Assessing self-organization and emergence in Evolvable Assembly Systems (EAS)

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores

A design and implementation methodology for high variety electronics assembly systems

Small indigenous manufacturers of electronic equipment are coming under increasingly severe pressure to adopt a strong defensive position against large multinational and Far Eastern companies. A common response to this threat has been for these firms to adopt a 'market driven' business strategy based on quality and customer service, rather than a 'technology led' strategy which uses technical specification and price to compete. To successfully implement this type of strategy there is a need for production systems to be redesigned to suit the new demands of marketing. Increased range and fast response require economy of scope rather t ban economy or scale while the organisation's culture must promote quality and process consciousness. This paper describes the 'Modular Assembly Cascade' concept which addresses these needs by applying the principles of flexible manufacturing (FMS) and just in time (,JlT) to electronics assembly. A methodology for executing the concept is also outlined. This is called DRAMA (Design Houtirw !'or· Adopting Modular Assembly).

Modular system design and control for flexible assembly

Flexible Assembly Systems (FASs) are normally associated with the automatic, or robotic, assembly of products, supported by automated material handling systems. However, manual assembly operations are still prevalent within many industries, where the complexity and variety of products prohibit the development of suitable automated assembly equipment. This article presents a generic model for incorporating flexibility into the design and control of assembly operations concerned with high variety/low volume manufacture, drawing on the principles for Flexible Manufacturing Systems (FMS) and Just-in-Time (JIT) delivery. It is based on work being undertaken in an electronics company where the assembly operations have been overhauled and restructured in response to a need for greater flexibility, shorter cycle times and reduced inventory levels. The principles employed are in themselves not original. However, the way they have been combined and tailored has created a total manufacturing control system which represents a new concept for responding to demands placed on market driven firms operating in an uncertain environment.

Intelligent System for Computer Aided Assembly Process Planning

This paper presents the concepts of the intelligent system for aiding of the module assembly technology. The first part of this paper presents a project of intelligent support system for computer aided assembly process planning. The second part includes a coincidence description of the chosen aspects of implementation of this intelligent system using technologies of artificial intelligence (artificial neural networks, fuzzy logic, expert systems and genetic algorithms).

The Production Scheduling in Assembly System with Evolutionary Algorithm

In this paper an evolutionary algorithm is proposed for solving the problem of production scheduling in assembly system. The aim of the paper is to investigate a possibility of the application of evolutionary algorithms in the assembly system of a normally functioning enterprise producing household appliances to make the production graphic schedule.

Review of the application of flexible, measurement-assisted assembly technology in aircraft manufacturing

Aircraft assembly is the most important part of aircraft manufacturing. A large number of assembly fixtures must be used to ensure the assembly accuracy in the aircraft assembly process. Traditional fixed assembly fixture could not satisfy the change of the aircraft types, so the digital flexible assembly fixture was developed and was gradually applied in the aircraft assembly. Digital flexible assembly technology has also become one of the research directions in the field of aircraft manufacturing. The aircraft flexible assembly can be divided into three assembly stages that include component-level flexible assembly, large component-level flexible assembly, and large components alignment and joining. This article introduces the architecture of flexible assembly systems and the principles of three types of flexible assembly fixtures. The key technologies of the digital flexible assembly are also discussed. The digital metrology system provides the basis for the accurate digital flexible assembly. Aircraft flexible assembly systems mainly use laser tracking metrology systems and indoor Global Positioning System metrology systems. With the development of flexible assembly technology, the digital flexible assembly system will be widely used in current aircraft manufacturing.

Collaborative environment to support a professional community

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores

An agent-based evolutionary approach for manufacturing system layout design

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores

Lightweight robust behavior industrial agent methodology

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores

Geänderte Zielsetzungen bei der Konfiguration und dem Betrieb von Fließmontagesystemen und deren Berücksichtigung in der Fachliteratur

Ursprünglich zielte die Gestaltung von Montagesystemen in Form von Fließsystemen auf eine gleichmäßig hohe Stückzahl eines einzelnen Produkts bei hohem Automatisierungsgrad ab. Aus Gründen wie z.B. ständig zunehmende Anforderungen durch Kundenwünsche oder Absatzveränderungen sind die Montageprozesse fortwährend an die veränderten Rahmenbedingungen anzupassen. In diesem Zusammenhang gewinnen Gesichtspunkte wie Flexibilität, höhere Verfügbarkeit bzw. Nutzungsgrade, Energieeffizienz und Wirtschaftlichkeit stärker an Bedeutung. Die Konfiguration und Planung von Fließmontagesystemen erfolgt i.d.R. durch die Zerlegung der gesamten Planungsprobleme in kleine Teilprobleme, die durch unterschiedliche Planungsmaßnahmen bzw. systematische Planungs-schritte lösbar sind. Mit den vorstehenden Hinweisen ist außerdem nur ein Teil der Gesichtspunkte aufgeführt, die aus heutiger Sicht zu geänderten (ergänzten) Zielsetzungen führen. Der Beitrag wird diese Veränderungen durch Darstellung eines sinnvollen zielführenden Katalogs von Zielsetzungen und dessen Abgleich mit der Fachliteratur nachvollziehbar machen.

Process Selection Using Variation and Cost Relations

Variations are inherent in all manufacturing processes and can significantly affect the quality of a final assembly, particularly in multistage assembly systems. Existing research in variation management has primarily focused on incorporating GD&T factors into variation propagation models in order to predict product quality and allocate tolerances. However, process induced variation, which has a key influence on process planning, has not been fully studied. Furthermore, the link between variation and cost has not been well established, in particular the effect that assembly process selection has on the final quality and cost of a product. To overcome these barriers, this paper proposes a novel method utilizing process capabilities to establish the relationship between variation and cost. The methodology is discussed using a real industrial case study. The benefits include determining the optimum configuration of an assembly system and facilitating rapid introduction of novel assembly techniques to achieve a competitive edge.

Leistungsorientierte Bewertung und Auswahl von Materialbereitstellungsstrategien mittels Fuzzy Axiomatic Design

Eine effiziente Gestaltung von Materialbereitstellungsprozessen ist eine entscheidende Voraussetzung für die Sicherstellung einer hohen Verfügbarkeit von Materialien in der Montage. Die Auswahl adäquater Bereitstellungsstrategien muss sich stets an den Anforderungen des Materialbereitstellungsprozesses orientieren. Die Leistungsanforderungen an eine effektive Materialbereitstellung werden maßgeblich durch den Montageprozess determiniert. Diesen Leistungsanforderungen ist eine passgenaue Materialbereitstellungsstrategie gegenüberzustellen. Die Formulierung der Leistungsanforderungen kann dabei in qualitativer oder quantitativer Form erfolgen. Allein die Berücksichtigung quantitativer Daten ist unzureichend, denn häufig liegen zum Zeitpunkt der Planung weder belastbare quantitative Daten vor, noch erscheint der Aufwand zu deren Ermittlung angemessen. Zudem weisen die herkömmlichen Methoden, die im Rahmen der Auswahl von Materialbereitstellungsstrategien häufig eingesetzt werden, den Nachteil auf, dass eine Nichterfüllung einer bestimmten Leistungsanforderung durch eine besonders gute Erfüllung einer anderen Leistungsanforderung kompensiert werden kann (Zeit vs. Qualität). Um die Auswahl einer Materialbereitstellungsstrategie unter Berücksichtigung qualitativer und quantitativer Anforderungen durchführen zu können, eignet sich in besonderer Weise die Methode des Fuzzy Axiomatic Designs. Diese Methode erlaubt einen Abgleich von Anforderungen an den Materialbereitstellungsprozess und der Eignung unterschiedlicher Materialbereitstellungsstrategien.

Simulation als Methode zur Konzipierung vernetzter, getakteter Montagesysteme für variantenreiche Produkte

Die Montage von Produkten in getakteten Fließstraßen als Alternative zu ortsfesten Varianten führt in der Regel zur Verbesserung der logistischen Zielerfüllung. Das volle Potential dieser Organisationsart wird jedoch weitgehend nur für standardisierte Produkte mit hohen Stückzahlen erschlossen. Hindernisse zur Produktion variantenreicher Großerzeugnisse mit volatilen Arbeitsinhalten in einer Fließstraße bestehen vor allem in der Beherrschung der Komplexität in Bezug auf dazu erforderliche flexible Arbeitszeitmodelle, optimierte Produktreihenfolgen sowie operative Taktzeitvariationen. Sollen mehrere Fließstraßen mit differenzierten Produktionsparametern gekoppelt werden, steigt der Anspruch noch einmal erheblich. Bei der Konzipierung und Erprobung geeigneter Organisationsmodelle auf Basis diverser Produktionsszenarien kann auf den Einsatz der Simulationstechnik nicht verzichtet werden.

Methods for construction and analysis of computational models in systems biology : applications to the modelling of the heat shock response and the self-assembly of intermediate filaments

Systems biology is a new, emerging and rapidly developing, multidisciplinary research field that aims to study biochemical and biological systems from a holistic perspective, with the goal of providing a comprehensive, system- level understanding of cellular behaviour. In this way, it addresses one of the greatest challenges faced by contemporary biology, which is to compre- hend the function of complex biological systems. Systems biology combines various methods that originate from scientific disciplines such as molecu- lar biology, chemistry, engineering sciences, mathematics, computer science and systems theory. Systems biology, unlike “traditional” biology, focuses on high-level concepts such as: network, component, robustness, efficiency, control, regulation, hierarchical design, synchronization, concurrency, and many others. The very terminology of systems biology is “foreign” to “tra- ditional” biology, marks its drastic shift in the research paradigm and it indicates close linkage of systems biology to computer science. One of the basic tools utilized in systems biology is the mathematical modelling of life processes tightly linked to experimental practice. The stud- ies contained in this thesis revolve around a number of challenges commonly encountered in the computational modelling in systems biology. The re- search comprises of the development and application of a broad range of methods originating in the fields of computer science and mathematics for construction and analysis of computational models in systems biology. In particular, the performed research is setup in the context of two biolog- ical phenomena chosen as modelling case studies: 1) the eukaryotic heat shock response and 2) the in vitro self-assembly of intermediate filaments, one of the main constituents of the cytoskeleton. The range of presented approaches spans from heuristic, through numerical and statistical to ana- lytical methods applied in the effort to formally describe and analyse the two biological processes. We notice however, that although applied to cer- tain case studies, the presented methods are not limited to them and can be utilized in the analysis of other biological mechanisms as well as com- plex systems in general. The full range of developed and applied modelling techniques as well as model analysis methodologies constitutes a rich mod- elling framework. Moreover, the presentation of the developed methods, their application to the two case studies and the discussions concerning their potentials and limitations point to the difficulties and challenges one encounters in computational modelling of biological systems. The problems of model identifiability, model comparison, model refinement, model inte- gration and extension, choice of the proper modelling framework and level of abstraction, or the choice of the proper scope of the model run through this thesis.

Computational models for and from biology : simple gene assembly and reaction systems

The advancement of science and technology makes it clear that no single perspective is any longer sufficient to describe the true nature of any phenomenon. That is why the interdisciplinary research is gaining more attention overtime. An excellent example of this type of research is natural computing which stands on the borderline between biology and computer science. The contribution of research done in natural computing is twofold: on one hand, it sheds light into how nature works and how it processes information and, on the other hand, it provides some guidelines on how to design bio-inspired technologies. The first direction in this thesis focuses on a nature-inspired process called gene assembly in ciliates. The second one studies reaction systems, as a modeling framework with its rationale built upon the biochemical interactions happening within a cell. The process of gene assembly in ciliates has attracted a lot of attention as a research topic in the past 15 years. Two main modelling frameworks have been initially proposed in the end of 1990s to capture ciliates’ gene assembly process, namely the intermolecular model and the intramolecular model. They were followed by other model proposals such as templatebased assembly and DNA rearrangement pathways recombination models. In this thesis we are interested in a variation of the intramolecular model called simple gene assembly model, which focuses on the simplest possible folds in the assembly process. We propose a new framework called directed overlap-inclusion (DOI) graphs to overcome the limitations that previously introduced models faced in capturing all the combinatorial details of the simple gene assembly process. We investigate a number of combinatorial properties of these graphs, including a necessary property in terms of forbidden induced subgraphs. We also introduce DOI graph-based rewriting rules that capture all the operations of the simple gene assembly model and prove that they are equivalent to the string-based formalization of the model. Reaction systems (RS) is another nature-inspired modeling framework that is studied in this thesis. Reaction systems’ rationale is based upon two main regulation mechanisms, facilitation and inhibition, which control the interactions between biochemical reactions. Reaction systems is a complementary modeling framework to traditional quantitative frameworks, focusing on explicit cause-effect relationships between reactions. The explicit formulation of facilitation and inhibition mechanisms behind reactions, as well as the focus on interactions between reactions (rather than dynamics of concentrations) makes their applicability potentially wide and useful beyond biological case studies. In this thesis, we construct a reaction system model corresponding to the heat shock response mechanism based on a novel concept of dominance graph that captures the competition on resources in the ODE model. We also introduce for RS various concepts inspired by biology, e.g., mass conservation, steady state, periodicity, etc., to do model checking of the reaction systems based models. We prove that the complexity of the decision problems related to these properties varies from P to NP- and coNP-complete to PSPACE-complete. We further focus on the mass conservation relation in an RS and introduce the conservation dependency graph to capture the relation between the species and also propose an algorithm to list the conserved sets of a given reaction system.