Master of Engineering (Research) / The overall objective of this research was to realise the practical application of Hierarchical Asynchronous Parallel Evolutionary Algorithms for Multi-objective and Multidisciplinary Design Optimisation (MDO) of UAV Systems using high fidelity analysis tools. The research looked at the assumed aerodynamics and structures of two production UAV wings and attempted to optimise these wings in isolation to the rest of the vehicle. The project was sponsored by the Asian Office of the Air Force Office of Scientific Research under contract number AOARD-044078. The two vehicles wings which were optimised were based upon assumptions made on the Northrop Grumman Global Hawk (GH), a High Altitude Long Endurance (HALE) vehicle, and the General Atomics Altair (Altair), Medium Altitude Long Endurance (MALE) vehicle. The optimisations for both vehicles were performed at cruise altitude with MTOW minus 5% fuel and a 2.5g load case. The GH was assumed to use NASA LRN 1015 aerofoil at the root, crank and tip locations with five spars and ten ribs. The Altair was assumed to use the NACA4415 aerofoil at all three locations with two internal spars and ten ribs. Both models used a parabolic variation of spar, rib and wing skin thickness as a function of span, and in the case of the wing skin thickness, also chord. The work was carried out by integrating the current University of Sydney designed Evolutionary Optimiser (HAPMOEA) with Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) tools. The variable values computed by HAPMOEA were subjected to structural and aerodynamic analysis. The aerodynamic analysis computed the pressure loads using a Boeing developed Morino class panel method code named PANAIR. These aerodynamic results were coupled to a FEA code, MSC.Nastran® and the strain and displacement of the wings computed. The fitness of each wing was computed from the outputs of each program. In total, 48 design variables were defined to describe both the structural and aerodynamic properties of the wings subject to several constraints. These variables allowed for the alteration of the three aerofoil sections describing the root, crank and tip sections. They also described the internal structure of the wings allowing for variable flexibility within the wing box structure. These design variables were manipulated by the optimiser such that two fitness functions were minimised. The fitness functions were the overall mass of the simulated wing box structure and the inverse of the lift to drag ratio. Furthermore, six penalty functions were added to further penalise genetically inferior wings and force the optimiser to not pass on their genetic material. The results indicate that given the initial assumptions made on all the aerodynamic and structural properties of the HALE and MALE wings, a reduction in mass and drag is possible through the use of the HAPMOEA code. The code was terminated after 300 evaluations of each hierarchical level due to plateau effects. These evolutionary optimisation results could be further refined through a gradient based optimiser if required. Even though a reduced number of evaluations were performed, weight and drag reductions of between 10 and 20 percent were easy to achieve and indicate that the wings of both vehicles can be optimised.

Master of Engineering (Research) / The overall objective of this research was to realise the practical application of Hierarchical Asynchronous Parallel Evolutionary Algorithms for Multi-objective and Multidisciplinary Design Optimisation (MDO) of UAV Systems using high fidelity analysis tools. The research looked at the assumed aerodynamics and structures of two production UAV wings and attempted to optimise these wings in isolation to the rest of the vehicle. The project was sponsored by the Asian Office of the Air Force Office of Scientific Research under contract number AOARD-044078. The two vehicles wings which were optimised were based upon assumptions made on the Northrop Grumman Global Hawk (GH), a High Altitude Long Endurance (HALE) vehicle, and the General Atomics Altair (Altair), Medium Altitude Long Endurance (MALE) vehicle. The optimisations for both vehicles were performed at cruise altitude with MTOW minus 5% fuel and a 2.5g load case. The GH was assumed to use NASA LRN 1015 aerofoil at the root, crank and tip locations with five spars and ten ribs. The Altair was assumed to use the NACA4415 aerofoil at all three locations with two internal spars and ten ribs. Both models used a parabolic variation of spar, rib and wing skin thickness as a function of span, and in the case of the wing skin thickness, also chord. The work was carried out by integrating the current University of Sydney designed Evolutionary Optimiser (HAPMOEA) with Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) tools. The variable values computed by HAPMOEA were subjected to structural and aerodynamic analysis. The aerodynamic analysis computed the pressure loads using a Boeing developed Morino class panel method code named PANAIR. These aerodynamic results were coupled to a FEA code, MSC.Nastran® and the strain and displacement of the wings computed. The fitness of each wing was computed from the outputs of each program. In total, 48 design variables were defined to describe both the structural and aerodynamic properties of the wings subject to several constraints. These variables allowed for the alteration of the three aerofoil sections describing the root, crank and tip sections. They also described the internal structure of the wings allowing for variable flexibility within the wing box structure. These design variables were manipulated by the optimiser such that two fitness functions were minimised. The fitness functions were the overall mass of the simulated wing box structure and the inverse of the lift to drag ratio. Furthermore, six penalty functions were added to further penalise genetically inferior wings and force the optimiser to not pass on their genetic material. The results indicate that given the initial assumptions made on all the aerodynamic and structural properties of the HALE and MALE wings, a reduction in mass and drag is possible through the use of the HAPMOEA code. The code was terminated after 300 evaluations of each hierarchical level due to plateau effects. These evolutionary optimisation results could be further refined through a gradient based optimiser if required. Even though a reduced number of evaluations were performed, weight and drag reductions of between 10 and 20 percent were easy to achieve and indicate that the wings of both vehicles can be optimised.

During the design and development stages of mechanical structures, after each modification made in order to satisfy design criteria, dynamic characteristics of the structure change and should be determined through reanalyzing the structure dynamically. Due to the significance of computational time and cost in design processes, it is inevitable for structural modification methods, especially for large systems, to become involved in predicting the dynamic behavior of modified structures from those of the original and modifying structures. Since most engineering structures are inherently nonlinear, linear approach may not be valid no more. Therefore, conventional structural modification methods can not be directly used, instead a nonlinear structural modification method needs to be employed. In this thesis, it is aimed to adapt an effective linear structural modification method to structures with nonlinear modification or coupling. The amplitude dependencies of nonlinearities are modeled by using describing function method. Mathematical formulations are embedded in a computer program developed in MATLAB&reg / with a graphical user interface. The software uses modal analysis results of ANSYS&reg / for the original structure and dynamic stiffness matrix and nonlinearity information that belong to the modifying structure in order to calculate dynamic response of the modified structure. The approach is verified by applying it to both discrete and real test structures previously studied in literature and generated discrete structures, then comparing the results with prior ones and ones obtained via time domain integration, respectively. Several other case studies are also included in order to demonstrate the applicability and to investigate the performance of the method. It is concluded in this study that the structural modification method proposed can be successfully and efficiently used for structures with nonlinear modification or coupling.

Background: A key idea of feature orientation is to decompose a software product line along the features it provides. Feature decomposition is orthogonal to object-oriented decomposition it crosscuts the underlying package and class structure. It has been argued often that feature decomposition improves system structure (reduced coupling, increased cohesion). However, recent empirical findings suggest that this is not necessarily the case, which is the motivation for our empirical investigation. Aim: In fact, there is little empirical evidence on how the alternative decompositions of feature orientation and object orientation compare to each other in terms of their association with observable properties of system structure (coupling, cohesion). This motivated us to empirically investigate and compare the properties of three decompositions (object-oriented, feature-oriented, and their intersection) of 28 feature-oriented software product lines. Method: In an exploratory, observational study, we quantify internal attributes, such as import coupling and cohesion, to describe and analyze the different decompositions of a feature-oriented product line in a systematic, reproducible, and comparable manner. For this purpose, we use three established software measures (CBU, IUD, EUD) as well as standard distribution statistics (e.g., Gini coefficient). Results: First, feature decomposition is associated with higher levels of structural coupling in a product line than a decomposition into classes. Second, although coupling is concentrated in feature decompositions, there are not necessarily hot-spot features. Third, the cohesion of feature modules is not necessarily higher than class cohesion, whereas feature modules serve more dependencies internally than classes. Fourth, coupling and cohesion measurement show potential for sampling optimization in complex static and dynamic product-line analyses (product-line type checking, feature-interaction detection). Conclusions: Our empirical study raises critical questions about alleged advantages of feature decomposition. At the same time, we demonstrate how the measurement of structural attributes can facilitate static and dynamic analyses of software product lines. (authors' abstract) / Series: Technical Reports / Institute for Information Systems and New Media

A presente pesquisa, eminentemente bibliográfica, visa apresentar e analisar alguns dos conceitos fundamentais da teoria dos sistemas sociais de Niklas Luhmann, que propõe um novo paradigma no campo da Sociologia e tenta superar as teorias sociais clássicas. Sistemas sociais, na acepção luhmanniana, são sistemas autopoiéticos, fechados operacionalmente e auto-referentes, formados a partir de uma diferenciação com o ambiente externo. Essa diferenciação ocorre com o estabelecimento de uma marca, que possibilita ao sistema estabelecer o que lhe pertence e o que não lhe pertence. Sistemas sociais operam a partir de processos comunicativos, que adquirem sentido a partir da rede recursiva interna, cujo acesso ao ambiente é fechado. O ambiente é formado pelos outros sistemas existentes e por informações desorganizadas. São apresentados os conceitos fundamentais da teoria para possibilitar a discussão de um aspecto específico: as relações inter-sistêmicas, principalmente por meio dos acoplamentos estruturais, mecanismo pelo qual um sistema utiliza, para colocar em funcionamento seus próprios elementos, as estruturas de um outro sistema, sem com isso, no entanto, confundir os limites entre eles. São relações inter-sistêmicas duradouras. Finalmente, temporalidade, racionalidade e limites da observação dos sistemas sociais são aspectos utilizados para a elaboração e apresentação de um conceito ainda inédito, o de processo sobrecomunicativo. O conceito visa explicar como podem ocorrer eventos de influência externa em sistemas autopoiéticos sem o abandono das premissas da teoria, como o fechamento operacional e a auto-referência. A estrutura formal da dissertação consiste em uma análise do funcionamento dos conceitos da teoria, observando a integração entre eles dentro do desenho geral, além de reflexões acerca de aspectos específicos dos conceitos que tratam da manutenção da integridade dos sistemas e de seu relacionamento com o ambiente e com os outros sistemas e da discussão do novo conceito apresentado, com a estruturação de seu funcionamento e a exemplificação de alguns de seus aspectos. Além disso, o trabalho contém também a tradução de um capítulo de um livro de Luhmann, que trata especificamente do conceito de acoplamento estrutural, para possibilitar o contato direto com o texto luhmanniano. / This thesis - based on bibliographic research - presents and analyzes some of the fundamental concepts of the Niklas Luhmann’s social systems theory, which proposes a new paradigm for the Sociology and intends to surpass the classic social theories. Social systems, in the luhmannian sense, are autopoietic, operatively closed and self-referred systems, emerged from a differentiation from the environment. This differentiation occurs with the establishment of a mark, which permits the system to recognize what pertains or not to the system. Social systems operate with communications that acquire meaning through the inside recursive net, which access is closed to the environment. The environment is formed by other existing systems and by disorganized information. The fundamental concepts of the theory are presented in order to introduce the debate about an specific aspect: the inter-systemic relationship, specially through structural coupling, the mechanism by which a system operates its own elements through the use of the structures of another system, meantime the limits between them are maintained. Structural couplings are long lasting inter-systemic relationships. Finally, the temporality, rationality and limits of the observation of the social systems are used for the proposition of a new concept: overcommunication. The concept intends to explain how external influences can occur in autopoietic systems without the abandonment of the premises of the theory, such as the operational closure and the self-reference. The formal structure of the thesis is as follows: an analysis of the functioning of the concepts of the theory, taking in account their integration into the general draw; reflections on specific aspects of the concepts which deal with the preservation of the integrity of the system and on the relationship of the system with the environment and with other systems and, finally, the presentation of the new concept, its structure, functioning and examples. A translation into Portuguese of a Luhmann’s text about structural coupling is attached.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-03-28T13:03:44Z No. of bitstreams: 1 Arnaldo Rizzardo Filho_.pdf: 1553627 bytes, checksum: e44533b4558f254bda6d0ae4a140bcc2 (MD5) / Made available in DSpace on 2018-03-28T13:03:44Z (GMT). No. of bitstreams: 1 Arnaldo Rizzardo Filho_.pdf: 1553627 bytes, checksum: e44533b4558f254bda6d0ae4a140bcc2 (MD5) Previous issue date: 2017-10-19 / Nenhuma / A sociedade e sua economia evoluem com relações organizadas em formato de rede. Redes empresariais são eventos econômicos que se afirmam no último quartel do século passado. São eventos pós-modernos. O interesse envolvido nas relações econômicas em rede continua sendo a diminuição dos riscos e custos em uma economia que se torna cada vez mais competitiva e onerada. As redes se tratam de soluções econômicas que orbitam um largo campo de ação entre os contratos de intercâmbio e de sociedade. Suas causas são múltiplas, com revoluções (revolução digital) e crises (crise do Estado Social) compondo sua base fática. Dentro desse panorama contextual, o tema será apresentado a partir da relação entre o direito e as redes empresariais. As redes empresariais serão caracterizadas econômica, administrativa, sociológica e jurídicamente. Materialmente, as redes possuem estruturas diversificadas, objetivos próprios, estratégias racionais, formatos variados, relação interna diferenciada, dentre tantas outras especificidades que serão adequadamente tratadas. Institutos clássicos das relações econômicas, como individualismo e competição (díade), passam a ceder espaço para novos aspectos de cunho coletivo, cooperativo e coordenado (tríade). A questão se torna complexa porque envolve o relacionamento entre dois subsistemas sociais autopoiéticos, com códigos e programas próprios, que se fecham constituindo suas próprias complexidades, e se reproduzem a partir de suas relações internas recursivas. Para ocorrer o relacionamento entre dois sistemas autopoiéticos, é preciso um elemento acoplador, que ao mesmo tempo possui significado interno para cada um dos sistemas acoplados, e irrita o outro sistema a ponto de fazê-lo evoluir. Esse elemento acoplador é aqui entendido como coordenação das redes empresariais. Em termos organizacionais, significa governança e gestão de relações econômicas cooperadas; juridicamente, significa obrigação contratual. Na praxis jurídica (operação jurídica), o direito não compreende as redes como diferenciados subsistemas econômicos (coletivos e cooperativos e coordenados). O sistema jurídico, quando se relaciona com os sistemas das redes empresariais, o faz a partir de sentidos vinculados ao sistema econômico geral (individualista e competitivo), resultando, ao fim e ao cabo, um direito incongruente, segundo as bases luhmannianas. / Society and the economy have been developing through relationships in a network format. Business networks are new economic events that emerge from the last quarter of the last century, in a globalization movement of great breath because of the digital revolution. Within this contextual panorama, the relationship between law and business networks will be addressed. Business networks will be considered economic, administrative, sociological and legal events, with their own objectives and strategies, varied formats, differentiated complexity and legal rationality. Classical institutes of economic relations, such as individualism and competition, begin to give way to a new, collective, cooperative and coordinated relationship. The issue becomes complex because it involves the relationship between the legal system and the corporate network systems. Theoretically, networks and law are autopoietic systems, with their own codes and programs, which close themselves up as their own complexity, and reproduce themselves from their recursive internal relations. In order to occur the relationship between two autopoietic systems, it is necessary a coupling element, which at the same time has internal meaning for each of the coupled systems, irritates the other system to the point of making it evolve. This coupling element is understood here as governance, management, coordination of corporate networks, which for them means organization of cooperative collective relations, and for the legal system means imputation, duty, responsibility. In practice, this rationality does not take place. In truth, law does not recognize networks as differentiated economic subsystems. Law, when called to temporalize behavioral expectations related to the networks, it does so from the meanings linked to the general economic environment, resulting in an incongruous law after the Luhmannian bases.

Submitted by Maicon Juliano Schmidt (maicons) on 2015-06-12T16:44:14Z No. of bitstreams: 1 Daniela da Graça Stieh_.pdf: 4005373 bytes, checksum: 3af02a50a61c6e56510b78eb8facbde9 (MD5) / Made available in DSpace on 2015-06-12T16:44:14Z (GMT). No. of bitstreams: 1 Daniela da Graça Stieh_.pdf: 4005373 bytes, checksum: 3af02a50a61c6e56510b78eb8facbde9 (MD5) Previous issue date: 2015-02-27 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / PROEX - Programa de Excelência Acadêmica / Essa dissertação de mestrado consiste no estudo do percurso das interações de professores no contexto de uma Escola Estadual de Ensino Fundamental localizada no município de Sapucaia do Sul/RS e que tem participado de programas de inclusão digital. Os sujeitos da pesquisa foram professores que atuam na escola desde o momento em que as tecnologias digitais passaram a fazer parte do cotidiano da escola, mais especificamente, desde que a escola passou a participar de programa de inclusão digital na modalidade 1:1 – um computador por aluno e professor. O dinamismo das interações nesse contexto e seus percursos foram investigados a partir da passagem e da convivência entre mídias analógicas e digitais, identificadas nessa pesquisa como: pré-digital e digital. A metodologia de pesquisa utilizada foi a cartográfica, o que me possibilitou a saída da condição de observadora para participante, juntamente com os professores, na investigação de pistas dos percursos das interações. Como aporte teórico, a pesquisa foi fundamentada a partir dos autores Maturana e Varela justamente para fazer a relação dos acoplamentos estruturais de terceira ordem e o caminho biológico de todos os processos de interação. Esses autores me possibilitaram um olhar de como a escola e os professores se relacionam com o dinamismo das trocas. O momento pré-digital, na visão do professor, é compreendido como uma sobreposição do momento digital. A pesquisa transformou a realidade dos professores com relação às interações a partir das reflexões e da atenção aos espaços da escola tanto no digital quanto no pré-digital. A partir de oficina e cartografia dos percursos das interações na escola com os professores é que surgiram os resultados deste estudo. Para tanto, foram utilizados dois critérios para que os resultados da pesquisa fossem percebidos: as interações que se transformaram frente ao digital e as que se conservaram no pré-digital. A partir desses dois critérios é que foi percebido que alguns percursos cartografados pelos professores tanto no pré-digital quanto no digital não se caracterizam como processos vitais, pois eles não atribuem uma continuidade no compartilhamento de ideias e trocas entre eles. / This master thesis is the study of interactions of teachers in the context of a public School Elementary School located in the municipality of Sapucaia do Sul/RS and has participated in programs of digital inclusion. The research subjects were teachers working at the school since the moment in which the digital technologies have become part of the daily life of the school, more specifically, since the school joined the program of digital inclusion in modality 1:1 - a computer per student and teacher. The research methodology used was the cartographic, which made it possible for me to exit the condition of an observer to participant, along with the teachers, the research of slopes of pathways of interactions. As the theoretical, the search was justified from the authors Maturana and Varela precisely in order to make the relationship of structural couplings of third order and the biological path of all processes of interaction. These authors has allowed me a glimpse of how the school and the teachers relate to the dynamism of trade. The time pre-digital, from the point of view of the teacher, is understood as an overlay to the digital time. The research has transformed the reality of teachers with respect to the interactions from the reflections and the attention to spaces of the school both in digital and in pre-digital. From workshop and mapping of pathways of interactions at the school with the teachers is that there are the results of this study. For both, two criteria were used to ensure that the results of the research were perceived: the interactions that become front to digital and those preserved in the pre-digital. From these two criteria is that it was realized that some routes mapped by teachers both in the pre-digital and the digital not characterised as vital processes, because they do not give a continuity on the sharing of ideas and trade between them.

A presente pesquisa, eminentemente bibliográfica, visa apresentar e analisar alguns dos conceitos fundamentais da teoria dos sistemas sociais de Niklas Luhmann, que propõe um novo paradigma no campo da Sociologia e tenta superar as teorias sociais clássicas. Sistemas sociais, na acepção luhmanniana, são sistemas autopoiéticos, fechados operacionalmente e auto-referentes, formados a partir de uma diferenciação com o ambiente externo. Essa diferenciação ocorre com o estabelecimento de uma marca, que possibilita ao sistema estabelecer o que lhe pertence e o que não lhe pertence. Sistemas sociais operam a partir de processos comunicativos, que adquirem sentido a partir da rede recursiva interna, cujo acesso ao ambiente é fechado. O ambiente é formado pelos outros sistemas existentes e por informações desorganizadas. São apresentados os conceitos fundamentais da teoria para possibilitar a discussão de um aspecto específico: as relações inter-sistêmicas, principalmente por meio dos acoplamentos estruturais, mecanismo pelo qual um sistema utiliza, para colocar em funcionamento seus próprios elementos, as estruturas de um outro sistema, sem com isso, no entanto, confundir os limites entre eles. São relações inter-sistêmicas duradouras. Finalmente, temporalidade, racionalidade e limites da observação dos sistemas sociais são aspectos utilizados para a elaboração e apresentação de um conceito ainda inédito, o de processo sobrecomunicativo. O conceito visa explicar como podem ocorrer eventos de influência externa em sistemas autopoiéticos sem o abandono das premissas da teoria, como o fechamento operacional e a auto-referência. A estrutura formal da dissertação consiste em uma análise do funcionamento dos conceitos da teoria, observando a integração entre eles dentro do desenho geral, além de reflexões acerca de aspectos específicos dos conceitos que tratam da manutenção da integridade dos sistemas e de seu relacionamento com o ambiente e com os outros sistemas e da discussão do novo conceito apresentado, com a estruturação de seu funcionamento e a exemplificação de alguns de seus aspectos. Além disso, o trabalho contém também a tradução de um capítulo de um livro de Luhmann, que trata especificamente do conceito de acoplamento estrutural, para possibilitar o contato direto com o texto luhmanniano. / This thesis - based on bibliographic research - presents and analyzes some of the fundamental concepts of the Niklas Luhmann’s social systems theory, which proposes a new paradigm for the Sociology and intends to surpass the classic social theories. Social systems, in the luhmannian sense, are autopoietic, operatively closed and self-referred systems, emerged from a differentiation from the environment. This differentiation occurs with the establishment of a mark, which permits the system to recognize what pertains or not to the system. Social systems operate with communications that acquire meaning through the inside recursive net, which access is closed to the environment. The environment is formed by other existing systems and by disorganized information. The fundamental concepts of the theory are presented in order to introduce the debate about an specific aspect: the inter-systemic relationship, specially through structural coupling, the mechanism by which a system operates its own elements through the use of the structures of another system, meantime the limits between them are maintained. Structural couplings are long lasting inter-systemic relationships. Finally, the temporality, rationality and limits of the observation of the social systems are used for the proposition of a new concept: overcommunication. The concept intends to explain how external influences can occur in autopoietic systems without the abandonment of the premises of the theory, such as the operational closure and the self-reference. The formal structure of the thesis is as follows: an analysis of the functioning of the concepts of the theory, taking in account their integration into the general draw; reflections on specific aspects of the concepts which deal with the preservation of the integrity of the system and on the relationship of the system with the environment and with other systems and, finally, the presentation of the new concept, its structure, functioning and examples. A translation into Portuguese of a Luhmann’s text about structural coupling is attached.

Background: A key idea of feature orientation is to decompose a software product line along the features it provides. Feature decomposition is orthogonal to object-oriented decomposition it crosscuts the underlying package and class structure. It has been argued often that feature decomposition improves system structure (reduced coupling, increased cohesion). However, recent empirical findings suggest that this is not necessarily the case, which is the motivation for our empirical investigation. Aim: In fact, there is little empirical evidence on how the alternative decompositions of feature orientation and object orientation compare to each other in terms of their association with observable properties of system structure (coupling, cohesion). This motivated us to empirically investigate and compare the properties of three decompositions (object-oriented, feature-oriented, and their intersection) of 28 feature-oriented software product lines. Method: In an exploratory, observational study, we quantify internal attributes, such as import coupling and cohesion, to describe and analyze the different decompositions of a feature-oriented product line in a systematic, reproducible, and comparable manner. For this purpose, we use three established software measures (CBU, IUD, EUD) as well as standard distribution statistics (e.g., Gini coefficient). Results: First, feature decomposition is associated with higher levels of structural coupling in a product line than a decomposition into classes. Second, although coupling is concentrated in feature decompositions, there are not necessarily hot-spot features. Third, the cohesion of feature modules is not necessarily higher than class cohesion, whereas feature modules serve more dependencies internally than classes. Fourth, coupling and cohesion measurement show potential for sampling optimization in complex static and dynamic product-line analyses (product-line type checking, feature-interaction detection). Conclusions: Our empirical study raises critical questions about alleged advantages of feature decomposition. At the same time, we demonstrate how the measurement of structural attributes can facilitate static and dynamic analyses of software product lines. (authors' abstract) / Series: Technical Reports / Institute for Information Systems and New Media

Background: A key idea of feature orientation is to decompose a software product line along the features it provides. Feature decomposition is orthogonal to object-oriented decomposition it crosscuts the underlying package and class structure. It has been argued often that feature decomposition improves system structure (reduced coupling, increased cohesion). However, recent empirical findings suggest that this is not necessarily the case, which is the motivation for our empirical investigation. Aim: In fact, there is little empirical evidence on how the alternative decompositions of feature orientation and object orientation compare to each other in terms of their association with observable properties of system structure (coupling, cohesion). This motivated us to empirically investigate and compare the properties of three decompositions (object-oriented, feature-oriented, and their intersection) of 28 feature-oriented software product lines. Method: In an exploratory, observational study, we quantify internal attributes, such as import coupling and cohesion, to describe and analyze the different decompositions of a feature-oriented product line in a systematic, reproducible, and comparable manner. For this purpose, we use three established software measures (CBU, IUD, EUD) as well as standard distribution statistics (e.g., Gini coefficient). Results: First, feature decomposition is associated with higher levels of structural coupling in a product line than a decomposition into classes. Second, although coupling is concentrated in feature decompositions, there are not necessarily hot-spot features. Third, the cohesion of feature modules is not necessarily higher than class cohesion, whereas feature modules serve more dependencies internally than classes. Fourth, coupling and cohesion measurement show potential for sampling optimization in complex static and dynamic product-line analyses (product-line type checking, feature-interaction detection). Conclusions: Our empirical study raises critical questions about alleged advantages of feature decomposition. At the same time, we demonstrate how the measurement of structural attributes can facilitate static and dynamic analyses of software product lines. (authors' abstract) / Series: Technical Reports / Institute for Information Systems and New Media