shielding effect
Recently Published Documents


TOTAL DOCUMENTS

962
(FIVE YEARS 302)

H-INDEX

32
(FIVE YEARS 5)

2022 ◽  
Vol 14 (2) ◽  
pp. 251
Author(s):  
Yuanzheng Wang ◽  
Hui Qin ◽  
Yu Tang ◽  
Donghao Zhang ◽  
Donghui Yang ◽  
...  

Ground penetrating radar (GPR) is one of the most recommended tools for routine inspection of tunnel linings. However, the rebars in the reinforced concrete produce a strong shielding effect on the electromagnetic waves, which may hinder the interpretation of GPR data. In this work, we proposed a method to improve the identification of tunnel lining voids by designing a generative adversarial network-based rebar clutter elimination network (RCE-GAN). The designed network has two sets of generators and discriminators, and by introducing the cycle-consistency loss, the network is capable of learning high-level features between unpaired GPR images. In addition, an attention module and a dilation center part were designed in the network to improve the network performance. Validation of the proposed method was conducted on both synthetic and real-world GPR images, collected from the implementation of finite-difference time-domain (FDTD) simulations and a controlled physical model experiment, respectively. The results demonstrate that the proposed method is promising for its lower demand on the training dataset and the improvement in the identification of tunnel lining voids.


2021 ◽  
Vol 13 (1) ◽  
pp. 13
Author(s):  
Quanlei Zhang ◽  
Chunfang Wang ◽  
Lingyun Yang ◽  
Zhihao Guo

With the development of wireless power transfer (WPT), the wireless charging has become a research hotspot. This paper proposes a novel single-switch hybrid compensation topology, which can change the compensation network to realize the constant-current (CC) and constant-voltage (CV) output. The zero voltage switching (ZVS) margin can be designed to increase the stability of the system. In addition, the magnetic coupler adopts a composite shielding structure composed of ferrite, nanocrystalline, and aluminium foil. The composite shielding structure has a better shielding effect on magnetic flux leakage, and its weight is lighter. The composite shielding structure is expected to be used in the wireless charging system of electric vehicles (EVs). Finally, an experimental prototype is built to verify the theoretical analysis, and the maximum efficiency can reach 91.4%.


2021 ◽  
Vol 12 (1) ◽  
pp. 276
Author(s):  
Hui Wang ◽  
Huan Li ◽  
Xuhui He

The aerodynamic features of a train and flat closed-box bridge system may be highly sensitive to train-bridge aero interactions. For the generally utilized railway bridge-deck with two tracks (the upstream and downstream ones), the aero interactions above are occupied-track-dependent. The present paper thus aims to reveal the aero interactions stated above via a series of wind tunnel tests. The results showed that the aero interactions of the present train-bridge system display four typical behaviors, namely, the underbody flow restraining effect, bridge deck shielding effect, flow transition promoting effect, and the flow separation intensifying effect. The above four aero interactions result in obvious reductions in the aerodynamic forces of the train in wind angle of attack α of [−4°, 12°] and in the static stall angle of the bridge-deck, and leads to sensible increases in the absolute values of the bridge aerodynamic forces in α of [−4°, 12°]. Upon comparing the results with the same train and bridge system but with the train model mounted on the downstream track, the quasi-Reynolds number effect was non-detectable when the train model was moved to the upstream track. Thus, no drag crisis and other saltatory aerodynamic behaviors were observed in the present study in α of [0°, 12°].


2021 ◽  
pp. 0734242X2110656
Author(s):  
Noemie Courtois ◽  
Isabelle Pochard ◽  
Marielle Remery ◽  
Jean-Yves Hihn ◽  
Laurent Tourneret

The objective of this study was to characterise the anaerobic degradation of three paper mill waste water treatment residues in the shape of sludges and to correlate this anaerobic digestion to the physico-chemical characteristics of the paper sludges. After a deep characterisation of each paper sludge in their initial stage, several parameters were analysed on each paper sludge in mesophilic conditions for 40–50 days: pH, conductivity, chemical oxygen demand, total organic acids and organic fibres degradation. A special care was taken to identify and quantify the volatile fatty acids (VFAs) produced by the digestion using gas chromatography coupled with a mass spectrometer. The results showed that in paper sludges, cellulose mainly degrades over time while the degradation of the other fibres (hemicellulose and lignin) is limited. Consequently, the greater the cellulose content in a paper sludge, the greater the digestion and formation of VFAs. However, not all the cellulose degrades because of a shielding effect of lignin on cellulose, and a pH buffering effect of the calcium carbonate present in the paper sludges limits the hydrolysis-acidogenesis step of the anaerobic digestion. Finally, the gas chromatography–mass spectrometry (GC-MS) investigations showed that acetic acid is the main VFA produced by the anaerobic digestion of paper sludges. This work helps predicting paper mill sludge evolution in the purpose of using them in circular economy.


Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8419
Author(s):  
Mikel Celaya-Echarri ◽  
Leyre Azpilicueta ◽  
Fidel Alejandro Rodríguez-Corbo ◽  
Peio Lopez-Iturri ◽  
Victoria Ramos ◽  
...  

The densification of multiple wireless communication systems that coexist nowadays, as well as the 5G new generation cellular systems advent towards the millimeter wave (mmWave) frequency range, give rise to complex context-aware scenarios with high-node density heterogeneous networks. In this work, a radiofrequency electromagnetic field (RF-EMF) exposure assessment from an empirical and modeling approach for a large, complex indoor setting with high node density and traffic is presented. For that purpose, an intensive and comprehensive in-depth RF-EMF E-field characterization study is provided in a public library study case, considering dense personal mobile communications (5G FR2 @28 GHz) and wireless 802.11ay (@60 GHz) data access services on the mmWave frequency range. By means of an enhanced in-house deterministic 3D ray launching (3D-RL) simulation tool for RF-EMF exposure assessment, different complex heterogenous scenarios of high complexity are assessed in realistic operation conditions, considering different user distributions and densities. The use of directive antennas and MIMO beamforming techniques, as well as all the corresponding features in terms of radio wave propagation, such as the body shielding effect, dispersive material properties of obstacles, the impact of the distribution of scatterers and the associated electromagnetic propagation phenomena, are considered for simulation. Discussion regarding the contribution and impact of the coexistence of multiple heterogeneous networks and services is presented, verifying compliance with the current established international regulation limits with exposure levels far below the aforementioned limits. Finally, the proposed simulation technique is validated with a complete empirical campaign of measurements, showing good agreement. In consequence, the obtained datasets and simulation estimations, along with the proposed RF-EMF simulation tool, could be a reference approach for the design, deployment and exposure assessment of the current and future wireless communication technologies on the mmWave spectrum, where massive high-node density heterogeneous networks are expected.


2021 ◽  
Vol 3 ◽  
pp. e20
Author(s):  
Naoki Matsuo ◽  
Natsuko Goda ◽  
Takeshi Tenno ◽  
Hidekazu Hiroaki

Background Intrinsically disordered proteins (IDPs) have been shown to exhibit cryoprotective activity toward other cellular enzymes without any obvious conserved sequence motifs. This study investigated relationships between the physical properties of several human genome-derived IDPs and their cryoprotective activities. Methods Cryoprotective activity of three human-genome derived IDPs and their truncated peptides toward lactate dehydrogenase (LDH) and glutathione S-transferase (GST) was examined. After the shortest cryoprotective peptide was defined (named FK20), cryoprotective activity of all-D-enantiomeric isoform of FK20 (FK20-D) as well as a racemic mixture of FK20 and FK20-D was examined. In order to examine the lack of increase of thermal stability of the target enzyme, the CD spectra of GST and LDH in the presence of a racemic mixture of FK20 and FK20-D at varying temperatures were measured and used to estimate Tm. Results Cryoprotective activity of IDPs longer than 20 amino acids was nearly independent of the amino acid length. The shortest IDP-derived 20 amino acid length peptide with sufficient cryoprotective activity was developed from a series of TNFRSF11B fragments (named FK20). FK20, FK20-D, and an equimolar mixture of FK20 and FK20-D also showed similar cryoprotective activity toward LDH and GST. Tm of GST in the presence and absence of an equimolar mixture of FK20 and FK20-D are similar, suggesting that IDPs’ cryoprotection mechanism seems partly from a molecular shielding effect rather than a direct interaction with the target enzymes.


Sign in / Sign up

Export Citation Format

Share Document