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radio frequency emission

Giovanni Nardini, Antonio Virdis, Claudia Campolo, Antonella Molinaro, Giovanni Stea
Platooning is a cooperative driving application where autonomous/semi-autonomous vehicles move on the same lane in a train-like manner, keeping a small constant inter-vehicle distance, in order to reduce fuel consumption and gas emissions and to achieve safe and efficient transport. To this aim, they may exploit multiple on-board sensors (e.g., radars, LiDARs, positioning systems) and direct vehicle-to-vehicle communications to synchronize their manoeuvres. The main objective of this paper is to discuss the design choices and factors that determine the performance of a platooning application, when exploiting the emerging cellular vehicle-to-everything (C-V2X) communication technology and considering the scheduled mode, specified by 3GPP for communications over the sidelink assisted by the eNodeB...
May 11, 2018: Sensors
Guillermo Robles, José Manuel Fresno, Juan Manuel Martínez-Tarifa
Spatial localization of emitting sources is especially interesting in different fields of application. The focus of an earthquake, the determination of cracks in solid structures, or the position of bones inside a body are some examples of the use of multilateration techniques applied to acoustic and vibratory signals. Radar, GPS and wireless sensors networks location are based on radiofrequency emissions and the techniques are the same as in the case of acoustic emissions. This paper is focused on the determination of the position of sources of partial discharges in electrical insulation for maintenance based on the condition of the electrical equipment...
May 3, 2018: Sensors
Qingmeng Wu, Mengting Si, Bing Zhang, Kang Zhang, Huanhuan Li, Longfei Mi, Yang Jiang, Rong Yan, Junling Chen, Yingcui Fang
By studying oxidation of AgNPs and decomposition of the produced silver oxide, we demonstrate that the localized surface plasmon resonance (LSPR) of Ag nanoparticles (AgNPs) was damped by Ag2O produced during oxygen plasma irradiation (OPI). The AgNPs were fabricated by evaporation of high pure silver under high vacuum. The oxidation was conducted in oxygen plasma generated by radio frequency (rf) glow discharging in vacuum, and the decomposition was performed by annealing the silver oxide in nitrogen ambient at temperatures ranging from room temperature to 450 0C...
April 26, 2018: Nanotechnology
Donghwan Kim, Hyunsuk Lee, Joohyeon Bae, Hyomin Jeong, Byeongkeun Choi, Taehyun Nam, Jungpil Noh
Ti-Ni shape memory alloy (SMA) thin films are very attractive material for industrial and medical applications such as micro-actuator, micro-sensors, and stents for blood vessels. An important property besides shape memory effect in the application of SMA thin films is the adhesion between the film and the substrate. When using thin films as micro-actuators or micro-sensors in MEMS, the film must be strongly adhered to the substrate. On the other hand, when using SMA thin films in medical devices such as stents, the deposited alloy thin film must be easily separable from the substrate for efficient processing...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Andrei Postnikov, Kamil Moldosanov
Gold nanoparticles (GNPs) may serve as "devices" to emit electromagnetic radiation in the terahertz (THz) range, whereby the energy is delivered by radio frequency or microwave photons which won't by themselves induce transitions between sparse confinement-shaped electron levels of a GNP, but may borrow the energy from longitudinal acoustic phonons to overcome the confinement gap. Upon excitation, the Fermi electron cannot relax otherwise than via emitting a THz photon, the other relaxation channels being blocked by force of shape and size considerations...
April 18, 2018: Nanotechnology
B W Stappers, E F Keane, M Kramer, A Possenti, I H Stairs
Pulsars are highly magnetized and rapidly rotating neutron stars. As they spin, the lighthouse-like beam of radio emission from their magnetic poles sweeps across the Earth with a regularity approaching that of the most precise clocks known. This precision combined with the extreme environments in which they are found, often in compact orbits with other neutron stars and white dwarfs, makes them excellent tools for studying gravity. Present and near-future pulsar surveys, especially those using the new generation of telescopes, will find more extreme binary systems and pulsars that are more precise 'clocks'...
May 28, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Hum Nath Parajuli, Haymen Shams, Luis Guerrero Gonzalez, Eszter Udvary, Cyril Renaud, John Mitchell
The filter bank multicarrier (FBMC) modulation format is considered as a potential candidate for future wireless 5G due to its feature of high suppression for out-of-band emissions, which allows combining multiple sub-bands with very narrow band-gaps, and hence increases the overall wireless transmission capacity. In this paper, we experimentally demonstrate the generation of multi sub-bands FBMC signals at millimeter-wave (mm-wave) for radio-over-fiber (RoF) systems. The designed multi sub-bands FBMC system consists of 5 sub-bands of 800 MHz with inter sub-band gaps of 781...
March 19, 2018: Optics Express
Negar Omidvari, Geoffrey Topping, Jorge Cabello, Stephan Paul, Markus Schwaiger, Sibylle I Ziegler
Compromises in the design of a positron emission tomography (PET) insert for a magnetic resonance imaging (MRI) system should minimize the deterioration of image quality in both modalities, particularly when simultaneous demanding acquisitions are performed. In this work, the advantages of using individually read-out crystals with high-gain silicon photomultipliers (SiPMs) were studied with a small animal PET insert for a 7 T MRI system, in which the SiPM charge was transferred to outside the MRI scanner using coaxial cables...
March 27, 2018: Physics in Medicine and Biology
Philipp Strobel, Volker Weiler, Peter Schmidt, Wolfgang Schnick
M[BeSi2N4] (M = Sr,Eu), crystallizing in the hexagonal space group P6¯2c, was synthesized from Sr(NH2)2, Be3N2 and "Si(NH)2" in W crucibles under N2 atmosphere in a radio-frequency furnace. The crystal structure was solved from powder X-ray diffraction data by the charge flipping method (Sr[BeSi2N4]: a = 4.86082(2), c = 9.42263(4) Å, Z = 2; Eu[BeSi2N4]: a = 4.85848(1), c = 9.41615(4) Å). M[BeSi2N4] contains a highly condensed rigid network of trigonal planar [BeN3] units that are connected to Si2N7 double tetrahedra by common vertices...
March 25, 2018: Chemistry: a European Journal
Andrew Mezentsev, Nikolai Lehtinen, Nikolai Østgaard, F J Pérez-Invernón, Steven A Cummer
We compared the modeled energy spectral density of very low frequency (VLF) radio emissions from terrestrial gamma ray flashes (TGFs) with the energy spectral density of VLF radio sferics recorded by Duke VLF receiver simultaneously with those TGFs. In total, six events with world wide lightning location network (WWLLN) defined locations were analyzed to exhibit a good fit between the modeled and observed energy spectral densities. In VLF range the energy spectral density of the TGF source current moment is found to be dominated by the contribution of secondary low-energy electrons and independent of the relativistic electrons which play their role in low-frequency (LF) range...
January 16, 2018: Journal of Geophysical Research. Atmospheres: JGR
Nissim Kanekar, Tapasi Ghosh, Jayaram N Chengalur
We have used the Arecibo Telescope to carry out one of the deepest-ever integrations in radio astronomy, targeting the redshifted conjugate satellite OH 18 cm lines at z≈0.247 towards PKS 1413+135. The satellite OH 1720 and 1612 MHz lines are, respectively, in emission and absorption, with exactly the same line shapes due to population inversion in the OH ground state levels. Since the 1720 and 1612 MHz line rest frequencies have different dependences on the fine structure constant α and the proton-electron mass ratio μ, a comparison between their measured redshifts allows one to probe changes in α and μ with cosmological time...
February 9, 2018: Physical Review Letters
Montaña Rufo, Alicia Antolín, Jesús M Paniagua, Antonio Jiménez
A comparative study was made of three methods of interpolation - inverse distance weighting (IDW), spline and ordinary kriging - after optimization of their characteristic parameters. These interpolation methods were used to represent the electric field levels for three emission frequencies (774kHz, 900kHz, and 1107kHz) and for the electrical stimulation quotient, QE , characteristic of complex electromagnetic environments. Measurements were made with a spectrum analyser in a village in the vicinity of medium-wave radio broadcasting antennas...
April 2018: Environmental Research
Alejandro Luque
We present a full electromagnetic model of streamer propagation where the Maxwell equations are solved self-consistently together with electron transport and reactions including photoionization. We apply this model to the collision of counter-propagating streamers in gaps tens of centimeters wide and with large potential differences of hundreds of kilovolts. Our results show that streamer collisions emit electromagnetic pulses that, at atmospheric pressure, dominate the radio frequency spectrum of an extended corona in the range from about 100 MHz to a few gigahertz...
October 16, 2017: Journal of Geophysical Research. Atmospheres: JGR
Kyu Been Kwon, Teyoun Kang, Hyung Seon Song, Young-Kuk Kim, Bernhard Ersfeld, Dino A Jaroszynski, Min Sup Hur
Emission of radiation from electrons undergoing plasma oscillations (POs) at the plasma frequency has attracted interest because of the existence of intriguing and non-trivial coupling mechanism between the electrostatic PO and the emitted electromagnetic wave. While broadband emission from plasma waves in inhomogeneous plasma is well known, the underlying physics of narrowband emission at the plasma frequency observed in experiments and in solar radio-bursts is obscure. Here we show that a spatially-localized plasma dipole oscillation (PDO) can be generated when electrons are trapped in a moving train of potential wells produced by the ponderomotive force of two slightly detuned laser pulses that collide in plasma and give rise to a burst of quasi-monochromatic radiation...
January 9, 2018: Scientific Reports
Kai-Huang Chen, Tsung-Ming Tsai, Chien-Min Cheng, Shou-Jen Huang, Kuan-Chang Chang, Shu-Ping Liang, Tai-Fa Young
In this study, the hopping conduction distance and bipolar switching properties of the Gd:SiOx thin film by (radio frequency, rf) rf sputtering technology for applications in RRAM devices were calculated and investigated. To discuss and verify the electrical switching mechanism in various different constant compliance currents, the typical current versus applied voltage ( I-V ) characteristics of gadolinium oxide RRAM devices was transferred and fitted. Finally, the transmission electrons' switching behavior between the TiN bottom electrode and Pt top electrode in the initial metallic filament forming process of the gadolinium oxide thin film RRAM devices for low resistance state (LRS)/high resistance state (HRS) was described and explained in a simulated physical diagram model...
December 28, 2017: Materials
Qijun Zhang, Lin Wu, Xiaozhen Fang, Mingyue Liu, Jing Zhang, Min Shao, Sihua Lu, Hongjun Mao
In order to obtain VOCs emission characteristics and emission factors from vehicle, a tunnel experiment was conducted in the Fu Gui Mountain Tunnel in Nanjing, China. The tunnel is located in the middle of city, with total length of 480m and speed limit of 50km/h. The studied vehicle fleet was composed of 87% light duty vehicles and 13% heavy duty vehicles (liquefied natural gas bus, LNGB). The emerging radio frequency identification (RFID) technology was used to divide fine vehicles type including China I, China II, China III, China IV, China V and LNGB...
May 15, 2018: Science of the Total Environment
Marissa L Weichman, Bess Vlaisavljevich, Jessalyn A DeVine, Nicholas S Shuman, Shaun G Ard, Toru Shiozaki, Daniel M Neumark, Albert A Viggiano
The chemi-ionization reaction of atomic samarium, Sm + O → SmO+ + e- , has been investigated by the Air Force Research Laboratory as a means to modify local electron density in the ionosphere for reduction of scintillation of high-frequency radio waves. Neutral SmO is a likely unwanted byproduct. The spectroscopy of SmO is of great interest to aid in interpretation of optical emission spectra recorded following atmospheric releases of Sm as part of the Metal Oxide Space Cloud (MOSC) observations. Here, we report a joint experimental and theoretical study of SmO using slow photoelectron velocity-map imaging spectroscopy of cryogenically cooled SmO- anions (cryo-SEVI) and high-level spin-orbit complete active space calculations with corrections from second order perturbation theory (CASPT2)...
December 21, 2017: Journal of Chemical Physics
Weiwei Pan, Lei Zhang, Jiaqi Zhou, Xuezong Yang, Yan Feng
The mode locking of a Raman fiber laser with an amplified spontaneous emission (ASE) pump source is investigated for performance improvement. Raman dissipative solitons with a compressed pulse duration of 1.05 ps at a repetition rate of 2.47 MHz are generated by utilizing nonlinear polarization rotation and all-fiber Lyot filter. A signal-to-noise ratio as high as 85 dB is measured in a radio-frequency spectrum, which suggests excellent temporal stability. Multiple-pulse operation with unique random static distribution is observed for the first time, to the best of our knowledge, at higher pump power in mode-locked Raman fiber lasers...
December 15, 2017: Optics Letters
Thorsten Feichtner, Silke Christiansen, Bert Hecht
The emission rate of a point dipole can be strongly increased in the presence of a well-designed optical antenna. Yet, optical antenna design is largely based on radio-frequency rules, ignoring, e.g., Ohmic losses and non-negligible field penetration in metals at optical frequencies. Here, we combine reciprocity and Poynting's theorem to derive a set of optical-frequency antenna design rules for benchmarking and optimizing the performance of optical antennas driven by single quantum emitters. Based on these findings a novel plasmonic cavity antenna design is presented exhibiting a considerably improved performance compared to a reference two-wire antenna...
November 24, 2017: Physical Review Letters
C M Raiteri, M Villata, J A Acosta-Pulido, I Agudo, A A Arkharov, R Bachev, G V Baida, E Benítez, G A Borman, W Boschin, V Bozhilov, M S Butuzova, P Calcidese, M I Carnerero, D Carosati, C Casadio, N Castro-Segura, W-P Chen, G Damljanovic, F D'Ammando, A Di Paola, J Echevarría, N V Efimova, Sh A Ehgamberdiev, C Espinosa, A Fuentes, A Giunta, J L Gómez, T S Grishina, M A Gurwell, D Hiriart, H Jermak, B Jordan, S G Jorstad, M Joshi, E N Kopatskaya, K Kuratov, O M Kurtanidze, S O Kurtanidze, A Lähteenmäki, V M Larionov, E G Larionova, L V Larionova, C Lázaro, C S Lin, M P Malmrose, A P Marscher, K Matsumoto, B McBreen, R Michel, B Mihov, M Minev, D O Mirzaqulov, A A Mokrushina, S N Molina, J W Moody, D A Morozova, S V Nazarov, M G Nikolashvili, J M Ohlert, D N Okhmat, E Ovcharov, F Pinna, T A Polakis, C Protasio, T Pursimo, F J Redondo-Lorenzo, N Rizzi, G Rodriguez-Coira, K Sadakane, A C Sadun, M R Samal, S S Savchenko, E Semkov, B A Skiff, L Slavcheva-Mihova, P S Smith, I A Steele, A Strigachev, J Tammi, C Thum, M Tornikoski, Yu V Troitskaya, I S Troitsky, A A Vasilyev, O Vince
Blazars are active galactic nuclei, which are powerful sources of radiation whose central engine is located in the core of the host galaxy. Blazar emission is dominated by non-thermal radiation from a jet that moves relativistically towards us, and therefore undergoes Doppler beaming. This beaming causes flux enhancement and contraction of the variability timescales, so that most blazars appear as luminous sources characterized by noticeable and fast changes in brightness at all frequencies. The mechanism that produces this unpredictable variability is under debate, but proposed mechanisms include injection, acceleration and cooling of particles, with possible intervention of shock waves or turbulence...
December 21, 2017: Nature
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