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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

SOWFA + Super Controller User's Manual

SOWFA + Super Controller is a modification of the NREL's SOWFA tool which allows for a user to apply multiturbine or centralized wind plant control algorithms within the high-fidelity SOWFA simulation environment. The tool is currently a branch of the main SOWFA program, but will one day will be merged into a single version. This manual introduces the tool and provides examples such that a user can implement their own super controller and set up and run simulations. The manual only discusses enough about SOWFA itself to allow for the customization of controllers and running of simulations, and details of SOWFA itself are reported elsewhere Churchfield and Lee (2013); Churchfield et al. (2012). SOWFA + Super Controller, and this manual, are in alpha mode.

17 WIND ENERGY↗
NASA NTRS1972

Improvement of a geodetic triangulation through control points established by means of satellite or precision traversing

Whether any significant increment to accuracy could be transferred from a super-control continental net (continental satellite net or super-transcontinental traverse) to the fundamental geodetic net (first-order triangulation) is discussed. This objective was accomplished by evaluating the positional accuracy improvement for a triangulation station, which is near the middle of the investigated geodetic triangulation net, by using various station constraints over its geodetic position. This investigation on a 1858 kilometer long triangulation chain shows that the super-control net can provide a useful constraint to the investigated geodetic triangulation net, and thus can improve it only when the accuracy of super-control net is at least 1 part in 500,000.

Saxena, N. K.↗
DOE OSTI2015

Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only in the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. As a result, with the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

FAST.Farm [SWR-17-56]

FAST.Farm is a multi-physics engineering tool for predicting the performance and loads of wind turbines within a wind farm. FAST.Farm uses FAST to solve the aero-hydro-servo-elastic dynamics of an individual turbine, but adds additional physics for wind farm-wide ambient wind in the atmospheric boundary layer; a wind-farm super controller; and wake deficits, advection, deflection, meandering, and merging. FAST.Farm is based on the principles of the Dynamic Wake Meandering (DWM) model—including passive tracer modeling of wake meandering—but addresses many of the limitations of previous DWM limitations. FAST.Farm maintains a low computational cost to the often highly iterative and probabilistic design process. Applications of FAST.Farm include reducing wind farm underperformance and loads uncertainty, developing wind farm controls to enhance operation, optimizing wind farm siting and topology, and innovating the design of wind turbines for the wind-farm environment.

Jonkman, Jason↗
NASA NTRS1972

Basic research and data analysis for the National Geodetic Satellite Program

Investigations of triangulation nets and scaling are reported. Adjustment of the BC-4 worldwide geometric satellite triangulation net is described, along with procedures for correcting type II data and the contents of magnetic tapes containing data from the Pageos network. Computational steps for the further reduction of partially reduced satellite image plate coordinates are outlined. The problem of improving existing triangulation systems by means of satellite super-control points was studied. The SAO-69 geometric solution was scaled with C-band radar data, resulting in SAO and C-band adjustment compatible with one another in the Western Hemisphere. The North America solution NA-6, obtained from GEOS 1 data, was readjusted with new heights as constraints on all 30 optical stations and is referred to as the NA-8 solution.

Source record↗
NASA NTRS1972

Basic research and data analysis for the National Geodetic Satellite program and for the Earth Surveys program

Current research is reported on precise and accurate descriptions of the earth's surface and gravitational field and on time variations of geophysical parameters. A new computer program was written in connection with the adjustment of the BC-4 worldwide geometric satellite triangulation net. The possibility that an increment to accuracy could be transferred from a super-control net to the basic geodetic (first-order triangulation) was investigated. Coordinates of the NA9 solution were computed and were transformed to the NAD datum, based on GEOS 1 observations. Normal equations from observational data of several different systems and constraint equations were added and a single solution was obtained for the combined systems. Transformation parameters with constraints were determined, and the impact of computers on surveying and mapping is discussed.

Source record↗
NASA NTRS2021

ExEP: Initial super-Nyquist wavefront control experiments in the Decadal Survey Testbed

In order to characterize exoplanets around nearby stars, upcoming and proposed space telescopes are being designed with high contrast coronagraph instruments. Coronagraphs are generally designed to suppress only a single, on-axis star, but there are numerous binary star systems within our observational range. Multi-star wavefront correction (MSWC) is a technique that uses deformable mirror(s) to simultaneously suppress light from more than one star to create a high contrast dark zone in the image. MSWC has already been well demonstrated in simulation and in air-based testbeds. In this paper, we describe our prepatory vacuum experiments in the Decadal Survey Testbed (DST) at the Jet Propulsion Laboratory. First we implemented super-Nyquist wavefront control (SNWC, a critical component of MSWC), and then we proceeded to simultaneous sub- and super-Nyquist control. With our existing calibration methods, SNWC reached a contrast of $8.6{\times}10^{-9}$ in a 10\% bandpass around a first-order diffraction spot; calibration improvements are needed to improve model agreement for higher-order spots. We have also implemented changes to our software (the open-source package FALCO) required for MSWC, and identified the necessary changes in hardware. Here we report our best SNWC lab results and our plans for implementing MSWC during a future set of experiments.

Bendek, Eduardo↗
DOE OSTI2016

Deformation of a super-elastic NiTiNb alloy with controllable stress hysteresis

Room temperature deformation of a Ni{sub 46.7}Ti{sub 42.8}Nb{sub 10.5} alloy was studied by in-situ synchrotron X-ray diffraction. Compared to binary NiTi alloy, the Nb dissolved in the matrix significantly increased the onset stress for Stress-Induced Martensite Transformation (SIMT). The secondary phase, effectively a Nb-nanowire dispersion in a NiTi-Nb matrix, increased the elastic stiffness of the bulk material, reduced the strain anisotropy in austenite families by load sharing during SIMT, and increased the stress hysteresis by resisting reverse phase transformation during unloading. The stress hysteresis can be controlled over a wide range by heat treatment through its influences on the residual stress of the Nb-nanowire dispersion and the stability of the austenite.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Super Strypi Navigation, Guidance & Control (NGC) v. Release 04

The Super Strypi Navigation, Guidance & Control Software is a real-time implementation of the navigation, guidance and control algorithms designed to deliver a payload to a desired orbit for the rail launched Super Strypi launch vehicle. The software contains all flight control algorithms required from pre-launch until orbital insertion. The flight sequencer module calls the NG&C functions at the appropriate times of flight. Additional functionality includes all the low level drivers and I/O for communicating to other systems within the launch vehicle and to the ground support equipment. The software is designed such that changes to the launch location and desired orbit can be changed without recompiling the code.

Anderson, Mark A.↗
DOE OSTI2015

TECHNIQUES FOR HIGH-CONTRAST IMAGING IN MULTI-STAR SYSTEMS. I. SUPER-NYQUIST WAVEFRONT CONTROL

Direct imaging of extra-solar planets is now a reality with the deployment and commissioning of the first generation of specialized ground-based instruments (GPI, SPHERE, P1640, and SCExAO). These systems allow of planets 10{sup 7} times fainter than their host star. For space-based missions (EXCEDE, EXO-C, EXO-S, WFIRST), various teams have demonstrated laboratory contrasts reaching 10{sup −10} within a few diffraction limits from the star. However, all of these current and future systems are designed to detect faint planets around a single host star, while most non-M-dwarf stars such as Alpha Centauri belong to multi-star systems. Direct imaging around binaries/multiple systems at a level of contrast allowing detection of Earth-like planets is challenging because the region of interest is contaminated by the host star's companion in addition to the host itself. Generally, the light leakage is caused by both diffraction and aberrations in the system. Moreover, the region of interest usually falls outside the correcting zone of the deformable mirror (DM) with respect to the companion. Until now, it has been thought that removing the light of a companion star is too challenging, leading to the exclusion of many binary systems from target lists of direct imaging coronographic missions. In this paper, we will show new techniques for high-contrast imaging of planets around multi-star systems and detail the Super-Nyquist Wavefront Control (SNWC) method, which allows wavefront errors to be controlled beyond the nominal control region of the DM. Our simulations have demonstrated that, with SNWC, raw contrasts of at least 5 × 10{sup −9} in a 10% bandwidth are possible.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Development of a super high speed motor-generator and controller

To develop a super high speed motor-generator, it is essential to deal with magnetic analysis, dynamic analysis, and experimental evaluation of the heart of the MTG (Microturbine Generator) system, the motor-generator. An amorphous core is applied to a stator core for reduction of iron loss at high speed, and the motor-generator is analyzed with considerations focused on magnetic losses and the statistical optimum design. The performance of the amorphous core is validated by the analysis and experiment by back-to-back tests considering the AC load. Rotor dynamics is performed for dynamic stability at high speed using transient analysis orbit diagrams and compared with the experimental results. The simulation results of the generator are compared with the experiment. Also a super high speed controller of the MTG system is developed using a sensorless algorithm, power stack, gate driver, digital signal processing, analog circuit, and radiation heat design. Based on these results, a high speed motor-generator and controller are successfully developed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Demonstration of Super-X divertor exhaust control for transient heat load management in compact fusion reactors

Nuclear fusion could offer clean, abundant energy. However, managing the power exhausted from the core fusion plasma towards the reactor wall remains a major challenge. This is compounded in emerging compact reactor designs promising more cost-effective pathways towards commercial fusion energy. Alternative Divertor Configurations (ADCs) are a potential solution. In this work, we demonstrate exhaust control in ADCs, employing a novel method to diagnose the neutral gas buffer, which shields the target. Our work on the Mega Ampere Spherical Tokamak Upgrade shows that ADCs tackle key risks and uncertainties for fusion energy. Their highly reduced sensitivity to perturbations enables active exhaust control in otherwise unfeasible situations and facilitates an increased passive absorption of transients, which would otherwise damage the divertor. We observe a strong decoupling of each divertor from other reactor regions, enabling near-independent control of the divertors and core plasma. Our work showcases the real-world benefits of ADCs for effective heat load management in fusion power reactors.

Imaging techniques↗
NASA NTRSDate not supplied

Multi-Star Wavefront Control with SCExAO Instrument: Demonstration with an Internal Source

Although only a small fraction of currently known exoplanets was found in binary and multiple systems, studies show that such stars do form planets, with an efficiency that is smaller, but within an order of magnitude of single stars. However, binaries are rarely considered as targets for exoplanet imaging space missions because of challenges of removing light from the second binary component. In our previous works it was shown how to solve two main issues that make exoplanet imaging in multiple systems impossible, namely, the mutual incoherence of speckles created by different binary components, and inability of a deformable mirror (DM) to control the starlight beyond the DM outer working angle/Nyquist limit. Feasibility of the developed Multi-Star Wavefront Control (MSWC) and Super-Nyquist Wavefront Control(SNWC) algorithms was demonstrated at the Ames Coronagraph Experiment (ACE) laboratory using a simple imaging system with a DM and no coronagraph. In this paper, we report the results our MSWC experiments using the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument that is part of our technology development effort. The main goal of these experiments is to validate MSWC on a real coronagraphic system by using an internal source to simulate at least one real representative binary target. In our demonstration narrow-band contrast of 4.1×10−6has been reached by using MSWC in a 12×6λ/D dark zone separated from the primary component of the simulated binary star (STF 3121 AB) by 4λ/D. This contrast is better by a factor of 13.2 than the contrast floor reached by standard single-star wavefront control (SSWC). We also discuss the main limiting factors that affect the MSWC performance in our experiments.

Binary stars↗
NASA NTRS1989

Fluid/Gas Process Controller

Fluid/gas controller, or "Super Burper", developed to obtain precise fill quantities of working fluid and noncondensable gas in heat pipe by incorporating detachable external reservoir into system during processing stage. Heat pipe filled with precise quantities of working fluid and noncondensable gas, and procedure controlled accurately. Application of device best suited for high-quality, high performance heat pipes. Device successfully implemented with various types of heat pipes, including vapor chambers, thermal diodes, large space radiators, and sideflows.

Ramos, Sergio↗
NASA NTRS1991

High-power converters for space applications

Phase 1 was a concept definition effort to extend space-type dc/dc converter technology to the megawatt level with a weight of less than 0.1 kg/kW (220 lb./MW). Two system designs were evaluated in Phase 1. Each design operates from a 5 kV stacked fuel cell source and provides a voltage step-up to 100 kV at 10 A for charging capacitors (100 pps at a duty cycle of 17 min on, 17 min off). Both designs use an MCT-based, full-bridge inverter, gaseous hydrogen cooling, and crowbar fault protection. The GE-CRD system uses an advanced high-voltage transformer/rectifier filter is series with a resonant tank circuit, driven by an inverter operating at 20 to 50 kHz. Output voltage is controlled through frequency and phase shift control. Fast transient response and stability is ensured via optimal control. Super-resonant operation employing MCTs provides the advantages of lossless snubbing, no turn-on switching loss, use of medium-speed diodes, and intrinsic current limiting under load-fault conditions. Estimated weight of the GE-CRD system is 88 kg (1.5 cu ft.). Efficiency of 94.4 percent and total system loss is 55.711 kW operating at 1 MW load power. The Maxwell system is based on a resonance transformer approach using a cascade of five LC resonant sections at 100 kHz. The 5 kV bus is converted to a square wave, stepped-up to a 100 kV sine wave by the LC sections, rectified, and filtered. Output voltage is controlled with a special series regulator circuit. Estimated weight of the Maxwell system is 83.8 kg (4.0 cu ft.). Efficiency is 87.2 percent and total system loss is 146.411 kW operating at 1 MW load power.

Park, J. N.↗