Modeling and Optimization of M-cresol Isopropylation for Obtaining N-thymol: Combining a Hybrid Artificial Neural Network with a Genetic Algorithm

The application of a hybrid framework based on the combination, artificial neural network-genetic algorithm (ANN-GA), for n-thymol synthesis modeling and optimization has been developed. The effects of molar ratio propylene/cresol (X1), catalyst mass (X2) and temperature (X3) on n-thymol selectivity Y1 and m-cresol conversion Y2 were studied. A 3-8-2 ANN model was found to be very suitable for reaction modeling. The multiobjective optimization, led to optimal operating conditions (0.55 ≤X1≤0.77; 1.773 g ≤ X2 ≤1.86 g; 289.74 °C ≤ X3 ≤291.33 °C) representing good solutions for obtaining high n-thymol selectivity and high m-cresol conversion. This optimal zone corresponded to n-thymol selectivity and m-cresol conversion ranging respectively in the interval [79.3; 79.5]% and [13.4 %; 23.7]%. These results were better than those obtained with a sequential method based on experimental design for which, optimum conditions led to n-thymol selectivity and m-cresol conversion values respectively equal to 67%and 11%. The hybrid method ANN-GA showed its ability to solve complex problems with a good fitting

Expérimentations numériques sur les variantes et paramètres de la méthode du recuit simulé

La méthode du recuit simulé, largement utilisée en génie des procédés, nécessite le codage des solutions potentielles, et comporte de nombreuses variantes dans sa mise en oeuvre ainsi que plusieurs paramètres de contrôle. Ces divers points sont étudiés sur la base de six fonctions à solutions connues, afin de déterminer des règles générales d’utilisation de la procédure. La méthode stochastique d’acceptation des solutions de Metropolis et al. (1953) combinée avec le schéma de décroissance géométrique de la température de Kirkpatrick et al. (1982) sont les variantes les plus efficaces. Parmi les trois codages test´es, aucun ne supplante les autres. La température initiale, la longueur du palier de température, le facteur multiplicatif de décroissance de la température et le test d’arrêt ont été étudiés au moyen d’un plan factoriel 24. Le paramètre le plus important est la longueur du palier de température, le moins important est la température initiale, et le coefficient de décroissance de la température et le nombre de paliers pour effectuer l’arrêt ont une importance similaire

Calibration of building energy simulation models based on optimization: A case study

This study applies an optimization-based approach for calibrating building energy models using monitored data. The calibration was carried out on a test building coupling the EnergyPlus energy simulation tool with the GenOpt optimization tool. The objective function was set to minimize the difference between simulated and monitored energy consumption. For evaluating the model accuracy, the Mean Bias Error (MBE) and the Coefficient of Variation of the \RMSE\ (Cv (RMSE)) were calculated and found consistent with \ASHRAE\ guideline 14 limits for a model to be considered calibrated

A Wedding Gone Wrong The Rather Worldly Woes of a Rather Wealthy Qādirī Sufi Shaykh. Two 18th Century Documents from the Ottoman Court Records of Ḥamā and Aleppo

A rather intricate legal case took place first in Ḥamā’s and then in Aleppo’s Ottoman Islamic courts around the middle of the 18th century. The setting, the social standing of the individuals involved, and the alleged circumstances of the case all contribute to make clear that this was not just another routine court case. Altogether, the two documents are a good example of the scope and quality of the information preserved in the archives of local courts and they both demonstrate the extent and modes of implementation of Islamic law in a specific Ottoman milieu. The long inventory of personal property in the Aleppo document gives us a good idea of the social status and affluence enjoyed by the plaintiff – a member of the Jīlānī/Qādirī family - and an interesting insight into material culture and what constituted wealth and affluence at the time.

Optmization-based calibration for dynamic building simulation models: A case study

This study presents an original methodology for calibrating building energy models based on monitored data. An optimization-based approach was applied to a monitored test building coupling the building simulation program EnergyPlus with the optimization software GenOpt. An objective function was set to minimize the difference between the simulated and the monitored energy consumption at the hour time scale, varying the building model parameters selected at the beginning as the most influencing. After calibration, the observed heating energy consumption of the case study matched closely the monitored data, the model accuracy was verified according to the MBE and the Cv(RMSE) limit set by the ASHRAE guideline 14

Optmization-based calibration for dynamic building simulation models: A case study

This study presents an original methodology for calibrating building energy models based on monitored data. An optimization-based approach was applied to a monitored test building coupling the building simulation program EnergyPlus with the optimization software GenOpt. An objective function was set to minimize the difference between the simulated and the monitored energy consumption at the hour time scale, varying the building model parameters selected at the beginning as the most influencing. After calibration, the observed heating energy consumption of the case study matched closely the monitored data, the model accuracy was verified according to the MBE and the Cv(RMSE) limit set by the ASHRAE guideline 1

A global optimization technique for solid-liquid equilibrium calculations : application to calcium phosphate precipitation

Phase equilibrium calculations constitute an important problem for designing and optimizing crystallization processes. The Gibbs free energy is generally used as an objective function to find the quantities and the composition of phases at equilibrium. In such problems, the Gibbs free energy is not only complex but can have several local minima. This paper presents a contribution to handle this kind of problems by implementation of a hybrid optimization technique based on the successive use of a Genetic Algorithm (GA) and of a classical Sequential Quadratic Programming (SQP) method: the GA is used to perform a first search in the solution space and to locate the neighborhood of the solution. Then, the SQP method is employed to refine the solution. The basic operations involved in the design of the GA developed in this study (encoding with binary representation of real values, evaluation function, adaptive plan) are presented. Calcium phosphate precipitation which is of major interest for P-recovery from wastewater has been adopted as an illustration of the implemented algorithm

Méthodes d’évaluation du potentiel antioxydant dans les aliments

Maîtriser l’oxydation est indispensable pour gérer l’évolution des systèmes biologiques dans leur complexité, en particulier dans le cas des aliments dont la dégradation peut avoir des conséquences en sécurité alimentaire. Les différentes méthodes d’évaluation de l’activité antioxydante d’un additif alimentaire sont présentées après examen du contexte et des mécanismes d’oxydation. L’activité anti-oxydante est évaluée soit par le dosage des produits formés (en particulier des hydroperoxydes) par des techniques photométriques plus ou moins directes, soit par la mesure de l’efficacité du composé à piéger des radicaux libres. Les méthodes comparant le piégeage d’un additif avec celui d’un anti-oxydant de référence, le Trolox®, sont applicables à des produits variés quelle que soit l’hydrophilie ou l’hydrophobie du milieu.Oxidation control is necessary to manage the evolution of complex biological system, particularly in food whose degradation could have consequences on food security. After description of context and oxidation mechanisms, several analytical methods to evaluate the additive antioxidant potential are presented. This evaluation is performed either by quantification of products (in particular hydroperoxydes) using direct or indirect photometric techniques and chemical titration with suitable reactants or on the effectiveness to trap free radicals with modelized systems that can generate them. Methods based on the comparison of radical trapping ability between an additive and Trolox (particularly Trolox® equivalent antioxydant capacity, TEAC) can be applied to many products whatever the hydrophily or the hydrophobia of the medium

A hybrid optimization technique for improvement of P-recovery in a pellet reactor

Emphasis in recent years has been focused on improving processes which lead to enhanced phosphate recovery. This paper studies the precipitation features of calcium phosphate in a fluidized bed reactor in a concentration range between 50 et 4mg/L and establishes the conditions for optimum phosphate removal efficiency. For this purpose, a hybrid optimization technique based on Simulated Annealing (SA) and Quadratic Programming (QP) is used to optimize the efficiency of the pellet reactor. The efficiency is computed by coupling a simple agglomeration model with a combination of elementary systems representing basic ideal flow patterns (perfect mixed flow, plug flow,…). More precisely, the superstructure represents the hydrodynamics conditions in the fluidized bed. The “kinetic” constant is obtained for each combination. The two levels of the resolution procedure are as follows: at the upper level, SA generates different combinations and at the lower level, the set of parameters is identified by a QP method for each combination. The observed results show that a simple combination of ideal flow patterns is involved in the pellet reactor modeling, which seems interesting for a future control