Technical review: Improvement of mechanical properties and suitability towards armor applications – Alumina composites

Ceramic Matrix Composites (CMCs) have many interesting properties, mainly light weight, cost efficiency, low density, high compressive strength, high hardness and durability. Hence, they emerged as a boon to the development of personnel armors in the past. The current work aims to review various new methodologies adapted for the reinforcement of Alumina (Al₂O₃) CMCs in recent times, including some of the interesting results obtained with respect to mechanical properties, suitability of the synthesized composites for armor applications, and the upcoming reinforcement trends. Finally, studies related to reinforcement in Al₂O₃ CMCs, specifically towards armor applications have been consolidated to arrive at some of the important inferences for concluding reasonably.     

Crystallization and characterization of Na2(La,Me)Zr(PO4)3

Na₂(La, Me)Zr[PO₄]₃ (where Me=Co, Al, Cr) crystals have been grown by three methods: by chemical reaction; from highly concentrated phosphoric acid solutions; and by a hydrothermal technique. The advantages and disadvantages of each method to obtain these crystals have been discussed. Morphological, X-ray, chemical analysis and IR-spectral studies were performed on these crystals.     

Design of a Compressive Sensing Based Fall detection System for Elderly Using WSN

Wireless Personal Communications - Recent researches have pointed out that one third persons are aged 65 and above requires special health care. As the number of elderly person is increasing, home...     

Optical Diagnostics Study of Gas Particle Transport Phenomena in Cold Gas Dynamic Spraying and Comparison with Model Predictions

Cold gas dynamic spraying (CGDS), a relatively new thermal spraying technique has drawn a lot of attention due to its inherent capability to deposit a wide range of materials at relatively low-operating temperatures. A De Laval nozzle, used to accelerate the powder particles, is the key component of the coating equipment. Knowledge concerning the nozzle design and effect of process parameters is essential to understand the coating process and to enable selection of appropriate parameters for enhanced coating properties. The present work employs a one-dimensional isentropic gas flow model in conjunction with a particle acceleration model to calculate particle velocities. A laser illumination-based optical diagnostic system is used for validation studies to determine the particle velocity at the nozzle exit for a wide range of process and feedstock parameters such as stagnation temperature, stagnation pressure, powder feed rate, particle size and density. The relative influence of process and feedstock parameters on particle velocity is presented in this work.     

Electrochemical and thermal behaviour of LiNi0.8Co0.2O2 cathode in sealed 18650 Li-ion cells

The electrochemical performance of LiNi_0.8Co_0.2O₂ cathodes in Li ion cells was investigated under static and dynamic load conditions, which prevail in electric and hybrid vehicles using constant current constant voltage and hybrid pulse power characteristic procedures.The thermal properties of this cathode were investigated using the differential scanning calorimetric and accelerated rate calorimetric techniques. The cell fabricated with a LiNi_0.8Co_0.2O₂ cathode showed excellent power performance. The specific energy produced by the 18650 cell was 90 Wh kg^–1 at 100 W kg^–1 power level.     

Experimental investigation on low concentration nanofluids with Fresnel lens and evacuated tubes for solar applications

Optical and thermo-physical properties of the nanofluids play a major role in the absorption of solar energy. In the present study, photo-thermal energy conversion of low concentration Al₂O₃/Deionised water (DI) water and CuO/DI water nanofluids in solar thermal collector is experimentally investigated. Properties of 50,100,150, and 200 ppm concentrations of nanofluids are reported. The absorbance results in the visible range indicate that CuO nanofluid of 200 ppm concentration is nearly three times higher compared to Al₂O₃ nanofluid. The extinction coefficient, optical energy band gap, and photoluminescence obtained from the absorbance data are also reported. Surfactant free nanofluids are used, and the thermal conductivity measurements show a negligible enhancement for both the nanofluids. Maximum receiver temperatures of 89 and 72°C are found with CuO and Al₂O₃ nanofluids, respectively, for the maximum concentration. A maximum receiver efficiency of 34.89% is obtained for CuO nanofluids.     

COMBINED OSMOTIC AND MICROWAVE DRYING OF STRAWBERRIES

Strawberries pretreated with 2% ethyl oleate and 0.5% NaOH were osmotically dehydrated and their osmotic dehydration rate is compared with untreated berries. It was found that treated berries dehydrated belter compared to untreated berries. Osmotically dehydrated berries were convective and microwave dried at different power levels and results were compared with respect to drying time and rate. The rehydration ratio, texture, color and sensory values are compared with freeze dried strawberries with the same pretreatment. It was found that microwave drying was short in time and the quality parameters of the microwave dried berries were comparable to those of freeze dried berries.     

Effects of lignocaine on intramyocardial conduction in nonischaemic and ischaemic canine myocardium

The effect of lignocaine (USP: lidocaine) on intramyocardial conduction in ischaemic and nonischaemic areas of the left ventricular myocardium was determined in 11 mongrel dogs. Intramyocardial conduction times were assessed during control conditions, 15 min after coronary ligation, and following lignocaine administration. Coronary occlusion resulted in a disparity between the conduction velocities in the ischaemic and nonischaemic zones. Ater lignocaine administration conduction to the ischaemic area was further decreased. However, conduction to the nonischaemic area was decreased to a relatively greater extent, resulting in a significant decrease in the disparity of conduction velocities in the two areas. It is concluded (1) that lignocaine exerts dissimilar quantitative effects on the nonischaemic and acutely ischaemic myocardium and (2) that these differential effects decrease the inhomogeneity of intraventricular conduction. It is possible that this action may play a role in the suppression of re-entrant arrhythmias.