Showing papers by "General Dynamics published in 1987"

Computer generated holograms: an historical review

Abstract: Since Gabor's first hologram, the meanings of that term have grown with increased use of the invention. Computers expanded applications further, and this paper surveys the methods and techniques of computer generated holograms.

A Chi-square test for fault-detection in Kalman filters

Abstract: A test for real-time detection of soft failures in navigation systems using Kalman filters has been proposed by Kerr. The test is based on the overlap between the confidence regions associated with two estimates, one obtained from a Kalman filter using on-line measurements, and the other based solely on a priori information. An alternate computational technique is presented which is based on constructing a chi-square test statistic from the difference between the two estimates and comparing it to a precomputed threshold. The chi-square test avoids the iterative computations required by the two-ellipsoid method for dimensions of two and higher.

An experimental and analytical treatment of matrix cracking in cross-ply laminates

Abstract: The development of damage in cross-ply Hercules AS4/3502 graphite/epoxy laminates has been investigated. Specific endeavors were to identify the mechanisms for initiation and growth of matrix cracks and to determine the effect of matrix cracking on the stiffness loss in cross-ply laminates. Two types of matrix cracks were identified. These include both straight and curved cracks. The experimental study of matrix crack damage revealed that the curved cracks formed after the straight cracks and followed a repeatable pattern of location and orientation relative to the straight cracks. Therefore, it was postulated that the growth mechanism for curved cracks is driven by the stress state resulting from the formation of the straight cracks. This phenomenon was analytically investigated by a finite-element model of straight cracks in a cross-ply laminate. The finite-element results provide supporting evidence for the postulated growth mechanism. The experimental study also revealed that the number of curved cracks increased with the number of consecutive 90-deg plies. Finally, experimental results show as much as 10-percent degradation in axial stiffness due to matrix cracking in cross-ply graphite/epoxy laminates.

Point focus solar concentrator using reflector strips of various geometries to form primary and secondary reflectors

Abstract: A point focus solar concentrator which uses various geometries of cylindrical reflector strips some of which are tilted to simulate a point focus by overlaying the line focii of each segment at a coincident point Several embodiments of the invention are disclosed that use cylindrical parabolic, cylindrical hyperbolic or flat reflector strips to concentrate incident solar energy for use by a solar dynamic engine located at the focal point Also disclosed is a combined photovoltaic/solar dynamic engine concentrator energy system that uses this arrangement of mirrors

A Fault-Tolerant Multisensor Navigation System Design

Abstract: The problem of soft-failure tolerant estimation in navigationsystems composed of multiple inertial measurement clusters and oneor more reference sensors is addressed. A new approach ispresented that achieves containment of failed sensor data, andisolates the historic good data provided by the unfailed sensors.Multiple (local) estimates are computed where the estimates areconditioned on different subsets of the sensors. A statistical overlaptest is used to determine the validity of the local estimates, and afailed sensor can be identified from analysis of the invalid localestimates. After the time of detection the most accurate estimatebased on all but the failed sensor is identified. The results areapplied to a dual-inertial/Doppler radar navigation system andsimulation results are presented.

Loading Rate Effect on Interlaminar Fracture Toughness of a Thermoplastic Composite

Abstract: A study was undertaken to investigate the loading rate effect on delamination fracture initiation toughness of a thermoplastic composite. For this purpose, double cantilever beam specimens of graphite/PEEK were tested in a displacement controlled mode using an Instron tensile test machine. Specimens were loaded at various crosshead speeds ranging from 0.05 cm/min to 100 cm/min. The interlaminar fracture toughness was found to decrease with increasing loading rate, and this decrease was more than one hundred percent over the five decades of loading rate employed.

Flexible VLSI on-chip maintenance and test system with unit I/O cell design

Abstract: This application describes a peripheral cell structure for VLSI chips that requires the use of standard cells having both input and output capability connected to nearly all of the signal carrying pins. The cells function is alterable (to input or output and to where the data input signals originate) by control signals which may originate with a control register. The clock input signal is split into two independent signals to selectively disable the input or output registers, thus allowing the control register to be changed without affecting the contents of the other two registers. An early signal is also provided to prepare for mode changes.

Selection of Degrees of Freedom for Dynamic Analysis

Abstract: A technique for the selection of dynamic degrees of freedom of large, complex structures for dynamic analysis is described and the formulation of Ritz basis vectors for component mode synthesis is presented. Generally, the selection of DDOF is left to the judgement of engineers. For large, complex structures, however, a danger of poor or improper selection of DDOF exists. An improper selection may result in singularity of the eigenvalue problem, or in missing some of the lower frequencies. This technique can be used to select the DDOF to reduce the size of large eigenproblems and to select the DDOF to eliminate the singularities of the assembled eigenvalue problem of components mode synthesis. The execution of this technique is discussed in this paper. Examples of using this technique in conjunction with a general purpose finite element computer program are given.

Adaptive matched filter

Abstract: An apparatus provides matched filter output characteristics for known signals embedded in noise signals that have varying noise power distributions. The system correlates applied signals with a manipulated version of the applied signals in an analog-to-analog correlator. The manipulated signals are derived by Fourier transforming the applied signals and estimating the noise power spectral density. A filter transfer function is then calculated using the noise power estimates and stored information related to the characteristics of the known signal. The transfer function is then inverse Fourier transformed to provide a filter impulse response characteristic which is correlated with the applied signals. A method of processing applied signals to provide for an enhanced signal-to-noise ratio for varying noise power distributions is also disclosed.

Method of and apparatus for generating hydrogen and projectile accelerating apparatus and method incorporating same

Abstract: A projectile is accelerated through a barrel by a high pressure hydrogen gas jet that is derived by exothermically reacting water or a water-hydrogen peroxide liquid mixture with metal or a metal hydride. The temperature of the reaction is controlled by controlling the power in a plasma discharge applied to a reaction chamber containing the liquid and particles of the metal or metal hydride. A non-vaporous metal oxide resulting from the reaction is centrifugally separated from the hydrogen that drives the projectile.

Jettisonable protective cover device

Abstract: An in-flight jettisonable protective cover device for protecting fragile, accurate, radomes or signal-responsive components for the major portion of a flight which is capable of being jettisoned in one piece at supersonic speeds from a guided missile, other air vehicles, or space vehicles. The cover device is for use, for example, in combination with a guided missile having a shell structure, a nose portion, and a radome in the missile nose. The cover device is attached to the missile nose for covering the radome such that an inner space is defined. A plurality of shear pins or other quick-release mechanisms attach and retain the cover device to the missile shell. A source of low pressure gas pressurizes the inner space to approximately 50 psi. A rapid-discharging, high pressure gas cartridge produces a high pressure gas for exerting a pressure force on the aft face of the cover device. The pressure forces are sufficient to shear the retaining pins and accelerate the cover device sufficiently forward to clear the missile body at supersonic speeds. The missile angle of attack creates lateral aerodynamic forces on the cover deivce to clear it from the missile. The sensitive radome can then be used for high precision detection and tracking as required at intercept.

Bell housing sealing assembly for mounted connector

Abstract: A sealing assembly for protecting the exposed components of a mounted electrical connector from the environment provides a seal between a connector backshell and a mounting plate to which the connector is mounted. The bell housing sealing assembly generally comprises a tubular member having a bottom end and a top end, the member being of sufficient inside diameter and length for surrounding an electrical connector having a backshell between the connector backshell and a mounting plate to which the connector is mounted; a top seal for sealing between the top end of the tubular member and the backshell of the surrounded connector; and a bottom seal for sealing between the bottom end of the tubular member and the mounting plate. The sealing assembly is threadably attached to either the connector backshell or, preferably, to the receptacle mounting nut. A second embodiment employs a force fit double lip seal as a top seal.

Soft decision digital communication apparatus

Abstract: An apparatus for performing a soft decision function prior to convolutional decoding in a data communication system using differential quadrature-PSK or other transmission schemes is disclosed. A memory element coupled between a demodulator and the convolutional decoder in a receiver portion of the communications system performs the soft decision function. The memory element contains data organized using probability of occurrence and Log-Likelihood parameters for each potential combination of current and past received signal modulation quantized at a predetermined level.

Software reuse and simulation

Abstract: Software reuse technology has the potential of impacting significantly the software development process. This paper addresses issues of software reuse and their application to simulation software. A simple classification scheme is presented to assist in the identification of software components. Historical approaches to reuse are then discussed along with desirable attributes of reuse systems and components. Following this, impacts of reuse technology on the software development process are discussed. The paper concludes with sections on the application of reuse to simulation and a methodology for developing reuse systems.

Rocket exhaust deflector

Abstract: A missile canister hatch cover is provided which deflects the rocket exhaust from an adjacent uptake channel away from a missile as it leaves the canister. After diverting the uptake exhaust flow away from the missile, the hatch cover is returned to its closed position by the missile rocket exhaust as the missile nozzle clears the canister opening. Overall wear and tear on the launching system from the rocket exhaust is reduced and the uptake flow plume is stopped from expanding above the launcher. During missile launch the hatch cover is unlatched and spring loading opens it more than 90° to a locked position where it interferes with the exhaust flowing from the uptake. The interference deflects the uptake flow away from the missile during flyout to avoid the heating, side thrusts, and contamination associated with the uptake exhaust flow field. After the missile clears the canister and the rocket exhaust begins to impinge on the hatch cover, the hatch cover is unlocked from its open position by actuation of a drag flap that is deployed to help close the hatch cover. An ablative material is applied to exposed surfaces of the hatch cover to prevent heat damage while it is deflecting the uptake exhaust flow.

Compensation circuitry for dual port phase-locked loops

Abstract: Phase port gain compensating circuitry is coupled to the phase modulation summing circuit and voltage controlled oscillator (VCO) gain compensating circuitry is coupled to the frequency control terminal of the VCO. Compensator control circuitry utilizes divider ratio control information to control the characteristics of the two compensators to compensate for otherwise undesirable effects on the phase-locked loop response parameters caused by changes in the divider ratio and in the VCO gain.

Drive system for track-laying vehicles

Abstract: A drive system for track-laying vehicles utilizes a pair of separate and independent motors (M1, M2) to drive a multi-range, infinitely variable steering transmission pursuant to developing two track driving transmission outputs. The transmission includes a pair of interconnected output planetary gears sets (20, 20) which are separately driven by the two motors to develop first range forward and reverse propulsion and steering at the transmission outputs (32, 34) as sun to carrier reductions. The transmission is shiftable into a second, higher speed range, wherein the two motor outputs are combined in one (30) of the output planetary gear sets constructed to produce second range forward propulsion and steering power, as well as steer canceallation at the transmission outputs.

Explosive vaporization of aerosol drops under irradiation by a CO(2) laser beam.

Abstract: Experimental results on the explosive breakup of water aerosols in response to high-energy CO(2) laser radiation are presented for optical size parameters ranging from 6 to 15. The maximum power density used in this work was ~1.5 MW/cm(2). A pulsed N(2) laser imaging system coupled to a digital image processing system was used to observe visually the behavior of the drops on breakup. A phase/Doppler particle analyzer system was used to determine the simultaneous size and velocity of expelled particles at a distance of 2 mm from the drops. Results indicate that the incident irradiance affects the average size of particles expelled, but the average velocity of the expelled particles is not a strong function of the incident irradiance. Drop explosions resembling jellyfish are reported, we believe, for the first time in this work.

Solar simulator employing flexible-optics

Abstract: The solar simulator of the invention comprises a source of high intensity light simulating as closely as possible the spectral radiance of the sun directed through a flexible optic light guide into a chamber and pressure sealed through a chamber wall where this light is then directed on to a test specimen in a column or otherwise. The high intensity light is provided by one or more illuminating sources which can be positioned at the distal end or ends of the fiber optics or embedded within a fiber or liquid optic core.

Processing system for performing matrix multiplication

Abstract: An optical processing system for performing a matrix multiplication Mx where M is a matrix and x is a vector involves two two-dimensional arrays of optically transmissive elements with each element of the first array communicating light to the corresponding elmement of the second array. The optical transmittance of each row of one of the arrays is controlled according to the values of the vector x, and the optical transmittance of each element of the other array is controlled according to the corresponding matrix value m(i,j). The first array is uniformly illuminated and the amount of light transmitted through the two arrays is detected by a suitable array of photodetectors. The output of each photodetector will be proportional to the sum of the products of the vector x(i) with each value of the matrix in the corresponding column of the matrix array.

Explosively driven power supply

Abstract: A permanent magnet made of a pulverizable magnetic material is positioned immediately adjacent to a quantity of an explosive. An electrically conductive coil surrounds the permanent magnet and the explosive. A detonator is provided for detonating the explosive. The explosive is capable, upon detonation, of rapidly removing the magnet from inside the coil by disintegration, by collapsing the magnet or by causing high velocity omni-directional dispersal of a plurality of minute fractional parts of the permanent magnet. A single-pulse high voltage electrical signal is thereby induced in the coil.

Switching logic driver with overcurrent protection

Abstract: A logic driver having control circuitry for receiving an input bistate data bit and providing power at an output at first and second predetermined voltage levels when an input bistate data bit is respectively of first and second states. Sensing circuitry is coupled to the control circuitry for detecting the level of current at the output and providing a corresponding current level indication. The driver further includes overcurrent circuitry, responsive to the current level indication, for generating an overcurrent command when the output current exceeds a predetermined level. The control circuitry is responsive to the overcurrent command for disabling the output of power at the corresponding predetermined voltage level at the output.

Mid-symbol sampling timing estimator

Abstract: A timing error estimator which samples a received stream of data symbols at the beginning, end, and a mid-point of a symbol period is disclosed. These samples are used with a model that assumes that a data stream waveform should transition along a straight line between its values at optimum sampling instances, separated by the symbol period. Differences between a mid-symbol sample estimated using this straight line model and the actual mid-symbol sample are assumed to be due to a timing error. The timing error estimator preforms computations on complex inputs and therefore is compatible with a wide variety of modulation types.

Rocket exhaust recirculation obturator for missile launch tube

Abstract: A rocket exhaust recirculation obturator or cover member is designed to extend across the base of a missile in a launch tube between the exit nozzle of the missile rocket exhaust and the walls of the launch tube. The cover member has a central opening which seals against the rocket motor nozzle exit, and an outer periphery which seals against the launch tube walls. During launch, pressure of exhaust gases recirculating back up the launch tube will urge the obturator against the base of the missile, and both the missile and obturator will accelerate together up the launch tube. A release assembly is provided at the upper end of the launch tube which engages corresponding release devices at the outer periphery of the obturator. The engagement releases the pressure bond between the obturator, the missile base, and the launch tube. This allows the rocket exhaust to impinge upon the upper surface of the obturator in opposition to the obturator's momemtum. The exhaust impingement forces the obturator back down the launch tube, eliminating debris outside the launch tube.

Pulse synthesizing network and method

Abstract: A pulse forming network, responsive to a DC power supply, supplies predetermined current waveforms to a load in response to commands from a programmed source. Plural inductors are connected to switches responsive to commands from the programmed source. The switches are controlled to couple the inductors to the DC source to charge the inductors to a predetermined current level that is maintained substantially constant. The predetermined current level in each inductor is supplied to the load by switches controlled by the programmed source so that during successive intervals the predetermined constant current levels from differing numbers of the inductors flow from the inductors to the load. The inductance of each inductor, the load impedance and the duration current is supplied to the load by the inductors are such that the predetermined current level supplied by each inductor to the load is maintained relatively constant.

System including a portable heat gun for curing advanced composite workpieces

Abstract: A system for curing advanced composite workpieces including a portable heat gun that provides a flow of heated air against a workpiece. The heat gun is controlled to direct a flow of heated air against an advanced composite workpiece at a predetermined temperature for a predetermined time period and upon cessation of the time period to thereafter direct an unheated flow of air against the advanced composite for a second period of time thereby causing a resin component of the advanced composite to flow within the composite in a prescribed manner and to cure to a desired hardness.

Infinitely variable steering transmission

Abstract: An infinitely variable steering transmission is constructed to utilize the unidirection, continuous outputs of a pair of traction drive units for accelerating and decelerating a track-laying vehicle through a first forward and reverse propulsion range and a plurality of higher forward propulsion ranges and for developing steering power in all ranges. The transmission includes a pair of interconnected output planetary gears sets and a single input planetary gear set for combining the traction drive unit outputs and the constant speed input from a suitable prime mover for first and third range propulsion and steering power. Second range propulsion and steering power is obtained exclusively from the traction drive units in a manner to also provide steer cancellation, a continuous drive unit stroking pattern, and synchronous range shifting.

Fastener collar removal tool

Abstract: A tool for removal of round internally threaded collars from high efficiency aerospace fasteners. The tool includes a central cylindrical pin having a head at one end held against rotation, a non-round extension at the second end and a transverse bore intermediate the ends, containing a ball which is spring biased to project slightly beyond the pin wall. A mandrel assembly surrounds the pin and is rotatable relative thereto. A gripping collet is positioned between the mandrel and pin with collet fingers at one end extending beyond the mandrel and a threaded second end threaded into said mandrel. An axial slot in said collet is adapted to receive said ball when aligned therewith to form a releasable latch mechanism. In operation, the open collet fingers are placed over a threaded collar with said extension in engagement with a corresponding recess in the end of the bolt within the collar. The socket and mandrel are rotated in the collar unthreading direction. The latch mechanism latches the pin and collet together, preventing rotation of the collet. This causes the mandrel to thread into the collet and move downwardly forcing the fingers to grip onto the collar and bringing frictional contact between the mandrel and collet. This frictional contact tries to force the collet to rotate with the mandrel, to thus cause the latch to release and the collet to rotate with the mandrel. Continued rotation of the mandrel causes the collet fingers to further tighten on the collar until the collar unthreads from the bolt.