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NASA NTRS2002

Defect Localization Capabilities of a Global Detection Scheme: Spatial Pattern Recognition Using Full-field Vibration Test Data in Plates

Recently, a conceptually simple approach, based on the notion of defect energy in material space has been developed and extensively studied (from the theoretical and computational standpoints). The present study focuses on its evaluation from the viewpoint of damage localization capabilities in case of two-dimensional plates; i.e., spatial pattern recognition on surfaces. To this end, two different experimental modal test results are utilized; i.e., (1) conventional modal testing using (white noise) excitation and accelerometer-type sensors and (2) pattern recognition using Electronic speckle pattern interferometry (ESPI), a full field method capable of analyzing the mechanical vibration of complex structures. Unlike the conventional modal testing technique (using contacting accelerometers), these emerging ESPI technologies operate in a non-contacting mode, can be used even under hazardous conditions with minimal or no presence of noise and can simultaneously provide measurements for both translations and rotations. Results obtained have clearly demonstrated the robustness and versatility of the global NDE scheme developed. The vectorial character of the indices used, which enabled the extraction of distinct patterns for localizing damages proved very useful. In the context of the targeted pattern recognition paradigm, two algorithms were developed for the interrogation of test measurements; i.e., intensity contour maps for the damaged index, and the associated defect energy vector field plots.

Saleeb, A. F.↗

NASA NTRS1999

Recovery of postural equilibrium control following space flight

DSO 605 represents the first large study of balance control following spaceflight. Data collected during DSO 605 confirm the theory that postural ataxia following short duration spaceflight is of vestibular origin. We used the computerized dynamic posturography technique developed by Nashner et al. to study the role of the vestibular system in balance control in astronauts during quiet stance before and after spaceflight. Our results demonstrate unequivocally that balance control is disrupted in all astronauts immediately after return from space. The most severely affected returning crew members performed in the same way as vestibular deficient patients exposed to this test battery. We conclude that otolith mediated spatial reference provided by the terrestrial gravitational force vector is not used by the astronauts balance control systems immediately after spaceflight. Because the postflight ataxia appears to be mediated primarily by CNS adaptation to the altered vestibular inputs caused by loss of gravitational stimulation, we believe that intermittent periods of exposure to artificial gravity may provide an effective in-flight countermeasure. Specifically, we propose that in-flight centrifugation will allow crew members to retain their terrestrial sensory-motor adapted states while simultaneously developing microgravity adapted states. The dual-adapted astronaut should be able to make the transition from microgravity to unit gravity with minimal sensory-motor effects. We have begun a ground based program aimed at developing short arm centrifuge prescriptions designed to optimize adaptation to altered gravitational environments. Results from these experiments are expected to lead directly to in-flight evaluation of the proposed centrifuge countermeasure. Because our computerized dynamic posturography system was able to (1) quantify the postflight postural ataxia reported by crew members and observed by flight surgeons and scientists, (2) track the recovery of normal (preflight) balance control, (3) differentiate between rookie and veteran subjects, and (4) provide normative and clinical databases for comparison, and because our study successfully characterized postflight balance control recovery in a large cross-section of Shuttle crew members, we recommend that this system and protocol be adopted as a standard dependent measure for evaluating the efficacy of countermeasures and/or evaluating the postflight effects of changing mission durations or activities.

Paloski, William H.↗

NASA NTRS2008

Split-Block Waveguide Polarization Twist for 220 to 325 GHz

A split-block waveguide circuit that rotates polarization by 90 has been designed with WR-3 input and output waveguides, which are rectangular waveguides used for a nominal frequency range of 220 to 325 GHz. Heretofore, twisted rectangular waveguides equipped with flanges at the input and output have been the standard means of rotating the polarizations of guided microwave signals. However, the fabrication and assembly of such components become difficult at high frequency due to decreasing wavelength, such that twisted rectangular waveguides become impractical at frequencies above a few hundred gigahertz. Conventional twisted rectangular waveguides are also not amenable to integration into highly miniaturized subassemblies of advanced millimeter- and submillimeter-wave detector arrays now undergoing development. In contrast, the present polarization- rotating waveguide can readily be incorporated into complex integrated waveguide circuits such as miniaturized detector arrays fabricated by either conventional end milling of metal blocks or by deep reactive ion etching of silicon blocks. Moreover, the present split-block design can be scaled up in frequency to at least 5 THz. The main step in fabricating a splitblock polarization-rotating waveguide of the present design is to cut channels having special asymmetrically shaped steps into mating upper and lower blocks (see Figure 1). The dimensions of the steps are chosen to be consistent with the WR-3 waveguide cross section, which is 0.864 by 0.432 mm. The channels are characterized by varying widths with constant depths of 0.432, 0.324, and 0.216 mm and by relatively large corner radii to facilitate fabrication. The steps effect both a geometric transition and the corresponding impedance-matched electromagnetic-polarization transition between (1) a WR-3 rectangular waveguide oriented with the electric field vector normal to the block mating surfaces and (2) a corresponding WR-3 waveguide oriented with its electric field vector parallel to the mating surfaces of the blocks. A prototype has been built and tested. Figure 2 presents test results indicative of good performance over nearly the entire WR-3 waveguide frequency band.

Ward, John↗

NASA NTRS2016

COWVR Instrument Antenna, Performance Verification and Test Results

This paper describes the test campaign and the results used to verify the performance of the Compact Ocean Wind Vector Radiometer (COWVR) instrument antenna. Developed as a proof-of-concept technology demonstration mission, it’s planned for launch in 2016. Using small mass and low power, when compared to other instruments with similar capabilities, COWVR promises to obtain the same wind vector retrieval accuracy. COWVR was designed and developed at Jet Propulsion Laboratory (JPL) in collaboration with the US Air Force Space Missile Command.

off-set reflector↗

DOE OSTI2024

Cosmic Shear Analysis of the DECam Local Volume Exploration Survey

We forecast cosmological constraints and develop a cosmic shear analysis pipeline for the DECam Local Volume Exploration Survey (DELVE). We test the effects of two different intrinsic alignment frameworks (TATT and NLA) on synthetic data vectors. In addition, we examine the impact of baryon contamination and determine the necessary scale cuts to reduce its influence. We find the forecast results to be as constraining as the DES Y3 cosmological parameter measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS2005

Chapter 24 - Propulsion

This chapter provides a basic guide to the flight testing of propulsion system operability and compatibility (O&C). For the purposes of establishing a frame of reference, O&C refers to the ability of the aircrew to establish and maintain the desired level of propulsion system net propulsive force throughout the operating envelope of the aircraft. For the purposes of definition, net propulsive force is used to refer to the vector resultant of all throttle dependant forces acting upon the aircraft. By limiting the discussion in this Section to flight testing of the O&C of the propulsion system, it should not be interpreted to mean that these are the only factors that need to be considered when conducting flight test to evaluate an aircraft propulsion system. Propulsion system structural interfaces, pneumatic interfaces, mechanical interfaces, hydraulic interfaces, thermodynamic interfaces and electrical interfaces must all be evaluated prior to or concurrently with the O&C test program in order to ensure a safe and effective flight test program of the aircraft and propulsion system.

Lawrence A Thomas↗

DOE OSTI2017

Solar Flare Prediction Model with Three Machine-learning Algorithms using Ultraviolet Brightening and Vector Magnetograms

We developed a flare prediction model using machine learning, which is optimized to predict the maximum class of flares occurring in the following 24 hr. Machine learning is used to devise algorithms that can learn from and make decisions on a huge amount of data. We used solar observation data during the period 2010–2015, such as vector magnetograms, ultraviolet (UV) emission, and soft X-ray emission taken by the Solar Dynamics Observatory and the Geostationary Operational Environmental Satellite . We detected active regions (ARs) from the full-disk magnetogram, from which ∼60 features were extracted with their time differentials, including magnetic neutral lines, the current helicity, the UV brightening, and the flare history. After standardizing the feature database, we fully shuffled and randomly separated it into two for training and testing. To investigate which algorithm is best for flare prediction, we compared three machine-learning algorithms: the support vector machine, k-nearest neighbors (k-NN), and extremely randomized trees. The prediction score, the true skill statistic, was higher than 0.9 with a fully shuffled data set, which is higher than that for human forecasts. It was found that k-NN has the highest performance among the three algorithms. The ranking of the feature importance showed that previous flare activity is most effective, followed by the length of magnetic neutral lines, the unsigned magnetic flux, the area of UV brightening, and the time differentials of features over 24 hr, all of which are strongly correlated with the flux emergence dynamics in an AR.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2020

Drug Resistance in Filarial Parasites Does Not Affect Mosquito Vectorial Capacity

Parasite drug resistance presents a major obstacle to controlling and eliminating vector-borne diseases affecting humans and animals. While vector-borne disease dynamics are affected by factors related to parasite, vertebrate host and vector, research on drug resistance in filarial parasites has primarily focused on the parasite and vertebrate host, rather than the mosquito. However, we expect that the physiological costs associated with drug resistance would reduce the fitness of drug-resistant vs. drug-susceptible parasites in the mosquito wherein parasites are not exposed to drugs. Here we test this hypothesis using four isolates of the dog heartworm (Dirofilaria immitis)—two drug susceptible and two drug resistant—and two vectors—the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Ae. albopictus)—as our model system. Our data indicated that while vector species had a significant effect on vectorial capacity, there was no significant difference in the vectorial capacity of mosquitoes infected with drug-resistant vs. drug-susceptible parasites. Consequently, contrary to expectations, our data indicate that drug resistance in D. immitis does not appear to reduce the transmission efficiency of these parasites, and thus the spread of drug-resistant parasites in the vertebrate population is unlikely to be mitigated by reduced fitness in the mosquito vector.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2021

Vector bosons and jets in proton collisions

Events with vector bosons produced in association with jets have been extensively studied at hadron colliders and provide high-accuracy tests of the standard model. A good understanding of these processes is of paramount importance for precision Higgs physics, as well as for searches for new physics. In particular, associated production of γ, W, or Z bosons with light-flavor and heavy-flavor jets is a powerful tool for testing perturbative QCD calculations, Monte Carlo event generators, and can also constrain the parametrizations used to describe the parton content of the proton. Furthermore, events with a W or Z boson produced with two well-separated jets can be used to distinguish between electroweak and strong production mechanisms, and to set limits on contributions of physics beyond the standard model. This review summarizes the historical theoretical developments and the state-of-the-art in the modeling of vector-boson-plus-jet physics while focusing on experimental results by the LHC collaborations in run 1 and run 2 and including comparisons with recent measurements at the Tevatron.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS2005

A Computational Study of a New Dual Throat Fluidic Thrust Vectoring Nozzle Concept

A computational investigation of a two-dimensional nozzle was completed to assess the use of fluidic injection to manipulate flow separation and cause thrust vectoring of the primary jet thrust. The nozzle was designed with a recessed cavity to enhance the throat shifting method of fluidic thrust vectoring. Several design cycles with the structured-grid, computational fluid dynamics code PAB3D and with experiments in the NASA Langley Research Center Jet Exit Test Facility have been completed to guide the nozzle design and analyze performance. This paper presents computational results on potential design improvements for best experimental configuration tested to date. Nozzle design variables included cavity divergence angle, cavity convergence angle and upstream throat height. Pulsed fluidic injection was also investigated for its ability to decrease mass flow requirements. Internal nozzle performance (wind-off conditions) and thrust vector angles were computed for several configurations over a range of nozzle pressure ratios from 2 to 7, with the fluidic injection flow rate equal to 3 percent of the primary flow rate. Computational results indicate that increasing cavity divergence angle beyond 10 is detrimental to thrust vectoring efficiency, while increasing cavity convergence angle from 20 to 30 improves thrust vectoring efficiency at nozzle pressure ratios greater than 2, albeit at the expense of discharge coefficient. Pulsed injection was no more efficient than steady injection for the Dual Throat Nozzle concept.

Deere, Karen A.↗

NASA NTRS1991

Quaternion normalization in additive EKF for spacecraft attitude determination

This work introduces, examines, and compares several quaternion normalization algorithms, which are shown to be an effective stage in the application of the additive extended Kalman filter (EKF) to spacecraft attitude determination, which is based on vector measurements. Two new normalization schemes are introduced. They are compared with one another and with the known brute force normalization scheme, and their efficiency is examined. Simulated satellite data are used to demonstrate the performance of all three schemes. A fourth scheme is suggested for future research. Although the schemes were tested for spacecraft attitude determination, the conclusions are general and hold for attitude determination of any three dimensional body when based on vector measurements, and use an additive EKF for estimation, and the quaternion for specifying the attitude.

Bar-Itzhack, I. Y.↗

NASA NTRSDate not supplied

Acoustic Flight Test of the Joby Aviation Advanced Air Mobility Prototype Vehicle

An extensive acoustic flight test was performed on the Joby Aviation pre-production all-electric vertical takeoff and landing prototype. With the design intent of carrying a pilot and four passengers a maximum range of 150 miles, this vehicle utilizes distributed propulsion and vectored thrust via six tilting propellers. As part of the Advanced Air Mobility (AAM) National Campaign, this is the first full-scale AAM aircraft tested by NASA over representative conditions for all phases of a typical mission profile. A 58- channel distributed microphone array was used to acquire acoustic measurements on more than 100 test points (31 unique conditions). The measurements were postprocessed with synchronously sampled vehicle position and state data to form ground noise contours of departures and approaches at various flight path angles and accelerations. Comparing ground areas of 75 dBA isolines, approaches consistently exhibit higher noise levels rela- tive to departures. Directivity maps were generated for constant airspeed level flyovers. Examples comparing the differences in a semi-thrust borne and full wing-borne mode are given, with full wing-borne mode representing the quietest phase of the flight envelope tested. Measurements for hover in and out of ground effect are given and found to have 2 to 5 dB variation over a single run, and more significant variation between back-to-back runs. Finally, initial analysis of acoustic symmetry about the longitudinal vehicle axis and repeatability over several test days are presented.

Acoustics↗

DOE OSTI2020

Comparison of Magnetic Field Emission from Unipolar and Bipolar Coil-Based Wireless Charging Systems

In this study, the leakage magnetic field (LMF) from the unipolar (circular, rectangular, etc.) and bipolar (double-D) coil-based wireless charging systems (WCSs) are investigated and compared. The unipolar and bipolar pads, which are the two most widely adopted charging-pads, have significantly different magnetic field emission characteristics. In this paper, the spatial-distribution and vector-pattern of the leakage magnetic field are studied and compared for similar 11 kW unipolar and bipolar coil-based WCSs. The field emissions are simulated using finite element analysis (FEA) and tested experimentally with an 11 kW bipolar coil-based WCS prototype. The results show that the leakage magnetic field of the unipolar and bipolar pads have widely different vector-orientation and spatial distributions of the leakage magnetic field. The results show that the unipolar coil based WCS has a dominant vertical and the bipolar pads coil-based WCS has dominant horizontally aligned leakage magnetic field. Considering the shielding, the aluminum plate is found highly effective for the unipolar pad and almost ineffective for bipolar pads.

Mohammad, Mostak↗

NASA NTRS2010

NASA Ares I Launch Vehicle First Stage Roll Control System Cold Flow Development Test Program Overview

The Ares I launch vehicle is the selected design, chosen to return humans to the moon, Mars, and beyond. It is configured in two inline stages: the First Stage is a Space Shuttle derived five-segment Solid Rocket Booster and the Upper Stage is powered by a Saturn V derived J-2X engine. During launch, roll control for the First Stage (FS) is handled by a dedicated Roll Control System (RoCS) located on the connecting Interstage. That system will provide the Ares I with the ability to counteract induced roll torque while any induced yaw or pitch moments are handled by vectoring of the booster nozzle. This paper provides an overview of NASA s Ares I FS RoCS cold flow development test program including detailed test objectives, types of tests run to meet those objectives, an overview of the results, and applicable lessons learned. The test article was built and tested at the NASA Marshall Space Flight Center in Huntsville, AL. The FS RoCS System Development Test Article (SDTA) is a full scale, flight representative water flow test article whose primary objective was to obtain fluid system performance data to evaluate integrated system level performance characteristics and verify analytical models. Development testing and model correlation was deemed necessary as there is little historical precedent for similar large flow, pulsing systems such as the FS RoCS. The cold flow development test program consisted of flight-similar tanks, pressure regulators, and thruster valves, as well as plumbing simulating flight geometries, combined with other facility grade components and structure. Orifices downstream of the thruster valves were used to simulate the pressure drop through the thrusters. Additional primary objectives of this test program were to: evaluate system surge pressure (waterhammer) characteristics due to thruster valve operation over a range of mission duty cycles at various feed system pressures, evaluate temperature transients and heat transfer in the pressurization system, including regulator blowdown and propellant ullage performance, measure system pressure drops for comparison to analysis of tubing and components, and validate system activation and re-activation procedures for the helium pressurant system. Secondary objectives included: validating system processes for loading, unloading, and purging, validating procedures and system response for multiple failure scenarios, including relief valve operation, and evaluating system performance for contingency scenarios. The test results of the cold flow development test program are essential in validating the performance and interaction of the Roll Control System and anchoring analysis tools and results to a Critical Design Review level of fidelity.

Butt, Adam↗

DOE OSTI2017

Development of a high efficiency integration system and promoter library for rapid modification of Pseudomonas putida KT2440

Pseudomonas putida strains are highly robust bacteria known for their ability to efficiently utilize a variety of carbon sources, including aliphatic and aromatic hydrocarbons. Recently, P. putida has been engineered to valorize the lignin stream of a lignocellulosic biomass pretreatment process. Nonetheless, when compared to platform organisms such as Escherichia coli, the toolkit for engineering P. putida is underdeveloped. Heterologous gene expression in particular is problematic. Plasmid instability and copy number variance provide challenges for replicative plasmids, while use of homologous recombination for insertion of DNA into the chromosome is slow and laborious. Furthermore, heterologous expression efforts to date typically rely on overexpression of exogenous pathways using a handful of poorly characterized promoters. In order to improve the P. putida toolkit, we developed a rapid genome integration system using the site-specific recombinase from bacteriophage Bxb1 to enable rapid, high efficiency integration of DNA into the P. putida chromosome. We also developed a library of synthetic promoters with various UP elements, -35 sequences, and -10 sequences, as well as different ribosomal binding sites. We tested these promoters using a fluorescent reporter gene, mNeonGreen, to characterize the strength of each promoter, and identified UP-element-promoter-ribosomal binding sites combinations capable of driving a ~150-fold range of protein expression levels. One additional integrating vector was developed that confers more robust kanamycin resistance when integrated at single copy into the chromosome. This genome integration and reporter systems are extensible for testing other genetic parts, such as examining terminator strength, and will allow rapid integration of heterologous pathways for metabolic engineering.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Automated System-wide Event Detection and Classification Using Machine Learning on Synchrophasor Data

As the number of phasor measurement units (PMUs) deployed in a power system increases, and their data volume streamed to the control canter intensifies, operators are facing challenges related to the analysis of such data, which need to be observed and responded to as the measurements are displayed in the Control Room. Humans are generally unable to process such large amount of data efficiently and rapidly. There is an apparent need for automated ways to analyze the data, extract actionable information about occurrence of specific events, and characterize the events quickly and cost effectively. This paper discusses the use of machine learning (ML) to facilitate such tasks by providing automated, highly computationally efficient, and cost-effective ways of extracting actionable information from synchrophasor big data in real-time. We developed Big Data Smart (BDSmart) ML-based prototype tool for the Control Room use that automatically analyses data properties from synchrophasor system measurements taken across the three grid Interconnections in the USA (Western, Eastern and ERCOT). The data collected from several hundreds of PMUs located across the Interconnections over a period of two years have been made available for our extensive study. As a result, we were able to identify a number of big data properties that influence how ML methodology is applied to select, develop, train and test the data models that can eventually be used for the tool implementation. The resulting set of candidate algorithms spans unsupervised, supervised, semi-supervised and transfer-learning approaches. Many ML techniques, such as decision trees, multinomial logistic regression, feed-forward neural networks, K-nearest neighbor, multiclass support vector machine, and single and multi-channel convolutional neural networks, are implemented, and their performance is examined. We offer the results from testing the data models. The novelty of our study is in the approaches for bad data detection and mitigation, selection of a simplified feature for event detection, and data label improvements. As a result, we came up with a list of recommendations for the utilities on how to improve the PMU recording practices to cater to the future ML applications aimed at automating the analysis of synchrophasor data.

Synchrophasors, Machine Learning, System-wide Even↗

NASA NTRS1994

VSTOL Systems Research Aircraft (VSRA) Harrier

NASA's Ames Research Center has developed and is testing a new integrated flight and propulsion control system that will help pilots land aircraft in adverse weather conditions and in small confined ares (such as, on a small ship or flight deck). The system is being tested in the V/STOL (Vertical/Short Takeoff and Landing) Systems research Aircraft (VSRA), which is a modified version of the U.S. Marine Corps's AV-8B Harrier jet fighter, which can take off and land vertically. The new automated flight control system features both head-up and panel-mounted computer displays and also automatically integrates control of the aircraft's thrust and thrust vector control, thereby reducing the pilot's workload and help stabilize the aircraft for landing. Visiting pilots will be encouraged to test the new system and provide formal evaluation flights data and feedback. An actual flight test and the display panel of control system are shown in this video.

Source record↗

DOE OSTI2016

A refined methodology for stress inversions of earthquake focal mechanisms: Refined Stress Inversion Methodology

We develop an improved methodology for reliable high-resolution inversions of focal mechanisms to background stress field orientation and stress ratio R in two or three dimensions. The earthquake catalog is declustered to remove events likely affected strongly by local stress interactions rather than reflecting the large-scale background stress field. The declustered data are discretized with the k-means algorithm into groups containing a number of focal mechanisms between a minimum number N min and 2N min . Synthetic tests indicate that N min ≈ 30 provides stable inversion results under different stress regimes and noise conditions when R ≈ 0.5, while N min ≈ 45 is needed for R near 0 or 1. Additional synthetic tests compare the performance of selecting the fault plane of each focal mechanism using (a) the plane with lowest misfit angle between the slip vector from the focal mechanism and shear traction from the stress tensor and (b) the plane with highest instability coefficient representing proximity to the optimally oriented fault for given stress field and friction coefficient. The instability criterion is found to provide more accurate inversion results under all tested stress regimes, stress ratios, and noise conditions. The refined inversion methodology combines selecting fault planes using the instability criterion iteratively with a damped simultaneous inversion of different focal mechanism groups. Results characterizing neighborhoods of discretized domains merged during the damped inversion provide high-resolution information independent of the discretization. Some aspects of the methodology are illustrated with focal mechanism data from the San Jacinto Fault Zone in Southern California.

58 GEOSCIENCES↗