Academic literature on the topic 'Superficie minima'
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Journal articles on the topic "Superficie minima"
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Flores-Stulzer, Eunice, Narcy Villalobos-Sandí, Lilliana Piedra-Castro, and Carola Scholz. "Evaluación breve de la presencia de diatomeas y su relación con algunos parámetros físico-químicos en el río Pirro, Heredia, Costa Rica." Uniciencia 31, no. 2 (July 29, 2017): 99. http://dx.doi.org/10.15359/ru.31-2.7.
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La evaluación de la calidad de agua en ecosistemas fluviales en áreas urbanas en el trópico, basada en la utilización de diatomeas, es escasa. Este estudio exploratorio pretendió establecer la composición y riqueza de especies de diatomeas en relación con los parámetros físicos químicos como elemento base para un monitoreo de la microcuenca urbana del río Pirro, Heredia, Costa Rica. Los materiales se colectaron en la parte alta, media y baja del río durante la época seca, lluviosa y de transición. Se analizó el pH, el oxígeno disuelto, la conductividad, la temperatura y la composición de diatomeas raspando una superficie de 20 cm x 20 cm de rocas. Se observaron 18 especies de diatomeas con poca abundancia, con presencia de Navicula seminulum, N. minima y N. cryptotenella que son indicadoras de condiciones moderadas de contaminación y del género Nitzschia que presenta especies tolerantes a contaminantes. La mayor diversidad de especies de diatomeas ocurrió en la época lluviosa y se observaron diferencias significativas entre las épocas del muestreo y la riqueza de especies. Se concluye, con base en la presencia de especies, que el río Pirro presenta condiciones sanitarias malas y que el cauce bajo es el sitio más afectado por la contaminación. Pero es necesario aumentar la información en esta temática.
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Dematteis, Bruno, and Esteban I. Meza Torres. "Helechos y licofitos de la Reserva Natural Educativa Colonia Benítez (Chaco, Argentina)." Bonplandia 24, no. 1 (January 1, 2015): 27. http://dx.doi.org/10.30972/bon.241206.
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La Reserva Natural Educativa Colonia Benítez cuenta con una superficie aproximada de ocho ha, está ubicada en el departamento Primero de Mayo, en la provincia del Chaco, Argentina. Desde el punto de vista fitogeográfico, esta área protegida se localiza dentro del Distrito Chaqueño Oriental de la Provincia Chaqueña. Como objetivos de este trabajo se planteó realizar un inventario de helechos y licofitos y una clave para el reconocimiento de los taxa que crecen en esta reserva. A tal fin, se examinaron las colecciones depositadas en CTES, y se realizaron nuevas recolecciones de especímenes. Se registraron 12 géneros con un total de 17 especies, siendo Doryopteris el género mejor representado con tres especies: D. concolor, D. lorentzii y D. pentagona. El género Adiantopsis presentó dos especies (A. chlorophylla y A. tweediana), al igual que Anemia con (A. simplicior y A. tomentosa var. anthriscifolia) y Pteris (Pteris denticulata var. tristicula y Pteris vittata). Los demás géneros presentaron sólo una especie: Adiantum lorentzii, Anogramma chaerophylla, Azolla cristata, Hemionitis tomentosa, Microgramma vaccinifolia, Pityrogramma calomelanos var. calomelanos, Pleopeltis minima y Selaginella sellowii. El hábito terrícola fue el mejor representado con 12 especies, de las cuales una de ellas es rupícola y otras tres se pueden comportar como epífitos facultativos, en tanto que los estrictamente epífitos fueron representados por sólo dos especies. Azolla cristata fue la única especie acuática presente. Se presentan observaciones ecológicas y un análisis biogeográfico de las especies registradas
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Rajaee, Saeed, Mehrdad Nasernejad, and Ibrahim Al-Ayyoub. "Superficial ideals for monomial ideals." Journal of Algebra and Its Applications 17, no. 06 (May 23, 2018): 1850102. http://dx.doi.org/10.1142/s0219498818501025.
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Let [Formula: see text] and [Formula: see text] be two ideals in a commutative Noetherian ring [Formula: see text]. We say that [Formula: see text] is a superficial ideal for [Formula: see text] if the following conditions are satisfied: (i) [Formula: see text], where [Formula: see text] denotes a minimal set of generators of an ideal [Formula: see text]. (ii) [Formula: see text] for all positive integers [Formula: see text]. In this paper, by using some monomial operators, we first introduce several methods for constructing new ideals which have superficial ideals. In the sequel, we present some examples of monomial ideals which have superficial ideals. Next, we discuss on the relation between superficiality and normality. Finally, we explore the relation between normally torsion-freeness and superficiality.
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Harris, R. L., and H. Daya. "Closed rhinoplasty approach for excision of nasal dermoids." Journal of Laryngology & Otology 124, no. 5 (December 11, 2009): 538–42. http://dx.doi.org/10.1017/s002221510999243x.
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AbstractObjective:To assess the efficacy of excision of nasal dermoids through a closed rhinoplasty incision. This is the first description of the use of this approach for excision of superficial nasal dermoids.Methods:Three boys aged five, nine and 12 years presented with midline nasal dermoids with minimal cutaneous involvement. Magnetic resonance imaging demonstrated distinct, cystic, superficial nasal masses. The cysts were excised through a closed rhinoplasty approach. In each case, completeness of extirpation was judged by histopathological examination of the excised specimen. Aesthetic outcome was recorded photographically.Results:All three patients' cysts were completely excised, with excellent cosmetic results.Conclusions:The closed rhinoplasty incision is another approach in the surgeon's armamentarium for excision of small, superficial nasal dermoid cysts. In well selected cases, this approach gives optimal cosmetic results, provides adequate exposure with minimal dissection, and allows total extirpation.
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Bacos, Jonathan T., and Steven H. Dayan. "Superficial Dermal Fillers with Hyaluronic Acid." Facial Plastic Surgery 35, no. 03 (June 2019): 219–23. http://dx.doi.org/10.1055/s-0039-1688797.
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AbstractMinimally invasive aesthetic procedures with hyaluronic acid filler have increased drastically since their development in 1989. Patients' desires to avoid surgery and achieve rapid results with minimal recovery led to a transformation in facial plastic surgery, demanding that aesthetic surgeons become proficient in nonsurgical augmentation. Over the years, new hyaluronic acid filler products were developed with different intrinsic properties, allowing clinicians to better treat different deficiencies of the face, reduce postprocedural pain, and optimize outcomes. The purpose of this article is to review the current state of nonsurgical facial plastic surgery with the superficial dermal filler, hyaluronic acid.
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Lund, Iréne, and Thomas Lundeberg. "Are Minimal, Superficial Or Sham Acupuncture Procedures Acceptable as Inert Placebo Controls?" Acupuncture in Medicine 24, no. 1 (March 2006): 13–15. http://dx.doi.org/10.1136/aim.24.1.13.
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Most controlled trials of acupuncture have used minimal, superficial, sham, or ‘placebo’ acupuncture. It has recently been demonstrated that light touch of the skin stimulates mechanoreceptors coupled to slow conducting unmyelinated (C) afferents resulting in activity in the insular region, but not in the somatosensory cortex. Activity in these C tactile afferents has been suggested to induce a ‘limbic touch’ response resulting in emotional and hormonal reactions. It is likely that, in many acupuncture studies, control procedures that are meant to be inert are in fact activating these C tactile afferents and consequently result in the alleviation of the affective component of pain. This could explain why control interventions are equally effective as acupuncture in alleviating pain conditions that are predominantly associated with affective components such as migraine or low back pain, but not those with a more pronounced sensory component, such as osteoarthritis of the knee or lateral epicondylalgia.
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Marquardt, G., R. Wolff, U. Schick, and R. Lorenz. "CT-Based Needle Marking of Superficial Intracranial Lesions for Minimal Invasive Neurosurgery." Acta Neurochirurgica 142, no. 5 (April 28, 2000): 583–85. http://dx.doi.org/10.1007/s007010050473.
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Hickerson, R. P., M. J. Conneely, S. K. Hirata Tsutsumi, K. Wood, D. N. Jackson, S. H. Ibbotson, and E. Eadie. "Minimal, superficial DNA damage in human skin from filtered far‐ultraviolet C." British Journal of Dermatology 184, no. 6 (March 2021): 1197–99. http://dx.doi.org/10.1111/bjd.19816.
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Wilson, Lynn D., Barry M. Kacinski, and Glenn W. Jones. "2174 Local superficial radiotherapy in the management of minimal stage IA Mycosis Fungoides." International Journal of Radiation Oncology*Biology*Physics 39, no. 2 (January 1997): 327. http://dx.doi.org/10.1016/s0360-3016(97)80941-8.
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BRANOVACKI, G., M. HANSON, R. CASH, and M. GONZALEZ. "The Innervation Pattern of the Radial Nerve at the Elbow and in the Forearm." Journal of Hand Surgery 23, no. 2 (April 1998): 167–69. http://dx.doi.org/10.1016/s0266-7681(98)80166-6.
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Sixty paired cadaver forearms were dissected to examine the distribution of the radial nerve branches to the muscles at the elbow and forearm. Emphasis was placed on the innervation of the extensor carpi radialis brevis and the supinator muscles because of discrepancies in the literature concerning these muscles. The most common branching pattern (from proximal to distal) was to brachioradialis, extensor carpi radialis longus, superficial sensory, extensor carpi radialis brevis, supinator, extensor digitorum/extensor carpi ulnaris, extensor digiti minimi, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus and extensor indicis. The branch to extensor digitorum and extensor carpi ulnaris came off as a common stem often with the branch to extensor digiti minimi. The branch to the ECRB muscle was noted to arise from the posterior interosseous nerve in 45%, superficial sensory nerve in 25% and at the bifurcation of the posterior interosseous and superficial sensory nerves in 30% of specimens. The supinator had an average of 2.3 branches from the posterior interosseous nerve (range 1–6). The branches to the supinator showed a wide variability proximal to and within the supinator.
Dissertations / Theses on the topic "Superficie minima"
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Carboni, Lucrezia. "Superfici minime tra matematica e architettura." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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Il problema di Plateau richiede di trovare tra tutte le superfici con un assegnato contorno quella di area minima. Le superfici soluzione di tale problema godono di una proprietà geometrica particolare: ogni punto della superficie ha curvature principali opposte. Le superfici che soddisfano quest’ultima proprietà si dicono superfici minime. Anche l’architettura ha fatto ampio uso di tali superfici, sia per la proprietà di assicurare un equilibrio stabile, sia perché permettono di contenere i costi in termini di minor materiale utilizzato, ma anche per la loro eleganza. In questo studio si riprendono alcuni dei concetti e dei principali risultati della geometria differenziale necessari per dare, nel secondo capitolo, una definizione rigorosa di superficie minima e di studiarne le principali proprietà. Successivamente, si studiano alcuni esempi di superfici minime, quali la superficie di Catalan, l’elicoide, unica superficie rigata non banale, e la catenoide, unica superficie minima di rotazione. Nel terzo capitolo vengono analizzati alcuni esempi di applicazione delle superfici minime in architettura.
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Avila, Luciana Maria Dias de. "Superficies minimas conjugadas e superficies minimas associadas." [s.n.], 1999. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307221.
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Orientador: Irwen Valle GuadalupeDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
Made available in DSpace on 2018-07-25T16:31:15Z (GMT). No. of bitstreams: 1 Avila_LucianaMariaDiasde_M.pdf: 2968227 bytes, checksum: 76d65974ec2f1e8c2a54b245f851ea99 (MD5) Previous issue date: 1999
Resumo: Neste trabalho estudamos superfícies mínimas conjugadas de uma superfície mínima e as propriedades geométricas que lhes são comuns; estudamos também superfícies mínimas associadas. Construção de superfícies mínimas como solução do problema de Björling também é estudado. Exemplos de superfícies mínimas e suas superfícies mínimas associadas são ilustrados, bem como exemplos de superfícies que são soluções do problema de Björling
Abstract: In this work we study conjugate minimal surfaces of a minimal surface and their geometric properties; we also study associated minimal surfaces. Construction of minimal surfaces are given as solution to the Björling's problem. Examples of minimal surfaces and their associated minimal surfaces are illustrated, as well as examples of surfaces that are solutions to the Björling's problem
Mestrado
Mestre em Matemática
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Giampieretti, Linda. "Superfici minime." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/5167/.
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Ricciardo, Antonio. "Superfici Minime." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4450/.
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Siciliano, Giuseppe. "Le superfici minime." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/2839/.
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Secreti, Nicola. "Superfici minimali." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16864/.
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Questa tesi è dedicata allo studio delle superfici minimali nello spazio euclideo R3. Oggi questa teoria ha una vasta gamma di applicazioni in vari settori della ricerca, quali la chimica, la biologia e l' architettura. Le origini della teoria delle superfici minimali possono essere ricondotte al 1744 con gli studi di Eulero e Lagrange. Eulero mostrò che la catenoide è una superficie minimale, e Lagrange scrisse l'equazione alle derivate parziali che deve essere soddisfatta affinchè una superficie della forma z = F(x,y) sia minimale. Nel 1776, Meusnier riscoprì la catenoide e mostrò che anche l'elicoide è una superficie minimale. Il mondo matematico dovette aspettare poi più di 50 anni prima che fossero scoperti nuovi esempi da Scherk. Il problema che diede spunto e importanza allo studio di queste superfici fu il cosidetto "Problema di Plateau", cioè quello di trovare, tra tutte le superfici aventi delle curve date come bordo, quella con area minima. Il lavoro è stato suddiviso in tre capitoli: il primo capitolo è un semplice riepilogo di elementi e risultati di base, utili per la trattazione dell'argomento. In particolare si richiamano i concetti di superficie regolare, spazio tangente, area e curvatura media (geometria differenziale); e di funzioni olomorfe, armoniche (analisi complessa). Il secondo capitolo presenta le superifici minimali, ne spiega le principali proprietà e ne espone qualche esempio. In particolare si fa attenzione alla differenza tra superfici minimali, così come sono definite, e le superfici di area minima, quelle che risolvono il "Problema di Plateau". Tra gli esempi presentati vi sono: elicoide e catenoide (isometriche tra loro), superfici di rotazione, Enneper e Scherk. Nel terzo ed ultimo capitolo vi è una trattazione abbastanza approfondita dei legami tra superfici minimali e le funzioni olomorfe.
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Lopes, Lauriclecio Figueiredo. "Superficies minimas folheadas por circunferencias." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/306661.
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Orientador: Valerio Ramos BatistaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
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Resumo: Entende-se por superfícies mínimas aquelas cuja curvatura média é nula. Têm-se como exemplos clássicos o catenóide, o helicóide e a superfície de Scherk. Historicamente, elas estão relacionadas com minimização de área, porém quando realiza-se uma variação normal incluindo os bordos, a superfície original com curvatura média nula pode representar uma área localmente máxima. Em certos casos de variação com bordo fixo, tem-se realmente a minimização do funcional área. No espaço euclidiano tridimensional, o Teorema da Representação de Weierstrass expressa uma superfície mínima em termos de integrais envolvendo uma função holomorfa e uma meromorfa. A partir desta meromorfa pode-se deduzir a aplicação normal de Gauss. Conceitos como curvatura Gaussiana, curvatura total, superfícies completas e regularidade também são utilizados para deduzir propriedades das superfícies mínimas. Quando estudamos as superfícies mínimas para as quais o bordo consiste de duas circunferências disjuntas, os Teoremas de Enneper e Shiffman, o Princípio de Reflexão de Schwarz e a unicidade do Problema de Bjõrling são ferramentas importantes para a dedução das soluções, a saber, o catenóide e as superfícies de Riemann. Estas apresentam simetrias por reflexão a um plano e invariância por rotação de 180 graus em torno de uma reta. A função "P de Weierstrass" simétrica é de grande utilidade no estudo destas propriedades
Abstract: Minimal surfaces are known to be the ones with mean curvature zero. Classical exampIes are the catenoid, helicoid and the Scherk surface. Historically, they were associated with the property of minimizing area. However, they can even maximize it localIy for cases of normal variation which include the boundary. For fixed boundary, we shalI analyse when they realIy minimize the area functional. In the three-dimensional Euclidean space, the Weierstrass Representation Theorem expresses any minimal surface S by means of integraIs with a holomorphic and a meromorphic functions, usualIy denoted by f and g, respectively. The unitary normal N of S is fulIy determined by g. Concepts like "Gaussian curvature", "total curvature", "com pleteness" and "regularity" are also employed in order to read off some properties of minimal surfaces. Concerning the case for which the boundary of S consists of two disjoint circumferences, Enneper's and Shiffman's Theorems, The Schwarz's Reflection PrincipIe and the B6rling's Problem are fundamental tools to characterize the solutions, namely the catenoid and the Riemann's examples. AlI these are invariant by a reflectional symmetry in a plane, and also by a rotation of 180-degree around a straight line. The symmetric Weierstrass-Pfunction is very useful to deduce these properties
Mestrado
Matematica
Mestre em Matemática
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Gneri, Paula Olga. "Superficies minimas no grupo de Heisengerg." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307111.
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Orientadores: Francesco Mercuri, Irene Ignazia OnnisDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
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Resumo: o objetivo deste trabalho é o estudo dos gráficos mínimos no grupo de Heisenberg de dimensão três. Primeiramente fizemos uma descrição deste grupo como grupo de Lie e sua álgebra de Lie. Verificamos que a aplicação exponencial é um difeomorfismo global entre a álgebra de Lie e o grupo de Heisenberg. Seguindo o ciclo natural, passamos a estudar a geometria Riemanniana do grupo de Heisenberg com métrica invariante à esquerda, calculando os campos invariantes à esquerda, as curvaturas, as geodésicas, os campos de Killing e o grupo de isometrias deste espaço. Subseqüentemente, estudamos a aplicação normal de Gauss para gráficos no grupo de Heisenberg, concluindo, entre outras propriedades, a não existência de superfícies totalmente umbílicas neste grupo. Classificamos todas as superfícies mínimas cujo posto da aplicação de Gauss é zero ou um e concluindo que tais superfície são regradas. Finalizando, analisamos alguns exemplos de gráficos mínimos completos cuja aplicação de Gauss tem posto dois. A classificação de gráficos mínimos com aplicação de Gauss de posto dois é ainda um problema em aberto
Abstract: The purpose of this work is study minimal surfaces in tri-dimensional Heisenberg group. Firstly, we made a description of Heisenberg group as Lie group and its Lie algebra. We examined that the exponential application is a global difeomorfism between Lie algebra and Heisenberg group. Thereafter, we investigate Riemann Geometry of left invariant metric Heisenberg group, weconsider left invariant fields, curvatures, geodesics, Killing fields and isometry group of this space. Subsequently, we examined the Gauss normal application to surfaces in Heisenberg group and weconclude a series of peculiarity as, for example, the not existence of umbilic surfaces in this group. We classified all minimal surfaces with rank-zero Gauss application ar rank-one Gauss application and we conclude that these surfaces are ruled. To put an end, we analyzed some examples of complete minimal surfaces with rank-two Gauss application. The classification of minimal surfaces with rank-two Gauss application is a open problem
Mestrado
Mestre em Matemática
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Caporale, Roberto. "Problema di Plateau e superfici minime." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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Il problema di Plateau, che prende il nome dal fisico belga Joseph Plateau, consiste nella ricerca della superficie che, tra tutte quelle aventi un determinato bordo, abbia area minima.
Già nel 1744 Eulero si era proposto di cercare la superficie di area minima avente come bordo due circonferenze poste su piani paralleli i cui centri appartengono ad una retta ortogonale ad entrambi. Tale superficie è la catenoide.
Molti matematici cercarono soluzioni del problema di Plateau: Lagrange nel 1762, introdusse il termine superfici minime e determinò l'equazione che doveva essere soddisfatta dalle superfici di area minima, la cosiddetta equazione di Eulero-Lagrange;
Mesnieur nel 1776 scoprì un'altra superficie minima, l'elicoide e dimostrò che le superfici di area minima hanno curvatura media nulla in ogni punto.
Monge nel 1783 dimostrò che, nel caso di superfici esprimibili come grafico di funzioni differenziabili, superfici con curvatura media nulla e superfici di area minima coincidono.
Solo nei primi anni del '900 si ebbero soluzioni generali del problema di Plateau, grazie ai lavori di Tibor Radò e Jesse Douglas. Quest'ultimo venne premiato nel 1936 con la medaglia Fields.
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Alessio, Osmar. "Linhas assintoticas em superficies minimas de R3." [s.n.], 1998. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307222.
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Orientador: Irwen Valle GuadalupeDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
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Resumo: Configurações de linhas assintóticas ao redor de pontos planares (ou flat) de superfícies mínimas são estudados. Modelos analíticos para essas configurações ao redor de pontos planares isolados e tipos particulares de fins são exibidos. Exemplos ilustrando todos os possíveis casos são também dados.
Mestrado
Mestre em Matemática
Books on the topic "Superficie minima"
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Pouillaude, Frédéric. Mallarmé: Deciphering the Stage. Translated by Anna Pakes. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780199314645.003.0005.
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This chapter draws out some minimal or superficial effects of Stéphane Mallarmé’s writings on dance, and of his other prose texts which mention dance tangentially. The first thing to note is that, as the chapter title suggests, these texts are scribbled at the theatre and only ever envisage dance within the horizon of the stage, even if the latter is ultimately presented as a perverse and banal location. There is no primitive dance in Mallarmé, then. But nor is there dance detached from the gaze which establishes it as such. Hence, there is nothing that ever escapes the conventional artifice of theatrical spectacle.
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Freeman, Samuel. Illiberal Libertarians. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190699260.003.0003.
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This chapter situates three contemporary views—classical liberalism, the high liberal tradition, and libertarianism—on the map of political conceptions and argues that, though libertarianism is normally considered to be a liberal view, the resemblance between liberalism and libertarianism is superficial. Correctly understood, libertarianism resembles a view that liberalism historically defined itself against, the doctrine of private political power that underlies feudalism. Like feudalism, libertarianism conceives of justified political power as based in a network of private contracts. It rejects the idea, essential to liberalism, that political power is a public power that is to be impartially exercised for the common good. Moreover, the primary institutions endorsed by the liberal political tradition—basic rights and liberties, equality of opportunity, and government’s role in supporting efficient markets, public goods, and a social minimum—are incompatible with libertarianism.
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Jovic, Sebastián Miguel. Geología y metalogénesis de las mineralizaciones polimetálicas del área El Tranquilo (Cerro León), sector central del Macizo del Deseado, provincia de Santa Cruz. Editorial de la Universidad Nacional de La Plata (EDULP), 2010. http://dx.doi.org/10.35537/10915/4346.
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La presente investigación tiene como eje principal el estudio detallado de las mineralizaciones y la geología de un área del Macizo del Deseado con características geológicas y metalogénicas únicas. La elección del área del El Tranquilo o también conocido como “anticlinal” El Tranquilo, como zona de estudio, se ha basado en el reducido conocimiento y la presencia características atípicas en las mineralizaciones y la escasa representación, en el Macizo del Deseado, de las rocas y unidades geológicas aflorantes. La investigación ha sido realizada en tres etapas: una primera con recopilación de antecedentes y trabajo de campo, una segunda analítica con trabajos de laboratorio y una tercera etapa interpretativa. Se realizó el procesado de imágenes satelitales (TM, SPOT, IKONOS) y se ejecutaron mapeos geológico-estructurales de detalle y semidetalle (con elaboración de una cartografía digital), descripción de testigos de sondeos (gran parte de los 30.000 metros de las perforaciones ejecutadas en la propiedad minera), se realizaron estudios petrográficos, calcográficos, de rayos X, determinaciones geoquímicas, estudios de inclusiones fluidas, de microscopía electrónica, microsonda electrónica, determinaciones geocronológicas y análisis de isótopos estables e inestables. Además se participó de otros trabajos complementarios realizados durante las distintas etapas de exploración minera, tales como geoquímica de suelos, muestras de trincheras y relevamientos magnetométricos y geoeléctricos terrestres y la interpretación, para la zona de trabajo, de estudios previos de magnetometría aérea y líneas sísmicas. El área del “anticlinal” El Tranquilo, está caracterizada por la presencia de rocas y unidades geológicas con escasa representación en el Macizo del Deseado, y representa una “ventana geológica” que permite el estudio del intervalo Triásico superior - Jurásico inferior, períodos que se encuentran poco expuestos en esta provincia geológica. La secuencia estratigráfica de este sector se inicia con las sedimentitas continentales, areniscas a areniscas conglomerádicas con intercalaciones de pelitas, del Grupo El Tranquilo, del Triásico medio a superior (Jalfin y Herbst 1995). Por encima, se presentan las rocas volcaniclásticas de la Formación Roca Blanca (Herbst, 1965), del Jurásico inferior. Esta es la litología más desarrollada en el área y está compuesta por tufitas, areniscas y sabulitas ricas en componentes volcánicos. Intruyendo a las sedimentitas continentales y a las tufitas, se disponen rocas básicas a intermedias del Jurásico inferior, que se presentan como filones capa de diabasa en el sector este del área y como pórfidos andesíticos de formas subcirculares en el sector noroeste, de la Formación Cerro León (Panza, 1995 y de Barrio et al., 1999). En los sectores norte y noreste del área afloran volcánitas del Jurásico medio a superior, basaltos y andesitas de la Formación Bajo Pobre, y en el sector sudoriental pequeños asomos de ignimbritas riolíticas del Grupo Bahía Laura (Panza, 1995). Estas unidades se encuentran parcialmente cubiertas por el Basalto Las Mercedes del Cretácico superior y el Basalto Cerro del Doce correspondiente al Eoceno (Panza, 1982) y finalizan esta secuencia sedimentos modernos, aluviales, coluviales y de bajos. En la presente investigación se determinó la presencia de niveles ignimbríticos ácidos y coladas basálticas intercaladas en las tufitas de la Formación Roca Blanca. A partir de las edades obtenidas, relaciones estratigráficas y composición se desvincula a los intrusivos dioríticos de la Formación Cerro León y se los asocia con el magmátismo de la Formación La Leona (Jurásico inferior). Los basaltos aflorantes en el área presentan características de basaltos continentales que se corresponden a los primeros indicios del magmatismo sinextensional jurásico y representan magmas básicos de origen mantélico que alcanzaron la superficie. Se los desvinculan de la Formación Bajo Pobre por ser ligeramente más antiguos al estar intercalados entre las tufitas de la Formación Roca Blanca (Jurásico inferior) y por presentar diferentes características isotópicas y petrogenéticas. Se define así una nueva unidad formacional para estas rocas denominándolas Formación El Piche. Los pórfidos andesíticos de la Formación Cerro León y las andesitas de la Formación Bajo Pobre presentan similitudes geoquímicas, isotópicas, petrogenéticas y edades semejantes, por lo que se interpreta un mismo origen para estas rocas, siendo los pórfidos andesíticos partes de los conductos de emisión de las coladas andesíticas. A diferencia del resto del Macizo del Deseado donde predomina casi por completo deformación con comportamiento netamente frágil, en el área de estudio se reconoció deformación tanto dúctil como frágil en las secuencias triásicas y jurásicas. Los rasgos estructurales más sobresalientes son: un domamiento regional de entre 15 a 20 km de diámetro, definido por Di Persia (1956) como “anticlinal” El Tranquilo, domamientos y plegamientos con dimensiones menores a 1 km localizados dentro de la antiforma regional, un sistema de fracturas radiales asociado al domamiento y la falla El Tranquilo con un sistema de vetas controladas por fallas. Se determinó que el “anticlinal” El Tranquilo, se formó por el emplazamiento de un cuerpo intrusivo no aflorante del orden de 8 a 10 Km de diámetro y profundidad mínima hasta su techo de 1400 m, subyaciendo al Grupo El Tranquilo y a la Formación Roca Blanca, y generando por su intrusión, el domamiento regional y los domamientos y plegamientos con dimensiones menores a 1 km localizados corresponde a una deformación producida por lacolitos o stocks no aflorantes. En el área de estudio se reconocieron gran cantidad de mineralizaciones, las que totalizan ~80 km lineales de vetas, ubicadas principalmente en el sector central del área. Las vetas se concentran hacia el este de la estructura regional, la falla El Tranquilo, son subparalelas a esta estructura y están emplazadas en las tufitas de la Formación Roca Blanca y pelitas y areniscas del Grupo El Tranquilo. Se han discriminado dos tipos distintos de vetas según su composición y expresión superficial, vetas formadas por importantes zonas de oxidación que representan la expresión superficial de vetas de sulfuros, y vetas, brechas hidrotermales, vetillas y stockworks formados principalmente por cuarzo. A partir de las distintas características observadas y datos obtenidos (composición, signatura geoquímica, mineralogía, datos de inclusiones fluidas, isótopos, controles estructurales y litológicos y edades) se ha podido diferenciar dos estilos de mineralización. La mineralización polimetálica que presenta una compleja mineralogía de sulfuros asociada a una signatura geoquímica de In, Cu, Au, As, Sn, W, Bi, Zn, Pb, Ag, Cd y Sb. Las temperaturas y salinidades de los fluidos indican un sistema epitermal para la formación de estas vetas. Su génesis esta vinculada a los cuerpos intrusivos dioríticos reducidos por sedimentos ricos en materia orgánica, concentrando en los fluidos hidrotermales In, Sn, Ag, W, Bi. Se define a esta mineralización como un depósito epitermal vetiforme polimetálico rico en In semejante a los depósitos de Japón y Bolivia. Las características de esta mineralización y la edad Jurásica inferior (193 Ma) confirman la presencia de un nuevo tipo de deposito epitermal que difiere del clásico modelo de baja sulfuración del Macizo del Deseado y que no se encuentra asociado al importante volcanismo bimodal del Jurásico medio a superior (Complejo Bahía Laura), como la mayoría de las mineralizaciones del Macizo del Deseado. Este hecho potencia el hallazgo de otros tipos de depósitos epitermales polimetálicos, asociados a otras rocas y con diferentes asociaciones metalogénicas. La mineralización argentífera está formada por cuarzo, carbonatos y en menor medida sulfuros y sulfosales con una signatura geoquímica de Ag (Au), Pb, Cu y Zn. Las temperaturas y salinidades de los fluidos indican un sistema epitermal para la formación de estas vetas. Su génesis está vinculada al magmatismo intermedio de las Formaciones Cerro León y Bajo Pobre, atribuyéndole una edad Jurásica media (168 Ma). Según sus características esta mineralización puede ser definida como un depósito epitermal de sulfuración intermedia. Esta mineralización también representa una variación en el modelo de baja sulfuración del Macizo del Deseado, pero está genéticamente asociada al volcanismo bimodal del Complejo Bahía Laura (Fm. Bajo Pobre) por lo que podría incluirse dentro de las mineralizaciones de la Provincia auroargéntifera del Deseado.
Book chapters on the topic "Superficie minima"
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Katzur, J., and F. Liebner. "Effects of Superficial Tertiary Dump Substrates and Recultivation Variants on Acid Output, Salt Leaching and Development of Seepage Water Quality." In Acidic Mining Lakes, 251–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-71954-7_13.
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Rocco Jr., Leopoldo. "Disintegration of Liquid Sheet Produced by Swirl Injector." In Energetic Materials Research, Applications, and New Technologies, 133–45. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2903-3.ch006.
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The development of liquid sheets that emerges from nozzles is influenced mainly by their initial speed and by the physical properties of the liquid and the ambient gas. A minimum speed of the sheet is necessary for its enlargement against the superficial tension that tends to contract the surface. As this speed increases, the sheet expands until a main extremity is formed, where balance exists among the superficial tension and the inertial forces. The form and regularity of the sheet's disintegration process has influence in the size distribution of the produced drop and in the Sauter mean diameter (SMD). The initial thickness of the produced liquid sheet is important to determine the medium size of obtained drops. It was observed that thicker films produce thicker ligaments and larger drops. The medium drop diameter produced in conical sheets of pressurized swirl atomizers is calculated according to the thickness of the sheets and in the wavelength for the maximum growth tax.
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Holck, David E. E., and Joel Kopelman. "Face-Lifting Techniques." In Surgery of the Eyelid, Lacrimal System, and Orbit. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780195340211.003.0039.
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Facial rhytidectomy is a rejuvenative surgical procedure designed to improve the aging changes in the lower third of the face and neck. It can significantly improve jowling, the jaw line, and the portion of the neck from the hyoid bone to the jaw line (the cervicomental angle). It is less successful at improving the midface or nasolabial folds. Rhytidectomy optimizes the age-appropriate aesthetic but does not stop the normal aging progression after surgery. While a wellperformed rhytidectomy is extremely gratifying for both patient and surgeon, it is elective and invasive, with prolonged rehabilitation and potential morbidity. Complications are poorly tolerated, and therefore pitfalls should be meticulously avoided. Fundamental steps in facial rhytidectomy include incision planning, skin flap dissection, addressing the superficial musculo-aponeurotic system (SMAS) and platysma, liposuction or direct lipectomy, skin redraping, and wound closure. These are standard in lower-third facial and neck rejuvenation. Face lifting is an imperfect procedure: the surgeon takes advantage of camouflaged incisions and healing patterns to obtain optimal rejuvenation. The facial anatomy of the lower third of the face and neck is complex but may be best viewed in a layered approach. Facial skin varies in thickness, with eyelid skin being the thinnest and cheek skin the thickest. The skin of the face is nourished via a dermal plexus, which must be maintained in rhytidectomy surgery. Beneath the skin lies facial subcutaneous fat. This fat is lobulated and enclosed by fibrous septa, which connect the superficial fascia to the dermis. The thickest portion of subcutaneous fat is the malar fat pad, bounded by the infraorbital rim above, the nasolabial fold medially, and the zygomaticus major muscle laterally. Minimal subcutaneous fat is located in the lower eyelid region and in the perioral region. Below the level of the subcutaneous fat is the SMAS. This fibromuscular sheet is continuous with the superficial temporalis fascia and galea cranially and the platysma muscle caudally. The SMAS envelops and connects the superficial mimetic muscles to the dermis, expanding the range of facial expression to the skin via distribution of force.
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Taillant, Jorge Daniel. "The Barrick Veto." In Glaciers. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780199367252.003.0010.
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Buenos Aires, Argentina—October 23, 2008. The team at the Environment Secretariat could not believe the outcome of the congressional vote the previous day, October 22. Argentina had achieved the world’s first national glacier protection law, the Minimum Standards Law for the Protection of Glaciers and the Periglacial Environment. The law was strongly conservationist and excluded all industrial activities on or near glaciers and in the periglacial environment. It declared glaciers a strategic reserve, defined glaciers broadly to protect even small perennial ice patches, and banned mining in glacier and periglacial areas. Some of the more salient text read:. . . Article 1. The present law establishes the minimum standards for the protection of glaciers and the periglacial environment with the objective of preserving them as strategic reserves of hydrological resources and as providers of water recharge for hydrographic basins. Article 2. Definition. To the effects of the present law, glaciers are all perennial stable or slowly flowing ice mass, with or without interstitial water, formed by the recrystallization of snow, located in different ecosystems, no matter what their size, dimension or state of conservation. The rock debris material of each glacier is considered a constituent part of the glacier, as are the internal and superficial water courses. Likewise, the periglacial environment is the area of the high mountain with frozen grounds that acts as a regulator of hydrological resources. Article 6. Prohibited Activities. The following activities are hereby prohibited on glaciers as they could affect their natural condition or the functions cited in Article 1, or as they would imply their destruction, moving, or interference with their movement, in particular: a)The liberation, dispersion or deposit of contaminating substances or elements, chemical products or residue of any nature or volume. The construction of architectural works or infrastructure with the exception of those necessary for scientific research. Mining or hydrocarbon exploration or exploitation. This restriction includes activities in periglacial areas saturated in ice. Emplacement of industries. . . . It took a while for the implications of the law to sink in.
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Epstein, Irving R., and John A. Pojman. "Fundamentals." In An Introduction to Nonlinear Chemical Dynamics. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195096705.003.0007.
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Before plunging into the meat of our discussions, we will review some basic but necessary ideas. Much of this material will be familiar to many readers, and we encourage you to move quickly through it or to skip it completely if appropriate. If you have not encountered these concepts before, you will find it worthwhile to invest some time here and perhaps to take a look at some of the more detailed references that we shall mention. We begin with a review of chemical kinetics. We then consider how to determine the stability of steady states in an open system using analytical and graphical techniques. Finally, we look at some of the methods used to represent data in nonlinear dynamics. The problems that we are interested in involve the rates of chemical reactions, the study of which forms the basis of chemical kinetics. This is a rich and beautiful subject, worthy of whole volumes. For those interested in a less superficial view than we have room to present here, we recommend several excellent texts on kinetics (Jordan, 1979; Cox, 1994; Espenson, 1995). We review here a minimal set of fundamentals necessary for what comes later.
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Liu, Hugo. "Unraveling the Taste Fabric of Social Networks." In Social Networking Communities and E-Dating Services, 18–43. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-104-9.ch002.
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Popular online social networks such as Friendster and MySpace do more than simply reveal the superficial structure of social connectedness — the rich meanings bottled within social network profiles themselves imply deeper patterns of culture and taste. If these latent semantic fabrics of taste could be harvested formally, the resultant resource would afford completely novel ways for representing and reasoning about web users and people in general. This paper narrates the theory and technique of such a feat — the natural language text of 100,000 social network profiles were captured, mapped into a diverse ontology of music, books, films, foods, etc., and machine learning was applied to infer a semantic fabric of taste. Taste fabrics bring us closer to improvisational manipulations of meaning, and afford us at least three semantic functions — the creation of semantically flexible user representations, cross-domain taste-based recommendation, and the computation of taste-similarity between people — whose use cases are demonstrated within the context of three applications — the InterestMap, Ambient Semantics, and IdentityMirror. Finally, we evaluate the quality of the taste fabrics, and distill from this research reusable methodologies and techniques of consequence to the semantic mining and Semantic Web communities.
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Liu, Hugo, Pattie Maes, and Glorianna Davenport. "Unraveling the Taste Fabric of Social Networks." In Selected Readings on the Human Side of Information Technology, 256–82. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-088-2.ch015.
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Popular online social networks such as Friendster and MySpace do more than simply reveal the superficial structure of social connectedness — the rich meanings bottled within social network profiles themselves imply deeper patterns of culture and taste. If these latent semantic fabrics of taste could be harvested formally, the resultant resource would afford completely novel ways for representing and reasoning about web users and people in general. This paper narrates the theory and technique of such a feat — the natural language text of 100,000 social network profiles were captured, mapped into a diverse ontology of music, books, films, foods, etc., and machine learning was applied to infer a semantic fabric of taste. Taste fabrics bring us closer to improvisational manipulations of meaning, and afford us at least three semantic functions — the creation of semantically flexible user representations, crossdomain taste-based recommendation, and the computation of taste-similarity between people — whose use cases are demonstrated within the context of three applications — the InterestMap, Ambient Semantics, and IdentityMirror. Finally, we evaluate the quality of the taste fabrics, and distill from this research reusable methodologies and techniques of consequence to the semantic mining and Semantic Web communities.
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Liu, Hugo, Pattie Maes, and Glorianna Davenport. "Unraveling the Taste Fabric of Social Networks." In Human Computer Interaction, 1521–46. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-87828-991-9.ch096.
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Popular online social networks such as Friendster and MySpace do more than simply reveal the superficial structure of social connectedness—the rich meanings bottled within social network profiles themselves imply deeper patterns of culture and taste. If these latent semantic fabrics of taste could be harvested formally, the resultant resource would afford completely novel ways for representing and reasoning about web users and people in general. This paper narrates the theory and technique of such a feat—the natural language text of 100,000 social network profiles were captured, mapped into a diverse ontology of music, books, films, foods, etc., and machine learning was applied to infer a semantic fabric of taste. Taste fabrics bring us closer to improvisational manipulations of meaning, and afford us at least three semantic functions—the creation of semantically flexible user representations, cross-domain taste-based recommendation, and the computation of taste-similarity between people— whose use cases are demonstrated within the context of three applications—the InterestMap, Ambient Semantics, and IdentityMirror. Finally, we evaluate the quality of the taste fabrics, and distill from this research reusable methodologies and techniques of consequence to the semantic mining and Semantic Web communities.
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Konomi, T., N. Suzuki, K. Kono, and T. Asazuma. "Surgical results of Hybrid Mita method to idiopathic scoliosis: minimum two years follow-up." In Studies in Health Technology and Informatics. IOS Press, 2021. http://dx.doi.org/10.3233/shti210469.
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Hybrid Mita (Suzuki) method is a newly developed technique of scoliosis surgery. This concept consists of three components: rib mobilization, rod rotation maneuver and hook rotation maneuver, which does not require intra-operative CT scan with lower risk of screw malposition. The aim of this study is to evaluate the efficacies of this method for correction in scoliosis. : This is a retrospective observational study, consist of eighty-nine idiopathic scoliosis patients who underwent this method between 2009 and 2016 with minimum 2-years follow-up. The curve pattern, Cobb angle, hump height and angle, peri-operative events and complications were analyzed. The mean pre- and post-operative Cobb angle was 50.9° and 10.1°, respectively. The average correction rate was 80.5%. Hump height was reduced from 20.2 mm to 9.8 mm and hump angle reduced from 13.1° to 6.1° in average. The correction loss at the final follow-up was 0.3° in average. There were two local superficial infection cases, but there was no instrumentation failure such as malposition or dislodgement, or pseudarthrosis. This novel method is promising to provide excellent clinical correction to idiopathic scoliosis, which is no less than all pedicle screw constructs. The technique of the skillful utilization of hooks in spinal surgery should not perish from the stage.
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Toniazzo, V., C. Mustin, R. Benoit, B. Humbert, and J. Berthelin. "Superficial compounds produced by Fe(III) mineral oxidation as essential reactants for bio-oxidation of pyrite by Thiobacillus ferrooxidans." In Biohydrometallurgy and the Environment Toward the Mining of the 21st Century - Proceedings of the International Biohydrometallurgy Symposium, 177–86. Elsevier, 1999. http://dx.doi.org/10.1016/s1572-4409(99)80017-0.
Full textConference papers on the topic "Superficie minima"
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Engineer, Ravi S., and Hemant B. Mehta. "Experimental Study on Two-Phase Pressure Drop of Air-Water in Horizontal Mini Channel." In ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icnmm2014-22211.
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The new correlation for two-phase pressure drop for mini channel is developed by performing experiment on adiabatic two-phase pressure drop in mini channel with 3.1 mm diameter. Air-water mixture is used as the working substance. 180°-90°-90° (straight flow) test sections made of transparent glass tubes of 3.1 mm diameter with lengths of 900 mm. The superficial velocity varies from 0.2238 m/s to 1.1876 m/s for liquid (UL) and air (UG). Two phase flow pressure drop experiment is divided into two parts. First single phase pressure drop for air and water is experimented. The diameter is verified by measuring pressure drop of the air. Single phase pressure drop for air and water is experimented first which is followed by two phase pressure drop in the same mini channel. The existing correlations for macro and mini-channels are compared with the experimental data. Using Matlab & Minitab; a new correlation has been developed to predict two-phase pressure drop in horizontal mini channels.
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Kebriaee, M. H., H. Karabi, S. Khorsandi, and M. H. Saidi. "Two Phase Gas-Liquid Bubbly Flow Modeling in Vertical Mini Pipe." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22758.
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Studies on two-phase flow in small scale pipes have become more important, because of the application of mini-scale devices in several engineering fields including, high heat-flux compact heat exchangers, and cooling systems of various types of equipment. In a mini pipe the behavior of two phase flow is not the same as flow in conventional pipes. The difference is caused by different effective forces; for e. g. inside a mini pipe capillary forces are more important in comparison with gravitational forces. This paper is devoted to numerical simulation of gas-liquid two phase flow in a vertical mini pipe. Prediction of bubble shape and the effects of gas and liquid velocities on flow characteristics are considered. Also simulation involves prediction of changes in average void fraction along pipe axis. Numerical simulations in this paper are performed by a designed and developed CFD package which is based on Eulerian-Eulerian approach. The governing equations which are solved in the CFD package are momentum, continuity and Fractional Volume of Fluid (VOF) function equations. The fluid is assumed to be viscous and incompressible. The pressure-velocity coupling is obtained using the SIMPLEC algorithm. The geometry, which have been studied in this paper, is a D = 1.02 mm pipe, with 500 mm height. Bubble shape and the distribution of void fraction in a mini pipe are related to many parameters such as: gas and liquid velocities, pressure losses and etc. Since these mechanisms vary over time, time-average value of void fraction is used. Comparisons between Numerical results and experimental work which performed by hibiki et al. [1] indicated good agreement. Also results have shown that the present model is capable to simulate the behavior of nitrogen-water two phase flow in a mini pipe with acceptable accuracy. Furthermore, the results indicates that average void fraction along the pipe axis is related to the height and nitrogen superficial velocity. Also it is observed that at constant nitrogen superficial velocities, average void fraction decreases with water superficial velocity increments.
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Pylypenko, Anton, Yevgenii Rastigejev, Lijun Wang, and Abolghasem Shahbazi. "Experimental and Numerical Study of Cold Gas-Solid Flow Regimes in a Fluidized Bed Gasifier." In ASME 2017 Power Conference Joint With ICOPE-17 collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/power-icope2017-3263.
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The objective of this work is to analyze the dynamics and regimes of cold gas-solid flow in a biomass gasifier that is built at North Carolina Agricultural and Technical State University and to identify its corresponding ranges of operating conditions. The value of the minimum fluidization velocity Umf ≈ 8 cm/s has been found experimentally in a series of measurements of a pressure drop in the fluidized bed filled with Gledart type-B silica sand for the range of superficial gas velocities between 0 and 40 cm/s. To complement the experimental results, a set of three-dimensional numerical simulations of the isothermal gas-solid flow based on Eulerian-Eulerian approach has been performed. The analysis of the fluidization characteristics such as axial void fraction distributions has allowed us to evaluate the dependence of the bed expansion ratios from the flow superficial velocity. Good agreement between experimental and numerical results for the considered operating conditions of the gasifier has been observed.
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Watanabe, Shunichi, Yutaka Fukuhara, Tatsuya Hazuku, Tomoji Takamasa, and Takashi Hibiki. "Effect of Gravity on Phase Distribution Patterns of Bubbly Two-Phase Flow in a Vertical Mini Pipe." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-29636.
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In relation to the development of the interfacial area transport equation, a precise database of the axial development of void fraction profile, interfacial area concentration and Sauter mean bubble diameter in an adiabatic nitrogen-water bubbly flow in a 5 mm-diameter mini pipe was constructed for normal and microgravity conditions using stereo image-processing. The flow measurements were performed at four axial locations (axial distance from the inlet normalized by the pipe diameter, z/D = 5.5, 34, 72 and 110) and with various flows: superficial gas velocity of 0.00434–0.0420 m/s, and superficial liquid velocity of 0.239–0.949 m/s. The effect of gravity on radial distribution of bubbles and the axial development of two-phase flow parameters is discussed in detail based on the obtained database and visual observation.
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Ohtake, Hiroyasu, Hideyasu Ohtaki, and Yasuo Koizumi. "Flow Characteristics and Frictional Pressure Drops of Gas-Liquid Two-Phase Flow in Mini-Micro Pipes and at Vena Contract and Expansion." In ASME 2007 5th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2007. http://dx.doi.org/10.1115/icnmm2007-30198.
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The frictional pressure drops and two-phase flow patterns of gas-liquid two-phase flow in mini-micro pipes and at vena contract and expansion were investigated experimentally. Test liquid was water; test gas was argon. The diameter of the test mini-pipe was 0.5, 0.25 and 0.12 mm, respectively. The pressure drop data and the flow pattern were collected over 2.1 < Ug < 92.5 m/s for the superficial gas velocity and 0.03 < Ul < 10 m/s for the superficial liquid velocity. The experimental results show that the flow patterns were slug, churn, ring and annular flows; pure bubbly flow pattern was not observed in a range of the present experimental conditions. The two-phase friction multiplier data for D > 0.5 mm showed to be in good agreement with the conventional correlations. On the other hand, the two-phase friction multiplier data for D < 0.25 mm differed from the calculated values by the conventional correlations. Then, thickness of liquid film around a gas plug and size of gas core were estimated and the effect of frictional pressure drop on channel size was discussed through Knudsen Number of gas and instability on liquid-gas interface. The coefficients of sudden enlargement and sudden contraction in mini-pipes for the gas-water two-phase flow were modified from the present experimental results.
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Lee, Chi Young, and Sang Yong Lee. "Pressure Drop of Two-Phase Dry-Plug Flow in Round Mini-Channels." In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62292.
Full textAbstract:
As the fluid devices are being miniaturized, the flow channels inside the devices also become smaller, often down to about the size of 1 mm in hydraulic diameter. In such mini-channels, the interfacial tensions between solid and liquid (σSL) and solid and gas (σSG), as well as the surface tension between liquid and gas (σLG), play an important role in two-phase flows, which are determined by choice of tube materials. Among the various two-phase flow regimes, the plug flow appears more frequently in mini-channels than in macro-channels. The surface wettability affected the morphologies of two-phase plug flows, and eventually resulted in large difference in pressure drop. In the present experimental study, contribution of the moving contact lines to the pressure drop of air-water dry-plug flow (dry wall condition at the gas portions) in round mini-channels was investigated. The polyurethane and Teflon tubes were tested; the tube diameters were 2.16 and 1.62 mm, and the contact angles were about 75 and 110°, respectively. All the experiments were performed only in the dry-plug flow regime. The pressure drop became larger either by increasing the liquid superficial velocity or by decreasing the gas superficial velocity due to the increase of the number of the moving contact lines. It implies that the pressure drop by the energy dissipation of moving contact line is an important parameter to be considered in predicting the pressure drop in the dry-plug flow regime. Therefore, the total pressure drop of two-phase dry-plug flows consists of three parts: The frictional pressure drops at the gas- and liquid-plug portions and the pressure drop by energy dissipation at the moving contact lines. The void fraction and the number of liquid plugs could be determined from the superficial velocities of gas and liquid once the two-phase mixer is fixed. Also, the pressure drop by the energy dissipation at the moving contact lines was predicted through modification of the dynamic contact angle analysis. Finally, the simple model was proposed to predict the pressure drop of two-phase dry-plug flow in round mini-channels, which represents the experimental data within the mean deviation of 5.3%.
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Ohtake, Hiroyasu, Hideyasu Ohtaki, Masato Hagiwara, and Yasuo Koizumi. "Experimental and Analytical Studies on Frictional Pressure Drops of Gas-Liquid Two-Phase Flow in Mini-Micro Pipes and at Vena Contract and Expansion." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-44006.
Full textAbstract:
The frictional pressure drops of gas-liquid two-phase flow in mini-micro pipes and at vena contract and expansion were investigated experimentally and analytically. Pressure drops of straight pipe, sudden enlargement and sudden contraction of gas-liquid two-phase flow in mini-pipes were measured. Test liquid was water at room temperature; test gas was argon. The diameter of the test mini-pipe was 0.5, 0.25 and 0.12 mm, respectively; the length was 500, 250 and 50 mm, respectively. The cross-sectional ratio of the contraction was about 1000; the ratio of the enlargement was about 0.001. The pressure drop data and the flow pattern were collected over 3.0 < UG < 130 m/s for the superficial gas velocity and 0.02 < UL < 6.0 m/s for the superficial liquid velocity. The two-phase friction multiplier data for D > 0.5 mm showed to be in good agreement with the conventional correlations. On the other hand, the two-phase friction multiplier data for D < 0.25 mm differed from the calculated values by the conventional correlations. Then, thickness of liquid film around a gas plug and size of gas core were estimated and the effect of frictional pressure drop on channel size was discussed through Knudsen Number of gas and instability on liquid-gas interface. Namely, the effect of mini-pipe was rarefaction effects, Kn<0.1. New correlation of frictional pressure drop of gas-liquid two-phase flow is proposed for mini pipes. The coefficients of sudden enlargement and sudden contraction in mini-pipes for the gas-water two-phase flow were modified from the present experimental results. The experimental results were also examined through numerical simulation by a commercial code.
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Miyazaki, Takeru, Misaki Baba, Hideki Murakawa, Hitoshi Asano, Katsumi Sugimoto, and Daisuke Ito. "Two-Phase Flow Behavior and Heat Transfer Characteristics in Kettle Reboiler." In ASME 2017 Power Conference Joint With ICOPE-17 collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/power-icope2017-3293.
Full textAbstract:
Effects of the tube array, such as in-line and staggered, on void-fraction distribution and heat transfer coefficient around a tube were experimentally investigated. The test section was vertical duct with inner size of 90 × 90 mm2. Diameter of the tubes was 15 mm, and the pitch-to-diameter ratio was 1.5 for both tube bundles. Working fluids were air and water. Experiments were carried out at superficial gas velocity defined at minimum area section, Jg, of 0.10 to 0.89 m/s, superficial liquid velocity, Jl, of 0.1 to 0.3 m/s, under the atmospheric condition. Measurements of void-fraction distribution were carried out using X-ray radiography. In addition, heat transfer coefficient around a tube was measured and the heat transfer coefficients in association with the flow regime and the void-fraction distribution were evaluated. Time-average void-fraction was higher around upstream of a tube than that of downstream at bubbly flow condition for both bundles. Under intermittent flow condition, time-average void fraction at the maximum gap were higher than that around the other points in both tube bundles. For in-line tube bundle, enhancement of the heat transfer clearly appeared between ±90 to 180°. For staggered tube bundle, the heat transfer increased all over the pipe.
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Ohtake, Hiroyasu, Masato Hagiwarai, and Yasuo Koizumi. "Experimental and Analytical Studies on Frictional Pressure Drops of Gas-Liquid Two-Phase Flow at Vena Contract and Expansion." In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62363.
Full textAbstract:
The frictional pressure drops of gas-liquid two-phase flow in mini-micro pipes and at vena contract and expansion were investigated experimentally and analytically. Pressure drops of straight pipe, sudden enlargement and sudden contraction of gas-liquid two-phase flow in mini-pipes were measured. Test liquid was water at room temperature; test gas was argon. The diameter of the test mini-pipe was 1.0 and 0.5 mm, respectively. Each test tube was connected at both ends to small tanks. The diameter of the small tank was 15 mm for 1.0 mm diameter of test tube and 5 mm for 0.5 mm diameter of test tube, respectively. Thus, the cross-sectional ratio of the contraction was about 1000; the ratio of the enlargement was about 0.001. The pressure drop data were collected over 3.0 < UG < 130 m/s for the superficial gas velocity and 0.02 < UL < 6.0 m/s for the superficial liquid velocity. The present experimental results of sudden contraction pressure loss factor Kc and sudden enlargement pressure loss factor Ke of single-phase liquid flow in mini-pipes differed from the conventional values, Kc = 0.5 and Ke = 1.0. The calculated results by using a commercial code, STAR-CD, agreed with the present experimental results for mini-pipes. Assuming to homogenous flow and incompressible flow, sudden contraction pressure loss, sudden enlargement pressure loss and their factors Kc, Ke for gas-liquid two-phase flow were estimated by using momentum equation and energy equation. The contraction pressure losses by Hewitt’s correlation for conventional pipes were similar to the present experimental results of the contraction for mini-circular pipe. Collier’s correlation of the enlargement pressure loss for conventional pipes underpredicted the present experimental results of the enlargement for mini-tube. Based on the present experimental results, new correlations were obtained for the enlargement and the contraction pressure losses in mini-channel.
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Xiong, Renqiang, and J. N. Chung. "Adiabatic Gas-Liquid Two-Phase Flow Patterns in Microchannels." In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98476.
Full textAbstract:
Flow patterns of adiabatic gas-liquid two-phase flow in micro-channels were experimentally investigated. Using nitrogen and water, experiments were conducted in square micro-channels with hydraulic diameters of 0.209mm, 0.412mm and 0.622 mm, respectively. Gas and liquid superficial velocities were varied from 0.06–72.3 m/s and 0.02–7.13 m/s, respectively. Four defined flow patterns, bubbly-slug flow, slug-ring flow, dispersed-churn flow and annular flow, were observed in micro-channels of 0.412 mm and, 0.622 mm. In the micro-channel of 0.209 mm, the bubbly-slug flow became the slug-flow and the dispersed-churn flow disappeared due to the surface tension effect and the smooth gas-liquid interface. The flow regime maps for the current three micro-channels were constructed and showed the transition lines shifted to higher gas superficial velocity due to the stronger surface tension effect with a smaller channel size in micro-channels. They were also compared with some other micro-channel flow regime maps and the mini-channel flow regime map based on the Weber number model, which showed the flow map for the micro-channel is significantly sensitive to the working fluid, channel geometry and channel size and the flow regime criteria developed for mini-channels should not be applied for micro-channels without further verification.