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

Papers by Mara Nikolaidou

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.

International Conference on Software Engineering Advances, Oct 29, 2006

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.

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

Simulation Modelling Practice and Theory, 2016

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.

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.