Gamma Ray Astronomy with Magnetized Zevatrons

Nearby sources of cosmic rays up to a ZeV(=10^21 eV) could be observed with a multi-messenger approach including secondary gamma-rays and neutrinos. If cosmic rays above ~10^18 eV are produced in magnetized environments such as galaxy clusters, the flux of secondary gamma-rays below ~1 TeV can be enhanced up to several orders of magnitudes compared to unmagnetized sources. A particular source of enhancement are synchrotron and cascade photons from e^+e^- pairs produced by protons from sources with relatively steep injection spectra proportional to E^-2.6. Such sources should be visible at the same time in ultra-high energy cosmic ray experiments and gamma-ray telescopes.Comment: 4 pages, 3 ps figure

Automated Safety Case Compilation for Product-based Argumentation

International audienceThe main goal of a safety case is to provide a seamless argumentation why the product developed is acceptably safe for the purpose it is intended to. It usually consists of different argumentations such as product-based and process-based in order to describe the means for avoiding systematic failures during development and controlling random failures during operation. The main challenge during the compilation of a safety case is to regroup and harmonize all the information available from the different development activities in order to provide evidence for the safety attribute of the product. The contribution of this paper is to provide a solution for compilation of a safety case based on automated extraction of information coming from existing work-products

Beryllium Abundances in F and G Dwarfs in Praesepe and Other Young Clusters from Keck HIRES Observations

The study of both Be and Li gives useful clues about stellar internal structure. Of particular interest is the study of these light elements in open clusters, which have a known age and metallicity. In this paper we present a study of Be abundances in 10 F-type stars in Praesepe and a comprehensive discussion about Be abundances in other open clusters: Hyades, Pleiades, Per, Coma, and UMa. We have made observations of the doublet of Be ii around 3130 A˚ in Praesepe stars, using the Keck I telescope and the High Resolution Echelle Spectrometer (HIRES). Beryllium abundances were derived from the spectra using the spectrum synthesis method. We find four stars with definite Be depletion in the temperature range of the Li dip like we found in our previous cluster studies, notably for the Hyades and Coma clusters. Putting all the clusters together, we confirm the existence of a Be dip in a narrow temperature range for F stars. Beryllium depletion in this dip is less pronounced than Li depletion. For the cooler stars there is little or no Be depletion, even though there are large depletions of Li. For stars that have little or no Li depletion, AðLiÞ! 3:0, the ratio Li/Be is 75 Æ 4:6, compared to the meteoritic ratio of 77.6. For stars cooler than $5900 K there appears to be little or no Be depletion, and the mean A(Be) is 1:30 Æ 0:02. For these cooler stars within a given cluster there is no evidence for intrinsic star-to-star differences in A(Be), with the possible exception of the cool Pleiades stars. In the temperature range of the Li-Be dip, a strong correlation exists between Li and Be, consistent with the theory of rotationally induced mixing. Moreover, the slopes of the Li versus Be correlations are different depending on the temperature range. For the full sample of 42 stars between 5900 and 6650 K the slope is 0:43 Æ 0:05 [where A(Li) is the abscissa]. The slope is 0:48 Æ 0:08 for 6300 K \u3c TeA \u3c 6650 K and 0:30 Æ 0:05 for 5900 K \u3c TeA \u3c 6300 K. For the Li plateau stars (the cooler subset), the slope is smaller as the impact of the increasing surface convection zone affects the mixing, thus depleting more Li relative to Be. The different behavior in Be depletion for clusters of different ages is consistent with the idea of slow mixing related to rotation during the main-sequence phase of evolution. The range in metallicity in this sample of clusters is only 0.2 dex, so it is difficult to discern any influence of metallicity on the Li-Be relationship; however, the mean A(Be) in the cooler Hyades stars (with ½Fe=H¼þ0:13) is 1:35 Æ 0:02, which is higher than that for the Coma stars (with ½Fe=H¼ À0:09) of 1:26 Æ 0:02 by 0.09 dex

Beryllium Abundances in F and G Dwarfs in the Coma Cluster and the Ursa Major Group from Keck HIRES Observation

The study of both light elements Li and Be in open clusters of known properties can reveal the internal structure and the mechanisms of mixing in main-sequence stars as a function of age and composition. In previous work, we have investigated the older Hyades cluster and the younger Pleiades and Per clusters. The Coma Berenices cluster and the UMa moving group are intermediate in age between the Hyades and Pleiades and provide a good linchpin for the influence of stellar age on light-element abundances; there are dips in the mid-F stars in both Li and Be in the Hyades but no Be dip and only a minor Li dip in the Pleiades. We have made observations of the resonance doublet of Be ii near 3130 A ˚ in 13 Coma and six UMa stars with the Keck I telescope and the High Resolution Echelle Spectrometer. The Be abundances were determined by spectrum synthesis. In the F dwarfs in Coma, there are both Li and Be deficiencies, indicating that the deple-tions occur during the main-sequence phase of evolution but do not become evident until an age of 200–300 Myr. For both UMa and Coma stars, the Li depletion is greater than the Be depletion at all temperatures, but there is little, if any, Be depletion in stars with Teff \u3c 6000 K. In the four clusters studied for Be, the mean Be abundance for stars with temperatures less than 6000 K is log NðBe=HÞþ12:00 ¼1:27, independent of age or metal content. For the hotter stars (5850–6680 K), the Li and Be abundances are correlated, indicating that the depletion probably occurs simultaneously; this matches the results for the field stars and the Hyades and the predictions of Li and Be depletion by rotationally induced mixing

Ultrahigh energy cosmic rays as heavy nuclei from cluster accretion shocks

Large-scale accretion shocks around massive clusters of galaxies, generically expected in hierarchical scenarios of cosmological structure formation, are shown to be potential sources of the observed ultrahigh energy cosmic rays (UHECRs) by accelerating a mixture of heavy nuclei including the iron group elements. Current observations can be explained if the source composition at injection for the heavier nuclei is somewhat enhanced from simple expectations for the accreting gas. The proposed picture should be testable by current and upcoming facilities in the near future through characteristic features in the UHECR spectrum, composition and anisotropy. The associated X-ray and gamma-ray signatures are also briefly discussed.Comment: 4 pages, 4 figures, Proceedings of the 30th ICRC, Merida, Mexico, 200

INCOBAT: Innovative Cost Efficient Management System for Next Generation High Voltage Batteries

Electro-mobility is considered as a key technology to achieve green mobility and fulfil tomorrow’s emission standards. However, different challenges still need to be faced to achieve comparable performances to conventional vehicles and finally obtain market acceptance. Two of these challenges are vehicle range and production costs. In that context, the aim of the INCOBAT project (October 2013 – December 2016) was to provide innovative and cost efficient battery management systems for next generation HV-batteries. INCOBAT presents a platform concept that achieves cost reduction, reduced complexity, increased reliability and flexibility while at the same time reaching higher energy efficiency. Advantages of this approach include: Tight control of the cell function leading to a significant increase of the driving range of the FEV; Radical cost reduction of the battery management system with respect to current solutions; Development of modular concepts for system architecture and partitioning, safety, security, reliability as well as verification and validation, thus enabling efficient integration into different vehicle platforms. The INCOBAT project focused on the following twelve technical innovations grouped into four innovation groups, which are summarized in this book: Customer needs and integration aspects Transversal innovation Technology innovatio

CONCEPTS AND TOOLS FOR THE TEST OF THE COMMUNICATION SUB-SYSTEM OF TIME-TRIGGERED DISTRIBUTED EMBEDDED SYSTEMS

ABSTRACT With the adoption of FlexRay, the time triggered paradigm has been widely accepted by the automotive industry as a means to tackle the requirements of future automotive electronics. However, when compared with traditional event-triggered systems like CAN, the benefits of higher reliability come at the cost of increased complexity during system design. In fact, to support the development of these systems adequate tool-support will be mandatory. In this paper we discuss the requirements and concepts for and present an implementation of a test and diagnosis toolset for FlexRay-based automotive distributed networks. Next to data monitoring and recording, this toolset provides facilities for fault injection and replay. Hence, the presented implementation is tailored for an embedded test and fault diagnosis and will enable an assessment of the reliability and dependability of future automotive solutions

Measurement of the small-scale 3D Lyman-α\alpha forest power spectrum

Small-scale correlations measured in the Lyman-$\alpha$ (Ly$\alpha$) forest encode information about the intergalactic medium and the primordial matter power spectrum. In this article, we present and implement a simple method to measure the 3-dimensional power spectrum, $P_{\rm 3D}$, of the Ly$\alpha$ forest at wavenumbers $k$ corresponding to small, $\sim$ Mpc scales. In order to estimate $P_{\rm 3D}$ from sparsely and unevenly distributed data samples, we rely on averaging 1-dimensional Fourier Transforms, as previously carried out to estimate the 1-dimensional power spectrum of the Ly$\alpha$ forest, $P_{\rm 1D}$. This methodology exhibits a very low computational cost. We confirm the validity of this approach through its application to Nyx cosmological hydrodynamical simulations. Subsequently, we apply our method to the eBOSS DR16 Ly$\alpha$ forest sample, providing as a proof of principle, a first $P_{\rm 3D}$ measurement averaged over two redshift bins $z=2.2$ and $z=2.4$. This work highlights the potential for forthcoming $P_{\rm 3D}$ measurements, from upcoming large spectroscopic surveys, to untangle degeneracies in the cosmological interpretation of $P_{\rm 1D}$.Comment: 27 pages, 9 figure