Academic literature on the topic 'Coupled volumes'
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Journal articles on the topic "Coupled volumes"
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Moss, P., and E. D. Salin. "Flow Injection Preconcentration Coupled with Direct Sample Insertion for Inductively Coupled Plasma Atomic Emission Spectrometry." Applied Spectroscopy 45, no. 10 (December 1991): 1581–86. http://dx.doi.org/10.1366/0003702914335210.
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A flow injection (FI) preconcentration system has been coupled with a direct sample insertion (DSI) system for inductively coupled plasma atomic emission spectrometry (ICP-AES). The FI system provides a preconcentration factor of approximately 30. The DSI detection limit improvement, as compared to conventional nebulization detection limits, is element specific and ranges between 10 and 130 when a cup specifically designed for liquid work is used. The FI-DSI hybrid provides detection limit improvements ranging between 140 and 1200 for the elements tested—Cu, Pb, and Zn. Precision of the FI-DSI-ICP system averages 4% RSD for these three elements. FI processing time is 6.0 minutes with the use of 5-mL injection volumes. The system offers considerable potential for further improvement by increasing the injection volume and improving the interface to the DSI.
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Woszczyk, Wieslaw. "Synthesis of acoustics of coupled volumes—Perceptual approach." Journal of the Acoustical Society of America 149, no. 4 (April 2021): A116—A117. http://dx.doi.org/10.1121/10.0004697.
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McCall, Robert Timothy, Gerd Masselink, Dano Roelvink, Paul Russell, Mark Davidson, and Timothy Poate. "MODELLING OVERWASH AND INFILTRATION ON GRAVEL BARRIERS." Coastal Engineering Proceedings 1, no. 33 (October 25, 2012): 34. http://dx.doi.org/10.9753/icce.v33.currents.34.
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A quasi-3D process-based and time dependent groundwater model is developed and coupled to a hydrodynamic storm impact model to simulate the effect of infiltration on overwash on a gravel barrier. The coupled model is shown to accurately reproduce groundwater variations, runup properties and overwash time series measured in the gravel barrier during a large-scale physical model experiment. The coupled model is applied to study the influence of hydraulic conductivity on overwash volumes. It is shown that modeled overwash volumes are significantly affected by infiltration for hydraulic conductivity values greater than 0.01ms-1.
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Policastro, Steven A., Carlos M. Hangarter, Rachel M. Anderson, and Fritz Friedersdorf. "Effect of confined electrolyte volumes on galvanic corrosion kinetics in statically loaded materials." Corrosion Reviews 37, no. 5 (September 25, 2019): 521–31. http://dx.doi.org/10.1515/corrrev-2019-0016.
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AbstractThis work investigates the effects that the confined volume of atmospheric electrolytes has on the galvanic corrosion kinetics of a martensitic stainless steel alloy, UNS S13800, coupled with UNS A97075 in simulated atmospheric environments at relative humidity values that span the range of operational exposures. Restricted volumes found in thin films and droplets have been shown to control reduction reaction kinetics and are an ongoing challenge to characterize and standardize. This, along with the dynamic and high concentration of aggressive ions found in confined electrolytes, creates a unique corrosion system that requires a multifaceted approach to evaluate varied conditions, compare them with traditional measurements, and more accurately predict galvanic atmospheric corrosion. In this work, corrosion currents in galvanic couples were obtained under two environmental conditions: (1) bulk electrolytes, in a standardized test configuration, with chemistries relevant to atmospheric electrolytes; and (2) deliquesced droplets formed and equilibrated at a given temperature and relative humidity value. The corrosion currents for the same galvanic couple specimens were evaluated, using an atmospheric corrosion model, under a thin film electrolyte while statically loaded and unloaded, at two nominally different locations, e.g. Alexandria, VA, and Miami, FL, on the same date, using recorded weather conditions. The modeled corrosion currents were then compared with the currents obtained from the experimental conditions.
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Doria, Damian, Russell Johnson, Todd L. Brooks, and Ted Pyper. "Coupled volumes in concert hall: Not just reverberation chambers." Journal of the Acoustical Society of America 116, no. 4 (October 2004): 2553. http://dx.doi.org/10.1121/1.4785193.
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Nakajima, Tateo, and Todd L. Brooks. "Coupled volumes in concert halls—impact on spatial perception." Journal of the Acoustical Society of America 131, no. 4 (April 2012): 3491. http://dx.doi.org/10.1121/1.4709192.
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Doggett, Coleman A. "A Method to Assess Large-Scale Forest Damage: A Case Study." Southern Journal of Applied Forestry 17, no. 4 (November 1, 1993): 197–99. http://dx.doi.org/10.1093/sjaf/17.4.197.
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Abstract Large-scale forest disasters require rapid quantitative damage assessments. A method is presented of quickly acquiring statistically quantifiable damage data. The method involves systematic ground sampling coupled with the use of a geographic information system (GIS), which maps damage by criteria classes and determines acreage within each criteria class. These data are then expanded by average per-acre timber volumes obtained from USDA Forest Service statewide inventories and by mean losses within defined classes to determine volume losses. Volume losses are converted to dollar values by multiplying volumes by Timber Mart South (Norris 1989) stumpage values. South. J. Appl. For. 17(4):197-199.
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Niccolini Marmont Du Haut Champ, Carlo Alberto, Paolo Silvestri, Federico Reggio, Mario Luigi Ferrari, and Aristide Fausto Massardo. "Early surge detection in a mGT plant coupled with large volumes." E3S Web of Conferences 414 (2023): 02009. http://dx.doi.org/10.1051/e3sconf/202341402009.
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The present work features post-processing methods applied to vibro-acoustic data acquired from a T100 micro gas turbine (mGT) plant coupled with different volume interposed plenums. Such experimental campaign was conducted by relying on a test bench developed at the University of Genoa for hybrid systems emulation. Nonetheless, the obtained results can be generalized to all advanced cycles in which a mGT is coupled with further external elements which cause an increase of plant overall volume size. Since in this case a 100 kW mGT was employed, the interposed vessel was placed between heat recovery system outlet and combustor inlet, such as in common cases relevant to small size plants. Post-processing techniques carried out on acoustic and vibrational measurements can make available innovative diagnostic tools and predictive solutions by relying on appropriate instability indicators which are defined basing only on microphone and accelerometer experimental data. The main results presented in this work are relevant to rotating stall and incipient surge proper identification. Such investigation has been performed to increase the knowledge about such dangerous compressor working conditions; indeed, energy systems characterized by significant interposed volumes coupled with centrifugal compressors feature issues relevant to structural damaging due to surge and rotating stall.
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Tiryana, Tatang, Lailatul Khasanah, Priyanto Priyanto, Sri Rahaju, and Muhdin Muhdin. "FORM FACTORS AND VOLUME MODELS FOR ESTIMATING TREE BOLE VOLUME OF MAHOGANY AT COMMUNITY FORESTS IN CENTRAL JAVA." Indonesian Journal of Forestry Research 8, no. 2 (October 31, 2021): 199–211. http://dx.doi.org/10.20886/ijfr.2021.8.2.199-211.
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Form factors and volume models are often be used in the estimation of tree volumes. However, a few studies have developed and evaluated the accuracy of form factors and volume models for estimating tree volumes of community forests. This study aimed to formulate form factors and volume models and assess their prediction accuracy for estimating tree bole volumes of mahogany at community forests in Central Java. This study used 120 sample trees with diameters of 6–38 cm to formulate artificial and absolute form factors and to develop tree bole volume models. These form factors coupled with bole height and total height were used in simple volume equations. Regression analyses were used to develop volume models using the diameter and total height as predictors. The simple volume equations and volume models' prediction accuracy was evaluated using a cross-validation dataset and independent dataset (30 sample trees). The artificial form factor (0.68 ± 0.11) of mahogany, which was higher than the absolute form factor (0.46 ± 0.09), provided accurate estimates of tree bole volumes when it was used with the bole height instead of the total height. The volume model that uses diameter and total height produced the most accurate estimates, while the volume model that uses diameter alone provided the most practical yet reliable tool for estimating tree bole volumes of mahogany. The results of this study are useful for improving community forest management.
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Charchi, Negar, Ying Li, Margaret Huber, Elyahb Allie Kwizera, Xiaohua Huang, Christos Argyropoulos, and Thang Hoang. "Small mode volume plasmonic film-coupled nanostar resonators." Nanoscale Advances 2, no. 6 (2020): 2397–403. http://dx.doi.org/10.1039/d0na00262c.
Full textDissertations / Theses on the topic "Coupled volumes"
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Leclavier, Sarah. "Volumes finis et solutions renormalisées, applications à des systèmes couplés." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR029/document.
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On s’intéresse dans cette thèse à montrer que la solution approchée, par la méthode des volumes finis, converge vers la solution renormalisée de problèmes elliptiques ou paraboliques à donnée L1. Dans la première partie nous étudions une équation de convection-diffusion ellliptique à donnée L1. En adaptant la stratégie développée pour les solutions renormaliséesà la méthode des volumes finis, nous montrons que la solution approchée converge vers l’unique solution renormalisée.Dans la deuxième partie nous nous intéressons à un problème parabolique nonlinéaire à donnée L1. En utilisant une version discrète de résultats de compacité classiques, nous montrons que les résultats obtenues dans le cas elliptique restentvrais dans le cas parabolique. Dans la troisième partie nous montrons des résultats similaires pour une équationparabolique doublement non-linéaire à donnée L1. Le caractère doublement nonlinéaire de l’équation crée des difficultés supplémentaires par rapport à la partie précédente, notamment car la règle de dérivation en chaîne ne s’applique pas dansle cas discret. Enfin, dans la quatrième partie, nous utilisons les résultats établis précédemment pour étudier un système de type thermoviscoélasticité. Nous montrons que la solution approchée, obtenue par un schéma éléments finis-volumes finis, converge vers une solution faible-renormalisée du systèmeIn this thesis we are interested in proving that the approximate solution, obtained by the finite volume method, converges to the unique renormalized solution of elliptic and parabolic equations with L1 data. In the first part we study an elliptic convection-diffusion equation with L1 data. Mixing the strategy developed for renormalized solution and the finite volume method,we prove that the approximate solution converges to the unique renormalized solution. In the second part we investigate a nonlinear parabolic equation with L1 data. Using a discrete version of classical compactness results, we show that the results obtaines previously in the elliptic case hold true in the parabolic case. In the third part we prove similar results for a doubly nonlinear parabolic equation with L1 data. The doubly nonlinear character of the equation makes new difficulties with respect to the previous part, especially since the chain rule formula does not apply in the discrete case. Finaly, in the fourth part we use the results established previously to investigate a system of thermoviscoelasticity kind. We show that the approximate solution,obtaines by finite element-finite volume scheme, converges to a weak-renormalized solution of the system
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Simpson, Rupert Anthony. "The relative performance of scalable load balancing algorithms in loosely-coupled distributed systems. Available in 2 volumes." Thesis, Aston University, 1994. http://publications.aston.ac.uk/10672/.
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The computer systems of today are characterised by data and program control that are distributed functionally and geographically across a network. A major issue of concern in this environment is the operating system activity of resource management for different processors in the network. To ensure equity in load distribution and improved system performance, load balancing is often undertaken. The research conducted in this field so far, has been primarily concerned with a small set of algorithms operating on tightly-coupled distributed systems. More recent studies have investigated the performance of such algorithms in loosely-coupled architectures but using a small set of processors. This thesis describes a simulation model developed to study the behaviour and general performance characteristics of a range of dynamic load balancing algorithms. Further, the scalability of these algorithms are discussed and a range of regionalised load balancing algorithms developed. In particular, we examine the impact of network diameter and delay on the performance of such algorithms across a range of system workloads. The results produced seem to suggest that the performance of simple dynamic policies are scalable but lack the load stability of more complex global average algorithms.
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Neuhauser, Magdalena. "Development of a coupled SPH-ALE/Finite Volume method for the simulation of transient flows in hydraulic machines." Thesis, Ecully, Ecole centrale de Lyon, 2014. http://www.theses.fr/2014ECDL0045/document.
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L'utilisation croissante des sources d'énergie renouvelable avec une grande volatilité de production, comme l'énergie éolienne et solaire, conduit à des fluctuations dans le réseau électrique qui doivent être compensées. Pour cette raison les machines hydrauliques, turbines et pompes, sont plus souvent opérées dans les régimes de fonctionnement hors fonctionnement nominal et la fréquence des phases de démarrage et arrêt augmente. Ce type de fonctionnement peut avoir des conséquences importantes sur le cycle de vie des machines. Il est donc essentiel de prendre en compte l'écoulement dans les phases transitoires lors de la conception de la machine et la simulation numérique des écoulements est un outil adapté pour cela. La présente étude a pour objectif de développer une méthode de couplage flexible qui combine la méthode à maillage volumes finis (VF) et la méthode sans maillage Smoothed Particle Hydrodynamics - Arbitrary Lagrange Euler (SPH-ALE). Cette méthode couplée peut être utilisée comme outil pour l'investigation des phénomènes transitoires dans les machines hydrauliques. SPH-ALE est particulièrement bien adapté aux simulations des écoulements fortement dynamiques avec des géométries mobiles mais elle a des difficultés pour calculer des forts gradients de pression et vitesse. Un raffinement de particules est difficile à implémenter, surtout si les particules doivent être raffinées de manière anisotrope. Les méthodes volumes finis (VF) sont établies pour les simulations numériques d'écoulements grâce à leur stabilité et précision. Par contre, elles peuvent être lourdes pour les simulations avec des géométries mobiles et demandent souvent une interface entre des parties mobiles et statiques du maillage ce qui génère des erreurs supplémentaires. Pour combiner les deux approches complémentaires, une méthode de couplage a été développée qui décompose le domaine de calcul en zones où la vitesse et la pression sont calculées par la méthode VF, en zones où elles sont obtenues par SPH-ALE et en zones de recouvrement où les informations sont transférées de la zone VF à la zone SPH et inversement. Dans les zones de recouvrement les points de calcul VF sont utilisés comme voisins pour l'intégration en espace des particules SPH. Aux limites du maillage VF la vitesse et la pression sont interpolées des particules SPH, similairement aux méthodes Chimére des maillages recouvrants. Un logiciel SPH-ALE existant du groupe ANDRITZ est utilisé pour cette étude. Un solveur VF faiblement compressible est implémenté dans ce logiciel. Le solveur discrétise la même forme des équations de Navier-Stokes que le solveur SPH-ALE. Des solveurs de Riemann avec des états reconstruits par la méthode MUSCL sont employés. En outre, le solveur SPH-ALE est amélioré et adapté aux écoulements internes. Pour cette raison des conditions à l'entrée et à la sortie du type subsonique sont implémentées. Du plus, une méthode de correction du gradient de la fonction kernel est présentée qui améliore la précision du champ de pression, notamment si les particules ne sont pas distribuées régulièrement. La méthode couplée est validée à l'aide des cas test académiques en unidimensionnel et en bidimensionnel, comme le cas de tube à choc, les tourbillons de Taylor-Green et l'écoulement autour d'une aube symétrique du type NACA avec des particules en description eulérienne. En outre, le couplage offre la possibilité d'imposer des conditions à la sortie aux particules lagrangiennes. La méthode est appliquée aux simulations d'écoulement transitoire en 2D avec des particules qui se déplacent en suivant les géométries mobilesThe increased use of intermittent forms of renewable energy like wind and solar energy produces fluctuations in the electric grid that have to be compensated. For this reason, hydraulic machines like turbines and pumps are more often operated under non-conventional operating conditions and are submitted to frequent starts and stops. This type of operating conditions has important consequences on the life cycle of the machines. It is thus of paramount importance that transient flows at off-design conditions are properly taken into account in the design phase and numerical simulation is an appropriate way to do so. The present study aims at developing a flexible coupling method of the meshbased Finite Volume Method (FVM) and the meshless Smoothed Particle Hydrodynamics - Arbitrary Lagrange Euler (SPH-ALE) method, which can be used as a tool for the investigation of transient phenomena in hydraulic machines. SPH-ALE is very well adapted for the simulation of highly dynamic flows with moving geometries but has difficulties to correctly represent rapidly changing gradients of the field variables. Particle refinement is difficult to implement, especially if particles are refined in an anisotropic way. FV methods are well established in CFD because of their accuracy and stability. However, they can be tedious for simulations with moving geometries and often necessitate an interface between moving and static parts of the mesh which introduces additional errors. To overcome the shortcomings of both methods, a coupling method is developed that uses a decomposition of the computational domain into regions where the physical field variables are computed by the FV method, regions where they are computed by SPH-ALE and overlapping regions where the information is transferred from the FV domain to the SPH domain and vice versa. In the overlapping regions FV calculation points are used as neighbors for the SPH integration in space. At the boundaries of the FV mesh, velocity and pressure are interpolated from the SPH particles by means of scattered data interpolation techniques, similarly to Chimera methods for overlapping grids. For this study, an existing SPH-ALE software of the ANDRITZ Group is used. A weakly compressible FV solver is implemented into this software that discretizes the same form of the Navier-Stokes equations than the SPH-ALE solver. Similar to the present SPH-ALE method, Riemann solvers with reconstructed states, obtained by a MUSCL scheme, are employed. Moreover, adaptations and improvements of the SPH-ALE solver itself are made, which are important for the coupling and for the simulation of internal flows in general. Thus, subsonic inlet and outlet conditions are implemented. Furthermore, a correction method of the kernel gradient is presented that ensures zeroth order consistency of the SPH-ALE approximation of the divergence of the convective fluxes. The correction improves greatly the SPH pressure field on non-uniform particle distributions. The implemented coupled method is successfully validated by means of inviscid academic one-dimensional and two-dimensional testcases like a shock tube case, Taylor-Green vortices and the flow around a symmetric NACA airfoil with particles in Eulerian description. Furthermore, the coupling provides a possibility to implement outlet boundary conditions to Lagrangian moving SPH particles. It is then applied to the simulation of transient flows in rotor stator systems in 2D with moving particles
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Pietilä, Lars-Olof. "Molecular mechanics and force field studies of weakly coupled conjugated molecules and molecular crystals." Hki : Finnish Society of Sciences and Letters : Academic Bookstore [distr.], 1988. http://catalog.hathitrust.org/api/volumes/oclc/57854229.html.
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Scudeler, Carlotta. "Numerical modeling of flow and solute transport phenomena in subsurface and coupled surface-subsurface hydrology." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3421912.
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The overall aim of the work described in this thesis is to bring a number of contributions to hydrology and hydrological modeling in the framework of a specific physically-based numerical model for integrated surface subsurface and flow-transport processes, the CATchment-HYdrology Flow-Transport (CATHY_FT) model. These contributions revolve around three main themes: the enhancement of the numerical performance of hydrological models for flow and transport phenomena, the improvement of our current understanding of complex boundary conditions in order to reduce the errors associated with their modeling, and the testing and benchmarking of distributed physically-based models for groundwater flow and transport processes. The work to achieve the general objective is elaborated into four stages. First, the Larson-Niklasson post-processing algorithm is implemented in CATHY_FT to reconstruct mass-conservative velocities from a linear, or P1, Galerkin solution of Richards' equation. This is done to improve the accuracy and mass balance properties of the companion advective transport model (finite volume-based), which rely on accurate velocity fields as input. Through a comparison between the results from the reconstructed velocities and the P1 Galerkin velocities, it is shown that a locally mass-conservative velocity field is necessary to obtain accurate transport results. Second, a detailed and novel analysis of the behavior of seepage face boundaries is performed with the flow model of CATHY_FT. The numerical simulations examine the model's performance under complex conditions such as heterogeneity and coupled surface/subsurface flow. It is shown that the overall numerical solution can be greatly affected by the way seepage face boundaries are handled in hydrological models and that careful considerations are required when using simple approximations, in the presence of heterogeneous slopes, and for seepage faces forming on a portion of the land surface. Third, CATHY_FT is implemented and run at the Landscape Evolution Observatory of the Biosphere 2 facility, Arizona. A detailed modeling analysis is performed of the experimental data collected during an isotope tracer experiment and from an intensively-measured hillslope, including quantity and quality of groundwater discharge and point-scale flow and transport data. This flow and tracer data is used to incrementally explore complex phenomena and associated hypotheses (e.g., heterogeneity, fractionation, and dispersion), progressing from flow to transport and from integrated to point-scale response analysis. This incremental approach highlights the challenges in testing and validating the new generation of integrated hydrological models when considering many types and levels of observation data. Finally, a concluding analysis is performed that relates to all three themes of the thesis, describing some of the features of the CATHY_FT model, discussing key issues associated to its further development, and testing its physical and numerical behavior for both real and synthetic scenarios. This final stage of the thesis addresses the myriad challenges faced in accurately and efficiently resolving the difficult behavior of the advection-dispersion equation for subsurface solute transport, in properly handling the complex boundary conditions for solute interactions across the land surface, and generally in capturing process interactions and feedbacks between flow and transport phenomena in surface and subsurface environments.Lo scopo di questa tesi e' fornire dei contributi all'idrologia e alla modellazione idrologica nell'ambito di un modello numerico specifico, il modello CATchment HYdrology Flow-Transport (CATHY_FT), utilizzato per simulare processi integrati di superficie e sotterranei e di flusso e trasporto. Questi contributi riguardano tre temi principali: il miglioramento del comportamento numerico di modelli idrologici che simulano fenomeni di flusso e trasporto, l'approfondimento di condizioni al contorno complesse con l'obbiettivo di ridurre gli errori relativi alla loro modellazione e il test e l'analisi comparativa di modelli a base fisica utilizzati per simulare processi di flusso e trasporto sotterranei. Il lavoro per raggiungere l'obbiettivo generale viene diviso in quattro step. Nel primo step l'algoritmo di Larson-Niklasson e' implementato in CATHY_FT per ricostruire velocita' conservatrici della massa a partire da una soluzione lineare (o P1) di Galerkin dell'equazione di Richards, in modo da permettere al modello di trasporto avvettivo (basato sui volumi finiti) di conservare la massa, cosa che dipende strettamente dall'accuratezza del campo di velocita' che questo utilizza. Confrontando i risultati ottenuti con le velocita' derivanti dalla soluzione P1 di Galerkin e quelle ricostruite, viene mostrato che un campo di velocita' localmente conservativo e' necessario per ottenere risultati accurati con il trasporto. Nella seconda fase viene effettuata un'analisi dettagliata del comportamento delle condizioni ai limiti nella zona del fronte di infiltrazione con il modello di flusso di CATHY_FT. Le simulazioni numeriche esaminano il comportamento del modello in condizioni complesse come quelle di eterogeneita' e di flusso di superficie e sotterraneo accoppiato. Viene dimostrato che la soluzione numerica puo' essere fortemente influenzata dal modo in cui la zona di infiltrazione viene trattata nei modelli idrologici e che considerazioni accurate sono sempre necessarie quando si usano approssimazioni, in presenza di versanti eterogenei e per le zone di infiltrazione che si formano nella superficie terrestre. Come terzo step, CATHY_FT viene testato al Landscape Evolution Observatory del Biosphere 2 in Arizona. Viene eseguita un'analisi dettagliata di dati sperimentati raccolti durante un esperimento di tracciante isotopico e da un versante artificiale intensivamente controllato. Le informazioni comprendono la qualita' e la quantita' della portata sotterranea e dati puntuali di flusso e trasporto. Questi dati di flusso e tracciante sono utilizati per esplorare fenomeni complessi e le ipotesi associate (e.g., eterogeneita', frazionamento e dispersione), procedendo dalla risposta di flusso a quella di trasporto e dalla risposta integrata a quella puntuale. Questo approccio incrementale evidenzia le sfide legate alla validazione della nuova generazione di modelli idrologici integrati quando si guarda a diversi tipi e livelli di dati osservati. Infine, viene eseguita un'analisi conclusiva che si lega a tutti e tre i temi della tesi, descrivendo alcune caratteristiche del modello CATHY_FT, discutendo problemi chiave legati al suo sviluppo futuro e testando il suo compertamento fisico e numerico sia per scenari sintetici che reali. Questo step finale della tesi affronta la miriade di sfide legate alla risoluzione accurata ed efficace del comportamento difficile dell'equazione di avezione-dispersione per processi di trasporto di soluto sotterraneo, alla risoluzione appropriata delle condizioni ai limiti complesse per rappresentare le interazioni di soluto attraverso la superficie terrestre e, in generale, alla rappresentazione delle interazioni tra i fenomeni di flusso e trasporto nell'ambiente superficiale e sotterraneo.
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Lopes, Gabriela Cantarelli. "Desenvolvimento de modelo numerico tridimensional e eliptico para o estudo de escoamentos no interior de dutos cilindricos." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266262.
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Orientador: Jose Roberto NunhezDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Processos que envolvem escoamentos de fluidos no interior de dutos estão presentes em muitas aplicações industriais. Na indústria petroquímica um desses processos que vem se tornando cada vez mais importante é o craqueamento catalítico de frações pesadas do petróleo, já que as converte em frações leves e mais nobres. Por causa da crescente demanda mundial por gasolina e GLP e à sua alta rentabilidade para uma refinaria de petróleo, unidades de craqueamento catalítico em leito fluidizado (FCC) estão presentes em todo o mundo. Testes experimentais costumam ser usados no estudo dos fenômenos envolvidos nesse processo. Porém esse tipo de análise possui alto custo, que pode ser reduzido com o uso de simulações computacionais em seu estudo inicial. Assim, o objetivo deste trabalho foi desenvolver um modelo tridimensional e elíptico, em linguagem Fortran, capaz de fornecer dados para a análise preliminar de escoamentos no interior de reatores de FCC. Na modelagem desses problemas são usadas equações diferenciais parciais, e essas não possuem solução analítica conhecida, sendo necessário o emprego de métodos numéricos para esse fim. Neste trabalho foi usado o Método dos Volumes Finitos, que tem a função de substituir as equações diferenciais parciais por equações algébricas aplicadas a pequenos volumes de controle finitos pertencentes ao domínio. Uma das maiores dificuldades encontradas no tratamento numérico de escoamentos incompressíveis é a determinação de um campo de pressão que satisfaça a Equação da Continuidade. Esse problema foi resolvido fazendo-se uso da abordagem acoplp.da de solução. Para análise do modelo foram obtidos perfis numéricos de velocidade e pressão para fluidos escoando em regimes laminar e turbulento, que foram validados usando-se os dados obtidos com a solução analítica das equações, por correlações (semi-) empíricas ou por dados experimentais, conforme cada um dos casos. Notou-se que o modelo representa muito bem casos laminares, e gue 11.oS casos turbulentos foi necessário um maior refino da malha próximo a parede do tubo. Também foram feitas simulações para que se pudessem observar as características tridimensionais, elípticas e transientes da modelagem do escoamento. De maneira geral o modelo se mostrou bastante rápido, convergindo em poucas iterações. Palavras-Chave: Fluidodinâmica computacional; dutos cilíndricos; modelo tridimensional e elíptico; método dos Volumes Finitos; solução acoplada; turbulência
Abstract: Processes involving fluid flow in tubes are present in many industrial applications. In petrochemical industry one of these processes that are becoming more and more important is the fluid catalytic cracking of heavy petroleum fractions. This fact is due to the process capacity to convert heavy fractions in light and valuable ones. Because of the increasingly worldwide demand for gasoline and LPG and its high yield for a petroleum refinery, fluid catalytic cracking (FCC) units are present in the whole world. Experimental tests are used in the study of the phenomena involved in this processo However this kind of analysis has high cost which can be reduced by using computational simulations in its initial study. Thus, the aim of this work was the development of a three-dimensional and elliptical mo dei in Fortran language in order to provide data for fluid flow preliminary analysis in FCC reactors. Partial differential equations were used in the modeling of these problems. These equations do not have known analytical solution, being necessary therefore the use of numerical methods. In this work the Finite Volume Method were applied with this purpose. This method has as a role to substitute the partial differential equations of the mo dei for algebric equations applied to small finite control volumes of the domain. One of the biggest difficulties found in the numerical treatment of incompressible fluid flows is the determination of apressure field that satisfies the Continuity Equation. This problem was solved using the coupled solution approach. For model analysis, numerical velocity and pressure proJ:iles for laminar and turbulent flows were obtained, that had been validated using the data obtained through the analytical solution of the equations, by empirical correlations or by experimental data, according to each one of the cases. The model represented well laminar cases, and in the turbulent ones the mesh had to be more refined near the tube wall. Other simulations were performed, in aQalyzing the three-dimensional, elliptical and transient model characteristics. In general, the mo dei was very fast, converging in a few interations. Keywords: Computational fluid dyn~mic; cylindrical ducts; three-dimensional and elliptical model; Finite Volume Method; coupled solution; turbulence
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química
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Schultz, Stephen M. "High efficiency volume grating coupler." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16899.
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Zhu, Yan. "Rational design of plastic packaging for alcoholic beverages." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLA020.
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La perception des emballages alimentaires est passée d’utile à source majeure de contaminants dans les aliments et menace pour l’environnement. La substitution du verre par des con-tenants en plastiques recyclés ou biosourcés réduit l’impact environnemental des boissons embouteillées. La thèse a développé de nouveaux outils de simulation 3D et d’optimisation pour accélérer le prototypage des emballages éco-efficaces pour les boissons alcoolisées. La durée de conservation des boissons, la sécurité sanitaire des matériaux plastiques recyclés, les contraintes mécaniques, et la quantité de déchets sont considérées comme un seul problème d'optimisation multicritères. Les nouvelles bouteilles sont générées virtuellement et itérativement en trois étapes comprenant : i) une [E]valuation multiéchelle des transferts de masse couplés ; ii) une étape de [D]écision validant les contraintes techniques (forme, capacité, poids) et réglementaires (durée de conservation, migrations); iii) une étape globale de ré[S]olution recherchant des solutions de Pareto acceptables. La capacité de prédire la durée de vie des liqueurs dans des conditions réelles a été testée avec succès sur environ 500 miniatures en PET (polyéthylène téréphtalate) sur plusieurs mois. L’ensemble de l’approche a été conçu pour gérer tout transfert de matière couplé (perméation, sorption, migration). La sorption mutuelle est prise en compte via une formulation polynaire de Flory-Huggins. Une formulation gros grain de la théorie des volumes libres de Vrentas et Duda a été développée pour prédire les propriétés de diffusion dans les polymères vitreux de l’eau et des solutés organiques dans des polymères arbitraires (polyesters, polyamides, polyvinyles, polyoléfines). 409 diffusivités issues de la littérature ou mesurées ont été utilisée pour validation. La contribution de la relaxation du PET vitreux a été analysée par sorption différentielle (binaire et ternaire) de 25 à 50 °C. Une partie du code source sera partagé afin d'encourager l'intégration de davantage de paramètres affectant la durée de conservation des boissons et des produits alimentaires (cinétique d'oxydation, piégeage d'arômes)The view of plastic food packaging turned from useful to a major source of contaminants in food and an environmental threat. Substituting glass by recycled or biosourced plastic containers reduces environmental impacts for bottled beverages. The thesis developed a 3D computational and optimization framework to accelerate the prototyping of eco-efficient packaging for alcoholic beverages. Shelf-life, food safety, mechanical constraints, and packaging wastes are considered into a single multicriteria optimization problem. New bottles are virtually generated within an iterative three steps process involving: i) a multiresolution [E]valuation of coupled mass transfer; ii) a [D]ecision step validating technical (shape, capacity, weight) and regulatory (shelf-life, migrations) constraints; iii) a global [Solving] step seeking acceptable Pareto solutions. The capacity to predict shelf-life of liquors in real conditions was tested successfully on ca. 500 hundred bottle min iatures in PET (polyethylene terephthalate) over several months. The entire approach has been designed to manage any coupled mass transfer (permeation, sorption, migration). Mutual sorption is considered via polynary Flory-Huggins formulation. A blob formulation of the free-volume theory of Vrentas and Duda was developed to predict the diffusion properties in glassy polymers of water and organic solutes in arbitrary polymers (polyesters, polyamides, polyvinyls, polyolefins). The validation set included 433 experimental diffusivities from literature and measured in this work. The contribution of polymer relaxation in glassy PET was analyzed in binary and ternary differential sorption using a cosorption microbalance from 25 to 50°C. Part of the framework will be released as an open-source project to encourage the integration of more factors affecting the shelf-life of beverages and food products (oxidation kinetics, aroma scalping)
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Taurines, Kevin. "Modelling and experimental analysis of a geothermal ventilated foundation." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI100/document.
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Cette thèse porte sur l’analyse thermique et énergétique d’une fondation géothermique ventilée. A l’instar des échangeurs air-sol classiques (EAHE), celle-ci permet de rafraichir ou préchauffer selon la saison l’air destiné au renouvellement sanitaire des bâtiments. Face aux contraintes de rationalisation des consommations et aux exigences de confort thermique croissantes, ces systèmes passifs apparaissent comme étant prometteurs. Le principe de cette fondation est simple et similaire à celui des EAHE : faire circuler de l’air dans une conduite enterrée dans le sol (un à trois mètres) pour qu’il bénéficie - via convection - de l’inertie thermique du sol. La différence réside dans le fait que le canal dans lequel circule l’air n’est pas un tube en PVC ou aluminium mais fait partie intégrante de la structure du bâtiment, à savoir la fondation en béton armé. Ceci présente comme avantage majeur le gain de place lié à l’espace requis pour l’enfouissement des tuyaux. D’un point de vue thermique, la fondation échange non seulement de la chaleur avec le sol exposé aux sollicitations météorologiques mais aussi, et simultanément, aux sollicitations venant du bâtiment. De plus, la profondeur de la fondation – imposée par des raisons structurelles et économiques – est moindre que pour un EAHE traditionnel. Additionné au fait que le béton est poreux, la présence d’humidité peut fortement influencer la performance thermique de la fondation. Le présent travail propose donc d’étudier le comportement thermique complexe de cette fondation par deux approches. La première est expérimentale : un EHPAD équipé de deux fondations a été lourdement instrumenté et des données ont été accumulées sur plus d’un an. L’autre est numérique : deux modèles validés par comparaison avec les données expérimentales ont été développés. Le premier a vocation d’outil de dimensionnement, l’autre de compréhension fine des phénomènes physiques et prends en compte les transferts couplés de chaleur et de masseThis thesis deals with the thermal and energy analysis of a geothermal ventilated fonudation. Similarly to earth-to-air heat exchangers (EAHE) this foundation enables, according to the season, to preheat or to cool down the air for the hygienic air change. Considering the energy consumption constraints and the buildings users thermal comfort desire, these systems appears to be relevant. The principle of this foundation is simple: to force the air to circulate in a hollowed beam buried into the ground (1 to 3m depth) so that it takes advantage - via convection - to the thermal inertia of the ground. The difference lays on the fact that the channel is not a plastic or aluminium pipe but it a part of the building structure, namely the reinforced concrete foundation. This induces a significant space gain, usually devoted to the pipe burying. From a thermal point of view, the foundation exchanges heat with both the soil beneath the building, and with the soil exposed to the weather thermal loads. Furthermore, the depth - imposed by structural and economical purposees - is lower than that of traditional EAHE. In addition to the fact that concrete is a porous material, the humidity content may strongly influence the thermal performance of the foundation. The current work thus proposes to study the complex thermal behaviour of this foundation in two ways. The first is experimental: an retirement home equipped with two foundation has been intensively instrumented and data recorded over more than one year. The other is numerical: two models validated against the experimental data have been developed. The first is intended to be a designing tool, the second a tool to allow a fine comprehension of the physical phenomenon and take into account coupled heat and moisture transfers
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Mule, Anthony Victor. "Volume grating coupler-based optical interconnect technologies for polylithic gigascale integrat." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/9447.
Full textBooks on the topic "Coupled volumes"
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Linderholt, Andreas, Matthew S. Allen, Randall L. Mayes, and Daniel Rixen, eds. Dynamics of Coupled Structures, Volume 4. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-74654-8.
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Allen, Matt, Randy Mayes, and Daniel Rixen, eds. Dynamics of Coupled Structures, Volume 1. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04501-6.
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Allen, Matt, Randall L. Mayes, and Daniel Rixen, eds. Dynamics of Coupled Structures, Volume 4. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-29763-7.
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Allen, Matthew S., Randall L. Mayes, and Daniel Jean Rixen, eds. Dynamics of Coupled Structures, Volume 4. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-54930-9.
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Allen, Matt, Randall L. Mayes, and Daniel J. Rixen, eds. Dynamics of Coupled Structures, Volume 4. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15209-7.
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Golubitsky, Martin. Pattern Formation in Continuous and Coupled Systems: A Survey Volume. New York, NY: Springer New York, 1999.
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1945-, Golubitsky Martin, Luss Dan 1938-, and Strogatz Steven H, eds. Pattern formation in continuous and coupled systems: A survey volume. New York: Springer, 1999.
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De Neuter, P & Frogneux, Nath. VIOLENCES ET AGRESSIVITES AU SEIN COUPLE - VOLUME 2. Paris: Academia, 2012.
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Felici, Helene M. A coupled Eulerian/Lagrangian method for the solution of three-dimensional vortical flows. Cambridge, Mass: Gas Turbine Laboratory, Massachusetts Institute of Technology, 1992.
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Felici, Helene M. A coupled Eulerian/Lagrangian method for the solution of three-dimensional vortical flows. [Washington, DC: National Aeronautics and Space Administration, 1992.
Find full textBook chapters on the topic "Coupled volumes"
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van Loan, Charles. "A Block QR Factorization Scheme for Loosely Coupled Systems of Array Processors." In The IMA Volumes in Mathematics and Its Applications, 217–32. New York, NY: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4684-6357-6_14.
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Daescu, Dacian, and Gregory R. Carmichael. "Coupled Transport-Chemistry Computations in 4D-Var Data Assimilation for Air Pollution Models." In The IMA Volumes in Mathematics and its Applications, 153–64. New York, NY: Springer New York, 2002. http://dx.doi.org/10.1007/978-1-4757-3474-4_7.
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Clementi, E., D. Logan, and V. Sonnad. "Solution of Large Scale Engineering Problems Using a Loosely Coupled Array of Processors." In The IMA Volumes in Mathematics and Its Applications, 11–27. New York, NY: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4684-6357-6_2.
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Laurent, Karine, Éric Flauraud, Christophe Preux, Quang Huy Tran, and Christophe Berthon. "Design of Coupled Finite Volume Schemes Minimizing the Grid Orientation Effect in Reservoir Simulation." In Finite Volumes for Complex Applications IX - Methods, Theoretical Aspects, Examples, 575–83. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-43651-3_54.
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Eggenweiler, Elissa, and Iryna Rybak. "Interface Conditions for Arbitrary Flows in Coupled Porous-Medium and Free-Flow Systems." In Finite Volumes for Complex Applications IX - Methods, Theoretical Aspects, Examples, 345–53. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-43651-3_31.
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Görtz, Morgan, and Philipp Birken. "On the Convergence Rate of the Dirichlet-Neumann Iteration for Coupled Poisson Problems on Unstructured Grids." In Finite Volumes for Complex Applications IX - Methods, Theoretical Aspects, Examples, 355–63. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-43651-3_32.
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Jacobson, Mark Z. "Development of a Global-Through-Urban Scale Nested and Coupled Air Pollution and Weather Forecast Model and Application to the Sarmap Field Campaign." In The IMA Volumes in Mathematics and its Applications, 277–97. New York, NY: Springer New York, 2002. http://dx.doi.org/10.1007/978-1-4757-3474-4_11.
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Valcke, Sophie, and René Redler. "The OASIS Coupler." In Earth System Modelling - Volume 3, 23–32. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-23360-9_4.
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Gibanica, Mladen, Anders T. Johansson, Anders Liljerehn, Per Sjövall, and Thomas Abrahamsson. "Experimental-Analytical Dynamic Substructuring of Ampair Testbed: A State-Space Approach." In Dynamics of Coupled Structures, Volume 1, 1–14. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04501-6_1.
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Flodén, Ola, Kent Persson, and Göran Sandberg. "Coupling Elements for Substructure Modelling of Lightweight Multi-storey Buildings." In Dynamics of Coupled Structures, Volume 1, 113–24. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04501-6_10.
Full textConference papers on the topic "Coupled volumes"
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Deng, Jack H., Zhangxing Chen, Jia Luo, Kun Wang, and Hui Liu. "Modeling the Stimulated Reservoir Volumes using DPDK Approach Coupled with Rock Mechanics." In 2019 AAPG Annual Convention and Exhibition. Tulsa, OK, USA: American Association of Petroleum Geologists, 2019. http://dx.doi.org/10.1306/42405deng2019.
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Corcoran, Joseph M., and Ricardo A. Burdisso. "An Energy Diffusion Model for Interior Acoustics With Structural Coupling Using the Boundary Element Method." In ASME 2012 Noise Control and Acoustics Division Conference at InterNoise 2012. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ncad2012-0953.
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Recently, a new model for the propagation of sound in interior volumes known as the acoustic diffusion equation has been explored as an alternative method for acoustic predictions and analysis. The model uses statistical methods standard in high frequency room acoustics to compute a spatial distribution of acoustic energy over time as a diffusion process. For volumes coupled through a structural partition, the energy consumed by structural vibration and acoustic energy transmitted between volumes has been incorporated through a simple acoustic transmission coefficient. In this paper, a Boundary Element Method (BEM) solution to the simple diffusion model is developed. The integral form of the 3D acoustic diffusion equation for coupled volumes is derived using the Laplace transform and Green’s Second Identity. The solution using the BEM is developed as well as an efficient Laplace transform inversion scheme to obtain both steady state and transient interior acoustic energy. In addition, a fully coupled model where both structural and acoustic energy are computed as a diffusion process is proposed. A simple volume configuration is examined as the diffusion models are analyzed and compared to conventional room acoustics analysis methods. Advantages of the energy diffusion methods over conventional methods, such as computation of energy distributions and accurate transmission from one volume to another, are revealed as the comparisons are made.
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Watts, C., S. M. Hanham, M. M. Ahmad, M. Adabi, and N. Klein. "Coupled dielectric-split ring microwave resonator for liquid measurements in microfluidic channels at nanoliter volumes." In 2016 46th European Microwave Conference (EuMC). IEEE, 2016. http://dx.doi.org/10.1109/eumc.2016.7824327.
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Panda, Satyajit. "Design and Effective Properties of a Functionally Graded Unidirectional Fiber-Reinforced Composite." In ASME 2015 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/smasis2015-9027.
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The present work deals with the design of a fiber-reinforced composite lamina with varying fiber-volume fraction (FVF) along its thickness direction. In the available elastic analyses of this kind of composite, the elastic properties are evaluated based on the assumptions like continuous variation of FVF and existence of decoupled representative volume element (RVE) at every point along the thickness direction. In order to predict the graded material properties without any of these assumptions at present, first a micro-structure of similar graded composite is designed for the variation of FVF according to a sigmoid function of thickness coordinate. Next, a continuum micro-mechanics finite element model of the corresponding representative volume (RV) is derived. The RV is basically composed of several micro-volumes of different FVFs and the classical homogenization treatment is implemented over these micro-volumes without decoupling them from the overall volume of RV. The importance of this coupled analysis is verified through a parallel decoupled analysis. The effect of the total number of micro-volumes within a specified thickness of lamina on its graded elastic properties is presented. The characteristics of graded elastic properties according to the sigmoid function are also discussed.
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Michopoulos, John G., and Athanasios Iliopoulos. "High Dimensional Full Inverse Characterization of Fractal Volumes." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-71050.
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The present paper describes a methodology for the inverse identification of the complete set of parameters associated with the Weirstrass-Mandelbrot (W-M) function that can describe any fractal scalar field distribution of measured data defined within a volume. Our effort is motivated by the need to be able to describe a scalar field quantity distribution in a volume in order to be able to represent analytically various non-homogeneous material properties distributions for engineering and science applications. Our method involves utilizing a refactoring of the W-M function that permits defining the characterization problem as a high dimensional singular value decomposition problem for the determination of the so-called phases of the function. Coupled with this process is a second level exhaustive search that enables the determination of the density of the frequencies involved in defining the trigonometric functions involved in the definition of the W-M function. Numerical applications of the proposed method on both synthetic and actual volume data, validate the efficiency and the accuracy of the proposed approach. This approach constitutes a radical departure from the traditional fractal dimension characterization studies and opens the road for a very large number of applications and generalizes the approach developed by the authors for fractal surfaces to that of fractal volumes.
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Luizard, Paul, Makoto Otani, Jonathan Botts, Lauri Savioja, and Brian F. Katz. "Comparison of sound field measurements and predictions in coupled volumes between numerical methods and scale model measurements." In ICA 2013 Montreal. ASA, 2013. http://dx.doi.org/10.1121/1.4799138.
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Abrassi, Alessio, Alberto Traverso, David Tucker, and Eric Liese. "Impact of Different Volume Sizes on Dynamic Stability of a Gas Turbine Fuel Cell Hybrid System." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91585.
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Abstract A dynamic model is developed for a Micro Gas Turbine (MGT), characterized by an intrinsic free-spool configuration, coupled to large volumes. This is inspired by an experimental facility at the National Energy Technology Laboratory (NETL) called Hyper, which emulates a hybrid MGT and Fuel Cell system. The experiment and model can simulate stable and unstable operating conditions. The model is used to investigate the effects of different volumes on surge events, and to test possible strategies to safely avoid or recover from unstable compressor working conditions. The modelling approach started from the Greitzer lumped parameter approach, and it has been improved with integration of empirical methods and simulated components to better match the real Hyper plant layout and performance. Pressure, flow rate, and frequency plots are shown for the surge behavior comparing two different volume sizes, for cases where gas turbine shaft speed is uncontrolled (open loop) and controlled (closed loop). The ability to recover from a surge event is also demonstrated.
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Wall, Wolfgang A., Andrew Comerford, Lena Wiechert, and Sophie Rausch. "Coupled and Multi-Scale Building Blocks for a Comprehensive Computational Lung Model." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206407.
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Mechanical ventilation is a vital supportive therapy for critical care patients suffering from Acute Respiratory Distress syndrome (ARDS) or Acute Lung Injury (ALI) in view of oxygen supply. However, a number of associated complications often occur, which are collectively termed ventilator induced lung injuries (VILI) [1]. Biologically, these diseases manifest themselves at the alveolar level and are characterized by inflammation of the lung parenchyma following local overdistension or high shear stresses induced by frequent alveolar recruitment and derecruitment. Despite the more recent adoption of protective ventilation strategies based on the application of lower tidal volumes and a positive end-expiratory pressure (PEEP), patient mortality rates are with approximately 40% still very high. Understanding the reason why the lungs still become damaged or inflamed during mechanical ventilation is a key question sought by the medical community. In this contribution, an overview on recently developed building blocks of a comprehensive lung model will be given, with a main focus on lower airways.
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Xie, Yawei, and Michael G. Edwards. "Higher Resolution Hybrid-Upwind Spectral Finite-Volume Methods, for Flow in Porous and Fractured Media on Unstructured Grids." In SPE Reservoir Simulation Conference. SPE, 2021. http://dx.doi.org/10.2118/203957-ms.
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Abstract A novel higher resolution spectral volume method coupled with a control-volume distributed multi-Point flux approximation (CVD-MPFA) is presented on unstructured triangular grids for subsurface reservoir simulation. The flow equations involve an essentially hyperbolic convection equation coupled with an elliptic pressure equation resulting from Darcy’s law together with mass conservation. The spectral volume (SV) method is a locally conservative, efficient high-order finite volume method for convective flow. In 2D geometry, the triangular cell is subdivided into sub-cells, and the average state variables in the sub-cells are used to reconstruct a high-order polynomial in the triangular cell. The focus here is on an efficient strategy for reconstruction of both a higher resolution approximation of the convective transport flux and Darcy-flux approximation on sub-cell interfaces, which is also coupled with a discrete fracture model. The strategy involves coupling of the SV method and reconstructed CVD-MPFA fluxes at the faces of the spectral volume, to obtain an efficient finer scale higher resolution finite-volume method which solves for both the saturation and pressure. A limiting procedure based on a Barth-Jespersen type limiter is used to prevent non-physical oscillations on unstructured grids. The fine scale saturation/concentration field is then updated via the reconstructed finite volume approximation over the sub-cell control-volumes. Performance comparisons are presented for two phase flow problems on 2D unstructured meshes including fractures. The results demonstrate that the spectral-volume method achieves further enhanced resolution of flow and fronts in addition to that of achieved by the standard higher resolution method over first order upwind, while improving upon efficiency.
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Alhotan, Muhammad, Cunqi Jia, Abdulhamid Alsousy, Mojdeh Delshad, and Kamy Sepehrnoori. "Impact of Permeability Heterogeneity Coupled with Well Placement Strategy on Underground Hydrogen Storage Reservoir Simulation." In Middle East Oil, Gas and Geosciences Show. SPE, 2023. http://dx.doi.org/10.2118/213257-ms.
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Abstract The world is experiencing a transition from traditional to renewable and sustainable clean energy sources. One of the biggest hurdles for this transition is the storage of the excess electricity generated by wind or solar power. Hydrogen has been recognized as a clean-burning fuel that could overcome the barriers to meet this transition. However, there are many challenges associated with hydrogen energy since it requires vast storage volumes. Several new technologies have been proposed to store and produce hydrogen efficiently. One of the most promising storage technologies is Underground Hydrogen Storage (UHS). Reservoir simulation is a critical tool for understanding hydrogen behavior in geological porous media. This study examines the effect of permeability heterogeneity coupled with well placement strategy on several fundamental properties. The simulations are based on a 3D heterogeneous aquifer model with one well as injector/producer. Fifteen-permeability data sets were generated using the Gaussian sequential method using Dykstra-Parson's coefficients (VDP) of 0.3, 0.5, and 0.7, with several realizations. Additionally, the impacts of the well placement strategies in terms of orientations, such as vertical and horizontal configurations, and their locations are investigated. The properties examined are reservoir pressure, hydrogen volume in place and cumulative hydrogen volume recovered. The study uses a real field geological model and a compositional reservoir simulator to conduct these simulations. The published measured hydrogen properties and H2/water relative permeability and capillary pressure curves are incorporated in these simulations. Results indicate that reservoir pressure, the amount of hydrogen in place, and cumulatively produced hydrogen are highly dependent on the heterogeneity of the reservoir and the injection/production well placement. Models with less heterogeneity (i.e., relatively low VDP) show more consistent results on multiple realizations when the well location and orientation are kept constant. On the other hand, high VDP models showed significantly higher variations with different realizations. This paper provides new insights on how to model UHS projects to get the maximum return possible in terms of injected and recovered hydrogen.
Reports on the topic "Coupled volumes"
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Cao Romero, Julio A., Jorge Reyes-Avendaño, Julio Soriano, Leonardo Farfan-Cabrera, and Ali Erdemir. A Pin-on-Disc Study on the Electrified Sliding Wear of EVs Powertrain Gears. SAE International, March 2022. http://dx.doi.org/10.4271/2022-01-0320.
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In contrast to conventional powertrains from internal combustion engine vehicles (ICEV), the tribological performance of powertrains of electric vehicles (EVs) must be further evaluated by considering new critical operating conditions such as electrical environments. The operation of any type of electric motor produces shaft voltages and currents due to various hardware configurations and factors. Furthermore, the common application of inverters intensifies this problem. It has been reported that the induced shaft voltages and currents can cause premature failure problems in tribological components such as bearings and gears due to accelerated wear and/or fatigue. It is ascribed to effects of electric discharge machining (EDM), also named, sparking wear caused by shaft currents and poor or increasingly diminishing dielectric strength of lubricants. A great effort has been done to study this problem in bearings, but it has not yet been the case for gears. Considering that EVs powertrains can be configurated with an electric motor coupled to a single-speed or multi-speed transmission, it is expected that shaft currents can also affect gears to some extent. The pin-on-disc test has been widely used to study sliding wear of gear materials under comparable or realistic operating conditions. This accelerated test is effective for screening materials, lubricants and operating conditions allowing evaluations of their friction and wear properties. However, it has not been implemented for studying gear materials under electrified environments. Thus, this paper aims to explore the friction coefficient and wear of gear materials under non-electrified and electrified sliding in a pin-on-disc tester applying typical of EVs powertrain shaft currents during sliding. The tests were carried out at two different DC currents under comparable gear dry and lubricated sliding contact conditions. Friction coefficient, wear volumes and morphologies were evaluated and reported in this work.
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Levy Yeyati, Eduardo, and Jimena Zúñiga. Varieties of Capital Flows: What Do We Know? Inter-American Development Bank, April 2016. http://dx.doi.org/10.18235/0007017.
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Capital flows have been the subject of acute policy concern since the Brady plan launched the emerging markets bond asset class. Their massive volume, coupled with their volatile and procyclical nature, is often associated with a variety of financial and real risks, which have changed over time. While emerging market crises in the 1990s and 2000s were inherently driven by financial dollarization and balance sheet effects, financial dollarization has receded in emerging markets and the focus has shifted to the macroeconomic effects of cross-market flows, including extended periods of exchange rate misalignment and the amplification of business cycles in a context of large and persistent terms-of-trade shocks and global liquidity swings. These conditions make it difficult to evaluate capital flows based on data mostly from the 1990s and early 2000s, and recent empirical literature is reviewed that revisits the issue with fresh data and an open mind.
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Lacerda Silva, P., G. R. Chalmers, A. M. M. Bustin, and R. M. Bustin. Gas geochemistry and the origins of H2S in the Montney Formation. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329794.
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The geology of the Montney Formation and the geochemistry of its produced fluids, including nonhydrocarbon gases such as hydrogen sulfide were investigated for both Alberta and BC play areas. Key parameters for understanding a complex petroleum system like the Montney play include changes in thickness, depth of burial, mass balance calculations, timing and magnitudes of paleotemperature exposure, as well as kerogen concentration and types to determine the distribution of hydrocarbon composition, H2S concentrations and CO2 concentrations. Results show that there is first-, second- and third- order variations in the maturation patterns that impact the hydrocarbon composition. Isomer ratio calculations for butane and propane, in combination with excess methane estimation from produced fluids, are powerful tools to highlight effects of migration in the hydrocarbon distribution. The present-day distribution of hydrocarbons is a result of fluid mixing between hydrocarbons generated in-situ with shorter-chained hydrocarbons (i.e., methane) migrated from deeper, more mature areas proximal to the deformation front, along structural elements like the Fort St. John Graben, as well as through areas of lithology with higher permeability. The BC Montney play appears to have hydrocarbon composition that reflects a larger contribution from in-situ generation, while the Montney play in Alberta has a higher proportion of its hydrocarbon volumes from migrated hydrocarbons. Hydrogen sulphide is observed to be laterally discontinuous and found in discrete zones or pockets. The locations of higher concentrations of hydrogen sulphide do not align with the sulphate-rich facies of the Charlie Lake Formation but can be seen to underlie areas of higher sulphate ion concentrations in the formation water. There is some alignment between CO2 and H2S, particularly south of Dawson Creek; however, the cross-plot of CO2 and H2S illustrates some deviation away from any correlation and there must be other processes at play (i.e., decomposition of kerogen or carbonate dissolution). The sources of sulphur in the produced H2S were investigated through isotopic analyses coupled with scanning electron microscopy, energy dispersive spectroscopy, and mineralogy by X-ray diffraction. The Montney Formation in BC can contain small discrete amounts of sulphur in the form of anhydrite as shown by XRD and SEM-EDX results. Sulphur isotopic analyses indicate that the most likely source of sulphur is from Triassic rocks, in particular, the Charlie Lake Formation, due to its close proximity, its high concentration of anhydrite (18-42%), and the evidence that dissolved sulphate ions migrated within the groundwater in fractures and transported anhydrite into the Halfway Formation and into the Montney Formation. The isotopic signature shows the sulphur isotopic ratio of the anhydrite in the Montney Formation is in the same range as the sulphur within the H2S gas and is a lighter ratio than what is found in Devonian anhydrite and H2S gas. This integrated study contributes to a better understanding of the hydrocarbon system for enhancing the efficiency of and optimizing the planning of drilling and production operations. Operators in BC should include mapping of the Charlie Lake evaporites and structural elements, three-dimensional seismic and sulphate ion concentrations in the connate water, when planning wells, in order to reduce the risk of encountering unexpected souring.
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Chatagny, Laurent. PR-471-16206-R02 Suction Piping Effect on Pump Performance CFD. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), March 2019. http://dx.doi.org/10.55274/r0011562.
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CFD simulations of pump suction piping coupled to a double suction volute pump were performed with oil at a viscosity of ~90 cSt. Two variants of the suction piping were modeled in order to investigate their effect on the pump performance. Measurement data obtained during PRCI project CPR-15A were used to validate the CFD setup. The CFD results were mostly in line with the measurements, in particular performance and pressure tap values in the suction piping. The pump rotor forces predicted by CFD however showed significant differences to the measured values. The CFD setup presented in this report provides a basis framework for further CFD investigations. This work will benefit the liquids pipeline station designers and operators and also CFD analysts by providing CFD comparisons to benchmark measurements.
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JHA, Anil. Revitalising millets in Northeast India: A healthy choice - Policy Brief. International Centre for Integrated Mountain Development (ICIMOD), December 2023. http://dx.doi.org/10.53055/icimod.1041.
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Millets have long been a staple of the regional diet in Northeast India because of their durability and high nutritional value. However, the rise in consumption of fine cereals, along with a subpar production system and inadequate compensation for millet farmers, have led to the decline of millet consumption and production. The low volume output is exacerbated by the lack of access to good-quality traditional seeds, fertilisers, and effective farming methods, coupled with changing patterns of climate. Furthermore, poor market demand and a lack of pro-poor policies of the government make millet growing even more difficult. Farming communities have few options for generating revenue since limited efforts have been made to market and link millet-based products to markets. Thus, there is a need to support existing farming practices that generate agrobiodiverse landraces, develop climate-resilient cultivars, and facilitate platforms for the value addition of the product. The existing primary processing of millets is labour-intensive and the lack of proper storage facilities results in poor-quality grains fetching low market prices. Thus, there is a need to develop infrastructure and build the capacity of farmers and other stakeholders along the millet value chain.
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Yassin Hassan. Full-Volume, Three-Dimensional, Transient Measurements of Bubbly Flows Using Particle Tracking Velocimetry and Shadow Image Velocimetry Coupled with Pattern Recognition Techniques. Office of Scientific and Technical Information (OSTI), November 2001. http://dx.doi.org/10.2172/791466.
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Gupta, Shikhar, Mehtab Ahmed, Sayema ., Azam Haseen, and Saif Quaiser. Relevance of Preoperative Vessel Mapping and Early Postoperative Ultrasonography in Predicting AV Fistula Failure in Chronic Kidney Disease Patients. Science Repository, February 2024. http://dx.doi.org/10.31487/j.rdi.2023.02.02.
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Introduction: The increasing prevalence of chronic kidney disease (CKD), coupled with advancements in the diagnosis and treatment of renal diseases and improvements in life expectancy, has led to a greater number of patients requiring hemodialysis. The preferred method of vascular access for hemodialysis is AV fistula formation; however, it is associated with a high rate of failure. In our prospective study, we focused on 40 CKD patients planned for initiation of maintenance hemodialysis. Methods: We employed preoperative ultrasound mapping to assess cephalic vein diameter, compressibility, and colour flow, as well as radial and brachial artery diameter, peak systolic velocity, and intimal wall calcification. Postoperatively, ultrasound examinations were conducted on day 7 and at 6 weeks to evaluate fistula blood volume and detect any complications. Results: A significant association between fistula failure and cephalic vein diameter, brachial artery diameter, intimal vessel wall calcification, and comorbid conditions like diabetes mellitus was observed. Furthermore, blood flow at day 7 was notably lower in the failure group compared to those with a functioning fistula and any fistula with blood flow <154 ml/min on day 7 may be predictive of early fistula failure. Conclusion: Preoperative vessel mapping and early postoperative ultrasonography is indispensable for patients who require AV fistula formation for hemodialysis and provide valuable information for selecting suitable vessels for successful fistula creation and enable early intervention to salvage a failing fistula after the surgery. By utilizing these, healthcare professionals can make informed decisions and take necessary steps to optimize the outcomes of AV fistula formation in patients undergoing hemodialysis.
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Markell, Ann, R. C. Goodwin, Susan B. Smith, Ralph Draughon, and Frank Vento. Patterns of Change in Plantation Life in Pointe Coupee Parish, Louisiana: The Americanization of Nina Plantation 1820 - 1890 Volume 2 of 2 Appendices 2 - 10. Fort Belvoir, VA: Defense Technical Information Center, September 1999. http://dx.doi.org/10.21236/ada391102.
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Delwiche, Michael, Boaz Zion, Robert BonDurant, Judith Rishpon, Ephraim Maltz, and Miriam Rosenberg. Biosensors for On-Line Measurement of Reproductive Hormones and Milk Proteins to Improve Dairy Herd Management. United States Department of Agriculture, February 2001. http://dx.doi.org/10.32747/2001.7573998.bard.
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The original objectives of this research project were to: (1) develop immunoassays, photometric sensors, and electrochemical sensors for real-time measurement of progesterone and estradiol in milk, (2) develop biosensors for measurement of caseins in milk, and (3) integrate and adapt these sensor technologies to create an automated electronic sensing system for operation in dairy parlors during milking. The overall direction of research was not changed, although the work was expanded to include other milk components such as urea and lactose. A second generation biosensor for on-line measurement of bovine progesterone was designed and tested. Anti-progesterone antibody was coated on small disks of nitrocellulose membrane, which were inserted in the reaction chamber prior to testing, and a real-time assay was developed. The biosensor was designed using micropumps and valves under computer control, and assayed fluid volumes on the order of 1 ml. An automated sampler was designed to draw a test volume of milk from the long milk tube using a 4-way pinch valve. The system could execute a measurement cycle in about 10 min. Progesterone could be measured at concentrations low enough to distinguish luteal-phase from follicular-phase cows. The potential of the sensor to detect actual ovulatory events was compared with standard methods of estrus detection, including human observation and an activity monitor. The biosensor correctly identified all ovulatory events during its testperiod, but the variability at low progesterone concentrations triggered some false positives. Direct on-line measurement and intelligent interpretation of reproductive hormone profiles offers the potential for substantial improvement in reproductive management. A simple potentiometric method for measurement of milk protein was developed and tested. The method was based on the fact that proteins bind iodine. When proteins are added to a solution of the redox couple iodine/iodide (I-I2), the concentration of free iodine is changed and, as a consequence, the potential between two electrodes immersed in the solution is changed. The method worked well with analytical casein solutions and accurately measured concentrations of analytical caseins added to fresh milk. When tested with actual milk samples, the correlation between the sensor readings and the reference lab results (of both total proteins and casein content) was inferior to that of analytical casein. A number of different technologies were explored for the analysis of milk urea, and a manometric technique was selected for the final design. In the new sensor, urea in the sample was hydrolyzed to ammonium and carbonate by the enzyme urease, and subsequent shaking of the sample with citric acid in a sealed cell allowed urea to be estimated as a change in partial pressure of carbon dioxide. The pressure change in the cell was measured with a miniature piezoresistive pressure sensor, and effects of background dissolved gases and vapor pressures were corrected for by repeating the measurement of pressure developed in the sample without the addition of urease. Results were accurate in the physiological range of milk, the assay was faster than the typical milking period, and no toxic reagents were required. A sampling device was designed and built to passively draw milk from the long milk tube in the parlor. An electrochemical sensor for lactose was developed starting with a three-cascaded-enzyme sensor, evolving into two enzymes and CO2[Fe (CN)6] as a mediator, and then into a microflow injection system using poly-osmium modified screen-printed electrodes. The sensor was designed to serve multiple milking positions, using a manifold valve, a sampling valve, and two pumps. Disposable screen-printed electrodes with enzymatic membranes were used. The sensor was optimized for electrode coating components, flow rate, pH, and sample size, and the results correlated well (r2= 0.967) with known lactose concentrations.
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Markell, Ann, R. C. Goodwin, Susan B. Smith, Ralph Draughon, and Frank Vento. Patterns of Change in Plantation Life in Pointe Coupee Parish, Louisana: The Americanization of Nina Plantation, 1820 - 1890 Volume 1 of 2 Chapters 1 - 10 and Appendix 1. Fort Belvoir, VA: Defense Technical Information Center, September 1999. http://dx.doi.org/10.21236/ada390996.
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