An analysis is presented of parametric instability in a finite-length rotating cylinder subject to periodic axial compression by small sinusoidal oscillations of one of its ends (the ‘piston’). The instability is due to resonant interactions between inertialwave (Kelvin) modes of the cylinder and the oscillatory compression and is resisted by viscosity, acting both through thin boundary layers ...

OBJECTIVE To discover design principles underlying the optimal waveforms for external chest and abdominal compression and decompression during cardiac arrest and cardiopulmonary resuscitation (CPR). METHOD A 14-compartment mathematical model of the human cardiopulmonary system is used to test successive generations of randomly mutated external compression waveforms during cardiac arrest and r...

Because of the explosively increasing information of image and video in various storage devices and Internet, the image and video compression technique becomes more and more important. This paper introduces the basic concept of data compression which is applied to modern image and video compression techniques such as JPEG, MPEG, MPEG-4 and so on. The basic idea of data compression is to reduce ...

This paper proposes a new harmonic wavelet transform (HWT) based on Discrete Cosine Transform (DCTHWT) and its application for signal or image compression and subband spectral estimation using Modified Group Delay (MGD). Further, the existing DFTHWT has also been explored for image compression. The DCTHWT provides better quality decomposed decimated signals, which enable improved compression an...

OBJECTIVE To explore in detail the expected magnitude of systemic perfusion pressure during standard CPR as a function of compression frequency for different sized people from neonate to adult. METHOD A 7-compartment mathematical model of the human cardiopulmonary system - upgraded to include inertance of blood columns in the aorta and vena cavae - was exercised with parameters scaled to refl...

SAR images are different from optical images in many ways. Therefore, the traditional compression methods, which have been used for compression, are not so efficient for the compression of the SAR images. Generally, 2-dimensional Fourier transform (2D-FT) is used for representing a complex SAR image. But the energy of the coefficients of 2D-FT on the complex SAR image distributes in the whole f...

To determine the effects of hearing loss and fast-acting compression on auditory grouping based on across-frequency modulation, modulation detection interference (MDI) was measured in listeners with normal hearing and hearing loss. MDI, the increase in the amplitude-modulation detection threshold of a target presented with an interferer distant in frequency, was measured using a 500-Hz target a...

PURPOSE In this study, the authors evaluated the effect of frequency compression hearing aids on speech perception ability and the time course and magnitude of acclimatization-related changes. METHOD Participants included children ages 11-18 years. Speech perception ability was evaluated over well-controlled baseline, treatment, and withdrawal study phases. Study-worn hearing aids were indivi...

A psychovisual experiment prescribes the quantization values in image compression. The quantization process is used as a threshold of the human visual system tolerance to reduce the amount of encoded transform coefficients. It is very challenging to generate an optimal quantization value based on the contribution of the transform coefficient at each frequency order. The psychovisual threshold r...

Frequency compression is an effective alternative to conventional hearing aids amplification for patients with severe-to-profound middleand high-frequency hearing loss and with some low-frequency residual hearing. In order to develop novel frequency compression strategy, it is important to first understand the mechanism for recognizing low-pass filtered speech, which simulates high-frequency he...