2,233 research outputs found
A STOCHASTIC SIMULATION-BASED HYBRID INTERVAL FUZZY PROGRAMMING APPROACH FOR OPTIMIZING THE TREATMENT OF RECOVERED OILY WATER
In this paper, a stochastic simulation-based hybrid interval fuzzy programming (SHIFP) approach
is developed to aid the decision-making process by solving fuzzy linear optimization problems.
Fuzzy set theory, probability theory, and interval analysis are integrated to take into account the
effect of imprecise information, subjective judgment, and variable environmental conditions. A
case study related to oily water treatment during offshore oil spill clean-up operations is conducted
to demonstrate the applicability of the proposed approach. The results suggest that producing a
random sequence of triangular fuzzy numbers in a given interval is equivalent to a normal
distribution when using the centroid defuzzification method. It also shows that the defuzzified
optimal solutions follow the normal distribution and range from 3,000-3,700 tons, given the
budget constraint (CAD 110,000-150,000). The normality seems to be able to propagate
throughout the optimization process, yet this interesting finding deserves more in-depth study
and needs more rigorous mathematical proof to validate its applicability and feasibility. In
addition, the optimal decision variables can be categorized into several groups with different
probability such that decision makers can wisely allocate limited resources with higher
confidence in a short period of time. This study is expected to advise the industries and
authorities on how to distribute resources and maximize the treatment efficiency of oily
water in a short period of time, particularly in the context of harsh environments
Post-glacial sedimentation in a river -dominated epicontinental shelf: The Yellow Sea example
The North Yellow Sea (NYS) and South Yellow Sea (SYS), stretching from the Bohai Sea in the north to the East China Sea (ECS) in the south, represents an end member of modern epicontinental seas. Because of its shallow depths, the Yellow Sea was entirely exposed subaerially during the last glacial maximum. The new post-glacial sea-level curve derived from an extensive local dataset shows a series of rapid flooding events (12--45 mm/y), separated by a series of slow rises (2--6 mm/y). By about 15 ka, sea level had reached -100 m, and seawater entered the SYS. A rapid rise during MWP-1A occurred between 14.7--14.1 ka, sea level jumped from -98 m to -74 m (40 mm/yr). at the end, the sea water had reached the southern edge of the NYS, after which sea level rose again slowly (6 mm/yr) from -72 m to -60 m. Beginning about 11.7 ka, it again jumped, from -60 m to -42 m (MWP-1B), resulting in a rapid westward flooding of the NYS. Sea level then again stagnated (between -42m to -36 m) for about 1.8 ky. Starting about 9.8 ka, the sea-level advanced again from -36m to -16 m at 9.0 ka (MWP-1C), after which most of BS, YS, and ECS had been submerged. Then another slowdown occurred between 9.0--8.0 ka when sea-level rose from -16m to -10m. The last major transgression happened between 8.1 and 7.0 ka (MWP-D), and resulted in Holocene highstand of at least +2 to 4 m along most of Chinese and Korean coastlines. Sequence structures on this epicontinental shelf show strong landward horizontal changes, instead of the vertical changes. The first major deltaic system was developed in the NYS together with the decreased sea-level rise after MWP-1B event, and the intensified summer monsoon and subsequent increased river discharge at about 11 ka. The second subaqueous delta was built in the SYS between 9--7 ka which during another slackened sea-level after MWP-C. The modern subaqueous and subaerial deltas in the west Bahai Gulf have been formed during the sea-level highstand after the last jump of MWP-1D
Anomalous thermoelectric transport of Dirac particles in graphene
We report a thermoelectric study of graphene in both zero and applied
magnetic fields. As a direct consequence of the linear dispersion of massless
particles, we find that the Seebeck coefficient Sxx diverges with 1 /, where
n2D is the carrier density. We observe a very large Nernst signal Sxy (~ 50
uV/K at 8 T) at the Dirac point, and an oscillatory dependence of both Sxx and
Sxy on n2D at low temperatures. Our results underscore the anomalous
thermoelectric transport in graphene, which may be used as a highly sensitive
probe for impurity bands near the Dirac point
Radio-frequency spectroscopy of weakly bound molecules in spin-orbit coupled atomic Fermi gases
We investigate theoretically radio-frequency spectroscopy of weakly bound
molecules in an ultracold spin-orbit-coupled atomic Fermi gas. We consider two
cases with either equal Rashba and Dresselhaus coupling or pure Rashba
coupling. The former system has been realized very recently at Shanxi
University [Wang et al., arXiv:1204.1887] and MIT [Cheuk et al.,
arXiv:1205.3483]. We predict realistic radio-frequency signals for revealing
the unique properties of anisotropic molecules formed by spin-orbit coupling.Comment: 11 pages, 7 figure
Mott Relation for Anomalous Hall and Nernst effects in Ga1-xMnxAs Ferromagnetic Semiconductors
The Mott relation between the electrical and thermoelectric transport
coefficients normally holds for phenomena involving scattering. However, the
anomalous Hall effect (AHE) in ferromagnets may arise from intrinsic spin-orbit
interaction. In this work, we have simultaneously measured AHE and the
anomalous Nernst effect (ANE) in Ga1-xMnxAs ferromagnetic semiconductor films,
and observed an exceptionally large ANE at zero magnetic field. We further show
that AHE and ANE share a common origin and demonstrate the validity of the Mott
relation for the anomalous transport phenomena
A Method of Quantitative Evaluation of Diagenetic Reservoir Facies of Tight Gas Reservoirs With Logging Multi-Parameters: A Case Study in Sulige Area, Northern Ordos Basin, China
Reservoir and flow characteristics of low, ultra-low permeability tight sandstone reservoir were largely controlled by diagenesis in reservoir assessment. In previous studies, diagenesis were researched only by using core analysis data, and it was difficult that diagenetic reservoir facies of the interval and the well without core analysis data were evaluated. Therefore, it was easy and quick that diagenetic reservoir facies were characterized with logging response characteristics which were extracted effectively. Taking tight gas reservoirs for example in Sulige area, northern Ordos Basin, China, logging response characteristics of different classification were analyzed by multiple samples with core analysis data, and the quantitative evaluation index of diagenetic reservoir facies based on logging multi-parameter was set up. A method of quantitative evaluation of diagenetic reservoir facies of tight gas reservoirs with logging multi-parameters was formed in the method of integration of analysis technology of Grey theory, and the accuracy and availability of the method were evaluated. The results shown that non-digitalized problems of diagenetic reservoir facies evaluation was solved by the digitalization method of logging multi-parameters, and the rate of accuracy, of returned classification using methods of mutual test, reached to 91.2%. The results provided a new and effective evaluation approach of low, ultra-low permeability tight sandstone reservoir
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