Applied Mechanics and Materials Vols. 143-144

Abstract: In order to solve the difficulties for the electrical and electronic equipment in passing through the EFT/B test, a filter design method of the anti-EFT/B interference is presented, and the standard of parameter selection is given. The EFT/B interference source transfer function is given, based on the analysis of the EFT/B mechanism, and an equivalent circuit mode is established. An anti-EFT/B interference filter design is presented thorough the spectrum analysis of the EFT/B interference. Experiments show that the designed filter can inhibit the EFT/B interference effectively, and meet the requirements of electromagnetic compatibility at the same time.

Abstract: Phase coded radar signal is one of the pulse-pulse modulation signal in the radar system. Based on the characteristics of matched filtering, we theoretically analyze the basic principle of the phase coded compression radar system. In the Matlab platform, we set up a simulation model which is used for matching filter, when the radar transmitting signal is Barke code signal. The simulation results show that Echo signal can obtain certain pulse compression ratio. By the matched filter, the main lobe amplitude of 13 bits Barker code signal is 22 times the rate of side-lobe. 13 bits Barker codes by the matched filter have the maximum pulse compression ratio.

Abstract: By taking advantage of temporal and spatial remote sensing, the present paper was to map, identify and characterize urban heat island in rapid urbanization area of east China. For research areas including six metropolitan cities around Hangzhou bay in east China, urban heat island measurements were monitored from surface temperature maps at 1km resolution derived from MOD11A2 both day and night acquired in the year of 2005 and 2009. LST normalization with NDSTI was applied in order to quantify UHI spatial changes at four seasons. The result showed that urban heat island phenomenon expanded contiguously in the study area. Day change of UHI seems to be more chaos than night change due to day UHI influenced by both solar and human being activities. There was some kind of urban cool island phenomenon in winter when urban surface temperatures were to be -1 – 0°C lower than the ambient LST. Except for winter, other seasons' UHI during daytime changed from 0.5°C to 2.5 °C and nighttime strongly changed from 0.5°C to 5 °C in 2009. During the night, six cites' UHI roughly coincides and UHI in winter was the smallest and in autumn was the biggest one. The study provided causation and environmental awareness of urbanization to urban planners in future urban development.

Abstract: The optical waveguides are produced in LiNbO3 substrate of three-component acceleration seismic geophone by lithography. Three-component acceleration seismic geophone detects changes in the external acceleration by detecting phase changes in the optical waveguides. The performance of optical waveguide directly affects the performance of three-component acceleration seismic geophone. Therefore, it is critical to measure and reduce the transmission loss of waveguides. The advantages and disadvantages of LiNbO3 crystal are introduced. The production process of Ti:LiNbO3 optical waveguide and its performance are presented. Some information about the types of transmission loss of optical waveguide and the measurement methods of optical waveguide loss are provided.

Abstract: In the progress of product researching and developing, it is very necessary that the founding of virtual prototype. In the phase of circuit simulation, there is a big problem in system simulation, which is the absence of SPICE model of mixed- signal. While solving the problem, the self-making device model is very powerful to finish the 'Top-down' simulation by the advantage of VHDL-AMS language. To find the advantage of the VHDL-AMS language for analog system, this modeling method is also effective to describe the mixed-signal system's structure and action.

Abstract: The underwater opto-acoustic communication system for directional acoustic communication between an in-air platform and a submerged platform operating is important. The paper presents a new method to solve this problem with opto-acoustic technology, which combines high-energy laser, the opto-acoustic transmitter that optical energy is converted to acoustic energy at the water surface. The laser-based transmitter provides a versatile method for generating underwater sound. The acoustic pressure is linearly proportional to the laser power. The paper designed an experimental measurement system for the opto-acoustic communication. It made experiments for study on the waveform and spectrum characteristics of opto-acoustic signals. The paper also discuss the acoustic wave after optical breakdown in water with Nd:YAG laser pulses. The opto-acoustic signals can controll by adjusting the laser's parameters. The conclusion is that the opto-acoustic communication has some technical advantages. This system presents a change in the way communicational from the air.

Abstract: In strip tandem rolling process, there is always deviation between the center line of the strip and the assumed center line, which is called running deviation. In this thesis, based on the actual running deviation data of some aluminum strip rolling industry, we analyzed their chaos and fractal character, proposed one improved pattern classification based on the fuzzy c-average clustering, on basis of this method classified running deviation pattern, constructed adding weight zero-order local prediction method of strip truning deviation signal. After the s actual data test, the forecasting result achieves the desired accuracy.

Abstract: In the acoustic emission fault diagnosis, the acoustic emission sensors was installed on the bearing pedestal where near from the fault source so that can collected stronger fault AE signal, however ,sometimes, it is inconvenience for AE sensor installation. This paper proposed that install the AE sensor on the base for collect the fault AE signal, but the signal was weak, so carried on EMD first, and selected the former 8 IMF to construct the original feature, than carried on KPCA for dimensionality reduction and get the optimized feature. In this paper, taking bearing acoustic emission test for example, by compared the base fault feature with the bearing pedestal fault feature, verified that the method that the AE sensor install on the base is feasible.

Abstract: In the fault diagnosis of rotating machinery through vibration analysis of the base, the signal may be weak and impure since the vibration signal which collected at the base is far away from the fault source. In order to provide useful evidences for the condition monitoring and fault diagnosis of rolling bearing based on the base vibration signal analysis, the rotor-bearing-base system model is built by taking the Spectra Quest comprehensive fault simulation test-bed as the object, the harmonic response analysis of the entire system is done with finite element analysis software ANSYS, and the ideal locations where sensors are installed on the base are obtained. These will form the foundation for the condition monitoring and fault diagnosis of rolling bearing based on the base vibration signal.

Abstract: It is common for the imbalance-crack coupling fault in rotating machinery, while the crack information is often overshadowed by unbalanced fault information, which is difficult to extract the crack signal. In order to extract the crack signal of the imbalance-crack coupling fault, and realize the fault diagnosis, the paper mainly analyzes its mechanical properties, and then use wavelet packet to de-nosing, decomposing and reconstructing the acquisition of vibration acceleration signal, and then analyzing the characteristics of frequency domain of the fault signal by using the energy spectrum. So the experiment proved that analyze and dispose the acquisition of the fault signal by using the method of the energy spectrum and the wavelet packet, which can effectively distinguish between the crack signal and unbalanced signals in imbalance-crack coupling faults .It also can provide some reference for the diagnosis and prevention for such fault.