An Investigation of Regression Rate of the Melting Interface for Iron Burning in Normal Gravity and Reduced Gravity

2008 ◽  
pp. 259-259-12
Author(s):  
NR Ward ◽  
T Suvorovs ◽  
TA Steinberg
Keyword(s):  
Normal Gravity ◽  
Reduced Gravity ◽  
Regression Rate

Effects of gravity on processing heavy metal fluoride fibers

1997 ◽  
Vol 12 (9) ◽  
pp. 2223-2225 ◽  
Author(s):  
Dennis S. Tucker ◽  
Gary L. Workman ◽  
Guy A. Smith
Keyword(s):  
Heavy Metal ◽  
Crystallization Temperature ◽  
Normal Gravity ◽  
Crystal Nucleation ◽  
Sounding Rocket ◽  
Metal Fluoride ◽  
Reduced Gravity ◽  
Rocket Flight ◽  
Heavy Metal Fluoride

The effects of gravity on the crystal nucleation of heavy metal fluoride fibers have been studied in preliminary experiments utilizing NASA's KC-135 reduced gravity aircraft and a microgravity sounding rocket flight. Commercially produced fibers were heated to the crystallization temperature in normal and reduced gravity. The fibers processed in normal gravity showed complete crystallization while the fibers processed in reduced gravity did not show signs of crystallization.

Airplane and Drop Experiments on Crystallization of InxGa1−xSb Semiconductor under Different Gravity Conditions

2001 ◽  
Vol 692 ◽  
Author(s):  
Krishnan Balakrishnan ◽  
Yasuhiro Hayakawa ◽  
Hideki Komatsu ◽  
Noriaki Murakami ◽  
Tetsuo Nakamura ◽  
...  
Keyword(s):  
Crystal Growth ◽  
High Speed ◽  
Normal Gravity ◽  
Ccd Camera ◽  
Reduced Gravity ◽  
Gravity Condition ◽  
Crystallization Experiments ◽  
Melting And Crystallization ◽  
Normal Gravity Condition

AbstractMelting and crystallization experiments of InGaSb were done under the reduced gravity condition (10−2G) in an airplane and at the normal gravity condition (1G) in the laboratory. Crystallized InGaSb was found to contain many needle crystals in both the cases. Reduced gravity condition was found to be more conducive for crystal growth than the normal gravity condition. Formation of spherical projections on the surface of InGaSb during its crystallization was in-situ observed using a high speed CCD camera in the drop experiment. Spherical projections showed dependence of gravity during its growth. Indium compositions in the spherical projections were found to vary depending on the temperature.

Exposure to reduced gravity impairs junctional transmission at the semicircular canal in the frog labyrinth

2010 ◽  
Vol 298 (2) ◽  
pp. R439-R452 ◽  
Author(s):  
Maria Lisa Rossi ◽  
Gemma Rubbini ◽  
Luciana Gioglio ◽  
Marta Martini ◽  
Riccardo Fesce
Keyword(s):  
Normal Gravity ◽  
Semicircular Canals ◽  
Sensory Epithelium ◽  
Reduced Gravity ◽  
Altered Gravity ◽  
Random Positioning Machine ◽  
Spike Discharge ◽  
Functional Changes ◽  
Afferent Fibers ◽  
Junctional Activity

The effects of microgravity on frog semicircular canals have been studied by electrophysiological and morphological approaches. Reduced gravity (microG) was simulated by a random positioning machine (RPM), which continually and randomly modified the orientation in space of the anesthetized animal. As this procedure stimulates the semicircular canals, the effect of altered gravity was isolated by comparing microG-treatment with an identical rotary stimulation in the presence of normal gravity (normoG). Electrophysiological experiments were performed in the isolated labyrinth, extracted from the animals after the treatment, and mounted on a turntable. Junctional activity was measured by recording quantal events (mEPSPs) and spikes from the afferent fibers close to the junction, at rest and during rotational stimulation. MicroG-treated animals displayed a marked decrease in the frequency of resting and evoked mEPSP discharge, vs. both control and normoG (mean decrease ∼50%). Spike discharge was also depressed: 57% of microG-treated frogs displayed no spikes at rest and during rotation at 0.1 Hz, vs. 23–31% of control or normoG frogs. Among the firing units, during one cycle of sinusoidal rotation at 0.1 Hz microG-treated units emitted an average of 41.8 ± 8.06 spikes, vs. 77.2 ± 8.19 in controls. Patch-clamp analysis on dissociated hair cells revealed altered Ca2+ handling, after microG, consistent with and supportive of the specificity of microG effects. Marked morphological signs of cellular suffering were observed after microG, mainly in the central part of the sensory epithelium. Functional changes due to microgravity were reversible within a few days.

scholarly journals Reducing gravity takes the bounce out of running

2017 ◽  
Author(s):  
Delyle T. Polet ◽  
Ryan T. Schroeder ◽  
John E. A. Bertram
Keyword(s):  
Stance Phase ◽  
Normal Gravity ◽  
Center Of Mass ◽  
Energetic Cost ◽  
Gravitational Acceleration ◽  
Reduced Gravity ◽  
Step Frequency ◽  
Energetic Costs ◽  
Gait Adaptation ◽  
Vertical Takeoff

AbstractIn gravity below Earth normal, a person should be able to take higher leaps in running. We asked ten subjects to run on a treadmill in five levels of simulated reduced gravity and optically tracked center of mass kinematics. Subjects consistentlyreducedballistic height compared to running in normal gravity. We explain this trend by considering the vertical takeoff velocity (defined as maximum vertical velocity). Energetically optimal gaits should balance energetic costs of ground-contact collisions (favouring lower takeoff velocity), and step frequency penalties such as leg swing work (favouring higher takeoff velocity, but less so in reduced gravity). Measured vertical takeoff velocity scaled with the square root of gravitational acceleration, following energetic optimality predictions and explaining why ballistic height decreases in lower gravity. The success of work-based costs in predicting this behaviour challenges the notion that gait adaptation in reduced gravity results from an unloading of the stance phase. Only the relationship between takeoff velocity and swing cost changes in reduced gravity; the energetic cost of the down-to-up transition for a given vertical takeoff velocity does not change with gravity. Because lower gravity allows an elongated swing phase for a given takeoff velocity, the motor control system can relax the vertical momentum change in the stance phase, so reducing ballistic height, without great energetic penalty to leg swing work. While it may seem counterintuitive, using less “bouncy” gaits in reduced gravity is a strategy to reduce energetic costs, to which humans seem extremely sensitive.Summary StatementDuring running, humans take higher leaps in normal gravity than in reduced gravity, in order to optimally balance the competing costs of stance and leg-swing work.

Hydrothermal waves on ethanol droplets evaporating under terrestrial and reduced gravity levels

2012 ◽  
Vol 712 ◽  
pp. 614-623 ◽  
Author(s):  
F. Carle ◽  
B. Sobac ◽  
D. Brutin
Keyword(s):  
Experimental Study ◽  
Normal Gravity ◽  
Scaling Law ◽  
Gravity Level ◽  
Reduced Gravity ◽  
Microgravity Conditions ◽  
Evaporation Dynamics ◽  
Good Agreement

AbstractThis experimental study, performed under microgravity conditions, focuses on the evaporation dynamics of ethanol drops and the formation and behaviour of the hydrothermal waves that spontaneously develop on the drop surfaces. The aim of this study is to compare our results to a similar study performed under normal gravity conditions to confirm the purely thermocapillary origin of these instabilities. A scaling law predicts with good agreement the number of instabilities that form, regardless of the gravity level.

Attachment to stainless steel by Mir Space Station bacteria growing under modeled reduced gravity at varying nutrient concentrations

Biofilms ◽  
2005 ◽  
Vol 2 (1) ◽  
pp. 1-7 ◽  
Author(s):  
P. W. Baker ◽  
L. G. Leff
Keyword(s):  
Stainless Steel ◽  
Biofilm Formation ◽  
Normal Gravity ◽  
Space Station ◽  
Water System ◽  
Planktonic Cell ◽  
Nutrient Concentrations ◽  
Reduced Gravity ◽  
Planktonic Cells ◽  
Cell Counts

Four bacterial isolates (Chryseobacterium sp., Pseudomonas fluorescens and two Stenotrophomonas maltophilia isolates) originally isolated from the water system aboard the Mir Space Station were grown in two concentrations of nutrient broth under modeled reduced gravity using clinorotation. Sampling was performed over a 7 day period and planktonic cells were enumerated using 4′,6-diamidino-2-phenylindole (DAPI), while those attached to stainless steel were enumerated using the LIVE/DEAD® BacLight™ kit and DAPI. On some of the sampling days for all the isolates, planktonic cell counts were higher under modeled reduced gravity as compared with the normal gravity controls. In contrast, the number of cells of P. fluorescens and one S. maltophilia isolate attached to the stainless steel disks was higher under modeled reduced gravity as compared with normal gravity, whereas no such differences were observed for Chryseobacterium sp. and the other S. maltophilia isolate. Differences in motility among isolates appeared to influence the growth of planktonic cells under modeled reduced gravity but did not appear to be related to biofilm formation.

scholarly journals Combustion of Methanol Droplets in Air-Diluent Environments with Reduced and Normal Gravity

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Benjamin Shaw ◽  
Jingbin Wei
Keyword(s):  
Carbon Dioxide ◽  
Normal Gravity ◽  
Size Range ◽  
Radiant Heat ◽  
Heat Output ◽  
Reduced Gravity ◽  
Fuel Type ◽  
Gas Transport Properties ◽  
Burning Rates ◽  
Combustion Behaviors

Reduced and normal gravity combustion experiments were performed with fiber-supported methanol droplets with initial diameters in the 1 mm size range. Experiments were performed with air-diluent mixtures at about 0.101 MPa and 298 K, where carbon dioxide, helium, or xenon was separately used as the diluent gas. Results indicate that ambient gas transport properties play an important role in determining flammability and combustion behaviors including burning rates and radiant heat output histories of the droplets. Droplets would burn with significantly higher mole fractions of xenon than helium or carbon dioxide. In reduced gravity, droplets would burn steadily with a xenon mole fraction of 0.50 but would not burn steadily if helium or carbon dioxide mole fractions were 0.50. Comparison with previous experimental data shows that ignitability and combustion characteristics of droplets are influenced by the fuel type and also the gravitational level. Burning rates were about 40% to 70% higher in normal gravity than in reduced gravity. Methanol droplets also had burning rates that were typically larger than 1-propanol burning rates by about 20% in reduced gravity. In normal gravity, however, burning rate differences between the two fuels were significantly smaller.

Heat Exchange and Condensation in Reduced Gravity

2004 ◽  
Author(s):  
Masood Parang ◽  
Viatcheslav Naumov
Keyword(s):  
Heat Exchange ◽  
Water Temperature ◽  
Normal Gravity ◽  
Water Flow Rate ◽  
Water Mixture ◽  
Reduced Gravity ◽  
Two Phase ◽  
University Of Tennessee ◽  
Small Water ◽  
Experimental Apparatus

The present investigation was sponsored by the NASA Reduced Gravity Student Flight Opportunity Program and was conducted by the University of Tennessee students aboard KC-135 in parabolic flights. The goal of the experiment was to study saturated air-water mixture to simulate the dynamics of condensation and heat exchange in two-phase flows and gain a better understanding of condensation under reduced gravity condition. In the experimental apparatus saturate air/water mixture is pumped through a one-inch cooled horizontal test pipe (condenser). Sets of thermocouples record change of temperature of liquid water, temperature of saturated air across the condenser, and temperature of liquid and fog after the test section. The water temperature measurements indicate lower water temperature and larger exit fog temperature at the condenser exit under reduced gravity as compared with normal gravity results. It was also observed that for relatively small water flow rate and velocity heat exchange between air and water streams was larger for reduced gravity conditions relative to normal gravity conditions.

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