Optical Fourier transform processing of radiotelescope visibility function data is reviewed. Emphasis is placed on the aspects of the processor design that arise from the unusual characteristics of the data. The complex visibility function is available only over a partially filled aperture consisting of a set of elliptical paths. It is recorded at the input to the optical processor on a carrier...

introduction in recent years methods based on radio frequency waves have been used for detecting breast cancer. using theses waves leads to better results in early detection of breast cancer comparing with conventional mammography which has been used during several years. materials and methods in this paper, a new method is introduced for detection of backscattered signals which are received by...

We investigate the characteristics of FIR brightness fluctuations at 90 μm and 170 μm in the Lockman Hole, which were surveyed with ISOPHOT aboard the Infrared Space Observatory (ISO). We first calculated the angular correlation function of each field and then its Fourier transform (the angular Power Spectral Density: PSD) over the spatial frequency range of f = 0.05–1 arcmin−1. The PSDs are fo...

Brightness functions were determined for the dark-adapted fovea and periphery. In one series of experiments, observers matched numbers to the brightness of a 1° white target at various intensities, presented half the time to the fovea, the other half to one of five peripheral loci: 5°, 12°, 20°, 35°, and (;0°. In a second series, observers matched the brightness of a 1°white target in the fovea...

Brightness values of pixels in an image are related to image irradiance by a non-linear function, called the radiometric response function. Recovery of this function is important since many algorithms in computer vision and image processing use image irradiance. Several investigators have described methods for recovery of the radiometric response, without using charts, from multiple exposures o...

Due to dynamic range compression and contrast enhancement realized simultaneously in traditional image enhancement algorithm based on frequency domain, which cause the low contrast degree, an improved image enhancement algorithm based on fuzzy filter is proposed in this paper. According to subjective feeling of the human visual system to light luminance, the image is processed with the global b...

We study the following question: if f is a nonzero measurable function on [ 0 , ∞ ) and m n are distinct nonnegative integers, does ratio ˆ / of Laplace transforms powers uniquely determine ? By inverse transform, answer yes or zero. Under some assumptions smoothness we show that in general case also affirmative. The question arose from problem economics, specifically auction theory, where cumu...

High speed photometry of the new AM CVn star in Hya (previously known as SN2003aw), spectroscopically identified by Chornock & Filippenko, shows it to have a superhump period of 2041.5 ± 0.3 s. We find a range of brightness from V ∼ 16.5 to 20.3, presumably caused by variations in the rate of mass transfer. In the intermediate state the system cycles in brightness with a period of ∼ 16 h and ra...