Search results for "impulse"

FIR Kramers–Kronig transformers for relaxation data conversion

2006

It is shown that relaxation data conversion by the Kramers-Kronig (KK) relations can be treated as a filtering problem of band-unlimited relaxation signals in the Mellin transform domain. Based on this concept, KK relations are implemented in the form of FIR filters with the logarithmic sampling. It is demonstrated that KK transformers have sampling rate dependent impulse and frequency responses and only calculation of the imaginary part from the real part can be implemented by a computationally realisable filter. The performance of different types of transformers is studied.Approximately inversely proportional relationship is established between the error and the frequency range of input s…

Automatic Detection and Characterization of Acoustic Plane-Wave Reflections Using Circular Microphone Arrays

2013

The spatial characteristics of the sound field inside a room can be meaningfully described by means of microphone array processing techniques. In this context, the set of impulse responses sampled by a microphone array can be seen as an image made of acoustic plane-wave footprints. Due to the circular geometry of the microphone array, these footprints have a cosine-like shape that can be fully described as a function of the direction of arrival (DOA) of the impinging plane wave. This paper proposes a Hough-transform-based approach to plane-wave detection in microphone array multi-trace impulse responses. Experiments using a set of real microphone recordings are described, showing the potent…

Reduction of spherical-aberration impact in microscopy by wavefront coding

2009

In modern high-NA optical scanning instruments, like scanning microscopes, the refractive-index mismatch between the sample and the immersion medium introduces a significant amount of spherical aberration when imaging deep inside the specimen, spreading out the impulse response. Since such aberration depends on the focalization depth, it is not possible to achieve a static global compensation for the whole 3D sample in scanning microscopy. Therefore a depth-variant impulse response is generated. Consequently, the design of pupil elements that increase the tolerance to this aberration is of great interest. In this paper we report a hybrid technique that provides a focal spot that remains alm…

2014

Disorders such as borderline personality disorder (BPD) or attention-deficit/hyperactivity disorder (ADHD) are characterized by impulsive behaviors. Impulsivity as used in clinical terms is very broadly defined and entails different categories including personality traits as well as different cognitive functions such as emotion regulation or interference resolution and impulse control. Impulse control as an executive function, however, is neither cognitively nor neurobehaviorally a unitary function. Recent findings from behavioral and cognitive neuroscience studies suggest related but dissociable components of impulse control along functional domains like selective attention, response selec…

High-speed, low-complexity fir filter using multiplier block reduction and polyphase decomposition

2005

In this paper we discuss the design and implementation of a highspeed FIR filter for both interpolation and decimation of the sample frequency. Several FIR filter structures are compared and various schemes for simplifying the implementation of the multiplications are evaluated. Carry-save adders with carryoverflow correction are used in the implementation. The results in terms of chip area and power consumption are compared using a standard 0.8 pm 3.3 V CMOS process.

Impulse noise removal on an embedded, low memory SIMD processor

2003

Vector median filters efficiently reduce noise while preserving image details. However, their high computational complexity for color images makes them impractical for real-time systems. We propose new computationally efficient filtering algorithms, called index mapping filters (IMF). These filtering algorithms are accelerated by implementing them on a massively data parallel processor array. In addition to greater computational efficiency, these algorithms result in robust noise reduction of corrupted color images. Analyses of mean square error, signal-to-noise-ratio, and visual comparison metrics indicate that IMF are competitive with the vector median filter (VMF) in their ability to cor…

Photoproduction of the hypertriton

1997

In the framework of the impulse approximation we study the photoproduction of the hypertriton $^3_{\Lambda}$H by using realistic $^3$He wave functions obtained as solutions of Faddeev equations with the Reid soft-core potential for different $^3_{\Lambda}$H wave functions. We obtain relatively small cross sections of the order of 1 nb. We also find that the influence of Fermi motion is important, while the effect of different off-shell assumptions on the cross section is not too significant.

Nuclear pion photoproduction in theΔresonance region

1999

A measurement of the /sup 12/C( gamma , pi /sup +/n)/sup 11/B reaction in quasifree pi -production kinematic regimes has been performed using tagged photons in conjunction with large solid angle pi and n detectors. The aim of the experiment was to investigate predicted modifications to the Delta excitation of nucleons and their subsequent propagation and decay, brought about by the nuclear medium. Differential cross sections are presented for photon energies spanning the Delta (1232) excitation region. The measurements are consistent with distorted wave impulse approximation calculations in which the amplitude for proton Delta excitation, followed by Delta propagation and decay to pi /sup +…

Quasi-elastic neutrino reaction in deuterium

1972

In this paper the processv+d→μ−+p+p is studied in the framework of the impulse approximation, with or without using closure approximation. Final-state interactions are considered.

Total muon-capture rate. Application to11B

1972

A study of the total muon-capture rate in nuclei is presented, with the aid of the impulse and closure approximations and under the assumption that the initial nucleus can be described by a mixing of states in theJ-scheme. The theory is applied to the process of muon capture in11B, with a discussion on the value of the average neutrino momentum.