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Commercial O-rings made from 13 different rubber compounds were tested for physical properties after 7 and 12 years of shelf aging. No gross changes were observed in tensile strength, elongation, or compression deflection characteristics.
The analysis of the measured ion fluxes during the several day storm recovery period and the assumption that beside hydrogen other ions were present and that the decays were exponential in nature, it was possible to establish three separate lifetimes for the ions. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H(+), O(+), and He(+) in the energy and L-value range of the data. This inference technique, thus, establishes the presence of measurable and appreciable quantities of oxygen and helium ions as well as protons in the storm-time ring current. Indications that He(+) may also be present under these same conditions were found.
Measurements of the Fresnel-Fizeau effect in a fiber ring interferometer gyroscope are reported. The presence of the dispersion term in the Fresnel drag coefficient was discernable. The temperature dependence of the coefficient bears on the temperature sensitivity of the optical fiber gyroscope. An alternate approach to measuring fiber dispersion is an added benefit, leading to determination of maximum pulse rate transmitted through single-mode fibers.
Displacement results of plane boundary collocation analysis are given for various locations on the inner boundaries of radially cracked ring segments (C-shaped specimens) subject to two complementary types of loading. Results are presented for ratios of outer to inner radius in the range of 1.1 to 2.5 and ratios a/W in the range 0.1 to 0.8, where a is the crack length for a specimen of wall thickness W. By combination of these results the resultant displacement coefficient or the corresponding influence coefficient can be obtained for any practical load line location of a pin-loaded specimen.
Report presents perameterpreturbation test program (using nineteen combinations of Test perameters) for elastomeric O-rings conducting for range of materials, temperatures, amplitudes, squeeze valves, stretch valves, cross-sectional diameters, and groove widths. Tests data were plotted and Power law lines fitted to sets of data.
Triazine compounds and cross-linked polymer compositions are made by heating aromatic nitriles to a temperature in the range of from about 100 C to about 700 C, and preferably in the range of from about 200 C to about 350 C, in the presence of a catalyst or mixture of catalysts selected from one or more of the following groups: (1) organic sulfonic and sulfinic acids, (2) organic phosphonic and phosphinic acids, and (3)metallic acetylacetonates, at a pressure in the range of from about atmospheric pressure to about 10,000 psi and preferably in the range of from about 200 psi to about 750 psi. Aromatic nitrile-modified (terminated and/or appended) imide, benzimidazole, imidazopyrrolone, quinoxaline, and other condensation type prepolymers or their precopolymers are made which are trimerized with or without a filler by the aforementioned catalytic trimerization process into triaryl-s-triazine ring containing or cross-linked polymeric or copolymeric products useful in applications requiring high thermal-oxidative stability and high performance structural properties at elevated temperatures.
The study investigates the mechanics of ring formation in lunar basins by collapse or slumping. Two classes of models are presented in order to broaden the range of plausible mechanisms involved. Extrusion flow models which assume a weak layer underlying a strong layer as well as plastic flow models which assume a continuous decrease of cohesion strength with depth are considered. In both classes, strength or resistance to deformation decreases with depth. If this decrease is rapid enough, in either set of models, at least one concentric fault scarp forms. The ratio between the scarp radius and the crater radius varies between 1.2 and about 2.7 depending on the model, and is thus in the range of observed radius ratios.
Fluctuations of the pressure field in the vicinity of a jet are simulated numerically by a flow model consisting of axially symmetric vortex rings with viscous cores submerged in a uniform stream. The time interval between the shedding of successive vortices is taken to be a random variable with a probability distribution chosen to match that from experiments. It is found that up to 5 diameters downstream of the jet exit, statistics of the computed pressure field are in good agreement with experimental results. Statistical comparisons are provided for the overall sound pressure level, the peak amplitude, and the Strouhal number based on the peak frequency of the pressure signals.
Aperture synthesis maps of Saturn and its ring system are presented. The maps are free from most of the assumptions about the brightness structure of Saturn that were used in a previous model-fitting analysis. Generally, the maps confirm the model-fitting results, with the exception that the brightness temperature of the planet determined by the models is greater than it needs to be in order to match the contours in the map. This discrepancy is attributed to random errors in the phase of the visibility function.
In ball and socket joint where electrical insulator such as polytetrafluoroethylene is used as line to minimize friction, good electrical contact across joint may be needed for lightning protection or to prevent static-charge build-up. Electrical contact is maintained by ring of spring-loaded fingers mounted in socket. It may be useful in industry for cranes, trailers, and other applications requiring ball and socket joint.
The explicit expressions for an elastic-plastic trapezoidal ring element are presented and implemented in NASTRAN computer program. The material is assumed to obey the von Mises' yield criterion, isotropic hardening rule and the Prandtl-Reuss flow relations. For the purpose of demonstration, two elastic-plastic problems are solved and compared with previous results. The first is a plane-strain tube under uniform internal pressure and the second, a finite-length tube loaded over part of its inner surface. A very good agreement was found in both test problems.
The CIVM-JET 4C computer program for the 'finite strain' analysis of 2 d transient structural responses of complete or partial rings and beams subjected to fragment impact stored on tape as a series of individual files. Which subroutines are found in these files are described in detail. All references to the CIVM-JET 4C program are made assuming that the user has a copy of NASA CR-134907 (ASRL TR 154-9) which serves as a user's guide to (1) the CIVM-JET 4B computer code and (2) the CIVM-JET 4C computer code 'with the use of the modified input instructions' attached hereto.
In the present paper, long-period and secular variations of the longitude of ascending node are derived for a particle orbiting an oblate precessing planet subjected to perturbation by an exterior satellite moving along a low-inclination orbit. It is shown that precession of Saturn under the solar torque, which causes the Laplace plane to be noninertial, is also effective in producing a forced inclination. The height above the Laplace plane associated with this variation is several meters for a particle located in the middle of the ring.
By the method of electron reflection, we have identified seven well-defined magnetized regions in the equatorial belt of the lunar far side sampled by the Apollo 16 Particles and Fields subsatellite. Most of these surface magnetic fields lie within one basin radius from the rim of a ringed impact basin, where thick deposits of basin ejecta are observed or inferred. The strongest of the seven magnetic features is linear, at least 250 km long, and radial to the Freundlich-Sharonov basin. The apparent correlation with basin ejecta suggests some form of impact origin for the observed permanently magnetized regions.
An unusual SAR arc observed during the growth phase of the ring current is described. Proton precipitation was observed, with electron temperature enhancements throughout the region, and an F-region trough present at the equatorward boundary; a high flux of low energy at the SAR arc location and a 'slot' in the ambient electron density are characteristic of this event. Comparisons are made with S3-A spacecraft observations made in the equatorial region at the same time and with Isis-II observations of a more normal SAR arc; the kinetic Alfven process described by Hasegawa and Mima (1978) appears to account for the acceleration of these low energy electrons, although an auroral-type acceleration process cannot be excluded.
The paper considers a proposed source for the geomagnetic storm main phase ring current. It is shown that the flux increases of trapped ions and electrons observed by Explorer 45 at L below 4 during two large geomagnetic storms can be explained by inward radial displacement of the preexisting trapped particle distribution. The proposed source requires only the acceleration of the previously entrapped particle population by inward displacement under conservation of the first two adiabatic invariants. It is suggested that a significant difference between large geomagnetic storms and typical substorm activity may be the inward convection occurring over a large longitude range during storms, but only over a small longitude range during typical substorms.
A method for individual registration of protons, and helium and oxygen ions, with energies E for a charge on the order of 100 kev/q in the ring currents of the Earth's magnetosphere was examined. The method is based on the various specific losses in energy by these ions in matter. The ion current, selected according to E/q, is passed through a solid target, after which identification of the masses is carried out, based on the energy losses in the possibly to reliably divide the flows of protons, and helium and oxygen ions.
The suggestion of O'Keefe (1980) that the terminal Eocene event was caused by rings of tektite material encircling the earth is discussed. It is argued that the assumption that the tektites are of lunar volcanic origin is unwarranted and contrary to existing data, including the lack of lunar rocks of suitable composition, the lack of lunar rocks of the correct age, the lack of evidence that the North American tektites fell throughout a sedimentary rock column of a few million years, and the nondetection of a tektite with a measurable cosmic ray exposure age. Alternatively, it is suggested that the terminal Eocene event may be associated with volcanic ash, air-fall tuff and bentonite in the late Eocene. O'Keefe replies that the hypothesis of the terrestrial origin of the tektites conflicts with the laws of physics, for example in the glass structure and shaping of the tektites. Furthermore, evidence is cited for lunar rocks of the proper major-element composition and ages, and it is noted that the proposed solar Poynting-Robertson effect would account for the particle fall distributions and cosmic ray ages.