Studies of upper atmosphere motions by VHF backscatter
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Bowhill, S. A.↗
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Experimental studies in vortex pair motion coincident with a liquid reaction
An experimental examination of the coincidence of a liquid reaction (acid/base) with the formation of a vortex pair structure is described in which emphasis is placed on the evolution of the strained diffusion layer and reacted core structures. Flow visualization of the reaction process is achieved via the technique of chemically sensitive LIF. The observed growth of reacted core structures associated with each vortex is compared with theoretically predicted behavior (Marble, 1983; Karagozian and Marble, 1986). Vortex pair separation is also compared with theoretical correlations, and the relevance of the analogy between a fast liquid reaction and a gaseous reaction is discussed.
Karagozian, A. R.↗
A study of satellite motion-induced multipath phenomena
Experiments have been undertaken at COMSAT Laboratories to determine some of the propagation effects likely to be encountered by handheld satellite communications devices. L-band pilot tones aboard geosynchronous satellites at 15 and 40 deg. elevations were used to examine diurnal signal variations measured by using a hemispherical antenna. It was found that the receiver with a hemispherical antenna suffered daily peak-to-peak signal level variations of up to 12 dB compared to only 2 to 3 dB for a receiver equipped with a directional antenna. These results were highly repeatable, and extensive tests were conducted to confirm the accuracy of the data. The results suggest that the diurnal variations were due to multipath effects caused by the motion of the satellite with respect to the receiver antenna. Noting that the orbit inclinations of the satellites used in the experiment were only on the order of 2 to 3 deg., the results also suggest a potentially serious signal variation problem for low-gain antenna-based communications systems using low earth orbit satellites, since the satellite elevation angles relative to earth change far more rapidly.
Allnutt, R. M.↗
A Theoretical Study of the Angular Motions of Spinning Bodies in Space
Euler's dynamic equations were linearized and solved analytically. Analytical expressions which relate angular motions to spin-rate and inertia distributions were obtained and found to be in good agreement with machine solutions of the nonlinear equations for the case of a rectangular-pulse pitching-moment disturbance. Consideration was given to the effects produced by having artificial damping in the system.
Suddath, Jerrold H.↗
Photographic study of condensing mercury flow in 0-G and 1-G environments
High speed motion picture study of condensing mercury vapor in glass tubes in ground and zero gravity test facilities
MERCURY VAPOR↗
Modeling Attitude Dynamics in Simulink: A Study of the Rotational and Translational Motion of a Spacecraft Given Torques and Impulses Generated by RMS Hand Controllers
In order to study and control the attitude of a spacecraft, it is necessary to understand the natural motion of a body in orbit. Assuming a spacecraft to be a rigid body, dynamics describes the complete motion of the vehicle by the translational and rotational motion of the body. The Simulink Attitude Analysis Model applies the equations of rigid body motion to the study of a spacecraft?s attitude in orbit. Using a TCP/IP connection, Matlab reads the values of the Remote Manipulator System (RMS) hand controllers and passes them to Simulink as specified torque and impulse profiles. Simulink then uses the governing kinematic and dynamic equations of a rigid body in low earth orbit (LE0) to plot the attitude response of a spacecraft for five seconds given known applied torques and impulses, and constant principal moments of inertia.
Mauldin, Rebecca H.↗
Contributions of the space program to our knowledge of motion sickness.
A slow rotation room (SRR) was used in a laboratory setting to study experimental motion sickness. This SRR simulates, to some degree, the conditions on a rotating spacecraft. Habitability of the chamber was ascertained by subjects who remained in the room for over a month with experimenters in attendance. Control over stressful accelerations involved regulation of the room's angular velocity and the subject's head rotations. By standardizing the head rotations, the strength of the disturbing stimulus became a function of the room's angular velocity. Mild acute episodes of motion sickness were readily kept under control. Certain techniques demonstrated that a subject's susceptibility may be expressed in terms of the number of head motions at a particular angular velocity to reach a chosen endpoint. Investigations using prolonged exposure used rapid increase in rpm to terminal velocity to evoke symptoms, or incremental increase to terminal velocity to prevent them. The effectiveness of 16 representative antimotion sickness drugs is discussed.
Graybiel, A.↗
Research on development of equations for performance trajectory computations
The analytical foundation of the Hamilton-Jacobi theory was investigated for application to space flight problems. A specific problem area is defined as follows: (1) to attempt to use the first order perturbation theory, which has been developed for the motion of a uniaxial satellite in a gravitational field in studying the motion of a triaxial satellite in a gravity field; and (2) also to expand theory for the uniaxial case to higher order.
Harmon, G. R.↗
Some Aspects of Attitude Stability of Tethered Space Stations
The stability of attitude motion of space stations composed by platforms connected tethers is studied. The motion is assumed to be three dimensional and the station rigid. First, the well known linearized theory is adopted and the location of different configurations in the stability chart is found; second, a destabilizing feature of finite amplitude motion is outlined as a function of inertia parameters.
Bergamasui, S.↗
Research and study in system optimization techniques progress report, 14 nov. 1964 - 14 feb. 1965
System optimization techniques - motion stability study on Liapunov function application to finding estimators and connection with differential equations
OPTIMIZATION↗
Motion cue effects on human pilot dynamics in manual control
Two experiments were conducted to study the motion cue effects on human pilots during tracking tasks. The moving-base simulator of National Aerospace Laboratory was employed as the motion cue device, and the attitude director indicator or the projected visual field was employed as the visual cue device. The chosen controlled elements were second-order unstable systems. It was confirmed that with the aid of motion cues the pilot workload was lessened and consequently the human controllability limits were enlarged. In order to clarify the mechanism of these effects, the describing functions of the human pilots were identified by making use of the spectral and the time domain analyses. The results of these analyses suggest that the sensory system of the motion cues can yield the differential informations of the signal effectively, which coincides with the existing knowledges in the physiological area.
Washizu, K.↗
Sloshing dynamics modulated angular momentum fluctuations actuated by gravity gradient acceleration associated with spacecraft slew motion
The mathematical formulation of orbital spacecraft sloshing dynamics for a partially filled cryogenic superfluid liquid helium II in a dewar container actuated by the gravity gradient acceleration associated with slew motion is studied. The Advanced X-Ray Astrophysics Facility-Spectroscopy (AXAF-S) spacecraft is chosen as a practical example in this study. Explicit mathematical expressions which manage orbital galaxy gradient acceleration with slew motion which is acting on the spacecraft fluid systems are derived. The numerical computation of sloshing dynamics is based on the non-inertia frame spacecraft bound coordinates and the solution of time-dependent, three-dimensional formulations of partial differential equations subject to initial and boundary conditions. This study discloses the capillary effect of sloshing dynamics governed liquid-vapor interface fluctuations, angular momentum and moment fluctuations of fluid system, and also buble mass center fluctuations driven by the gravity gradient acceleration associated with slew motion which affects the stability of the orbital spacecraft fluid system in a microgravity environment.
Hung, R. J.↗
Simulation study of the oscillatory longitudinal motion of an airplane at the stall
Hybrid simulation of the longitudinal motion of a straight-wing airplane at the stall was studied to investigate the effect of hysteresis in the development of lift and pitching moments on the wing as a function of angle of attack on the occurrence of longitudinal oscillations at the stall. Flight data for the simulated airplane and for various other airplanes are shown for the simulated airplane and for comparison. The results show that oscillations similar to those measured in flight may be obtained by incorporating hysteresis in the lift and pitching-moment curves.
Phillips, W. H.↗
The rotational motion of an earth orbiting gyroscope according to the Einstein theory of general relativity
The classical Poisson equations of rotational motion are used to study the attitude motions of an earth orbiting, rapidly spinning gyroscope perturbed by the effects of general relativity (Einstein theory). The center of mass of the gyroscope is assumed to move about a rotating oblate earth in an evolving elliptic orbit which includes all first-order oblateness effects produced by the earth. A method of averaging is used to obtain a transformation of variables, for the nonresonance case, which significantly simplifies the Poisson differential equations of motion of the gyroscope. Long-term solutions are obtained by an exact analytical integration of the simplified transformed equations. These solutions may be used to predict both the orientation of the gyroscope and the motion of its rotational angular momentum vector as viewed from its center of mass. The results are valid for all eccentricities and all inclinations not near the critical inclination.
Hoots, F. R.↗
Preliminary design of flight hardware for two-phase fluid research
This study defined the preliminary designs of flight software for the Space Shuttle Orbiter for three two-phase fluid research experiments: (1) liquid reorientation - to study the motion of liquid in tanks subjected to small accelerations; (2) pool boiling - to study low-gravity boiling from horizontal cylinders; and (3) flow boiling - to study low-gravity forced flow boiling heat transfer and flow phenomena in a heated horizontal tube. The study consisted of eight major tasks: reassessment of the existing experiment designs, assessment of the Spacelab facility approach, assessment of the individual carry-on approach, selection of the preferred approach, preliminary design of flight hardware, safety analysis, preparation of a development plan, estimates of detailed design, fabrication and ground testing costs. The most cost effective design approach for the experiments is individual carry-ons in the Orbiter middeck. The experiments were designed to fit into one or two middeck lockers. Development schedules for the detailed design, fabrication and ground testing ranged from 15 1/2 to 18 months. Minimum costs (in 1981 dollars) ranged from $463K for the liquid reorientation experiment to $998K for the pool boiling experiment.
Hustvedt, D. C.↗
The effects of visual deprivation on adaptation to a rotating environment
Visual deprivation effects on adaptation to rotating environment - Motion sickness studies
MOTION SICKNESS↗
Intelligent Systems Approach for Automated Identification of Individual Control Behavior of a Human Operator
Results have been obtained using conventional techniques to model the generic human operator?s control behavior, however little research has been done to identify an individual based on control behavior. The hypothesis investigated is that different operators exhibit different control behavior when performing a given control task. Two enhancements to existing human operator models, which allow personalization of the modeled control behavior, are presented. One enhancement accounts for the testing control signals, which are introduced by an operator for more accurate control of the system and/or to adjust the control strategy. This uses the Artificial Neural Network which can be fine-tuned to model the testing control. Another enhancement takes the form of an equiripple filter which conditions the control system power spectrum. A novel automated parameter identification technique was developed to facilitate the identification process of the parameters of the selected models. This utilizes a Genetic Algorithm based optimization engine called the Bit-Climbing Algorithm. Enhancements were validated using experimental data obtained from three different sources: the Manual Control Laboratory software experiments, Unmanned Aerial Vehicle simulation, and NASA Langley Research Center Visual Motion Simulator studies. This manuscript also addresses applying human operator models to evaluate the effectiveness of motion feedback when simulating actual pilot control behavior in a flight simulator.
Zaychik, Kirill B.↗
Motion sickness in the squirrel monkey
In this study of susceptibility to motion sickness the specific aims were to examine the effects of combined vertical rotation and horizontal acceleration, phenotype, sex, visual cues, morning and afternoon testing, and repeated test exposures on incidence, frequency, and latency of emetic responses. The highest emetic incidence of 89% with an emetic frequency of 2.0 during 60 min and a latency of 19 min from onset of testing occurred at 25 rpm and 0.5 Hz linear acceleration. Since the emetic responses were quite similar to man in eliciting motion stimuli it was concluded that the squirrel monkey represents a very suitable primate model for studies of motion and space sickness.
Ordy, J. M.↗