Contour Position Research Articles

Aided assembly technology of satellite honeycomb sandwich panel insert based on virtual and real fusion

Abstract Aiming at the problems of frequent low-level quality and difficulty in improving assembly efficiency in the assembly process of satellite honeycomb sandwich panel insert, the 3D model of the honeycomb sandwich panel is formed into high-definition model projection image by feature processing and extraction for 3D process information, and the virtual-real fusion insert aided assembly system is constructed, which is composed of core components such as camera, high-definition projector, and measurement software. Through structured light projection technology and projection algorithm based on landmark point transformation, the projection image can be accurately matched with the contour and hole position of the physical, structural panel, which can effectively assist the assembly process of the insert and reduce the low-level quality problems such as wrong use of parts and reverse polarity assembly. Compared with the traditional manual assembly method, the efficiency is improved by more than 200%, and the error rate is reduced by more than 300%.

Prediction of Surface Roughness Components in Turning with Single Point Tool—Measurement of Tool Edge Contour and Prediction of its Position During Cutting—

Surface roughness is affected by the tool geometry, feed rate, overcutting by built-up edge, and tool vibration in the depth of the cut direction. However, dividing the roughness value into each component is difficult. Therefore, a new prediction method for the position of the tool contour on the roughness curve is proposed to divide the measured roughness value into components. This proposed method consists of two processes. In one, the roughness curve is divided into the roughness curve formed during each revolution of the work material regardless of the clarity of the feed marks. The other is the process that predicts the vertical position of the tool contour. If the vertical position of the tool contour can be predicted, the vibration and overcutting components of roughness can also be predicted. In this study, the transition of roughness components such as the theoretical roughness, vibration width, and overcutting is studied with the increase in the cutting distance in the turning of chromium molybdenum steel, JIS SCM435. When supplying a 10% emulsion mist, the measured Rz is smaller than that of the dry condition. In both the dry and mist supply conditions, the measured Rz increases from the beginning of cutting then decreases and then increases again with the increase in the cutting distance. The largest component of the total roughness in both the dry and mist supply conditions is the theoretical roughness Rth. The ratio ranges between 50.3% and 78.7%. Regardless of the cutting conditions, the vibration width in the depth of the cut direction is relatively constant. The overcutting slightly increases after the start of cutting, then decreases when the maximum contact length exceeds approximately 0.1 mm. The proposed method verifies the ratio of the surface roughness components and is an effective method for improving the surface roughness.

Chinese expert consensus on the construction of the fluoroless cardiac electrophysiology laboratory and related techniques.

Transcatheter radiofrequency ablation has been widely introduced for the treatment of tachyarrhythmias. The demand for catheter ablation continues to grow rapidly as the level of recommendation for catheter ablation. Traditional catheter ablation is performed under the guidance of X-rays. X-rays can help display the heart contour and catheter position, but the radiobiological effects caused by ionizing radiation and the occupational injuries worn caused by medical staff wearing heavy protective equipment cannot be ignored. Three-dimensional mapping system and intracardiac echocardiography can provide detailed anatomical and electrical information during cardiac electrophysiological study and ablation procedure, and can also greatly reduce or avoid the use of X-rays. In recent years, fluoroless catheter ablation technique has been well demonstrated for most arrhythmic diseases. Several centers have reported performing procedures in a purposefully designed fluoroless electrophysiology catheterization laboratory (EP Lab) without fixed digital subtraction angiography equipment. In view of the lack of relevant standardized configurations and operating procedures, this expert task force has written this consensus statement in combination with relevant research and experience from China and abroad, with the aim of providing guidance for hospitals (institutions) and physicians intending to build a fluoroless cardiac EP Lab, implement relevant technologies, promote the standardized construction of the fluoroless cardiac EP Lab.

A Novel Decoupled Feature Pyramid Networks for Multi-Target Ship Detection.

The efficiency and accuracy of ship detection is of great significance to ship safety, harbor management, and ocean surveillance in coastal harbors. The main limitations of current ship detection methods lie in the complexity of application scenarios, the difficulty in diverse scales object detection, and the low efficiency of network training. In order to solve these problems, a novel multi-target ship detection method based on a decoupled feature pyramid algorithm (DFPN) is proposed in this paper. First, a feature decoupling module is introduced to separate ship contour features and position features from the multi-scale fused features, to overcome the problem of similar features in multi-target ships. Second, a feature pyramid structure combined with a gating attention module is constructed to improve the feature resolution of small ships by enhancing contour features and spatial semantic information. Finally, a feature pyramid-based multi-feature fusion algorithm is proposed to improve the adaptability of the network to changes in ship scale according to the contextual relationship of ship features. Experiments on the multi-target ship detection dataset showed that the proposed method increased by 6.3% mAP and 20 FPS higher than YOLOv4, 7.6% mAP and 36 FPS higher than Faster-R-CNN, 5% mAP and 36 FPS higher than Mask-R-CNN, and 4.1% mAP and 35 FPS higher than DetectoRS. The results demonstrate that the DFPN can detect multi-target ships in different scenes with high accuracy and a fast detection speed.

Active contour model based on local Kullback–Leibler divergence for fast image segmentation

The inhomogeneity of image intensity and noise are the main factors that affect the segmentation results. To overcome these challenges, a new active contour model is designed based on level set method and Kullback–Leibler Divergence. First of all, a new regional measurement of information scale is applied to construct energy functional, instead of Euclidean distance. Test results demonstrate that the Kullback–Leibler Divergence achieves a truly better segmentation. Then, a new Heaviside function has been proposed in this paper, which gives rise to a faster zero-crossing slope than traditional function. In this sense, it can stimulate the evolution of the level set function faster and allocate internal and external energy reasonably. In addition, the activation function has also been improved, which makes itself fluctuates over a smaller range than former activation function. Experiments reveal that the ‘Local Kullback–Leibler Divergency’ (LKLD) model has desired segmentation results both on real-world and medical images. Also, it owns a better noise robustness and is not limited to position of initial contour.

The Dynamical Tropopause Location as a Potential Predictor for North Atlantic Tropical Cyclone Activity

Abstract Tropical cyclones are among the most devastating natural phenomena that can cause severe damage when undergoing landfall. In the wake of the poorly forecast 2013 North Atlantic hurricane season, Rossby wave breaking on the 350-K isentropic surface has been linked to tropical cyclone activity measured by the accumulated cyclone energy (ACE). Here, ERA5 data and HURDAT2 tropical cyclone data are used to argue that the latitude of the 2 potential vorticity unit (PVU; 1 PVU = 10−6 K kg−1 m2 s−1) contour on the 360-K isentropic surface in the western North Atlantic is linked to changes in vertical wind shear and relative humidity during the month of September. A more equatorward position of the 2-PVU contour is shown to be linked to an increase in vertical wind shear and a reduction in relative humidity, as manifested in an increased ventilation index, in the tropical western North Atlantic during September. The more equatorward position is further linked to a reduction in the number of named storms, storm and hurricane days, hurricane lifetime, and number of tropical cyclones making landfall. Changes in genesis location are shown to be of importance for the changes in landfall frequency and hurricane lifetime. In summary, the 2-PVU contour latitude in the western North Atlantic can, therefore, potentially be used as a predictor in seasonal and subseasonal forecasting. Significance Statement Forecasts for the North Atlantic hurricane season are operationally produced. Their aim is to predict the number of tropical cyclones and their total energy throughout the season. This study proposes to include the tropopause latitude in these forecasts, as it is shown to be linked to vertical wind shear and midtropospheric relative humidity in the western tropical North Atlantic. The tropopause latitude is thereby linked to the number of tropical cyclones, their lifetime, and the total energy throughout the season. This link is particularly strong during September.

Research on the Cause and Control Method of Edge Warping Defect during Hot Finishing Rolling

Different from the cross-section profile defects caused by uneven roll wear or external forces during hot finishing rolling, the edge warping defect often occurs and has special local characteristics. However, the cause and control method of edge warping are still unclear. By superposition calculating the roll shape, it is found that the high-order comprehensive roll gap contour formed by the superposition of the bathtub-shaped roll thermal contour and parabolic original roll shape is the main cause of strip edge warping. To ensure that the comprehensive roll gap contour is parabolic rather than the original roll shape, the target curve of the comprehensive roll contour in the form of a parabola is determined according to the amplitude of the middle position of the comprehensive roll contour of the last strip in a standard rolling unit, and then subtract the thermal contour curve of the last strip to obtain the desired curve of the antithermal original roll shape. In theory and application, the optimization of the original roll shape can effectively avoid the occurrence of edge warping defect.

Splitting ore from X-ray image based on improved robust concave-point algorithm.

Image segmentation is a key part of ore separation process based on X-ray images, and its segmentation result directly affects the accuracy of ore classification. In the field of ore production, the conventional segmentation method is difficult to meet the requirements of real-time, robustness and accuracy during ore segmentation process. In order to solve the above problems, this article proposes an ore segmentation method dealing with pseudo-dual-energy X-ray image which is composed of contour extraction module, concave point detection module and concave point matching module. In the contour extraction module, the image is firstly cut into two parts with high and low energy, then the adaptive threshold is used to obtain the ore binary image. After filtering and morphological operation, the image contour is obtained from the binary image. Concave point detection module uses vector to detect concave points on contour. As the main contribution of this article, the concave point matching module can remove the influence of boundary interference concave points by drawing the auxiliary line and judging the relative position of auxiliary line and ore contour. With the matching concave points connected, the whole ore segmentation is completed. In order to verify the effectiveness of this method, a comparative experiment was conducted between the proposed method and conventional segmentation method using X-ray images of antimony ore as data samples. The result of industrial experiment shows that the proposed intelligent segmentation method can remove the interference of pseudo concave points on the contour, achieve accuracy segmentation result, and satisfy the requirements of processing X-ray image of ore.

Correction to: A hybrid active contour image segmentation model with robust to initial contour position

Correction to: A hybrid active contour image segmentation model with robust to initial contour position

A Novel Adaptive Fractional Differential Active Contour Image Segmentation Method

When the image is affected by strong noise and uneven intensity, the traditional active contour models often cannot obtain accurate results. In this paper, a novel adaptive fractional differential active contour image segmentation method is proposed to solve the above problem. At first, in order to extract more texture parts of the image, an adaptively fractional order matrix is constructed according to the gradient information of the image, varying the fractional order of each pixel. Then, the traditional edge-stopping function in the regularization term is susceptible to noise, and a new fractional-order edge-stopping function is designed to improve noise resistance. In this paper, a fitting term based on adaptive fractional differentiation is introduced to solve the problem of improper selection of the initial contour position leading to inaccurate segmentation results so that the initial contour position can be selected arbitrarily. Finally, the experimental results show that the proposed method can effectively improve the segmentation accuracy of noise images and weak-edge images and can arbitrarily select the position selection of the initial contour.

Chu-aesthetic gauges: The precision implement for aesthetic crown lengthening and evaluation of biologic width

Chu aesthetic gauges are one of their own kind and unique set of devices that uses adequate crown proportions to determine the exact position of the osseous contour supporting the teeth in concern. The aim of this study was to perform aesthetic crown lengthening using these gauges and evaluate the healing of biologic width. 15 systemically healthy patients participated in this study. Aesthetic crown lengthening was performed in the maxillary anteriors using these gauges. Along with this evaluation of level of biologic width was done at baseline, 3months and 6 months. The literature indicated that even though periodontal tissue remodels after surgery and positional changes are noted but they get stabilized after three months. Besides this, the biologic width re- establishes itself to original vertical levels by 3 months and it attains a proper state of equilibrium in about 6 months. The authors concluded that it was possible using Chu-aestehtic gauges, to achieve ideal crown length-width ratio. At the same time it yielded a beneficial biologic width level for future restorative or prosthetic purpose. The unique approach by these gauges is an innovative and novel method in modern era.

A hybrid active contour image segmentation model with robust to initial contour position

A hybrid active contour image segmentation model with robust to initial contour position

Object Extraction of Tennis Video Based on Deep Learning

Moving target detection and tracking technology is the core technology in the field of computer vision. It integrates image processing, pattern recognition and intelligence, and artificial intelligence and automatic control are the keys to an intelligent video surveillance system. The method acquires video image signals through visible light or infrared sensors, performs digital image processing on the video images, detects moving targets, and then extracts moving targets for target recognition. Then, the moving target is predicted and tracked according to the image features and spatiotemporal features, and the contour shape, position, and motion trajectory of the target are obtained, which provides data support for subsequent tasks. This paper uses the convolutional neural network model HyperNet as the technical support to study the deep learning (DL) tennis video target extraction. The final experimental results show that the loss value of the loss function in the training process of this method is stably maintained between 1.5% and 2.5%, and the speed performance is also greatly improved. The number of boxes for extracting candidate regions is significantly reduced, the calculation time for each frame will not exceed 1.8 s, the orientation accuracy of target extraction is 96.32%, and the size accuracy is 91.05%.

An active contour model algorithm combined with anisotropic diffusion filtering and global pre-fitting energy

Traditional local active contour models mainly depend on the data fitting term to obtain image edge information, which are sensitive to the position of initial contour. In fact, setting an unreasonable initial contour will result in a time-consuming image segmentation process and difficult evolution at weak boundary. To solve this problem, we come up with a second-order edge detection operator which is based on the global gradient image information to replace the traditional data fitting term, and to obtain edge information with higher speed and accuracy. In addition, the anisotropic edge enhancement method has been introduced to improve the robustness to the weak boundary. In this way, an active contour model which is insensitive to initial contour position is proposed to achieve a faster and more accurate image segmentation result.

ADAPTIVE INITIAL CONTOUR AND PARTLY-NORMALIZATION ALGORITHM FOR IRIS SEGMENTATION OF BLURRY IRIS IMAGES

Iris segmentation is a process to isolate the accurate iris region from the eye image for iris recognition. Iris segmentation on non-ideal and noisy iris images is accurate with active contour. Nevertheless, it is currently unclear on how active contour responds to blurry iris images or motion blur, which presents a significant obstacle in iris segmentation. Investigation on blurry iris images, especially on the initial contour position, is rarely published and must be clarified. Moreover, evolution or convergence speed remains a significant challenge for active contour as it segments the precise iris boundary. Therefore, this study carried out experiments to achieve an efficient iris segmentation algorithm in terms of accuracy and fast execution, according to the aforementioned concerns. In addition, initial contour was explored to clarify its position. In order to accomplish these goals, the Wiener filter and morphological closing were used for preprocessing and reflection removal. Next, the adaptive initial contour (AIC), δ, and stopping function were integrated to create the adaptive Chan-Vese active contour (ACVAC) algorithm. Finally, the partly -normalization method for normalization and feature extraction was designed by selecting the most prominent iris features. The findings revealed that the algorithm outperformed the other active contour-based approaches in computational time and segmentation accuracy. It proved that in blurry iris images, the accurate initial contour position could be established. This algorithm is significant to solve inaccurate segmentation on blurry iris images.

Topological Friction and Relaxation Dynamics of Spatially Confined Catenated Polymers.

We study catenated ring polymers confined inside channels and slits with Langevin dynamics simulations and address how the contour position and size of the interlocked or physically linked region evolve with time. We show that the catenation constraints generate a drag, or topological friction, that couples the contour motion of the interlocked regions. Notably, the coupling strength decreases as the interlocking is made tighter, but also shorter, by confinement. Though the coupling strength differs for channel and slit confinement, the data outline a single universal curve when plotted against the size of the linked region. Finally, we study how the relaxation kinetics changes after one of the rings is cut open and conclude that considering interlocked circular polymers is key for isolating the manifestations of topological friction. The results ought to be relevant for linked biomolecules in experimental or biological confining conditions.

An Automatic Extraction Method for Hatched Residential Areas in Raster Maps Based on Multi-Scale Feature Fusion

Extracting the residential areas from digital raster maps is beneficial for research on land use change analysis and land quality assessment. In traditional methods for extracting residential areas in raster maps, parameters must be set manually; these methods also suffer from low extraction accuracy and inefficiency. Therefore, we have proposed an automatic method for extracting the hatched residential areas from raster maps based on a multi-scale U-Net and fully connected conditional random fields. The experimental results showed that the model that was based on a multi-scale U-Net with fully connected conditional random fields achieved scores of 97.05% in Dice, 94.26% in Intersection over Union, 94.92% in recall, 93.52% in precision and 99.52% in accuracy. Compared to the FCN-8s, the five metrics increased by 1.47%, 2.72%, 1.07%, 4.56% and 0.26%, respectively and compared to the U-Net, they increased by 0.84%, 1.56%, 3.00%, 0.65% and 0.13%, respectively. Our method also outperformed the Gabor filter-based algorithm in the number of identified objects and the accuracy of object contour locations. Furthermore, we were able to extract all of the hatched residential areas from a sheet of raster map. These results demonstrate that our method has high accuracy in object recognition and contour position, thereby providing a new method with strong potential for the extraction of hatched residential areas.

Developments of Adapted Clothing for Physically Disabled People with Scoliosis Using 3D Geometrical Model

Scoliosis is a deformity of the spine that causes disorders of the rib cage. This makes it difficult to design clothes for affected people without following the shape of the rib cage. This paper presents a new 3D clothing design method based on virtual reality for women with physical disabilities such as scoliosis. The current design method is a variation of the draping techniques commonly used by fashion designers to design clothes on a mannequin or human body. However, the current design process highly considers the skeleton and body scan of the person. The skeleton is used to detect the anthropometric points of the patient, while the body scan allows us to detect the morphological contours at the onset of scoliosis. Thus, both allow us to accurately track the patient’s morphology and atypical shape. The position of the morphological contours is indicated by reference marks that are closely associated with the skeleton. This helps to automatically adapt the garment to the evolution of the patient’s pathology over time. The process of creating the 3D garment was processed based on the 3D model of the thorax, which helps to easily determine the anthropometric points and the morphological curves. Using this data, the geometrical model of the garment could be created with 3D ease allowances. The 2D block pattern was then obtained by flattening the 3D patterns using flattening methods. Finally, various tests were performed considering the evolution of pathology to predict the future garment. These tests validate our geometrical model of the garment with 3D ease allowances by comparing the results with previous work.

Reconstruction of isostatically adjusted paleo-strandlines along the southern margin of the Laurentide Ice Sheet in the Great Lakes, Lake Agassiz, and Champlain Sea basins

Strandlines document the former presence of lakes and a sea in east-central North America along the southern margin of the retreating Laurentide Ice Sheet (LIS). The strandlines of these formerly level water bodies are uplifted to the north and provide evidence of glacial isostatic adjustment (GIA) of the Earth’s crust to the former ice load. We compile published ages and measurements of the present elevation and location of shore features in the strandlines of eight major paleo-water bodies from the St. Lawrence Valley to the northern Great Plains in digital format as an aid for the numerical modelling of GIA. Data for eastern water bodies were extracted and digitized from publications during the past 120 years. Digital position coordinates were scaled from published maps of survey sites or were determined using Google Earth Pro software. Published data for paleo-lakes Duluth and Agassiz were mainly obtained from field measurements and digital elevation models. Two-sigma or 95% probability values are provided for the strandline ages and for isobase (contour) positions representing the deformed water surfaces. Peak strandline gradients reported here were largest at about ca. 13 000 years ago. Lower strandline gradients for older shores may reveal areas closer to the peripheral bulge and areas of thinner ice (lighter crustal loads). Concave upward strandline profiles characterize most paleo-basins, whereas a linear uplift profile characterizes the Champlain Sea strandline. Directions of strandline maximum uplift within the former water body basins point toward the thickest part of the LIS near the Quebec–Labrador ice dome.

Tunable Knot Segregation in Copolyelectrolyte Rings Carrying a Neutral Segment.

We use Langevin dynamics simulations to study the knotting properties of copolyelectrolyte rings carrying neutral segments. We show that by solely tuning the relative length of the neutral and charged blocks, one can achieve different combinations of knot contour position and size. Strikingly, the latter is shown to vary nonmonotonically with the length of the neutral segment; at the same time, the knot switches from being pinned at the block's edge to becoming trapped inside it. Model calculations relate both effects to the competition between two adversarial mechanisms: the energy gain of localizing one or more of the knot's essential crossings on the neutral segment and the entropic cost of such localization. Tuning the length of the neutral segment sets the balance between the two mechanisms and hence the number of localized essential crossings, which in turn modulates the knot's size. This general principle ought to be useful in more complex systems, such as multiblock copolyelectrolytes, to achieve a more granular control of topological constraints.