Calculated Phase Shifts Research Articles

Limits on an improved action for contact effective field theory in two-body systems

We consider a possible resummation of subleading effects in two-body systems with a large scattering length as described by a short-range effective field theory (EFT). In particular, we investigate the consequences of a resummation of part of the range corrections. Explicit calculations of the two-body phase shifts and charge form factor indicate that, except for extreme choices, resummations do not alter the convergence of the EFT expansion and are often beneficial at the lowest orders. We have considered the expansion when the regulator cutoff is removed as well as when it is finite, and find that the cutoff is not an important factor for resummations. Our results connect with other works where the partial resummation is induced by potentials with finite cutoffs or interaction ranges.

Complex scaling calculation of phase shifts for positron collisions with positive ions

Complex scaling calculation of phase shifts for positron collisions with positive ions

Investigation of the effect of circadian rhythm on the performances of NBA teams

ABSTRACT Professional athletes competing in the NBA are frequently exposed to time-zone-shifting travels. These time zone changes may cause circadian rhythm (CR) phase shifts and these shifts affect sportive performance. The aim of this study was to investigate the effects of CR phase shifts on the performance of NBA teams. 25016 regular season games across 21 consecutive seasons were included in the CR phase shift calculations. To examine the CR phase shift effect on team performance, teams were divided into three groups regarding Coordinated Universal Time (UTC): the same internal UTC as the local UTC (LS); the internal UTC ahead of the local UTC (LA); and the internal UTC behind the local UTC (LB). With a different approach, teams were divided into another three categories: the same internal UTC as its opponent’s internal UTC (OS); the internal UTC ahead of its opponent’s internal UTC (OA); and the internal UTC behind its opponent’s internal UTC (OB). 24985 game data were used to compare these groups in terms of 25 variables. Statistical analyses were conducted separately for home and away teams. For home games, it was found that LA and OA are the most and LB is the least successful group in winning and scoring performances. For away games, it was determined that LS is the most advantageous group with the best winning percentage. These results revealed that teams from more west may have a CR advantage in regular season home games. However, it is thought that the performance of away teams depends more on travel fatigue than CR phase shifts.

Influence of coaxial cable resistance on impedance measurements at low frequency and guidelines for phase determination of ac electrical signals.

We present an experimental study on ac measurements at low frequencies (below 1MHz) when the coaxial cables used for the measurement are resistive, as in cryogenic conditions. More precisely, we are interested in admittance or impedance measurements and the accurate determination of the phase. Our experiments were completed using an auto-balancing bridge impedance analyzer and various standard coaxial cables, as well as their serial combinations. We characterize the experimental setup, and then, we analyze and measure the phase shift introduced in impedance measurements by lead resistance. Using basic equations for electrical signal propagation in coaxial cables, we calculate phase shift in the whole frequency range and explain our data in the low frequency limit of our model. We propose a quantitative criterion to determine whether the experimental context is appropriate. If not, we show that by using an original calibration procedure, the imaginary part can be accurately recovered, avoiding artifacts. The calibration procedure can be applied to any ac voltage or current measurement, whatever the detection technique is, with known accuracy.

An Evaluation of the Signal to Noise Ratio (SNR) of Next Generation Wireless Communication Systems using Large Intelligent Surfaces: Deep Learning Approach

The existing data rate must be greatly increased in order to support the numerous applications of the next generation communication systems. Using Large Intelligent Surfaces (LIS), which are a panel with mounted reflective components, is one way to address this problem. Their primary function is to divert the electromagnetic signal to the intended user. As a result, the received signal's strength and reception quality both improve, improving the Quality of Service (QoS). Machine Learning algorithms have been used to implement LIS in a number of ways, including channel estimation and the calculation of phase shifts (discrete), to mention a few. Here, it is suggested that the Signal to Noise Ratio (SNR) for a LIS-supported communication system be assessed using a Deep Learning (DL) model. On the DL model, the effects of the SGD, Adam RMSProp Adadelta and Adamax optimizers are investigated. The Mean Squared Error (MSE) loss function is taken into account. The Adam optimizer offers the highest level of precision, making it preferable to other optimizers. The SNR for 10 users is measured using the suggested DL model with Adam Optimizer. The outcomes of this work is contrasted with the SNR estimate by an existing technique that calculates SNR based on LIS size and the location of transmitter and receiver with an accuracy of 93.5%. The simulation results indicate that the accuracy is increased to 96% using the suggested DL model which attains an average error of 3.6.

Uncertainties in the transport properties of helium gas at cryogenic temperatures determined using molecular dynamics simulation

In this study, the transport properties, such as diffusivity, viscosity, and thermal conductivity, of 4He at the gaseous phase are computed for state points in the temperature range of 10 K to 150 K and pressure range of 0.10 MPa (1 atm) to 0.21 MPa using classical and quantum frameworks. Within the classical molecular dynamics simulation (MDS), the Green–Kubo (GK) approach is used. The GK method has an inherent uncertainty associated with it due to the random fluctuations in the flux autocorrelation functions. Moreover, in the temperature range of 10 K to 40 K, the quantum nature of the helium gas particles becomes prominent. The classical MDS performed does not include these effects and hence introduces uncertainties in the calculated results. We discuss efficient ways of time averaging the autocorrelation function to reduce statistical fluctuations and perform the quantum scattering phase shift calculations within the Chapman–Cowling theory to study the quantum effects. Furthermore, this study also provides the transport properties data in the cryogenic temperature limit of 10 K to 150 K, which is scarcely studied in the literature and can be applied in complex systems.

The method of calculating the design parameters of a collinear serial antenna using the dispersion characteristics of the retarding system

The paper presents a technique for analyzing the electrical characteristics of series-type collinear antennas made according to the Franklin scheme, which are intended for use in radio communication systems with moving objects as basic or subscriber antenna-feeder devices. Collinear antennas belong to omnidirectional type antennas and allow to significantly increase the amplification factor in comparison with already existing types of antennas of a similar type, which is what attracts antenna technology developers today. The main element of a series-type collinear antenna is a phase-shifting device that determines both the performance of the antenna and its electrical characteristics. The most widely used phase-shifting devices were inductive chokes – a section of conductor of a certain length rolled into a spiral. The proposed engineering method of calculating the parameters of the inductive choke allows you to quickly and accurately adjust its characteristics with the calculation of the necessary phase shift. This approach takes into account the physical parameters of the conductor material and the geometry of the spiral conductor, which greatly simplifies the engineering process of developing collinear antennas. The obtained results of simulation of electrical characteristics confirm the effectiveness of the proposed method. A significant increase in the amplification factor compared to the existing types of antennas and compliance of the electrical characteristics with the specified parameters was revealed. The work has an important contribution to the development of antenna technology and has practical application in radio communication systems with moving objects. The proposed method of calculating the parameters of the inductive choke can be used by antenna developers to increase the productivity and efficiency of their radio communication system.

Incorporating the Coulomb potential into a finite, unitary perturbation theory

We have constructed a perturbation theory to treat interactions that can include the Coulomb interaction, describing a physical problem that is often encountered in nuclear physics. The Coulomb part is not treated perturbatively; the exact solutions are employed. The method is an extension of the results presented in the work of Hoffmann [J. Math. Phys. 62, 032105 (2021)]. It is designed to calculate phase shifts directly rather than the full form of the wavefunctions in position space. We present formulas that allow for the calculation of the phase shifts to second order in the perturbation. The phase shift results to second order, for a short-range potential, were compared with the exact solution, where we found an error of third order in the coupling strength. A different model, meant as a simple approximation of nuclear scattering of a proton on helium-4 and including a Coulomb potential and a spherical well, was constructed to test the theory. The wavepacket scattering formalism of Hoffmann [J. Phys. B: At., Mol. Opt. Phys. 50, 215302 (2017)], known to give everywhere finite results, was employed. We found physically acceptable results and a cross section of the correct order of magnitude.

Importance of atomic physics in verification of experimental results and diagnostics of solar and astrophysical observations

Accurate results are needed to confirm the experimental results of various atomic processes and analyze the solar and astrophysical observations of intensities of emission lines to infer plasma parameters like electron density, electron temperature and element abundance. A number of theories have been developed over the years to calculate phase shifts when electrons and positrons are scattered from targets. We discuss in this article the recent hybrid theory which has been applied to scattering processes, resonances and photoabsorption process, which is a bound-free transition.

Research on Harmonic Generation Mechanism of PSM High-Voltage Power Supply in Dynamic Operation

To study the harmonic generation mechanism of high-voltage power supply (HVPS) in dynamic operation, the mathematical model of the PSM HVPS is built. The mathematical model of the equivalent circuit is established by analyzing the basic operational unit of the HVPS. The initial parameters of the mathematical model are updated according to the number of the modules in series on the load side, and the key electrical parameters set in the mathematical model are obtained. After that, according to the number and the position of the series modules in the HVPS, the current superposition and phase shift calculation are carried out to obtain the harmonic current content in the power grid. This article also verified the accuracy of the mathematical model and calculating method by building a module simulation and HVPS simulation model. Furthermore, the harmonic generation characteristics in the dynamic operation of the HVPS are studied in this article.

Algorithm based on the 1-norm character of interferograms for quantitative differential interference imaging

Differential interference contrast (DIC) microscopy is widely used as a high-contrast imaging method for observing transparent biological samples. However, the absence of fringes in DIC images results in phase gradients that cannot be effectively extracted by most phase-shift algorithms, limiting its application in quantitative detection. Therefore, we propose an algorithm based on the 1-norm character of interferograms that can accurately extract phase shifts from a series of interferograms with less than 1/2 fringes. We improved this algorithm by combining the calculated phase shift with the least-squares fitting method to further extract the phase and applied it to quantitative DIC imaging. In contrast to the conventional algorithm, this algorithm can extract the phase gradient in DIC images with unknown phase shifts, thereby eliminating the computational error in the conventional algorithm introduced by imprecise phase shifts. Simulations and experiments demonstrated that the proposed algorithm can perform accurate phase gradient extraction.

ECCPA: Calculation of classical and quantum cross sections for elastic collisions of charged particles with atoms

ECCPA: Calculation of classical and quantum cross sections for elastic collisions of charged particles with atoms

Dosimetric Evaluation of CyberKnife Synchrony System for Liver Tumors With Respiratory Phase Shifts.

This study evaluated the effects of the respiratory phase shifts between liver tumor and chest wall motions on the dose distribution for the CyberKnife Synchrony respiratory tracking system (SRTS). Eight patients who received stereotactic body radiotherapy for hepatocellular carcinoma or liver metastases were analyzed. Three-dimensional (3D) motion of the implanted fiducial markers and vertical motion of the sternal bone were derived from the four-dimensional computed tomography (4D-CT) images acquired with a 320-row area detector CT. For each patient, Gaussian random numbers were generated for the standard deviation of the tracking error calculated from the phase shift and a literature. For each voxel of the target, the dose delivered from each beam was calculated 100 times with the random 3D offsets representing the tracking error. The median respiratory phase shifts were 6.0% and 4.6% for the anterior-posterior (AP) and superior-inferior (SI) directions, respectively. The median motion tracking errors influenced by respiratory phase shifts were 1.21 mm and 0.96 mm for the AP and SI directions, respectively. The change in the dose covering 90% of the target (D90%) was within 1.1% when median phase shifts were considered. When evaluating the 90th percentile of the phase shifts, the D90% decreased up to 6.6%. We have developed a technique to estimate the impact of the respiratory phase shifts on the dose distribution of a liver tumor treated with the SRTS. The calculation of the respiratory phase shifts from the area-detector 4D-CT will be valuable to improve the tracking accuracy of the SRTS.

The \u03b3\u03c0 \u2192 \u03c0\u03c0 anomaly from lattice QCD and dispersion relations

We propose a formalism to extract the γπ → ππ chiral anomaly F3π from calculations in lattice QCD performed at larger-than-physical pion masses. To this end, we start from a dispersive representation of the γ(*)π → ππ amplitude, whose main quark-mass dependence arises from the ππ scattering phase shift and can be derived from chiral perturbation theory via the inverse-amplitude method. With parameters constrained by lattice calculations of the P-wave phase shift, we use this combination of dispersion relations and effective field theory to extrapolate two recent γ(*)π → ππ calculations in lattice QCD to the physical point. Our formalism allows us to extract the radiative coupling of the ρ(770) meson and, for the first time, the chiral anomaly F3π = 38(16)(11) GeV−3. The result is consistent with the chiral prediction albeit within large uncertainties, which will improve in accordance with progress in future lattice-QCD computations.

Circadian Rhythm: Phase Response Curve and Light Entrainment.

The circadian clock responds to light signals and therefore participates in the plant's daily response to light. The phase response curve (PRC) is typically used in the study of chronobiology to detect the effect of various environmental cues on a given circadian rhythm. In this chapter we describe protocols on measuring the setting of the light pulses at different times of a day, the measurement of circadian rhythm, and the calculation of phase shift in response to light pulses. The promoter:luciferase reporter was used to provide fine rhythmic traces and the subsequent circadian parameters of mathematical analysis. A classical PRC assay to light pulses is the key experimental basis for determining the signal components of resetting the circadian clock.

Real-time quantum calculations of phase shifts using wave packet time delays

We present a method to extract the phase shift of a scattering process using the real-time evolution in the early and intermediate stages of the collision in order to estimate the time delay of a wave packet. This procedure is convenient when using noisy quantum computers for which the asymptotic out-state behavior is unreachable. We demonstrate that the challenging Fourier transforms involved in the state preparation and measurements can be implemented in $1+1$ dimensions with current trapped ion devices and IBM quantum computers. We compare quantum computation of the time delays obtained in the one-particle quantum mechanics limit and the scalable quantum field theory formulation with accurate numerical results. We discuss the finite volume effects in the Wigner formula connecting time delays to phase shifts. The results reported involve two- and four-qubit calculations, and we discuss the possibility of larger scale computations in the near future.

Neutron-Proton Scattering Phase Shifts in S-Channel using Phase Function Method for Various Two Term Potentials

The scattering phase shifts for n-p scattering have been modeled using various two term exponential type potentials such as Malfliet-Tjon, Manning-Rosen and Morse to study the phase shifts in the S-channels. As a first step, the model arameters for each of the potentials are determined by obtaining binding energy of the deuteron using matrix methods vis-a-vis Variational Monte-Carlo (VMC) technique to minimize the percentage error w.r.t. the experimental value. Then, the first order ODE as given by phase function method (PFM), is numerically solved using 5th order Runge-Kutta (RK-5) technique, by substituting the obtained potentials for calculating phase shifts for the bound 3S1 channel. Finally, the potential parameters are varied in least squares sense using VMC technique to obtain the scattering phase-shifts for each of the potentials in the 1S0 channel. The numerically obtained values are seen to be matching with those obtained using other analytical techniques and a comparative analysis with the experimental values up to 300 MeV is presented.

Relativistic Corrections to Phase Shift Calculation in the GNXAS Package

Modern XAFS (X-ray Absorption Fine Structure) data-analysis is based on accurate multiple-scattering (MS) calculations of the X-ray absorption cross-section. In this paper, we present the inclusion and test of relativistic corrections for the multiple-scattering calculations within the GnXAS suite of programs, which is relevant to the treatment of the XAFS signals when atoms with high atomic number are contained into the system. We present a suitable strategy for introducing relativistic corrections without altering the basic structure of the programs. In particular, this is realized by modifying only the Phagen program calculating the atomic absorption cross sections and scattering t-matrices for the selected cluster. The modification incorporates a pseudo-Schrödinger Equation (SE) replacing the Dirac relativistic form. The phase-shift calculations have been put to a test in two known molecular and crystalline cases: molecular bromine Br2 and crystalline Pb. Calculations in an extended energy range have been shown to be very close to the non-relativistic case for Br2 (Br K-edge) while corrections have been found to exceed 25% for amplitude and phases of the XAFS multiple-scattering signals (Pb L3-edge). Benefits in the structural refinement using relativistic corrections are discussed for crystalline Pb at room temperature.

Quantitative imaging for optical field via a single-pixel detector

Quantitative phase imaging (QPI) is important in many applications such as microscopy and crystallography. To quantitatively reveal phase information, people could either employ interferometric pictures for phase shift calculation, or utilize diffraction patterns for phase retrieval reconstruction. Traditionally, both of these two ways use pixelated detectors. In this work, a novel QPI scheme is designed inspired by single-pixel camera (SPC), which retrieves images using structured illumination and single-pixel signals. We use partial coherent light with phase modulation for illumination, and a point detector to detect the zero-order diffraction spectrum of the object. Based on the illumination structures and point signals, a complex value image is reconstructed using a truncated amplitude flow phase retrieval algorithm. This approach is universal for various wavelengths, and needs no a priori information of the targets. Both simulation and experiment show that our single-pixel QPI scheme exhibits great performance even with objects in an extremely rough phase distribution.

Fluid–Structure Interaction Simulation of a Coriolis Mass Flowmeter Using a Lattice Boltzmann Method

In this paper, we use a fluid–structure interaction (FSI) approach to simulate a Coriolis mass flowmeter (CMF). The fluid dynamics is calculated by the open-source framework OpenLB, based on the lattice Boltzmann method (LBM). For the structural dynamics we employ the open-source software Elmer, an implementation of the finite element method (FEM). A staggered coupling approach between the two software packages is presented. The finite element mesh is created by the mesh generator Gmsh to ensure a complete open source workflow. The Eigenmodes of the CMF, which are calculated by modal analysis, are compared with measurement data. Using the estimated excitation frequency, a fully coupled, partitioned, FSI simulation is applied to simulate the phase shift of the investigated CMF design. The calculated phase shift values are in good agreement to the measurement data and verify the suitability of the model to numerically describe the working principle of a CMF.