scholarly journals A distributed and iterative method for square root filtering in space-time estimation

Automatica ◽  
1995 ◽  
Vol 31 (1) ◽  
pp. 67-82 ◽  
Author(s):  
Toshio M. Chin ◽  
William C. Karl ◽  
Alan S. Willsky
Keyword(s):  
Iterative Method ◽  
Time Estimation ◽  
Space Time ◽  
Square Root

Time Estimation and Total Subjective Time

1977 ◽  
Vol 44 (2) ◽  
pp. 527-532 ◽  
Author(s):  
James L. Walker
Keyword(s):  
Life Span ◽  
Time Estimation ◽  
Chronological Age ◽  
Subjective Time ◽  
Square Root ◽  
Time Model ◽  
Subjective Duration ◽  
Retrospective Reports ◽  
Age Model ◽  
Perceived Duration

Techniques for estimation of magnitude were used in a questionnaire given to 100 university students to test the hypothesis that the subjective duration of an interval of actual time decreases in proportion to total subjective time rather than total chronological age. The results supported the subjective time hypothesis for retrospective reports of perceived duration of a year at both one-half and one-quarter of the subject's present age. In both cases the subjective time hypothesis provided a better fit to the data than the chronological age model. The hypothesis of the subjective time model that subjective life-span is equal to the square root of the statistically expected life-span was also tested but was not confirmed.

scholarly journals NEW GEOMETRIC FORMALISM FOR GRAVITY EQUATION IN EMPTY SPACE

2005 ◽  
Vol 14 (06) ◽  
pp. 1009-1022 ◽  
Author(s):  
XIN-BING HUANG
Keyword(s):  
Differential Equations ◽  
Gauge Field ◽  
Empty Space ◽  
Space Time ◽  
Gravity Theory ◽  
Spin Connection ◽  
Square Root ◽  
Field Equations ◽  
Complex Spin ◽  
Set Up

In this paper, a complex daor field which can be regarded as the square root of space–time metric is proposed to represent gravity. The locally complexified geometry is set up, and the complex spin connection constructs a bridge between gravity and SU(1, 3) gauge field. Daor field equations in empty space are acquired, which are one-order differential equations and do not conflict with Einstein's gravity theory.

scholarly journals Accurate Direction-of-Arrival Estimation Method based on Space-Time Modulated Metasurface

2022 ◽  
Author(s):  
Mengmeng Li
Keyword(s):  
Plane Wave ◽  
Incident Angle ◽  
Estimation Method ◽  
Time Estimation ◽  
Direction Of Arrival ◽  
Doa Estimation ◽  
Space Time ◽  
Estimation Methods ◽  
Estimation Accuracy ◽  
Hardware Complexity

In this paper, we present a metasurface-based Direction of Arrival (DoA) estimation method that exploits the properties of space-time modulated reflecting metasurfaces to estimate in real-time the impinging angle of an illuminating monochromatic plane wave. The approach makes use of the amplitude unbalance of the received fields at broadside at the frequencies of the two first-order harmonics generated by the interaction between the incident plane wave and the modulated metasurface. Here, we first describe analytically how to generate the desired higher-order harmonics in the reflected spectrum and how to realize the breaking of the spatial symmetry of each order harmonic scattering pattern. Then, the one dimensional (1D) omnidirectional incident angle can be analytically computed using +1st and -1st order harmonics. The approach is also extended to 2D DoA estimation by using two orthogonally arranged 1D DoA modulation arrays. The accuracy of 1D DoA estimation is verified through full-wave numerical simulations. Compared to conventional DoA estimation methods, the proposed approach simplifies the computation and hardware complexity, ensuring at the same time estimation accuracy. The proposed method may have potential applications in wireless communications, target recognition, and identification.

scholarly journals Scalar field at large distances from spherically symmetric static configuration

2019 ◽  
pp. 6-9
Author(s):  
A. Alexandrov ◽  
O. Stashko ◽  
V. Zhdanov
Keyword(s):  
Scalar Field ◽  
Iterative Method ◽  
Symmetric Space ◽  
Numerical Solution ◽  
Space Time ◽  
Spherically Symmetric ◽  
Joint System ◽  
Static Configuration ◽  
Radial Variable

Stationary spherically symmetric space-time in the quasi-global coordinates is considered in presence of scalar field (SF) minimally coupled to gravity, with a monomial potential V(ϕ)=ϕn, n>4. We prove convergence of an iterative method to solve the joint system of Einstein – SF equations at sufficiently large distances from the center. The result can be used for a numerical solution for the metric and SF by means of backwards integration from large values of the radial variable to smaller ones.

scholarly journals Accurate Direction-of-Arrival Estimation Method based on Space-Time Modulated Metasurface

2022 ◽  
Author(s):  
Mengmeng Li
Keyword(s):  
Plane Wave ◽  
Incident Angle ◽  
Estimation Method ◽  
Time Estimation ◽  
Direction Of Arrival ◽  
Doa Estimation ◽  
Space Time ◽  
Estimation Methods ◽  
Estimation Accuracy ◽  
Hardware Complexity

In this paper, we present a metasurface-based Direction of Arrival (DoA) estimation method that exploits the properties of space-time modulated reflecting metasurfaces to estimate in real-time the impinging angle of an illuminating monochromatic plane wave. The approach makes use of the amplitude unbalance of the received fields at broadside at the frequencies of the two first-order harmonics generated by the interaction between the incident plane wave and the modulated metasurface. Here, we first describe analytically how to generate the desired higher-order harmonics in the reflected spectrum and how to realize the breaking of the spatial symmetry of each order harmonic scattering pattern. Then, the one dimensional (1D) omnidirectional incident angle can be analytically computed using +1st and -1st order harmonics. The approach is also extended to 2D DoA estimation by using two orthogonally arranged 1D DoA modulation arrays. The accuracy of 1D DoA estimation is verified through full-wave numerical simulations. Compared to conventional DoA estimation methods, the proposed approach simplifies the computation and hardware complexity, ensuring at the same time estimation accuracy. The proposed method may have potential applications in wireless communications, target recognition, and identification.

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