Quantum key distribution (QKD) is an innovative technology that exploits the laws of quantum mechanics to generate and distribute unconditionally secure shared key for use in cryptographic applications. However, QKD is a relatively nascent technology where real-world system implementations differ significantly from their ideal theoretical representations. In this paper, we introduce a modeling framework built upon the OMNeT++ discrete event simulation framework to study the impact of implementation nonidealities on QKD system performance and security. Specifically, we demonstrate the capability to study the device imperfections and practical engineering limitations through the modeling and simulation of a polarization-based, prepare and measure BB84 QKD reference architecture. The reference architecture allows users to model and study complex interactions between physical phenomenon and system-level behaviors representative of real-world design and implementation tradeoffs. Our results demonstrate the flexibility of the framework to simulate and evaluate current, future, and notional QKD protocols and components.

Gaze-control enables people to control a computer by using eye-gaze to select items on screen. Gazecontrol is a necessity for people who have lost all motor control of their body and only have control over eye movements. In addition, gaze-control can be the quickest and least tiring option for a far broader group of people with varying disabilities. This paper reports findings from gaze-control user trials involving users from both groups: people who are totally paralyzed, as well as people with a wide range of complex disabilities. The trials conducted involved four different centres supporting people with disabilities in three different European countries. Several gaze-control systems were trialled by a large number of users with varying needs and abilities. The perceived benefits of gaze-control are described, and recommendations for successful assessment and implementation of gaze-control are provided.

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In this paper, we present modeling a Quantum Key Distribution (QKD) system with its components using the Discrete Event System Specification (DEVS) formalism. The DEVS formalism assures the developed component models are composable and exhibit well-defined temporal behavior independent of the simulation environment. These attributes enable users to assemble a valid simulation using any collection of compatible components to represent complete QKD system architectures. To illustrate the approach, we introduce a prototypical ''prepare and measure'' QKD system, decompose one of its subsystems, and present the detailed modeling of the subsystem using the DEVS formalism. The developed models are provably composable and exhibit behavior suitable for the intended analytic purpose, thus improving the validity of the simulation. Finally, we examine issues identified during the verification of the conceptual DEVS model and discuss the impact of these findings on implementing a hybrid QKD simulation framework.