keyword
https://read.qxmd.com/read/37824323/efficient-stratified-3d-scatterer-sampling-for-freehand-ultrasound-simulation
#21
JOURNAL ARTICLE
Francois Gaits, Nicolas Mellado, Gauthier Bouyjou, Damien Garcia, Adrian Basarab
Ultrasound image simulation is a well-explored field with the main objective of generating realistic synthetic images, further used as ground truth for computational imaging algorithms, or for radiologists' training. Several ultrasound simulators are already available, most of them consisting in similar steps: (i) generate a collection of tissue mimicking individual scatterers with random spatial positions and random amplitudes, (ii) model the ultrasound probe and the emission and reception schemes, (iii) generate the RF signals resulting from the interaction between the scatterers and the propagating ultrasound waves...
October 12, 2023: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://read.qxmd.com/read/37788989/drifting-discrete-jovian-radio-bursts-reveal-acceleration-processes-related-to-ganymede-and-the-main-aurora
#22
JOURNAL ARTICLE
Emilie Mauduit, Philippe Zarka, Laurent Lamy, Sébastien L G Hess
Radio detection at high time-frequency resolutions is a powerful means of remotely studying electron acceleration processes. Radio bursts have characteristics (polarization, drift, periodicity) making them easier to detect than slowly variable emissions. They are not uncommon in solar system planetary magnetospheres, the powerful Jovian "short bursts (S-bursts)" induced by the Io-Jupiter interaction being especially well-documented. Here we present a detection method of drifting radio bursts in terabytes of high resolution time-frequency data, applied to one month of ground-based Jupiter observations...
October 3, 2023: Nature Communications
https://read.qxmd.com/read/37765956/an-assessment-of-environmental-rf-noise-due-to-iot-deployment
#23
JOURNAL ARTICLE
Dominique G K Ingala, Nelendran Pillay, Aritha Pillay
The advent of the Internet of Things (IoT) has contributed to an increase in the production volume of RF-featured equipment. According to statistics from the literature, the IoT industry will soon deploy billions of products. While the concept behind these applications seems exciting, this paper sought to assess the effects the radio emissions produced by IoT products would have on the ambient radio noise levels within the unlicensed frequency bands of 433 MHz, 868 MHz, and 2.4 GHz. The study extended to three environments: industrial, urban, and suburban...
September 15, 2023: Sensors
https://read.qxmd.com/read/37765917/soot-monitoring-of-gasoline-particulate-filters-using-a-radio-frequency-based-sensor
#24
JOURNAL ARTICLE
Stefanie Walter, Peter Schwanzer, Gunter Hagen, Hans-Peter Rabl, Markus Dietrich, Ralf Moos
Owing to increasingly stringent emission limits, particulate filters have become mandatory for gasoline-engine vehicles. Monitoring their soot loading is necessary for error-free operation. The state-of-the-art differential pressure sensors suffer from inaccuracies due to small amounts of stored soot combined with exhaust gas conditions that lead to partial regeneration. As an alternative approach, radio-frequency-based (RF) sensors can accurately measure the soot loading, even under these conditions, by detecting soot through its dielectric properties...
September 13, 2023: Sensors
https://read.qxmd.com/read/37763297/improving-structural-mri-preprocessing-with-hybrid-transformer-gans
#25
JOURNAL ARTICLE
Ovidijus Grigas, Rytis Maskeliūnas, Robertas Damaševičius
Magnetic resonance imaging (MRI) is a technique that is widely used in practice to evaluate any pathologies in the human body. One of the areas of interest is the human brain. Naturally, MR images are low-resolution and contain noise due to signal interference, the patient's body's radio-frequency emissions and smaller Tesla coil counts in the machinery. There is a need to solve this problem, as MR tomographs that have the capability of capturing high-resolution images are extremely expensive and the length of the procedure to capture such images increases by the order of magnitude...
September 11, 2023: Life
https://read.qxmd.com/read/37723730/natural-sources-of-intense-ultra-high-frequency-radiation-in-high-voltage-atmospheric-discharges
#26
JOURNAL ARTICLE
E V Parkevich, A I Khirianova, T F Khirianov, I S Baidin, K V Shpakov, D V Tolbukhin, A A Rodionov, Ya K Bolotov, V A Ryabov, S A Ambrozevich, A V Oginov
We study the sources of intense ultra-high-frequency (UHF) radiation (in the frequency range 1-6 GHz) arising during the development of high-voltage atmospheric discharges. The discharges were initiated in a long discharge gap by applying an approximately 1-MV pulse with positive or negative polarity. By employing a radio registration system based on ultrawideband antennas, we managed to localize the UHF radiation sources in the discharge with centimeter accuracy and investigate their temporal and spatial correlation with the discharge structures...
August 2023: Physical Review. E
https://read.qxmd.com/read/37712991/generation-of-dual-and-quad-optical-frequency-combs-in-the-injected-radiation-free-mode-locked-frequency-shifted-feedback-laser
#27
JOURNAL ARTICLE
Sergey N Mantsevich, Ekaterina I Kostyleva, Andrey N Danilin, Vladimir S Khorkin
The results of an optoelectronic system-frequency-shifted feedback (FSF) laser experimental examination are presented. The considered FSF laser is seeded only with optical amplifier spontaneous emission (ASE) and operates in the mode-locked regime, whereby the output radiation is sequence of short pulses with a repetition rate determined by the delay time in its optical feedback circuit. In the frequency domain, the spectrum of such a pulse sequence is an optical frequency comb (OFC). These OFCs we call initial...
September 15, 2023: Front Optoelectron
https://read.qxmd.com/read/37682993/electromagnetically-unclonable-functions-generated-by-non-hermitian-absorber-emitter
#28
JOURNAL ARTICLE
Minye Yang, Zhilu Ye, Hongyi Pan, Mohamed Farhat, Ahmet Enis Cetin, Pai-Yen Chen
Physically unclonable functions (PUFs) are a class of hardware-specific security primitives based on secret keys extracted from integrated circuits, which can protect important information against cyberattacks and reverse engineering. Here, we put forward an emerging type of PUF in the electromagnetic domain by virtue of the self-dual absorber-emitter singularity that uniquely exists in the non-Hermitian parity-time ( PT )-symmetric structures. At this self-dual singular point, the reconfigurable emissive and absorptive properties with order-of-magnitude differences in scattered power can respond sensitively to admittance or phase perturbations caused by, for example, manufacturing imperfectness...
September 8, 2023: Science Advances
https://read.qxmd.com/read/37576658/design-and-development-of-high-entropy-alloys-with-a-tailored-composition-and-phase-structure-based-on-thermodynamic-parameters-and-film-thickness-using-a-novel-combinatorial-target
#29
JOURNAL ARTICLE
Khurshed Alam, Woohyung Jang, Geonwoo Jeong, Chul-Kyu Park, Kwangmin Lee, Hoonsung Cho
This study presents a novel synthesis route for high-entropy alloys (HEAs) and high-entropy metallic glass (HEMG) using radio frequency (RF) magnetron sputtering and controlling the HEA phase selection according to atomic size difference (δ) and film thickness. The preparation of HEAs using sputtering requires either multitargets or the preparation of a target containing at least five distinct elements. In developing HEA-preparation techniques, the emergence of a novel sputtering target system is promising to prepare a wide range of HEAs...
August 8, 2023: ACS Omega
https://read.qxmd.com/read/37515131/sars-cov-2-inactivation-in-aerosol-by-means-of-radiated-microwaves
#30
JOURNAL ARTICLE
Antonio Manna, Davide De Forni, Marco Bartocci, Nicola Pasculli, Barbara Poddesu, Florigio Lista, Riccardo De Santis, Donatella Amatore, Giorgia Grilli, Filippo Molinari, Alberto Sangiovanni Vincentelli, Franco Lori
Coronaviruses are a family of viruses that cause disease in mammals and birds. In humans, coronaviruses cause infections on the respiratory tract that can be fatal. These viruses can cause both mild illnesses such as the common cold and lethal illnesses such as SARS, MERS, and COVID-19. Air transmission represents the principal mode by which people become infected by SARS-CoV-2. To reduce the risks of air transmission of this powerful pathogen, we devised a method of inactivation based on the propagation of electromagnetic waves in the area to be sanitized...
June 27, 2023: Viruses
https://read.qxmd.com/read/37420701/surface-properties-of-global-land-surface-microwave-emissivity-derived-from-fy-3d-mwri-measurements
#31
JOURNAL ARTICLE
Ronghan Xu, Zharong Pan, Yang Han, Wei Zheng, Shengli Wu
Land surface microwave emissivity is crucial to the accurate retrieval of surface and atmospheric parameters and the assimilation of microwave data into numerical models over land. The microwave radiation imager (MWRI) sensors aboard on Chinese FengYun-3 (FY-3) series satellites provide valuable measurements for the derivation of global microwave physical parameters. In this study, an approximated microwave radiation transfer equation was used to estimate land surface emissivity from MWRI by using brightness temperature observations along with corresponding land and atmospheric properties obtained from ERA-Interim reanalysis data...
June 13, 2023: Sensors
https://read.qxmd.com/read/37393352/effect-of-an-additional-floating-electrode-on-radio-frequency-cross-field-atmospheric-pressure-plasma-jet
#32
JOURNAL ARTICLE
Radhika T P, Satyananda Kar
Atmospheric pressure plasma jets with cross-field electrode configuration are a potential jet design for gases with high breakdown fields. This study focuses on the effect of an additional floating electrode on the cross-field plasma jet properties. Detailed experiments are done with the additional floating electrodes of different widths introduced below the ground electrode in a plasma jet with a cross-field electrode configuration. It is observed that in the presence of an additional floating electrode in the jet propagation path, less applied power is needed for the plasma jet to cross the nozzle and jet length increases...
July 1, 2023: Scientific Reports
https://read.qxmd.com/read/37390415/reconnection-powered-fast-radio-transients-from-coalescing-neutron-star-binaries
#33
JOURNAL ARTICLE
Elias R Most, Alexander A Philippov
It is an open question whether and how gravitational wave events involving neutron stars can be preceded by electromagnetic counterparts. This Letter shows that the collision of two neutron stars with magnetic fields well below magnetar-level strengths can produce millisecond fast-radio-burst-like transients. Using global force-free electrodynamics simulations, we identify the coherent emission mechanism that might operate in the common magnetosphere of a binary neutron star system prior to merger. We predict that the emission show have frequencies in the range of 10-20 GHz for magnetic fields of B^{*}=10^{11}  G at the surfaces of the stars...
June 16, 2023: Physical Review Letters
https://read.qxmd.com/read/37247313/universal-synthetic-aperture-sequence-for-anatomic-functional-and-super-resolution-imaging
#34
JOURNAL ARTICLE
Jorgen Arendt Jensen, Borislav Gueorguiev Tomov, Lars Emil Haslund, Nathalie Sarup Panduro, Charlotte Mehlin Sorensen
Synthetic Aperture (SA) can be used for both anatomic and functional imaging, where tissue motion and blood velocity are revealed. Often, sequences optimized for anatomic B-mode imaging are different from functional sequences, as the best distribution and number of emissions are different. B-mode sequences demand many emissions for a high contrast, whereas flow sequences demand short sequences for high correlations yielding accurate velocity estimates. This paper hypothesizes that a single, universal sequence can be developed for linear array SA imaging...
May 29, 2023: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://read.qxmd.com/read/37183171/the-steady-state-altadena-raser-generates-continuous-nmr-signals
#35
JOURNAL ARTICLE
Jing Yang, Peng Wang, Jan G Korvink, Jürgen J Brandner, Sören Lehmkuhl
A RASER (Radio Amplification by Stimulated Emission of Radiation) facilitates the study of nonlinear phenomena, as well as the determination of NMR parameters with high-precision. To achieve maximum sensitivity in the desired operating mode, it is crucial to control the RASER over long periods of time. So far, this was only possible at ultra-low magnetic fields. Here, we introduce a way to control the operating regime of a RASER at a magnetic field of 1.45 T. We employ a continuous-flow RASER, pumped by PHIP (ParaHydrogen Induced Polarization)...
May 14, 2023: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://read.qxmd.com/read/37172079/-13-c-radiofrequency-amplification-by-stimulated-emission-of-radiation-threshold-sensing-of-chemical-reactions
#36
JOURNAL ARTICLE
Andreas B Schmidt, Isaiah Adelabu, Christopher Nelson, Shiraz Nantogma, Valerij G Kiselev, Maxim Zaitsev, Abubakar Abdurraheem, Henri de Maissin, Matthew S Rosen, Sören Lehmkuhl, Stephan Appelt, Thomas Theis, Eduard Y Chekmenev
Conventional nuclear magnetic resonance (NMR) enables detection of chemicals and their transformations by exciting nuclear spin ensembles with a radio-frequency pulse followed by detection of the precessing spins at their characteristic frequencies. The detected frequencies report on chemical reactions in real time and the signal amplitudes scale with concentrations of products and reactants. Here, we employ Radiofrequency Amplification by Stimulated Emission of Radiation (RASER), a quantum phenomenon producing coherent emission of 13 C signals, to detect chemical transformations...
May 12, 2023: Journal of the American Chemical Society
https://read.qxmd.com/read/37141062/single-fiber-transducer-arrays-for-3d-ultrasound-computed-tomography-from-requirements-to-results
#37
JOURNAL ARTICLE
M Angerer, M Zapf, S Gebhardt, H Neubert, N V Ruiter
A potential method for future breast cancer screening is 3D ultrasound computed tomography (USCT). The utilized image reconstruction algorithms require transducer characteristics fundamentally different from conventional transducer arrays, leading to the necessity of a custom design. This design has to provide random transducer positioning, isotropic sound emission as well as a large bandwidth and wide opening angle. In this paper, we present a new transducer array design to be utilized in a third generation 3D USCT system...
May 4, 2023: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://read.qxmd.com/read/37115844/row-column-beamformer-for-fast-volumetric-imaging
#38
JOURNAL ARTICLE
Lasse Thurmann Jorgensen, Sebastian Kazmarek Praesius, Matthias Bo Stuart, Jorgen Arendt Jensen
This work presents a beamforming procedure that significantly reduces the number of operations when performing volumetric synthetic aperture imaging with row-column addressed arrays (RCAs). The proposed beamformer uses that the image values along the elevation direction of the low-resolution volume (LRV) are approximately constant. It is thus hypothesized that the entire LRV could be reconstructed from a single 2-D cross-section of the LRV. The presented method contains two stages; The first stage beamforms, for each emission, a cross-section using the conventional RCA beamformer...
April 28, 2023: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://read.qxmd.com/read/37034392/juno-plasma-wave-observations-at-ganymede
#39
JOURNAL ARTICLE
W S Kurth, A H Sulaiman, G B Hospodarsky, J D Menietti, B H Mauk, G Clark, F Allegrini, P Valek, J E P Connerney, J H Waite, S J Bolton, M Imai, O Santolik, W Li, S Duling, J Saur, C Louis
The Juno Waves instrument measured plasma waves associated with Ganymede's magnetosphere during its flyby on 7 June, day 158, 2021. Three distinct regions were identified including a wake, and nightside and dayside regions in the magnetosphere distinguished by their electron densities and associated variability. The magnetosphere includes electron cyclotron harmonic emissions including a band at the upper hybrid frequency, as well as whistler-mode chorus and hiss. These waves likely interact with energetic electrons in Ganymede's magnetosphere by pitch angle scattering and/or accelerating the electrons...
December 16, 2022: Geophysical Research Letters
https://read.qxmd.com/read/37028315/precise-estimation-of-intravascular-pressure-gradients
#40
JOURNAL ARTICLE
Lars Emil Haslund, Lasse Thurmann Jorgensen, Matthias Bo Stuart, Marie Sand Traberg, Jorgen Arendt Jensen
This study presents a method for noninvasive pressure gradient estimation, which allows the detection of small pressure differences with higher precision compared to invasive catheters. It combines a new method for estimating the temporal acceleration of the flowing blood with the Navier-Stokes equation. The acceleration estimation is based on a double cross-correlation approach, which is hypothesized to minimize the influence of noise. Data are acquired using a 256-element, 6.5-MHz GE L3-12-D linear array transducer connected to a Verasonics research scanner...
May 2023: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
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