检索范围:
排序: 展示方式:
Tomographic diagnosis of defects in hydraulic concrete structure
ZHAO Mingjie, XU Xibin
《结构与土木工程前沿(英文)》 2008年 第2卷 第3期 页码 226-232 doi: 10.1007/s11709-008-0027-5
关键词: satisfactory processing orientation tomographic diagnosis orientation perpendicular
Mohammad SALAVATI, Arvin MOJAHEDIN, Ali Hossein Nezhad SHIRAZI
《结构与土木工程前沿(英文)》 2020年 第14卷 第3期 页码 623-631 doi: 10.1007/s11709-020-0616-5
关键词: hexagonal boron-nitride mechanical properties crack notch point defects molecular dynamics
Automated classification of civil structure defects based on convolutional neural network
Pierclaudio SAVINO, Francesco TONDOLO
《结构与土木工程前沿(英文)》 2021年 第15卷 第2期 页码 305-317 doi: 10.1007/s11709-021-0725-9
关键词: concrete structure infrastructures visual inspection convolutional neural network artificial intelligence
《化学科学与工程前沿(英文)》 2023年 第17卷 第11期 页码 1755-1764 doi: 10.1007/s11705-023-2318-8
关键词: oxygen evolution reaction porous carbon nanosheets Co nanoparticles edge-induced topological defects Zn–air batteries
Thermal reffusivity: uncovering phonon behavior, structural defects, and domain size
Yangsu XIE, Bowen ZHU, Jing LIU, Zaoli XU, Xinwei WANG
《能源前沿(英文)》 2018年 第12卷 第1期 页码 143-157 doi: 10.1007/s11708-018-0520-z
关键词: thermal reffusivity theory phonon behavior structure defects structural thermal domain (STD) size 2D material amorphous material
Determining casting defects in near-net shape casting aluminum parts by computed tomography
Jiehua LI, Bernd OBERDORFER, Daniel HABE, Peter SCHUMACHER
《机械工程前沿(英文)》 2018年 第13卷 第1期 页码 48-52 doi: 10.1007/s11465-018-0493-y
Three types of near-net shape casting aluminum parts were investigated by computed tomography to determine casting defects and evaluate quality. The first, second, and third parts were produced by low-pressure die casting (Al-12Si-0.8Cu-0.5Fe-0.9Mg-0.7Ni-0.2Zn alloy), die casting (A356, Al-7Si-0.3Mg), and semi-solid casting (A356, Al-7Si-0.3Mg), respectively. Unlike die casting (second part), low-pressure die casting (first part) significantly reduced the formation of casting defects (i.e., porosity) due to its smooth filling and solidification under pressure. No significant casting defect was observed in the third part, and this absence of defects indicates that semi-solid casting could produce high-quality near-net shape casting aluminum parts. Moreover, casting defects were mostly distributed along the eutectic grain boundaries. This finding reveals that refinement of eutectic grains is necessary to optimize the distribution of casting defects and reduce their size. This investigation demonstrated that computed tomography is an efficient method to determine casting defects in near-net shape casting aluminum parts.
关键词: near-net shape casting aluminum parts casting defects low pressure die casting die casting semi-solid casting computed tomography
Detection of solder bump defects on a flip chip using vibration analysis
Junchao LIU, Tielin SHI, Qi XIA, Guanglan LIAO
《机械工程前沿(英文)》 2012年 第7卷 第1期 页码 29-37 doi: 10.1007/s11465-012-0314-7
Flip chips are widely used in microelectronics packaging owing to the high demand of integration in IC fabrication. Solder bump defects on flip chips are difficult to detect, because the solder bumps are obscured by the chip and substrate. In this paper a nondestructive detection method combining ultrasonic excitation with vibration analysis is presented for detecting missing solder bumps, which is a typical defect in flip chip packaging. The flip chip analytical model is revised by considering the influence of spring mass on mechanical energy of the system. This revised model is then applied to estimate the flip chip resonance frequencies. We use an integrated signal generator and power amplifier together with an air-coupled ultrasonic transducer to excite the flip chips. The vibrations are measured by a laser scanning vibrometer to detect the resonance frequencies. A sensitivity coefficient is proposed to select the sensitive resonance frequency order for defect detection. Finite element simulation is also implemented for further investigation. The results of analytical computation, experiment, and simulation prove the efficacy of the revised flip chip analytical model and verify the effectiveness of this detection method. Therefore, it may provide a guide for the improvement and innovation of the flip chip on-line inspection systems.
关键词: flip chip defect detection ultrasonic excitation vibration analysis
Diagnosis of sewer pipe defects on image recognition of multi-features and support vector machine in
Xiangyang Ye, Jian’e Zuo, Ruohan Li, Yajiao Wang, Lili Gan, Zhonghan Yu, Xiaoqing Hu
《环境科学与工程前沿(英文)》 2019年 第13卷 第2期 doi: 10.1007/s11783-019-1102-y
An image-recognition-based diagnosis system of pipe defect types was established. 1043 practical pipe images were gathered by CCTV robot in a southern Chinese city. The overall accuracy of the system is 84% and the highest accuracy is 99.3%. The accuracy shows positive correlation to the number of training samples.
关键词: Sewer pipe defects Defect diagnosing Image recognition Multi-features extraction Support vector machine
《化学科学与工程前沿(英文)》 2023年 第17卷 第1期 页码 93-101 doi: 10.1007/s11705-022-2175-x
关键词: g-C3N4 nitrogen defect sulfur doping photodegradation plasma
Loss of liver kinase B1 causes planar polarity defects in cochlear hair cells in mice
null
《医学前沿(英文)》 2016年 第10卷 第4期 页码 481-489 doi: 10.1007/s11684-016-0494-3
The tumor suppressor gene liver kinase B1 (LKB1), also called STK11, encodes a serine/threonine kinase. LKB1 plays crucial roles in cell differentiation, proliferation, and polarity. In this study, LKB1 conditional knockout mice (LKB1Pax2 CKO mice) were generated using Pax2-Cre mice to investigate the function of LKB1 in inner ear hair cells during early embryonic period. LKB1Pax2 CKO mice died perinatally. Immunofluorescence and scanning electron microscopy revealed that stereociliary bundles in LKB1Pax2 CKO mice were clustered and misoriented, respectively. Moreover, ectopic distribution of kinocilium bundles resulting from abnormal migration of kinocilium was observed in the mutant mice. The orientation of stereociliary bundles and the migration of kinocilia are critical indicators of planar cell polarity (PCP) of hair cells. LKB1 deficiency in LKB1Pax2 CKO mice thus disrupted hair cell planar polarity during embryonic development. Our results suggest that LKB1 is required in PCP formation in cochlear hair cells in mice.
关键词: LKB1 stereociliary bundles kinocilium planar cell polarity hearing mice
STRENGTHENING NON-POINT SOURCE POLLUTION CONTROL TO PROMOTE AGRICULTURAL GREEN DEVELOPMENT
《农业科学与工程前沿(英文)》 2023年 第10卷 第4期 页码 503-509 doi: 10.15302/J-FASE-2023528
STRENGTHENING NON-POINT SOURCE POLLUTION CONTROL TO PROMOTE AGRICULTURAL GREEN DEVELOPMENT
关键词: GREEN AGRICULTURAL PROMOTE POLLUTION SOURCE DEVELOPMENT POINT STRENGTHENING CONTROL
Wei Xiong, Susu Zhou, Zeyong Zhao, Fang Hao, Zhihui Cai, Pingle Liu, Hailiang Zhang, Hean Luo
《化学科学与工程前沿(英文)》 2021年 第15卷 第4期 页码 998-1007 doi: 10.1007/s11705-020-1994-x
关键词: nitrogen and phosphorus doping non-noble nickel catalyst aromatic compounds hydrogenation
M. NAZEMIZADEH, H. N. RAHIMI, K. AMINI KHOIY
《机械工程前沿(英文)》 2012年 第7卷 第1期 页码 23-28 doi: 10.1007/s11465-012-0304-9
This paper presents an optimal control strategy for optimal trajectory planning of mobile robots by considering nonlinear dynamic model and nonholonomic constraints of the system. The nonholonomic constraints of the system are introduced by a nonintegrable set of differential equations which represent kinematic restriction on the motion. The Lagrange’s principle is employed to derive the nonlinear equations of the system. Then, the optimal path planning of the mobile robot is formulated as an optimal control problem. To set up the problem, the nonlinear equations of the system are assumed as constraints, and a minimum energy objective function is defined. To solve the problem, an indirect solution of the optimal control method is employed, and conditions of the optimality derived as a set of coupled nonlinear differential equations. The optimality equations are solved numerically, and various simulations are performed for a nonholonomic mobile robot to illustrate effectiveness of the proposed method.
关键词: mobile robot trajectory planning nonlinear dynamic optimal control
屠海令
《中国工程科学》 2000年 第2卷 第1期 页码 7-17
随着超大规模集成电路设计线宽向深亚微米级(<0.5μm)和亚四分之一微米级(<0.25μm)发展,对半导体硅片及其它硅基材料的质量要求越来越高,研究上述材料中各种杂质的行为,控制缺陷类型及数量,提高晶体完整性,降低表面污染和采用缺陷工程的方法改善材料质量显得尤为重要。文章阐述了深亚微米级和亚四分之一微米级集成电路用大直径硅材料中铁、铜金属和氧、氢、氮非金属杂质元素的行为,点缺陷及其衍生缺陷的本质与控制方法,硅片表面形貌、表面污染与检测方法的研究热点。同时还介绍了外延硅、锗硅及绝缘体上硅(SOI)等硅基材料的特性、制备及工艺技术发展趋势,展望了跨世纪期间硅及硅基材料产业发展的技术经济前景。
《机械工程前沿(英文)》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0686-2
关键词: autonomous excavation unmanned electric shovel point cloud excavation trajectory planning
标题 作者 时间 类型 操作
Mechanical responses of pristine and defective hexagonal boron-nitride nanosheets: A molecular dynamics investigation
Mohammad SALAVATI, Arvin MOJAHEDIN, Ali Hossein Nezhad SHIRAZI
期刊论文
Automated classification of civil structure defects based on convolutional neural network
Pierclaudio SAVINO, Francesco TONDOLO
期刊论文
“Charging” the cigarette butt: heteroatomic porous carbon nanosheets with edge-induced topological defects
期刊论文
Thermal reffusivity: uncovering phonon behavior, structural defects, and domain size
Yangsu XIE, Bowen ZHU, Jing LIU, Zaoli XU, Xinwei WANG
期刊论文
Determining casting defects in near-net shape casting aluminum parts by computed tomography
Jiehua LI, Bernd OBERDORFER, Daniel HABE, Peter SCHUMACHER
期刊论文
Detection of solder bump defects on a flip chip using vibration analysis
Junchao LIU, Tielin SHI, Qi XIA, Guanglan LIAO
期刊论文
Diagnosis of sewer pipe defects on image recognition of multi-features and support vector machine in
Xiangyang Ye, Jian’e Zuo, Ruohan Li, Yajiao Wang, Lili Gan, Zhonghan Yu, Xiaoqing Hu
期刊论文
Tuning nitrogen defects and doping sulfur in carbon nitride for enhanced visible light photocatalytic
期刊论文
Highly uniform Ni particles with phosphorus and adjacent defects catalyze 1,5-dinitronaphthalene hydrogenation
Wei Xiong, Susu Zhou, Zeyong Zhao, Fang Hao, Zhihui Cai, Pingle Liu, Hailiang Zhang, Hean Luo
期刊论文
Trajectory planning of mobile robots using indirect solution of optimal control method in generalized point-to-point
M. NAZEMIZADEH, H. N. RAHIMI, K. AMINI KHOIY
期刊论文