A near-optimum detector with reduced out-of band response fornarrowband signals

Reduced spectral response in adjacent spectral bins is very desirable for detectors since it gives capability to detect narrowband signals in the presence of unknown interference and colored noise. Conventionally, this is achieved by applying a smoothing window on the signal at the cost of detection performance. In this correspondence, a new method of detecting narrowband signals that uses a close approximation to the matched filter and the extrapolated input signal is proposed. The filter used has a frequency response that is very closely equal to that of the matched filter within a Doppler bin and nearly zero response outside it     

Generalized form of optimal teleportation witnesses

We propose a generalized form of optimal teleportation witness to demonstrate their importance in experimental detection of the larger set of entangled states useful for teleportation in higher dimensional systems. The interesting properties of our witness reveal that teleportation witness can be used to characterize mixed state entanglement using Schmidt numbers. Our results show that while every teleportation witness is also a entanglement witness, the converse is not true. Also, we show that a hermitian operator is a teleportation witness iff it is a decomposable entanglement witness. In addition, we analyze the practical significance of our study by decomposing our teleportation witness in terms of Pauli and Gell-Mann matrices, which are experimentally measurable quantities.     

Purification and identification of antioxidant peptide from black pomfret, <Emphasis Type=Italic>Parastromateus niger</Emphasis> (Bloch, 1975) viscera protein hydrolysate

To utilize fish waste, black pomfret, Parastromateus niger viscera was analysed for its proximate and amino acid composition followed by hydrolysis using various proteases to extract antioxidant peptide. Antioxidant activities of the crude hydrolysate was evaluated using DPPH (54%), metal chelating (78.6%) at a concentration of 1 mg/mL, whereas the reducing power assay was done with different concentration (0.5–2.5 mg/mL) and the activity also increased with increasing concentration (0.021–0.068). Furthermore, the hydrolysate was purified by diethylaminoethyl (DEAE) ion-exchange and Sephadex G-25 gel filtration chromatography. Finally, the purified peptide had a mass of 701.9 Da, and the amino acid sequence was identified as Ala-Met-Thr-Gly-Leu-Glu-Ala using electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Moreover, the protection ability of the peptide toward hydroxyl radical-induced oxidative DNA damage and inhibiting lipid peroxidation was evaluated and compared with natural antioxidant α-tocopherol.     

Dielectric properties of iron doped calcium copper titanate,CaCu<Subscript>3</Subscript>Ti<Subscript>3.9</Subscript>Fe<Subscript>0.1</Subscript>O<Subscript>12</Subscript> ceramic

Dielectric properties of iron doped CaCu₃Ti₄O₁₂ (CCTO), viz. CaCu₃Ti_3.9Fe_0.1O₁₂ (CCTFO) prepared by a novel semi-wet route have been investigated. X-ray diffraction of powder sintered at 900 °C show formation of single phase solid solution. Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of CuO rich phase at grain boundaries of CCTFO. Nature of dielectric relaxation observed above room temperature is studied using complex plane impedance analysis and modulus spectroscopy. It has been found that out of the two relaxations reported earlier above room temperature, one occurring at lower temperature is due to grainboundaries interfacial polarization.     

Some system design considerations for a high switching frequency PWM inverter

A sinusoidal PWM inverter is required to faithfully reproduce the control waveforms at the output with minimum distortion. This paper presents some design considerations for such an inverter. The choice of switching frequency is the main criterion which affects the output voltage harmonic distortion at high switching frequencies. This paper shows that there exists an optimum switching frequency above which the output harmonic distortion becomes more visible. The dead time generator circuit for a low cost inverter and effect of driver circuits on the output waveform are discussed. Experimental results from laboratory models are presented.