Experimental evaluation of a CPU Live Migration on ARM based Bare metal Instances

The advent of 5G and the adoption of digitalization in all areas of industry has resulted in the exponential growth of the Internet of Things (IoTs) devices, increasing the flow of data that travels back and forth to a centralized Cloud data centre for storage, processing, and analysis. This in turn puts pressure on the intermediate edge and core network infrastructure as traditional Cloud Computing is not ready to support this massive amount and diversity of devices and data. This need for faster processing, low latency and higher network consistency makes a case for Edge Computing solutions. However, applying Edge Computing as a solution to overcome the network performance limitations that exist on an “IoT to Cloud” architecture while continuing to use Virtualization technology for system utilization is a bit of an oxymoron. Virtualization increases performance overheads, while sharing network resources among users and applications creates further bandwidth limitations and latency since communications are still served through the same physical network interfaces. The demand for network and system consistency, finer security and privacy has led to the deployment of Bare metal instances. Bare metal instances are nothing more than traditional servers that lack the virtualization layer offering native performance to the user. Furthermore, the rise of the ARM processors and the introduction of cheap low power architectures targeted to the Edge introduce a compelling new candidate platform especially on Bare metal instances. Live migration is a valuable tool for increasing applications and users’ mobility, service availability offering workload balancing and fault tolerance. However, live migration is tied to the existence of a virtualization layer therefore implementing a live migration process on Bare metal instances is very challenging. To the best of our knowledge, there is no existing proposal for a Bare metal live migration scheme on ARM based systems. Therefore, this thesis presents a novel design, implementation, and evaluation of an ARM based live migration scheme for Bare metal instances suitable for modern EdgeComputing Micro Data Centres. Our experimental evaluation confirms the effectiveness of our novel design as well as highlighting the importance on identifying the number of registers that describe and are critical for the reconstruction of the CPU state at the destination

Design of a High-Q Diamond-Loaded Cavity for a Third-Harmonic Subterahertz Gyrotron Driven by a Low-Power Electron Beam

A continuous-wave (CW) high-harmonic gyrotron driven by a low-power electron beam is a compact radiation source demanded by terahertz applications. Its physical feasibility, however, is hampered by ohmic losses and mode competition in the gyrotron cavity. An ultralow-loss diamond loading of the cavity can give a clue to this problem. This article is concerned with theoretical aspects of mode selection and design for a gyrotron cavity loaded with coaxial rod made of chemical vapor deposition (CVD) diamond. As an example, the design of a high-Q diamond-loaded cavity for a third-harmonic 658-GHz gyrotron powered by a 0.1-A, 15-kV electron beam is presented. It is shown that the designed cavity enables the gyrotron to produce up to 116-W output power in a single oscillating mode

Improved Mode Selection in Coaxial Cavities for Subterahertz Second-Harmonic Gyrotrons

A coaxial metal rod with partial dielectric coating is considered as a means for efficient suppression of all volume competing modes in cavities for second-harmonic gyrotrons operated in whispering gallery modes. The rod radius is selected small enough to have only a slight effect on operating mode, which therefore remains insensitive to fabrication tolerances and a misalignment of the coaxial insert. By contrast, for the competing modes such a rod is shown to reduce the effective cavity length, thereby greatly increasing the starting currents. Such a method of mode selection is demonstrated to be more versatile, when compared to that provided by a tapered coaxial conductor. The advantage of a dielectric-coated coaxial insert is illustrated by the example of a cavity for a 100-kW 300-GHz pulsed gyrotron operated in the second-harmonic mode

Public Access Defibrillation

The single most important cause of death in the adult population of the industrialized word is sudden cardiac death (SCD) due to coronary artery disease (CAD). In a population based study the overall yearly incidence of SCD was 1 per 1000 persons aged20 to 75 years of age. Overall 21% of deaths in men and 15% in women were sudden and unexpected. The vast majority of out of hospital deaths occur at home and about 15% in a public place or on the street. Forty percent of SCDs were unwitnessed. Themajority of patients have ventricular tachycardia or fibrillation as the first recorded rhythm after patients collapse

Experimental Testing of the European TH1509U 170-GHz 1-MW CW Industrial Gyrotron – Long Pulse Operation

The upgraded European 1-MW, 170-GHz continuous wave (CW) industrial prototype gyrotron (TH1509U) for electron cyclotron resonance heating and current drive in ITER was tested at the Karlsruhe Institute of Technology (KIT). In this work, we report on the major achievements during the experimental campaigns that took place intermittently between October 2020 and July 2021. The upgraded gyrotron clearly surpassed the performance of the previous TH1509 tube. In particular, TH1509U delivered (i) 0.9 MW in 180 s pulses (maximum possible pulse length with the KIT test stand) and (ii) more than 1 MW at a pulse length limited to 40 s, due to an unforeseen problem with the test stand cooling circuit at that time. In addition, it was possible to also demonstrate gyrotron operation at (iii) 0.5 MW in 1600 s pulses. The experiments will be continued at the FALCON test stand at the École Polytechnique Fédérale de Lausanne (EPFL)

An inerter-equipped vibrating barrier for non-invasive motion control of seismically excited structures

The Vibrating Barrier (ViBa) is a large-scale oscillating mass-spring-damper unit contained in the ground and tuned to mitigate the motion of surrounding structures under earthquakeinduced ground shaking, without being directly in contact to them, through a structure-soilstructure interaction mechanism. Previous research showed that ViBa achieves significant seismic structural response reductions but, in doing so, it requires excessive vibrating mass, equal to the mass of the structure that aims to control or more, which hinders its practical applicability. This paper considers coupling ViBa with a grounded inerter acting as a mass amplifier to reduce ViBa mass/weight in suppressing seismically induced structural response. Attention is focused on structures amenable to modelling as single-degree-of freedom (SDOF) damped oscillators by establishing equations of motion of a 5-DOF dynamical system of a grounded inerter-equipped ViBa (IViBa) fused with a SDOF structure and accounting for soil structure interaction (SSI) effects due to soil compliance. Optimal closed-form H∞ and numerical H2 IViBa tuning are addressed minimizing the response of SDOF structure subject to harmonic resonant and to broadband/white base excitation, respectively. Numerical results pertaining to a small-scale physical ViBa prototype specimen are furnished quantifying the trade-off between IViBa mass and inertance considering non-rigid/compliant inerter-to-ground connectivity. Monotonic IViBa mass/weight reduction trend is found for fixed targeted structural performance under white stationary as well as colored non-stationary seismic excitation for increasing inertance and for sufficiently rigid inerter-to-ground connection. It is concluded that careful engineering design of the inerter-to-ground connection minimizing compliance is most critical in fully exploiting the beneficial effects of grounded inerter for mass/weight IViBa reduction facilitating, thus, its practical implementation

The ECRH-Power Upgrade at the Wendelstein 7-X Stellarator

The existing ECRH system at W7-X consists of 10 gyrotrons, with output power levels ranging from 0.6 MW up to 1.0 MW each at a frequency of 140 GHz, quasi-optical transmission lines and microwave launchers at the plasma vessel. Compared to other large fusion experiments, W7-X has a relatively low power-to-volume ratio. However high heating power is particularly necessary for achieving high plasma beta values, where the improved confinement of fast ions, one of the optimization criteria of W7-X, can be examined. It is therefore necessary to expand the ECRH systems in several consecutive steps. It is planned to increase the number of gyrotron positions from 10 to 12 and at the same time to evolve the gyrotron output power in several development steps from 1 MW to nominal 1.5 MW and, finally, up to 2 MW. At the same time, the transmission lines will also be upgraded for 2 MW operation. A special effort is also made to improve the reliability of the system by the fast control system