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381.
At various stages of petroleum reservoir development, we encounter a large degree of geological uncertainty under which a rational decision has to be made. In order to identify which parameter or group of parameters significantly affects the output of a decision model, we investigate decision-theoretic sensitivity analysis and its computational issues in this paper. In particular, we employ the so-called expected value of partial perfect information (EVPPI) as a sensitivity index and apply multilevel Monte Carlo (MLMC) methods to efficient estimation of EVPPI. In a recent paper by Giles and Goda, an antithetic MLMC estimator for EVPPI is proposed and its variance analysis is conducted under some assumptions on a decision model. In this paper, for an improvement on the performance of the MLMC estimator, we incorporate randomized quasi-Monte Carlo methods within the inner sampling, which results in an multilevel quasi-Monte Carlo (MLQMC) estimator. We apply both the antithetic MLMC and MLQMC estimators to a simple waterflooding decision problem under uncertainty on absolute permeability and relative permeability curves. Through numerical experiments, we compare the performances of the MLMC and MLQMC estimators and confirm a significant advantage of the MLQMC estimator. 相似文献
382.
Kenshi Kuma Ryohei Sasayama Nanako Hioki Yuichiroh Morita Yutaka Isoda Tohru Hirawake Keiri Imai Takafumi Aramaki Tomohiro Nakamura Jun Nishioka Naoto Ebuchi 《Journal of Oceanography》2014,70(4):377-387
In the southwestern Okhotsk Sea, the cold water belt (CWB) is frequently observed on satellite images offshore of the Soya Warm Current flowing along the northeastern coast of Hokkaido, Japan, during summertime. It has been speculated that the CWB is upwelling cold water that originates from either subsurface water of the Japan Sea off Sakhalin or bottom water of the Okhotsk Sea. Hydrographic and chemical observations (nutrients, humic-type fluorescence intensity, and iron) were conducted in the northern Japan Sea and southwestern Okhotsk Sea in early summer 2011 to clarify the origin of the CWB. Temperature–salinity relationships, vertical distributions of chemical components, profiles of chemical components against density, and the (NO3 + NO2)/PO4 relationship confirm that water in the CWB predominantly originates from Japan Sea subsurface water. 相似文献
383.
384.
Yutaka Abe 《Earth, Moon, and Planets》2011,108(1):9-14
Protoatmospheres and surface environment of terrestrial protoplanets during the oligarchic accretion phase and the giant impacts
phase are discussed from theoretical points of view. Mars-sized protoplanets form during the stage of the oligarchic growth.
Since protoplanets are formed from more or less ‘local’ planetesimals, the surface environment of the accreting protoplanets
depends on availability of volatile material in planetesimals. Even if no volatile-bearing planetesimals are available, a
gravitationary captured solar composition atmosphere is formed during accretion. In such cases the surface temperature is
always kept under the melting temperature of mantle silicate and only a subsurface magma ocean is formed. Core formation proceeds
under dry conditions, and volatile elements are not partitioned into metallic iron. Accretion of water-bearing planetesimals
results in impact degassing. A surface hydrous magma ocean forms in response to the thermal blanketing effect of the proto-atmosphere.
Then, some volatile materials dissolve into the magma ocean. If we consider reaction with metallic iron, the proto-atmosphere
is likely to be rich in hydrogen. In addition, a large amount of hydrogen may be partitioned into metallic iron under high
pressure, and delivered to the core. In the stage of giant impacts, both dry and water-bearing protoplanets collide on the
proto-Earth. Substantial amount of proto-atmosphere (including water vapor) survives giant impacts. Moreover, giant impacts
on protoplanets with oceans result in relative concentration of water against other gases. 相似文献