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Showing papers on "Fiber published in 1972"


Journal ArticleDOI
Smith Rg1
TL;DR: These effects of stimulated Raman and Brillouin scattering must be considered in the design of optical communication systems using low loss fibers especially when low loss optical fibers are used.
Abstract: The effect of stimulated Raman and Brillouin scattering on the power handling capacity of optical fibers is considered and found to be important especially when low loss optical fibers are used. A critical power below which stimulated effects may be neglected is defined for forward and backward Raman scattering and for backward Brillouin scattering. This critical power is determined by the effective core area A, the small signal attenuation constant of the fiber alpha, and the gain coefficient for the stimulated scattering process (gamma0), by the approximate relation P(crit) approximately 20Aalpha/(gamma0). For a fiber with 20-dB/km attenuation and an area of 10(-7) cm(2)P(crit) approximately 35 mW for stimulated Brillouin scattering. For stimulated Raman scattering P(crit) is approximately two orders of magnitude higher. It is concluded that these effects must be considered in the design of optical communication systems using low loss fibers.

1,080 citations


Journal ArticleDOI
TL;DR: In this paper, a set of coupled-mode equations is derived to describe mode propagation in uniform and slightly nonuniform cylindrical optical-fiber systems, and the coupling between fibers of an array made up of n identical fibers each at the vertex of a polygon and one at the center, which is not necessarily the same as its n neighbors, is determined.
Abstract: A set of coupled-mode equations is derived to describe mode propagation in uniform and slightly nonuniform cylindrical optical-fiber systems. The coupling between fibers of an array made up of n identical fibers each at the vertex of a polygon and one at the center, which is not necessarily the same as its n neighbors, is determined. Examples of this array are two fibers, three fibers in a row, and a hexagonal array with a fiber in the center. Very simple expressions for the coupling coefficients are presented. Mode coupling on a lossy fiber is investigated and a simple expression for the loss of a HE11 mode is given.

695 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the relationship between loss, coupling, and delay differences among the modes of multimode fibers and provided a comprehensive description of the interrelations between them.
Abstract: Loss, coupling, and delay differences among the modes of multimode fibers influence their transmission characteristic in a complicated way An approximation of the modes by a continuum leads to a comprehensive description of these interrelations We relate the mode power distribution to the far-field output and calculate these distributions as functions of the fiber length and the input We report measurements of the far-field distributions at various lengths of a cladded low-loss multimode fiber A comparison of theory and experiment yields a quantitative estimate of the mode coupling involved We associate this coupling with random irregularities of the fiber configuration and straightness, and construct a quantitative model of such irregularities

433 citations


Patent
Herbert Blades1
30 Jun 1972
TL;DR: In this paper, high strength, high modulus fibers having a density of at least 1.4o g/cm and consisting essentially of poly(p-phenylene terephthalamide) of inherent viscosity of at at least 4.0 are provided.
Abstract: High strength, high modulus fibers having a density of at least 1.4o g./cm.3 and consisting essentially of poly(p-phenylene terephthalamide) of inherent viscosity of at least 4.0 are provided. These fibers have a lateral birefringence of at least 0.022, a novel crystalline structure with crystalline regions having an apparent crystallite size of greater than 58 Angstrom units (A), and an orientation angle no greater than 13* with the proviso that the ratio of the apparent crystallite size to the orientation angle (degrees) is at least 6A/degree.

186 citations


Journal ArticleDOI
TL;DR: In this article, the linear and circular birefringent properties of low-loss single-mode glass fibers are found to depend upon length, and some anomalous behavior can be explained in terms of properties varying locally along the fiber and a resultant upper information rate of over 1012bits/s is estimated.
Abstract: The linear and circular birefringent properties of low-loss single-mode glass fibers are found to depend upon length. Depolarization is about 1 percent/km. Some anomalous behavior can be explained in terms of properties varying locally along the fiber and a resultant upper information rate of over 1012bits/s is estimated. Very small stress distributions or core ellipticities could give rise to the observed effects.

132 citations


Journal ArticleDOI
TL;DR: In this paper, steel fibers of various shapes (round, flat and crimped), size, and volume concentration replaced the vertical stirrups in conventional reinforced beams loaded in flexure.
Abstract: Steel fibers of various shapes (round, flat and crimped), size, and volume concentration replaced the vertical stirrups in conventional reinforced beams loaded in flexure. Shear failures were prevented by various types of fibers. The shear span ration, A/D, decreased with increasing steel fiber content. /Author/

128 citations


Journal ArticleDOI
TL;DR: In this paper, the elastic constants of carbon fiber reinforced composites were measured with an ultrasonic immersion technique and both carbon and graphite fibers were derived from both rayon and polyacrylonitrile (PAN), and had Young's moduli ranging from 6 to 80×106 psi.
Abstract: The elastic constants of carbon‐fiber‐reinforced composites have been measured with an ultrasonic immersion technique. Both carbon and graphite fibers were studied. These fibers were derived from both rayon and polyacrylonitrile (PAN), and had Young's moduli ranging from 6 to 80×106 psi. The composite elastic constants varied with fiber modulus and fiber type (carbon or graphite) but not with the fiber‐matrix bond. The fiber elastic constants c11 and c66, corrected for porosity, varied with fiber modulus but not with fiber type. The fiber constants c44 and c13 were independent of fiber modulus but varied with fiber type.

125 citations


Journal ArticleDOI
TL;DR: Prenatal development of muscle fibers was examined histochemically in the fetal lamb from 50–145 days of gestation, and it seems likely that the quantity of muscle contraction is not the major determining factor for the differentiation of these fiber types.

118 citations


Journal ArticleDOI
G. E. Walrafen1, J. Stone1
TL;DR: In this paper, Schrotter and Bofilias reported that at least 33 Raman components were observed in the 3300 > Δν> 1650 cm−1 region including shifts due to overtones and combinations, by using a slitwidth of 2 cm− 1 with a 15 m fiber length and a laser power of ∼130 mW.
Abstract: Intense spontaneous Raman radiation has been obtained from C6H6 and C2Cl, by passing the focused beam from an argon ion laser (4880 A, 5 to 250 mW) through filled hollow fused quartz optical fibers having core diameters of ∼75 μm and lengths from 10 to 25 meters. Spectral intensifications by factors of ∼102 to 103 compared to conventional sample techniques have been obtained with the fiber optics method. Raman spectra were recorded with a Cary model 81 spectrophotometer by collecting the divergent radiation emitted from the end of the optical fiber at the focus of the "image slicer." However, the intensification method is general and may be employed with any double or triple monochromator by placing the fiber end near the entrance slit. For C6H6 at least 33 Raman components were observed in the 3300 > Δν> 1650 cm−1 region including shifts due to overtones and combinations, by using a slit-width of 2 cm−1 with a 15 m fiber length and a laser power of ∼130 mW. The Raman spectra from C6H6 were found to be in good agreement with those recently reported by Schrotter and Bofilias. For C2Cl4 intense spectra were also obtained using 2 cm−1 slit-widths with fiber lengths of 25 m and power levels to 250 mW. These spectra augment those obtained earlier by Wittek and indicate five newly observed Raman and infrared coincidences that in several cases may result from the breakdown of D2h selection rules. Details of the fiber optics Raman technique are described.

109 citations


Journal ArticleDOI
TL;DR: A tentative model is proposed to account for the change in fiber length and ultrastructural organization that accompanies stretch and requires the dense bodies to be linked together into a network by the 100 A diameter filaments.
Abstract: The length-tension relationship was determined for strips of guinea pig taenia coli and correlated with the length and ultrastructural organization of the component fibers. The mean fiber length in "stretched" strips (passive ≥ active tension) was 30% greater than that for fibers in "unstretched" strips (active >> passive tension). In stretched fibers the dense bodies and 100 A diameter myofilaments were consolidated into a mass near the center of fibers in cross-sectional profile. The thick myofilaments were segregated into the periphery of the fiber profiles. In unstretched fibers the dense bodies-100 A diameter filaments and the thick myofilaments were uniformly distributed throughout cross-sectional profiles. A tentative model is proposed to account for the change in fiber length and ultrastructural organization that accompanies stretch. The basic features of the model require the dense bodies to be linked together into a network by the 100 A diameter filaments. The functional consequences of stretching the fibers are discussed in relation to the model proposed for this network.

105 citations



Journal ArticleDOI
TL;DR: In this article, the electrical resistivity, the tensile strength and the Young's modulus were found to be 1-2×10-3 ton-cm2, 4-34 ton/cm2 and 2-4×103 ton/ cm2 respectively.
Abstract: Carbon fibers are successfully grown on ceramic and/or graphite substrates through thermal decomposition of vaporized hydrocarbons at temperatures from 1100°C to 1300°C. The diameter ranges from 3 to 100 µm and the length 10 to 25 cm. Appropriate conditions for the growth of such long fibers are described. Some branched and crossed structures were observed in the fibers. Morphological and structural studies are made by means of optical microscope, scanning electron microscope, and X-ray diffraction. It leads to a conclusion that these carbon fibers are composed of cylindrical layers and scrolls of thin aromatic films aligned parallel to the fiber axis. There are two kinds of fibers with smooth and rough surfaces as illustrated in the accompanying photographs. The electrical resistivity, the tensile strength and the Young's modulus are found to be 1–2×10-3 ton-cm2, 4–34 ton/cm2 and 2–4×103 ton/cm2 respectively.

Journal ArticleDOI
TL;DR: In this article, the micromechanics of fiber composite columns under compression were investigated theoretically and the model was based on the assumption that the fiber buckles inside the matrix.
Abstract: The micromechanics of fiber composite columns under compression is investigated theoretically. The model is based on the assumption that the fiber buckles inside the matrix. In the postbuckling ran...

Patent
G Winter1, M Mansmann1, N Schon1, H Schnoring1
25 Apr 1972
TL;DR: In this article, the authors describe the production of inorganic fibers comprising a metal oxide phase and a finely divided disperse phase distributed throughout the oxide phase, the disperse phase constituting about 0.5 to 50% by weight of the fiber.
Abstract: The invention relates to the production of inorganic fibers comprising a metal oxide phase and a finely divided disperse phase distributed throughout the oxide phase, the disperse phase constituting about 0.5 to 50% by weight of the fiber. The process involves preferably dry spinning a solution in water or an organic solvent of fiber forming components which, when heated to temperature of from 500° to 1600° C either in an inert or in a reactive atmosphere, form at least two phases with a miscibility gap, of which one phase is an oxide phase containing the other phase in very finely disperse form. Preferably, the solution contains a metal salt, the anion of which contains carbon so that upon heating there is formed an oxide phase comprising the oxide of said metal having carbon dispersed therein; if carbon is not in the anion, its precursor may be an organic compound, such as a polymer, present in the solution. Other materials which may constitute the disperse phase include boron as well as carbides, nitrides, borides or silicides and some metals. The resulting fiber are of low porosity and high modulus and impart superior properties to plastics, metals, glasses and ceramics reinforced therewith.

Patent
30 Mar 1972
TL;DR: In this paper, a method of forming an article such as a light focusing fiber waveguide by applying to a substantially cylindrical starting member a layer of soot having a radially varying composition by means of flame hydrolysis is presented.
Abstract: A method of forming an article such as a light focusing fiber waveguide by applying to a substantially cylindrical starting member a layer of soot having a radially varying composition by means of flame hydrolysis. The starting member is removed and the resulting substantially cylindrical hollow cylinder is heated and drawn to reduce the cross-sectional area and to collapse the hole to form a fiber having a solid cross-sectional area with a radially varying composition.

Patent
22 Feb 1972
TL;DR: In this paper, a method of splicing optical fibers which includes placing the fibers in a V-shaped groove, slipping a pliable, metallic sleeve over the fiber ends, and then crimping the sleeve, thereby simultaneously aligning and mechanically securing the two fibers.
Abstract: Apparatus, and a method of splicing optical fibers which includes placing the fibers in a V-shaped groove, slipping a pliable, metallic sleeve over the fiber ends, and then crimping the sleeve, thereby simultaneously aligning and mechanically securing the two fibers.

Journal ArticleDOI
01 Aug 1972-Carbon
TL;DR: In this article, a study was performed on unidirectional fiber reinforced composites, prepared by the wet-winding technique using thermosetting resins or pitch as binder.

Patent
04 May 1972
TL;DR: In this paper, a yarn is manufactured by supplying a substantially non-twist strand of staple fibers to a fluid treatment zone where the staple fibers are intertwined with each other by the turbulent flow, at least part of said staple fibers having a length larger than the distance L between the fiber grasping point in the fiber feed zone and the point where the intertwinement due to turbulent flow most effectively occurs.
Abstract: A yarn having soft, attractive handle and a structure such that staple fibers are intertwined with each other to cohere into a substantially non-twist yarn. The yarn is manufactured by supplying a substantially non-twist strand of staple fibers to a fluid treatment zone where the staple fibers are intertwined with each other by the turbulent flow, at least part of said staple fibers to be supplied to the treatment zone having a length larger than the distance L between the fiber grasping point in the fiber feed zone and the point where the intertwinement due to the turbulent flow most effectively occurs.

Journal ArticleDOI
TL;DR: A probabilistic model for the tensile strength of brittle fibers is presented in this paper, where the relationship of fiber flaw structure to the statistical strength is disentangled and the relationship between the two is investigated.
Abstract: A probabilistic model for the tensile strength of brittle fibers is presented and related to present conventional testing The relationship of fiber flaw structure to the statistical strength is dis...


Patent
02 Oct 1972
TL;DR: In this paper, a slurry of anionically charged and cationically charged fibers are combined to form a discrete fiber aggregates, which is then used to form fibrous assemblies by conventional processes.
Abstract: Fibrous assemblies, such as paper, having advantageous properties related to bulk, absorbency, and compaction resistance are obtained from discrete fiber aggregates by a process which comprises contacting a slurry of anionically charged fibers with a slurry of cationically charged fibers to form said discrete fiber aggregates and thereafter forming fibrous assemblies by conventional processes.

Patent
K Boustany1, A Coran1
12 Jun 1972
TL;DR: Bonded composites of discontinuous organic fiber and vulcanized matrix are prepared by treating the fiber to reduce fiber to fiber interaction, dispersing the treated fiber and bonding ingredients into vulcanizable elastomeric matrix, and positioning the fiber therein taking suitable precautions to minimize fiber breakage during the dispersing and positioning of the fiber, and then vulcanizing the mixture to produce a bonded composite in which the organic fiber has an aspect ratio of at least about 20 but not more than about 350 as mentioned in this paper.
Abstract: Bonded composites of discontinuous organic fiber and vulcanized matrix are prepared by treating the fiber to reduce fiber to fiber interaction, dispersing the treated fiber and bonding ingredients into vulcanizable elastomeric matrix, positioning the fiber therein taking suitable precautions to minimize fiber breakage during the dispersing and positioning of the fiber, and vulcanizing the mixture to produce a bonded composite in which the organic fiber has an aspect ratio of at least about 20 but not more than about 350.

Journal ArticleDOI
01 Jun 1972
TL;DR: In this paper, a theory of coarsening for fibers of circular cross section in unidirectionally solidified eutectic alloys was developed, where fibers are assumed to be randomly distributed throughout the unoccupied space in the matrix, and diffusion of solute is assumed to occur under steady-state conditions with cylindrical symmetry.
Abstract: A theory of coarsening has been developed for the case of fibers of circular cross section in unidirectionally solidified eutectic alloys. The fibers are assumed to be randomly distributed throughout the unoccupied space in the matrix (uniformly distributed), and diffusion of solute is assumed to occur under steady-state conditions with cylindrical symmetry. The theory predicts that the cube of the average fiber radius increases linearly with time for all fiber volume fractions. As the volume fraction increases, the coarsening rate increases and the theoretical distribution of fiber radii becomes broader. It is shown that isotropic fiber coarsening occurs at approximately half the rate at which the same phase would coarsen if it were in the form of spherical precipitates for volume fractions up to 0.6. It is also demonstrated that the fibers will coarsen at a faster rate when they are uniformly distributed than when they are arranged on an hexagonal lattice.

Patent
02 Mar 1972
TL;DR: In the process of manufacturing flat fibrous structures from suspensions of fibers by depositing a suspension of such fibers onto a moving permeable surface such as an endless sieve or belt wherein the fibrous suspension has been prepared from fibrous structure formed of a plurality of fibers which have been obtained by drawing a flowing glass melt, followed by chopping of the drawn fibers to form the fiber structures of predetermined length, the improvement in accordance with the invention of preparing the fiber suspension from fiber structures obtained by directing jets of liquid onto the glass fibers drawn from the glass melt and which are being wound
Abstract: In the process of manufacturing flat fibrous structures from suspensions of fibers by depositing a suspension of such fibers onto a moving permeable surface such as an endless sieve or belt wherein the fibrous suspension has been prepared from fibrous structures formed of a plurality of fibers which have been obtained by drawing a flowing glass melt, followed by chopping of the drawn fibers to form the fiber structures of predetermined length, the improvement in accordance with the invention of preparing the fiber suspension from fiber structures obtained by directing jets of liquid onto the glass fibers drawn from the glass melt and which are being wound onto the periphery of a rotating drum in a parallel arrangement and which after a certain layer thickness thereof has been obtained are cut to a predetermined length with the fibers still being in the moistened state.

Journal ArticleDOI
TL;DR: In this paper, a reaction rate molecular model was proposed to explain some of the deformation and bond rupture behavior leading to fracture of nylon 6 fibers, and the probability of bond rupture was controlled by reaction-rate theory with a stress-aided activation energy and behavior of various loadings determined by numerical techniques.
Abstract: Electron paramagnetic resonance (EPR) techniques are used to determine the number of free radicals produced during deformation leading to fracture of nylon 6 fibers. A reaction rate molecular model is proposed to explain some of the deformation and bond rupture behavior leading to fracture. High-strength polymer fibers are assumed to consist of a sandwich structure of disordered and ordered regions along the fiber axis. In the disordered or critical flaw regions, tie chains connecting the ordered or crystalline block regions are assumed to have a statistical distribution in length. These chains are, therefore, subjected to different stresses. The effective length distribution was determined by EPR. The probability of bond rupture was assumed to be controlled by reaction-rate theory with a stress-aided activation energy and behavior of various loadings determined by numerical techniques. The model is successfully correlated with experimental stress, strain, and bond rupture results for creep, constant rate loadings, cyclic stress, stress relaxation and step strain tests at room temperature.

Patent
07 Jun 1972
TL;DR: In this article, a method of making a two-phase material comprising a mix of concrete and fibers of a material having a modulus of elasticity of at least about 20 million psi substantially uniformly distributed therein with an average spacing between fibers of up to about 0.3 inch.
Abstract: A method of making a two-phase material comprising a mix of concrete and fibers of a material having a modulus of elasticity of at least about 20 million psi substantially uniformly distributed therein with an average spacing between fibers of up to about 0.3 inch. The flexural strengths are measured for a plurality of substantially different average bond areas of the fibers per unit area in planes normal to tensile stress in test specimens of the two-phase material, and the fibers are provided and distributed in such quantity in the bulk mix that the average bond area of the fibers intersecting planes normal to the stress at known regions of highest tensile stress is sufficient to provide at least a preselected flexural strength in such regions.

Journal ArticleDOI
TL;DR: Connective tissue around the nerve cord and heart have been studied in Calpodes ethlius and it is suggested that the peroxidase activity of the fibers may be related to their stabilization.
Abstract: Connective tissue around the nerve cord and heart have been studied in Calpodes ethlius. Four components at, distinguishable by selective staining and electron microscopy: matrix, collagen fine fibrils less than 60 A in diameter and broad fibers about 400 A in diameter after glutaraldehyde only the broad fibers react selectively for peroxidase and stain with phosphotungstic acid. These fibers are most abundant in connective tissue which is elastic. The fine fibrils are arranged parallel to and between the peroxidase reaciive fibers. It is suggested that the peroxidase activity of the fibers may be related to their stabilization. The collagen fibers have the narrow fibrillar form characteristic of Lepidoptera and Coleoptera and have a macroperiod of about 660 A and a banding pattern matching that found in other insects.

Journal ArticleDOI
TL;DR: In this article, the surface area, pore diameter, and pore volume determinations were performed on representative samples of carbon fiber and fabric fabrics in a nitrogen atmosphere at 500°C for up to 4 hours.
Abstract: Phenolic textiles (fiber or fabric) were pyrolyzed in a nitrogen atmosphere at 500°C for up to 4 hr. One hour of pyrolysis gave optimum carbonization based on weight loss. The resulting carbon textiles were activated at 900°C in a carbon dioxide atmosphere for up to 31/2 hr. The level of activity attained was determined routinely by carbon tetrachloride vapor sorption. Surface area, pore diameter, and pore volume determinations were conducted on representative samples. Surface areas as high as about 2800 m2/g were attained.

Patent
Samuel Baxter1, Keith Marchant1
27 Jun 1972
TL;DR: In this article, a laminate in which one face of a fabric sheet bears a pile of flocked fibers and the opposing face is bonded to a sheet of a foamed polyolefin resin is presented.
Abstract: The invention comprises a laminate in which one face of a fabric sheet bears a pile of flocked fibers and the opposing face is bonded to a sheet of a foamed polyolefin resin. The laminates are useful as surface covering materials; e.g., carpets, upholstery and wall-coverings.

Patent
R Sara1
10 Jul 1972
TL;DR: In this article, the composites are characterized by improved thermal cycling characteristics and are produced by coating a plurality of carbon fibers first with a thin, continuous layer of nickel, and then with a second thin continuous overcoating of a metal capable of diffusing through the nickel coating and reacting with carbon to form a metal carbide; and then hot pressing the dual-coated fibers for a time and at a temperature and pressure sufficient to bond them together and diffuse at least a portion of the carbide-forming metal surface layer through the Nickel undercoating and effect reaction between said
Abstract: Composite articles having a nickel base metal matrix reinforced with a plurality of high strength, high modulus carbon fibers having a thin, intermediate layer of a metal carbide disposed upon at least a portion of the fiber surfaces. Such composites are characterized by improved thermal cycling characteristics and are produced by coating a plurality of carbon fibers first with a thin, continuous layer of nickel, and then with a second thin, continuous overcoating of a metal capable of diffusing through the nickel coating and reacting with carbon to form a metal carbide; and then hot pressing the dual-coated fibers for a time and at a temperature and pressure sufficient to bond them together and diffuse at least a portion of the carbide-forming metal surface layer through the nickel undercoating and effect reaction between said carbide-forming metal and said carbon fibers to produce a metal carbide coating on at least a portion of the surface of the fibers.