Rheological studies on energetic thermoplastic elastomers

Energetic thermoplastic elastomers containing energetic groups, such as azido, nitrato, nitro, and so forth, are emerging as attractive binder systems for advanced solid rocket propellants. Poly[3,3‐bis(Azidomethyl) oxetane (BAMO)‐co‐3‐azidomethyl‐3‐methyl oxetane (AMMO)] comprising hard crystalline BAMO segment and the soft/amorphous AMMO segment in various molar ratios (80 : 20, 50 : 50 and 20 : 80) were synthesized during the present work. The homo polymers namely Poly‐BAMO and Poly‐AMMO were also synthesized. All the polymers and copolymers were characterized by spectral and thermal methods. They were found to be thermally stable. The most promising 80 : 20 copolymer softened at 56°C with T_g of −36°C. Rheological studies were also carried out to determine their suitability as a binder in explosive and propellant formulations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Strain mediated enhancement in magnetoelectric properties of sonochemically synthesized piezoelectric and piezomagnetic composites

Materials with magneto-electric (ME) properties are of great importance because of their demand in electronic industries. Three dimensional nano-particles of the ME-composites having the general formula (1-x)CoCr_0.3Fe_1.7O₄(CCFO)+(x)BaTiO₃(BTO) (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were obtained by comprising the piezoelectric-BTO and piezomagnetic-CCFO phases. The individual phases of CCFO and BTO were synthesized separately by ultrasonic irradiation assisted sonochemical and sol-gel routs. X-ray diffraction patterns (XRD) confirmed the well-crystalline nature of both the phases. BTO and CCFO phases were under tensile strain as confirmed by the variation in lattice constants with varying proportion of BTO and CCFO. An energy-dispersive X-ray spectroscopy spectrum confirmed the phase purity of the samples and stoichiometric concentration of elements. Magnetic properties were investigated by M ? H loop measurements and dielectric properties by using RF impedance analyzer. Dielectric constant increased with the increasing percentage of BTO. The maximum value of ME coefficient (24.7 mV/cm?Oe) is observed for the 60%CCFO+40%BTO sample. The obtained results were discussed in the light of grain size, strain and the basic properties of the individual phases. The prepared materials can be applicable in electronic devices where high magneto-electric coefficient is desirable.     

Studies on Advanced RDX/TATB Based Low Vulnerable Sheet Explosives with HTPB Binder

Hydroxyl‐terminated polybutadiene (HTPB) based sheet explosives incorporating insensitive 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) as a part replacement of cyclotrimethylene trinitramine (RDX) have been prepared during this work. The effect of incorporation of TATB on physical, thermal, and sensitivity behavior as well as initiation by small and high caliber shaped charges has been determined. Composition containing 85% dioctyl phthalate (DOP) coated RDX and 15% HTPB binder was taken as control. The incorporation of 10–20% TATB at the cost of RDX led to a remarkable increase in density (1.43→1.49 g cm⁻³) and tensile strength (10→15 kg cm⁻²) compared to the control composition RDX/HTPB(85/15). RDX/TATB/HTPB based compositions were found less vulnerable to shock stimuli. Shock sensitivity was found to be of the order of 20.0–29.2 GPa as against 18.0 GPa for control composition whereas their energetics in terms of velocity of detonation (VOD) were altered marginally. Differential scanning calorimeter (DSC) and thermogravimetry (TG) studies brought out that compositions undergo major decomposition in the temperature region of 170–240 °C.     

Blind quality scalable video compression algorithm for low bit-rate coding

Multimedia Tools and Applications - An efficient way of using Embedded Zero-trees of Wavelet (EZW) architecture for video compression, termed as “Two Threshold EZW”, has been introduced...     

Study of thermally coupled distillation systems for energy-efficient distillation

Distillation is one of the most widely used separation unit operations in process industries, although it is quite energy intensive. In many cases, the enormous energy requirements for distillation make it economically infeasible to carry out the separation. Thermally coupled distillation system (TCDS) is an advanced distillation method that provides significant energy savings of about 30% as compared with conventional distillation column sequences. The most well-known TCDS sequence, the Petlyuk configuration, has some operational challenges due to bidirectional vapour flow, which makes its implementation difficult in two-column mode. To overcome these limitations, a number of unidirectional vapour flow configurations have been proposed in the literature. The work on simulation analysis for such configurations is limited. In this paper, simulation models for two such configurations are developed, analyzed and compared with the Petlyuk and conventional distillation column sequences for separation of equimolar mixture of benzene–toluene–ethylbenzene.     

Bis(azidomethyl) oxetane/hydroxyl‐terminated polybutadiene/bis(azidomethyl) oxetane triblock copolymer: Synthesis and characterization

A copolymer consisting of bis(azidomethyl) oxetane and hydroxyl‐terminated polybutadiene was synthesized with different monomer ratios via an activated monomer mechanism. The copolymer thus obtained was characterized with Fourier transform infrared, ¹H‐NMR, molecular weight, and polydispersity measurements. Rhe‐ological and thermal studies were also carried out. The mechanical properties of the gum stock obtained through curing with toluene diisocyanate and crosslinking with pyrogallol at about 50°C were also determined. This was an attempt to combine the useful properties of hydroxyl‐terminated polybutadiene (a nonenergetic binder providing excellent mechanical properties) and poly[bis(azidomethyl) oxetane] (an energetic binder). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Thermodynamic analysis and experimental validation of multi-composition ammonia liquor absorption engine cycle for power generation

Energy conservation, utilization, and effective integration are of utmost importance for future sustenance. Accordingly, this work focuses on the generation of power from the low-grade temperature below 150°C . A proposed novel multi-composition ammonia liquor absorption engine (MALAE) power cycle can be used toward the above purpose by supplying renewable energy obtained from low concentration type solar collectors. Proposed MALAE power cycle minimizes heal loss due to heat recovery and uses high purity NH₃ vapors to expand through the isentropic turbine. MALAE power system is modeled and simulated using NH₃-H₂O as a working fluid for a reboiler temperature of 115°C . The purpose of this work is to simulate the proposed MALAE power cycle with the distillation column and two solution heat exchanger (SHE). MALAE modeling and simulation is accomplished in SCILAB software. The simulation outcome is validated with the pilot-scale 5 kW experimental setup and validation showed ±5% deviation. A comparison of MALAE cycle with published cycles signifies higher efficiency of MALAE cycle toward the utilization of low-grade energy from a temperature range of 100°C to 150°C . Finally, detailed parametric analysis of MALAE cycle efficiency is presented in terms of number of plates, distillation pressure and vapor flowrate, absorber temperature, pressure partial condenser temperature, and heat loads.     

Study on Mixed Glycols-based Semi-flexible Unsaturated Polyester Resins for Inhibition of Rocket Propellants

Seven semiflexible unsaturated polyester resins based on isophthalic acid, maleic anhydride and polyethylene glycol-200 and propylene glycol (in different proportions) have been synthesised and characterised for gel time, exotherm peak temperature, tensile strength, percentage elongation, bond strength, nitroglycerine absorption, water absorption, flame resistance and voltile losses. The effect of glycol variation on these properties has also been discussed. Based on the data for various characteristics, resin 4 has been selected for inhibition and static evaluation of propellant. The propellant sustainers containing 2 NDPA have been inhibited with resin 4 without the application of any barrier coats and statically fired at ambient, cold and hot temperatures. The results of the static firings prove the worthiness of the new direct bonding inhibition system.     

Global-patch-hybrid template-based arbitrary object tracking with integral channel features

Arbitrary object tracking is a challenging task in computer vision, as many factors affecting the target representation must be considered. A target template based on only the global appearance or on only the local appearance is unable to capture the discriminating information required for the robust performance of a tracker. In this paper, the target appearance is represented using a hybrid of global and local appearances along with a framework to exploit the Integral Channel Features (ICF). The proposed hybrid approach achieves fusion of the conventional global and patch-based approaches for target representation to synergize the advantages of both approaches. The ICF approach under the hybrid approach integrates heterogeneous sources of information of the target and provides feature strength to the hybrid template. The use of ICF also expedites the extraction of the structural and color features from video frames as the features are collected over multiple channels. The target appearance representation is updated based on only samples with appearances similar to the target appearance using clustering and vector quantization. These factors offer the proposed algorithm robustness to occlusion, illumination changes, and in-plane rotation. Further experimentation analyzes the effects of a change in the scale of the bounding box on the tracking performance of the proposed algorithm. The proposed approach outperforms all the state-of-the-art algorithms in all considered scenarios.     

Statistical optimization of process parameters for the production of vanillic acid by solid‐state fermentation of groundnut shell waste using response surface methodology

BACKGROUND: Vanillic acid is a flavoring agent and also serves as precursor for vanillin production. Culture medium and fermentation condition for the single step production of vanillic acid from Phanerochaete chrysosporium using lignocellulosic waste as a substrate under solid state fermentation (SSF) were optimized using response surface methodology. RESULTS: The process parameters were chosen by borrowing methodology, and L‐asparagine, pH and moisture content of the solid medium during SSF were identified as the most significant variables. The optimum value of selected variable and their mutual interactions were determined by response surface methodology. The result demonstrated that a yield of 73.58 mg vanillic acid g^?1 substate was predicted under optimum conditions (L‐asparagine 5.98 mmol L^?1 (2.37 mg g^?1 groundnut shell), pH of solid medium 4.51 and moisture content 74.83%). The predicted response was experimentally validated and resulted in a maximum vanillic acid yield of 73.69 mg g^?1 after 8 days of SSF. CONCLUSION: The optimization of fermentation variables resulted in a maximum 10‐fold increase in vanillic acid yield compared with that observed under sub‐optimal conditions (from 7.2 mg g^?1 to 73.69 mg g^?1). Copyright © 2011 Society of Chemical Industry