Modified Fast ICA for Blind Signal separation

The Fast ICA or fixed-point algorithm is one of the most widely known algorithm for Blind Signal Separation (BSS) in terms of accuracy speed and computational complexity. Two versions of the algorithm are made available in literature: a one unit (deflation) algorithm and a symmetric algorithm. Both algorithms provide four standard contrast functions namely Skew, Pow3, Gauss and Tanh for selection to have better performance. In general, the selection of the contrast function depends on the data and the application. In Biomedical applications Electro Cardio Graph (ECG) data is problematic due to heart rate variation and several interferences such as muscle activity, respiration , thermal/electronic noise and noise from electrode-skin contact that corrupt the signal. We propose modified Fast ICA algorithm employing different data-adaptive contrast functions that are obtained from the underlying pdf of source signal distribution. We test the performance of modified Fast ICA algorithm for ECG application ECG data set is simulated and then added with four different types of noise distributions, white Gaussian, Flicker, Impulse and Rayleigh. We compare performance across the standard contrast functions in Fast ICA and modified Fast ICA using Signal Mean Square Error (SMSE) and Signal Noise Ratio (SNR) of estimated sources.. We show that the performance of modified Fast ICA is superior to standard contrasts in case of noisy ECG data

Electrical and Magnetic behaviour of PrFeAsO0.8F0.2 superconductor

The superconducting and ground state samples of PrFeAsO0.8F0.2 and PrFeAsO have been synthesised via easy and versatile single step solid state reaction route. X-ray & Reitveld refine parameters of the synthesised samples are in good agreement to the earlier reported value of the structure. The ground state of the pristine compound (PrFeAsO) exhibited a metallic like step in resistivity below 150K followed by another step at 12K. The former is associated with the spin density wave (SDW) like ordering of Fe spins and later to the anomalous magnetic ordering for Pr moments. Both the resistivity anomalies are absent in case of superconducting PrFeAsO0.8F0.2 sample. Detailed high field (up to 12Tesla) electrical and magnetization measurements are carried out for superconducting PrFeAsO0.8F0.2 sample. The PrFeAsO0.8F0.2 exhibited superconducting onset (Tconset) at around 47K with Tc({\rho} =0) at 38K. Though the Tconset remains nearly invariant, the Tc({\rho} =0) is decreased with applied field, and the same is around 23K under applied field of 12Tesla. The upper critical field (Hc2) is estimated from the Ginzburg Landau equation (GL) fitting, which is found to be ~ 182Tesla. Critical current density (Jc) being calculated from high field isothermal magnetization (MH) loops with the help of Beans critical state model, is found to be of the order of 103 A/cm2. Summarily, the superconductivity characterization of single step synthesised PrFeAsO0.8F0.2 superconductor is presented.Comment: 15 Pages Text + Fig

ANALYSIS OF HIGH-SNR PERFORMANCE OF MIMO MULTI-CHANNEL BEAM FORMING IN DOUBLE-SCATTERING CHANNELS

ABSTRACT This Work investigates the symbol error rate (SER) performance of the multiple-input multiple-output (MIMO) multi-channel beam forming (MB) in the general double scattering channel. We derive an asymptotic expansion on the marginal eigen value distribution of the MIMO channel matrix, and apply the result to get an approximate expression on the average SER at high signal-tonoise ratio (SNR). Two parameters pertaining to the SER, i.e., the diversity gain and the array gain, are analyzed. Our results show that it suffices for the double scattering channel to have only limited scatterers, if the same diversity gain as the Rayleigh channel is desired; however, once the number of scatterers is below a certain level, the array gain in the double-scattering channel will vary with the SNR logarithmically

Short-Term Multi-Cell Dynamic Resource Allocation in Future Cellular Networks

ABSTRACT In future cellular system, it is becoming more challenging to optimize the radio resource management and maximize the system capacity whilst meeting the required quality of service from user's point of view. Traditional schemes have approached this problem mainly focusing on resources within a cell and to large extent ignoring effects of multi-cell architecture. For multi-cell systems employing intra-cell orthogonal communication channels, inter-cell interference mitigation techniques are expected to be one of the key radio resource management functions. In this paper, we propose a multi-cell coordinated and un-coordinated dynamic resource sharing algorithms and reuse techniques among base station/ relay station cells. The sub carrier allocation and power allocation are performed on the basic of sum-rate maximization, by considering the load over the cell (3-sector cell). The simulation results show the performance comparison between both coordinated and un-coordinated resource allocation schemes with different sum-rate maximization algorithms. KEYWORDS Sum-rate maximization, Coordinated radio resource allocation, Un-coordinated radio resource allocation, Multi-cell interference and Inter-cell interference

Enhanced Room Temperature Coefficient of Resistance and Magneto-resistance of Ag-added La0.7Ca0.3-xBaxMnO3 Composites

In this paper we report an enhanced temperature coefficient of resistance (TCR) close to room temperature in La0.7Ca0.3-xBaxMnO3 + Agy (x = 0.10, 0.15 and y = 0.0 to 0.40) (LCBMO+Ag) composite manganites. The observed enhancement of TCR is attributed to the grain growth and opening of new conducting channels in the composites. Ag addition has also been found to enhance intra-granular magneto-resistance. Inter-granular MR, however, is seen to decrease with Ag addition. The enhanced TCR and MR at / near room temperature open up the possibility of the use of such materials as infrared bolometric and magnetic field sensors respectively.Comment: 22 pages of Text + Figs:comments/suggestions([email protected]

Physical property characterization of single step synthesized NdFeAsO0.80F0.20 bulk 50K superconductor

We report an easy single step synthesis route of title compound NdFeAsO0.80F0.20 superconductor having bulk superconductivity below 50 K. The title compound is synthesized via solid-state reaction route by encapsulation in an evacuated (10-3 Torr) quartz tube. Rietveld analysis of powder X-ray diffraction data shows that compound crystallized in tetragonal structure with space group P4/nmm. R(T)H measurements showed superconductivity with Tc (R=0) at 48 K and a very high upper critical field (Hc2) of up to 345 Tesla. Magnetic measurements exhibited bulk superconductivity in terms of diamagnetic onset below 50 K. The lower critical field (Hc1) is around 1000 Oe at 5 K. In normal state i.e., above 60 K, the compound exhibited purely paramagnetic behavior and thus ruling out the presence of any ordered FeOx impurity in the matrix. In specific heat measurements a jump is observed in the vicinity of superconducting transition (Tc) along with an upturn at below T=4 K due to the AFM ordering of Nd+3 ions in the system. The Thermo-electric power (TEP) is negative down to Tc, thus indicating dominant carriers to be of n-type in NdFeAsO0.80F0.20 superconductor. The granularity of the bulk superconducting NdFeAsO0.8F0.2 sample is investigated and the intra and inter grain contributions have been individuated by looking at various amplitude and frequencies of the applied AC drive magnetic field.Comment: 26pages text + Figures: comments/suggestions welcome ([email protected] & http://www.freewebs.com/vpsawana