For auditory imaging, a bat emits orientation sounds (pulses) and listens to echoes. The parameters characterizing a pulse-echo pair each convey particular types of biosonar information. For example, a Doppler shift (a difference in frequency between an emitted pulse and its echo) carries velocity information. For a 61-kHz sound, a 1.0-kHz Doppler shift corresponds to 2.8 ms-1 velocity. The del...

This paper addresses the issue of employing space-time adaptive processing (STAP) prior to doppler filtering in radar systems. When STAP beamformer processing is applied to spatial/temporal samples that include successive radar pulses, the adaptive weights can cause modulation (spreading) of the desired target doppler. In this paper, a linearly constrained adaptive beamformer is proposed that e...

In this paper, we presented a track-before-detect (TBD) method which can cope with range-Doppler ambiguity for medium pulse repetition frequency (MPRF) radars. The target state evolutions in the ambiguous range-Doppler domain are considered as a hybrid system with the range-Doppler ambiguous number deemed as mode variable. Phase information of measurement is used to provide a detection sensitiv...

Introduction Weather radars are commonly employed for detection and ranging of precipitation, but radars with Doppler capability can also provide detailed information on the wind associated with (severe) weather phenomena. The Royal Netherlands Meteorological Institute (KNMI) operates two identical C-band (5.6 Ghz) Doppler weather radars. One radar is located in De Bilt and the other one is loc...

Because US plays a key role in the initial evaluation of hepatic hemangiomas, knowledge of the entire spectrum of US appearances of these tumors is important. Most hemangiomas have a distinctive US appearance, and even with those with atypical appearances on conventional gray-scale US, specific diagnoses can be made using pulse-inversion harmonic US with contrast agents. In this essay, we revie...

INTRODUCTION Fluid administration is a first-line therapy for acute kidney injury associated with circulatory failure. Although aimed at increasing renal perfusion in these patients, this intervention may improve systemic hemodynamics without necessarily ameliorating intrarenal flow distribution or urine output. We used Doppler techniques to investigate the effects of fluid administration on in...