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DOE OSTI2020

Timestamp Error Detection and Estimation for PMU Data based on Linear Correlation between Relative Phase Angle and Frequency

Time synchronization is essential to synchro-phasor-based applications. However, Timestamp Error (TE) in synchrophasor data can result in application failures. This paper proposes a method for TE detection based on the linear correlation between frequency and relative phase angle. The TE converts the short-term relative phase angle from noise-like signal to one that linear with the frequency. Pearson Correlation Coefficient (PCC) is applied to measure the linear correlation and then detect the timestamp error. The time error is estimated based on the variation of frequency and relative phase angle. Case studies with actual synchrophasor data demonstrate the effectiveness of TE detection and excellent accuracy of TE estimation.

Yu, Wenpeng↗

DOE OSTI2023

Real-Time Detection and Localization of Line Trip Event Via Relative Phase Angles

Line trip events widely exist in power systems. They can result in power outages and a huge economic loss if not promptly detected and localized. To provide a fast and precise solution, this paper presents a Complete Coverage of Voltage Measurement (CCVM)-based line trip event detection algorithm and a Relative Phase Angle (RPA)-based line trip event localization algorithm. First, frequency and relative phase angle features during a line trip event are calculated. Then, the CCVM-based algorithm is proposed from both frequency and rate of change of frequency estimation algorithm aspects. Additionally, the RPA-based algorithm is presented, and two cases are studied to demonstrate the uniqueness of the proposed algorithm. Various experiments are conducted, where the simulation results demonstrate that the proposed CCVM-based algorithm can detect a line trip event as short as 2.07 ms. In addition, the RPA-based algorithm has 1.26 times higher localization accuracy compared with the frequency magnitude-based and phase angle-based algorithms. In conclusion, the experiment results on the examples from two interconnected power systems in the U.S. verified the performance of the proposed algorithms in wide-area power systems.

24 POWER TRANSMISSION AND DISTRIBUTION↗

NASA NTRS1985

Orbits: Computer simulation

In rotating machinery dynamics an orbit (Lissajous curve) represents the dynamic path of the shaft centerline motion during shaft rotation and resulting precession. The orbit can be observed with an oscilloscope connected to XY promixity probes. The orbits can also be simulated by a computer. The software for HP computer simulates orbits for two cases: (1) Symmetric orbit with four frequency components with different radial amplitudes and relative phase angles; and (2) Nonsymmetric orbit with two frequency components with two different vertical/horizontal amplitudes and two different relative phase angles. Each orbit carries a Keyphasor mark (one-per-turn reference). The frequencies, amplitudes, and phase angles, as well as number of time steps for orbit computation, have to be chosen and introduced to the computer by the user. The orbit graphs can be observed on the computer screen.

Muszynska, A.↗

NASA NTRS1979

Acoustic scattering by circular cylinders of various aspect ratios

The effects of acoustic scattering on the useful frequency range of pressure gradient microphones were investigated experimentally between ka values of 0.407 and 4.232 using two circular cylindrical models (L/D = 0.5 and 0.25) having a 25 cm outside diameter. Small condenser microphones, attached to preamplifiers by flexible connectors, were installed from inside the cylindrical bodies, and flush mounted on the exterior surface of the cylinders. A 38 cm diameter woofer in a large speaker enclosure was used as the sound source. Surface pressure augmentation and phase differences were computed from measured data for various sound wave incidence angles. Results are graphically compared with theoretical predictions supplied by NASA for ka = 0.407, 2.288, and 4.232. All other results are tabulated in the appendices. With minor exceptions, the experimentally determined pressure augmentations agreed within 0.75 dB with theoretical predictions. The agreement for relative phase angles was within 5 percent without any exceptions. Scattering parameter variations with ka and L/D ratio, as computed from experimental data, are also presented.

Maciulaitis, A.↗

DOE OSTI2024

Measurement of the branching fraction of ψ ( 2 S ) → γ π 0

Based on ( 2712.4 ± 14.1 ) × 10 6 ψ ( 2 S ) events, 7.9 fb − 1 ψ ( 3773 ) data, and 0.8 fb − 1 off-resonance data samples collected with the BESIII detector, we measure the branching fraction of ψ ( 2 S ) → γ π 0 and e + e − → γ π 0 form factor at momentum transfers Q 2 ∼ 13 GeV 2 . The e + e − → γ π 0 cross section is fitted with considering the interference between the ψ ( 2 S ) and continuum amplitudes and two solutions are found, B = 3.74 × 10 − 7 with ϕ = 3.93 rad and B = 7.87 × 10 − 7 with ϕ = 2.08 rad . Here, B is the branching fraction of ψ ( 2 S ) → γ π 0 and ϕ is the relative phase angle between the ψ ( 2 S ) and continuum amplitudes. Due to insufficient off-resonance data, the branching fraction B ( ψ ( 2 S ) → γ π 0 ) is determined to be in the range [ 2.7 , 9.7 ] × 10 − 7 within 1 standard deviation of the contour region. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Photoproduction of K + K − Pairs in Ultraperipheral Collisions

K + K − pairs may be produced in photonuclear collisions, either from the decays of photoproduced ϕ ( 1020 ) mesons or directly as nonresonant K + K − pairs. Measurements of K + K − photoproduction probe the couplings between the ϕ ( 1020 ) and charged kaons with photons and nuclear targets. The kaon-proton scattering occurs at energies far above those available elsewhere. We present the first measurement of coherent photoproduction of K + K − pairs on lead ions in ultraperipheral collisions using the ALICE detector, including the first investigation of direct K + K − production. There is significant K + K − production at low transverse momentum, consistent with coherent photoproduction on lead targets. In the mass range 1.1 < M K K < 1.4 GeV / c 2 above the ϕ ( 1020 ) resonance, for rapidity | y K K | < 0.8 and p T , K K < 0.1 GeV / c , the measured coherent photoproduction cross section is d σ / d y = 3.37 ± 0.61 ( stat ) ± 0.15 ( syst ) mb . The center-of-mass energy per nucleon of the photon-nucleus (Pb) system W γ Pb , n ranges from 33 to 188 GeV, far higher than previous measurements on heavy-nucleus targets. The cross section is larger than expected for ϕ ( 1020 ) photoproduction alone. The mass spectrum is fit to a cocktail consisting of ϕ ( 1020 ) decays, direct K + K − photoproduction, and interference between the two. The confidence regions for the amplitude and relative phase angle for direct K + K − photoproduction are presented. © 2024 CERN, for the ALICE Collaboration 2024 CERN

43 PARTICLE ACCELERATORS↗

NASA NTRS1962

AN AUTOMATIC MICROWAVE PHASE COMPARATOR

Method of measuring the relative phase angle between two signals of the same frequency with- out the use of modulators or frequency translators

PHASE ANGLE↗

NASA NTRS1970

Array phasing device Patent

Apparatus for generating microwave signals at progressively related phase angles for driving antenna array

Carson, P. R.↗

NASA NTRS1985

Turbine blade friction damping study

A lumped parameter method, implemented on a VAX 11/780 computer shows that the primary parameters affecting the performance of the friction damper of the first stage turbine of the SSME high pressure fuel pump are: the damper-blade coefficient of friction; the normal force applied to the friction interface; the amplitude of the periodic forcing function; the relative phase angle of the forcing functions for adjacent blades bridged by a damper (effectively, the engine order of the forcing function); and the amount of hysteretic damping that acts to limit the vibration amplitude of the blade in its resonance modes. The low order flexural resonance vibration modes of HPFTP blades without dampers, with production dampers, and with two types of lightweight experimental dampers were evaluated in high speed spin pit tests. Results agree with those of the analytical study in that blades fitted with production friction dampers experienced the airfoil-alone flexural resonance mode, while those without dampers or with lighter weight dampers did not. No blades fitted with dampers experienced the whole blade flexural resonance mode during high speed tests, while those without dampers did.

Dominic, R. J.↗

NASA NTRS1986

Electromagnetic instabilities and gyrophase-bunched particles

The linear theory of electromagnetic instabilities at propagation parallel or antiparallel to a uniform magnetic field B(0) is used to calculate the relative phase angle between the fluctuating velocity vector of the jth component and the fluctuating magnetic field. A criterion that determines when this phase relationship leads to observable gyrophase bunching during the linear growth phase of an instability is also derived. The theory is applied to bunching of ion components by ion beam instabilities. Among the electromagnetic cool ion beam instabilities, it is found that the right-hand resonant mode is most likely to cause observable gyrophase bunching of an ion beam during linear growth.

Gary, S. P.↗

NASA NTRS1999

A Mode Detection Method Using the Azimuthal Directivity of a Turbofan Model

The azimuthal, far field directivity of a scale fan model was measured in high resolution. The model is a 12 inch diameter rotor with 16 blades followed by 40 stator vanes. The tests were conducted at the nominal 100% speed corresponding to a tip speed of 905 ft/sec. Measurement of the radiated sound field, forward of the fan, was made in an anechoic chamber with an inflow control device and a baffle separating the aft and forward radiated interaction noise. The acoustic field was surveyed with a circular hoop array of 16 microphones which was moved to 14 axial stations. At each axial station the hoop was rotated in half-degree increments to take 736 points in the azimuthal angle. In addition to sound pressure level, the phase angle relative to a reference microphone was measured at each point. The sound pressure level is shown to vary in patterns by 10-15 dB especially for the fundamental tone but also for the first and second harmonic. A far field mode detection method has been developed and used with the data which determines the modes generated by the fan and which then interact to form the azimuthal directivity.

Thomas, R. H.↗

NASA NTRS2016

Effect of AFT Rotor on the Inter-Rotor Flow of an Open Rotor Propulsion System

The effects of the aft rotor on the inter-rotor flow field of an open rotor propulsion rig were examined. A Particle Image Velocimetry (PIV) dataset that was acquired phase locked to the front rotor position has been phase averaged based on the relative phase angle between the forward and aft rotors. The aft rotor phase was determined by feature tracking in raw PIV images through an image processing algorithm. The effect of the aft rotor potential field on the inter-rotor flow were analyzed and shown to be in good agreement with Computational Fluid Dynamics (CFD) simulations. It was shown that the aft rotor had no substantial effect on the position of the forward rotor tip vortex but did have a small effect on the circulation strength of the vortex when the rotors were highly loaded.

Counter Rotating↗

NASA NTRS2016

Effect of Aft Rotor on the Inter-Rotor Flow of an Open Rotor Propulsion System

The effects of the aft rotor on the inter-rotor flow field of an open rotor propulsion rig were examined. A Particle Image Velocimetry (PIV) dataset that was acquired phase locked to the front rotor position has been phase averaged based on the relative phase angle between the forward and aft rotors. The aft rotor phase was determined by feature tracking in raw PIV images through an image processing algorithm. The effects of the aft rotor potential field on the inter-rotor flow were analyzed and shown to be in reasonably good agreement with Computational Fluid Dynamics (CFD) simulations. The aft rotor position was shown to have a significant upstream effect, with implications for front rotor interaction noise. It was found that the aft rotor had no substantial effect on the position of the forward rotor tip vortex but did have a small effect on the circulation strength of the vortex when the rotors were highly loaded.

Counter Rotating↗

NASA NTRS1983

Cross spectra between temperature and pressure in a constant area duct downstream of a combustor

The feasibility of measuring pressure temperature cross spectra and coherence and temperature-temperature cross spectra and coherence at spatially separated points along with pressure and temperature auto-spectra in a combustion rig was investigated. The measurements were made near the inlet and exit of a 6.44 m long duct attached to a J-47 combustor. The fuel used was Jet A. The cross spectra and coherence measurements show the pressure and temperature fluctuations correlate best at low frequencies. At the inlet the phenomena controlling the phase relationship between pressure and temperature could not be identified. However, at the duct exit the phase angle of the pressure is related to the phase angle of the temperature by the convected flow time delay.

Miles, J. H.↗

NASA NTRS1983

Cross spectra between temperature and pressure in a constant area duct downstream of a combustor

Miles, J. H.↗

NASA NTRS1986

The Voyager encounter with Uranus and Neptune

Voyager 2 approaches Uranus at a relative low phase angle and high southerly latitude. Only when the spacecraft is very close to Uranus does the geometry change appreciably. Most of the important observations occur within six hours of closest approach. Voyager flies through an Earth and solar occulation zone and leaves Uranus at a relatively high phase angle of about 145 degrees. There isn't much of an opportunity to look at the equatorial region of the planet. At Neptune, on the other hand, the approach is more nearly equatorial (about 35 deg S lat). Voyager 2 will come much closer to Nepture than to any of the other gas giants as it skims within about 2000 km of Neptune's cloudtops. It will pass through earth and solar occultation zones at both Neptune and its satellite, Triton. Again, Voyager 2 will leave Neptune at about 35 deg S latitude. Voyager operational instrument, interplanetary trajectories and planetary encounters are briefly discussed.

Miner, Ellis D.↗

NASA NTRS1984

The lightcurve and phase relation of the asteroid 133 Cyrene

The asteroid 133 Cyrene was observed photometrically on 17 nights during oppositions in 1979 and 1980. The synodic period of rotation was found to be 12.708 + or - 0.001 h with an amplitude of 0.30 m during both oppositions. At large phase angles, the phase relation is quite ordinary (0.025 mag/degree); however, the low phase angle observations reveal a dramatic opposition brightening, about 0.2 mag/degree near zero phase angle. The absolute magnitude, V(1,0), extrapolated with the above linear phase coefficient, is 8.40. The following color indices were also measured: B-V = 0.90, U-B = 0.51.

Harris, A. W.↗

NASA NTRS1991

Anomalous scattering of light on Triton

Researchers report here the discovery of an isolated region of anomalously forward scattering materials on the surface of Triton. The researchers' best-fit Hapke parameters indicate that regolith particles in the anomalous scattering region are not only less backward scattering, but also slightly lower in single scattering albedo than average materials on Triton's surface. While it might be possible to account for such differences in terms of differences in particle size and transparency, it is also possible that the anomalous region is compositionally distinct from other terrains. It is noteworthy that, for the anomalous region, there exists a distinctively strong spatial correlation between the photometric ratios at different phase angles, and that, relative to other terrains, the anomalous region reddens at a different rate with increasing phase angle.

Helfenstein, Paul↗