4,350 research outputs found
Measuring Gravito-magnetic Effects by Multi Ring-Laser Gyroscope
We propose an under-ground experiment to detect the general relativistic
effects due to the curvature of space-time around the Earth (de Sitter effect)
and to rotation of the planet (dragging of the inertial frames or
Lense-Thirring effect). It is based on the comparison between the IERS value of
the Earth rotation vector and corresponding measurements obtained by a
tri-axial laser detector of rotation. The proposed detector consists of six
large ring-lasers arranged along three orthogonal axes.
In about two years of data taking, the 1% sensitivity required for the
measurement of the Lense-Thirring drag can be reached with square rings of 6
side, assuming a shot noise limited sensitivity ().
The multi-gyros system, composed of rings whose planes are perpendicular to one
or the other of three orthogonal axes, can be built in several ways. Here, we
consider cubic and octahedron structures. The symmetries of the proposed
configurations provide mathematical relations that can be used to study the
stability of the scale factors, the relative orientations or the ring-laser
planes, very important to get rid of systematics in long-term measurements,
which are required in order to determine the relativistic effects.Comment: 24 pages, 26 Postscript figure
Measurement of the quadratic Zeeman shift of ^{85}Rb hyperfine sublevels using stimulated Raman transitions
We demonstrate a technique for directly measuring the quadratic Zeeman shift
using stimulated Raman transitions.The quadratic Zeeman shift has been measured
yielding [delta][nju] = 1296.8 +/-3.3 Hz/G^{2} for magnetically insensitive
sublevels (5S1/2, F = 2,mF = 0 -> 5S1/2, F = 3,mF = 0) of ^{85}Rb by
compensating the magnetic eld and cancelling the ac Stark shift. We also
measured the cancellation ratio of the differential ac Stark shift due to the
imbalanced Raman beams by using two pairs of Raman beams ([sigma]^{+},
[sigma]^{+}) and it is 1:3.67 when the one-photon detuning is 1.5 GHz in the
experiment
General relativistic Sagnac formula revised
The Sagnac effect is a time or phase shift observed between two beams of
light traveling in opposite directions in a rotating interferometer. We show
that the standard description of this effect within the framework of general
relativity misses the effect of deflection of light due to rotational inertial
forces. We derive the necessary modification and demonstrate it through a
detailed analysis of the square Sagnac interferometer rotating about its
symmetry axis in Minkowski space-time. The role of the time shift in a Sagnac
interferometer in the synchronization procedure of remote clocks as well as its
analogy with the Aharanov-Bohm effect are revised.Comment: 11 pages, 3 figure
Resolving the Degeneracy: Experimental tests of the New Self Creation Cosmology and a heterodox prediction for Gravity Probe B
The new theory of Self Creation Cosmology has been shown to yield a
concordant cosmological solution that does not require inflation, exotic
non-baryonic Dark matter or Dark Energy to fit observational constraints. In
vacuo there is a conformal equivalence between this theory and canonical
General Relativity and as a consequence an experimental degeneracy exists as
the two theories predict identical results in the standard tests. However,
there are three definitive experiments that are able to resolve this degeneracy
and distinguish between the two theories. Here these standard tests and
definitive experiments are described. One of the definitive predictions, that
of the geodetic precession of a gyroscope, has just been measured on the
Gravity Probe B satellite, which is at the present time of writing in the data
processing stage. This is the first opportunity to falsify Self Creation
Cosmology. The theory predicts a 'frame-dragging' result equal to GR but a
geodetic precession of only 2/3 the GR value. When applied to the Gravity Probe
B satellite, Self Creation Cosmology predicts an E-W
gravitomagnetic/frame-dragging precession, equal to that of GR, of 40.9
milliarcsec/yr but a -S gyroscope (geodetic + Thomas) precession of just 4.4096
arcsec/yr.Comment: LaTex, 15 pages. Correction of the prediction of the GP-B geodetic
measurement to 4.4096 arcsec/y
Photomechanical Investigation of Structural Behavior of Gyroscope Components. Task IV - Analysis of Initial Redesign of AB5-K8 GYROSCOPE
Photomechanics of structure and materials in redesigned AB5-K8 gyroscope component
Estimating Epipolar Geometry With The Use of a Camera Mounted Orientation Sensor
Context: Image processing and computer vision are rapidly becoming more and more commonplace, and the amount of information about a scene, such as 3D geometry, that can be obtained from an image, or multiple images of the scene is steadily increasing due to increasing resolutions and availability of imaging sensors, and an active research community. In parallel, advances in hardware design and manufacturing are allowing for devices such as gyroscopes, accelerometers and magnetometers and GPS receivers to be included alongside imaging devices at a consumer level.
Aims: This work aims to investigate the use of orientation sensors in the field of computer vision as sources of data to aid with image processing and the determination of a scene’s geometry, in particular, the epipolar geometry of a pair of images - and devises a hybrid methodology from two sets of previous works in order to exploit the information available from orientation sensors alongside data gathered from image processing techniques.
Method: A readily available consumer-level orientation sensor was used alongside a digital camera to capture images of a set of scenes and record the orientation of the camera. The fundamental matrix of these pairs of images was calculated using a variety of techniques - both incorporating data from the orientation sensor and excluding its use
Results: Some methodologies could not produce an acceptable result for the Fundamental Matrix on certain image pairs, however, a method described in the literature that used an orientation sensor always produced a result - however in cases where the hybrid or purely computer vision methods also produced a result - this was found to be the least accurate.
Conclusion: Results from this work show that the use of an orientation sensor to capture information alongside an imaging device can be used to improve both the accuracy and reliability of calculations of the scene’s geometry - however noise from the orientation sensor can limit this accuracy and further research would be needed to determine the magnitude of this problem and methods of mitigation
Modifications and Improvements to the Sea Beam System on Board R/V Thomas Washington
A number of modifications to the narrowbeam echo-sounder and echo processor of the Sea Beammultibeam bathymetric survey system have been implemented. These include the design and construction of a digital pitch compensator, the ability to use a variety of sensors for vertical reference, the design and construction of hardware test equipment, and an interface to the shipboard DEC VAX-11/730 computer for data logging, automation of start-up procedures, and performance monitorin
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