scholarly journals Miniaturized Spiral Metamaterial Array for a Ventilated Broadband Acoustic Absorber

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Xingxing Liu ◽  
Xiang Li ◽  
Zhiying Ren
Keyword(s):  
Acoustic Waves ◽  
High Efficiency ◽  
Metamaterial Structure ◽  
Small Space ◽  
Archimedean Spiral ◽  
Broadband Absorber ◽  
Acoustic Reduction ◽  
Different Types ◽  
Metamaterial Absorbers ◽  
Ventilation Performance

The high-efficiency and broadband acoustic reduction performance in a miniaturized free-flow structure remains challenging in acoustic engineering applications due to the contradiction of ventilation and acoustic reduction performance. Traditional acoustic absorbers can sufficiently attenuate acoustic wave, but meanwhile, block fluid flow due to the longitudinal nature of acoustic waves that can transmit among any small holes. Although different types of ventilated metamaterial absorbers (VMAs) with proper reduction and ventilation performance have been demonstrated recently, their insufficiencies lie in small open-area ratios, not efficient-enough reduction performance, bulky structure, and narrow working band. To further solve existing defects, a ventilated broadband absorber with the miniaturized metamaterial structure has been proposed. The designed absorber consists of miniaturized Archimedean spiral units, which can be easily stacked to achieve broadband and ventilated performance. This work opens up possibilities for practical acoustic applications where both noise control and ventilation are required, especially in a small space.

Mechanisms and applications of terahertz metamaterial sensing: a review

Nanoscale ◽  
2017 ◽  
Vol 9 (37) ◽  
pp. 13864-13878 ◽  
Author(s):  
Wendao Xu ◽  
Lijuan Xie ◽  
Yibin Ying
Keyword(s):  
Different Types ◽  
Thz Sensing ◽  
Metamaterial Absorbers ◽  
Metallic Meshes

THz sensing using different types of metamaterials, including metasurfaces, metamaterial absorbers, metallic meshes and guided spoof plasmon structures.

The thrust measurement system research for combined nozzle in small space

2018 ◽  
Vol 41 (4) ◽  
pp. 1149-1159
Author(s):  
Yonghua Lu ◽  
Jing Li ◽  
Xiang Zhang ◽  
Yang Li
Keyword(s):  
Measurement System ◽  
Force Sensor ◽  
Test Method ◽  
Small Space ◽  
System A ◽  
Calibration Experiment ◽  
Different Types ◽  
Thrust Measurement ◽  
Nozzle Thrust ◽  
Thrust Forces

For measuring the thrust of combined nozzles in satellite thruster with a small space, the test method that the nozzle directly sprays on the load baffle is employed in this paper. The key problem is how to design the positions of 10 load baffles and how to construct the measurement system. A set of complete and automatic nozzle thrust measurement system is designed and built, and the influence of the load baffle applied on the flow field of nozzles is analyzed using the software FLUENT. Furthermore, the load surface locations of the sensors for the different types of nozzles are analyzed. We draw the conclusion that the load baffle position should range from 4–8 mm for the I-type nozzle and range in 6–12 mm for II-type and III-type nozzle. The correction coefficients of the thrust forces for all channels of the measurement system are determined in the calibration experiment. The uncertainty of measurement system is estimated and the error source of the measurement system is traced. We found that the systematic uncertainty is mainly contributed by the A-type uncertainty which is related with the nozzle dimension and its inner structure. The B-type uncertainty of system is contributed by the force sensor.

scholarly journals Analysis of Related Technologies Used in Fuel Cell Vehicles

2021 ◽  
Vol 2125 (1) ◽  
pp. 012011
Author(s):  
Ziyi Du ◽  
Hongxu Zhan
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Automotive Industry ◽  
High Efficiency ◽  
Management Strategies ◽  
Production Model ◽  
Hydrogen Energy ◽  
Fuel Cell Vehicles ◽  
Energy Applications ◽  
Different Types

Abstract Nowadays, many types of fuel cells have made significant progress. In 2014, they were applied to the production model Toyota’s FCHV-Adv. With their high efficiency and low pollution, fuel cells have gradually started to replace some traditional technologies in many energy applications and production industries and have become a hot topic of interest in recent years. Depending on the type of fuel, there are various types, and different fuel cells work on different principles, leading to differences in their performance. This paper lists the different fuel cells and their application scenarios in the automotive industry. In addition, the use of hydrogen in fuel cell vehicles is also a major concern. This paper briefly discusses the current hydrogen production and four different types of fuel cell vehicles and their energy management strategies. All the technical advantages of fuel cells and hydrogen energy are ultimately reflected in fuel cell vehicles, and this paper describes the current challenges and future possibilities.

scholarly journals Magnetic Micromachine Using Nickel Nanoparticles for Propelling and Releasing in Indirect Assembly of Cell-Laden Micromodules

Micromachines ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 370 ◽  
Author(s):  
Jianing Li ◽  
Huaping Wang ◽  
Juan Cui ◽  
Qing Shi ◽  
Zhiqiang Zheng ◽  
...  
Keyword(s):  
Nickel Nanoparticles ◽  
High Efficiency ◽  
Three Dimensional ◽  
Electromagnetic System ◽  
Bioactive Materials ◽  
Magnetic Assembly ◽  
Different Types ◽  
End Effectors ◽  
Set Up ◽  
High Flexibility

Magnetic micromachines as wireless end-effectors have been widely applied for drug discovery and regenerative medicine. Yet, the magnetic assembly of arbitrarily shaped cellular microstructures with high efficiency and flexibility still remains a big challenge. Here, a novel clamp-shape micromachine using magnetic nanoparticles was developed for the indirect untethered bioassembly. With a multi-layer template, the nickel nanoparticles were mixed with polydimethylsiloxane (PDMS) for mold replication of the micromachine with a high-resolution and permeability. To actuate the micromachine with a high flexibility and large scalable operation range, a multi-pole electromagnetic system was set up to generate a three-dimensional magnetic field in a large workspace. Through designing a series of flexible translations and rotations with a velocity of 15mm/s and 3 Hz, the micromachine realized the propel-and-throw strategy to overcome the inevitable adhesion during bioassembly. The hydrogel microstructures loaded with different types of cells or the bioactive materials were effectively assembled into microtissues with reconfigurable shape and composition. The results indicate that indirect magnetic manipulation can perform an efficient and versatile bioassembly of cellular micromodules, which is promising for drug trials and modular tissue engineering.

scholarly journals Damage analysis of a perfect broadband absorber by a femtosecond laser

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ahasanul Haque ◽  
Monir Morshed ◽  
Ziyuan Li ◽  
Li Li ◽  
Kaushal Vora ◽  
...  
Keyword(s):  
Optical Properties ◽  
Solar Cells ◽  
Femtosecond Laser ◽  
Metamaterial Absorber ◽  
Damage Analysis ◽  
Broadband Absorber ◽  
Absorption Bandwidth ◽  
Refractory Ceramic ◽  
Tungsten Boride ◽  
Metamaterial Absorbers

Abstract Plasmonic metamaterial absorbers are particularly important in different applications such as photodetectors, microbolometers and solar cells. In this paper, we propose a tungsten boride (WB, a refractory ceramic) based broadband metamaterial absorber whose optical properties is numerically analyzed and experimentally characterized. We have also analyzed the damage characteristics of this absorber using a femtosecond laser and compared with an ordinary Au metamaterial absorber. We observe that WB has almost the double absorption bandwidth with absorption more than 90% over the spectral range of 950 to 1400 nm when compared with the Au counterpart. Furthermore, we show that Au metamaterial is damaged at the power of around 36.4 mW whereas WB metamaterial is not damaged at that power (WB has high Tammann temperature than Au)-however the atom of WB material was knocked off by the bombardment of a femtosecond laser.

The Study on Experiments of Oilfield Wastewater Treatment by Microwave-Assisted Demulsification

2012 ◽  
Vol 599 ◽  
pp. 516-520 ◽  
Author(s):  
Hong Mei Cui ◽  
Ling Fei Ke ◽  
Han Bing Qi ◽  
Li Yun Chen
Keyword(s):  
High Efficiency ◽  
Microwave Treatment ◽  
Bactericidal Effect ◽  
Oil Field ◽  
Oily Wastewater ◽  
Small Space ◽  
Microwave Technology ◽  
Microwave Assisted ◽  
Leading Role ◽  
Discharge Water

Oily wastewater from oil field by microwave induced and catalytic demulsification was studied in this paper. The advantages and prospects of the microwave technology was analyzed. Microwave treatment of oilfield wastewater has advantages such as equipment occupies a small space, easy to operate, portable, easy to transport, easy to installation and commissioning, short reaction time, high efficiency, discharge water which has good quality, temperature and other factors do not affect the treatment oilfield wastewater effect and so on. Microwave also has a bactericidal effect which was applicable to treat oilfield wastewater in both South and North of China. When the processing time is 2.5 min at temperature 57°C, microwave demulsification has the best effect. Based on the research of microwave demulsifucation mechanism, a conclusion is reached that microwave heating effect and microwave catalytic eddect play a leading role on the demulsification.

High-Efficiency Extraction and Modification on the Coal Liquefaction Residue Using Supercritical Fluid with Different Types of Solvents

2016 ◽  
Vol 30 (5) ◽  
pp. 3917-3928 ◽  
Author(s):  
Xiongchao Lin ◽  
Shouyi Li ◽  
Fenghua Guo ◽  
Guangce Jiang ◽  
Xujun Chen ◽  
...  
Keyword(s):  
Supercritical Fluid ◽  
High Efficiency ◽  
Coal Liquefaction ◽  
Different Types ◽  
Coal Liquefaction Residue

An Efficient Volumetric-Error Measurement Method for Five-Axis Machine Tools

2005 ◽  
Author(s):  
Shih-Ming Wang ◽  
Han-Jen Yu ◽  
Hung-Wei Liao
Keyword(s):  
Machine Tools ◽  
Measurement Method ◽  
Degrees Of Freedom ◽  
High Efficiency ◽  
Low Cost ◽  
Volumetric Errors ◽  
Different Types ◽  
Measurement Methodology ◽  
Simple Measurement ◽  
Five Axis

Accurate measurement of volumetric errors plays an important role for error compensation for multi-axis machines. The error measurements for volumetric errors of five-axis machines are usually very complex and costly than that for three-axis machines. In this study, a direct and simple measurement method using telescoping ball-bar system for volumetric errors for different types of five-axis machines was developed. The method using two-step measurement methodology and incorporating with derived error models, can quickly determine the five degrees-of-freedom (DOF) volumetric errors of five-axis machine tools. Comparing to most of the current used measurement methods, the proposed method provides the advantages of low cost, high efficiency, easy setup, and high accuracy.

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