Showing papers on "Transverse plane published in 2021"

CASCADE3 A Monte Carlo event generator based on TMDs

Abstract: The Cascade3 Monte Carlo event generator based on Transverse Momentum Dependent (TMD) parton densities is described. Hard processes which are generated in collinear factorization with LO multileg or NLO parton level generators are extended by adding transverse momenta to the initial partons according to TMD densities and applying dedicated TMD parton showers and hadronization. Processes with off-shell kinematics within $$k_{{t}}$$ -factorization, either internally implemented or from external packages via LHE files, can be processed for parton showering and hadronization. The initial state parton shower is tied to the TMD parton distribution, with all parameters fixed by the TMD distribution.

Longitudinal and transverse spatial beam profile measurement of relativistic electron bunch by electro-optic sampling

Abstract: Electro-optic (EO) sampling is employed to measure the electric field profiles generated by a relativistic electron bunch along the propagation and in the radial directions. The longitudinal (temporal) profile is investigated by changing the time delay between the electron bunch and the pulsed probe laser, while the transverse (radial) profile is acquired by laterally shifting the path of the electron bunch. Experimental results show good agreement with three-dimensional particle-in-cell calculations. We demonstrated a promising method to simultaneously obtain the longitudinal and transverse beam sizes by utilizing the detected spatio-temporal electric field distribution around the electron bunch.

Highly efficient transverse thermoelectric devices with Re4Si7 crystals

Abstract: The principal challenges in current thermoelectric power generation modules are the availability of stable, diffusion-resistant, lossless electrical and thermal metal–semiconductor contacts that do not degrade at the hot end nor cause reductions in device efficiency. Transverse thermoelectric devices, in which a thermal gradient in a single material induces a perpendicular voltage, promise to overcome these problems. However, the measured material transverse thermoelectric efficiencies, zxyT, of nearly all materials to date has been far too low to confirm these advantages in an actual device. Here, we show that single crystals of Re4Si7, an air-stable, thermally robust, layered compound, have a transverse zxyT of 0.7 ± 0.15 at 980 K, a value that is on par with existing commercial longitudinal theremoelectrics today. Through constructing and characterizing a transverse power generation module, we prove that extrinsic losses through contact resistances are minimized in this geometry, and that no electrical contacts are needed at the hot side. This excellent transverse thermoelectric performance arises from the large, oppositely signed in-plane p-type and cross-plane n-type thermopowers. These large anisotropic thermopowers arise from thermal population of the highly anisotropic valence band and isotropic conduction band in this narrow gap semiconductor. Overall, this work establishes Re4Si7 as the “gold-standard” of transverse thermoelectrics, allowing future exploration of unique device architectures for waste heat recovery.

A Novel Dual-Polarized Continuous Transverse Stub Antenna Based on Corrugated Waveguides—Part II: Experimental Demonstration

Abstract: We present the experimental validation of the dual-mode, polarization-agile parallel-fed continuous transverse stub (CTS) antenna architecture introduced in Part I of this two-part paper. The Ka-band dual-mode CTS array described in Part I is characterized when it radiates in horizontal and vertical polarization. To this end, it is combined with two different quasi-optical beamformers operating in a quasi-transverse electromagnetic (quasi-TEM) and in a quasi-transverse electric (quasi-TE1) mode, respectively. The scanning capabilities of both multibeam antenna systems are demonstrated. The CTS array and its feed network comprising corrugated parallel-plate waveguides (CPPWs) are fabricated by additive manufacturing. Measurements show that the dual-polarized CTS antenna works between 29 and 32 GHz in a field of view of about 45°, achieving a peak gain of 31.3 dBi and very low cross polarization. These promising results pave the way for the realization of dual-circularly polarized beam-scanning antennas with application to broadband and compact Ka-band ground terminals.

Effect of transverse flow on flame spread and extinction over polyethylene-insulated wires

Abstract: The spread of flames over solid combustible surface in a transverse flow (perpendicular to the flame spread direction) is common in real fire scenarios, but has not been well quantified yet. In this paper, we systematically investigate the effect of transverse flow on flame spread and extinction over electrical wire insulation by using eight types of polyethylene (PE)-insulated wire of various configurations (core diameter; insulation thickness) and two representative core material (Copper: high-conductivity, Nickel-chrome: low-conductivity). The experiment is conducted in a combustion tunnel providing a uniform transverse flow. Results demonstrate that the flame spread rate (FSR) shows non-monotonic behavior with increasing transverse flow velocity until extinction, where four regimes can be identified with different controlling mechanisms. Flame spread faster over Copper (Cu)-core wires than that over Nickel-chrome (NiCr)-core wires, but is easier to extinguish in high flow region, revealing simultaneous dual effect of the “heat source” and “heat sink” due to wire core conduction. A theoretical model is developed based on two characteristic lengths (flame base width Wf and average gas-phase thermal length L g ¯ ), and a proposed mixed-flow velocity Vmix coupling transverse flow velocity and buoyancy-induced flow velocity. The model well predicts the experimental FSR. Moreover, an extinction limit is proposed in terms of heat loss factor Rloss as a function of strain rate am, where the coupling effects of gas-phase blow-off and condensed-phase quenching are well integrated. The present work facilitates understanding of flame spread mechanism in mixed-transverse flow condition over cylindrical fuels not only on the electric wires, but also on the branches in wildland fires.

Transverse shifts and time delays of spatiotemporal vortex pulses reflected and refracted at a planar interface

Abstract: Transverse (Hall-effect) and Goos--Hanchen shifts of light beams reflected/refracted at planar interfaces are important wave phenomena, which can be significantly modified and enhanced by the presence of intrinsic orbital angular momentum (OAM) in the beam. Recently, optical spatiotemporal vortex pulses (STVPs) carrying a purely transverse intrinsic OAM were predicted theoretically and generated experimentally. Here we consider the reflection and refraction of such pulses at a planar isotropic interface. We find theoretically and confirm numerically novel types of the OAM-dependent transverse and longitudinal pulse shifts. Remarkably, the longitudinal shifts can be regarded as time delays, which appear, in contrast to the well-known Wigner time delay, without temporal dispersion of the reflection/refraction coefficients. These results can have important implications in various problems involving scattering of localized vortex states carrying transverse OAM.

The First 3D Coronal Loop Model Heated by MHD Waves against Radiative Losses

Abstract: In the quest to solve the long-standing coronal heating problem, it has been suggested half a century ago that coronal loops could be heated by waves. Despite the accumulating observational evidence of the possible importance of coronal waves, still no 3D MHD simulations exist that show significant heating by MHD waves. Here we report on the first 3D coronal loop model heating the plasma against radiative cooling. The coronal loop is driven at the footpoint by transverse oscillations and subsequently the induced Kelvin-Helmholtz instability deforms the loop cross-section and generates small-scale structures. Wave energy is transfered to smaller scales where it is dissipated, overcoming the internal energy losses by radiation. These results open up a new avenue to address the coronal heating problem.

Study of Proton, Deuteron, and Triton at 54.4 GeV

Abstract: Transverse momentum spectra of proton, deuteron, and triton in gold-gold (Au-Au) collisions at 544 GeV are analyzed in different centrality bins by the blast wave model with Tsallis statistics The model results are approximately in agreement with the experimental data measured by STAR Collaboration in special transverse momentum ranges We extracted the kinetic freeze-out temperature, transverse flow velocity, and freeze-out volume from the transverse momentum spectra of the particles It is observed that the kinetic freeze-out temperature is increasing from the central to peripheral collisions However, the transverse flow velocity and freeze-out volume decrease from the central to peripheral collisions The present work reveals the mass dependent kinetic freeze-out scenario and volume differential freeze-out scenario in collisions at STAR Collaboration In addition, parameter characterizes the degree of nonequilibrium of the produced system, and it increases from the central to peripheral collisions and increases with mass

Unconventional four-terminal thermoelectric transport due to inelastic transport: Cooling by transverse heat current, transverse thermoelectric effect, and Maxwell demon

Abstract: We show that, in mesoscopic four-terminal thermoelectric devices with two electrodes (the source and the drain) and two heat baths, inelastic-scattering processes can lead to unconventional thermoelectric transport. The source (or the drain) can be cooled by passing a thermal current between the two heat baths, with no net heat exchange between the heat baths and the electrodes. This effect, termed ``cooling by transverse heat current,'' is a mesoscopic heat drag effect. In addition, there is a transverse thermoelectric effect where electrical current and power can be generated by a transverse temperature bias (i.e., the temperature bias between the two heat baths). This transverse thermoelectric effect originates from inelastic-scattering processes and may have advantages for improved figures of merit and power factor due to spatial separation of charge and heat transport. We study the Onsager current-affinity relations, the linear-response transport properties, and the transverse thermoelectric figure of merit of the four-terminal thermoelectric devices for various system parameters. We find that the figures of merit are optimized in different parameter regions for the transverse and the (conventional) longitudinal thermoelectric effects, respectively. Meanwhile, the maximum figure of merit for the transverse thermoelectric effect is higher than the figure of merit for the conventional longitudinal thermoelectric effect. In addition, we investigate the efficiency and power of the cooling by the transverse heat current effect in both linear and nonlinear transport regimes. Finally, we demonstrate that, by exploiting the inelastic transport in the quantum-dot four-terminal systems, a type of Maxwell demon can be realized using nonequilibrium heat baths.

Analysis and Design of Bessel Beam Launchers: Transverse Polarization

Abstract: In this communication, we present a theoretical analysis, design, and fabrication of a limited-diffractive planar Bessel beam launcher, that exhibits a zeroth-order Bessel profile in the transverse electric field component with respect to the ${z}$ -propagation axis. The launcher is designed by synthesizing a finite zeroth-order, first kind Hankel aperture distribution, polarized along a fixed polarization unit vector. The field radiated by such an aperture distribution is derived by following an approximate model based on the geometric theory of diffraction, thus allowing to highlight the relevant wave constituents involved in transverse Bessel beam generation, also including the effect of aperture truncation on the radiated beam. Moreover, the theoretical analysis has been profitably applied to the design of a circular-polarized planar transverse Bessel beam launcher by means of a slotted radial waveguide. A prototype of right-handed circular polarized (RHCP) transverse Bessel beam launcher has then been fabricated at $f = 30$ GHz. The measured transverse electric field component shows a satisfactory agreement with full-wave numerical simulations.

The First 3D Coronal Loop Model Heated by MHD Waves against Radiative Losses

Abstract: In the quest to solve the long-standing coronal heating problem, it has been suggested half a century ago that coronal loops could be heated by waves. Despite the accumulating observational evidence of the possible importance of coronal waves, still no 3D MHD simulations exist that show significant heating by MHD waves. Here we report on the first 3D coronal loop model heating the plasma against radiative cooling. The coronal loop is driven at the footpoint by transverse oscillations and subsequently the induced Kelvin-Helmholtz instability deforms the loop cross-section and generates small-scale structures. Wave energy is transfered to smaller scales where it is dissipated, overcoming the internal energy losses by radiation. These results open up a new avenue to address the coronal heating problem.

Radial Two-Dimensional Ion Crystals in a Linear Paul Trap.

Abstract: We experimentally study two-dimensional (2D) Coulomb crystals in the ``radial-2D'' phase of a linear Paul trap. This phase is identified by a 2D ion lattice aligned entirely with the radial plane and is created by imposing a large ratio of axial to radial trapping potentials. Using arrays of up to 19 $^{171}{\mathrm{Yb}}^{+}$ ions, we demonstrate that the structural phase boundaries of such crystals are well described by the pseudopotential approximation, despite the time-dependent ion positions driven by intrinsic micromotion. We further observe that micromotion-induced heating of the radial-2D crystal is confined to the radial plane. Finally, we verify that the transverse motional modes, which are used in most ion-trap quantum simulation schemes, are well-predictable numerically and remain decoupled and cold in this geometry. Our results establish radial-2D ion crystals as a robust experimental platform for realizing a variety of theoretical proposals in quantum simulation and computation.

Novel higher-order zigzag theory for analysis of laminated sandwich beams:

Abstract: In the present work, a new higher-order zigzag theory is proposed for the analysis of laminated sandwich beams under static and free vibration conditions. Fourth-order in-plane and transverse displ...

Spin-orbit coupling within tightly focused circularly polarized spatiotemporal vortex wavepacket

Abstract: Spin-orbital coupling and interaction as intrinsic light fields characteristics have been extensively studied. Previous studies involve the spin angular momentum (SAM) carried by circular polarization and orbital angular momentum (OAM) associated with a spiral phase wavefront within the beam cross section, where both the SAM and OAM are in parallel with the propagation direction. In this work, we study a new type of spin-orbital coupling between the longitudinal SAM and the transverse OAM carried by a spatiotemporal optical vortex (STOV) wavepacket under tight focusing condition. Intricate spatiotemporal phase singularity structures are formed when a circularly polarized STOV wavepacket is tightly focused by a high numerical aperture objective lens. For the transversely polarized components, phase singularity orientation can be significantly tilted away from the transverse direction towards the optical axis due to the coupling between longitudinal SAM and transverse OAM. The connection between the amount of rotation and the temporal width of the wavepacket is revealed. More interestingly, spatiotemporal phase singularity structure with a continuous evolution from longitudinal to transverse orientation through the wavepacket is observed for the longitudinally polarized component. These exotic spin-orbit coupling phenomena are expected to render new effects and functions when they are exploited in light matter interactions.

On dispersion of solute in a hydromagnetic flow between two parallel plates with boundary absorption

Abstract: It is well known that the widely applied Taylor diffusion model predicts the longitudinal distribution of tracers. Some recent studies indicate that the transverse concentration distribution is highly significant for large dispersion times. The present study describes an analytical approach to explore the two-dimensional concentration dispersion of a solute in the hydromagnetic laminar flow between two parallel plates with boundary absorption. The analytical expressions for the transverse concentration distribution and the mean concentration distribution of the tracers up to second-order approximation are derived using Mei's homogenization technique. The effects of the Peclet number and Hartmann number on the Taylor dispersivity are shown. It is also observed how the transverse and longitudinal mean concentration distributions are influenced by the magnetic effect, dispersion times, and boundary absorption. It is remarkable to note that the boundary absorption creates a large non-uniformity on the transverse concentration in a hydromagnetic flow between two parallel plates.

Control of the intensity distribution along the light spiral generated by a generalized spiral phase plate

Abstract: This paper proposes a method for shaping a light spiral with the desired intensity and phase distributions based on the addition of an angular-dependent amplitude distribution to the phase transmission function of a generalized spiral phase plate. An expression for the amplitude distribution of the illuminating beam, which provides a given intensity distribution in the focal plane along the light spiral, was derived, with the numerically and experimentally obtained results confirming the analytical calculations. The ability to control the phase and intensity gradient along the generated light curves allows one to shape the desired transverse energy flow distribution in the focal plane, which is important for optical manipulation of nano- and microparticles as demonstrated by the laser guiding of trapped 5 µm polystyrene microspheres.

Model test and discrete element method simulation of shield tunneling face stability in transparent clay

Abstract: The stability of the shield tunneling face is an extremely important factor affecting the safety of tunnel construction. In this study, a transparent clay with properties similar to those of Tianjin clay is prepared and a new transparent clay model test apparatus is developed to overcome the “black box” problem in the traditional model test. The stability of the shield tunneling face (failure mode, influence range, support force, and surface settlement) is investigated in transparent clay under active failure. A series of transparent clay model tests is performed to investigate the active failure mode, influence range, and support force of the shield tunneling face under different burial depth conditions, whereas particle flow code three-dimensional numerical simulations are conducted to verify the failure mode of the shield tunneling face and surface settlement along the transverse section under different burial depth conditions. The results show that the engineering characteristics of transparent clay are similar to those of soft clay in Binhai, Tianjin and satisfy visibility requirements. Two types of failure modes are obtained: the overall failure mode (cover/diameter: C/D ⩽ 1.0) and local failure mode (C/D ⩾ 2.0). The influence range of the transverse section is wider than that of the longitudinal section when C/D ⩾ 2.0. Additionally, the normalized thresholds of the relative displacement and support force ratio are 3%–6% and 0.2–0.4, respectively. Owing to the cushioning effect of the clay layer, the surface settlement is significantly reduced as the tunnel burial depth increases.

Effect of Gust Width on Flat-Plate Response in Large Transverse Gust

Abstract: The split velocity method was applied to study the response of a finite flat-plate wing with an aspect ratio of four encountering a large transverse gust with various gust widths. The gust is model...

Detection of circumferential cracks in heat exchanger tubes using pulsed eddy current testing

Abstract: Heat exchanger tubes in industrial pressure vessels typically require periodic inspection, and detection of circumferential cracks is one of the foremost issues. In this study, the pulsed eddy current method was used for the detection, and new types of probes were designed. Transverse probes were designed to render the eddy currents perpendicular to circumferential cracks to improve detection sensitivity, and the corresponding numerical simulations showed that the eddy currents were approximately perpendicular to the circumferential cracks along more than half of the tube circumference. Thus, two probes could cover the entire circumference for more economical inspection to be achieved. The experiments were performed on copper and steel tubes. The results show that when compared to longitudinal probes, the designed transverse probes significantly improved the detection sensitivity towards circumferential cracks. Particularly, the effectiveness of the proposed method is shown regarding detection of deep defects with good sensitivity in steel tubes without saturation magnetization.

Transverse oscillation of a coronal loop induced by a flare-related jet

Abstract: Context. Kink oscillations in coronal loops are ubiquitous, and we apply the observed parameters of oscillations to estimate the magnetic field strength of the loops.Aims. In this work, we report our multiwavelength observations of the transverse oscillation of a large-scale coronal loop with a length of ≥350 Mm. The oscillation was induced by a blowout coronal jet, which was related to a C4.2 circular-ribbon flare (CRF) in active region 12434 on 2015 October 16. We aim to determine the physical parameters in the coronal loop, including the Alfven speed and the magnetic field strength.Methods. The jet-induced kink oscillation was observed in extreme ultraviolet (EUV) wavelengths by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Line-of-sight magnetograms were observed by the Helioseismic and Magnetic Imager (HMI) on board the SDO. We took several slices along the loop to assemble time-distance diagrams and used an exponentially decaying sine function to fit the decaying oscillation. The initial amplitude, period, and damping time of kink oscillations were obtained. Coronal seismology of the kink mode was applied to estimate the Alfven speed and the magnetic field strength in the oscillating loop. In addition, we measured the magnetic field of the loop through nonlinear force-free field (NLFFF) modeling using the flux rope insertion method.Results. The oscillation is most pronounced in AIA 171 and 131 A. The oscillation is almost in phase along the loop with a peak initial amplitude of ∼13.6 Mm, meaning that the oscillation belongs to the fast standing kink mode. The oscillation lasts for ∼3.5cycles with an average period of ∼462 s and an average damping time of ∼976 s. The values of τ /P lie in the range of 1.5–2.5. Based on coronal seismology, the Alfven speed in the oscillating loop is estimated to be ∼1210 km s−1 . Two independent methods are applied to calculate the magnetic field strength of the loop, resulting in 30–43 G using coronal seismology and 21–23 G using NLFFF modeling.Conclusions. The magnetic field strength estimated using two different approaches are on the same order of magnitude, which confirms the reliability of coronal seismology by comparing with NLFFF modeling.

Fiber in-line Mach-Zehnder interferometer for simultaneous measurement of transverse loading and temperature based on multi-core fiber

Abstract: A fiber in-line Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated for simultaneously measuring transverse loading and temperature. The MZI is fabricated by simply splicing a segment multicore fiber (MCF) with two short sections of multimode fibers (MMFs). The sensing principle is theoretically analyzed and the transverse loading and temperature characteristics of the sensor are investigated in experiment. The results show that the multimode interference among the center core mode (CCM), the cladding modes (CM) and outer core mode (OCM) of the MCF enables the sensor to realize the measurements of transverse loading and temperature. The transmission spectra will shift when the external transverse loading and temperature variation, and different spectral responses of the resonant dips are observed, which indicates that the sensor can implement the simultaneous transverse loading and temperature measurement by monitoring the wavelength changes of two resonant dips. The obtained sensitivities of transverse pressure and temperature can reach up to −165 pm/N and 45 pm/°C, respectively. The proposed sensor has the potential application in the fields where both temperature and transverse loading measurements are required.

Dynamic Characteristic Analysis of Rotating Blade With Transverse Crack—Part I: Modeling, Modification, and Validation

Abstract: This study aims at the systematical improvement and comparative analysis of analytical crack models for the rotating blade. Part I of this study focuses on analytical modeling, model modification, and model validation of transverse crack for the rotating blade. The most widely applied analytical crack models for the rotating blade are reviewed and compared, and then their limitations are discussed. It is indicated that the conventional analytical crack models suffer from low physical interpretability and vibration prediction accuracy. By considering these limitations of conventional analytical crack models, model modification is performed to enhance the physical meaning and improve the accuracy. First, the stress-based breathing crack model is modified by direct calculation of the breathing function based on the theory of linear elastic fracture mechanics and resetting the correction factor of centrifugal stiffening stiffness. Second, the vibration-based breathing crack models, including bilinear breathing crack model and cosine breathing crack model, are modified by introducing the coupling effect between bending stress and centrifugal stress based on the stress state at the blade crack section. The additional bending moment induced by the blade part outside the crack section is considered in all analytical models. The modified crack models’ validity is verified by comparing vibration responses obtained by the modified crack models, the finite element contact crack model, and the conventional crack models. The comparative results suggest that the modified models promote the physical interpretability and improve the vibration prediction accuracy of analytical crack models.