Phase-shift Analysis Research Articles

Quantitative Flow Visualization of Slightly Underexpanded Microjets by Mach\u2013Zehnder Interferometers

The Mach–Zehnder interferometer with the finite fringe setting is applied for a shock-containing microjet issued from an axisymmetric convergent nozzle with an inner diameter of 1.0 mm at the exit. Experiments are performed at a nozzle pressure ratio of 3.0 to produce a slightly underexpanded sonic jet where the Reynolds number, based upon the diameter and flow properties at the nozzle exit, is 4.45 times 10^4. The reconstruction of the jet density field is performed using the Abel inversion method under the assumption of an axisymmetric flow as well as the Fourier transform method for the phase shift analyses of interferograms. The three-dimensional density field of a shock-containing microjet can be captured with a spatial resolution of 4 upmum, and the near-field shock structure inside the jet plume is shown in the density contour plot at the cross-section including the jet centerline. In addition, the density field of the microjet is illustrated with various techniques, including representation such as the vertical-knife-edge schlieren, the horizontal-knife-edge schlieren, the bright-field schlieren, and the shadowgraphy. In addition to experiments, the Reynolds averaged Navier–Stokes (RANS) simulation with the SST k–omega turbulence model is carried out to model the microjets, and a quantitative comparison with the experiments is performed. The jet centerline density profile obtained by the present experiment is quantitatively compared with those from the previous Mach–Zehnder interferometer, the background oriented schlieren, as well as the RANS simulation.

A Simple Approach for Determination of Numerical Values of Ferrite Nonlinear Susceptibilities

This article presents a straightforward approach for determination of numerical values of nonlinear susceptibilities of soft magnetic ferrites. It is shown that numerical values of susceptibilities can be calculated from the measured amplitudes of harmonics in the output voltage of ferrite core transformer. For this purpose, useful expressions for the susceptibilities are derived and as example, numerical values of the largest nonlinear susceptibilities those of the third and fifth orders are calculated. Additionally, errors of the measured susceptibilities also are determined. Based on the expressions obtained, the analysis of phase shifts between components of flux density on different frequencies and the magnetic field strength also is performed. The comparison of the calculated and measured output voltage waveforms allows concluding that in the frequency range where losses are small and can be neglected, the susceptibility of the third order is negative but that of the fifth order is positive.

Elastic scattering of electrons and positrons from 115In atoms over the energy range 1 eV–0.5 GeV

We present a theoretical study on the calculations of various cross sections related to the scattering of electrons and positrons from indium atoms. Our calculations cover the energy range 1 eV ⩽Ei⩽0.5 GeV. We have employed two approaches, applicable for two domains of energy, based on the Dirac partial-wave analysis. In one approach, we have used both the atomic and nuclear potentials to calculate the cross sections for the low and intermediate energies. The other approach, valid for the high-energy scattering, utilizes only the nuclear potential for the phase-shift analysis, and considers the magnetic scattering from the nucleus too. We report the calculations of differential, integral, momentum-transfer and viscosity cross sections along with the spin asymmetries for the elastic scattering of electrons and positrons. Moreover, we have analyzed the critical minima in the elastic differential cross sections, and also computed the absorption and total cross sections. Our results agree reasonably with the available experimental data and other calculations.

Thickness profiling of transparent plate using wavelength-tuned phase-shifting analysis

Abstract In the interferometric phase-shifting analysis, the phase-shift nonlinearity causes both uniform and non-uniform phase errors in the phase distribution. In this research, a novel 13-frame phase-extraction algorithm that can suppress the uniform phase error was derived. The characteristics of the new 13-frame algorithm are discussed using a Fourier description. Additionally, the error suppression ability of the new 13-frame algorithm was performed by numerical error analysis, with comparisons to de Groot 13, Hibino 19, Hanayama 11, and 17-frame algorithms. Numerical analysis indicates that the new 13-frame algorithm shows the best performance (under 2 nm when 30% linear miscalibration and under 0.5 nm when the nonlinearity 10%). Finally, the variation in thickness of a transparent plate was profiled by the new 13-frame algorithm and a Fizeau interferometer. The repeatability standard deviation of experiments using the 13-fram algorithm was 3.344 nm, which shows the better performance that those of other conventional algorithms.

Effect of morphed trailing-edge flap on aerodynamic load control for a wind turbine blade section

Application of Morphed Trailing-Edge Flap (MTEF) can significantly reduce the excessive loads that cause damage of blades and surrounding components in wind turbine. The present paper investigates the effect of MTEF on the aerodynamic load control of a large-scale wind turbine blade. Three design parameters that control MTEF kinematics, such as deflection length, amplitude and phase shift, are analyzed in detail by a validated Computational Fluid Dynamic (CFD) model, in which a specially-designed mesh update method is adopted. Results show that, compared with fully rigid airfoil, the morphed airfoil exhibits an excellent load control capability owing to the appropriate change of aft effective camber as deflection motion of MTEF, which significantly alters the pressure distribution and air flow. Furthermore, the performances are linearly improved with increasing MTEF deflection length, wherein every 0.1c increase in length results in the percentage variation of CL, min (+45%), CL, max (−3%), CD, max (−5%) and CL/CD (+30%). Whereas the improved performance due to the increase of deflection amplitude shows a reducing trend, and an oversize deflection amplitude (greater than βamp = 10°) leads to the depravation of aerodynamic efficiency. Moreover, the analysis of deflection phase shift suggests that a slight phase–lag is beneficial to stabilize the aerodynamic load exerted on wind turbine blade. Especially, the lift coefficient fluctuation (CL, max−CL, min) for the phase-lag case of φ = 1/8π has reduced by about 50% while the cycle-averaged lift coefficient has increased by 16.67% as compared to the fully rigid airfoil. The results of this paper will help guide future development and application of MTEF in practice.

Analytical Expressions for the Differential Elastic Scattering Cross Sections of Nonidentical Nuclear Particles with Channel Spin 1 and 2

In this paper, general analytical expressions are obtained for the differential elastic scattering cross sections of two nuclear particles with allowance for spin-orbit splitting for channels with the half-integer spins 3/2 and 5/2, which are parameterized with respect to the orbital quantum number l. This representation makes it possible to take into account explicitly a definite, energy-dependent number of scattering partial waves and to consider the relative contribution of each partial wave. The obtained expressions can be used when performing phase shift analysis in elastic scattering of nonidentical particles, for example, N2H, N6Li, 2H7Li, and 2H9Be at low energies.

Application of relativistic coupled cluster theory to elastic scattering of electrons from confined Ca atoms

We have developed relativistic coupled-cluster (RCC) theory to study elastic scattering of electrons from free and confined Ca atoms. For this purpose, we first investigated electron correlation effects on the atomic properties of the Ca atom trapped inside an attractive spherically symmetric potential well of an endohedral fullerene C60 cluster and obtained electron correlation energy, ionization potential and dipole polarizability of this atom. Our results are compared with the reported calculations employing multi-configuration Hartree–Fock (MCHF) method. We found that trends in correlation energy with respect to the potential depth are the same, but magnitudes are very large in the relativistic calculations. Finally, using the obtained charge density and phase shift analysis technique we determined the differential and total cross-sections for elastic scattering of electrons from free and confined Ca atoms and demonstrated the role of potential depth in these properties.

Integer and half-integer channel spins for elastic scattering cross sections

We present analytical expressions for differential cross sections and independent partial amplitudes of elastic scattering of nuclear particles for channels with a spin value of 1/2, 1, 3/2, 2 and 5/2. The independent partial amplitudes are calculated taking into account the spin-orbit splitting for arbitrary orbital angular momentum l. The analytical expressions allow one to carry out full phase shift analysis using experimental data of differential cross sections for processes with channel spins 1/2, 1, 3/2, 2 and 5/2.

Compensation for the Influence of Fluctuations in the Distance to the Object During Noncontact Probing in Spectral Domain Optical Coherence Tomography

We propose and experimentally test a numerical method for correction of the influence of fluctuations in the distance to objects during noncontact probing in optical coherence tomography. The method is based on the analysis of phase shifts of the neighboring scans, which are due to microscale displacements, and further compensation for these displacements by using phasefrequency correction in the spectral domain. Unlike the known correlation methods, the proposed method does not distort the represented shape of the object surface. Its operability is demonstrated in model experiments in the cases of harmonic and random types of the motion of the scattering object, as well as in vivo imaging of the structures of the human middle ear.

Complex interactions between day length and diurnal patterns of gene expression drive photoperiodic responses in a perennial C4 grass.

Photoperiod is a key environmental cue affecting flowering and biomass traits in plants. Key components of the photoperiodic flowering pathway have been identified in many species, but surprisingly few studies have globally examined the diurnal rhythm of gene expression with changes in day length. Using a cost-effective 3'-Tag RNA sequencing strategy, we characterize 9,010 photoperiod responsive genes with strict statistical testing across a diurnal time series in the C4 perennial grass, Panicum hallii. We show that the vast majority of photoperiod responses are driven by complex interactions between day length and sampling periods. A fine-scale contrast analysis at each sampling time revealed a detailed picture of the temporal reprogramming of cis-regulatory elements and biological processes under short- and long-day conditions. Phase shift analysis reveals quantitative variation among genes with photoperiod-dependent diurnal patterns. In addition, we identify three photoperiod enriched transcription factor families with key genes involved in photoperiod flowering regulatory networks. Finally, coexpression networks analysis of GIGANTEA homolog predicted 1,668 potential coincidence partners, including five well-known GI-interacting proteins. Our results not only provide a resource for understanding the mechanisms of photoperiod regulation in perennial grasses but also lay a foundation to increase biomass yield in biofuel crops.

Investigation on Producing the Flux Cored Wire Modified with Concentrated Complex from Tomtor Mineral Assets

Multiple use of pan concentrate from placer deposits directly in technical process without prealltoment of pure components could become one of promising directions in the field of receiving wide range of multicomponent metal and ceramic powdered materials. In this paper as the object of comparative examination, we present the hemimethylated plating made of exploited experimentative flux cored wires based on industrial Ni-Cr-B-Si system powder modified with rare-earth elements of concentrated complex from Tomtor mineral assets Republic of Sakha (Yakutia). The structure of received plating is heterogeneous and has oxidation coating as boundaries. According to the data of the phase shift analysis plating predominantly consist of Fe-Ni austenitic alloy phases with the Cr, Si carbide and Cr boride precipitation strengthening, plating generally consist of Al2O3, Cr2O3 и Fe2O3 oxide. The research of the plating ultimate composition testifies the equable allocation of main and alloying elements, local location of some elements in the structure of the plating. Microhardness of flux cored wire plating substantially depends on composition and fabricated structure. It has been established that the introduction of rare earth elements provided the formation of strengthening phase with the high hardness of plating resulting in wear resistance increase.

Supernumerary bows: caustics of a refractive sphere and analysis of the relative overall Gouy phase shift of supernumerary rays.

The modified Young's theory of interference related to supernumerary rainbows is based on a difference of 90° in the Gouy phase shifts for the parallel rays producing these bows. An observation screen placed at a given distance from a refractive sphere illuminated by a point source of light should also show supernumerary screen bows. An extensive description and analysis of the caustics involved are given. For any k order, k being the number of reflections inside the sphere, a procedure is established to determine the number of Gouy phase shifts encountered by any ray along its path from the source to the screen. Special consideration is given to the order k=0. For any k supernumerary bow, on any spherical screen whose center is that of the sphere, the difference in the Gouy phase shifts for the two rays producing a bow always amounts to 90°. An indirect proof of this characteristic is given. All considerations are made within the framework of geometrical optics being, on the one hand, the limit of the electromagnetic theory as the wavelength goes to 0, and being, on the other hand, complemented by the Gouy phase shift theory.

Combining multiple structural inversions to constrain the solar modelling problem

Context. The Sun is the most studied of all stars, which serves as a reference for all other observed stars in the Universe. Furthermore, it also serves the role of a privileged laboratory of fundamental physics and can help us better understand processes occuring in conditions irreproducible on Earth. However, our understanding of our star is currently lessened by the so-called solar modelling problem, resulting from comparisons of theoretical solar models to helioseismic constraints. These discrepancies can stem from various causes, such as the radiative opacities, the equation of state as well as the mixing of the chemical elements. Aims. By analysing the potential of combining information from multiple seismic inversions, our aim is to help disentangle the origins of the solar modelling problem. Methods. We combined inversions of the adiabatic sound speed, an entropy proxy and the Ledoux discriminant with other constraints such as the position of the base of the convective zone and the photospheric helium abundance. First, we tested various combinations of standard ingredients available for solar modelling such as abundance tables, equation of state, formalism for convection and diffusion and opacity tables. Second, we studied the diagnostic potential of the inversions on models including ad hoc modifications of the opacity profile and additional mixing below the convective envelope. Results. We show that combining inversions provides stringent constraints on the required modifications to the solar ingredients, far beyond what can be achieved from sound speed inversions alone. We constrain the form and amplitude of the opacity increase required in solar models and show that a 15% increase at log T = 6.35 provides a significant improvement, but is insufficient on its own. A more global increase in the opacity, within the uncertainties of the current tables, coupled with a localized additional mixing at the bottom of the convective zone provides the best agreement for low-metallicity models. We show that high-metallicity models do not satisfy all the inversion results. We conclude that the solar modelling problem likely occurs from multiple small contributors, as other ingredients such as the equation of state or the formalism of convection can induce small but significant changes in the models and that using phase shift analyses combined with our approach is the next step for a better understanding of the inaccuracies of solar models just below the convective envelope.

Phase Shift Analysis of $^{6}$Li Elastic Scattering on $^{12}$C and $^{28}$Si at $E_{lab}$ = 318 MeV

We present a three-parameter phase shift model whose form is the same as that of Coulomb-modified Glauber model obtained from Gaussian nuclear densities. This model is applied to the $^{6}$Li + $^{12}$C and the $^{6}$Li + $^{28}$Si elastic scatterings at $E_{lab}$ = 318 MeV. The calculated differential cross sections provide quite a satisfactory account of the experimental data. The diffractive oscillatory structures observed at forward angles can be explained as being due to the strong interference between the near-side and the far-side scattering amplitudes. The optical potentials for two systems are predicted by using the method of inversion. The calculated inversion potentials are found to be in fairly good agreements with the results determined from the optical model analysis in the surface regions around the strong absorption radius. We also investigate the effects of parameters in the three-parameter phase shift model on the elastic scattering cross sections.

Comparative study of eV to GeV electrons and positrons scattering elastically from neutral atoms

Differential cross sections and spin asymmetries for leptons colliding with light and heavy targets are calculated at collision energies Ee ranging from 1 eV to 0.3 GeV. For , the partial-wave phase shift analysis for solving the relativistic Dirac equation is used within an optical model potential, and for within the nuclear potential. At , the phase shift analysis is supplemented with the distorted-wave Born approximation to account for magnetic scattering. As test cases, elastic collisions of e± with 23Na, 112Cd and 208Pb atoms are reported, and good agreement with available experimental data and other theoretical cross sections is obtained. For electrons, pronounced structures in the spin asymmetry occur at low energies and small scattering angles. They disappear beyond 50 keV and reappear beyond 50 MeV, being then particularly strong for spin-zero nuclei at large scattering angles. For positrons, the high-energy diffraction structures are shifted in phase with respect to those in the electron spin asymmetry. The strong reduction of the positron spin asymmetry and the quenching of the structures at low-energy is interpreted in terms of a dominating action of the nuclear potential.

Real time recognition of explosophorous group and explosive material using laser induced photoacoustic spectroscopy associated with novel algorithm for time and frequency domain analysis

Energy-rich bonds such as nitrates (NO3−) and percholorates (ClO4−) have an explosive nature; they are frequently encountered in high energy materials. These bonds encompass two highly electronegative atoms competing for electrons. Common explosive materials including urea nitrate, ammonium nitrate, and ammonium percholorates were subjected to photoacoustic spectroscopy. The captured signal was processed using novel digital algorithm designed for time and frequency domain analysis. Frequency domain analysis offered not only characteristic frequencies for NO3− and ClO4− groups; but also characteristic fingerprint spectra (based on thermal, acoustical, and optical properties) for different materials. The main outcome of this study is that phase-shift domain analysis offered an outstanding signature for each explosive material, with novel discrimination between explosive and similar non-explosive material. Photoacoustic spectroscopy offered different characteristic signatures that can be employed for real time detection with stand-off capabilities. There is no two materials could have the same optical, thermal, and acoustical properties.

Improving the measurement accuracy of shadow moiré by three-step random phase-shifting algorithm

Phase-shifting shadow moire is an efficient technique for three-dimensional (3-D) shape measurement, but the technique is always suffered from the error of phase shifter. A three-frame random phase-shifting algorithm is proposed to relax the requirements of repeatability and accuracy of the phase shifter in a shadow moire system. The proposed method can act as a bridge between the three phase-shifting analysis methods and two-shot phase-shifting methods. The value of introduced arbitrary and unknown phase shift can be calculated by a determinate formula. The algorithm has the advantages of being free from the disturbance of background elimination and less computation. In addition, the proposed method is immune to nonsinusoidal fringe patterns and can be implemented easily in many applications. Both simulation and optical experimental results verify the feasibility of this method.

Phase-shift Fault Analysis of Grain v1

This paper deals with the phase-shift fault analysis of stream cipher Grain v1. We assume that the attacker is able to desynchronize the linear and nonlinear registers of the cipher during the keystream generation phase by either forcing one of the registers to clock one more time, while the other register is not clocked, or by preventing one of the registers from clocking, while the other register is clocked. Using this technique, we are able to obtain the full inner state of the cipher in reasonable time (under 12 hours on a single PC) by using 150 bits of unfaulted keystream, 600 bits of faulted keystreams and by correctly guessing 28 bits of the linear register.

Microstructural and Functional Imaging of the Intact Sinoatrial Node Detects Heterogenous Ca2+-Driven Intra and Intercellular Communications that Lead to Pacing Perfection

Cells within the sinoatrial node (SAN), the primary pacemaker of the heart, are extremely heterogeneous in size, morphology and electrophysiological characteristics. A coupled-clock theory suggests that rhythmic action potential (AP) firing is generated by tight interactions of rhythmic local Ca releases with cell surface membrane ion channels and transporters. This mechanism was reported in single cells, but has not been systematically explored within cells residing in intact SAN tissue. We developed novel Ca imaging techniques to visualize the spread of the impulse across the entire network of SAN cells and local Ca release dynamics within individual cells. Immunolabeling of Connexin-43 and HCN4 was employed to correlate cytoarchitecture with Ca activity. Rhythmic AP-induced Ca transients (APCTs), which correlated with APs recorded simultaneously using sharp microelectrode, were employed to monitor the impulse conduction across the SAN. The site at which the earliest APCTs occurred, identified by phase shift analysis, was between crista terminalis and superior vena cava. The APCT travels from this area across the entire SAN along curvilinear bundles of striated SAN cells rich in Connexion-43 and weak in HCN4 immunolabeling. LCRs were observed in all areas of SAN, including cells within the conduction bundles. Cells close to the APCT initiation site generated only rhythmic LCRs (without APCTs) and these LCRs preceded APCTs in the cells of the APCT-initiation area. Cells close to APCT initiation site were rich in HCN4, but essentially devoid of Connexin-43 and striations. Our results are consistent with the hypothesis that a coupled-clock system operates both within and among cells comprising the SAN network: some specialized cells generate only rhythmic LCRs that ignite adjacent cells to initiate the impulse that propagates throughout the SAN cell network.

Phase Shift Analysis and the Optical Potential Obtained by Using Inversion for $alpha$ + $^{58}$Ni Elastic Scattering

Phase Shift Analysis and the Optical Potential Obtained by Using Inversion for $alpha$ + $^{58}$Ni Elastic Scattering