Vibration, Structural Engineering and Measurement II

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Authors: Xin Jing Wang, Zhen Qi Hu, Yan Ling Zhao, Yu Ming Guo, Pei Jun Wang
Abstract: Using the ground-penetrating radar (GPR) system with the different frequencies and neutron probe, combing with radar image interpretation and the amplitude spectrum, the impact of GPR detection effects on the soil taxonomy and underground pipe were analyzed. The results indicate that when the soil content is 17.02%, the effect on soil taxonomy of 750MHZ antenna is better than 400MHZ, but the effect on underground pipe is same. As soil water content increases to 25.333%, the soil taxonomy of two antennas’ detection tends to same, and “fake stratifications” existed. The soil water content accelerates to 36.389%, the detection effect on soil taxonomy and underground pipe is so poor. Attenuation mechanism and propagation characteristics of the high electromagnetic wave were presented to interpret those phenomena. The above analysis shows that the soil water content is one of the main prerequisites for the applications of GPR. Some indicators could be provided to nondestructive test in land consolidation project quality by GPR from this research.
Authors: Jun Nan Xiong, Shan Liu, Yan Mei Yang, Ze Gen Wang
Abstract: Extracting residential area from remote sensing image is an important issue in remote sensing mapping, disaster assessment, city planning and other field. In this paper, the existing residential area extraction method are analyzed at first, including the method of threshold structure in the spectral, combination knowledge discovery and spectral structure, NDBI, NBI and IBI ; Then, the differences of Spectral characteristic and how to distinguish residential area and other land use type are discussed, the extraction model is build based on the above research. Taking Jiaxing City, Zhejiang Province as an research area, residential area are extracted from ETM+ image use NDBI index and Spectral structure difference. At last, precision analysis indicate location accuracy is 85% ,area accuracy is 88.8%, the result show this method can improve the divisibility of residential area, bare land and road. The extraction result can provide data for remote sensing mapping, disaster assessment, city planning, etc.
Authors: Hu Sheng Guo, Bin Yan, Zhi Dong Wu
Abstract: The performance of the Ocean Bottom Seismometers (OBS) in seismic wave field measurement is vital to seismic exploration. In order to improve the performance of OBS, we have been developed a new Ocean Bottom Seismometer based 3-component MEMS accelerometer sensors. In order to sample seismic data synchronously, we have been designed multichannel A/D unit under the control of MSP430.We also are involved in a handle and sophisticated equipment allows to storage sampling data in the SD card module. The system based MEMS sensor are compared with conventional analog moving coil geophones, the result shows that the new measurement system with the advantage of high dynamic range, low noise and anti-jamming that suit for the high resolution seismicity information. The paper show that the new digital OBS using MEMS accelerometer will replace the tradition OBS in oil exploration, scientific research and seabed surveys.
Authors: Xiao Rui Wang, Xiao Qing Zhang, San Shan Jia
Abstract: In order to accurately reduce the equivalent defect error and draw the AVG curve, the relational expression between the sound pressure and the beam path was deduced, which was based on the ultrasonic sound field theory, the complex-variable function and the quadric surface integration. Then this curve was implemented by using the hardware and the software which were based on the above theory. In addition, it was analyzed the factors of attenuation coefficient and fitting the curve--Lagrange interpolation, to reduce the method error. Finally, the analysis of testing data shows that: the AVG curve which is made by flat-bottomed hole can accurately measure the equivalent aperture and reduce the data error, after giving full consideration to the attenuation coefficient factors and curve fitting.
Authors: Hou Tian Zhang, Lei Hu
Abstract: With the development of the city, there has more and more high rise buildings, people has serious attention on the security problems of the high rise buildings. Code for deformation measurement of building and structure asks that, deformation monitoring for high-rise building during service stage is necessary. During servicing stage of the high-rise building, owing to the change of site conditions, it is difficult to use former monitoring way. GPS plays a incomparable role in the deformation monitoring during the servicing stage for its advantages of high precision, fast speed and easy operation. This paper introduces the monitoring way and data processing of using GPS for high-rise building during servicing stage, using a example to prove that the application of GPS in deformation monitoring for high-rise building during servicing stage is feasible.
Authors: Ting Chen Jiang
Abstract: Wide Swath InSAR is known as WSInSAR which can use ScanSAR mode of SAR satellites to get geometrical information of the earth’s surface.ScanSAR’s character is that synthetic aperture time is shared by circumjacent sub_swaths and azimuth resolution is reduced so that large area deformation monitoring for earthquakes is realized.For imaging principle ScanSAR and IM mode are different, process of interferometry also have a lot of dissimilitudes such as coherence,coregistering,correction of atmosphere effects and geoid undulation. In order to make use of ScanSAR data to get wider deformation field,key techniques of ScanSAR interferometry are studied and analyzed in the paper.In the end, 405km×405km deformation fields of Wenchuan earthquake are gained by using ENVISAT ScanSAR data, With the application to ScanSAR interferometry in Wenchuan earthquake, it is significant for earth science research such as large earthquakes and crustal motion.
Authors: Jun Pu Wang, Fu Wan, Jiong Liu, Hong Xiang Sun, Hui Zhang
Abstract: The importance and urgency for security condition monitoring of the in-service derrick is more and more people paying attention. Based on the FBG sensing technology developed a derrick stress monitoring system. The derrick stress monitoring system, composed by the derrick, a certain number of series of FBG sensors, sensor cables, signal demodulation devices, a portable computer that including a central processing and control platform. Carrying out study in the the ZJ70 model derrick. The experimental results show that the set of strain measurement system has good linear characteristics, repeatability and high sensitivity. Can satisfy the derrick stress monitoring requirement, can realize derrick stress real-time, online, continuous monitoring, expanding the development and application of optical fiber sensing technology in the field of the derrick structure monitoring.
Authors: Tao Huang, Jun Pu Wang, Fu Wan, Shao Wei Chen, Yao Dong
Abstract: Aiming at the design feature and the operating of K-type derrick, an effective method used to stress real-time monitoring consider environmental loading is proposed. The challenge to the South China Sea offshore drilling derrick is a illustration. The derrick corrosion and wall thinning conditions is be considered, then using finite element software analyze derrick structure of static analysis, get the higher force about main member of derrick. Based on finite element analysis, select the key parts layout of measuring points, then monitor derrick stress under nine storms environmental loading and extreme work condition. The measured data results show that: the nine storms environmental load affect capacity of drilling significantly, the different parts of the main member stress have the different degrees of influence by environmental load, the maximum can reach 50.8%. This real-time monitoring method of stress, can protect the safety of marine operations, has a certain value of engineering application.
Authors: Hua Lei, Ping Yu Zhu, Hong Qiang Liang, Guo Qin Hou
Abstract: Distributed optical fiber sensor as the basis for temperature difference and strain identification, it has some advantages on deformation monitoring and seepage monitoring of the dams relying on long distance, continuous monitoring ability, distributed performance, strong anti-interference ability and other characteristics that traditional sensors do not have advantages. Taking layout of layered installation for example, this paper studies the relationship between laying bending radius and the strain sensing characteristics of the optical fiber sensor. The test of through the indoor simulated experiment and the outdoor dam model monitoring shows that the distributed optical fiber sensor for dam danger monitoring has good effect and promising applications. The dam model provides experimental platform to further study early warning criterion of dam hidden disaster.
Authors: Zhao Ran Meng, Wei Qiang Zhang, Hui Sun
Abstract: An experimental study of the underwater sound produced by single drop impacts influenced by different wind speeds, free fall heights and drop sizes at different depths is described in this article. Three kinds of acoustic radiation named impact sound, irregular bubble sound and delay bubble sound are distinguished by the pressure time trace. The images of bubbles taken near the point where the drop falls into water are shown. Some statistics laws of initial impact sound and irregular bubble sound affected by different condition included wind levels, heights of free fall and drop sizes are concluded. The directionality of initial impact sound is measured with wind and no wind. The process of delay bubble entrainment is analyzed and the measurements of bubble excitation probability in different condition are listed.

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