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Numerical experiments, presented in a companion paper, have been performed in which the zonal-mean state of the stratosphere in a comprehensive, stratosphere-resolving, general circulation model is strongly relaxed (or ‘‘nudged’...
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Numerical experiments, presented in a companion paper, have been performed in which the zonal-mean state of the stratosphere in a comprehensive, stratosphere-resolving, general circulation model is strongly relaxed (or ‘‘nudged’’) toward the evolution of a reference sudden warming event in order to investigate its influence on the freely evolving troposphere below. Similar approaches have been used in a number of other studies. This raises the question of whether such an artificial relaxation induces the adiabatic and diabatic adjustments expected below the region of nudging, even in the absence of the stratospheric wave driving responsible for the reference event. Motivated by this question, the zonally symmetric quasigeostrophic diabatic response to zonal forces (representing wave driving) in a system nudged to a time-dependent reference state is studied. In the presence of wave driving in the nudging region that differs from the reference state, the meridional mass circulation of the reference state is reproduced only in the region below the nudging up to a correction that is inversely proportional to the strength of the nudging. The anomalous circulation is confined because of an effective boundary condition at the interface of the nudging layer. The nudging also produces an artificial ‘‘spongelayer feedback’’ immediately below the region of the nudging in response to differences in the tropospheric wave driving. The strength of this artificial feedback is closely related to the strength of the effective boundary condition; however, the time scale required for the sponge-layer feedback to be established is typically much longer than that required for the confinement.
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Fields from a pulse source, propagating in a soil with typified inhomogeneities, have been calculated using a previously developed algorithm for solving the direct problem of georadiolocation. The previously designed georadar Grot...
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Fields from a pulse source, propagating in a soil with typified inhomogeneities, have been calculated using a previously developed algorithm for solving the direct problem of georadiolocation. The previously designed georadar Grot has been used in natural measurements of the coordinates of geological exploration wells in a commercial deposit. An analysis of the results of numerical simulation and natural measurements has shown that the georadar Grot (equipped with control and data processing programs) satisfies the requirements to the key georadar characteristics (dynamic range, compactness, and low power consumption) in expedition study of lunar soils.
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Recent satellite observations suggested that medium-depth heavy rain systems (i.e., warm-type heavy rainfall) were predominantly found in the Korean peninsula under moist-adiabatically near neutral conditions in contrast to the tr...
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Recent satellite observations suggested that medium-depth heavy rain systems (i.e., warm-type heavy rainfall) were predominantly found in the Korean peninsula under moist-adiabatically near neutral conditions in contrast to the traditional view that deep convection induced by convective instability produced heavy rainfall (i.e., cold-type heavy rainfall). In order to examine whether a numerical model could explain the microphysical evolution of the warm-type as well as cold-type heavy rainfall, numerical experiments were implemented with idealized thermodynamic conditions. Under the prescribed humid and weakly unstable conditions, the warm-type experiments resulted in a lower storm height, earlier onset of precipitation, and heavier precipitation than was found for the cold-type experiments. The growth of ice particles and their melting process were important for developing cold-type heavy rainfall. In contrast, the collision and coalescence processes between liquid particles were shown to be the mechanism for increasing the radar reflectivity toward the surface in the storm core region for the warm-type heavy rainfall.
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Theshort-termforecasting ofwave energy is important to provide guidance for the electric power operation and power transmission system and to enhance the efficiency of energy capture and conversion. This study produced a numerical...
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Theshort-termforecasting ofwave energy is important to provide guidance for the electric power operation and power transmission system and to enhance the efficiency of energy capture and conversion. This study produced a numerical forecasting experiment of the China Sea wave energy using WAVEWATCH-III (WW3, the latest version 4.18) wave model driven by T213 (WW3-T213) and T639 (WW3-T639) wind data separately.Then the WW3-T213 and WW3-T639 were verified and compared to build a shorttermwave energy forecasting structure suited for the China Sea. Considering the value of wave power density (WPD), "wave energy rose," daily and weekly total storage and effective storage of wave energy, this study also designed a series of short-termwave energy forecasting productions. Results show that both the WW3-T213 and WW3-T639 exhibit a good skill on the numerical forecasting of the China Sea WPD, while the result of WW3-T639 is much better. Judging from WPD and daily and weekly total storage and effective storage of wave energy, great wave energy caused by cold airs was found. As there are relatively frequent cold airs in winter, early spring, and later autumn in the China Sea and the surrounding waters, abundant wave energy ensues.
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Using the contact dymanics method together with the finite element method, we simulate the uniaxial compression of assemblies of elastic cylinders. The numerical model accounts for finite deformations of the particles through the ...
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Using the contact dymanics method together with the finite element method, we simulate the uniaxial compression of assemblies of elastic cylinders. The numerical model accounts for finite deformations of the particles through the neo-Hookean constitutive equation and solid friction between the particles. A quantitative comparison with experiments carried out with centimetric rubberlike cylinders, with local deformations of the particles determined by image correlation, is proposed. We show that the simulations accurately capture the details of both the microstructure and the macroscopic behavior of the real granular system, demonstrating the relevancy of the numerical approach.
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The maximal Lyapunov characteristic exponent of chaotic motion was calculated as a function of the system energy by numerical integration of the Henon-Heiles problem. Contrary to the conclusions of Benettin et al. [4], this depend...
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The maximal Lyapunov characteristic exponent of chaotic motion was calculated as a function of the system energy by numerical integration of the Henon-Heiles problem. Contrary to the conclusions of Benettin et al. [4], this dependence is not exponential but is close to a power law. As to the energy dependence of dynamic entropy, it is close to an exponential law, in agreement with [4]. (C) 2003 MAIK "Nauka / Interperiodica". [References: 12]
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The layered model in Part I was used to simulate the internal tide in a stratified, two layer, and rectangular sea area with step-like topography. The internal tide current velocities of the upper and lower layers and the interfac...
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The layered model in Part I was used to simulate the internal tide in a stratified, two layer, and rectangular sea area with step-like topography. The internal tide current velocities of the upper and lower layers and the interfacial elevations were computed and the effect of the upper layer water depth and den- sity difference were studied. Numerical experiments verified that the model can correctly simulate internal tides. The model was also applied to the northwestern part of the South China Sea to simulate the internal tides where with real topography. The distributions of internal tide amplitude in interfaces were delineated.
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A novel dispersion formulation of the 2D alternating-direction implicit (ADI) finite-difference time-domain (FDTD) method is presented. The formulation is based on an increasing process analysis of the monochromatic wave in free s...
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A novel dispersion formulation of the 2D alternating-direction implicit (ADI) finite-difference time-domain (FDTD) method is presented. The formulation is based on an increasing process analysis of the monochromatic wave in free space. A numerical experiment scheme is designed to verify the accuracy of the proposed formulation. The results obtained from the proposed formulation are in a good agreement with those from the numerical experiments, and the proposed formulation is more accurate than those reported in the literature. (c) 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE 16: 584-587, 2006.
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The value of the cosmological constant is one of the major puzzles of modern cosmology: it is tiny but nonzero. Sorkin predicted, from the Causet approach to quantum gravity, that the cosmological constant has quantum fluctuations...
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The value of the cosmological constant is one of the major puzzles of modern cosmology: it is tiny but nonzero. Sorkin predicted, from the Causet approach to quantum gravity, that the cosmological constant has quantum fluctuations. The predicted order of magnitude of the fluctuations agrees with the subsequently observed value of the cosmological constant. We had earlier developed an analogy between the cosmological constant of the universe and the surface tension of fluid membranes. Here we demonstrate by computer simulations that the surface tension of a fluid membrane has statistical fluctuations stemming from its discrete molecular structure. Our analogy enables us to view these numerical experiments as probing a small and fluctuating cosmological constant. Deriving insights from our analogy, we show that a fluctuating cosmological constant is a generic feature of quantum gravity models and is far more general than the specific context in which it was originally proposed. We pursue and refine the idea of a fluctuating cosmological constant and work towards making further testable predictions.
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The phenomenon of filling flow, which may take place inside the fissures or cavities of maritime structures, due to the action of waves, has been studied mostly from an analytical point of view. The aim of this paper was to invest...
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The phenomenon of filling flow, which may take place inside the fissures or cavities of maritime structures, due to the action of waves, has been studied mostly from an analytical point of view. The aim of this paper was to investigate such a process through an experimental approach, using both physical and numerical models. The most important filling flow properties were evaluated under different wave conditions (expressed in terms of acceleration and angular frequency). Numerical and physical results were compared with each other and with the analytical formulations proposed in literature. Good agreement was found between the experimental and the analytical results, especially for the velocity of the backflow jet and for the pressure inside the cavity. Finally, an empirical formula for the prediction of the pressures induced by the filling flow, related to the wave and the cavity geometry features, was proposed.
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