An Improved Ce/Se Scheme And Its Application To Detonation Propagation

An improved two-dimensional space-time conservation element and solution element ( CE/ SE) method with second-order accuracy is proposed, examined and extended to simulate the detonation propagations using detailed chemical reaction models. The numerical results of planar and cellular detonation are compared with corresponding results by the Chapman-Jouguet theory and experiments, and prove that the method is a new reliable way for numerical simulations of detonation propagation.

Preparation And Optical Properties Of Cdte/Cdo Center Dot Nh(2)O Core/Shell Nano-Composites In Aqueous Solution

The deposition of CdO center dot nH(2)O On CdTe nanoparticles was studied in an aqueous phase. The CdTe nanocrystals (NCs) were prepared in aqueous solution through the reaction between Cd2+ and NaHTe in the presence of thioglycolic acid as a stabilizer. The molar ratio of the Cd2+ to Te2- in the precursory solution played an important role in the photoluminescence of the ultimate CdTe NCs. The strongest photoluminescence was obtained under 4.0 of [Cd2+]/[Te2-] at pH similar to 8.2. With the optimum dosage of Cd(II) hydrous oxide deposited on the CdTe NCs, the photoluminescence was enhanced greatly. The photoluminescence of these nanocomposites was kept constant in the pH range of 8.0-10.0, but dramatically decreased with an obvious blue-shifted peak while the pH was below 8.0. In addition, the photochemical oxidation of CdTe NCs with cadmium hydrous oxide deposition was markedly inhibited.

Electrochemical Impedance Spectroscopy Of Peo Coating On Aluminum Alloy In Nacl Solution

Various Plasma Electrolytic Oxidation (PEO) ceramic coatings were prepared on LY12 aluminum alloy by adjusting the concentration of sodium silicate solution. Optical microscope (OM), XRD and EIS were used to study their morphology, composition and anti corrosion behavior in NaCl solution. Increasing concentration of sodium silicate leads to the increase of the total coating thickness while too high and too low concentration lead to the decrease of inner dense layer. The main composition of PEO coatings prepared in 20, 40 and above 60g/L concentration solution are correspondingly alumina, alumina with mullite, and amorphous phase. The corrosion resistance is determined by the inner dense layer. Increasing the thickness of inner dense layer can improve the anti-corrosion performance. PEO coating's corrosion resistance in acidic, alkaline and neutral NaCl solution is proved and the corrosion mechanism involved is also discussed.

Extended Stoney'S Formula For A Film-Substrate Bilayer With The Effect Of Interfacial Slip

The curvature-stress relation is studied for a film-substrate bilayer with the effect of interfacial slip and compared with that of an ideal interface without interfacial slip. The interfacial slip together with the dimensions, elastic and interfacial properties of the film and substrate layers can cause a significant deviation of curvature-stress relation from that with an ideal interface. The interfacial slip also results in the so-called free edge effect that the stress, constraint force, and curvature vary dramatically around the free edges. The constant curvature as predicted by Stoney's formula and the Timoshenko model of an ideal interface is no longer valid for a bilayer with a nonideal interface. The models with the assumption of an ideal interface can also lead to an erroneous evaluation on the true stress state inside a bilayer with a nonideal interface. The extended Stoney's formula incorporating the effects of both the layer dimensions and interfacial slip is presented.

Distributed maximum likelihood for self-localization in sensor networks

We show that the sensor localization problem can be cast as a static parameter estimation problem for Hidden Markov Models and we develop fully decentralized versions of the Recursive Maximum Likelihood and the Expectation-Maximization algorithms to localize the network. For linear Gaussian models, our algorithms can be implemented exactly using a distributed version of the Kalman filter and a message passing algorithm to propagate the derivatives of the likelihood. In the non-linear case, a solution based on local linearization in the spirit of the Extended Kalman Filter is proposed. In numerical examples we show that the developed algorithms are able to learn the localization parameters well.

Dynamic mode I perturbation solution for a moving crack unsteadily

Rice et al. (Jounal of Mechanics and Physics of Solids 42, 813-843) analyze the propagation of a planar crack with a nominally straight front in a model elastic solid with a single displacement component. Using the form of Willis er al. (Journal of the Mechanics and Physics of Solids 43, 319-341), of dynamic mode I weight functions for a moving crack, we address that problem solved by Rice ei al. in the 3D context of elastodynamic theory. Oscillatory crack tip motion results from constructive-destructive interference of stress intensity waves. Those waves, including system of the dilatational, shear and Rayleigh waves, interact on each other and with moving edge of crack, can lead to continuing fluctuations of the crack front and propagation velocity. (C) 1997 Elsevier Science Ltd.