scholarly journals Analysis of RCS of Low Observable Aircraft in VHF Band

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yi-Ru Jeong ◽  
Chan-Sun Park ◽  
Young-Kwan Ko ◽  
Jong-Gwan Yook
Keyword(s):  
Method Of Moments ◽  
Cross Sections ◽  
Incident Wave ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Bistatic Radar ◽  
Three Dimensional Model ◽  
Maximum Value ◽  
Radar Cross Sections ◽  
Fast Multipole Algorithm

Electromagnetic signatures of a low observable aircraft have been studied in VHF band. First of all, a three-dimensional model of the aircraft has been established for numerical computation. Then, monostatic and bistatic radar cross sections (RCS) have been calculated. The model of the aircraft is made by a curved surface, and commercial as well as in-house three-dimensional electromagnetic code which is based on the method of moments (MoM) is utilized to calculate the RCS. A characteristic basis function method (CBFM) and a multilevel fast multipole algorithm (MLFMA) have been applied to analyze electrically large objects. The change of the monostatic RCS is very large depending on the direction of the incident wave. The maximum value is about 42 dBsm at the top and bottom of the aircraft, and the minimum value is about −10 dBsm at the front and back of the aircraft. It is found that the bistatic RCS also changes dramatically depending on the direction of the incident wave. The direction of maximum RCS occurs around specular reflection, and the value of maximum RCS ranges from 27 dBsm to 43 dBsm. On the other hand, the direction of the minimum RCS occurs irregularly, and the value is in the level of −30 dBsm.

scholarly journals Application of GO Management in Bistatic RCS Computation Using the Vector Parabolic Equation Method

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
X. J. Zhong ◽  
T. J. Cui ◽  
J. F. Zhang ◽  
W. M. Yu
Keyword(s):  
Parabolic Equation ◽  
Cross Sections ◽  
Large Scale ◽  
Three Dimensional ◽  
Original Method ◽  
Good Choice ◽  
Bistatic Radar ◽  
Large Scale Problems ◽  
Radar Cross Sections ◽  
Resultant Matrix

The parabolic equation (PE) method is a good choice in solving large-scale problems, but the resultant matrix is usually ill conditioned. In this letter, we introduce the geometric optics (GO) management in the calculation of bistatic radar cross sections using three-dimensional vector PE method. This method manages the object surface by GO, and hence the ill-conditioned problem can be avoided. Examples are given using the presented method, original method, and the method of moments. Results show the validity and stability of the presented method.

Application of Bentley Power Rail Track Software in the BIM Railway Design

2014 ◽  
Vol 587-589 ◽  
pp. 1091-1094
Author(s):  
Xi Sheng ◽  
Hua Peng Luo ◽  
Ping Wang
Keyword(s):  
Cross Sections ◽  
High Efficiency ◽  
Three Dimensional ◽  
Digital Terrain Model ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Rail Track ◽  
Terrain Model ◽  
Digital Terrain ◽  
Design Software

Belonging to the Bentley Microstation series which work as one of the BIM platforms, the Bentley Power Rail Track shows huge advantages in the railway design for its visibility, high efficiency, advance, reliability and so on. This paper introduces the way to build the digital terrain model, alignments, cross sections, turnouts and to display the three-dimensional model of the railway for the Bentley Power Rail Track 3D railway design software. It provides application preparation for the BIM railway design and achieves the preliminary exploration of BIM applications. Bentley Power Rail Track proves capable of the BIM railway design.

scholarly journals Developing the Flow Path For the K-1250-6.9/25 Turbine Unit Using the Optimal Design Methods

2021 ◽  
pp. 15-18
Author(s):  
Ihor Palkov ◽  
Sergii Palkov ◽  
Oleh Ishchenko ◽  
Olena Avdieieva
Keyword(s):  
Numerical Experiment ◽  
Cross Sections ◽  
Turbine Unit ◽  
Current Flow ◽  
Three Dimensional ◽  
Flow Path ◽  
Three Dimensional Model ◽  
Flow Paths ◽  
Intermediate Pressure ◽  
Blade System

The paper considers the main principles that are used to develop the flow paths (FP) of the high-pressure cylinders (HPC), intermediate-pressure cylinders (IPC), and low-pressure cylinders (LPC) for the K-1250-6.9/25 turbine unit. It describes approaches to the numerical experiment when designing flow paths, the advantage of which is lower labor, time and financial costs and higher informativeness compared to the physical experiment on flow paths. When designing the flow paths of high- and intermediate-pressure cylinders (HIPC), the numerical experiment is performed using the three-dimensional viscous-flow method. For this purpose, a three-dimensional model of the blade system in the flow path is built, which consists of a large number of finite volumes (elements) in the shape of hexagons, in each of which the integration of the equations of gas dynamics is performed. When developing LPC, the method of parameterization and analytical profiling of the blade crown sections is used, where the profiles are described by the curves of the fourth and fifth orders with the condition of providing the minimum value of the maximum curvature and monotonicity of variation of the three-dimensional blade geometry along height. This method allows obtaining the optimal profiles of the cross sections of the blades, which correspond to the current flow lines to the fullest extent, and minimizing the profile energy losses when the flow flows around the blades.

Image processing algorithms in the assessment of grain damage degree

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wojciech Maliga ◽  
Włodzimierz Dudziński ◽  
Magdalena Łabowska ◽  
Jerzy Detyna ◽  
Marcin Łopusiewicz ◽  
...  
Keyword(s):  
Image Processing ◽  
Cross Sections ◽  
Three Dimensional ◽  
Sample Volume ◽  
Three Dimensional Model ◽  
Time Intervals ◽  
Damage Degree ◽  
Grain Damage ◽  
Analyse Sample

Abstract Objectives The paper presents preliminary results on the assessment of algorithms used in image processing of the grain damage degree. The purpose of the work is developing a tool allowing to analyse sample cross-sections of rye germs. Methods The analysis of the grain cross-sections was carried out on the basis of a series their photos taken at equal time intervals at a set depth. The cross-sections will be used to create additional virtual cross-sections allowing to analyse the whole sample volume. The ultimate plan is to generate two cross-sections perpendicular to each other. Based on volumetric data read from the sample section, a three-dimensional model of an object will be generated. Results The analysis of model surface will allowed us to detect possible grain damage. The developed method of preparing the research material and the proprietary application allowed for the identification of internal defects in the biological material (cereal grains). Conclusions The presented methodology may be used in the agri-food industry in the future. However, much research remains to be done. These works should primarily aim at significantly reducing the time-consuming nature of individual stages, as well as improving the quality of the reconstructed image.

scholarly journals Prediction of the spatial variability of coal-bearing rocks at the Elginsky coal mine

2020 ◽  
Vol 192 ◽  
pp. 04007
Author(s):  
Yuri Malinin ◽  
Nikolai Grib ◽  
Pavel Kuznetsov ◽  
Zhang Ze
Keyword(s):  
Spatial Variability ◽  
Cross Sections ◽  
Coal Mine ◽  
Three Dimensional ◽  
Spatial Modelling ◽  
Ash Content ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Markov Modelling ◽  
Composition Structure

The article presents a brief analysis of the key methods used for spatial modelling of mining and geological indicators describing the composition, structure and state of rock deposits. The main limitations of the analysed methods when applied under real conditions are outlined. It is proposed to overcome these limitations using Markov nonlinear algorithms. By applying the principles of multi-dimensional Markov modelling to a geological object, interval types were determined for modelling mining and geological parameters of the Elginsky coal mine. As an example, the article presents the results of predicting the ash content for the U5 section of the Elginsky coal mine on the basis of one of the cross-sections of the developed three-dimensional model.

scholarly journals The Investigation of EM Scattering from the Time-Varying Overturning Wave Crest Model by the IEM

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Xiao Meng ◽  
Li-xin Guo ◽  
Tian-qi Fan
Keyword(s):  
Cross Sections ◽  
3D Model ◽  
Three Dimensional ◽  
Integral Equation Method ◽  
Wave Crest ◽  
Time Varying ◽  
Spike Generation ◽  
Horizontal Polarization ◽  
Em Scattering ◽  
Radar Cross Sections

Investigation of the electromagnetic (EM) scattering of time-varying overturning wave crests is a worthwhile endeavor. Overturning wave crest is one of the reasons of sea spike generation, which increases the probability of false radar alarms and reduces the performance of multitarget detection in the environment. A three-dimensional (3D) time-varying overturning wave crest model is presented in this paper; this 3D model is an improvement of the traditional two-dimensional (2D) time-varying overturning wave crest model. The integral equation method (IEM) was employed to investigate backward scattering radar cross sections (RCS) at various incident angles of the 3D overturning wave crest model. The super phenomenon, where the intensity of horizontal polarization scattering is greater than that of vertical polarization scattering, is an important feature of sea spikes. Simulation results demonstrate that super phenomena may occur in some time samples as variations in the overturning wave crest.

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