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Visible defects detection based on UAV-based inspection in large-scale photovoltaic systems

IET RENEWABLE POWER GENERATION 2017年第10期11卷 1234-1244页

作者： Li, Xiaoxia Yang, Qiang Chen, Zhebo Luo, Xuejing Yan, Wenjun Zhejiang Univ Coll Elect Engn Hangzhou 310027 Zhejiang Peoples R China Zhejiang Univ Taizhou Inst Taizhou Zhejiang Peoples R China

The asset assessment and condition monitoring of large-scale photovoltaic (PV) systems spanning over a large geographical area has imposed urgent challenges and demands for novel and efficient inspection paradigm. In this study, an automatic UAV-based inspection system is presented and implemented for asset assessment and defect detection for large-scale PV systems. Two typical visible defects of PV modules, snail trails and dust shading, are characterised and the defect detection through image processing algorithms based on first order derivative of Gaussian function and feature matching is carried out for the aerial PV module images captured by visible light cameras. The functionality of the developed unmanned aerial vehicle (UAV)-based inspection system can be easily extended with more advanced fault detection algorithms and different forms of sensing devices (e.g. infrared thermal camera) for specialised inspection tasks. Such UAV-based imaging can carry out a variety of inspection and condition monitoring tasks in PV systems spanning over a large geographical area in an autonomous or supervised fashion with significantly promoted efficiency in comparison with conventional methods.

关键词： photovoltaic power systems inspection condition monitoring Gaussian processes image matching cameras image sensors autonomous aerial vehicles fault diagnosis power generation faults power engineering computing visible defect detection large-scale photovoltaic system asset assessment condition monitoring automatic UAV-based inspection system large scale PV system snail trail dust shading image processing algorithm Gaussian function feature matching aerial PV module visible light camera unmanned aerial vehicle advanced fault detection algorithm infrared thermal camera

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Sources of variation in Affymetrix microarray experiments

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BMC BIOINFORMATICS 2005年第1期6卷 1-11页

作者： Zakharkin, SO Kim, K Mehta, T Chen, L Barnes, S Scheirer, KE Parrish, RS Allison, DB Page, GP Univ Alabama Birmingham Sect Stat Genet Birmingham AL 35294 USA Univ Alabama Birmingham Dept Pharmacol Birmingham AL 35294 USA Univ Alabama Birmingham Dept Toxicol Birmingham AL 35294 USA Univ Alabama Birmingham Heflin Ctr Human Genet Birmingham AL 35294 USA Univ Louisville Dept Bioinformat & Biostat Louisville KY 40292 USA

Background: A typical microarray experiment has many sources of variation which can be attributed to biological and technical causes. Identifying sources of variation and assessing their magnitude, among other factors, are important for optimal experimental design. The objectives of this study were: (1) to estimate relative magnitudes of different sources of variation and (2) to evaluate agreement between biological and technical replicates. Results: We performed a microarray experiment using a total of 24 Affymetrix GeneChip (R) arrays. The study included 4th mammary gland samples from eight 21-day-old Sprague Dawley CD female rats exposed to genistein (soy isoflavone). RNA samples from each rat were split to assess variation arising at labeling and hybridization steps. A general linear model was used to estimate variance components. Pearson correlations were computed to evaluate agreement between technical and biological replicates. Conclusion: The greatest source of variation was biological variation, followed by residual error, and finally variation due to labeling when *.cel files were processed with dChip and RMA image processing algorithms. When MAS 5.0 or GCRMA-EB were used, the greatest source of variation was residual error, followed by biology and labeling. Correlations between technical replicates were consistently higher than between biological replicates.

关键词： Genistein Residual Error Microarray Experiment Affymetrix GeneChip image processing algorithm

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Non-destructive inspection of aircraft composite materials using triple IR imaging

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IFAC-PapersOnLine 2016年第28期49卷 291-296页

作者： Moustakidis, S. Anagnostis, A. Karlsson, P. Hrissagis, K. City University of London London United Kingdom IRETETH Institute for Research and Technology Thessaly CERTH Centre for Research & Technology Hellas Thessaloniki Greece

The wide use of composite materials in a number of industrial sectors has necessitated the development of new nondestructive inspection techniques for both manufacturing quality assurance and in-service damage testing. This paper discusses the development of a new holistic inspection system for aircraft composite materials that is composed of three thermographic cameras (operating at different wavelengths such as Near-infrared, Mid-Wave and Long-Wave) placed on the head of a robotic arm. Different setups were investigated in order to achieve optimal settings for a variety of influencing parameters including camera distance from the surface under investigation, excitation source type and power. Experiments were also conducted to define the effectiveness of each thermographic camera towards a variety of defect types. Advanced image processing algorithms were further developed and deployed to enhance the inspection capabilities of the three cameras and improve the interpretation of the collected thermal images. Future work on validating fusion and machine learning tools, their integration as well as on-site inspections has been planned. © 2016

关键词： Nondestructive examination Aircraft materials Cameras Composite materials Data handling Data processing Fighter aircraft image enhancement Infrared devices Inspection Learning systems Materials testing Quality assurance Thermography (imaging) Thermography (temperature measurement) Aircraft inspections Excitation sources image processing algorithm Influencing parameters Manufacturing quality Non destructive inspection On site inspection Thermographic cameras

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Stochastic algorithm for approximating soft morphological operators

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OPTICAL ENGINEERING 2001年第12期40卷 2746-2752页

作者： Zmuda, MA Miami Univ Dept Comp Sci & Syst Anal Oxford OH 45056 USA

A technique that approximates the output of the soft morphological operators is described. The soft operators can be viewed as a voting process across neighborhoods defined by the structuring element. Instead of processing all votes across a neighborhood, this approximation technique randomly samples elements in the neighborhood and uses these values as inputs to a two-state finite state machine, where the state of the machine corresponds to the output at a given pixel. When properly designed, the machines sample a small fraction of the neighborhood, obtain output that is 91 to 100% accurate at each pixel, and is one to two orders of magnitude faster than conventional algorithms. Experiments on binary textures and digits confirm the theoretical results. (C) 2001 Society of Photo-Optical Instrumentation Engineers.

关键词： mathematical morphology image processing algorithm

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A method for detection of randomly placed objects for robotic handling

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CIRP JOURNAL OF MANUFACTURING SCIENCE AND TECHNOLOGY 2016年 14卷 20-27页

作者： Tsarouchi, Panagiota Matthaiakis, Stereos-Alexandros Michalos, George Makris, Sotiris Chryssolouris, George Univ Patras Dept Mech Engn & Aeronaut Lab Mfg Syst & Automat Patras 26500 Greece

The image based systems still have open issues in order to meet the latest manufacturing requirements for simplicity, low cost as well as the limited maintenance requirements. In this direction, there is a method proposed for the recognition of 3D randomly placed objects for eventual robotic handling. The method includes a 2D vision system and is combined with data from computer-aided design (CAD) files for the generation of 3D coordinates. It is generic and can be used for the identification of multiple randomly placed objects. The method has been implemented in a software tool using MATLAB and has been applied to a consumer goods case for the recognition of shaver handles. (C) 2016 The Authors. This is an open access article under the CC BY-NC-ND license (hup://***/by-787791/4.01).

关键词： Object recognition image processing algorithm Robot Sensor Measurement

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Reflective scanning imaging based on a fast terahertz photodetector

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OPTICS COMMUNICATIONS 2018年 427卷 170-174页

作者： Qiu, Fucheng Tan, Zhiyong Fu, Zhanglong Wan, Wenjian Li, Mengqi Wang, Chang Cao, Juncheng Chinese Acad Sci Shanghai Inst Microsyst & Informat Technol Key Lab Terahertz Solid State Technol 865 Changning Rd Shanghai 200050 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

The fast detection of terahertz radiation is recognized as a key technology of terahertz imaging systems. We realize a terahertz imaging system employing a terahertz quantum-well photodetector (QWP) and a terahertz quantum cascade laser (QCL). The detector can rapidly detect the 4.3THz light generated from a pulsed electrically-pump terahertz QCL, which is used as the terahertz source of the imaging system. The object is placed on a rotary scanning platform to realize fast scanning. A practical detection method of the terahertz pulse signal is employed to extract the amplitude information from the terahertz signal and improve the signal-to-noise ratio (SNR) of the system. The electrical and optical performances of the fast terahertz QWP are characterized, and the results show that the terahertz QWP can completely meet the fast detection requirement of the terahertz imaging system. The terahertz images of some invisible objects are obtained with a high contrast within 5 s. The imaging system owns a resolution of 0.3 mm and a circular imaging region with a diameter of 100 mm. An image processing algorithm is applied in this system to solve the noise problem and improve the quality of the images. The imaging results indicate that terahertz QWP has a good application prospect in nondestructive inspection applications and the research of the fast physical or chemistry process.

关键词： Terahertz quantum-well photodetectors Fast imaging system Pulse signal detection method Invisible objects image processing algorithm

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Blinking supervision in a working environment

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JOURNAL OF BIOMEDICAL OPTICS 2016年第2期21卷 25005页

作者： Morcego, Bernardo Argiles, Marc Cabrerizo, Marc Cardona, Genis Perez, Ramon Perez-Cabre, Elisabet Gispets, Joan Univ Politecn Cataluna Adv Control Syst Res Grp Rambla Sant Nebridi 10 Terrassa 08222 Spain Univ Politecn Cataluna Dept Opt & Optometry Sch Opt & Optometry C Violinista Vellsola 37 Terrassa 08222 Spain

The health of the ocular surface requires blinks of the eye to be frequent in order to provide moisture and to renew the tear film. However, blinking frequency has been shown to decrease in certain conditions such as when subjects are conducting tasks with high cognitive and visual demands. These conditions are becoming more common as people work or spend their leisure time in front of video display terminals. Supervision of blinking frequency in such environments is possible, thanks to the availability of computer-integrated cameras. Therefore, the aim of the present study is to develop an algorithm for the detection of eye blinks and to test it, in a number of videos captured, while subjects are conducting a variety of tasks in front of the computer. The sensitivity of the algorithm for blink detection was found to be of 87.54% (range 30% to 100%), with a mean false-positive rate of 0.19% (range 0% to 1.7%), depending on the illumination conditions during which the image was captured and other computer-user spatial configurations. The current automatic process is based on a partly modified pre-existing eye detection and image processing algorithms and consists of four stages that are aimed at eye detection, eye tracking, iris detection and segmentation, and iris height/width ratio assessment. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： automatic eye blink detection blinking frequency image processing algorithm computer vision syndrome video display terminal dry eye webcam

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Spatiotemporal characterization of 3D fracture behavior of carbon-fiber-reinforced polymer composites

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COMPOSITE STRUCTURES 2018年 203卷 30-37页

作者： Pei, Shenli Wang, Kaifeng Li, Yang Zeng, Danielle Su, Xuming Li, Jingjing Yang, Hui Xiao, Xianghui Penn State Univ Dept Ind & Mfg Engn State Coll PA 16802 USA Ford Motor Co Res & Innovat Ctr Dearborn MI 48124 USA Argonne Natl Lab Adv Photon Source Argonne IL 60439 USA

This study proposed a spatiotemporal algorithm to quantitatively characterize the in-situ 3D fracture behavior of carbon-fiber-reinforced polymer (CFRP) composites at microscale. In-situ micro X-ray computed tomography (mu XCT) integrated with a tensile stage was applied to capture the 3D fracture evolution of the CFRP composites, where the initiation and propagation of fracture features (e.g., fiber tip-end crack and fiber/matrix debonding) were identified. After the reconstruction of the 3D material microstructure, the proposed spatiotemporal algorithm thereafter extracted the fracture features by employing multiple image processing techniques for quantitative analysis. A similar distribution of the 3D strain obtained from the volumetric digital image correlation demonstrated the feasibility of the developed spatiotemporal algorithm. Moreover, this algorithm provided in-depth and quantitative analysis of fracture features, which provided insights into the microscale failure mechanism and thus shed light on the improvement of failure criteria for CFRP composites with complex microstructures.

关键词： Carbon fiber reinforced polymer composite Micro X-ray computed tomography Fracture feature image processing algorithm

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Experimental study on water-exit of cylinder

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OCEAN ENGINEERING 2024年 293卷

作者： Yun, Honglu Liu, Qingbo Zeng, Zheng Lian, Lian Shanghai Jiao Tong Univ Sch Oceanog Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ State Key Lab Ocean Engn Shanghai 200240 Peoples R China

In this paper, the hydrodynamic characteristics of the cylinder water-exit are studied by high-speed camera experiments. The characteristics of cylindrical motion trajectory, velocity and acceleration are analyzed by image processing algorithm. The emission voltage (i.e. initial velocity) and emission depth are important influencing factors. Based on different emission voltage and depth, the hydrodynamic coefficient is compared and analyzed. The results show that the new research method has good adaptability to the experimental study of cylindrical water-exit. The emission voltage directly affects the initial velocity of the cylinder, which in turn affects the force changes during the water exit process. The increase in emission depth exacerbates the uncertainty of the moment when the cylinder exits the water, thereby affecting the changes in the wake and motion stability during the cylinder water exit process.

关键词： Water-exit Hydrodynamic characteristics image processing algorithm

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Novel Method of Calculation of Magnetic Resonance Imaging Perfusion and Comparison of Single versus Double Barrel Superficial Temporal Artery-Middle Cerebral Artery Bypass for Revascularisation in Moya Moya Disease

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WORLD NEUROSURGERY 2024年 181卷 E516-E523页

作者： Manjunath, Niveditha Dhanakshirur, Rohan Raju Joshi, Siddharth Reddy, Nikhila Gunna Raheja, Amol Sebastian, Leve Joseph Devrajan Garg, Ajay Kalra, Prem Kumar Suri, Ashish All India Inst Med Sci Dept Neurosurg Bhubaneswar India Indian Inst Technol Amarnath & Shashi Khosla Sch Informat Technol Delhi India All India Inst Med Sci Dept Neuroimaging & Intervent Neuroradiol New Delhi India Indian Inst Technol Dept Comp Sci & Engn New Delhi India

OBJECTIVE: Moyamoya disease (MMD) is characterized by supraclinoid internal carotid artery narrowing causing cerebral parenchyma to starve. Direct and indirect revascularisation techniques are the treatment norm. We provide a clinicoradiological comparison of single and double barrel superficial temporal artery to middle cerebral artery (STA-MCA) bypass for MMD. The perfusion in cerebral hemispheres and vessel density in digital subtraction angiography (DSA) have been evaluated using novel algorithms. METHODS: DSA, arterial spin labeling magnetic resonance imaging methods and Suzuki, Matsushima, Angiographic Outcome Score scales were used to quantify perfusion parameters;modified Rankin Score was used for clinical evaluation. A novel image processing algorithm was designed to perform analysis of arterial spin labeling sequences and compare perfusion. Vessel density was calculated using connected component analysis on thresholded DSA images. RESULTS: Fifty-four hemispheres with MMD underwent STA-MCA bypass 42(77.8%) single barrel and 12 (22.2%) double barrel. Clinical outcome-modified Rankin Score was significant with P < 0.001 in single barrel and P = 0.001 in double barrel groups. The overall Angiographic Outcome Score showed improvement postoperatively (P = 0.032). Perfusion analysis was performed in 20 hemispheres (13 single barrel;7 double barrel). MCA territories showed significant improvement in single barrel (2.72%, P = 0.0294) and double barrel groups (12.89%, P = 0.025). Vessel density calculated in MCA territory, showed an overall postoperative improvement (P = 1.75 3 10e8). CONCLUSION: Double barrel STA-MCA bypass clinically as well as radiologically improves perfusion in the ACA as well as MCA territories in MMD. The novel image processing algorithm is an accurate, objective tool to evaluate perfusion in magnetic resonance images and vessel density in DSA images of MMD.

关键词： Double barrel bypass image processing algorithm Moya Moya disease Perfusion analysis Revascularization Single barrel bypass

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