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Natural Hazards - To reduce and prevent significant economic flood losses, reliable tools are required to estimate potential river inundation effects. This paper focuses on the estimation of direct... 相似文献
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Jorge Ramón Alicia Correa Edison Timbe Giovanny M. Mosquera Enma Mora Patricio Crespo 《水文研究》2021,35(6):e14209
Hydrogeochemical based mixing models have been successfully used to investigate the composition and source identification of streamflow. The applicability of these models is limited due to the high costs associated with data collection and the hydrogeochemical analysis of water samples. Fortunately, a variety of mixing models exist, requiting different amount of data as input, and in data scarce regions it is likely that preference will be given to models with the lowest requirement of input data. An unanswered question is if models with high or low input requirement are equally accurate. To this end, the performance of two mixing models with different input requirement, the mixing model analysis (MMA) and the end-member mixing analysis (EMMA), were verified on a tropical montane headwater catchment (21.7 km2) in the Ecuadorian Andes. Nineteen hydrogeochemical tracers were measured on water samples collected weekly during 3 years in streamflow and eight potential water sources or end-members (precipitation, lake water, soil water from different horizons and springs). Results based on 6 conservative tracers, revealed that EMMA (using all tracers) and MMA (using pair-combinations out of the 6 conservative ones), identified the same end-members: rainfall, soil water and spring water., as well as, similar contribution fractions to streamflow from rainfall 21.9% and 21.4%, soil water 52.7% and 52.3%, and spring water 26.1% and 28.7%, respectively. Our findings show that a hydrogeochemical mixing model requiring a few tracers can provide similar outcomes than models demanding more tracers as input data. This underlines the value of a preliminary detailed hydrogeochemical characterization as basis to derive the most cost-efficient monitoring strategy. 相似文献
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Edison Liang 《Astrophysics and Space Science》2007,307(1-3):309-313
We review recent PIC simulation results which show that double-sided irradiation of a thin over-dense plasma slab with ultra-intense
laser pulses from both sides can lead to sustained comoving Poynting flux acceleration of electrons to energies much higher
than the conventional ponderomotive limit. The result is a robust power-law electron momentum spectrum similar to astrophysical
sources. We discuss future ultra-intense laser experiments that may be used to simulate astrophysical particle acceleration. 相似文献
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Field survey of the 1994 Mindoro Island,Philippines tsunami 总被引：2，自引：0，他引：2
Fumihiko Imamura Costas E. Synolakis Edison Gica Vasily Titov Eddie Listanco Ho Jun Lee 《Pure and Applied Geophysics》1995,144(3-4):875-890
This is a report of the field survey of the November 15, 1994 Mindoro Island, Philippines, tsunami generated by an earthquake (M=7.0) with a strike-slip motion. We will report runup heights from 54 locations on Luzon, Mindoro and other smaller islands in the Cape Verde passage between Mindoro and Luzon. Most of the damage was concentrated along the northern coast of Mindoro. Runup height distribution ranged 3–4 m at the most severely damaged areas and 2–4 in neighboring areas. The tsunami-affected area was limited to within 10 km of the epicenter. The largest recorded runup value of 7.3 m was measured on the southwestern coast of Baco Island while a runup of 6.1 m was detected on its northern coastline. The earthquake and tsunami killed 62 people, injured 248 and destroyed 800 houses. As observed in other recent tsunami disasters, most of the casualties were children. Nearly all eyewitnesses interviewed described the first wave as a leading-depression wave. Eyewitnesses reported that the main direction of tsunami propagation was SW in Subaang Bay, SE in Wawa and Calapan, NE on Baco Island and N on Verde Island, suggesting that the tsunami source area was in the southern Pass of Verde Island and that the wave propagated rapidly in all directions. The fault plane extended offshore to the N of Mindoro Island, with its rupture originating S of Verde Island and propagating almost directly south to the inland of Mindoro, thereby accounting for the relatively limited damage area observed on the N of Mindoro. 相似文献
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Using average nutritive values of food actually consumed by individuals, this paper identifies regional concentration of hunger (food poverty) and its changes over time in rural India. There is clearly a heavy concentration of hunger in the coastal states of India, with few exceptions, which has persisted over time. Hunger has declined in about half the states of India but has increased in the remaining half. Unfortunately, it seems to have increased in the states that are relatively prosperous and are surplus producers of food. Hence, increased production of food, though important, does not necessarily reduce hunger. A redeeming conclusion of the study is that there has been a general improvement in the quality of food intake, particularly in the states where food poverty has declined. 相似文献
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Edison Caballero Fernando A. Rochinha Marcio Borges Marcio A. Murad 《国际地质力学数值与分析法杂志》2019,43(2):482-500
In this work, we construct a new methodology for enhancing the predictive accuracy of sequential methods for coupling flow and geomechanics while preserving low computational cost. The new computational approach is developed within the framework of the fixed-stress split algorithm procedure in conjunction with data assimilation based on the ensemble Kalman filter (EnKF). In this context, we identify the high-fidelity model with the two-way formulation where additional source term appears in the flow equation containing the time derivative of total mean stress. The iterative scheme is then interlaced with data assimilation steps, which also incorporate the modeling error inherent to the EnKF framework. Such a procedure gives rise to an “enhanced one-way formulation,” exhibiting substantial improvement in accuracy compared with the classical one-way method. The governing equations are discretized by mixed finite elements, and numerical simulation of a 2D slab problem between injection and production wells illustrate the tremendous achievement of the method proposed herein. 相似文献
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Particle acceleration via Poynting vector with toroidal magnetic field is studied in 3D PIC simulation of electron-positron
plasma. We choose two different initial magnetic field configurations to compare how the particle acceleration is affected
by the expansion of electromagnetic wave. In the cylindrical case, the electromagnetic field strength decays as (ct)−2, and particles are accelerated in the radial direction as well as the axial direction. Rayleigh-Taylor instability is also
observed at the center of the cylinder. In the torus case, the field strength decays as (ct)−3, making the acceleration less efficient. Particles accelerated in the axial direction by E × B force creates strong charge separation. 相似文献
10.
Alexander Henderson Edison Liang Pablo Yepes Hui Chen Scott Wilks 《Astrophysics and Space Science》2011,336(1):273-277
Irradiating high-Z targets such as gold with ultra-intense lasers creates electron-positron pairs. In particular, the positron
density in the plasma created by this procedure is higher than that obtained via other laboratory-based methods, with theoretical
maximum densities exceeding 1018 cm−3. All of the significantly contributing processes are well-known and hence we can study this phenomenon using Monte Carlo
simulation. We focus on the latter part of this procedure, the passage of high-energy electrons through the target creating
pairs. In particular, we discuss the usefulness of CERN’s GEANT4 Monte Carlo code in simulating this process. Once this code
is successfully calibrated, we will use it to perform parameter studies, and design future targets to optimize the positron
yield. 相似文献