The band structures of flexural waves in a phononic crystal thin plate with straight, bending or branching linear defects are theoretically investigated using the supercell technique based on the improved plane wave e...The band structures of flexural waves in a phononic crystal thin plate with straight, bending or branching linear defects are theoretically investigated using the supercell technique based on the improved plane wave expansion method. We show the existence of an absolute band gap of the perfect phononic crystal and linear defect modes inside the gap caused by localization of flexural waves at or near the defects. The displacement distributions show that flexural waves can transmit well along the straight linear defect created by removing one row of cylinders from the perfect phononic crystals for almost all the frequencies falling in the band gap, which indicates that this structure can act as a high efficiency waveguide. However, for bending or branching linear defects, there exist both guided and localized modes, and therefore the phononic crystals could be served as waveguides or filters.展开更多
In the industrial production of expanded thermoplastic polyurethane (E-TPU) midsoles, the surface defects still rely on manual inspection at present, and the eligibility criteria are uneven. Therefore, this paper prop...In the industrial production of expanded thermoplastic polyurethane (E-TPU) midsoles, the surface defects still rely on manual inspection at present, and the eligibility criteria are uneven. Therefore, this paper proposes an E-TPU midsole surface defect detection method based on machine vision to achieve automatic detection and defect classification. The proposed method is divided into three parts: image preprocessing, block defect detection, and linear defect detection. Image preprocessing uses RGB three channel self-inspection to identify scorch and color pollution. Block defect detection uses superpixel segmentation and background prior mining to determine holes, impurities, and dirt. Linear defect detection uses Gabor filter and Hough transform to detect indentation and convex marks. After image preprocessing, block defect detection and linear defect detection are simultaneously performed by parallel computing. The false positive rate (FPR) of the proposed method in this paper is 8.3%, the false negatives rate (FNR) of the hole is 4.7%, the FNR of indentation is 2.1%, and the running time does not exceed 1.6 s. The test results show that this method can quickly and accurately detect various defects in the E-TPU midsole.展开更多
We proposed a detection method for wood defects based on linear discriminant analysis (LDA) and the use of compressed sensor images. Wood surface images were captured, using a camera Oscar F810C IRF camera, and then t...We proposed a detection method for wood defects based on linear discriminant analysis (LDA) and the use of compressed sensor images. Wood surface images were captured, using a camera Oscar F810C IRF camera, and then the image segmentation was performed, and the defect features were extracted from wood board images. To reduce the processing time, LDA algorithm was used to integrate these features and reduce their dimensions. Features after fusion were used to construct a data dictionary and a compressed sensor was designed to recognize the wood defects types. Of the three major defect types, 50 images live knots, dead knots, and cracks were used to test the effects of this method. The average time for feature fusion and classification was 0.446 ms with the classification accuracy of 94%.展开更多
This paper considers a model regarding the products with finite life which allows defective items in reproduction and causes a small amount of decay. The market demand is assumed to be level dependent linear type. The...This paper considers a model regarding the products with finite life which allows defective items in reproduction and causes a small amount of decay. The market demand is assumed to be level dependent linear type. The model has also considered the constant production rate which stops after a desired level of inventories and that is the highest level of it. Due to the market demand, defective item and product’s decay, the inventory reduces to the zero level where again the production cycle starts. With a numerical search procedure</span><span style="font-size:12px;font-family:Verdana;">,</span><span style="font-size:12px;font-family:Verdana;"> the proof of the proposed model has been shown. The objective of the proposed model is to find out the total optimum inventory cost, optimum ordering cost and optimum ordering cycle.展开更多
Trace is the important composition structure of printed circuit board,w hich connects the devices,it is also the module that taking up the highest proportion,thus,it is the major testing target of quality assurance. T...Trace is the important composition structure of printed circuit board,w hich connects the devices,it is also the module that taking up the highest proportion,thus,it is the major testing target of quality assurance. The sunken defects proposed in this paper is a w idth abnormity defect on the FPC trace,w hich w ould cause the latent open circuit defect and affect the electrical function of circuit. The problem of flexible deformation and w idth difference make the FPC trace detection harder. Therefore,this paper proposed a detection scheme combined w ith linear masks and circle distribution characteristic. Firstly,this scheme preprocessed the acquired FPC image,divided the trace into several sub-regions and obtained the line w idth values of each trace transverse section. Then the line w idth sequences w ere searched w ith the linear difference template of gray scale. Thus,the sunken defects alternative positions w ere located. Lastly,the circle distribution characteristic is defined to identify the real defect areas from the alternative regions acquired from the previous step. Thus,the detection of sunken defects on the FPC trace w as accomplished.The algorithm w as tested in the self-built image database,w hich show s the better detection performance than the other typical algorithms.展开更多
基金Project (Nos 10632020 and 90715006) supported by the National Natural Science Foundation of China
文摘The band structures of flexural waves in a phononic crystal thin plate with straight, bending or branching linear defects are theoretically investigated using the supercell technique based on the improved plane wave expansion method. We show the existence of an absolute band gap of the perfect phononic crystal and linear defect modes inside the gap caused by localization of flexural waves at or near the defects. The displacement distributions show that flexural waves can transmit well along the straight linear defect created by removing one row of cylinders from the perfect phononic crystals for almost all the frequencies falling in the band gap, which indicates that this structure can act as a high efficiency waveguide. However, for bending or branching linear defects, there exist both guided and localized modes, and therefore the phononic crystals could be served as waveguides or filters.
文摘In the industrial production of expanded thermoplastic polyurethane (E-TPU) midsoles, the surface defects still rely on manual inspection at present, and the eligibility criteria are uneven. Therefore, this paper proposes an E-TPU midsole surface defect detection method based on machine vision to achieve automatic detection and defect classification. The proposed method is divided into three parts: image preprocessing, block defect detection, and linear defect detection. Image preprocessing uses RGB three channel self-inspection to identify scorch and color pollution. Block defect detection uses superpixel segmentation and background prior mining to determine holes, impurities, and dirt. Linear defect detection uses Gabor filter and Hough transform to detect indentation and convex marks. After image preprocessing, block defect detection and linear defect detection are simultaneously performed by parallel computing. The false positive rate (FPR) of the proposed method in this paper is 8.3%, the false negatives rate (FNR) of the hole is 4.7%, the FNR of indentation is 2.1%, and the running time does not exceed 1.6 s. The test results show that this method can quickly and accurately detect various defects in the E-TPU midsole.
基金supported by the State Forestry Administration‘‘948’’projects(2015-4-52)Fundamental Research Funds for the Central Universities(2572016BB05)+1 种基金Natural Science Foundation of Heilongjiang Province(C2015054)Heilongjiang Postdoctoral Research Fund(LBH-Q14014)
文摘We proposed a detection method for wood defects based on linear discriminant analysis (LDA) and the use of compressed sensor images. Wood surface images were captured, using a camera Oscar F810C IRF camera, and then the image segmentation was performed, and the defect features were extracted from wood board images. To reduce the processing time, LDA algorithm was used to integrate these features and reduce their dimensions. Features after fusion were used to construct a data dictionary and a compressed sensor was designed to recognize the wood defects types. Of the three major defect types, 50 images live knots, dead knots, and cracks were used to test the effects of this method. The average time for feature fusion and classification was 0.446 ms with the classification accuracy of 94%.
文摘This paper considers a model regarding the products with finite life which allows defective items in reproduction and causes a small amount of decay. The market demand is assumed to be level dependent linear type. The model has also considered the constant production rate which stops after a desired level of inventories and that is the highest level of it. Due to the market demand, defective item and product’s decay, the inventory reduces to the zero level where again the production cycle starts. With a numerical search procedure</span><span style="font-size:12px;font-family:Verdana;">,</span><span style="font-size:12px;font-family:Verdana;"> the proof of the proposed model has been shown. The objective of the proposed model is to find out the total optimum inventory cost, optimum ordering cost and optimum ordering cycle.
文摘Trace is the important composition structure of printed circuit board,w hich connects the devices,it is also the module that taking up the highest proportion,thus,it is the major testing target of quality assurance. The sunken defects proposed in this paper is a w idth abnormity defect on the FPC trace,w hich w ould cause the latent open circuit defect and affect the electrical function of circuit. The problem of flexible deformation and w idth difference make the FPC trace detection harder. Therefore,this paper proposed a detection scheme combined w ith linear masks and circle distribution characteristic. Firstly,this scheme preprocessed the acquired FPC image,divided the trace into several sub-regions and obtained the line w idth values of each trace transverse section. Then the line w idth sequences w ere searched w ith the linear difference template of gray scale. Thus,the sunken defects alternative positions w ere located. Lastly,the circle distribution characteristic is defined to identify the real defect areas from the alternative regions acquired from the previous step. Thus,the detection of sunken defects on the FPC trace w as accomplished.The algorithm w as tested in the self-built image database,w hich show s the better detection performance than the other typical algorithms.
