• Title/Summary/Keyword: Tunnel Noise

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Connection stiffness reduction analysis in steel bridge via deep CNN and modal experimental data

  • Dang, Hung V.;Raza, Mohsin;Tran-Ngoc, H.;Bui-Tien, T.;Nguyen, Huan X.
    • Structural Engineering and Mechanics
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    • v.77 no.4
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    • pp.495-508
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    • 2021
  • This study devises a novel approach, namely quadruple 1D convolutional neural network, for detecting connection stiffness reduction in steel truss bridge structure using experimental and numerical modal data. The method is developed based on expertise in two domains: firstly, in Structural Health Monitoring, the mode shapes and its high-order derivatives, including second, third, and fourth derivatives, are accurate indicators in assessing damages. Secondly, in the Machine Learning literature, the deep convolutional neural networks are able to extract relevant features from input data, then perform classification tasks with high accuracy and reduced time complexity. The efficacy and effectiveness of the present method are supported through an extensive case study with the railway Nam O bridge. It delivers highly accurate results in assessing damage localization and damage severity for single as well as multiple damage scenarios. In addition, the robustness of this method is tested with the presence of white noise reflecting unavoidable uncertainties in signal processing and modeling in reality. The proposed approach is able to provide stable results with data corrupted by noise up to 10%.

Blasting Design for Large Shaft in Urban Area Considering Noise and Vibration -Singapore Transmission Cable Tunnel EW2- (소음 및 진동을 고려한 도심지 내 대단면 수직구 발파설계 사례 -싱가포르 Transmission Cable Tunnel EW2 공구-)

  • Kim, Julie;Lee, Hyo;Kim, Dave;Ko, Tae-Young;Lee, Simon
    • Explosives and Blasting
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    • v.31 no.1
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    • pp.55-63
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    • 2013
  • With increasing needs in power, Singapore is requiring stronger power transmission. Singapore Transmission Cable Tunnel is underground tunnel for transmission system installation such as 400 kV cable. This Transmission Cable Tunnel is 35 km long in total. The North-South Transmission Cable Tunnel is 18.5 km long and there is a total of three (3) contracts; NS1, NS2 and NS3 in respect of the design and construction. The East-West Transmission Cable Tunnel is 16.5 km long, and also there is a total of three (3) contracts; EW1, EW2 and EW3. Among of them, SK E&C has been awarded and operating contract EW2 and NS2. In scope of works, each contract has 3 to 4 shafts which connect aboveground and underground high volt cable and those shafts are used as TBM launching shafts during construction. Transmission Cable Tunnel is undercrossing middle of Singapore and most of shafts are located in urban area. Thus, optimal blasting design satisfying high blasting efficiency as well as blasting vibration limit of Singapore is highly required. Blasting design for large shaft of Singapore Transmission Cable Tunnel follows blasting vibration limits in Singapore and reflects our blasting engineering skills. With Singapore Transmission Cable Tunnel Contract EW2, it is expected that our excellent blasting engineering and performance skills can be delivered to the world.

Nonlinear Seismic Performance Evaluation of an Operating TBM(Tunnel Boring Machine) Tunnel (공용 중인 TBM(Tunnel Boring Machine) 터널의 비선형 내진성능 평가 )

  • Byoung-Il Choi;Dong-Ha Lee;Jin-Woo Jung;Si-Hyun Park
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.28 no.5
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    • pp.1-9
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    • 2024
  • Recently, the TBM tunnel construction method has been in the spotlight as tunnel excavation under urban areas such as the Metropolitan Rapid Transit (GTX) has been actively carried out. Although the construction cost of the TBM tunnel is high, it is relatively free from noise and vibration compared to the NATM tunnel method, so it is well known to be a suitable construction method for application to the lower part of urban areas. In particular, when the stratum passes through the shallow section, it can have a great impact on existing upper structures and obstacles, so accurate numerical analysis considering various variables is required when designing the TBM tunnel. Unlike other tunnel construction methods, TBM tunnels build linings by assembling factory-made segments. Unlike NATM tunnels, segment lining has connections between segments, so how to the connection status between segments is reflected can have a significant impact on securing the reliability of analysis results. Therefore, in this paper, a segment joint model(Janssen Model) was applied to the lining for seismic analysis of the TBM tunnel, and the tunnel's behavioral characteristics were analyzed after numerical analysis using nonlinear models according to urban railway seismic design standards.

Pantograph-catenary Dynamic Interaction for a Overhead Line Supported by Noise Barrier

  • Belloli, Marco;Collina, Andrea;Pizzigoni, Bruno
    • International Journal of Railway
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    • v.5 no.2
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    • pp.55-64
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    • 2012
  • Subject of the paper is a particular configuration of overhead line, in which noise barrier structure is used as supports of the catenary instead of standard poles. This configuration is foreseen in case the noise barrier position is in conflict with the poles location. If the catenary is supported by the noise barrier, the motion that the latter undergo due to wave pressure associated to train transit is transmitted to the overhead line, so that potentially it influences the interaction between the catenary itself and the pantograph of the passing train. The paper focuses on the influence of such peculiar configuration on the quality of the current collection of high speed pantograph, for single and double current collection. The study has been carried out first with an experimental investigation on the pressure distribution on noise barrier, both in wind tunnel and with in-field tests. Subsequently a numerical analysis of the dynamics of the barrier subjected to the wave pressure due to train transit has been carried out, and the output of such analysis has been used as input data for the simulation of the pantograph-dynamic interaction at different speeds and with front or rear pantograph in operation. Consideration of structural modifications was then highlighted, in order to reduce the influence on the contact loss percentage.

NUMERICAL STUDY WITH VENT SHAFT POSITION IN UNDERGROUND STATION (대심도 지하정거장에서 수직구 위치에 따른 수치적 연구)

  • Oh, Hyun-Joo;Shin, Dea-Yong;Lee, Sang-Gun;Kim, Dong-Hyun;Kim, Charn-Jung
    • Journal of computational fluids engineering
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    • v.17 no.1
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    • pp.36-43
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    • 2012
  • When a high-speed train passes an underground station, large pressure waves are generated due to the piston effect. These pressure waves can cause the problems of vibration and noise as well as the ear discomfort of passengers at the underground station. This work numerically analyzed the pressure wave generation and propagation in an high-speed railway underground station, and the optimal location for vent shafts was studied to improve the passenger comfort by reducing the magnitude of the pressure wave and its rate of change. The evolution of pressure field in the underground station was calculated using a CFD(Computational Fluid Dynamics) software(Fluent), where the axis-symmetric two-dimensional model verified by Wu was used. And this study is applied to modelling of the underground station and the tunnel from Daegok station A-line of GTX(Great Train Express). From the result, we can have a conclusion that the role of vent shafts respectively were different according to the position in and out the underground station. Also Vent shaft in the underground station widely reduced pressure magnitude. And vent shaft out underground station reduced initial pressure peak value. Double vent shafts installed at tunnel toward station entrance and inside of the tunnel are the most efficient to reduce pressure. and pressure reduction increases according to the number of vent shaft.

Array Resolution Improving Methods for Beamforming Algorithm (빔형성방법에서의 분해능 향상 기법에 관한 연구)

  • Hwang, Seon-Gil;Rhee, Wook;Choi, Jong-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.164-169
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    • 2005
  • Microphone array techniques are being used widely in wind tunnel measurements for identification of the distributed aerodynamic noise sources on the model being tested. Depending on the frequencies and sound levels, conventional beamforming algorithm has limitation in separating two adjacent sources. Several modifications to the classical beamforming have been developed to enhance way resolution and reduce sidelobe levels. In this Paper the robust adaptive beamforming and the CLEAN algorithm are used to compare to the result of conventional beamforming method. It is found that the CLEAN algorithm is capable of pin-pointing locations of multiple sources nearby, while these sources are unidentifiable with robust adaptive or conventional beamforming techniques.

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Experimental Study on the Control for a Randomly Disturbing Dynamic System (불규칙한 교란을 받는 동적 시스템의 제어에 관한 실험적 연구)

  • Lee, Jong-Bok;Cho, Yun-Hyun;Yang, In-Beom;Park, Sung-Man;Heo, Hoon
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1120-1125
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    • 2007
  • Experimental study on the control of randomly disturbing system is conducted. External and internal disturbances are imposed to the system in combined manner. A vertical propeller system exposed horizontal weak turbulent air flow is chosen as an experimental model. The aim of the control system is to maintain the angular position of vertical propeller in parallel to air flow. Trajectory Tracking Stochastic Controller (TTSC) is designed to ensure system's stability while following system command. The Trajectory Tracking Stochastic Controller is composed of two controller, one is stochastic controller to suppress internal random noise and the other one is trajectory-tracking controller to follow the command having random noise. The proposed hybrid controller, TTSC, shows remarkable performance in pitch control of vertical propeller system in wind-tunnel test

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Theoretical and Experimental Study on Airfoil Singing (날개 명음소음에 관한 이론 및 실험 연구)

  • Ahn, Byoung-Kwon;Kim, Jong-Hyun;Choi, Jong-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.04a
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    • pp.476-476
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    • 2009
  • Periodic vortex separations generate periodic vertical forces acting on a trailing edge of an airfoil. When a natural frequency of the trailing edge of the airfoil is close to a vortex shedding frequency, an amplitude of the edge oscillation becomes maximal; it makes intensive noise called singing. Motion of the trailing edge may also feedback to the vortex shedding so that self-sustained oscillation appear, and a resonant frequency is locked in some interval of the speed of the incident flow. In this study, a theoretical model is proposed and applied for modeling an airfoil singing. Results are compared with experimental measurements which are carried out in an anechoic wind tunnel.

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Wall Pressure Fluctuations of the Boundary Layer Flow at the Nose of and Axisymmetric Body (축대칭 물체 선단에서 발생하는 경계층 내 벽면 변동 압력에 관한 연구)

  • 신구균;홍진숙;김상윤;김상렬;박규철
    • Journal of KSNVE
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    • v.10 no.4
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    • pp.602-609
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    • 2000
  • When an axisymmetric body moves through air the boundary layer near the stagnation region remains laminar and subsequently it goes through transition to turbulent. The experimental investigation described in this paper concerns the characteristics of wall pressure fluctuations at the initial stage of boundary layer flow including transition. Flush-mounted microphones are used to measure the wall pressure fluctuations at the transition and turbulent boundary layer region of a blunt axisymmetric body in the low noise wind tunnel. It if found from this study that the wall pressure fluctuations in the transition region is higher than that in the turbulent region.

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The Design of Low-Noise, Low-Turbulence Acoustic Wind Tunnel (저 소음, 저 난류 강도를 갖는 음향풍동의 설계)

  • 전완호;차희범;이덕주
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1995.04a
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    • pp.298-304
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    • 1995
  • 유동이 있는 경우 발생하는 소음에 대한 실험적 연구는 풍동과 무향실이 결합된 음향풍동에서 수행될 수 있다. 이러한 음향풍동은 팬, 수축부, 수집부, 확산부 그리고 무향실에 주의해서 설계되어야 하고 특히 각 부분에서 발생할 수 있는 이차소음을 최소화하도록 설계되어야 한다. 최종적으로 소음기와 흡음재를 이용해서 팬소음과 이차소음의 전파를 줄인다. 본 음향풍동은 개방형 흡입식(open suction type)으로 시험부에서 유속 62.8m/s, 난류강도 0.1%이하, 배경소음 50-55dB 이하로 설계되었다. 이러한 조건을 만족시키기 위하여 하니콤과 6장의 스크린이 있는 정체실과, 21:1의 수축비를 갖는 수축부를 이용하여 난류강도를 낮추고, 흡음재와 90도 각도의 모서리 그리고 공명형과 소산형 소음기로 소음의 전파를 줄였다.

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