scholarly journals AOA-Based Three-Dimensional Positioning and Tracking Using the Factor Graph Technique

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1400
Author(s):  
Haiyang Zhang ◽  
Zhiwei Zhang
Keyword(s):  
A Priori ◽  
Three Dimensional ◽  
Factor Graph ◽  
Angle Of Arrival ◽  
Target Movement ◽  
Distributed Sensors ◽  
Target State ◽  
3D Space ◽  
Observation Process ◽  
Priori Information

In this paper, an angle-of-arrival (AOA)-based algorithm is proposed for tracking the position of an anonymous target in three-dimensional (3D) space. Distributed sensors are deployed, which can measure both the azimuth and elevation angles of the AOAs. Assuming the target movement is non-linear, the extended Kalman filter (EKF) is applied, where the observation process is realized by a practical AOA-based position detector, to form a unified factor graph (FG) framework. Moreover, the variance of observation errors, which is needed by EKF, is estimated in real time by using both the AOA measurements and the predicted target state. Such a dynamic estimating approach exhibits higher performance robustness compared to the conventional method, especially when the sensing environment is unstable. Additionally, the predicted target state is also used as the a priori information of the system, in order to reduce the impacts of burst sensing errors. According to the simulations, the proposed system is shown to achieve less root mean squared errors (RMSE) in different evaluation scenarios, with fast convergence behavior.

Interpolation of Missing Part of Human Follicle Border on Ultrasonic B-Mode Image by Iterative Revision

2000 ◽  
Vol 22 (2) ◽  
pp. 108-122
Author(s):  
Y. Yamakoshi ◽  
M. Takemoto ◽  
N. Shinozuka
Keyword(s):  
Ovarian Follicle ◽  
A Priori ◽  
Three Dimensional ◽  
Closed Curve ◽  
Smoothness Condition ◽  
A Priori Information ◽  
Follicle Growth ◽  
Cross Sectional ◽  
Geometrical Characteristics ◽  
Priori Information

In clinical infertility treatments, assessment of ovarian follicle growth by ultrasonography is important. In order to measure the geometrical characteristics of the human follicle, such as the area of the cross-sectional image and the volume inside the follicle, a method based on manual tracing of the follicle contour from the ultrasonic B mode image is widely used. However, the observable ultrasonic B mode images are sometimes imperfect and some parts of the follicle border are missing due to the existence of the acoustic shadow. In this paper, a method that interpolates the missing part of the follicle border from the known part is proposed. This method uses a priori information of the follicle, which is usually known in actual cases: (1) the follicle's surface is so smooth that its border is assumed to be a smooth closed curve; and (2) the position of the follicle's center is roughly predicted in advance in the ultrasonic B-mode image. In the proposed method, the missing part of the human follicle border is interpolated from the known part by applying an iterative revision so as to satisfy the smoothness condition of the follicle. This method is also applied to three-dimensional image reconstruction of the human follicle.

THE EQUILIBRIUM THERMODYNAMICS OF VARIOUS PEPTIDE SEQUENCES

2004 ◽  
Vol 15 (04) ◽  
pp. 583-593 ◽  
Author(s):  
FATİH YAŞAR
Keyword(s):  
Specific Heat ◽  
A Priori ◽  
Three Dimensional ◽  
Helical Structure ◽  
Spectroscopic Techniques ◽  
A Priori Information ◽  
Fourth Order Cumulant ◽  
Priori Information ◽  
Α Helix ◽  
Two Peaks

The equilibrium thermodynamic properties of two peptide sequences of β-casein in the α-helix regions were studied by three-dimensional molecular modeling in vacuum. All the three-dimensional conformations of each peptide sequences were obtained by multicanonical simulations using ECEPP/2 force field and each simulation was started from completely random initial conformation. No a-priori information about ground-state is used in the simulations. In the present study, we calculated the average values of total energy, specific heat, fourth-order cumulant for two peptide sequences of β-casein as a function of temperature. We observed that the specific heat shows two peaks as a function of temperature for both peptides. Because our sequences have highly helical structure and two peaks in the specific heat, we have also studied the helix–coil transitions to determine these peaks. Our data indeed show these peptides have highly helical structure and better agreement with the results of spectroscopic techniques and other prediction methods.

scholarly journals TOMOGRAPHY BASED ON THE REPRESENTATION OF THE MODEL BY CHIBYSHEV POLYNOMIALS: EXAMPLES OF USE

2019 ◽  
Vol 2 (3) ◽  
pp. 154-159
Author(s):  
Maxim Protasov ◽  
Dmitry Neklyudov ◽  
Leonid Nazarov
Keyword(s):  
Rock Mass ◽  
Ray Tracing ◽  
Efficient Algorithm ◽  
A Priori ◽  
Three Dimensional ◽  
Stress Fields ◽  
A Priori Information ◽  
Travel Time Tomography ◽  
Coal Rock ◽  
Priori Information

The paper deals with the three-dimensional travel-time tomography of the first arrivals. The model is represented by Chebyshev polynomials. This allows one to use a priori information about the model effectively and reduce the number of recoverable parameters to the required minimum. Also, such a model representation makes it possible to obtain a very efficient algorithm for solving the two-point ray-tracing problem for three-dimensional media, which is necessary for tomography. Examples of solving the three-dimensional cross-well tomography, as well as examples using tomography for the reconstruction of stress fields in the coal-rock mass are presented.

scholarly journals Optimal 3D Angle of Arrival Sensor Placement with Gaussian Priors

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1379
Author(s):  
Rongyan Zhou ◽  
Jianfeng Chen ◽  
Weijie Tan ◽  
Qingli Yan ◽  
Chang Cai
Keyword(s):  
Optimization Problem ◽  
Target Location ◽  
Mean Squared Error ◽  
Information Matrix ◽  
Sensor Placement ◽  
Three Dimensional ◽  
Invariance Property ◽  
Angle Of Arrival ◽  
3D Space ◽  
Sensor Placement Optimization

Sensor placement is an important factor that may significantly affect the localization performance of a sensor network. This paper investigates the sensor placement optimization problem in three-dimensional (3D) space for angle of arrival (AOA) target localization with Gaussian priors. We first show that under the A-optimality criterion, the optimization problem can be transferred to be a diagonalizing process on the AOA-based Fisher information matrix (FIM). Secondly, we prove that the FIM follows the invariance property of the 3D rotation, and the Gaussian covariance matrix of the FIM can be diagonalized via 3D rotation. Based on this finding, an optimal sensor placement method using 3D rotation was created for when prior information exists as to the target location. Finally, several simulations were carried out to demonstrate the effectiveness of the proposed method. Compared with the existing methods, the mean squared error (MSE) of the maximum a posteriori (MAP) estimation using the proposed method is lower by at least 25% when the number of sensors is between 3 and 6, while the estimation bias remains very close to zero (smaller than 0.15 m).

scholarly journals Approximation approach in various modifications of the method of linear integral representations

2019 ◽  
pp. 31-46
Author(s):  
I. E. Stepanova ◽  
I. A. Kerimov ◽  
A. G. Yagola
Keyword(s):  
Inverse Problems ◽  
Dimensional Space ◽  
Arbitrary Dimension ◽  
A Priori ◽  
Three Dimensional ◽  
Integral Representations ◽  
Algebraic Equations ◽  
Approximation Approach ◽  
Priori Information ◽  
Linear Integral

The specificity of applying the approximation approach to solving the linear and nonlinear inverse problems of geophysics, geodesy, and geomorphology is discussed. Within the paradigm proposed by V.N. Strakhov, practically all geophysical problems can be reduced to the systems of linear (and, in some cases, nonlinear) algebraic equations. The method of integral representations is the main one for implementing this approach.The application of various modifications of the method of linear integral representations in the spaces of arbitrary dimension is analyzed. Based on the combined approximations of the topography and geopotential fields, it is possible to determine the optimal parameters of the method for solving a broad range of inverse problems of geophysics and geomorphology and to most fully use the a priori information about the elevations and the elements of the anomalous fields. The method for numerical solving the inverse problem on the distributions of carriers of mass equivalent in terms of the external field in the ordinary three-dimensional space and in the four-dimensional space is described.

Innovative Approach to Information Search by Example of a Patent Analysis of an Important Substitution Plan

2020 ◽  
pp. 143-157
Author(s):  
Maria A. Milkova
Keyword(s):  
Information Search ◽  
Topic Modeling ◽  
Cognitive Biases ◽  
A Priori ◽  
Import Substitution ◽  
Innovative Approach ◽  
Iterative Search ◽  
Comprehensive Picture ◽  
Priori Information ◽  
Selection Of

Nowadays the process of information accumulation is so rapid that the concept of the usual iterative search requires revision. Being in the world of oversaturated information in order to comprehensively cover and analyze the problem under study, it is necessary to make high demands on the search methods. An innovative approach to search should flexibly take into account the large amount of already accumulated knowledge and a priori requirements for results. The results, in turn, should immediately provide a roadmap of the direction being studied with the possibility of as much detail as possible. The approach to search based on topic modeling, the so-called topic search, allows you to take into account all these requirements and thereby streamline the nature of working with information, increase the efficiency of knowledge production, avoid cognitive biases in the perception of information, which is important both on micro and macro level. In order to demonstrate an example of applying topic search, the article considers the task of analyzing an import substitution program based on patent data. The program includes plans for 22 industries and contains more than 1,500 products and technologies for the proposed import substitution. The use of patent search based on topic modeling allows to search immediately by the blocks of a priori information – terms of industrial plans for import substitution and at the output get a selection of relevant documents for each of the industries. This approach allows not only to provide a comprehensive picture of the effectiveness of the program as a whole, but also to visually obtain more detailed information about which groups of products and technologies have been patented.

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