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This paper presents a novel flexible eddy-current probe specifically designed to inspect small defect for material with planar or complex geometry. The proposed eddy-current probe has a planar design and a multilayer structure using flexible printing circuit board technology. The fundamentals on the sensor operation are presented and explained in the presence of a metallic part to be inspected with...
There are some challenges in Electromagnetic Nondestructive Testing (EM NDT) techniques. Micro cracks are too small to find and evaluate at the beginning. Complex components are hardly to inspect. The volumetric sensor is difficult to be embedded in the structures. To solve these problems, Micro-Electro-Mechanical Systems (MEMS) was presented to fabricate micro inductive coils as eddy current sensor...
In this paper, time-reversal with multiple signal classification (termed TR-MUSIC), the widely used time-reversal based imaging algorithm, has been introduced into the area of ultrasonic NDE. This method can break diffraction limit which is given by Rayleigh criterion and achieve super resolution imaging. Here, resolution means the ability of an imaging method to resolve closely spaced targets. A...
Magnetoresistive sensors have plenty of applications in magnetic sensing areas, but magnetic and nonmagnetic 1/f noise severely degrades their low-frequency performances, especially detection sensitivity with hundreds of loss. In this paper, vertical motion flux modulation scheme with a piezoelectric silicon bridge is recommended for 1/f noise reduction, due to its effectiveness, simplicity and stability...
Ideally, the output total value of three-axis magnetometer is stable at a certain place no matter what direction the three-axis magnetometer is placed. Actually, diversionary error of the three-axis magnetometer can not be avoided. In stable magnetic circumstance, tradional LMS adaptive algorithm is with good performance to calibrate the three-axis magnetometer. Experiment result indicates that diversionary...
Step-size is the most important parameter in LMS adaptive algorithm, which directly influences the performance of adaptive filter. In this paper, filter parameter is theoretically calculated and subsection various step-size (SVSS) is introduced to improve stability of adaptive filter. Simulation results indicate that the new method of SVSS can solve well the contradiction between convergence rate...
Conventionally, a neutral section is operated manually by drivers according to break/close markers along railways, when an electric locomotive is passing the section. Because of the increase in trains' speed, neutral section passing control devices with magnets on ground and onboard detection coils are used in some countries. This paper presents a new automatic onboard neutral section passing control...
Multi-frequency eddy current test (MFECT) is an important NDT technology, and it can be applied to realize multi-parameter detection and interference elimination effectively. Aiming at the problem that conventional single-frequency eddy current test can only identify defects but can't classify defects effectively, a new MFECT technology which adopts LFM signal exciting and spectrum analysis method...
Schematic of a new type of Mach-Zehnder interferential magnetic sensor is illustrated. TbDyFe is used as the magnetostrictive material which is coated on the round surface of the sensing optical fiber. The deposition experiments are done using electron beam evaporation system. Three main process parameters, temperature, vacuum and deposition rate, which affect the TbDyFe deposition quality seriously,...
A sensitive DC magnetic field sensor based on magnetostrictive straining of optical fibers was demonstrated, which utilizes alternating current phase tracing (PTAC) homodyne scheme to eliminate phase drift. Comparison was carried out experimentally between direct current phase tracing (PTDC) and alternating current phase tracing, then expressions were presented. The results showed that the PTAC had...
Nowadays digital scanning techniques are widely used in many fields such as medical imaging and office affairs. In order to achieve fast and accurate text image acquisition and recognition, a new digital scanning pen as well as some image processing techniques is developed in this paper. An adaptive image division algorithm based on potential function clustering is achieved by the combination of total...
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