Mara Nikolaidou - Profile on Academia.edu (original) (raw)

Papers by Mara Nikolaidou

Leveraging Quality of Service and Cost in Cyber-Physical Systems Design

Lecture Notes in Computer Science, 2019

Cyber-Physical Systems (CPSs) comprise multiple cyberparts, physical processes, and human partici... more Cyber-Physical Systems (CPSs) comprise multiple cyberparts, physical processes, and human participants (end-users) that affect them, and vice versa. During the design of such systems, it is critical for the designer to take into account the end-user-perceived quality of provided services, as well as their cost, and integrate them into the CPSs; striking a satisfactory balance between quality and affordability is critical to system acceptance. In this work, we propose a model-based approach, using the Systems Modeling Language (SysML), to explore system design, encapsulating Quality of Service (QoS) and cost aspects, as system requirements, into a core model. Via this approach, the designer can define the system structure, configure it, measure and evaluate the quality, while analyzing cost, and find the best solution(s) for a correct design. As a use case, this approach is applied to a healthcare CPS, namely the Remote Elderly Monitoring System (REMS). In that context, managing REMS QoS and cost requirements, can contribute to an effective system design and implementation, enhancing the end-user satisfaction.

Model-based system design is served by a single, multi-layered model supporting all design activi... more Model-based system design is served by a single, multi-layered model supporting all design activities, in different levels of detail. SysML is a modeling language, endorsed by OMG, for system engineering, which aims at defining such models for system design. It provides discrete diagrams to describe system structure and components, to explore allocation policies crucial for system design, and to identify design requirements. In this chapter, SysML is used for the model-based design of enterprise information system architecture, supporting a systemic view of such systems, where software and hardware entities are treated as system components composed to create the system architecture. SysML extensions to facilitate the effective description of non-functional requirements, especially quantitative ones, and their verification are presented. The integration of evaluation parameters and results into a discrete SysML diagram enhances the requirement verification process,

Distributed system configuration consists of distributed application component placement and unde... more Distributed system configuration consists of distributed application component placement and underlying network design, thus is a complex process dealing with interrelated issues. A four-stage methodology has been proposed in order to effectively explore configuration problems. A common metamodel for distributed system representation in all configuration stages is thus required, so that unclear dependencies between discrete stages can be easily identified. This model should also be easily adopted by autonomous software tools used for the automation of discrete configuration stages and for the efficient development of system specifications by designers. We propose such a metamodel using UML 2.0. More specifically, we introduce a UML 2.0 profile facilitating distributed system configuration process. In this profile, different UML 2.0 diagrams are integrated and properly extended, in order to model all aspects of the distributed system configuration process. Stereotypes proved to provide an efficient extension mechanism as no metamodel extensions were needed. This profile can also be used within the Rational Modeler platform.

International Conference on Software Engineering Advances, Oct 29, 2006

Enterprise Information Systems can be described according to the Open Distributed Processing Refe... more Enterprise Information Systems can be described according to the Open Distributed Processing Reference Model (RM-ODP), where five different viewpoints are specified analyzing various aspects of the system. Configuration issues are explored in the Engineering Viewpoint of RM-ODP. In practice, configuration issues are explored in discrete stages, supported by autonomous software tools, each of which adopts its own metamodel for system representation. We propose a platform independent framework, which focuses on the Engineering Viewpoint of Enterprise Information Systems managing application configuration and network design issues independently of application development progress. In order to apply this framework using existing tools, model exchangeability and tool coordination must be supported by standard, open methods. Thus, a common metamodel is proposed to generate enterprise information system models, which are stored in XML. A UML 2.0 profile is defined to visualize these models, facilitate the designer to interact with them and coordinate specific tool invocation.

Proceedings, Oct 1, 2006

This paper presents a conceptual framework for service modelling. This framework provides a conce... more This paper presents a conceptual framework for service modelling. This framework provides a conceptual basis for the modelling and reasoning about services, and the operations, such as composition and discovery, that are performed on them at design and run-time. In particular, the framework should facilitate the use of different service description languages tailored to different service aspects, such as the behaviour of a service and the information it manipulates, or design tasks, such as modelling, analysis and implementation. The idea is that models produced by these languages can be mapped onto a single, common conceptual framework, thereby facilitating one to relate these models, e.g., to verify consistency or conformance. Therefore, a requirement on the framework is to capture all elementary and generic service properties that are relevant during the service development process. We capture these properties by analysing existing service definitions and from earlier experience.

A Model-Based Approach for the Design of Cyber-Physical Human Systems Emphasizing Human Concerns

A Cyber-Physical Human System (CPHS) comprises software, hardware and the human, allowing interac... more A Cyber-Physical Human System (CPHS) comprises software, hardware and the human, allowing interactions between them. While such systems become more complex, it is crucial to consider the human factor during their design, addressing human concerns. In previous work, the authors attempted to translate human concerns into criticalities, e.g., design requirements depicting human concerns, restricting CPHS usage. Here, an approach is proposed, aiming to facilitate the designer of CPHSs to integrate criticalities into the design process. This enables a more efficient design. For this purpose, we introduce a model-based approach adopting Object Management Group (OMG) standards, such as Business Process Model and Notation (BPMN), and Systems Modeling Language (SysML), to explore CPHS design and identify discrete views, representing both human and system aspects. Moreover, we explore the applicability of the proposed approach in the design of a Remote Elderly Monitoring System (REMS), where it is essential for the human to become part of the system wearing medical sensors. The identification of human criticalities during REMS design enabled the designer to evaluate different configurations considering human concerns.

Exploring LoS in railway transportation systems using SysML

2018 Annual IEEE International Systems Conference (SysCon), 2018

Railway Transportation Systems (RTSs) are systems of high complexity consisting of other systems.... more Railway Transportation Systems (RTSs) are systems of high complexity consisting of other systems. Thus, they may be studied as Systems-of-Systems (SoS) using the Systems Modeling Language (SysML). Since their purpose is to provide transportation services that have a critical role in urban societies and affect millions of users, they have to be precisely evaluated, focusing on their adequacy to deliver the expected service quality. In the case of RTSs, service quality is expressed by Level of Service (LoS) indicators related to the passenger's experience within RTS components, such as stations and trains. Such indicators express, for example, space and time restrictions, and are standardized in international bodies. In this paper, an approach, integrating LoS concepts in ModelBased Systems Engineering (MBSE), is proposed, enabling the description and verification of LoS requirements for RTS SysML models. Exploiting SysML, a RTS model can be generated, populated with basic transportation entities and specific LoS requirements associated to them. Requirements are described in a simple, abstract fashion by the RTS engineer, while more specific requirements are automatically generated and associated with basic RTS components. Furthermore, verification of RTS LoS is facilitated, helping the system designer to assess alternative RTS operation scenarios. In this context, a case study discussing the Athens Metro System is briefly examined.

Advances in Computer Science : an International Journal, 2016

Systems Modeling Language (SysML) is a standard proposed by the OMG for systems-of-systems (SoS) ... more Systems Modeling Language (SysML) is a standard proposed by the OMG for systems-of-systems (SoS) modeling and engineering. To this end, it provides the means to depict SoS components and their behavior in a hierarchical, multi-layer fashion, facilitating alternative engineering activities, such as system design. To explore the performance of SysML, simulation is one of the preferred methods. There are many efforts targeting simulation code generation from SysML models. Numerous simulation methodologies and tools are employed, while different SysML diagrams are utilized. Nevertheless, this process is not standardized, although most of current approaches tend to follow the same steps, even if they employ different tools. The scope of this paper is to provide a comprehensive understanding of the similarities and differences of existing approaches and identify current challenges in fully automating SysML models simulation process.

Systems Engineering, 2019

The concept of Level of Service (LoS) is not inherently supported by Systems Modeling Language (S... more The concept of Level of Service (LoS) is not inherently supported by Systems Modeling Language (SysML), the standard modeling notation for model‐based systems engineering. This paper describes and demonstrates an approach that enhances SysML to enable LoS modeling and evaluation. A SysML profile enables the definition and visual verification of LoS during system operation, via LoS specific requirements, inside the system model, and the association of these requirements with specific system components. Hence, static and dynamic aspects of the system model are used for the LoS verification, while specific design alternatives are automatically proposed, in case the desired LoS is not achieved. As a proof of concept, the proposed approach was applied to explore passenger comfort, a key LoS metric, indicating space available to passenger in Railway Transportation Systems (RTSs). A specific case study on passenger comfort for the Athens Metro was conducted to derive insights regarding the...

2016 IEEE International Conference on Systems, Man, and Cybernetics (SMC), 2016

Model-based Systems Engineering (MBSE) promises efficient and effective systems development, by p... more Model-based Systems Engineering (MBSE) promises efficient and effective systems development, by providing integrated system model views and streamlining the transition between different development activities. For instance, system testing with simulation should be provided as a simple facility for the performance evaluation of complex systems. Transportation systems are complex and their behavior is determined by dynamic factors. However, research efforts define simulation models for transportation systems, using custom or simulation-specific notation. Additionally, model-based approaches for transportation systems emphasize peripheral issues, such as safety conditions and environmental impact. In this work, a framework that enables seamless performance evaluation of Railway Transportation System (RTS) models via simulation is proposed. The de facto standard for MBSE modeling, Systems Modeling Language (SysML), is selected as the modeling infrastructure, while other standards, like Query/View/-Transformation (QVT), are used for the generation of executable simulation models. The latter can be simulated in Discrete Event System Specification (DEVS) simulators and the simulation results are returned in the RTS SysML model. Additionally, the application of the framework in the public RTS of Athens and the obtained simulation results are presented.

Simulation Modelling Practice and Theory, 2016

Systems Modeling Language (SysML) is used as the modeling infrastructure in systems engineering, ... more Systems Modeling Language (SysML) is used as the modeling infrastructure in systems engineering, especially for complex systems design, independently of the system domain. Simulation is a common method to perform system model verification, during the systems development process. However, simulation code generation and execution is not integrated within the system design activity, as it is facilitated by SysML. It is either conducted as an external activity, after system design, or it affects the system design environment and practices, according to specific simulators requirements. This paper presents how existing, simulation-agnostic SysML models from the domain of Enterprise Information System (EISs), can be transformed to executable simulation code and in addition how the simulation results can be incorporated into the source SysML model through the exploitation of Model Driven Architecture (MDA) principles and techniques. To this end, several tools and technologies are utilized, while the verification process is triggered and finalized via the system modeling environment. Adoption of MDA provides a solid, high-level infrastructure and tool availability to the proposed approach.

Integrating cost analysis in the cloud: A SoS approach

2015 11th International Conference on Innovations in Information Technology (IIT), 2015

Cloud computing has succeeded in transforming the ICT industry, making software and hardware serv... more Cloud computing has succeeded in transforming the ICT industry, making software and hardware services even more accessible to businesses and establishing an environment for rapid innovation. Since cloud computing is an innovative business model, whose deployment is accompanied by huge investments, a thorough, multilevel cost analysis of provided services is vital. Such an analysis should focus, among others, on demand forecasting for computational resources and financial assessment of cloud computing investments, estimating crucial economic parameters, such as Net Present Value (NPV), Return of Investment (ROI) and Total Cost of Ownership (TCO). Into this context, a model-driven techno-economic approach is introduced in this paper targeting the estimation of economic parameters of cloud service deployment, which is able to assist decision support procedures for cloud users, cloud providers and cloud brokers. SysML is adopted as a modeling language for describing cloud architectures as system-of-systems (SoS), emphasizing cost properties. As an example, the Total Cost of Ownership (TCO) for cloud infrastructure and services is explored. TCO properties are incorporated into SysML cloud models, while cloud providers are facilitated in computing TCO.

A Holistic Approach in Enterprise Business Process Modeling

ABSTRACT

Simulating SysML models: Overview and challenges

2015 10th System of Systems Engineering Conference (SoSE), 2015

SysML language, proposed by OMG, is a commonly accepted standard to model and study systems-of-sy... more SysML language, proposed by OMG, is a commonly accepted standard to model and study systems-of-systems (SoS). It provides the means to depict SoS components and their behavior in a multi-layer fashion and explore alterative architectures for their design. To validate SysML models in terms of performance criteria, simulation is usually the preferred method employed. To this end, different SysML diagrams are utilized, while numerous simulation methodologies and tools are employed. There are many efforts targeting simulation code generation from SysML models. Model-based system engineering concepts are adopted in most of them to generate simulation models from SysML models. Nevertheless, this process is not standardized, although most of current approaches tend to follow the same steps, even if they employ different tools. The scope of this paper is to provide a comprehensive understanding of the similarities and differences of existing approaches and identify current challenges in fully automating SysML models simulation process.

2015 IEEE 9th International Conference on Research Challenges in Information Science (RCIS), 2015

A model-based approach for the design of enterprise information system architecture is proposed i... more A model-based approach for the design of enterprise information system architecture is proposed in this paper. It facilitates the progressive refinement of system architecture based on a well-defined model and the systematic manipulation of information exchange with other methodologies addressing related engineering activities (for example software design). The Systems Modeling Language (SysML) is used for the representation of the proposed system model. The SysML profile, constructed for that purpose, is presented. The experience obtained when applying the proposed SysML profile in the renovation of a large-scale enterprise information system is also briefly discussed.

Infusing agility in business processes through an event-centric approach

International Journal of Business Information Systems, 2010

Proceedings of the 27th Annual ACM Symposium on Applied Computing, 2012

Model-driven system design is facilitated by SysML language, which provides distinct diagrams to ... more Model-driven system design is facilitated by SysML language, which provides distinct diagrams to describe system structure and components, explore allocation policies and identify system requirements. While non-functional requirements play a significant role in system design, their are not effectively supported by SysML. This paper emphasizes on a SysML extension to facilitate the effective description and verification of non-functional quantitative requirements. The introduction of a distinct SysML diagram to explore evaluation results enhances requirement verification capabilities, while the visualization of verification process helps system engineers to explore design decisions and properly adjust system design. Based on the proposed SysML extension, a profile for Enterprise Information System architecture design was developed. To demonstrate the potential of the proposed approach, the description and verification of software performance requirements using this profile are discussed, as an example.

Integrating simulation capabilities into SysML for enterprise information system design

2014 9th International Conference on System of Systems Engineering (SOSE), 2014

2014 IEEE International Systems Conference Proceedings, 2014

Systems Modeling Language (SysML) is used to define hierarchical system models in model-based eng... more Systems Modeling Language (SysML) is used to define hierarchical system models in model-based engineering (MBE). Although SysML may effectively serve the description of complex systems, it can not effectively support all modelbased engineering activities. For example, system validation is usually performed via simulation. In this case, SysML system models should be transformed to domain-specific models, e.g. executable simulation models suitable for specific simulation tools. This paper identifies the key issues for efficient SysML model simulation, utilizing Model Driven Architecture (MDA) concepts. The generation of executable simulation code from SysML system models is considered as a model transformation from the SysML meta-model to the simulation meta-model. Since SysML meta-model is defined using Meta-Object Facility (MOF), the definition of MOF simulation meta-models and the utilization of the Query/View/Transformation (QVT) language for model transformations are analytically discussed. The presented approach is not restricted in a specific simulation framework or type. However, in this paper, the experience obtained from a case study on discrete event simulation is evaluated and the conditions that favor the selection of specific simulation frameworks are identified.

International Conference on Software Engineering Advances (ICSEA 2007), 2007

Extension mechanisms offered by UML 2.0 are often explored in order to define UML profiles that s... more Extension mechanisms offered by UML 2.0 are often explored in order to define UML profiles that serve specific modeling purposes. These UML 2.0 profiles should be effectively accommodated by standard UML-based modeling tools, which provide the means for applying them in practice. Almost every UML 2.0 modeling tool supports the definition of stereotypes and the description of constraints in Object Constraint Language. However, implementing a profile in practice often entails the development of additional functionality. This requirement mainly stems from the fact that when dealing with complex models it is more efficient for end-users to help them enforce a constraint rather than notify them when it is broken. Such issues, encountered when developing a UML 2.0 profile for enterprise information systems engineering using Rational Software Modeler as a standard UML 2.0 modeling tool, are discussed in the paper.