Corner Angle Research Articles

Rapid Prediction and Parameter Evaluation of Process-Induced Deformation in L-Shape Structures Based on Feature Selection and Artificial Neural Networks

The process-induced deformation (PID) during the manufacturing of thermosetting composite materials can significantly compromise manufacturing precision. This paper introduces an innovative method that combines a finite element analysis (FEA), feature classification algorithms, and an Artificial Neural Network (ANN) framework to rapidly predict the PID of a typical L-shaped structure. Initially, a comprehensive range of parameters that influence PID are compiled in this research, followed by the generation of a dataset through FEA considering viscoelastic constitutive models, validated by experimental results. Influential parameters are classified using Random Forest and LASSO regression methods, with each parameter rated according to its impact on PID, delineating their varying degrees of importance. Subsequently, through a hyperparameter analysis, an ANN framework is developed to rapidly predict the PID, while also refining the assessment of the parameters’ significance. This innovative approach achieves a computational time reduction of 98% with less than a 5% loss in accuracy, and highlights that under limited computational conditions, considering only a subset or all of the parameters—the peak temperature, corner angle, coefficient of chemical shrinkage, coefficient of thermal expansion, curing pressure, and E1—minimizes accuracy loss. The study demonstrates that machine learning algorithms can effectively address the challenge of predicting composite material PID, providing valuable insights for practical manufacturing applications.

Study on the propagation characteristics of shockwave in dense crowd in corner passage

Crowd shockwaves are prone to occur when evacuating dense crowds, especially in areas with corner passages, leading to congestion and accidents. The characteristics of shockwaves in corner passages need further exploration. This study used AnyLogic software based on the social force model to construct scenarios. The propagation mechanism of crowd shockwaves was revealed through simulation analysis of the changes in wave amplitude, duration, and propagation velocity of crowd density waves under different corner angles (0–90°). It was found that a 45° corner passage has advantages compared to other corner passages for evacuation. At higher desired velocities, pedestrians form a bottleneck-like area at the corner of the passage, resulting in crowd shockwaves. Because of social forces, congestion occurs primarily in the corner area. To alleviate this pressure, pedestrians actively adjust the distance between themselves and others. The time interval between the two shockwaves decreases as the desired velocity increases. The propagation time of crowd shockwaves before the corner is generally more significant than the duration after the corner. This study could guide the elimination or reduction of crowd shockwaves, improving pedestrians' evacuation efficiency and safety in evacuation passages.

Controllably Constructing morphology and structure of potassium chloride crystal by green supersaturation modulation

Controllable and green construction of morphology and structure in potassium chloride (KCl) crystals is necessary in the fields of pharmaceuticals, catalysis, minerals, and jewels design. Here, the work presented a lucid way for preparing KCl crystal with various morphology including hopper-, sphere- and hollow cube-like structure through green supersaturation modulation. Parameters including stirring speed, cooling range, cooling rate, and excess inorganic composing ions influenced the growth kinetics of hopper KCl crystal as well as the surficial morphology and structure: (1) Metastable region and stable conditions were beneficial for uniform growth of crystal; (2) Small size of crystal particles were obtained with high shear force; (3) Corner angle of crystal would be abraded in slow cooling rate; (4) Non-uniform crystal appeared in improper cooling range condition; (5) Additional composing ions might introduce deformed structure according to the basic crystal repeating unit with corresponding elements. Based on the above study of growth kinetics, hopper-, sphere- and hollow cube-like crystal were obtained. The morphology and structure properties of various crystal were researched by three-dimensional visualization, X-ray diffraction (XRD), and scanning electron microscope (SEM) for optimized application such as higher exposing surface area of hopper-like crystal than original cubic crystal. The main exposed faces for smooth cubic, hollow cubic, and hopper structure exhibited were (200), (220), and (400) facet, respectively, which could be a consequence of the inner beveling. Surface of spherical structure was a circular arc with relative high roughness, being ascribed to the formation mechanism of spherical structure from cubic structure. Therefore, the work presented a strategy to controllably design KCl crystal with different structure and morphology in a green way.

Shear performance of FRP panel-reinforced rc columns attached using corner angles and bolts without epoxy resin

As the frequency of earthquakes has risen globally, the importance of seismic design in building construction has intensified. Fiber-reinforced polymers (FRP) are increasingly utilized as seismic reinforcement materials for reinforced concrete (RC) columns because of their lighter weight and superior strength compared to concrete and steel. However, the epoxy resin commonly used for FRP reinforcement is susceptible to fire, as it exhibits a glass transition temperature below 100 °C, and its performance can vary depending on the skill of the applicator. A method was therefore proposed to involve the non-adhesive application of FRP panels using corner angles and angle connections, eliminating the need for epoxy resin. Experimental and analytical studies were conducted to assess the shear performance of FRP-reinforced RC columns without adhesive attachment. The findings revealed that the maximum shear force capacity increased by more than 1.5 times compared to traditional RC columns. By securing the corner angle and FRP panel with angle connection materials, the attachment effect can be maximized to the extent of the corner angle area, suggesting its potential for enhancing shear performance.

Local Well-Posedness of the Nonlinear Wave System Near a Space Corner of Right Angle

Local Well-Posedness of the Nonlinear Wave System Near a Space Corner of Right Angle

Multi-area collision-free path planning and efficient task scheduling optimization for autonomous agricultural robots

Collision-free path planning and task scheduling optimization in multi-region operations of autonomous agricultural robots present a complex coupled problem. In addition to considering task access sequences and collision-free path planning, multiple factors such as task priorities, terrain complexity of farmland, and robot energy consumption must be comprehensively addressed. This study aims to explore a hierarchical decoupling approach to tackle the challenges of multi-region path planning. Firstly, we conduct path planning based on the A* algorithm to traverse paths for all tasks and obtain multi-region connected paths. Throughout this process, factors such as path length, turning points, and corner angles are thoroughly considered, and a cost matrix is constructed for subsequent optimization processes. Secondly, we reformulate the multi-region path planning problem into a discrete optimization problem and employ genetic algorithms to optimize the task sequence, thus identifying the optimal task execution order under energy constraints. We finally validate the feasibility of the multi-task planning algorithm proposed by conducting experiments in an open environment, a narrow environment and a large-scale environment. Experimental results demonstrate the method's capability to find feasible collision-free and cost-optimal task access paths in diverse and complex multi-region planning scenarios.

A numerical study of Elasto-inertial particle-focusing in straight and serpentine microchannels

Microfluidic devices have gained popularity in recent years due to their low cost and simplicity. Cell focusing linked with cell counting and cell separation used in clinical tests and point-of-care devices stands towards the top of every list of microfluidic applications. To focus and manipulate particles in a Newtonian medium, inertial microfluidics has been widely used. There is a requirement to replace a significantly more efficient approach given various particle-focusing positions near the channel walls recorded by inertial microfluidics. Here, the synergetic effect of elastic and inertial forces in relatively low-concentration viscoelastic fluids was investigated numerically. Utilizing particle-focusing behavior in straight and serpentine channels with different corner angles, by applying the numerical results obtained using the developed direct numerical simulation method (DNS) for elastic and inertial forces, we created a microchannel with a remarkable performance. As the flow regime transitions to elasto-inertial, where inertial forces are comparable to elastic forces in a straight microchannel, particles tend to concentrate at the channel centerline. As the flow rate increases, however, particle defocusing develops, and shear gradient lift forces ultimately overcome elastic forces in the channel's central region. Given that fluid flows at a higher velocity in the serpentine channel with a corner angle of 75° than in other channels, the Dean drag force induced by secondary flow serves to reduce particle defocusing rate at a given flow rate, making this channel a desirable platform for Elasto-inertial microfluidics. Particle focusing in a vertical direction was noticed as a benefit of elasto-inertial microfluidics, regardless of the geometry or flow rate of the particles passing through the channel. Finally, the impact of particle diameter on focusing behavior was studied. As particle diameter decreases, focusing width decreases and the focusing band shifts to the left side of the cross-section. We expect that the numerical evaluation of using viscoelastic medium in complex geometries can contribute to accelerate the three dimensional particle-focusing mechanism and enhance the efficiency of microdevices for cell and particle manipulation.

Fiber bundle deposition model and variable speed printing strategy for in-situ impregnation 3D printing of continuous fiber reinforced thermoplastic composites

In the in-situ impregnation 3D printing of continuous fiber reinforced thermoplastic composites (CFRTPCs) at constant printing speed, in order to pursue higher printing efficiency, a higher speed for printing is adopted generally, which has no effect on the printing of the straight section, but at the same speed of printing at the corner, the printing speed will cause the fiber bundle to deviate from the printing path at the corner, which affects the accurate laying of fiber bundle along the printing path. Obviously, reducing the printing speed is an effective method to improve the print quality at the turn, but printing the entire part at the reduced speed will greatly limit the overall printing speed. However, the problem of different corner angles and shifting points from the straight section of high-speed printing to the corner section of low-speed printing has been puzzling researchers. In this paper, a fiber bundle deposition model has been proposed to reveal the deposition of fiber bundles, and the maximum offsets of fiber bundles were predicted under different turning angles. Compared with the measured results, the prediction error at different turning angles ranged from −1.07 % to 10.30 %. Then, combining with the finite element analysis method, the fiber bundle deposition model was adopted to study the effects of printing speeds, and the maximum printing speeds for different printing angles and the variable printing speed strategy have been put forward. The results have revealed that, by using the optimized variable printing speed strategy, the surface quality of the fabricated parts and the deposition of the fiber bundles along the designed printing path were significantly improved. The fiber bundle deposition model and the variable speed printing strategy could be helpful for the high-precision 3D printing of CFRTPCs.

Enhancing Bangladeshi License Plate Recognition: A YOLOv8 Approach with Roboflow Integration for Accuracy and Speed Optimization

Abstract: Automatic License Plate Recognition (ALPR) systems are indispensable in modern transportation services, offering crucial benefits in traffic management, parking, toll collection, and surveillance. However, implementing ALPR in Bangladesh presents challenges due to the intricacies of Bangla characters and low-resolution CCTV images. Despite ALPR's potential to enhance safety and security, issues such as license plate variations and image quality hinder its effective implementation. This research addresses these challenges by developing a customized YOLOv8 model tailored for recognizing Bengali license plates, with a focus on precise localization, character segmentation, and script deciphering. Leveraging advanced deep learning techniques, the study aims to enhance efficiency and accuracy for applications in law enforcement and traffic management. Through a comprehensive workflow integrating Roboflow and YOLOv8, effective dataset collection, annotation, augmentation, and model training are demonstrated. System evaluation on diverse test datasets confirms the reliable detection and recognition of Bangladeshi license plates, underscoring the model's practical utility and robustness in real-world scenarios. Additionally, the research showcases notable advancements in ALPR technology specific to Bangladesh's unique context. Noteworthy is the model's exceptional performance in detecting license plates from corner angles, even across various vehicle types, as well as its ability to accurately identify plates amid challenging conditions such as broken or obscured plates and low-resolution images. Moreover, the system's proficiency in scenarios with multiple license plates, like those on buses adorned with banners, contributes significantly to improved road safety and traffic management.

9-point Injection Technique for Lip Augmentation and Lip Corner Lifting Using Sonographic Imaging of the Labial Artery Pathway.

As lip enhancement with fillers has grown in popularity, practitioners have sought to identify injection methods that achieve aesthetically pleasing results while avoiding adverse events such as arterial injury due to intravascular injection. The primary objective of this study was to establish a safe injection technique for creating appealing, proportionate, and aesthetically pleasing lips while elevating the lip corners with filler. Before injection, the locations of the superior and inferior labial arteries were established by sonography and a 9-point injection technique (9-PIT) was devised to reliably achieve fashionable lips. Particle hyaluronic acid filler was administered to 50 patients by the 9-PIT and these patients were monitored for 3 months. The extent of lip corner elevation and the angle of lip corners were quantified by 3-dimensional analysis, while changes in the length and curvature along the upper peristomal lines were evaluated after 1 week. The superior and inferior labial arteries originated from the deep lateral aspect of the lip and gradually traversed toward the midline in the superficial layer. Superficial arterial branches were identified in the submucosal layer near the midline. All patients expressed satisfaction with the lip shaping and corner elevation, without any adverse effects or vascular complications. The angle of lip corners decreased by 8.80%, and lip corners were lifted by 1.02 mm. The upper lip exhibited a more pronounced S-shape, with the upper lip line being elongated by 6.5%. This accentuated S-shape contributed to the appearance of lifted lip corners. The 9-PIT facilitated safe and aesthetically pleasing lip volumization with corner elevation in a consistent manner, while elucidating vascular pathways. Lip corner elevation was achieved solely using HA filler.

Study on the aerodynamic characteristics and flow mechanism of square cylinders with rounded corners

In order to elucidate the variation patterns of the aerodynamic characteristics of square cylinders with rounded corners with respect to corner radius ratio and angles of incidence, and to reveal their underlying mechanisms, a wind tunnel test was performed to examine the surface wind pressure of square cylinders with a corner radius ratio R/D (where R represents the corner radius and D signifies the characteristic dimension of the object) of 0, 0.1, 0.2, 0.3, and 0.4. The experiment was conducted at a Reynolds number of 120,000 while varying the angles of incidence between 0° and 45°. In this study, aerodynamic forces, Strouhal numbers, and wind pressure were analyzed. Additionally, the flow field was visualized using a large eddy simulation (LES). The results indicate that the critical angle of incidence αcr of square cylinders with rounded corners decreases as the corner radius ratio increases. αcr represents the angle at which the mean drag and fluctuating lift are minimum and the mean lift and Strouhal number are maximum. Significant negative pressure is observed near the windward rounded corner of the square cylinders with rounded corners in the vicinity of αcr, with the highest value occurring at an R/D of 0.2. Fluctuating wind pressures could attain larger values in the vicinity of the leeward rounded corners where α = 12.5°∼20° and α = 45°. Increasing R/D to a certain value significantly alters the flow structure compared to a square cylinder with R/D= 0. This is due to the shear layer flowing close to the wall, as it does not separate at the windward rounded corner.

Corner cutting accuracy for thin-walled CFRPC parts using HS-WEDM

Carbon Fiber-Reinforced polymer (CFRP) composite parts with thin-walled corners are in great demand in aircraft, cars, and precision instruments. Nonetheless, the fabrication of these parts is difficult due to their low stiffness. High-speed WEDM is an advanced technique for cutting thin CFRP components as it is a non-contact method for removing materials. Nonetheless, testing results demonstrate an unavoidable deformation in the thin-walled corners of the CFRP composite. The objective of this study is to improve the accuracy of corners in thin-walled CFRP composite parts. The research utilized a Taguchi L16 orthogonal array to investigate the influence of various process parameters, including pulse-on duration (Pon), pulse-off duration (Poff), and input current (I), as well as the parameter CFRP plate thickness (T), on corner inaccuracy. The CFRP thickness varied between 0.5, 1.0, 1.5, and 2.0 mm, and the corner angles examined were 30°, 60°, 90°, and 120°. Additionally, a second-order polynomial regression model was used to determine the correlation between the process parameters and corner inaccuracy at various corner angles. Also, a multi-response optimization technique using a composite desirability coupled with a generalized reduced gradient were used to find the optimal process combination across various CFRP thicknesses. According to the research findings, the most relevant process parameters impacting corner accuracy at different angles were the pulse-on duration and input current. To achieve accurate corners with different angles, the optimal process parameters were identified: Pon (40µs), Poff (15µs), and I (4A) for CFRP thicknesses 0.5 and 1.0mm, and Pon (45μs), Poff (30μs), and I (2A) for thicknesses 1.5 and 2.0mm.

Subicular neurons encode concave and convex geometries

Animals in the natural world constantly encounter geometrically complex landscapes. Successful navigation requires that they understand geometric features of these landscapes, including boundaries, landmarks, corners and curved areas, all of which collectively define the geometry of the environment1–12. Crucial to the reconstruction of the geometric layout of natural environments are concave and convex features, such as corners and protrusions. However, the neural substrates that could underlie the perception of concavity and convexity in the environment remain elusive. Here we show that the dorsal subiculum contains neurons that encode corners across environmental geometries in an allocentric reference frame. Using longitudinal calcium imaging in freely behaving mice, we find that corner cells tune their activity to reflect the geometric properties of corners, including corner angles, wall height and the degree of wall intersection. A separate population of subicular neurons encode convex corners of both larger environments and discrete objects. Both corner cells are non-overlapping with the population of subicular neurons that encode environmental boundaries. Furthermore, corner cells that encode concave or convex corners generalize their activity such that they respond, respectively, to concave or convex curvatures within an environment. Together, our findings suggest that the subiculum contains the geometric information needed to reconstruct the shape and layout of naturalistic spatial environments.

Bead geometry prediction and optimization for corner structures in directed energy deposition using machine learning

Wire Arc Additive Manufacturing as a Directed Energy Deposition technology has disruptive potential for modern manufacturing. The technology comes with the flexibility and material efficiency of additive manufacturing processes while mitigating the disadvantages through high material deposition rates and high energy efficiency. However, the prevalence of the technology is inhibited by its geometrical inaccuracy and the large induced residual stresses. This work tackles the former problem by capturing the process parameter-geometry relationship using Machine Learning. To do so, multiple mild steel welding beads with varying shape features like corner angles are printed using a Metal Inert Gas welding machine attached to an industrial robot. The cross-sectional profile of the printed beads is measured using a point laser sensor and correlated through a Multilayer Perceptron to input features such as travel speed, wire feed speed, and shape features. By incorporating varying corner angles, a holistic model, not limited to geometry prediction of straight beads only, is trained. Using the model, excess material at the inner angle of corners determined by the overlapping regions of the two adjacent beads can be predicted. By generating a database of possible bead shapes an inverse algorithm that suggests welding parameter combinations that yield a smooth bead shape at the corner is created, thus enabling improvement of the overall accuracy of the Wire Arc Additive Manufacturing process.

Investigation on the effect of corner error in WEDM taper cutting process of Ti–6Al–4V

ABSTRACT Wire Electrical Discharge Machining (WEDM) is a non-conventional manufacturing method known for producing high-quality surface finishes and relies on the condition that materials conduct electricity. However, corner inaccuracies arise in workpieces during corner cuts with this method. This study aims to investigate corner inaccuracies using a novel approach involving oblique cutting and considering parameters such as wire tension (WT), corner angle, taper ratio, nozzle gap, and dielectric flow rate (LQ). The lower and upper corners resulting from taper cutting are analyzed separately. Initially, the parameters were determined, and the experimental design was established using the Taguchi method. Subsequently, the Coordinate Measuring Machine (CMM) was employed to determine the point positions of the specimens. A unique software-based method was then utilized to analyze the obtained point positions, revealing deficiencies in the expected corner areas and exposing errors. Ultimately, the analysis of the results was conducted employing the ANOVA method, offering insights into the verification and outcomes of the conducted experiments. The study concludes that, when examining corner inaccuracies, the most influential parameters are wire tension and dielectric flow rate for both lower and upper corners in taper cutting.

Computational study of shock diffraction over convex edges

Numerical analysis of normal shock diffraction over various step corners is presented using an implicit second-order upwind least squares cell-based method. Slipstream angle calculation for various corner angles and Mach numbers, variation of pressure load and specific heat flux with incident shock Mach numbers and different step corners along the step wall, separation point movement, and reattachment of the streamlines are some of the key features of the present study. Detailed studies have been conducted about the perturbed region enclosed within the diffracted shock wave and the last running expansion wave with the increase in the incident shock Mach numbers. The finite Volume Method is used to solve the governing equations numerically for the simulation of the moving shock. Various flow characteristics such as secondary shock, contact surface, expansion wave, slipstream, vortex, etc are well captured. Apart from isopycnics; Mach contours, isobars, and isotherms are plotted as well. The reattachment region formed after the flow separation near the step edge is mentioned and corresponding lengths over various steps are presented. Separation point movement along the step wall is highlighted and a relevant increase in reattachment length is reported. The slipstream angles get increased with incident shock Mach numbers and with corner angles. However, the rate of increment of slipstream angle decreases gradually. The core of the vortices generated and the reattachment of the separated streamlines are indicated by the two downfalls in the heat flux values.

Subduction Initiation at the Corner of Small Oceanic Basins

AbstractIn Southeast Asia, emerging subduction zones often appear to begin at the corners of small oceanic basins, which have a triangular‐indenter continent–ocean boundary geometry. To investigate the influence of a triangular corner on subduction initiation, we performed a series of three‐dimensional numerical simulations with varying corner angles and base lengths. The results show that the apex of the corner constitutes the initial location of subduction, irrespective of the angle or the extent of the corner. Smaller angle corners are more likely to facilitate subduction initiation. At the same time, wide acute angle corners are difficult to form. Our findings suggest that triangular corner structures may facilitate subduction initiation in smaller basins; however, the role such corners in subduction initiation is limited in larger basins. Our results emphasize the importance of accounting for the three‐dimensional geometry of a subduction zone when examining its subduction dynamics and geological features.

Inverse asymptotic treatment: Capturing discontinuities in fluid flows via equation modification

A major challenge in developing accurate and robust numerical solutions to multi-physics problems is to correctly model evolving discontinuities in field quantities. These manifest themselves as interfaces between different phases in multi-phase flows, or as shock and contact discontinuities in (either single- or multi-phase) compressible flows. A plethora of bespoke discretization schemes have been developed to capture both types of discontinuities in physics-based simulations. However, when a quick response is required to rapidly emerging challenges such as the need to design novel hypersonic vehicles, the complexity of such implementations impedes a swift transition from problem formulation to computation. This is exacerbated by the need to compose multiple interacting physics, which may cause specialized schemes to break unexpectedly as governing equations need to be changed and/or added. We introduce “inverse asymptotic treatment” (IAT) as a unified framework for capturing discontinuities in fluid flows that enables building directly computable models based on standard, off-the-shelf numerics. By capturing discontinuities through modifications at the level of the governing equations, rather than via reliance on specialized discretization schemes, IAT can seemlessly handle additional physics and thus makes it easier for novice end users to quickly obtain numerical results for a variety of multi-physics scenarios. This strategy also facilitates the use of a “multi-physics” compiler that automates the conversion of the modified PDEs to numerical source code readable by popular computational frameworks like OpenFOAM. We outline IAT in the context of phase-field modeling of two-phase incompressible flows, and then demonstrate its generality by showing how localized artificial diffusivity (LAD) methods for single-phase compressible flows can be viewed as instances of IAT. Through the real-world example of a laminar hypersonic compression corner, we illustrate IAT’s ability to, within a span of just a few months, generate a directly computable model whose wall metrics predictions for sufficiently small corner angles come close to that of NASA’s state-of-the-art VULCAN-CFD solver. Finally, we propose a novel LAD approach via “reverse-engineered” PDE modifications, inspired by total variation diminishing (TVD) flux limiters, to eliminate the problem-dependent parameter tuning that plagues traditional LAD. Through canonical numerical tests, we demonstrate that this “limiter-inspired” LAD approach, when combined with second-order central differencing, can robustly and accurately model compressible flows.

Local wellposedness for the free boundary incompressible Euler equations with interfaces that exhibit cusps and corners of nonconstant angle

We prove that free boundary incompressible Euler equations are locally well posed in a class of solutions in which the interfaces can exhibit corners and cusps. Contrary to what happens in all the previously known non-C1 water waves, the angle of these crests can change in time.

Characterisation of print path deviation in material extrusion

Material extrusion, also known as fused filament fabrication, is one of the most popular additive manufacturing techniques due to its lower cost and ease of handling. However, parts produced by material extrusion have relatively poor mechanical performance, dimensional accuracy and thermal performance as compared to parts produced by subtractive manufacturing due to high void content. Previous studies have suggested print path deviation as the cause of these voids, but no attempt has yet been made to characterise these deviations. In this study, we propose a method to assess print path deviation for material extrusion that may reduce the formation of voids in printed parts. Geometric features including straight paths, various angled corners and curves of varying radii are printed at different print speeds using an open-source printer and then imaged under a microscopic. The deviation in print path centroid and width is classified as being a combination of systematic and stochastic deviations. Systematic deviation is determined by the difference between the mean of the actual print path and the ideal print path sent to the printer by the user. Stochastic deviation represents the randomness across print samples and is given by the root mean square deviation. The relationship between stochastic deviation between any two points along the print path is determined by a correlation coefficient. The results show that both print speed and different geometric print features affect the amount of deviation in the print path. In the case of correlation of the stochastic deviation along print paths, geometric features are found to have a much greater effect than print speed. The proposed method provides a low cost and highly transferrable technique to characterise the print path deviation within material extrusion parts with respect to varying printing parameters. An accurate understanding of local print deviations within a part plays a major role in the analysis and topology optimisation of 3D printed parts and gives the ability to assess the print quality and identify the root cause of print deviations, thus reducing voids and improving mechanical performance, dimensional accuracy and thermal properties of the printed part.