This study investigates the properties of band gaps circular core filling fractal phononic crystals (CCFFPCs), specifically focusing on impact different positions frequency gaps. The research demonstrates that at central significantly influences formation and widening low-frequency gaps, while corner edges predominantly affects mid-frequency edge centers effectively opens broadens high-frequency These results reveal relationship between gap tuning, providing a theoretical foundation for...

Abstract In this study, band gaps of SH-waves (horizontally polarized shear waves) propagating in a thermal-sensitive viscoelastic matrix are investigated. Metallic films acting as heat sources periodically embedded into the matrix, which establishes inhomogeneous thermal field. The homogenous is therefore transformed functionally gradient phononic crystals (PCs). A three-parameter solid model employed to describe viscoelasticity present matrix. By virtue transfer method incorporated within...

Elastic wave metamaterials, such as phononic crystals (PnCs) always composed of several materials in terms periodical structures, possess unique acoustic characteristic which can exhibit outstanding performance forbidding propagation with some specific frequencies. In this paper, due to the thermal sensitivity thermally induced shape memory polymers (SMP) and period fields, a tunable planar metamaterial is constituent homogeneous proposed designed realize function waveguides. A thin plate...

Hexagonal honeycombs form the common core of composite sandwich structures. In this study, on basis hexagonal honeycomb model, a second-order is established by cutting pores cell wall to realize secondary lightweight design. Furthermore, in-plane and out-of-plane dynamic crushing behaviors are investigated combining theoretical analysis with numerical simulation. The effect variation in pore sizes deformation modes, mechanical properties, energy absorption capacities under different impact...

As a useful index, i.e. the Richardson number Ri, is modified in non-uniform saturated moist flow, based on fact that liquid water partially dropped out parcel air. This more realistic real atmosphere, especially rainfall process. The Ri presents adequately influence of numerator, Brunt–Vaisala frequency (BVF), instability. Compared to several former formulae generalized by Durran and Klemp, evidently decreases stability rainy regions. In theory, BVF fix discontinuity latent heat release...

针对传统球面面形干涉测量中手动调整被测件姿态精度低、速度慢的问题,提出了激光共焦干涉面形快速高精度自动测量方法。该方法通过共焦精密定焦技术实现了对被测件共焦位置的高精度轴向定位;通过五维自动调整架对被测件进行姿态调整,实现了被测件的高精度横向定位;通过Zernike拟合对被测件进行精调以减小离焦误差和倾斜误差,实现了对干涉面形的零条纹调整。最终实现了激光共焦干涉面形自动测量。构建了激光共焦干涉面形测量系统,实验表明:该方法的面形测量结果与Zygo干涉仪的测量结果相差0.000 6<italic>λ</italic>,重复测量精度可达0.001 9<italic>λ</italic>,平均单次干涉面形测量时间为16.5 s,与手动调整至零条纹相比测量效率提高了1.56倍。该方法为干涉面形的快速高精度测量提供了一种有效的手段。

In the thesis, we investigate a two-dimensional period slab composite structure composed of steel/epoxy and adhered with series heat films. Various types periodic thermal fields are introduced into by loading diverse powers on Leveraging sensitivity epoxy, these facilitate changes tuning in band structures slab. Therefore, thermal–mechanical coupling model based finite element method via commercial software is established to obtain dispersion curves transmission spectrums structure. The...

This study presents a tunable phononic crystal (PnC) composed of liquid–solid components, demonstrating adjustable waveguiding and directional transmission capabilities through the rotation embedded scatterers. A two-dimensional model featuring grooved steel rods in water is analyzed using finite element simulations to evaluate band structures spectra. To achieve widest full gap, genetic algorithm integrated optimize structural parameters. By examining supercell with central defect, wave...

A proper lattice structure consisting of homogeneous material is designed in this paper to investigate the maximum bandwidth perfect structures and tunable property waveguide with linear geometric defect by means selecting optimal cell. simulation model based on finite element method used calculate dispersion curves transmission spectrums different parameters. Meanwhile, a simplified theoretical unit cell, which considers mass grid bar stiffness node area, applied validate accuracy result...

This study aims to quantify the response of a westerly-trough rainfall episode that occurred in summer 2020 multi-scale topographic control southwestern China, based on observations and numerical simulations. The topography is composed Tibetan Plateau, Hengduan Cordillera (HC), Sichuan Basin (SB). westerly trough was characterized by southeastward deepening together with an in-phase propagating episode. By utilizing results experiments, how impacted this explored. It found HC pivotal factor...

Spectral analysis of terrain height variance is conducive to quantitatively study the characteristics and grid-size selection for mesoscale models. Improved topographic resolutions can lead variations appropriate grid size a fixed analyzed area. methods one-dimensional weighted average arithmetic mean were used investigate specific impact on distribution spectra models landslide-prone areas in western Sichuan. The results indicate that maximum spectral energy (the series) 30″ resolution (R1)...

The electronic structure and optical properties of the perovskite oxide LaAlO 3 , SrTiO /SrTiO interfaces were studied by density functional theory (DFT) based on First-principles plane wave pseudopotential method.The energy band analysis shows that (AlO 2 ) -/(TiO 0 interface is insulating with gap being 1.888 eV, whereas (LaO) + /(SrO) seems to be a semiconductor or semimetal 0.021 eV.Moreover, we have also investigated interfaces, results indicate intensities absorption, reflectivity,...

As a kind of new intelligent materials, liquid crystal elastomer (LCE) has attracted widespread interest. In this paper, we introduce LCE into chiral phononic (CPC), and investigate the properties band structures based on iterative calculation method. The effects dextral bending angle, geometric parameters [Formula: see text] text], director rotation angle bandgaps are mainly discussed. This work is meaningful try for application in acoustic field propose strategy designing PC with tunable bandgaps.

Elastic wave metamaterials, such as phononic crystals (PnCs) always composed of several materials in terms periodical structures, possess unique acoustic characteristic which can exhibit outstanding performance forbidding propagation with some specific frequencies. In the present paper, due to thermal sensitivity thermally induced shape memory polymers (SMP) and period fields, a tunable planar metamaterial is constituent homogeneous proposed designed realize function waveguides. A thin plate...