Showing papers by "John N. Sahalos published in 2018"

Practical Energy Harvesting for Batteryless Ambient Backscatter Sensors

Abstract: This work studies the performance of two methods for providing power to an ultra-low power, ambient backscatter tag, omitting the need for any battery. RF energy harvesting from a dedicated source and energy harvesting from ambient light using a single photodiode are compared. Extensive measurement results from tests conducted under real world conditions are offered for both harvesting methods. It is concluded that for a total cost of under 7 Euros the need for a battery can be eliminated, by using a single photodiode element along with a suitable boost converter. The ultra-low power character of the utilized tag enables the use of multiple harvesting methods and paves the way towards truly battery-less wireless sensor systems.

Game Theoretic Approaches in Mobile Cloud Computing Systems for Big Data Applications: A Systematic Literature Review

Abstract: The constant technological innovations in wireless communications and network technologies as well as the increasing number of smart mobile devices generate an enormous volume of data stemming from a set of user equipments (UEs). Since an exponential growth of data and analytics is witnessed, new technical and application challenges emerge associated with underlying models that exploit cloud computing technologies, such as the Big Data-as-a-Service (BDaaS) or Analytics-as-a-Service (AaaS). In this context, this survey chapter summarizes and establishes to what extend existing research studies have progressed towards applying game theoretic approaches in mobile cloud computing systems for big data applications. We identify and critically evaluate the findings of relevant works addressing this research problem by shedding light on contradictions and gaps in the literature. We therefore propose a cost-benefit model formulation in mobile cloud computing environments and a new game theoretic conceptualization, which accounts for the dynamic storage allocation in cloud systems formulated as a benefit optimization problem. Diverse experimental scenarios are adopted to verify and evaluate the optimality and effectiveness of the developed theory in real-world scenarios.

Elasticity Debt Analytics Exploitation for Green Mobile Cloud Computing: An Equilibrium Model

Abstract: Mobile cloud computing is being accepted as the model for mobile users to ubiquitously access a shared pool of cloud computing resources, data and services on-demand. In this context, elasticity debt analytics can be harnessed as a measure for efficient scheduling of cloud resources and guarantee of quality of service requirements. This paper proposes a novel green-driven, game theoretic approach to minimizing the elasticity debt on mobile cloud-based service level, investigating the case when a task is offloaded, scheduled and executed on a mobile cloud computing system. The decision to offload a mobile device user's task on cloud affects the level of elasticity debt minimization for the provided services. The research problem is formulated as an elasticity debt quantification game, elaborating on an incentive mechanism to: (a) predict elasticity debt and mitigate the risk of service overutilization, (b) achieve scalability as the number of mobile device user requests for cloud resources increases or decreases accordingly, and (c) optimize cloud resource provisioning, parameterizing the current pool of active users per service. The experimental results prove the effectiveness of the equilibrium model, which allocates the mobile device user requests to high elasticity debt-level services and facilitate elasticity debt minimization for greener mobile cloud computing environments.

Characteristic mode analysis of drop-like supershaped patch antenna

Abstract: The Characteristic Mode analysis of a drop-like supershaped patch antenna constitutes the main scope of this project. Supershapes are abstract shapes generated by J. Gielis' Superformula and are used as radiators with wideband properties. The eigenanalysis is performed on the PMCHWT formulated MoM-matrix, derived from the combined field integral equation. The characteristic modes are analyzed via the equivalent magnetic characteristic currents on the printed antenna aperture surface of the cavity-like subdomain of the simulated structure.

Novel three-level architecture for broadband fiber-optic networks

Abstract: This paper presents a novel three-level architecture model for broadband fiber-optic networks. The proposed model exploits the advantages (protocol transparency, reduced cost, infrastructure scalability) of the physical layer in a broadband fiber-optic network. It consists of three layers (central, distribution, access) of hierarchy and six network elements. A bottom-up approach is used to analyze the architecture of the proposed model. Moreover, an integrated system for broadband fiber-optic networks is presented, which is based on the proposed model. Representative examples of fiber-optic metropolitan area networks (MANs) that have been implemented in the region of Central Macedonia, Greece, are illustrated.

Transformation electromagnetics eigen-analysis of perfect electric conductor cavities

Abstract: An alternative variational modal analysis technique is contributed by this study. Although the weak form of the Maxwell equations is employed, instead of using the finite elements technique, the authors utilise entire/global domain vectorial basis functions. In such a case, to assist performance, the basis functions must comply with the boundary conditions. Since in general, this is a difficult task, they adopt the following strategy. They transform the initial convex cavity using coordinate transformation to a canonical one, where a known complete set of vectorial basis functions exist. Then, taking advantage of the form invariance property of the Maxwell equations, in the transformed domain, the authors solve the canonical variational problem and acquire the respective solution to the initial problem by the inverse electromagnetics transformation. Summarising, the contributing concept is to employ a coordinate transformation to a canonical shape employing ‘transformation electromagnetics’ approach as a pre-processing tool to enlarge the scope of a classical electomagnetics (EM) variational eigen-analysis using the canonical shape's vector modes.