10,853 research outputs found
Disposition of information entities and adequate level of information presentation in an in-car augmented reality navigation system
No full textRecent Trends in Hearing Aids Research: Individual fitting algorithms for digital hearing aids
No full textMeasurement of Acoustic Impedance of Porous Woven Hoses in Engine Intake Systems in the Presence of Mean Flow
No full textRate control using linear rate-rho model for H.264
No full textThe paper models relations of rate-rho and QP-rho, where rho is defined as the percentage of zero coefficients in a frame. These two models are used for a frame-level rate-control of H.264. A linear approximation scheme is adopted to model the rate-rho relations for the rate-control. The proposed frame-level rate-control method exploits rate-distortion optimization (RDO) to estimate macroblock modes and bitrates for the initial quantization parameter (QP). An intrarate model is also designed to determine an initial QP for the intra-frame. In experimental results, peak signal-to-noise ratio. bitrate estimation error, rate-control accuracy in the scene changes, and computational complexity of the proposed method are analyzed for various video sequences. According to the experimental analysis, the proposed method outperforms the existing rate-control method (Joint Video Team of ISO/IEC and ITV-T the Fifth Meeting, JVT-DO69, Geneva, Switzerland, 9-17 October 2002). (C) 2003 Elsevier B.V. All rights reserved
EFFICIENT MODIFIED JACOBI RELAXATION FOR MINIMIZING THE ENERGY FUNCTIONAL
No full textWe present an efficient scheme of diagonalizing large Hamiltonian matrices in a self-consistent manner. In the framework of the preconditioned conjugate gradient minimization of the energy functional, we replace the modified Jacobi relaxation for preconditioning and use for band-by-band minimization the restricted-block Davidson algorithm, in which only the previous wave functions and the relaxation vectors are included additionally for subspace diagonalization. Our scheme is found to be comparable with the preconditioned conjugate gradient method for both large ordered and disordered Si systems, while it is more rapidly converged for systems with transition-metal elements
A model for sound propagation in capillary ducts with mean flow
No full textA theoretical formulation is carried out of acoustic wave propagation in a narrow capillary tube with steady gas flow. The transverse variations of the particle velocity, temperature, and viscosity are considered. A fully developed laminar steady flow is assumed and the concept of a complex propagation constant is introduced in the formulation. The final equation form reduces to a Kummer-type differential equation and its solution is obtained in terms of confluent hypergeometric functions. The dispersion equation for the complex propagation constants takes on a recursive form. A simplified form of the analysis permits comparison with previous results dealing with visco-thermal effects and includes the features of Poiseuille-type laminar steady flow for low and medium shear wave numbers. Numerical simulation results show that the effect of steady flow is very significant for the backward traveling waves, and the assumption of a parabolic velocity profile for shear wave numbers less than four should be used carefully when the flow Mach number is greater than about 0.1. The present theory is applicable for shear wave numbers up to 10 or more, with the non-parabolic axial velocity fluctuations included, which encompasses almost all the possible practical situations of capillary duct dimension, temperature, and flow velocity. The theory would be useful as an approximation in solving the acoustic problems of the monolith in catalytic converters for automotive exhaust systems and of the propagation of sound in a porous medium (C) 1996 Academic Press Limite
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