Advanced Materials Research Vols. 490-495

Abstract: Fault diagnosis of analog circuits is essential for guaranteeing the reliability and maintainability of electronic systems. Analog circuit fault diagnosis can be regarded as a pattern recognition issue and addressed by Multi-class SVM. A novel diagnosis technique based on linear discriminant analysis and one-against-one SVM is proposed in the paper. In order to obtain a good SVM-based fault classifier, the linear discriminant analysis technique is adopted to capture the major fault features. The extracted fault features are then used as the inputs of one-against-one SVMs to solve fault diagnosis issue. The effectiveness of the proposed approach is demonstrated by the experimental results.

Abstract: This thesis demonstrates a systematical analysis of factors resulting in unsafe events in air traffic control with gray correlation method. According to the case study of one ATM Bureau from 2004 to 2008, most of the human factors are attributed to communication problems between pilots and controllers. Therefore, this research is of great practical significance in improving and perfecting the safety management of air traffic control system.

Abstract: The concurrent nucleation and growth in a diffusion-controlled phase transformation is studied using the quantitative phase field method, and the transformation kinetics is obtained for a model alloy. The simulation results show that the simultaneous nucleation and growth of new phase can be described very well in the phase field model, and that the phase transformation is governed by the diffusion of solute atoms. The competition between nucleation and coarsening is also observed. The phase transformation kinetics is found to obey the JMAK equation.

Abstract: This paper discusses the fractional-order controller of heating-furnace system, a new PID controller of heating-furnace system based on fractional calculus will be considered. Classical PID control method is also studied. Then, this paper presents the fractional-order PID control method based on integer-order model of heating-furnace system. Meanwhile, simulation study is done. Comparing the control methods and strategies of integer order model of the heating-furnace system, a conclusion is drawn that PID control based on fractional calculus is much more complex than that of integer order controller. Numerical simulations are used to illustrate the improvements of the proposed controller for the integer-order heating-furnace systems.

Abstract: In order to improve the ability to predict the manufacturability of the free-form surfaces, the complexity of geometries for free-form surfaces is defined and studied. The free-form surfaces are modeled, which is used to calculate the distribution feature values of the surfaces. According to the feature values, free-form surfaces are classified into several clusters based on the fuzzy clustering algorithm. Group patterns are established according to feature values of the samples in the clusters. Then, the method of fuzzy pattern recognition is used to evaluate the surface complexity. The surface samples in the same cluster have close geometry configuration, so they often have similar manufacturing processes. A case study shows that the method can quickly classify the surfaces, largely reflecting the complexity of the free-form surfaces, which can lay the foundation for manufacturability evaluation of the complex surfaces.

Abstract: In this paper, we considered the problem of distributed power control for cognitive satellite networks. We defined a utility function that measures the user’s satisfaction, as a function of signal to interference plus noise ratio. And then a distributed power control algorithm was proposed based on the defined utility function. This algorithm can guarantee the protection of the primary user and meet quality of service requirements of the cognitive users. Simulation results show the performance of the proposed power control algorithm.

Abstract: Integrated guidance and control law is developed for high-maneuvering missile in order to minimize the uncertain dynamic couple between guidance loop and control loop. After building up the integrated model of guidance and control through combining guidance equations and autopilot equations, this paper puts forward a type of subspace control law with attack-angle tracking by using subspace stabilization control method. Finally, the simulation results by an example, which designs the integrated controller for a terminal guided missile, are presented to reveal that the integrated system has good dynamic-tracking performance.

Abstract: Compared with wavelet transform, Curvelet transform has characteristics of anisotropy and good curve singularity expression abilities. To advance the validity and reliability of wear particle feature extraction as well as recognition, an image feature enhancement method based on Curvelet transform was proposed. Wear particle images were decomposed into different frequency components by Curvelet transform. Scale enhancement coefficients were introduced into the medium-frequency and high-frequency components to enhance images’ edges and details. Then, enhanced wear particle images were achieved utilizing inverse Curvelet transform. Experiment results indicate that the proposed method can effectively improve image quality. As the details and edges are clear, enhanced images are more suitable for feature extraction and recognition.

Abstract: It is important for assemble industry to generate an optimized assembly sequences. In order to solve this problem, firstly an oriented mating graph model is proposed with the related mating matrix. Therefore an improved simulated evolution algorithm is proposed, which can compute an energy function of the assembly cost associated with the assembly sequence deduced by the graph model. The energy function can be optimized iteratively and perturbed occasionally by the simulated evolution until no further change in the energy occurs. Finally, the validity of the method is proved by a typical case.

Abstract: AD7715 is a high accuracy A/D converts chip made by American company Analog – Devices which involves a programmable gain amplifier, a programmable digital filter. It employs the Σ-Δ ADC technology to realize the 16-bits accurate measurement. The voltage meter uses 89C55 SCM as control, uses analog switch to conduct multi switch for measured voltage through signal conditioning, uses new 16-bit A/D convert to sample measured voltage being conditioned, uses 128 X 64 dot-matrix LCD as display screen to show the wave and Chinese words. This article mainly introduces the means of applying AD7715 chips to design accurate voltage meter.