Change In Scale Factor Research Articles

The Effects of Image Scale Factor on Vestibulo-Ocular Reflex Adaptation and Simulator Sickness in Head-Coupled Virtual Environments

An experiment was conducted to determine the effects of virtual image scale factor on vestibulo-ocular reflex (VOR) adaptation and simulator sickness as a result of exposure to a head-coupled virtual interface. Subjects were exposed for 30 minutes, completing visual search tasks using active, unrestricted yaw head movement rotations. Three levels of image scale-factor changes (0.5X, 1.0X, 2.0X magnification) were explored. It was hypothesized that scale factors deviating from 1.0X magnification would cause VOR gain adaptation and increased simulator sickness. A secondary hypothesis predicted a moderate correlation between VOR gain adaptation and simulator sickness. Results demonstrated that significant VOR adaptation occurred only in the 0.5X and 2.0X scale conditions. VOR gain decreased an average of 15% in the 0.5X condition and increased an average of 6% in the 2.0X condition. Simulator sickness magnitudes in these two conditions were over twice that of the 1.0X condition. Only weak correlations were found between VOR gain adaptation and simulator sickness. Virtual interface design guidelines are suggested to minimize unwanted interface-generated effects on the user.

Secular gravity variations: Recent crustal movements or scale factor changes?

For the observation of secular variations of the Earth's gravity field today mainly relative spring gravimeters are used. The scale factors of relative gravimeters may change in time. Scale factor changes generate large virtual gravity changes, if they are neglected. Therefore the control of scale factor changes is necessary in secular gravity research. We can determine absolute and relative scale factors of gravimeters with an accuracy of ⩾±5 ∗ 10 −5 . On data from a gravity network established along the North Anatolian fault (Turkey) the effect of scale factor control is investigated. Improved scale factor control of gravimeters delivers more reliable secular gravity changes, which are consistent with ideas about the rate of vertical crustal movements in this tectonic active area.

Dispersion-induced nonreciprocal effects in phase-nulling fibre gyroscopes

The nonreciprocal phase error introduced in phase-nulling gyroscopes by fibre dispersion is evaluated for a range of operating wavelengths and temperatures. It is found that small amounts of nonlinearity, scale factor change and zero bias arise, which all drift with temperature. However, if two frequency modulators are used to give zero-order fringe operation, dispersion-induced nonreciprocities have almost negligible effect on gyro performance.

The influence of profile analysis on structural parameters and deformation density distributions

Nett X-ray diffraction intensities have been determined from measured step-scan profiles of deuterated 2,5- dimethyl-3-hexyne-2,5-diol by four different profile analysis procedures. Least-squares refinements based on the different sets of F values showed that variations in profile analysis method may change the coordinates by 1.5 times the σ of 0.8 x 10-4 Å and the thermal parameters by twice the σ of 1.4 x 10-5 Å2. The change in scale factor is 1.2% or 4σ. A correct choice of refinement procedure, in which full-angle data are used for the determination of the scale, turned out to be more important for the calculation of reliable deformation densities than the choice of profile-analysis method.

Effects of Magnification and Observation Time on Target Identification in Simulated Orbital Reconnaissance

When deciding what telescopic power is required to find objects of interest on the ground while flying over the earth at relatively high speeds, the positive value of an increased magnification must be balanced against the negative effects of a decreased observation time and an increased movement rate. The relative trade-off between these two factors—magnification and time—was compared in a series of three studies in which photographic imagery was used to simulate a telescopic view of the earth from a spacecraft orbiting at 175 nautical miles. Target acquisition decreased as image scale factor decreased and as image movement rate increased. When a change in scale factor was inversely proportional to a change in observation time, the positive effects of an increased image scale factor tended to exceed the negative effects of a decreased observation time and increased image movement rate within the limits of this study. The theoretical and practical implications of these and other results are discussed.

A Dynamical Determination of the Astronomical Unit by a Least-Squares Fit to the Orbit of Pioneer V.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Dynamical Determination of the Astronomical Unit by a Least-Squares Fit to the Orbit of Pioneer V. McGuire, J. B. ; Morrison, D. D. ; Wong, L. Abstract Squares Fit to the Orbit of Pioneer V. J. B. McG~i~~, D. D. MORRISON, AND L.WONG, Space Technology Laboratories, Inc., Los Angeles, California (introduced by GUIDO M~~~c~). -The astronomical unit has long eluded precise determination because it enters the two-body Kepler problem as a scale factor, and as a scale factor changes in the size of the astronomical unit do not change any angular measurement. Since angles are the primary measured quantitites of classical astronomy, the astronomical unit does not enter the dynamics and thus the astronomical unit has been determined by geometrical means (i.e., measuring solar parallax). If, however, one is concerned with a three-body problem, the effect of a change in the astronomical unit is to add a secular (i.e., time-increasing) perturbation to the motion. This effect has been utilized by E. K. Rabe (1950, Astron. J. 54, 112) in the so- called dynamical method of astronomical unit determination. It was first suggested by R. C. Booton (1960, Space Technology Laboratories Tech. Rept. 60-0000- 00215) that the orbit of an interplanetary probe could be affected (since it is a three-body problem) by a change in the astronomical unit, and thus the astronomical unit should be measurable by a least- squares fit to the radio Doppler data from such a probe. Previous determinations of the astronomical unit have been made by both dynamical and geometrical means. The most recent of the dynamical measurements is that of Rabe, which has a quoted accuracy of *4~4 parts in 10~. The most recent geometrical measurement is that of Spencer-Jones (1941, Mcm. Roy. Astron. Soc. LXVI, Part II) which has a quoted accuracy of *1.1 parts in 10~. The measured values of the astronomical unit, however, differ by one part in 10~. At the time of writing of this abstract the tracking of the Pioneer V probe is incomplete; thus the accuracy of the measurement of the astronomical unit is as yet unknown. Unfortunately, radio contact with Pioneer V will not be maintained to a sufficient distance from the earth to effect any improvement in the uncertainties in the astronomical unit quoted by Rabe. It is hoped, however, that sufficient accuracy will be attained to lend more weight to either Rabe or the Spencer-Jones value of the astronomical unit. It will be shown that Doppler tracking of an interplanetary probe to a distance of 80000000 miles from the earth could yield a value of the astronomical unit which is competitive in accuracy with Rabe's determination. Supported by National Aeronautics and Space Administration. Publication: The Astronomical Journal Pub Date: 1960 DOI: 10.1086/108136 Bibcode: 1960AJ.....65R.493M full text sources ADS |

Global Navigation Display

this paper deals with the development of a display technique utilizing a point source lamp for projection through an optical quality globe to create a continuous cartographical display. The globe contains cartographic information on a one to two million scale. The display is capable of scale factor changes without loss of detail or the use of optical systems to retain the focus. The globe is gimballed on four axes to provide the capability of either command or slave operation of the display when it is used in conjunction with an automatic navigational computer. Servo accuracies which are capable of maintaining positional display within one tenth of a minute of latitude and longitude are used for the various drive loops. Slave operation is also maintained for either heading or track reference and thereby permits the orientation of the display to be maintained under all operating conditions.