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Mathematical analysis on electromagnetic waves in photonic graphene, a photonic topological material which has a honeycomb structure, is one of the most important current research topics. By modulating the honeycomb structure, numerous topological phenomena have been observed recently. The electromagnetic waves in such media are generally described by the 2-dimensional wave equation. It has been shown that the corresponding elliptic operator with a honeycomb material weight has Dirac points in its dispersion surfaces. In this paper, we study the time evolution of the wave packets spectrally concentrated at such Dirac points in a modulated honeycomb material weight. We prove that such wave packet dynamics is governed by the Dirac equation with a varying mass in a large but finite time. Our analysis provides mathematical insights to those topological phenomena in photonic graphene.

Wireframe DNA origami has emerged as a powerful approach to fabricating nearly arbitrary 2D and 3D geometries at the nanometer-scale. Complex scaffold and staple routing needed to design wireframe DNA origami objects, however, render fully automated, geometry-based sequence design approaches essential for their synthesis. And wireframe DNA origami structural fidelity can be limited by wireframe edges that are composed only of one or two duplexes. Here we introduce a fully automated computational approach that programs 2D wireframe origami assemblies using honeycomb edges composed of six parallel duplexes. These wireframe assemblies show enhanced structural fidelity from electron microscopy-based measurement of programmed angles compared with identical geometries programmed using dual-duplex edges. Molecular dynamics provides additional theoretical support for the enhanced structural fidelity observed. Application of our top-down sequence design procedure to a variety of complex objects demonstrates its broad utility for programmable 2D nanoscale materials., Wireframe DNA origami is a powerful approach to creating 2D and 3D geometries. Here the authors introduce an automated computational design approach that programs structures with high structural fidelity.

For the first time, the acoustic characteristics of a full-scale double-layer sample of acoustic liner were determined by numerical simulation of physical processes in an normal incident interferometer. The double-layer liner sample consisted of 14 honeycomb cells and 70 perforation holes. The dimensions of the honeycomb cells and perforation holes correspond to the acoustic liners used in the ducts of aircraft engines. Numerical simulation was carried out based on solution of the unsteady Navier-Stokes equations in three-dimensional formulation. A high degree of agreement of the acoustic characteristics obtained by numerical simulation with experiment was noted.

Aluminium honeycomb is a light weight, thin-walled material with a typical multi-cellular construction and a good strength-to-weight ratio. Therefore, aluminium honeycomb can be used as an energy-absorbing device for high-speed trains. Due to its large mass and high operating speed, a high-speed train can generate large impact energy. Thus, an energy-absorbing device with a greater energy absorption capability must be designed for high-speed trains. To reduce the aerodynamic drag, the cross-sectional area of a high-speed train is limited. Therefore, a honeycomb energy-absorbing device should be designed in such a way that it is longer than the traditional energy-absorbing devices; however, this may lead to bending, destruction and uncontrollable deformation of the honeycomb; these factors are not conducive for energy absorption. In this paper, a sleeve structure was designed for high-speed trains, and a crash experiment of the energy-absorbing structure showed that the bending and destruction of the honeycomb energy-absorbing device are effectively suppressed compared with the ordinary honeycomb energy-absorbing structure. Moreover, the fluctuation of the crash force was smaller and the crash force is more stable than the traditional thin-walled energy-absorbing structure. Therefore, the deformation instability problem of the ordinary honeycomb energy-absorbing structure and the crash force fluctuation problem of the traditional thin-walled energy-absorbing structure can be solved. Then, a crash experiment and simulation involving a high-speed train with improved honeycomb energy-absorbing device was carried out, and the results showed that the deformation of the end of the train body was stable and controllable, and the train body deceleration satisfied the collision standard EN15227.

Graph theory has made much advancement in the field of mathematical chemistry in last few decades. Now a days, chemical graph theory has become very popular among researchers because of its...

Bio-inspired engineering designs have gained great attention due to their excellent structural and mechanical properties. To study the hierarchical structural characteristics of natural structures,...

Sandwich steel doors are used for domestic and commercial purposes. The structure of this door consists of steel sheet and paper honeycomb sandwiched and bonded to steel sheets for light weighting. These doors experience dent frequently during their regular usage. However, for such products currently there are no available standards for dent characterization. In the present work, a novel experimental method has been proposed to characterize the dent and evaluate its performance. Based on experimental results, low-cost design modification is also proposed to enhance the dent performance of the door. A method is established to use the coupon samples to evaluate the door dent performance instead of full-scale experimentation.

A series of solid acid catalysts such as ZrO2, Mo(VI)/ZrO2 and W(VI)/ZrO2 have been coated on honeycomb monoliths as well as synthesized in the powder forms and used as catalytic materials for synthesis of ethyl levulinate from levulinic acid and ethanol. These solid acids were characterized by BET, NH3-TPD/n-butyl amine back titration, FTIR, PXRD and SEM techniques. Effects of various reaction parameters towards the reaction performance were studied. The performance of the catalyst was tested based on nature of the catalyst (honeycomb coated or powder form), reaction time (1 to 5 h), molar ratio (1:1 to 1:12 levulinic acid to ethanol) and reusability of the catalytic material. An excellent yield (86-88 %) of ethyl levulinate was obtained under optimized conditions. An attempt is made to correlate the activity of the catalysts in this esterification reaction with their surface characteristics. The honeycomb monoliths coated with zirconia and its modified forms were found to be ecofriendly, cost-effective and reusable catalytic materials compared to their powder forms.

The vibration transmissibility of paper honeycomb sandwich plate was tested and the vibration transmissibility curve was simplified and characterized. Based on the basic principle of vibration mechanics, the equation for calculating the energy dissipated by damping of paper honeycomb sandwich plate-block system during vibration was deduced. Furthermore, the effects of honeycomb structural parameters (cell length, sandwich plate thickness) and block mass on the damping energy dissipation were analyzed. The results showed that the curves of vibration transmissibility for paper honeycomb sandwich plate can be divided into three regions: plateau region, amplification region, and attenuation region. The vibration transmissibility ratio in different regions can be expressed as functions of frequency. The energy dissipated by damping of paper honeycomb sandwich plate-block system depends on its vibration transmissibility. If the vibration transmissibility ratio–frequency curve is obtained, the damping energy dissipation of the system can be calculated. The total energy dissipation of paper honeycomb sandwich plate-block system during vibration is about equal to that of plateau region, and the energy dissipated in amplification and attenuation region can be neglected. Different honeycomb structural parameters have the same effect on the damping energy dissipation of the system. Block mass has little effect on the damping energy dissipation in plateau region and the total energy dissipation during vibration but has a greater impact on the energy dissipation in the amplification and attenuation regions. The purpose of this paper is to provide a basic method for calculation of energy dissipated by damping and evaluation of anti-vibration property for packaging material.

This paper is a mathematical analysis of conduction effects at interfaces between insulators. Motivated by work of Haldane-Raghu , we continue the study of a linear PDE initiated in papers of Fefferman-Lee-Thorp-Weinstein. This PDE is induced by a continuous honeycomb Schrodinger operator with a line defect. This operator exhibits remarkable connections between topology and spectral theory. It has essential spectral gaps about the Dirac point energies of the honeycomb background. In a perturbative regime, Fefferman-Lee-Thorp-Weinstein construct edge states: time-harmonic waves propagating along the interface, localized transversely. At leading order, these edge states are adiabatic modulations of the Dirac point Bloch modes. Their envelops solve a Dirac equation that emerges from a multiscale procedure. We develop a scattering-oriented approach that derives all possible edge states, at arbitrary precision. The key component is a resolvent estimate connecting the Schrodinger operator to the emerging Dirac equation. We discuss topological implications via the computation of the spectral flow, or edge index., Comment: 61 pages; 11 figures

The aim of this work is to evaluate the mechanical properties and failure analysis of cellular core structures with different geometries that were obtained by additive manufacturing. Sandwich panels are widely used in the aerospace and automotive industry. In general, the core of the panels is made of a two dimensional cellular with a honeycomb geometry. With the development of additive manufacturing methods it is possible to produce samples with complex geometries which may compete with conventional designs. Thus an investigation was conducted to evaluate the mechanical behavior of three core geometries, specifically, regular honeycombs, lotus and hexagonal honeycombs with Plateau borders. Samples were produced in PLA (polylactic acid) by fused deposition modelling (FDM). Experimental compressive loading in three different directions, and finite element simulations of the samples permit to evaluate their deformation and failure mechanisms. Load direction angles were found to have a strong influence in the failure mode. Among the three structures, and for the same relative density, the lotus geometry exhibited the highest stiffness and strength. However, the absorbed energy was found to be higher for honeycomb, at two loading directions. Some of the structures studied may be alternative to conventional designs pursuing the strategy of design with low weight and high stiffness.

Honeycomb absorbing materials are anisotropic structural materials. Depending on the size of honeycomb lattices, the absorbent content of the impregnated layer is different, the thickness of the impregnated layer is different, and the absorbing function of the impregnated honeycomb absorbing materials is also different. For the characterization of electromagnetic parameters of honeycomb absorbing materials, this paper adopts free space method for testing, uses CST software for modeling, and inverts the electromagnetic parameters of honeycomb absorbing structures. The absorbing performance of single-layer and double-layer honeycomb sandwich structures was simulated by RAM Optimizer software. The research shows that the height of the single-layer honeycomb absorbing material is 22mm. When the absorber content is 65%, 75% and 85% respectively, the harmonic peak moves slightly to the low frequency electromagnetic wave with the increase of the absorber content, but the absorbing strength decreases with the increase of the absorber content. For the double-layer honeycomb sandwich structure, the difference of absorber content in the upper and lower honeycomb absorbing materials is smaller, and the absorbing performance is stronger. When the thickness of the wave-transparent panel is thinner, the harmonic peak of the absorbing curve moves slightly to the high frequency.

Assembled aluminium honeycomb sandwich panels (AAHSP) can be used as urgent repair and construction materials for airport runways. To verify the feasibility of using this type of pavement structure...

The great success of graphene has spurred huge interest in two-dimensional honeycomb lattices of post-carbon group-14 atoms, namely, Xenes. However, the synthesis of Xenes on supporting substrates ...

To meet the requirements of passive safety protection during vehicle collision, a honeycomb-filled composite energy absorber (HFCEA) was designed in this study. A finite element model was establish...

Innovative honeycomb-based structures have been paid substantial attention in recent years due to their superb mechanical performances and specific functions. The presented study made acomprehensive overview on the development of the innovative honeycomb-based structures in the past two decades, including filled-type, embedded, tandem, hierarchical, auxetics with Negative Poisson's Ratio (NPR), etc. Mechanical performances of these structures were commented with advantages and disadvantages, related on their geometric configurations, mechanical performance and dynamic response, respectively. The challenges as well as future directions were also analyzed. The achievements provide significant guidelines in designing of new generation light-weight honeycomb-based structures.

Honeycomb sandwich structures have been extensively investigated in the past decades. A kind of innovative honeycomb sandwich with ceramic tile (ceramic sandwich), was investigated here for its bending behavior by using finite-element model implemented in Abaqus/Explicit code. In our studies, a series numerical simulations of three-point bending were carried out for the ceramic sandwich and conventional aluminum honeycomb sandwich. Their numerical models were validated by experiments. As confirmed that the ceramic tile largely enhances the stiffness of the structure, which contributes a lot to the promotion of the bending resistance capacity. Parametric studies were performed to further investigate the effects brought from the ceramic tile and honeycomb core in terms of changing the thickness of ceramic tile, the thickness of honeycomb wall, the length of honeycomb cells. It was found that the bending performance heavily relay on the geometric configuration of the present sandwich panel. In addition, the ceramic sandwich with reinforced honeycomb core also shows better mechanical behavior in the simulation. All these achievements provide more likelihood of designing composited high-performance sandwich.

In this article, a decahedral honeycomb sandwich panel structure with periodic internal resonators is developed to effectively mitigate the impact force and dissipate the impact energy. Five types ...

In view of the cumbersome and sultry problem of thermal protective clothing, this study proposes a new method to optimum the protection and comfort properties of the multilayer fabric systems by changing the structure of a separate fabric layer. This research applied the honeycomb structure into thermal liner of multilayer fabric systems in thermal protective clothing. In the study, the experimental samples included 48 honeycomb sandwich structures and 4 traditional structures. A thermal protective performance tester was applied to measure the thermal protective performance provided by these fabric systems and the influence of honeycomb parameters on thermal performance was studied. The results show that the honeycomb sandwich structure fabric systems are lighter in weight and more comfortable to wear than traditional fabric systems. The core thickness plays a dominant role in the thermal protective performance of honeycomb sandwich structure fabric. Additionally, the honeycomb's side length and wall thickness both affected the thermal protection performance of the fabric system. Increasing wall thickness as well as decreasing the side length can improve the thermal protective performance of honeycomb sandwich structure fabric system. Finally, by comparing the thermal protection performance growth rate ratio, an optimal solution was found (core thickness: 2.04, side length: 2, and wall thickness: 7.8). Research on the thermal protection performance of honeycomb sandwich fabric systems helps to provide appropriate guidance to improve thermal protection and reduce heat burden by means of structural effects that affect heat transfer.

In this article, the crashworthiness of a crisscross-reinforced square honeycomb under out-of-plane crashing was investigated theoretically and numerically. The square honeycomb is formed b...

This work was financially supported by the National Natural Science Foundation of China (NSFC; nos. 21875112 and 21576139), the Natural Science Foundation of Jiangsu Province (BK20180154), the National and Local Joint Engineering Research Center of Biomedical Functional Materials, and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

The general magnetic characterisation of a series of materials in the BaNi2V2O8-BaNi2P2O8 layered honeycomb spin-1 system is reported. A change from dominantly 2-dimensional (2D) to dominan...

The results of the numerical determination of the stress-strain state of the composite honeycomb panel under thermal loads of varying intensity in a near-earth orbit are presented. As a simulation model of the structure under study, a typical structure of a composite cell panel with a known type of cell arrangement of honeycomb aluminum filler and reinforcement schemes for layers of carbon fiber material for upper and lower plates with known thermomechanical properties was chosen. To solve the problems of thermoelasticity, we used the finite element method in mathematical formulations for quasistatic thermomechanical analysis. The distribution of the values of von Mises equivalent stresses in the structural elements of the honeycomb panel under thermal loads in the temperature range from -80 to +80 is determined. The longitudinal and transverse deflections of the honeycomb from the action of thermal loads of various intensities in the near-earth orbit are found. The limiting value of the temperature difference between the outer surfaces of the plates, which ensures the thermal stability of the composite honeycomb panel, has been established.

Recently, more and more attentions have been paid to structural defect suppression. In this study, branch point algorithm was first constructed for structural irregularity determination of honeycomb structure, so as to identify the geometric defect of similar cellular structures. Detailed principle and process were presented with key steps as image binarization, smoothing & noise suppression, skeletonization, vertex identification and cell reconstruction. A representative illustration was given. Afterwards, the routine difference has been discussed between the present method and classic Harris algorithm. Some examples in different cases were presented. As the findings turned out that, the branch point algorithm efficiently identifies the vertices of each cell with high precision, even in cases of poor images with low resolution. All these achievements pave a way for high standard honeycomb structure in consistency, reliability and homogeneity.

Weights of honeycomb sandwich composite structures are strictly controlled in scenarios such as in contexts of aerospace engineering. However, such structures extensively studied in past investigat...

The self-assembly of 3,10-dibromo-perylo[1,12-b,c,d]thiophene on Ag(111) leads to three types of ordered porous networks: honeycomb PN1, Kagome PN2, and hybrid PN3. Detailed experimental and theore...

Chiral, star honeycomb, and re-entrant structures are among the most important structures of auxetic materials. In this study, a dense re-entrant unit cell is introduced for making a 3D auxetic structure to be used in high stiffness applications. A re-entrant structure is chosen due to its fundamental characteristics underlying the main characteristics of auxetic structures. The energy methods of solid mechanics along with numerical methods are used to study the fundamental concept of auxetic structures. Understanding the characteristics of the re-entrant structure will lead to the better comprehension of other structures of auxetic materials, which will eventually contribute to the advance of research in this new class of materials.

The objectives of this study were (a) to compare the effectiveness of the two methods of pedigree selection in barley: the ear-to-row classical pedigree method and the honeycomb method and (b) the evaluation of the selection criteria of the honeycomb methodology. Five F12 lines developed by classical pedigree method were used as checks in order to compare seven lines developed by honeycomb methodology. Five honeycomb pedigree lines were selected by PYI basic selection criterion of honeycomb methodology and two more (rejected by PYI) were selected by YC, a new criterion proposed for improving selection of high yielding plants in honeycomb design. Also, the original local population from which all these lines were derived and two commercial barley cultivars were used as the basic checks. All genotypes selected by classical and honeycomb pedigree method out yielded the original local population. Many of them reached or out yielded the commercial cultivars used as checks and thus both classical and honeycomb pedigree methods were able to promote some homozygous genotypes in order to be used as new cultivars. Yield performance of progeny lines selected by classical pedigree method was better than honeycomb’s. Only when YC was used as selection criterion honeycomb pedigree lines showed high yielding performance. Comparing PYI and YC selection criteria, it seems that the second is better for promoting high yielding and stable lines for next generations to be used as future new cultivars. Grain yield and bulk density are safer traits than 1000-kernel weight, for efficient selection that ensures high and stable yields.

This paper investigates the nonlinear bending behavior of sandwich beams with functionally graded (FG) negative Poisson’s ratio (NPR) honeycomb core in thermal environments. The novel constructions of sandwich beams with three FG configurations of re-entrant honeycomb cores through the beam thickness direction are proposed for the first time. The temperature-dependent material properties of both face sheets and core of the sandwich beam are considered. 3D full scale finite element analyses are conducted to investigate the nonlinear bending behavior and the variation of effective Poisson’s ratio (EPR) of the sandwich beam in the large deflection region. The numerical simulations are carried out for the sandwich beams with FG-NPR honeycomb core, from which results for the same sandwich beam with uniform distributed NPR honeycomb core are obtained as a comparator. Finite element results showed that the thickness change of sandwich beams with NPR honeycomb cores are distinctly out of ordinary, and the NPR sandwich beams have significantly lower load-bending moment curves compared with those with positive Poisson’s ratio cores. The effects of functionally graded configurations, load distribution types, boundary conditions, temperature changes and length-to-thickness ratios on the bending load-deflection curves and EPR-deflection curves of sandwich beams are discussed in detail.

This paper investigates the thermal post-buckling behavior of sandwich beams with functionally graded (FG) negative Poisson's ratio (NPR) honeycomb cores. Two symmetric FG configurations of re-entrant honeycomb cores along the beam thickness direction are proposed for the first time. The material properties of both face sheets and core of the sandwich beams are assumed to be temperature-dependent. The thermal post-buckling behavior and the variation of effective Poisson's ratio (EPR) of the sandwich beam in the large deflection region are studied by using 3D full scale finite element simulations. Numerical results are presented for the sandwich beams with FG-NPR honeycomb core under a uniform temperature field, from which results for the same sandwich beam with uniform distributed NPR honeycomb core are obtained as a comparator. The EPR-deflection curves are obtained for the first time, and the results reveal that greater bending stiffness could bring about higher EPR-deflection curve. The effects of functionally graded configurations, boundary conditions, facesheet-to-core thickness ratios, cell wall-to-facesheet thickness ratios and length-to-thickness ratios on the thermal post-buckling load-deflection curves and EPR-deflection curves of sandwich beams are discussed in detail.

The acoustic characteristics of a full-scale sample of an actual single-layer liner are determined by numerical simulation of physical processes in normal incidence interferometer. Numerical simulation is performed based on solving the unsteady Navier-Stokes equations with allowance for compressibility in three-dimensional statement. It is noted the good agreement of the acoustic characteristics of the liner sample obtained in numerical simulation and in experiment. It is shown that conducting numerical simulation on single cell sample of the liner also gives results that are in good agreement with the experiment. It allows predicting the acoustic characteristics of samples of locally reacting liners with a more complex geometry in further.

In order to obtain honeycomb structure with higher energy absorption capacity, a novel honeycomb is proposed by adding double arrowhead honeycomb (DAH) cells into star-shaped honeycomb (SSH), and therefore named as star-arrowhead honeycomb (SAH). An analytical model is built to investigate the in-plane elastic properties of the newly proposed honeycomb and the results are in good agreement with the finite element simulations. The in-plane dynamic crushing behaviors and energy absorption capabilities of SAH are studied systematically by finite element method and are compared with that of SSH and DAH. Two plateau stress regions in the stress–strain curves of SAH are observed under low-velocity impact loading, and the second plateau stress is over three times higher than the first one. The in-plane Poisson's ratio of SAH under static and high-velocity impact loading always shows negative value. However, the Poisson's ratio of SAH changes from negative to positive under low-velocity and medium-velocity impact loading. In addition, the Poisson's ratio of SSH and DAH are negative during the entire dynamic deformation processes. The results of finite element simulations show that SAH can absorb much more energy than SSH with the same relative densities under different impact velocities, especially under low-velocity impact loading. Furthermore, the effects of the cell wall thickness and the impact velocity on plateau stress of SAH are discussed, and therefore a deformation map is summarized. It can be concluded that SAH is a better choice for energy absorption. This study may provide a new design concept for the high performance honeycomb structure with multi plateau stress regions.

The present study aims to investigate the moisture management and wicking properties of eri knitted fabrics. In this study, two different knit structures, namely, single pique and honeycomb fabric,...

The structures of a sandwich composite have been utilized in the aerospace industry andengineering applications. Prediction of a theoretical composite construction's flexuralproperties is important for efficient composite products design. In this investigation, fourdifferent core shapes were used in the fabrication of the sandwich frames with constantvolume of sandwich composite structure in each case; these are hexagonal, rectangular,triangular and circular. The effect of core stiffeners number was studied to finding the beststiffeners number which gives the highest properties in strength using the finite elementanalysis.The material of the each face sheet is consisting from epoxy with four layers of a wovenfiberglass laminate construction, and the core stiffener material consists from epoxy matrixwith carbon fiber, the fiber volume fraction was 60% for both skins and core composites.The analysis of the three point bending load with a value of (10 kN) conducted byconstructing a finite element model, explained that the best shape of core was rectangularwhich give less deflection value of (11.939 mm) from the other shapes, for the sameproperties of material and constant core volume in each case. Also, it was determined theoptimum stiffeners number, for the rectangular core, was five stiffeners in longitudinaldirection and twelve stiffeners in transverse direction, gives strengthen structure.

Due to increased attention to safety requirements, energy absorbents such as honeycomb structures have gained increased importance. This study proposes a design for a graded honeycomb struc...

In this paper, we designed a two-dimensional honeycomb monolayer ZrB2C2, which is predicted to be a stable nanosheet and exhibits favorable mechanical and thermal properties. The Young's modulus of ZrB2C2 is 122.3 N m-1, which is about one third of that of graphene. The ab initio molecular dynamics (AIMD) results show that ZrB2C2 can sustain up to 500 K. In addition, ZrB2C2 is semi-metallic and it exhibits twelve Dirac cones in the first Brillouin zone; the six pairs of Dirac cones form compensated electron-hole pockets, and the maximum Fermi velocity is about 6.3 × 105 m s-1, which is about 60% of that of graphene. Compared with other transition metal borides which possess Dirac states, the twelve Dirac cones are all robust under different types of external strains, and the Dirac states could be shifted along the opposite direction crossing the Fermi energy barrier by external strains and the gap of the two Dirac cones could be opened around the Fermi energy level with the effect of spin-orbit coupling.

The fabric developed from honeycomb weave is a multilayer fabric having variable strength and elongation. Properties of these structures depend on the cell size of the honeycomb weave. The aim of the research is to identify the effect of cell size on the tensile strength in terms of breaking force and elongation of the honeycomb weave structures. In this paper, three different cell sizes of honeycomb fabrics were created and analysed in both warp and weft direction for its tensile properties. Analysis shows significant results in the warp direction and weft direction of honeycomb fabric.

Topological indices are the numerical values associated with chemical structures that correlate physico-chemical properties with structural properties. There are various classes of topological indices such as degree based topological indices, distance based topological indices and counting related topological indices. Among these classes, degree based topological indices are of great importance and play a vital role in chemical graph theory, particularly in chemistry. In this report, we have computed the multiplicative degree based topological indices of honeycomb derived networks of dimensions I, 2, 3 and 4.

In recent years, nanobubble technologies have drawn great attention due to their wide applications in many fields of science and technology. From previous studies, a kind of honeycomb structure for...

The thermal and hydraulic performance of a heat sink having aluminum honeycomb fins is numerically investigated by using a finite-volume-based solver. The fin height (H), the distance between the fins in the streamwise direction ( S y ) and the Reynolds number ( R e ) are selected as design parameters while the thermal resistance of the heat sink ( R t h ) and the pressure drop ( Δ P ) are regarded as the performance criteria. Each design parameter is examined in three levels and twenty-seven three-dimensional simulations are carried out in total. A computational domain consisting of three parts as the inlet and outlet sections and the test section where the honeycomb heat sink is located is used in the simulations. The CutCell mesh is employed for the test section while hexahedral meshes are used to discretize the inlet and outlet sections. The Reynolds-Averaged Navier-Stokes (RANS) based Realizable k-e turbulence model in combination with the enhanced wall function is employed in the simulations. The effects of each design parameter on the performance criteria are examined in detail.

The breath figure method, which is used to form porous films from water droplet templates, has attracted considerable interest because it is simple and applicable to a wide variety of materials. Research on breath figures took off after the 2000s, accompanied by new polymer synthesis methods, fabrication methods, and a wide variety of applications. There are several comprehensive reviews of the applications of the porous films, which are usually called ‘honeycomb films’ because their hexagonally packed porous structure resembles honeycombs. However, new materials, progress in preparation technologies for controlling nano- and microstructures, and large-area fabrication are still areas that require further research. Furthermore, new applications of honeycomb films have emerged. In this review, the recent development of honeycomb films prepared by the breath figure techniques and their numerous applications are summarized. The production of honeycomb films can be performed on an industrial scale, greatly broadening their possible applications in areas such as optics, photonics, surface science, biotechnology, and regenerative medicine. Present problems and future perspectives are also discussed.

We study topological states of honeycomb photonic crystals in absence of inversion symmetry using plane wave expansion and finite element methods. The breaking of inversion symmetry in honeycomb lattice leads to contrasting topological valley indices, i.e., the valley-dependent Chern numbers in momentum space. We find that the topological corner states appear for 60$^\circ$ degree corners, but absent for other corners, which can be understood as the sign flip of valley Chern number at the corner. Our results provide an experimentally feasible platform for exploring valley-dependent higher-order topology in photonic systems., 13 pages, 6 figures