Forming process stage experimental-simulation

Most of the kinetics equations established at the early stage of the studies were based on elementary functions. Therefore, the form of these equations varied from one study to another. Because the establishment of these equations was not based on the theoretical model, and most of them were represented by elementary functions, the theoretical and experimental crystallization curves just partially matched each other. Later, some crystallization kinetics equations based on designed theoretical models were established as well. Recently, the crystallization process was further simulated by the computational modeling approach. 

A typical experiment is shown in Fig. 4. Pressure, temperature, vapour mass fraction and saturation ratio are compared with numerical calculation. The characteristic time r, required for numerical evaluation, is obtained by a fit of the experimental vapour mass fraction signal, resulting in r = 5 ms. The chosen values of critical saturation ratio and piston velocity are rather arbitrary. The experimental saturation ratio is calculated from pressure, temperature and vapour mass fraction. When no liquid mass can be detected, the vapour mass fraction is set to the initial value. Experiment and numerical simulation agree fairly well. The first part of the expansion of the gas-vapour mixture is isentropic and accounts for an increase of the saturation ratio. Condensation on the heterogeneous nuclei starts at a value of the measured saturation ratio of about three. After the onset of condensation a rise in temperature is observed due to the release of latent heat. The saturation ratio tends to unity as time increases. The plateau formed in the numerical solution is not observed in the experimental signal. Obviously, the experimental condition is far from self-similarity, and the expansion process is still in its early stage, where relaxation is dominant. The simple numerical model does not describe accurately the... 

Generated on the first stage mononitrene eould rearrange into a cyclic carbodiimide, but observation of only a weak IR band at around 1900 cm indicated that the rearrangement was a minor process in this ease [99], The final trinitrene readily decomposed into three NCN molecules upon further photoirradiation. The triplet NCN was identified by ESR spectrum D/hc = 1.545 cm", E/hc = 0.000 cm, as determined by simulation), IR band at around 1475 cm", and UVA is absorption bands one intense peak at 329 nm accompanied by vibronic bands at 290- 300 nm. Experimental IR fi equeneies, UV-vis absorption bands, and ESR fine-strueture parameters of mono-, di and tri-nitrenes formed from triazidotriazine are collected in Table 18. 

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