Simulation and Performance Evaluation of Shunt Hybrid Power Filter for Power Quality Improvement Using PQ Theory

This work proposes the design of shunt hybrid filter using instantaneous power theory to improve the power quality and simulation has been carried out for 3 phase distribution system feeding different types of non linear loads. The proposed filter consists of parallel combination of 5th and 7th tuned selective harmonic elimination passive filters, which is connected in series with a small rating IGBTs based voltage source inverter. In this work, principle of compensation and filtering behavior of the system has been discussed in detail. Instantaneous real and reactive power theory based controller has been designed to estimate the reference current from the distorted current. In order to reduce the harmonics, generated reference currents are tracked by voltage source inverter using hysteresis band current controller. The performance of the hybrid scheme is evaluated for various nonlinear loads using Matlab/ Simulink tool. The detailed analysis has been carried out on harmonics reduction and DC bus voltage regulation and the simulation result ensures the feasibility of suggested control strategy. The proposed topology improves the filtering performance of the passive filter in hybrid scheme

Highly efficient spin-orbit torque and switching of layered ferromagnet Fe3GeTe2

Among van der Waals (vdW) layered ferromagnets, Fe3GeTe2 (FGT) is an excellent candidate material to form FGT/heavy metal heterostructures for studying the effect of spin-orbit torques (SOT). Its metallicity, strong perpendicular magnetic anisotropy built in the single atomic layers, relatively high Curie temperature (Tc about 225 K) and electrostatic gate tunability offer a tantalizing possibility of achieving the ultimate high SOT limit in monolayer all-vdW nanodevices. The spin current generated in Pt exerts a damping-like SOT on FGT magnetization. At about 2.5x1011 A/m2 current density,SOT causes the FGT magnetization to switch, which is detected by the anomalous Hall effect of FGT. To quantify the SOT effect, we measure the second harmonic Hall responses as the applied magnetic field rotates the FGT magnetization in the plane. Our analysis shows that the SOT efficiency is comparable with that of the best heterostructures containing three-dimensional (3D) ferromagnetic metals and much larger than that of heterostructures containing 3D ferrimagnetic insulators. Such large efficiency is attributed to the atomically flat FGT/Pt interface, which demonstrates the great potential of exploiting vdW heterostructures for highly efficient spintronic nanodevices

Optimization of Culture Conditions for the Production of Extracellular Cellulase from Corynebacterium lipophiloflavum

Cellulolytic enzyme producing bacteria were isolated from decaying vegetables on nutrient agar plates. As many as fourteen different bacterial strains were isolated and they were screened for the production of cellulase enzyme on a medium containing carboxymethyl cellulose (0.5% w/v). A Congo red dye based qualitative assay was performed to identify cellulase producing bacteria isolated from the vegetables. Among the difference strains, after screening on CMC agar, one strain exhibited relatively higher cellulase activity and was identified as Cornybacterium lipophiloflavum by a bacteriologist. Culture conditions were optimized for the above bacterium in the production medium supplemented with different carbon and nitrogen sources, different pH and different concentrations of CMC. Glucose and yeast extract proved to be the suitable carbon and nitrogen sources while pH 7.0 was ideal for cellulase production by the bacterium. Carboxymethyl cellulose at 1% in the medium induced relatively higher cellulase activity. Electrophoretic analysis of the ammonium sulfate precipitated proteins showed three prominent bands and whose molecular masses were estimated as 60, 69 and 75 kDa.  Cellulase produced by Cornybacterium lipophiloflavum could efficiently remove dyes or inks from the pulp incubated either in the form of intact growing cell or with clarified supernatant. The enzyme also removed starch from the fabric incubated with culture supernatant suggesting the potential use of Cornybacterium lipophiloflavum cellulase in industrial applications

An Enhanced Least Significant Bit Steganography to Improve the Effectiveness of Graphical Password Authentication

Authentication means acknowledging a user’s identity. It is the way of associating a request with a set of identity. The identification provided is an authorized user’s information on a personal computer system or within an authentication server. A graphical password is a validation system in which user has to select from images, in a particular order, presented in a graphical user + interface (GUI). Graphical passwords can be easily remembered, as users remember images better than words. Also, the system should be more unaffected by brute-force attacks, because there is practically an infinite search space. Complex text passwords are hard to remember and simple textual passwords are easy to guess. Graphical passwords provide more robustness and memorability. It is a secure mechanism to provide authenticated sign up to a system

An Enhanced Least Significant Bit Steganography to Improve the Effectiveness of Graphical Password Authentication

Authentication means acknowledging a user’s identity. It is the way of associating a request with a set of identity. The identification provided is an authorized user’s information on a personal computer system or within an authentication server. A graphical password is a validation system in which user has to select from images, in a particular order, presented in a graphical user + interface (GUI). Graphical passwords can be easily remembered, as users remember images better than words. Also, the system should be more unaffected by brute-force attacks, because there is practically an infinite search space. Complex text passwords are hard to remember and simple textual passwords are easy to guess. Graphical passwords provide more robustness and memorability. It is a secure mechanism to provide authenticated sign up to a system

Zero Temperature Dynamics of 2D and 3D Ising Ferromagnets

We consider zero-temperature, stochastic Ising models with nearest-neighbor interactions in two and three dimensions. Using both symmetric and asymmetric initial configurations, we study the evolution of the system with time. We examine the issue of convergence of the dynamics and discuss the nature of the final state of the system. By determining a relation between the median number of spin flips per site, the probability p that a spin in the initial spin configuration takes the value +1, and lattice size, we conclude that in two and three dimensions, the system converges to a frozen (but not necessarily uniform) state when p is not equal to 1/2. Results for p=1/2 in three dimensions are consistent with the conjecture that the system does not evolve towards a fully frozen limiting state. Our simulations also uncover `striped' and `blinker' states first discussed by Spirin et al., and their statistical properties are investigated.Comment: 17 pages, 12 figure

OPTIMAL PIXEL ADJUSTMENT BASED REVERSIBLE STEGANOGRAPHY

A novel prediction-based reversible steganographic scheme based on image in-painting is used to embed the secret information. First, reference pixels are chosen adaptively according to the distribution characteristics of the image content. Then, the image in-painting technique based on partial differential equations (PDE) was introduced to generate a prediction image that has similar structural and geometric information as the cover image. Finally, by using the two selected groups of peak points and zero points, the histogram of the prediction error is shifted to embed the secret bits reversibly[1]. Since the same reference pixels can be exploited in the extraction procedure, the embedded secret bits can be extracted from the stego image correctly, and the restoration of the cover image is lossless. Through, the use of the adaptive strategy for choosing reference pixels and the in-painting predictor, the more embeddable pixels are acquired.However, PDE based in-painting algorithm is computationally complex and requires more execution time. Also, the quality of the stego image is not considered in the in-painting algorithm. To improve the visual quality of the stego image Optimal Pixel Adjustment algorithm (OPA) can be used. The OPA is applied after embedding the message. The frequency domain is employed to increase the robustness of the steganography method. OPA algorithm is to minimize the error difference between the original coefficient value and the altered value by checking the right next bit to the modified LSBs so that the resulted change will be minimal. This research work uses OPA to obtain an optimal mapping function to reduce the difference error between the cover and the stego-image which increases the hiding capacity with low distortions and Peak Signal to Noise Ratio (PSNR)

A 0.82V supply and 23.4 ppm/0C current mirror assisted bandgap reference

Traditional BGR circuits require a 1.05V supply due to the VBE of the BJT. Deep submicron CMOS technologies are limiting the supply voltage to less than 940mV. Hence there is a strong motivation to design them at lower supply voltages. The supply voltage limitation in conventional BGR is described qualitatively in this paper. Further, a current mirror-assisted technique has been proposed to enable BGR operational at 0.82V supply. A prototype was developed in 65nm TSMC CMOS technology and post-layout simulation results were performed. A self-bias opamp has been exploited to minimize the systematic offset. Proposed BGR targeted at 450mV works from 0.82-1.05V supply without having any degradation in the performance while keeping the integrated noise of 15.2µV and accuracy of 23.4ppm/0C. Further, the circuit consumes 21µW of power and occupies 73*32µm2 silicon area

Why Are Saccharides Dehydrated in the Presence of Electrolytes? Insights from Molecular Modeling and Thermodynamic Measurements

The mechanisms governing the interactions of neutral polar solutes with ions in aqueous solutions are still poorly understood, despite the importance of this phenomenon in many fields (chemistry, physicochemistry, biology, food industries). In order to go further through the understanding of the molecular mechanisms governing the ions’ specific effects, this paper presents a generic method dealing with the characterization and understanding of interactions between saccharides and ions in aqueous systems. For that, an original approach combining a computational technique and experimental measurements (thermodynamic properties) is proposed to explain and rationalize the relationship between the solute hydration and the physical chemistry of the ions in solution (cation/anion, charge, size, and hydration). These relationships make it possible to evaluate the hydration state of a saccharide, a polar neutral molecule, according to the ionic composition, from the knowledge of the ions’ hydration properties. This work proposes new insight into molecular mechanisms governing the polar neutral solute/ion interactions and a new understanding of the hydration phenomenon in electrolytic solutions

Checklist of Mosses (Bryophyta) of Bodamalai Hills in Eastern Ghats, Tamil Nadu

Bodamalai Hills, situated on the Southern Eastern Ghats of Tamil Nadu, were explored for mosses (bryophyta) for the first time. As a result a checklist of mosses has been prepared comprising 52 species belonging to 38 genera and 21 families. The dominant families with the maximum number of species are Pottiaceae, Bryaceae, Stereophyllaceae, Sematophyllaceae and Brachytheciaceae. The dominant genera are Brachymenium and Bryum and the dominant species are Barbula javanica and Bryum capillare