Advanced Materials Research Vols. 538-541

Abstract: Abstract. The free vibration of the piezoelectric laminated cylindrical shell with throughout circumference delamination is analyzed in this paper. By introducing the Heaviside step function into assumed displacement components and using elastic piezoelectric theory, the constitutive relations of the piezoelectric laminated shell with delamination are established. Then the dynamic governing equations of the structure are derived through variational principle. In numerical examples, the effects of delamination length, depth, boundary condition, material property and thickness of piezoelectric layer on the first natural frequency of piezoelectric laminated shell with delamination are investigated.

Abstract: An over-damped second-order linear system with fluctuant coefficient of the second-order derivative and signal-modulated noise is considered. Based on linear-system theory, the expression of the output amplitude is obtained. Analytical results shows that the output amplitude is a non-monotonic function of the noise strength, and it varies non-monotonously with the increase of the system parameter a and b, while it decreases monotonously with the increase of the signal frequency and the system parameter c.

Abstract: This paper presents a parallel implementation process for the structural dynamic topology optimization problem. An energy flow analysis based topology optimization model is established for the objective of vibration control. The structural vibrations are excited by time-harmonic external mechanical loading with prescribed frequency and amplitude. Design variables are parameterized using Bi-material Solid Isotropic Material with Penalization (SIMP) models and Method of Moving Asymptotes (MMA) is applied for variable updating. A Parallel Finite Element (PFE) model is constructed by re-group the original finite element model. Each PFE will be computed by different processor, and then assembles together to get the global response. The efficiency and stability can be improved, which has been illustrated in the results discussion section in the end of the paper.

Abstract: The artificial fish swarm algorithm, it may be trapped in local optimum in the later evolution period and its search accuracy is dependent on step length which is hard to keep balance between rapidity and accuracy. Aimed at the defects of AFSA, a novel global artificial fish swarm algorithm is proposed in this paper, in which normal chaotic search on earlier stage is modified , and a differential evolution with improved chaos search was proposed to lead artificial fish into global optimum value. The experimental results show that the proposed algorithm is not only superior to traditional one but also can make the result greater.

Abstract: The phenomenon of stochastic resonance (SR) in a time-delayed bistable system with square-wave signal, a constant force, with asymmetric dichotomous noise and multiplicative and additive colored noise is investigated. It is found that, the SR behavior can be observed on the signal-to-noise ratio (SNR) curves as a function of the intensity and asymmetry of the dichotomous noise, as a function of the amplitude of the square-wave, the constant force, as well as of the strength of the colored noises.

Abstract: Puts forward a Gain Adjustable Fast Intelligent Tracking (GAFIT) algorithm, and realize quick and accurate location of the goal, when the detection signal is weaker. According to the size, location and output signal of the goal in four quadrant detector, the linear probe interval is determined in the four quadrant detector. On this interval, a liner relation can be get between the spot position and the corresponding output signal. The target quick location is realized with this relation. On the other hand, the sum signal of the four quadrant detector is sampled in real-time, this sum is related to the sensor’s signal strength, then the change rate of the signal strength can be get, using adaptive learning ways to get the change trend of signal strength, and realized dynamic adjustment of the signal gain, in order to improve the signal resolution ratio when signal is weak, the tracking accuracy can be improved with this way. The experimental data show that GAIFT algorithm can rapidly locate position in the linear interval and accurately track through the dynamic change signal gain for the weaker signal. tracking precision can be improved to 0.018 degrees

Abstract: Object tracking is to search the most similar parts to targets in video sequences. Among the various tracking algorithms, mean shift tracking algorithm has become popular due to its simplicity, efficiency and good performance. This paper focused on mean shift tracking algorithm, which is a modeling mechanism based on statistical probability density function. In practice, when the background of the tracking and characteristics of the target are similar, pixels of background occupy a large proportion in the histogram. The traditional mean shift cannot adapt to the mutative scene. Meanwhile, if there is block or disappearance, the result is not exact. Three algorithms were given for above difficulties. A weighted template background was established, that can highlight the features of target and improve real-time. Then this paper presented a selective mechanism to update the target model. Every component is updated based on the contribution to the target model. Finally, the Kalman filter was combined with mean shift algorithm. We saw the prediction points of Kalman filter as the initial point, carried out the mean shift iteration and then updated Kalman filter using the ultimate location. Extensive experimental results illustrated excellent agreement with these methods.

Abstract: Numerical method is extensively used to determine the workspace of a robotic manipulator. However, four or more degree manipulator mathematic models are too computationally intensive to be finished by computer. In this paper , a fast algorithm for workspace of a robotic manipulator is introduced. The method is based upon the singularity analysis of serial manipulator so that the computation amount is greatly reduced. The practical example of 6R manipulator is treated with this method. Its workspace is drawn and determined.

Abstract: The lemniscate type crane is fabricated by Kenz-Figee B.V. of the Netherlands. There are great differences in outward appearance, geometric shape, luffing performance between lemniscate type crane and ordinary double-link type crane. Lemniscate type crane has some advantages, i.e. lower centre of weight, practical and reasonable structure, strongly anti-wind and easy operation. Based on inverse design and principle of mechanics, force analysis and luffing moment of luffing mechanism of lemniscate type crane is researched and solved.

Abstract: A redundant lifting wavelet packet analysis based on variable parameter was presented, which was used to extract the weak fault features of bearing submerged in background noise. Through different choices of parameters in the design formula of predictor based on least square method of fitting, six asymmetric wavelets with various characteristics were constructed, which were then respectively used for redundant lifting wavelet packet decomposition to signal layer by layer. All the results obtained by decomposition were adopted to establish the objective function of minimum norm, through which the optimal wavelet that best matches the feature information is selected for each node signal. The node signals got by last decomposition were utilized for wavelet packet energy analysis, while the node signal with maximum energy was chosen for single branch reconstruction and envelop spectrum analysis. The proposed method above is applied to process the engineering data of bearing with fault and good results are gained by which the effectiveness of this method is well validated.