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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 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Demonstration of Intelligent HVAC Load Management With Deep Reinforcement Learning: Real-World Experience of Machine Learning in Demand Control

We report that buildings account for 40% of total primary energy consumption and 30% of all CO 2 emissions worldwide. A large portion of building energy consumption is due to heating, ventilation, and air-conditioning (HVAC) systems. In the summer, for example, more than 50% of a building’s electricity consumption is used for cooling. With proper energy management, buildings can provide load shifting, peak shaving, frequency regulation, and many other demand response services.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2025

Phenomenology of bubble size distributions in a first-order phase transition

In a cosmological first-order phase transition (FOPT), the true and false vacuum bubble radius distributions are not expected to be monochromatic, as is usually assumed. Consequently, Fermi balls (FBs) and primordial black holes (PBHs) produced in a dark FOPT will have extended mass distributions. We show how gravitational wave (GW), microlensing and Hawking evaporation signals for extended bubble radius/mass distributions deviate from the case of monochromatic distributions. The peak of the GW spectrum is shifted to lower frequencies, and the spectrum is broadened at frequencies below the peak frequency. Thus, the radius distribution of true vacuum bubbles introduces another uncertainty in the evaluation of the GW spectrum from a FOPT. The extragalactic gamma-ray signal at AMEGO-X/e-ASTROGAM from PBH evaporation may evince a break in the power-law spectrum between 5 MeV and 10 MeV for an extended PBH mass distribution. Optical microlensing surveys may observe PBH mass distributions with average masses below 10 -10 M ⊙ , which is not possible for monochromatic mass distributions. This expands the FOPT parameter space that can be explored with microlensing.

Marfatia, Danny [Univ. of Hawaii at Manoa, Honolul↗
DOE OSTI2022

High-speed silicon microresonator modulators with high optical modulation amplitude (OMA) at input powers >10 mW

A high-speed silicon photonic microdisc modulator is used with more than 10 mW optical power in the bus waveguide, extending the optical power handling regime used with compact silicon resonant modulators at 1550 nm. We present an experimental study of the wavelength tuning range and biasing path required to shift the resonant frequency to the optimal point versus on chip power. We measure the optical modulation amplitude (OMA) along different biasing trajectories of the microdisc under active modulation and demonstrate an OMA of 4.1 mW with 13.5 mW optical power in the bus waveguide at 20 Gbit/s non-return to zero (NRZ) data modulation.

Wang, Xiaoxi↗
DOE OSTI2020

Noncontact Flow Rate Using Laser Ultrasonics

Several types of advanced nuclear reactors are cooled with high-temperature liquid metal or molten salt flows. There is a critical need to measure flow velocity in flow channels for test purposes, and eventually in operational reactors. In conventional ultrasonic flow sensors, ultrasonic waves traveling in both the upstream and downstream directions are generated and detected by transducers that must contact the flow channels. A shift in the frequency or transit time between the two ultrasonic waves is measured to determine flow velocity. We describe here an initial effort to apply that sensing concept when the contact transducers are replaced by laser-based generation and detection instrumentation. This noncontact sensing avoids many practical problems associated with contact transducers when implemented on flow channels at high temperature. Laser-based flow monitoring can also be applied to hot-process piping in the geothermal energy, chemical-processing and petroleum-refining industries. Our effort has included theoretical simulation of noncontact laser-based flow monitoring, indicating capability of measuring flow velocities relevant to reactor cooling. It also included a room-temperature experimental demonstration using water as the flow liquid, and indicating capability of measuring flow velocity at a responsivity roughly consistent with simulation predictions. Plans were made for an experimental demonstration at Oregon State University using liquid metal at 110 degrees C.

02 PETROLEUM↗
DOE OSTI2025

Exploring transport-enabled gates with integrated optical addressing to demonstrate high fidelity control of trapped ion qubits in a scalable quantum computer

In recent years, experiments involving micofabricated surface ion traps have grown in complexity, and as this complexity grows, a common design has emerged in the form of quantum charge-coupled device architecture. This architecture, already utilized on multiple systems, supports multiple zones on a device for areas such as memory or computation. The shutting process between these zones is a process often seen to be minimized. An additional component to scalable surface trapped-ion experiments includes some form of integrated photonics, as free space lasers have difficulty scaling to many ions. Here, we discuss recent results in utilizing the shuttling process with integrated photonics to perform a specific type of gate, as well as demonstrating state preparation. Furthermore, we show that these gates can be utilized as a type of optical modulator as the Doppler shift that occurs during shuttling will make the light seen by shuttled ions different than that seen by stationary ions. Furthermore, we show that the shuttling operation can be utilized as an optical modulator, where the Doppler shift changes the frequency from that of a stationary ion.

42 ENGINEERING↗
DOE OSTI2021

Mid-infrared Pulsed Upconversion Imaging in a Rotating Detonation Combustor

To meet the challenges associated with performing mid-InfraRed (IR) imaging in Rotating Detonation Combustors (RDCs), a novel pulsed mid-IR UpConversion Imaging (UCI) diagnostic has been implemented. UCI is an alternative to direct mid-IR detection that uses nonlinear optical frequency mixing to shift mid-IR wavelengths carrying a target image to shorter wavelengths that can be imaged with high-performance silicon-based CCD/CMOS cameras. This approach offers several favorable properties including high spectral selectivity, high temporal resolution, and superior low-light detectivity. A hydrogen-air research RDC was operated with carbon dioxide addition to allow pulsed UCI imaging of mid-IR luminosity within the combustion channel from spontaneous thermal emissions. The resulting measurements demonstrate high spatiotemporal resolution capable of imaging small structures near the supersonically propagating detonation wave front. The results show how this technique can be used to observe sharp gradients and millimeter-scale structures in the high-temperature, high-pressure zones RDC flow fields.

White, Logan W.↗
DOE OSTI2022

8-Plate Multi-Resonant Coupling Using a Class-E 2 Power Converter for Misalignments in Capacitive Wireless Power Transfer

Misalignment is a common issue in wireless power transfer systems. It shifts the resonant frequency away from the operating frequency that affects the power flow and efficiency from the charging station to the load. This work proposes a novel capacitive wireless power transfer (CPT) using an 8-plate multi-resonant capacitive coupling to minimize the effect of misalignments. A single-active switch class-E 2 power converter is utilized to achieve multi-resonance through the selection of different resonant inductors. Simulations show a widening of the resonant frequency band which offers better performance than a regular 4-plate capacitive coupling for misalignments. The hardware results of the 8-plate multi-resonant coupling show an efficiency of 88.5% for the 20.8 W test, which is 18.3% higher than that of the regular 4-plate coupling. Because of the wider resonant frequency band {455–485 kHz}, compared with the regular 4-plate coupling, the proposed design minimized the output voltage drop by 15% for a 10% misalignment. Even for large misalignments, the 8-plate performance improved by 40% compared with the 4-plate coupling.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

PFLOTRAN-SIP: A PFLOTRAN Module for Simulating Spectral-Induced Polarization of Electrical Impedance Data

Spectral induced polarization (SIP) is a non-intrusive geophysical method that collects chargeability information (the ability of a material to retain charge) in the time domain or its phase shift in the frequency domain. Although SIP is a temporal method, it cannot measure the dynamics of flow and solute/species transport in the subsurface over long times (i.e., 10–100 s of years). Data collected with the SIP technique need to be coupled with fluid flow and reactive-transport models in order to capture long-term dynamics. To address this challenge, PFLOTRAN-SIP was built to couple SIP data to fluid flow and solute transport processes. Specifically, this framework couples the subsurface flow and transport simulator PFLOTRAN and geoelectrical simulator E4D without sacrificing computational performance. PFLOTRAN solves the coupled flow and solute-transport process models in order to estimate solute concentrations, which were used in Archie’s model to compute bulk electrical conductivities at near-zero frequency. These bulk electrical conductivities were modified while using the Cole–Cole model to account for frequency dependence. Using the estimated frequency-dependent bulk conductivities, E4D simulated the real and complex electrical potential signals for selected frequencies for SIP. These frequency-dependent bulk conductivities contain information that is relevant to geochemical changes in the system. This study demonstrated that the PFLOTRAN-SIP framework is able to detect the presence of a tracer in the subsurface. SIP offers a significant benefit over ERT in the form of greater information content. It provided multiple datasets at different frequencies that better constrained the tracer distribution in the subsurface. Consequently, this framework allows for practitioners of environmental hydrogeophysics and biogeophysics to monitor the subsurface with improved resolution.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1972

The estimation of nonstationary spectra from moving acoustic source distributions.

It is shown that the Blackman-Tukey estimation procedure provides a natural estimate of a nonstationary spectrum defined in terms of the acoustic sources. The pressure field from the moving source distribution is discussed together with the estimation procedure. The spectrum can be considered as a time-dependent partition of the variance of the pressure field over a Doppler shifted continuum of frequencies. It is found that the effect of nonstationarity on the bias and variance of the estimate is small in cases of practical interest, provided sources directionality is excluded.

Mcdaid, E.↗
NASA NTRS1973

Flyover and static tests to study flight velocity effects on jet noise of suppressed and unsuppressed plug nozzle configurations

Two spoke-type suppressor plug nozzles and a basic plug nozzle were tested for noise and thrust performance. The nozzles were mounted on an underwing nacelle on an F-106B aircraft, and tests were made both statically and in flyovers at Mach 0.4 at an altitude of 91 meters (300 ft). The flight and static data were adjusted to common reference conditions so that direct comparisons could be made. The noise characteristics that these nozzles would have on a large multiengine aircraft at a 640-meter (2100-ft) sideline distance are also presented. Flight noise levels for all three nozzles were higher than static at comparable conditions; and a shift in the frequency spectra was seen from static to flight, indicating the presence of a forward velocity effect on the noise characteristics.

Chamberlin, R.↗
NASA NTRS1976

Measurements of acoustic responses of gaseous propellant injectors

Results are presented for an investigation intended to provide experimental data that can quantitatively describe the way in which various coaxial injector designs affect the stability of gaseous propellant rocket motors. The response factors of configurations that simulate the flow conditions in a gaseous-fuel injector element and a gaseous-oxidizer injector element are measured by using a modified impedance-tube technique and under cold-flow conditions simulating those observed in rocket motors with axial instability. The measured injector response factor data are presented and discussed. It is shown that there is reasonable agreement between the measured injector response factors and those predicted by the Feiler and Heidmann model (1967), and that the orifice length can be varied to shift the resonant frequency of the injector without any change in the magnitude of the response factor at resonance. A change in the injector open-area ratio is found to have a significant effect on the characteristics of the injector response factor.

Janardan, B. A.↗
NASA NTRS1977

Forward flight effects on EBF noise

Forward flight effects on local mean velocity and turbulence velocity profiles, surface pressure spectra, and far field acoustic pressure spectra were measured for a simple externally blown flap (EBF). Both upper-surface-blowing and under-the-wing configurations were tested. Ratio of acoustic wind tunnel velocity to nozzle exhaust velocity was varied from 0 to 3/8 in steps of 1/8. A method was determined for predicting forward flight effects on surface-radiated noise. This noise is decreased in amplitude and shifted to higher frequency relative to data obtained at zero flight speed. Predictions are validated by comparisons with published NASA, Boeing, and Lockheed data.

Fink, M. R.↗
NASA NTRS1978

Digital phase shifter synchronizes local oscillators

Digital phase-shifting network is used as synchronous frequency multiplier for applications such as phase-locking two signals that may differ in frequency. Circuit has various phase-shift capability. Possible applications include data-communication systems and hybrid digital/analog phase-locked loops.

Ali, S. M.↗
NASA NTRS1978

Investigation of the dynamic range problem and providing software support for the AOL system

The present scheme for providing system timing for the airborne oceanographic lidar (AOL) system is not completely satisfactory. The possibility of using a digital approach to generate the forty pulses needed to energize the gates leading to the charge digitizers was investigated. The solution in terms of general analog and digital circuitry is straightforward. The crystal oscillator provides a stable frequency source which is used as a clock to the ring counter. The ring counter propagates a pulse from stage one to stage forty. Each of the outputs has an amplifier for isolation. This design is easy to implement in the frequency range up to 50 MHZ. Because a gate pulse width of from about 2 to 6 ns is needed for the AOL system, this dictates an input clock frequency to the shift register of from 100 MHA to 500 MHA. Problems associated with generating pulses in this range of operation are examined and an alternate solution is discussed.

Source record↗
NASA NTRS1979

Hyperfine resonance of gaseous atomic hydrogen at 4.2 K

The hyperfine frequency and wall shift of hydrogen atoms at 4.2 K stored in a bulb coated with solid H2 were measured. The phase shift per wall collision is -0.29(1) rad. The adsorption energy of H on H2 is 9(2) K, and the adsorption time at 4.2 K is approximately 30 nsec. Transverse and longitudinal relaxation times have been measured, and atomic densities greater than 10 to the 14th/cu cm have been observed.

Crampton, S. B.↗