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  Subjects -> MATHEMATICS (Total: 864 journals)
    - APPLIED MATHEMATICS (69 journals)
    - GEOMETRY AND TOPOLOGY (19 journals)
    - MATHEMATICS (642 journals)
    - MATHEMATICS (GENERAL) (40 journals)
    - NUMERICAL ANALYSIS (19 journals)
    - PROBABILITIES AND MATH STATISTICS (75 journals)

MATHEMATICS (642 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 538 Journals sorted alphabetically
Abakós     Open Access   (Followers: 4)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 2)
Academic Voices : A Multidisciplinary Journal     Open Access   (Followers: 2)
Accounting Perspectives     Full-text available via subscription   (Followers: 6)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 16)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 4)
ACM Transactions on Mathematical Software (TOMS)     Hybrid Journal   (Followers: 6)
ACS Applied Materials & Interfaces     Full-text available via subscription   (Followers: 21)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1)
Acta Mathematica     Hybrid Journal   (Followers: 10)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 5)
Acta Mathematica Vietnamica     Hybrid Journal  
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal  
Advanced Science Letters     Full-text available via subscription   (Followers: 5)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 3)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 15)
Advances in Decision Sciences     Open Access   (Followers: 4)
Advances in Difference Equations     Open Access   (Followers: 1)
Advances in Fixed Point Theory     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 9)
Advances in Linear Algebra & Matrix Theory     Open Access   (Followers: 1)
Advances in Materials Sciences     Open Access   (Followers: 16)
Advances in Mathematical Physics     Open Access   (Followers: 6)
Advances in Mathematics     Full-text available via subscription   (Followers: 10)
Advances in Numerical Analysis     Open Access   (Followers: 3)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Pure and Applied Mathematics     Hybrid Journal   (Followers: 5)
Advances in Pure Mathematics     Open Access   (Followers: 4)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2)
African Journal of Educational Studies in Mathematics and Sciences     Full-text available via subscription   (Followers: 5)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 4)
Afrika Matematika     Hybrid Journal   (Followers: 1)
Air, Soil & Water Research     Open Access   (Followers: 7)
AKSIOMA Journal of Mathematics Education     Open Access   (Followers: 1)
Algebra and Logic     Hybrid Journal   (Followers: 2)
Algebra Colloquium     Hybrid Journal   (Followers: 4)
Algebra Universalis     Hybrid Journal   (Followers: 2)
Algorithmic Operations Research     Full-text available via subscription   (Followers: 5)
Algorithms     Open Access   (Followers: 9)
Algorithms Research     Open Access   (Followers: 1)
American Journal of Biostatistics     Open Access   (Followers: 9)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 3)
American Journal of Mathematical Analysis     Open Access  
American Journal of Mathematics     Full-text available via subscription   (Followers: 7)
American Journal of Operations Research     Open Access   (Followers: 5)
American Mathematical Monthly     Full-text available via subscription   (Followers: 6)
An International Journal of Optimization and Control: Theories & Applications     Open Access   (Followers: 7)
Analele Universitatii Ovidius Constanta - Seria Matematica     Open Access   (Followers: 1)
Analysis     Hybrid Journal   (Followers: 2)
Analysis and Applications     Hybrid Journal   (Followers: 1)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 4)
Analysis Mathematica     Full-text available via subscription  
Annales Mathematicae Silesianae     Open Access  
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4)
Annales UMCS, Mathematica     Open Access   (Followers: 1)
Annales Universitatis Paedagogicae Cracoviensis. Studia Mathematica     Open Access  
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Data Science     Hybrid Journal   (Followers: 8)
Annals of Discrete Mathematics     Full-text available via subscription   (Followers: 6)
Annals of Mathematics     Full-text available via subscription  
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 6)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of the Alexandru Ioan Cuza University - Mathematics     Open Access  
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1)
Annals of West University of Timisoara - Mathematics     Open Access  
Annuaire du Collège de France     Open Access   (Followers: 5)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applications of Mathematics     Hybrid Journal   (Followers: 1)
Applied Categorical Structures     Hybrid Journal   (Followers: 2)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Mathematics     Open Access   (Followers: 3)
Applied Mathematics     Open Access   (Followers: 4)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 4)
Applied Mathematics - A Journal of Chinese Universities     Hybrid Journal  
Applied Mathematics Letters     Full-text available via subscription   (Followers: 1)
Applied Mathematics Research eXpress     Hybrid Journal   (Followers: 1)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arab Journal of Mathematical Sciences     Open Access   (Followers: 2)
Arabian Journal of Mathematics     Open Access   (Followers: 2)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 1)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 4)
Archive of Numerical Software     Open Access  
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
Arnold Mathematical Journal     Hybrid Journal   (Followers: 1)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 17)
Asia-Pacific Journal of Operational Research     Hybrid Journal   (Followers: 3)
Asian Journal of Algebra     Open Access   (Followers: 1)
Asian Journal of Current Engineering & Maths     Open Access  
Asian-European Journal of Mathematics     Hybrid Journal   (Followers: 2)
Australian Mathematics Teacher, The     Full-text available via subscription   (Followers: 7)
Australian Primary Mathematics Classroom     Full-text available via subscription   (Followers: 2)
Australian Senior Mathematics Journal     Full-text available via subscription   (Followers: 1)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Axioms     Open Access  
Baltic International Yearbook of Cognition, Logic and Communication     Open Access  
Basin Research     Hybrid Journal   (Followers: 3)
BIBECHANA     Open Access  
BIT Numerical Mathematics     Hybrid Journal  
BoEM - Boletim online de Educação Matemática     Open Access  
Boletim Cearense de Educação e História da Matemática     Open Access  
Boletim de Educação Matemática     Open Access  
Boletín de la Sociedad Matemática Mexicana     Hybrid Journal  
Bollettino dell'Unione Matematica Italiana     Full-text available via subscription   (Followers: 1)
British Journal of Mathematical and Statistical Psychology     Full-text available via subscription   (Followers: 19)
Bruno Pini Mathematical Analysis Seminar     Open Access  
Buletinul Academiei de Stiinte a Republicii Moldova. Matematica     Open Access   (Followers: 5)
Bulletin des Sciences Mathamatiques     Full-text available via subscription   (Followers: 4)
Bulletin of Dnipropetrovsk University. Series : Communications in Mathematical Modeling and Differential Equations Theory     Open Access   (Followers: 1)
Bulletin of Mathematical Sciences     Open Access   (Followers: 2)
Bulletin of the Brazilian Mathematical Society, New Series     Hybrid Journal  
Bulletin of the London Mathematical Society     Hybrid Journal   (Followers: 3)
Bulletin of the Malaysian Mathematical Sciences Society     Hybrid Journal  
Calculus of Variations and Partial Differential Equations     Hybrid Journal  
Canadian Journal of Science, Mathematics and Technology Education     Hybrid Journal   (Followers: 18)
Carpathian Mathematical Publications     Open Access   (Followers: 1)
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal  
CHANCE     Hybrid Journal   (Followers: 5)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Annals of Mathematics, Series B     Hybrid Journal  
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Mathematics     Open Access  
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Cogent Mathematics     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Collectanea Mathematica     Hybrid Journal  
College Mathematics Journal     Full-text available via subscription   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Commentarii Mathematici Helvetici     Hybrid Journal   (Followers: 1)
Communications in Contemporary Mathematics     Hybrid Journal  
Communications in Mathematical Physics     Hybrid Journal   (Followers: 1)
Communications On Pure & Applied Mathematics     Hybrid Journal   (Followers: 3)
Complex Analysis and its Synergies     Open Access   (Followers: 2)
Complex Variables and Elliptic Equations: An International Journal     Hybrid Journal  
Complexus     Full-text available via subscription  
Composite Materials Series     Full-text available via subscription   (Followers: 9)
Comptes Rendus Mathematique     Full-text available via subscription   (Followers: 1)
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 Complexity     Hybrid Journal   (Followers: 4)
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 4)
Computational Methods and Function Theory     Hybrid Journal  
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Concrete Operators     Open Access   (Followers: 4)
Confluentes Mathematici     Hybrid Journal  
COSMOS     Hybrid Journal  
Cryptography and Communications     Hybrid Journal   (Followers: 12)
Cuadernos de Investigación y Formación en Educación Matemática     Open Access  
Cubo. A Mathematical Journal     Open Access  
Czechoslovak Mathematical Journal     Hybrid Journal   (Followers: 1)
Demographic Research     Open Access   (Followers: 11)
Demonstratio Mathematica     Open Access  
Dependence Modeling     Open Access  
Design Journal : An International Journal for All Aspects of Design     Hybrid Journal   (Followers: 28)
Developments in Clay Science     Full-text available via subscription   (Followers: 1)
Developments in Mineral Processing     Full-text available via subscription   (Followers: 3)
Dhaka University Journal of Science     Open Access  
Differential Equations and Dynamical Systems     Hybrid Journal   (Followers: 2)
Discrete Mathematics     Hybrid Journal   (Followers: 7)
Discrete Mathematics & Theoretical Computer Science     Open Access  
Discrete Mathematics, Algorithms and Applications     Hybrid Journal   (Followers: 2)
Discussiones Mathematicae Graph Theory     Open Access   (Followers: 1)
Doklady Mathematics     Hybrid Journal  
Duke Mathematical Journal     Full-text available via subscription   (Followers: 1)
Edited Series on Advances in Nonlinear Science and Complexity     Full-text available via subscription  
Electronic Journal of Graph Theory and Applications     Open Access   (Followers: 2)
Electronic Notes in Discrete Mathematics     Full-text available via subscription   (Followers: 2)
Elemente der Mathematik     Full-text available via subscription   (Followers: 3)
Energy for Sustainable Development     Hybrid Journal   (Followers: 9)
Enseñanza de las Ciencias : Revista de Investigación y Experiencias Didácticas     Open Access  
Ensino da Matemática em Debate     Open Access  
Entropy     Open Access   (Followers: 4)
ESAIM: Control Optimisation and Calculus of Variations     Full-text available via subscription   (Followers: 1)
European Journal of Combinatorics     Full-text available via subscription   (Followers: 4)
European Journal of Mathematics     Hybrid Journal   (Followers: 1)
European Scientific Journal     Open Access   (Followers: 2)
Experimental Mathematics     Hybrid Journal   (Followers: 3)
Expositiones Mathematicae     Hybrid Journal   (Followers: 2)
Facta Universitatis, Series : Mathematics and Informatics     Open Access  
Fasciculi Mathematici     Open Access  
Finite Fields and Their Applications     Full-text available via subscription   (Followers: 4)
Fixed Point Theory and Applications     Open Access   (Followers: 1)
Formalized Mathematics     Open Access   (Followers: 2)
Foundations and Trends® in Econometrics     Full-text available via subscription   (Followers: 4)
Foundations and Trends® in Networking     Full-text available via subscription   (Followers: 1)

        1 2 3 4 | Last

Journal Cover CEAS Space Journal
  [SJR: 0.221]   [H-I: 5]   [0 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  [2341 journals]
  • Conceptual design of a crewed reusable space transportation system aimed
           at parabolic flights: stakeholder analysis, mission concept selection, and
           spacecraft architecture definition
    • Authors: Roberta Fusaro; Nicole Viola; Franco Fenoglio; Francesco Santoro
      Pages: 5 - 34
      Abstract: Abstract This paper proposes a methodology to derive architectures and operational concepts for future earth-to-orbit and sub-orbital transportation systems. In particular, at first, it describes the activity flow, methods, and tools leading to the generation of a wide range of alternative solutions to meet the established goal. Subsequently, the methodology allows selecting a small number of feasible options among which the optimal solution can be found. For the sake of clarity, the first part of the paper describes the methodology from a theoretical point of view, while the second part proposes the selection of mission concepts and of a proper transportation system aimed at sub-orbital parabolic flights. Starting from a detailed analysis of the stakeholders and their needs, the major objectives of the mission have been derived. Then, following a system engineering approach, functional analysis tools as well as concept of operations techniques allowed generating a very high number of possible ways to accomplish the envisaged goals. After a preliminary pruning activity, aimed at defining the feasibility of these concepts, more detailed analyses have been carried out. Going on through the procedure, the designer should move from qualitative to quantitative evaluations, and for this reason, to support the trade-off analysis, an ad-hoc built-in mission simulation software has been exploited. This support tool aims at estimating major mission drivers (mass, heat loads, manoeuverability, earth visibility, and volumetric efficiency) as well as proving the feasibility of the concepts. Other crucial and multi-domain mission drivers, such as complexity, innovation level, and safety have been evaluated through the other appropriate analyses. Eventually, one single mission concept has been selected and detailed in terms of layout, systems, and sub-systems, highlighting also logistic, safety, and maintainability aspects.
      PubDate: 2017-03-01
      DOI: 10.1007/s12567-016-0131-7
      Issue No: Vol. 9, No. 1 (2017)
       
  • A critical review of nanotechnologies for composite aerospace structures
    • Authors: Vassilis Kostopoulos; Athanasios Masouras; Athanasios Baltopoulos; Antonios Vavouliotis; George Sotiriadis; Laurent Pambaguian
      Pages: 35 - 57
      Abstract: Abstract The past decade extensive efforts have been invested in understanding the nano-scale and revealing the capabilities offered by nanotechnology products to structural materials. Integration of nano-particles into fiber composites concludes to multi-scale reinforced composites and has opened a new wide range of multi-functional materials in industry. In this direction, a variety of carbon based nano-fillers has been proposed and employed, individually or in combination in hybrid forms, to approach the desired performance. Nevertheless, a major issue faced lately more seriously due to the interest of industry is on how to incorporate these nano-species into the final composite structure through existing manufacturing processes and infrastructure. This interest originates from several industrial applications needs that request the development of new multi-functional materials which combine enhanced mechanical, electrical and thermal properties. In this work, an attempt is performed to review the most representative processes and related performances reported in literature and the experience obtained on nano-enabling technologies of fiber composite materials. This review focuses on the two main composite manufacturing technologies used by the aerospace industry; Prepreg/Autoclave and Resin Transfer technologies. It addresses several approaches for nano-enabling of composites for these two routes and reports latest achieved results focusing on performance of nano-enabled fiber reinforced composites extracted from literature. Finally, this review work identifies the gap between available nano-technology integration routes and the established industrial composite manufacturing techniques and the challenges to increase the Technology Readiness Level to reach the demands for aerospace industry applications.
      PubDate: 2017-03-01
      DOI: 10.1007/s12567-016-0123-7
      Issue No: Vol. 9, No. 1 (2017)
       
  • Influence of hydrogen temperature on the stability of a rocket engine
           combustor operated with hydrogen and oxygen
    • Authors: Stefan Gröning; Justin Hardi; Dmitry Suslov; Michael Oschwald
      Pages: 59 - 76
      Abstract: Abstract Since the late 1960s, low hydrogen injection temperature is known to have a destabilising effect on rocket engines with the propellant combination hydrogen/oxygen. Self-excited combustion instabilities of the first tangential mode have been found recently in a research rocket combustor operated with the propellant combination hydrogen/oxygen with a hydrogen temperature of 95 K. A hydrogen temperature ramping experiment has been performed with this research combustor to analyse the impact of hydrogen temperature on the self-excited combustion instabilities. The temperature was varied between 40 and 135 K. Contrary to past results found in literature, the combustor was found to be stable at low hydrogen temperatures while increased oscillation amplitudes of the first tangential mode were found at higher temperatures of around 100 K and above, which is consistent with previous observations of instabilities in this combustor. Further analysis shows that hydrogen temperature has a strong impact on the combustion chamber resonance frequencies. By varying the hydrogen injection temperature, the frequency of the first tangential mode is shifted to coincide with the second longitudinal resonance frequency of the liquid oxygen injector. Excitation of combustion chamber pressure oscillations was observed during such events.
      PubDate: 2017-03-01
      DOI: 10.1007/s12567-016-0130-8
      Issue No: Vol. 9, No. 1 (2017)
       
  • Beacons for supporting lunar landing navigation
    • Authors: Stephan Theil; Leonardo Bora
      Pages: 77 - 95
      Abstract: Abstract Current and future planetary exploration missions involve a landing on the target celestial body. Almost all of these landing missions are currently relying on a combination of inertial and optical sensor measurements to determine the current flight state with respect to the target body and the desired landing site. As soon as an infrastructure at the landing site exists, the requirements as well as conditions change for vehicles landing close to this existing infrastructure. This paper investigates the options for ground-based infrastructure supporting the onboard navigation system and analyzes the impact on the achievable navigation accuracy. For that purpose, the paper starts with an existing navigation architecture based on optical navigation and extends it with measurements to support navigation with ground infrastructure. A scenario of lunar landing is simulated and the provided functions of the ground infrastructure as well as the location with respect to the landing site are evaluated. The results are analyzed and discussed.
      PubDate: 2017-03-01
      DOI: 10.1007/s12567-016-0132-6
      Issue No: Vol. 9, No. 1 (2017)
       
  • Characterization of the supersonic wake of a generic space launcher
    • Authors: A.-M. Schreyer; S. Stephan; R. Radespiel
      Pages: 97 - 110
      Abstract: Abstract The wake flow of a generic axisymmetric space-launcher model is investigated experimentally for flow cases with and without propulsive jet to gain insight into the wake-flow phenomena at a supersonic stage of the flight trajectory which is especially critical with respect to dynamic loads on the structure. Measurements are performed at Mach 2.9 and a Reynolds number Re D  = 1.3 × 106 based on model diameter D. The nozzle exit velocity of the jet is at Mach 2.5, and the flow is moderately underexpanded (p e/p ∞ = 5.7). The flow topology is described based on velocity measurements in the wake by means of particle image velocimetry and schlieren visualizations. Mean and fluctuating mass-flux profiles are obtained from hot-wire measurements, and unsteady wall-pressure measurements on the main-body base are performed simultaneously. This way, the evolution of the wake flow and its spectral content can be observed along with the footprint of this highly dynamic flow on the launcher main-body base. For the case without propulsive jet, a large separated zone is forming downstream of the main body shoulder, and the flow is reattaching further downstream on the afterbody. The afterexpanding propulsive jet (air) causes a displacement of the shear layer away from the wall, preventing the reattachment of the flow. In the spectral analysis of the baseline case, a dominant frequency around St D  = 0.25 is found in the pressure-fluctuation signal at the main-body base of the launcher. This frequency is related to the shedding of the separation bubble and is less pronounced in the presence of the propulsive jet. In the shear layer itself, the spectra obtained from the hot-wire signal have a more broadband low-frequency content, which also reflects the characteristic frequency of turbulent structures convected in the shear layer, a swinging motion (St D  = 0.6), as well as the radial flapping motion of the shear layer (St D  = 0.85), respectively. Moving downstream along the shear layer, spectral content at slightly higher frequencies (St D  < 4) gets more pronounced and can be related to the shear layer instability process and the signature of smaller turbulent structures that appear in the wake.
      PubDate: 2017-03-01
      DOI: 10.1007/s12567-016-0134-4
      Issue No: Vol. 9, No. 1 (2017)
       
  • Green micro-resistojet research at Delft University of Technology: new
           options for Cubesat propulsion
    • Authors: A. Cervone; B. Zandbergen; D. C. Guerrieri; M. De Athayde Costa e Silva; I. Krusharev; H. van Zeijl
      Pages: 111 - 125
      Abstract: Abstract The aerospace industry is recently expressing a growing interest in green, safe and non-toxic propellants for the propulsion systems of the new generation of space vehicles, which is especially true in the case of Cubesat micro-propulsion systems. Demanding requirements are associated to the future missions and challenges offered by this class of spacecraft, where the availability of a propulsion system might open new possibilities for a wide range of applications including orbital maintenance and transfer, formation flying and attitude control. To accomplish these requirements, Delft University of Technology is currently developing two different concepts of water-propelled micro-thrusters based on MEMS technologies: a free molecular micro-resistojet operating with sublimating solid water (ice) at low plenum gas pressure of less than 600 Pa, and a more conventional micro-resistojet operating with liquid water heated and vaporized by means of a custom designed silicon heating chamber. In this status review paper, the current design and future expected developments of the two micro-propulsion concepts is presented and discussed, together with an initial analysis of the expected performance and potential operational issues. Results of numerical simulations conducted to optimize the design of the heating and expansion slots, as well as a detailed description of the manufacturing steps for the conventional micro-resistojet concept, are presented. Some intended steps for future research activities, including options for thrust intensity and direction control, are briefly introduced.
      PubDate: 2017-03-01
      DOI: 10.1007/s12567-016-0135-3
      Issue No: Vol. 9, No. 1 (2017)
       
  • Verification and validation of a parallel 3D direct simulation Monte Carlo
           solver for atmospheric entry applications
    • Authors: Paul Nizenkov; Peter Noeding; Martin Konopka; Stefanos Fasoulas
      Pages: 127 - 137
      Abstract: Abstract The in-house direct simulation Monte Carlo solver PICLas, which enables parallel, three-dimensional simulations of rarefied gas flows, is verified and validated. Theoretical aspects of the method and the employed schemes are briefly discussed. Considered cases include simple reservoir simulations and complex re-entry geometries, which were selected from literature and simulated with PICLas. First, the chemistry module is verified using simple numerical and analytical solutions. Second, simulation results of the rarefied gas flow around a \(70^{\circ }\) blunted-cone, the REX Free-Flyer as well as multiple points of the re-entry trajectory of the Orion capsule are presented in terms of drag and heat flux. A comparison to experimental measurements as well as other numerical results shows an excellent agreement across the different simulation cases. An outlook on future code development and applications is given.
      PubDate: 2017-03-01
      DOI: 10.1007/s12567-016-0133-5
      Issue No: Vol. 9, No. 1 (2017)
       
  • Exploratory numerical experiments with a macroscopic theory of interfacial
           interactions
    • Authors: D. Giordano; P. Solano-López; J. M. Donoso
      Abstract: Abstract Phenomenological theories of interfacial interactions are founded on the core idea to model macroscopically the thin layer that forms between media in contact as a two-dimensional continuum (surface phase or interface) characterised by physical properties per unit area; the temporal evolution of the latter is governed by surface balance equations whose set acts as bridging channel in between the governing equations of the volume phases. These theories have targeted terrestrial applications since long time and their exploitation has inspired our research programme to build up, on the same core idea, a macroscopic theory of gas–surface interactions targeting the complex phenomenology of hypersonic reentry flows as alternative to standard methods in aerothermodynamics based on accommodation coefficients. The objective of this paper is the description of methods employed and results achieved in the exploratory study that kicked off our research programme, that is, the unsteady heat transfer between two solids in contact in planar and cylindrical configurations with and without interface. It is a simple numerical-demonstrator test case designed to facilitate quick numerical calculations but, at the same time, to bring forth already sufficiently meaningful aspects relevant to thermal protection due to the formation of the interface. The paper begins with a brief introduction on the subject matter and a review of relevant literature within an aerothermodynamics perspective. Then the case is considered in which the interface is absent. The importance of tension (force per unit area) continuity as boundary condition on the same footing of heat-flux continuity is recognised and the role of the former in governing the establishment of the temperature-difference distribution over the separation surface is explicitly shown. Evidence is given that the standard temperature-continuity boundary condition is just a particular case. Subsequently the case in which the interface is formed between the solids is analysed. The coupling among the heat-transfer equations applicable in the solids and the balance equation for the surface thermodynamic energy more conveniently formulated in terms of the surface temperature is discussed. Results are illustrated and commented for planar and cylindrical configuration; they show unequivocally that the thermal-protection action of the interface turns out to be driven exclusively by thermophysical properties of the solids and of the interface; accommodation coefficients are not needed. Future work of more fluid-dynamics nature is mentioned in the concluding section.
      PubDate: 2017-04-10
      DOI: 10.1007/s12567-017-0148-6
       
  • Wavefront error measurement of the concave ellipsoidal mirrors of the
           METIS coronagraph on ESA Solar Orbiter mission
    • Authors: P. Sandri
      Abstract: Abstract The paper describes the alignment technique developed for the wavefront error measurement of ellipsoidal mirrors presenting a central hole. The achievement of a good alignment with a classic setup at the finite conjugates when mirrors are uncoated cannot be based on the identification and materialization at naked eye of the retro-reflected spot by the mirror under test as the intensity of the retro-reflected spot results to be ≈1E−3 of the intensity of the injected laser beam of the interferometer. We present the technique developed for the achievement of an accurate alignment in the setup at the finite conjugate even in condition of low intensity based on the use of an autocollimator adjustable in focus position and a small polished flat surface on the rear side of the mirror. The technique for the alignment has successfully been used for the optical test of the concave ellipsoidal mirrors of the METIS coronagraph of the ESA Solar Orbiter mission. The presented method results to be advantageous in terms of precision and of time saving also when the mirrors are reflective coated and integrated into their mechanical hardware.
      PubDate: 2017-04-09
      DOI: 10.1007/s12567-017-0150-z
       
  • 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
      Abstract: 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: 2017-04-07
      DOI: 10.1007/s12567-017-0149-5
       
  • A new method for optimization of low-thrust gravity-assist sequences
    • Authors: V. Maiwald
      Abstract: Abstract Recently missions like Hayabusa and Dawn have shown the relevance and benefits of low-thrust spacecraft concerning the exploration of our solar system. In general, the efficiency of low-thrust propulsion is one means of improving mission payload mass. At the same time, gravity-assist maneuvers can serve as mission enablers, as they have the capability to provide “free energy.” A combination of both, gravity-assist and low-thrust propulsion, has the potential to generally improve mission performance, i.e. planning and optimization of gravity-assist sequences for low-thrust missions is a desirable asset. Currently no established methods exist to include the gravity-assist partners as optimization variable for low-thrust missions. The present paper explains how gravity-assists are planned and optimized, including the gravity-assist partners, for high-thrust missions and discusses the possibility to transfer the established method, based on the Tisserand Criterion, to low-thrust missions. It is shown how the Tisserand Criterion needs to be adapted using a correction term for the low-thrust situation. It is explained why this necessary correction term excludes an a priori evaluation of sequences and therefore their planning and an alternate approach is proposed. Preliminary results of this method, by application of a Differential Evolution optimization algorithm, are presented and discussed, showing that the method is valid but can be improved. Two constraints on the search space are briefly presented for that aim.
      PubDate: 2017-02-28
      DOI: 10.1007/s12567-017-0147-7
       
  • Editorial
    • Authors: Hansjörg Dittus
      PubDate: 2017-02-09
      DOI: 10.1007/s12567-017-0146-8
       
  • Thanks to our Reviewers of the CEAS Space Journal
    • PubDate: 2017-01-31
      DOI: 10.1007/s12567-017-0144-x
       
  • Cooperative rendezvous between two spacecraft under finite thrust
    • Authors: Weiming Feng; Biao Wang; Kun Yang; Di Zhao
      Abstract: Abstract Dynamic equations of orbital elements of a modified vernal equinox for a far-distance cooperative rendezvous between two spacecraft were set up in this paper. The process of the far-distance cooperative rendezvous was optimized by a hybrid algorithm combining particle swarm optimization and differential evolution. The convergent costate vectors were obtained and set as the initial values of sequential quadratic programming to search for precise solutions, and the results proved to be stable and convergent. It can be seen from the results that the flight time of the cooperative rendezvous would be largely saved the amplitude of the thrust would be increased if the other conditions are fixed, and the fuel consumption would not be increased. However, the flight time would no longer decrease when the amplitude of the thrust reaches a certain value. In the last section of this paper, cooperative rendezvous and active–passive rendezvous were compared and analyzed, showing the advantages of cooperative rendezvous when the initial conditions are the same.
      PubDate: 2017-01-31
      DOI: 10.1007/s12567-017-0145-9
       
  • Numerical and experimental analysis of spallation phenomena
    • Authors: Alexandre Martin; Sean C. C. Bailey; Francesco Panerai; Raghava S. C. Davuluri; Huaibao Zhang; Alexander R. Vazsonyi; Zachary S. Lippay; Nagi N. Mansour; Jennifer A. Inman; Brett F. Bathel; Scott C. Splinter; Paul M. Danehy
      Pages: 229 - 236
      Abstract: Abstract The spallation phenomenon was studied through numerical analysis using a coupled Lagrangian particle tracking code and a hypersonic aerothermodynamics computational fluid dynamics solver. The results show that carbon emission from spalled particles results in a significant modification of the gas composition of the post-shock layer. Results from a test campaign at the NASA Langley HYMETS facility are presented. Using an automated image processing of short exposure images, two-dimensional velocity vectors of the spalled particles were calculated. In a 30-s test at 100 W/cm2 of cold-wall heat flux, more than 722 particles were detected, with an average velocity of 110 m/s.
      PubDate: 2016-12-01
      DOI: 10.1007/s12567-016-0118-4
      Issue No: Vol. 8, No. 4 (2016)
       
  • Analysis of the laser ignition of methane/oxygen mixtures in a sub-scale
           rocket combustion chamber
    • Authors: Michael Wohlhüter; Victor P. Zhukov; Joachim Sender; Stefan Schlechtriem
      Abstract: Abstract The laser ignition of methane/oxygen mixtures in a sub-scale rocket combustion chamber has been investigated numerically and experimentally. The ignition test case used in the present paper was generated during the In-Space Propulsion project (ISP-1), a project focused on the operation of propulsion systems in space, the handling of long idle periods between operations, and multiple reignitions under space conditions. Regarding the definition of the numerical simulation and the suitable domain for the current model, 2D and 3D simulations have been performed. Analysis shows that the usage of a 2D geometry is not suitable for this type of simulation, as the reduction of the geometry to a 2D domain significantly changes the conditions at the time of ignition and subsequently the flame development. The comparison of the numerical and experimental results shows a strong discrepancy in the pressure evolution and the combustion chamber pressure peak following the laser spark. The detailed analysis of the optical Schlieren and OH data leads to the conclusion that the pressure measurement system was not able to capture the strong pressure increase and the peak value in the combustion chamber during ignition. Although the timing in flame development following the laser spark is not captured appropriately, the 3D simulations reproduce the general ignition phenomena observed in the optical measurement systems, such as pressure evolution and injector flow characteristics.
      PubDate: 2016-12-27
      DOI: 10.1007/s12567-016-0143-3
       
  • Propulsive jet simulation with air and helium in launcher wake flows
    • Authors: Sören Stephan; Rolf Radespiel
      Abstract: Abstract The influence on the turbulent wake of a generic space launcher model due to the presence of an under-expanded jet is investigated experimentally. Wake flow phenomena represent a significant source of uncertainties in the design of a space launcher. Especially critical are dynamic loads on the structure. The wake flow is investigated at supersonic ( \(M=2.9\) ) and hypersonic ( \(M=5.9\) ) flow regimes. The jet flow is simulated using air and helium as working gas. Due to the lower molar mass of helium, higher jet velocities are realized, and therefore, velocity ratios similar to space launchers can be simulated. The degree of under-expansion of the jet is moderate for the supersonic case ( \(p_\mathrm{e}/p_\infty \approx 5\) ) and high for the hypersonic case ( \(p_\mathrm{e}/p_\infty \approx 90\) ). The flow topology is described by Schlieren visualization and mean-pressure measurements. Unsteady pressure measurements are performed to describe the dynamic wake flow. The influences of the under-expanded jet and different jet velocities are reported. On the base fluctuations at a Strouhal number, around \(\mathrm{St}_D \approx 0.25\) dominate for supersonic free-stream flows. With air jet, a fluctuation-level increase on the base is observed for Strouhal numbers above \(\mathrm{St}_D \approx 0.75\) in hypersonic flow regime. With helium jet, distinct peaks at higher frequencies are found. This is attributed to the interactions of wake flow and jet.
      PubDate: 2016-12-24
      DOI: 10.1007/s12567-016-0142-4
       
  • Erratum to: Verification and validation of a parallel 3D direct simulation
           Monte Carlo solver for atmospheric entry applications
    • Authors: Paul Nizenkov; Peter Noeding; Martin Konopka; Stefanos Fasoulas
      PubDate: 2016-11-22
      DOI: 10.1007/s12567-016-0141-5
       
  • Correction and adjusting for the deformation on solar sail
    • Authors: Fan Shen; Siyuan Rong; Hualan Zhang; Fujun Peng; Naigang Cui
      Abstract: Abstract A research on structural deformation of solar sail was presented. Nonlinear deformation of the sail was discussed, which will cause an additional devastating torque because of the shifting of the center of mass (CM). Finite-element analysis (FEA) method was carried out. In the computation, a correction was brought in, and a gradually increasing load method was presented. A more accurate membrane deformation result was obtained, and the photons pressure on the membrane was corrected. In purpose to guarantee the control ability in the long mission, a lifting mechanism is developed to adjust the large deformation. The lifting motion and result are verified by Abaqus. The research can be used in the solar sail controlling, where a large deformation may occur and an additional torque will disturb the controlling.
      PubDate: 2016-06-11
      DOI: 10.1007/s12567-016-0128-2
       
  • Transformable reflector structure with V-folding rods
    • Authors: Sh. Tserodze; J. Santiago Prowald; V. Gogilashvili; K. Chkhikvadze
      Abstract: Abstract A new design of space deployable reflector is presented. In particular, we consider closed-chain system (with central network), which as a result of transformation reaches the conical shape. In conformity with the technical specifications, individual parts of the system perform the simultaneous motion in the radial and axial directions. The main motion of the system produced by geometric constraints is studied, i.e., we consider the degree of structural motion. Parametric degrees of freedom caused by technological errors, modes of motion, types of load or deployment velocity are not taken into consideration at this stage. A peculiar feature of the deployable structure presented in the paper is that, as compared with analogous structures, for connecting the sections with one another there is no need of using synchronization devices in both—upper and lower kinematic chains simultaneously. This structural mechanism is a differential lever mechanism, the driving elements of which enable us to obtain the desired law of motion of every characteristic link. The kinematic model represents the whole system. Therefore, we can construct the function of position of the lever mechanism and also the kinematic functions of transmission. For the preliminary investigation of the structure and making possible changes in it, two mathematical models have been constructed by means of the ANSYS software using the Ansys Parametric Design Language. The degrees of freedom of the hinges are simulated in local coordinate systems and are as much as possible approximated to the real model. Calculations are performed for various kinds of loads and appropriate results are obtained.
      PubDate: 2016-06-01
      DOI: 10.1007/s12567-016-0125-5
       
 
 
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