949 resultados para optimization, heuristic, solver, operations, research
Resumo:
VVALOSADE is a research project of professor Anita Lukka's VALORE research team in the Lappeenranta University of Technology. The VALOSADE includes the ELO technology program of Tekes. SMILE is one of four subprojects of the VALOSADE. The SMILE study focuses on the case of the company network that is composed of small and micro-sized mechanical maintenance service providers and forest industry as large-scale customers. The basic principle of the SMILE study is the communication and ebusiness in supply and demand networks. The aim of the study is to develop ebusiness strategy, ebusiness model and e-processes among the SME local service providers, and onthe other hand, between the local service provider network and the forest industry customers in a maintenance and operations service business. A literature review, interviews and benchmarking are used as research methods in this qualitative case study. The first SMILE report, 'Ebusiness between Global Company and Its Local SME Supplier Network', concentrated on creating background for the SMILE study by studying general trends of ebusiness in supply chains and networks of different industries. This second phase of the study concentrates on case network background, such as business relationships, information systems and business objectives; core processes in maintenance and operations service network; development needs in communication among the network participants; and ICT solutions to respond needs in changing environment. In the theory part of the report, different ebusiness models and frameworks are introduced. Those models and frameworks are compared to empirical case data. From that analysis of the empirical data, therecommendations for the development of the network information system are derived. In process industry such as the forest industry, it is crucial to achieve a high level of operational efficiency and reliability, which sets up great requirements for maintenance and operations. Therefore, partnerships or strategic alliances are needed between the network participants. In partnerships and alliances, deep communication is important, and therefore the information systems in the network also are critical. Communication, coordination and collaboration will increase in the case network in the future, because network resources must be optimised to improve competitive capability of the forest industry customers and theefficiency of their service providers. At present, ebusiness systems are not usual in this maintenance network. A network information system among the forest industry customers and their local service providers actually is the only genuinenetwork information system in this total network. However, the utilisation of that system has been quite insignificant. The current system does not add value enough either to the customers or to the local service providers. At present, thenetwork information system is the infomediary that share static information forthe network partners. The network information system should be the transaction intermediary, which integrates internal processes of the network companies; the network information system, which provides common standardised processes for thelocal service providers; and the infomediary, which share static and dynamic information on right time, on right partner, on right costs, on right format and on right quality. This study provides recommendations how to develop this system in the future to add value to the network companies. Ebusiness scenarios, vision, objectives, strategies, application architecture, ebusiness model, core processes and development strategy must be considered when the network information system will be developed in the next development step. The core processes in the case network are demand/capacity management, customer/supplier relationship management, service delivery management, knowledge management and cash flow management. Most benefits from ebusiness solutions come from the electrifying of operational level processes, such as service delivery management and cash flow management.
Resumo:
Small centrifugal compressors are more and more widely used in many industrialsystems because of their higher efficiency and better off-design performance comparing to piston and scroll compressors as while as higher work coefficient perstage than in axial compressors. Higher efficiency is always the aim of the designer of compressors. In the present work, the influence of four partsof a small centrifugal compressor that compresses heavy molecular weight real gas has been investigated in order to achieve higher efficiency. Two parts concern the impeller: tip clearance and the circumferential position of the splitter blade. The other two parts concern the diffuser: the pinch shape and vane shape. Computational fluid dynamics is applied in this study. The Reynolds averaged Navier-Stokes flow solver Finflo is used. The quasi-steady approach is utilized. Chien's k-e turbulence model is used to model the turbulence. A new practical real gas model is presented in this study. The real gas model is easily generated, accuracy controllable and fairly fast. The numerical results and measurements show good agreement. The influence of tip clearance on the performance of a small compressor is obvious. The pressure ratio and efficiency are decreased as the size of tip clearance is increased, while the total enthalpy rise keeps almost constant. The decrement of the pressure ratio and efficiency is larger at higher mass flow rates and smaller at lower mass flow rates. The flow angles at the inlet and outlet of the impeller are increased as the size of tip clearance is increased. The results of the detailed flow field show that leakingflow is the main reason for the performance drop. The secondary flow region becomes larger as the size of tip clearance is increased and the area of the main flow is compressed. The flow uniformity is then decreased. A detailed study shows that the leaking flow rate is higher near the exit of the impeller than that near the inlet of the impeller. Based on this phenomenon, a new partiallyshrouded impeller is used. The impeller is shrouded near the exit of the impeller. The results show that the flow field near the exit of the impeller is greatly changed by the partially shrouded impeller, and better performance is achievedthan with the unshrouded impeller. The loading distribution on the impeller blade and the flow fields in the impeller is changed by moving the splitter of the impeller in circumferential direction. Moving the splitter slightly to the suction side of the long blade can improve the performance of the compressor. The total enthalpy rise is reduced if only the leading edge of the splitter ismoved to the suction side of the long blade. The performance of the compressor is decreased if the blade is bended from the radius direction at the leading edge of the splitter. The total pressure rise and the enthalpy rise of thecompressor are increased if pinch is used at the diffuser inlet. Among the fivedifferent pinch shape configurations, at design and lower mass flow rates the efficiency of a straight line pinch is the highest, while at higher mass flow rate, the efficiency of a concave pinch is the highest. The sharp corner of the pinch is the main reason for the decrease of efficiency and should be avoided. The variation of the flow angles entering the diffuser in spanwise direction is decreased if pinch is applied. A three-dimensional low solidity twisted vaned diffuser is designed to match the flow angles entering the diffuser. The numerical results show that the pressure recovery in the twisted diffuser is higher than in a conventional low solidity vaned diffuser, which also leads to higher efficiency of the twisted diffuser. Investigation of the detailed flow fields shows that the separation at lower mass flow rate in the twisted diffuser is later than in the conventional low solidity vaned diffuser, which leads to a possible wider flow range of the twisted diffuser.
Resumo:
Optimization models in metabolic engineering and systems biology focus typically on optimizing a unique criterion, usually the synthesis rate of a metabolite of interest or the rate of growth. Connectivity and non-linear regulatory effects, however, make it necessary to consider multiple objectives in order to identify useful strategies that balance out different metabolic issues. This is a fundamental aspect, as optimization of maximum yield in a given condition may involve unrealistic values in other key processes. Due to the difficulties associated with detailed non-linear models, analysis using stoichiometric descriptions and linear optimization methods have become rather popular in systems biology. However, despite being useful, these approaches fail in capturing the intrinsic nonlinear nature of the underlying metabolic systems and the regulatory signals involved. Targeting more complex biological systems requires the application of global optimization methods to non-linear representations. In this work we address the multi-objective global optimization of metabolic networks that are described by a special class of models based on the power-law formalism: the generalized mass action (GMA) representation. Our goal is to develop global optimization methods capable of efficiently dealing with several biological criteria simultaneously. In order to overcome the numerical difficulties of dealing with multiple criteria in the optimization, we propose a heuristic approach based on the epsilon constraint method that reduces the computational burden of generating a set of Pareto optimal alternatives, each achieving a unique combination of objectives values. To facilitate the post-optimal analysis of these solutions and narrow down their number prior to being tested in the laboratory, we explore the use of Pareto filters that identify the preferred subset of enzymatic profiles. We demonstrate the usefulness of our approach by means of a case study that optimizes the ethanol production in the fermentation of Saccharomyces cerevisiae.
Resumo:
We present a new branch and bound algorithm for weighted Max-SAT, called Lazy which incorporates original data structures and inference rules, as well as a lower bound of better quality. We provide experimental evidence that our solver is very competitive and outperforms some of the best performing Max-SAT and weighted Max-SAT solvers on a wide range of instances.
Resumo:
Tutkimuksen tavoitteena on arvioida ja analysoida yliopistojen ja yritysten välistä yhteistyötä tutkimus- ja kehitystoiminnassa. Teoriapohjan ja kohdeyrityksen case esimerkin avulla on tarkoitus selvittää kriittiset tekijät yhteistyössä sekä rakentaa tulosten perusteella viitekehys näiden kahden osapuolen yhteistyön onnistumiseksi. Teoriatausta käsittelee osapuolten tärkeimpiä strategioita yhteistyön kannalta, yhteistyön yleisiä ominaisuuksia, vuorovaikutussuhteita niin ympäristöön, toimintoihin kuin osapuoliinkin. Teoriaosuus tukee empiiristä tutkimusta, jossa perehdytään yhteen kansalliseen 3G projektiin Soneran ja Jyväskylän yliopiston välillä. Yrityksen ja yliopiston välinen yhteistyö on hyvin yleistä Suomessa. Motivoivia tekijöitä ovat muun muassa Tekesin kannustava rahoitus ja yhteistyön edullisuus, osapuolten keskittyminen omaan ydinosaamiseensa, tiedon tuotteistuksen ja uusien teorioiden luomisen mahdollisuus, positiiviset vaikutukset markkina-arvoon, imagolliset tekijät sekä varautuminen tulevaisuuden trendeihin.
Resumo:
Työn tavoitteena oli määrittää myyntikonfiguraattorissa käytettävän tuotemallin yleinen rakenne. Ensin selvitettiin tuotemallin luomista ja konseptin suunnittelua kirjallisuuden ja asiantuntijoiden haastattelujen avulla. Asiantuntijoiden haastattelut toteutettiin vapaamuotoisesti kysymyslistaa apuna käyttäen. Tämän lisäksi työssä pohditaan sähköisen liiketoiminnan roolia sekä myyntikonfiguraattorin tulevaisuuden näkymiä. Diplomityössä käsitellään tuotemallia yleisellä tasolla. Toinen näkökulma käsittelee tuotemallia tietoteknisissä sovelluksissa käytettyjen menetelmien pohjalta. Tuotemallin muodostaminen aloitettiin asiakkaalle näkyvästä osasta eli myyntikonfiguraattorin ulkoasusta. Seuraava ongelma oli standardoida tuotetta ja tarjousta kuvaavat dokumentit globaalisti. Tähän ratkaisuun päädyttiin haastattelujen sekä asiantuntijoiden kokoontumisien pohjalta. Loppuosa diplomityöstä käsittelee myyntikonfiguraattorin asemaa kohdeyrityksen sähköisessä liiketoiminnassa sekä esittelee erään näkemyksen myyntikonfiguraattorin yhteenliittymästä asiakashallinta- ja tuotetiedonhallinta järjestelmiin. Diplomityössä saavutettiin asetetut tavoiteet: Myyntikonfigurattori yhtenäistää kohdeyrityksen hinnoittelua globaalisti, nopeuttaa tarjouksentekoprosessia, helpottaa uuden tuotteen lanseerausta ja standardoi tuotemallin globaalisti. Myyntikonfiguraattorin integrointi muihin tietojärjestelmiin tehostaa myynnin toimintoja. Haasteeksi jää loppukäyttäjien kannustaminen tehokkaaseen käyttöön sekä ylläpidon toteuttaminen. Ilman käyttäjiä ja heidän innostustaan voi projekti menettää johdon luottamuksen.
Resumo:
Työn päätarkoitus oli tuottaa Stora Enson käyttöön tietoa kirjakustantajista, yhdestä yrityksen asiakassegmentistä. Yritys oli kiinnostunut useista asioista, jotka koskivat asiakkaita ja heidän mielipiteitään. Tarkoitus on, että Stora Enso voi käyttää tutkimuksella koottua tietoa oman toimintansa suunnittelun tukena. Kerätty sekundääritieto esittelee eurooppalaisen kirjakustantamisen nykytilaa ja tulevaisuutta sekä teorioita, jotka tukevat tutkittuja aihealueita. Primääritieto kerättiin henkilökohtaisilla haastatteluilla. Otanta koostui kymmenestä kirjakustantajasta, jotka toimivat Suomessa sekä Stora Enson päämarkkina-alueilla. Tutkimus tarjoaa päivitetyn kuvauksen kirjakustantamisesta. Haastateltavien mielipiteet alan trendeistä olivat yhteneviä yleisen mielipiteen kanssa, eikä suuria mielipide-eroavaisuuksia havaittu. Kustantajien toimintatapoja ja päätöksentekoprosesseja voidaan kuvata monimutkaisiksi, koska useat asiat vaikuttavat kirjan syntyyn ja paperin ostoprosessiin. Lisäksi tutkimus esittelee haastateltavien mielipiteitä paperin merkityksestä heidän liiketoiminnassaan.
Resumo:
Designing new teaching programs for both undergraduate and graduate university studies involves integrating concepts and methodologies regarding quality, work safety and hazard prevention, and environmental protection. One of the challenges facing Spanish research within the realm of European Higher Education concerns health and safety issues in the Arts.In the case of Fine Arts, student exploration is one of the fundamental pillars of the study program; therefore it is imperative that art studios be optimized. This optimization affects both designated resources (infrastructures, materials, equipment, etc.) and organization of the teaching force.In this context, the aim of our research is to improve educational practices by designing quality measures that are both friendly to the environment and hazardous free. The aim here is to assure adequate art studio and laboratory management, and provide students with hazard free health and environmentally safe concepts that can be incorporated in their professional lives.The school of Fine Arts at the University of Barcelona is part of a pilot program, where our experience in educational innovation and research is serving as a reference for the implantation of OSHAS 18001 norms.
Resumo:
Designing new teaching programs for both undergraduate and graduate university studies involves integrating concepts and methodologies regarding quality, work safety and hazard prevention, and environmental protection. One of the challenges facing Spanish research within the realm of European Higher Education concerns health and safety issues in the Arts.In the case of Fine Arts, student exploration is one of the fundamental pillars of the study program; therefore it is imperative that art studios be optimized. This optimization affects both designated resources (infrastructures, materials, equipment, etc.) and organization of the teaching force.In this context, the aim of our research is to improve educational practices by designing quality measures that are both friendly to the environment and hazardous free. The aim here is to assure adequate art studio and laboratory management, and provide students with hazard free health and environmentally safe concepts that can be incorporated in their professional lives.The school of Fine Arts at the University of Barcelona is part of a pilot program, where our experience in educational innovation and research is serving as a reference for the implantation of OSHAS 18001 norms.
Resumo:
Designing new teaching programs for both undergraduate and graduate university studies involves integrating concepts and methodologies regarding quality, work safety and hazard prevention, and environmental protection. One of the challenges facing Spanish research within the realm of European Higher Education concerns health and safety issues in the Arts.In the case of Fine Arts, student exploration is one of the fundamental pillars of the study program; therefore it is imperative that art studios be optimized. This optimization affects both designated resources (infrastructures, materials, equipment, etc.) and organization of the teaching force.In this context, the aim of our research is to improve educational practices by designing quality measures that are both friendly to the environment and hazardous free. The aim here is to assure adequate art studio and laboratory management, and provide students with hazard free health and environmentally safe concepts that can be incorporated in their professional lives.The school of Fine Arts at the University of Barcelona is part of a pilot program, where our experience in educational innovation and research is serving as a reference for the implantation of OSHAS 18001 norms.
Resumo:
The threats caused by global warming motivate different stake holders to deal with and control them. This Master's thesis focuses on analyzing carbon trade permits in optimization framework. The studied model determines optimal emission and uncertainty levels which minimize the total cost. Research questions are formulated and answered by using different optimization tools. The model is developed and calibrated by using available consistent data in the area of carbon emission technology and control. Data and some basic modeling assumptions were extracted from reports and existing literatures. The data collected from the countries in the Kyoto treaty are used to estimate the cost functions. Theory and methods of constrained optimization are briefly presented. A two-level optimization problem (individual and between the parties) is analyzed by using several optimization methods. The combined cost optimization between the parties leads into multivariate model and calls for advanced techniques. Lagrangian, Sequential Quadratic Programming and Differential Evolution (DE) algorithm are referred to. The role of inherent measurement uncertainty in the monitoring of emissions is discussed. We briefly investigate an approach where emission uncertainty would be described in stochastic framework. MATLAB software has been used to provide visualizations including the relationship between decision variables and objective function values. Interpretations in the context of carbon trading were briefly presented. Suggestions for future work are given in stochastic modeling, emission trading and coupled analysis of energy prices and carbon permits.
Resumo:
Metaheuristic methods have become increasingly popular approaches in solving global optimization problems. From a practical viewpoint, it is often desirable to perform multimodal optimization which, enables the search of more than one optimal solution to the task at hand. Population-based metaheuristic methods offer a natural basis for multimodal optimization. The topic has received increasing interest especially in the evolutionary computation community. Several niching approaches have been suggested to allow multimodal optimization using evolutionary algorithms. Most global optimization approaches, including metaheuristics, contain global and local search phases. The requirement to locate several optima sets additional requirements for the design of algorithms to be effective in both respects in the context of multimodal optimization. In this thesis, several different multimodal optimization algorithms are studied in regard to how their implementation in the global and local search phases affect their performance in different problems. The study concentrates especially on variations of the Differential Evolution algorithm and their capabilities in multimodal optimization. To separate the global and local search search phases, three multimodal optimization algorithms are proposed, two of which hybridize the Differential Evolution with a local search method. As the theoretical background behind the operation of metaheuristics is not generally thoroughly understood, the research relies heavily on experimental studies in finding out the properties of different approaches. To achieve reliable experimental information, the experimental environment must be carefully chosen to contain appropriate and adequately varying problems. The available selection of multimodal test problems is, however, rather limited, and no general framework exists. As a part of this thesis, such a framework for generating tunable test functions for evaluating different methods of multimodal optimization experimentally is provided and used for testing the algorithms. The results demonstrate that an efficient local phase is essential for creating efficient multimodal optimization algorithms. Adding a suitable global phase has the potential to boost the performance significantly, but the weak local phase may invalidate the advantages gained from the global phase.
Resumo:
The goal of the Master’s thesis is to develop and to analyze the optimization method for finding a geometry shape of classical horizontal wind turbine blades based on set of criteria. The thesis develops a technique that allows the designer to determine the weight of such factors as power coefficient, sound pressure level and the cost function in the overall process of blade shape optimization. The optimization technique applies the Desirability function. It was never used before in that kind of technical problems, and in this sense it can claim to originality of research. To do the analysis and the optimization processes more convenient the software application was developed.
Resumo:
This thesis studies the use of heuristic algorithms in a number of combinatorial problems that occur in various resource constrained environments. Such problems occur, for example, in manufacturing, where a restricted number of resources (tools, machines, feeder slots) are needed to perform some operations. Many of these problems turn out to be computationally intractable, and heuristic algorithms are used to provide efficient, yet sub-optimal solutions. The main goal of the present study is to build upon existing methods to create new heuristics that provide improved solutions for some of these problems. All of these problems occur in practice, and one of the motivations of our study was the request for improvements from industrial sources. We approach three different resource constrained problems. The first is the tool switching and loading problem, and occurs especially in the assembly of printed circuit boards. This problem has to be solved when an efficient, yet small primary storage is used to access resources (tools) from a less efficient (but unlimited) secondary storage area. We study various forms of the problem and provide improved heuristics for its solution. Second, the nozzle assignment problem is concerned with selecting a suitable set of vacuum nozzles for the arms of a robotic assembly machine. It turns out that this is a specialized formulation of the MINMAX resource allocation formulation of the apportionment problem and it can be solved efficiently and optimally. We construct an exact algorithm specialized for the nozzle selection and provide a proof of its optimality. Third, the problem of feeder assignment and component tape construction occurs when electronic components are inserted and certain component types cause tape movement delays that can significantly impact the efficiency of printed circuit board assembly. Here, careful selection of component slots in the feeder improves the tape movement speed. We provide a formal proof that this problem is of the same complexity as the turnpike problem (a well studied geometric optimization problem), and provide a heuristic algorithm for this problem.
Resumo:
Many research works have being carried out on analyzing grain storage facility costs; however a few of them had taken into account the analysis of factors associated to all pre-processing and storage steps. The objective of this work was to develop a decision support system for determining the grain storage facility costs and utilization fees in grain storage facilities. The data of a CONAB storage facility located in Ponta Grossa - PR, Brazil, was used as input of the system developed to analyze its specific characteristics, such as amount of product received and stored throughout the year, hourly capacity of drying, cleaning, and receiving, and dispatch. By applying the decision support system, it was observed that the reception and expedition costs were exponentially reduced as the turnover rate of the storage increased. The cleaning and drying costs increased linearly with grain initial moisture. The storage cost increased exponentially as the occupancy rate of the storage facility decreased.