Applied Mechanics and Materials Vols. 190-191

Abstract: The dynamic characteristic of cable damage is calculated of Tianxingzhou long-span cable-stayed bridge. Firstly, a normalized natural frequency is defined and the affection of cable damage on normalized natural frequency is analyzed. Through comparative studies came to the following conclusion: the damage effect on the natural frequencies of different levels of cable mode are essential differences, thus establishing a description of cable damage model based on support vector machine, the different damage cases are used to train and recognize. The numerical example shows that the method can be effectively used to identify the damage of cable of long-span cable-stayed bridge.

Abstract: This paper designed an OFDM baseband signal transmission system, which adopted CORDIC algorithm, pipeline organization and high-speed floating-point butterfly unit to complete the customized FFT Processor, and the modulation of the signal was realized by enhancing modulation mode (64-QAM) in the adaptive modulation mode. Meanwhile, due to FPGA technology is reconfigurable and parallel, the signal has a higher transmission rate. The system used FPGA resources reasonably and integrated highly, simplifying the complexity of the system; eventually it was adapted to the EP2C35F672C6 chip of Altera, and can be normally operated in the clock frequency of 100 MHz; At the same time, this system the system has high flexibility and generality, simple structure, and good clutter suppression, so it has a certain application prospects.

Abstract: The wireless sensor network (WSN) is the development trend of the technology of sensor. This paper, based on the nRF905 wireless module, introduces a wireless temperature gathering and transmitting system. From RF modules and master control module, the hardware platform has been designed, beyond that, the paper introduces the temperature sensor network software design. The test show that the system is stable, and datas are reliable.

Abstract: In order to provide accurate and robust indoor location service for large-scale mechanical manufacturing, a sensor network consisting of laser transmitters and optical receivers is proposed in a distributed framework. Geometric model described by rotating plane equations is established, re-ceiver’s location algorithm is achieved by utilizing intersection constraint of multiple laser planes form different transmitters. A self-monitoring mechanism for sensor network is also presented by introducing redundant fixed receivers as reference. Experiment has shown that the measuring accu-racy of a minimal sensor network is better than 0.2mm and self-monitoring mechanism can effectively guarantee the accuracy of the measurement results.

Abstract: This paper presents the Bayesian analysis of the zero-failure data with double hyper parameters a, b. We take prior distribution of failure probability pi be its conjugated distribution—Beta (pi-1, 1, 1, b) and hyper parameter b as the uniform distribution in (1, c). With quadratic loss function, If pi  (pi-1, 1), the E-Bayesian estimation of pi is . When 0 < c < si, and satisfy (I) ;(II) . The results satisfy . The properties of E-Bayesian estimation are given. A Simulation example is discussed, which shows that the method is both efficiency and easy to operate.

Abstract: Analyzed the shortcomings of Elman network, the paper put forward a modified Elman network, combined Ant Colony Optimization (ACO) algorithm to train the modified Elman network, and implement trained NN (Neural Network) to fault diagnosis of engine gearbox. Using conventional ’frequency domain’ analysis method, modified Elman network fault diagnosis of the gearbox was carried out. The results proved that fault diagnosis of engine gearbox based on the modified Elman neural network and ACO has better precision and diagnoses gearbox effectively, which imp roves the effectiveness and quality of the diagnosis.

Abstract: Firstly, build the suspension-control-system model under the condition of elastic guideway, and design the controller. Secondly, design the Kalman forecaster based on model, and diagnose the fault by comparing forecasted value with real value. Finally, verify the effectiveness of this fault diagnosis method for suspension signal by simulation.

Abstract: Mechanical equipment fault diagnosis occupies an important position in the industrial production, and feature extraction plays an important role in fault diagnosis. This paper analyzes various methods of feature extraction in rolling bearing fault diagnosis and classifies them into two big categories, which are methods of depending on empirical rules and experimental trials and using objective methods for screening. The former includes five methods: frequency as the characteristic parameters, multi-sensor information fusion method, rough set attribute reduction method, "zoom" method and vibration signal as the characteristic parameters. The latter includes two methods: sensitivity extraction and data mining methods to select attributes. Currently, selection methods of feature parameters depend heavily on empirical rules and experimental trials, thus extraction results are be subjected to restriction from subjective level, feature extraction in the future will develop toward objective screening direction.

Abstract: Imaging the overhead transmission equipment with high-resolution is very important to intelligent inspection, which is the prerequisites for fault diagnose. The intelligent inspection system often takes traditional imaging process of data acquisition followed by compression, which leads to the waste of image data and memory resources. We adopt an imaging method based on block compressed sensing to image the transmission equipment, the simulation results show that even if we only compressively sampled with 12.5% of the fully acquired image data, the image still can be recovered with high quality.

Abstract: Large centrifugal water pumps are widely applied in various water-supply and drainage systems. The vacuum-pumping is pre-requisite for their start-up so that the intelligent vacuum-pumping detection device utilizing STM32F103 as the main controller was presented to realize the automatic control especially of unattended pumps. A differential pressure transducer was adopted to measure the vacuum degree in pump chamber. Afterwards, an electrical signal of corresponding value was output, and then entered the ADC of STM32F103 after conditioning. The threshold algorithm was introduced for the judgement whether vacuum-pumping had been accomplished. Actual applications indicated this detection device was feasible and reliable, and the judgement algorithm was simply implemented and performed well in practice.