The past few decades have witnessed growing research interest in developing powerful nanofabrication technologies for three-dimensional (3D) structures and devices to achieve nano-scale nano-precision manufacturing.

This paper presents a multi-Helmholtz unit series–parallel acoustic metamaterial with segmented noise control effect designed by taking advantage of the adjustable frequency band an metamaterial, aiming to change main spectrum characteristics under different driving conditions military equipment such as tanks. Based on transfer matrix method, theoretical model that can predict hybrid structure multiple Helmholtz resonator (HR) units is established, and its feasibility verified through finite...

For the common difficulties of noise control in a low frequency region, an adjustable parallel Helmholtz acoustic metamaterial (APH-AM) was developed to gain broad sound absorption band by introducing multiple resonant chambers enlarge bandwidth and tuning length rear cavity for each chamber. Based on coupling analysis double resonators, generation mechanism adjusting structural parameters analyzed, which provided foundation development APH-AM with tunable chambers. Different from other...

Rubber is widely applied in the field of electrical engineering due to its high elasticity. However, poor thermal conductivity can cause localized overheating and eventual failure. This issue be addressed through adding fillers with conductivity. In this study, natural rubber selected as matrix, while braided carbon fiber (B-CF), known for excellent conductivity, serves reinforcing phase. research defines cubic Bessel curves, establishes a curvilinear coordinate system, examines orthogonal...

The control of noise pollution in the low-frequency domain with various spectrum ranges requires development a novel tunable sound absorbing material, and multilayer stackable grouped acoustic metamaterial (MSG-AM) is proposed this research to obtain optimal reduction effect while minimizing occupied space. MSG-AM includes four layers eight Helmholtz resonators each layer divided into three groups, total 32 different are connected parallel. absorption property optimized by joint simulation...

As a newly developed ultrasmooth polishing technique, fluid jet (FJP) has been widely used for optical glass polishing. The size of the particle in slurry great influence on material removal rate and quality processed surface. mode affected by is investigated detail. Particle trajectories with different are calculated numerical simulations FJP process. Simulation results demonstrate that large will seriously deviate from streamline almost impact workpiece along straight line initial incident...

An acoustic metamaterial absorber of parallel–connection square Helmholtz resonators is proposed in this study, and its sound absorption coefficients are optimized to reduce the noise for given conditions factory. A two–dimensional equivalent simulation model built obtain initial value parameters a three–dimensional finite element constructed simulate performance cell, which aims improve research efficiency. The optimal cells obtained through particle swarm optimization algorithm,...

Acoustic metamaterials based on Helmholtz resonance have perfect sound absorption characteristics with the subwavelength size, but bandwidth is narrow, which limits practical applications for noise control broadband. On basis of Fabry-Perot principle, a novel absorber acoustic metamaterial by parallel connection multiple spiral chambers (abbreviated as MSC-AM) proposed and investigated in this research. Through theoretical modeling, finite element simulation, sample preparation experimental...

To achieve the broadband sound absorption at low frequencies within a limited space, an optimal design of joint simulation method incorporating finite element and cuckoo search algorithm was proposed. An acoustic metamaterial multiple parallel hexagonal Helmholtz resonators with sub-wavelength dimensions designed optimized in this research. First, initial geometric parameters investigated metamaterials were confirmed according to actual noise reduction requirements reduce optimization burden...

The composite rubber reinforced with hollow glass microsphere (HGM) was a promising material for noise reduction, and its sound insulation mechanism studied based on an acoustic finite element simulation to gain the appropriate parameter certain constraint conditions. built model included air domain, polymer domain inorganic particles domain. of investigated through distributions pressure level. influences parameters transmission loss (STL) were researched one by one, such as densities HGM,...

A plasma synthetic jet (PSJ) actuator (PSJA) with a Laval-shaped exit is investigated using numerical method alongside PSJA straight-shaped for comparison. The accuracy of the first verified by comparing simulation results experimental schlieren images and pressure measurement values. performance then in quiescent air. show that when dimensionless energy ε > 5.06, maximum velocity becomes supersonic higher than exit. opposite true ≤ 5.06. front PSJ much lower velocity, no obvious...

A Helmholtz resonator (HR) with an embedded aperture is effective acoustic metamaterial for noise reduction in the low-frequency range. Its sound absorption property significantly affected by shape. Sound properties of HRs various tangent sectional shapes were studied a two-dimensional finite element simulation. The sequence resonance frequency from low to high was olive, common trapeziform, reverse dumbbell and rectangle. Meanwhile, those cross-sectional investigated three-dimensional...

Large Eddy Simulation (LES) is first used to investigate the drag reduction effect of an array-based configuration Plasma Synthetic Jet Actuators (PSJAs) on a hemisphere in supersonic inflow, and analyze energy allocation array angle performance opposing (PSJ) this paper. Numerical simulation results have been compared with experimental data, confirming validity method. The show that different allocations significant hemisphere. However, change not as noticeable caused by allocation....

This study will examine the feasibility of applying hydrodynamic effect to ultrasmooth surface polishing. Differing from conventional pad polishing, polishing is noncontact, as wheel floated on workpiece under effect. The material removal mechanism and contour are analyzed in detail. Dynamic pressure shear stress distribution numerically simulated three dimensions different clearances between workpiece, showing that dynamic magnitude greatly influenced by clearance. It clearly demonstrated...

Experimental and numerical studies are carried out to validate the potential of opposing Plasma Synthetic Jet (PSJ) for drag reduction a hemisphere. Firstly, flow field changes PSJ analyzed by comparing experimental schlieren images simulation results in supersonic free stream Mach number 3. As is kind unsteady pulsed jet, shock standoff distance increases initially then decreases under control PSJ, which corresponds change strength PSJ. Accordingly, amount hemisphere decreases. It found...

Nanoparticle jet polishing (NJP) is presented as a posttreatment to remove magnetorheological finishing (MRF) marks. In the NJP process material removed by chemical impact reaction, and removal rate of convex part larger than that concave part. Smoothing thus can progress automatically in process. experiment, silica glass sample polished MRF was NJP. Experiment results showed marks were clearly. The uniform shows without destroying original surface figure. root-mean-square roughness improved...

A material removal mechanism of ceria particles with different sizes in a glass polishing process was investigated detail. Contrast experiments were carried out using slurries two kinds particle and amounts hydrogen peroxide (H 2 O ) added the slurries. The Ce 3+ ions on surface gradually oxidized to 4+ increased H concentration. It found that rate (MRR) decreased sharply an increasing concentration . There no when reached 2.0% for nanoparticle slurry. Nevertheless, application...