SAPIENT-Simulator Modelling and Architecture

Future aeronautical communications will be based on the TCP/IP protocol stack, and will occur through a number of different data-link channels (e.g., satellite, terrestrial), with multipath capabilities – the so-called multilink. Seamless vertical handover between different data-links is a requirement and it will improve the safety and reliability of AEROCOM systems, possibly enabling remote-piloted aircrafts (RPAs) for civil operations. This paper describes the modelling, design and implementation of an AEROCOM system simulator based on OMNeT++, developed in the framework of the SAPIENT EU project. The simulator includes models of the aircrafts, including their mobility, terrestrial and satellite data links and core network. Moreover, it includes a solution to simulate the effect of multilink capabilities, which enables one to test multilink decision policies

Cosmic Ray Antihelium from a Strongly Coupled Dark Sector

Standard Model extensions with a strongly coupled dark sector can induce high-multiplicity states of soft quarks. Such final states trigger extremely efficient antinucleus formation. We show that dark matter annihilation or decay into a strongly coupled sector can dramatically enhance the cosmic-ray antinuclei flux -- by six orders of magnitude in the case of ${^4\overline{\text{He}}}$. In this work, we argue that the tentative ${^3\overline{\text{He}}}$ and ${^4\overline{\text{He}}}$ events reported by the AMS-02 collaboration could be the first sign of a strongly coupled dark sector observed in nature.Comment: 9 pages, 2 figure

The Swift-BAT survey reveals the orbital period of three high-mass X-ray binaries

A growing number of previously hidden Galactic X-ray sources are now detected with recent surveys performed by the Integral and Swift satellites. Most of these new sources eluded past surveys due to their large local X-ray extinction and consequent low soft X-ray flux. The Swift-BAT performs daily monitoring of the sky in an energy band (15-150 keV) which is only marginally affected by X-ray extinction, thus allowing for the search of long periodicities in the light curve and identification of the nature of the X-ray sources. We performed a period search using the folding technique in the Swift-BAT light curves of three Integral sources: IGR J05007-7047, IGR J13186-6257 and IGR J17354-3255. Their periodograms show significant peaks at 30.77$\pm$0.01 d, 19.994$\pm$0.01 d and 8.448$\pm$0.002 d, respectively. We estimate the significance of these features from the chi squared distribution of all the trials, finding a probability less than 1.5$\times10^{-4}$ that the detections occurred due to chance. We complement our analysis with the study of their broadband X-ray emission. We identify the periodicities with the orbital periods of the sources. The periods are typical for the wind accretors X-ray binaries and we support this identification showing that also their energy spectra are compatible with an X-ray spectral emission characteristic of high-mass X-ray binaries. The spectrum of IGR J05007-704 that resides in the Large Magellanic Cloud, does not show any intrinsic local absorption, whereas the spectra of the Galactic sources IGR J17354-3255 and IGR J13186-6257 may be affected by a local absorber. The folded light curve for IGR J13186-6257 suggests a possible Be companion star.Comment: 10 pages, 14 figures. Accepted for publication in A&

The Swift-BAT hard X-ray sky monitoring unveils the orbital period of the HMXB IGR J16493-4348

IGR J16493-4348 is a supergiant high mass X-ray binary discovered by INTEGRAL in 2004. The source is detected at a significance level of $\sim21$ standard deviations in the Swift-BAT survey data collected during the first 54 months of the Swift mission. The timing analysis reveals an orbital period of $\sim$6.78 days and the presence of a full eclipse of the compact ob\ ject. The dynamical range (variability up to a factor $\sim$20) observed during the BAT monitoring suggests that IGR J16493-4348 is a wind-fed system. The derived semi-major axis of the binary system is \sim55 R_{\sun} with an orbit eccentr\ icity lower than 0.15.Comment: 4 pages, 6 figures. Accepted for publication in MNRA

SESAR EXPLORATORY RESEARCH SAPIENT PROJECT OVERVIEW

The SESAR (Single European Sky ATM Research) Exploratory Research project called SAPIENT (Satellite and terrestrial architectures improving performance, security and safety in ATM) is a program of the SESAR Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement 699328 [1][2]. It aims at defining Satellite and Terrestrial Architectures improving performance security and Safety in ATM (Air Traffic Management) through new and innovative functionalities for future CNS (Communication, Navigation and Surveillance) and ATM systems and future European RPAS (Remotely Piloted Air System) C2/C3 satellite Data Link (DL) for governmental initiatives (C2 states for Command and Control, while C3 states Command, Control and Communications). In this context it has been defined SAPIENT which is a novel cost-effective and performance-efficient system solution for aeronautical communications, aimed at adapting and optimizing the capacity and safety performance of aeronautical communication applications, e.g. CPDLC (Controller-Pilot Data Link Communications) and ADS-C (Automatic Dependent Surveillance – Contract), in view of the estimated ‘status’ of air ground ATM SoL (Safety of Life) terrestrial and satellite datalinks over actual flown trajectories. To meet these targets, SAPIENT exploits the information on actual 4D aircraft trajectories – in terms of dynamic position in space and time – and performance data of ATM Air Ground Datalinks, produced by aircraft and other elements of the ATM Communication Infrastructure [3]. The innovative aspects addressed in the SAPIENT Project are related to the TAS-I patent “System for Aeronautical Safety of Life Applications Providing Adaptation of Services and Communication Resources for Maximized Safety and Capacity Performance” [4] . Significant references for the ATM Datalink aspects are the activities undergong in SESAR on VDL2 (VHF Digital Link Mode 2) [5] and other new generation digital datalinks and in ESA on Iris [7]. The SAPIENT solution is a multilink/data link monitor and control system. It is aimed at providing information on the aircraft perception of the operational layout goodness in order to correct or operate more effectively with respect to the ATM communication goals. The main objectives are: - Support the multilink function during the selection of the optimal data link; - Foresee retroaction on the in-use data link, and change the resources during the flight, according to information obtained through it and according to the information collected from the other SAPIENT system actors; - Retroact on multilink function in order to change the priority between data links (i.e. need of load balancing in a common coverage area with traffic hot spots). The use of the SAPIENT system is expected to positively impact: - The efficiency of the data-links management in a multilink environment, resulting in less resources needed by ATM communication system elements, with main focus on effective and efficient use of RF spectrum The Communication issues in the ATM air/ground links minimizing the need of tactical interventions from ATC (Air Traffic Control) and pilots to de-conflict situations - Communication issues in the RPAS C3 satellite DL minimizing the use of RPAS safety procedure that will limit the execution of the RPAS missions - The Air Navigation Service providing a cost saving obtained by improving the Air navigation Service productivity and the frequency band usage The aim of this paper is to present the SAPIENT reference architecture and system boundaries, the SAPIENT protocol and the main SAPIENT simulation result

Accreting magnetars: a new type of high-mass X-ray binaries?

The discovery of very slow pulsations (Pspin=5560s) has solved the long-standing question of the nature of the compact object in the high-mass X-ray binary 4U 2206+54 but has posed new ones. According to spin evolutionary models in close binary systems, such slow pulsations require a neutron star magnetic field strength larger that the quantum critical value, suggesting the presence of a magnetar. We present the first XMM-Newton observations of 4U 2206+54 and investigate its spin evolution. We find that the observed spin-down rate agrees with the magnetar scenario. We analyse ISGRI/INTEGRAL observations of 4U 2206+54 to search for the previously suggested cyclotron resonance scattering feature at ~30 keV. We do not find a clear indication of the presence of the line, although certain spectra display shallow dips, not always at 30 keV. The association of these dips with a cyclotron line is very dubious because of its apparent transient nature. We also investigate the energy spectrum of 4U 2206+54 in the energy range 0.3-10 keV with unprecedented detail and report for the first time the detection of very weak 6.5 keV fluorescence iron lines. The photoelectric absorption is consistent with the interstellar value, indicating very small amount of local matter, which would explain the weakness of the florescence lines. The lack of matter locally to the source may be the consequence of the relatively large orbital separation of the two components of the binary. The wind would be too tenuous in the vicinity of the neutron star.Comment: accepted for publication in MNRA

Noncollinear paramagnetism of a GaAs two-dimensional hole system.

We have performed transport measurements in tilted magnetic fields in a two-dimensional hole system grown on the surface of a (311)A GaAs crystal. A striking asymmetry of Shubnikov-de Haas oscillations occurs upon reversing the in-plane component of the magnetic field along the low-symmetry [2[over ¯]33] axis. As usual, the magnetoconductance oscillations are symmetric with respect to reversal of the in-plane field component aligned with the high-symmetry [011[over ¯]] axis. Our observations demonstrate that an in-plane magnetic field can generate an out-of-plane component of magnetization in a low-symmetry hole system, creating new possibilities for spin manipulation.This work was supported by the Australian Research Council (ARC) under the DP scheme and by the NSF under Grant No. DMR-1310199. ARH acknowledges an ARC DOR award.This is the accepted manuscript. The final version is available from APS at http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.236401

Numerical Evolution of General Relativistic Voids

In this paper, we study the evolution of a relativistic, superhorizon-sized void embedded in a Friedmann-Robertson-Walker universe. We numerically solve the spherically symmetric general relativistic equations in comoving, synchronous coordinates. Initially, the fluid inside the void is taken to be homogeneous and nonexpanding. In a radiation- dominated universe, we find that radiation diffuses into the void at approximately the speed of light as a strong shock---the void collapses. We also find the surprising result that the cosmic collapse time (the $1^{\rm st}$-crossing time) is much smaller than previously thought, because it depends not only on the radius of the void, but also on the ratio of the temperature inside the void to that outside. If the ratio of the initial void radius to the outside Hubble radius is less than the ratio of the outside temperature to that inside, then the collapse occurs in less than the outside Hubble time. Thus, superhorizon-sized relativistic void may thermalize and homogenize relatively quickly. These new simulations revise the current picture of superhorizon-sized void evolution after first-order inflation.Comment: 37 pages plus 12 figures (upon request-- [email protected]) LaTeX, FNAL-PUB-93/005-

Bistability of Slow and Fast Traveling Waves in Fluid Mixtures

The appearence of a new type of fast nonlinear traveling wave states in binary fluid convection with increasing Soret effect is elucidated and the parameter range of their bistability with the common slower ones is evaluated numerically. The bifurcation behavior and the significantly different spatiotemporal properties of the different wave states - e.g. frequency, flow structure, and concentration distribution - are determined and related to each other and to a convenient measure of their nonlinearity. This allows to derive a limit for the applicability of small amplitude expansions. Additionally an universal scaling behavior of frequencies and mixing properties is found. PACS: 47.20.-k, 47.10.+g, 47.20.KyComment: 4 pages including 5 Postscript figure