Abstract: To effectively avoid the loss of useful information, in this paper, we extract feature information from the fault signal of rotating machinery in different aspects such as amplitude-domain, time-domain and time-frequency domain. Then for the multi-dimensional feature extraction is prone to the problem of “dimension disaster”, introduce the principles of FDR in data mining to determine the classification ability of each individual feature, and introduce the cross correlation coefficient to solve the problem that dealing with individual feature neglects the interrelationship between the features, and construct a new feature level data fusion algorithm. Finally, According to the characteristics of the HMM (Hidden Markov model), SVM (Support Vector Machine) and its hybrid model, we construct a new decision-level data fusion model.
Abstract: The tension causes pulley eccentric in belt drive. Through the analysis of the shaft deformation caused by the pulley eccentric, this paper resulted in the calculation method and related formulas for belt drive rotary motion error under different tension. And based on the PDJ-4 belt drive experiment facility giving examples of analysis, we draw the conclusion that with the increase of tension, rotary motion error increases at the same time. Thus it will have a greater rotary motion error when the tension is too large. This paper proposed the scheme and measures to improve that error eventually.
Abstract: The paper reviews the research results of the fan noise in recent years, including both achievements acquired and problems existed. The domestic and overseas researches of fan noise mechanism mainly focus on air dynamic noise. However, the fan noise control method expounds the problem from three aspects, namely, the modern design manufacturing application in noise reduction, new material new structure used in noise reduction, and active noise reduction. Finally, the paper prospects the main development direction of fan noise reduction.
Abstract: After the traffic accident, it needs to confirm the cause and responsibility of the accident, and whether the bad brake performance is the important reason for the accident. At first, this paper has put forward the road test standard of the brake performance and comprehensively analyzed the braking process. Except the theoretical analysis, this paper has made a quantitative research on the influence of people, vehicles, road, environment and testing instrument on the brake result of the road test with the experiments and put forward some suggestions to reduce the influence of the test results.
Abstract: This paper analyzes the simulation results obtained by using FLUENT 6.1, simulation being carried out on supersonic inlet. A combination of turbulence models are adoptedsuch as k-RNG k- and S-A. The computation outcomes are checked by experiment results. Detailed analysis demonstrates that the numerical results obtained from the turbulence models can accurately forecast the pressure distribution trend in the inlet. However, for separation bubbles due to the mutual interference of the shock wave within the inlet boundary layer, the calculation predicts fewer bubbles than actually generated in the experiment. The RNG k- and SA turbulence models produces clearer wave structures in the channel.
Abstract: In order to investigate wind load for long oblate chimney, a commercial computational software “Fluent” was employed to solve the time-averaged k-ε turbulent flow model for Realizable form. The flow structure and surface pressure distribution on the long oblate chimney upon facing wind was obtained for the wide-face and the narrow-face, respectively. The windward side of long oblate chimneys bears positive pressure, while the largest negative pressure area is on both sides of chimney. The characteristics of the wind pressure distribution were explained by analyzing the flow around the chimney. These discoveries can be used as a reference, for the new version of the wind load criteria.
Abstract: Huang’s data-driven technique of Empirical Mode Decomposition (EMD) is presented, and issues related to its effective implementation are discussed. Integrating signal directly will produce a trend, it will cause distortion and interfere with the calculation results. This paper discusses the reasons that cause the integrated signal trend, compares the different methods for extracting trend. The traditional steps use the linear fitting and a high-pass filter to remove low frequency signal to extract trend. This paper uses Empirical Mode Decomposition (EMD) method to extract integrated signals trend, discussed the advantages of Empirical Mode Decomposition (EMD) method in this case, proves that Empirical Mode Decomposition (EMD) has a good application in integrated signal trend extraction.
Abstract: Expert system is a smart program system, which can utilize the human experts' knowledge and experience from solving problems to deal with difficult problems of high level in correlative fields, so as to solve the fault diagnosis problems of complicated systems. This paper in detail introduces the composition and function of equipment-oriented fault diagnosis expert system and the meaning of the application of this system in equipment fault diagnosis. In wartime, the location of the equipments is more dispersed and the battlefield environment is harsher. These above make manual inspection more difficult, of no guarantee of time effect and maintenance difficulty bigger. The utility of the fault diagnosis expert system for equipment has important meaning in both ensuring the ability at equipments' development, maintenance and repair and improving the utilization rate of equipments and the army's combat effectiveness with national defense science and technology.
Abstract: A particular subset of 6-DOF parallel mechanisms is known as Stewart platforms (or hexapod). Stewart platform characteristic analyzed in this paper is the effect of small errors within its elements (strut lengths, joint placement) which can be caused by manufacturing tolerances or setting up errors or other even unknown sources to end effector. The biggest kinematics problem is parallel robotics which is the forward kinematics. On the basis of forward kinematic of 6-DOF platform, the algorithm model was built by Newton iteration, several computer programs were written in the MATLAB and Visual C++ programming language. The model is effective and real-time approved by forwards kinematics, inverse kinematics iteration and practical experiment. Analyzing the resource of error, get some related spectra map, top plat position and posture error corresponding every error resource respectively. By researching and comparing the error spectra map, some general results is concluded.
Abstract: The phenomenon of higher shaft vibration and higher bearing temperature is repeated happening during the starting of the 1 000MW coal fired unit of Suizhong power station, seriously endanger the safe operation of the unit, this article mainly aims at the difficult problem of this one technology, by researching on steam turbine work principle and vibration analysis, to find the reason of effect on stability, and to correct all unreasonable factors, to ensure the safe and stable operation of the unit, to laid solid foundation for the construction of the intelligent power grid.