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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 OSTI2015

HEARTBEAT STARS: SPECTROSCOPIC ORBITAL SOLUTIONS FOR SIX ECCENTRIC BINARY SYSTEMS

We present multi-epoch spectroscopy of “heartbeat stars,” eccentric binaries with dynamic tidal distortions and tidally induced pulsations originally discovered with the Kepler satellite. Optical spectra of six known heartbeat stars using the Wyoming Infrared Observatory 2.3 m telescope allow measurement of stellar effective temperatures and radial velocities from which we determine orbital parameters including the periods, eccentricities, approximate mass ratios, and component masses. These spectroscopic solutions confirm that the stars are members of eccentric binary systems with eccentricities e > 0.34 and periods P = 7–20 days, strengthening conclusions from prior works that utilized purely photometric methods. Heartbeat stars in this sample have A- or F-type primary components. Constraints on orbital inclinations indicate that four of the six systems have minimum mass ratios q = 0.3–0.5, implying that most secondaries are probable M dwarfs or earlier. One system is an eclipsing, double-lined spectroscopic binary with roughly equal-mass mid-A components (q = 0.95), while another shows double-lined behavior only near periastron, indicating that the F0V primary has a G1V secondary (q = 0.65). This work constitutes the first measurements of the masses of secondaries in a statistical sample of heartbeat stars. The good agreement between our spectroscopic orbital elements and those derived using a photometric model support the idea that photometric data are sufficient to derive reliable orbital parameters for heartbeat stars.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Heartbeat: Detecting Malware by Periodic Power Signal Injection and Monitoring

Rootkits and other stealthy malware attempt to conceal their presence on a computer by making changes to the host computer’s operating environment. ORNL’s Heartbeat technology detects these changes, and thus the malware itself. Heartbeat operates by directly monitoring the DC power consumption of the computer while a set of operations, the “heartbeat,” is executed periodically. These operations exercise parts of the operating system that are common targets of malware tampering. The power consumption during these heartbeat events is monitored and then compared to a previously learned baseline, with any significant deviation detected and analyzed. This technology has been tested and validated in a laboratory environment, and ORNL is currently seeking a deployment partner to allow for further in-context development and testing of this technology.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

2018 Technology Innovation Program Heartbeat

Heartbeat responds to this problem by focusing instead on the physical behavior of the device being protected, under the hypothesis that malware infection will produce a measurable change in the power consumption state of a device that can be picked up by an outside detector. All code execution uses power, so the execution of malware—especially polymorphic variants—will leave a trace on a power consumption record. The Heartbeat system collects power trace measurements directly from the hardware and so is invisible to malware and resilient to internet service interruption. By collecting power measurement data only during the periodic invocation of a single or of several system functions, Heartbeat will address several challenges that plague current anomaly-based intrusion detection systems and is operational-context agnostic.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

RADIAL VELOCITY MONITORING OF KEPLER HEARTBEAT STARS

Heartbeat stars (HB stars) are a class of eccentric binary stars with close periastron passages. The characteristic photometric HB signal evident in their light curves is produced by a combination of tidal distortion, heating, and Doppler boosting near orbital periastron. Many HB stars continue to oscillate after periastron and along the entire orbit, indicative of the tidal excitation of oscillation modes within one or both stars. These systems are among the most eccentric binaries known, and they constitute astrophysical laboratories for the study of tidal effects. We have undertaken a radial velocity (RV) monitoring campaign of Kepler HB stars in order to measure their orbits. We present our first results here, including a sample of 22 Kepler HB systems, where for 19 of them we obtained the Keplerian orbit and for 3 other systems we did not detect a statistically significant RV variability. Results presented here are based on 218 spectra obtained with the Keck/HIRES spectrograph during the 2015 Kepler observing season, and they have allowed us to obtain the largest sample of HB stars with orbits measured using a single instrument, which roughly doubles the number of HB stars with an RV measured orbit. The 19 systems measured here have orbital periods from 7 to 90 days and eccentricities from 0.2 to 0.9. We show that HB stars draw the upper envelope of the eccentricity–period distribution. Therefore, HB stars likely represent a population of stars currently undergoing high eccentricity migration via tidal orbital circularization, and they will allow for new tests of high eccentricity migration theories.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

The universal “heartbeat” oscillations in black hole systems across the mass-scale

The hyperluminous X-ray source (HLX-1, peak X-ray luminosity ∼10{sup 42} erg s{sup −1}) near the spiral galaxy ESO 243-49, which underwent recurrent outbursts within a period of ∼400 days, is possibly the best candidate for an intermediate mass black hole (IMBH). The physical reason for this quasiperiodic variability is still unclear. We explore the possibility of radiation-pressure instability in the accretion disk by modeling the light curve of HLX-1, and find that it can roughly reproduce the duration, period, and amplitude of the recurrent outbursts in HLX-1 with an IMBH of ∼10{sup 5} M{sub ⊙}. Our result provides a possible mechanism to explain the recurrent outbursts in HLX-1. We further find a universal correlation between the outburst duration and the bolometric luminosity for the black hole (BH) sources with a very broad mass range (e.g., X-ray binaries, HLX-1, and active galactic nuclei), which is roughly consistent with the prediction of radiation-pressure instability of the accretion disk. These results imply that “heartbeat” oscillations triggered by radiation-pressure instability may appear in different-scale BH systems.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Heartbeat Malware Detection

Legacy signature or heuristics-based solutions for malware infections and cyber-attacks are unable to keep up with the flood of new polymorphic malware samples, or to address the powerful and stealthy tactics of kernel-level rootkits. Heartbeat responds to this problem by focusing instead on the physical behavior of the device being protected, under the hypothesis that malware infection will produce a measurable change in the power consumption state of a device that can be picked up by an outside detector.

Dawson, Joel A↗
DOE OSTI2026

The Heartbeat of PIP-II

Presenting a bird eye's view of the reference line project in the radio frequency department for the IGNITE OFF competition.

Subedi, Harsheet [Unlisted, US; Fermilab] (ORCID:0↗
DOE OSTI2019

The Telltale Heartbeat: Detection and Characterization of Eccentric Orbiting Planets via Tides on Their Host Star

We present an analytic description of tides raised on a star by a small orbiting body. In particular, we highlight the disproportionate effect of eccentricity and thus the scope for using these tides to detect and characterize the orbits of exoplanets and brown dwarfs. The tidal distortions of the star produced by an eccentric orbit are, in comparison to a circular orbit, much richer in detail and potentially visible from any viewing angle. The magnitude of these variations is much larger than that in a circular orbit of the same semimajor axis. These variations are visible in both photometric and spectroscopic data and dominate other regular sources of phase variability (e.g., reflection and Doppler beaming) over a particularly interesting portion of parameter space. These tidal signatures will be a useful tool for planet detection on their own and, used in concert with other methods, provide powerful constraints on planetary and stellar properties.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

DISK–WIND CONNECTION DURING THE HEARTBEATS OF GRS 1915+105

Disk and wind signatures are seen in the soft state of Galactic black holes, while the jet is seen in the hard state. Here we study the disk–wind connection in the ρ class of variability in GRS 1915+105 using a joint NuSTAR – Chandra observation. The source shows 50 s limit cycle oscillations. By including new information provided by the reflection spectrum and using phase-resolved spectroscopy, we find that the change in the inner disk inferred from the blackbody emission is not matched by reflection measurements. The latter is almost constant, independent of the continuum model. The two radii are comparable only if the disk temperature color correction factor changes, an effect that could be due to the changing opacity of the disk caused by changes in metal abundances. The disk inclination is similar to that inferred from the jet axis, and oscillates by ∼10°. The simultaneous Chandra data show the presence of two wind components with velocities between 500 and 5000 km s{sup −1}, and possibly two more with velocities reaching 20,000 km s{sup −1} (∼0.06 c ). The column densities are ∼5 × 10{sup 22} cm{sup −2}. An upper limit to the wind response time of 2 s is measured, implying a launch radius of <6 × 10{sup 10} cm. The changes in wind velocity and absorbed flux require the geometry of the wind to change during the oscillations, constraining the wind to be launched from a distance of 290–1300 r{sub g} from the black hole. Both data sets support fundamental model predictions in which a bulge originates in the inner disk and moves outward as the instability progresses.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

The Pseudosynchronization of Binary Stars Undergoing Strong Tidal Interactions

Eccentric binaries known as heartbeat stars experience strong dynamical tides as the stars pass through periastron, providing a laboratory to study tidal interactions. We measure the rotation periods of 24 heartbeat systems, using the Kepler light curves to identify rotation peaks in the Fourier transform. Where possible, we compare the rotation period to the pseudosynchronization period derived by Hut. Few of our heartbeat stars are pseudosynchronized with the orbital period. For four systems, we were able to identify two sets of rotation peaks, which we interpret as the rotation from both stars in the binary. Most stars in our sample have rotation rates larger than the pseudosynchronization period while a single target rotates much faster than this rate. The majority of the systems have a rotation period that is approximately (3/2) times the pseudosynchronization period, suggesting that other physical mechanisms strongly influence the star’s evolution.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

MetaHeart: Metasurface enabled biometrics camouflage

Privacy-invading biometrics monitoring is becoming a prominent security threat as modern sensing systems move to higher operating frequencies (mmWave, sub-THz), increasing sensing resolution and accuracy. As such, developing systems that can protect or obfuscate biometrics from adversarial intrusion becomes pivotal to preserving user privacy. In this work, we develop and implement MetaHeart, a real-time biometrics misinformation system based on reflective, programmable metasurfaces and dynamic phase-front manipulation of radar inferences. MetaHeart’s key goal is to prevent the leakage of a legitimate user’s heartbeat biometrics by spoofing fake heartbeat signals at a malicious, radar-equipped, heart rate sensing intruder. Furthermore, we experimentally demonstrate MetaHeart’s ability to fake Alice’s presence when she is not there and to fool Trudy’s inferences even when Alice is present, achieving an overall accuracy above 98%. Finally, we conduct a robustness analysis to determine MetaHeart’s required spatial placement within the intruder’s monitoring area that would allow for effective spoofing.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

Ioss IO Subsystem

The Ioss is a database-independent package for providing an object-oriented, abstract interface to IO capabilities for a finite element application; and concrete database interfaces which provided input and/or output to exodusII, xdmf, generated, and heartbeat database formats. The Ioss provides an object-oriented C++-based IO interface for a finite element application code. The application code can perform all IO operations through the Ioss interface which is typically at a higher abstraction level than the concrete database formats. The Ioss then performs the needed operations to translate the finite element data to the specific format required by the concrete database implementations. The Ioss currently supports interfaces to exodusII, xdmf, generated, and heartbeat formats, but additional formats can be easily added.

Sjaardema, Gregory↗
DOE OSTI2019

Design of Fluxgate Sensors for Different Applications from Geology to Medicine

In this study, we have shown that fluxgate sensors can be used for different application areas. Alternative sensor configurations have been developed for three different application areas. These are mainly rod- and ring-type fluxgate sensors. In the first study, a measurement system with the rod-type fluxgate sensor has been developed in order to monitor the local magnetic field distributions on a magnetic tape (e.g., credit card). With this system, the magnetic recording data on the credit card were measured and imaged successfully. The second and the third application areas, which are monitoring the influence of solar storms on the earth field and heartbeat analysis of mankind, were carried out by using a ring-core fluxgate sensor geometry.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Hybrid printing of wearable piezoelectric sensors

Piezoelectricity provides an ideal electromechanical mechanism with emerging applications in wearable devices due to its simplicity and self-powered nature. However, the 3D printing of piezoelectric devices still faces many challenges, including material printability, high energy poling process, and low dimensional accuracy. This study demonstrates, for the first time, a tellurium nanowire-based piezoelectric device fabricated by a hybrid printing method integrating highly complementary aerosol jet printing and extrusion printing in a single printing platform. The aerosol-jet-printed tellurium nanowire demonstrates piezoelectric properties without the need for any poling processing due to the unique properties of the tellurium nanowires. The silver nanowire electrodes printed by aerosol jet printing demonstrate excellent conductivity and stretchability without the need for sintering. An extrusion method is employed to print the silicone films, which serve as the stretchable substrate and the electrical insulation layers between the printed tellurium and silver. The printed wearable piezoelectric devices were attached to a human wrist to detect different hand gestures and to a human neck to detect heartbeat without using an external power source. In conclusion, the fully printed, sintering-free and poling-free, and stretchable piezoelectric device opens enormous opportunities for facile integration with a broad range of printed electronics and wearable devices.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

Differences in toxicity of anionic and cationic PAMAM and PPI dendrimers in zebrafish embryos and cancer cell lines

Dendrimers are an emerging class of polymeric nanoparticles with beneficial biomedical applications like early diagnostics, in vitro gene transfection or controlled drug delivery. However, the potential toxic impact of exposure on human health or the environment is often inadequately defined. Thus, polyamidoamine (PAMAM) dendrimers of generations G3.0, 3.5, 4.0, 4.5 and 5.0 and polypropylenimine (PPI) dendrimers G3.0, 4.0 and 5.0 were tested in zebrafish embryos for 96 h and human cancer cell lines for 24 h, to assess and compare developmental in vivo toxicity with cytotoxicity. The zebrafish embryo toxicity of cationic PAMAM and PPI dendrimers increased over time, with EC50 values ranging from 0.16 to just below 1.7 μM at 24 and 48 hpf. The predominant effects were mortality, plus reduced heartbeat and blood circulation for PPI dendrimers. Apoptosis in the embryos increased in line with the general toxicity concentration-dependently. Hatch and dechorionation of the embryos increased the toxicity, suggesting a protective role of the chorion. Lower generation dendrimers were more toxic in the embryos whereas the toxicity in the HepG2 and DU145 cell lines increased with increasing generation of cationic PAMAMs and PPI dendrimers. HepG2 were less sensitive than DU145 cells, with IC50 values ≥ 402 μM (PAMAMs) and ≤ 240 μM (PPIs) for HepG2 and ≤ 13.24 μM (PAMAMs) and ≤ 12.84 μM (PPIs) for DU145. Neither in fish embryos nor cells toxicity thresholds were determinable for anionic PAMAM G3.5 and G4.5. The study demonstrated that the cytotoxicity underestimated the in-vivo toxicity of the dendrimers in the fish embryos. - Highlights: • Zebrafish embryo toxicity of cationic PAMAM and PPI dendrimers increased over time. • Zebrafish embryo toxicity of cationic dendrimers did not increase with generation. • Cationic dendrimers induced apoptosis in zebrafish embryos. • Toxicity of cationic dendrimers was lower in HepG2 and DU145 than zebrafish embryos. • Anionic PAMAM dendrimers showed little to no toxicity in fish embryos and cells.

60 APPLIED LIFE SCIENCES↗