Littérature scientifique sur le sujet « Double-ring »

The token ring has several advantages over other networks, especially under a heavy load. However, Bux and Grillo showed that all desirable characteristics of IEEE 802.2 and 802.5 protocols for a single token ring are severely degraded in an interconnected token ring network. In order to address the problem, Bux and Grillo suggested a method of dynamically adjusting the size of windows depending on the traffic of a network. In this thesis, a different method of addressing the problem was proposed. The proposed method is to add a secondary transmission link to the backbone ring of a network to form a double linked backbone ring network. Simulation results show that the most influential element contributing to the degradation of performance is congestion at the bridges in a network. The processing speed of bridges for the proposed double linked backbone ring network is essentially double that of the original network. The increased processing speed of the bridges enhances the performance of the network. Experimental results for the utilization, throughput and response time of the original network and the proposed double linked backbone ring are presented:
Master of Science

Sergei Koussevitzky was one of the world’s premier conductors and virtuoso bass players whose favorite instrument was an unusually-shaped bass reportedly made in 1611 by the Amati brothers, Antonio and Girolamo. In 1962, 11 years after Koussevitzky’s death, his widow gave the bass to Gary Karr, currently considered to be the world’s premier double bassist. In 2004, Karr donated the bass to the International Society of Bassists. Close inspection by a team of experts in 2004, however, revealed stylistic inconsistencies that suggested a later construction date. We used four reference tree-ring chronologies developed from treeline species in the European Alpine region to anchor the dates for the tree rings from the double bass absolutely in time. The bass yielded a 317-year long sequence, the longest sequence yet developed from a single musical instrument. Statistical and graphical comparisons revealed that the bass has tree rings that date from 1445 to 1761. Based on the strength of these correlations, the spruce tree harvested to eventually construct the double bass likely came from the treeline Alpine area of western Austria, not too far from Obergurgl at the Italian border. Our results demonstrate that the double bass was not made by the Amati Brothers, but likely by French luthiers in the late 18th Century.

A nanoscale Aharonov-Bohm (AB) ring with a quantum dot (QD) embedded in each arm is investigated analytically to provide electron transmission characteristics. A parallel magnetic field provides Zeeman splitting of the QD energy levels. Combined Zeeman energy level splitting and AB-effects occur with a perpendicular field. In our device, the AB-ring interferometer, Zeeman splitting of the QD energy levels creates regions of parameter space in which the electron transmission is highly spin-polarized. In addition to Zeeman splitting caused by a parallel magnetic field, combined Zeeman energy level splitting and AB-interference effects occur with a perpendicular field. The weighted spin-polarization function is calculated and presented as a function of magnetic field and electron energy. Due to a unique parameter regime in which the AB-oscillations show extreme sharpening [1], the electron transmission can be tuned to produce spin-polarized currents which can be switched and controlled by small changes of external fields.
Introduction -- AB-oscillations and resonances in a double quantum dot ring -- Results for combined Zeeman and AB effects -- Spin-polarization.
Department of Physics and Astronomy

A sealed double ring infiltrometer (SDRI) was used at Page Ranch, Arizona to measure saturated hydraulic conductivity (Ksat in a test clay pad, as well as to characterize preferential flow and transport mechanisms. Ksat varied from 3.5 x 10⁻⁹ to 2.2 x 10⁻¹⁰ cm/sec depending on treatment of matric potential at the wetting front. These in-situ Ksat values were about one order of magnitude less than the laboratory values that ranged from 10⁻⁷ to 10⁻⁹ cm/sec. Although the pad was not instrumented to detect a shallow wetting front, the dye front and water content data indicated that flow penetrated 4 to 6 cm by the end of the 75 day test. Tracer data suggested that bromide moved to 18 or 20 cm by diffusion and that the effective diffusion coefficient was 15 to 21 x 10⁻¹⁰ m²sec. Preferential flow, as judged by the uniformity of the dye front and bromide tracer movement, was insignificant.

Quilts can be blankets that keep you warm at night. They can be several pieces of fabric that are purposefully sewn together to make a beautiful, meaningful pattern. Quilts can be gifts. They can be pieces of artwork that someone has poured their heart into. Over time, quilts can become more meaningful to their owners. They can become a memory of their maker. I hope that the quilts I have made in the last year live on and become more meaningful in time. They are an expression of a young woman in 2017 and her quarrels with tradition.

In this study, a two phase investigation of the hydraulic conductivity parameters of silty soils was performed. In the first phase, double-ring infiltrometer tests were used to measure infiltration rates in-situ at two sites in the Piedmont physiographic province of Georgia. The efficacy of predicting saturated hydraulic conductivity for Piedmont soils via published soil surveys from the National Resource Conservation Service and pedotransfer functions was then investigated. Work focused on the development of a consistent test methodology for soils (sandy, to silts and clays) in the Piedmont, and the final test method utilized being the constant head test, using a double-ring infiltrometer with Mariotte tubes to maintain the head. In the second phase of the investigation, laboratory based measurements of the saturated hydraulic conductivity of binary mixtures of fine sand and nonplastic silt were performed to investigate the effects of particle mixtures on hydraulic conductivity. The materials used were ASTM 100/200 sand and Sil-Co-Sil 40 non-plastic silt, chosen based on the ratio of the mean particle diameters. Significant effort was invested in the development and comparison of methodologies to produce uniform specimens of the binary mixtures for hydraulic conductivity testing, with the final being modified dry tubing. Two fixed densities were used to investigate the effects of particle packing on the hydraulic conductivity of binary mixtures, with critical fines contents chosen to ensure the finer particles primarily filled the pore volume of the coarse particles. Incremental fines contents, by mass, up to this theoretical fines content were tested. The measured saturated hydraulic conductivity was evaluated in terms of fines content, global and intergranular void ratio, and confining stress. Models for predicting extreme void ratios and saturated hydraulic conductivity of binary mixtures were also investigated.

Los modelos numéricos son herramientas fundamentales para realizar predicciones de muchos problemas enfrentados por ingenieros geotécnicos y geoambientales. Sin embargo, para que estos modelos puedan realizar predicciones confiables, los parámetros de entrada del modelo deben ser estimados considerando el efecto escala. En este contexto, esta tesis se concentra en las reglas del cambio de escala de los parámetros de flujo y transporte de masa en un suelo tropical a través de estudios numéricos, de laboratorio y de campo. Esta está organizada en cuatro partes. Primero, la heterogeneidad, correlación y correlación cruzada entre los parámetros de transporte de solutos (dispersividad, ¿, y coeficiente de partición, Kd) y las propiedades del suelo fueron estudiadas en detalle. En esta parte fue verificado que la conductividad hidráulica (K) y los parámetros de transporte de solutos son altamente heterogéneos, mientras que las propiedades del suelo no lo son. La correlación espacial de ¿ y K con variables estadísticamente significativas fue estudiada. Este resultado probablemente podrá mejorar la estimación en casos de estudios de pequeña escala debido a que solo fue observada correlaciones de hasta 2,5 m. Este estudio fue un primer intento de evaluar la variación espacial en el coeficiente de correlación de los parámetros de transporte de un soluto reactivo y de un no reactivo, indicando las variables más relevantes y aquella que debería ser incluida en estudios futuros. En la segunda parte, el efecto escala en K, dispersividad y coeficiente de partición de potasio y clorito fue estudiado experimentalmente a través de experimentos de laboratorio y de campo. El objetivo de esta parte fue contribuir a la discusión sobre el efecto escala en K, ¿ y Kd, y entender como estos parámetros se comportan con el cambio de escala de medición. La dispersividad tiende a aumentar con la altura de la muestra de manera exponencial. El coeficiente de partición tiende a aumentar con la altura, el diámetro y el volumen de la muestra. Estas diferencias encontradas en los parámetros de acuerdo con la escala de medición deben ser considerados cuando estos valores sean usados posteriormente como datos de entrada de modelos numéricos; de otra manera, las respuestas pueden ser malinterpretadas. Tercero, análisis estocásticos tridimensionales de cambio de escala de la conductividad hidráulica fueron realizados usando los métodos de promedios simples y de Laplace con piel para una variedad de tamaños de bloques usando mediciones reales de K. En esta parte son demostrados los errores que pueden ser introducidos al usar métodos determinísticos de cambio de escala usando promedios simples de las mediciones de K sin llevar en consideración la correlación espacial. La aplicación muestra que la heterogeneidad de K puede ser incorporada en la práctica diaria del modelador geotécnico. Los aspectos que considerar durante un proceso de cambio de escala también son discutidos. Finalmente, la dependencia del exponente de la norma-p como función del tamaño del bloque fue analizada. En la última parte, una aplicación de cambio de escala estocástico del coeficiente de dispersión hidrodinámica D y del factor de retardo R fue realizada usando datos reales con el objetivo de reducir la falta de casos de investigación experimental de cambio de escala de parámetros de transporte de solutos reactivos. El cambio de escala de D fue realizado usando el método de macrodispersión. El método de promedio simple de norma-p fue usado para realizar el cambio de escala de R. Una buena propagación de incertidumbres fue alcanzada. Métodos simples de cambio de escala pueden ser introducidos en la práctica del modelaje usando programas comerciales de transporte y conseguir reproducir el transporte en escala gruesa, pero puede requerir correcciones con el objetivo de reducir el efecto de suavizado de la heterogeneidad causado por el
Numerical models are becoming fundamental tools to predict a range of complex problems faced by geotechnical and geo-environmental engineers. However, to render the model reliable for future predictions, the model input parameters must be determined with consideration of the scale effects. In this context, this thesis focuses on upscaling of water flow and mass transport in a tropical soil by means of numerical, laboratory and field studies. This thesis is organized in four parts. First, the heterogeneity, correlation and cross-correlation between solute transport parameters (dispersivity, ¿, and partition coefficient, Kd) and soil properties were studied in detail. In this part, it was verified that the hydraulic conductivity (K) and solute transport parameters are highly heterogeneous, while soil properties not. Spatial correlation of ¿, K, and statistically significant variables were studied, and it would probably improve the estimation only in a small-scale study, since the spatial correlation were only observed up to 2.5 m. This study was a first attempt to evaluate the spatial variation in the correlation coefficient of transport parameters of a reactive and a nonreactive solute, indicating the more relevant variables and the one that should be included in future studies. In the second part, scale effect on K, dispersivity and partition coefficient of potassium and chloride is studied experimentally by means of laboratory and field experiments. The purpose of was to contribute to the discussion about scale effects on K, ¿ and Kd and understanding how these parameters behave with the change in the scale of measurement. Results shows that K increases with scale, regardless of the method of measurement. Dispersivity trends to increases exponentially with the sample height. Partition coefficient, tend to increase with sample length, diameter and volume. These differences in the parameters according to the scale of measurement must be considered when these observations are later used as input to numerical models, otherwise the responses can be misrepresented. Third, stochastic analysis of three-dimensional hydraulic conductivity upscaling was performed using a simple average and the Laplacian-with-skin methods for a variety of block sizes using real K measurements. In this part it was demonstrated the errors that can be introduced by using a deterministic upscaling using simple averages of the measured K without accounting for the spatial correlation. The application shows that K heterogeneity can be incorporated in the daily practice of the geotechnical modeler. The aspects to consider when performing the upscaling were also discussed. Finally, the dependence of the exponent of the p-norm as a function of the block size was analyzed. In the last part, an application of stochastic upscaling of hydrodynamic dispersion coefficient (D) and retardation factor (R) was performed using real data aiming to reduce the lack in experimental upscaling of reactive solute transport research. Upscaling of D was done using macrodispersion method. Simple average method based on p-norm was used to perform R upscaling. A good propagation of the uncertainties was achieved. Simple upscaling methods can be incorporated to the modeling practice using commercial transport codes and properly reproduce de transport at coarse scale but may require corrections to reduce smoothing of the heterogeneity caused by the upscaling procedure.
Els models numèrics s'estan constituint en eines fonamentals per a realitzar prediccions d'una àmplia gamma de problemes enfrontats per enginyers geotècnics i geoambientales. No obstant açò, perquè aquests models puguen realitzar prediccions fiables, els paràmetres d'entrada del model han de considerar l'efecte escala. En aquest context, aquesta tesi es concentra en les regles del canvi d'escala dels paràmetres de flux i transport de massa en un sòl tropical a través d'estudis numèrics, de laboratori i de camp. Aquesta tesi està organitzada en quatre parts. Primer, l'heterogeneïtat, correlació i correlació creuada entre els paràmetres de transport de soluts (dispersivitat, ¿, i coeficient de partició, Kd) i les propietats del sòl van ser estudiades detalladament. En aquesta part va ser verificat que la conductivitat hidràulica (K) i els paràmetres de transport de soluts són altament heterogenis, mentre que les propietats del sòl no ho són. La correlació espacial de ¿ i K amb variables estadísticament significatives va ser estudiada. Aquest resultat probablement podrà millorar l'estimació en casos d'estudis de xicoteta escala a causa que solament va ser observada correlacions de fins a 2,5 m. Aquest estudi va ser un primer intent d'avaluar la variació espacial en el coeficient de correlació dels paràmetres de transport d'un solut reactiu i d'un no reactiu, indicant les variables més rellevants i aquelles que haurien de ser inclosas en estudis futurs. En la segona part, l'efecte escala en K, dispersivitat i coeficient de partició de potassi i clorito va ser estudiat experimentalment a través d'experiments de laboratori i de camp. L'objectiu d'aquesta part va ser contribuir a la discussió sobre l'efecte escala en K, ¿ i Kd, i entendre com aquests paràmetres es comporten amb el canvi d'escala de mesurament. La dispersivitat tendeix a augmentar amb l'altura de la mostra, és a dir, amb la longitud del transport, de manera exponencial. El coeficient de partició tendeix a augmentar amb l'altura, el diàmetre i el volum de la mostra. Aquestes diferències en els paràmetres d'acord amb l'escala de mesurament han de ser considerats quan aquests valors siguen usats posteriorment com a dades d'entrada de models numèrics; d'una altra manera, les respostes poden ser malament interpretades. Tercer, anàlisis estocàstiques tridimensionals de canvi d'escala de la conductivitat hidràulica van ser realitzats usant els mètodes de mitjanes simples i de Laplace amb pell per a una varietat de grandàries de blocs usant mesuraments reals de K. En aquesta part són demostrats els errors que poden ser introduïts en usar mètodes determinístics de canvi d'escala usant mitjanes simples dels mesuraments de K sense tindre en consideració la correlació espacial. L'aplicació mostra que l'heterogeneïtat de K pot ser incorporada en la pràctica diària del modelador geotècnic. Els aspectes a considerar durant un procés de canvi d'escala també són discutits. Finalment, la dependència de l'exponent de la norma-p com a funció de la grandària del bloc va ser analitzada. En l'última part, una aplicació de canvi d'escala estocàstic del coeficient de dispersió hidrodinámica D i del factor de retard R va ser realitzada usant dades reals amb l'objectiu de reduir la falta de casos de recerca experimental de canvi d'escala de paràmetres de transport de soluts reactius. El canvi d'escala de D va ser realitzat usant el mètode de macrodispersió. El mètode de mitjana simple de norma-p va ser usat per a realitzar el canvi d'escala de R. Una bona propagació d'incerteses va ser aconseguida. Mètodes simples de canvi d'escala poden ser introduïts en la pràctica de la modelació usant programes comercials de transport i aconseguir reproduir el transport en escala gruixuda, però pot requerir correccions amb l'objectiu de reduir l'efecte de suavitzat de l'heterogeneïtat causat pel procés de canvi d'escala.
Almeida De Godoy, V. (2018). Upscaling of water flow and mass transport in a tropical soil: numerical, laboratory and field studies [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/102405
TESIS

Este trabalho tem como objetivo o estudo dos coeficientes de atrito obtidos através do ensaio do anel, que é um dos métodos clássicos para verificação e a caracterização do atrito, comparado com a extrusão por duplo copo, DCE (Double Cup Extrusion). Foram feitos ensaios utilizando como material para confecção dos corpos de prova o alumínio AA6351 e variando três situações de lubrificação: teflon, grafite e ensaios sem lubrificação. Para o DCE foi desenvolvido o projeto e fabricação do ferramental, permitindo variar punções de duas dimensões diferentes. Os resultados obtidos nos experimentos com cada uma das técnicas foram comparados e apresentados, traçando-se um paralelo do atrito verificado, bem como o comportamento do material em relação às ferramentas utilizadas nos experimentos e as variações de lubrificação.
This work aims to study the friction coefficients obtained by the ring test, which is one of the classic methods for verification and characterization of friction, compared with DCE (Double Cup Extrusion). The tests were made using as material for preparation of specimens, the aluminum AA6351 and varying three situations lubrication, Teflon, graphite and tests without lubrication. For DCE was developed the design and manufacture of tooling, allowing vary punctures in two differ dimensions. The results obtained in the experiments with each of the techniques have been compared and shown by drawing a parallel scanned the friction and the material behavior in relation to the tools used in the experiments and lubrication changes.

Optical bistability in double-ring cavities, in which a ring cavity containing a nonlinear medium is nested within another ring cavity, has been considered and has been shown to exhibit frustrated instabilities,1 multistability,2 and threshold and response time reduced relative to a single-ring cavity.3