Triangular Lattice Configuration Research Articles

Generalizing the probability of reaching a destination in case of route blockage

When road blockages occur owing to disasters or congestion, traffic is unable to pass, paralyzing urban functions. Though previous studies have analyzed road blockages in specific cities, a more general approach valid for a wide range of road networks is required. In this study, different blockage rates were applied to three square lattice sizes as well as square, triangular, and hexagonal lattice configurations to simulate an assortment of road network geometries, and agent-based modeling was applied to quantitatively evaluate the resulting arrival probabilities and travel times. The results did not change significantly with the blockage rate, regardless of lattice size. For the square lattice, the route from the starting point to the destination point was secured when the blockage rate was ≤30%, but the probability of not arriving at the destination point increased considerably when the blockage rate was >30% and reached an infinitesimally small value when the blockage rate was >60%. When fewer routes connected the lattice intersections, the destination was more likely to be unreachable, even for a low blockage rate. These results were then validated by percolation theory, demonstrating an effective basis for travel feasibility evaluations when an urban road network is blocked.

Experiment Study of Heat Transfer to Supercritical Water in a Triangular-Lattice Configuration

The experimental research of heat transfer to supercritical water in a triangular-lattice configuration has been performed on the supercritical water multipurpose test loop. Circumferential non-uniformed wall temperature distribution and heat transfer enhancement induced by the grids were observed in the bundles. The heat transfer data under conditions of different heat flux, mass flux and pressure were obtained. Finally, an empirical correlation with the prediction deviation of ±15% was developed to predict the supercritical heat transfer behaviors in the triangular-lattice.

Vortex lattice formation in dipolar Bose-Einstein condensates via rotation of the polarization

The behaviour of a harmonically trapped dipolar Bose-Einstein condensate with its dipole moments rotating at angular frequencies lower than the transverse harmonic trapping frequency is explored in the co-rotating frame. We obtain semi-analytical solutions for the stationary states in the Thomas-Fermi limit of the corresponding dipolar Gross-Pitaevskii equation and utilise linear stability analysis to elucidate a phase diagram for the dynamical stability of these stationary solutions with respect to collective modes. These results are verified via direct numerical simulations of the dipolar Gross-Pitaevskii equation, which demonstrate that dynamical instabilities of the co-rotating stationary solutions lead to the seeding of vortices that eventually relax into a triangular lattice configuration. Our results illustrate that rotation of the dipole polarization represents a new route to vortex formation in dipolar Bose-Einstein condensates.

Polarizing properties of a 2D photonic crystal slab for simultaneous in-plane and out-of-plane light incidence

We study a 2D photonic crystal slab for its properties of polarizing light propagating in the plane of periodicity and for light incident from outside the plane of the slab as well. We identify the frequency ranges that can yield polarized light for both cases. The analysis is done for triangular and square lattice configurations in both symmetric and asymmetric background media. The 2D photonic crystal slab can behave as both reflection-type and transmission-type polarizer for in-plane and out-of-plane incidence of light. The structure in an asymmetric background, which is more favorable for practical applications, yields orthogonally polarized out-of-plane transmitted states which ultimately radiate to the cladding medium within certain frequency interval of the incident light.

3D printed hierarchical honeycombs with shape integrity under large compressive deformations

We describe the in-plane compressive performance of a new type of hierarchical cellular structure created by replacing cell walls in regular honeycombs with triangular lattice configurations. The fabrication of this relatively complex material architecture with size features spanning from micrometer to centimeter is facilitated by the availability of commercial 3D printers. We apply to these hierarchical honeycombs a thermal treatment that facilitates the shape preservation and structural integrity of the structures under large compressive loading. The proposed hierarchical honeycombs exhibit a progressive failure mode, along with improved stiffness and energy absorption under uniaxial compression. High energy dissipation and shape integrity at large imposed strains (up to 60%) have also been observed in these hierarchical honeycombs under cyclic loading. Experimental and numerical studies suggest that these anomalous mechanical behaviors are attributed to the introduction of a structural hierarchy, intrinsically controlled by the cell wall slenderness of the triangular lattice and by the shape memory effect induced by the thermal and mechanical compressive treatment.

Tuning photonic bands in plasma metallic photonic crystals

Introducing plasma in the background provides additional degrees of freedom for tuning dispersion curves of photonic crystals. 2D photonic crystals in triangular lattice arrangements offer more global bandgap regions and thus are of more interest for various applications. The dispersion characteristics of a two-dimensional plasma metallic photonic crystal (PMPC) in square as well as triangular lattice arrangements have been analyzed in this paper using the orthogonal finite difference time domain method. The dispersion characteristics of PMPCs for the range of r/a ratios and plasma frequencies for triangular lattice configuration have been analyzed. On introducing plasma in the background, the photonic bands of PMPC are shifted towards higher normalized frequencies. This shift is more for lower bands and increases with plasma frequency. The cut-off frequency was observed for both TE and TM polarizations in PMPC and showed strong dependence on r/a ratio as well as plasma frequency. Photonic bandgaps of PMPC may be tuned by controlling plasma parameters, giving opportunity for utilizing these PMPC structures for various applications such as fine-tuning cavities for enhanced light-matter interaction, plasmonic waveguides, and Gyrotron cavities.

Design of radial sonic crystal for sound attenuation from divergent sound source

Sonic crystals are periodic arrangement of sound hard scatterers, generally in square or triangular lattice configuration. The periodic obstruction to the sound wave by the scatterers leads to an interesting phenomenon of the band gap, which results in a high sound attenuation in the band gap region. In this work, a design of sonic crystal called as the radial sonic crystal is presented, which consists of periodic structures in polar coordinates. Such a structure attenuates divergent sound source. The radial sonic crystal is designed based on the Webster horn equation and using the property of invariance of governing equation from one unit cell to another. The designed radial sonic crystal is tested experimentally and by the finite element simulation. The experimental results are in good agreement with the simulation and show high sound attenuation of 30 dB. The high sound attenuation is due to the presence of the band gap in the radial sonic crystal.

Tuning Magnetic Properties of α-MnO2 Nanotubes by K+ Doping

α-KxMnO2 nanotubes with x = 0.10, 0.12, 0.15, and 0.17 have been synthesized through acid and alkali treatments of the precursor α-MnO2 nanotubes. For the samples with x = 0.10 and 0.12, a large divergence of the ZFC and FC susceptibilities and pronounced hysteresis at low temperature are observed. However, the samples with x = 0.15 and 0.17 are antiferromagnetic with Neel temperatures of 25.4 and 25.3 K, respectively. The reciprocal susceptibility and electrical conductivity indicate that the samples with x = 0.15 and 0.17 undergo a charge separation transition from mixed/averaged valence state manganese ions to Mn3+ and Mn4+ between 250 and 300 K. Below half occupancy of the K+ site (x ≤ 0.125), the strong geometrical frustration due to the triangular lattice configuration and the mixture of Mn3+/Mn4+ result in the spin-glass behavior of the samples with x = 0.10 and 0.12. Above half occupancy of the K+ site, the samples with x = 0.15 and 0.17 exhibit an antiferromagnetic feature due to the charge separ...

Dispersion-flattened polarization-maintaining photonic crystal fiber for nonlinear applications

In this paper, we propose a novel photonic crystal fiber design to achieve high birefringence, high nonlinearity with a flattened dispersion profile. The air holes which are embedded in silica are arranged in triangular lattice configuration. In the core region, an air hole is introduced as the central defect to flatten the dispersion curve. The shape of the defect air hole is deliberately designed elliptical so that high birefringence in the PCF is obtained for polarization-maintaining purpose. The structural parameters are carefully selected to optimize the optical properties.

Frequency-controlled wave focusing by a sonic crystal lens

In this study, the frequency dependence of the focalization point was investigated for a sonic crystal lens with a triangular lattice configuration. Theoretical and experimental study results showed that focalization point location of the sonic crystal lens with a triangular lattice configuration depended on the frequency of the wave source in the second frequency band. This property of the sonic crystal lens enables shifting of the focalization point location by means of the frequency of a single acoustic source, and it can find application in technologies based on acoustic wave focusing.

Magnetism and cluster glass dynamics in geometrically frustrated LuFe2O4

We report on the magnetic properties of high quality LuFe2O4 single crystals grown by the floating zone method. dc and ac susceptibility measurements and analysis reveal a ferrimagnetic transition at ∼240 K followed by a re-entrant cluster glass transition below 225 K, with an additional magnetic transition around 170 K. Strong frequency dependence of the real (χ′) and imaginary (χ″) parts of the ac susceptibility observed at both these temperatures indicate glassy behavior and we quantitatively fit the data to a cluster glass model, τ=τo(Tf/Tg−1)−zv. Our studies show that these multiple transitions are consistent with the picture of ferrimagnetic clusters in the iron oxide planes with triangular lattice configuration favoring spin frustration and glass dynamics.

Fabrication and characterization of three-dimensionalTa2O5/SiO2 photonic crystals

Three-dimensional (3D) Ta2O5/SiO2 photonic crystals in the visible-violet spectral region are fabricated by an auto-cloning techniqueon patterned substrates with triangular lattice configurations and their in-plane (the stackXY plane) optical properties are studied. Reflection measurements by normal incidence of lighton to the cleaved facet of the photonic crystal reveal maximum reflections at certainphoton energies. Comparison with calculated band structure demonstrates that thereflection peaks are either due to the photonic bandgap (PBG) within which the lightpropagation is forbidden, or due to heavy photons associated with flat bands. A two-stepdeposition method is adopted to insert luminescent rhodamine 590 into the photoniccrystal and the emission property is strongly modified by the photonic crystal. Possibleapplications of such 3D photonic crystals in optical components are discussed.

Design of Elliptic Gabor Wavelets with Triangular Lattice Configuration and their Application to Target Detection

This paper introduces elliptic Gabor wavelets with the triangular lattice configuration as a model-based target recognition approach. And, making the degree of overlap uniform between the neighboring Gabor wavelets in the frequency domain, it enables to cover the frequency space with higher density than the existing circular Gabor wavelets with square lattice configuration. Thus, it succeeds efficiently to extract a rotation and scale invariant features of the target objects. This paper, furthermore, presents some useful guidelines for designing system parameter values by a large amount of experiments, and shows effectiveness of the proposed method by comparing it with other methods.

2D Lattices on Substrates with Randomly Distributed Pinning Centers: A Possible Scaling Law for Domain Sizes

ABSTRACTWe consider 2D lattices which are disordered by an external field, in this case by a dense, random distribution of attractive pinning centers of an underlying substrate. The preferred configuration of the 2D system with screened-Coulomb two-body interactions and a fixed number of particles is a triangular lattice configuration. The pinning centers strongly affect the triangular lattice configuration. By keeping the location and the density of the pinning centers fixed, we study the effects of pinning strength on the structural properties of the lattice. We find that the strongly disordered lattice prefers to form irregular domains of size s which are composed entirely of topological defects. The distribution of sizes of these domains, D(s) suggest that s−τ for sufficiently large s. Our results are consistent with τ ≥ 2 in the solid phase and τ < 2 in the liquid phase. We present a general argument in support of our findings and suggest that the physics which dictates the structure of 2D lattices on substrates with randomly distributed pinning centers is the same as that for a broad range of problems in which an external field strongly influences the behavior of an interacting physical system.

Explaining reversal in half a population of magnetic dipoles

At a critical magnetic field certain dipole arrays surprisingly switch from full to half-alignment. The result is explicable by mutual inductance calculations for expanding current-loopdipoles. A known triangular lattice configuration becomes energetically unfavourable as its loops expand and nearly touch. Mutual inductance plunges negatively as opposed current-elements near the touching point.

Magnetic bubble domain interactions

We consider the interaction between cylindrical magnetic (“bubble”) domains and predict a stable triangular lattice configuration in an applied field H c 1 < H 0 < H c 2. For O < H 0 < H c 1 a stripe pattern is stable. Detailed predictions agree very well with experiment.