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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Lidar method of measurement of atmospheric extinction and ozone profiles

A description of a method of measurement of atmospheric extinction and of ozone profiles by use of the backscatter signal from a monostatic lidar is given. The central feature of the procedure involves a measurement of the ratio of the Raman backscatter returns of both the oxygen and nitrogen atmospheric content. Because the ratio of the number density of both species is known to high accuracy, the measurement itself becomes a measure of the ratio of two transmissions to altitude along with a ratio of the two system constants. The calibration measurement for determining the value of the ratio of the two system constants or electro-optical conversion constants is accomplished by a lidar measurement of identical atmospheric targets while at the same time interchanging the two optical filters in the two optical channels of the receiver. More details of the procedure are discussed. Factoring this calibrated value into the measured O2/N2 profile ratio provides a measured value of the ratio of the two transmissions. Or equivalently, it provides a measurement of the difference of the two extinction coefficients at the O2 and N2 Raman wavelengths as a function of the height.

Cooney, J. A.↗
NASA NTRS2003

Apparatus and Method for Measuring Strain in Optical Fibers using Rayleigh Scatter

An apparatus and method for measuring strain in an optical fiber using the spectral shift of Rayleigh scattered light. The interference pattern produced by an air gap reflector and backscattered radiation is measured. Using Fourier Transforms, the spectrum of any section of fiber can be extracted. Cross correlation with an unstrained measurement produces a correlation peak. The location of the correlation peak indicates the strain level in the selected portion of optical fiber.

Froggatt, Mark E.↗
DOE OSTI2022

TDCOSMO. IX. Systematic comparison between lens modelling software programs: time delay prediction for WGD 2038-4008

The importance of alternative methods for measuring the Hubble constant, such as time-delay cosmography, is highlighted by the recent Hubble tension. It is paramount to thoroughly investigate and rule out systematic biases in all measurement methods before we can accept new physics as the source of this tension. In this study, we perform a check for systematic biases in the lens modelling procedure of time-delay cosmography by comparing independent and blind time-delay predictions of the system WGD 2038-4008 from two teams using two different software programs: GLEE and LENSTRONOMY. The predicted time delays from the two teams incorporate the stellar kinematics of the deflector and the external convergence from line-of-sight structures. The un-blinded time-delay predictions from the two teams agree within 1.2σ, implying that once the time delay is measured the inferred Hubble constant will also be mutually consistent. However, there is a ~4σ discrepancy between the power-law model slope and external shear, which is a significant discrepancy at the level of lens models before the stellar kinematics and the external convergence are incorporated. We identify the difference in the reconstructed point spread function (PSF) to be the source of this discrepancy. When the same reconstructed PSF was used by both teams, we achieved excellent agreement, within ~0.6σ<, indicating that potential systematics stemming from source reconstruction algorithms and investigator choices are well under control. We recommend that future studies supersample the PSF as needed and marginalize over multiple algorithms or realizations for the PSF reconstruction to mitigate the systematics associated with the PSF. A future study will measure the time delays of the system WGD 2038-4008 and infer the Hubble constant based on our mass models.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Benchmark Analysis for the Optical Dilatometry Method Using Silicon Carbide Temperature Monitors

The main objective of this project was to conduct a benchmark analysis for the optical dilatometry method by using NSUF’s SiC temperature monitors: two (2) SiC temperature monitors provided by NSUF’s BSU-8242 experiment and two (2) SiC temperature monitors provided by NSUF’s GE-Hitachi experiment. Per the BSU-8242 experiment, KGT-3597 and KGT-3591 had a design temperature of 400°C and an exposure of 3 dpa. Per the GE-Hitachi experiment, KGT-3341 and KGT-3336 had a design temperature of 290°C +/- 50°C and an exposure of 0.5–1 dpa. The KGT-3336 SiC monitor was split into two pieces during the decontamination process, making the dilatometry method the only way to analyze both those pieces. The BSU-8242 monitors revealed peak irradiation temperatures under the design temperature, and the GE-Hitachi monitors revealed peak irradiation temperatures within the design temperature range. The optical dilatometry method measured the peak irradiation temperature of BSU-8242 KGT-3597 to be 330°C, while the resistivity method measured the peak irradiation temperature of BSU-8242 KGT-3591 to be 320°C +/- 20°C. The optical dilatometry method measured the peak irradiation temperatures of the pieces of GE-Hitachi KGT-3336 to be 260°C (for the larger piece) and 220°C (for the smaller piece), while the resistivity method measured the peak irradiation temperature of GE-Hitachi KGT-3341 to be 300°C, with an accuracy range of -50°C to +20°C. Both methods of SiC temperature monitor analysis produced very similar peak irradiation temperatures for each pair of SiC passive monitors from the two experiments, BSU-8242 and GE-Hitachi. The results show dilatometry method to be a reliable and less time-intensive process for determining irradiation temperatures from passive SiC thermometry.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Secure boot, trusted boot and remote attestation for ARM TrustZone-based IoT Nodes

With the extensive application of IoT techniques, IoT devices have become ubiquitous in daily lives. Meanwhile, attacks against IoT devices have emerged to compromise IoT devices by tampering with system pre-installed programs or injecting new malware. To mitigate these attacks, integrity enforcement of IoT systems has been proposed. The integrity of an IoT device system includes load-time integrity and runtime integrity. In this paper, we design an IoT system based on ARM TrustZone to enforce the system integrity. First, we establish the root of trust and propose a hybrid booting approach consisting of both secure boot and trusted boot to enforce the system load-time integrity. Second, we investigate a paging-based process integrity measurement method to measure the NW processes and conduct remote attestation based on the measurement results ensuring the NW runtime process integrity. We implement an IoT prototype system on a NXP i.MX6Q SABRE SD development board to assess its feasibility. Finally, real-world experiment results demonstrate that our prototype introduces negligible performance overhead to the original system.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1984

Power system applications of fiber optics

Power system applications of optical systems, primarily using fiber optics, are reviewed. The first section reviews fibers as components of communication systems. The second section deals with fiber sensors for power systems, reviewing the many ways light sources and fibers can be combined to make measurements. Methods of measuring electric field gradient are discussed. Optical data processing is the subject of the third section, which begins by reviewing some widely different examples and concludes by outlining some potential applications in power systems: fault location in transformers, optical switching for light fired thyristors and fault detection based on the inherent symmetry of most power apparatus. The fourth and final section is concerned with using optical fibers to transmit power to electric equipment in a high voltage situation, potentially replacing expensive high voltage low power transformers. JPL has designed small photodiodes specifically for this purpose, and fabricated and tested several samples. This work is described.

Kirkham, H.↗
NASA NTRS1934

A Comparison of Several Methods of Measuring Ignition Lag in a Compression-ignition Engine

The ignition lag of a fuel oil in the combustion chamber of a high speed compression-ignition engine was measured by three different methods. The start of injection of the fuel as observed with a Stoborama was taken as the start of the period of ignition lag in all cases. The end of the period of ignition lag was determined by observation of the appearance of incandescence in the combustion chamber, by inspection of a pressure-time card for evidence of pressure rise, and by analysis of the indicator card for evidence of the combustion of a small but definite quantity of fuel. A comparison of the values for ignition lags obtained by these three methods indicates that the appearance of incandescence is later than other evidences of the start of combustion, that visual inspection of a pressure-time diagram gives consistent and usable values with a minimum requirement of time and/or apparatus, and that analysis of the indicator card is not worth while for ignition lag alone.

Spanogle, J A↗
NASA NTRS2015

A Comparison of Three Methods for Measuring Distortion in Optical Windows

It's important that imagery seen through large-area windows, such as those used on space vehicles, not be substantially distorted. Many approaches are described in the literature for measuring the distortion of an optical window, but most suffer from either poor resolution or processing difficulties. In this paper a new definition of distortion is presented, allowing accurate measurement using an optical interferometer. This new definition is shown to be equivalent to the definitions provided by the military and the standards organizations. In order to determine the advantages and disadvantages of this new approach, the distortion of an acrylic window is measured using three different methods: image comparison, moiré interferometry, and phase-shifting interferometry.

Interferometry↗
DOE OSTI2026

Segmentation method comparison for residual fiber length measurement across tiled microscopy images

Fiber length distribution (FLD), in part, governs mechanical properties in discontinuous fiber composites, yet manual measurement methods limit the high-throughput characterization needed for materials design optimization. This study compares deep learning segmentation approaches for automated FLD measurement in large-field microscopy, evaluating how method choice affects the microstructural descriptors used in structure-property-processing relationships. A critical challenge is that high-resolution microscopy images (10,000×10,000 pixels) must be tiled for deep learning analysis, fragmenting fibers at boundaries. We demonstrate that segmentation method proves crucial for measurement accuracy. For example, instance segmentation with Slicing Aided Hyper Inference (SAHI) preserves individual fiber integrity across tiles while semantic segmentation prioritizes speed. Comparing against manual measurement of extracted carbon fibers, YOLOv11-SAHI matched manual ground truth (238 μm weighted mean) with 40x speedup (4.5 vs 167 minutes per image). U-Net provides rapid quantification although it is at the cost of reduced accuracy due only reliably measuring stand-alone fibers. Our comparative analysis reveals that instance segmentation with SAHI better preserves length measurements while semantic segmentation prioritizes speed, providing empirical guidance for method selection. The characterization provides essential inputs for mechanical property prediction models and inverse design workflows, accelerating composite materials development cycles.

Additive manufacturing↗
NASA NTRS1977

An analysis of the Wheeler method for measuring the radiating efficiency of antennas

A model problem is formulated to evaluate the limitations imposed by the assumptions in the Wheeler or cap method for measuring the radiating efficiency of antennas. The antenna in the model is a circular loop and the radiation shield is a spherical metal shell. Calculated values of the actual efficiency of the antenna and the efficiency that would be measured using the Wheeler method are compared to determine the accuracy of the method and set guidelines for its application.

Smith, G. S.↗
NASA NTRS1981

Investigation of Flight Test Methods for measuring the performance of general aviation aircraft

A theoretical and experimental investigation of methods for measuring the performance of general aviation airplanes was conducted using relatively simple instrumentation currently available and data extraction techniques established from efforts in other disciplines. The possibilities of improving flight test data by use of improved modern instrumentation and digital data recording and data analysis were considered.

Bull, G.↗
NASA NTRS1972

Methods of measurement for semiconductor materials, process control, and devices

Activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices are described. Topics investigated include: measurements of transistor delay time; application of the infrared response technique to the study of radiation-damaged, lithium-drifted silicon detectors; and identification of a condition that minimizes wire flexure and reduces the failure rate of wire bonds in transistors and integrated circuits under slow thermal cycling conditions. Supplementary data concerning staff, standards committee activities, technical services, and publications are included as appendixes.

Bullis, W. M.↗
NASA NTRS1972

Methods of measurement for semiconductor materials, process control, and devices

Activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices are described. Accomplishments include the determination of the reasons for differences in measurements of transistor delay time, identification of an energy level model for gold-doped silicon, and the finding of evidence that it does not appear to be necessary for an ultrasonic bonding tool to grip the wire and move it across the substrate metallization to make the bond. Work is continuing on measurement of resistivity of semiconductor crystals; study of gold-doped silicon; development of the infrared response technique; evaluation of wire bonds and die attachment; measurement of thermal properties of semiconductor devices, delay time, and related carrier transport properties in junction devices, and noise properties of microwave diodes; and characterization of silicon nuclear radiation detectors.

Bullis, W. M.↗
NASA NTRS1993

Simple in-line method to measure the dispersion of an optical system

We describe a simple in-line method to measure the dispersion of an optical system. The light beam passing through the optical system interferes with a reference beam in a spectrometer, and the resulting spectrum yields the quadratic and cubic dispersion terms of the system. We demonstrate this technique on an optical system made of grating pairs.

Yao, X. S.↗