Complex fluid velocity measurement can be achieved in a simple and direct manner using capacitive sensors and cross correlation algorithm. Measurement model and working principle are introduced in the paper. Sensor sp...
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ISBN:
(纸本)9780578576183
Complex fluid velocity measurement can be achieved in a simple and direct manner using capacitive sensors and cross correlation algorithm. Measurement model and working principle are introduced in the paper. Sensor spacing, "solidification" flow model hypothesis and signal acquisition noise are three main factors affecting the effectiveness and accuracy of measurement. And their influences are discussed by means of numerical simulation.
This paper proposes an idea of employing sparse reconstruction-based technique for thermal imaging defect detection. The implementation of the reconstruction technique is tested on a carbon fiber reinforced polymer te...
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This paper proposes an idea of employing sparse reconstruction-based technique for thermal imaging defect detection. The implementation of the reconstruction technique is tested on a carbon fiber reinforced polymer test piece with artificially drilled defects and the test results are compared with the established crosscorrelation method. The two processes are compared in terms of defect detectability, their SNR variation with defect depth and their computation complexity. When compared with cross correlation algorithm, the technique is expected to solve memory space problems by compressing all information from large cross-correlated pulse video into a single reconstructed image as an output. Furthermore, in existing crosscorrelation methods, the pulse peak time shifts with defect depth. Hence, defect quantification algorithms, such as SNR calculation, require multiple frame analysis. Such algorithms are comparatively simplified in sparse reconstruction technique. This paper explores sparse reconstruction algorithm for resolving close-spaced defects. This paper further describes cross-validation method for optimization of a user parameter in sparse reconstruction method.
The image quality and accuracy of the atomic force microscope are seriously affected due to drift and hysteresis of Piezoelectric positioning platform. Currently, the distortion correction methods had been confined in...
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ISBN:
(数字)9781510649941
ISBN:
(纸本)9781510649941;9781510649934
The image quality and accuracy of the atomic force microscope are seriously affected due to drift and hysteresis of Piezoelectric positioning platform. Currently, the distortion correction methods had been confined in tracking a certain area or image correction after images are acquired, which makes it difficult for the atomic force microscope (AFM) to obtain low distortion images. In this study, the scanning path of the AFM is redesigned. The scanning route is spiral in a whole with many blocks which are scanned once at a time, and the drift of blocks is corrected in real-time during the scanning process. This method is suitable for real-time correction of drift during long-time scanning, compared with the traditional scanning method.
In a multi-user direct sequence code division multiple access (DS-CDMA) system, retrieval of the transmitted signals with a conventional receiver is difficult when there is chip asynchronism, multipath propagation and...
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ISBN:
(纸本)0780374029
In a multi-user direct sequence code division multiple access (DS-CDMA) system, retrieval of the transmitted signals with a conventional receiver is difficult when there is chip asynchronism, multipath propagation and the associated near-far problem. The results show that despite these problems an adaptive linear receiver based on a mixed crosscorrelation and constant modulus algorithm (CC-CMA) has the potential to retrieve all users simultaneously. In this paper, we propose several algorithms based on Quasi-Newton type algorithms. Compared with the conventional CC-CMA algorithm, the proposed algorithms achieve faster convergence at low computational cost. Simulations support the improved convergence properties of the algorithm.
Parameter repeatability is a serious problem for manufactured quartz flexible accelerometer, which greatly determines the precision of measurement results. This paper presents a testing method for quartz flexible acce...
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ISBN:
(纸本)9781479970711
Parameter repeatability is a serious problem for manufactured quartz flexible accelerometer, which greatly determines the precision of measurement results. This paper presents a testing method for quartz flexible accelerometer under closed-loop condition, which helps protect pendulum. Testing results are processed by cross correlation algorithm which significantly improves the signal-to-noise ratio. Based on this, the least squares modeling method in frequency domain is given. The experiment and identification results indicate that the modeling method has advantages of high precision and practical engineering value.
Parameter repeatability is a serious problem for manufactured quartz flexible accelerometer, which greatly determines the precision of measurement results. This paper presents a testing method for quartz flexible acce...
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Parameter repeatability is a serious problem for manufactured quartz flexible accelerometer, which greatly determines the precision of measurement results. This paper presents a testing method for quartz flexible accelerometer under closed-loop condition, which helps protect pendulum. Testing results are processed by cross correlation algorithm which significantly improves the signal-to-noise ratio. Based on this, the least squares modeling method in frequency domain is given. The experiment and identification results indicate that the modeling method has advantages of high precision and practical engineering value.
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