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  Subjects -> COMPUTER SCIENCE (Total: 2011 journals)
    - ANIMATION AND SIMULATION (30 journals)
    - ARTIFICIAL INTELLIGENCE (98 journals)
    - AUTOMATION AND ROBOTICS (98 journals)
    - CLOUD COMPUTING AND NETWORKS (61 journals)
    - COMPUTER ARCHITECTURE (9 journals)
    - COMPUTER ENGINEERING (9 journals)
    - COMPUTER GAMES (16 journals)
    - COMPUTER PROGRAMMING (24 journals)
    - COMPUTER SCIENCE (1172 journals)
    - COMPUTER SECURITY (46 journals)
    - DATA BASE MANAGEMENT (13 journals)
    - DATA MINING (32 journals)
    - E-BUSINESS (22 journals)
    - E-LEARNING (29 journals)
    - ELECTRONIC DATA PROCESSING (21 journals)
    - IMAGE AND VIDEO PROCESSING (39 journals)
    - INFORMATION SYSTEMS (108 journals)
    - INTERNET (92 journals)
    - SOCIAL WEB (50 journals)
    - SOFTWARE (34 journals)
    - THEORY OF COMPUTING (8 journals)

COMPUTER SCIENCE (1172 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 872 Journals sorted alphabetically
3D Printing and Additive Manufacturing     Full-text available via subscription   (Followers: 15)
Abakós     Open Access   (Followers: 4)
ACM Computing Surveys     Hybrid Journal   (Followers: 24)
ACM Journal on Computing and Cultural Heritage     Hybrid Journal   (Followers: 9)
ACM Journal on Emerging Technologies in Computing Systems     Hybrid Journal   (Followers: 13)
ACM Transactions on Accessible Computing (TACCESS)     Hybrid Journal   (Followers: 4)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 16)
ACM Transactions on Applied Perception (TAP)     Hybrid Journal   (Followers: 6)
ACM Transactions on Architecture and Code Optimization (TACO)     Hybrid Journal   (Followers: 9)
ACM Transactions on Autonomous and Adaptive Systems (TAAS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Computation Theory (TOCT)     Hybrid Journal   (Followers: 12)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 3)
ACM Transactions on Computer Systems (TOCS)     Hybrid Journal   (Followers: 18)
ACM Transactions on Computer-Human Interaction     Hybrid Journal   (Followers: 15)
ACM Transactions on Computing Education (TOCE)     Hybrid Journal   (Followers: 6)
ACM Transactions on Design Automation of Electronic Systems (TODAES)     Hybrid Journal   (Followers: 2)
ACM Transactions on Economics and Computation     Hybrid Journal  
ACM Transactions on Embedded Computing Systems (TECS)     Hybrid Journal   (Followers: 4)
ACM Transactions on Information Systems (TOIS)     Hybrid Journal   (Followers: 21)
ACM Transactions on Intelligent Systems and Technology (TIST)     Hybrid Journal   (Followers: 8)
ACM Transactions on Interactive Intelligent Systems (TiiS)     Hybrid Journal   (Followers: 4)
ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP)     Hybrid Journal   (Followers: 10)
ACM Transactions on Reconfigurable Technology and Systems (TRETS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Sensor Networks (TOSN)     Hybrid Journal   (Followers: 9)
ACM Transactions on Speech and Language Processing (TSLP)     Hybrid Journal   (Followers: 10)
ACM Transactions on Storage     Hybrid Journal  
ACS Applied Materials & Interfaces     Full-text available via subscription   (Followers: 25)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Ad Hoc Networks     Hybrid Journal   (Followers: 11)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Advanced Engineering Materials     Hybrid Journal   (Followers: 26)
Advanced Science Letters     Full-text available via subscription   (Followers: 9)
Advances in Adaptive Data Analysis     Hybrid Journal   (Followers: 7)
Advances in Artificial Intelligence     Open Access   (Followers: 16)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 6)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 18)
Advances in Computer Science : an International Journal     Open Access   (Followers: 15)
Advances in Computing     Open Access   (Followers: 2)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 52)
Advances in Engineering Software     Hybrid Journal   (Followers: 27)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 11)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 27)
Advances in Human-Computer Interaction     Open Access   (Followers: 21)
Advances in Materials Sciences     Open Access   (Followers: 16)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Remote Sensing     Open Access   (Followers: 40)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Advances in Technology Innovation     Open Access   (Followers: 4)
AEU - International Journal of Electronics and Communications     Hybrid Journal   (Followers: 8)
African Journal of Information and Communication     Open Access   (Followers: 8)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 4)
Air, Soil & Water Research     Open Access   (Followers: 9)
AIS Transactions on Human-Computer Interaction     Open Access   (Followers: 6)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1)
Algorithms     Open Access   (Followers: 11)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 5)
American Journal of Computational Mathematics     Open Access   (Followers: 4)
American Journal of Information Systems     Open Access   (Followers: 5)
American Journal of Sensor Technology     Open Access   (Followers: 4)
Anais da Academia Brasileira de Ciências     Open Access   (Followers: 2)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 7)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Animation Practice, Process & Production     Hybrid Journal   (Followers: 5)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Data Science     Hybrid Journal   (Followers: 11)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 12)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Software Engineering     Hybrid Journal   (Followers: 13)
Annual Reviews in Control     Hybrid Journal   (Followers: 6)
Anuario Americanista Europeo     Open Access  
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applied and Computational Harmonic Analysis     Full-text available via subscription   (Followers: 1)
Applied Artificial Intelligence: An International Journal     Hybrid Journal   (Followers: 13)
Applied Categorical Structures     Hybrid Journal   (Followers: 2)
Applied Clinical Informatics     Hybrid Journal   (Followers: 2)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Computer Systems     Open Access   (Followers: 2)
Applied Informatics     Open Access  
Applied Mathematics and Computation     Hybrid Journal   (Followers: 33)
Applied Medical Informatics     Open Access   (Followers: 10)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Soft Computing     Hybrid Journal   (Followers: 15)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 5)
Architectural Theory Review     Hybrid Journal   (Followers: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 5)
Archive of Numerical Software     Open Access  
Archives and Museum Informatics     Hybrid Journal   (Followers: 135)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Artifact     Hybrid Journal   (Followers: 2)
Artificial Life     Hybrid Journal   (Followers: 7)
Asia Pacific Journal on Computational Engineering     Open Access  
Asia-Pacific Journal of Information Technology and Multimedia     Open Access   (Followers: 1)
Asian Journal of Computer Science and Information Technology     Open Access  
Asian Journal of Control     Hybrid Journal  
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
Australian Educational Computing     Open Access   (Followers: 1)
Automatic Control and Computer Sciences     Hybrid Journal   (Followers: 4)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Automatica     Hybrid Journal   (Followers: 11)
Automation in Construction     Hybrid Journal   (Followers: 6)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Basin Research     Hybrid Journal   (Followers: 5)
Behaviour & Information Technology     Hybrid Journal   (Followers: 52)
Biodiversity Information Science and Standards     Open Access  
Bioinformatics     Hybrid Journal   (Followers: 285)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 14)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 18)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 34)
Briefings in Bioinformatics     Hybrid Journal   (Followers: 47)
British Journal of Educational Technology     Hybrid Journal   (Followers: 136)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
c't Magazin fuer Computertechnik     Full-text available via subscription   (Followers: 2)
CALCOLO     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Journal of Electrical and Computer Engineering     Full-text available via subscription   (Followers: 14)
Capturing Intelligence     Full-text available via subscription  
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cell Communication and Signaling     Open Access   (Followers: 2)
Central European Journal of Computer Science     Hybrid Journal   (Followers: 5)
CERN IdeaSquare Journal of Experimental Innovation     Open Access   (Followers: 1)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
ChemSusChem     Hybrid Journal   (Followers: 7)
China Communications     Full-text available via subscription   (Followers: 7)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
CIN Computers Informatics Nursing     Full-text available via subscription   (Followers: 11)
Circuits and Systems     Open Access   (Followers: 15)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
CLEI Electronic Journal     Open Access  
Clin-Alert     Hybrid Journal   (Followers: 1)
Cluster Computing     Hybrid Journal   (Followers: 1)
Cognitive Computation     Hybrid Journal   (Followers: 4)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Communication Methods and Measures     Hybrid Journal   (Followers: 12)
Communication Theory     Hybrid Journal   (Followers: 20)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Algebra     Hybrid Journal   (Followers: 3)
Communications in Partial Differential Equations     Hybrid Journal   (Followers: 3)
Communications of the ACM     Full-text available via subscription   (Followers: 55)
Communications of the Association for Information Systems     Open Access   (Followers: 18)
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering     Hybrid Journal   (Followers: 3)
Complex & Intelligent Systems     Open Access   (Followers: 1)
Complex Adaptive Systems Modeling     Open Access  
Complex Analysis and Operator Theory     Hybrid Journal   (Followers: 2)
Complexity     Hybrid Journal   (Followers: 6)
Complexus     Full-text available via subscription  
Composite Materials Series     Full-text available via subscription   (Followers: 9)
Computación y Sistemas     Open Access  
Computation     Open Access  
Computational and Applied Mathematics     Hybrid Journal   (Followers: 2)
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2)
Computational and Mathematical Organization Theory     Hybrid Journal   (Followers: 2)
Computational and Structural Biotechnology Journal     Open Access   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Astrophysics and Cosmology     Open Access   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computational Cognitive Science     Open Access   (Followers: 2)
Computational Complexity     Hybrid Journal   (Followers: 4)
Computational Condensed Matter     Open Access  
Computational Ecology and Software     Open Access   (Followers: 9)
Computational Economics     Hybrid Journal   (Followers: 9)
Computational Geosciences     Hybrid Journal   (Followers: 15)
Computational Linguistics     Open Access   (Followers: 22)
Computational Management Science     Hybrid Journal  
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 4)
Computational Methods and Function Theory     Hybrid Journal  
Computational Molecular Bioscience     Open Access   (Followers: 2)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Particle Mechanics     Hybrid Journal   (Followers: 1)
Computational Research     Open Access   (Followers: 1)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computational Science and Techniques     Open Access  
Computational Statistics     Hybrid Journal   (Followers: 14)
Computational Statistics & Data Analysis     Hybrid Journal   (Followers: 30)
Computer     Full-text available via subscription   (Followers: 91)
Computer Aided Surgery     Hybrid Journal   (Followers: 5)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 8)
Computer Communications     Hybrid Journal   (Followers: 10)
Computer Engineering and Applications Journal     Open Access   (Followers: 5)
Computer Journal     Hybrid Journal   (Followers: 9)
Computer Methods in Applied Mechanics and Engineering     Hybrid Journal   (Followers: 22)
Computer Methods in Biomechanics and Biomedical Engineering     Hybrid Journal   (Followers: 12)
Computer Methods in the Geosciences     Full-text available via subscription   (Followers: 2)
Computer Music Journal     Hybrid Journal   (Followers: 18)
Computer Physics Communications     Hybrid Journal   (Followers: 6)
Computer Science - Research and Development     Hybrid Journal   (Followers: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computer Science and Information Technology     Open Access   (Followers: 13)
Computer Science Education     Hybrid Journal   (Followers: 14)
Computer Science Journal     Open Access   (Followers: 22)

        1 2 3 4 5 6 | Last

Journal Cover CEAS Space Journal
  [SJR: 0.221]   [H-I: 5]   [2 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1868-2510 - ISSN (Online) 1868-2502
   Published by Springer-Verlag Homepage  [2355 journals]
  • Editorial: special issue on astrodynamics tools and techniques
    • Authors: G. Ortega Hernando; A. Martinez Barrio; C. Yabar Valles; R. Jehn
      PubDate: 2018-02-06
      DOI: 10.1007/s12567-018-0195-7
       
  • Calibration OGSEs for multichannel radiometers for Mars atmosphere studies
    • Authors: J. J. Jiménez; F. J Álvarez; M. Gonzalez-Guerrero; V. Apéstigue; I. Martín; J. M. Fernández; A. A. Fernán; I. Arruego
      Abstract: This work describes several Optical Ground Support Equipment (OGSEs) developed by INTA (Spanish Institute of Aerospace Technology—Instituto Nacional de Técnica Aeroespacial) for the calibration and characterization of their self-manufactured multichannel radiometers (solar irradiance sensors—SIS) developed for working on the surface of Mars and studying the atmosphere of that planet. Nowadays, INTA is developing two SIS for the ESA ExoMars 2020 and for the JPL/NASA Mars 2020 missions. These calibration OGSEs have been improved since the first model in 2011 developed for Mars MetNet Precursor mission. This work describes the currently used OGSE. Calibration tests provide an objective evidence of the SIS performance, allowing the conversion of the electrical sensor output into accurate physical measurements (irradiance) with uncertainty bounds. Calibration results of the SIS on board of the Dust characterisation, Risk assessment, and Environment Analyzer on the Martian Surface (DREAMS) on board the ExoMars 2016 Schiaparelli module (EDM—entry and descent module) are also presented, as well as their error propagation. Theoretical precision and accuracy of the instrument are determined by these results. Two types of OGSE are used as a function of the pursued aim: calibration OGSEs and Optical Fast Verification (OFV) GSE. Calibration OGSEs consist of three setups which characterize with the highest possible accuracy, the responsivity, the angular response and the thermal behavior; OFV OGSE verify that the performance of the sensor is close to nominal after every environmental and qualification test. Results show that the accuracy of the calibrated sensors is a function of the accuracy of the optical detectors and of the light conditions. For normal direct incidence and diffuse light, the accuracy is in the same order of uncertainty as that of the reference cell used for fixing the irradiance, which is about 1%.
      PubDate: 2018-02-01
      DOI: 10.1007/s12567-018-0194-8
       
  • GOES-R active vibration damping controller design, implementation, and
           on-orbit performance
    • Authors: Brian R. Clapp; Harald J. Weigl; Neil E. Goodzeit; Delano R. Carter; Timothy J. Rood
      Abstract: GOES-R series spacecraft feature a number of flexible appendages with modal frequencies below 3.0 Hz which, if excited by spacecraft disturbances, can be sources of undesirable jitter perturbing spacecraft pointing. To meet GOES-R pointing stability requirements, the spacecraft flight software implements an Active Vibration Damping (AVD) rate control law which acts in parallel with the nadir point attitude control law. The AVD controller commands spacecraft reaction wheel actuators based upon Inertial Measurement Unit (IMU) inputs to provide additional damping for spacecraft structural modes below 3.0 Hz which vary with solar wing angle. A GOES-R spacecraft dynamics and attitude control system identified model is constructed from pseudo-random reaction wheel torque commands and IMU angular rate response measurements occurring over a single orbit during spacecraft post-deployment activities. The identified Fourier model is computed on the ground, uplinked to the spacecraft flight computer, and the AVD controller filter coefficients are periodically computed on-board from the Fourier model. Consequently, the AVD controller formulation is based not upon pre-launch simulation model estimates but upon on-orbit nadir point attitude control and time-varying spacecraft dynamics. GOES-R high-fidelity time domain simulation results herein demonstrate the accuracy of the AVD identified Fourier model relative to the pre-launch spacecraft dynamics and control truth model. The AVD controller on-board the GOES-16 spacecraft achieves more than a ten-fold increase in structural mode damping for the fundamental solar wing mode while maintaining controller stability margins and ensuring that the nadir point attitude control bandwidth does not fall below 0.02 Hz. On-orbit GOES-16 spacecraft appendage modal frequencies and damping ratios are quantified based upon the AVD system identification, and the increase in modal damping provided by the AVD controller for each structural mode is presented. The GOES-16 spacecraft AVD controller frequency domain stability margins and nadir point attitude control bandwidth are presented along with on-orbit time domain disturbance response performance.
      PubDate: 2018-01-30
      DOI: 10.1007/s12567-017-0190-4
       
  • Hybrid optical navigation by crater detection for lunar pin-point landing:
           trajectories from helicopter flight tests
    • Authors: Guilherme F. Trigo; Bolko Maass; Hans Krüger; Stephan Theil
      Abstract: Accurate autonomous navigation capabilities are essential for future lunar robotic landing missions with a pin-point landing requirement, since in the absence of direct line of sight to ground control during critical approach and landing phases, or when facing long signal delays the herein before mentioned capability is needed to establish a guidance solution to reach the landing site reliably. This paper focuses on the processing and evaluation of data collected from flight tests that consisted of scaled descent scenarios where the unmanned helicopter of approximately 85 kg approached a landing site from altitudes of 50 m down to 1 m for a downrange distance of 200 m. Printed crater targets were distributed along the ground track and their detection provided earth-fixed measurements. The Crater Navigation (CNav) algorithm used to detect and match the crater targets is an unmodified method used for real lunar imagery. We analyze the absolute position and attitude solutions of CNav obtained and recorded during these flight tests, and investigate the attainable quality of vehicle pose estimation using both CNav and measurements from a tactical-grade inertial measurement unit. The navigation filter proposed for this end corrects and calibrates the high-rate inertial propagation with the less frequent crater navigation fixes through a closed-loop, loosely coupled hybrid setup. Finally, the attainable accuracy of the fused solution is evaluated by comparison with the on-board ground-truth solution of a dual-antenna high-grade GNSS receiver. It is shown that the CNav is an enabler for building autonomous navigation systems with high quality and suitability for exploration mission scenarios.
      PubDate: 2018-01-25
      DOI: 10.1007/s12567-017-0188-y
       
  • End-to-end simulation and verification of GNC and robotic systems
           considering both space segment and ground segment
    • Authors: Heike Benninghoff; Florian Rems; Eicke Risse; Bernhard Brunner; Martin Stelzer; Rainer Krenn; Matthias Reiner; Christian Stangl; Marcin Gnat
      Abstract: In the framework of a project called on-orbit servicing end-to-end simulation, the final approach and capture of a tumbling client satellite in an on-orbit servicing mission are simulated. The necessary components are developed and the entire end-to-end chain is tested and verified. This involves both on-board and on-ground systems. The space segment comprises a passive client satellite, and an active service satellite with its rendezvous and berthing payload. The space segment is simulated using a software satellite simulator and two robotic, hardware-in-the-loop test beds, the European Proximity Operations Simulator (EPOS) 2.0 and the OOS-Sim. The ground segment is established as for a real servicing mission, such that realistic operations can be performed from the different consoles in the control room. During the simulation of the telerobotic operation, it is important to provide a realistic communication environment with different parameters like they occur in the real world (realistic delay and jitter, for example).
      PubDate: 2018-01-23
      DOI: 10.1007/s12567-017-0192-2
       
  • Multiple spacecraft configuration designs for coordinated flight missions
    • Authors: Federico Fumenti; Stephan Theil
      Abstract: Coordinated flight allows the replacement of a single monolithic spacecraft with multiple smaller ones, based on the principle of distributed systems. According to the mission objectives and to ensure a safe relative motion, constraints on the relative distances need to be satisfied. Initially, differential perturbations are limited by proper orbit design. Then, the induced differential drifts can be properly handled through corrective maneuvers. In this work, several designs are surveyed, defining the initial configuration of a group of spacecraft while counteracting the differential perturbations. For each of the investigated designs, focus is placed upon the number of deployable spacecraft and on the possibility to ensure safe relative motion through station keeping of the initial configuration, with particular attention to the required \(\varDelta V\) budget and the constraints violations.
      PubDate: 2018-01-19
      DOI: 10.1007/s12567-018-0193-9
       
  • MONTE: the next generation of mission design and navigation software
    • Authors: Scott Evans; William Taber; Theodore Drain; Jonathon Smith; Hsi-Cheng Wu; Michelle Guevara; Richard Sunseri; James Evans
      Abstract: The Mission analysis, Operations and Navigation Toolkit Environment (MONTE) (Sunseri et al. in NASA Tech Briefs 36(9), 2012) is an astrodynamic toolkit produced by the Mission Design and Navigation Software Group at the Jet Propulsion Laboratory. It provides a single integrated environment for all phases of deep space and Earth orbiting missions. Capabilities include: trajectory optimization and analysis, operational orbit determination, flight path control, and 2D/3D visualization. MONTE is presented to the user as an importable Python language module. This allows a simple but powerful user interface via CLUI or script. In addition, the Python interface allows MONTE to be used seamlessly with other canonical scientific programming tools such as SciPy, NumPy, and Matplotlib. MONTE is the prime operational orbit determination software for all JPL navigated missions.
      PubDate: 2018-01-06
      DOI: 10.1007/s12567-017-0171-7
       
  • NanoVipa: a miniaturized high-resolution echelle spectrometer, for the
           monitoring of young stars from a 6U Cubesat
    • Authors: G. Bourdarot; E. Le Coarer; X. Bonfils; E. Alecian; P. Rabou; Y. Magnard
      Pages: 411 - 419
      Abstract: We introduce to astrophysical instrumentation and space optics the use of virtually imaged phased array (VIPA) to shrink échelle spectrometers and/or increase their resolution. Here, we report on both a concept of an echelle spectrometer with resolution \(R=50{,}000\) (@653nm), which fits a 6U nanosatellite platform ( \({{1{\rm U}= 10\,{\rm cm} \times 10\,{\rm cm} \times 10\,{\rm cm}}}\) ), and on our laboratory tests on a \(R=200{,}000\) demonstrator. The outline of our paper is as follows: Sect. 1 introduces our concept of a 6U payload comprising an échelle spectrometer based on the VIPA. We present also the science cases of monitoring young stars, and the wider science landscape amenable with larger telescopes. Section 2 gives a more detailed description of the VIPA and of its implementation in a cross-dispersed spectrometer. Section 3 shows the first results at \(R=200{,}000\) we already achieved at the Institut de Planétologie et d’Astrophysique de Grenoble (IPAG). Finally, Sect. 4 is a discussion on the remaining technical points to study.
      PubDate: 2017-12-01
      DOI: 10.1007/s12567-017-0168-2
      Issue No: Vol. 9, No. 4 (2017)
       
  • Fused silica GRISMs manufactured by hydrophilic direct bonding at moderate
           heating
    • Authors: G. Kalkowski; K. Grabowski; G. Harnisch; T. Flügel-Paul; U. Zeitner; S. Risse
      Pages: 433 - 440
      Abstract: For high-resolution spectroscopy in space, GRISM elements—obtained by patterning gratings onto a prism surface—find increasing applications. We report on GRISM manufacturing by joining the individual functional elements—prisms and gratings—to suitable components by the technology of hydrophilic direct bonding. Fused silica was used as a substrate material and binary gratings were fabricated by standard e-beam lithography and dry etching. Alignment of the grating dispersion direction to the prism angle was realized by passive adjustment on dedicated bonding gear matched to the substrate geometry. Materials adapted bonds of high transmission, stiffness, and strength were obtained after heat treatment at temperatures of about 200 °C in vacuum. Examples for bonding uncoated as well as coated grating surfaces are given. The results illustrate the great potential of hydrophilic glass direct bonding for manufacturing transmission optics to be used in space or other heavy duty applications.
      PubDate: 2017-12-01
      DOI: 10.1007/s12567-017-0158-4
      Issue No: Vol. 9, No. 4 (2017)
       
  • Complex optical interference filters with stress compensation for space
           applications
    • Authors: Thomas Begou; Hélène Krol; Dragan Stojcevski; Fabien Lemarchand; Michel Lequime; Catherine Grezes-Besset; Julien Lumeau
      Pages: 441 - 449
      Abstract: We present hereafter a study of complex bandpass optical interference filters with central wavelengths ranging in blue region or in the near infrared. For these applications, the required functions are particularly complex as they must present a very narrow bandwidth as well as a high level of rejection over a broad spectral range. Moreover, these components must have a good flatness meaning that the stress induced by the different layers has to be taken in account in the filter design. We present a thorough study of these filters including their design, fabrication using Plasma Assisted Reactive Magnetron Sputtering (PARMS) and characterization. Excellent agreement between experimental and theoretical spectral performances associated with a final sag of 326 and 13 nm, and uniformity from −0.05 to 0.10 and −0.10 to 0.20% are demonstrated for the two manufactured filters.
      PubDate: 2017-12-01
      DOI: 10.1007/s12567-017-0149-5
      Issue No: Vol. 9, No. 4 (2017)
       
  • Parasitic light scattered by complex optical coatings: modelization and
           metrology
    • Authors: Myriam Zerrad; Michel Lequime; Simona Liukaityte; Claude Amra
      Pages: 473 - 484
      Abstract: Optical components realized for space applications have to be mastered in term of parasitic light. This paper present the last improvements performed at the Institute Fresnel to predict and measure scattering losses of optical components with a special care to complex optical coatings. Agreement between numerical models and metrology is now excellent. Some examples will be presented.
      PubDate: 2017-12-01
      DOI: 10.1007/s12567-017-0156-6
      Issue No: Vol. 9, No. 4 (2017)
       
  • Developments of high frequency and intensity stabilized lasers for space
           gravitational wave detector DECIGO/B-DECIGO
    • Authors: Aru Suemasa; Ayumi Shimo-oku; Ken’ichi Nakagawa; Mitsuru Musha
      Pages: 485 - 491
      Abstract: In Japan, not only the ground-based gravitational wave (GW) detector mission KAGRA but also the space GW detector mission DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) and its milestone mission B-DECIGO have been promoted. The designed strain sensitivity of DECIGO and B-DECIGO are δL/L < 10−23. Since the GW detector requires high power and highly-stable light source, we have developed the light source with high frequency and intensity stability for DECIGO and B-DECIGO. The frequency of the Yb-doped fiber DFB lasers are stabilized to the iodine saturated absorption at 515 nm, and the intensity of the laser at 1 Hz (observation band) is stabilized by controlling the pump source of an Yb-doped fiber amplifier. The intensity of the laser at 200 kHz (modulation band) is also stabilized using an acousto-optic modulator to improve the frequency stability of the laser. In the consequences, we obtain the frequency stability of δf = 0.4 Hz/√Hz (in-loop) at 1 Hz, and the intensity stability of δI/I = 1.2 × 10−7/√Hz (out-of-loop) and δI/I = 1.5 × 10−7/√Hz (in-loop) at 1 Hz and 200 kHz, respectively.
      PubDate: 2017-12-01
      DOI: 10.1007/s12567-017-0151-y
      Issue No: Vol. 9, No. 4 (2017)
       
  • Architectural elements of hybrid navigation systems for future space
           transportation
    • Authors: Guilherme F. Trigo; Stephan Theil
      Abstract: The fundamental limitations of inertial navigation, currently employed by most launchers, have raised interest for GNSS-aided solutions. Combination of inertial measurements and GNSS outputs allows inertial calibration online, solving the issue of inertial drift. However, many challenges and design options unfold. In this work we analyse several architectural elements and design aspects of a hybrid GNSS/INS navigation system conceived for space transportation. The most fundamental architectural features such as coupling depth, modularity between filter and inertial propagation, and open-/closed-loop nature of the configuration, are discussed in the light of the envisaged application. Importance of the inertial propagation algorithm and sensor class in the overall system are investigated, being the handling of sensor errors and uncertainties that arise with lower grade sensory also considered. In terms of GNSS outputs we consider receiver solutions (position and velocity) and raw measurements (pseudorange, pseudorange-rate and time-difference carrier phase). Receiver clock error handling options and atmospheric error correction schemes for these measurements are analysed under flight conditions. System performance with different GNSS measurements is estimated through covariance analysis, being the differences between loose and tight coupling emphasized through partial outage simulation. Finally, we discuss options for filter algorithm robustness against non-linearities and system/measurement errors. A possible scheme for fault detection, isolation and recovery is also proposed.
      PubDate: 2017-12-27
      DOI: 10.1007/s12567-017-0187-z
       
  • Experimental validation of solid rocket motor damping models
    • Authors: Cristina Riso; Sebastiaan Fransen; Franco Mastroddi; Giuliano Coppotelli; Francesco Trequattrini; Alessio De Vivo
      Abstract: In design and certification of spacecraft, payload/launcher coupled load analyses are performed to simulate the satellite dynamic environment. To obtain accurate predictions, the system damping properties must be properly taken into account in the finite element model used for coupled load analysis. This is typically done using a structural damping characterization in the frequency domain, which is not applicable in the time domain. Therefore, the structural damping matrix of the system must be converted into an equivalent viscous damping matrix when a transient coupled load analysis is performed. This paper focuses on the validation of equivalent viscous damping methods for dynamically condensed finite element models via correlation with experimental data for a realistic structure representative of a slender launch vehicle with solid rocket motors. A second scope of the paper is to investigate how to conveniently choose a single combination of Young’s modulus and structural damping coefficient—complex Young’s modulus—to approximate the viscoelastic behavior of a solid propellant material in the frequency band of interest for coupled load analysis. A scaled-down test article inspired to the Z9-ignition Vega launcher configuration is designed, manufactured, and experimentally tested to obtain data for validation of the equivalent viscous damping methods. The Z9-like component of the test article is filled with a viscoelastic material representative of the Z9 solid propellant that is also preliminarily tested to investigate the dependency of the complex Young’s modulus on the excitation frequency and provide data for the test article finite element model. Experimental results from seismic and shock tests performed on the test configuration are correlated with numerical results from frequency and time domain analyses carried out on its dynamically condensed finite element model to assess the applicability of different equivalent viscous damping methods to describe damping properties of slender launch vehicles in payload/launcher coupled load analysis.
      PubDate: 2017-12-21
      DOI: 10.1007/s12567-017-0191-3
       
  • Design and validation of a GNC system for missions to asteroids: the AIM
           scenario
    • Authors: A. Pellacani; P. Kicman; M. Suatoni; M. Casasco; J. Gil; I. Carnelli
      Abstract: Deep space missions, and in particular missions to asteroids, impose a certain level of autonomy that depends on the mission objectives. If the mission requires the spacecraft to perform close approaches to the target body (the extreme case being a landing scenario), the autonomy level must be increased to guarantee the fast and reactive response which is required in both nominal and contingency operations. The GNC system must be designed in accordance with the required level of autonomy. The GNC system designed and tested in the frame of ESA’s Asteroid Impact Mission (AIM) system studies (Phase A/B1 and Consolidation Phase) is an example of an autonomous GNC system that meets the challenging objectives of AIM. The paper reports the design of such GNC system and its validation through a DDVV plan that includes Model-in-the-Loop and Hardware-in-the-Loop testing. Main focus is the translational navigation, which is able to provide online the relative state estimation with respect to the target body using exclusively cameras as relative navigation sensors. The relative navigation outputs are meant to be used for nominal spacecraft trajectory corrections as well as to estimate the collision risk with the asteroid and, if needed, to command the execution of a collision avoidance manoeuvre to guarantee spacecraft safety
      PubDate: 2017-12-14
      DOI: 10.1007/s12567-017-0189-x
       
  • Experimental assessment of the performance of ablative heat shield
           materials from plasma wind tunnel testing
    • Authors: S. Löhle; T. Hermann; F. Zander
      Abstract: A method for assessing the performance of typical heat shield materials is presented in this paper. Three different material samples, the DLR material Zuram, the Airbus material Asterm and the carbon preform Calcarb were tested in the IRS plasma wind tunnel PWK1 at the same nominal condition. State of the art diagnostic tools, i.e., surface temperature with pyrometry and thermography and boundary layer optical emission spectroscopy were completed by photogrammetric surface recession measurements. These data allow the assessment of the net heat flux for each material. The analysis shows that the three materials each have a different effect on heat flux mitigation with ASTERM showing the largest reduction in surface heat flux. The effect of pyrolysis and blowing is clearly observed and the heat flux reduction can be determined from an energy balance.
      PubDate: 2017-12-11
      DOI: 10.1007/s12567-017-0186-0
       
  • Modal analysis of passive flow control for the turbulent wake of a generic
           planar space launcher
    • Authors: S. Loosen; V. Statnikov; M. Meinke; W. Schröder
      Abstract: The turbulent wake of a generic planar space launcher equipped with two passive flow control devices is simulated using a zonal RANS–LES method and analyzed by dynamic mode decomposition (DMD). In the first approach, the effect of a classical boat tail on the wake is examined. In the second concept, a flow control device consisting of semi-circular lobes integrated at the base shoulder of the main body is used. The objective of the two concepts is to reduce the reattachment length and thus the lever arm of the forces as well as to stabilize the separated shear layer. Using a boat tail, the reattachment length can be reduced by 50%. Furthermore, it is shown that the semi-circular lobes enhance the turbulent mixing and the shear layer growth rate. Hence, they significantly reduce the reattachment length by about 75%. The semi-circular lobes partially reduce undesired low-frequency pressure fluctuations on the nozzle surface. However, this reduction is achieved at the expense of an increase of high-frequency pressure fluctuations due to intensified small turbulent scales. The DMD analysis of the velocity field reveals that the large-scale coherent structures featuring a wave length of two step heights observed in the reference configuration without flow control can be suppressed by the lobes. The spanwise wave length of the coherent structures seems to depend on the geometry of the lobes, since all detected spatial DMD modes show a spanwise periodicity being equal to the distance between two lobes.
      PubDate: 2017-12-08
      DOI: 10.1007/s12567-017-0183-3
       
  • Fading characteristics of maritime propagation channel for beyond
           geometrical horizon communications in C-band
    • Authors: Wei Wang; Ronald Raulefs; Thomas Jost
      Abstract: The design of a maritime communication system requires the understanding of the wireless propagation channel above the sea. For broadband communication systems, a carrier frequency in the C-band is of interest because of allocatable spectrum. Therefore, the German Aerospace Center performed a long-distance channel measurement campaign at 5.2 GHz on the North sea to investigate large and small-scale fading characteristics. The results show that our measurement data conforms with the ITU-R and the Bullington’s path loss model to predict the power loss caused by diffraction over the Earth’s surface. Further, the first tap of the channel impulse response experiences Rician fading due to superposition of a strong line-of-sight (LoS) path and multipath components originating from the sea surface and ship body. We found that the fading of the second tap follows a Rician distribution, but with a much smaller K-factor compared to the first tap. The K-factor showed a dependence on the distance between the transmitter and receiver. Particularly, the K-factor of the first tap decreases significantly when the distance between the transmitter and receiver is larger than the clearance distance of the first Fresnel zone. Therefore, we propose a distance-dependent K-factor model for the first and the second tap.
      PubDate: 2017-12-04
      DOI: 10.1007/s12567-017-0185-1
       
  • Ka-band to L-band frequency down-conversion based on III–V-on-silicon
           photonic integrated circuits
    • Authors: K. Van Gasse; Z. Wang; S. Uvin; B. De Deckere; J. Mariën; L. Thomassen; G. Roelkens
      Abstract: In this work, we present the design, simulation and characterization of a frequency down-converter based on III–V-on-silicon photonic integrated circuit technology. We first demonstrate the concept using commercial discrete components, after which we demonstrate frequency conversion using an integrated mode-locked laser and integrated modulator. In our experiments, five channels in the Ka-band (27.5–30 GHz) with 500 MHz bandwidth are down-converted to the L-band (1.5 GHz). The breadboard demonstration shows a conversion efficiency of − 20 dB and a flat response over the 500 MHz bandwidth. The simulation of a fully integrated circuit indicates that a positive conversion gain can be obtained on a millimeter-sized photonic integrated circuit.
      PubDate: 2017-11-03
      DOI: 10.1007/s12567-017-0179-z
       
  • Space gravitational wave antenna DECIGO and B-DECIGO
    • Authors: Mitsuru Musha; DECIGO Working Group
      Abstract: Since the direct detection of gravitational wave will give us a fruitful insight about the early universe or life of stars, laser interferometric gravitational wave detectors with the strain sensitivity of higher than 10−22 have been developed. In Japan, the space gravitational wave detector project named DECi-hertz Gravitational wave Observatory (DECIGO) has been promoted which consists of three satellites forming equilateral triangle-shaped Fabry–Perot laser interferometer with the arm length of 1000 km. The designed strain sensitivity of DECIGO is 2 × 10−24/√Hz around 0.1 Hz whose targets are gravitational waves originated from the inspiral and the merger of black hole or neutron star binaries and from the inflation at the early universe, and no ground-based gravitational wave detector can access this observation band. Before launching DECIGO in 2030s, a milestone mission named B-DECIGO is planned which is a downsized mission of DECIGO. B-DECIGO also has its own scientific targets in addition to the feasibility test for DECIGO. In the present paper, DECIGO and B-DECIGO projects are reviewed.
      PubDate: 2017-11-02
      DOI: 10.1007/s12567-017-0177-1
       
 
 
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