Angular Phase Research Articles

Effect of Age on Thoracic, Lumbar, and Pelvis Coordination During Trunk Flexion and Extension.

The purpose of this study was to investigate normative and age-related differences in trunk and pelvis kinematics and intersegmental coordination during sagittal plane flexion-extension. Trunk and pelvis kinematics were recorded while 76 participants performed a maximal range of motion task in the sagittal plane. Cross-correlation was calculated to determine the phase lag between adjacent segment motion, and coupling angles were calculated using vector coding and classified into one of 4 coordination patterns: in-phase, antiphase, superior, and inferior phase. A 2-way mixed-model multivariate analysis of variance was used to compare lumbar spine and pelvis angular kinematics, phase lags, and cross-correlation coefficients between groups. Young participants exhibited greater trunk range of motion compared with middle-aged participants. The lumbar spine and pelvis were predominantly rotating with minimum phase lag during flexion and extension movement for both age groups, and differences in coordination between the groups were seen during hyperextension and return to upright position. In conclusion, middle-aged adults displayed lower range of motion but maintained similar movement patterns to young adults, which could be attributed to protective mechanisms. Healthy lumbar and pelvis movement patterns are important to understand and need to be quantified as a baseline, which can be used to develop rehabilitation protocols for individuals with spinal ailments.

Experimental study of the shear flow effect on tidal turbine blade loading variation

Tidal turbine arrays are planed to be installed in areas with strong currents where the flow can often be sheared throughout the water column. To study the shear flow effects on tidal turbine, four vertical velocity profiles are generated in a flume tank and are imposed to a three-bladed horizontal axis turbine model. Results show that the sheared velocity profiles do not impact the turbine average performance but are responsible for an increase of blade root streamwise load variations. Blade root streamwise load is moreover linked to the turbine rotational frequency and its harmonics. The velocity perceived by the blades during their rotation is estimated over the rotor area and is compared to the angular phase average of the streamwise load measured on the blades. The phase average of the load and the velocity perceived by the blades are highly correlated even if a varying phase lag has been noticed between these two quantities. This phase lag is dependent on the rotational speed of the turbine, on the incoming flow shear, and is probably caused by the turbine induction effects. This experimental study is a first step to understand the effect of shear velocity profiles on tidal turbines better.

Revealing the Orbital Angular Momentum Spectrum and Correlation Phase of Optical Vortices With Wander Perturbations and Spiral Offsets

Controlling the orbital angular momentum (OAM) spectrum, as well as the modulus and phase of the first-order correlation function of a vortex beam produced by a dynamic wander source, is critical for the use of OAM photons in turbulent environments. Based on a derived analytical formula for the first-order correlation function of the light field, a theoretical model and an experimental approach are proposed for synthesizing and detecting complex wander vortex beams in the laboratory. Wander perturbations and spiral phase offsets are considered. The correlation phase and OAM spectrum of complex wander vortex beams are measured with a single spatial light modulator (SLM). The experimental results agree with the theoretical simulations and show that, given a limited region of interest, wander perturbations broaden the OAM spectrum asymmetrically with respect to the initial input mode, with a higher proportion of lower ordered non-signal modes than higher ordered modes. For a large spiral phase offset, the main peak of the OAM spectrum shifts away from the signal mode and toward a lower ordered side mode. Generation and measurement strategies have significant potential for free-space communication and remote sensing in turbulent environments.

UNINTERRUPTED LOAD TRANSFER BETWEEN TWO DISTRIBUTION FEEDERS WITH DIFFERENT POWER SOURCES

ABSTRACT: This article shows the analysis for load transfer without interruption between two 23 kV distribution feeders. This procedure is not common in this type of system and requires paying primary attention to the characteristics of the electrical network for its application. The distribution circuits discussed here have their own power substation with different voltage levels. The information obtained from a state estimator, the contingency conditions, the electrical parameters of impedances and network configuration allow to carry out the simulation of the load transfer with the Alternative Transients Program software. From the simulation it is shown that load transfer without interruption is possible as long as certain operating conditions are met in the power and distribution networks. The dependence of the transfer on the voltage levels, angular phase shift of voltages and strength of the electrical network is shown, represented by its thevenin impedance at the interconnection point. The results found from the simulation indicate that the success of the interconnection is mainly a function of the electrical strength of the power substations and the phase sequence of the power transformer at the load transfer point. Certain percentages of variation of voltage and currents of the feeders are defined that must not be exceeded. The operational aspects proposed here serve as a basis to have a general interconnection procedure between distribution feeders where special attention is required in the continuity of the service due to the high expectation in the satisfaction of the user of the electrical network. Keywords: feeder, state estimator, medium voltage, power system, load transferring.

Angular-field magnetic phase diagram of b-plane at 4 K of YAlGe-type TbAlGe with zigzag-chain

Orthorhombic YAlGe-type TbAlGe is expected to have an interesting magnetic anisotropy due to zigzag chains of the Tb ions. We have grown the single crystal for the first time and measured the AC magnetic susceptibility and specific heat from 1.3 K to 60 K, and the vector magnetization for the b-plane up to 7 T at 4 K. The specific heat and AC magnetic susceptibility indicate that there are two antiferromagnetic transitions at T N1 = 38 K and TN2 = 7.6 K, where the transition at T N2 is first-order like. The magnetization curve at 4 K for the a-axis shows a large hysteresis, and metamagnetic transition appears at H 1 = 1.6 T in the field increasing process, and another metamagnetic transition at H2 = 3.5 T in addition to H 1 in the decreasing field process. The magnetization curves of the b- and c-axis are linear up to 7 T. The measurement of vector magnetization at 4 K reflects the hysteresis of the magnetization curve, and there is a large hysteresis. From this vector magnetization measurement, we have made the angular magnetic field phase diagram at 4 K for the b-plane. In this phase diagram, there are phase lines that cannot be obtained by ordinary magnetization measurement.

Phase-matching condition in rotatory nonlinear optics

Polarization rotation of light beams, such as optical activity and Faraday rotation, is a natural effect that generates the rotation of the polarized direction of light and some undiscovered characteristics in nonlinear optics. In our previous study, we theoretically investigated the second-harmonic generation process in rotatory nonlinear optics and found an unprecedented phase-matching condition. Here, the optical phase-matching condition in the second-harmonic generation with rotatory polarization is theoretically analyzed and associated with the angular rotation-induced phases of mixing waves, which goes beyond the previous theoretical analysis. Moreover, the Pancharatnam-Berry topological phase was found to be periodically generated and could be employed to compensate for the mismatched phase during nonlinear optical interaction. Possible experimental schemes were proposed and discussed. This work provides not only a universal and flexible (quasi-) phase-matching condition for the rotatory nonlinear optics existing in most nonlinear optical media but may also inspire the development of modern photonics.

Quasi-perfect vortices generated by Pancharatnam-Berry phase metasurfaces for optical spanners and OAM communication

Optical vortex (OV) can be used in the fields of optical manipulation and optical communication because of its inherent orbital angular momentum (OAM). The size of the OV ring increases with the correlated topological charge (TC), making the OV with large TC not suitable for optical rotation and short-distance communication. Perfect vortex (PV) has attracted much attention due to that its optical transmission profile is almost independent of TC. In this manuscript, we proposed a method to generate quasi- perfect vortices (Q-PVs) by Pancharatnam–Berry (PB) phase metasurfaces, the so-called Q-PV can be regarded as an annularly focused optical vortex whose focal ring in the focal plane has an angular phase gradient. It has a similar property to PV in that its light profile hardly changes with TC in the focal plane. We demonstrated that the Q-PV can be used for optical spanners that particles are trapped and rotated on the specific orbit. Non-coaxial and coaxial Q-PV arrays were further generated for OAM communication applications. We believe that the proposed Q-PVs has potential applications in optical manipulation and optical communication.

Angular birefringence phase matching behaviour of Lithium Triborate (LBO) crystal for second harmonic generation in broad wavelength range

Second Harmonic Generation (SHG) is a nonlinear optical process in which the frequency of the incident radiation gets doubled. There are various types of applications of SHG such as ultra-short pulse measurement, high resolution optical microscopy, characterization of the structure of 2D materials and its physical properties like the thickness of interlayer stacking, stacking angle between different layers, the grain boundary etc. It has also been used to determine the structure of Langmuir-Blodgett films of low symmetry. For SHG, various commercial nonlinear optical (NLO) crystals are generally used. Lithium Triborate (LBO) is one of the best NLO material among them due to its wide transparency range (160–2600 nm), high damage threshold (19 GW/cm2 @1064 nm, 1 ns) and high second order nonlinear coefficient. It has also the ability to establish birefringence phase matching condition for efficient SHG for different wavelengths. The crystal can be used for generation for SHG in broad wavelength range through angular phase matching method. For this, in this work detail investigation has been made to find out the optimum wavelength range that can be used for efficient SHG. This has been done by finding the variation of phase matching angle, second order nonlinearity etc. with respect to wavelength using the SNLO software. Both Type I and Type II phase matching has been considered for various planes of the crystal.

Retrieval of complex angle-dependent transition dipoles by using macroscopic high harmonics generated from aligned N2 molecules

The high-order harmonic generation (HHG) by aligned molecules is the consequence of coherent summation of the complex laser-induced dipoles according to the alignment distribution of the molecules. Using the single-molecule quantitative rescattering (QRS) model with the known alignment distribution and the strong-field ionization of fixed-in-space molecules, the complex angle-dependent photorecombination transition dipoles between the ground and ionic states of molecules can be retrieved from the single-molecule HHG. However, such retrieval does not consider the real experimental conditions, such as the propagation of HHG in the medium and the inaccurate measurement of the probe intensity and the alignment degree. Here we propose a method to retrieve the complex angle-dependent molecular frame transition dipoles between the highest occupied molecular orbital (HOMO) and the ionic states of N2 molecules from the macroscopic HHG of aligned molecules. In this method, the complex transition dipole is expanded with Legendre polynomials, and the HHG is expressed as a function of the modulus and phase of the complex expansion coefficients. The complex expansion coefficients can be determined by fitting the HHG data, then the angle-dependent amplitude and phase of the complex transition dipole can be obtained. We show that the angle-dependent amplitude and phase of the transition dipoles for each individual harmonic can be successfully retrieved at both low and high probe intensity and degrees of alignment. Then we show the inaccuracy of the retrieved angular dependence amplitude and phase due to the uncertainty of the probe intensity and alignment degree. As the probe intensity increases, which is usually not measured precisely in the experiment, HOMO-1 may also contribute to HHG, we thus compare the retrieved amplitude and phase of the transition dipole with or without HOMO-1’s contribution to HHG.

PERG adaptation for detection of retinal ganglion cell dysfunction in glaucoma: a pilot diagnostic accuracy study

It has been previously demonstrated that the adaptive phase changes of steady-state pattern electroretinogram (SS-PERG), recorded during 4-min presentation of patterned stimuli, are reduced in glaucoma suspects and patients compared to normal subjects. Our study aims at testing the hypothesis that adaptive changes of SS-PERG, recorded using the novel optimized Next Generation PERG (PERGx) protocol, differ between glaucoma patients and controls. In this pilot cross-sectional study, we included 28 glaucoma patients and 17 age-matched normal subjects. Both patients and controls underwent a full ophthalmologic examination, visual field testing, OCT and PERGx. The PERGx signal was sampled over 2 min (providing 1 noise and 9 signal packets) in response to alternating gratings generated on an OLED display. PERGx amplitude and phase were analyzed to quantify adaptive changes over recording time. Receiver operating characteristic (ROC) curves were used to study the diagnostic accuracy of PERGx parameters in distinguishing glaucoma patients from normal subjects. PERGx amplitude and phase data showed declining trends in both groups. PERGx amplitude slope and grand-average vector amplitude and phase were significantly different in patients compared to controls (p < 0.01), whereas phase angular dispersion was greater in patients but not significantly different between the two groups. The area under the ROC curves were 0.87 and 0.76 for PERGx amplitude slope and grand-average vector amplitude, and 0.62 and 0.87 for PERGx angular dispersion and grand-average vector phase, respectively. The PERGx paradigm resulted highly accurate in detecting the reduction of amplitude adaptive changes in glaucoma patients, presumably due to the loss of functional retinal ganglion cell autoregulation. Thus, PERG adaptation, recorded by this new protocol, might be helpful in the identification and diagnosis of early glaucomatous dysfunction.

Angular momentum redirection phase of vector beams in a non-planar geometry

Abstract An electric field propagating along a non-planar path can acquire geometric phases. Previously, geometric phases have been linked to spin redirection and independently to spatial mode transformation, resulting in the rotation of polarisation and intensity profiles, respectively. We investigate the non-planar propagation of scalar and vector light fields and demonstrate that polarisation and intensity profiles rotate by the same angle. The geometric phase acquired is proportional to j = ℓ + σ, where ℓ is the topological charge and σ is the helicity. Radial and azimuthally polarised beams with j = 0 are eigenmodes of the system and are not affected by the geometric path. The effects considered here are relevant for systems relying on photonic spin Hall effects, polarisation and vector microscopy, as well as topological optics in communication systems.

Optical parametric generation in biaxial KTA crystal under pumping by YAG:Nd laser in arbitrary directions

Herein, on the basis of expressions for the refractive indices of isonormal waves, the possibility of performing collinear phase matching for optical parametric generation in arbitrary directions of a biaxial KTA crystal under pumping by radiation of a YAG:Nd laser is analyzed. The tuning curves that determine the tuning range of the signal and idler for type-I and II-type phase-matching and arbitrary angles θ and φ in cases where the tuning is carried out along the angle θ at a fixed angle φ and vice versa are calculated. The effective nonlinear coefficient is determined. It is shown that their maximum value is achieved аt a polar angle θ = 90° and type-II phase-matching. For the case of generation of eye-safe radiation the spectral and angular phase matching widths were estimated, as well as gain widths of KTA-OPO under monochromatic pumping.

Lower limb joint angular phase plane coordination analysis on standard maximum vertical jump

Lower limb joint angular phase plane coordination analysis on standard maximum vertical jump

Measurement of the flux-averaged inclusive charged-current electron neutrino and antineutrino cross section on argon using the NuMI beam and the MicroBooNE detector

We present a measurement of the combined νe+ν¯e flux-averaged charged-current inclusive cross section on argon using data from the MicroBooNE liquid argon time projection chamber (lartpc) at Fermilab. Using the off-axis flux from the NuMI beam, MicroBooNE has reconstructed 214 candidate νe+ν¯e interactions with an estimated exposure of 2.4×1020 protons on target. Given the estimated purity of 38.6%, this implies the observation of 80 νe+ν¯e events in argon, the largest such sample to date. The analysis includes the first demonstration of a fully automated application of a dE/dx-based particle discrimination technique of electron- and photon-induced showers in a lartpc neutrino detector. The main background for this first νe analysis is cosmic ray contamination. Significantly higher purity is expected in underground detectors, as well as with next-generation reconstruction algorithms. We measure the νe+ν¯e flux-averaged charged-current total cross section to be 6.84±1.51(stat)±2.33(sys)×10−39 cm2/nucleon, for neutrino energies above 250 MeV and an average neutrino flux energy of 905 MeV when this threshold is applied. The measurement is sensitive to neutrino events where the final state electron momentum is above 48 MeV/c, includes the entire angular phase space of the electron, and is in agreement with the theoretical predictions from genie and nuwro. This measurement is also the first demonstration of electron-neutrino reconstruction in a surface lartpc in the presence of cosmic-ray backgrounds, which will be a crucial task for surface experiments like those that comprise the short-baseline neutrino program at Fermilab.10 MoreReceived 11 January 2021Accepted 21 June 2021DOI:https://doi.org/10.1103/PhysRevD.104.052002Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNeutrino interactionsTechniquesNeutrino detectorsParticle interactionsTime-projection chambersParticles & Fields

Violation of Boltzmann Equipartition Theorem in Angular Phonon Phase Space Slows down Nanoscale Heat Transfer in Ultrathin Heterofilms.

Heat transfer through heterointerfaces is intrinsically hampered by a thermal boundary resistance originating from the discontinuity of the elastic properties. Here, we show that with shrinking dimensions the heat flow from an ultrathin epitaxial film through atomically flat interfaces into a single crystalline substrate is significantly reduced due to violation of Boltzmann equipartition theorem in the angular phonon phase space. For films thinner than the phonons mean free path, we find phonons trapped in the film by total internal reflection, thus suppressing heat transfer. Repopulation of those phonon states, which can escape the film through the interface by transmission and refraction, becomes the bottleneck for cooling. The resulting nonequipartition in the angular phonon phase space slows down the cooling by more than a factor of 2 compared to films governed by phonons diffuse scattering. These allow tailoring of the thermal interface conductance via manipulation of the interface.

Experimental study on the oil production characteristics during the waterflooding of different types of reservoirs in Ordos Basin, NW China

Waterflooding experiments were conducted in micro-models (microscopic scale) and on plunger cores from low permeability, extra-low permeability and ultra-low permeability reservoirs in the Ordos Basin under different displacement pressures using the NMR techniques to find out pore-scale oil occurrence state, oil production characteristics and residual oil distribution during the process of waterflooding and analyze the effect of pore structure and displacement pressure on waterflooding efficiency. Under bound water condition, crude oil mainly occurs in medium and large pores in the low-permeability sample, while small pores and medium pores are the main distribution space of crude oil in extra-low permeability and ultra-low permeability samples. During the waterflooding, crude oil in the medium and large pores of the three types of samples are preferentially produced. With the decrease of permeability of the samples, the waterflooding front sequentially shows uniform displacement, network displacement and finger displacement, and correspondingly the oil recovery factors decrease successively. After waterflooding, the residual oil in low-permeability samples is mainly distributed in medium pores, and appears in membranous and angular dispersed phase; but that in the extra-low and ultra-low permeability samples is mainly distributed in small pores, and appears in continuous phase formed by a bypass flow and dispersed phase. The low-permeability samples have higher and stable oil displacement efficiency, while the oil displacement efficiency of the extra-low permeability and ultra-low permeability samples is lower, but increases to a certain extent with the increase of displacement pressure.

Weak and Strong Interaction of Excitation Kinks in Scalar Parabolic Equations

Motivated by studies of the Greenberg-Hastings cellular automata (GHCA) as a caricature of excitable systems, in this paper we study kink-antikink dynamics in the perhaps simplest PDE model of excitable media given by the scalar reaction diffusion-type theta -equations for excitable angular phase dynamics. On the one hand, we qualitatively study geometric kink positions using the comparison principle and the theory of terraces. This yields the minimal initial distance as a global lower bound, a well-defined sequence of collision data for kinks- and antikinks, and implies that periodic pure kink sequences are asymptotically equidistant. On the other hand, we study metastable dynamics of finitely many kinks using weak interaction theory for certain analytic kink positions, which admits a rigorous reduction to ODE. By blow-up type singular rescaling we show that distances become ordered in finite time, and eventually diverge. We conclude that diffusion implies a loss of information on kink distances so that the entropic complexity based on positions and collisions in the GHCA does not simply carry over to the PDE model.

Sub-terahertz vortex beam generation using a spiral metal reflector.

We demonstrate sub-terahertz vortex beam generation using a spiral metal reflector that can be used for both polarizations. A vortex beam is a ring-shaped beam that possesses sub-wavelength null in the center formed by angular phase variation. While the sub-terahertz vortex beams have gained increasing attention for a wide range of applications in sensing and communications, techniques for generating them are still accompanied by challenges. For example, the use of a phase plate, which is common in the optical regime, suffers from intrinsic losses of dielectric materials in the sub-terahertz regime. Moreover, holographic diffraction gratings, which could replace transmissive components, are inefficient and sensitive to the polarization. To reconcile these challenges, here we design a reflector type metal component with a spiral surface shape. We firstly derive a direct equation to design its shape. We then experimentally validate the design by mapping the radiation pattern of a vortex beam for the WR10 frequency band (75 to 110 GHz) in both of the orthogonal polarizations. The result confirms an inexpensive and versatile approach to generate a vortex beam in the sub-terahertz regime.

Angular vortex phase diagram in YBa2Cu3O7 films with c-axis correlated pinning centers

High temperature superconductors (HTSCs) exhibit rich vortex phases under the influence of nanoscale pinning centers, and complicated configurations and behavior of vortices are realized by anisotropic vortex pinning, vortex interaction, and line tension. To understand the behavior and configurations of vortices, YBa2Cu3O7 films containing self-organized nanorods (BaSnO3, BaZrO3, BaHfO3) were prepared, and the critical current density and the resistivity were measured for varying angles between the nanorods (//c-axis) and the magnetic field (θ) in the temperatures of 65–90 K. The trapping angle of the strong nanorod (θ ts) determines the vortex phase boundary in the magnetic field lower than the matching field (B< B ϕ). While the large c-axis J c peak and the resistivity dip are observed for θ< θ ts due to the vortex accommodation on the nanorods, the vortices for θ> θ ts are pinned by the matrix uncorrelated defects and/or the ab-plane pinning centers. In the magnetic field higher than B ϕ(B> B ϕ), the weak matrix c-axis correlated defects such as twin boundaries accommodate vortices at the angles smaller than the trapping angle of the matrix c-axis correlated defect. Although the matrix c-axis correlated defects do not pin the matrix-vortices for the larger angles, the matrix-vortices are pinned by the vacant nanorod portions that appear due to the magnetic field tilt. This vortex retrapping results in the off-axis J c peak and the off-axis resistivity dip. Thus, the weak pinning by matrix defects, the cage potential, and the vortex retrapping as well as the strong nanorod pinning determine the angular vortex phase of the HTSCs containing c-axis correlated pinning centers.

Photoionization dynamics of Ar trapped in a fullerene anion: Coulomb confinement resonances in 2s subshell and its impact on the 3s subshell

The photoionization dynamics of the inner subshell of an endohedral anion, using relativistic random phase approximation (RRPA), is investigated. The charged nature of the fullerene induces Coulomb confinement resonances (CCRs) not only on the 2s cross-section but also on other dynamical attributes such as angular distribution asymmetric parameter, phase shift, and time delay of the same subshell. More importantly, we find that the 2s CCRs resurrect confinement resonances into the photoionization dynamics of 3s ionization channels at energies far away from the 3s threshold. The impacts of the revivification of these resonances on the 3s cross-section, phase shift, and time delay are explored in this work.