MVDR Beamformer Design by Imposing Unit Circle Roots Constraints for Uniform Linear Arrays

2021 ◽  
Vol 69 ◽  
pp. 6116-6130
Author(s):  
Arnab Shaw ◽  
Jared Smith ◽  
Aboulnasr Hassanien
Keyword(s):  
Unit Circle ◽  
Linear Arrays ◽  
Beamformer Design

Application of the Unit Circle Representation to Pattern Synthesis of Nonuniformly Spaced and Nonuniformly Excited Arrays based on the Teaching Learning Based Optimization

2019 ◽  
Vol 4 (1) ◽  
pp. 8-17
Author(s):  
Abdelmadjid RECIOUI
Keyword(s):  
Unit Circle ◽  
Antenna Array ◽  
Communication Systems ◽  
Sidelobe Level ◽  
Pattern Synthesis ◽  
Linear Arrays ◽  
Array Pattern ◽  
Teaching Learning Based Optimization ◽  
Null Placement ◽  
Teaching Learning

Pattern synthesis of Antenna array has gained much attention over the last years as they constitute an important role in the modern communication systems. Unit circle-based techniques such as Schelkunoff null placement method have proved their effectiveness to synthesize uniformly spaced linear arrays. Nonuniformly spaced antenna array pattern synthesis has been investigated and interesting results have been obtained. In this work, the unit circle representation approach is applied to synthesize nonuniformly spaced and nonuniformly excited linear arrays. The objective is to accurately place nulls in the desired directions while achieving the least possible sidelobe level. The problem is cast as an optimization problem that is solved using the Teaching Learning Based Optimization (TLBO). Examples are dealt with to prove the design approach effectiveness and flexibility for modern communication system applications.

Linear Arrays of Helical Polyribosomes in Cells Exposed to Antitumor Drug Vincristine Sulfate

1969 ◽  
Vol 27 ◽  
pp. 358-359
Author(s):  
Awtar Krishan
Keyword(s):  
Close Association ◽  
Annulate Lamellae ◽  
Large Array ◽  
Vincristine Sulfate ◽  
Linear Arrays ◽  
Golgi Membranes ◽  
Related Drug ◽  
Drug Leads ◽  
Lethal Doses ◽  
Vinblastine Sulfate

Earle's L-929 fibroblasts treated with mitosis-arresting but sub-lethal doses of vinblastine sulfate (VLB) show hypertrophy of the granular endoplasmic reticulum and annulate lamellae. Exposure of the cells to heavier doses of vincristine sulfate (VCR), a VLB-related drug, leads to the accumulation of large amounts of helical polyribosomes, Golgi membranes and crystals in the cytoplasm. In many of these cells a large number of helical polyribosomes are arranged in prominent linear rows, some of which may be up to 5 micrometers in length. Figure 1 shows a large array of helical polyribosomes near a crystalline mass (CRS) in an Earle's L-929 fibroblast exposed to VCR (5ϒ/ml.) for 3 hours At a higher magnification, as seen in figure 2, the helical polyribosomes are seen arranged in parallel rows. In favorably cut sections, a prominent backbone like "stalk" of finely granular material, measuring approximately 300Å in width is seen in close association with the linear rows of helical polyribosomes.

The Restricted Arc-Width of a Graph

10.37236/1734 ◽  
2003 ◽  
Vol 10 (1) ◽  
Author(s):  
David Arthur
Keyword(s):  
Unit Circle ◽  
Single Point ◽  
Minimum Width ◽  
Graph Operations ◽  
Function Mapping

An arc-representation of a graph is a function mapping each vertex in the graph to an arc on the unit circle in such a way that adjacent vertices are mapped to intersecting arcs. The width of such a representation is the maximum number of arcs passing through a single point. The arc-width of a graph is defined to be the minimum width over all of its arc-representations. We extend the work of Barát and Hajnal on this subject and develop a generalization we call restricted arc-width. Our main results revolve around using this to bound arc-width from below and to examine the effect of several graph operations on arc-width. In particular, we completely describe the effect of disjoint unions and wedge sums while providing tight bounds on the effect of cones.

scholarly journals Layout optimization of heaving Wave Energy Converters linear arrays in front of a vertical wall

2021 ◽  
Author(s):  
Eva Loukogeorgaki ◽  
Constantine Michailides ◽  
George Lavidas ◽  
Ioannis K. Chatjigeorgiou
Keyword(s):  
Wave Energy ◽  
Vertical Wall ◽  
Layout Optimization ◽  
Linear Arrays ◽  
Wave Energy Converters ◽  
Energy Converters

scholarly journals A Discontinuity of the Energy of Quantum Walk in Impurities

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1134
Author(s):  
Kenta Higuchi ◽  
Takashi Komatsu ◽  
Norio Konno ◽  
Hisashi Morioka ◽  
Etsuo Segawa
Keyword(s):  
Unit Circle ◽  
Stationary State ◽  
Discrete Time ◽  
Quantum Walk ◽  
Time Limit ◽  
The Other ◽  
Unitary Matrix ◽  
Initial State ◽  
Time Quantum ◽  
Long Time

We consider the discrete-time quantum walk whose local dynamics is denoted by a common unitary matrix C at the perturbed region {0,1,⋯,M−1} and free at the other positions. We obtain the stationary state with a bounded initial state. The initial state is set so that the perturbed region receives the inflow ωn at time n(|ω|=1). From this expression, we compute the scattering on the surface of −1 and M and also compute the quantity how quantum walker accumulates in the perturbed region; namely, the energy of the quantum walk, in the long time limit. The frequency of the initial state of the influence to the energy is symmetric on the unit circle in the complex plain. We find a discontinuity of the energy with respect to the frequency of the inflow.

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