Inspection Angle Research Articles

Low-dose energy-resolved X-ray computed tomography using a filter-changing two-dimensional transXend detector

ABSTRACT A novel detector system ‘transXend’ detector, which measured X-rays as electric current and output the energy distribution of X-rays after analysis, has been developed by the authors. With computed tomography (CT) by using the transXend detector, CT image was given in the absolute value of linear attenuation coefficient as a function of X-ray energy and the effective atomic number distribution in a subject was obtained. For the X-ray CT of a large object such as a human body, the development of a two-dimensional transXend detector is necessary and the authors proposed a filter-changing transXend detector previously. The exposure dose to the subject, however, increased due to the multiple inspections with various X-ray spectra tailored by each filter. To reduce the exposure dose, a method is proposed to synchronize filter changes with changes of the inspection angle of the subject. With this method, the exposure dose can be reduced nearly 50% compared to a conventional electric current measurement CT.

MVGCN: Multi-View Graph Convolutional Neural Network for Surface Defect Identification Using Three-Dimensional Point Cloud

Abstract Surface defect identification is a crucial task in many manufacturing systems, including automotive, aircraft, steel rolling, and precast concrete. Although image-based surface defect identification methods have been proposed, these methods usually have two limitations: images may lose partial information, such as depths of surface defects, and their precision is vulnerable to many factors, such as the inspection angle, light, color, noise, etc. Given that a three-dimensional (3D) point cloud can precisely represent the multidimensional structure of surface defects, we aim to detect and classify surface defects using a 3D point cloud. This has two major challenges: (i) the defects are often sparsely distributed over the surface, which makes their features prone to be hidden by the normal surface and (ii) different permutations and transformations of 3D point cloud may represent the same surface, so the proposed model needs to be permutation and transformation invariant. In this paper, a two-step surface defect identification approach is developed to investigate the defects’ patterns in 3D point cloud data. The proposed approach consists of an unsupervised method for defect detection and a multi-view deep learning model for defect classification, which can keep track of the features from both defective and non-defective regions. We prove that the proposed approach is invariant to different permutations and transformations. Two case studies are conducted for defect identification on the surfaces of synthetic aircraft fuselage and the real precast concrete specimen, respectively. The results show that our approach receives the best defect detection and classification accuracy compared with other benchmark methods.

Distributed Small-Step Path Planning and Detection Method for Post-earthquake Robot to Inspect and Evaluate Building Damage.

Post-earthquake robots can be used extensively to inspect and evaluate building damage for safety assessment. However, the surrounding environment and path for such robots are complex and unstable with unexpected obstacles. Thus, path planning for such robot is crucial to guarantee satisfactory inspection and evaluation while approaching the ideal position. To achieve this goal, we proposed a distributed small-step path planning method using modified reinforcement learning (MRL). Limited distance and 12 directions were gridly refined for the robot to move around. The small moving step ensures the path planning to be optimal in a neighboring safe region. The MRL updates the direction and adjusts the path to avoid unknown disturbances. After finding the best inspection angle, the camera on the robot can capture the picture clearly, thereby improving the detection capability. Furthermore, the corner point detection method of buildings was improved using the Harris algorithm to enhance the detection accuracy. An experimental simulation platform was established to verify the designed robot, path planning method, and overall detection performance. Based on the proposed evaluation index, the post-earthquake building damage was inspected with high accuracy of up to 98%, i.e., 20% higher than traditional unplanned detection. The proposed robot can be used to explore unknown environments, especially in hazardous conditions unsuitable for humans.

Age features of the lower nasal passage according to endoscopy in children

To study the anatomical features of the lower nasal passage in children in the age aspect by analyzing the results of endoscopic examination of the nasal cavity. The study included 377 children who did not have otorhinolaryngological and ophthalmological pathologies, as well as congenital anomalies in the architectonics of the nose. The distribution into 4 groups, depending on age, was carried out according to the main provisions of the classification of childhood periods by N.P. Gundobin: the first group - children under 1 year old - 80 (21.2%), the second group - from 1 year to 3 years inclusive - 97 (25.7%), the third group - from 4 to 6 years inclusive - 96 (25.5%), the fourth group (control) - from 7 years and older - 104 (27.6%). All patients underwent endoscopic examination of the nasal cavity using rigid endoscopes with a viewing angle of 0 and 30 degrees, 2.7 mm in diameter, and a fibroscope with an inspection angle of 0 degrees, 2.5 mm in diameter. The data on the features of the development of the lower nasal passage in children were obtained. Changes in such anatomical parameters as the diameter of the lower nasal passage, the location of the distal opening of the nasolacrimal canal and the lower turbinate itself in the nasal cavity are presented. Highlighted the peak age periods of the development of the lower nasal passage in children: the first 6 months, 3-4 years and 7-8 years of a child's life. It was revealed that in children under 6 months of age, the middle turbinates are closely adjacent to the lower ones, which, as a rule, are large, tightly pressed to the bottom of the nasal cavity, and therefore the lower nasal passages are extremely weakly expressed. With growing up, their diameter grows from less than 2.0 mm to an average value of 2.90±0.03 mm, while after 7 years, fully formed volumetric lower nasal passages are already noted. In newborns and children of the first year of life, the mouth of the nasolacrimal duct is as close as possible to the bottom of the nasal cavity, and during growing up it gradually shifts upward (finally settling in the area of the fornix of the lower nasal passage or in the area of transition of the fornix to the lateral wall of the lower nasal passage) and posterior to the anterior the end of the inferior turbinate (up to 4 years old is at a distance of less than 1.0 cm, from 4 to 6 years old - 1.0 cm, from 7 years old - 1.14±0.01 cm). The data obtained as a result of the study are necessary for an otorhinolaryngologist and an ophthalmologist for a full understanding of the processes of development and course, as well as methods of treating various combined rhinological and dacryological pathologies in children.

Laser array spots thermography for detection of cracks in curved structures

The laser array spot thermography (LAST) is a fully non-contact and non-destructive method for the inspection of surface cracks with high efficiency. In this study, the detection capability of this method for the inspection of surface cracks in structures with curved surfaces is experimentally studied. The influence of the inspection angle on the crack imaging results is also investigated. The experiment results show that cracks in surface of the pipes with different dimeters can be detected and imaged by LAST.

Effectiveness of phased array focused ultrasound and active infrared thermography methods as a nondestructive testing of Ni-WC coating adhesion

ABSTRACTThe substrate/coating adhesion is a crucial parameter conditioning the quality of coating and its durability in service. For this reason, an inspection of the coating integrity, in particular, the presence of adhesion defects will be of great importance. The adhesion inspection is usually ensured by destructive methods, such as traction, interfacial indentation, four-point bending, testing scratch, etc. However, it is currently hampered by the absence of a satisfactory non-destructive method. Among the non-destructive testing technologies widely used in the industrial field, there are X-ray diffraction, ultrasonic inspection, and infrared thermography. In this paper, two methods are investigated: ultrasonic inspection, which becoming more efficient, especially with the emergence of phased array systems that allow to investigate different inspection angles and focusing depths, and the active infrared thermography. Experiments were performed on metallic coatings deposited on a mild steel substrate. Coatings were containing artificial defects (flat bottom holes with different diameters) at the interface and others were exempts of defects. Longitudinal waves with specific delay laws were generated through a phased array contact transducer (5 MHz of central frequency). Experimental results show that the ultrasonic method allows detecting and sizing defects with a diameter of 1 mm located in thick coatings.

Analysis of the configuration and the location of thermographic equipment for the inspection in photovoltaic systems

The infrared (IR) thermography is a non-destructive technique (NDT) which is used to carry out maintenance quickly and easily in photovoltaic (PV) systems. IR imaging with thermographic cameras under steady state conditions is a usual method for quality control of PV modules and plants in operation. For the proper IR inspection which determines the severity or the importance of the detected findings, it is necessary to consider different aspects of the configuration and the location of the thermographic equipment which allow reducing measuring errors. This paper considers some elements which contribute to the accurate configuration of the thermographic equipment. The influence of the reflected apparent temperature in outdoor IR inspections is analysed and it is proposed a simple method for obtaining it. Besides, the importance of the emissivity in IR thermography is analysed. For that, the value of the emissivity in PV modules of various types both front and rear shape is determined experimentally. It is also studied the proper location of the thermographic equipment in order to minimize reflections of the sun and the sky. For this objective, it is studied the ideal and minimum height of inspection according to the layout of the PV system. In a particular case, it is also analysed the influence of the horizontal angle of thermographic inspection and the reflected radiation.

Quantitative Assessment of CFRP-concrete Cylinders Using Synthetic Aperture Radar Images

ABSTRACTA feature extraction algorithm is proposed to quantitatively assess the condition of intact and damaged carbon fiber reinforced polymer (CFRP)-wrapped concrete cylinders using synthetic aperture radar (SAR) images. The proposed algorithm converts SAR images into a simplified representation, based on the shape, size, and amplitude of SAR images. In this approach, the shape of scatterers in a SAR image is characterized by average Gaussian curvature (K), area ratio (R), and SAR amplitude (I), and is represented by a K-R-I curve. SAR images of intact and damaged CFRP-wrapped concrete cylinders were generated by a stripmap SAR imaging radar system (10.5 GHz) at various inspection angles (0°, 15°, 25°, 30°, 45°, and 60°). From our experimental result, it is found that the K-R-I representation of SAR images is capable of distinguishing damaged SAR images from intact ones at different inspection angles. Quantitative dissimilarity between the K-R-I curves of intact and damaged specimens is assessed by coefficient of correlation and compared with the signal-to-noise ratio (SNR) of SAR images. It is found that the dissimilarity of K-R-I curves is closely related to the SNR of SAR images, demonstrating the feasibility and potential of the proposed K-R-I representation.

가압기 노즐 이종금속 용접부의 구조적 오버레이 용접부에 대한 위상배열 초음파기법의 현장 적용

Abstract Weld overlay was first used in power plants in the US in the early 1980s as an interim method of repairing the welds of flawed piping joints. Weld overlaid piping joints in nuclear power plants must be examined periodically using ultrasonic examination technology. Portable phased array ultrasonic technology has recently become available. Currently, the application of preemptive weld overlays as a mitigation technique and/as a method to improve the examination surface condition for more complex configurations is becoming more common. These complex geometries may require several focused conventional transducers for adequate inspection of the overlay, the original weld, and the base material. Alternatively, Phased array ultrasonic probes can be used to generate several inspection angles simultaneously at various focal depths to provide better and faster coverage than that possible by conventional methods. Thus, this technology can increase the speed of examinations, save costs, and reduce radiation exposure. In this paper, we explain the general sequence of the inspection of weld overlay and the results of signal analysis for some PAUT (phased array ultrasonic testing) signals detected in on-site inspections.

횡파 위상배열 초음파 탐촉자 설계 및 성능 평가

일반적으로 위상배열 초음파검사 기법을 이용한 배관 용접부검사에서는 높은 검사 각도를 효과적으로 발생하기 위하여 ��지를 사용하게 된다. 그러나 용접부 또는 접근이 제한된 부위에 대한 검사는 위상 배열 초음파 탐촉자에 ��지를 부착하게 되면 ��지의 전단 길이로 인하여 검사체적을 포함하지 못하는 등의 문제점이 발생하게 된다. 따라서 ��지를 사용하지 않고 높은 검사 각도를 발생할 수 있는 횡파 위상배열 초음파 탐촉자를 적용해야 할 필요성이 있다. 본 연구에서는 굴절각도가 높은 횡파를 발생할 수 있는 위상배열 초음파 탐촉자를 설계하고 제작하여 다양한 깊이의 EDM 노치가 가공된 시험편에서 결함이 정확하게 검출되고 평가될 수 있는 지를 확인하였다. 결과적으로 본 연구에서 설계된 횡파 위상배열 초음파 탐촉자는 다양한 깊이의 결함을 검출하고 신뢰성 있는 정밀도를 나타내었으므로 향후 접근제한이 예상되는 발전설비 구조물의 검사에 적용된다면 효과적인 검사 결과를 보여줄 것으로 기대된다. Typically, a wedge is involved to generate effectively high inspection angle in pipe weld inspection using phased array ultrasonic technique. But the usage of this wedge for weld or access limited area can cause coverage limitation for the examination volume because of the wedge front length. Therefore, the shear wave phased array probe which can generate high inspection angle without wedge is essentially necessary. In this paper, the shear wave phased array ultrasonic probe which can generate high inspection angle designed by modeling and manufactured from the modelling result. And this shear wave probe tested whether it can detect and sizing for EDM test block that contains various depth. As results, the experimental results show that the designed shear wave phased array probe can detect and size with reliable accuracy. Therefore if this phased array probe apply in field inspection, it is expected that it show more reliable inspection result for plant structure having access limitation.

Detailed optical characterization of three-dimensional visible-frequency polarization-independent carpet invisibility cloak

Abstract The invention of the three-dimensional woodpile photonic crystal by Costas M. Soukoulis and coworkers in 1994 has stimulated much further research—excellent research stimulates further research. Here, we report on using spatially inhomogeneous polymer woodpile structures in the long-wavelength limit as artificial graded-index structures. After briefly reviewing previous work on carpet invisibility cloaks designed by transformation optics, we present new experiments for various focus planes of the inspecting microscope as well as for different inspection angles in three-dimensional space. Numerical ray-tracing modeling is also provided. These data confirm our previous assessment that three-dimensional cloaking is quite robust for these structures.

不良項目別の有効視野範囲と目視角度に着目した新たな周辺視目視検査の作成手順の提案(理論・技術)

不良項目別の有効視野範囲と目視角度に着目した新たな周辺視目視検査の作成手順の提案(理論・技術)

Code inspection of welds using phased arrays

AbstractCritical welds need inspecting, because of either code requirements or structural integrity. Automated ultrasonics has proven more reliable than other techniques, such as radiography or manual techniques. Recently, portable phased arrays have become a dominant method of inspecting as they offer high speed, repeatable inspections. Techniques are available for a wide variety of vessels and pipes using commercial equipment. In addition, ASME section V now has five code cases available for phased array inspections of welds. One aspect of phased array inspections is that the coverage must be demonstrated using a scan plan, which can be a ray tracing programme showing the beam coverage, inspection angles, etc. This approach has big advantages for a flexible technology such as phased arrays; specifically, unusual weld profiles can be inspected using tailored scan plans. Unlike conventional ultrasonics or radiography, angles can be selected to optimise defect detection. Also, phased arrays can be adapted ...

Desenvolvimento de metodologia e estudo do potencial da técnica TOFD visando a inspeção e o monitoramento de equipamentos

Com o constante crescimento da indústria nacional, cresce também a demanda pelo desenvolvimento de ferramentas eficientes de inspeção e monitoramento da integridade estrutural de equipamentos e estruturas. Dentre estas, destacam-se os ensaios não destrutivos. Das diversas técnicas não destrutivas aplicadas para a inspeção de componentes, destaca-se o uso da técnica de ultra-som convencional para a localização e dimensionamento de defeitos. Porém, em inspeções de campo, devido ao desconhecimento freqüente da orientação dos defeitos, recorre-se a metodologias que utilizam diversos ângulos incidentes e sistemas de análise de sinais, resultando num processo lento e subjetivo de inspeção. Com o aumento da demanda por medidas on line, tem-se elevado a necessidade de processos mais rápidos e confiáveis, dentre estes, destaca-se o uso da técnica de ultra-som via time of flight diffraction (TOFD). Este trabalho apresenta a técnica TOFD como uma ferramenta eficiente na determinação da profundidade de entalhes usinados em blocos de aço SAE 1022, a partir da calibração segundo Norma Britânica BS 7706:1993. Para isso, foi elaborada uma metodologia utilizando quatro variações (freqüência/ângulo) diferentes de inspeção, verificando o potencial do método na análise das diferentes profundidades, a fim de aplicar na inspeção e no monitoramento de equipamentos. Os resultados mostram que tanto para defeitos aflorando na superfície de varredura quanto para defeitos aflorando na superfície oposta, o dimensionamento pode ser preciso, se a variação adequada (freqüência/ângulo) para cada caso for selecionada.

LED directivity measurement in situ

The paper presents the technique of LED directivity measurement in situ. A LED far-field pattern (FFP) can be measured quickly without dismantling the LEDs from the tile. The positioning device has been replaced by lighting a single LED in a tile, so the desired inspection angle has been obtained. Irradiance data then has been corrected for distance and sensor directivity. The resulting data set has been fitted with the approximation function. The obtained approximation is the representative of the average LED FFP. Brief analysis of an approximation function has been carried out. Four simple functions have been considered as candidates for such approximation. The L2-norm of the error between the original and fitted function was considered as an approximation quality criterion. Gaussian approximation has the best performance. For in situ technique performance evaluation, several sample tiles have been measured and the obtained outcome has been compared against goniometry results. The L2-norm of the LED FFP intensity error and viewing angle error are presented.

Confirming plant integrity by specialised NDE inspections

The UK power industry is going through a difficult period, trying to balance the demand for electricity with conforming to the new environmental regulations. Because of overcapacity, it is no longer an attractive proposition to build new power stations but, instead, it makes economic sense to keep older power stations running beyond their design life. Structural integrity is increasingly demanding greater accuracy and repeatability from NDE inspections; new equipment and technology has been developed predominantly based on ultrasonic and eddy current technology. The development of information technology has been crucial for the improvement of ultrasonic imaging techniques. Advanced specialist inspections including phased array, time-of-flight diffraction and advanced eddy current, have been developed for evaluation of steam pipework, generator end-rings, steam chests, blade roots, rotor bore and rotor discs and many other plant items. The latest phased array techniques bring considerable benefits to the inspection of complex geometries. Ultrasonic inspections on components with complex geometries can give rise to confusing signal patterns which influence the speed and integrity of inspections. Additionally, access restrictions often limit probe movement, further affecting test integrity. The development and utilisation of phased array ultrasonic hardware and analysis software, has enabled high-integrity high-speed scanning and imaging of complex components. 'Sweep Scanning' can be carried out from a static position allowing coverage where access is restricted; the data can then be stored for future interrogation if required. The phased array probe contains multiple elements, and scanning can be mechanical (probe movement), electronic (pulsed beam sweep), or a combination of both. Component drawings and geometries can be overlaid on the phased array images, enabling both inspection design and ease of analysis. Advantages are gained through scanning complex geometries quickly with high integrity. Focusing of the optimal inspection angle gives improved defect detection and electronic data storage enables an auditable inspection fingerprint. This paper concentrates on three main applications: phased array and time-of-flight diffraction applications, rotor bore applications and generator retaining ring (end-ring) applications.

On the considerations for the design of an automated aircraft sheet metal component production loft generation system

In this paper an ambitious production loft generation system (PLGS) is created to incorporate innovative and unique features of aircraft sheet metal component (SMC) lofts meeting the stringent standards of aircraft industry owing to non-availability of suitable public domain software. This system is fully tested and validated with the support of the aircraft industry. It provides for automated blank layout generation based on surface models utilizing some unique algorithms and vector logics created through research and development over a period of 15 years taking into account the material properties, flow direction and plasticity and strives to eliminate post forming trimming operations by utilizing the databases of the aircraft industry. For the first time such a custom built system is created, which incorporates industrial process data and provides a host of processing options, together with various design cum production features like mould lines, joggles, bend relief, tooling holes, pilot holes, cut outs, chamfers/fillets, inspection angles etc. and displays features needed for quality assurance as essential ingredients. It has inbuilt, intelligent, high efficiency processing features such as the utilization of symmetry facilitating fractional processing of the SMC. This paper includes a brief account of various issues related to the chronology of design of the systems, implementation of the design options, intricacies of methods deployed, their efficacy and combinatorial suitability. Crucial ground breaking new algorithms relevant to the production features are also elucidated in this paper.

Phased array ultrasonic NDT system for tubes and pipes

One or more phased array ultrasonic probes in the shape of conical section arcs, or an entire conical section ring, emit beams at a fixed incident angle with respect to the outer surface of a tube or pipe under inspection. At any given moment, these beams strike the tube at a single small entry zone from number of different directions. After being refracted at the inspection angle corresponding to the fixed angle of incidence, defects having longitudinal, transverse and oblique orientations are detected in the three-dimensional volume of the tube wall. The number of entry zones required for complete coverage of the outer surface of the tube is a function of the size of the tube, the speed at which it passes through the inspection station and the rate of rotation of the tube.

Application of phased array techniques to coarse grain components inspection

Ultrasonic inspection of cast stainless steel components from primary and auxiliary cooling circuits of French Nuclear Power Plant has to face with major difficulties due to the coarse grained structure of these materials. Attenuation losses and structural noise are encountered, which limits the performances of defect detection ability, mostly in terms of degraded signal-to-noise ratio and poor sensitivity. To overcome such problems, theoretical and experimental studies have been achieved at the French Atomic Energy Commission, with support from the French Institute for Radiological Protection and Nuclear Safety. Experimental studies have been performed over stainless steel specimen of known coarse structure (equiaxial grains and/or elongated grains), containing artificial reflectors (cylindrical holes and electro-eroded surface breaking notches). Those mock-ups have been inspected using contact probes of different array designs (linear or matrix splitting), and using pulse echo or dual-element techniques. Such arrays allow to control the ultrasonic beam so as to investigate different inspection angles and focusing depths. Experiments were carried out using oblique longitudinal waves, using delay laws computed by a specific model, taking account of acoustical and geometrical properties of the probes and the inspected component. In addition, specific reconstruction techniques have been investigated to enhance the signal-to-noise ratio as well as spatial resolution. These techniques are based on beam-forming summation and multi-angle inspections. Experimental results show that such techniques allow to reduce the speckle noise and to optimise the beam resolution. Those increased performances allow to detect and to size small planar defects located at the inner wall of a thick specimen, using corner and tip diffraction echoes.

Tracing tools to resolve neural circuits

In this paper we summarize neuroanatomical tracing methods, in particular combinations of methods designed to achieve the combined goals of tracing connectivity and extracting extra information from the projection or the target neurons. These combinations include techniques that identify projection fibres together with the neurons from which they originate, methods which establish the morphological or chemical identity of the target neurons and techniques to verify the presence of contacts between the terminal boutons on fibres and prospective target neurons. In the second part of this paper we describe a method recently developed in our laboratory, which consists of fluorescence tracing (introducing marker #1) combined with immunofluorescence with different fluorochromes (markers #2 and #3). This method enables us to observe the distribution of terminals of a particular set of projection fibres in contact with neurons belonging to two chemically different populations of interneuron. Multifluorescence confocal laser scanning is used for image acquisition of fibres and processes of presumed target neurons, and follow-up is by three-dimensional computer reconstruction. These reconstructions are used to determine that the contacts between the differentially labelled structures are real, i.e. with no optically empty space in between regardless of the angle of inspection. The specific experiments reported in this paper comprise the tracing with biotinylated dextran amine of fibres in the rat brain running from the presubiculum to layer III of the medial division of the entorhinal cortex. We studied the possibility of contacts in the latter area between the terminal boutons of these projecting fibres in association with presumed target neurons, i.e. parvalbumin and calretinin expressing interneurons.