High-Level Representation of Time in Diagrammatic Specification

AbstractThe notion of time is an important element in such systems as real-time embedded systems. Real-time systems have strict timing constraints, and their complexity is continuously increasing, making their design very challenging. This paper concerns a very high level of requirements specification used for system understanding and communication among stakeholders and as a base for development. It introduces a diagrammatic description of functional behavior of a system with nonfunctional constraints including timing plan. Specifically, this paper explores the presentation of time at this level of system description. The usability and feasibility of the proposed method are illustrated by applying it to examples

Digital Twin for Hybrid Installations

The product development and lifecycle management is constantly affected by digitalization. The same trend has been also observed in the simulation technology. The system simulation has evolved from applications with limited and specific use cases to more standardized and multi-disciplinary tools. The “Digital Twin” concept is the most recent advancement in this field where its definition is beyond a simulator. The concept arose from the “Industry 4.0” development and it can be described as a bi-directional communication between physical products data and their digital representation in the entire product lifecycle. A hybrid power module consists of components such as an engine, a gearbox, the generator sets, the batteries, and technologies for efficiently exploiting the mechanical energy form the engine and the electrical energy from the batteries. The modular product development necessitates adoption of systems engineering approaches and principles in order to handle the product lifecycle management appropriately. Handling the product lifecycle management for the hybrid power modules encompasses the integration of disengaged elements, data, and stakeholders throughout the product development. In order to address the abovementioned problem, model-based systems engineering approach incorporates available tools and technologies. A product lifecycle management platform and tools in hand like web services and functional mock-up interface justify the development of a digital twin application. This application must be able to reveal the adoption of system of systems view for hybrid power module development. This can be achieved by creating a reference system model and continuously enriching it with the product lifecycle data. To begin with the implementation of a digital twin application, systems engineering theories are studied, a software development lifecycle is chosen, prototypes of the application, and development technologies are selected. Lastly, the application is programmed and deployed. The digital twin application is embedded inside a product lifecycle management platform and exploits other resources and data alongside. The application is a simplified implementation of the “V” lifecycle model in systems engineering and achieves objectives like task-centered product development, value co-creation in business processes, product data management, simulation-based, and requirements validation among others

EOOLT 2007 – Proceedings of the 1st International Workshop on Equation-Based Object-Oriented Languages and Tools

Computer aided modeling and simulation of complex systems, using components from multiple application domains, such as electrical, mechanical, hydraulic, control, etc., have in recent years witness0065d a significant growth of interest. In the last decade, novel equation-based object-oriented (EOO) modeling languages, (e.g. Mode- lica, gPROMS, and VHDL-AMS) based on acausal modeling using equations have appeared. Using such languages, it has become possible to model complex systems covering multiple application domains at a high level of abstraction through reusable model components. The interest in EOO languages and tools is rapidly growing in the industry because of their increasing importance in modeling, simulation, and specification of complex systems. There exist several different EOO language communities today that grew out of different application areas (multi-body system dynamics, electronic circuit simula- tion, chemical process engineering). The members of these disparate communities rarely talk to each other in spite of the similarities of their modeling and simulation needs. The EOOLT workshop series aims at bringing these different communities together to discuss their common needs and goals as well as the algorithms and tools that best support them. Despite the short deadlines and the fact that this is a new not very established workshop series, there was a good response to the call-for-papers. Thirteen papers and one presentation were accepted to the workshop program. All papers were subject to reviews by the program committee, and are present in these electronic proceedings. The workshop program started with a welcome and introduction to the area of equa- tion-based object-oriented languages, followed by paper presentations and discussion sessions after presentations of each set of related papers. On behalf of the program committee, the Program Chairmen would like to thank all those who submitted papers to EOOLT'2007. Special thanks go to David Broman who created the web page and helped with organization of the workshop. Many thanks to the program committee for reviewing the papers. EOOLT'2007 was hosted by the Technical University of Berlin, in conjunction with the ECOOP'2007 conference

A model-based systems engineering framework for concept development

Thesis (S.M. in Engineering and Management)--Massachusetts Institute of Technology, Engineering Systems Division, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 148-151).The development of increasingly complex, innovative systems under greater constraints has been the trend over the past several decades. In order to be successful, organizations must develop products that meet customer needs more effectively than the competitors' alternatives. The development of these concepts is based on a broad set of stakeholder objectives, from which alternative designs are developed and compared. When properly performed, this process helps those involved understand the benefits and drawbacks of each option. This is crucial as firms need to effectively and quickly explore many concepts, and easily determine those most likely to succeed. It is generally accepted that a methodical design approach leads to the reduction in design flaws and cost over a product's life cycle. Several techniques have been developed to facilitate these efforts. However, the traditional tools and work products are isolated, and require diligent manual inspection. It is expected that the effectiveness of the high-level product design and development will improve dramatically through the adoption of computer based modeling and simulation. This emerging capability can mitigate the challenges and risks imposed by complex systems by enforcing rigor and precision. Model-based systems engineering (MBSE) is a methodology for designing systems using interconnected computer models. The recent proliferation of MBSE is evidence of its ability to improve the design fidelity and enhance communication among development teams. Existing descriptions of leveraging MBSE for deriving requirements and system design are prevalent. However, very few descriptions of model-based concept development have been presented. This may be due to the lack of MBSE methodologies for performing concept development. Teams that attempt a model-based approach without well defined, structured strategy are often unsuccessful. However, when MBSE is combined with a clear methodology, designs can be more efficiently generated and evaluated. While it may not be feasible to provide a "standard" methodology for concept development, a framework is envisioned that incorporates a variety of methods and techniques. This thesis proposes such a framework and presents an example based on a simulated concept development effort.by Brian London.S.M.in Engineering and Managemen

A model-based systems engineering methodology to make engineering analysis of discrete-event logistics systems more cost-accessible

This dissertation supports human decision-making with a Model-Based Systems Engineering methodology enabling engineering analysis, and in particular Operations Research analysis of discrete-event logistics systems, to be more widely used in a cost-effective and correct manner. A methodology is a collection of related processes, methods, and tools, and the process of interest is posing a question about a system model and then identifying and building answering analysis models. Methods and tools are the novelty of this dissertation, which when applied to the process will enable the dissertation's goal. One method which directly enables the goal is adding automation to analysis model-building. Another method is abstraction, to make explicit a frequently-used bridge to analysis and also expose analysis model-building repetition to justify automation. A third method is formalization, to capture knowledge for reuse and also enable automation without human interpreters. The methodology, which is itself a contribution, also includes two supporting tool contributions. A tool to support the abstraction method is a definition of a token-flow network, an abstract concept which generalizes many aspects of discrete-event logistics systems and underlies many analyses of them. Another tool to support the formalization method is a definition of a well-formed question, the result of an initial study of semantics, categories, and patterns in questions about models which induce engineering analysis. This is more general than queries about models in any specific modeling language, and also more general than queries answerable by navigating through a model and retrieving recorded information. A final contribution follows from investigating tools for the automation method. Analysis model-building is a model-to-model transformation, and languages and tools for model-to-model transformation already exist in Model-Driven Architecture of software. The contribution considers if and how these tools can be re-purposed by contrasting software object-oriented code generation and engineering analysis model-building. It is argued that both use cases share a common transformation paradigm but executed at different relative levels of abstraction, and the argument is supported by showing how several Operations Research analyses can be defined in an object-oriented way across multiple layered instance-of abstraction levels. Enabling Operations Research analysis of discrete-event logistics systems to be more widely used in a cost-effective and correct manner requires considering fundamental questions about what knowledge is required to answer a question about a system, how to formally capture that knowledge, and what that capture enables. Developments here are promising, but provide only limited answers and leave much room for future work.Ph.D

Intégration de la sûreté de fonctionnement dans les processus d'ingénierie système

L'intégration de diverses technologies, notamment celles de l'informatique et l'électronique, fait que les systèmes conçus de nos jours sont de plus en plus complexes. Ils ont des comportements plus élaborés et plus difficiles à prévoir, ont un nombre de constituants en interaction plus important et/ou réalisent des fonctions de plus haut niveau. Parallèlement à cette complexification des systèmes, la compétitivité du marché mondial impose aux développeurs de systèmes des contraintes de coût et de délais de plus en plus strictes. La même course s'opère concernant la qualité des systèmes, notamment lorsque ceux-ci mettent en jeu un risque en vies humaines ou un risque financier important. Ainsi, les développeurs sont contraints d'adopter une approche de conception rigoureuse pour répondre aux exigences du système souhaité et satisfaire les diverses contraintes (coût, délais, qualité, sûreté de fonctionnement,...). Plusieurs démarches méthodologiques visant à guider la conception de système sont définies par l'intermédiaire de normes d'Ingénierie Système. Notre travail s'appuie sur la norme EIA-632, qui est largement employée, en particulier dans les domaines aéronautique et militaire. Il consiste à améliorer les processus d'ingénierie système décrits par l'EIA-632, afin d'intégrer une prise en compte globale et explicite de la sûreté de fonctionnement. En effet, jusqu'à présent la sûreté de fonctionnement était obtenue par la réutilisation de modèles génériques après avoir étudié et développé chaque fonction indépendamment. Il n'y avait donc pas de prise en compte spécifique des risques liés à l'intégration de plusieurs technologies. Pour cette raison, nous proposons de nous intéresser aux exigences de Sûreté de Fonctionnement au niveau global et le plus tôt possible dans la phase de développement, pour ensuite les décliner aux niveaux inférieurs, ceci en s'appuyant sur les processus de la norme EIA-632 que nous étoffons. Nous proposons également une méthode originale de déclinaison d'exigences de sûreté de fonctionnement à base d'arbres de défaillances et d'AMDEC, ainsi qu'un modèle d'information basé sur SysML pour appuyer notre approche. Un exemple issu du monde aéronautique permet d'illustrer nos propositions.The integration of various technologies, including computer and electronics, makes the nowadays designed systems increasingly complex. They have behaviors which are more elaborate and difficult to predict, they have a greater number of components in interaction and/or perform highest level functions. Parallel to this increasing complexity of these systems, the competitive of the global market imposes strong constraints of cost and time to the system developers. Other strong constraints deal with the quality of these systems, especially when they involve human risks or significant financial risks. Thus, developers are forced to adopt a rigorous design approach to meet the desired system requirements and satisfy the various constraints (cost, time, quality, dependability...). Several methodological approaches to guide the system design are defined through system engineering standards. Our work is based on the EIA-632 standard, which is widely used, especially in the aeronautical and military fields. It is to improve the systems engineering process described by the EIA-632, in order to incorporate a global and explicit consideration of dependability. Indeed, till now the dependability was achieved by reusing generic models after having studied and developed independently each function. So there was no specific consideration of the risks associated with the integration of several technologies. For this reason, we propose to concern ourselves with the dependability requirements at the global level and as early as possible in the development phase. Then, these requirements will be decline to lower levels. We based our approach on the processes of the EIA-632 standard that we expand. We also propose an original method for the declination of the dependability requirements based on fault trees and FMEAC, and an information model based on SysML in order to support our approach. An example from the aeronautical field illustrates our proposals

Modelling airport surface safety: a framework for a holistic airport safety management

Airports are complex systems involving the continuous interaction of human operators with the physical infrastructure, technology and procedures to ensure the safe and efficient conduct of flights. From an operational perspective, airport surface operations (i.e. runway and taxiway operations) require the interaction of five main stakeholders (i.e. crew or pilots, air traffic control, airport operator, ground handling and regulator) both to facilitate the ground movement of aircraft and vehicles, and to maintain the surface in a working condition. The complexity of these operations makes the runway and taxiway system vulnerable and presents a risk of failure with the consequent potential for the occurrence of accidents. Therefore, the development and implementation of an effective Safety Management System (SMS) are required to ensure the highest level of safety for surface operations. A SMS is a systematic approach to managing safety based on the four cornerstones of safety policy and objectives, risk management, assurance, and safety promotion. Although the International Civil Aviation Organisation (ICAO) provides the global legislative framework for SMS, the relevant regulations are still to be established at the national level with the consequence that practical guidance on the development and implementation of SMS is rare, and reliable tools to support SMS are lacking. The consequence of this is that the current approach to surface safety management is piecemeal and not integrated. Typically, a single accident and incident type is investigated from the perspective of an individual stakeholder with the consequence that resulting proposals for safety mitigation measures are biased and limited in terms of their impact. In addition, the industry is characterised by non-standardised data collection and investigation practices, insufficient or missing definitions, differing reporting levels, and a lack of a coherent and standardised structure for efficient coding and analysis of safety data. Since these shortcomings are a major barrier to the required holistic and integrated approach to safety management, this thesis addresses the four cornerstones of SMS and recommends major enhancements. In particular, a framework for a holistic airport surface safety management is proposed. The framework comprises the static airport architecture, a process model of surface operations, the determination of causal factors underlying failure modes of these operations, a macroscopic scenario tool and a functional relationship model. Safety data and other data sources feed the framework and a dedicated data pre-processing strategy ensures its validity. Unlike current airport surface safety management practices, the proposed framework assesses the safety of the operations of all relevant actors. Firstly, the airport architecture is modelled and the physical and functional variability of airports defined. Secondly, a process model of surface operations is developed, which captures the tasks of the stakeholders and their interactions with physical airport surface infrastructure. This model serves as a baseline model and guides the further development of the airport SMS. To manage the safety of surface operations, the causes of accidents and incidents must be identified and their impacts understood. To do so, a reference data set combining twelve databases from airlines, airport operators, Air Navigation Service Providers (ANSPs), ground handling companies and regulators is collected. Prior to its analysis, the data is assessed for its quality, and in particular, for its internal validity (i.e. precision), external validity (i.e. accuracy) and in terms of reporting levels. A novel external data validation framework is developed and each database is rated with a data quality index (DQI). In addition, recommendations for reporting systems and safety policies are given. Subsequently, the data is analysed for causal factors across stakeholders and the contribution of the individual actors are highlighted. For example, the analysis shows that the various stakeholders capture different occurrence types and underlying causal factors, often including information that is of potential use for another party. The analysis is complemented by interviews, observations and statistical analysis, and the results are summarised in a new taxonomy. This taxonomy is applicable to all relevant stakeholders and is recommended for operational safety risk management. After the airport surface operations have been modelled and the drivers to safety identified, the results are combined, resulting in a macroscopic scenario tool which supports the management of change (i.e. safety assurance), training and education, and safety communication (i.e. safety promotion) functions of the SMS. Finally, a structured framework to assess the functional relationship between airport surface accidents / incidents and their underlying causal factors is proposed and the system is quantified in terms of safety. Compared to the state-of-the-art safety assessments that are biased and limited in terms of their impact, the holistic approach to surface safety allows modelling the safety impact of each system component, their interactions and the entire airport surface system architecture. The framework for a holistic airport surface safety management developed in this thesis delivers a SMS standard for airports. The standard exceeds international requirements by standardizing the two SMS core functions (safety risk management and safety assurance) and integrating safety-relevant information across all relevant stakeholders. This allows a more effective use of safety information and provides an improved overview on, and prediction of, safety risks and ultimately improves the safety level of airports and their stakeholders. Furthermore, the methodology employed in this thesis is flexible and could be applied to all aspects of aviation SMS and system analysis.Open Acces

AUTOMATED ANALYSIS OF NATURAL-LANGUAGE REQUIREMENTS USING NATURAL LANGUAGE PROCESSING

Natural Language (NL) is arguably the most common vehicle for specifying requirements. This dissertation devises automated assistance for some important tasks that requirements engineers need to perform in order to structure, manage, and elaborate NL requirements in a sound and effective manner. The key enabling technology underlying the work in this dissertation is Natural Language Processing (NLP). All the solutions presented herein have been developed and empirically evaluated in close collaboration with industrial partners. The dissertation addresses four different facets of requirements analysis: • Checking conformance to templates. Requirements templates are an effective tool for improving the structure and quality of NL requirements statements. When templates are used for specifying the requirements, an important quality assurance task is to ensure that the requirements conform to the intended templates. We develop an automated solution for checking the conformance of requirements to templates. • Extraction of glossary terms. Requirements glossaries (dictionaries) improve the understandability of requirements, and mitigate vagueness and ambiguity. We develop an auto- mated solution for supporting requirements analysts in the selection of glossary terms and their related terms. • Extraction of domain models. By providing a precise representation of the main concepts in a software project and the relationships between these concepts, a domain model serves as an important artifact for systematic requirements elaboration. We propose an automated approach for domain model extraction from requirements. The extraction rules in our approach encompass both the rules already described in the literature as well as a number of important extensions developed in this dissertation. • Identifying the impact of requirements changes. Uncontrolled change in requirements presents a major risk to the success of software projects. We address two different dimen- sions of requirements change analysis in this dissertation: First, we develop an automated approach for predicting how a change to one requirement impacts other requirements. Next, we consider the propagation of change from requirements to design. To this end, we develop an automated approach for predicting how the design of a system is impacted by changes made to the requirements