Bose-Einstein condensation (BEC) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system, and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum-statistical. The study of BEC in weakly interacting systems which can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

Bose-Einstein condensation in a gas of sodium atoms

Ab initio computations of effective exchange integrals for H–H, H–He–H and Mn2O2 complex: comparison of broken-symmetry approaches

An Introduction to Coupled Cluster Theory for Computational Chemists

Multiwavelets are a new addition to the body of wavelet theory. Realizable as matrix-valued filterbanks leading to wavelet bases, multiwavelets offer simultaneous orthogonality, symmetry, and short support, which is not possible with scalar two-channel wavelet systems. After reviewing this theory, we examine the use of multiwavelets in a filterbank setting for discrete-time signal and image processing. Multiwavelets differ from scalar wavelet systems in requiring two or more input streams to the multiwavelet filterbank. We describe two methods (repeated row and approximation/deapproximation) for obtaining such a vector input stream from a one-dimensional (1-D) signal. Algorithms for symmetric extension of signals at boundaries are then developed, and naturally integrated with approximation-based preprocessing. We describe an additional algorithm for multiwavelet processing of two-dimensional (2-D) signals, two rows at a time, and develop a new family of multiwavelets (the constrained pairs) that is well-suited to this approach. This suite of novel techniques is then applied to two basic signal processing problems, denoising via wavelet-shrinkage, and data compression. After developing the approach via model problems in one dimension, we apply multiwavelet processing to images, frequently obtaining performance superior to the comparable scalar wavelet transform.

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The application of multiwavelet filterbanks to image processing

2017 25th European Signal Processing Conference (EUSIPCO)

Describes the development of a technique for subband image coding called the symmetric extension method which utilizes the nature of a symmetrically extended image to achieve high quality coding. There are, however, some restrictions on the usable subband coding system. The development is done based on the property of a symmetrically extended signal in the analysis process to remove the restriction. The behavior of the sequence after two processes, filtering and decimation, is examined and formulated. The development extends the application area of the technique. >

A development of symmetric extension method for subband image coding

We have proposed a new numerical scheme for the non-Born–Oppenheimer density functional calculation based upon the Green function techniques within the GW approximation for evaluating molecular properties in the full quantum mechanical treatment. We numerically calculate the physical properties of the individual motion in a hydrogen molecule and a muon molecule by means of this method and discuss the isotope effect on the properties in relation to correlation effects. It is concluded that the GW approximation is work well not only for calculation of the electronic state but also for that of nuclear state.

A formulation and numerical approach to molecular systems by the Green function method without the Born–Oppenheimer approximation

A novel approach to wideband beamforming using FIR (finite impulse response) fan filters is presented. The method is based on two-dimensional filtering for the outputs of a linear array of sensors. To beamform in the broadside of the array, a symmetrical 90 degrees /n filter is employed. The filter in which the angle of fan is more acute can form the narrower beam over the full band while the order of the filter becomes higher. To beamform in the direction along the array, an asymmetrical 45 degrees fan filter is used. As aliasing occurs in this beamforming, the band which is available is limited a little in width. A general implementation of the FIR fan filter beamformer is given as the parallel connection of one-dimensional FIR filters. >

Wideband beamforming using fan filter

The single-particle and collective dynamics of hydrogen/deuterium molecules in solid hcp para-hydrogen (p-H2) and ortho-deuterium (o-D2) has been investigated by using the path integral centroid molecular dynamics (CMD) simulations at zero-pressure and 5.4 and 5.0 K, respectively. For this purpose, we have newly unified the standard CMD method with the Parrinello–Rahman–Nose–Hoover-chain-type isothermal–isobaric technique. The phonon density of states have been obtained and the dynamic structure factors have been calculated to observe the phonon dispersion relations of both crystals. For solid p-H2, the high energy edge of the phonon energies of solid p-H2 is >13 meV, and the calculated phonon energies are significantly higher than those observed in Nielsen’s previous neutron scattering experiments in the energy region >9 meV. The relationship between the present results and the data reported so far is discussed to resolve the outstanding controversy regarding the phonon energies in solid p-H2. On the other hand, the excitation energies for solid o-D2 are in fairly good agreement with those of the neutron experiments. The calculated isothermal compressibility of solid p-H2 is found to be very close to the experimental result.

Molecular collective dynamics in solid para-hydrogen and ortho-deuterium: The Parrinello–Rahman-type path integral centroid molecular dynamics approach

This paper proposes an adaptive least mean square (LMS) algorithm that can he pipelined and has an efficient architecture for hardware implementation. The proposed algorithm shows the possibility of having LMS algorithms perform pipelined processing without degrading the convergence characteristics. An architecture based on the proposed algorithm is considered.

Kiyoshi Nishikawa

Papers

A development of symmetric extension method for subband image coding

A formulation and numerical approach to molecular systems by the Green function method without the Born–Oppenheimer approximation

Wideband beamforming using fan filter

Molecular collective dynamics in solid para-hydrogen and ortho-deuterium: The Parrinello–Rahman-type path integral centroid molecular dynamics approach

Pipelined LMS adaptive filter using a new look-ahead transformation