Real-time ultrafast oscilloscope with a relativistic electron bunch train

The deflection of charged particles is an intuitive way to visualize an electromagnetic oscillation of coherent light. Here, we present a real-time ultrafast oscilloscope for time-frozen visualization of a terahertz (THz) optical wave by probing light-driven motion of relativistic electrons. We found the unique condition of subwavelength metal slit waveguide for preserving the distortion-free optical waveform during its propagation. Momentary stamping of the wave, transversely travelling inside a metal slit, on an ultrashort wide electron bunch enables the single-shot recording of an ultrafast optical waveform. As a proof-of-concept experiment, we successfully demonstrated to capture the entire field oscillation of a THz pulse with a sampling rate of 75.7 TS/s. Owing to the use of transversely-wide and longitudinally-short electron bunch and transversely travelling wave, the proposed “single-shot oscilloscope” will open up new avenue for developing the real-time petahertz (PHz) metrology.

Decomposing the geomagnetic field: oscillation modes and characteristics

<p>Using the COV-OBS.x1 (Gillet et al., 2015) main geomagnetic field model, covering the time span 1840–2020, respectively IGRF-13 (1900-2020), we decomposed the geomagnetic field at Earth’s surface in oscillation modes by means of empirical orthogonal functions (EOF) as well into a long term and a cyclic component using HP filtering (Hodrick and Prescott, 1997). Further, the long term component is filtered using a Butterworth filter (1930) with different cut-off periods in order to obtain oscillation at inter-centennial (> 100 years) and sub-centennial (60-90 years) timescales. The EOF analysis shows that the first three oscillation modes are characterized by periodicities of >100 years while modes 4 and 5 are characterized by dominant periodicities of 70-90 year. Although the variance of the modes 4 and 5 is rather small compared to that of the first three modes, these two modes are responsible for the detailed structure of the geomagnetic field. A comparison between the results of both methods is done as well.</p>

Simplified P-representation operator correspondence applied to quantum systems with generalized Kerr nonlinearity

A simplified operator correspondence scheme is derived to address nonlinear quantum systems within the framework of the [Formula: see text]-representation. The simplified method is applied to a general nonlinear quantum oscillator model that has been used in the literature to describe nonlinear quantum optical and matter wave systems. The [Formula: see text]-representation evolution equation for the model is derived for arbitrary nonlinearity exponents. It is shown that in the high temperature case, the [Formula: see text]-representation is sufficient to describe the model and its associated systems such that there is no need to use alternative, mathematically more involved representations. Systems with quadratic and cubic nonlinearities are considered in more detail. Distributions for the energy levels and photon and particle numbers are obtained within the framework of the [Formula: see text]-representation. Moreover, the electrical field oscillation frequency dependency is studied numerically when interpreting the model as model for quantum optical nonlinear oscillators.

Generalized Galileon scenario inspires chaotic inflation

We study chaotic inflation with a Galileon-like self-interaction $$G(\phi ,X)\Box \phi $$G(ϕ,X)□ϕ, where $$G(\phi ,X)\propto X^{n}$$G(ϕ,X)∝Xn. General conditions required for successful inflation are deduced and discussed from the background and cosmological perturbations under slow-roll approximation. Interestingly, it is found that in the regime where the Galileon term dominates over the standard kinetic term, the tensor-to-scalar ratio becomes significantly suppressed in comparison to the standard expression in General Relativity (GR). Particularly, we find the allowed range in the space of parameters characterizing the chaotic quadratic and quartic inflation models by considering the current observational data of Planck from the $$n_{\mathcal {S}}-r$$nS-r plane. Finally, we discuss about the issue if the Galileon term is dominant by the end of inflation, this can affect the field oscillation during reheating.

Survey of Demosaicking Methods for Polarization Filter Array Images

Snapshot polarization imaging has gained interest in the last few decades. Recent research and technology achievements defined the polarization Filter Array (PFA). It is dedicated to division-of-focal plane polarimeters, which permits to analyze the direction of light electric field oscillation. Its filters form a mosaicked pattern, in which each pixel only senses a fraction of the total polarization states, so the other missing polarization states have to be interpolated. As for Color or Spectral Filter Arrays (CFA or SFA), several dedicated demosaicking methods exist in the PFA literature. Such methods are mainly based on spatial correlation disregarding inter-channel correlation. We show that polarization channels are strongly correlated in images. We therefore propose to extend some demosaicking methods from CFA/SFA to PFA, and compare them with those that are PFA-oriented. Objective and subjective analysis show that the pseudo panchromatic image difference method provides the best results and can be used as benchmark for PFA demosaicking.

Interplanetary External Driven Quasidynamo as the Origin of Geomagnetic Jerks Correlated with Length of Day and Gravity Anomaly

We report phenomenological inevitable correlation between the Sun’s magnetic field oscillation through the Earth and the Jupiter, with sinusoidal geomagnetic jerks observed at the Earth, additionally aligned with the gravity and length of day sinusoidal variations and we observe too that the Sun and Jovian planets alignments with Jupiter are origin of the observable abrupt geomagnetic jerks whether historical or new, and experimental results demonstrate a possible explanation on the base of the planetary induced currents upon the metallic liquid cores of the planets upon the varying external magnetic fields as the source of heat flows continued by frictional turbulent and convectional fluid fluxes, amplified and expanding by the Earth magnetic field and observations are showing too that it should be an electric coupling effect between metallic cores of the planets, under the magnetic field oscillation so that Jupiter conductive metallic region interacts with Earth metallic core while the Sun’s magnetic field is oscillating through the Jupiter and we see a relation between secular variation of the Earth’s magnetic field and long term trend of 5.9-years signals as a new method to measure geomagnetic secular variation by LOD signals.

Comparison of Dynamic and Aerodynamic Characteristics of the Centrifugal Fan Calculated by Different Methods

The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteristics based on numerical modeling. Three variants of geometry were investigated. The first, basic “A” variant contains 12 blades. The geometry of second “B” variant contains 12 blades and 12 semi-blades with optimal length [1]. The third, control variant “C” contains 24 blades without semi-blades. Numerical calculations were performed by CFD Ansys and OpenFoam. Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated for to determine characteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also partially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calculation stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using of frequency analysis for the each variant and working condition.