Concave Geometry Research Articles

ZygoPlanner: A three-stage graphics-based framework for optimal preoperative planning of zygomatic implant placement

Zygomatic implant surgery is an essential treatment option of oral rehabilitation for patients with severe maxillary defect, and preoperative planning is an important approach to enhance the surgical outcomes. However, the current planning still heavily relies on manual interventions, which is labor-intensive, experience-dependent, and poorly reproducible. Therefore, we propose ZygoPlanner, a pioneering efficient preoperative planning framework for zygomatic implantation, which may be the first solution that seamlessly involves the positioning zygomatic bones, the generation of alternative paths, and the computation of optimal implantation paths. To efficiently achieve robust planning, we developed a graphics-based interpretable method for zygomatic bone positioning leveraging the shape prior knowledge. Meanwhile, a surface-faithful point cloud filling algorithm that works for concave geometries was proposed to populate dense points within the zygomatic bones, facilitating generation of alternative paths. Finally, we innovatively realized a graphical representation of the medical bone-to-implant contact to obtain the optimal results under multiple constraints. Clinical experiments confirmed the superiority of our framework across different scenarios. The source code is available at https://github.com/Haitao-Lee/auto_zygomatic_implantation.

An integrated approach of support vector machine (SVM) and weight of evidence (WOE) techniques to map groundwater potential and assess water quality

This study addresses the critical need for effective groundwater (GW) management in Muzaffarabad, Pakistan, amidst challenges posed by rapid urbanization and population growth. By integrating Support Vector Machine (SVM) and Weight of Evidence (WOE) techniques, this study aimed to delineate GW potential zones and assess water quality. This study fills the gap in applying advanced machine learning and geostatistical methods for accurate GW potential mapping. Eight thematic layers based on topography, hydrology, geology, and ecology were utilized to compute the GW potential model. Additionally, water quality analysis was performed on collected samples. The findings indicate that flat and gently sloping terrains, areas with an elevation range of 611 –687 m, and concave slope geometries are associated with higher GW potential. Additionally, proximity to drainage and high-density lineament zones contribute to increased GW potential. The results showed that 31.1% of the area had excellent GW potential according to the WOE model, whereas the SVM model indicated that only 20.3% fell in the excellent potential zone. Results showed that both models performed well in the delineating GW potential zones. Nevertheless, the application of the SVM method is highly recommended which will be benefited in GW resources management related to urban planning. The study also evaluates the spatial distribution of GW quality, with a focus on physical and chemical parameters, including electrical conductivity, pH, turbidity, total dissolved solids, calcium, magnesium, chloride, nitrate, and sulphate. Bacterial contamination assessment reveals that 76% of spring water samples (30 out of 39 samples) are contaminated with E.coli, raising public health concerns. Based on the chemical analysis of GW samples the study identified exceedances of WHO guidelines for calcium in two samples, magnesium in seven samples, sulphate in ten samples, and nitrate levels were below the WHO guideline across all samples. These results highlight localized chemical contamination issues that require targeted remediation efforts to safeguard water quality for public health.

Selectively Extending the Curved Side of N-Doped Hexa-peri- hexabenzocoronene.

A curved nanographene, conceptually by insertion of nitrogen into a trapezoidal planar nanographene at the edge was synthesized by π-extension of the nitrogen-doped hexa-peri-hexabenzocoronene. This N-doped nanographene exhibited a π-electronic concave face containing a nonaromatic azepine ring in the middle with a size of 14.0 Å length and 4.0 Å depth, which represents an unprecedented half-side concave geometry of curved nanographene. The bent π-extension exhibited a low degree of conjugation suggested by calculation results. Due to the unique 3D structure and electron-rich property, this nanographene showed pronounced intermolecular charge transfer with C60.

A Review of the Homogenized Lattice Boltzmann Method for Particulate Flow Simulations: From Fundamentals to Applications

The homogenized lattice Boltzmann method (HLBM) has emerged as a flexible computational framework for studying particulate flows, providing a monolithic approach to modeling pure fluid flows and flows through porous media, including moving solid and porous particles, within a unified framework. This paper presents a thorough review of HLBM, elucidating its underlying principles and highlighting its diverse applications to particle-laden flows in various fields as reported in literature. These include studies leading to new fundamental knowledge on the settling of single arbitrarily shaped particles as well as application-oriented research on wall-flow filters, hindered settling, and evaluation of the damage potential during particle transport. Among the strengths of HLBM are its monolithic approach, which allows seamless simulation of different fluid-solid interactions, and its ability to handle arbitrary particle shapes, including irregular and concave geometries, while resolving surface interactions to capture local forces. In addition, its parallel scheme based on the lattice Boltzmann method (LBM) results in high computational efficiency, making it suitable for large-scale simulations, even though LBM requires small time steps. Important future development needs are identified, including the addition of a lubrication force correction model, performance enhancements, such as support for hybrid parallelization and GPU, and the extension of compatible contact models to accommodate concave shapes. These advances promise expanded capabilities for HLBM and broader applicability for solving complex real-world problems.

Novel additive-manufactured tracking solar concentrating system for cooking applications: Design, geometry assessment, and optical evaluation

A novel solar concentrating system for cooking applications was developed, featuring a stationary reflector and a flat heliostat with equatorial tracking. This design allows for simple one-axis tracking at a constant speed with no need for deformable reflectors, ensuring the direction of the concentrated radiation in the cooking area remains steady and a quasi-constant power capture regardless of the Sun's position. The concentrator is made from 3D printed flat tiles, allowing for an easy do-it-yourself manufacturing process and avoiding highly focused irradiance on the receiver. The geometry of the reflector was scanned and compared to an ideal CAD reflector model, revealing some assembly imperfections, and a slightly concave tile geometry which causes a moderately sharp concentration peak. The irradiance distribution on a plane target near the effective focus of the reflector was analysed with a photographic flux mapping technique, and the results were compared to those obtained from ray tracing simulations of the ideal CAD model, confirming the tile concavity predicted by the geometrical examination. Conversely, it shows a reduction in the total energy gathered on the entire target plate when compared with ray tracing outcomes.

Preliminary experimental investigation on hemming of curved edge parts by means of incremental sheet forming

In the context of versatile and environmentally friendly joining techniques, joining by forming has proven to be a very useful tool. From this category, hemming is widely used for sheet metal parts like car body panels. Still, hemming of concave and convex geometries represents a challenge for conventional hemming as well as for the more flexible roller hemming. Especially for smaller radii and greater flange lengths, these methods can reach their limits. In the present work, incremental sheet forming (ISF), a flexible forming process without dedicated tools and high formability, is utilized to implement the hemming process. Due to its local and incremental deformation characteristics, a favorable material flow in the flange area is expected, which might prevent cracking and wrinkling. Therefore, the material flow in ISF-hemming will be investigated. Closed circular specimens with radii of 50 mm and 200 mm and varying flange lengths are analyzed. Conclusions about the material flow are drawn by measuring the change in sheet thickness and elongation of the flange. The results show that, for stretch hemming, considerable thinning and elongation of the flange takes place and no cracking is detected. For shrink hemming, significant thickening of the flange and elongation in radial direction is observed, which suppresses wrinkling.

Numerical study of solar evaporation in 3D-printed structures

In this study, we used three-dimensional (3D) printed concave geometries filled with activated carbon to create a unique 3D solar evaporator for clean water production. The evaporation process was modeled considering airflow and solar radiation to investigate the advantages of 3D concave geometries. This work encompasses a series of studies, focusing on mass transfer inside the concavity and around the structure, to elucidate specific exchange points. Additionally, the research explores the effects of air velocity and the incorporation of additional holes within the structure, with the aim of improving evaporation.

Cu2+-Dominated Chirality Transfer from Chiral Molecules to Concave Chiral Au Nanoparticles.

Foreign ions as additives are of great significance for realizing excellent control over the morphology of noble metal nanostructures in the state-of-the-art seed-mediated growth method; however, they remain largely unexplored in chiral synthesis. Here, we report on a Cu2+-dominated chiral growth strategy that can direct the growth of concave chiral Au nanoparticles with C3-dominant chiral centers. The introduction of trace amounts of Cu2+ ions in the seed-mediated chiral growth process is found to dominate the chirality transfer from chiral molecules to chiral nanoparticles, leading to the formation of chiral nanoparticles with a concave VC geometry. Both experimental and theoretical results further demonstrate the correlation between the nanoparticle structure and optical chirality for the concave chiral nanoparticle. The Cu2+ ion is found to dominate the chiral growth by selectively activating the deposition of Au atoms along the [110] and [111] directions, facilitating the formation of the concave VC. We further demonstrate that the Cu2+-dominated chiral growth strategy can be employed to generate a variety of concave chiral nanoparticles with enriched geometric chirality and desired chiroptical properties. Concave chiral nanoparticles also exhibit appealing catalytic activity and selectivity toward electrocatalytic oxidation of enantiomers in comparison to helicoidal nanoparticles. The ability to tune the geometric chirality in a controlled manner by simply manipulating the Cu2+ ions as additives opens up a promising strategy for creating chiral nanomaterials with increasing architectural diversity for chirality-dependent optical and catalytic applications.

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.

Overriding Plate Thickness as a Controlling Factor for Trench Retreat Rates in Narrow Subduction Zones

AbstractSlab width is a significant factor in controlling subduction zone dynamics, particularly the retreat velocities, which tend to decrease with wider slabs. However, observations of natural narrow subduction zones reveal no correlation between slab width and trench velocities. This suggests that other factors may exert a greater influence. In this study, we employ 3D numerical subduction models to systematically assess the impact of slab width, strength of slab coupling to the lateral plate (LP), and overriding plate (OP) thickness on trench kinematics and geometry. Our models focus on narrow slabs (400–1,200 km), and the results demonstrate that, in the case of narrow subduction zones, the slab width has little effect on trench migration rates and the viscous coupling at the lateral slab edge is only important for very narrow subduction zones (≤800 km). Conversely, the OP thickness emerges as a crucial factor, with increasing plate thickness leading to a strong decrease in trench velocities. These findings provide an explanation for the observed trench velocities in natural narrow subduction zones, where an inverse relationship with OP thickness is evident. Furthermore, our study reveals that not only slab width, but also the OP thickness and the slab coupling to the LP, significantly influence trench geometry. Strong lateral coupling promotes the formation of concave trench geometries, while thick overriding plates favor the development of “w”‐shaped geometries. Overall, a comprehensive understanding of subduction processes necessitates considering the interplay between slab width, OP thickness, and slab coupling to the LP.

Long‐cycling Zinc Metal Anodes Enabled by an In Situ Constructed ZnO Coating Layer

AbstractSuppressing dendrite growth in zinc (Zn) anodes for aqueous Zn batteries remains a significant challenge. Modifying the Zn/electrolyte interface stands out as one of the most promising strategies to tackle this problem. In this study, a nanometer‐thick ZnO coating layer with a uniform concave surface geometry is in situ constructed to modify the Zn anode for the first time. The chemical bond formed between the ZnO layer and the Zn foil enhances the structural stability of the synthesized ZnO modified‐Zn anode. Finite element simulations indicate that the ZnO coating layer facilitates uniform electric field distribution and zinc flux on the Zn electrode. In situ optical observations unveil how the modification interface regulates zinc plating behaviors on the Zn anode. Impressively, the symmetrical ZnO‐Zn cell displays a remarkable cycling stability of 1765 h at a current density of 5 mA cm−2 with an areal capacity of 1 mAh cm−2. Even when subjected to a very high current density of 50 mA cm−2, it maintains stable operation over 3800 cycles. This success highlights the immense application potential of the rationally tailored ZnO‐Zn anode.

An Euler–Bernoulli-type beam model of the vocal folds for describing curved and incomplete glottal closure patterns

Incomplete glottal closure is a laryngeal configuration wherein the glottis is not fully obstructed prior to phonation. It has been linked to inefficient voice production and voice disorders. Various incomplete glottal closure patterns can arise and the mechanisms driving them are not well understood. In this work, we introduce an Euler–Bernoulli composite beam vocal fold (VF) model that produces qualitatively similar incomplete glottal closure patterns as those observed in experimental and high-fidelity numerical studies, thus offering insights into the potential underlying physical mechanisms. Refined physiological insights are pursued by incorporating the beam model into a VF posturing model that embeds the five intrinsic laryngeal muscles. Analysis of the combined model shows that co-activating the lateral cricoarytenoid (LCA) and interarytenoid (IA) muscles without activating the thyroarytenoid (TA) muscle results in a bowed (convex) VF geometry with closure at the posterior margin only; this is primarily attributed to the reactive moments at the anterior VF margin. This bowed pattern can also arise during VF compression (due to extrinsic laryngeal muscle activation for example), wherein the internal moment induced passively by the TA muscle tissue is the predominant mechanism. On the other hand, activating the TA muscle without incorporating other adductory muscles results in anterior and mid-membranous glottal closure, a concave VF geometry, and a posterior glottal opening driven by internal moments induced by TA muscle activation. In the case of initial full glottal closure, the posterior cricoarytenoid (PCA) muscle activation cancels the adductory effects of the LCA and IA muscles, resulting in a concave VF geometry and posterior glottal opening. Furthermore, certain maneuvers involving co-activation of all adductory muscles result in an hourglass glottal shape due to a reactive moment at the anterior VF margin and moderate internal moment induced by TA muscle activation. These findings have implications regarding potential laryngeal maneuvers in patients with voice disorders involving imbalances or excessive tension in the laryngeal muscles such as muscle tension dysphonia.

The dynamic analysis of axisymmetric bodies with damping effects using the modified radial integration boundary elements method (MRIBEM)

This paper investigates the elastodynamic analysis of axisymmetric bodies under axisymmetric dynamic loads using the modified radial integration boundary elements method (MRIBEM). Purposely, the governing integral equations have been developed in cylindrical coordinates by employing the three-dimensional (3D) static fundamental solution. The axisymmetric bodies can be modeled as a two-dimensional (2D) problem, which is much simpler than 3D analysis and only requires a one-dimensional boundary mesh. In the proposed formulation, the effects of inertial and damping forces appear as 2D domain integrals. The domain variables are approximated using global radial basis functions (RBFs), and the modified radial integration method (MRIM) is employed to deal with the domain integral as the main idea of the present research. Various sample problems are provided in order to illustrate the capability of the presented method for analyzing axisymmetric bodies with concave geometry and damping effect under different types of transient loads. The Newmark and Houbolt methods were applied for time marching, and their efficiency was examined. The results of the present study were also validated by the axisymmetric FEM formulation and other available references.

Reliable non-destructive detection and characterization of material degradation caused by high-temperature corrosion

Components made from nickel-based superalloys are widely used in gas turbines for aircraft and power plants. In addition to high corrosion resistance, they feature very good creep and fatigue strength at temperatures near 1000 °C. Yet, corrosive attack can significantly reduce the mechanical properties, and thus the expected remaining service life of these components. Therefore, in the case of safety-critical parts, detailed information on the component’s actual condition is crucial. In the present study, a non-destructive electromagnetic testing technique was developed that is capable of reliably detecting early degradation caused by high-temperature corrosion on components made of nickel-based alloys. The testing technique combines the use of temperature-resistant sensors and a variation of the component temperature in a wide range. This allows the determination of the magnetic properties of the component as a function of temperature. It was shown that the measurement signals obtained correlates with the degree of chromium depletion. Thus, a reliable and non-destructive detection of degradation caused by high-temperature corrosion was possible. A special feature of the presented testing technique is that degradation can be detected at an earlier stage compared to conventional methods. In addition, the technique enables the characterization of the microstructure condition directly in the component. The applicability of the testing technique was demonstrated for components with concave surface geometries, like turbine blades.

Virial coefficients of hard, homonuclear dumbbells in two- to four-dimensional Euclidean spaces.

We calculated virial coefficients up to the eighth order for hard dumbbells in two-, three-, and four-dimensional Euclidean spaces employing Mayer-sampling Monte Carlo simulations. We improved and extended available data in two dimensions, provide virial coefficients in R^{4} in dependence on their aspect ratio, and recalculated virial coefficients for three-dimensional dumbbells. Highly accurate, semianalytical values for the second virial coefficient of homonuclear, four-dimensional dumbbells are provided. We compare the influence of the aspect ratio and the dimensionality to the virial series for this concave geometry. Lower-order reduced virial coefficients B[over ̃]_{i}=B_{i}/B_{2}^{i-1} depend in first approximation linearly from the inverse excess part of their mutual excluded volume.

Shape-Mediated Oriented Assembly of Concave Nanoparticles under Cylindrical Confinement.

This contribution describes the self-assembly of colloidal nanodumbbells (NDs) with tunable shapes within cylindrical channels. We present that the intrinsic concave geometry of NDs endows them with peculiar packing and interlocking behaviors, which, in conjunction with the adjustable confinement constraint, leads to a variety of superstructures such as tilted-ladder chains and crossed-chain superlattices. A mechanistic investigation, corroborated by geometric calculations, reveals that the phase behavior of NDs under strong confinement can be rationalized by the entropy-driven maximization of the packing efficiency. Based on the experimental results, an empirical phase diagram is generated, which could provide general guidance in the design of intended superstructures from NDs. This study provides essential insight into how the interplay between the particle shape and confinement conditions can be exploited to direct the orientationally ordered assembly of concave nanoparticles into unusual superlattices.

Towards the limitation of optical absorption dissipations of amorphous silicon solar cells based on annular concave anti-reflecting coating

We present in this research study an investigation towards the limitation of absorption reduction through Si solar cells with the variation of the angle of incidence. Our study is essentially based on the design of an anti-reflecting coating from a single period of one-dimensional quadrant photonic crystals (PCs) with concave and convex curvatures. Moreover, the effect of the one-dimensional PCs as a back mirror on the absorption of the cell was investigated. The numerical findings show that the solar cell absorption is significantly affected by the change in the angle of incidence. For concave an anti-reflecting coating, as the radius of curvature decreases to 50 nm, the solar cell absorption investigates significant enhancements with the angle of incidence. Considering planar and concave geometries is more preferred than the convex one whatever the radius of curvature of the constituent layers. The presence of an anti-reflecting coating with a small value of the radius of curvature is the most compatible design for silicon solar cells for capturing most of the incident photons on the cell and improving the cell absorption as well.

Double-atom dealloying-derived Frank partial dislocations in cobalt nanocatalysts boost metal–air batteries and fuel cells

Oxygen reduction reaction (ORR), an essential reaction in metal-air batteries and fuel cells, still faces many challenges, such as exploiting cost-effective nonprecious metal electrocatalysts and identifying their surface catalytic sites. Here we introduce bulk defects, Frank partial dislocations (FPDs), into metallic cobalt to construct a highly active and stable catalyst and demonstrate an atomic-level insight into its surface terminal catalysis. Through thermally dealloying bimetallic carbide (Co3ZnC), FPDs were in situ generated in the final dealloyed metallic cobalt. Both theoretical calculations and atomic characterizations uncovered that FPD-driven surface terminations create a distinctive type of surface catalytic site that combines concave geometry and compressive strain, and this two-in-one site intensively weakens oxygen binding. When being evaluated for the ORR, the catalyst exhibits onset and half-wave potentials of 1.02 and 0.90 V (versus the reversible hydrogen electrode), respectively, and negligible activity decay after 30,000 cycles. Furthermore, zinc-air batteries and H2-O2/air fuel cells built with this catalyst also achieve remarkable performance, making it a promising alternative to state-of-the-art Pt-based catalysts. Our findings pave the way for the use of bulk defects to upgrade the catalytic properties of nonprecious electrocatalysts.

Assessment of the Susceptibility to Material Fracture in the Cross-Wedge Rolling Process with Concave Tools.

The internal cracking of forgings during the cross-wedge rolling (CWR) process is a serious limitation that prevents the correct implementation of this process. The phenomenon of material cracking in the CWR process reduces the technological and application possibilities of this highly efficient process, which can produce forgings with high geometric accuracy. This article presents the results of rolling forgings at different temperatures. An analysis of the results showed that the size of the resulting material fracture in the CWR process is related to the size of the ovalisation of the cross-section of the forging formed during rolling. On the basis of the observations made, it was proposed to realise the cross-wedge rolling process with concave tools. The use of tools with a concave geometry is intended to reduce the excessive flow of material in the rolling direction, which restrains the formation of the ovalisation of the cross-section of the forging. Numerical simulations were carried out comparing the rolling with flat tools and concave tools with different radii of the curvature. The results show that the use of concave tools reduces the ovality of the cross-section of the forging during rolling and reduces the value of the normalised Cockcroft–Latham (CL) fracture criterion.

Ultraflexible and Ultrasensitive Near‐Infrared Organic Phototransistors for Hemispherical Biomimetic Eyes

AbstractThe diverse biological eyes vision systems found in nature can provide attractive design inspiration for near‐infrared (NIR) imaging devices. Outstanding features of the retina are its concave hemisphere geometry and high‐sensitivity image acquisition, which simplify the optical complexity of the eye and improve the imaging quality of visual perception. However, developing high‐performance NIR biomimetic imaging systems with these characteristics is extremely challenging due to the limitations of their hemisphere‐like structures, constituent materials, and conventional imaging modules. Here, a hemispherical biomimetic eyes imaging system based on ultraflexible all‐polymer heterojunction NIR phototransistors is presented. The device features a self‐supporting ultrathin (≈659 nm) NIR imaging structure that can maintain stable photoelectric performance while adhering to the human body or arbitrary‐shaped objects and have extraordinary photosensitivity (≈106) under dim light conditions (0.038 mW cm−2, 808 nm). Based on the versatile NIR device array, hemispherical ultrasensitive NIR biomimetic eyes are successfully achieved and higher‐resolution imaging is realized. Results demonstrated in this work provide a new strategy for constructing ultraflexible and ultrasensitive NIR photodetectors, showing remarkable application potential in next‐generation visual prosthetics and intelligent bioimaging systems.