This research proposes a visual inspection systems using sequences of monochromatic light sources. The proposed method focuses on the examination of molded plastic parts. A sample is illuminated by a succession of 7 c...
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ISBN:
(纸本)9781665432320
This research proposes a visual inspection systems using sequences of monochromatic light sources. The proposed method focuses on the examination of molded plastic parts. A sample is illuminated by a succession of 7 colored lights and for each configuration a picture is taken. Then, in order to spot potential flaws within a part, its images are analyzed using an inspection program based on statistical processing. For every part tested, the precision of the inspection was evaluated from the aggregation of results obtained with each light. Throughout the experiments, it was observed that the accuracy of the system had increased: exposing its targets to a series of monochromatic lights made it able to perceive more features than when it solely relied on a white illumination.
We have studied a non-contact nondestructive acoustic inspection method to detect internal defects of concrete structures using a long range acoustic device (LRAD) and a scanning laser Doppler vibrometer (SLDV). As an...
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ISBN:
(纸本)9781538633830
We have studied a non-contact nondestructive acoustic inspection method to detect internal defects of concrete structures using a long range acoustic device (LRAD) and a scanning laser Doppler vibrometer (SLDV). As an actual concrete structure, we measured the concrete floor slab of a huge bridge from a distance of about 33 m. And an internal defect of concrete was detected and visualized. Next, for a railroad tunnel, measurements were made from a distance 5-7 m. In data process, a healthy part of concrete was statistically analyzed. The difference in concrete state between a ceiling and a sidewall was evaluated by two acoustic feature quantities calculated from our measured data. We also measured the strength of concrete by Schmidt hammer and the elastic wave velocity. Both acoustic and physical feature quantities show a tendency of the same phenomenon. Obtaining the state of concrete, such as hardness, is to evaluate a healthy part of concrete. It can be done by using two acoustic feature quantities such as vibrational energy ratio and spectral entropy obtained from our measurements. In addition, in order to detect internal defects of concrete, it is important to grasp the distribution state of acoustic features quantities for a concrete healthy part.
In this paper, we present a tire defect detection algorithm based on sparse representation. The dictionary learned from reference images can efficiently represent the test image. As the representation coefficients of ...
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In this paper, we present a tire defect detection algorithm based on sparse representation. The dictionary learned from reference images can efficiently represent the test image. As the representation coefficients of normal images have a specific distribution, the local feature can be estimate by comparing representation coefficient distribution. Meanwhile, a coding length is used to measure the global features of representation coefficients. The tire defect is located by both these local and global features. Experimental results demonstrate that the proposed method can accurately detect and locate the tire defects.
Incorporating the finite-element method for the modeling of the SQUID NDE response to a predefined defect pattern, an adaptive algorithm has been developed for the reconstruction of unknown defects using an optimizati...
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Incorporating the finite-element method for the modeling of the SQUID NDE response to a predefined defect pattern, an adaptive algorithm has been developed for the reconstruction of unknown defects using an optimization algorithm for updating of the forward problem. The defect reconstruction algorithm starts with an initial estimation for the defect pattern. Then the forward problem is solved and the obtained field pattern is compared with the measured signal from the SQUID NDE system. The result is used by an optimization algorithm to update the defect structure to be incorporated in the FEM forward problem for the next iteration. Since the mentioned model based inverse algorithm normally consumes a lot of computational resources, the number of iterations plays an important role in the determination of the total response convergence time. Consequently, different optimization algorithms have been applied and their performances are compared. In this work by incorporating an efficient forward model and using the stochastic and deterministic optimization algorithms for defect updating we have investigated their performance on the inversion of the SQUID NDE signal and also their ability to defect reconstruction in the noisy environment.
In this paper a simple method for defect area detection in the subsurface layer of materials was presented. The method uses active infrared thermography. A statistical detectivity ratio was introduced for a quantitati...
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In this paper a simple method for defect area detection in the subsurface layer of materials was presented. The method uses active infrared thermography. A statistical detectivity ratio was introduced for a quantitative characterization of areas containing defects. The described algorithm of defect area detection was tested for a material with a low thermal diffusivity. The results of experimental and simulation investigations are presented. It was stated that the statistical detectivity ratio can be used to detect regions of defect presence, even for the non-uniformly heated surfaces.
This paper describes an image sensing method and defect detection algorithm applied for a newly developed mask inspection system, the MC-2000, for 256Mbit and 1Gbit DRAM masks. The MC-2000, which utilizes i-line wavel...
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ISBN:
(纸本)0819425168
This paper describes an image sensing method and defect detection algorithm applied for a newly developed mask inspection system, the MC-2000, for 256Mbit and 1Gbit DRAM masks. The MC-2000, which utilizes i-line wavelength optics, is designed for less than 0.2 mu m defectdetection capability. An image sensing system employing a TDI (Time Delay Integration) CCD image sensor is used for i-line image acquisition with an 80Mpixel/sec data rate. defectdetection is done by comparing sensor image data with CAD data, Here we utilized our original differential comparison method which has very high sensitivity for defectdetection.
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