Convex Defects Research Articles

The pulmonary-vascular-stump filling defect on CT post lung tumor resection: a predictor of cancer progression

BackgroundTo explore the pulmonary-vascular-stump filling-defect on CT and investigate its association with cancer progression.MethodsRecords in our institutional database from 2018 to 2022 were retrospectively analyzed to identify filling-defects in the pulmonary-vascular-stump after lung cancer resection and collect imaging and clinical data of patients.ResultsAmong the 1714 patients analyzed, 95 cases of filling-defects in the vascular stump after lung cancer resection were identified. After excluding lost-to-follow-up cases, a total of 77 cases were included in the final study. Morphologically, the filling-defects were dichotomized as 46 convex-shape and 31 concave-shape cases. Concave defects exhibited a higher incidence of increase compared to convex defects (51.7% v. 9.4%, P = 0.001). Among 61 filling defects in the pulmonary arterial stump, four (6.5%) increasing concave defects showed the nuclide concentration on PET and extravascular extension. The progression-free survival (PFS) time differed significantly among the concave, convex, and non-filling-defect groups (log-rank P < 0.0001), with concave defects having the shortest survival time. Multivariate Cox proportional hazards analysis indicated that the shape of filling-defects independently predicted PFS in early onset on CT (HR: 0.46; 95% CI: 0.39–1.99; P = 0.04). In follow-ups, the growth of filling-effects was an independent predictor of PFS (HR: 0.26; 95% CI: 0.11–0.65; P = 0.004).ConclusionsCertain filling-defects in the pulmonary-arterial-stump post lung tumor resection exhibit malignant growth. In the early onset of filling-defects on CT, the concave-shape independently predicted cancer-progression, while during the subsequent follow-up, the growth of filling-defects could be used independently to forecast cancer-progression.

Effect of complexing agent on iron base zinc-nickel alloy coating

The influence of four complexing agents on corrosion resistance of Zinc-Nickel (Zn-Ni) alloy coating was investigated. The current density and plating time were determined by Hull and rectangular tank experiments. The effects of triethanolamine, potassium sodium tartrate, tetraethylenepentamine and sodium citrate on the properties of iron-based Zn-Ni alloy coatings were studied under the same electroplating process. The surface morphology, structure, elemental composition and corrosion resistance of Fe-base Zn-Ni alloy coatings with different complexing agents were analyzed. The surface and morphology of the coating were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The anticorrosive properties of the coating were evaluated by electrochemical electrode and electrochemical impedance spectroscopy (EIS). The self-corrosion current density of triethanolamine is 2.927e-005A·cm−2, the rate of corrosion is minimal, rendering the material highly resistant to corrosion; the surface remains flat and exhibits a dense texture. The content of potassium, sodium, Zn and Ni in tartrate increased, thus reducing the corrosion resistance and flatness of the coating. The self-corrosion current density was 9.400e-005A·cm−2. The surface was rough and uneven, and there were a large number of large concave and convex defects. The complexing agent enhances the adhesion and corrosion resistance of the coating, improves the optical and mechanical properties of the coating, adjusts the durability and stability of the coating, increases the crystal packing density, increases the coating thickness, improves the adhesion with the substrate interface, and optimizes the uniformity of grain distribution. These factors are the key factors that determine the corrosion behavior of Zn-Ni coatings. In the process of electroplating, the addition of complexing agent can improve the quality of the coating, and suitable complexing agent can obtain smooth and bright coating at the same time, make the corrosion resistance of the coating higher.

Design of an optical linear-discriminant filter: optimization for enhancement of filter transmittance and discrimination accuracy.

To discriminate fine concave and convex defects on a dielectric substrate, an optical machine learning system is proposed. This system comprises an optical linear-discriminant filter (OLDF) that performs linear discriminant analysis (LDA) of the scattered-wave distribution from target samples. However, the filter output from the OLDF is considerably weak and cannot be measured experimentally. Therefore, an algorithm is also proposed to improve the discrimination accuracy and filter transmittance. The designed filter is validated using a rigorous optical simulator based on vector diffraction theory. We also analyze and discuss a mechanism that provides high transmittance with high discrimination accuracy.

Surface morphology and oxidation evolution of glow discharge polymer capsules during tumble polishing

Glow discharge polymer (GDP) capsules are often used as the ablation layer in laser inertial confinement fusion (ICF) research, because of its excellent properties in low X-ray opacity, high tensile strength, and high thermal conductivity. The isolated surface defects and distribution of oxygen content on the surface of GDP capsules can lead to the increase of hydrodynamic instability and the decrease of compression efficiency. In this work, by using media spheres and silica nanoparticles, a tumble polishing device for GDP capsule polishing is built to improve the surface morphology. The effects of polishing parameters on the surface roughness and oxygen content of GDP were investigated. The test results show that tumble polishing can effectively remove convex defects, only 24 identified defects with a height below 231 nm were found after 144 h polishing, reduce the surface roughness (∼10 nm) and improve the surface quality of GDP capsules. Moreover, the oxygen content distribution on the surface of GDP is uniform after tumble polishing. And the depth analysis results show that the tumble polishing has no obvious effect on the change of oxygen content in GDP shell under the surface layer.

Detection Method of Protruding Defects of Parts Based on Improved Threshold Segmentation

Aiming at a series of problems that the traditional threshold segmentation method has low detection accuracy in detecting part bulge defects, a part bulge defect detection method based on improved threshold segmentation is proposed in this paper. Firstly, the parts to be tested are obtained, and then the image is filtered and denoised. Because the traditional median filter has some limitations, a fast weighted median filtering algorithm is proposed. Then the image is enhanced, and the method based on Laplace operator is used to enhance the image. Then Otsu threshold segmentation and iterative threshold segmentation are used respectively. It is found that there are still many non convex defects, which have a great impact on the detection accuracy. Therefore, an improved iterative threshold segmentation is proposed. The difference operation is carried out between the standard part and the part to be tested, and the above three methods are compared. The results indicate that the better iterative threshold segmentation method can effectively test the convex fault of the compent.

Analysis of the residual stress and surface morphology of TI6AL4V using elastoplastic contact ultrasonic rolling

As ultrasonic rolling mainly affects the residual stress and surface morphology of Ti6Al4V, it is of great significance to study different process parameters, such as amplitude, static pressure, time, and step length, thereby improving the performance of Ti6Al4V. However, unstable bouncing caused by the elastic relationship between the indenter and the sample is inevitable. Based on finite-element analysis and Hertz contact theory, the concept of critical damping was proposed to quickly stabilize the system. Therefore, a three-dimensional finite-element model was established using the ABAQUS software, after which the ultrasonic-rolling process was simulated by applying static pressure on the sample surface using a spring. Then, the distribution of residual stress under different amplitudes, static pressures, times, and step lengths was analyzed. Based on simulation and experimental results showed that the maximum residual stress of −689.802 MPa was obtained when the amplitude, static pressure, and time were 10 µm, 600 N, and 0.064 s, respectively. When the step length was 1/2 of the indentation width, the surface stress concentration was obvious, convex defects were large, and surface roughness Ra increased to 1.076 µm. Investigations also revealed that when the step length was 1/8, Ra decreased by 39.68% compared with that when the step length was 1/2, the thickness of the plastic-deformation layer reached 56.07 µm. When the step length was 1/10, the maximum compressive residual stress reached −888.007 MPa and Ra increased. On the basis of the abovementioned optimization parameters, the influence of step length on the properties of Ti6Al4V alloy was further explored, and direction for the strengthening process of Ti6Al4V alloy by studying the pattern of surface strengthening was presented.

Experimental evaluation of multi-jointed soft detection arm of geometry inspection gauges for detecting internal convex defects in natural gas pipelines

Regular deformation inspection of in-service natural gas pipelines can reduce accidents caused by pipeline failure. In this study, a novel contact-testing geometry inspection gauge is proposed, and its multi-jointed soft detection arm is the focus of our study. 3D printing technology and mold casting were used to fabricate a newly designed detection arm. A finite element method was used to analyze the process of the detection arm passing through the convex defect and optimize its joint number. Then, a series of comparison experiments were conducted with various convex defects to evaluate the superiority of the measuring performance of the multi-jointed soft detection arm. The experimental results show that compared to the no-jointed detection arm, the multi-jointed detection arm has a more accurate experimental value, especially for defects with closer heights (8 and 10 mm) and is relatively more stable in repeated experiments. This study provides options for the design of a flexible caliper pipeline inspection gauge for deformation inspection in pipelines.

Design of an optical linear discriminant filter for classification of subwavelength concave and convex defects on dielectric substrates.

Identification of the defect type on substrate materials is essential for enhancing their yield ratio. We propose a novel optical filter to discriminate between subwavelength-order concave and convex defects on flat surfaces. This filter performs Fisher's linear discriminant analysis using light wave diffraction. The defect type is discriminated by simply comparing the irradiance at an observation point with the threshold value. Neither the defect image nor phase data, nor a large amount of data processing by a computer, is necessary. Numerical discrimination simulations indicate a discrimination error of 0.85%, and the noise tolerance of the proposed system is also discussed.

Intelligent detection technology of flip chip based on H-SVM algorithm

The Flip Chip (FC) technology has been widely used in microelectronic packaging, and the FC technology requires not only higher precision, but also higher reliability, which makes the defect detection of FC more challenging. In this paper, the SAM image of FC is segmented. Histogram of oriented gradient (HOG) as a feature extraction method and optimized support vector machines (SVM) are combined to design an intelligent diagnosis algorithm, which was called H-SVM. This method was used to realize the defect detection of solder bumps. In the same variable environment, it evaluates and compares with other machine learning algorithms. The results show that it is effective to combine HOG and optimized SVM for the diagnosis of convex defects with high detection accuracy.

Relationship among Welding Defects with Convection and Material Flow Dynamic Considering Principal Forces in Plasma Arc Welding

The material flow dynamic and velocity distribution on the melted domain surface play a crucial role on the joint quality and formation of welding defects. In this study, authors investigated the effects of the low and high currents of plasma arc welding on the material flow and thermodynamics of molten pool and its relationship to the welding defects. The high-speed video camera (HSVC) was used to observe the convection of the melted domain and welded-joint appearance. Furthermore, to consider the Marangoni force activation, the temperature on the melted domain was measured by a thermal HSVC. The results revealed that the velocity distribution on the weld pool surface was higher than that inside the molten weld pool. Moreover, in the case of 80 A welding current, the convection speed of molten was faster than that in other cases (120 A and 160 A). The serious undercut and humping could be seen on the top surface (upper side) and unstable weld bead was visualized on the back side (bottom surface). In the case of 160 A welding current, the convection on the weld pool surface was much more complex in comparison with 80 A and 120 A cases. The excessive convex defect at the bottom side and the concave defect at the top surface were observed. In the case of 120 A welding current, two convection patterns with the main flow in the backward direction were seen. Almost no welding defect could be found. The interaction between the shear force and Marangoni force played a solid state on the convection and heat transportation processes in the plasma arc welding process.

Asymptotic behaviour of the Oore-Burns integral for cracks with a corner and correction formulae for embedded convex defects

In this paper, the asymptotic behaviour of the stress intensity factor (SIF) near a corner of a crack is discussed. The weight function of Oore-Burns and FE analysis are used in order to explain the trend of the SIF. The analytical analysis shows that the SIF at the corner has a cusp behaviour as a function of the distance from the corner. This is a crucial mathematical property obtained from the Oore-Burns integral. Explicit formulae for the estimation of the SIF are obtained for square and equilateral triangular cracks. Then, the value of the SIF along the crack border is corrected (quantitative intervention) by means of a new simple formulation that is able to considerably increase the accuracy of the Oore-Burns integral. Finally, in the case of a crack with a rounded corner, a new simple correction formula is given and, in order to check the accuracy of the proposed equations, a comparison is carefully made with an FE analysis as well as with numerical results taken from the literature.

Detection Method of Micro Concave and Convex Defects on Small Metal Parts by Using Multi-Directional Illumination Images

Detection Method of Micro Concave and Convex Defects on Small Metal Parts by Using Multi-Directional Illumination Images

Research on Gesture Recognition Based on Improved Canny & K-Means Algorithm and CNN

In view of the problem that the current dynamic gesture recognition system has decreased recognition rate and recognition speed due to the increase of sample size,in this study, we first use the improved Canny operator to detect the edge of the hand image. The improved algorithm includes two aspects: one is to generate HSV space image converted from RGB space and extract the V-component image; the other is to transform the traditional Gauss filter into a bilateral filter which integrates spatial distance and similarity to denoise;Then the improved K-means clustering algorithm is used to extract the feature points on the edge of the hand image. In the improved method, the pixel points at the peak of histogram are used as the initial clustering center, and the number of peak points is used as the number of classification;Then, the detection algorithm of convex hull and convex defect with geometric features is used to realize the effective fingertip tracking;Finally, CNN is used to achieve the precise sorting of fingertips.After verification, this synthesis algorithm can effectively solve the problems such as the difficulty to accurately detect the hand image contour, the poor fingertip tracking effect and the disorder of fingertip sorting caused by the similarity of background color and skin color, and the small difference between the length of fingers. With the increase of sample size, the recognition rate and speed have also improved, which can be widely used in dynamic gesture recognition and other fields.

Hand Gesture Recognition using Convexity Defect

Gestures are the simplest way of conveying a message, rather simpler than verbal means. It is the most primitive way of conversation. Gestures can also be the easiest and intuitive way of communicating with a computer, they can be used to communicate or convey information to computers, robots, smart appliances and many other pieces of machinery. It can eliminate the use of mouse and keyboard to some extent. The gestures cited are basically the variable positions as well as orientations of the hand. They can be detected by a simple webcam attached to the computer. The image is first changed into its corresponding RGB values and then to HSV values for better handling and feature recognition. The hand is segregated from the background using feature extraction. Then the values are matched in proximity of the coded values. Then the region of interest is calculated using the concept of convexity and background subtraction. The convex defect helps to define the contour efficiently. This method is invariant for different positions or direction of the gesture. It is able to detect the number of fingers individually and efficiently.

Twin-illumination and Subtraction Technique for Detection of Concave and Convex Defects on Steel Pipes in Hot Condition

Twin-illumination and Subtraction Technique for Detection of Concave and Convex Defects on Steel Pipes in Hot Condition

Enhancement of laser-induced damage threshold of optical coatings by ion-beam etching in vacuum environment

Ion-beam sputtering (IBS) method was used to etch the different thickness of the outer layer overcoat for high reflection film. Laser resistance improvements enabling to exceed 1.5× have been observed on high reflection coatings. The smoothing process of surface and subsurface convex defect induced by ion-beam etching caused the decreasing electric field intensity. A process model was presented to understand the smoothing process of surface and subsurface convex defect. The decreasing electric field intensity, accompanying with small surface roughness value, low defect density and organic contamination adsorption concentration of sample surface, was attributed to the high laser-induced damage threshold in vacuum environment.

Battery Surface and Edge Defect Inspection Based on Sub-Regional Gaussian and Moving Average Filter

Detecting the defects of a battery on the surface and edge has always been difficult, especially for concave and convex ones, thereby seriously affecting its quality. Thus, sub-regional Gaussian and moving average filtering are innovatively proposed in this study considering the effect of the nonuniform background illumination of the battery edge and the difference between the edge background and the internal surface defects of the battery. The battery surface image is divided into two areas, namely, edge area W 1 and inner area W 2 . Gaussian and moving average filtering are carried out row-by-row and column-by-column in the inner area W 2 and the edge area W 1 , respectively. The algorithm is tested on 600 battery samples that mainly possess concave and convex defects. The proposed method has higher detection accuracy and lower omission detection rate than the traditional unpartitioned processing method, especially in detecting the accuracy of edge defects. The accuracy rates were approximately 20% higher than that obtained by the traditional processing algorithm. The proposed method has remarkable real-time performance that can process four 8192 × 10,240 pixel battery images per second, thereby meeting the industrial production line speed requirements while satisfying accuracy. The proposed method has been applied in actual production for defect inspection.

Real-time dynamic gesture recognition and hand servo tracking using PTZ camera

A technology of real-time dynamic gesture recognition and hand tracking using a Pan-Tilt-Zoom (PTZ) camera was presented in this study. It was aimed to achieve robust scheme that stably recognized simple hand gestures and tracked the hand by means of a PTZ camera to keep the fingertip remaining in the center of the camera. For this purpose, the hand region was initially segmented in a cluttered environment using skin color segmentation in YCbCr color space to get the silhouette of the hand. Furthermore, the Monte Carlo Sampling method was used to estimate the Cubic Bezier curves best fitted to the sub contour points centralized in each contour point, and the fingertips were detected by combining the local maximums of a cumulative curvature with detection of convex defects. After that, feature triangle analysis was utilized to achieve dynamic recognition of simple gestures including “right click down” and “right click up”. Finally, the PTZ camera was driven by the algorithm to achieve servo tracking with the target fingertip when the gesture “right click down” was detected. As is shown by the experimental results, the proposed approach recognized the dynamic gestures and located the fingertips’ positions precisely, and realized the follow-up servo tracking using PTZ camera in real-time.

Fast Measurement Method of Gear Parameters Based on Convexity Defect

Gear parameters measurement based on machine vision is an important part in the field of intelligent manufacturing. Existing methods, which are all based on gear center, may cause accumulative error and have the weakness of large computation and low efficiency due to the repeated use of all contour points. In view of these problems, a new measurement method of gear parameters based on convexity defect is presented. Firstly, a gear contour is extracted from the gear image. Secondly, convex hull and defects of the gear contour are computed using image processing approach, then the number of the gear teeth and key points on the dedendum circle and addendum circle are determined, respectively. Finally, each radius of the dedendum circle and addendum circle is obtained separately by means of circle fitting with the corresponding key points. In this method, the key points are calculated by using the properties of convex defects, avoiding the calculation of the gear center and greatly increasing the computing speed by using a limited number of key points, precisely, two times the number of gear teeth. Compared with the traditional methods, the experimental results show that the speed of this method is increased by 1.5 times and it can meet the real-time requirement.

Automatic visual inspection method for a coated surface having an orange peel effect

In many production processes, defect detection has played an important role in preventing the outflow of defective products. As such, there are still many production lines that rely on an inspector's visual observation. In this study, using fluorescent tubes as an irradiation light source, we propose a simple and effective visual inspection method for detecting convex defect on painted surfaces having an orange peel effect. The proposed method detects and distinguishes painted surface defects in an area illuminated by fluorescent tubes, using the combination of local segmented results and gradient information computed with different differential operations. The inspection device for detecting the defect can be easily installed in the production line without changing the production line, and can be constructed at a low cost without using additional adaptations. The performance of the proposed method was evaluated with the data of real products captured with an inspection device installed on the production line. Experimental results show that this method can provide a better detection in the inspection region with a low false‐detection rate. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.