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The GRANDMA network in preparation for the fourth gravitational-wave observing run

Jean-Paul Richard Kneib, Xiao Wang, Jieping Zhu

GRANDMA is a world-wide collaboration with the primary scientific goal of studying gravitational-wave sources, discovering their electromagnetic counterparts and characterizing their emission. GRANDMA involves astronomers, astrophysicists, gravitational-wave physicists, and theorists. GRANDMA is now a truly global network of telescopes, with (so far) 30 telescopes in both hemispheres. It incorporates a citizen science programme (Kilonova-Catcher) which constitutes an opportunity to spread the interest in time-domain astronomy. The telescope network is an heterogeneous set of already-existing observing facilities that operate coordinated as a single observatory. Within the network there are wide-field imagers that can observe large areas of the sky to search for optical counterparts, narrow-field instruments that do targeted searches within a predefined list of host-galaxy candidates, and larger telescopes that are devoted to characterization and follow-up of the identified counterparts. Here we present an overview of GRANDMA after the third observing run of the LIGO/VIRGO gravitational-wave observatories in 2019 - 2020 and its ongoing preparation for the forthcoming fourth observational campaign (O4). Additionally, we review the potential of GRANDMA for the discovery and follow-up of other types of astronomical transients.

SPIE-INT SOC OPTICAL ENGINEERING2022

Differentiated consistency for worldwide gossips

Davide Frey

Eventual consistency is a consistency model that favors liveness over safety. It is often used in large-scale distributed systems where models ensuring a stronger safety incur performance that are too low to be deemed practical. Eventual consistency tends to be uniformly applied within a system, but we argue a demand exists for differentiated eventual consistency, e.g. in blockchain systems. We propose UPS to address this demand. UPS is a novel consistency mechanism that works in pair with our novel two-phase epidemic broadcast protocol GPS to offer differentiated eventual consistency and delivery speed. We propose two complementary analyses of the broadcast protocol: a continuous analysis and a discrete analysis based on compartmental models used in epidemiology. Additionally, we propose the formal definition of a scalable consistency metric to measure the consistency trade-off at runtime. We evaluate UPS in two simulated worldwide settings: a one-million-node network and a network emulating that of the Ethereum blockchain. In both settings, UPS reduces inconsistencies experienced by a majority of the nodes and reduces the average message latency for the remaining nodes.

2022

Actuator, valve actuator unit and valve

Fabio Beco Albuquerque, Herbert Shea

An actuator (22) comprises at least one actuator body (32) of dielectric elastomeric material and two electrodes (34, 36) being attached to opposite surfaces of the actuator body (32), respectively. At least one of the actuator body (32) and at least one of the electrodes (34, 36) is at least partly covered at its outer side with a protective layer (38a, 38b) of polymer material, wherein a mechanical stiffness of the protective layer (38a, 38b) is at least three times lower than a mechanical stiffness of the actuator body (32). Moreover, a valve actuator unit comprises such an actuator (22) and a housing, wherein the actuator (22) is arranged within the housing and the remainder of the housing is filled with a gas. Additionally, a valve comprises such a valve actuator unit and a valve element, wherein the valve element is movable by the valve actuator unit.

2022