Weak persistency semantics from the ground up: formalising the persistency semantics of ARMv8 and transactional models

Emerging non-volatile memory (NVM) technologies promise the durability of disks with the performance of volatile memory (RAM). To describe the persistency guarantees of NVM, several memory persistency models have been proposed in the literature. However, the formal persistency semantics of mainstream hardware is unexplored to date. To close this gap, we present a formal declarative framework for describing concurrency models in the NVM context, and then develop the PARMv8 persistency model as an instance of our framework, formalising the persistency semantics of the ARMv8 architecture for the first time. To facilitate correct persistent programming, we study transactions as a simple abstraction for concurrency and persistency control. We thus develop the PSER (persistent serialisability) persistency model, formalising transactional semantics in the NVM context for the first time, and demonstrate that PSER correctly compiles to PARMv8. This then enables programmers to write correct, concurrent and persistent programs, without having to understand the low-level architecture-specific persistency semantics of the underlying hardware

Small buyer perspective on dependence in buyer-supplier relationships and purchasing strategy: A case study

Confidential unrtil 28 May 20182018-05-2

Emerging research directions in computer science : contributions from the young informatics faculty in Karlsruhe

In order to build better human-friendly human-computer interfaces, such interfaces need to be enabled with capabilities to perceive the user, his location, identity, activities and in particular his interaction with others and the machine. Only with these perception capabilities can smart systems ( for example human-friendly robots or smart environments) become posssible. In my research I\u27m thus focusing on the development of novel techniques for the visual perception of humans and their activities, in order to facilitate perceptive multimodal interfaces, humanoid robots and smart environments. My work includes research on person tracking, person identication, recognition of pointing gestures, estimation of head orientation and focus of attention, as well as audio-visual scene and activity analysis. Application areas are humanfriendly humanoid robots, smart environments, content-based image and video analysis, as well as safety- and security-related applications. This article gives a brief overview of my ongoing research activities in these areas

Contribution to dynamic reconfiguration in component-based systems: consistency and non-functional properties specification

Le travail réalisé dans le cadre de cette thèse a deux objectifs principaux. Le premier est de contribuer `à la spécification de la reconfiguration dynamique des systèmes à base de composants. Le deuxième objectif est de s´sélectionner la configuration optimale parmi un ensemble de configurations qui fournissent des fonctionnalités identiques ou similaires. Le processus de sélection dépend des propriétés non-fonctionnelles du système. La propriété de reconfigurabilité est essentielle pour de nombreux systèmes à base de composants contemporains. En effet, cette propriété améliore la disponibilité, l'adaptabilité, l'évolutivité, la maintenabilité et la performance des systèmes tels que les systèmes avioniques, les commutateurs de télécommunications et les systèmes commerciaux. Pour ces systèmes, l'arrêt de longue durée n'est pas admissible pour des raisons s´sécuritaires ou économiques. L'adaptabilité et l'evolvabilité sont également des caractéristiques importantes pour ces systèmes qui ont besoin d'inclure des changements de l'environnement ou des nouvelles exigences des utilisateurs dans le logiciel. Toutes ces motivations plus montrent l'importance de permettre, dès la conception, la reconfiguration dynamique de systèmes. La reconfiguration est la capacité de modifier la structure ou le comportement d'un système à l'exécution et sans l'arrêter complétement. Le travail présenté dans cette thèse étudie les mécanismes et les techniques pour fournir la reconfigurabilité aux systèmes à base de composants. La fourniture de reconfigurabilité nécessite la prise en considération de la cohérence du système pendant et après la reconfiguration. Il y a deux sortes de cohérence : cohérence globale et cohérence locale. Dans cette thèse, nous proposons une approche pour préserver la cohérence globale d'un système à base de composants reconfigurable en utilisant un langage formel déclaratif, Alloy. Une autre approche est proposée pour préserver la cohérence locale en analysant la relation entre la dépendance indirecte et la reconfiguration dynamique. Enfin, la sélection de configuration consiste à choisir la configuration la plus optimale à partir d'un ensemble de choix dans le but de maximiser la satisfaction de l'utilisateur. Une approche proposée pour faire le meilleur choix en fonction des préférences de l'utilisateur exprimées sur des métriques non-fonctionnellesThe research of this thesis has two main goals. The first goal is to provide the reconfigurability feature to the component-based systems. The second goal is to select the optimal configuration from a set of configurations, which provide similar functionality. The selection process depends on the non-functional properties of the system. Reconfigurability is essential feature for many contemporary component-based systems. Reconfigurability enhances the continuous availability, the adaptability, the evolvability, the maintainability, and the performance. Avionics systems, telecommunications switches and some commercial systems require the high availability. For these systems, long shutting down is not allowable due to economical or safety reasons. The adaptability and the evolvability are also important features for those systems which need to accommodate the environmental changes or the new requirements of software users. The maintainability and the performance are important requirements for a large category of systems. All the previous motivations and more show the importance of having the reconfigurability. Reconfigurability is the ability to change the system structure or the system behavior at running time without stopping it. The work presented in this thesis investigates the required mechanisms and techniques in order to provide the reconfigurability feature to a component-based system. The provision of the reconfigurability feature requires preserving the system consistency during and after the reconfiguration. The consistency has two kinds: global consistency and local consistency. In this thesis, we propose an approach to preserve the global consistency of a reconfigurable component-based system using declarative formal language. Another approach is proposed to preserve the local consistency during the reconfiguration. The second approach investigates the relationship between the indirect dependency and the dynamic reconfiguration. Configuration selection is to select the most optimal configuration from a set of alternatives in order to maximize the end user satisfaction. The thesis proposes an approach to make the best selection depending on the user preference

Impact of different leadership styles on the success of the project

This thesis examines the impact of various leadership styles on project success across different industries, including IT, construction, and healthcare. Through a combination of literature review and empirical research involving interviews with industry leaders, this study explores how transformational, transactional, authoritarian, and democratic leadership styles affect team motivation, project quality, and deadline adherence. The research identifies the strengths and weaknesses of each leadership style and evaluates their effectiveness in specific project scenarios. Transformational leadership is noted for its ability to inspire and innovate, making it ideal for dynamic sectors like technology. In contrast, transactional and authoritarian styles provide structure and discipline, suited for industries requiring stringent adherence to standards, such as construction. Furthermore, democratic leadership, with its emphasis on collective decision-making, is found to enhance creativity and employee satisfaction, which is crucial in education and healthcare projects. The study also incorporates a SWOT analysis to provide a detailed evaluation of each leadership style, offering insights into their potential impacts under various operational conditions. Key findings suggest that no single leadership style is universally effective; rather, project managers should adapt their leadership approach based on project requirements, team dynamics, and industry characteristics. The thesis concludes with recommendations for project leaders on selecting and tailoring leadership styles to optimize project outcomes and enhance team performance. This research contributes to the field of project management by providing a clearer understanding of how specific leadership styles can directly influence project success and by offering practical guidance for current and future project managers

A Concurrency and Time Centered Framework for Certification of Autonomous Space Systems

Future space missions, such as Mars Science Laboratory, suggest the engineering of some of the most complex man-rated autonomous software systems. The present process-oriented certification methodologies are becoming prohibitively expensive and do not reach the level of detail of providing guidelines for the development and validation of concurrent software. Time and concurrency are the most critical notions in an autonomous space system. In this work we present the design and implementation of the first concurrency and time centered framework for product-oriented software certification of autonomous space systems. To achieve fast and reliable concurrent interactions, we define and apply the notion of Semantically Enhanced Containers (SEC). SECs are data structures that are designed to provide the flexibility and usability of the popular ISO C++ STL containers, while at the same time they are hand-crafted to guarantee domain-specific policies, such as conformance to a given concurrency model. The application of nonblocking programming techniques is critical to the implementation of our SEC containers. Lock-free algorithms help avoid the hazards of deadlock, livelock, and priority inversion, and at the same time deliver fast and scalable performance. Practical lock-free algorithms are notoriously difficult to design and implement and pose a number of hard problems such as ABA avoidance, high complexity, portability, and meeting the linearizability correctness requirements. This dissertation presents the design of the first lock-free dynamically resizable array. Our approach o ers a set of practical, portable, lock-free, and linearizable STL vector operations and a fast and space effcient implementation when compared to the alternative lock- and STM-based techniques. Currently, the literature does not offer an explicit analysis of the ABA problem, its relation to the most commonly applied nonblocking programming techniques, and the possibilities for its detection and avoidance. Eliminating the hazards of ABA is left to the ingenuity of the software designer. We present a generic and practical solution to the fundamental ABA problem for lock-free descriptor-based designs. To enable our SEC container with the property of validating domain-specific invariants, we present Basic Query, our expression template-based library for statically extracting semantic information from C++ source code. The use of static analysis allows for a far more efficient implementation of our nonblocking containers than would have been otherwise possible when relying on the traditional run-time based techniques. Shared data in a real-time cyber-physical system can often be polymorphic (as is the case with a number of components part of the Mission Data System's Data Management Services). The use of dynamic cast is important in the design of autonomous real-time systems since the operation allows for a direct representation of the management and behavior of polymorphic data. To allow for the application of dynamic cast in mission critical code, we validate and improve a methodology for constant-time dynamic cast that shifts the complexity of the operation to the compiler's static checker. In a case study that demonstrates the applicability of the programming and validation techniques of our certification framework, we show the process of verification and semantic parallelization of the Mission Data System's (MDS) Goal Networks. MDS provides an experimental platform for testing and development of autonomous real-time flight applications

Improving the management of prison-based education staff through an examination of multi-agency psychological contracts

This study is set in the context of prison education. Contracted-out employment arrangements are becoming increasingly common and prison education services were put out to tender in 1993. Currently 27 contractors are responsible for education provision within the 138 state run prisons in England and Wales. One consequence of this employment arrangement is that prison-based education staff, working often exclusively within a prison, are employed by an organisation that is not necessarily geographically close to the prison in which they work. This study explores this employment relationship in the context of the psychological contract through investigating the contents of the psychological contracts of prison-based education staff perceived with their employer and with the host prison. Eighty-five semi-structured interviews, carried out across eleven prisons, used the critical incident technique to uncover prison-based education staff's perceptions of the obligations owed to them by their employer and by the host prison along with their perceptions of the obligations owed by themselves to their employer and to the host prison. Content analysis was carried out on the interview transcripts to reveal a hybrid psychological contract including relational and transactional items with both the employer and the host prison. The results suggest that prison-based education teams develop a strong sense of team identity and demonstrate their commitment to the team through pro-social behaviour in the form of team citizenship. There is also evidence that suggests prison-based education teams operate in a culture of intergroup differentiation which has implications for the way in which prison-education teams are managed. The academic contributions made by the study along with strategic implications for organisations employing prison-based education teams are discussed and recommendations for practice, both strategic and operational are made

Leadership in Small U.S. Industrial Machining and Fabricating Companies

Given the continuous advances with globalization and overall competition, small U.S. machining and fabrication companies (manufacturing) are required to constantly maintain a competitive advantage to stay relevant (Avolio, 2004; Cascio 1995). To help maintain that competitive advantage, leadership has been extensively researched for many years within multiple segments of the U.S. economy; however, specific focus has been neglected when it comes to transactional and transformational leadership styles within small U.S. industrial machining and fabricating companies. The focus of this research centers on three small industrial machining and fabricating businesses in the manufacturing sector. Distributing the multifactor leadership questionnaire (MLQ) this research investigates the leadership style of each businesses leader. The MLQ specifically focuses on the leadership styles that the leaders self-assess between transactional and transformational leadership and then leverage that information when the employees provide a 360-loop feedback, which rates the leader. The MLQ is the gold-star standard to evaluate transactional and transformational leadership (Bass & Avolio, 2000; Avolio & Bass, 2004). The MLQ additionally provides a rating on the outcomes of extra effort, effectiveness, and satisfaction from both the subordinates and leader, which this dissertation will focus on as well. Previous studies provide a solid foundation on transactional and transformational leadership within alternative environments other than small U.S. industrial machining and fabricating companies, which is the focus of this dissertation. This dissertation presents the findings that employees in an industrial environment would exhibit higher levels of extra effort, effectiveness, and satisfaction, provided the leader espouses more transformational leadership. Results revealed transformational leadership was significantly related to extra effort, effectiveness, and satisfaction. To the contrary, results revealed that transactional leadership was not significantly related to extra effort, effectiveness, and satisfaction. Additional results substantiated the findings listed above by conducting a Person correlation that showed transformational leadership scores were positively related to transactional leadership scores. To substantiate the study further results were compiled by conducting three fixed effect regressions analyzing the independent variables of transactional and transformational leadership scores from the employee self-reports, as well as one-sample t-tests that compared this studies MLQ results to the U.S. normative samples

Sourcing Innovation: probing Technology Readiness Levels with a design framework

International audienceSupplier-buyer exchanges are well addressed in literature except in the case of unknown objects. Sourcing Innovation, i.e. the process of finding external sources of innovation and then bringing those innovations into the firm should transform incoming unknown objects to ascribe them value. Technology Readiness Levels (TRL) have formalised the unknown in supplier-buyer exchanges in many industries for forty years but there is no evidence that they enable that transformation. We then use design theories, i.e. the Technology-Environment framework, to probe TRL through analysing ten cases combining documents analyses and longitudinal studies. We found that TRL avoid fixating on a low mature technology and are not an obstacle at genericity; however they fixate when the buyer waits a certain TRL prior exploring the new technology value. Finally TRL are unable to guide designers towards generativity notably because they embrace a definition of Environment focused on the prototyping method