875 research outputs found
A heuristic mathematical model for the dynamics of sensory conflict and motion sickness
By consideration of the information processing task faced by the central nervous system in estimating body spatial orientation and in controlling active body movement using an internal model referenced control strategy, a mathematical model for sensory conflict generation is developed. The model postulates a major dynamic functional role for sensory conflict signals in movement control, as well as in sensory-motor adaptation. It accounts for the role of active movement in creating motion sickness symptoms in some experimental circumstance, and in alleviating them in others. The relationship between motion sickness produced by sensory rearrangement and that resulting from external motion disturbances is explicitly defined. A nonlinear conflict averaging model is proposed which describes dynamic aspects of experimentally observed subjective discomfort sensation, and suggests resulting behaviours. The model admits several possibilities for adaptive mechanisms which do not involve internal model updating. Further systematic efforts to experimentally refine and validate the model are indicated
A heuristic mathematical model for the dynamics of sensory conflict and motion sickness
The etiology of motion sickness is now usually explained in terms of a qualitatively formulated sensory conflict hypothesis. By consideration of the information processing task faced by the central nervous system in estimating body spatial orientation and in controlling active body movement using an internal model referenced control strategy, a mathematical model for sensory conflict generation is developed. The model postulates a major dynamic functional role for sensory conflict signals in movement control, as well as in sensory motor adaptation. It accounts for the role of active movement in creating motion sickness symptoms in some experimental circumstances, and in alleviating them in others. The relationship between motion sickness produced by sensory rearrangement and that resulting from external motion disturbances is explicitly defined. A nonlinear conflict averaging model describes dynamic aspects of experimentally observed subjective discomfort sensation, and suggests resulting behavior
Habituation to novel visual vestibular environments with special reference to space flight
The etiology of space motion sickness and the underlying physiological mechanisms associated with spatial orientation in a space environment were investigated. Human psychophysical experiments were used as the basis for the research concerning the interaction of visual and vestibular cues in the development of motion sickness. Particular emphasis is placed on the conflict theory in terms of explaining these interactions. Research on the plasticity of the vestibulo-ocular reflex is discussed
Research on gas-surface interactions, 1966-1967. Part 1 - Project summary final report, 11 Aug. 1966 - 11 Oct. 1967
High intensity shock tube driven molecular beam for gas-surface interaction
Computer program to assess impact of fatigue and fracture criteria on weight and cost of transport aircraft
A preliminary design analysis tool for rapidly performing trade-off studies involving fatigue, fracture, static strength, weight, and cost is presented. Analysis subprograms were developed for fatigue life, crack growth life, and residual strength; and linked to a structural synthesis module which in turn was integrated into a computer program. The part definition module of a cost and weight analysis program was expanded to be compatible with the upgraded structural synthesis capability. The resultant vehicle design and evaluation program is named VDEP-2. It is an accurate and useful tool for estimating purposes at the preliminary design stage of airframe development. A sample case along with an explanation of program applications and input preparation is presented
Research on integration of visual and motion cues for flight simulation and ride quality investigation
Vestibular perception and integration of several sensory inputs in simulation were studied. The relationship between tilt sensation induced by moving fields and those produced by actual body tilt is discussed. Linearvection studies were included and the application of the vestibular model for perception of orientation based on motion cues is presented. Other areas of examination includes visual cues in approach to landing, and a comparison of linear and nonlinear wash out filters using a model of the human vestibular system is given
A heuristic mathematical model for the dynamics of sensory conflict and motion sickness
The etiology of motion sickness is explained in terms of a qualitatively formulated sensory conflict hypothesis. By consideration of the information processing task faced by the central nervous system in estimating body spatial orientation and in controlling active body movement using an internal model referenced control strategy, a mathematical model for sensory conflict generation is developed. The model postulates a major dynamic functional role for sensory conflict signals in movement control, as well as in sensory-motor adaptation. It accounts for the role of active movement in creating motion sickness symptoms in some experimental circumstances, and in alleviating them in others. The relationship between motion sickness produced by sensory rearrangement and that resulting from external motion disturbances is explicitly defined. A nonlinear conflict averaging model is proposed which describes dynamic aspects of experimentally observed subjective discomfort sensation, and suggests resulting behaviors
The origin of galaxy scaling laws in LCDM
It has long been recognized that tight relations link the mass, size, and
characteristic velocity of galaxies. These scaling laws reflect the way in
which baryons populate, cool, and settle at the center of their host dark
matter halos; the angular momentum they retain in the assembly process; as well
as the radial distribution and mass scalings of the dark matter halos. There
has been steady progress in our understanding of these processes in recent
years, mainly as sophisticated N-body and hydrodynamical simulation techniques
have enabled the numerical realization of galaxy models of ever increasing
complexity, realism, and appeal. These simulations have now clarified the
origin of these galaxy scaling laws in a universe dominated by cold dark
matter: these relations arise from the tight (but highly non-linear) relations
between (i) galaxy mass and halo mass, (ii) galaxy size and halo characteristic
radius; and (iii) from the self-similar mass nature of cold dark matter halo
mass profiles. The excellent agreement between simulated and observed galaxy
scaling laws is a resounding success for the LCDM cosmogony on the highly
non-linear scales of individual galaxies.Comment: Contribution to the Proceedings of the Simons Conference
"Illuminating Dark Matter", held in Kruen, Germany, in May 2018, eds. R.
Essig, K. Zurek, J. Fen
Investigation into the mechanism of degradation of solar cells with silver- titanium contacts Final report
Electrochemical tests and physical measurements to determine degradation mechanism in solar cells with silver-titanium contacts exposed to humid atmosphere
Glimmerglass Volume 03 Number 19 (1944)
Official Student Newspaper
Issue is 4 pages long
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