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Academic literature on the topic 'Quiet Tunnels'

Author: Grafiati
Published: 10 December 2022
Last updated: 29 January 2023

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Journal articles on the topic "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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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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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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Dissertations / Theses on the topic "Quiet Tunnels"

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Manning, Melissa Lynn. "COMPUTATIONAL EVALUATION OF QUIET TUNNEL HYPERSONIC BOUNDARY LAYER STABILITY EXPERIMENTS." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010112-081130.

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Manning, Melissa Lynn. Computational Evaluation of Quiet Tunnel Hypersonic Boundary Layer Stability Experiments. (Under the direction of Dr. Ndaona Chokani.) A computational evaluation of two stability experiments conducted in the NASA Langley Mach 6 axisymmetric quiet nozzle test chamber facility is conducted. Navier-Stokes analysis of the mean flow and linear stability theory analysis of boundary layer disturbances is performed in the computations. The effects of adverse pressure gradient and wall cooling are examined. Calculated pressure, temperature and boundary layer thickness distributions show very good overall agreement with experimental measurements. Computed mass flux and total temperature profiles show very good quantitative agreement with uncalibrated hot-wire measurements obtained with the hot-wire operated in high and low overheat modes respectively. Comparisons between calibrated hot-wire data and mean flow computations show excellent agreement in the early stages of the transitional flow. However, examination of the wire Reynolds number and mass flux and total temperature eigenfunction profiles suggest that when operated in high overheat mode the sensitivity of the hot-wire to total temperature is significant. Thus, while uncalibrated hot-wire measurements are useful to characterize the overall features of the flow, calibrated hot-wire measurements are necessary for quantitative comparison with stability theory. Computations show that adverse pressure gradient and wall cooling decrease the boundary layer thickness and increase the frequency and amplification rate of the unstable second mode disturbances; these findings are consistent with the experimental observations.

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Naiman, Hadassah. "Analysis and design of quiet hypersonic wind tunnels." 2010. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.000052138.

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(7399604), Phillip Portoni. "Using Suction for Laminar Flow Control in Hypersonic Quiet Wind Tunnels: A Feasibility Study." Thesis, 2019.

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To reduce the risk of using suction in a hypersonic quiet-tunnel nozzle design, this project tested micro-perforated suction sections to remove the boundary layer on an axisymmetric model in the Boeing/AFOSR Mach-6 Quiet Tunnel. The model was a cone-flare geometry tested at 0° angle of attack. The turn from the 7° half-angle cone to the flare was designed to prevent flow separation. The flare was designed to amplify the Görtler instability.

Five suction sections were designed with different perforation patterns and porosities. Four were successfully manufactured, but only the first of the four sections has been tested so far. The first suction section has pores drilled along straight lines with a nominal 5% porosity.

Measurements were made with temperature-sensitive paint and oil-flow visualization on a non-perforated blank to measure the baseline development of Görtler vortices on the flare. Although the signal-to-noise ratio of the measurement techniques were insufficient to measure the vortices, it was confirmed that the boundary layer is laminar for the entire model. Measurements with suction also did not show the Görtler vortices.

Surface pressure fluctuations were measured on the flare. Apparent second-mode waves were detected. The suction measurements showed a slight increase in second-mode peak frequency over the baseline results, as expected.

Concerns had been raised about acoustic noise that might be radiated from the suction section. Thus, fluctuations above the suction section were measured using a pitot probe and using focused-laser differential interferometry. The measurements during suction showed no noticeable increase in fluctuations compared to the baseline results.
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(5930645), Kathryn A. Gray. "Flowfield Characterization of the Boeing/AFOSR Mach-6 Quiet Tunnel." Thesis, 2019.

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The quiet-flow capabilities of the Boeing/AFOSR Mach-6 Quiet Tunnel have been well established in the last decade, but a full characterization of the nozzle flow is an ongoing project. Pitot probes outtted with Kulite pressure transducers were used to further the investigation of the tunnel's flowfield. Noise levels were calculated by integrating the power spectral densities of the measured pitot pressure fluctuations, and experiments were performed to investigate several aspects of the flow.

First, the temperature distribution along the nozzle was varied to determine if heating had an effect on the stability of the laminar nozzle-wall boundary layer. Runs made with initial stagnation pressures slightly above the maximum quiet pressure determined that additional nozzle-wall heating did not have an effect on the amount of runtime which experienced quiet flow. In addition, pitot-probe measurements were taken at various locations to better determine the axial dependence of the noise levels. Experiments were also performed using pitot probes of varying forward-facing diameters to determine the effects of probe geometry on the measured fluctuations. The results were found to differ signicantly from simulations and from a previous set of experimental data, but a likely cause of the discrepancies was not found. A pitot probe mounted on the base of a cone confirmed that the aft end of a model does experience quiet flow. Finally, characterization of the flowfield was attempted when the tunnel is run using helium. The measured pressures for these experiments have a signicant level of uncertainty because the sensor calibration changes as helium diffuses across the diaphragm. Nevertheless, the measurements suggest that there may be periods of uniform flow, although these periods remain unstable and unsteady.


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Hofferth, Jerrod William. "Boundary-Layer Stability and Transition on a Flared Cone in a Mach 6 Quiet Wind Tunnel." Thesis, 2013. http://hdl.handle.net/1969.1/150990.

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A key remaining challenge in the design of hypersonic vehicles is the incomplete understanding of the process of boundary-layer transition. Turbulent heating rates are substantially higher than those for a laminar boundary layer, and large uncertainties in transition prediction therefore demand conservative, inefficient designs for thermal protection systems. It is only through close collaboration between theory, experiment, and computation that the state of the art can be advanced, but experiments relevant to flight require ground-test facilities with very low disturbance levels. To enable this work, a unique Mach 6 low-disturbance wind tunnel, previously of NASA Langley Research Center, is established within a new pressure-vacuum blow-down infrastructure at Texas A&M. A 40-second run time at constant conditions enables detailed measurements for comparison with computation. The freestream environment is extensively characterized, with a large region of low-disturbance flow found to be reliably present for unit Reynolds numbers Re < 11×10^6 m-1. Experiments are performed on a 5º half-angle flared cone model at Re = 10×10^6 m-1 and zero angle of attack. For the study of the second-mode instability, well-resolved boundary-layer profiles of mean and fluctuating mass flux are acquired at several axial locations using hot-wire probes with a bandwidth of 330 kHz. The second mode instability is observed to undergo significant growth between 250 and 310 kHz. Mode shapes of the disturbance agree well with those predicted from linear parabolized stability equation (LPSE) computations. A 17% (40 kHz) disagreement is observed in the frequency for most-amplified growth between experiment and LPSE. Possible sources of the disagreement are discussed, and the effect of small misalignments of the model is quantified experimentally. A focused schlieren deflectometer with high bandwidth (1 MHz) and high signal-to-noise ratio is employed to complement the hot-wire work. The second-mode fundamental at 250 kHz is observed, as well as additional harmonic content not discernible in the hot-wire measurements at two and three times the fundamental. A bispectral analysis shows that after sufficient amplification of the second mode, several nonlinear mechanisms become significant, including ones involving the third harmonic, which have not hitherto been reported in the literature.
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Books on the topic "Quiet Tunnels"

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Wolf, Stephen W. D. Supersonic wind tunnel nozzles: A selected, annotated bibliography to aid in the development of quiet wind tunnel technology. Washington, D.C: National Aeronautics and Space Administration, 1990.

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Schneider, Steven P. A quiet flow Ludwieg tube for study of transition in compressible boundary layers: Design and feasibility. West Lafayette, IN: School of Aeronautics and Astronautics, Purdue University, 1991.

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Schneider, Steven P. Development of quiet-flow supersonic wind tunnels for laminar-turbulent transition research: Final report. [Washington, DC: National Aeronautics and Space Administration, 1994.

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Schneider, Steven P. Supersonic quiet-tunnel development for laminar-turbulent transition research: Final report for NASA Langley grant NAG-1-1607. [Washington, DC: National Aeronautics and Space Administration, 1995.

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Barna, P. S. Results of tests performed on the acoustic quiet flow facility three-dimensional model tunnel: Progress report on the D.S.M.A. design. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1995.

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United States. National Aeronautics and Space Administration., ed. A quiet flow Ludwieg tube for study of transition in compressible boundary layers: Design and feasibility. [Washington, D.C: National Aeronautics and Space Administration, 1990.

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National Aeronautics and Space Administration (NASA) Staff. Development of Quiet-Flow Supersonic Wind Tunnels for Laminar-Turbulent Transition Research. Independently Published, 2018.

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Development of quiet-flow supersonic wind tunnels for laminar-turbulent transition research: Final report. [Washington, DC: National Aeronautics and Space Administration, 1994.

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United States. National Aeronautics and Space Administration., ed. Development of quiet-flow supersonic wind tunnels for laminar-turbulent transition research: Final report. [Washington, DC: National Aeronautics and Space Administration, 1994.

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United States. National Aeronautics and Space Administration., ed. Supersonic quiet-tunnel development for laminar-turbulent transition research: Final report for NASA Langley grant NAG-1-1607. [Washington, DC: National Aeronautics and Space Administration, 1995.

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Book chapters on the topic "Quiet Tunnels"

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Beckwith, Ivan E. "High-Speed Quiet Tunnels." In Advances in Soil Science, 49–51. New York, NY: Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3430-2_8.

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Pate, Samuel R. "Dominance of “Noise” on Boundary Layer Transition in Conventional Wind Tunnels — a Place for the “Quiet” Ballistic Range in Future Studies." In Advances in Soil Science, 77–87. New York, NY: Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3430-2_11.

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Shen, Junmou, Ying Zhang, Dan Wang, Ruiqu Li, and Jian Gong. "CFD Evaluation and Experiment Test of the Running Time of the Ludwieg Tube Quiet Wind Tunnel." In 31st International Symposium on Shock Waves 2, 221–30. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-91017-8_27.

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Xia, Dongrui, Lijiang Han, Yang Li, Lichuang Ma, and Junjie Yan. "Nonlinear Seismic Response Analysis of the Surrounding Rock-Tunnel System in the Mountain Areas Under SV Wave." In Advances in Transdisciplinary Engineering. IOS Press, 2021. http://dx.doi.org/10.3233/atde210185.

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The seismic responses and failure mechanisms of the tunnels embedded in the rock are quite different from those of the aboveground structures due to the dynamic interactions between tunnel and surrounding rock. In the previous studies, the tunnel models were under some extent of simplification without considering much of critical issues such as the three-dimensional (3D) characteristics, nonlinear mechanical properties or initial in-situ stress in the model, which are bound to bring the unpredictable errors in the evaluation of seismic response of tunnel-rock system. In this paper, some 3D nonlinear finite element models are established to evaluate the seismic response of surrounding rock-tunnel system in the mountain areas, considering the initial stress state of surrounding rock-tunnel system induced by gravity and excavation, General Mohr Coulomb nonlinear constitutive. Based on the proposed model, the optimal value of the longitudinal length of the model is firstly discussed to determine the value range of the model size. After that, a series of numerical parametric analyses are carried out to investigate the deformation of the surrounding rock. One important finding is that there exists a most unfavorable stress condition which makes the tunnel induce maximum seismic responses. Finally, the typical control variable method is employed to compare the results of the models established in this paper with those of the model considering or not some of significance factors, the comparison results further prove the necessity of establishing the 3D nonlinear model.
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Dylan, Huw, David V. Gioe, and Michael S. Goodman. "A ‘Gangster Act’: The Berlin Tunnel." In The CIA and the Pursuit of Security, 54–63. Edinburgh University Press, 2020. http://dx.doi.org/10.3366/edinburgh/9781474428842.003.0003.

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This chapter focuses on CIA activity in Berlin and the construction of the Berlin Tunnel with their British counterparts, also known as Operation Gold and Stopwatch. The aim was to intercept USSR communications, by digging a tunnel from the US sector of West Berlin. Bill Harvey was the central figure for the CIA. The chapter also details quite how close the US and UK were operational in this Operation, and the closeness in sharing of technology, and knowledge built upon mutual trust and recognition of expertise. The operation was betrayed. Operation Gold was compromised almost immediately by George Blake, a British intelligence officer, told the USSR. However the USSR did not use the opportunity to mislead the US and UK by sharing disinformation. Blake was too valuable. Document: The Berlin Tunnel Operation 1952-1956
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Luo, Yifan, Matteo Toso, Bailu Si, Federico Stella, and Alessandro Treves. "Grid Cells Lose Coherence in Realistic Environments." In Hippocampus - Cytoarchitecture and Diseases. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.100310.

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Spatial cognition in naturalistic environments, for freely moving animals, may pose quite different constraints from that studied in artificial laboratory settings. Hippocampal place cells indeed look quite different, but almost nothing is known about entorhinal cortex grid cells, in the wild. Simulating our self-organizing adaptation model of grid cell pattern formation, we consider a virtual rat randomly exploring a virtual burrow, with feedforward connectivity from place to grid units and recurrent connectivity between grid units. The virtual burrow was based on those observed by John B. Calhoun, including several chambers and tunnels. Our results indicate that lateral connectivity between grid units may enhance their “gridness” within a limited strength range, but the overall effect of the irregular geometry is to disable long-range and obstruct short-range order. What appears as a smooth continuous attractor in a flat box, kept rigid by recurrent connections, turns into an incoherent motley of unit clusters, flexible or outright unstable.
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Daub, Adrian. "The Ballad, the Public, and Gendered Community." In What the Ballad Knows, 211—C7.F1. Oxford University PressNew York, 2022. http://dx.doi.org/10.1093/oso/9780190885496.003.0008.

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Abstract By the mid-nineteenth century, the ballad was an emphatically bookish form—frequently anthologized, featured in periodicals, used in schoolbooks. But the ballad also still retained the power to create small communities—not quite a reading public, not just a family or classroom. And in particular it was used in, and used to create, gendered communities. In Berlin, a group of (male) artists, public servants, and academics met in a literary society called the “Tunnel over the Spree” (Berlin’s main river). They spent their meetings drinking and socializing, but their main focus was on literary competition—above all, their ballad contest ended up having an outsized influence on the direction the ballad would take in incipient German literary realism. This chapter contrasts the gender politics of balladry among the members of the “Tunnel” with those of women composers composing ballad settings—many of them had founded, or become associated with the choral societies that had sprung up across the German-speaking world in the first few decades of the century. Their efforts as composers reflected, but also sought critical distance from, the gender politics implied by the single-gender space of a choral academy or choral society.
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Rodden, John G. "After the Wall: Pride before the Fall, 1961–89." In Repainting the Little Red Schoolhouse. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195112443.003.0011.

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East Berlin. August 13, 1961. As the sun peeks over the horizon on this beautiful Sunday morning, most East Berliners sleep on, but some rise for work; a few thousand of them are Grenzgänger, who cross town—quite legally—to work in the “other” Berlin, mostly as hotel and restaurant employees and in other service jobs made lucrative by the uneven exchange rate. Each day they make the trip to West Berlin—by foot, by bicycle, by S-Bahn and U-Bahn, showing their DDR identity cards and special work permits to the bored Grepos (Grenzpolizei, border police) stationed at the gates. But this morning the Grepos are not bored; today, as the would-be commuters discover as they reach streets and subway stations along the East Berlin border, no Grenzgänger will cross. “Die Grenze ist geschlossen!” people scream to each other in the early-morning stillness. “The border is closed!” No subway cars are running westward; Grepos guard the U-Bahn tunnels to prevent subway commuters from fleeing to the West on foot; Vopos turn back Grenzgänger at every checkpoint. The SED has apparently found a way to secure its future and halt the flight of DDR and skilled labor—by walling them in. WHO HAS THE YOUTH, HAS THE FUTURE! As the Grenzgänger stumble home and the DDR capital—“die Hauptstadt der DDR”—awakens to the nightmare, it is as if a tremendous howl—the anguished wail of cornered, trapped, desperate animals—has gone up throughout East Berlin— as it soon will over the DDR. For almost a decade, East Germany’s 600-mile border has been sealed by barbed wire and 12-foot electrified fencing; just inside the fence is a strip of land about 50 yards wide that is cleared of brush, dotted with mines, and covered by machine guns in high watchtowers. And so, most aspiring refugees make their way to East Berlin, where many of the streets and subway stations along the city border are guarded casually, if at all.
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Beris, Antony N., and Brian J. Edwards. "Symplectic Geometry in Optics." In Thermodynamics of Flowing Systems: with Internal Microstructure. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195076943.003.0006.

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The scope of this book is to address the fundamental problem of modeling transport processes within complex systems, i.e., systems with internal microstructure. The classical engineering approach involves the modeling of the systems as structured continua and the subsequent use of the models in order to derive (if possible) analytical results, exact or approximate. The advent of powerful computers and the promise through parallel processing of even more substantial computational gains in the near future have introduced yet another paragon to the established engineering practice: that of the numerical simulation. Numerical simulation has emerged as a viable alternative to experiments (contrast Computational Fluid Dynamics (CFD) simulations versus wind tunnel experiments); however, the key limitation to a wider application of numerical simulations in engineering practice lies in the reliability of the models (as well as in their simplicity). CFD applications are successful since the Navier/Stokes equations which they employ are quite capable of describing accurately enough the hydrodynamics of air and water. However, as we move our emphasis to materials of such internal complexity as polymer melts, liquid crystals, suspensions, etc., the development of reliable continuum models becomes an increasingly arduous task. The main objective of this treatise is to investigate a more systematic approach through which continuum models may be developed and analyzed. The key issue that the modeler has to cope with is how to construct models which describe more of the underlying physics without, at the same time, becoming excessively complex so that they either require a prohibitively large, experimentally determined number of adjustable parameters (such as current phenomenological theories) or a prohibitively large computational time (such as required for a detailed “brute force” description of the molecular dynamics). It is the thesis of the present work that a lot of effort can be saved if the appropriate formulation is used in deriving model equations, a formulation which is capable of exploiting to a maximum degree the inherent symmetry and consistency of the collective phenomena exhibited by a large number of internal degrees of freedom.
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10

Schmickler, Wolfgang. "Theoretical considerations of electron-transfer reactions." In Interfacial Electrochemistry. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195089325.003.0011.

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Chemical and electrochemical reactions in condensed phases are generally quite complex processes; only outer-sphere electron-transfer reactions are sufficiently simple that we have reached a fair understanding of them in terms of microscopic concepts. In this chapter we give a simple derivation of a semiclassical theory of outer-sphere electron-transfer reactions, which was first systematically developed by Marcus and Hush in a series of papers. A more advanced treatment will be presented in Chapter 19. We begin with qualitative considerations. During the course of an outer-sphere electron-transfer reaction, the reactants get very close, up to a few Ångstroms, to the electrode surface. Electrons can tunnel over such a short distance, and the reaction would be very fast if nothing happened but the transfer of an electron. In fact, outer-sphere reactions are fast, but they have a measurable rate, and an energy of activation of typically 0.2 - 0.4 eV, since electron transfer is accompanied by reorganization processes of atoms and molecules that require thermal activation. While the reacting complex often has the same or similar structure in the oxidized and reduced form, metal-ligand bonds are typically shorter in the complex with the higher charge, which is also more strongly solvated. So the reaction is accompanied by a reorganization of both the complex, or inner sphere, and the solvation sheath, or outer sphere (see Fig. 6.1). These processes require an energy of activation and slow the reaction down. A natural question is: In which temporal order do the reorganization processes and the proper electron transfer take place? The answer is given by the Frank-Condon principle, which in this context, states: First the heavy particles of the inner and outer sphere must assume a suitable intermediate configuration, then the electron is exchanged isoenergetically, and finally the system relaxes to its new equilibrium configuration. A simple illustration is given in Fig. 6.2, where we have drawn potential energy surfaces for the reduced and the oxidized state as a function of two generalized reaction coordinates representing the positions of particles in the inner and outer sphere.
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Conference papers on the topic "Quiet Tunnels"

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Schneider, Steven. "The Development of Hypersonic Quiet Tunnels." In 37th AIAA Fluid Dynamics Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2007. http://dx.doi.org/10.2514/6.2007-4486.

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Lax, Philip, and Sergey B. Leonov. "Condensation-Limited Operational Maps of Notre Dame Large Quiet Tunnels." In AIAA SCITECH 2022 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2022. http://dx.doi.org/10.2514/6.2022-1719.

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Schneider, Steven P. "Developing Mechanism-Based Methods for Estimating Hypersonic Boundary-Layer Transition in Flight: The Role of Quiet Tunnels." In 43rd AIAA Fluid Dynamics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2013. http://dx.doi.org/10.2514/6.2013-2608.

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Redonnet, Stéphane, and Jean Bulte. "Numerical Investigation of the Refraction Effects by Jet Flows in Anechoic Wind Tunnels, with Application to NASA/LaRC Quiet Flow Facility." In 21st AIAA/CEAS Aeroacoustics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2015. http://dx.doi.org/10.2514/6.2015-3268.

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Hofferth, Jerrod, Rodney Bowersox, and William Saric. "The Mach 6 Quiet Tunnel at Texas A&M: Quiet Flow Performance." In 27th AIAA Aerodynamic Measurement Technology and Ground Testing Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2010. http://dx.doi.org/10.2514/6.2010-4794.

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Borg, Matthew, Steven Schneider, and Thomas Juliano. "Inlet Measurements and Quiet Flow Improvements in the Boeing/AFOSR Mach-6 Quiet Tunnel." In 44th AIAA Aerospace Sciences Meeting and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2006. http://dx.doi.org/10.2514/6.2006-1317.

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Erdos, John, and Robert Bakos. "Prospects for a quiet hypervelocity shock-expansion tunnel." In 25th Plasmadynamics and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1994. http://dx.doi.org/10.2514/6.1994-2500.

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Weiss, Julien, and Ndaona Chokani. "Quiet Tunnel Experiments of Shockwave / Turbulent Boundary Layer Interaction." In 36th AIAA Fluid Dynamics Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2006. http://dx.doi.org/10.2514/6.2006-3362.

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WILKINSON, S., S. ANDERS, F. J. CHEN, and I. BECKWITH. "Supersonic and hypersonic quiet tunnel technology at NASA Langley." In 28th Joint Propulsion Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1992. http://dx.doi.org/10.2514/6.1992-3908.

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Schneider, Steven, Shann Rufer, Craig Skoch, Erick Swanson, and Matthew Borg. "Instability and Transition in the Mach-6 Quiet Tunnel." In 34th AIAA Fluid Dynamics Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2004. http://dx.doi.org/10.2514/6.2004-2247.

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Reports on the topic "Quiet Tunnels"

1

Grossir, Guillaume. On the design of quiet hypersonic wind tunnels. Von Karman Institute for Fluid Dynamics, December 2020. http://dx.doi.org/10.35294/tm57.

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This document presents a thorough literature review on the development of hypersonic quiet tunnels. The concept of boundary layer transition in high-speed flows is presented first. Its consequences on the free-stream turbulence levels in ground facilities are reviewed next, demonstrating that running boundary layers along the nozzle walls must remain laminar for quiet operation. The design key points that enable laminar boundary layers and hypersonic operation with low free-stream noise levels are then identified and discussed. The few quiet facilities currently operating through the world are also presented, along with their design characteristics and performances. The expected characteristics and performances of a European quiet tunnel are also discussed, along with flow characterization methodologies and different measurement techniques. It is finally shown that the required expertise to establish the first European quiet hypersonic wind tunnel is mostly at hand.
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Knight, Doyle D., and Hadassah Naiman. Towards High-Reynolds Number Quiet Flow in Hypersonic Tunnels. Fort Belvoir, VA: Defense Technical Information Center, February 2009. http://dx.doi.org/10.21236/ada498212.

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Schneider, Steven P. Towards High-Reynolds-Number Quiet Flow in Hypersonic Wind Tunnels. Fort Belvoir, VA: Defense Technical Information Center, April 2009. http://dx.doi.org/10.21236/ada500049.

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Schneider, Steven P. Hypersonic Boundary-Layer Transition Research in the Boeing/AFOSR Mach-6 Quiet Tunnel. Fort Belvoir, VA: Defense Technical Information Center, March 2006. http://dx.doi.org/10.21236/ada448081.

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Segura, Rodrigo. Oscillations in a Forward-Facing Cavity Measured Using Laser-Differential Interferometry in a Hypersonic Quiet Tunnel. Fort Belvoir, VA: Defense Technical Information Center, December 2007. http://dx.doi.org/10.21236/ada474770.

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