Holographic wave front printing for fabrication of reflection holograms with arbitrary recording wave fronts

2020 ◽  
Author(s):  
Johannes Hofmann ◽  
Reinhold Fiess ◽  
Wilhelm Stork
Keyword(s):  
Wave Front ◽  
Wave Fronts

scholarly journals Wave Fronts in a Causality-Violating Gödel-Type Metric

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Thomas P. Kling ◽  
Faizuddin Ahmed ◽  
Megan Lalumiere
Keyword(s):  
Wave Front ◽  
Space Time ◽  
Wave Fronts ◽  
Light Rays ◽  
Synchronized Clocks

The light rays and wave fronts in a linear class of the Gödel-type metric are examined to reveal the causality-violating features of the space-time. Noncausal features demonstrated by the development of unusual wave front singularities are shown to be related to the nonmonotonic advance of time along the light rays, as measured by a system of observers at rest with respect to one another with synchronized clocks.

scholarly journals Analysis of a self-centring detonation wave generator

2021 ◽  
pp. 34-47
Author(s):  
Waldemar Trzciński ◽  
Józef Paszula ◽  
Leszek Szymańczyk
Keyword(s):  
Theoretical Analysis ◽  
Detonation Wave ◽  
Wave Front ◽  
Point Location ◽  
Wave Fronts ◽  
Initiation Point ◽  
X Ray ◽  
Detonation Wave Front ◽  
Main Charge ◽  
Wave Generator

The aim of the study was to determine the parameters of a detonator generating a self-centring detonation wave, based on experimental and theoretical analysis. The methods for manufacturing selfcentring detonation wave generators available in literature were reviewed and a detonator comprised of two explosives was proposed. The detonator geometry was analysed for its ability to centre the detonation wave. A physical detonator model was created and the detonation wave front downstream of the detonator, analysed and the detonator’s capability to compensate an off-centre detonation initiation, evaluated. The wave fronts were recorded using pulsed x-ray radiography. The study showed that the proposed detonator provides a symmetrical initiation of the main charge for the initiation point (location) offset, lower than the assumed maximum offset.

scholarly journals Characterization of Wave Fronts of Ultradistributions Using Directional Short-Time Fourier Transform

Axioms ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 240
Author(s):  
Sanja Atanasova ◽  
Snježana Maksimović ◽  
Stevan Pilipović
Keyword(s):  
Fourier Transform ◽  
Wave Front ◽  
Short Time Fourier Transform ◽  
Wave Fronts ◽  
Directional Wave ◽  
Tempered Ultradistributions ◽  
Short Time

In this paper we give a characterization of Sobolev k-directional wave front of order p∈[1,∞) of tempered ultradistributions via the directional short-time Fourier transform.

scholarly journals Null Wave Front and Ryu–Takayanagi Surface

Entropy ◽  
2020 ◽  
Vol 22 (11) ◽  
pp. 1297
Author(s):  
Jun Tsujimura ◽  
Yasusada Nambu
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Cosmological Constant ◽  
Minimal Surface ◽  
Wave Front ◽  
Entanglement Entropy ◽  
Necessary Condition ◽  
Quantum Field ◽  
Wave Fronts ◽  
Sufficient And Necessary Condition

The Ryu–Takayanagi formula provides the entanglement entropy of quantum field theory as an area of the minimal surface (Ryu–Takayanagi surface) in a corresponding gravity theory. There are some attempts to understand the formula as a flow rather than as a surface. In this paper, we consider null rays emitted from the AdS boundary and construct a flow representing the causal holographic information. We present a sufficient and necessary condition that the causal information surface coincides with Ryu–Takayanagi surface. In particular, we show that, in spherical symmetric static spacetimes with a negative cosmological constant, wave fronts of null geodesics from a point on the AdS boundary become extremal surfaces and therefore they can be regarded as the Ryu–Takayanagi surfaces. In addition, from the viewpoint of flow, we propose a wave optical formula to calculate the causal holographic information.

Meandering and unstable reentrant wave fronts induced by acetylcholine in isolated canine right atrium

1997 ◽  
Vol 273 (1) ◽  
pp. H356-H370 ◽  
Author(s):  
T. Ikeda ◽  
T. J. Wu ◽  
T. Uchida ◽  
D. Hough ◽  
M. C. Fishbein ◽  
...  
Keyword(s):  
Wave Front ◽  
Current Strength ◽  
Right Atrial ◽  
New Wave ◽  
Wave Fronts ◽  
Bipolar Electrodes ◽  
Upper Limit Of Vulnerability ◽  
Before And After ◽  
Simultaneous Decrease ◽  
Front Dynamics

The mechanism(s) by which acetylcholine (ACh) increases atrial vulnerability to reentry and maintains its activity for longer durations remains poorly defined. In the present study we used high-resolution activation maps to test the hypothesis that ACh promotes meandering of atrial reentrant wave fronts, resulting in breakup and the generation of new wave fronts that sustain the activity. Reentry was induced in 11 isolated canine right atrial tissues (3.8 x 3.2 cm) by a premature point stimulus (S2) before and after superfusion with ACh (15 x 10(-6) M). Endocardial isochronal activation maps were constructed with the use of 509 bipolar electrodes (1.6-mm spatial resolution), and the dynamics of the activation wave fronts were visualized with animation. A vulnerable period was found during which an S2 current strength > 4.4 +/- 2.5 mA [lower limit of vulnerability (LLV)] and < 26 +/- 13 mA [upper limit of vulnerability (ULV)] induced a single stationary reentrant wave front that lasted 3 +/- 2.5 s with a period of 159 +/- 17 ms (16 episodes). AC shortened the refractory period from 100 +/- 12 to 59 +/- 9 ms (P < 0.001) and increased vulnerability to reentry induction by simultaneous decrease in the LLV (0.7 +/- 0.2 mA, P < 0.001) and an increase in the ULV (82 +/- 24 mA, P < 0.01). ACh accelerated the rate (period of 110 +/- 16 ms, P < 0.001) and converted the stationary reentrant wave front to a nonstationary (meandering) reentrant wave front showing polymorphic electrograms, i.e., “fibrillation-like” activity (22 episodes). Rapid meandering of the reentry tip led to wave front breakup (18 episodes) and the generation of new wave fronts (19 episodes). These wave front dynamics also led to sustained (76 +/- 224 s, P < 0.001) fibrillation-like electrograms. We conclude that ACh increases the ULV and promotes meandering of a single reentrant wave front, leading to breakup and the generation of new wave fronts. Single meandering and complex wave front dynamics cause fibrillation-like activity and sustain the activity for longer duration.

On diffracted wave fronts

1979 ◽  
Vol 84 (1-2) ◽  
pp. 35-54
Author(s):  
Peter Wolfe
Keyword(s):  
Wave Equation ◽  
Wave Front ◽  
Incident Wave ◽  
Spherical Wave ◽  
Small Time ◽  
Time Interval ◽  
Wave Fronts ◽  
Incident Plane ◽  
Small Time Interval ◽  
Propagation Of Singularities

SynopsisIn this paper we study the wave equation, in particular the propagation of discontinuities. Two problems are considered: diffraction of a normally incident plane pulse by a plane screen and diffraction of a spherical wave by the same screen. It is shown that when an incident wave front strikes the edge of the screen a diffracted wave front is produced. The discontinuities are precisely computed in a neighbourhood of the edge for a small time interval after the arrival of the incident wave front and a theorem of Hörmander on the propagation of singularities is used to obtain a globalresult.

A TRANSFORMED WAVE‐FRONT CHART

Geophysics ◽  
1941 ◽  
Vol 6 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Raymond A. Peterson
Keyword(s):  
Wave Front ◽  
Wave Fronts ◽  
Velocity Increase ◽  
Cartesian Coordinates ◽  
Uniform Rate ◽  
Wave Path ◽  
Concentric Circles

In seismograph computations assuming a uniform rate of velocity increase with depth, a “wave front‐wave path” chart consisting of sets of orthogonal circles is often used. The present paper describes a transformation by which the wave fronts become a set of concentric circles with the wave paths as radii, while the cartesian coordinates representing vertical and horizontal distances in the ground become orthogonal circles.

On Wave Propagation in Thermoplastic Media

1966 ◽  
Vol 33 (3) ◽  
pp. 514-520 ◽  
Author(s):  
A. D. Fine ◽  
H. Kraus
Keyword(s):  
Wave Propagation ◽  
Closed Form ◽  
Wave Front ◽  
Dynamic Behavior ◽  
Static Analysis ◽  
Equations Of Motion ◽  
Normal Velocity ◽  
Wave Fronts ◽  
Closed Form Solutions ◽  
Infinite Region

The dynamic behavior of a medium, according to the uncoupled thermoplastic theory, is presented and is compared to the behavior that would be obtained from an uncoupled quasi-static analysis. Since the inertia terms are retained in the equations of motion, wave fronts (or surfaces of discontinuity) are produced in the medium. The normal velocity of the wave front separating the elastic and plastic regions is determined. General closed-form solutions of the displacement (according to both the dynamic and the quasi-static approaches) are obtained; their unique forms are found for the semi-infinite region, and an illustrative numerical example is then presented.

Understanding Line Packing in Frictional Water Hammer

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Jim C. P. Liou
Keyword(s):  
Numerical Methods ◽  
Wave Front ◽  
Water Hammer ◽  
Maximum Pressure ◽  
Valve Closure ◽  
Governing Equations ◽  
Front Line ◽  
Wave Fronts ◽  
Friction Term

For valve closure transients in pipelines, friction attenuates the amplitude of water hammer wave fronts and causes line packing. The latter is a sustained head increase behind the wave front. Line packing can lead to overpressure. Because of the nonlinearity of the friction term in the governing equations of water hammer, a satisfactory analytical explanation of line packing is not available. Although numerical methods can be used to compute line packing, an analytical explanation is desirable to better understand the phenomenon. This paper explains line packing analytically and presents a formula to compute the line packing that leads to the maximum pressure at the closed valve.

On the possibility of turbulent thickening of weak shock waves

1973 ◽  
Vol 58 (3) ◽  
pp. 461-480 ◽  
Author(s):  
J. E. Ffowcs Williams ◽  
M. S. Howe
Keyword(s):  
Shock Waves ◽  
Wave Packet ◽  
Wave Front ◽  
Atmospheric Turbulence ◽  
Upper Bound ◽  
Weak Shock ◽  
Sonic Boom ◽  
Wave Fronts ◽  
Sharp Wave ◽  
Nominal Position

This paper examines the possible thickening of an initially sharp sonic boom by the turbulence it encounters in passing to the ground. Three apparently different viewpoints, all indicating substantial thickening, are shown to be actually identical and to give an irrelevant upper bound on wave thickness. All three approaches describe only the apparent mean diffusion induced by random convection of a sharp wave about its nominal position. Although a wave-front folding mechanism ultimately accounts for an apparent thickening as individual rays are weakened and tangled by turbulence, this process is too slow to be effective in the practical boom situation. The paper then considers what linear thickening of a wave packet results from propagation trough atmospheric turbulence and concludes that, in the relevant limit, a wave may be thickened by a factor of about 2 at the most. The conclusion is therefore reached that atmospheric turbulence cannot be the cause of the thousandfold discrepancy between the measured wave fronts and their Taylor thickness.

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