Implementation of Seismic Motion Monitoring System and Displacement Estimation Algorithm Using Triangulation Method

Author(s):  
Kyeongseok Lee ◽  
Jeongbin Seo ◽  
Suk Chan Kim
2015 ◽  
Vol 69 ◽  
pp. 61-71 ◽  
Author(s):  
Minhua Lu ◽  
Yanan Tang ◽  
Ruichao Sun ◽  
Tianfu Wang ◽  
Siping Chen ◽  
...  

2013 ◽  
Vol 558 ◽  
pp. 227-234
Author(s):  
Jong Woong Park ◽  
Sung Han Sim ◽  
Hyung Jo Jung ◽  
Billie F. Spencer

A displacement measurement provides useful information for structural health monitoring (SHM) as it is directly related to stiffness of the structure. Most existing methods of direct measurement such as the Laser Doppler Vibrometer (LDV) and the Liner Variable Differential Transformer (LVDT) are known to have accurate performance but have difficulties particularly in the use of large-scale civil structures as the methods rely on fixed reference points. Alternatively, indirect methods have been developed and widely used methods are Global Positioning System (GPS), vision-based displacement measurement system and displacement estimation from acceleration record. Among the indirect method, the use of accelerometer provides simple and economical in term of both hardware installation and operation. The major problem using acceleration based displacement estimation is low frequency drift caused by double integration. Recently, dynamic displacement estimation algorithm that addresses low-frequency drift problem has been developed. This study utilizes Wireless Smart Sensor (WSN) for estimating dynamic displacement from acceleration measurement in combination with the recently developed displacement estimation algorithm. Integrated into WSN that are low-cost, wireless, compatible with accelerometers, and capable of onboard computation, the displacement can be measured without limit of location on large-scale civil structures. Thus, this approach has the significant potential to impact many applications that require displacement measurements. With the displacement estimation algorithm embedded, the WSN performs in-network data processing to estimate displacements at each distributed sensor location wirelessly using only measured acceleration data. To experimentally validate the performance of displacement estimation using WSN for the use in structures with multiple-degree of freedom, the random vibration test is conducted on the three-story shear building model. The estimated displacement is compared with the reference displacements measured from the laser displacement sensor and the result shows good agreement.


2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xingxing Li ◽  
Lulu Song ◽  
Hao Wu

The status and role of science and technology in the field of modern competitive sports have become increasingly prominent. The construction of a scientific training command system is of great significance for improving the scientific level of the training process and deepening the digital cognition of ski training. This paper is based on the multisensor combination to conduct a digital research on cross-country skiing training, aiming to conduct in-depth research on the realization of human motion capture and the theory of motion inertial sensing. To build a scientific, formal, and malleable ski training program, the requirements for data acquisition, recording, and analysis are quite strict. For this, it is necessary to use scientific and reasonable tools combined with multiple algorithms to process information and data. During the experiment, accelerometers, gyroscopes, and magnetometers are selected as sensors to receive motion information, and recognition algorithms for identifying weightlessness, hybrid filtering algorithm, displacement estimation algorithm, and kinematic principles are adapted to process multisensor data using information integration technology. A human body motion model was established based on kinematic principles, and a cross-country skiing motion measurement program was designed. The experimental results show that, according to the combination of multisensing and video platform, the athlete’s posture prediction is adjusted, and the action on the track is more consistent, which can accelerate the athlete’s skiing speed and the size of the inclination angle to a large extent. It can affect the direction of the athlete’s borrowing force and the adjustment of gravity during the exercise. The tilt angle is expanded from 135° to 170°, and it can maintain good continuity during the exercise.


Author(s):  
Chengxing Zhai ◽  
Mike Shao ◽  
Renaud Goullioud ◽  
Bijan Nemati

Conventional centroid estimation fits a template point spread function (PSF) to image data. Because the PSF is typically not known to high accuracy, systematic errors exist. Here, we present an accurate centroid displacement estimation algorithm by reconstructing the PSF from Nyquist-sampled images. In absence of inter-pixel response variations, this method can estimate centroid displacement between two 32×32 images to sub-micropixel accuracy. Inter-pixel response variations can be calibrated in Fourier space by using laser metrology. The inter-pixel variations of Fourier transforms of the pixel response functions can be conveniently expressed in terms of powers of spatial wavenumbers. Calibrating up to the third-order terms in the expansion, the displacement estimation is accurate to a few micro-pixels. This algorithm is applicable to a new mission concept of performing mirco-arcsecond level relative astrometry using a 1 m telescope for detecting terrestrial exoplanets and high-precision photometry missions.


2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xinjing Xie ◽  
Jun Yang ◽  
Guoxin Liang ◽  
Chunxiang Li ◽  
Zhongyuan Li

To analyze the effect of real-time shear wave elastography (SWE) optimized by mathematical algorithms combined with thyroglobulin antibodies (TGAb) on the clinical diagnosis of differentiated thyroid carcinoma (DTC), a hybrid displacement estimation algorithm based on weighted phase separation and two-dimensional cross correlation was proposed. 102 patients with DTC were divided into a test group (TGAb-positive) and a control group (TGAb-negative). Real-time SWE based on hybrid displacement estimation algorithm was performed. Receiver operating characteristic (ROC) curve was adopted to analyze the characteristics of real-time SWE and its combination with TGAb to detect the sensitivity, specificity, and area under the curve (AUC) of the malignant degree of thyroid cancer. The results showed that the preoperative thyroid-stimulating hormone (TSH), thyroglobulin autoantibodies (TGAb), and thyroid peroxidase antibody (TPOAb) of TGAb-positive patients were higher than those of the TGAb-negative group ( P < 0.05 ). The preoperative tumors of TGAb-positive patients were multifocal, and the tumor size was larger than that of the TGAb-negative patients ( P < 0.05 ). The maximum Young’s modulus Emax of TGAb-positive patients was greater than that of TGAb-negative group ( P < 0.05 ). In addition, there was a very significant positive correlation between the patient’s TGAb level and Emax of Young’s modulus ( P < 0.001 ). The sensitivity, specificity, and AUC of the joint detection of real-time SWE Emax and TGAb for the malignant degree of thyroid cancer were significantly greater than those of the single real-time SWE and TGAb, and the difference was substantial ( P < 0.05 ). In short, joint detection of real-time SWE based on hybrid displacement estimation algorithm combined with TGAb had high sensitivity, specificity, and AUC for the diagnosis of DTC, which was suitable for clinical application.


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