Time stamped Digital Signature Scheme with Message Recovery & Its Application in E-Cash System

We propose a Timestamped signature scheme which can be verified universally using signer’s public parameters. A trusted third party, the Timestamping System provides timestamp to a signature without even knowing the content of the document. The proposed scheme can withstand active attacks, such as forgery attack and chosen cipher text attack. It also provides the message recovery feature, i.e., from the timestamped signature, the message can be recovered by the receiver. Hence, the message need not be sent with the signature. The suggested scheme do not require any hash function and there by reduces the verification cost as compared to existing schemes at the expense of marginal increase in signature generation cost. Further, the scheme is more secured as its security lies in solving three computationally hard assumptions Performance analysis of both the schemes has been carried out in details. We applied the Time-stamped signature scheme with Message recovery in Ecash syste

Spin-Hall effect in the scattering of structured light from plasmonic nanowire

Spin-orbit interactions are subwavelength phenomena which can potentially lead to numerous device related applications in nanophotonics. Here, we report Spin-Hall effect in the forward scattering of Hermite-Gaussian and Gaussian beams from a plasmonic nanowire. Asymmetric scattered radiation distribution was observed for circularly polarized beams. Asymmetry in the scattered radiation distribution changes the sign when the polarization handedness inverts. We found a significant enhancement in the Spin-Hall effect for Hermite-Gaussian beam as compared to Gaussian beam for constant input power. The difference between scattered powers perpendicular to the long axis of the plasmonic nanowire was used to quantify the enhancement. In addition to it, nodal line of HG beam acts as the marker for the Spin-Hall shift. Numerical calculations corroborate experimental observations and suggest that the Spin flow component of Poynting vector associated with the circular polarization is responsible for the Spin-Hall effect and its enhancement.Comment: Optics Letters (accepted), 201

Influence of lattice distortion on the Curie temperature and spin-phonon coupling in LaMn0.5_{0.5}Co0.5_{0.5}O3_{3}

Two distinct ferromagnetic phases of LaMn$_{0.5}$Co$_{0.5}$O$_{3}$ having monoclinic structure with distinct physical properties have been studied. The ferromagnetic ordering temperature $\textit{T}_{c}$ is found to be different for both the phases. The origin of such contrasting characteristics is assigned to the changes in the distance(s) and angle(s) between Mn - O - Co resulting from distortions observed from neutron diffraction studies. Investigations on the temperature dependent Raman spectroscopy provide evidence for such structural characteristics, which affects the exchange interaction. The difference in B-site ordering which is evident from the neutron diffraction is also responsible for the difference in $\textit{T}_{c}$. Raman scattering suggests the presence of spin-phonon coupling for both the phases around the $\textit{T}_{c}$. Electrical transport properties of both the phases have been investigated based on the lattice distortion.Comment: 9 figure

A Novel Neuro-Fuzzy Controller for Multilevel Renewable Energy System

Recently, Development and the utilization of single phase based multilevel inverters has been increased. This paper proposes concept based new topology based seven level inverter with less number of power electronics switches with utility grid connection. This proposed multilevel inverter operates with only eight power electronics switches at their fundamental frequency. This inverter produces seven level output from the input here we considered as a photovoltaic system. The cost, complexity, switching losses are small due to because of usage of less number of switches. The DC/DC converter receives input from which the three positive output voltages are generated and the multilevel inverter performs as a polarity reversal that provides both the positive and negative cycle output. For further enhancement in the output waveform, the filter circuit can be integrated in the output terminal of the multilevel inverter. This paper also proposed a concept of a neuro-fuzzy controller for controlling the seven level inverter. The simulation results are observed by means of MATLAB simulink toolbox

Designing an equalizer structure using gradient descent algorithms

In recent years, a growing field of research in “Adaptive Systems” has resulted in a variety of adaptive automatons whose characteristics in limited ways resemble certain behaviors of living systems and biological adaptive processes. The essential and principal property of the adaptive systems is its time-varying, self-adjusting performance by using a process called “learning” from its environment. A channel equalizer is a very good example of an adaptive system, which has been considered in this work to assess its performance with reference to various novel learning algorithms developed. The two main threats for the digital communication systems are Inter-symbol Interference (ISI) and the presence of noise in the channels which are both time varying. So, for rapidly varying channel characteristics, the equalizer too need to be adaptive. In order to combat with such problems various adaptive equalizers have been proposed. Particularly, when the decision boundary is highly nonlinear, the classical equalizers (so called linear ones) do not perform satisfactorily. The use of Artificial Neural Networks (ANNs) provides the required nonlinear decision boundary. The Back Propagation (BP) algorithm revolutionized the use of ANNs in diverse fields of science and engineering. The main problem with this algorithm is its slow rate of convergence. But the high speed digital communication systems, in the presence of rapidly fading channels, demand for faster training. To overcome this problem a faster method of training the neural network using RLS algorithm is proposed in this thesis work. But both the BP and RLS based BP algorithms belong to the family of Gradient-based algorithms, which have the inherent problem of getting trapped in local minima. Since obtaining a global solution is the main criterion for any adaptive system, an efficient search technique is highly desirable. Tabu Search serves this purpose

EFFECT OF EFFERVESCENCE IN COMBINATION WITH SUPERDISINTEGRANTS IN THE FORMULATION OF PROPRANOLOL HCL ORAL DISINTEGRATING TABLETS

ABSTRACTObjective: The current research work is intended to formulate propranolol HCl (PLH) as orally disintegrating tablet (ODT). It is also intending to checkthe superiority in a combination of superdisintegrants and effervescent mixture than the use of superdisintegrants alone by a direct compressiontechnique. To fasten the onset of action and thereby enhancing the bioavailability of PLH in comparison to its conventional tablets.Methods: Standard calibration curve of PLH was obtained in pH 6.8 phosphate buffer by spectrophotometric method, drug-excipient compatibilitystudies were carried by Fourier transform infrared (FT-IR) studies. All the formulations were evaluated for pre and postcompression studies.Accelerated stability studies were carried out up to 6 months for the optimized formulation, EF3.Results and Discussion: Superdisintegrants used in the study are compatible with PLH. Pre- and post-compression parameters were within theacceptable limits for all formulations. In vitro dissolution kinetic studies indicate the release of PLH from ODT increases as the concentration ofsuperdisintegrants as well as the ratio of citric acid: NaHCO3 of effervescent mixture increases. Formulations with an effervescent mixture are havingrapid disintegration and dissolution rate when compared to the formulations with superdisintegrants alone. The order of superdisintegrants inenhancing the dissolution rate of PLH is crospovidone (CPV) > croscarmellose sodium (CCS) > sodium starch glycolate (SSG). Formulation, EF3 (10%CPV and 1:3, citric acid: NaHCO3 ratio, respectively) had the highest dissolution efficiency at 10 minutes (DE10=82.74%); the first order dissolutionrate constant (K1=0.141/minutes) with a regression coefficient (r2=0.974) and lesser time for 90% of drug release (t90=4 minutes), was considered asthe optimal ODT in this study. Formulation EF3, passed the test for stability.Conclusion: Hence, an effective PLH ODT was formulated by the direct compression technique with disintegration by combination of superdisintegrantsand effervescent mixture, will fasten the onset of action and enhances the bioavailability of PLH in comparison to its conventional tablets.Keywords: Propranolol HCl, Orally disintegrating tablet, Sodium starch glycolate, Croscarmellose sodium, Crospovidone, Direct compression, In vitrodissolution studies

Review on Sparse-Based Multipath Estimation and Mitigation: Intense Solution to Counteract the Effects in Software GPS Receivers

Multipath is the major concern in GPS receivers that fade the actual GPS signal causes positioning error up to 10 m so special care need to be taken to mitigate the multipath effects. Numerous methods like hardware based antenna arrays technique, receiver based narrow correlator receiver, double -delta discriminator, Adaptive Multipath Estimator, Wavelet Transformation and Particle filter, Kalman filter based post receiver methods etc. used to resolve the problem. But some of the methods can only reduce code multipath error but not effective in eliminating carrier multipath error. Most of these techniques are based on the assumption that the Line-of-Sight (LOS) signal is stronger than the Non-Line of-Sight (NLOS) signals. However, in the scenarios where the LOS signal is weaker than the composite multipath signal, this approach may result in a bias in code tracking. In this chapter, different types of multipath mitigation and its limitation are described. The recent development in sparse signal processing based blind channel estimation is investigated to compensate the multipath error. The Rayleigh and Rician fading model with different multipath parameters are simulated to test the urban scenario. The inverse problem of finding the GPS signal is addressed based on the deconvolution approach. To solve linear inverse problems, the suitable kind of appropriate objective function has been formulated to find the signal of interest. By exploiting this methods, the signal is observed and the carrier and code tracking loop parameters are computed with minimal error