Stochastic resonance with different periodic forces in overdamped two coupled anharmonic oscillators

We study the stochastic resonance phenomenon in the overdamped two coupled anharmonic oscillators with Gaussian noise and driven by different external periodic forces. We consider (i) sine, (ii) square, (iii) symmetric saw-tooth, (iv) asymmetric saw-tooth, (v) modulus of sine and (vi) rectified sinusoidal forces. The external periodic forces and Gaussian noise term are added to one of the two state variables of the system. The effect of each force is studied separately. In the absence of noise term, when the amplitude $f$ of the applied periodic force is varied cross-well motion is realized above a critical value ($f_{\mathrm{c}}$) of $f$. This is found for all the forces except the modulus of sine and rectified sinusoidal forces.Stochastic resonance is observed in the presence of noise and periodic forces. The effect of different forces is compared. The logarithmic plot of mean residence time $\tau_{\mathrm{MR}}$ against $1/(D - D_{\mathrm{c}})$ where $D$ is the intensity of the noise and $D_{\mathrm{c}}$ is the value of $D$ at which cross-well motion is initiated shows a sharp knee-like structure for all the forces. Signal-to-noise ratio is found to be maximum at the noise intensity $D=D_{\mathrm{max}}$ at which mean residence time is half of the period of the driving force for the forces such as sine, square, symmetric saw-tooth and asymmetric saw-tooth waves. With modulus of sine wave and rectified sine wave, the $SNR$ peaks at a value of $D$ for which sum of $\tau_{MR}$ in two wells of the potential of the system is half of the period of the driving force. For the chosen values of $f$ and $\omega$, signal-to-noise ratio is found to be maximum for square wave while it is minimum for modulus of sine and rectified sinusoidal waves.Comment: 13 figures,27 page

Fast filter Based Noise Removal in Digital Images

Images play a major role in today’s world. It provides a lot of information in the field of medicine in diagnosing the disease, removing the defected area and also in traffic observations, surveillance systems, navigation etc. Often images are corrupted by noise due to various factors which cannot be avoided. Image denoising is done to detect the corrupted pixels and then correct them by the original pixel of the image. Filtering techniques are applied in images to filter out various types of noise. In this paper fast filters including mean, median, minimum, maximum, background subtraction are employed for removing the noise in images. ImageJ platform is employed for obtaining the results

Experimental evidence for vibrational resonance and enhanced signal transmission in Chua's circuit

We consider a single Chua's circuit and a system of a unidirectionally coupled n-Chua's circuits driven by a biharmonic signal with two widely different frequencies \omega and \Omega, where \Omega >> \omega. We show experimental evidence for vibrational resonance in the single Chua's circuit and undamped signal propagation of a low-frequency signal in the system of n-coupled Chua's circuits where only the first circuit is driven by the biharmonic signal. In the single circuit, we illustrate the mechanism of vibrational resonance and the influence of the biharmonic signal parameters on the resonance. In the n(= 75)-coupled Chua's circuits enhanced propagation of low-frequency signal is found to occur for a wide range of values of the amplitude of the high-frequency input signal and coupling parameter. The response amplitude of the ith circuit increases with i and attains a saturation. Moreover, the unidirectional coupling is found to act as a low-pass filter.Comment: 15 pages, 12 figures, Accepted for Publication in International Journal of Bifurcation and Chao

Control of chaos by nonfeedback methods in a simple electronic circuit system and the FitzHugh-Nagumo equation

Various control algorithms have been proposed in recent years to control chaotic systems. These methods are broadly classified into feedback and nonfeedback methods. In this paper, we make a critical analysis of nonfeedback methods such as (i) addition of constant bias, (ii) addition of second periodic force, (iii) addition of weak periodic pulse, and (iv) entrainment control. We apply these methods to a simple electronic circuit, namely, the Murali-Lakshmanan-Chua circuit system and FitzHugh-Nagumo equation. We make a comparative study of the various features associated with the algorithms

Efficient microwave synthesis of novel aromatic esters catalyzed by zirconia and its modified forms: a kinetic study

A series of solid acids such as ZrO2, 5% Mo(VI)/ZrO2, 10% Mo(VI)/ZrO2, 20% Mo(VI)/ZrO2 and SO42-/ZrO2 were prepared. These solid acids were characterized by BET, NH3-TPD/n-butylamine back titration, powder-XRD, FT-IR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ICP-OES techniques. The catalytic performance of these solid acids was evaluated in the synthesis of novel aromatic esters by the assistance of microwave irradiation and the catalytic activity of these solid acids was compared with pTsOH. The results clearly indicated that the zirconia based solid acids are efficient green catalysts for esterification reactions, which gave a maximum yield of the ester in a shorter reaction time and comparable catalytic activity of the pTsOH Bronsted acid. Kinetic studies were carried out to calculate the temperature coefficients (1.66 and 1.56) and energy of activation (66.82 kJ mol(-1) and 58.93 kJ mol(-1)) for SO42-/ZrO2 and pTsOH respectively. Pre-adsorption studies revealed that the reaction follows the Langmuir-Hinshelwood mechanism. The SO42-/ZrO2 solid acid catalyst was found to be reactivable and reusable

Determination of Letrozole in Tablet Formulations by Reversed Phase High Performance Liquid Chromatography

Purpose: To develop a simple, rapid, accurate and cost-effective reversed phase high performance liquid chromatography (RP-HPLC) method for letrozole in bulk and in tablets. Methods: Development of a method for the determination of letrozole, an anti-cancer drug, by RPHPLC was undertaken using a new mobile phase of acetonitrile:water (50:50, v/v). The eluent was monitored at 265 nm. Results: The optimized conditions developed showed a linear response from 160 to 240 μg/mL, with a correlation coefficient (R2) of 0.999. The limit of detection (LOD) and limit of quantification ( LOQ) were 136 and 160 μg/mL, respectively. The assay values for the two branded letrozole tablets tested were 99.2 and 100.2 %, respectively with % relative standard deviation (RSD) of 0.781 and 0.568, respectively. The bench top stability data of the drug in the mobile phase indicate that the drug was stable in the mobile phase for 24 h. Recovery data were good. Placebo study for specificity and interference of common excipients showed that the method was specific and free from interfering substances. Conclusion: Therefore, the fully validated method developed was sensitive enough to carry out routine analysis of letrozole in tablet formulations with regard to its run time, simplicity of sample preparation and accuracy.Key words: Letrozole, Assay, HPLC, Validation, Tablet formulation

Fabrication and hemocompatibility assessment of novel polyurethane-based bio-nanofibrous dressing loaded with honey and Carica papaya extract for the management of burn injuries

Management of burn injury is an onerous clinical task since it requires continuous monitoring and extensive usage of specialized facilities. Despite rapid improvizations and investments in burn management, >30% of victims hospitalized each year face severe morbidity and mortality. Excessive loss of body fluids, accumulation of exudate, and the development of septic shock are reported to be the main reasons for morbidity in burn victims. To assist burn wound management, a novel polyurethane (PU)-based bio-nanofibrous dressing loaded with honey (HN) and Carica papaya (PA) fruit extract was fabricated using a one-step electrospinning technique. The developed dressing material had a mean fiber diameter of 190±19.93 nm with pore sizes of 4-50 µm to support effective infiltration of nutrients and gas exchange. The successful blending of HN- and PA-based active biomolecules in PU was inferred through changes in surface chemistry. The blend subsequently increased the wettability (14%) and surface energy (24%) of the novel dressing. Ultimately, the presence of hydrophilic biomolecules and high porosity enhanced the water absorption ability of the PU-HN-PA nanofiber samples to 761.67% from 285.13% in PU. Furthermore, the ability of the bio-nanofibrous dressing to support specific protein adsorption (45%), delay thrombus formation, and reduce hemolysis demonstrated its nontoxic and compatible nature with the host tissues. In summary, the excellent physicochemical and hemocompatible properties of the developed PU-HN-PA dressing exhibit its potential in reducing the clinical complications associated with the treatment of burn injuries

An Efficient Resource Allocation Strategies in Cloud Computing

ABSTRACT: Recently cloud computing booming area and emerging trends in information communication technology domain. Resource allocation is to allocate the resource based on infrastructure as a service (IaaS) is one of the keys for large-scale Cloud applications. Therefore, performance evaluation of workload models and Cloud resource allocation and algorithms in a repeatable manner under different configurations and requirements is difficult. There is still lack of tools that enable developers to compare different resource allocation strategies in IaaS regarding both computing servers and user workloads. To fill this gap in tools for evaluation and modeling of Cloud environments and applications, we propose Cloud computing environment can help developers identify and explore appropriate solutions considering different resource allocation stratigies. we proposed for resource allocation strategies in cloud computing environment such as Cloud data centers, and results by applying the proposed system are analyzed and discussed