Theo Tryfonas - IEEE Xplore Author Profile

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While existing approaches that integrate IoT and blockchain technologies have demonstrated efficiency, they often exhibit limitations by focusing on a single application scenario. These proposals require specific hardware configurations, resulting reduced adaptability and manageability when transitioning to new application scenarios and updating device configurations. Though, an additional managem...Show More
Machine Learning security is vital for the safe operation of Autonomous Vehicles. When Autonomous Vehicles are connected and cooperating, they form a system of systems that have shared objectives. However, adversarial environments and adversarial vehicles in the system can cause security challenges for the whole system. Current research focuses on the Machine Learning security challenges from the ...Show More
Today’s MBSE tools and environments are highly varied and therefore present a challenge for organizations looking to implement MBSE. Furthermore, while MBSE environments are highly capable of supporting the description of design baselines, the current capabilities within these environments could be further refined for exploring alternative designs. As a result it is important to gain an understand...Show More
The definition of complexity is contentious. The lack of a univocal definition for complexity is leading to a cacophony of different views and lexicons, limiting the collective ability to handle complexity effectively. This article aims to resolve this impasse by identifying or developing a useful and acceptable definition of complexity by focusing on how this term is used in practice, and hence d...Show More
Transactive Energy Markets (TEM) have the potential to reduce wasted energy, increase the utilisation of renewable energy resources and enable independence in the energy sector. Blockchain has been utilised in TEMs in the literature aiming to acquire transparency, security and trustless operations. Though public blockhain enables leveraged transparency and fairness, the majority of proposals sugge...Show More
E-scooter sharing platforms (ESPs) offer fast, affordable and flexible urban mobility solutions, with numerous benefits such as reducing traffic congestion, air pollution and carbon emissions. However, the long-term sustainability of the platform could be challenged by the threats and risks it faces because these can negatively impact the system and its users. The potential consequences may includ...Show More
Existing proposals that merge IoT with blockchain technologies have been efficient but often limited to a single application scenario. They require specific hardware setups, thus in case of switching to a new application scenario, they may become ineffective and require a new hardware setup. In this paper, we present a new blockchain-based architecture for IoT environments that addresses one of th...Show More
Model Based Systems Engineering (MBSE) is an interesting alternative to traditional systems engineering methods. Instead of using electronic documents to record system information, MBSE uses a unified and coherent system model. Trade-offs are a major element of a space systems engineer's role in early system design. This can be a particularly challenging process in the domain of spacecraft, as the...Show More
RPL-based IoT networks are vulnerable to routing attacks as well as flooding attacks. Developing security countermeasures requires knowledge of possible attacks, their timing, and combinations. Most implementations of RPL related attacks only consider individual attacks triggered when their simulation starts. Furthermore, nodes which to be compromised are preselected before a simulation starts and...Show More
In this paper, an approach referred to as IoTsecM is proposed. This proposal is a UML/SysML extension for security requirements modeling within the analysis stage in a waterfall development life cycle in a Model-Based Systems Engineering Approach. IoTsecM allows the security requirements representation in two very well-known modeling languages, UML and SysML. With the utilization of this extension...Show More
The inability to handle rising complexity effectively is often the cause of project, organizational, enterprise, and even societal collapse. A tractable set of heuristics for handling complexity that can mitigate this risk is consequently highly sought. However, conventional experience-based approaches for identifying complexity handling advice tend to lead to informed but complicated constructs t...Show More
Model-based systems engineering (MBSE) represents a move away from the traditional approach of document-based systems engineering (DBSE), and is used to promote consistency, communication, clarity, and maintainability within systems engineering projects. MBSE offers approaches that can address issues associated with cost, complexity, and safety. One way that this can be achieved is by performing e...Show More
Model-Based Systems Engineering (MBSE) represents a move away from the traditional approach of Document-Based Systems Engineering (DBSE), and is used to promote consistency, communication, clarity and maintainability within systems engineering projects. In previous work, industry focus groups have indicated that one way this can be achieved is by performing early functional validation of elements ...Show More
The Internet of Things (IoT) is growing rapidly and official reports suggest that soon it will become one of the key technologies of the Internet infrastructure. Cloud services are already integrated with IoT, providing solutions for a large number of applications. Various Cloud IoT platforms are available for IoT users, both as open source and commercial solutions. One of the important features o...Show More
Asthma is a chronic disease that cannot be cured but however it can be managed. There are different ways for Asthma management and the Asthma Action Plan is one of the self-management methods used for managing and monitoring a patient's condition. In this paper, we use an ontology-based method to identify and classify Asthma Action Plan terminologies and integrate respective models with demographi...Show More
The need to handle complexity has shifted from a nice to have to ensure project and organizational success, to a necessity. One approach to improve organizational performance in handling complexity is to observe what has been successful with similar complex activities in the past. Consequently, suitable Complexity Categorization Frameworks are required. This paper seeks to identify appropriate fra...Show More
This paper details a concept model for proactive competence, that provides a bridge between Situational Awareness (SA) and Operational Agility (OA) models. The model addresses a gap within the literature for an end-to-end view of the functions required for effective awareness and proactive action. A set of common concepts from different SA-domains are defined to provide a consistent approach and i...Show More
Model-Based Systems Engineering (MBSE) represents a move away from the traditional approach of Document-Based Systems Engineering (DBSE), and is used to promote consistency, communication, clarity and maintainability within systems engineering projects. MBSE offers approaches that can address issues associated with cost, complexity and safety. Focus groups with Airbus spacecraft functional avionic...Show More
The successful deployment of safe and trustworthy Connected and Autonomous Vehicles (CAVs) will highly depend on the ability to devise robust and effective security solutions to resist sophisticated cyber attacks and patch up critical vulnerabilities. Pseudonym Public Key Infrastructure (PPKI) is a promising approach to secure vehicular networks as well as ensure data and location privacy, conceal...Show More
The Internet of things (IoT) is the natural evolution of the current Internet. As such, IoT systems do not just handle critical information as passwords, identities, personal information, routines, etc., but they also are able to control a whole variety of systems, for instance a robotic network in the automotive industry, autonomous cars networks, human health care and many systems in other domai...Show More
Advance clustering techniques have been widely used in Wireless Sensor Networks (WSNs) since they can potentially reduce latency, improve scheduling, decrease end-to-end delay and optimise energy consumption within a dense network topology. In this paper, we present a novel clustering algorithm for high density IEEE 802.15.4-2015 Time-Slotted Channel Hopping (TSCH). In particular, the proposed met...Show More
Delivery complexity is recognized universally as continually increasing; suggesting that Complexity or Difficulty Assessment Tools (CATs/DATs) are even more critical for ensuring that the right delivery approaches are selected. However, these tools appear immature, with significant diversity between the tools. Consequently, which tool to use, or type of tool to develop, becomes a critical decision...Show More
The confidentiality of communications in the Internet of Things (IoT) is critical, with cryptography currently being the most widely employed method of ensuring it. Establishing cryptographically secure communication links between two transceivers requires the pre-agreement on some key, unknown to an external attacker. In recent years there has been growing attention in techniques that generate a ...Show More
The Semantic Web (SW) is a significant advancement in the field of Internet technologies and an uncharted territory as far as security is concerned. In this paper, we investigate and assess the impact of known attacks of SPARQL/SPARUL injections on Semantic Web applications developed in PHP. We highlight future challenges of developing robust Semantic Web applications using PHP. Our results demons...Show More
With the ubiquity of sensing technologies in our personal spaces, the protection of our privacy and the confidentiality of sensitive data becomes a major concern. In this letter, we focus on wearable embedded systems that communicate data periodically over the wireless medium. In this context, we demonstrate that private information about the physical activity levels of the wearer can leak to an e...Show More