The literature review on emerging concepts of 'Business model' and 'Business model innovation' finds significant theoretical and practical potential to facilitate the strategising and innovating activities of modern organisations operating in complex and dynamic business environments. However, a further review of extant literature reveals that although a significant knowledge-base has been accumulated focusing on the content and process aspects of the phenomenon, very few of the conducted studies take a practice-based perspective. Therefore, in keeping with the broader research question of current strategising practices, this research investigates the issue from many possible philosophical, theoretical and methodological angles, in turn making several contributions to the theory and practice of business models while also opening up several potential future research avenues. This research consists of four main research stages sequentially covering problem formulation, two theory creation phases and problem solving, thereby meeting the requirements of a practice-based management research through relevance rather than merely rigour, as in conventional scientific research. As a result, it offers several research contributions to both the theory and practice of business models, which can be immediately put into practice by theorists, practitioners and entrepreneurs: a pluralistic business model research classification framework; a dynamic practice-based approach to the construction of business models; a knowledge-based conceptualisation of business models and a dynamic capability matrix for business model practices. Additionally, this research also offers potential future contributions to adjacent research streams such as dynamic capabilities, strategy as practice and research methodology. Overall, by utilising the philosophy of pragmatism, this thesis advances the contemporary discipline of business models towards a practice-based science, crucially and timely bridging the knowledge gap in existing practice-based theories and frameworks business models. It is hopes that this work will gave rise to a new movement of research on business models, positioning itself as a well established applied-oriented management science among the broader disciplines of strategy, innovation and entrepreneurship.

O transporte aéreo e a indústria de sistemas de defesa foram setores pioneiros na utilização de sistemas computacionais críticos, incrementando os níveis de automação nas atividades de controle do espaço aéreo. Com o crescimento desses setores, verificado pela expansão dos números de vôos, volumes de cargas e usuários, assim como pela ampliação e diversidade das operações militares, os sistemas de controle têm assumido maior complexidade técnica, introduzindo novos recursos de automação ou facilidades adicionais de apoio para funções exercidas manualmente. Essa situação tem ampliado a dependência dos serviços prestados, relativamente à disponibilidade dos sistemas computacionais. Diretrizes de projeto e procedimentos operacionais são estabelecidos para manter os níveis de segurança nos casos de falha, no entanto a disponibilidade torna-se parâmetro crítico, na medida em que algumas falhas podem afetar a eficiência nominal da prestação dos serviços. Nesse cenário, este trabalho propõe um modelo para avaliação da disponibilidade de sistemas de controle do espaço aéreo, a partir de recursos de análises da teoria de filas. Inicialmente é citado um modelo geral para análise de disponibilidade de data centers. Em seguida, é apresentada uma extensão do modelo geral para análise da disponibilidade em sistemas de controle do espaço aéreo. Para isso, considerou-se a intervenção humana existente nessa atividade, cujas decisões de controle são exercidas por operadores qualificados (controladores), tanto nas atividades inerentes ao serviço de controle, quanto nos casos de degradação, nos quais os operadores ou técnicos de manutenção assumem alguma tarefa de reparo, decorrente da eventual indisponibilidade de funções do sistema. / Due to the growth in airspace utilization, which can be verified both in terms of the expansions in aerial movements, airports and volumes of transported passengers and cargo, as well as in terms of the expansion of military operations demands and diversity, airspace control activities have been increasing their technical complexity, introducing new features into the existent automation systems or creating additional resources for the automation of some functions previously performed by human operators. This situation has increased the dependence on the availability of the computer systems involved in the services provided by control centers. Project directives and operational procedures are established in order to maintain the safety integrity levels of the systems, in case any failure occurs. However, the availability becomes a critical parameter, once failure events can force an undesirable state of degraded operation, jeopardizing the nominal capacity of the services being performed through any controlled airspace. In this scenario, this work presents an availability model for the computer systems used in airspace control centers, based on analysis from queuing theory. A general model is first presented, referencing a case study that describes the use of queuing models to access the availability of generic data centers. Further considerations are introduced to extend this general model in order to propose its application for the specific computer systems used in airspace control centers, where operational control relies on human activities. In this case, system operation involves intensive use of human-machine interfaces (HMI), for the regular control services provided, and additional technical or operational maintenance activities, occasionally imposed to repair a momentary loss of any function of the system.

Les circuits intégrés ne sont pas à l'abri d'interférences naturelles ou malveillantes qui peuvent provoquer des fautes transitoires conduisant à des erreurs (Soft errors) et potentiellement à un comportement erroné. Ceci doit être maîtrisé surtout dans le cas des systèmes critiques qui imposent des contraintes de sûreté et/ou de sécurité. Pour optimiser les stratégies de protection de tels systèmes, il est fondamental d'identifier les éléments les plus critiques. L'évaluation de la criticité de chaque bloc permet de limiter les protections aux blocs les plus sensibles. Cette thèse a pour objectif de proposer des approches permettant d'analyser, tôt dans le flot de conception, la robustesse d'un système numérique. Le critère clé utilisé est la durée de vie des données stockées dans les registres, pour une application donnée. Dans le cas des systèmes à base de microprocesseur, une approche analytique a été développée et validée autour d'un microprocesseur SparcV8 (LEON3). Celle-ci repose sur une nouvelle méthodologie permettant de raffiner les évaluations de criticité des registres. Ensuite, une approche complémentaire et plus générique a été mise en place pour calculer la criticité des différents points mémoires à partir d'une description synthétisable. L'outil mettant en œuvre cette approche a été éprouvé sur des systèmes significatifs tels que des accélérateurs matériels de chiffrement et un système matériel/logiciel basé sur le processeur LEON3. Des campagnes d'injection de fautes ont permis de valider les deux approches proposées dans cette thèse. En outre, ces approches se caractérisent par leur généralité, leur efficacité en termes de précision et de rapidité, ainsi que leur faible coût de mise en œuvre et leur capacité à ré-exploiter les environnements de validation fonctionnelle. / Integrated circuits are not immune to natural or malicious interferences that may cause transient faults which lead to errors (soft errors) and potentially to wrong behavior. This must be mastered particularly in the case of critical systems which impose safety and/or security constraints. To optimize protection strategies of such systems, it is essential to identify the most critical elements. The assessment of the criticality of each block allows limiting the protection to the most sensitive blocks. This thesis aims at proposing approaches in order to analyze, early in the design flow, the robustness of a digital system. The key criterion used is the lifetime of data stored in the registers for a given application. In the case of microprocessor-based systems, an analytical approach has been developed and validated on a SparcV8 microprocessor (LEON3). This approach is based on a new methodology to refine assessments of registers criticality. Then a more generic and complementary approach was implemented to compute the criticality of all flip-flops from a synthesizable description. The tool implementing this approach was tested on significant systems such as hardware crypto accelerators and a hardware/software system based on the LEON3 processor. Fault injection campaigns have validated the two approaches proposed in this thesis. In addition, these approaches are characterized by their generality, their efficiency in terms of accuracy and speed and a low-cost implementation. Another benefit is also their ability to re-use the functional verification environments.

Les fonctions de commande et de contrôle sont parmi les plus importantes des systèmes embarqués critiques utilisés dans des activités telles les transports, la santé ou la gestion de l’énergie. Leur impact potentiel sur la sûreté de fonctionnement fait de la vérification de leur correction l’un des points les plus critiques de leur développement. Cette vérification est usuellement effectuée en accord avec les normes de certification décrivant un ensemble d’objectifs à atteindre afin d’assurer un haut niveau de qualité du système et donc de prévenir l’apparition de défauts. Cette vérification du logiciel est traditionnellement basée sur de nombreux tests et des activitiés de relectures de code, toutefois les versions les plus récentes des standards de certification permettent l’utilisation de nouvelles approches de développement telles que l’ingénierie dirigée par les modèles et les méthodes formelles ainsi que l’utilisation d’outil pour assister les processus de développement. Les outils de génération automatique de code sont exploités dans la plupart des processus de développement de systèmes embarqués critiques afin d’éviter des erreurs de programmation liées à l’humain et pour assurer le respect des règles de production de code. Ces outils ayant pour vocation de remplacer les humains pour la production de code, des erreurs dans leur conception peuvent causer l’apparition d’erreurs dans le code généré. Il est donc nécessaire de vérifier que le niveau de qualité de l’outil est le même que celui du code produit en s’assurant que les objectifs spécifiées dans les normes de qualification sont couverts. Nos travaux visent à exploiter l’ingénierie dirigée par les modèles et les méthodes formelles pour développer ces outils et ainsi atteindre un niveau de qualité plus élevé que les approches traditionnelles. Les fonctions critiques de commande et de contrôle sont en grande partie conçues à l’aide de langages graphiques à flot de données. Ces langages sont utilisés pour modéliser des systèmes complexes à l’aide de blocs élémentaires groupés dans des librairies de blocs. Un bloc peut être un objet logiciel sophistiqué exposant une haute variabilité tant structurelle que sémantique. Cette variabilité est à la fois liée aux valeurs des paramètres du bloc ainsi qu’à son contexte d’utilisation. Dans notre travail, nous concentrons notre attention en premier lieu sur la spécification formelle de ces blocs ainsi que sur la vérification de ces spécifications. Nous avons évalué plusieurs approches et techniques dans le but d’assurer une spécification formelle, structurellement cohérente, vérifiable et réutilisable des blocs. Nous avons finalement conçu un langage basé sur l’ingénierie dirigées par les modèles dédié à cette tâche. Ce langage s’inspire des approches des lignes de produit logiciel afin d’assurer une gestion de la variabilité des blocs à la fois correcte et assurant un passage à l’échelle. Nous avons appliqué cette approche et la vérification associée sur quelques exemples choisis de blocs issus d’applications industrielles et l’avons validé sur des prototypes logiciels que nous avons développé. Les blocs sont les principaux éléments des langages d’entrée utilisés pour la génération automatique de logiciels de commande et de contrôle. Nous montrons comment les spécifications formelles de blocs peuvent être transformées en des annotations de code afin de simplifier et d’automatiser la vérification du code généré. Les annotations de code sont vérifiées par la suite à l’aide d’outils spécialisés d’analyse statique de code. En utilisant des observateur synchrones pour exprimer des exigences de haut niveau sur les modèles en entrée du générateur, nous montrons comment la spécification formelle de blocs peut être utilisée pour la génération d’annotations de code et par la suite pour la vérification automatique des exigences. / Control and command softwares play a key role in safety-critical embedded systems used for human related activities such as transportation, healthcare or energy. Their impact on safety makes the assessment of their correctness the central point in their development activities. Such systems verification activities are usually conducted according to normative certification guidelines providing objectives to be reached in order to ensure development process reliability and thus prevent flaws. Verification activities usually relies on tests and proof reading of the software but recent versions of certification guidelines are taking into account the deployment of new development paradigms such as model-based development, and formal methods; or the use of tools in assistance of the development processes. Automatic code generators are used in most safety-critical embedded systems development in order to avoid human related software production errors and to ensure the respect of development quality standards. As these tools are supposed to replace humans in the software code production activities, errors in these tools may result in embedded software flaws. It is thus in turn mandatory to ensure the same level of correctness for the tool itself than for the expected produced code. Tools verification shall be done according to qualification guidelines. We advocate in our work the use of model-based development and formal methods for the development of these tools in order to reach a higher quality level. Critical control and command software are mostly designed using graphical dataflow languages. These languages are used to express complex systems relying on atomic operations embedded in blocks that are gathered in block libraries. Blocks may be sophisticated pieces of software with highly variable structure and semantics. This variability is dependent on the values of the block parameters and of the block's context of use. In our work, we focus on the formal specification and verification of such block based languages. We experimented various techniques in order to ensure a formal, sound, verifiable and usable specification for blocks. We developed a domain specific formal model-based language specifically tailored for the specification of structure and semantics of blocks. This specification language is inspired from software product line concepts in order to ensure a correct and scalable management of the blocks variability. We have applied this specification and verification approach on chosen block examples from common industrial use cases and we have validated it on tool prototypes. Blocks are the core elements of the input language of automatic code generators used for control and command systems development. We show how our blocks formal specification can be translated as code annotations in order to ease and automate the generated code verification. Code annotations are verified using specialised static code analysis tools. Relying on synchronous observers to express high level requirements at the input model level, we show how formal block specification can also be used for the translation of high level requirements as verifiable code annotations discharged using the same specialised tooling. We finally target the assistance of code generation tools qualification activities by arguing on the ability to automatically generate qualification data such as requirements, tests or simulation results for the verification and development of automatic code generators from the formal block specification.

Les arguments de sécurité sont couramment utilisés pour montrer que des efforts suffisants ont été faits pour atteindre les objectifs de sécurité. Ainsi, la sécurité du système est souvent justifiée par l'évaluation des arguments de sécurité. L'évaluation de tels arguments repose généralement sur l’avis d’experts sans s’appuyer sur des outils ou des méthodes dédiés. Ceci pose des questions sur la validité des résultats. Dans cette thèse, une approche quantitative est proposée, basé sur la théorie de Dempster-Shafer (théorie D-S) pour évaluer notre confiance dans les arguments de sécurité. Cette approche gère le problème à travers les aspects suivants: 1) Définition formelle de la confiance dans les arguments basée sur la théorie D-S; 2) Développement de règles d'agrégation des paramètres de confiance; 3) Proposition d'un cadre d'évaluation quantitatif des arguments de sécurité. Une application dans le domaine ferroviaire conduit à l'estimation des paramètres du cadre par une enquête auprès d'experts en sécurité. / Safety arguments, also called Safety Cases, are commonly used to present that adequate efforts have been made to achieve the safety goals. Thus, the system safety is often justified through assessing the safety arguments. The assessment of such arguments is usually implemented by experts without any dedicated tool or method. This leads to a questionable validity of the results. In this thesis, a quantitative framework is proposed based on Dempster-Shafer theory (D-S theory) to assess our confidence in Safety Cases. This framework manages the issue in following aspects: 1) Formal definition of confidence in arguments based on D-S theory; 2) Development of confidence aggregation rules; 3) Proposition of a quantitative assessment framework of safety arguments. An application in railway domain realises the parameter estimation of the framework by a survey with safety experts.

At safety-critical, mission-critical and business-critical systems the high cost of failure makes required the use of methods and techniques to ensure application reliability. In this context, formal languages, as Circus or specific languages versions like Safety-Critical Java, were created to facilitate the verification and validation of applications so consequently assisting to increase the overall reliability. Despite of the reliability increase, the modeled systems in formal languages can not be executed subsequently has to be implemented in a traditional programming language. It is in this process of free translation where occur most mistakes that end up not ensuring that the generated code conforms to the specification. Based on that premise, this paper propose to expound a strategy of translation from models written in Circus language to executable programs in SCJ language. Among the main objectives and contributions include the creation of EBNFs of the two languages and the detailed description of the translation of all elements between the two languages. / Em sistemas críticos de segurança, missão ou negócios o alto custo das falhas faz com que sejam necessários o uso de métodos e técnicas para garantir a confiabilidade da aplicação. É neste contexto que foram criadas linguagens formais como o Circus ou versões específicas de linguagens como o Safety-Critical Java para facilitar a verificação e validação das aplicações criadas e aumentar consequentemente a confiabilidade geral da aplicação. Apesar de aumentar a confiabilidade, os sistemas modelados em linguagens formais não podem ser executados e então precisam ser implementados em uma linguagem de programação tradicional. É nesse processo de livre tradução do sistema especificado onde ocorrem a maioria dos erros que acabam por não garantir que o código gerado esteja de acordo com a especificação. Baseando-se nessa premissa o presente trabalho propõem-se a apresentar uma estratégia de tradução de modelos escritos na linguagem Circus para programas executáveis na linguagem SCJ. Entre os principais objetivos e contribuições do trabalho estão a criação das EBNFs das duas linguagens e a descrição detalhada da tradução de todos os elementos entre as duas linguagens.

Made available in DSpace on 2014-12-17T14:55:50Z (GMT). No. of bitstreams: 1 DiogoLR_DISSERT.pdf: 2166475 bytes, checksum: 3d70392d30b6b18a8ab0f79aa206e435 (MD5) Previous issue date: 2011-06-21 / In a real process, all used resources, whether physical or developed in software, are subject to interruptions or operational commitments. However, in situations in which operate critical systems, any kind of problem may bring big consequences. Knowing this, this paper aims to develop a system capable to detect the presence and indicate the types of failures that may occur in a process. For implementing and testing the proposed methodology, a coupled tank system was used as a study model case. The system should be developed to generate a set of signals that notify the process operator and that may be post-processed, enabling changes in control strategy or control parameters. Due to the damage risks involved with sensors, actuators and amplifiers of the real plant, the data set of the faults will be computationally generated and the results collected from numerical simulations of the process model. The system will be composed by structures with Artificial Neural Networks, trained in offline mode using Matlab? / Em um processo real, todos os recursos utilizados, sejam f?sicos ou desenvolvidos em software, est?o sujeitos a interrup??es ou a comprometimentos operacionais. Contudo, nas situa??es em que operam os sistemas cr?ticos, qualquer tipo de problema pode vir a trazer grandes consequ?ncias. Sabendo disso, este trabalho se prop?e a desenvolver um sistema capaz de detectar a presen?a e indicar os tipos de falhas que venham a ocorrer em um determinado processo. Para implementa??o e testes da metodologia proposta, um sistema de tanques acoplados foi escolhido como modelo de estudo de caso. O sistema desenvolvido dever? gerar um conjunto de sinais que notifiquem o operador do processo e que possam vir a ser p?s-processados, possibilitando que sejam feitas altera??es nas estrat?gias ou nos par?metros dos controladores. Em virtude dos riscos envolvidos com rela??o ? queima dos sensores, atuadores e amplificadores existentes na planta real, o conjunto de dados das falhas ser? gerado computacionalmente e os resultados coletados a partir de simula??es num?ricas do modelo do processo, n?o havendo risco de dano aos equipamentos. O sistema ser? composto por estruturas que fazem uso de Redes Neurais Artificiais, treinadas em modo offline pelo software matem?tico Matlab?

O recente desenvolvimento de uma teoria crítica dos sistemas, de Gunther Teubner a Andreas Fischer-Lescano, abriu novos horizontes teóricos para aqueles que se propõe a estudar a sociedade e o sistema jurídico. A construção de uma teoria crítica sob condições sistêmicas possibilitou o uso conjunto de temas e conceitos teóricos provenientes da teoria crítica da primeira geração da Escola de Frankfurt (crítica imanente, antagonismos sociais, reificação, dialética do esclarecimento) e da teoria dos sistemas (paradoxo, sistema, sociedade mundial). Partindo disso, o sistema jurídico foi analisado nas dimensões da justiça (como fórmula contingente e transcendente) e de sua crítica imanente como atitude transcendente, especialmente em face de sua tendência em se autorreproduzir como ordem social reificada que gera injustiça pelos excessos de justiça. Para alcançar essas conclusões, este trabalho se propôs a analisar o cenário da sociedade moderna no qual nasce a teoria crítica dos sistemas (Parte 1), lançando bases para os aspectos estruturais e semânticos sobre os quais ela se apoia. Seguidamente, foram estabelecidos os pressupostos teóricos básicos da teoria crítica da Escola de Frankfurt e da teoria dos sistemas de Luhmann (Parte 2) com o fim específico de colher os elementos essenciais à construção de uma teoria crítica dos sistemas voltada para o estudo do sistema jurídico. Logrado esse ponto, focou-se a análise do sistema jurídico e de sua evolução até alcançar sua atual condição na forma de um direito global na sociedade fragmentada (Parte 3). A partir disso a justiça autossubversiva e a crítica imanente do direito foram abordadas em seus aspectos essenciais e possibilitadores de uma autotranscendência sistêmica, capaz de tornar o direito mais responsivo com relação ao seu ambiente, limitando a irracionalidade racional inerente a uma ordem social reificada. A presente dissertação propõe dar mais um passo no sentido do desenvolvimento de uma teoria crítica dos sistemas aplicada ao direito, diagnosticando os dilemas contemporâneos e ao mesmo tempo, apontando os desafios existentes numa sociedade mundial paradoxalmente marcada pela possibilidade de hipertrofia sistêmica das ordens sociais reificadas e pelos processos de constitucionalização que buscam limitar essas ordens. / The recent development of critical systems theory, from Gunther Teubner to Andreas Fischer-Lescano, opened new horizons for the theorists who propose to study the society and the legal system. The construction of a critical theory under systemic conditions allows the joint use of theoretical concepts and themes from the first generation of the Frankfurt School (immanent critique, social antagonisms, reification, Dialectic of Enlightenment) and systems theory (paradox, systems, global society). Starting from this, the legal system was analyzed in the dimensions of justice (as contingent and transcendent formula) and its immanent critique as transcendent attitude, especially against the tendency to self-reproduce as reified social order, which produces injustices because excess of the justice. To reach these conclusions, this study aims to analyze the condition of modern society in which the critical systems theory arises (Part 1), laying the foundation for structural and semantic aspects on which it stands. Subsequently was established the basic theoretical premises of critical theory of the Frankfurt School and the systems theory of Niklas Luhmann (Part 2) with the specific purpose of collecting the essential elements to build a critical systems theory facing the study of the legal system. Reached this point, focused on the analysis of the legal system and its evolution to reach its current status of a global law in a fragmented society (Part 3). Like this the self-subversive justice and the immanent critique of the law have focused on key aspects that enable a systemic self-transcendence, able to make the law more responsive regarding to its environment by limiting its rational irrationality, which implies a reified social order. This thesis proposes give a step further towards the development of a critical theory applied to the law systems, diagnosing contemporary dilemmas and at the same time, pointing out the challenges of a global society paradoxically marked by the possibility of systemic hypertrophy stemmed from reified social orders and the constitutionalization processes that seek to limit such orders.

Data-driven decision support systems, such as data warehouses, are extremely costly to develop. Forty one per cent of data warehouse development practitioners have experienced project failures. These projects were either completed after exceeding budget and time limits, or not at all. Some influential data warehousing authors advocate user involvement as a solution, while others focus on technical factors to improve data warehouse success. This study proposes a framework for data warehousing success based on systems thinking methodology. Systems thinking implies a holistic approach to problem solving. A system is a set of interrelated elements. A systems approach represents a broad view, taking all aspects into account and concentrating on interactions between different parts of the problem. This study investigates the practices of data warehousing professionals from a systems thinking point of view, before proposing a framework for the explicit use of specific systems thinking methodologies in data warehouse development. Interpretive case study research is used to investigate practices of data warehousing professionals in three different organisations. Pattern matching is used to analyse collected data. This is done by mapping practices to different systems thinking perspectives. However, the theory component of the thesis is not a description of current data warehousing practices from a systems thinking point of view, as in typical interpretive research. The theory component relates more to critical research in that it is meant to change data warehousing practices towards specific systems thinking methodologies. The proposed framework incorporates three sources of information. These are a literature study on systems thinking philosophy, methodology and practice; a literature study on data warehousing and data warehousing success factors; and the results of case studies on current practices of data warehousing professionals analysed from a systems thinking perspective. The framework gives a methodological foundation for a holistic approach to data warehousing with maximum user involvement. It views a data warehouse as a system with typical systems characteristics, such as specified objectives relating to the organisation’s objectives, an environment, available resources, specified components and effective management. / Thesis (PhD (Information Technology))--University of Pretoria, 2006. / Informatics / unrestricted

This thesis deals with the critical systems thinking (CST) and its necessity and usability within a commercial company. Critical systems thinking is defined and explained from different perspectives, first as a specific way of approaching a problem, but as a tool for problem solving as well. The thesis also details the specific skills of critical systems thinking and systems archetypes and identifies some interrelations between CST and a specific commercial company with its needs. The practical part is focused on the process of solving specific problems using critical systems thinking, it also discusses the benefits and limitations and evaluates the overall necessity of CST for a commercial company.