Advanced Materials Research Vols. 466-467

Abstract: In order to diagnose and exempt the fault of aircraft electrical system accurately and fast, on the basis of analyzing the lost mode and fault mechanism of certain aircraft electrical system, fault structure are built and structure are built and fault models are analyzed by adopting the analytical technology based on regular fault structure. Two induction mechanisms, namely directional and anti-directional inference are introduced and the component methods are studied based on the knowledge corpus of data corpus technique. The result shows the inference results of fault diagnosis system are in accordance to reality and improve the intelligentized level of fault diagnosis system for aircraft electrical power.

Abstract: Aiming at the invisibility of the electromagnetic environment (EME), this paper presents the method to visualize the weapon equipments EME. The visualization can be divided into two steps. Firstly, we can model the weapon equipments EME to get the electromagnetic data by the finite difference time domain(FDTD) and the transformation from the near field to the far field. Secondly, we can render the electromagnetic data by the data field visualization. The experiment shows that this way is feasible and effective.

Abstract: Aiming at the difficulty in crack detecting for bridges, a wireless crack detecting system based on machine vision and RC model helicopter was designed and realized. This system used a wireless camera to capture the surface images of bridges from the direction of below, then images were transmitted to the host computer by 2.4 GHz wireless communication. Edge image of crack can be gained after the image processing program carried out smoothing filtering, adaptive binary and edge extraction for original images of bridge. Image processing program adopted Hough transform to extract the characteristic parameters of bridge crack in edge images including length, width, shape and location of crack. The result of accuracy verification test shows that the relative error of this system was in the range of ±5% and it satisfied the requirements of early crack detecting for bridges.

Abstract: Modern aircraft is designed generally with static unstable configuration in order to achieve the good maneuvering performance and the good controllability. Flight control law design is very important for the modern aircraft. The most importance for the flight control law is sustained flight. This paper presents a method of the state space description static instability mathematic model of modern aircraft. A new flight control law design based on pole placement and state feedback method is given in this paper also. The flight system stability and maneuverability are greatly improved through the method of the pole placement and state feedback. The simulation results show that pole placement method is very important and feasible in modern flight control system design.

Abstract: In decade years, several simple methods for the automatic tuning of PID controllers have been proposed. There have been different approaches to the problem of deriving a PID-like adaptive controller. All of these can be classified into two broad categories: model-based; or expert systems. In this paper a new expert adaptive controller is proposed in which the underlying control law is a PID structure. The design is based on the fuzzy logic and the generalized predictive control theory. The proposed controller can be applied to a large class of systems which is model uncertainty or strong non-linearity. Simulation results have also been illustrated. It shows that the proposed expert PID-like controller performed well than generally used PID.

Abstract: This paper presents an approach for solving the multidisciplinary topology optimization (MTO). To simplifying the description, a three-dimensional (3D) “heat transfer-thermal stress” coupling topology design problem is used as an instance to interpret the solving scheme. Unlike the common multiphysics topology optimization problem which usually modeled in a 3D domain or a 2D domain alternatively, the topology optimization problem mentioned in this paper has a 3D design domain (the design variable is referred as ρ₁) and two 2D design domains (the design variable is referred as ρ₂ and ρ₃) together in one mathematical model. Although all the model and solving method are based on a certain design instance, the solving scheme presented in this paper can be used as an efficient method for solving the boundary coupling MTO.

Abstract: For the characteristics of permanent magnet linear synchronous motor (PMLSM) hoisting system’s nonlinear, time-varying and vulnerable to disturbance, based on the established PMLSM d-q axis dynamic model, designed of an improved BP neural network PID speed controller. Modified the fixed learning rate in BP neural network to adaptive adjustable, and added the momentum to reduce the oscillation tendency in the learning process, greatly improved the convergence speed and avoided the network into a local minimum. Compared with the simulations of traditional PID and the improved BP network PID speed controller, the results showed that the improved BP neural network PID speed controller had the high quality and it can make the system with better dynamic performance and robustness.

Abstract: In this paper, we presented an equipment fault diagnosis method based on multi-sensor data fusion, in order to solve the problems such as uncertainty, imprecision and low reliability caused by using a single sensor to diagnose the equipment faults. We used a variety of sensors to collect the data for diagnosed objects and fused the data by using D-S evidence theory, according to the change of confidence and uncertainty, diagnosed whether the faults happened. Experimental results show that, the D-S evidence theory algorithm can reduce the uncertainty of the results of fault diagnosis, improved diagnostic accuracy and reliability, and compared with the fault diagnosis using a single sensor, this method has a better effect.

Abstract: Research on the vibration performance of the grinder measuring device and its anti-vibration ability is very important to improve the measuring and grinding accuracy of the roll grinder. According to the problems of real vibration test difficulty and too many unknown parameters for theoretical analysis, a method of integrating theoretical analysis and simulation test is put forward. A vibration analysis virtual prototype of the measuring device is built using ADAMS/Vibration, and then the system natural frequencies, mode shapes and frequency response are solved to conduct free vibration analysis, providing the base for the design and optimization of the measuring device.

Abstract: Nonlinear finite element analysis of twelve SRC (steel reinforced concrete) special-shaped columns using ANSYS programs was conducted and the mechanical behaviors of these columns were analyzed. A series of numerical simulation technologies such as defining the material model of the concrete /steel, establishing global finite element model with discrete reinforced bars/stirrups elements and the methods of post-processing of the results were investigated. A quick method of finite element model establishment was proposed to avoid unit not sharing nodes and grid division error during meshing, which would cause problems such as divergence of the model. The results indicate that the numerical simulation technology presented is feasible and can be applied to further research on mechanical behaviors of the SRC structures.