Hellenic Telecommunications and Post Commission (Greece)

Several hyperscalers have recently disclosed the occurrence of silent data corruptions (SDCs) in their system fleets, sparking concerns about the severity of known and the existence of unidentified root causes of faults in CPUs. These incidents reveal that CPUs may generate incorrect results due to latent manufacturing defects, variability, marginalities, bugs, and aging. To tackle this, we present Harpocrates, an automated methodology for the generation of short, constrained-random functional test programs that maximize fault detection in target CPU structures and can be employed at different stages of system lifecycle. Harpocrates adopts a hardware-model-in-the-loop approach, iteratively refining the generated test programs via a detailed simulation-based microarchitecture engine that models and grades for multiple fault types. Harpocrates adapts to various program generators, ISAs, microarchitectures, and fault types. Our results on seven important CPU structures show that Harpocrates outperforms open-source test suites in fault detection capability while attaining much shorter generation times.

This paper explores the utilization of alternative measures at the distribution grid level., particularly focusing on local voltage support through reactive power regulation., to identify optimal operating conditions for enhancing Distributed Generation (DG) capacity. To address the challenge posed by the substantial increase in interconnection requests faced by utilities., largely due to the installation of new photovoltaic (PV s) systems on their distribution grids., one viable strategy involves implementing voltage control measures directly by distributed generators. This includes actions such as the absorption of reactive power by DG inverters. A range of possibilities exist., most commonly using an active power dependent reactive power characteristic or using a voltage dependent reactive power characteristic. Different operation scenarios have been examined considering all extreme states of operation of the distribution system. The study is applied for a distribution feeder of a BV IMV substation of the Greek Distribution System with high levels of installed DG capacity. The results of the analysis indicate that the coordinated voltage controls could significantly increase DG hosting capacity without the need of costly grid reinforcements. The technical and economic benefits and challenges associated with such control techniques are discussed and evaluated.

Increasing productivity without jeopardizing the network’s operation, consumers’ experience, and the safety and integrity of procedures, is a major goal for all utilities. Scheduling of work has a direct impact on productivity, especially in the case of utilities that cover a wide geographical area using a limited number of employees. In the case of power utilities, however, scheduling has to consider, apart from the location of issues, the type and technical characteristics of each issue as well as its priority has to be considered in order to produce an optimum schedule. This paper focuses on the impact on productivity of a geospatial ticket management system considering the experience from such a system applied on network studies performed by HEDNO, the Greek Distribution Network Operator, in Patras Area. The term "network studies" is used to describe the study of all expansion and alteration works, ranging from a single Low Voltage (LV) pole installation to major Medium Voltage (MV) network rearrangements/expansion, and includes visits and measurements on the actual location as well as in-door calculations. In Patras Area, the local HEDNO division implemented in 2021-2022 a geospatial ticket managing system, based on available network data and custom Google Maps, aiming to increase its productivity by optimizing the scheduling process. Initial results published in February 2022, showed a significant productivity increase (up to 42%). However, the initial results considered a time span of only one month and thus could easily be misleading. This paper revisits the issue considering a larger time span (more than two years) that should provide more trustworthy results. It also briefly presents the latest updates and improvements made to the system. Results show that the increase in the number of studies and their predicted costs are similar to the initial results, with the increase in productivity being around 41%. In September 2022, HEDNO set the very ambitious goal of significantly increasing the overall production of network studies (more than double in terms of predicted costs) and the use of such a system can provide valuable help towards achieving this goal.

In this paper we confront traditional and novel software architectures regarding their suitability for the development of secure industrial IoT applications. First, we examine the traditional software stack of networked wireless sensor nodes deployed in an industrial scenario. Secondly, we examine edge-based architectures and 5G features standardized for demanding industrial IoT scenarios. Thirdly, we examine the O-RAN architecture and we evaluate this novel model with respect to automated network control and management capabilities. We conclude that the O-RAN model facilitates the development of intelligent data-driven applications and offers an alternative path for the efficient control of IIoT deployments.

This paper presents our study of the presence of the unstable critical point in spontaneous symmetry breaking (SSB) in the framework of Ginzburg–Landau (G-L) free energy. Through a 3D Ising spin lattice simulation, we found a zone of hysteresis where the unstable critical point continued to exist, despite the system having entered the broken symmetry phase. Within the hysteresis zone, the presence of the kink–antikink SSB solitons expands and, therefore, these can be observed. In scalar field theories, such as Higgs fields, the mass of this soliton inside the hysteresis zone could behave as a tachyon mass, namely as an imaginary quantity. Due to the fact that groups Ζ(2) and SU(2) belong to the same universality class, one expects that, in future experiments of ultra-relativistic nuclear collisions, in addition to the expected bosons condensations, structures of tachyon fields could appear.

The unified asymptotic approach is employed herein and yields an analytic description of the input pulse wave, which is required in order to generate a desired waveform-controlled Gaussian pulse envelope chirped harmonic optical wave of arbitrary width at a fixed, arbitrary propagation distance in a linear, dispersive and absorptive dielectric. The dependence of this analytic approach on the input field, medium parameters, and propagation distance is elaborated and its accuracy is verified upon comparison with depicted results of numerical experiments.

ABSTRACT This two-wave study examined whether job burnout relates negatively to employees’ performance in executive functions (i.e., working memory, inhibition capacity, cognitive flexibility, reasoning, problem solving, and planning – assessed through psychometric tests) and positively to everyday cognitive failures (rated by colleagues) over time. Furthermore, based on cognitive reserve and self-regulation theories, we hypothesized that poor cognitive functioning mediates the negative relationship between burnout and job performance (i.e., task and contextual performance), as rated by employees and their close colleagues. The study was conducted among 102 employees and their colleagues, who were followed up over a period of about a year. Structural equation modelling analyses revealed that burnout related to lower performance on working memory and inhibition capacity and to more cognitive failures over time, while reduced cognitive flexibility was associated to higher burnout over time. Moreover, results showed that poor working memory and cognitive failures mediated the negative relationship between burnout and task performance. These findings suggest that burnout prevents optimal utilization of cognitive resources limiting cognitive functioning and consequently, job performance.

An asymptotic analysis of the unified, exact integral representation of the propagated field, is elaborated for the case of chirped Gaussian pulse propagation in a linear Lorentz-type metamaterial medium. The topography of the unified phase function and the dynamics of its saddle points are investigated and their ramifications in the application of the asymptotic methodology are elaborated.

Orbital angular momentum (OAM) mode division multiplexing and encoding have been widely investigated for achieving higher information capacity and performance in both classical and quantum communication systems [1]. A critical component in such systems is an OAM mode sorter that can efficiently sort different OAM modes exp(ilθ) according to the mode index l. To this end, an elegant scheme is to transform the vortex phase exp(ilθ) of OAM modes to a linear phase exp(ilv / β) of tilted plane waves through geometrical transformations, so that they can be separated in the focal plane of a lens. A log-polar transformation was firstly employed [2] and recently a spiral transformation has been proposed to achieve high-resolution OAM mode sorting by the authors [3].

The 5G technology is estimated to transform mobile technology into a General Purpose Technology (GTP), like electricity and the steam engine, since it is expected to be widely adopted and exploited by different vertical industries, such as healthcare, manufacturing, etc., and fundamentally change and progress the global socio-economic conditions. A recent study supported by the European Commission (EC) on the impact of 5G in Europe estimates that in 2025 the introduction of 5G in four verticals (automotive, healthcare, transport and utilities) will create 2.3 million jobs and revenues of C113.1 billion per year. In order to take advantage of these benefits and boost the European leadership in 5G the EC has already adopted several policy and regulatory actions. This paper overviews and discusses these actions, as well as, presents the current spectrum situation for 5G in Europe.