ToBI - Team of Bielefeld A Human-Robot Interaction System for RoboCup@Home 2017

Wachsmuth S, Lier F, Meyer zu Borgsen S, Kummert J, Lach L, Sixt D. ToBI - Team of Bielefeld A Human-Robot Interaction System for RoboCup@Home 2017. Presented at the RoboCup 2017, Nagoya.The Team of Bielefeld (ToBI) has been founded in 2009. The RoboCup teams’ activities are embedded in a long-term research agenda towards human-robot interaction with laypersons in regular and smart home environments. The RoboCup@Home competition is an im- portant benchmark and milestone for this goal in terms of robot capabilities as well as the system integration effort. In order to achieve a robust and stable system performance, we apply a systematic approach for reproducible robotic experimentation including automatic tests. For RoboCup 2017, we plan to enhance this approach by simulating complete RoboCup@Home tasks. We further extend it to the RoboCup@Home standard platform Pepper. Similar to the Nao platform, the Pepper comes with its own runtime and development eco-system. Thus, one of the chal- lenges will be the cross-platform transfer of capabilities between robots based on different eco-system, e.g. the utilized middleware and application layers. In this paper, we will present a generic approach to such issues: the Cognitive Interaction Toolkit. The overall framework inherently supports the idea of open research and offers direct access to reusable components and reproducible systems via a web-based catalog. A main focus of research at Bielefeld are robots as an ambient host in a smart home or for instance as a museum’s guide. Both scenarios are highly relevant for the RoboCup@Home standard platform competition. Skills developed in these domains will be transferred to the RoboCup@Home scenarios

A lattice study of the spin structure of the Lambda hyperon

The internal spin structure of the Lambda is of special importance for the understanding of the spin structure of hadrons in general. The comparison between the nucleon and Lambda allows for a test of the relevant flavour-symmetry breaking effects. Using nonperturbatively O(a) improved Wilson fermions in the quenched approximation we have calculated the first moments of the unpolarised, longitudinally polarised and transversity quark distribution functions in the Lambda. The results indicate that flavour symmetry breaking has little effect on the internal spin structure, in accordance with model based expectations.Comment: 14 pages, 2 figure

Chandrasekhar mass explosions of white dwarfs as a model for type Ia supernovae and their contribution to cosmic nucleosynthesis

Although type Ia supernovae are widely applied as cosmological distance indicators and contribute significantly to the enrichment of the Universe with iron group elements, their physi- cal nature is not clear yet. The heterogeneous class of type Ia supernovae is divided into several subtypes according to their observational properties, and a whole variety of possible explosion scenarios has been put forward in order to explain these extraordinarily bright events. The focus of this work lies on the numerical modeling of explosions in Chandrasekhar mass carbon-oxygen white dwarfs as well as on the investigation of the nucleosynthesis yields of several explosion chan- nels. To this end, numerical simulations of the explosion, the propagation of radiation through the expanding debris, and the galactic chemical evolution of the Milky Way were conducted. It was found that, in line with earlier studies, deflagrations in Chandrasekhar mass white dwarfs are a viable model for type Iax supernovae, a subluminous subclass of type Ia supernovae. However, the parameter study employing different ignition conditions, central densities, metallicities, com- position and rigid rotation revealed that the very faint end of the subclass can not be reproduced. Furthermore, a set of gravitationally confined detonation simulations has been carried out. In this scenario an initial deflagration is followed by a detonation initiated near the surface of the white dwarf core. It could be shown that the synthetic observables do not agree with either normal or subluminous type Ia supernovae but that objects similar to SN 1991T might be explained by this explosion mechanism. Finally, the nucleosynthesis yields of various different explosion models were analyzed. This study shows that explosions in sub-Chandrasekhar mass white dwarfs with an accreted helium shell can contribute significantly to the abundance of manganese, zinc, and copper in the Universe and should be included in future galactic chemical evolution studies

Modeling Type Ia supernovae with explosions in white dwarfs near and below the Chandrasekhar mass

The progenitor evolution and the explosion mechanism of Type Ia supernovae remain unexplained. Nonetheless, substantial progress has been made over the past years with three-dimensional hydrodynamic simulations of different scenarios. Here, we review some recent work pertaining to the leading paradigms of modeling: thermonuclear explosions of white dwarf stars near and below the Chandrasekhar mass limit. We discuss implications of the different explosion channels and their predictions of observables.<br/

Metallicity-dependent nucleosynthetic yields of Type Ia supernovae originating from double detonations of sub- M Ch white dwarfs

Double detonations in sub-Chandrasekhar mass carbon-oxygen white dwarfs with helium shell are a potential explosion mechanism for a Type Ia supernova (SNe Ia). It comprises a shell detonation and subsequent core detonation. The focus of our study is on the effect of the progenitor metallicity on the nucleosynthetic yields. For this, we compute and analyse a set of eleven different models with varying core and shell masses at four different metallicities each. This results in a total of 44 models at metallicities between 0.01$Z_\odot$ and 3$Z_\odot$. Our models show a strong impact of the metallicity in the high density regime. The presence of $^{22}$Ne causes a neutron-excess which shifts the production from $^{56}$Ni to stable isotopes such as $^{54}$Fe and $^{58}$Ni in the $\alpha$-rich freeze-out regime. The isotopes of the metallicity implementation further serve as seed nuclei for additional reactions in the shell detonation. Most significantly, the production of $^{55}$Mn increases with metallicity confirming the results of previous work. A comparison of elemental ratios relative to iron shows a relatively good match to solar values for some models. Super-solar values are reached for Mn at 3$Z_\odot$ and solar values in some models at $Z_\odot$. This indicates that the required contribution of SNe Ia originating from Chandrasekhar mass WDs can be lower than estimated in orevious work to reach solar values of [Mn/Fe] at [Fe/H]$=0$. Our galactic chemical evolution models suggest that SNe Ia from sub-Chandrasekhar mass white dwarfs, along with core-collapse supernovae, could account for more than 80% of the solar Mn abundance. Using metallicity-dependent SN Ia yields helps to reproduce the upward trend of [Mn/Fe] as a function of metallicity for the solar neighborhood. These chemical evolution predictions, however, depend on the massive star yields adopted in the calculations.Comment: accepted for publication by A&

Creation of Quartz ID cards for source tracing using a multi-method approach as part of the ANR Quartz project: Lithium as a key element

International audienceQuartz is one of the most abundant minerals of the continental crust. Being highly resistant to weathering, it is ubiquitous in fluvial sediments and an ideal marker of their dynamics. The chemistry and physical properties of quartz are intricately linked and dependent on the mineral crystallization environment and subsequent history [1]. One of the main objectives of the French ANR Quartz project is to use this characteristic of quartz to trace its origin within fluvial sediments by combining conventional characterization methods with dosimetric methods such as Electronic Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL) usually used for dating. The first step to this is the characterization of the quartz signature of each of the bedrocks of the watershed of interest. In this context, Li is a critical element to study. It is one of the main trace elements of quartz and has previously been reported as active in both paramagnetic and luminescent centers which are responsible for the signal measured by ESR and OSL techniques [2,3].In this study, we focus on the Strengbach watershed (French Vosges). Its relatively small size allowed for an exhaustive sampling of the various bedrocks, including granites, gneiss, Buntsandstein sandstones and hydrothermal fractures filled with quartz. Within these samples, quartz has been systematically analyzed using cathodoluminescence (CL), Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) and Laser Induced Breakdown Spectrometry (LIBS). Laser ablation of quartz is made difficult by its hardness and transparency which can lead to intensive tearing of the sample. To ensure usable data, analyses were made on thick (100 µm) rock sections and using a more energetic laser setup than usual. Bedrock samples have also been treated mechanically (grinding, sieving and magnetic separation) and chemically (HCl, H2SiF6 and heavy liquid separation) to extract quartz grains for Electronic Spin Resonance (ESR), Thermo-Luminescence (TL) and Optically Stimulated Luminescence (OSL) analyses.Results highlight the critical role of lithium in the definition of quartz origin signature. Concentration of Li and other main trace elements (such as Al, Ti) vary depending on quartz type and origin. However, the distinction is not complete between the different groups. CL, OSL and/or ESR signals are sensitive to chemistry but also to the position of foreign atoms within the quartz lattice, providing supplementary criteria for sample distinction. Interestingly, we report a discrepancy between the signal intensity of the ESR center associated with Li and the Li concentration likely indicating the occurrence of Li at several different sites within the mineral lattice. The combination of techniques is a valuable tool to better define the role(s) and positions of Li within the quartz lattice. This both helps better understand ESR and OSL signals, thus improving associated dating techniques, and sharpen differences between quartz signatures of the different Strengbach bedrocks.[1] J. Götze, Mineralogical magazine 73 (2009) 645-671[2] J. Götze, M. Plötze, D. Habermann, Mineralogy and Petrology 71 (2001) 225-250.[3] R.I. Mashkovtsev, Y. Pan, New Developments in Quartz Research: Varieties, Crystal Chemistry and Uses in Technology (2013)

Creation of Quartz ID cards for source tracing using a multi-method approach as part of the ANR Quartz project: Lithium as a key element

International audienceQuartz is one of the most abundant minerals of the continental crust. Being highly resistant to weathering, it is ubiquitous in fluvial sediments and an ideal marker of their dynamics. The chemistry and physical properties of quartz are intricately linked and dependent on the mineral crystallization environment and subsequent history [1]. One of the main objectives of the French ANR Quartz project is to use this characteristic of quartz to trace its origin within fluvial sediments by combining conventional characterization methods with dosimetric methods such as Electronic Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL) usually used for dating. The first step to this is the characterization of the quartz signature of each of the bedrocks of the watershed of interest. In this context, Li is a critical element to study. It is one of the main trace elements of quartz and has previously been reported as active in both paramagnetic and luminescent centers which are responsible for the signal measured by ESR and OSL techniques [2,3].In this study, we focus on the Strengbach watershed (French Vosges). Its relatively small size allowed for an exhaustive sampling of the various bedrocks, including granites, gneiss, Buntsandstein sandstones and hydrothermal fractures filled with quartz. Within these samples, quartz has been systematically analyzed using cathodoluminescence (CL), Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) and Laser Induced Breakdown Spectrometry (LIBS). Laser ablation of quartz is made difficult by its hardness and transparency which can lead to intensive tearing of the sample. To ensure usable data, analyses were made on thick (100 µm) rock sections and using a more energetic laser setup than usual. Bedrock samples have also been treated mechanically (grinding, sieving and magnetic separation) and chemically (HCl, H2SiF6 and heavy liquid separation) to extract quartz grains for Electronic Spin Resonance (ESR), Thermo-Luminescence (TL) and Optically Stimulated Luminescence (OSL) analyses.Results highlight the critical role of lithium in the definition of quartz origin signature. Concentration of Li and other main trace elements (such as Al, Ti) vary depending on quartz type and origin. However, the distinction is not complete between the different groups. CL, OSL and/or ESR signals are sensitive to chemistry but also to the position of foreign atoms within the quartz lattice, providing supplementary criteria for sample distinction. Interestingly, we report a discrepancy between the signal intensity of the ESR center associated with Li and the Li concentration likely indicating the occurrence of Li at several different sites within the mineral lattice. The combination of techniques is a valuable tool to better define the role(s) and positions of Li within the quartz lattice. This both helps better understand ESR and OSL signals, thus improving associated dating techniques, and sharpen differences between quartz signatures of the different Strengbach bedrocks.[1] J. Götze, Mineralogical magazine 73 (2009) 645-671[2] J. Götze, M. Plötze, D. Habermann, Mineralogy and Petrology 71 (2001) 225-250.[3] R.I. Mashkovtsev, Y. Pan, New Developments in Quartz Research: Varieties, Crystal Chemistry and Uses in Technology (2013)