Showing papers by "General Dynamics published in 1992"

Lightweight solar concentrator cell array

Abstract: A self supporting solar concentrator cell array adapted for use in space applications that includes a plurality of cylindric parabolic reflective mirror surfaces, each of which focus recipient sunlight forwardly onto a focal line which is positioned approximately on the backside of an adjacent mirror surface on which is secured a solar element for converting the focussed sunlight into electricity. A front element extending upwardly from the leading edge of each mirror surface cooperates in providing an aperture through which the focussed sunlight passes and side elements close each cell element. The backside of each mirror is provided with a thermally emissive surface to provide mirror thermal control and allows the mirror to act as a thermal radiator fin for the solar cell elements. The mirror surface is provided with a highly reflective coating such as aluminum or silver to optimize reflectivity. The solar cell concentrator cell array is made by forming an uncured advanced organic composite part blank over a highly polished tool surface to impart the desired mirror surfaces. The solar concentrator cell array is cured, for example, by heated press means to form a unitary integral cell array that is entirely self supporting and provides structural stability while providing optimum electrical power output for minimum weight.

Cryptographic key management apparatus and method

Abstract: A method for establishing a secure communications link between first and second terminals includes a step of exchanging a first message. The first message contains information describing encryption devices and communications modes available within the terminals and user authentication information. The method also includes a step of selecting, in at least one terminal, a common key generation and ciphering algorithm. The method further includes steps of exchanging a second message for providing data to form traffic keys, exchanging a third message for synchronizing secure communications and initiating secure communication.

Plated compliant lead

Abstract: A curved lead (14) provides a mechanical and electrical connection between a board contact (21) on a circuit board (20) and a chip contact (16) associated with a circuit chip (18). The chip (18) can be mounted to the circuit board (20), to a chip carrier (12) or to a multiple-chip module (90). The curved lead (14) is substantially entirely plated with solder and is formed of a single piece of conductive material (56). The curved lead (14) has a first surface (58) for connection to the chip contact (16) and a second surface (60), generally parallel to the first surface (58), for connection to the board contact (21). The first and second surfaces (58, 60) are connected by at least one curved portion and are arranged to mount the circuit chip (18) to the circuit board (20) with the solder in a compliant, generally parallel arrangement substantially free of stress.

Continuous processing/in-situ curing of incrementally applied resin matrix composite materials

Abstract: A method for continuous processing/in-situ consolidation and curing of thermoset resin impregnated fiber tow into a composite product having minimal porosity and being relatively void free. The method provides for preconditioning a fiber, impregnating a continuous fiber tow with a low viscosity thermoset resin to complete saturation and then simultaneously outgassing and advancing the resin impregnated tow. The preconditioned tow is then applied to a substrate such as a heated rotating mandrel in a filament winding procedure where heat is applied to the nip of the touch-down of the tow to the mandrel with the simultaneous application of pressure for initial consolidation of the tow upon the substrate. Additional pressure and heat are applied to the tow as the mandrel is rotated to provide for advancing the stage of the resin and further consolidation of the material. The combination of the pressures and heat applied to the outer surface of the material on the mandrel produce a unitary composite product without delaminations. Preferably, the serial continuous process is monitored using an appropriate inspection method focused on the material on the mandrel to permit in-line optimization of the product as it is being consolidated and cured on the mandrel. The method is equally applicable to various automated resin matrix composite material deposition arrangements such as filament winding, tape laying, and pultrusion.

Operational versus definitional: a perspective on programming paradigms

Abstract: Various paradigms that support high-level programming are discussed independently of supporting languages. The paradigms are grouped according to their approach to problem solving. The operational approach describes step-by-step how to construct a solution. The demonstrational approach is a variation on it that illustrates the solution operationally for specific examples and lets the system generalize these example solutions for other cases. The definitional approach is different. It states properties about the solution to constrain it without describing how to compute it. These three approaches are viewed on a continuum from operational to definitional. A pure language solution to the problem of sorting a list into some linear order is presented for each paradigm. >

Algorithm independent cryptographic key management

Abstract: An apparatus for secure communications contains a controller for automatically selecting one of several data ciphering devices utilizing one of a plurality of ciphering algorithms common to transmitting and receiving terminals. A transmitter for transmitting encrypted data, and a receiver for receiving encrypted data are coupled to the plurality of ciphering devices. The controller automatically determines which of the ciphering devices to employ for any given secure communication. The method for establishing a secure communications link includes the steps of exchanging a first message for determining a common key generation and ciphering method and comparing a further shared message for validation of communications terminal security. Additionally, the steps of trading a still further message for providing data to form traffic keys to initialize key generators, interchanging an additional message for synchronizing and verifying synchronization of secure communications between secure communications terminals, and initiating secure communication are used.

Method for killing barnacle larvae in water

Abstract: Biofouling of underwater surfaces by marine organisms is prevented by irradiating the water with ultraviolet light and adjusting the intensity of the ultraviolet light so as to kill barnacle larvae to prevent their attachment to the underwater surface. The water is passed through a biocidal chamber having a source of ultraviolet light at an intensity of at least 4000 μwatts/cm 2 and at a rate to provide a residence time of at least one minute on the biocidal chamber.

Reliability measurement: from theory to practice

Abstract: The gap between theory and practice of reliability measurement in software design is discussed, and key issues that underlie reliability measurement's evolution from theory to practice are presented. A panel discussion in which reliability measurement's salient issues, basic concepts, and underlying theory are outlined is included. Reliability measurement's role in the development life cycle is also discussed. >

Apparatus for multipath DSSS communications

Abstract: Circuit for recovery of a plurality of multipath direct sequence spread spectrum signal components received over a time span, wherein the multipath signal components are components of a signal generated from digital data comprised of data bits at a data bit rate modulated by a pseudo-noise code, consisting of a sequence of chips having a chip rate greater than the data bit rate, wherein the sequence of chips is a code repetition period equal or greater than the received time span of the multipath signal components. A plurality of correlators is provided. Each correlator has a first input for coupling to the multipath signal components, a second input, and an output. A pseudo-noise code generator generates a duplicate of the pseudo-noise code. A time delayer is coupled between the second inputs of a mulitiplicity of the correlators and the pseudo-noise code generator for delaying the duplicate of the pseudo-noise code by a multiple of a time delay equal to the time of a chip duration or less. A signal combiner is coupled to the plurality of phase correcting devices.

Ambiguities in evaluating performance of multiple target tracking algorithms

Abstract: Evaluating performance of tracking algorithms is straightforward for a simulation with a single target and one computed track. Performance evaluation with multiple targets, on the other hand, is complex due to ambiguities that create confusion about which target goes with a track. The ambiguities are caused by misassociations or unresolved closely spaced objects. Various considerations in choosing a methodology for performance evaluation to handle these ambiguities are discussed. An approach to assigning tracks to targets is described that takes these considerations into account.

Memory tagging for object reuse protection

Abstract: A method and apparatus for memory tagging for object reuse protection which includes a central processing unit (CPU), a memory for storing a data word object and a corresponding tag identifying a first process with a first identification (ID) The memory means is coupled to the CPU A subject ID register for storing a current process ID for a current process is coupled to the CPU and the memory Tag checking apparatus for comparing the current process ID to the first ID is coupled to the CPU, to the subject ID register, and to the memory Control logic is coupled to the CPU, to the memory, and to the tag checking apparatus The control logic is for denying access to the data word object by the current process if the current process ID does not match the first ID

Forebody vortex flow control on the F-16C using tangential slot and jet nozzle blowing

Abstract: The present experimental investigation of the effects of tangential slot and nozzle forebody blowing on the aerodynamic and stability characteristics of the F-16C configuration, for up-to-55 deg alpha and up-to-20 deg sideslip, was conducted on a 1/15th-scale model at freestream Mach = 0.4 and Re of 2.5 million/ft, for one tangential slot-nozzle location and two chordwise jet nozzle locations. Both the slot and the jet nozzles generated large yawing moments at very low blowing rates, over a wide range of alpha and sideslip angles. The centers of pressure of the side forces which generated the yawing moments due to slot and nozzle blowing were located in the region of the leading-edge extensions (LEXs); the moments may accordingly be due to the manipulation of the combined forebody and LEX flowfields.

Automatic noise characterization for optimally enabling a receiver

Abstract: A multi-channel receiver automatically determines the noise floor of each channel and resets the channel threshold based thereon while avoiding undesirable bias from weak non-noise signals. The power probability of uncharacterized input signals (non-noise content unknown) is computed and normalized to have a known probability that the power exceeds a first threshold. A second probability of exceeding a second threshold is determined and compared to a predetermined reference probability for a noise-only signal at the same threshold. If the computed second probability is not higher than the reference probability, then the uncharacterized signal is a noise only signal whose average is the noise floor for the channel. The threshold detection level is then set a predetermined amount above the noise floor. The process is automatic and compensates for receiver aging and ambient noise fluctuations with time and from channel to channel and for other changes.

Plasma based soldering by indirect heating

Abstract: A method of soldering without the use of flux, wherein a plurality of solder bumps are deposited on a first surface and a plurality of solder pad locations are prepared on a second surface. The first and second surfaces are placed immediately adjacent to one another, placing each the plurality of solder bumps in the proximity of a corresponding solder pad location on the second surface. The first surface, the second surface and the solder are placed in a chamber which is evacuated to a low pressure. A plasma is excited within the chamber which heats the first and the second surfaces, thereby heating the plurality of solder bumps and the plurality of solder pad locations by heat conduction and reflowing the plurality of solder bumps on the first surface and on the plurality of solder pad locations on the second surface to form a plurality of solder bonds therebetween.

Apparatus and method of using fiber-optic light guide for heating enclosed test articles

Abstract: An apparatus and method for providing a specified amount of heat on a test specimen, a portion of a specimen, or multiple specimens, under space-like conditions. This system includes a vacuum chamber in which one or more test specimens are placed. This chamber is evacuated to the necessary vacuum. One or more external sources of high intensity light is used for providing the necessary temperature. One or more reflectors are used for concentrating the high intensity light. A fiber optic light guide is used for receiving concentrated light from the reflector. A port in the vacuum chamber wall is used so that the second end of the light guide can extend into the chamber so that light exiting the second end impinges on a selected area of the test specimen. A positioning apparatus is used for locating the second end of the light guide within the housing adjacent to vary the test specimen area subjected to the light. One or more temperature sensors is used on the test specimens for providing feedback to the temperature controlling system for controlling the amount of light input to the guide to achieve the desired temperature.

Method of fabricating conductive structures on substrates

Abstract: The present invention is an integrated heat sink module and a method of fabricating conductive structures on a substrate. The method of the present invention includes cleaning a substrate material to remove any impurities present on the substrate surface. The method further includes placing a protective layer resilient to chemicals used in conductive structure formation, on a first surface. The first surface is opposite a second surface on which conductive structures are formed. The method includes forming conductive structures on the second surface of the substrate. The protective layer is then removed from the first surface of the substrate.

Object reuse protection with error correction

Abstract: A method and apparatus for providing error detection, correction and prevention of unauthorized access to data using memory tags. The method and apparatus includes computing an original error detection/correction code associated with a data word. The original error detection/correction code, using a CPU and a subject identification register, is copied to a tag associated with the data word when an original subject writes the data word into a memory. A single-error-correction/double-error detection (SEC/DED) device applies a first bias to the tag to create a first-biased error detection/correction code when the memory is assigned to a first subject. The SEC/DED device applies a second bias to create a twice-biased error detection/correction code when a second subject attempts to access the data word. Access to the data word is denied if the twice-biased error detection/correction code comprises an uncorrectable error.

Tool to assist in the removal of rivets

Abstract: A tool to be used in cooperation with a rotatable drill having a shoulder portion and a shank portion to remove set rivets securing parts together. The tool includes a hollow compressible means which surrounds the drill. The compressible means is provided at one end with a relieved surface having a contour that mates with the head of the rivet and with a central bore through which passes the drill. Spacers may be provided between the shoulder portion of the drill and the tool as well as may be friction reducing. The drill is moved toward the head of the set rivet through the tool and into cutting engagement with the rivet head to cut away the central portion of the rivet head without inadvertent disengagement. The tool may then be removed from the drill to permit the rivet to be knocked out of the parts or the drill may then be used to drill out the remainder of the stem of the rivet.

Method and apparatus using photoresistive materials as switchable EMI barriers and shielding

Abstract: A method and apparatus for providing a switchable electromagnetic interference (EMI) barrier. The method protects an object against electromagnetic radiation, through the steps of: providing an object to be protected from electromagnetic radiation; placing a barrier sheet adjacent to the object, the sheet being opaque to radiation when exposed to light; directing the light against the sheet when a barrier to the radiation is desired; and extinguishing the light when passage of the radiation through the sheet is desired. One embodiment is a switchable electromagnetic radiation barrier system that includes a photoresistive sheet interposed between a source of electromagnetic radiation and an object to be protected from the radiation. This sheet is opaque to the radiation when exposed to light of a selected visible intensity range. A light source adjacent to this sheet directs the light against the sheet. A second embodiment is an apparatus for protecting an EMI-sensitive device in an air vehicle from external electromagnetic radiation (EMR). The apparatus includes: a cavity in an air vehicle; an EMI-sensitive device in the cavity; and a barrier window covering the cavity. The window includes a support sheet having a layer of photoresistive material. This material transmits EMR when exposed to light and does not transmit EMR when unlighted. A light source is provided to selectively illuminate the layer. Another embodiment is an antenna element of layered sandwich construction, including a polyimide film layer. Switchable means are used in the embodiments to turn the light source off and on.

Method and apparatus for volume switched gain control

Abstract: An apparatus comprises a first and a second input and a processor coupled to the inputs. The processor estimates peak and minimum levels of each of the first and second input signals. A first signal regulator is coupled to the first input and to a first output for delivering a first output signal from the first signals. A second signal regulator is coupled to the second input and to a second output for delivering a second output signal from the second audio signals. A gain adjustment device is coupled to the processor and the first and second signal regulators. The gain adjustment device provides control signals to the first and second signal regulators to adjust an output signal level of the first output signal in response to minimum and peak levels of the first and second input signals. The output signal level is continuously variable over a range.

Application of Advanced Multidisciplinary Analysis and Optimization Methods to Vehicle Design Synthesis

Abstract: Advanced multidisciplinary analysis and optimization methods; namely, system sensitivity analysis and nonhierarchical system decomposition, are applied to reduce the cost and improve the visibility of an automated vehicle design synthesis process. This process is inherently complex due to the large number of functional disciplines and associated interdisciplinary couplings. Recent developments in system sensitivity analysis as applied to complex nonhierarchic multidisciplinary design optimization problems enable the decomposition of these complex interactions into subprocesses that can be evaluated in parallel. The application of these techniques may result in very significant computational and calendar time savings, furthermore they may result in significant cost, accuracy, and visibility benefits for the entire design synthesis process.

Multiple radar interference suppressor

Abstract: A multiple radar interference suppressor for use in a missile scoring system. The multiple radar interference suppressor phase locks the pulse repetition frequency of each drone (unmanned) aircraft to one other drone of the plurality of aircrafts. The phase of the pulse repetition frequency of each of the transmitting radars of the drones is slightly offset from one another. As a result, mutual interference among the drones transmitting radar signals and receiving radar signals of other drones is overcome. Lastly, the transmitted signals and received signals are encoded so that unwanted reflections and scattering from a target may be substantially eliminated or suppressed.

Cleaning formulation and method that alleviates current problems

Abstract: Disclosed are formulations for producing chemical solvent admixtures that can be employed to clean a surface for further work or can be applied to cloths for the cleaning operation. The disclosed formulations and methods of disposing the formulations alleviate problems due to solvent evaporation into the atmosphere which cause many legal and environmental problems. The figure exemplifies a preferred method of disposing of cloths which have been contacted with the disclosed formulations and applied to a surface in a cleaning operation.

Method of leak detection using a releasable surface film

Abstract: A method of detecting leaks through a surface using a flexible film releasably bonded to the surface Surfaces of pressurized fluid holding structures having a large number of surface penetrations, such as rivets, tend to have problems with leaks Leaks at these penetrations are detected by forming a continuous film, typically a polymer film over the surface of a closed structure, pressurizing the structure with a suitable fluid and detecting leaks by the bubbles that form in the film Generally, the bubbles ar reaily apparent due to tint changes in the film areas no longer in contact with the structure surface Bubbles are also easily detected by feel The film is removed around bubbles and the leaking penetration is repaired Those areas can again be coated with the film and the structure repressurized to detect any remaining leaks This test can be repeated until all leaks are eliminated The film is then stripped from the surface and the structure is ready for cleaning use or further processing

Effects of speckle on the range precision of a scanning lidar.

Abstract: The dynamic speckle generated by a scanning lidar is a major contributor to the range precision for long transmitter pulses, such as those for a linear frequency-modulation-chirp waveform. The linear portion of the speckle-phase variations is automatically compensated, and the range precision is significantly improved, when an upchirp and downchirp pair is transmitted simultaneously, combined with a proper demodulation process. This concept was verified through a laboratory demonstration. The effect of speckle-amplitude variations on the compressed-pulse waveform is also investigated.

Methods and arrangements tailoring aerodynamic forces afforded by a payload to reduce flight loads and to assist flight control for the coupled system

Abstract: An arrangement for controlling the flight of a launch vehicle and a coupled payload, such a spaceplane, from launch to the separation of the payload from the vehicle. The launch vehicle is provided with controllable gimballed rocket engines and optionally with aerodynamic control surfaces, that are controlled by flight control systems. The payload having controlled flight surfaces has control systems that cooperate with those flight control systems carried by the launch vehicle to jointly control the coupled launch vehicle and coupled payload during coupled flight. The cooperating flight control systems provide open and closed loop control systems that react to winds measured prior to launch and atmospheric disturbances as indicated by on-board sensors during flight. The payload is mounted on the launch vehicle at a cant angle relative to the longitudinal axis of the launch vehicle to optimize its lift to the coupled launch vehicle and payload. Roll steering is also used to minimize the exposure of the vehicle's most critical plane to atmosphere disturbances and/or to maximize available control authority, in addition to pitch and yaw steering.

Global Least Squares Matching

Abstract: Global Least Squares Matching (GLSM) is an advanced image matching technology that automates the image correlation process for applications such as very dense elevation data extraction, f e m e extraction, change detection, and automated mapping. GLSM was invented in 1976-77 by Dr. Urho Rauhala as an application of his efficient array algebra solution techniques to support stereo mensuration rates on the order of hundreds of posts per second on a general purpose 1 MIPS computer. This paper summarizes the GLSM technology and discusses some experimental results. All cases demonstrate GLSMs ability to produce dense image mensurations with very high reliability, accuracy and resolution. Other GLSM applications include Large Area Digital Image Maps, GIs database maintenance, automated planetary mapping, and vehicle navigation.