SEARCH · Engineering Papers
Results for “Twinning”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Large-Scale V/STOL Experimental Investigations of an Ejector-Lift Fighter and a Twin Tilt-Nacelle Transport
In the 1980s NASA Aeronautics was actively involved in full-scale wind tunnel testing of promising VSTOL aircraft concepts. This presentation looks at two, a multi-role fighter and a subsonic tactical transport. Their strengths and weaknesses are discussed with some of the rationale that ultimately led to the selection of competing concepts for production, namely the V-22 Osprey and the F-35 Lightning. The E7-A STOVL multi-role fighter was the product of an aircraft development program in the late 1980s by NASA, the Defense Advanced Research Projects Agency (DARPA), the Canadian Department of Industry Science and Technology (DIST), and industry partners General Dynamics and Boeing Dehavilland. The program was conducted an in response to increasing US-UK interest in supersonic STOVL fighters. The objective was to design an aircraft that could replace most existing close air support-air combat fighters with a single aircraft that had some of the qualities of an air superiority fighter and the deployment flexibility of a VSTOL aircraft. The resulting E7-A concept was a delta-wing supersonic fighter that used a fuselage-mounted thrust augmenting ejector and a ventral deflecting jet nozzle for vertical lift. The Grumman Aircraft Company, the Navy, and NASA developed the Design-698 (D-698) subsonic tactical transport in response to the Navy's Type A VSTOL utility aircraft requirement. The objective was to develop a subsonic utility transport with the operational flexibility of a helicopter, but with greater speed and range. The D-698 employs two high-bypass turbofan engines mounted on a dumbbell that rotates through ninety degrees for vertical takeoff and cruise flight. Movable vanes positioned in the exhaust flow provide control in hover with the need for reaction control jets. The presentations concluding comments suggest that technology advances in the last thirty-years may justify the value of revisiting some of these concepts.
Novel High Temperature Capacitive Pressure Sensor Utilizing SiC Integrated Circuit Twin Ring Oscillators
This paper describes initial development and testing of a novel high temperature capacitive pressure sensor system. The pressure sensor system consists of two 4H-SiC 11-stage ring oscillators and a SiCN capacitive pressure sensor. One oscillator has the capacitive pressure sensor fixed at one node in its feedback loop and varies as a function of pressure and temperature while the other provides a pressure-independent reference frequency which can be used to temperature compensate the output of the first oscillator. A two-day repeatability test was performed up to 500C on the oscillators and the oscillator fundamental frequency changed by only 1. The SiCN capacitive pressure sensor was characterized at room temperature from 0 to 300 psi. The sensor had an initial capacitance of 3.76 pF at 0 psi and 1.75 pF at 300 psi corresponding to a 54 change in capacitance. The integrated pressure sensor system was characterized from 0 to 300 psi in steps of 50 psi over a temperature range of 25 to 500C. The pressure sensor system sensitivity was 0.113 kHzpsi at 25C and 0.026 kHzpsi at 500C.
Twin Target Thrust Reverser Module
A nozzle assembly for a dual gas turbine engine propulsion system includes a housing mountable proximate to a first bypass passage of a first gas turbine engine and a second bypass passage of a second gas turbine engine, first and second upper doors, and first and second lower doors. Each of the first and second upper doors and the first and second lower doors are pivotally mounted to the housing for movement between a stowed position and a deployed position in which airflow through the first and second bypass passages is redirected relative to respective centerline axes of the first and second gas turbine engines.
A Giant Impact as the Likely Origin of Different Twins in the Kepler-107 Exoplanet System
Measures of exoplanet bulk densities indicate that small exoplanets with radius less than 3 Earth radii (R(sub ⊕)) range from low-density sub-Neptunes containing volatile elements to higher-density rocky planets with Earth-like or iron-rich (Mercury-like) compositions. Such astonishing diversity in observed small exoplanet compositions may be the product of different initial conditions of the planet-formation process or different evolutionary paths that altered the planetary properties after formation. Planet evolution may be especially affected by either photoevaporative mass loss induced by high stellar X-ray and extreme ultraviolet (XUV) flux or giant impacts. Although there is some evidence for the former, there are no unambiguous findings so far about the occurrence of giant impacts in an exoplanet system. Here, we characterize the two innermost planets of the compact and near-resonant system Kepler-107 (ref. 9). We show that they have nearly identical radii (about 1.5–1.6R(sub ⊕)), but the outer planet Kepler-107 c is more than twice as dense (about 12.6 g cm–3) as the innermost Kepler-107 b (about 5.3 g cm−3). In consequence, Kepler-107 c must have a larger iron core fraction than Kepler-107 b. This imbalance cannot be explained by the stellar XUV irradiation, which would conversely make the more-irradiated and less-massive planet Kepler-107 b denser than Kepler-107 c. Instead, the dissimilar densities are consistent with a giant impact event on Kepler-107 c that would have stripped off part of its silicate mantle. This hypothesis is supported by theoretical predictions from collisional mantle stripping, which match the mass and radius of Kepler-107 c.
Twin Telescope Tests: Assessing Station Oriented Systematic Errors
Each of NASA’s three Deep Space Network sites has multiple large antennas capable of acquiring VLBI data. The long range plan is to have four 34-meter beam waveguide antennas at each site. At present Goldstone has three, Canberra has three, and Madrid has two with two more under construction. These antennas offer the opportunity to do connected element interferometry (CEI) over the few hundred meter baselines within each complex. Given that all antennas within a site are of nominally the same structural design, are run off the same clock, observe through almost the same atmosphere, and are subject to almost the same geophysics, doing CEI experiments is an excellent way to probe the limits of VLBI accuracy and expose station-specific systematic errors. This paper will report the results of just such tests which achieved about 0.2 mm baseline precision per pass. Some stations exhibit more than 1 mm systematics. Based on this data we will discuss the implications for whether the IAG’s goal of 1 mm station stability in VLBI geodesy is possible for large antennas.
Agriculture's Historic Twin-Challenge Toward Sustainable Water Use and Food Supply for All
A sustainable and just future, envisioned by the UN's 2030 Agenda for Sustainable Development, puts agricultural systems under a heavy strain. The century-old quandary to provide ever-growing human populations with sufficient food takes on a new dimension with the recognition of environmental limits for agricultural resource use. To highlight challenges and opportunities toward sustainable food security in the twenty first century, this perspective paper provides a historical account of the escalating pressures on agriculture and freshwater resources alike, supported by new quantitative estimates of the ascent of excessive human water use. As the transformation of global farming into sustainable forms is unattainable without a revolution in agricultural water use, water saving and food production potentials are put into perspective with targets outlined by the Sustainable Development Goals (SDGs). The literature body and here-confirmed global estimates of untapped opportunities in farm water management indicate that these measures could sustainably intensify today's farming systems at scale. While rigorous implementation of sustainable water withdrawals (SDG 6.4) might impinge upon 5% of global food production, scaling-up water interventions in rainfed and irrigated systems could over-compensate such losses and further increase global production by 30% compared to the current situation (SDG 2.3). Without relying on future technological fixes, traditional on-farm water and soil management provides key strategies associated with important synergies that needs better integration into agro-ecological landscape approaches. Integrated strategies for sustainable intensification of agriculture within planetary boundaries are a potential way to attain several SDGs, but they are not yet receiving attention from high-level development policies.
KELT-23Ab: A Hot Jupiter Transiting a Near-solar Twin Close to the TESS and JWST Continuous Viewing Zones
We announce the discovery of KELT-23Ab, a hot Jupiter transiting the relatively bright(V = 10.3) star BD+66911(TYC 4187-996-1), and characterize the system using follow-up photometry and spectroscopy. A global fit to the system yields host-star properties of= T5900 49effK,=-+MM0.9450.0540.060*, = RR0.995 0.015*, =-+LL1.0820.0480.051*, =-+ glog 4.4180.0250.026 (cgs), and=- Fe H0.105 0.077. KELT-23Ab is a hot Jupiter with a mass of= -+ MM0.938P0.0420.045J, radius of = RR1.322 0.025PJ, and density of r=-+ 0.504P0.0350.038gcm − 3. Intense insolation flux from the star has likely caused KELT-23Ab to become inflated. The time of inferior conjunction is=T2458149.40776=0.00091 BJD0TDB and the orbital period is=-+P2.2553530.0000300.000031days. There is strong evidence that KELT-23A is a member of a long-period binary star system with a less luminous companion, and due to tidal interactions, the planet is likely to spiral into its host within roughly a gig a year. This system has one of the highest positive ecliptic latitudes of all transiting planet hosts known to date, placing it near the Transiting Planet Survey Satellite and James Webb Space Telescope continuous viewing zones. Thus we expect it to be an excellent candidate for long-term monitoring and follow up with these facilities.
Digital Twin for Quality and Mechanical Systems Assurance
Explore the source record for details and available documents.
TESS-Keck Survey. V. Twin Sub-Neptunes Transiting the Nearby G Star HD 63935
We present the discovery of two nearly identically sized sub-Neptune transiting planets orbiting HD 63935, abright(V=8.6 mag), Sun-like(Teff=5560 K)star at 49 pc. TESS identified thefirst planet, HD 63935 b(TOI-509.01), in Sectors 7 and 34. We identified the second signal(HD 63935 c)in Keck High Resolution EchelleSpectrometer and Lick Automated Planet Finder radial velocity data as part of our follow-up campaign. It wassubsequently confirmed with TESS photometry in Sector 34 as TOI-509.02. Our analysis of the photometric andradial velocity data yielded a robust detection of both planets with periods of 9.0600±0.007 and 21.40±0.0019days, radii of 2.99±0.14 and 2.90±0.13R⊕, and masses of 10.8±1.8 and 11.1±2.4M⊕. We calculated densities for planets b and c consistent with a few percent of the planet mass in hydrogen/helium envelopes. Wealso describe our survey’s efforts to choose the best targets for James Webb Space Telescope atmospheric follow-up. These efforts suggest that HD 63935 b has the most clearly visible atmosphere of its class. It is the best targetfor transmission spectroscopy(ranked by the transmission spectroscopy metric, a proxy for atmosphericobservability)in the so far uncharacterized parameter space comprising sub-Neptune-sized(2.6R⊕<Rp<4R⊕),moderately irradiated(100F⊕<Fp<1000F⊕)planets around G stars. Planet c is also a viable target fortransmission spectroscopy, and given the indistinguishable masses and radii of the two planets, the system servesas a natural laboratory for examining the processes that shape the evolution of sub-Neptune planets.
Digital Twins- An Imitation of Life
Explore the source record for details and available documents.
Digital Twins – An Imitation of Life
Explore the source record for details and available documents.
Using fmdtools Models as Low-fidelity Digital Twins for Operations Support and In-time Decision Making
Explore the source record for details and available documents.
Powering Digital Transformation with Digital Twin: A NASA Perspective
Explore the source record for details and available documents.