Thickness dependent electronic structure of ultra-thin tetrahedral amorphous carbon (ta-C) films

Microstructural properties of ultrathin (1-10 nm) tetrahedral amorphous carbon (ta-C) films are investigated by Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, X-ray Photoelectron Spectroscopy, Raman spectroscopy and Atomic Force Microscopy (AFM). The CK-edge NEXAFS spectra of 1 nm ta-C films provided evidence of surface defects (C―H bonds) which rapidly diminish with increasing film thickness. A critical thickness for stabilization of largely sp³ matrix structure distorted by sp² sites is observed via the change of π*C═C peak behavior. Meanwhile, an increase in the film thickness promotes an enhancement in sp³ content, the film roughness remains nearly constant as probed by spectroscopic techniques and AFM, respectively. The effect of thickness on local bonding states of ultrathin ta-C films proves to be the limiting factor for their potential use in magnetic and optical storage devices.     

Dielectric relaxation, conductivity behaviour and magnetic properties of Mg substituted Ni-Li ferrites

The dielectric properties of Mg substituted Ni-Li spinel ferrites synthesized by sol-gel auto combustion process have been studied using impedance measurements in the frequency range from 10 Hz to 10 MHz and in the temperature range from 310 K to 473 K. The effect of frequency, temperature and composition on dielectric constant (?′), dielectric loss (tan δ) and conductivity (σ) has been discussed in terms of hopping of charge carriers between Fe²⁺ and Fe³⁺ ions. The electrical modulus formulism has been employed to study the relaxation dynamics of charge carriers and the results indicate the presence of non-Debye type of relaxation in the present ferrites. Similar values of activation energies for dc conduction (E_dc) and for conductivity relaxation (E_M″) reveal that the mechanisms of electrical conduction and dielectric polarization are same in these ferrites. A single ‘master curve’ for normalized plots of all the modulus isotherms observed for a given composition indicates the temperature independence of dynamical process for charge carriers. The saturation magnetization and coercivity have been calculated from the hysteresis loop measurements and show striking dependence on the composition.     

Solid Particle Erosion Behavior of WC-CoCr Nanostructured Coating

In the present study, solid particle erosion resistance of high-velocity oxy-fuel (HVOF)-sprayed WC-CoCr coatings was evaluated. Erosion testing was conducted using alumina (Al₂O₃) powder as the erodent with three different impact angles (30, 60, and 90°) and impact velocity was kept constant. The coatings were deposited using two different powders; one was composed of conventional WC particles and second one contained nanoscale particles mixed with CoCr binder material. Erosion testing was carried out at room temperature using an air-jet erosion test setup. The effect of varying impact angles was studied and discussed with the help of scanning electron microscopy images of worn surfaces of coatings. The results showed that coating properties like microhardness and fracture toughness have a strong influence on the erosion behavior. During erosion testing, material was removed by fracturing and pullout of WC grains from the binder matrix. The morphology of the eroded surface also showed cutting, lip, and groove formation in the binder matrix caused by the repetitive impacts of erodent particles. It was observed that coating with nano-WC grains exhibited higher erosion resistance compared to conventional coating.     

Motion Panoramas

In this paper we describe a method for analysing video sequences and for representing them as mosaics or panoramas. Previous work on video mosaicking essentially concentrated on static scenes. We generalize these approaches to the case of a rotating camera observing both static and moving objects where the static portions of the scene are not necessarily dominant, as it has been often hypothesized in the past. We start by describing a robust technique for accurately aligning a large number of video frames under unknown camera rotations and camera settings. The alignment technique combines a feature‐based method (initialization and refinement) with rough motion segmentation followed by a colour‐based direct method (final adjustment). This precise frame‐to‐frame alignment allows the dynamic building of a background representation as well as an efficient segmentation of each image such that moving regions of arbitrary shape and size are aligned with the static background. Thus a motion panorama visualizes both dynamic and static scene elements in a geometrically consistent way. Extensive experiments applied to archived videos of track‐and‐field events validate the approach. Copyright © 2004 John Wiley & Sons, Ltd.     

Cactus cladode polysaccharide as cryoprotectant in frozen Paneer (Indian Cottage Cheese)

The study investigated the optimisation of freezing conditions for Paneer (Indian cottage cheese) incorporated with cactus cladode polysaccharide as cryoprotectant. The freezing rate of both natural and commercial cryoprotectant‐containing samples varied significantly. The optimised (2% natural cryoprotectant) Paneer sample had about 44% moisture content, 14% protein, 16% carbohydrate and 22% fat. Freezing time of optimised Paneer sample packed in metalised polyester was 40 min. The study concluded that Paneer incorporated with 2% cactus cladode polysaccharide, packaged using metalised polyester and frozen with packaged immersion freezing method, had the least freezing time (40 min) and retained better texture during freezing.     

Analysis of Traffic Impact on Proposed Congestion Control Scheme in AODV

Wireless Personal Communications - Congestion is a noteworthy problem in Mobile Ad hoc Network, which occurs when number of users increases and a node carries data more than its capacity. In this...     

A perceptually motivated stationary wavelet packet filterbank using improved spectral over-subtraction for enhancement of speech in various noise environments

In this paper, we propose a speech enhancement method where the front-end decomposition of the input speech is performed by temporally processing using a filterbank. The proposed method incorporates a perceptually motivated stationary wavelet packet filterbank (PM-SWPFB) and an improved spectral over-subtraction (I-SOS) algorithm for the enhancement of speech in various noise environments. The stationary wavelet packet transform (SWPT) is a shift invariant transform. The PM-SWPFB is obtained by selecting the stationary wavelet packet tree in such a manner that it matches closely the non-linear resolution of the critical band structure of the psychoacoustic model. After the decomposition of the input speech, the I-SOS algorithm is applied in each subband, separately for the estimation of speech. The I-SOS uses a continuous noise estimation approach and estimate noise power from each subband without the need of explicit speech silence detection. The subband noise power is estimated and updated by adaptively smoothing the noisy signal power. The smoothing parameter in each subband is controlled by a function of the estimated signal-to-noise ratio (SNR). The performance of the proposed speech enhancement method is tested on speech signals degraded by various real-world noises. Using objective speech quality measures (SNR, segmental SNR (SegSNR), perceptual evaluation of speech quality (PESQ) score), and spectrograms with informal listening tests, we show that the proposed speech enhancement method outperforms than the spectral subtractive-type algorithms and improves quality and intelligibility of the enhanced speech.     

On the Microstructure and Wear Behavior of Fe–xCr–4Mn–3C Hardfacing Alloys

The present paper describes an investigation aimed at evaluating the microstructural and dry sliding adhesive wear characteristics of Fe–xCr–4Mn–3C hardfacing alloys applied through shielded metal arc welding. The effect of chromium addition on the microstructure of hardfacings was carried out by using optical microscope, field emission scanning electron microscope and X-ray mapping. Dry sliding wear tests were performed on a pin-on-disc wear tribometer. From the experimental results, it was observed that the primary carbides were refined and increased with the increase of chromium content. The morphology of carbides revealed that the primary carbides were rod shaped. The increased chromium content was also found to be beneficial to enhance hardness and wear resistance of hardfacings. The correlation between hardness and wear resistance exhibited the reliability of hardness as an indicator of the wear performance of hardfacings.     

Challenges and Developments in Secure Routing Protocols for Healthcare in WBAN: A Comparative Analysis

Wireless Personal Communications - The rise in life expectancy of humans, COVID-19 pandemic and growing cost of medical services has brought up huge challenges for the government and healthcare...