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Gamma, X-ray, electron, or other radiation is used to shift threshold potentials of MOS devices on logic circuits. Before irradiation MOS gates to be shifted are biased positive and other gates are grounded to substrate. Threshold lasts 10 years. Thermal annealing brings circuit back to original configuration.
Logic controlled solid state circuit breakers and power transfer switches have been designed and built to demonstrate their use for 270 V dc power systems. This switchgear provides remote operation, automatic current level, and operates several orders of magnitude faster with much greater accuracy of response than conventional switchgear.
A feasibility study to design and demonstrate solid-state switchgear composed of circuit breakers and a power transfer switch is described. The switchgear operates on a nominal 270 Vdc circuit and controls power to a load up to 15 A. One circuit breaker may be interconnected to a second to form a power transfer switch. Breaker or switch on-off and transfer functions can be remotely controlled. Automatic overload trip-out is provided through an ultimate current trip and an I squared t trip for transient overcurrents lower than the ultimate current trip level. A number of reclosures with variable time delay between trip-out and reclosure are programmed and controlled by integrated analog and COSMOS logic circuits. A commutation circuit that creates minimal transient disturbances to either source or load was developed to interrupt current flow through the main SCR switching element.-
A feasibility study to design and demonstrate solid state switchgear in the form of circuit breakers and a power transfer switch is described. The switchgear operates on a nominal 270 V dc circuit and controls power to a load of up to 15 amperes. One circuit breaker may be interconnected to a second breaker to form a power transfer switch. On-off and transfer functions of the breakers or the transfer switch are remotely controlled. A number of reclosures with variable time delay between tripout and reclosure are programmed and controlled by integrated analog and COSMOS logic circuits. A unique commutation circuit, that generates only minimal transient disturbance to either source or load, was developed to interrupt current flow through the main SCR switching element. Laboratory tests demonstrated performance of the solid state circuit breakers over specified voltage and temperature ranges.
A study was conducted to define the logic associated with the control moment gyroscopes to maneuver and stabilize an orbiting spacecraft. The study objectives are as follows: (1) to define mission requirements and feasible attitudes for a shuttle-like vehicle that will meet mission objectives, (2) to determine the control moment gyroscope (CMG) and system configurations that will best meet overall mission requirements, (3) to define all of the software required to manage and control the selected CMG systems, and (4) to verify by computer simulation the adequacy of the selected CMG system and specified software package in meeting the overall mission requirements.
A study was conducted to validate the ground based simulators used for aircraft environment in ride-quality research. The logic to the approach for solving this problem is developed. The overall problem solution flow chart is presented. The factors which could influence the human response to the environment on board the aircraft are analyzed. The mathematical models used in the study are explained. The steps which were followed in conducting the validation tests are outlined.
The NASA Lewis Research Center is conducting a closed-Brayton-cycle power conversion system technology program in which a complete power system (engine) has been designed and demonstrated. This report discusses the design of automatic startup and shutdown logic circuits as a modification to the control system presently used in this demonstration engine. This modification was primarily intended to make starting the engine as simple and safe as possible and to allow the engine to be run unattended. In the modified configuration the engine is started by turning the control console power on and pushing the start button after preheating the gas loop. No other operator action is required to effect a complete startup. Shutdown, if one is required, is also effected by a simple stop button. The automatic startup and shutdown of the engine have been successfully and purposefully demonstrated more than 50 times at the Lewis Research Center during 10,000 hours of unattended operation. The net effect of this modification is an engine that can be safely started and stopped by relatively untrained personnel. The approach lends itself directly to remote unattended operation.
An interactive dialog with a computerized information collection was recorded and plotted in the form of a flow chart. The process permits one to identify the logical processes employed in considerable detail and is therefore suggested as a tool for measuring individual thought processes in a variety of situations. A sample of an actual test case is given.
A detailed description is presented of the computer programs in order to provide an understanding of the mathematical and geometrical relationships as implemented in the programs. The individual sbbroutines and their underlying mathematical relationships are described, and the required input data and the output provided by the program are explained. The relationship of the adaptive maneuvering logic program with the program to drive the differential maneuvering simulator is discussed.
Iterative building-block approach is used to minimize component count. Modular design has same logic structure for all bits.
Fail-sense circuit has majority-voted logic component which receives three error voltage signals that are sensed at single point by three error amplifiers. If transistor shorts, only one signal is required to operate; if transistor opens, two signals are required.
A parallel algorithm for counting the number of logic-l elements in a binary array or image developed during preliminary investigation of the Tse concept is described. The counting algorithm is implemented using a basic combinational structure. Modifications which improve the efficiency of the basic structure are also presented. A programmable Tse computer structure is proposed, along with a hardware control unit, Tse instruction set, and software program for execution of the counting algorithm. Finally, a comparison is made between the different structures in terms of their more important characteristics.
Low-power TTL circuit produces an output pulse whenever logic level at its input terminal changes. Circuit can also be used for doubling square-wave frequency.
Simple arrangement of four integrated circuits changes stream of binary data from non-return-to-zero (NRZ) coding to biphase logic coding. Selection of wiring and integrated circuits enables control and balancing of propagation delay without requiring excessive and expensive hardware.
Systematic method for representing multivariate finite Galois field functions can simplify synthesis of multivalued logic elements.
The distinctive feature of a tilt-rotor aircraft is that the pilot can change the rotor mast angles to go from a helicopter configuration for take-off and landing to an airplane configuration for high cruise speeds and vice-versa. An approach path for such an aircraft is proposed and the logic required to fly along this path in the presence of wind is determined. The main contribution of this work is an efficient and, to my knowledge, new method for generating the nominal state and control histories taking into account an estimate of the mean wind velocity and direction. The method requires the solution of algebraic (mostly linear) equations to generate a 'universal nominal', and feedforward and feedback gains. Then, in flight the additional state and control corrections due to deviation in descent rate, deceleration, and flight in a steady wind are obtained by multiplying simple precalculated functions of time by descent rate, deceleration or sine and cosine components of the mean wind vector. Simulations of approach flights for different wind conditions, assuming perfect state information in the feedback signal, indicated satisfactory performance.
Four inexpensive thermocouples monitor temperatures at key points. On command from logic circuitry, dampers open and close to direct airflow, and fan and auxiliary heater shut on or off. Controlling complex arranges heating system in any one of four operating configurations.
The algorithms and logic for use in the implementation of instrument landing system (ILS) localizer deviation signals for the generation of navigation and guidance information are presented. The navigation position estimates, based on range information from a randomly chosen distance measuring equipment (DME) and ILS localizer deviation information, are illustrated. The ILS volumetric coverage and DME geometric checks are described and their addition to area navigation systems with minimum software modification are discussed.