Fluid pumped by magnetic stress

A magnetic field rotating on the free surface of a ferrofluid layer is shown to induce considerable fluid motion toward the direction the field is rolling. The measured flow velocity i) increases with the square of the magnetic field amplitude, ii) is proportional to the thickness of the fluid layer, and iii) has a maximum at a driving frequency of about 3 kHz. The pumping speed can be estimated with a two-dimensional flow model.Comment: 3 pages, 4 figure

Multimessenger Gamma-Ray and Neutrino Coincidence Alerts using HAWC and IceCube sub-threshold Data

The High Altitude Water Cherenkov (HAWC) and IceCube observatories, through the Astrophysical Multimessenger Observatory Network (AMON) framework, have developed a multimessenger joint search for extragalactic astrophysical sources. This analysis looks for sources that emit both cosmic neutrinos and gamma rays that are produced in photo-hadronic or hadronic interactions. The AMON system is running continuously, receiving sub-threshold data (i.e. data that is not suited on its own to do astrophysical searches) from HAWC and IceCube, and combining them in real-time. We present here the analysis algorithm, as well as results from archival data collected between June 2015 and August 2018, with a total live-time of 3.0 years. During this period we found two coincident events that have a false alarm rate (FAR) of $<1$ coincidence per year, consistent with the background expectations. The real-time implementation of the analysis in the AMON system began on November 20th, 2019, and issues alerts to the community through the Gamma-ray Coordinates Network with a FAR threshold of $<4$ coincidences per year.Comment: 14 pages, 5 figures, 3 table

SimWorld – Automatic Generation of realistic Landscape models for Real Time Simulation Environments – a Remote Sensing and GIS-Data based Processing Chain

The interdisciplinary project “SimWorld” - initiated by the German Aerospace Center (DLR) - aims to improve and to facilitate the generation of virtual landscapes for driving simulators. It integrates the expertise of different research institutes working in the field of car simulation and remote sensing technology. SimWorld will provide detailed virtual copies of the real world derived from air- and satelliteborne remote sensing data, using automated geo-scientific analysis techniques for more efficiency and greater realism for landscape models. The implementation of geo-databases and GIS technology within the simulator will allow for further simulation and testing of new technologies like e.g. radar-sensors, night vision systems as well as positioning systems such as GPS and Galileo

SimWorld – Automatic Generation of realistic Landscape models for Real Time Simulation Environments – a Remote Sensing and GIS-Data based Processing Chain

The interdisciplinary project “SimWorld” - initiated by the German Aerospace Center (DLR) - aims to improve and to facilitate the generation of virtual landscapes for driving simulators. It integrates the expertise of different research institutes working in the field of car simulation and remote sensing technology. SimWorld will provide detailed virtual copies of the real world derived from air- and satellite-borne remote sensing data, using automated geo-scientific analysis techniques for more efficiency and greater realism for landscape models. The implementation of geo-databases and GIS technology within the simulator will allow for further simulation and testing of new technologies like e.g. radar-sensors, night vision systems as well as positioning systems such as GPS and Galileo

Analyse und Aufbereitung sicherheitsrelevanter Informationen von Netzwerkknoten zur Simulation von IT-AngriUen

Zunehmende Cyberwar-Aktivitäten innerhalb der letzten Jahre zeigen, dass dem Thema Sicherheit in Verbindung mit dem Internet, aber auch allgemein im Zusammenhang mit vernetzten Geräten nicht genug Beachtung geschenkt werden kann. Eine Simulation zur Ausbreitung von Schadsoftware, die neben dieser selbst auch real existierende Systeme samt installierter Software und individuell interagierende Benutzer berücksichtigt, kann Erkenntnisse hervorbringen, die sich eignen, präventives Handeln zu verbessern und so die Resilienz zu erhöhen oder im Notfall ad hoc Maßnahmen zu ergreifen. Im Rahmen dieses Dokuments wird untersucht, ob die Zusammenfassung von Informationen aus einer Netzwerktopologie, die für eine derartige Simulation benötigt werden, möglich ist.Since an increasing number of cyberwar activities showed up during the last years, security has to be considered an essential topic when interacting not only with the internet, but with networked devices in general. A simulation that considers existing systems including installed software as well as individual user interaction. This simulation, also including malware behaviour, might help to improve knowledge concerning preemptive acting and thereby improve resilience or take ad hoc measures in case of emergency. In this document it will be determined how it is possible to gather information about a network topology for such simulations

Traffic Flow Estimation from Single Satellite Images

Exploiting a special focal plane assembly of most satellites allows for the extraction of moving objects from only one multispectral satellite image. Push broom scanners as used on most earth observation satellites are composed of usually more than one CCD line – mostly one for multispectral and one for panchromatic acquisistion. Some sensors even have clearly separated CCD lines for different multispectral channels. Such satellites are for example WorldView-2 or RapidEye. During the Level-0-processing of the satellite data these bands get coregistered on the same ground level which leads to correct multispectral and exactly fitting pan images. But if objects are very high above the coregistering plane or are moving significantly in between the short acquisition time gap these objects get registered on different points in different channels. Measuring relative distances of these objects between these channels and knowing the acquisition time gap allows retrieving the speed of the objects or the height above the coregistering plane. In this paper we present our developed method in general for different satellite systems – namely RapidEye, WorldView-2 and the new Pl´eiades system. The main challenge in most cases is nevertheless the missing knowledge of the acquisition time gap between the different CCD lines and often even of the focal plane assembly. So we also present our approach to receive a coarse focal plane assembly model together with a most likely estimation of the acqusition time gaps for the different systems

Consistent characterization of semiconductor saturable absorber mirrors with singe-pulse and pump-probe spectroscopy

We study the comparability of the two most important measurement methods used for the characterization of semiconductor saturable absorber mirrors (SESAMs). For both methods, single-pulse spectroscopy (SPS) and pump-probe spectroscopy (PPS), we analyze in detail the time-dependent saturation dynamics inside a SESAM. Based on this analysis, we find that fluence-dependent PPS at complete spatial overlap and zero time delay is equivalent to SPS. We confirm our findings experimentally by comparing data from SPS and PPS of two samples. We show how to interpret this data consistently and we give explanations for possible deviations