WorldWideScience

Sample records for water tunnels

  1. Water Tunnel Facility

    Data.gov (United States)

    Federal Laboratory Consortium — NETL’s High-Pressure Water Tunnel Facility in Pittsburgh, PA, re-creates the conditions found 3,000 meters beneath the ocean’s surface, allowing scientists to study...

  2. Free Surface Water Tunnel (FSWT)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: The Free Surface Water Tunnel consists of the intake plenum, the test section and the exit plenum. The intake plenum starts with a perforated pipe that...

  3. Propulsion Systems in Water Tunnel

    Directory of Open Access Journals (Sweden)

    Nobuyuki Fujisawa

    1995-01-01

    agreement with the field experiment with prototype craft. Measurements are also made for the losses in the intake and the nozzle. The optimization study of the water jet systems is conducted by simulating the change of the nozzle outlet diameter with the variable nozzle arrangement. It is suggested that the nozzle outlet diameter should be decreased as the craft velocity increases to obtain an optimum propulsive efficiency in a wide range of craft velocity.

  4. Validation of a Compact Isokinetic Total Water Content Probe for Wind Tunnel Characterization at NASA Glenn Icing Research Tunnel and at NRC Ice Crystal Tunnel

    Science.gov (United States)

    Davison, Craig R.; Landreville, Charles; Ratvasky, Thomas P.

    2017-01-01

    A new compact isokinetic probe to measure total water content in a wind tunnel environment has been developed. The probe has been previously tested under altitude conditions. This paper presents a comprehensive validation of the probe under a range of liquid water conditions at sea level in the NASA Glenn Icing Research Tunnel and with ice crystals at sea level at the NRC wind tunnel. The compact isokinetic probe is compared to tunnel calibrations and other probes.

  5. Design of a High-Reynolds Number Recirculating Water Tunnel

    Science.gov (United States)

    Daniel, Libin; Elbing, Brian

    2014-11-01

    An experimental fluid mechanics laboratory focused on turbulent boundary layers, drag reduction techniques, multiphase flows and fluid-structure interactions has recently been established at Oklahoma State University. This laboratory has three primary components; (1) a recirculating water tunnel, (2) a multiphase pipe flow loop, and (3) a multi-scale flow visualization system. The design of the water tunnel is the focus of this talk. The criteria used for the water tunnel design was that it had to produce a momentum-thickness based Reynolds number in excess of 104, negligible flow acceleration due to boundary layer growth, maximize optical access for use of the flow visualization system, and minimize inlet flow non-uniformity. This Reynolds number was targeted to bridge the gap between typical university/commercial water tunnels (103) and the world's largest water tunnel facilities (105) . These objectives were achieved with a 152 mm (6-inch) square test section that is 1 m long and has a maximum flow speed of 10 m/s. The flow non-uniformity was mitigated with the use of a tandem honeycomb configuration, a settling chamber and an 8.5:1 contraction. The design process that produced this final design will be presented along with its current status.

  6. Tunnel backfill erosion by dilute water

    Energy Technology Data Exchange (ETDEWEB)

    Olin, M. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2014-03-15

    The goal was to estimate smectite release from tunnel backfill due to dilute groundwater pulse during post glacial conditions. The plan was to apply VTT's two different implementations (BESW{sub D} and BESW{sub S}) of well-known model of Neretnieks et al. (2009). It appeared difficult to produce repeatable results using this model in COMSOL 4.2 environment, therefore a semi-analytical approximate approach was applied, which enabled to take into account both different geometry and smectite content in tunnel backfill as compared to buffer case. The results are quite similar to buffer results due to the decreasing effect of smaller smectite content and the increasing effect of larger radius. (orig.)

  7. Vibration-rotation-tunneling dynamics in small water clusters

    Energy Technology Data Exchange (ETDEWEB)

    Pugliano, N.

    1992-11-01

    The goal of this work is to characterize the intermolecular vibrations of small water clusters. Using tunable far infrared laser absorption spectroscopy, large amplitude vibration-rotation-tunneling (VRT) dynamics in vibrationally excited states of the water dimer and the water trimer are investigated. This study begins with the measurement of 12 VRT subbands, consisting of approximately 230 transitions, which are assigned to an 82.6 cm{sup {minus}1} intermolecular vibration of the water dimer-d{sub 4}. Each of the VRT subbands originate from K{sub a}{double_prime}=0 and terminate in either K{sub a}{prime}=0 or 1. These data provide a complete characterization of the tunneling dynamics in the vibrationally excited state as well as definitive symmetry labels for all VRT energy levels. Furthermore, an accurate value for the A{prime} rotational constant is found to agree well with its corresponding ground state value. All other excited state rotational constants are fitted, and discussed in terms of the corresponding ground state constants. In this vibration, the quantum tunneling motions are determined to exhibit large dependencies with both the K{sub a}{prime} quantum number and the vibrational coordinate, as is evidenced by the measured tunneling splittings. The generalized internal-axis-method treatment which has been developed to model the tunneling dynamics, is considered for the qualitative description of each tunneling pathway, however, the variation of tunneling splittings with vibrational excitation indicate that the high barrier approximation does not appear to be applicable for this vibrational coordinate. The data are consistent with a motion possessing a{prime} symmetry, and the vibration is assigned as the {nu}{sub 12} acceptor bending coordinate. This assignment is in agreement with the vibrational symmetry, the resultsof high level ab initio calculations, and preliminary data assigned to the analogous vibration in the D{sub 2}O-DOH isotopomer.

  8. Vibration-rotation-tunneling dynamics in small water clusters

    Energy Technology Data Exchange (ETDEWEB)

    Pugliano, N.

    1992-11-01

    The goal of this work is to characterize the intermolecular vibrations of small water clusters. Using tunable far infrared laser absorption spectroscopy, large amplitude vibration-rotation-tunneling (VRT) dynamics in vibrationally excited states of the water dimer and the water trimer are investigated. This study begins with the measurement of 12 VRT subbands, consisting of approximately 230 transitions, which are assigned to an 82.6 cm[sup [minus]1] intermolecular vibration of the water dimer-d[sub 4]. Each of the VRT subbands originate from K[sub a][double prime]=0 and terminate in either K[sub a][prime]=0 or 1. These data provide a complete characterization of the tunneling dynamics in the vibrationally excited state as well as definitive symmetry labels for all VRT energy levels. Furthermore, an accurate value for the A[prime] rotational constant is found to agree well with its corresponding ground state value. All other excited state rotational constants are fitted, and discussed in terms of the corresponding ground state constants. In this vibration, the quantum tunneling motions are determined to exhibit large dependencies with both the K[sub a][prime] quantum number and the vibrational coordinate, as is evidenced by the measured tunneling splittings. The generalized internal-axis-method treatment which has been developed to model the tunneling dynamics, is considered for the qualitative description of each tunneling pathway, however, the variation of tunneling splittings with vibrational excitation indicate that the high barrier approximation does not appear to be applicable for this vibrational coordinate. The data are consistent with a motion possessing a[prime] symmetry, and the vibration is assigned as the [nu][sub 12] acceptor bending coordinate. This assignment is in agreement with the vibrational symmetry, the resultsof high level ab initio calculations, and preliminary data assigned to the analogous vibration in the D[sub 2]O-DOH isotopomer.

  9. Application of Particle Image Velocimetry Technology in Water Tunnel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A display and analysis system for hermetical flow field in water tunnel is developed based on the particle image velocimetry(PIV) technology. It consists of some subsystems, such as lamp-house, imaging, image processing and analyzing, control and particles putting. Taking the flow fields around a sphere and a cylinder model as an example under higher Renolds number 5.8 × 105 in water tunnel, we inquired into the application of the system to water tunnel experiment by cross correlation algorithm. The measure error is less than 2 %. The test results show that the developed system can measure and display the flow field accurately in complex flow field without touching and disturbing. The research work indicates that PIV has lots of potential applications in the underwater flow field measurement.

  10. Turbine endwall two-cylinder program. [wind tunnel and water tunnel investigation of three dimensional separation of fluid flow

    Science.gov (United States)

    Langston, L. S.

    1980-01-01

    Progress is reported in an effort to study the three dimensional separation of fluid flow around two isolated cylinders mounted on an endwall. The design and performance of a hydrogen bubble generator for water tunnel tests to determine bulk flow properties and to measure main stream velocity and boundary layer thickness are described. Although the water tunnel tests are behind schedule because of inlet distortion problems, tests are far enough along to indicate cylinder spacing, wall effects and low Reynolds number behavior, all of which impacted wind tunnel model design. The construction, assembly, and operation of the wind tunnel and the check out of its characteristics are described. An off-body potential flow program was adapted to calculate normal streams streamwise pressure gradients at the saddle point locations.

  11. Quantum Tunneling of Water in Beryl: A New State of the Water Molecule.

    Science.gov (United States)

    Kolesnikov, Alexander I; Reiter, George F; Choudhury, Narayani; Prisk, Timothy R; Mamontov, Eugene; Podlesnyak, Andrey; Ehlers, George; Seel, Andrew G; Wesolowski, David J; Anovitz, Lawrence M

    2016-04-22

    Using neutron scattering and ab initio simulations, we document the discovery of a new "quantum tunneling state" of the water molecule confined in 5 Å channels in the mineral beryl, characterized by extended proton and electron delocalization. We observed a number of peaks in the inelastic neutron scattering spectra that were uniquely assigned to water quantum tunneling. In addition, the water proton momentum distribution was measured with deep inelastic neutron scattering, which directly revealed coherent delocalization of the protons in the ground state.

  12. Design and Development of Low-Cost Water Tunnel for Educational Purpose

    Science.gov (United States)

    Zahari, M.; Dol, S. S.

    2015-04-01

    The hydrodynamic behaviour of immersed body is essential in fluid dynamics study. Water tunnel is an example of facility required to provide a controlled condition for fluid flow research. The operational principle of water tunnel is quite similar to the wind tunnel but with different working fluid and higher flow-pumping capacity. Flow visualization in wind tunnel is more difficult to conduct as turbulent flows in wind dissipate quickly whilst water tunnel is more suitable for such purpose due to higher fluid viscosity and wide variety of visualization techniques can be employed. The present work focusses on the design and development of open flow water tunnel for the purpose of studying vortex-induced vibration from turbulent vortex shedding phenomenon. The water tunnel is designed to provide a steady and uniform flow speed within the test section area. Construction details are discussed for development of low-cost water tunnel for quantitative and qualitative fluid flow measurements. The water tunnel can also be used for educational purpose such as fluid dynamics class activity to provide quick access to visualization medium for better understanding of various turbulence motion learnt in class.

  13. Signatures of Quantum-Tunneling Diffusion of Hydrogen Atoms on Water Ice at 10 K

    OpenAIRE

    2015-01-01

    Reported here is the first observation of the tunneling surface diffusion of a hydrogen (H) atom on water ice. Photostimulated desorption and resonance-enhanced multiphoton ionization methods were used to determine the diffusion rates at 10 Kon amorphous solid water and polycrystalline ice. H-atom diffusion on polycrystalline ice was 2 orders of magnitude faster than that of deuterium atoms, indicating the occurrence of tunneling diffusion. Whether diffusion is by tunneling or thermal hopping...

  14. Water table tests of proposed heat transfer tunnels for small turbine vanes

    Science.gov (United States)

    Meitner, P. L.

    1974-01-01

    Water-table flow tests were conducted for proposed heat-transfer tunnels which were designed to provide uniform flow into their respective test sections of a single core engine turbine vane and a full annular ring of helicopter turbine vanes. Water-table tests were also performed for the single-vane test section of the core engine tunnel. The flow in the heat-transfer tunnels was shown to be acceptable.

  15. Communication: Isotopic effects on tunneling motions in the water trimer

    Energy Technology Data Exchange (ETDEWEB)

    Videla, Pablo E. [Departamento de Química Inorgánica Analítica y Química-Física e INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, 1428 Buenos Aires (Argentina); Rossky, Peter J. [Department of Chemistry, Rice University, Houston, Texas 77251-1892 (United States); Laria, D., E-mail: dhlaria@cnea.gov.ar [Departamento de Química Inorgánica Analítica y Química-Física e INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, 1428 Buenos Aires (Argentina); Departamento de Física de la Materia Condensada, Comisión Nacional de Energía Atómica, Avenida Libertador 8250, 1429 Buenos Aires (Argentina)

    2016-02-14

    We present results of ring polymer molecular dynamics simulations that shed light on the effects of nuclear quantum fluctuations on tunneling motions in cyclic [H{sub 2}O]{sub 3} and [D{sub 2}O]{sub 3}, at the representative temperature of T = 75 K. In particular, we focus attention on free energies associated with two key isomerization processes: The first one corresponds to flipping transitions of dangling OH bonds, between up and down positions with respect to the O–O–O plane of the cluster; the second involves the interchange between connecting and dangling hydrogen bond character of the H-atoms in a tagged water molecule. Zero point energy and tunneling effects lead to sensible reductions of the free energy barriers. Due to the lighter nature of the H nuclei, these modifications are more marked in [H{sub 2}O]{sub 3} than in [D{sub 2}O]{sub 3}. Estimates of the characteristic time scales describing the flipping transitions are consistent with those predicted based on standard transition-state-approximation arguments.

  16. Prevention and treatment technologies of railway tunnel water inrush and mud gushing in China

    Institute of Scientific and Technical Information of China (English)

    Yong Zhao; Pengfei Li; Siming Tian

    2013-01-01

    Water inrush and mud gushing are one of the biggest hazards in tunnel construction. Unfavorable geo-logical sections can be observed in almost all railway tunnels under construction or to be constructed, and vary in extent. Furthermore, due to the different heights of mountains and the lengths of tunnels, the locations of the unfavorable geological sections cannot be fully determined before construction, which increases the risk of water inrush and mud gushing. Based on numerous cases of water inrush and mud gushing in railway tunnels, the paper tries to classify water inrush and mud gushing in railway tunnels in view of the conditions of the surrounding rocks and meteorological factors associated with tunnel excavation. In addition, the causes of water inrush and mud gushing in combination of macro-and micro-mechanisms are summarized, and site-specific treatment method is put forward. The treatment methods include choosing a method of advance geological forecast according to risk degrees of different sec-tions in the tunnel, determining the items of predictions, and choosing the appropriate methods, i.e. draining-oriented method, blocking-oriented method or draining-and-blocking method. The treatment technologies of railway water inrush and mud gushing are also summarized, including energy relief and pressure relief technology, advance grouting technology, and advance jet grouting technology associated with their key technical features and applicable conditions. The results in terms of treatment methods can provide reference to the prevention and treatment of tunnel water inrush and mud gushing.

  17. Enhancement of Cross-Borehole Pulse Radar Signature on a Partially Water-Filled Tunnel

    Directory of Open Access Journals (Sweden)

    Ji-Hyun Jung

    2014-01-01

    Full Text Available Cross-borehole pulse radar has been employed to detect a deeply located empty tunnel. In this paper, effects of underground water collected in the bottom of an empty tunnel on cross-borehole pulse radar signatures are analyzed numerically. B-scan images, stacks of received pulses, are calculated by applying the finite-difference time-domain (FDTD method for 6 different heights of water from the bottom to the half height inside an empty tunnel. The most important features of an empty tunnel, the fastest time of peak (TOP and time of arrival (TOA extracted from the B-scan images, are slowed considerably depending on the increased height of water inside the tunnel. To compensate the weak TOP like that of an empty tunnel, a relation curve is formulated only utilizing measurable parameters of the fastest TOP and the fastest TOA. Then, a unified curve including the effects of two granites with the low and high dielectric properties is derived to cover widely varied dielectric properties of underground rocks. Based on the fastest TOP of an empty tunnel, the average difference between the fastest TOP of an empty tunnel and that of a partially water-filled tunnel decreases from 22.92% to 2.59% after enhancement.

  18. Modeling of Turbidity Variation in Two Reservoirs Connected by a Water Transfer Tunnel in South Korea

    Directory of Open Access Journals (Sweden)

    Jae Chung Park

    2017-06-01

    Full Text Available The Andong and Imha reservoirs in South Korea are connected by a water transfer tunnel. The turbidity of the Imha reservoir is much higher than that of the Andong reservoir. Thus, it is necessary to examine the movement of turbidity between the two reservoirs via the water transfer tunnel. The aim of this study was to investigate the effect of the water transfer tunnel on the turbidity behavior of the two connecting reservoirs and to further understand the effect of reservoir turbidity distribution as a function of the selective withdrawal depth. This study applied the CE-QUAL-W2, a water quality and 2-dimensional hydrodynamic model, for simulating the hydrodynamic processes of the two reservoirs. Results indicate that, in the Andong reservoir, the turbidity of the released water with the water transfer tunnel was similar to that without the tunnel. However, in the Imha reservoir, the turbidity of the released water with the water transfer tunnel was lower than that without the tunnel. This can be attributed to the higher capacity of the Andong reservoir, which has double the storage of the Imha reservoir. Withdrawal turbidity in the Imha reservoir was investigated using the water transfer tunnel. This study applied three withdrawal selections as elevation (EL. 141.0 m, 146.5 m, and 152.0 m. The highest withdrawal turbidity resulted in EL. 141.0 m, which indicates that the high turbidity current is located at a vertical depth of about 20–30 m because of the density difference. These results will be helpful for understanding the release and selective withdrawal turbidity behaviors for a water transfer tunnel between two reservoirs.

  19. An Assessment of the Usefulness of Water Tunnels for Aerodynamic Investigations

    Science.gov (United States)

    2012-12-01

    in a water tunnel experiment on a 12-inch-span 3D - printed model of the 1303 UCAV configuration in a water tunnel -see Ol (2006). The wind-and water...Figure 22. The 1303 UCAV configuration: five-foot-span model installed in QinetiQ 5 m wind tunnel –see Bruce & Mundel (2003), and 3D - printed ... turbine blades , and the emerging area of Micro Air Vehicles (MAVs). For the latter, sharp- edged swept wings are perhaps the most celebrated example

  20. Reviving Ancient Water Tunnels in the Desert - Digging for Gold?

    Institute of Scientific and Technical Information of China (English)

    Joshka Wessels

    2005-01-01

    The water shortage in the Middle East is a well-known problem. The introduction of diesel operated pumps for irrigation has caused a severe drop in groundwater levels. At the same time the demand for groundwater is growing to alarming proportions. Alternative ways of groundwater supply and management need to be found to halt social and economical disaster in the future. Why not look at history? Qanats are subterranean tunnels ancient civilizations built to access groundwater. The technique is a sustainable method of groundwater extraction. Throughout the Middle East some settlements still make use of these ancient systems. In the summer of 2000, a community rehabilitation of a qanat was executed with support from the International Center for Agricultural Research in Dry Areas (ICARDA) and international donors. The renovation served as a pilot community intervention within a participatory action research project aimed at evaluating the use of qanats in Syria. In a second stage of the project, the pilot was scaled up to a nation-wide survey of Syrian qanats in 2OO1. This resulted in qanat renovations on other sites executed in 2002 and 2003 with further international support.This paper compares the first pilot renovation with a recent qanat renovation that took place in Qarah,Syria.

  1. Design and installation of a high Reynolds number recirculating water tunnel

    Science.gov (United States)

    Daniel, Libin

    The High-Reynolds Number Fluid Mechanics Laboratory has recently been established at Oklahoma State University (OSU). The three primary components of the laboratory are 1) a recirculating water tunnel, 2) a multiphase pipe flow facility, and 3) a multi-scale flow visualization system. This thesis focuses on the design and fabrication of the water tunnel, which will be used for high-Reynolds number turbulent boundary layer research. Two main design criteria for the water tunnel were to achieve a momentum thickness based Reynolds number in excess of 104 and to have high optical access to the flow surfaces in the test section. This is being achieved with a 1 m. long test section and a maximum flow speed of 10 m/s. This Reynolds number was targeted to bridge the gap between typical university water tunnels (103) and the world's largest water tunnel facilities (105). The water tunnel is powered by a 150 hp motor and a 4500 gpm capacity centrifugal pump. The water tunnel is designed for a maximum operating pressure of 40 psi. This will make the facility a low cost option to perform high-Reynolds number aerodynamic and hydrodynamic tests. Improved flow imaging capability is a major advantage to liquid based fluid facilities because of the increased density for seeding and reduced field-of-view for equivalent Reynolds number. The laboratory's state-of-the-art flow visualization system can be used for time-resolved and phase averaged stereo- particle-image-velocimetry (sPIV), laser-induced-fluorescence, and high-speed imaging. Design provisions are also made to allow a multi-phase loop to share the pump and motor configuration of this water tunnel facility. The major design decisions that went into the design of the water tunnel facility are discussed. The design considerations that were taken into account for the test section, flow conditioning sections and the entire flow loop are discussed in greater detail. The final configuration and the technical drawings of the water

  2. 3D Finite Element Simulation of Tunnel Boring Machine Construction Processes in Deep Water Conveyance Tunnel

    Institute of Scientific and Technical Information of China (English)

    ZHONG Denghua; TONG Dawei

    2009-01-01

    Applying stiffness migration method, a 3D finite element mechanical model is established to simulate the excavation and advance processes. By using 3D nonlinear finite element method, the tunnel boring machine (TBM) excavation process is dynamically simulated to analyze the stress and strain field status of surrounding rock and segment. The maximum tensile stress of segment ring caused by tunnel construction mainly lies in arch bottom and presents zonal distribution. The stress increases slightly and limitedly in the course of excavation. The maxi-mum and minimum displacements of segment, manifesting as zonal distribution, distribute in arch bottom and vault respectively. The displacements slightly increase with the advance of TBM and gradually tend to stability.

  3. Investigating hydraulic connections and the origin of water in a mine tunnel using stable isotopes and hydrographs

    Science.gov (United States)

    Walton-Day, Katherine; Poeter, Eileen

    2009-01-01

    Turquoise Lake is a water-supply reservoir located north of the historic Sugarloaf Mining district near Leadville, Colorado, USA. Elevated water levels in the reservoir may increase flow of low-quality water from abandoned mine tunnels in the Sugarloaf District and degrade water quality downstream. The objective of this study was to understand the sources of water to Dinero mine drainage tunnel and evaluate whether or not there was a direct hydrologic connection between Dinero mine tunnel and Turquoise Lake from late 2002 to early 2008. This study utilized hydrograph data from nearby draining mine tunnels and the lake, and stable isotope (δ18O and δ2H) data from the lake, nearby draining mine tunnels, imported water, and springs to characterize water sources in the study area. Hydrograph results indicate that flow from the Dinero mine tunnel decreased 26% (2006) and 10% (2007) when lake elevation (above mean sea level) decreased below approximately 3004 m (approximately 9855 feet). Results of isotope analysis delineated two meteoric water lines in the study area. One line characterizes surface water and water imported to the study area from the western side of the Continental Divide. The other line characterizes groundwater including draining mine tunnels, springs, and seeps. Isotope mixing calculations indicate that water from Turquoise Lake or seasonal groundwater recharge from snowmelt represents approximately 10% or less of the water in Dinero mine tunnel. However, most of the water in Dinero mine tunnel is from deep groundwater having minimal isotopic variation. The asymmetric shape of the Dinero mine tunnel hydrograph may indicate that a limited mine pool exists behind a collapse in the tunnel and attenutates seasonal recharge. Alternatively, a conceptual model is presented (and supported with MODFLOW simulations) that is consistent with current and previous data collected in the study area, and illustrates how fluctuating lake levels change the local water

  4. Initial excess pore water pressures induced by tunnelling in soft ground

    Institute of Scientific and Technical Information of China (English)

    梁荣柱; 夏唐代; 林存刚; 俞峰; 吴世明

    2015-01-01

    Tunnelling-induced long-term consolidation settlement attracts a great interest of engineering practice. The distribution and magnitude of tunnelling-induced initial excess pore water pressure have significant effects on the long-term consolidation settlement. A simple and reliable method for predicting the tunnel-induced initial excess pore water pressure calculation in soft clay is proposed. This method is based on the theory of elasticity and SKEMPTON’s excess pore water pressure theory. Compared with the previously published field measurements and the finite-element modelling results, it is found that the suggested initial excess pore water pressure theory is in a good agreement with the measurements and the FE results. A series of parametric analyses are also carried out to investigate the influences of different factors on the distribution and magnitude of the initial excess pore water pressure in soft ground.

  5. Treatment of tunnel wash waters - experiments with organic sorbent materials. Part Ⅱ: Removal of toxic metals

    Institute of Scientific and Technical Information of China (English)

    PARUCH Adam M; ROSETH Roger

    2008-01-01

    In the first part of the article, the column and the bag experiments concerning removal of polycyclic aromatic hydrocarbons (PAHs) and nonpolar oil (NPO) from tunnel wash waters using organic sorbent materials have been described. This part presents the results of removal of toxic metals. The metals of concern (Al, As, Cd, Cr, Cu, Fe, Pb, Mo, Ni, and Zn) were selected based on the priority toxicant pollutants defined in surface water quality criteria. Concentrations of these metals in the collected effluents varied more than the concentrations of PAHs and NPO, and thus only metal contents were considered for statistical analyses. These analyses determined significant differences (P<0.05, P<0.01, and P<0.001) between the mean metal concentrations in the column effluents and those in applied wash water of road tunnel. The results obtained during both experiments revealed that the organic sorbents, and in particular their combination, removed toxic metals more effectively from wash water of road tunnel than from wash water of tunnel electrostatic filters. Among the investigated toxicants, Al and Fe showed the highest levels of reduction in the column experiment, 99.7% and 99.6%, respectively. The lowest reduction levels of 66.0% and 76.2% were found for Pb and Mo, respectively. The results of the bag experiment showed that even one day treatment of wash waters from tunnel electrostatic filters could reduce concentration of some toxicants by more than 70% (Al and Fe) and 80% (Cu).

  6. Numerical Analysis of Effect of Water on Explosive Wave Propagation in Tunnels and Surrounding Rock

    Institute of Scientific and Technical Information of China (English)

    XIA Chang-jing; SONG Zhen-duo; TIAN Lu-lu; LIU Hong-bin; WANG Lu; WU Xiao-fang

    2007-01-01

    Based on the application of practical engineering, propagation processes of explosive waves in rock with water well and tunnel are simulated by ANSYS/LS-DYNA software. The evolution of damage in rock is presented. The effect of water on the damage of the concrete slab in a tunnel is compared with damage inflicted without water. The numerical simulation illustrates that water plays an important role in the evolution of damage of the concrete slab in a mine tunnel. In the presence of water in the rock the concrete slab is damaged more severely than without water in rock. The effect of water location in the rock is also considered. It is found that the concrete slab in the tunnel shows various degrees of damage as a function of the different locations of water. Attenuation laws of stress waves over time-space in rock with water are also obtained. Numerical results indicate that, under blast loading, there are three zones in the rock: a crushed zone nearby the explosive charge, a damaged zone and an elastic zone. The conclusions of numerical analysis may provide references for blasting designs and structure protection.

  7. Water flow in fractured rock masses: numerical modeling for tunnel inflow assessment

    Science.gov (United States)

    Gattinoni, P.; Scesi, L.; Terrana, S.

    2009-04-01

    Water circulation in rocks represents a very important element to solve many problems linked with civil, environmental and mining engineering. In particular, the interaction of tunnelling with groundwater has become a very relevant problem not only due to the need to safeguard water resources from impoverishment and from the pollution risk, but also to guarantee the safety of workers and to assure the efficiency of the tunnel drainage systems. The evaluation of the hydrogeological risk linked to the underground excavation is very complex, either for the large number of variables involved or for the lack of data available during the planning stage. The study is aimed to quantify the influence of some geo-structural parameters (i.e. discontinuities dip and dip direction) on the tunnel drainage process, comparing the traditional analytical method to the modeling approach, with specific reference to the case of anisotropic rock masses. To forecast the tunnel inflows, a few Authors suggest analytic formulations (Goodman et al., 1965; Knutsson et al., 1996; Ribacchi et al., 2002; Park et al., 2008; Perrochet et al., 2007; Cesano et al., 2003; Hwang et al., 2007), valid for infinite, homogeneous and isotropic aquifer, in which the permeability value is given as a modulus of equivalent hydraulic conductivity Keq. On the contrary, in discontinuous rock masses the water flow is strongly controlled by joints orientation, by their hydraulic characteristics and by rocks fracturing conditions. The analytic equations found in the technical literature could be very useful, but often they don't reflect the real phenomena of the tunnel inflow in rock masses. Actually, these equations are based on the hypothesis of homogeneous aquifer, and then they don't give good agreement for an heterogeneous fractured medium. In this latter case, the numerical modelling could provide the best results, but only with a detailed conceptual model of the water circulation, high costs and long

  8. Stresses and Shear Fracture Zone of Jinshazhou Tunnel Surrounding Rock in Rich Water Region

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jun-jie; LOU Xiao-ming

    2008-01-01

    Field evidence has shown that large-scale and unstable discontinuous planes in the rock mass surrounding tunnels in rich water region are probably generated after excavation. The tunnel surrounding rock was divided into three zones, including elastic zone, plastic damage zone and shear fracture zone fof assessing the stability of the tunnel surrounding rock. By local hydrogeology, the stresses of surrounding rock of Jinshazhou circular tunnel was analyzed and the stress solutions on the elastic and plastic damage zones were obtained by applying the theories of fluid-solid coupling and elasto-plastic damage mechanics. The shear fracture zone generated by joints was studied and its range was determined by using Mohr-Coulomb strength criterion. Finally, the correctness of the theoretical results was validated by comparing the scopes of shear fracture zones calculated in this paper with those from literature.

  9. The Shanggongshan Tunnel Kunming Zhangjiuhe River Water Diversion and Water Supply Project

    Institute of Scientific and Technical Information of China (English)

    J. P. Kaegi; M. Bachmann; A. Colombi

    2004-01-01

    Kunming is the political and economical centre of the Yunnan Province in the south -west of China and one of the most beautiful historical and cultural cities in China. It is also one of the 14 cities in China that are severely short of water. In order to solve the supply problem and to allow for future development of the local society and economy, the "Kunming Zhangjiuhe River Water Diversion and Water Supply Project" was implemented. The total investment for the project is about USD 476 million.The objective is to establish a water supply system with a capacity of 0.6 million tons of water per day.Major parts of the project are:capacity by 0. 442 billion m3 and an annual water supply of 0. 245 billion m3;tunnels, but also some siphons);pacity of 0.4 million tons per day in the initial stage and 0.6 million tons per day once completed;length of 93.43 km;sons.Project completion is planned for the end of 2006.

  10. A laser fluorescence anemometer system for the Langley 16- by 24-inch water tunnel

    Science.gov (United States)

    Owen, F. K.; Orngard, Gary M.; Neuhart, Dan H.

    1991-01-01

    A laser fluorescence anemometer which comprises a three-component laser Doppler velocimeter system with a fourth channel to measure fluorescent dye concentration has been installed in the NASA Langley 16- by 24-in water tunnel. The system includes custom designed optics, data acquisition, and traverse control instruments and a custom software package. Feasibility studies demonstrated how water tunnels can be used in conjunction with advanced optical techniques to provide nonintrusive detailed flow field measurements of complex fluid flows with a minimum of expense. The measurements show that the laser fluorescence anemometer can provide new insight into the structure, entrainment, control and of mixing vortical and shear layer flows.

  11. 3D Finite Element Analysis of TBM Water Diversion Tunnel Segment Coupled with Seepage Field

    Institute of Scientific and Technical Information of China (English)

    钟登华; 胡能明; 程正飞; 吕鹏; 佟大威

    2016-01-01

    In most studies of tunnel boring machine(TBM)tunnelling, the groundwater pressure was not consid-ered, or was simplified and exerted on the boundary of lining structure. Meanwhile, the leakage, which mainly oc-curs in the segment joints, was often ignored in the relevant studies of TBM tunnelling. Additionally, the geological models in these studies were simplified to different extents, and mostly were simplified as homogenous bodies. Considering the deficiencies above, a 3D refined model of the surrounding rock of a tunnel is firstly established using NURBS-TIN-BReP hybrid data structure in this paper. Then the seepage field of the surrounding rock con-sidering the leakage in the segment joints is simulated. Finally, the stability of TBM water diversion tunnel is stud-ied coupled with the seepage simulation, to analyze the stress-strain conditions, the axial force and the bending moment of tunnel segment considering the leakage in the segment joints. The results illustrate that the maximum radial displacement, the minimum principal stress, the maximum principal stress and the axial force of segment lining considering the seepage effect are all larger than those disregarding the seepage effect.

  12. Influence of underground water seepage flow on surrounding rock deformation of multi-arch tunnel

    Institute of Scientific and Technical Information of China (English)

    LI Xi-bing; ZHANG Wei; LI Di-yuan; WANG Qi-sheng

    2008-01-01

    Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underground water seepage flow was taken into account or not. The distribution of displacement field around the multi-arch tunnel, which is influenced by the seepage field, was gained. The result indicates that the settlement values of the vault derived from coupling analysis are bigger when considering the seepage flow effect than that not considering. Through the contrast of arch subsidence quantities calculated by two kinds of computation situations, and the comparison between the calculated and measured value of tunnel vault settlement, it is found that the calculated value(5.7-6.0 mm) derived from considering the seepage effect is more close to the measured value(5.8-6.8 mm).Therefore, it is quite necessary to consider the seepage flow effect of the underground water in aquiferous stratum for multi-arch tunnel design.

  13. Vortex breakdown and control experiments in the Ames-Dryden water tunnel

    Science.gov (United States)

    Owen, F. K.; Peake, D. J.

    1987-01-01

    Flow-field measurements have been made to determine the effects of core blowing on vortex breakdown and control. The results of these proof-of-concept experiments clearly demonstrate the usefulness of water tunnels as test platforms for advanced flow-field simulation and measurement.

  14. HYDRAULIC CHARACTERISTICS OF WATER-WINGS FOR THE MIDDLE-PIER OF A DISCHARGE TUNNEL

    Institute of Scientific and Technical Information of China (English)

    WU Jian-hua; CAI Chang-guang; JI Wei; RUAN Shi-ping

    2006-01-01

    Water-wings, induced by the middle-pier placed in the inlet of a discharge tunnel, have harmful effects on the operation of the discharge tunnel.Based on dimensional analysis and physical model tests, the hydraulic characteristics of water-wings were investigated and their causes were analyzed in this study.The results show that the height and length of the water-wings increased with the increase of three factors, i.e., the Froude number Frd of the outlet of the pressure section, the depth Hc of the water surface concave at the end of the middle-pier, and the impact length Li of the two flows after this end.

  15. Quantifying Density, Water Adsorption and Equilibration Properties of Wind Tunnel Materials

    Science.gov (United States)

    Yu, Xinting; Horst, Sarah; He, Chao; Bridges, Nathan; Burr, Devon M.; Sebree, Joshua

    2016-10-01

    Aeolian processes are found on various planetary bodies including Earth, Venus, Mars, Titan, Triton, Pluto, and Comet 67P. Wind tunnels can simulate aeolian processes under different planetary parameters, with the robustness of results relying on experimental conditions and understanding of experimental materials. Threshold wind speed, the minimum wind speed to initiate saltation, is one parameter that can be investigated in wind tunnels. Liquid water adsorbed on wind tunnel materials could greatly enhance the threshold wind speed by increasing the interparticle force, density, and effective size of particles. Previous studies have shown that this effect could increase the threshold by 100% by putting 0.3-0.6% of water into typical dry quartz sand (Fecan et al. 1998). In order to simulate the weight of particles on other planetary bodies where gravity is significantly lower than on Earth, low-density materials are used in planetary wind tunnels, including walnut shells, activated charcoal, iced tea, and instant coffee.We first quantified the densities for all wind tunnel materials using a pycnometer and updated the density for low-density materials (e.g., walnut shells have density of 1.4 g/cm3 instead of 1.1 g/cm3 in the literature (Greeley et al. 1980)). Then we present a set of measurements that quantify water adsorption for both low and high-density materials (sand, basalt, and chromite). We first measured the water content and equilibration timescales for the materials through gravimetric measurements. We found low-density materials tend to have much more water (>5%) compared to high-density materials ( 6 hrs) compared to high-density materials (10-50 minutes). Since only water adsorbed on the particle surface would change the interparticle force, we then separate the surface and internal water using thermo-gravimetric analysis, and found that >80% of the water is still on the surface. Thus we assume water adsorption for low-density materials could greatly

  16. EXPERIMENTAL STUDY ON CAVITATION AND WATER-WING FOR MIDDLE-PIERS OF DISCHARGE TUNNELS

    Institute of Scientific and Technical Information of China (English)

    WU Jian-hua; CAI Chang-guang; JI Wei; RUAN Shi-ping; LUO Chao

    2005-01-01

    In construction of high dams, design of a middle-pier, placed in a discharge tunnel to divide it into two parts, is a better choice that could breakthrough the limits of the manufacture and operation of the gate due to the high head to it. However, cavitation and water-wing, a kind of flow striking the top and side walls of the tunnel, induced by the middle-pier, may take place and bring about bad effects on operation of the tunnel. The experiments of the six comparing plans were conducted, consisting of atmospheric and vacuum tank models, and the interesting areas included relationships between discharges and reservoir levels, measurements of side wall pressures, comparisons of water-wing states for the various middle-piers, estimations of the incipient cavitation numbers and the flow cavitation numbers, and analyses of cavitation characteristics for the tunnel. A kind of new bodily form of middle-pier was developed. Water-wing states were better improved and non-cavitation conditions were satisfied.

  17. Investigating hydraulic connections and the origin of water in a mine tunnel using stable isotopes and hydrographs

    Energy Technology Data Exchange (ETDEWEB)

    Walton-Day, Katherine, E-mail: kwaltond@usgs.gov [US Geological Survey, Box 25046, MS 415, Denver, CO 80225 (United States); Poeter, Eileen [Department of Geology and Geological Engineering, Colorado School of Mines, Golden, CO 80401 (United States)

    2009-12-15

    Turquoise Lake is a water-supply reservoir located north of the historic Sugarloaf Mining district near Leadville, Colorado, USA. Elevated water levels in the reservoir may increase flow of low-quality water from abandoned mine tunnels in the Sugarloaf District and degrade water quality downstream. The objective of this study was to understand the sources of water to Dinero mine drainage tunnel and evaluate whether or not there was a direct hydrologic connection between Dinero mine tunnel and Turquoise Lake from late 2002 to early 2008. This study utilized hydrograph data from nearby draining mine tunnels and the lake, and stable isotope ({delta}{sup 18}O and {delta}{sup 2}H) data from the lake, nearby draining mine tunnels, imported water, and springs to characterize water sources in the study area. Hydrograph results indicate that flow from the Dinero mine tunnel decreased 26% (2006) and 10% (2007) when lake elevation (above mean sea level) decreased below approximately 3004 m (approximately 9855 feet). Results of isotope analysis delineated two meteoric water lines in the study area. One line characterizes surface water and water imported to the study area from the western side of the Continental Divide. The other line characterizes groundwater including draining mine tunnels, springs, and seeps. Isotope mixing calculations indicate that water from Turquoise Lake or seasonal groundwater recharge from snowmelt represents approximately 10% or less of the water in Dinero mine tunnel. However, most of the water in Dinero mine tunnel is from deep groundwater having minimal isotopic variation. The asymmetric shape of the Dinero mine tunnel hydrograph may indicate that a limited mine pool exists behind a collapse in the tunnel and attenutates seasonal recharge. Alternatively, a conceptual model is presented (and supported with MODFLOW simulations) that is consistent with current and previous data collected in the study area, and illustrates how fluctuating lake levels

  18. The possibility of drinking water capture for the city of Ljubljana by means of a water tunnel in the area of Krim mountain

    Directory of Open Access Journals (Sweden)

    Janko Urbanc

    2008-12-01

    Full Text Available The article deals with the possibility of groundwater capture by means of a groundwater drainage tunnel in the area of Krim mountain range for a supplementary water supply of the city of Ljubljana. Within the scope of the investigation, a detailed geological mapping of the area was carried out, and hydrogeological, geophysical andengineering-geological research was performed. A water balance of the recharge area was calculated, indicating considerable quantities of groundwater which could be captured with an underground drainage tunnel. A course of the tunnel was suggested, with its entrance part located on the southern fringes of Ljubljansko barje south ofthe village Strahomer. The tunnel would run in the south-west direction in the Upper Triassic dolomite. Because of low environmental burden in the recharge area of the tunnel and due to good cleaning properties of dolomite it is expected that drinking water of very good quality could be captured by means of the drainage tunnel.

  19. Analog modeling of pressurized subglacial water flow: Implications for tunnel valley formation and ice flow dynamics

    Science.gov (United States)

    Lelandais, Thomas; Ravier, Edouard; Mourgues, Régis; Pochat, Stéphane; Strzerzynski, Pierre; Bourgeois, Olivier

    2017-04-01

    Tunnel valleys are elongated and overdeepened depressions up to hundreds of kilometers long, several kilometers wide and hundreds of meters deep, found in formerly glaciated areas. These drainage features are interpreted as the result of subglacial meltwater erosion beneath ice sheets and constitute a major component of the subglacial drainage system. Although tunnel valleys have been described worldwide in the past decades, their formation is still a matter of debate. Here, we present an innovative experimental approach simulating pressurized water flow in a subglacial environment in order to study the erosional processes occurring at the ice-bed interface. We use a sandbox partially covered by a circular, viscous and transparent lid (silicon putty), simulating an impermeable ice cap. Punctual injection of pressurized water in the substratum at the center of the lid simulates meltwater production beneath the ice cap. Surface images collected by six synchronized cameras allow to monitor the evolution of the experiment through time, using photogrammetry methods and DEM generation. UV markers placed in the silicon are used to follow the silicon flow during the drainage of water at the substratum-lid interface, and give the unique opportunity to simultaneously follow the formation of tunnel valleys and the evolution of ice dynamics. When the water pressure is low, groundwater circulates within the substratum only and no drainage landforms appear at the lid-substratum interface. By contrast, when the water pressure exceeds a threshold that is larger than the sum of glaciostatic and lithostatic pressures, additional water circulation occurs at the lid-substratum interface and drainage landforms develop from the lid margin. These landforms share numerous morphological criteria with tunnel valleys such as undulating longitudinal profiles, U-shaped cross-sectional profiles with flat floors, constant widths and abrupt flanks. Continuous generation of DEMs and flow velocity

  20. Concerted hydrogen-bond breaking by quantum tunneling in the water hexamer prism.

    Science.gov (United States)

    Richardson, Jeremy O; Pérez, Cristóbal; Lobsiger, Simon; Reid, Adam A; Temelso, Berhane; Shields, George C; Kisiel, Zbigniew; Wales, David J; Pate, Brooks H; Althorpe, Stuart C

    2016-03-18

    The nature of the intermolecular forces between water molecules is the same in small hydrogen-bonded clusters as in the bulk. The rotational spectra of the clusters therefore give insight into the intermolecular forces present in liquid water and ice. The water hexamer is the smallest water cluster to support low-energy structures with branched three-dimensional hydrogen-bond networks, rather than cyclic two-dimensional topologies. Here we report measurements of splitting patterns in rotational transitions of the water hexamer prism, and we used quantum simulations to show that they result from geared and antigeared rotations of a pair of water molecules. Unlike previously reported tunneling motions in water clusters, the geared motion involves the concerted breaking of two hydrogen bonds. Similar types of motion may be feasible in interfacial and confined water.

  1. Model test of the tunnel subjected to high water pressure in Jinping Second Cascade Hydropower Station,China

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In the area with high groundwater pressure,grout curtain is often adopted to reduce the water pressure on tunnel lining.A series of model tests for the diversion tunnel of the Jinping Second Cascade Hydropower Station,China,is designed to study the effect of grout curtain.The impact of the thickness of grout curtain,permeability of grout curtain,internal water pressure and drainage inflow on the distribution of water pressure are discussed.The results indicates that under un-drained condition,water pressure is equal to hydrostatic one no matter grout curtain is selected or not,water pressure under drained condition is far less than that of un-drained condition,drainage in tunnel can reduce tunnel water pressure effectively.For same inflow,both increasing of thickness and decrease of hydraulic conductivity of grout curtain can reduce water pressure effectively.For the same water pressure,the smaller inflow of grout curtain,the less volume of water to be discharged.The impact of hydraulic conductivity of grout curtain is more obvious than that of thickness.With increasing of internal water pressure,the water pressure of grout curtain increases too,and the water pressure increases nearly linearly.The proposed thickness of grout curtain for the diversion tunnels is 16 m.

  2. Water tunnel flow visualization and wind tunnel data analysis of the F/A-18. [leading edge extension vortex effects

    Science.gov (United States)

    Erickson, G. E.

    1982-01-01

    Six degree of freedom studies were utilized to extract a band of yawing and rolling moment coefficients from the F/A-18 aircraft flight records. These were compared with 0.06 scale model data obtained in a 16T wind tunnel facility. The results, indicate the flight test yawing moment data exhibit an improvement over the wind tunnel data to near neutral stability and a significant reduction in lateral stability (again to anear neutral level). These data are consistent with the flight test results since the motion was characterized by a relatively slo departure. Flight tests repeated the slow yaw departure at M 0.3. Only 0.16 scale model wind tunnel data showed levels of lateral stability similar to the flight test results. Accordingly, geometric modifications were investigated on the 0.16 scale model in the 30x60 foot wind tunnel to improve high angle of attack lateral stability.

  3. Upper Bound Solution for the Face Stability of Shield Tunnel below the Water Table

    Directory of Open Access Journals (Sweden)

    Xilin Lu

    2014-01-01

    Full Text Available By FE simulation with Mohr-Coulomb perfect elastoplasticity model, the relationship between the support pressure and displacement of the shield tunnel face was obtained. According to the plastic strain distribution at collapse state, an appropriate failure mechanism was proposed for upper bound limit analysis, and the formula to calculate the limit support pressure was deduced. The limit support pressure was rearranged to be the summation of soil cohesion c, surcharge load q, and soil gravity γ multiplied by their corresponding coefficients Nc, Nq, and Nγ, and parametric studies were carried out on these coefficients. In order to consider the influence of seepage on the face stability, the pore water pressure distribution and the seepage force on the tunnel face were obtained by FE simulation. After adding the power of seepage force into the equation of the upper bound limit analysis, the total limit support pressure for stabilizing the tunnel face under seepage condition was obtained. The total limit support pressure was shown to increase almost linearly with the water table.

  4. Parallel Dynamic Analysis of a Large-Scale Water Conveyance Tunnel under Seismic Excitation Using ALE Finite-Element Method

    Directory of Open Access Journals (Sweden)

    Xiaoqing Wang

    2016-01-01

    Full Text Available Parallel analyses about the dynamic responses of a large-scale water conveyance tunnel under seismic excitation are presented in this paper. A full three-dimensional numerical model considering the water-tunnel-soil coupling is established and adopted to investigate the tunnel’s dynamic responses. The movement and sloshing of the internal water are simulated using the multi-material Arbitrary Lagrangian Eulerian (ALE method. Nonlinear fluid–structure interaction (FSI between tunnel and inner water is treated by using the penalty method. Nonlinear soil-structure interaction (SSI between soil and tunnel is dealt with by using the surface to surface contact algorithm. To overcome computing power limitations and to deal with such a large-scale calculation, a parallel algorithm based on the modified recursive coordinate bisection (MRCB considering the balance of SSI and FSI loads is proposed and used. The whole simulation is accomplished on Dawning 5000 A using the proposed MRCB based parallel algorithm optimized to run on supercomputers. The simulation model and the proposed approaches are validated by comparison with the added mass method. Dynamic responses of the tunnel are analyzed and the parallelism is discussed. Besides, factors affecting the dynamic responses are investigated. Better speedup and parallel efficiency show the scalability of the parallel method and the analysis results can be used to aid in the design of water conveyance tunnels.

  5. Evolution Characteristic Analysis of Pressure-arch of a Double-arch Tunnel in Water-rich Strata

    Directory of Open Access Journals (Sweden)

    C. L. Li

    2016-03-01

    Full Text Available It is of importance to analyze the morphological characterization, the evolution process and the skewed effect of pressure-arch of a double-arch tunnel in the water-rich strata. Taking a buried depth 80 m double-arch tunnel as an example, a computational model of the double-arch tunnel was built by using FLAC3D technique. Then considering some aspects including groundwater conditions, tunnel depth, construction sequences and permeability coefficients, the coupling effect of stress field and seepage field in the pressure-arch of the double-arch tunnel was analyzed. The results show that the thickness of the pressure-arch induced by step-by-step excavation and display a step-descent skewed distribution from the left to the right of the double-arch tunnel. The permeability coefficient has a significant influence on the shape and the skewed effect of the pressure arch. The excavation of the bench method has a better arching condition than that of the expanding method. The abtained results provide a basic reference for the rock reinforcement design and safety construction of double-arch tunnels in the water-rich strata.

  6. Protection against water or mud inrush in tunnels by grouting: A review

    Directory of Open Access Journals (Sweden)

    Shucai Li

    2016-10-01

    Full Text Available Grouting is a major method used to prevent water and mud inrush in tunnels and underground engineering. In this paper, the current situation of control and prevention of water and mud inrush is summarized and recent advances in relevant theories, grout/equipment, and critical techniques are introduced. The time-variant equations of grout viscosity at different volumetric ratios were obtained based on the constitutive relation of typical fast curing grouts. A large-scale dynamic grouting model testing system (4000 mm × 2000 mm × 5 mm was developed, and the diffusions of cement and fast curing grouts in dynamic water grouting were investigated. The results reveal that the diffusions of cement grouts and fast curing grouts are U-shaped and asymmetric elliptical, respectively. A multi-parameter real-time monitoring system (ϕ = 1.5 m, h = 1.2 m was developed for the grouting process to study the diffusion and reinforcement mechanism of grouting in water-rich faulted zone. A high early strength cream-type reinforcing/plugging grout, a high permeability nano-scale silica gel grout, and a high-expansion filling grout were proposed for the control of water hazards in weak water-rich faulted zone rocks, water inrush in karst passages, and micro-crack water inrush, respectively. Complement technologies and equipment for industrial applications were also proposed. Additionally, a novel full-life periodic dynamic water grouting with the critical grouting borehole as the core was proposed. The key techniques for the control of water inrush in water-rich faulted zone, jointed fissures and karst passages, and micro-crack water inrush were developed.

  7. An apparatus to estimate the hydrodynamic coefficients of autonomous underwater vehicles using water tunnel testing

    Science.gov (United States)

    Nouri, N. M.; Mostafapour, K.; Bahadori, R.

    2016-06-01

    Hydrodynamic coefficients or hydrodynamic derivatives of autonomous underwater vehicles (AUVs) play an important role in their development and maneuverability. The most popular way of estimating their coefficients is to implement captive model tests such as straight line tests and planar motion mechanism (PMM) tests in the towing tanks. This paper aims to develop an apparatus based on planar experiments of water tunnel in order to estimate hydrodynamic derivatives due to AUVs' acceleration and velocity. The capability of implementing straight line tests and PMM ones using mechanical oscillators located in the downstream flow of the model is considered in the design procedure of the system. The hydrodynamic derivatives that resulted from the acceleration and velocity of the AUV model were estimated using the apparatus that we developed. Static and dynamics test results were compared for the similar derivatives. The findings showed that the system provided the basis for conducting static tests, i.e., straight-line and dynamic tests that included pure pitch and pure heave. By conducting such tests in a water tunnel, we were able to eliminate errors related to the time limitation of the tests and the effects of surface waves in the towing tank on AUVs with applications in the deep sea.

  8. Aerodynamic control of NASP-type vehicles through Vortex manipulation. Volume 1: Static water tunnel tests

    Science.gov (United States)

    Suarez, Carlos J.; Ng, T. Terry; Ong, Lih-Yenn; Malcolm, Gerald N.

    1993-01-01

    Water tunnel tests were conducted on a NASP-type configuration to evaluate different pneumatic Forebody Vortex Control (FVC) methods. Flow visualization and yawing moment measurements were performed at angles of attack from 0 deg to 30 deg. The pneumatic techniques tested included jet and slot blowing. In general, blowing can be used efficiently to manipulate the forebody vortices at angles of attack greater than 20 deg. These vortices are naturally symmetric up to alpha = 25 deg and asymmetric between 25 deg and 30 deg angle of attack. Results indicate that tangential aft jet blowing is the most promising method for this configuration. Aft jet blowing produces a yawing moment towards the blowing side and the trends with blowing rate are well behaved. The size of the nozzle is not the dominant factor in the blowing process; the change in the blowing 'momentum,' i.e., the product of the mass flow rate and the velocity of the jet, appears to be the important parameter in the water tunnel (incompressible and unchoked flow at the nozzle exit). Forward jet blowing is very unpredictable and sensitive to mass flow rate changes. Slot blowing (with the exception of very low blowing rates) acts as a flow 'separator'; it promotes early separation on the blow side, producing a yawing moment toward the non-blowing side for the C(sub mu) range investigated.

  9. Space shuttle orbiter flow visualization study. [water tunnel study of vortex flow during atmospheric entry

    Science.gov (United States)

    Lorincz, D. J.

    1980-01-01

    The vortex flows generated at subsonic speed during the final portion of atmospheric reentry were defined using a 0.01 scale model of the orbiter in a diagnostic water tunnel. Flow visualization photographs were obtained over an angle-of-attack range to 40 deg and sideslip angles up to 10 deg. The vortex flow field development, vortex path, and vortex breakdown characteristics were determined as a function of angle-of-attack at zero sideslip. Vortex flows were found to develop on the highly swept glove, on the wing, and on the upper surface of the fuselage. No significant asymmetries were observed at zero sideslip in the water tunnel tests. The sensitivity of the upper surface vortex flow fields to variations in sideslip angle was also studied. The vortex formed on the glove remained very stable in position above the wing up through the 10 deg of sideslip tested. There was a change in the vortex lifts under sideslip due to effective change in leading-edge sweep angles. Asymmetric flow separation occurred on the upper surface of the fuselage at small sideslip angles. The influence of vortex flow fields in sideslip on the lateral/ directional characteristics of the orbiter is discussed.

  10. Loetschberg low-level tunnel: thermal use of tunnel water at the south portal - Feasibility study, phase II; Waermenutzung Tunnelwasser Basistunnel Loetschberg, Suedportal. Machbarkeitsstudie Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Dups, Ch.

    2004-07-01

    This report for the Swiss Federal Office of Energy (SFOE) discusses the results obtained from phase II of a feasibility study on the thermal use of drainage water from the Loetschberg basis railway tunnel under the Swiss Alps. The potential for the use of the drainage water is discussed and the possible use of the heat in the industrial estates in Raron and Niedergesteln is looked at. The report recommends the further investigation of the use of the water as a source of heat for heat-pumps and its treatment for further use as drinking water. Other possible uses examined include the heating of greenhouses, in fish farms, as a water supply for a gravel and concrete works and for keeping local roads and motorways frost-free.

  11. Study of tunnelling through water-bearing fracture zones. Baseline study on technical issues with NE-1 as reference

    Energy Technology Data Exchange (ETDEWEB)

    Yanting Chang; Swindell, Robert; Bogdanoff, Ingvar; Lindstroem, Beatrice; Termen, Jens [WSP Sweden, Stockholm (Sweden) ; Starsec, Peter [SGI, Linkoeping (Sweden)

    2005-04-01

    The Swedish Nuclear Fuel and Waste Management Co (SKB) is responsible for the management of Sweden's nuclear waste. SKB is investigating various designs for the construction of an underground deep repository for spent nuclear fuel at 500-600 m depths. For the construction of an access tunnel for such a deep repository, the possibility of encountering a water-bearing fracture zone cannot be discounted. Such a zone named NE-1 (deformation zone in accordance to SKB's terminology) was encountered during the construction of the Aespoe Hard Rock Laboratory (HRL) and difficulties with large water inflows were reported. With the aim to assess the feasibility of different technical solutions, SKB commissioned a baseline study into the passage of an access tunnel through a water-bearing fracture zone at three different depths (200 m, 400 m and 600 m). The objectives of this baseline study are to: Increase the knowledge of possible technical solutions for tunnelling through water-bearing fractures zones with the characteristics of the brittle deformation zone NE-1 at different depths, namely 200, 400 and 600 metres; Form a reference document to assist the engineering design and construction work for the passage through such a water-bearing fracture zone; To highlight the engineering parameters that should be obtained to facilitate design for the passage through water-bearing fracture zones.The study has been carried out in the following five stages: A. Compilation of the relevant data for deformation zone NE-1; B. Problem identification and proposal of technical solutions; C. Identification of hazards to be involved in the tunnel excavation; D. Recommendations and conclusions for further investigations; E. Documentation of the results in a final report. The analyses will be expressed in statistical/probabilistic terms where appropriate. In order to specify the precondition that will be valid for this study, a descriptive model of the water-bearing fracture zone is

  12. Treatment of tunnel wash waters - experiments with organic sorbent materials. Part I: Removal of polycyclic aromatic hydrocarbons and nonpolar oil

    Institute of Scientific and Technical Information of China (English)

    PARUCH AdamM; ROSETH Roger

    2008-01-01

    Tunnel wash waters characterize all waters that run off after washing procedures of tunnels are performed. These waters represent a wide spectrum of organic and inorganic pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and toxic metals. Removal of such contaminants from water runoff was investigated using laboratory tests after washing procedure was performed on two road tunnels in eastern Norway (Hanekleiv and Bragernes). Due to diverse character of both, treatment media and treated wash waters, the whole investigation was divided into two separate laboratory experiments. The treatment efficiencies were established based on the levels of concentrations and reductions of the measured contaminants in the effluents released from the tested media. In the first part of the article, the contents of nonpolar oil (NPO), 16 individual PAHs, and total PAHs (∑PAH16) are described. This part revealed that the combination of two organic sorbent materials provided the highest treatment efficiency for wash waters released from the road tunnel and from electrostatic filters. The greatest reduction levels reached 97.6% for NPO, 97.2% for benzo[a]pyrene, and 96.5% for the total PAHs. In the second part of the article, the concentrations and the removal rates of toxic metals are reported

  13. Effect of localized water uptake on backfill hydration and water movement in a backfilled tunnel: half-scale tests at Aespoe Bentonite Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, D. [Atomic Energy of Canada Limited, Chalk River (Canada); Jonsson, E. [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Hansen, J. [Posiva Oy, Olkiluoto (Finland); Hedin, M. [Aangpannefoereningen, Stockholm (Sweden); Ramqvist, G. [Eltekno AB, Figeholm (Sweden)

    2011-04-15

    The report describes the outcome of the work within the project 'SU508.20 Impact of water inflow in deposition tunnels'. Project decision SKB doc 1178871 Version 3.0. Two activity plans have been used for the field work: AP TD SU50820-09-019 and AP TD SU 50820-09-071. SKB and Posiva have been examining those processes that may have particularly strong effects on the evolution of a newly backfilled deposition tunnel in a KBS-3V repository. These assessments have involved the conduct of increasingly large and complex laboratory tests and simulations of a backfilled tunnel section. In this series of four tests, the effect of water inflow into a backfilled tunnel section via an intersecting fracture feature was evaluated. The tests included the monitoring of mock-ups where water entered via the simulated fractures as well as evaluation of what the effect of isolated tunnel sections caused by localized water inflow would have on subsequent evolution of these isolated sections. It was found that even a slowly seeping fracture can have a substantial effect on the backfill evolution as it will cause development of a gasket-like feature that effectively cuts of air and water movement from inner to outer regions of the backfilled tunnel. Water entering via these fractures will ultimately move out of the tunnel via a single discrete flow path, in a manner similar to what was observed in previous 1/2-scale and smaller simulations. If the low-rate of water inflow from fracture is the only source of water inflow to the tunnel this will result in hydraulic behaviour similar to that observed for a single inflow point in previous tests. The presence of a fracture feature will however result in a larger proportion of water uptake by the process of suction than might occur in a point inflow situation and hence a more uniform water distribution will be present in the pellet fill. This also results in a greater tendency for water to be absorbed into the adjacent block fill

  14. Treatment of tunnel wash waters--experiments with organic sorbent materials. Part II: Removal of toxic metals.

    Science.gov (United States)

    Paruch, Adam M; Roseth, Roger

    2008-01-01

    In the first part of the article, the column and the bag experiments concerning removal of polycyclic aromatic hydrocarbons (PAHs) and nonpolar oil (NPO) from tunnel wash waters using organic sorbent materials have been described. This part presents the results of removal of toxic metals. The metals of concern (Al, As, Cd, Cr, Cu, Fe, Pb, Mo, Ni, and Zn) were selected based on the priority toxicant pollutants defined in surface water quality criteria. Concentrations of these metals in the collected effluents varied more than the concentrations of PAHs and NPO, and thus only metal contents were considered for statistical analyses. These analyses determined significant differences (P experiments revealed that the organic sorbents, and in particular their combination, removed toxic metals more effectively from wash water of road tunnel than from wash water of tunnel electrostatic filters. Among the investigated toxicants, Al and Fe showed the highest levels of reduction in the column experiment, 99.7% and 99.6%, respectively. The lowest reduction levels of 66.0% and 76.2% were found for Pb and Mo, respectively. The results of the bag experiment showed that even one day treatment of wash waters from tunnel electrostatic filters could reduce concentration of some toxicants by more than 70% (Al and Fe) and 80% (Cu).

  15. Failure Mode of the Water-filled Fractures under Hydraulic Pressure in Karst Tunnels

    Science.gov (United States)

    Dong, Xin; Lu, Hao; Huang, Houxu; Hao, Yiqing; Xia, Yuanpu

    2017-06-01

    Water-filled fractures continue to grow after the excavation of karst tunnels, and the hydraulic pressure in these fractures changes along with such growth. This paper simplifies the fractures in the surrounding rock as flat ellipses and then identifies the critical hydraulic pressure values required for the occurrence of tensile-shear and compression-shear failures in water-filled fractures in the case of plane stress. The occurrence of tensile-shear fracture requires a larger critical hydraulic pressure than compression-shear failure in the same fracture. This paper examines the effects of fracture strike and lateral pressure coefficient on critical hydraulic pressure, and identifies compression-shear failure as the main failure mode of water-filled fractures. This paper also analyses the hydraulic pressure distribution in fractures with different extensions, and reveals that hydraulic pressure decreases along with the continuous growth of fractures and cannot completely fill a newly formed fracture with water. Fracture growth may be interrupted under the effect of hydraulic tensile shear.

  16. Failure Mode of the Water-filled Fractures under Hydraulic Pressure in Karst Tunnels

    Directory of Open Access Journals (Sweden)

    Dong Xin

    2017-06-01

    Full Text Available Water-filled fractures continue to grow after the excavation of karst tunnels, and the hydraulic pressure in these fractures changes along with such growth. This paper simplifies the fractures in the surrounding rock as flat ellipses and then identifies the critical hydraulic pressure values required for the occurrence of tensile-shear and compression-shear failures in water-filled fractures in the case of plane stress. The occurrence of tensile-shear fracture requires a larger critical hydraulic pressure than compression-shear failure in the same fracture. This paper examines the effects of fracture strike and lateral pressure coefficient on critical hydraulic pressure, and identifies compression-shear failure as the main failure mode of water-filled fractures. This paper also analyses the hydraulic pressure distribution in fractures with different extensions, and reveals that hydraulic pressure decreases along with the continuous growth of fractures and cannot completely fill a newly formed fracture with water. Fracture growth may be interrupted under the effect of hydraulic tensile shear.

  17. Water tunnel visualization of the vortex flows of the F-15

    Science.gov (United States)

    Lorincz, D. J.; Friend, E. L.

    1979-01-01

    Flow visualization studies were conducted in a diagnostic water tunnel to provide details of the wing, glove, and forebody vortex flow fields of the F-15 aircraft over a range of angles of attack and sideslip. Both the formation and breakdown of the vortex flow as a function of angle of attack and sideslip are detailed for the basic aircraft configuration. Additional tests showed that the wing upper surface vortex flows were sensitive to variations in an inlet mass flow ratio and an inlet cowl deflection angle. Two lengthened forebodies, one with a modified cross-sectional shape, were tested in addition to the basic forebody. Asymmetric forebody vortices were observed at zero sideslip and high angles of attack on each forebody. A large nose boom was added to each of the three forebodies, and it was observed that the turbulent wake shed from the boom disrupted the forebody vortices.

  18. Forecasting and prevention of water inrush during the excavation process of a diversion tunnel at the Jinping II Hydropower Station, China.

    Science.gov (United States)

    Hou, Tian-Xing; Yang, Xing-Guo; Xing, Hui-Ge; Huang, Kang-Xin; Zhou, Jia-Wen

    2016-01-01

    Estimating groundwater inflow into a tunnel before and during the excavation process is an important task to ensure the safety and schedule during the underground construction process. Here we report a case of the forecasting and prevention of water inrush at the Jinping II Hydropower Station diversion tunnel groups during the excavation process. The diversion tunnel groups are located in mountains and valleys, and with high water pressure head. Three forecasting methods are used to predict the total water inflow of the #2 diversion tunnel. Furthermore, based on the accurate estimation of the water inrush around the tunnel working area, a theoretical method is presented to forecast the water inflow at the working area during the excavation process. The simulated results show that the total water flow is 1586.9, 1309.4 and 2070.2 m(3)/h using the Qshima method, Kostyakov method and Ochiai method, respectively. The Qshima method is the best one because it most closely matches the monitoring result. According to the huge water inflow into the #2 diversion tunnel, reasonable drainage measures are arranged to prevent the potential disaster of water inrush. The groundwater pressure head can be determined using the water flow velocity from the advancing holes; then, the groundwater pressure head can be used to predict the possible water inflow. The simulated results show that the groundwater pressure head and water inflow re stable and relatively small around the region of the intact rock mass, but there is a sudden change around the fault region with a large water inflow and groundwater pressure head. Different countermeasures are adopted to prevent water inrush disasters during the tunnel excavation process. Reasonable forecasting the characteristic parameters of water inrush is very useful for the formation of prevention and mitigation schemes during the tunnel excavation process.

  19. Tunnelling and barrier-less motions in the 2-fluoroethanol-water complex: a rotational spectroscopic and ab initio study.

    Science.gov (United States)

    Huang, Wenyuan; Thomas, Javix; Jäger, Wolfgang; Xu, Yunjie

    2017-05-17

    The pure rotational spectrum of the 2-fluoroethanol (2-FE)water complex was measured using a chirped pulse Fourier-transform microwave spectrometer and a cavity-based Fourier-transform microwave spectrometer. In the detected 2-FEwater conformer, 2-FE serves as a proton donor, in contrast to its role in the observed ethanolwater conformer, while water acts simultaneously as a hydrogen bond donor and acceptor, forming a hydrogen-bonded ring with an OHO and an OHF hydrogen bond. Comparison to the calculated dipole moment components suggests that the observed structure sits between the two most stable minima identified theoretically. This conclusion is supported by extensive deuterium isotopic data. Further analysis shows that these two minima are connected by a barrier-less wagging motion of the non-bonded hydrogen of the water subunit. The observed narrow splitting with a characteristic 3 : 1 intensity ratio is attributed to an exchange of the bonded and non-bonded hydrogen atoms of water. The tunneling barrier of a proposed tunneling path is calculated to be as low as 5.10 kJ mol(-1). A non-covalent interaction analysis indicates that the water rotation motion along the tunneling path has a surprisingly small effect on the interaction energy between water and 2-FE.

  20. WATER TUNNEL EXPERIMENTAL INVESTIGATION ON THE DRAG REDUCTION CHARACTERISTICS OF THE TRAVELING WAVY WALL

    Institute of Scientific and Technical Information of China (English)

    YAO Yan; LU Chuan-jing; SI Ting; ZHU Kun

    2011-01-01

    Drag reduction experiment of the traveling wavy wall at high Reynolds number is conducted. A suit of traveling wavy wall device is developed. The drag forces of the traveling wavy wall with various wave speeds ( c ) are measured under different water speeds (U) in the K15 cavitation water tunnel and are compared with that of the flat plate. The results show that the mean drag force of the traveling wavy wall have decreased and then increased with oscillation frequency increasing at the same flow speed.Under different flow speeds, when traveling wave wall reached to the minimum of drag force, the corresponding the ratio of the wall motion phase speed c to flow speed U, c/U is slightly different. Within the parameters of the experiment, when c/U reaches a certain value, the drag force of the traveling wavy wall can be less than that of the flat plate. The drag reduction can be up to 42%.Furthermore, as the value of c / U increases, the traveling wavy wall can restrain the separation and improve the quality of flow field.

  1. The evaporation of the charged and uncharged water drops suspended in a wind tunnel

    Indian Academy of Sciences (India)

    Rohini V Bhalwankar; A B Sathe; A K Kamra

    2004-06-01

    A laboratory experiment has been performed to study the effect of ventilation on the rate of evaporation of the millimeter sized charged and uncharged water drops suspended in a vertical wind tunnel. The linear relationship, = 0.907 + 0.282 , observed between the mean ventilation coefficient, , and a non-dimensional parameter , ( = $N^{1/3}_{Sc,v} N^{1/2}_{Re}$ where Sc,v is Schmidt number and Re is Reynold's number) is in agreement with the results of earlier investigations for uncharged water drops. However, in case of charged drops carrying 10−10C of charge, this relationship gets modified to = 0.4877 + 0.149. Thus, the rate of evaporation of charged drops is slower than that of uncharged drops of the same size. Oscillations of the drop and the change in airflow around drops are suggested to contribute to lowering of the ventilation coefficients for charged drops. Applicability of the results to a small fraction of highly charged raindrops falling through the sub-cloud layer below thunderstorm is discussed. The relaxation time required for a ventilated drop to reach its equilibrium temperature increases with the drop size and is higher for the charged than for the uncharged drops. It is concluded that in a given distance, charged drops will evaporate less than that of uncharged drops.

  2. A Technique for Measurement of Static and Dynamic Longitudinal Aerodynamic Derivatives Using the DSTO Water Tunnel

    Science.gov (United States)

    2011-12-01

    deformed models in straight air streams as discussed by Gorlin and Slezinger [9]. Otherwise, wind tunnel experimental methods are generally based on...1945. 9. Gorlin , S. M., and Slezinger, I. I., Wind Tunnels and Their Instrumentation (Aeromekhanicheskie izmerenia. Metody i pribory), trans. P

  3. Water tunnel results of leading-edge vortex flap tests on a delta wing vehicle

    Science.gov (United States)

    Delfrate, J. H.

    1986-01-01

    A water tunnel flow visualization test on leading edge vortex flaps was conducted at the flow visualization facility of the NASA Ames Research Center's Dryden Flight Research Facility. The purpose of the test was to visually examine the vortex structures caused by various leading edge vortex flaps on the delta wing of an F-106 model. The vortex flaps tested were designed analytically and empirically at the NASA Langley Research Center. The three flap designs were designated as full-span gothic flap, full-span untapered flap, and part-span flap. The test was conducted at a Reynolds number of 76,000/m (25,000/ft). This low Reynolds number was used because of the 0.076-m/s (0.25-ft/s) test section flow speed necessary for high quality flow visualization. However, this low Reynolds number may have influenced the results. Of the three vortex flaps tested, the part-span flap produced what appeared to be the strongest vortex structure over the flap area. The full-span gothic flap provided the next best performance.

  4. 高水位隧道衬砌临界水头数值计算%Numerical Calculation of High Water Head Tunnel on Critical Water Pressure

    Institute of Scientific and Technical Information of China (English)

    郑波; 吴剑; 王建宇

    2015-01-01

    Two kinds of typical tunnel section is chosen for analyzing the critical water pressure of high water head tunnel by numerical calculation method.The calculation results show that:①for the design speed 250 km/h double-line tunnel, when the lining thickness is respectively 30 cm, 50 cm, plain concrete lining is not liable for any water pressure load, and C30 reinforced concrete lining can bear respectively 11.2 m, 34.2 m water head load;②for the design speed 200 km/h single track railway tunnel, when the lining thickness is respectively 30 cm, 50 cm, 60 cm, plain concrete lining can bear respectively 0 m, 1 m, 5.5 m, and C30 reinforced concrete lin-ing can bear respectively 26 m, 55.2 m, 73.5 m water head load;③the tunnel shape has great influence on criti-cal water head, single-track railway tunnel can bear greater critical water pressure than double-track tunnel;④for high water head tunnel, according to new concept of water control in tunnel, the amount of water inflow should be limited.%选取2种典型隧道断面,对其所能承受的极限水头值进行分析。计算结果表明:①对设计时速250 km/h的客专双线隧道,当衬砌厚度分别为t=30 cm、50 cm时,素混凝土衬砌均不能承担任何水压力荷载,C30钢筋混凝土衬砌能承受的极限水位分别为11.2 m、34.2 m;②对设计时速200 km/h的单线铁路隧道,当衬砌厚度分别为30 cm、50 cm、60 cm时,素混凝土衬砌能承受的极限水头分别为0 m、1.0 m、5.5 m,C30钢筋混凝土衬砌能承受的极限水头分别为26.0 m、55.2 m、73.5 m;③隧道形状对所承受的极限水头值有较大的影响,单线铁路隧道比客专双线隧道更有利于承受水压力;④对于高水位隧道,应该采取“以堵为主,限量排放”的措施,降低衬砌水压力,使设计既安全又经济。

  5. A water tunnel flow visualization study of the vortex flow structures on the F/A-18 aircraft

    Science.gov (United States)

    Sandlin, Doral R.; Ramirez, Edgar J.

    1991-01-01

    The vortex flow structures occurring on the F/A-18 aircraft at high angles of attack were studied. A water tunnel was used to gather flow visualization data on the forebody vortex and the wing leading edge extension vortex. The longitudinal location of breakdown of the leading edge vortex was found to be consistently dependent on the angle of attack. Other parameters such as Reynolds number, model scale, and model fidelity had little influence on the overall behavior of the flow structures studied. The lateral location of the forebody vortex system was greatly influenced by changes in the angle of sideslip. Strong interactions can occur between the leading edge extension vortex and the forebody vortex. Close attention was paid to vortex induced flows on various airframe components of the F/A-18. Reynolds number and angle of attack greatly affected the swirling intensity, and therefore the strength of the studied vortices. Water tunnel results on the F/A-18 correlated well with those obtained in similar studies at both full and sub scale levels. The water tunnel can provide, under certain conditions, good simulations of realistic flows in full scale configurations.

  6. Drainage water use from the railway Mont d'Or tunnel in Vallorbe, Switzerland; Centrale du Bief-Rouge. Recuperation des eaux du tunnel du Mont d'Or a Vallorbe - Rapport 2009

    Energy Technology Data Exchange (ETDEWEB)

    Gerodetti, M.

    2009-02-15

    The 6'097 m long Railway Tunnel under the Mont d'Or (western Switzerland, under the Jura mountains) was constructed at the beginning of the 20{sup th} century and inaugurated on 16 May 1915. During the construction there was an important break-in of water in the tunnel that flooded the whole construction area. Since the completion of the tunnel, the water incursion is drained and conveyed to the Swiss entrance. The flow rate coming from the tunnel is constant at about 120 l/s and didn't show any variation during all the past decades. The idea of using the tunnel water energy in a turbine is thought of since a long time. Considering the present situation on the energy sector, the 'Societe electrique du Chatelard' (the local electricity utility) with the support of the municipal authority, decided now to realize this concept and to turbine the water from the tunnel, also known as 'Bief Rouge', for power generation. The 'Bief Rouge' project consists in catching the flow at the Vallorbe entrance of the tunnel and conducting it into a new penstock down to the river Orbe situated some 65 m downhill where electricity will be produced in a new small-scale power plant. The planned scheme will have an electrical power of 54.5 kW and be located in a new building near the existing sewage pumping station of Vallorbe. The total investment cost is 1.3 million CHF and includes the construction of a new headwater basin, a penstock, a power plant and a tailrace channel as well as the electro-mechanical equipment for power production. Based on a mean annual power production of some 465,000 kWh, the retail price of the kWh has been evaluated to 21 Swiss cents/kWh. (author)

  7. Detecting and monitoring of water inrush in tunnels and coal mines using direct current resistivity method:A review

    Institute of Scientific and Technical Information of China (English)

    Shucai Li; Bin Liu; Lichao Nie; Zhengyu Liu; Mingzhen Tian; Shirui Wang; Maoxin Su; Qian Guo

    2015-01-01

    Detecting, real-time monitoring and early warning of underground water-bearing structures are critically important issues in prevention and mitigation of water inrush hazards in underground engineering. Direct current (DC) resistivity method is a widely used method for routine detection, advanced detection and real-time monitoring of water-bearing structures, due to its high sensitivity to groundwater. In this study, the DC resistivity method applied to underground engineering is reviewed and discussed, including the observation mode, multiple inversions, and real-time monitoring. It is shown that a priori information constrained inversion is desirable to reduce the non-uniqueness of inversion, with which the accuracy of detection can be significantly improved. The focused resistivity method is prospective for advanced detection;with this method, the flanking interference can be reduced and the detection dis-tance is increased subsequently. The time-lapse resistivity inversion method is suitable for the regions with continuous conductivity changes, and it can be used to monitor water inrush in those regions. Based on above-mentioned features of various methods in terms of benefits and limitations, we propose a three-dimensional (3D) induced polarization method characterized with multi-electrode array, and introduce it into tunnels and mines combining with real-time monitoring with time-lapse inversion and cross-hole resistivity method. At last, the prospective applications of DC resistivity method are discussed as follows: (1) available advanced detection technology and instrument in tunnel excavated by tunnel boring machine (TBM), (2) high-resolution detection method in holes, (3) four-dimensional (4D) monitoring technology for water inrush sources, and (4) estimation of water volume in water-bearing structures.

  8. Detecting and monitoring of water inrush in tunnels and coal mines using direct current resistivity method: A review

    Directory of Open Access Journals (Sweden)

    Shucai Li

    2015-08-01

    Full Text Available Detecting, real-time monitoring and early warning of underground water-bearing structures are critically important issues in prevention and mitigation of water inrush hazards in underground engineering. Direct current (DC resistivity method is a widely used method for routine detection, advanced detection and real-time monitoring of water-bearing structures, due to its high sensitivity to groundwater. In this study, the DC resistivity method applied to underground engineering is reviewed and discussed, including the observation mode, multiple inversions, and real-time monitoring. It is shown that a priori information constrained inversion is desirable to reduce the non-uniqueness of inversion, with which the accuracy of detection can be significantly improved. The focused resistivity method is prospective for advanced detection; with this method, the flanking interference can be reduced and the detection distance is increased subsequently. The time-lapse resistivity inversion method is suitable for the regions with continuous conductivity changes, and it can be used to monitor water inrush in those regions. Based on above-mentioned features of various methods in terms of benefits and limitations, we propose a three-dimensional (3D induced polarization method characterized with multi-electrode array, and introduce it into tunnels and mines combining with real-time monitoring with time-lapse inversion and cross-hole resistivity method. At last, the prospective applications of DC resistivity method are discussed as follows: (1 available advanced detection technology and instrument in tunnel excavated by tunnel boring machine (TBM, (2 high-resolution detection method in holes, (3 four-dimensional (4D monitoring technology for water inrush sources, and (4 estimation of water volume in water-bearing structures.

  9. A 1:8.7 Scale Water Tunnel Verification & Validation Test of an Axial Flow Water Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Fontaine, Arnold A. [Pennsylvania State Univ., University Park, PA (United States); Straka, William A. [Pennsylvania State Univ., University Park, PA (United States); Meyer, Richard S. [Pennsylvania State Univ., University Park, PA (United States); Jonson, Michael L. [Pennsylvania State Univ., University Park, PA (United States)

    2014-09-01

    As interest in waterpower technologies has increased over the last few years, there has been a growing need for a public database of measured data for these devices. This would provide a basic understanding of the technology and means to validate analytic and numerical models. Through collaboration between Sandia National Laboratories, Penn State University Applied Research Laboratory, and University of California, Davis, a new marine hydrokinetic turbine rotor was designed, fabricated at 1:8.7-scale, and experimentally tested to provide an open platform and dataset for further study and development. The water tunnel test of this three-bladed, horizontal-axis rotor recorded power production, blade loading, near-wake characterization, cavitation effects, and noise generation. This report documents the small-scale model test in detail and provides a brief discussion of the rotor design and an initial look at the results with comparison against low-order modeling tools. Detailed geometry and experimental measurements are released to Sandia National Laboratories as a data report addendum.

  10. Formation of the prebiotic molecule NH$_2$CHO on astronomical amorphous solid water surfaces: accurate tunneling rate calculations

    CERN Document Server

    Song, Lei

    2016-01-01

    Investigating how formamide forms in the interstellar medium is a hot topic in astrochemistry, which can contribute to our understanding of the origin of life on Earth. We have constructed a QM/MM model to simulate the hydrogenation of isocyanic acid on amorphous solid water surfaces to form formamide. The binding energy of HNCO on the ASW surface varies significantly between different binding sites, we found values between $\\sim$0 and 100 kJ mol$^{-1}$. The barrier for the hydrogenation reaction is almost independent of the binding energy, though. We calculated tunneling rate constants of H + HNCO $\\rightarrow$ NH$_2$CO at temperatures down to 103 K combining QM/MM with instanton theory. Tunneling dominates the reaction at such low temperatures. The tunneling reaction is hardly accelerated by the amorphous solid water surface compared to the gas phase for this system, even though the activation energy of the surface reaction is lower than the one of the gas-phase reaction. Both the height and width of the ba...

  11. Actinide Sorption in Rainier Mesa Tunnel Waters from the Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, P; Zavarin, M; Leif, R; Powell, B; Singleton, M; Lindvall, R; Kersting, A

    2007-12-17

    The sorption behavior of americium (Am), plutonium (Pu), neptunium (Np), and uranium (U) in perched Rainier Mesa tunnel water was investigated. Both volcanic zeolitized tuff samples and groundwater samples were collected from Rainier Mesa, Nevada Test Site, NV for a series of batch sorption experiments. Sorption in groundwater with and without the presence of dissolved organic matter (DOM) was investigated. Am(III) and Pu(IV) are more soluble in groundwater that has high concentrations of DOM. The sorption K{sub d} for Am(III) and Pu(IV) on volcanic zeolitized tuff was up to two orders of magnitude lower in samples with high DOM (15 to 19 mg C/L) compared to samples with DOM removed (< 0.4 mg C/L) or samples with naturally low DOM (0.2 mg C/L). In contrast, Np(V) and U(VI) sorption to zeolitized tuff was much less affected by the presence of DOM. The Np(V) and U(VI) sorption Kds were low under all conditions. Importantly, the DOM was not found to significantly sorb to the zeolitized tuff during these experiment. The concentration of DOM in groundwater affects the transport behavior of actinides in the subsurface. The mobility of Am(III) and Pu(IV) is significantly higher in groundwater with elevated levels of DOM resulting in potentially enhanced transport. To accurately model the transport behavior of actinides in groundwater at Rainier Mesa, the low actinide Kd values measured in groundwater with high DOM concentrations must be incorporated in predictive transport models.

  12. Liquid water content measurements using the Phase Doppler Particle Analyzer in the NASA Lewis Icing Research Tunnel

    Science.gov (United States)

    Rudoff, R. C.; Bachalo, E. J.; Bachalo, W. D.; Oldenburg, J. R.

    1993-01-01

    The performance of a Phase Doppler Particle Analyzer (PDPA) based icing probe suitable for use in icing tunnels and airborne applications is assessed. The instrument is shown to accurately and repeatably measure liquid water content (LWC) to within better than 20 percent of the nominal expected value in the NASA Lewis IRT. This was seen to be true over a wide range of tunnel operating conditions. The principles used by the PDPA for MVD and LWC determination are discussed. Calibration curves for the IRT median volume diameter are also determined and compared to the existing calibration determined via the PMS instruments. As has been shown in previous work, the PDPA is quite repeatable. The results are typically 3 to 5 microns smaller than the existing calibrations for a given run condition. Reasons for these differences are also discussed.

  13. Study of tunnelling through water-bearing fracture zones. Baseline study on technical issues with NE-1 as reference

    Energy Technology Data Exchange (ETDEWEB)

    Yanting Chang; Swindell, Robert; Bogdanoff, Ingvar; Lindstroem, Beatrice; Termen, Jens [WSP Sweden, Stockholm (Sweden) ; Starsec, Peter [SGI, Linkoeping (Sweden)

    2005-04-01

    The Swedish Nuclear Fuel and Waste Management Co (SKB) is responsible for the management of Sweden's nuclear waste. SKB is investigating various designs for the construction of an underground deep repository for spent nuclear fuel at 500-600 m depths. For the construction of an access tunnel for such a deep repository, the possibility of encountering a water-bearing fracture zone cannot be discounted. Such a zone named NE-1 (deformation zone in accordance to SKB's terminology) was encountered during the construction of the Aespoe Hard Rock Laboratory (HRL) and difficulties with large water inflows were reported. With the aim to assess the feasibility of different technical solutions, SKB commissioned a baseline study into the passage of an access tunnel through a water-bearing fracture zone at three different depths (200 m, 400 m and 600 m). The objectives of this baseline study are to: Increase the knowledge of possible technical solutions for tunnelling through water-bearing fractures zones with the characteristics of the brittle deformation zone NE-1 at different depths, namely 200, 400 and 600 metres; Form a reference document to assist the engineering design and construction work for the passage through such a water-bearing fracture zone; To highlight the engineering parameters that should be obtained to facilitate design for the passage through water-bearing fracture zones.The study has been carried out in the following five stages: A. Compilation of the relevant data for deformation zone NE-1; B. Problem identification and proposal of technical solutions; C. Identification of hazards to be involved in the tunnel excavation; D. Recommendations and conclusions for further investigations; E. Documentation of the results in a final report. The analyses will be expressed in statistical/probabilistic terms where appropriate. In order to specify the precondition that will be valid for this study, a descriptive model of the water-bearing fracture zone is

  14. From the tunneling dimer to the onset of microsolvation: Infrared spectroscopy of allyl radical water aggregates in helium nanodroplets

    Science.gov (United States)

    Leicht, Daniel; Kaufmann, Matin; Pal, Nitish; Schwaab, Gerhard; Havenith, Martina

    2017-03-01

    The infrared spectrum of allyl:water clusters embedded in helium nanodroplets was recorded. Allyl radicals were produced by flash vacuum pyrolysis and trapped in helium droplets. Deuterated water was added to the doped droplets, and the infrared spectrum of the radical water aggregates was recorded in the frequency range 2570-2820 cm-1. Several absorption bands are observed and assigned to 1:1 and 1:2 allyl:D2O clusters, based on pressure dependent measurements and accompanying quantum chemical calculations. The analysis of the 1:1 cluster spectrum revealed a tunneling splitting as well as a combination band. For the 1:2 cluster, we observe a water dimer-like motif that is bound by one π-hydrogen bond to the allyl radical.

  15. On Technique to Construct Tunnel of Dongshan Water Supply Project%东山供水工程隧洞施工技术

    Institute of Scientific and Technical Information of China (English)

    王波

    2012-01-01

    通过东山供水工程隧洞工程实例,重点论述了工程的开挖、初期支护、二次混凝土衬砌施工技术,为长距离隧洞工程施工总结经验。%Taking the tunnel project of Dongshan Water Supply Project as an actual example , the paper emphatically elaborates tunnel excavation , preliminary support , placing second-stage concrete lining , puts forward summation of construction experiences for constructing tunnel with long length.

  16. 涌水隧道施工技术控制方法%Construction technology control method of gushing water tunnel

    Institute of Scientific and Technical Information of China (English)

    陈其亮

    2012-01-01

    Through the project example of Foling tunnel,this paper discussed the treatment methods of gushing water tunnel,put forward the management method combining "prevent,section,row,blocking",and used advanced auxiliary tunnel drained water gushing,advance grouting method for pre-support,provided technical reference for similar tunnel construction.%结合佛岭隧道工程实例,对涌水隧道的处理方法进行了探讨,提出"防、截、排、堵"相结合的治理方法,并采用超前辅助导坑引排涌水、超前注浆方法进行预支护,为同类隧道施工提供技术参考。

  17. Hydrogeology and groundwater quality at monitoring wells installed for the Tunnel and Reservoir Plan System and nearby water-supply wells, Cook County, Illinois, 1995–2013

    Science.gov (United States)

    Kay, Robert T.

    2016-04-04

    Groundwater-quality data collected from 1995 through 2013 from 106 monitoring wells open to the base of the Silurian aquifer surrounding the Tunnel and Reservoir Plan (TARP) System in Cook County, Illinois, were analyzed by the U.S. Geological Survey, in cooperation with the Metropolitan Water Reclamation District of Greater Chicago, to assess the efficacy of the monitoring network and the effects of water movement from the tunnel system to the surrounding aquifer. Groundwater from the Silurian aquifer typically drains to the tunnel system so that analyte concentrations in most of the samples from most of the monitoring wells primarily reflect the concentration of the analyte in the nearby Silurian aquifer. Water quality in the Silurian aquifer is spatially variable because of a variety of natural and non-TARP anthropogenic processes. Therefore, the trends in analyte values at a given well from 1995 through 2013 are primarily a reflection of the spatial variation in the value of the analyte in groundwater within that part of the Silurian aquifer draining to the tunnels. Intermittent drainage of combined sewer flow from the tunnel system to the Silurian aquifer when flow in the tunnel systemis greater than 80 million gallons per day may affect water quality in some nearby monitoring wells. Intermittent drainage of combined sewer flow from the tunnel system to the Silurian aquifer appears to affect the values of electrical conductivity, hardness, sulfate, chloride, dissolved organic carbon, ammonia, and fecal coliform in samples from many wells but typically during less than 5 percent of the sampling events. Drainage of combined sewer flow into the aquifer is most prevalent in the downstream parts of the tunnel systems because of the hydraulic pressures elevated above background values and long residence time of combined sewer flow in those areas. Elevated values of the analytes emplaced during intermittent migration of combined sewer flow into the Silurian aquifer

  18. Research on influence of discharge tunnel slope on aerated water flow

    Science.gov (United States)

    Chen, Hui; Chen, Baiquan

    2017-08-01

    The influence on hydraulic characteristics and the law of aeration concentration change was studied of slope in the different slope of the bottoms by the experiments, and some benefit conclusions was get. With the experimental data, the empirical formulas of hydraulic calculation of the diversion tunnel was revised which can provide a reference for the design of the project with the sudden expansion and drainage.

  19. INTERFERENCE OF SIDE STRUT WITH THE NATURAL CAVITATING FLOWS AROUND A SUBMERGED VEHICLE IN WATER TUNNEL EXPERIMENTS

    Institute of Scientific and Technical Information of China (English)

    CHEN Xin; YAO Yan; LU Chuan-jing; CHEN Ying; CAOJia-yi

    2011-01-01

    To apply the measurements of model experiment in water tunnel to the actual sailing condition,it is necessary to know accurately the strut effect and its rule.In the present work,the corresponding interferences of one-side strut and two-side strut on the natural cavitating flows around a submerged vehicle in water tunnel were investigated numerically,using the homogeneous equilibrium two-phase model coupled with a natural cavitation model.The numerical simulation results show that the strut types have distinct effects on the hydrodynamic properties.For the same given upstream velocity and downstream pressure,the existence of the strut leads to an increment of natural cavitation number,reduces the low-pressure region and depresses the pressure on the vehicle surface near the sides of strut.In the case of given cavitaiton number,the influences of the two-side strut on the drag and lift coefficients are both enhanced along with the increment of attack angle,however the influence of the one-side strut gradually gets stronger on the drag coefficient but weaker on the lift coefficient contrarily.In addition,based on the present numerical results,a correction method by introducing the sigmoidal logistic function is proposed to eliminate the interference from the foil-shaped strut.

  20. Tunneling Out of the Darkness: Rescuing Rare Samples and Data from the Geologic Survey of New York City Water Tunnel #3

    Science.gov (United States)

    Block, K. A.; Randel, C.; Ismail, A.; Palumbo, R. V.; Cai, Y.; Carter, M.; Lehnert, K.

    2016-12-01

    Most geologic samples of New York City (NYC) have been collected during city construction projects. Studies of these samples are essential for our understanding of the local geology as well as the tectonic processes that shaped the entire Appalachian region. Among these is a suite of rare high-grade granulite samples collected during the construction of the Brooklyn-Queens section of NYC Water Tunnel #3 have been resting dormant in the basement of the City College of New York (CCNY), studied by a small group of investigators with institutional knowledge, but largely undiscoverable and inaccessible to the broader scientific community. Data derived from these samples remain in disparate places, at best in analog format in publications or theses or, at worst, in spreadsheets stored on local machines or on old media, such as CDs and even floppy disks. As part of the Interdisciplinary Earth Data Alliance - CCNY joint internship program, 3 undergraduate students inventoried hundreds of samples and archived sample metadata in the System for Earth Sample Registration (SESAR), a sample metadata registry. Upon registration, each sample was assigned an International GeoSample Number (IGSN) ‒ a globally-unique and persistent identifier that allows unambiguous citation of samples and linking of disparate analytical data across the literature. The students also compiled geochemical analyses, thin-section images, and associated analytical metadata for publication in the EarthChem Library, where the dataset will be openly and persistently accessible and citable via a DOI (Digital Object Identifier). Not only did the internship result in the illumination of countless dark samples and data values, but it also provided the students with valuable lessons in responsible sample and data management, training that should serve them well in their future scientific endeavors.

  1. Caldecott 4th bore tunnel project: influence of ground water flows and inflows triggered by tectonic fault zones?

    Science.gov (United States)

    Neuhuber, G.; G. Neuhuber1, W. Klary1, A. Nitschke1, B. Thapa2, Chris Risden3, T. Crampton4, D. Zerga5

    2011-12-01

    nearly perpendicular, separating different geological units were expected along the 4th Bore alignment. This paper will describe encountered ground conditions adjacent to the fault contact where rock conditions are influenced to an extent of 5ft to 85ft from the contact. This paper will also compare the anticipated inflow of 55gpm within 100ft of the top heading excavation and fault zones inflow rates up to 110gpm to the actual measured maximum inflow into the tunnel of150gpm away from fault zones to a maximum inflow between 60gpm and 100gpm near fault zones. In presence of fault zones the water inflow is significant lower than expected and in absence of fault zones higher inflow rates as expected were measured. This paper will discuss the influence of fault zones on the water inflow - or are rock properties and lithology more significant?

  2. Treatment Technology for Water Gushing in Jinyu Tunnel%金鱼隧道涌水处治技术

    Institute of Scientific and Technical Information of China (English)

    李建民; 李晓梦; 吕琦

    2012-01-01

    The area of Jinyu tunnel is rich in water in the first-stage project of Mianmao highway and part of sections have water gushing. As for this conditions, through the the cause analysis, the calculations of water inflow and the hydrogeological survey, different treatment measures are developed. Through the comparison and selection,techniques that combining grouting and blocking water with drainage are adopted which are proved to be the most safe technique and succeed in solving the problem of water gushing ultimately.%绵茂公路一期工程金鱼隧道隧址区含水丰富,部分地段有涌水,针对此情况,通过时隧址区水文地质进行调绘及对涌水原因的分析和涌水量的计算,制订了不同的处治方案,并进行比选,采用了安全性最好的拦排相结合的施工技术,最终成功解决了该隧道的涌水问题。

  3. Water-tunnel and analytical investigation of the effect of strake design variables on strake vortex breakdown characteristics

    Science.gov (United States)

    Frink, N. T.; Lamar, J. E.

    1980-01-01

    A systematic water-tunnel study was made to determine the vortex breakdown characteristics of 43 strakes. The strakes were mounted on a 1/2-scale model of a Langley Research Center general research fighter fuselage model with a 44deg leading-edge-sweep trapezoidal wing. The analytically designed strake shapes provided examples of the effects of the primary design parameters (size, span, and slenderness) on vortex breakdown characteristics. These effects were analyzed in relation to the respective strake leading-edge suction distributions. Included were examples of the effects of detailed strake planform shaping. It was concluded that, consistent with the design criterion, those strakes with leading-edge suction distributions which increase more rapidly near, and have a higher value at, the spanwise tip of the strake produce a more stable vortex.

  4. Predictive analysis of stress regime and possible squeezing deformation for super-long water conveyance tunnels in Pakistan

    Institute of Scientific and Technical Information of China (English)

    Wang Chenghu; Bao Linhai

    2014-01-01

    The prediction of the stress field of deep-buried tunnels is a fundamental problem for scientists and engineers. In this study, the authors put forward a systematic solution for this problem. Databases from the World Stress Map and the Crustal Stress of China, and previous research findings can offer prediction of stress orientations in an engineering area. At the same time, the Andersonian theory can be used to analyze the possible stress orientation of a region. With limited in-situ stress measurements, the Hoek–Brown Criterion can be used to estimate the strength of rock mass in an area of interest by utilizing the geotechnical investigation data, and the modified Sheorey’s model can subsequently be employed to predict the areas’ stress profile, without stress data, by taking the existing in-situ stress measurements as input parameters. In this paper, a case study was used to demonstrate the application of this systematic solution. The planned Kohala hydropower plant is located on the western edge of Qinghai–Tibet Plateau. Three hydro-fracturing stress measurement campaigns indicated that the stress state of the area is SH>-Sh>SV or SH>SV>Sh. The measured orientation of SH is NEE (N70.3?–89?E), and the regional orientation of SH from WSM is NE, which implies that the stress orientation of shallow crust may be affected by landforms. The modified Sheorey model was utilized to predict the stress profile along the water sewage tunnel for the plant. Prediction results show that the maximum and minimum horizontal principal stres-ses of the points with the greatest burial depth were up to 56.70 and 40.14 MPa, respectively, and the stresses of areas with a burial depth of greater than 500 m were higher. Based on the predicted stress data, large deformations of the rock mass surrounding water conveyance tunnels were analyzed. Results showed that the large deformations will occur when the burial depth exceeds 300 m. When the burial depth is beyond 800 m, serious

  5. A Theoretical Investigaon on the Motion of a Straight Vortex Line in Water Tunnel%水筒中直线涡运动的理论探讨

    Institute of Scientific and Technical Information of China (English)

    郭永松

    1985-01-01

    本文讨论了正方形截面水筒中直线涡的运动.当涡线不位于水筒中心线上时,数值计算表明,涡线在水筒截面平面上将沿近似螺旋线的轨迹运动.若涡线接近水筒中心线,则轨迹接近圆.文章详细分析了位于水筒中心线直涡线的运动稳定性,其结论是除了零波数的扰动,在其他任何波数的扰动下,涡线总可保持在水筒中心线上.对于零波数扰动,则与不位于水筒中心线的涡线运动情况一样,将逐步偏离水筒中心.%In this paper the motion of a straight vortex line in a water tunnel having a square cross section is discussed. When the vortex line is not positioned at the centric Iine of water tunnel, it is found through numerical calculation that this vortex line will move along a trace of approximate spiral in the cross section plane. If the vortex line is close to the centric line of water tunnel the trace is nearly a circle. As for the vortex line located in the centric line of water tunnel,its stability of motion is analysed in detail and the conclusion is that it can be always kept at the centric line of water tunnel for any different wavenumber purturbation except zero wavenumber. In the case of the perturbation of zero wavenumber the situation is the same as a vortex line which is not located at the centric line of water tunnel and it will gradually depart from the centric line of water tunnel.

  6. 山岳隧道施工受温泉流水影响之探讨%Study on Influence of Mountain Tunnel Excavation under Hot Spring Water

    Institute of Scientific and Technical Information of China (English)

    胡文丰; 张义隆

    2014-01-01

    In recent years,excavations of mountain tunnel are involved in the development of some major construction in Taiwan.However,it is located between Eurasia plate and Philippine plate,and hot springs are easily founded. Temperature inside the tunnel is always much higher than that outside during tunnel excavation.This is the reason why scheduled tunnels are going to suffer the same problem.In this study,the data collection and the schedule information of the tunnel construction in practical cases are used to probe the factors of how hot spring water affects the schedule of construction.By means of experience of tunnel construction in practical cases and construction records and other information of the scene,valuable references and applications of high-temperature tunnel excavation are expected to be provided.%近年来,台湾开发的部分重大建设均牵涉山岳隧道的开挖,因台湾地处欧亚板块与菲律宾板块交界处,受其影响,常发现有温泉形成。隧道内如有温泉水流出,则相比一般隧道外的作业环境温度要高出很多,而大部分隧道会遇到温泉水的问题。本研究针对实际工程案例的现地探查数据及隧道开挖施工效率进行分析,探讨了温泉水对隧道施工的影响,以期为高温隧道开挖施工提供借鉴参考。

  7. In situ scanning tunneling microscopy study of Ca-modified rutile TiO2(110 in bulk water

    Directory of Open Access Journals (Sweden)

    Giulia Serrano

    2015-02-01

    Full Text Available Despite the rising technological interest in the use of calcium-modified TiO2 surfaces in biomedical implants, the Ca/TiO2 interface has not been studied in an aqueous environment. This investigation is the first report on the use of in situ scanning tunneling microscopy (STM to study calcium-modified rutile TiO2(110 surfaces immersed in high purity water. The TiO2 surface was prepared under ultrahigh vacuum (UHV with repeated sputtering/annealing cycles. Low energy electron diffraction (LEED analysis shows a pattern typical for the surface segregation of calcium, which is present as an impurity on the TiO2 bulk. In situ STM images of the surface in bulk water exhibit one-dimensional rows of segregated calcium regularly aligned with the [001] crystal direction. The in situ-characterized morphology and structure of this Ca-modified TiO2 surface are discussed and compared with UHV-STM results from the literature. Prolonged immersion (two days in the liquid leads to degradation of the overlayer, resulting in a disordered surface. X-ray photoelectron spectroscopy, performed after immersion in water, confirms the presence of calcium.

  8. Short tunnels.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1965-01-01

    Before dealing with the question of lighting short tunnels, it is necessary define what is meant by a tunnel and when it should be called 'short'. Confined to motorized road traffic the following is the most apt definition of a tunnel: every form of roofing-over a road section, irrespective of it le

  9. An Assessment of the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

    Science.gov (United States)

    Steen, Laura E.; Ide, Robert F.; Van Zante, Judith F.

    2015-01-01

    The NASA Glenn Icing Research tunnel has been using an Icing Blade technique to measure cloud liquid water content (LWC) since 1980. The IRT conducted tests with SEA Multi-Element sensors from 2009 to 2011 to assess their performance in measuring LWC. These tests revealed that the Multi-Element sensors showed some significant advantages over the Icing Blade, particularly at higher water contents, higher impingement rates, and large drop sizes. Results of these and other tests are presented here.

  10. 隧道涌水量预测计算方法探讨%Discuss on method for predicting amount of water gushing in tunnel

    Institute of Scientific and Technical Information of China (English)

    杨超

    2013-01-01

    Based on the basic principles of 2 calculation methods for predicting amount of water gushing in tunnel, the calculation approaches, formulae and suitable conditions are discussed. The predicting water gushing with appropriate calculation method is helpful to make both the early warming and the construction countermeasure concerned. Taking Gao-ling tunnel in Hang-Chang railway as a case, the amount of water gushing in tunnel is predicted with water-balance method, then evaluates its water gushing amount and Puts forward corresponding Suggestions of engineering, and the provides a better technical support for the smooth implementation of the project.%  从2种隧道涌水量计算方法的基本原理出发,讨论了其计算步骤、公式及适用条件。选择合适的计算方法预测涌水量,有助于预警和制定施工对策。以杭长铁路高岭隧道工程为例,采用水均衡法对隧道进行涌水量预测,然后对其涌水量进行评价和提出相应的工程建议,为工程的顺利实施提供了技术支持。

  11. Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Ignacio Boron

    2015-07-01

    Full Text Available Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O2 and •ŸNO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels interrupted by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify Ÿ•NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO. In order to investigate the differences between these proteins, we performed experimental kinetic measurements, Ÿ•NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations affect both the tunnels accessibility as well as the affinity of distal site water molecules, thus modifying the ligand access to the iron. We found that a single mutation allows Mt-trHbN to acquire ligand migration rates comparable to those observed for Mt-trHbO, confirming that ligand migration is regulated by the internal tunnel architecture as well as by water molecules stabilized in the active site.

  12. Construction of Taigu Tunnel in Water- bearing Formation%太峪隧道含水地层施工研究

    Institute of Scientific and Technical Information of China (English)

    高延平

    2011-01-01

    研究目的:太峪隧道含水地层整体性较差,施工难度大,施工存在较大安全隐患.正确认识该套地层以及研究适宜的支护衬砌参数,保证隧道工程通过该套地层隧道施工的安全合理.研究结论:(1)太峪隧道含水地层成因复杂,地层具有一定的压密性,但作为下更新统地层却胶结程度差,丰富的地下水对隧道施工影响很大.(2)该隧道地质条件复杂且赋存地下水,施工中必须严格注意围岩及涌水量的变化,随时调整施工方案,以保证施工安全.(3)对未来其他项目可能会遇到类似地层的施工应审慎对待,切不可轻视,做到有备无患.%Research purposes: The integrity of the water - bearing formation in the Taigu Tunnel was poor and it was difficult to construct a tunnel in this area with great potential safety hazard. Correctly recognizing this stratum and studying the appropriate parameters for lining support were crucial to safe construction of the tunnel in water - bearing formation.Research conclusions: (1) The origin of the water - bearing formation in the Taigu Tunnel was complex. The water -bearing formation had a certain compaction property, but it was poor in cementation as the lower Pleistocene stratum, with big influence of rich underground on the construction of the tunnel. (2 ) As the geological condition of the tunnel was complicated with much underground water, the construction plan would be adjusted according to the situation of the surrounding rocks and the volume of water bursting so as to ensure the construction safety. (3 ) The more attention should be paid to the construction in the similar formations in future for the construction safety.

  13. Thermal usage of drainage water at the northern entrance to the Gotthard base railway tunnel - Feasibility study, phase II; Waermenutzung Tunnelwasser Basistunnel Gotthard, Nordportal

    Energy Technology Data Exchange (ETDEWEB)

    Dups, Ch. [Gruneko AG, Basel (Switzerland)

    2004-07-01

    This final report for 2004 presents a review of the results of work done on behalf of the Swiss Federal Office of Energy (SFOE) on research into the possible uses of the rock water collected behind the tunnel linings of the new Gotthard base tunnel under the Swiss Alps. This report regards only the northern entrance. Estimates of the quantity of drainage water and its temperature are presented, as are possible uses for the warm water as a basis for district heating, individual heat-pumps as well as for greenhouses, fish breeding and mushroom farming. Figures are quoted on effective heating-energy costs and reductions in fossil-fuel use to be attained. The high sensitivity of the energy price to changes in electricity prices and to the degree to which buildings are connected to a district heating system is discussed. Possible use of the tunnel water in other municipalities in the area are also listed. Figures on heating-power and heating-energy supply are quoted for several of the various possible projects.

  14. Thermal usage of drainage water at the southern entrance to the Gotthard base railway tunnel - Feasibility study, phase II; Waermenutzung Tunnelwasser Basistunnel Gotthard, Suedportal. Machbarkeitsstudie Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Dups, Ch. [Gruneko AG, Basel (Switzerland)

    2004-07-01

    This final report presents a review of the results of work done on behalf of the Swiss Federal Office of Energy (SFOE) on research into the possible uses of the rock water collected behind the tunnel linings of the new Gotthard base tunnel under the Swiss Alps. This report regards only the southern entrance. Estimates of the quantity of drainage water and its temperature are presented, as are possible uses for the warm water as a basis for a tropical greenhouse, fish breeding, a wellness-spa, district heating, and individual heat-pumps as well as for heating the Alp Transit visitor centre. Figures are quoted on effective heating-energy costs and reductions to be obtained in fossil fuel use. The high sensitivity of the energy price with respect to electricity prices and the degree to which buildings are connected to a district heating system is discussed. Possible use of the tunnel water in other municipalities in the area are also listed. Figures on heating-power and heating-energy supply are quoted for several of the various possible projects.

  15. Negative catalytic effect of water on the reactivity of hydrogen abstraction from the C-H bond of dimethyl ether by deuterium atoms through tunneling at low temperatures

    Science.gov (United States)

    Oba, Yasuhiro; Watanabe, Naoki; Kouchi, Akira

    2016-10-01

    We report an experimental study on the catalytic effect of solid water on the reactivity of hydrogen abstraction (H-abstraction) from dimethyl ether (DME) in the low-temperature solid DME-H2O complex. When DME reacted with deuterium atoms on a surface at 15-25 K, it was efficiently deuterated via successive tunneling H-abstraction and deuterium (D)-addition reactions. The 'effective' rate constant for DME-H2O + D was found to be about 20 times smaller than that of pure DME + D. This provides the first evidence that the presence of solid water has a negative catalytic effect on tunneling H-abstraction reactions.

  16. 谈隧道突水及突泥灾害研究现状%On research status of tunnel water inrush and mud burst disasters

    Institute of Scientific and Technical Information of China (English)

    金兵; 陈四来

    2012-01-01

    From the perniciousness of tunnel water inrush,mud burst,this paper made analysis on the causes of tunnel water inrush,mud burst disasters,detection and prediction technology,the current research situation of treatment technology,had reference and application value to clear the current study.%从隧道突水、突泥的危害性入手,对隧道突水、突泥灾害成因、探测预报技术、处治技术的研究现状进行了分析,对明确当前的研究任务具有一定的参考和应用价值。

  17. Stresses and Displacements in Steel-Lined Pressure Tunnels and Shafts in Anisotropic Rock Under Quasi-Static Internal Water Pressure

    Science.gov (United States)

    Pachoud, Alexandre J.; Schleiss, Anton J.

    2016-04-01

    Steel-lined pressure tunnels and shafts are constructed to convey water from reservoirs to hydroelectric power plants. They are multilayer structures made of a steel liner, a cracked backfill concrete layer, a cracked or loosened near-field rock zone and a sound far-field rock zone. Designers often assume isotropic behavior of the far-field rock, considering the most unfavorable rock mass elastic modulus measured in situ, and a quasi-static internal water pressure. Such a conventional model is thus axisymmetrical and has an analytical solution for stresses and displacements. However, rock masses often have an anisotropic behavior and such isotropic assumption is usually conservative in terms of quasi-static maximum stresses in the steel liner. In this work, the stresses and displacements in steel-lined pressure tunnels and shafts in anisotropic rock mass are studied by means of the finite element method. A quasi-static internal water pressure is considered. The materials are considered linear elastic, and tied contact is assumed between the layers. The constitutive models used for the rock mass and the cracked layers are presented and the practical ranges of variation of the parameters are discussed. An extensive systematic parametric study is performed and stresses and displacements in the steel liner and in the far-field rock mass are presented. Finally, correction factors are derived to be included in the axisymmetrical solution which allow a rapid estimate of the maximum stresses in the steel liners of pressure tunnels and shafts in anisotropic rock.

  18. Discussions on Ground Water Control Technologies for Tunneling in Ground Containing Rich High-pressure Water%高水压富水隧道地下水控制技术探讨

    Institute of Scientific and Technical Information of China (English)

    李治国

    2015-01-01

    During tunneling in ground containing rich high-pressure water,water inflow,mud bursting and collapse may occur due to the action the ground water,which may jeopardize the tunneling safety,the surrounding environment and even the tunnel operation.In the paper,the following two aspects are discussed on the basis of theoretical formulas, engineering cases and standards and specifications:1 )The water inflow rate and water pressure during tunneling are discussed on the basis of analysis on the ground water seepage flow rules and in the aspects of ground reinforcement and water stopping,pressure reducing under limited drainage and water pressure resistant lining;2)The classification of the drainage rate in tunneling and the control of the content of mud and sand in water and particle size are discussed and some control parameters and standards are proposed.Finally,the control of the rich high-pressure water in the construction of Zhongtianshan tunnel is presented.The paper can provide reference for similar works in the future.%高水压富水隧道施工中地下水的作用容易引发涌水突泥和坍塌,造成施工安全事故和破坏周围环境,甚至给运营带来安全隐患。文章通过理论公式、工程案例及规范规定等方面的分析,主要探讨了2方面的内容:1)通过分析地下水的渗流规律,从地层加固和止水、限排降压、抗水压衬砌等方面介绍了隧道涌水量和水压力;2)隧道排水量分级、水中泥砂含量及粒径控制问题,提出了一些控制参数和标准。并以中天山隧道为例,介绍了高水压富水区的地下水控制,促进高水压富水隧道的设计和施工水平的进一步提高,并供类似工程参考。

  19. 坑道水库储水防霉消毒对比研究%Comparative Study on Mildew Resistance and Disinfection of Tunnel Reservoir Water Storage

    Institute of Scientific and Technical Information of China (English)

    张永良; 侯小平; 苏青平; 周聚中

    2011-01-01

    Objective On the basis of the fungi pollution of the tunnel reservoir water storage, the effects of mildew resistance and disinfection on the water storage between sodium dichloroisocyanurate and chlorine dioxide disinfector were compared to provide a basis for water storage health security in wartime or under some special conditions. Methods Sodium dichloroisocyanurate and chlorine dioxide as mildew resistance disinfector for tunnel reservoir water storage were chosen to conduct laboratory tests, on - site simulation experirnents and on - site reservoir water storage mildew resistance and disinfection. Results Disinfecting water storage with sodium dichloroisocyanurate containing a concentration of available chlorine 20 mg/L based on the water storage capacity, the remained chlorine was 10.9 mg/L in the 24th month after disinfection.Disinfecting water storage with 5 mg/L chlorine dioxide, the concentration of chlorine dioxide was 0.01 mg/L in the third month after disinfection. Conclusion Sodium dichloroisocyanurate which has a good stability in the tunnel environment is suitable for long- time mildew resistance and disinfection of tunnel reservoir water storage. Disinfecting water storage with chlorine dioxide which has an ideal disinfectant effect in tunnel environment in 3 months is suitable for rapid and short - term disinfection of tunnel reservoir water storage.%目的 根据坑道水库储水真菌污染状况,对比观察二氯异氰尿酸钠和二氧化氯消毒剂对储水的防霉消毒效果,为战时或特殊情况下储水卫生保障提供依据.方法 选择二氯异氰尿酸钠和二氧化氯作为坑道水库储水防霉消毒剂,进行实验室试验、现场模拟试验以及现场水库储水防霉消毒.结果 根据储水量按有效氯20 mg/L二氯异氰尿酸钠消毒储水,消毒后24个月余氯量为10.9 mg/L.按5 mg/L二氧化氯消毒储水,消毒后3个月二氧化氯浓度为0.01mg/L.结论 二氯异氰尿酸钠在坑道环境中

  20. Tunneling effects in resonant acoustic scattering of an air bubble in unbounded water

    Directory of Open Access Journals (Sweden)

    ANDRÉ G. SIMÃO

    2016-06-01

    Full Text Available Abstract The problem of acoustic scattering of a gaseous spherical bubble immersed within unbounded liquid surrounding is considered in this work. The theory of partial wave expansion related to this problem is revisited. A physical model based on the analogy between acoustic scattering and potential scattering in quantum mechanics is proposed to describe and interpret the acoustical natural oscillation modes of the bubble, namely, the resonances. In this context, a physical model is devised in order to describe the air water interface and the implications of the high density contrast on the various regimes of the scattering resonances. The main results are presented in terms of resonance lifetime periods and quality factors. The explicit numerical calculations are undertaken through an asymptotic analysis considering typical bubble dimensions and underwater sound wavelengths. It is shown that the resonance periods are scaled according to the Minnaert’s period, which is the short lived resonance mode, called breathing mode of the bubble. As expected, resonances with longer lifetimes lead to impressive cavity quality Q-factor ranging from 1010 to 105. The present theoretical findings lead to a better understanding of the energy storage mechanism in a bubbly medium.

  1. Analysis on Source and Path of Gushing Water in Karst Tunnel%岩溶隧道突涌水来源及路径分析

    Institute of Scientific and Technical Information of China (English)

    刘强; 刘运来; 徐志华; 荣耀; 孙洋

    2016-01-01

    A geological analysis and a field investigation of the Nanshibi T unnel were conducted. T he source and the flow path of the sudden gushing water in the tunnel were analyzed with high density resistivity method,tracer experiment and geological radar method. T he results show that the gushing water is from the ground surface rainfall collection. It also may happen when the reservoir water level reaches to a degree. T he karst development in the vicinity of the tunnel provides water flow path,leading to the sudden gushing water.%通过对南石壁隧道地质条件的分析和地表现场踏勘,结合高密度电法、化学示踪法及地质雷达探测法,对隧道突涌水的来源和通道进行分析。结果发现:隧道突涌水主要由地表降水汇集而成,当附近水库的水位超过一定范围时也会发生突涌水;隧道突涌水严重地段附近岩溶发育,为隧道突涌水提供了渗漏路径。

  2. 输水通道中沼蛤入侵及水力学防治%Golden mussel invasion in water transfer tunnels and hydraulic prevention

    Institute of Scientific and Technical Information of China (English)

    徐梦珍; 王兆印; 王旭昭; 刘玮

    2013-01-01

      滤食性底栖动物沼蛤极易入侵水利工程的输水通道,在输水结构上高密度附着,造成生物污损,堵塞管道,降低输水效率,污染水质,腐蚀结构,威胁工程运行,也给跨流域调水带来潜在危险。本文对输水工程水源长期密集采样观测,研究沼蛤幼虫发育阶段及运动特性;开展水力试验,研究幼虫的沉降、在脉动流场中的死亡特性,提出防治幼虫入侵的方法。研究结果表明:沼蛤幼虫在其水中浮游生活的阶段,依赖水流流动入侵输水通道,通过分泌足丝附着在结构壁面。沼蛤幼虫、稚贝具有沉降特性,尺寸合适的沉降池能够使大量幼虫、稚贝沉底。幼虫会被高频湍流灭杀,当湍流中小涡尺度与幼虫体长相当时,对幼虫的灭杀效果显著,灭杀率与湍流平均流速及湍流作用时间正相关。防止沼蛤入侵输水通道的关键是减少水流中沼蛤幼虫的数量,可采用沉降及高频湍流灭杀沼蛤幼虫的综合方法实现防治目标。%The golden mussel (Limnoperna fortunei) is a filter-collector species of macroinvertebrate originat-ing from southern China. It easily invades into water transfer tunnels and attaches on tunnel walls and struc-tures with extremely high density, resulting serious biofouling, clogging pipes, decreasing water transfer effi-ciency, and causing water pollution and structure corrosion. It is an urgent need to seek effective measures for its prevention. Long term samplings and observations were performed to find planktonic golden mussel ve-ligers in source water of a water transfer project. The characters of golden mussel veligers in settlement and death in turbulence were studied through experiments. Measures of preventing golden mussel veligers in-vasion were proposed based on the veligers’characters. The results of long term observations indicate that golden mussel experiences planktonic veliger stages in

  3. Mechanism analysis and treatment technology of gushing water in Guanjiao tunnel%关角隧道突涌水机理分析及处治技术

    Institute of Scientific and Technical Information of China (English)

    钱富林

    2014-01-01

    为保证关角隧道顺利穿越岩溶富水区,通过现场调查、连通试验及对隧道突涌水水文地质概念模型的分析,研究关角隧道突涌水发生的机理。研究结果表明,关角隧道突涌水属揭穿型,受蓄水构造和降雨的影响明显。对隧道掌子面、洞身突涌水模式进行了理论分析,对不同的突涌水模式制订了针对性的超前地质预报、注浆或地表导流方案。论述了突涌水预防和治理方案的应用条件、施工工艺和技术要点。%T he paper aims to study the reasons of gushing water in Guanjiao tunnel,with the purpose of leading the tunnel out from the karst water-rich area. W ith that in mind,it takes the approaches of in-situ investigation, connected tests and model simulation of the surrounding geo-hydraulic environment. T he research points out that the gushing w ater is subjected to the storage structure and rainfall. In this light,the paper carried out theoretical analysis on the w orking face and the body of such tunnel,and further proposes geological alarm ,grouting,and surface discharge as solutions. Beyond that,conditions and techniques for such precautions scheme and treatment measures are outlined as w ell.

  4. The Treatment Measures of Water Bursting and Mud Gushing of Panling Highway Tunnel%盘岭公路隧道涌水突泥治理措施

    Institute of Scientific and Technical Information of China (English)

    林承华; 尹术军

    2014-01-01

    鉴于公路隧道涌水突泥地质灾害具有危害大、治理难的特点,以贵州省三穗至黎平高速公路盘岭隧道为背景,阐述了隧道右洞第一次、第二次涌水突泥过程和治理措施及效果,2次分别采用超前管棚注浆、全断面帷幕注浆加固围岩,治理效果前者欠佳、后者显著。%The geological disaster of water bursting and mud gushing in highway tunnel is greatly harmful and difficult to control.Taking the section from Sanhui to Liping of the Panling highway tun-nel in Guizhou province as the background,the results and treatments of the first and the second time of water bursting and mud gushing process in the right hole are investigated.It is shows that the re-sult of full-face curtain grouting treatment is better than that of the lead pipe-roof grouting treatment.

  5. Study on curtain grouting sand-consolidating and water-shutoff technique used in overall Xiushan tunnel section%秀山隧道全断面帷幕注浆固砂止水技术研究

    Institute of Scientific and Technical Information of China (English)

    陈先智; 韩银利

    2012-01-01

    In light of characteristics of Xiushan tunnel with complicated hydrological conditions and high surrounding water sources demands, curtain grouting water-shutoff technique is applied which is good for protecting ecological environment of the tunnel top and reducing future trou- ble. As a result, the construction difficulties including high-pressure water gushing in the tunnel and sudden sand are successfully solved.%针对秀山隧道水文地质条件较复杂,周围水资源环境要求高的特点,通过采用有利于保护洞顶生态环境、减少后患的帷幕注浆堵水技术,成功地解决了洞内高压涌水、突砂等施工难题。

  6. The governance program of water gushing in long-deep metro tunnel%长大深埋地铁隧道涌水治理方案

    Institute of Scientific and Technical Information of China (English)

    张建波

    2014-01-01

    For the water gushing of metro underground interval, the paper discusses in detail the targeted governance program of different water gushing position on the basis of the Zhongliangshan tunnel of Chongqing metro line 1. The paper is aimed at supplying reference to the similar projects.%针对轨道交通地下区间涌水的情况,以重庆轨道交通一号线中梁山隧道为例,详细论述了地铁隧道不同涌水部位分别制定的针对性治理方案,旨在对类似工程提供一些参考。

  7. Stability Analysis of Lining Structure of Water Diversion Tunnel of Hydropower in Earthquake Area%强震区水电站引水隧洞衬砌结构动力稳定性分析

    Institute of Scientific and Technical Information of China (English)

    刘立新

    2016-01-01

    为了获得100年超越概率1%的地震作用下水电站引水隧洞衬砌结构的动力稳定性,采用动力时程法对某大型水电站的引水隧洞进行了三维动力分析,得到了引水隧洞各个关键位置在地震作用下的应力、位移、加速度的响应及塑性区分布特征。计算结果表明:引水隧洞的衬砌结构均按照激励地震动做相似的受迫振动,地震动峰值越大,衬砌结构的动位移和拉、压应力就越大。在引水隧洞进口处的上平段的拉、压应力最大,最大拉应力为1.3 MPa。隧洞衬砌拉应力在水平向上并不对称,每条隧洞靠近另一条隧洞的一侧,应力值较大,而远离另一条隧洞的一侧,应力值较小。引水洞塑性区离隧洞进、出口距离愈远,塑性区范围愈小,8条引水洞之间围岩的塑性区均未发生贯通。地震作用结束后,8条引水隧洞的围岩只有在出口位置发生塑性区贯通。引水隧洞在100年超越概率1%的地震工况下,局部会发生破坏,但整体上是安全稳定的。%To obtain dynamic stability of lining structure of water diversion tunnel under the 100 years beyond 1% proba-bility earthquake condition,the three-dimensional dynamic analysis for water diversion tunnel of large hydropower station is conducted by the dynamic time history method.The distribution of plastic zone and response characteristics of the stress and the displacement and acceleration of each key position of water diversion tunnel under earthquake is obtained.It is shown that the lining structure of the diversion tunnel makes similar forced vibration in accordance with the excitation earthquake. The peak value of earthquake is larger,the dynamic displacement,tensile stress and compressive stress of lining structure is greater.The compressive stress and tensile stress of the diversion tunnel inlet on the horizontal section is the biggest.The maximum tensile stress is 1.3 MPa

  8. Geologic Cause Analysis of Sudden Gushing Water of a Mountain Tunnel in the Construction Stage%某山岭隧道施工阶段突发涌水地质成因分析

    Institute of Scientific and Technical Information of China (English)

    刘晓锋; 苏丽薇

    2012-01-01

    To counter the phenomenon of sudden gushing water in the mountain tunnel construction stage, after comprehensive analysis of engineering geologic and hydrogeological condition of the tunnel area, relations between quantity of gushed water in the tunnel and the water level of the surface wateL geologic condition of the tunnel face and the pond in the tunnel area, we conclude that the connectivity of the fault fracture zones and its influence zones brings the closely hydraulic connection between the pond and the gushing water tunnel(RK5+917-RK5+903), which is the main geologic cause of the sudden gushing water.%文中针对某山岭隧道施工过程中掌子面出现地下水突发大量涌出的不良地质现象,从隧址区工程地质及水文地质条件、洞内涌水量与地表水体水位的联系、洞内掌子面地质条件、隧址地表山塘地质条件等角度进行综合分析,得出断层破碎带及其影响带之间的连通使得山塘与隧道涌水段(RK5+917-RK5+903)具有密切的水力联系,是突发涌水的主要地质成因。

  9. 化马隧道涌水处理浅析%Analysis of the Treatment of Water-gushing in Huama Tunnel

    Institute of Scientific and Technical Information of China (English)

    武世燕

    2012-01-01

    化马隧道涌水为高压宽张岩溶裂隙水,具水量大,压力高,涌水连续、贯通性好、补给水头稳定等特点。通过详细地质勘探、水文地质条件分析及准确地质超前预报,掌握了涌水的特点和性质,提出了采用迂回导坑绕避结合泄水洞排水的处理方案,顺利通过了隧道涌水段。%The water-gushing in Huama Tunnel is what called high-pressure fracture-karst water which is characterized by large quantity, high pressure, continuous supply, smooth flow, and stable source. By detailed geological survey, hydro-geological condition analysis, and precise geological prediction, the feather and quality of the water-gushing is known and treatment measures with water detouring and draw-off culvert are used to move through the water gushing section.

  10. 谈城市隧道给排水及消防系统设计方案%Tunnels of a city water supply and drainage and fire system design

    Institute of Scientific and Technical Information of China (English)

    朱志华

    2012-01-01

    In this paper, the urban tunnel drainage systems, fire water supply system and the automatic alarm system how to design is analyzed and discussed, including proposed horizontal cross-sectional entrance of the tunnel is located inside the vertical drain ditches and tunnels, the tunnel fire hydrant water supply system inside the ring with the aqueous film-forming foam fire-fighting equipment design, so as to ensure the smooth operation of the city tunnel eomstruction.%主要对城市隧道排水系统、消防给水系统及自动报警系统如何合理设计进行了分析和探讨,提出了包括隧道口设横向截水沟与隧道内设纵向排水沟、隧道内设环状消火栓供水系统与水成膜泡沫灭火装置设计方案,以期保证城市隧道建设顺利进行。

  11. Analysis of Water Inrush Danger of Subsea Tunnel Based on Water Inrush Coefficient of Water-resisting Key Strata%基于隔水关键层突水系数法的海底隧道施工突水危险性分析

    Institute of Scientific and Technical Information of China (English)

    李兵; 张顶立

    2011-01-01

    Water inrush is the biggest safety risk during subsea tunnel construction stage, which often occurs in unfavorable geological bodies indicated by research. In order to understand and control the construction water inrush risk of unfavorable geological bodies in subsea tunnel, the type, factor and mode of water inrush in subsea tunnel are analyzed, the mechanism of construction water inrush of unfavorable geological bodies in subsea tunnel is analyzed, and failure of rock around tunnel induced by deformation is considered as the most reason, so it' s very important to study the rock covers of no damaged, then the water inrush coefficient of water-resisting key strata is introduced and used as the criteria of water inrush judgment in subsea tunnel. In the case of F1 weathered slot in the left line of Xiamen Subsea Tunnel, the influence factors of water inrush coefficient are discussed, and some useful conclusions are given. At last, water inrush coefficient is applied in the prediction of water inrush in F4 weathered slot, and be proved feasible and applicable.%突水是海底隧道施工阶段最大的安全风险,而且突水事故多发生在不良地质段.为了更好地控制海底隧道不良地质体施工突水风险,本文对海底隧道的突水模式及其影响因素进行了分析,指出海底隧道突水事故多与隧道开挖引起的围岩变形破坏有关,而未破坏岩层的研究对于突水的控制至关重要.因而,重点对海底隧道不良地质体顶板突水机理进行分析,引入隔水关键层的概念及判别条件,将隔水层关键层突水系数作为海底隧道顶板突水判断标准,以厦门海底隧道左线F1风化槽为例,对隔水关键层突水系数的影响因素进行分析,并将突水系数法应用于F4风化槽突水预测,证实了突水系数法的可行性和适用性.

  12. Tunnel Construction Water Inflow Predicted by Precipitation Infiltration Method%降水入渗法隧道施工涌水量预测

    Institute of Scientific and Technical Information of China (English)

    黄钟焕; 王玲

    2011-01-01

    Water inflow is generally obtained form well pumping test. But in geological survey and route selection , the precipitation infiltration method is used in the prediction the wate inflow of the construction of the tunnel because of the site condition and the cost constraints.%涌水量一般通过抽水试验取得,但在区域性地质调查或选线中,由于场地条件及费用限制,只能通过野外地质调查,用降水入渗法预测隧道涌水量,可为选线或初步预测隧道施工涌水量.

  13. Carpal Tunnel Syndrome

    Science.gov (United States)

    ... arm. Just a passing cramp? It could be carpal tunnel syndrome. The carpal tunnel is a narrow passageway of ligament and ... difficult. Often, the cause is having a smaller carpal tunnel than other people do. Other causes include ...

  14. ANALYSIS ON TUNNEL WATER GUSHING OF SHIZUI COPPER MINE IN PANSHI CITY%磐石石咀铜矿坑道涌水分析

    Institute of Scientific and Technical Information of China (English)

    王岩; 田广明

    2015-01-01

    磐石石咀铜矿位于吉林省中南部磐石-明城背斜的东翼,区内经历了多期多阶段构造运动.矿体赋存于石咀子组大理岩、硅质条带大理岩中,岩石溶隙、溶洞较发育,地质条件复杂.从矿区水文地质特征、地下水补迳排关系、矿坑充水因素等要素入手,综合分析坑道涌水特点、涌水规律,并预测其涌水量,指导矿山水文地质工作.%The Shizui copper mine of Panshi is located at the east limb of Mingcheng anticline in Jilin province. It has undergone multi-stage tectonic movements. The ore bodies occur in marble and Siliceous bands marble of Shizuizi Formation. The solution fissure and karst cave developed well in rock, and the geological condition is complex. According to the hydrogeological feature, the groundwater recharge, flow and discharge relationship as well as mining water filling factors, we analysed the feature and the law of tunnel water gushing synthetically and predicted the water yield in order to guide the hydrogeological work.

  15. Model Study of Risk Assessment about Water Bursting and Mud Gushing in Tunnel%隧道涌水突泥风险评价模型研究

    Institute of Scientific and Technical Information of China (English)

    翁其能; 吴秉其; 向帅; 李彪; 曾龙全

    2012-01-01

    结合层次分析法和模糊综合评价法,对涌水突泥这一灾害建立了风险评价模型,并对其进行量化处理,通过模糊—综合评价方法得到隧道涌水突泥风险评价模型.最后,将该风险模型应用于铁峰山隧道实例中,可以较明确的表达特定条件下隧道的涌水突泥风险级别,具有较高的可靠性和合理性.%This article combines the way of hierarchy analysis with fuzzy comprehensive evaluation to establish the risk assessment model of water bursting and mud gushing. By the way of quantization and fuzzy comprehensive evaluation, the model of risk assessment in water bursting and mud gushing will be put out. Then this model will be applied in the tunnel of Tie Fengshan to have a clear definition about risk level in water bursting and mud gushing under specified conditions, which is reasonable and reliable.

  16. Calculation of Reduction Coefficient of Water Pressure on Underwater Tunnel Lining%水底隧道衬砌水压力折减系数估算

    Institute of Scientific and Technical Information of China (English)

    郑波; 王建宇; 吴剑

    2012-01-01

    水底隧道衬砌水压力是衬砌结构设计的关键参数之一,根据对衬砌水压力作用机制的探讨,"全堵型"隧道衬砌承担全部静水压力,而对于"排水型"隧道,衬砌只承受部分水压力,作用在衬砌上的水压力应该进行折减。根据渗流理论,推导了轴对称条件下衬砌水压力折减系数的理论公式及利用隧道衬砌前与衬砌后涌水量的反分析简化公式,并通过数值方法验证了其可靠性。计算结果表明:1)隧道涌水量随着衬砌渗透系数的减小而减少,当kl/ks=0.001时,涌水量几乎为0,而水压力折减系数近似等于1;2)对于不同的kl/ks值,水压力折减系数与涌水量存在一个公共点,这个交点范围为kl/ks=(0.02~0.03),对应的水压力折减系数约为0.5;3)对围岩进行注浆可以有效减少涌水量,但仍会有较大的水压力作用在注浆圈上,对注浆圈的长期耐久性提出了较高的要求;4)利用隧道衬砌前后涌水量推导的衬砌水压力折减系数反分析公式,其计算结果可靠、有效,可以在以后隧道结构设计中应用。%The water pressure on the tunnel lining is one of the key parameters of tunnel structure design. The water prooftype lining bears hydrostatic pressure. However, the drainagetype lining usually partially responds to the hydro static pressure. The hydrostatic pressure exerted on the lining should be reduced. The water pressure reduction coeffi cient of the lining under the conditions of axial symmetry is deduced, and its reliability is verified by means of numerical method, on basis of waterseepage theory. The calculation results show : 1 ) The water inflow decreases as the lining per meability reduces. When the value of kl/k,is 0. 001, there is almost no water inflow and the water pressure reduction coefficient is nearly equal to 1. 2) There is a public intersection between the water inflow and the water pressure reduc tion coefficient for

  17. Detecting and monitoring of water inrush in tunnels and coal mines using direct current resistivity method: A review

    OpenAIRE

    Shucai Li; Bin Liu; Lichao Nie; Zhengyu Liu; Mingzhen Tian; Shirui Wang; Maoxin Su; Qian Guo

    2015-01-01

    Detecting, real-time monitoring and early warning of underground water-bearing structures are critically important issues in prevention and mitigation of water inrush hazards in underground engineering. Direct current (DC) resistivity method is a widely used method for routine detection, advanced detection and real-time monitoring of water-bearing structures, due to its high sensitivity to groundwater. In this study, the DC resistivity method applied to underground engineering is reviewed and...

  18. Effect of non-uniform excitation on seismic response of long-distance water-conveyance tunnel%非一致激励下长距离输水隧道地震响应分析

    Institute of Scientific and Technical Information of China (English)

    禹海涛; 袁勇; 顾玉亮; 杨志豪

    2013-01-01

      Long tunnels suffered great damages in recent earthquakes frequently. With the increasing of large amount of water conveying engineering under construction, the seismic performance of long-distance water-conveying tunnels is significant. Based on the deficiency of traditional method for large-scale seismic computation,a large-scale analysis method is proposed to solve the non-uniform seismic response problems of the complex soil-long tunnel-water system. As an application,the presented method is used in an exist⁃ing long-distance water tunnel,which is one of the key projects in Shanghai. Both the nonlinear hysteretic constitutive model of soil and nonlinear contact behaviors between soil and tunnel are considered in the es⁃tablished numerical model. Furthermore,the added mass method is introduced to simplify the effect of dy⁃namic water pressure on the tunnel liner when subjected to seismic loadings. Two seismic input modes,the uniform and non-uniform excitations,are involved in the seismic analyses of the long water tunnel system. Compared with the uniform seismic input, the results show that the non-uniform excitation can remarkably increase both stress and deformation responses of the long tunnel, which makes adverse influence on the seismic performance of the tunnel. The research conclusions are beneficial to proving theoretical criterions for seismic design and analysis of long water-conveying tunnels.%  近年长隧道结构震害频发,随着调水工程大规模建设,长距离输水隧道抗震性能的重要性愈加突出。在隧道传统抗震分析方法的基础上,针对非一致地震动作用下地基土-长距离输水隧道体系的地震响应问题,建立了非一致激励下长距离输水隧道的大规模地震响应分析方法,并以上海市某重点工程中的长距离输水隧道为工程应用,计算模型中不仅考虑了土体的动力滞回非线性、土体与隧道之间的接触非线性等因素

  19. Snow and ice blocking of tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Lia, Leif

    1998-12-31

    Hydroelectric power development in cold regions causes much concern about operational reliability and dam safety. This thesis studies the temperature distribution in tunnels by means of air temperature measurements in six tunnel spillways and five diversion tunnels. The measurements lasted for two consecutive winters. The air through flow tunnel is used as it causes cooling of both rock and water. In open spillway tunnels, frost reaches the entire tunnel. In spillway tunnels with walls, the frost zones reach about 100 m from the downstream end. In mildly-inclined diversion tunnels, a frost free zone is located in the middle of the tunnel and snow and ice problems were only observed in the inlet and outlet. Severe aufeis is accumulation is observed in the frost zones. The heat transfer from rock to air, water and ice is calculated and used in a prediction model for the calculation of aufeis build-up together with local field observation data. The water penetration of snow plugs is also calculated, based on the heat balance. It takes 20 to 50 days for water to enter the blocked tunnel. The empirical values are 30 to 60 days, but only 1 day if the temperature of the snow pack is 0{sup o}C. Sensitivity analyses are carried out for temperature variations in rock, snow, water and ice. Systematic field observation shows that it is important for hydropower companies to know about the effects of snow and ice blocking in an area. A risk analysis of dam safety is presented for a real case. Finally, the thesis proposes solutions which can reduce the snow and ice problems. 79 refs., 63 figs., 11 tabs.

  20. An Assessment of the Icing Blade and the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

    Science.gov (United States)

    Steen, Laura E.; Ide, Robert F.; Van Zante, Judith Foss

    2017-01-01

    The Icing Research Tunnel at NASA Glenn has recently switched to from using the Icing Blade to using the SEA Multi-Element Sensor (also known as the multi-wire) for its calibration of cloud liquid water content. In order to perform this transition, tests were completed to compare the Multi-Element Sensor to the Icing Blade, particularly with respect to liquid water content, airspeed, and drop size. The two instruments were found to compare well for the majority of Appendix C conditions. However, it was discovered that the Icing Blade under-measures when the conditions approach the Ludlam Limit. This paper also describes data processing procedures for the Multi-Element Sensor in the IRT, including collection efficiency corrections, mounting underneath a splitter plate, and correcting for a jump in the compensation wire power. Further data is presented to describe the repeatability of the IRT with the Multi-Element sensor, health-monitoring checks for the instrument, and a sensing-element configuration comparison.

  1. Some Caves in tunnels in Dinaric karst of Croatia

    Science.gov (United States)

    Garasic, Mladen; Garasic, Davor

    2016-04-01

    In the last 50 years during the construction of almost all the tunnels in the Croatian Dinaric Karst thousands of caves have been encountered that represented the major problems during the construction works. Geological features (fissures, folding, faults, etc.) are described in this contribution, together with the hydrogeological conditions (rapid changes in groundwater levels). Special engineering geological exploration and survey of each cave, together with the stabilization of the tunnel ceiling, and groundwater protection actions according to basic engineering geological parameters are also presented. In karst tunneling in Croatia over 150 caves longer than 500 m have been investigated. Several caves are over 300 m deep (St. Ilija tunnel in Biokovo Mt), and 10 are longer than 1000 m (St.Rok tunnel, HE Senj and HE Velebit tunnels in Velebit Mt, Ucka tunnel in Ucka Mt, Mala kapela tunnel in Kapela Mt, caverns in HE Plat tunnel etc). Different solutions were chosen to cross the caves depending on the size and purpose of the tunnels (road, rail, pedestrian tunnel, or hydrotechnical tunnels). This is presentations of interesting examples of ceiling stabilization in big cave chambers, construction of bridges inside tunnels, deviations of tunnels, filling caves, grouting, etc. A complex type of karstification has been found in the cavern at the contact between the Palaeozoic clastic impervious formations and the Mesozoic complex of dolomitic limestones in the Vrata Tunnel and at the contact with flysch in the Učka Tunnel. However, karstification advancing in all directions at a similar rate is quite rare. The need to have the roadway and/or tunnel above water from a spring is the biggest possible engineering-geological, hydrogeological and civil engineering challenge. Significant examples are those above the Jadro spring (Mravinci tunnel) in flysch materials or above the Zvir spring in Rijeka (Katarina tunnel), and in fractured Mesozoic carbonates. Today in Croatian

  2. Electron tunnel sensor technology

    Science.gov (United States)

    Waltman, S. B.; Kaiser, W. J.

    1989-01-01

    The recent development of Scanning Tunneling Microscopy technology allows the application of electron tunneling to position detectors for the first time. The vacuum tunnel junction is one of the most sensitive position detection mechanisms available. It is also compact, simple, and requires little power. A prototype accelerometer based on electron tunneling, and other sensor applications of this promising new technology are described.

  3. Measurements of water film characteristics on airfol surfaces from wind-tunnel tests with simulated heavy rain

    Science.gov (United States)

    Hastings, E. C., Jr.; Manuel, G. S.

    1985-01-01

    This paper discusses some of the surface water characteristics obtained during recent simulated heavy rain experiments conducted at the Langley Research Center. Water film distributions and discrete film thickness measurements on several model wings are discussed. The water film distributions on the upper surfaces are shown in photographs from cameras mounted above the models, and film thickness data are presented which were obtained using resistance sensors mounted flush with the upper and lower wing model surfaces. The paper also discusses potential sources of performance decrements indicated by the data.

  4. Source of salts in the Waianae part of the Pearl Harbor aquifer near Barbers Point water tunnel, Oahu, Hawaii

    Science.gov (United States)

    Eyre, P.R.

    1987-01-01

    The salinity of the water supply of Barbers Point Naval Air Station has increased markedly since 1983. The Naval Air Station obtains its water, about 3 million gal/day, from Barbers Point shaft, a water shaft that taps the Waianae part of the Pearl Harbor aquifer underlying the dry, southeastern flank of the Waianae mountains on the island on Oahu, Hawaii. From 1983 to 1985 the chloride concentration of the water, increased from 220 to 250 mg/L and has remained near that level through 1986. The EPA has established 250 mg/L as the maximum recommended chloride concentration in drinking water because above that level many people can taste the salt. The high chloride concentration in shallow groundwater at all wells in the area indicates that most of the salts in the freshwater lens are contributed by rainfall, sea spray, and irrigation return water. At Barbers Point shaft, pumping may draw a small amount of saltwater from the transition zone and increase the chloride concentration in the pumped water by about 20 mg/L. Salinity of the lens decreases progressively inland in response to recharge from relatively fresher water and in response to an increasing lens thickness with increasing distance from the shoreline. The increase, in 1983, in the chloride concentration of water at the shaft was most probably the result of saltier recharge water reaching the water table, and not the result of increased mixing of underlying saltwater with the freshwater. The chloride concentration of the recharge water has probably increased because, in 1980, the drip method of irrigation began to replace the furrow method on sugarcane fields near the shaft. A mixing-cell model was used to estimate the effect of drip irrigation on the chloride concentration of the groundwater in the vicinity of Barbers Point shaft. The model predicted an increase in chloride concentration of about 50 mg/L. The observed increase was about 30 mg/L and the chloride concentration is presently stable at 245 to

  5. Environmental Impact and Prediction of Gushing Water of Tonghai Tunnel Engineering,Yunnan Province,China%通海隧道施工涌突水灾害与环境影响研究

    Institute of Scientific and Technical Information of China (English)

    孙晋玉; 张强; 许模; 陈松

    2011-01-01

    通海隧道是中国云南国际铁路通道昆明-河口线上的主要工程,也是云南省在建的最长隧道。隧道全长10 302 m,全隧道为单面坡,最大坡度为20.4‰。该隧道在通海县境邻近杞麓湖,作为通海县重要的水资源,杞麓湖具有工农业用水、调蓄、防洪、航运、旅游、水产养殖等功能,是通海县社会经济发展的主体。隧道施工以来,在进出口的数个出水点涌出大量的地下水,由于工程区为生态敏感的岩溶地区,因此亟需查明隧道涌水与周边杞麓湖等水体的水力联系。通过对隧址区岩溶水文地质条件的研究,在充分了解区域构造环境、褶皱与断裂特征、掌握地下水含%Tonghai tunnel is 10.302 km long,which is a super long tunnel on the Kunming-Hekou international railway now under construction.As the tunnel is near by the Qilu Lake,which is the main water source of Tonghai Country,thus the detection of the hydraulic connection between the tunnel and Qilu lake is essential.This paper outlines karst hydro-geologic conditions and the investigation of the regional tectonic environment,folds and fractures,main aquifers and their water-rich characteristics,underground water recharge,runoff,and drainage conditions plus the hydro-geologic units of the tunnel area.Combined with gushing water conditions in tunnel construction process and geological condition in excavated sections,the source of gushing water and its hydraulic connection with Qilu Lake has been detected,the environmental impact of gushing water has been analyzed.

  6. 南水北调西线一期工程中的长深引水隧洞%LONG AND DEEP DIVERSION TUNNELS OF 1ST STAGE PROJECT IN WEST ROUTE OF SOUTH-NORTH WATER TRANSFER PROJECT

    Institute of Scientific and Technical Information of China (English)

    沈凤生; 刘新

    2003-01-01

    West Route of South-North Water Transfer Project,situated in southeastern Qinghai-Tibet Plateau,is a giant project,which will deliver 17 billion m3 of water from the main stream and tributaries upstream of the Yangtze River to the upper reaches of the Yellow River. It is to be constructed in 3 stages, of which the 1st stage project includes delivering 4 billion m3 of water by gravity from two tributaries of Yalong River and three tributaries of Dadu River. The project consists of 5 dams,7 tunnels and a channel in series,with the dam height of 63~123 m and water transfer length of 260.3 km,of which the tunnels measure 244.1 km. The special climatic,environmental and geologic conditions make the project much more complicated in construction,especially 3 tunnels with the length longer than 50 km each create challenges to the technical requirements of engineering survey,design and construction.

  7. Construction scheme at gushing water section of No.3 inclined shaft in Guanjiao tunnel%关角隧道三号斜井涌水段施工方案

    Institute of Scientific and Technical Information of China (English)

    李亮

    2012-01-01

    The author carries on gushing water measurement on the construction of No.3 inclined shaft in Guanjiao tunnel,summarizes specific construction gushing water processing principles according to actual conditions,and puts forward drainage design scheme and radial pouring construction scheme,so as to guarantee smooth tunnel construction.%对关角隧道三号斜井的施工涌水量进行了实际测量,根据实际情况归纳出了施工涌水的具体处理原则,提出了排水设计方案及径向注浆施工方案,以确保隧道施工的顺利进行。

  8. Quantum tunneling during interstellar surface-catalyzed formation of water: the reaction H + H$_2$O$_2$ $\\rightarrow$ H$_2$O + OH

    CERN Document Server

    Lamberts, Thanja; Köhn, Andreas; Kästner, Johannes

    2016-01-01

    The final step of the water formation network on interstellar grain surfaces starting from the H + O$_2$ route is the reaction between H and H$_2$O$_2$. This reaction is known to have a high activation energy and therefore at low temperatures it can only proceed via tunneling. To date, however, no rate constants are available at temperatures below 200 K. In this work, we use instanton theory to compute rate constants for the title reaction with and without isotopic substitutions down to temperatures of 50 K. The calculations are based on density functional theory, with additional benchmarks for the activation energy using unrestricted single-reference and multireference coupled-cluster single-point energies. Gas-phase bimolecular rate constants are calculated and compared with available experimental data not only for H + H$_2$O$_2$ $\\rightarrow$ H$_2$O + OH, but also for H + H$_2$O$_2$ $\\rightarrow$ H$_2$ + HO$_2$. We find a branching ratio where the title reaction is favored by at least two orders of magnitu...

  9. In Situ Observation of Water Dissociation with Lattice Incorporation at FeO Particle Edges Using Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Xingyi [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Lee, Junseok [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Wang, Congjun [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Matranga, Christopher [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Aksoy, Funda [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Nigde University, Nigde (Turkey). Dept. of Physics; Liu, Zhi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2011-03-15

    The dissociation of H2O and formation of adsorbed hydroxyl groups, on FeO particles grown on Au(111) were identified with in situ,: X:ray photoelectron spectroscopy (XPS) at water pressures ranging from 3 x 10-8 to 0.1 Torr. The facile dissociation of H2O takes place at FeO particle edges, and it was successfully observed in situ With atomically resolved scanning tunneling microscopy (STM). The in situ STM studies show that adsorbed hydroxyl groups were formed exclusively along the edges of the FeO particles with the 0 atom becoming directly incorporated into the oxide crystalline lattice The STM results are consistent with coordinatively unsaturated ferrous (CUF) sites along the FeO particle edge causing the observed reactivity with H2O. Our results also directly illustrate how structural defects and under.-coordinated sites participate in chemical reactions.

  10. Tunnel Waterproofing with Membranes Waterproofing at Senoko Cabele Tunnel in comparison with International Standards

    Institute of Scientific and Technical Information of China (English)

    Stefan Hotz

    2004-01-01

    Waterproofing of tunnels is and has always been a challenge, worldwide: Changing Geology with hardly predictable water inflow, limited space underground and only very little intervention opportunities once the tunnel is completed. This paper elaborates such challenges and focuses on the waterproofing solutions of mined tunnels with membranes. Different standards and approaches for the waterproofing system. In Singapore, a membrane waterproofing system is used for the shafts and adits at Senoko Cable Tunnel. The paper project specific waterproofing challenges and emphasizes on solution for them.

  11. Research on distribution of initial excess pore water pressure due to shield tunnelling%盾构隧道施工引起的土体初始超孔隙水压力分布研究

    Institute of Scientific and Technical Information of China (English)

    魏新江; 陈伟军; 魏纲; 洪杰

    2012-01-01

    Excess pore water pressure is generated during shield tunnelling, resulting in consolidation settlement. Assuming the disturbance range shape of shield tunnelling is circular arc, the distribution range of excess pore water pressure is determined. The formula of initial excess pore water pressure of soil around tunnel lining is deduced by stress relief theory; and the formula of initial excess pore water pressure of soil within the region of its distribution at any point is subsequently deduced by stress transfer theory. By comparing calculated and measured data, it is shown that they are in good agreement. Based on practical example, a conclusion is drawn that the distribution shape of initial excess pore water pressure of soil around shield tunnel circle is roughly circular (top of small, bottom of large). With the increase of distance from shield tunnel central axis, the initial excess pore water pressure of soil shows a concave curve shape. At the same time, the isopleths at the bottom of shield tunnel changes fastest. Above the top of the tunnel, the initial excess pore water pressure of soil gets the maximum at the tunnel axis in different depths, showing a similar Peck shape.%盾构施工会对周围土体产生扰动,形成超孔隙水压力,引起工后固结沉降.运用应力释放理论推导与衬砌相邻的土体初始超孔隙水压力计算公式.假定扰动范围边界呈圆弧状,确定初始超孔隙水压力的分布范围;同时运用应力传递理论,推导分布范围内任一点土体的初始超孔隙水压力计算公式.通过对实测资料的分析可知,计算值与实测值吻合较好.算例分析表明,与衬砌相邻的土体初始超孔隙水压力呈近似圆形(顶部小、底部大);随着到衬砌的径向距离增加,土体初始超孔隙水压力呈凹曲线形状;隧道底部的等值线最密,即变化最快:隧道顶部上方土体、不同深度处土体初始超孔隙水压力,以隧道轴线处为最大,呈现类似Peck曲线形状.

  12. 梁山隧道深埋富水陡倾软弱带突水涌泥机制分析及旋喷技术%Analysis on Mechanism of Water Gushing and Mud Inflow When Tunneling through Deep-covered Steep Water-rich Fracture Zone and Application of Horizontal Jet Grouting Piles:Case Study on Liangshan Tunnel

    Institute of Scientific and Technical Information of China (English)

    吴培荣

    2015-01-01

    Liangshan tunnel is one of the key works on Xiamen-Shenzhen railway.During the construction of the tunnel, water gushing and mud inflow often occur,due to the deep-covered water-rich steep soft fracture zone met.In the paper, the characteristics of the water gushing,mud inflow and ground surface collapse are studied,and the water gushing and mud inflow mechanism is analyzed.It is concluded that fully-weathered materials and ground water under the effect of high seepage pressure difference induced by tunnel excavation are the main causes for the water gushing and mud inflow, and that the ground surface collapse is induced by the sudden drop of the ground water level.After investigation, theoretical analysis and tests,it is determined that long-distance horizontal jet grouting piles be used to reinforce the fracture zone.The layout,construction process and inspection standard of the jet grouting piles are also presented in the paper.The practice shows that the long-distance horizontal jet grouting piles mentioned are feasible and effective in the consolidation of the fracture zone.%梁山隧道是厦深铁路福建段的控制工程之一,施工中遇到深埋富水陡倾软弱带,多次导致突水涌泥及洞顶塌陷情况。通过研究突水涌泥及洞顶塌陷的灾害特征,分析得到突水涌泥机制,即:在这种多因素复杂地质条件下,隧道开挖导致形成极高的渗透压力差,并产生新的地下临空通道,在地下水渗透压力作用和自身重力作用下,全风化物质涌入隧道,形成突水涌泥;而软弱构造带塌陷的主要原因为地下水位的急剧下降。通过调研、理论分析及试验等方法,确定采用长距离水平旋喷桩通过软弱带,并提出其布置形式、施工工艺及检验标准。工程实践证明,采用长距离水平旋喷桩作为预加固手段是可行且有效的。

  13. On the use of Li isotopes as a proxy for water-rock interaction in fractured crystalline rocks: A case study from the Gotthard rail base tunnel

    Science.gov (United States)

    Wanner, Christoph; Bucher, Kurt; Pogge von Strandmann, Philip A. E.; Waber, H. Niklaus; Pettke, Thomas

    2017-02-01

    We present Li isotope measurements of groundwater samples collected during drilling of the 57 km long Gotthard rail base tunnel in Switzerland, to explore the use of Li isotope measurements for tracking water-rock interactions in fractured crystalline rocks at temperatures of up to 43 °C. The 17 groundwater samples originate from water-conducting fractures within two specific crystalline rock units, which are characterized by a similar rock mineralogy, but significantly different fluid composition. In particular, the aqueous Li concentrations observed in samples from the two units vary from 1-4 mg/L to 0.01-0.02 mg/L. Whereas δ7Li values from the unit with high Li concentrations are basically constant (δ7Li = 8.5-9.1‰), prominent variations are recorded for the samples from the unit with low Li concentrations (δ7Li = 10-41‰). This observation demonstrates that Li isotope fractionation can be highly sensitive to aqueous Li concentrations. Moreover, δ7Li values from the unit with low Li concentrations correlate well with reaction progress parameters such as pH and [Li]/[Na] ratios, suggesting that δ7Li values are mainly controlled by the residence time of the fracture groundwater. Consequently, 1D reactive transport modeling was performed to simulate mineral reactions and associated Li isotope fractionation along a water-conducting fracture system using the code TOUGHREACT. Modeling results confirm the residence time hypothesis and demonstrate that the absence of δ7Li variation at high Li concentrations can be well explained by limitation of the amount of Li that is incorporated into secondary minerals. Modeling results also suggest that Li uptake by kaolinite forms the key process to cause Li isotope fractionation in the investigated alkaline system (pH >9), and that under slow flow conditions (mineral reaction rates if more thermodynamic data about the temperature-dependent incorporation of Li in secondary minerals as well as corresponding fractionation

  14. Treatment measures for underground water leakage during construction of tunnel in metamorphic soft rock%变质软岩隧道施工中地下水渗漏处治措施

    Institute of Scientific and Technical Information of China (English)

    李皓晖; 左昌群; 唐霞; 丁少林; 刘代国

    2015-01-01

    Due to the metamorphic soft rock characteristics of water softening and disintegration,there is the phenomenon such as groundwater seepage and water inflow in tunnel construction,which could bring huge hidden danger to the tunnel construction safety. T aking the typical groundwater seepage zone of W udang group schist tunnel in Shiyan-fangxian expressway as research object,in this paper,the groundwater seepage effect in metamorphic soft rock tunnel construction w as analyzed from the aspects including groundw ater seepage characteristics of disaster section,water rationality of surrounding rock,physical mechanics function of groundwater,and put forward the specific control measures of groundwater. T he practice showed that the measures presented in this paper has good control effect on groundw ater leakage of soft rock tunnel,w hich could provide a reference for w atery section safe construction of similar soft rock tunnel.%由于变质软岩具有遇水软化、崩解的特征,在隧道施工过程中易出现地下水渗漏、涌水等,给隧道施工安全带来巨大隐患。以十堰至房县高速公路武当群片岩隧道中典型地下水渗漏区段为主要研究对象,从灾害段地下水渗漏特征、围岩的水理性、地下水的物理力学作用等方面阐述了变质软岩隧道施工中地下水渗漏的影响,并提出了有针对性的地下水控制措施。实践证明,该措施对软岩隧道地下水渗漏具有较好的控制作用,可为类似软岩隧道富水段安全施工提供参考。

  15. Hypersonic Tunnel Facility (HTF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Hypersonic Tunnel Facility (HTF) is a blow-down, non-vitiated (clean air) free-jet wind tunnel capable of testing large-scale, propulsion systems at Mach 5, 6,...

  16. Transonic Dynamics Tunnel (TDT)

    Data.gov (United States)

    Federal Laboratory Consortium — The Transonic Dynamics Tunnel (TDT) is a continuous flow wind-tunnel facility capable of speeds up to Mach 1.2 at stagnation pressures up to one atmosphere. The TDT...

  17. Road and Railroad Tunnels

    Data.gov (United States)

    Department of Homeland Security — Tunnels in the United States According to the HSIP Tiger Team Report, a tunnel is defined as a linear underground passageway open at both ends. This dataset is based...

  18. Quantum theory of tunneling

    CERN Document Server

    Razavy, Mohsen

    2014-01-01

    In this revised and expanded edition, in addition to a comprehensible introduction to the theoretical foundations of quantum tunneling based on different methods of formulating and solving tunneling problems, different semiclassical approximations for multidimensional systems are presented. Particular attention is given to the tunneling of composite systems, with examples taken from molecular tunneling and also from nuclear reactions. The interesting and puzzling features of tunneling times are given extensive coverage, and the possibility of measurement of these times with quantum clocks are critically examined. In addition by considering the analogy between evanescent waves in waveguides and in quantum tunneling, the times related to electromagnetic wave propagation have been used to explain certain aspects of quantum tunneling times. These topics are treated in both non-relativistic as well as relativistic regimes. Finally, a large number of examples of tunneling in atomic, molecular, condensed matter and ...

  19. Hypersonic Tunnel Facility (HTF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Hypersonic Tunnel Facility (HTF) is a blow-down, non-vitiated (clean air) free-jet wind tunnel capable of testing large-scale, propulsion systems at Mach 5, 6,...

  20. 海底取水盾构隧道管片力学性状的数值研究%Numerical analysis of mechanical behaviors of segments of subsea shield tunnel for water intake

    Institute of Scientific and Technical Information of China (English)

    钟润辉; 王立忠; 王湛; 王体

    2012-01-01

    A three-dimensional solid model was adopted to analyze the standard segment of Sanmen nuclear power station' s water intake tunnel which was staggered joint assembling per eight rings in order to analyze the different mechanical behaviors of subsea water intake tunnel's segments between construction and operation. The segments were modeled by solid elements, the bolts were modeled by beam elements, and the contact role of joints was considered. The numerical results indicated that the diameter deformation of water intake tunnel in operation was 1. 5 times larger than in construction, with the maximum positive moment increasing 44, 4%, the internal force of circumferential bolt rising nearly 11 times, and the splaying amount of joints soaring up to nearly 9 times. When tunnel was staggered joint assembling per eight rings, key block's location would affect the distribution of internal force of segments. During the operation period, the maximum of positive moment of crown was 2. 22 times larger than the minimum. For the water intake tunnel, operation with water stress is design control load case.%为了研究海底取水隧道管片在施工和运行过程中力学性状的不同,采用三维实体模型对国内首次采用八环错缝拼装的三门核电取水隧道标准段进行分析.模型中管片采用实体单元模拟,螺栓采用梁单元模拟,充分考虑各接缝间的接触作用.计算结果表明,与施工阶段相比,运行期整体直径变形增大了1.5倍,最大正弯矩增大了44.4%,环向螺栓受力增大了近11倍,各接缝张开量增大了近9倍.八环错缝拼装时,关键块位置的改变将在一定程度上影响各环的内力分布,运行期各环拱顶处正弯矩最大值是最小值的2.22倍.对于取水隧道而言,运行期充水工况是控制工况.

  1. The Tunnels of Samos

    Science.gov (United States)

    Apostol, Tom M. (Editor)

    1995-01-01

    This 'Project Mathematics' series video from CalTech presents the tunnel of Samos, a famous underground aquaduct tunnel located near the capital of Pithagorion (named after the famed Greek mathematician, Pythagoras, who lived there), on one of the Greek islands. This tunnel was constructed around 600 BC by King Samos and was built under a nearby mountain. Through film footage and computer animation, the mathematical principles and concepts of why and how this aquaduct tunnel was built are explained.

  2. Magnetic tunnel junctions (MTJs)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We review the giant tunnel magnetoresistance (TMR) in ferromagnetic-insulator-ferromagnetic junctions discovered in recent years, which is the magnetoresistance (MR) associated with the spin-dependent tunneling between two ferromagnetic metal films separated by an insulating thin tunnel barrier. The theoretical and experimental results including junction conductance, magnetoresistance and their temperature and bias dependences are described.

  3. 管节接头OMEGA止水带安装工艺%Technology for installation of OMEGA water- stops injoints of immersed tunnel sections for Hongkong- Zhuhai- Macao Bridge

    Institute of Scientific and Technical Information of China (English)

    周建民; 唐永波; 魏杰

    2016-01-01

    为确保沉管接头OMEGA止水带水密质量及120 a使用寿命,根据港珠澳大桥岛隧工程技术标准及沉管接头OMEGA止水带的施工要求,制定了一套适合的工艺方案,详细叙述了OMEGA止水带的安装步骤及注意事项。对类似工程具有一定的参考价值。%In order to insure the watertight quality of OMEGA waterstop and it's service life of 120 years for immersed tunnel sections, a suitable technological plan for installation was formulated according to the technical standard for the island&tunnel project of Hongkong-Zhuhai-Macao Bridges and the installation requirements for OMEGA water-stops in the joints for immersed tunnel section. The paper expounds on the procedures for installation of the OMEGA water-stopsand the precautions to be taken during the installation, providing reference for similar projects.

  4. The Application of Temperature-Measuring to the Forecast of Gush Water Inside the Shilin Tunnel%温度量测在石林隧道突水预报中的应用

    Institute of Scientific and Technical Information of China (English)

    史付生

    2012-01-01

    The use of the gradient measuring of temperatures for the forecast of gush water inside tunnels is dealt with in the pa- per, with the basic principle of the use of the change in the temperature of the working face for the forecast of gush water or gush earth presented and discussed. With the project of the Shilin Tunnel as a practical example, the practical steps and effects of the method are introduced, which may serve as a new approach to the advanced forecast of the geological conditions inside tunnels.%提出了用温度梯度量测预报隧道突水。阐述了利用掌子面温度变化预报隧道突泥突水的基本原理;结合石林隧道的工程实践,介绍了该方法的实施步骤和效果。为超前地质预报提供了一个新的途径。

  5. 水蚀对风蚀影响的室内模拟试验%Effects of Water Erosion on Wind Erosion in Wind Tunnel

    Institute of Scientific and Technical Information of China (English)

    张庆印; 樊军; 张晓萍

    2012-01-01

    为了揭示黄土高原水蚀风蚀交错区风水复合侵蚀机制,利用室内风洞,在一定的风速(9.3m/s)、坡度(20°)下,人工模拟不同沟宽、沟深、沟密度对风蚀过程的影响。结果表明,在一定的水蚀沟宽度与密度范围内,风蚀量随着宽度与密度的增加而增加,并且两者与风蚀量都呈线性关系;侵蚀沟深度在4~8cm范围内,风蚀量随着沟深度增加而增加,当沟深大于8cm时,随着沟深度增加,风蚀量有所减少;水蚀沟发生风蚀的部位主要在沟壁和沟头,风沙流的磨蚀作用可能是主要作用力,水蚀沟形成会显著影响风蚀量。%Effect of water erosion on wind erosion was studied by wind tunnel under the different width,depth and density of rill under the condition of wind speed(9.3 m/s) and steep slope(20°) in order to reveal the mechanism of aeolian-fluvial interaction in the water-wind erosion crisscross region on the Loess Plateau.The results show that the sediment yields of wind erosion increased with the rill width and density during the certain range,and the sediment yields of wind erosion presented a positive relation with the rill width and density;in the 4~8 cm range,the sediment yields of wind erosion increased with the depth,while decreased when the depth was over 8 cm.Wall and foreside of rill were eroded easily by wind and the abrasive action of sand-driving wind may be the main force.The width,density and depth of rill were the key factors to influence the sediment yields of wind erosion,therefore,wind erosion was affected significantly by water erosion.

  6. HYDRAULIC RESEARCH OF AERATORS ON TUNNEL SPILLWAYS

    Institute of Scientific and Technical Information of China (English)

    RUAN Shi-ping; WU Jian-hua; WU Wei-wei; XI Ru-ze

    2007-01-01

    The selection of the configuration and size of an aerator was of importance for a tunnel spillway under the conditions of high speed flows. Experimental investigations were conducted on the effects of entrained air on the tunnel spillway in the Goupitan Project, based on the criterion of gravity similarity and the condition of aerated flow velocity of over 6 m/s, with physical models. The configurations of the aerators were presented of a larger bottom air concentration, to protect the tunnel spillway from cavitation as well as to see no water fills in the grooves.

  7. 田坝岭隧道进口D3K426+477突水处理措施%Water Gushing Measures for Tianbaling Tunnel Import D3K426+477

    Institute of Scientific and Technical Information of China (English)

    张品

    2014-01-01

    Relying on new TianBaLing tunnel engineering fr-om GuiYang to GuangZhou railway, this article introduces the situation of water gushing at TianBaLing tunnel import D3K-426+477, emergency treatment measures on-site and subsequ-ent processing measures.%本文依托新建贵阳至广州铁路田坝岭隧道工程,介绍了田坝岭隧道进口D3K426+477的突水情况、现场紧急处理措施和后续处理措施。

  8. Proton tunneling in solids

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, J.

    1998-10-01

    The tunneling rate of the proton and its isotopes between interstitial sites in solids is studied theoretically. The phonons and/or the electrons in the solid have two effects on the tunneling phenomenon. First, they suppress the transfer integral between two neighbouring states. Second, they give rise to a finite lifetime of the proton state. Usually the second effect is large and the tunneling probability per unit time (tunneling rate) can be defined. In some cases, however, a coherent tunneling is expected and actually observed. (author)

  9. 深长隧道涌水量预测影响因素评价分析%Analysis on affecting factors in prediction of gushing water volume in deep-buried and long tunnel

    Institute of Scientific and Technical Information of China (English)

    李显伟

    2014-01-01

    The water inflow in tunnel is in concerned with its construction , its characteristics and the hydrogeological environment it locates in .In this light,an accurate prediction of the gushing water volume is premised on the wise selection and analysis of major influential factors .The paper reviews in detail the geological and hydrological environment the deep-buried and long tunnels in China surrounded by .Based on this,the analytic hierarchy process is used ,in the effort of building an assessment model to quantify all the influential factors that affect the gushing water volume in deep-buried and long tunnel .The results indicate that the lithologic characters and the water-rich property of the stratum , the type of the underground water , the geological structure , the topography , the annual average precipitation are all identified as key parameters .Hopefully , the paper can be of scientific use for the perdiction of gushing water volume in deep-buried and long tunnel .%隧道涌水不但与施工条件和隧道特征有关,而且受到水文地质条件的影响,对影响隧道涌水的主要因素的遴选和分析是准确进行隧道涌水量预测的前提。对我国深长隧道地质与水文地质条件进行详细分析,采用层次分析法建立深长隧道涌水量影响因素评价模型,定量确定了各因素的权重。研究结果表明:地层岩性、岩层富水性、地下水类型、地质构造、地形地貌和年均降水量是影响深长隧道涌水量的关键因素。本文分析结果为深长隧道涌水量预测分析提供了科学依据。

  10. Use of heat from the drainage water at the southern end of the Gotthard low-level rail tunnel - Feasibility study, phase II; Waermenutzung Tunnelwasser Basistunnel Gotthard, Suedportal. Machbarkeitsstudie Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Dups, Ch.

    2004-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) discusses the possibilities of using the drainage water at the southern end of the Gotthard low-level railway tunnel in Switzerland as a source of heat for several possible projects. The drainage water, estimated at 80 - 460 litres per second at a temperature of 30 - 35 {sup o}C, could possibly be used for heating greenhouses, providing a combined tropical greenhouse and fish farm, heating a wellness-spa, or for district heating or the heating of particular buildings. The thermal use of the water and its further use as drinking water is also considered. Figures on energy yields and costs are presented and estimates of the savings in fossil fuels and carbon dioxide emissions are quoted.

  11. Analysis on Causes of Large-scale Water Gushed from Tunnel Floor and Countermeasures%某隧道底板大规模突水原因分析与处治技术

    Institute of Scientific and Technical Information of China (English)

    焦雷; 邹罛; 徐海廷

    2016-01-01

    A large-scale water gushed from tunnel floor due to the ample water supply on the ground surface during the construction of a tunnel crossing the contact zone between fracture evaporite solution breccia and complete gypsum layer, which brought serious destructions and threatens to the surrounding environments.As a result,some effective measures have to be took to control water gushing.In this paper,comparison and contrast is made among several grouting methods.With the treating principle of “drainage first and then sealing,radial grouting reinforcement first and then tunnel floor sealing,and centralized treatment of local part”,the water gushing speed is slowed down,the surrounding rock permeability coefficient is reduced,the tunnel structure stability is improved and the ground water is brought under effective control by using radial grouting and deep-hole grouting.%某隧道在穿越破碎盐溶角砾岩与完整石膏夹层接触带时,由于充足的地表水源和良好的补给通道,引发隧道底部3800 m3/h的大规模突水,给周边环境和施工安全造成严重破坏和威胁。如何有效的处治隧道底部如此大的突水,控制施工风险和保证隧道结构稳定成为最关键的技术问题。经过多种方案对比研究,通过“先引后堵、先径向加固再底板封堵、先易后难局部集中处理”的总体步骤,实现了隧道底部突水由快速流动状态到相对静止状态的转变,为隧道底部注浆堵水提供施作条件,再通过径向注浆和深孔底板注浆降低围岩的渗透系数和提高隧道结构稳定性,控制地下水流失,不给通车运营留下质量和安全隐患。

  12. On the Treatment of Water Gushing of Maijishan Tunnel 2# Inclined Well and Reverse Slope Drainage Programme%麦积山隧道2#斜井涌水处理及反坡排水方案浅谈

    Institute of Scientific and Technical Information of China (English)

    袁振华

    2014-01-01

    There appeared large quantity of water gushing and concentrated water flowing, and the combination of reverse slope drainage and post grouting water plugging is used to effectively divert, intercept, drain and plug water, minimize the effect of water gushing of the tunnel, and effectively improve the construction efficiency, the key point of reverse slope drainage is setting up the location of pumping station reasonably according to the actual site, equipping with enough pumping and drainage equipment as deeded, and taking maximum water flowing into full consideration and preparing drainage capacity to flexiblely and timely treat the effects of water increases on tunnel digging. Combined with water gushing and constantly optimization and adjustment of the construction programme and drainage facilities of Maijishan tunnel 2# inclined well of Baoji-Lanzhou passenger dedicated line, this paper summarizes a construction method that applies to the treatment of water gushing.%隧道出现大的涌水和集中出水,采用反坡排水和后注浆堵水相结合的方式,对出水做到有效地“引、截、排、堵”,将隧道涌水对施工进度的影响降到最低,有效提高施工工效,反坡排水重点是根据现场实际合理设置泵站位置,按需配备足够的抽排水设备并充分考虑最大出水可能预备排水能力,以便灵活、及时地处理出水增大对隧道掘进的影响;本文结合宝兰客运专线铁路麦积山隧道2#斜井施工出现涌水及处理过程中施工方案和排水设施配置的不断优化调整,总结出的一套适用于隧道涌水处理的施工方法。

  13. 田阳县那坡镇宝美村龙达屯水利配套工程隧洞设计%The Tunnel Design of Water & Power Auxiliary Project in Longda Village of Baomei Hamlet in Napo Town of Tianyang County

    Institute of Scientific and Technical Information of China (English)

    钟顺钠

    2013-01-01

    The paper introduces the tunnel condition of water&power auxiliary project in Longda village of Baomei hamlet in Napo town of Tianyang county, and explains the design description of the drainage tunnel.%  文章介绍了田阳县那坡镇宝美村龙达屯水利配套工程隧洞概况,并对其排涝隧洞进行设计说明。

  14. On Water Intake and Drainage Tunnel Optimization Design of Xiaba Reservoir of Guizhou Province%贵州下坝水库取水兼放空隧洞优化设计

    Institute of Scientific and Technical Information of China (English)

    张丹; 李伟

    2016-01-01

    针对下坝水库地形地貌、地质条件较复杂,受裂隙切割岩体较破碎,岩体强风化带完整性较差,易形成滑坡、崩塌、偏压、泥石流等问题,经现场踏勘,结合《水工隧洞建筑物设计规范》(SL386-2007),(SL279-2002)等,综合考虑工程占地、施工难度及工程投资等因素,优选“利用导流隧洞改为有压取水/放空隧洞”的一洞三用取放水方案。经水力计算、隧洞衬砌计算、应力稳定性复核等论证分析,隧洞建筑物结构、过流能力、衬砌裂缝宽度和稳定性等均满足规范要求,优化设计方案具有较高的技术可行性和经济合理性。%Aiming at the complex topography and geological conditions , the mass fractured rock by fissures cutting, the poor integrity of strong weathering zone which is easy to form landslides, collapse, unsymmet-rical pressure, debris flow and other problems in Xiaba reservoir, after the reconnaissance trip, combined with (SL386-2007), (SL279-2002),this paper takes overall consideration the engineering land occupation , the construction difficulty and the engineering invest-ment and other factors, optimal chooses the water intake and drainage scheme of reconstruction the diver-sion tunnel as the pressurized water taking/venting tunnel which can realize three function by one tunnel. From the hydraulic calculation, the tunnel lining calculation, the stress stability check and others analy-sis, the results showed that the structure, flow capacity, crack width and stress stability of the tunnel buildings can meet the standards requirements and the optimization design scheme has higher technical feasibility and economic rationality.

  15. 瘦西湖隧道下蜀黏土土水特征研究%Soil-water Characteristic of Xiashu Clay in Slender West Lake Tunnel

    Institute of Scientific and Technical Information of China (English)

    薛光桥

    2015-01-01

    土水特征曲线(SWCC)作为表征非饱和土吸力与含水率关系的重要参数是研究非饱和土的关键,对于膨胀土而言,土水特征曲线又是分析其膨胀性能的重要指标。本文以扬州瘦西湖隧道下蜀黏土为研究对象,通过大尺寸渗析法和气相法两种方法测量了其土水特征曲线,在低吸力范围内(0~160 MPa)曲线存在明显回滞现象。结合3种不同数学模型对曲线进行拟合分析,发现 Fredlund and Xing 公式拟合最为准确。利用扫描电镜分析了不同含水率条件下的细观特征,试验表明:随着含水率的增加,下蜀黏土中的蒙脱石颗粒不断吸水膨胀,从而填充土体孔隙。%Soil-water characteristic curve (SWCC)is the key to reflect the relationship between matric suction and mois-ture content of unsaturated soil.As for expansive soil,SWCC is also an important indicator to represent its expansion per-formance.In this paper,SWCC of Xiashu clay in Slender West Lake Tunnel of Yangzhou is measured by large size osmotic method and vapor phase technique,it shows obvious hysteresis phenomenon during lower matric suction (0 ~160MPa). Fitting it with three kinds of mathematical model,Fredlund and Xing formula is found to be matched best.The meso-char-acteristics under different moisture conditions are analyzed through scanning electron microscope.Tests show that with the increase of moisture content,montmorillonite granules are continuously expanding and thus the soil pores between them can be filled.

  16. 水下隧道火灾烟气数值模拟研究%The Simulation of Fire Smoke in the Tunnel under Water and the Analysis

    Institute of Scientific and Technical Information of China (English)

    梁晖; 李天立

    2012-01-01

    结合公路隧道火灾特点,利用FDS对某过江隧道中规模为20MW的火灾烟气进行了模拟计算。通过比较、分析和总结不同纵向通风风速条件下的隧道火灾烟气和温度的分布特点,得到了临界风速的模拟值及使得排烟效果最佳时的纵向风速,对隧道防排烟设计及火灾应急预案的制定具有参考意义。%This paper, combining the characteristics of a road tunnel fire, employs FDS to simulate the fire smoke of 20MW size in the Tunnel. Through the comparison, analysis and induction on the distribution characteristics of the smoke and the temperature under a different longitudinal ventilation velocity in a tunnel fire, the analog value of a critical ventilation and the analog value of a vertical ventilation which would be best for controling and sweeping the smoke were obtained. They supply the key to the design of a smoke management system in the Tunnel and are of sig- nificance in a fire emergency plan.

  17. 基于长期监测的高水压岩溶隧道二次衬砌水压特征研究%Study on Characteristics of Water Pressure on the Second Lining for High Water Level Karst Tunnel Based on Long Term Monitoring

    Institute of Scientific and Technical Information of China (English)

    申志军

    2015-01-01

    In this paper,based on long term tunnel lining water pressure monitoring for 4 typical high-risk karst tunnels in Yi-Wan railway line,the character of water pressure on the second lining of the karst tunnels was studied,together with model test and theory analysis.A generalized model for karst tunnel was put up to esti-mate water pressure on the second lining.The study showed:(1)The overall level of the measured water pres-sure on the second lining of each tunnel was low with the maximum of 0.13 MPa,far below 1 MPa,the design value of water pressure resistant lining .The distribution of water pressure of the cross section was significant-ly affected by tunnel drainage,while water pressure dynamic was closely related with rainy season.(2)The de-termination of the original water pressure of karst tunnel was controlled by drainage base level on or under the tunnel.The original water pressure was also related with drainage capacity and rainfall replenishment.The re-lease tunnel during construction formed the new drainage base level.(3)Only when there is drainage in tunnel, can the grouting reinforcement circle play the role of reducing water pressure on the lining.The water pressure on the second lining,inversely proportional to tunnel drainage(Q2 )and water seepage into the primary lining (Q1 ),was affected by Q2/Q1 .(4)As the successful drainage of the release tunnel has great influence on the wa-ter pressure on the second lining,scheduled check and maintenance should be done during the operation of the release tunnel to ensure smooth drainage.The study can provide a reference for the design and operation of high water level karst tunnel.%通过长期监测宜万铁路4座典型高风险岩溶隧道运营期衬砌水压,结合模型试验、理论分析研究岩溶隧道二次衬砌水压的特征,提出岩溶隧道衬砌水压计算的概化模型。研究表明:(1)各隧道实测衬砌水压总体值不大,最大0.13 MPa,低于1 MPa抗水压衬砌设计值;断

  18. Comprehensive Construction Techniques for a Tunnel in Water-soaked Gravel and Sand%砂卵石地层出水隧道施工综合技术

    Institute of Scientific and Technical Information of China (English)

    哈吉章; 黄威望; 邵大鹏

    2011-01-01

    文章阐述了甘谷墩隧道砂卵石地质出水段采用的增加初喷混凝土厚度、减小钢架间距、拱脚处加设锁脚锚管及全断面注水泥-水玻璃双液浆等加强初期支护的施工措施;通过对开挖支护效果的分析,总结了砂卵石地层出水段施工综合技术.%Parameters of primary support was improved by increaing initial shotcret thickness, reducing steel frame intervals,setting locking anchor pipes at arch abutments and full-face composite grouting with cement and water glass for the water-soaked gravel and sand section in Gangudun tunnel. Construction techniques of the tunnel in water-soaked gravel and sand is summarized after analyzing the effect of support.

  19. 确定性数学模型方法预测隧道涌水量研究%Study on deterministic mathematical model for predicting water gushing yield of tunnel

    Institute of Scientific and Technical Information of China (English)

    姜爱民; 杨辉; 张明

    2012-01-01

    In this paper, the deterministic mathematical model for predicting the amount of water gushing in tunnel is introduced, and the common used methods are discussed. It is considered that the numerical simulation is the effective way to predict the amount of water gushing. Based on finite element numerical method, the water gushed yield is predicted in Nanliang tunnel of Shijiazhuang to Taiyuan special railway line. The results show that the predicted results are basically consistent with the actual situation.%本文介绍了确定性数学模型预测隧道涌水量的常用方法,认为数值模拟方法是隧道涌水量预测的有效方法。并基于有限单元数值法对石太客运专线南梁隧道可能集中涌水区段进行了预测,结果表明其预测结果与实际情况基本吻合。

  20. Resonance Enhanced Tunneling

    CERN Document Server

    Matsumoto, S; Matsumoto, Sh.

    2000-01-01

    Time evolution of tunneling in thermal medium is examined using the real-time semiclassical formalism previously developed. Effect of anharmonic terms in the potential well is shown to give a new mechanism of resonance enhanced tunneling. If the friction from environment is small enough, this mechanism may give a very large enhancement for the tunneling rate. The case of the asymmetric wine bottle potential is worked out in detail.

  1. Tunnelling in Dante's Inferno

    Science.gov (United States)

    Furuuchi, Kazuyuki; Sperling, Marcus

    2017-05-01

    We study quantum tunnelling in Dante's Inferno model of large field inflation. Such a tunnelling process, which will terminate inflation, becomes problematic if the tunnelling rate is rapid compared to the Hubble time scale at the time of inflation. Consequently, we constrain the parameter space of Dante's Inferno model by demanding a suppressed tunnelling rate during inflation. The constraints are derived and explicit numerical bounds are provided for representative examples. Our considerations are at the level of an effective field theory; hence, the presented constraints have to hold regardless of any UV completion.

  2. Microsystem Aeromechanics Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — The Microsystem Aeromechanics Wind Tunnel advances the study of fundamental flow physics relevant to micro air vehicle (MAV) flight and assesses vehicle performance...

  3. Ulnar tunnel syndrome.

    Science.gov (United States)

    Bachoura, Abdo; Jacoby, Sidney M

    2012-10-01

    Ulnar tunnel syndrome could be broadly defined as a compressive neuropathy of the ulnar nerve at the level of the wrist. The ulnar tunnel, or Guyon's canal, has a complex and variable anatomy. Various factors may precipitate the onset of ulnar tunnel syndrome. Patient presentation depends on the anatomic zone of ulnar nerve compression: zone I compression, motor and sensory signs and symptoms; zone II compression, isolated motor deficits; and zone III compression; purely sensory deficits. Conservative treatment such as activity modification may be helpful, but often, surgical exploration of the ulnar tunnel with subsequent ulnar nerve decompression is indicated.

  4. 盾构隧道近距离平行穿越原水管道沉降分析%Analysis on Settlement of Neighboring Distance of Shield Tunnel through Existing Water Pipe

    Institute of Scientific and Technical Information of China (English)

    王培利; 雷震宇; 周骏

    2015-01-01

    地铁盾构推进过程中会对隧道周围建(构)筑物和土层造成不同程度的影响。文章以上海轨道交通8号线某区间盾构隧道穿越既有原水管道为工程背景,应用ABAQUS有限元三维数值方法,分析盾构穿越既有原水管道时的原水管道沉降变形特征,分析不同施工参数对原水管道沉降的影响,并对既有原水管道沉降变形进行现场监测分析。计算和实测结果均表明原水管道沉降满足《上海市原水引水管渠保护办法》的规定要求。%In the process of shield tunneling, the construction of the surrounding buildings and the soil layer will be affected by the process of shield tunneling. Based on the ABAQUS fi nite element 3D method, the paper analyzes the characteristics of settlement deformation of the existing water pipeline in the original water pipeline by using ABAQUS finite element 3D method on the Shanghai Urban Transit Line 8, and analyzes the infl uence of different construction parameters on the settlement of existing water pipeline. The calculation and experimental results show that the original water pipes have met the requirements of the Protection Method for Shanghai City Source Water and Lead Water to Canal.

  5. Virtual photons in macroscopic tunneling

    CERN Document Server

    Aichmann, Horst; Bruney, Paul

    2015-01-01

    Tunnelling processes are thought to proceed via virtual waves due to observed superluminal (faster than light) signal speeds. Some assume such speeds must violate causality. These assumptions contradict, for instance, superluminally tunnelled music and optical tunnelling couplers applied in fiber communication. Recently tunnelling barriers were conjectured to be cavities, wherein the tunnelled output signal is not causally related with the input. The tests described here resolve that tunnelling waves are virtual, propagations are superluminal, and causality is preserved.

  6. 大瑞铁路保山隧道建设对易罗池岩溶水系统影响研究%Effects of Baoshan Tunnel Excavation on Yiluo Lake Karst Water System

    Institute of Scientific and Technical Information of China (English)

    李光伟; 杜宇本; 陈旭; 蒋良文

    2015-01-01

    The Baoshan tunnel on Dali-Ruili railway is seated between Baoshan basin and Nujiang river valley, passing through mountain area. The Yiluo Lake Spring is developed in the Karst water system and located in the west of Baoshan basin. For the purpose of avoiding engineering risk, this paper studies the formation mechanism of Yiluo Karst water system, analyzes the Karst hydraulic relationship of the Baoshan tunnel, evaluates the effects of Baoshan tunnel excavation on the Yiluo Lake Karst water system, as well as the rationality of proposed engineering measures. The Yiluo Karst water system is typically buried in Karst, develops in the limestone sandwich in the Dabaogai syncline, and supplemented with the upstream sand river water situated in Chaoyang village of the west of the syncline, runoffs among the limestone sandwich and discharges to the Yiluo Lake. The water system is characterized by confined water. The Baoshan tunnel is constructed through the limestone sandwich of the west of syncline, forming low surface with certain impact on the Karst system water pressure but with less reveal of the Karst water pipe. In order to avoid the engineering risk effectively, the research recommends such measures as well-established blocking ground water technique in the limestone sandwich of the west of syncline in the process of design and construction.%大瑞铁路保山隧道为穿越保山盆地和怒江峡谷间的越岭隧道,易罗池泉水为保山盆地西侧边缘岩溶大泉。通过区内地质构造、地层岩性和水动力条件的分析,对易罗池岩溶水系统形成机制进行研究,认为易罗池岩溶水系统沿大宝盖向斜灰岩夹层发育,补给源位于向斜西翼沙河上游朝阳寨一带地表沙河水,沿灰岩夹层管道径流,于易罗池排泄,具一定的承压性,为典型埋藏型岩溶。通过分析保山隧道区与岩溶水间的水力关系,认为保山隧道揭示岩溶管道水可能性较小,隧道施

  7. Initiation and Development Processes of Tunnel Systems in the Hilly Loess Region of Northern China

    Institute of Scientific and Technical Information of China (English)

    T.X.ZHU

    2006-01-01

    Tunnel systems in the hilly loess region of northern China are among the largest and most complicated in the world. Tunnel formation and development processes were investigated in the Yangdaogou catchment over the period of 1989 through 2002. Newly formed tunnels on the roads in the Wangjiagou watershed were also examined in detail during a single storm in 2002. Soil samples were taken from various locations of the tunnel systems in the Yangdaogou catchment for chemical and physical analyses.The controlling factors of tunnel formation are surface drainage conditions and soil materials. Rapid downward mechanical erosion by storm flows seems to be responsible for the original formation of inlets. All tunnels are found in loess and none was found in red Tertiary earth. Underground tunnel paths often develop right above an impeding layer, mainly resulting from mechanical erosion rather than chemical dissolution.New inlets develop in old tunnel systems in two major ways. One is roof collapses of an existing tunnel path and the other is the mechanical scouring action of storm flows. A tunnel system can expand upslope or downslope but the associated processes differ. Upslope expansion often starts with the formation of one or more inlets resulting from surface washes, followed by the development of an underground tunnel path. Downslope development of a tunnel system is characterized by uneven enlargement of tunnel paths. This study suggests that the key to control of tunnel development is reducing surface water entering a tunnel.

  8. Tunnel production enhances quality in organic carrot seed production

    DEFF Research Database (Denmark)

    Deleuran, L C; Boelt, B

    2009-01-01

    water supply and thereby introduce drought at proven optimum times, restrict geneflow through insect- and pollen-proof netting, raise the temperature to prolong the growing season and hence the crop duration, and reduce pest attack by preventing pest entrance to the tunnel. In an experiment, tunnel......In Denmark, organic vegetable seed production is possible for some of the late-maturing species when the maturing is performed in lightweight tunnels which are also relevant for the isolation of small-scale production. The tunnel system offers several advantages, e.g., it is possible to control...

  9. Hydraulic Model Test and Research for Water Intake and Energy Dissipation in Tunnel%隧洞进水口及洞内消能水工模型试验研究

    Institute of Scientific and Technical Information of China (English)

    梁文龙; 李贵平; 余跃

    2001-01-01

    针对实际工程中的发电引水隧洞运行的各种工况进行了水工模型试验研究,指明要获得良好的水流流态,过水建筑物各部位结构轮廓的造型应适应水流流线的收缩、流速及压强的变化;为使引水隧洞在各级引水流量下能安全可靠地运行,需慎重确定洞内消能工的体形和尺寸。%Through a series of hydraulic model tests for researching actual power tunnel operation,a conclusion is reached that in order to get a better flow pattern the profile of the wate-carrying structure should be adapted to the variation of water streamline shrinkage,flow velocity and pressure intensity.The configuration and dimension of the kinetic energy dissipator should be selected carefully to make the water tunnel safe and reliable at different levels of diversion dischage.

  10. Tunnel fire dynamics

    CERN Document Server

    Ingason, Haukur; Lönnermark, Anders

    2015-01-01

    This book covers a wide range of issues in fire safety engineering in tunnels, describes the phenomena related to tunnel fire dynamics, presents state-of-the-art research, and gives detailed solutions to these major issues. Examples for calculations are provided. The aim is to significantly improve the understanding of fire safety engineering in tunnels. Chapters on fuel and ventilation control, combustion products, gas temperatures, heat fluxes, smoke stratification, visibility, tenability, design fire curves, heat release, fire suppression and detection, CFD modeling, and scaling techniques all equip readers to create their own fire safety plans for tunnels. This book should be purchased by any engineer or public official with responsibility for tunnels. It would also be of interest to many fire protection engineers as an application of evolving technical principles of fire safety.

  11. Radiometric dating of the Siloam Tunnel, Jerusalem.

    Science.gov (United States)

    Frumkin, Amos; Shimron, Aryeh; Rosenbaum, Jeff

    2003-09-11

    The historical credibility of texts from the Bible is often debated when compared with Iron Age archaeological finds (refs. 1, 2 and references therein). Modern scientific methods may, in principle, be used to independently date structures that seem to be mentioned in the biblical text, to evaluate its historical authenticity. In reality, however, this approach is extremely difficult because of poor archaeological preservation, uncertainty in identification, scarcity of datable materials, and restricted scientific access into well-identified worship sites. Because of these problems, no well-identified Biblical structure has been radiometrically dated until now. Here we report radiocarbon and U-Th dating of the Siloam Tunnel, proving its Iron Age II date; we conclude that the Biblical text presents an accurate historic record of the Siloam Tunnel's construction. Being one of the longest ancient water tunnels lacking intermediate shafts, dating the Siloam Tunnel is a key to determining where and when this technological breakthrough took place. Siloam Tunnel dating also refutes a claim that the tunnel was constructed in the second century bc.

  12. 海底隧道涌水量数值计算的渗透系数确定方法%Study of determining permeability coefficient in water inrush numerical calculation of subsea tunnel

    Institute of Scientific and Technical Information of China (English)

    李术才; 赵岩; 徐帮树; 李利平; 刘钦; 王育奎

    2012-01-01

    海底隧道的建设往往伴随着高风险,而水害则是海底隧道建设期间风险最主要的来源之一,隧道涌水对施工安全与建成后的运营成本控制有着重要影响,因此,对海底隧道进行涌水量预测便显得尤为重要.数值计算方法是当前涌水量预测中应用最广的方法之一,而计算涌水量过程中最关键的问题之一是渗透系数的确定.以青岛胶州湾海底隧道工程为背景,通过数值计算、模型试验与现场监测数据分析等手段相结合的方法,对海底隧道建设期涌水量的预测进行了研究.首先进行海底隧道开挖后涌水量现场监测,得到开挖后涌水量变化曲线;再采用数值计算方法对围岩渗透系数的取值进行反分析,对渗透系数进行不断修正,并在数值计算中成功拟合实测涌水量曲线,所得到的渗透系数即为数值计算中应采用的合理渗透系数.在结合试验段地质情况的基础上将合理渗透系数与前期地勘压水试验得到的渗透系数进行比对,得到两者之间的关系.并通过模型试验的手段对以上结论进行验证.将其应用到海底隧道的涌水量预测中,通过正演数值计算预测围岩相似洞段的涌水量,其结果对海底隧道涌水量预测有一定的参考意义.%The construction of subsea tunnel is high risky and water inrush is one of the main risk sources. If water inrush into the tunnel, it will have an important influence on the safety of construction as well as the control of operation cost after the subsea tunnel is completed. So making water inrush forecast is very important in the construction phase. Numerical analysis is the most popular method used in the prediction of water inrush at present, of which ascertaining the permeability coefficient is one key problem. Taking Qingdao Jiaozhouwan Subsea Tunnel as the project background, this paper deals with water inrush forecast during the subsea tunnel construction period by

  13. Ultrafast scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Botkin, D.A. [California Univ., Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley Lab., CA (United States)

    1995-09-01

    I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM`s atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.

  14. 隧道衬砌渗漏水红外辐射特征影响因素试验研究%EXPERIMENTAL STUDY OF FACTORS AFFECTING THERMAL INFRARED RADIATION CHARACTERISTICS OF TUNNEL LINING WATER LEAKAGE

    Institute of Scientific and Technical Information of China (English)

    豆海涛; 黄宏伟; 薛亚东

    2011-01-01

    In light of infrared thermal imaging of tunnel leakage detection. The factors such as temperature and flow of water leakage, water leakage location, materials of lining surface and so on. Affecting thermal infrared radiation of water leakage are summarized. The concrete specimen is used to simulate water leakage of tunnel lining. The infrared radiation characteristics are recorded and analyzed using infrared thermal imager; and the influencing law is studied. The experimental results are as follows: Thermal image presents temperature of water leakage decreasing along water flow direction, while temperature along water flow cross-section showing parabolic distribution. With the increasing water leakage flow and temperature difference, decreasing angle between horizontal surface and leakage surface, decreasing emissivity of leakage surface and temperature of leakage points increasing linearly, the temperature gradient along water flow direction increases linearly, but the temperature gradient along water flow cross-section decreases. In addition, as for the infrared radiation characteristics with different surface materials, the emissivity correction indicator is established; and the leakage characteristics of infrared thermal images are extracted with Matlab image processing program. The results show that the shape and size of water leakage after modified agree well with the actual one. The study results can provide basis and means for rapid detection and analysis in tunnel operation using infrared thermal imaging technology.%针对隧道渗漏水红外热成像检测问题,总结渗漏水红外辐射特征的影响因素(渗漏温差、流量、位置以及衬砌表面材料等),采用室内混凝土试块注水模拟各工况下隧道衬砌渗漏水,并利用红外热像仪记录分析渗漏水的红外辐射特征,研究不同因素对渗漏水红外辐射特征的影响规律.试验结果表明:渗漏水热图像呈现水流方向温度递减,水流横断面

  15. Tunnelling Association of Canada. Fourth annual general meeting with technical program. Innovation and opportunity. Preprint volume

    Energy Technology Data Exchange (ETDEWEB)

    1984-01-01

    The following papers were presented: opportunities for Canadians in tunnelling; mining related underground construction - what's new in Canada; development in shotcrete for underground support; control of water in tunnelling; support - who needs it.; developments in extruded tunnel lining systems; recent developments in mechanical excavation; technical advancements in raise boring equipment and application; the world's largest- diameter soil tunnel; the ABC's of the Export Development Corporation.

  16. 富水隧道全风化花岗岩和蚀变大理岩段涌水涌砂加固治理技术%The Control of Sand-gushing and Water-bursting of Water-rich Tunnel Located in Area with Fully Weathered Granite and Alteration Marble

    Institute of Scientific and Technical Information of China (English)

    周运祥

    2015-01-01

    The section DK554+400 ~ +456 of Dongkeling tunnel on Guiyang-Guangzhou railway is located in the area with fully weathered granite and alteration marble. During the construction, sand-gushing and water-bursting often arise, not only increasing the difficulties but also posing long-term security risks. In view of the sand-gushing, water-bursting and other defects during the period of construction of the tunnel, it is effective to control sand-gushing and water-bursting through combination of plugging and drainage i. e. sleeve valve pipe grouting around the tunnel and steel pipe pile grouting at tunnel bottom, and setting-up drainage holes. The successful practices and technical parameters can be referred to similar project.%贵广铁路东科岭隧道DK554+400~+456段处于全风化花岗岩、蚀变大理岩区接触带,隧道施工遭遇了长期的涌水涌砂等病害。结合东科岭隧道施工期间的涌水、涌砂概况及病害成因,治理采用堵排结合,即洞身全风化花岗岩段采用袖阀管注浆、仰拱底部蚀变大理岩部位采用钢管桩注浆加固,同时设置泄水洞等措施,成功解决了涌水涌砂加固治理难题。

  17. Decompression of magma into repository tunnels

    NARCIS (Netherlands)

    Bokhove, Onno; Woods, A.W.

    2002-01-01

    It is nontrivial to find and design safe repository sites for nuclear waste. It appears common sense to drill tunnels as repository sites in a mountain in remote and relatively dry regions. However, erosion of the waste canisters by naturally abundant chemicals in the mountains water cycle remains a

  18. Virtual photons in macroscopic tunneling

    OpenAIRE

    Aichmann, Horst; Nimtz, Guenter; Bruney, Paul

    2015-01-01

    Tunnelling processes are thought to proceed via virtual waves due to observed superluminal (faster than light) signal speeds. Some assume such speeds must violate causality. These assumptions contradict, for instance, superluminally tunnelled music and optical tunnelling couplers applied in fiber communication. Recently tunnelling barriers were conjectured to be cavities, wherein the tunnelled output signal is not causally related with the input. The tests described here resolve that tunnelli...

  19. 超长输水隧洞多种类传感器数据传输方式%Information communication method of multiple sensors for super long distance water delivery tunnel

    Institute of Scientific and Technical Information of China (English)

    范光亚; 何勇军; 李宏恩; 李铮; 郭晓红

    2015-01-01

    为了解决超长输水隧洞安全监测工程数据传输距离远以及因安装不同类型传感器导致监测数据格式多样的问题,在对水利工程安全监测系统常用数据传输方式进行优劣比较的基础上,提出适用于光纤传感器和常规传感器交叉组合监测的GPRS数据传输方式,探讨其在超长输水隧洞工程监测信息传输中的适用性和可行性,并在西南某超长输水隧洞工程中进行应用验证。根据超长输水隧洞工程通常无交流电供电的特点,提出风光电互补供电的方式,能够满足监测系统长期供电需求。%In this study it is introduced the general packet radio service( GPRS) information communication method, which combining fiber sensors and common sensors, for the long transmission distance of safety monitoring engineering data in super long distance water delivery tunnel and different data formats(resulted from multiple sensors). And it is compared with the common information communication methods about safety monitoring system in hydraulic engineering practice. Besides, it is discussed the applicability and feasibility of the information communication method for super long distance water delivery tunnel as well as tested in an engineering practice in the Southwest China. Due to the fact that alternating current is not available for outdoor projects of super long distance water delivery tunnel, it is proposed the power supply mode of solar, wind, and electrical energy, which are able to meet the power supply demand of monitoring system for a long time.

  20. Wind Tunnel Testing Facilities

    Data.gov (United States)

    Federal Laboratory Consortium — NASA Ames Research Center is pleased to offer the services of our premier wind tunnel facilities that have a broad range of proven testing capabilities to customers...

  1. INCAS TRISONIC WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Florin MUNTEANU

    2009-09-01

    Full Text Available The 1.2 m x 1.2 m Trisonic Blowdown Wind Tunnel is the largest of the experimental facilities at the National Institute for Aerospace Research - I.N.C.A.S. "Elie Carafoli", Bucharest, Romania. The tunnel has been designed by the Canadian company DSMA (now AIOLOS and since its commissioning in 1978 has performed high speed aerodynamic tests for more than 120 projects of aircraft, missiles and other objects among which the twin jet fighter IAR-93, the jet trainer IAR-99, the MIG-21 Lancer, the Polish jet fighter YRYDA and others. In the last years the wind tunnel has been used mostly for experimental research in European projects such as UFAST. The high flow quality parameters and the wide range of testing capabilities ensure the competitivity of the tunnel at an international level.

  2. Quantum tunneling with friction

    Science.gov (United States)

    Tokieda, M.; Hagino, K.

    2017-05-01

    Using the phenomenological quantum friction models introduced by P. Caldirola [Nuovo Cimento 18, 393 (1941), 10.1007/BF02960144] and E. Kanai [Prog. Theor. Phys. 3, 440 (1948), 10.1143/ptp/3.4.440], M. D. Kostin [J. Chem. Phys. 57, 3589 (1972), 10.1063/1.1678812], and K. Albrecht [Phys. Lett. B 56, 127 (1975), 10.1016/0370-2693(75)90283-X], we study quantum tunneling of a one-dimensional potential in the presence of energy dissipation. To this end, we calculate the tunneling probability using a time-dependent wave-packet method. The friction reduces the tunneling probability. We show that the three models provide similar penetrabilities to each other, among which the Caldirola-Kanai model requires the least numerical effort. We also discuss the effect of energy dissipation on quantum tunneling in terms of barrier distributions.

  3. Wind Tunnel Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This ARDEC facility consists of subsonic, transonic, and supersonic wind tunnels to acquire aerodynamic data. Full-scale and sub-scale models of munitions are fitted...

  4. Structural Safety Assessment of Existing Multiarch Tunnel: A Case Study

    Directory of Open Access Journals (Sweden)

    Jinxing Lai

    2017-01-01

    Full Text Available Structural health assessment is one of the key activities in maintaining the performance of a tunnel during its service life. Due to the development of modern detection technology, comprehensive structural health assessment system is being established for operating tunnels. To evaluate the actual operational state of Shitigou tunnel, overall detection of the liner crack, tunnel seepage, and liner void was conducted by employing the modern detection technology, such as crack width monitoring technology, concrete strength monitoring technology, and electromagnetic wave nondestructive monitoring technology. Through the statistical analysis of the detection results, the distribution characteristic, development law, and damage grade of structural defects were obtained. Tunnel liner cracks are mainly located on the middle wall; serious water leakage is encountered on the side wall, middle wall, and vault; the strength of foundation and liner structure of left tunnel does not meet the design requirement; the liner voids are mostly located at the tunnel entrance section, especially, on the tunnel vault; and the proportion of influence factors of structural defects should be considered. The research results presented for this study can serve as references for effective design and health assessment of existing multiarch tunnel projects.

  5. A study for the KAERI research tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.; Hwang, Y. S.; Park, H. S.; Park, S. K.; Park, B. Y.; Bang, K. S.; Kuh, J. H.; Kang, K. H

    1997-12-01

    Major goal of the R and D on the KAERI Research Tunnel in 1997 are 1) concept development of the KAERI research tunnel and its major units 2) computer simulation of facilities 3) study on thermo-hydro mechanical coupling in the vicinity of a waste repository 4) effect of excavated distrubed zone. In addition supplementary site investigation to understand the distribution of stresses in the site was done along with long term monitoring of the water table. (author). 44 refs., 16 tabs., 36 figs

  6. Chloride Transport in Undersea Concrete Tunnel

    Directory of Open Access Journals (Sweden)

    Yuanzhu Zhang

    2016-01-01

    Full Text Available Based on water penetration in unsaturated concrete of underwater tunnel, a diffusion-advection theoretical model of chloride in undersea concrete tunnel was proposed. The basic parameters including porosity, saturated hydraulic conductivity, chloride diffusion coefficient, initial water saturation, and moisture retention function of concrete specimens with two water-binder ratios were determined through lab-scale experiments. The variation of chloride concentration with pressuring time, location, solution concentration, initial saturation, hydraulic pressure, and water-binder ratio was investigated through chloride transport tests under external water pressure. In addition, the change and distribution of chloride concentration of isothermal horizontal flow were numerically analyzed using TOUGH2 software. The results show that chloride transport in unsaturated concrete under external water pressure is a combined effect of diffusion and advection instead of diffusion. Chloride concentration increased with increasing solution concentration for diffusion and increased with an increase in water pressure and a decrease in initial saturation for advection. The dominant driving force converted with time and saturation. When predicting the service life of undersea concrete tunnel, it is suggested that advection is taken into consideration; otherwise the durability tends to be unsafe.

  7. Gravity Tunnel Drag

    CERN Document Server

    Concannon, Thomas

    2016-01-01

    The time it takes to fall down a tunnel through the center of the Earth to the other side takes approximately 42 minutes, but only when given several simplifying assumptions: a uniform density Earth; a gravitational field that varies linearly with radial position; a non-rotating Earth; a tunnel evacuated of air; and zero friction along the sides of the tunnel. Though several papers have singularly relaxed the first three assumptions, in this paper we relax the final two assumptions and analyze the motion of a body experiencing these types of drag forces in the tunnel. Under such drag forces, we calculate the motion of a transport vehicle through a tunnel of the Earth under uniform density, under constant gravitational acceleration, and finally under the more realistic Preliminary Reference Earth Model (PREM) density data. We find the density profile corresponding to a constant gravitational acceleration better models the motion through the tunnel compared to the PREM density profile, and the uniform density m...

  8. 淮南市中央公园下穿隧道抗浮地下水位分析%On analysis of anti-floating underground water level at undercrossing tunnel of central park in Huainan

    Institute of Scientific and Technical Information of China (English)

    赵华宏; 沈洪波; 李昊煜

    2012-01-01

    根据淮南市山南新区南纬六路下穿隧道抗浮地下水位工程的实际情况,从场区地形地貌、地表水系规划、水文地质条件、地下水位控制要素等方面进行了分析,合理确定设计抗浮地下水位,以期从最大程度上满足工程建设的安全运营。%According to the fact of the anti-floating underground water level project at Nanwei 6th road of Shannan new district of Huainan, the paper analyzes from the topography and geomorphology, the planning for the surface water system, the hydrological conditions, and the controlling elements of the underground water level by taking the undercrossing central park tunnel as the example, and has the reasonable identification for the design of the anti-floating underground water level, so as to meet the demands of the safe operation of the construction maximally.

  9. Aespoe Hard Rock Laboratory. The TASS-tunnel. Geological mapping

    Energy Technology Data Exchange (ETDEWEB)

    Hardenby, Carljohan (Vattenfall Power Consultant AB (Sweden)); Sigurdsson, Oskar (HAskGeokonsult AB (Sweden))

    2010-12-15

    The project entitled 'Sealing of tunnel at great depth' (Fintaetning av tunnel paa stort djup) needed a new tunnel in an area as undisturbed as possible and with cross-cutting water-bearing structures. The new tunnel, which was given the name TASS, was excavated on the -450 m level of SKB's Aespoe Hard Rock Laboratory (Aespoe HRL). The length of the tunnel is approximately 80 m and the theoretical tunnel area 19 m2. As is the case with all the other tunnels of the Aespoe HRL, the new tunnel has been geologically mapped. In addition, laser scanning combined with digital photography has been carried out. The tunnel was also used to test various types of explosives, borehole layouts and drilling techniques. The geological mapping of tunnel floor, walls and roof took place on four major occasions when a halt was made in tunnel excavation to allow for various tests. Before the mapping started on these occasions, laser scanning took place. The tunnel faces were mapped after each round (drilling, blasting and unloading). The present report describes the geological features of the tunnel and briefly how the laser scanning was performed. Water-bearing structures have been compared to similar structures in the neighbouring tunnels. The rock type names used here follow the old established Aespoe HRL nomenclature. Narrow (<0.1 m wide) dykes are normally mapped as fracture fillings. The dominating rock type is Aespoe diorite, which constitutes some 90 % of the rock mass. It is mostly mapped as fresh rock. . Minor constituents of the rock mass are fine-grained granite, hybrid rock, pegmatite, quartz veins/lenses and undifferentiated mafic rock. The mapping of fractures and deformation zones considers a number of parameters such as number of fractures, open/healed, width, length, description of fracture surfaces (roughness, planarity, etc), fracture filling, alteration and water. The deformation zones are discriminated into two main categories (&apos

  10. Suppression of tunneling rate fluctuations in tunnel field-effect transistors by enhancing tunneling probability

    Science.gov (United States)

    Mori, Takahiro; Migita, Shinji; Fukuda, Koichi; Asai, Hidehiro; Morita, Yukinori; Mizubayashi, Wataru; Liu, Yongxun; O’uchi, Shin-ichi; Fuketa, Hiroshi; Otsuka, Shintaro; Yasuda, Tetsuji; Masahara, Meishoku; Ota, Hiroyuki; Matsukawa, Takashi

    2017-04-01

    This paper discusses the impact of the tunneling probability on the variability of tunnel field-effect transistors (TFETs). Isoelectronic trap (IET) technology, which enhances the tunneling current in TFETs, is used to suppress the variability of the ON current and threshold voltage. The simulation results show that suppressing the tunneling rate fluctuations results in suppression of the variability. In addition, a formula describing the relationship between the tunneling rate fluctuations and the electric field strength is derived based on Kane’s band-to-band tunneling model. This formula indicates that the magnitude of the tunneling rate fluctuations is proportional to the magnitude of the fluctuations in the electric field strength and a higher tunneling probability results in a lower variability. The derived relationship is universally valid for any technologies that exploit enhancement of the tunneling probability, including IET technology, channel material engineering, heterojunctions, strain engineering, etc.

  11. Monitoring in Building Road Tunnel Across Coal Measures

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In some cases coal measures,goaf,big caves,and huge faults,as well as high initial stress cannot be avoided in road tunnel excavation.These geological features may make it more difficul practical tunnel construction. So it is necessary to take strong precautious measures against gas outburst,water bursting and roof fall in a tunnel across coal measures with risk of gas outburst.The techniques,such as advance drilling exploration,multiple-cycle shallow depth hole controlled blasting,reinforced supporting,which include concrete grouting and twice supporting,and monitoring measures are often applied in the construction of tunnels and satisfied results are achieved. Results in this paper can help others to get experiences in road tunnel construction with similar geological features.

  12. EXPERIMENTAL INVESTIGATION OF EMERGENCY GATE SHUTTING FOR ORIFICE TUNNEL

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In the process of the emergence gate shutting of one orifice tunnel, a big noise and great vibration may be observed in the mid gate chamber. In order to guarantee the working safety of orifice tunnels, an experimental investiga-tion is carried out in Sichuan University. In the investigation,the fluctuation pressure along the tunnel and the wind velocity in the entry of emergency gate are measured. In the mean time, the fluid state in orifice tunnel is carefully observed and analyzed. The reasons of the noise and vibration in the mid gate chamber are found out and some countermeasures are presented in this paper. The conclusions are useful to the ori-fice tunnels with high water head and huge discharge.

  13. Boiling visualization on vertical fins with tunnel-pore structures

    Directory of Open Access Journals (Sweden)

    Kaniowski Robert

    2012-04-01

    Full Text Available The paper presents experimental studies of nucleate boiling heat transfer from a system of connected horizontal and vertical subsurface tunnels. The experiments were carried out for water at atmospheric pressure. The tunnel external covers were manufactured out of perforated copper foil (holes diameter 0.3 mm, sintered with the mini-fins, formed on the vertical side of the 10 mm high rectangular fins and horizontal inter-fin surface. The image acquisition speed was 493 fps (at resolution 400 × 300 pixels with Photonfocus PHOT MV-D1024-160-CL camera. Visualization investigations aimed to identify nucleation sites and flow patterns and to determine the bubble departure diameter and frequency at various superheats for vertical tunnels. At low superheat vapor bubbles are generated nearly exclusively by the vertical tunnel. At medium values of superheat, pores of the horizontal tunnel activate.

  14. An Analytical Method for Groundwater Inflow into a Drained Circular Tunnel.

    Science.gov (United States)

    Su, Kai; Zhou, Yafeng; Wu, Hegao; Shi, Changzheng; Zhou, Li

    2017-09-01

    Groundwater inflow estimation is essential for the design and construction of tunnel and the assessment of the environmental impacts. Analytical solutions used in current engineering practice do not adequately account for the effect of the excavation-induced drawdown, which leads to significant change in pore water pressure distribution and reductions of the water level beyond tunnel. Based on the numerical analysis results, this article proposes semianalytical method to predict the height of lowered water level and groundwater tunnel inflow. The tunnel problem is conceptualized as two-dimensional flow in a plane perpendicular to the tunnel axis. The analytical formula, considering the effect of the excavation-induced drawdown, provides a better prediction of the tunnel inflow compared to the existing analytical formulas, even for the cases with inclined groundwater level. © 2017, National Ground Water Association.

  15. Effects of tunneling on groundwater flow and swelling of clay-sulfate rocks

    Science.gov (United States)

    Butscher, Christoph; Einstein, Herbert H.; Huggenberger, Peter

    2011-11-01

    Swelling of clay-sulfate rocks is a major threat in tunneling. It is triggered by the transformation of the sulfate mineral anhydrite into gypsum as a result of water inflow in anhydrite-containing layers after tunnel excavation. The present study investigates the hydraulic effects of tunneling on groundwater flow and analyzes how hydraulic changes caused by excavation lead to water inflow into anhydrite-containing layers in the tunnel area. Numerical groundwater models are used to conduct scenario simulations that allow one to relate hydrogeological conditions to rock swelling. The influence of the topographic setting, the excavation-damaged zone around the tunnel, the sealing effect of the tunnel liner, and the geological configuration are analyzed separately. The analysis is performed for synthetic situations and is complemented by a case study from a tunnel in Switzerland. The results illustrate the importance of geological and hydraulic information when assessing the risk of swelling at an actual site.

  16. Early times in tunneling

    CERN Document Server

    García-Calderón, G; Garcia-Calderon, Gaston; Villavicencio, Jorge

    2000-01-01

    Exact analytical solutions of the time-dependent Schr\\"odinger equation with the initial condition of an incident cutoff wave are used to investigate the traversal time for tunneling. The probability density starts from a vanishing value along the tunneling and transmitted regions of the potential. At the barrier width it exhibits, at early times, a distribution of traversal times that typically has a peak $\\tau_p$ and a width $\\Delta \\tau$. Numerical results for other tunneling times, as the phase-delay time, fall within $\\Delta \\tau$. The B\\"uttiker traversal time is the closest to $\\tau_p$. Our results resemble calculations based on Feynman paths if its noisy behaviour is ignored.

  17. Tunneling Through Black Rings

    Institute of Scientific and Technical Information of China (English)

    ZHAO Liu

    2007-01-01

    Hawking radiation of black ring solutions to 5-dimensional Einstein-Maxwell-dilaton theory is analyzed by use of the Parikh-Wilczek tunneling method. To get the correct tunneling amplitude and emission rate, we adopt and develop the Angheben-Nadalini-Vanzo-Zerbini covariant approach to cover the effects of rotation and electronic discharge all at once, and the effect of back reaction is also taken into account. This constitutes a unified approach to the tunneling problem. Provided the first law of thermodynamics for black rings holds, the emission rate is proportional to the exponential of the change of Bekenstein-Hawking entropy. Explicit calculation for black ring temperatures agrees exactly with the results obtained via the classical surface gravity method and the quasi-local formalism.

  18. Femtosecond scanning tunneling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, A.J.; Donati, G.P.; Rodriguez, G.; Gosnell, T.R.; Trugman, S.A.; Some, D.I.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). By combining scanning tunneling microscopy with ultrafast optical techniques we have developed a novel tool to probe phenomena on atomic time and length scales. We have built and characterized an ultrafast scanning tunneling microscope in terms of temporal resolution, sensitivity and dynamic range. Using a novel photoconductive low-temperature-grown GaAs tip, we have achieved a temporal resolution of 1.5 picoseconds and a spatial resolution of 10 nanometers. This scanning tunneling microscope has both cryogenic and ultra-high vacuum capabilities, enabling the study of a wide range of important scientific problems.

  19. Comprehensive surface geophysical investigation of karst caves ahead of the tunnel face: A case study in the Xiaoheyan section of the water supply project from Songhua River, Jilin, China

    Science.gov (United States)

    Bin, Liu; Zhengyu, Liu; Shucai, Li; Lichao, Nie; Maoxin, Su; Huaifeng, Sun; Kerui, Fan; Xinxin, Zhang; Yonghao, Pang

    2017-09-01

    This paper describes the application of a comprehensive surface geophysical investigation of underground karst systems ahead of the tunnel face in the Xiaoheyan section in the main line of the water supply project from Songhua River, located in Jilin, China. To make an accurate investigation, Surface Electrical Resistivity Tomography (S-ERT), Transient Electromagnetic Method (TEM), Geological Drilling (Geo-D) and Three-dimensional Cross-hole Electrical Resistivity Tomography (3D cross-hole ERT) were applied to gain a comprehensive interpretation. To begin with, S-ERT and TEM are adopted to detect and delineate the underground karst zone. Based on the detection results, surface and in-tunnel Geo-D are placed in major areas with more specific and accurate information gained. After that, survey lines of 3D cross-hole ERT are used to conduct detailed exploration towards underground karst system. In the comprehensive investigation, it is the major question to make the best of prior information so as to promote the quality of detection. The paper has put forward strategies to make the full use of effective information in data processing and the main ideas of those strategies include: (1) Take the resistivity distribution of the subsurface stratum gained by S-ERT inversion as the initial model of TEM inversion; (2) Arrange borehole positions with the results of S-ERT and TEM. After that, gain more accurate information about resistivity of subsurface stratum using those boreholes located; (3) Through the comprehensive analysis of the information about S-ERT, TEM and Geo-D, set the initial model of 3D cross-hole resistivity inversion and meanwhile, gain the variation range of stratum resistivity. At last, a 3D cross-hole resistivity inversion based on the incorporated initial model and inequality constraint is conducted. Constrained inversion and joint interpretation are realized by the effective use of prior information in comprehensive investigation, helping to suppress

  20. 大坡度引水隧道无轨运输出渣方式的应用%On the Application of the Trackless Transportation Mode to the Slug-Cleanout Construction for Great-Gradient Water Diversion Tunnels

    Institute of Scientific and Technical Information of China (English)

    白福庆

    2014-01-01

    辽西北供水工程11#支洞,断面小、坡度大,出渣运输方式是决定工期的关键控制因素。采用无轨运输出渣方式,存在以下问题:隧道纵坡坡度较大,运输渣车爬坡困难、存在严重的安全隐患;断面小,自卸车在陡坡上运行和洞内调头困难等。对此采取扩大隧道开挖断面、设置避车洞,改装车辆、确保车辆制动的可靠性;加强安全管理措施等。实践证明,采用无轨运输方式出渣具有节约工期、经济效益显著等特点,可根据实际工况加以选用。%Owing to the 1 1 th branch tunnel of the water supply proj ect in the northwest of Liaoning province being small in cross-section and great in gradient,the slug-cleanout and transport mode becomes the key control factor for the determination of the construction duration of the proj ect.If the trackless slug-cleanout and transport mode were adopted,the following problems would have to be faced:as the longitudinal gradient of the tunnel is comparatively great,it would be very hard for slug-trans-porting trucks to go up the steep slope,which might result in very serious accidents in safety;as the cross-section is very small,it would be very difficult for tip trucks to run on the steep slope and turn about inside the narrow tunnel.To solve these problems,the cross-section of the face being excavated is enlarged,turn-out caves are provided,tip trucks are transformed to en-sure the reliability of their brakes;safety managing measures are strengthened.Practice shows that the use of the trackless slug-cleanout and transport mode has the advantages of shortening the construction duration,achieving very obvious economic bene-fit,etc.Therefore,the mode may be applied to the construction of certain proj ects according to the specific construction condi-tions.

  1. 含水疏松砂岩隧洞冻结施工三维数值模拟%3-D numerical simulation of frozen construction for tunnel of water content loose sandstone

    Institute of Scientific and Technical Information of China (English)

    任伯锋; 许健; 赵琨

    2014-01-01

    By using artificially ground freezing process,No.7 tunnel export of Gansu YinTao Proj ect Phase-I successfully pass through water bearing loose sandstones formations.On the basis of three-dimen-sional numerical simulation for work progress through the application of the large finite element analysis software ANSYS,this paper analyzed the displacement and stress distributions of frozen soil curtain in the process of tunnel excavation,and put forward in the construction process of some security measures,in or-der to accurately grasp the changes and development of frozen soil thickness of soil temperature,as well as determine the optimal excavation.The analysis results and engineering practice showed that the maximum tension,compression,shear stress calculation values were 3.02,0.15 and 0.97 Mpa,the safety coefficient was 13,1.9 and 1.5 respectively,and its extremum position was determined.It also showed that using freezing method through the water tunnel was reasonable in loose sandstone reservoir.In this paper,some effective measures and reasonable advice were put forward for freezing construction by integrating on-site data monitoring,which provided theoretical support for the freezing construction of No.7 tunnel export of Gansu YinTao Proj ect Phase-I,and set up a reference for similar proj ects meanwhile.%甘肃省引洮供水一期工程总干渠7#引水隧洞出口,采用冻结施工法成功穿越了含水疏松砂岩地层.应用大型有限元软件 ANSYS,对冻结施工过程进行了三维数值模拟,分析了隧洞开挖过程中冻土帷幕的位移和应力分布情况,并提出了在施工过程中的一些安全保障措施,以便准确地掌握冻土温度的变化及冻土帷幕厚度发展状况,从而确定最优的开挖时间.分析结果及工程实践表明:最大拉、压、剪应力计算值分别为3.02、0.15和0.97 Mpa,计算值相对于设计值的安全系数分别为13、1.9 和 1.5,并确定了其极值发生位置.同时也表明

  2. Numerical analysis of tunnel liner failure mechanism in expansive soil considering water-increased state%增湿条件下膨胀土隧道衬砌破坏数值分析

    Institute of Scientific and Technical Information of China (English)

    曾仲毅; 徐帮树; 胡世权; 陈诚

    2014-01-01

    针对小河沟膨胀土隧道降雨增湿塌方现象,以围岩含水率分布变化引起膨胀应力场为主要研究内容,展开增湿对隧道支护结构的影响研究。首先,利用热传导热能量平衡方程与孔隙渗流连续方程数学描述相似性,推导出热传导膨胀模拟增湿膨胀的替代方程。然后,结合室内试验和文献资料,率定膨胀土膨胀力及渗流参数。最后,在正确考虑地质构造影响的基础上运用有限差分软件 FLAC3D热-力耦合模块进行建模计算,分别对不同膨胀力模型的增湿过程进行仿真模拟,得出支护结构受力变形随含水率分布及膨胀力大小的变化规律。分析得到了对隧道支护结构造成不良影响的关键含水率和膨胀力值。研究成果可以有效指导膨胀性黄土隧道支护设计和变形控制。%In light of the collapse of an expansive soil tunnel owing to rainfall infiltration, swelling stress field caused by the change in the moisture content distribution of surrounding soil was taken into consideration to solve the problem. At first, due to the similarity of continuum heat conduction energy-balance equation and seepage continuity equation, an alternative expansive equation is derived based on the theory of heat conduction expansive to simulate water-increased expansion of expansive soil, and then determine the swelling force and seepage parameters by laboratory test and engineering simulation. Finally, considering the proper geologic factors, a numerical model of tunnel is established by means of thermal-mechanical coupling of FLAC3D. And by the simulations of tunnel with different swelling forces under water-increased state, relation curves are acquired between liner deformation and moisture content, swelling force. According to the above analysis, turning points of moisture content and swelling force to prevent liner from failure are proposed, which can effectively guide the design and

  3. Tunneling in Axion Monodromy

    CERN Document Server

    Brown, Jon; Shiu, Gary; Soler, Pablo

    2016-01-01

    The Coleman formula for vacuum decay and bubble nucleation has been used to estimate the tunneling rate in models of axion monodromy in recent literature. However, several of Coleman's original assumptions do not hold for such models. Here we derive a new estimate with this in mind using a similar Euclidean procedure. We find that there are significant regions of parameter space for which the tunneling rate in axion monodromy is not well approximated by the Coleman formula. However, there is also a regime relevant to large field inflation in which both estimates parametrically agree. We also briefly comment on the applications of our results to the relaxion scenario.

  4. Tunneling in axion monodromy

    Science.gov (United States)

    Brown, Jon; Cottrell, William; Shiu, Gary; Soler, Pablo

    2016-10-01

    The Coleman formula for vacuum decay and bubble nucleation has been used to estimate the tunneling rate in models of axion monodromy in recent literature. However, several of Coleman's original assumptions do not hold for such models. Here we derive a new estimate with this in mind using a similar Euclidean procedure. We find that there are significant regions of parameter space for which the tunneling rate in axion monodromy is not well approximated by the Coleman formula. However, there is also a regime relevant to large field inflation in which both estimates parametrically agree. We also briefly comment on the applications of our results to the relaxion scenario.

  5. Long distance tunneling

    CERN Document Server

    Ivlev, B I

    2005-01-01

    Quantum tunneling between two potential wells in a magnetic field can be strongly increased when the potential barrier varies in the direction perpendicular to the line connecting the two wells and remains constant along this line. A periodic structure of the wave function is formed in the direction joining the wells. The resulting motion can be coherent like motion in a conventional narrow band periodic structure. A particle penetrates the barrier over a long distance which strongly contrasts to WKB-like tunneling. The whole problem is stationary. The coherent process can be influenced by dissipation.

  6. Breaking through the tranfer tunnel

    CERN Multimedia

    Laurent Guiraud

    2001-01-01

    This image shows the tunnel boring machine breaking through the transfer tunnel into the LHC tunnel. Proton beams will be transferred from the SPS pre-accelerator to the LHC at 450 GeV through two specially constructed transfer tunnels. From left to right: LHC Project Director, Lyn Evans; CERN Director-General (at the time), Luciano Maiani, and Director for Accelerators, Kurt Hubner.

  7. 蛋形断面无压隧洞水面线解析算法%Analytical algorithm for water surface profile of free-flow tunnel with egg-shaped cross-section

    Institute of Scientific and Technical Information of China (English)

    滕凯

    2014-01-01

    针对蛋形断面形式复杂,用常规方法完成水面线计算不但存在误差累积而且计算工作量大、效率低的问题,依据优化拟合理论,以标准剩余差最小为目标函数,在工程适用参数范围内,经拟合计算得到了一个简化通用算式来替代原积分中的分段且不可积函数,并推求出了蛋形断面隧洞水面线计算的近似解析通式。拟合误差分析和实例计算结果表明:解析通式的计算误差小于2%;利用近似解析通式完成蛋形断面隧洞水面线计算可使求解过程大幅度简化,工作效率明显提高。%Egg-shaped cross-sections are complex in form,calculating such water surface profiles with conventional methods has the disadvantages of error accumulation, a large amount of necessary calculation, and low efficiency. To improve the calculation, the optimum matching theory was adopted in this study. An objective function of minimized standard residual deviation was selected, and a simplified general formula was obtained by the fitting calculation, which could be used to substitute for the segmented and non-integrable function in the original integral within the parameter range applicable to projects. Finally, a simplified formula was deduced for calculation of water surface profiles of tunnels with egg-shaped cross-sections. Error analysis and case study show that the calculation error of this calculation is less than 2%. The approximate formula greatly simplifies the water surface profile calculation of tunnels with egg-shaped cross-sections, and the working efficiency is obviously improved.

  8. Tunnelling with wormhole creation

    Energy Technology Data Exchange (ETDEWEB)

    Ansoldi, S. [National Institute of Nuclear Physics (INFN) (Italy); Tanaka, T., E-mail: tanaka@yukawa.kyoto-u.ac.jp [Kyoto University, Department of Physics (Japan)

    2015-03-15

    The description of quantum tunnelling in the presence of gravity shows subtleties in some cases. We discuss wormhole production in the context of the spherically symmetric thin-shell approximation. By presenting a fully consistent treatment based on canonical quantization, we solve a controversy present in the literature.

  9. INCAS SUBSONIC WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Corneliu STOICA

    2009-09-01

    Full Text Available The INCAS Subsonic Wind Tunnel is a closed circuit, continuous, atmospheric pressure facility with a maximum speed of 110 m/s. The test section is octagonal ,of 2.5 m wide, 2.0 m high and 4 m long. The tunnel is powered by a 1200 kW, air cooled variable speed DC motor which drives a 12 blade, 3.5 m diameter fan and is equipped with a six component pyramidal type external mechanical balance with a 700 Kgf maximum lift capacity.The angle of attack range is between -45º and +45º while the yaw angle range is between -140º and +216º .The data acquisition system has been modified recently to allow the recording of all test data on a PC - type computer using LABVIEW and a PXI – type chassis containing specialized data acquisition modules.The tunnel is equipped with a variable frequency electrical supply system for powered models and a 10 bar compressed air supply for pneumatic flow control applications.In the recent years the subsonic wind tunnel has been intensively used for tests within several European projects (AVERT, CESAR and others.

  10. 中天山隧道大埋深高水压节理密集带涌水处理%Countermeasures against Water Gushing of Zhongtianshan Tunnel at Deep-buried and High Water-pressured and Dense-jointed Area

    Institute of Scientific and Technical Information of China (English)

    朵生君

    2013-01-01

    南疆吐库二线中天山隧道施工中突然发生涌水,水压高达6.3MPa,首先采用超前地质预报、水压、水量观测及连通试验对工程、水文地质特征进行分析,在此基础上结合涌水处理方案研究、现场试验结果,提出了“分区定位、注浆减排、泄水降压、合理步距”的处理原则,成功通过了高压富水段,保证了施工安全.%Water gushed out suddenly when the Zhongtianshan Tunnel on Turpan-Korla Line 2 of Southern Xinjiang Railway was being constructed,with the water pressure as high as 6.3Mpa.Because of this,the geology and the hydrogeology characteristics were analyzed by means of geological forecast,and water amount observing method and hydraulic connectivity test.And then,by combining the scheme research result with field test result,the countermeasure principle against the water gushing was put forward as below:position confirmation by regionalizing,outflow reduction by grouting,pressure reduction by water releasing,and support interval by reasonable layout.As a result,this countermeasure principle has enabled the tunnel to pass through the high-pressured and water-rich area successfully,ensuring the safety of construction.

  11. Classical trajectories and quantum tunneling

    CERN Document Server

    Ivlev, B I

    2003-01-01

    The problem of inter-band tunneling in a semiconductor (Zener breakdown) in a nonstationary and homogeneous electric field is solved exactly. Using the exact analytical solution, the approximation based on classical trajectories is studied. A new mechanism of enhanced tunneling through static non-one-dimensional barriers is proposed in addition to well known normal tunneling solely described by a trajectory in imaginary time. Under certain conditions on the barrier shape and the particle energy, the probability of enhanced tunneling is not exponentially small even for non-transparent barriers, in contrast to the case of normal tunneling.

  12. SIMULATION OF TURBULENT FLOW THROUGH TARBELA DAM TUNNEL 3

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2010-11-01

    Full Text Available Tarbela dam is one of the largest earth filled dam in the world. The sediments inflow in the Tarbela reservoir has resulted in reduction in water storage capacity. During the recent years, a reasonable increase of sediment particles in the tunnel is observed. This is damaging tunnels, power generating units and is a severe threat to the plant equipment. To the authors knowledge, to-date no comprehensive simulation studies are performed for flooding in the reservoir or turbulent flows in the tunnels. In this paper, turbulent flow using Reynolds Stress Model in Tunnel 3 of the Tarbela Dam is analyzed with and without considering the effect of sediments particle. Results are presented for three different water heads in the reservoir i.e. considering summer, winter and average seasons and for one-way and two-way/full coupling for sediments particle tracking/deposition. The effect of cavitation erosion and damage to the tunnels due to erosion is investigated and results are compared with the experimental erosion results for similar geometries and are found in good agreement. Sediments particulate analysis is also performed for the validation of the samples collected from WAPDA. Moreover, pressure, velocity and erosion rate results are discussed to get complete behavior of the turbulent flow of water in the tunnel.

  13. A draining concept for tunnels with the aim of optimizing their geothermal utilization; Concept de drainage des tunnels en vue d'une optimisation de l'utilisation geothermique (valorisation du potentiel geothermique des tunnels - Recherche d'optimisation)

    Energy Technology Data Exchange (ETDEWEB)

    Wilhelm, J.

    2006-07-01

    Since almost 30 years, the geothermal potential of mountain water has been exploited in Swiss tunnels. The first known application was at the southern mouth of the St. Gotthard road tunnel, where the draining water was collected for heating a waiting-room in Airolo. The present report prepared for the Swiss Federal Office of Energy (SFOE) examines the possibilities for enhancing the efficiency and thus the potential of this geothermal application. They include: a) Reducing thermal losses by thermally insulating the water pipes along the tunnel. b) Increasing the usable quantity of water by providing additional drillings along the tunnel. c) Providing more than one water pipe, thus allowing to collect water of different temperatures in separate pipes. d) New technologies: add heat exchangers to tunnel construction elements in direct contact with the rocks, e.g. rock anchors, liners, concrete elements in the floor. The last chapter examines possible improvements for two large tunnels currently in project.

  14. STUDY OF DISTRIBUTION LAW OF WATER PRESSURE ACTING ON COMPOSITE LINING AND REASONABLE PARAMETERS OF GROUTING CIRCLE FOR SUBSEA TUNNEL%海底隧道复合衬砌水压力分布规律及合理注浆加固圈参数研究

    Institute of Scientific and Technical Information of China (English)

    李鹏飞; 张顶立; 赵勇; 张成平

    2012-01-01

    与普通山岭隧道不同,海底隧道深埋于海床之下,地下水的处理是其修建过程中的关键问题,而隧道渗水量控制及衬砌结构水荷载确定又是地下水处理的核心问题.采用“堵水限排”的设计理念,设计海底隧道复合衬砌结构防排水系统,可以实现以较小的排放量明显折减甚至消除作用在支护结构上的外水压力,使海底隧道衬砌结构设计更经济.基于地下水水力学理论,推导海底隧道渗水量和复合衬砌结构外水压力的计算方法,并结合厦门海底隧道工程实践,采用理论分析和数值模拟方法揭示初期支护、二次衬砌以及注浆加固圈等参数的变化对隧道渗水量和衬砌外水压力的影响规律.在此基础上,提出海底隧道复合衬砌合理注浆加固圈参数的确定方法,并在厦门翔安海底隧道穿越F4风化深槽的合理注浆加固圈参数设计中取得成功应用.研究结果可为海底隧道或富水区高水头山岭隧道工程的防排水系统设计提供借鉴和参考.%Different from land tunnels, the subsea tunnels are located deeply under the sea, so the groundwater treatment is the key issue during tunnel construction. Simultaneously, water inflow control and calculation of water load acting on lining structure are the core issues. The external water pressure on lining will be reduced remarkably with low discharge by adopting the design discipline of blocking groundwater and limiting discharge. So the design of lining structure in subsea tunnels is more economical. Based on the correlation theory of groundwater hydraulics, a calculation methods of water load acting on composite lining and water inflow in subsea tunnels is derived. Taking Xiang'an subsea tunnel in Xiamen for example, the influences of variable parameters of primary support, secondary support and grouting circle on water inflow and external water pressure are then expounded by using theoretical analysis and numerical

  15. Educational Wind Tunnel

    Directory of Open Access Journals (Sweden)

    Juozas Bielskus

    2012-12-01

    Full Text Available The paper analyzes an educational wind tunnel produced by the Department of Building Energetics (DBE of Vilnius Gediminas Technical University. The equipment could be used for performing laboratory works and simple research. The article presents the projection of inflow and outlet velocity in the working chamber of DBE wind tunnel and carries out actual noise level measurement. The received data are compared with information on the level of noise generated by the fan considering instructions provided by the manufacturer. In order to assess the reliability of the computer program, simulation applying PHOENICS software has been conducted. The aim of modeling is to simulate a pilot model and to compare the obtained results with those of an analogous test presented in scientific articles.Article in Lithuanian

  16. "Phantom" carpal tunnel syndrome.

    Science.gov (United States)

    Braverman, D L; Root, B C

    1997-10-01

    Phantom sensation is ubiquitous among persons who have had amputation; however, if it develops into phantom pain, a thorough clinical investigation must ensue. We illustrate this with the case of a 49-year-old woman, 14 years after traumatic amputation of her left 2nd through 5th fingers, and 10 years after traumatic left transfemoral amputation. She had had phantom sensation in her absent fingers for years and developed progressive pain in her phantom fingers 3 months before presentation. Nerve conduction study revealed a high-normal distal motor latency of the left median nerve and a positive Bactrian test (sensitivity 87%). She was diagnosed with "phantom" carpal tunnel syndrome and treated with a resting wrist splint, decreased weight bearing on the left upper limb, and two corticosteroid carpal tunnel injections with marked improvement. Clinicians should recognize that phantom pain may be referred from a more proximal region and may be amenable to conservative management.

  17. Carpal tunnel syndrome treatment

    Directory of Open Access Journals (Sweden)

    Emilio Filippucci

    2011-09-01

    Full Text Available Carpal tunnel syndrome, the most common peripheral neuropathy, results from compression of the median nerve at the wrist, and is a cause of pain, numbness and tingling in the upper extremities and an increasingly recognized cause of work disability. If carpal tunnel syndrome seems likely, conservative management with splinting should be initiated. Moreover, it has suggested that patients reduce activities at home and work that exacerbate symptoms. Pyridoxine and diuretics, since are largely utilised, are no more effective than placebo in relieving the symptoms. Non steroidal anti-inflammatory drugs and orally administered corticosteroids can be effective for short-term management (two to four weeks, but local corticosteroid injection may improve symptoms for a longer period. Injection is especially effective if there is no loss of sensibility or thenar-muscle atrophy and weakness, and if symptoms are intermittent rather than constant. If symptoms are refractory to conservative measures, the option of surgical therapy may be considered.

  18. [Carpal tunnel syndrome treatment].

    Science.gov (United States)

    De Angelis, Rossella; Salaffi, Fausto; Filippucci, Emilio; Grassi, Walter

    2006-01-01

    Carpal tunnel syndrome, the most common peripheral neuropathy, results from compression of the median nerve at the wrist, and is a cause of pain, numbness and tingling in the upper extremities and an increasingly recognized cause of work disability. If carpal tunnel syndrome seems likely, conservative management with splinting should be initiated. Moreover, it has suggested that patients reduce activities at home and work that exacerbate symptoms. Pyridoxine and diuretics, since are largely utilised, are no more effective than placebo in relieving the symptoms. Non steroidal anti-inflammatory drugs and orally administered corticosteroids can be effective for short-term management (two to four weeks), but local corticosteroid injection may improve symptoms for a longer period. Injection is especially effective if there is no loss of sensibility or thenar-muscle atrophy and weakness, and if symptoms are intermittent rather than constant. If symptoms are refractory to conservative measures, the option of surgical therapy may be considered.

  19. Programmable ferroelectric tunnel memristor

    Directory of Open Access Journals (Sweden)

    Andy eQuindeau

    2014-02-01

    Full Text Available We report an analogously programmable memristor based on genuine electronic resistive switching combining ferroelectric switching and electron tunneling. The tunnel current through an 8 unit cell thick epitaxial Pb(Zr[0.2]Ti[0.8]O[3] film sandwiched between La[0.7]Sr[0.3]MnO[3] and cobalt electrodes obeys the Kolmogorov-Avrami-Ishibashi model for bidimensional growth with a characteristic switching time in the order of 10^-7 seconds. The analytical description of switching kinetics allows us to develop a characteristic transfer function that has only one parameter viz. the characteristic switching time and fully predicts the resistive states of this type of memristor.

  20. The beam dump tunnels

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    In these images workers are digging the tunnels that will be used to dump the counter-circulating beams. Travelling just a fraction under the speed of light, the beams at the LHC will each carry the energy of an aircraft carrier travelling at 12 knots. In order to dispose of these beams safely, a beam dump is used to extract the beam and diffuse it before it collides with a radiation shielded graphite target.

  1. Carpal tunnel release

    DEFF Research Database (Denmark)

    Larsen, Morten Bo; Sørensen, A I; Crone, K L;

    2013-01-01

    A single-blind, randomized, controlled trial was done to compare the results of carpal tunnel release using classic incision, short incision, or endoscopic technique. In total, 90 consecutive cases were included. Follow-up was 24 weeks. We found a significantly shorter sick leave in the endoscopi...... incision could be found. There were no serious complications in either group. The results indicate that the endoscopic procedure is safe and has the benefit of faster rehabilitation and return to work....

  2. Discrete element analysis of the excavation effect of cross-river tunnel on the surroundings

    Directory of Open Access Journals (Sweden)

    Liu Dongyuan

    2017-01-01

    Full Text Available Cross-river tunnel as one of the underground constructions is complicated during its construction. For stability of tunnel excavation, it is emergency to analyze the dynamic characteristics of tunnel deformation under high water pressure. Therefore, a cross-river tunnel model is proposed based on DEM in this paper. Stiffness of particles decreases during excavation process which is as one of excavation methods. Porosity ratio of original porosity over its value at different excavation time has been considered. Radial displacements of particles at different angle around the tunnel are detected during excavation process. It shows that large deformation occurs at the vault of the excavation zone which accompanies with large radial displacement. The upper half of the tunnel performs larger deformation than the lower half part which results in many cracks in the concrete lining, the high water pressure may play an crucial role in it.

  3. 等里程间隔GM(1,1)模型在关角隧道6号斜井涌水量预测中的应用%Application of Equal Mileage Spacing Model GM(1,1) for Forecasting Water Gush in the No.6 Inclined Shaft of the Guanjiao Tunnel

    Institute of Scientific and Technical Information of China (English)

    赖明; 刘丹

    2011-01-01

    Based on the primitive gray GM (1,1) model, the water gush prediction in the No.6 inclined shaft of the Guanjiao tunnel is simulated by the model established and the equal mileage spacing sequence is analyzed. After examination, it is concluded that the prediction precision is high and that the model is practical for short-term prediction of water gush in tunnels.%在原始灰色GM(1,1)模型的基础上,通过运用等间距里程序列的分析方法建立模型,并对关角隧道6号斜井的涌水量进行了模拟预测.经检验,预测结果精度较高,对隧道工程涌水量的短期预测具有较大的实用价值.

  4. Theoretical and Numerical Investigations on Shallow Tunnelling in Unsaturated Soils

    Science.gov (United States)

    Soranzo, Enrico; Wu, Wei

    2013-04-01

    Excavation of shallow tunnels with the New Austrian Tunnelling Method (NATM) requires proper assessing of the tunnel face stability, to enable an open-face excavation, and the estimation of the correspondent surface settlements. Soils in a partially saturated condition exhibit a higher cohesion than in a fully saturated state, which can be taken into account when assessing the stability of the tunnel face. For the assessment of the face support pressure, different methods are used in engineering practice, varying from simple empirical and analytical formulations to advanced finite element analysis. Such procedures can be modified to account for the unsaturated state of soils. In this study a method is presented to incorporate the effect of partial saturation in the numerical analysis. The results are then compared with a simple analytical formulation derived from parametric studies. As to the numerical analysis, the variation of cohesion and of Young's modulus with saturation can be considered when the water table lies below the tunnel in a soil exhibiting a certain capillary rise, so that the tunnel is driven in a partially saturated layer. The linear elastic model with Mohr-Coulomb failure criterion can be extended to partially saturated states and calibrated with triaxial tests on unsaturated. In order to model both positive and negative pore water pressure (suction), Bishop's effective stress is incorporated into Mohr-Coulomb's failure criterion. The effective stress parameter in Bishop's formulation is related to the degree of saturation as suggested by Fredlund. If a linear suction distribution is assumed, the degree of saturation can be calculated from the Soil Water Characteristic Curve (SWCC). Expressions exist that relate the Young's modulus of unsaturated soils to the net mean stress and the matric suction. The results of the numerical computation can be compared to Vermeer & Ruse's closed-form formula that expresses the limit support pressure of the

  5. Effects of bituminous layer as backfill material on mechanical behavior in tunnel model

    OpenAIRE

    Moriyoshi, Akihiro; Takano, Shin-ei; Urata, Hiroyuki; Suzuki, Tetsuya; Yoshida, Takaki

    2001-01-01

    This paper describes the effects of bituminous material as a backfill material on mechanical behavior in model tunnel in laboratory. It is known that load spreading and relaxation of bituminous material are good properties. Then if we use bituminous material as a backfill material of tunnel, the tunnel will have waterproof, good load spreading property. We used new bituminous material (Aquaphalt) which can solidify in water. We conducted relaxation test in tension for new bituminous mat...

  6. Inelastic tunneling in superconducting junctions

    Energy Technology Data Exchange (ETDEWEB)

    Hlobil, Patrik Christian

    2016-06-10

    In this dissertation a theoretical formalism of elastic and inelastic tunneling spectroscopy is developed for superconductors. The underlying physical processes behind the different two tunneling channels and their implications for the interpretation of experimental tunneling data are investigated in detail, which can explain the background conductance seen in the cuprate and iron-based superconductors. Further, the properties of the emitted light from a superconducting LED are investigated.

  7. Gap anisotropy and tunneling currents. [MPS3

    DEFF Research Database (Denmark)

    Lazarides, N.; Sørensen, Mads Peter

    1996-01-01

    The tunneling Hamiltonian formalism is applied to calculate the tunnelingcurrents through a small superconducting tunnel junction. The formalism isextended to nonconstant tunneling matrix elements. The electrodes of thejunction are assumed to...

  8. Engineers win award for Swiss tunnel

    CERN Multimedia

    2003-01-01

    A Derby engineering consultancy has won the Tunnelling Industry Award 2003 for Excellence in Tunnel Design, offered by the British Tunnelling Society, for its work on the LHC in Geneva, Switzerland (1/2 page).

  9. Scanning Tunneling Microscopy

    Science.gov (United States)

    1992-03-17

    and c. M. Bertoni, J, Phys. C10, 1911 (1977); J, D. Joannoroulos and M.-r. Cohen, Phys. Rev. B10 , 5075 (1974); E. J, Mele and J. D. JOannopoulos...igh ’""f! nif ~<:ation.l’rc~mn.•hiy a pn.ltruJing ’-·luster or tJtnlp o{ a1onh at tb .. c:nd of ihis fint!t:r ad~ ~1s the tunnelling ti;". N ano

  10. A virtual detector approach to tunnel ionization and tunneling times

    CERN Document Server

    Teeny, Nicolas; Bauke, Heiko

    2016-01-01

    Tunneling times in atomic ionization is studied theoretically by a virtual detector approach. A virtual detector is a hypothetical device that allows to monitor the wave-function's density with spatial and temporal resolution during the ionization process. With this theoretical approach, it becomes possible to define unique moments when the electron enters and leaves with highest probability the classically forbidden region from first principles and a tunneling time can be specified unambiguously. It is shown that neither the moment when the electron enters the tunneling barrier nor when it leaves the tunneling barrier coincide with the moment when the external electric field reaches its maximum. Under the tunneling barrier as well as at the exit the electron has a nonzero velocity in electric field direction. This nonzero exit velocity has to be incorporated when the free motion of the electron is modeled by classical equations of motion.

  11. Tunnel face stability and ground settlement in pressurized shield tunnelling

    Institute of Scientific and Technical Information of China (English)

    苏艺; 汪国锋; 周庆宏

    2014-01-01

    An analysis of the stability of large-diameter circular tunnels and ground settlement during tunnelling by a pressurized shield was presented. An innovative three-dimensional translational multi-block failure mechanism was proposed to determine the face support pressure of large-shield tunnelling. Compared with the currently available mechanisms, the proposed mechanism has two unique features: (1) the supporting pressure applied to the tunnel face is assumed to have a non-uniform rather than uniform distribution, and (2) the method takes into account the entire circular excavation face instead of merely an inscribed ellipse. Based on the discrete element method, a numerical simulation of the Shanghai Yangtze River Tunnel was carried out using the Particle Flow Code in two dimensions. The immediate ground movement during excavation, as well as the behaviour of the excavation face, the shield movement, and the excavated area, was considered before modelling the excavation process.

  12. Magnetic tunnel junctions with monolayer hexagonal boron nitride tunnel barriers

    Energy Technology Data Exchange (ETDEWEB)

    Piquemal-Banci, M.; Galceran, R.; Bouzehouane, K.; Anane, A.; Petroff, F.; Fert, A.; Dlubak, B.; Seneor, P. [Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, Palaiseau 91767 (France); Caneva, S.; Martin, M.-B.; Weatherup, R. S.; Kidambi, P. R.; Robertson, J.; Hofmann, S. [Department of Engineering, University of Cambridge, Cambridge CB21PZ (United Kingdom); Xavier, S. [Thales Research and Technology, 1 avenue Augustin Fresnel, Palaiseau 91767 (France)

    2016-03-07

    We report on the integration of atomically thin 2D insulating hexagonal boron nitride (h-BN) tunnel barriers into Co/h-BN/Fe magnetic tunnel junctions (MTJs). The h-BN monolayer is directly grown by chemical vapor deposition on Fe. The Conductive Tip Atomic Force Microscopy (CT-AFM) measurements reveal the homogeneity of the tunnel behavior of our h-BN layers. As expected for tunneling, the resistance depends exponentially on the number of h-BN layers. The h-BN monolayer properties are also characterized through integration into complete MTJ devices. A Tunnel Magnetoresistance of up to 6% is observed for a MTJ based on a single atomically thin h-BN layer.

  13. Tunneling Ionization of Diatomic Molecules

    DEFF Research Database (Denmark)

    Svensmark, Jens Søren Sieg

    2016-01-01

    barriers, an ability classical particles do not possess. Tunnelling is a fundamental quantum mechanical process, a process that is distinctly non-classical, so solving this tunnelling problem is not only relevant for molecular physics, but also for quantum theory in general. In this dissertation the theory...

  14. The Analysis and Exposition on the Causes of F9 Fault Belt Water Gushing and Strengthening of Qingyunshan Mountain Extra-long Tunnel of Xiangpu Railway%向莆铁路青云山特长隧道F9断层带涌水原因分析与加固处理方案

    Institute of Scientific and Technical Information of China (English)

    毛建安

    2011-01-01

    对向莆铁路青云山特长隧道F9断层带的涌水原因进行了分析,对断层带涌水、坍塌的加固处理方案进行了论述,并谈了几点体会。%The causes to the F9 Fault Belt Water Gushing of Qingyunshan Mountain Extra-long Tunnel of Xiangpu Railway are analyzed and the strengthening treatment of water gushing and collapsing is discussed together with some experience.

  15. Design and Construction of Heat-keeping Water-proofing and Drainage System of Lafashan Tunnel in Extremely Cold Region%严寒地区拉法山隧道保温型防排水系统设计施工技术探讨

    Institute of Scientific and Technical Information of China (English)

    乐晟; 杨春勃; 杨艳玲

    2014-01-01

    严寒地区隧道结构因为地下水的存在,会长期出现冻胀的问题,经过冻融后,隧道结构易产生破坏,将大大影响结构的使用寿命。严寒地区的拉法山隧道从设计到施工,在“防、排、截、堵相结合,因地制宜,综合治理”的原则指导下,摸索出“先堵水、后排水、再防水”的防排水工程三要素。即先对围岩进行封闭注浆堵水,达到衬砌背后无水、少水的目的,再对衬砌背后增加聚氨酯保温层,保证衬砌背后不结冻;同时,采用在冻结线以下的深埋中央水沟,保证排水的通畅,解决了隧道在严寒环境下的冻胀问题。在施工技术上,开发了挂设聚氨酯保温层的施工方法,同时对止水带施工工艺进行优化,仰拱纵向钢边止水带、中埋式止水带和衬砌中埋止水带均采用了特制的定型钢模板施工,有效地解决了隧道防排水系统施工的质量通病。%Due to the existence of ground water,swelling and thawing caused by freezing always occur to tunnels located in extremely cold regions.Therefore,the tunnel structure may be damaged and the service life of the tunnel may be reduced.For the water-proofing and drainage of Lafashan tunnel,which is located in extremely cold region,the design principle of“water stopping,water draining and water sealing”is established,i.e.,water-stopping grouting is made to stop the ground water so as to minimize the water behind the lining,then heat-keeping layer is installed behind the lining to avoid freezing behind the lining,and finally central drainage ditch is built below the freezing level so as to ensure smooth water releasing.In this way,the problem of freezing swelling in extremely cold regions has been successfully solved .Regarding the construction of the water-proofing and drainage system,new heat-keeping layer installation method is developed,the water stop tie installation technique is optimized and

  16. Analysis of a groundwater inrush at -210 m north main tunnel in Guojiazhuang coal Mine

    Energy Technology Data Exchange (ETDEWEB)

    Bu, C.; Liang, M.; Qu, X. [Feicheng Mining Corporation, Feicheng (China). Guojiazhuang Coal Mine

    2001-10-01

    A groundwater inrush occurred with water amount reaching 32970 m{sup 3}/h at -210 m in the north main tunnel in Guojiazhuang Coal Mine of Feicheng Mining Area. The geologic structures near the water inrush point are complex, and different aquifers are in contact with each other. The severe inrush is a result of confined water gushing into the tunnel through weaknesses in the fractures. 1 fig., 1 tab.

  17. Tunneling magnetic force microscopy

    Science.gov (United States)

    Burke, Edward R.; Gomez, Romel D.; Adly, Amr A.; Mayergoyz, Isaak D.

    1993-01-01

    We have developed a powerful new tool for studying the magnetic patterns on magnetic recording media. This was accomplished by modifying a conventional scanning tunneling microscope. The fine-wire probe that is used to image surface topography was replaced with a flexible magnetic probe. Images obtained with these probes reveal both the surface topography and the magnetic structure. We have made a thorough theoretical analysis of the interaction between the probe and the magnetic fields emanating from a typical recorded surface. Quantitative data about the constituent magnetic fields can then be obtained. We have employed these techniques in studies of two of the most important issues of magnetic record: data overwrite and maximizing data-density. These studies have shown: (1) overwritten data can be retrieved under certain conditions; and (2) improvements in data-density will require new magnetic materials. In the course of these studies we have developed new techniques to analyze magnetic fields of recorded media. These studies are both theoretical and experimental and combined with the use of our magnetic force scanning tunneling microscope should lead to further breakthroughs in the field of magnetic recording.

  18. Carpal tunnel syndrome and acromegaly.

    Science.gov (United States)

    Baum, H; Lüdecke, D K; Herrmann, H D

    1986-01-01

    50 patients with acromegaly and carpal tunnel syndrome have been examined electrophysiologically before and after transnasal operation of the pituitary adenoma. 32 of the 50 patients (64%) had symptoms of carpal tunnel syndrome. 13 of them had neurological deficits. 28 of the examined patients had pathological neurographical findings only. About 1 week post-operatively DL was decreased in 43%; in 10 out of 13 patients with neurological deficits DL decreased. GH was normalized in 80% and reduced to 5-10 micrograms/l in a further 10%. The investigation did not show whether the carpal tunnel syndrome only depended on a GH increase or on other factors also such as e.g., on the duration of symptoms or tissue changes. None of the patients had the transversal carpal ligament operated on. The coincidence between acromegaly and carpal tunnel syndrome was 64%. In 3 cases the carpal tunnel syndrome was the leading sign to the diagnosis of acromegaly.

  19. Tunnel electroresistance through organic ferroelectrics

    Science.gov (United States)

    Tian, B. B.; Wang, J. L.; Fusil, S.; Liu, Y.; Zhao, X. L.; Sun, S.; Shen, H.; Lin, T.; Sun, J. L.; Duan, C. G.; Bibes, M.; Barthélémy, A.; Dkhil, B.; Garcia, V.; Meng, X. J.; Chu, J. H.

    2016-05-01

    Organic electronics is emerging for large-area applications such as photovoltaic cells, rollable displays or electronic paper. Its future development and integration will require a simple, low-power organic memory, that can be written, erased and readout electrically. Here we demonstrate a non-volatile memory in which the ferroelectric polarisation state of an organic tunnel barrier encodes the stored information and sets the readout tunnel current. We use high-sensitivity piezoresponse force microscopy to show that films as thin as one or two layers of ferroelectric poly(vinylidene fluoride) remain switchable with low voltages. Submicron junctions based on these films display tunnel electroresistance reaching 1,000% at room temperature that is driven by ferroelectric switching and explained by electrostatic effects in a direct tunnelling regime. Our findings provide a path to develop low-cost, large-scale arrays of organic ferroelectric tunnel junctions on silicon or flexible substrates.

  20. High-resolution tunnel fluctuoscopy

    Energy Technology Data Exchange (ETDEWEB)

    Glatz, A.; Varlamov, A. A.; Vinokur, V. M.

    2014-08-01

    Electron tunneling spectroscopy pioneered by Esaki and Giaever offered a powerful tool for studying electronic spectra and density of states (DOS) in superconductors. This led to important discoveries that revealed, in particular, the pseudogap in the tunneling spectrum of superconductors above their critical temperatures. However, the phenomenological approach of Giaever and Megerle does not resolve the fine structure of low-bias behavior carrying significant information about electron scattering, interactions, and decoherence effects. Here we construct a complete microscopic theory of electron tunneling into a superconductor in the fluctuation regime. We reveal a non-trivial low-energy anomaly in tunneling conductivity due to Andreev-like reflections of injected electrons from superconducting fluctuations. Our findings enable real-time observation of fluctuating Cooper pairs dynamics by time-resolved scanning tunneling microscopy measurements and open new horizons for quantitative analysis of the fluctuation electronic spectra of superconductors.

  1. Grouting techniques for the unfavorable geological conditions of Xiang'an subsea tunnel in China

    Directory of Open Access Journals (Sweden)

    Dingli Zhang

    2014-10-01

    Full Text Available One of the major challenges during subsea tunnel construction is to seal the potential water inflow. The paper presents a case study of Xiang'an subsea tunnel in Xiamen, the first subsea tunnel in China. During its construction, different grades of weathered geomaterials were encountered, which was the challenging issue for this project. To deal with these unfavorable geological conditions, grouting was adopted as an important measure for ground treatment. The grouting mechanism is first illustrated by introducing a typical grouting process. Then the site-specific grouting techniques employed in the Xiang'an subsea tunnel are elaborated. By using this ground reinforcement technique, the tunneling safety of the Xiang'an subsea tunnel was guaranteed.

  2. 厦深铁路梁山隧道L7断层大规模突水涌泥溃口封堵技术%Breach Blocking Technology for large-scale Water inrush and mud gush at L7 Fault in Liangshan Tunnel of Xiamen-Shenzhen Railway Line

    Institute of Scientific and Technical Information of China (English)

    林福地

    2012-01-01

    The article introduced the engineering geology condition of the L7 Fault of Liangshan Tunnel,then discussed the reason for water inrush and mud gush at L7 Fault of Liangshan Tunnel in detail,and finally proposed the key technique for design and construction on breach blocking.So the article may have high reference worth to design and construction of analogy engineering.%文章介绍了梁山隧道L7断层的工程地质条件,详细论述了该断层的突水涌泥的原因,最后提出了溃口封堵的设计、施工关键技术,对类似工程的设计与施工具有较高的参考价值。

  3. Sulphate reduction in the Aespoe HRL tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Gustafson, G. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Geology; Laaksoharju, M. [ed.; Skaarman, C. [GeoPoint AB, Sollentuna (Sweden); Pedersen, K. [Goeteborg Univ. (Sweden). Dept. of Genetics, Microbiology and Molecular Biology; Rhen, I. [VBB Viak (Sweden); Tullborg, E.L. [Terralogica AB (Sweden); Wallin, B. [Geokema AB (Sweden); Wikberg, P. [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    1995-12-01

    Evidence and indications of sulphate reduction based on geological, hydrogeological, groundwater, isotope and microbial data gathered in and around the Aespoe Hard Rock Laboratory tunnel have been evaluated. This integrated investigation showed that sulphate reduction had taken place in the past but is most likely also an ongoing process. Anaerobic sulphate-reducing bacteria can live in marine sediments, in the tunnel sections under the sea and in deep groundwaters, since there is no access to oxygen. The sulphate-reducing bacteria seem to thrive when the Cl{sup -} concentration of the groundwater is 4000-6000 mg/l. Sulphate reduction is an in situ process but the resulting hydrogen-sulphide rich water can be transported to other locations. A more vigorous sulphate reduction takes place when the organic content in the groundwater is high (>10 mg/l DOC) which is the case in the sediments and in the groundwaters under the sea. Some bacteria use hydrogen as an electron donor instead of organic carbon and can therefore live in deep environments where access to organic material is limited. The sulphate-reducing bacteria seem to adapt to changing flow situations caused by the tunnel construction relatively fast. Sulphate reduction seems to have occurred and will probably occur where conditions are favourable for the sulphate-reducing bacteria such as anaerobic brackish groundwater with dissolved sulphate and organic carbon or hydrogen. 59 refs, 37 figs, 6 tabs.

  4. Sulphate reduction in the Aespoe HRL tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Gustafson, G. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Geology; Laaksoharju, M. [ed.; Skaarman, C. [GeoPoint AB, Sollentuna (Sweden); Pedersen, K. [Goeteborg Univ. (Sweden). Dept. of Genetics, Microbiology and Molecular Biology; Rhen, I. [VBB Viak (Sweden); Tullborg, E.L. [Terralogica AB (Sweden); Wallin, B. [Geokema AB (Sweden); Wikberg, P. [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    1995-12-01

    Evidence and indications of sulphate reduction based on geological, hydrogeological, groundwater, isotope and microbial data gathered in and around the Aespoe Hard Rock Laboratory tunnel have been evaluated. This integrated investigation showed that sulphate reduction had taken place in the past but is most likely also an ongoing process. Anaerobic sulphate-reducing bacteria can live in marine sediments, in the tunnel sections under the sea and in deep groundwaters, since there is no access to oxygen. The sulphate-reducing bacteria seem to thrive when the Cl{sup -} concentration of the groundwater is 4000-6000 mg/l. Sulphate reduction is an in situ process but the resulting hydrogen-sulphide rich water can be transported to other locations. A more vigorous sulphate reduction takes place when the organic content in the groundwater is high (>10 mg/l DOC) which is the case in the sediments and in the groundwaters under the sea. Some bacteria use hydrogen as an electron donor instead of organic carbon and can therefore live in deep environments where access to organic material is limited. The sulphate-reducing bacteria seem to adapt to changing flow situations caused by the tunnel construction relatively fast. Sulphate reduction seems to have occurred and will probably occur where conditions are favourable for the sulphate-reducing bacteria such as anaerobic brackish groundwater with dissolved sulphate and organic carbon or hydrogen. 59 refs, 37 figs, 6 tabs.

  5. RESEARCH ON COUNTERMEASURE OF WATER GUSHING WITH COLLAPSE IN PROCESS OF WUSHAOLING HIGHWAY TUNNEL CROSSING F4 FAULT FRACTURE ZONE%高速公路乌鞘岭隧道穿越F4断层破碎带涌水塌方工程对策研究

    Institute of Scientific and Technical Information of China (English)

    李生杰; 谢永利; 朱小明

    2013-01-01

    针对高速公路乌鞘岭隧道穿越 F4断层破碎带发生的涌水塌方事故,结合地质情况和涌水塌方特征,采用地质勘察、现场实测、理论分析等研究方法,探讨乌鞘岭隧道涌水塌方机制及其导致的初期支护破坏的原因,分析其与断层破碎带围岩、地下水、地质构造之间的联系。本段涌水塌方属于断层破碎带引发的泥砾石型突涌灾害。在此基础上,研究涌水段和掌子面的支护设计及施工组织方案,提出相应的工程对策。现场监测结果显示,处治措施实施后,取得较为满意的效果,保证了复杂地质条件下隧道施工的安全。对类似条件下的隧道修建具有重要的指导作用和参考价值。%The water gushing with collapse in process of Wushaoling highway tunnel crossing F4 fault fracture zone is introduced. Combining with geological conditions of F4 fault fracture zone and features of water gushing with collapse,according to the methods of geological survey,field measurement and theoretical analysis,the mechanism of water gushing with collapse and the reasons of initial support failure caused by water gushing and collapse are investigated,and the inner links of which with the surrounding rocks,underground water and geologic structure are analyzed. The water crushing collapse is a kind of the gravel inrush hazard caused by the crushed belts of fault. The support design and construction organization scheme for segments with water gushing and tunnel face are researched,and treatment measures are proposed. According to the measurement results,it is shown that the treatment measures can achieve satisfying results and can ensure the safety of tunnel construction under complicated geological conditions. This research could play an important guiding role and provides a significant reference value for tunnel construction under similar conditions.

  6. Frequency driven inversion of tunnel magnetoimpedance and observation of positive tunnel magnetocapacitance in magnetic tunnel junctions

    Science.gov (United States)

    Parui, Subir; Ribeiro, Mário; Atxabal, Ainhoa; Bedoya-Pinto, Amilcar; Sun, Xiangnan; Llopis, Roger; Casanova, Fèlix; Hueso, Luis E.

    2016-08-01

    The relevance for modern computation of non-volatile high-frequency memories makes ac-transport measurements of magnetic tunnel junctions (MTJs) crucial for exploring this regime. Here, we demonstrate a frequency-mediated effect in which the tunnel magnetoimpedance reverses its sign in a classical Co/Al2O3/NiFe MTJ, whereas we only observe a gradual decrease in the tunnel magnetophase. Such effects are explained by the capacitive coupling of a parallel resistor and capacitor in the equivalent circuit model of the MTJ. Furthermore, we report a positive tunnel magnetocapacitance effect, suggesting the presence of a spin-capacitance at the two ferromagnet/tunnel-barrier interfaces. Our results are important for understanding spin transport phenomena at the high frequency regime in which the spin-polarized charge accumulation due to spin-dependent penetration depth at the two interfaces plays a crucial role.

  7. Frequency driven inversion of tunnel magnetoimpedance and observation of positive tunnel magnetocapacitance in magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Parui, Subir, E-mail: s.parui@nanogune.eu, E-mail: l.hueso@nanogune.eu; Ribeiro, Mário; Atxabal, Ainhoa; Llopis, Roger [CIC nanoGUNE, 20018 Donostia-San Sebastian (Spain); Bedoya-Pinto, Amilcar [CIC nanoGUNE, 20018 Donostia-San Sebastian (Spain); Max Planck Institute of Microstructure Physics, D-06120 Halle (Germany); Sun, Xiangnan [CIC nanoGUNE, 20018 Donostia-San Sebastian (Spain); National Center for Nanoscience and Technology, 100190 Beijing (China); Casanova, Fèlix; Hueso, Luis E., E-mail: s.parui@nanogune.eu, E-mail: l.hueso@nanogune.eu [CIC nanoGUNE, 20018 Donostia-San Sebastian (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain)

    2016-08-01

    The relevance for modern computation of non-volatile high-frequency memories makes ac-transport measurements of magnetic tunnel junctions (MTJs) crucial for exploring this regime. Here, we demonstrate a frequency-mediated effect in which the tunnel magnetoimpedance reverses its sign in a classical Co/Al{sub 2}O{sub 3}/NiFe MTJ, whereas we only observe a gradual decrease in the tunnel magnetophase. Such effects are explained by the capacitive coupling of a parallel resistor and capacitor in the equivalent circuit model of the MTJ. Furthermore, we report a positive tunnel magnetocapacitance effect, suggesting the presence of a spin-capacitance at the two ferromagnet/tunnel-barrier interfaces. Our results are important for understanding spin transport phenomena at the high frequency regime in which the spin-polarized charge accumulation due to spin-dependent penetration depth at the two interfaces plays a crucial role.

  8. Simulations in quantum tunneling

    Science.gov (United States)

    Smith, Kevin; Blaylock, Guy

    2017-10-01

    We study the timing effects of nonrelativistic wave packet tunneling through a barrier using a numerical simulation readily accessible to an undergraduate audience. We demonstrate that the peak of the transmitted packet can sometimes emerge from the barrier ahead of the peak of an undisturbed wave packet that does not encounter a barrier. Under the right circumstances, this effect can give the appearance that transmission through the barrier occurs at superluminal speeds. We demonstrate that this seemingly paradoxical effect is not all that puzzling. Rather, components from the front of the incoming wave packet are preferentially transmitted, forming a transmitted packet ahead of the average of the incoming wave packet but not ahead of the leading edge of that packet. Our studies also show how the timing depends on barrier height and width, consistent with expectations based on the different energy components of the wave packet.

  9. Water

    Science.gov (United States)

    ... www.girlshealth.gov/ Home Nutrition Nutrition basics Water Water Did you know that water makes up more ... to drink more water Other drinks How much water do you need? top Water is very important, ...

  10. Tunneling of atoms, nuclei and molecules

    CERN Document Server

    Bertulani, C A

    2015-01-01

    This is a brief review of few relevant topics on tunneling of composite particles and how the coupling to intrinsic and external degrees of freedom affects tunneling probabilities. I discuss the phenomena of resonant tunneling, different barriers seen by subsystems, damping of resonant tunneling by level bunching and continuum effects due to particle dissociation.

  11. Tunnel fire testing and modeling the Morgex North tunnel experiment

    CERN Document Server

    Borghetti, Fabio; Gandini, Paolo; Frassoldati, Alessio; Tavelli, Silvia

    2017-01-01

    This book aims to cast light on all aspects of tunnel fires, based on experimental activities and theoretical and computational fluid dynamics (CFD) analyses. In particular, the authors describe a transient full-scale fire test (~15 MW), explaining how they designed and performed the experimental activity inside the Morgex North tunnel in Italy. The entire organization of the experiment is described, from preliminary evaluations to the solutions found for management of operational difficulties and safety issues. This fire test allowed the collection of different measurements (temperature, air velocity, smoke composition, pollutant species) useful for validating and improving CFD codes and for testing the real behavior of the tunnel and its safety systems during a diesel oil fire with a significant heat release rate. Finally, the fire dynamics are compared with empirical correlations, CFD simulations, and literature measurements obtained in other similar tunnel fire tests. This book will be of interest to all ...

  12. EXPERIMENTS OF HYDRODYNAMICS AND STABILITY OF IMMERSED TUBE TUNNEL ON TRANSPORTATION AND IMMERSING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Effects of environment conditions, such as current, wave etc., are more important for immersed tube tunnel’s transportation and immersing. The hydrodynamics and stability of immersed tube tunnel during its towing and immersing are intersted for departments of design and construction. A serial model tests are made in towing tank and water channel for Nanjing immersed tube tunnel, and the first immersed tunnel has been designed in Yangtzi River in China. The hydrodynamic forces and rope tensions of the tunnel are measured with strain balances when it is towed by ship and immersed by winches for a different current velocity and wave height. In addition, the stability of tunnel for a different ballast water is tested and discussed.

  13. Tunnel Cost-Estimating Methods.

    Science.gov (United States)

    1981-10-01

    8 ae1e 066 c LINING CALCULATES THE LINING COSTS AND THE FORMWORK COST FOR A 982928 ees C TUNNEL OR SHAFT SEGMENT 682636 0066...AD-AIO . 890 ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURGETC F/B 13/13 TUNNEL COST-ESTIMATING METNDS(U) OCT 81 R D BENNETT UNCLASSIFIED WES...TR/L-81-101-3lEEEEEE EIIIl-IIIIIIIu IIIIEIIIEIIIIE llllEEEEllEEEI EEEEEEEEEIIII C EllTE-CHNICAL RGPORT GL-81-10 LI10 TUNNEL COST-ESTIMATING METHODS by

  14. Quantum Tunneling and Complex Trajectories

    Science.gov (United States)

    Meynig, Max; Haggard, Hal

    2017-01-01

    In general, the semiclassical approximation of quantum mechanical tunneling fails to treat tunneling through barriers if real initial conditions and trajectories are used. By analytically continuing classical dynamics to the complex plane the problems encountered in the approximation can be resolved. While, the complex methods discussed here have been previously explored, no one has exhibited an analytically solvable case. The essential features of the complex method will be discussed in the context of a novel, analytically solvable problem. These methods could be useful in quantum gravity, with applications to the tunneling of spacetime geometries.

  15. Tunneling Ionization of Diatomic Molecules

    DEFF Research Database (Denmark)

    Svensmark, Jens Søren Sieg

    2016-01-01

    When a molecule is subject to a strong laser field, there is a probability that an electron can escape, even though the electrons are bound by a large potential barrier. This is possible because electrons are quantum mechanical in nature, and they are therefore able to tunnel through potential...... of tunneling ionizaion of molecules is presented and the results of numerical calculations are shown. One perhaps surprising result is, that the frequently used Born-Oppenheimer approximation breaks down for weak fields when describing tunneling ionization. An analytic theory applicable in the weak-field limit...

  16. Dynamical tunneling theory and experiment

    CERN Document Server

    Keshavamurthy, Srihari

    2011-01-01

    A prominent aspect of quantum theory, tunneling arises in a variety of contexts across several fields of study, including nuclear, atomic, molecular, and optical physics and has led to technologically relevant applications in mesoscopic science. Exploring mechanisms and consequences, Dynamical Tunneling: Theory and Experiment presents the work of international experts who discuss the considerable progress that has been achieved in this arena in the past two decades.Highlights in this volume include:A historical introduction and overview of dynamical tunneling, with case histories ranging from

  17. Geological Hazards analysis in Urban Tunneling by EPB Machine (Case study: Tehran subway line 7 tunnel

    Directory of Open Access Journals (Sweden)

    Hassan Bakhshandeh Amnieh

    2016-06-01

    Full Text Available Technological progress in tunneling has led to modern and efficient tunneling methods in vast underground spaces even under inappropriate geological conditions. Identification and access to appropriate and sufficient geological hazard data are key elements to successful construction of underground structures. Choice of the method, excavation machine, and prediction of suitable solutions to overcome undesirable conditions depend on geological studies and hazard analysis. Identifying and investigating the ground hazards in excavating urban tunnels by an EPB machine could augment the strategy for improving soil conditions during excavation operations. In this paper, challenges such as geological hazards, abrasion of the machine cutting tools, clogging around these tools and inside the chamber, diverse work front, severe water level fluctuations, existence of water, and fine-grained particles in the route were recognized in a study of Tehran subway line 7, for which solutions such as low speed boring, regular cutter head checks, application of soil improving agents, and appropriate grouting were presented and discussed. Due to the presence of fine particles in the route, foam employment was suggested as the optimum strategy where no filler is needed.

  18. FEASIBILITY TESTING AND INVESTIGATION ON A NEW TECHNOLOGY FOR HARD ROCK TUNNELING WITH A COLLIMATED ABRASIVE WATER JET%采用准直管磨料射流掘进硬岩巷(隧) 道的可行性试验与探讨

    Institute of Scientific and Technical Information of China (English)

    李晓红; 王建生; 杨林; 卢义玉; 孙家骏

    2001-01-01

    为了提高坚硬岩石巷道的掘进速度和质量,研究了准直管磨料射流用于岩石巷道掘进的方案,分析了准直管磨料射流装备的结构特点和工作原理。试验研究了准直管结构参数、磨料参数、进给速度对射流切割效果的影响。初步研究表明这一设想基本可行,是一种值得探讨的新型掘进方法。%A new-type tunneling system, Collimated Abrasive Water Jet(CAWJ)cutter, is develped to increase the tunneling speed and improve the cutting quality in hard rock. And its characteristics of configuration and operating principle are discussed. The effects of cutting hard rock with various operating parameters on the cutting efficiency of CAWJ are analyzed. Research results show that it is primarily feasible for tunneling hard rock with CAWJ.

  19. Flatback airfoil wind tunnel experiment.

    Energy Technology Data Exchange (ETDEWEB)

    Mayda, Edward A. (University of California, Davis, CA); van Dam, C.P. (University of California, Davis, CA); Chao, David D. (University of California, Davis, CA); Berg, Dale E.

    2008-04-01

    A computational fluid dynamics study of thick wind turbine section shapes in the test section of the UC Davis wind tunnel at a chord Reynolds number of one million is presented. The goals of this study are to validate standard wind tunnel wall corrections for high solid blockage conditions and to reaffirm the favorable effect of a blunt trailing edge or flatback on the performance characteristics of a representative thick airfoil shape prior to building the wind tunnel models and conducting the experiment. The numerical simulations prove the standard wind tunnel corrections to be largely valid for the proposed test of 40% maximum thickness to chord ratio airfoils at a solid blockage ratio of 10%. Comparison of the computed lift characteristics of a sharp trailing edge baseline airfoil and derived flatback airfoils reaffirms the earlier observed trend of reduced sensitivity to surface contamination with increasing trailing edge thickness.

  20. Self-Organizing Tunnel Peers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Tunneling is an important approach in IPv6 transition techniques. The tunnel broker model provides a way to build virtual IPv6 networks without manual configuration.However, neither it adapts performance variation on the IPv4 infrastructure,nor it is a scalable solution for a wide-area IPv6 networking environment. In this paper, a self-organizing tunnel peer (SOTP)model is presented. Tunnel peers are clustered in the SOTP system so that optimization is scalable. Four primitive operations related to cluster construction - arrest,release,division and death - endow the system with the nature of self-organization.Occurrence and behavior of the operations are decided by criteria on the IPv4 end-to-end performance; hence measurement is an indispensable component of the system. The metabolism of cluster relaxes the requirement to accuracy of measurement and optimization.

  1. The Statistics of Chaotic Tunnelling

    CERN Document Server

    Creagh, S C; Creagh, Stephen C.; Whelan, Niall D.

    2000-01-01

    We discuss the statistics of tunnelling rates in the presence of chaotic classical dynamics. This applies to resonance widths in chaotic metastable wells and to tunnelling splittings in chaotic symmetric double wells. The theory is based on using the properties of a semiclassical tunnelling operator together with random matrix theory arguments about wave function overlaps. The resulting distribution depends on the stability of a specific tunnelling orbit and is therefore not universal. However it does reduce to the universal Porter-Thomas form as the orbit becomes very unstable. For some choices of system parameters there are systematic deviations which we explain in terms of scarring of certain real periodic orbits. The theory is tested in a model symmetric double well problem and possible experimental realisations are discussed.

  2. Hysteresis of boiling for different tunnel-pore surfaces

    Directory of Open Access Journals (Sweden)

    Pastuszko Robert

    2015-01-01

    Full Text Available Analysis of boiling hysteresis on structured surfaces covered with perforated foil is proposed. Hysteresis is an adverse phenomenon, preventing high heat flux systems from thermal stabilization, characterized by a boiling curve variation at an increase and decrease of heat flux density. Experimental data were discussed for three kinds of enhanced surfaces: tunnel structures (TS, narrow tunnel structures (NTS and mini-fins covered with the copper wire net (NTS-L. The experiments were carried out with water, R-123 and FC-72 at atmospheric pressure. A detailed analysis of the measurement results identified several cases of type I, II and III for TS, NTS and NTS-L surfaces.

  3. Energy analysis of stability of twin shallow tunnels based on nonlinear failure criterion

    Institute of Scientific and Technical Information of China (English)

    张佳华; 许敬叔; 张标

    2014-01-01

    Based on nonlinear Mohr−Coulomb failure criterion, the analytical solutions of stability number and supporting force on twin shallow tunnels were derived using upper bound theorem of limit analysis. The optimized solutions were obtained by the technique of sequential quadratic programming. When nonlinear coefficient equals 1 and internal friction angle equals 0, the nonlinear Mohr−Coulomb failure criterion degenerates into linear failure criterion. The calculated results of stability number in this work were compared with previous results, and the agreement verifies the effectiveness of the present method. Under the condition of nonlinear Mohr−Coulomb failure criterion, the results show that the supporting force on twin shallow tunnels obviously increases when the nonlinear coefficient, burial depth, ground load or pore water pressure coefficients increase. When the clear distance is 0.5 to 1.0 times the diameter of tunnel, the supporting force of twin shallow tunnels reaches its maximum value, which means that the tunnels are the easiest to collapse. While the clear distance increases to 3.5 times the diameter of tunnel, the calculation for twin shallow tunnels can be carried out by the method for independent single shallow tunnel. Therefore, 3.5 times the diameter of tunnel serves as a critical value to determine whether twin shallow tunnels influence each other. In designing twin shallow tunnels, appropriate clear distance value must be selected according to its change rules and actual topographic conditions, meanwhile, the influences of nonlinear failure criterion of soil materials and pore water must be completely considered. During the excavation process, supporting system should be intensified at the positions of larger burial depth or ground load to avoid collapses.

  4. 5-foot Vertical Wind Tunnel

    Science.gov (United States)

    1932-01-01

    The researcher is sitting above the exit cone of the 5-foot Vertical Wind Tunnel and is examining the new 6-component spinning balance. This balance was developed between 1930 and 1933. It was an important advance in the technology of rotating or rolling balances. As M.J. Bamber and C.H. Zimmerman wrote in NACA TR 456: 'Data upon the aerodynamic characteristics of a spinning airplane may be obtained in several ways; namely, flight tests with full-scale airplanes, flight tests with balanced models, strip-method analysis of wind-tunnel force and moment tests, and wind-tunnel tests of rotating models.' Further, they note: 'Rolling-balance data have been of limited value because it has not been possible to measure all six force and moment components or to reproduce a true spinning condition. The spinning balance used in this investigation is a 6-component rotating balance from which it is possible to obtain wind-tunnel data for any of a wide range of possible spinning conditions.' Bamber and Zimmerman described the balance as follows: 'The spinning balance consists of a balance head that supports the model and contains the force-measuring units, a horizontal turntable supported by streamline struts in the center of the jet and, outside the tunnel, a direct-current driving motor, a liquid tachometer, an air compressor, a mercury manometer, a pair of indicating lamps, and the necessary controls. The balance head is mounted on the turntable and it may be set to give any radius of spin between 0 and 8 inches.' In an earlier report, NACA TR 387, Carl Wenzinger and Thomas Harris supply this description of the tunnel: 'The vertical open-throat wind tunnel of the National Advisory Committee for Aeronautics ... was built mainly for studying the spinning characteristics of airplane models, but may be used as well for the usual types of wind-tunnel tests. A special spinning balance is being developed to measure the desired forces and moments with the model simulating the actual

  5. Hydrogeochemical effects of a bulkhead in the Dinero mine tunnel, Sugar Loaf mining district, near Leadville, Colorado

    Science.gov (United States)

    Walton-Day, Katherine; Mills, Taylor J.

    2015-01-01

    The Dinero mine drainage tunnel is an abandoned, draining mine adit near Leadville, Colorado, that has an adverse effect on downstream water quality and aquatic life. In 2009, a bulkhead was constructed (creating a mine pool and increasing water-table elevations behind the tunnel) to limit drainage from the tunnel and improve downstream water quality. The goal of this study was to document changes to hydrology and water quality resulting from bulkhead emplacement, and to understand post-bulkhead changes in source water and geochemical processes that control mine-tunnel discharge and water quality. Comparison of pre-and post-bulkhead hydrology and water quality indicated that tunnel discharge and zinc and manganese loads decreased by up to 97 percent at the portal of Dinero tunnel and at two downstream sites (LF-537 and LF-580). However, some water-quality problems persisted at LF-537 and LF-580 during high-flow events and years, indicating the effects of the remaining mine waste in the area. In contrast, post-bulkhead water quality degraded at three upstream stream sites and a draining mine tunnel (Nelson tunnel). Water-quality degradation in the streams likely occurred from increased contributions of mine-pool groundwater to the streams. In contrast, water-quality degradation in the Nelson tunnel was likely from flow of mine-pool water along a vein that connects the Nelson tunnel to mine workings behind the Dinero tunnel bulkhead. Principal components analysis, mixing analysis, and inverse geochemical modeling using PHREEQC indicated that mixing and geochemical reactions (carbonate dissolution during acid weathering, precipitation of goethite and birnessite, and sorption of zinc) between three end-member water types generally explain the pre-and post-bulkhead water composition at the Dinero and Nelson tunnels. The three end members were (1) a relatively dilute groundwater having low sulfate and trace element concentrations; (2) mine pool water, and (3) water that

  6. Critical review of wind tunnel modeling of atmospheric heat dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Orgill, M.M.

    1977-05-01

    There is increasing concern by scientists that future proposed energy or power parks may significantly affect the environment by releasing large quantities of heat and water vapor to the atmosphere. A critical review is presented of the potential application of physical modeling (wind tunnels) to assess possible atmospheric effects from heat dissipation systems such as cooling towers. A short inventory of low-speed wind tunnel facilities is included in the review. The useful roles of wind tunnels are assessed and the state-of-the-art of physical modeling is briefly reviewed. Similarity criteria are summarized and present limitations in satisfying these criteria are considered. Current physical models are defined and limitations are discussed. Three experimental problems are discussed in which physical modeling may be able to provide data. These are: defining the critical atmospheric heat load; topographic and local circulation effects on thermal plumes; and plume rise and downstream effects.

  7. Submucosal tunneling techniques: current perspectives

    Directory of Open Access Journals (Sweden)

    Kobara H

    2014-04-01

    Full Text Available Hideki Kobara,1 Hirohito Mori,1 Kazi Rafiq,2 Shintaro Fujihara,1 Noriko Nishiyama,1 Maki Ayaki,1 Tatsuo Yachida,1 Tae Matsunaga,1 Johji Tani,1 Hisaaki Miyoshi,1 Hirohito Yoneyama,1 Asahiro Morishita,1 Makoto Oryu,1 Hisakazu Iwama,3 Tsutomu Masaki1 1Department of Gastroenterology and Neurology, 2Department of Pharmacology, 3Life Science Research Center, Faculty of Medicine, Kagawa University, Miki-cho, Kita-Gun, Kagawa, Japan Abstract: Advances in endoscopic submucosal dissection include a submucosal tunneling technique, involving the introduction of tunnels into the submucosa. These tunnels permit safer offset entry into the peritoneal cavity for natural orifice transluminal endoscopic surgery. Technical advantages include the visual identification of the layers of the gut, blood vessels, and subepithelial tumors. The creation of a mucosal flap that minimizes air and fluid leakage into the extraluminal cavity can enhance the safety and efficacy of surgery. This submucosal tunneling technique was adapted for esophageal myotomy, culminating in its application to patients with achalasia. This method, known as per oral endoscopic myotomy, has opened up the new discipline of submucosal endoscopic surgery. Other clinical applications of the submucosal tunneling technique include its use in the removal of gastrointestinal subepithelial tumors and endomicroscopy for the diagnosis of functional and motility disorders. This review suggests that the submucosal tunneling technique, involving a mucosal safety flap, can have potential values for future endoscopic developments. Keywords: submucosal endoscopy, submucosal tunneling method, natural orifice transluminal endoscopic surgery, peroral endoscopic myotomy, gastrointestinal subepithelial tumor, functional and motility disorders

  8. Aespoe HRL. Experiences of blasting of the TASQ tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Mats [Swebrec, Luleaa (Sweden); Niklasson, Bengt [Skanska Teknik, Stockholm (Sweden); Wilson, Lasse [Skanska Stora Projekt, Stockholm (Sweden); Andersson, Christer; Christiansson, Rolf [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    2004-11-01

    length in the tunnel wall was roughly 0.2 m. However, longer cracks existed but these cracks probably originate from water filled blast holes. The cracks from the bench were generally much shorter than what is normally achieved during excavation of a horse-shoe shaped tunnel. This may be due to the stress situation under the arched bottom profile, the height requirement on drilling precision also in the floor as well as the low confinement in the arch shaped contour of the floor: Some conclusions from the APSE tunnel: There is a demand for new drilling equipment with a better guidance control to increase the drilling accuracy. Electronic detonators have very good accuracy and a high potential to reduce cracks from blasting. However, they must be more easy to use. It is possible to minimize the damage zone in the floor by using top heading and bench. However, there is a demand for more development in order to minimize the damage zone in the floor without a separate bench. Water in bore holes increases the damage zone in terms of length and frequency of induced fractures. This could be avoided by drilling the holes pointing slightly upwards. The look-out angle and distribution of specific charge along each round causes a discontinuous EDZ along the tunnel. It is therefore indicated that the impact of the EDZ on hydraulic conductivity along the tunnel has very limited impact. During similar conditions is it believed that the extent of the EDZ is manageable through DandB design and QA control during excavation.

  9. Upper bound analysis for deep tunnel face with joined failure mechanism of translation and rotation

    Institute of Scientific and Technical Information of China (English)

    许敬叔; 杜佃春; 杨子汉

    2015-01-01

    A joined failure mechanism of translation and rotation was proposed for the stability analysis of deep tunnel face, and the upper bound solution of supporting force of deep tunnel was calculated under pore water pressure. The calculations were based on limit analysis method of upper bound theory, with the employment of non-associated Mohr-Coulomb flow rule. Nonlinear failure criterion was adopted. Optimized analysis was conducted for the effects of the tunnel depth, pore water pressure coefficient, the initial cohesive force and nonlinear coefficient on supporting force. The upper bound solutions are obtained by optimum method. Results are listed and compared with the previously published solutions for the verification of correctness and effectiveness. The failure shapes are presented, and results are discussed for different pore water pressure coefficients and nonlinear coefficients of tunnel face.

  10. Analysis of mechanical behavior of soft rocks and stability control in deep tunnels

    Directory of Open Access Journals (Sweden)

    Hui Zhou

    2014-06-01

    Full Text Available Due to the weakness in mechanical properties of chlorite schist and the high in situ stress in Jinping II hydropower station, the rock mass surrounding the diversion tunnels located in chlorite schist was observed with extremely large deformations. This may significantly increase the risk of tunnel instability during excavation. In order to assess the stability of the diversion tunnels laboratory tests were carried out in association with the petrophysical properties, mechanical behaviors and water-weakening properties of chlorite schist. The continuous deformation of surrounding rock mass, the destruction of the support structure and a large-scale collapse induced by the weak chlorite schist and high in situ stress were analyzed. The distributions of compressive deformation in the excavation zone with large deformations were also studied. In this regard, two reinforcement schemes for the excavation of diversion tunnel bottom section were proposed accordingly. This study could offer theoretical basis for deep tunnel construction in similar geological conditions.

  11. Analysis of mechanical behavior of soft rocks and stability control in deep tunnels

    Institute of Scientific and Technical Information of China (English)

    Hui Zhou; Chuanqing Zhang; Zhen Li; Dawei Hu; Jing Hou

    2014-01-01

    Due to the weakness in mechanical properties of chlorite schist and the high in situ stress in Jinping II hydropower station, the rock mass surrounding the diversion tunnels located in chlorite schist was observed with extremely large deformations. This may significantly increase the risk of tunnel instability during excavation. In order to assess the stability of the diversion tunnels laboratory tests were carried out in association with the petrophysical properties, mechanical behaviors and water-weakening properties of chlorite schist. The continuous deformation of surrounding rock mass, the destruction of the support structure and a large-scale collapse induced by the weak chlorite schist and high in situ stress were analyzed. The distributions of compressive deformation in the excavation zone with large deformations were also studied. In this regard, two reinforcement schemes for the excavation of diversion tunnel bottom section were proposed accordingly. This study could offer theoretical basis for deep tunnel construction in similar geological conditions.

  12. Current noise in tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Frey, Moritz; Grabert, Hermann [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104, Freiburg (Germany)

    2017-06-15

    We study current fluctuations in tunnel junctions driven by a voltage source. The voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. We use circuit theory to relate the fluctuations of the current flowing in the leads of the junction with the voltage fluctuations generated by the environmental impedance and the fluctuations of the tunneling current. The spectrum of current fluctuations is found to consist of three parts: a term arising from the environmental Johnson-Nyquist noise, a term due to the shot noise of the tunneling current and a third term describing the cross-correlation between these two noise sources. Our phenomenological theory reproduces previous results based on the Hamiltonian model for the dynamical Coulomb blockade and provides a simple understanding of the current fluctuation spectrum in terms of circuit theory and properties of the average current. Specific results are given for a tunnel junction driven through a resonator. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. TunnelVision: LHC Tunnel Photogrammetry System for Structural Monitoring

    CERN Document Server

    Fallas, William

    2014-01-01

    In this document an algorithm to detect deformations in the LHC Tunnel of CERN is presented. It is based on two images, one represents the ideal state of the tunnel and the other one the actual state. To find the differences between both, the algorithm is divided in three steps. First, an image enhancement is applied to make easier the detection. Second, two different approaches to reduce noise are applied to one or both images. And third, it is defined a group of characteristics about the type of deformation desired to detect. Finally, the conclusions show the effectiveness of the algorithm in the experimental results.

  14. Pool boiling on rectangular fins with tunnel-pore structure

    Directory of Open Access Journals (Sweden)

    Pastuszko A.

    2013-04-01

    Full Text Available Complex experimental investigations were conducted in the area of pool boiling heat transfer on extended surfaces with internal tunnels limited by perforated foil. The experiments were carried out for water and R-123 at atmospheric pressure. The tunnel surfaces were fabricated from 0.05 – 0.1 mm thick perforated copper foil (pore diameters: 0.3, 0.4, 0.5 mm sintered with mini-fins formed by 5 and 10 mm high rectangular fins and horizontal inter-fin surface. The effect of the main fin height, pore diameters and tunnel pitch on nucleate pool boiling was examined. Substantial enhancement of heat transfer coefficient was observed for the investigated surfaces. The highest increase in the heat transfer coefficient was obtained for the 10 mm high fins – about 50kW/m2K for water and 15 kW/m2K for R-123. The investigated surfaces showed boiling heat transfer coefficients similar to those of existing tunnel-pore structures.

  15. Design of tunneling injection quantum dot lasers

    Institute of Scientific and Technical Information of China (English)

    JIA Guo-zhi; YAO Jiang-hong; SHU Yong-chun; WANG Zhan-guo

    2007-01-01

    To implement high quality tunneling injection quantum dot lasers,effects of primary factors on performance of the tunneling injection quantum dot lasers were investigated. The considered factors were tunneling probability,tunneling time and carriers thermal escape time from the quantum well. The calculation results show that with increasing of the ground-state energy level in quantum well,the tunneling probability increases and the tunneling time decreases,while the thermal escape time decreases because the ground-state energy levelis shallower. Longitudinal optical phonon-assisted tunneling can be an effective method to solve the problem that both the tunneling time and the thermal escape time decrease simultaneously with the ground-state energy level increasing in quantum well.

  16. Rock mechanical conditions at the Aespoe HRL. A study of the correlation between geology, tunnel maintenance and tunnel shape

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Christer [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Soederhaell, Joergen [SWECO VBB VIAK AB, Stockholm (Sweden)

    2001-12-01

    the horseshoe shaped tunnel TASF at the 450 m level has been compared to the maintenance work in the adjacent TBM tunnel. No maintenance has been performed in the TBM tunnel but TASF have been scaled and bolted several time and was finally shotcreted. The TASF tunnel has some larger areas with Smaaland granite and fine-grained granite. The modelling does not indicate problems due to stress concentrations. It is therefore probable that the granites are rather fractured and therefore needs more scaling. The water flow in the Aespoe HRL is continually monitored. During the first five years of operation the water flow has had an average decrease of approximately 4% per year. The water flow in two other facilities owned by SKB, SFR and CLAB has been monitored for the last 12 years. These two facilities also show a decrease of the water flow of approximately 4% per year.

  17. Tunneling field effect transistor technology

    CERN Document Server

    Chan, Mansun

    2016-01-01

    This book provides a single-source reference to the state-of-the art in tunneling field effect transistors (TFETs). Readers will learn the TFETs physics from advanced atomistic simulations, the TFETs fabrication process and the important roles that TFETs will play in enabling integrated circuit designs for power efficiency. · Provides comprehensive reference to tunneling field effect transistors (TFETs); · Covers all aspects of TFETs, from device process to modeling and applications; · Enables design of power-efficient integrated circuits, with low power consumption TFETs.

  18. Quantum Cosmology for Tunneling Universes

    CERN Document Server

    Kim, Sang Pyo

    2004-01-01

    In a quantum cosmological model consisting of a Euclidean region and a Lorentzian region, Hartle-Hawking's no-bounary wave function, and Linde's wave function and Vilenkin's tunneling wave function are briefly described and compared with each other. We put a particular emphasis on semiclassical gravity from quantum cosmology and compare it with the conventional quantum field theory in curved spacetimes. Finally, we discuss the recent debate on catastrophic particle production in the tunneling universe between Rubakov and Vilenkin within the semiclassical gravity.

  19. Spin tunnelling in mesoscopic systems

    Indian Academy of Sciences (India)

    Anupam Garg

    2001-02-01

    We study spin tunnelling in molecular magnets as an instance of a mesoscopic phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel splitting between various pairs of Zeeman levels in this molecule oscillates as a function of applied magnetic field, vanishing completely at special points in the space of magnetic fields, known as diabolical points. This phenomena is explained in terms of two approaches, one based on spin-coherent-state path integrals, and the other on a generalization of the phase integral (or WKB) method to difference equations. Explicit formulas for the diabolical points are obtained for a model Hamiltonian.

  20. Countermeasures for Disaster of High-pressured Water-rich Metamorphic Strata and Tectonic Zone of Jiubao Large Cross-section Tunnel%大断面隧道高压富水变质岩地层及构造带灾害处理技术--以旧堡隧道为例

    Institute of Scientific and Technical Information of China (English)

    孟庆余; 苏江; 方伟

    2016-01-01

    Jiubao tunnel is located in the junction of regional tectonic whose main strata is old archaeozoic metamorphic rocks.The fault structure is developed well due to the geological structural movement.The groundwater is rich;and there is confined water in partial sections.Technologies,such as the temporary inverted arch,the temporary retaining wall,strengthening and avoidance are used so as to solve the water inrush and collapse of tunnel face.In order to guarantee the safety of tunnel lining structure,advance grouting,advance pipe roof and double primary support layers are adopted.In light of the rich groundwater,the drainage-type waterproofing plate,additional macadam blind drains and increasing drainage holes are adopted to guarantee the running safety of the tunnel.%旧堡隧道地处区域性构造交汇部位,地层为古老的太古界变质岩,岩石因受多期地质构造运动作用,断裂构造极为发育。隧道地下水发育且部分地段存在承压水,在施工过程中,针对掌子面突水涌碴、开挖面坍塌,采取架设临时仰拱和临时挡墙措施,加固绕避;针对初期支护大变形、二次衬砌开裂等情况,采取超前注浆、超前大管棚和双层初期支护等措施,确保隧道衬砌结构安全;针对隧道地下水发育情况,采用排水型防水板、边墙增设碎石盲沟并增加泄水洞等措施,确保隧道运营安全。

  1. Tunneling in high-K isomeric decays

    CERN Document Server

    Shizuma, T; Shimizu, Y R

    2002-01-01

    We have systematically investigated highly-K-forbidden transitions observed in the Hf, W and Os region, using the gamma-tunneling model in which low-K and high-k states interact through a process of quantum tunneling. The measured hindrance factors are compared with the values calculated using the gamma-tunneling model. Isotope dependences of gamma-tunneling probabilities particularly for neutron-rich nuclei and the relation to stimulated decays of isomers are discussed. (author)

  2. Drill and blast tunnelling; Konvensjonell drift av tunneler

    Energy Technology Data Exchange (ETDEWEB)

    Roenn, Paal-Egil

    1997-12-31

    This thesis treats drill and blast tunnelling. The rapid technological advance necessitates revised and updated design criteria, quality requirements and quality control. In situ blast experiments were carried out in order to test new methods and improve the basis for calculation and design. The main topics of the experiments were (1) longer rounds and increased drillhole diameter, (2) emulsion slurry as explosives in tunnelling, and (3) electronic detonators in contour blasting. The experiments show that it is technically feasible to blast rounds of up to 8.6 m length. Using current technology, the economical optimum round length is substantially shorter. Dust, low visibility, noise and toxic fumes are occupational environmental strains for the tunnel workers. Several of the environmental factors are strongly influenced by the type of explosives used. For example, emulsion slurry resulted in 4 to 5 times better visibility than Anolit and the concentration of respirable dust and total dust was reduced by 30-50 %. Electronic detonators were tested and found to give a higher percentage of remaining drillholes in the contour than Nonel detonators. The thesis includes a chapter on economic design of hydropower tunnels. 42 refs., 83 figs., 45 tabs.

  3. Fiber coupled ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1997-01-01

    We report on a scanning tunneling microscope with a photoconductive gate in the tunneling current circuit. The tunneling tip is attached to a coplanar transmission line with an integrated photoconductive switch. The switch is illuminated through a fiber which is rigidly attached to the switch...

  4. Tunnel Face Stability & New CPT Applications

    NARCIS (Netherlands)

    Broere, W.

    2001-01-01

    Nearly all tunnels bored in soft soils have encountered problems with the stability of the tunnel face. In several cases these problems led to an extended stand-still of the boring process. A better understanding of the face stability, and of the soil conditions around the tunnel boring machine, can

  5. A Wind Tunnel Captive Aircraft Testing Technique

    Science.gov (United States)

    1976-04-01

    Flight/Wind Tunnel Correlation of Aircraft Longitudinal Motion ....................................... 14 10. Fright/Wind Tunnel Correlation of...I 2 3 4 5 6 T IME, s e c Figure 9. Flight/wind tunnel correla- tion of aircraft longitudinal motion. ’ D A n ~ v i i i | ~ 0 0 - 4 0

  6. Femtosecond tunneling response of surface plasmon polaritons

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Ha, Taekjip; Jensen, Jacob Riis

    1998-01-01

    We obtain femtosecond (200 fs) time resolution using a scanning tunneling microscope on surface plasmon polaritons (SPPs) generated by two 100 fs laser beams in total internal reflection geometry. The tunneling gap dependence of the signal clearly indicates the tunneling origin of the signal...

  7. The road safety of motorway tunnels.

    NARCIS (Netherlands)

    2009-01-01

    This fact sheet discusses the safety of motorway tunnels in the Netherlands. Broadly speaking, it is not certain whether crashes in the Netherlands are relatively more frequent in tunnels than on open road stretches. However, there are certain factors that increase the risk in tunnels, such as the p

  8. Geochemistry studies pertaining to the G-tunnel radionuclide migration field experiment

    Energy Technology Data Exchange (ETDEWEB)

    Norris, A.E.; Aguilar, R.D.; Bayhurst, B.P.

    1982-11-01

    This report presents the results of geochemical studies of Tunnel Bed tuff that were performed by Los Alamos National Laboratory or done at its direction as part of the Nevada Test Site G-Tunnel Radionuclide Migration Field Experiment. A tuff-treated water was prepared and used in laboratory-scale measurements of radionuclide sorption onto crushed Tunnel Bed tuff, pulverized fracture-fill material, tuff wafers, and a solid tuff core. Modelling studies were undertaken to determine the effects of matrix diffusion and unsaturated tuff on the proposed fracture-flow experiments. The initial results of those studies are presented in this report.

  9. Time tunnels meet warped passages

    CERN Multimedia

    Kushner, David

    2006-01-01

    "Just in time for its 40th anniversary, the classic sci-fi television show "The time tunnel" is out on DVD. The conceit is something every engineer can relate to: a pulled plug. Scientists in an underground lab are working on a secret government experiment in time travel. (1 page)

  10. Tunnel lighting in Europe (abridged).

    NARCIS (Netherlands)

    Schreuder, D.A.

    1972-01-01

    A set of principles embodied in 1971 recommendations of the cie (commission internationale de l'eclairage - international commission on lighting) is beginning to be generally accepted throughout europe, so that it is now possible to speak of a european system of tunnel lighting." the recommendations

  11. The recurrent carpal tunnel syndrome.

    Science.gov (United States)

    Kern, B C; Brock, M; Rudolph, K H; Logemann, H

    1993-01-01

    Sixteen out of 720 patients with carpal tunnel syndrome who had undergone surgery since 1979 were reoperated for a "recurrence" (2.2%). Twelve of these patients had been originally operated on in our department. Thus, our own recurrence rate is 1.7%. Three patients deteriorated following surgery, 6 had an unsatisfactory improvement, and in 7 the symptoms recurred after initial improvement. Eight of the reoperated patients had a predisposing disease (terminal renal insufficiency, insulin-dependent diabetes mellitus, acromegaly). In 10 of the 16 cases the initial operation had been carried out by surgeons in the first three years of training. Reoperation revealed incomplete splitting of the transverse carpal ligament in 10 cases, compression of the median nerve by the scar in 4, injury of the muscular branch in 1, and an anatomical variant as cause of incomplete decompression in 1 patient. "Recurrences" after carpal tunnel surgery are predominantly due to inadequacies of the first procedure. A remarkable number of patients (50%) has predisposing diseases. Interfascicular or epineural neurolysis and complete exposure and neurolysis of the median nerve and its branches is necessary only in cases of recurrence. Their omission at the first surgery does not result in an increased recurrence rate. Our observations indicate that the number of operations for recurrent carpal tunnel syndrome can probably be reduced when the first operation is performed with care and experience. Patients with carpal tunnel syndrome secondary to a systemic disease are particularly at risk.

  12. Introduction to scanning tunneling microscopy

    CERN Document Server

    Chen, C Julian

    2008-01-01

    The scanning tunneling and the atomic force microscope, both capable of imaging individual atoms, were crowned with the Physics Nobel Prize in 1986, and are the cornerstones of nanotechnology today. This is a thoroughly updated version of this 'bible' in the field.

  13. A Seamless Ubiquitous Telehealthcare Tunnel

    Directory of Open Access Journals (Sweden)

    Sao-Jie Chen

    2013-08-01

    Full Text Available Mobile handheld devices are rapidly using to implement healthcare services around the World. Fundamentally, these services utilize telemedicine technologies. A disconnection of a mobile telemedicine system usually results in an interruption, which is embarrassing, and reconnection is necessary during the communication session. In this study, the Stream Control Transmission Protocol (SCTP is adopted to build a stable session tunnel to guarantee seamless switching among heterogeneous wireless communication standards, such as Wi-Fi and 3G. This arrangement means that the telemedicine devices will not be limited by a fixed wireless connection and can switch to a better wireless channel if necessary. The tunnel can transmit plain text, binary data, and video streams. According to the evaluation of the proposed software-based SCTP-Tunnel middleware shown, the performance is lower than anticipated and is slightly slower than a fixed connection. However, the transmission throughput is still acceptable for healthcare professionals in a healthcare enterprise or home care site. It is necessary to build more heterogeneous wireless protocols into the proposed tunnel-switching scheme to support all possible communication protocols. In addition, SCTP is another good choice for promoting communication in telemedicine and healthcare fields.

  14. Tunneling in the SIS Structure

    Science.gov (United States)

    Shukrinov, Yu.; Kohandel, M.

    2000-09-01

    We discuss the effects caused by the layered structure of high temperature superconductors (HTS). We use the layered S-N model to obtain the tunneling current of the SIS structure. The current-voltage characteristic is calculated in the limit cases when dI/dV is proportional to the state density of HTS.

  15. Installation in the SPS tunnel

    CERN Multimedia

    1974-01-01

    The SPS tunnel is 6910 m in circumference and has a cross section of 4 m inner diameter. It is situated at an elevation of 400 m above sea level at a depth below the surface varying between 23 and 65 m. Its walls are lined with a concrete shell of about 30 cm thickness. See also 7410043X

  16. Travelling inside the SPS tunnel

    CERN Multimedia

    1974-01-01

    The golf cart proved to be a very useful form of transport around the 7 km circumference of the machine. It could carry four passengers and pull light equipment in its trailer. Here Peter Zettwoch is the driver along a mock-up tunnel for installation tests. (see photo 7401011X and Photo Archive 7401018)

  17. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  18. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  19. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Shchukin, A. V.

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc bias...

  20. Inelastic scattering in resonant tunneling

    DEFF Research Database (Denmark)

    Wingreen, Ned S.; Jacobsen, Karsten Wedel; Wilkins, John W.

    1989-01-01

    The exact resonant-tunneling transmission probability for an electron interacting with phonons is presented in the limit that the elastic coupling to the leads is independent of energy. The phonons produce transmission sidebands but do not affect the integrated transmission probability or the esc...

  1. NASA Glenn Icing Research Tunnel: Upgrade and Cloud Calibration

    Science.gov (United States)

    VanZante, Judith Foss; Ide, Robert F.; Steen, Laura E.

    2012-01-01

    In 2011, NASA Glenn s Icing Research Tunnel underwent a major modification to it s refrigeration plant and heat exchanger. This paper presents the results of the subsequent full cloud calibration. Details of the calibration procedure and results are presented herein. The steps include developing a nozzle transfer map, establishing a uniform cloud, conducting a drop sizing calibration and finally a liquid water content calibration. The goal of the calibration is to develop a uniform cloud, and to build a transfer map from the inputs of air speed, spray bar atomizing air pressure and water pressure to the output of median volumetric droplet diameter and liquid water content.

  2. Tunnel widening in anterior cruciate ligament reconstruction

    DEFF Research Database (Denmark)

    Clatworthy, M G; Annear, P; Bulow, J U

    1999-01-01

    .1% in the patella tendon group (P = film measurements. Tunnel widening did not correlate with the clinical findings, knee scores, KT-1000 or isokinetic muscle strength. Tunnel widening is marked in the hamstring group. Tunnel widening does not correlate with instability......We report a prospective series evaluating the incidence and degree of tunnel widening in a well-matched series of patients receiving a hamstring or patella tendon graft for anterior cruciate ligament (ACL) deficiency. We correlated tunnel widening with clinical factors, knee scores, KT-1000...

  3. An Entropic Formulation of Tunneling Time

    CERN Document Server

    Demir, Durmus A

    2015-01-01

    Quantum tunneling governs numerous phenomena in biology, chemistry, physics and technology. Tunneling time, formulated in various different forms due to the absence of a time operator in quantum theory, has been measured recently in experiments based on the attoclock in ultrafast laser ionization of Helium atoms [A.~Landsman {\\it et al.}, Optica {\\bf 1}, 343 (2014)]. The experiment performs a refined measurement with which no tunneling time formula in the literature exhibits adequate congruence. Here we show that, entropic considerations lead to a real tunneling time which shows remarkable agreement with the experimental data and stays always subluminal. Indeed, with phase space volume setting the number of microstates for a single evanescing particle in a state of definite momentum consistent with energy conservation, one is naturally led to a statistical description for quantum tunneling in which thermal energy sets the tunneling time. This entropic tunneling time is rather general and might also be extende...

  4. Tunneling Flight Time, Chemistry, and Special Relativity.

    Science.gov (United States)

    Petersen, Jakob; Pollak, Eli

    2017-08-15

    Attosecond ionization experiments have not resolved the question "What is the tunneling time?". Different definitions of tunneling time lead to different results. Second, a zero tunneling time for a material particle suggests that the nonrelativistic theory includes speeds greater than the speed of light. Chemical reactions, occurring via tunneling, should then not be considered in terms of a nonrelativistic quantum theory calling into question quantum dynamics computations on tunneling reactions. To answer these questions, we define a new experimentally measurable paradigm, the tunneling flight time, and show that it vanishes for scattering through an Eckart or a square barrier, irrespective of barrier length or height, generalizing the Hartman effect. We explain why this result does not lead to experimental measurement of speeds greater than the speed of light. We show that this tunneling is an incoherent process by comparing a classical Wigner theory with exact quantum mechanical computations.

  5. NO PLIF Imaging in the CUBRC 48-inch Shock Tunnel

    Science.gov (United States)

    2012-01-01

    II Hypersonic Shock Tunnels, including measurement of temperature and velocity by water vapor-based diode laser absorption (Wehe et al. 1988); NO... GASP code from Aerosoft. Inc (2000). Although the actual experiment is highly unsteady, the steady state Reynolds-averaged Na’Yier-Stokes (RANS...turbulence model implementation in the GASP code. To simulate the effects of finite sheet thickness, the computations shown in Fig. 9 (bottom) are

  6. Measures for the reduction of sinter formations in tunnels

    Science.gov (United States)

    Harer, Gerhard

    2017-09-01

    A considerable part of the maintenance costs of tunnel structures is related to the inspection, maintenance and repair of the drainage system. The drainage system of tunnels is frequently clogged with Calcium precipitates. Cleaning and water conditioning are costintensive for operating companies. Apart from the direct costs associated with inspection, maintenance and repair works of the drainage system indirect costs are generated, such as by the blocking of the tunnel while inspection, maintenance or repair or by the reduction of the permitted operation speed. Sintering and clogging of the drainage systems is mainly caused by dissolution of cement minerals in concrete and mortar and/or by inadequate design and construction of the drainage system and/or grubby workmanship. With long-term studies and in-situ experiments in Austria traffic tunnels the specific input factors for sinter mechanism have been identified and appropriate counter measures could be defined. In particular modified mix designs for shotcretes and mortars have proven to bring a significant beneficial effect. By means of constructional measures and by the application of hardness stabilizers a further reduction of hard deposits inside the drainage system is achievable. The paper will deal with the specific aspects and will propose adequate counter measures.

  7. MANAGEMENT OF TUNNELS ON THE ZAGREB – MACELJ MOTORWAY IN THE COURSE OF TUNNELS EXPLOITATION

    Directory of Open Access Journals (Sweden)

    Zvonimir Deković

    2012-12-01

    Full Text Available he paper focuses on the features of management of tunnels on the Zagreb-Macelj motorway. Management of tunnels is represented trough public-private partnership model that is applied on the Zagreb-Macelj motorway. In the course of tunnel operation and maintenance in the first five years of tunnels exploitation, the emphasis is put on the maintenance of the tunnel equipment systems. Tunnels as part of the motorway alignment are the most demanding facilities for maintaining appropriate safety and operational level in order to rich continuous availability providing safe and quality of service to the motorway users. The goal of the tunnel operation and maintenance is to ensure undisturbed and safe traffic flow through the tunnels by keeping the tunnel at the normal functional conditions.

  8. In-Tunnel Blast Pressure Empirical Formulas for Detonations External, Internal and at the Tunnel Entrance

    Institute of Scientific and Technical Information of China (English)

    LI Xiudi; ZHENG Yingren

    2006-01-01

    In order to define the loading on protective doors of an underground tunnel,the exact knowledge of the blast propagation through tunnels is needed.Thirty-three scale high-explosive tests are conducted to obtain in-tunnel blast pressure for detonations external,internal and at the tunnel entrance.The cross section of the concrete model tunnel is 0.67 m2.Explosive charges of TNT,ranging in mass from 400 g to 4 600 g,are detonated at various positions along the central axis of the model tunnel.Blast gages are flush-installed in the interior surface of the tunnel to record side-on blast pressure as it propagates down the tunnel.The engineering empirical formulas for predicting blast peak pressure are evaluated,and are found to be reasonably accurate for in-tunnel pressure prediction.

  9. Resonant tunnel magnetoresistance in a double magnetic tunnel junction

    KAUST Repository

    Useinov, Arthur

    2011-08-09

    We present quasi-classical approach to calculate a spin-dependent current and tunnel magnetoresistance (TMR) in double magnetic tunnel junctions (DMTJ) FML/I/FMW/I/FMR, where the magnetization of the middle ferromagnetic metal layer FMW can be aligned parallel or antiparallel with respect to the fixed magnetizations of the left FML and right FMR ferromagnetic electrodes. The transmission coefficients for components of the spin-dependent current, and TMR are calculated as a function of the applied voltage. As a result, we found a high resonant TMR. Thus, DMTJ can serve as highly effective magnetic nanosensor for biological applications, or as magnetic memory cells by switching the magnetization of the inner ferromagnetic layer FMW.© Springer Science+Business Media, LLC 2011.

  10. The use of wind tunnel facilities to estimate hydrodynamic data

    Science.gov (United States)

    Hoffmann, Kristoffer; Tophøj Rasmussen, Johannes; Hansen, Svend Ole; Reiso, Marit; Isaksen, Bjørn; Egeberg Aasland, Tale

    2016-03-01

    Experimental laboratory testing of vortex-induced structural oscillations in flowing water is an expensive and time-consuming procedure, and the testing of high Reynolds number flow regimes is complicated due to the requirement of either a large-scale or high-speed facility. In most cases, Reynolds number scaling effects are unavoidable, and these uncertainties have to be accounted for, usually by means of empirical rules-of-thumb. Instead of performing traditional hydrodynamic measurements, wind tunnel testing in an appropriately designed experimental setup may provide an alternative and much simpler and cheaper framework for estimating the structural behavior under water current and wave loading. Furthermore, the fluid velocities that can be obtained in a wind tunnel are substantially higher than in a water testing facility, thus decreasing the uncertainty from scaling effects. In a series of measurements, wind tunnel testing has been used to investigate the static response characteristics of a circular and a rectangular section model. Motivated by the wish to estimate the vortex-induced in-line vibration characteristics of a neutrally buoyant submerged marine structure, additional measurements on extremely lightweight, helium-filled circular section models were conducted in a dynamic setup. During the experiment campaign, the mass of the model was varied in order to investigate how the mass ratio influences the vibration amplitude. The results show good agreement with both aerodynamic and hydrodynamic experimental results documented in the literature.

  11. Water

    Science.gov (United States)

    Leopold, Luna Bergere; Baldwin, Helene L.

    1962-01-01

    What do you use water for?If someone asked you this question you would probably think right away of water for drinking. Then you would think of water for bathing, brushing teeth, flushing the toilet. Your list would get longer as you thought of water for cooking, washing the dishes, running the garbage grinder. Water for lawn watering, for play pools, for swimming pools, for washing the car and the dog. Water for washing machines and for air conditioning. You can hardly do without water for fun and pleasure—water for swimming, boating, fishing, water-skiing, and skin diving. In school or the public library, you need water to wash your hands, or to have a drink. If your home or school bursts into flames, quantities of water are needed to put it out.In fact, life to Americans is unthinkable without large supplies of fresh, clean water. If you give the matter a little thought, you will realize that people in many countries, even in our own, may suffer from disease and dirt simply because their homes are not equipped with running water. Imagine your own town if for some reason - an explosion, perhaps - water service were cut off for a week or several weeks. You would have to drive or walk to a neighboring town and bring water back in pails. Certainly if people had to carry water themselves they might not be inclined to bathe very often; washing clothes would be a real chore.Nothing can live without water. The earth is covered by water over three-fourths of its surface - water as a liquid in rivers, lakes and oceans, and water as ice and snow on the tops of high mountains and in the polar regions. Only one-quarter of our bodies is bone and muscle; the other three-fourths is made of water. We need water to live, and so do plants and animals. People and animals can live a long time without food, but without water they die in a few days. Without water, everything would die, and the world would turn into a huge desert.

  12. Wildlife Tunnel Enhances Population Viability

    Directory of Open Access Journals (Sweden)

    Rodney van der Ree

    2009-12-01

    Full Text Available Roads and traffic are pervasive components of landscapes throughout the world: they cause wildlife mortality, disrupt animal movements, and increase the risk of extinction. Expensive engineering solutions, such as overpasses and tunnels, are increasingly being adopted to mitigate these effects. Although some species readily use such structures, their success in preventing population extinction remains unknown. Here, we use population viability modeling to assess the effectiveness of tunnels for the endangered Mountain Pygmy-possum (Burramys parvus in Australia. The underpasses reduced, but did not completely remove, the negative effects of a road. The expected minimum population size of a "reconnected" population remained 15% lower than that of a comparable "undivided" population. We propose that the extent to which the risk of extinction decreases should be adopted as a measure of effectiveness of mitigation measures and that the use of population modeling become routine in these evaluations.

  13. Seismic scanning tunneling macroscope - Theory

    KAUST Repository

    Schuster, Gerard T.

    2012-09-01

    We propose a seismic scanning tunneling macroscope (SSTM) that can detect the presence of sub-wavelength scatterers in the near-field of either the source or the receivers. Analytic formulas for the time reverse mirror (TRM) profile associated with a single scatterer model show that the spatial resolution limit to be, unlike the Abbe limit of λ/2, independent of wavelength and linearly proportional to the source-scatterer separation as long as the point scatterer is in the near-field region; if the sub-wavelength scatterer is a spherical impedance discontinuity then the resolution will also be limited by the radius of the sphere. Therefore, superresolution imaging can be achieved as the scatterer approaches the source. This is analogous to an optical scanning tunneling microscope that has sub-wavelength resolution. Scaled to seismic frequencies, it is theoretically possible to extract 100 Hz information from 20 Hz data by imaging of near-field seismic energy.

  14. Single-contact tunneling thermometry

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro

    2016-02-23

    A single-contact tunneling thermometry circuit includes a tunnel junction formed between two objects. Junction temperature gradient information is determined based on a mathematical relationship between a target alternating voltage applied across the junction and the junction temperature gradient. Total voltage measured across the junction indicates the magnitude of the target alternating voltage. A thermal gradient is induced across the junction. A reference thermovoltage is measured when zero alternating voltage is applied across the junction. An increasing alternating voltage is applied while measuring a thermovoltage component and a DC rectification voltage component created by the applied alternating voltage. The target alternating voltage is reached when the thermovoltage is nullified or doubled by the DC rectification voltage depending on the sign of the reference thermovoltage. Thermoelectric current and current measurements may be utilized in place of the thermovoltage and voltage measurements. The system may be automated with a feedback loop.

  15. Tunneling magnetoresistance in Si nanowires

    Science.gov (United States)

    Montes, E.; Rungger, I.; Sanvito, S.; Schwingenschlögl, U.

    2016-11-01

    We investigate the tunneling magnetoresistance of small diameter semiconducting Si nanowires attached to ferromagnetic Fe electrodes, using first principles density functional theory combined with the non-equilibrium Green’s functions method for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we systematically study the spin transport properties for neutral nanowires and both n and p doping conditions. We find a substantial low bias magnetoresistance for the neutral case, which halves for an applied voltage of about 0.35 V and persists up to 1 V. Doping in general decreases the magnetoresistance, as soon as the conductance is no longer dominated by tunneling.

  16. Tunneling magnetoresistance in Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    2016-11-09

    We investigate the tunneling magnetoresistance of small diameter semiconducting Si nanowires attached to ferromagnetic Fe electrodes, using first principles density functional theory combined with the non-equilibrium Green\\'s functions method for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we systematically study the spin transport properties for neutral nanowires and both n and p doping conditions. We find a substantial low bias magnetoresistance for the neutral case, which halves for an applied voltage of about 0.35 V and persists up to 1 V. Doping in general decreases the magnetoresistance, as soon as the conductance is no longer dominated by tunneling.

  17. 高海拔隧道涌突水预测分析--以四川小卡子隧道为例%Prediction and Analysis on Water Inrush of High Altitude---Tunnel an example of Xiaokazi Tunnel in Sichuan

    Institute of Scientific and Technical Information of China (English)

    陈欢; 陈亚峰; 谢世杰

    2014-01-01

    The Xiaokazi Tunnel is a portable road to connect Jiulong and Shimian Counties.It is green protection to con-nectS215 andS211.Thealtitudeisabove4000mbetweenJiulongandShimian.AtJiulongcountysurroundingsistheplat-eau dale and upland region and the terrain is undulating seriously.For the growth of the poor geology and special drape structure from Jiulong to the surroundings,the damage caused by ice and snow occur almost every year and influence the line for a long time.The other geological disasters are frequent outbreaks which causing traffic accidents occur frequently,as a constraint to the development of Jiulong County.And thus an urgent requirement on line transformation,it proposed to build a Xiaoka tunnel to connect Jiulong County and Shimian counties,so it calls the highway reconstruction project.%小卡子隧道是连接九龙县城和石棉县城的一条便利通道,它是连接 S215和 S211的绿色保障,九龙和石棉之间是海拔高度4000 m 以上,九龙县城周边为高原宽谷丘陵地区,地势起伏较大。九龙至周边沿线不良地质和特殊褶皱构造发育,其中冰雪害几乎每年冬春都发生,且影响线路较长,其它地质灾害也时常暴发,致使交通事故频繁发生,成为制约九龙县发展,因而急需要对线路进行改造,拟建连接九龙县至石棉县小卡子隧道即为公路改建工程。

  18. Dissipative Effect and Tunneling Time

    Directory of Open Access Journals (Sweden)

    Samyadeb Bhattacharya

    2011-01-01

    Full Text Available The quantum Langevin equation has been studied for dissipative system using the approach of Ford et al. Here, we have considered the inverted harmonic oscillator potential and calculated the effect of dissipation on tunneling time, group delay, and the self-interference term. A critical value of the friction coefficient has been determined for which the self-interference term vanishes. This approach sheds new light on understanding the ion transport at nanoscale.

  19. AUTONOMOUS ROBOTIC INSPECTION IN TUNNELS

    OpenAIRE

    E. Protopapadakis; Stentoumis, C.; Doulamis, N.; A. Doulamis; Loupos, K.; Makantasis, K.; Kopsiaftis, G.; Amditis, A.

    2016-01-01

    In this paper, an automatic robotic inspector for tunnel assessment is presented. The proposed platform is able to autonomously navigate within the civil infrastructures, grab stereo images and process/analyse them, in order to identify defect types. At first, there is the crack detection via deep learning approaches. Then, a detailed 3D model of the cracked area is created, utilizing photogrammetric methods. Finally, a laser profiling of the tunnel’s lining, for a narrow region clos...

  20. Variable density turbulence tunnel facility

    Science.gov (United States)

    Bodenschatz, E.; Bewley, G. P.; Nobach, H.; Sinhuber, M.; Xu, H.

    2014-09-01

    The Variable Density Turbulence Tunnel at the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany, produces very high turbulence levels at moderate flow velocities, low power consumption, and adjustable kinematic viscosity between 10-4 m2/s and 10-7 m2/s. The Reynolds number can be varied by changing the pressure or flow rate of the gas or by using different non-flammable gases including air. The highest kinematic viscosities, and hence lowest Reynolds numbers, are reached with air or nitrogen at 0.1 bar. To reach the highest Reynolds numbers the tunnel is pressurized to 15 bars with the dense gas sulfur hexafluoride (SF6). Turbulence is generated at the upstream ends of two measurement sections with grids, and the evolution of this turbulence is observed as it moves down the length of the sections. We describe the instrumentation presently in operation, which consists of the tunnel itself, classical grid turbulence generators, and state-of-the-art nano-fabricated hot-wire anemometers provided by Princeton University [M. Vallikivi, M. Hultmark, S. C. C. Bailey, and A. J. Smits, Exp. Fluids 51, 1521 (2011)]. We report measurements of the characteristic scales of the flow and of turbulent spectra up to Taylor Reynolds number Rλ ≈ 1600, higher than any other grid-turbulence experiment. We also describe instrumentation under development, which includes an active grid and a Lagrangian particle tracking system that moves down the length of the tunnel with the mean flow. In this configuration, the properties of the turbulence are adjustable and its structure is resolvable up to Rλ ≈ 8000.

  1. Apparent tunneling in chemical reactions

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Hansen, Flemming Yssing; Billing, G. D.

    2000-01-01

    A necessary condition for tunneling in a chemical reaction is that the probability of crossing a barrier is non-zero, when the energy of the reactants is below the potential energy of the barrier. Due to the non-classical nature (i.e, momentum uncertainty) of vibrational states this is, however, ...... to the high momentum tail of the initial vibrational state of nitrogen, allowing for amplitude to cross over the barrier. (C) 2000 Elsevier Science B.V. All rights reserved....

  2. Electrodiagnosis of carpal tunnel syndrome.

    Science.gov (United States)

    Wang, Leilei

    2013-02-01

    This article discusses the historical aspects related to the understanding of carpal tunnel syndrome (CTS) and its diagnosis, highlighting observations about this disease that have yet to be challenged. This is followed by a discussion regarding the use of electrodiagnostic testing as a diagnostic tool for CTS, as well as the author's approach to making the diagnosis of CTS. Finally, conclusions about future directions in the diagnosis and treatment of this disorder are presented.

  3. Digging the CNGS decay tunnel

    CERN Multimedia

    Patrice Loiez

    2002-01-01

    Products of the collision between a proton beam and a graphite target will pass through a horn containing an electric field that will produce a focused beam. These particles will decay into muon neutrinos within the tunnel that is being constructed in these images. The neutrinos will then travel 730 km to Gran Sasso in Italy where huge detectors will observe the beam to study a process called neutrino oscillation.

  4. Water

    Science.gov (United States)

    ... Lead Poisoning Prevention Training Center (HHLPPTC) Training Tracks Water Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir For information about lead in water in Flint, MI, please visit http://www.phe. ...

  5. Autonomous Robotic Inspection in Tunnels

    Science.gov (United States)

    Protopapadakis, E.; Stentoumis, C.; Doulamis, N.; Doulamis, A.; Loupos, K.; Makantasis, K.; Kopsiaftis, G.; Amditis, A.

    2016-06-01

    In this paper, an automatic robotic inspector for tunnel assessment is presented. The proposed platform is able to autonomously navigate within the civil infrastructures, grab stereo images and process/analyse them, in order to identify defect types. At first, there is the crack detection via deep learning approaches. Then, a detailed 3D model of the cracked area is created, utilizing photogrammetric methods. Finally, a laser profiling of the tunnel's lining, for a narrow region close to detected crack is performed; allowing for the deduction of potential deformations. The robotic platform consists of an autonomous mobile vehicle; a crane arm, guided by the computer vision-based crack detector, carrying ultrasound sensors, the stereo cameras and the laser scanner. Visual inspection is based on convolutional neural networks, which support the creation of high-level discriminative features for complex non-linear pattern classification. Then, real-time 3D information is accurately calculated and the crack position and orientation is passed to the robotic platform. The entire system has been evaluated in railway and road tunnels, i.e. in Egnatia Highway and London underground infrastructure.

  6. Quantum Tunneling Affects Engine Performance.

    Science.gov (United States)

    Som, Sibendu; Liu, Wei; Zhou, Dingyu D Y; Magnotti, Gina M; Sivaramakrishnan, Raghu; Longman, Douglas E; Skodje, Rex T; Davis, Michael J

    2013-06-20

    We study the role of individual reaction rates on engine performance, with an emphasis on the contribution of quantum tunneling. It is demonstrated that the effect of quantum tunneling corrections for the reaction HO2 + HO2 = H2O2 + O2 can have a noticeable impact on the performance of a high-fidelity model of a compression-ignition (e.g., diesel) engine, and that an accurate prediction of ignition delay time for the engine model requires an accurate estimation of the tunneling correction for this reaction. The three-dimensional model includes detailed descriptions of the chemistry of a surrogate for a biodiesel fuel, as well as all the features of the engine, such as the liquid fuel spray and turbulence. This study is part of a larger investigation of how the features of the dynamics and potential energy surfaces of key reactions, as well as their reaction rate uncertainties, affect engine performance, and results in these directions are also presented here.

  7. Pharmacotherapy of carpal tunnel syndrome.

    Science.gov (United States)

    de Pablo, Paola; Katz, Jeffrey N

    2003-06-01

    Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome. CTS is a compression neuropathy caused by elevated pressure in the carpal tunnel. CTS has the potential to substantially limit performance of activities of daily living for some individuals. The goal of therapy for CTS is to improve symptoms and reduce signs of the disease, as well as prevent progression and loss of hand function. There are several treatment alternatives to relieve the pressure on the median nerve, both surgical and conservative. The most common measures employed in the initial treatment of CTS are NSAIDs, local and systemic corticosteroids, diuretics and pyridoxine. However, CTS treatment usually includes a combination of pharmacotherapy with other strategies such as splinting and activity modification. Injections of corticosteroids into the carpal tunnel are often employed for cases not responding to conservative treatment. Surgery is superior to conservative therapies for most persistently symptomatic patients. The aim of this paper is to review the pharmacological agents used for relieving the symptoms of CTS.

  8. Confocal Annular Josephson Tunnel Junctions

    Science.gov (United States)

    Monaco, Roberto

    2016-09-01

    The physics of Josephson tunnel junctions drastically depends on their geometrical configurations and here we show that also tiny geometrical details play a determinant role. More specifically, we develop the theory of short and long annular Josephson tunnel junctions delimited by two confocal ellipses. The behavior of a circular annular Josephson tunnel junction is then seen to be simply a special case of the above result. For junctions having a normalized perimeter less than one, the threshold curves in the presence of an in-plane magnetic field of arbitrary orientations are derived and computed even in the case with trapped Josephson vortices. For longer junctions, a numerical analysis is carried out after the derivation of the appropriate motion equation for the Josephson phase. We found that the system is modeled by a modified and perturbed sine-Gordon equation with a space-dependent effective Josephson penetration length inversely proportional to the local junction width. Both the fluxon statics and dynamics are deeply affected by the non-uniform annulus width. Static zero-field multiple-fluxon solutions exist even in the presence of a large bias current. The tangential velocity of a traveling fluxon is not determined by the balance between the driving and drag forces due to the dissipative losses. Furthermore, the fluxon motion is characterized by a strong radial inward acceleration which causes electromagnetic radiation concentrated at the ellipse equatorial points.

  9. Variable Density Turbulence Tunnel Facility

    CERN Document Server

    Bewley, Gregory P; Sinhuber, Michael; Xu, Haitao; Bodenschatz, Eberhard

    2014-01-01

    The Variable Density Turbulence Tunnel (VDTT) at the Max Planck Institute for Dynamics and Self-Organization in G\\"ottingen, Germany produces very high turbulence levels at moderate flow velocities, low power consumption and adjustable kinematic viscosity. To reach the highest Reynolds number, the tunnel can be filled and pressurized up to 15 bar with the dense gas sulfur hexafluoride (SF$_6$). The Reynolds number can be varied by changing the pressure or flow rate of the gas or by using different non-flammable gases including air. Turbulence is generated at the upstream ends of two measurement sections with grids, and the evolution of this turbulence is observed as it moves down the length of the sections. We describe the instrumentation presently in operation, which consists of the tunnel itself, classical grid turbulence generators, and state-of-the-art nano-fabricated hot-wire anemometers provided by Princeton University [Vallikivi et al. (2011) Exp. Fluids 51, 1521]. We report measurements of the charact...

  10. Backfilling of deposition tunnels: Use of bentonite pellets

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, David (Atomic Energy of Canada Limited (Canada)); Sanden, Torbjoern (Clay Technology AB (Sweden)); Jonsson, Esther (Swedish Nuclear Fuel and Waste Mangaement Co. (Sweden)); Hansen, Johanna (Posiva Oy (Finland))

    2011-02-15

    The state of knowledge related to use of bentonite pellets as part of backfill or other gap filling components in repository applications is reviewed. How the pellets interact with adjacent sealing materials and the surrounding rock mass is a critical aspect in determining backfill behaviour. The key features and processes that determine how the pellet component of the KBS-3V deposition tunnel backfill will behave are discussed and recommendations related to what additional information needs to be developed are provided. Experiences related to pellet material composition, size, shape, placement options and more importantly, the density to which they can be placed all indicate that there are significant limitations to the achievable as-placed density of bentonite pellet fill. Low as-placed density of the pellet fill component of the backfill is potentially problematic as the outermost regions of tunnel backfill will be the first region of the backfill to be contacted by water entering the tunnels. It is also through this region that initial water movement along the length of the deposition tunnels will occur. This will greatly influence the operations in a tunnel, especially with respect to situations where water is exiting the downstream face of still open deposition tunnels. Pellet-filled regions are also sensitive to groundwater salinity, susceptible to development of piping features and subsequent mechanical erosion by through flowing water, particularly in the period preceding deposition tunnel closure. A review of the experiences of various organisations considering use of bentonite-pellet materials as part of buffer or backfill barriers is provided in this document. From this information, potential options and limitations to use of pellets or pellet-granule mixtures in backfill are identified. Of particular importance is identification of the apparent upper-limits of dry density to which such materials can to be placed in the field. These bounds will

  11. Essentials of the construction and exploitation of hydraulic tunnels in karst of eastern Herzegovina

    Directory of Open Access Journals (Sweden)

    Golijanin Aleksandar R.

    2016-01-01

    Full Text Available The main problem in the process of construction, and it also proved in practice during exploitation of hydrotechnical tunnels constructed in the karst of eastern Herzegovina, are caverns. Of all the problems that may occur in the process of construction and during exploitation of hydrotechnical tunnels constructed in the Upper Cretaceous limestone rocks, only caverns have the characteristics (size, shape, type of backfill, water inflow which, in extreme cases, represent a problem that is difficult to solve. In such circumstances, the tunnel construction is subject to unpredictable and sometimes devastating impairments. Cavern is a term that represents a wider area within the karst sediments, which can be partially backfilled with debris, sometimes completely empty, connected with the ground surface by karst channels. Accumulation tunnels for power plants, i.e. the tunnels where the water flow is under pressure, are particularly susceptible to these impairments. This study introduces practical problems that have occurred in hydrotechnical tunnels constructed in the hydropower system of Trebišnjica.

  12. Tunneling Dynamics Between Atomic Bright Solitons

    CERN Document Server

    Zhao, Li-Chen; Yang, Zhan-Ying; Yang, Wen-Li

    2016-01-01

    We investigate tunneling behavior between two bright solitons in a Bose-Einstein condensate with attractive contact interactions between atoms. The explicit tunneling properties including tunneling particles and oscillation period are described analytically, which indicates that the periodic tunneling form is a nonlinear Josephson type oscillation. The results suggest that the breathing behavior of solitons comes from the tunneling mechanism in an effective double-well potential, which is quite different from the modulational instability mechanism for Akhmediev breather and K-M breather. Furthermore, we obtain a phase diagram for two soliton interaction which admits tunneling property, particle-like property, interference property, and a resonant interaction case. The explicit conditions for them are clarified based on the defined critical distance $d_c$ and spatial interference period $D$.

  13. Investigation into scanning tunnelling luminescence microscopy

    CERN Document Server

    Manson-Smith, S K

    2001-01-01

    This work reports on the development of a scanning tunnelling luminescence (STL) microscope and its application to the study of Ill-nitride semiconductor materials used in the production of light emitting devices. STL microscopy is a technique which uses the high resolution topographic imaging capabilities of the scanning tunnelling microscope (STM) to generate high resolution luminescence images. The STM tunnelling current acts as a highly localised source of electrons (or holes) which generates luminescence in certain materials. Light generated at the STM tunnelling junction is collected concurrently with the height variation of the tunnelling probe as it is scanned across a sample surface, producing simultaneous topographic and luminescence images. Due to the very localised excitation source, high resolution luminescence images can be obtained. Spectroscopic resolution can be obtained by using filters. Additionally, the variation of luminescence intensity with tunnel current and with bias voltage can provi...

  14. Tunnel design considering stress release effect

    Institute of Scientific and Technical Information of China (English)

    Van-hung DAO

    2009-01-01

    In tunnel design,the determination of installation time and the stiffness of supporting structures is very important to the tunnel stability.This study used the convergence-confinement method to determine the stress and displacement of the tunnel while considering the counter-pressure curve of the ground base,the stress release effect,and the interaction between the tunnel lining and the rock surrounding the tunnel chamber.The results allowed for the determination of the installation time,distribution and strength of supporting structures.This method was applied to the intake tunnel in the Ban Ve Hydroelectric Power Plant,in Nghe An Province,Vietnam.The results show that when a suitable displacement u0 ranging from 0.0865 m to 0.0919 m occurrs,we can install supporting structures that satisfy the stability and economical requirements.

  15. Diffusion-weighted magnetic resonance imaging of the ulnar nerve in cubital tunnel syndrome.

    Science.gov (United States)

    Iba, K; Wada, T; Tamakawa, M; Aoki, M; Yamashita, T

    2010-01-01

    Diffusion-weighted images based on magnetic resonance reveal the microstructure of tissues by monitoring the random movement of water molecules. In this study, we investigated whether this new technique could visualize pathologic lesions on ulnar nerve in cubital tunnel. Six elbows in six healthy males without any symptoms and eleven elbows in ten patients with cubital tunnel syndrome underwent on diffusion-weighted MRI. No signal from the ulnar nerve was detected in normal subjects. Diffusion-weighted MRI revealed positive signals from the ulnar nerve in all of the eleven elbows with cubital tunnel syndrome. In contrast, conventional T2W-MRI revealed high signal intensity in eight elbows and low signal intensity in three elbows. Three elbows with low signal MRI showed normal nerve conduction velocity of the ulnar nerve. Diffusion-weighted MRI appears to be an attractive technique for diagnosis of cubital tunnel syndrome in its early stages which show normal electrophysiological and conventional MRI studies.

  16. RITD – Wind tunnel testing

    Science.gov (United States)

    Haukka, Harri; Harri, Ari-Matti; Aleksashkin, Sergei; Koryanov, Valeri; Schmidt, Walter; Heilimo, Jyri; Finchenko, Valeri; Martynov, Maxim; Ponomarenko, Andrey; Kazakovtsev, Victor; Arruego, Ignazio

    2015-04-01

    An atmospheric re-entry and descent and landing system (EDLS) concept based on inflatable hypersonic decelerator techniques is highly promising for the Earth re-entry missions. We developed such EDLS for the Earth re-entry utilizing a concept that was originally developed for Mars. This EU-funded project is called RITD - Re-entry: Inflatable Technology Development - and it was to assess the bene¬fits of this technology when deploying small payloads from low Earth orbits to the surface of the Earth with modest costs. The principal goal was to assess and develope a preliminary EDLS design for the entire relevant range of aerodynamic regimes expected to be encountered in Earth's atmosphere during entry, descent and landing. The RITD entry and descent system utilizes an inflatable hypersonic decelerator. Development of such system requires a combination of wind tunnel tests and numerical simulations. This included wind tunnel tests both in transsonic and subsonic regimes. The principal aim of the wind tunnel tests was the determination of the RITD damping factors in the Earth atmosphere and recalculation of the results for the case of the vehicle descent in the Mars atmosphere. The RITD mock-up model used in the tests was in scale of 1:15 of the real-size vehicle as the dimensions were (midsection) diameter of 74.2 mm and length of 42 mm. For wind tunnel testing purposes the frontal part of the mock-up model body was manufactured by using a PolyJet 3D printing technology based on the light curing of liquid resin. The tail part of the mock-up model body was manufactured of M1 grade copper. The structure of the mock-up model placed th center of gravity in the same position as that of the real-size RITD. The wind tunnel test program included the defining of the damping factor at seven values of Mach numbers 0.85; 0.95; 1.10; 1.20; 1.25; 1.30 and 1.55 with the angle of attack ranging from 0 degree to 40 degrees with the step of 5 degrees. The damping characteristics of

  17. THE WALL EFFECT ON VENTILATED CAVITATING FLOWS IN CLOSED CAVITATION TUNNELS

    Institute of Scientific and Technical Information of China (English)

    CHEN Xin; LU Chuan-jing; LI Jie; PAN Zhan-cheng

    2008-01-01

    For ventilated cavitating flows in a closed water tunnel, the wall effect may exert an important influence on cavity shape and hydrodynamics. An isotropic mixture multiphase model was established to study the wall effect based on the RANS equations,coupled with a natural cavitation model and the RaNG k-ε turbulent model. The governing equations were discrctized using the finite volume method and solved by the Gauss-Seidel linear equation solver on the basis of a segregation algorithm. The algebraic multigrid approach was carried through to accelerate the convergence of solution. The steady ventilated cavitating flows in water tunnels of different diameter were simulated for a conceptual underwater vehicle model which had a disk cavitator. It is found that the choked cavitation number derived is close to the approximate solution of natural cavitating flow for a 3-D disk. The critical ventilation rate falls with decreasing diameter of the water tunnel. However, the cavity size and drag coefficient are rising with the decrease in tunnel diameter for the same ventilation rate, and the cavity size will be much different in water tunnels of different diameter even for the same ventilated cavitation number.

  18. COMPARISON TRADITIONAL SYSTEMS OF TUNNEL FORMWORK SYSTEM

    OpenAIRE

    ERKAN, İbrahim Hakkı; Yılmaz, Ülkü Sultan; Türken, Hakan

    2011-01-01

    Tunnel formwork systems became the most widespread construction technology preferred in recent years in Turkey due to rapidity and economy. In this study, before all else, a brief information was given about the types and construction techniques of tunnel formwork systems. Then a reinforced concrete building sample was firstly modeled as it was constructed with the tunnel formwork system and secondly modeled as it was formed by a frame system with shear walls constructed by the traditional re...

  19. Quantum tunneling and field electron emission theories

    CERN Document Server

    Liang, Shi-Dong

    2013-01-01

    Quantum tunneling is an essential issue in quantum physics. Especially, the rapid development of nanotechnology in recent years promises a lot of applications in condensed matter physics, surface science and nanodevices, which are growing interests in fundamental issues, computational techniques and potential applications of quantum tunneling. The book involves two relevant topics. One is quantum tunneling theory in condensed matter physics, including the basic concepts and methods, especially for recent developments in mesoscopic physics and computational formulation. The second part is the f

  20. Electromyographic diagnosis of the carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    K. Toyonaga

    1978-06-01

    Full Text Available Sensory conduction velocities of the median nerVe were studied from digit to palm and from palm to wrist in normal subjects and in patients with the carpal tunnel syndrome. Definite slowing was noted in the palm to wrist segment, even in the early carpal tunnel syndrome. It was noted that 37% of normal women over 40 years of age had electrophysiological evidence of the carpal tunnel syndrome.

  1. Low-Frequency Electromagnetic Backscattering from Tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Casey, K; Pao, H

    2007-01-16

    Low-frequency electromagnetic scattering from one or more tunnels in a lossy dielectric half-space is considered. The tunnel radii are assumed small compared to the wavelength of the electromagnetic field in the surrounding medium; a tunnel can thus be modeled as a thin scatterer, described by an equivalent impedance per unit length. We examine the normalized backscattering width for cases in which the air-ground interface is either smooth or rough.

  2. Raynaud's syndrome and carpal tunnel syndrome.

    OpenAIRE

    Waller, D G; Dathan, J R

    1985-01-01

    We report three cases of Raynaud's syndrome with digital ischaemic ulceration, in association with carpal tunnel syndrome. In all cases, the aetiology of the Raynaud's syndrome was probably unrelated to the nerve compression. However, symptoms were worse on the side of the median nerve lesion in two patients and worse on the side with the most severe nerve dysfunction in the third; symptoms were relieved by carpal tunnel decompression in two patients. We suggest that carpal tunnel syndrome ma...

  3. Predictive modelling of ferroelectric tunnel junctions

    Science.gov (United States)

    Velev, Julian P.; Burton, John D.; Zhuravlev, Mikhail Ye; Tsymbal, Evgeny Y.

    2016-05-01

    Ferroelectric tunnel junctions combine the phenomena of quantum-mechanical tunnelling and switchable spontaneous polarisation of a nanometre-thick ferroelectric film into novel device functionality. Switching the ferroelectric barrier polarisation direction produces a sizable change in resistance of the junction—a phenomenon known as the tunnelling electroresistance effect. From a fundamental perspective, ferroelectric tunnel junctions and their version with ferromagnetic electrodes, i.e., multiferroic tunnel junctions, are testbeds for studying the underlying mechanisms of tunnelling electroresistance as well as the interplay between electric and magnetic degrees of freedom and their effect on transport. From a practical perspective, ferroelectric tunnel junctions hold promise for disruptive device applications. In a very short time, they have traversed the path from basic model predictions to prototypes for novel non-volatile ferroelectric random access memories with non-destructive readout. This remarkable progress is to a large extent driven by a productive cycle of predictive modelling and innovative experimental effort. In this review article, we outline the development of the ferroelectric tunnel junction concept and the role of theoretical modelling in guiding experimental work. We discuss a wide range of physical phenomena that control the functional properties of ferroelectric tunnel junctions and summarise the state-of-the-art achievements in the field.

  4. Fire safety assessment of tunnel structures

    DEFF Research Database (Denmark)

    Gkoumas, Konstantinos; Giuliani, Luisa; Petrini, Francesco

    2011-01-01

    durability provisions, commitment to environmental aspects, issues of sustainability and safety assurance, for their whole lifecycle. The design for safety of tunnel infrastructures is a multifaceted process, since there are many aspects that need to be accounted for, regarding different aspects (e...... for upgrading fire safety provisions and tunnel management are also important for existing tunnels. In this study, following a brief introduction of issues regarding the above mentioned aspects, the structural performance of a steel rib for a tunnel infrastructure subject to fire is assessed by means...

  5. Assessment of Scaled Rotors for Wind Tunnel Experiments.

    Energy Technology Data Exchange (ETDEWEB)

    Maniaci, David Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kelley, Christopher Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Chiu, Phillip [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-07-01

    Rotor design and analysis work has been performed to support the conceptualization of a wind tunnel test focused on studying wake dynamics. This wind tunnel test would serve as part of a larger model validation campaign that is part of the Department of Energy Wind and Water Power Program’s Atmosphere to electrons (A2e) initiative. The first phase of this effort was directed towards designing a functionally scaled rotor based on the same design process and target full-scale turbine used for new rotors for the DOE/SNL SWiFT site. The second phase focused on assessing the capabilities of an already available rotor, the G1, designed and built by researchers at the Technical University of München.

  6. An introduction to RAM analysis of EPB tunnel boring machine

    Directory of Open Access Journals (Sweden)

    Hasel Amini Khoshalan

    2014-03-01

    Full Text Available Earth pressure balance tunnel boring machines (EPB - TBMs are favorably used in construction of tunnels in urban areas. These more expensive machines with high operational costs require an exclusive study and knowledge on these machine components and subsystems and their failure and downtimes for time planning, cost control and performance prediction with a high accuracy. Thus guidelines for reliability, availability and maintainability (RAM analysis of an EPB machine are completely expressed. Gathering and recording all daily failure and repair times and other maintenance tasks, dividing the machine into subsystems (including mechanical subsystem, electrical subsystem, hydraulic subsystem, pneumatic subsystem and water subsystem, graphical tests (trend test and correlation test, statistical tests and analysis are discussed in detail.

  7. Abandoned coal mine tunnels: Future heating/power Supply centers

    Institute of Scientific and Technical Information of China (English)

    Luo Pingjia; Chen Ning

    2011-01-01

    We have studied three plans for re-use of the abandoned mine roadway tunnels as an energy center.These are the thermostat plan,the thermal accumulator plan,and the CAES plan.Calculations show that the thermostat plan can provide over 15,000 m2 of building air-conditioning/heating load for each kilometer of roadway,but electric power is needed to run the system.Numerical research proved that the accumulation of hot water in the roadway for seasonal heating purposes (a temperature swing from 90 to 54 ℃) is a viable possibility.The CAES plan proposes using the discarded coal mine tunnel as a peaking power station with an energy storage density over 7000 kJ/m3.It can be concluded that presently abandoned coal mines could be reformed into future energy centers for a city.

  8. Surgical efficacy of carpal tunnel release for carpal tunnel syndrome in acromegaly: report of four patients.

    Science.gov (United States)

    Iwasaki, N; Masuko, T; Ishikawa, J; Minami, A

    2005-12-01

    Although carpal tunnel syndrome is frequent in acromegaly, few acromegalics will be encountered by most hand surgeons. This paper considers the treatment of four cases of acromegaly in whom carpal tunnel syndrome arose, to discuss aspects of management of carpal tunnel syndrome in this patient group.

  9. Tunneling electroresistance of MgZnO-based tunnel junctions

    Science.gov (United States)

    Belmoubarik, Mohamed; Al-Mahdawi, Muftah; Obata, Masao; Yoshikawa, Daiki; Sato, Hideyuki; Nozaki, Tomohiro; Oda, Tatsuki; Sahashi, Masashi

    2016-10-01

    We investigated the tunneling electroresistance (TER) in metal/wurtzite-MgZnO/metal junctions for applications in nonvolatile random-access memories. A resistive switching was detected utilizing an electric-field cooling at ±1 V and exhibited a TER ratio of 360%-490% at 2 K. The extracted change in the average barrier height between the two resistance states gave an estimation of the MgZnO electric polarization at 2.5 μC/cm2 for the low-temperature limit. In addition, the temperature-dependent TER ratio and the shift of the localized states energies at the barrier interface supported the ferroelectric behavior of the MgZnO tunnel-barrier. From the first-principles calculations, we found a similar effect of the barrier height change coming from the reversal of ZnO electric polarization. The possibility of using metal electrodes and lower growth temperatures, in addition to the ferroelectric property, make the ZnO-based memory devices suitable for CMOS integration.

  10. More about tunnelling times and superluminal tunnelling (Hartmann effect)

    Energy Technology Data Exchange (ETDEWEB)

    Olkhovsky, V.S. [Ukrainian Akademy of Sciences, Kiev (Ukraine). Inst. for Nuclear Research]|[INFN-Sezione di Catania (Italy); Recami, E. [Bergamo Univ. (Italy). Facolta` di Ingegneria]|[State Univ. at Campinas, Campinas (Brazil); Raciti, F. [Catania Univ. (Italy); Zaichenko, A. [Ukrainian Akademy of Sciences, Kiev (Ukraine). Inst. for Nuclear Reserch

    1995-05-01

    Aims of the present paper are: (i) presenting and analysing the results of various numerical calculations on the penetration and return times <{tau}{sub Pen}>, <{tau}{sub Ret}>, during tunnelling inside a rectangular potential barrier, for various penetration depths x{sub f}; (ii) putting forth and discussing suitable definitions, besides of the mean values, also of the variances (or dispersions) D{sub {tau}T} and D{sub {tau}R} for the time durations of transmission and reflection processes; (iii) mentioning, moreover, that our definition <{tau}{sub T}> for the average transmission time results to constitute an improvement of the ordinary dwell- time formula; (iv) commenting, at last, on the basis of the new numerical results, upon some recent criticism by C.R. Leavens. The paper stresses that numerical evaluations confirm that the approach implied, and implies, the existence of the Hartmann effect: an effect that in these days (due to the theoretical connections between tunnelling and evanescent-wave propagation) is receiving - at Cologne, Berkeley, Florence and Vienna - indirect, but quite interesting, experimental verification.

  11. Tunneling without barriers with gravity

    CERN Document Server

    Kanno, Sugumi; Soda, Jiro

    2012-01-01

    We consider the vacuum decay of the flat Minkowski space to an anti-de Sitter space. We find a one-parameter family of potentials that allow exact, analytical instanton solutions describing tunneling without barriers in the presence of gravity. In the absence of gravity such instantons were found and discussed by Lee and Weinberg more than a quarter of a century ago. The bounce action is also analytically computed. We discuss possible implications of these new instantons to cosmology in the context of the string theory landscape.

  12. Quantum tunnelling in condensed media

    CERN Document Server

    Kagan, Yu

    1992-01-01

    The essays in this book deal with of the problem of quantum tunnelling and related behavior of a microscopic or macroscopic system, which interacts strongly with an ""environment"" - this being some form of condensed matter. The ""system"" in question need not be physically distinct from its environment, but could, for example, be one particular degree of freedom on which attention is focussed, as in the case of the Josephson junction studied in several of the papers. This general problem has been studied in many hundreds, if not thousands, of articles in the literature, in contexts as diverse

  13. Dynamical tunneling in optical cavities

    CERN Document Server

    Hackenbroich, G; Hackenbroich, Gregor; Noeckel, Jens U.

    1998-01-01

    The lifetime of whispering gallery modes in a dielectric cavity with a metallic inclusion is shown to fluctuate by orders of magnitude when size and location of the inclusion are varied. We ascribe these fluctuations to tunneling transitions between resonances quantized in different regions of phase space. This interpretation is confirmed by a comparison of the classical phase space structure with the Husimi distribution of the resonant modes. A model Hamiltonian is introduced that describes the phenomenon and shows that it can be expected in a more general class of systems.

  14. Full-Scale Tunnel (FST)

    Science.gov (United States)

    1929-01-01

    Modified propeller and spinner in Full-Scale Tunnel (FST) model. On June 26, 1929, Elton W. Miller wrote to George W. Lewis proposing the construction of a model of the full-scale tunnel. 'The excellent energy ratio obtained in the new wind tunnel of the California Institute of Technology suggests that before proceeding with our full scale tunnel design, we ought to investigate the effect on energy ratio of such factors as: 1. small included angle for the exit cone; 2. carefully designed return passages of circular section as far as possible, without sudden changes in cross sections; 3. tightness of walls. It is believed that much useful information can be obtained by building a model of about 1/16 scale, that is, having a closed throat of 2 ft. by 4 ft. The outside dimensions would be about 12 ft. by 25 ft. in plan and the height 4 ft. Two propellers will be required about 28 in. in diameter, each to be driven by direct current motor at a maximum speed of 4500 R.P.M. Provision can be made for altering the length of certain portions, particularly the exit cone, and possibly for the application of boundary layer control in order to effect satisfactory air flow. This model can be constructed in a comparatively short time, using 2 by 4 framing with matched sheathing inside, and where circular sections are desired they can be obtained by nailing sheet metal to wooden ribs, which can be cut on the band saw. It is estimated that three months will be required for the construction and testing of such a model and that the cost will be approximately three thousand dollars, one thousand dollars of which will be for the motors. No suitable location appears to exist in any of our present buildings, and it may be necessary to build it outside and cover it with a roof.' George Lewis responded immediately (June 27) granting the authority to proceed. He urged Langley to expedite construction and to employ extra carpenters if necessary. Funds for the model came from the FST project

  15. Metal-Vacuum-Metal Tunneling

    Science.gov (United States)

    1990-11-01

    the unexposed areas was removed with wet etchants. The Al lines formed in this way were 1000 A in width. The field emission mode was also used by...positioned close to the substrate within tunneling range. Whey they ramped the tip voltage to 10-20 volts they formed patterns on the substrate that were...associated with the light induced decomposition of III-V compounds. It is based on well-known work on photo- oxidation and the anisotropic etching of III-V

  16. Water

    CSIR Research Space (South Africa)

    Van Wyk, Llewellyn V

    2010-08-01

    Full Text Available Water scarcity is without a doubt on of the greatest threats to the human species and has all the potential to destabilise world peace. Falling water tables are a new phenomenon. Up until the development of steam and electric motors, deep groudwater...

  17. Innovative Application of Needle-beam Full-circular Formwork Jumbos in Construction of Lining of Sub-sea Water-diversion Tunnel%针梁式全圆模板台车在海底引水隧洞工程衬砌施工中的创新应用

    Institute of Scientific and Technical Information of China (English)

    陈启伟; 王亚利; 张建

    2013-01-01

    Needle-beam full-circular formwork jumbos are used in the construction of the secondary lining of the intake tunnel of Taishan Nuclear Power Plant,so as to realize once-for-all and rapid construction of the full-circular concrete lining of the sub-sea water-diversion tunnel.In this paper,the method and procedure of the construction of the secondary lining are analyzed,the main structure and technical parameters of the formwork jumbos are presented,and the key construction technologies are described.Furthermore,three innovative points of the application of the formwork jumbos,including the construction arrangement and design inside and outside of the tunnel in the case of 3 formwork jumbos,the continuous construction of the lining by means of 3 formwork jumbos and the cautions for the continuous construction of the lining by 3 formwork jumbos,are summarized.%为了解决海底引水隧洞衬砌混凝土施工全圆一次成型和长距离隧洞衬砌施工短工期内快速完成等诸多问题,选用针梁式全圆模板台车对台山核电站取水隧洞工程进行二次衬砌施工.分析长大隧洞二次衬砌总体施工方法及流程,详细介绍模板台车的构造及主要技术参数,阐述模板台车关键施工工艺和技术.结合工程概况和工期要求,总结了以下3个创新应用结论:在3台模板台车连续跳板作业条件下,隧道内、外的施工布局和流程设计;3台模板台车一次性灌注整体模板连续跳板衬砌施工的工艺和方法;3台模板台车连续跳板流水线作业施工注意事项.

  18. 水下超大断面隧道衬砌施工新技术%New Technology for Construction of Secondary Lining for Under-water Tunnel Sections with Super-large Cross-sections

    Institute of Scientific and Technical Information of China (English)

    黄灵强

    2013-01-01

    The bifurcation sections of Yingpanlu Xiangjian River Crossing Tunnel have super-large cross-sections.The bifurcation sections, located in complex geological conditions, are excavated by double side drift method.The conventional lining construction method can not meet the requirements to ensure the safety of the tunnel construction and the primary support.Therefore, a new lining construction technology, that is, installing the secondary lining by means of special lining formwork jumbos and full scaffold system while keeping the temporary support in place, is adopted.In the paper, the new lining construction technology is presented and the key points of the technology are expounded.The practice demonstrates that the new lining construction technology adopted is effective.%营盘路湘江隧道主线与匝道分合流段均以暗挖形式设计,地质相当复杂,江底分岔大跨段(A、B型)超大断面采用双侧壁导坑法施工.为了保证施工和初期支护的结构安全,在量测数据反映初期支护安全预警的情况下,传统的衬砌施工方法已经不能满足正常施工状态的需求.本文介绍了一种在保留临时支撑的情况下采用特制异型台车和满堂支架组合联合施工拱墙的新型衬砌施工技术,并对关键技术控制进行了详细阐述.实践证明,不拆支撑采用台车和满堂支架组合施工分岔段二次衬砌的方法是切实有效的,同时也为其他类似工程施工提供参考.

  19. E-plastic limit equilibrium analysis on water-bearing rock in deep tunnel based on strain-softening%基于应变软化深埋巷道含水围岩的弹塑性极限平衡分析

    Institute of Scientific and Technical Information of China (English)

    刘树新; 刘长武; 张飞; 曹磊

    2011-01-01

    After excavating tunnel in rock mass, secondary stress presents in the wall rock with water-bearing,because the in-situ rock stress distribution and the infiltrative hydraulic pressure action is disturbed. The unbalanced stress is the major reason of rock mass deformation, displacement and even destroy. Based on Mohr-Coulomb and elastic-plasticity theory and rock damage caused by rock strain-softening, taking circular section of underground deep tunnel as example, the paper calculates and analyses the relationship between plastic range and supporting force in the case of limit equilibrium. The study establishes theoretical foundation for actual underground project construction and support engineering.%在岩体内开挖巷道后,由于干扰了原岩应力分布和渗透水压力的作用,巷道含水围岩中呈现次生应力,这种新出现的不平衡应力是引起岩体产生变形、位移,甚至破坏的主要根源.以圆形截面巷道为例,结合莫尔-库仑理论从围岩弹塑性变形的角度出发,在考虑了围岩应变软化所引起围岩损伤的基础上,计算和分析了地下巷道含水围岩达到极限平衡时围岩塑性区范围与相应支护抗力之间的关系,为实际地下工程施工和支护提供了理论基础.

  20. Computational Wind Tunnel: A Design Tool for Rotorcraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Rotorcraft engineers traditionally use the wind tunnel to evaluate and finalize designs. Insufficient correlation between wind tunnel results and flight tests, have...

  1. Performance characteristics of tunnel boring machine in basalt and pyroclastic rocks of Deccan traps – A case study

    Directory of Open Access Journals (Sweden)

    Prasnna Jain

    2014-02-01

    Full Text Available A 12.24 km long tunnel between Maroshi and Ruparel College is being excavated by tunnel boring machine (TBM to improve the water supply system of Greater Mumbai, India. In this paper, attempt has been made to establish the relationship between various litho-units of Deccan traps, stability of tunnel and TBM performances during the construction of 5.83 km long tunnel between Maroshi and Vakola. The Maroshi–Vakola tunnel passes under the Mumbai Airport and crosses both runways with an overburden cover of around 70 m. The tunneling work was carried out without disturbance to the ground. The rock types encountered during excavation are fine compacted basalt, porphyritic basalt, amygdaloidal basalt, pyroclastic rocks with layers of red boles and intertrappean beds consisting of various types of shales. Relations between rock mass properties, physico-mechanical properties, TBM specifications and the corresponding TBM performance were established. A number of support systems installed in the tunnel during excavation were also discussed. The aim of this paper is to establish, with appropriate accuracy, the nature of subsurface rock mass condition and to study how it will react to or behave during underground excavation by TBM. The experiences gained from this project will increase the ability to cope with unexpected ground conditions during tunneling using TBM.

  2. 100 km under ground. Longest well-known aqueduct tunnel of the antique in Jordan and Syria; 100 km unter Tage. Laengster bisher bekannter Aquaedukttunnel der Antike in Jordanien und Syrien

    Energy Technology Data Exchange (ETDEWEB)

    Doering, Mathias [Technische Univ. Bergakademie Freiberg (Germany). IWTG

    2010-05-15

    Since 2004, the author of the contribution under consideration investigates an ancient tunnel system with unknown extents in the border area between Jordan and Syria. It is a part of a nearly 170 km long Roman aqueduct which supplies three cities with water. The nearly 106 km long, partly plastered tunneling system was built from approximately 2,900 building pits with stairs in open ends tunneling. Not only mallet and iron, but also half-mechanical propulsion equipment were used due to regular cut traces. The aqueduct might be one the most extensive aqueducts in the Roman antiquity. The tunnel might be the longest well-known tunnel from the antiquity.

  3. Transport of dangerous goods through road tunnels

    DEFF Research Database (Denmark)

    Jørgensen, N O; Lacroix, Didier; Amundsen, F.H.;

    1999-01-01

    A paper which describes the work of an OECD research group. The group has suggested a grouping of dangerous materials, a quantitative risk assessment model and a decision support model which should allow tunnel operators to determine if a given material should be allowed throug a given tunnel...

  4. Virtual Processes and Quantum Tunnelling as Fictions

    Science.gov (United States)

    Arthur, Richard T. W.

    2012-01-01

    In this paper it is argued that virtual processes are dispensable fictions. The argument proceeds by a comparison with the phenomenon of quantum tunnelling. Building on an analysis of Levy-Leblond and Balibar, it is argued that, although the phenomenon known as quantum tunnelling certainly occurs and is at the basis of many paradigmatic quantum…

  5. Superconducting Super Collider Laboratory : tunnel boring

    CERN Multimedia

    SSC Media Production

    1999-01-01

    This film will take you down into the tunnel, show you the technology involved in boring the tunnel, and show what the SSC fmeans to the U.S. in terms of scientific discovery, innovative collaborations with industry and stimulating the job base nation-wide.

  6. 78 FR 46117 - National Tunnel Inspection Standards

    Science.gov (United States)

    2013-07-30

    ... September of 2009, and is another activity that FHWA conducted in partnership with AASHTO and NCHRP to... on this measure was a little over 24 months (2.05 years). \\11\\ The definition of a highway tunnel..., including tribally and federally owned tunnels. 650.505 Definitions At-grade Roadway. A definition for at...

  7. A Supermagnetic Tunnel Full of Subatomic Action

    CERN Multimedia

    2008-01-01

    Last year, before the gigantic hadron supercollider at CERN research facility was installed underground, a photographer captured this picture of a 1,950 metric ton tunnel containing giant magnets that will be placed in a tunnel and kept at near-zero temperatures.

  8. Ultrasonographic assessment of carpal tunnel biomechanics

    NARCIS (Netherlands)

    van Doesburg, M.H.M.

    2012-01-01

    In this thesis, we searched for a way to assess flexor tendon and median nerve biomechanics, as well as subsynovial connective tissue thickness (SSCT) in the carpal tunnel with ultrasound, and tried to see if these patterns would give a clue towards understanding the etiology of carpal tunnel syndro

  9. Prediction of swelling rocks strain in tunneling

    Science.gov (United States)

    Parsapour, D.; Fahimifar, A.

    2016-05-01

    Swelling deformations leading to convergence of tunnels may result in significant difficulties during the construction, in particular for long term use of tunnels. By extracting an experimental based explicit analytical solution for formulating swelling strains as a function of time and stress, swelling strains are predicted from the beginning of excavation and during the service life of tunnel. Results obtained from the analytical model show a proper agreement with experimental results. This closed-form solution has been implemented within a numerical program using the finite element method for predicting time-dependent swelling strain around tunnels. Evaluating effects of swelling parameters on time-dependent strains and tunnel shape on swelling behavior around the tunnel according to this analytical solution is considered. The ground-support interaction and consequent swelling effect on the induced forces in tunnel lining is considered too. Effect of delay in lining installation on swelling pressure which acting on the lining and its structural integrity, is also evaluated. A MATLAB code of " SRAP" is prepared and applied to calculate all swelling analysis around tunnels based on analytical solution.

  10. Energy saving in tunnel entrance lighting.

    NARCIS (Netherlands)

    Schreuder, D.A. & Swart, L.

    1993-01-01

    Tunnel entrances may present themselves during the day as a "black hole" in which no details can be perceived. In order to ensure safe and comfortable driving at high speeds, the entrance zone must be lit to a high luminance level. Modern tunnel lighting technology is focused on two aspects: (1

  11. Colloquium: Time-resolved scanning tunneling microscopy

    NARCIS (Netherlands)

    Houselt, van Arie; Zandvliet, Harold J.W.

    2010-01-01

    Scanning tunneling microscopy has revolutionized our ability to image, study, and manipulate solid surfaces on the size scale of atoms. One important limitation of the scanning tunneling microscope (STM) is, however, its poor time resolution. Recording a standard image with a STM typically takes abo

  12. Flow-based detection of DNS tunnels

    NARCIS (Netherlands)

    Ellens, W.; Zuraniewski, P.W.; Sperotto, A.; Schotanus, H.A.; Mandjes, M.; Meeuwissen, H.B.

    2013-01-01

    DNS tunnels allow circumventing access and security policies in firewalled networks. Such a security breach can be misused for activities like free web browsing, but also for command & control traffic or cyber espionage, thus motivating the search for effective automated DNS tunnel detection techniq

  13. Flow-Based Detection of DNS Tunnels

    NARCIS (Netherlands)

    Ellens, W.; Żuraniewski, P.; Sperotto, A.; Schotanus, H.; Mandjes, M.; Meeuwissen, E.

    2013-01-01

    DNS tunnels allow circumventing access and security policies in firewalled networks. Such a security breach can be misused for activities like free web browsing, but also for command & control traffic or cyber espionage, thus motivating the search for effective automated DNS tunnel detection techniq

  14. Spin-valley filter and tunnel magnetoresistance in asymmetrical silicene magnetic tunnel junctions

    Science.gov (United States)

    Wang, Dali; Huang, Zeyuan; Zhang, Yongyou; Jin, Guojun

    2016-05-01

    The spin and valley transports and tunnel magnetoresistance are studied in a silicene-based asymmetrical magnetic tunnel junction consisting of a ferromagnetic tunnel barrier, sandwiched between a ferromagnetic electrode and a normal electrode. For such an asymmetrical silicene junction, a general formulism is established. The numerical results show that the spin-valley resolved conductances strongly depend on the magnetization orientation of the ferromagnetic tunnel barrier, and the fully spin-valley polarized current can be realized by tuning a perpendicularly applied electric field. We also find that the tunnel magnetoresistance in this case can be effectively modified by the external electric field when the conductance is fully spin-valley polarized. In particular, the exchange field in the ferromagnetic electrode can further substantially enhance the tunnel magnetoresistance of the system. Our work provides a practical method for electric and magnetic manipulation of valley/spin polarization and tunnel magnetoresistance.

  15. [Carpal tunnel syndrome. Current approaches].

    Science.gov (United States)

    Kouyoumdjian, J A

    1999-06-01

    A clinical, epidemiological and nerve conduction studies report on carpal tunnel syndrome was done after electrophysiological author's experience on 668 cases and literature review. The median nerve underwent focal (nodal) or segmental demyelination after compression on carpal tunnel, 3-4 distal to wrist fold. The symptomatic complex includes nocturnal hands numbness and paraesthesia, mostly bilateral and between 40-60 years old. Familial cases are described and the gene could encode thick transverse carpal ligament. Anthropomorphic findings could also bring about an additional risk, but with low significance. Magnetic resonance could be a useful tool for selected atypical cases. Conservative treatment and controversies on surgery timing are discussed. Classical conduction studies on median nerve reveal a prolonged distal segmental sensory latency and also on distal motor latency. Increasing sensitivity may be reach using additional methods such as, median mixed mid-palm latency, comparative mid-palm latency median/ulnar, comparative sensory latency median/radial and median/ulnar, inching method from wrist to palm recording on index/middle finger and comparative motor median/ulnar recording on lumbrical/interosseous muscle.

  16. Temporary closure of the tunnel

    CERN Document Server

    Relations with the Host States Service

    2005-01-01

    Owing to major maintenance work, the tunnel linking the various parts of the CERN site will be closed from Monday 4 July to Sunday 24 July 2005 The Host State authorities have given authorisation for persons employed by CERN or the Institutes to travel and for goods belonging to these entities to be transported between the various parts of the site via Gate E (Charles de Gaulle) while this work is being carried out, subject to strict compliance with the Rules for the Use of the Tunnel (see http://dsu.web.cern.ch/dsu/dsum/hsr/DOCUMENTS/8200980415.pdf). Gate E will thus be open between 7.00 a.m. and 7.00 p.m. from Monday to Friday during the period concerned. The rules governing the use of Gate E to enter the Meyrin site between 7.30 a.m. and 9.00 a.m. or to leave the site between 5.00 p.m. and 6.30 p.m. (see http://dsu.web.cern.ch/dsu/dsum/hsr/DOCUMENTS/12222_041027.pdf)) will remain unaffected by this temporary authorisation. Relations with the Host States Service and TS-FM Group

  17. CARPAL TUNNEL SYNDROME IN CYCLISTS

    Science.gov (United States)

    Sousa, Daniel; Sassul, Nicolás

    2017-01-01

    Objectives: About a group of cyclists, professionals / amateurs, Mountain bike, road and triathlon; achieve a good diagnosis of the disease, with a good clinical examination and sectorized according EGM injury evoked potentials. Methods: Clinical examination and accurate test with different signs of pathology. EGM with evocative potential and conduction velocity. Results: After 25 track cyclists, 18 professionals, 22 male and 3 female; for 24 months. Through good clinical examination and EMG. We got that 70% had direct compression injuries Carpal tunnel for poor support on the handlebars. The rest were cervical praxis, by poor body position on the bike, taking cervico very steep angles / dorsal, during competitions or training for more than 2 hrs. Conclusion: A good prevention work with our teacher / cyclist in the position of deposrtista in ciclo simulador. Work in the gym, on tone and elongation of the upper limb. A good EGM, made with a specialist physiatrist. It leads to the correct diagnosis, leads to a good final treatment; which agreed that:* Cervical praxis, had good results with treatment Conservative / FST / vit.B12.* The Carpal tunnel own injuries, treatment was quirúrg. (Open surgery) with subsequent FST / vit..B12 with satisfactory return in time to sporting activity.

  18. IPv6 Tunneling Over IPV4

    Directory of Open Access Journals (Sweden)

    A.Sankara Narayanan

    2012-03-01

    Full Text Available Due to the huge growth of the internet users, mobile users using internet connection makes development and implementation of IPv6 as an alternate solution. IPv6 is a long anticipated upgrade to the internets main communication protocol, which is called IPv4. The current address space provided by IPv4, with only4, 294, 967, 296 addresses. Nowadays IPv6 tunneling over IPv4 are widely used to form the global IPv6 Internet. The IPv6 128-bit address scheme it should provide enough addresses for everyones computer. Tunneling provides a path to use an existing IPv4 to IPv6. This paper describes typical IPv6 tunneling and tunnel brokers deployment in real IP networks. In the deployment of IPv6, it is a well adopted practice that IPv6 networks are interconnected via IPv6 over IPv4 (IPv6/IPv4 tunnels.

  19. Characterization of magnetic tunnel junction test pads

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Kjær, Daniel; Nielsen, Peter Folmer

    2015-01-01

    We show experimentally as well as theoretically that patterned magnetic tunnel junctions can be characterized using the current-in-plane tunneling (CIPT) method, and the key parameters, the resistance-area product (RA) and the tunnel magnetoresistance (TMR), can be determined. The CIPT method...... on square tunnel junction pads with varying sizes and analyze the measured data using both the original and the modified CIPT model. Thus, we determine in which sample size range the modified CIPT model is needed to ensure validity of the extracted sample parameters, RA and TMR. In addition, measurements...... as a function of position on a square tunnel junction pad are used to investigate the sensitivity of the measurement results to probe misalignment....

  20. Concept development for HLW disposal research tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Queon, S. K.; Kim, K. S.; Park, J. H.; Jeo, W. J.; Han, P. S. [KAERI, Taejon (Korea, Republic of)

    2003-10-01

    In order to dispose high-level radioactive waste in a geological formation, it is necessary to assess the safety of a disposal concept by excavating a research tunnel in the same geological formation as the host rock mass. The design concept of a research tunnel depends on the actual disposal concept, repository geometry, experiments to be carried at the tunnel, and geological conditions. In this study, analysis of the characteristics of the disposal research tunnel, which is planned to be constructed at KAERI site, calculation of the influence of basting impact on neighbor facilities, and computer simuation for mechanical stability analysis using a three-dimensional code, FLAC3D, had been carried out to develop the design concept of the research tunnel.

  1. Control of tunneling by adapted signals

    CERN Document Server

    Ivlev, B I

    2000-01-01

    Process of quantum tunneling of particles in various physical systems can be effectively controlled even by a weak and slow varying in time electromagnetic signal if to adapt specially its shape to a particular system. During an under-barrier motion of a particle such signal provides a "coherent" assistance of tunneling by the multi-quanta absorption resulting in a strong enhancement of the tunneling probability. The semiclassical approach based on trajectories in the complex time is developed for tunneling in a non-stationary field. Enhancement of tunneling occurs when a singularity of the signal coincides in position at the complex time plane with a singularity of the classical Newtonian trajectory of the particle. The developed theory is also applicable to the over-barrier reflection of particles and to reflection of classical waves (electromagnetic, hydrodynamic, etc.) from a spatially-smooth medium.

  2. Experimental evidence for Wigner's tunneling time

    CERN Document Server

    Camus, Nicolas; Fechner, Lutz; Klaiber, Michael; Laux, Martin; Mi, Yonghao; Hatsagortsyan, Karen Z; Pfeifer, Thomas; Keitel, Christoph H; Moshammer, Robert

    2016-01-01

    Tunneling of a particle through a potential barrier remains one of the most remarkable quantum phenomena. Owing to advances in laser technology, electric fields comparable to those electrons experience in atoms are readily generated and open opportunities to dynamically investigate the process of electron tunneling through the potential barrier formed by the superposition of both laser and atomic fields. Attosecond-time and angstrom-space resolution of the strong laser-field technique allow to address fundamental questions related to tunneling, which are still open and debated: Which time is spent under the barrier and what momentum is picked up by the particle in the meantime? In this combined experimental and theoretical study we demonstrate that for strong-field ionization the leading quantum mechanical Wigner treatment for the time resolved description of tunneling is valid. We achieve a high sensitivity on the tunneling barrier and unambiguously isolate its effects by performing a differential study of t...

  3. Detecting DNS Tunnels Using Character Frequency Analysis

    CERN Document Server

    Born, Kenton

    2010-01-01

    High-bandwidth covert channels pose significant risks to sensitive and proprietary information inside company networks. Domain Name System (DNS) tunnels provide a means to covertly infiltrate and exfiltrate large amounts of information passed network boundaries. This paper explores the possibility of detecting DNS tunnels by analyzing the unigram, bigram, and trigram character frequencies of domains in DNS queries and responses. It is empirically shown how domains follow Zipf's law in a similar pattern to natural languages, whereas tunneled traffic has more evenly distributed character frequencies. This approach allows tunnels to be detected across multiple domains, whereas previous methods typically concentrate on monitoring point to point systems. Anomalies are quickly discovered when tunneled traffic is compared to the character frequency fingerprint of legitimate domain traffic.

  4. Prediction Study of Tunnel Collapse Risk in Advance based on Efficacy Coefficient Method and Geological Forecast

    Directory of Open Access Journals (Sweden)

    QIU Daohong

    2014-08-01

    Full Text Available Collapse is one of the most common accidents in underground constructions. Risk evaluation is the method of measuring the risk of chamber collapse. To ensure the safety of construction, a risk evaluation model of tunnel collapse based on an efficacy coefficient method and geological prediction was put forward. Based on the comprehensive analysis of collapse factors, five main factors including rock uniaxial compressive strength, surrounding rock integrated coefficient, state of discontinuous structural planes, the angle between tunnel axis and major structural plane and underground water were chosen as the risk evaluation indices of tunnel collapse. The evaluation indices were quantitatively described by using TSP203 system and core-drilling to establish the risk early warning model of tunnel collapse based on the basic principle of the efficacy coefficient method. The model established in this research was applied in the collapse risk recognition of Kiaochow Bay subsea tunnel in Qingdao, China. The results showed that the collapse risk recognition method presents higher prediction accuracy and provided a new idea for the risk prediction of tunnel collapse.

  5. Safe retaining pressures for pressurized tunnel face using nonlinear failure criterion and reliability theory

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-li; YAO Cong; ZHANG Jia-hua

    2016-01-01

    Based on the active failure mechanism and passive failure mechanism for a pressurized tunnel face, the analytical solutions of the minimum collapse pressure and maximum blowout pressure that could maintain the stability of pressurized tunnel faces were deduced using limit analysis in conjunction with nonlinear failure criterion under the condition of pore water pressure. Due to the objective existence of the parameter randomness of soil, the statistical properties of random variables were determined by the maximum entropy principle, and the Monte Carlo method was employed to calculate the failure probability of a pressurized tunnel. The results show that the randomness of soil parameters exerts great influence on the stability of a pressurized tunnel, which indicates that the research should be done on the topic of determination of statistical distribution for geotechnical parameters and the level of variability. For the failure probability of a pressurized tunnel under multiple failure modes, the corresponding safe retaining pressures and optimal range of safe retaining pressures are calculated by introducing allowable failure probability and minimum allowable failure probability. The results can provide practical use in the pressurized tunnel engineering.

  6. Dynamic Analysis the Groundwater of Daban Mountain Tunnel and Valuation the Function of the Tunnel%大坂山隧道地下水动态分析及对隧道作用评估

    Institute of Scientific and Technical Information of China (English)

    邓友生; 何平; 周成林; 刘洪金; 李永福; 马忠英; 刘国玉

    2004-01-01

    Base on the groundwater yield, water temperature and hydrochemistry change of the groundwater, we can analyze that the summer water content is obviously greater than winter water content where the in and-out wall rock of the Daban Mountain tunnel. The groundwater supply has the extensity and the seasonality. The groundwater content of the middle tunnel wall rock changes relatively steady, mainly supply through horizontal direction. And the total groundwater content is relatively little and steady in winter. The water pressure of the wall rock cranny is little. It has the fluent drainage system to dredge groundwater, which cannot constitute a threat to the tunnel lining. And the cold-proof sluice hole can normally work to drain water.

  7. Water

    Directory of Open Access Journals (Sweden)

    E. Sanmuga Priya

    2017-05-01

    Full Text Available Phytoremediation through aquatic macrophytes treatment system (AMATS for the removal of pollutants and contaminants from various natural sources is a well established environmental protection technique. Water hyacinth (Eichhornia crassipes, a worst invasive aquatic weed has been utilised for various research activities over the last few decades. The biosorption capacity of the water hyacinth in minimising various contaminants present in the industrial wastewater is well studied. The present review quotes the literatures related to the biosorption capacity of the water hyacinth in reducing the concentration of dyestuffs, heavy metals and minimising certain other physiochemical parameters like TSS (total suspended solids, TDS (total dissolved solids, COD (chemical oxygen demand and BOD (biological oxygen demand in textile wastewater. Sorption kinetics through various models, factors influencing the biosorption capacity, and role of physical and chemical modifications in the water hyacinth are also discussed.

  8. Analysis of Blast Wave Propagation Inside Tunnel

    Institute of Scientific and Technical Information of China (English)

    LIU Jingbo; YAN Qiushi; WU Jun

    2008-01-01

    The explosion inside tunnel would generate blast wave which transmits through the longi tudinal tunnel.Because of the close-in effects of the tunnel and the reflection by the confining tunnel structure,blast wave propagation inside tunnel is distinguished from that in air.When the explosion happens inside tunnel,the overpressure peak is higher than that of explosion happening in air.The continuance time of the biast wave also becomes longer.With the help of the numerical simu lation finite element software LS-DYNA.a three-dimensional nonlinear dynamic simulation analysis for an explosion experiment inside tunnel was carried out.LS-DYNA is a fully integrated analysis program specifically designed for nonlinear dynamics and large strain problems.Compared with the experimental results.the simulation results have made the material parameters of numerical simulation model available.By using the model and the same material parameters,many results were adopted by calculating the model under different TNT explosion dynamites.Then the method of dimensional analysis was Used for the Simulation resufts.AS Overpressures of the explosion biast wave are the governing factor in fhe tunnel responses.a formula for the explosion biast wave overpressure at a certain distance from the detonation center point inside the tunnel was de rived by using the dimensional analysis theory.By cornparing the results computed by the fromula with experimental results which were obtained before.the formula was proved to be very applicable at some instance.The research may be helpful to estimate rapidly the effect of internal explosion of tunnel on the structure.

  9. Study on the Integrated Geophysic Methods and Application of Advanced Geological Detection for Complicated Tunnel

    Science.gov (United States)

    Zhou, L.; Xiao, G.

    2014-12-01

    The engineering geological and hydrological conditions of current tunnels are more and more complicated, as the tunnels are elongated with deeper depth. In constructing these complicated tunnels, geological hazards prone to occur as induced by unfavorable geological bodies, such as fault zones, karst or hydrous structures, etc. The working emphasis and difficulty of the advanced geological exploration for complicated tunnels are mainly focused on the structure and water content of these unfavorable geological bodies. The technical aspects of my paper systematically studied the advanced geological exploration theory and application aspects for complicated tunnels, with discussion on the key technical points and useful conclusions. For the all-aroundness and accuracy of advanced geological exploration results, the objective of my paper is targeted on the comprehensive examination on the structure and hydrous characteristic of the unfavorable geological bodies in complicated tunnels. By the multi-component seismic modeling on a more real model containing the air medium, the wave field response characteristics of unfavorable geological bodies can be analyzed, thus providing theoretical foundation for the observation system layout, signal processing and interpretation of seismic methods. Based on the tomographic imaging theory of seismic and electromagnetic method, 2D integrated seismic and electromagnetic tomographic imaging and visualization software was designed and applied in the advanced drilling hole in the tunnel face, after validation of the forward and inverse modeling results on theoretical models. The transmission wave imaging technology introduced in my paper can be served as a new criterion for detection of unfavorable geological bodies. After careful study on the basic theory, data processing and interpretation, practical applications of TSP and ground penetrating radar (GPR) method, as well as serious examination on their application examples, my paper

  10. Lep vertical tunnel movements - lessons for future colliders

    Energy Technology Data Exchange (ETDEWEB)

    Pitthan, R. [CERN-Conseil Europeen pour la recherche nucleaire, Clic-Study Group and the Survey Group, Geneve (Switzerland)

    1999-07-01

    The data from 10 years of vertical surveys verify for all of LEP the previous observation, localized to region P1, that LEP floor movements are predominantly deterministic. This rules out the ATL model as being correct for this tunnel. If generalized, for yearly movements a random ATL model underestimates the possible maximum long-term motions. In contrast, extrapolation of the LEP vertical data to the short-term (hours and days) time-scale shows that the random approach predicts larger short-term movements than the deterministic model. This means that simulations using the ATL hypothesis are overtly pessimistic with regard to the frequency of operational realignments required. Depending on the constants chosen in the models these differences can be large, of the order of a magnitude and more. This paper deals solely with the directly measured months-to-years tunnel motions in rock, and the extrapolation of such ground motions to hourly or daily time-spans It does not, address the important question of the contribution of hourly-scale movements of the accelerator components, which could have a random part, to the combined motion. Nor does it address the question of movements of accelerator tunnels like HERA or TRISTAN which are built in water and debris, and not in solid rock. (author)

  11. First Principles Study of Electron Tunneling through Ice

    KAUST Repository

    Cucinotta, Clotilde S.

    2012-10-25

    With the aim of understanding electrochemical scanning tunnel microscopy experiments in an aqueous environment, we investigate electron transport through ice in the coherent limit. This is done by using the nonequilibrium Greens functions method, implemented within density functional theory, in the self-interaction corrected local density approximation. In particular, we explore different ice structures and different Au electrode surface orientations. By comparing the decay coefficient for different thicknesses to the ice complex band structure, we find that the electron transport occurs via tunneling with almost one-dimensional character. The slow decay of the current with the ice thickness is largely due to the small effective mass of the conduction electrons. Furthermore, we find that the calculated tunneling decay coefficients at the Fermi energy are not sensitive to the structural details of the junctions and are at the upper end of the experimental range for liquid water. This suggests that linear response transport measurements are not capable of distinguishing between different ordered ice structures. However, we also demonstrate that a finite bias measurement may be capable of sorting polar from nonpolar interfaces due to the asymmetry of the current-voltage curves for polar interfaces. © 2012 American Chemical Society.

  12. Prototype test study on mechanical characteristics of segmental lining structure of underwater railway shield tunnel

    Institute of Scientific and Technical Information of China (English)

    He Chuan; Feng Kun; Yan Qixiang

    2014-01-01

    Based on the first underwater railway shield tunnel,the Shiziyang shield tunnel of Guangzhou Zhu-jiang River,the prototype test was carried out against its segmental lining structure by using“multi-function shield tunnel structure test system”. And the mechanical characteristics of segmental lining structure using straight assembling and staggered assembling were studied deeply. The results showed that,the mechanical characteristics of segmental lining structure varied with the water pressures;especially after cracking,the high water pressure played a significant role in slowing down the growing inner force and deformation. It also testi-fied that the failure characteristics varied with straight assembling structure and staggered assembling structure. Shear failure often occurred near longitudinal seam when using straight assembling.

  13. Quantitative risk assessment modeling for nonhomogeneous urban road tunnels.

    Science.gov (United States)

    Meng, Qiang; Qu, Xiaobo; Wang, Xinchang; Yuanita, Vivi; Wong, Siew Chee

    2011-03-01

    Urban road tunnels provide an increasingly cost-effective engineering solution, especially in compact cities like Singapore. For some urban road tunnels, tunnel characteristics such as tunnel configurations, geometries, provisions of tunnel electrical and mechanical systems, traffic volumes, etc. may vary from one section to another. These urban road tunnels that have characterized nonuniform parameters are referred to as nonhomogeneous urban road tunnels. In this study, a novel quantitative risk assessment (QRA) model is proposed for nonhomogeneous urban road tunnels because the existing QRA models for road tunnels are inapplicable to assess the risks in these road tunnels. This model uses a tunnel segmentation principle whereby a nonhomogeneous urban road tunnel is divided into various homogenous sections. Individual risk for road tunnel sections as well as the integrated risk indices for the entire road tunnel is defined. The article then proceeds to develop a new QRA model for each of the homogeneous sections. Compared to the existing QRA models for road tunnels, this section-based model incorporates one additional top event-toxic gases due to traffic congestion-and employs the Poisson regression method to estimate the vehicle accident frequencies of tunnel sections. This article further illustrates an aggregated QRA model for nonhomogeneous urban tunnels by integrating the section-based QRA models. Finally, a case study in Singapore is carried out.

  14. The ventilation and climate modelling of rapid development tunnel drivages

    Energy Technology Data Exchange (ETDEWEB)

    Lowndes, I.S.; Crossley, A.J.; Yang, Z.Y. [University of Nottingham, Nottingham (United Kingdom). School of Chemical Environmental & Mining Engineering

    2004-03-01

    The extraction of minerals and coal at greater depth, employing higher-powered machinery to increase production levels, has imposed an increased burden on ventilation systems to maintain an acceptable working environment. There may be an economic or practical limit to the climatic improvement that may be obtained by the sole use of ventilation air. Where this limit is identified, there may be the need to consider the selective application of air-cooling systems. This paper details the construction of a computer based climatic prediction tool developed at the University of Nottingham. The current model predicts the psychrometric and thermodynamic conditions within long rapid development single entry tunnel drivages. The model takes into account the mass and heat transfer between the strata, water, machinery and the ventilation air. The results produced by the model have been correlated against ventilation, climatic and operational data, obtained from a number of rapid tunnel developments within UK deep coalmines. The paper details the results of a series of correlation and validation studies conducted against the ventilation and climate survey data measured within 105s district Tail Gate tunnel development at Maltby Colliery, UK. The paper concludes by presenting the results of a case study that illustrate the application of the validated model to the design and operation of an integrated mine ventilation and cooling system. The case study illustrates the effect that an increased depth and hence increased virgin strata temperature has on the climate experienced within rapid tunnel developments. Further investigations were performed to identify the optimum cooling strategy that should be adopted to maintain a satisfactory climate at the head of the drivage.

  15. Application of Doppler global velocimetry in cryogenic wind tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Willert, C.; Stockhausen, G.; Beversdorff, M.; Klinner, J. [German Aerospace Center (DLR), Institute of Propulsion Technology, Koeln (Germany); Lempereur, C.; Barricau, P. [DMAE, ONERA, Toulouse Cedex (France); Quest, J.; Jansen, U. [European Transonic Wind Tunnel (ETW), Koeln (Germany)

    2005-08-01

    A specially designed Doppler global velocimetry system (DGV, planar Doppler velocimetry) was developed and installed in a high-speed cryogenic wind tunnel facility for use at free stream Mach numbers between 0.2 and 0.88, and pressures between 1.2 bar and 3.3 bar. Particle seeding was achieved by injecting a mixture of gaseous nitrogen and water vapor into the dry and cold tunnel flow, which then immediately formed a large amount of small ice crystals. Given the limited physical and optical access for this facility, DGV is considered the best choice for non-intrusive flow field measurements. A multiple branch fiber imaging bundle attached to a common DGV image receiving system simultaneously viewed a common area in the flow field from three different directions through the wind tunnel side walls. The complete imaging system and fiber-fed light sheet generators were installed inside the normally inaccessible pressure plenum surrounding the wind tunnel's test section. The system control and frequency-stabilized laser system were placed outside of the pressure shell. With a field of view of 300 x 300 mm{sup 2}, the DGV system acquired flow maps at a spatial resolution of 3 x 3 mm{sup 2} in the wake of simple vortex generators as well as in the wake of different wing-tip devices on a half-span aircraft model. Although problems mainly relating to light reflections and icing on the observation windows significantly impaired part of the measurements, the remotely controlled hardware operated reliably over the course of three months. (orig.)

  16. Area and shape changes of the carpal tunnel in response to tunnel pressure.

    Science.gov (United States)

    Li, Zong-Ming; Masters, Tamara L; Mondello, Tracy A

    2011-12-01

    Carpal tunnel mechanics is relevant to our understanding of median nerve compression in the tunnel. The compliant characteristics of the tunnel strongly influence its mechanical environment. We investigated the distensibility of the carpal tunnel in response to tunnel pressure. A custom balloon device was designed to apply controlled pressure. Tunnel cross sections were obtained using magnetic resonance imaging to derive the relationship between carpal tunnel pressure and morphological parameters at the hook of hamate. The results showed that the cross-sectional area (CSA) at the level of the hook of hamate increased, on average, by 9.2% and 14.8% at 100 and 200 mmHg, respectively. The increased CSA was attained by a shape change of the cross section, displaying increased circularity. The increase in CSA was mainly attributable to the increase of area in the carpal arch region formed by the transverse carpal ligament. The narrowing of the carpal arch width was associated with an increase in the carpal arch. We concluded that the carpal tunnel is compliant to accommodate physiological variations of the carpal tunnel pressure, and that the increase in tunnel CSA is achieved by increasing the circularity of the cross section.

  17. Simulation of groundwater drainage into a tunnel in fractured rock and numerical analysis of leakage remediation, Romeriksporten tunnel, Norway

    Science.gov (United States)

    Kitterød, N.-O.; Colleuille, H.; Wong, W. K.; Pedersen, T. S.

    2000-09-01

    Standard geostatistical methods for simulation of heterogeneity were applied to the Romeriksporten tunnel in Norway, where water was leaking through high-permeable fracture zones into the tunnel while it was under construction, causing drainage problems on the surface. After the tunnel was completed, artificial infiltration of water into wells drilled from the tunnel was implemented to control the leakage. Synthetic heterogeneity was generated at a scale sufficiently small to simulate the effects of remedial actions that were proposed to control the leakage. The flow field depends on the variance of permeabilities and the covariance model used to generate the heterogeneity. Flow channeling is the most important flow mechanism if the variance of the permeability field is large compared to the expected value. This condition makes the tunnel leakage difficult to control. The main effects of permeability changes due to sealing injection are simulated by a simple perturbation of the log-normal probability density function of the permeability. If flow channeling is the major transport mechanism of water into the tunnel, implementation of artificial infiltration of water to control the leakage requires previous chemical-sealing injection to be successful. Résumé. Des méthodes géostatistiques standard ont été employées pour simuler l'hétérogénéité des zones de fractures à fortes perméabilitées dans lesquelles, au cours de la construction du tunnel ferroviaire de Romeriksporten (Norvège), l'eau s'est écoulée, causant des problèmes de drainage en surface. Quand les travaux ont été terminés, l'injection d'eau dans des puits forés à partir du tunnel a été réalisée pour contrôler ces infiltrations. Une hétérogénéité synthétique a été créée à une échelle suffisamment petite pour simuler les effets de l'injection d'eau. Le champ des écoulements dépend de la variance des perméabilités et de la covariance du modèle utilisé pour g

  18. Direct Approach to Quantum Tunneling

    Science.gov (United States)

    Andreassen, Anders; Farhi, David; Frost, William; Schwartz, Matthew D.

    2016-12-01

    The decay rates of quasistable states in quantum field theories are usually calculated using instanton methods. Standard derivations of these methods rely in a crucial way upon deformations and analytic continuations of the physical potential and on the saddle-point approximation. While the resulting procedure can be checked against other semiclassical approaches in some one-dimensional cases, it is challenging to trace the role of the relevant physical scales, and any intuitive handle on the precision of the approximations involved is at best obscure. In this Letter, we use a physical definition of the tunneling probability to derive a formula for the decay rate in both quantum mechanics and quantum field theory directly from the Minkowski path integral, without reference to unphysical deformations of the potential. There are numerous benefits to this approach, from nonperturbative applications to precision calculations and aesthetic simplicity.

  19. Tunnel effect wave energy detection

    Science.gov (United States)

    Kaiser, William J. (Inventor); Waltman, Steven B. (Inventor); Kenny, Thomas W. (Inventor)

    1995-01-01

    Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

  20. Tunneling magnetoresistance of silicon chains

    Science.gov (United States)

    Matsuura, Yukihito

    2016-05-01

    The tunneling magnetoresistance (TMR) of a silicon chain sandwiched between nickel electrodes was examined by using first-principles density functional theory. The relative orientation of the magnetization in a parallel-alignment (PA) configuration of two nickel electrodes enhanced the current with a bias less than 0.4 V compared with that in an antiparallel-alignment configuration. Consequently, the silicon chain-nickel electrodes yielded good TMR characteristics. In addition, there was polarized spin current in the PA configuration. The spin polarization of sulfur atoms functioning as a linking bridge between the chain and nickel electrode played an important role in the magnetic effects of the electric current. Moreover, the hybridization of the sulfur 3p orbital and σ-conjugated silicon 3p orbital contributed to increasing the total current.

  1. Hawking Radiation and Classical Tunneling

    CERN Document Server

    Tracy, Eugene R

    2015-01-01

    Acoustic waves in fluids undergoing the transition from sub- to supersonic flow satisfy governing equations similar to those for light waves in the immediate vicinity of a black hole event horizon. This acoustic analogy has been used by Unruh and others as a conceptual model for `Hawking radiation.' Here we use variational methods, originally introduced by Brizard for the study of linearized MHD, and ray phase space methods, to analyze linearized acoustics in the presence of background flows. The variational formulation endows the evolution equations with natural Hermitian and symplectic structures that prove useful for later analysis. We derive a $2\\times 2$ normal form governing the wave evolution in the vicinity of the `event horizon.' This shows that the acoustic model can be reduced locally (in ray phase space) to a standard (scalar) tunneling process weakly coupled to a unidirectional non-dispersive wave (the `incoming wave'). Given the normal form, the Hawking `thermal spectrum' can be derived by invok...

  2. Theory of dissociative tunneling ionization

    CERN Document Server

    Svensmark, Jens; Madsen, Lars Bojer

    2016-01-01

    We present a theoretical study of the dissociative tunneling ionization process. Analytic expressions for the nuclear kinetic energy distribution of the ionization rates are derived. A particularly simple expression for the spectrum is found by using the Born-Oppenheimer (BO) approximation in conjunction with the reflection principle. These spectra are compared to exact non-BO ab initio spectra obtained through model calculations with a quantum mechanical treatment of both the electronic and nuclear degrees freedom. In the regime where the BO approximation is applicable imaging of the BO nuclear wave function is demonstrated to be possible through reverse use of the reflection principle, when accounting appropriately for the electronic ionization rate. A qualitative difference between the exact and BO wave functions in the asymptotic region of large electronic distances is shown. Additionally the behavior of the wave function across the turning line is seen to be reminiscent of light refraction. For weak fiel...

  3. Homoepitaxial graphene tunnel barriers for spin transport

    Directory of Open Access Journals (Sweden)

    Adam L. Friedman

    2016-05-01

    Full Text Available Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. Here, we demonstrate that hydrogenation or fluorination of graphene can be used to create a tunnel barrier. We demonstrate successful tunneling by measuring non-linear IV curves and a weakly temperature dependent zero-bias resistance. We demonstrate lateral transport of spin currents in non-local spin-valve structures, and determine spin lifetimes with the non-local Hanle effect. We compare the results for hydrogenated and fluorinated tunnel and we discuss the possibility that ferromagnetic moments in the hydrogenated graphene tunnel barrier affect the spin transport of our devices.

  4. Rudolf Hermann, wind tunnels and aerodynamics

    Science.gov (United States)

    Lundquist, Charles A.; Coleman, Anne M.

    2008-04-01

    Rudolf Hermann was born on December 15, 1904 in Leipzig, Germany. He studied at the University of Leipzig and at the Aachen Institute of Technology. His involvement with wind tunnels began in 1934 when Professor Carl Wieselsberger engaged him to work at Aachen on the development of a supersonic wind tunnel. On January 6, 1936, Dr. Wernher von Braun visited Dr. Hermann to arrange for use of the Aachen supersonic wind tunnel for Army problems. On April 1, 1937, Dr. Hermann became Director of the Supersonic Wind Tunnel at the Army installation at Peenemunde. Results from the Aachen and Peenemunde wind tunnels were crucial in achieving aerodynamic stability for the A-4 rocket, later designated as the V-2. Plans to build a Mach 10 'hypersonic' wind tunnel facility at Kochel were accelerated after the Allied air raid on Peenemunde on August 17, 1943. Dr. Hermann was director of the new facility. Ignoring destruction orders from Hitler as WWII approached an end in Europe, Dr. Hermann and his associates hid documents and preserved wind tunnel components that were acquired by the advancing American forces. Dr. Hermann became a consultant to the Air Force at its Wright Field in November 1945. In 1951, he was named professor of Aeronautical Engineering at the University of Minnesota. In 1962, Dr. Hermann became the first Director of the Research Institute at the University of Alabama in Huntsville (UAH), a position he held until he retired in 1970.

  5. Pair Tunneling through Single Molecules

    Science.gov (United States)

    Raikh, Mikhail

    2007-03-01

    Coupling to molecular vibrations induces a polaronic shift, and can lead to a negative charging energy, U. For negative U, the occupation of the ground state of the molecule is even. In this situation, virtual pair transitions between the molecule and the leads can dominate electron transport. At low temperature, T, these transitions give rise to the charge-Kondo effect [1]. We developed the electron transport theory through the negative-U molecule [2] at relatively high T, when the Kondo correlations are suppressed. Two physical ingredients distinguish our theory from the transport through a superconducting grain coupled to the normal leads [3]: (i) in parallel with sequential pair-tunneling processes, single-particle cotunneling processes take place; (ii) the electron pair on the molecule can be created (or annihilated) by two electrons tunneling in from (or out to) opposite leads. We found that, even within the rate-equation description, the behavior of differential conductance through the negative-U molecule as function of the gate voltage is quite peculiar: the height of the peak near the degeneracy point is independent of temperature, while its width is proportional to T. This is in contrast to the ordinary Coulomb-blockade conductance peak, whose integral strength is T-independent. At finite source-drain bias, V>>T, the width of the conductance peak is ˜V, whereas the conventional Coulomb-blockade peak at finite V splits into two sharp peaks at detunings V/2, and -V/2. Possible applications to the gate-controlled current rectification and switching will be discussed. [1] A. Taraphder and P. Coleman, Phys. Rev. Lett. 66, 2814 (1991). [2] J. Koch, M. E. Raikh, and F. von Oppen, Phys. Rev. Lett. 96, 056803 (2006). [3] F. W. J. Hekking, L. I. Glazman, K. A. Matveev, and R. I. Shekhter, Phys. Rev. Lett. 70, 4138 (1993).

  6. Gray-box modelling approach for description of storage tunnel

    DEFF Research Database (Denmark)

    Harremoës, Poul; Carstensen, Jacob

    1999-01-01

    of the water in the overflow structures. The capacity of a pump draining the storage tunnel is estimated for two different rain events, revealing that the pump was malfunctioning during the first rain event. The proposed modeling approach can be used in automated online surveillance and control and implemented....... The model in the present paper provides on-line information on overflow volumes, pumping capacities, and remaining storage capacities. A linear overflow relation is found, differing significantly from the traditional deterministic modeling approach. The linearity of the formulas is explained by the inertia...

  7. Preliminary wind tunnel tests on the pedal wind turbine

    Science.gov (United States)

    Vinayagalingam, T.

    1980-06-01

    High solidity-low speed wind turbines are relatively simple to construct and can be used advantageously in many developing countries for such direct applications as water pumping. Established designs in this class, such as the Savonius and the American multiblade rotors, have the disadvantage that their moving surfaces require a rigid construction, thereby rendering large units uneconomical. In this respect, the pedal wind turbine recently reported by the author and which incorporates sail type rotors offers a number of advantages. This note reports preliminary results from a series of wind tunnel tests which were carried out to assess the aerodynamic torque and power characteristics of the turbine.

  8. Extraskeletal chondroma casuing carpal tunnel syndrome: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ok Hwa; Kim, Yeon Hee [Haeundae Paik Hospital, Inje University College of Medicine, Busan (Korea, Republic of)

    2014-03-15

    Carpal tunnel syndrome caused by extraskeletal chondroma has been scarcely reported in the literature. Authors report a case of carpal tunnel syndrome as a result of an extraskeletal chondroma arising within the carpal tunnel, and describe the radiological and pathological findings of the mass. We also discuss the differential diagnosis of the calcified space, occupying lesions that may occur in carpal tunnel.

  9. Pressure-morphology relationship of a released carpal tunnel.

    Science.gov (United States)

    Kim, Dong Hee; Marquardt, Tamara L; Gabra, Joseph N; Shen, Zhilei Liu; Evans, Peter J; Seitz, William H; Li, Zong-Ming

    2013-04-01

    We investigated morphological changes of a released carpal tunnel in response to variations of carpal tunnel pressure. Pressure within the carpal tunnel is known to be elevated in patients with carpal tunnel syndrome and dependent on wrist posture. Previously, increased carpal tunnel pressure was shown to affect the morphology of the carpal tunnel with an intact transverse carpal ligament (TCL). However, the pressure-morphology relationship of the carpal tunnel after release of the TCL has not been investigated. Carpal tunnel release (CTR) was performed endoscopically on cadaveric hands and the carpal tunnel pressure was dynamically increased from 10 to 120 mmHg. Simultaneously, carpal tunnel cross-sectional images were captured by an ultrasound system, and pressure measurements were recorded by a pressure transducer. Carpal tunnel pressure significantly affected carpal arch area (p 62 mm(2) at 120 mmHg. Carpal arch height, length, and width also significantly changed with carpal tunnel pressure (p carpal tunnel pressure increased, carpal arch height and length increased, but the carpal arch width decreased. Analyses of the pressure-morphology relationship for a released carpal tunnel revealed a nine times greater compliance than that previously reported for a carpal tunnel with an intact TCL. This change of structural properties as a result of transecting the TCL helps explain the reduction of carpal tunnel pressure and relief of symptoms for patients after CTR surgery.

  10. Band-to-Band Tunneling Transistors: Scalability and Circuit Performance

    Science.gov (United States)

    2013-05-01

    To better understand and evaluate tunnel field effect transistors (TFETs), a new TCAD analysis tool with dynamic nonlocal tunneling path...better understand and evaluate tunnel field effect transistors (TFETs), a new TCAD analysis tool with dynamic nonlocal tunneling path determination is...me complete my research with the best of practices. As a perennial procrastinator , my dissertation committee, Prof. Paul Wright, Prof. Sayeef

  11. The Thames Tideway Tunnel (3/3)

    CERN Document Server

    CERN. Geneva

    2012-01-01

    Lecture 3: Insight into a pioneering project at the cutting edge of engineering: the upgrade to London’s failing sewerage system. With a growing population and heavier rainfall, the River Thames is regularly polluted in breach of European Directive requirements. Two new storage and transfer tunnels will run up to 85m deep under the river and will intercept and divert sewer overflows to a treatment facility in east London. The challenges faced by constructing a tunnel project of this size under the river and through London’s historic urban environment will set a new UK record for this type of tunnelling.

  12. Application of Important Factors in Tunnel Projects

    Directory of Open Access Journals (Sweden)

    Siamak Bagherian

    2013-06-01

    Full Text Available The objective of this thesis is to improve the quality of the basis for making decisions about tender prices and budgets for tunnel projects by developing a model for the estimation of construction time and cost. The planning and constructing of extensions to existing road and railway networks is an ongoing mission of transport infrastructure development. For functional, aesthetic or environmental reasons, a large number of these extensions are planned as tunnels. In the planning and procurement phases of tunnel projects, numerous decisions have to be made in relation to the tender price and project budget.

  13. Carpal tunnel syndrome - anatomical and clinical correlations.

    Science.gov (United States)

    Iskra, Tomasz; Mizia, Ewa; Musial, Agata; Matuszyk, Aleksandra; Tomaszewski, Krzysztof A

    2013-01-01

    Carpal tunnel syndrome (CTS) is the most common and widely known of the entrapment neuropathies in which the body's peripheral nerves are compressed. Common symptoms of CTS involve the hand and result from compression of the median nerve within the carpal tunnel. In general, CTS develops when the tissues around the median nerve irritate or compress on the nerve along its course through the carpal tunnel, however often it is very difficult to determine cause of CTS. Proper treatment (conservative or surgical) usually can relieve the symptoms and restore normal use of the wrist and hand.

  14. A scaled down laboratory experiment of cross-borehole pulse radar signatures for detection of a terminated tunnel

    Science.gov (United States)

    Cho, Jae-Hyoung; Jung, Ji-Hyun; Kim, Se-Yun; Yook, Jong-Gwan

    2016-09-01

    In the cross-borehole pulse radar signatures measured near the front end of a terminated tunnel, the time-of-arrival (TOA) with fully penetrated tunnel is significantly shortened due to the relatively fast pulse propagation in an empty tunnel compared with the TOA obtained without a tunnel. To analyze the TOA variation with the protrusion length of the terminated tunnel from the line-of-sight between two antennas or boreholes, additional borehole pairs are required around the terminated tunnel in spite of their high construction costs. As an alternative, a laboratory scaled down experiment, which has a high ability to simulate different underground configurations, is designed for investigation into the TOA effects of tunnel termination. A round ceramic rod with a careful selection of its dielectric constant is immersed in pure water in a water tank and used to simulate the tunnel in the experiment. Coaxial fed dipole antennas with balanced wire and ferrite cores are used not only to suppress borehole-guided waves but also to generate a symmetric radiation pattern. The accuracy of the laboratory scaled down experiment is verified by the symmetricity of the measured diffraction pattern of the fully penetrated ceramic rod. Then, the TOA variation is measured for the protrusion length of the ceramic rod relative to the line-of-sight between two antennas from  +80 mm to  -80 mm with an equal step of 5 mm. Based on the scaled down experimental measurements of the TOA, it is found that a tunnel 1.2 m away from the measuring cross-borehole section closely approaches the scaled up variation curve under the same conditions of the protrusion length.

  15. Nature of radioactive contamination of components of ecosystems of streamflows from tunnels of Degelen massif.

    Science.gov (United States)

    Panitskiy, A V; Lukashenko, S N

    2015-06-01

    The paper provides data on environmental contamination due to radionuclides' migration with water. As a result of investigations there was obtained data on character of contamination of soil cover, surface water and underflow from tunnels of Degelen massif. Character of radionuclides' spatial distribution in environment was also shown. Mobility ranges of radionuclides' vertical and horizontal movements have been established in soils both across and along the stream flow. There was also shown a possibility to forecast radionuclides' concentration in soil by specific activity of these radionuclides in water. Different concentrations of radionuclides in associated components of the ecosystem (surface waters - ground waters - soils) have shown disequilibrium of their condition in this system. Generalization of investigation results for tunnel water streams' with water inflows, chosen as investigation objects in this work, allows to forecast radionuclides' behavior in meadow soils and other ecosystems of water streams from tunnels of Degelen test site. Based on analysis of curves, describing radionuclides' behavior in horizontal direction, we can forecast, that at this stage (137)Cs and (239+240)Pu would not be distributed more than 1.5 km from the access to the daylight surface, (90)Sr - not more than 2 km. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. NASA Glenn Icing Research Tunnel: 2014 Cloud Calibration

    Science.gov (United States)

    VanZante, Judith Foss; Ide, Robert F.; Steen, Laura; Acosta, Waldo J.

    2014-01-01

    The results of the December 2013 to February 2014 Icing Research Tunnel full icing cloud calibration are being presented to the SAE AC-9C committee, as represented in the 2014 cloud calibration report. The calibration steps included establishing a uniform cloud and conducting drop size and liquid water content calibrations. The goal of the calibration was to develop a uniform cloud, and to generate a transfer function from the inputs of air speed, spray bar atomizing air pressure and water pressure to the outputs of median volumetric drop diameter and liquid water content. This was done for both 14 CFR Parts 25 and 29, Appendix C (typical icing) and soon-to-be released Appendix O (supercooled large drop) conditions.

  17. Testing compost as an anti wind erosion agent in a wind tunnel

    NARCIS (Netherlands)

    Vos, de J.A.

    1996-01-01

    The potential of compost as an anti wind erosion agent was studied in a wind tunnel on a sandy soil susceptible to wind erosion. Soil treated with a compost-water mixture, which forms a crust on the soil surface after drying, was exposed to a series of increasing wind speeds. Two composts were

  18. Evaporation of HD Droplets From Nonporous, Inert Surfaces in TGA Microbalance Wind Tunnels

    Science.gov (United States)

    2008-09-01

    2007 4. TITLE AND SUBTITLE Evaporation of HD Droplets from Nonporous, Inert Surfaces in TGA Microbalancc Wind Tunnels 5a. CONTRACT NUMBER DAAD13...hr (lightly swirled on a rotating plateau). Then, the glass was rinsed with dematerialized water and dried (using appropriate fat-free non-felting

  19. Modeling cooking of chicken meat in industrial tunnel ovens with the Flory-Rehner theory

    NARCIS (Netherlands)

    Sman, van der R.G.M.

    2013-01-01

    In this paper we present a numerical model describing the heat and mass transport during the cooking of chicken meat in industrial tunnels. The mass transport is driven by gradients in the swelling pressure, which is described by the Flory-Rehner theory, which relates to the water holding capacity (

  20. Experimental study of fluid deicing system in the NASA Icing Research Tunnel

    Science.gov (United States)

    1983-01-01

    An investigation of the icing of horizontal control surfaces at the VFW in 1970 led them to select the NASA Icing Research Tunnel at LRC for their tests. Tests were performed for the VFW 614 aircraft. The TKS ice warning system, the Rosemont ice warning system and the liquid water content indicator were investigated and found to be appropriate for the aircraft.

  1. Tunneling time, exit time and exit momentum in strong field tunnel ionization

    Energy Technology Data Exchange (ETDEWEB)

    Teeny, Nicolas

    2016-10-18

    Tunnel ionization belongs to the fundamental processes of atomic physics. It is still an open question when does the electron tunnel ionize and how long is the duration of tunneling. In this work we solve the time-dependent Schroedinger equation in one and two dimensions and use ab initio quantum calculations in order to answer these questions. Additionally, we determine the exit momentum of the tunnel ionized electron from first principles. We find out results that are different from the assumptions of the commonly employed two-step model, which assumes that the electron ionizes at the instant of electric field maximum with a zero momentum. After determining the quantum final momentum distribution of tunnel ionized electrons we show that the two-step model fails to predict the correct final momentum. Accordingly we suggest how to correct the two-step model. Furthermore, we determine the instant at which tunnel ionization starts, which turns out to be different from the instant usually assumed. From determining the instant at which it is most probable for the electron to enter the tunneling barrier and the instant at which it exits we determine the most probable time spent under the barrier. Moreover, we apply a quantum clock approach in order to determine the duration of tunnel ionization. From the quantum clock we determine an average tunneling time which is different in magnitude and origin with respect to the most probable tunneling time. By defining a probability distribution of tunneling times using virtual detectors we relate both methods and explain the apparent discrepancy. The results found have in general an effect on the interpretation of experiments that measure the spectra of tunnel ionized electrons, and specifically on the calibration of the so called attoclock experiments, because models with imprecise assumptions are usually employed in order to interpret experimental results.

  2. Tunneling into quantum wires: Regularization of the tunneling Hamiltonian and consistency between free and bosonized fermions

    Science.gov (United States)

    Filippone, Michele; Brouwer, Piet W.

    2016-12-01

    Tunneling between a point contact and a one-dimensional wire is usually described with the help of a tunneling Hamiltonian that contains a δ function in position space. Whereas the leading-order contribution to the tunneling current is independent of the way this δ function is regularized, higher-order corrections with respect to the tunneling amplitude are known to depend on the regularization. Instead of regularizing the δ function in the tunneling Hamiltonian, one may also obtain a finite tunneling current by invoking the ultraviolet cutoffs in a field-theoretic description of the electrons in the one-dimensional conductor, a procedure that is often used in the literature. For the latter case, we show that standard ultraviolet cutoffs lead to different results for the tunneling current in fermionic and bosonized formulations of the theory, when going beyond leading order in the tunneling amplitude. We show how to recover the standard fermionic result using the formalism of functional bosonization and revisit the tunneling current to leading order in the interacting case.

  3. Construction of Foundation for 15-Foot Spin Tunnel

    Science.gov (United States)

    1934-01-01

    Completed foundation for the outer housing for the 15-Foot Spin Tunnel. Charles Zimmerman was given the assignment to design and build a larger spin tunnel that would supplant the 5-foot Vertical Wind Tunnel. Authorization to build the tunnel using funds from the Federal Public Works Administration (PWA) came in June 1933. Construction started in late winter 1934 and the tunnel was operational in April 1935. The initial construction costs were $64,000.

  4. Survey Of Wind Tunnels At Langley Research Center

    Science.gov (United States)

    Bower, Robert E.

    1989-01-01

    Report presented at AIAA 14th Aerodynamic Testing Conference on current capabilities and planned improvements at NASA Langley Research Center's major wind tunnels. Focuses on 14 major tunnels, 8 unique in world, 3 unique in country. Covers Langley Spin Tunnel. Includes new National Transonic Facility (NTF). Also surveys Langley Unitary Plan Wind Tunnel (UPWT). Addresses resurgence of inexpensive simple-to-operate research tunnels. Predicts no shortage of tools for aerospace researcher and engineer in next decade or two.

  5. Survey Of Wind Tunnels At Langley Research Center

    Science.gov (United States)

    Bower, Robert E.

    1989-01-01

    Report presented at AIAA 14th Aerodynamic Testing Conference on current capabilities and planned improvements at NASA Langley Research Center's major wind tunnels. Focuses on 14 major tunnels, 8 unique in world, 3 unique in country. Covers Langley Spin Tunnel. Includes new National Transonic Facility (NTF). Also surveys Langley Unitary Plan Wind Tunnel (UPWT). Addresses resurgence of inexpensive simple-to-operate research tunnels. Predicts no shortage of tools for aerospace researcher and engineer in next decade or two.

  6. Dielectric Sensors Based on Electromagnetic Energy Tunneling

    Directory of Open Access Journals (Sweden)

    Omar Siddiqui

    2015-03-01

    Full Text Available We show that metallic wires embedded in narrow waveguide bends and channels demonstrate resonance behavior at specific frequencies. The electromagnetic energy at these resonances tunnels through the narrow waveguide channels with almost no propagation losses. Under the tunneling behavior, high-intensity electromagnetic fields are produced in the vicinity of the metallic wires. These intense field resonances can be exploited to build highly sensitive dielectric sensors. The sensor operation is explained with the help of full-wave simulations. A practical setup consisting of a 3D waveguide bend is presented to experimentally observe the tunneling phenomenon. The tunneling frequency is predicted by determining the input impedance minima through a variational formula based on the Green function of a probe-excited parallel plate waveguide.

  7. Hi-tech Tunnel Sets World Record

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A sport utility vehicle takes the new direct route from Xi’an, capital city of northwest China’s Shaanxi Province, to Zhashui County through the Zhongnanshan Tunnel, which opened on January 21.With a total investment of nearly 3.2 billion yuan, the four-lane highway is the world’s longest double-tube tunnel, stretching 18.02 km.As a major part of the province’s expressway network, the tunnel connects Xi’an with southwest Shaanxi through the Qinling Mountains, shortening the previous three-hour trip to 40 minutes.The highway tunnel is also planned as part of a national highway linking north China’s Inner Mongolia Autonomous Region and south China’s Guangxi Zhuang Autonomous Region.

  8. Control over Rectification in Supramolecular Tunneling Junctions

    NARCIS (Netherlands)

    Wimbush, K.S.; Wimbush, Kim S.; Reus, William F.; van der Wiel, Wilfred Gerard; Reinhoudt, David; Whitesides, George M.; Nijhuis, C.A.; Velders, Aldrik

    2010-01-01

    In complete control: The magnitude of current rectification in well-defined supramolecular tunneling junctions can be controlled by changing the terminal functionality (red spheres) of dendrimers (gray spheres) immobilized on a supramolecular platform (see picture). Junctions containing biferrocene

  9. Low Speed Wind Tunnel Facility (LSWTF)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: This facility consists of a large-scale, low-speed open-loop induction wind tunnel which has been modified to house a linear turbine cascade. A 125-hp...

  10. Unknotting tunnels in hyperbolic 3-manifolds

    CERN Document Server

    Adams, Colin

    2012-01-01

    An unknotting tunnel in a 3-manifold with boundary is a properly embedded arc, the complement of an open neighborhood of which is a handlebody. A geodesic with endpoints on the cusp boundary of a hyperbolic 3-manifold and perpendicular to the cusp boundary is called a vertical geodesic. Given a vertical geodesic in a hyperbolic 3-manifold M, we find sufficient conditions for it to be an unknotting tunnel. In particular, if the vertical geodesic corresponds to a 4-bracelet, 5-bracelet or 6-bracelet in the universal cover and has short enough length, it must be an unknotting tunnel. Furthermore, we consider a vertical geodesic that satisfies the elder sibling property, which means that in the universal cover, every horoball except the one centered at infinity is connected to a larger horoball by a lift of the vertical geodesic. Such a vertical geodesic with length less than ln(2) is then shown to be an unknotting tunnel.

  11. Proton tunnelling in intermolecular hydrogen bonds

    Energy Technology Data Exchange (ETDEWEB)

    Horsewill, A.J. [Nottingham Univ. (United Kingdom); Johnson, M.R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Trommsdorff, H.P. [Grenoble-1 Univ., 38 (France)

    1997-04-01

    The wavefunctions of particles extend beyond the classically accessible regions of potential energy-surfaces (PES). A manifestation of this partial delocalization is the quantum-mechanical tunneling effect which enables a particle to escape from a metastable potential-well. Tunnelling is most important for the lightest atoms, so that the determination of its contribution to proton transfer, one of the most fundamental chemical reactions, is an important issue. QENS and NMR techniques have been employed to study the motion of protons in the hydrogen bond of benzoic-acid crystals, a system which has emerged as a particularly suitable model since proton transfer occurs in a near symmetric double-well potential. The influence of quantum tunnelling was revealed and investigated in these experiments. This work provides an experimental benchmark for theoretical descriptions of translational proton-tunnelling. (author). 7 refs.

  12. A century of wind tunnels since Eiffel

    Science.gov (United States)

    Chanetz, Bruno

    2017-08-01

    Fly higher, faster, preserve the life of test pilots and passengers, many challenges faced by man since the dawn of the twentieth century, with aviation pioneers. Contemporary of the first aerial exploits, wind tunnels, artificially recreating conditions encountered during the flight, have powerfully contributed to the progress of aeronautics. But the use of wind tunnels is not limited to aviation. The research for better performance, coupled with concern for energy saving, encourages manufacturers of ground vehicles to perform aerodynamic tests. Buildings and bridge structures are also concerned. This article deals principally with the wind tunnels built at ONERA during the last century. Somme wind tunnels outside ONERA, even outside France, are also evocated when their characteristics do not exist at ONERA.

  13. Modeling direct interband tunneling. I. Bulk semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Andrew, E-mail: pandrew@ucla.edu [Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, California 90095 (United States); Chui, Chi On [Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095 (United States)

    2014-08-07

    Interband tunneling is frequently studied using the semiclassical Kane model, despite uncertainty about its validity. Revisiting the physical basis of this formula, we find that it neglects coupling to other bands and underestimates transverse tunneling. As a result, significant errors can arise at low and high fields for small and large gap materials, respectively. We derive a simple multiband tunneling model to correct these defects analytically without arbitrary parameters. Through extensive comparison with band structure and quantum transport calculations for bulk InGaAs, InAs, and InSb, we probe the accuracy of the Kane and multiband formulas and establish the superiority of the latter. We also show that the nonlocal average electric field should be used when applying either of these models to nonuniform potentials. Our findings are important for efficient analysis and simulation of bulk semiconductor devices involving tunneling.

  14. Computer graphic of LHC in the tunnel

    CERN Multimedia

    1996-01-01

    A computer-generated image of the LHC particle accelerator at CERN in the tunnel originally built for the LEP accelerator that was closed in 2000. The cross-section of an LHC superconducting dipole magnet is also seen.

  15. La maquette digitale du tunnel du LEP

    CERN Document Server

    Brouns, G

    2000-01-01

    Pour l'installation du LHC et son équipement périphérique (ligne cryogénique, câbles, tuyauterie, etc.) dans le tunnel du LEP, une maquette digitale CAO doit être faite. Après un rappel de la définition théorique du tunnel du LEP, cette LHC project Note décrit comment sont utilisées et intégrées d'anciennes et de nouvelles mesures du tunnel pour arriver à un ensemble de données qui permettent de construire la maquette digitale (CAO) du tunnel du LHC. Ensuite, les résultats sont comparés à leur valeur théorique d'une part, et aux anciennes valeurs disponibles d'autre part.

  16. Many-electron tunneling in atoms

    CERN Document Server

    Zon, B A

    1999-01-01

    A theoretical derivation is given for the formula describing N-electron ionization of atom by a dc field and laser radiation in tunneling regime. Numerical examples are presented for noble gases atoms.

  17. Teelt van vruchtgewassen in lage tunnels

    NARCIS (Netherlands)

    Wijk, van C.A.P.; Geven, C.G.M.

    1994-01-01

    Een aantal warmteminnende vruchtgewassen zijn beproefd in lage tunnels en vergeleken met onbedekte teelt en met kasteelt. Het betrof aubergine, paprika, peper en diverse typen meloen. Daar is courgette als vergelijkend gewas aan toegevoegd

  18. Decoherence and tunneling of an interacting gas

    Science.gov (United States)

    Anglin, James; Rico-Perez, Luis; Wohlfarth, Daniel

    2015-05-01

    In quasi-steady escape of a confined interacting gas by quantum tunneling, collisional decoherence can reduce the escape rate through a many-body version of the Caldeira-Leggett effect. This explains why classical fluids fail to tunnel, even though they are composed of particles small enough to be quantum mechanical. We compute this effect in the Maxwell-Boltzmann regime by deriving a quantum generalization of the Boltzmann equation. We show that decoherence effectively makes tunneling of an interacting gas into an irreversible process: a uniquely quantum mechanical form of throttling. The rate of entropy production in tunneling is related in the semi-classical limit to the imaginary part of the single-particle action.

  19. A small cable tunnel inspection robot design

    Science.gov (United States)

    Zhou, Xiaolong; Guo, Xiaoxue; Huang, Jiangcheng; Xiao, Jie

    2017-04-01

    Modern city mainly rely on internal electricity cable tunnel, this can reduce the influence of high voltage over-head lines of urban city appearance and function. In order to reduce the dangers of cable tunnel artificial inspection and high labor intensity, we design a small caterpillar chassis in combination with two degrees of freedom robot with two degrees of freedom camera pan and tilt, used in the cable tunnel inspection work. Caterpillar chassis adopts simple return roller, damping structure. Mechanical arm with three parallel shafts, finish the up and down and rotated action. Two degrees of freedom camera pan and tilt are used to monitor cable tunnel with 360 °no dead angle. It looks simple, practical and efficient.

  20. 7 x 10 Foot Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — This wind tunnel is used for basic and applied research in aeromechanics on advanced and unique technology rotorcraft. It supports research on advanced concepts and...

  1. Dynamical quenching of tunneling in molecular magnets

    Energy Technology Data Exchange (ETDEWEB)

    José Santander, María, E-mail: maria.jose.noemi@gmail.com [Recursos Educativos Quántica, Santiago (Chile); Departamento de Física, Universidad de Santiago de Chile and CEDENNA, Avda. Ecuador 3493, Santiago (Chile); Nunez, Alvaro S., E-mail: alnunez@dfi.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago (Chile); Roldán-Molina, A. [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Avenida Universidad 330, Curauma, Valparaíso (Chile); Troncoso, Roberto E., E-mail: r.troncoso.c@gmail.com [Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Avda. Ecuador 3493, Santiago 9170124 (Chile); Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso (Chile)

    2015-12-15

    It is shown that a single molecular magnet placed in a rapidly oscillating magnetic field displays the phenomenon of quenching of tunneling processes. The results open a way to manipulate the quantum states of molecular magnets by means of radiation in the terahertz range. Our analysis separates the time evolution into slow and fast components thereby obtaining an effective theory for the slow dynamics. This effective theory presents quenching of the tunnel effect, in particular, stands out its difference with the so-called coherent destruction of tunneling. We support our prediction with numerical evidence based on an exact solution of Schrödinger's equation. - Highlights: • Single molecular magnets under rapidly oscillating magnetic fields is studied. • It is shown that this system displays the quenching of tunneling processes. • Our findings provide a control of quantum molecular magnets via terahertz radiation.

  2. LEP sees the end of the tunnel

    CERN Document Server

    2002-01-01

    After 14 months, which have seen the removal of 30,000 tonnes of material from the tunnel, the LEP dismantling operation has now been completed. LHC installation, which will be subject to new safety rules, can go ahead.

  3. Tertiary interactions within the ribosomal exit tunnel.

    Science.gov (United States)

    Kosolapov, Andrey; Deutsch, Carol

    2009-04-01

    Although tertiary folding of whole protein domains is prohibited by the cramped dimensions of the ribosomal tunnel, dynamic tertiary interactions may permit folding of small elementary units within the tunnel. To probe this possibility, we used a beta-hairpin and an alpha-helical hairpin from the cytosolic N terminus of a voltage-gated potassium channel and determined a probability of folding for each at defined locations inside and outside the tunnel. Minimalist tertiary structures can form near the exit port of the tunnel, a region that provides an entropic window for initial exploration of local peptide conformations. Tertiary subdomains of the nascent peptide fold sequentially, but not independently, during translation. These studies offer an approach for diagnosing the molecular basis for folding defects that lead to protein malfunction and provide insight into the role of the ribosome during early potassium channel biogenesis.

  4. Observing Quantum Tunneling in Perturbation Series

    CERN Document Server

    Suzuki, H; Suzuki, Hiroshi; Yasuta, Hirofumi

    1996-01-01

    We apply Borel resummation method to the conventional perturbation series of ground state energy in a metastable potential, $V(x)=x^2/2-gx^4/4$. We observe numerically that the discontinuity of Borel transform reproduces the imaginary part of energy eigenvalue, i.e., total decay width due to the quantum tunneling. The agreement with the exact numerical value is remarkable in the whole tunneling regime $0

  5. Low Power Band to Band Tunnel Transistors

    Science.gov (United States)

    2010-12-15

    the E-field and tunneling at the source- pocket junction you form a parasitic NPN + transistor and the injection mechanism of carriers into the...hypothesis that the 1000 ° C, 5s anneal split lead to a very wide pocket and the accidental formation of a NPN + transistor , while the 1000 ° C, 1s anneal...Low Power Band to Band Tunnel Transistors Anupama Bowonder Electrical Engineering and Computer Sciences University of California at Berkeley

  6. Geology of Pletovarje motorway tunnel (Slovenia

    Directory of Open Access Journals (Sweden)

    Magda Čarman

    2009-06-01

    Full Text Available Styrian motorway crosses the Pletovarje ridge through the tunnel having the same name. It intersects the mosteastern extension of the Southern Karavanke tectonic unit. Considering geological conditions, the tunnel couldbe divided into three sections: the inner Donat / Dona~ka fault zone composed of tectonic lenses of differentlithostratigraphic units (of paleozoic, triassic and tertiary age, massive dolomite (lower triassic and Smrekovecseries of oligocene age. Main faults have east – west direction and are subvertical.

  7. Numerical modeling of tunneling-induced seismicity

    Science.gov (United States)

    Rinaldi, Antonio Pio; Urpi, Luca

    2017-04-01

    Removal of rock mass in mining environment has been associated since long-time with seismic event of magnitude 3 and above, with the potential to cause damage to the infrastructures or even loss of human life. Although with similarities with mining, relatively unknown up to now are seismic events induced by tunneling. However with modern mechanized tunneling techniques, making possible to digging deeper and longer underground infrastructure, the risk is not negligible. As an example, the excavation of the 57km long Gotthard Base Tunnel has been associated more than hundred seismic events, with the largest one having magnitude of ML 2.4, damaging the tunnel infrastructures. For future scenario of deep geological storage of nuclear waste, tunneling will constitute the primary activity during site construction. Hence, it will be crucial to understand the risk associated with the underground construction operation that can reactivate seismogenic features nearby the future location of emplacement tunnels. Here we present numerical simulation aimed at understanding the potential for inducing seismicity during tunnel construction. The stress changes and their evolution during the excavation are evaluated with a finite element solver (FLAC3d). A strain-softening friction model is then used to simulate the occurrence of a sudden slip on a fault zone (if critical conditions for reactivation are reached). We also present a sensitivity analysis of the potential for inducing different seismic events by different tunnel sizes at varying distance from a nearby failure plane, with the final purpose of evaluating safety of a potential nuclear repository site on the short- and long-term.

  8. Aeroelastic instability stoppers for wind tunnel models

    Science.gov (United States)

    Doggett, R. V., Jr.; Ricketts, R. H. (Inventor)

    1981-01-01

    A mechanism for constraining models or sections thereof, was wind tunnel tested, deployed at the onset of aeroelastic instability, to forestall destructive vibrations in the model is described. The mechanism includes a pair of arms pivoted to the tunnel wall and straddling the model. Rollers on the ends of the arms contact the model, and are pulled together against the model by a spring stretched between the arms. An actuator mechanism swings the arms into place and back as desired.

  9. Radio-frequency scanning tunnelling microscopy.

    Science.gov (United States)

    Kemiktarak, U; Ndukum, T; Schwab, K C; Ekinci, K L

    2007-11-01

    The scanning tunnelling microscope (STM) relies on localized electron tunnelling between a sharp probe tip and a conducting sample to attain atomic-scale spatial resolution. In the 25-year period since its invention, the STM has helped uncover a wealth of phenomena in diverse physical systems--ranging from semiconductors to superconductors to atomic and molecular nanosystems. A severe limitation in scanning tunnelling microscopy is the low temporal resolution, originating from the diminished high-frequency response of the tunnel current readout circuitry. Here we overcome this limitation by measuring the reflection from a resonant inductor-capacitor circuit in which the tunnel junction is embedded, and demonstrate electronic bandwidths as high as 10 MHz. This approximately 100-fold bandwidth improvement on the state of the art translates into fast surface topography as well as delicate measurements in mesoscopic electronics and mechanics. Broadband noise measurements across the tunnel junction using this radio-frequency STM have allowed us to perform thermometry at the nanometre scale. Furthermore, we have detected high-frequency mechanical motion with a sensitivity approaching approximately 15 fm Hz(-1/2). This sensitivity is on par with the highest available from nanoscale optical and electrical displacement detection techniques, and the radio-frequency STM is expected to be capable of quantum-limited position measurements.

  10. Description of the vortex formation on a Savonius rotor in a water channel; Description de l`alternance des tourbillons d`un rotor Savonius par visualisation en tunnel hydrodynamique

    Energy Technology Data Exchange (ETDEWEB)

    Benghrib, D.; Ahram, A. [Universite Choiaib-Doukkali, Faculte des Sciences, El Jadida (Morocco); Bchir, L. [Universite Cadi-Ayyad, Faculte des Sciences Samlalia, Marrakech (Morocco)

    1998-08-01

    We study the vortex formation of a Savonius rotor `propulsive` blade. Particularly we describe the different events happening during a half period of rotation by means of chrono-photography technics. A film has been registered from visualisation in a water channel with the dye emitted from the centre of the rotor. The rotor blade is in plexiglas and we have been able to detect the different fluid motions on each side of the curved propulsive blade. (authors) 12 refs.

  11. Study on calculation of rock pressure for ultra-shallow tunnel in poor surrounding rock and its tunneling procedure

    Institute of Scientific and Technical Information of China (English)

    Xiaojun Zhou; Jinghe Wang; Bentao Lin

    2014-01-01

    A computational method of rock pressure applied to an ultra-shallow tunnel is presented by key block theory, and its mathematical formula is proposed according to a mechanical tunnel model with super-shallow depth. Theoretical analysis shows that the tunnel is subject to asymmetric rock pressure due to oblique topography. The rock pressure applied to the tunnel crown and sidewall is closely related to the surrounding rock bulk density, tunnel size, depth and angle of oblique ground slope. The rock pressure applied to the tunnel crown is much greater than that to the sidewalls, and the load applied to the left side-wall is also greater than that to the right sidewall. Mean-while, the safety of the lining for an ultra-shallow tunnel in strata with inclined surface is affected by rock pressure and tunnel support parameters. Steel pipe grouting from ground surface is used to consolidate the unfavorable surrounding rock before tunnel excavation, and the reinforcing scope is proposed according to the analysis of the asymmetric load induced by tunnel excavation in weak rock with inclined ground surface. The tunneling procedure of bench cut method with pipe roof protection is still discussed and carried out in this paper according to the special geological condition. The method and tunneling procedure have been successfully utilized to design and drive a real expressway tunnel. The practice in building the super-shallow tunnel has proved the feasibility of the calculation method and tunneling procedure presented in this paper.

  12. Tunneling and Transport in Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, Allen M. [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-08-16

    The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO3. The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

  13. Organic tunnel field effect transistors

    KAUST Repository

    Tietze, Max Lutz

    2017-06-29

    Various examples are provided for organic tunnel field effect transistors (OTFET), and methods thereof. In one example, an OTFET includes a first intrinsic layer (i-layer) of organic semiconductor material disposed over a gate insulating layer; source (or drain) contact stacks disposed on portions of the first i-layer; a second i-layer of organic semiconductor material disposed on the first i-layer surrounding the source (or drain) contact stacks; an n-doped organic semiconductor layer disposed on the second i-layer; and a drain (or source) contact layer disposed on the n-doped organic semiconductor layer. The source (or drain) contact stacks can include a p-doped injection layer, a source (or drain) contact layer, and a contact insulating layer. In another example, a method includes disposing a first i-layer over a gate insulating layer; forming source or drain contact stacks; and disposing a second i-layer, an n-doped organic semiconductor layer, and a drain or source contact.

  14. Tunneling and Transport in Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, Allen M. [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-08-16

    The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO3. The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

  15. Le LHC, un tunnel cosmique

    CERN Document Server

    CERN. Geneva

    2009-01-01

    Et si la lumière au bout du tunnel du LHC était cosmique ? En d’autres termes, qu’est-ce que le LHC peut nous apporter dans la connaissance de l’Univers ? Car la montée en énergie des accélérateurs de particules nous permet de mieux appréhender l’univers primordial, chaud et dense. Mais dans quel sens dit-on que le LHC reproduit des conditions proches du Big bang ? Quelles informations nous apporte-t-il sur le contenu de l’Univers ? La matière noire est-elle détectable au LHC ? L’énergie noire ? Pourquoi l’antimatière accumulée au CERN est-elle si rare dans l’Univers ? Et si le CERN a bâti sa réputation sur l’exploration des forces faibles et fortes qui opèrent au sein des atomes et de leurs noyaux, est-ce que le LHC peut nous apporter des informations sur la force gravitationnelle qui gouverne l’évolution cosmique ? Depuis une trentaine d’années, notre compréhension de l’univers dans ses plus grandes dimensions et l’appréhension de son comportement aux plus peti...

  16. [Carpal tunnel syndrome in acromegaly--4-case report and review of literature].

    Science.gov (United States)

    Imamura, H; Isu, T; Iwasaki, Y; Sugimoto, S; Abe, H; Tashiro, K

    1989-09-01

    Four cases of carpal tunnel syndrome in acromegaly were reported. These 4 cases were found in 21 acromegalies (19%). Besides change of features, they complained bilateral sensory disturbances of their hands. After transsphenoidal removal of pituitary adenoma, GH levels returned to the normal range and sensory disturbances were improved in all cases. Mechanism of carpal tunnel syndrome in acromegaly is that edematous synovial tissues compress the median nerve because oversecretion of growth hormone causes increase of sodium and water retention in the extracellular fluid. The patient who showes high basal level of growth hormone and/or acromegalic pattern by various tolerance tests does not always have the carpal tunnel syndrome. But this syndrome is apt to be found in active acromegaly. So the detection of the symptom showed by this activity such as hypersudation in our cases leads to the early diagnosis of acromegaly.

  17. A Method for Dynamic Risk Assessment and Management of Rockbursts in Drill and Blast Tunnels

    Science.gov (United States)

    Liu, Guo-Feng; Feng, Xia-Ting; Feng, Guang-Liang; Chen, Bing-Rui; Chen, Dong-Fang; Duan, Shu-Qian

    2016-08-01

    Focusing on the problems caused by rockburst hazards in deep tunnels, such as casualties, damage to construction equipment and facilities, construction schedule delays, and project cost increase, this research attempts to present a methodology for dynamic risk assessment and management of rockbursts in D&B tunnels. The basic idea of dynamic risk assessment and management of rockbursts is determined, and methods associated with each step in the rockburst risk assessment and management process are given, respectively. Among them, the main parts include a microseismic method for early warning the occurrence probability of rockburst risk, an estimation method that aims to assess potential consequences of rockburst risk, an evaluation method that utilizes a new quantitative index considering both occurrence probability and consequences for determining the level of rockburst risk, and the dynamic updating. Specifically, this research briefly describes the referenced microseismic method of warning rockburst, but focuses on the analysis of consequences and associated risk assessment and management of rockburst. Using the proposed method of risk assessment and management of rockburst, the occurrence probability, potential consequences, and the level of rockburst risk can be obtained in real-time during tunnel excavation, which contributes to the dynamic optimisation of risk mitigation measures and their application. The applicability of the proposed method has been verified by those cases from the Jinping II deep headrace and water drainage tunnels at depths of 1900-2525 m (with a length of 11.6 km in total for D&B tunnels).

  18. Study on Fluid-Lining-Rock Coupling Interaction of Diversion Tunnel under Seismic Load

    Directory of Open Access Journals (Sweden)

    Jian Deng

    2015-01-01

    Full Text Available Fluid-lining-rock coupling interaction of diversion tunnel under seismic load is a critical problem in seismic research which should be solved urgently. Based on the explicit finite element method for dynamic analysis of single-phase fluid and solid medium and combining with the boundary conditions of coupling interface, a dynamic explicit finite element solving format of diversion tunnel considering fluid-lining coupling interaction is established. In light of the basic theory of dynamic contact force method and applying the nonlinear hyperbolic constitutive model of contact surface, a dynamic explicit finite element time-domain integral equation of combined bearing of lining and surrounding rocks, which takes the bond-slip behavior of the contact surface into account, is put forward. Meanwhile, considering the dynamic interaction process of inner water and lining, lining and surrounding rocks, an explicit finite element numerical simulation analysis method of fluid-lining-rock coupling interaction of diversion tunnel under seismic load is presented. The calculation results of case study reasonably reflect the seismic response characteristics of diversion tunnel, and an effective analysis method is provided for the aseismic design of hydraulic tunnel.

  19. European Tunnelling Review Quality, Environment and Safety Focus

    Institute of Scientific and Technical Information of China (English)

    Bill Weburn

    2004-01-01

    This paper provides an overview of tunnelling projects with some of the themes covered by the Chengdu Tunnelling Conference.(a) Environmental issues and tunnels under high groundwater pressure (Hallandsis Rail Tunnel, Sweden)(b) Fire -fighting and tunnel safety on long highway tunnels (Socatop Tunnel, West Paris)(c) Mechanised tunnelling below the world's largest airport (Heathrow T5) of a quality that avoids disruption to its operation.Each of these overviews show an enhanced performance in regard to project specific events or objectives. Particularly in tunnelling, project owners expect more than just a facility delivered on time for their money: they expect an all round performance respecting deadlines, budget, environmental protection, safety, quality and community harmony. Funding agencies do not always have the same agenda as project owners, acknowledging peripheral selection criteria but often demanding that the lowest bidder be awarded work. All round performance requires all round project selection criteria.

  20. Mitigation of the surficial hydrogeological impact induced by the construction of the Pajares Tunnels (NW Spain).

    Science.gov (United States)

    Valenzuela, Pablo; Sáenz de Santa María, José Antonio; José Domínguez-Cuesta, María; López Fernández, Carlos; Meléndez-Asensio, Mónica; Jiménez-Sánchez, Montserrat

    2016-04-01

    Pajares Tunnels are railway tunnels 24.5 km long and 700 m depth drilled in Paleozoic rocks of the Cantabrian Range (NW Spain). The construction of these tunnels is the cause of a very important surficial hydrogeological impact on the Alcedo Valley consisting on: i) the strong alteration of its natural hydrogeological regime; ii) the development of 25 sinkholes from 2007 to 2014 in calcareous rocks covered by alluvial deposits; iii) the transformation of the Alcedo stream into an influent, losing all the surficial water flow by infiltration trough 7 active ponors developed at the stream bed. The estimated mean water volume infiltration across these sinkholes was around 0.4 Hm3/year (10 ls-1). Previous studies proved the infiltration of this runoff towards the new base level established by the tunnels, which would affect the operation and safety conditions required in a high-speed railway line. In order to minimize this situation, several geotechnical works have been performed from July 2014 to November 2015. These works consist on: (i) geological research, (ii) borehole drilling, (iii) geophysical prospecting, (iv) sealing of sinkholes and ponors, (v) construction of a concrete channel covered with geotextile and completely buried with original removed alluvial materials, and (vi) environmental restoration. After the completion of these actions, the first observations have allowed to note a total elimination of the infiltration from the Alcedo Valley to the tunnels. This involves an 8% reduction of total drainage in Pajares Tunnels (from average 350 l s-1 to 325 l s-1).

  1. Development of the tunneling junction simulation environment for scanning tunneling microscope evaluation

    Science.gov (United States)

    Gajewski, Krzysztof; Piasecki, Tomasz; Kopiec, Daniel; Gotszalk, Teodor

    2017-03-01

    Proper configuration of scanning tunneling microscope electronics plays an important role in the atomic scale resolution surface imaging. Device evaluation in the tunneling contact between scanning tip and sample may be prone to the surface quality or mechanical disturbances. Thus the use of tunneling junction simulator makes electronics testing more reliable and increases its repeatability. Here, we present the theoretical background enabling the proper selection of electronic components circuitry used as a tunneling junction simulator. We also show how to simulate mechanics related to the piezoelectric scanner, which is applied in real experiments. Practical use of the proposed simulator and its application in metrological characterization of the developed scanning tunneling microscope is also shown.

  2. Key technologies and risk management of deep tunnel construction at Jinping II hydropower station

    Institute of Scientific and Technical Information of China (English)

    Chunsheng Zhang; Ning Liu; Weijiang Chu

    2016-01-01

    The four diversion tunnels at Jinping II hydropower station represent the deepest underground project yet conducted in China, with an overburden depth of 1500e2000 m and a maximum depth of 2525 m. The tunnel structure was subjected to a maximum external water pressure of 10.22 MPa and the maximum single-point groundwater inflow of 7.3 m3/s. The success of the project construction was related to numerous challenging issues such as the stability of the rock mass surrounding the deep tunnels, strong rockburst prevention and control, and the treatment of high-pressure, large-volume groundwater infiltration. During the construction period, a series of new technologies was developed for the purpose of risk control in the deep tunnel project. Nondestructive sampling and in-situ measurement technologies were employed to fully characterize the formation and development of excavation damaged zones (EDZs), and to evaluate the mechanical behaviors of deep rocks. The time effect of marble fracture propagation, the brittleeductileeplastic transition of marble, and the temporal development of rock mass fracture and damage induced by high geostress were characterized. The safe construction of deep tunnels was achieved under a high risk of strong rockburst using active measures, a support system comprised of lining, grouting, and external water pressure reduction techniques that addressed the coupled effect of high geostress, high external water pressure, and a comprehensive early-warning system. A complete set of technologies for the treatment of high-pressure and large-volume ground-water infiltration was developed. Monitoring results indicated that the Jinping II hydropower station has been generally stable since it was put into operation in 2014.

  3. Determination of the effectiveness of concentrating mine-tunneling operations

    Energy Technology Data Exchange (ETDEWEB)

    Domanov, P.I.

    1979-02-01

    Experimental operations were conducted in 163 tunneling faces equipped with loading machines and mounted drilling machines and in 110 faces equipped with the pneumatic drilling machines 1PNB-2E in order to determine the optimal specific population of tunnellers in a working face. Following computerized processing of the obtained data, mathematical formulas were derived to compute the optimal rate of tunneling drifts with respect to productivity. Relationships were given for the productivity of drift miners and the rate of tunneling drifts, and between the complete cost of tunneling a drift and the velocity of tunneling. 3 figures.

  4. Co-current air-water flow in downward sloping pipes: Transport of capacity reducing gas pockets in wastewater mains

    NARCIS (Netherlands)

    Pothof, I.W.M.

    2011-01-01

    Air-water flow is an undesired condition in many systems for the transportation of water or wastewater. Air in storm water tunnels may get trapped and negatively affect the system. Air pockets in hydropower tunnels or sewers may cause blow-back events and inadmissible pressure spikes. Water pipes an

  5. Performance Analysis of VOIP over GRE Tunnel

    Directory of Open Access Journals (Sweden)

    Aria. Asadi Eskandar

    2015-11-01

    Full Text Available Voice over IP (VoIP is commonly known as phone service over the Internet. Any service using public IP network requires certain extent of security. Demand for security in VOIP technology is increasing. VPN is one of the commonly used methods to secure VOIP traffic. In this paper we simulated behavior of a VOIP communication while running over a GRE VPN Tunnel using OPNET Modeler 17.5. During the simulation, such performance parameters as: choice of voice signaling protocol, voice Codec, parameters arising from network QoS (in this study, homogenous vs. heterogeneous network environment and type of VPN tunneling protocol, were examined. We evaluated performance of VOIP communications in homogenous and heterogeneous network environments, configured based on two different signaling protocols, namely H.323 and SIP. Also, G.711 and G.723 were configured and tested as the choice for voice Codecs. GRE was implemented as the tunneling protocol. Result analysis of this study indicated that GRE Tunnel didn't show a significant increase in such call quality of service (QoS performance factors as: end-to-end delay, call setup time, or a decrease in call MOS value. Even though in a non-ideal (heterogeneous network environment, call quality of service (QoS performance factors shoed poor results; however, there was no significant evidence to suggest that GRE Tunnel is the root cause for such poor results.

  6. Tunnel Field-Effect Transistor with Epitaxially Grown Tunnel Junction Fabricated by Source/Drain-First and Tunnel-Junction-Last Processes

    Science.gov (United States)

    Morita, Yukinori; Mori, Takahiro; Migita, Shinji; Mizubayashi, Wataru; Tanabe, Akihito; Fukuda, Koichi; Masahara, Meishoku; Ota, Hiroyuki

    2013-04-01

    We fabricate p- and n-channel Si tunnel field-effect transistors (TFETs) with an epitaxially grown tunnel junction. In a novel source/drain-first and tunnel-junction-last fabrication process, a thin epitaxial undoped Si channel (epichannel) is deposited on a preferentially fabricated p- or n-type source area. The epichannel sandwiched by a gate insulator and a highly doped source well acts as a parallel-plate tunnel capacitor, which effectively multiplies drain current with an enlarged tunnel area. On the basis of its simple structure and easy fabrication, symmetric n- and p-transistor and complementary metal oxide semiconductor inverter operations were successfully demonstrated.

  7. Application of Doppler global velocimetry in cryogenic wind tunnels

    Science.gov (United States)

    Willert, C.; Stockhausen, G.; Beversdorff, M.; Klinner, J.; Lempereur, C.; Barricau, P.; Quest, J.; Jansen, U.

    2005-08-01

    A specially designed Doppler global velocimetry system (DGV, planar Doppler velocimetry) was developed and installed in a high-speed cryogenic wind tunnel facility for use at free stream Mach numbers between 0.2 and 0.88, and pressures between 1.2 bar and 3.3 bar. Particle seeding was achieved by injecting a mixture of gaseous nitrogen and water vapor into the dry and cold tunnel flow, which then immediately formed a large amount of small ice crystals. Given the limited physical and optical access for this facility, DGV is considered the best choice for non-intrusive flow field measurements. A multiple branch fiber imaging bundle attached to a common DGV image receiving system simultaneously viewed a common area in the flow field from three different directions through the wind tunnel side walls. The complete imaging system and fiber-fed light sheet generators were installed inside the normally inaccessible pressure plenum surrounding the wind tunnel’s test section. The system control and frequency-stabilized laser system were placed outside of the pressure shell. With a field of view of 300×300 mm2, the DGV system acquired flow maps at a spatial resolution of 3×3 mm2 in the wake of simple vortex generators as well as in the wake of different wing-tip devices on a half-span aircraft model. Although problems mainly relating to light reflections and icing on the observation windows significantly impaired part of the measurements, the remotely controlled hardware operated reliably over the course of three months.

  8. Construction of a highway tunnel with TBM. ; No. 2 Yuda tunnel of Akita motorway. TBM ni yoru doro tonneru no seko. ; Akita jidoshado Yuda daini tonneru

    Energy Technology Data Exchange (ETDEWEB)

    Miura, M. (Obayashi Corp., Osaka (Japan))

    1993-12-25

    The tunnel excavator TBM has an ability of executing excavation works rapidly and is attractive for excavating speedily and efficiently a tunnel which has a trend to be larger in cross section and longer in length in the future. In order to study possibility and workability of the excavation techniques using this TBM, TBM has been adopted for excavating No.2 Yuda tunnel of Akita motorway. It is the technique to execute an excavation work of a top heading with a TBM whose diameter is 3.5m, then to expand the heading by cutting the earth to a predetermined cross section through the total cross sectional excavation technique with an auxiliary bench. The total length of the tunnel is 2,413m. The temperature in the winter is low, snowfall is heavy and rocks are volcanic. In planning the usage of TBM, it has been considered to design and build a TBM capable of digging the soft earth, not to let the TBM caught by the expansive earth, to be able to take muck out even in case of voluminous gushing water and to grasp the earth in front quickly and exactly. Also an automatic operation system has been adopted taking into consideration that no individual difference of operator would be reflected and manpower saving would be expected in the future. 7 figs., 1 tab.

  9. Overview of traffic safety aspects and design in road tunnels

    Directory of Open Access Journals (Sweden)

    Shy Bassan

    2016-07-01

    Drivers in road tunnels generally reduce their speed and increase their lateral position from the right tunnel wall while driving. In shorter tunnels, with reduced driving speed, driver vigilance may be more robust without being hindered by dull driving, which is more common in longer tunnels. Still, in spite of driver alertness, crash rates in tunnels occur due to the tunnel's unusual driving environment. Crash rates are lower in the tunnel inner zone due to driver alertness, especially after passing the transition zone and acclimating to the tunnel environment. The number of crashes, however, is higher along zone 4 (tunnel inner zone, which is the principal zone, as it covers longer driving distance. According to most studies, short tunnels were found to exhibit higher crash rates than long tunnels because the entrance zones incorporate higher crash rates, compared with the midzones; nonetheless, longer unidirectional (freeway and multilane tunnels with higher design speed, entail lower driver alertness and diminished concentration due to relatively monotonous driving in spite of a tunnel's closed environment.

  10. Suppression of water as a nucleophile in Candida antarctica lipase B catalysis

    DEFF Research Database (Denmark)

    Larsen, Marianne Wittrup; Zielinska, Dorota F; Martinelle, Mats

    2010-01-01

    A water tunnel in Candida antarctica lipase B that provides the active site with substrate water is hypothesized. A small, focused library created in order to prevent water from entering the active site through the tunnel was screened for increased transacylation over hydrolysis activity. A single...

  11. Hydrogeologic setting and simulation of groundwater flow near the Canterbury and Leadville Mine Drainage Tunnels, Leadville, Colorado

    Science.gov (United States)

    Wellman, Tristan P.; Paschke, Suzanne S.; Minsley, Burke; Dupree, Jean A.

    2011-01-01

    The Leadville mining district is historically one of the most heavily mined regions in the world producing large quantities of gold, silver, lead, zinc, copper, and manganese since the 1860s. A multidisciplinary investigation was conducted by the U.S. Geological Survey, in cooperation with the Colorado Department of Public Health and Environment, to characterize large-scale groundwater flow in a 13 square-kilometer region encompassing the Canterbury Tunnel and the Leadville Mine Drainage Tunnel near Leadville, Colorado. The primary objective of the investigation was to evaluate whether a substantial hydraulic connection is present between the Canterbury Tunnel and Leadville Mine Drainage Tunnel for current (2008) hydrologic conditions. Altitude in the Leadville area ranges from about 3,018 m (9,900 ft) along the Arkansas River valley to about 4,270 m (14,000 ft) along the Continental Divide east of Leadville, and the high altitude of the area results in a moderate subpolar climate. Winter precipitation as snow was about three times greater than summer precipitation as rain, and in general, both winter and summer precipitation were greatest at higher altitudes. Winter and summer precipitation have increased since 2002 coinciding with the observed water-level rise near the Leadville Mine Drainage Tunnel that began in 2003. The weather patterns and hydrology exhibit strong seasonality with an annual cycle of cold winters with large snowfall, followed by spring snowmelt, runoff, and recharge (high-flow) conditions, and then base-flow (low-flow) conditions in the fall prior to the next winter. Groundwater occurs in the Paleozoic and Precambrian fractured-rock aquifers and in a Quaternary alluvial aquifer along the East Fork Arkansas River, and groundwater levels also exhibit seasonal, although delayed, patterns in response to the annual hydrologic cycle. A three-dimensional digital representation of the extensively faulted bedrock was developed and a geophysical direct

  12. On the formation of the tunnel valleys of the southern Laurentide ice sheet

    Science.gov (United States)

    Hooke, R. LeB; Jennings, C.E.

    2006-01-01

    Catastrophic releases of meltwater, produced by basal melting and stored for decades in subglacial reservoirs at high pressure, may have been responsible for eroding the broad, deep tunnel valleys that are common along the margins of some lobes of the southern Laurentide ice sheet. We surmise that these releases began when the high water pressure was transmitted to the margin through the substrate. The water pressure in the substrate at the margin would then have been significantly above the overburden pressure, leading to sapping failure. Headward erosion of a conduit in the substrate (piping) could then tap the stored water, resulting in the outburst. In some situations, development of a siphon may have lowered the reservoir below its overflow level, thus tapping additional water. Following the flood, the seal could have reformed and the reservoir refilled, setting up conditions for another outburst. Order of magnitude calculations suggest that once emptied, a subglacial reservoir could refill in a matter of decades. The amount of water released during several outbursts appears to be sufficient to erode a tunnel valley. We think that tunnel valleys are most likely to have formed in this way where and when the glacier margin was frozen to the bed and permafrost extended from the glacier forefield several kilometers back under the glacier, as reservoirs would then have been larger and more common, and the seal more robust and more likely to reform after an outburst. ?? 2006 Elsevier Ltd. All rights reserved.

  13. Fractal Prediction of Grouting Volume for Treating Karst Caverns along a Shield Tunneling Alignment

    Directory of Open Access Journals (Sweden)

    Wen-Chieh Cheng

    2017-06-01

    Full Text Available Karst geology is common in China, and buried karst formations are widely distributed in Guangdong province. In the process of shield tunneling, the abundant water resources present in karst caverns could lead to the potential for high water ingress, and a subsequent in situ stress change-induced stratum collapse. The development and distribution of karst caverns should therefore be identified and investigated prior to shield tunnel construction. Grouting is an efficient measure to stabilize karst caverns. The total volume of karst caverns along the shield tunneling alignment, and its relationship with the required volume of grouts, should be evaluated in the preliminary design phase. Conventionally, the total volume of karst caverns is empirically estimated based on limited geological drilling hole data; however, accurate results are rarely obtained. This study investigates the hydrogeology and engineering geology of Guangzhou, the capital of Guangdong province, and determines the fractal characteristics of the karst caverns along the tunnel section of Guangzhou metro line no. 9. The karst grouting coefficients (VR were found to vary from 0.11 in the case of inadequate drilling holes to 1.1 in the case where adequate drilling holes are provided. A grouting design guideline was furthermore developed in this study for future projects in karst areas.

  14. Particle and chemical control using tunnel flow

    Energy Technology Data Exchange (ETDEWEB)

    Chilese, Frank; Delgado, Gildardo R.; Wack, Daniel; Torczynski, John R.

    2017-09-12

    An apparatus for contaminant control, having: a first optical assembly including: a first light homogenizer tunnel with: a first end connected to an extreme ultra-violet light source, a second end in communication with a destination chamber, a first enclosed space, and, a first gas input arranged to introduce a first gas such that the first gas flows in a first direction toward the first end and in a second direction toward the second end. The apparatus alternately having: a second optical assembly including: a second light homogenizer tunnel with: a third end connected to an extreme ultra-violet light source, a fourth end in communication with a destination chamber, a second enclosed space, a diffusion barrier tube including: a fifth end facing the fourth end and a sixth end in communication with a destination chamber, and a second gas input between the second light homogenizer tunnel and the diffusion tube.

  15. Quantum tunneling from paths in complex time

    CERN Document Server

    Bramberger, Sebastian F; Lehners, Jean-Luc

    2016-01-01

    We study quantum mechanical tunneling using complex solutions of the classical field equations. Simple visualization techniques allow us to unify and generalize previous treatments, and straightforwardly show the connection to the standard approach using Euclidean instanton solutions. We demonstrate that the negative modes of solutions along various contours in the complex time plane reveal which paths contribute to tunneling and which do not, and we provide a criterion for identifying the negative modes. Central to our approach is the solution of the background and perturbation equations not only along a single path, but over an extended region of the complex time plane. Our approach allows for a fully continuous and coherent treatment of classical evolution interspersed by quantum tunneling events, and is applicable in situations where singularities are present and also where Euclidean solutions might not exist.

  16. Multidimensional Quantum Tunneling in the Schwinger Effect

    CERN Document Server

    Dumlu, Cesim K

    2015-01-01

    We study the Schwinger effect, in which the external field having a spatio-temporal profile creates electron-positron pairs via multidimensional quantum tunneling. Our treatment is based on Gutzwiller's trace formula for the QED effective action, whose imaginary part is represented by a sum over complex wordlines. The worldlines are multi-periodic, and the periods of motion collectively depend on the strength of spatial and temporal inhomogeneity. We argue that Hamilton's characteristic function that leads to the correct tunneling amplitude must explicitly depend on both periods, and is represented by an average over the internal cycles of motion. We use this averaging method to calculate the pair production rate in an exponentially damped sinusoidal field, where we find that the initial conditions for each family of periodic trajectories lie on a curve in the momentum plane. The ratio of the periods, which may also be referred as the topological index, stays uniform on each curve. Calculation of tunneling am...

  17. Phonon tunneling through a double barrier system

    Energy Technology Data Exchange (ETDEWEB)

    Villegas, Diosdado [Departamento de Física, Universidad Central “Marta Abreu” de Las Villas, CP 54830, Santa Clara, Villa Clara (Cuba); Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico); León-Pérez, Fernando de [Centro Universitario de la Defensa de Zaragoza, Ctra. de Huesca s/n, E-50090 Zaragoza (Spain); Pérez-Álvarez, R. [Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca (Mexico); Arriaga, J., E-mail: arriaga@ifuap.buap.mx [Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico)

    2015-04-15

    The tunneling of optical and acoustic phonons at normal incidence on a double-barrier is studied in this paper. Transmission coefficients and resonance conditions are derived theoretically under the assumption that the long-wavelength approximation is valid. It is shown that the behavior of the transmission coefficients for the symmetric double barrier has a Lorentzian form close to resonant frequencies and that Breit–Wigner's formula have a general validity in one-dimensional phonon tunneling. Authors also study the so-called generalized Hartman effect in the tunneling of long-wavelength phonons and show that this effect is a numerical artifact resulting from taking the opaque limit before exploring the variation with a finite barrier width. This study could be useful for the design of acoustic devices.

  18. Isotope effects of hydrogen and atom tunnelling

    Science.gov (United States)

    Buchachenko, A. L.; Pliss, E. M.

    2016-06-01

    The abnormally high mass-dependent isotope effects in liquid-phase hydrogen (deuterium) atom transfer reactions, which are customarily regarded as quantum effects, are actually the products of two classical effects, namely, kinetic and thermodynamic ones. The former is determined by the rate constants for atom transfer and the latter is caused by nonbonded (or noncovalent) isotope effects in the solvation of protiated and deuterated reacting molecules. This product can mimic the large isotope effects that are usually attributed to tunnelling. In enzymatic reactions, tunnelling is of particular interest; its existence characterizes an enzyme as a rigid molecular machine in which the residence time of reactants on the reaction coordinate exceeds the waiting time for the tunnelling event. The magnitude of isotope effect becomes a characteristic parameter of the internal dynamics of the enzyme catalytic site. The bibliography includes 61 references.

  19. Electronic thermometry in tunable tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro

    2016-03-15

    A tunable tunnel junction thermometry circuit includes a variable width tunnel junction between a test object and a probe. The junction width is varied and a change in thermovoltage across the junction with respect to the change in distance across the junction is determined. Also, a change in biased current with respect to a change in distance across the junction is determined. A temperature gradient across the junction is determined based on a mathematical relationship between the temperature gradient, the change in thermovoltage with respect to distance and the change in biased current with respect to distance. Thermovoltage may be measured by nullifying a thermoelectric tunneling current with an applied voltage supply level. A piezoelectric actuator may modulate the probe, and thus the junction width, to vary thermovoltage and biased current across the junction. Lock-in amplifiers measure the derivatives of the thermovoltage and biased current modulated by varying junction width.

  20. Vibration Compensation for Scanning Tunneling Microscope

    Institute of Scientific and Technical Information of China (English)

    LI Meng-chao; FU Xing; WEI Xiao-lei; HU Xiao-tang

    2003-01-01

    The influence of vibration is already one of main obstacles for improving the nano measuring accuracy.The techniques of anti-vibration,vibration isolation and vibration compensation become an important branch in nano measuring field.Starting with the research of sensitivity to vibration of scanning tunneling microscope(STM),the theory,techniques and realization methods of nano vibration sensor based on tunnel effect are initially investigated,followed by developing the experimental devices.The experiments of the vibration detection and vibration compensation are carried out.The experimental results show that vibration sensor based on tunnel effect is characterized by high sensitivity,good frequency characteristic and the same vibratory response characteristic consistent with STM.

  1. Scanning Tunneling Spectroscope Use in Electrocatalysis Testing

    Science.gov (United States)

    Knutsen, Turid

    2010-01-01

    The relationship between the electrocatalytic properties of an electrode and its ability to transfer electrons between the electrode and a metallic tip in a scanning tunneling microscope (STM) is investigated. The alkaline oxygen evolution reaction (OER) was used as a test reaction with four different metallic glasses, Ni78Si8B14, Ni70Mo20Si5B5, Ni58Co20Si10B12, and Ni25Co50Si15B10, as electrodes. The electrocatalytic properties of the electrodes were determined. The electrode surfaces were then investigated with an STM. A clear relationship between the catalytic activity of an electrode toward the OER and its tunneling characteristics was found. The use of a scanning tunneling spectroscope (STS) in electrocatalytic testing may increase the efficiency of the optimization of electrochemical processes.

  2. Scanning Tunneling Spectroscope Use in Electrocatalysis Testing

    Directory of Open Access Journals (Sweden)

    Turid Knutsen

    2010-06-01

    Full Text Available The relationship between the electrocatalytic properties of an electrode and its ability to transfer electrons between the electrode and a metallic tip in a scanning tunneling microscope (STM is investigated. The alkaline oxygen evolution reaction (OER was used as a test reaction with four different metallic glasses, Ni78Si8B14, Ni70Mo20Si5B5, Ni58Co20Si10B12, and Ni25Co50Si15B10, as electrodes. The electrocatalytic properties of the electrodes were determined. The electrode surfaces were then investigated with an STM. A clear relationship between the catalytic activity of an electrode toward the OER and its tunneling characteristics was found. The use of a scanning tunneling spectroscope (STS in electrocatalytic testing may increase the efficiency of the optimization of electrochemical processes.

  3. Coupling quantum tunneling with cavity photons.

    Science.gov (United States)

    Cristofolini, Peter; Christmann, Gabriel; Tsintzos, Simeon I; Deligeorgis, George; Konstantinidis, George; Hatzopoulos, Zacharias; Savvidis, Pavlos G; Baumberg, Jeremy J

    2012-05-11

    Tunneling of electrons through a potential barrier is fundamental to chemical reactions, electronic transport in semiconductors and superconductors, magnetism, and devices such as terahertz oscillators. Whereas tunneling is typically controlled by electric fields, a completely different approach is to bind electrons into bosonic quasiparticles with a photonic component. Quasiparticles made of such light-matter microcavity polaritons have recently been demonstrated to Bose-condense into superfluids, whereas spatially separated Coulomb-bound electrons and holes possess strong dipole interactions. We use tunneling polaritons to connect these two realms, producing bosonic quasiparticles with static dipole moments. Our resulting three-state system yields dark polaritons analogous to those in atomic systems or optical waveguides, thereby offering new possibilities for electromagnetically induced transparency, room-temperature condensation, and adiabatic photon-to-electron transfer.

  4. Positioning systems for underground tunnel environments

    CERN Document Server

    Leite Pereira, Fernando; Theis, Christian

    In the last years the world has witnessed a remarkable change in the computing concept by entering the mobile era. Incredibly powerful smartphones have proliferated at stunning pace and tablet computers are capable of running demanding applications and meet new business requirements. Being wireless, localization has become crucial not only to serve individuals but also help companies in industrial and safety processes. In the context of the Radiation Protection group at CERN, automatic localization, besides allowing to find people, would help improving the radiation surveys performed regularly along the accelerator tunnels. The research presented in this thesis attempts to answer questions relatively to the viability of localization in a harsh conditions tunnel: “Is localization in a very long tunnel possible, meeting its restrictions and without incurring prohibitive costs and infrastructure?”, “Can one achieve meter-level accuracy with GSM deployed over leaky-feeder?”, “Is it possible to prototype...

  5. Electrodiagnostic approach to carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    Cherian Ajith

    2006-01-01

    Full Text Available An algorithm for an electrophysiological approach to carpal tunnel syndrome is proposed. This technical note takes into account the standard tests, comparison tests and needle electromyography. If the standard tests are negative, a comparison study can be done to identify cases of minimal or very mild carpal tunnel syndrome (CTS. If comparison studies are negative, CTS can be ruled out and a search for other causes have to be made. If the standard tests are positive, carpal tunnel syndrome can be divided into extreme, severe,moderate and mild cases. Motor comparison study is useful in extreme CTS cases. Needle electromyography is a must in all cases where the standard tests are positive. This streamlined approach allows accurate diagnosis with minimum essential tests.

  6. Key technologies and risk management of deep tunnel construction at Jinping II hydropower station

    Directory of Open Access Journals (Sweden)

    Chunsheng Zhang

    2016-08-01

    Full Text Available The four diversion tunnels at Jinping II hydropower station represent the deepest underground project yet conducted in China, with an overburden depth of 1500–2000 m and a maximum depth of 2525 m. The tunnel structure was subjected to a maximum external water pressure of 10.22 MPa and the maximum single-point groundwater inflow of 7.3 m3/s. The success of the project construction was related to numerous challenging issues such as the stability of the rock mass surrounding the deep tunnels, strong rockburst prevention and control, and the treatment of high-pressure, large-volume groundwater infiltration. During the construction period, a series of new technologies was developed for the purpose of risk control in the deep tunnel project. Nondestructive sampling and in-situ measurement technologies were employed to fully characterize the formation and development of excavation damaged zones (EDZs, and to evaluate the mechanical behaviors of deep rocks. The time effect of marble fracture propagation, the brittle–ductile–plastic transition of marble, and the temporal development of rock mass fracture and damage induced by high geostress were characterized. The safe construction of deep tunnels was achieved under a high risk of strong rockburst using active measures, a support system comprised of lining, grouting, and external water pressure reduction techniques that addressed the coupled effect of high geostress, high external water pressure, and a comprehensive early-warning system. A complete set of technologies for the treatment of high-pressure and large-volume groundwater infiltration was developed. Monitoring results indicated that the Jinping II hydropower station has been generally stable since it was put into operation in 2014.

  7. Quantum tunneling from high dimensional G\\"odel black hole

    CERN Document Server

    Li, Hui-Ling; Zu, Xiao-Tao

    2014-01-01

    Considering quantum gravity effect, we investigate the quantum tunneling from high dimensional Kerr-G\\"odel black hole using generalized Dirac equation. As a result, revised tunneling probability is obtained, and the corrected Hawking temperature is also presented.

  8. Carpal tunnel syndrome after 22 years of Colle's fracture

    Directory of Open Access Journals (Sweden)

    Goyal V

    2003-01-01

    Full Text Available Delayed carpal tunnel syndrome is rare. We describe the electrophysiological findings in a patient with Colle's fracture, who developed carpal tunnel syndrome 22 years after a wrist injury.

  9. Carpal tunnel syndrome: an unusual presentation of brachial hypertrophy.

    OpenAIRE

    Shenoy, K. T.; Saha, P. K.; Ravindran, M

    1980-01-01

    A patient with carpal tunnel syndrome in association with congenital hypertrophy of right upper limb is described. The median nerve also showed hypertrophy. The symptoms were relieved by decompression of the carpal tunnel.

  10. A Top Pilot Tunnel Preconditioning Method for the Prevention of Extremely Intense Rockbursts in Deep Tunnels Excavated by TBMs

    Science.gov (United States)

    Zhang, Chuanqing; Feng, Xiating; Zhou, Hui; Qiu, Shili; Wu, Wenping

    2012-05-01

    The headrace tunnels at the Jinping II Hydropower Station cross the Jinping Mountain with a maximum overburden depth of 2,525 m, where 80% of the strata along the tunnels consist of marble. A number of extremely intense rockbursts occurred during the excavation of the auxiliary tunnels and the drainage tunnel. In particular, a tunnel boring machine (TBM) was destroyed by an extremely intense rockburst in a 7.2-m-diameter drainage tunnel. Two of the four subsequent 12.4-m-diameter headrace tunnels will be excavated with larger size TBMs, where a high risk of extremely intense rockbursts exists. Herein, a top pilot tunnel preconditioning method is proposed to minimize this risk, in which a drilling and blasting method is first recommended for the top pilot tunnel excavation and support, and then the TBM excavation of the main tunnel is conducted. In order to evaluate the mechanical effectiveness of this method, numerical simulation analyses using the failure approaching index, energy release rate, and excess shear stress indices are carried out. Its construction feasibility is discussed as well. Moreover, a microseismic monitoring technique is used in the experimental tunnel section for the real-time monitoring of the microseismic activities of the rock mass in TBM excavation and for assessing the effect of the top pilot tunnel excavation in reducing the risk of rockbursts. This method is applied to two tunnel sections prone to extremely intense rockbursts and leads to a reduction in the risk of rockbursts in TBM excavation.

  11. Gauge-independence of tunneling rates

    CERN Document Server

    Plascencia, Alexis D

    2016-01-01

    It is shown that tunneling rates can be defined in terms of a false-vacuum effective action whose reality and convexity properties differ from those of the corresponding groundstate functional. The tunneling rate is directly related to the false-vacuum effective action evaluated at an extremal "quantum bounce". The Nielsen identities of the false-vacuum functional ensure that the rate remains independent of the choice of gauge-fixing. Our results are nonperturbative and clarify issues related with convexity and radiative corrections.

  12. Vibration measurement and modal analysis for tunneller

    Institute of Scientific and Technical Information of China (English)

    HUANG Min; WU Miao; WEI Ren-zhi

    2001-01-01

    In this paper, the method of vibration measurement and modal analysis for AM~50 Tunneller machine is presented. When the machine was used for cutting man-made coal bed and real coal bed, the vibration of the machine was measured and the results of signal analysis show that the vibration characteristics under the two kinds of working situations are similar. The modal model of the machine is established, and then, the intrinsic vibration characteristics of AM50 tunneller are investigated by means of the method of experimental modal analysis. The vibration response simulation under a set of loading spectra measured is carried out by force response simulation software.

  13. Resonant tunneling in graphene pseudomagnetic quantum dots.

    Science.gov (United States)

    Qi, Zenan; Bahamon, D A; Pereira, Vitor M; Park, Harold S; Campbell, D K; Neto, A H Castro

    2013-06-12

    Realistic relaxed configurations of triaxially strained graphene quantum dots are obtained from unbiased atomistic mechanical simulations. The local electronic structure and quantum transport characteristics of y-junctions based on such dots are studied, revealing that the quasi-uniform pseudomagnetic field induced by strain restricts transport to Landau level- and edge state-assisted resonant tunneling. Valley degeneracy is broken in the presence of an external field, allowing the selective filtering of the valley and chirality of the states assisting in the resonant tunneling. Asymmetric strain conditions can be explored to select the exit channel of the y-junction.

  14. Fire Resistant Panels for the Tunnel Linings

    Directory of Open Access Journals (Sweden)

    Gravit Marina

    2016-01-01

    Full Text Available Presents the results of studies of innovative materials in the field of experimental and theoretical research fire resistance fireproof panels Pyro-Safe Aestuver T. Owing to the assembly simplicity, materials cheapness, high ecological standard, recycling, reuse potential, are benefit. Research work is running to improve the knowledge about fireproof panels Pyro-Safe Aestuver T for tunnel lining, its basic performance, its long term behavior and in particular also its fire proof for example when used for the lining of road tunnels.

  15. Microscopic tunneling theory of long Josephson junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, N.; Hattel, Søren A.; Samuelsen, Mogens Rugholm

    1992-01-01

    We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate that the detai......We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate...

  16. Polaronic Tunnelling in Organic Triblock Copolymers

    Institute of Scientific and Technical Information of China (English)

    LIU De-Sheng; ZHANG Da-Cheng; XIE Shi-Jie; MEI Liang-Mo

    2005-01-01

    @@ Polaron tunnelling is studied in xPA/nPPP/xPA (PA for polyacetylene and PPP poly (p-phenylene)) triblock copolymer, which has a well-barrier-well structure. An extended tight-binding Hamiltonian including external electric field is adopted. Without electric field, the injected electrons would not extend over the whole copolymer chain but instead be confined in the segments of PA. This is different from the behaviour of the traditional semiconductors. It is found that the polaron can transfer to the potential barrier-PPP segment when the applied electric field reaches a certain value. The critical polaron tunnelling electric fields depend upon the lengths of PPP segments.

  17. Traceable long range scanning tunneling microscopy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Dimensionally correct and directly traceable measurement is not feasible with conventional scanning tunneling microscopy (STMs) due to severe hysteresis and non-linearity of the commonly applied piezo tube scanners and the very short range.By integrating a custom made probing system based on tunneling current measurement into a commercially available and laser-interferometrically position controlled positioning system, an STM with a principal measuring range of 25 mm×25 mm×5 mm and traceable position measurement has been set-up and tested.

  18. Wind Tunnel Measurements at LM Wind Power

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    2012-01-01

    This section presents the results obtained during the experimental campaign that was conducted in the wind tunnel at LM Wind Power in Lunderskov from August 16th to 26th, 2010. The goal of this study is to validate the so-called TNO trailing edge noise model through measurements of the boundary...... layer turbulence characteristics and the far-field noise generated by the acoustic scattering of the turbulent boundary layer vorticies as they convect past the trailing edge. This campaign was conducted with a NACA0015 airfoil section that was placed in the wind tunnel section. It is equipped with high...

  19. Prevalence of carpal tunnel syndrome in motorcyclists.

    Science.gov (United States)

    Manes, Harvey R

    2012-05-01

    Carpal tunnel syndrome is prevalent in patients who have a repetitive motion, vibration, or pressure exerted on the wrist joint for an extended period of time. The prevalence of this condition in the general population is approximately 5%. Motorcyclists subject themselves to high levels of vibration from the road and use their wrists to control the motorcycle's brakes, gas intake, and gears via the handlebars. Under these conditions, the author hypothesized that an increased prevalence of carpal tunnel syndrome would be observed in this population.

  20. Treatment of repetitive use carpal tunnel syndrome

    Science.gov (United States)

    Smith, Chadwick F.; Vangsness, C. Thomas; Anderson, Thomas; Good, Wayne

    1995-05-01

    In 1990, a randomized, double-blind study was initiated to evaluate the use of an eight-point conservative treatment program in carpal tunnel syndrome. A total of 160 patients were delineated with symptoms of carpal tunnel syndrome. These patients were then divided into two groups. Both groups were subjected to an ergonomically correct eight-point work modification program. A counterfeit low level laser therapy unit was utilized in Group A, while an actual low level laser therapy unit was utilized in Group B. The difference between Groups A and B was statistically significant in terms of return to work, conduction study improvement, and certain range of motion and strength studies.