Three‐dimensional relativistic scattering of electromagnetic waves by an object in uniform translational motion

1981 ◽  
Vol 22 (11) ◽  
pp. 2716-2722 ◽  
Author(s):  
B. L. Michielsen ◽  
G. C. Herman ◽  
A. T. de Hoop ◽  
D. de Zutter
Keyword(s):  
Electromagnetic Waves ◽  
Translational Motion ◽  
Three Dimensional ◽  
Relativistic Scattering

Biomechanical characteristics of C1–2 cable fixations

1996 ◽  
Vol 85 (2) ◽  
pp. 316-322 ◽  
Author(s):  
Curtis A. Dickman ◽  
Neil R. Crawford ◽  
Christopher G. Paramore
Keyword(s):  
Cyclic Loading ◽  
Translational Motion ◽  
Biomechanical Testing ◽  
Three Dimensional ◽  
Constrained Motion ◽  
Content Type ◽  
Physiological Range ◽  
Fixation Techniques ◽  
Cable Fixation ◽  
Fine Print

✓ The biomechanical characteristics of four different methods of C1–2 cable fixation were studied to assess the effectiveness of each technique in restoring atlantoaxial stability. Biomechanical testing was performed on the upper cervical spines of four human cadaveric specimens. Physiological range loading was applied to the atlantoaxial specimens and three-dimensional motion was analyzed with stereophotogrammetry. The load–deformation relationships and kinematics were measured, including the stiffness, the angular ranges of motion, the linear ranges of motion, and the axes of rotation. Specimens were nondestructively tested in the intact state, after surgical destabilization, and after each of four different methods of cable fixation. Cable fixation techniques included the interspinous technique, the Brooks technique, and two variants of the Gallie technique. All specimens were tested immediately after fixation and again after the specimen was fatigued with 6000 cycles of physiological range torsional loading. All four cable fixation methods were moderately flexible immediately; the different cable fixations allowed between 5° and 40° of rotational motion and between 0.6 and 7 mm of translational motion to occur at C1–2. The Brooks and interspinous methods controlled C1–2 motion significantly better than both of the Gallie techniques. The motion allowed by one of the Gallie techniques did not differ significantly from the motion of the unfixed destabilized specimens. All cable fixation techniques loosened after cyclic loading and demonstrated significant increases in C1–2 rotational and translational motions. The bone grafts shifted during cyclic loading, which reduced the effectiveness of the fixation. The locations of the axes of rotation, which were unconstrained and mobile in the destabilized specimens, became altered with cable fixation. The C1–2 cables constrained motion by shifting the axes of rotation so that C-1 rotated around the fixed cable and graft site. After the specimen was fatigued, the axes of rotation became more widely dispersed but were usually still localized near the cable and graft site. Adequate healing requires satisfactory control of C1–2 motion. Therefore, some adjunctive fixation is advocated to supplement the control of motion after C1–2 cable fixation (that is, a cervical collar, a halo brace, or rigid internal fixation with transarticular screws).

scholarly journals Quantum Structured Light: Non-classical Spin Texture of Twisted Single-photon Pulses

2021 ◽  
Author(s):  
Li-Ping Yang ◽  
Zubin Jacob
Keyword(s):  
Spin Density ◽  
Electromagnetic Waves ◽  
Single Photon ◽  
Structured Light ◽  
Three Dimensional ◽  
Quantum Spin ◽  
Single Photons ◽  
Spin Order ◽  
Spin Noise ◽  
Spin Texture

Abstract Classical structured light with controlled polarization and orbital angular momentum (OAM) of electromagnetic waves has varied applications in optical trapping, bio-sensing, optical communications and quantum simulations. The classical electromagnetic theory of such structured light beams and pulses have advanced significantly over the last two decades. However, a framework for the quantum density of spin and OAM for single-photons remains elusive. Here, we develop a theoretical framework and put forth the concept of quantum structured light for space-time wavepackets at the single-photon level. Our work marks a paradigm shift beyond scalar-field theory as well as the paraxial approximation and can be utilized to study the quantum properties of the spin and OAM of all classes of twisted quantum light pulses. We capture the uncertainty in full three-dimensional (3D) projections of vector spin demonstrating their quantum behavior beyond the conventional concept of classical polarization. Even in laser beams with high OAM along the propagation direction, we predict the existence of large OAM quantum fluctuations in the transverse plane which can be verified experimentally. We show that the spin density generates modulated helical texture beyond the paraxial limit and exhibits distinct statistics for Fock-state vs. coherent-state twisted pulses. We introduce the quantum correlator of photon spin density to characterize the nonlocal spin noise providing a rigorous parallel with fermionic spin noise operators. Our work paves the way for quantum spin-OAM physics in twisted single photon pulses and also opens explorations for new phases of light with long-range spin order.

Compact Dual-Passband Three-Dimensional FSS with Good Angular Stability and Both-Side Fast Roll-Off Characteristics

2021 ◽  
Vol 36 (6) ◽  
pp. 664-669
Author(s):  
Zhengyong Yu ◽  
Baozhu Li ◽  
Shenggao Ding ◽  
Wanchun Tang
Keyword(s):  
Electromagnetic Waves ◽  
Electromagnetic Coupling ◽  
Three Dimensional ◽  
Frequency Selective Surface ◽  
Resonant Mode ◽  
Unit Cell ◽  
Angular Stability ◽  
Propagation Path ◽  
Annular Slot ◽  
Parallel Plate Waveguide

A compact dual-passband three-dimensional (3D) frequency selective surface (FSS) is proposed based on multiple square coaxial waveguides (SCWs), which exhibits good angular stability and both-side fast roll-off characteristics. The unit cell of the proposed 3D FSS is composed of one parallel plate waveguide (PPW) propagation path and two SCW propagation paths. By etching a centered annular slot, each SCW path forms two identical short SCWs. Each short SCW inherently generates one square slot resonance. In each SCW path, on the account of electromagnetic coupling between two square slot resonators provided by two short SCWs, the square slot resonant mode will split into even-/odd-resonant modes. Accordingly, each SCW path can provide a flat second-order passband with two transmission poles. Due to the reflection and out of phase of electromagnetic waves, four transmission zeros located at both sides of the passbands are introduced for high frequency selectivity, realizing both-side fast roll-off performances. In order to explain the operating principle, the electric-field distributions at transmission-zero/pole frequencies are investigated. Finally, an FSS prototype is fabricated and measured, and the results exhibit good angular stability for both TE and TM polarizations under incident angles from 0° to 60°. In addition, the proposed 3D FSS has a compact unit cell.

scholarly journals The Foshan Total Lightning Location System in China and Its Initial Operation Results

Atmosphere ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 149 ◽  
Author(s):  
Li Cai ◽  
Xin Zou ◽  
Jianguo Wang ◽  
Quanxin Li ◽  
Mi Zhou ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Radar Data ◽  
Time Of Arrival ◽  
Initial Operation ◽  
Lightning Strikes ◽  
Location System ◽  
Lightning Location System ◽  
Total Lightning ◽  
Operation Results

In the summer of 2013, a three-dimensional (3D)-based Foshan Total Lightning Location System (FTLLS), embedded with differential time of arrival (DTOA) techniques, was installed and started its operation in Foshan, Guangdong Province, China. In this paper, the geographical distribution and set-up information of FTLLS, the estimated locating errors and locating results, as well as its initial operation results are presented. FTLLS consists of nine sub-stations that receive electromagnetic waves associated with lightning discharges and locates VLF/LF (200 Hz–500 kHz) radiation sources in 3D. The remote sub-stations acquired triggered waveforms with a duration of 0.5 ms, a resolution of 12-bits, and a GPS-based sferic time tags of 24 h per day. Cloud-to-ground (CG) lightning events, intra-cloud (IC) lightning events and narrow bipolar events (NBEs) were located by FTLLS. Based on the Monte Carlo simulation, the two-dimensional horizontal location error is basically less than 100 m, and the vertical error (altitude) is less than 200 m when the lightning event occurs within the network. On the other hand, over 14 million lightning strikes were recorded successfully by FTLLS during the period of May to October in 2014, among which IC events, CG events and NBEs accounted for 65%, 34% and 1%, respectively. It is shown that FTLLS is capable of a fine three-dimensional (3D) location, in which the altitude parameters obtained are reasonable and well consistent with observed data in the previous studies. The location results of thunderstorms were additionally verified through simultaneously-observed radar data.

scholarly journals Evaluation of the Laguerre–Gaussian mode purity produced by three-dimensional-printed microwave spiral phase plates

2020 ◽  
Vol 7 (7) ◽  
pp. 200493
Author(s):  
D. Isakov ◽  
Y. Wu ◽  
B. Allen ◽  
P. S. Grant ◽  
C. J. Stevens ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Direct Fabrication ◽  
Dielectric Lens ◽  
Gaussian Mode ◽  
Phase Plates ◽  
Mode Purity ◽  
Aided Design ◽  
Spiral Phase

Computer-aided design software and additive manufacturing provide flexibility for the direct fabrication of multi-material devices. This design and fabrication versatility has been investigated for the manufacture of dielectric spiral phase plates (SPP) that generate electromagnetic waves with helical wavefronts. Three types of SPPs designed to produce an orbital angular momentum (OAM) mode number l = |1| were additively manufactured using material extrusion and polyjet fabrication methods. The OAM mode characteristics of the transformed helical microwaves as a function of the SPP geometrical features were investigated experimentally in the 12–18 GHz frequency range. The SPPs were further combined with an additively manufactured dielectric lens that provided a marked improvement in OAM mode purity. Finally, multiplexing and de-multiplexing of two OAM modes were demonstrated successfully using an optimum SPP geometry and arrangement.

scholarly journals Electromagnetic radiation of oscillating thin films

2019 ◽  
Vol 30 ◽  
pp. 06004
Author(s):  
Alexander V. Kharlanov
Keyword(s):  
Thin Films ◽  
Numerical Simulation ◽  
Electromagnetic Radiation ◽  
Electromagnetic Fields ◽  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Cell Group ◽  
Exchange Of Information ◽  
Dimensional Cell

This paper deals with the electromagnetic fields generated by charges moving with the membrane. The numerical simulation of electromagnetic radiation of oscillating three-dimensional cell it is carried out. The issues of cell group radiation are also considered. Dependences of the field on distance and time are presented. A hypothesis about possible exchange of information between cells by means of electromagnetic waves is made.

scholarly journals Topology optimization for three-dimensional electromagnetic waves using an edge element-based finite-element method

2016 ◽  
Vol 472 (2189) ◽  
pp. 20150835 ◽  
Author(s):  
Yongbo Deng ◽  
Jan G. Korvink
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Topology Optimization ◽  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Free Condition ◽  
Edge Element ◽  
Divergence Free ◽  
The Magnetic Field ◽  
Element Method

This paper develops a topology optimization procedure for three-dimensional electromagnetic waves with an edge element-based finite-element method. In contrast to the two-dimensional case, three-dimensional electromagnetic waves must include an additional divergence-free condition for the field variables. The edge element-based finite-element method is used to both discretize the wave equations and enforce the divergence-free condition. For wave propagation described in terms of the magnetic field in the widely used class of non-magnetic materials, the divergence-free condition is imposed on the magnetic field. This naturally leads to a nodal topology optimization method. When wave propagation is described using the electric field, the divergence-free condition must be imposed on the electric displacement. In this case, the material in the design domain is assumed to be piecewise homogeneous to impose the divergence-free condition on the electric field. This results in an element-wise topology optimization algorithm. The topology optimization problems are regularized using a Helmholtz filter and a threshold projection method and are analysed using a continuous adjoint method. In order to ensure the applicability of the filter in the element-wise topology optimization version, a regularization method is presented to project the nodal into an element-wise physical density variable.

ELECTROMAGNETIC RADIATION INDUCED BY A GRAVITATIONAL WAVE

1995 ◽  
Vol 04 (02) ◽  
pp. 207-213
Author(s):  
N.I. KOLOSNITSYN
Keyword(s):  
Gravitational Wave ◽  
Electromagnetic Waves ◽  
Maxwell Equations ◽  
Three Dimensional ◽  
Geodesic Equation ◽  
Electromagnetic Signal ◽  
The Matrix ◽  
Radiation Induced ◽  
Isotropic Geodesic ◽  
Laser Interferometric

Conversion of a gravitational wave into an electromagnetic one in a laser coherent emission field is studied. As a result two electromagnetic waves are created. For calculation the Maxwell equations in three-dimensional vector form are used. Optimal detection of the gravitational wave is discussed. In a particular case it is the laser interferometric antenna. This approach is identical to those based on integration of the isotropic geodesic equation, the eikonal equation, giving the three-pulsing response of the electromagnetic signal obtained by Estabrook and Wahlquist. It also results in the matrix method developed by Vinet for calculation of laser interferometric antennae.

Selective Transmission of Electromagnetic Wave by Using Diamond Photonic Crystals with Graded Lattice Spacing

2006 ◽  
Vol 45 ◽  
pp. 1139-1144
Author(s):  
Soshu Kirihara ◽  
Yoshinari Miyamoto
Keyword(s):  
Photonic Crystals ◽  
Band Gap ◽  
Electromagnetic Waves ◽  
Lattice Spacing ◽  
Three Dimensional ◽  
Dielectric Constants ◽  
Microwave Antenna ◽  
Diamond Structure ◽  
Band Calculation ◽  
Graded Lattice

Three-dimensional electromagnetic or photonic crystals with periodic variations of the dielectric constants were fabricated by using a rapid prototyping method called stereolithography. Millimeter-order epoxy lattices with a diamond structure were designed to reflect electromagnetic waves by forming an electromagnetic band gap in GHz range. Titania based ceramic particles were dispersed into the lattice to control the dielectric constant. The diamond lattice structures formed the perfect band gap reflecting electromagnetic waves for all directions. The location of the band gap agreed with the band calculation using the plane wave propagation method. The diamond structures with graded lattice spacing were successfully fabricated as well, resulting in the directional transmission of microwaves. The stretching ratio of the lattice spacing in the crystal structure was changed according to the electromagnetic band calculation. A microwave antenna head composed of the diamond structure with graded lattice spacing was fabricated which achieved the unidirectional transmission.

Diffraction by a plane screen

1950 ◽  
Vol 202 (1069) ◽  
pp. 277-284 ◽  
Keyword(s):  
Integral Equation ◽  
Boundary Conditions ◽  
Integral Equations ◽  
Half Plane ◽  
Arbitrary Function ◽  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Integral Equation Method ◽  
Dimensional Problem ◽  
Conducting Plane

The integral-equation method of solving the problem of the diffraction of electromagnetic waves by a perfectly conducting plane screen has been criticized by C. J. Bouwkamp, who claims that it is valid only when certain boundary conditions are satisfied on the edge of the screen. This criticism is answered. It is also shown that, since the equations to be solved are differential-integral equations, an arbitrary function arises in the solution and that this arbitrary function may be chosen so that, although there are singularities at the edge of the screen, there is no radiation of energy from the edge. As an illustration, the three-dimensional problem of diffraction by a half-plane is solved.

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