Abstract: A method for determining a resonant frequency of a mechanical device having a first mass and at least one second mass mechanically coupled to the first mass comprises the steps of: providing a control signal to a voltage-controlled oscillator (VCO) to control the frequency of an output thereof; translating a phase shifted output of the VCO into an oscillatory force which is applied to one of the first and second masses to cause the mechanical device to respond; measuring the response of the mechanical device and generating a response signal representative thereof in frequency and amplitude; generating an error signal proportional to the phase difference between a signal representative of the output of the VCO and the measured response signal; adjusting the control signal to cause the oscillatory force applied to the one mass to sweep within a calculated frequency range rendering the amplitude of the response signal to approach and exceed a calculated threshold value; and when the calculated threshold is excee

Abstract: An improved OBS based technique that monitors gas emissions from smoke stacks, tail pipes, and other sources, and that separates gas column density from thermal radiance contrast. The technique of the present invention utilizes a software generated digital filter (30) constructed to correlate with only the spectrum of gas (12) of interest, and have zero correlation with background components (22). Through using the improved OBS technique of the present invention, high performance and more positive cost effective gas monitoring systems and sensors may be built and implemented.

Abstract: A method of preparing amorphous copolymers of ethylene and at least one norbornene (NB)-type comonomer is disclosed. These polymers may be random or alternating depending on the choice of catalyst and/or the relative ratio of the monomers used. This method comprises polymerizing said monomers in a diluent or in bulk in the presence of a neutral nickel catalyst which may be represented by the formula ##STR1## wherein Y may be a saturated or unsaturated hydrocarbyl chain, X may be oxygen or sulfur, E may be phosphorus, arsenic, antimony, oxygen or nitrogen, R and R' independently each is hydrogen or a hydrocarbyl group, L is a ligand containing a heteroatom P, N or O or L and R together with L may form part of a chelating structure in which case L is an ethylenic double bond.

Abstract: The invention relates to the field of needling processes for forming fibrous preform structures. The invention is particularly useful in forming fibrous preform structures suitable for subsequent processing into high temperature resistant composite structures such as carbon/carbon aircraft brake disks. The process according to the invention compensates for fiber pull back induced by fiber resilience, and for compaction in previously needled layers induced during subsequent needling passes. According to a further aspect of the invention, Z-fiber distribution throughout the thickness of the fibrous preform structure may be manipulated as necessary to achieve a desired distribution.

Abstract: An attachable electro-impulse de-icer for de-icing an aircraft structural member includes an inductor coil disposed in proximity with the outer surface of the structural member. The coil is supported by a flexible, ice-accumulating support member (surface ply) that permits the coil to move relative to the structural member. Preferably the coil and support member are formed in an integral construction that can be attached to the leading edge of the structural member. The coil and support member are rapidly, and forcefully, displaced away from the structural member upon passing a short-duration, high-current pulse through the coil. The current flow creates an electromagnetic field that induces eddy currents in the support member (if made of metal), and the structural member (if made of metal). Upon collapse of the electromagnetic field in the coil, the support member is pulled rapidly to its rest position adjacent the structural member.

Abstract: A current monitor includes a DC isolating amplifier circuit especially adapted for adjusting the set point of a comparator. The isolating amplifier circuit includes an operational amplifier generating a first current in response to an input voltage received by the operational amplifier. The first current is transmitted to a first optocoupler and a second optocoupler which are characterized by a first CTR and a second CTR, respectively. An output of the first optocoupler is fed back to an input of the operational amplifier while an output voltage of the second optocoupler is communicated to a set point circuit. The output voltage of the second optocoupler varies as a function of the product of the input voltage of the operational amplifier and a ratio between the first CTR and the second CTR.

Abstract: An improved process for preparing 2,4,6-tris(substituted phenoxy)-1,3,5,2,4,6-trioxatriphosphorinanes is realized when the appropriate substituted-phenylphosphorodichloridite is reacted with water in the presence of a trialkyl amine wherein the alkyl groups contain 4 to 8 carbon atoms in acetone as the sole solvent, to provide the desired 2,4,6-tris(substituted phenoxy)-1,3,5,2,4,6-trioxatriphosphorinanes in increased yields and of a higher purity.

Abstract: 2-[Alkyl substituted-phenoxy]-2,3-dihydro-1,2-benzoxaphosphole 2-oxide, cyclic phosphonates prepared, for example from hindered phenols and ortho-methylolphenols, are effective heat stabilizers and antioxidants for organic materials subject to degradation by heat, oxygen and the like, and result in effective stabilizer systems when combined with hydroxyphenylalkylenyl isocyanurates.

Abstract: A tire designed for operation both as a pneumatic tire under ordinary conditions, and also without inflation under emergency conditions, has thick sidewalls made of low-hysteresis high-modulus vulcanized natural rubber composition containing reinforcing carbon black and also containing an effective anti-oxidant, together with a cobalt soap to prevent reduction in modulus during service of the tire.