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Synthesis of regional networks for biomass and biofuel production
Hon Loong Lam, 2010, doktorska disertacija

Opis: This thesis presents two different approaches to the synthesis of regional networks for biomass and biofuel production and supply: Mathematical Programming and Graph Theoretic approach. The optimisation criterion for both approaches is the maximisation of profit. The first approach is based on a generic optimisation model of biomass production and supply networks. This superstructure approach is based on a flexible number of network layers: plantation, collection using a pre-treatment, process, and consumption. A Mixed Integer Linear Programming (MILP) model has been successfully developed during this work. However, the solution of this biomass production network model is very challenging due to the large sizes of the networks and the number of interconnections. The huge number of redundant variables reduces model efficiency (time taken to solve the model and the interpretation of the results). This model when representing very large size networks cannot be solved over a reasonable time even by professional mathematical programming software tools. Several model-size reduction techniques are therefore proposed for the solution of large-scale networks. In particular, methods are proposed for (i) reducing the connectivity within a biomass supply chain network by setting the maximum allowable distance between the supply zones to the collection centres, (ii) eliminating unnecessary variables and constrains to reduce the zero-flows in the full model, and (iii) aggregating the network and hence the synthesis process by merging the collection centres. The network synthesis is also carried out by P-graph (Process Graph) tools. P-graph is a directed bipartite graph, having two types of vertices — one for operating units and another for those objects representing material or energy flows/quantities. In this procedure, firstly a maximum feasible superstructure for biomass production network is generated from which the optimal structure is then selected by the Branch and Bound method. This graph-based method clearly shows where, how, and what kind of material and energy carriers will be transferred from one supply chain layer to another. In order to test the efficiency of the model, a small regional renewable network problem was solved using both methods. Their performances were tested and the results confirmed the applicability on a regional scale. The proposed model-size reduction techniques were also tested. A large-scale regional case study was created to demonstrate these techniques. The results are very positive and some suggestions for future work are given in the conclusion.
Ključne besede: Biomass and bioenergy network synthesis, Model-size reduction techniques, Mathematical Programming, MILP, P-Graph
Objavljeno: 06.01.2011; Ogledov: 2462; Prenosov: 83
.pdf Celotno besedilo (4,25 MB)

Iztok Fister, 2011, diplomsko delo/naloga

Opis: Measuring time in mass sporting competitions is, typically, performed with a timing system that consists of a measuring technology and a computer system. The first is dedicated to tracking events that are triggered by competitors and registered by measuring devices (primarily based on RFID technology). The latter enables the processing of these events. In this paper, the processing of events is performed by an agent that is controlled by the domain-specific language, EasyTime. EasyTime improves the flexibility of the timing system because it supports the measuring of time in various sporting competitions, their quick adaptation to the demands of new sporting competitions and a reduction in the number of measuring devices. Essentially, we are focused on the development of a domain-specific language. In practice, we made two case studies of using EasyTime by measuring time in two different sporting competitions. The use of EasyTime showed that it can be useful for sports clubs and competition organizers by aiding in the results of smaller sporting competitions, while in larger sporting competitions it could simplify the configuration of the timing system.
Ključne besede: domain-specific languages, programming languages, RFID technology
Objavljeno: 09.06.2011; Ogledov: 3180; Prenosov: 384
.pdf Celotno besedilo (2,08 MB)

Yield strength modelling of formed material using evolutionary computational method
Leo Gusel, Rebeka Rudolf, 2009, izvirni znanstveni članek

Opis: In this paper we propose an evolutionary computation approach for the modelling of yield strength in formed material. One of the most general evolutionary computation methods is genetic programming, which was used in our research. Genetic programming is an automated method for creating a working computer program from a problemćs high-level statement. Genetic programming does this by genetically breeding a population of computer programs using the principles of Darwinianćs natural selection and biologically inspired operations. During our research, material was cold formed by drawing using different process parameters and then determining yield strengths (dependent variable) of the specimens. On the basis of a training data set, various different genetic models for yield strength distribution were developed during simulated evolution. The accuracies of the best models were proved by a testing data set and comparing between the genetic and regression models. The research showed that very accurate genetic models can be developed by the proposed approach.
Ključne besede: metal forming, yield strength, genetic programming, modelling
Objavljeno: 31.05.2012; Ogledov: 1182; Prenosov: 21
URL Povezava na celotno besedilo

Heat integration between two biodiesel processes using a simple method
Anita Kovač Kralj, 2008, izvirni znanstveni članek

Opis: Biodiesel is a clean-burning alternative fuel, produced from domestic, renewable resources. Biodiesel can be blended at any level with petroleum diesel to create a biodiesel blend. It can be used in compression-ignition (diesel) engines with little or no modification. Biodiesel is simple to use, biodegradable, nontoxic, and essentially free of sulfur and aromatics. This paper presents heat integration between two biodiesel processes. Biodiesel can be produced by the esterification of different fatty acids (high and low boiling point) with alcohols. This simple method for heat integration is based on three possible steps. Simultaneous integration between processes can be performed using a stagewise model with a mixed integer nonlinear programming (MINLP) algorithm (step 3), which can include alternatives suggested by pinch analysis of heat transfer between the processes (step 2). The internal integration of individual processes can be performed in step 1. The fraction can be calculated for maximum integration between processes. Integration between the processes can be carried out using all three steps or by the first and third steps or by the last step only, depending on the problems' complexities. This method includes streams of different processes which are heated or cooled using a utility only. The existing heaters and coolers can be left unchanged in their original processes or can be used for integrating heat between processes, with hot and cold utilities being saved. This approach is illustrated by integrating two simulated biodiesel processes.The objective was to maximize additional annual profit for integration between processes by USD8300/a.
Ključne besede: chemical processing, biodiesel producing, heat integration, nonlinear programming
Objavljeno: 31.05.2012; Ogledov: 1127; Prenosov: 29
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Modeling of impact toughness of cold formed material by genetic programming
Leo Gusel, Miran Brezočnik, 2006, izvirni znanstveni članek

Opis: In the paper, an approach completely different from the conventional methods for determination of accurate models for the change of properties of cold formed material, is presented. This approach is genetic programming (GP) method which is based on imitation of natural evolution of living organisms. The main characteristic of GP is its non-deterministic way of computing. No assumptions about the form and size of expressions were made in advance, but they were left to the self organization and intelligence of evolutionary process. First, copper alloy rods were cold drawn under different conditions and then impact toughness of cold drawn specimens was determined by Charpy tests. The values of independent variables (effective strain, coefficient of friction) influence the value of the dependent variable, impact toughness. On the basis of training data, different prediction models for impact toughness were developed by GP. Only the best models, gained by genetic programming were presented in the paper. Accuracy of the best models was proved with the testing data set. The comparison between deviation of genetic model results and regression model results concerning the experimental results has showed that genetic models are more precise and more varied then regression models.
Ključne besede: metal forming, genetic programming, evolutionary computing, impact toughness, copper alloy, modelling
Objavljeno: 30.05.2012; Ogledov: 1222; Prenosov: 41
URL Povezava na celotno besedilo

Study of crosslinking efficiency of cotton cellulose by different physical-chemical methods and genetic programming
Olivera Šauperl, Miran Brezočnik, 2006, izvirni znanstveni članek

Opis: We have investigated the crosslinking effect of unmercerized and mercerized cotton celluose crosslinked with different BTCA mass fractions in the impregnation bath. Crosslinking efficiency was analyzed using FT-IR spectroscopy, water retention capacity method, tensiometry and the methylene blue method. On the basis of the experimental data which was obtained with theseparate physical-chemical methods, different prediction models for crosslinking efficiency was developed. Modelling was taken out with the genetic programming method. Research shows good accordance of the experimentaldata with the genetic models.
Ključne besede: textile fibres, cotton, cellulose, crosslinking, FTIR spectroscopy, methylene blue method, water retention capacity, tensiometry, genetic programming
Objavljeno: 30.05.2012; Ogledov: 1178; Prenosov: 21
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Intelligent programming of CNC turning operations using genetic algorithm
Jože Balič, Miha Kovačič, Boštjan Vaupotič, 2006, izvirni znanstveni članek

Opis: CAD/CAM systems are nowadays tightly connected to ensure that CAD data can be used for optimal tool path determination and generation of CNC programs for machine tools. The aim of our research is the design of a computer-aided, intelligent and genetic algorithm(GA) based programming system for CNC cutting tools selection, tool sequences planning and optimisation of cutting conditions. The first step is geometrical feature recognition and classification. On the basis of recognised features the module for GA-based determination of technological data determine cutting tools, cutting parameters (according to work piece material and cutting tool material) and detailed tool sequence planning. Material, which will be removed, is split into several cuts, each consisting of a number of basic tool movements. In thenext step, GA operations such as reproduction, crossover and mutation are applied. The process of GA-based optimisation runs in cycles in which new generations of individuals are created with increased average fitness of a population. During the evaluation of calculated results (generated NC programmes) several rules and constraints like rapid and cutting tool movement, collision, clamping and minimum machining time, which represent the fitness function, were taken into account. A case study was made for the turning operation of a rotational part. The results show that the GA-based programming has a higher efficiency. The total machining time was reduced by 16%. The demand for a high skilled worker on CAD/CAM systems and CNC machine tools was also reduced.
Ključne besede: CNC programming, genetic algorithm, intelligent CAM, turning, tool path generation
Objavljeno: 30.05.2012; Ogledov: 1267; Prenosov: 37
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