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DSN-BR-Based Online Inspection Method and Application for Surface Defects of Pharmaceutical Products in Aluminum-Plastic Blister Packages
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作者 Mingzhou Liu Yu Gong +2 位作者 Xiaoqiao Wang Conghu Liu Jing Hu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第4期194-214,共21页
Ensuring high product quality is of paramount importance in pharmaceutical drug manufacturing,as it is subject to rigorous regulatory practices.This study presents a research focused on the development of an on-line d... Ensuring high product quality is of paramount importance in pharmaceutical drug manufacturing,as it is subject to rigorous regulatory practices.This study presents a research focused on the development of an on-line detection method and system for identifying surface defects in pharmaceutical products packaged in aluminum-plastic blisters.Firstly,the aluminum-plastic blister packages exhibit multi-scale features and inter-class indistinction.To address this,the deep semantic network with boundary refinement(DSN-BR)model is proposed,which leverages semantic segmentation domain knowledge,to accurately segment the defects in pixel level.Additionally,a specialized image acquisition module that minimizes the impact of ambient light is established,ensuring high-quality image capture.Finally,the image acquisition module,image detection module,and data management module are designed to construct a comprehensive online surface defect detection system.To validate the effectiveness of our approach,we employ a real dataset for instance verification on the implemented system.The experimental results substantiate the outstanding performance of the DSN-BR,achieving the mean intersection over union(MIoU)of 90.5%.Furthermore,the proposed system achieves an inference speed of up to 14.12 f/s,while attaining an F1-Score of 98.25%.These results demonstrate that the system meets the actual needs of the enterprise and provides theoretical and methodological support for intelligent inspection of product surface quality.By standardizing the control process of pharmaceutical manufacturing and improving the management capability of the manufacturing process,our approach holds significant market application prospects. 展开更多
关键词 surface defect detection system Deep learning Semantic segmentation Aluminum-plastic blister packages identification
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SAM Era:Can It Segment Any Industrial Surface Defects?
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作者 Kechen Song Wenqi Cui +2 位作者 Han Yu Xingjie Li Yunhui Yan 《Computers, Materials & Continua》 SCIE EI 2024年第3期3953-3969,共17页
Segment Anything Model(SAM)is a cutting-edge model that has shown impressive performance in general object segmentation.The birth of the segment anything is a groundbreaking step towards creating a universal intellige... Segment Anything Model(SAM)is a cutting-edge model that has shown impressive performance in general object segmentation.The birth of the segment anything is a groundbreaking step towards creating a universal intelligent model.Due to its superior performance in general object segmentation,it quickly gained attention and interest.This makes SAM particularly attractive in industrial surface defect segmentation,especially for complex industrial scenes with limited training data.However,its segmentation ability for specific industrial scenes remains unknown.Therefore,in this work,we select three representative and complex industrial surface defect detection scenarios,namely strip steel surface defects,tile surface defects,and rail surface defects,to evaluate the segmentation performance of SAM.Our results show that although SAM has great potential in general object segmentation,it cannot achieve satisfactory performance in complex industrial scenes.Our test results are available at:https://github.com/VDT-2048/SAM-IS. 展开更多
关键词 Segment anything SAM surface defect detection salient object detection
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Building surface defects by doping with transition metal on ultrafine TiO_2 to enhance the photocatalytic H_2 production activity 被引量:6
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作者 Qi‐Feng Liu Qian Zhang +2 位作者 Bing‐Rui Liu Shiyou Li Jing‐Jun Ma 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2018年第3期542-548,共7页
Inefficient charge separation and limited light absorption are two critical issues associated with high‐efficiency photocatalytic H2production using TiO2.Surface defects within a certain concentration range in photoc... Inefficient charge separation and limited light absorption are two critical issues associated with high‐efficiency photocatalytic H2production using TiO2.Surface defects within a certain concentration range in photocatalyst materials are beneficial for photocatalytic activity.In this study,surface defects(oxygen vacancies and metal cation replacement defects)were induced with a facile and effective approach by surface doping with low‐cost transition metals(Co,Ni,Cu,and Mn)on ultrafine TiO2.The obtained surface‐defective TiO2exhibited a3–4‐fold improved activity compared to that of the original ultrafine TiO2.In addition,a H2production rate of3.4μmol/h was obtained using visible light(λ>420nm)irradiation.The apparent quantum yield(AQY)at365nm reached36.9%over TiO2‐Cu,significantly more than the commercial P25TiO2.The enhancement of photocatalytic H2production activity can be attributed to improved rapid charge separation efficiency andexpanded light absorption window.This hydrothermal treatment with transition metal was proven to be a very facile and effective method for obtaining surface defects. 展开更多
关键词 Construction of surface defects Ultrafine TiO2 Low‐cost transition metal surface doping Photocatalytic H2 production
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Tuning the crystallite size of monoclinic ZrO_(2) to reveal critical roles of surface defects on m–ZrO_(2) catalyst for direct synthesis of isobutene from syngas 被引量:2
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作者 Xuemei Wu Minghui Tan +7 位作者 Bing Xu Shengying Zhao Qingxiang Ma Yingluo He Chunyang Zeng Guohui Yang Noritatsu Tsubaki Yisheng Tan 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2021年第7期211-219,共9页
The effects of crystallite size on the physicochemical properties and surface defects of pure monoclinic ZrO_(2) catalysts for isobutene synthesis were studied.We prepared a series of monoclinic ZrO_(2) catalysts with... The effects of crystallite size on the physicochemical properties and surface defects of pure monoclinic ZrO_(2) catalysts for isobutene synthesis were studied.We prepared a series of monoclinic ZrO_(2) catalysts with different crystallite size by changing calcination temperature and evaluated their catalytic performance for isobutene synthesis from syngas.ZrO_(2) with small crystalline size showed higher CO conversion and isobutene selectivity,while samples with large crystalline size preferred to form dimethyl ether(DME)instead of hydrocarbons,much less to isobutene.Oxygen defects(ODefects)analyzed by X-ray photoelectron spectroscopy(XPS)provided evidence that more ODefectsoccupied on the surface of ZrO_(2) catalysts with smaller crystalline size.Electron paramagnetic resonance(EPR)and ultraviolet–visible diffuse reflectance(UV–vis DRS)confirmed the presence of high concentration of surface defects and Zr3+on mZrO_(2)-5.9 sample,respectively.In situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS)analysis indicated that the adsorption strength of formed formate species on catalyst reduced as the crystalline size decreased.These results suggested that surface defects were responsible for CO activation and further influenced the adsorption strength of surface species,and thus the products distribution changed.This study provides an in-depth insight for active sites regulation of ZrO_(2) catalyst in CO hydrogenation reaction. 展开更多
关键词 SYNGAS ISOBUTENE ZrO_(2)catalyst Crystallite size surface defects
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Creation of surface defects on carbon nanofibers by steam treatment 被引量:1
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作者 Zhengfeng Shao Min Pang +2 位作者 Wei Xia Martin Muhler Changhai Liang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2013年第5期804-810,共7页
A direct strategy for the creation of defects on carbon nanofibers (CNFs) has been developed by steam treatment.Nitrogen physisorption,XRD,Raman spectra,SEM and TEM analyses proved the existence of the new defects on ... A direct strategy for the creation of defects on carbon nanofibers (CNFs) has been developed by steam treatment.Nitrogen physisorption,XRD,Raman spectra,SEM and TEM analyses proved the existence of the new defects on CNFs.BET surface area of CNFs after steam treatment was enhanced from 20 to 378 m2/g.Pd catalysts supported on CNFs were also prepared by colloidal deposition method.The different activity of Pd/CNFs catalysts in the partial hydrogenation of phenylacetylene further demonstrated the diverse surfaces of CNFs could be formed by steam treatment. 展开更多
关键词 carbon nanofibers surface defects steam treatment PALLADIUM
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Impact of Methanol Photomediated Surface Defects on Photocatalytic H2 Production Over Pt/TiO2 被引量:1
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作者 Zhi Jiang Rongjie Qi +3 位作者 Zhengwen Huang Wenfeng Shanggguan Roong Jien Wong Adam Lee 《Energy & Environmental Materials》 2020年第2期202-208,共7页
Co-catalysts play a critical role in enhancing the efficiency of inorganic semiconductor photocatalysts;however,synthetic approaches to tailoring cocatalyst properties are rarely the focus of research efforts.A photom... Co-catalysts play a critical role in enhancing the efficiency of inorganic semiconductor photocatalysts;however,synthetic approaches to tailoring cocatalyst properties are rarely the focus of research efforts.A photomediated route to control the dispersion and oxidation state of a platinum(Pt)cocatalyst through defect generation in the P25 titania photocatalyst substrate is reported.Titania photoirradiation in the presence of methanol induces longlived surface defects which subsequently promote the photodeposition of highly dispersed(2.2±0.8 nm)and heavily reduced Pt nanoparticles on exposure to H2 PtCl6.The optimal methanol concentration of 20 vol%produces the highest density of metallic Pt nanoparticles.Photocatalytic activity for water splitting and associated hydrogen(H2)production under UV irradiation mirrors the methanol concentration employed during the P25 photoirradiation pretreatment and resulting Pt loading resulting in a common mass-normalized H2 productivity of 3800±130 mmol gpt-1 h-1.Photomediated surface defects(arising in the presence of a methanol hole scavenger)provide electron traps that regulate subsequent photodeposition of a Pt co-catalyst over P25,offering a facile route to tune photocatalytic efficiency. 展开更多
关键词 METHANOL PLATINUM surface defects TITANIUM
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Analytical Modeling and Mechanism Analysis of Time-Varying Excitation for Surface Defects in Rolling Element Bearings 被引量:1
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作者 Laihao Yang Yu Sun +2 位作者 Ruobin Sun Lixia Gao Xuefeng Chen 《Journal of Dynamics, Monitoring and Diagnostics》 2023年第2期89-101,共13页
Surface defects,including dents,spalls,and cracks,for rolling element bearings are the most common faults in rotating machinery.The accurate model for the time-varying excitation is the basis for the vibration mechani... Surface defects,including dents,spalls,and cracks,for rolling element bearings are the most common faults in rotating machinery.The accurate model for the time-varying excitation is the basis for the vibration mechanism analysis and fault feature extraction.However,in conventional investigations,this issue is not well and fully addressed from the perspective of theoretical analysis and physical derivation.In this study,an improved analytical model for time-varying displacement excitations(TVDEs)caused by surface defects is theoretically formulated.First and foremost,the physical mechanism for the effect of defect sizes on the physical process of rolling element-defect interaction is revealed.According to the physical interaction mechanism between the rolling element and different types of defects,the relationship between time-varying displacement pulse and defect sizes is further analytically derived.With the obtained time-varying displacement pulse,the dynamic model for the deep groove bearings considering the internal excitation caused by the surface defect is established.The nonlinear vibration responses and fault features induced by surface defects are analyzed using the proposed TVDE model.The results suggest that the presence of surface defects may result in the occurrence of the dual-impulse phenomenon,which can serve as indexes for surface-defect fault diagnosis. 展开更多
关键词 analytical model rolling bearings surface defects time-varying excitation vibration mechanism
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Contribution of Surface Defects to the Interface Conductivity of SrTiO_3/LaAlO_3
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作者 关丽 谈凤雪 +3 位作者 贾国奇 申光明 刘保亭 李旭 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第8期105-108,共4页
Based on the first-principles method, the structural stability and the contribution of point defects such as O, Sr or Ti vacancies on two-dimensional electron gas of n- and p-type LaAlO3/SrTiO3 interfaces are investig... Based on the first-principles method, the structural stability and the contribution of point defects such as O, Sr or Ti vacancies on two-dimensional electron gas of n- and p-type LaAlO3/SrTiO3 interfaces are investigated. The results show that O vacancies at p-type interfaces have much lower formation energies, and Sr or Ti vacancies at n-type interfaces are more stable than the ones at p-type interfaces under O-rich conditions. The calculated densities of states indicate that O vacancies act as donors and give a significant compensation to hole carriers, resulting in insulating behavior at p-type interfaces. In contrast, Sr or Ti vacancies tend to trap electrons and behave as acceptors. Sr vacancies are the most stable defects at high oxygen partial pressures, and the Sr vacancies rather than Ti vacancies are responsible for the insulator-metal transition of n-type interface. The calculated results can be helpful to understand the tuned electronic properties of LaAlO3 /SrTiO3 heterointerfaces. 展开更多
关键词 of LAO in on STO Contribution of surface defects to the Interface Conductivity of SrTiO3/LaAlO3 for
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AN EFFICIENT LABELLING ALGORITHM FOR WOODPANELS SURFACE DEFECTS
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作者 王克奇 《Journal of Northeast Forestry University》 SCIE CAS CSCD 1995年第4期54-57,共4页
This paper describes an efficient approach for labeling images using a combination of pipeline (Datacube) and (general purpose computer) processing. The output of the algorithm is coordinate list of labeled object pix... This paper describes an efficient approach for labeling images using a combination of pipeline (Datacube) and (general purpose computer) processing. The output of the algorithm is coordinate list of labeled object pixels that facilitates further high level operations. It is an efficient labeling algorithm for a automatic classification of surface defects on wood boards. 展开更多
关键词 Image modeling Patter recognition WOOD surface defects
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Effects of Surface Defects on Adsorption of CO and Methyl Groups on Rutile TiO_(2)(110)
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作者 Deng-fang Tang Xiao Chen +1 位作者 Qing Guo Wen-shao Yang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2021年第3期249-255,I0013,I0014,I0047,共10页
The interaction of reactants with catalysts has always been an important subject for catalytic reactions.As a promising catalyst with versatile applications,titania has been intensively studied for decades.In this wor... The interaction of reactants with catalysts has always been an important subject for catalytic reactions.As a promising catalyst with versatile applications,titania has been intensively studied for decades.In this work we have investigated the role of bridge bonded oxygen vacancy(O_(v))in methyl groups and carbon monoxide(CO)adsorption on rutile TiO_(2)(110)(R-TiO_(2)(110))with the temperature programmed desorption technique.The results show a clear different tendency of the desorption of methyl groups adsorbed on bridge bonded oxygen(O_(b)),and CO molecules on the five coordinate Ti^(4+)sites(Ti_(5c))as the Ovconcentration changes,suggesting that the surface defects may have crucial influence on the absorption of species on different sites of R-TiO_(2)(110). 展开更多
关键词 Temperature programmed desorption TiO_(2)(110) Bridge bonded oxygen vacancy Adsorption sites surface defects
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Surface defects in 4H-SiC homoepitaxial layers 被引量:3
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作者 Lixia Zhao 《Nanotechnology and Precision Engineering》 CAS CSCD 2020年第4期229-234,共6页
Although a high-quality homoepitaxial layer of 4H‑silicon carbide(4H-SiC)can be obtained on a 4°off-axis substrate using chemical vapor deposition,the reduction of defects is still a focus of research.In this stu... Although a high-quality homoepitaxial layer of 4H‑silicon carbide(4H-SiC)can be obtained on a 4°off-axis substrate using chemical vapor deposition,the reduction of defects is still a focus of research.In this study,several kinds of surface defects in the 4H-SiC homoepitaxial layer are systemically investigated,including triangles,carrots,surface pits,basal plane dislocations,and step bunching.Themorphologies and structures of surface defects are further discussed via optical microscopy and potassium hydroxide-based defect selective etching analysis.Through research and analysis,we found that the origin of surface defects in the 4H-SiC homoepitaxial layer can be attributed to two aspects:the propagation of substrate defects,such as scratches,dislocation,and inclusion,and improper process parameters during epitaxial growth,such as in-situ etch,C/Si ratio,and growth temperature.It is believed that the surface defects in the 4H-SiC homoepitaxial layer can be significantly decreased by precisely controlling the chemistry on the deposition surface during the growth process. 展开更多
关键词 4H silicon carbide surface defect Chemical vapor deposition REDUCTION
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Laser ultrasonic technique for surface defects detection of 6061 aluminum alloy 被引量:2
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作者 LI Hai-yang WEI Zhuang-zhuang PAN Qiang-Hua 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2019年第3期293-298,共6页
In order to estimate and detect the surface defect depth of metals, the transmission method of laser ultrasonic surface waves is used in this work. The laser ultrasonic detection platform taking use of thermoelastic m... In order to estimate and detect the surface defect depth of metals, the transmission method of laser ultrasonic surface waves is used in this work. The laser ultrasonic detection platform taking use of thermoelastic mechanism as acoustic signal excitation method and interference receiver as acoustic signal receiver method was built, by which B-scan images of detected specimens with surface defects were collected to establish the relationship between the transmission coefficient and depth of the surface defect. Experimental results show that the amplitude of transmitted acoustic signal is related to the depth of surface defect. At last, a fitted curve of transmission coefficient using measured experimental data is obtained to estimate depth of surface defect on the 6061 aluminum alloy. Furthermore, a surface defect depth of 0.3 mm is estimated by the fitting curve with an estimated error of 16%. Therefore, a experimental method using the transmission method by laser ultrasonic is presented in this paper. 展开更多
关键词 laser ultrasonics transmission method surface defect depth detection
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A fast detection algorithm for ceramic ball surface defects based on fringe reflection 被引量:2
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作者 SUN Ying FU Lu-hua WANG Zhong 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2020年第1期28-37,共10页
A ceramic ball is a basic part widely used in precision bearings.There is no perfect testing equipment for ceramic ball surface defects at present.A fast visual detection algorithm for ceramic ball surface defects bas... A ceramic ball is a basic part widely used in precision bearings.There is no perfect testing equipment for ceramic ball surface defects at present.A fast visual detection algorithm for ceramic ball surface defects based on fringe reflection is designed.By means of image preprocessing,grayscale value accumulative differential positioning,edge detection,pixel-value row difference and template matching,the algorithm can locate feature points and judge whether the spherical surface has defects by the number of points.Taking black silicon nitride ceramic balls with a diameter of 6.35 mm as an example,the defect detection time for a single gray scale image is 0.78 s,and the detection limit is 16.5μm. 展开更多
关键词 ceramic ball surface defect fringe reflection visual detection algorithm
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Automated visual inspection of surface defects based on compound moment invariants and support vector machine 被引量:1
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作者 Zhang Xuewu Xu Lizhong +1 位作者 Ding Yanqiong Fan Xinnan 《High Technology Letters》 EI CAS 2012年第1期26-32,共7页
The traditional inspection methods are mostly based on manual inspection which is very likely to make erroneous judgments due to personal subjectivity or eye fatigue, and can't satisfy the accuracy. To overcome these... The traditional inspection methods are mostly based on manual inspection which is very likely to make erroneous judgments due to personal subjectivity or eye fatigue, and can't satisfy the accuracy. To overcome these difficulties, we develop a machine vision inspection system. We first compare several kinds of methods for feature extraction and classification, and then present a real-time automated visual inspection system for copper strips surface (CSS) defects based on compound moment invariants and support vector machine (SVM). The proposed method first processes images collected by hardware system, and then extracts feature characteristics based on grayscale characteristics and morphologic characteristics (Hu and Zernike compound moment invariants). Finally, we use SVM to classify the CSS defects. Furthermore, performance comparisons among SVM, back propagation (BP) and radial basis function (RBF) neural networks have been involved. Experimental results show that the proposed approach achieves an accuracy of 95.8% in detecting CSS defects. 展开更多
关键词 copper strips surface (CSS) defects compound invariant moments support vector machine(SVM) visual inspection system neural network
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Surface defects incorporated diamond machining of silicon
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作者 Neha Khatri Borad M Barkachary +3 位作者 B Muneeswaran Rajab Al-Sayegh Xichun Luo Saurav Goel 《International Journal of Extreme Manufacturing》 EI 2020年第4期57-73,共17页
This paper reports the performance enhancement benefits in diamond turning of the silicon wafer by incorporation of the surface defect machining(SDM)method.The hybrid micromachining methods usually require additional ... This paper reports the performance enhancement benefits in diamond turning of the silicon wafer by incorporation of the surface defect machining(SDM)method.The hybrid micromachining methods usually require additional hardware to leverage the added advantage of hybrid technologies such as laser heating,cryogenic cooling,electric pulse or ultrasonic elliptical vibration.The SDM method tested in this paper does not require any such additional baggage and is easy to implement in a sequential micro-machining mode.This paper made use of Raman spectroscopy data,average surface roughness data and imaging data of the cutting chips of silicon for drawing a comparison between conventional single-point diamond turning(SPDT)and SDM while incorporating surface defects in the(i)circumferential and(ii)radial directions.Complementary 3D finite element analysis(FEA)was performed to analyse the cutting forces and the evolution of residual stress on the machined wafer.It was found that the surface defects generated in the circumferential direction with an interspacing of 1 mm revealed the lowest average surface roughness(Ra)of 3.2 nm as opposed to 8 nm Ra obtained through conventional SPDT using the same cutting parameters.The observation of the Raman spectroscopy performed on the cutting chips showed remnants of phase transformation during the micromachining process in all cases.FEA was used to extract quantifiable information about the residual stress as well as the sub-surface integrity and it was discovered that the grooves made in the circumferential direction gave the best machining performance.The information being reported here is expected to provide an avalanche of opportunities in the SPDT area for low-cost machining solution for a range of other nominal hard,brittle materials such as SiC,ZnSe and GaAs as well as hard steels. 展开更多
关键词 surface defect machining SILICON finite element analysis surface roughness
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Surface Defects of Cold-Rolled Ti-IF Steel Sheets due to Non-Metallic Inclusions 被引量:8
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作者 CUI Heng1, WU Hua-jie1, YUE Feng1, WU Wei-shuang1, WANG Min1, BAO Yan-ping1, CHEN Bin2, JI Chen-xi2 (1. Engineering Research Institute, University of Science and Technology Beijing, Beijing 100083, China 2. Shougang Research Institute of Technology, Beijing 100043, China) 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2011年第S2期335-340,共6页
Surface defects of the cold-rolled sheets of Ti-IF steel were studied and analyzed. After analyzing surface defects of cold-rolled sheets, such as shelling defects, holes and sliver defects by SEM/EDS, a variety of in... Surface defects of the cold-rolled sheets of Ti-IF steel were studied and analyzed. After analyzing surface defects of cold-rolled sheets, such as shelling defects, holes and sliver defects by SEM/EDS, a variety of inclusions were found. In addition, the distribution of macro-inclusions in slabs was analyzed by MIDAS method. The results show the macroscopic inclusion bands of head slabs and normal slabs are in 1/8 slab thickness regions of both inner arc side and outer arc side. The formation process of the defects in the cold-rolled sheets was simulated with an experimental cold-rolling machine for comparison. The results show that there were three kinds of inclusions underneath the surface defects: Al2O3, SiO2 and particles from slag entrainment, which were the main reason for defect formation during cold rolling. 展开更多
关键词 Ti-IF steel cold-rolled sheet surface defects INCLUSION
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Molecular Dynamics Simulation of Tensile Deformation and Fracture of γ-TiAl with and without Surface Defects 被引量:10
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作者 H.N.Wu D.S.Xu +1 位作者 H.Wang R.Yang 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2016年第10期1033-1042,共10页
Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-TiAl single crystals.The r... Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-TiAl single crystals.The results indicate that brittle fracture occurs in perfect bulk; surfaces and edges will be detrimental to the strength of materials and provide dislocation nucleation site. The defects on surfaces and edges cause further weakening with various effects depending on defect type, size, position and orientation,while the edge dimples are the most influential. For γ-TiAl rods with surface dimples, dislocations nucleate from an edge of the rod when dimples are small, dimple dislocation nucleation occurs only when the dimples are larger than a strain rate dependent critical size. The dislocations nucleated upon [001]tension are super dislocations with Burger vectors 〈011] or 1/2 〈 112] containing four 1/6 〈 112 〉 partials. The effects of surface scratches are orientation and shape sensitive. Scratches parallel to the loading direction have little influence, while sharp ones perpendicular to the loading direction may cause crack and thus should be avoided. This simulation also shows that, any type of surface defect would lower strength,and cause crack in some cases. But some may facilitate dislocation nucleation and improve ductility of TiAl if well controlled. 展开更多
关键词 Intermetallic compounds Superdislocation Fracture surface defects Molecular dynamics
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Study on incident laser modulation using surface micro-defects on KH_2PO_4 crystal
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作者 陈明君 程健 +7 位作者 李明全 肖勇 曲遵世 王勇刚 刘杰 郑丽和 苏良碧 徐军 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第6期249-256,共8页
KH2PO4 crystal is a crucial optical component of inertial confinement fusion. Modulation of an incident laser by surface micro-defects will induce the growth of surface damage, which largely restricts the enhancement ... KH2PO4 crystal is a crucial optical component of inertial confinement fusion. Modulation of an incident laser by surface micro-defects will induce the growth of surface damage, which largely restricts the enhancement of the laser induced damage threshold. The modulation of an incident laser by using different kinds of surface defects are simulated by employing the three-dimensional finite-difference time-domain method. The results indicate that after the modulation of surface defects, the light intensity distribution inside the crystal is badly distorted, with the light intensity enhanced symmetrically. The relations between modulation properties and defect geometries (e.g., width, morphology, and depth of defects) are quite different for different defects. The modulation action is most obvious when the width of surface defects reaches 1.064 p-m. For defects with smooth morphology, such as spherical pits, the degree of modulation is the smallest and the light intensity distribution seems relatively uniform. The degree of modulation increases rapidly with the increase of the depth of surface defects and becomes stable when the depth reaches a critical value. The critical depth is 1.064 μm for cuboid pits and radial cracks, while for ellipsoidal pits the value depends on both the width and the length of the defects. 展开更多
关键词 KH2PO4 crystal surface defects modulation degree three-dimensional finite-differencetime-domain
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Numerical simulation of laser ultrasonic detection of the surface microdefects on laser powder bed fusion additive manufactured 316L stainless steel
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作者 Yang Liu Zhixin Peng +1 位作者 Sheng Liu Ping Hu 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2022年第6期451-458,共8页
A numerical model is presented in this article to investigate the interactions between laser generated ultrasonic and the microdefects(0.01 to 0.1 mm),which are on the surface of the laser powder bed fusion additive m... A numerical model is presented in this article to investigate the interactions between laser generated ultrasonic and the microdefects(0.01 to 0.1 mm),which are on the surface of the laser powder bed fusion additive manufactured 316L stainless steel.Firstly,the influence of the transient sound field and detection positions on Rayleigh wave signals are investigated.The interactions between the varied microdefects and the laser ultrasonic are studied.It is shown that arrival time of reflected Rayleigh(RR)waves wave is only related to the location of defects.The depth can be checked from the feature point Q,the displacement amplitude and time delay of converted transverse(RS)wave,while the width information can be evaluated from the RS wave time delay.With the aid of fitting curves,it is found to be linearly related.This simulation study provides a theoretical basis for quantitative detection of surface microdefects of additive manufactured 316L stainless steel components. 展开更多
关键词 Laser ultrasonic Numerical simulation Metal additive manufacturing surface defects
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Neutral and metallic vs.charged and semiconducting surface layer in acceptor doped CeO_(2)
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作者 Ilan Riess 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第4期795-802,共8页
The monomolecular surface layer of acceptor doped CeO_(2) may become neutral and metallic or charged and semiconducting.This is revealed in the theoretical analysis of the oxygen pressure dependence of the surface def... The monomolecular surface layer of acceptor doped CeO_(2) may become neutral and metallic or charged and semiconducting.This is revealed in the theoretical analysis of the oxygen pressure dependence of the surface defects concentration in acceptor doped ceria with two different dopant types and operated under different oxygen pressures.Recently published experimental data for highly reduced Sm0.2Ce0.8O1.9-x(SDC)containing a fixed valence dopant Sm3+are very different from those published for Pr0.1Ce0.9O_(2)-x(PCO) with the variable valence dopant Pr4+/Pr3+being reduced under milder conditions.The theoretical analysis of these experimental results fits very well the experimental results of SDC and PCO.It leads to the following predictions:the highly reduced surface of SDC is metallic and neutral,the metallic surface electron density of state is gs=0.9×10^(38)J-1·m^(-2)(1.4×1015eV^(-1)·cm^(-2)),the electron effective mass is meff,s=3.3me,and the phase diagram of the reduced surface has theα(fcc)structure as in the bulk.In PCO a double layer is predicted to be formed between the surface and the bulk with the surface being negatively charged and semiconducting.The surface of PCO maintains high Pr^(3+) defect concentration as well as relative high oxygen vacancy concentration at oxygen pressures higher than in the bulk.The reasons for the difference between a metallic and semiconducting surface layer of acceptor doped CeO_(2) are reviewed,as well as the key theoretical considerations applied in coping with this problem.For that we make use of the experimental data and theoretical analysis available for acceptor doped ceria. 展开更多
关键词 CeO_(2) surface defects metallic surface oxide reduction Sm doped CeO_(2) Pr doped CeO_(2)
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