Comparison of three models of dispersion in dual porosity media     

E. Carlier 《Environmental Geology》2008,55(2):433-440

The work presented in this paper shows that the probabilistic approach as well as the fractional Brownian motion model are reliable to simulate the dispersion of contaminant in the dual porosity media. Three models were tested on experimental data obtained by tracer tests in chalk characterized by a primary and a secondary porosity: a numerical model (MT3DMS), a probabilistic model based on the Bayesian approach and a fractional Brownian model. By using Einstein’s rule, it is demonstrated that the dispersion coefficient is time dependent and that the dispersion is ballistic which is a particular case of superdiffusion. A test of sensitivity was carried out and shows that the numerical model is slightly suitable to simulate the concentration in time and space for a given discharge starting from the physical parameters obtained by calibration for an other discharge because of the great sensitivity of its parameters according to the hydrodynamic conditions. On the other hand, the variability of the parameters of the two other models does not generate important errors on the values of simulated concentrations when other hydrodynamic conditions are considered.  相似文献   

Electromagnetic measurements of tidal transports in estuaries     

Erick M. Swenson 《Estuaries and Coasts》1981,4(3):161-166

Measurement of the electric potential produced across a tidal stream is an inexpensive and relatively maintenance free means of monitoring volume flow. Comparison of the electric signal to transports determined from current meter records is used to calibrate the system. A volume flow of 100 m³ per sec will induce a potential near 1 mV. Salinity and temperature changes at the electrodes will induce potentials of 500 μV per ‰ and 350 μV per °C. Transport estimates may need to be corrected for such effects. Examples of measurements made at two locations, Great Bay, New Hampshire, and Lake Pontchartrain, Louisiana, illustrate that the method is capable of yielding volume flow measurements with an uncertainty of about 15%.  相似文献   

Radiogenic lead mobility in the Shea Creek unconformity-related uranium deposit (Saskatchewan,Canada): migration pathways and Pb loss quantification     

Philippe Kister  Michel Cuney  Viacheslav N. Golubev  Jean-Jacques Royer  Christian Le Carlier De Veslud  Jean-Claude Rippert 《Comptes Rendus Geoscience》2004,336(3):205-215

The average Pb/U ratio of the Shea Creek unconformity-type uranium deposit has been estimated at 0.071±0.015. The calculation was performed on a volume enclosing the orebody to take into account the possible radiogenic lead migration within the ore zone. Despite this precaution, this ratio is significantly lower than the expected ratio (0.211) assuming a main U deposition around 1315 Ma, as suggested by previous UPb isotopic dating. Although part of the radiogenic lead can be trapped as galena within the orebody, about 60% of Pb have migrated more than 700 m away from the orebody, preferentially along the unconformity. To cite this article: P. Kister et al., C. R. Geoscience 336 (2004).  相似文献   

Combination of FEM and CMA‐ES algorithm for transmissivity identification in aquifer systems          下载免费PDF全文

Hassan Smaoui  Lahcen Zouhri  Sami Kaidi  Erick Carlier 《水文研究》2018,32(2):264-277

In this paper, we propose a coupling of a finite element model with a metaheuristic optimization algorithm for solving the inverse problem in groundwater flow (Darcy's equations). This coupling performed in 2 phases is based on the combination of 2 codes: This is the HySubF‐FEM code (hydrodynamic of subsurface flow by finite element method) used for the first phase allowing the calculation of the flow and the CMA‐ES code (covariance matrix adaptation evolution strategy) adopted in the second phase for the optimization process. The combination of these 2 codes was implemented to identify the transmissivity field of groundwater by knowing the hydraulic head in some point of the studied domain. The integrated optimization algorithm HySubF‐FEM/CMA‐ES has been validated successfully on a schematic case offering an analytical solution. As realistic application, the integrated optimization algorithm HySubF‐FEM/CMA‐ES was applied to a complex groundwater in the north of France to identify the transmissivity field. This application does not use zonation techniques but solves an optimization problem at each internal node of the mesh. The obtained results are considered excellent with high accuracy and fully consistent with the hydrogeological characteristics of the studied aquifer.However, the various numerical simulations performed in this paper have shown that the CMA‐ES algorithm is time‐consuming. Finally, the paper concludes that the proposed algorithm can be considered as an efficient tool for solving inverse problems in groundwater flow.  相似文献   

Water Defluoridation Using Sequentially Coupled Moringa oleifera Seed Extract and Electrocoagulation     

Brent Laney  Oscar M. Rodriguez-Narvaez  Braimah Apambire  Erick R. Bandala 《Ground Water Monitoring & Remediation》2020,40(3):67-74

Moringa oleifera (MO) seed extract coupled with electrocoagulation (EC) was used to remove fluoride from water. Different MO extract volumes (5.0, 12.5, and 25.0 mL of MO extract per water liter) were coupled with EC, using aluminum electrodes at different current density values (J = 0.7, 2.0, and 3.3 mA/cm²) and different electrode separations (1.0, 2.0, and 4.0 cm), tested in batch and recirculation experiments. Control experiments using MO extract and EC alone achieved 5% and 54% water defluoridation, respectively. Best experimental batch conditions were achieved using 12.5 mL of MO extract followed by EC (3.3 mA/cm²) with a 1.0 cm electrode separation, producing >90% fluoride removal. Recirculation experiments with the EC reactor were performed with DI water and tap water using 1.0 cm electrode separation, 12.5 mL of MO extract and different current densities. More than 90% fluoride removal was achieved with the EC/MO process, using 3.3 mA/cm², in both DI and tap water after 30 and 60 min, respectively. An energy consumption index (ECI) was developed, which showed that 1.51 and 0.67 W/h/mg were achieved for batch experiments of EC alone and EC/MO extract, respectively. For EC/MO extract, recirculation experiments with tap and DI water resulted in 0.35 and 0.22 W/h/mg, respectively. A cost analysis showed that $0.18 will be needed to treat one cubic meter of water.  相似文献   

International Pellet Watch: Global monitoring of persistent organic pollutants (POPs) in coastal waters. 1. Initial phase data on PCBs, DDTs, and HCHs   总被引：1，自引：0，他引：1  

Yuko Ogata  Kaoruko Mizukawa  Satoru Iwasa  Yukie Mato  Keiji Okuda  Michio Murakami  Ruchaya Booyatumanondo  Le Quang Dung  Carlos Miguez  Charles Moore  Steven Weerts  Erick Burres  Michael Van Velkenburg  Richard C. Lang  Brenda Danner  Richard C. Thompson 《Marine pollution bulletin》2009,58(10):1437-1446

Samples of polyethylene pellets were collected at 30 beaches from 17 countries and analyzed for organochlorine compounds. PCB concentrations in the pellets were highest on US coasts, followed by western Europe and Japan, and were lower in tropical Asia, southern Africa and Australia. This spatial pattern reflected regional differences in the usage of PCBs and was positively correlated with data from Mussel Watch, another monitoring approach. DDTs showed high concentrations on the US west coast and in Vietnam. In Vietnam, DDT was predominant over its metabolites (DDE and DDD), suggesting the principal source may be current usage of the pesticide for malaria control. High concentrations of pesticide HCHs were detected in the pellets from southern Africa, suggesting current usage of the pesticides in southern Africa. This study demonstrates the utility and feasibility of the International Pellet Watch approach to monitor POPs at a global scale.  相似文献   

A study of dissipation of wind-waves by mud at Cassino Beach,Brazil: Prediction and inversion     

W. Erick Rogers  K. Todd Holland 《Continental Shelf Research》2009

The impact of a non-rigid seafloor on the wave climate at Cassino Beach, Brazil, May–June 2005 is studied using field measurements and a numerical wave model. The measurements consist of wave data at four locations; rheology and mud thickness from grab samples; and an estimate of the horizontal distribution of mud based on echo-soundings. The dissipation of waves by a non-rigid bottom is represented in the wave model by treating the mud layer as a viscous fluid. Applied for 431 time periods, the model without this type of dissipation has a strong tendency to overpredict nearshore wave energy, except during a period of large storm waves. Two model variations which include this dissipation have a modest tendency to underpredict the nearshore wave energy. An inversion methodology is developed and applied to infer an alternate mud distribution which, when used with the wave model, yields the observed waveheights.  相似文献   

Forecasting marine debris spill accumulation patterns in the south-eastern Australia water: an intercomparison between global ocean forecast models     

Liao  Fanglou  Wang  Xiao Hua  Fredj  Erick 《Ocean Dynamics》2023,73(2):91-106

Ocean Dynamics - Forecasting transport and fates of marine debris spilled from lost ship containers is increasingly important. This paper builds a forecast framework by forcing a state-of-the-art...  相似文献   

Passive (Micro-) Seismic Event Detection by Identifying Embedded “Event” Anomalies Within Statistically Describable Background Noise     

Erick Baziw  Gerald Verbeek 《Pure and Applied Geophysics》2012,169(12):2107-2126

Among engineers there is considerable interest in the real-time identification of “events” within time series data with a low signal to noise ratio. This is especially true for acoustic emission analysis, which is utilized to assess the integrity and safety of many structures and is also applied in the field of passive seismic monitoring (PSM). Here an array of seismic receivers are used to acquire acoustic signals to monitor locations where seismic activity is expected: underground excavations, deep open pits and quarries, reservoirs into which fluids are injected or from which fluids are produced, permeable subsurface formations, or sites of large underground explosions. The most important element of PSM is event detection: the monitoring of seismic acoustic emissions is a continuous, real-time process which typically runs 24?h a day, 7?days a week, and therefore a PSM system with poor event detection can easily acquire terabytes of useless data as it does not identify crucial acoustic events. This paper outlines a new algorithm developed for this application, the so-called SEED? (Signal Enhancement and Event Detection) algorithm. The SEED? algorithm uses real-time Bayesian recursive estimation digital filtering techniques for PSM signal enhancement and event detection.  相似文献   

Supernova remnants, planetary nebulae and the distance to NGC 4214     

Michael A. Dopita  Daniela Calzetti  Jesús Maíz Apellániz  William P. Blair  Knox S. Long  Max Mutchler  Bradley C. Whitmore  Howard E. Bond  John MacKenty  Bruce Balick  Marcella Carollo  Michael Disney  Jay A. Frogel  Robert O’Connell  Donald Hall  Jon A. Holtzman  Randy A. Kimble  Patrick McCarthy  Francesco Paresce  Abhijit Saha  Alistair R. Walker  Joe Silk  Marco Sirianni  John Trauger  Rogier Windhorst  Erick Young 《Astrophysics and Space Science》2010,330(1):123-131

We present narrow band, continuum subtracted Hα, [S ii], Hβ, [O iii] and [O ii] data taken with the Wide Field Camera 3 on the Hubble Space Telescope in the nearby dwarf starburst galaxy NGC 4214. From these images, we identify seventeen new planetary nebula candidates, and seven supernova remnant candidates. We use the observed emission line luminosity function of the planetary nebulae to establish a new velocity-independent distance to NGC 4214. We conclude that the PNLF technique gives a reddening independent distance to NGC 4214 of 3.19±0.36 Mpc, and that our current best-estimate of the distance to this galaxy ids 2.98±0.13 Mpc.  相似文献