35,750 research outputs found
Acoustic Echo and Noise Cancellation System for Hand-Free Telecommunication using Variable Step Size Algorithms
In this paper, acoustic echo cancellation with doubletalk detection system is implemented for a hand-free telecommunication system using Matlab. Here adaptive noise canceller with blind source separation (ANC-BSS) system is proposed to remove both background noise and far-end speaker echo signal in presence of double-talk. During the absence of double-talk, far-end speaker echo signal is cancelled by adaptive echo canceller. Both adaptive noise canceller and adaptive echo canceller are implemented using LMS, NLMS, VSLMS and VSNLMS algorithms. The normalized cross-correlation method is used for double-talk detection. VSNLMS has shown its superiority over all other algorithms both for double-talk and in absence of double-talk. During the absence of double-talk it shows its superiority in terms of increment in ERLE and decrement in misalignment. In presence of double-talk, it shows improvement in SNR of near-end speaker signal
Shell closure effects studied via cluster decay in heavy nuclei
The effects of shell closure in nuclei via the cluster decay is studied. In
this context, we have made use of the Preformed Cluster Model () of Gupta
and collaborators based on the Quantum Mechanical Fragmentation Theory. The key
point in the cluster radioactivity is that it involves the interplay of close
shell effects of parent and daughter. Small half life for a parent indicates
shell stabilized daughter and long half life indicates the stability of the
parent against the decay. In the cluster decay of trans lead nuclei observed so
far, the end product is doubly magic lead or its neighbors. With this in our
mind we have extended the idea of cluster radioactivity. We investigated decay
of different nuclei where Zirconium is always taken as a daughter nucleus,
which is very well known deformed nucleus. The branching ratio of cluster decay
and -decay is also studied for various nuclei, leading to magic or
almost doubly magic daughter nuclei. The calculated cluster decay half-life are
in well agreement with the observed data. First time a possibility of cluster
decay in nucleus is predicted
Solving large-scale dynamic systems using band Lanczos method in Rockwell NASTRAN on CRAY X-MP
The improved cost effectiveness using better models, more accurate and faster algorithms and large scale computing offers more representative dynamic analyses. The band Lanczos eigen-solution method was implemented in Rockwell's version of 1984 COSMIC-released NASTRAN finite element structural analysis computer program to effectively solve for structural vibration modes including those of large complex systems exceeding 10,000 degrees of freedom. The Lanczos vectors were re-orthogonalized locally using the Lanczos Method and globally using the modified Gram-Schmidt method for sweeping rigid-body modes and previously generated modes and Lanczos vectors. The truncated band matrix was solved for vibration frequencies and mode shapes using Givens rotations. Numerical examples are included to demonstrate the cost effectiveness and accuracy of the method as implemented in ROCKWELL NASTRAN. The CRAY version is based on RPK's COSMIC/NASTRAN. The band Lanczos method was more reliable and accurate and converged faster than the single vector Lanczos Method. The band Lanczos method was comparable to the subspace iteration method which was a block version of the inverse power method. However, the subspace matrix tended to be fully populated in the case of subspace iteration and not as sparse as a band matrix
Phases and properties of quark matter
I review recent developments in finite temperature lattice QCD which are
useful for the study of heavy-ion collisions. I pay particular attention to
studies of the equation of state and the light they throw on conformal symmetry
and the large N_c limit, and to the structure of the phase diagram for N_f=2+1.Comment: Plenary talk at Quark Matter 2008, Jaipur, India (8 pages, 5 figures
The Analysis of Thermal and Elastic Behaviour of Mixed Alkali Halide Systems Using Rydberg Potential
- …