Advanced Materials Research Vols. 328-330

Abstract: The deficiencies of drum water level control system and unstable combustion of supercharged boiler could result some serious accident such as water level fluctuating greatly, pipes in furnace overheating and bursting, boiler loss water. In order to solve the problems, flame detect system was used to get flame images of boiler's furnace, and radiation energy signal was introduced into drum water level control system to add one auxiliary control loop of combustion side. The new control strategy was established and simulation model was set up. The simulation results show that the new control system could adjust feed water within 20s, and eliminated the disturbance of water level within 60s by way of monitoring radiation energy signal, the fluctuating range was also decreased significantly.

Abstract: Aiming at the difficult question of flaw qualitative analysis during industrial ultrasonic testing, a method of flaw classification based on the combination of wavelet packet transform (WPT) with artificial neural network (ANN) is proposed in this paper. Firstly, WPT is applied to feature extraction of ultrasonic flaw echo signals, and then BP neural network (BPNN), RBF neural network (RBFNN) and probabilistic neural network (PNN) are respectively used to perform flaw classification by means of the features. To validate the method above, some experiments of feature extraction and flaw classification are performed utilizing a series sample of butt girth welds of seamless steel tube with four types of welding flaws, such as crack, stomata, incomplete penetration and slag inclusion. The results show that the accuracy of flaw classification by three kinds of neural networks respectively reached to 91.25%, 92.50% and 93.75%, and the better classification effect is obtained.

Abstract: Genetic algorithm (GA), a kind of global and probabilistic optimization algorithms with high performance, have been paid broad attentions by researchers world wide and plentiful achievements have been made.This paper presents a algorithm to develop the path planning into a given search space using GA in the order of full-area coverage and the obstacle avoiding automatically. Specific genetic operators (such as selection, crossover, mutation) are introduced, and especially the handling of exceptional situations is described in detail. After that, an active genetic algorithm is introduced which allows to overcome the drawbacks of the earlier version of Full-area coverage path planning algorithms.The comparison between some of the well-known algorithms and genetic algorithm is demonstrated in this paper. our path-planning genetic algorithm yields the best performance on the flexibility and the coverage. This meets the needs of polygon obstacles. For full-area coverage path-planning, a genotype that is able to address the more complicated search spaces.

Abstract: Belt relaxation, which affects a lot on operation reliability of the fire smoke exhausting robot, is hard to detect. In this paper, a new method for belt relaxation feature recognition based on continuous wavelet transform (CWT) is proposed, and a vibration model which simplified the robot as a 2-dof forced vibration system under harmonic excitation is established. The vibration acceleration signal has been collected using the IEPE sensor and data acquisition card, experimental results verified the accuracy of the vibration model, and weak impact signal caused by the belt relaxation was distinguished, that testify the practicability of the CWT method in belt relaxation feature recognition.

Abstract: In partial discharge detection of transformer, supersonics detection method is applied widely. In the paper, a model of supersonics is established by MATLAB. Meanwhile, analyses about the relation between amplitude of sound pressure and discharge capacity and ultrasonic signal spectrum are implemented based on the model. By analyzing the partial discharge characteristics of ultrasonic signals, a suitable ultrasonic receiving sensor can be selected that meets the performance requirements. Therefore, detection band of sensor is determined. Meanwhile, the structure of the sensor and the selection of piezoelectric crystals are introduced in details.Finally,the design of ultrasonic receiving sensor is determined.

Abstract: An introduction on the algorithm Apriori and FP-growth is given. And their advantages and disadvantages are pointed out. The rule of mining transaction databases has two common formats, horizontal layout and vertical layout. Normally, algorithm using vertical database layout is often superior to those using horizontal layout. A new Eclat algorithm was brought out, which is an improvement of Eclat and show good performance with a lot of datasets.

Abstract: Error analysis of measuring instruments is a significant part in the process of measuring instruments design with which primary error factors influencing measuring accuracy can be obtained. In order to correctly analyze and evaluate the sensors errors, the influence on final measurement result caused by error factors of all parts should be taken into account. Electric error consist zero voltage error and power errors including amplitude errors, phase errors and frequency errors. It will be difficult and cost much to improve accuracy of measurement with hardware method. So error correction technology is employed to ensure system accuracy. This method not only improves accuracy effectively but also reduces manufacturing cost of measuring instruments. In addition, errors suppression technology based on error separation, error correction of the Ordinary Least Square (OLS) and negative feedback model is proposed. Improving Time­-grating displacement sensor’s measurement accuracy plays an important role in the mass production of Time-grating displacement sensor.

Abstract: A new energy-saving method with an energy regulation device (ERD) is presented. The ERD is composed of an accumulator, a proportional throttle valve and a safety valve. Due to the addition of the proportional throttle valve, the ERD becomes a flow-controllable element. It can adjust energy according to the system demand. The principle of energy regulation based close-loop variable-speed valve-controlled-motor is discussed in detail. And it can be conclude that the proposed close-loop scheme can gain a good response as the valve control system while the power is less obviously.

Abstract: To deal with the defects of the steepest descent in slowly converging and easily immerging in partialm in imum,this paper proposes a new type of PID control system based on the BP neural network, which is a combination of the neural network and the PID strategy. It has the merits of both neural network and PID controller. Moreover, Fletcher-Reeves conjugate gradient in controller can make the training of network faster and can eliminate the disadvantages of steepest descent in BP algorithm. The parameters of the neural network PID controller are modified on line by the improved conjugate gradient. The programming steps under MATLAB are finally described. Simulation result shows that the controller is effective.

Abstract: The automatic and intellectualized reconstruction is the important way to improve and expand the traditional instrumental function. The surface roughness is an important indicator of effecting parts and products performance. On the basis of using precision measurement technology, electronic technology and computer technology synthetically, the principle and method of the automatic and intellectualized reconstruction of JB-3C Type Surface Roughness Measuring Instrument is mainly introduced, which is to reconstruct the hardware circuit and develop function in view of the flaws that the data processing speed of the traditional instruments is slow and they can not print the curve very abundant and even that operating steps are complicated and other shortcomings. And we adopt Matlab and VC++ mix programming to gather, process, demonstrate, analyze and compute data, which has high applicability and performance price ratio.