Rectangular Contours Research Articles

Instance Segmentation Frustum–PointPillars: A Lightweight Fusion Algorithm for Camera–LiDAR Perception in Autonomous Driving

The fusion of camera and LiDAR perception has become a research focal point in the autonomous driving field. Existing image–point cloud fusion algorithms are overly complex, and processing large amounts of 3D LiDAR point cloud data requires high computational power, which poses challenges for practical applications. To overcome the above problems, herein, we propose an Instance Segmentation Frustum (ISF)–PointPillars method. Within the framework of our method, input data are derived from both a camera and LiDAR. RGB images are processed using an enhanced 2D object detection network based on YOLOv8, thereby yielding rectangular bounding boxes and edge contours of the objects present within the scenes. Subsequently, the rectangular boxes are extended into 3D space as frustums, and the 3D points located outside them are removed. Afterward, the 2D edge contours are also extended to frustums to filter the remaining points from the preceding stage. Finally, the retained points are sent to our improved 3D object detection network based on PointPillars, and this network infers crucial information, such as object category, scale, and spatial position. In pursuit of a lightweight model, we incorporate attention modules into the 2D detector, thereby refining the focus on essential features, minimizing redundant computations, and enhancing model accuracy and efficiency. Moreover, the point filtering algorithm substantially diminishes the volume of point cloud data while concurrently reducing their dimensionality, thereby ultimately achieving lightweight 3D data. Through comparative experiments on the KITTI dataset, our method outperforms traditional approaches, achieving an average precision (AP) of 88.94% and bird’s-eye view (BEV) accuracy of 90.89% in car detection.

Automatic Vehicle Number Plate Recognition Approach Using Color Detection Technique

An Automatic Vehicle Number Plate Recognition System (AVNPR) is a key research area in image processing. Various techniques are developed and tested by researchers to improve the detection and recognition rate of AVNPR system but faced problems due to issues such as variation in format, lighting conditions, scales, and colors of number plates in different countries or states or even provinces of a country. Douglas Peucker Algorithm for shape approximation has been used in this research to detect the rectangular contours and the most prominent rectangular contour is extracted as a number plate (NP) and the connected component analysis is used to segment the characters followed by optical character recognition (OCR) to recognize the number plate characters. A custom dataset of 210 vehicle images with different colors at various distances and lighting conditions was used for the proposed method captured on my smart phone Galaxy J7 Model SM-j700F at roads and parking. The dataset contains various types of vehicles (i.e. Trucks, motorcars, mini-buses, tractors, pick-ups etc). The proposed method shows an average result of 95.5%. The novelty used in this method is that it works for different colors simultaneously because in Pakistan, several colors are used for vehicle NPs.

DESIGN AND TECHNOLOGICAL PROPOSALS FOR IMPROVING A SINGLE-PHASE TRANSFORMER WITH LAMINATED MAGNETIC CORE

Goal. The purpose of the work is to analyze the features and substantiate the advantages of the spatial radial electromagnetic system of a single-phase transformer with rectangular sections of the rods of a charged magnetic circuit. Methodology. Improvement of single-phase transformers is possible by structural-geometric transformations of active elements. The justification of the advantages of such transformations is achieved by the method of invariant objective functions with dimensionless optimization components and universal relative controlled variables. Results. Replacing the rectangular contours of the variants of a planar magnetic circuit with a hexagonal circuit leads to a decrease in the volume of steel and the loss of three angular zones of changes in the direction of the magnetic flux relative to the texture compared to planar counterparts. The separation of the windings into sections with an arrangement on three rods leads to a decrease in the average length of the coil. Originality. A three-core magnetic core can consist of rod and jugular-angular parallelogram plates of anisotropic and isotropic electrical steel. It is advisable to combine a combination of steels by integral welding of billets with subsequent separation into chevron jugular-rod elements. The method called on has developed mathematical models of the mass, cost, and active power losses of variants of a single-phase electromagnetic system of a transformer with rod and armor planar and spatial radial three-core magnetic cores. Practical significance. It was found that the decrease in the extrema of the mass and cost indicators, as well as the calculated decrease, under the condition that the coefficients of additional losses are identical, the extrema of the losses of the single-phase radial three-rod system of the transformer relative to the planar analogue with a bar stocked magnetic wire from anisotropic steel, respectively 13,0-12,3 %, 15,3-10,1 % and 15,1-18,1 % with copper windings and 10,8-10,2 %, 12,8-13,7 % and 12,6-12,3 % with aluminum windings. The main indicators of traditional single-phase systems with rod and armored magnetic circuits differ insignificantly, which is consistent with early known optimization and calculation data of transformers.

Development of methods for buildings calculation from sandwich panels for transformable low-rise buildings

This paper focuses on calculating the main loads of prefabricated low-rise buildings from sandwich panels of arbitrary structural elements and connections in the form of a rigid spatial system. The main objective of this research are the theoretical and experimental substantiation of rational parameters of quickly erected transformable low-rise buildings from sandwich panels for the development of optimal design solutions to ensure spatial rigidity. The research used empirical research method - observation, experiment, measurement, comparison and analysis. The quickly erected transformable low-rise buildings of sandwich panels, like a prismatic shell consisting in the transverse direction of two closed rectangular contours, can bear an arbitrary power load. Determination of the cost of materials for additional structural elements in the form of ties (embedded parts), combining the individual elements in a holistic design that provides spatial rigidity of the structure.

Simple derivative-free method of zero extraction by phase-based enclosure for determination of complex propagation constants in planar multilayer waveguides.

A rigorous and simple way to implement a numerical method for extracting the propagation constants and modal characteristics of lossless, lossy, and active planar multilayer waveguides is presented. The method can accurately determine the complex propagation constants of both guided and leaky modes. The method does not utilize the derivative of the dispersion function nor any integrals of it. It is based on finding the estimates of the zeros of the dispersion function by a systematic successively tighter enclosure of the zeros with exclusive use of only the phase of the dispersion function along varying rectangular contours in the complex plane. The zero estimates are then refined by Müller's iterative scheme employing deflation. The method was named derivative-free zero extraction by phase-based enclosure (DFZEPE) for brevity. The DFZEPE method has been applied to lossless, lossy, active, and antiresonant reflecting optical waveguides published in the literature and analyzed with similar methods, and the results are excellent. The proposed DFZEPE method has global convergence and can be applied to a plethora of electromagnetic (and other) problems where the zeros of an analytic function are sought.

On the readability of leaders in boundary labeling

External labeling deals with annotating features in images with labels that are placed outside of the image and are connected by curves (so-called leaders) to the corresponding features. While external labeling has been extensively investigated from a perspective of automatization, the research on its readability has been neglected. In this article, we present the first formal user study on the readability of leader types in boundary labeling, a special variant of external labeling that considers rectangular image contours. We consider the four most studied leader types (straight, L-shaped, diagonal, and S-shaped) with respect to their performance, that is, whether and how fast a viewer can assign a feature to its label and vice versa. We give a detailed analysis of the results regarding the readability of the four models and discuss their aesthetic qualities based on the users’ preference judgments and interviews. As a consequence of our experiment, we can generally recommend L-shaped leaders as the best compromise between measured task performance and subjective preference ratings, while straight and diagonal leaders received mixed ratings in the two measures. S-shaped leaders are generally not recommended from a practical point of view.

Mutual Inductance of Two Coplanar Rectangular Contours with Symmetrical Internal Arrangement

The expediency of developing expressions for mutual inductance of rectangular and square coplanar contours is caused by configuration of frame antennas typical for RFID-technologies. Expressions presented in this article are aimed at simplifying calculation of induction coefficients when designing loop antennas. Expressions for mutual inductance of rectangular coplanar contours with symmetrical internal arrangement are obtained on the basis of the method of sections. It is shown that under certain conditions the expressions obtained can be reduced to intrinsic inductances of the square and rectangular frames encountered in antenna configurations. The analysis allows to estimate regions of resonance frequencies of frame receiving antennas. Simultaneously, a comparative analysis of a number of expressions for the intrinsic inductance of rectangular and square frames is performed, and attention is drawn to the difference in estimates. Recommendations for clarifying square contour external inductance are provided.

Methods, software and datasets to verify DVH calculations against analytical values: Twenty years late(r).

The authors designed data, methods, and metrics that can serve as a standard, independent of any software package, to evaluate dose-volume histogram (DVH) calculation accuracy and detect limitations. The authors use simple geometrical objects at different orientations combined with dose grids of varying spatial resolution with linear 1D dose gradients; when combined, ground truth DVH curves can be calculated analytically in closed form to serve as the absolute standards. dicom RT structure sets containing a small sphere, cylinder, and cone were created programmatically with axial plane spacing varying from 0.2 to 3 mm. Cylinders and cones were modeled in two different orientations with respect to the IEC 1217 Y axis. The contours were designed to stringently but methodically test voxelation methods required for DVH. Synthetic RT dose files were generated with 1D linear dose gradient and with grid resolution varying from 0.4 to 3 mm. Two commercial DVH algorithms-pinnacle (Philips Radiation Oncology Systems) and PlanIQ (Sun Nuclear Corp.)-were tested against analytical values using custom, noncommercial analysis software. In Test 1, axial contour spacing was constant at 0.2 mm while dose grid resolution varied. In Tests 2 and 3, the dose grid resolution was matched to varying subsampled axial contours with spacing of 1, 2, and 3 mm, and difference analysis and metrics were employed: (1) histograms of the accuracy of various DVH parameters (total volume, Dmax, Dmin, and doses to % volume: D99, D95, D5, D1, D0.03 cm(3)) and (2) volume errors extracted along the DVH curves were generated and summarized in tabular and graphical forms. In Test 1, pinnacle produced 52 deviations (15%) while PlanIQ produced 5 (1.5%). In Test 2, pinnacle and PlanIQ differed from analytical by >3% in 93 (36%) and 18 (7%) times, respectively. Excluding Dmin and Dmax as least clinically relevant would result in 32 (15%) vs 5 (2%) scored deviations for pinnacle vs PlanIQ in Test 1, while Test 2 would yield 53 (25%) vs 17 (8%). In Test 3, statistical analyses of volume errors extracted continuously along the curves show pinnacle to have more errors and higher variability (relative to PlanIQ), primarily due to pinnacle's lack of sufficient 3D grid supersampling. Another major driver for pinnacle errors is an inconsistency in implementation of the "end-capping"; the additional volume resulting from expanding superior and inferior contours halfway to the next slice is included in the total volume calculation, but dose voxels in this expanded volume are excluded from the DVH. PlanIQ had fewer deviations, and most were associated with a rotated cylinder modeled by rectangular axial contours; for coarser axial spacing, the limited number of cross-sectional rectangles hinders the ability to render the true structure volume. The method is applicable to any DVH-calculating software capable of importing dicom RT structure set and dose objects (the authors' examples are available for download). It includes a collection of tests that probe the design of the DVH algorithm, measure its accuracy, and identify failure modes. Merits and applicability of each test are discussed.

SU‐E‐T‐689: Semi‐Automated GPU‐Based Monte Carlo Dose Calculation for Total Body Irradiation

Purpose:To enable fast and accurate TBI dose calculations for research and clinical applications.Methods:We adapted GPU‐based Monte Carlo (MC) dose calculation library written for patient specific IMRT quality assurance to enable us to compute dose delivered to a patient during total body irradiation (TBI). The full CT dataset of the patient is loaded into the system along with organ contours, specifically, the body and lung contours, as well as rectangular contours denoting compensator sizes and locations. The CT data is automatically cropped by setting all values outside of the body contour to air HU value. The lung and compensator contours are automatically voxelized, projected and rotated by 45 degrees onto the 40×40 cm fluence map plane and weighted by the appropriate attenuation value. The mirror image of the fluence map is also computed for the opposite beam configuration (P‐A for A‐P, or R‐L for L‐R). The fluence maps are then included as input, along with the auto‐segmented material types and density values from the CT dataset, into the GPU‐based MC calculation. The Result is the full body MC calculated TBI dose for the patient which can then be used for various research studies. The users upload their data to the GPU server using FTP. The interface to the calculation software is in the form of an iPython Notebook, enabling the user to access the GPU server through a common web browser to input various parameters, monitor the process, and analyze results.Results:The developed software enables researchers and clinicians to compute MC TBI dose results in less than 2 minutes given lung and body contours and compensator transmission coefficients.Conclusion:We successfully designed and developed a semi‐automated MC TBI dose calculation software to enable research and clinical studies.

Solving three-body-breakup problems with outgoing-flux asymptotic conditions

An analytically solvable three-body collision system ($s$ wave) model is used to test two different theoretical methods. The first one is a configuration interaction expansion of the scattering wave function using a basis set of Generalized Sturmian Functions (GSF) with purely outgoing flux (CISF), introduced recently in A. L. Frapicinni, J. M. Randazzo, G. Gasaneo, and F. D. Colavecchia [J. Phys. B: At. Mol. Opt. Phys. 43, 101001 (2010)]. The second one is a finite element method (FEM) calculation performed with a commercial code. Both methods are employed to analyze different ways of modeling the asymptotic behavior of the wave function in finite computational domains. The asymptotes can be simulated very accurately by choosing hyperspherical or rectangular contours with the FEM software. In contrast, the CISF method can be defined both in an infinite domain or within a confined region in space. We found that the hyperspherical (rectangular) FEM calculation and the infinite domain (confined) CISF evaluation are equivalent. Finally, we apply these models to the Temkin-Poet approach of hydrogen ionization.

Classification of the Female Hairline and Refined Hairline Correction Techniques for Asian Women

Hair transplantation has been a highly effective technique in reducing wide foreheads and recontouring the hairline. To classify hairline contour in Asian women and to find a way to make an ideal and refined female hairline. The hairline contours of 234 female volunteers were classified into five groups. We measured the height and width of foreheads and maximal depth of the infratemporal portion. We also performed hairline correction on 350 female patients with a wide forehead with an M-shaped hairline. Hairlines of the volunteers were grouped as round (27.35%), M-shaped (28.20%), rectangular (27.35%), bell-shaped (10.25%), or triangular (2.99%). The average height of the forehead was 6.38±0.89 cm, average width of the forehead 14.30±1.75 cm, and maximal depth of the infratemporal portion 4.29±0.77 cm. In 350 patients operated on, the average area of the frontotemporal recess was 30.1 cm(2), and approximately 1,054 follicular units (FU) were needed. The classification of Asian female hairlines and our refined techniques will be beneficial for correcting wide foreheads with M-shaped or rectangular hairline contours.

An Experimental Study on the Elastic–Plastic Fracture in a Ductile Material under Mixed‐Mode Loading

Abstract: Stereo vision was used to measure the crack‐tip parameters, such as J integral, plastic mixity and elastic mixity of mixed‐mode fracture specimens, and to study the applicability of the Shih's plane strain solution to the mixed‐mode crack‐tip fields. The fracture specimen used in this study was a compact tension shear (CTS) specimen made of 2024‐O aluminum. The in‐plane strain and stress fields near the mixed‐mode crack tip of the CTS specimen were determined using the deformation field measured by the stereo vision. It is observed that the J integral values computed along rectangular contours surrounding the mixed‐mode crack‐tip approach constant values after r/h > 0.5. The in‐plane strains determined experimentally at several points near the crack tip and at several radial lines emerging from the crack tip are compared with the values calculated using Shih's plane‐strain solution and the HRR slope, named after the investigations of Hutchinson, Rice and Rosengren respectively. It is found that the measured values follow the trends of the Shih's plane‐strain solution. The elastic mixity evaluated using the measured crack‐tip stress fields is close to that obtained from analytical solution. However, the evaluated plastic mixity deviates from the analytical solution.

Convex Grid Drawings of Plane Graphs with Rectangular Contours

Convex Grid Drawings of Plane Graphs with Rectangular Contours

Resonant modes in continuous metallic grids over ground and related spatial-filtering applications

We use the theory of periodic structures, full-wave electromagnetic, and microwave circuit simulations to explain the resonant modes that propagate in metallic grids having rectangular unit cells constructed over a ground plane. We show that these metallic grids can support two types of resonant modes that have rectangular and hyperbolic isofrequency dispersion contours. By exploiting the spatial dispersion properties of these modes, a microwave 3GHz∕6GHz harmonic splitter and a highly selective 5.8GHz∕6.2GHz diplexer are designed and simulated. Furthermore, we provide experimental results for the diplexer and for the harmonic splitter, synthesized in microstrip technology. The proposed metallic grids utilize continuous unloaded transmission-line segments thus leading to spatial-filtering devices that are easy to fabricate and are scalable to terahertz frequencies and beyond.

Convex Grid Drawings of Plane Graphs with Rectangular Contours

Convex Grid Drawings of Plane Graphs with Rectangular Contours

Molecularly Resolved Dynamics for Two-Dimensional Nucleation of Supramolecular Assembly

Nucleation growth of a platinum porphyrin derivative adsorbed on a Cu (100) surface was observed with a scanning tunneling microscope. The molecule attached with four di-tert-butylphenyl groups allowed equilibrium between diffusional gas phase and two-dimensional nuclei. To minimize the free energy for nucleation, the registry of the molecules into the kink sites resulted in formation of nuclei with singular, rectangular contours. Dependence of the equilibrium conditions on the sample-tip bias voltages was also presented.

Fuzzy shell clustering algorithms in image processing: fuzzy C-rectangular and 2-rectangular shells

Objective function-based clustering has been generalized recently to detect contours of circles and ellipses or even hyperbolas in a set of binary data vectors. Although there are special algorithms to discover lines, the detection of rectangles needs further treatment. A simple line-detection algorithm is not sufficient for rectangles since for identifying four lines as one rectangle, additional information such as the length of the lines and whether they are parallel or meet at a right angle is necessary. In this paper, a special fuzzy shell-clustering algorithm for rectangular contours is developed. The principal idea behind it can be generalized for other polygons so we also derive an algorithm that is capable of detecting rectangles and other polygons as well as approximating circles, ellipses, and lines.

An exact solution to the plane orthotropic elasticity problem with rectangular boundaries under arbitrary edge forces

Mathieu’s approach to the fundamental problem of plane strain with rectangular boundaries was futher developed by Baker, Pavlovic and Tahan. The method consists in breaking up the full solution into eight basic problem types. In this paper, an exact solution to two-dimensional orthotropic elasticity problems with rectangular contours is obtained. Some convergent results are proved.

Application of the [formula omitted] integral to mixed mode crack problems for anisotropic composite laminates

The J k integral method for determining mixed mode stress intensity factors separately in the cracked anisotropic plate is developed. Stress intensity factors are indirectly determined from the value of J 1 and J 2 . The J 2 integral can be evaluated efficiently from a finite element solution, neglecting the contribution from the portion of the integration contour along the crack faces, by selecting the integration contour in the vicinity of the crack tip. Using functions of a complex variable, the complete relations between J 1 , J 2 and K I , K II for anisotropic materials are derived conveniently by selecting narrow rectangular contours shrinking to the crack tip. Compared to the existing path independent integral methods, the present method does not involve calculating the auxiliary solution and hence numerical procedures become quite simple. Numerical results to various propblems are given and demonstrate the accuracy, stability and versatility of the method.

J-Estimation Procedure Based on Moire Interferometry Data

The accuracy of the approximate J-estimation procedure evaluated along rectangular contours in the elastic and the HRR crack tip fields was assessed. The path independency of the approximate J’s in the presence of LEFM and elastic-plastic stress fields was demonstrated experimentally in 7075-T6, 2024-0 and 5052–H32 SEN specimens with small stable crack growth of 1 to 2 mm. HRR field does not exist in a ductile material with relatively large strain-hardening exponent, i.e., N = 15. The approximate J and the COD resistance curves for 2024-0 and 5052-H32 specimens for small crack extension was established. These curves showed little sensitivity to the notch tip acuity due to large plastic yielding.