Advanced Materials Research Vols. 139-141

Abstract: A kind of signal build mould and identification tool for roller of rolling mill was discussed. Basic algorithm of Hidden Markov model (HMM) theory was presented. For ψ500×2 shrewd roller of rolling mill, the paper led Short-time Fourier transform (STFT) into draw the feature of roller signal and chose Continues Gaussian Hidden Markov Model (CGHMM) to build and identify mould. The experiment installation major included: ψ500×2 shrewd rollers and roller performance test control work of rolling mill control machine as well as a set of online state inspection system. The experiment data was collected by two kinds: roller rotational speed from low to high and from high to low. The experiment shows that this system has better identification rate, and proves that this system is effective.

Abstract: Chlorophyll fluorescence (CF) has become a powerful tool in plant photosynthesis research and stress detection, considered a rapid, highly sensitive and non-invasive probe of photosynthetic activity. With the rapid development of computer technology and sensor technology for weak signal, recently much attention has been paid to chlorophyll fluorescence on-line monitoring for estimation of plant photosynthesis. This paper analyzes the fundamental principle of chlorophyll fluorescence on-line monitoring technology, introduces a new measurement and control system for chlorophyll fluorescence, which bases on MINIPAM, using light-emitting diode (LED) excitation by means of measuring the fluorescence parameters, and introduces application of active fluorescence measurement and passive fluorescence measurement in the study of the biological information monitoring in plant photosynthesis. Finally, the future development trends, the prospect and the difficulties of chlorophyll fluorescence on-line monitoring technology are discussed.

Abstract: At the basis of the adaptive lifting wavelet transform, a method was proposed for solving the problem of noise suppression of the wire rope damage signals. A wavelet with damage property was constructed via lifting scheme, that is,the adaptive update-filter and the adaptive predict-filter were designed using the statistics information of the wire rope damage signals. And the compromise algorithm between software-threshold and hard-threshold was used in the threshold processing. The traditional wavelet and the above proposed transform are applied in de-noising of the practical acquisition of wire rope damage signal. The contrast experiments show that the noise elimination with the improved lifting scheme is better than that achieved by traditional wavelet transform. Moreover, this presented scheme retains the effective information in the break signals and greatly improves the design flexibility and the process speed.

Abstract: Metal magnetic memory (MMM) method, based on the magneto-elasticity and mechanical effect theory, is a new nondestructive testing technology. This paper aims at the material property and failure analysis for steam turbine blade with MMM method. The failure blade and its fracture face are tested with MMM technology at workshop. It has been found that the MMM signal variation gradient of the crack transition zone in the fracture face is minimal, that of the crack initiation zone is in the middle, and that of the tear fracture zone is maximal. MMM testing results reflect material behavior degradation of the failure blade. In order to proof the MMM results, the dynamic stress of the steam turbine blade under the operation loading is calculated by WESTHOMES software and analyzed theoretically. It has proved the validity of the MMM method applied on material property evaluation and failure analysis for steam turbine blade.

Abstract: In order to realize remote monitor to the motion controller, a smart motion device with SIMOTION motion control system is researched. The application of virtual private network technology, combined with SCOUT tool, a remote control through Internet is used. This paper introduces the hardware and software of the motion control system, the structure and composition of remote control system and the core technology for specific steps. A detailed analysis of the application effect is shown. The result shows that the remote monitor system not only reduces response time of maintenance, but also saves a lot of human and material resources. Many enterprises design their smart motion device with motion controller as one parts of whole equipment. The application shows the feasibility of remote monitor to motion controller by using VPN technology for smart motion device.

Abstract: In this paper, an approach of rolling bearing fault diagnosis based on artificial immune system (AIS) is presented. The features extracted from vibration signals are normalized as the original antigens, and an advanced clone selection algorithm (CSA) is applied to train the antibodies. Then use the antibody set to recognize the faults online. The experiments on rolling bearing show the approach is effective and feasible.

Abstract: General expressions of crack perturbations are given with perturbation method. With the delta function to express the crack position at the simple beam, the expressions of cross-section rotary inertia and mass per unit length of the whole beam are founded, and then the transverse free vibration equation of the simple beam with a damaged crack is established. The first and second order perturbations are considered as the linear combinations of corresponding mode shapes of intact state, according to the boundary conditions, and theoretical solutions about eigenvalues and mode shapes of the damage state are finally obtained. One simple beam is taken as a numerical example to calculate the modal parameters; the effects of first and second order perturbations on the results are compared. It is believed that the approach proposed in this paper could provide the necessary theoretical background for damage identification in simple beam.

Abstract: In the process of equipment fault evolution, equipment's attrition probability is different, namely selective attrition may be produced. This paper describes one method based on selective attrition, which achieves the aim of forecasting its optimal maintenance time by analyzing and handling the data of monitoring equipment. There are mainly two steps: first, get each part’s probability value of selective attrition under the current condition in use of association rule algorithm, then take the obtained probability value as the input, and get the optimal maintenance time through neural networks modeling. This method employs the real-time and dynamic decision-making method and adjusts the optimal maintenance time in real time according to the information in the equipment’s operating process, making it more conform to the actual condition. The feasibility of this method is showed by a simulation example.

Abstract: The fatigue life prediction and reliability analysis of dynamic systems under random excitement are important topics in modern engineering design. However, the stress power spectral density and the formulation of fatigue life prediction of a component in a dynamic system must be known when one predicts its fatigue life. A method of simulating computation for the fatigue life of a dynamic structure is presented. The method is based on the concept of unit load stress matrix. According to it, the relationship between the stress power spectral density of a structure in a system and the response spectra of the system can be established. Based on this, the formulation of the fatigue life prediction which is decided by the random stress process is obtained. With this method, the stress power spectral density simulation and the reliability fatigue life prediction for the CW-200 type vehicle truck are made. The method is suitable not only for the running dynamic structure but also for newly designed dynamic structures especially.

Abstract: It exists in complexity and fuzziness in structure and failure character of engineering machinery complex system. To solve the problem, fuzzy theory was introduced into fault tree analysis, and then the steps, principles and methods of fuzzy fault tree are determined. Based on the analysis of engineering machinery typical engine systemic structure and fault criterion, a fuzzy fault tree is established. Used a fuzzy mathematics method of reliability analysis with fuzzy fault rate and the median method of fuzzy significance analysis, the fuzzy fault rate and fuzzy significance of parts and subsystems is calculated. The result indicates that this method can solve the fuzziness problem of failure criterion and data in fault tree analysis. The result provides valuable reference for the reliability analysis.