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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 120 journals)
Showing 1 - 30 of 30 Journals sorted alphabetically
Acta Astronautica     Hybrid Journal   (Followers: 484)
Advances in Aerospace Engineering     Open Access   (Followers: 66)
Advances in Aerospace Science and Technology     Open Access   (Followers: 7)
Advances in Astronautics Science and Technology     Hybrid Journal  
Advances in Space Research     Full-text available via subscription   (Followers: 455)
Aeronautical Journal, The     Hybrid Journal   (Followers: 10)
Aerospace     Open Access   (Followers: 57)
Aerospace Medicine and Human Performance     Full-text available via subscription   (Followers: 14)
Aerospace Science and Technology     Hybrid Journal   (Followers: 423)
Aerospace Scientific Journal     Open Access   (Followers: 15)
Aerospace Systems     Hybrid Journal   (Followers: 3)
Aerospace technic and technology     Open Access   (Followers: 2)
Aerotecnica Missili & Spazio : Journal of Aerospace Science, Technologies & Systems     Hybrid Journal  
AIAA Journal     Hybrid Journal   (Followers: 1176)
Air Force Magazine     Full-text available via subscription   (Followers: 11)
Air Medical Journal     Hybrid Journal   (Followers: 8)
Annual of Navigation     Open Access   (Followers: 22)
Artificial Satellites     Open Access   (Followers: 23)
ASTRA Proceedings     Open Access   (Followers: 2)
Astrodynamics     Hybrid Journal   (Followers: 1)
Aviation     Open Access   (Followers: 15)
Aviation Advances & Maintenance     Open Access   (Followers: 3)
Aviation in Focus - Journal of Aeronautical Sciences     Open Access   (Followers: 10)
Aviation Psychology and Applied Human Factors     Hybrid Journal   (Followers: 26)
Aviation Week     Full-text available via subscription   (Followers: 438)
Canadian Aeronautics and Space Journal     Full-text available via subscription   (Followers: 33)
CEAS Aeronautical Journal     Hybrid Journal   (Followers: 29)
Chinese Journal of Aeronautics     Open Access   (Followers: 20)
Ciencia y Poder Aéreo     Open Access   (Followers: 2)
Civil Aviation High Technologies     Open Access   (Followers: 5)
Control Systems     Hybrid Journal   (Followers: 318)
Cosmic Research     Hybrid Journal   (Followers: 4)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 11)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 24)
Elsevier Astrodynamics Series     Full-text available via subscription   (Followers: 12)
Fatigue of Aircraft Structures     Open Access   (Followers: 15)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 12)
Gyroscopy and Navigation     Hybrid Journal   (Followers: 255)
IEEE Aerospace and Electronic Systems Magazine     Full-text available via subscription   (Followers: 277)
IEEE Journal on Miniaturization for Air and Space Systems     Hybrid Journal   (Followers: 2)
IEEE Transactions on Aerospace and Electronic Systems     Hybrid Journal   (Followers: 384)
IEEE Transactions on Circuits and Systems I: Regular Papers     Hybrid Journal   (Followers: 39)
International Journal of Aeroacoustics     Hybrid Journal   (Followers: 39)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 36)
International Journal of Aeronautical and Space Sciences     Hybrid Journal   (Followers: 2)
International Journal of Aerospace Engineering     Open Access   (Followers: 80)
International Journal of Aerospace Psychology     Hybrid Journal   (Followers: 23)
International Journal of Aerospace Sciences     Open Access   (Followers: 30)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 7)
International Journal of Aviation Management     Hybrid Journal   (Followers: 8)
International Journal of Aviation Technology, Engineering and Management     Full-text available via subscription   (Followers: 7)
International Journal of Aviation, Aeronautics, and Aerospace     Open Access   (Followers: 4)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 12)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 11)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 13)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 11)
International Journal of Space Structures     Full-text available via subscription   (Followers: 17)
International Journal of Space Technology Management and Innovation     Full-text available via subscription   (Followers: 10)
International Journal of Sustainable Aviation     Hybrid Journal   (Followers: 5)
International Journal of Turbo and Jet-Engines     Hybrid Journal   (Followers: 6)
Investigación Pecuaria     Open Access   (Followers: 3)
Journal of Aerodynamics     Open Access   (Followers: 17)
Journal of Aeronautical Materials     Open Access   (Followers: 9)
Journal of Aeronautics & Aerospace Engineering     Open Access   (Followers: 28)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 68)
Journal of Aerospace Engineering & Technology     Full-text available via subscription   (Followers: 16)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 20)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 32)
Journal of Aerospace Technology and Management     Open Access   (Followers: 7)
Journal of Aircraft     Hybrid Journal   (Followers: 338)
Journal of Aircraft and Spacecraft Technology     Open Access   (Followers: 8)
Journal of Airline and Airport Management     Open Access   (Followers: 12)
Journal of Astrobiology & Outreach     Open Access   (Followers: 3)
Journal of Aviation Technology and Engineering     Open Access   (Followers: 11)
Journal of Aviation/Aerospace Education & Research     Open Access   (Followers: 2)
Journal of Engineering and Technological Sciences     Open Access   (Followers: 1)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 205)
Journal of KONBiN     Open Access   (Followers: 3)
Journal of Navigation     Hybrid Journal   (Followers: 280)
Journal of Propulsion and Power     Hybrid Journal   (Followers: 609)
Journal of Space Safety Engineering     Hybrid Journal   (Followers: 7)
Journal of Space Weather and Space Climate     Open Access   (Followers: 27)
Journal of Spacecraft and Rockets     Hybrid Journal   (Followers: 771)
Journal of Spatial Science     Hybrid Journal   (Followers: 3)
Journal of the American Helicopter Society     Full-text available via subscription   (Followers: 7)
Journal of the Astronautical Sciences     Hybrid Journal   (Followers: 8)
Journal of the Australasian Society of Aerospace Medicine     Open Access   (Followers: 1)
Journal of Wind Engineering and Industrial Aerodynamics     Hybrid Journal   (Followers: 16)
Life Sciences in Space Research     Hybrid Journal   (Followers: 3)
MAD - Magazine of Aviation Development     Open Access   (Followers: 2)
Mekanika : Jurnal Teknik Mesin i     Open Access   (Followers: 1)
Microgravity Science and Technology     Hybrid Journal   (Followers: 2)
New Space     Hybrid Journal   (Followers: 6)
Nonlinear Dynamics     Hybrid Journal   (Followers: 19)
npj Microgravity     Open Access   (Followers: 3)
Open Aerospace Engineering Journal     Open Access   (Followers: 1)
Population Space and Place     Hybrid Journal   (Followers: 9)
Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering     Open Access   (Followers: 3)
Proceedings of the Human Factors and Ergonomics Society Annual Meeting     Hybrid Journal   (Followers: 16)
Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering     Hybrid Journal   (Followers: 45)
Progress in Aerospace Sciences     Full-text available via subscription   (Followers: 79)
Propulsion and Power Research     Open Access   (Followers: 67)
REACH - Reviews in Human Space Exploration     Full-text available via subscription   (Followers: 5)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 17)
RocketSTEM     Free   (Followers: 6)
Russian Aeronautics (Iz VUZ)     Hybrid Journal   (Followers: 24)
Science and Education : Scientific Publication of BMSTU     Open Access   (Followers: 1)
Space and Polity     Hybrid Journal   (Followers: 4)
Space Policy     Hybrid Journal   (Followers: 30)
Space Research Today     Full-text available via subscription   (Followers: 48)
Space Safety Magazine     Free   (Followers: 51)
Space Science International     Open Access   (Followers: 192)
Space Science Reviews     Hybrid Journal   (Followers: 97)
SpaceNews     Free   (Followers: 825)
Spatial Information Research     Hybrid Journal   (Followers: 1)
Technical Soaring     Full-text available via subscription   (Followers: 1)
Transport and Aerospace Engineering     Open Access   (Followers: 1)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 8)
Unmanned Systems     Hybrid Journal   (Followers: 5)
Вісник Національного Авіаційного Університету     Open Access   (Followers: 2)

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Similar Journals
Journal Cover
Microgravity Science and Technology
Journal Prestige (SJR): 0.514
Citation Impact (citeScore): 1
Number of Followers: 2  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0938-0108 - ISSN (Online) 1875-0494
Published by Springer-Verlag Homepage  [2626 journals]
  • Sensitivity of Plant Plasma Membrane to Simulated Microgravity
    • Abstract: Abstract Biological membranes, especially the plasma membrane, are considered to be the most sensitive to altered gravity in regard to their properties and functions. We studied the composition and content of lipids, fatty acids and sterols in the plasma membrane fractions isolated from epicotyls and roots of Pisum sativum seedlings grown during 7 days under simulated microgravity by slow clinorotation. We demonstrate differences in the content of these membrane components of clinorotated and 1 g controls. The results indicate the high sensitivity of root plasma membrane to altered gravity conditions.
      PubDate: 2021-01-14
       
  • Numerical Study on the Heat Transfer Characteristics of Axially Grooved
           Heat Pipe Assisted by Gravity
    • Abstract: Abstract The theoretical model of the evaporation and condensation heat transfer process of the axially grooved heat pipe (AGHP) assisted by gravity under small angle inclination is established to investigate the evaporation regimes and the heat transfer characteristics of AGHP. To reveal the heat transfer mechanism of the AGHP, the working state and gas-liquid interface distribution of the AGHP with different input power are analysed. And the influence of the inclination angle and groove structure (length-width ratio), including on the maximum heat transfer of AGHP is also discussed. The numerical simulations indicate that: With the increasing input power, the fin-film evaporation regime transits to the corner-film evaporation regime in the AGHP. The growing inclination angle enhances the gravitational effect on the liquid reflux and increases the critical input power for the evaporation regime transition. As the aspect ratio of the grooves increase, the increasing maximum radius of the meniscus leads to stronger heat transfer capacity of the AGHP.
      PubDate: 2021-01-13
       
  • Mechanisms of the Effect of Simulated Microgravity on the Cytotoxicity of
           NK Cells Following the DNA Methylation of NKG2D and the Expression of
           DAP10
    • Abstract: Abstract The inhibition of the cytotoxicity of NK cells by microgravity in space is of serious concern to the health of astronauts. However, there remains a lack of in-depth research into the mechanisms of action of this suppression. In the present study, the effects of simulated microgravity (SMG) on the morphology, survival rate and the ability of NK cells to kill were studied initially and then the mechanism of SMG in the inhibition of NK cytotoxicity was preliminarily investigated from the perspectives of stimulatory and inhibitory receptor expression. Further, the present study attempted to reveal the molecular mechanisms of SMG inhibition of the stimulatory receptor NKG2D from the perspective of DNA methylation and the expression of its adaptor protein DAP10. The results demonstrated that down-regulation of stimulatory receptor NKG2D expression and significantly up-regulated expression of inhibitory receptor CD158a may be important in explaining for the inhibition of NK cell cytotoxicity by SMG. The down-regulation of DAP10 expression, and not its DNA methylation, that is the possible cause of the down-regulation of NKG2D expression by SMG and the subsequent suppression of NK cell activity. However, inhibition of DAP10 expression by SMG was also not achieved by influencing methylation, and so additional analysis of the mechanism is required. The results of the present study lay the foundations for finally elucidating the molecular mechanisms by which microgravity leads to a decline in NK cell activity and contributes important evidence for interpreting the regulatory mechanisms of NK cell cytotoxicity.
      PubDate: 2021-01-07
       
  • Thermal Performance of an Axially Grooved Heat Pipe Subjected to Multiple
           Heating Sources
    • Abstract: Abstract An experiment of axial temperature test for a heat pipe subjected to discrete heating sources is performed for deep understanding of the thermal characteristics of axial dovetail grooved heat pipe during the unsteady and steady state. The influences of heating length, heating source position, source configurations and incline angle on the temperature profiles, heat transfer limit of the heat pipe under single heating source and multiple heating sources are examined and analyzed. As can be seen from the experiment results, the heating source shows a pivotal role in the transient characteristics of the dovetail grooved heat pipe. The heated zone of the heat pipe shows higher temperature level than that of the non-heated zone, and there is a sharp temperature variation at the transition region of the heating zone and non-heating zone. When heat is imposed at the front end of heat pipe, a dramatic increase of temperature appears soon after the heating power has reached its heat transport limitation. And this limitation can still be increased when the heating source is imposed close to the cooling section as the distance between the heating source and the cooling section decreases. Increase of heating length narrows the gap of the temperature between evaporator section and condenser section, and hence lead to lower thermal resistance, higher thermal conductivity, and superior heat transport performance. Owing to the gravity assistance on the backflow fluid in microgrooves, better thermal performance can be observed when the heat pipe works under incline state than that under horizontal state.
      PubDate: 2021-01-07
       
  • Steady thermocapillary droplet migration under thermal radiation with a
           uniform flux
    • Abstract: Abstract Thermocapillary migration of a droplet under thermal radiation with a uniform flux is numerically investigated and theoretically analyzed. By using the front-tracking method, it is observed that thermocapillary droplet migration at small Reynolds numbers and moderate Marangoni numbers reaches a steady process. The steady migration velocity decreases as Marangoni number increases. The time-evolution behavior of temperature fields in the steady migration process is found to be a quadratic function, in which the linear rise of the steady state temperatures with the relative time is a main characteristics. The quadratic function behavior of the temperature fields is further used to derive the steady energy equations. From the steady momentum and energy equations, an analytical result at small Reynolds number and zero Marangoni number is determined by using the method of matched asymptotic expansions. The steady migration velocity decreases as Reynolds number increases, which is in qualitatively agreement with the numerical result.
      PubDate: 2021-01-07
       
  • Multi-Position Calibration Method of Gyroscopes in Inertial Measurement
           Unit Based on Centrifuge with Position Platform
    • Abstract: Abstract In order to accurately calibrate the static error model coefficients of three gyroscopes simultaneously, especially the higher-order coefficients, in an inertial measurement unit, an optimal 16-position method is designed. Analysis is conducted using a precision centrifuge with a counter-rotating platform, and coordinate systems are established on centrifuge. Thus, centrifuge error sources, which may affect the calibration accuracy of a gyroscope’s drift coefficients, are analyzed, corresponding to the coordinate systems established. Precise expressions for the input angular rate and the input specific forces on each axis of the three gyroscopes are derived using a homogeneous transformation method. The influence of centrifuge error on the drift coefficients is analyzed, and the calibration accuracy can be improved by compensating for the influence of centrifuge error. The 16-position calibration method is validated through simulation, which establishes that centrifuge errors such as Δθy2t, Δθy2(−Ωt), Δθx2t, Δθx2(−Ωt), and ΔΩ mainly influences the bias MF and first-order drift coefficients MI and MS, but has little impact on higher-order coefficients. The calibration process is simple and short time-consuming, and the calibration accuracy is satisfied to requirement. After compensating for the main centrifuge errors, the 16-position method will further increase the accuracy of an inertial navigation system.
      PubDate: 2021-01-07
       
  • Selective Transport of Airborne Microparticles Through Micro-channels
           Under Microgravity
    • Abstract: Abstract This paper analyzes the possibility of obtaining the selective transport of microparticles suspended in air in a microgravity environment through modulated channels without net displacement of air. Using numerical simulation and bifurcation analysis tools, we show the existence of intermittent particle drift under the Stokes assumption of the fluid flow. The particle transport can be selective and the direction of transport is controlled only by the kind of pumping used. The selective transport is interpreted as a deterministic ratchet effect due to spatial variations in the flow and the particle drag. This ratchet phenomenon could be applied to the selective transport of metal particles during the short duration of microgravity experiments.
      PubDate: 2021-01-05
       
  • A Solute Flux Near a Solid Wall as a Reason for the Observation of
           Anomalous Transport
    • Abstract: Abstract The paper is devoted to the study of the reasons of anomalous transport observation in the experiments with microchannels. Usually, retardation of such transport is associated with the interaction of solute particles with channel walls. In the present paper, we have shown that the viscous interaction of the flow and solid wall can be the reason for the anomalous transport observation. It was illustrated on a specific example of a passive solute transport through the channel. The effect of diffusion on such transport was investigated numerically. The power law decline of concentration with respect to time was obtained in a wide range of parameters.
      PubDate: 2021-01-05
       
  • Sensitivity Modeling and Enhancement for Space-Based Gravitational Wave
           Detector with Optical Atomic Clocks under Solar Radiation Disturbance
    • Abstract: Abstract The space-based gravitational wave detectors at low frequencies has received great attention recently. Due to lack of considering the relative motion between spacecrafts, the accuracy of current sensitivity models is inadequate for space-based gravitational wave detectors. In this paper, an accurate sensitivity model of the space-based gravitational wave detector is established by taking into account the relative motion between two spacecrafts. The accurate sensitivity model is derived by employing a gravitational wave perturbed metric tensor. Then, to minimize the sensitivity loss due to the solar radiation, an enhancement strategy is proposed. Finally, simulation studies are presented with two drag-free spacecrafts in Earth’s orbit. Simulation results validate the effectiveness of the proposed strategy.
      PubDate: 2021-01-04
       
  • Analysis of Noisy Radiometer Data from ISS Reduced Gravity Droplet
           Combustion Experiments
    • Abstract: Abstract Reduced gravity droplet combustion experiments were performed on the International Space Station (ISS). The data from these droplet combustion experiments have been made publicly available by NASA. These experiments utilized narrow-band and wide-band radiometers to measure thermal radiation heat fluxes from flames. The initial set of radiometers, which were used in 80 experiments, exhibited large noise levels, making interpretation of data from these experiments difficult. The noisy radiometers were replaced by NASA with a second set of radiometers that had significantly less noise. The work presented here is focused on: (1) evaluating methods to “denoise” the data from the initial (noisy) set of radiometers with a goal of detecting flame oscillations; and (2) making these denoising methods available to other researchers who would like to analyze the noisy radiometer data. The denoising efforts employed local polynomial regression analysis with a Gaussian kernel as well as frequency-based low-pass filters. Windowed Fourier transform and wavelet transform approaches were also employed to detect flame oscillations in radiometer data. Comparison of results from these approaches showed that local polynomial analyses and also wavelet transforms can detect the presence of flame oscillations in noisy radiometer data. Uncertainties in the noisy radiometer data were evaluated using a Monte Carlo bootstrapping approach.
      PubDate: 2021-01-04
       
  • Surface Properties of Liquid Al-Ni Alloys: Experiments Vs Theory
    • Abstract: Abstract The present study is an overview of the surface properties of liquid Al-Ni alloys, which are of great importance for the design and development of new Al-Ni and Ni-based industrial alloys, widely used as functional and structural materials. The solidification and thus, the microstructural evolution are directly dependent on the interface/surface properties of metallic melts. Therefore, numerical simulation of microstructure evolution requires reliable property data as input to such models. Taking into account the experimental difficulties related to a high reactivity of liquid Al-Ni alloys and the effects of impurities on their surface properties, the surface tension over the whole concentration range has been determined in the frameworks of three international research projects. Namely, the surface tension measurements have been carried out by both traditional container-based and as an alternative, containerless methods within the ESA-MAP ThermoProp and ESA-MAP Thermolab Projects and also under the EU FP6-IMPRESS Project. The obtained datasets were analysed and subsequently compared with the model predicted values as well as with the literature data. A strong exothermic mixing characterises the Al-Ni system and the presence of a few intermetallic compounds in the solid state leads to the formation of short range ordered elements or complexes in the liquid phase, at least near the melting temperature, which significantly affects the surface properties of alloy melts. Aiming to estimate the effects of short range ordering on these properties, the Compound Formation Model (CFM) and the Quasi Chemical Approximation (QCA) for regular solution were applied.
      PubDate: 2020-12-01
       
  • A Similarity Solution for Natural Convection Flow near a Vertical Plate
           with Thermal Radiation
    • Abstract: Abstract This paper examined the fluid transport on boundary layer near a vertical wall with thermal radiation effect. The coupled nonlinear partial differential equations are reduced to a system of ordinary differential equations through similarity transformation. The resultant system of ordinary differential equations is integrated with maple software using RKF45 method. The effect of the active parameters such as Grashof number, thermal radiation parameter, temperature difference, Prandtl number, and local convective heat transfer parameter on the velocity profile, skin friction, temperature profile and Nusselt number are presented using graphs and tables. The outcome of the study revealed that the Prandtl number has a decreasing effect on thermal boundary layer thickness. It also revealed that the thermal radiation has an increasing effect on the Nusselt number, temperature distribution, temperature gradient and skin friction. The temperature distribution increases with increasing values of the temperature difference and local convective heat transfer parameter whereas decreases with Grashof number.
      PubDate: 2020-12-01
       
  • Cross Diffusion and Internal Heat Generation Effects on Mixed Convection
           of Non-Newtonian Fluids Flow Adjacent to a Vertical VHF/VMF Wedge in
           Porous Media: the Entire Regime
    • Abstract: Abstract The problem of cross diffusion (Soret/Dufour) and internal heat generation effects on combined convection flow of non-Newtonian fluids flow over the vertical wedge in a saturated porous medium with the entire regime is solved numerically. The internal heat generation is assumed to be an exponential decaying form. The power law model of Ostwald-de-Waele for non-Newtonian fluids is considered here. The entire regime of the combined convection is included, as the combined convection parameter varies from 0 (pure free convection) to 1 (pure forced convection). The transformed equations are obtained by using a suitable coordinate transformation and then Keller box method (KBM) is utilized to solve the non-similar equations for the variable heat flux and variable mass flux (VHF/VMF) conditions. Comparisons with the previously published article are performed and the good agreement is achieved. The main numerical results for the dimensionless temperature and concentration distributions, the local Nusselt and Sherwood numbers are obtained.
      PubDate: 2020-12-01
       
  • Onset of Rayleigh-Benard Convection with Periodic Boundary Temperatures
           Using Weakly Nonlinear Theory
    • Abstract: Abstract This paper investigates the Rayleigh Benard instability of a viscous, Newtonian, Boussinesq fluid with time-periodic boundary temperature modulation using the framework of weakly nonlinear theory. Critical Rayleigh number is computed for asymptotic stability criterion using the energy method accompanied by variational algorithm. Subcritical instability is found to occur under two conditions: when modulation is in anti-phase and when modulation is imposed only on the lower boundary. Supercritical stability is witnessed during in-phase modulation. In all the three cases of the relative phase of two boundary temperatures, the effect of modulation is found to be weaker for infinitesimal disturbances. The findings of the present study could be referred in several applications where appropriate temperature modulation is of prime concern.
      PubDate: 2020-11-09
       
  • Phase Separation in Porous Media Integrated Capillary Channels
    • Abstract: Abstract Phase separation in space is critical for gas-free propellant supply, life support systems, refueling of spacecraft in low earth orbit (LEO), and for deep space exploration missions. In the absence of gravity, the stability of the liquid-gas interface depends on capillary forces. High liquid flow rates, sudden accelerations, and vibrational disturbances can cause the free surface of the liquid to collapse, which results in the ingestion of gas. Propellant tanks may have screen channel liquid acquisition devices (SCLADs) to position and maintain a gas-free propellant supply to the outlet. A saturated porous screen permits liquid to pass through but acts as a barrier to the gas. We investigated phase separation in porous media integrated capillary channels during parabolic flights (33rd DLR parabolic flight campaign in March 2019). An open side of a rectangular channel was covered with a dutch twill weave 200×1400. The liquid was ingested into the channel from its surroundings by establishing a differential pressure across the screen section. The gas-phase was blocked during the liquid withdrawal. We could show that the gas breakthrough occurs when the pressure difference across the screen exceeds the bubble point pressure. The experimental results showed good agreement with correlations from literature.
      PubDate: 2020-11-09
       
  • Thermodiffusion in Electrolyte Between Electric Membranes Under External
           Electric Field
    • Abstract: Abstract Thermodiffusion of a binary electrolyte situated in the microgap between two ion-selective surfaces under external electric field is theoretically studied. It is assumed that temperature gradient occurs only by Joule heating of the electrolyte; and the concentration gradient may trigger an inner gravitational instability. There are three types of instability in such setup: electrokinetic, thermoelectrokinetic and internal gravitational instability. The direct numerical simulation of the problem shows that for the typical salts solutions such as NaCl or KCl the termodiffusion effect is negligible, while for some salts with bigger values of the reduced Soret coefficients of ions (for example, for tetra-n-butylammonium fluoride) the thermodiffusion may significantly affect the voltage-current characteristic. It is also obtained, that the negative thermodiffusion leads to the destabilization of the one-dimensional steady state regime and shifts the critical values of governing parameters for each aforementioned type of instability. The thermodiffusion mostly influences the classical electrokinetic instability and less — the internal gravitational instability. Under effect of both types of thermodiffusion (normal and negative), the thermoelectrokinetic instability manifests at smaller values of Rayleigh numbers.
      PubDate: 2020-11-02
       
  • Quasi-Adiabatic External State Preparation of Ultracold Atoms in
           Microgravity
    • Abstract: Abstract The Cold Atom Laboratory on the International Space Station produces ultracold gases of rubidium and potassium in a tight magnetic trap near the surface of a magnetic chip. In order to use these samples in long-duration field-free experiments, the atoms must be moved away from the chip, expanded to larger volume, and released from the trap. We describe how these goals can be achieved using quasi-adiabatic techniques. For rubidium atoms, we demonstrate a displacement of 0.6 mm and expansion into a trap with a mean oscillation frequency of 6.4 Hz. The center-of-mass release velocity and the condensate expansion velocity are about 0.2 mm/s each. An unexpectedly large background magnetic field gradient is observed, which limits the usable interaction time for the released atoms.
      PubDate: 2020-10-21
       
  • Acoustic Manipulation of Dense Nanorods in Microgravity
    • Abstract: Abstract Because the absence of sedimentation in zero-gravity makes the culture and the manipulation of cells or particles challenging, an attractive alternative is to use the Acoustic Radiation Force (ARF) as an artificial “acoustic gravity.” To evaluate the potential of this approach we studied the behavior of dense gold nanorods under ARF during a parabolic flight campaign. Using dense objects enhances the effect of gravity on the axial position of the so-called “levitation plane,” which is the equilibrium position at which ARF balances gravity in the laboratory. Further, using elongated objects, instead of spherical particles provides information about their spatial orientations in addition to their propulsion observed in standard gravity conditions. Our experiments clearly show a different collective organization and individual behavior of the rods in micro-gravity conditions. First, the axial location of the levitation plane is different in microgravity than in hypergravity: it matches the nodal pressure plane in microgravity while it is much lower than the nodal plane in hypergravity. Our experiments also show a sharp transition from horizontal to axial orientation of the rods axis. The propulsion of the rods also stops when transitioning to micro-gravity. A possible explanation for the sudden change of orientation and stopping of propulsion is the modification of the equilibrium between the axial and transverse components of the ARF. While these experiments show that some phenomena, like the propulsion of nanorods by ARF, may not be applicable in microgravity, they do confirm that acoustic manipulation of particles or cells in microgravity is possible, which paves for the development of many useful techniques for particles or cells manipulation, like cell cultures, during long-term space travel.
      PubDate: 2020-10-19
       
  • The FixBox: Hardware to Provide on-Orbit Fixation Capabilities to the EMCS
           on the ISS
    • Abstract: Abstract Plant biology is an important area for the future of space exploration, but biological spaceflight experiments have been always constrained by the hardware capabilities. The European Modular Cultivation System (EMCS) unit was an incubator for small organisms, such as Arabidopsis thaliana, built by the European Space Agency (ESA) and was decommissioned in 2018. Here, we describe the FixBox system as add-on hardware to provide fixation capabilities to the plant growth cassettes, which, initially, were not designed to be used for that purpose. Tests were performed to ensure the successful use of this device in the EMCS facility. We also evaluate the required adaptations to the hardware, e.g., to guarantee that the reduced fluid motion in microgravity does not cause any bubbles that could impair the quality of fixation. Arabidopsis thaliana seedlings grown during spaceflight were fixed in the FixBox either in glutaraldehyde or formaldehyde. Electron microscopical images and confocal microscopy immunofluorescent localizations showed an excellent preservation of both cell ultrastructure and antigen conformation. Thus, it is possible to modify existing hardware to comply with the scientific requirements to augment the existing capabilities on board the ISS. In addition, it is also possible to reuse culture chambers from predesigned experimental containers into new modular subunits as FixBox. Similarly, we can design new hardware compatible with a novel cultivation chamber on board, such as is available in BIOLAB, to be used later with FixBox. Lessons learned for future space plant biology researchers include how to manage the number of hardware requirements and constraints on how to preserve the biological samples.
      PubDate: 2020-10-06
       
  • Drop Tower Experiment to Study the Effect of Microgravity on Friction
           Behavior: Experimental Set-up and Preliminary Results
    • Abstract: Abstract This paper refers to studying the effect of microgravity on the friction behavior of friction units and to further analyzing the influencing mechanism. The potential factors affecting the friction behavior of the moving joints of space mechanisms in microgravity environment were analyzed. A friction apparatus was designed and manufactured by reducing the complexity and costs. A microgravity test program was designed and performed using the Beijing Drop Tower platform with designing three positioning styles for the friction apparatus by changing the relationship between the normal load and gravity. For each positioning style of the friction apparatus, the friction behavior of friction unit in gravity and microgravity environment was compared. It was found that microgravity can not only change the value of friction, but also affect its dynamic characteristics. For different positioning styles of the friction apparatus, the influencing mechanism of microgravity on friction behavior was different. The normal load or the relative position between the connected bodies of the friction unit could be changed by microgravity, resulting in that the friction behavior was different from that in gravity environment.
      PubDate: 2020-10-04
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
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