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  • Author or Editor: L. Elegant x
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Abstract  

A program is described which enables performing of genetic algorithms for the determination of two positive real parameters. These new types of procedures are tested on a software of determination of flame temperatures previously developed in a fully classic way. The genetic operators used are crossover and mutation. They perform operations on a binary coded form of the parameters. The goal of the present study consists in developing and optimizing a genetic determination of the parameters at a given temperature. We succeed in selecting the general architecture of the procedure and implementing it in our main software of calculation of flame temperature. We have chosen this pyrotechnic field of application because we knew the behaviour of the real parameters, so the debugging operations were easier.

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Abstract  

Some DSC calorimeters such as the model Setaram DSC 111 allow the user to set the parameters of temperature programming. Default values furnished by the constructor are often used, but it is very interesting to study the thermal behaviour of the regulation of the calorimeter under different conditions and kinds of set point temperatures. For this research we have developed in C a set of softwares in order to show the behaviour of the proportional integral derivative (PID) controller of the DSC. It can help the user to choose correct values for P, I and D parameters according to the kind of experiment conducted. The software allows studies for extra parameters such as the sampling rate of the computerized PID controller or the determination of filtering of the correction.

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Abstract  

Some DSC calorimeters, such as the model DSC 111, built by the society Setaram, allow the user to set the temperature programming parameters. Usually default values furnished by the constructor are often used, but it is very interesting to study the thermal behaviour of the regulation of the calorimeter under different conditions and with different kinds of set point temperatures. For this research, we have developed in C language a set of software in order to demonstrate the behaviour of the (proportional integral derivative) PID controller of the DSC. It can help the user to choose correct values for P, I and D parameters according to the kind of experiment conducted. The software allows studies of extra parameters, such as the sampling rate of the computerized PID controller or the determination of filtering of the correction.

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Abstract

Feedforward neural networks have been used for kinetic parameters determination and signal filtering in differential scanning calorimetry. The proper learning function was chosen and the network topology was optimized, using an empiric procedure. The learning process was achieved using simulated thermoanalytical curves. The resilient-propagation algorithm have led to the best minimization of the error computed over all the patterns. Relative errors on the thermodynamic and kinetic parameters were evaluated and compared to those obtained with the usual thermal analysis methods (single scan methods). The errors are much lower, especially in presence of noisy signals. Then, our program was adapted to simulate thermal effects with known thermodynamic and kinetic parameters, generated electrically, using a PC computer and an electronic interface on the serial port. These thermal effects have been generated by using an inconel thread.

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Equilibrium constants and enthalpy changes are reported between a series of substituted methylpyridines and the chelate tris(dipivaloylmethanato)europium(III) in chloroform solution at 36° as obtained by calorimetric measurements. The 1∶1 adduct enthalpies are ordered in agreement with the electronic and steric effects of the methyl group in a to the heteroatom. Some anomalies are observed when the concentration ratio between ligand and chelate is higher than unity. These findings conform with the hypothesis of the existence of a supplementary equilibrium which may be assigned to the formation of the 1∶2 adduct.

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Abstract  

A program is described which enables data processing of theoretical temperatures of flames of pyrotechnic reactions. This software has been developed with simplified mathematics. A very large database of thermodynamic characteristics allows a very important number of different calculations of temperatures. The program takes into account the phenomena of dissociation of the most important species present in the reactions that we have to use. The results that we obtained with this computer program are very satisfying.

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Abstract  

In the case of a complex mechanism of two parallel independent reactions, peak maximum evolution methods and model-fitting methods give only a mean value of the kinetic parameters, while isoconversional methods are useful to describe the complexity of the mechanism. Isothermal and non-isothermal isoconversional methods can be used to elucidate the kinetics of the process. Nevertheless, isothermal isoconversional methods can be limited by restrictions on the temperature regions experimentally available because of duration times or detection limits.

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Absorption heats of hydrogen sulphide in aqueous solutions of monoethanolamine, diethanolamine and triethanolamine were determined by calorimetry. The measured enthalpies were compared to those calculated on the basis of solubility measurement and to the enthalpies of protonation of hydrogen chloride at 25‡.

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