Electromechanical analytical model of shape memory alloy based tunable cantilevered piezoelectric energy harvester

International Journal of Mechanics and Materials in Design - The resonant frequency of electromechanical energy harvester should be tuned to ambient frequency so as to maximize the harvester power....     

Characterization and Low Temperature Study of Iron Telluride Thin Films Upon Ageing and Oxygen Ion Irradiation

The occurrence of superconductivity in iron telluride thin films has been observed upon ageing. The superconducting transition is found to be very robust under an application of magnetic fields up to 10 T. Infrared and Raman spectroscopic characterization of the aged films reveal the formation of Fe_1+δTeO _x upon ageing. As an alternative method of introducing oxygen in FeTe thin film, oxygen ion irradiation has also been carried out It is found that the irradiated film becomes increasingly disordered and ultimately transforms to an amorphous phase upon increasing the irradiation dose. Investigation of electrical resistivity and optical reflectivity of the irradiated FeTe films indicates an interesting possibility of an ion irradiationinduced phase change memory material in analogy to the phase change characteristics of laserirradiated FeTe films.     

A study on the redistribution of ion-implanted nitrogen in Ti-modified austenitic steel

Titanium modified austenitic steel has been subjected to nitrogen implantation to different fluences. There is a considerable deviation of the experimental depth profile of nitrogen from the theoretical profile obtained using Monte-Carlo codes. Available literature ascribes such redistribution to sputtering; by following the implanted nitrogen and the vacancy-defects alongside using resonance nuclear reaction analysis and positron annihilation spectroscopy, clear experimental evidence for the formation of vacancy-nitrogen complexes is established. The possibility of role of complexes in redistributing the implanted nitrogen is explored here for the first time.     

Sleepy keeper style based Low Power VLSI Architecture of a Viterbi Decoder applying for the Wireless LAN Operation sustainability

Analog Integrated Circuits and Signal Processing - Remarkable progress in the field of wireless communication has created a research interest for Viterbi decoder with long duration of battery life,...     

Incorporation of oxygen during oxidative annealing of thermally evaporated In films

The paper describes studies on compositional, morphological and optical characteristics of thin indium oxide films prepared by annealing thermally evaporated indium metal films in 423-723 K temperature range in air. The incorporation of oxygen in the films has been probed by depth profiling oxygen using ¹⁸O(p, α)¹⁵N nuclear reaction and 3.05 MeV ¹⁶O(α, α)¹⁶O resonant scattering. The morphology of the films has been examined by atomic force microscopy while their structure by glancing incidence X-ray diffraction. As grown In films are polycrystalline and consist of well-aligned (In) hillocks. The hillocks in thin films (∼12 nm) are nanosized and conical in shape while those in thicker films (∼130 nm) are micron-sized with rather flat tops. Nanosized hillocks impart films enhanced reactivity towards oxygen. Consequently thinner films contain high amount of adsorbed oxygen in as-deposited state and undergo facile oxidation. The hillocks are obliterated in the process. The enhanced reactivity is attributed to high surface energy, generally associated with nanoparticles, and residual stress. These films exhibit high transmission (>90%) on annealing beyond 473 K. Micro-sized hillocks, on the other hand lend pronounced roughness to the films. Roughness and lower surface free energy which manifests in the form of flatter hillock tops, make the films oxidation-resistant. Depth profile measurements in thicker films show that oxidation starts at the surface and proceeds into the interiors of the film with increase in the duration of annealing. The films are deficient in oxygen, even as X-ray diffraction shows the formation of polycrystalline indium oxide. These have low transmission (<30%) and their band gaps increase with the temperature and duration of annealing. The increase in band gap is attributed to the gradual oxidation of interior regions that are initially significantly deficient in oxygen and improvement in crystallinity.     

Automatic segmentation of cerebral hemispheres in MR human head scans

Automatic segmentation of cerebral hemispheres in magnetic resonance (MR) brain images help to quantify the brain asymmetry and correct several MR brain deformities. The detection of mid‐sagittal plane (MSP) in human brain image is necessary to segment the hemispheres for both operator‐based and automated brain image asymmetric analysis. In this article, a computationally simple and accurate technique to detect MSP in MRI human head scans using curve fitting is developed. The left and right hemispheres are segmented based on the detected MSP. The accuracy of the MSP is evaluated by comparing the segmented left and right hemispheres against the manually segmented ones. Experimental results using 78 volumes of T1, T2 and PD‐weighted MRI brain images show that the proposed method has accurately segmented the cerebral hemispheres based on the detected MSP in axial and coronal orientations of normal and pathological brain images.     

Optimal Reconfiguration in Radial Distribution System Using Gravitational Search Algorithm

This article presents an innovative technique for solving network reconfiguration problems with an objective of minimizing network I²R losses for an explicit set of loads. Amid many performance standards considered for optimal network reconfiguration, voltage constraint is an important one. This problem calls for determining the best combination of feeders to be opened in the radial distribution system so it provides optimal performance in the preferred settings. In solving this problem, the gravitational search algorithm is used to reconfigure the radial distribution system; this algorithm practices an optimal pattern for sustaining the radial nature of the network at every stage of the solution, and it further allows proficient exploration of the solution space. The anticipated scheme minimizes the objective function, which has been given in the problem formulation to reduce I²R losses in addition to balancing loads in the feeders. The solution technique involves determination of the best switching combinations and calculation of power loss and voltage profile. The practicality of the anticipated technique is validated in two distribution networks, where attained results are compared by means of available literature. Correspondingly, it is seen from the results that network losses are reduced when voltage stability is enriched through network reconfiguration.     

Synthesis and characterization of SnS nanosheets through simple chemical route

Tin Sulfide (SnS) nanosheets were synthesized by wet chemical route using ethylene glycol (EG) and without using any surfactant. Structural and phase purity were confirmed by powder X-ray diffraction pattern which shows the orthorhombic structure of SnS. The sheets like morphology and particle size of the synthesized product were identified by using analytical transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM). Agglomeration of SnS nanoparticles was found to lead to the formation of nanosheets. UV-VIS-NIR absorption spectrum of SnS nanosheets shows the direct transition at 1.88 eV. Compared to bulk band gap a blue shift of 0.58 eV has been observed for direct transition. This is due to the quantum confinement effect. Room temperature photoluminescence spectrum of SnS nanosheets shows two emission bands at 1.75 and 1.57 eV respectively which are assigned to band gap and defect level transitions.     

A distributed parametric model of Brinson shape memory alloy based resonant frequency tunable cantilevered PZT energy harvester

International Journal of Mechanics and Materials in Design - This paper presents, an analytical model of piezoelectric vibration energy harvester consists of Brinson shape memory alloy (SMA) plate...     

Synthesis and vibrational properties of aluminum-scandium tungstate solid-solution

Homogeneous solid solutions Al_{2 − x} Sc _x (WO₄)₃belonging to the orthorhombic structure were synthesized from stoichiometric mixtures of Al₂O₃, Sc₂O₃, and WO₃using solid-state reaction method. The powder X-ray diffraction patterns confirmed the formation of single phase solid-solution and a monotonic variation of the cell parameters over the complete range of composition x. The vibrational properties of the mixed crystals were investigated using Raman spectroscopy. The Raman spectra consisted of lattice modes and internal modes of the tungstate tetrahedra. The end members exhibited large number of sharp Raman peaks while the mixed crystals of intermediate composition contained lesser number of broad peaks suggesting a positional disorder. Most of the prominent modes were found to exhibit the one-mode behaviour.