Flash floods need to be monitored from a safe place, ideally with noncontact instruments installed at a riverbank and oriented so that they look obliquely at the water surface. The “inclined Lidar” technique could be useful for this purpose. It works based on the fact that a near-infrared Lidar mounted with a large incidence angle can detect suspended particles slightly below the surface, provi...

Shape estimation of space debris, or the fragments of satellites and rocket bodies left on the earth’s orbit is an important task in evaluating its danger of a possible collision with operational spacecraft. A method of imaging a space debris whose size is smaller than the range resolution of the radar is proposed. It is called Single Range Doppler Interferometry (SRDI) in contrast to the conve...

The two 5GHz VLBI (Very Long Baseline Interferometry) observations (1996 June and 1997 November) presented in this paper, combined with several former VLBI observations at 8.4GHz and 5GHz, suggest that the radio flares of the blazar PKS 0420−014 can be divided into two classes according to their geometric origins in 5 or 8.4GHz VLBI maps and the properties of light curves. One class of flares, ...

A canonical space–time characterization of mobile wireless channels is introduced in terms of a fixed basis that is independent of the true channel parameters. The basis captures the essential degrees of freedom in the received signal using discrete multipath delays, Doppler shifts, and directions of arrival (DOA). The canonical representation provides a robust representation of the propagation...

This paper investigates the effects that the Doppler shift will theoretically have on a complex ultrasonic rangefinding system that utilizes a ring of concurrently operating sensors, using unique codes to reduce cross-talk between individual sensors. A methodology for selecting pseudorandom codes to maximize autocorrelation performance, maximize Doppler tolerance, and minimize cross-talk is pre...

Special relativistic eeects on the strength of the uorescent K iron line from black hole accretion disks. ABSTRACT The broad iron K emission line, commonly seen in the X-ray spectrum of Seyfert nuclei, is thought to originate when the inner accretion disk is illuminated by an active disk-corona. We show that relative motion between the disk and the X-ray emitting material can have an important ...

Meteorological data provides a rich source of imagery which is well suited to the growing eld of agent networks based image processing. Here we discuss one such system which analyses Doppler and reeec-tivity radar volumes to detect microbursts (windshear events). The system employs a network of agents, each performing a subtask of the detection, with message passing between agents. The various ...

We characterize the range of the attenuated and non-attenuated X-ray transform of compactly supported vector fields in the plane. The characterization is in terms of a Hilbert transform associated with the A-analytic functions à la Bukhgeim. As an application we determine necessary and sufficient conditions for the attenuated Doppler and X-ray data to be mistaken for each other.

HE 0141–3932 (zem = 1.80) is a bright blue radio-quite quasar with an unusually weak Lyα emission line. Large redshift differences (∆z = 0.05) are observed between high ionization and low ionization emission lines. Absorption systems identified at z abs = 1.78, 1.71, and 1.68 show mild oversolar metallicities (Z ≈ 1 − 2Z⊙) and can be attributed to the associated gas clouds ejected from the circ...

In this paper, we address the problem of multi-target detection and tracking over a network of separately located Doppler-shift measuring sensors. For this challenging problem, we propose to use the probability hypothesis density (PHD) filter and present two implementations of the PHD filter, namely the sequential Monte Carlo PHD (SMC-PHD) and the Gaussian mixture PHD (GM-PHD) filters. Performa...