Applied Mechanics and Materials Vols. 182-183

Abstract: In this paper, we deal with the problem of the ship degaussing coils optimal calibration by a linearly decreasing weight particle swarm optimization (LDW-PSO). Taking the ship’s magnetic field and its gradient reduction into account, the problem is treated as a multi-objective optimization problem. First a set of scale factors are calculated by LDW-PSO to scale the two kinds of objective function, then the multi-objective optimization problem is transformed to a single objective optimization problem via a set of proper weights, and the problem is solved by LDW-PSO finally. A typical ship degaussing system is applied to test the method’s validity, and the results are good.

Abstract: Aim at search precocity of particle swarm algorithm and slow convergence speed problem for ant colony algorithm, in the automatic guided vehicle path optimization a path optimization algorithm is proposed, which is fused by particle swarm algorithm and ant colony algorithm. Firstly, robot motion space model of the algorithm is created using link figure. After got fixed circulation rapid global, search to get more optimal path by means of improved fastest convergence ant system, then using a particle ants information communication method to update pheromone, finally, optimal path is drew. The simulation experiment shows that, even in the complex environment, this algorithm can also has the advantage of ant colony algorithm to optimize the result accurately and particle swarm algorithm local optimization accurately and rapidly, and a global security obstacle avoidance of optimal path is plot, the route is shorten 8% compare than the general ant colony algorithm.

Abstract: In the system of terrain following, after planning the optimal reference path, the key problem is the design of advanced path tracking system, there were many optimal path tracking schemes presented previously, but , they have the common characteristics of complicated arithmetic and tremendous calculating quantity, so, in the paper, for the sake of attaining simple and precise controller, adopting output predictive control to calculate control instructions and applying fuzzy inference to compensate the controlled quantity make fighter track the planned optimal reference path automatically, plenty of numeral simulation referring to various typical terrains shows that the scheme is feasible.

Abstract: With the recent technological advances in zigbee, 3G and embedded technology, development of home automation has been enabled and become dramatically feasible. Based on the advantage and feature of Zigbee and 3G, this paper introduces a home automation system. First of all, this paper discuss the network topology of system, which makes up of inner-net, home gateway and outer-net. The inner-net, consisting of subsystem, security alarm subsystem and smart appliance control subsystem, communicates with outer-net by home gateway. And then, this paper mainly analyzes hardware and software design of these subsystems and gateway and it gives an implement scheme. At last, the paper proposes a solution of low power strategy.

Abstract: With wind farm capacity continuously increasing, remarkable characteristics of wind power make nonlinear dynamic characteristics of wind power system more apparent than conventional power system. Domestic and international experience shows that the voltage instability is main forms of wind power system instability. The bifurcation theory is one of the most powerful tools in analysis of structure stability of nonlinear dynamic system. Therefore application of bifurcation theory not only reveals the voltage stability mechanism, but also has important theoretic value and practical value for the security analysis of the whole power system, especially for voltage stability of wind power system.

Abstract: Function fhan() and tracking differentiator are important components of Active Disturbance Rejection Control Technique. It is pointed out that function fhan() is not the optimal control synthesis function of discrete system, but function fsun() is. Amplitude and phase frequency characteristic curves of tracking differentiators constructed respectively by function fhan() and fsun() are given by computer simulations. The account formula about turning frequency is also given. Influence of parameter variation on tracking differentiator frequency characteristic is analyszed. The conclusion of this paper is supplement and perfection for the theory of tracking differentiator in Active Disturbance Rejection Control Technique, and it can promote rapid development of Active Disturbance Rejection Control Technique.

Abstract: The strain at the low-velocity impact proceeding was monitored by the fiber Bragg grating (FBG) sensors embedded in the triangle area of the T-stiffened panels. The results show that the strain in whole impact process can be monitored by FBG sensors. Furthermore, the max-strain measured by FBG sensors changed sensitively depending on the different impact energy. It can be hoped that the FBG sensors can be used as online-monitoring technique to improving the safety of the composite structures.

Abstract: The vibration signals of the running machine contain non-stationary components. Usually, these non-stationary components contain abundant information on machine faults. In this paper, the Hilbert–Huang transform (HHT) method for the machine fault diagnosis is proposed. The empirical mode decomposition (EMD) method and Hilbert transform are key parts of the Hilbert–Huang transform method. The EMD will generate a collection of intrinsic mode functions (IMF). By applying EMD method and Hilbert transform to the vibration signal, we can get the Hilbert spectrum from which the faults in a running machine can be diagnosed and fault patterns can be identified. The practical vibration signals measured from roller machine with eccentric and friction faults are analysed by the Hilbert–Huang transform and Fourier transform in this paper. Finally, HHT’s performance in rolling machine fault detection is compared with that of the Fourier transform. The comparison results have shown that the HHT is superior than the Fourier transform in machine fault diagnostics. The different failure characteristic frequencies can be distinguished in the component of different orders of IMF, and the time and frequency of failure characteristic frequency appearance can be clearly reflected in the Hilbert spectrum.

Abstract: In this paper, the space time-index plots were introduced and used to determine the nonstationarity of the fault diagnosis in order to handle faults in the nonstationary stage. By using the decomposition and reconstruction of wavelet transform for nonstationary signal, the author targeted on the bandwidth and select information with pertinence, and then analysed the reconstruct signal spectrum for extracting the typical character of fault. The results show that the space time-index method is applicable to judge the nonstationary and the wavelet transform method in fault diagnosis is effective for the nonstationary signal.

Abstract: The 3D finite element simulation of three-roller cold rolling model for stainless steel tube was established using finite element software MSC. Marc. The metal flow rule of contact deformation zone, the distributions of equivalent stress and strain were analyzed. The experiment of cold rolling process was carried out based on the technical parameters of the simulation.