Abstract: A system for determining scattering parameters (S-parameters) characterizing the behavior of a network applies a wideband stimulus signal containing multiple signal components as input to the network. The system then measures incident and reflected waveforms at all of the network's ports, digitizes and converts the measured waveforms from time domain to frequency domain data, and then computes the S-parameters values for each frequency component of interest from the frequency domain data for that frequency. The system also determines its own error coefficients (E-coefficients) for each frequency of interest from data collected during a sequence of measurements in response to either a sinusoid or a wideband signal and adjusts the computed S-parameter values accordingly.

Abstract: A method of joining a ceramic matrix composite rocket nozzle to a metal manifold is provided, wherein a silicon nitride insert is disposed inside the ceramic matrix composite rocket nozzle and the metal manifold to provide a joint therebetween. The silicon nitride insert is preferably co-processed with the ceramic matrix composite rocket nozzle such that the ceramic matrix provides a bond between the rocket nozzle and the insert. The metal manifold is then secured to the silicon nitride insert, preferably using brazing, to form a joint assembly.

Abstract: Monazite or xenotime-based blanket coatings that stiffen ceramic fabrics without causing embrittlement at temperatures of at least as high as 2400° F. are provided. Methods for making the coatings are also provided. The methods comprise the synthesis of high purity, monazite and xenotime powders with the stoichiometric ratio of metal to phosphorous of about 1:1.

Abstract: A woven preform for a ceramic composite has a plurality of layers and structural members. The plurality of layer are of woven yarns of fibrous material. The structural members extend between the layers. The layers and members define interlayer spaces. One or more of the layers may have a plurality of openings extending therethrough. Low density ceramic insulation made be deposited in the interlayer spaces via a slurry that enters the preform, or the preform after it has been made a part of a composite, through the openings. The carrier of the slurry exits the preform, leaving the randomly packed fibers in the interlayer spaces. The structural members may be walls that, along with the layers, define channels. The channels may be used to direct fluid through so as the composite functions as an insulator. The channels may be directed in the warp direction for achieving increased benefits.

Abstract: A system for determining scattering parameters (S-parameters) characterizing the behavior of a network applies a wideband stimulus signal containing multiple signal components as input to the network. The system then measures incident and reflected waveforms at all of the network's ports, digitizes and converts the measured waveforms from time domain to frequency domain data, and then computes the S-parameters values for each frequency component of interest from the frequency domain data for that frequency. The system also determines its own error coefficients (E-coefficients) for each frequency of interest from data collected during a sequence of measurements in response to either a sinusoid or a wideband signal and adjusts the computed S-parameter values accordingly.

Abstract: Thermodynamically stable ceramic composites are provided for use in high temperature reactive environments. A phosphate selected from monazites and xenotimes functions as a weak bond material in the composite. Monazite comprises a family of minerals having the form MPO.sub.4, where M is selected from the larger trivalent rare earth elements of the lanthanide series (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, and Tb) and coupled substituted divalents and tetravalents such as Ca or Sr with Zr or Th. Xenotimes are phosphates similar to monazite where M is selected from Sc, Y, and the smaller trivalent rare earth elements of the lanthanide series (Dy, Ho, Er, Tm, Yb, and Lu).

Abstract: Thermodynamically stable ceramic composites are provided for use in high temperature oxidizing environments. A phosphate selected from monazites and xenotimes functions as a weak bond interphase material between the constituents of the composites. Monazite comprises a family of minerals having the form MPO.sub.4, where M is selected from the larger trivalent rare earth elements of the lanthanide series (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, and Tb) and coupled substituted divalents and tetravalents such as Ca or Sr with Zr or Th. Xenotimes are phosphates similar to monazite where M is selected from Sc, Y, and the smaller trivalent rare earth elements of the lanthanide series (Dy, Ho, Er, Tm, Yb, and Lu).

Abstract: A magnetic switch for recording the change in position of a magnetic field includes a first object on which is positioned a source of magnetic force for creating a magnetic field and a second object on which is positioned at least one type II superconducting medium. The type II superconducting medium exhibits a permanent magnetic component after exposure to a magnetic field, such that relative motion between the first object and the second object causes the magnetic field to induce a residual magnetization in the superconducting medium.

Abstract: In a Ce-ZrO.sub.2 -based laminar composite having enhanced fracture toughness, alternating barrier layers comprise a ceramic material that undergoes stress-induced phase transformation, if any, less readily than Ce-ZrO.sub.2. Separation of the barrier layers is normally in the range of about 10-200 .mu.m, with optimum individual barrier layer thicknesses at the lower end of the range. Powders of ceramic materials comprising the individual layers of the composite are dispersed in separate slurries. The pH of the slurries is adjusted to form coagulations in which the particles settle without mass segregation and can be consolidated to high density by centrifuging. After centrifuging, the supernatant liquid can be removed and a desired volume of another slurry can be added on top of the first layer of consolidated material. This process can be repeated indefinitely to form a consolidated structure having individual layers as thin as approximately 10 .mu.m.

Abstract: Thermodynamically stable ceramic composites are provided for use in high temperature oxidizing environments. The composites comprise high strength alumina fibers (Al.sub.2 O.sub.3) in a ceramic matrix. The ceramic matrix comprises material similar to the fibers to improve compatibility of the composite materials. A material selected from the .beta.-alumina and magnetoplumbite family of materials is used to provide a weakly bonded interface between the fibers and the ceramic matrix. .beta.-aluminas and magnetoplumbites have weak layers as an intrinsic characteristic of their crystal structure, which comprise spinel layers (basically Al.sub.2 O.sub.3) separated by very weakly bonded planes containing the .beta.-forming ions. The weak planes of these materials allow preferential debonding and sliding, and thus inhibit crack growth across the interface between the fibers and the ceramic matrix. The alumina fibers can be coated with .beta.

Abstract: A tunable electromagnetic filter includes a type II superconducting medium which exhibits a permanent ferromagnetic component after exposure to a magnetic field. A magnetic field passes through the medium in a first direction, while an input conductor wound around the medium in a second direction perpendicular to the first direction receives an input signal, and an output conductor is wound around the medium in a third direction perpendicular to the first and second directions. At resonance of the medium, an alternating field magnetic component perpendicular to both the incoming signal and the magnetic field is created to induce a current of the resonant frequency in the output conductor.

Abstract: The present invention relates to an article having improved physical properties as compared to the individual components, which article comprises:a laminated ceramic fiber composite of alternating layers of discrete thin solid sheets of ceramic A having a substantially large upper and lower surface bonded to discrete thin sheets B comprising fibers and having large upper and lower surfaces using a suitable bonding agent.

Abstract: A device is provided for suspending an external load by means of a magnetic field and a superconductor. The superconductor is supported in a magnetic field which penetrates the superconductor. A magnet is suspended below the superconductor and oriented so that its magnetic moment is aligned parallel to the magnetic field. The magnet is provided with a coupling means so that it can be coupled to an external load. Either a vertical or a horizontal magnetic field can be used. In one embodiment, the load-carrying member is a composite material suspended from a supported magnet. The composite consists of a superconducting phase and an attractive phase comprising either a magnet, a ferromagnetic material, or a paramagnetic material. In another embodiment, a device for concentrating flux is provided by placing a superconductor between the source of the magnetic field and the position in which the concentrated flux is desired.