Study on Effect of Shipborne Missile Launch Position Based on Fast Fourier Transform

2013 ◽  
Vol 427-429 ◽  
pp. 1653-1657
Author(s):  
Zhou Zhong ◽  
Yi Jiang ◽  
Chong Zhang ◽  
Yong Yuan Li
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Spectrum Analysis ◽  
Research Result ◽  
Integrative Model ◽  
Weapon System ◽  
Flexible Coupling ◽  
Scripting Language ◽  
Motion Characteristics ◽  
The Relationship

In allusion to the problem of launching precision, it carried on the research of the effect of shipborne missile launch position based on the spectrum analysis technology. A rigid-flexible coupling integrative model of ship movement and missile launch was built by use of virtual prototype technology. Simulation analyses on a variety of conditions were automatic conducted by launch time parameterized scripting language, and missile muzzle attitude parameters of different launch position were gained. By using of spectrum analysis which is based on FFT, the missile dynamic responsive was analyzed, and the relationship between launch position and accuracy was established. Then the position of the weapon system can be designed according to the specific motion characteristics of ship. The research result is also constructive to the selecting of suitable launch position.

scholarly journals A study of acoustic characteristics of voluntary expiratory sounds produced before and immediately after swallowing

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Shoma Hattori ◽  
Shinji Nozue ◽  
Yoshiaki Ihara ◽  
Koji Takahashi
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Time Window ◽  
Maximum Amplitude ◽  
Comparison Method ◽  
Window Length ◽  
Acoustic Characteristics ◽  
The Mean ◽  
Time Waveform ◽  
The Relationship

AbstractTo evaluate the expiratory sounds produced during swallowing recorded simultaneously with videofluorographic examination of swallowing (VF) using fast Fourier transform (FFT), and to examine the relationship between dysphagia and its acoustic characteristics. A total of 348 samples of expiratory sounds were collected from 61 patients with dysphagia whose expiratory sounds were recorded during VF. The VF results were evaluated by one dentist and categorized into three groups: safe group (SG), penetration group (PG), and aspiration group (AG). The duration and maximum amplitude of expiratory sounds produced were measured as the domain characteristics on the time waveform of these sounds and compared among the groups. Time window-length appropriate for FFT and acoustic discriminate values (AD values) of SG, PG, and AG were also investigated. The groups were analyzed using analysis of variance and Scheffé's multiple comparison method. The maximum amplitude of SG was significantly smaller than those of PG and AG. The mean duration in SG (2.05 s) was significantly longer than those in PG (0.84 s) and AG (0.96 s). The AD value in SG was significantly lower than those in PG and AG. AD value detects penetration or aspiration, and can be useful in screening for dysphagia.

scholarly journals Prediction of Monsoon Rain for the Year 2018 for Marathawada India

2018 ◽  
Author(s):  
Anand M. Sharan
Keyword(s):  
Time Series ◽  
Fourier Transform ◽  
Regression Analysis ◽  
Fast Fourier Transform ◽  
Spectrum Analysis ◽  
Rainfall Data ◽  
Series Method ◽  
Statistical Regression ◽  
Periodic Analysis ◽  
Time Series Method

In this work the rainfall in Marathawada, an area with extremely small amount of rain has been calculated based on rainfall data of last 32 years going back to 1986. The calculations have been performed using the Time Series method and Fast Fourier Transform (FFT) method. In the first method, statistical regression analysis has been carried out whereas in the second method, the rain pattern is fitted with Fourier periodic analysis. The results of these two methods are averaged for better reliability. The rainfall data is further analyzed using rainfall spectrum analysis.

Multi-Symplectic Fourier Pseudospectral Method for the Kawahara Equation

2014 ◽  
Vol 16 (1) ◽  
pp. 35-55 ◽  
Author(s):  
Yuezheng Gong ◽  
Jiaxiang Cai ◽  
Yushun Wang
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Pseudospectral Method ◽  
Kawahara Equation ◽  
Fourier Pseudospectral Method ◽  
Numerical Examples ◽  
Fourier Pseudospectral ◽  
Energy And Momentum ◽  
The Relationship ◽  
Pseudospectral Scheme

AbstractIn this paper, we derive a multi-symplectic Fourier pseudospectral scheme for the Kawahara equation with special attention to the relationship between the spectral differentiation matrix and discrete Fourier transform. The relationship is crucial for implementing the scheme efficiently. By using the relationship, we can apply the Fast Fourier transform to solve the Kawahara equation. The effectiveness of the proposed methods will be demonstrated by a number of numerical examples. The numerical results also confirm that the global energy and momentum are well preserved.

The Effect of Anisotropy on the Percolation Threshold of Sealing Surfaces

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Zhimeng Yang ◽  
Jianhua Liu ◽  
Xiaoyu Ding ◽  
Feikai Zhang
Keyword(s):  
Fourier Transform ◽  
Theoretical Result ◽  
Fast Fourier Transform ◽  
Percolation Threshold ◽  
Rough Surface ◽  
Conjugate Gradient ◽  
Surface Anisotropy ◽  
Sealing Performance ◽  
The Relationship ◽  
Theoretical Results

The percolation threshold strongly affects sealing performance. This paper investigates the relationship between the percolation threshold and the rough surface anisotropy, which is represented by the Peklenik number, γ. A series of anisotropic rough surfaces were generated and the conjugate gradient-fast Fourier transform (CG-FFT) method was used to determine the percolation threshold. The percolation threshold was found to be A/A0≈0.484±0.009 (averaged over 45 surfaces) was established for an isotropic rough surface (γ=1). Furthermore, it was also found that the percolation threshold decreased from A/A0≈0.528±0.011 to A/A0≈0.431±0.008 as 1/γ increased from 0.6 to 2. Our results differ from the theoretical result of Persson et al., where A/A0=γ/(1+γ). Comparing our calculated results with the theoretical results established the presence of an intersection value of 1/γ that was related to the effect of elastic deformation on the percolation threshold. When 1/γ was smaller than the intersection value, our calculated results were lower than the theoretical ones; and when 1/γ was greater than the intersection value, our calculated results were higher than the theoretical ones.

Motor Fault Diagnosis Based on Wavelet Analysis and Fast Fourier Transform

2011 ◽  
Vol 301-303 ◽  
pp. 1401-1405
Author(s):  
Qing Xin Zhang ◽  
Jin Li ◽  
Hai Bin Li ◽  
Chong Liu
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Frequency Spectrum ◽  
Spectrum Analysis ◽  
Traditional Method ◽  
Engineering Application ◽  
Frequency Spectrum Analysis ◽  
Stator Current ◽  
Frequency Components ◽  
Fault Characteristic

For the detection of the broken-bar fault of rotor in motors, a traditional method is frequency spectrum analysis for the stator current. However, the frequency components representative of the rotor fault can be easily submerged by the fundamental frequency, so that the detections results are inaccurate. In this paper, the stator current will be decomposed and reconstructed, after that the fast Fourier transform can be applied to the frequency spectrum analysis. It eliminates the influence that the fault characteristic components are flooded by the basic frequency components. The experiment result shows that the existence of a slight fault in rotor can be detected. The method has a good theoretical and engineering application.

Aqueous contaminant detection via UiO-66 thin film optical fiber sensor platform with fast Fourier transform based spectrum analysis

2017 ◽  
Vol 51 (2) ◽  
pp. 025601 ◽  
Author(s):  
Marziyeh Nazari ◽  
Marta Rubio-Martinez ◽  
Ravichandar Babarao ◽  
Adel Ayad Younis ◽  
Stephen F Collins ◽  
...  
Keyword(s):  
Thin Film ◽  
Fourier Transform ◽  
Optical Fiber ◽  
Fast Fourier Transform ◽  
Spectrum Analysis ◽  
Optical Fiber Sensor ◽  
Fiber Sensor ◽  
Contaminant Detection ◽  
Sensor Platform

The Research and Improvement of APFFT Algorithm

2012 ◽  
Vol 532-533 ◽  
pp. 1841-1845
Author(s):  
Jie Tao Diao ◽  
Jing Guo ◽  
Nan Li ◽  
Wei Yi ◽  
Sen Liu ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Discrete Fourier Transform ◽  
Spectrum Analysis ◽  
Spectral Leakage ◽  
Overlapping Data

Discrete Fourier Transform (DFT) is widely used in spectrum analysis. All Phase Fast Fourier Transform (APFFT) is proposed to improve FFT. It has merits such as phase invariance and small spectral leakage. But APFFT is a concrete algorithm. There are no parameters to adjust the result. The paper researches APFFT by changing the length of the overlapping data segments of APFFT. This change gives APFFT some new characteristic and some meaningful results are got.

scholarly journals Background noise estimation of geomagnetic signal

2018 ◽  
Author(s):  
Xiuyi Yao ◽  
Suqin Zhang ◽  
Yuntian Teng ◽  
Dongmei Yang
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Diurnal Variation ◽  
Spectrum Analysis ◽  
Geomagnetic Field ◽  
Background Noise ◽  
Residual Error ◽  
Polynomial Degree ◽  
Geomagnetic Data ◽  
Main Component

Abstract. A fast Fourier transform was applied to fit the geomagnetic diurnal variation. Fitting results showed that when the polynomial degree was greater than 160, the residual error was close to 0 nT. White noise is the main component of the residual error when the polynomial degree was greater than 160, so this method was adopted to calculate the background noise of the geomagnetic field. Spectrum analysis further demonstrated the necessity to remove background noise from geomagnetic data.

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