Numerical study of structural parameters influencing flow in a lunular valveless pump

2021 ◽  
Vol 92 (2) ◽  
pp. 025009
Author(s):  
Lipeng He ◽  
Zheng Zhang ◽  
Yongjun Miao ◽  
Da Zhao ◽  
Xiaoqiang Wu ◽  
...  
Keyword(s):  
Numerical Study ◽  
Structural Parameters ◽  
Valveless Pump

scholarly journals Numerical Study of an Ultra-Broadband All-Silicon Terahertz Absorber

2020 ◽  
Vol 10 (2) ◽  
pp. 436 ◽  
Author(s):  
Jinfeng Wang ◽  
Tingting Lang ◽  
Tingting Shen ◽  
Changyu Shen ◽  
Zhi Hong ◽  
...  
Keyword(s):  
Numerical Study ◽  
Structural Parameters ◽  
Impedance Matching ◽  
Single Layer ◽  
Transverse Magnetic ◽  
Absorption Efficiency ◽  
Absorption Mechanism ◽  
Loss Mechanism ◽  
Perfect Absorption ◽  
Terahertz Absorber

In this article we present and numerically investigate a broadband all-silicon terahertz (THz) absorber which consists of a single-layer periodic array of a diamond metamaterial layer placed on a silicon substrate. We simulated the absorption spectra of the absorber under different structural parameters using the commercial software Lumerical FDTD solutions, and analyzed the absorption mechanism from the distribution of the electromagnetic fields. Finally, the absorption for both transverse electric (TE) and transverse magnetic (TM) polarizations under different incident angles from 0 to 70° were investigated. Herein, electric and magnetic resonances are proposed that result in perfect broadband absorption. When the absorber meets the impedance matching principle in accordance with the loss mechanism, it can achieve a nearly perfect absorption response. The diamond absorber exhibits an absorption of ~100% at 1 THz and achieves an absorption efficiency >90% within a bandwidth of 1.3 THz. In addition, owing to the highly structural symmetry, the absorber has a polarization-independent characteristic. Compared with previous metal–dielectric–metal sandwiched absorbers, the all-silicon metamaterial absorbers can avoid the disadvantages of high ohmic losses, low melting points, and high thermal conductivity of the metal, which ensure a promising future for optical applications, including sensors, modulators, and photoelectric detection devices.

scholarly journals Experimental and numerical study of helical auxetic yarns

2020 ◽  
pp. 004051752097719
Author(s):  
Yajie Gao ◽  
Xiaogang Chen ◽  
Rachel Studd
Keyword(s):  
Numerical Study ◽  
Structural Parameters ◽  
Tensile Modulus ◽  
Diameter Ratio ◽  
Element Analysis ◽  
Yarn Quality ◽  
Numerical Studies ◽  
Helical Angle ◽  
Potential Applications ◽  
New Finding

Auxetic materials, including textiles, exhibit a negative Poisson’s ratio (NPR), which is of interest for many applications. This research aims to optimize the structural parameters of helical auxetic yarns (HAYs) and to evaluate the auxetic performance of these yarns. The research reports on the improvement of auxetic yarn quality and the yarn auxeticity through studying the effect of helical angles, diameter ratio and tensile moduli of the two plies, as well as the binder filament feeding. The maximum NPR of the optimized auxetic yarns was experimentally achieved as low as –9.6, with the helical angle of around 14.0° on average using the optimal machine setting. The optimized yarn parameters enabled the making of high-quality auxetic yarns with a wider range of machine settings than before. In parallel, theoretical and numerical studies were carried out for the engineering design of auxetic yarns, which enabled comparisons among the experimental results, calculated results and results from finite element analysis. The comparison showed that a lower initial helical angle, higher tensile modulus of the wrap ply and lower tensile modulus of the core ply led to a higher auxetic effect. A new finding is reported in that a concave relationship between the diameter ratio and the NPR was discovered. The results of this study could assist researchers in producing HAYs, and this type of HAY could be used for many potential applications, such as filtration and impact protection.

Theoretical and numerical study of nonlinear acoustic absorbers for low frequency noise control

2021 ◽  
Vol 263 (1) ◽  
pp. 5600-5604
Author(s):  
Min Yang ◽  
Xianhui Li ◽  
Zenong Cai ◽  
Junjuan Zhao ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Averaging Method ◽  
Numerical Study ◽  
Structural Parameters ◽  
Low Frequency ◽  
Frequency Noise ◽  
Flow Equations ◽  
State Response ◽  
Runge Kutta Method ◽  
Absorption Performance

In this paper, the sound absorption characteristics of cubic nonlinear sound-absorbing structures are analyzed by theoretical and numerical methods. The slow flow equations of the system are derived by using complexification averaging method, and the nonlinear equations which describe the steady- state response are obtained. The resulting equations are verified by comparing the results which respectively obtained from complexification-averaging method and Runge-Kutta method. It is helpful to optimize the structural parameters and further improve the sound absorption performance to study the variation of the sound absorption performance of cubic nonlinear structure with its structural parameters.

scholarly journals Impact between buildings during earthquakes

1994 ◽  
Vol 27 (2) ◽  
pp. 107-113
Author(s):  
A. J. Carr ◽  
P. J. Moss
Keyword(s):  
Dynamic Analysis ◽  
Numerical Study ◽  
Structural Parameters ◽  
Seismic Excitation ◽  
Relative Importance ◽  
Two Dimensional ◽  
Analysis Program ◽  
Framed Structures ◽  
Design Values ◽  
The Impact

A numerical study of the parameters affecting the impact between adjacent buildings subjected to seismic excitation has been carried out in an endeavour to quantify the relative importance of the structural parameters. A two-dimensional inelastic dynamic analysis program was used to model various combinations of adjacent framed structures subjected to ground accelerograms and where the frames are assumed to be separated by distances sufficiently small as to permit contact. Collisions were modelled using special contact elements which will transmit forces when the specified gap has been closed. It will be shown that where there are adjoining frames are of different heights, large increases in response are observed in the upper part of the taller frame. Pounding can also amplify the effects of localised changes in stiffness and strength up the frame-, producing member demands greatly in excess of the normal design values.

Numerical Study of Deformation and Fracture of Ceramics Nanocomposite with Different Structural Parameters under Mechanical Loading

2016 ◽  
Vol 683 ◽  
pp. 601-608
Author(s):  
Igor S. Konovalenko ◽  
Egor M. Vodopjyanov ◽  
Evgenii V. Shilko
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Numerical Study ◽  
Structural Parameters ◽  
Phenomenological Approach ◽  
Sample Volume ◽  
Model Composite ◽  
Deformation And Fracture ◽  
Kinetics Of ◽  
Geometrical Dimensions

Deformation, fracture and effective mechanical properties of sintered ceramics composite under uniaxial compression were studied. To perform this investigation the plain numerical model of ceramics composites based on oxides of zirconium and aluminum with different structural parameters was developed. The model construction was carried out within the frame of particle based method, namely the movable cellular automaton method (MCA). The implementation of the phase transition in the MCA-model composite was carried out on the basis of the phenomenological approach, the main point of which was the formulation of the principle of irreversible mechanical behavior of the material. Increase the fracture toughness of ceramics after (T-M) transition in its structure was realized in the model by introducing transition kinetics of the automata pair from "bound" to an "unbound" state. The structure of model composite was generated on the basis of scanning electron microscope images of micro-sections of real composite. The influence of such structural parameters as geometrical dimensions of layers, inclusions, and their spatial distribution in the sample, volume content of the composite components and their mechanical properties, as well as the amount of zirconium dioxide undergone the phase transformation on the mechanical response were investigated

Characterization of bimodal facies distributions using effective anisotropic complex resistivity: A 2D numerical study based on Cole-Cole models

Geophysics ◽  
2009 ◽  
Vol 74 (3) ◽  
pp. A19-A22 ◽  
Author(s):  
Tobias Winchen ◽  
Andreas Kemna ◽  
Harry Vereecken ◽  
Johan A. Huisman
Keyword(s):  
Electrical Properties ◽  
Numerical Study ◽  
Structural Parameters ◽  
Electrical Impedance Spectroscopy ◽  
Model Parameters ◽  
Complex Resistivity ◽  
Correlation Lengths ◽  
Mixing Parameter ◽  
Cole Model

Subsurface heterogeneity characteristics are of major importance in hydrologic modeling, and likely result in anisotropic electrical properties. We computed the anisotropic effective complex resistivity of 2D bimodal facies distributions numerically. Complex resistivities of individual facies are described in terms of the Cole-Cole relaxation model. First, we determined that effective DC resistivities of the distributions can be reasonably well described by power averaging the properties of individual facies. We found a clear relationship between the mixing parameter and correlation lengths of the facies distributions with respect to horizontal and vertical directions. Then, we used the power-law mixing model to invert for individual Cole-Cole model parameters by fitting predicted electrical responses to simulated spectral effective complex-resistivity data for the two perpendicular directions. Thus, it is possible to derive the electrical properties of individual facies as well as structural parameters describing bimodal facies distribution by means of a noninvasive measurement approach. In particular, anisotropy of the spectral complex-resistivity response provides information on correlation lengths of the distribution. This finding is relevant for all applications of electrical-impedance spectroscopy where anisotropy might be encountered.

Effect of process and nozzle structural parameters on the wrapping quality of core-spun yarns produced on a modified vortex spinning system

2021 ◽  
pp. 004051752198909
Author(s):  
Zeguang Pei ◽  
Xingbao Wang ◽  
Zhimin Li ◽  
Lei Xiao ◽  
Tao Bai ◽  
...  
Keyword(s):  
Vortex Core ◽  
Numerical Study ◽  
Vision System ◽  
Structural Parameters ◽  
Feeding Tube ◽  
Spun Yarn ◽  
Nozzle Pressure ◽  
Spun Yarns ◽  
Nozzle Inlet

Vortex core-spun yarn containing a metal wire has a broad application prospect owing to the combination of its fasciated structure, durability, comfort, and its electrical properties. In this paper, three-dimensional numerical simulations on the flow characteristics inside the nozzle of a modified vortex spinning system for producing core-spun yarns are carried out to investigate the effect of some process and nozzle structural parameters—the nozzle pressure, distance between nozzle inlet and spindle, and protrusion length of the filament feeding tube—on the flow field. Using a machine vision system, experiments are also conducted to investigate the effects of these parameters on the wrapping defects of the vortex core-spun yarns which are then analyzed based on the simulation results. The number of wrapping defects on the yarn greatly decreases as the nozzle pressure increases from 4 × 105 Pa to 5 × 105 Pa. As the distance between nozzle inlet and spindle increases, the number of wrapping defects on the yarn first decreases and then increases. The effect of protrusion length of the filament feeding tube is found to be insignificant. This experimental and numerical study can provide a feasible way for optimizing the quality of the core-spun yarn produced on the modified vortex spinning system and analyzing the mechanism of the effects of parameters.

scholarly journals Numerical Study of a Wide-angle Near-Perfect Absorber for the Visible Regime Incorporating Metal-Dielectric-Metal Subwavelength Grating Structure

2022 ◽  
Author(s):  
Wenlong Zou ◽  
Heng Zhang ◽  
Yun Zhou
Keyword(s):  
High Performance ◽  
Numerical Study ◽  
Incidence Angle ◽  
Structural Parameters ◽  
Visible Region ◽  
Normal Incidence ◽  
Refractory Metals ◽  
Perfect Absorber ◽  
Subwavelength Grating ◽  
Grating Structure

Abstract A near-perfect absorber for the visible regime based on metal-dielectric-metal subwavelength grating structure with the refractory metals is designed and demonstrated numerically. The absorber presents an average absorption over 98.4% in the visible regime at normal incidence. Angle-relative analysis shows that the proposed structure has good angle-tolerance. The high average absorption (86.6%) in the visible region can be maintained with the incident angles up to 60°. Through the analysis of the magnetic field, the physical origin is verified that this excellent absorption performance mainly stems from the cooperative effect of surface plasmonic resonances and the intrinsic broadband spectral responses by the refractory metals. In addition, the dependence of the absorption spectrum of the proposed absorber on the structural parameters is analyzed. This work provides an idea for the design of high-performance absorbers and has potential applications in advanced light energy capture and integration systems.

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