共查询到20条相似文献，搜索用时 62 毫秒
1.
Hong-Guang Ma Xiao-Fei Zhu Jian-Feng Xu Ming-Shun Ai 《Journal of The Franklin Institute》2008,345(1):75-86
A new testing method for analog circuit is proposed in this paper. A low-pass Butterworth filter is taken as the typical system under test (SUT) since the analog circuits in different types of electronic systems can be regarded as the low-, band- or high-pass active (passive) filters. The chaotic signal, which is generated by an improved Chua's circuit, is employed as the excitation signal of SUT. The SUT is a “narrowband” system compared with the bandwidth of input signal, whose state is analyzed with an error-tracking approach. The experimental result depicts that this testing method can efficiently detect the change of the circuit parameter. Besides, another eight features are extracted from the output signal of SUT for analyzing the SUT states. A discussion is made for comparing the effectiveness of each feature according to the testing results. 相似文献
2.
In this study, a novel nonautonomous version of autonomous Chua's circuit is presented. The proposed nonautonomous version of Chua's circuit was designed by placing a sinusoidal source to the inner structure of the nonlinear resistor, namely, Chua's diode. The circuit's chaotic dynamics have been investigated by PSpice simulations and laboratory experiments. 相似文献
3.
In this paper, we study the existence of strange attractors in a switch-controlled Chua's circuit. This circuit is obtained from the original Chua's circuit by adding externally controlled switches to it in such a way to modulate the system state variables. This investigation is conducted from the perspective of a recent chaos theory of rank one maps. The externally controlled switches are used for the purposes of realizing the general settings of the theory. Both synchronous and asynchronous switch control schemes providing periodic kicks in various directions are investigated, and their effects on the resulting chaotic attractors are discussed. The results of the numerical simulations presented are in close agreement with the expectations of the theory. 相似文献
4.
The chaos characteristics of melt index have been first explored, and the Hilbert–Huang transform method and time delay embedding method are applied to multiscale dynamic analysis on the time series of the melt index (MI) in the propylene polymerization industry. The research results show that the embedding delay is 2, the embedding dimension is 5, the correlation dimension D2 is 1.57, and the maximum Lyapunov exponent is 0.143 for the melt index series, which provide clear evidence of chaotic multiscale features in the propylene polymerization process. Three intrinsic mode functions (IMFs) are decomposed from the melt index time series; the presence of non-integer fractal correlation dimension and positive finite maximum Lyapunov exponent are found in some IMF components. The PP melt index series are divided into two chaotic signals, a determined signal and a random signal respectively, and its complexity is therefore reduced. Furthermore, the coupling of subscale structures of the propylene polymerization is explored with the dimension of interaction dynamics and a robust algorithm for detecting interdependence. It is found that IMF(2) is the main driver in the coupling system of IMF(1)and IMF(2). All these provide a guideline for studying propylene polymerization process with chaotic multiscale theory and may offer more candidate tools to model and control propylene polymerization system in the future. 相似文献
5.
Wentao Ma Xinyu Qiu Jiandong Duan Yingsong Li Badong Chen 《Journal of The Franklin Institute》2018,355(4):1596-1613
This work studies the problem of kernel adaptive filtering (KAF) for nonlinear signal processing under non-Gaussian noise environments. A new KAF algorithm, called kernel recursive generalized mixed norm (KRGMN), is derived by minimizing the generalized mixed norm (GMN) cost instead of the well-known mean square error (MSE). A single error norm such as lp error norm can be used as a cost function in KAF to deal with non-Gaussian noises but it may exhibit slow convergence speed and poor misadjustments in some situations. To improve the convergence performance, the GMN cost is formed as a convex mixture of lp and lq norms to increase the convergence rate and substantially reduce the steady-state errors. The proposed KRGMN algorithm can solve efficiently the problems such as nonlinear channel equalization and system identification in non-Gaussian noises. Simulation results confirm the desirable performance of the new algorithm. 相似文献
6.
《Journal of The Franklin Institute》2018,355(18):9072-9084
The computational complexity of the numerical simulation of fractional chaotic system and its synchronization control is O(N2) compared with O(N) for integer chaotic system, where N is step number and O is the computational complexity. In this paper, we propose optimizing methods to solve fractional chaotic systems, including equal-weight memory principle, improved equal-weight memory principle, chaotic combination and fractional chaotic precomputing operator. Numerical examples show that the combination of these algorithms can simulate fractional chaotic system and synchronize the fractional master and slave systems accurately. The presented algorithms for simulation and synchronization of fractional chaotic system are up to 1.82 and 1.75 times faster than the original implementation respectively. 相似文献
7.
《Journal of The Franklin Institute》2003,340(6-7):415-422
In this paper, modelling and simulation of Chua's chaotic oscillator, which exhibits rich chaotic behaviours, are presented by using the bond graph model. Up to now modelling of Chua's chaotic oscillator using bond graph model is not yet developed. The non-linear resistor in the circuit is modelled in this contribution by linear time-invariant components and ideal switches using piecewise linearization approach. The bond graph model of all the circuit including switches is then generated. Simulations are provided via the computer program called as BOMAS using the obtained bond graph model. Finally, Chua's circuit is verified experimentally. It is shown that all experimental and simulation results well agree with the chaotic behaviours of Chua's circuit. 相似文献
8.
本文主要以单片机STC89C516为核心,分别连接了防盗装置、火焰报警装置和煤气报警装置集成于一体的设计。电路由信号输入,按键、指示和报警,单片机基本电路,信号测试、远端通信四部分组成。本设计增加一种防盗电路,特别适用于家庭。 相似文献
9.
The performance of a Wideband Code Division Multiple Access (W-CDMA) system using Pseudo Noise (PN) codes and chaotic codes in the presence of a Weibull fading channel is studied in this paper. The W-CDMA system modeled using Gaussian Approximation is analyzed on a Weibull fading channel which fades the amplitude of the transmitted signal randomly according to the Weibull distribution. Closed-form expressions for Bit Error Rate (BER) are derived and expressed in terms of Meijer?s-G function. Performance measures in terms of BER are plotted versus Signal-to-Noise Ratio (SNR) for various values of fading severity, average fading power, and channel memory using PN and chaotic codes. Performance comparison between PN codes and chaotic codes are also analyzed. 相似文献
10.
根据一种时间数字转换器的结构和性能,提出了组成全数字锁相环重要模块——时间数字转换器的设计方法。首先,设计出TDC模块的电路构成;其次,采用千分尺算法对电路信号进行设计和较正;最后,通过PSPICE仿真环境对电路图的设计,测出TDC的精确度,测得在CMOS环境下时间延迟的线性趋势。实验结果表明,与已有的时间数字转换器相比,该千分尺算法应用于TDC模块的设计,可以使时间数字转换器的性能有较大提高。 相似文献
11.
To retrieve the information from the serious distorted received signal is the key challenge of communication signal processing. The chaotic baseband communication promises theoretically to eliminate the inter-symbol interference (ISI), however, it needs complicated calculation, if it is not impossible. In this paper, a genetic algorithm support vector machine (GA-SVM) based symbol detection method is proposed for chaotic baseband wireless communication system (CBWCS), by this way, treating the problem from a different viewpoint, the symbol decoding process is converted to be a binary classification through GA-SVM model. A trained GA-SVM model is used to decode the symbols directly at the receiver, so as to improve the bit error rate (BER) performance of the CBWCS and simplify the symbol detection process by removing the channel identification and the threshold calculation process as compared to that using the calculated threshold to decode symbol in the traditional methods. The simulation results show that the proposed method has better BER performance in both the static and time-varying wireless channels. The experimental results, based on the wireless open-access research platform, indicate that the BER of the proposed GA-SVM based symbol detection approach is superior to the other counterparts under a practical wireless multipath channel. 相似文献
12.
Chaotic waveforms are natural information carriers since a correspondence can be established between the symbolic dynamics of a chaotic oscillator and the symbols of a message. Message symbols can be efficiently encoded in a chaotic waveform by applying vanishingly small perturbations to an oscillator to guide its symbolic dynamics to follow a desired course. Recently, two chaotic hybrid dynamical systems were shown to have matched filters enabling robust reception of chaotic communication waveforms in the presence of noise. The first of these, the exact shift oscillator, produces waveforms with desirable properties similar to antipodal signaling, but a physical implementation may be difficult to control using small perturbations. The second oscillator, the exact folded-band oscillator, produces less optimal waveforms but is more easily controlled. Here we introduce a method for generating waveforms of the exact shift oscillator by summing waveforms from a bank of easily controlled exact folded-band oscillators. We show that any solution of the exact shift oscillator can be so constructed using only three folded-band oscillators. Thus, this scheme allows us to realize the advantages of both chaotic systems while overcoming their individual disadvantages, thereby enabling practical chaos communications. 相似文献
13.
Giuseppe Grassi Author Vitae 《Journal of The Franklin Institute》2010,347(2):438-451
Projective synchronization is a type of chaos synchronization where the response system states are scaled replicas of the drive system states. This paper deals with the propagation of projective synchronization in a series connection of N chaotic discrete-time drive systems and N response systems. By exploiting an observer-based approach, the paper demonstrates that dead-beat projective synchronization (i.e., exact synchronization in finite time for any scaling factor) is achieved between the nth drive and nth response systems. In particular, it is shown that projective synchronization starts from the innermost (Nth) drive-response system pair and propagates toward the outermost (first) drive-response system pair. Only a single scalar synchronizing signal connects the cascaded drive and response systems. Finally, an example illustrates the propagation of different types of chaos synchronization in a series connection consisting of a Gingerbreadman map, a third order hyperchaotic Henon map and a Lozi map. 相似文献
14.
《Journal of The Franklin Institute》2018,355(18):9245-9270
This paper deals with noise detection and threshold free on-line denoising procedure for discrete scanning probe microscopy (SPM) surface images using wavelets. In this sense, the proposed denoising procedure works without thresholds for the localisation of noise, as well for the stop criterium of the algorithm. In particular, a proposition which states a constructive structural property of the wavelets tree with respect to a defined seminorm has been proven for a special technical case. Using orthogonal wavelets, it is possible to obtain an efficient localisation of noise and as a consequence a denoising of the measured signal. An on-line denoising algorithm, which is based upon the discrete wavelet transform (DWT), is proposed to detect unavoidable measured noise in the acquired data. With the help of a seminorm the noise of a signal is defined as an incoherent part of a measured signal and it is possible to rearrange the wavelet basis which can illuminate the differences between its coherent and incoherent part. In effect, the procedure looks for the subspaces consisting of wavelet packets characterised either by small or opposing components in the wavelet domain. Taking real measurements the effectiveness of the proposed denoising algorithm is validated and compared with Gaussian FIR- and Median filter. The proposed method was built using the free wavelet toolboxes from the WaveLab 850 library of the Stanford University (USA). 相似文献
15.
利用导线、电阻和分布电容组成信号衰减电路,模拟采集器现场运行环境下信号衰减变化,对现场有抄收故障的采集器与未使用的新采集器作对比测试,结果表明:信号强、抗干扰的能力大,信息指令在转送过程中丢失少,信号强度与抄见率呈极显着相关。返回的采集器与新采集器的抄见率无明显的区别。线路对信号的衰减不是主要原因,要检测运用场地电能质量、噪音和信号强度等,分析现场的信号故障原因。 相似文献
16.
A complete theory of diffusion of absorbing gases in porous solids is developed. Both ordinary and thermal diffusion are considered. The thermodynamics of irreversible processes is used to derive the general flux equations.A new theoretical model of surface diffusion is presented. Moreover, the proper method of combining surface and gas-phase fluxes is established. The total flux in the pores is represented by a 5 parameter model, which includes the effects of (1) free (gaseous) diffusion, (2) Knudsen diffusion, and (3) surface diffusion.The design of a new diffusion cell is presented along with a stagewise method for analyzing results. The cell is unique in that specimens mounted in copper clad circuit board material permits nonisothermal as well as isothermal operation. Earlier designs were confined to isothermal operation due to mounting specimens in metallic materials such as brass and aluminum. 相似文献
17.
W.B. Nottingham 《Journal of The Franklin Institute》1931,211(3):271-301
The principle of the grid-controlled arc or thyratron is briefly described and the norminal ratings as regards filament current, maximum plate current etc. of four important thyratrns are given in table form. Methods of measuring the grid current, critical grid potential, etc., with D.C. power supply are given along with the results obtained on the General Electric Company thyratrons FG-17, FG-27 and FG-67. Characteristics obtained with A.C. power supply are also shown for these thyratrons and some of the relative advantages of the “phase-shift” and the “critical potential” methods of control are discussed when used in connection with photoelectric cell circuits. The A.C. measurements seem to show that a time of 10?3 second is required to start a thyratron. An amplifier circuit is shown by which it is theoretically possible to control a thyratron circuit using an input current to the amplifier of 10?11 ampere. 相似文献
18.
In this paper, a constrained regularized least square (RLS) state estimator is developed for deterministic discrete-time nonlinear dynamical systems subject to a set of equality and/or inequality constraints. The stability of the estimation error is rigorously analyzed. The proposed estimator is then used to handle the important problem of secure communication. At the transmitting end, the output of the constrained unified chaotic system is used as a chaotic mask to achieve a satisfactory and typical secure communication scheme. The encrypted data signal is injected into the transmitter and simultaneously transmitted to the receiver through a public channel. At the receiving end, the constrained RLS estimator is used to reconstruct the states of the constrained unified chaotic system. Simulation results are presented to show the impact of the imposed constraints on the waveform and the pattern of the generated chaotic signal as well as the ability of the proposed estimator to synchronize the actual and estimated states of the constrained unified chaotic system. Moreover, the proposed estimator is applied to recover discrete signals such as digital images where computer simulation results are provided to show the effectiveness of the proposed estimation scheme. 相似文献
19.
The Cepstrum processing method has been used on power cables (1, 2) for determining regions of damage. The method consists of: (1) observing the spectrum of an original broad band signal source, (2) introducing the signal into the cable, (3) computing the change in the observed spectrum (as a result of echos from regions of cable non-uniformity) when the signal is injected into the cable, and finally (4) computing the power-spectrum of the change in observed spectrum. A limitation of this technique is the use of band-limiting spectrum analyzers. Their limited bandwidth reduces range resolution estimation when used with the Fast Fourier Transform (FFT) technique. The maximum entropy method (MEM) is a more useful spectral estimator for this measurement technique. Examples are presented which show a comparison of the FFT and MEM techniques applied to practical cables. 相似文献