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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

A Synthesis of Geometry and Light

Mukesh Jain, Prakhyaa 19 January 2021 (has links)
The poetics of an architecture of a moment is explored through design of a contemplative room (wherin the geometric transformation of a cubic base to a cone) demonstrates the rhythmn and proportion of the construction of the room and the relative motion of the sun in the space. The relationship of the sun rays on the walls of the room passing through a reflecting pool are shown using demonstrative and constructive means of descriptive geometry as both the design generator and poetic expression.The composition of the buildings reveals the play of light on form. / Master of Architecture / An exploration to understand the relationship of architecture and the material sensible world. The work seeks to reveal that through the tangible architectural strategies of form, structure, material and light, the intangible qualities of architecture are defined.
202

Controlling Object Heat Release Rate using Geometrical Features

Kraft, Stefan Marc 08 June 2017 (has links)
An experimental study was conducted to determine the effect of complex geometries on the burning rate of materials made using additive manufacturing. Controlling heat release rate has applicability in limiting fire hazards as well as for designing fuels for optimal burning rate. The burning rate of a structure is a function of the material properties as well as the airflow through it, which is dictated by the geometry. This burning rate is generally proportional to the porosity for objects in which the flow is limited by the path constriction. The relations between porosity and burning rate are well studied for wood cribs, which are layers of wood sticks. Crib and other objects with various geometric features were constructed of ABS plastic and coal powder using additive manufacturing processes. A cone calorimeter using oxygen calorimetry was used to measure the heat release rate of the crib specimens. Within the flow limited burning regime, the burning rate of an object is proportional to the porosity factor. Porosity factors calculated from a 1-D theoretical burn rate model as well as from two empirical models were found to correlate the heat release rate results for the crib samples. The heat release rate results of the complex geometries generally correlated to the same porosity factor; however, the model was modified to account for differences between regularly shaped cribs and objects with different sized flow areas. Using the empirical models provides good correlation for the crib burning data and gives a clearer delineation between the flow-limited and surface area controlled regimes. / Master of Science
203

Studies in Conical Form

Randolph, Joel Howard 02 August 2018 (has links)
The design of a conical room for experiencing a fleeting moment was developed through a series of demonstrative studies. The desired effect of a momentary appearance of a ray of light striking a reflective surface in a room based on the predicted relative position of the sun at set times determined the form, shape, proportions, and surface conditions of the room. / Master of Architecture
204

Evaluating the potential for cone beam CT to improve the suspected scaphoid fracture pathway: InSPECTED - A single-centre feasibility study

Snaith, Beverly, Harris, M., Hughes, J., Spencer, N., Shinkins, B., Tachibana, A., Bessant, G., Robertshaw, S. 01 April 2022 (has links)
Yes / The suspected scaphoid fracture remains a diagnostic conundrum with over-treatment a common risk-averse strategy. Cross-sectional imaging remains the gold standard with MRI recommended but CT used by some because of easier access or limited MRI availability. The aim of this feasibility study was to evaluate whether cone beam computed tomography (CBCT) could support early diagnosis, or exclusion, of scaphoid fractures. Patients with a suspected scaphoid were recruited fracture between March and July 2020. All underwent a 4-view X-ray. If this examination was normal, they were immediately referred for a CBCT scan of the wrist. Those with a normal scan were discharged to research follow-up at 2 and 6-weeks. 68 participants were recruited, 55 had a normal or equivocal X-ray and underwent CBCT. Nine additional radiocarpal fractures (16.2%) were demonstrated on CBCT, the remainder were discharged to research follow-up. Based on the 2-week and 6-week follow up three patients (4.4%) were referred for MRI to investigate persistent symptoms with no bony injuries identified. CBCT scans enabled a rapid pathway for the diagnosis or exclusion of scaphoid fractures, identifying other fractures and facilitating early treatment. The rapid pathway also enabled those with no bony injury to start rehabilitation, suggesting that patients can be safely discharged with safety-net advice following a CBCT scan.
205

Incremental and decremental L- and M-cone driven ERG responses: II. Sawtooth stimulation.

Kremers, Jan, Pangeni, G., Tsaousis, K.T., McKeefry, Declan J., Murray, I.J., Parry, Neil R.A. 04 1900 (has links)
No / L- and M-cone driven on- and off- ERG responses and their interactions were examined using full field stimuli with sawtooth temporal profiles. The effects of temporal frequency and contrast were studied. ERG recordings were obtained from 21 trichromatic, 1 protanopic, and 1 deuteranopic subjects. ERGs to L-cone increments and decrements resembled those to M-cone decrements and increments, respectively (i.e., of the opposite polarity). Temporal frequency and contrast had little effect on the implicit times. All response components varied linearly with contrast. When stimulated simultaneously, the responsivities of most components were larger for counterphase than for inphase modulation. The retinal processing leading to an ERG response is reversed for L- and M-cone driven responses.
206

The Spatial Properties of L- and M-Cone Inputs to Electroretinograms That Reflect Different Types of Post-Receptoral Processing

Jacob, M.M., Pangeni, G., Gomes, B.D., Souza, G.S., Da Silva Filho, M., Silveira, L.C.L., Maguire, John, Parry, Neil R.A., McKeefry, Declan J., Kremers, Jan 18 March 2015 (has links)
Yes / We studied the spatial arrangement of L- and M-cone driven electroretinograms (ERGs) reflecting the activity of magno- and parvocellular pathways. L- and M-cone isolating sine wave stimuli were created with a four primary LED stimulator using triple silent substitution paradigms. Temporal frequencies were 8 and 12 Hz, to reflect cone opponent activity, and 30, 36 and 48 Hz to reflect luminance activity. The responses were measured for full-field stimuli and for different circular and annular stimuli. The ERG data confirm the presence of two different mechanisms at intermediate and high temporal frequencies. The responses measured at high temporal frequencies strongly depended upon spatial stimulus configuration. In the full-field conditions, the L-cone driven responses were substantially larger than the full-field M-cone driven responses and also than the L-cone driven responses with smaller stimuli. The M-cone driven responses at full-field and with 70° diameter stimuli displayed similar amplitudes. The L- and M-cone driven responses measured at 8 and 12 Hz were of similar amplitude and approximately in counter-phase. The amplitudes were constant for most stimulus configurations. The results indicate that, when the ERG reflects luminance activity, it is positively correlated with stimulus size. Beyond 35° retinal eccentricity, the retina mainly contains L-cones. Small stimuli are sufficient to obtain maximal ERGs at low temporal frequencies where the ERGs are also sensitive to cone-opponent processing
207

A dim view of M-cone onsets

Parry, Neil R.A., McKeefry, Declan J., Kremers, Jan, Murray, I.J. 03 1900 (has links)
No / We investigated the brightness (i.e., perceived luminance) of isolated L- and M-cone pulses to seek a perceptual correlate of our previous reports that M-on electroretinograms resemble L-off responses, implying the operation of post-receptoral opponent processing. Using triple silent substitutions, cone increments were generated in a 4-primary ganzfeld, masked by random positive or negative luminance bias. The results show that M-cone increments decrease in brightness, while L-cone increments increase. These differences became smaller as field size reduced; this was not eccentricity or area dependent. We speculate about early retinal input into brightness perception.
208

Jämförelse av odränerad skjuvhållfasthet mellan CPT-sondering och fallkonförsök på Uppsalalera

Svensson, Axel January 2017 (has links)
The knowledge about the shear strength of a soil is important because it is a key parameter that is used in many calculations in construction engineering. Some examples of what’s possible to calculate are slope stability, the soil pressure against retaining walls and the carrying capacity of building foundations. Great economic losses or, in the worst case scenario the risk for human lives, could be the result if the geotechnical properties of the soil are ignored. This report considers the undrained shear strength of clay from Uppsala. There are different methods based on empirical experiences which are used to determine the undrained shear strength of a clay. In this project the methods and the results in undrained shear strength are compared between CPT-probing, which is carried out in-situ, and the drop cone test which is done in a laboratory. The reason for this comparison is that they usually don’t show the same results.The tests had already been made before this project started and therefore it is only the comparison of the results between the methods that has been done. The comparison was done by creating charts in Excel where the results from CPT and the drop cone test from was put together from the same point. The shear strength values from the methods were also statistically analysed with a t-test to see if they show the same hypothetical expected value with 95 % significance in every test point / Kunskap om skjuvhållfastheten är viktig då den används för beräkningar inom byggoch anläggningsbranschen. Exempel på vad som kan beräknas är släntstabilitet, jordtrycket mot en spont eller bärförmågan hos en byggnadsgrund. Stora ekonomiska förluster och i värsta fall fara för människoliv kan bli resultatet om jordens geotekniska egenskaper ignoreras. Denna rapport tar upp den odränerade skjuvhållfastheten i Uppsalalera. Det finns olika metoder som bygger på empiriska erfarenheter som kan användas för att ta reda på den odränerade skjuvhållfastheten i lera. I föreliggandeprojekt jämförs metoderna och resultaten i odränerad skjuvhållfasthet mellan CPT-sondering som utförs in-situ och fallkonförsök som utförs på lerprover i ett laboratorium. Anledningen till studien är att metoderna inte alltid ger samma mätvärden. Undersökningarna utfördes innan projektet började. Jämförelsen har gjorts genom den statistiska jämförelsen t (student)-test. Resultatet från t-testet visar att skjuvhållfasthetsvärdena från CPT respektive fallkonförsöken från samma undersökningspunkt och från samma nivå har samma hypotetiska förväntade värde på 95 % signifikansnivå. Genom sammanställda grafer syns att metoderna i de flesta fall överensstämmer till ett djup på minst 20 m.
209

Geração de semigrupos por operadores elípticos em L POT. 2 (OMEGA) e C INF. 0 (OMEGA) / Generations of semigroups for elliptic operators in \'L POT. 2\' (\'OMEGA\') and \'C IND. 0(\'OMEGA\')

Leva, Pedro David Huillca 18 March 2014 (has links)
Neste trabalho estudaremos a geração do semigrupos por operadores elípticos em dois espaços. Em primeiro lugar estudaremos a geração de semigrupo no espaço \'L POT.2\' (\'OMEGA\') por operadores elípticos de ordem 2m com \'OMEGA\' suficientemente regular. Mais precisamente, se \'OMEGA\' é um domínio limitado com \'PARTIAL OMEGA\' de classe \'C POT. 2m,\' L (x;D) = \'SIGMA\' / [\'alpha\'] \'< ou =\' \'a IND. alpha\' (x) \'D POT. alpha\' é um operador diferencial elíptico de ordem 2m, com \'a IND. alpha\' \'PERTENCE\' \' \'C POT.j\' (\'OMEGA\'), j = max {0, [\'alpha\'] - m}, e A : D(A) \'ESTÁ CONTIDO\' EM \'L POT. 2 (\'OMEGA\') \'SETA\' \' L POT. 2 (\'OMEGA\') é o operador linear dado por D(A) = \'H POT. 2m\' (\'OMEGA\') \'H POT. m INF. 0\' (\'OMEGA\'), (Au)(x) = L (x;D)u; então -A gera um \'C IND. 0\'-semigrupo holomorfo em \'L POT.2\' (\'OMEGA\'). ). Em segundo lugar estudaremos a geração de semigrupo em \'C IND. 0\'(\'OMEGA\") = ) = {u \'PERTENCE A\' C (\'OMEGA\' \'BARRA\") : u[\'PARTIAL omega\' = 0} por operadores elípticos de ordem 2 com \'OMEGA\' satisfazendo uma propriedade geométrica. Mais precisamente, se \'OMEGA\' ESTA CONTIDO EM\' \'R POT. n\' (n \'> ou =\' 2) é um domínio limitado que satisfaz a condição de cone exterior uniforme, L é o operador Lu := - \\\\SIGMA SUP n INF. i,j = 1\' \'a IND. ij \'D IND. ij u + \'\\SIGMA SUP. n IND. j=1 \'b IND. j\' u + cu com coeficientes reais \'a IND. ij\' , \'b IND. j\' , c que satisfazem \'b IND. j \' \'PERTENCE A\' \'L POT. INFTY\' (\'OMEGA\') , j = 1, ..., n, c \'PERTENCE A \' \'L POT> INFTY\' (OMEGA), c \'> ou =\' 0, \'a IND. ij\' \'PERTECE A\' C(\' OMEGA BARRA)\' \' INTERSECCAO\' \'L POT. INFTY\' (OMEGA),e \'A IND. 0\' é parte de L em \'C IND. 0\' (\"OMEGA\'), isto é, D(\'A IND. 0\') = {u \'PERTENCE A\' \'C IND. 0\' (\'OMEGA\') \'INTERSECÇÂO\' \'W POT. 2, n INF. loc\' (\'OMEGA\') : Lu \'PERTENCE A\' \'C IND. 0\' (\'OMEGA\')\' \'A IND. 0\' u = Lu, então -\'A IND. 0\' gera um \'C IND. 0-semigrupo holomorfo limitado em \'C IND. 0\' (\'OMEGA\') / In this work we study the generation of semigroups by elliptic operators in two spaces. Firstly we study the generation of semigroup in the space \'L POT. 2\' (OMEGA) for elliptic operators of order 2m with \'OMEGA\' regular domain. More precisely, if \'OMEGA\' is a bounded domain with \\PARTIAL OMEGA\' \'IT BELONGS\' \'C POT. 2m\', L (x, D) = \\ sigma INF.ALPHA \'> or =\' 2m, \'a IND. alpha\' ( x) \'D POT alpha\' is an elliptic differential operator of order 2m, with \'a IND. alpha\' \' \'IT BELONGS\' \'C POT. j\' (OMEGA), j = max , and A : D (A) \'THIS CONTAINED\' \'L POT. 2\' (OMEGA) \'ARROW\' \'L POT. 2\' (OMEGA) is linear operator given or D(A) = \'H POT. 2m\' (OMEGA) \'INTERSECTION\' \'H POT. m INF. 0 (OMEGA) (Au) (x) = L (x,D) u then -A generates a holomorphic \'C IND. 0\'-semigroup in \'L POT. 2\'.(OMEGA). Secondly we study the generation of semigroup in \'C IND. 0\' (OMEGA) = {u \'IT BELONGS\' (c INF. O\' (OMEGA BAR) : \'u [IND. \\partial omega\' = 0} for elliptic operators of second order with \'OMEGA\' satisfying a geometric property. That is, if \'OMEGA\' \'IT BELONGS\' \'R POT. n\' (n > or = 2) is a bounded domain that satisfies the uniform exterior cone condition, L is the elliptic operator given by Lu : = - \\SIGMA SUP. n INF. i,j = 1\' \'a IND. i, j\' \'D IND. ij \' u + \\SIGMA SUP n INF. j=1\' \'b IND j D IND j\' u + cu with real coefficients \'a IND. ij, \'b IND. j\' , c satisfying \'b ind. j\' \'IT BELONGS\' \' L POT. INFTY\' (omega), j = 1, ..., n, c \'it belongs\' \'L POT. INFTY\' (OMEGA), \'c > or =\' 0, \'\'a IND. ij \'IT BELONGS\' C (OMNEGA BAR) \'INTERSECTION\' (OMEGA), and \'A IND. 0\' is part of L in \'C IND. 0\'(OMEGA), that is, D (\'A IND. 0\') = {u \'IT BELONGS\' \'C IND. 0\' (OMEGA) INTERSECTION \'W POT. 2, n IND. loc (OMEGA)} \'A IND. 0u\' = Lu, then - \'A IND. 0\' generates a bounded holomorphic \'C IND. 0\'-semigroup on \'C IND. 0\' (OMEGA)
210

Avaliação da tomografia computadorizada Cone Beam como método de proservação de lesões periapicais após o tratamento endodôntico em pacientes com fissura labiopalatina / Evaluation of cone beam computed tomography as a method of follow-up of periapical lesions after endodontic treatment in patient with cleft lip and palate

Dextre, Tulio Lorenzo Olano 29 June 2012 (has links)
O objetivo deste trabalho foi comparar a eficácia da Tomografia Computadorizada Cone Beam e a Radiografia Periapical como métodos de proservação de lesões periapicais após o tratamento endodôntico. Foram avaliadas no estudo Radiografias e Tomografias de 1.462 indivíduos com fissura labiopalatina no Hospital de Reabilitação de Anomalias Craniofaciais Universidade de São Paulo, que compareceram para o tratamento endodôntico entre os anos 2009 e 2011. De acordo com os critérios de inclusão, foram selecionados 46 dentes unirradiculares com lesão periapical, os quais foram divididos nos grupos: avaliação Radiográfica (Grupo I) e avaliação Tomográfica (Grupo II). Os dados foram analisados por meio do escore PAI para as alterações periapicais encontradas. Nos resultados observou-se que houve diferença estatisticamente significativa nos grupos estudados. Em 34 casos os escores atribuídos às Tomografias dos dentes avaliados foram maiores do que os escores atribuídos às Radiografias Periapicais dos mesmos dentes avaliados, comprovando a maior precisão da Tomografia Computadorizada Cone Beam. Desta forma, a análise dos resultados obtidos neste trabalho permite constatar que a Tomografia Computadorizada Cone Beam é mais eficaz na proservação de lesões periapicais do que a Radiografia Periapical após o tratamento endodôntico em pacientes com fissura labiopalatina. / The aim of this study was to compare the effectiveness of Cone Beam Computed Tomography and periapical radiography as a follow-up method of periapical lesions after endodontic treatment. We evaluated in the study radiographs and tomography scans of 1,462 individuals with cleft lip and palate at the Hospital of Rehabilitation of Craniofacial Anomalies - University of Sao Paulo who came for treatment endodontic between the years 2009 and 2011. According to inclusion criteria were selected 46 single-rooted teeth with periapical lesions, which were divided into groups radiographic evaluation (Group I) and tomographic evaluation (Group II). Data were analyzed using the PAI score for periapical changes found. The results were observed that statistically significant differences in the groups studied. In 34 cases the CT scores attributed to the teeth evaluated were higher than the scores attributed to the radiographs of same teeth evaluated, demonstrating the greater precision of Cone Beam Computed Tomography. Thus, analysis of results obtained in this work demonstrates that the Cone Beam Computed Tomography is more effective in follow-up of periapical lesions than periapical radiography after endodontic treatment in patients with cleft lip and palate.

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