• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.12
• /
• pp.2328-2339
• /
• 1992

The propagation of coherent time-harmonic elastic L-and SV-waves is studied in a medium with random distribution of cylindrical inclusions. The purpose of the research is to characterize the dynamic elastic moduli and the attenuation properties of fiber-reinforced composite materials. The cylindes representing the fibers are assumed to be distributed in parallel with each other and the direction of incident waves are normal to the cylinder axes. A multiple scattering formula using the single scattering coefficients in conjunction with the Lax's quasicrystalline approximation is derived from which the dispersion relation for such medium is obtained. In order to formulate the multiple scattering interaction between cylinders, the pair correlation functions are generated by the Monte Carlo simulation technique. From the numerically evaluated complex wavenumbers, the propagation speed of the average wave, the coherent attenuation and the effective elastic moduli are presented as functions of frequency and fiber volume fraction.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.5
• /
• pp.11-19
• /
• 2014

In this paper, a low complexity parallel sphere decoder algorithm is proposed for high-order MIMO system. It reduces the computational complexity compared to the fixed-complexity sphere decoder (FSD) algorithm by static tree-pruning and dynamic tree-pruning using scalable node operators, and offers near-maximum likelihood decoding performance. Moreover, it also offers hardware-friendly node operation algorithm through fixing the variable computational complexity caused by the sequential nature of the conventional SD algorithm. A Monte Carlo simulation shows our proposed algorithm decreases the average number of expanded nodes by 55% with only 6.3% increase of the normalized decoding time compared to a full parallelized FSD algorithm for high-order MIMO communication system with 16 QAM modulation.

• Geomechanics and Engineering
• /
• v.20 no.1
• /
• pp.43-54
• /
• 2020

The limit analysis and response surfaces method were combined to investigate the reliability of pressurized tunnel faces subjected to seismic force. The quasi-static method was utilized to introduce seismic force into the tunnel face. A 3D horn failure mechanism of pressurized tunnel faces subjected to seismic force was constructed. The collapse pressure of pressurized tunnel faces was solved by the kinematical approach. The limit state equation of pressurized tunnel faces was obtained according to the collapse pressure and support pressure. And then a reliability model of pressurized tunnel faces was established. The feasibility and superiority of the response surfaces method was verified by comparing with the Monte Carlo method. The influence of the mean of soil parameters and support pressure, variation coefficients, distribution type and correlation of c-φ on the reliability of pressurized tunnel faces was discussed. The reasonable safety factor and support pressure required by pressurized tunnel faces to satisfy 3 safety levels were presented. In addition, the effects of horizontal seismic force, vertical seismic force and correlation of k_h-k_v on the reliability of pressurized tunnel faces were also performed. The method of this work can give a new idea for anti-seismic design of pressurized tunnel faces.