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Abstract

The article presents the research on the reduction of noise and vibrations carried out using screen theory and its implementation in practice. Acoustic screens are divided according to their application and structures. The article deals with the application of screens in practice, gives their theoretical evaluation and analyses influences of their structure and materials. The evaluation of positive and negative acoustic properties of the screens is given. The conclusion is that screen acoustic properties may be improved by including new elements into design of screens, thus increasing their efficiency in reducing noise effect. Theoretical calculations are performed, and the obtained results are analyzed. In conclusion, it is stated that cylindrical, semi-cylindrical or conical elements have to be applied in the screens.

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Authors and Affiliations

Danielius Guzas
Robertas Klimas
Vaclovas Tricys
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Abstract

With the improvement of the planning level of underground space, the location of the planned under-crossing tunnel can be known in advance when constructing the upper-span tunnel. Therefore, pre-protection measures can be taken in advance during the construction of the upper-span tunnel. A new pre-protection method of a pipe-jacking channel was proposed to reduce the adverse effects of under-crossing shield tunnels. Numerical simulations of different pre-protection schemes were carried out using the finite element method to analyze its deformation control effect. The simulation results show that the deformation control effect of the gantry reinforcement scheme is the most significant. It is shown that the displacement of the pipe-jacking channel is more significantly suppressed with pre-protection measures than without preventive protection measures. The vertical displacement curve of the pipe-jacking channel exhibits a “W” shape after the construction of the double-lane shield underpass. By comparing the three different working conditions, it is found that the maximum vertical displacement and surface settlement of the pipe-jacking channel greatly reduced the gantry reinforcement pre-protection. Compared with Case 3, the effect of the pre-protection measures adopted in Case 2 was less obvious, which indicated that the form of the pre-protection had an important influence on controlling the deformation of the pipe-jacking channel.
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Authors and Affiliations

Yunliang Cui
1 2
Xukun Yang
1 2
ORCID: ORCID
Xinquan Wang
1 2
Hongguo Diao
1 2
Xiao Li
1 2
Yuanyuan Gao
1 2

  1. School of Engineering, Hangzhou City University, Hangzhou 310015, PR China
  2. Key Laboratory of Safe Construction and Intelligent Maintenance for Urban Shield Tunnels of Zhejiang Province, Hangzhou 310015, PR China
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Abstract

Both corrosion and abrasion remove materials from some engineering components such as impact coal crusher hammers, pulverizer rings, chute liner, and rolls or molds. Intensive research has been done on improving the wear resistance of high chromium alloys, however, studies into corrosion resistance of high chromium alloys are insufficient. In order to determine the amount of ferroniobium addition in the wire to achieve the best corrosion resistance, and find out the mechanism of ferroniobium enhancing the corrosion resistance of the welding overlays, the high-Cr iron-based welding overlays with different niobium addition were fabricated by using self-made self-shielded metal-cored wires and their acidic corrosion resistance in 3.5 wt.% NaCl solution + 0.01 mol/L HCl solution were investigated by electrochemical corrosion test. The microstructure and corrosion morphology were characterized by OM, SEM, XRD and EDS. The polarization curves and values of I corr, E corr and Rc indicate the corrosion resistance is at the highest with 3.6 wt.% niobium addition, and at the lowest when the niobium addition is 10.8 wt.%. The corrosion of welding overlay occurs in the matrix of microstructure. With the increase of niobium addition from 3.6 wt.% to 10.8 wt.%, the proportion of network eutectic structure in the welding overlay is increased. Up to 10.8 wt.%, the microstructure is transformed from hypereutectic structure into eutectic one, leading to a higher acceleration of corrosion rate. When niobium addition reaches 14.4 wt.%, the welding overlay is transformed into a hypoeutectic structure. The addition of niobium element consumes carbon element in the alloy, which makes the increase of chromium content in the final solidified matrix, leading to an improvement in corrosion resistance.
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Authors and Affiliations

Dashuang Liu
1 2 3
Yucheng Wu
1
Weimin Long
2 4
Ping Wei
3
Rui Wang
3
ORCID: ORCID
Wei Zhou
1 5

  1. Hefei University of Technology, School of Material Science and Engineering, Hefei 230009, China
  2. Zhengzhou Research Institute of Mechanical Engineering Co., Ltd., Zhengzhou 450001, China
  3. Jiangsu University of Science and Technology, School of Material Science and Engineering, Zhenjiang 212003, China
  4. China Innovation Academy of Intelligent Equipment (Ningbo) Co., Ltd, Ningbo 315700, China
  5. School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
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Abstract

Recent papers and studies over the course of last three years have shown that COVID-19 has a negative impact on the speech communication quality between people. This paper presents an influence analysis of the curvature shape of protective transparent shields on the speech signal. Five shields made of the same material and dimensions but with different curvatures were analyzed, from a completely flat to a very curved shield which has the same shape of curvature at its top and bottom and covers the entire face. The influence of the shield is analyzed with two types of experiments – one using dummy head with integrated artificial voice device, and the other using real speakers (female and male actors). It has been shown that usage of protective shields results in a relative increase in the speech signal level, in the frequency range of around 1000 Hz, compared to the situation when protective shields are not used. The relative increase in speech signal levels for large-curvature shields can be up to 8 dB. The possible causes of this phenomenon have been analyzed and examined.
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Authors and Affiliations

Miloš Bjelic
1
ORCID: ORCID
Miomir Mijic
1
ORCID: ORCID
Tatjana Miljkovic
1
ORCID: ORCID
Dragana Šumarac Pavlovic
1
ORCID: ORCID

  1. School of Electrical Engineering, University of Belgrade Belgrade, Serbia
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Abstract

Since the establishment of the People’s Republic of China, the country has made significant progress in tunnel construction, transforming from a “weak tunnel nation” to a “strong tunnel nation.” As of 2022, China has undertaken more than 60 projects involving large-diameter shield tunnels. To promote the sustainable and high-quality development of large-diameter shield tunnels in China, this article systematically reviews the development history of large-diameter shield tunnels, summarizes the current projects in the country, and addresses various aspects such as construction technology management, design technology, ecological conservation, safety, and intelligence. The article also provides suggestions for the development of large-diameter shield tunnels in China, with the aim of playing a proactive role in promoting their advancement.
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Authors and Affiliations

Wei Qiu
1
ORCID: ORCID
Xin Dong
1
ORCID: ORCID
Linjian Su
1
ORCID: ORCID
Xingwei Xue
2
ORCID: ORCID
Kexin Zhang
2
ORCID: ORCID

  1. Engineering Department, Guangzhou Expressway Co., LTD, China
  2. School of Transportation and Surveying Engineering, Shenyang Jianzhu University, China
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Abstract

This paper gives a description of the head shield of Alona protzi, a rare species of Cladocera (water fleas) whose separated head shield has not yet been described in detail. Subfossil head shields of A. protzi were found in sediment cores taken from lakes in Denmark, Sweden, Finland, Estonia and Poland. Despite the rarity of the species this suggests a wide distribution of A. protzi in northern Europe. The ecology of A. protzi is poorly known. The environmental spectrum of the finding sites was wide and ranged from relatively nutrient poor clear water lakes to eutrophic turbid water lakes, indicating that A. protzi is not narrowly restricted. Most of the lakes were, however, meso-eutrophic with neutral to high pH, and with a relatively low abundance of submerged macrophytes. However, we cannot exclude the possibility that A. protzi mainly lives in groundwater and is only occasionally transported into lakes.

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Authors and Affiliations

Rikke Bjerring
Mirva Nykänen
Kaarina Sarmaja-Korjonen
Artem Sinev
Karina Jensen
Liisa Nevalainen
Krystyna Szeroczyńska
Edyta Zawisza
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Abstract

In longwall coal exploitation, problems with the proper functioning of the powered shield support often occur. In many cases, it results from the insufficient load-bearing capacity of the ground (floor) and the inability to achieve the set or yield pressure of the shield support. The improper functioning of the shield support may also result from its construction and the lack of optimisation to work effectively on a weak mine floor. This paper presents an attempt to optimise the operating conditions of the base of two-legged shield support based on the field observations and results of the PFC3D numerical calculation. In the framework of the numerical calculations, the impact of the width of the base and the location of the hydraulic legs on the working conditions of shield support on a weak floor were analysed.
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Authors and Affiliations

Sylwester Rajwa
1
ORCID: ORCID
Sven Bock
2
ORCID: ORCID

  1. Central Mining Institute (GIG), 1 Gwarków Sq., 40-166 Katowice, Poland
  2. DMT GmbH, Germany
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Abstract

With the development of wireless power transfer technology, more and more attention has been paid to its electromagnetic safety. In this paper, a novel hybrid shielding structure composed of the innermost fan-shaped ferrite, the interlayer nanocrystalline strip and the outermost aluminum foil is proposed to shield the electromagnetic field of the inductive power transfer system. Eight structure parameters of the proposed shielding are optimized by finite element simulation, in order to reduce the magnetic leakage of the system and improve the utilization rate of shielding materials. In addition, the proposed structure is compared with two types of typical double-layer hybrid shielding from the perspectives of the weight, the coupling coefficient and the magnetic flux leakage. Both simulation and experiment results show that the cost and weight of the proposed shield are about 60% lower than the traditional disk shield. Moreover, the shielding layer proposed in this paper can not only effectively reduce the magnetic flux leakage of the system, but also maintain a high coupling coefficient.
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Bibliography

[1] Zhang Z., Pang H., Georgiadis A., Cecati C., Wireless Power Transfer—An Overview, IEEE Transactions on Industrial Electronics, vol. 66, no. 2, pp. 1044–1058 (2019).
[2] Kalwar K.A., Aamir M., Mekhilef S., Inductively coupled power transfer (ICPT) for electric vehicle charging – A review, Renewable and Sustainable Energy Reviews, vol. 47, pp. 462–475 (2015).
[3] Machura P., Li Q., A critical review on wireless charging for electric vehicles, Renewable and Sustainable Energy Reviews, vol. 104, pp. 209–234 (2019).
[4] Li H., Wang C., Liu Y., Yue R., Research on Single-Switch Wireless Power Transfer System Based on SiC MOSFET, IEEE Access, vol. 7, pp. 163796–163805 (2019).
[5] Zheng J., Wang C., Xia D., Design and analysis of the ferrite air-gapped cores for a resonant inductor[ J], Archives of Electrical Engineering, vol. 67, pp. 579–589 (2018).
[6] Xu H., Wang C., Xia D., Liu Y., Design of Magnetic Coupler for Wireless Power Transfer, Energies, vol. 12, no. 15 (2019).
[7] Christ A., Douglas M.,Nadakuduti J.,Kuster N., Assessing Human Exposure to Electromagnetic Fields from Wireless Power Transmission Systems, Proceedings of the IEEE, vol. 101, no. 6, pp. 1482–1493 (2013).
[8] Ding P., Bernard L., Pichon L., Razek A., Evaluation of Electromagnetic Fields in Human Body Exposed to Wireless Inductive Charging System, IEEE Transactions on Magnetics, vol. 50, no. 2, pp. 1037–1040 (2014).
[9] International Commission on Non-Ionizing Radiation Protection Guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz), Health Phys., vol. 99, pp. 818–836 (2010).
[10] Tan L., Elnail K.E.I., Ju M., Huang X., Comparative Analysis and Design of the Shielding Techniques in WPT Systems for Charging EVs, Energies, vol. 12, no. 11 (2019).
[11] Choi S.Y., Gu B.W., Lee S.W., Lee W.Y., Huh J., Rim C.T., Generalized Active EMF Cancel Methods forWireless Electric Vehicles, IEEE Transactions on Power Electronics, vol. 29, no. 11, pp. 5770–5783 (2014).
[12] Zhu Q., Zhang Y., Guo Y., Liao C.,Wang L.,Wang L., Null-Coupled Electromagnetic Field Canceling Coil for Wireless Power Transfer System, IEEE Transactions on Transportation Electrification, vol. 3, no. 2, pp. 464–473 (2017).
[13] Zeng H., Liu Z., Hou Y., Hei T., Zhou B., Optimization of Magnetic Core Structure for Wireless Charging Coupler, IEEE Transactions on Magnetics, vol. 53, no. 6, pp. 1–4 (2017).
[14] Houji L., Chunfang W., Zhihao W., Dan L., Research of shield structure for wireless power transfer system, Advanced Technology of Electrical Engineering and Energy, vol. 38, no. 5, pp. 74–83 (2019).
[15] Stergiou C.A., Zaspalis V., Impact of Ferrite Shield Properties on the Low-Power Inductive Power Transfer, IEEE Transactions on Magnetics, vol. 52, no. 8, pp. 1–9 (2016).
[16] Wen F., Huang X., Optimal Magnetic Field Shielding Method by Metallic Sheets in Wireless Power Transfer System, Energies, vol. 9, no. 9 (2016).
[17] Li J., Huang X., Chen C., Tan L., Wang W., Guo J., Effect of metal shielding on a wireless power transfer system, AIP Advances, vol. 7, no. 5 (2017).
[18] Park H.H.,Kwon J.H.,Kwak S.I., Ahn S., Magnetic Shielding Analysis of a Ferrite Plate with a Periodic Metal Strip, IEEE Transactions on Magnetics, vol. 51, no. 8, pp. 18 (2015).
[19] Park H.H., Kwon J.H., Kwak S.I., Ahn S., Effect of Air-Gap Between a Ferrite Plate and Metal Strips on Magnetic Shielding, IEEE Transactions on Magnetics, vol. 51, no. 11, pp. 1–4 (2015).
[20] Kim H., Song C., Kim D., Jung D.H., Kim I., Kim Y., Kim J., Ahn S., Kim J., Coil Design and Measurements of Automotive Magnetic Resonant Wireless Charging System for High-Efficiency and Low Magnetic Field Leakage, IEEE Transactions on Microwave Theory and Techniques, vol. 64, no. 2, pp. 1–18 (2016).
[21] Kim S., Covic G.A., Boys J.T., Tripolar Pad for Inductive Power Transfer Systems for EV Charging, Transactions on Power Electronics, vol. 32, no. 7, pp. 5045–5057 (2017).
[22] Kim M., Byun J., Lee B.K., Performance Analysis of Magnetic Power Pads for Inductive Power Transfer Systems with Ferrite Structure Variation, Journal of Electrical Engineering and Technology, vol. 12, pp. 1211–1218 (2017).
[23] Budhia M., Boys J.T., Covic G.A., Huang C., Development of a Single-Sided Flux Magnetic Coupler for Electric Vehicle IPT Charging Systems, IEEE Transactions on Industrial Electronics, vol. 60, no. 1, pp. 318–328 (2013).
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Authors and Affiliations

Yun Rui Liu
1
Chunfang Wang
1
Dongwei Xia
1
Rui Yue
1

  1. Qingdao University, China
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Abstract

This article provides an optimized solution to the problem of passive shielding against static magnetic fields with any number of spherical shells. It is known, that the shielding factor of a layered structure increases in contrast to a single shell with the same overall thickness. For the reduction of weight and cost by given material parameters and available space the best system for the layer positions has to be found. Because classic magnetically shielded rooms are very heavy, this system will be used to develop a transportable Zero-Gauss-Chamber. To handle this problem, a new way was developed, in which for the first time the solution with regard to shielding and weight was optimized. Therefore, a solution for the most general case of spherical shells was chosen with an adapted boundary condition. This solution was expanded to an arbitrary number of layers and permeabilities. With this analytic solution a differential evolution algorithm is able to find the best partition of the shells. These optimized solutions are verified by numerical solutions made by the Finite Element Method (FEM). After that the solutions of different raw data are determined and investigated.
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Bibliography

[1] Schiebold K., Zerstörungsfreie Werkstoffprüfung – Magnetpulverprüfung, Springer-Verlag (2015).
[2] Farolfi A., Trypogeorgos D., Colzi G., Fava E., Lamporesi G., Ferrari G., Design and characterization of a compact magnetic shield for ultracold atomic gas experiments, Review of Scientific Instruments, 90.11, 115114 (2019), DOI: 10.48550/arXiv.1907.06457.
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[12] Maurer MagneticAG, Restmagnetismus – das verkannte Problem, JOT Journal für Oberflächentechnik, 57, pp. 104–105 (2017).
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[15] Reutov Y.Y., Choice of the number of shells for a spherical magnetostatic shield, Russian Journal of Non-destructive Testing, 37.12, pp. 872–878 (2001).
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Authors and Affiliations

Patrick Alexander Ralf
1
ORCID: ORCID
Christian Kreischer
1

  1. Helmut Schmidt University, University of the Federal Armed Forced Hamburg, Germany
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Abstract

Growing awareness for occupational safety in the welding environment needs a sustainable welding system. Welding gases releases toxic tiny particles and gases that inflict severe health consequences in the weld zone are unsolicited. Some of the other main adverse effects are lung disease, hemoptysis, pulmonary inflammation, pneumoconiosis, etc. GMAW procedure has been used for welding 316L stainless steel plates of 3 mm, 5 mm, and 6 mm. Various current configurations with gas flow rate of 5 LPM, 10 LPM and 15 LPM were also used to achieve optimum butt joint performance and to reduce the production rate of fume contributing to cost-effectiveness. In this research a cost-effective fume extraction hood was fabricated for measuring Emission factor produced during welding. Various shielding gas compositions including Pure Argon, Pure CO2, 92% Ar+8% CO2 and 88% Ar+12% CO2 were used to determine the best operating parameters in the GMAW method. To satisfy the latest Permissible Exposure Limit (PEL) legislation, optimum technical parameters for efficient welding were acknowledged with the lowest emission factor. A maximum reduction of Emission factor can be achieved by using Pure Argon. The inclusion of CO2 as a shielding gas mixture gives higher emission factor when compared to Pure Argon. Very low emission factor were witnessed in this research when compared to previous investigations. Lower emission factor of 2941.17 mg /kg of electrode, 4411.76 mg/kg of electrode and 7352.94 mg/kg of electrode were obtained for pure argon as shielding gas with 150 A welding current.
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Authors and Affiliations

K.V. Satheesh Kumar
1
ORCID: ORCID
P. Selvakumar
2
ORCID: ORCID
K.R. Uvanshankar
1
ORCID: ORCID
S. Thirunavukarasu
1
ORCID: ORCID
V. Vijay Anand
1
ORCID: ORCID
D. Vishal
1
ORCID: ORCID

  1. Department of Mechanical Engineering, Kongu Engineering College, Erode- 638060, Tamilnadu, India
  2. Department of Chemistry, Vivekanandha College of Arts & Sciences for Women, Tiruchengode- 637205, Tamilnadu, India
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Abstract

This paper presents an investigation into effect of nitrogen content of shielding gas mixture on weld geometry, microstructure and hardness of pulsed laser welded 2205 duplex stainless steel. Full penetration autogenous welding was performed on 2 mm thick plates using a low power pulsed Nd: YAG laser. light and scanning electron microscopy were used to study the resulting microstructures. It is observed that 2 mm full penetrated joint decreases to 1.8 mm by dominating nitrogen in argon-nitrogen mixture. Different morphologies of austenite phase as well as an increase of 8% of its content can be observed in pure nitrogen shielded welds. Average weld grain size in sample which is welded in nitrogen atmosphere stands at approximately 41 μm which is smaller than that of argon atmosphere which is about 51 μm. Micro-hardness test reveals that hardness values increase from 280 HV in base metal to 307 HV in weld center line and the shielding gas mixture does not significantly influence the weld hardness.

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Authors and Affiliations

E. Hajibaba Gozarganji
A. Farnia
M. Ebrahimnia
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Abstract

The running speed of high-speed trains in the tunnel is as high as 350 km, which is very sensitive to the construction disturbance of the new shield tunnel. Therefore, it is of positive significance to study the influence of shield tunneling on existing high-speed railway lines and tunnel structures and control standards. Combined with centrifuge test and three-dimensional numerical simulation, the dynamic response of shield tunnel undercrossing existing high-speed railway tunnel is studied, and the influence of settlement joint and steel pipe pile reinforcement on existing tunnel is analyzed. Studies have shown that the existence of existing tunnels will reduce the surface settlement caused by tunnel excavation, but this shielding effect will be reduced if the influence of construction joints is considered. Therefore, if the construction joint is not considered in the numerical calculation, the ground deformation will be underestimated and the mechanical performance of the existing tunnel structure will be overestimated. In addition, steel pipe piles can effectively control the settlement of existing tunnels.
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Authors and Affiliations

Ruizhen Fei
1 2
ORCID: ORCID
Limin Peng
1
ORCID: ORCID
Chunlei Zhang
2
ORCID: ORCID
Jiqing Zhang
2
ORCID: ORCID
Peng Zhang
2
ORCID: ORCID

  1. Central South University, School of Civil Engineering, Changsha, 410075, China
  2. China Railway Design Corporation, Tianjin, 300142, China
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Abstract

Pea gravel is a kind of a coarse aggregate with a specific particle size used to fill the annular gap between the lining segments and the surrounding ground when tunnel construction with shield machines is performed in hard rock. The main purpose of the present study is to propose quantitative morphological indices of the pea gravel and to establish their relations with the void content of the aggregate and the compressive strength of the mixture of pea gravel and slurry (MPS). Results indicate that the pea gravel of the crushed rock generally have a larger void content than that of the river pebble, and the grain size has the highest influence on the void ratio. Elongation, roughness and angularity have moderate influences on the void ratio. The content of the oversize or undersize particles in the sample affects the void ratio of the granular assembly in a contrary way. The compressive strength of the MPS made with the river pebble is obviously smaller than that of the MPS made with the crushed rock. In the crushed rock samples, the compressive strength increases with the increase of the oversize particle content. The relations between the morphological properties and the void content, and the morphological properties and the compressive strength of the MPS are expressed as regression functions. The outcomes of this study would assist with quality assessments in TBM engineering for the selection of the pea gravel material and the prediction of the compressive strength of the MPS.
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Bibliography


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Authors and Affiliations

Jinliang Zhang
1
Qiuxiang Huang
2
ORCID: ORCID
Chao Hu
2
Zhiqiang Wang
1

  1. Yellow River Engineering Consulting Co., Ltd. Zhengzhou, Henan, China
  2. State Key Lab of Geohazard Prevention and Environment Protection (SKLGP), Chengdu University of Technology (CDUT), Chengdu, Sichuan, China
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Abstract

The use of subway tunnel engineering technology has become more professional and refined with the growth of society and the advancement of science and technology. The initial construction process of a subway tunnel shield is the most critical part of the entire engineering system. Shield launching period construction is the most prone to accidents in the shield construction process, directly related to the smooth through the shield tunnel. The line 1 of Ho Chi Minh (HCM) Metro is the first subway line, the full length of 19.7 km, the underground road length of 2.6 km from km 0 + 615 to km 2 + 360, from Ben Thanh market, and then through the Sai Gon river and 14 station (including 3 underground stations and 11 elevated stations), reach Suoi Tien park and is located in Long Binh area station, underground building blocks including Ben Thanh market station to Opera House station interval, Opera House station, Opera House station to Ba Son station interval. This paper selects Shield launching period of Opera House station to Ba Son shaft interval as an example, analyze the key construction technology, construction control parameters and launching considerations of shield machine.
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Authors and Affiliations

Xuan Loi Nguyen
1
Li Wu
1
ORCID: ORCID
Khanh Tung Nguyen
2
Quang Anh Bui
2
Huy Hoang Nguen
2
Hoang Phuong Luu
3

  1. Faculty of Engineering, China University of Geosciences (Wuhan), No. 388 Lumo Road, Wuhan 430074, Hubei, P.R. China
  2. FECON UCC., JSC, 19th floors, CEO Tower, Lot HH2-1, Me Tri Ha Urban Area, Pham Hung road, Me Triward, Nam Tu Liem district, Hanoi city, Vietnam
  3. FECON., JSC, 14th floors, CEO Tower, Lot HH2-1, Me Tri Ha Urban Area, Pham Hung road, Me Tri ward, Nam Tu Liem district, Hanoi city, Vietnam
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Abstract

This article provides a thorough description of a range of non-standard application cases in which EMC laboratories can be used other than those traditionally associated with this kind of facilities. The areas covered here include investigations of: wireless and radio systems (such as IoT and broadband radio systems) also that require ultra-high operational dynamic range, emulation of interference-free and/or heavilymultipath propagation environment, shielding effectiveness of cabinets and materials (i.e. thin, light and flexible as textiles as well as heavy and thick such as building construction elements).

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Authors and Affiliations

Kamil Staniec
Zbigniew Jóskiewicz
Jarosław Janukiewicz
Tadeusz Więckowski

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