Applied Mechanics and Materials Vol. 392

Abstract: For the parameter estimation problem of inertial instrumentation error models, a Bayesian network is founded to fuse the calibration data and make error coefficients statistical inference in this paper. First the fundamental of Bayesian network is stated and then how to establish network for a typical case of inertial instrumentation error coefficients estimation is illustrated. Since the difficult high-dimension integral calculus for model parameter can be avoidable, WinBUGS software based on MCMC method is used for calculation and inference. The simulated results show that using Bayesian network to make statistical inference for inertial instrumentation error model is reasonable and effective.

Abstract: The application of the HFRT (High-Frequency Resonance Technique), a demodulation based technique, is a technique for evaluation the condition of bearings and other components in rotating machinery. Another technique MED (Minimum Entropy Deconvolution) has been the subject of recent developments for application in condition monitoring of gear trains and roller bearings. This article demonstrates the effectiveness of the combined application of the MED technique with HFRT in order to enhance the capacity of HFRT to identify the characteristic fault frequencies of damaged bearings by increasing the signal impulsivity. All tests were done using data collected from an experimental test bench in laboratory. The Kurtosis value is used as an indicator of effectiveness of the combined technique and the results shown an increase of five times the original kurtosis value with the application of MED filter together with the HFRT.

Abstract: In theory, FMCW radar has very high distance measuring accuracy. While in practical system, the accuracy of FMCW radar is decreased due to the firm frequency sampling interval caused by using FFT to do signal processing. To solve this problem, basing on traditional FFT processing, this paper takes advantage of Chirp-Z transformation to partially detailing the main-lobe of echo wave distance frequency spectrum. Therefore, under the circumstance of smaller calculation, this method greatly has promoted the distance measuring accuracy and met the actual requirements of high accuracy distance measurement.

Abstract: This paper introduces a new close-range photogrammetric bridge deflection non-contact measurement method that has high accuracy and efficiency, and can be conveniently used by engineers without help from professional surveyors. After a general theoretical description (analysis process and program development) of a photogrammetric bridge deflection measurement method, the system configuration is introduced and the application is verified through the laboratory and field tests.

Abstract: In this study, we developed and evaluateda vibrator using a flat PCB-coil. The flat PCB-coil vibrator was fabricated on a printed circuit board using and etching process. The spiral pattern was etched on a fiberglass cloth with an epoxy resin. To evaluatethe flat PCB-coil vibrator, we generated a sine wave, saw-tooth, and square wave through a custom made wave generator and amplified the waveforms using a power amplifier. A three-axis accelerometer was used to evaluate the performance of the developed vibrator. Even though the developed vibrator is simple, it has a wide range of vibration frequency (50~500 Hz) and vibration amplitude (0~5 V). The vibration amplitude does not change due to frequency change. It is expected that the developed vibrator can be used in a wide variety of applications such as in a tactile stimulator, in elastography, energy harvesting, and in a cooling system.

Abstract: The reciprocating machinery has complicated structure, various motion forms and high difficulty of fault diagnosis, now we mainly apply the multi-sensor information fusion as the effective solution. This thesis introduces the structure model of reciprocating machinery information fusion, establishes the tree diagnosis model for fault diagnosis feature information fusion of reciprocating engine, describes the fusion diagnosis steps, and puts forward the technological approaches and methods to solve fault diagnosis information fusion of reciprocating engine from the aspect of testing methods and diagnosis modeling.

Abstract: The effective control of loads acting on shield tunneling machines is vital for the equipment operating security. The identification of shield machine loads is a non-linear multi-factor problem. This article proposes an identification method for shield machine loads by using the Particle Swarm Optimization (PSO) based Support Vector Machine (SVM). A PSO-SVM identification model is developed based on on-site data of a subway project. This model implements multi-parameter input related to loads, which reflects the mapping from loads to geological parameters and operating parameters during tunneling. The comparison between identification results and the on-site data verify the accuracy of the PSO-SVM method. This work can offer helpful references for the loads control.

Abstract: In this paper, a multi-function watt-hour meter which has the function of time-sharing charging, remote meter reading and IC pre-payment is put forward.ADE7755 is the heart of measurement circuit which can sample the voltage and current of the usercircuit,calculate the instantaneous power,real time clock chip DS1302 in the system which can provide accurate standard of time for time-sharing charging, the nonvolatile memory AT24C04 is used to store the electric power bill information and other working parameters, the infrared communication interface is used remote meter reading. The whole watt-hour meter is a pure electronic measuring instrument without any mechanical part, it is working reliably, simple and flexible in use.

Abstract: Through analysis of 66KV, 31500 KVA transformer tangled winding connector open welding faults, the coordination of Oil chromatographic analysis and electrical test can be used to find the defect and the location. It clarified the tangled windings of the transformer joint diagnosis of full open welding process in detail, and pointed out the direction for the future to find and the troubleshooting.

Abstract: General harmonic detecting scheme is using the Fast Fourier Transform (FFT) for detection of all the harmonics (such as 1 to 50 times). While power units often do not care about the specific values of all the harmonics, but is only concerned with some key harmonics or several overall indicators. For the above reason, a new harmonic detecting scheme based on the algorithm of BP neural network is presented in this paper. It does not need to calculate all the harmonics, when the detection of individual indicators or overall indicators which are concerned by users can be achieved,and to achieve the above-mentioned detection target, by the analysis of computation of BP, DFT and FFT algorithm, the superiority of the scheme in terms of computation is proved. After the simulation of the scheme using a set of measured harmonic data, the results validate that the above scheme is simple and feasible, and its detecting accuracy is close to which of FFT.