Optically transparent metamaterial absorber based on Jerusalem cross structure at S-band frequencies

2020 ◽  
Vol 34 (16) ◽  
pp. 2050175
Author(s):  
Yibo Tang ◽  
Longhui He ◽  
Anfeng Liu ◽  
Cuixiu Xiong ◽  
Hui Xu
Keyword(s):  
Reflection Loss ◽  
Indium Tin Oxide ◽  
Surface Current ◽  
Metamaterial Absorber ◽  
Attenuation Characteristic ◽  
Microwave Attenuation ◽  
Wide Range ◽  
Optically Transparent ◽  
Pet Film ◽  
Better Than

An optically transparent metamaterial absorber (MMA) has been demonstrated numerically and experimentally at the S-band. The designed MMA is composed of polymethyl methacrylate (PMMA), indium-tin-oxide (ITO) attached to polyethylene terephthalate (PET) film, and numerically provides effective absorption with reflection loss lower than −10 dB in the frequency range of 1.85–4.65 GHz. Experimental measurement shows the reflection loss of the proposed MMA is better than −10 dB from 2.00 GHz to 4.25 GHz, which agrees pretty well with the simulated results. Distributions of surface current, electromagnetic field and power loss density for the designed MMA are systematically investigated to explain microwave attenuation characteristic and loss mechanisms. More importantly, the prepared sample exhibits an optical transparency above 68% in the whole visible band, thus realizing a wide range of applications, such as optically transparent S-band absorbers.

scholarly journals Optically Transparent Metamaterial Absorber Using Inkjet Printing Technology

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3406
Author(s):  
Heijun Jeong ◽  
Manos M. Tentzeris ◽  
Sungjoon Lim
Keyword(s):  
Inkjet Printing ◽  
Indium Tin Oxide ◽  
Ground Plane ◽  
Metamaterial Absorber ◽  
Electromagnetic Simulation ◽  
Printing Technology ◽  
Absorption Bandwidth ◽  
Optically Transparent ◽  
Loop Pattern ◽  
Inkjet Printing Technology

An optically transparent metamaterial absorber that can be obtained using inkjet printing technology is proposed. In order to make the metamaterial absorber optically transparent, an inkjet printer was used to fabricate a thin conductive loop pattern. The loop pattern had a width of 0.2 mm and was located on the top surface of the metamaterial absorber, and polyethylene terephthalate films were used for fabricating the substrate. An optically transparent conductive indium tin oxide film was introduced in the bottom ground plane. Therefore, the proposed metamaterial absorber was optically transparent. The metamaterial absorber was demonstrated by performing a full-wave electromagnetic simulation and measured in free space. In the simulation, the 90% absorption bandwidth ranged from 26.6 to 28.8 GHz, while the measured 90% absorption bandwidth was 26.8–28.2 GHz. Therefore, it is successfully demonstrated by electromagnetic simulation and measurement results.

Low-frequency resistive-type metamaterial with broadband absorption by employing screen-printing method

2020 ◽  
Vol 34 (31) ◽  
pp. 2050298
Author(s):  
Longhui He ◽  
Cuixiu Xiong ◽  
Hui Xu ◽  
Sheng Liu ◽  
Yunchao Xu ◽  
...  
Keyword(s):  
Reflection Loss ◽  
Low Frequency ◽  
Surface Current ◽  
Transverse Magnetic ◽  
Metamaterial Absorber ◽  
Effective Bandwidth ◽  
Low Frequencies ◽  
Broadband Absorption ◽  
Microwave Absorbing Materials ◽  
Resistive Type

A broadband and wide-angled microwave absorber based on resistive-type metamaterial has been proposed and demonstrated in the low-frequency regime of 2–8 GHz. The minimum reflection loss of the absorption peak located at 5.27 GHz is −51.41 dB. Effective bandwidth better than −10 dB reflection loss is able to achieve 2.70 GHz in the range from 3.81 GHz to 6.51 GHz. The underlying physical mechanisms of electromagnetic wave energy attenuation are illustrated in detail by means of surface current, electromagnetic field and power loss density. Furthermore, the influence of structural dimensions on the attenuation properties of the proposed resistive-type metamaterial absorber is also investigated. More importantly, the designed resistive-type metamaterial absorber could operate well with incident angles changing from 0[Formula: see text] to 60[Formula: see text] under the transverse electric (TE) and transverse magnetic (TM) waves. Research results will be capable of providing guidance for the design and preparation of broadband microwave absorbing materials at low frequencies.

An ultra-broadband and optically transparent metamaterial absorber based on multilayer indium-tin-oxide structure

2021 ◽  
Vol 54 (16) ◽  
pp. 165301
Author(s):  
Guangsheng Deng ◽  
Kun Lv ◽  
Hanxiao Sun ◽  
Jun Yang ◽  
Zhiping Yin ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Metamaterial Absorber ◽  
Oxide Structure ◽  
Optically Transparent

Optically transparent and single-band metamaterial absorber based on indium-tin-oxide

2018 ◽  
Vol 29 (2) ◽  
pp. e21536 ◽  
Author(s):  
Zhiping Yin ◽  
Yujiao Lu ◽  
Sheng Gao ◽  
Jun Yang ◽  
Weien Lai ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Metamaterial Absorber ◽  
Single Band ◽  
Optically Transparent

Single-peak-regulation and wide-angle dual-band metamaterial absorber based on hollow-cross and solid-cross resonators

2020 ◽  
Vol 91 (3) ◽  
pp. 30901
Author(s):  
Yibo Tang ◽  
Longhui He ◽  
Jianming Xu ◽  
Hailang He ◽  
Yuhan Li ◽  
...  
Keyword(s):  
Transverse Electric ◽  
Surface Current ◽  
Dielectric Substrate ◽  
Transverse Magnetic ◽  
Metamaterial Absorber ◽  
Absorption Peak ◽  
Dual Band ◽  
Single Peak ◽  
Wide Angle ◽  
Surface Current Density

A dual-band microwave metamaterial absorber with single-peak regulation and wide-angle absorption has been proposed and illustrated. The designed metamaterial absorber is consisted of hollow-cross resonators, solid-cross resonators, dielectric substrate and metallic background plane. Strong absorption peak coefficients of 99.92% and 99.55% are achieved at 8.42 and 11.31 GHz, respectively, which is basically consistent with the experimental results. Surface current density and changing material properties are employed to illustrate the absorptive mechanism. More importantly, the proposed dual-band metamaterial absorber has the adjustable property of single absorption peak and could operate well at wide incidence angles for both transverse electric (TE) and transverse magnetic (TM) waves. Research results could provide and enrich instructive guidances for realizing a single-peak-regulation and wide-angle dual-band metamaterial absorber.

Research of the activity and viability of spermatozoa at different concentrations and proportions of diluents after incubation

2020 ◽  
pp. 88-95
Author(s):  
Svitlana Lobchenko ◽  
Tetiana Husar ◽  
Viktor Lobchenko
Keyword(s):  
Plasma Concentration ◽  
Incubation Time ◽  
Coefficient Of Variation ◽  
Incubation Medium ◽  
Wide Range ◽  
Series Of Experiments ◽  
The Subject ◽  
Boar Spermatozoa ◽  
Native Plasma ◽  
Better Than

The results of studies of the viability of spermatozoa with different incubation time at different concentrations and using different diluents are highlighted in the article. (Un) concentrated spermatozoa were diluented: 1) with their native plasma; 2) medium 199; 3) a mixture of equal volumes of plasma and medium 199. The experiment was designed to generate experimental samples with spermatozoa concentrations prepared according to the method, namely: 0.2; 0.1; 0.05; 0.025 billion / ml. The sperm was evaluated after 2, 4, 6 and 8 hours. The perspective of such a study is significant and makes it possible to research various aspects of the subject in a wide range. In this regard, a series of experiments were conducted in this area. The data obtained are statistically processed and allow us to highlight the results that relate to each stage of the study. In particular, in this article it was found out some regularities between the viability of sperm, the type of diluent and the rate of rarefaction, as evidenced by the data presented in the tables. As a result of sperm incubation, the viability of spermatozoa remains at least the highest trend when sperm are diluted to a concentration of 0.1 billion / ml, regardless of the type of diluent used. To maintain the viability of sperm using this concentration of medium 199 is not better than its native plasma, and its mixture with an equal volume of plasma through any length of time incubation of such sperm. Most often it is at this concentration of sperm that their viability is characterized by the lowest coefficient of variation, regardless of the type of diluent used, which may indicate the greatest stability of the result under these conditions. The viability of spermatozoa with a concentration of 0.1 billion / ml is statistically significantly reduced only after 6 or even 8 hours of incubation. If the sperm are incubated for only 2 hours, regardless of the type of diluent used, the sperm concentrations tested do not affect the viability of the sperm. Key words: boar, spermatozoa, sperm plasma, concentration, incubation, medium 199, activity, viability, rarefaction.

Effect of Contact Ratio on Spur Gear Dynamic Load With No Tooth Profile Modifications

1996 ◽  
Vol 118 (3) ◽  
pp. 439-443 ◽  
Author(s):  
Chuen-Huei Liou ◽  
Hsiang Hsi Lin ◽  
F. B. Oswald ◽  
D. P. Townsend
Keyword(s):  
Dynamic Load ◽  
Spur Gear ◽  
Tooth Size ◽  
Contact Ratio ◽  
Gear Dynamics ◽  
Wide Range ◽  
Gear Contact ◽  
Center Distance ◽  
Selection Of ◽  
Better Than

This paper presents a computer simulation showing how the gear contact ratio affects the dynamic load on a spur gear transmission. The contact ratio can be affected by the tooth addendum, the pressure angle, the tooth size (diametral pitch), and the center distance. The analysis presented in this paper was performed by using the NASA gear dynamics code DANST. In the analysis, the contact ratio was varied over the range 1.20 to 2.40 by changing the length of the tooth addendum. In order to simplify the analysis, other parameters related to contact ratio were held constant. The contact ratio was found to have a significant influence on gear dynamics. Over a wide range of operating speeds, a contact ratio close to 2.0 minimized dynamic load. For low-contact-ratio gears (contact ratio less than two), increasing the contact ratio reduced gear dynamic load. For high-contact-ratio gears (contact ratio equal to or greater than 2.0), the selection of contact ratio should take into consideration the intended operating speeds. In general, high-contact-ratio gears minimized dynamic load better than low-contact-ratio gears.

scholarly journals Optically transparent and very thin structure against electromagnetic pulse (EMP) using metal mesh and saltwater for shielding windows

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Duy Tung Phan ◽  
Chang Won Jung
Keyword(s):  
Electromagnetic Pulse ◽  
Low Cost ◽  
High Energy ◽  
Metal Plate ◽  
Optical Transparency ◽  
Shielding Effectiveness ◽  
Concrete Wall ◽  
Metal Mesh ◽  
Wide Range ◽  
Optically Transparent

AbstractAn electromagnetic pulse (EMP) with high energy can damage electronic equipment instantly within a wide range of thousands of kilometers. Generally, a metal plate placed inside a thick concrete wall is used against an EMP, but it is not suitable for an EMP shielding window, which requires not only strong shielding effectiveness (SE) but also optical transparency (OT). In this paper, we propose a very thin and optically transparent structure with excellent SE for EMP shielding window application. The proposed structure consists of a saltwater layer held between two glass substrates and two metal mesh layers on the outside of the glass, with a total thickness of less than 1.5 cm. The SE and OT of the structure are above 80 dB and 45%, respectively, which not only meet the requirement of EMP shielding for military purposes but also retain the procedure of good observation. Moreover, the OT of the structure can be significantly improved using only one metal mesh film (MMF) layer, while the SE is still maintained high to satisfy the required SE for home applicants. With the major advantages of low cost, optical transparency, strong SE, and flexible performance, the proposed structure can be considered a good solution for transparent EMP shielding windows.

scholarly journals Cache-efficient sweeping-based interval joins for extended Allen relation predicates

2021 ◽  
Author(s):  
Danila Piatov ◽  
Sven Helmer ◽  
Anton Dignös ◽  
Fabio Persia
Keyword(s):  
Data Structure ◽  
Experimental Evaluation ◽  
State Of The Art ◽  
Temporal Databases ◽  
Access Method ◽  
Wide Range ◽  
Interval Relation ◽  
Cache Efficient ◽  
Join Algorithms ◽  
Better Than

AbstractWe develop a family of efficient plane-sweeping interval join algorithms for evaluating a wide range of interval predicates such as Allen’s relationships and parameterized relationships. Our technique is based on a framework, components of which can be flexibly combined in different manners to support the required interval relation. In temporal databases, our algorithms can exploit a well-known and flexible access method, the Timeline Index, thus expanding the set of operations it supports even further. Additionally, employing a compact data structure, the gapless hash map, we utilize the CPU cache efficiently. In an experimental evaluation, we show that our approach is several times faster and scales better than state-of-the-art techniques, while being much better suited for real-time event processing.

An optically transparent broadband metamaterial absorber for radar-infrared bi-stealth

2021 ◽  
Vol 112 ◽  
pp. 110793
Author(s):  
Zhiqiang Gao ◽  
Qi Fan ◽  
Xiaoxia Tian ◽  
Cuilian Xu ◽  
Zhen Meng ◽  
...  
Keyword(s):  
Metamaterial Absorber ◽  
Optically Transparent
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