OTHR Impulsive Interference Suppression in Strong Clutter Background
External interferences can severely degrade the performance of an Over-the-horizon radar (OTHR), so suppression of external interferences in strong clutter environment is the prerequisite for the target detection. The traditional suppression solutions usually began with clutter suppression in either time or frequency domain, followed by the interference detection and suppression. Based on this traditional solution, this paper proposes a method characterized by joint clutter suppression and interference detection: by analyzing eigenvalues in a short-time moving window centered at different time position, clutter is suppressed by discarding the maximum three eigenvalues at every time position and meanwhile detection is achieved by analyzing the remained eigenvalues at different position. Then, restoration is achieved by forward-backward linear prediction using interference-free data surrounding the interference position. In the numeric computation, the eigenvalue decomposition (EVD) is replaced by singular values decomposition (SVD) based on the equivalence of these two processing. Data processing and experimental results show its efficiency of noise floor falling down about 10-20dB.
Adaptive HF-communication interference mitigation in HF-GWR
The high-frequency (HF)-communication interference in the HF ground wave radar (GWR) has the characteristics of high intensity, directivity, transient and homogeneity in its effects on all the rangecells of the HF-GWR, an adaptive HF-communication interference mitigation scheme based on those characteristics is proposed in this paper. The scheme uses the samples from the rangecells without echoes of the sea-surface to estimate the covariance matrix, then HF-communication interference is suppressed through the adaptive beamforming technique. By employing the measured data, the results show that the proposed sehme is effective in HF-communication interference mitigation.
Antimicrobial activity in pulp extract of Neem(Azadirachta indica Linn.)
Antimicrobialactivityin leaf extract of neem ( Azadirachta indica ) against human pathogenic bacteria. E.coli, Staphylococcus aureus, Pseudomonas aeruginosa , Salmonella typhimurium, Bacillus pumilus. Antimicrobia l activities of alcoholic extracts of neem leaves were used. Varying concent ration of each extracts 200mg/ml, 150 mg/ ml,100mg/ml, 50mg/ml, 25mg/ml prepared by using disc diffusion method. When compared with gentamycin 200mg and gentamycin 10mg, the methanol and ethanol extract shows maximum inhibition on Bacillus pumillus, Pseudomonas aeruginosa and Staphylococcus aureusin an asending order.