Corner Structures Research Articles

Corner structure optimisation design of billet mould tube for Q235 with high casting speed

Reasonable corner design of the mould is conducive to the uniform heat transfer of the billet, especially for the crack-sensitive steel such as Q235 under high casting speed. Based on the Ansys finite element analysis platform, three kinds of mould corner configurations were designed in this study, and the temperature and stress distribution of the billet and mould corresponding to different mould were compared and analysed. The results show that the cooling uniformity of the C-type mould (petal-type) was better than that of other corner configurations, the maximum temperature at the mould corner was reduced by 43.66 °C, the minimum temperature at the billet corner was increased by 109.73 °C, and the maximum Von-Mises equivalent stress at the corner of the billet was reduced by 28.09 MPa. Therefore, the C-type mould can further improve the quality of the billet and is conducive to the improvement of production efficiency.

The Effect of Corner Structure on the Optimisation of Fishable Flow Field in Aquaculture Tanks

As coastal waters face constraints such as the deterioration of the aquaculture environment and limitations on the scale of operation, aquaculture will move towards the deep and distant sea. Large-scale aquaculture vessels are a new method of deep-sea aquaculture, and improving the utilisation efficiency of aquaculture tanks to ensure the best growth conditions for fish inside while ensuring the efficient discharge of particulate matter in these tanks will affect the productivity of aquaculture and the profitability of aquaculture vessels. This study investigated the effects of the tank structure ratio on the flow field characteristics and particulate removal efficiency in the aquaculture tanks of an aquaculture vessel. Numerical simulations of the flow field characteristics in the aquaculture tanks of an 8000 t-class aquaculture vessel at anchor were conducted using the FLOW-3D software to quantitatively evaluate the effects of the corner ratio on the fishability of aquaculture tanks and the efficiency of particulate emission using the parameters related to flow velocity, turbulence intensity, capacity utilisation rate, and particulate removal efficiency. The simulation results show that the tanks with corner structures have better flow field characteristics, which include a higher flow velocity, turbulence intensity, and discharge effect. When the corner length is more than 1/3 of the tank length, increasing the corner distance does not significantly enhance the optimisation of the flow field characteristics in the tank. Overall, this study’s results provide a reference basis for the structural design and optimisation of aquaculture tanks in aquaculture vessels.

Active manipulation for Goos-Hänchen shift of guided-wave via a metasurface of silicon-nanoscale semi-spheres on SOI waveguide

Goos-Hänchen shift of total internal reflection (TIR) is the light beam movement without external driving, so envisioned to have potential manipulation of optical beams. In this article, with a silicon-on-insulator (SOI) waveguide corner structure, a variable equivalent permittivity of guided wave is modelled, and then the equivalent electric polarizabilities and the Goos-Hänchen shift of guided wave are modelled. Consequently, with a 2.0-µm SOI waveguide corner structure and an abrupt phase change of ∼0.5π caused by a vertically inserted metasurface of nanoscale semi-spheres having a 450-nm radius can reach the GH shifts of 2.1 µm for TE- and TM-mode, respectively, which are verified by both the FDTD simulation results of 1.93 µm with a reflectivity of about 62% and the experimental results of 2.0 µm with ∼60%. Therefore, this work has efficiently modelled the optical feature response of semi-sphere metasurface to guided wave and the active manipulation for the GH shifts of guided-wave, opening more opportunities to develop the new functionalities and devices for Si-based photonic integrated circuit (PIC) applications.

Fabrication of sustainable anti-icing metal surface with micro-nano composite concave angle structure by laser-electrodeposition-chemical method

Icing has adverse effects on human daily life and industrial production. The superhydrophobic surfaces have enormous potential for anti-icing applications because of the excellent water repellent effect. To enhance the anti-icing properties of metal surfaces, a hybrid method was employed, which combined laser processing, electrodeposition, and chemical soaking. This method was used to create a superhydrophobic surface with regular micro-nano composite concave corner structures on the surfaces of 7075 aluminum alloy. The morphology and wetting performance of samples under different current densities and deposition times were characterized. Under the current density of 40 mA/cm2 and the deposition time of 300 s, the hydrophobic performance of the prepared ZnNi alloy superhydrophobic coating was optimal. During the anti-frost testing, the prepared superhydrophobic surface only experienced water droplet aggregation, while frost never appeared. Compared to unprocessed surfaces, the prepared superhydrophobic surfaces showed a significant increase in anti-icing performance. Finally, the mechanism of the delayed icing on the surface of the prepared ZnNi alloy superhydrophobic coating was analyzed. This research provided a feasible approach for the manufacturing of superhydrophobic anti-icing surfaces.

Numerical and experimental study on designs and performances of multi-serpentine flow field with bend-area block for proton exchange membrane fuel cell

The geometric modification of the flow field is an effective measure to improve the performance of proton exchange membrane fuel cell (PEMFC) and the mass transfer ability of reactants. In this paper, serpentine channels with geometric parameters containing various blocks to generate gas forced convection at the U-bends are established and numerically studied. Setting blocks at different angles at U-bends has different effects at the corners, offering a more flexible and variable region of active gas diffusion in the vertical direction. The area of high vertical velocity is increased by the Angle-Height combination design with low pressure drop and uniform temperature distribution. It is demonstrated that a vertical velocity of 0.4 m s−1 can be achieved around the block in the 135° series with half-height corner blocks, proving the existence of the mass transfer enhancement. Subsequently, experimental testing is conducted to verify the feasibility of the optimized flow field. The experimental results support the trend of block height influencing cell performance, with a maximum power density increase of 3.4 %. Modifying the U-bend corner structure has proven to be an effective technique for improving the overall performance of PEMFC, which can serve an important guidance for future flow field design.

Heat transfer assessment incorporated with entropy generation within a curved corner structure enclosing a cold domain

AbstractIn cold climates or winter countries, maintaining optimal room temperatures is essential for comfort and energy efficiency. Conventional square or rectangle‐shaped rooms often face challenges in achieving efficient heat transfer (HT) and uniform temperature distribution. To address these limitations, this study has been explored using curved corner cavities, varying their aspect ratio (AR = 1.0 and 0.5), and incorporating a circular shape cooler to enhance HT within the room. The curved corners promote better airflow circulation, creating a more efficient HT environment. The dimensionless governing equations and corresponding boundary conditions are solved numerically using the finite element method. This research aims to assess the optimized HT and entropy production within a curved corner cavity, varying their AR and enclosing a circular shape cooler to determine the most effective configuration for maximizing HT and energy efficiency in winter conditions. This study reveals that in the case without a cooler (WOC), the average Nusselt number () is higher in the curved rectangle cavity compared with the curved square cavity for all values. Using the curved square (AR = 1.0), increases by 191.86%, while with the curved rectangle (AR = 0.5), increases by 302.63% at . Additionally, in the case with a cooler (WC), is higher than the case WOC and , and an average total entropy increases for both the WOC and WC cases for all values. Transitioning from a square to a curved rectangle (AR = 0.5) WC, increases by 329.34% at . Furthermore, in the WOC case, the curved square cavity and, in the WC case, the curved rectangle show better energy efficiency and reduce environmental impact.

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.

Deep ultraviolet AlGaN-multiple quantum wells with photoluminescence enhanced by topological corner state

The AlGaN-based deep ultraviolet light-emitting diode (DUV LED) has advantages of environmentally friendly materials, tunable emission wavelength, and easy miniaturization. However, an increase in Al composition leads to a decline in the lattice quality, thereby reducing the internal quantum efficiency (IQE). In addition, the light extraction efficiency (LEE) is limited due to the strong transverse magnetization polarization emission from the multiple quantum wells. Here, we designed the topological corner structure in AlGaN-MQWs, and the high electric field intensity in a tiny space at the corner results in an extremely high local density of optical states (LDOS), which could shorten the luminescence decay time of the emitter and increase the radiative rate by 26 times. Meanwhile, because the excited topological corner state resonance mode is a transverse-electric mode, enhancing only the transverse-electric luminescence without any gain for transverse-magnetic luminescence, thereby significantly improving the light extraction efficiency. Finally, according to theoretical calculations, the IQE could reach 68.75% at room temperature.

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.

IntelliCage: the development and perspectives of a mouse- and user-friendly automated behavioral test system.

IntelliCage for mice is a rodent home-cage equipped with four corner structures harboring symmetrical double panels for operant conditioning at each of the two sides, either by reward (access to water) or by aversion (non-painful stimuli: air-puffs, LED lights). Corner visits, nose-pokes and actual licks at bottle-nipples are recorded individually using subcutaneously implanted transponders for RFID identification of up to 16 adult mice housed in the same home-cage. This allows for recording individual in-cage activity of mice and applying reward/punishment operant conditioning schemes in corners using workflows designed on a versatile graphic user interface. IntelliCage development had four roots: (i) dissatisfaction with standard approaches for analyzing mouse behavior, including standardization and reproducibility issues, (ii) response to handling and housing animal welfare issues, (iii) the increasing number of mouse models had produced a high work burden on classic manual behavioral phenotyping of single mice. and (iv), studies of transponder-chipped mice in outdoor settings revealed clear genetic behavioral differences in mouse models corresponding to those observed by classic testing in the laboratory. The latter observations were important for the development of home-cage testing in social groups, because they contradicted the traditional belief that animals must be tested under social isolation to prevent disturbance by other group members. The use of IntelliCages reduced indeed the amount of classic testing remarkably, while its flexibility was proved in a wide range of applications worldwide including transcontinental parallel testing. Essentially, two lines of testing emerged: sophisticated analysis of spontaneous behavior in the IntelliCage for screening of new genetic models, and hypothesis testing in many fields of behavioral neuroscience. Upcoming developments of the IntelliCage aim at improved stimulus presentation in the learning corners and videotracking of social interactions within the IntelliCage. Its main advantages are (i) that mice live in social context and are not stressfully handled for experiments, (ii) that studies are not restricted in time and can run in absence of humans, (iii) that it increases reproducibility of behavioral phenotyping worldwide, and (iv) that the industrial standardization of the cage permits retrospective data analysis with new statistical tools even after many years.

Enhanced dropwise condensation on downward-facing cross-shaped pillar-structured surfaces with mixed wettability

In this paper, a novel downward-facing cross-shaped pillar-structured surface with mixed wettability is conceived for enhancing dropwise condensation. A three-dimensional thermal lattice Boltzmann model is employed to investigate the condensation performance on the downward-facing cross-shaped pillar-structured surface with mixed wettability and the associated enhancement mechanism of dropwise condensation. The numerical investigation shows that the cross-shaped pillar-structured surface with mixed wettability exhibits much better condensation performance than the square pillar-structured surface with mixed wettability and the flat surface with mixed wettability due to the synergistic effects of structural effects and mixed wettability, which can promote the droplet nucleation and accelerate the condensate removal. Moreover, for different contact angles of the pillar top (θtop), there exists a competition between the droplet nucleation and the condensate removal on the downward-facing cross-shaped pillar-structured surface. It is found that, when θtop=60°, an optimal droplet dripping rate can be achieved due to a suitable balance between a relatively large mass of detached droplets and a short condensation cycle time. Furthermore, the aspect ratio (γ) has an important influence on the droplet dripping rate, i.e., as γ increases, the droplet dripping rate first exhibits small fluctuations, then increases rapidly before γ=1.0, and after that experiences a slight variation. The large droplet dripping rate achieved at γ=1.0 is mainly attributed to the fact that an optimum structure of the concave corner can promote the droplet nucleation, increase the length of the triple-phase contact line, advance the appearance of droplet coalescence, and finally accelerate the condensate removal.

Conormal homology of manifolds with corners

Given a manifold with corners X , we associate to it the corner structure simplicial complex \Sigma_X . Its reduced K-homology is isomorphic to the K-theory of the C^* -algebra \mathcal{K}_b(X) of b-compact operators on X . Moreover, the homology of \Sigma_X is isomorphic to the conormal homology of X . In this note, we construct for an arbitrary abstract finite simplicial complex \Sigma a manifold with corners X such that \Sigma_X\cong\Sigma . As a consequence, the homology and K-homology which occur for finite simplicial complexes also occur as conormal homology of manifolds with corners and as K-theory of their b-compact operators. In particular, these groups can contain torsion.

Radial and azimuthal seismic anisotropy in NW South America: Insights into crustal deformation and mantle flow using ambient noise and surface wave tomography

We illuminate the crustal and upper mantle structure of the northwestern corner of South America by mapping radial and azimuthal seismic anisotropy. Radial anisotropy is inferred from the discrepancy between VSV and VSH polarized S-velocities in horizontally propagating Rayleigh and Love waves, respectively. First, short-period (7–35 s) phase and group velocities are estimated from ambient noise cross-correlations, and long-period (40–170 s) group velocities are determined from fundamental-mode, surface-wave trains from earthquake sources at regional and teleseismic epicentral distances. Dispersion velocities are then tomographically inverted to develop maps of group velocity variation for periods between 7 and 170 s including azimuthal velocity dependence. We observe that positive anisotropy in the upper crust is related to thick Quaternary sequences in sedimentary basins, while negative anisotropy is found beneath active volcanoes and igneous-metamorphic terrains. Negative anisotropy features observed in the lower crust beneath the Eastern Cordillera suggest the existence of sill-like intrusions that penetrate the lower crust, thus supporting underplating mechanisms. Our study reveals SW-NE oriented fast axes of azimuthal anisotropy beneath the Eastern Cordillera, which strongly suggest the presence of shear zones within the fold and thrust belt system. Notably, the fast axes align parallel to the regional faults in the area, indicating a significant role in controlling faulting processes. Finally, we observe a wide trench-parallel zone of azimuthal anisotropy beneath the Nazca Plate, the Panama Block, and the Caribbean, which we associate with subslab mantle flow.

Corner Structure of Four-Dimensional General Relativity in the Coframe Formalism

AbstractThis note describes a local Poisson structure (up to homotopy) associated with corners in four-dimensional gravity in the coframe (Palatini–Cartan) formalism. This is achieved through the use of the BFV formalism. The corner structure contains in particular an Atiyah algebroid that couples the internal symmetries to diffeomorphisms. The relation with BF theory is also described.

A Novel Method for Building Contour Extraction Based on CSAR Images

Circular synthetic aperture radar (CSAR) can obtain more complete scattering characteristics by observing the target with different azimuth angles. Therefore, extracting the complete structure of the target from CSAR images is of great significance for accurate interpretation. At present, the artificial target extraction based on CSAR images mostly uses anisotropic scattering features. For special targets such as buildings, as the walls and the ground form dihedral corner structures, there are also obvious strong scattering features such as double-scattering lines in SAR images. Therefore, combining the strong scattering features of buildings at specific aspects with anisotropic scattering characteristics at different aspects can obtain better extraction results, and how to extract these features accurately and efficiently is the key point. Based on this, this paper proposes a novel method for building contour extraction based on CSAR images. For strong scattering features, a fast fuzzy C-means (FCM) clustering algorithm was used to extract them. For anisotropic scattering features, aspect entropy was used to characterize the anisotropy degree, and K-means clustering was combined to extract. Finally, a more accurate result is obtained by merging the two feature extraction results. In order to verify the effectiveness and practicability of the proposed method, a lot of measured data acquired by the self-developed airborne L-band and Ku-band CSAR systems were processed. The experiments show that, compared with state-of-the-art algorithms, the proposed method can obtain more accurate results in less time.

Process stability control of corner structures in robotic gas tungsten arc additive manufacturing via arc sensing

Aiming at a higher deposition rate, robotic gas tungsten arc additive manufacturing (GTA AM) always uses the front feed mode in which the wire is fed in front of the arc along the torch travel direction. However, fabricating corner structures in this mode is still a challenging issue in robotic GTA AM, since the serious hump height at corner points during torch rotation will hinder the process stability and automation of corner structures. The novelty of this study is to solve this issue by developing an in-situ monitoring and control strategy. An arc voltage sensor is designed to monitor the arc voltage that can characterize the deposition height. The arc voltage decreases first and then keeps stable at the corner points during torch rotation. It increases rapidly as the torch runs away from the corner points. An empirical mode decomposition (EMD) algorithm filters noises in sampled arc voltages. The peak arc voltage is selected to characterize the arc length since it presents fewer fluctuations than the base arc voltage. A Fuzzy-PID controller is developed for the peak arc voltage control by regulating the wire feed speed (WFS). Open-loop and closed-loop control tests of corner structures confirm that the deposition process with the fixed WFS is forced to terminate due to the serious hump height, and that with the controlled WFS can lower the hump height markedly at the corner points. This study demonstrates that the developed arc voltage sensing and control system can remove metal humps at the corner points and enhance the process automation of corner structures in robotic GTA AM.

Study on CO migration characteristics and hazard potential function under ventilation after roof cutting blasting

Multiple toxic gases, such as carbon monoxide (CO), are generated by roof-cutting blasting (RCB) in the automatically formed roadway without coal pillars (AFRCP). To eliminate potential hazards in time, a ventilation model was established based on field data from Dianping Coal Mine. The spatial and temporal evolution characteristics of CO under different conditions after roof-cutting by shaped-charge blasting (SCB) and shaped-charge hydraulic blasting (SCHB), respectively, were investigated by using the Computational Fluid Dynamics (CFD) method. The results demonstrate that the CO gas cloud presents the coupling effect of movement and dilution under ventilation. The charge mainly affects the peak value of CO concentration (PVC). The air velocity affects the PVC and the CO gas cloud's over-limit time (OLT) and migration velocity. Roadway cross-sectional area and corner structure affect the PVC by influencing local air velocity. The CO hazard potential functions of the roadway after RCB were established, indicating a Gaussian-like distribution. The maximum hazard potential of SCHB was found to be 60% lower than that of SCB, and the re-entry time for personnel reduced by 36%. This study can serve as a guide for optimizing the ventilation design of roadways after RCB and contribute to the promotion of AFRCP.

Study on seismic behaviors of steel–concrete composite shear walls with novel corner designs

Steel–concrete composite shear walls are common structures that resist lateral forces and are typically damaged at the corners under seismic loading. In this study, novel corner designs of steel–concrete composite shear walls were proposed based on the design concept of plastic damage relocation. The seismic behavior of the designed corner structures of the steel–concrete composite shear wall was investigated using a low-cyclic lateral loading test. The failure mode, hysteretic curve, crack development, energy dissipation capacity, and stiffness degradation were analyzed based on the experimental results. To optimize the proposed corner designs, a finite element model was developed and validated experimentally, and a parametric study was conducted to determine the effects of the length–width ratio (α) and thickness ratio (β) of the stiffer to the steel plate and thickness ratio (λ) of the corner section steel to the steel plate on the seismic behaviors of the proposed composite shear wall. The experimental results showed that the seismic performance of the proposed steel–concrete composite shear wall was much better than that of a conventional shear wall. The results of the parametric study suggest that β and λ have little effect, and α should be 0.2 to achieve optimal seismic performance. This study provides a basic measurement to improve the seismic performance of steel–concrete composite shear walls, and promotes their development and application.

Polymer valley photonic crystals with honeycomb structures for terahertz waveguides

Terahertz (THz) band has promising applications in next-generation wireless communications and new sensing technologies. However, the on-chip transmission of THz waves will encounter strong scattering at sharp corner structures of waveguides. Recently, valley photonic crystals (VPC) offer new possibilities for high-fidelity transmission of THz wave along complex shape waveguides. The VPC-based waveguide overcomes defects and sharp corners, probably resulting in high-performance on-a-chip THz devices. The THz VPC with polymer materials can be easy and low-cost building with 3D printing technology. In this paper, the VPC waveguides operating around 300 GHz are constructed using honeycomb lattices on a thin polymer plate. The mirror symmetry is broken by proper air-circular apertures located in the honeycomb lattice with a nontrivial band structure. Then the influences on the band structure by the polymer refractive index ranging from 1.5∼2.0, the thickness of the sheet, and the asymmetry of aperture diameters in the lattice are discussed. The transmission of straight, zigzag, and “omega” waveguides made of the polymer VPCs is simulated. The results demonstrate their high transmission efficiency and robustness to scattering from sharp bending above −10 dB with an 8-GHz bandgap. The proposed polymer VPC structure paves way for THz applications such as efficient beam splitters, low-loss complex-shaped waveguides, and robust delay lines.

Investigation on the heat dissipation of high heat flux chip array by fractal microchannel networks

With the development of integrated circuits, high power, and high integration chip array devices are facing the requirements of high heat flux and temperature uniformity. The micro-channel heat sink can meet the heat dissipation requirements of chip array devices with high heat flux, and the flow channel with fractal structure can achieve high temperature uniformity of chip array. In this study, the H-shaped fractal micro-channel structure was proposed to cooling the 4?4 chip (1 ? 1 mm) array. The interior fillet structure was introduced to optimize T-shaped and L-shaped corner structures in the fractal channel. The simulation results show that the overall pressure drop of micro-channel heat sink with is reduced 18.7%, and the maximum temperature difference of 4?4 chip array is less than 1.2? at 1000 W/cm2. The micro-channel heat sink with interior fillet structure interior fillet structure was fabricated and assembled, and the hydro-thermal performance was characterized by thermal test chip at different flow rates and heat fluxes. The experimental results show that the standard deviation of temperature of 4?4 chip array is less than 3.5? at 1000 W/cm2 and 480 ml per minute. The error between experimental and simulation data is within ?1.5%, which proves the reasonability of CFD modelling and simulation. Furthermore, the results demonstrate that by introducing interior fillet structure into the T-shaped and L-shaped structures could reduce pumping power and improve temperature uniformity of chip array, which can be applied to improve the performance of the chip array devices with high heat flux.