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Rate Characteristics (rate + characteristic)
Selected AbstractsA model of corrosion fatigue crack growth in ship and offshore steelsFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 8 2007M. JAKUBOWSKI ABSTRACT A model describing corrosion fatigue crack growth rate da/dN has been proposed. The crack growth rate is assumed to be proportional to current flowing through the electrolyte within the crack during a loading cycle. The Shoji formula for the crack tip strain rate has been assumed in the model. The obtained formula for the corrosion fatigue crack growth rate is formally similar to the author's empirical formulae established previously. The different effects of ,K and the fatigue loading frequency f on da/dN, in region I as compared to region II of the corrosion fatigue crack growth rate characteristics can be described by a change of one parameter only: the crack tip repassivation rate exponent. [source] Rheological behaviour of weaning food formulations as affected by addition of maltINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 10 2006Mamudu Halidu Badau Summary Eight weaning food formulations were prepared from the mixture of pearl millet, cowpea and groundnut in the ratio of 70:20:10. The viscosities of gruels from the eight weaning food formulations were determined at eight shear rates and five temperatures, and data obtained were subjected to power-law and Arrhenius equations. The viscosity of the weaning food gruels decreased with increase in shear rate and temperature. The gruels from the eight weaning food formulations exhibited pseudoplastic behaviour. The power-law indices (,n' values) were significantly (P < 0.05) affected by the formulations and changes in temperature. Weaning food formulations that had no malt showed the least sensitivity to temperature, while the one that had 5% ICMV-IS 94206 malt showed the highest. The correlation coefficient ranged from ,0.9993 to ,0.9524, showing that the power-law model adequately described the viscosity and shear rate characteristics of the weaning food gruels. [source] Experimental and CFD studies of fluid dynamic gauging in annular flowsAICHE JOURNAL, Issue 8 2009T. Gu Abstract Fluid dynamic gauging has been applied for the first time to measurements on a curved surface, specifically the inner convex surface of an annulus. Two hydraulic cases were examined: (i) the quasi-static case, where there is no flow in the annulus, other than the flow imposed by the working action of the gauge and (ii) the turbulent case, where there is additionally a forced advective flow in the turbulent regime (14,000 < Reannulus < 32,000). The nozzle clearance,flow rate characteristics resembled those reported previously for flat geometries, with one exception; at small clearance values (0 < h/dt < 0.1), flow rate was found to be independent of clearance because of a leakage flow arising from the curvature of the surface. The experimental results for the quasi-static case showed very good agreement with simulations of the configuration using computational fluid dynamics (CFD). The agreement indicates that the technique may be used not only for measuring the thickness of deposits on curved surfaces, but also for measuring their strength. CFD simulation of the turbulent case was not attempted, but the experimental results imply that the technique could be used reliably as a real-time in situ thickness sensor for this scenario, which is often employed in laboratory fouling studies. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Effect of Voids inside AP Particles on Burning Rate of AP/HTPB Composite PropellantPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 4 2008Makoto KohgaArticle first published online: 21 JUL 200 Abstract Bubble contamination in an ammonium perchlorate (AP)-based composite propellant has a positive effect on the burning rate. However, the quantitative effect of the bubble contamination on the burning rate has never been revealed. In order to clarify the relationship between the increase in the burning rate and the void fraction of the propellant, propellants were prepared with fine porous AP particles (PoAP) or fine hollow AP particles (HoAPs), and their burning rate characteristics were investigated. The voids inside AP particles have the effect of increasing the burning rate. The increase in the burning rate is enhanced linearly as the void fraction increases. The effect of the void fraction on the burning rate for a propellant containing PoAP is not identical with that for a propellant containing HoAP. It was found that the effect of the void fraction on the burning rate could be estimated by the void fraction when the bubble contamination is uniform in size and shape. [source] Thermal Decomposition of NTO: An Explanation of the High Activation EnergyPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 4 2007Valery Abstract Burning rate characteristics of the low-sensitivity explosive 5-nitro-1,2,4-triazol-3-one (NTO) have been investigated in the pressure interval of 0.1,40,MPa. The temperature distribution in the combustion wave of NTO has been measured at pressures of 0.4,2.1,MPa. Based on burning rate and thermocouple measurements, rate constants of NTO decomposition in the molten layer at 370,425,°C have been derived from a condensed-phase combustion model (k=8.08,1013,exp(,19420/T) s,1. NTO vapor pressure above the liquid (ln P=,9914.4/T+14.82) and solid phases (ln P=,12984.4/T+20.48) has been calculated. Decomposition rates of NTO at low temperatures have been defined more exactly and it has been shown that in the interval of 180,230,°C the decomposition of solid NTO is described by the following expression: k=2.9,1012,exp(,20680/T). Taking into account the vapor pressure data obtained, the decomposition of NTO in the gas phase at 240,250,°C has been studied. Decomposition rate constants in the gaseous phase have been found to be comparable with rate constants in the solid state. Therefore, a partial decomposition in the gas cannot substantially increase the total rate. High values of the activation energy for solid-state decomposition of NTO are not likely to be connected with a sub-melting effect, because decomposition occurs at temperatures well below the melting point. It has been suggested that the abnormally high activation energy in the interval of 230,270,°C is a consequence of peculiarities of the NTO transitional process rather than strong bonds in the molecule. In this area, the NTO molecule undergoes isomerization into the aci -form, followed by C3-N2 heterocyclic bond rupture. Both processes depend on temperature, resulting in an abnormally high value of the observed activation energy. 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