Academic literature on the topic 'Potts glass'
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Journal articles on the topic "Potts glass"
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Yokota, Terufumi. "Glass–Glass Transition in a Potts Model." Journal of the Physical Society of Japan 80, no. 1 (January 15, 2011): 014708. http://dx.doi.org/10.1143/jpsj.80.014708.
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Krząkała, F., and L. Zdeborová. "Potts glass on random graphs." EPL (Europhysics Letters) 81, no. 5 (February 4, 2008): 57005. http://dx.doi.org/10.1209/0295-5075/81/57005.
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BENGTSSON, MATS, and PERTTI ROIVAINEN. "USING THE POTTS GLASS FOR SOLVING THE CLUSTERING PROBLEM." International Journal of Neural Systems 06, no. 02 (June 1995): 119–32. http://dx.doi.org/10.1142/s012906579500010x.
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We present an application of a Potts glass to the clustering problem. Simulated annealing in the mean field approximation is used in order to avoid local minima. The resulting updating equations are completely parallel, and very easy to implement. The model has no free parameters except for the annealing parameters. We show how the model can be implemented for some special clustering problems. The T→0 limit of the Potts glass is identical to the vector quantization algorithm with certain increments. A comparative study of the Potts glass and vector quantization is also made, and it is shown that for difficult clustering problems, the Potts glass is far better than vector quantization.
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Kanter, Ido. "Potts-glass models of neural networks." Physical Review A 37, no. 7 (April 1, 1988): 2739–42. http://dx.doi.org/10.1103/physreva.37.2739.
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Cherepanov, V. B., S. L. M. Cyr, and B. W. Southern. "Metastable states of the Potts glass." Journal of Physics A: Mathematical and General 25, no. 16 (August 21, 1992): 4347–58. http://dx.doi.org/10.1088/0305-4470/25/16/012.
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de Oliveira, Mário J., and Sílvio R. Salinas. "Potts glass on the Bethe lattice." Physical Review B 35, no. 16 (June 1, 1987): 8744–46. http://dx.doi.org/10.1103/physrevb.35.8744.
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Bolle, D., and F. Mallezie. "Image evolution in Potts-glass neural networks." Journal of Physics A: Mathematical and General 22, no. 20 (October 21, 1989): 4409–18. http://dx.doi.org/10.1088/0305-4470/22/20/017.
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Gross, D. J., I. Kanter, and H. Sompolinsky. "Mean-field theory of the Potts glass." Physical Review Letters 55, no. 3 (July 15, 1985): 304–7. http://dx.doi.org/10.1103/physrevlett.55.304.
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Chang, Mau-chung. "Two-loop renormalization of Potts spin-glass." Physical Review B 31, no. 7 (April 1, 1985): 4329–36. http://dx.doi.org/10.1103/physrevb.31.4329.
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Panchenko, Dmitry. "Free energy in the Potts spin glass." Annals of Probability 46, no. 2 (March 2018): 829–64. http://dx.doi.org/10.1214/17-aop1193.
Full textDissertations / Theses on the topic "Potts glass"
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Martinez, Alexandre Souto. "Estudo da função de correlação do modelo de Potts na rede de Bethe." Universidade de São Paulo, 1988. http://www.teses.usp.br/teses/disponiveis/54/54131/tde-22052009-090142/.
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Neste trabalho consideramos o modelo de Potts na árvore de Cayley submetida a um campo magnético. Esse campo pode ser representado pela interação dos spins da árvore com um spin adicional, denominado spin fantasma. Essa nova rede passa a ser chamada de árvore de Cayley fechada e assimétrica. Sendo uma rede hierárquica, ela representa soluções exatas que são obtidas quando as técnicas do grupo de renormalização no espaço real são aplicadas. Subtraindo os efeitos de superfície e considerando somente o interior da árvore (rede de Bethe), esses resultados reproduzem os resultados da aproximação de campo médio de Bethe-Peierls. Com a finalidade de estudar a função de correlação do modelo de Potts na rede de Bethe, consideramos primeiramente uma cadeia de Potts interagindo com um spin fantasma. Através das regras de composição em série e paralelo e do método da quebra e colapso para as trasmissividades térmicas (função de correlação) obtemos uma fórmula de recorrência para a função de correlação entre quaisquer dois spins na cadeia. Mostramos então que pela invariança translacional da rede de Bethe qualquer par de spins pode ser mapeado no sistema anterior. A seguir consideramos o modelo de Potts de um estado na árvore de Cayley fechada e assimétrica. Decimando os spins interiores da unidade geradora da rede, obtemos um mapa polinomial quadrático para a transformação do grupo de renormalização (mapa de Bethe-Peierls). O diagrama de fase desse sistema é então obtido do conjunto de Mandelbrot através de uma transformação de Mobius. O mapa de Bethe-Peierls apresenta dois pontos fixos, que são relacionados com as fases ferro e paramagnética e o regime caótico é identificado com a fase vidro de spin. Esse sistema revela ser o exemplo mais simples de vidro de spin de McKay-Berker-Kirkpatrick. Na rede de Bethe e a campo nulo esse sistema apresenta transições de fase de segunda ordem. Analisando o comportamento crítico da função de correlação e de suas derivadas, vemos que se identificarmos a função de correlação entre o spin fantasma e qualquer spin da rede com a magnetização (por spin) e a função de correlação entre dois spins primeiros vizinhos com a energia interna do sistema, cinco expoentes críticos ((δ, β, γ ’, α, α ’) são calculados e satisfazem as relações de escala. Para ilustrar o procedimento recursivo apresentado para calcular a função de correlação entre dois spins separados por ligações m na rede de Bethe, consideramos os spins de Potts de um estado. Obtemos então de forma explícita as correlações para m=1, 2 e 3.0In this work we consider the Potts model on the Cayley tree subjected to a magnetic Field. This field can be represented by the interaction of the tree spins with an additional one, denominated ghost spin. This new lattice is then called closed-asymmetric Cayley tree. Being a hierarchical lattice it comes to have exact solutions which are obtained when the real-space renormalization group techniques are applied. Subtracting the surface effects and considering only the tree interior (Bethe lattice), these results reproduce the results of Bethe-Peierls mean-field approximation. With the objective of studying the pair-correlation function of the Potts model on the Bethe lattice, we at first consider a Potts chain interacting with a ghost spin. Throughout the series-parallel composition rules and the break-collapse method for the thermal transmissivities (pair-correlation function) we obtain a recursive relation for the correlation function between any two spins on the chain. We then show, due to the translational invariance of the Bethe lattice, that any pair of spins can be mapped into the latter system. Next we consider the one-state Potts model on the closed asymmetric tree. Decimating the inner spins of the generating unit for the lattice, we obtain a quadratic polynomial map for the renormalization group transformation (Bethe-Peierls map). The phase diagram of this system is obtained from the Mandelbrot set throughout a Mobius transformation. The Bethe-Peierls map has two stable fixed points which are related to the ferro and paramagnetic phases and the chaotic regime is identified with the spin-glass phase. This system turns out to be the simplest example of a McKay-Berker-Kirkpatrick spin glass. On the Bethe lattice with vanishing field this system presents second-order phase transitions. Analyzing the critical behavior of the pair-correlation function and of this derivatives, we see that if we identify the correlation function between the ghost spin and any spin on the lattice with the magnetization (per spin), and the correlation function between two nearest-neighbor spins with the internal energy of the system, five critical exponents (δ, β, γ ’, α, α ’) are calculated and they satisfy the scaling relations. In order to illustrate the recursive procedure presented to calculate the pair-correlation function between spins m bonds apart on the Bethe lattice, we consider the one-state Potts spins. We obtain explicitly the correlation for m=1, 2 and 3.
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Cardenas, José Edgar Valdivia. "Avaliação da espessura de cimento e resistência adesiva de pinos de fibra de vidro cônicos em preparo para retentor intra-radicular realizados com uma ponta ultrassônica desenvolvida." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/23/23156/tde-24012018-114059/.
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Preparos para retentores intra-radiculares mais conservadores evitam desgaste desnecessário da estrutura dentinária, requer menos cimento e podem melhorar a retenção adesiva do pino. Assim o objetivo deste estudo foi avaliar a espessura de cimento ea resistência adesiva de pinos de fibra de vidro cônicos em preparo para retentor intra-radicular realizados com uma ponta ultrassônica desenvolvida. Trinta incisivos laterais superiores foram preparados com limas reciprocantes Wave One Gold (Dentsply Sirona, Ballaigues, Suiça) e aleatoriamente divididos em 2 grupos (n=15) de acordo com a técnica de preparo para pino: grupo US foram preparados com uma ponta ultrassônica desenvolvida, e grupo WP (controle) com a broca recomendada pelo fabricante do pino. Os pinos de fibra de vidro cônicos WhitePost DC 0.5 (FGM, Joinville, SC, Brasil) foram cimentados utilizando cimento resinoso dual nos terços cervical e médio do canal radicular. Isto posto, todos os espécimes foram seccionados transversalmente em três seções (cervical, média e apical do pino) para análise da área de cimento resinoso ao redor do pino que foi calculada através do programa AutoCAD, em seguida, para avaliar a resistência adesiva, o teste de cisalhamento por extrusão foi aplicado através de uma maquina de ensaio universal numa velocidade média de 0.5 mm/min até o deslocamento do conjunto restaurador intra-radicular e o tipo de falha avaliado por estereomicroscopia. A comparação entre grupos e entre terços da área de cimento e resistência adesiva foram analisadas pelo teste t independente e Anova com Tukey; e os tipos de falha entre os grupos por Mann-Whitney, todos com nível de significância de 5%. No grupo ultrassônico foi observado a menor quantidade de cimento (p<0.05) e a resistência adesiva nos diferentes grupos e terços se manifestou maior somente no terço apical do grupo ultrassônico (p<0.05). Falha adesiva entre cimento e dentina foi a mais prevalente do terço cervical e apical do grupo US e cervical de grupo WP. Falha adesiva entre cimento e pino foi a mais prevalente nos demais terços. Conclui-se que o preparo para retentor com a ponta ultrassônica desenvolvida requer menor quantidade de cimento e influencia na melhor resistência de união no terço apical do pino de fibra de vidro.Conservative post space preparations for intra-radicular retainers prevent unnecessary desgaste of the dentin structure, require less cement and improve bond strength of the post. The aim of this study was to evaluate the influence of resin cement thickness and bond strength of prefabricated glass fiber circular postin post space preparations with an ultrasonic tip developed. Thirtymaxillarylateral incisors were prepared with Wave One Gold reciprocating files (Dentsply Sirona, Ballaigues, Switzerland) and randomly divided into 2 groups (n=15) according to the post preparation technique: gruoup US was prepared with an ultrasonic tip developed and group WP (control) with the drill recommended by the post fabricant. Every glass fiber posts WhitePost DC 0.5 (FGM, Joinville, SC, Brazil) was cemented using dual polymerizing resin cement in the cervical and middle thirdof the root canal. After that, every specimen was sectioned transversally into three sections(cervical, middle and apical of the post) and the resin cement thickness area was calculated with AutoCAD program, the bond strength test was done with an universal testing machineat medium velocity 0.5 mm/min and the failure pattern after the test was analyzed with stereomicroscopy. Datas obtained were analyzed statistically using Student\'s t-Test, ANOVA,andTukey\'s test. The comparison of failure modes between the groups in the different thirds was done using Mann-Whitney test, All of those at a 5% significance. Ultrasonic group presented thinnest layer of cement in all thirds (p<0,05), which also obtained a higher bond strength only in apical third (p<0,05). Adhesive failurebetween cement and dentinwas the most prevalent of the cervical and apical third of G1 and cervical of G2.Adhesive failure between cement and post was the most prevalent in the others thirds. It can be concluded that the postpreparation with the ultrasonic tip developed provides a smaller thickness of resin cement that influenced thebond strength in the apical third of the glass fiber post.
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Neto, Aminthas Alves Brasil. "AvaliaÃÃo da resistÃncia de uniÃo da interface adesiva de pinos de fibra de vidro e a dentina radicular." Universidade Federal do CearÃ, 2007. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=668.
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nÃo hÃO objetivo deste trabalho foi avaliar a resistÃncia de uniÃo da interface adesiva de pinos de fibra de vidro e dentina radicular, em trÃs regiÃes do conduto, fixados com trÃs sistemas de cimentaÃÃo. Vinte e quatro dentes humanos hÃgidos, recÃm-extraÃdos por razÃes ortodÃnticas ou periodontais, tiveram suas coroas removidas na junÃÃo cemento-esmalte com um disco diamantado, sob irrigaÃÃo. As raÃzes receberam tratamento endodÃntico e foram obturadas com guta-percha e um cimento endodÃntico contendo eugenol (Endofil). A desobstruÃÃo foi realizada uma semana apÃs o tÃrmino do tratamento endodÃntico em uma profundidade de 9 mm medida da regiÃo cervical da raiz. O pino (Reforpost Fibra de Vidro n 3) foi cimentado no conduto radicular com um dos trÃs sistemas de fixaÃÃo descritos a seguir (n = 8): no grupo 1 foi utilizado o sistema Single Bond 2/ RelyX ARC, no grupo 2 foi utilizado o sistema ED Primer/Panavia 21 e no grupo 3 foi utilizado o cimento RelyX Unicem. Todos os cimentos e sistemas adesivos foram utilizados de acordo com as instruÃÃes dos fabricantes. Posteriormente, as raÃzes foram seccionadas em uma mÃquina de corte, sob irrigaÃÃo, em trÃs porÃÃes, correspondentes aos terÃos cervical, mÃdio e apical da regiÃo do conduto preparada para o pino. Os espÃcimes foram submetidos ao teste de extrusÃo por cisalhamento (âpush-outâ) em uma mÃquina de ensaio universal a uma velocidade de 0,5 mm/min e os valores de resistÃncia de uniÃo mÃxima foram registrados e submetidos à anÃlise estatÃstica (p < 0,05). A anÃlise de variÃncia (ANOVA) mostrou diferenÃa estatÃstica significante entre os terÃos (cervical, mÃdio e apical) somente para o grupo do cimento Panavia 21, no qual o terÃo apical apresentou menor mÃdia de resistÃncia de uniÃo do que os terÃos cervical e mÃdio (teste de Tukey). Quando se comparou a resistÃncia de uniÃo em cada regiÃo da raiz, avaliando-se os materiais de cimentaÃÃo, a anÃlise de variÃncia (ANOVA) mostrou diferenÃa estatÃstica significante para as trÃs regiÃes do conduto. Para os terÃos mÃdio e apical, o cimento Panavia 21 apresentou mÃdia de resistÃncia de uniÃo significativamente menor do que os cimentos Single Bond 2/RelyX ARC e RelyX Unicem, sendo estes estatisticamente iguais entre si. Para o terÃo cervical, o cimento RelyX Unicem apresentou maiores valores de resistÃncia de uniÃo do que o cimento Panavia 21, tendo sido o cimento Single Bond 2/RelyX ARC estatisticamente semelhante aos outros dois materiais
The aim of this study was to assess the bond strength at the adhesive interface of fiber glass posts and root dentin, in three regions of the canal, fixed with three cementation systems. Twenty-four healthy human teeth, recently extracted for orthodontic or periodontal reasons, had their crowns removed at the cement-enamel junction with a diamond disk, under irrigation. The roots were endodontically treated and were filled with gutta percha and an endodontic cement containing eugenol (Endofil). One week after endodontic treatment ended, the obstruction was removed at a mean depth of 9mm in the cervical region of the root. The posts (Reforpost Fibra de Vidro No. 3) were cemented in the canals prepared with one of the three fixation systems described as follows (n = 8): in group 1 the Single Bond 2/ RelyX ARC system was used; in group 2 the ED Primer/Panavia 21 system, and in group 3 RelyX Unicem cement was used. All the cements and adhesive systems were used in accordance with the manufacturersâ instructions. Afterwards, the roots were sectioned in a cutting machine under irrigation, into three portions corresponding to the cervical, middle and apical thirds of the root canal region prepared for the post. The specimens were submitted to the pushout test in a universal test machine at a speed of 0.5 mm/min and the maximum bond strength values were recorded and submitted to statistical analysis (p < 0.05). Analysis of variance (ANOVA) showed statistically significant difference between the cervical, middle and apical thirds only for the Panavia 21 cement group, in which the apical third presented a lower mean bond strength value than the cervical and middle thirds (the TukeyÂs test). When the bond strength in each region of the root was compared to assess the cementing materials, the analysis of variance (ANOVA) showed statistically significant different for the three regions of the canal. For the middle and apical thirds, the Panavia 21 cement presented significantly lower mean bond strength than the Single Bond 2/RelyX ARC and RelyX Unicem cements, these being statistically equal between them. For the cervical third, RelyX Unicem cement presented higher bond strength values than the Panavia 21 cement and the Single Bond 2/RelyX ARC cement was statistically equal to the other two materials
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Barreto, Mirela Sangoi. "EFEITO DE SOLUÇÕES ATIVADAS POR ULTRASSOM NA RESISTÊNCIA ADESIVA DE PINOS DE FIBRA DE VIDRO CIMENTADOS COM CIMENTO RESINOSO AUTOADESIVO." Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/6160.
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The current study aimed to evaluate the effect of irrigating and chelating solutions on bond
strength of fiber glass posts cemented with RelyX U200. 60 single-rooted premolars were
sectioned at 14 mm from the apex, prepared with ProTaper Universal system until F3
instrument and filled with F3 master cone and AH Plus sealer. Root canal filling was partially
removed, remaining 4 mm of guta-percha at the apical third. Specimens were randomly
divided into 5 experimental groups (n=12), according to the solution used before fiber post
cementation (dentin surface treatment), as described: EDTA 17% (EDTA); QMix (QM);
SmearClear (SC); NaOCl 2.5% (NaOCl) and saline solution as control group (SS). Ultrasonic
activation was performed three times, during 20 seconds each and root canals were dried with
paper points. Exacto N2 glass fiber posts were cemented with RelyX U200. Rhodamine B dye
was mixed to RelyX U200 in one specimen per group, in order to provide fluorescence for
confocal laser scanning microscopy (CLSM) assessment. A cutting machine was used for
root s sectioning, providing 3 slices, one for each root third. Next, push-out test was
performed. Stereomicroscope and CLSM were used to analyze the failure mode and to
illustrate the pattern of distribution of RelyX U200 inside dentinal tubules, respectively. Bond
strength mean were calculated and ANOVA and Bonferroni tests were used for statistical
analysis. SS showed the higher mean of bond strength values, superior to QM, SC (P < .05).
NaOCl presented intermediary bond strength values, similar to EDTA and SS (P > .05). QM
and SC showed the lowest mean of bond strength (P < .05). In conclusion, SS and NaOCl
associated to ultrasonic activation seems to be adequate solutions for root canal cleaning
before fiber post cementation with RelyX U200, while chelating solutions, such as EDTA,
QMix and SmearClear, should not be used for dentin pre-treatment when cementing with
RelyX U200.O presente estudo tem por objetivo avaliar o efeito de diferentes soluções irrigantes e quelantes na resistência adesiva de pinos de fibra de vidro cimentados com cimento autoadesivo RelyX U200. 60 pré-molares inferiores extraídos de humanos, padronizados em 14 mm, foram preparados com o sistema ProTaper Universal até o instrumento F3, obturados com cimento AH Plus e cones F3 do mesmo sistema. Os espécimes foram desobturados parcialmente, restando 4 mm apicais de material obturador e realocados em quatro grupos experimentais e um controle (n=12), de acordo com a solução de tratamento de superfície dentinária prévia à cimentação dos pinos: EDTA 17% (EDTA), QMix (QM), SmearClear (SC), Soro Fisiológico (SS) e NaOCl 2,5% (NaOCl). As soluções foram ativadas por ultrassom em três etapas, durante 20 segundos cada e os canais foram secos com pontas de papel absorventes. Os pinos de fibra de vidro do Sistema Exacto Translúcido N2 foram cimentados com RelyX U200. Em um espécime por grupo foi incorporada Rodamina B ao cimento autoadesivo como marcador fluorescente para análise em Microscopia Confocal à laser (MECL). Foram seccionados 3slices por espécime, sendo 1 slice por terço radicular, e submetidos ao teste de push-out na máquina de ensaio universal EMIC. Estereomicroscópio e MECL foram utilizados para analisar o padrão de falha dos espécimes e o padrão de penetração do cimento autoadesivo nos túbulos dentinários, respectivamente. A média de resistência adesiva de cada espécime foi calculada. Testes ANOVA e Bonferroni foram utilizados para analisar as diferenças entre os grupos. SS demonstrou a maior média de resistência adesiva, sendo superior aos grupos QM, SC (P <.05). NaOCl apresentou valores intermediários de resistência adesiva, similares ao EDTA e SS (P > .05). QM e SC apresentaram as menores médias de resistência adesiva (P < .05). Pode-se concluir que o uso de SS e NaOCl parece ser adequado para lavagem do canal prévia à cimentação de pinos de fibra de vidro, com uso de cimento resinoso autoadesivo RelyX U200. O uso de soluções quelantes como EDTA, QM e SC parece interferir negativamente nos valores de resistência adesiva.
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Yamin, Paulo André. "Resistência de união de cimentos resinosos à dentina previamente submetida a radioterapia." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/58/58133/tde-01032018-170046/.
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Este estudo avaliou, in vitro, a influência da radioterapia na resistência de união (RU) e na interface adesiva entre diferentes cimentos resinosos e dentina radicular. Sessenta caninos superiores foram distribuídos em 2 grupos (n=30) de acordo com a irradiação: não irradiados e irradiados. Os dentes do grupo irradiado foram submetidos à radioterapia com raios-X de 6 MV em frações de 2 Gy, com 30 ciclos, perfazendo 60 Gy. Os dentes foram seccionados para obtenção de raízes com 16 mm de comprimento, sendo realizado em seguida o preparo biomecânico com instrumento Reciproc R50 e obturação pela técnica de condensação lateral com cimento a base resina epóxica. Cada grupo foi subdividido de acordo com o cimento resinoso utilizado para a cimentação dos pinos de fibra de vidro (n=10): RelyX U200; Panavia F 2.0; RelyX ARC. Os pinos foram submetidos a tratamento de superfície com ácido fluorídrico 10% e cimentados de acordo com as recomendações de cada fabricante. Após a cimentação dos pinos, os dentes foram seccionados transversalmente em slices de 1 mm de espessura, obtendo-se 3 slices de cada terço da raiz. Os slices mais cervicais de cada terço foram utilizados para avaliar a RU, por meio do teste de push-out com velocidade de 0,5 mm/min, e posterior análise do padrão de falha em estereomicroscópio. Os slices mais apicais de cada terço foram selecionados para análise da interface cimento/dentina em MEV com aumentos de 100, 1000, 2000 e 4000X. Os dados de RU e adaptação da interface cimento/dentina foram submetidos à análise estatística pelos testes de ANOVA e Tukey, e Kruskal-Wallis e Duns, respectivamente. Os espécimes irradiados apresentaram menores valores de RU (8,23±4,26) comparados aos dentes não irradiados (11,88±6,42) (p<0,00001). Quanto aos cimentos resinosos, o RelyX U200 apresentou maiores valores na RU (15,17±5,89) comparado aos cimentos RelyX ARC (7,68±4,22) (p<0,0001) e Panavia F 2.0 (7,32±2,71) (p<0,0001). O terço cervical apresentou maiores valores de RU (13,08±6,10) comparado aos terços médio (9,72±5,03) e apical (7,38±4,53) (p<0,0001). O padrão de falhas mostrou ocorrência de falhas coesivas na dentina para os espécimes irradiados. Na análise da interface cimendo/dentina por MEV, observou-se maior desadaptação nos dentes submetidos à radioterapia. Em relação aos cimentos resinosos, foi observada maior adaptação com RelyX U200 e RelyX ARC comparados à Panavia F 2.0. Na análise qualitativa em MEV observou-se presença de fraturas e microfraturas na dentina radicular e menor presença de fibras colágenas em dentes irradiados. Para o cimento resinoso RelyX U200 e Panavia F 2.0 observou-se interface justaposta do cimento com a dentina radicular em dentes irradiados e não irradiados, sendo que para o cimento resinoso RelyX ARC foi observada formação de camada híbrida e tags de maneira similar para dentes irradiados e não irradiados. Concluiu-se que a radioterapia resultou na redução da resistência de união e na maior desadaptação da interface cimento resinoso/dentina radicular e que o cimento resinoso autoadesivo se apresentou como melhor alternativa para cimentação de pinos de fibra de vidro em dentes irradiados.This in vitro study, evaluated the influency of radiotherapy on bond strength (BS) and adhesive interface between different resin cements and root dentin. Sixty maxillary canines were selected and distributed into two groups (n = 30) according to the irradiation protocol: non-irradiated and irradiated. The irradiated group were submitted to X-ray radiotherapy of 6 MV in fractions of 2 Gy, with 30 cycles, until complete 60 Gy. The teeth were sectioned to obtain 16 mm of root length, followed by biomechanical preparation with R50 reciproc instrument and obturation using the lateral condensation technique with epoxy resin-based sealer. Then, each group was subdivided according to the resin cement used for the glass fiber post cementation (n = 10): RelyX U200, Panavia F 2.0 and RelyX ARC. The posts were submitted to surface treatment with 10% hydrofluoric acid, and then cemented according to the manufacturer instructions. After the posts cementation, the teeth were sectioned transversely into 1 mm thick slices, and 3 slices were obtained from each root third. The most cervical slice of each third was used to evaluate the BS by the push-out test at 0.5 mm/min of velocity and the failure pattern was analyzed using stereomicroscopy. The most apical slice of each third was selected for SEM analysis, which were prepared and metalized. The dentin/cement interface analysis was performed at the following magnification: 100, 1000, 2000 and 4000X. The BS data and dentin/cement interface adaptation were submitted to statistical analysis by ANOVA, Tukey and Kruskal-Wallis, and Duns tests respectively. The irradiated specimens had lower BS values (8.23 ± 4.26) compared to non-irradiated group (11.88 ± 6.42) (p <0.00001). Regarding the resin cements, the RelyX U200 showed the higher values in BS (15.17 ± 5.89) compared to RelyX ARC (7.68 ± 4.22) and Panavia F 2.0 (7 , 32 ± 2.71) (p <0.0001). In addition, the cervical third presented higher BS values (13.08 ± 6.10) when compared to the middle (9.72 ± 5.03) and apical (7.38 ± 4.53) thirds (p <0.0001). The failure pattern showed cohesive failures in root dentin of the irradiated specimens. In the SEM dentin/cement interface analysis, a greater misadaptation was observed for the teeth submitted to radiotherapy. Regarding the resin cements, a better adaptation was observed for the RelyX U200 and RelyX ARC compared to the Panavia F 2.0. In the SEM qualitative analysis of the irradiated teeth, was possible to observe the presence of fractures and microfractures in the root dentin and a small number of collagen fibers. The resin cements RelyX U200 and Panavia F 2.0 showed a juxtaposed interface of the cement with the root dentin in irradiated and non-irradiated teeth, being that for the RelyX ARC cement the presence of hybrid layer and tags was similar for irradiated and non-irradiated groups. It was concluded that the radiotherapy promoted reduction of the bond strength and increase the gaps in the dentin/resin cement interface and the self-adhesive resin cement is the best alternative for glass fiber posts cementation in irradiated teeth.
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Seballos, Vívian Gehm. "EFEITO DE DIFERENTES SOLUÇÕES IRRIGADORAS SOBRE A RESISTÊNCIA ADESIVA DE PINOS DE FIBRA DE VIDRO COM UTILIZAÇÃO DE CIMENTO AUTOADESIVO." Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/6186.
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The purpose of this study is to evaluate the effect of different irrigatins on bond strength of fiber posts cemented with RelyX U200. Eighty single-rooted premolars were sectioned at 14 mm from the apex, prepared with ProTaper Universal system until F3 instrument, and filled with F3 master cone and AH Plus sealer. Root canal filling was partially removed, remaining 4 mm of guta-percha at the apical third. Specimens were randomly divided into 8 groups (n=10), according to the irrigant used during root canal preparation and before fiber post cementation (dentin surface treatment), as described: SS: 0,9% saline solution (control group); CHX: 2% chlorhexidine; 1%NaOCl: 1% sodium hypochlorite; 2,5%NaOCl: 2,5% sodium hypochlorite; 5%NaOCl: 5% sodium hypochlorite; 1%CaOCl: 1% calcium hypochlorite; 2,5%CaOCl: 2,5% calcium hypochlorite; e 5%CaOCl: 5% calcium hypochlorite. For each group, irrigation was performed continuously with 2ml. Exacto N2 glass fiber posts were cemented with RelyX U200. The specimens were sectioned providing 3 slices, one for each root third and the push-out test was performed. Optical microscopy was used to analyze the failure mode. Bond strength means were calculated and ANOVA and Bonferroni tests were used for statistical analysis. SS showed higher mean of bond strength values (11.47MPa), than all NaOCl and CaOCl groups, which showed similar values to CHX (7.56Mpa ± 2:47). Adhesive failures at cement/dentin interface were predominant (58.33%). NaOCl and CaOCl negatively affect the bond strength of fiber posts to root dentine when cemented with sef-adhesive resin cement; however the concentration of NaOCl and CaOCl did not affect this outcome.Este estudo tem como objetivo avaliar o efeito de diferentes soluções irrigadoras sobre a resistência adesiva de pinos de fibra de vidro, cimentados com cimento autoadesivo RelyX U200. Foram utilizados 80 pré-molares inferiores humanos tiveram a coroa seccionada, padronizando-se o comprimento da raiz em 14 mm. Os condutos foram instrumentados com o sistema rotatório ProTaper até o instrumento F3, obturados com cimento endodôntico AH Plus e cones de guta-percha F3 do mesmo sistema, pela técnica do cone único. Os condutos foram desobturados até 10mm de profundidade, mantendo-se os 4mm apicais da obturação. As raízes foram aleatoriamente distribuídas em 8 grupos (n=10), de acordo com a solução irrigadora utilizada previamente à cimentação dos pinos: SS: solução salina 0,9% (grupo controle); CHX: clorexidina 2%; 1%NaOCl: hipoclorito de sódio 1%; 2,5%NaOCl: hipoclorito de sódio 2,5%; 5%NaOCl: hipoclorito de sódio 5%; 1%CaOCl: hipoclorito de cálcio 1%; 2,5%CaOCl: hipoclorito de cálcio 2,5%; e 5%CaOCl: hipoclorito de cálcio 5%. Para cada espécime, a irrigação foi realizada com 2ml da solução a cada troca de instrumento. Os pinos de fibra de vidro do Sistema Exacto Translúcido n02 foram silanizados e cimentados com o cimento resinoso autoadesivo RelyX U200. As raízes foram seccionadas na máquina de corte, de forma a obter 3 slices por espécime, sendo 1 slice para cada terço radicular. A seguir, os corpos de prova foram submetidos ao teste de push-out na máquina de ensaio universal EMIC. Para análise do padrão de falha, os espécimes foram analisados com microscopia óptica. A média de resistência adesiva de cada espécime foi calculada. Testes ANOVA e Bonferroni foram utilizados para analisar as diferenças entre os grupos. O grupo SS demonstrou a maior média de resistência adesiva, sendo superior aos grupos NaOCl e CaOCl (P <0.05), nos quais apresentaram valores semelhantes ao grupo CHX (7.56Mpa ± 2.47). As falhas adesivas cimento/dentina foram predominantes (58.33%). Concluímos que SS parece ser a solução mais adequada para limpeza do canal radicular previamente à cimentação de pinos de fibra cimentados com cimento autoadesivo RelyX U200. NaOCl e CaOCl diminuíram os valores de resistência adesiva dos pinos de fibra à dentina radicular e suas diferentes concentrações não afetaram este resultado.
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Pereira, Janaina Carla. "Efeito do tipo de cimento de fixação e configurações de retentores intra-radiculares na adesão à dentina radicular em diferentes profundidades." Universidade Federal de Uberlândia, 2007. https://repositorio.ufu.br/handle/123456789/16895.
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Fundação de Amparo a Pesquisa do Estado de Minas GeraisThis study evaluated the effect of different types of luting cement and post configuration on the bonding to intra-radicular dentin in different depths. One hundred and twenty roots received endodontic treatment and were post space preparation for fixation of glass fiber post in the configurations: serrated/parallel Reforpost X-Ray (S); and smooth/conical Exato Cônico (L). The posts were fixed with cements: RelyX ARC (ARC), RelyX Luting 2 (LU), RelyX Unicem (UN), Maxicem (MAX) and Cement-Post (CP). The roots were sectioned transversally, getting two disks of 1mm of thickness for third of the root portion: cervical (C), medium (M) and apical (A), and submitted to the micropush-out test with speed of 0.5mm/min. The bond strength values (MPa) were submitted to the analysis of variance in scheme of subdivided parcel and Tukey test (p0.05). There was significant difference among the cements types (p<0.0001), among the localizations (p<0.0001) and the interaction cement x localization was significant (p<0.0001). The post configuration did not influence the bond strength values. The cements LU and UN presented the highest values of bonding in all extension of root dentin. The cements ARC and CP presented similar bonding values in cervical third, however, the bond strength decreased in the crown-apex direction for the ARC. The cement MAX presented the lowest values of bonding.
Este estudo avaliou o efeito do tipo de cimento de fixação e da configuração de retentores intra-radiculares na adesão à dentina intra-radicular em diferentes profundidades. Cento e vinte raízes receberam tratamento endodôntico e foram aliviadas para fixação de retentores intra-radiculares de fibra de vidro nas configurações: serrilhado/paralelo Reforpost X-Ray (S); e liso/cônico Exato Cônico (L). Os pinos foram fixados com cimentos: RelyX ARC (ARC), RelyX Luting 2 (LU), RelyX Unicem (UN), Maxicem (MAX) e Cement-Post (CP). As raízes foram seccionadas transversalmente, obtendo-se 2 discos de 1mm de espessura por terço da porção radicular aliviada: cervical (C), médio (M) e apical (A), e submetidos ao teste de micropush-out com velocidade de 0,5mm/min. Os valores de resistência adesiva (MPa) foram submetidos à análise de variância em esquema de parcela subdividida e teste de Tukey (p<0,05). Houve diferença significativa entre os tipos de cimentos (p<0,0001), entre as localizações (p<0,0001) e a interação cimento x localização foi significativa (p<0,0001). A configuração do pino não influenciou nos valores de resistência adesiva. Os cimentos LU e UN apresentaram os maiores valores de adesão em toda extensão da dentina radicular. Os cimentos ARC e CP apresentaram valores de adesão no terço cervical semelhantes, contudo, a resistência adesiva decresceu no sentido coroa-ápice para o ARC. O cimento MAX apresentou os menores valores de adesão.
Mestre em Odontologia
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Salvador, Inês Isabel Feliciano. "Análise da capacidade de selamento de um cimento de obturação." Master's thesis, [s.n.], 2014. http://hdl.handle.net/10284/4388.
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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina DentáriaIntrodução: O sucesso no Tratamento Endodôntico depende da prevenção e controlo da infecção do canal radicular, o qual é obtido com uma limpeza adequada, conformação dos canais radiculares, preenchimento e selamento tridimensional. A micro-infiltração é considerada uma das causas que, com mais frequência, contribui para o fracasso do tratamento endodôntico sendo influenciada por muitas variáveis destacando-se, entre elas, as propriedades físicas e químicas dos cimentos obturadores. Outro fator muito importante que pode afetar o selamento é a desobturação parcial de um canal para colocação de um espigão intrarradicular. Objectivos: O estudo em questão tem como objetivo avaliar in vitro a infiltração apical em dentes parcialmente desobturados imediatamente após a obturação e em dentes parcialmente desobturados 8 dias após a obturação usando 2Seal® como cimento de obturação. Materiais e Métodos: Usou-se uma amostra de 40 dentes monocanalares os quais foram divididos em 4 grupos. Todos eles foram instrumentados com o sistema ProTaper®. Os dentes inseridos nos grupos I e II foram obturados com a técnica de condensação lateral, sendo que o primeiro grupo foi desobturado no mesmo dia em que a obturação foi efetuada e o segundo grupo 8 dias após. Os dois grupos restantes são os grupos controle positivo e negativo, que servem para atestar a ocorrência de infiltração apical, pelo foramen radicular. Para testar a micro-infiltração usou-se o método de penetração de corante, sendo o corante escolhido Azul-de-Metileno a 2%. Resultados: No grupo dos controlos positivos (grupo III) o corante infiltrou o comprimento total do dente, e no grupo dos controlos negativos (grupo IV) não se verificou qualquer tipo de infiltração. O grupo I apresenta uma microinfiltração média de 5,06 mm e o grupo II de 2,98 mm, com desvios padrão de 3,07 e 2,67, respetivamente. Conclusões: Após a recolha e análise dos dados concluiu-se neste estudo que em dentes obturados com a técnica de condensação lateral e com este cimento, a desobturação 8 dias após a obturação provoca significativamente menos micro-infiltração que uma desobturação imediata (p= 0.042). Sendo este um estudo in vitro é importante referir que os resultados obtidos podem não ser equivalentes na prática clínica. Não menos importante, é a necessidade de realizar mais estudos, com diferentes tempos de desobturação, diferentes cimentos obturadores e diferentes métodos de obturação, a fim de se perceber qual a influência destes fatores na quantidade de micro-infiltração apical. Possuir este conhecimento é fundamental para a decisão do clínico aquando da colocação de um espigão, de forma a selecionar as melhores condições para um selamento apical o mais satisfatório possível. Introduction: Success on the Endodontic Treatment depends on the prevention and infection control of the root canal, which is obtained through proper cleaning, root canal forming, filling and tridimensional sealing. Micro-infiltration is considered as one of the most frequent causes that leads to root canal treatment failure since it is influenced by many variables, mainly the sealing cement’s physical and chemical properties. Another important factor that might affect sealing is the partial removal of a canal’s filling to place a post. Aim: Evaluate in vitro apical infiltration on teeth whose obturation was immediately removed after being placed and on teeth unobturated 8 days after obturation using 2Seal® as sealing cement. Materials and methods: a sample of 40 single rooted teeth was used and divided into 4 groups. All teeth were instrumented with the ProTaper® system Teeth from group I and II were obturated with the lateral condensation technique, being the first group unobturated on the same day that they were obturated and the second group 8 days later. The two remaining groups are positive and negative control groups with the purpose to attest for the occurrence of apical infiltration through the radicular foramen. Microinfiltration was tested with the dye penetration method, being methylene blue at 2% the chosen dye. Results: in the positive control group (group III) the dye penetrated the entire length of the teeth, and the negative control group (group IV) there was not any kind of infiltration. Group I had an average microleakage 5.06 mm and 2.98 mm in group II, with standard deviations of 3.07 and 2.67, respectively. Conclusion: After the data collecting it was concluded that teeth obturated with lateral condensation technique and with this cement, unobturation 8 days after the obturation causes significantly less micro-infiltration when comparing with immediate unobturation (p= 0.042). Since this is an in vitro study it’s important to state that the results obtained might not be equivalent on clinical practice. Not less relevant is the necessity to address further studies using different desobturation times, different sealing cements and different obturation methods to understand the influence of these factores on the apical micro-infiltration’s quantity. This knowledge is fundamental for the professional’s decision when about to place a post and so that it’s possible to choose the best conditions for an apical sealing as satisfying as possible.
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Champagne, Jonathan. "Modélisation physique du comportement mécanique linéaire et non-linéaire des élastomères renforcés." Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLM043.
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L’ajout de charges dans les élastomères, en particulier les nano-silices dans les silicones, améliore sensiblement les propriétés mécaniques (rigidité, dissipation, contrainte à rupture,...). En contrepartie, cela introduit dans le comportement mécanique des dépendances et des non-linéarités absentes dans la matrice pure. Le lien entre la microstructure complexe du matériau et ses propriétés mécaniques macroscopiques n’est pas encore clairement établi. C’est pourquoi, nous commençons par construire un modèle stochastique décrivant la réponse mécanique linéaire des élastomères renforcés. Ce modèle est basé sur le concept de ponts vitreux. La microstructure représentative du matériau est formée par une distribution d’orientations et de longueurs de ponts, i.e. de régions de chaînes polymères confinées entre agrégats. Localement, la réponse mécanique du pont peut être vitreuse ou caoutchoutique selon le confinement, la température et l’amplitude de déformation. Les propriétés mécaniques macroscopiques de la distribution sont calculées par une méthode d’homogénéisation auto-cohérente. Pour chaque matériau, la distribution de ponts peut être identifiée à partir des mesures expérimentales du renforcement mécanique en régime linéaire.Le modèle stochastique nous permet aussi d’élucider l’origine physique de l’équivalence température-pression mise en évidence sur la rigidité. Alors que la température engendre la disparition des ponts vitreux (adoucissement), nous montrons que la pression, elle, en crée de nouveaux (rigidification). Le concept de ponts vitreux nous permet alors d’établir une nouvelle loi d’équivalence température-pression pour les élastomères renforcés. En outre, nous montrons que cette théorie décrit aussi, en première approximation, les propriétés mécaniques non-linéaires (effet Payne) de nos matériaux. Pour finir, nous mettons en œuvre dans un code de calcul éléments finis, un modèle de comportement macroscopique à base physique. Bien que le cadre thermodynamique soit classique, les valeurs des paramètres matériaux sont issues de surfaces de réponses qui sont identifiées à partir du modèle stochastiqueThe addition of fillers into a polymer matrix, such as nano-silica into silicone rubbers, brings an outstanding enhancement in the mechanical properties (stiffness, hysteresis, ultimate strength,...). In return, many dependencies or nonlinearities appear in the mechanical behaviour which do not exist in the pure rubber. The relation between the microstructure and the macroscopic mechanical properties is not yet clearly understood.Thus, we start with the development of a stochastic model describing the linear mechanical response of filled rubbers. This model is based on the glassy bridges theory. The typical microstructure of the system is composed by a bridges lengths and orientations distribution, i.e. confined polymer chains between aggregates. The local mechanical response of a single bridge can be glassy or rubbery depending on the confinement degree, the temperature and the strain amplitude. The macroscopic mechanical properties of the distribution are calculated by the mean of a self-consistent homogenization. For all our materials, the bridges distribution has been identified based on the linear mechanical reinforcement measurements.The stochastic model also provides the physical origin of the pressure-temperature superposition highlighted on the stiffness. The temperature makes the glassy bridges disappear (softening) while the pressure creates new ones (hardening). The glassy bridges theory allows us to suggest a new pressure-temperature superposition law for filled elastomers.Then, we show that the theory is also capable, to a first approximation, to describe the nonlinear mechanical properties (Payne effect) of our samples. Finally, we implement the constitutive equations of a macroscopique behaviour into a finite element software. Although the thermodynamical framework is standard, the material parameters are given by responses surfaces which are identified based on the stochastic model
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Klíč, Antonín. "Hierarchická řešení a struktura parametrů uspořádání v teroii středního pole pro spinová skla a příbuzné materiály." Doctoral thesis, 2013. http://www.nusl.cz/ntk/nusl-327199.
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We analyze the replica-symmetry-breaking (RSB) construction in the Sherrington - Kirkpatrick (SK) model and in the p-state Potts glass for p ≤ 4. We present a general scheme for deriving an asymptotic solution with an arbitrary number of discrete hierarchies of broken replica symmetry near the critical temperature for both models, and close to the de Almeida- Thouless instability line in the SK model. We show that in the SK model all solutions with finite many hierarchies are unstable and only the scheme with infinite many hierarchies becomes marginally stable in the spin-glass phase. For the Potts glass, we find, moreover, an one-step RSB solution which co- exists with the infinite RSB solution for p > p∗ ≈ 2.82. The former solution is locally stable but has lower free energy than the latter which is marginally stable and has the highest free energy. 1
Books on the topic "Potts glass"
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Blackman, Barbara. Glass after glass: Autobiographical reflections. Ringwood, Vic., Australia: Viking, 1997.
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Traylor, Gary. Chilled glass and hot pots: A helicopter story. Bellingham, Wash: Heliworld Press, 1987.
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Prater, Donald. A ringing glass: The life of Rainer Maria Rilke. Oxford: Clarendon, 1994.
Find full textBook chapters on the topic "Potts glass"
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Dillmann, O., W. Janke, and K. Binder. "MC Study of the p-state Mean-Field Potts Glass." In Springer Proceedings in Physics, 42–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-60095-1_7.
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Brangian, C., W. Kob, and K. Binder. "Monte Carlo Study of the Dynamic and Static Glass Transitions in the 10-State Potts Glass." In New Kinds of Phase Transitions: Transformations in Disordered Substances, 516–26. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0595-1_39.
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Scheucher, M., J. D. Reger, K. Binder, and A. P. Young. "Finite-Size Scaling Study of the Simple Cubic Three-State Potts Glass." In Springer Proceedings in Physics, 172–76. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76382-3_15.
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Tartara, Patrizia. "Along the Caeretan coast and forward on." In Proceedings e report, 127–36. Florence: Firenze University Press, 2020. http://dx.doi.org/10.36253/978-88-5518-147-1.14.
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The territory along the coast north-west of Ro me, still well preserved; in the Etruscan period was for the most under Caere control; it had the three important ports. The territory of Caere has been analyzed for a long time now, through an historical-topographic analytical study of the traces of archaeological remains. The research has been carried out by use of historical and recent aerial photographs and glass slides, last but not least the contribution of the monitoring aerial flights operated with the Carabinieri Helicopter Group of Pratica di Mare.
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Garwood, Samantha. "Producers, Intermediaries, and Consumers. The Role of Adriatic Ports in the Venetian Glass Trade." In Material Exchanges in Medieval and Early Modern Europe, 173–210. Turnhout, Belgium: Brepols Publishers, 2021. http://dx.doi.org/10.1484/m.hdl-eb.5.123739.
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Araújo, A. I., M. Martins, J. C. Reis Campos, A. Barros, A. Azevedo, and T. Oliveira. "Influence of the Er,Cr:YSGG laser and radial firing tips on the push-out bond strength of glass fiber posts." In Biodental Engineering V, 95–100. London, UK; Boca Raton, FL: Taylor & Francis Group, [2019] |: CRC Press, 2019. http://dx.doi.org/10.1201/9780429265297-19.
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Laird, Pamela Walker. "Parallel Ladders to the Glass Ceiling." In The President and American Capitalism Since 1945. University Press of Florida, 2017. http://dx.doi.org/10.5744/florida/9780813056524.003.0008.
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Chapter 8 compares the appointment of women in presidential cabinets to top executive positions in corporations. The author argues that the record of promoting women to CEO posts in corporate America has been inferior to their elevation in cabinet posts. Overall, in both civic and business arenas, glass ceilings continue to inhibit upward movement for women despite meritocratic rhetoric to the contrary.
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"38 Clinical Methods with Glass-fiber Posts." In Endodontology, edited by Michael A. Baumann and Rudolf Beer. Stuttgart: Georg Thieme Verlag, 2010. http://dx.doi.org/10.1055/b-0034-84604.
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Dickens, Charles. "Chapter XXXVIII Miss Tox Improves an Old Acquaintance." In Dombey and Son. Oxford University Press, 2008. http://dx.doi.org/10.1093/owc/9780199536283.003.0039.
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The forlorn Miss Tox, abandoned by her friend Louisa Chick, and bereft of Mr. Dombey’s countenance—for no delicate pair of wedding cards, united by a silver thread, graced the chimney-glass in Princess’s Place, or the harpsichord, or any of those little posts of display...
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Ellis, Jonathan. "Introduction: ‘For what is a letter?’." In Letter Writing Among Poets. Edinburgh University Press, 2015. http://dx.doi.org/10.3366/edinburgh/9780748681327.003.0016.
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The Introduction outlines the history and reception of poets’ letters from the Romantic period to the present day, what many epistolary critics might gloss as a journey from ‘the golden age of letter writing’ to the apparent eclipse of letter writing by e-mail. It also discusses the different ways in which letters have been represented and utilized by biographers and literary critics, as well as by prominent theorists such as Bakhtin and Derrida.
Conference papers on the topic "Potts glass"
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Golchert, B., S. L. Chang, C. Q. Zhou, and J. Wang. "Modeling of Regenerative Furnace Ports." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-42321.
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In order to increase overall efficiency, many industrial glass furnaces are regenerative; that is, the heat from the exhaust gases is used to preheat in the in-coming combustion air. The ports on these furnaces inject stream(s) of fuel into the preheated air stream and then combustion occurs inside the combustion chamber. Modeling of the exact detail of these furnace ports in addition to modeling the combustion space proper becomes computationally burdensome since many of these furnaces are extremely large. This paper presents an engineering approach using computational fluid dynamics to model both the major effects of the furnace ports in addition to calculating the detailed flow field in the combustion space. This approximation has been incorporated into a complete (combustion space/glass melt) furnace simulation. This engineering approach significantly reduces run time while still maintaining results that represent the conditions seen in the furnace. This paper will present this approach as well as some preliminary comparisons with actual furnace data/observations.
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Mandisloh, Kristin, Sven Achenbach, Timo Mappes, Tilmann Rogge, and Roman Truckenmueller. "Submicron Polymer Flow Cells." In ASME 4th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2006. http://dx.doi.org/10.1115/icnmm2006-96147.
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This paper investigates the fabrication processes of polymer micro channels integrated into flow cells. The cross sectional dimensions of these flow cell channels are in the range of microns containing structures or structure details in the submicron range. Single-component and double-component cells are presented. Single-component cells are entirely made of one polymer. They are composed of a micro structured substrate and a cover plate to hermetically seal the subjacent microfluidic structures. Flexible fluidic ports are added to facilitate interfacing. Polymethylmethacrylate (PMMA) is used as an industrially prefabricated foil (HESA®Glas VOS; HESA®Glas HESAlite). Double-component cells are made of spincoated PMMA (MicroChem 950k PMMA A11; AllResist GmbH 950k PMMA A9) that is micro structured on glass substrates prior to sealing with a cover plate. PMMA enables high resolution direct lithographic patterning of the fluidic structures. We apply Deep UV Lithography (DUV) to photochemically degrade PMMA and subsequently dissolve the degraded areas in an organic solvent. This process had previously primarily been utilized to pattern polymer waveguides. For minimum feature size devices, initial samples have been fabricated applying Deep X-Ray Lithography (DXRL) instead of DUV. Final sealing with PMMA cover plates is performed using thermal and UV bonding or solvent welding.
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Yazdi, Shahrzad H., Scott M. Davison, and Kendra V. Sharp. "Experimental Demonstration of Localized Flow Control in a Microchannel Using Induced-Charge Electroosmosis." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11480.
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In this paper we investigate the use of induced charged electroosmosis (ICEO) as a means of providing localized flow control within bulk pressure-driven flow. Conductive posts are positioned in a microchannel in such a way that an AC electric field can be applied across them. This AC field induces an electric double layer (EDL), leading to ICEO flow around the conductive object. A pressure gradient is applied across the length of the channel to drive a background flow past the ICEO region. The combination of AC and pressure-driven flow fields is expected to create recirculation regions around the posts which could be useful for trapping particles or focusing the flow, e.g. for lab-on-a-chip applications. Numerical models of ICEO flow were developed and used to provide guidance for the design of microfluidic devices. These numerical models were also used to explore the number, position and shape of the conducting posts to create useful flow patterns. However, this paper focuses on the fabrication of and experiments within a prototypical microdevice. The device was fabricated from silicon dioxide and conducting gold pillars positioned in the glass channel. Experimental results obtained from this device have demonstrated localized ICEO-based flow control. Specifically, wake regions devoid of particles are created behind the posts.
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Yang, Lung-Jieh, Tzu-Yuan Lin, and Yu-Cheng Ou. "A Thermopneumatic Valveless Micropump With PDMS-Based Nozzle/Diffuser Structure for Microfluidic System." In ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52352.
Full textAbstract:
A thermopneumatic valveless micropump with a PDMS-based nozzle/diffuser structure was firstly designed and realized herein by stacking three layers of PDMS on a glass slide. Unlike the conventional peristaltic pumping configuration, the new structure of the micropump consists of only one set of heater on the glass slide, a thermopneumatic actuation chamber, and an actuation diaphragm. Additionally, it includes a flowing channel with nozzle/diffuser structure and inlet/outlet ports. In this valveless microchannel, fluid is driven by asymmetric flow resistance produced from the nozzle and diffuser configuration. The actuation diaphragm between the gas-pneumatic chamber and the flowing channel can bend up and down due to the gas expansion as well as the thermal buckling of the PDMS diaphragm imposed from the heating in the gas-pneumatic actuation chamber.
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Choi, Chiwoong, DongIn Yu, and Moohwan Kim. "Aspect Ratio Effect on Adiabatic Two-Phase Flow in Rectangular Microchannels." In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18152.
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Most microscale thermal hydraulic systems have been used rectangular microchannels. In a rectangular microchannel, most important parameter is an aspect ratio. In this study, glass rectangular microchannels were fabricated using MEMS (micro-electro-mechanical system) fabrication techniques with a photosensitive glass. The width of all channels is same to approximately 500 μm and the height of rectangular microchannel was changed. The hydraulic diameters of the rectangular microchannels were 490, 322 and 143 μm. Experiments of adiabatic two-phase flow in the rectangular microchannels were conducted using liquid water and nitrogen gas. Pressure drop was directly measured from embedded pressure ports. And the pressure drop results were compared with correlations. Visualization of flow patterns were achieved with a high-speed camera and a long-distance microscope. Bubble behaviors were analyzed using visualized images based on a unit cell concept. As the aspect ratio decreased, a confinement effect was increased. And the thickness of liquid film in the corner of the rectangular cross section was reduced with the aspect ratio decreased. This result affected all phenomena of two-phase flow in the rectangular microchannels.
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Busch, Stephen, Maurice Kleindienst, Christoph Dahnz, Uwe Wagner, and Ulrich Spicher. "Design and Flow Analysis of a Novel Optically Accessible Heavy Duty Diesel Research Engine." In ASME 2011 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/icef2011-60024.
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A new single-cylinder optically accessible heavy duty diesel engine has been conceived and constructed at the Institut fu¨r Kolbenmaschinen. Rather than being made from a quartz glass cylinder, the cylinder liner of this engine is modified with three round, flat optical access ports to facilitate laser-optical measurements within the combustion chamber. The flat optical surfaces prove less problematic than a quartz glass cylinder in terms of internal reflections, cleaning procedures, cost, and robustness. A specially adapted piston facilitates the passage of the laser sheet into the piston bowl and provides a view into the bowl at top dead center. Computational fluid dynamics (CFD) simulations were performed in order to estimate the effects of the optically necessary piston and cylinder liner modifications on in-cylinder flow and to compare the flow characteristics with those simulated for a non-modified engine. Emphasis is placed on turbulence behavior before top dead center. The trade-offs and limitations inherent in the modified piston design are discussed in this context. Further optical investigations with this engine will provide insight into the mixture formation and combustion processes. In particular, the soot formation and oxidation processes will be studied under realistic engine operating conditions.
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Bielawski, Kevin S., and Nathan J. Sniadecki. "Cellular Traction Forces Measured With Microposts Made by Hot Embossing of Polystyrene." In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14568.
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Polydimethylsiloxane (PDMS) has become a highly utilized tool to study the forces that cells generate, although, outside of lab on chip devices, it is not widely used and requires protein coatings to encourage cell adhesion1. Furthermore, PDMS suffers from changes in composition and stiffness with different curing conditions2. Alternatively, polystyrene is a common substrate that promotes cell adhesion and has mostly consistent properties; however, polystyrene is typically challenging to form without special equipment and expensive molds. Previously, a hot embossing method3 has been proposed to manufacture polystyrene devices using a PDMS negative mold and polystyrene chips. A moderate amount of pressure and temperatures above the glass transition temperature of polystyrene enable the polystyrene to flow into the mold. In this paper, we fabricate microposts out of polystyrene and successfully seed cells on top of the posts.
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Jung, Jung-Yeul, and Ho-Young Kwak. "Novel Fabrication and Testing of a Bubble-Powered Micropump." In ASME 3rd International Conference on Microchannels and Minichannels. ASMEDC, 2005. http://dx.doi.org/10.1115/icmm2005-75015.
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A bubble-powered micropump was fabricated and tested in this study. The micropump consists of a pair of nozzle-diffuser flow controller and a pumping chamber. The two-parallel micro line heaters were fabricated to be embedded in the silicon dioxide layer above a silicon wafer which serves as a base plate for the micropump. The pumping chamber, the pair of nozzle-diffuser unit and microchannels including the liquid inlet and outlet port were fabricated by etching through another silicon wafer. A glass wafer having two holes of inlet and outlet ports of liquid serve as upper plate of the pump. The sequential photographs of bubble nucleation, growth and collapse were visualized by CCD camera. Clearly liquid flow through the nozzle during the period of bubble growth and slight back flow of liquid at the initial period collapsing can be seen. The mass flow rate was found to be dependent on the duty ratio and the operation frequency. The mass flow rate decreases as the duty ratio increases in the micropump with either circular or square pumping chamber.
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Matsushita, Shinichi, Chungpyo Hong, Yutaka Asako, and Ichiro Ueno. "Experimental Investigations of Turbulent Gas Flow in a Micro-Channel." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-63295.
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This paper presents experimental investigations on turbulent gas flow characteristics of nitrogen gas through a micro-channel. The micro-channels were etched into silicon wafers, capped with glass, and their hydraulic diameter is 147.76 micro meters. The micro-channel was designed with a main flow channel and seven side channels, which lead to the pressure transducers. The stagnation pressure was designated in such a way that the flow is in turbulent flow regime. The outlet of the channel faced to the atmosphere. The pressures of the main channel at seven locations were measured by gauge pressure transducers to determine local values of Mach number. And the pressure differences of each pressure ports were measured by differential pressure transducers to obtain the pressure losses precisely. The pressure distribution of turbulent gas flow through a micro-channel falls steeply and Mach number increases near the outlet with increasing the inlet pressure due to flow acceleration. Both Darcy friction factor and Fanning friction factor were obtained for turbulent flow. The result shows that the obtained both friction factors were evaluated as a function of Reynolds number on the Moody chart. The values of Darcy friction factors differ from Blasius correlation for turbulent flow regime due to the compressibility effects, however the values of Fanning friction factors coincide with Blasius correlation.
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Kingston, Todd A., and Theodore J. Heindel. "Visualization and Composition Analysis to Quantify Mixing in a Screw Pyrolyzer." In ASME 2013 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fedsm2013-16054.
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Characterizing the mixing effectiveness of systems or processes in granular applications is difficult due to ineffective sampling procedures and a lack of quantifiable measurement techniques. The mixing effectiveness of a screw pyrolyzer consisting of a binary mixture of 500–6350 μm red oak chips and 300–500 μm glass beads is evaluated using optical visualization and composition analysis techniques. The mass fraction of binary mixture samples is determined and the weighted sample variance from four outlet ports is used to evaluate the mixing effectiveness. The effect of dimensionless screw pitch on the mixing effectiveness is investigated at levels of p/D = 0.75, 1.25, and 1.75. Optical visualization is captured across the entire mixing region’s periphery allowing qualitative observations to be made, leading to the visual observation that increasing the dimensionless screw pitch increases the mixing effectiveness. Quantitative composition analysis utilizing a one-way analysis of variance (ANOVA) statistical model confirms that increasing the dimensionless screw pitch from 0.75 to 1.25 results in a significant increase in mixing effectiveness. However, diminishing increases in mixing effectiveness were shown as the dimensionless screw pitch increased from 1.25 to 1.75, and statistically these two conditions could not be distinguished given the amount of data in this study. Results are compared to previous granular mixing measurement techniques found in the literature, and similar results are reported.