Applied Mechanics and Materials Vols. 644-650

Abstract: An adaptive fault detection algorithm based on wavelet and SVM (Support Vector Machine) is proposed for LRE(Liquid Rocket Engine) turbopump real-time fault detection. The algorithm firstly divides the historical signals into some segments by reasonable step length. Then for each segment it gets M-layer detail signals through Daubechies wavelet transform. Thirdly it divides every layer into K average segments and calculates there RMS values, gets M RMS sequences of detail signals. After that it constructs M-dimensional RMS vector as fault feature by extracting RMS values at the same position in every RMS sequence, and extracts all the fault feature vectors of historical signal to construct SVM training sample set and then obtains SVM classifier. At last the classifier will be real-time updated by a reasonable method in the testing process to improve the classification accuracy. To validate the algorithm, a track of the vibration acceleration signal of a certain type of turbopump was chosen as the test object. The test results showed that the algorithm met its demands of accuracy and real-time performance.

Abstract: Through the analysis of specific test requirements, this topic design the overall architecture of the automatic test system. In the hardware design, this topic mainly discusses the hardware circuit design of the interface adapter. In the software design, this topic mainly discusses the secondary package of instrument module driver, the application development of interface adapter driver and test software. Finally, this system have been applied in the field more than once. It turns out that this system is able to test the performance indicators of units of radio, and the test results are accurate, the test efficiency is also high.

Abstract: Measurement matrix construction is important to compressed sensing. A novel method, MMC-DE (Measurement Matrix Construction based on Differential Evolution), is proposed in this paper. The matrix is based on the quasi-cyclic Low-Density Parity-Check (LDPC) code. This proposed method aims at constructing the quasi-cyclic matrix with the best girth during the optimization procedure. It can consequently result in improving the reconstruction performance of the measurement matrix for compressed sensing. Simulation results demonstrate that the proposed measurement matrix is better than the matrix of Tanner code and array code. It is also easy to implement and hardware friendly.

Abstract: According to the development status of large-scale PV power station, this paper expatiates the requirements of the monitoring and control system for the large-scale solar power station, and presents the method of wireless mesh network technology applied to the system. This paper analyses the architecture of the monitoring and control system, the technical characteristics of wireless mesh network and the communication band selection to present the system program design. The whole system is flexible and reliable, and will promote the efficiency of operation and maintenance of large-scale solar power station.

Abstract: Gait period detection, serving as a preprocessor for gait recognition, is commonly studied in the recent past. In this paper, we proposed a novel gait period detection method for depth gait video stream. The method introduces the concept of layered coding for depth images which decreases computational complexity. Furthermore, the extreme value of the sum of layered codes for gait sequence is utilized to judge the period endpoint, which is in accord with the naked-eye observation. In addition, gait recognition experiments on the TUM GAID database are conducted with the description of gait features of one single detected period by the proposed scheme using tensor representation. The high recognition accuracy verifies the effectiveness of the proposed depth gait period detection method.

Abstract: To evaluate the noise and emissions of combine harvest meet the national standards or not, a noise and emissions testing and analyzing system was developed based on virtual instrument. A high precision digital noise level meter and an opacimeter were connected to a computer via a RS232 cable, and used to detect the noise and emissions of a working combine harvester respectively. A measurement and control software was developed to collect, process and analysis the measured data automatically in real-time, and the experimental data also could be stored and printed when necessary. The analyzed results were shown on the software interface by curves and LED. To verify the stability and reliability of the system, a serial of tests were made with a Xinjiang-2A combine harvester, the results showed that this detection system meet the need of different kinds of practical applications.

Abstract: This paper proposes an end-to-end user perception integrated monitoring and analyzing system, the multi-network user perception data by using standard SDK (Software Development Kit), completely solve the terminal abnormal events and the user perception problems. At the same time, in the network layer, integrating and analyzing module to realize the signal filtering and ordering, completely solve the problem of large amount of data and high investment cost of signaling monitoring. The user perception client intelligent analyzed network abnormal event and reported can realize the whole process analysis, and resolve problems of difficult to obtaining customer perception and data reporting in the network management. The monitoring module and making unified analysis of gathered data in background, can realize real-time monitoring of real-time and comprehensive experience of network users, thus get means of improving users' network experience fundamentally.

Abstract: Electrooptic sampling has been shown to be a very powerful technique for making picosecond pulse waveform measurements of fast electronic devices and circuits. In this paper, we review the principles of electrooptic sampling technique for picosecond waveform probing with applications to characterizing 70GHz photodetector pulse response.

Abstract: In this paper, frequency-stabilized laser technology is introduced into photodetector frequency response measurement system. A 1531nm frequency-stabilized laser fulfilled by acetylene saturated absorption is employed to produce coherent light with a tunable laser source, gaining stable beat frequency light that reaches as high as several hundred ghz, fulfilling measurement of 40ghz high-speed photodetector frequency response bandwidth, and lowering impacts caused by instability of light frequency. In addition, measurement uncertainty analysis is conducted, which is better than 7 %(k=2).

Abstract: This paper consists of three chapters, first introduced the algorithm and methods of Face detection, and then focus on the SIFT algorithm, finally use SIFT achieve the face detection function.