Tuomas Koiranen

Case-based reasoning system for mixing equipment selection

Abstract The use of case-based reasoning in the mixing equipment selection is promising. Its main advantage is use of high quality, verified knowledge and easiness of updating. The main functions of the system are a systematic documentation of the cases and an accumulation of experience. Case-based reasoning (CBR) is an alternative approach to rule-based and object-oriented systems. CBR is based on the retrieval and adaptation of the old solutions to the new problems. There are five steps in CBR: presentation of a new problem, retrieval of the most similar cases, adaptation of the most similar old solutions, validation of the current solution and updating of the system by adding the verified solution to the database of cases. The main advantages of CBR are the easy knowledge acquisition and simple explanatory system. Other important features are easy maintenance and learning capabilities. Determination of the most important features in mixing equipment selection and their importance is studied in this work. The main features discussed are liquid volume and rheological parameters, content of particles and/or gas bubbles as well as the type of application and the aim of the process. The retrieval search has been organized by using flat memory and serial search. The following data are given as the output values of the system: impeller and entering type, scale of agitation, mixing power, number of impellers and geometry of tank. An example of CBR applications to the mixing equipment selection in wastewater industry is given.

Adaptation phase in case-based reasoning system for process equipment selection

Abstract Case-based reasoning (CBR) is an alternative approach to rule case-based and object-oriented systems. CBR is based on the retrieval and adaptation of the old solutions to the new problems. There are five steps in CBR: introduction of a new problem, retrieval of the most similar cases, adaptation of the most similar solutions, validation of the current solution and updating of the system by adding the verified solution to the database of cases. Adaptation phase is a crucial element in obtaining a good quality solutions. Up to now, there were no proposals for the automatization of the adaptation phase in the systems for the equipment selection. In the presented system the retrieval search has been organized by using flat memory and serial search. The adaptation is realized by the fuzzy calculation of the membership function built on the basis of the most similar retrieved cases. The main advantage of this system is use of high quality, verified knowledge and easiness of updating.

Concurrent engineering: Robust design in fuzzy environment

Abstract The question of robust designis formulated and solved as fuzzy optimization problem. The process equations are equality constraints. The nonequality constraints are the criteria resulting from the “house of quality” method. A numerical example is presented to illustrate the basic idea of the robust design with fuzzy parameters.

Valorization of Lignin by Partial Wet Oxidation Using Sustainable Heteropoly Acid Catalysts

The production of carboxylic acids by partial wet oxidation of alkali lignin at elevated temperatures and pressures was studied experimentally. Two different heteropoly acids, phosphotungstic acid (H3PW12O40) and phosphomolybdic acid (H3PMo12O40), were used to catalyze the oxidation of lignin under hydrothermal conditions. Factors influencing the total yield of carboxylic acids formed during the partial oxidation of lignin were investigated. Formic, acetic and succinic acids were the major products identified. Of the two catalysts used, phosphomolybdic acid gave the most promising results, with carboxylic acid yields and lignin conversions of up to 45% and 95%, respectively.

Hybrid, fuzzy and neural adaptation in case- based reasoning system for process equipment selection

Adaptation is the most difficult step in case-based reasoning. There are no general methods for the modification of the retrieved cases to fit the actual design problem. The use of new, context independent technique is an important research subject. In the paper, a hybrid adaptation system is proposed. Its main components are based on fuzzy logic and neural networks. The applicability of the proposed adaptation methods is examined in preliminary design of mixing system.

Object-oriented knowledge based systems for process equipment selection

Abstract Two protoytype knowledge-based systems for shell and tube heat exchanger and liquid mixing equipment selection (HESES and MIXES) have been developed by use of NEXPERT OBJECT and TOOLBOOK on a PC computer. In the whole system developing procedure the object-oriented approach was used and the object matrix method was proposed to make knowledge acquisition and programming more reasonable, flexible and easier. The object matrixes are stored in MS EXCEL spreadsheet files that constitute a primary expert interface for knowledge modification. The knowledge bases are organized by a multi-knowledge based technique and the message is transferred among them through a blackboard.

Experimentally Validated CFD Model for Gas-Liquid Flow in a Round-Bottom Stirred Tank Equipped with Rushton Turbine

Abstract Hydrodynamics of gas-liquid flow in a round-bottom stirred tank is modelled at two gas flow rates, constant bubble size and agitator speed of 300 rpm. A round-bottom tank equipped with four baffles and a Rushton turbine was chosen to represent a typical reactor used in hydrometallurgical processes operating under pressure. The applicability of different momentum interchange models and the Realizable k-ε, SST k-ω, and RSM turbulence models was studied using CFD software. The results were compared and validated against experimental data from Particle Image Velocimetry measurements by means of liquid and gas velocity distributions. In addition, energy balance between power input and dissipation energy was compared for the different turbulence models. The CFD model was found to be in good agreement with the measurements. Of the turbulence models studied, the Realizable k-ε model showed best agreement with the measured velocity profiles. Popular drag force models proposed in the literature were assessed, as was the influence of inclusion of non-drag forces. Gas flow was found to affect the liquid phase flow in the tank by generating an additional secondary circulation loop in the upper part of the reactor.

Carbon nanotube supercellulose supercapacitor

Supercellulose gel and single-wall carbon nanotubes (SWCNTs) were used for the creation of binder-free electrode for supercapacitor application and the properties of the electrode were investigated in aqueous electrolyte. Two layers of the formed composite material were inserted on graphite current collectors and separated from each other by a separator to create a supercapacitor prototype for measurements. Different concentrations of SWCNTs were studied and 65% concentration of SWCNTs resulted in the highest specific capacitance.

Spreadsheet version of knowledge-based system for mixing tanks selection

Mixing is a common unit operation and there are a great variety of the possible systems to be mixed and the configurations 10 be applied. All this makes the selection of mixing equipment as an important field for the expert systems application. This paper presents the spreadsheet-based expert system for the selection of stirred tank vessels. The presented system has been designed to work in the narrow field of expertize. The general methodology of the mixers selection is presented first. The program structure and the implementation aspects are discussed further. The last part of the paper presents the example of the system application, comments about the obtained solutions and summary. The expert systems implemented in spreadsheet programs are not very popular and there is a common believe that their capabilities are strongly limited. However, our experience proved that this type of expert system could be very useful in the equipment selection. We recommend the development of the expert systems starting f...

Erratum: Demesa, A.G.; et al. Valorization of Lignin by Partial Wet Oxidation Using Sustainable Heteropoly Acid Catalysts. Molecules 2017, 22, 1625

The authors would like to make the following correction to their published paper [1]. [...].