3,054 research outputs found
Development of new flux splitting schemes
Maximizing both accuracy and efficiency has been the primary objective in designing a numerical algorithm for CFD. This is especially important for solution of complex three-dimensional systems of Navier-Stokes equations which often include turbulence modeling and chemistry effects. Recently, upwind schemes have been well received for both their capability of resolving discontinuities and their sound theoretical basis in characteristic theory for hyperbolic systems. With this in mind, two new flux splitting techniques are presented for upwind differencing
Development of a new flux splitting scheme
The use of a new splitting scheme, the advection upstream splitting method, for model aerodynamic problems where Van Leer and Roe schemes had failed previously is discussed. The present scheme is based on splitting in which the convective and pressure terms are separated and treated differently depending on the underlying physical conditions. The present method is found to be both simple and accurate
Evolutionary strategy search algorithm for fast block motion estimation
The evolutionary strategy search (ESS) algorithm is a novel method for implementing fast block motion estimation (ME) using evolutionary
strategy (ES). ESS uses a combination of ideas based on existing search strategies and employs a novel (1Ć¾sl) ES implementation. It is essentially a succession of random searches, but by controlling the placement and distribution of these searches in a simple way, it proves
possible to achieve comparable motion vector accuracy to the more established ME strategies, but with enhanced convergence speed
Effects of Atmospheric Absorption of Incoming Radiation on the Radiation Limit of the Troposphere: Reply
In response to a comment on their previous note about the Voigt line profile, here the authors clarify relevant statements and numeric algorithms in the original note
Oxygen defect in YBa\u3csub\u3e2\u3c/sub\u3eCu\u3csub\u3e3\u3c/sub\u3eO\u3csub\u3ex\u3c/sub\u3e: An x-ray photoemission approach
A combined x-ray photoemission and diamagnetic-susceptibility study of YBa2Cu3Ox with xā6 and 7 has been performed, with emphasis on the oxygen defect and the effect of heating in vacuum. By comparing spectra taken at these two oxygen contents, the core levels observed in the O 1s and Ba 4d spectral range are identified. Peak-intensity analysis indicates (1) that the oxygen released during the in situ heating is derived from or near the Cu-O-Cu-O chains of YBa2Cu3O7 and (2) that there is a random distribution of oxygen defects in or near these chains leading to two chemically dissimilar barium atoms even in single-orthorhombic-phase samples
Break-junction tunneling measurements of the high-\u3ci\u3eT\u3c/i\u3e\u3csub\u3e\u3ci\u3ec\u3c/i\u3e\u3c/sub\u3e superconductor Y\u3csub\u3e1\u3c/sub\u3eBa\u3csub\u3e2\u3c/sub\u3eCu\u3csub\u3e3\u3c/sub\u3eO\u3csub\u3e9- Ī“ \u3c/sub\u3e
Current-voltage tunneling characteristics in a high-critical-temperature superconducting material containing predominately Y1Ba2Cu3O9- Ī“ have been measured using the break-junction technique. Sharp gap structure was observed, with the largest superconductive energy gap measured to be Ī=19.5Ā±1 meV, assuming a superconductor-insulator-superconductor junction. This energy gap corresponds to 2Ī/kBTc=4.8 at T=4 K, for a critical temperature of 93 K (midpoint of the resistive transition)
On the Basic Equations for the Second-order Modeling of Compressible Turbulence
Equations for the mean and the turbulence quantities of compressible turbulent flows are derived in this report. Both the conventional Reynolds average and the mass-weighted Favre average were employed to decompose the flow variable into mean and turbulent quantities. These equations are to be used later in developing second-order Reynolds stress models for high-speed compressible flows. A few recent advances in modeling some of the terms in the equation due to compressibility effects are also summarized
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