Yes / The Stream X-Machine (SXM) testing method provides strong and repeatable guarantees of functional correctness, up to a specification. These qualities make the method attractive for software certification, especially in the domain of brokered cloud services, where arbitrage seeks to substitute functionally equivalent services from alternative providers. However, practical obstacles include: the difficulty in providing a correct specification, the translation of abstract paths into feasible concrete tests, and the large size of generated test suites. We describe a novel SXM verification and testing method, which automatically checks specifications for completeness and determinism, prior to generating complete test suites with full grounding information. Three optimisation steps achieve up to a ten-fold reduction in the size of the test suite, removing infeasible and redundant tests. The method is backed by a set of tools to validate and verify the SXM specification, generate technology-agnostic test suites and ground these in SOAP, REST or rich-client service implementations. The method was initially validated using seven specifications, three cloud platforms and five grounding strategies. / European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 328392, the Broker@Cloud project [11].

In recent years, there has been a ood of continuously changing information from a variety of web resources such as web databases, web sites, web services and programs. Online Social Networks (OSNs) represent such a eld where huge amounts of information are being posted online over time. Due to the nature of OSNs, which o er a productive source for qualitative and quantitative personal information, researchers from various disciplines contribute to developing methods for extracting data from OSNs. However, there is limited research which addresses extracting data automatically. To the best of the author's knowledge, there is no research which focuses on tracking the real time changes of information retrieved from OSN pro les over time and this motivated the present work. This thesis presents di erent approaches for automated Data Extraction (DE) from OSN: crawler, parser, Multi Agent System (MAS) and Application Programming Interface (API). Initially, a parser was implemented as a centralized system to traverse the OSN graph and extract the pro- le's attributes and list of friends from Myspace, the top OSN at that time, by parsing the Myspace pro les and extracting the relevant tokens from the parsed HTML source les. A Breadth First Search (BFS) algorithm was used to travel across the generated OSN friendship graph in order to select the next pro le for parsing. The approach was implemented and tested on two types of friends: top friends and all friends. In case of top friends, 500 seed pro les have been visited; 298 public pro les were parsed to get 2197 top friends pro les and 2747 friendship edges, while in case of all friends, 250 public pro les have been parsed to extract 10,196 friends' pro les and 17,223 friendship edges. This approach has two main limitations. The system is designed as a centralized system that controlled and retrieved information of each user's pro le just once. This means that the extraction process will stop if the system fails to process one of the pro les; either the seed pro le ( rst pro le to be crawled) or its friends. To overcome this problem, an Online Social Network Retrieval System (OSNRS) is proposed to decentralize the DE process from OSN through using MAS. The novelty of OSNRS is its ability to monitor pro les continuously over time. The second challenge is that the parser had to be modi ed to cope with changes in the pro les' structure. To overcome this problem, the proposed OSNRS is improved through use of an API tool to enable OSNRS agents to obtain the required elds of an OSN pro le despite modi cations in the representation of the pro le's source web pages. The experimental work shows that using API and MAS simpli es and speeds up the process of tracking a pro le's history. It also helps security personnel, parents, guardians, social workers and marketers in understanding the dynamic behaviour of OSN users. This thesis proposes solutions for web database processing on data extraction from OSNs by the use of parser and MAS and discusses the limitations and improvements. / Taibah University

Safety-critical systems have garnered increasing attention, particularly regarding their dependability analysis. In modern times, these systems comprise numerous components, making it crucial to verify that lower-level components adhere to their specifications will ensure the overall system’s compliance with its top-level specification. However, two issues arise in this verification process. Firstly, many industrial applications lack lower-level natural-language specifications for their components, relying solely on toplevel specifications. Secondly, many current verification algorithms need to explore the continuous time evolution of the behavioral combinations of these components, and the combination of components to be explored will rise exponentially with the number of components. To address these challenges, this paper presents significant contributions. Firstly, it introduces a novel method that leverages the structures of redundancy systems to create naturallanguage specifications for components derived from a top-level specification. This approach facilitates a more efficient decomposition of the top-level specification, allowing for greater ease in handling component behaviors. Secondly, the proposed method is successfully applied to Scania’s brake system, leading to the decomposition of its top-level specification. To verify this decomposition, an existing verification algorithm is selected, and the results are impressive. The proposed method effectively addresses the issue of exponential growth in component behavior combinations, which was previously mentioned. Specifically, in the case of the Scania brake system, the number of combinations is dramatically reduced from 27 to a mere 13, showcasing the significant improvement achieved with the new method. / Säkerhetskritiska system har fått ökad uppmärksamhet, särskilt när det gäller deras pålitlighetsanalys. I moderna tider består dessa system av talrika komponenter, vilket gör det avgörande att verifiera att komponenter på lägre nivå följer sina specifikationer för att säkerställa att hela systemet följer sin övergripande specifikation. Två utmaningar uppstår dock i denna verifieringsprocess. För det första saknar många industriella tillämpningar naturligspråksspecifikationer för komponenter på lägre nivå och förlitar sig enbart på övergripande specifikationer. För det andra behöver många nuvarande verifieringsalgoritmer utforska de kontinuerliga tidsutvecklingarna av beteendekombinationer hos dessa komponenter, och antalet kombinationer som ska utforskas ökar exponentiellt med antalet komponenter. För att tackla dessa utmaningar presenterar den här artikeln betydande bidrag. För det första introducerar den en ny metod som utnyttjar strukturer i redundanta system för att skapa naturligspråksspecifikationer för komponenter som härleds från en övergripande specifikation. Denna metod underlättar en mer effektiv uppdelning av övergripande specifikation, vilket gör det enklare att hantera komponentbeteenden. För det andra tillämpas den föreslagna metoden framgångsrikt på Scanias bromssystem, vilket leder till en uppdelning av dess övergripande specifikation. För att verifiera denna uppdelning väljs en befintlig verifieringsalgoritm, och resultaten är imponerande. Den föreslagna metoden hanterar effektivt problemet med exponentiell tillväxt i komponentbeteendekombinationer, vilket tidigare nämnts. Specifikt, för Scanias bromssystem minskar antalet kombinationer dramatiskt från 27 till endast 13, vilket tydligt visar den betydande förbättring som uppnåtts med den nya metoden.

<p>Formal methods such as Event-B are a widely used approach for developing critical systems. This thesis demonstrates that creating models and proving the consistency of the models at the requirements level during software (system) development is an effective way to reduce the occurrence of faults and errors in a practical application. An insulin infusion pump (IIP) is a complicated and time critical system. This thesis uses Event-B to specify models for an IIP, based on a draft requirements document developed by the US Food and Drug Administration (FDA). Consequently it demonstrates Event-B can be used effectively to detect the missing properties, the missing quantities, the faults and the errors at the requirements level of a system development. The IIP is an active and reactive time control system. To achieve the goal of handling timing issues in the IIP system, we made extensions of an existing time pattern specified using Event-B to enrich the semantics of the Event-B language. We created several sets to model the activation times of different events and the union of these time sets defines a global time activation set. The tick of global time is specified as a progress tick event. All the actions in an event are triggered only when the global time in the time tick event matches the time specified in the event. Time is deleted from the corresponding time set, but not the corresponding global time set while the event is triggered. A time point is deleted from the global time set only when there are no pending actions for that time point. Through discharging proof obligations using Event-B, we achieved our goal of improving the requirements document.</p> / Master of Computer Science (MCS)

Two of the main needs when developing an information system for an organization are that system analysts know and understand the application domain and that the system properly supports the business processes of the organization. Consequently, elicitation of system requirements from business process models has been acknowledged as a suitable activity to deal with that needs. In addition, system requirements must be linked to subsequent development stages. However, system analysts can face many challenges when performing these activities. They may have problems communicating with customer stakeholders and may need to analyse and operationalize the purpose of the information system. Furthermore, system analysts must bridge the gap between business and system domains for specification of system requirements, specify different types of system requirements and guarantee that their specification is precise, consistent and homogeneous. In relation to object-oriented conceptual modelling-based information system development, system analysts must also avoid potential problems that may arise when a conceptual schema is created from system requirements as part of their link with subsequent development stages. For example, a conceptual schema can be incomplete and/or inconsistent if it is not properly managed. As a solution, this thesis presents a methodological approach for business process-based requirements specification and object-oriented conceptual modelling of information systems. The approach consists of four stages: organizational modelling, purpose analysis, specification of system requirements and derivation of object-oriented diagrams. By following the design research methodology for performing research in information systems, the methodological approach has been designed on the basis of many existing ideas and principles in academia and industry and provides new principles, mechanisms and guidance to address the challenges presented above. / De La Vara González, JL. (2011). Business process-based requirements specification and object-oriented conceptual modelling of information systems [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/11445

[EN] The dynamics of linear operators, namely linear dynamics, is mainly concerned with the behaviour of iterates of linear transformations. Hypercyclicity is the study of linear operators that possess a dense orbit. Although the first examples of hypercyclic operators are due to G. D. Birkhoff (in 1929), G. R. MacLane (in 1952) and S. Rolewicz (in 1969), we can date the birth of the linear dynamics in 1982 with the unpublished PhD thesis of C. Kitai. Since then, many mathematicians have contributed to the development of this flourishing new area of the analysis. Linear dynamics connects functional analysis and dynamics. As for the classical dynamical systems, one can study the dynamics of linear operators from a topological point of view. In this context, we state that an operator has the specification property (SP). Precisely, the aim of this PhD thesis is to study the specification property on linear dynamical systems. A continuous map on a compact metric space satisfies the specification property if one can approximate pieces of orbits by a single periodic orbits with a certain uniformity. This Doctoral dissertation is a compendium of articles on the specification property. It is structured in four parts preceded by a chapter which introduces the notation, definitions and the basic results that will be needed throughout the thesis. The shift operators on sequence spaces constitute one of the most important test ground for discrete linear dynamical systems. Due to its simple structure, every time you introduce a new property in linear dynamics it is common to check it on weighted shifts operators. It is for this reason that the first part of this research work is devoted to study the specification property for unilateral and bilateral backward shift operators on weighted l^p-spaces and the relationship with other dynamical properties. In Chapter 3 we extend the results on the SP to shift operators on separable sequence F-spaces. An F-space is a vector space that is endowed with an F-norm and that is complete under the induced metric. The notion of an F-norm has the advantage that one can largely argue as if one was working in a Banach space. One need to be aware of the fact that the positive homogeneity of a norm is no longer available. The spaces l^p with 0 < p < 1 are F-spaces. Chaotic dynamical systems have received a great deal of attention in recent years. An operator is chaotic if it has a dense set of periodic points. The specification property is an interesting and rather strong notion of chaos (in the topological sense). We also consider a qualitative strengthening of hypercyclicity namely frequent hypercyclicity. It was introduced by Bayart and Grivaux, motivated by Birkhoff's ergodic theorem. An operator is frequently hypercyclic if there is some element whose orbit meets every non-empty open set very often. In Chapter 4 the specification property is deeply studied for linear and continuous operators on separable F-spaces. In addition, we are interested in finding out its relation with other dynamical properties such as mixing, Devaney chaos and frequent hypercyclicity. The results that we have achieved have been accepted to be publish in Journal of Mathematical Analysis and Applications. Finally, in the last chapter of this dissertation, we examine the specification property for strongly continuous semigroups on Banach spaces, that is, for C_0-semigroups. They can viewed as the continuous-time analogue of the discrete-time case of iterates of a single operator; in other words, the parameter in the continuous case plays the role of the iterations in the discrete case. Now the translation semigroups substitute the shift operators as test classes. Once again, we study the relationship between the specification property and mixing, chaos and frequent hypercyclicity properties of a C_0-semigroup. / [ES] La dinámica de operadores lineales, o simplemente dinámica lineal, estudia las órbitas generadas por las iteraciones de una transformación lineal. La hiperciclicidad es el estudio de los operadores lineales que poseen una órbita densa. Si bien G. D. Birkhoff (en 1929), G. R. MacLane (en 1952) y S. Rolewicz (en 1969) obtuvieron ejemplos de operadores lineales hipercíclicos, podemos fijar el nacimiento de la dinámica lineal en 1982 con la tesis de C. Kitai. Desde entonces muchos matemáticos han contribuido al desarrollo de esta floreciente área del análisis. La dinámica lineal conecta el análisis funcional y la dinámica. Al igual que en sistemas dinámicos clásicos, podemos estudiar la dinámica de operadores lineales desde un punto de vista topológico. En este contexto, hablamos de que un operador tiene la propiedad de especificación (SP). Precisamente, al estudio de la propiedad de especificación en sistemas dinámicos lineales está dedicada la presente tesis doctoral. Una aplicación continua en un espacio métrico satisface la propiedad de especificación si para cualquier familia de puntos podemos aproximar, con una cierta uniformidad, partes de sus órbitas por una sola órbita de un punto periódico. La tesis es un compendio de artículos sobre la propiedad de especificación. Se estructura en cuatro partes precedidas de un capítulo dedicado a introducir la notación, definir los conceptos y enunciar los resultados de ámbito general que van a ser utilizados en el resto de la memoria. Los operadores "shift" (desplazamiento) constituyen una de las clases más importantes, como campo de pruebas, en sistemas dinámicos lineales discretos. Debido a su estructura simple, siempre que se introduce un nuevo concepto en dinámica lineal es habitual comprobarlo sobre shifts ponderados. Por este motivo, en la primera parte de esta memoria, se estudia la propiedad de especificación para operadores desplazamiento unilaterales y bilaterales en espacios l^p ponderados y la relación con otras propiedades dinámicas. En el capítulo 3 se generalizan los resultados sobre la propiedad SP a operadores desplazamiento en F-espacios separables de sucesiones. Un F-espacio es un espacio vectorial, dotado de una F-norma, que es completo con la métrica inducida. La noción de F-norma tiene la ventaja de que permite trabajar como en un espacio de Banach llevando cuidado con la homogeneidad de la norma que ahora no se cumple Los sistemas dinámicos caóticos han recibido gran atención en los últimos años. Un operador lineal es caótico si admite un conjunto denso de puntos periódicos. La propiedad de especificación es una noción de caos (en el sentido topológico) más potente que la debida a Devaney. Otra variante más fuerte que la hiperciclicidad es la hiperciclicidad frequente. Este concepto fue introducido por Bayart y Grivaux motivados por el teorema ergódico de Birkhoff. Un operador es frecuentemente hipercíclico si algún elemento tiene una órbita que corta muy a menudo a cada conjunto abierto no vacío. En el capítulo 4 de esta tesis se estudia con profundidad la propiedad de especificación para operadores lineales y continuos definidos en F-espacios separables. Los resultados que presentamos han sido aceptados para su publicación en J. Math. Anal. Appl. Finalmente, en la cuarta parte de este trabajo, se extiende la propiedad de especificación a semigrupos de operadores fuertemente continuos en espacios de Banach, esto es, C_0-semigrupos. Estos operadores pueden verse como la versión continua del caso discreto correspondiente a las iteraciones de un único operador. Ahora, la labor de los operadores desplazamiento en espacios de sucesiones como clases de prueba la desempeñan los semigrupos de traslación. Al igual que en capítulos anteriores, se estudia la relación de la propiedad SP para C_0-semigrupos con otras propiedades dinámicas. / [CA] La dinàmica d'operadors lineals, o simplement dinàmica lineal, estudie les òrbites generades per les iteracions d'una transformació lineal. La hiperciclicitat es el estudi dels operadors lineal que posseeixen una òrbita densa. Si bé G. D. Birkhoff (en 1929), G. R. MacLane (en 1952) y S. Rolewicz (en 1969) van obtenir exemples d'operadors lineals hipercíclics, podem fixar el naixement de la dinàmica lineal en 1982 amb la tesi de C. Kitai [68]. Des de llavors molts matemàtics han contribuït al desenvolupament d'esta florent area de l'anàlisi. La dinàmica lineal connecta el anàlisi funcional y la dinàmica. Igual que en sistemes dinàmics clàssics, podem estudiar la dinàmica d'operadors lineals des d'un punt de vista topològic. En eixe context, parlem que un operador té la propietat d'especificació (SP). Precisament, al estudi de la propietat d'especificació en sistemes dinàmics lineals està dedicada la present tesi doctoral. Una aplicació continua en un espai mètric compleix la propietat d'especificació si per a qualsevol família de punts podem aproximar, amb certa uniformitat, parts de les seues òrbites per una sola òrbita d'un punt periòdic. La tesi es un compendi de articles sobre la propietat d'especificació. S'estructura en quatre parts precedides d'un capítol dedicat a introduir la notació, definir els conceptes i enunciar els resultats d'àmbit general que seran utilitzats en la resta de la memòria. Els operadors "shifts" (desplaçaments) constitueixen una de les classes més importants, com a camp de proves, en sistemes dinàmics lineals discrets. Degut a la seua estructura simple, sempre que es introdueix un nou concepte en dinàmica lineal es habitual comprovar-ho sobre shifts ponderats. Per esta raó, en la primera part d'esta memòria, s'estudia la propietat d'especificació per a operadors desplaçament unilaterals i bilaterals en espais l^p ponderats i la relació amb altres propietats dinàmiques. En el capítol 3 es generalitzen els resultats sobre la propietat SP a operadors desplaçament en F-espais separables de successions. Un F-espai es un espai vectorial, dotat d'una F-norma, que és complet amb la mètrica induida. La noció de F-norma té l'avantatge que permet treballar com en un espai de Banach anant en compte amb l'homogeneitat de la norma que ara no es compleix. Els espais l^p amb 0 < p < 1 són exemples de F-espais. Els sistemes dinàmics caòtics han rebut gran atenció en els últims anys. Un operador lineal és caòtic si admet un conjunt dens de punts periòdics. La propietat d'especificació és una noció de caos (en el sentit topològic) més potent que la deguda a Devaney. Una altra variant més forta que la hiperciclicitat és la hiperciclicitat freqüent. Aquest concepte va ser introduït per Bayart i Grivaux motivats per el teorema ergòdic de Birkhoff. Un operador és freqüentment hipercíclic si algun element té una òrbita que talle molt sovint a cada conjunt obert no vuit. En el capítol 4 d'esta tesi se estudie amb profunditat la propietat d'especificació per a operadors lineals i continus definits en F-espais separables. També s'incideix en la connexió de dita propietat amb altres propietats dinàmiques. Els resultats que presentem han estat acceptats per a la seva publicació en J. Math. Anal. Appl. Finalment, en la quarta part d'aquest treball, s'estén la propietat d'especificació a semigrups d'operadors fortament continus en espais de Banach, això és, C_0-semigrups. Aquests operadors poden veure's com la versió continua del cas discret corresponen a les iteracions d'un únic operador; en altres paraules, el paper de les iteracions en el cas discret ho assumeix el paràmetre en el cas continu. Ara, la labor del operadors desplaçament en espais de successions com classes de prova l'exerceixen els semigrups de translació. Igual que en capítols anteriors, s'estudia la relació de la propietat SP per a C0-semigrups amb altres propie / Bartoll Arnau, S. (2016). The specification property in linear dynamics [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/61633

The growing need for computer software in different sectors of activity, (health, agriculture, industries, education, aeronautic, science and telecommunication) together with the increasing reliance of the society as a whole on information technology, is placing a heavy and fast growing demand on complex and high quality software systems. In this regard, the anticipation has been on non-functional requirements (NFRs) engineering and formal methods. Despite their common objective, these techniques have in most cases evolved separately. NFRs engineering proceeds firstly, by deriving measures to evaluate the quality of the constructed software (product-oriented approach), and secondarily by improving the engineering process (process-oriented approach). With the ability to combine the analysis of both functional and non-functional requirements, Goal-Oriented Requirements Engineering (GORE) approaches have become de facto leading requirements engineering methods. They propose through refinement/operationalisation, means to satisfy NFRs encoded in softgoals at an early phase of software development. On the other side, formal methods have kept, so far, their promise to eliminate errors in software artefacts to produce high quality software products and are therefore particularly solicited for safety and mission critical systems for which a single error may cause great loss including human life. This thesis introduces the concept of Complementary Non-functional action (CNF-action) to extend the analysis and development of NFRs beyond the traditional goals/softgoals analysis, based on refinement/operationalisation, and to propagate the influence of NFRs to other software construction phases. Mechanisms are also developed to integrate the formal technique Z/Object-Z into the standardised User Requirements Notation (URN) to formalise GRL models describing functional and non-functional requirements, to propagate CNF-actions of the formalised NFRs to UCMs maps, to facilitate URN construction process and the quality of URN models. / School of Computing / D. Phil (Computer Science)

This thesis investigates the expressiveness of specification languages for stochastic safety-critical systems, addressing the need for expressiveness in describing system behaviour formally. Through a case study and specification language enhancements, the research explores the impact of different frameworks on a set of specifications. The results highlight the importance of continuous development in the specification languages to meet the complex behaviours of systems with probabilistic properties. The findings emphasise the need for extending the chosen specification languages more formally, to ensure that the languages can capture the complexity of the systems they describe.  The research contributes valuable insights into improving the expressiveness of specification languages for ensuring system safety and operational reliability.

This research investigates tolerance strategies for modular systems on a project specific basis. The objective of the proposed research is to form a guideline for optimizing the construction costs/risks with the aim of developing an optimal design of resilient modular systems. The procedures for achieving the research objective included: (a) development of 3D structural analysis models of the modules, (b) strength/stability investigation of the structure, (c) developing the fabrication cost function, (e) checking elastic and inelastic distortion, and (f) constructing the site-fit risk functions. The total site-fit risk function minimizes the cost/risk associated with fabrication, transportation; alignment, rework, and safety, while maximizing stiffness in terms of story drift values for site re-alignment and fitting alternatives. The fabrication cost function was developed by collecting 61 data points for the investigated module chassis using the SAP2000 software while reducing the initial section sizes, in addition to the fabrication costs at each step (61 steps). With the reduction of the structural reinforcement, story drift values increase, therefore there will be a larger distortion in the module. This generic module design procedure models a trade-off between the amount of reinforcement and expected need for significant field alterations. Structural design software packages such as SAP2000, AutoCAD, and Autodesk were used in order to model and test the module chassis. This research hypothesizes that the influential factors in the site-fit risk functions are respectively: fabrication, transportation, alignment, safety, and rework costs/risks. In addition, the site-fit risk function provides a theoretical range of possible solutions for the construction industry. The maximum allowable modular out-of-tolerance value, which requires the minimum amount of cost with respect to the defined function, can be configured using this methodology. This research concludes that over-reinforced or lightly-reinforced designs are not the best solution for mitigating risks, and reducing costs. For this reason the site-fit risk function will provide a range of pareto-optimal building solutions with respect to the fabrication, transportation, safety, alignment, and rework costs/risks.

Public sector organisations are established in order to promote the quality of citizen's lives through the provision of public services. However, the demands for public services often outstrip the limited resources at the disposal of the public sector for the delivery of such services. Public-private partnerships (PPPs) are emerging as an important tool of public policy to deliver public infrastructure and the attendant services. The main aim of this study is to establish the extent to which PPPs can be used to improve the quality of the delivery of secondary education in the Gaborone City area in Botswana. The study includes a conceptual analysis of the nature of the public services in general, and in particular, the nature and the provision of secondary education in Botswana with specific reference to the Gaborone City area. The study also includes a conceptual analysis of PPPs as gleaned from published literature. Various dimensions of PPPs are analysed and these include but are not limited to definitions, benefits, models and the antecedents for the successful implementation of PPPs. Among the various models that are analysed in the study, the design, build, operate and finance (DBOF) model is preferred for improving the quality of the delivery of secondary education in the Gaborone City area in Botswana. In addition to the conceptual analysis, an empirical research study is undertaken in which the secondary school heads are the respondents to a structured questionnaire. The results of the empirical research support the conceptual analysis to the extent that in both cases, it is possible to improve the quality of the delivery of secondary education through PPPs. More secondary schools can be built and more facilities be made available to schools. Through the use of PPPs, most if not all learners can receive the entire secondary education programme, from junior to senior secondary education. Existing secondary schools can be modernised through PPPs. Ancillary services can be delivered by the organisations that have the necessary expertise. Certain antecedents for the successful implementation of PPPs are necessary. Through PPPs, secondary schools can be made attractive and intellectually stimulating. / Public Administration / (D.Litt. et Phil. ( Public Administration))