Current Issue : January - March Volume : 2012 Issue Number : 1 Articles : 5 Articles
A model-based predictive control system is designed for a copolymerization reactor. These processes typically have such a high nonlinear dynamic behavior to make practically ineffective the conventional control techniques, still so widespread in process and polymer industries. A predictive controller is adopted in this work, given the success this family of controllers is having in many chemical processes and oil refineries, especially due to their possibility of including bounds on both manipulated and controlled variables. The solution copolymerization of methyl methacrylate with vinyl acetate in a continuous stirred tank reactor is considered as an industrial case study for the analysis of the predictive control robustness in the field of petrochemical and polymer production. Both regulatory and servo problems scenarios are considered to check tangible benefits deriving from model-based predictive controller implementation....
This paper summarizes some applications of ultrasonic vibrations regarding heat transfer enhancement techniques. Research literature is reviewed, with special attention to examples for which ultrasonic technology was used alongside a conventional heat transfer process in order to enhance it. In several industrial applications, the use of ultrasound is often a way to increase productivity in the process itself, but also to take advantage of various subsequent phenomena. The relevant example brought forward here concerns heat exchangers, where it was found that ultrasound not only increases heat transfer rates, but might also be a solution to fouling reduction....
Sugar is a highly 'politicized' commodity in India and covered under the Essential Commodity Act, 1955. In Indian Sugar industry, the government regulates raw material cost and announces a statuary minimum price (SMP) for the purchase of sugarcane by the sugar firms before the start of the sugar year.\r\nSugar has a number of non-food uses. One of these is in the pharmaceutical industry. There is a significant use of sugar in the more traditional areas, e.g. tablets, syrups and pallets. Hence sugar can be good raw material for the synthesis of novel ecofriendly polymers. This sugar based polymers are easily synthesized by conventional method and by microwave synthesis technique and compared with each other by its method of analysis, characterization and by its application in replacement of petroleum products which are abundantly used in powder and liquid detergent....
Fermentation processes by nature are complex, time-varying, and highly nonlinear. As dynamic systems their modeling and further high-quality control are a serious challenge. The conventional optimization methods cannot overcome the fermentation processes peculiarities and do not lead to a satisfying solution. As an alternative, genetic algorithms as a stochastic global optimization method can be applied. For the purpose of parameter identification of a fed-batch cultivation of S. cerevisiae altogether four kinds of simple and four kinds of multipopulation genetic algorithms have been considered. Each of them is characterized with a different sequence of implementation of main genetic operators, namely, selection, crossover, and mutation. The influence of the most important genetic algorithm parametersââ?¬â?generation gap, crossover, and mutation rates hasââ?¬â?been investigated too. Among the considered genetic algorithm parameters, generation gap influences most significantly the algorithm convergence time, saving up to 40% of time without affecting the model accuracy....
Ultrasonic velocity, density, viscosity and refractive index measurements of caffeine in 0.1M, 0.05M and 0.025M aqueous solutions of sodium chloride, potassium chloride, calcium chloride and magnesium chloride have been carried out at 303.15K. From these experimental data isentropic compressibility, acoustic impendence, relative association, free length, apparent molar volume, apparent molar isentropic compressibility and molar refraction of caffeine at infinite dilution in presence of electrolytes are evaluated. These values have been employed to explain molecular association and solute-solvent interaction through hydrogen bonding and solvation. Viscosity data have been analyzed in the light of Jones-Dole equation and the constants A and B have been estimated and interpreted in terms of ion-ion and ion-solvent interactions occurring in solutions.\r\nKeywords: ultrasonic velocity, density, viscosity, refractive index, solute-solvent, solute-solute interaction....
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