羟氨苄青霉素引起大疱性类天疱疮样疹

Robust small target detection of low signal-to-noise ratio (SNR) is very important in infrared search and track applications for self-defense or attacks. Consequently, an effective small target detection algorithm inspired by the contrast mechanism of human vision system and derived kernel model is presented in this paper. At the first stage, the local contrast map of the input image is obtained using the proposed local contrast measure which measures the dissimilarity between the current location and its neighborhoods. In this way, target signal enhancement and background clutter suppression are achieved simultaneously. At the second stage, an adaptive threshold is adopted to segment the target. The experiments on two sequences have validated the detection capability of the proposed target detection method. Experimental evaluation results show that our method is simple and effective with respect to detection accuracy. In particular, the proposed method can improve the SNR of the image significantly.

A Local Contrast Method for Small Infrared Target Detection

Unmanned aerial vehicle (UAV) communication is anticipated to be widely applied in the forthcoming fifth-generation wireless networks, due to its many advantages such as low cost, high mobility, and on-demand deployment. However, the broadcast and line-of-sight nature of air-to-ground wireless channels give rise to a new challenge on how to realize secure UAV communications with the destined nodes on the ground. This paper aims to tackle this challenge by applying the physical layer security technique. We consider both the downlink and uplink UAV communications with a ground node, namely, UAV-to-ground (U2G) and ground-to-UAV (G2U) communications, respectively, subject to a potential eavesdropper on the ground. In contrast to the existing literature on the wireless physical layer security only with the ground nodes at fixed or quasi-static locations, we exploit the high mobility of the UAV to proactively establish favorable and degraded channels for the legitimate and eavesdropping links, through its trajectory design. We formulate new problems to maximize the average secrecy rates of the U2G and G2U transmissions, by jointly optimizing the UAV’s trajectory, and the transmit power of the legitimate transmitter over a given flight period of the UAV. Although the formulated problems are non-convex, we propose iterative algorithms to solve them efficiently by applying the block coordinate descent and successive convex optimization methods. Specifically, both the transmit power and UAV trajectory are optimized, with the other being fixed in an alternating manner, until the algorithms converge. The simulation results show that the proposed algorithms can improve the secrecy rates for both U2G and G2U communications, as compared to other benchmark schemes without power control and/or trajectory optimization.

Securing UAV Communications via Joint Trajectory and Power Control

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Modern Operating Systems

Radar waveform diversity has received considerable attention in recent years due to increasing spectral congestion and the burgeoning capabilities of digital waveform generation. The promise of waveform diversity is far greater utilization of available degrees of freedom to enhance sensing performance and to even facilitate new operating modes. This tutorial provides an overview of this very broad topic, from the basic principles upon which it is founded to the myriad different areas being explored in research for practical sensing applications.

Overview of radar waveform diversity

This paper compares two algorithms for three-dimensional target localization from passive radar measurements. The algorithms use bistatic range measurements from multiple transmitter-receiver pairs to calculate the target position. The algorithms derived are based on the methods known for time-difference-of-arrival (TDOA) systems, namely spherical interpolation (SI) and spherical intersection (SX). Both algorithms rely on closed-form equations. A theoretical accuracy analysis of the algorithms is provided. This analysis is verified with Monte-Carlo simulations and a real-life example is presented.

Two Methods for Target Localization in Multistatic Passive Radar

The paper presents a family of passive coherent location (PCL) radar demonstrators, called PaRaDe (passive radar demonstrator), which were developed at Warsaw University of Technology. The systems exploit commercial FM radio transmitters as illuminators of opportunity in order to detect and track airborne targets. In the paper, the details of demonstrator systems are described and the results obtained in tests are presented.

PaRaDe - PAssive RAdar DEmonstrator family development at Warsaw University of Technology

This study presents an analysis of the detection range of a passive bistatic radar (PBR) by using FM radio transmitters as the illuminators of opportunity and the analysis of a required analogue-front-end dynamic range. Firstly, the theoretical considerations are presented in which the power budget is analysed, by taking into account the specific features of the PBR such as instantaneous reception of the direct illumination signal and weak target echoes and direct path interference removal. In the second part of this study, measurements performed by using an FM-based PBR demonstrator PaRaDe (passive radar demonstrator) are presented. The PaRaDe is a deployable system operating in real time, developed at the Warsaw University of Technology, Poland. The measurements include a scan of a typical spectrum in the range of 88-108 MHz, and the analysis of the long range detection of the air targets.

Analysis of detection range of FM-based passive radar

The paper presents digital beamforming for Passive Coherent Location (PCL) radar. The considered circular antenna array is a part of a passive system developed at Warsaw University of Technology. The system is based on FM radio transmitters. The array consists of eight half-wave dipoles arranged in a circular array covering 360deg with multiple beams. The digital beamforming procedure is presented, including mutual coupling correction and antenna pattern optimization. The results of field calibration and measurements are also shown.

Digital beamforming for Passive Coherent Location radar

A new approach to the passive coherent location (PCL) signal processing technique dedicated for use on mobile radar platforms is presented. The main goal of the research conducted was to present different aspects of an efficient space-time ground moving target indication (GMTI) algorithm for PCL radar mounted to airborne platforms. The algorithm described, based on displacement phase center antenna (DPCA), has been successfully tested with simulated and real-life data collected with an airborne passive radar demonstrator (PaRaDe).

Mateusz Malanowski

Papers

Two Methods for Target Localization in Multistatic Passive Radar

PaRaDe - PAssive RAdar DEmonstrator family development at Warsaw University of Technology

Analysis of detection range of FM-based passive radar

Digital beamforming for Passive Coherent Location radar

DPCA Detection of Moving Targets in Airborne Passive Radar