Laser ablation of energetic polymer solutions: effect of viscosity and fluence on the splashing behavior

Laser plasma thrusters are a new kind of propulsion system for small satellites, and work with the thrust created by the laser ablation of a target. Liquid polymer solutions are very promising fuels for such systems, provided that no splashing of the target occurs, because ejection of droplets strongly decreases the performances of the system. We have investigated the nanosecond infrared laser ablation of glycidyl azide polymer solutions containing carbon nanoparticles as absorber. Shadowgraphy imaging revealed two cases, namely splashing regime and solid-like behavior. The transition between both regimes depends on the viscosity of the solution and on the laser fluence, and is explained by the recoil force acting on the target. Appropriate conditions to avoid splashing were identified, showing that this liquid polymer solution is a suitable fuel for laser plasma thruster

What is Digital about Digital Innovation? An Ontological Discussion of Digitality

“Digital” is a popular adjective for concepts related to electronic, computerized or networked processes in current research and practice. From an ontological-theoretical perspective, the prevalence of digital things triggers the question, how Digitality itself could be conceptualized. This article studies the ontology of Digitality and consequently discusses Digital Innovation (DI) from a new perspective. First, literature on Digitality is analyzed. Based on the findings, an ontological conceptual framework of Digitality (OCFD) is proposed. It describes four layers of Digitality: physical foundations, virtuality, digital culture and world, and digital metaphysics. From a human perspective, requirements to grasp and embody Digitality are highlighted, as well as the expansion of reality. Finally, Digitality is discussed as a paradigm of DI and exemplary digital phenomena are projected onto the OCFD. This paper contributes to DI research and practice through theory-building towards a better understanding of ontological characteristics and practical implications of Digitality in DI

Laser ablation of energetic polymer solutions: Effect of viscosity and fluence on the splashing behavior

ISSN:0947-8396ISSN:1432-0630ISSN:0340-379

Open data from the first and second observing runs of Advanced LIGO and Advanced Virgo

Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain data with sufficient sensitivity to detect signals routinely. In this paper we describe the data recorded by these instruments during their first and second observing runs. The main data products are gravitational-wave strain time series sampled at 16384 Hz. The datasets that include this strain measurement can be freely accessed through the Gravitational Wave Open Science Center at http://gw-openscience.org, together with data-quality information essential for the analysis of LIGO and Virgo data, documentation, tutorials, and supporting software