Journal articles: 'Quiet Tunnels'

1

Schneider, Steven P. "Development of Hypersonic Quiet Tunnels." Journal of Spacecraft and Rockets 45, no. 4 (July 2008): 641–64. http://dx.doi.org/10.2514/1.34489.

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Liang, Zhengzhao, Xiangxin Liu, Yanbo Zhang, and Chunan Tang. "Analysis of Precursors Prior to Rock Burst in Granite Tunnel Using Acoustic Emission and Far Infrared Monitoring." Mathematical Problems in Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/214340.

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To understand the physical mechanism of the anomalous behaviors observed prior to rock burst, the acoustic emission (AE) and far infrared (FIR) techniques were applied to monitor the progressive failure of a rock tunnel model subjected to biaxial stresses. Images of fracturing process, temperature changes of the tunnel, and spatiotemporal serials of acoustic emission were simultaneously recorded during deformation of the model. Theb-value derived from the amplitude distribution data of AE was calculated to predict the tunnel rock burst. The results showed that the vertical stress enhanced the stability of the tunnel, and the tunnels with higher confining pressure demonstrated a more abrupt and strong rock burst. Abnormal temperature changes around the wall were observed prior to the rock burst of the tunnel. Analysis of the AE events showed that a sudden drop and then a quiet period could be considered as the precursors to forecast the rock burst hazard. Statistical analysis indicated that rock fragment spalling occurred earlier than the abnormal temperature changes, and the abnormal temperature occurred earlier than the descent of the AEb-value. The analysis indicated that the temperature changes were more sensitive than the AEb-value changes to predict the tunnel rock bursts.

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Quinn, Daniel B., Anthony Watts, Tony Nagle, and David Lentink. "A new low-turbulence wind tunnel for animal and small vehicle flight experiments." Royal Society Open Science 4, no. 3 (March 2017): 160960. http://dx.doi.org/10.1098/rsos.160960.

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Our understanding of animal flight benefits greatly from specialized wind tunnels designed for flying animals. Existing facilities can simulate laminar flow during straight, ascending and descending flight, as well as at different altitudes. However, the atmosphere in which animals fly is even more complex. Flow can be laminar and quiet at high altitudes but highly turbulent near the ground, and gusts can rapidly change wind speed. To study flight in both laminar and turbulent environments, a multi-purpose wind tunnel for studying animal and small vehicle flight was built at Stanford University. The tunnel is closed-circuit and can produce airspeeds up to 50 m s −1 in a rectangular test section that is 1.0 m wide, 0.82 m tall and 1.73 m long. Seamless honeycomb and screens in the airline together with a carefully designed contraction reduce centreline turbulence intensities to less than or equal to 0.030% at all operating speeds. A large diameter fan and specialized acoustic treatment allow the tunnel to operate at low noise levels of 76.4 dB at 20 m s −1 . To simulate high turbulence, an active turbulence grid can increase turbulence intensities up to 45%. Finally, an open jet configuration enables stereo high-speed fluoroscopy for studying musculoskeletal control in turbulent flow.

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Schneider, Steven P. "Developing mechanism-based methods for estimating hypersonic boundary-layer transition in flight: The role of quiet tunnels." Progress in Aerospace Sciences 72 (January 2015): 17–29. http://dx.doi.org/10.1016/j.paerosci.2014.09.008.

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Ghoreyshi, M., A. D. H. Kim, A. Jirasek, A. J. Lofthouse, and R. M. Cummings. "Validation of CFD simulations for X-31 wind-tunnel models." Aeronautical Journal 119, no. 1214 (April 2015): 479–500. http://dx.doi.org/10.1017/s0001924000010575.

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AbstractComputational Fluid Dynamics (CFD) has become an attractive method of choice in the design of many aerospace vehicles because of advances in numerical algorithms and convergence acceleration methods. However, the flow around an advanced fighter aircraft is complicated and usually unsteady due to the presence of vortex-dominated flows. The accuracy and predictability of conventional turbulence models for these applications may be questionable and therefore results obtained from these models must be validated and evaluated on the basis of experimental data from wind tunnels and/or flight tests. This work aims to validate CFD simulations of X-31 wind-tunnel models with and without a belly-mounted sting. The sting setup facilitates forced sinusoidal oscillations in one of three modes of: pitch, yaw, and roll. However, the results show that measured aerodynamic data are altered by the turbulent wake behind the sting, even at small angles of attack. The high angle-of-attack flow around the X-31 is also very complicated and unsteady due to canard and wing vortices. Therefore, validation of CFD models for predicting these complex flows can be a very challenging task. The X-31 wind-tunnel experiments were carried out in the German Dutch low-speed wind tunnel at Braunschweig and include aerodynamic force and moment measurement as well as span-wise pressure distributions at locations of 60% and 70% chord length. This data set is used to validate the Cobalt and Kestrel flow solvers and the results are similar and match quiet well with experiments for small to moderate angles of attack. The main discrepancies between CFD and measurements occur close to the wing tip, where leading-edge flaps are located.

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Hasan, Mohammed Munif, and Shabudin Mat. "Data Reduction Analysis on UTM-LST External Balance." International Journal for Research in Applied Science and Engineering Technology 10, no. 10 (October 31, 2022): 952–59. http://dx.doi.org/10.22214/ijraset.2022.47097.

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Abstract: The effective use of wind-tunnel testing in determining aerodynamic properties of a body is very much dependent upon the reliability and speed with which wind-tunnel data can be reduced. The operating efficiency of the wind tunnels is substantially improved by the capability of providing lower aerodynamic coefficients in real time, or online, which decreases the expensive wind-tunnel time necessary for each test. This paper describes a system for presenting reduced wind-tunnel data in real time for UTM-LST. The requirements for data-handling equipment and data reduction procedures for wind tunnels are quite diverse, and depend upon the wind tunnel design and the type of tests for which they are used. The supersonic wind tunnels mentioned in this description have a variety of force-balance systems and are used for force tests, pressure tests, and other research projects. Consequently, the problems associated with in order to solve this diversity we build a computerized program where we can find the transformation of axis and aerodynamic characteristics at ease. This program can find the values of different aerodynamic coefficients with certain angle of attacks.

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Liu, Tong, Yujian Zhong, Zhihua Feng, Wei Xu, Feiting Song, and Chenghan Li. "New Construction Technology of a Shallow Tunnel in Boulder-Cobble Mixed Grounds." Advances in Civil Engineering 2020 (March 21, 2020): 1–20. http://dx.doi.org/10.1155/2020/5686042.

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As a typical granular bulk medium, problems are common in boulder-cobble mixed grounds, such as easy collapse and instability and difficult effective support for large-section tunnel excavation. Tunnels constructed in BCM grounds are rare still, and there is a big gap between the design and construction of tunnels. Based on the Nianggaicun highway tunnel crossing the BCM grounds, the construction technology of tunnel in BCM grounds is studied by means of literature investigation and field survey. Here are the main conclusions: the overall deformation of surrounding rock is quite small; the pressure distribution of surrounding rock is small and loose pressure is dominant, and the safety reserve of secondary lining is large. The deformation process of surrounding rock concentrates on the construction stage. During the construction process, there are many problems, such as serious overexcavation, difficulty of bolt penetration, and continuous rock fall. In this paper, a three-bench complementary cyclic excavation method is proposed, which replaces the original CD and CRD methods. Meanwhile, the supporting system is optimized. The results show that the disturbance of surrounding rock is reduced, while the safety of construction process and the reliability of structure are increased. The new excavation method and optimized supporting system are expected to fill the gap between design and construction of tunnel in BCM grounds and provide reference for construction of such tunnels in the future.

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Duan, Xu, Qi Dong, and Wanjun Ye. "Experimental Study on Seismic Performance of Prefabricated Utility Tunnel." Advances in Civil Engineering 2019 (October 27, 2019): 1–14. http://dx.doi.org/10.1155/2019/8968260.

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Utility tunnel is a kind of underground tunnel structure that carries more than two types of public utility lines, and the utility tunnels built by the prefabricated method have been adopted in many modern cities due to their easy maintenance and environmental protection capabilities. However, knowledge about the seismic performance of the prefabricated utility tunnel and pipelines inside is quite limited. In this paper, a prefabricated utility tunnel newly built in Xi’an, China, is taken as the prototype; a series of shaking table tests are conducted to investigate the seismic performance of the prefabricated utility tunnel in loess foundation, using El Centro earthquake wave as the input loading. Details of the experimental setup focus on the design of the soil container, scaled model (1 : 10), sensor arrangement, and test cases. Dynamic responses including evaluation of boundary effect, the amplification factor of the ground and structure, distribution of soil pressure, characteristics of predominant frequencies, and the damage phenomena are analyzed. Dynamic strain obtained by Fiber Bragg Grating sensors releases the critical positions of the prefabricated utility tunnel during the earthquake. Moreover, the dynamic responses of the pipelines contained in the utility tunnel are also analyzed. From aforementioned results, the seismic performance of the prefabricated utility tunnel has been revealed. The results will provide a reference for the seismic design of prefabricated utility tunnels.

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9

Khan, Babar, Syed Muhammad Jamil, Jung Joo Kim, Turab H. Jafri, and Jonguk Kim. "Rock Mass Behavior under Tunnel Widening in Asymmetric and Symmetric Modes Considering Different Shapes and Parametric Conditions." Geosciences 9, no. 12 (December 16, 2019): 518. http://dx.doi.org/10.3390/geosciences9120518.

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To accommodate traffic volume on roads due to ever-increasing population growth, the widening of highways and motorways is in high demand. Nevertheless, the widening of tunnels on these road networks is quite complex due to the presence of numerous rock types, in situ stress, and different widening modes. To overcome these complexities, eight different tunnel shapes were simulated under varying support conditions for asymmetric and symmetric widening. It was found that the tunnels with a round shape, such as horseshoe and semicircular with flatbed, are more effective for asymmetric widening, whereas the provision of a rounded invert in these shapes can reverse the widening option to symmetric. Furthermore, an insignificant effect of the difference in asymmetric and symmetric widening of regular tunnel shapes, such as box, rectangular, and semi-elliptical, was found. A full factorial design statistical analysis confirmed the decrease in tunnel deformation by using various tunnel support systems and showed a significant deformation difference according to monitoring locations at the tunnel periphery. The deformation difference in the case of both tunnel widening modes was also analyzed according to different design parameters. This study provides a comprehensive understanding of rock mass behavior when the widening of any underground opening is carried out.

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10

Blanchard, Alan E., Jason T. Lachowicz, and Stephen P. Wilkinson. "NASA Langley Mach 6 Quiet Wind-Tunnel Performance." AIAA Journal 35, no. 1 (January 1997): 23–28. http://dx.doi.org/10.2514/2.82.

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Blanchard, Alan E., Jason T. Lachowicz, and Stephen Wilkinson. "NASA Langley Mach 6 quiet wind-tunnel performance." AIAA Journal 35 (January 1997): 23–28. http://dx.doi.org/10.2514/3.13459.

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12

Wang, Meiqian, Wei Xu, Hongyuan Mu, Jian Mi, Yonghong Wu, and Yangxing Wang. "Study on Construction and Reinforcement Technology of Dolomite Sanding Tunnel." Sustainability 14, no. 15 (July 27, 2022): 9217. http://dx.doi.org/10.3390/su14159217.

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The No. 2 conduit of the Xiaopu Tunnel in the Yuxi section of central Yunnan’s water diversion project is taken as the research object, starting from the geological conditions along with the characteristics, formation mechanism and evolutionary model of dolomite sanding. This paper discusses the engineering problems of the project’s tunnels with dolomite sanding in the water-rich section, and its corresponding engineering reinforcement plan. It was found that in the tunnel section with normal level of dolomite sanding, there was no water seepage, where measures such as advanced small conduit, mechanical excavation, short grubbing and strong support could all be adopted for safe passage. Even in the water seepage section of the weak dolomite sanding tunnel, the surrounding rock was found in close interlock with strong self-stability. The excavation and support were implemented according to the category of normal surrounding rock. In the water-rich sections with strong and intense dolomite sanding, gushing of water and sand were quite frequent, with developed fissures, broken rock masses and rich waters. During the engineering operation, phosphoric acid and sodium silicate slurry in addition to urea formaldehyde resin and oxalic acid slurry plus Malisan and liquid catalyst slurry were first prepared for water plugging. Then, pure water slurry was used for surrounding rock reinforcement, which exerted an excellent effect. This method can provide reference for reinforcing tunnels of sandy dolomite in other areas of projects.

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13

Wang, Kai, Meiyan Guo, Qingxia Xiao, Chuanyi Ma, Lingli Zhang, Xinji Xu, Ming Li, and Ningbo Li. "Frequency Domain Full Waveform Inversion Method of Acquiring Rock Wave Velocity in Front of Tunnels." Applied Sciences 11, no. 14 (July 8, 2021): 6330. http://dx.doi.org/10.3390/app11146330.

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Ahead geological prospecting, which can estimate adverse geology ahead of the tunnel face, is necessary in the process of tunnel construction. Due to its long detection range and good recognition effect on the interface, the seismic method is widely used in tunnel ahead prospecting. However, the observation space in tunnels is quite narrow compared to ground seismic prospecting, which leads to some problems in the acquisition of wave velocity, including: the velocity of the direct wave is used to replace the wave velocity of the forward rock approximately; the arrival time information of seismic waves is the main factor in time-travel inversion or the tomography method, which is sufficient to provide a simple model rather than deal with complex geological conditions. In view of the above problems, the frequency domain full waveform inversion method in ground prospecting is introduced to tunnel seismic prospecting. In addition, the optimized difference format is given according to the particularity of the tunnel environment. In this method, the kinematics and dynamics of the seismic wavefield are fully used to obtain more accurate wave velocity results. Simultaneously, forward modeling and inversion simulations on tunnel samples with typical adverse geological bodies are given here, which verified the validity and reliability of the proposed method.

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Krajček Nikolić, Karolina, Anita Domitrović, and Slobodan Janković. "Estimation of Aerodynamic Coefficients in a Small Subsonic Wind Tunnel." PROMET - Traffic&Transportation 30, no. 4 (September 10, 2018): 457–63. http://dx.doi.org/10.7307/ptt.v30i4.2685.

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To apply the experimental data measured in a wind tunnel for a scaled aircraft to a free-flying model, conditions of dynamical similarity must be met or scaling procedures introduced. The scaling methods should correct the wind tunnel data regarding model support, wall interference, and lower Reynolds number. To include the necessary corrections, the current scaling techniques use computational fluid dynamics (CFD) in combination with measurements in cryogenic wind tunnels. There are a few methods that enable preliminary calculations of typical corrections considering specific measurement conditions and volume limitation of test section. The purpose of this paper is to present one possible approach to estimating corrections due to sting interference and difference in Reynolds number between the real airplane in cruise regime and its 1:100 model in the small wind tunnel AT-1. The analysis gives results for correction of axial and normal force coefficients. The results of this analysis indicate that the Reynolds number effects and the problem of installation of internal force balance are quite large. Therefore, the wind tunnel AT-1 has limited usage for aerodynamic coefficient determination of transport airplanes, like Dash 8 Q400 analyzed in this paper.

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Tao, Xiang-Ling, Yun-He Su, Qi-Yin Zhu, and Wen-Long Wang. "Pasternak Model-Based Tunnel Segment Uplift Model of Subway Shield Tunnel during Construction." Advances in Civil Engineering 2021 (September 9, 2021): 1–10. http://dx.doi.org/10.1155/2021/8587602.

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Segment uplift is a frequent problem during the construction of shield tunnels. The phenomenon of segment uplift in Xuzhou Metro Line 1 is investigated. The segment uplift magnitude in the shale layer is quite smaller than that in the clay layer. A tunnel segment uplift calculation model based on the Pasternak foundation beam model is proposed, which considers the hardening process of the grouted body with time. The finite difference method is adopted to calculate the magnitude of segment uplift during different tunnel construction stages, and a numerical solution of segment uplift on the longitudinal direction is obtained. The applicability of the numerical solution is studied by comparing with the field test results and parametric analyses are also performed to investigate the eﬀects of diﬀerent factors on segment uplifting. The results show that the coefficient of subgrade modulus, shear stiffness of the shear layer, and grout pressure all influence the segment uplifting of the tunnel. The influence of the coefficient of subgrade modulus and grout pressure on segment uplift is more significant.

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Lakebrink, Matthew T., Kevin G. Bowcutt, Troy Winfree, Christopher C. Huffman, and Thomas J. Juliano. "Optimization of a Mach-6 Quiet Wind-Tunnel Nozzle." Journal of Spacecraft and Rockets 55, no. 2 (March 2018): 315–21. http://dx.doi.org/10.2514/1.a33794.

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Juliano, Thomas J., Matthew P. Borg, and Steven P. Schneider. "Quiet Tunnel Measurements of HIFiRE-5 Boundary-Layer Transition." AIAA Journal 53, no. 4 (April 2015): 832–46. http://dx.doi.org/10.2514/1.j053189.

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Lachowicz, Jason T., Ndaona Chokani, and Stephen P. Wilkinson. "Boundary-layer stability measurements in a hypersonic quiet tunnel." AIAA Journal 34, no. 12 (December 1996): 2496–500. http://dx.doi.org/10.2514/3.13430.

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Ouyang, Zhiyong, Peijie Li, Jie Cui, Ruofan Luo, and Dandan Yuan. "Shaking Table Test Study on Flexible and Rigid Immersed Tube Tunnel in Liquefiable Soil Layer." Mathematical Problems in Engineering 2020 (August 27, 2020): 1–16. http://dx.doi.org/10.1155/2020/4980549.

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To study the seismic response law of the immersed tunnel under different structural stiffnesses, three groups of shaking table models of immersed tunnel are carried out, including free-field model, flexible tunnel model, and rigid tunnel model. The similarities and differences of the pore water pressure and acceleration time-history between the free site and liquefiable soil layer around the flexible and rigid immersed tube tunnel are analyzed. The results show that, compared with the soil layer at the same position in the free-field, both the amplitude of acceleration and frequency component in the surrounding soil layer are affected by the stiffness of tunnel, and the influence comes greater with the larger stiffness of tunnel. When the input amplitude of seismic ground motion is small, the soil layer in the free field and the flexible tunnels share the same acceleration amplification law. The development law of pore pressure in the soil layer of test 1 was similar to test 2 but was quite different from test 3. Specifically, when the tunnel stiffness is smaller, the surrounding soil layer is easier to liquefy, with greater influence of the tunnel stiffness on the development law of pore pressure in the surrounding soil layer. The lower the soil buried depth is, the faster the pore pressure dissipates. The growth rate of tunnel strain is related to the stiffness of the structure. Generally speaking, the strain growth rate of the structure with smaller stiffness is higher under moderate earthquakes. The smaller the tunnel stiffness is, the more adaptable the tunnel is to the movement of the surrounding soil layer.

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Junaidin, Buyung, Anggraeni Kusumaningrum, Wisnu Prayogih, and Yosep Reo. "Rancang Bangun Sensor Kecepatan Angin Berbasis Arduino untuk Terowongan Angin Low Subsonic." AVITEC 4, no. 2 (August 2, 2022): 187. http://dx.doi.org/10.28989/avitec.v4i2.1295.

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The wind speed gauge in a wind tunnel plays an important role in the airflow simulation process so that it is similar to the actual conditions as desired. Wind speed measurement in wind tunnel mostly use manometer with special fluid (red manometer fluid) and the resulting data is in the form of analog data. The red manometer fluid is unavailable in Indonesia and its price is quite expensive so it becomes a challenge for wind tunnels that still use manometer. Therefore, it is necessary to make a new instrument for measuring wind speed that is easy to use by utilizing materials that are easily obtained but still apply the same measurement principles as a manometer in measuring wind speed in wind tunnels. The design of the wind speed measuring device can take advantage of microcontroller technology. The wind speed sensor design process goes through three stages including hardware design, software design, and system design. The hardware used for the system are an Arduino Uno R3 microcontroller, a differential pressure sensor MPXV7002DP, and an LCD. Research results obtain a wind speed sensor that can be used to measure wind speed in a low subsonic wind tunnel based on Bernoulli's principle that utilizes a pitot tube with a maximum speed of 30m/s. The wind speed sensor is an Arduino-based design that can display the wind speed measurement results on the LCD screen. The wind speed sensor was declared valid to be used to measure wind speed because there were no deviations from the wind speed measurement when compared to the measurement results from a calibrated anemometer.

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Peña-García, Antonio, and Thi Nguyen. "A Global Perspective for Sustainable Highway Tunnel Lighting Regulations: Greater Road Safety with a Lower Environmental Impact." International Journal of Environmental Research and Public Health 15, no. 12 (November 27, 2018): 2658. http://dx.doi.org/10.3390/ijerph15122658.

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Tunnel lighting installations function 24 h a day, 365 days a year. These infrastructures have increased exponentially and now connect quite distant locations, even on different continents. This has led European administrations and international regulatory bodies to establish regulations for tunnel safety with the lowest environmental impact. However, until now, these regulations have almost exclusively focused on traffic safety, and relegated sustainability to the background. Even though they recognize the need to reduce energy consumption, they do not propose any tools for doing so. Given the impact of these installations and the lack of a specific regulatory framework, Asian countries will soon be forced either to update previous standards for tunnel lighting or elaborate new ones. A better understanding of the weaknesses of European regulations combined with a willingness to embrace innovation could position Asia as a world leader in the regulation of more sustainable road tunnels. The objective of this research was to improve the sustainability of tunnel lighting installations through new regulations or amendments to existing ones, without impairing the mental well-being of users, who could potentially be affected by energy-saving measures. Accordingly, this paper presents and analyzes a broad proposal for formulating tunnel lighting regulations. The originality of this proposal lies in the fact that it integrates road safety, lower environmental impact, and user well-being. Furthermore, it is expected to broaden the perspective of regulatory bodies and public administrations with regard to tunnel installations, which would ultimately enhance their sustainability.

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Pastushkov, G. P., and M. A. Kisel. "PREPARATORY STAGE FOR MONITORING THE LOAD-BEARING STRUCTURES OF THE OPERATED SUBWAY STATION." ACADEMIC JOURNAL Series: Industrial Machine Building, Civil Engineering 2, no. 49 (October 17, 2017): 116–25. http://dx.doi.org/10.26906/znp.2017.49.832.

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Modern technologies for the construction of a subway underground allow reconstruction of operated stations without stopping the movement of trains and subway disruptions. However, this problem is quite complicated, because at the device of transitive tunnels it is possible to violate the stress-strain state of the main load-bearing structures and ground of the station base, track upper-structure drawdown appearance that is impermissible for the safe operation of the subway. The article presents the results of the preparatory stage of theMinsk subway station main load-carrying structures state monitoring, as well as the results of spatial calculations based on design data, considering the stage of transition tunnel construction work from the first to the third branches.

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Branch, Philip. "Measurements and Models of 915 MHz LoRa Radio Propagation in an Underground Gold Mine." Sensors 22, no. 22 (November 9, 2022): 8653. http://dx.doi.org/10.3390/s22228653.

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Underground mining increasingly relies on wireless communications for its operations. The move to automating many underground mining processes makes an understanding of the propagation characteristics of key wireless technologies underground a topic of considerable importance. LoRa has great potential for communications in underground mines, but data on its propagation are quite scarce. In this paper, we describe our measurements of LoRa radio propagation in an underground gold mine. We took measurements in an extraction tunnel with line of sight and in extraction and access tunnels without line of sight. We observed excellent propagation, both with and without line of sight. Our observations support claims by others that the steel-lined tunnels act as a waveguide. As well as reporting measurements, we also developed models of propagation. For line of sight, we show that pathloss is well modelled by a power law with pathloss index of 1.25 and that variability of signal strength is well modelled by a lognormal distribution. We also successfully modelled propagation without line of sight over short distances using a Fresnel Diffraction and Free Space model.

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Manning, Melissa L., and Ndaona Chokani. "Computational Evaluation of Quiet Tunnel Hypersonic Boundary-Layer Stability Experiments." Journal of Spacecraft and Rockets 41, no. 3 (May 2004): 406–15. http://dx.doi.org/10.2514/1.10698.

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UGAI, Yoshio, Yoshiyuki MARUTA, and Shoji SUZUKI. "The development of the quiet flow wind tunnel for aeroacoustics." Transactions of the Japan Society of Mechanical Engineers Series B 53, no. 487 (1987): 928–32. http://dx.doi.org/10.1299/kikaib.53.928.

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Lu, Liangliang, Xinjiang Wei, Xiao Wang, Zihai Yan, Zeyu Cheng, and Haoyan Hu. "Mechanical Behavior of the Special Segment Structure during Upward Shield Tunnel Construction." Mathematical Problems in Engineering 2022 (August 3, 2022): 1–14. http://dx.doi.org/10.1155/2022/8587689.

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The upward shield method in horizontal tunnels has the advantages of small ground space occupation, low construction cost, and short construction period, which expresses substantial economic benefits. The special segments of horizontal shield tunnels corresponding to the upward shield method construction area have special design requirements, and different internal force calculations and analyses should be carried out. To determine the mechanical behavior of the special segment structure of horizontal shield tunnels during the construction of upward shield tunnels, the theoretical calculation formula of the internal force of the special segment structure is deduced based on the average uniform rigidity ring method. Moreover, the bending moment and axial force of special segments are numerically simulated and analyzed using Midas GTS NX software. Finally, the theoretical formula and finite element calculation results are compared and analyzed. The results show that the internal force values of the open segment ring and the adjacent segment ring of the special segment are quite different during upward shield tunnel construction. Furthermore, compared with the arch crown and arch bottom of the segment ring, the stress at the arch waist of the segment ring is the most unfavorable. The stress difference between the open segment ring and the adjacent segment ring may cause unbalanced deformation, leading to damage to the segment ring radial joint. In the design and construction, attention should be given to the shear strength of the segment ring radial joint and the bending stiffness of the ring joint at the arch waist.

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Wang, Jinquan, Juntong An, Shenyi Zhang, Ruoyu Ge, Qiwu Xie, Qingshu Chen, Sizhuo Zheng, and Mingge Ye. "Numerical Investigation and Prediction of Side-By-Side Tunneling Effects on Buried Pipelines." Sustainability 15, no. 1 (December 26, 2022): 353. http://dx.doi.org/10.3390/su15010353.

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With the fast development of underground space engineering, it is inevitable for buried pipelines to be crossed by twin tunnels. Previous studies mainly focused on the single-tunneling effects on pipelines. To emphasize the twin-tunneling effects on buried pipelines, we first examined the effectiveness of the ground settlement prediction method under twin-tunneling conditions. Then, the estimated ground settlement boundary condition was applied to the beam-on-spring finite element model. The numerical results show that with the decrease in tunnel depth and twin tunnel space, the values and positions of the maximum ground settlement and longitudinal pipe bending behavior both changed significantly. The biased distance of the maximum settlement position and the distance to the inflection point of the final ground settlement curve can be obtained by curve fitting. Based on that, a semi-empirical prediction method for the longitudinal pipe bending strain was proposed. The predicted values matched quite well with the numerical results, which can thus provide a quick and effective structural safety and integrity assessment approach for buried pipelines subjected to twin-tunneling conditions.

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Demagh, Rafik, and Fabrice Emeriault. "3D MODELLING OF TUNNEL EXCAVATION USING PRESSURIZED TUNNEL BORING MACHINE IN OVERCONSOLIDATED SOILS." Studia Geotechnica et Mechanica 35, no. 2 (June 1, 2013): 3–17. http://dx.doi.org/10.2478/sgem-2013-0020.

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Abstract The construction of shallow tunnels in urban areas requires a prior assessment of their effects on the existing structures. In the case of shield tunnel boring machines (TBM), the various construction stages carried out constitute a highly three-dimensional problem of soil/structure interaction and are not easy to represent in a complete numerical simulation. Consequently, the tunnelling- induced soil movements are quite difficult to evaluate. A 3D simulation procedure, using a finite differences code, namely FLAC3D, taking into account, in an explicit manner, the main sources of movements in the soil mass is proposed in this paper. It is illustrated by the particular case of Toulouse Subway Line B for which experimental data are available and where the soil is saturated and highly overconsolidated. A comparison made between the numerical simulation results and the insitu measurements shows that the 3D procedure of simulation proposed is relevant, in particular regarding the adopted representation of the different operations performed by the tunnel boring machine (excavation, confining pressure, shield advancement, installation of the tunnel lining, grouting of the annular void, etc). Furthermore, a parametric study enabled a better understanding of the singular behaviour origin observed on the ground surface and within the solid soil mass, till now not mentioned in the literature.

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SAWADA, Hideo. "STATUS OF IMPROVING NAL 0.2M SUPERSONIC WIND TUNNEL FOR QUIET FLOW." Wind Engineers, JAWE 1999, no. 78 (1999): 69–72. http://dx.doi.org/10.5359/jawe.1999.69.

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MARUTA, Yoshiyuki, and Takashi TAKEMURA. "Experiments for aerodynamic noise by using the Quiet Flow Wind Tunnel." Journal of the Visualization Society of Japan 12, no. 1Supplement (1992): 91–94. http://dx.doi.org/10.3154/jvs.12.1supplement_91.

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MARUTA, Yoshiyuki, Byungjin AN, Hiroyuki OGOSE, Motohiko NOHMI, Masashi OBUCHI, and Takeshi TOI. "Quiet Down the Air-flow Self Noise in Acoustic Wind Tunnel." Proceedings of the Symposium on Environmental Engineering 2018.28 (2018): 114. http://dx.doi.org/10.1299/jsmeenv.2018.28.114.

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Zhu, Fu-guang, Dong-sheng Xu, Rui-shan Tan, Bin Peng, He Huang, and Zhuo-wen Liu. "Development of Optic-Electric Hybrid Sensors for the Real-Time Intelligent Monitoring of Subway Tunnels." Journal of Sensors 2021 (July 12, 2021): 1–10. http://dx.doi.org/10.1155/2021/8871893.

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The settlement and deformation monitoring of subway tunnels had difficult in long-distance and real time measurement. This study proposed an optic-electric hybrid sensor based on infrared laser ranging technology and cable-sensing technology. The working principle, hardware layer, design details, laboratory calibration and field validation were presented and discussed. The optic-electric hybrid sensor implemented the real-time intelligent analysis modulus for the whole system which could analysis the measurement errors and improve the accuracy. The laboratory calibration tests were carried out and the results shown that the hybrid sensors had measurement resolution of 1 mm with the maximum measurement range of 100 m. A remote real-time intelligent monitoring system is established based on the hybrid sensors. The system contains an edge computing module, real-time communication module and warning light signal with three colors. The stability of data acquisition and transmission of the intelligent control monitoring system under long-term conditions was examined. Test results shown that the system was quite stable for the long-term measurement. The whole system was verified in a constructing subway tunnel of Wuhan Metro Line 8, China. According to the field monitoring results, the deformations and the state of health safety of the tunnel was evaluated. The results of this study could provide useful guidance for tunnel deformation monitoring and has great practical value in civil engineering.

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Rehman, Zahid Ur, Sajjad Hussain, Muhammad Tahir, Saira Sherin, Noor Mohammad, Nasrullah Dasti, Salim Raza, and Muhammad Salman. "Numerical modelling for geotechnical assessment of rock mass behaviour and performance of support system for diversion tunnels using optimized Hoek-Brown parameters." Mining of Mineral Deposits 16, no. 1 (March 30, 2022): 1–8. http://dx.doi.org/10.33271/mining16.01.001.

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Purpose. Empirical and numerical methods play a vital role in assessing rock mass behaviour quantitatively and qualitatively to design underground structures/caverns and support systems. This research aims to assess and evaluate the rock mass be-haviour for safe, stable, efficient, and economical design of support system for underground structures especially tunnels in diverse rock mass conditions. Methods. In this research, such empirical design methods as Rock Mass Rating (RMR), Q-system and GSI were used to characterize and classify the rock mass environment along the tunnel for the preliminary design of twin tunnels and support systems. The geomechanical parameters, Hoek-Brown failure criterion, and its variants for assessing rock mass behaviour were optimized using multiple regression of Stewart, generalized and globalized variant of nonlinear regression method. The rock mass was classified for the selected section A-A. The excavation method and support system for the said section were designed based on the results obtained from empirical modelling. 2D elasto-plastic finite element method (FEM) was used for numerical analysis of rock mass behaviour and performance of the designed supports in section A-A. Findings. The major rock type encountered in the diversion scheme comprises gabbronorite (GN) and Ultramafic Association (UMA). Based on the quantification of RMR, Q-system, and GSI, section A-A’s rock mass ranges from very poor to poor. From the numerical analysis for the said rock mass environment both RMR and Q system support recommendations are equally efficient to support the rock mass surrounding the tunnel. However, keeping in view the yield zone, especially in the crown, the rock bolt’s length should not be less than 5 meters. Based on the analysis of results, both the tunnels are at a safe distance from each other. Originality. In this research, the design input parameters for numerical modeling were optimized by using different techniques to eliminate the chances of error in evaluating rock mass behaviour and designing an optimum support system in the said rock mass environment. Practical implications. The assessment of rock mass behaviour and the design of optimum support systems in heterogenous conditions is quite challenging and requires thorough investigation through different design techniques. This research provides a refined meth-od to be used for the safe, stable, and economical design of tunnels.

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Fisher, Jordan M., Brandon C. Chynoweth, Michael E. Smyser, Austin M. Webb, Mikhail N. Slipchenko, Joseph S. Jewell, Terrence R. Meyer, and Steven J. Beresh. "Femtosecond Laser Electronic Excitation Tagging Velocimetry in a Mach Six Quiet Tunnel." AIAA Journal 59, no. 2 (February 2021): 768–72. http://dx.doi.org/10.2514/1.j059879.

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Shi, Mingtao, Wenkai Zhu, and Cunbiao Lee. "Engineering Model for Transition Prediction Based on a Hypersonic Quiet Wind Tunnel." AIAA Journal 58, no. 8 (August 2020): 3476–85. http://dx.doi.org/10.2514/1.j059054.

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Han, Soohee. "Towards Efficient Implementation of an Octree for a Large 3D Point Cloud." Sensors 18, no. 12 (December 12, 2018): 4398. http://dx.doi.org/10.3390/s18124398.

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The present study introduces an efficient algorithm to construct a file-based octree for a large 3D point cloud. However, the algorithm was very slow compared with a memory-based approach, and got even worse when using a 3D point cloud scanned in longish objects like tunnels and corridors. The defects were addressed by implementing a semi-isometric octree group. The approach implements several semi-isometric octrees in a group, which tightly covers the 3D point cloud, though each octree along with its leaf node still maintains an isometric shape. The proposed approach was tested using three 3D point clouds captured in a long tunnel and a short tunnel by a terrestrial laser scanner, and in an urban area by an airborne laser scanner. The experimental results showed that the performance of the semi-isometric approach was not worse than a memory-based approach, and quite a lot better than a file-based one. Thus, it was proven that the proposed semi-isometric approach achieves a good balance between query performance and memory efficiency. In conclusion, if given enough main memory and using a moderately sized 3D point cloud, a memory-based approach is preferable. When the 3D point cloud is larger than the main memory, a file-based approach seems to be the inevitable choice, however, the semi-isometric approach is the better option.

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Liu, Tianshu, Christopher A. C. Ward, Justin Rubal, John P. Sullivan, and Steven P. Schneider. "Heat-Flux Measurements with Temperature-Sensitive Paint in a Mach-6 Quiet Tunnel." Journal of Spacecraft and Rockets 50, no. 2 (March 2013): 282–93. http://dx.doi.org/10.2514/1.a32311.

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Taskinoglu, Ezgi S., Doyle D. Knight, and Steven P. Schneider. "Computational Fluid Dynamics Evaluation of Bleed Slot of Purdue Mach 6 Quiet Tunnel." AIAA Journal 44, no. 6 (June 2006): 1360–62. http://dx.doi.org/10.2514/1.17231.

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Zheng, Q., C. L. Xin, Y. S. Shen, Z. M. Huang, and B. Gao. "Seismic Damage Prediction Method for Lining Structures Based on the SEDR Principle." Shock and Vibration 2021 (January 7, 2021): 1–13. http://dx.doi.org/10.1155/2021/6637909.

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The safety and stability of lining structures are core concerns of tunnel and underground engineering. It is crucial to determine whether a lining structure would crack and which direction the crack would expand with seismic excitation. In previous literature, the principle based on stress and strain has been widely used to predict the seismic damage of lining structures, whereas it cannot specify the cracking modes. Taking account of that deficiency, this paper introduces the strain energy density ratio (SEDR) principle and proposes a seismic damage prediction method for lining structures, which can precisely predict the crack positions and expansion directions. Moreover, numerical simulations of the typical seismic damage sections of two tunnels in the Great Wenchuan Earthquake and a calculating example of the theoretical equations are conducted to verify the proposed method. In summary, the numerical simulation results show that the arch springing cracks first, and the invert cracks next; then the cracks expand to the spandrel, and finally, they form oblique cracks, annular cracks, and longitudinal cracks, whose positions and patterns are in accordance with the field investigation results. In terms of the calculating example results, the obtained two-fold SEDR and cracking angle θ are 1.87 and −6.28°, respectively, which are consistent with the numerical simulation results. Therefore, one can see that the proposed seismic damage prediction method based on the SEDR principle is quite accurate. This method can be used to predict the seismic damage of lining structures and provide a reference for the research of the damage mechanism of tunnels.

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Zheng, Q., C. L. Xin, Y. S. Shen, Z. M. Huang, and B. Gao. "Seismic Damage Prediction Method for Lining Structures Based on the SEDR Principle." Shock and Vibration 2021 (January 7, 2021): 1–13. http://dx.doi.org/10.1155/2021/6637909.

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The safety and stability of lining structures are core concerns of tunnel and underground engineering. It is crucial to determine whether a lining structure would crack and which direction the crack would expand with seismic excitation. In previous literature, the principle based on stress and strain has been widely used to predict the seismic damage of lining structures, whereas it cannot specify the cracking modes. Taking account of that deficiency, this paper introduces the strain energy density ratio (SEDR) principle and proposes a seismic damage prediction method for lining structures, which can precisely predict the crack positions and expansion directions. Moreover, numerical simulations of the typical seismic damage sections of two tunnels in the Great Wenchuan Earthquake and a calculating example of the theoretical equations are conducted to verify the proposed method. In summary, the numerical simulation results show that the arch springing cracks first, and the invert cracks next; then the cracks expand to the spandrel, and finally, they form oblique cracks, annular cracks, and longitudinal cracks, whose positions and patterns are in accordance with the field investigation results. In terms of the calculating example results, the obtained two-fold SEDR and cracking angle θ are 1.87 and −6.28°, respectively, which are consistent with the numerical simulation results. Therefore, one can see that the proposed seismic damage prediction method based on the SEDR principle is quite accurate. This method can be used to predict the seismic damage of lining structures and provide a reference for the research of the damage mechanism of tunnels.

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Naiman, H., D. D. Knight, and S. P. Schneider. "Computational redesign of the test section for the Boeing/AFOSR Mach 6 Quiet Tunnel." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 223, no. 4 (April 2009): 407–13. http://dx.doi.org/10.1243/09544100jaero424.

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Wang, Shu Hong, Juan Xia Zhang, Chun An Tang, and Shan Yong Wang. "Modeling of the Effect of Excavation Mode on the Extent of the Anisotropic Zone Surrounding Deep Tunnels." Key Engineering Materials 353-358 (September 2007): 3014–17. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.3014.

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A series of numerical model tests were performed to investigate the behaviour of the anisotropic rock surrounding circular excavations under high confining pressures. The aim was to provide information on the formation of fractures and failure around deep level rock tunnels under controlled conditions. Solid cubes containing a circular hole were confined to a vertical pressure with same as the confinement in the horizontal directions. In this modeling, the inhomogeneous rock is generated by using Weibull parameters which are related to the microstructural properties determined by crack size distribution and grain size. The fracture angle is assumed to be 45o. The observed failure zone around the excavation was simulated using both the maximum tensile strain criterion and Mohr-Coulomb criterion respectively (as the damage threshold). And RFPA (Realistic Failure Process Analysis) code was used as the calculating tool in this modelling, three opening modes are simulated and compared. Computational model predictions that include crack propagation and failure modes of rock show a good agreement with those of the observation in site. It is pointed out that the damage evolution of EDZ strongly depends on the inhomogeneous, the excavation mode, anisotropic property, and the various loading conditions. Concerning the existence of a weak plane, the amount of displacement at the side wall of the tunnel was quite large, since the shear deformation occurred in EDZ. The model is implemented in RFPA code and is able to represent the change in fracture patterns between the solid and jointed parts. This provides confidence for the application of the numerical model to the design of rock tunnels at great depth.

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Li, Ke, and Han Guo. "Optimization of Tunnel Support Type through Fault Zone." Applied Mechanics and Materials 580-583 (July 2014): 1184–87. http://dx.doi.org/10.4028/www.scientific.net/amm.580-583.1184.

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The mechanical properties of tunnel surrounding rock in fault zone is usually quite weak, and the support pressure and displacement are larger than other sections, so the support type in fault zone is a critical issue for tunnel safety. Three types of tunnel support through fault zone were analyzed by finite element method (FEM): ①Reinforced concrete support, ②bolting-shotcreting and reinforced concrete support,③grouting and reinforced concrete support. The result shows that support stress and surrounding rock displacement with grouting and reinforced concrete support is quite smaller than the other support types.

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Juliano, Thomas J., Laura A. Paquin, and Matthew P. Borg. "HIFiRE-5 Boundary-Layer Transition Measured in a Mach-6 Quiet Tunnel with Infrared Thermography." AIAA Journal 57, no. 5 (May 2019): 2001–10. http://dx.doi.org/10.2514/1.j056750.

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Chapman, D. N., S. K. Ahn, and D. VL Hunt. "Investigating ground movements caused by the construction of multiple tunnels in soft ground using laboratory model tests." Canadian Geotechnical Journal 44, no. 6 (June 1, 2007): 631–43. http://dx.doi.org/10.1139/t07-018.

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The prediction of the ground movements above single tunnels in soft ground is well established and can be estimated using semi-empirical methods based on the Gaussian curve. However, the prediction of ground movements associated with closely spaced multiple tunnels, in particular side-by-side (sbs) tunnels, is not as well understood, and therefore simple predictive methods for this application are currently quite limited in terms of their accuracy. This paper describes results from a series of small-scale (1/50) laboratory model tests (conducted at 1g) carried out in Speswhite kaolin clay. These tests have been conducted to gain a greater understanding of the short-term ground movements associated with closely spaced multiple (sbs) tunnels. The observed ground movement results from these tests have shown many of the characteristics observed at full-scale in the published case studies. These results are compared to the commonly used Gaussian curve prediction method and demonstrate the potential inaccuracy in this approach for predicting ground movements associated with closely spaced multiple tunnels. A method that modifies the Gaussian curve approach is also applied to the laboratory data and shows improved predictions.Key words: tunnelling, ground movements, multiple side-by-side tunnels, physical modelling, settlement prediction.

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Tahir, Taleah, Muhammad Afzal, Malik Nadeem Azam Khan, Khalid Mehmood Raja, Wahaj, and Batool. "Cost effectiveness of tunneled double lumen to non-tunnel double lumen dialysis catheters." Professional Medical Journal 26, no. 12 (December 10, 2019): 2192–95. http://dx.doi.org/10.29309/tpmj/2019.26.12.3821.

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Objectives: To ascertain the cost-effectiveness of tunneled catheters to non-tunneled catheter in dialysis patients of a tertiary care hospital. Study Design: Retrospective cross-sectional study. Study Design: Department of Nephrology, Pak Emirates Military Hospital Rawalpindi. Period: Jan 2016 to Jan 2019. Material & Methods: The sample population comprised of 500 patients, being divided into two groups and followed over a period of 03 yrs. Group A had tunneled double lumen and group B had non tunneled double lumen. Dialysis was started on the same day in both groups. Both groups were compared in terms of cost effectiveness. Cost effectiveness included price of catheter, procedure cost, treatment of infection (if any), and change of catheter in case of catheter malfunction. The amount spent on each patient was added and then an average was calculated. Results: Out of 600 patients, 300 were in group A and 300 patients were in group B. The two groups were analogous in gender (male: 52.8% vs 57.8%, p=0.35)age (41 years vs 49 yrs, p=0.71) hypertension and diabetes as the main causes of ESRD (51% vs 39%, p=0.08 and 32% vs 34%, p=0.38, respectively). Total incurred cost of tunneled double lumen was Rs.19000.00, with average infection free patency time being three months during which Arteriovenous fistula formed. In comparison, non-tunneled double lumen in 300 patients, average cost incurred was Rs.30000.00 including cost incurred on treating sepsis and in two –three insertions in few cases . There was no procedure related mortality. Conclusion: The cost-effectiveness of Tunneled double lumen catheters and clinical benefit of reduction in patency failures and also access related infections make them the first choice for dialysis patients in majority of dialysis centers of our country but large randomized control trials needed as the sample size quite less to detect a difference from the newer agents.

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Pindado, Santiago, Javier Cubas, and Félix Sorribes-Palmer. "On the Analytical Approach to Present Engineering Problems: Photovoltaic Systems Behavior, Wind Speed Sensors Performance, and High-Speed Train Pressure Wave Effects in Tunnels." Mathematical Problems in Engineering 2015 (2015): 1–17. http://dx.doi.org/10.1155/2015/897357.

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At present, engineering problems required quite a sophisticated calculation means. However, analytical models still can prove to be a useful tool for engineers and scientists when dealing with complex physical phenomena. The mathematical models developed to analyze three different engineering problems: photovoltaic devices analysis; cup anemometer performance; and high-speed train pressure wave effects in tunnels are described. In all cases, the results are quite accurate when compared to testing measurements.

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Hofferth, Jerrod, William Saric, Joseph Kuehl, Eduardo Perez, Travis Kocian, and Helen Reed. "Boundary-layer instability and transition on a flared cone in a Mach 6 quiet wind tunnel." International Journal of Engineering Systems Modelling and Simulation 5, no. 1/2/3 (2013): 109. http://dx.doi.org/10.1504/ijesms.2013.052386.

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Benay, R., and B. Chanetz. "Design of a boundary layer suction device for a supersonic quiet wind tunnel by numerical simulation." Aerospace Science and Technology 8, no. 4 (June 2004): 255–71. http://dx.doi.org/10.1016/j.ast.2003.11.003.

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Zhang, Yang, Sijia Yu, Ling Wan, and Tingting Lin. "Processing of Underground Nuclear Magnetic Resonance Data for Underground River Detection: A Case Study in Doumo Tunnel, Guizhou, China." Journal of Environmental and Engineering Geophysics 25, no. 3 (September 2020): 315–23. http://dx.doi.org/10.32389/jeeg19-083.

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Underground nuclear magnetic resonance (NMR) is introduced to detect the risk of groundwater-induced disasters in the underground engineering such as tunnels and mines. However, underground NMR is in practice often limited to the extremely low signal-to-noise ratios (SNRs). On the one hand, small coils are necessary to be used to detect water in the narrow underground space, which decreases the amplitude of the excited signal. On the other hand, the weak signal is submerged in quite serious electromagnetic noise which is generated from the electrical installations. The low SNRs emphasize the importance of using an optimal post-processing strategy to obtain the reliable underground NMR data. The objective of this paper is to explain the processing of underground NMR data taking the detection of the underground river in Doumo Tunnel as an example. We have evaluated the noise condition in Doumo Tunnel and the noise level of 0.6760 nV/m2 was found in this area. At such a high noise level, the reliable underground NMR signal is difficult to be extracted and the credible depth profile of water content is unable to be provided. Then, we have analyzed the noise interference. Although de-spiking algorithm and reference-based noise cancellation method were applied to remove the major noise sources, the underground NMR signal is still invisible. There is still a lot of additive noise remained, so time-frequency peak filtering method is further used to suppress the remaining noise. The performance of the proposed post-processing strategy is tested on the underground NMR data from the underground river. The result was consistent with the geological structure, which is demonstrated to be able to directly provide a security pre-warning of the underground engineering.

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Journal articles on the topic 'Quiet Tunnels'

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