Numerical Modelling of Liquid Ramjet Combustors

The liquid fuel ramjet system employing a subsonic side-dump combustor is simulated inthe present study, and the predictions are compared with the available experimental data. Thecomplex combustion phenomenon in a ramjet combustor has been carried out using probabilitydensity function (PDF)  approach. The complexity arises because of the mixing of fuel and airstreams, and the burning of the resultant mixture, within the confined space of the combustionchamber. The predicted numerical results have been validated with the results available in openliterature for a two-dimensional case and with in-house experimental data for a three-dimensionalcase. The methodology allows different designs to be evaluated quantitatively based on theperformance metrics such as combustion efficiency, flame stability, etc.Defence Science Journal, 2008, 58(1), pp.3-14, DOI:http://dx.doi.org/10.14429/dsj.58.162

Numerical Analysis of Integrated Liquid Ramjet Engine

The numerical simulation of an integrated, liquid-fuelled ramjet engine comprising supersonicair intake, subsonic combustor and a convergent-divergent nozzle has been carried out and theresults are discussed in this paper. These results include cold flow studies, heat addition in thecombustor and full engine analysis with coupled simulation of supersonic air-intake andcombustion chamber along with the nozzle. Overall ramjet operation depends on the performanceof the air intake and the combustion chamber.  The coupling phenomena are very dominant andperformance of air intake is affected vastly by the combustor operation and vice versa. In thispaper, a numerical analysis of integrated liquid ramjet engine considering coupling phenomenabetween various sub-systems viz., air intake, combustor and nozzle has been reported

Design and Analysis of Fusion Algorithm for Multi-Frame Super-Resolution Image Reconstruction using Framelet

A enhanced fusion algorithm for generating a super resolution image from a sequence of low-resolution images captured from identical scene apparently a video, based on framelet have been designed and analyzed. In this paper an improved analytical method of image registration is used which integrates nearest neighbor method and gradient method. Comparing to Discrete Wavelet Transform (DWT) the Framelet Transform (FrT) have tight frame filter bank that offers symmetry and permits shift in invariance. Therefore using framelet this paper also present a framelet based enhanced fusion for choosing the fused framelet co-efficient that provides detailed edges and good spatial information with adequate de-noising. The proposed algorithm also has high advantage and computationally fast which are most needed for satellite imaging, medical imaging diagnosis, military surveillance, remote sensing etc.Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 292-299, DOI: http://dx.doi.org/10.14429/dsj.65.826

Mixed Ion and Electron Conducting Ceramics for Gas Sensors

A conventional solid-state synthetic route was used to prepare a mixed conducting double perovskite-type Ba2Ca0.66Nb0.68Fe0.66O6-δ (BCNF66). FTIR study was performed to confirm the chemical stability under 1% CO2, whereas the cross-sectional SEM image was employed to investigate the morphology of the sensor. A comparative study on BCNF66 with and without CO2 in dry synthetic air along with O2 effect was carried out. The significant effect of O2 was observed when CO2 was passed through the sensor in N2. The O2 in dry synthetic air was found to stabilize the CO2 sensor response (current). Furthermore, the addition of ppm level of CO2 in dry synthetic air increased the response

La valoración de empresas en escenarios de incertidumbre

Valorar es emitir una opinión sobre el futuro lo cual es necesariamente subjetivo, independiente de su fundamentación. El elemento subjetivo de la valoración está relacionado con las respuestas a las siguientes inquietudes: valor para qué, valor para quién y valor en qué circunstancias. La valoración tiene un sesgo resultante de los supuestos y los juicios de quien la elabora. No existe un valor absoluto y único para medir una realidad económica, sino un valor razonable por el criterio, la técnica y los supuestos en que se fundamenta. El hecho de usar modelos matemáticos no asegura tal precisión, puesto que los datos que se utilizan tienen incertidumbre y tienen el sesgo de los juicios del avaluador sobre el futuro de la compañía. No podemos esperar tener certidumbre en la valoración cuando los flujos de caja y las tasas de descuento son estimaciones sujetas a error. No existe un valor absoluto y único para medir una realidad económica

Morphological and Electrochemical Properties of Crystalline Praseodymium Oxide Nanorods

Highly crystalline Pr6O11 nanorods were prepared by a simple precipitation method of triethylamine complex at 500°C. Synthesized Pr6O11 nanorods were uniformly grown with the diameter of 12–15 nm and the length of 100–150 nm without any impurities of unstable PrO2 phase. The Pr6O11 nanorod electrodes attained a high electrical conductivity of 0.954 Scm−1 with low activation energy of 0.594 eV at 850°C. The electrochemical impedance study showed that the resistance of electrode was significantly decreased at high temperature, which resulted from its high conductivity and low activation energy. The reduced impedance and high electrical conductivity of Pr6O11 nanorod electrodes are attributed to the reduction of grain boundaries and high space charge width

Li1.5La1.5MO6 (M = W6+, Te6+) as a new series of lithium-rich double perovskites for all-solid-state lithium-ion batteries

Solid-state batteries are a proposed route to safely achieving high energy densities, yet this architecture faces challenges arising from interfacial issues between the electrode and solid electrolyte. Here we develop a novel family of double perovskites, Li1.5La1.5MO6 (M = W6+, Te6+), where an uncommon lithium-ion distribution enables macroscopic ion diffusion and tailored design of the composition allows us to switch functionality to either a negative electrode or a solid electrolyte. Introduction of tungsten allows reversible lithium-ion intercalation below 1 V, enabling application as an anode (initial specific capacity >200 mAh g-1 with remarkably low volume change of ∼0.2%). By contrast, substitution of tungsten with tellurium induces redox stability, directing the functionality of the perovskite towards a solid-state electrolyte with electrochemical stability up to 5 V and a low activation energy barrier (<0.2 eV) for microscopic lithium-ion diffusion. Characterisation across multiple length- and time-scales allows interrogation of the structure-property relationships in these materials and preliminary examination of a solid-state cell employing both compositions suggests lattice-matching avenues show promise for all-solid-state batteries

Structural, electrical conductivity and dielectric relaxation behavior of LiHf2(PO4)3 ceramic powders

Lithium hafnium phosphate LiHf2(PO4)3 (LHP) was synthesized via solid-state synthesis technique. The sintering behavior, structure, and phase composition of the as-prepared sample was analyzed using X-ray diffraction (XRD) characterization technique. The XRD-Rietveld refinement analysis showed that after sintering at low temperatures 500 to 1000 °C, it exhibited various secondary phases. However, a single phase was observed as the sintering temperature increases from 1100 to 1200 °C. LHP sintered at 1100 °C produced real features of sodium superionic conductor type (NASICON-type) with hexagonal crystal axis indicating R-3c space group. The electrical properties were studied using impedance spectroscopy technique. Frequency and temperature dependence behavior of conductivity (ac and dc) and dielectric permittivity were studied. The results obtained describes the conduction mechanism in the system. Electric modulus formalism was performed to investigate the relaxation behavior which showed that as measuring temperature increases, the relaxation frequency increases whereas relaxation time decreases. This behavior explains the hopping mechanism of the charge carriers in the system. Likewise, the correlated barrier hopping model elucidates the dominant hopping mechanism