scholarly journals Pseudo-Random Sequence (PRS) (Space)Time-Modulated Metasurfaces

2021 ◽  
Author(s):  
Xiaoyi Wang ◽  
Christophe Caloz
Keyword(s):  
State Transition ◽  
Random Sequence ◽  
Space Time ◽  
Spatial Multiplexing ◽  
Transient Time ◽  
Time Variance ◽  
The Media ◽  
The Waves ◽  
Secured Communication ◽  
Modulation Regime

This paper presents a novel class of (space)time-modulated metasurfaces, namely (space)time metasurfaces that are modulated by pseudo-random sequence (PRS) waveforms. In contrast to their harmonically or quasi-harmonically modulated counterparts, these metasurfaces massively alter the temporal spectrum of the waves that they process; as a result, they exhibit distinct properties and offer complementary applications. These metasurfaces are assumed here to operate in the `slow-modulation' regime, where the fixed-state time between state-transition is much larger than the transient time associated with the dispersion of the media involved, which allows safe separation of the time-variance and frequency-dispersive effects of the system. Thanks to the special properties of their modulation, which are generally assumed to have a staircase shape and to be periodic in addition to being pseudo-random, the PRS (space)time-modulated metasurfaces can perform a number of unique operations, such as spectrum spreading, interference suppression, and row/cell selection. These properties, combined with modern microwave CMOS technologies, lead to applications with unique performance or/and features, such as electromagnetic stealth, secured communication, direction of arrival estimation, and spatial multiplexing.

The Tale of Fabled Creatures

2021 ◽  
pp. 215-233
Author(s):  
M. Nur Erdem
Keyword(s):  
Digital Media ◽  
Daily Life ◽  
Space Time ◽  
Point Of View ◽  
The Other ◽  
Other Hand ◽  
The Media ◽  
The Subject ◽  
Physical Beauty

Violence has been a part of daily life in both traditional and digital media. Consequently, neither the existence of violence in the media nor the debates on this subject are new. On the other hand, the presentation of violence in fictional content should be viewed from a different point of view, especially in the context of aesthetization. Within this context, in this chapter, the serial of Penny Dreadful is analyzed. As analyzing method, Tahsin Yücel's model of the “space/time coordinates of narrative” is used. And the subject of “aestheticization of violence” is analyzed through a serial with the elements of person, space, and time. Thus, the role of not only physical beauty but also different components in the aestheticization of violence is examined.

scholarly journals The total reflexion of electric waves the interface between two media

1929 ◽  
Vol 123 (792) ◽  
pp. 391-400
Keyword(s):  
Plane Surface ◽  
Plane Waves ◽  
Reflected Waves ◽  
Total Reflexion ◽  
The Media ◽  
Velocity Of Propagation ◽  
Shadow It ◽  
The Waves ◽  
Finite Extent ◽  
Electric Waves

The theory of total reflexion has been treated usually by considering a train of plane waves incident on a plane surface separating two different media. It has been observed by Schuster that there is the difficulty of seeing how the disturbance in the second medium is maintained, and he has discussed the problem of a parallel beam of waves of finite extent incident on the plane surface separating the media. It may be noticed that there is a similar difficulty in the case where there are both transmitted and reflected waves, as there is a transfer of energy in the second medium parallel to the interface at a rate which is in the ratio σ' tan θ'/σ tan θ to the rate of transfer of energy in the first medium parallel to the interface. If the source of the electric waves in the first medium is a simple oscillator, and the velocity of propagation in the second medium is greater than the velocity of propagation in the first medium, then the rays which are bounded by the cone, whose vertex is at the oscillator, and whose semi-vertical angle is the critical angle, are transmitted into the second medium, where their boun­dary is the position of the plane interface outside the base of the cone, and there is no portion of the space in shadow. To obtain a shadow it is necessary that the interface is concave towards the oscillator. It is proposed in the following to discuss the problem of the transmission and reflexion of electric waves, when the surface separating the media is a sphere, and the source of the waves is a simple oscillator inside the sphere, whose axis passes through the centre of the sphere.

Fourth-Order Statistics for Blind Classification of Spatial Multiplexing and Alamouti Space-Time Block Code Signals

2013 ◽  
Vol 61 (6) ◽  
pp. 2420-2431 ◽  
Author(s):  
Y. A. Eldemerdash ◽  
M. Marey ◽  
O. A. Dobre ◽  
G. K. Karagiannidis ◽  
R. Inkol
Keyword(s):  
Order Statistics ◽  
Fourth Order ◽  
Block Code ◽  
Space Time ◽  
Spatial Multiplexing ◽  
Time Block ◽  
Space Time Block Code
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