Uma abordagem de otimização multiobjetivo para projeto arquitetural de linha de produto de software

Resumo: A indústria de software tem adotado a abordagem de Linha de Produto de Software (LPS) com o objetivo de aumentar o reúso de software e diminuir o tempo de produção e os custos de desenvolvimento dos produtos. Nessa abordagem, o principal artefato e a arquitetura de LPS (PLA - Product Line Architecture). No entanto, obter uma PLA modular, extensível e reusável e uma tarefa não trivial. O arquiteto pode se apoiar em métricas arquiteturais para definir e melhorar o projeto da PLA. Contudo, essa tarefa pode envolver vários fatores, muitas vezes conflitantes entre si, e encontrar o melhor trade-off entre as métricas utilizadas para avaliar o projeto transforma o projeto de PLA em uma tarefa que demanda grande esforço humano. Nesse contexto, o projeto de PLA pode ser formulado como um problema de otimização com varios fatores. Porém, elaborar um projeto que atenda a todos os fatores envolvidos pode ser mais difícil do que reconhecer um bom projeto. Problemas da Engenharia de Software similares a esse tem sido eficientemente resolvidos com algoritmos de busca em um campo de pesquisa conhecido como Engenharia de Software Baseada em Busca (SBSE - Search Based Software Engineering). Entretanto, as abordagens existentes utilizadas para otimizar arquiteturas de software nãao são apropriadas para projeto de PLAs, pois não consideram características específicas de LPS. Desse modo, este trabalho propõe uma abordagem de otimização multiobjetivo automatizada para avaliar e melhorar um projeto de PLA no que tange a modularização de características, estabilidade do projeto e extensibilidade de LPS. A abordagem proposta inclui: (a) um processo sistemático para conduzir a otimização de projeto de PLA por meio de algoritmos de busca; (b) um metamodelo que permite que esses algoritmos manipulem projetos de PLA; (c) novos operadores de busca para evoluir projetos de PLA em termos de modularização de características; e (d) um tratamento multiobjetivo para o problema de projeto de PLA. Esse tratamento multiobjetivo engloba métricas que indicam a modularização de características e a extensibilidade de LPS, além de métricas convencionais para medir princípios básicos de projeto como coesão e acoplamento. Ao final do processo de otimização, um conjunto de possíveis soluções de projeto de PLA que representam os melhores trade-off entre os objetivos otimizados e retornado. O arquiteto deve selecionar uma solução de acordo com as suas prioridades. A ferramenta OPLA-Tool foi desenvolvida para instanciar a abordagem usando algoritmos evolutivos multiobjetivos, os quais tem sido usados com sucesso na área de SBSE. Utilizando a OPLA-Tool, quatro estudos empíricos foram realizados com nove PLAs para avaliar: os operadores de busca propostos; o uso das métricas de LPS; e os algoritmos escolhidos. Em comparação às PLAs originais, os resultados mostraram que a abordagem proposta consegue gerar projetos mais estáveis, mais elegantes e com melhor modularização de características

Physical layer aware open optical networking

L'abstract è presente nell'allegato / the abstract is in the attachmen

Multiple software product lines to configure applications of internet of things

Software product lines (SPL) emulate the industrial production lines that are capable of generating large volumes of products through reuse schemes and mass production. A multi product line (MPL) aims to reuse of several SPL. Feature models are often used to manage the existing resources of SPLs and define valid products through notations and relationships such as mandatory, optional, and alternative features. The main contribution of this study is a method to manage the variability of multiple SPL and generate a new portfolio of products for Internet of Things (IoT). For this, the problem of developing a universal feature model (FM) for an MPL from merging the FMs of the individual SPLs with a Search-Based Software Engineering (SBSE) technique is addressed. In addition, the authors propose a multi-objective optimisation model to maximise the reusability and compatibility between features and minimise the development cost. The model facilitates the design of an MPL-feature model. Authors' empirical results show that the proposed model solved by genetic algorithms allows to configure a variety of software products and to determine the scope of the MPL

NASA Tech Briefs, August 1992

Topics include: Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

Socio–Technical Software Engineering: a Quality–Architecture–Process Perspective

This dissertation provides a model, which focuses on Quality, Architecture, and Process aspects, to manage software development lifecycles in a sustainable way. Here, with sustainability is meant a context-aware approach to IT, which considers all relevant socio-technical units of analysis. Both social (e.g., at the level of the stakeholders community, organization, team, individual) and technical (e.g., technological environments coding standards, language) dimensions play a key role to develop IT systems which respond to contingent needs and may implement future requirements in a flexible manner. We used different research methods and analyzed the problem from several perspectives, in a pragmatic way, to deliver useful insights both to the research and practitioners communities. The Software Quality, Architecture, and Process (SQuAP) model, highlights the key critical factors to develop systems in a sustainable ways. The model was firstly induced and then deduced from a longitudinal research of the financial sector. To support the model, SQuAP-ont, an OWL ontology was develop as a managerial and assessment tool. A real-world case study within a mission-critical environment shows how these dimensions are critical for the development of IT applications. Relevant IT managers concerns were also covered with reference to software reuse and contracting problems. Finally, a long-term contribution for the educational community presents actionable teaching styles and models to train future professionals to act in a Cooperative Thinking fashion

Manufacture and characterisation of bioresorbable fibre reinforced composite rods and screws for bone fracture fixation applications

Bioresorbable implants are an attractive alternative to metallic bone fixation devices and offer potential to eliminate some of the clinical challenges with the latter. This work explores the manufacturing of fully bioresorbable fibre-reinforced composite rods and screws for such applications. Poly lactic acid (PLA) and phosphate glass fibres (PGF) were combined to provide mechanical reinforcement and biocompatibility characteristics. Aligned and randomly reinforced PLA/PGF composites were prepared by compression moulding prior to thermomechanical deformation into rod and screw forms. In vitro degradation and mechanical properties retention were investigated in phosphate buffered saline (PBS) at 37°C. The composite rods and screws exceeded published data for bioresorbable implants in their virgin state and were towards the upper range of cortical bone properties. The properties reduced rapidly in an aqueous medium and this was attributed to matrix plasticisation and fibre/matrix disbonding. The degraded samples maintained strength and stiffness close to the lower limits of the cortical bone. Water uptake and mass loss for composites exceeded equivalent values for PLA alone due to water wicking at the fibre/matrix interface. Ion release tests correlated linearly with mass loss profiles confirming that the dominant degradation mechanism was fibre dissolution. The PLA/PGF composites also exhibited good biocompatibility to human osteosarcoma and human mesenchymal stem cells

Probing the Mechanics of Protein Materials with Molecular Dynamics Simulations

Mechanische Kraft ist eine wichtige Form des biomechanischen Signals. Ihre Rolle und Wirkung jedoch sind noch unerforscht und der Mechanismus der meisten Kraftsensoren wirft Rätsel auf. Wie widerstehen Biomoleküle wie Proteine hohen mechanischen Kräften? Wie können sie so empfindlich auf eine Änderung der mechanischen Umgebung reagieren? Antworten auf diese Fragen würden neue Türen für die Herstellung von Biomaterialien öffnen. Seide ist ein natürliches Protein. Es erscheint uns als geheimnisvolles Material, ist es doch all seinen industriell hergestellten Pendants mechanisch überlegen. Die Kombination von extrem steifen mit enorm elastischen Untereinheiten führt zu einer ungewöhnlich hohen Zähigkeit, die zu umfangreichen Forschungsaufwand auf dem Gebiet der Seidenmechanik inspiriert. In dieser Arbeit wurde die Mechanik von Seidenproteinen mithilfe von Multiskalen-Modelierung untersucht. Hierzu wurden molekulardynamische Simulationen, die alle Atome betrachten sowie Finite-Elemente-Methoden verwendet. Durch die Kombination dieser beiden Methoden konnten wir einerseits eine hohe Genauigkeit des Modells erhalten, und andererseits das modellierte System trotz des hohen Rechenaufwands ebenso auf der Mikrometerskala betrachten. Mit diesem hybriden Ansatz liefern wir heute den Vorschlag für eine seidene Faserstruktur, die stärker ist, als was uns die Natur liefern kann: Eine serielle Anordnung der steifen kristallinen Untereinheiten in einer weichen, amorphen Peptid-Matrix ist der gemeinhin angenommen zufälligen Anordnung, die als die natürliche gilt, Überlegen. Protein beta-Faltblatt-Kristalle mit kleiner Querschnittsfläche und erhöhter beta-Strang Länge stärken die Faserstruktur. Wir gehen davon aus, dass diese Erkenntnis ebenso auf ähnliche semi-kristalline Materialien wie Polyamide zutrifft. Vorläufige Studien zu dieser Fragestellung wurden im Rahmen dieser Arbeit durchgeführt. Auch für Muskeln spielt Kraft eine entscheidende Rolle. Muskel Protein-Fibrillen bilden Netzwerke, welche die mechanische Belastung in lebenden Zellen tragen. Das komplexe Netzwerk aus Muskelproteinen besteht aus Molekülen, die für ihre mechanische Adaptivität magermaßgeschneiderten sind. Das M-Band Protein Myomesin ist eine solche Proteinfaser. In Zusammenarbeit mit Experimentalisten, die uns mit Röntgenstrukturanalysen und Daten aus ihrer Kraft-Spektroskopie unterstützten, untersuchten wir, wie Myomesin in molekular-dynamischen Simulationen auf Krafteinwirkungen reagiert. Myomesin besteht aus langen alpha-Helices die zwischen starren Domänen lokalisiert sind. Unsere Analysen zeigen, dass diese als Stamm-Absorber im Muskelkontraktionszyklus fungieren. Des weiteren enthält Myomesin eine Kraft resistente Dimerisierungs-Schnittstelle. Diese erhält die Stabilität des Fibrillen-Netzwerks im M-Band der Kraft generierenden Einheit im Muskel. Der Fokus dieser Arbeit liegt auf zwei biologischen Systemen: Seide und Myomesin. Ziel war, deren mechanische Funktion zu verstehen. Mit Hilfe mo-dernster Techniken wie molekular-dynamischen Simulationen, Kraftvertei-lungsanalyse und Finite Elemente Methoden konnten wir zeigen, dass die Natur diese beiden Proteine in Hinsicht auf ihre mechanischen Eigenschaften optimiert hat. Diese beiden Proteine teilen ihr Aufbauschema: Beide Struk-turen werden vom beta-Faltblatt dominiert, das sich entlang der Zugrichtung ausrichtet, um seine mechanische Stabilität zu erreichen. Unser theore-tischer Ansatz bildet einen Grundstein für weitere Untersuchungen, die die Rolle von Kraft in Biosystemen analysieren. Er kann als Leitlinie für neue Experimente auf diese und ähnliche Protein-Systeme dienen. Wie wir für Seidenfasern zeigen konnten, lässt sich der rechnerische Ansatz bei er Gestaltung natürlicher oder künstlicher nanostrukturierter Materialien utzen