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Abstract

Aesthetic and utilitarian properties of traditional ceramic wares as well as engineering properties of modern advanced ceramics are attained by maintaining an optimum temperature-time-atmosphere relationship, called firing schedule, in the kiln. The contribution of modern thermal analysis (TA) techniques such as TG/DTG, TG/EGA, TG/MS, DTA, DSC, TDA, etc. in 1) optimizing production steps by raw material quality control, by studying binder burn out, product densification, 2) in simulating appropriate preheating, firing and cooling schedules as well as 3) in developing shorter firing cycles has been extensively reported in recent literature. The paper will first discuss theoretical curves and energy required for ceramic firing and present from the literature selected examples of applications of thermal analysis in ceramic technology.

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Abstract  

When chemical reactions are performed in semi-batch mode and the reaction rate is relatively low, the reactant added may be accumulated. The resulting thermal accumulation is of major concern regarding process safety, as a fault in the cooling system may lead to a run-away reaction. The feed rate in semi-batch processes is usually constant, but this paper discusses methods of optimizing the feed rate interactively, based on the measured heat flow and the calculated amount of compound that has actually reacted. The prerequisite of such procedures is to run the experiments in a reaction calorimeter in which the heat flows can be measured accurately and continuously. For this purpose a ChemiSens reaction calorimeter CPA202, which is calibration free and gives stable, flat ‘zero-line-type’ baselines, was employed.

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Journal of Thermal Analysis and Calorimetry
Authors: R. Hilfiker, J. Berghausen, F. Blatter, A. Burkhard, S. De Paul, B. Freiermuth, A. Geoffroy, U. Hofmeier, C. Marcolli, B. Siebenhaar, M. Szelagiewicz, A. Vit, and M. von Raumer

Abstract  

Crystal structure (polymorphism) as well as crystal shape (morphology) and size have a huge practical and commercial impact on active substances all the way from research to manufacture of the final product. For an optimal development process, it is important to have an integrated approach to these issues ranging from a systematic polymorphism screening to a controlled scale-up of the crystallization process. The polymorphism program has to be tailored according to the development stage. Particularly suitable for an early development stage is a high-throughput polymorphism screening, which is the basis for a more thorough investigation if the product proceeds further in development. Such a comprehensive polymorphism investigation involves further crystallization experiments and extensive physicochemical characterization of the various forms. In this article the high-throughput polymorphism screening method that we have developed is described. Using carbamazepine as an example, the power of this high-throughput polymorphism screening system is demonstrated. Not only were all published forms found, but also new forms were identified. In the second part of the article, important considerations for crystallization optimization are discussed, again using the example of carbamazepine.

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experiment ( global optimum ) is achieved [ 1–3 ]. The goal of method optimization is to find the conditions under which the examined system gives the maximal or minimal response, as well as to define the mathematical model that establishes the relationship

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Optimization of microwave-assisted extraction (MAE) as a method of sample preparation in thin-layer chromatographic (TLC) analysis of a herbicide mixture is described. The extraction was optimized with regard to amount of solvent, duration of microwave extraction, and temperature. In the proposed method the experimental-design technique was used to design initial experiments and a genetic algorithm (GA) was used in the optimization procedure. The general objective was to test a mathematical tool which could facilitate optimization. The optimization procedure was tested in the TLC determination of a mixture of the herbicides atrazine and simazine; determination of recovery revealed results were satisfactory. The GA proved to be an optimization procedure which can be successfully applied to optimization of MAE experiments.

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.05). All data are presented as the mean with the standard deviation. In the present study, Design-Expert software version 10.0.7.0 (Statease Inc., Minneapolis, USA) was used for the optimisation of modification parameters of amaranth starch. 3 Results and

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as a probe to evaluate the photocatalytic efficiency of the TiO 2 /CS system under low energy light source. Therefore, the objectives of this study were to fabricate, optimize and apply a simple layer-by-layer TiO 2 /CS system consisting of TiO 2 and

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Abstract  

Information properties of analytical results together with other important parameters especially economic ones can be used for the optimization of analytical procedures. Therefore, we have proposed a computational technique for the optimization of multielement neutron activation analysis (NAA) based on the information content and profitability. The optimization starts with the prediction of the -ray spectra to be expected during analysis under given experimental conditions (sample size, irradiation, decay and counting times etc.) and with the calculation of detection and determination limits. In the next step, the information contents for the determination of particular elements and for the simultaneous determination of element groups are computed. The information content depends or is closely connected with such properties of the method as selectivity, sensitivity, precision, accuracy and, as in the other cases of trace analysis, also with the detection limit. Then, the information profitability (IP) taking into account the information content and relevance (appreciation of specific information according to its contribution to the solution of a given problem) together with economic aspects can be calculated. This function can be used for the optimization of a particular NAA procedure, for the mutual comparison of different variants of NAA and also for the comparison with other analytical methods. The use of information profitability for the optimization of NAA is shown on a practical example of the INAA analysis of urban particulate matter SRM 1648 produced by NBS (USA).

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Abstract  

An activation analysis procedure has been suggested which includes correction of the measurement time in accordance with the normalized error by processing the date during observation with subsequent optimization of the activation and cooling times. Such a procedure enables one to intensify the analysis providing the analytical error is normalized. A mathematical description of the procedure is given, and the optimization of the components of the measurement and their treatment in accordance with the normalized error is performed. This procedure is most efficient for analysis of a great number of samples similar in elemental composition, i.e. in systems used in industry. The measurement may also be applied in scientific studies. The features concerning application of the optimized measurements in activation analysis with various sources of activating particles, as well as in other radioanalytical methods, are considered.

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Qualitative identification of Cu, Sn, Pb, Ni, and Fe in Cu-alloys is presented. The method involves anodic sampling of alloys, separation and identification by thin-layer chromatography (TLC). The powerful desktop-computer tool makes it easy to optimize ternary solvent mixtures. Optimization was performed graphically by means of R si≥1 as a selected separation criterion. Mobile phase composition for optimal separation was determined as MeOH−HCl−H2O (60:35:5, v/v). The method was applied to Persian helmet as real sample.

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