Source Motion Research Articles

Framing the hydrothermal significance of water-based hybrid nanofluid flow over a revolving disk

Abstract In this article, the authors have presented the MHD hybrid nanoliquid flow comprised of CuO and Ag nanoparticles (nps) over a rotating disk under the effects of thermophoresis, Brownian motion, activation energy, heat source and chemical reaction. The flow is considered over a spinning disc with convective conditions. The proposed model is solved with the help of HAM. The convergence of the HAM is also shown in order to verify the convergence of the modeled problem. The effects of embedded parameters on the velocity, energy and mass profiles of the magnetohydrodynamic flow of hybrid nanoliquid are shown with the help of Figures. Also, the effects of embedded parameters on skin friction, heat and mass transfer rate are calculated with the help of Tables. The results showed that the velocity and energy profiles are augmented with the increasing solid volume fraction. The increasing magnetic parameter reduces both the radial and tangential velocities of the hybrid nanofluid flow. The increasing effects of heat source, thermophoresis and Brownian motion factors on energy profiles are found. The increasing influence of thermophoresis and activation energy factors on concentration profile of the hybrid nanofluid flow is found, while the increasing Brownian motion, chemical reaction and Schmidt number reduce the concentration profile.

Modeling and analytical analysis of dual diffusive Williamson nanoliquid considering generalized heat-mass concepts

The primary objective of this investigation is to explore the Cattaneo–Christov flux models impact on Williamson nanofluid over a stretching surface. Buongiorno’s model featuring diffusions (Brownian and thermophoretic) is opted for nonlinear analysis. Buoyancy-driven nonlinear convection flow in stagnation region is modeled. Surface is permeable and transpiration effects are considered. Energy expression captures heat source/sink aspects. The nondimensional differential systems are tackled analytically via homotopy analysis method (HAM). The profiles of dimensionless temperature, concentration and skin friction are examined graphically for the attributes of multiple physical parameters. It is revealed that the heat transfer elevates with the increment of thermophoresis, heat source and Brownian motion parameters while it dwindles with the improvement of thermal relaxation parameter. The mass transfer strengthens with the enlargement of thermophoresis parameter while diminishing with the enhancement of solutal relaxation and Brownian motion parameters. The skin friction is elevated for higher values of material variable against nonlinear mixed convection parameter.

Hologram formation by using vertical antenna in a shallow water waveguide

Holographic signal processing method by using a vertical linear antenna in shallow water is presented in the paper. Offered method of moving source sound field hologram formation by using vertical antenna is based on holographic signal processing of each element of vertical antenna. Sound field of source moving in shallow water waveguide creates a stable interference pattern (interferogram) in the frequency-time domain on each element of vertical antenna. The 2D-FT (2D Fourier transform) of the interferogram is antenna element hologram (AEH). AEH allows to coherently accumulate the sound intensity of the interferogram in a relatively small area as focal spots for each element of antenna. It is shown that the focal spots coordinates on AEH depends upon the source range, velocity, and motion direction. The focal spots coordinates on AEH are same for each element of antenna. The output antenna hologram is formed by superposition AEH. Relationship between focal spot coordinates on the antenna hologram and the source range, velocity, and motion direction are derived in the paper. The results of the numerical experiment of antenna hologram formation for low-frequency (100200 Hz) sound field of source moving in shallow water are presented. The results presented in the paper significantly expand the efficiency of interferometric signal processing in shallow water. [This study was supported by RFBR 19-29-06075, МК-6144.2021.4, and МК-4846.2022.4.]

Surface excitation of focused shear wave beams in soft elastic media: Experiment

Shear waves are employed in medical imaging to reveal variations in the viscoelastic properties of soft tissues, which are useful biomarkers for pathologies such as breast lesions and liver disease. Shear wave excitation methods that employ acoustic radiation force or surface vibration with a small piston have limitations associated with imaging depth and shear wave amplitude. We introduce a new method for surface excitation of shear waves that employs longitudinal motion of a concave-shaped piston source to generate a focused shear wave beam, thereby increasing shear wave amplitude and penetration depth. Focused shear waves are excited in a gel phantom in the frequency range of 200 Hz to 400 Hz using a concave piston with 40 mm radius of curvature and 50 mm diameter. The wave field comprises both transverse and longitudinal displacement components, which are polarized perpendicular and parallel to the propagation direction, respectively. Transversely and longitudinally polarized wave fields are measured using ultrasound speckle tracking. The longitudinally polarized shear wave is of interest because it is measured in elastography applications. Preliminary comparisons exhibit good agreement between measured beam patterns and those predicted by an analytical theory for shear wave beam propagation due to surface excitation with a piston source.

Detection of dynamic changes in interaural delay by older adults (L).

The ability of older adults (48 to 72) with relatively intact low-frequency hearing to detect the motion of an acoustic source was investigated using dynamically varying interaural delays. Thresholds were measured using a single-interval two-alternative forced-choice task in which listeners determined if the sound source was moving or stationary. Motion thresholds were significantly larger than stationary localization thresholds. No correlation was observed between age and motion-detection ability for the age range tested. An interesting finding was that there were similar thresholds for older and younger adults. Results suggest reliance on dominant low-frequency binaural timing cues unaffected by high-frequency hearing loss in older adults.

Lisa Zurk and Matched Field Processing—Her early career at MIT Lincoln Laboratory (1996–2005)

After completing her doctoral program in electromagnetics in 1995 Lisa decided to go to MIT Lincoln Laboratory to work on Matched Field Processing (MFP) in a nascent group formed for sonar and underwater acousitcs efforts. Then MFP introduced new methods of beamforming which were found to be sensitive to assumptions made for the sonar system, the environment and array processing. The so called adaptive one were especially sensitive. Lisa examined the importance of source motions and array are important for any sonar. In this context she introduced (i) mode based rank reduction, or modal MFP, (ii) array tile corrections, (iii) a “dynamic” snapshot correction method a focused MFP while the source is moving similar to beam steered MVDR, and (iv) “instantaneous” data and model based interference filtering. All these were subsequently discovered by later MFP researchers. Lisa and her coauthors were well ahead of there time.

Auditory motion as a cue for source segregation and selection in a "cocktail party" listening environment.

Source motion was examined as a cue for segregating concurrent speech or noise sources. In two different headphone-based tasks-motion detection (MD) and speech-on-speech masking (SI)-one source among three was designated as the target only by imposing sinusoidal variation in azimuth during the stimulus presentation. For MD, the lstener was asked which of the three concurrent sources was in motion during the trial. For SI, the listener was asked to report the words spoken by the moving speech source. MD performance improved as the amplitude of the sinusoidal motion (i.e., displacement in azimuth) increased over the range of values tested (±5° to ±30°) for both modulated noise and speech targets, with better performance found for speech. SI performance also improved as the amplitude of target motion increased. Furthermore, SI performance improved as word position progressed throughout the sentence. Performance on the MD task was correlated with performance on SI task across individual subjects. For the SI conditions tested here, these findings are consistent with the proposition that listeners first detect the moving target source, then focus attention on the target location as the target sentence unfolds.

Interferometric Imaging, and Beam-Formed Study of a Moving Type-IV Radio Burst with LOFAR

Type-IV radio bursts have been studied for over 50 years. However, the specifics of the radio emission mechanisms is still an open question. In order to provide more information about the emission mechanisms, we studied a moving Type-IV radio burst with fine structures (spike group) by using the high-resolution capability of the Low-Frequency Array (LOFAR) on August 25, 2014. We present a comparison of Nançay Radioheliograph (NRH) and the first LOFAR imaging data of the Type-IV radio burst. The degree of circular polarization (DCP) is calculated at frequencies in the range 20 – 180 MHz using LOFAR data, and it was found that the value of DCP gradually increased during the event, with values of 20 – 30%. LOFAR interferometric data were combined with white-light observations in order to track the propagation of this Type-IV burst. The kinematics shows a westward motion of the radio sources, slower than the CME leading edge. The dynamic spectrum of LOFAR shows a large number of fine structures with durations of less than 1 s and high brightness temperatures (T_{ mathrm{B}}), i.e., 10^{12} – 10^{13} K. The gradual increase of DCP supports gyrosynchrotron emission as the most plausible mechanism for the Type IV. However, coherent emissions such as Electron Cyclotron Maser (ECM) instability may be responsible for small-scale fine structures. Countless fine structures altogether were responsible for such high T_{mathrm{B}}.

Pairing-induced motion of source and inert particles driven by surface tension.

We experimentally and theoretically investigate systems with a pair of source and inert particles that interact through a concentration field. The experimental system comprises a camphor disk as the source particle and a metal washer as the inert particle. Both are floated on an aqueous solution of glycerol at various concentrations, where the glycerol modifies the viscosity of the aqueous phase. The particles form a pair owing to the attractive lateral capillary force. As the camphor disk spreads surface-active molecules at the aqueous surface, the camphor disk and metal washer move together, driven by the surface tension gradient. The washer is situated in the front of the camphor disk, keeping the distance constant during their motion, which we call a pairing-induced motion. The pairing-induced motion exhibited a transition between circular and straight motions as the glycerol concentration in the aqueous phase changed. Numerical calculations using a model that considers forces caused by the surface tension gradient and lateral capillary interaction reproduced the observed transition in the pairing-induced motion. Moreover, this transition agrees with the result of the linear stability analysis on the reduced dynamical system obtained by the expansion with respect to the particle velocity. Our results reveal that the effect of the particle velocity cannot be overlooked to describe the interaction through the concentration field.

Advanced Methods in Rotating Machines

The motions of power sources in industrial applications were always provided by electromechanical systems, which use around 70% of the gross energy consumption of industrialized economies [...]

Constraining Mass of M31 Combing Kinematics of Stars, Planetary Nebulae and Globular clusters

We construct a multiple-population discrete axisymmetric Jeans model for the Andromeda (M31) galaxy, considering three populations of kinematic tracers: 48 supergiants and 721 planetary nebulae (PNe) in the bulge and disk regions, 554 globular clusters extending to ∼30 kpc, and halo stars extending to ∼150 kpc of the galaxy. The three populations of tracers are organized in the same gravitational potential, while each population is allowed to have its own spatial distribution, rotation, and internal velocity anisotropy. The gravitational potential is a combination of stellar mass and a generalized NFW dark matter halo. We created two sets of models, one with a cusped dark matter halo and one with a cored dark matter halo. Both the cusped and cored model fit kinematics of all the three populations well, but the cored model is not preferred due to a too high concentration compared to that predicted from cosmological simulations. With a cusped dark matter halo, we obtained total stellar mass of 1.0 ± 0.1 × 1011 M ⊙, dark matter halo virial mass of M 200 = 7.0 ± 0.9 × 1011 M ⊙, virial radius of r 200 = 184 ± 4 kpc, and concentration of c = 20 ± 4. The mass of M31 we obtained is at the lower side of the allowed ranges in the literature and consistent with the previous results obtained from the H i rotation curve and PNe kinematics. Velocity dispersion profile of the outer stellar halo is important in constraining the total mass while it is still largely uncertain. Further proper motion of bright sources from Gaia or the Chinese Space Station Telescope might help on improving the data and lead to stronger constraints on the total mass of M31.

Spatial dependency of lesion detectability in digital breast tomosynthesis.

X-ray imaging results in inhomogeneous irradiation of the detector and distortion of structures in the periphery of the image; yet the spatial dependency of tomosynthesis image-quality metrics has not been extensively investigated. In this study, we use virtual clinical trials to quantify the spatial dependency of lesion detectability in our lab's next-generation tomosynthesis (NGT) system. Two geometries were analyzed: a conventional geometry with mediolateral source motion, and a NGT geometry with T-shaped motion. Breast parenchymal texture was simulated using an open-source library with Perlin noise using 400 random seeds and three breast densities. Spherical mass lesions were inserted in the central slice of the phantoms using the voxel additive method. Image acquisition was simulated using in-house ray-tracing software and simple backprojection was performed using commercial reconstruction software. Lesion detectability with Channelized Hotelling Observers (CHOs) was analyzed using receiver operating characteristic curves to measure the detectability index (d') at 154 unique locations for the lesions. We also divided images into three non-overlapping regions (differing in terms of distance from the chest wall). At the 0.05 level of significance, there was a statistically significant difference between the geometries in terms of d' in one of the three regions, with the T geometry offering superior detectability. Examining all 154 lesion locations, the T geometry was found to offer lower spread (standard deviation) in d' values throughout the image area, and superior d' at 83 of 154 locations (53.9%). In summary, the T geometry enables superior lesion detection and mitigates anisotropies.

Curved Jet Motion. I. Orbiting and Precessing Jets

Astrophysical jets are often observed as bent or curved structures. We also know that the different jet sources may be binary in nature, which may lead to a regular, periodic motion of the jet nozzle, an orbital motion, or precession. Here we present the results of 2D (M)HD simulations in order to investigate how a precessing or orbiting jet nozzle affects the propagation of a high-speed jet. We have performed a parameter study of systems with different precession angles, different orbital periods or separations, and different magnetic field strengths. We find that these kinds of nozzles lead to curved jet propagation, which is determined by the main parameters that define the jet nozzle. We find C-shaped jets from orbiting nozzles and S-shaped jets from precessing nozzles. Over a long time and long distances, the initially curved jet motion bores a broad channel into the ambient gas that is filled with high-speed jet material whose lateral motion is damped, however. A strong (longitudinal) magnetic field can damp the jet curvature that is enforced by either precession or orbital motion of the jet sources. We have investigated the force balance across the jet and ambient medium and found that the lateral magnetic pressure and gas pressure gradients are almost balanced, but that a lack of gas pressure on the concave side of the curvature is leading to the lateral motion. Magnetic tension does not play a significant role. Our results are obtained in code units, but we provide scaling relations such that our results may be applied to young stars, microquasars, symbiotic stars, or active galactic nuclei.

Equivalent heat source approach in a quasi-steady-state laser-GMAW hybrid welding simulation

A quasi-steady-state laser-GMAW hybrid welding simulation method was developed. The comprehensive effects of buoyancy, thermal capillary force, electromagnetic force and arc shear force were considered in the model, thus the temperature and flow fields characteristics of molten pool were obtained. At the same time, the heat source motion was realized based on the deformed geometry (DG) approach. The model can be applied to laser welding processes with different joint configurations or moving paths.

Photons with real magnetic charges and absurdity of concept expansion universe

The results of the study of the physics of photons with real magnetic charges showed that photons do not form any light waves. The circular frequency of photons produced under the conditions of the translational motion of the photon source differs from о by the value , which is determined solely by the change in the velocity ∆V of the translational motion of the photon source at the moment of photon formation. It is important to understand that the circular frequency of photons, born at any moment of the movement of their sources, is an internal property (parameter) of the photon and remains unchanged throughout the entire photon “life”. Moreover, the photon frequency cannot depend on any movements of the observer.

Observation of a star’s orbit based on the emission and propagation of light as mechanical phenomena

The hypothesis that the velocity of light depends on the motion of the light source was rejected by astronomers’ observations of binary stars and by the result of the experiment performed at CERN, Geneva, in 1964. Opposingly, the study of the emission, propagation, and reflection of light as mechanical phenomena concludes that the velocity of light depends on the velocity of the light source. According to this study, the human eye sees the orbit of a star larger than its actual size, and the light from the star on the observed orbit travels to the observer’s eyes at the emitted velocity <mml:math display="inline"> <mml:mi>c</mml:mi> </mml:math> ; therefore, there are no time irregularities. This paper exposes visual irregularities predicted by the hypothesis that the velocity of light is independent of the velocity of the light source.

Trials of transmission imaging using clinically used Ir-192 source for high-dose-rate brachytherapy

In high-dose-rate (HDR) brachytherapy, verification of an Ir-192 source's position during treatment is required. One of the methods for this used a high-energy pinhole gamma camera to image the position of the source, but the absolute position of the source cannot be measured. To confirm the absolute position, it will be useful to acquire the transmission image of a subject in addition to the gamma photon image at the same time without using an additional X-ray system. To measure the transmission images, we tried to use the high-energy gamma photons emitted from the Ir-192 source used for the therapy. We developed a high-energy gamma photon imaging system composed of 1-mm-thick Pr doped Gd2O2S (GOS), a surface mirror, and a cooled charge-coupled device (CCD) camera. The developed imaging system achieved transmission imaging of high-energy gamma photons by transporting the Ir-192 source in front of the imaging system. The spatial resolution of the imaging system was better than 2.4 mm FWHM with and without a 10-cm-thick acrylic block set between the imaging system and the source. Moderate spatial resolution and contrast images of phantoms were obtained with the system. For the dynamic imaging mode, continuous images of the phantoms were measured with 1-sec intervals. There was no observable difference in the transmission images by the movement of the Ir-192 source. Transmission imaging of subjects using an Ir-192 source for HDR brachytherapy could be achieved using our developed imaging system. The system offers a new method to measure the real-time transmission images of the subject during HDR brachytherapy.

Technical note: Analysis of brachytherapy source movement by high-speed camera.

To assess the accuracy of the movement of a brachytherapy source using a high-speed camera for evaluating source position, dwell time, and transit dose. A high-speed camera was used to record the source position of an Ir-192 source relative to a ruler within a custom positioning jig in a remote afterloading system. The analyzed frames can be used to assess dwell positions and times. Treatment plans had multiple dwell times equal to 0.1, 0.5, 1.0, and 2.0 s in 2.5- and 5-mm step sizes. Images were acquired at a rate of 146 frames/s. Acquired images were processed to automatically track the actual source using the correlation between a template image and each frame. The brachytherapy dose calculation formalism (AAPM TG43-U1) was applied to each frame to evaluate the transit dose contribution to the total dose. The differences in measured source positions from the nominal for dwell times equal to 0.1, 0.5, 1.0, and 2.0 s in treatment plans were approximately ≤1mm. The corresponding differences in measured dwell times from the nominal values at 5 mm steps were -15, -9, -5, and 5 ms, respectively. The source velocities at 5mm steps were approximately 393mm/s. The dose differences at 5mm from the source movement with and without the transit dose for these dwell times were 38%, 7%, 3%, and 2%, respectively. Recording a brachytherapy source using a high-speed camera allowed the evaluation of positional and dwell time accuracies as well as dosimetry assessments, such as the transit dose, based on the application of AAPM TG-43U1.

Characteristics of earthquake source and ground motions in Northern Vietnam investigated through the 2020 Moc Chau M5.0 earthquake sequence

• The strike-slip rupture mechanism has been verified by the moment tensor inversion. • The isoseismal map of earthquake intensity has been constructed based on field survey. • This earthquake is associated with the activation of the rank II Da River fault. • The site condition of each station is determined using HVSR for further applications. • Earthquake engineering application issues of this area have been clearly addressed. On July 27, 2020, a shallow earthquake with a moment magnitude (M w ) of 5.0 occurred near Moc Chau in Northwestern Vietnam. Several shallow aftershocks, clustered in a small area, followed the mainshock. The mainshock caused damage to infrastructure in the source area, and considerable shaking was felt in many high buildings in surrounding cities. This event was the first recorded significant earthquake by a newly operational Vietnam broadband seismic network. The ground motions of this earthquake sequence were adequately recorded by this network. The strike-slip rupture mechanisms of the events were evaluated through moment tensor inversion analysis. After this earthquake, a field survey was conducted. A combined analysis of damage patterns and source mechanisms revealed that this earthquake sequence might be associated with the active right-lateral Da River fault. The site classification of each station that recorded data on the Moc Chau series was evaluated by computing the horizontal-to-vertical spectral ratio. This earthquake sequence was analyzed to evaluate the characteristics of the earthquake source and the seismic wave propagation in Northwestern Vietnam and to address the potential earthquake engineering applications of this information.

Achieving Isotropic Super-Resolution with a Non-Isocentric Acquisition Geometry in a Next-Generation Tomosynthesis System.

We have constructed a prototype next-generation tomosynthesis (NGT) system that supports a non-isocentric acquisition geometry for digital breast tomosynthesis (DBT). In this geometry, the detector gradually descends in the superior-to-inferior direction. The aim of this work is to demonstrate that this geometry offers isotropic super-resolution (SR), unlike clinical DBT systems which are characterized by anisotropies in SR. To this end, a theoretical model of a sinusoidal test object was developed with frequency exceeding the alias frequency of the detector. We simulated two geometries: (1) a conventional geometry with a stationary detector, and (2) a non-isocentric geometry. The input frequency was varied over the full 360° range of angles in the plane of the object. To investigate whether SR was achieved, we calculated the Fourier transform of the reconstruction. The amplitude of the tallest peak below the alias frequency was measured relative to the peak at the input frequency. This ratio (termed the r-factor) should approach zero to achieve high-quality SR. In the conventional geometry, the r-factor was minimized (approaching zero) if the orientation of the frequency was parallel with the source motion, yet exceeded unity (prohibiting SR) in the orientation perpendicular to the source motion. However, in the non-isocentric geometry, the r-factor was minimized (approaching zero) for all orientations of the frequency, meaning SR was achieved isotropically. In summary, isotropic SR in DBT can be achieved using the non-isocentric acquisition geometry supported by the NGT system.