Synchronization of Different Fractional Order Time-Delay Chaotic Systems Using Active Control

Chaos synchronization of different fractional order time-delay chaotic systems is considered. Based on the Laplace transform theory, the conditions for achieving synchronization of different fractional order time-delay chaotic systems are analyzed by use of active control technique. Then numerical simulations are provided to verify the effectiveness and feasibility of the developed method. At last, effects of the fraction order and the time delay on synchronization are further researched

Synchronization in a Novel Local-World Dynamical Network Model

Advances in complex network research have recently stimulated increasing interests in understanding the relationship between the topology and dynamics of complex networks. In the paper, we study the synchronizability of a class of local-world dynamical networks. Then, we have proposed a local-world synchronization-optimal growth topology model. Compared with the local-world evolving network model, it exhibits a stronger synchronizability. We also investigate the robustness of the synchronizability with respect to random failures and the fragility of the synchronizability with specific removal of nodes

Study on Location Algorithms of Beamforming based on MVDR

Acoustic emission is an effective method of locating the rubbing fault. In order to solve the problem that satisfactory location accuracy is difficult to obtain because of the waveform distortion caused by signal propagation during the application of time delay estimation method in acoustic emission position estimation, beam-forming technique is applied to acoustic emission source location. Simulation studies have been made on the performance of near-field time-domain and frequency domain beam-forming in the location of rubbing acoustic emission source. The paper adopts the wideband signal minimum variance distortionless response (MVDR) location estimation method based on sub-band decomposition to avoid the problems of poor noise immunity and low resolution of traditional beam-forming. Decompose each group of array signals into a number of sub-band of equal length, conduct Fourier transformation on each sub-band to calculate the covariance matrix of each frequency component, get the two-dimensional joint distribution function of the MVDR output power of each sub-band with respect to the distance and azimuth angle, then synthesize the MVDR power of wideband signal, obtain the azimuth spectrum estimation of all frequency bands, and finally get the location of the acoustic source by the peak point. The experimental results show that this algorithm can accurately identify the rubbing fault location

Localization of Acoustic Emission Source Based on Chaotic Neural Networks

Because of containing several model waveforms and transmission speed of each model are various, the source signal of rub-impact acoustic emission (AE) will lead to waveform distortion in propagation process, and it is difficult to achieve exact source location by traditional time difference of arrival algorithm. A chaotic neural network technique was introduced to calculate the location of AE source. Numerous researches show that rotor rub-impact fault has sufficient non-linear features, so obtain the characteristics of the non-linear dynamics which reveal the AE source form the rub-impact data by using the chaos theory and use it as the input of the neural network to get the localization. We propose a modified Gaussian Mixed Model (GMM) with an embedded Time Delay Neural Network (TDNN). It integrates the merits of GMM and TDNN. Simulation results prove, theoretically and practically, that it can locate AE source efficiently and provide the basis for the rotor rub-impact fault diagnosis, so it has good application prospect and is worth to research further more

Effect of Deformation Temperature on Mechanical Properties and Deformation Mechanisms of Cold-Rolled Low C High Mn TRIP/TWIP Steel

The microstructure and mechanical properties of cold-rolled Fe-18Mn-3Al-3Si-0.03C transformation induced plasticity/twinning induced plasticity (TRIP/TWIP) steel in the temperature range of 25 to 600 °C were studied. The experimental steel exhibited a good combination of ultimate tensile strength (UTS) of 905 MPa and total elongation (TEL) of 55% at room temperature. With the increase of deformation temperature from 25 to 600 °C, the stacking fault energy (SFE) of the experimental steel increased from 14.5 to 98.8 mJm−2. The deformation mechanism of the experimental steel is controlled by both the strain induced martensite formation and strain induced deformation twinning at 25 °C. With the increase of deformation temperature from 25 to 600 °C, TRIP and TWIP effect were inhibited, and dislocation glide gradually became the main deformation mechanism. The UTS decreased monotonously from 905 to 325 MPa and the TEL decreased (from 55 to 36%, 25–400 °C) and then increased (from 36 to 64%, 400–600 °C). The change in mechanical properties is related to the thermal softening effect, TRIP effect, TWIP effect, DSA, and dislocation slip

Superior Mechanical Properties and Work-Hardening Ability of Ultrafine-Grained Quenched and Partitioned Steels Processed by a Novel Approach Involving Asymmetric Hot Rolling

An approach is proposed to enhance the mechanical properties and work-hardening (WH) ability of low-alloy steels. Using asymmetric hot rolling (AHR) and subsequent direct quenching (DQ) prior to the quenching and partitioning (Q&P) process, an ultrafine-grained Q&P steel with excellent combination of tensile strength of ~1000 MPa and total elongation of ~35% was obtained, which exhibited high WH exponent at higher strain induced by the higher volume fraction and higher stability of film-like retained austenite located between the martensite laths