| 1. |
- Garcia, Arturo S., et al.
(author)
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A collaborative workspace architecture for strengthening collaboration among space scientists
- 2015
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In: Proceedings of a meeting held 7-14 March 2015, Big Sky, Montana, USA.. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781479953790 - 9781479953806 - 9781479953776 ; , s. 1133-1144
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Conference paper (peer-reviewed)abstract
- Space exploration missions have produced large data of immense value, to both research and the planning and operating of future missions. However, current datasets and simulation tools fragment teamwork, especially across disciplines and geographical location. The aerospace community already exploits virtual reality for purposes including space tele-robotics, interactive 3D visualization, simulation and training. However, collaborative virtual environments are yet to be widely deployed or routinely used in space projects. Advanced immersive and collaborative visualization systems have the potential for enhancing the efficiency and efficacy of data analysis, simplifying visual benchmarking, presentations and discussions. We present preliminary results of the EU funded international project CROSS DRIVE, which develops an infrastructure for collaborative workspaces for space science and missions. The aim is to allow remote scientific and engineering experts to collectively analyze and interpret combined datasets using shared simulation tools. The approach is to combine advanced 3D visualization techniques and interactive tools in conjunction with immersive virtuality telepresence. This will give scientists and engineers the impression of teleportation from their respective buildings across Europe, to stand together on a planetary surface, surrounded by the information and tools that they need. The conceptual architecture and proposed realization of the collaborative workspace are described. ESA's planned ExoMars mission provides the use-case for deriving user requirements and evaluating our implementation.
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| 2. |
- Bruhn, Fredrik, et al.
(author)
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Introducing Radiation Tolerant Heterogeneous Computers for Small Satellites
- 2015
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In: IEEE Aerospace Conference Proceedings, vol. 2015. - 9781479953790 ; , s. Article number 7119158-
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Conference paper (peer-reviewed)abstract
- This paper presents results and conclusions from design, manufacturing, and benchmarking of a heterogeneous computing low power fault tolerant computer, realized on an industrial Qseven® small form factor (SFF) platform. A heterogeneous computer in this context features multi-core processors (CPU), a graphical processing unit (GPU), and a field programmable gate array (FPGA). The x86 compatible CPU enables the use of vast amounts of commonly available software and operating systems, which can be used for space and harsh environments. The developed heterogeneous computer shares the same core architecture as game consoles such as Microsoft Xbox One and Sony Playstation 4 and has an aggregated computational performance in the TFLOP range. The processing power can be used for on-board intelligent data processing and higher degrees of autonomy in general. The module feature quad core 1.5 GHz 64 bit CPU (24 GFLOPs), 160 GPU shader cores (127 GFLOPs), and a 12 Mgate equivalent FPGA fabric with a safety critical ARM® Cortex-M3 MCU.
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| 3. |
- Felicetti, Leonard, et al.
(author)
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Attitude coordination strategies in satellite constellations and formation flying
- 2015
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In: 2015 IEEE Aerospace Conference. - Piscataway, NJ : IEEE Communications Society. - 9781479953790
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Conference paper (peer-reviewed)abstract
- The coordination of the attitude among different spacecraft belonging to a multiple platform system (formation or constellation) is a basic requirement in several missions, mainly the ones involving sensors like radars or optical interferometers. It is also an open topic in research, above all as it matches the characteristics of the current trend towards interoperability and federated systems. Different approaches are possible to define and chase such a coordinated attitude. The classic control strategy is the socalled leader-follower architecture, where all spacecraft depend on ("follow") the behavior of a single master. Alternatively, the behavioral approach involves a continuous re-selection of the desired target configuration which is computed on the basis of the behavior of all the platforms. A third possibility is to define a "virtual" architecture, especially suitable with respect to the mission requirements, which is not dependent on the current kinematic state of the platforms. The paper proposes a unified treatment of these concepts by using some fundamental definitions of the consensus dynamics and cooperative control. The convergence to the targeted configuration is addressed both analytically, by using Lyapunov stability criteria, and numerically, by means of numerical simulations. The attitude requirements and constraints are highlighted and a solution for the control algorithm - involving continuous actuators on each platform - is developed. A comparative analysis of different optimal control strategies, the Linear Quadratic Regulation (LQR) and the State Dependent Riccati Equation (SDRE) - suitably modified to address the needs of coordination - is presented. The results show the general value of the proposed approach with respect to either linear or nonlinear models of the dynamics.
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| 4. |
- Sihver, Lembit, 1962, et al.
(author)
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Improvements and developments of physics models in PHITS for space applications
- 2015
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In: IEEE Aerospace Conference Proceedings. - 1095-323X. - 9781479953806 ; 2015-June
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Conference paper (peer-reviewed)abstract
- Precise predictions of the radiation environment inside space vehicles, and inside the human body, are essential when planning for long term deep space missions. Since these predictions include complex geometries, as well as the contributions from many different types of radiation, including neutrons, 3-D Monte Carlo codes with precise physics models are needed. In this paper, we present improvements and developments of some physics models used in the general purpose 3-D Monte Carlo code PHITS [1]. The total reaction cross section (σR) and the decay lifetime of a projectile particle are the first essential quantities in MC calculations, since these determine the mean free path of the transported particles and the probability function according to which a projectile particle will collide within a certain distance in the matter depends on the σR. This will also scale the calculated partial fragmentation cross sections. In this paper we present comparisons of calculated and measured σR using the Kurotama Hybrid σR, model [2] which is incorporated into PHITS. The prediction of the fragmentation reactions of relativistic heavy ions is also essential for ensuring radiation safety of astronauts. The default model for nuclear-nuclear reactions is JQMD in PHITS. However, JQMD cannot accurately enough describe the nucleon and d, t, 3He and 4He induced reactions. Therefore the Intra-Nuclear Cascade of Liège (INCL) [3] has been selected as the default model for these reactions. Moreover, it has been realized that the production of light fragments is underestimated by conventional simulation codes based on a combination of intranuclear cascade and statistical decay models. This is because this combination cannot reproduce the high multiplicity events that are responsible for the production of light fragments. To better reproduce high multiplicity events, we have simulated fragmentation cross sections using a combination of JQMD/INCL, statistical multi-fragmentation model (SMM) [4,5] and the generalized evaporation model (GEM). Examples of these simulations will be presented. A new approach to describe neutron spectra of deuteron-induced reactions in the Monte Carlo simulations has also been developed by combining the INCL and the Distorted Wave Born Approximation (DWBA) calculation [6]. We have incorporated this combined method into PHITS and applied it to estimate (d,xn) spectra on light targets at incident energies ranging from 10 to 40 MeV. In this paper, we will show that the double differential cross sections obtained by INCL and DWBA successfully reproduced broad peaks and discrete peaks, respectively.
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