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Tracer experiments for dispersion modelling in river Douro water quality management

Duarte, António A. L. Sampaio; Pinho, José L. S.; Vieira, J. M. Pereira; Boaventura, Rui A. Rocha
Fonte: IWA Publicador: IWA
Tipo: Conferência ou Objeto de Conferência
Publicado em /07/2000 ENG
Relevância na Pesquisa
36.853071%
Parameters estimation for in situ dispersion river water behaviour characterisation, and performance evaluation of numerical models, applied to reproduce data field obtained from dye tracer experiments, were the main purposes of this research work. A monitoring program was carried out using tracer injection to assess the environmental impact of accidental pollutant discharges in an international reach of river Douro, between Castro dam (Spain) and Miranda dam (Portugal). This paper presents the methodology used in the tracer experiments, the concentration-time curves, describing dye tracer spread, the results of different simulation and their agreement with the measured data, and peak attenuation with dye spread travel time. Longitudinal dispersion coefficients values are estimated according to the river hydrodynamics.

U-TRACER: uma ferramenta de visualização da informação sobre o uso das Tecnologias da Comunicação no Ensino Superior Público Português

Pinto, Marta; Raposo, Rui; Ramos, Fernando
Fonte: Universidade de Aveiro/CIDTFF Publicador: Universidade de Aveiro/CIDTFF
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
27.07707%
U-TRACER é uma ferramenta que tem como objetivo dar visibilidade aos dados recolhidos no projeto TRACER, dados que dizem respeito ao uso das Tecnologias da Comunicação nas Instituições de Ensino Superior Público Português. Os dados foram recolhidos junto das instituições através de um questionário online. A divulgação dos dados é feita através da U-TRACER que adota soluções de visualização de informação, permitindo a interação com filtros de informação para a geração de gráficos de acordo com os interesses do utilizador. A ferramenta é composta por duas áreas principais, o Backoffice (BO) que serve para recolha dos dados, e a área do Frontoffice (FO) que dá visibilidade aos dados recolhidos em BO. A conceptualização do FO foi feita em conjunto com profissionais do ensino superior através de sessões de focus group, testes à eficácia de leitura dos gráficos e testes de usabilidade ao protótipo. Destes testes resultaram a proposta de interação através de filtros de informação e representação gráfica a adotar, incluindo recomendações de melhoria ao BO e FO. Os participantes que testaram a U-TRACER indicaram estar globalmente satisfeitos. Contudo, as melhorias sugeridas estão a ser implementadas. O número limitado de ferramentas de visualização de informações sobre os dados que representam instituições de ensino superior justifica o interesse da U-TRACER que vem juntar-se a outros projetos pioneiros U-MAP e U-Multirank...

Validação e avaliação da plataforma U-TRACER

Pinto, Marta; Raposo, Rui; Ramos, Fernando
Fonte: UA Editora Publicador: UA Editora
Tipo: Parte de Livro
POR
Relevância na Pesquisa
36.853071%
A avaliação e validação da plataforma U-TRACER® envolveram dois momentos de recolha de dados junto de participantes. A avaliação ao BO e FO da plataforma envolveu a realização de um teste de usabilidade por sete utilizadores finais. A eficácia e eficiência das tarefas executadas resultaram num conjunto alargado de propostas de melhorias a implementar na plataforma, e das quais cerca de metade foram posteriormente implementadas na versão final. Globalmente, o uso da plataforma foi categorizado como satisfatório pelos participantes do teste de usabilidade. A validação da U-TRACER® adotou uma outra metodologia, que consistiu em realizar entrevistas aos decisores institucionais, que providenciaram dados ao projeto TRACER sobre o uso das TC na perspetiva institucional, dados que alimentam a plataforma U-TRACER®. Através das entrevistas foi possível perceber quais as principais utilidades que estes decisores prevêem para a plataforma, as suas vantagens e algumas preocupações.

U-TRACER®: Uma Plataforma de Registo e Partilha de Informação sobre o Uso das Tecnologias da Comunicação no Ensino Superior; U-TRACER®: A Platform for recording and sharing information on the use of communication technologies in Higher Education

Ramos, Fernando; Pinto, Marta; Raposo, Rui; Pedro, Luís; Almeida, Pedro
Fonte: EDUCOM-APTE Publicador: EDUCOM-APTE
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
37.021533%
Este artigo apresenta a plataforma U-TRACER®, desenvolvida no âmbito do projeto TRACER-Uso das Tecnologias de Comunicação no Ensino Superior Público Português, realizado no período de 2011-2014 envolvendo uma equipa de investigação multidisciplinar das áreas de Educação e de Ciências e Tecnologias da Comunicação. A plataforma U-TRACER® foi concebida e desenvolvida com o objetivo de permitir recolher, sistematizar e disponibilizar, utilizando técnicas de visualização de informação, dados sobre a utilização de Tecnologias da Comunicação no Ensino Superior público Português, considerada relevante para decisores, docentes, investigadores e estudantes. A plataforma permite a visualização de dados relativos a uma instituição de Ensino Superior específica ou a um conjunto de instituições, com base em critérios institucionais, geográficos, temporais e temáticos. O artigo descreve a organização e as principais funcionalidades da plataforma U-TRACER®, os principais resultados da validação realizada e apresenta, ainda, algumas considerações finais relacionadas com a sustentabilidade da plataforma.; This paper presents the U-TRACER® platform developed under the TRACER project (Use of Communication Technologies in the Portuguese Public Higher Education)...

U-TRACER® - the use of communication technology in higher education - an information visualization tool for the context of Portuguese public higher education; U-TRACER® - o uso das tecnologias da comunicação no ensino superior - uma ferramenta de visualização de informação para o contexto do ensino superior público português

Carvalho, Marta Pinto de
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
27.091587%
Information Visualization is gradually emerging to assist the representation and comprehension of large datasets about Higher Education Institutions, making the data more easily understood. The importance of gaining insights and knowledge regarding higher education institutions is little disputed. Within this knowledge, the emerging and urging area in need of a systematic understanding is the use of communication technologies, area that is having a transformative impact on educational practices worldwide. This study focused on the need to visually represent a dataset about how Portuguese Public Higher Education Institutions are using Communication Technologies as a support to teaching and learning processes. Project TRACER identified this need, regarding the Portuguese public higher education context, and carried out a national data collection. This study was developed within project TRACER, and worked with the dataset collected in order to conceptualize an information visualization tool U-TRACER®. The main goals of this study related to: conceptualization of the information visualization tool U-TRACER®, to represent the data collected by project TRACER; understand higher education decision makers perception of usefulness regarding the tool. The goals allowed us to contextualize the phenomenon of information visualization tools regarding higher education data...

Dynamic evaluation for liquid tracer in a trickle bed reactor

Silva,J. D.
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2011 EN
Relevância na Pesquisa
36.588347%
A mathematical model is developed for a liquid flow on solid particles in a trickle bed reactor. A mathematical formulation is followed based on the liquid-solid model approach where the liquid phase with the (KCl) tracer is treated as a continuum. The physical modeling is discussed, including the formulation of initial and boundary conditions and the description of the solution methodology. Results of mathematical model are presented and validated. The model is validated through comparison using three experimental cases. The optimized values of the axial dispersion (Dax), liquid-solid mass transfer (kLS), and partial wetting efficiency (F M) coefficients are obtained simultaneously using the objective function. The behavior of Dax, kLS, and F M is analyzed by the empirical correlations.

Single-scan dual-tracer FLT+FDG PET tumor characterization

Kadrmas, Dan J; Rust, Thomas C; Hoffman, John M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.103486%
Rapid multi-tracer PET aims to image two or more tracers in a single scan, simultaneously characterizing multiple aspects of physiology and function without the need for repeat imaging visits. Using dynamic imaging with staggered injections, constraints on the kinetic behavior of each tracer are applied to recover individual-tracer measures from the multi-tracer PET signal. The ability to rapidly and reliably image both 18F-fluorodeoxyglucose (FDG) and 18F-fluorothymidine (FLT) would provide complementary measures of tumor metabolism and proliferative activity, with important applications in guiding oncologic treatment decisions and assessing response. However, this tracer combination presents one of the most challenging dual-tracer signal-separation problems—both tracers have the same radioactive half-life, and the injection delay is short relative to the half-life and tracer kinetics. This work investigates techniques for single-scan dual-tracer FLT+FDG PET tumor imaging, characterizing the performance of recovering static and dynamic imaging measures for each tracer from dual-tracer datasets. Simulation studies were performed to characterize dual-tracer signal-separation performance for imaging protocols with both injection orders and injection delays of 10–60 min. Better performance was observed when FLT was administered first...

A new method for determining the conversion of low-ash coals using synthetic ash as a tracer

Ballantyne, T.; Ashman, P.; Mullinger, P.
Fonte: Elsevier Sci Ltd Publicador: Elsevier Sci Ltd
Tipo: Artigo de Revista Científica
Publicado em //2005 EN
Relevância na Pesquisa
36.588347%
Victorian brown coal represents a significant resource for power generation in Australia. The typical ash content for these coals can be as low as 1% (dry basis). While low ash content is obviously a major advantage for the utilisation of these coals, it is a problem for researchers in that the low ash content leads to large inaccuracies when using the ‘ash tracer’ method to determine coal conversion in flow reactors. To address this problem, a modified ash tracer method has been developed to determine coal conversion which involves adding perlite as an artificial ash to the coal. This method has been successfully applied to measure coal conversion during the pyrolysis of Loy Yang coal in a drop tube furnace.; http://www.elsevier.com/wps/find/journaldescription.cws_home/30420/description#description; Timothy R. Ballantyne, Peter J. Ashman, Peter J. Mullinger

Model comparisons for tracer experiments at a clear water storage tank

Crowther, J.; Dandy, G.
Fonte: Institution of Engineers Australia Publicador: Institution of Engineers Australia
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
36.710527%
A fluoride tracer experiment was conducted to investigate mixing processes and residence times in a cylindrical clear water storage tank at the Stromlo Water Treatment Plant, Canberra, ACT. Four different modelling techniques have been used to simulate the experimental results: computational fluid dynamics (CFD), a single continuously stirred tank reactor (CSTR), two CSTRs in series, and a series/parallel combination of two CSTRs (NM). Flow of a conservative tracer through the tank has been simulated at the rated flow from the works using the PHOENICS (CFD) program. The CFD simulation agrees closely with the measured fluoride concentrations and requires no fitted parameters. The agreement with the experimental data for NM is comparable with the CFD and a little better than two CSTRs in series. The poorest agreement was obtained with a single CSTR model.; JM Crowther, GC Dandy

Characterization of complex non-aqueous phase liquids (NAPLs) in the subsurface environment: partitioning and interfacial tracer tests and numerical dissolution assessment; Charakterisierung von komplexen, mit Wasser nicht mischbaren Flüssigkeiten im Untergrund: Verteilungs- and Grenzflächen-Tracertests und numerische Einschätzung der Lösungsprozesse

Piepenbrink, Matthias
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
37.05897%
Contamination of the subsurface environment by complex organic non-aqueous phase liquids (NAPLs) and the resulting release of carcinogenic or mutagenic organic compounds impose a serious risk on groundwater quality. Due to the low aqueous solubilities of the individual organic components the rate of mass transfer from the non-aqueous phase to the water phase is very slow, thus NAPL source zones typically represent long-term contamination problems with organic compounds leaching into the ground water, at aqueous concentrations still far in excess of drinking water standards, for decades or centuries until they are finally depleted. Characterizing, understanding and predicting the behaviour of complex multi-component NAPLs at such contaminated sites is given primary attention in site assessment and site remediation. However, up to now even the determination of essential NAPL source zone parameters such as spatial NAPL distribution, NAPL saturation (Sn) and especially NAPL distribution geometry is difficult; conventional invasive methods like soil coring are costly and give only point-scale measurements. Within this thesis, a numerical model for multi-component NAPL dissolution in porous media (BIONAPL/3D) was used for numerical NAPL dissolution assessment and to gain further insight into interactions between dissolved...

Transverse relaxation in sandstones due to the effect of internal field gradients and characterizing the pore structure of vuggy carbonates using NMR and Tracer analysis

Rohilla, Neeraj
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
36.793296%
Nuclear magnetic resonance (NMR) has become an indispensable tool in petroleum industry for formation evaluation. This dissertation addresses two problems. • We aim at developing a theory to better understand the phenomena of transverse relaxation in the presence of internal field gradients. • Chracterizing the pore structure of vuggy carbonates. We have developed a two dimensional model to study a system of claylined pore. We have identified three distinct relaxation regimes. The interplay of three time parameters characterize the transverse relaxation in three different regimes. In future work, useful geometric information can be extracted from from SEM images and the pore size distribution analysis of North Burbank sandstone to simulate transverse relaxation using our 2-D clay flake model and study diffusional coupling in the presence of internal field gradients. Carbonates reservoirs exhibit complex pore structure with micropores and macropores/vugs. Vuggy pore space can be divided into separate-vugs and touching-vugs, depending on vug interconnection. Separate vugs are connected only through interparticle pore networks and do not contribute to permeability. Touching vugs are independent of rock fabric and form an interconnected pore system enhancing the permeability. Accurate characterization of pore structure of carbonate reservoirs is essential for design and implementation of enhanced oil recovery processes. However...

The permeability of capillaries among the small granule-containing cells in rat superior cervical ganglia, an ultrastructural lanthanum tracer study

Yat-Pang Chau; Chung-Liang Chien; Kuo-Shyan Lu
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
36.793296%
The permeability of blood capillaries associated with small granule-containing (SGC) cells in rat superior cervical ganglia was investigated at ultrastructural level by employing ionic lanthanum as an electron dense tracer. In rat superior cervical ganglia, the majority of blood capillaries were nonfenestrated. Both fenestrated and nonfenestrated capillaries were observed in the area associated with SGC cells. Lanthanum tracer was observed in the lumina1 surface, the interendothelial cleft and the subendothelial perivascular spaces of both fenestrated and nonfenestrated capillaries associated with SGC cells. The external lamina of the Schwann cell which surrounded the neurons, nerve fibres and SGC cells were clearly delineated by the lanthanum tracer. Furthermore, the perineuronal space, the periaxonal space, and the pericellular space of the SGC cells were readily accessible to the lanthanum ion. The results demonstrated an absence of blood-nerve barrier, bloodganglionic and blood-SGC cell barrier to the lanthanum ion in the parenchyma1 area of the SGC cells in rat superior cervical ganglia. It is proposed that lanthanum may pass through the endothelial cells via 1) the fenestrae of fenestrated capillaries, 2) the intercellular junctions of both fenestrated and nonfenestrated capillaries...

Identifying downhole fracture characteristics using in-situ fluorescence monitoring : the results and interpretation of a large-scale radially divergent tracer experiment conducted in a dolomite aquifer

Melaney, Michael
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 4342056 bytes; application/pdf
EN; EN
Relevância na Pesquisa
36.89827%
In several field studies it was concluded that highly transmissive features transmit the majority of solute mass in horizontally-fractured bedrock aquifers. The purpose of this investigation is to develop a new technique for determining the location and relative role of hydraulically connected fracture features with respect to solute transport. To explore this, a radial-divergent tracer experiment was conducted in a four-borehole array completed through a horizontally-fractured dolomite of Silurian age in Smithville, Ontario, Canada. The injection interval included several hydraulically-identified features located in the Upper Eramosa member of the Lockport formation. 496 L of Lissamine FF (a conservative fluorescent dye tracer at a concentration of 200 mg/L) was injected at a rate of 23.25 L/min +/- 1 %. The arrival of fluorescent tracer was detected in a series of open monitoring wells located in a down gradient direction using a submersible fluorometer equipped with a pressure transducer. Correlating the fluorescence signals at depth with hydraulically-identified features provided an in-situ measure that identified the vertical intersection and relative role of each feature with respect to mass transport. FRAC3DVS a discrete fracture finite element model was used to simulate the tracer experiment. Based on the results of the tracer experiment and numerical simulations...

A comparison of amperometric and spectrophotometric methods for the iodide concentration measurement: a tracer in produced water from offshore oil reservoirs

Souza,Flávia C.; Silva,Davi Augusto I. da; Ribeiro,Márcia S.; Faria,Roberto B.; Melo,Maria A.; Toledo,Roberta M. M.; D'Elia,Eliane
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2013 EN
Relevância na Pesquisa
36.710527%
Amperometric and spectrophotometric methods were developed for measuring iodide tracer concentration in water produced from offshore oil reservoirs. The amperometric method exhibited a linear response from 1 to 10 mg L-1 with limits of detection and of quantification of 0.2 and 0.6 mg L-1, respectively. The spectrophotometric method also exhibited a linear response from 1 to 10 mg L-1 with limits of detection and of quantification of 1 and 3 mg L-1, respectively. Both methods showed to be accurate, linear, homoscedastic and their recoveries were 101 ± 2 and 100 ± 3%, respectively, while the recoveries for produced reservoir water samples (fortified with iodide) were 97 ± 7 and 100 ± 3%, respectively. High amounts of sulfate interfere in the spectrophotometric method. Both methods are promising, simple and inexpensive alternatives to ion chromatography for the detection of iodide tracer in produced water reservoir samples.

Complementary use of tracer and pumping tests to characterize a heterogeneous channelized aquifer system in New Zealand

Dann, Rodney; Close, M; Pang, L; Flintoft, M J; Hector, R P
Fonte: Verlag-Heinz Heise, GmbH & Co KG Publicador: Verlag-Heinz Heise, GmbH & Co KG
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.588347%
The combined use of pumping and tracer test data enabled the derivation of equivalent average hydraulic conductivities (K avg) for each test in a heterogeneous channelized alluvial aquifer, whereas K values of the preferential flow paths were two orders o

On the distribution of silicic acid as a frontal zone tracer in the Indian sector of the Southern Ocean

Prego, R.; Barciela, Mª del Carmen; Park, Y. H.; Morvan, J.; Poncin, J.; Tréguer, P.
Fonte: CSIC - Instituto de Ciencias del Mar (ICM) Publicador: CSIC - Instituto de Ciencias del Mar (ICM)
Tipo: Artículo Formato: 449355 bytes; application/pdf
ENG
Relevância na Pesquisa
36.588347%
Publicación online disponible en: http://www.icm.csic.es/scimar/index.php; The subantarctic frontal zone surveyed during the April-May 1991 SUZIL cruise in the Crozet-Kerguelen-Amsterdam area shows a strong horizontal (north to south) gradient of dissolved silicate, increasing with depth, from 5 to 10 µmolSi kg-1 at 100 m, and 10 to 70 µmolSi kg-1 at 600 m. The northern limit of this frontal zone, which is formed by the confluence of the Subtropical and Subantarctic Fronts, is delimited at the surface by the 2 µmolSi kg-1 silicate isoline. Silicate-salinity diagrams also allow different water regimes to be positioned relative to the frontal zone. This sloping interface is between two water bodies, one to the north with more saline subtropical waters of less concentrated silicate than the southern one, corresponding to subantarctic waters which are less saline and richer in silicate. It is concluded that dissolved silicate can be used as a useful tracer of frontal zone water masses in the Indian sector of the Southern Ocean, providing a sound complement to other hydrographic data.; This paper is supported by the Spanish project, ANT90-123-E, financed by the Comisión Interministerial de Ciencia y Tecnología.; Peer reviewed

A local composition model for the prediction of mutual diffusion coefficients in binary liquid mixtures from tracer diffusion coefficients

Zhu, Qingyu; Moggridge, Geoff D.; D?Agostino, Carmine
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; accepted version
EN
Relevância na Pesquisa
36.793296%
This is the accepted manuscript. The final version is available at http://www.sciencedirect.com/science/article/pii/S0009250915002821.; In a recent publication (Moggride, 2012a), a simple equation was shown to accurately predict the mutual diffusion coefficients for a wide range of non-ideal binary mixtures from the tracer diffusion coefficients and thermodynamic correction factor, on the physical basis that the dynamic concentration fluctuations in the liquid mixture result in a reduction of the mean thermodynamic correction factor relative to the hypothetical case in which such fluctuations do not occur. The analysis was extended to cases where strong molecular association was hypothesised to occur in the form of dimerization of a polar species in mixtures with a non-polar one. This required modification of the average molecular mobility in the form of doubling the tracer diffusivity of the dimerized species (Moggridge, 2012b). Predictions were found to show good accuracy for the mixtures investigated. One of the difficulties with this approach is that it is an a posteriori correction: there is no a priori way of knowing whether strong cluster formation influences the observed molecular mobility, or what the appropriate size of the cluster is. In this work...

Assessment of isotopically exchangeable Al in soil materials using Al-26 tracer

Kleja, D; Standring, W; Oughton, D; Gustafsson, J P; Fifield, L Keith; Fraser, A
Fonte: Pergamon-Elsevier Ltd Publicador: Pergamon-Elsevier Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.588347%
The solubility of aluminium (Al) in many acidic soils is controlled by complexation reactions with soil organic matter. In such soils, Al solubility is theoretically a function of the pool size of "active" Al, i.e., the total amount of Al that equilibrates with the soil solution within a defined period of time. To date, no reliable measurements of "active" Al in soil materials exist. In this study, we determined the isotopically exchangeable pool of Al (EAl) as an operationally defined assessment of "active" Al in acidic mineral soils. The suitability of CuCl2 and pyrophosphate (Na4P2 O7) as extractants for "active" Al was also evaluated. Eleven samples, mostly from spodic B horizons, were spiked with carrier-free 26Al and equilibrated for different time periods (1-756 h). The size of the Al pool with which the 26Al tracer exchanged increased with time during the whole experimental period. Thus, contact time between solid and solution phases needs to be defined when assessing the "active" Al pool. Values of EAl obtained after 1 to 5 d of equilibration were equal to the amount of CuCl2 extractable Al, but considerably smaller than the Na4P2O7-extractable pool. Equilibration times greater than 5 d resulted in CuCl2 extractable Al concentrations that under-estimated the "active" Al pool. Three of the investigated samples were rich in imogolite-type materials (ITM). In these samples...

On the boundary conditions in tracer transport models for fractured porous underground formations

Coronado,M; Ramírez-Sabag,J; Valdiviezo-Mijangos,O
Fonte: Sociedad Mexicana de Física Publicador: Sociedad Mexicana de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2007 EN
Relevância na Pesquisa
36.962075%
A boundary condition traditionally used in analytical models for tracer or contaminant pulse transport in porous underground formations gives the tracer concentration at the injection border as a discontinuous function in time. It has recently been shown that this condition leads to a physically improper pulse behavior. Models using sounder boundary conditions are already available for non-fractured porous media, but not for fractured media, where the traditional condition is commonly employed which can potentially lead to errors. We develop two new formulations to describe tracer tests in fractured media. They set conditions (i) on the total amount of injected tracer and (ii) on the tracer flow. The new formulations are compared against the traditional debatable model by examining tracer breakthrough curve differences. It has been found that they are important at small Peclet numbers. Differences are analyzed in two ways, by (a) employing typical model parameter values, and (b) fitting the three models to the same field tracer data set, and comparing the resulting model parameter values. In the first case the breakthrough curve difference has been quantified at 25%, and in the field tests considered in the second case it was from 1% to 10%. In general these discrepancies are small...

A forced-gradient tracer test on the Hansrivier Dyke: Beaufort West, South Africa

van Wyk,Y; Witthueser,K
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2011 EN
Relevância na Pesquisa
36.853071%
A field-scale pumping test and uranin tracer test was carried out at Hansrivier Farm in Beaufort West to determine the hydraulic properties of the Hansrivier Dyke/Karoo sedimentary rock aquifer. Analysis of borehole images and pumping test results reveal that the fractured-rock aquifer is highly transmissive due to the influence of the Hansrivier Dyke; however its influence is concentrated on extremely limited conductive zones. Results of the tracer test show that chemical transport can take place via multiple flow paths with differing hydraulic properties, such as fracture aperture, connectivity and permeability. Furthermore, diffusion of a tracer into fractures and rock matrix has a universal retardatory travel time due to the various flow paths. In order to interpret the tracer test data, the Single Fissure Dispersion Model (SFDM) was used for inverse modelling of the breakthrough curves. The resulting effective diffusion coefficients are comparable with laboratory-derived values, and are therefore considered to be representative of the investigated part of the aquifer.