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Optimization of a gas turbine in the methanol process, using the NLP model
Anita Kovač Kralj, Peter Glavič, 2007, izvirni znanstveni članek

Opis: Heat and power integration can reduce fuel usage, CO2 and SO2 emissions and, thereby, pollution. In the simultaneous heat and power integration approach and including additional production, the optimization problem is formulated using a simplified process superstructure. Nonlinear programming (NLP) contains equations which enable structural heat and power integration and parametric optimization. In the present work, the NLP model is formulated as an optimum energy target of process integration and electricity generation using a gas turbine with a separator. The reactor acts as a combustion chamber of the gas turbine plant, producing high temperature. The simultaneous NLP approach can account for capital cost, integration of combined heat and power, process modification, and additional production trade-offs accurately, and can thus yield a better solution. It gives better results than non-simultaneous methods. The NLP model does not guarantee a global cost optimum, but it does lead to good, perhaps near optimum designs. This approach is illustrated by an existing, complex methanol production process. The objective function generates a possible increase in annual profit of 1.7 M EUR/a.
Ključne besede: chemical processes, methanol, simultaneous optimization, NLP, cogeneration, gas turbine
Objavljeno: 31.05.2012; Ogledov: 1362; Prenosov: 60
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A comparison of BPMN notation and natural language understandability
Jernej Huber, Aleš Živkovič, Marjan Heričko, 2011, objavljeni znanstveni prispevek na konferenci

Opis: In this paper, we explored the understandability of BPMN notation as compared with the understandability of natural language. We conducted an experiment in which we examined the results of students who were completing two different types of questionnaires. Students from the first group analyzed BPMN diagrams, while others analyzed an unstructured text. The text and BPMN diagrams were from identical problem domains and both groups of students answered the same questions. We compared the results and conducted a statistical analysis using a t-test with independent samples. Because we were able to classify students according to their prior knowledge of BPMN notation, we also conducted a one-way ANOVA test and performed a detailed analysis of the collected data.
Ključne besede: business processes, BPMN diagrams, natural language
Objavljeno: 01.06.2012; Ogledov: 1044; Prenosov: 43
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Feasibility and rationale of introducing layers into business process models
Gregor Polančič, Gregor Jošt, Jari Soini, 2011, objavljeni znanstveni prispevek na konferenci

Opis: Business Process Model and Notation (BPMN) is the leader and de-facto standard in business process modeling, a sub-discipline of business process management. While BPMN's objectives are to be expressive, widely understood, interchangeable and executable, it has also became rich and complex. The objective of this article is to present an idea of lowering the complexity of BPMN by applying layers into BPMN based process models. As presented in the article, layers are the remaining complexity management approach, which has not been implemented in BPMN yet. The focal part of the article is a SWOT analysis of applying layers into business process models, as well as the future work and challenges which need to be solved in order to reach our research goal - increasing the objective and subjective understandability of BPMN based process models.
Ključne besede: business processes, business process management, business process model and notation, BPMN
Objavljeno: 01.06.2012; Ogledov: 1003; Prenosov: 33
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Enterprise : performance and business processes
Valentina Gečevska, Franc Čuš, Radmil Polenakovik, Paolo Chabert, 2011, izvirni znanstveni članek

Opis: This article proposes a scenario of Product Lifecycle Management (PLM), as a innovative business strategy based on the analysis of business drivers, industry requirements, limit of current solution, and recent state-of-the-art review in the domain related to PLM. Potential industrial impact of the developed PLM technology solutions is analyzed. It is hoped that the proposed PLM technology solutions will form the frontier basis for further research, development, and application of PLM systems to quickly adapt to the dynamic changing market for industry companies to pursue the most advanced competitiveness. This article presents a process oriented framework to support effective PLM implementation with a set of lifecycle oriented business process reference models which links the necessary fundamental concepts, enterprise knowledge and software solutions to effectively deploy PLM.
Ključne besede: Product Lifecycle Management, PLM, innovation, business processes, technology
Objavljeno: 01.06.2012; Ogledov: 1235; Prenosov: 16
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Laundry wastewater treatment using coagulation and membrane filtration
Sonja Šostar-Turk, Irena Petrinić, Marjana Simonič, 2005, izvirni znanstveni članek

Opis: This paper presents the results obtained from laundry wastewater treatment using conventional methods namely precipitation/coagulation and the flocculation process with adsorption on granular-activated carbon (GAC) and an alternative method, membrane filtrations, namely ultrafiltration (UF) and reverse osmosis (RO). Chemical analyses showed that parameter values of untreated wastewater like temperature, pH, sediment substances, total nitrogen and phosphorous, COD, BOD5, and the amount of anion surfactants had been exceeded in regard to Slovenian regulation. These regulations can be used as requirements for wastewater reuse and make treated wastewater an available source for the existing water supply. The study of conventional treatment was based on a flocculation with Al2(SO4)3 18H2O and adsorption on GAC. Membrane filtrations were studied on a pilot wastewater treatment plant: ultrafiltration (UF) and reverse osmosis (RO) units. The membranes used in this experiment were ceramic UF membrane and spiral wounded - polyethersulfone- RO membranes. The quality of the wastewater was improved by both methods and the specifications of a concentration limit for emission into water were confirmed. The disadvantage of GAC is that there is no possibility of any kind of selection, which is essential for recycling and re-use, while permeate coming from RO met the required regulation as well as requirements for reusing in washing process. However, the economical analyses showed that the membrane filtrations are more expensive compared to the GAC treatment process.
Ključne besede: laundries, washing of textiles, waste waters, advanced oxidation processes, membrane technology, membrane filtration, coagulation
Objavljeno: 01.06.2012; Ogledov: 1534; Prenosov: 81
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Encyclopedia of complexity and systems science
slovar, enciklopedija, leksikon, priročnik, atlas, zemljevid

Opis: Encyclopedia of Complexity and Systems Science provides an authoritative single source for understanding and applying the concepts of complexity theory together with the tools and measures for analyzing complex systems in all fields of science and engineering. The science and tools of complexity and systems science include theories of self-organization, complex systems, synergetics, dynamical systems, turbulence, catastrophes, instabilities, nonlinearity, stochastic processes, chaos, neural networks, cellular automata, adaptive systems, and genetic algorithms. Examples of near-term problems and major unknowns that can be approached through complexity and systems science include: The structure, history and future of the universe; the biological basis of consciousness; the integration of genomics, proteomics and bioinformatics as systems biology; human longevity limits; the limits of computing; sustainability of life on earth; predictability, dynamics and extent of earthquakes, hurricanes, tsunamis, and other natural disasters; the dynamics of turbulent flows; lasers or fluids in physics, microprocessor design; macromolecular assembly in chemistry and biophysics; brain functions in cognitive neuroscience; climate change; ecosystem management; traffic management; and business cycles. All these seemingly quite different kinds of structure formation have a number of important features and underlying structures in common. These deep structural similarities can be exploited to transfer analytical methods and understanding from one field to another. This unique work will extend the influence of complexity and system science to a much wider audience than has been possible to date.
Ključne besede: cellular automata, complex networks, computational nanoscience, ecological complexity, ergodic theory, fractals, game theory, granular computing, graph theory, intelligent systems, perturbation theory, quantum information science, system dynamics, traffic management, chaos, climate modelling, complex systems, dynamical sistems, fuzzy theory systems, nonlinear systems, soft computing, stochastic processes, synergetics, self-organization, systems biology, systems science
Objavljeno: 01.06.2012; Ogledov: 1514; Prenosov: 74
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Multi-criteria optimization in a methanol process
Anita Kovač Kralj, Peter Glavič, 2009, izvirni znanstveni članek

Opis: Opportunities for additional profit in retrofits depend very much on the existing plant structure, its parameters and energy system. Combined production of heat flow rate, power and chemical products can improve process efficiency. This paper presents an application of the nonlinear programming (NLP) optimization techniques, including increased chemical product output, heat integration and electricity cogeneration by changing amount flow ratios of raw material, and modifying the separation and reaction systems. The existing NLP model has been extended with basic chemical kinetics, including the effects of changing raw material flow rate ratios on product yield. A case studied methanol plant was optimized using the NLP model developed earlier by including an additional flow rate of hydrogen (H2), decreasing flowrate of high-pressure steam in crude methanol recycling, and increasing methanol production by 2.5%. The potential additional profit from the cogeneration and additional methanol production was estimated to be 2.51 MEUR/a.
Ključne besede: chemical processes, methanol, simultaneous optimization, NLP, cogeneration, flow rate ratios
Objavljeno: 01.06.2012; Ogledov: 1124; Prenosov: 65
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A model of simulation environment for prediction and optimisation of production processes
Igor Drstvenšek, Mirko Ficko, Ivo Pahole, Jože Balič, 2004, izvirni znanstveni članek

Opis: Paper describes means and methods for computer based optimisation of production processes using a new approach based on technological database (TDB) with genetic algorithm incorporated into a database management system (DBMS). The TDB serves as a store of tools and machine tools from which they can be assigned to different work operations. Work operations are basic entities of orders placed into queues. The goal of the model is to find available resources from the TDB in order to empty the queue in shortest time with lowest costs. To this purpose the model consist the technological database whose DBMS includes a genetic algorithm based optimiser. It checks the orders queue and searches for appropriate combinations of tools and machine tools from the TDB, which can be combined into needed work operations. It also performs an optimisation of time and costs according to so called static parameters of tools and machine tools.
Ključne besede: production processes, simulation, process planning, technological databases, genetic algorithms
Objavljeno: 01.06.2012; Ogledov: 1069; Prenosov: 63
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Databases for technological information systems
Franc Čuš, Bogomir Muršec, 2004, izvirni znanstveni članek

Opis: Organization of tool management for mixed production includes today, in particular, the computer-supported management and organization of the flow of tools and data on them. The system supports the entire flow of tools in a production process including the tool store management, commissioning, mounting, dismantling and pre-setting of tools. The system contains the management of the tool database with all vital data on tools and ensures adaption of production requirements for meeting the needs for tools. The integral model for the selection of optimal cutting conditions in the computer aided tool management system (TOMS) is proposed. The integration of technological databases and tool management systems is urgently necessary. The target function for the OPTIS programme, worked out by the programme package Microsoft Visual Basic, is selection of optimal cutting conditions from commercial databases with respect to the lowest costs of machining by taking into account the technological limitations of the metal removal process. The newly developed OPTIS programme selects optimal cutting conditions with respect to the tool maker, workpiece material, type of machining, cutting machine, smallest and greatest cutting conditions, tool, data on series, type of clamping and workpiece geometry.
Ključne besede: machining processes, tool system, manufacturing systems, technological information systems, databases, tool management, machining systems, cutting conditions
Objavljeno: 01.06.2012; Ogledov: 1105; Prenosov: 58
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Relational database as a cogitative part of an intelligent manufacturing system
Igor Drstvenšek, Mirko Ficko, Jože Balič, 2004, izvirni znanstveni članek

Opis: An intelligent manufacturing system is intended to produce one or more subjects that it is designed for in an optimal way. This means that it has to find a proper production process to produce the subject in an optimal way. The manufacturing system can be called "intelligent" when it is able to find applicable optimisation criteria upon its past experiences thus improving its performance in future. Therefore, an intelligent manufacturing system needs capabilities to store data and make decisions upon them. Such a "brain" can be established by a proper design of a technological database and its database management system (DBMS). Examining all constitutive parameters of a work operation a model of a production process organization can be made, which can serve as a basis for a suitable database design. In addition, an application programme that will check the existence and availability of work operations in the database has to be added to the DBMS. What remains are some optimisation criteria upon which we will choose an operation among suitable and available work operations. This task is fulfilled by a genetic algorithm optimisation technique that would consider work operations' data as parameters of optimisation and on this basis search the optimal one out of the set of available operation.
Ključne besede: production processes, optimisation, relational database, database management systems, production automation, manufacturing system
Objavljeno: 01.06.2012; Ogledov: 1089; Prenosov: 61
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