Abstract: Implementations relate to selection of a physics-specific model for determination of characteristics of radio frequency signal propagation. In some implementations, a method includes receiving a plurality of first propagation characteristics of a radio frequency (RF) signal, determining a feature vector based on the first propagation characteristics, inputting the feature vector to a machine-learning meta-model, and executing the machine learning meta-model to select a particular physics-specific model from multiple physics-specific models, where each of the physics-specific models is for a different RF signal propagation environment. The feature vector is input to the particular physics-specific model, and the particular physics-specific model is executed to output an estimate of one or more second propagation characteristics of the RF signal based on the feature vector.

Abstract: A space vehicle has two stages: one containing an air motor; the other containing a rocket propellent motor. After the space vehicle has been launched, flexible wings such as parafoils can be used to recover stages of the space vehicle. In addition, flexible wings such as a parafoil can be used to aid in the delivery payload in the second stage into its orbital state.

Abstract: Textile length multifilament bundles of coated and bonded glass fibers are fed into the fiber inlet of a momentum exchange aspirator having a high pressure propelling air source inlet providing propelling air at a velocity generally equal to the velocity of sound to cause flow of air to carry the bundles into the aspirator fiber inlet and produce a turbulent flow zone which destroys the interfiber bonds, without destroying the protective coating on the fibers and with minimum fiber breakage, to form a high velocity stream of discretely separated textile length coated glass fibers at the aspirator outlet.

Abstract: A nonwoven fabric having alternating stripes of high fiber density and low fiber density is made in such a manner that the high fiber density stripes run across the fabric and maximize the cross direction strength to a point that the cross direction/machine direction strength ratio approaches unity. This advantageous and desirable characteristic can be achieved by hydroforming a card web, by disposing the carded web on a relatively fine mesh screen and placing a finger-like striping bars over the web with the axis of the bars at 90.degree. to the card web's general fiber orientation. Water was then sprayed over the assembly with sufficient force to rearrange the fibers in the web thereby producing the nonwoven fabric of this invention.

Abstract: A nonwoven fabric having alternating stripes of high fiber density and low fiber density is made in such a manner that the high fiber density stripes run across the fabric and maximize the cross direction strength to a point that the cross direction/machine direction strength ratio approaches unity. This advantageous and desirable characteristic can be achieved by hydroforming card web; first disposing the carded web on a relatively fine mesh screen and placing a finger-like striping bars over the web with the axis of the bars at 90.degree. to the card web's general fiber orientation. Water was then sprayed over the assembly with sufficient force to rearrange the fibers in the web thereby producing the nonwoven fabric of this invention.

Abstract: A nonwoven fabric having alternating stripes of high fiber density and low fiber density is made in such a manner that substantially all of the fibers in the stripes of high fiber density are oriented in substantially one direction, for example the machine direction, while substantially all of the fibers in the adjacent stripes of low fiber density are oriented in a direction substantially normal to that direction. This phenomenon can be produced by passing a fluid-borne stream of discretely separated fibers over a set of finger-like striping bars that are disposed, equidistantly from each other, directly over a moving conveyor screen or by a set of impervious resist areas in the shape of bars, or the like, disposed directly on the moving screen.

Abstract: An unlayered nonwoven fabric has a uniformly repeating pattern of high fiber density areas, each surrounded by low fiber density areas. The low fiber density areas inconnecting the high fiber density areas are composed of substantially parallelized strands of fibers entering into the high fiber density areas from at least eight directions. These octadirectionally oriented nonwoven fabrics have advantageous tear characteristics, and by the nature of the uniform cover factor of the web, they have many desirable and advantageous uses.

Abstract: A novel battery separator for a flat-pack or planar battery is disclosed wherein a nonwoven fabric is disposed on and across a plastic frame or grid, the outer edges of the fabric being disposed on said plastic frame are of extremely low fiber density and being oriented predominantly in a direction normal to each side of the frames so as to facilitate the more complete thermal pressurized bonding of a stack of separators and similarly electrodes by a sealing of the outer edges of the respective plastic frames. A more complete seal is thus formed insuring against the leaking or escaping of the liquid electrolyte contained therein.

Abstract: A nonwoven fabric having alternating stripes of high fiber density and low fiber density is made in such a manner that the high fiber density stripes run across the fabric and maximize the cross direction strength to a point that the cross direction/machine direction strength ratio approaches unity. This advantageous and desirable characteristic can be achieved by hydroforming a card web, by disposing the carded web on a relatively fine mesh screen and placing a finger-like striping bars over the web with the axis of the bars at 90.degree. to the card web's general fiber orientation. Water was then sprayed over the assembly with sufficient force to rearrange the fibers in the web thereby producing the nonwoven fabric of this invention.

Abstract: Air-laid fibrous webs are formed from randomly-oriented mixed fibers containing a minor proportion of short, flock-length, thermoplastic and thermoretractile fibers. The air-laid web is then heated, without pressure, to cause melting of the thermoplastic fibers to the point of substantially complete loss of fiber identity. The relative orientation of the web thus formed is stabilized so that the fibers therein maintain their general positional relationships through subsequent stresses incurred during the operations of printing, saturating, drying, winding into roll form and the like.

Abstract: A nonwoven fabric having alternating stripes of high fiber density and low fiber density has fibers of at least 1/2 inch in length and fibers of less than 1/2 inch in length, preferably under 1/4 inch in length. The fabric is made in such a manner as to produce parallel twistless ribbon strands in the high fiber density areas containing both short and long fibers. The twistless ribbon strands are bridged together by the long fibers so as to form the nonwoven fabric. A majority of the bridging long fibers have at least a portion of their length included in adjacent twistless ribbon strands; said ribbon strands having at least one strand width space between said ribbon strands.

Abstract: A method of making a nonwoven fabric having alternating stripes of high fiber density and low fiber density is described wherein substantially all of the fibers in the stripes of high fiber density are oriented in substantially one direction, for example the machine direction, while substantially all of the fibers in the adjacent stripes of low fiber density are oriented in a direction substantially normal to that direction. This phenomenon can be produced by passing a fluid-borne stream of discretely separated fibers over a set of finger-like striping bars that are disposed, equidistantly from each other, directly over a moving conveyor screen by a set of impervious resist areas in the shape of bars, or the like, disposed directly on the moving screen.

Abstract: An elastic dampening roll cover knitted in the form of a tubular sleeve comprising knitted courses and wales of inelastic absorbent yarn, with an elastic yarn interlaced with the courses and wales around the circumference of the tubular sleeve, said inelastic absorbent yarn comprising a substantially inelastic air-bulked yarn having a plurality of substantially continuous filaments which are individually convoluted into coils, crunodal loops and whorls at random intervals along their length and the surface of said yarn having a plurality of crunodal loops irregularly spaced therealong, said elastic yarn comprising an elastic core strand and a wrapping strand associated with the elastic core strand in the form of doubled-back loops wound with false twist for a multiplicity of turns around the circumference of the elastic core strand.

Abstract: A nonwoven fabric having alternating stripes of high fiber density and low fiber density has fibers of at least one-half inch in length and fibers of less than one-half inch in length, preferably under one-fourth inch in length. The fabric is made in such a manner as to produce parallel twistless ribbon strands in the high fiber density areas containing both short and long fibers. The twistless ribbon strands are bridged together by the long fibers so as to form the nonwoven fabric. A majority of the bridging long fibers have at least a portion of their length included in adjacent twistless ribbon strands; said ribbon strands having at least one strand width space between said ribbon strands.

Abstract: A nonwoven fabric having alternating stripes of high fiber density and low fiber density is made in such a manner that substantially all of the fibers in the stripes of high fiber density are oriented in substantially one direction, for example the machine direction, while substantially all of the fibers in the adjacent stripes of low fiber density are oriented in a direction substantially normal to that direction. This phenomenon can be produced by passing a fluid-borne stream of discretely separated fibers over a set of finger-like striping bars that are disposed, equidistantly from each other, directly over a moving conveyor screen or by a set of impervious resist areas in the shape of bars, or the like, disposed directly on the moving screen.