Edge Truncation Research Articles

Boundary treatments for the finite element analysis of shell vibration fields of architectural structures extracted with edge truncations

The finite element analysis of a vibration field of a large-scale architectural structure is often conducted by extracting a local part to reduce the computational cost. A common way of extraction is to truncate the structure around the junction consisting of walls and floors. This paper proposes two boundary treatments to be given to the truncated edge. One is giving an impedance boundary condition of a junction. The impedance values are determined by the transfer matrix method (TMM). The other is a non-reflecting edge truncation realized by the perfectly matched layer (PML) shell element, which is a numerical model of the infinitely extending structure. Firstly, formulations of the two treatments are provided in detail. Secondly, impedances of basic shape junctions consisting of semi-infinite members are investigated by the TMM for a better understanding of the physical behavior. Thirdly, the proposed PML element is validated in two problem settings: the distance attenuation in the free field and the cross-junction's absorption property. An appropriate parameter tuning for the calculation using the PML element is also discussed.

Observation of Topologically Distinct Corner States in “Bearded” Photonic Kagome Lattices

AbstractKagome lattices represent an archetype of intriguing physics, attracting a great deal of interest in different branches of natural sciences, recently in the context of topological crystalline insulators. Here, two distinct classes of corner states in breathing Kagome lattices (BKLs) with “bearded” edge truncation are demonstrated, unveiling their topological origin. The in‐phase corner states are found to exist only in the topologically nontrivial regime, characterized by a nonzero bulk polarization. In contrast, the out‐of‐phase corner states appear in both topologically trivial and nontrivial regimes, either as bound states in the continuum or as in‐gap states depending on the lattice dimerization conditions. Furthermore, the out‐of‐phase corner states are highly localized, akin to flat‐band compact localized states, and they manifest both real‐ and momentum‐space topology. Experimentally, both types of corner states are observed in laser‐written photonic bearded‐edge BKLs, corroborated by numerical simulations. The results not only deepen the current understanding of topological corner modes in BKLs but also provide new insight into their physical origins, which may be applied to other topological BKL platforms beyond optics.

Extremely Low-Profile Periodic 2-D Leaky-Wave Antenna: An Optimal Solution for Antenna-Frontend Integration

We investigate and present a very low-profile, high-efficiency, and high-gain 2-D leaky-wave antenna (2DLWA) implemented on a high permittivity substrate operating in the millimeter-wave range, paving the way for the seamless integration of a high-gain and high-efficiency antenna with a frontend. In contrast to the typical air-filled 2DLWA, where a perturbation of the first higher-order mode (TE1/TM1) results in highly directed broadside radiation, in the proposed antenna, the propagation and leakage of a quasi-TEM (Q-TEM) mode results in an extremely low-profile ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.065\lambda _{0}$ </tex-math></inline-formula> ), high-gain (~15 dBi) antenna. In this scenario, the transverse resonance condition for a Q-TEM mode is established by employing a capacitive partially reflective surface (PRS) in a thin ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.065\lambda _{0}$ </tex-math></inline-formula> ) substrate with a relative permittivity of 10.2. The proposed periodic 2DLWA, unlike the conventional uniform/quasi-uniform air-filled counterparts, radiates based on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {n}=-\mathbf {1}$ </tex-math></inline-formula> space harmonic operation. Due to a strong mutual interaction between the PRS and ground plane, conventional design and analysis approaches are no longer relevant in this low-profile architecture. Instead, we employ the Floquet modal expansion theory to create an equivalent circuit model (ECM) for the PRS that takes into account the contributions and mutual interactions of the Floquet harmonics as well as the ground plane effect. By employing reflecting boundaries realized with edge truncation (air trenches) in a high permittivity substrate, we show that the aperture efficiency is enhanced by 15% compared to conventional counterpart.

Topological edge states in bowtie ladders with different cutting edges

We have studied topological edge states in bowtie ladders with various edge truncations. The symmetric bowtie ladder, which comprises two trivial Su–Schrieffer–Heeger (SSH) lattices, exhibits an insulator–metal transition with trivial insulating states. On the other hand, the lattice can be transformed into an extended SSH lattice depending on the edge shapes with non-trivial insulating states in that the winding number is non-zero. The winding numbers are permutationally designated in the phase diagram depending on the choice of unit cell. The topological edge states are affected by the shape of the edge and the corresponding winding number. We also studied general bowtie ladder models with richer phase diagrams using the characteristics of the localization length of the edge states showing state bifurcation.

Classification of objects in images with distortions based on a two-stage topological analysis

The authors propose a method for automatic classification of spatial objects in images under conditions of a limited data set. The stability of the method to distortions appearing in images due to natural phenomena and partial overlap of urban infrastructure objects is investigated. High classification accuracy, when using existing approaches, requires a large training sample, including data sets with distortions, which significantly increases computational complexity. The paper proposes a method for a two-step topological analysis of images. Topological features are initially extracted by analyzing the image in the brightness range from 0 to 255, and then from 255 to 0. These features complement each other and reflect the topological structure of the object. Under certain deformations and distortions, the object preserves its structure in the form of extracted features. The advantage of the method is a small number of patterns, which reduces the computational complexity of training compared to neural networks. The proposed method is investigated and compared with the modern neural network approach. The study was performed on a DOTA dataset (Dataset for Object deTection in Aerial images) containing images of spatial objects of several classes. In the absence of distortion in the image, the neural network approach showed a classification accuracy of over 98 %, while the proposed method achieved about 82 %. Further distortions such as 90 degree rotation, 50 % narrowing and 50 % edge truncation and their combinations were applied in the experiment. The proposed method showed its robustness and outperformed the neural network approach. In the most difficult combination of the test, the decrease in classification accuracy of the neural network was 46 %, while the described method showed 12 %. The proposed method can be applied in cases with a high probability of distortion in the images. Such distortions arise in the field of geoinformatics when analyzing objects of various scales, under different weather conditions, partial overlap of one object with another, in the presence of shadows, etc. It is possible to use the proposed method in vision systems of industrial enterprises for automatic classification of the parts that belong to superimposed objects.

Modeling and visualizing of the formation of a snub dodecahedron in the AutoCAD system

The article is devoted to modeling and visualization of the formation of flat-nosed (snub-nosed) dodecahedron (snub dodecahedron). The purpose of the research is to model the snub dodecahedron (flat-nosed dodecahedron) and visualize the process of its formation. The formation of the faces of the flat-nosed dodecahedron consists in the truncation of the edges and vertices of the Platonic dodecahedron with the subsequent rotation of the new faces around their centers. The values of the truncation of the dodecahedron edges, the angle of rotation of the faces and the length of the edge of the flat-nosed dodecahedron are the parameters of three equations composed as the distances between the vertices of triangles located between the faces of the snub dodecahedron. The solution of these equations was carried out by the method of successive approximations. The results of the calculations were used to create an electronic model of the flat-nosed dodecahedron and visualize its formation. The task was generally achieved in the AutoCAD system using programs in the AutoLISP language. Software has been created for calculating the parameters of modeling a snub dodecahedron and visualizing its formation.

Spin-momentum locked interface modes based on transverse resonance and Zak phase in finite thickness dielectric slabs

The field of topological photonics has made great strides in the past decade with many new designs based on bandgap and band inversion structures that provide robust, unidirectional, and reflection-free propagation of energy. The topological invariant or Chern number of a metamaterial guarantees the existence of topologically protected edge modes. However, its mathematical application to real systems is not always straightforward and can be greatly simplified by reducing the dimensional complexity of the problem by the calculation of a Zak phase that determines the topological phase in just one dimension. This work explores two methods of creating interface modes with finite height dielectric slabs: (1) transverse resonance through variable edge truncation of a photonic crystal (PhC) or cell sliding and (2) a uni-axial topological phase by means of scaling the internal features of a unit cell. The proposed metamaterial devices use the same C4v symmetric unit cell structure on both sides of the interface and are finite in all three dimensions, allowing for easy fabrication, excitation, and implementation in real-world applications. The all-dielectric design also enables an easy transition to and from conventional PhC waveguides and lends itself well to operation in frequencies spanning across the microwave and optical spectrum without concerns of additional metallic losses in the THz region.

Орудия из кости в комплексах среднего и верхнего палеолита Денисовой пещеры: материалы 2021 года

The article presents the results of unshaped and formal bone tools investigation from the Pleistocene deposits found in the south gallery of Denisova Cave. Bone retouchers of the Late Middle and Early Upper Paleolithic were found in layers 12 and 11, respectively. It has been established that, compared to the Middle Paleolithic retouchers, tools of this type from layer 11 are distinguished by the shaping processing of bone blanks. Fragments of diaphysis have traces of deliberate truncation of transverse edges, trimming of longitudinal edges, removal of sharp edges of fractures by retouching. In addition to the percussion technique, these retouchers were also used for pressure technique retouching, which is consistent with tool samples from the accompanying lithic industry. Formal bone tools from layer 11 include two intact and fragmented polishers, two pins, an awl fragment, a perforator, an eyed needle, and an indeterminate tool blank. These tools were used mainly at various stages of the tanning production: polishers were used for primary processing of hides in order to soften them and remove the hide cuttings, an awl and perforator—for perforating a relatively thick or thinner hide, a needle—when stitching a carefully finished material, stringing or attaching ornaments to clothes. The detailed analysis made it possible to identify a characteristic set of wear signs on each of the tools indicating their long-term use. The toolkit is supplemented by unique bone pins, which, based on the nature of processing and traces of disposal, could have been used to fasten various parts of the costume of the Upper Paleolithic inhabitants of Denisova Cave.

Visualizing surface formation of semi-regular polyhedra of Archimedes

The most common method of forming semi-control polyhedra consists in cutting off angles and ribs of regular polyhedra by planes. The aim of the work - to consider the automated formation of a number of surfaces of semi-regular Archimedean polyhedra based on the dodecahedron. These include the truncated dodecahedron, the icosododecahedron, the romboicosododecahedron and the truncated icosododecahedron. The formation of surfaces is carried out by the kinematic method in AutoCAD using programs compiled in the AutoLISP language. Methods. The methodology for the formation of these polyhedra provides for truncation of the angles and edges of the dodecahedron. This requires the calculation of a number of geometric parameters of these polyhedra and dodecahedron, such as the value of the truncation of the dodecahedron edges, the size of the edges of truncated polyhedra, the centers of faces, dihedral angles, etc. In order to generate these surfaces, a frame is constructed because the frame lines are used as guides to form surfaces in a kinematic way. The electronic model of each polyhedron is constructed as a set of compartments of surfaces of all its faces, and each compartment is assigned to a certain layer of the drawing. The frame and electronic model of the polyhedra under study are formed by means of user programs composed in the functional language AutoLISP. The process of forming surfaces of selected polyhedra in the AutoCAD environment is provided by special programs that are also compiled in the AutoLISP language. Results. Software was created to demonstrate the process of formation of a number of Archimedes polyhedra on the monitor screen.

Reshaping of Truncated Pd Nanocubes: Energetic and Kinetic Analysis Integrating Transmission Electron Microscopy with Atomistic-Level and Coarse-Grained Modeling.

Stability against reshaping of metallic fcc nanocrystals synthesized with tailored far-from-equilibrium shapes is key to maintaining optimal properties for applications such as catalysis. Yet Arrhenius analysis of experimental reshaping kinetics, and appropriate theory and simulation, is lacking. Thus, we use TEM to monitor the reshaping of Pd nanocubes of ∼25 nm side length between 410 °C (over ∼4.5 h) and 440 °C (over ∼0.25 h), extracting a high effective energy barrier of Eeff ≈ 4.6 eV. We also provide an analytic determination of the energy variation along the optimal pathway for reshaping that involves transfer of atoms across the nanocube surface from edges or corners to form new layers on side {100} facets. The effective barrier from this analysis is shown to increase strongly with the degree of truncation of edges and corners in the synthesized nanocube. Theory matches experiment for the appropriate degree of truncation. In addition, we perform simulations of a stochastic atomistic-level model incorporating a realistic description of diffusive hopping for undercoordinated surface atoms, thereby providing a visualization of the initial reshaping process.

Design modifications and multilayer impact in the electronic parameters of printed graphene patch antenna

The stack antenna technique used to improve the antenna characteristics of the printed patch antenna structures. The method of stacking varies for each material. In this work we used graphene as the radiating material. The improvement in the parameters is achieved by edge truncation and ground plane optimization techniques. The main factor to affect the stacking is the curing temperature and the heat absorbing nature of the substrate and air gap between layers. In this work we have experimented and analysed the effect of multilayer stacking on printed antenna structures and its effect on the antenna performance. The antenna is designed for 2.45 GHz ISM Band applications and the gain is more than + 5 dB. In this paper we tried to replace the copper with multilayer graphene based printed structure.

Theoretical Prediction of the Distribution of Spin Moment on Metal-N-C Catalyst Embedded in Truncated Graphene Sheets

As a pristine graphene nanostructure, zigzag graphene nanoribbons (ZGNRs) has received considerable interest over the past decade due to the presence of polarizable edge states1. It has also been employed as a model system for non-precious metal catalysts since it can host a variety of active sites2. Among various classes of catalysts, metal (Me) and nitrogen co-doped graphene has been emerging as promising electrocatalysts in oxygen reduction reaction (ORR). Furthermore, it has also been shown that porphyrin-like Me vacancy embedded in graphene is more stable at edges than far-away from the edges3. In the light of those recent studies, the change of spin states on the edge and in the bulk caused by Fe and N co-doping is an essential factor to tune the electronic and magnetic states on graphene. Therefore, unraveling spin interactions between co-doped metal-nitrogen complex and edge states (illustrated in Fig. 1) can control the electronic conductivity of doped graphene sheets and electron density at metal active sites, which is essential for their applications in electrocatalysts. In this work, the effect of nitrogen-metal and vacancies in the bulk and edge configurations on the spin polarization on graphene materials will be presented as obtained from two computational methodologies: plane waves and atomic-centered Gaussian functions. There are some drawbacks on each DFT code regarding magnetic calculations. Sensitivity of the value of total magnetic moment in VASP obtained from Bravais lattice depends on k-point sampling, smearing parameters and stress applied to unit cell. On the other hand, the initial spin moment guess on each atom is not implemented on deMon2k to be able to obtain anti-ferromagnetic states of graphene. Finally, the ORR reactivity as a function of (a) the metal location in graphene and (b) the edge truncations will be discussed. Figure 1: Suppression of spin polarization in edge modification by Fe N4 Acknowledgement: This work is supported by the LabEx CheMISyst ANR-10-LABX-05-01. References Son, Y.-W.; Cohen, M. L.; Louie, S. G. Half-metallic graphene nanoribbons. Nature 2006, 444, 347 Zitolo, A. et al. Identification of catalytic sites for oxygen reduction in iron- and nitrogen-doped graphene materials. Nature Materials 2015, 14, 937–942 Holby, E. F.; Taylor, C. D. Control of graphene nanoribbon vacancies by Fe and N dopants: Implications for catalysis. Appl. Phys. Lett. 2012, 101, 064102 Figure 1

Diffraction by a truncated planar array of dipoles:A Wiener–Hopf approach

We present a rigorous solution to the problem of scattering of a semi-infinite planar array of dipoles, i.e., infinite in one direction and semi-infinite in the other direction, thus presenting an edge truncation, when illuminated by a plane wave. Such an arrangement represents the canonical problem to investigate the diffraction occurring at the edge-truncation of a planar array. By applying the Wiener–Hopf technique to the Z-transformed system of equations derived from the electric field integral equation, we provide rigorous close form expressions for the dipoles’ currents. We find that such currents are represented as the superposition of the infinite array solution plus a perturbation, which comprises both edge diffraction and bound surface waves excited by the edge truncation. Furthermore, we provide an analytical approximation for the double-infinite sum involved in the calculation which drastically reduces the computational effort of this approach and also provides physically-meaningful asymptotics for the diffracted currents.

Textile Antenna With Simultaneous Frequency and Polarization Reconfiguration for WBAN

This paper proposes the design of a reconfigurable circularly polarized textile antenna. The circular polarization feature in the proposed antenna is generated by the edge truncation of a rectangular patch and the incorporation of a slotted ground plane, whilst the frequency reconfigurability feature is realized by slot size modification via the use of three embedded RF p-i-n diode switches. Consequently, the antenna operation can be switched between six frequencies (1.57, 1.67, 1.68, 2.43, 2.50, and 2.55 GHz) depending on the seven switch configurations. The proposed antenna is validated experimentally to be operable within the WBAN, WLAN, and GPS range in a compact and wearable format, with gains of up to 4.8 dBi.

The Rome de Lisle problem.

The `Rome de Lisle problem' on the vertex and edge truncations has been formulated and solved for all crystal closed simple forms (two, eight, five and 15 for orthorhombic, trigonal + hexagonal, tetragonal and cubic syngonies, respectively). The collections of simple forms obtained are enumerated and considered as special combinations of simple forms in symmetry classes.

Correlation of edge truncation with antibacterial activity of plate-like anisotropic silver nanoparticles.

The effect of silver nanoparticle anisotropy on the antibacterial properties has been studied against Escherichia coli, Staphylococcus aureus, Bacillus, Vibrio cholerae, and Streptococcus pyogenes. Anisotropic silver nanoparticles have been synthesized by solvothermal process. The UV-visible absorption, X-ray diffraction, and TEM studies show the anisotropic nature of silver nanoparticles. The results demonstrate that the anisotropic silver nanoparticles undergo a shape-dependent interaction with the bacteria, and the nanoparticles with higher anisotropy exhibit the superior antibacterial activity. Silver nanoparticles with sharp edges and corners displayed the stronger biocidal action, in comparison to the anisotropic nanoparticles with round edges and corners. The sharpness of the corners has been quantified using degree of truncation method. The variation in degree of truncation and the antibacterial activity follows the same pattern.

Metamaterial‐inspired printed UWB antenna for short range RADAR applications

AbstractThis research article presents a novel design of printed antenna for 24 GHz ultra‐wideband (UWB) applications. This research develops an antenna having dimension of 5 × 6 × 0.8 mm3 which operates from 24 to 30 GHz. This is achieved using techniques such as truncation of patch edges and inclusion of complementary split ring resonator metamaterial (MTM). This antenna can be used for short range RADAR application at 24 GHz UWB for automotive appliances. This article includes the detailed investigations such as surface current distribution on antenna, far field patterns, gain, group delay and radiation efficiency over frequency, as well as measurement details. Simulation and measurement data on return loss have shown good equality which proves the feasibility of the proposed antenna.

A Sequentially Rotated, Circularly Polarized Microstrip Antenna Array with Reduced Mutual Coupling

ABSTRACTA circularly polarized microstrip patch antenna array with sequential rotation and reduced mutual coupling between its elements is proposed. A microstrip patch modified to suppress surface waves is used as the array element. The modifications include the addition of shorting pins and inclusion of a slot and edge truncations to produce a circularly polarized array element that does not excite surface waves. The designed element has higher gain and a more directional radiation pattern than a similar conventional microstrip patch antenna. In order to improve circular polarization bandwidth, sequential rotation techniques using the proposed microstrip antenna were investigated. Surface wave supersession of a 2 x 2 sequentially rotated array using the proposed design was achieved throughout the entire axial ratio bandwidth. One-layer directly fed array and two-layer aperture coupled array were investigated. The two-layer design achieved better impedance and axial ratio bandwidths than the single layer design. The design procedure, simulation results, and experimental measurements are presented.

Mathematics, Models, and Magz, Part II: Investigating Patterns in Pascal's Simplex

SummaryThis paper is a sequel to Mathematics, models, and Magz, Part 1: Investigating patterns in Pascal's triangle and tetrahedron. In the current paper the authors use a set of magnetic toys to extend results of Part I about patterns concerning binomial and tetranomial coefficients. In Pascal's tetrahedron they study vertex truncations and edge truncations. Then they extend those ideas to obtain analogous results in Pascal's simplex.

Shape-Dependent Activity of Ceria in Soot Combustion

In this study, a series of conventional polycrystalline ceria and single-crystalline ceria nanorods and nanocubes were prepared by hydrothermal methods, and their structural, redox, and morphological properties were investigated using XRD, SEM, HRTEM, BET, temperature-programmed reduction, and oxygen storage capacity measurements. According to HRTEM, they are characterized by exposure of different surfaces: {100} surface for nanocubes; {100}, {110}, and in part {111} for nanorods; and mainly {111} for conventional polycrystalline ceria, with a morphology dominated by {111}-enclosed octahedral particles. The presence of more-reactive exposed surfaces affects the reaction of soot oxidation positively, with an increase in activity in nanoshaped materials compared with conventional ceria. Thermal aging, although detrimental for surface area, is shown to affect morphology by promoting irregular truncation of edges and corners and development of more reactive surface combinations in all crystal shapes. It is li...