Time and Physical Geometry

1967 ◽  
Vol 64 (8) ◽  
pp. 240-247 ◽  
Author(s):  
Hilary Putnam ◽  
Keyword(s):  
Physical Geometry

A SUBSURFACE ELECTROMAGNETIC PULSE RADAR

Geophysics ◽  
1976 ◽  
Vol 41 (3) ◽  
pp. 506-518 ◽  
Author(s):  
David L. Moffatt ◽  
R. J. Puskar
Keyword(s):  
Electromagnetic Pulse ◽  
Soft Rock ◽  
Rock Surface ◽  
Subsurface Geology ◽  
Pulse Radar ◽  
Horizontal Stratification ◽  
Physical Geometry ◽  
Time Record ◽  
Orthogonal Orientation ◽  
A Minor

An electromagnetic pulse radar has been developed for investigation of subsurface geology and man‐made targets. The radar uses separate broadband dipole‐type antennas for transmission and reception. The antennas are well matched to the soil or rock surface. An orthogonal orientation of the antennas on the medium surface effectively decouples them and also prevents reflections from the air‐medium interface or any horizontal stratification from being seen. Two versions of the radar are used: small 6-ft dipoles with a shock‐type (250 picosec) pulse for shallow soundings and 24-ft dipoles with a 45 nanosec pulse for deeper soundings. Signatures of faults, joints, cavities, and lithologic contrasts in soft rock have been obtained with the radar, and these results are presented. A sampling oscilloscope acts as a receiver for the radar, and the target signatures are isolated portions of the time record whose time delays agree with the physical geometry and measured pulse velocities for the medium. For a large void at a depth of 20 ft in limestone, a frequency domain signature is also given to illustrate the potential of using both temporal and spectral signatures. Signatures of an exposed fault in a dolomite quarry are used via mapping measurements to delineate the direction of a minor fault. Signatures of two lithologic contrasts at depths of 40 ft in the dolomite are given. The signatures of a drift coal mine tunnel as measured from a hill 11 to 26 ft above the tunnel are shown. Unique features of the radar are enumerated and present capabilities are summarized.

The Deresination of Guayule: A Physical Model. Part II: A Two-Component Analog for Deresination

1984 ◽  
Vol 57 (2) ◽  
pp. 370-378
Author(s):  
S. Budiman ◽  
D. McIntyre
Keyword(s):  
Diffusion Coefficients ◽  
Abietic Acid ◽  
Additive Model ◽  
Molecular Size ◽  
Design Parameters ◽  
Model Compounds ◽  
Diffusion Behavior ◽  
Diffusion Studies ◽  
Two Component ◽  
Physical Geometry

Abstract Based on GPC, the worm resin can be separated into two distinct groups, large and small. To obtain the overall diffusion coefficients for the two groups that could be useful as commercial design parameters, the worms were converted into wet worm crepe. Diffusion studies with model compounds, abietic acid, and trilinolein, reveal that: (a) their diffusion coefficients for desorption into acetone are inversely proportional to their respective molecular size, (b) the diffusion behavior of the two model compounds in a mixture can be fitted to a simple additive model, and (c) their diffusion coefficients are quite similar to those of the two groups of resin constituents (large and small). It is, therefore, possible to model and optimize a commercial deresination process for guayule worms on the basis of the diffusion behavior of two model compounds linolein and abietic acid and the physical geometry.

Entwicklung einer physikalischen Geometrie der Raum-Zeit zum Zwecke der Interpretation der allgemeinen Relativitätstheorie

1964 ◽  
Vol 19 (6) ◽  
pp. 665-675 ◽  
Author(s):  
Ernst Schmutzer
Keyword(s):  
General Relativity ◽  
Physical Meaning ◽  
Physical Space ◽  
Equation Of Motion ◽  
Gravitational Acceleration ◽  
3 Dimensional ◽  
Einstein's Equation ◽  
Physical Geometry ◽  
Fixed System ◽  
Physical Components

Up to date the interpretation of the theory of general relativity is discussed. One cause for this situation is the use of mathematical coordinates without physical meaning. In continuation of thoughts of MØLLER and CATTANEO here physical coordinates are used and on this basis a 4-dimensional physical geometry of space-time is developed by projection the mathematical tensor components into physical components. For studying the curvature of the 3-dimensional physical space and for other purposes new socalled projective partial and projective covariant derivations are introduced. On this foundation EINSTEIN’S equation of motion is investigated. Definitions for the CORIOLIS acceleration and the centrifugal-gravitational acceleration for a fixed system of reference are given. The problem of energy conservation is analysed.

A Computational Model for the Stereoscopic Optics of a Head-Mounted Display

1992 ◽  
Vol 1 (1) ◽  
pp. 45-62 ◽  
Author(s):  
Warren Robinett ◽  
Jannick P. Rolland
Keyword(s):  
Virtual Reality ◽  
Computational Model ◽  
Relative Position ◽  
Three Dimensional ◽  
Model Parameters ◽  
Head Mounted Display ◽  
Interpupillary Distance ◽  
Modeling Errors ◽  
Physical Geometry ◽  
Physical Objects

For stereoscopic photography or telepresence, orthostereoscopy occurs when the perceived size, shape, and relative position of objects in the three-dimensional scene being viewed match those of the physical objects in front of the camera. In virtual reality, the simulated scene has no physical counterpart, so orthostereoscopy must be defined in this case as constancy, as the head moves around, of the perceived size, shape, and relative positions of the simulated objects. Achieving this constancy requires that the computational model used to generate the graphics matches the physical geometry of the head-mounted display being used. This geometry includes the optics used to image the displays and the placement of the displays with respect to the eyes. The model may fail to match the geometry because model parameters are difficult to measure accurately, or because the model itself is in error. Two common modeling errors are ignoring the distortion caused by the optics and ignoring the variation in interpupillary distance across different users. A computational model for the geometry of a head-mounted display is presented, and the parameters of this model for the VPL EyePhone are calculated.

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