General Electric Company

US Government As Represented by the Secretary of the Army

Martin Marietta Corporation

Moayyed A Hussain

Kai-Bor Yu

Kenneth Wayne Rigby

David J Murrow

Koeunyi Bae

William A Edelstein

John F Schenck

Mark A Johnson

Julius Frankel

Edward J Troiano

Bryon Knight

Linda Ann Itani

Jeffrey Braunstein

A simple, inexpensive, and fast method of establishing if a defect does or does not exist within a thick-walled solid geometry, which is especially useful to detect if such a defect, a crack, exists within a gun barrel. With further analysis, the method allows not only the identification of the defect's presence; but, a means of establishing the size thereof&#x2014;which, for example, is critical to understanding if a gun tube has a defect that would warrant its being taken out of service for the safety of its crew or removed from manufacturing. The method involves creating an acoustic vibration in the particular thick-walled, solid geometry, esp. a gun barrel, and observing the vibration pattern which results. The size of the particular defect can be ascertained by a) manually using a correlation between the magnitude of the defect and the relative changes in the decay coefficient or shifts in frequency data or (b) automatically using a Bayes maximum likelihood, statistical pattern classification algorithm and a library comprised of either the decay coefficients or the means and covariances of defect-free and cracked objects.

Crack detection in thick-walled cylinders

The present invention is a nondestructive and quantitative laser ultrasonic laser apparatus and associated method for determining adhesion quality of a coating on a substrate. The apparatus of the invention is preferably a pulsed laser for generation and Michelson-type interferometer based system and includes a rotary probe head assembly for making evaluations within a cylindrical test specimen. The method of the invention includes data analysis that uses acquired data from the ultrasonic laser apparatus and computes the dispersion relation or curves (frequency versus velocity) using a ridge-following technique in wavelet analysis and from this, outputs the adhesive quality of the coating by comparing it with a theoretically based determination of a particular coating/substrate bond system. The invention is used for evaluating adhesion quality of coatings used in a gun bore.

Nondestruction coating adhesion evaluation using surface ultrasonic waves and wavelet analysis

An ultrasonic imaging system employs a thinned array of transducer elements in order to reduce the number of signal processing channels. The transducer elements are reduced in number and then selectively located at grid positions in a pattern which reduces the sidelobe levels produced by the array. Thinning is accomplished by discretizing the aperture of the transducer array in two steps. First, a continuous aperture is discretized as a set of concentric rings. Then each ring is replaced by a set of spaced transducer elements. A zero sampling technique is used to determine the number of elements on each ring.

Sparse two-dimensional wideband ultrasound transducer arrays

In a digital ultrasound imaging system, artifacts due to spurious ultrasound reflections from a highly reflective object outside the region of interest are reduced in magnitude by apparatus included in the beamforming system of the digital imaging system. A null is formed in a specified direction in the ultrasound beam patterns by perturbing the time delay on each receive channel. After estimating the direction of the highly reflective, interfering object and computing a time delay perturbation using a very fast algorithm, a null approximately 10 dB deep is introduced into each beam in the direction of the interfering object. This null reduces the magnitude of artifacts in the image, thereby providing image enhancement.

Ultrasound image enhancement using beam-nulling

An active array antenna for use, for example, in a radar system, includes elemental antennas, each with a T/R module, distributed over a circular aperture. For lowest cost, the aperture is thinned. The T/R modules are operated at maximum output, to achieve maximum DC-to-RF efficiency, and for simplicity. A phase controller controls the phase shift which is imparted by each module to its signal, to form a main beam and its associated sidelobes. A perturbation phase generator portion of a phase controller adds a perturbation phase shift selected, in conjunction with a particular thinning distribution, to form a relatively wide null in the sidelobe structure, in which signal transduction is reduced. In a radar context, this null may be placed on a source of ground clutter or a jammer.

Clutter suppression for thinned array with phase only nulling

A nonrectangular antenna aperture is provided comprising four quadrants for receiving electromagnetic signals. The aperture has the capability to form a predetermined sum beam, a predetermined first difference beam, a predetermined second difference beam, and a predetermined double difference beam so that the product of the first and second difference beams is substantially equal to the product of the sum and the double difference beams.

Antenna aperture with mainlobe jammer nulling capability

An antenna beamformer is provided for coupling to a circular antenna aperture comprising a plurality of vertical beamformers and four horizontal beamformers coupled to the vertical beamformers so that each horizontal beamformer has the capability to form a different predetermined electromagnetic field radiation pattern.

Antenna beamformer

In the production of nuclear magnetic resonance images, it is necessary to provide various magnetic fields with specified orientations and configurations in particular relationships with respect to a cylindrical coil form on which the RF and gradient coils are generally disposed. In particular, it is necessary to produce so-called transverse gradient fields which are oriented transversely with respect to the cylindrical form. It is necessary to produce a component parallel to the axis of the cylinder, but which component varies linearly in intensity in the direction transverse to the axis. That is to say, it is desirable to produce a magnetic field component within the cylinder such that surfaces on which this component is constant are parallel and are generally oriented parallel to the axis of the cylinder. Furthermore, for the purpose of providing proper spatial definition and resolution, it is necessary that this transverse field exhibit a highly linear variation in intensity inside the cylinder. In a nuclear magnetic resonance imaging system, two such coil sets are required and are oriented at right angles to one another so as to generate x-axis and y-axis positioning information. The present invention describes coil winding patterns which are capable of producing such transverse gradient magnetic fields with an exceedingly high degree of linearity.

Growing community of inventors

Menands, NY, United States of America

Moayyed A Hussain