Showing papers on "Fiber published in 1981"

Signal transmission by optical solitons in monomode fiber

Abstract: A transmission rate of ≃1 Tbits/sec (≃0.1 Tbits/s) per 30 km can be achieved using envelope solitons with peak power of ≃10 W (≃10 mW) in a monomode optical fiber, respectively. Unlike the linear pulse in which the bit rate is limited by the group dispersion, the bit rate of soliton transmission is limited by the fiber loss and the input power. Conditions for achieving optimum transmission rate using solitons are theoretically obtained including the effects of fiber loss and second order group dispersion.

Role of Mahaim fibers in cardiac arrhythmias in man.

Abstract: Twelve patients with evidence of Mahaim fibers are reported, six with nodoventricular (NV) fibers and six with fasciculoventricular (FV) fibers. All patients with NV fibers had left bundle branch block morphology, and a sustained reentrant tachycardia with this morphology was proved in each case. In three of the six, ventriculoatrial dissociation occurred during tachycardia. We postulate that the mechanism of this tachycardia is a macroreentry circuit using the NV fiber for the antegrade limb and the His-Purkinje system with a portion of the atrioventricular node for the retrograde limb. ECGs of patients with FV fibers were varied, suggesting a functional relation to the right or left side of the septum. No direct relationship of FV fibers to observed arrhythmias could be found.

Fiber-reinforced concrete

Abstract: A fiber-reinforced concrete comprising a concrete matrix including two kinds of short fibers (A,B) one being a short fiber (A) having a Young's modulus higher than that of concrete, the other being a short fiber (B) which has a Young's modulus lower than that of concrete a showing good adhesiveness to concrete. The said fibers are mixed in a predetermined ratio and are dispersed in the concrete matrix. A reinforcing material for concrete is also dislcosed, such material consisting of a mixture of the fibers (A.B) as mentioned above.

Temporal self-imaging effect in single-mode fibers

Abstract: The transfer of information in fibers with a large dispersion of the first order is accomplished by a temporal analog of the self-imaging effect. The simulation of signal propagation in a single-mode fiber is considered by using the analogous Fresnel diffraction experiment.

Closed-loop, low-noise fiber-optic rotation sensor.

Abstract: A closed-loop, multiturn fiber-optic rotation sensor has been developed that exhibits low noise of the order of 0.1°/h for an averaging time of 30 sec. This performance is consistent with the photon-noise limit for our setup. The length of the fiber is 200 m, and the coil diameter is 19 cm. Nonreciprocal phase modulation is accomplished with an electro-optic crystal driven at 470 kHz, and closed-loop operation is achieved by means of acousto-optic frequency shifters.

On the relationship between engineering properties and delamination of composite materials

Abstract: The influence of the coefficient of mutal influence, Poisson's ratio and coefficients of thermal and moisture expansion on delamination is studied. Engineering theories are compared to finite element and experimental results. It is shown that the mismatch in coefficients of mutual influence can have a strong influence on delamination with fiber angles in the 10-15 degree range being critical for adjacent layer combinations. The mismatch in coefficient of mutual influence is reduced by a factor of two and the interlaminar shear stress is reduced significantly when the + or - adjacent layers are interspersed between 0 and 90 degree layers. It is shown how the results can be used for design of composite laminates.

Fiber resonator gyroscope: sensitivity and thermal nonreciprocity.

Abstract: The rotational sensitivity of the fiber resonator gyro is derived and shown to be approximately equal to that of the fiber interferometer gyro for typical fiber and source parameters. The fiber resonator, like the fiber interferometer, is susceptible to errors due to thermally induced nonreciprocity; however, by reducing splice and coupler losses, it should be possible to reduce these errors well below those in the fiber interferometer.

Photoluminescence in as-drawn and irradiated silica optical fibers: an assessment of the role of non-bridging oxygen defect centers

Abstract: The spectral and temporal characteristics of the photoluminescence in as-drawn and irradiated silica and doped silica fiber-optic waveguides have been investigated. The extended pathlength available with a fiber-optic geometry has offered the opportunity to make high sensitivity emission measurements on high silica glasses under both steady state and pulsed laser excitation. The analyses of the fiber data coupled with emission studies on selectivity doped bulk glasses suggest that the dominant emission band centered near 650 nm is intrinsic to defects in the SiO network, specifically, dangling non-bridging oxygens ions which can be generated by irradiation, fiber drawing or by the introduction of network modifying ions such as alkali.

Fiber rearrangements during the molding of continuous fiber composites. I. Flat cloth to a hemisphere

Abstract: The goal of this series of reports is to develop rapid computational procedures for determining the rearrangement of fibers that occurs during the molding of continuous fiber composite components for flat layups. This report considers the shaping of a cloth into a hemisphere. /the numerical procedure developed predicts that a cloth can be shaped into a hemisphere without wrinkling. This prediction is compared with experiment, and various paramenters connected with the shaping calculation are discussed.

Surfaced oriented strand board

Abstract: Wood particles are distributed in selected patterns and bonded together by an adhesive to form a multilayer wood particleboard. The board has a central core of three layers of wood strands sandwiched between two outer surface-forming layers of fine wood particles. The wood strands forming the central core have a length which is several times greater than their width, with their fiber elements substantially parallel to their length. The fine wood particles are irregularly contoured wood particles having a width and thickness less than the average width of the strands forming the central core layers. Each of the three central core layers has its wood strands distributed in a parallel orientation pattern, with the strands in the outer two layers of the core parallel and the strands of the center layer perpendicular to those of the outer two layers to form a layer-to-layer cross-oriented strand pattern. Both surface-forming layers are composed of fine wood particles of various sizes distributed in an unoriented graduated size pattern from the outer surface to the central core, with the progressively smaller or finer wood particles closer to the outer surface of the surface layers. The multilayer wood particleboard is made by forming a multilayer mat of adhesive coated wood particles, with each layer having the wood particle and pattern characteristics described above, and then compressing the adhesive coated wood particles forming the multilayer mat in a hot platen press.

Nonwoven fabrics and method of producing the same

Abstract: A nonwoven fabrics comprising an upper layer having a substantially smooth surface and a lower layer having a density lower than that of the upper layer is provided; wherein the upper layer contains, as a principal element thereof, hydrophobic fibers, denier thereof being finer than in the lower layer, and containing a larger amount of adhesive bonding materials than in the lower layer; the lower layer contains, as a constituent fiber thereof, hydrophilic fibers and hydrophobic fibers, denier thereof being coarser than in the upper layer, and containing a smaller amount of adhesive bonding materials than in the upper layer.

Interplay of design parameters and fabrication conditions on the performance of monomode fibers made by MCVD

Abstract: An apparently undocumented loss mechanism in monomode fibers with germanium doped cores is demonstrated. This loss increases as the fiber drawing temperature and/or the germanium concentration increases. By consideration of this mechanism in the fiber design and fabrication, losses lower than previously reported have been achieved both in fiber with low germanium concentration (0.38 dB/km at 1.3 μm) and in higher doped, dispersion shifted fiber (0.37 dB/km at 1.55μm). The constraints on fiber design as a consequence of this loss mechanism are discussed.

Low-calorie foods

Abstract: Low-caloric food products are formulated with a high level (in excess of 10% by dry weight) of polysaccharide and/or polyol components and with a level of dietary fiber compositions equal to from 1/4 to 2 times the combined level of polysaccharides and polyols contained in the product and effective to reduce polysaccharide and/or polyol-induced diarrhea. Preferred dietary fiber compositions are soy fiber concentrate and citrus albedo.

Pyrolyzed pitch coatings for carbon fiber

Abstract: Carbon fibers in a carbon-fiber-reinforced metal-matrix composite having a relatively very high modulus are treated with a relatively thin amorphous carbon coating precedent to a metal-oxide film to improve the adhesion thereof to the carbon fiber thereby facilitating the wetting of carbon fibers to molten matrix metal.

Fiber-reinforced cement and process

Abstract: A hydraulic cement mortar comprising uniformly dispersed reinforcing fibrillated plastic filaments having microfibrillated structure and elements manufactured therefrom have improved mechanical isotropic properties, such as enhanced performance regarding their semi-elastic limit and impact loading characteristics. It is disclosed also the process for manufacturing said elements.

Coefficient of thermal expansion for composites with randomly oriented fibers

Abstract: The effective coefficient of thermal expansion is derived for fiber com posites in two dimensional quasi-isotropic form and three-dimensional isotropic form. These systems represent constructions that have fibers ran domly oriented in a plane and in three dimensions. The effective coeffi cients of thermal expansion are related to the thermal-mechanical proper ties of individual fiber and matrix phases. These results are put into asymp totic forms appropriate to very stiff fiber systems. The asymptotic predic tions are evaluated against the complete forms, and both results are com pared with an experimental result.

Solution structural studies of chromatin fibers.

Abstract: We report solution structural studies on 9--16-kilobase (kb) fragments of the 30-nm chromatin fiber isolated from calf thymus nuclei. Samples were stabilized by dimethylsuberimidate cross-linking in 100 mM salt concentration to ensure retention of a compact conformation. Electron microscopy, sedimentation diffusion, light scattering, and gel electrophoresis were used to characterize materials which were fractionated by size by utilizing sucrose gradient sedimentation. Measurements reported include the translational frictional coefficient as determined by quasielastic light scattering and the rotational frictional coefficient as deduced from transient electric dichroism. These frictional properties were combined to yield 33 +/- 3 nm for the diameter of the fiber and a length of 1.5 +/- 0.1 nm per nucleosome. Assuming a superhelix pitch of 11 nm, we calculate 7.5 +/- 0.5 nucleosomes per superhelical turn. The 30-nm fiber was found to reach saturation of electric field orientation at about 10--13 kV/cm and to lack a detectable permanent dipole moment, implying no polarity of the fiber. The limiting reduced dichroism rho was found to be +0.06, intermediate between the values expected if the nucleosomal disk diameters were parallel (rho expected = -3/8) or perpendicular (rho expected +3/4) to the fiber axis. This result implies an average angle of 51 degrees between the fiber axis and the local DNA (nucleosomal) superhelix axis and rules out many of the simple models which have been proposed for the detailed structure of the 30-nm fiber.