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At least 73 records · Page 4

Spectral-Content Readout Of Stress-Induced Birefringence

Spectrum of transmitted light indicates stress in sensor or specimen. Photoelastic apparatus demonstrates feasibility of analysis of spectrum of transmitted light to quantify birefringence in transparent specimen. By augmenting conventional photoelastic analysis with spectral sensors and automating it with computer control and processing of data, technique made more versatile and useful. Potential uses include measurement of stresses in optical fibers and transparent materials in general.

Redner, Alex S.↗

Flight data acquisition methodology for validation of passive ranging algorithms for obstacle avoidance

The automation of low-altitude rotorcraft flight depends on the ability to detect, locate, and navigate around obstacles lying in the rotorcraft's intended flightpath. Computer vision techniques provide a passive method of obstacle detection and range estimation, for obstacle avoidance. Several algorithms based on computer vision methods have been developed for this purpose using laboratory data; however, further development and validation of candidate algorithms require data collected from rotorcraft flight. A data base containing low-altitude imagery augmented with the rotorcraft and sensor parameters required for passive range estimation is not readily available. Here, the emphasis is on the methodology used to develop such a data base from flight-test data consisting of imagery, rotorcraft and sensor parameters, and ground-truth range measurements. As part of the data preparation, a technique for obtaining the sensor calibration parameters is described. The data base will enable the further development of algorithms for computer vision-based obstacle detection and passive range estimation, as well as provide a benchmark for verification of range estimates against ground-truth measurements.

Smith, Phillip N.↗

Flight data acquisition methodology for validation of passive ranging algorithms for obstacle avoidance

An account is given of the methodology used to develop a data base containing low altitude imagery, augmented with the rotorcraft and sensor parameters required for passive-range estimation. The bata base is predicated on flight test data encompassing imagery, rotorcraft and sensor parameters, and ground truth range measurements. Data preparation was conducted by means of a novel technique for obtaining the sensor-calibration parameters. The data-base thus obtained will facilitate further development of computer vision-based obstacle-detection and passive range-estimation algorithms, as well as furnish a benchmark for verification of range estimates against ground-truth estimates.

Smith, Phillip N.↗

Visual Image Sensor Organ Replacement

This innovation is a system that augments human vision through a technique called "Sensing Super-position" using a Visual Instrument Sensory Organ Replacement (VISOR) device. The VISOR device translates visual and other sensors (i.e., thermal) into sounds to enable very difficult sensing tasks. Three-dimensional spatial brightness and multi-spectral maps of a sensed image are processed using real-time image processing techniques (e.g. histogram normalization) and transformed into a two-dimensional map of an audio signal as a function of frequency and time. Because the human hearing system is capable of learning to process and interpret extremely complicated and rapidly changing auditory patterns, the translation of images into sounds reduces the risk of accidentally filtering out important clues. The VISOR device was developed to augment the current state-of-the-art head-mounted (helmet) display systems. It provides the ability to sense beyond the human visible light range, to increase human sensing resolution, to use wider angle visual perception, and to improve the ability to sense distances. It also allows compensation for movement by the human or changes in the scene being viewed.

Maluf, David A.↗

Generating Land Surface Reflectance for the New Generation of Geostationary Satellite Sensors with the MAIAC Algorithm

The latest generation of geostationary satellite sensors, including the GOES-16/ABI and the Himawari 8/AHI, provide exciting capability to monitor land surface at very high temporal resolutions (5-15 minute intervals) and with spatial and spectral characteristics that mimic the Earth Observing System flagship MODIS. However, geostationary data feature changing sun angles at constant view geometry, which is almost reciprocal to sun-synchronous observations. Such a challenge needs to be carefully addressed before one can exploit the full potential of the new sources of data. Here we take on this challenge with Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm, recently developed for accurate and globally robust applications like the MODIS Collection 6 re-processing. MAIAC first grids the top-of- atmosphere measurements to a fixed grid so that the spectral and physical signatures of each grid cell are stacked (“remembered”) over time and used to dramatically improve cloud/shadow/snow detection, which is by far the dominant error source in the remote sensing. It also exploits the changing sun-view geometry of the geostationary sensor to characterize surface BRDF with augmented angular resolution for accurate aerosol retrievals and atmospheric correction. The high temporal resolutions of the geostationary data indeed make the BRDF retrieval much simpler and more robust as compared with sun-synchronous sensors such as MODIS. As a prototype test for the geostationary-data processing pipeline on NASA Earth Exchange (GEONEX), we apply MAIAC to process 18 months of data from Himawari 8/AHI over Australia. We generate a suite of test results, including the input TOA reflectance and the output cloud mask, aerosol optical depth (AOD), and the atmospherically-corrected surface reflectance for a variety of geographic locations, terrain, and land cover types. Comparison with MODIS data indicates a general agreement between the retrieved surface reflectance products. Furthermore, the geostationary results satisfactorily capture the movement of clouds and variations in atmospheric dust/aerosol concentrations, suggesting that high quality land surface and vegetation datasets from the advanced geostationary sensors can help complement and improve the corresponding EOS products.

geostationary satellite sensors↗

Analytical sensor redundancy assessment

The rationale and mechanization of sensor fault tolerance based on analytical redundancy principles are described. The concept involves the substitution of software procedures, such as an observer algorithm, to supplant additional hardware components. The observer synthesizes values of sensor states in lieu of their direct measurement. Such information can then be used, for example, to determine which of two disagreeing sensors is more correct, thus enhancing sensor fault survivability. Here a stability augmentation system is used as an example application, with required modifications being made to a quadruplex digital flight control system. The impact on software structure and the resultant revalidation effort are illustrated as well. Also, the use of an observer algorithm for wind gust filtering of the angle-of-attack sensor signal is presented.

Mulcare, D. B.↗

Sensor Data Analytics and Data Quality Assessment Software

The proposed framework derives a set of quality metrics to provide critical insights into and tracking of grid operations, sensor performance, sensor longevity, and event statistics. Power grid engineers can utilize this information to identify problems with existing sensor locations and problematic power grid assets including generators, transmission lines, load centers, and substations. This information can also be used to identify unexpected/abnormal behavior of power grid components, improve power grid observability, and operational monitoring, and thus enhance real-time decision-making support system. Power grid planners can utilize this information to augment existing sensing architecture with new sensors and improve the observability of the network.

Mahapatra, Kaveri↗

Human grasp assist device and method of use

A grasp assist device includes a glove portion having phalange rings, contact sensors for measuring a grasping force applied by an operator wearing the glove portion, and a tendon drive system (TDS). The device has flexible tendons connected to the phalange rings for moving the rings in response to feedback signals from the sensors. The TDS is connected to each of the tendons, and applies an augmenting tensile force thereto via a microcontroller adapted for determining the augmenting tensile force as a function of the grasping force. A method of augmenting a grasping force of an operator includes measuring the grasping force using the sensors, encoding the grasping force as the feedback signals, and calculating the augmenting tensile force as a function of the feedback signals using the microcontroller. The method includes energizing at least one actuator of a tendon drive system (TDS) to thereby apply the augmenting tensile force.

Linn, Douglas Martin↗

Improvements to the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) Calibration System

As a continuing effort to increase the calibration accuracy of the AVIRIS data a number of recent improvements have been implemented and are in the process of being tested during the 1994 flight season. These include the following innovations: A direct observation of a laboratory radiance standard is now used to double check the wide field-of-view calibration via an integrating sphere source. Launch site field calibration of the AVIRIS sensor is now being planned to augment the laboratory and inflight calibration. Modification to a dry air conditioning unit has been made to enable ground calibration at flight operating temperatures. One hundred lines of dark imagery has been added to the end of each flight line to assist in the analysis and removal of residual coherent noise. The intensity of the onboard calibration lamp has been modified to improve response in the blue end of the spectrum. Novel spectral filters have been installed in the onboard calibration source.

Airborne Visible/Infrared Imaging Spectrometer Cal↗

Differential Processing of Low and High LET Radiation Induced DNA Damage: Investigation of Switch from ATM to ATR Signaling

The members of the phosphatidylinositol kinase-like kinase family of proteins namely ataxia-telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR) are directly responsible for the maintenance of genomic integrity by mounting DDR through signaling and facilitating the recruitment of repair factors at the sites of DNA damage along with coordinating the deployment of cell cycle checkpoints to permit repair by phosphorylating Checkpoint kinase Chk1, Chk2 and p53. High LET radiation from GCR (Galactic Cosmic Rays) consisting mainly of protons and high energy and charged (HZE) particles from SPE (Solar Particle Event) pose a major health risk for astronauts on their space flight missions. The determination of these risks and the design of potential safeguards require sound knowledge of the biological consequences of lesion induction and the capability of the cells to counter them. We here strive to determine the coordination of ATM and ATR kinases at the break sites directly affecting checkpoint signaling and DNA repair and whether differential processing of breaks induced by low and high LET radiation leads to possible augmentation of swap of these damage sensors at the sites of DNA damage. Exposure of cells to IR triggers rapid autophosphorylation of serine-1981 that causes dimer dissociation and initiates monomer formation of ATM. ATM kinase activity depends on the disruption of the dimer, which allows access and phosphorylation of downstream ATM substrates like Chk2. Evidence suggests that ATM is activated by the alterations in higher-order chromatin structure although direct binding of ATM to DSB ends may be a crucial step in its activation. On the other hand, in case of ATR, RPA (replication protein A)-coated ssDNA (single-stranded DNA) generated as a result of stalled DNA replication or during processing of chromosomal lesions is crucial for the localization of ATR to sites of DNA damage in association with ATR-interacting protein (ATRIP). Although the majority of RPA-coated ssDNA is generally present only during DNA replication, ATR activation in G1 and G2-phase might still require formation of RPA-coated ssDNA, probably initiated by the MRN-CtIP complex and then extended by the Exo1- or BLM-dependent mechanisms at the sites of DSBs. Evidence accumulates that activation of ATM and ATR are oppositely regulated by the length of single stranded overhangs generated at the break sites by processes mentioned above and these stretches of single stranded overhangs hold the clue for ATM to ATR switch at broken DNA ends. We irradiated 82-6hTERT human fibroblast cells with low LET gamma-rays and high LET Fe and Si particles. Preliminary results with cells exposed to 1Gy gamma-rays show that the kinetics of pChk2-pT68 foci formation is comparable to that of gamma-H2AX although they appear to recede quicker. The number and intensity of observed foci reaches a maximum at 30 min and 60 min post IR for Chk2-pT68 and gamma-H2AX foci respectively and all Chk2-pT68 foci colocalize with gamma-H2AX foci. The kinetics of Chk1-pS345 and ATRIP are being determined. Results of Chk2-pT68 foci kinetics was also corroborated by western blot experiments, although phosphorylation was detected as early as 10 min and started receding 30 min post IR with 2Gy of gamma-rays. On the other hand, level of ATR-pS428 reached its maximum between 60 and 120 min and was maintained until the last measured time point of 4 hours post IR as determined by western blotting. Experiments performed with high LET Fe and Si particles will be reported.

Saha, Janapriya↗

Earth observation system: Spacecraft design

The Earth Observation Satellite (EOS) was a study funded by NASA Langley Research Center. The study was a system investigation of the total spacecraft integration with its major subsystems and sensors. Mission optimization and ranking using various sensors was also an objective of the contract. Integrating the spacecraft and major subsystems with the large microwave radiometer was done, essentially making the radiometer a free-flyer without an external spacecraft. Another program objective was to provide design and analysis data on microwave radiometer satellites augmented with additional Earth, ocean, and atmospheric sensors. A top-down systems approach resulted in a detailed design integrating subsystems and sensors into the microwave support structure. An important objective of the program was to identify technology needs for Earth observation satellites. The definition and understanding of these design drivers are critical in order to set priorities for future EOS work.

Herbert, J. J.↗

Compliant Tactile Sensors

Tactile sensors are currently being designed to sense interactions with human hands or pen-like interfaces. They are generally embedded in screens, keyboards, mousepads, and pushbuttons. However, they are not well fitted to sense interactions with all kinds of objects. A novel sensor was originally designed to investigate robotics manipulation where not only the contact with an object needs to be detected, but also where the object needs to be held and manipulated. This tactile sensor has been designed with features that allow it to sense a large variety of objects in human environments. The sensor is capable of detecting forces coming from any direction. As a result, this sensor delivers a force vector with three components. In contrast to most of the tactile sensors that are flat, this one sticks out from the surface so that it is likely to come in contact with objects. The sensor conforms to the object with which it interacts. This augments the contact's surface, consequently reducing the stress applied to the object. This feature makes the sensor ideal for grabbing objects and other applications that require compliance with objects. The operational range of the sensor allows it to operate well with objects found in peoples' daily life. The fabrication of this sensor is simple and inexpensive because of its compact mechanical configuration and reduced electronics. These features are convenient for mass production of individual sensors as well as dense arrays. The biologically inspired tactile sensor is sensitive to both normal and lateral forces, providing better feedback to the host robot about the object to be grabbed. It has a high sensitivity, enabling its use in manipulation fingers, which typically have low mechanical impedance in order to be very compliant. The construction of the sensor is simple, using inexpensive technologies like silicon rubber molding and standard stock electronics.

Torres-Jara, Eduardo R.↗

Hybrid Reality Lab Capabilities - Video 2

Our Hybrid Reality and Advanced Operations Lab is developing incredibly realistic and immersive systems that could be used to provide training, support engineering analysis, and augment data collection for various human performance metrics at NASA. To get a better understanding of what Hybrid Reality is, let's go through the two most commonly known types of immersive realities: Virtual Reality, and Augmented Reality. Virtual Reality creates immersive scenes that are completely made up of digital information. This technology has been used to train astronauts at NASA, used during teleoperation of remote assets (arms, rovers, robots, etc.) and other activities. One challenge with Virtual Reality is that if you are using it for real time-applications (like landing an airplane) then the information used to create the virtual scenes can be old (i.e. visualized long after physical objects moved in the scene) and not accurate enough to land the airplane safely. This is where Augmented Reality comes in. Augmented Reality takes real-time environment information (from a camera, or see through window, and places digitally created information into the scene so that it matches with the video/glass information). Augmented Reality enhances real environment information collected with a live sensor or viewport (e.g. camera, window, etc.) with the information-rich visualization provided by Virtual Reality. Hybrid Reality takes Augmented Reality even further, by creating a higher level of immersion where interactivity can take place. Hybrid Reality takes Virtual Reality objects and a trackable, physical representation of those objects, places them in the same coordinate system, and allows people to interact with both objects' representations (virtual and physical) simultaneously. After a short period of adjustment, the individuals begin to interact with all the objects in the scene as if they were real-life objects. The ability to physically touch and interact with digitally created objects that have the same shape, size, location to their physical object counterpart in virtual reality environment can be a game changer when it comes to training, planning, engineering analysis, science, entertainment, etc. Our Project is developing such capabilities for various types of environments. The video outlined with this abstract is a representation of an ISS Hybrid Reality experience. In the video you can see various Hybrid Reality elements that provide immersion beyond just standard Virtual Reality or Augmented Reality.

Delgado, Francisco J.↗

Optimization of multispectral sensors for bathymetry applications

The Naval Oceanographic office has proposed to augment current capabilities with an airborne MSS system capable of conducting hydrographic surveys of shallow and clear oceanic waters for purposes of determining ocean depth and identifying marine hazards. Recent efforts have concentrated on development of an active/passive system, where the active system will be used to calibrate a passive multispectral sensor. In this paper, parameters which influence collection-system design and depth-extraction techniques have been used to describe the practical bounds to which MSS technology can support coastal bathymetric surveying. Performance is estimated in terms of expected S/N and depth-extraction errors.

Tanis, F. J.↗

Early Artemis Surface Navigation: Challenges, Approaches, and Opportunities

The early Artemis missions represent the return of humanity to the surface of the Moon and provide opportunities for meeting early science and exploration goals. Position, Navigation, and Timing (PNT) capabilities are a fundamental element and inform operational design, flight rules, and the ability to meet these. This paper provides an overview of the needs, potential implementations, challenges, and concepts of operations in the initial human surface missions, Artemis III and IV. These early excursions are a crucial learning opportunity to gain more experience in the actual operational environment for Artemis V and beyond where exploration objectives and complexity increases. As part of the study, the team defined a threshold performance navigation requirement (including position and orientation) to meet crew safe return and assessed a breadth of navigation approaches that could be deployed to augment the crew’s baseline navigation capability. Data was collected in terms of size, mass, power, operational constraints, environment constraints, interface, and performance to define the technical metrics. Given these, the trade team conducted polling among the various Artemis Campaign elements to capture preference, integration challenges, and operational impacts. These were used to develop weightings and inform a ranked order of solutions across each of the early missions. The results of the study recommended augmenting the initial orientation capability with additional navigation sensors to provide coarse position and heading information to the crew to enable a safe contingency walk-back when out of video range. The team identified opportunities for embedding this hardware in future scenarios to provide an integrated solution. With the deployment of the LunaNet’s Lunar Augmented Navigation System, the crew will be able to maintain accurate real-time navigation knowledge with minimal physical impacts. Discussion of future testing and continued analysis is included in this paper. These forward plans and long-term architecture systems will enable a powerful navigation approach for orbiting and surface users, enabling a high level of scientific return and crew safety.

Evan Anzalone↗

Early Artemis Surface Navigation: Challenges, Approaches, and Opportunities

The early Artemis missions represent the return of humanity to the surface of the Moon and provide opportunities for meeting early science and exploration goals. Position, Navigation, and Timing (PNT) capabilities are a fundamental element and inform operational design, flight rules, and the ability to meet these. This paper provides an overview of the needs, potential implementations, challenges, and concepts of operations in the initial human surface missions, Artemis III and IV. These early excursions are a crucial learning opportunity to gain more experience in the actual operational environment for Artemis V and beyond where exploration objectives and complexity increases. As part of the study, the team defined a threshold performance navigation requirement (including position and orientation) to meet crew safe return and assessed a breadth of navigation approaches that could be deployed to augment the crew’s baseline navigation capability. Data was collected in terms of size, mass, power, operational constraints, environment constraints, interface, and performance to define the technical metrics. Given these, the trade team conducted polling among the various Artemis Campaign elements to capture preference, integration challenges, and operational impacts. These were used to develop weightings and inform a ranked order of solutions across each of the early missions. The results of the study recommended augmenting the initial orientation capability with additional navigation sensors to provide coarse position and heading information to the crew to enable a safe contingency walk-back when out of video range. The team identified opportunities for embedding this hardware in future scenarios to provide an integrated solution. With the deployment of the LunaNet’s Lunar Augmented Navigation System, the crew will be able to maintain accurate real-time navigation knowledge with minimal physical impacts. Discussion of future testing and continued analysis is included in this paper. These forward plans and long-term architecture systems will enable a powerful navigation approach for orbiting and surface users, enabling a high level of scientific return and crew safety.

Evan Anzalone↗

Application of a Physics-Informed Convolutional Neural Network for Monitoring the Temperature Fields in High-Temperature Gas Reactors

Here, this work presents current advances in applying a physics-informed convolutional neural network (CNN) to evaluate temperature distributions in advanced reactors. Our goal is to demonstrate that the CNN can reconstruct temperature fields within the solid region of a prismatic fuel assembly in a high-temperature gas reactor (HTGR) with sensor data available in only a few cooling channels. Before that, we showcase the superior performance of the physics-informed CNN in comparison to a purely data-driven multilayer perceptron (MLP), considering a canonical heated channel setup. This analysis shows the advantages of our approach and justifies its choice. The datasets employed here are obtained upon numerical simulations performed with codes under the Nuclear Energy Advanced Modeling and Simulation program. This work is important, as industry experience indicates that the assembly material in HTGR concepts is prone to large thermal-mechanical loads nearing operational limits. This makes it crucial to characterize peak temperatures and their distributions near hot spots. Modern thermocouples are unreliable in these types of harsh environments because of the high neutron fluxes and elevated temperatures involved. The CNN-based field reconstruction represents an attractive solution, enabling sensor arrays in less aggressive locations and augmenting indirect predictions for less accessible regions. The results show that the CNN reduces prediction errors by orders of magnitude in comparison to the MLP, considering the simple yet well-representative heated channel case. In the case of the HTGR fuel assembly, the CNN can successfully reconstruct temperature fields over various cooling regimes. Furthermore, we also explore the algorithm’s ability to detect abnormalities. Interestingly, the CNN proves it has the capacity to detect blockage in one of the noninstrumented cooling channels.

Machine learning↗

Flight data processing with the F-8 adaptive algorithm

An explicit adaptive control algorithm based on maximum likelihood estimation of parameters has been designed for NASA's DFBW F-8 aircraft. To avoid iterative calculations, the algorithm uses parallel channels of Kalman filters operating at fixed locations in parameter space. This algorithm has been implemented in NASA/DFRC's Remotely Augmented Vehicle (RAV) facility. Real-time sensor outputs (rate gyro, accelerometer and surface position) are telemetered to a ground computer which sends new gain values to an on-board system. Ground test data and flight records were used to establish design values of noise statistics and to verify the ground-based adaptive software. The software and its performance evaluation based on flight data are described

Hartmann, G.↗