SEARCH · Search NASA

Results for “Turning”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7

All sources NASA NTRS DOE OSTI

NASA NTRS2003

Coordinated turn-and-reach movements. I. Anticipatory compensation for self-generated coriolis and interaction torques

When reaching movements involve simultaneous trunk rotation, additional interaction torques are generated on the arm that are absent when the trunk is stable. To explore whether the CNS compensates for such self-generated interaction torques, we recorded hand trajectories in reaching tasks involving various amplitudes and velocities of arm extension and trunk rotation. Subjects pointed to three targets on a surface slightly above waist level. Two of the target locations were chosen so that a similar arm configuration relative to the trunk would be required for reaching to them, one of these targets requiring substantial trunk rotation, the other very little. Significant trunk rotation was necessary to reach the third target, but the arm's radial distance to the body remained virtually unchanged. Subjects reached at two speeds-a natural pace (slow) and rapidly (fast)-under normal lighting and in total darkness. Trunk angular velocity and finger velocity relative to the trunk were higher in the fast conditions but were not affected by the presence or absence of vision. Peak trunk velocity increased with increasing trunk rotation up to a maximum of 200 degrees /s. In slow movements, peak finger velocity relative to the trunk was smaller when trunk rotation was necessary to reach the targets. In fast movements, peak finger velocity was approximately 1.7 m/s for all targets. Finger trajectories were more curved when reaching movements involved substantial trunk rotation; however, the terminal errors and the maximal deviation of the trajectory from a straight line were comparable in slow and fast movements. This pattern indicates that the larger Coriolis, centripetal, and inertial interaction torques generated during rapid reaches were compensated by additional joint torques. Trajectory characteristics did not vary with the presence or absence of vision, indicating that visual feedback was unnecessary for anticipatory compensations. In all reaches involving trunk rotation, the finger movement generally occurred entirely during the trunk movement, indicating that the CNS did not minimize Coriolis forces incumbent on trunk rotation by sequencing the arm and trunk motions into a turn followed by a reach. A simplified model of the arm/trunk system revealed that additional interaction torques generated on the arm during voluntary turning and reaching were equivalent to < or =1.8 g (1 g = 9.81 m/s(2)) of external force at the elbow but did not degrade performance. In slow-rotation room studies involving reaching movements during passive rotation, Coriolis forces as small as 0.2 g greatly deflect movement trajectories and endpoints. We conclude that compensatory motor innervations are engaged in a predictive fashion to counteract impending self-generated interaction torques during voluntary reaching movements.

NASA Discipline Neuroscience↗

NASA NTRS2004

Eruption of a Multiple-Turn Helical Magnetic Flux Tube in a Large Flare: Evidence for External and Internal Reconnection that Fits the Breakout Model of Solar Magnetic Eruptions

We present observations and an interpretation of a unique multiple-turn spiral flux tube eruption from active region 10030 on 2002 July 15. The TRACE C IV observations clearly show a flux tube that is helical and erupting from within a sheared magnetic field. These observations are interpreted in the context of the breakout model for magnetic field explosions. The initiation of the helix eruption. as determined by a linear backward extrapolation, starts 25 s after the peak of the flare's strongest impulsive spike of microwave gyrosynchrotron radiation early in the flare s explosive phase, implying that the sheared core field is not the site of the initial reconnection. Within the quadrupolar configuration of the active region, the external and internal reconnection sites are identified in each of two consecutive eruptive flares that produce a double coronal mass ejection (CME). The first external breakout reconnection apparently releases an underlying sheared core field and allows it to erupt, leading to internal reconnection in the wake of the erupting helix. This internal reconnection releases the helix and heats the two-ribbon flare. These events lead to the first CME and are followed by a second breakout that initiates a second and larger halo CME. The strong magnetic shear in the region is compatible with the observed rapid proper motion and evolution of the active region. The multiple-turn helix originates from above a sheared-field magnetic inversion line within a filament channel. and starts to erupt only after fast breakout reconnection has started. These observations are counter to the standard flare model and support the breakout model for eruptive flare initiation.

Gary, G. Allen↗

NASA NTRS2010

Rapid Turn Around BRIC-PDFU Payload: A New Paradigm for Spaceflight Experiments

In 2009, NASA's Fundamental Space Biology program provided an opportunity for investigators to propose for a quick-turn-around multi-user spaceflight experiment that focused on the model plant species Arabidopsis thaliana. This was a passive payload with no on-orbit power or communications available. An NRA was rapidly written (8/09), released (NNH09ZTT004N; 9/09), proposals were received (11/09) and peer reviewed with 3 PI groups selected for flight (1/10): (1) A-L Paul, University of Florida, (2) E. Blancaflor, Noble Foundation, (3) J. Kiss, Miami University. The investigators flew Arabidopsis seeds or callus cultures of their choosing (plated onto 60 mm diameter Petri dishes containing agarsolidified media) on the STS-131 Space Shuttle mission (launched 4/5/10) and the resulting plant tissues returned to earth on 4/20/10. Each petri dish was placed inside its own Petri Dish Fixation Unit (PDFU), which was assembled and loaded with either formaldehyde, glutaraldehyde or RNAlater for crew-facilitated on-orbit fixation. Five PDFUs plus a temperature data logger were loaded into each of 8 BRIC-PDFUs (Biological Research In Canisters PDFU). All eight BRIC-PDFUs were loaded into a half tray along with actuator equipment that the crew used for the fixations. Pre-flight turn-over was 28 hours prior to launch. The BRIC-PDFU assemblies were removed from the orbiter and handed over to the investigator teams for processing 5-6 hours after landing. This payload demonstrated a rapid response turnaround for flying multiple peer-reviewed science investigations using previously flown hardware and minimal ISS-resources. The approach used reduced both hardware/certification and PI costs. The time waiting for a flight opportunity for the selected Pls was minimal. This new paradigm for spaceflight experiments may provide a model for future flight research opportunities. The ultimate goal is to fly as many investigators as rapidly as possible and reinvigorate the space biology community while obtaining high-quality, peer-reviewed science.

Levine, Howard G.↗

NASA NTRS2013

A Turn-Projected State-Based Conflict Resolution Algorithm

State-based conflict detection and resolution (CD&R) algorithms detect conflicts and resolve them on the basis on current state information without the use of additional intent information from aircraft flight plans. Therefore, the prediction of the trajectory of aircraft is based solely upon the position and velocity vectors of the traffic aircraft. Most CD&R algorithms project the traffic state using only the current state vectors. However, the past state vectors can be used to make a better prediction of the future trajectory of the traffic aircraft. This paper explores the idea of using past state vectors to detect traffic turns and resolve conflicts caused by these turns using a non-linear projection of the traffic state. A new algorithm based on this idea is presented and validated using a fast-time simulator developed for this study.

Butler, Ricky W.↗

NASA NTRS2015

Inward-Turning Streamline-Traced Inlet Design Method for Low-Boom, Low-Drag Applications

A new design method for inward-turning, streamline-traced inlets is presented. Resulting designs are intended for moderate supersonic, low-drag, low-boom applications such as that required for NASA's proposed low-boom flight demonstration aircraft. A critical feature of these designs is the internal cowl lip angle that allows for little or no flow turning on the outer nacelle. Present methods using conical-flow Busemann parent flowfields have simply truncated, or otherwise modified the stream-traced contours to include this internal cowl angle. Such modifications disrupt the parent flowfield, reducing inlet performance and flow uniformity. The method presented herein merges a conical flowfield that includes a leading shock with a truncated Busemann flowfield in a manner that minimizes unwanted interactions. A leading internal cowl angle is now inherent in the parent flowfield, and inlet contours traced from this flowfield retain its high performance and good flow uniformity. CFD analysis of a candidate inlet design is presented that verifies the design technique, and reveals a starting issue with the basic geometry. A minor modification to the cowl lip region is shown to eliminate this phenomenon, thereby allowing starting and smooth transition to sub-critical operation as back-pressure is increased. An inlet critical-point total pressure recovery of 96 is achieved based on CFD results for a Mach 1.7 freestream design. Correction for boundary-layer displacement thickness, and sizing for a given engine airflow requirement are also discussed.

low sonic boom↗

NASA NTRS2017

iPTF Discovery of the Rapid "Turn-On" of a Luminous Quasar

We present a radio-quiet quasar at z = 0.237 discovered ''turning on'' by the intermediate Palomar Transient Factory (iPTF). The transient, iPTF 16bco, was detected by iPTF in the nucleus of a galaxy with an archival Sloan Digital Sky Survey spectrum with weak narrow-line emission characteristic of a low-ionization nuclear emission-line region (LINER). Our follow-up spectra show the dramatic appearance of broad Balmer lines and a power-law continuum characteristic of a luminous (L(sub bol) approx. equal 10(exp 45) erg/s) type 1 quasar 12 yr. later. Our photometric monitoring with PTF from 2009-2012 and serendipitous X-ray observations from the XMM-Newton Slew Survey in 2011 and 2015 constrain the change of state to have occurred less than 500 days before the iPTF detection. An enhanced broad H(alpha)/[O III] (lambda)5007 line ratio in the type 1 state relative to other changing-look quasars also is suggestive of the most rapid change of state yet observed in a quasar. We argue that the greater than 10 increase in Eddington ratio inferred from the brightening in UV and X-ray continuum flux is more likely due to an intrinsic change in the accretion rate of a preexisting accretion disk than an external mechanism such as variable obscuration, microlensing, or the tidal disruption of a star. However, further monitoring will be helpful in better constraining the mechanism driving this change of state. The rapid ''turn-on'' of the quasar is much shorter than the viscous infall timescale of an accretion disk and requires a disk instability that can develop around a approx. equal 10(exp 8)solar mass black hole on timescales less than 1 yr.

Gezari, S.↗

DOE OSTI2023

Turbomachine blade trailing edge cooling circuit with turn passage having set of obstructions

A turbomachine blade, and a coupon for a turbomachine blade, are disclosed. The blade may include an airfoil body having a pressure side and a suction side connected by a leading edge and a trailing edge, a coolant feed passage defined in the airfoil body, and a coolant reuse passage defined in the airfoil body. The blade may also include a first cooling circuit defined in the airfoil body. The first cooling circuit may include a rearward passage extending toward the trailing edge from and fluidly coupled to the coolant feed passage, and a radially spreading return passage extending away from the trailing edge toward and fluidly coupled to the coolant reuse passage. The cooling circuit may also include a radially extending turn passage coupling the rearward passage and the radially spreading return passage. A first set of obstructions may be positioned in the radially extending turn passage.

Dyson, Thomas Earl↗

NASA NTRS1922

Turn indicator

This report presents a study of an instrument that can warn the pilot of the turning of his airplane. This instrument must satisfy three conditions: 1) It must give useful indication immediately from take-off; 2) The indications must be instantaneous and require no exertion by the pilot; 3) The indicator must be sensitive only to changes of orientation in the horizontal plane. Different solutions are presented such as a gyroscope driven by the suction of a Venturi tube.

INSTRUMENTS - TURN INDICATORS↗

DOE OSTI2024

Seismic Bracing Development for the Moore 3 Diamond Turning Machine at Lawrence Livermore National Laboratory

To allow for on-site Potassium Dihydrogen Phosphate (KDP) crystal finishing capabilities, Lawrence Livermore National Laboratory (LLNL) acquired the Moore 3 diamond turning machine. Equipment such as the Moore 3 is required by LLNL to have adequate seismic bracing before permanent installation to reduce the risk of personnel injury or machine damage during an earthquake. The purpose of this project was to design a bracket that can withstand seismic forces induced by the machine without hindering function. To develop a solution, background research—including stakeholder identification, stakeholder interviews, and a literature survey—was conducted. Based on LLNL site and stakeholder requirements, several approaches were developed for bracing the Moore 3. Ideations were evaluated based on a weighted decision matrix and a final design strategy was selected. This design was an L-shaped weldment that featured provisions for four HILTI concrete anchors, three triangular gussets, and a steel construction.

42 ENGINEERING↗

NASA NTRS2011

Diamond Turned High Precision PIAA Optics and Four Mirror PIAA System for High Contrast Imaging of Exo-planets

Off-axis, high-sag PIAA optics for high contrast imaging present challenges in manufacturing and testing. With smaller form factors and consequently smaller surface deformations (< 80 microns), diamond turned fabrication of these mirrors becomes feasible. Though such a design reduces the system throughput, it still provides 2(lambda)D inner working angle. We report on the design, fabrication, measurements, and initial assessment of the novel PIAA optics in a coronagraph testbed. We also describe, for the first time, a four mirror PIAA coronagraph that relaxes apodizer requirements and significantly improves throughput while preserving the low-cost benefits.

coronagraphy↗

DOE OSTI2023

Dual-Responsive Turn-On T 1 Imaging-Guided Mild Photothermia for Precise Apoptotic Cancer Therapy

Apoptosis has gained increasing attention in cancer therapy as an intrinsic signaling pathway, which leads to minimal leakage of waste products from a dying cell to neighboring normal cells. Among various stimuli to trigger apoptosis, mild hyperthermia is attractive but confronts limitations of non-specific heating and acquired resistance from elevated expression of heat shock proteins. Here, a dual-stimulation activated turn-on T 1 imaging-based nanoparticulate system (DAS) is developed for mild photothermia (≈43 °C)-mediated precise apoptotic cancer therapy. In the DAS, a superparamagnetic quencher (ferroferric oxide nanoparticles, Fe 3 O 4 NPs) and a paramagnetic enhancer (Gd-DOTA complexes) are connected via the N6-methyladenine (m 6 A)-caged, Zn 2+ -dependent DNAzyme molecular device. The substrate strand of the DNAzyme contains one segment of Gd-DOTA complex-labeled sequence and another one of HSP70 antisense oligonucleotide. When the DAS is taken up by cancer cells, overexpressed fat mass and obesity-associated protein (FTO) specifically demethylates the m 6</-sup>A group, thereby activating DNAzymes to cleave the substrate strand and simultaneously releasing Gd-DOTA complex-labeled oligonucleotides. The restored T 1 signal from the liberated Gd-DOTA complexes lights up the tumor to guide the location and time of deploying 808 nm laser irradiation. Afterward, locally generated mild photothermia works in concert with HSP70 antisense oligonucleotides to promote apoptosis of tumor cells. This highly integrated design provides an alternative strategy for mild hyperthermia-mediated precise apoptotic cancer therapy.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2023

Turn‐on Circularly Polarized Luminescence in Chiral Indium Chlorides by 5s 2 Metal Centers

Abstract Introducing chirality into the metal‐halide hybrids has enabled many emerging properties including chiroptical activity, spin‐dependent transport, and ferroelectricity. However, most of the chiral metal‐halide hybrids to date are non‐emissive, and the underlying mechanism remains elusive. Here, we show a new strategy to turn on the circularly polarized luminescence (CPL) in chiral metal‐halide hybrids. We demonstrate that alloying Sb 3+ into chiral indium‐chloride hybrids dramatically increases the photoluminescence quantum yield in two new series of chiral indium‐antimony chlorides. These materials exhibit strong CPL signals with tunable energy and a high dissymmetry factor up to 1.5×10 −2 . Mechanistic studies reveal that the emission originates from the self‐trapped excitons centered in 5s 2 Sb 3+ . Moreover, near‐ultraviolet pumped white light is demonstrated with a polarization up to 6.0 %. Our work demonstrates new strategies towards highly luminescent chiral metal‐halide hybrids.

Wang, Zhiyu↗

DOE OSTI2022

Turn-on Circularly Polarized Luminescence in Chiral Indium Chlorides by 5s 2 Metal Centers

Introducing chirality into the metal-halide hybrids has enabled many emerging properties including chiroptical activity, spin-dependent transport, and ferroelectricity. However, most of the chiral metal-halide hybrids to date are non-emissive, and the underlying mechanism remains elusive. Here, in this study, we show a new strategy to turn on the circularly polarized luminescence (CPL) in chiral metal-halide hybrids. We demonstrate that alloying Sb 3+ into chiral indium-chloride hybrids dramatically increases the photoluminescence quantum yield in two new series of chiral indium-antimony chlorides. These materials exhibit strong CPL signals with tunable energy and a high dissymmetry factor up to 1.5×10 -2 . Mechanistic studies reveal that the emission originates from the self-trapped excitons centered in 5s 2 Sb 3+ . Moreover, near-ultraviolet pumped white light is demonstrated with a polarization up to 6.0 %. Our work demonstrates new strategies towards highly luminescent chiral metal-halide hybrids.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Time-resolved targeted metabolomics shows an abrupt switch from Calvin-Benson-Bassham cycle to tricarboxylic acid cycle when the light is turned off

Abstract In leaves, major CO₂ fluxes alternate between fixation by the Calvin-Benson-Bassham (CBB) cycle during light and release by the tricarboxylic acid (TCA) cycle in darkness. The speed at which leaf metabolism transitions between these pathways likely influences plant tolerance to fluctuating light conditions. To investigate these rapid metabolic shifts, we exposed leaves to ¹³CO₂ for 20 min to establish a quasi-steady state before abruptly turning off the light while maintaining ¹³CO₂ feeding. Within 10 s of dark transition, 3-phosphoglycerate levels rose significantly while most other CBB cycle intermediates decreased by more than 90%. Simultaneously, carbon accumulated in alanine, likely via pyruvate. Over the subsequent 10 min, six- and five-carbon TCA cycle intermediates steadily increased. In contrast, four-carbon TCA intermediates peaked at one minute, declined at three minutes, and rose again at 10 min, a pattern mirrored by most measured amino acids. These results reveal an exceptionally rapid metabolic reconfiguration from CO₂ fixation by the CBB cycle in light to TCA cycle activation for energy production in darkness, accompanied by substantial changes in amino acid metabolism.

Plant Sciences↗

DOE OSTI2025

Enhancing operational safety: The NSTX-U Shorted Turn Protection (STP) system

The NSTX-U Shorted Turn Protection (STP) system is a vital safety feature designed to protect the tokamak’s coils during operations. It employs a Kalman filter-based algorithm to monitor coil currents and detect faults in real-time. If an anomaly is detected, the system swiftly terminates the tokamak pulse to prevent damage. Developed with Matlab and Simulink, the STP system has been validated through real-time simulations, ensuring its effectiveness for the upcoming upgrades of the NSTX-U facility. In conclusion, this article presents the theory for implementation of the STP algorithm and the results from simulation and real-time implementation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2023

Efficient Bayesian inference with latent Hamiltonian neural networks in No-U-Turn Sampling

When sampling for Bayesian inference, one popular approach in the computational field is to use Hamiltonian Monte Carlo (HMC) and specifically the No-U-Turn Sampler (NUTS), which automatically decides the end time of the Hamiltonian trajectory. However, HMC and NUTS can require numerous numerical gradients of the target density and can prove slow in practice when relying on computationally expensive forward models. We propose Latent Hamiltonian neural networks (L-HNNs) with HMC and NUTS for solving Bayesian inference problems. Once trained, L-HNNs do not require numerical gradients of the target density during sampling, and hence numerous evaluations of the forward computational model. Moreover, L-HNNs satisfy important properties such as perfect time reversibility and Hamiltonian conservation, making them well-suited for use within HMC and NUTS because stationarity can be shown. We also propose the integration of L-HNNs in an online error monitoring scheme, in which numerical gradients of the target density are used for a few samples whenever the L-HNNs prediction errors are large. This online error monitor scheme prevents sample degeneracy in regions of low probability density and ensures robust uncertainty quantification. We demonstrate L-HNNs in NUTS with online error monitoring on several analytical examples involving complex, heavy-tailed, and high-local-curvature probability densities. We then demonstrate the applicability of L-HNNs in NUTS to two computational case studies, namely the Allen-Cahn stochastic partial differential equation and an elliptic partial differential equation with 25 and 50 inference parameters, respectively. Overall, the L-HNNs in NUTS with online error monitoring satisfactorily inferred these probability densities. In conclusion, compared to traditional NUTS, L-HNNs in NUTS with online error monitoring required 1–2 orders of magnitude fewer numerical gradients of the target density and improved the effective sample size (ESS) per gradient (which is a measure of both the sampling quality and the computational expense) by an order of magnitude.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2021

Turn-key constrained parameter space exploration for particle accelerators using Bayesian active learning

Abstract Particle accelerators are invaluable discovery engines in the chemical, biological and physical sciences. Characterization of the accelerated beam response to accelerator input parameters is often the first step when conducting accelerator-based experiments. Currently used techniques for characterization, such as grid-like parameter sampling scans, become impractical when extended to higher dimensional input spaces, when complicated measurement constraints are present, or prior information known about the beam response is scarce. Here in this work, we describe an adaptation of the popular Bayesian optimization algorithm, which enables a turn-key exploration of input parameter spaces. Our algorithm replaces the need for parameter scans while minimizing prior information needed about the measurement’s behavior and associated measurement constraints. We experimentally demonstrate that our algorithm autonomously conducts an adaptive, multi-parameter exploration of input parameter space, potentially orders of magnitude faster than conventional grid-like parameter scans, while making highly constrained, single-shot beam phase-space measurements and accounts for costs associated with changing input parameters. In addition to applications in accelerator-based scientific experiments, this algorithm addresses challenges shared by many scientific disciplines, and is thus applicable to autonomously conducting experiments over a broad range of research topics.

43 PARTICLE ACCELERATORS↗

DOE OSTI2023

Turning dead leaves into an active multifunctional material as evaporator, photocatalyst, and bioplastic

Large numbers of leaves fall on the earth each autumn. The current treatments of dead leaves mainly involve completely destroying the biocomponents, which causes considerable energy consumption and environmental issues. It remains a challenge to convert waste leaves into useful materials without breaking down their biocomponents. Here, we turn red maple dead leaves into an active three-component multifunctional material by exploiting the role of whewellite biomineral for binding lignin and cellulose. Owing to its intense optical absorption spanning the full solar spectrum and the heterogeneous architecture for effective charge separation, films of this material show high performance in solar water evaporation, photocatalytic hydrogen production, and photocatalytic degradation of antibiotics. Furthermore, it also acts as a bioplastic with high mechanical strength, high-temperature tolerance, and biodegradable features. These findings pave the way for the efficient utilization of waste biomass and innovations of advanced materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗