Academic literature on the topic 'Conduit geometry'
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Journal articles on the topic "Conduit geometry":
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Kozono, Tomofumi, Hidemi Ishibashi, Satoshi Okumura, and Takahiro Miwa. "Conduit Flow Dynamics During the 1986 Sub-Plinian Eruption at Izu-Oshima Volcano." Journal of Disaster Research 17, no. 5 (August 1, 2022): 754–67. http://dx.doi.org/10.20965/jdr.2022.p0754.
Abstract:
We investigated conduit flow dynamics during the 1986 sub-Plinian eruption of Izu-Oshima volcano, Japan, using a 1-D steady conduit flow model. Following observations that the magma plumbing system beneath Izu-Oshima, characterized by the feeding of a dyke, generated a fissure-type sub-Plinian eruption, we considered a dyke-like conduit geometry by applying a pseudo-dyke conduit with an ellipsoidal horizontal cross-section. Under appropriate parameter settings constrained by geological, petrological, and geophysical observations, we identified a conduit geometry that enables steady solutions of a conduit flow that generates the sub-Plinian eruption. A dyke-like conduit geometry allows us to widen the range of geometric parameters of the solution. We found that the distribution of magma overpressure in the conduit strongly depends on conduit geometry. When the conduit geometry is composed of deeper and shallower dykes with large and small aspect ratios, respectively, localized overpressurization occurs in the region before magma fragmentation. This overpressurization in the dyke-like conduit may induce a characteristic crustal deformation similar to that caused by a vertical tensile fault. It is crucial to consider the effects of conduit flow with a dyke-like geometry on deformation for precise monitoring of eruption sequences based on geodetic signals in future eruptions at Izu-Oshima volcano.
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Shimizu, Yukimaru, Yoshiki Futaki, and C. Samuel Martin. "Secondary Flow and Hydraulic Losses Within Sinuous Conduits of Rectangular Cross Section." Journal of Fluids Engineering 114, no. 4 (December 1, 1992): 593–600. http://dx.doi.org/10.1115/1.2910072.
Abstract:
This paper describes the relationship between hydraulic losses and secondary flow within sinuous conduits with complicated bends. It has been found that the nature of secondary flow present in the bends is quite sensitive to the geometric configuration of the bend and the actual aspect ratio of the conduit section. Indeed, many different secondary flow patterns have been found to exist as the bend geometry is altered. A wide range of experiments has been conducted for various aspect ratios of a rectangular conduit with different curvatures.
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Ostad, Hadi, Zargham Mohammadi, and Francesco Fiorillo. "Assessing the Effect of Conduit Pattern and Type of Recharge on the Karst Spring Hydrograph: A Synthetic Modeling Approach." Water 15, no. 8 (April 19, 2023): 1594. http://dx.doi.org/10.3390/w15081594.
Abstract:
It is widely accepted that spring hydrographs are an effective tool for evaluating the internal structure of karst aquifers because they depict the response of the whole aquifer to recharge events. The spring hydrograph is affected by various factors such as flow regime, geometry, type of recharge, and hydraulic properties of conduit. However, the effect of conduit network geometry received less attention and required more comprehensive research studies. The present study attempted to highlight the impact of the two most frequent patterns of karst conduits (i.e., branchwork and network maze) on the characteristic of the spring hydrograph. Therefore, two conduit patterns, branchwork and network maze, were randomly generated with MATLAB codes. Then, MODFLOW-CFP was used to quantify the effect of conduit pattern, conduit density, and diffuse or concentrated recharge on the spring hydrograph. Results reveal that peak discharge, fast-flow recession coefficient, and the return time to baseflow are mainly affected by conduit network pattern, conduit network density, and recharge, respectively. In contrast, the time to reach peak flow only reacts to recharge conditions. Large variations in conduit density produce tangible changes in the baseflow recession coefficient.
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Fountain, Andrew G., Robert B. Schlichting, Peter Jansson, and Robert W. Jacobel. "Observations of englacial water passages:a fracture-dominated system." Annals of Glaciology 40 (2005): 25–30. http://dx.doi.org/10.3189/172756405781813762.
Abstract:
AbstractTo test models of the hydraulics and geometry of englacial conduits, 48 holes (3900m of ice) were drilled into Storglaciaren, Sweden, in search of conduits. About 79% of the holes intersected a hydraulically connected englacial feature. A video camera was used to examine the features and measure local water-flow rates. Because of the extremely clear ice that surrounded most features, their geometry could not be discerned. Of the remaining features, 80% (36) were fracture-like, 16%(6) were of complex geometry, and 4%(2) exhibited a conduit-like geometry. The fracture-like features exhibited steep plunges (∼70˚), narrow openings (∼40mm) and slow water-flow speeds (∼10mms–1). We argue that these fracture-like features are indeed englacial fractures of unknown origin. The depth to fractures intersection varied from near the glacier surface to 96% of local ice depth, with a maximum depth of 131 m. Few hydraulically connected fractures exhibited water motion, indicating some preferential flow pathways exist. We found one ‘traditional’ englacial conduit after an intentional search in a field of moulins. These results suggest that englacial water flow is conveyed through a ubiquitous network of fractures and that conduits are relatively rare.
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Gunn, John, and Chris Bradley. "Characterising Rhythmic and Episodic Pulsing Behaviour in the Castleton Karst, Derbyshire (UK), Using High Resolution in-Cave Monitoring." Water 15, no. 12 (June 20, 2023): 2301. http://dx.doi.org/10.3390/w15122301.
Abstract:
The discharge from most karst springs exhibits a consistent and reasonably predictable response to recharge but a few exhibit short-term (‘rhythmic’) changes in flow that are commonly attributed to the geometry of feeder conduits and the action of siphons. This paper investigates water flow in a karst system that exhibits rhythmic and episodic changes in discharge due to variations in flow from two phreatic conduits (Main Rising (MR) and Whirlpool Rising (WR)) that pass through Speedwell Cavern en route to the springs. Water tracing experiments indicate that the conduits receive both allogenic and autogenic recharge. Flow dynamics and conduit behaviour were investigated using high-resolution (2-min) water depth data collected from MR and WR between 2012 and 2015 (when MR was dominant) and between 2021 and 2023 (when WR was dominant). Water depths were also logged in a cave at the upstream end of a conduit draining to both MR and WR and at springs. The short-term temporal variability in water depths at both MR and WR is greater than any documented in previous studies. This is attributed to conduit bedrock geometry and changes in conduit permeability due to sediment accumulation in phreatic loops, which together influence the response to recharge.
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Imqam, Abdulmohsin, Ze Wang, and Baojun Bai. "Preformed-Particle-Gel Transport Through Heterogeneous Void-Space Conduits." SPE Journal 22, no. 05 (March 22, 2017): 1437–47. http://dx.doi.org/10.2118/179705-pa.
Abstract:
Summary Preformed particle gels (PPGs) have been successfully applied as a plugging agent to solve the conformance problem in fractured reservoirs. They are injected to plug fractures and then divert displacing fluid into poorly swept zones/areas. However, PPG-propagation and -plugging mechanisms through open void-space conduits (VSCs) have not been studied thoroughly. This paper investigated various situations involving heterogeneous conduits and their geometrical effect on PPG injectivity. Five-foot tubes were used to mimic VSCs. Three models were designed to gain understanding on how conduit geometry and PPG properties affect gel transportation, including a single conduit with a uniform internal diameter (ID); a single conduit with a nonuniform ID along its length; and two parallel conduits with different ID ratios with respect to each other. Results obtained from single-conduit models with uniform and nonuniform diameters showed PPG-injection pressure increased significantly as the conduit became more heterogeneous. Particle gels accumulated at the choke point within each conduit and caused injection pressure to increase accordingly. When two parallel conduits are available for flow, the relative distance of PPG penetration into the conduits depends strongly on the ratio of the conduit diameters and the gel strength. In addition, the ratio of gel-particle-size diameter to conduit diameter contributes significantly to the gel-transport selection. This paper demonstrates important impact elements of gel propagation for different heterogeneous-conduit situations.
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Tsamis, Alkiviadis, Alexander Rachev, and Nikos Stergiopulos. "A constituent-based model of age-related changes in conduit arteries." American Journal of Physiology-Heart and Circulatory Physiology 301, no. 4 (October 2011): H1286—H1301. http://dx.doi.org/10.1152/ajpheart.00570.2010.
Abstract:
In the present report, a constituent-based theoretical model of age-related changes in geometry and mechanical properties of conduit arteries is proposed. The model was based on the premise that given the time course of the load on an artery and the accumulation of advanced glycation end-products in the arterial tissue, the initial geometric dimensions and properties of the arterial tissue can be predicted by a solution of a boundary value problem for the governing equations that follow from finite elasticity, structure-based constitutive modeling within the constrained mixture theory, continuum damage theory, and global growth approach for stress-induced structure-based remodeling. An illustrative example of the age-related changes in geometry, structure, composition, and mechanical properties of a human thoracic aorta is considered. Model predictions were in good qualitative agreement with available experimental data in the literature. Limitations and perspectives for refining the model are discussed.
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Rabah, Amal, Manuel Marcoux, and David Labat. "Effects of Geometry on Artificial Tracer Dispersion in Synthetic Karst Conduit Networks." Water 15, no. 22 (November 7, 2023): 3885. http://dx.doi.org/10.3390/w15223885.
Abstract:
This paper presents the modeling results of tracer test simulations performed using COMSOL Multiphysics (version 6.1), a powerful software for multiphysics simulation. The simulations consist of the propagation of artificial tracers injected into different model configurations. This study is based on computational fluid dynamics (CFDs), which allows us to take into consideration the turbulent regime of the water flow in conduits. The objective of this contribution is to identify the relationship between the tracer dynamics and the geometric parameters of synthetic karstic systems via a systematic investigation of the occurrence of dual-peaked breakthrough curves (BTCs) in tracer tests. Various conduit structures were proposed by modifying five key factors: conduit diameter, presence of pools, connection angle between conduits, distance of the outlet from the inlet, and number of branches. The next step will be to confront these computational experiments with real-world tracer test experiments.
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KAMINTZIS, J. E., J. P. P. JONES, T. D. L. IRVINE-FYNN, T. O. HOLT, P. BUNTING, S. J. A. JENNINGS, P. R. PORTER, and B. HUBBARD. "Assessing the applicability of terrestrial laser scanning for mapping englacial conduits." Journal of Glaciology 64, no. 243 (December 20, 2017): 37–48. http://dx.doi.org/10.1017/jog.2017.81.
Abstract:
ABSTRACTThe morphology of englacial drainage networks and their temporal evolution are poorly characterised, particularly within cold ice masses. At present, direct observations of englacial channels are restricted in both spatial and temporal resolution. Through novel use of a terrestrial laser scanning (TLS) system, the interior geometry of an englacial channel in Austre Brøggerbreen, Svalbard, was reconstructed and mapped. Twenty-eight laser scan surveys were conducted in March 2016, capturing the glacier surface around a moulin entrance and the uppermost 122 m reach of the adjoining conduit. The resulting point clouds provide detailed 3-D visualisation of the channel with point accuracy of 6.54 mm, despite low (<60%) overall laser returns as a result of the physical and optical properties of the clean ice, snow, hoar frost and sediment surfaces forming the conduit interior. These point clouds are used to map the conduit morphology, enabling extraction of millimetre-to-centimetre scale geometric measurements. The conduit meanders at a depth of 48 m, with a sinuosity of 2.7, exhibiting teardrop shaped cross-section morphology. This improvement upon traditional surveying techniques demonstrates the potential of TLS as an investigative tool to elucidate the nature of glacier hydrological networks, through reconstruction of channel geometry and wall composition.
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Schuler, Thomas, and Urs H. Fischer. "Elucidating changes in the degree of tracer dispersion in a subglacial channel." Annals of Glaciology 37 (2003): 275–80. http://dx.doi.org/10.3189/172756403781815915.
Abstract:
AbstractTracer injections into a subglacial channel at Unteraargletscher, Switzerland, were repeated at intervals of about 2 hours over two diurnal discharge cycles in August and September 2000. Records of dye concentration reveal a pronounced hysteresis in the velocity–dispersion relationship, thereby indicating alterations in the drainage system. Theoretical considerations for Röthlisberger channels suggest an evolution of the conduit cross-section in response to a diurnally varying discharge. We studied the relation between conduit cross-section and tracer dispersion with numerical tracer experiments. The velocity field for steady flow through a given conduit geometry is calculated using a commercial flow solver. Tracer transport is represented by a scalar volume which is advected by the velocity field. Experiments were conducted for several scenarios by varying flow velocity, conduit geometry and conduit roughness. Results show only a weak dependence of dispersion on conduit size. In contrast, changes in roughness of the conduit walls reveal a strong effect on tracer dispersion. Therefore, to explain the observed hysteresis in the velocity–dispersion relationship, we suggest that the evolution of a subglacial flow path might involve changes in roughness.
Dissertations / Theses on the topic "Conduit geometry":
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Douros, Ioannis. "Towards a 3 dimensional dynamic generic speaker model to study geometry simplifications of the vocal tract using magnetic resonance imaging data." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0115.
Abstract:
Dans cette thèse, nous avons utilisé les données de l’IRM du conduit vocal pour étudier la production de la parole. La première partie consiste en l’étude de l’impact que le vélum, l’épiglotte et la position de la tête a sur la phonation de cinq voyelles françaises. Des simulations acoustiques ont été utilisées pour comparer les formants des cas étudiés avec la référence afin de mesurer leur impact. Pour cette partie du travail, nous avons utilisé des IRM statiques en 3D. Comme la parole est généralement une phénomène dynamique une question s’est posée, à savoir s’il serait possible de traiter les données 3D afin d’incorporer des informations temporelles de la parole continue. Par conséquent, la deuxième partie présente quelques algorithmes que l’on peut utiliser pour améliorer les données de production de la parole. Plusieurs transformations d’images ont été combinées afin de générer des estimations des formes du conduit vocal qui sont plus informatives que les originales. À ce stade, nous avons envisagé, outre l’amélioration des données de production de la parole, de créer un modèle de référence générique qui pourrait fournir des informations améliorées non pas pour un sujet spécifique, mais globalement pour la parole. C’est pourquoi nous avons consacré la troisième partie l’étude d’un algorithme permettant de créer un atlas spatio-temporel de l’appareil vocal qui peut être utilisé comme référence ou standard pour l’étude de la parole car il est indépendant du locuteur. Enfin, la dernière partie de la thèse, fait référence à une sélection de questions ouvertes du domaine qui restent encore sans réponse, quelques pistes intéressantes que l’on peut développer à partir de cette thèse et quelques approches potentielles qui pourraient être envisager afin de répondre à ces questionsIn this thesis we used MRI (Magnetic Resonance Imaging) data of the vocal tract to study speech production. The first part consist of the study of the impact that the velum, the epiglottis and the head position has on the phonation of five french vowels. Acoustic simulations were used to compare the formants of the studied cases with the reference in order to measure their impact. For this part of the work, we used 3D static MR (Magnetic Resonance) images. As speech is usually a dynamic phenomenon, a question arose, whether it would be possible to process the 3D data in order to incorporate dynamic information of continuous speech. Therefore the second part presents some algorithms that one can use in order to enhance speech production data. Several image transformations were combined in order to generate estimations of vocal tract shapes which are more informative than the original ones. At this point, we envisaged apart from enhancing speech production data, to create a generic speaker model that could provide enhanced information not for a specific subject, but globally for speech. As a result, we devoted the third part in the investigation of an algorithm that one can use to create a spatiotemporal atlas of the vocal tract which can be used as a reference or standard speaker for speech studies as it is speaker independent. Finally, the last part of the thesis, refers to a selection of open questions of the field that are still left unanswered, some interesting directions that one can expand this thesis and some potential approaches that could help someone move forward towards these directions
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Frantz, Yves. "Simulation stochastique des réseaux karstiques." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0215.
Abstract:
Difficiles d'accès, les réseaux karstiques ne sont généralement que partiellement décrits. Les techniques d'exploration classiques produisent par ailleurs des données éparses et sujettes à des incertitudes concernant la position des conduits et leurs dimensions, paramètres essentiels aux simulations d'écoulement. Les simulations stochastiques permettent de mieux gérer et évaluer ces incertitudes en proposant plusieurs représentations équiprobables de systèmes karstiques. Le simulateur idéal devrait permettre de construire des réseaux de drains karstiques tridimensionnels, honorant les observations de terrain (indices de karstification), les connaissances apportées par les essais de traçage, les informations recueillies sur des parties accessibles du réseau et celles apportées par l'étude d'autres réseaux. C'est dans ce contexte que s'inscrit cette thèse qui propose 3 principales contributions. La première contribution est l'analyse statistique d'une base de données de 49 réseaux karstiques. Elle se focalise sur l'étude de la géométrie des conduits, à travers l'analyse de deux métriques : le rayon équivalent et le ratio largeur-hauteur. Aucune loi statistique générique qui décrirait la géométrie des conduits n'a pu être mise en évidence. Néanmoins, la variabilité spatiale des propriétés géométriques à différentes échelles a été caractérisée, notamment grâce au développement de variogrammes 1D-curvilinéaires. L'hypothèse répandue d'une organisation hiérarchique des géométries de conduits a également été analysée et rejetée. La deuxième contribution est le développement de deux méthodes de simulation stochastique de propriétés le long de réseaux karstiques s'appuyant sur les résultats de l'analyse statistique. La première méthode se focalise sur la reproduction de la variabilité des propriétés à l'échelle du réseau, tandis que la deuxième se concentre sur la reproduction de la variabilité au sein et entre les branches du réseau.Elles sont toutes deux basées sur les méthodes de Simulations Gaussiennes Séquentielles (SGS), ici adaptées à des objets 1D-curvilinéaires. La troisième contribution est le prototype d'une méthode ayant pour but de simuler stochastiquement des réseaux karstiques discrets sous forme de graphes (qualifiés de squelettes des réseaux). Il est espéré qu'une fois entièrement développée, elle permette de simuler différents types de réseaux et de prendre directement en compte les données de terrain ainsi que les informations géologiques. Elle consiste en trois grandes étapes : i) la génération d'un nuage de points, ii) le calcul de leur connectivité et iii) leur connexion pour former le squelette du réseau karstique. Ces contributions ouvrent de nouvelles perspectives quant à la simulation de réseaux de drains karstiques utilisables pour la simulation d'écoulement (e.g., SWMM, Epanet, Modflow-CFP), ce qui devrait permettre une meilleure caractérisation des flux en leur seinDespite intensive explorations by speleologists, karstic networks remain only partially described as many conduits are not accessible to humans. The classical exploration techniques produce sparse data subject to uncertainties concerning the conduit position and their dimensions, which are essential parameters for flow simulations.Stochastic simulations make it possible to better handle and assess these uncertainties by offering several equally probable karstic system representations.The ideal simulator should allow for the construction of tridimensional karstic drain networks, respecting the field observations (karstification markers), the knowledge brought by tracer tests, the information collected in the accessible parts of the network and those obtained by the study of other networks.In this context, this PhD thesis offers 3 main contributions.The first contribution is the statistical analysis of a database of 49 karstic networks.It focuses on the study of conduit geometry, through the analysis of two metrics : the equivalent radius and the width-height ratio.No generic statistical law describing the network geometry was found.Nonetheless, the spatial variability of the geometrical properties at different scales was characterized, mostly through the development of 1D-curvilinear variograms.The widespread hypothesis of a hierarchical organization of the conduit geometries has also been analysed and rejected.The second contribution is the development of two methods allowing stochastic simulations of properties along karstic networks and based on the results of the statistical analysis. The first method focuses on the reproduction of the property variability at the network scale, while the second one focuses on the reproduction of the variability within and between the network branches.Both are based on the Sequential Gaussian Simulation methods and are adapted to 1D-curvilinear objects.The third contribution is the prototype of a method aiming to stochastically simulate discrete karstic networks as graphs (known as network skeletons}). We hope that once completed, it would allow the simulation of different network types, while taking directly into account field data and geological information. It is divided in three main steps : i) the generation of a point cloud, ii) the computation of the point connectivity and iii) their connection to create the skeleton of the karstic network.These contributions open new prospects regarding the simulation of karstic drain networks usable for flow simulation (e.g., SWMM, Epanet, Modflow-CFP), which should allow a better characterization of the associated flows
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Díez, Mikel. "Studies of the Mechanics and Structure of Shallow Magmatic Plumbing Systems." Scholar Commons, 2008. https://scholarcommons.usf.edu/etd/214.
Abstract:
Volcanic activity, and the resultant deposits and structures at the Earth's surface, are the outcome of the inner workings of underground magmatic plumbing systems. These systems, essentially, consist of magma reservoirs which supply magma to the surface through volcanic conduits feeding volcanic eruptions. The mechanics and structure of plumbing systems remain largely unknown due to the obvious challenges involved in inferring volcanic processes occurring underground from observations at the surface. Nevertheless, volcanologists are beginning to gain a deeper understanding of the workings and architecture of magmatic plumbing systems from geophysical observations on active volcanoes, as well as from geological studies of the erosional remnants of ancient volcanic systems.
In this work, I explore the relationship between the structure and mechanics of shallow plumbing systems and the volcanic eruptions these systems produce. I attempt to contribute to the understanding of this complex relationship by linking geological and geophysical observations of an eroded basaltic subvolcanic system, and the eruptive and tectonic activity of an active volcano, with mathematical models of magma ascent and stress transfer.
The remarkable exposures of the Carmel outcrop intrusions, near the San Rafael swell, southeast Utah, U. S. A., allow detailed geological and geophysical observations of the roots of volcanic conduits that emerge from a subhorizontal magma feeder reservoir. These observations reveal a new mechanism for magma ascent and eruption triggering through gravitational instabilities created from an underlying feeding sill, and shed light on the mechanics of sill emplacement. Geophysical and geological observations of the 1999 and xii 1992 eruptions of the Cerro Negro volcano, Nicaragua, are used to explore the coupling between changes in the stress field and the triggering of volcanic eruptions, and magma ascent through the shallow crust. Modeling results of stress transfer and conduit flow highlight the importance of the surrounding stress field and geometry of the volcanic conduits that comprise shallow plumbing systems.
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García, Araujo Víctor. "Propuesta urbano-arquitectónica para Santa Cruz Cuatenco: Una visión desde la geometría fractal." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2020. http://hdl.handle.net/20.500.11799/111237.
Abstract:
Como punto de partida, se llevó a cabo un diagnóstico Urbano-Arquitectónico en el territorio de Santa Cruz Cuahutenco, para detectar las principales necesidades de la comunidad. En el siguiente mapa (ver imagen 1) se sintetizan las 4 necesidades principales que se requiere atender.
El presente trabajo ha sido desarrollado, a partir de una visión transdisciplinaria, con la finalidad de integrar a la investigación conceptos extrapolados de disciplinas como la física, la geometría y las matemáticas, que permitan visualizar los fenómenos urbano-arquitectónicos de la ciudad compleja del siglo XXI desde otro ángulo de visión.
En el capítulo I, se estudian conceptos relacionados con el diseño urbano-arquitectónico y la geometría fractal, para determinar los patrones en común que permitan abordar metodológicamente el territorio.
En el capítulo II, se realiza un diagnóstico general del medio físico natural, artificial y social, de la comunidad de Santa Cruz Cuahutenco, según los conceptos definidos en el capítulo uno, para detectar las áreas de oportunidad en las que se puede intervenir.
En el capítulo III, se analiza el territorio, tanto del uso de suelo existente como del área construida, la normatividad vigente y sus indicadores sociales. Se conceptualiza un proyecto urbano-arquitectónico a partir de iteraciones y se determina la estrategia urbana a implementar.
En el capítulo IV, se desarrolla la propuesta urbano-arquitectónica para la localidad de Santa Cruz Cuahutenco, la cual contempla un eje oriente-poniente (que articula 4 puntos clave de la comunidad) y un eje norte-sur (que revitaliza una sección del Río que atraviesa la población). De esta manera es como se genera un plano cartesiano.
La metodología que se establece en esta investigación consiste en entender los sistemas como conjuntos compuestos de 3 elementos: patrones de espacialidad, patrones de temporalidad y patrones de materialidad, que son necesarios e inseparables para que pueda acontecer algo.
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Genuys, Grégoire. "Non-commutative homometric musical structures and chord distances in geometric pitch spaces." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066576/document.
Abstract:
Nous étudions deux thématiques principales : l'homométrie non-commutative dans des produits semi-directs, et une notion de distance entre accords musicaux. deux melodies sont dites homométriques si elles possèdent le même ensemble d'intervalles : nous transposons cette notion a un enchainement d'accords et plus généralement a des produits semi-directs, ce qui permet d'élaborer un cadre pour l'étude de l'homométrie dans des groupes non-commutatifs, tels que le groupe diédral. nous définissons dans une deuxième partie une mesure de distances entre des accord musicaux n'ayant pas le même nombre de notes, a partir d'une distance basée sur le concept de voice-leadingWe study two main topics: non-commutative homometry and the notion of distance between musical chords. Two melodies are homometric if they share the same set of intervals. We transpose this notion to a chord sequence and more generally to semi-direct products, which allows to build a framework for the general study of homometry in non-commutative groups, such as the dihedral group. In the second part we define a mesure of distance between musical chords of different cardinalities, from a distance based on the notion of voice-leading
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MEJÍA, QUEVEDO ARMANDO. "EL APUNTE FILOSÓFICO EN LA GEOMETRÍA DEL CAOS DE MAURICIO MOLINA: UNA LECTURA DE LA POSMODERNIDAD." Tesis de Licenciatura, UNIVERSIDAD AUTÓNOMA DEL ESTADO DE MÉXICO, 2020. http://hdl.handle.net/20.500.11799/109544.
Abstract:
La intención primordial de este trabajo es demostrar la presencia de un discurso filosófico como trasfondo en la estructura narrativa de La geometría del caos. Las diferentes estrategias estilísticas presentes en el texto conducen a una lectura a partir de la denominada lógica de juego y la definen como herramienta de interpretación. La posmodernidad vista como el espacio de la narración permite la puesta en escena de las implicaciones del azar, la búsqueda de sentido a partir de la alteridad y la evasión del vértigo que ocasiona el sinsentido en los individuos posmodernos.
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Zaoui, Mohammed. "Etude experimentale de la combustion du charbon pulverise dans un four vertical a geometrie simplifiee suivi d'echangeurs, recherche des parametres de marche en fonction des differentes caracteristiques des combustibles et des parametres de conduite." Paris, ENMP, 1988. http://www.theses.fr/1988ENMP0107.
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Santos, Jessé Baptista Veronese dos. "Influência nas características do escoamento em função da alteração da geometria do conduto a jusante de válvula tipo segmento invertida em sistema de enchimento e esvaziamento de eclusas de navegação." Universidade do Vale do Rio dos Sinos, 2012. http://www.repositorio.jesuita.org.br/handle/UNISINOS/3268.
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Submitted by Mariana Dornelles Vargas (marianadv) on 2015-04-09T18:40:24Z
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influencia_caracteristicas.pdf: 5180915 bytes, checksum: df667ffda685e6774d46e64735e32e82 (MD5)Made available in DSpace on 2015-04-09T18:40:25Z (GMT). No. of bitstreams: 1 influencia_caracteristicas.pdf: 5180915 bytes, checksum: df667ffda685e6774d46e64735e32e82 (MD5) Previous issue date: 2012
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Este trabalho apresenta um estudo de comportamento fluidodinâmico na operação de válvula do tipo segmento invertida, utilizadas em sistemas de enchimento e esvaziamento de navegação de eclusas. Nesta pesquisa é verificada a influência da alteração geométrica no conduto a jusante da comporta. O objetivo principal é encontrar dentre alterações geométricas aquela que oferece melhores condições de operação, isto é, minimizando os efeitos nocivos provocados pelas baixas pressões. O estudo é realizado através de abordagem numérica (CFD -Computer Fluid Dynamics), com o software comercial ANSYS-CFX, utilizando-se as equações da conservação da massa e quantidade de movimento como modelo básico. Foram simulados 3 comprimentos de expansão (Lexp = 0,3, 0,6 e 0,9 m) no teto a jusante da comporta, mantendo a mesma inclinação (1E:10 Lexp, onde E é a elevação do teto). Para cada comprimento de expansão foram simuladas 3 vazões (Q) e 3 aberturas (a), totalizando 27 simulações.As comparações entre os resultados numéricos para as expansões propostas são realizadas a partir do modelo numérico (original) já validado em trabalhos publicados. Também são feitas análises de parâmetros, como: alterações geométricas, pressões mínimas, regiões do conduto submetidas à pressões críticas (negativas), recuperação da pressão, coeficientes de perda de carga e de contração. Estas análises permitiram observar qual a influência da expansão no escoamento, mostrando que a simulação numérica pode ser utilizada como de apoio na definição de novas geometrias a serem adotadas nos projetos de novas eclusas, bem como na avaliação de eclusas já existentes identificando condições de operação nocivas na região junto a comporta. Verifica-se neste trabalho que as alterações geométricas propostas não são capazes de resolverem os problemas relativos às pressões negativas, e que seu desempenho depende das condições operação (principalmente a vazão). Contudo, quanto maiores forem as vazões, maiores serão as pressões mínimas obtidas com a expansão para o teto. Espera-se que os resultados obtidos possam ser usados como base para projetos, visando à diminuição dos efeitos nocivos na válvula (como cavitação, vibrações, erosões, ruídos e esforços espasmódicos) e perturbações que danificam as embarcações, durante a operação dentro da eclusa.
This paper presents a study of fluid dynamic behavior in the operation of inverted Tainter gate, used in filling and emptying systems of navigation locks. In this research is verified the influence of geometric change in the conduit downstream of the gate. The main objective is to find among geometric changes one that offers the best operating condition, i.e., minimizing the harmful effects of low pressures. The study is conducted through numerical approach (CFD-Computer Fluid Dynamics) with the commercial software ANSYS-CFX, using the equations of conservation of mass and momentum as the basic model. Were simulated 3 expansion lengths (Lexp = 0.3, 0.6 and 0.9 m) in the roof of downstream gate, keeping the same slope (1E:10 Lexp, where E is the elevation of the roof). For each expansion length were three simulated stream flow (Q) and 3 openings (a), totaling 27 numerical simulations. Comparisons between the numerical results for the proposed expansions are made from the numerical model (original) previously validated in published works. Also analysis are made of parameters such as geometric changes, minimum pressures, the conduit regions undergoing critical pressures (negative) pressure recovery, pressure loss and contraction coefficients. This analysis allowed observing the influence of the expansion in the flow, showing that the numerical simulation can be used to support the definition of new geometries to be adopted in the design of new navigation locks, as well as evaluation of existing locks, identifying the harmful operating conditions in the region near the gate. It is verified in this work that the geometric changes proposed are not able to solve the problems relating to negative pressures, and its performance depends on operating conditions (mainly the flow). However, the higher the flow rate, the greater the pressures obtained with minimal expansion to the roof. It is hoped that the results obtained can be used as a basis for projects in order to reduce the harmful effects on the valve (as cavitation, vibration, erosion, noise and spasmodic efforts) and disorders that damage the vessels, while operating within the lock.
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Sobral, Luís Filipe da Costa. "Estudo numérico de um escoamento laminar de um fluido newtoniano em condutas de secção não circular com curvatura de 90º." Master's thesis, 2013. http://hdl.handle.net/10216/72690.
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Sobral, Luís Filipe da Costa. "Estudo numérico de um escoamento laminar de um fluido newtoniano em condutas de secção não circular com curvatura de 90º." Dissertação, 2013. http://hdl.handle.net/10216/72690.
Books on the topic "Conduit geometry":
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Descartes, René. Discours de la methode: Pour bien conduire sa raison, & chercher la verité dans les sciences : plus la dioptrique, les meteores et la geometrie qui sont des essais de cete methode. Lecce: Conte, 1987.
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Descartes, René. Discours de la méthode: Pour bien conduire sa raison, & chercher la vérité dans les sciences ; Plus, La Dioptrique ; Les Météores ; et, La Géométrie ; qui sont des essais de cette méthode. Lecce: Università degli Studi di Lecce, Dipartimento di Filosofia, 1987.
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Descartes, René. Discours de la méthode: Pour bien conduire sa raison, & chercher la vérité dans les sciences ; Plus, La Dioptrique ; Les Météores ; et, La Géométrie ; qui sont des essais de cette méthode. Lecce: Università degli Studi di Lecce, Dipartimento di Filosofia, 1987.
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Descartes, René. Discours de la méthode: Pour bien conduire sa raison et chercher la vérité dans les sciences ; plus La dioptrique, Les météores et la géométrie qui sont des essais de cette méthode. Paris: Fayard, 1986.
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Descartes, René. Discours de la méthode: Pour bein [sic] conduire sa raison et chercher la verité dans les sciences = Discourse on the method : of conducting one's reason well and of seeking the truth in the sciences : a bilingual edition and an interpretation of René Descartes' philosophy of method. Notre Dame: University of Notre Dame Press, 1994.
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Paciorek, Andrew. Art for Mindfulness - Geometric Designs. Harper Thorsons, 2015.
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Emam, Moataz H. Covariant Physics. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198864899.001.0001.
Abstract:
This book is an introduction to the modern methods of the general theory of relativity, tensor calculus, space time geometry, the classical theory of fields, and a variety of theoretical physics oriented topics rarely discussed at the level of the intended reader (mid-college physics major). It does so from the point of view of the so-called principle of covariance; a symmetry that underlies most of physics, including such familiar branches as Newtonian mechanics and electricity and magnetism. The book is written from a minimalist perspective, providing the reader with only the most basic of notions; just enough to be able to read, and hopefully comprehend, modern research papers on these subjects. In addition, it provides a (hopefully short) preparation for the student to be able to conduct research in a variety of topics in theoretical physics; with particular emphasis on physics in curved spacetime backgrounds. The hope is that students with a minimal mathematical background in calculus and only some introductory courses in physics may be able to study this book and benefit from it.
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Discours de la methode pour bien conduire sa raison, et chercher la verité dans les sciences : plus la dioptrique, les meteores et la geometrie qui sont des essais de cete methode. - 1. edición. Fayard, 1986.
Book chapters on the topic "Conduit geometry":
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Blatnik, Matej, David C. Culver, Franci Gabrovšek, Martin Knez, Blaž Kogovšek, Janja Kogovšek, Hong Liu, et al. "Deciphering Epiphreatic Conduit Geometry from Head and Flow Data." In Advances in Karst Science, 149–68. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-26827-5_8.
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Auterives, Chrystelle, Stéphane Binet, and Patrick Albéric. "Inferred Conduit Network Geometry from Geological Evidences and Water-Head in a Fluvio-Karstic System (Val D’Orleans, France)." In H2Karst Research in Limestone Hydrogeology, 49–58. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-06139-9_3.
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Wilson, Lionel, and James W. Head. "Nature of Local Magma Storage Zones and Geometry of Conduit Systems Below Basaltic Eruption Sites: Pu'u 'O'o, Kilauea East Rift, Hawaii, Example." In Collected Reprint Series, 14785–92. Washington, DC: American Geophysical Union, 2014. http://dx.doi.org/10.1002/9781118782064.ch28.
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Knura, Martin, and Jochen Schiewe. "Improvement of Task-Oriented Visual Interpretation of VGI Point Data." In Volunteered Geographic Information, 199–217. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-35374-1_10.
Abstract:
AbstractVGI is often generated as point data representing points of interest (POIs) and semantic qualities (such as accident locations) or quantities (such as noise levels), which can lead to geometric and thematic clutter in visual presentations of regions with numerous VGI contributions. As a solution, cartography provides several point generalization operations that reduce the total number of points and therefore increase the readability of a map. However, these operations are applied rather general and could remove specific spatial pattern, possibly leading to false interpretations in tasks where these spatial patterns are of interest. In this chapter, we want to tackle this problem by defining task-oriented sets of map generalization constraints that help to maintain spatial pattern characteristics during the generalization process. Therefore, we conduct a study to analyze the user behavior while solving interpretation tasks and use the findings as constraints in the following point generalization process, which is implemented through agent-based modeling.
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Badano, Luigi, and Denisa Muraru. "Functional anatomy of atria." In ESC CardioMed, edited by Yen Ho, 88–92. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0017.
Abstract:
The left and right atria are dynamic structures that play an integral role in cardiac performance by modulating the respective ventricular filling. This function is accomplished by their role as a reservoir for venous return during ventricular systole, a conduit for venous return during early ventricular diastole, and a booster pump for ventricular filling during late diastole. Recent advances in cardiac imaging allow the accurate assessment of the geometry and phasic functions of both atria. Two- and three-dimensional echocardiography enables a volumetric analysis of atrial function, and both Doppler tissue imaging and speckle-tracking echocardiography allow the assessment of the deformation of atrial myocardium.
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Furbish, David Jon. "Dimensional Analysis and Similitude." In Fluid Physics in Geology. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195077018.003.0009.
Abstract:
Some fluid flow problems are sufficiently simple that they can be treated mathematically in a straightforward way, making use of definitions of physical quantities, and taking into account initial and boundary conditions. For example, our derivation of the average velocity in a conduit with parallel walls (Example Problem 3.7.1) was obtained in a straightforward way once we specified the geometry of the problem, then made use of the definition of a Newtonian fluid and the no-slip condition. Whereas this type of analysis may work for some problems, it would be misleading to think that such direct approaches to solving problems are, in principle, always possible, hinging only on one’s mathematical skills and adeptness in specifying the geometry of a problem. Herein arise two noteworthy points. First, when initially examining a problem, one can sometimes obtain a clear idea of the desired solution before attempting a formal mathematical analysis. The means to do this, as we shall see below, is supplied by dimensional analysis, and it is a strategy that ought to be adopted in many circumstances. In fact, it is worth noting that dimensional analysis underlies many of the problems presented in this text. The advantage of knowing the form of a desired solution, of course, is that one has a clear target to guide the subsequent mathematical analysis. Indeed, this is the vantage point from which many classic problems, for example Stokes’s law for settling spheres, were initially examined. Second, a complete mathematical formulation of a problem may not be possible, due to the complexity of the problem, or due to absence of information required to constrain the mathematics of the problem. As a simple example, suppose that we were unaware of the no-slip condition in our analysis of the conduit-flow problem (Example Problem 3.7.1). Our analysis in this case would have essentially ended with (3.70), with the constant of integration C undetermined. Nevertheless, we could get close to our result (3.75) for the average velocity by another way.
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Ioannides, Yannis M. "Social Interactions and Urban Spatial Equilibrium." In From Neighborhoods to Nations. Princeton University Press, 2012. http://dx.doi.org/10.23943/princeton/9780691126852.003.0005.
Abstract:
This chapter explores what the interactions of individuals and firms in their vicinity and in broader communities reveal about the spatial structure of cities as self-organization by agents. It first introduces a benchmark, the Alonso–Mills–Muth model of a city in its bare essentials, and examines its implications for urban density and the associated pattern of land prices in the case with a predetermined center, the central business district (CBD). It then considers the geometry of spatial equilibrium when there is no predetermined center and social interactions are dispersed, along with the location decisions of firms in urban space, monocentric versus polycentric models of the urban economy, and the Lucas–Rossi-Hansberg models of urban spatial structure with productive externalities. It also analyzes neighborhood effects, urban equilibrium when proximity is a conduit for the transmission of job-related information, and the link between choice of job matching and spatial structure.
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"Variable Geometry, Justice and Home Affairs and the Conduct of eu External Relations." In The EU as a Global Actor - Bridging Legal Theory and Practice, 337–61. Brill | Nijhoff, 2017. http://dx.doi.org/10.1163/9789004347175_016.
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Queiroz, Kamila Fernanda F. da C., Marcus Costa de Araújo, Nadja Accioly Espíndola, Ladjane C. Santos, Francisco G. S. Santos, and Rita de Cássia Fernandes de Lima. "Developing and Using Computational Frameworks to Conduct Numerical Analysis and Calculate Temperature Profiles and to Classify Breast Abnormalities." In Biomedical Computing for Breast Cancer Detection and Diagnosis, 230–49. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-3456-4.ch011.
Abstract:
In this chapter, computational tools that have been designed to analyze and classify infrared (IR) images will be presented. The function of such tools is to interconnect in a user-friendly way the algorithms that are used to map temperatures and to classify some breast pathologies. One of these performs texture mapping using IR breast images to relate temperatures measured to the points over the substitute tridimensional geometry mesh. Another computer-aided diagnosis (CAD) tool was adapted so that it could be used to evaluate individual patients. This methodology will be used when the computational framework approach for classification is described. Finally, graphical interfaces and their functionalities will be presented and explained. Some case studies will be presented in order to verify whether or not the computational classification framework is effective.
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Finney, John. "5. The anomalies explained." In Water: A Very Short Introduction, 77–91. Oxford University Press, 2015. http://dx.doi.org/10.1093/actrade/9780198708728.003.0005.
Abstract:
‘The anomalies explained’ considers why water behaves differently from most other liquids and why this is so important chemically, biologically, and environmentally. Ice contracts on melting; a normal liquid expands. Below 4°C liquid water contracts on heating; a normal liquid expands. Between the melting point and 46°C, water’s compressibility falls as temperature increases; for a normal liquid it increases. Water’s viscosity at or below about 30°C falls as pressure increases from 1 to 1,000 atmospheres; it increases for a normal liquid. The local intermolecular geometry is responsible for these ‘anomalies’. The electrical properties of the water molecule result in other distinct properties: water is a very powerful solvent and it conducts electricity.
Conference papers on the topic "Conduit geometry":
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Kim, Moon, Mingqiang Yi, Jihua Zhong, Haim H. Bau, Howard Hu, and Suresh G. K. Ananthasuresh. "The Fabrication of Flow Conduits in Ceramic Tapes and the Measurement of Fluid Flow Through These Conduits." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-1239.
Abstract:
Abstract Ceramic tape and thick film technologies provide a convenient and flexible means for the fabrication of three-dimensional flow conduits integrated with sensing and actuating elements. In their pre-fired (green) state, the ceramic tapes are soft, pliable, and easily machinable. CNC, laser, or chemical machining can be used to fabricate fluid conduits. Various conduit geometries were machined ranging from straight conduit segments with various angles between them to arcs to spirals. Subsequent to the machining process, tapes with different planar features were aligned, stacked, and laminated to form complex three-dimensional flow paths. The paper describes the fabrication techniques and capabilities. Additionally, results of preliminary liquid flow measurements and simulations are reported for the pressure drop as a function of conduit geometry and flow rate in straight and L-shaped channels.
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Lee, Bong Joo, and J. R. Culham. "Effectiveness Analysis of Non-Mechanical Micro-Valvular Conduit in Single Phase Flow." In ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icnmm2012-73045.
Abstract:
The non-mechanical valvular conduit, which uses no moving parts but instead relies on a complex geometry to regulate flow, is studied through a combination of numerical, computational and experimental methods. This study is based on using water as the fluid at standard state properties. A numerical model is developed to evaluate the effectiveness of the non-mechanical valve’s intricate geometry. Then computational simulations of the oscillating/pumping sequence of the valvular conduit are conducted to examine the effectiveness of the valve when placed in use for a diaphragm pump. Results demonstrate that the non-mechanical valvular conduit can be an effective application for a diaphragm pump at the micro or macro-scale without requiring valvular mechanics. In computational simulations, when non-mechanical valves are positioned at both the inlet and exit of a diaphragm, the positive circulation of fluid is enhanced by 38% which is sufficient to meet the thermal dissipation requirements of an Intel Pentium D processor (i.e. 130 W). In addition, the experimental results in steady state condition demonstrated that the valvular design regulates the flow direction by producing diodicity (a measure of favorable flow direction) of 2.44.
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Shaffer, Nicholas, Francis Loth, Oliver Wieben, Brandon Rocque, Bermans Iskandar, and John Oshinski. "Impedance to Cerebrospinal Fluid Flow in the Cervical Spinal Canal is Dominated by Geometric Complexity." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53642.
Abstract:
In a fluid system, longitudinal impedance (LI) is the impedance per unit length of a conduit. Its magnitude depends on conduit geometry and the mechanical properties of both the fluid and conduit. In the context of vein grafts, LI has been shown to correlate with vein graft size and graft patency at one year from surgery [1]. More generally, LI has been shown to be consistent over a wide range of physiological flows [2]. Due to its ability to characterize the effect of geometry on flow in a conduit, LI may be useful in examining differences between a healthy spinal canal and one affected by Type I Chiari malformation (CMI). CMI is a complex disorder of the craniospinal system classically characterized by herniation of the cerebellar tonsils of 3–5 mm past the foramen magnum [3], which has proven difficult to properly diagnose as the associated neurological symptoms may overlap with the symptomatology of other disorders. Current methods of quantifying CMI severity, such as cerebellar tonsil herniation depth, do not necessarily correlate with symptom severity. Likewise, studies that have sought to hydrodynamically analyze CMI by measuring cerebrospinal fluid (CSF) velocity have yielded mixed results. We hypothesized that the severity of obstruction to CSF flow in the CMI-affected cervical spinal canal can be quantified and compared by calculation of LI.
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Rhodes, Abby G., Matthew D. Covington, and Joshua M. Blackstock. "UTILIZING CONSERVATIVE AND NON-CONSERVATIVE TRACERS TO ESTIMATE CONDUIT GEOMETRY: PRELIMINARY RESULTS FROM EXPERIMENTS AT SAVOY EXPERIMENTAL WATERSHED, NORTHWEST ARKANSAS (USA)." In GSA Annual Meeting in Phoenix, Arizona, USA - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019am-340801.
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Hashemi, Saeed, and William Durfee. "Variable Hydraulic Transmission to Be Used in a Body-Powered Wearable Robot." In 2020 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/dmd2020-9063.
Abstract:
Abstract A body-powered wearable robot (BPWR) transmits power from one joint to another in an exoskeleton. A variable hydraulic transmission design using long-stroke rolling diaphragm cylinders and efficient on/off valves is suggested in this paper to be used in a BPWR. Using the new design, a high number of transmission ratios are achievable in a smooth mechanism. The number of transmission ratios with respect to the number of cylinders and the pressure drop across the transmission is assessed. The torque loss caused by the pressure drop is 5 percent using a proper conduit geometry.
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Fadl, Ahmed, Stefanie Demming, Zongqin Zhang, Stephanus Bu¨ttgenbach, Manfred Krafczyk, and Donna M. L. Meyer. "A Valve-Less Rectification Minipump Based on Dynamic Rectifying Geometries." In ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels collocated with 3rd Joint US-European Fluids Engineering Summer Meeting. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30821.
Abstract:
The advantages of valve-less rectification micro pumps include having no moving parts, low cost, reliable, having the ability to pump particles-laden fluids and live cells, being compatible with a wide range of micro channel materials and working fluids. Most valve-less rectification micro pumps are based on passive rectifying geometries such as a nozzle/diffuser, Tesla (Valvular Conduit), and Bifurcation geometries. In this study, we present a new valve-less rectification minipump based on a dynamic rectifying geometry. The present work includes design, fabrication, and testing of the pump. The experimental results are presented in terms of flow rates and maximum back pressures.
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Osorio, Andres F., Alain J. Kassab, Eduardo A. Divo, I. Ricardo Argueta-Morales, and William M. DeCampli. "Computational Fluid Dynamics Analysis of Surgical Adjustment of Ventricular Assist Device Implantation to Minimize Stroke Risk." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12813.
Abstract:
Presently, mechanical support is the most promising alternative to cardiac transplantation. Ventricular Assist Devices (VADs) were originally used to provide mechanical circulatory support in patients waiting planned heart transplantation (“bridge-to-transplantation” therapy). The success of short-term bridge devices led to clinical trials evaluating the clinical suitability of long-term support (“destination” therapy) with left ventricular assist devices (LVADs). The first larger-scale, randomized trial that tested long-term support with a LVAD reported a 44% reduction in the risk of stroke or death in patients with a LVAD. In spite of the success of LVADs as bridge-to-transplantation and long-term support. Patients carrying these devices are still at risk of several adverse events. The most devastating complication is caused by embolization of thrombi formed within the LVAD or inside the heart into the brain. Prevention of thrombi formation is attempted through anticoagulation management and by improving LVADs design; however there is still significant occurrence of thromboembolic events in patients. Investigators have reported that the incidence of thromboembolic cerebral events ranges from 14% to 47% over a period of 6–12 months. An alternative method to reduce the incidence of cerebral embolization has been proposed by one of the co-authors, namely William DeCampli M.D., Ph.D. The hypothesis is that it is possible to minimize the number of thrombi flowing into the carotid arteries by an optimal placement of the LVAD outflow conduit, and/or the addition of aortic bypass connecting the ascending aorta (AO) and the innominate artery (IA), or left carotid artery (LCA). This paper presents the computational fluid dynamics (CFD) analysis of the aortic arch hemodynamics using a representative geometry of the human aortic arch and an alternative aortic bypass. The alternative aortic bypass is intended to reduce thrombi flow incidence into the carotid arteries in patients with LVAD implants with the aim to reduce thromboembolisms. In order to study the trajectory of the thrombi within the aortic arch, a Lagrangian particle-tracking model is coupled to the CFD model. Results are presented in the form of percentage of thrombi flowing to the carotid arteries as a function of LVAD conduit placement and aortic bypass implantation, revealing promising improvement.
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Anayiotos, Andreas S., Pedro D. Pedroso, Ramakrishna Venugopalan, Evangelos Eleftheriou, and Maria A. Advincula. "Flow Evaluation of a Compliant Coronary Artery Anastomosis Model." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/bed-23123.
Abstract:
Abstract Coronary artery bypass grafting (CABG) is a common surgical procedure for coronary artery diseases or severe stenosis of the coronary arteries. It makes use of a peripheral vein (usually the saphenous vein of the leg) to form a conduit between the aorta and the coronary artery distal to the obstructive lesion. It is rapidly becoming the treatment of choice in cases where the vessel is more than 70% occluded or when angioplasty is not possible. However, a significant number of grafts subsequently fail due to acute thrombosis in the early post-operative period or to restenosis within months or years. Intimal thickening in the CABG anastomosis has been implicated as the major cause of restenosis and long-term graft failure. Several studies point to the interplay between non-uniform hemodynamics (including disturbed flows and recirculation zones), wall shear stress, and long particle residence time as possible etiologies. An important feature of the anastomosis geometry, is a bulge that forms at the veno-arterial junction. This sinus forms as a result of the stretching of the thin venous wall when the graft is exposed to aortic pressure conditions. The resultant sinus, and the impedance mismatch of the vein-artery connection, contribute to a complicated region of highly disturbed flow at the divider and may have a primary role in restenosis and final failure of the graft.
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Ramiro Amorim, Andre, Felipe Oliveira Ribeiro, Rodrigo Klim Gomes, Peyman Asgari, Rodrigo Do Nascimento Carvalhal, and Alexandre Rezende Diezel. "Gimbal Joint Riser – A Novel Concept: Experimental Hydrodynamic Coefficients." In ASME 2023 42nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/omae2023-103189.
Abstract:
Abstract Gimbal Joint (GJ) is a device designed to connect the upper and lower parts of a steel riser in a free-hanging system. The mechanism consists of a flexible conduit, inside a structure that is made of several hinged connection elements, making the whole system work as an articulation. Hydrodynamic properties of GJ are recognized as an uncertainty source due to its novelty and very specific geometry. Recently, an experimental campaign of a model scale size — 1:9 — has been performed as a part of technology qualification programme. The forced oscillation tests focused on obtaining drag and hydrodynamic inertia coefficients of the GJ, as a recommended practice to estimate hydrodynamic coefficients of complex bodies. As an oscillating porous body, the hydrodynamic coefficients shall be assessed in terms of the Keulegan Carpenter number, at different flow regimes corresponding to varying Reynolds number. The focus of this paper is to present and discuss the hydrodynamic coefficients obtained in the forced oscillation tests. A discussion about the correlated effect of the model porosity and KC (Keulegan-Carpenter number) compared to Sarpkaya’s experiment from the literature is also presented. Results indicate that porosity changes significantly the hydrodynamic coefficients, providing that standard industry coefficients, normally used in dynamic analysis, shall not be used when GJ is part of the system.
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Governo, André, and Bayindir H. Saracoglu. "Multidisciplinary Optimization of Radial Outflow Turbines With Highly Deformable Blades." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-84333.
Abstract:
Abstract Miniature radial outflow turbines are used to generate onboard power for various aerial devices using the ram effect. The incoming air flow axially entering the inlet conduit of the turbine housing spins the turbine rotor, which may have excessive tip gap and a sizable hub cavity, and radially discharges from the turbine flow passages. The current class of turbine rotors under investigation are typically made of polymeric materials for serial production at reduced cost. The turbine airfoils are designed with significant overhanging sections over the large hub cavity. Such configuration allows regulating the rotational speed of the rotor, at high inlet velocity conditions, by enabling the rear part of the blades to bend under the effect of centrifugal and fluidic forces. However, such deflections may lead to material non-linearities and strongly affect the flow development through the blade passages, which are not yet documented in the open literature. This paper investigates the complex flow field inside such turbines for a wide range of operating conditions. A multidisciplinary design optimization routine was utilized to assess the conflicting influence of the aerodynamical and structural performance for this class of turbines. The strategy utilizes an in-house metamodel-assisted optimizer (CADO) based on artificial neural networks and genetic algorithms to maximize the power output while evaluating the impact of the rotational speed on blade displacement and flow behaviour. A decoupled fluid-structure interaction approach was established in the computational fluid dynamics solver integrated with the optimizer. The methodology validation was achieved through the experimental results on high-speed blade deformation of the initial turbine mockup. The results show striking changes to turbine geometry mainly dictated by the centrifugal force as compared to the fluidic loads play when a hub cavity exists. A change in the blade loading is identified due to the three-dimensional geometric modifications of the rotor under load solicitations and connected with a modification of the incidence angle and profile curvatures. Such a process decreases the turbine’s efficiency, especially at very high rotational speeds. The results of this work provide a comprehensive design space and guidelines on the development of radial outflow turbines through the extensive optimization study for preliminary design choices for turbines with similar geometries.
Reports on the topic "Conduit geometry":
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Danican(archived), Li. PR218-173602-R01 Assessment of Fitness-for-Service for Crack-within-Corrosion Anomalies. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), May 2020. http://dx.doi.org/10.55274/r0011675.
Abstract:
Continuous crack defects in corroded areas of pipe have been identified as potential cause failures and significant accidents. PRCI was tasked with providing a model to pipeline operators with detailed step-by-step procedures for evaluating the effect of interacting corrosion and crack threats on the integrity of pipelines. There are several existing assessment methodologies for different types of anomaly such as blunt type and crack-like type. The predicted failure pressure PFP results from existing assessment methods were compared and reviewed in this research. Finite Element Analysis (FEA) is a well-documented tool for the accurate assessment of crack-in-corrosion (CIC). Hence, FEA was used in this research to conduct the PFP assessment the results of which were verified with burst tests performed at the Kiefner laboratory as well as data from previous PRCI research: PR-186-113600, Grinding Limits for Repair of SCC on Operating Pipelines (see Ref 18). Additionally, data analytics methodology was used in conjunction with FEA results to develop a relationship between stress intensity and CIC geometry and material properties. The resultant data-analytics derived equation was subsequently verified against burst test results taken from Hosseini's 2010 publication (see Ref 3 and Ref 4).
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Harris, L. B., P. Adiban, and E. Gloaguen. The role of enigmatic deep crustal and upper mantle structures on Au and magmatic Ni-Cu-PGE-Cr mineralization in the Superior Province. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328984.
Abstract:
Aeromagnetic and ground gravity data for the Canadian Superior Province, filtered to extract long wavelength components and converted to pseudo-gravity, highlight deep, N-S trending regional-scale, rectilinear faults and margins to discrete, competent mafic or felsic granulite blocks (i.e. at high angles to most regional mapped structures and sub-province boundaries) with little to no surface expression that are spatially associated with lode ('orogenic') Au and Ni-Cu-PGE-Cr occurrences. Statistical and machine learning analysis of the Red Lake-Stormy Lake region in the W Superior Province confirms visual inspection for a greater correlation between Au deposits and these deep N-S structures than with mapped surface to upper crustal, generally E-W trending, faults and shear zones. Porphyry Au, Ni, Mo and U-Th showings are also located above these deep transverse faults. Several well defined concentric circular to elliptical structures identified in the Oxford Stull and Island Lake domains along the S boundary of the N Superior proto-craton, intersected by N- to NNW striking extensional fractures and/or faults that transect the W Superior Province, again with little to no direct surface or upper crustal expression, are spatially associated with magmatic Ni-Cu-PGE-Cr and related mineralization and Au occurrences. The McFaulds Lake greenstone belt, aka. 'Ring of Fire', constitutes only a small, crescent-shaped belt within one of these concentric features above which 2736-2733 Ma mafic-ultramafic intrusions bodies were intruded. The Big Trout Lake igneous complex that hosts Cr-Pt-Pd-Rh mineralization west of the Ring of Fire lies within a smaller concentrically ringed feature at depth and, near the Ontario-Manitoba border, the Lingman Lake Au deposit, numerous Au occurrences and minor Ni showings, are similarly located on concentric structures. Preliminary magnetotelluric (MT) interpretations suggest that these concentric structures appear to also have an expression in the subcontinental lithospheric mantle (SCLM) and that lithospheric mantle resistivity features trend N-S as well as E-W. With diameters between ca. 90 km to 185 km, elliptical structures are similar in size and internal geometry to coronae on Venus which geomorphological, radar, and gravity interpretations suggest formed above mantle upwellings. Emplacement of mafic-ultramafic bodies hosting Ni-Cr-PGE mineralization along these ringlike structures at their intersection with coeval deep transverse, ca. N-S faults (viz. phi structures), along with their location along the margin to the N Superior proto-craton, are consistent with secondary mantle upwellings portrayed in numerical models of a mantle plume beneath a craton with a deep lithospheric keel within a regional N-S compressional regime. Early, regional ca. N-S faults in the W Superior were reactivated as dilatational antithetic (secondary Riedel/R') sinistral shears during dextral transpression and as extensional fractures and/or normal faults during N-S shortening. The Kapuskasing structural zone or uplift likely represents Proterozoic reactivation of a similar deep transverse structure. Preservation of discrete faults in the deep crust beneath zones of distributed Neoarchean dextral transcurrent to transpressional shear zones in the present-day upper crust suggests a 'millefeuille' lithospheric strength profile, with competent SCLM, mid- to deep, and upper crustal layers. Mechanically strong deep crustal felsic and mafic granulite layers are attributed to dehydration and melt extraction. Intra-crustal decoupling along a ductile décollement in the W Superior led to the preservation of early-formed deep structures that acted as conduits for magma transport into the overlying crust and focussed hydrothermal fluid flow during regional deformation. Increase in the thickness of semi-brittle layers in the lower crust during regional metamorphism would result in an increase in fracturing and faulting in the lower crust, facilitating hydrothermal and carbonic fluid flow in pathways linking SCLM to the upper crust, a factor explaining the late timing for most orogenic Au. Results provide an important new dataset for regional prospectively mapping, especially with machine learning, and exploration targeting for Au and Ni-Cr-Cu-PGE mineralization. Results also furnish evidence for parautochthonous development of the S Superior Province during plume-related rifting and cannot be explained by conventional subduction and arc-accretion models.