DTS) is a quasi-three-dimensional (3D) imaging technique which reconstructs images from a limited angle of cone-beam projections with shorter acquisition time, lower imaging dose, and less mechanical constraint than full cone-beam CT (CBCT). However, DTS images reconstructed by the conventional filtered back projection method have low plane-to-plane resolution, and they do not provide full volumetric information for target localization due to the limited angle of the DTS acquisition.

This dissertation presents the optimization and clinical implementation of image guided radiation therapy using limited-angle projections.

A hybrid multiresolution rigid-body registration technique was developed to automatically register reference DTS images with on-board DTS images to guide patient positioning in radiation therapy. This hybrid registration technique uses a faster but less accurate static method to achieve an initial registration, followed by a slower but more accurate adaptive method to fine tune the registration. A multiresolution scheme is employed in the registration to further improve the registration accuracy, robustness and efficiency. Normalized mutual information is selected as the criterion for the similarity measure, and the downhill simplex method is used as the search engine. This technique was tested using image data both from an anthropomorphic chest phantom and from head-and-neck cancer patients. The effects of the scan angle and the region-of-interest size on the registration accuracy and robustness were investigated. The average capture ranges in single-axis simulations with a 44° scan angle and a large ROI covering the entire DTS volume were between -31 and +34 deg for rotations and between -89 and +78 mm for translations in the phantom study, and between -38 and +38 deg for rotations and between -58 and +65 mm for translations in the patient study.

Additionally, a novel limited-angle CBCT estimation method using a deformation field map was developed to optimally estimate volumetric information of organ deformation for soft tissue alignment in image guided radiation therapy. The deformation field map is solved by using prior information, a deformation model, and new projection data. Patients' previous CBCT data are used as the prior information, and the new patient volume to be estimated is considered as a deformation of the prior patient volume. The deformation field is solved by minimizing bending energy and maintaining new projection data fidelity using a nonlinear conjugate gradient method. The new patient CBCT volume is then obtained by deforming the prior patient CBCT volume according to the solution to the deformation field. The method was tested for different scan angles in 2D and 3D cases using simulated and real projections of a Shepp-Logan phantom, liver, prostate and head-and-neck patient data. Hardware acceleration and multiresolution scheme are used to accelerate the 3D estimation process. The accuracy of the estimation was evaluated by comparing organ volume, similarity and pixel value differences between limited-angle CBCT and full-rotation CBCT images. Results showed that the respiratory motion in the liver patient, rectum volume change in the prostate patient, and the weight loss and airway volume change in the head-and-neck patient were accurately estimated in the 60° CBCT images. This new estimation method is able to optimally estimate the volumetric information using 60-degree projection images. It is both technically and clinically feasible for image-guidance in radiation therapy.

Dissertation

碩士
國立中央大學
太空科學研究所
99
The subsolar standoff distance of the Earth’s magnetopause is an important parameter in studying interactions between the solar wind and the magnetosphere. Its value is mainly controlled by the north-south component (Bz) of the interplanetary magnetic field (IMF) and solar wind dynamic pressure (Dp). Recent studies have found that the subsolar standoff distance is large for small cone angle of the IMF, that is, the orientation of the IMF is almost parallel to the Sun-Earth line. However, relationship between the subsolar standoff distance and cone angle under different IMF Bz and Dp conditions have not been comprehensively studied. With a large set of subsolar magnetopause crossings identified from the THEMIS data and their corresponding solar wind conditions obtained from the OMNI data, we are able to bin the magnetopause crossings in four categories by the southward and northward polarities of the IMF, and large and small Dp. Here we find that the relationship between the subsolar standoff distance and cone angle changes with IMF Bz and Dp. The smallest subsolar standoff distance occurs when the cone angle is near 90 degrees in the category of southward IMF and high Dp.

Indiana University-Purdue University Indianapolis (IUPUI)
Introduction: In order to successfully treat an infected root canal system (RCS), it is required to locate all root canals and have an access path to the apex of each canal. This can be challenging in teeth with pulp canal obliteration (PCO), often leading to increased chair time and increased risk of iatrogenic errors. Guided endodontic access (GEA) combines information from a cone-beam computed tomography (CBCT) scan with an intra-oral scan to create a stent. GEA stents with or without fixation pins have been shown to be successful in accurately negotiating a RCS with PCO. Objective: Compare the degree of deviation and difference in 3D offset at the base to apical tip of the drill from the designed access path when a GEA stent with and without pin fixation is used to access tooth #8 with PCO. Materials and Methods: A 3-D printed maxillary model of an anonymous patient had a GEA stent designed using coDiagnonstiX software. The stent extended from tooth #3 to tooth #14 with the guide sleeve over tooth #8. Tooth #8 with no calcification, calcification to the cervical third, and calcification to the middle third of the RCS were designed in the coDiagnostiX software. Tooth #8 will be accessed using a 1.3 mm drill that fits a 1.3 mm sleeve used for both access and pin fixation. 15 of the 30 GEA samples will utilized pin fixation, while the other 15 samples did not utilize pin fixation. Following GEA in all 30 samples a CBCT was taken of each sample. Each post-operative CBCT was aligned with the pre-operative CBCT in the coDiagnostiX software. The coDiagnostiX software was able to calculate the degree of deviation and difference in 3D offset between the base and apical tip of the drill during GEA. Paired t-tests were used to test each group for significant differences in 3D offset between base and tip. Two-way ANOVA was used to evaluate the effects of pin fixation and calcification on the degree of deviation and the deviation of 3D offset of the entry point and tip. Results: There was a significant interaction between use of pin fixation and calcification level on the degree of deviation of GEA. GEA with pin fixation had a significantly larger degree of deviation than GEA without pin fixation with calcification extending to the middle third of the RCS. GEA with and without pin fixation did not have a significant difference when calcification extended to the cervical third of the RCS or no calcification was present. There was a significant interaction between use of pin fixation and calcification level on 3D offset difference. GEA with pin fixation had a significantly larger 3D offset difference than GEA with no pin fixation for calcification in the middle third of the RCS. For GEA with and without pin fixation there was no significant difference when calcification extended to the cervical third of the RCS or no calcification was present. Conclusion: The use of pin fixation did not result in a decrease of degree of deviation or difference in 3D offset during GEA access. It can be concluded that the use of pin fixation is not necessary for GEA of teeth with PCO when a full dentition is present to provide stability and retention of the stent.

碩士
國立臺灣大學
化學工程學研究所
105
Due to its potential applications in biotechnology, ion current rectification (ICR) arising from the asymmetric nature of ion transport in a nanochannel has drawn the attention of researchers in various fields. In the former, the influences of the cone angle, surface charge density, and bulk salt concentration on this behavior are investigated, and mechanisms proposed to explain the results obtained. We show that if the cone angle is enlarged by fixing the nanopore tip radius and raising its base radius, the ICR ratio has a local maximum. This behavior may not present if the cone angle is enlarged by fixing the nanopore base radius and raising its tip radius. This ratio also has a local maximum as the surface charge density varies and the larger the cone angle the higher the surface charge density at which the local maximum in the ICR ratio occurs. In the latter, to assess the possibility of energy harvesting through reverse electrodialysis (RED), we consider the electrokinetic behavior of the ion transport in a pH-regulated conical nanopore connecting two large reservoirs having different bulk salt concentrations. In particular, the influences of the ion diffusion direction, the solution pH, and the bulk concentration ratio on that behavior are examined in detail, and the underlying mechanisms discussed. We show that the geometrically asymmetric nature of the nanopore yields profound and interesting phenomena arising mainly from the distribution of ions in its interior. We show that a power of 18.3 pW can be generated, and the maximum power efficiency of 0.53 achieved from a PET nanopore

X-ray micro computed tomography (CT) is a useful tool for imaging 3-D internal structures. It has many applications in geophysics, biology and materials science. Currently, micro-CT’s capability are limited due to validity of assumptions used in modelling the machines’ physical properties, such as penumbral blurring due to non-point source, and X-ray refraction. Therefore many CT research in algorithms and models are being carried out to overcome these limitations. This thesis presents methods to improve image resolution and noise, and to enable material property estimation of the micro-CT machine developed and in use at the ANU CTLab. This thesis is divided into five chapters as outlined below. The broad background topics of X-ray modelling and CT reconstruction are explored in Chapter 1, as required by later chapters. It describes each X-ray CT component, including the machines used at the ANU CTLab. The mathematical and statistical tools, and electromagnetic physical models are provided and used to characterise the scalar X-ray wave. This scalar wave equation is used to derive the projection operator through matter and free space, and basic reconstruction and phase retrieval algorithms. It quantifies the four types of X-ray interaction with matter for X-ray energy between 1 and 1000 keV, and presents common assumptions used for the modelling of lab based X-ray micro-CT. Chapter 2 is on X-ray source deblurring. The penumbral source blurring for X-ray micro-CT systems are limiting its resolution. This chapter starts with a geometrical framework to model the penumbral source blurring. I have simulated the effect of source blurring, assuming the geometry of the high-cone angle CT system, used at the ANU CTLab. Also, I have developed the Multislice Richardson-Lucy method that overcomes the computational complexity of the conjugate gradient method, while produces less artefacts compared to the standard Richardson-Lucy method. Its performance is demonstrated for both simulated and real experimental data. X-ray refraction, phase contrast and phase retrieval (PR) are investigated in Chapter 3. For weakly attenuating samples, intensity variation due to phase contrast is a significant fraction of the total signal. If phase contrast is incorrectly modelled, the reconstruction would not correctly account the phase contrast, therefore it would contribute to undesirable artefacts in the reconstruction volume. Here I present a novel Linear Iterative multi-energy PR algorithm. It enables material property estimation for the near field submicron X-ray CT system and reduces the noise and artefacts. This PR algorithm expands the validity range in comparison to the single material and data constrained modelling methods. I have also extended this novel PR algorithm to assume a polychromatic incident spectrum for a non-weakly absorbing object. Chapter 4 outlines the space filling X-ray source trajectory and reconstruction, on which I contributed in a minor capacity. This space filling trajectory reconstruction have improved the detector utilisation and reduced nonuniform resolution over the state-of-the-art 3-D Katsevich’s helical reconstruction, this patented work was done in collaboration with FEI Company. Chapter 5 concludes my PhD research work and provides future directions revealed by the present research.