Applied Mechanics and Materials Vols. 401-403

Abstract: Based on LabVIEW, vibration measurement and diagnosis system of equipment was developed for experimental teaching. On the platform, vibration signals from running equipment can be sampled, displayed, stored, and analyzed in time domain, frequency domain and time-frequency domain. The advanced signal processing technology such as power spectrum analysis, cepstrum analysis, demodulation analysis can also be executed. Using pattern recognition technology, the processed signals can be integrated for intelligent diagnosis of equipment state. The experimental system is helpful for students to learn signal processing methods, and to design virtual instrument.

Abstract: In Modern society, most of car engines are multi cylinder four stroke engines, rotate speed is an important parameter of the engine, engine running status is a comprehensive expression of engine operation condition. It is also the result of the interaction by the gas torque, load torque and inertia moment. So the speed measurement is of great significance. Car engine speed measurement method has a lot of kinds, this article is based on the vibration method to measure, different methods used in vibration signal acquisition, analysis, processing and implementation. The vibration of the automobile engine output signals are continuous changes over time, we can say is a continuous signal. The vibration of the automobile engine output signals are continuous changes over time, we can say at this time is a continuous signal, when we use vibration sensor to gather the signals, a certain number of sampling points that are in different time, same time interval the vibration data resulting from the sampling theorem. At this time we deal with discrete time signals [1, 3]. Because of various vibration interference, The useful information we want to extract has been hidden in a lot of vibration under the disturbance signal, therefore, we carried out on the vibration signal analysis and processing, converting vibration wave in the frequency domain analysis, combining the new method of machinery vibration signal feature extraction, using short time Fourier transform, multiple correlation theory and Hilbert Huang transform combined with the application, making us in post-processing can extract the characteristic signal under the strong noise background [4]. The original signal frequency is obtained, based on related formulas to calculate car engine speed.

Abstract: In this study, a non-load blanket device for heart rate detection was designed, based on the function of ballistocardiogram (BCG) to characterize each heart beat. A bed blanket with underlaid pressure-sensitive cables was employed to simultaneously collect the BCGs and record the amplitude as well as frequency of heart beat in real time. The noise jamming was reasonably eliminated according to the Mallat fast algorithm with characteristics of BCG retained in the process. The obtained results of ballistocar-waveforms with obvious characters and values of cardiac rate demonstrated that good effects could be obtained by our heart beat detection device. This study proves to be a significant attempt for the BCG application on physiological parameters detections.

Abstract: Because of the gun comprehensive performance detection means backward, and unable to meet the maintenance and support needs, we analysis on the artillery and comprehensive index. The detection system for the breechblock and anti-recoil mechanism and aimed machine is designed. Using advanced hydraulic control technology, realize the technical indicators detection under recoil process. The performance status before repair and repair quality are completely grasped. Its proved in the application this system runs stably and reliably.

Abstract: Since the widespread application of NC machine, fault diagnosis and repair of NC machine has been the subject of attention. Now both at home and abroad has a number of new concepts and methods to the field. The application of CBR technology in NC machine fault diagnosis analysis system is a very good exploration and research. Application of CBR technology is based on similarity of NC machine failure, using the method of case-based reasoning to identify the reference case, diagnosis method with reference to the case to find a reasonable solution. The CBR technology is applied to diagnose faults of CNC system, the accumulation of collection is convenient for the experts' experience, the fault diagnosis analysis system is more practical.

Abstract: This paper has proposed a new control algorithm based on wavelet neural network to control the Variable air volume Air Conditioning System with features of nonlinear and large lag. Using the wavelet neural network to predict the output variables online, and using the fuzzy RBF neural network as the controller to robust control the uncertainties of system parameters. Simulation results show that the algorithm proposed has good local predict ability for the nonlinear system, which is in full agreement with the mode. And it shows strong robustness and adaptability using the fuzzy RBF neural network to control the model gap in the running process of system.

Abstract: Remanufacturing is an important way to develop recycling economy. However, the quality reliability testing is a bottleneck for the recycled product. Metal Magnetic Memory (MMM) technology is a valid method for early damage testing based on the magneto-mechanical effect. This paper aims at quantitative identifying damage for the recycled pumping rod（RPR）. The MMM rules of RPR damage are found through fatigue experiments. By using four-dimensional MMM parameter vectors, that is, peek-peek value，differential gradient，integral gradient and energy, are marked the damages. Furthermore，a multi-level damage classification model has been established base on optimal multi-classification algorithm of support vector machine (SVM) for RPR. The relationship is given between the damage degrees and MMM signals, which provides a theoretical basis and engineering tool of RPR reliability evaluation.

Abstract: In this paper, the test bench for electric vehicle drive system is designed and the real-time display of speed, torque, current, voltage and other conventional parameters are realized that can offer lots of authentic data for motor performance evaluation, motor parametric design and optimizing control strategy. Road simulation is an important function in the test bench, so the paper analyses the driving electric vehicle in the longitudinal and gives the theoretical dynamometer dynamic output load values that can provide the theory reference for the further implementation of road conditions simulation based on LabVIEW. Finally, in order to validate the test bench feasibility, the start, accelerated and deceleration tests are implemented and show good performance of the bench.

Abstract: A crane strain acquisition system based on ZigBee wireless sensor network and WiFi is built to monitor the stress state of the cranes in real-time. The star topology is selected as the wireless communication architecture. The endpoint nodes are responsible for acquiring the strain data sampled by a time to digital converter PS021, and then sending the data to the gateway. The Gateway collects the data from the endpoint nodes and transfers the data to the host computer through WiFi network. Furthermore, the strain data are analyzed with the monitoring software. The static and dynamic strain data of a cantilever beam are obtained with the system, and the results show that the system works properly and is proved to be useful and feasible to monitor the crane stress state.

Abstract: This paper describes a speech coder which has an input signal frame interval of 20ms percent in duration, contains 160 voice samples (8,000 samples/s) and 48 bits. A key feature of the coder is a novel Line Spectral Frequencies (LSF) quantization scheme, requiring only 19 bits per frame. This new coder, through algorithmic improvements, enhanced quantization techniques and new harmonic synthesis method, produces better speech quality at 2.4 kb/s transnission rate than the new U.S. Federal Standard MELP coder.