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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.
41

Identification of Force Coefficients in Two Squeeze Film Dampers with a Central Groove

Seshagiri, Sanjeev 2011 May 1900 (has links)
Squeeze Film Dampers (SFD) provide viscous damping in rotor bearing systems to reduce lateral vibration amplitudes and to isolate mechanical components. Aircraft engine shafts, often supported on roller bearings, operate at high rotational speeds and are susceptible to large amplitude shaft whirl due to rotor imbalance. SFDs aid to reduce such large whirl amplitudes while also eliminating rotor instabilities. he current work quantifies experimentally the forced performance of two parallel squeeze SFDs separated by a central groove. Force coefficients are identified in a specialized SFD test rig constructed to undergo similar operating and loading conditions as in jet engines. Of interest is to quantify the effect of a central feed groove on the forced performance of SFDs and to validate predictions from a computational tool. The test rig comprises of an elastically supported bearing structure and one of two journals. Tests are conducted on two open ends SFDs, both with diameter D and nominal radial clearance c; each damper with two parallel film land lengths L= 1/5 D and 2L, separated by a feed groove of width L and depth 3/4 L. ISO VG 2 grade lubricant oil flows into the central groove via 3 orifices, 120 degrees apart, and then through the film lands to finally exit to ambient. In operation, a static loader pulls the bearing to various static off center positions with respect to the stationary journal, and electromagnetic shakers (2,200 N) excite the test system with single frequency loads over a frequency range to generate rectilinear, circular and elliptical orbits with specified motion amplitudes. A frequency domain method identifies the SFD mechanical parameters, viz., stiffness, damping, and added mass coefficients. The long damper generates 7 times more direct damping and 2 times more added mass compared to the short length damper. The damping coefficients are sensitive to the static eccentricity (up to 50 percent c) while showing lesser dependency on the amplitude of whirl motion (up to 20 percent c). On the other hand, added mass coefficients are nearly constant with static eccentricity and decrease with higher amplitudes of motion. The magnitudes of identified cross-coupled coefficients are insignificant for all imposed operating conditions for either damper. Large dynamic pressures recorded in the central groove demonstrate the groove does not isolate the film lands by merely acting as a source of lubricant, but contributes to the generation of large added mass coefficients. The recorded dynamic pressures in the film lands and central groove do not evidence lubricant vapor or gas cavitation for the tested static eccentricities and amplitudes of motion. The direct damping coefficients for both dampers are independent of excitation frequency over the frequency range of the tests. Predictions derived from a novel SFD computational tool that includes flow interactions in the central groove and oil supply orifices agree well with the experimental force coefficients for both dampers. The current work advances the state of the art in SFDs for jet engines.
42

'... and I feel good!' : the relationship between body-movement, pleasure and groove in music

Witek, Maria January 2013 (has links)
In many musical cultures, people synchronise their bodies to the rhythmic patterns of the music, and such embodied engagements are one of the most overtly enjoyable forms of musical appreciation. However, the ways in which rhythmic structure, body-movement and pleasure are related remains unclear. The present thesis directs a broadly psychological, yet multi-methodological and interdisciplinary, approach towards this relationship, centring on the rhythmic structure of syncopation in groove-based funk music. Through perceptual experiments, computational modelling, rating surveys, neuroimaging and motion-capture recording, syncopation was found to relate, in primarily negatively linear and inverted U-shaped ways, to finger-tapping performance, perceptions of stability, subjective desire to move and feelings of pleasure, neural activity in motor and reward areas, and force, synchrony and periodicity in body-movements. These relationships also depended on individuals’ musical training, dancing experience and groove familiarity. Ecological and embodied theories of perception and a phenomenology of groove provide a backdrop to the empirical findings, on the basis of which it is suggested that the different relationships between syncopation in groove and perceptual, subjective, neural and corporeal attributes interact in reciprocal ways. It is proposed that syncopation invites the body to physically enact the musical structure and directly participate in the rhythms of groove, due to the perceptual tension and ‘open spaces’ afforded by the perception of metric events in syncopation. In groove, body, mind and music extend into each other and this distributed musical process has affective significance. Since the physical pleasures of dancing to music are such a historically and culturally ubiquitous phenomenon, the empirical findings and theoretical proposals of this thesis make significant contributions towards a much-needed coupling of affective and embodied theories of music.
43

Time & Sväng i sång / Time & Groove in Singing

Andersson, Gustaf January 2011 (has links)
Syftet med studien är att få djupare insikt i sångpedagogers syn på Time och Sväng samt hur de didaktiskt arbetar med dessa aspekter. Det saknas mer omfattande forskning inom området. Med detta i behåll har jag för avsikt att få djupare insikt i frågeställningar som rör olika förhållningssätt till hur sångare kan öva upp Time och Sväng samt vad Time och Sväng innebär, generellt och i ett undervisningsperspektiv. Studien har som sin teoretiska utgångspunkt ett sociokulturellt perspektiv med fokus på hur människor använder olika redskap för att kommunicera med sin omgivning. För att få svar på mina frågor har använt mig av en halvstrukturerad intervjuform när jag samtalat med informanterna. Alla informanter i denna studie arbetar idag som sångpedagoger; två av dessa är mer inriktade på jazz medan de andra två är mer inriktade på populärmusik. Resultaten visar att alla informanter anser att Time och Sväng är otroligt viktigt i musik. Tillvägagångssättet för hur de hanterar Time och Sväng skiljer sig däremot något, vilket visar sig i deras användning av en variation av olika redskap för att träna, undervisa i samt lära sig Time och Sväng. / The purpose of this study is to attain a deeper insight in how vocal coaches view Time and Groove and in what way they use these aspects didactically. Extensive research in this area is lacking, only a few papers and research studies exist. With this in mind, my intention is to acquire a deeper insight in questions concerning various methods in how vocalists can develop their abilities in Time and Groove, and what Time and Groove, both generally and from an educational point of view, is. The theoretical starting point of this study is a socio-cultural perspective focused on how people use various tools to communicate. I have worked with the semi-structured interview method when speaking to the informants. The informants work as vocal teachers; two are primarily teaching jazz music, whereas the other two are more oriented towards pop music. The results demonstrate that all of the informants believe that Time and Groove in music is very important. Their approach on how to work with Time and Groove differ slightly, which can be seen in their use of a variety of tools for practicing, teaching and learning Time and Groove.
44

Livet på planeten sväng : En studie om hur folkmusiker och afromusiker kan uppleva sväng / Life on planet groove Life on planet groove   A study in how Swedish folk musicians and jazz/pop musicians can experience groove : A study in how Swedish folk musicians and jazz/pop musicians can experience groove

Johansson, Petrus January 2010 (has links)
Syftet med arbetet var att undersöka om det finns skillnader och likheter mellan afromusiker och folkmusiker beträffande hur de behandlar begreppet sväng. För att besvara syftet användes fyra forskningsfrågor; Hur skapas sväng? Vad fokuserar musiker på i skapandet av sväng? Finns det skillnader mellan afromusikerns och folkmusikerns uppfattning om sväng? Och i så fall hur skiljer sig uppfattningarna åt?   Undersökningen gjordes genom intervjuer av sex musiker; tre afromusiker och tre folkmusiker. Arbetet baseras på deras subjektiva åsikter samt på forskning och litteratur i ämnet.   I arbetet tas följande teman upp; pulsförhållning och rytm, fotstamp/takt, timing, dynamik och kommunikation/samspel. Det visade sig att det finns vissa skillnader och likheter mellan de båda genrerna och mina informanters uppfattning om sväng. I studien visar bland annat att; det kan skilja mellan genrerna hur musikerna förhåller sig till en puls för att skapa sväng. Det kan även skilja hur musikerna använder dynamik i spelet för att skapa sväng. Musikerna är dock eniga om rytmens/synkopers betydelse för sväng. / The purpose of this study is to acquire a better understanding of how folk musicians and jazz/pop musicians view the concept of groove. To answer this, four research questions were used;   How do we create groove? What does a musician focus on in the creation of groove? Are there differences between folk musicians’ and Afro-musicians’ opinions on groove? And if so, how do the opinions differ?   I have interviewed six musicians; three Swedish folk musicians and three Afro-musicians. The study is based on their opinions, in addition to research and literature in this subject.   The material is broken down into different themes; beat variations and rythm, beats, timing, dynamics and communication. The study demonstrated that there are certain differences and similarities between the two genres and the opinions of those interviewed on the subject. Among other things, the study showed that the musicians had different ways in relating to the beat, and different ways to apply dynamics in their music to achieve groove. The musicians are unanimous in their view of the importance of syncopations in relation to the beat.
45

Mesurer les habiletés de la population générale à percevoir et à se synchroniser à la pulsation musicale avec le Montreal – Beat Alignment Test (M-BAT)

Bellemare Pepin, Antoine 01 1900 (has links)
Il existe actuellement de nombreux tests visant à mesurer la capacité à percevoir la pulsation rythmique dans la musique ainsi que l’habileté à synchroniser ses mouvements avec celle-ci. Ces tests présentent toutefois certaines lacunes méthodologiques (longue durée d’administration, différence de stimuli entre les sous-tests, mauvais appariement des conditions). Le Montreal-Beat Alignment Test (M-BAT) a été élaboré afin de palier à ces lacunes et d’offrir une mesure simple et sensible de ces habiletés. Une étude de sensibilité a été menée auprès de 90 participants. Pour la tâche de perception, nous observons une distribution avec une légère asymétrie négative et sans présence d’effet plancher ou plafond. Les performances aux tâches de perception et de synchronisation sont modérément corrélées, suggérant qu’une bonne perception de la pulsation s’accompagne généralement d’une bonne capacité à se synchroniser avec celle-ci. Également, des cas de déficits dans l’une et/ou l’autre de ces habiletés sont rapportés, indiquant la présence de dissociations entre perception et synchronisation à la pulsation musicale. / There are currently many tests to measure the abilities to perceive the beat in music and to synchronize its movements with it. These tests, however, have certain methodological shortcomings (long duration of administration, different stimuli between sub-tests, mismatch conditions). The Montreal-Beat Alignment Test (M-BAT) has been developed to overcome these deficiencies and provide a simple and sensitive measurement of these skills. A sensitivity study was conducted with 90 participants. For the task of perception, we see a distribution with a slight negative asymmetry and without the presence of floor or ceiling effect. The performances for the perception and synchronization tasks are moderately correlated, suggesting that a good perception of the pulse is usually accompanied by a good ability to synchronize with it. Also, case deficits in one and/or the other of these skills are reported, indicating the presence of dissociations between perception and synchronization with the musical beat.
46

Optimization and simulation of formed suction cup to position aerospace CFRP parts during milling.

Sivasubramanian, Sriramkumar January 2019 (has links)
FLEXOMAT
47

An Analysis of The Effect of 3-D Groove Insert Design on Chip Breaking Chart

Avanessian, Alfred 25 January 2005 (has links)
Abstract Prediction of chip-breaking in machining is an important task for automated manufacturing. There are chip-breaking limits in machining chip-breaking chart, which determine the chip-breaking range. This thesis presents a study of the effect of 3-D groove insert parameters on chip breaking chart. Based on the chip-breaking criteria, the critical feed rate is formulated through an analysis of up-curl chip formation for 3-D grooves. Also in order to predict chip-breaking limits, for protruded insert grooves in finish machining, analytical models are established. In the analytical models, minimum and maximum depth of cut are identified for using different chip breaking models. As well insert nose radius effects on chip thickness for small depth of cut are studied. In the end, the analytical critical feed rate model is extended to finish machining with 3-D chipbreaking grooves.
48

Freqüência do sulco palatogengival e morfologia dos canais de dentes portadores antes e depois do preparo biomecânico / Frequency of the palatogengival groove and morphologic analysis of the root canals of affected teeth before and after root canal preparation

Tiago Novaes Pinheiro 13 February 2006 (has links)
O sulco palatogengival representa uma anomalia com morfologia propícia ao acúmulo de microorganismos e possibilidade de comunicação com a cavidade pulpar, podendo acarretar em doença periodontal localizada, cárie dentária, pulpopatias e periapicopatias. Investigou-se a etiopatogenia, seus meios de diagnóstico para colaborar na determinação de prognósticos precisos baseados na detecção das dificuldades do manejo dessas situações clínicas decorrentes. Detectou-se sua freqüência em 500 pacientes, correlacionando sua presença com características pessoais e sua ocorrência na família de indivíduos portadores. Também foram utilizados 20 incisivos permanentes superiores portadores do sulco palatogengival avaliando macro e microscopicamente a morfologia dos canais radiculares antes e depois do preparo biomecânico, bem como a relação do compartimento pulpar com o meio externo. Os espécimes foram observados macroscopicamente, com o auxílio do estereomicroscópio, radiografados e analisados à microscopia eletrônica de varredura antes e depois do preparo biomecânico utilizando a técnica de mufla modificada de BRAMANTE et al.. A prevalência do sulco palatogengival na amostra de 500 pacientes avaliados, foi de 19,8%, sendo que o dente mais afetado foi o incisivo lateral superior com 80,4% de prevalência, ocorrendo tanto unilateralmente quanto bilateralmente. Observou-se a prevalência de 8,4% de doenças relacionadas ao sulco. Não se detectou diferenças entre gêneros e cor de pele, quanto à presença do defeito. Não foi observada nenhuma correlação entre a presença do sulco palatogengival e as características físicas avaliadas. Identificou-se a presença do sulco palatogengival em pessoas de uma mesma família. A análise de 20 incisivos superiores com sulco palatogengival permitiu a identificação de forames, foraminas e túbulos dentinários no leito do sulco palatogengival, comunicando o compartimento pulpar com o periodontal. Identificaram-se alterações no contorno e variações do tipo de junção amelocementária. O desgaste produzido pela instrumentação dos canais nos dentes da amostra foi uniforme, não havendo diferenças significantes entre as paredes instrumentadas nem nos fragmentos cervical, médio e apical dos canais. A parede dentinária atingida pelo sulco palatogengival foi a mais fina antes e depois do preparo biomecânico. / The palatogengival groove represents an anomaly with favorable morphology to the accumulation of microorganisms and possible communication with the pulp chamber, leading to localized periodontal disease, dental caries, pulp and periapical diseases. It was aimed to investigate the origin, the diagnostic means and to collaborate for determination of prognostic measures based on the detection of difficulties with handling of the current clinical situations related to the groove. The frequency in 500 patients was evaluated, correlating the presence of the groove with individual characteristics end its presence in the family of the bearers. Also 20 permanent previously extracted upper incisors with the palatogengival groove were evaluated as to the root canal morphology macro and microscopically, before and after root canal preparation. The relationship of the pulp chamber with the external environment, in these specimens was evaluated. The specimens were observed macroscopically, by means of stereomicroscope, x-ray and analyzed through scanning electronic microscopy before and after root canal preparation using a modified muffle technique from BRAMANTE et al.. The prevalence of the palatogengival groove in 500 patients, was of 19,8%, and the most affected tooth was the upper lateral incisor with 80,4% of prevalence, with unilateral and bilateral manifestation. It was detected the prevalence of 7,8% of groove related diseases. It was not detected differences between gender and skin color, with the presence of the defect. No correlations were observed between the presence of the palatogengival groove and the studied physical characteristics. It was identified the presence of the palatogengival groove in patients of the same family. The analysis of 20 upper incisors with palatogengival groove allowed the identification foramen, foraminas and exposed dentinal tubules in the radicular surface of the groove, communicating the pulp chamber with the periodontal compartment. Alterations in the outline and variations of the type of the cement enamel junction were also detected. The dentin removal produced by root canal instrumentation of the studied teeth was uniform, with no significant differences among the different dentinal walls or in the cervical, medium and apical fragments of the analyzed teeth. The dentinal wall related to the palatogengival groove was thinner before and after the root canal preparation compared with the remaining dentinal walls.
49

Freqüência do sulco palatogengival e morfologia dos canais de dentes portadores antes e depois do preparo biomecânico / Frequency of the palatogengival groove and morphologic analysis of the root canals of affected teeth before and after root canal preparation

Pinheiro, Tiago Novaes 13 February 2006 (has links)
O sulco palatogengival representa uma anomalia com morfologia propícia ao acúmulo de microorganismos e possibilidade de comunicação com a cavidade pulpar, podendo acarretar em doença periodontal localizada, cárie dentária, pulpopatias e periapicopatias. Investigou-se a etiopatogenia, seus meios de diagnóstico para colaborar na determinação de prognósticos precisos baseados na detecção das dificuldades do manejo dessas situações clínicas decorrentes. Detectou-se sua freqüência em 500 pacientes, correlacionando sua presença com características pessoais e sua ocorrência na família de indivíduos portadores. Também foram utilizados 20 incisivos permanentes superiores portadores do sulco palatogengival avaliando macro e microscopicamente a morfologia dos canais radiculares antes e depois do preparo biomecânico, bem como a relação do compartimento pulpar com o meio externo. Os espécimes foram observados macroscopicamente, com o auxílio do estereomicroscópio, radiografados e analisados à microscopia eletrônica de varredura antes e depois do preparo biomecânico utilizando a técnica de mufla modificada de BRAMANTE et al.. A prevalência do sulco palatogengival na amostra de 500 pacientes avaliados, foi de 19,8%, sendo que o dente mais afetado foi o incisivo lateral superior com 80,4% de prevalência, ocorrendo tanto unilateralmente quanto bilateralmente. Observou-se a prevalência de 8,4% de doenças relacionadas ao sulco. Não se detectou diferenças entre gêneros e cor de pele, quanto à presença do defeito. Não foi observada nenhuma correlação entre a presença do sulco palatogengival e as características físicas avaliadas. Identificou-se a presença do sulco palatogengival em pessoas de uma mesma família. A análise de 20 incisivos superiores com sulco palatogengival permitiu a identificação de forames, foraminas e túbulos dentinários no leito do sulco palatogengival, comunicando o compartimento pulpar com o periodontal. Identificaram-se alterações no contorno e variações do tipo de junção amelocementária. O desgaste produzido pela instrumentação dos canais nos dentes da amostra foi uniforme, não havendo diferenças significantes entre as paredes instrumentadas nem nos fragmentos cervical, médio e apical dos canais. A parede dentinária atingida pelo sulco palatogengival foi a mais fina antes e depois do preparo biomecânico. / The palatogengival groove represents an anomaly with favorable morphology to the accumulation of microorganisms and possible communication with the pulp chamber, leading to localized periodontal disease, dental caries, pulp and periapical diseases. It was aimed to investigate the origin, the diagnostic means and to collaborate for determination of prognostic measures based on the detection of difficulties with handling of the current clinical situations related to the groove. The frequency in 500 patients was evaluated, correlating the presence of the groove with individual characteristics end its presence in the family of the bearers. Also 20 permanent previously extracted upper incisors with the palatogengival groove were evaluated as to the root canal morphology macro and microscopically, before and after root canal preparation. The relationship of the pulp chamber with the external environment, in these specimens was evaluated. The specimens were observed macroscopically, by means of stereomicroscope, x-ray and analyzed through scanning electronic microscopy before and after root canal preparation using a modified muffle technique from BRAMANTE et al.. The prevalence of the palatogengival groove in 500 patients, was of 19,8%, and the most affected tooth was the upper lateral incisor with 80,4% of prevalence, with unilateral and bilateral manifestation. It was detected the prevalence of 7,8% of groove related diseases. It was not detected differences between gender and skin color, with the presence of the defect. No correlations were observed between the presence of the palatogengival groove and the studied physical characteristics. It was identified the presence of the palatogengival groove in patients of the same family. The analysis of 20 upper incisors with palatogengival groove allowed the identification foramen, foraminas and exposed dentinal tubules in the radicular surface of the groove, communicating the pulp chamber with the periodontal compartment. Alterations in the outline and variations of the type of the cement enamel junction were also detected. The dentin removal produced by root canal instrumentation of the studied teeth was uniform, with no significant differences among the different dentinal walls or in the cervical, medium and apical fragments of the analyzed teeth. The dentinal wall related to the palatogengival groove was thinner before and after the root canal preparation compared with the remaining dentinal walls.
50

Structural Factors that Influence the Inhibition of Type II Restriction Enzymes by Minor Groove Binders

Nguyen, Ha Hoang 13 April 2009 (has links)
The objective of this thesis was to study whether heterocyclic dicationic compounds that are minor groove binders have the ability to inhibit the digestive properties of type II restriction enzymes which bind to the major groove of the DNA. If these compounds do possess the ability to inhibit restriction enzymes, then what factors influence their ability to inhibit the restriction enzymes? The methods used to study the interactions of DNA, compounds, and enzymes are gel electrophoresis, DNA thermal melting, and circular dichroism. The results from this project reveal that the minor grove binding compounds are able to inhibition type II restriction enzymes. The inhibition is heavily influenced by compound structure and the DNA binding sequence of the enzyme.

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