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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Quantifying the impact of precision errors on quantum approximate optimization algorithms

The quantum approximate optimization algorithm (QAOA) is a hybrid quantum-classical algorithm that seeks to achieve approximate solutions to optimization problems by iteratively alternating between intervals of controlled quantum evolution. Here, we examine the effect of analog precision errors on QAOA performance from the perspective of both algorithmic training and performance guarantees. Leveraging cumulant expansions, we recast the faulty QAOA as a control problem in which precision errors are expressed as multiplicative control noise and derive bounds on the performance of QAOA. We show using both analytical techniques and numerical simulations that fixed precision implementations of QAOA circuits are subject to an exponential degradation in performance dependent upon the number of optimal QAOA layers and magnitude of the precision error. Despite this significant reduction, we show that it is possible to mitigate precision errors in QAOA via digitization of the variational parameters at the cost of increasing circuit depth.

quantum algorithms↗
NASA NTRS1964

Stabilization and control systems.

Spacecraft attitude control and stabilization emphasizing control computers, switching logic, mission requirements and system design

SPACECRAFT STABILITY↗
NASA NTRS1970

Switching circuits with fast response and low power drain

New logic circuits have response times no longer than 10 nanoseconds and drain only milliwatts of power. The family includes AND and NAND gates and forms the basis of all logic functions. The basic circuits are used in various types of digital-data-processing systems.

Cancro, C. A.↗
NASA NTRS1971

Nonvolatile read/write memory element - A concept

Memory, with limited number of programming cycles, is achieved by using verticle, fusible links in series with oxide breakthrough elements. Memory elements are fabricated with integrated circuit technology and are ideal for low power digital computer application.

Cricchi, J. R.↗
NASA NTRS1977

Rate-of-change limiter for quantized signals

Analog circuit is employed to smooth change between levels of quantized voltage signal without adversely affecting its fidelity. Circuit is applicable to units requiring interface between digital and analog systems such as automated manufacturing systems or industrial robots.

Streuding, G. C.↗
NASA NTRS1977

Synthesis and implementation of state-trajectory control law for dc-to-dc converters

Mathematical representations of a state-plane switching boundary employed in a state-trajectory control law for dc-to-dc converters are derived. Two approaches to implementing the control law are discussed; one approach employs a digital processor and the other uses analog computational circuits. Performance characteristics of experimental voltage step-up dc-to-dc converters operating under the control of each of these implementations are presented.

Burns, W. W., III↗
NASA NTRS1977

Fast-response free-running dc-to-dc converter employing a state-trajectory control law

A recently proposed state-trajectory control law for a family of energy-storage dc-to-dc converters has been implemented for the voltage step-up configuration. Two methods of realization are discussed; one employs a digital processor and the other uses analog computational circuits. Performance characteristics of experimental voltage step-up converters operating under the control of each of these implementations are reported and compared to theoretical predictions and computer simulations.

Huffman, S. D.↗
NASA NTRS1980

Smoothing the output from a DAC

Circuit smooths stepped waveform from analog-to-digital converter without appreciable phase shift between stepped input signal and smoothed output signal and without any effect from stepping rate. Waveform produced is suitable for driving controls used in manufacturing processes, aerospace systems, and automobiles.

Wagner, C.↗
NASA NTRS1990

A novel demodulator/detector for digital and analog signals on LMR channels

The design, implementation, and performance of an all-digital demodulator/detector suitable for differentially encoded phase-shift keying (DPSK), continuous-phase frequency-shift keying (CPFSK), frequency-shift keying (FSK), and analog FM are discussed. In this demodulator/detector, two detectors, one noncoherent and another differentially coherent, operate simultaneously to provide data detection and automatic frequency control (AFC). Test results indicate that the system provides improved performance over the conventional analog quadrature detector for two-period raised-cosine (2RC) CPFSK modulation in additive white Gaussian noise (AWGN) and Rayleigh fading channels. Being all-digital, the demodulator/detector is well suited for integrated circuit implementation. In addition, the system performs as well as the analog quadrature detector for analog FM voice transmissions, thereby maintaining full compatibility with analog land mobile radio (LMR) transmissions.

Saulnier, Gary J.↗
NASA NTRS1994

Integration and test of high-speed transmitter electronics for free-space laser communications

The NASA Lewis Research Center in Cleveland, Ohio, has developed the electronics for a free-space, direct-detection laser communications system demonstration. Under the High-Speed Laser Integrated Terminal Electronics (Hi-LITE) Project, NASA Lewis has built a prototype full-duplex, dual-channel electronics transmitter and receiver operating at 325 megabit S per second (Mbps) per channel and using quaternary pulse-position modulation (QPPM). This paper describes the integration and testing of the transmitter portion for future application in free-space, direct-detection laser communications. A companion paper reviews the receiver portion of the prototype electronics. Minor modifications to the transmitter were made since the initial report on the entire system, and this paper addresses them. The digital electronics are implemented in gallium arsenide integrated circuits mounted on prototype boards. The fabrication and implementation issues related to these high-speed devices are discussed. The transmitter's test results are documented, and its functionality is verified by exercising all modes of operation. Various testing issues pertaining to high-speed circuits are addressed. A description of the transmitter electronics packaging concludes the paper.

Soni, Nitin J.↗
NASA NTRS1995

Artifacts Of Spectral Analysis Of Instrument Readings

Report presents experimental and theoretical study of some of artifacts introduced by processing outputs of two nominally identical low-frequency-reading instruments; high-sensitivity servo-accelerometers mounted together and operating, in conjunction with signal-conditioning circuits, as seismometers. Processing involved analog-to-digital conversion with anti-aliasing filtering, followed by digital processing including frequency weighting and computation of different measures of power spectral density (PSD).

Wise, James H.↗
NASA NTRS2006

Radiation Tolerant Intelligent Memory Stack (RTIMS)

The Radiation Tolerant Intelligent Memory Stack (RTIMS), suitable for both geostationary and low earth orbit missions, has been developed. The memory module is fully functional and undergoing environmental and radiation characterization. A self-contained flight-like module is expected to be completed in 2006. RTIMS provides reconfigurable circuitry and 2 gigabits of error corrected or 1 gigabit of triple redundant digital memory in a small package. RTIMS utilizes circuit stacking of heterogeneous components and radiation shielding technologies. A reprogrammable field programmable gate array (FPGA), six synchronous dynamic random access memories, linear regulator, and the radiation mitigation circuitries are stacked into a module of 42.7mm x 42.7mm x 13.00mm. Triple module redundancy, current limiting, configuration scrubbing, and single event function interrupt detection are employed to mitigate radiation effects. The mitigation techniques significantly simplify system design. RTIMS is well suited for deployment in real-time data processing, reconfigurable computing, and memory intensive applications.

Ng, Tak-kwong↗
NASA NTRS1997

Room and Low Temperature Performance of High-Speed Neural Network Circuits

We have described a challenging neural-network hardware implementation that would mate a 64x64-pixel infrared sensor directly on to a 3-dimensionally packaged set of neural processing chips with parallel input for high speed image processing. Non linearity effects and range compression are also discussed.

high-speed neural network circuits neural network ↗
NASA NTRS1994

Development of CMOS Active Pixel Image Sensors for Low Cost Commercial Applications

This paper describes ongoing research and development of CMOS active pixel image sensors for low cost commercial applications. A number of sensor designs have been fabricated and tested in both p-well and n-well technologies. Major elements in the development of the sensor include on-chip analog signal processing circuits for the reduction of fixed pattern noise, on-chip timing and control circuits and on-chip analog-to-digital conversion (ADC). Recent results and continuing efforts in these areas will be presented.

active pixel image sensors CMOS signal processing ↗
NASA NTRS2011

Continuous-Integration Laser Energy Lidar Monitor

This circuit design implements an integrator intended to allow digitization of the energy output of a pulsed laser, or the energy of a received pulse of laser light. It integrates the output of a detector upon which the laser light is incident. The integration is performed constantly, either by means of an active integrator, or by passive components.

Karsh, Jeremy↗
NASA NTRS2011

Radiation-Tolerant Intelligent Memory Stack - RTIMS

This innovation provides reconfigurable circuitry and 2-Gb of error-corrected or 1-Gb of triple-redundant digital memory in a small package. RTIMS uses circuit stacking of heterogeneous components and radiation shielding technologies. A reprogrammable field-programmable gate array (FPGA), six synchronous dynamic random access memories, linear regulator, and the radiation mitigation circuits are stacked into a module of 42.7 42.7 13 mm. Triple module redundancy, current limiting, configuration scrubbing, and single- event function interrupt detection are employed to mitigate radiation effects. The novel self-scrubbing and single event functional interrupt (SEFI) detection allows a relatively soft FPGA to become radiation tolerant without external scrubbing and monitoring hardware

Ng, Tak-kwong↗