scholarly journals An Improved Chaotic Detection System for Metal Detectors

2021 ◽  
Vol 2087 (1) ◽  
pp. 012065
Author(s):  
Wenjing Hu
Keyword(s):  
Detection System ◽  
Duffing Oscillator ◽  
Threshold Value ◽  
Matlab Simulation ◽  
Metal Detector ◽  
Duffing System ◽  
Characteristic Exponents ◽  
Lyapunov Characteristic Exponents ◽  
Simulation Results ◽  
Metal Detectors

Abstract This paper first applies a chaotic system-Duffing oscillator to a metal detector, and uses RHR algorithm to compute two Lyapunov characteristics exponents of the Duffing system. In this way, the two Lyapunov characteristic exponents can help to judge the Duffing system being chaotic or not quantitatively. And also help to get the threshold value more accurately. Then a simulation model of Duffing system fit for detectors is established by Matlab. Simulation results indicate that an suitable Duffing system can improve the sensitivity of a detector effectively.

Quantitative Analysis of Noise Impact on Duffing Chaotic Detection System Using Lyapunov Characteristic Exponents

2011 ◽  
Vol 130-134 ◽  
pp. 1331-1337
Author(s):  
Wen Jing Hu ◽  
Zhi Zhen Liu ◽  
Zhi Hui Li
Keyword(s):  
Detection System ◽  
Signal To Noise Ratio ◽  
Duffing Oscillator ◽  
Threshold Value ◽  
System State ◽  
Signal To Noise ◽  
Phase Trajectories ◽  
Lyapunov Characteristic Exponents ◽  
Noise Ratio ◽  
System States

Performance of the Duffing oscillator to detect weak signals buried in heavy noise is analyzed quantitatively by LCEs. First in the case of noise, differential equations to compute LCE s are derived using RHR algorithm, so the quantitative criteria to identify system states are obtained. Then using LCEs, the threshold value of the forced periodic term is found accurately. Finally the system state and state change are analyzed using LCEs by keeping the threshold value and varying the noise intensity, and the minimum signal to noise ratio is determined. By contrast of phase trajectories and LCEs, it shows that phase trajectories disturbed by strong noise sometimes are ambiguous to our eyes, but through LCEs, the system state can be identified clearly and quantitatively especially in strong noise background. So the minimum signal to noise ratio can be obtained accurately.

Weak photoacoustic signal detection based on the differential duffing oscillator

2018 ◽  
Vol 32 (09) ◽  
pp. 1850103 ◽  
Author(s):  
Chenjing Li ◽  
Xuemei Xu ◽  
Yipeng Ding ◽  
Linzi Yin ◽  
Beibei Dou
Keyword(s):  
Signal Detection ◽  
Photoacoustic Spectroscopy ◽  
Detection System ◽  
Signal To Noise Ratio ◽  
Duffing Oscillator ◽  
Threshold Value ◽  
Photoacoustic Signal ◽  
Weak Signal ◽  
Weak Signal Detection ◽  
First Time

In view of photoacoustic spectroscopy theory, the relationship between weak photoacoustic signal and gas concentration is described. The studies, on the principle of Duffing oscillator for identifying state transition as well as determining the threshold value, have proven the feasibility of applying the Duffing oscillator in weak signal detection. An improved differential Duffing oscillator is proposed to identify weak signals with any frequency and ameliorate the signal-to-noise ratio. The analytical methods and numerical experiments of the novel model are introduced in detail to confirm its superiority. Then the signal detection system of weak photoacoustic based on differential Duffing oscillator is constructed, it is the first time that the weak signal detection method with differential Duffing oscillator is applied triumphantly in photoacoustic spectroscopy gas monitoring technology.

scholarly journals Threshold for Chaos of a Duffing Oscillator with Fractional-Order Derivative

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Wuce Xing ◽  
Enli Chen ◽  
Yujian Chang ◽  
Meiqi Wang
Keyword(s):  
Numerical Simulation ◽  
Fractional Order ◽  
Chaotic Motion ◽  
Duffing Oscillator ◽  
Threshold Value ◽  
Order Derivative ◽  
Necessary Condition ◽  
Threshold Curve ◽  
Fractional Order Derivative ◽  
Simulation Results

In this paper, the necessary condition for the chaotic motion of a Duffing oscillator with the fractional-order derivative under harmonic excitation is investigated. The necessary condition for the chaos in the sense of Smale horseshoes is established based on the Melnikov method, and then the chaotic threshold curve is obtained. The largest Lyapunov exponents are provided, and some other typical numerical simulation results, including the time histories, frequency spectrograms, phase portraits, and Poincare maps, are presented and compared. From the analysis of the numerical simulation results, it could be found that, near the chaotic threshold curve, the system generates chaos via the period-doubling bifurcation, from single periodic motion to period-2 motion and period-4 motion to chaotic motion. The effects of fractional-order parameters, the stiffness coefficient, and the damping coefficient on the threshold value of the chaotic motion are analytically discussed. The results show that the coefficient of the fractional-order derivative has great effect on the threshold value of the chaotic motion, while the order of the fractional-order derivative has less. The analysis results reveal some new phenomena, and it could be useful for designing or controlling dynamic systems with the fractional-order derivative.

Computation of Lyapunov Characteristic Exponents Using Parallel Computing

2017 ◽  
Author(s):  
Hubertus F. von Bremen ◽  
Michael J. Bonilla
Keyword(s):  
Dynamical System ◽  
Parallel Implementation ◽  
Symmetric Matrix ◽  
Computer Memory ◽  
Characteristic Exponents ◽  
Lyapunov Characteristic Exponents ◽  
Computationally Expensive ◽  
Simulation Results ◽  
Arbitrary Dimensions ◽  
Derivatives Of

In [1] a method to accurately compute the Lyapunov Characteristic Exponents of continuous dynamical systems of arbitrary dimensions was presented. However, it can be computationally expensive, because it requires the computation of the time derivatives of the entries of the exponential of a skew-symmetric matrix. In this paper, we present an implementation of the method in [1] that takes advantage of the fact that some of the computations can be done in parallel. The speedup in the computations depends on the number of CPU cores used and the computer memory. Numerical simulations show improvements in efficiency when using the parallel implementation. Our implementation retains the accuracy of the method in [1] with the added advantage of a speedup in computations. Numerical simulation results are presented for a dynamical system of dimension seven and one of dimension forty-nine.

Design and Implementation of Shift Frequency Measurement System for Metal Detector

2014 ◽  
Vol 695 ◽  
pp. 844-849
Author(s):  
Yin Thu Win ◽  
Aung Lwin Moe ◽  
Aung Ko Ko Thet
Keyword(s):  
Measurement System ◽  
High Performance ◽  
Detection System ◽  
Cost Effective ◽  
Frequency Measurement ◽  
Metal Detector ◽  
Design And Implementation ◽  
Metal Detection ◽  
Metal Detectors ◽  
Shift Frequency

Metal detectors are widely used to find embedded metal within objects which are beyond eye site. This study concerns the design and implementation of frequency counter with 4 digits seven segment LED display for metal detection system using PIC microcontroller. New algorithm for frequency counting is developed. The software is also developed to detect the shift frequency measurement from the VCO output. The corresponding frequency at the VCO output of Induction Balance Metal detector is clarified. The experimental results of this research revealed that using PIC16F628A for frequency measurement system is able to provide very high accuracy for metal detection application. Additionally, the proposed system is the cost effective, less circuitry, high performance control system and feasible for many other metal detection applications.

Simulation and Analysis of Dynamic Characteristics of Rolling Motion of Rotational Molding Ship

2014 ◽  
Vol 556-562 ◽  
pp. 1278-1281
Author(s):  
Qi Guo Yao ◽  
Yu Liang Liu
Keyword(s):  
Parametric Resonance ◽  
Factorization Method ◽  
Operating Conditions ◽  
Qr Factorization ◽  
Rolling Motion ◽  
Rotational Molding ◽  
Longitudinal Waves ◽  
Characteristic Exponents ◽  
Lyapunov Characteristic Exponents ◽  
Simulation Results

Parametric resonance can lead to roll motions and endanger the ship, cargo and crew. The QR-factorization method for calculating lyapunov characteristic exponents (LCEs) was introduced. And then, parametric resonance stability of ships in longitudinal waves was analyzed by taking the fishing-entertainment rotational molding boat as an example. Simulation results show that, this method can be used to analyze ship stability and to accurately identify safe and unsafe operating conditions for a ship in longitudinal waves.

Prediction of Solutions of the Duffing System with Tuned Mass Damper

2020 ◽  
Vol 22 (4) ◽  
pp. 983-990
Author(s):  
Konrad Mnich
Keyword(s):  
Dynamical System ◽  
Duffing Oscillator ◽  
Probabilistic Approach ◽  
Nonlinear Dynamical System ◽  
Tuned Mass Damper ◽  
Nonlinear Dynamical ◽  
Duffing System ◽  
Mass Damper ◽  
Basin Stability ◽  
Stability Concept

AbstractIn this work we analyze the behavior of a nonlinear dynamical system using a probabilistic approach. We focus on the coexistence of solutions and we check how the changes in the parameters of excitation influence the dynamics of the system. For the demonstration we use the Duffing oscillator with the tuned mass absorber. We mention the numerous attractors present in such a system and describe how they were found with the method based on the basin stability concept.

MINIMIZING THE EFFECTIVE AREA OF SCATTERING BY MEANS OF CHANGING THE RELATIVE MAGNETIC PERMEABILITY

2021 ◽  
pp. 85-88
Author(s):  
А.В. Володько ◽  
С.М. Фёдоров ◽  
Е.А. Ищенко ◽  
М.А. Сиваш ◽  
Л.В. Сопина ◽  
...  
Keyword(s):  
Magnetic Permeability ◽  
Dielectric Material ◽  
Threshold Value ◽  
Effective Area ◽  
Large Object ◽  
Frequency Dependent ◽  
Relative Magnetic Permeability ◽  
Effective Scattering Area ◽  
Maximum Value ◽  
Simulation Results

Исследуется зависимость эффективной площади рассеяния (ЭПР) от относительной магнитной проницаемости материала, из которого изготавливается структура. В качестве тела моделирования был выбран шар, который изготовлен из диэлектрического материала, у которого возможно выполнять изменение относительной магнитной проницаемости. По полученным результатам моделирования построены графики зависимости максимального значения моностатической ЭПР от частоты, а также от относительной магнитной проницаемости среды. Было показано, что с увеличением относительной магнитной проницаемости материала изготовления происходит увеличение значения ЭПР объекта, а также обнаружена зависимость эффективной площади рассеяния от соотношения размеров шара и длиной волны, так при превышении порогового значения, после которого шар становится крупным объектом, ЭПР резко возрастает. По результатам исследования был построен график зависимости эффективной площади рассеяния шара от относительной магнитной проницаемости материала изготовления. Доказана возможность применения материала с частотозависимой относительной магнитной проницаемостью в качестве стелс-покрытия. В статье содержится исследуемая модель, графики полученных результатов, по которым можно легко определить зависимость ЭПР от частоты и от относительной магнитной проницаемости материала изготовления The article investigates the dependence of the effective scattering area (ESA) on the relative magnetic permeability of the material from which the structure is made. We chose a sphere as the modeling body, which is made of a dielectric material, in which it is possible to change the relative magnetic permeability. Based on the obtained simulation results, graphs of the dependence of the maximum value of monostatic ESA on frequency, as well as on the relative magnetic permeability of the medium, were constructed. It was shown that with an increase in the relative magnetic permeability of the material of manufacture, an increase in the value of the ESA of the object occurs, and the dependence of the effective scattering area on the ratio of the size of the ball and the wavelength was found, so when the threshold value is exceeded, after which the ball becomes a large object, ESA rises sharply. Based on the results of the study, a graph of the dependence of the effective scattering area of the sphere on the relative magnetic permeability of the material of manufacture was built. The possibility of using a material with a frequency-dependent relative magnetic permeability as a stealth coating was proven. The article contains the investigated model, graphs of the results obtained, by which it is easy to determine the dependence of the ESA on the frequency and on the relative magnetic permeability of the material of manufacture

scholarly journals Ultrasound detection using optical interferometry

2021 ◽  
Author(s):  
Nusrat Jahan Surovy
Keyword(s):  
Thin Film ◽  
Ultrasound Imaging ◽  
Detection System ◽  
Incidence Angle ◽  
Low Cost ◽  
3D Ultrasound ◽  
Attractive Alternative ◽  
Simulation Results ◽  
Exerted Pressure ◽  
Piezoelectric Devices

Ultrasound imaging is a widely used noninvasive imaging technique for biomedical and other applications. Piezoelectric devices are commonly used for the generation and detection of ultrasound in these applications. However, implementation of two-dimensional arrays of piezoelectric transducers for 3D ultrasound imaging is complex and expensive. Optical Fabry-Perot interferometry is an attractive alternative to the piezoelectric devices for detection of ultrasound. In this method a thin film etalon is constructed and used. Light reflected from the two surfaces of this thin film produces an intensity which depends on the film thickness. When ultrasound is incident on the film, it changes the thickness of the film and consequently modulates the light intensity on the film. In our work, we made two types of etalon (Finesse 2) for our experiment. We detected lower frequency ultrasound (0.5 MHz or 1 MHz) using the build etalon. We determined a linear relationship between the strength of the optical signals and the exerted pressure on a film by the ultrasound. The dependence of the etalon performance on the light wavelength was demonstrated indirectly by measuring the signal at various light incidence angle. Simulation results are also presented. Lastly, we proposed the optimum design of this detection system based on the simulation results. This method of ultrasound detection can be a potential low-cost approach for 3D ultrasound imaging.

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