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The effective detection and tracking of low, small and slow targets is a current hot issue in the radar field. The paper is a sequel to radar weak target detection based on RFT and AMF fusion focus, and concentrates on the tracking of typical UAVs by pulse Doppler radar. The implementations of tracking algorithm mainly include: first, the preprocessing of the plots centroid processing and the multi-frame acceleration estimation has been applied. Then the labeled multi-Bernoulli (LMB) smoother is used for the multi-target tracking. Finally, the final trajectories of targets are output after trajectory continuity judgment and effective trajectory extraction. The LMB smoother can output the smoothed trajectories of targets, therefore, improving the estimation accuracy of distance and velocity. Trajectory continuity judgment and effective track extraction can effectively overcome the problems of breaking trajectory caused by velocity jitter and false trajectory caused by velocity ambiguity. The comprehensive score rate to process multiple test data is 96.67%, which verifies the effectiveness and robustness of the proposed tracking algorithm.

The use of electronically steered antennas in the azimuth dimension typically leads to a staircase-like antenna beam steering law in the Terrain Observation by Progressive Scan (TOPS) wide-swath synthetic aperture radar (SAR) data acquisition mode, which will introduce paired echoes in the focused images. This paper proposes a new approach for removing such paired echoes from TOPS SAR images based on the generalization of the ideal optimum filtering concept, which can be implemented easily in the SAR data processing. Modeling the amplitude-modulated azimuth signal shows that the absolute phase of the introduced paired echoes cannot be determined due to the random rotation angle jump time for each target, which will prevent the precise use of optimum filtering. An extended optimum filtering approach, which is originally proposed for suppressing the azimuth ambiguities in SAR images, is reintroduced in this particular case, and a new approximated and generalized form of the deconvolving filtering in the approach is redefined to accommodate the undetermined phase for both the strongest paired distortion peaks and the other peripheral peaks in the distorted impulse response function (IRF). Simulated data from a TOPS SAR mode with staircase-like beam steering are used to verify the improvement in image quality by using the new method. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) are semiconductor nanoparticles with a diameter of less than 10 nm, which have been widely used as fluorescent probes in biochemical analysis and vivo imaging because of their excellent optical properties. Sensitive and convenient detection of hepatitis B virus (HBV) gene mutations is important in clinical diagnosis. Therefore, we developed a sensitive, low-cost and convenient QDs-mediated fluorescent method for the detection of HBV gene mutations in real serum samples from chronic hepatitis B (CHB) patients who had received lamivudine or telbivudine antiviral therapy. We also evaluated the efficiency of this method for the detection of drug-resistant mutations compared with direct sequencing. In CHB, HBV DNA from the serum samples of patients with poor response or virological breakthrough can be hybridized to probes containing the M204I mutation to visualize fluorescence under fluorescence microscopy, where fluorescence intensity is related to the virus load, in our method. At present, the limits of the method used to detect HBV genetic variations by fluorescence quantum dots is 10³ IU/mL. These results show that QDs can be used as fluorescent probes to detect viral HBV DNA polymerase gene variation, and is a simple readout system without complex and expensive instruments, which provides an attractive platform for the detection of HBV M204I mutation.