Inspired by the coarse-to-fine visual perception process of human vision system,a new approach based on Gaussian multi-scale space for defect detection of industrial products was proposed.By selecting different scale ...Inspired by the coarse-to-fine visual perception process of human vision system,a new approach based on Gaussian multi-scale space for defect detection of industrial products was proposed.By selecting different scale parameters of the Gaussian kernel,the multi-scale representation of the original image data could be obtained and used to constitute the multi- variate image,in which each channel could represent a perceptual observation of the original image from different scales.The Multivariate Image Analysis (MIA) techniques were used to extract defect features information.The MIA combined Principal Component Analysis (PCA) to obtain the principal component scores of the multivariate test image.The Q-statistic image, derived from the residuals after the extraction of the first principal component score and noise,could be used to efficiently reveal the surface defects with an appropriate threshold value decided by training images.Experimental results show that the proposed method performs better than the gray histogram-based method.It has less sensitivity to the inhomogeneous of illumination,and has more robustness and reliability of defect detection with lower pseudo reject rate.展开更多
For high strength interstitial free （IF） steel containing P element, the salt and pepper （SP） defects exist on the strip surface and could not be eliminated effectively by optimizing the hot rolling process, such ...For high strength interstitial free （IF） steel containing P element, the salt and pepper （SP） defects exist on the strip surface and could not be eliminated effectively by optimizing the hot rolling process, such as temperature and cooling water. The combination effect of Si and P on the characteristic of tertiary scale has been studied comprehensively by scanning electron microscopy （SEM） and electron probe microanalysis （EPMA）, and the concept is proposed firstly that Si and P are of combination effect which can be utilized to eliminate the SP defect. The results show that the SP defects were induced by the rolled-in scale during finish rolling. P can be enriched at the interface between substrate and tertiary scale, which is easy to decrease the adhesion of tertiary scale. However, Si enrichment at the interface between substrate and tertiary scale can increase the adhesion. The SP defects can be eliminated completely, which is attributed to the accompanying enrichment of Si and P.展开更多
The isothermal local loading forming technology provides a feasible way to form Ti-alloy large-scale rib-web components in aerospace and aviation fields.However,the local loading process forming limit is restricted by...The isothermal local loading forming technology provides a feasible way to form Ti-alloy large-scale rib-web components in aerospace and aviation fields.However,the local loading process forming limit is restricted by forming defects in the transitional region.In this work,the feasibility of controlling forming defects and improving the process forming limit by adjusting die parameters is explored through finite element（FE） simulation.It is found that the common cavum and folding defects in the transitional region are significantly influenced by the fillet radii of left rib and middle rib,respectively.The cavum and folding defects can be effectively controlled by increasing the fillet radii of left rib and middle rib,respectively.The process forming limits considering forming defects in the transitional region are determined by the stepwise searching method under various die parameters.Moreover,the relationship between the process forming limit and die parameters is developed through the response surface methodology（RSM）.The developed RSM models suggest that increasing the fillet radii of left and middle ribs is effective to improve the process forming limit during local loading forming of rib-web components.The results will provide technical basis for the design of die parameters and the reduction amount,which is of great importance to control forming defects and improve the process forming limit in local loading forming of Ti-alloy large-scale rib-web components.展开更多
A multiple-time-scale algorithm is developed to numerically simulate certain structural components in civil structures where local defects inevitably exist. Spatially, the size of local defects is relatively small com...A multiple-time-scale algorithm is developed to numerically simulate certain structural components in civil structures where local defects inevitably exist. Spatially, the size of local defects is relatively small compared to the structural scale. Different length scales should be adopted considering the efficiency and computational cost. In the principle of physics, different length scales are stipulated to correspond to different time scales. This concept lays the foundation of the framework for this multiple-time-scale algorithm. A multiple-time-scale algorithm, which involves different time steps for different regions, while enforcing the compatibility of displacement, force and stress fields across the interface, is proposed. Furthermore, a defected beam component is studied as a numerical sample. The structural component is divided into two regions： a coarse one and a fine one; a micro-defect exists in the fine region and the finite element sizes of the two regions are diametrically different. Correspondingly, two different time steps are adopted. With dynamic load applied to the beam, stress and displacement distribution of the defected beam is investigated from the global and local perspectives. The numerical sample reflects that the proposed algorithm is physically rational and computationally efficient in the potential damage simulation of civil structures.展开更多
AIM: To show the efficacy of reconstruction and rehabilitation of large acquired maxillofacial defects due to tumor resections and firearm injuries. METHODS: The study group comprised of 16 patients(10 men and 6 women...AIM: To show the efficacy of reconstruction and rehabilitation of large acquired maxillofacial defects due to tumor resections and firearm injuries. METHODS: The study group comprised of 16 patients(10 men and 6 women) who were operated on because of their maxillofacial defects under local and general anesthesia between June 2007 and June 2011. Prosthetic treatment with the aid of dental implants was performed for all of the patients. Eight patients received an implant supported fixed prosthesis; six patients received implant supported overdentures and two patients received both. Patients were followed up postoperatively for 1 to 4 years. Implant success and survival rates were recorded. Panoramic radiographs were taken preoperatively, immediately after surgery, immediately after loading and at every recall session. Peri-implant and prosthetic complications were recorded. Subjects were asked to grade their oral health satisfaction after treatment according to 100 mm visual analog scale(VAS) and the oral health related quality oflife of the patients was measured with the short-form Oral Health Impact Profile. RESULTS: Five implants(3 in the mandible, 2 in the maxilla) in five patients were lost, while the other 53 survived, which brings an overall survival rate of 91.37% on the implant basis, but 68.75% on patient basis. All the failed implants were lost before abutment connection and were therefore regarded as early failures. For all failed implants, new implants were placed after a 2 mo period and the planning was maintained. The mean marginal bone loss(MBL) was 1.4 mm on the mesial side and 1.6 mm on the distal side of the implants. Five of the implants showed MBL > 2 mm(mean MBL = 2.3 mm) but less than 1/2 of the implant bodies and therefore were regarded as not successful but surviving implants. The VAS General Comfort mean score was 85.07, the VAS Speech mean score was 75.25 and the VAS Esthetics mean score was 82.74. No patient reported low scores(score lower than 50) of satisfaction in any of the evaluated factors. The mean of OHIP-14 scores was 5.5. CONCLUSION: Although further follow up and larger case numbers will give more information about the success of dental implants as a treatment modality in maxillofacial defects patients, the actual results are encouraging and can be recommended for similar cases.展开更多
基金supported in part by the Natural Science Foundation of China (NSFC) (Grant No:50875240).
文摘Inspired by the coarse-to-fine visual perception process of human vision system,a new approach based on Gaussian multi-scale space for defect detection of industrial products was proposed.By selecting different scale parameters of the Gaussian kernel,the multi-scale representation of the original image data could be obtained and used to constitute the multi- variate image,in which each channel could represent a perceptual observation of the original image from different scales.The Multivariate Image Analysis (MIA) techniques were used to extract defect features information.The MIA combined Principal Component Analysis (PCA) to obtain the principal component scores of the multivariate test image.The Q-statistic image, derived from the residuals after the extraction of the first principal component score and noise,could be used to efficiently reveal the surface defects with an appropriate threshold value decided by training images.Experimental results show that the proposed method performs better than the gray histogram-based method.It has less sensitivity to the inhomogeneous of illumination,and has more robustness and reliability of defect detection with lower pseudo reject rate.
文摘For high strength interstitial free （IF） steel containing P element, the salt and pepper （SP） defects exist on the strip surface and could not be eliminated effectively by optimizing the hot rolling process, such as temperature and cooling water. The combination effect of Si and P on the characteristic of tertiary scale has been studied comprehensively by scanning electron microscopy （SEM） and electron probe microanalysis （EPMA）, and the concept is proposed firstly that Si and P are of combination effect which can be utilized to eliminate the SP defect. The results show that the SP defects were induced by the rolled-in scale during finish rolling. P can be enriched at the interface between substrate and tertiary scale, which is easy to decrease the adhesion of tertiary scale. However, Si enrichment at the interface between substrate and tertiary scale can increase the adhesion. The SP defects can be eliminated completely, which is attributed to the accompanying enrichment of Si and P.
基金the support of the National Natural Science Foundation of China(Nos.51605388,51675433)111 Project(B08040)+2 种基金the Research Fund of the State Key Laboratory of Solidification Processing(NWPU)in China(Grant No.131-QP-2015)the Fundamental Research Funds for the Central Universitiesthe Open Research Fund of State Key Laboratory of Materials Processing and Die&Mold Technology at Huazhong University of Science and Technology
文摘The isothermal local loading forming technology provides a feasible way to form Ti-alloy large-scale rib-web components in aerospace and aviation fields.However,the local loading process forming limit is restricted by forming defects in the transitional region.In this work,the feasibility of controlling forming defects and improving the process forming limit by adjusting die parameters is explored through finite element（FE） simulation.It is found that the common cavum and folding defects in the transitional region are significantly influenced by the fillet radii of left rib and middle rib,respectively.The cavum and folding defects can be effectively controlled by increasing the fillet radii of left rib and middle rib,respectively.The process forming limits considering forming defects in the transitional region are determined by the stepwise searching method under various die parameters.Moreover,the relationship between the process forming limit and die parameters is developed through the response surface methodology（RSM）.The developed RSM models suggest that increasing the fillet radii of left and middle ribs is effective to improve the process forming limit during local loading forming of rib-web components.The results will provide technical basis for the design of die parameters and the reduction amount,which is of great importance to control forming defects and improve the process forming limit in local loading forming of Ti-alloy large-scale rib-web components.
基金supports from NSFC(No.11302078)China Postdoctoral Science Foundation(No.2013M531139)Shanghai Postdoctoral Sustentation Fund(No.12R21412000)
文摘A multiple-time-scale algorithm is developed to numerically simulate certain structural components in civil structures where local defects inevitably exist. Spatially, the size of local defects is relatively small compared to the structural scale. Different length scales should be adopted considering the efficiency and computational cost. In the principle of physics, different length scales are stipulated to correspond to different time scales. This concept lays the foundation of the framework for this multiple-time-scale algorithm. A multiple-time-scale algorithm, which involves different time steps for different regions, while enforcing the compatibility of displacement, force and stress fields across the interface, is proposed. Furthermore, a defected beam component is studied as a numerical sample. The structural component is divided into two regions： a coarse one and a fine one; a micro-defect exists in the fine region and the finite element sizes of the two regions are diametrically different. Correspondingly, two different time steps are adopted. With dynamic load applied to the beam, stress and displacement distribution of the defected beam is investigated from the global and local perspectives. The numerical sample reflects that the proposed algorithm is physically rational and computationally efficient in the potential damage simulation of civil structures.
文摘AIM: To show the efficacy of reconstruction and rehabilitation of large acquired maxillofacial defects due to tumor resections and firearm injuries. METHODS: The study group comprised of 16 patients(10 men and 6 women) who were operated on because of their maxillofacial defects under local and general anesthesia between June 2007 and June 2011. Prosthetic treatment with the aid of dental implants was performed for all of the patients. Eight patients received an implant supported fixed prosthesis; six patients received implant supported overdentures and two patients received both. Patients were followed up postoperatively for 1 to 4 years. Implant success and survival rates were recorded. Panoramic radiographs were taken preoperatively, immediately after surgery, immediately after loading and at every recall session. Peri-implant and prosthetic complications were recorded. Subjects were asked to grade their oral health satisfaction after treatment according to 100 mm visual analog scale(VAS) and the oral health related quality oflife of the patients was measured with the short-form Oral Health Impact Profile. RESULTS: Five implants(3 in the mandible, 2 in the maxilla) in five patients were lost, while the other 53 survived, which brings an overall survival rate of 91.37% on the implant basis, but 68.75% on patient basis. All the failed implants were lost before abutment connection and were therefore regarded as early failures. For all failed implants, new implants were placed after a 2 mo period and the planning was maintained. The mean marginal bone loss(MBL) was 1.4 mm on the mesial side and 1.6 mm on the distal side of the implants. Five of the implants showed MBL > 2 mm(mean MBL = 2.3 mm) but less than 1/2 of the implant bodies and therefore were regarded as not successful but surviving implants. The VAS General Comfort mean score was 85.07, the VAS Speech mean score was 75.25 and the VAS Esthetics mean score was 82.74. No patient reported low scores(score lower than 50) of satisfaction in any of the evaluated factors. The mean of OHIP-14 scores was 5.5. CONCLUSION: Although further follow up and larger case numbers will give more information about the success of dental implants as a treatment modality in maxillofacial defects patients, the actual results are encouraging and can be recommended for similar cases.
