Designs of low delay cosine modulated filter banks and subband amplifiers

This paper proposes a design of a low delay cosine modu-lated filter bank and subband amplifier coefficients for digi-tal audio hearing aids denoising applications. The objective of the design is to minimize the delay of the filter bank. Speci-fications on the maximum magnitude of both the real and the imaginary parts of the transfer function distortion and the aliasing distortion of the filter bank are imposed. Also, the constraint on the maximum absolute difference between the desirable magnitude square response and the designed mag-nitude square response of the prototype filter over both the passband and the stopband is considered. The subband am-plifier coefficients are designed based on a least squares training approach. The average mean square errors between the noisy samples and the clean samples is minimized. Com-puter numerical simulation results show that our proposed approach could significantly improve the signal-to-noise ratio of digital audio hearing aids

Proposal of Direct Search for Strongly Bound States of ppbar, npbar Systems with High Intensity and Collective pbar beam

In this letter, we discuss the possibility to look for the direct evidence of the existence of the ppbar and npbar bound states. Measurement of the single \gamma ray from the ppbar and npbar systems at rest can directly confirm whether the X(1860) and X(1835) are the resonances which are strongly coupled to ppbar. In addition to the neutral candidate, a charged resonance $X^-$ is also proposed to be searched for in npbar channel. We find that the data from the Crystal Barrel experiment at LEAR/CERN can be used to confirm the X(1835) observed by BES Collaboration. The possibility of measuring the $\gamma$ spectrum below 100 MeV at the new experiment with cold high intensity \pbar beam at GSI is discussed. These new techniques can be used to probe the structure of the X(1860) and X(1835) in the future.Comment: Accepted by Mod. Phys. Lett.

Fluctuation and localization of the nonlinear Hall effect on a disordered lattice

The nonlinear Hall effect has recently attracted significant interest due to its potentials as a promising spectral tool and device applications. A theory of the nonlinear Hall effect on a disordered lattice is a crucial step towards explorations in realistic devices, but has not been addressed. We study the nonlinear Hall response on a lattice, which allows us to introduce disorder numerically and reveal a mechanism that was not discovered in the previous momentum-space theories. In the mechanism, disorder induces an increasing fluctuation of the nonlinear Hall conductance as the Fermi energy moves from the band edges to higher energies. This fluctuation is a surprise, because it is opposite to the disorder-free distribution of the Berry curvature. More importantly, the fluctuation may explain those unexpected observations in the recent experiments. We also discover an "Anderson localization" of the nonlinear Hall effect. This work shows an emergent territory of the nonlinear Hall effect yet to be explored