http://195.251.240.227/jspui/handle/123456789/744 2026-05-30T00:47:12Z http://195.251.240.227/jspui/handle/123456789/9988 Title: Mechanistic model for the catalytic cracking of n-hexane over calcium aluminate catalysts for producing light alkenes Authors: Vasalos, Iacovos; Varvarezos, Dimitrios; Koulouris, Alexandros; Lemonidou, Aggeliki Abstract: A detailed chemical kinetic mechanism describing the thermal and catalytic cracking of n-hexane over a 12CaO·7Al2O3 catalyst is presented. The model was based on balance equations for both molecular and radical species describing an experimental bench scale fixed bed reactor system. Using Gear's algorithm for solving the differential equations, a satisfactory fit of experimental results was obtained both at low residence time where the alkenes are the main products and at high residence time where the formation of hydrogen plus carbon monoxide predominates. Description: Δημοσιεύσεις μελών--ΣΤΕΤ-Δ--Τμήμα Τεχνολογίας Τροφίμων--2001 2001-08-02T00:00:00Z http://195.251.240.227/jspui/handle/123456789/9977 Title: Wave-Nets : novel learning techniques, and the induction of physically interpretable models Authors: Bakshi, Bhavik; Koulouris, Alexandros; Stephanopoulos, George Abstract: A wavelet network, or Wave-Net is a connectionist network that combines the mathematical rigor and multiresolution character of wavelets with the adaptive learning of artificial neural networks. In this paper, we present some novel techniques for training and adaptation of Wave-Nets, and describe the induction of models that may be physically interpretable, and may provide useful insight into the system being modeled. Learning from empirical data is formulated as a constrained optimization problem. This formulation illustrates the complexity of the learning problem, and highlights the decision variables and the simplifying assumptions necessary for a practical learning methodology. Techniques for Wave-Net training and adaptation are developed for minimizing the L2 or L(infinity) norms. Minimizing the L(infinity) norm is particularly relevant for solving control problems. The connection between Wave-Net parameters, and the error of approximation is derived using the principles of frame theory. The performance of Wave-Nets for different training methodologies, and basis functions is compared via case studies. Wave-Nets with Haar wavelets as activation functions are well-suited for problems where the output consists of a finite set of discrete values, as in classification problems. The mapping learned by Haar Wave-Nets may be represented as simple if-then rules, which provide an explicit and physically meaningful relationship between inputs and outputs. The relationship of learning by Haar Wave-Nets with other rule induction techniques, such as decision trees is explored. Description: Δημοσιεύσεις μελών--ΣΤΕΤ-Δ--Τμήμα Τεχνολογίας Τροφλιμων--1994 1994-04-04T00:00:00Z http://195.251.240.227/jspui/handle/123456789/9966 Title: A Phenomena-Oriented Environment for Teaching Process Modeling : Novel Modeling Software and Its Use in Problem Solving Authors: Geurts, Kevin; Bieszczad, Jerry; Dahm, Kevin; Goodeve, Peter; Stephanopoulos, George; Foss, Alan; Koulouris, Alexandros Abstract: Discusses a program that offers students a phenomenon-oriented environment expressed in the fundamental concepts and language of chemical engineering such as mass and energy balancing, phase equilibria, reaction stoichiometry and rate, modes of heat, and species transport. (CCM) Description: Δημοσιεύσεις μελών--ΣΤΕΤ-Δ--Τμήμα Τεχνολογίας Τροφίμων--199 1999-01-01T00:00:00Z http://195.251.240.227/jspui/handle/123456789/9995 Title: Throughput analysis and debottlenecking of integrated batch chemical processes Authors: Koulouris, Alexandros; Calandranis, John; Petridis, Dimitris Abstract: In batch plants, as we attempt to increase annual throughput, we run into bottlenecks that are either equipment or resource (e.g. utilities, labor) related. Throughput bottlenecks are equipment or resources that limit the amount of product produced per batch. Scheduling bottlenecks are units or resources that limit the number of batches that can be processed per year or campaign. In this paper, we present a systematic simulation-based methodology for identifying bottlenecks in batch processing and a strategy for eliminating them. The decision-making process is based on a set of operation-related variables that are used to indicate the presence of bottlenecks. The implementation of the methodology is demonstrated with the use of a synthetic pharmaceutical example. Description: Δημοσιεύσεις μελών--ΣΤΕΤ-Δ--Τμήμα Τεχνολογίας Τροφίμων--2001 2001-10-23T00:00:00Z