Triangular Surface Research Articles

Magnetic Breakdown and Topology in the Kagome Superconductor CsV_{3}Sb_{5} under High Magnetic Field.

The recently discovered layered kagome metals of composition AV_{3}Sb_{5} (A=K, Rb, Cs) exhibit a complex interplay among superconductivity, charge density wave order, topologically nontrivial electronic band structure and geometrical frustration. Here, we probe the electronic band structure underlying these exotic correlated electronic states in CsV_{3}Sb_{5} with quantum oscillation measurements in pulsed fields up to 86T. The high-field data reveal a sequence of magnetic breakdown orbits that allows the construction of a model for the folded Fermi surface of CsV_{3}Sb_{5}. The dominant features are large triangular Fermi surface sheets that cover almost half the folded Brillouin zone. These sheets have not yet been detected in angle resolved photoemission spectroscopy and display pronounced nesting. The Berry phases of the electron orbits have been deduced from Landau level fan diagrams near the quantum limit without the need for extrapolations, thereby unambiguously establishing the nontrivial topological character of several electron bands in this kagome lattice superconductor.

Modelling large-scale landslide using a GPU-accelerated 3D MPM with an efficient terrain contact algorithm

The material point method (MPM) simulation of large-scale landslides can provide useful information to response to landslide hazards in mountainous regions. However, the structured background meshes commonly adopted in MPM fail to accurately capture the complex terrain above which the sliding mass moves. In this work, a novel terrain contact algorithm is proposed and integrated into a GPU-accelerated 3D MPM to model large-scale landslides. The complex terrain is modelled by a fixed triangular surface mesh generated according to the digital elevation model (DEM) and the interaction between the sliding mass and the basal surface is modelled by a contact algorithm between the triangular surface mesh and the material points. Furthermore, a contact detection algorithm based on level-set functions is developed to improve the contact detection efficiency. The detailed computational formulations and numerical implementation based on GPU parallel computing are presented. After the correctness and the efficiency being verified by two numerical examples, the proposed method is applied to simulate the catastrophic Baige landslide that occurred in China in 2018. The results indicate that the present method is both accurate and efficient and can provide a useful tool for numerical study on landslides.

Experimental assessment and modeling of solar air heater with V shape roughness on absorber plate

A roughness of the absorber plate can improve the efficiency of a solar air heater. To boost the efficiency of triangle solar air heaters, this research presents the results of a comparison study between with and without rib roughness on absorber plates. Both use black paint with graphene nanoparticles infused into it, coating an absorber plate. Both numerical and experimental methods have been used to examine the impact of surface roughness on friction factors and heat transport properties. ANSYS 14.5 software module and RNG turbulence, k-€ model is used to conduct a three-dimensional simulation and solve the governing equations in the turbulent situation. Based on experimental data, it has been established that smooth plates are more efficient in converting heat into useful work than rough ones, on average, by a factor of 4.82 and 4.46, respectively. The length of the duct in the solar air heater mitigates the temperature gradient seen in the simulation result. The roughness of V-shaped ribs has a far larger effect on the heat transfer and friction factor properties than do variations in relative roughness pitch (P/e) and Reynolds number (Re). Experimental observations supported by modeling and simulation confirms that triangular duct absorber surface roughness provides improved outcome.

Modeling of magnetic cilia carpet robots using discrete differential geometry formulation

Cilia broadly exist in a wide range of living systems. The metachronal waves generated by arrays of beating cilia are essential for realizing complex biological functions, such as locomotion and transportation, which have inspired the design in advanced engineering systems, e.g., programmable cilia-inspired soft robots. However, due to lack of efficient dynamic modeling and numerical explorations on such complex active systems, design and control of cilia-inspired soft robots usually involve empirical approaches or highly time-consuming numerical simulations. Here, we report a numerical framework based on the discrete differential geometry (DDG) for the dynamic analysis of bio-inspired cilia carpet robots powered by external magnetic field. The active cilia is modeled as discrete magneto-elastic rods (DMER) and the carpet by discrete elastic plate (DEP) method, which are geometrically rigorous frameworks for the nonlinear mechanics of flexible structures. The clamped-type connection between slender cilia and thin carpet is achieved by introducing a special coupling element between rod segments and triangular carpet surfaces. The intersection-free contact and frictional interaction between soft robots and rigid ground is captured based on incremental potential energy theory and lagged dissipative principle, respectively, and, therefore, the constrained elastodynamic system equations can be solved implicitly through a variational approach. Two types of typical dynamic locomotion – crawling and rolling – are considered to demonstrate the effectiveness and robustness of our numerical method. The results show that the locomotion efficiency of the robot depends on the structural design. We also demonstrate that the crawling pathways (e.g., turning) can be programmed via selective actuation. This computationally efficient dynamic framework can not only provide insights on fundamental understanding of the biophysics of microorganisms, but also provide guidelines on the optimal design of cilia-inspired soft robots for biomedical applications.

Lateral malleolar crest and its clinical importance.

During study of anatomy of a fractured posterior malleolus of the ankle on CT scans, the authors noticed a prominent crest on the lateral malleolus, which they termed the lateral malleolar crest (LMC). As, in their view, LMC is a clinically important structure which was only briefly mentioned by a few authors without an official term, they focused on the anatomy of this structure. A total of 352 dry fibulae were analyzed and the following parameters recorded: (F) length of the fibula, (LMC) total length of LMC, (A) length of the part of the examined crest from the superior border of the articular facet of the lateral malleolus (AFLM) to its most proximal intersection with the midline of the fibula, (B) height of the medial triangular rough surface, and (A/F) A/F ratio. The crest was observed in all specimens. (F) was 346.5 ± 26mm (95% confidence interval [CI] 344-349), (LMC) was 85.4 ± 11.6mm (95% CI 84.2-86.6), (A/F) was 25% ± 3% (95% CI 24.7-25.3) in the whole group. (A) was 25.9 ± 6.5mm (95% CI 24.8-26.8) in the whole group, (B) was 34.9 ± 4.7mm (95% CI 34.3-35.5) in the whole group, 36 ± 6.1mm (95% CI 35.1-36.9). LMC is an important structure on the lateral malleolus. The knowledge of its anatomy is essential for placement of syndesmotic screws or/and the fibular plate.

Divergence factor correction of shooting and bouncing ray method for triangular meshed curved targets

In this letter, the divergence factor (DF) correction is implemented in the shooting and bouncing ray method (SBR) to improve the accuracy of radar cross section (RCS) simulations of triangular meshed curved targets. Based on the surface fitting technique and differential geometry, the curvature information of the triangular surface mesh is reconstructed and the resulting DF of the wavefront is taken into account. For the diverging ray tube, a supersampling ray tracing method is proposed to address the ray-mesh resolution mismatch. This enables us to accurately find the illuminated region on the target surface. Meanwhile, the divergence coefficient is introduced to correct the incident field. The monostatic RCSs of some targets with curved structures are simulated. The simulation results validate the effectiveness of DF correction for SBR in improving the accuracy of RCS simulations of curved targets.

Silicone Wristband Spray Ionization Mass Spectrometry for Combined Exposome and Metabolome Profiling

AbstractWearing a silicone wristband exposes the internal surface of the wristband to glucose, lipids, and metabolites (metabolome) found in sweat and the external surface to occupational and environmental factors that could impact health found in the air (exposome). We use silicone wristband electrospray ionization mass spectrometry (SWESI‐MS) to monitor these species. A 20‐μL drop of a (1 : 1, v/v) water:methanol solution is sufficient to extract abundant metabolites and contacting chemicals derived from ingestion of drink, smoke, diet, drug, and air pollution exposure. A wide coverage of species is successfully detected and identified from a worn wristband including caffeine, glucose, nicotine, reserpine, lactate, phosphocreatinine, oleic acid, and urea. The signal from a triangular wristband surface triggered by applying a voltage of 5 kV to form a spray remains stable for at least 2 minutes. The response is linear from 10 pM to 100 μM. The SWESI‐MS method offers the advantages of onsite sampling, no preprocessing, simple testing, and automatic high‐dimensional data searching. It can be used for simultaneously monitoring hazardous chemical contamination and abnormal expression of sweat‐secreted metabolites that are indicative of some physiological condition.

Giant electron-phonon interaction for a prototypical semiconductor interface: Sn/Ge(111)−(3×3)

We report an experimental and theoretical study of the electron-phonon coupling for $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Sn}/\mathrm{Ge}(111)$, a prototypical triangular lattice surface, closely related to $\mathrm{Sn}/\mathrm{Si}(111)\text{\ensuremath{-}}(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})$, where recent experimental evidence has found superconductivity [X. Wu et al., Phys. Rev. Lett. 125, 117001 (2020)]. We concentrate our study on the ($3\ifmmode\times\else\texttimes\fi{}3$) phase of $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Sn}/\mathrm{Ge}(111)$ that appears between 150 and 120 K and has a well-known geometry with a half-filled electronic band around the Fermi energy. We show that this surface presents a giant electron-phonon interaction that can be considered at least partially responsible for the different phases that this system shows at very low temperature. Our theoretical results indicate that indeed the electron-phonon interaction in $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Sn}/\mathrm{Ge}(111)\text{\ensuremath{-}}(3\ifmmode\times\else\texttimes\fi{}3)$ is unusually large, since we find that $\ensuremath{\lambda}$, the electron mass enhancement for the half-filled band, is $\ensuremath{\lambda}=1.3$. This result is in good agreement with the experimental value obtained from high-resolution angle-resolved photoemission spectroscopy measurements, which yield $\ensuremath{\lambda}=1.45\ifmmode\pm\else\textpm\fi{}0.1$.

Energy buffer mechanism for heat transfer enhancement in grooved channel cooling with flow intermittency

Driven by the ever-growing heat load in industrial applications such as fast charging electrical vehicle batteries and high-performance processors, advanced cooling technologies for efficient thermal management are urgently needed. This numerical work demonstrates the great potential of flow intermittency in grooved channels for thermal performance improvement at laminar condition, and aims to reveal the underlying mechanism that governs the heat transfer enhancement. The open-source computational fluid dynamics code OpenFOAM is employed to resolve the intermittent channel flow with triangular surface grooves. The time-averaged Reynolds number Re m = 100 and the Strouhal number St = 0.2 are maintained, while the close time ratio γ ranges from 0.1 to 0.9. The thermal performance improvement is attributed to the “energy buffer” mechanism by cavity vortices, which induces strong near-wall reverse flow and promotes effective mainstream-boundary flow mixing. The results indicate that the averaged surface Nusselt number consistently increases with the close time ratio and at γ = 0.9 reaches 1.9 times of the steady-flow value. Particularly the heat transfer performance inside grooves is remarkably improved by a maximum of 175%. This novel concept of synergizing flow intermittency and surface structure achieves notable heat transfer enhancement under constant coolant consumption, and shows ample design space for further optimization.

Closed Kinematic Chains and Triangular Surfaces from the Discrete Differentiable Viewpoint

Closed Kinematic Chains and Triangular Surfaces from the Discrete Differentiable Viewpoint

A novel approach for joint line restoration in revision total ankle arthroplasty based on the three-dimensional registration of the contralateral tibia and fibula

PurposeThe use of total ankle arthroplasty (TAA) is increasing over time, as so will the need for revision TAAs in the future. Restoration of the ankle joint line (JL) in revision TAA is often difficult due to severe bone loss. This study analyzed the accuracy of a three-dimensional (3D) registration of the contralateral tibia and fibula to restore the ankle joint line (JL) and reported side-to-side differences of anatomical landmarks.Methods3D triangular surface models of 96 paired lower legs underwent a surface registration algorithm for superimposition of the mirrored contralateral lower leg onto the original lower leg to approximate the original ankle JL using a proximal, middle and distal segment. Distances of the distal fibular tip, anterior and posterior medial colliculus to the JL were measured and absolute side-to-side differences reported. Anterior lateral distal tibial angle (ADTA) and lateral distal tibial angle (LDTA) were measured.ResultsMean JL approximation was most accurate for the distal segment (0.1 ± 1.4 mm (range: -3.4 to 2.8 mm)) and middle segment (0.1 ± 1.2 mm (range: -2.8 to 2.5 mm)) compared to the proximal segment (-0.2 ± 1.6 mm (range: -3.0 to 4.9 mm)) (p = 0.007). Distance of the distal fibular tip, the anterior, and posterior medial colliculus to the JL, ADTA and LDTA yielded no significant side-to-side differences (n.s.).Conclusion3D registration of the contralateral tibia and fibula reliably approximated the original ankle JL. The contralateral distal fibular tip, anterior and posterior medial colliculi, ADTA and LDTA can be used reliably for the planning of revision TAA with small side-to-side differences reported.Level of EvidenceIV.

Dr. KID: Direct Remeshing and K-Set Isometric Decomposition for Scalable Physicalization of Organic Shapes.

Dr. KID is an algorithm that uses isometric decomposition for the physicalization of potato-shaped organic models in a puzzle fashion. The algorithm begins with creating a simple, regular triangular surface mesh of organic shapes, followed by iterative K-means clustering and remeshing. For clustering, we need similarity between triangles (segments) which is defined as a distance function. The distance function maps each triangle's shape to a single point in the virtual 3D space. Thus, the distance between the triangles indicates their degree of dissimilarity. K-means clustering uses this distance and sorts segments into k classes. After this, remeshing is applied to minimize the distance between triangles within the same cluster by making their shapes identical. Clustering and remeshing are repeated until the distance between triangles in the same cluster reaches an acceptable threshold. We adopt a curvature-aware strategy to determine the surface thickness and finalize puzzle pieces for 3D printing. Identical hinges and holes are created for assembling the puzzle components. For smoother outcomes, we use triangle subdivision along with curvature-aware clustering, generating curved triangular patches for 3D printing. Our algorithm was evaluated using various models, and the 3D-printed results were analyzed. Findings indicate that our algorithm performs reliably on target organic shapes with minimal loss of input geometry.

Near-field electromagnetic scattering of Bessel vortex beam by metal target

Bessel vortex beam, as a typical vortex beam, has the characteristics of carrying orbital angular momentum (OAM), no diffraction, and self-reconstruction, which makes it more competitive than plane wave in the field of future vortex beam target detection and imaging. In order to study the near-field electromagnetic scattering of a vortex beam by a metal target, the expression of the near-scattering field of Bessel vortex beam incident on any metal target is obtained by using the physical optics method, triangular surface element modeling, and the plane wave angular spectrum expansion method of vector Bessel vortex beam. The correctness of the proposed method is verified by comparing with the simulation results of FEKO software. The amplitude distribution and phase distribution of electric field, the OAM spectrum distribution and radar cross section (RCS) of the near-scattering field of the Bessel vortex beam incident on the simple target and the combined target are calculated. The effects of beam parameters, receiving distance, target shape and the positions of beam transmitting and receiving surfaces on near-field scattering results are numerically calculated. In addition, the distributions of near-field OAM spectra under different conditions and the near-field RCS distributions of different targets are given. The numerical results show that the near-field results of Bessel vortex beam incident on metal targets are related to the beam parameters, and conform to the law of Bessel beam changing with parameters. The near-field electric amplitude distribution is affected by the distance between the receiving surface and the target, but the phase distribution is hardly affected. The near-field scattering results reflect the changes of target shape. Under normal incidence, when the target is regular and symmetrical, the amplitude distribution and phase distribution are relatively regular, and the main mode is dominant. When the beam is obliquely incident on or does not fully illuminate the target, the amplitude distribution and phase distribution change, which will lead the derived mode to increase. In particular, when the target and the receiving surface both deviate from the incident beam, the OAM disturbance is the most severe. In the near-field RCS distribution, the RCS distributions of different targets are obviously different, and the results of <i>E</i> plane and <i>H</i> plane are also different. It can be seen from the numerical calculation results that the near-field scattering of Bessel vortex beam by a metal target contains a variety of information. The application of vortex electromagnetic wave will help improve the information acquisition of electromagnetic wave and target detection capability. The results in this work can provide a reference for target imaging and vortex radar detection.

A Geometrically Exact Triangular Shell Element Based on Reproducing Kernel DMS-Splines

To model a multibody system composed of shell components, a geometrically exact Kirchhoff-Love triangular shell element is proposed. The middle surface of the shell element is described by using the DMS-splines, which can exactly represent arbitrary topology piecewise polynomial triangular surfaces. The proposed shell element employs only nodal displacement and can automatically maintain C1 continuity properties at the element boundaries. A reproducing DMS-spline kernel skill is also introduced to improve computation stability and accuracy. The proposed triangular shell element based on reproducing kernel DMS-splines can achieve an almost optimal convergent rate. Finally, the proposed shell element is validated via three static problems of shells and the dynamic simulation of a flexible multibody system undergoing both overall motions and large deformations.

Optimisation of Total Phenolic Compound Extraction and Antioxidant Activity from Dried Inflorescence of Ammi Visnaga Using Mixture Design and Triangular Surfaces

Optimisation of Total Phenolic Compound Extraction and Antioxidant Activity from Dried Inflorescence of Ammi Visnaga Using Mixture Design and Triangular Surfaces

A Numerical Investigation on Hydrothermal Performance of Micro Channel Heat Sink with Periodic Spatial Modification on Sidewalls.

Electronic gadgets have been designed to incorporating very small components such as microcontrollers, electronic chips, transistors, microprocessors, etc. These components are exceptionally heat sensitive and can be wrecked if heat is not released. As a result, the thermal control of such components is critical to their optimum performance and extended life. The use of a microchannel heat sink (MCHS) has shown promising solutions to remove the excess heat. In this paper, we have proposed a novel design of MCHS and investigated it numerically. Four different surface modifications on the sidewall of the passage, namely, extended triangular surface (ETS), extended circular surface (ECS), triangular groove surface (TGS), and the circular groove surface (CGS) in the passage of the microchannel have been exploited in the Reynolds number of 100-900. In the presence of geometrical modification, the cooling capacities have been enhanced. The results show that the Nusselt numbers of ETS-MCHS, ECS-MCHS, TGS-MCHS, and CGS-MCHS are increased by 4.30, 3.61, 1.62, and 1.41 times in comparison to the Nusselt number of MCHS with smooth passage, while the friction factor values are increased by 7.33, 6.03, 2.74, and 1.68 times, respectively. In addition, the thermohydraulic performance parameter (THPP) has been evaluated and discussed. The fact that MCHS have THPP values greater than unity demonstrates that the passage's geometries are a practical means of achieving effective thermal management.

Registration based assessment of femoral torsion for rotational osteotomies based on the contralateral anatomy

BackgroundComputer-assisted techniques for surgical treatment of femoral deformities have become increasingly important. In state-of-the-art 3D deformity assessments, the contralateral side is used as template for correction as it commonly represents normal anatomy. Contributing to this, an iterative closest point (ICP) algorithm is used for registration. However, the anatomical sections of the femur with idiosyncratic features, which allow for a consistent deformity assessment with ICP algorithms being unknown. Furthermore, if there is a side-to-side difference, this is not considered in error quantification.The aim of this study was to analyze the influence and value of the different sections of the femur in 3D assessment of femoral deformities based on the contralateral anatomy.Material and methods3D triangular surface models were created from CT of 100 paired femurs (50 cadavers) without pathological anatomy. The femurs were divided into sections of eponymous anatomy of a predefined percentage of the whole femoral length. A surface registration algorithm was applied to superimpose the ipsilateral on the contralateral side. We evaluated 3D femoral contralateral registration (FCR) errors, defined as difference in 3D rotation of the respective femoral section before and after registration to the contralateral side. To compare this method, we quantified the landmark-based femoral torsion (LB FT). This was defined as the intra-individual difference in overall femoral torsion using with a landmark-based method.ResultsContralateral rotational deviation ranged from 0° to 9.3° of the assessed femoral sections, depending on the section. Among the sections, the FCR error using the proximal diaphyseal area for registration was larger than any other sectional error. A combination of the lesser trochanter and the proximal diaphyseal area showed the smallest error. The LB FT error was significantly larger than any sectional error (p < 0.001).ConclusionWe demonstrated that if the contralateral femur is used as reconstruction template, the built-in errors with the registration-based approach are smaller than the intraindividual difference of the femoral torsion between both sides. The errors are depending on the section and their idiosyncratic features used for registration. For rotational osteotomies a combination of the lesser trochanter and the proximal diaphyseal area sections seems to allow for a reconstruction with a minimal error.

Study on the Thermohydrodynamic Friction Characteristics of Surface-Textured Valve Plate of Axial Piston Pumps.

The purpose of this paper is to study the oil film and friction characteristics of valve plates with a micro-textured surface and to explore the influence of textures of different shapes and sizes on the valve plates. Firstly, on the basis of thermohydrodynamic theory, this paper established the lubrication model of the oil film on the valve plate pair of swashplate axial piston pumps, according to the Reynolds equation. Secondly, the micro-texture was added to the mathematical model of the valve plate pair's oil film. A combination of the energy equation, oil-film-thickness equation, elastic deformation equation, viscosity-pressure and viscosity-temperature equation, the finite difference method, as well as the relaxation iteration method, was used to solve the problem, and the textured and non-textured valve plate surfaces were simulated. The nephogram of the oil-film-thickness distribution, elastic deformation distribution, oil-film-pressure distribution and oil-film-temperature distribution were generated. Then, the control variable method was used to change the cylinder rotational speed, tilt angle, oil viscosity, initial oil film thickness and other parameters to analyze their effects on oil film characteristics. In addition, the friction characteristics of non-textured surfaces, square textured surfaces, triangular textured surfaces and circular textured surfaces were compared and analyzed. It was found that the textured surface of valve plates can obviously improve friction efficiency under the same operating conditions. The square texture, especially, is the preferable shape, rather than the triangular texture and the circular texture, and the friction performance is at its best when the texture depths are between 20 μm and 50 μm. The results provide a theoretical basis for the design and improvement of the valve plate.

Physical behavior of nanoparticles-enhanced PCM including transient conduction

In this paper, numerical approach has been implemented to depict the promising efficacy of dispersion of alumina nanoparticles for expedition of freezing. The fraction and volume of powders were assumed as variables to evaluate the performance of system. The tank has sinusoidal shape and triangular cold surface has been applied as origins of solidification. The use of adaptive grid leads to better capturing the regions with higher gradient of scalar which gives higher accuracy of modeling. The precision of simulation was checked with associating the outcomes with previous data and good accommodation was reported. As alumina added in water, the period of process declines around 41.18% and optimized size of powder with highest concentration has been utilized. The time changes from 197.25 s to 157.91 s if the [Formula: see text] changes from 30 nm to 40 nm. By changing the radius of powder from 15 nm to 25 nm, the required time augments around 19.33% when [Formula: see text].

Indirect all-quadrilateral meshing based on bipartite topological labeling

Quadrilateral meshes offer certain advantages compared to triangular ones, such as reduced number of elements and alignment with problem-specific directions. We present a pipeline for the generation of quadrilateral meshes on complex geometries. It is based on two key components: robust surface meshing and efficient indirect conversion of a triangular mesh to an all-quad one. The input is a valid geometric surface mesh, i.e., a triangulation that accurately represents the geometry of the model. A right-angled triangular surface mesh is initially created by continuously modifying the input mesh while always preserving its topological validity. The main advantages of our local mesh modification-based approach are to (i) allow the generation of meshes that are globally aligned with a given direction field and (ii) to reliably handle non-manifold feature edges (in multi-volume models) and small features. The final quadrilateral mesh is obtained by merging pairs of triangles into quadrilaterals. We develop a novel bipartite labeling scheme in order to identify and correct inconsistent pairings. The procedure is based on local operations and is much more efficient than previous global strategies for tri-to-quad conversion. The whole pipeline is tested on a large number of models with diverse characteristics.