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Sample records for 24-inch water tunnel

  1. A user's guide to the Langley 16- by 24-inch water tunnel

    NASA Technical Reports Server (NTRS)

    Pendergraft, Odis C., Jr.; Neuhart, Dan H.; Kariya, Timmy T.

    1992-01-01

    The Langley 16 x 24 inch Water Tunnel is described in detail, along with all the supporting equipment used in its operation as a flow visualization test facility. These include the laser and incandescent lighting systems; and the photographic, video, and laser fluorescence anemometer systems used to make permanent records of the test results. This facility is a closed return water tunnel capable of test section velocities from 0 to 0.75 feet per second with flow through the 16 x 24 inch test section in a downward (vertical) direction. The velocity normally used for testing is 0.25 feet per second where the most uniform flow occurs, and is slow enough to easily observe flow phenomena such as vortex flow with the unaided eye. An overview is given of the operational characteristics, procedures, and capabilities of the water tunnel to potential users of the facility so that they may determine if the facility meets their needs for a planned study.

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

    NASA Technical Reports Server (NTRS)

    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.

  3. 24 Inch Reusable Solid Rocket Motor Test

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A scaled-down 24-inch version of the Space Shuttle's Reusable Solid Rocket Motor was successfully fired for 21 seconds at a Marshall Space Flight Center (MSFC) Test Stand. The motor was tested to ensure a replacement material called Lycocel would meet the criteria set by the Shuttle's Solid Motor Project Office. The current material is a heat-resistant, rayon-based, carbon-cloth phenolic used as an insulating material for the motor's nozzle. Lycocel, a brand name for Tencel, is a cousin to rayon and is an exceptionally strong fiber made of wood pulp produced by a special 'solvent-spirning' process using a nontoxic solvent. It will also be impregnated with a phenolic resin. This new material is expected to perform better under the high temperatures experienced during launch. The next step will be to test the material on a 48-inch solid rocket motor. The test, which replicates launch conditions, is part of Shuttle's ongoing verification of components, materials, and manufacturing processes required by MSFC, which oversees the Reusable Solid Rocket Motor project. Manufactured by the ATK Thiokol Propulsion Division in Promontory, California, the Reusable Solid Rocket Motor measures 126 feet (38.4 meters) long and 12 feet (3.6 meters) in diameter. It is the largest solid rocket motor ever flown and the first designed for reuse. During its two-minute burn at liftoff, each motor generates an average thrust of 2.6 million pounds (1.2 million kilograms).

  4. A water tunnel study of Gurney flaps

    NASA Technical Reports Server (NTRS)

    Neuhart, Dan H.; Pendergraft, Odis C., Jr.

    1988-01-01

    Several Gurney flap configurations were tested in the NASA Langley 16 x 24 inch Water Tunnel. These devices provided an increased region of attached flow on a wing upper surface relative to the wing without the flaps. The recirculation region behind the flap was visualized and shown to be consistent with hypotheses stated in previous research. Although the test Reynolds number for this study was several orders of magnitude below those in previous investigations, the effect of the Gurney flaps is in qualitative agreement with them. This is as would be expected from first order effects for high lift devices.

  5. Project Waiver of American Iron and Steel Requirements to the Napa Sanitation District for 24-Inch Diameter Butterfly Valves

    EPA Pesticide Factsheets

    Waiver approval by EPA pursuant to the American Iron and Steel Requirements of the Clean Water Act Section 608 to the Napa Sanitation District in California for the purchase of 24-inch butterfly valves.

  6. Lowell Observatory's 24-inch Clark Refractor: Its History and Renovation

    NASA Astrophysics Data System (ADS)

    Schindler, Kevin; Nye, Ralph; Rosenthal, Peter

    2016-01-01

    In 1895, Percival Lowell hired eminent telescope maker Alvan G. Clark to build a 24-inch refractor. Lowell intended the telescope intitally for observing Mars in support of his controversial theories about life on that planet. Clark finished the telescope within a year and at a cost of $20,000. Lowell and his staff of assistants and astronomers began observing through it on July 23, 1896, setting off a long and productive career for the telescope.While Lowell's Mars studies dominated early work with the Clark, V.M. Slipher by the 1910s was using it to observe planetary rotations and atmospheric compositions. He soon revolutionized spectroscopic studies, gathering excruciatingly long spectra - some in excess of 40 hours - of the so-called white nebula and determining startling radial velocities, evidence of an expanding universe. In the 1960s, scientists and artists teamed up on the Clark and created detailed lunar maps in support of the Apollo program.In recent decades, the Clark has played a central role in the education programs at Lowell, with general public audiences, students, and private groups all taking advantage of this unique resource.With this nearly 120 years of contant use, the Clark had been wearing down in recent years. The telescope was becoming more difficult to move, old electrical wiring in the dome was a fire hazard, and many of the telescope's parts needed to be repaired or replaced.In 2013, Lowell Observatory began a fundraising campaign, collecting $291,000 to cover the cost of dome and telescope renovation. Workers removed the entire telescope mount and tube assembly from the dome, examining every part from tube sections to individuals screws. They also stabilized the dome, adding a water vapor barrier and new outer wall while reinforcing the upper dome. The project lasted from January, 2014 through August, 2015. The facility reopened for daytime tours in September, 2015 and evening viewing the following month.

  7. Results of a 24-inch Hybrid Motor Performance Uncertainty Analysis

    NASA Technical Reports Server (NTRS)

    Sims, Joseph D.; Coleman, Hugh W.

    1998-01-01

    The subscale (11 and 24-inch) hybrid motors at the Marshall Space Flight Center (MSFC) have been used as versatile and cost effective testbeds for developing new technology. Comparisons between motor configuration, ignition systems, feed systems, fuel formulations, and nozzle materials have been carried out without detailed consideration as to haw "good" the motor performance data were. For the 250,000 lb/thrust motor developed by the Hybrid Propulsion Demonstration Program consortium, this shortcoming is particularly risky because motor performance will likely be used as put of a set of downselect criteria to choose between competing ignition and feed systems under development. This analysis directly addresses that shortcoming by applying uncertainty analysis techniques to the experimental determination of the characteristic velocity, theoretical characteristic velocity, and characteristic velocity efficiency for a 24-inch motor firing. With the adoption of fuel-lined headends, flow restriction, and aft mixing chambers, state of the an 24-inch hybrid motors have become very efficient However, impossibly high combustion efficiencies (some computed as high as 108%) have been measured in some tests with 11-inch motors. This analysis has given new insight into explaining how these efficiencies were measured to be so high, and into which experimental measurements contribute the most to the overall uncertainty.

  8. Water-tunnel investigation of concepts for alleviation of adverse inlet spillage interactions with external stores

    NASA Technical Reports Server (NTRS)

    Neuhart, Dan H.; Rhode, Matthew N.

    1990-01-01

    A test was conducted in the NASA Langley 16- by 24-Inch Water Tunnel to study alleviation of the adverse interactions of inlet spillage flow on the external stores of a fighter aircraft. A 1/48-scale model of a fighter aircraft was used to simulate the flow environment around the aircraft inlets and on the downstream underside of the fuselage. A controlled inlet mass flow was simulated by drawing water into the inlets. Various flow control devices were used on the underside of the aircraft model to manipulate the vortical inlet spillage flow.

  9. Evaluation of the Sun Microsystems 365-1352-01 16 x 10 Aspect Ratio, 24-Inch Diagonal Color Monitor

    DTIC Science & Technology

    2007-11-02

    System Tonal Transfer at center screen as a function of input counts. Sun Microsystems 365-1352-01, 24-Inch, 16:10 Aspect Ratio , Color CRT Monitor...for the Image Analyst and Cartographer applications. Evaluation of the Sun Microsystems 365-1352-01 16 x 10 Aspect Ratio , 24-Inch Diagonal Color Monitor...16 x 10 Aspect Ratio , 24-Inch Diagonal Color Monitor Contract Number Grant Number Program Element Number Author(s) Project Number Task Number Work

  10. The Little Thompson Observatory Receives the Retired Mt. Wilson 24-inch Telescope

    NASA Astrophysics Data System (ADS)

    Schweitzer, Andrea E.

    2006-12-01

    The Little Thompson Observatory is a community-built E/PO observatory and is a member of the Telescopes in Education (TIE) project. The observatory is located on the grounds of Berthoud High School in northern Colorado. Annually we have approximately 5,000 visitors, which is roughly equal to the population of the small town of Berthoud. During 2006 the LTO received the recently-retired 24-inch telescope from Mount Wilson. To provide a new home for this historic telescope, we are building a second dome and doubling the size of our observatory (all with volunteer labor), as well as refurbishing the telescope. This past year we held a Colorado Project ASTRO-GEO workshop, and used the funding from our NASA ROSS E/PO grant for additional teacher workshops -making use of the baseball-sized meteorite that landed in Berthoud in 2004. The observatory also supported magnet high-school astronomy courses available to students from the surrounding school districts. We thank the NASA ROSS E/PO program for providing funding.

  11. Optimizing Facility Configurations and Operating Conditions for Improved Performance in the NASA Ames 24 Inch Shock Tube

    NASA Technical Reports Server (NTRS)

    Bogdanoff, David W.; Cruden, Brett A.

    2016-01-01

    The Ames Electric Arc Shock Tube (EAST) is a shock tube wherein the driver gas can be heated by an electric arc discharge. The electrical energy is stored in a 1.2 MJ capacitor bank. Four inch and 24 inch diameter driven tubes are available. The facility is described and the need for testing in the 24 inch tube to better simulate low density NASA mission profiles is discussed. Three test entries, 53, 53B and 59, are discussed. Tests are done with air or Mars gas (95.7% CO2/2.7% N2/1.6% Ar) at pressures of 0.01 to 0.14 Torr. Velocities spanned 6.3-9.2 km/s, with a nominal center of 7 km/s. Many facility configurations are studied in an effort to improve data quality. Various driver and driven tube configurations and the use of a buffer section between the driver and the driven tube are studied. Diagnostics include test times, time histories of the shock light pulses and tilts of the shock wave off the plane normal to the tube axis. The report will detail the results of the various trials, give the best configuration/operating conditions found to date and provide recommendations for further improvements. Finally, diaphragm performance is discussed.

  12. Water Tunnel Flow Visualization Study Through Poststall of 12 Novel Planform Shapes

    NASA Technical Reports Server (NTRS)

    Gatlin, Gregory M.; Neuhart, Dan H.

    1996-01-01

    To determine the flow field characteristics of 12 planform geometries, a flow visualization investigation was conducted in the Langley 16- by 24-Inch Water Tunnel. Concepts studied included flat plate representations of diamond wings, twin bodies, double wings, cutout wing configurations, and serrated forebodies. The off-surface flow patterns were identified by injecting colored dyes from the model surface into the free-stream flow. These dyes generally were injected so that the localized vortical flow patterns were visualized. Photographs were obtained for angles of attack ranging from 10' to 50', and all investigations were conducted at a test section speed of 0.25 ft per sec. Results from the investigation indicate that the formation of strong vortices on highly swept forebodies can improve poststall lift characteristics; however, the asymmetric bursting of these vortices could produce substantial control problems. A wing cutout was found to significantly alter the position of the forebody vortex on the wing by shifting the vortex inboard. Serrated forebodies were found to effectively generate multiple vortices over the configuration. Vortices from 65' swept forebody serrations tended to roll together, while vortices from 40' swept serrations were more effective in generating additional lift caused by their more independent nature.

  13. A user's guide to the Langley 16-foot transonic tunnel complex. Revision 1

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The operational characteristics and equipment associated with the Langley 16-foot transonic tunnel complex which is located in buildings 1146 and 1234 at the Langley Research Center are described in detail. This complex consists of the 16-foot transonic wind tunnel, the static test facility, and the 16- by 24-inch water tunnel research facilities. The 16-foot transonic tunnel is a single-return atmospheric wind tunnel with a 15.5 foot diameter test section and a Mach number capability from 0.20 to 1.30. The emphasis for research conducted in this research complex is on the integration of the propulsion system into advanced aircraft concepts. In the past, the primary focus has been on the integration of nozzles and empennage into the afterbody of fighter aircraft. During the last several years this experimental research has been expanded to include developing the fundamental data base necessary to verify new theoretical concepts, inlet integration into fighter aircraft, nozzle integration for supersonic and hypersonic transports, nacelle/pylon/wing integration for subsonic transport configurations, and the study of vortical flows (in the 16- by 24-inch water tunnel). The purpose here is to provide a comprehensive description of the operational characteristics of the research facilities of the 16-foot transonic tunnel complex and their associated systems and equipments.

  14. Simultaneous three-dimensional velocity and mixing measurements by use of laser Doppler velocimetry and fluorescence probes in a water tunnel

    NASA Technical Reports Server (NTRS)

    Neuhart, Dan H.; Wing, David J.; Henderson, Uleses C., Jr.

    1994-01-01

    A water tunnel investigation was conducted to demonstrate the capabilities of a laser-based instrument that can measure velocity and fluorescence intensity simultaneously. Fluorescence intensity of an excited fluorescent dye is directly related to concentration level and is used to indicate the extent of mixing in flow. This instrument is a three-dimensional laser Doppler velocimeter (LDV) in combination with a fluorometer for measuring fluorescence intensity variations. This capability allows simultaneous flow measurements of the three orthogonal velocity components and mixing within the same region. Two different flows which were generated by two models were studied: a generic nonaxisymmetric nozzle propulsion simulation model with an auxiliary internal water source that generated a jet flow and an axisymmetric forebody model with a circular sector strake that generated a vortex flow. The off-body flow fields around these models were investigated in the Langley 16- by 24-Inch Water Tunnel. The experimental results were used to calculate 17 quantities that included mean and fluctuating velocities, Reynolds stresses, mean and fluctuating dye fluorescence intensities (proportional to concentration), and fluctuating velocity and dye concentration correlations. An uncertainty analysis was performed to establish confidence levels in the experimental results. In general, uncertainties in mean velocities varied between 1 and 7 percent of free-stream velocity; uncertainties in fluctuating velocities varied between 1 and 5 percent of reference values. The results show characteristics that are unique to each type of flow.

  15. Characteristics of Water Ingress in Norwegian Subsea Tunnels

    NASA Astrophysics Data System (ADS)

    Nilsen, Bjørn

    2014-05-01

    Water ingress represents one of the main challenges in subsea tunnelling, particularly when this occurs in sections with poor rock mass quality. This paper is discussing the main characteristics of water ingress in subsea hard rock tunnels based on the experience from almost 50 such tunnels that have been built in Norway. Following a brief description of the geological conditions and the basic design of the subsea tunnels, pre-construction investigations and investigations during excavation are discussed with particular emphasis on prediction of water ingress. Two cases with particularly difficult conditions; the Bjorøy tunnel and the Atlantic Ocean tunnel, are discussed in detail. In these cases, large water inflow with pressure of up to 2.4 MPa was encountered at major faults/weakness zones during excavation, and special procedures were required to cope with the problems. Based on the experience from the Norwegian projects, it is concluded that continuous follow-up by experienced engineering geologists, probe drilling with the drilling jumbo and pre-grouting where required are the most important factors for coping with water ingress and ensuring stability.

  16. Development of a 5-Component Balance for Water Tunnel Applications

    NASA Technical Reports Server (NTRS)

    Suarez, Carlos J.; Kramer, Brian R.; Smith, Brooke C.

    1999-01-01

    The principal objective of this research/development effort was to develop a multi-component strain gage balance to measure both static and dynamic forces and moments on models tested in flow visualization water tunnels. A balance was designed that allows measuring normal and side forces, and pitching, yawing and rolling moments (no axial force). The balance mounts internally in the model and is used in a manner typical of wind tunnel balances. The key differences between a water tunnel balance and a wind tunnel balance are the requirement for very high sensitivity since the loads are very low (typical normal force is 90 grams or 0.2 lbs), the need for water proofing the gage elements, and the small size required to fit into typical water tunnel models. The five-component balance was calibrated and demonstrated linearity in the responses of the primary components to applied loads, very low interactions between the sections and no hysteresis. Static experiments were conducted in the Eidetics water tunnel with delta wings and F/A-18 models. The data were compared to forces and moments from wind tunnel tests of the same or similar configurations. The comparison showed very good agreement, providing confidence that loads can be measured accurately in the water tunnel with a relatively simple multi-component internal balance. The success of the static experiments encouraged the use of the balance for dynamic experiments. Among the advantages of conducting dynamic tests in a water tunnel are less demanding motion and data acquisition rates than in a wind tunnel test (because of the low-speed flow) and the capability of performing flow visualization and force/moment (F/M) measurements simultaneously with relative simplicity. This capability of simultaneous flow visualization and for F/M measurements proved extremely useful to explain the results obtained during these dynamic tests. In general, the development of this balance should encourage the use of water tunnels for a

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    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.

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

    SciTech Connect

    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.

  20. Flow measurements in a water tunnel using a holocinematographic velocimeter

    NASA Technical Reports Server (NTRS)

    Weinstein, Leonard M.; Beeler, George B.

    1987-01-01

    Dual-view holographic movies were used to examine complex flows with full three-space and time resolution. This approach, which tracks the movement of small tracer particles in water, is termed holocinematographic velocimetry (HCV). A small prototype of a new water tunnel was used to demonstrate proof-of-concept for the HCV. After utilizing a conventional flow visualization apparatus with a laser light sheet to illuminate tracer particles to evaluate flow quality of the prototype tunnel, a simplified version of the HCV was employed to demonstrate the capabilities of the approach. Results indicate that a full-scale version of the water tunnel and a high performance version of the HCV should be able to check theoretical and numerical modeling of complex flows and examine the mechanisms operative in turbulent and vortex flow control concepts, providing an entirely unique instrument capable, for the first time, of simultaneous three-space and time measurements in turbulent flow.

  1. Flow measurements in a water tunnel using a holocinematographic velocimeter

    NASA Astrophysics Data System (ADS)

    Weinstein, Leonard M.; Beeler, George B.

    1987-06-01

    Dual-view holographic movies were used to examine complex flows with full three-space and time resolution. This approach, which tracks the movement of small tracer particles in water, is termed holocinematographic velocimetry (HCV). A small prototype of a new water tunnel was used to demonstrate proof-of-concept for the HCV. After utilizing a conventional flow visualization apparatus with a laser light sheet to illuminate tracer particles to evaluate flow quality of the prototype tunnel, a simplified version of the HCV was employed to demonstrate the capabilities of the approach. Results indicate that a full-scale version of the water tunnel and a high performance version of the HCV should be able to check theoretical and numerical modeling of complex flows and examine the mechanisms operative in turbulent and vortex flow control concepts, providing an entirely unique instrument capable, for the first time, of simultaneous three-space and time measurements in turbulent flow.

  2. 7. DRAIN TUNNEL PORTAL. THE WATER FLOWS IN A DITCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. DRAIN TUNNEL PORTAL. THE WATER FLOWS IN A DITCH BENEATH TIMBER LAGGING, WHICH SUPPORTS THE MINE CAR TRACKS. - Park Utah Mining Company: Keetley Mine Complex, 1 mile East of U.S. 40 at Keetley, Heber City, Wasatch County, UT

  3. Quantum tunneling and vibrational dynamics of ultra-confined water

    NASA Astrophysics Data System (ADS)

    Kolesnikov, Alexander I.; Anovitz, Lawrence M.; Ehlers, Georg; Mamontov, Eugene; Podlesnyak, Andrey; Prisk, Timothy R.; Seel, Andrew; Reiter, George F.

    2015-03-01

    Vibrational dynamics of ultra-confined water in single crystals beryl, the structure of which contains ~ 5 Å diameter channels along the c-axis was studied with inelastic (INS), quasi-elastic (QENS) and deep inelastic (DINS) neutron scattering. The results reveal significantly anisotropic dynamical behavior of confined water, and show that effective potential experienced by water perpendicular to the channels is significantly softer than along them. The observed 7 peaks in the INS spectra (at energies 0.25 to 15 meV), based on their temperature and momentum transfer dependences, are explained by transitions between the split ground states of water in beryl due to water quantum tunneling between the 6-fold equivalent positions across the channels. DINS study of beryl at T=4.3 K shows narrow, anisotropic water proton momentum distribution with corresponding kinetic energy, EK=95 meV, which is much less than was previously observed in bulk water (~150 meV). We believe that the exceptionally small EK in beryl is a result of water quantum tunneling ∖ delocalization in the nanometer size confinement and weak water-cage interaction. The neutron experiment at ORNL was sponsored by the Sci. User Facilities Div., BES, U.S. DOE. This research was sponsored by the Div. Chemical Sci, Geosciences, and Biosciences, BES, U.S. DOE. The STFC RAL is thanked for access to ISIS neutron facilities.

  4. Investigation of water droplet trajectories within the NASA icing research tunnel

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew; Ibrahim, Mounir

    1995-01-01

    Water droplet trajectories within the NASA Lewis Research Center's Icing Research Tunnel (IRT) were studied through computer analysis. Of interest was the influence of the wind tunnel contraction and wind tunnel model blockage on the water droplet trajectories. The computer analysis was carried out with a program package consisting of a three-dimensional potential panel code and a three-dimensional droplet trajectory code. The wind tunnel contraction was found to influence the droplet size distribution and liquid water content distribution across the test section from that at the inlet. The wind tunnel walls were found to have negligible influence upon the impingement of water droplets upon a wing model.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed

    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.

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

    DOE PAGES

    Kolesnikov, Alexander I.; Reiter, George F.; Choudhury, Narayani; ...

    2016-04-22

    When 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. Additionally, the water proton momentum distribution was measured with deep inelastic neutron scattering, which directly revealed coherent delocalization of the protons in the ground state.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    SciTech Connect

    Videla, Pablo E.; Rossky, Peter J.; Laria, D.

    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.

  11. Water-level, velocity, and dye measurements in the Chicago tunnels

    USGS Publications Warehouse

    Oberg, K.A.; Schmidt, A.R.; ,

    1993-01-01

    On April 13, 1992, a section of a 100-year-old underground freight tunnel in downtown Chicago, Illinois was breached where the tunnel crosses under the Chicago River, about 15 meters below land surface. The breach allowed water from the Chicago River to flow into the freight tunnels and into buildings connected to the tunnels. As a result, utility services to more than 100 buildings in downtown Chicago were lost, several hundred thousand workers were sent home, and the entire subway system and a major expressway in the Loop were shut down. The breach in the tunnel was sealed and the tunnel dewatered by the U.S. Army Corps of Engineers (Corps) and its contractors. The U.S. Geological Survey (USGS) assisted the Corps in their efforts to plug and dewater the freight tunnels and connected buildings. This assistance included the installation and operation of telemetered gages for monitoring water levels in the tunnel system and velocity measurements made in the vicinity of the tunnel breach. A fluorescent dye tracer was used to check for leaks in the plugs, which isolated the damaged portion of the Chicago freight tunnel from the remainder of the tunnel system.

  12. The NASA Lewis Research Center Water Tunnel Facility

    NASA Technical Reports Server (NTRS)

    Wasserbauer, Charles A.

    1997-01-01

    A water tunnel facility specifically designed to investigate internal fluid duct flows has been built at the NASA Research Center. It is built in a modular fashion so that a variety of internal flow test hardware can be installed in the facility with minimal facility reconfiguration. The facility and test hardware interfaces are discussed along with design constraints for future test hardware. The inlet chamber flow conditioning approach is also detailed. Instrumentation and data acquisition capabilities are discussed. The incoming flow quality has been documented for about one quarter of the current facility operating range. At that range, there is some scatter in the data in the turbulent boundary layer which approaches 10 percent of the duct radius leading to a uniform core.

  13. Static and dynamic force/moment measurements in the Eidetics water tunnel

    NASA Technical Reports Server (NTRS)

    Suarez, Carlos J.; Malcolm, Gerald N.

    1994-01-01

    Water tunnels have been utilized in one form or another to explore fluid mechanics and aerodynamics phenomena since the days of Leonardo da Vinci. Water tunnel testing is attractive because of the relatively low cost and quick turn-around time to perform flow visualization experiments and evaluate the results. The principal limitation of a water tunnel is that the low flow speed, which provides for detailed visualization, also results in very small hydrodynamic (aerodynamic) forces on the model, which, in the past, have proven to be difficult to measure accurately. However, the advent of semi-conductor strain gage technology and devices associated with data acquisition such as low-noise amplifiers, electronic filters, and digital recording have made accurate measurements of very low strain levels feasible. The principal objective of this research effort was to develop a multi-component strain gage balance to measure forces and moments on models tested in flow visualization water tunnels. A balance was designed that allows measuring normal and side forces, and pitching, yawing and rolling moments (no axial force). The balance mounts internally in the model and is used in a manner typical of wind tunnel balances. The key differences between a water tunnel balance and a wind tunnel balance are the requirement for very high sensitivity since the loads are very low (typical normal force is 0.2 lbs), the need for water proofing the gage elements, and the small size required to fit into typical water tunnel models.

  14. Finite-rate water condensation in combustion-heated wind tunnels

    NASA Technical Reports Server (NTRS)

    Erickson, Wayne D.; Mall, Gerald H.; Prabhu, Ramadas K.

    1988-01-01

    A quasi-one-dimensional method for computing finite rate nucleation and droplet growth of water in a supersonic expansion of combustion products is presented. Sample computations are included for the Langley 8 foot High Temperature Tunnel, but the method can also be applied to other combustion heated wind tunnels. The sample results indicate that the free stream static pressure can be in the range of 25 to 60 percent greater than that computed for isentropic nozzle flow without water condensation. The method provides a tool for examining the effects of water condensation on static state properties and velocity of the supersonic stream in combustion heated wind tunnels.

  15. Water-tunnel study of transition flow around circular cylinders

    NASA Technical Reports Server (NTRS)

    Almosnino, D.; Mcalister, K. W.

    1984-01-01

    The recently reported phenomenon of asymmetric flow separation from a circular cylinder in the critical Reynolds number regime has been confirmed in a water-tunnel experiment. For the first time, an attempt was made to visualize the wake of the cylinder during the transition from subcritical to critical flow and to correlate the visualizations with lift and drag measurements. The occurrence of a dominant asymmetric-flow state was quite repeatable, both when increasing and decreasing the Reynolds number, resulting in a mean lift coefficient of C sub L approx 1.2 and a shift in the angle of the wake by about 12 deg. A distinctive step change in the drag and shedding frequency was also found to occur. A hysteresis was confirmed to exist in this region as the Reynolds number was cycled over the transition range. Both boundaries of the asymmetry appear to be supercritical bifurcations in the flow. The asymmetry was normally steady in the mean; however, there were instances when the direction of the asymmetry reversed and remained so for the duration of the Reynolds number sweep through this transition region. A second asymmetry was observed at a higher Reynolds number; however, the mean lift coefficient was much lower, and the direction of the asymmetry was not observed to reverse. Introducing a small local disturbance into the boundary layer was found to prevent the critical asymmetry from developing along the entire span of the cylinder.

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

    NASA Astrophysics Data System (ADS)

    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

  17. Uncertainty Analysis for Assessing Leakage Through Water Tunnels: A Case from Nepal Himalaya

    NASA Astrophysics Data System (ADS)

    Panthi, Krishna Kanta; Nilsen, Bjørn

    2010-09-01

    Water leakage problems in unlined or shotcrete lined water tunnels are not new issues. In many occasions severe water leakage problems have been faced that not only have reduced the stability of the rock mass, but also have caused valuable water to be lost from it, causing safety risk as well as huge economic loss to the projects. Hence, making tunnels water tight plays an important role in improving stability and safety of underground excavations. The real challenge is however accurate prediction and quantification of possible water leakage, so that cost consequences can be incorporated during planning of a water conveying tunnel project. The main purposes of this paper are to analyze extensive data on leakage test carried out through exploratory drillhole used to define the need for pre-injection grouting of Khimti headrace tunnel and to carry out probabilistic approach of uncertainty analysis based on relationship established between leakage, hydrostatic head and selected Q-value parameters. The authors believe that the new approach regarding uncertainty analysis of leakage presented in this paper will improve the understanding of leakage characteristics of the rock mass, and hope this will lead to a better understanding concerning quantification of possible water leakage from unlined and shotcrete lined water tunnels.

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

    USGS Publications Warehouse

    Walton-Day, K.; Poeter, E.

    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 (??18O and ??2H) 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

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

    USGS Publications Warehouse

    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

  20. Modelling of deformation of underground tunnel lining, interacting with water-saturated soil

    NASA Astrophysics Data System (ADS)

    Berezhnoi, D. V.; Balafendieva, I. S.; Sachenkov, A. A.; Sekaeva, L. R.

    2016-11-01

    Built finite element method of calculating the deformation of underground tunnel lining, interacting with dry and water-saturated soils. To simulate the interaction between the lining and soils environments, including physical and non-linear, a special "contact" finite element, which allows to consider all cases of interaction between the contacting surfaces. It solved a number of problems of deformation with the ground subway tunnel lining rings.

  1. Experimental modeling of pressurized subglacial water flow: Implications for tunnel valley formation

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    Tunnel valleys are elongated hollows commonly found in formerly glaciated areas and interpreted as resulting from subglacial meltwater erosion beneath ice sheets. Over the past two decades, the number of studies of terrestrial tunnel valleys has continuously increased, and their existence has been hypothesized also on Mars, but their formation mechanisms remain poorly understood. We introduce here an innovative experimental approach to examine erosion by circulation of pressurized meltwater within the substratum and at the ice/substratum interface. We used a permeable substratum (sand) partially covered by a viscous, impermeable, and transparent cap (silicon putty), below which we applied a central injection of pure water. Low water pressures led to groundwater circulation in the substratum only, while water pressures exceeding a threshold that is larger than the sum of the glaciostatic and lithostatic pressures led to additional water circulation and formation of drainage landforms at the cap/substratum interface. The formation of these drainage landforms was monitored through time, and their shapes were analyzed from digital elevation models obtained by stereo-photogrammetry. The experimental landforms include valleys that are similar to natural tunnel valleys in their spatial organization and in a number of diagnostic morphological criteria, such as undulating longitudinal profiles and "tunnel" shapes. These results are consistent with the hypothesis that overpressurized subglacial water circulation controls the formation of tunnel valleys.

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

    NASA Astrophysics Data System (ADS)

    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

  3. Appraisal of ground water in the vicinity of the Leadville drainage tunnel, Lake County, Colorado

    USGS Publications Warehouse

    Turk, John T.; Taylor, O. James

    1979-01-01

    Ground water in the Leadville mining district occurs in granite, quartzite, limestone, sandstone, porphyry dikes, and unconsolidated material. These rocks form a single aquifer system because the formations are hydraulically connected through contact, mine workings, faulting, and fracturing. The aquifer is recharged by precipitation and water moves toward California Gulch and probably toward Evans Gulch, in the drainage basin of the Arkansas River. The Leadville drainage tunnel was constructed from 1943 to 1945 and later extended during 1950 to 1952, in order to drain the mine workings. Discharge from the tunnel lowered water levels 30 to 96 feet in mine shafts from 1944 to 1951. Installation of an impervious plug in the tunnel has been proposed in order to reduce the discharge of water containing objectionable concentrations of trace metals into the East Fork Arkansas River. The proposed plug would reduce the discharge from the tunnel, cause water levels east of the town of Leadville to rise, flood some mine workings, and increase ground-water discharge to California Gulch. However, the proposed plug is not expected to cause water levels in Leadville to rise substantially, but more current and detailed data are needed to verify this. Discharge from the Leadville drainage tunnel is probably a mixture of water in equilibrium with carbonate aquifer materials from the mineralized zone, water acidified by the localized oxidation of pyrite from the mineralized zone, and water nearly saturated with calcite from the glacial mantle. Based on limited data, water from the carbonate mineral deposits has a pH of about 7.0 and concentrations of manganese of about 1,800 micrograms per liter and zinc concentrations of about 13,000 micrograms per liter. (USGS)

  4. Air/water two-phase flow test tunnel for airfoil studies

    NASA Astrophysics Data System (ADS)

    Ohashi, H.; Matsumoto, Y.; Ichikawa, Y.; Tsukiyama, T.

    1990-02-01

    A test tunnel for the study of airfoil performances under air/water two-phase flow condition has been designed and constructed. This facility will serve for a better understanding of the flow phenomena and characteristics of hydraulic machinery under gas/ liquid two-phase flow operating conditions. At the test section of the tunnel, a two-dimensional isolated airfoil or a cascade of airfoils is installed in a two-phase inlet flow with a uniform velocity (up to 10 m/s) and void fraction (up to 12%) distribution. The details of the tunnel structure and the measuring systems are described and the basic characteristics of the constructed tunnel are also given. As an example of the test results, void fraction distribution around a test airfoil is shown.

  5. Air/water two-phase flow test tunnel for airfoil studies

    NASA Astrophysics Data System (ADS)

    Ohashi, H.; Matsumoto, Y.; Ichikawa, Y.; Tsukiyama, T.

    1994-01-01

    A test tunnel for the study of airfoil performances under air/water two-phase flow condition has been designed and constructed. This facility will serve for a better understanding of the flow phenomena and characteristics of hydraulic machinery under gas/ liquid two-phase flow operating conditions. At the test section of the tunnel, a two-dimensional isolated airfoil or a cascade of airfoils is installed in a two-phase inlet flow with a uniform velocity (up to 10 m/s) and void fraction (up to 12%) distribution. The details of the tunnel structure and the measuring systems are described and the basic characteristics of the constructed tunnel are also given. As an example of the test results, void fraction distribution around a test airfoil is shown.

  6. Development of a multicomponent force and moment balance for water tunnel applications, volume 2

    NASA Technical Reports Server (NTRS)

    Suarez, Carlos J.; Malcolm, Gerald N.; Kramer, Brian R.; Smith, Brooke C.; Ayers, Bert F.

    1994-01-01

    The principal objective of this research effort was to develop a multicomponent strain gauge balance to measure forces and moments on models tested in flow visualization water tunnels. Static experiments (which are discussed in Volume 1 of this report) were conducted, and the results showed good agreement with wind tunnel data on similar configurations. Dynamic experiments, which are the main topic of this Volume, were also performed using the balance. Delta wing models and two F/A-18 models were utilized in a variety of dynamic tests. This investigation showed that, as expected, the values of the inertial tares are very small due to the low rotating rates required in a low-speed water tunnel and can, therefore, be ignored. Oscillations in pitch, yaw and roll showed hysteresis loops that compared favorably to data from dynamic wind tunnel experiments. Pitch-up and hold maneuvers revealed the long persistence, or time-lags, of some of the force components in response to the motion. Rotary-balance experiments were also successfully performed. The good results obtained in these dynamic experiments bring a whole new dimension to water tunnel testing and emphasize the importance of having the capability to perform simultaneous flow visualization and force/moment measurements during dynamic situations.

  7. Development of a multicomponent force and moment balance for water tunnel applications, volume 2

    NASA Astrophysics Data System (ADS)

    Suarez, Carlos J.; Malcolm, Gerald N.; Kramer, Brian R.; Smith, Brooke C.; Ayers, Bert F.

    1994-12-01

    The principal objective of this research effort was to develop a multicomponent strain gauge balance to measure forces and moments on models tested in flow visualization water tunnels. Static experiments (which are discussed in Volume 1 of this report) were conducted, and the results showed good agreement with wind tunnel data on similar configurations. Dynamic experiments, which are the main topic of this Volume, were also performed using the balance. Delta wing models and two F/A-18 models were utilized in a variety of dynamic tests. This investigation showed that, as expected, the values of the inertial tares are very small due to the low rotating rates required in a low-speed water tunnel and can, therefore, be ignored. Oscillations in pitch, yaw and roll showed hysteresis loops that compared favorably to data from dynamic wind tunnel experiments. Pitch-up and hold maneuvers revealed the long persistence, or time-lags, of some of the force components in response to the motion. Rotary-balance experiments were also successfully performed. The good results obtained in these dynamic experiments bring a whole new dimension to water tunnel testing and emphasize the importance of having the capability to perform simultaneous flow visualization and force/moment measurements during dynamic situations.

  8. Scanning tunneling microscopy study and nanomanipulation of graphene-coated water on mica.

    PubMed

    He, Kevin T; Wood, Joshua D; Doidge, Gregory P; Pop, Eric; Lyding, Joseph W

    2012-06-13

    We study interfacial water trapped between a sheet of graphene and a muscovite (mica) surface using Raman spectroscopy and ultrahigh vacuum scanning tunneling microscopy (UHV-STM) at room temperature. We are able to image the graphene-water interface with atomic resolution, revealing a layered network of water trapped underneath the graphene. We identify water layer numbers with a carbon nanotube height reference. Under normal scanning conditions, the water structures remain stable. However, at greater electron energies, we are able to locally manipulate the water using the STM tip.

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

  10. MTR, TRA603. SUBBASEMENT FLOOR PLAN. INLET/OUTLET TUNNELS FOR COOLANT WATER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    MTR, TRA-603. SUB-BASEMENT FLOOR PLAN. INLET/OUTLET TUNNELS FOR COOLANT WATER (NORTH SIDE) AND AIR (SOUTH SIDE). RABBIT CANAL AND BULKHEADS. SUMPS AND DRAINS. BLAW-KNOX 3150-3-7, 3/1950. INL INDEX NO. 531-0603-00-098-100006, REV. 4. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  11. Thin insulating tunneling contacts for efficient and water-resistant perovskite solar cells

    SciTech Connect

    Wang, Qi; Dong, Qingfeng; Li, Tao; Gruverman, Alexei; Huang, Jinsong

    2016-05-17

    Here, we demonstrated that inserting a tunneling layer between perovskite and electron transport layer could significantly increase device performance by suppressing carrier recombination at the cathode contact. The tunneling layer can also serve as an encapsulation layer to prevent perovskite film from damage caused by water or moisture. This method is simple because it does not need lattice matching between the buffer layer and perovskite. The low temperature solution process makes it compatible with many types of perovskite materials, and may be applied for anode contact as well. The freedom to choose any insulating layer for contact enables more device designs and manufacturing.

  12. Thin insulating tunneling contacts for efficient and water-resistant perovskite solar cells

    DOE PAGES

    Wang, Qi; Dong, Qingfeng; Li, Tao; ...

    2016-05-17

    Here, we demonstrated that inserting a tunneling layer between perovskite and electron transport layer could significantly increase device performance by suppressing carrier recombination at the cathode contact. The tunneling layer can also serve as an encapsulation layer to prevent perovskite film from damage caused by water or moisture. This method is simple because it does not need lattice matching between the buffer layer and perovskite. The low temperature solution process makes it compatible with many types of perovskite materials, and may be applied for anode contact as well. The freedom to choose any insulating layer for contact enables more devicemore » designs and manufacturing.« less

  13. Tunneling splittings in the water dimer: Further development of the theory

    NASA Astrophysics Data System (ADS)

    Coudert, L. H.; Hougen, J. T.

    1988-07-01

    Energy level expressions are derived for the hydrogen-bonded water dimer complex and some of its deuterated species, using a previously reported internal-axis-method-like formalism developed for high barrier tunneling problems involving several large-amplitude motions. First, the feasibility of various tunneling motions is considered, using a potential surface given by D. F. Coker and R. O. Watts ( J. Phys. Chem.91, 2513-2518 (1987)), and three main tunneling paths for (H 2O) 2 are chosen. We assume that the most feasible path corresponds to a 180° rotation of the acceptor monomer; that the next most feasible path corresponds to a geared-type rotation of the two monomers, leading to an exchange of donor and acceptor monomer roles; and that the third most feasible path corresponds to an exchange of donor hydrogen atoms in the hydrogen bond, accompanied by an umbrella motion of the acceptor monomer. As the second step, the J and K dependence of the purely vibrational tunneling splittings, which arises in the IAM-like formalism because angular momentum is generated during the tunneling motions, is taken into account by computing sets of angles χ, θ, φ for Wigner D( J) ( χ, θ, φ) K, K' expressions appearing as factors in the vibrational tunneling matrix elements. Symmetry relations determined for the angles χ, θ, φ greatly simplify the calculations. Finally, the Hamiltonian matrix is set up and diagonalized to obtain the desired energy level expressions (used without proof in an earlier paper treating observed microwave transitions of (H 2O) 2). The J and K dependence of the tunneling splittings arising from the presence of rotational terms in the effective Hamiltonian operator is also discussed, but only for the most symmetric species (H 2O) 2 and (D 2O) 2.

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

    NASA Astrophysics Data System (ADS)

    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 (<1%). Low-density materials also tend to equilibrate with air over much longer timescales (> 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

  15. Development of a multicomponent force and moment balance for water tunnel applications, volume 1

    NASA Technical Reports Server (NTRS)

    Suarez, Carlos J.; Malcolm, Gerald N.; Kramer, Brian R.; Smith, Brooke C.; Ayers, Bert F.

    1994-01-01

    The principal objective of this research effort was to develop a multicomponent strain gauge balance to measure forces and moments on models tested in flow visualization water tunnels. An internal balance was designed that allows measuring normal and side forces, and pitching, yawing and rolling moments (no axial force). The five-components to applied loads, low interactions between the sections and no hysteresis. Static experiments (which are discussed in this Volume) were conducted in the Eidetics water tunnel with delta wings and a model of the F/A-18. Experiments with the F/A-18 model included a thorough baseline study and investigations of the effect of control surface deflections and of several Forebody Vortex Control (FVC) techniques. Results were compared to wind tunnel data and, in general, the agreement is very satisfactory. The results of the static tests provide confidence that loads can be measured accurately in the water tunnel with a relatively simple multicomponent internal balance. Dynamic experiments were also performed using the balance, and the results are discussed in detail in Volume 2 of this report.

  16. Development of a multicomponent force and moment balance for water tunnel applications, volume 1

    NASA Astrophysics Data System (ADS)

    Suarez, Carlos J.; Malcolm, Gerald N.; Kramer, Brian R.; Smith, Brooke C.; Ayers, Bert F.

    1994-12-01

    The principal objective of this research effort was to develop a multicomponent strain gauge balance to measure forces and moments on models tested in flow visualization water tunnels. An internal balance was designed that allows measuring normal and side forces, and pitching, yawing and rolling moments (no axial force). The five-components to applied loads, low interactions between the sections and no hysteresis. Static experiments (which are discussed in this Volume) were conducted in the Eidetics water tunnel with delta wings and a model of the F/A-18. Experiments with the F/A-18 model included a thorough baseline study and investigations of the effect of control surface deflections and of several Forebody Vortex Control (FVC) techniques. Results were compared to wind tunnel data and, in general, the agreement is very satisfactory. The results of the static tests provide confidence that loads can be measured accurately in the water tunnel with a relatively simple multicomponent internal balance. Dynamic experiments were also performed using the balance, and the results are discussed in detail in Volume 2 of this report.

  17. Visualizing the tunnel in tryptophan synthase with crystallography: Insights into a selective filter for accommodating indole and rejecting water.

    PubMed

    Hilario, Eduardo; Caulkins, Bethany G; Huang, Yu-Ming M; You, Wanli; Chang, Chia-En A; Mueller, Leonard J; Dunn, Michael F; Fan, Li

    2016-03-01

    Four new X-ray structures of tryptophan synthase (TS) crystallized with varying numbers of the amphipathic N-(4'-trifluoromethoxybenzoyl)-2-aminoethyl phosphate (F6) molecule are presented. These structures show one of the F6 ligands threaded into the tunnel from the β-site and reveal a distinct hydrophobic region. Over this expanse, the interactions between F6 and the tunnel are primarily nonpolar, while the F6 phosphoryl group fits into a polar pocket of the β-subunit active site. Further examination of TS structures reveals that one portion of the tunnel (T1) binds clusters of water molecules, whereas waters are not observed in the nonpolar F6 binding region of the tunnel (T2). MD simulation of another TS structure with an unobstructed tunnel also indicates the T2 region of the tunnel excludes water, consistent with a dewetted state that presents a significant barrier to the transfer of water into the closed β-site. We conclude that hydrophobic molecules can freely diffuse between the α- and β-sites via the tunnel, while water does not. We propose that exclusion of water serves to inhibit reaction of water with the α-aminoacrylate intermediate to form ammonium ion and pyruvate, a deleterious side reaction in the αβ-catalytic cycle. Finally, while most TS structures show βPhe280 partially blocking the tunnel between the α- and β-sites, new structures show an open tunnel, suggesting the flexibility of the βPhe280 side chain. Flexible docking studies and MD simulations confirm that the dynamic behavior of βPhe280 allows unhindered transfer of indole through the tunnel, therefore excluding a gating role for this residue.

  18. Tunnels and dikes of the Koolau Range, Oahu, Hawaii, and their effect on storage depletion and movement of ground water

    USGS Publications Warehouse

    Hirashima, George Tokusuke

    1971-01-01

    Ground water impounded by dikes in the Koolau Range is a major source of water for the island of Oahu, Hawaii, and many tunnels have been bored into the range to develop it. All water-development tunnels, except Waihee tunnel, have depleted storage in the rocks they penetrate and are now discharging at rates that are but fractions of the rates possible at full storage. Rocks above the floor of the water-development part of Waihee tunnel have never been completely dewatered, and storage can be manipulated by regulating outflow. Thus, storage for this tunnel can be increased during periods of low demand and discharged at high rates during periods of high demand. A measure of the rate of drainage or depletion of storage is the recession constant b in the recession-curve equation Qt=Q0e-b t. The higher the value of b, the faster water can be drawn from storage or returned to storage through artificial recharge. Mathematical analysis of the flow-recession curve of Waihee tunnel shows that (1) its recession constant is 0.00401, (2) net storage (exclusive of recharge) is 2,200 million gallons (6,800 acre-feet), and (8) initial discharge from full storage would be about 19 million gallons per day. Analysis of flow-recession curves for Waiahole ditch tunnel (main bore) and Haiku tunnel shows that these tunnels have drainage characteristics that are similar to those of Waihee tunnel. The composite recession constant computed for the four tunnels north of Waiahole is about one-third as large as that computed for the Waiahole ditch tunnel (main bore) and the tunnels to the south. The difference is due to an abrupt change in spacing of dikes north of Waiahole. At and south of Waiahole Stream, dikes are spaced tens or hundreds of feet apart; north of Waiahole, they are spaced inches or a few feet apart. Storage could be restored by bulkheading at the controlling dike or dikes after an analysis is made of the flow-recession curve for each tunnel. Such analyses will show which

  19. Chemical and ecological effects of contaminated tunnel wash water runoff to a small Norwegian stream.

    PubMed

    Meland, Sondre; Borgstrøm, Reidar; Heier, Lene Sørlie; Rosseland, Bjørn Olav; Lindholm, Oddvar; Salbu, Brit

    2010-09-01

    Cleaning and washing of road tunnels are routinely performed and large volumes of contaminated wash water are often discharged into nearby recipients. In the present study, traffic related contaminants were quantified in tunnel wash water (the Nordby tunnel, Norway) discharged from a sedimentation pond to a nearby small stream, Arungselva. In situ size and charge fractionation techniques were applied to quantify traffic related metal species, while PAHs were quantified in total samples. All metals and several PAHs appeared at elevated concentrations in the discharged wash water compared with concentrations measured in Arungselva upstream the pond outlet, and to concentrations measured in the pond outlet before the tunnel wash event. In addition, several contaminants (e.g. Cu, Pb, Zn, fluoranthene, pyrene) exceeded their corresponding EQS. PAH and metals like Al, Cd, Cr, Cu, Fe and Pb were associated with particles and colloids, while As, Ca, K, Mg, Mo, Ni, Sb and Zn were more associated with low molecular mass species (<10kDa). Calculated enrichment factors revealed that many of the metals were derived from anthropogenic sources, originating most likely from wear of tires (Zn), brakes (Cu and Sb), and from road salt (Na and Cl). The enrichment factors for Al, Ba, Ca, Cr, Fe, K, Mg and Ni were low, suggesting a crustal origin, e.g. asphalt wear. Based on calculated PAH ratios, PAH seemed to originate from a mixture of sources such as wear from tires, asphalt and combustion. Finally, historical fish length measurement data indicates that the fish population in the receiving stream Arungselva may have been adversely influenced by the chemical perturbations in runoffs originating from the nearby roads and tunnels during the years, as the growth in summer old sea trout (Salmo trutta L.) in downstream sections of the stream is significantly reduced compared to the upstream sections.

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

    PubMed

    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. Liquid water content and droplet size calibration of the NASA Lewis Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Ide, Robert F.

    1989-01-01

    The icing research tunnel at the NASA Lewis Research Center underwent a major rehabilitation in 1986 to 1987, necessitating recalibration of the icing cloud. The methods used in the recalibration, including the procedure used to establish a uniform icing cloud and the use of a standard icing blade technique for measurement of liquid water content are described. PMS Forward Scattering Spectrometer and Optical Array probes were used for measurement of droplet size. Examples of droplet size distributions are shown for several median volumetric diameters. Finally, the liquid water content/droplet size operating envelopes of the icing tunnel are shown for a range of airspeeds and are compared to the FAA icing certification criteria.

  2. Nonlinear transonic Wall-Interference Assessment/Correction (WIAC) procedures and application to cast-10 airfoil results from the NASA 0.3-m TCT 8- by 24-inch Slotted Wall Test Section (SWTS)

    NASA Technical Reports Server (NTRS)

    Gumbert, Clyde R.; Green, Lawrence L.; Newman, Perry A.

    1989-01-01

    From the time that wind tunnel wall interference was recognized to be significant, researchers have been developing methods to alleviate or account for it. Despite the best effort so far, it appears that no method is available which completely eliminates the effects due to the wind tunnel walls. This report discusses procedures developed for slotted wall and adaptive wall test sections of the Langley 0.3-m Transonic Cryogenic Tunnel (TCT) to assess and correct for the residual interference by methods consistent with the transonic nature of the tests.

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

    NASA Technical Reports Server (NTRS)

    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.

  4. Hybrid Wing Body Model Identification Using Forced-Oscillation Water Tunnel Data

    NASA Technical Reports Server (NTRS)

    Murphy, Patrick C.; Vicroy, Dan D.; Kramer, Brian; Kerho, Michael

    2014-01-01

    Static and dynamic testing of the NASA 0.7 percent scale Hybrid Wing Body (HWB) configuration was conducted in the Rolling Hills Research Corporation water tunnel to investigate aerodynamic behavior over a large range of angle-of-attack and to develop models that can predict aircraft response in nonlinear unsteady flight regimes. This paper reports primarily on the longitudinal axis results. Flow visualization tests were also performed. These tests provide additional static data and new dynamic data that complement tests conducted at NASA Langley 14- by 22-Foot Subsonic Tunnel. HWB was developed to support the NASA Environmentally Responsible Aviation Project goals of lower noise, emissions, and fuel burn. This study also supports the NASA Aviation Safety Program efforts to model and control advanced transport configurations in loss-of-control conditions.

  5. Perspective: Structure and dynamics of water at surfaces probed by scanning tunneling microscopy and spectroscopy.

    PubMed

    Guo, Jing; Bian, Ke; Lin, Zeren; Jiang, Ying

    2016-10-28

    The detailed and precise understanding of water-solid interaction largely relies on the development of atomic-scale experimental techniques, among which scanning tunneling microscopy (STM) has proven to be a noteworthy example. In this perspective, we review the recent advances of STM techniques in imaging, spectroscopy, and manipulation of water molecules. We discuss how those newly developed techniques are applied to probe the structure and dynamics of water at solid surfaces with single-molecule and even submolecular resolution, paying particular attention to the ability of accessing the degree of freedom of hydrogen. In the end, we present an outlook on the directions of future STM studies of water-solid interfaces as well as the challenges faced by this field. Some new scanning probe techniques beyond STM are also envisaged.

  6. Perspective: Structure and dynamics of water at surfaces probed by scanning tunneling microscopy and spectroscopy

    NASA Astrophysics Data System (ADS)

    Guo, Jing; Bian, Ke; Lin, Zeren; Jiang, Ying

    2016-10-01

    The detailed and precise understanding of water-solid interaction largely relies on the development of atomic-scale experimental techniques, among which scanning tunneling microscopy (STM) has proven to be a noteworthy example. In this perspective, we review the recent advances of STM techniques in imaging, spectroscopy, and manipulation of water molecules. We discuss how those newly developed techniques are applied to probe the structure and dynamics of water at solid surfaces with single-molecule and even submolecular resolution, paying particular attention to the ability of accessing the degree of freedom of hydrogen. In the end, we present an outlook on the directions of future STM studies of water-solid interfaces as well as the challenges faced by this field. Some new scanning probe techniques beyond STM are also envisaged.

  7. Classification of hydrogen bond flips in small water polyhedra applied to concerted proton tunneling.

    PubMed

    Kirov, M V

    2016-10-05

    Recently a new mechanism of proton tunneling in a prism-like water hexamer was revealed [Richardson et al., Science, 2016, 351, 1310]. The tunneling motion involves the concerted breaking of two hydrogen bonds and rotations of two nearest water molecules. Eventually, this structural transformation means flipping one of the hydrogen bonds without the creation of defects in the hydrogen bond network. On the surface of polyhedral water clusters, there are five essentially different types of hydrogen bonds, and only two of them can be changed in this manner. In this article, the topological classification of such transformations for five small water polyhedra: triangular, pentagonal, and hexagonal prisms as well as cube and polyhedron 4(4)5(4), consisting of four square and four pentagonal faces, is presented. Our classification includes the enumeration of all possible one-bond-flips with consideration of the types of hydrogen bonds on the polyhedral surface. Attention is paid to the most stable proton configurations which can be studied in experiments. It was established that a number of one-bond-flip transitions between the low energy configurations are possible in clusters in the shape of triangular and pentagonal prisms.

  8. Variational transition state theory calculations of tunneling effects on concerted hydrogen motion in water clusters and formaldehyde/water clusters

    SciTech Connect

    Garrett, B.C. ); Melius, C.F. )

    1990-08-01

    The direct participation of water molecules in aqueous phase reaction processes has been postulated to occur via both single-step mechanisms as well as concerted hydrogen atom or proton shifts. In the present work, simple prototypes of concerted hydrogen atom transfer processes are examined for small hydrogen-bonded water clusters -- cyclic trimers and tetramers -- and hydrogen-bonded clusters of formaldehyde with one and two water molecules. Rate constants for the rearrangement processes are computed using variational transition state theory, accounting for quantum mechanical tunneling effects by semiclassical ground-state adiabatic transmission coefficients. The variational transition state theory calculations directly utilize selected information about the potential energy surface along the minimum energy path as parameters of the reaction path Hamiltonian. The potential energy information is obtained from ab ignite electronic structure calculations with an empirical bond additivity correction (the BAC-MP4 method). Tunneling is found to be very important for these concerted rearrangement processes -- the semiclassical ground-state adiabatic transmission coefficients are estimated to be as high as four order of magnitude at room temperature. Effects of the size of the cluster (number of water molecules in the cyclic complex) are also dramatic -- addition of a water molecule is seen to change the calculated rates by orders of magnitude. 36 refs., 10 figs.

  9. An Experimental Investigation Into the Feasibility of Measuring Static and Dynamic Aerodynamic Derivatives in the DSTO Water Tunnel

    DTIC Science & Technology

    2013-08-01

    in the DSTO water tunnel. The current experimental program to determine derivatives, including the method used to reduce data, is based on the...chord (MAC) of a model, (m). d Model fuselage base diameter, (m). f Equivalent constant circular frequency of rotation for oscillatory pitching...tunnel using a Standard Dynamics Model (SDM). The experimental program, including data processing, is based on the recommendations given by Newman

  10. Water tunnel flow visualisation of vortex breakdown over the F/A-18

    NASA Astrophysics Data System (ADS)

    Thompson, D. H.

    1990-12-01

    Vortex flow patterns over models of the F/A-18 aircraft were visualized using dye and hydrogen bubble techniques in a water tunnel. The axial position of vortex breakdown in the leading-edge extension (LEX) vortices was measured, and was found to be insensitive to Reynolds number, to flap setting, and to small variations in model cross-section shape. Engine inlet flow did alter the vortex breakdown position, at flow rates that might be encountered under flight conditions. The fitting of fences on the LEX upper surface did not affect the axial position of vortex breakdown, but did alter the vortex structure. These alterations were examined in some detail.

  11. Detection of dilute organic acids in water by inelastic tunneling spectroscopy

    NASA Technical Reports Server (NTRS)

    Skarlatos, Y.; Barker, R. C.; Haller, G. L.; Yelon, A.

    1974-01-01

    Study of inelastic electron tunneling spectroscopy (IETS) spectra obtained from junctions exposed to dilute solutions of organic molecules in both liquid and vapor phases. The results indicate that it is possible in principle to detect the presence and to measure the concentration of at least some organic molecules in dilute aqueous solution by means of the IETS technique. Some fine points pertaining to the application of this technique are discussed, and it is pointed out that through appropriate refinements IETS may become a valuable tool for analytical water chemistry.

  12. Propellers of Minimum Induced Loss, and Water Tunnel Tests of Such a Propeller

    NASA Technical Reports Server (NTRS)

    Larrabee, E. E.

    1975-01-01

    The fundamental vortex theory for a single rotation propeller with a finite number of blades is reviewed. The theory leads to the specification of a radial distribution of bound circulation on each blade for minimum induced loss, analogous to the elliptic spanwise distribution of bound circulation on a wing for minimum induced drag. A propeller designed in accord with this theory has been tested in a water tunnel where it exhibited high efficiency in spite of localized cavitating flow. A knowledge of the flow field for an optimum propeller is of value to the airframe designer seeking to maximize the performance of the airplane-propeller combination.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  16. Wind and water tunnel testing of a morphing aquatic micro air vehicle.

    PubMed

    Siddall, Robert; Ortega Ancel, Alejandro; Kovač, Mirko

    2017-02-06

    Aerial robots capable of locomotion in both air and water would enable novel mission profiles in complex environments, such as water sampling after floods or underwater structural inspections. The design of such a vehicle is challenging because it implies significant propulsive and structural design trade-offs for operation in both fluids. In this paper, we present a unique Aquatic Micro Air Vehicle (AquaMAV), which uses a reconfigurable wing to dive into the water from flight, inspired by the plunge diving strategy of water diving birds in the family Sulidae. The vehicle's performance is investigated in wind and water tunnel experiments, from which we develop a planar trajectory model. This model is used to predict the dive behaviour of the AquaMAV, and investigate the efficacy of passive dives initiated by wing folding as a means of water entry. The paper also includes first field tests of the AquaMAV prototype where the folding wings are used to initiate a plunge dive.

  17. A pulse-forming network for particle path visualization. [at Ames Aeromechanics Water Tunnel Facility

    NASA Technical Reports Server (NTRS)

    Mcalister, K. W.

    1981-01-01

    A procedure is described for visualizing nonsteady fluid flow patterns over a wide velocity range using discrete nonluminous particles. The paramount element responsible for this capability is a pulse-forming network with variable inductance that is used to modulate the discharge of a fixed amount of electrical energy through a xenon flashtube. The selectable duration of the resultant light emission functions as a variable shutter so that particle path images of constant length can be recorded. The particles employed as flow markers are hydrogen bubbles that are generated by electrolysis in a water tunnel. Data are presented which document the characteristics of the electrical circuit and establish the relation of particle velocity to both section inductance and film exposure.

  18. Water-tunnel experiments on an oscillating airfoil at RE equals 21,000

    NASA Technical Reports Server (NTRS)

    Mcalister, K. W.; Carr, L. W.

    1978-01-01

    Flow visualization experiments were performed in a water tunnel on a modified NACA 0012 airfoil undergoing large amplitude harmonic oscillations in pitch. Hydrogen bubbles were used to: (1) create a conveniently striated and well preserved set of inviscid flow markers; and (2) to expose the succession of events occurring within the viscous domain during the onset of dynamic stall. Unsteady effects were shown to have an important influence on the progression of flow reversal along the airfoil surface prior to stall. A region of reversed flow underlying a free shear layer was found to momentarily exist over the entire upper surface without any appreciable disturbance of the viscous-inviscid boundary. A flow protuberance was observed to develop near the leading edge, while minor vortices evolve from an expanding instability of the free shear layer over the rear portion of the airfoil. The complete breakdown of this shear layer culminates in the successive formation of two dominant vortices.

  19. Comparing Chitin And Organic Substrates On The National Tunnel Waters In BlackHawk, Colorado For Manganese Removal

    EPA Science Inventory

    The National Tunnel is a part of the Central City/Idaho Springs Superfund site. Because passive treatment is an important possibility for removal of contaminants from the water, the USEPA and the Colorado Division of Public Health and Environment (CDPHE) have been sponsoring a ...

  20. Comparing Chitin And Organic Substrates On The National Tunnel Waters In BlackHawk, Colorado For Manganese Removal - (Presentation)

    EPA Science Inventory

    The National Tunnel is a part of the Central City/Idaho Springs Superfund site. Because passive treatment is an important possibility for removal of contaminants from the water, the USEPA and the Colorado Division of Public Health and Environment (CDPHE) have been sponsoring a ...

  1. The effects of pumpage, irrigation return, and regional ground-water flow on the water quality at Waiawa water tunnel, Oahu, Hawaii

    USGS Publications Warehouse

    Eyre, P.R.

    1983-01-01

    Waiawa shaft is a 1,700-foot long water tunnel which draws water from the top of the Pearl Harbor Ghyben-Herzberg ground-water lens, Oahu, Hawaii. The application of brackish irrigation water to sugarcane fields overlying Waiawa shaft, combined with relatively low pumping rates at the shaft from 1978 to 1980, caused the chloride concentration of water produced by Waiawa shaft to rise to 290 milligrams per liter. Time-series analyses, pumping tests and analyses of water samples show that a zone of degraded water lies at the top of the lens. This zone is mixed in significantly different proportions with the underlying fresher water depending on the pumping rate at Waiawa shaft. The chloride concentration of water in the Waiawa shaft can generally be kept below 250 milligrams per liter for the next few years, if pumping rates of about 15 million gallons per day are maintained. The use of managed pumping to control the chloride problem over the long term is uncertain owing to the possible increase in chloride concentration of the irrigation water. Based on ground-water flow rates and analogy to nearby wells, the chloride concentration of Waiawa shaft 's water will decrease to less than 100 milligrams per liter in 2 to 3 years if the use of brackish irrigation water is discontinued. (USGS)

  2. Non-rigid Group Theory, Tunneling Splittings and Nuclear Spin Statistics of Water Pentamer: (H2O5)

    SciTech Connect

    Balasubramanian, K

    2004-02-02

    The character table of the fully non-rigid water pentamer, (H{sub 2}O){sub 5} is derived for the first time. The group of all feasible permutations is the wreath product group S{sub 5}[S{sub 2}] and it consists of 3840 operations divided into 36 conjugacy classes and irreducible representations. We have shown that the full character table can be constructed using elegant matrix type generator algebra. The character table has been applied to the water pentamer by obtaining the nuclear spin statistical weights of the rovibronic levels and tunneling splittings of the fully non-rigid pentamer. We have also obtained the statistical weights and tunneling splittings of a semi-rigid deuterated pentamer that exhibits pseudo rotation with an averaged C{sub 5h}(G{sub 10}) symmetry used in the assignment of vibration-rotation-tunneling spectra . The correlation tables have been constructed for the semirigid (G{sub 10}) to non-rigid (G{sub 3840}) groups for the rotational levels and tunneling levels. The nuclear spin statistical weights have also been derived for both the limits.

  3. Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules

    PubMed Central

    Davidge, Kelly S; Singh, Sandip; Bowman, Lesley AH; Tinajero-Trejo, Mariana; Carballal, Sebastián; Radi, Rafael; Poole, Robert K; Dikshit, Kanak; Estrin, Dario A; Marti, Marcelo A; Boechi, Leonardo

    2015-01-01

    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 O 2 and •NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels that are partially blocked by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify •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, •NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations introduce modifications in both tunnel topologies and affect the incoming ligand capacity to displace retained water molecules at the active site. 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. PMID:26478812

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

    DTIC Science & Technology

    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

  5. Water tunnel flow visualization study of a 4.4 percent scale X-31 forebody

    NASA Technical Reports Server (NTRS)

    Cobleigh, Brent R.; Delfrate, John

    1994-01-01

    A water-tunnel test of a 4.4 percent-scale, forebody-only model of the X-31 aircraft with different forebody strakes and nosebooms has been performed in the Flow Visualization Facility at the NASA Dryden Flight Research Center. The focus of the study was to determine the relative effects of the different configurations on the stability and symmetry of the high-angle-of-attack forebody vortex flow field. The clean, noseboom-off configuration resisted the development of asymmetries in the primary vortices through 70 deg angle of attack. The wake of the X-31 flight test noseboom configuration significantly degraded the steadiness of the primary vortex cores and promoted asymmetries. An alternate L-shaped noseboom mounted underneath the forebody had results similar to those seen with the configuration, enabling stable, symmetrical vortices up to 70 deg angle of attack. The addition of strakes near the radome tip along the waterline increased the primary vortex strength while it simultaneously caused the vortex breakdown location co move forward. Forebody strakes did not appear to significantly reduce the asymmetries in the forebody vortex field in the presence of the flight test noseboom.

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

    NASA Technical Reports Server (NTRS)

    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.

  7. Preliminary analysis of the hydrologic effects of temporary shutdowns of the Rondout-West Branch Water Tunnel on the groundwater-flow system in Wawarsing, New York

    USGS Publications Warehouse

    Stumm, Frederick; Chu, Anthony; Como, Michael D.; Noll, Michael L.

    2012-01-01

    Flooding of streets and residential basements, and bacterial contamination of private-supply wells with Escherichia coli (E. coli) are recurring problems in the Rondout Valley near the Town of Wawarsing, Ulster County, New York. Leakage from the Rondout-West Branch (RWB) Water Tunnel and above-normal precipitation have been suspected of causing elevated groundwater levels and basement flooding. The hydrology of a 12-square-mile study area within the Town of Wawarsing was studied during 2008-10. A network of 41 wells (23 unconsolidated-aquifer and 18 bedrock wells) and 2 surface-water sites was used to monitor the hydrologic effects of four RWB Water Tunnel shutdowns. The study area is underlain by a sequence of northeast-trending sedimentary rocks that include limestone, shale, and sandstone. The bedrock contains dissolution features, fractures, and faults. Inflows that ranged from less than 1 to more than 9,000 gallons per minute from the fractured bedrock were documented during construction of the 13.5-foot-diameter RWB Water Tunnel through the sedimentary-rock sequence 710 feet (ft) beneath the study-area valley. Glacial sediments infill the valley above the bedrock sequence and consist of clay, silt, sand, and gravel. The groundwater-flow system in the valley consists of both fractured-rock and unconsolidated aquifers. Water levels in both the bedrock and unconsolidated aquifers respond to variations in seasonal precipitation. During the past 9 years (2002-10), annual precipitation at Central Park, N.Y., has exceeded the 141-year mean. Potentiometric-surface maps indicate that groundwater in the bedrock flows from the surrounding hills on the east and west sides of the valley toward the center of the valley, and ultimately toward the northeast. On average, water levels in the bedrock aquifer had seasonal differences of 5.3 ft. Analysis of hydrographs of bedrock wells indicates that many of these wells are affected by the RWB Tunnel leakage. Tunnel

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

    NASA Technical Reports Server (NTRS)

    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.

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

    SciTech Connect

    Fontaine, Arnold A.; Straka, William A.; Meyer, Richard S.; Jonson, Michael L.

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

    SciTech Connect

    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.

  11. The construction and operation of a water tunnel in application to flow visualization studies of an oscillating airfoil

    NASA Technical Reports Server (NTRS)

    Olsen, J. H.; Liu, H. T.

    1973-01-01

    The water tunnel which was constructed at the NASA Ames Research Center is described along with the flow field adjacent to an oscillating airfoil. The design and operational procedures of the tunnel are described in detail. Hydrogen bubble and thymol blue techniques are used to visualize the flow field. Results of the flow visualizations are presented in a series of still pictures and a high speed movie. These results show that time stall is more complicated than simple shedding from the leading edge or the trailing edge, particularly at relatively low frequency oscillations comparable to those of a helicopter blade. Therefore, any successful theory for predicting the stall loads on the helicopter blades must treat an irregular separated region rather than a discrete vortex passing over each blade surface.

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

    PubMed

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

    2017-03-21

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. The Aerodynamic Performance of the 24 Inch Houck Configuration

    DTIC Science & Technology

    2007-03-01

    8 2.5 Winglets ... Winglets “ Winglets are aerodynamic components, placed at the tip of a wing to improve its efficiency during cruise” (6). The purpose of the winglet ...reduction in downwash, and therefore the induced drag (20; 11:1). Properly designed winglets can reduce overall drag, increase lift, provide added stability

  15. Use of advanced borehole geophysical techniques to delineate fractured-rock ground-water flow and fractures along water-tunnel facilities in northern Queens County, New York

    USGS Publications Warehouse

    Stumm, Frederick; Chu, Anthony; Lange, Andrew D.; Paillet, Frederick L.; Williams, John H.; Lane, John W.

    2001-01-01

    Advanced borehole geophysical methods were used to assess the geohydrology of crystalline bedrock along the course of a new water tunnel for New York City. The logging methods include natural gamma, spontaneous potential, single-point resistance, mechanical and acoustic caliper, focused electromagnetic induction, electromagnetic resistivity, magnetic susceptibility, borehole-fluid temperature and conductance, differential temperature, heat-pulse flowmeter, acoustic televiewer, borehole deviation, optical televiewer, and borehole radar. Integrated interpretation of the geophysical logs from an 825-foot borehole (1) provided information on the extent, orientation, and structure (foliation and fractures) within the entire borehole, including intensely fractured intervals from which core recovery may be poor; (2) delineated transmissive fracture zones intersected by the borehole and provided estimates of their transmissivity and hydraulic head; and (3) enabled mapping of the location and orientation of structures at distances as much as 100 ft from the borehole.Analyses of the borehole-wall image and the geophysical logs from the borehole on Crescent Street, in northern Queens County, are presented here to illustrate the application of the methods. The borehole penetrates gneiss and other crystalline bedrock that has predominantly southeastward dipping foliation and nearly horizontal and southeastward-dipping fractures. The heat-pulse flowmeter logs obtained under pumping and nonpumping conditions, together with the other geophysical logs, indicate five transmissive fracture zones. More than 90 percent of the open-hole transmissivity is associated with a fracture zone 272 feet BLS (below land surface). A transmissive zone at 787 feet BLS that consists of nearly parallel fractures lies within the projected tunnel path; here the hydraulic head is 12 to 15 feet lower than that of transmissive zones above the 315-foot depth. The 60-megahertz directional borehole radar logs

  16. Use of advanced borehole geophysical techniques to delineate fractured-rock ground-water flow and fractures along water-tunnel facilities in northern Queens County, New York

    USGS Publications Warehouse

    Stumm, Frederick; Chu, Anthony; Lange, Andrew D.; Paillet, Frederick L.; Lane,, John W.

    2001-01-01

    Advanced borehole geophysical methods were used to assess the geohydrology of crystalline bedrock along the course of a new water tunnel for New York City. The logging methods include natural gamma, spontaneous potential, single-point resistance, mechanical and acoustic caliper, focused electromagnetic induction, electromagnetic resistivity, magnetic susceptibility, borehole-fluid temperature and conductance, differential temperature, heat-pulse flowmeter, acoustic televiewer, borehole deviation, optical televiewer, and borehole radar. Integrated interpretation of the geophysical logs from an 825-foot borehole (1) provided information on the extent, orientation, and structure (foliation and fractures) within the entire borehole, including intensely fractured intervals from which core recovery may be poor; (2) delineated transmissive fracture zones intersected by the borehole and provided estimates of their transmissivity and hydraulic head; and (3) enabled mapping of the location and orientation of structures at distances as much as 100 ft from the borehole. Analyses of the borehole-wall image and the geophysical logs from the borehole on Crescent Street, in northern Queens County, are presented here to illustrate the application of the methods. The borehole penetrates gneiss and other crystalline bedrock that has predominantly southeastward dipping foliation and nearly horizontal and southeastward-dipping fractures. The heat-pulse flowmeter logs obtained under pumping and nonpumping conditions, together with the other geophysical logs, indicate five transmissive fracture zones. More than 90 percent of the open-hole transmissivity is associated with a fracture zone 272 feet BLS (below land surface). A transmissive zone at 787 feet BLS that consists of nearly parallel fractures lies within the projected tunnel path; here the hydraulic head is 12 to 15 feet lower than that of transmissive zones above the 315-foot depth. The 60-megahertz directional borehole radar

  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

    USGS Publications Warehouse

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

    NASA Astrophysics Data System (ADS)

    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?

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

    DTIC Science & Technology

    2012-12-01

    Jan. Jarrah, M-A. M. 1989 Low-speed wind-tunnel investigation of the flow about delta wing , oscillating in pitch to very high angle of attack...investigation of unsteady vortex flow for a pitching -rolling 70 delta wing . Paper 98-0416, AIAA 36th Aerospace Sciences Meeting and Exhibit. Kramer, B. R...LeMay, S. P., Batill, S. M. & Nelson, R. C. 1990 Vortex dynamics on a pitching delta wing . J. Aircraft, Vol. 27., No. 2, Feb. Lowson, M. V

  20. Hydrogeochemistry of seepage water collected within the Youngcheon diversion tunnel, Korea: source and evolution of SO4-rich groundwater in sedimentary terrain

    NASA Astrophysics Data System (ADS)

    Chae, Gi-Tak; Yun, Seong-Taek; Kim, Sang-Ryul; Hahn, Chan

    2001-06-01

    In the Youngcheon Diversion Tunnel area, South Korea, 46 samples of tunnel seepage water (TSW) and borehole groundwater were collected from areas with sedimentary rocks (mainly sandstone and shale) and were examined for hydrogeochemical characteristics. The measured SO4 concentrations range widely from 7·7 to 942·0 mg/l, and exceed the Korean Drinking Water Standard (200 mg/l) in about half the samples. The TDS (total dissolved solid) content generally is high (171-1461 mg/l) from more shale-rich formations and also reflects varying degrees of water-rock interaction. The water is classified into three groups: Ca SO4 type (61% of the samples collected), Ca SO4 HCO3 type (15%) and Ca HCO3 type (24%). The Ca HCO3 type water (mean concentrations=369 mg/l Ca, 148 mg/l HCO3 and 23 mg/l SO4) reflected the simple reaction between CO2-recharged water and calcite, whereas the more SO4-rich nature of Ca SO4 type water (mean concentrations=153 mg/l Ca, 66 mg/l HCOtunnel as well as in high concentrations of Ca (mean 153 mg/l) and Na (mean 49 mg/l) for TSW, and is associated with calcite dissolution resulting in pH buffering. The pyrite oxidation required for the formation of Ca SOwater was enhanced by the diffusion of oxygenated air through the fractures related to the tunnel's construction. The subsequent outgassing of COtunnel resulted in precipitation of iron-bearing carbonate.

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

    PubMed

    Serrano, Giulia; Bonanni, Beatrice; Kosmala, Tomasz; Di Giovannantonio, Marco; Diebold, Ulrike; Wandelt, Klaus; Goletti, Claudio

    2015-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  3. Wind Tunnel Investigation of a Balloon as Decelerator at Mach Numbers from 1.47 to 2.50

    NASA Technical Reports Server (NTRS)

    1961-01-01

    Wind Tunnel Investigation of a Balloon as Decelerator at Mach Numbers from 1.47 to 2.50. A wind-tunnel investigation was conducted to study the characteristics of a towed spherical balloon as a drag device at Mach numbers from 1.47 to 2.50, Reynolds numbers from 0.36 x 10(exp 6) to 1.0 x 10(exp 6) , and angles of attack from -15 to 15 degrees. Tow-cable length was approximately 24 inches from asymmetric body to cone on the upstream side of the balloon. As the tow cable was lengthened the balloon reached a point in the test section where wall-reflected shocks intersected the balloon and caused severe oscillations. As a result, the tow cable broke and the inflatable balloon model was destroyed. Further tests used a model rigid plastic sphere 6.75 inches in diameter. Tow cable length was approximately 24 inches from asymmetric body to the upstream side of the sphere. [Entire movie available on DVD from CASI as Doc ID 20070030967. Contact help@sti.nasa.gov

  4. Numerical modeling of water spray suppression of conveyor belt fires in a large-scale tunnel.

    PubMed

    Yuan, Liming; Smith, Alex C

    2015-05-01

    Conveyor belt fires in an underground mine pose a serious life threat to miners. Water sprinkler systems are usually used to extinguish underground conveyor belt fires, but because of the complex interaction between conveyor belt fires and mine ventilation airflow, more effective engineering designs are needed for the installation of water sprinkler systems. A computational fluid dynamics (CFD) model was developed to simulate the interaction between the ventilation airflow, the belt flame spread, and the water spray system in a mine entry. The CFD model was calibrated using test results from a large-scale conveyor belt fire suppression experiment. Simulations were conducted using the calibrated CFD model to investigate the effects of sprinkler location, water flow rate, and sprinkler activation temperature on the suppression of conveyor belt fires. The sprinkler location and the activation temperature were found to have a major effect on the suppression of the belt fire, while the water flow rate had a minor effect.

  5. Numerical modeling of water spray suppression of conveyor belt fires in a large-scale tunnel

    PubMed Central

    Yuan, Liming; Smith, Alex C.

    2015-01-01

    Conveyor belt fires in an underground mine pose a serious life threat to miners. Water sprinkler systems are usually used to extinguish underground conveyor belt fires, but because of the complex interaction between conveyor belt fires and mine ventilation airflow, more effective engineering designs are needed for the installation of water sprinkler systems. A computational fluid dynamics (CFD) model was developed to simulate the interaction between the ventilation airflow, the belt flame spread, and the water spray system in a mine entry. The CFD model was calibrated using test results from a large-scale conveyor belt fire suppression experiment. Simulations were conducted using the calibrated CFD model to investigate the effects of sprinkler location, water flow rate, and sprinkler activation temperature on the suppression of conveyor belt fires. The sprinkler location and the activation temperature were found to have a major effect on the suppression of the belt fire, while the water flow rate had a minor effect. PMID:26190905

  6. Design of a closed system water tunnel for lamprey swimming analysis.

    PubMed

    McIntosh, C M; Knapp, C F; Jung, R

    1997-01-01

    This work presents a swim mill design that can be used to study locomotor behavior in intact awake lamprey. The design is constrained by the swimming characteristics and anatomy of young adult lamprey and allows for electrophysiological monitoring of muscle activity and imaging of motor behavior. The design has a test section for animal containment and monitoring of motor behavior, a water reservoir, a water pump, and equipment for biological adaptations (water purification, chilling, & aeration systems). The 36 sq. inch acrylic test section is preceded by a turbulence-reducing converging nozzle, while a 1400 gallon reservoir maintains the system's hydrostatic head and acts as a settling chamber. This swim mill design will be used to examine lamprey swimming behavior under different environmental conditions (e.g., water velocity, turbulence, external perturbations).

  7. 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

    NASA Astrophysics Data System (ADS)

    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.

  8. Water-tunnel study results of a TF/A-18 and F/A-18 canopy flow visualization

    NASA Technical Reports Server (NTRS)

    Johnson, Steven A.; Fisher, David F.

    1990-01-01

    A water tunnel study examining the influence of canopy shape on canopy and leading edge extension flow patterns was initiated. The F/A-18 single-place canopy model and the TF/A-18 two place canopy model were the study subjects. Plan view and side view photographs showing the flow patterns created by injected colored dye are presented for 0 deg and 5 deg sideslip angles. Photographs taken at angle of attack and sideslip conditions correspond to test departure points found in flight test. Flight experience has shown that the TF/A-18 airplane departs in regions where the F/A-18 airplane is departure-resistant. The study results provide insight into the differences in flow patterns which may influence the resulting aerodynamics of the TF/A-18 and F/A-18 aircraft. It was found that at 0 deg sideslip, the TF/A-18 model has more downward flow on the sides of the canopy than the F/A-18 model. This could be indicative of flow from the leading edge extension (LEX) vortexes impinging on the sides of the wider TF/A-18 canopy. In addition, the TF/A-18 model has larger areas of asymmetric separated and unsteady flow on the LEXs and fuselage, possibly indicating a lateral and directional destabilizing effect at the conditions studied.

  9. Fish and Robots Swimming Together in a Water Tunnel: Robot Color and Tail-Beat Frequency Influence Fish Behavior

    PubMed Central

    Polverino, Giovanni; Phamduy, Paul; Porfiri, Maurizio

    2013-01-01

    The possibility of integrating bioinspired robots in groups of live social animals may constitute a valuable tool to study the basis of social behavior and uncover the fundamental determinants of animal functions and dysfunctions. In this study, we investigate the interactions between individual golden shiners (Notemigonus crysoleucas) and robotic fish swimming together in a water tunnel at constant flow velocity. The robotic fish is designed to mimic its live counterpart in the aspect ratio, body shape, dimension, and locomotory pattern. Fish positional preference with respect to the robot is experimentally analyzed as the robot's color pattern and tail-beat frequency are varied. Behavioral observations are corroborated by particle image velocimetry studies aimed at investigating the flow structure behind the robotic fish. Experimental results show that the time spent by golden shiners in the vicinity of the bioinspired robotic fish is the highest when the robot mimics their natural color pattern and beats its tail at the same frequency. In these conditions, fish tend to swim at the same depth of the robotic fish, where the wake from the robotic fish is stronger and hydrodynamic return is most likely to be effective. PMID:24204882

  10. Fish and robots swimming together in a water tunnel: robot color and tail-beat frequency influence fish behavior.

    PubMed

    Polverino, Giovanni; Phamduy, Paul; Porfiri, Maurizio

    2013-01-01

    The possibility of integrating bioinspired robots in groups of live social animals may constitute a valuable tool to study the basis of social behavior and uncover the fundamental determinants of animal functions and dysfunctions. In this study, we investigate the interactions between individual golden shiners (Notemigonus crysoleucas) and robotic fish swimming together in a water tunnel at constant flow velocity. The robotic fish is designed to mimic its live counterpart in the aspect ratio, body shape, dimension, and locomotory pattern. Fish positional preference with respect to the robot is experimentally analyzed as the robot's color pattern and tail-beat frequency are varied. Behavioral observations are corroborated by particle image velocimetry studies aimed at investigating the flow structure behind the robotic fish. Experimental results show that the time spent by golden shiners in the vicinity of the bioinspired robotic fish is the highest when the robot mimics their natural color pattern and beats its tail at the same frequency. In these conditions, fish tend to swim at the same depth of the robotic fish, where the wake from the robotic fish is stronger and hydrodynamic return is most likely to be effective.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Rotational Spectrum of the Methyl Salicylate-Water Complex: the Missing Conformer and the Tunneling Motions

    NASA Astrophysics Data System (ADS)

    Ghosh, Supriya; Thomas, Javix; Xu, Yunjie; Jäger, Wolfgang

    2015-06-01

    Methyl salicylate is a naturally occurring organic ester produced by wintergreen and other plants. It is also found in many over-the-counter remedies, such as muscle ache creams. The rotational spectrum of the methyl salicylate monomer was reported previously, where the most stable, dominant conformer was identified. The methyl salicylate-water complex was first studied using fluorescence-detected infrared spectroscopy; only one monohydrate conformer was found in that work. In the present study, we employed both broadband chirped and cavity based Fourier transform microwave spectroscopy to examine the competition between intra- and intermolecular hydrogen-bonding interactions and possible large amplitude motions associated with the methyl group and the water subunit. In contrast to the previous infrared study, two monohydrate conformers were identified, with carbonyl O or hydroxyl O as the hydrogen bond acceptors. Detailed analyses of the observed hyperfine structures will be presented, as well as our efforts to extend the study to larger methyl salicylate hydration clusters. S. Melandri, B. M. Giuliano, A. Maris, L. B. Favero, P. Ottaviani, B. Velino, W. Caminati, J. Phys. Chem. A. 2007, 111, 9076. A. Mitsuzuka, A. Fujii, T. Ebata, N. Mikami, J. Phys. Chem. A 1998, 102, 9779.

  13. Early Childhood: Funnels and Tunnels.

    ERIC Educational Resources Information Center

    Fowlkes, Mary Anne

    1985-01-01

    Suggests using funnels and tunnels in combination with water, blocks, transportation toys, and other materials to help teach preschoolers to make predictions. Many examples are included for using funnels to understand properties of liquids and for using tunnels to predict order. (DH)

  14. Measurement of Steady and Unsteady Duct Loads for Propeller 4381 at Crashback Conditions in the 36 in. Water Tunnel

    DTIC Science & Technology

    2010-08-01

    flow. It was concluded that cavitation was responsible for the discrepancy. Davoudzadeh (4) used RANS to simulate flow over the entire submarine... Cavitation Tunnel. The facility is a vertical plane, closed re-circulating tunnel with resorber, variable-speed, variable-pressure, two... screw terminal connection block (NI part number SCB-68). All data were sampled at a rate of 500 Hz. Previous crashback testing efforts determined this

  15. Shape and oscillations of the water drops freely suspended in a horizontal electric field: A wind tunnel study

    NASA Astrophysics Data System (ADS)

    Bhalwankar, Rohini; Deshpande, C. G.; Kamra, A. K.

    2015-10-01

    The time-averaged axis ratios, frequency and amplitude of oscillations of water drops of 2.67-6.6 mm diameter were determined by suspending them in a vertical wind tunnel in the absence and presence of horizontal electric fields using a high speed camera at 1000 frames per second. A systematic decrease in the drop's axis-ratio is observed with increase in its diameter and/or horizontal electric field. The results revealed with high speed photography are in good agreement with earlier results. The drop distortion due to horizontal electric field is more pronounced for the drops in the size-range of 3.36-6 mm diameter showing that the electrical forces progressively enhance the horizontal elongation of the drop resulting in its instability at 6.6 mm. The drop oscillation frequency computed from temporal variation of axis ratio, decreases with increase in drop size but shows no significant change in oscillation frequency in the horizontal electric field of ≤500 kV m-1. However, the oscillation amplitude increases with increase in drop size up to a threshold value and then flatten-off in the electric field of ≤300 kV m-1 demonstrating the nonlinear effect of net forces acting on such large drops. In higher electric field of 500 kV m-1, gradual increase in the amplitude of oscillation with an increase in drop diameter has been observed. Moreover, for a particular drop size, the amplitude of oscillation decreases with increase in the electric field upto 500 kV m-1. The oscillation frequency of the waterdrops experiences multimode oscillations. The dominant fundamental mode of oscillations (2,0) always exists for all drops in our experiments along with the coexistence of higher modes of oscillations i.e. (2,1) and (2,2) mode. Possible effects of electrical forces on shape parameters and their implications on cloud microphysics and in radar meteorology are discussed.

  16. Surface species formed by the adsorption and dissociation of water molecules on Ru(0001) surface containing a small coverage of carbon atoms studied by scanning tunneling microscopy

    SciTech Connect

    Dept of Materials Science and Engineering UCB; Dept of Applied Science and Technology, UCB; Institut de Ciencia de Materials de Barcelona, Barcelona, Spain; Instituto de Ciencia de Materiales de Madrid, Madrid, Spain; Department of Mechanical Engineering, Yale University; Salmeron, Miquel; Shimizu, Tomoko K.; Mugarza, Aitor; Cerda, Jorge I.; Heyde, Markus; Qi, Yabing; Schwarz, Udo D.; Ogletree, D. Frank; Salmeron, Miquel

    2008-04-26

    The adsorption and dissociation of water on a Ru(0001) surface containing a small amount ({le} 3 %) of carbon impurities was studied by scanning tunneling microscopy (STM). Various surface species are formed depending on the temperature. These include molecular H{sub 2}O, H{sub 2}O-C complexes, H, O, OH and CH. Clusters of either pure H{sub 2}O or mixed H{sub 2}O-OH species are also formed. Each of these species produces a characteristic contrast in the STM images and can be identified by experiment and by ab initio total energy calculations coupled with STM image simulations. Manipulation of individual species via excitation of vibrational modes with the tunneling electrons has been used as supporting evidence.

  17. Hydrogeologic controls on ground-water discharge to the Washington METRO subway tunnel near the Medical Center station and Crossover, Montgomery County, Maryland

    USGS Publications Warehouse

    Greene, Earl A.; Shapiro, Allen M.; LaMotte, Andrew E.

    2004-01-01

    Excessive water intrusion has been observed inside several of the Washington Metropolitan Area Transit Authority subway tunnels, with the worst leakage occurring along the Red Line tunnels and stations north of Dupont Circle in Washington, D.C. These tunnels were constructed in bedrock that contains permeable (water-bearing) joints and fractures. Excessive water leakage through the walls and water inside the underground facilities has damaged mechanical and electrical components in the tunnel, and has escalated the deterioration rate of the rail system. The U.S. Geological Survey and the Washington Metropolitan Area Transit Authority have worked cooperatively on a study from 200003 to describe and quantify the factors controlling ground-water flow into the Red Line subway tunnel near the Medical Center Station and Crossover in Montgomery County, Maryland. The Red Line near the Medical Center Station and Crossover passes through or beneath the gneissic Sykesville Formation and the biotite-hornblende tonalite member of the Georgetown Intrusive Suite, both of which contain numerous fractures. The mapped foliation and joints of the Sykesville Formation in the vicinity of the Medical Center Station and Crossover are generally orientated north-south. Fractures in the Sykesville Formation in outcrops appear to be poorly connected. In the biotite-hornblende tonalite member of the Georgetown Intrusive Suite, the general orientation of the mapped foliation and joints is east-west. In contrast to the fractures in the Sykesville Formation, the fractures in the Georgetown Intrusive Suite in outcrops appear to be more numerous and have a greater degree of connectivity. Fractures intersecting four bedrock wells near the Medical Center Station and Crossover that were drilled into the biotite-hornblende tonalite member of the Georgetown Intrusive Suite show an east-west orientation matching the foliation and joints shown on geologic maps. The excessive water intrusion at the

  18. Recognition Tunneling

    PubMed Central

    Lindsay, Stuart; He, Jin; Sankey, Otto; Hapala, Prokop; Jelinek, Pavel; Zhang, Peiming; Chang, Shuai; Huang, Shuo

    2010-01-01

    Single molecules in a tunnel junction can now be interrogated reliably using chemically-functionalized electrodes. Monitoring stochastic bonding fluctuations between a ligand bound to one electrode and its target bound to a second electrode (“tethered molecule-pair” configuration) gives insight into the nature of the intermolecular bonding at a single molecule-pair level, and defines the requirements for reproducible tunneling data. Simulations show that there is an instability in the tunnel gap at large currents, and this results in a multiplicity of contacts with a corresponding spread in the measured currents. At small currents (i.e. large gaps) the gap is stable, and functionalizing a pair of electrodes with recognition reagents (the “free analyte” configuration) can generate a distinct tunneling signal when an analyte molecule is trapped in the gap. This opens up a new interface between chemistry and electronics with immediate implications for rapid sequencing of single DNA molecules. PMID:20522930

  19. The Effect of Developing a Tunnel across a Highway on the Water Quality in an Upstream Reservoir Watershed Area—A Case Study of the Hsuehshan Tunnel in Taiwan

    PubMed Central

    Shyu, Guey-Shin; Cheng, Bai-You; Fang, Wi-Ta

    2012-01-01

    Cities in Taiwan are so dependent on reservoir water that preservation of the upstream reservoir watershed has become a significant public concern. However, due to the high-density development of land, resulting in rapid urban expansion, the construction of tunnels and elevated highways across reservoirs to better utilize the surrounding land has become a global trend. Based on data from long-term observation of the reservoir, this study verifies the difference in water quality before and after the highway construction. The results indicate that the total phosphorus (TP) increased on average 14 μg/L to 36.5 μg/L per annum, and the water quality is expected to require 10 years to recover. During the highway development, the average TP was more than twice the normal level. During summer, the TP level increases 3.1-fold due to rainfall. As indicated by the results, the large-scale land development will harm the long-term preservation of the reservoir’s water quality, and therefore should be avoided. PMID:23202691

  20. The effect of developing a tunnel across a highway on the water quality in an upstream reservoir watershed area--a case study of the Hsuehshan tunnel in Taiwan.

    PubMed

    Shyu, Guey-Shin; Cheng, Bai-You; Fang, Wei-Ta

    2012-09-19

    Cities in Taiwan are so dependent on reservoir water that preservation of the upstream reservoir watershed has become a significant public concern. However, due to the high-density development of land, resulting in rapid urban expansion, the construction of tunnels and elevated highways across reservoirs to better utilize the surrounding land has become a global trend. Based on data from long-term observation of the reservoir, this study verifies the difference in water quality before and after the highway construction. The results indicate that the total phosphorus (TP) increased on average 14 μg/L to 36.5 μg/L per annum, and the water quality is expected to require 10 years to recover. During the highway development, the average TP was more than twice the normal level. During summer, the TP level increases 3.1-fold due to rainfall. As indicated by the results, the large-scale land development will harm the long-term preservation of the reservoir's water quality, and therefore should be avoided.

  1. 4. East portal of Tunnel 22, view to the eastsoutheast, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. East portal of Tunnel 22, view to the east-southeast, 135mm lens with electronic flash fill. Note the depth of water within the tunnel, a sympton of the spring-laden slope above the tunnel that led to its eventual abandonment. - Southern Pacific Railroad Natron Cutoff, Tunnel 23, Milepost 584.5, Westfir, Lane County, OR

  2. Climate and Antartic Intermediate Water Covariations on Centennial-Millennial Timescales during MIS 3—Constraining the Role of the "Oceanic Tunnel" in Abrupt Climate Change.

    NASA Astrophysics Data System (ADS)

    Kleiven, H. F.; Ninnemann, U.

    2014-12-01

    The equatorward ventilation of Southern Hemisphere extratropical water masses to the low latitude thermocline has been proposed as a window through which the high latitude ocean can modulate tropical climate on anything from decadal to orbital timescales. This hypothesis is founded largely on the observation that tropical thermocline waters originate mostly in the Southern Hemisphere and that computer simulations suggest property anomalies in these source regions can advect through the intermediate ocean, "the ocean tunnel" to influence tropical SST. However, few observational records of extratropical ocean changes are available to assess their impacts on multi-decadal and longer timescales. Here we add to the observational record using new decadally resolved planktonic and benthic foraminiferal isotopic records spanning MIS 3 (20-50 ka) from the Chilean slope ODP Site 1233 that is located on the northern margin of the Antarctic Circumpolar Current and its seafloor lies in the core of Antarctic Intermediate Water (AAIW). Thus the site is ideally situated to reconstruct both near surface and AAIW variability in the high southern latitudes. On centennial to millennial timescales, changes in intermediate water properties track those in the near surface albeit with a reduced amplitude—confirming the idea that changes in the extratropical ocean effect the oceanic tunnel on these timescales. The new benthic and plantic foraminiferal isotope results demonstrate that variations in intermediate ocean properties and climate of the southeast Pacific closely align with those recorded in the EPICA ice core from Dronning Maud Land. Such abrupt, synoptic scale changes in Antarctic climate and dynamics will have potentially widespread climatic and biogeochemical consequences along the downstream flowpath of AAIW. The broad coherence of the observed Antarctic signal supports the concept of hemispheric thermal asynchrony on millennial timescales, and the extension of this climate

  3. Numerical-assisted design of a wind tunnel used in the estimation of volatilization from water, waste or soil.

    PubMed

    Baléo, J N; Le Cloirec, P

    2006-04-01

    Numerical simulations of the flow inside two wind tunnel geometries used for determining emission volatilization have been conducted. The flow pattern was examined in a plane close to the emitting surface. A reduced surface, characterizing the low velocity zones in this plane, has been defined. The proposed geometry modification, consisting of a convergent/divergent system, decreases the low velocity regions by a factor ranging between 2 and 3.5. Large vortices present in the conventional configuration are almost eliminated. The new velocity distribution, close to the emitting surface, is more uniform and should therefore generate a more efficient mass transfer to the flowing air.

  4. Gas-phase ammonia and water-soluble ions in particulate matter analysis in an urban vehicular tunnel.

    PubMed

    Vieira-Filho, Marcelo S; Ito, Debora T; Pedrotti, Jairo J; Coelho, Lúcia H G; Fornaro, Adalgiza

    2016-10-01

    Ammonia is a key alkaline species, playing an important role by neutralizing atmospheric acidity and inorganic secondary aerosol production. On the other hand, the NH3/NH4 (+) increases the acidity and eutrophication in natural ecosystems, being NH3 classified as toxic atmospheric pollutant. The present study aims to give a better comprehension of the nitrogen content species distribution in fine and coarse particulate matter (PM2.5 and PM2.5-10) and to quantify ammonia vehicular emissions from an urban vehicular tunnel experiment in the metropolitan area of São Paulo (MASP). MASP is the largest megacity in South America, with over 20 million inhabitants spread over 2000 km(2) of urbanized area, which faces serious environmental problems. The PM2.5 and PM2.5-10 median mass concentrations were 44.5 and 66.6 μg m(-3), respectively, during weekdays. In the PM2.5, sulfate showed the highest concentration, 3.27 ± 1.76 μg m(-3), followed by ammonium, 1.14 ± 0.71 μg m(-3), and nitrate, 0.80 ± 0.52 μg m(-3). Likewise, the dominance (30 % of total PM2.5) of solid species, mainly the ammonium salts, NH4HSO4, (NH4)2SO4, and NH4NO3, resulted from simulation of inorganic species. The ISORROPIA simulation was relevant to show the importance of environment conditions for the ammonium phase distribution (solid/aqueous), which was solely aqueous at outside and almost entirely solid at inside tunnel. Regarding gaseous ammonia concentrations, the value measured inside the tunnel (46.5 ± 17.5 μg m(-3)) was 3-fold higher than that outside (15.2 ± 11.3 μg m(-3)). The NH3 vehicular emission factor (EF) estimated by carbon balance for urban tunnel was 44 ± 22 mg km(-1). From this EF value and considering the MASP traffic characteristics, it was possible to estimate more than 7 Gg NH3 year(-1) emissions that along with NOx are likely to cause rather serious problems to natural ecosystems in the region.

  5. 20. VIEW WEST OF TUNNEL FROM BASEMENT OF GRANITEVILLE MILL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. VIEW WEST OF TUNNEL FROM BASEMENT OF GRANITEVILLE MILL TO OUTBUILDINGS. TUNNEL IS USED TO CONDUCT WATER AND OTHER UTILITY PIPES. - Graniteville Mill, Marshall Street, Graniteville, Aiken County, SC

  6. Inspection and rehabilitation of tunnels across faults

    SciTech Connect

    Abramson, L.W.; Schmidt, B.

    1995-12-31

    The inspection and rehabilitation of tunnels that cross faults is unique because they usually are in use and have a large variety of alternative lining types including bare rock, concrete, or steel often coated with accumulations of dirt, grime, algae and other minerals. Inspection methods are important including what to look for, how to clean the inner tunnel lining surfaces, non-destructive testing, coring, soundings, air quality detection and protection, ventilation, lightning, etc. Rehabilitation of tunnels crossing faults requires a practiced knowledge of underground design and construction practices. The most common methods of rehabilitation include grouting and concreting. The Variety of water, wastewater, transit, and highway tunnels in California provide ample examples of tunnels, new and old, that cross active faults. This paper will address specific methods of tunnel inspection and maintenance at fault crossings and give examples of relevant highway, transit, water, and wastewater projects and studies in California to demonstrate the discussions presented.

  7. Multisensor system for tunnel inspection

    NASA Astrophysics Data System (ADS)

    Idoux, Maurice

    2005-01-01

    The system is aimed at assisting inspection and monitoring of the degradation of tunnels in order to minimize maintenance and repair time. ATLAS 70 is a complete sensors/software package which enables thorough diagnosis of tunnel wall conditions. The data collected locally are stored on a computer hard disk for subsequent analysis in a remote location via elaborate dedicated software. The sensors and local computer are loaded onto a rail and/or road vehicle of specific design, i.e. with even travelling speed of 2 to 5 km/h. Originally, the system has been developed for the Paris Underground Company and has since been applied to rail and road tunnels, large town sewage systems, clean water underground aqueducts and electric cable tunnels.

  8. Tunnel-to-tunnel correlation

    NASA Technical Reports Server (NTRS)

    Steinle, F. W., Jr.

    1982-01-01

    Flow quality is discussed. Incremental comparisons of: (1) the angle of attack, (2) the axial force coefficient, and (3) the base cavity axial force coefficient against the normal force coefficient are presented. Relative blockage determination, relative buoyancy corrections, and boundary layer transition length are discussed. Blockage buoyancy caused by tunnel model wall dynamic interaction is discussed in terms of adaptive walls. The effect of 'transonic turbulence factor' is considered.

  9. Carpal Tunnel Syndrome

    MedlinePlus

    ... Just a passing cramp? It could be carpal tunnel syndrome. The carpal tunnel is a narrow passageway of ligament and bones ... from irritated tendons or other swelling narrows the tunnel and causes the nerve to be compressed. Symptoms ...

  10. Looking into Tunnel Books.

    ERIC Educational Resources Information Center

    Hinshaw, Craig

    1999-01-01

    Describes how to make tunnel books, which are viewed by looking into a "tunnel" created by accordion-folded expanding sides. Suggests possible themes. Describes how to create a walk-through tunnel book for first grade students. (CMK)

  11. Seismic prediction ahead of tunnel constructions

    NASA Astrophysics Data System (ADS)

    Jetschny, S.; Bohlen, T.; Nil, D. D.; Giese, R.

    2007-12-01

    To increase safety and efficiency of tunnel constructions, online seismic exploration ahead of a tunnel can become a valuable tool. Within the \\it OnSite project founded by the BMBF (German Ministry of Education and Research) within \\it GeoTechnologien a new forward looking seismic imaging technique is developed to e.g. determine weak and water bearing zones ahead of the constructions. Our approach is based on the excitation and registration of \\it tunnel surface waves. These waves are excited at the tunnel face behind the cutter head of a tunnel boring machine and travel into drilling direction. Arriving at the front face they generate body waves (mainly S-waves) propagating further ahead. Reflected S-waves are back- converted into tunnel surface waves. For a theoretical description of the conversion process and for finding optimal acquisition geometries it is of importance to study the propagation characteristics of tunnel surface waves. 3D seismic finite difference modeling and analytic solutions of the wave equation in cylindric coordinates revealed that at higher frequencies, i.e. if the tunnel diameter is significantly larger than the wavelength of S-waves, these surface waves can be regarded as Rayleigh-waves circulating the tunnel. For smaller frequencies, i.e. when the S-wavelength approaches the tunnel diameter, the propagation characteristics of these surface waves are then similar to S- waves. Field measurements performed by the GeoForschungsZentrum Potsdam, Germany at the Gotthard Base Tunnel (Switzerland) show both effects, i.e. the propagation of Rayleigh- and body-wave like waves along the tunnel. To enhance our understanding of the excitation and propagation characteristics of tunnel surface waves the transition of Rayleigh to tube-waves waves is investigated both analytically and by numerical simulations.

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

    NASA Technical Reports Server (NTRS)

    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.

  13. Some Caves in tunnels in Dinaric karst of Croatia

    NASA Astrophysics Data System (ADS)

    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

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

    USGS Publications Warehouse

    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

  15. Water tunnel experiments on span-wise variation of laminar separation bubbles for swept and unswept wings using particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Gilbert, Jordan

    An inverted airfoil mounted above a flat plate was used to create laminar separation bubbles on a flat plate in water tunnel experiments at low Reynolds numbers. Boundary layer suction ensured that the flow remained attached to the wing. Two-dimensional PIV measurements were used to qualitatively and quantitatively characterize the spanwise bubble variation on an unswept wing and on the same wing featuring a 22 degree sweep. The separation bubbles were recorded at varied span-wise locations in a 31.5 cm wide region of the flow. The limitations of this measurement region were dictated by the focal length of the laser optic used for PIV measurements. The straight wing exhibited approximately uniform time averaged separation positions across the span of the wing. The reattachment locations varied only slightly which was expected due to the transition to turbulent flow before reattachment. A form of bubble "breathing" was observed in the laminar separation bubbles on the straight wing and is believed to have affected the mean reattachment locations for two data points recorded. The shedding frequencies on the straight wing were slightly higher than those obtained from CFD simulations. The swept wing planform showed significantly more variation in the mean separation and reattachment locations with respect to the leading edge of the wing. There is a general trend of the separation locations moving upstream in the direction of the aft leading edge. The reattachment points are shown to move downstream as the separation points move upstream relative to the leading edge and visa versa, displaying an inverse relationship between the two. The bubble lengths were found to be slightly longer on the swept wing compared to the straight wing usually by about 10%. The shedding frequencies on the swept wing were found to be lower than the straight wing. The quality of flow in the water tunnel may have degraded over time, showing signs of increased free stream turbulence. After data

  16. Quantum electron tunneling in respiratory complex I.

    PubMed

    Hayashi, Tomoyuki; Stuchebrukhov, Alexei A

    2011-05-12

    We have simulated the atomistic details of electronic wiring of all Fe/S clusters in complex I, a key enzyme in the respiratory electron transport chain. The tunneling current theory of many-electron systems is applied to the broken-symmetry (BS) states of the protein at the ZINDO level. While the one-electron tunneling approximation is found to hold in electron tunneling between the antiferromagnetic binuclear and tetranuclear Fe/S clusters without major orbital or spin rearrangement of the core electrons, induced polarization of the core electrons contributes significantly to decrease the electron transfer rates to 19-56 %. Calculated tunneling energy is about 3 eV higher than Fermi level in the band gap of the protein, which supports that the mechanism of electron transfer is quantum mechanical tunneling, as in the rest of the electron transport chain. Resulting electron tunneling pathways consist of up to three key contributing protein residues between neighboring Fe/S clusters. A signature of the wave properties of electrons is observed as distinct quantum interferences when multiple tunneling pathways exist. In N6a-N6b, electron tunnels along different pathways depending on the involved BS states, suggesting possible fluctuations of the tunneling pathways driven by the local protein environment. The calculated distance dependence of the electron transfer rates with internal water molecules included is in good agreement with a reported phenomenological relation.

  17. PUREX Storage Tunnels dangerous waste permit application

    SciTech Connect

    Not Available

    1991-12-01

    The PUREX Storage Tunnels are a mixed waste storage unit consisting of two underground railroad tunnels: Tunnel Number 1 designated 218-E-14 and Tunnel Number 2 designated 218-E-15. The two tunnels are connected by rail to the PUREX Plant and combine to provide storage space for 48 railroad cars (railcars). The PUREX Storage Tunnels provide a long-term storage location for equipment removed from the PUREX Plant. Transfers into the PUREX Storage Tunnels are made on an as-needed basis. Radioactively contaminated equipment is loaded on railcars and remotely transferred by rail into the PUREX Storage Tunnels. Railcars act as both a transport means and a storage platform for equipment placed into the tunnels. This report consists of part A and part B. Part A reports on amounts and locations of the mixed water. Part B permit application consists of the following: Facility Description and General Provisions; Waste Characteristics; Process Information; Groundwater Monitoring; Procedures to Prevent Hazards; Contingency Plan; Personnel Training; Exposure Information Report.

  18. Effectiveness of water spray mitigation systems for accidental releases of hydrogen fluoride. Volume 9. Wind tunnel modeling of fire monitors for HF vapor cloud mitigation, volume 1. Final report

    SciTech Connect

    Petersen, R.L.; Ratcliff, M.A.; Heskestad, G.; Parce, D.K.

    1992-05-01

    The hazards of hydrogen fluoride (HF) have long been recognized. Standard operating practices have been aimed at on minimizing the possibility of a release and mitigating the effects if a release should occur. These practices are continually monitored and improved to maximize safety protection based on the available technical data. The recent program targeted further improvements based on new technical data. The volume presents the results of wind tunnel simulations of water monitors and a surrogate gas for HF to quantify the effect of water spray/HF release configuration variables on the performance of multiple water monitors.

  19. Cryogenic wind tunnels. II

    NASA Technical Reports Server (NTRS)

    Kilgore, Robert A.

    1987-01-01

    The application of the cryogenic concept to various types of tunnels including Ludwieg tube tunnel, Evans clean tunnel, blowdown, induced-flow, and continuous-flow fan-driven tunnels is discussed. Benefits related to construction and operating costs are covered, along with benefits related to new testing capabilities. It is noted that cooling the test gas to very low temperatures increases Reynolds number by more than a factor of seven. From the energy standpoint, ambient-temperature fan-driven closed-return tunnels are considered to be the most efficient type of tunnel, while a large reduction in the required tunnel stagnation pressure can be achieved through cryogenic operation. Operating envelopes for three modes of operation for a cryogenic transonic pressure tunnel with a 2.5 by 2.5 test section are outlined. A computer program for calculating flow parameters and power requirements for wind tunnels with operating temperatures from saturation to above ambient is highlighted.

  20. Flow visualization study of spanwise blowing applied to the F-4 fighter aircraft configuration. [water tunnel test using a 1/48-scale model

    NASA Technical Reports Server (NTRS)

    Lorincz, D. J.

    1980-01-01

    Water tunnel studies were performed to define the changes that occur in vortex flow fields above the wing due to spanwise blowing over the inboard and outboard wing panels and over the trailing-edge flaps. Flow visualization photographs were obtained for angles of attack up to 30 deg and sideslip angles up to 10 deg. The sensitivity of the vortex flows to changes in flap deflection angle, nozzle position, and jet momentum coefficient was determined. Deflection of the leading edge flap delayed flow separation and the formation of the wing vortex to higher angles of attack. Spanwise blowing delayed the breakdown of the wing vortex to farther outboard and to higher angles of attack. Spanwise blowing over the trailing edge flap entrained flow downward, producing a lift increase over a wide range of angles of attack. The sweep angle of the windward wing was effectively reduced in sideslip. This decreased the stability of the wing vortex, and it burst farther inboard. Reduced wing sweep required a higher blowing rate to maintain a stable vortex. A vortex could be stabilized on the outboard wing panel when an outboard blowing nozzle was used. Blowing from both an inboard and an outboard nozzle was found to have a favorable interaction.

  1. Simulation of ground-water flow, surface-water flow, and a deep sewer tunnel system in the Menomonee Valley, Milwaukee, Wisconsin

    USGS Publications Warehouse

    Dunning, C.P.; Feinstein, D.T.; Hunt, R.J.; Krohelski, J.T.

    2004-01-01

    Numerical models were constructed for simulation of ground-water flow in the Menomonee Valley Brownfield, in Milwaukee, Wisconsin. An understanding of ground-water flow is necessary to develop an efficient program to sample ground water for contaminants. Models were constructed in a stepwise fashion, beginning with a regional, single-layer, analytic-element model (GFLOW code) that provided boundary conditions for a local, eight layer, finite-difference model (MODFLOW code) centered on the Menomonee Valley Brownfield. The primary source of ground water to the models is recharge over the model domains; primary sinks for ground water within the models are surface-water features and the Milwaukee Metropolitan Sewerage District Inline Storage System (ISS). Calibration targets were hydraulic heads, surface-water fluxes, vertical gradients, and ground-water infiltration to the ISS. Simulation of ground-water flow by use of the MODFLOW model indicates that about 73 percent of recharge within the MODFLOW domain circulates to the ISS and 27 percent discharges to gaining surface-water bodies. In addition, infiltration to the ISS comes from the following sources: 36 percent from recharge within the model domain, 45 percent from lateral flow into the domain, 15 percent from Lake Michigan, and 4 percent from other surface-water bodies. Particle tracking reveals that the median traveltime from the recharge point to surface-water features is 8 years; the median time to the ISS is 255 years. The traveltimes to the ISS are least over the northern part of the valley, where dolomite is near the land surface. The distribution of traveltimes in the MODFLOW simulation is greatly influenced by the effective porosity values assigned to the various lithologies.

  2. 4. 'Ring Stones & Tunnel Sections, Tunnel #33,' Southern Pacific ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. 'Ring Stones & Tunnel Sections, Tunnel #33,' Southern Pacific Standard Double-Track Tunnel, ca. 1913. Compare to photos in documentation sets for Tunnel 18 (HAER No. CA-197), Tunnel 34 (HAER No. CA-206), and Tunnel 1 (HAER No. CA-207). - Central Pacific Transcontinental Railroad, Sacramento to Nevada state line, Sacramento, Sacramento County, CA

  3. 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

    NASA Astrophysics Data System (ADS)

    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 (<10 m/year), this process is associated with a very large Li isotope fractionation factor (ε ≈ -50‰). Moreover, our simulations demonstrate that for simple

  4. Carpal tunnel repair - slideshow

    MedlinePlus

    ... page: //medlineplus.gov/ency/presentations/100078.htm Carpal tunnel repair - series—Normal anatomy To use the sharing ... in the wrist and the wrist bones (carpal tunnel). Review Date 5/9/2015 Updated by: C. ...

  5. Variable Density Tunnel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Variable Density Tunnel in operation. Man at far right is probably Harold J. 'Cannonball' Tuner, longtime safety officer, who started with Curtiss in the teens. This view of the Variable Density Tunnel clearly shows the layout of the Tunnel's surroundings, as well as the plumbing and power needs of the this innovative research tool.

  6. Metabolic power of European starlings Sturnus vulgaris during flight in a wind tunnel, estimated from heat transfer modelling, doubly labelled water and mask respirometry.

    PubMed

    Ward, S; Möller, U; Rayner, J M V; Jackson, D M; Nachtigall, W; Speakman, J R

    2004-11-01

    It is technically demanding to measure the energetic cost of animal flight. Each of the previously available techniques has some disadvantage as well advantages. We compared measurements of the energetic cost of flight in a wind tunnel by four European starlings Sturnus vulgaris made using three independent techniques: heat transfer modelling, doubly labelled water (DLW) and mask respirometry. We based our heat transfer model on thermal images of the surface temperature of the birds and air flow past the body and wings calculated from wing beat kinematics. Metabolic power was not sensitive to uncertainty in the value of efficiency when estimated from heat transfer modelling. A change in the assumed value of whole animal efficiency from 0.19 to 0.07 (the range of estimates in previous studies) only altered metabolic power predicted from heat transfer modelling by 13%. The same change in the assumed value of efficiency would cause a 2.7-fold change in metabolic power if it were predicted from mechanical power. Metabolic power did not differ significantly between measurements made using the three techniques when we assumed an efficiency in the range 0.11-0.19, although the DLW results appeared to form a U-shaped power-speed curve while the heat transfer model and respirometry results increased linearly with speed. This is the first time that techniques for determining metabolic power have been compared using data from the same birds flying under the same conditions. Our data provide reassurance that all the techniques produce similar results and suggest that heat transfer modelling may be a useful method for estimating metabolic rate.

  7. Tunnel allows landfall approach for Troll pipeline

    SciTech Connect

    Hove, F.; Kuhlmann, H.

    1995-12-04

    A 4-km landfall tunnel was constructed to provide an approach to the rugged Norwegian coast for 36 and 40-in. offshore pipelines in Troll Phase 1 development. The tunnel terminates in 165 m of water with three vertical shaft connections to the seabed. Construction consisted of two main elements: 180 metric ton tie-in spools installed between the offshore pipelines and the piercing shafts, and prefabricated 450 metric ton riser bundles installed in the vertical tunnel piercing shafts. The paper describes the seabed route, the tie-in design approach, and construction on the seabed and underground. First gas is scheduled to flow in April, 1996.

  8. Feasibility assessment of a tunnel-ventilated, water-padded barn on alleviation of heat stress for lactating Holstein cows in a humid area.

    PubMed

    Shiao, T F; Chen, J C; Yang, D W; Lee, S N; Lee, C F; Cheng, W T K

    2011-11-01

    The use of evaporative cooling for mitigating heat stress in lactating cows in humid areas is controversial. In Taiwan, Holstein cow performance is significantly restricted by hot and humid weather. This study investigated the efficacy of using a tunnel-ventilated, water-padded freestall (TP) barn for reducing heat stress in lactating cows. From August to October 2006, 36 cows allocated in a 3×3 Latin square were raised in 3 barn cooling treatments: a conventional freestall barn with fans and sprinklers in the feed line (Fan+SP, control), a TP barn, and a TP barn with sprinkler cooling (TP+SP). Daytime air speeds in the 3 barns were 1.23, 2.38, and 2.06 m/s, respectively. Both TP barns were more efficient than the control in reducing the daytime temperature and temperature-humidity index. The barn temperature was <26°C for an extra 4.2h per day, but the relative humidity was >96% in both TP barns. Cows in both TP barns had higher respiration rates and skin temperatures at 0300 h than cows in the Fan+SP barn. The TP environment increased the cows' serum cholesterol level and the activities of alkaline phosphatase and alanine aminotransferase, but blood partial pressure of CO(2) was not affected. Vaginal temperature was persistently high in cows in the TP barn; in the 2 SP barns, it decreased 0.4 to 0.6°C following sprinkling and milking. The intake activity and rumen digestion of cows raised in the 3 environments were similar. Cows in both TP barns ingested more dry matter. Cows in the TP+SP barn tended to produce more milk than those in the Fan+SP barn (25.4 vs. 24.7 kg). Although heat stress was not completely alleviated in these 3 barns, the TP+SP treatment resolved the negative effect of a previous TP barn built in 2004 on intake and milk yield by increasing air speed and using sprinkler cooling. Thus, it is expected that TP+SP barns will be beneficial in regions with high humidity. Adequate air speed and sprinkler cooling are likely to be key factors for

  9. The cryogenic wind tunnel

    NASA Technical Reports Server (NTRS)

    Kilgore, R. A.

    1976-01-01

    Based on theoretical studies and experience with a low speed cryogenic tunnel and with a 1/3-meter transonic cryogenic tunnel, the cryogenic wind tunnel concept was shown to offer many advantages with respect to the attainment of full scale Reynolds number at reasonable levels of dynamic pressure in a ground based facility. The unique modes of operation available in a pressurized cryogenic tunnel make possible for the first time the separation of Mach number, Reynolds number, and aeroelastic effects. By reducing the drive-power requirements to a level where a conventional fan drive system may be used, the cryogenic concept makes possible a tunnel with high productivity and run times sufficiently long to allow for all types of tests at reduced capital costs and, for equal amounts of testing, reduced total energy consumption in comparison with other tunnel concepts.

  10. Simulator of Road Tunnel

    NASA Astrophysics Data System (ADS)

    Danišovič, Peter; Schlosser, František; Šrámek, Juraj; Rázga, Martin

    2015-05-01

    A Tunnel Traffic & Operation Simulator is a device of the Centre of Transport Research at the University of Žilina. The Simulator allows managing technological equipment of virtual two-tube highway tunnel, which is interconnected with simulation of vehicle traffic in tunnel. Changes of the traffic-operation states and other equipment are reflecting at the simulated traffic, as well as simulations of various emergency events in traffic initiate changes in tunnel detecting and measuring devices. It is thus possible to simulate emergency states, which can be affected by various faults of technology as well as by climatic conditions. The solutions can be found in irreplaceable experiences of Slovak road tunnel operators, changes of trafficoperation states, visualizations of operator technological display screens, technological devices labelling in order to increase operational safety of road tunnels.

  11. Pipetron Tunnel Construction Issues

    SciTech Connect

    Friant, James E.; Bauer, Robert A.; Gross, David L.; May, Michael; Lach, Joseph

    1997-01-01

    This report examines issues involved in the civil construction aspects of the tunneling that could be done in the region of Fermilab to support the Pipetron along, moderately deep, tunnel loop. Cost, technical and political aspects of tunneling are addressed in this preliminary guide for further study. At Snowmass 96, in a series of informal, but comprehensive discussions, several guidelines were developed to frame this report.

  12. Charge Islands Through Tunneling

    NASA Technical Reports Server (NTRS)

    Robinson, Daryl C.

    2002-01-01

    It has been recently reported that the electrical charge in a semiconductive carbon nanotube is not evenly distributed, but rather it is divided into charge "islands." This paper links the aforementioned phenomenon to tunneling and provides further insight into the higher rate of tunneling processes, which makes tunneling devices attractive. This paper also provides a basis for calculating the charge profile over the length of the tube so that nanoscale devices' conductive properties may be fully exploited.

  13. Tunnel closure calculations

    SciTech Connect

    Moran, B.; Attia, A.

    1995-07-01

    When a deeply penetrating munition explodes above the roof of a tunnel, the amount of rubble that falls inside the tunnel is primarily a function of three parameters: first the cube-root scaled distance from the center of the explosive to the roof of the tunnel. Second the material properties of the rock around the tunnel, and in particular the shear strength of that rock, its RQD (Rock Quality Designator), and the extent and orientation of joints. And third the ratio of the tunnel diameter to the standoff distance (distance between the center of explosive and the tunnel roof). The authors have used CALE, a well-established 2-D hydrodynamic computer code, to calculate the amount of rubble that falls inside a tunnel as a function of standoff distance for two different tunnel diameters. In particular they calculated three of the tunnel collapse experiments conducted in an iron ore mine near Kirkeness, Norway in the summer of 1994. The failure model that they used in their calculations combines an equivalent plastic strain criterion with a maximum tensile strength criterion and can be calibrated for different rocks using cratering data as well as laboratory experiments. These calculations are intended to test and improve the understanding of both the Norway Experiments and the ACE (Array of conventional Explosive) phenomenology.

  14. TBM tunnel friction values for the Grizzly Powerhouse Project

    SciTech Connect

    Stutsman, R.D.; Rothfuss, B.D.

    1995-12-31

    Tunnel boring machine (TBM) driven water conveyance tunnels are becoming increasingly more common. Despite advances in tunnel engineering and construction technology, hydraulic performance data for TBM driven tunnels remains relatively unavailable. At the Grizzly Powerhouse Project, the TBM driven water conveyance tunnel was designed using friction coefficients developed from a previous PG&E project. A range of coefficients were selected to bound the possible hydraulic performance variations of the water conveyance system. These friction coefficients, along with the water conveyance systems characteristics, and expected turbine characteristics, were used in a hydraulic transient analysis to determine the expected system pressure fluctuations, and surge chamber performance. During startup test data, these performance characteristics were measured to allow comparison to the original design assumptions. During construction of the tunnel, plaster casts were made of the actual excavated tunnel unlined and fiber reinforced shotcrete lined surfaces. These castings were used to measure absolute roughness of the surfaces so that a friction coefficient could be developed using the Moody diagram and compare them against the design values. This paper compares the assumed frictional coefficient with computed coefficients from headlosses measured during startup testing, and plaster cast measurement calculations. In addition, a comparison of coefficients will be presented for an other TBM driven water conveyance tunnel constructed in the 1980`s.

  15. The carpal tunnel.

    PubMed

    Ellis, Harold

    2009-12-01

    The carpal bones are deeply convex anteriorly. This bony gutter is converted by the flexor retinaculum into a tube - the carpal tunnel, which conveys the median nerve, together with the long flexor tendons of the fingers and thumb, into the hand. It is of special interest to the surgeon because it is the site of a common nerve entrapment, the carpal tunnel syndrome.

  16. Shotcrete in tunnel design

    SciTech Connect

    Golser, J.; Galler, R.; Schubert, P.; Rabensteiner, K.

    1995-12-31

    Shotcrete is an important structural element for tunnel support. Green shotcrete is exposed to compression strain rates and tunnel design requires a realistic material law for shotcrete. A modified rate of flow method simulates shotcrete behavior very well and can be incorporated in Finite Element calculations.

  17. Proceedings of the 10th rapid excavation and tunneling conference

    SciTech Connect

    Wightman, W.D.

    1991-01-01

    The 1991 Rapid Excavation and Tunneling Conference, the tenth gathering of the industry, selected Seattle, Washington, for the presentation. The purpose of the conference is to share and promulgate advances in the state-of-the-art of underground construction and the innovative solutions to the inherent problems associated with this work. A truly international event, one-third of the presentations are from foreign countries. Mammoth projects highlighted include: the Channel Tunnels between England and France and the Great Belt Tunnels in Denmark, the Superconducting Super Collider Project, the Massachusetts Water Resources Authority Boston Harbor Project, and the Passaic River Basin Tunnel.

  18. The Stability Tunnel

    NASA Technical Reports Server (NTRS)

    1943-01-01

    Engineers operate the controls of the Stability Tunnel: Plans for a new tunnel to study stability problems began in the late thirties. The Stability Tunnel was authorized in 1939 and began operations in June 1941. The installation was completed in December that year with the completion of a new 10,000 Horsepower Diesel-electric generating plant. It was a single return, closed jet tunnel with a 6-foot square test section. The tunnel was disassembled and shipped to Virginia Polytechnic Institute and State University in 1958. The tunnel had two separate test sections: one for curved flow, the other for rolling flow. 'The facility...simulates the motion of the aircraft in curved or rolling flight. This is done by actually curving or rolling the airstream as it passes over the model and at the same time providing the proper velocity distribution.' (From AIAA-80-0309) >From Alan Pope, Wind-Tunnel Testing: 'The only tunnel directly designed for dynamic stability work is located at the Langley Field branch of the NACA. Its most vital feature is its ability to subject the models to curving air streams that simulate those actually encountered when an airplane rolls, pitches, or yaws. the rotating airstream for simulating roll is produced by a motor-driven paddle just ahead of the test section. Curved air of properly varying velocity for simulating pitch and yaw is produced by a combination of a curved test section and velocity screens. The proper use of this apparatus makes possible the determination of the stability derivatives.' Published in F.H. Lutze, 'Experimental Determination of Pure Rotary Stability Derivatives using a Curved and Rolling Flow Wind Tunnel,' AIAA-80-0309, AIAA 18th Aerospace Sciences Meeting, Pasadena, CA, January 14-16, 1980; Alan Pope, Wind-Tunnel Testing (New York: John Wiley & Sons, 1947).

  19. Radiometric dating of the Siloam Tunnel, Jerusalem.

    PubMed

    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.

  20. Ultrafast scanning tunneling microscopy

    SciTech Connect

    Botkin, D.A. |

    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.

  1. [Anterior tarsal tunnel syndrome].

    PubMed

    Miliam, Palle B; Basse, Peter N

    2009-03-30

    Anterior tarsal tunnel syndrome is a rare entrapment neuropathy of the deep peroneal nerve beneath the extensor retinaculum of the ankle. It may be rare because it is underrecognized clinically.We present a case regarding a 29-year-old man, drummer, who for one and a half year experienced clinical symptoms of anterior tarsal tunnel syndrome. A surgical decompression of the anterior tarsal tunnel was performed, and at the check three months later the symptoms where gone. One year after, there were still no symptoms.

  2. Carpal tunnel release

    MedlinePlus

    ... you are taking. This includes medicines, supplements, or herbs you bought without a prescription. You may be ... gov/pubmed/23026458 . Zhao M, Burke DT. Median neuropathy (carpal tunnel syndrome). In: Frontera WR, Silver JK, ...

  3. Endoscopic cubital tunnel release.

    PubMed

    Cobb, Tyson K

    2010-10-01

    A minimally invasive endoscopic approach has been successfully applied to surgical treatment of cubital tunnel syndrome. This procedure allows for smaller incisions with faster recovery time. This article details relevant surgical anatomy, indications, contraindications, surgical technique, complications, and postoperative management.

  4. Inelastic electron tunneling spectroscopy

    NASA Technical Reports Server (NTRS)

    Khanna, S. K.; Lambe, J.

    1983-01-01

    Inelastic electron tunneling spectroscopy is a useful technique for the study of vibrational modes of molecules adsorbed on the surface of oxide layers in a metal-insulator-metal tunnel junction. The technique involves studying the effects of adsorbed molecules on the tunneling spectrum of such junctions. The data give useful information about the structure, bonding, and orientation of adsorbed molecules. One of the major advantages of inelastic electron tunneling spectroscopy is its sensitivity. It is capable of detecting on the order of 10 to the 10th molecules (a fraction of a monolayer) on a 1 sq mm junction. It has been successfully used in studies of catalysis, biology, trace impurity detection, and electronic excitations. Because of its high sensitivity, this technique shows great promise in the area of solid-state electronic chemical sensing.

  5. World's Largest Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1987-01-01

    NASA's National Full Scale Aerodynamics Complex, which houses two of the world's largest wind tunnels and has been used for testing experimental aircraft since 1944, is presented. This video highlights the structure and instrumentation of the 40 x 80 foot and 80 x 120 foot wind tunnels and documents their use in testing full scale aircraft, NASA's Space Shuttle and the XV-15 Tiltrotor aircraft.

  6. Electron tunnel sensor technology

    NASA Technical Reports Server (NTRS)

    Kenny, T. W.; Waltman, S. B.; Reynolds, J. K.; Kaiser, W. J.

    1991-01-01

    Researchers designed and constructed a novel electron tunnel sensor which takes advantage of the mechanical properties of micro-machined silicon. For the first time, electrostatic forces are used to control the tunnel electrode separation, thereby avoiding the thermal drift and noise problems associated with piezoelectric actuators. The entire structure is composed of micro-machined silicon single crystals, including a folded cantilever spring and a tip. The application of this sensor to the development of a sensitive accelerometer is described.

  7. Full Scale Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Construction of motor fairing for the fan motors of the Full-Scale Tunnel (FST). The motors and their supporting structures were enclosed in aerodynamically smooth fairings to minimize resistance to the air flow. Close examination of this photograph reveals the complicated nature of constructing a wind tunnel. This motor fairing, like almost every other structure in the FST, represents a one-of-a-kind installation.

  8. Novel tunnelling barriers for spin tunnelling junctions

    NASA Astrophysics Data System (ADS)

    Sharma, Manish

    A tunnel junction consists of two metal electrodes separated by an insulating barrier thin enough for electrons to tunnel across. With ferromagnetic electrodes, a spin-dependent tunnelling (SDT) effect, electrons of one spin tunnelling preferentially over those of the other, is observed. When the electrodes are switched from a parallel to an anti-parallel alignment, the tunnelling current changes and gives rise to tunnelling magnetoresistance (TMR). Since 1995, interest in SDT junctions has increased as TMR in excess of 15% has been achieved, making viable their use in non-volatile memory and magnetic sensors applications. In this work, two key issues of SDT junctions are addressed: spin polarization of the electrode and the tunnel barrier. Spin polarization, a measure of electron states of up and down spins, is widely believed to be an intrinsic property of the electrode. In junctions with barriers formed by plasma oxidation of composite Ta/Al films, the surprising effect of the resistance being lower with the electrodes aligned antiparallel was observed. Junctions with Ta/Al barriers and those with Al/Ta barriers behave opposite to each other and exhibit an inversion only when the Ta side of the barrier is biased positive. This demonstrates the spin polarization is also influenced by the barrier material. Half-metallic materials such as magnetite (Fe3O4) have a gap in one of the spins' states at the fermi level, thus having a theoretical spin polarization of 100%. In this work, an ultrathin Fe3O 4 layer was added between the Al2O3 barrier and the NiFe electrode. The TMR increased sharply from 4% to 16% for thicknesses less than 0.5nm. As the tunnel barrier must be thinner than 2nm, choice of the barrier material becomes critical. Presently, Al2O3 is the best known barrier. In looking for alternative materials, AlN and AlON were formed by plasma nitridation and oxy-nitridation of deposited Al films. TMR results of up to 18% and resistance-area products down to 3

  9. The Beginner's Guide to Wind Tunnels with TunnelSim and TunnelSys

    NASA Technical Reports Server (NTRS)

    Benson, Thomas J.; Galica, Carol A.; Vila, Anthony J.

    2010-01-01

    The Beginner's Guide to Wind Tunnels is a Web-based, on-line textbook that explains and demonstrates the history, physics, and mathematics involved with wind tunnels and wind tunnel testing. The Web site contains several interactive computer programs to demonstrate scientific principles. TunnelSim is an interactive, educational computer program that demonstrates basic wind tunnel design and operation. TunnelSim is a Java (Sun Microsystems Inc.) applet that solves the continuity and Bernoulli equations to determine the velocity and pressure throughout a tunnel design. TunnelSys is a group of Java applications that mimic wind tunnel testing techniques. Using TunnelSys, a team of students designs, tests, and post-processes the data for a virtual, low speed, and aircraft wing.

  10. Formation of the prebiotic molecule NH2CHO on astronomical amorphous solid water surfaces: accurate tunneling rate calculations† †Electronic supplementary information (ESI) available: Geometric details, lists of calculated rate constants. See DOI: 10.1039/c6cp05727f Click here for additional data file.

    PubMed Central

    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 ∼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 → NH2CO 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 barrier affect the tunneling rate in practice. Strong kinetic isotope effects were observed by comparing to rate constants of D + HNCO → NHDCO. At 103 K we found a KIE of 231 on the surface and 146 in the gas phase. Furthermore, we investigated the gas-phase reaction NH2 + H2CO → NH2CHO + H and found it unlikely to occur at cryogenic temperatures. The data of our tunneling rate constants are expected to significantly influence astrochemical models. PMID:27731439

  11. Single Electron Tunneling

    SciTech Connect

    Ruggiero, Steven T.

    2005-07-25

    Financial support for this project has led to advances in the science of single-electron phenomena. Our group reported the first observation of the so-called ''Coulomb Staircase'', which was produced by tunneling into ultra-small metal particles. This work showed well-defined tunneling voltage steps of width e/C and height e/RC, demonstrating tunneling quantized on the single-electron level. This work was published in a now well-cited Physical Review Letter. Single-electron physics is now a major sub-field of condensed-matter physics, and fundamental work in the area continues to be conducted by tunneling in ultra-small metal particles. In addition, there are now single-electron transistors that add a controlling gate to modulate the charge on ultra-small photolithographically defined capacitive elements. Single-electron transistors are now at the heart of at least one experimental quantum-computer element, and single-electron transistor pumps may soon be used to define fundamental quantities such as the farad (capacitance) and the ampere (current). Novel computer technology based on single-electron quantum dots is also being developed. In related work, our group played the leading role in the explanation of experimental results observed during the initial phases of tunneling experiments with the high-temperature superconductors. When so-called ''multiple-gap'' tunneling was reported, the phenomenon was correctly identified by our group as single-electron tunneling in small grains in the material. The main focus throughout this project has been to explore single electron phenomena both in traditional tunneling formats of the type metal/insulator/particles/insulator/metal and using scanning tunneling microscopy to probe few-particle systems. This has been done under varying conditions of temperature, applied magnetic field, and with different materials systems. These have included metals, semi-metals, and superconductors. Amongst a number of results, we have

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Carpal Tunnel Syndrome

    PubMed Central

    Zimmerman, Gregory R.

    1994-01-01

    Carpal tunnel syndrome is a neuropathy resulting from compression of the median nerve as it passes through a narrow tunnel in the wrist on its way to the hand. The lack of precise objective and clinical tests, along with symptoms that are synonymous with other syndromes in the upper extremity, cause carpal tunnel syndrome to appear to be a rare entity in athletics. However, it should not be ruled out as a possible etiology of upper extremity paralysis in the athlete. More typically, carpal tunnel syndrome is the most common peripheral entrapment neuropathy encountered in industry. Treatment may include rest and/or splinting of the involved wrist, ice application, galvanic stimulation, or iontophoresis to reduce inflammation, and then transition to heat modalities and therapeutic exercises for developing flexibility, strength, and endurance. In addition, an ergonomic assessment should be conducted, resulting in modifications to accommodate the carpal tunnel syndrome patient. ImagesFig 3.Fig 4.Fig 5.Fig 6.Fig 7. PMID:16558255

  14. Condensate Mixtures and Tunneling

    SciTech Connect

    Timmermans, E.

    1998-09-14

    The experimental study of condensate mixtures is a particularly exciting application of the recently developed atomic-trap Bose-Einstein condensate (BEC) technology: such multiple condensates represent the first laboratory systems of distinguishable boson superfluid mixtures. In addition, as the authors point out in this paper, the possibility of inter-condensate tunneling greatly enhances the richness of the condensate mixture physics. Not only does tunneling give rise to the oscillating particle currents between condensates of different chemical potentials, such as those studied extensively in the condensed matter Josephson junction experiments, it also affects the near-equilibrium dynamics and stability of the condensate mixtures. In particular, the stabilizing influence of tunneling with respect to spatial separation (phase separation) could be of considerable practical importance to the atomic trap systems. Furthermore, the creation of mixtures of atomic and molecular condensates could introduce a novel type of tunneling process, involving the conversion of a pair of atomic condensate bosons into a single molecular condensate boson. The static description of condensate mixtures with such type of pair tunneling suggests the possibility of observing dilute condensates with the liquid-like property of a self-determined density.

  15. The geometry of the ribosomal polypeptide exit tunnel.

    PubMed

    Voss, N R; Gerstein, M; Steitz, T A; Moore, P B

    2006-07-21

    The geometry of the polypeptide exit tunnel has been determined using the crystal structure of the large ribosomal subunit from Haloarcula marismortui. The tunnel is a component of a much larger, interconnected system of channels accessible to solvent that permeates the subunit and is connected to the exterior at many points. Since water and other small molecules can diffuse into and out of the tunnel along many different trajectories, the large subunit cannot be part of the seal that keeps ions from passing through the ribosome-translocon complex. The structure referred to as the tunnel is the only passage in the solvent channel system that is both large enough to accommodate nascent peptides, and that traverses the particle. For objects of that size, it is effectively an unbranched tube connecting the peptidyl transferase center of the large subunit and the site where nascent peptides emerge. At no point is the tunnel big enough to accommodate folded polypeptides larger than alpha-helices.

  16. Femtosecond scanning tunneling microscope

    SciTech Connect

    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.

  17. Uncooled tunneling infrared sensor

    NASA Technical Reports Server (NTRS)

    Kenny, Thomas W. (Inventor); Kaiser, William J. (Inventor); Podosek, Judith A. (Inventor); Vote, Erika C. (Inventor); Muller, Richard E. (Inventor); Maker, Paul D. (Inventor)

    1995-01-01

    An uncooled infrared tunneling sensor in which the only moving part is a diaphragm which is deflected into contact with a micromachined silicon tip electrode prepared by a novel lithographic process. Similarly prepared deflection electrodes employ electrostatic force to control the deflection of a silicon nitride, flat diaphragm membrane. The diaphragm exhibits a high resonant frequency which reduces the sensor's sensitivity to vibration. A high bandwidth feedback circuit controls the tunneling current by adjusting the deflection voltage to maintain a constant deflection of the membrane. The resulting infrared sensor can be miniaturized to pixel dimensions smaller than 100 .mu.m. An alternative embodiment is implemented using a corrugated membrane to permit large deflection without complicated clamping and high deflection voltages. The alternative embodiment also employs a pinhole aperture in a membrane to accommodate environmental temperature variation and a sealed chamber to eliminate environmental contamination of the tunneling electrodes and undesireable accoustic coupling to the sensor.

  18. View down tank tunnel (tunnel no. 2) showing pipes and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View down tank tunnel (tunnel no. 2) showing pipes and walkway of metal grating, side tunnel to tank 3 is on the left - U.S. Naval Base, Pearl Harbor, Diesel Purification Plant, North Road near Pierce Street, Pearl City, Honolulu County, HI

  19. Aorto-ventricular tunnel

    PubMed Central

    McKay, Roxane

    2007-01-01

    Aorto-ventricular tunnel is a congenital, extracardiac channel which connects the ascending aorta above the sinutubular junction to the cavity of the left, or (less commonly) right ventricle. The exact incidence is unknown, estimates ranging from 0.5% of fetal cardiac malformations to less than 0.1% of congenitally malformed hearts in clinico-pathological series. Approximately 130 cases have been reported in the literature, about twice as many cases in males as in females. Associated defects, usually involving the proximal coronary arteries, or the aortic or pulmonary valves, are present in nearly half the cases. Occasional patients present with an asymptomatic heart murmur and cardiac enlargement, but most suffer heart failure in the first year of life. The etiology of aorto-ventricular tunnel is uncertain. It appears to result from a combination of maldevelopment of the cushions which give rise to the pulmonary and aortic roots, and abnormal separation of these structures. Echocardiography is the diagnostic investigation of choice. Antenatal diagnosis by fetal echocardiography is reliable after 18 weeks gestation. Aorto-ventricular tunnel must be distinguished from other lesions which cause rapid run-off of blood from the aorta and produce cardiac failure. Optimal management of symptomatic aorto-ventricular tunnel consists of diagnosis by echocardiography, complimented with cardiac catheterization as needed to elucidate coronary arterial origins or associated defects, and prompt surgical repair. Observation of the exceedingly rare, asymptomatic patient with a small tunnel may be justified by occasional spontaneous closure. All patients require life-long follow-up for recurrence of the tunnel, aortic valve incompetence, left ventricular function, and aneurysmal enlargement of the ascending aorta. PMID:17922908

  20. Aorto-ventricular tunnel.

    PubMed

    McKay, Roxane

    2007-10-08

    Aorto-ventricular tunnel is a congenital, extracardiac channel which connects the ascending aorta above the sinutubular junction to the cavity of the left, or (less commonly) right ventricle. The exact incidence is unknown, estimates ranging from 0.5% of fetal cardiac malformations to less than 0.1% of congenitally malformed hearts in clinico-pathological series. Approximately 130 cases have been reported in the literature, about twice as many cases in males as in females. Associated defects, usually involving the proximal coronary arteries, or the aortic or pulmonary valves, are present in nearly half the cases. Occasional patients present with an asymptomatic heart murmur and cardiac enlargement, but most suffer heart failure in the first year of life. The etiology of aorto-ventricular tunnel is uncertain. It appears to result from a combination of maldevelopment of the cushions which give rise to the pulmonary and aortic roots, and abnormal separation of these structures. Echocardiography is the diagnostic investigation of choice. Antenatal diagnosis by fetal echocardiography is reliable after 18 weeks gestation. Aorto-ventricular tunnel must be distinguished from other lesions which cause rapid run-off of blood from the aorta and produce cardiac failure. Optimal management of symptomatic aorto-ventricular tunnel consists of diagnosis by echocardiography, complimented with cardiac catheterization as needed to elucidate coronary arterial origins or associated defects, and prompt surgical repair. Observation of the exceedingly rare, asymptomatic patient with a small tunnel may be justified by occasional spontaneous closure. All patients require life-long follow-up for recurrence of the tunnel, aortic valve incompetence, left ventricular function, and aneurysmal enlargement of the ascending aorta.

  1. Future tunnelling projects in Iceland

    SciTech Connect

    Jonsson, B. )

    1992-04-01

    More than 300 km of hydro tunnels and 80-90 km of road tunnels could be excavated in Iceland before the year 2050. In order to complete this task, an average of 6-7 km of tunnel per year would have to be driven. This volume of tunnelling is estimated to cost more than $US1 billion, which could be divided as follows: (a) about 100 km of 3.5-m-wide diversion hydro tunnels (unsupported), for a total of $90 million; (b) approx. 100 km of 5-m-wide hydro tunnels (supported), for a total of $210 million; (c) about 100 km of 7.6-m-wide hydro tunnels (supported), for a total of $380 million; and (d) approx. 85 km of road tunnels with 25 m[sup 2] cross-section, for a total of $435 million. 5 refs., 5 figs., 4 tabs.

  2. Carpal Tunnel Syndrome (For Kids)

    MedlinePlus

    ... Dictionary of Medical Words En Español What Other Kids Are Reading Taking Care of Your Ears Taking ... an X-ray Carpal Tunnel Syndrome KidsHealth > For Kids > Carpal Tunnel Syndrome Print A A A What's ...

  3. High-speed Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Ackeret, J

    1936-01-01

    Wind tunnel construction and design is discussed especially in relation to subsonic and supersonic speeds. Reynolds Numbers and the theory of compressible flows are also taken into consideration in designing new tunnels.

  4. Instrumentation in wind tunnels

    NASA Technical Reports Server (NTRS)

    Takashima, K.

    1986-01-01

    Requirements in designing instrumentation systems and measurements of various physical quantities in wind tunnels are surveyed. Emphasis is given to sensors used for measuring pressure, temperature, and angle, and the measurements of air turbulence and boundary layers. Instrumentation in wind tunnels require accuracy, fast response, diversity and operational simplicity. Measurements of force, pressure, attitude angle, free flow, pressure distribution, and temperature are illustrated by a table, and a block diagram. The LDV (laser Doppler velocimeter) method for measuring air turbulence and flow velocity and measurement of skin friction and flow fields using laser holograms are discussed. The future potential of these techniques is studied.

  5. Tunneling in axion monodromy

    NASA Astrophysics Data System (ADS)

    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.

  6. Scanning tunneling microscope nanoetching method

    DOEpatents

    Li, Yun-Zhong; Reifenberger, Ronald G.; Andres, Ronald P.

    1990-01-01

    A method is described for forming uniform nanometer sized depressions on the surface of a conducting substrate. A tunneling tip is used to apply tunneling current density sufficient to vaporize a localized area of the substrate surface. The resulting depressions or craters in the substrate surface can be formed in information encoding patterns readable with a scanning tunneling microscope.

  7. Carpal tunnel syndrome

    PubMed Central

    2014-01-01

    Introduction Carpal tunnel syndrome is a collection of clinical symptoms and signs caused by compression of the median nerve within the carpal tunnel. However, the severity of symptoms and signs does not often correlate well with the extent of nerve compression. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of drug treatments, non-drug treatments, and surgical treatments for carpal tunnel syndrome? We searched: Medline, Embase, The Cochrane Library, and other important databases up to October 2013 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 33 studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: carpal tunnel release surgery (open and endoscopic), diuretics, local corticosteroids injection, non-steroidal anti-inflammatory drugs (NSAIDs), therapeutic ultrasound, and wrist splints.

  8. Carpal tunnel syndrome

    PubMed Central

    2010-01-01

    Introduction Carpal tunnel syndrome is a neuropathy caused by compression of the median nerve within the carpal tunnel. However, the severity of symptoms and signs does not often correlate well with the extent of nerve damage. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of drug treatments, non-drug treatments, surgical treatments, and postoperative treatments for carpal tunnel syndrome? We searched: Medline, Embase, The Cochrane Library, and other important databases up to March 2009 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 53 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: acupuncture, carpal tunnel release surgery (open and endoscopic), diuretics, internal neurolysis, local and systemic corticosteroids, massage therapy, nerve and tendon gliding exercises, non-steroidal anti-inflammatory drugs (NSAIDs), pyridoxine, therapeutic ultrasound, and wrist splints. PMID:21718565

  9. Wind Tunnel Balances

    NASA Technical Reports Server (NTRS)

    Warner, Edward P; Norton, F H

    1920-01-01

    Report embodies a description of the balance designed and constructed for the use of the National Advisory Committee for Aeronautics at Langley Field, and also deals with the theory of sensitivity of balances and with the errors to which wind tunnel balances of various types are subject.

  10. Tunneling path toward spintronics

    NASA Astrophysics Data System (ADS)

    Miao, Guo-Xing; Münzenberg, Markus; Moodera, Jagadeesh S.

    2011-03-01

    The phenomenon of quantum tunneling, which was discovered almost a century ago, has led to many subsequent discoveries. One such discovery, spin polarized tunneling, was made 40 years ago by Robert Meservey and Paul Tedrow (Tedrow and Meservey 1971 Phys. Rev. Lett. 26 192), and it has resulted in many fundamental observations and opened up an entirely new field of study. Until the mid-1990s, this field developed at a steady, low rate, after which a huge increase in activity suddenly occurred as a result of the unraveling of successful spin tunneling between two ferromagnets. In the past 15 years, several thousands of papers related to spin polarized tunneling and transport have been published, making this topic one of the hottest areas in condensed matter physics from both fundamental science and applications viewpoints. Many review papers and book chapters have been written in the past decade on this subject. This paper is not exhaustive by any means; rather, the emphases are on recent progress, technological developments and informing the reader about the current direction in which this topic is moving.

  11. Tunnelling with wormhole creation

    SciTech Connect

    Ansoldi, S.; Tanaka, T.

    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.

  12. Full Scale Tunnel model

    NASA Technical Reports Server (NTRS)

    1929-01-01

    Interior view of Full-Scale Tunnel (FST) model. (Small human figures have been added for scale.) 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.

  13. Dry wind tunnel system

    NASA Technical Reports Server (NTRS)

    Chen, Ping-Chih (Inventor)

    2013-01-01

    This invention is a ground flutter testing system without a wind tunnel, called Dry Wind Tunnel (DWT) System. The DWT system consists of a Ground Vibration Test (GVT) hardware system, a multiple input multiple output (MIMO) force controller software, and a real-time unsteady aerodynamic force generation software, that is developed from an aerodynamic reduced order model (ROM). The ground flutter test using the DWT System operates on a real structural model, therefore no scaled-down structural model, which is required by the conventional wind tunnel flutter test, is involved. Furthermore, the impact of the structural nonlinearities on the aeroelastic stability can be included automatically. Moreover, the aeroservoelastic characteristics of the aircraft can be easily measured by simply including the flight control system in-the-loop. In addition, the unsteady aerodynamics generated computationally is interference-free from the wind tunnel walls. Finally, the DWT System can be conveniently and inexpensively carried out as a post GVT test with the same hardware, only with some possible rearrangement of the shakers and the inclusion of additional sensors.

  14. The Mystery Tunnel

    ERIC Educational Resources Information Center

    McCormack, Alan J.

    1974-01-01

    Describes a mystery tunnel, constructed by teachers, which provides a variety of non-visual, sensory experiences for children as they crawl through it. It is designed to help primary children develop basic abilities to use their own senses to better observe, discriminate among observations, and describe their own perceptions accurately. (JR)

  15. The Channel Tunnel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Channel Tunnel is a 50.5 km-long rail tunnel beneath the English Channel at the Straits of Dover. It connects Dover, Kent in England with Calais, northern France. The undersea section of the tunnel is unsurpassed in length in the world. A proposal for a Channel tunnel was first put forward by a French engineer in 1802. In 1881, a first attempt was made at boring a tunnel from the English side; the work was halted after 800 m. Again in 1922, English workers started boring a tunnel, and advanced 120 m before it too was halted for political reasons. The most recent attempt was begun in 1987, and the tunnel was officially opened in 1994. At completion it was estimated that the project cost around $18 billion. It has been operating at a significant loss since its opening, despite trips by over 7 million passengers per year on the Eurostar train, and over 3 million vehicles per year.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring

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

    PubMed

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

    2017-03-22

    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.

  17. Moisture Transport Through Sprayed Concrete Tunnel Linings

    NASA Astrophysics Data System (ADS)

    Holter, Karl Gunnar; Geving, Stig

    2016-01-01

    Waterproofing of permanent sprayed concrete tunnel linings with sprayed membranes in a continuous sandwich structure has been attempted since 2000 and has seen increased use in some countries. The main function of a sprayed membrane from a waterproofing perspective is to provide crack bridging and hence prevent flow of liquid water into the tunnel through cracks and imperfections in the concrete material. However, moisture can migrate through the concrete and EVA-based membrane materials by capillary and vapor diffusion mechanisms. These moisture transport mechanisms can have an influence on the degree of saturation, and may influence the pore pressures in the concrete material as well as risk of freeze-thaw damage of the concrete and membrane. The paper describes a detailed study of moisture transport material parameters, moisture condition in tunnel linings and climatic conditions tunnels in hard rock in Norway. These data have been included in a hygrothermal simulation model in the software WUFI for moisture transport to substantiate moisture transport and long-term effects on saturation of the concrete and membrane material. The findings suggest that EVA-based membranes exhibit significant water absorption and vapor transport properties although they are impermeable to liquid water flow. State-of-the-art sprayed concrete material applied with the wet mix method exhibits very low hydraulic conductivities, lower than 10-14 m/s, thus saturated conductive water flow is a very unlikely dominant transport mechanism. Moisture transport through the lining structure by capillary flow and vapor diffusion are calculated to approximately 3 cm3/m2 per day for lining thicknesses in the range of 25-35 cm and seasonal Nordic climate variations. The calculated moisture contents in the tunnel linings from the hygrothermal simulations are largely in agreement with the measured moisture contents in the tunnel linings. The findings also indicate that the concrete material exhibits

  18. Tunnel boring machine

    SciTech Connect

    Snyder, L. L.

    1985-07-09

    A tunnel boring machine for controlled boring of a curvilinear tunnel including a rotating cutter wheel mounted on the forward end of a thrust cylinder assembly having a central longitudinal axis aligned with the cutter wheel axis of rotation; the thrust cylinder assembly comprising a cylinder barrel and an extendable and retractable thrust arm received therein. An anchoring assembly is pivotally attached to the rear end of the cylinder barrel for anchoring the machine during a cutting stroke and providing a rear end pivot axis during curved cutting strokes. A pair of laterally extending, extendable and retractable arms are fixedly mounted at a forward portion of the cylinder barrel for providing lateral displacement in a laterally curved cutting mode and for anchoring the machine between cutting strokes and during straight line boring. Forward and rear transverse displacement and support assemblies are provided to facilitate cutting in a transversely curved cutting mode and to facilitate machine movement between cutting strokes.

  19. Uncooled tunneling infrared sensor

    NASA Technical Reports Server (NTRS)

    Kenny, Thomas W. (Inventor); Kaiser, William J. (Inventor); Podosek, Judith A. (Inventor); Vote, Erika C. (Inventor); Rockstad, Howard K. (Inventor); Reynolds, Joseph K. (Inventor)

    1994-01-01

    An uncooled infrared tunneling sensor in which the only moving part is a diaphragm which is deflected into contact with a micromachined silicon tip electrode prepared by a novel lithographic process. Similarly prepared deflection electrodes employ electrostatic force to control the deflection of a silicon nitride, flat diaphragm membrane. The diaphragm exhibits a high resonant frequency which reduces the sensor's sensitivity to vibration. A high bandwidth feedback circuit controls the tunneling current by adjusting the deflection voltage to maintain a constant deflection of the membrane which would otherwise change deflection depending upon incident infrared radiation. The resulting infrared sensor will meet or exceed the performance of all other broadband, uncooled, infrared sensors and can be miniaturized to pixel dimensions smaller than 100 .mu.m. The technology is readily implemented as a small-format linear array suitable for commercial and spacecraft applications.

  20. Possibility of hyperbolic tunneling

    SciTech Connect

    Lobo, Francisco S. N.; Mimoso, Jose P.

    2010-08-15

    Traversable wormholes are primarily useful as 'gedanken experiments' and as a theoretician's probe of the foundations of general relativity. In this work, we analyze the possibility of having tunnels in a hyperbolic spacetime. We obtain exact solutions of static and pseudo-spherically symmetric spacetime tunnels by adding exotic matter to a vacuum solution referred to as a degenerate solution of class A. The physical properties and characteristics of these intriguing solutions are explored, and through the mathematics of embedding it is shown that particular constraints are placed on the shape function, that differ significantly from the Morris-Thorne wormhole. In particular, it is shown that the energy density is always negative, and the radial pressure is positive, at the throat, contrary to the Morris-Thorne counterpart. Specific solutions are also presented by considering several equations of state, and by imposing restricted choices for the shape function or the redshift function.

  1. Tunnel magnetoresistance of diamondoids

    NASA Astrophysics Data System (ADS)

    Matsuura, Yukihito

    2016-10-01

    Tunnel magnetoresistance (TMR) of diamondoids has been predicted by first principles density functional theory. Diamantane was used as a basic molecular proxy for diamondoids because hydrogen atoms in the apical position are easily substituted for a thiol group. The pristine diamantane exhibited a low TMR ratio of 7%, and boron-substitution considerably decreased the TMR ratio. Conversely, nitrogen-substitution enhanced the TMR ratio by up to 20%. Heteroatom-substitution changes the tunneling probabilities by varying the molecular bond lengths. Furthermore, when the spins of the electrodes are parallel, the heteroatoms resulted in transmittance probabilities at an energy range near the Fermi level. Consequently, heteroatom-substitution can control the TMR ratios of diamondoids very well.

  2. Loads on Sprayed Waterproof Tunnel Linings in Jointed Hard Rock: A Study Based on Norwegian Cases

    NASA Astrophysics Data System (ADS)

    Holter, Karl Gunnar

    2014-05-01

    A composite tunnel lining system based on a sprayed waterproofing membrane combined with sprayed concrete is currently being considered for future Norwegian rail and road tunnels. Possible loading of the tunnel linings caused by water pressure is being investigated. This tunnel lining system consists of a waterproof membrane which, during application on the sprayed concrete lining, bonds mechanically to the sprayed concrete on either side. Hence, a continuous, sealing, and non-draining structure from the rock mass to the interior tunnel surface is formed in the walls and crown. Experiences from some successful recent projects with this lining system in Europe are reviewed. However, these experiences are not directly comparable to the Scandinavian hard rock tunnel lining approach, which utilizes a relatively thin sprayed and irregular concrete layer for permanent lining. When considering the sprayed membrane and sprayed concrete composite lining concept, introducing a partially sealing and undrained element in the lining, the experiences with the traditionally used lining systems in Norway need to be reconsidered and fully understood. A review of several hard rock tunnels with adverse conditions, in which the tunnel lining has been subject to load monitoring, shows that only very small loads in the tunnel linings occur. Recent investigations with in situ water pressure testing, including two sites with the composite sprayed membrane in a partially drained waterproof tunnel lining, are discussed. In a case with a cavern located in a hydraulically saturated rock mass subjected to approximately 8 bar hydrostatic pressure, a negative pressure gradient towards the tunnel lining has been measured. The investigation results from the Norwegian test sites indicate that no significant loading of the tunnel lining takes place in a hydraulically saturated rock when applying this composite waterproof tunnel lining in parts of the tunnel perimeter.

  3. Tarsal tunnel syndrome.

    PubMed

    Gould, John S

    2011-06-01

    Tarsal tunnel syndrome, unlike its similar sounding counterpart in the hand, is a significantly misunderstood clinical entity. Confusion concerning the anatomy involved, the presenting symptomatology, the appropriateness and significance of various diagnostic tests, conservative and surgical management, and, finally, the variability of reported results of surgical intervention attests to the lack of consensus surrounding this condition. The terminology involved in various diagnoses for chronic heel pain is also a hodgepodge of poorly understood entities.

  4. Full Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Installation of Full Scale Tunnel (FST) power plant. Virginia Public Service Company could not supply adequate electricity to run the wind tunnels being built at Langley. (The Propeller Research Tunnel was powered by two submarine diesel engines.) This led to the consideration of a number of different ideas for generating electric power to drive the fan motors in the FST. The main proposition involved two 3000 hp and two 1000 hp diesel engines with directly connected generators. Another, proposition suggested 30 Liberty motors driving 600 hp DC generators in pairs. For a month, engineers at Langley were hopeful they could secure additional diesel engines from decommissioned Navy T-boats but the Navy could not offer a firm commitment regarding the future status of the submarines. By mid-December 1929, Virginia Public Service Company had agreed to supply service to the field at the north end of the King Street Bridge connecting Hampton and Langley Field. Thus, new plans for FST powerplant and motors were made. Smith DeFrance described the motors in NACA TR No. 459: 'The most commonly used power plant for operating a wind tunnel is a direct-current motor and motor-generator set with Ward Leonard control system. For the FST it was found that alternating current slip-ring induction motors, together with satisfactory control equipment, could be purchased for approximately 30 percent less than the direct-current equipment. Two 4000-horsepower slip-ring induction motors with 24 steps of speed between 75 and 300 r.p.m. were therefore installed.'

  5. Diffraction as tunneling

    NASA Technical Reports Server (NTRS)

    Nussenzveig, H. M.; Wiscombe, W. J.

    1987-01-01

    A new approximation to the short-wavelength scattering amplitude from an impenetrable sphere is presented. It is uniform in the scattering angle and it is more accurate than previously known approximations (including Fock's theory of diffraction) by up to several orders of magnitude. It remains valid in the transition to long-wavelength scattering. It leads to a new physical picture of diffraction, as tunneling through an inertial barrier.

  6. Resonant Tunneling Spin Pump

    NASA Technical Reports Server (NTRS)

    Ting, David Z.

    2007-01-01

    The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling.

  7. Evaluating tunnel kiln performance

    SciTech Connect

    O`Connor, K.R.; Carty, W.M.; Ninos, N.J.

    1997-08-01

    Process improvements in the production of whitewares provide the potential for substantial savings for manufacturers. A typical whiteware manufacturer incurs an annual defective product loss of {approximately}$20 million when accounting for raw materials, energy, labor and waste disposal. Reduction in defective product loss of 1% could result in a savings in excess of $1 million annually. This study was designed to establish benchmarks for two conventional tunnel kilns used to bisque-fire dinnerware at Buffalo China Inc. (Buffalo, NY). The benchmark was established by assessing the current conditions and variability of the two tunnel kilns as a function of the fracture strength of sample bars that were made from production body. Sample bars were fired in multiple locations in both kilns to assess the conditions and variability of firing within each kiln. Comparison of strength results between the two kilns also was assessed. These comparisons were accomplished through applied statistical analysis, wherein significant statistical variations were identified and isolated for both tunnel kilns. The statistical methods and tools used in this analysis are readily accessible to manufacturers, thus allowing implementation of similar analysis, or benchmarking, in-house.

  8. Smart tunnel: Docking mechanism

    NASA Technical Reports Server (NTRS)

    Schliesing, John A. (Inventor); Edenborough, Kevin L. (Inventor)

    1989-01-01

    A docking mechanism is presented for the docking of a space vehicle to a space station comprising a flexible tunnel frame structure which is deployable from the space station. The tunnel structure comprises a plurality of series connected frame sections, one end section of which is attached to the space station and the other end attached to a docking module of a configuration adapted for docking in the payload bay of the space vehicle. The docking module is provided with trunnions, adapted for latching engagement with latches installed in the vehicle payload bay and with hatch means connectable to a hatch of the crew cabin of the space vehicle. Each frame section comprises a pair of spaced ring members, interconnected by actuator-attenuator devices which are individually controllable by an automatic control means to impart relative movement of one ring member to the other in six degrees of freedom of motion. The control means includes computer logic responsive to sensor signals of range and attitude information, capture latch condition, structural loads, and actuator stroke for generating commands to the onboard flight control system and the individual actuator-attenuators to deploy the tunnel to effect a coupling with the space vehicle and space station after coupling. A tubular fluid-impervious liner, preferably fabric, is disposed through the frame sections of a size sufficient to accommodate the passage of personnel and cargo.

  9. Evaluation of the Samsung 240T Analog and Digital, 24-Inch Diagonal 1920 x 1200 Pixel LCD Color Monitor

    DTIC Science & Technology

    2007-11-02

    improvement is achieved in part by eliminating a spurious extra part of a pixel ( phantom ) observed in analog mode. We achieved 1920 x 1200 digital addressing...by eliminating a spurious extra part of a pixel ( phantom ) observed in analog mode. We achieved 1920 x 1200 digital addressing by using an Elsa...signals, a phantom low-luminance subpixel shown in Figure 1 was observed at trailing object edges, vertical lines and even single pixels. This

  10. Development and testing of 11- and 24-inch hybrid motors under the joint government/industry IR&D program

    NASA Technical Reports Server (NTRS)

    Boardman, T. A.; Carpenter, R. L.; Goldberg, B. E.; Shaeffer, C. W.

    1993-01-01

    Establishment of a test facility and associated 11-in.-diameter motor for hybrid propulsion technology development at NASA's George C. Marshall Space Flight Center is discussed in this paper. Results of twenty 11-in.-diameter motor tests with a UTF-29901 (60 percent polycyclopentadiene, 40 percent hydroxyl-terminated polybutadiene)/gaseous oxygen propellant system are presented. Tests at this scale have developed fuel regression correlations for comparison with results of yet-to-be-completed, 24-in.-diameter motor tests; demonstrated combustion efficiency levels in the 95 percent range for both single- and multiple-port grain configurations; have shown smooth and stable throttling characteristics over flight-type throttle ranges; and have begun to establish criteria for stable combustion in hybrid motors. The testing of 24-in. motors has not as yet been initiated and is not addressed.

  11. Consumable Guide Electroslag Welding of 4 to 24 Inch Thick Carbon Steel Castings (The National Shipbuilding Research Program)

    DTIC Science & Technology

    1986-08-01

    ENGLISH SERBOCROAT SUBMERGED ARC, MANUAL METAL ARC, METAL INERT GAS AND CONSUMABLE GUIDE WELDS IN HY80 STEEL WERE PREPARED USING COMMERCIALLY AVAILABLE...JOINTS IN THICK PLATES OF MILD STEEL , QUENCHED AND TEMPERED LOW ALLOY STEELS QT35 AND HY80 AND 2-1/4 PER CENT CR-1 PER CENT MO STEEL ARE RECORDED. IT IS...THICKNESSES FROM 3/8 TO 24 IN. CAN BE WELDED, DEPENDING ON THE MACHINE CHOSEN. ONE MACHINE CAN WELD HY90, HY80 , AUSTENITIC STAINLESS AND HIGH-C STEELS , MONEL

  12. Microbubble tunneling in gel phantoms

    PubMed Central

    Caskey, Charles F.; Qin, Shengping; Dayton, Paul A.; Ferrara, Katherine W.

    2009-01-01

    Insonified microbubbles were observed in vessels within a gel with a Young’s modulus similar to that of tissue, demonstrating shape instabilities, liquid jets, and the formation of small tunnels. In this study, tunnel formulation occurred in the direction of the propagating ultrasound wave, where radiation pressure directed the contact of the bubble and gel, facilitating the activity of the liquid jets. Combinations of ultrasonic parameters and microbubble concentrations that are relevant for diagnostic imaging and drug delivery and that lead to tunnel formation were applied and the resulting tunnel formation was quantified. PMID:19425620

  13. Magnetic tunnel junction pattern technique

    NASA Astrophysics Data System (ADS)

    Chen, Eugene; Schwarz, Benjamin; Choi, Chang Ju; Kula, Witold; Wolfman, Jerome; Ounadjela, Kamel; Geha, Sam

    2003-05-01

    We have developed a magnetic tunnel junction (MTJ) pattern technique that involves transforming the magnetic layer above the tunnel barrier in unwanted areas into an insulator, thus providing insulation between different MTJ devices without suffering common tunnel barrier shorting problems. With this technique, 90%-100% yielding MTJ devices have been observed. MTJ results using this process are superior to an etching based process. Switching distribution of patterned magnetic bits is also narrower using this novel technique. Process control and the ability to stop on the tunnel barrier have been demonstrated.

  14. Tunneling above the crossover temperature.

    PubMed

    Alvarez-Barcia, Sonia; Flores, Jesús R; Kästner, Johannes

    2014-01-09

    Quantum mechanical tunneling of atoms plays a significant role in many chemical reactions. The crossover temperature between classical and quantum movement is a convenient preliminary indication of the importance of tunneling for a particular reaction. Here we show, using instanton theory, that quantum tunneling is possible significantly above this crossover temperature for specific forms of the potential energy surface. We demonstrate the effect on an analytic potential as well as a chemical system. While protons move asynchronously along a Grotthuss chain in the classical high-temperature range, the onset of tunneling results in a synchronization of their movement.

  15. Ferroelectric tunneling under bias voltages

    NASA Astrophysics Data System (ADS)

    Ma, Z. J.; Chen, G.; Zhou, P.; Mei, Z. H.; Zhang, T. J.

    2017-01-01

    Theoretical investigations of ferroelectric tunneling in a SrRuO3/BaTiO3/Pt junction were conducted, and critical expressions for the surface charge density in the electrodes and the potential distribution across the tunnel junction were derived. It was found that the screening charges associated with the ferroelectric polarization and the charging effect of the capacitor jointly contribute to the charges in the electrodes. A current-voltage study simulating the ‘read’ operation indicated that the tunneling electroresistance effect increases with the ferroelectric thickness, and the tunneling electroresistance values agree well with experimental results.

  16. Carpal tunnel syndrome

    PubMed Central

    Aroori, Somaiah; Spence, Roy AJ

    2008-01-01

    Carpal tunnel syndrome is one of the most common peripheral neuropathies. It affects mainly middle aged women. In the majority of patients the exact cause and pathogenesis of CTS is unclear. Although several occupations have been linked to increased incidence and prevalence of CTS the evidence is not clear. Occupational CTS is uncommon and it is essential to exclude all other causes particularly the intrinsic factors such as obesity before attributing it to occupation. The risk of CTS is high in occupations involving exposure to high pressure, high force, repetitive work, and vibrating tools. The classic symptoms of CTS include nocturnal pain associated with tingling and numbness in the distribution of median nerve in the hand. There are several physical examination tests that will help in the diagnosis of CTS but none of these tests are diagnostic on their own. The gold standard test is nerve conduction studies. However, they are also associated with false positive and false negative results. The diagnosis of CTS should be based on history, physical examination and results of electrophysiological studies. The patient with mild symptoms of CTS can be managed with conservative treatment, particularly local injection of steroids. However, in moderate to severe cases, surgery is the only treatment that provides cure. The basic principle of surgery is to increase the volume of the carpal tunnel by dividing transverse carpal ligament to release the pressure on the median nerve. Apart from early recovery and return to work there is no significant difference in terms of early and late complications and long-term pain relief between endoscopic and open carpal tunnel surgery. PMID:18269111

  17. Full Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction of Full Scale Tunnel (FST). In November 1929, Smith DeFrance submitted his recommendations for the general design of the Full Scale Wind Tunnel. The last on his list concerned the division of labor required to build this unusual facility. He believed the job had five parts and described them as follows: 'It is proposed that invitations be sent out for bids on five groups of items. The first would be for one contract on the complete structure; second the same as first, including the erection of the cones but not the fabrication, since this would be more of a shipyard job; third would cover structural steel, cover, sash and doors, but not cones or foundation; fourth, foundations; an fifth, fabrication of cones.' DeFrance's memorandum prompted the NACA to solicit estimates from a large number of companies. Preliminary designs and estimates were prepared and submitted to the Bureau of the Budget and Congress appropriated funds on February 20, 1929. The main construction contract with the J.A. Jones Company of Charlotte, North Carolina was signed one year later on February 12, 1930. It was a peculiar structure as the building's steel framework is visible on the outside of the building. DeFrance described this in NACA TR No. 459: 'The entire equipment is housed in a structure, the outside walls of which serve as the outer walls of the return passages. The over-all length of the tunnel is 434 feet 6 inches, the width 222 feet, and the maximum height 97 feet. The framework is of structural steel....' (pp. 292-293)

  18. Full Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction of Full-Scale Tunnel (FST). In November 1929, Smith DeFrance submitted his recommendations for the general design of the Full Scale Wind Tunnel. The last on his list concerned the division of labor required to build this unusual facility. He believed the job had five parts and described them as follows: 'It is proposed that invitations be sent out for bids on five groups of items. The first would be for one contract on the complete structure; second the same as first, including the erection of the cones but not the fabrication, since this would be more of a shipyard job; third would cover structural steel, cover, sash and doors, but not cones or foundation; fourth, foundations; and fifth, fabrication of cones.' DeFrance's memorandum prompted the NACA to solicit estimates from a large number of companies. Preliminary designs and estimates were prepared and submitted to the Bureau of the Budget and Congress appropriated funds on February 20, 1929. The main construction contract with the J.A. Jones Company of Charlotte, North Carolina was signed one year later on February 12, 1930. It was a peculiar structure as the building's steel framework is visible on the outside of the building. DeFrance described this in NACA TR No. 459: 'The entire equipment is housed in a structure, the outside walls of which serve as the outer walls of the return passages. The over-all length of the tunnel is 434 feet 6 inches, the width 222 feet, and the maximum height 97 feet. The framework is of structural steel....' (pp. 292-293).

  19. Recurrent tarsal tunnel syndrome.

    PubMed

    Gould, John S

    2014-09-01

    Recurrence of tarsal tunnel syndrome after surgery may be due to inadequate release, lack of understanding or appreciation of the actual anatomy involved, variations in the anatomy of the nerve(s), failure to execute the release properly, bleeding with subsequent scarring, damage to the nerve and branches, persistent hypersensitivity of the nerves, and preexisting intrinsic damage to the nerve. Approaches include more thorough release, use of barrier materials to decrease adherence of the nerve to surrounding tissues to avoid traction neuritis, excisions of neuromas using conduits, and consideration of nerve stimulators and systemic medications to deal with persistent neural pain.

  20. Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Chennault, Jonathan

    2004-01-01

    The Icing Research Tunnel in Building 11 at the NASA Glenn Research Center is committed to researching the effects of in flight icing on aircraft and testing ways to stop the formation of hazardous icing conditions on planes. During this summer, I worked here with Richard DelRosa, the lead engineer for this area. address one of the major concerns of aviation: icing conditions. During the war, many planes crashed (especially supply planes going over the.Himalayas) because ice built up in their wings and clogged the engines. To this day, it remains the largest ice tunnel in the world, with a test section that measures 6 feet high, 9 feet long, and 20 feet wide. It can simulate airspeeds from 50 to 300 miles per hour at temperatures as low as -50 Fahrenheit. Using these capabilities, IRT can simulate actual conditions at high altitudes. The first thing I did was creating a cross reference in Microsoft Excel. It lists commands for the DPU units that control the pressure and temperature variations in the tunnel, as well as the type of command (keyboard, multiplier, divide, etc). The cross reference also contains the algorithm for every command, and which page it is listed in on the control sheet (visual Auto-CAD graphs, which I helped to make). I actually spent most of the time on the computer using Auto-CAD. I drew a diagram of the entire icing tunnel and then drew diagrams of its various parts. Between my mentor and me, we have drawings of every part of it, from the spray bars to the thermocouples, power cabinets, input-output connectors for power systems, and layouts of various other machines. I was also responsible for drawing schematics for the Escort system (which controls the spray bars), the power system, DPUs, and other electrical systems. In my spare time, I am attempting to build and program the "toddler". Toddler is a walking robot that I have to program in PBASIC language. When complete, it should be able to walk on level terrain while avoiding obstacles in

  1. Icing Cloud Calibration of the NASA Glenn Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Ide, Robert F.; Oldenburg, John R.

    2001-01-01

    The icing research tunnel at the NASA Glenn Research Center underwent a major rehabilitation in 1999, necessitating recalibration of the icing clouds. This report describes the methods used in the recalibration, including the procedure used to establish a uniform icing cloud and the use of a standard icing blade technique for measurement of liquid water content. The instruments and methods used to perform the droplet size calibration are also described. The liquid water content/droplet size operating envelopes of the icing tunnel are shown for a range of airspeeds and compared to the FAA icing certification criteria. The capabilities of the IRT to produce large droplet icing clouds is also detailed.

  2. The Langley Wind Tunnel Enterprise

    NASA Technical Reports Server (NTRS)

    Paulson, John W., Jr.; Kumar, Ajay; Kegelman, Jerome T.

    1998-01-01

    After 4 years of existence, the Langley WTE is alive and growing. Significant improvements in the operation of wind tunnels have been demonstrated and substantial further improvements are expected when we are able to truly address and integrate all the processes affecting the wind tunnel testing cycle.

  3. Supersonic Wind Tunnel Test Section

    NASA Technical Reports Server (NTRS)

    1957-01-01

    8ft x 6ft Supersonic Wind Tunnel Test-Section showing changes made in Stainless Steel walls with 17 inch inlet model installation. The model is the ACN Nozzle model used for aircraft engines. The Supersonic Wind Tunnel is located in the Lewis Flight Propulsion Laboratory, now John H. Glenn Research Center

  4. Two tunnels to inflation

    SciTech Connect

    Aguirre, Anthony; Johnson, Matthew C.

    2006-06-15

    We investigate the formation via tunneling of inflating (false-vacuum) bubbles in a true-vacuum background, and the reverse process. Using effective potentials from the junction condition formalism, all true- and false-vacuum bubble solutions with positive interior and exterior cosmological constant, and arbitrary mass are catalogued. We find that tunneling through the same effective potential appears to describe two distinct processes: one in which the initial and final states are separated by a wormhole (the Farhi-Guth-Guven mechanism), and one in which they are either in the same hubble volume or separated by a cosmological horizon. In the zero-mass limit, the first process corresponds to the creation of an inhomogenous universe from nothing, while the second mechanism is equivalent to the nucleation of true- or false-vacuum Coleman-De Luccia bubbles. We compute the probabilities of both mechanisms in the WKB approximation using semiclassical Hamiltonian methods, and find that--assuming both process are allowed--neither mechanism dominates in all regimes.

  5. Carpal tunnel syndrome.

    PubMed

    Chammas, M

    2014-04-01

    Carpal tunnel syndrome is the commonest entrapment neuropathy and is due to combined compression and traction on the median nerve at the wrist. It is often idiopathic. Although spontaneous resolution is possible, the usual natural evolution is slow progression. Diagnosis is mainly clinical depending on symptoms and provocative tests. An electromyogram is recommended preoperatively and in cases of work-related disease. Medical treatment is indicated early on or in cases with no deficit and consists of steroid injection in the canal or a night splint in neutral wrist position. Surgical treatment is by section of the flexor retinaculum and is indicated in resistance to medical treatment, in deficit or acute cases. Mini-invasive techniques such as endoscopic and mini-open approaches to carpal tunnel release with higher learning curves are justified by the shorter functional recovery time compared to classical surgery, but with identical long-term results. The choice depends on the surgeon's preference, patient information, stage of severity, etiology and availability of material. Results are satisfactory in 90% of cases. Nerve recovery depends on the stage of severity as well as general patient factors. Recovery of force takes about 2-3 months after the disappearance of 'pillar pain'. This operation has a benign reputation with a 0.2-0.5% reported neurovascular complication rate.

  6. Tunneling magnetic force microscopy

    NASA Technical Reports Server (NTRS)

    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.

  7. Tunneling in Superconductors

    NASA Astrophysics Data System (ADS)

    Giaever, Ivar

    2002-03-01

    It has been said that Thomas Edison's greatest invention was that of the "Research Laboratory" as a social institution. My greatest discovery was when I learned at 29 years of age that it was possible to work in such an institution and get paid for doing research. I had become interested in physics, gotten a job at General Electric Research Laboratory and found a great mentor in John C. Fischer, who besides instructing me in physics told me that sooner or later we all would become historians of science. I guess for me that time is now, because I have been asked to tell you about my second greatest discovery: Tunneling in superconductors. My great fortune was to be at the right place at the right time, where I had access to outstanding and helpful (not necessary an oxymoron) physicists. Hopefully I will be able to convey to you some of the fun and excitement of that area in this recollection. If you become real interested you may find a written version in my Nobel Prize talk: "Electron Tunneling and Superconductivity" Les Prix Nobel en 1973 or Science 183, 1253-1258 1974 or Reviews of Modern Physics 46 (2), 245-250 1974

  8. 15-Foot Spin Tunnel

    NASA Technical Reports Server (NTRS)

    1935-01-01

    A researcher is launching a model into the tunnel airstream of the 15-Foot Spin Tunnel. Charles Zimmerman wrote in NASA TR No. 557: 'After the observations have been made, the model is lowered into a net held in the air stream by one of the operators or into a large bowl-shaped net at the bottom of the test section. When lowered into the large net, the model is retrieved with a long- handled clamp.' (p. 267) 'The models used are generally 1/10 to 1/16 scale. The size of the models is limited by the wing span and the wing loading. The maximum allowable span is about 36 inches; the maximum wing loading is about 1.3 pounds per square foot.' (p. 266) 'Balsa wood is the usual structural material because of its low density. It is necessary to hollow out the after portion of the fuselage and to cut out a large portion of the wood in the wings to permit proper mass distribution. The wing cut-outs are covered with silk tissue paper. The leading and trailing edges and tips of the wings are fitted with strips of spruce, pattern pine, or bamboo inset into the edge of the balsa to prevent disfigurement from accidental blows or from striking the safety netting. Lead is used for ballast.' (p. 266)

  9. Tunneling in thin MOS structures

    NASA Technical Reports Server (NTRS)

    Maserjian, J.

    1974-01-01

    Recent results on tunneling in thin MOS structures are described. Thermally grown SiO2 films in the thickness range of 22-40 A have been shown to be effectively uniform on an atomic scale and exhibit an extremely abrupt oxide-silicon interface. Resonant reflections are observed at this interface for Fowler-Nordheim tunneling and are shown to agree with the exact theory for a trapezoidal barrier. Tunneling at lower fields is consistent with elastic tunneling into the silicon direct conduction band and, at still lower fields, inelastic tunneling into the indirect conduction band. Approximate dispersion relations are obtained over portions of the silicon-dioxide energy gap and conduction band.

  10. Calibration of the Langley 16-foot transonic tunnel with test section air removal

    NASA Technical Reports Server (NTRS)

    Corson, B. W., Jr.; Runckel, J. F.; Igoe, W. B.

    1974-01-01

    The Langley 16-foot transonic tunnel with test section air removal (plenum suction) was calibrated to a Mach number of 1.3. The results of the calibration, including the effects of slot shape modifications, test section wall divergence, and water vapor condensation, are presented. A complete description of the wind tunnel and its auxiliary equipment is included.

  11. TOUGH2 model of the G-tunnel heater test

    SciTech Connect

    Ho, C.K.; Eaton, R.R.

    1995-12-01

    An experiment designed to observe water migration under non-isothermal conditions in welded tuff was performed in 1980 in the welded portion of the Grouse Canyon Member in the U12g tunnel (G-tunnel) at Rainier Mesa. Significant amounts of water were observed to migrate towards a heated hole bored into the welded tuff. The water migration was attributed to vapor phase diffusion, but other processes such as gravity driven flow were not considered and may have contributed significantly to the observed water migration. The modeling studies presented here address processes of water migration near heated regions in partially saturated tuff. The multiphase, non-isothermal numerical code TOUGH2 was used to model the G-Tunnel heater experiment. The numerical simulation consisted of 10 days of heating at 1000 W. Temperatures, liquid saturations, gas pressures, gas and liquid velocities, and vapor mass fractions were recorded to determine the processes affecting water migration. Results of the simulation indicated that water migration near heated tuffaceous rock involves a combination of processes. Gas-phase advection and diffusion transported water vapor that was evaporated near the heater toward outer regions. Water vapor condensed in cooler regions away from the heater, increasing the saturations. As liquid water accumulated in the heater borehole, capillary suction pulled some of the liquid toward the drier heated region while gravity drained some of the liquid away from the heater. In natural systems, high permeability fractures could mimic the role of the heater hole.

  12. Study of ice accretion on icing wind tunnel components

    NASA Technical Reports Server (NTRS)

    Newton, J. E.; Olsen, W.

    1986-01-01

    In a closed loop icing wind tunnel the icing cloud is simulated by introducing tiny water droplets through an array of nozzles upstream of the test section. This cloud will form ice on all tunnel components (e.g., turning vanes, inlet guide vanes, fan blades, and the heat exchanger) as the cloud flows around the tunnel. These components must have the capacity to handle their icing loads without causing significant tunnel performance degradation during the course of an evening's run. To aid in the design of these components for the proposed Altitude Wind Tunnel (AWT) at NASA Lewis Research Center the existing Icing Research Tunnel (IRT) is used to measure icing characteristics of the IRT's components. The results from the IRT are scaled to the AWT to account for the AWT's larger components and higher velocities. The results show that from 90 to 45 percent of the total spray cloud froze out on the heat exchanger. Furthermore, the first set of turning vanes downstream of the test section, the FOD screen and the fan blades show significant ice formation. The scaling shows that the same results would occur in the AWT.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. The virtual wind tunnel

    NASA Technical Reports Server (NTRS)

    Bryson, Steve; Levit, Creon

    1992-01-01

    Consideration is given to the design and implementaion of a virtual environment linked to a graphics workstation for the visualization of complex fluid flows. The user wears a stereo head-tracked display which displays 3D information and an instrumented glove to intuitively position flow-visualization tools. The idea is to create for the user an illusion that he or she is actually in the flow manipulating visualization tools. The user's presence does not disturb the flow so that sensitive flow areas can be easily investigated. The flow is precomputed and can be investigated at any length scale and with control over time. Particular attention is given to the visualization structures and their interfaces in the virtual environment, hardware and software, and the performance of the virtual wind tunnel using flow past a tapered cylinder as an example.

  15. Cryogenic Wind Tunnels.

    DTIC Science & Technology

    1980-07-01

    4 Ua 0 - mI - L - In 04 4 0 .e NA rA 0O r, 41 --t4..4 Z~, 4A e4 LANO wIU a~I. . 4 *0r I .- . . . .44 󈧰 6j.4. oo I~~~ 0 A I 1 I 4 L tr- A I N 𔃺 LA...sometimes appropriate for industrial aerodynamics. 1.00 LINE pr ATM Tr K LINE Pt. ATM Tt’ K .9 -1 3D .9_ _ _ P. 09 390 HELIUM IDEAL .94 HELIUM IDEA L 𔃿 .92...L8CRYOGENIC WIND TUNNELS. (U) UNCLASSIFIED AGARDLS111" 1111 18* 111122 1111 111 - 1I1111.25 IIQ14 111.6 MI (NO(OPY RP tHI1IN Illki AGAVEI.11 C i

  16. Anterior tarsal tunnel syndrome.

    PubMed

    DiDomenico, Lawrence A; Masternick, Eric B

    2006-07-01

    Compression of the deep peroneal nerve is commonly referred to as anterior tarsal tunnel syndrome. Although rare, this syndrome remains poorly diagnosed. The syndrome is characterized by pain, weakness, and sensory changes of the foot and ankle. Non-operative measures should be attempted to reduce or remove the external compression along the anterior aspect of the foot and ankle. Other options include shoe modifications, cortisone injections,and physical therapy. If conservative management fails to relieve the symptoms, surgical decompression of the entrapped nerve can be performed. The deep peroneal nerve is released from compressive forces in the entrapment site. This can be performed at the more proximal level at the extensor retinaculum or more distally at the level of the tarsal metatarsal site.

  17. Tunnelling microscopy of DNA

    NASA Astrophysics Data System (ADS)

    Selci, Stefano; Cricenti, Antonio

    1991-01-01

    Uncoated DNA molecules marked with an activated tris (1-aziridinyl) phosphine oxide (TAPO) solution were deposited on gold substrates and imaged in air with a high resolution Scanning Tunnelling Microscope (STM). The STM operated simultaneously in the constant-current and gap-modulated mode. Highly reproducible STM images have been obtained and interpreted in terms of expected DNA structure. The main periodicity, regularly presented in molecules several hundred Ångstrom long, ranges from 25 Å to 35 Å with an average diameter of 22 Å. Higher resolution images of the minor groove have revealed the phosphate groups along the DNA backbones. Constant-current images of TAPO deposited on gold show a crystalline structure of rows of molecules with a side-by-side spacing of 3 Å.

  18. Mars Surface Tunnel Element Concept

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle A.; Jefferies, Sharon; Howe, A. Scott; Howard, Robert; Mary, Natalie; Watson, Judith; Lewis, Ruthan

    2016-01-01

    When the first human visitors on Mars prepare to return to Earth, they will have to comply with stringent planetary protection requirements. Apollo Program experience warns that opening an EVA hatch directly to the surface will bring dust into the ascent vehicle. To prevent inadvertent return of potential Martian contaminants to Earth, careful consideration must be given to the way in which crew ingress their Mars Ascent Vehicle (MAV). For architectures involving more than one surface element-such as an ascent vehicle and a pressurized rover or surface habitat-a retractable tunnel that eliminates extravehicular activity (EVA) ingress is an attractive solution. Beyond addressing the immediate MAV access issue, a reusable tunnel may be useful for other surface applications, such as rover to habitat transfer, once its primary mission is complete. A National Aeronautics and Space Administration (NASA) team is studying the optimal balance between surface tunnel functionality, mass, and stowed volume as part of the Evolvable Mars Campaign (EMC). The study team began by identifying the minimum set of functional requirements needed for the tunnel to perform its primary mission, as this would presumably be the simplest design, with the lowest mass and volume. This Minimum Functional Tunnel then becomes a baseline against which various tunnel design concepts and potential alternatives can be traded, and aids in assessing the mass penalty of increased functionality. Preliminary analysis indicates that the mass of a single-mission tunnel is about 237 kg, not including mass growth allowance.

  19. Full-Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Steam pile driver for foundation of Full-Scale Tunnel (FST). In 1924, George Lewis, Max Munk and Fred Weick began to discuss an idea for a wind tunnel large enough to test a full-scale propeller. Munk sketched out a design for a tunnel with a 20-foot test section. The rough sketches were presented to engineers at Langley for comment. Elliott Reid was especially enthusiastic and he wrote a memorandum in support of the proposed 'Giant Wind Tunnel.' At the end of the memorandum, he appended the recommendation that the tunnel test section should be increased to 30-feet diameter so as to allow full-scale testing of entire airplanes (not just propellers). Reid's idea for a full-scale tunnel excited many at Langley but the funds and support were not available in 1924. Nonetheless, Elliot Reid's idea would eventually become reality. In 1928, NACA engineers began making plans for a full-scale wind tunnel. In February 1929, Congress approved of the idea and appropriated $900,000 for construction. Located just a few feet from the Back River, pilings to support the massive building's foundation had to be driven deep into the earth. This work began in the spring of 1929 and cost $11,293.22

  20. Full-Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Pile driving for foundation of Full-Scale Tunnel (FST). In 1924, George Lewis, Max Munk and Fred Weick began to discuss an idea for a wind tunnel large enough to test a full-scale propeller. Munk sketched out a design for a tunnel with a 20-foot test section. The rough sketches were presented to engineers at Langley for comment. Elliott Reid was especially enthusiastic and he wrote a memorandum in support of the proposed 'Giant Wind Tunnel.' At the end of the memorandum, he appended the recommendation that the tunnel test section should be increased to 30-feet diameter so as to allow full-scale testing of entire airplanes (not just propellers). Reid's idea for a full-scale tunnel excited many at Langley but the funds and support were not available in 1924. Nonetheless, Elliot Reid's idea would eventually become reality. In 1928, NACA engineers began making plans for a full-scale wind tunnel. In February 1929, Congress approved of the idea and appropriated $900,000 for construction. Located just a few feet from the Back River, pilings to support the massive building's foundation had to be driven deep into the earth. This work began in the spring of 1929 and cost $11,293.22.

  1. Full-Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1930-01-01

    General view of concrete column base for Full-Scale Tunnel (FST). In 1924, George Lewis, Max Munk and Fred Weick began to discuss an idea for a wind tunnel large enough to test a full-scale propeller. Munk sketched out a design for a tunnel with a 20-foot test section. The rough sketches were presented to engineers at Langley for comment. Elliott Reid was especially enthusiastic and he wrote a memorandum in support of the proposed 'Giant Wind Tunnel.' At the end of the memorandum, he appended the recommendation that the tunnel test section should be increased to 30-feet diameter so as to allow full-scale testing of entire airplanes (not just propellers). Reid's idea for a full-scale tunnel excited many at Langley but the funds and support were not available in 1924. Nonetheless, Elliot Reid's idea would eventually become reality. In 1928, NACA engineers began making plans for a full-scale wind tunnel. In February 1929, Congress approved of the idea and appropriated $900,000 for construction. Work on the foundation began in the spring of 1929 and cost $11,293.22.

  2. Quantum Tunneling and Complex Trajectories

    NASA Astrophysics Data System (ADS)

    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.

  3. Seismic Analysis of Tunnel Boring Machine Signals at Kerckhoff Tunnel

    DTIC Science & Technology

    1983-08-01

    of the MSHA system to detect a large tunnel boring machine (TBM) operating in granite at depths in excess of 1300 ft, the degree of accuracy of the...determined that the TBM could be detected at a horizontal range of about 80000 ft and the tunnel boring machine could be accurately located within approximately 100 ft at a slant range of approximately 5000 ft.

  4. Use of Automatic Target Recognition System for the Displacement Measurements in a Small Diameter Tunnel Ahead of the Face of the Motorway Tunnel During Excavation.

    PubMed

    Klopčič, Jure; Ambrožič, Tomaž; Marjetič, Aleš; Bogatin, Sonja; Pulko, Boštjan; Logar, Janko

    2008-12-10

    During construction of the Šentvid tunnel a unique opportunity arose to measure the 3D displacements ahead of the motorway tunnel excavation face, since the exploratory tunnel was already constructed in the axis of the main tunnel. According to reviewed literature such measurements had not been performed yet and several problems regarding equipment and complete scheme of the experiment needed to be overcome. The paper gives a brief description of the Šentvid tunnel project, presents significant factors that affected the choice of the geodetic equipment and describes the scheme of the experiment. A special attention is focused on the problems relating to the operation of the instrument in demanding environmental conditions (water, dust).

  5. Use of Automatic Target Recognition System for the Displacement Measurements in a Small Diameter Tunnel Ahead of the Face of the Motorway Tunnel During Excavation

    PubMed Central

    Klopčič, Jure; Ambrožič, Tomaž; Marjetič, Aleš; Bogatin, Sonja; Pulko, Boštjan; Logar, Janko

    2008-01-01

    During construction of the Šentvid tunnel a unique opportunity arose to measure the 3D displacements ahead of the motorway tunnel excavation face, since the exploratory tunnel was already constructed in the axis of the main tunnel. According to reviewed literature such measurements had not been performed yet and several problems regarding equipment and complete scheme of the experiment needed to be overcome. The paper gives a brief description of the Šentvid tunnel project, presents significant factors that affected the choice of the geodetic equipment and describes the scheme of the experiment. A special attention is focused on the problems relating to the operation of the instrument in demanding environmental conditions (water, dust). PMID:27873980

  6. Water

    MedlinePlus

    ... 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, ...

  7. Compact, single-tube scanning tunneling microscope with thermoelectric cooling

    NASA Astrophysics Data System (ADS)

    Jobbins, Matthew M.; Agostino, Christopher J.; Michel, Jolai D.; Gans, Ashley R.; Kandel, S. Alex

    2013-10-01

    We have designed and built a scanning tunneling microscope with a compact inertial-approach mechanism that fits inside the piezoelectric scanner tube. Rigid construction allows the microscope to be operated without the use of external vibration isolators or acoustic enclosures. Thermoelectric cooling and a water-ice bath are used to increase temperature stability when scanning under ambient conditions.

  8. Flatback airfoil wind tunnel experiment.

    SciTech Connect

    Mayda, Edward A.; van Dam, C.P.; Chao, David D.; 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.

  9. Carpal Tunnel Syndrome (For Kids)

    MedlinePlus

    ... tunnel syndrome may have trouble typing on the computer or playing a video game. In fact, repetitive ... times as many women as men have CTS. Computer operators, assembly-line workers, and hair stylists are ...

  10. Tunnel construction for a desertron

    SciTech Connect

    Hinterberger, H.; Huson, F.R.

    1983-03-27

    The tunnel in this model of construction is 3-1/2 feet wide by 5 feet high. It is assumed that the tunnel contains a rail system and guidance system for: (1) An enclosed car used for transport of 2 people and some tools. (2) A magnet mover. This robot could pick up a magnet and transport it at about 10 miles per hour. (3) An alignment robot. The alignment robot would intercept E.M. waves (microwaves, lasers) to determine its position in the tunnel. Then workers could come along inside the tunnel hoop and nail it together and to the floor. The trench would then be back-filled with a 1 foot berm on top. A rail system would be installed and a support stand for the magnet.

  11. Electron tunneling in proteins program.

    PubMed

    Hagras, Muhammad A; Stuchebrukhov, Alexei A

    2016-06-05

    We developed a unique integrated software package (called Electron Tunneling in Proteins Program or ETP) which provides an environment with different capabilities such as tunneling current calculation, semi-empirical quantum mechanical calculation, and molecular modeling simulation for calculation and analysis of electron transfer reactions in proteins. ETP program is developed as a cross-platform client-server program in which all the different calculations are conducted at the server side while only the client terminal displays the resulting calculation outputs in the different supported representations. ETP program is integrated with a set of well-known computational software packages including Gaussian, BALLVIEW, Dowser, pKip, and APBS. In addition, ETP program supports various visualization methods for the tunneling calculation results that assist in a more comprehensive understanding of the tunneling process. © 2016 Wiley Periodicals, Inc.

  12. Tunneling Plasmonics in Bilayer Graphene.

    PubMed

    Fei, Z; Iwinski, E G; Ni, G X; Zhang, L M; Bao, W; Rodin, A S; Lee, Y; Wagner, M; Liu, M K; Dai, S; Goldflam, M D; Thiemens, M; Keilmann, F; Lau, C N; Castro-Neto, A H; Fogler, M M; Basov, D N

    2015-08-12

    We report experimental signatures of plasmonic effects due to electron tunneling between adjacent graphene layers. At subnanometer separation, such layers can form either a strongly coupled bilayer graphene with a Bernal stacking or a weakly coupled double-layer graphene with a random stacking order. Effects due to interlayer tunneling dominate in the former case but are negligible in the latter. We found through infrared nanoimaging that bilayer graphene supports plasmons with a higher degree of confinement compared to single- and double-layer graphene, a direct consequence of interlayer tunneling. Moreover, we were able to shut off plasmons in bilayer graphene through gating within a wide voltage range. Theoretical modeling indicates that such a plasmon-off region is directly linked to a gapped insulating state of bilayer graphene, yet another implication of interlayer tunneling. Our work uncovers essential plasmonic properties in bilayer graphene and suggests a possibility to achieve novel plasmonic functionalities in graphene few-layers.

  13. Tunneling Plasmonics in Bilayer Graphene

    NASA Astrophysics Data System (ADS)

    Fei, Z.; Iwinski, E. G.; Ni, G. X.; Zhang, L. M.; Bao, W.; Rodin, A. S.; Lee, Y.; Wagner, M.; Liu, M. K.; Dai, S.; Goldflam, M. D.; Thiemens, M.; Keilmann, F.; Lau, C. N.; Castro-Neto, A. H.; Fogler, M. M.; Basov, D. N.

    2015-08-01

    We report experimental signatures of plasmonic effects due to electron tunneling between adjacent graphene layers. At sub-nanometer separation, such layers can form either a strongly coupled bilayer graphene with a Bernal stacking or a weakly coupled double-layer graphene with a random stacking order. Effects due to interlayer tunneling dominate in the former case but are negligible in the latter. We found through infrared nano-imaging that bilayer graphene supports plasmons with a higher degree of confinement compared to single- and double-layer graphene, a direct consequence of interlayer tunneling. Moreover, we were able to shut off plasmons in bilayer graphene through gating within a wide voltage range. Theoretical modeling indicates that such a plasmon-off region is directly linked to a gapped insulating state of bilayer graphene: yet another implication of interlayer tunneling. Our work uncovers essential plasmonic properties in bilayer graphene and suggests a possibility to achieve novel plasmonic functionalities in graphene few-layers.

  14. Guidelines for tunneling in enzymes

    PubMed Central

    Moser, Christopher C.; Ross Anderson, J. L.; Dutton, P. Leslie

    2010-01-01

    Summary Here we extend the engineering descriptions of simple, single-electron-tunneling chains common in oxidoreductases to quantify sequential oxidation-reduction rates of two-or-more electron cofactors and substrates. We identify when nicotinamides may be vulnerable to radical mediated oxidation-reduction and merge electron-tunneling expressions with the chemical rate expressions of Eyring. The work provides guidelines for the construction of new artificial oxidoreductases inspired by Nature but adopting independent design and redox engineering. PMID:20460101

  15. Study on molecular cavity of oligoamide macrocycles by using scanning tunneling microscopy.

    PubMed

    Wang, Yibing; Li, Yibao; Luo, Yin; Xu, Meng; Zhang, Xuemei; Guo, Yuanyuan; Wei, Guanghong; Yuan, Lihua; Gong, Bing; Yang, Yanlian; Wang, Chen

    2012-11-12

    The molecular structures and assembly structures of aromatic oligoamide macrocycles are identified by using scanning tunneling microscopy at liquid/solid interface, which shows persistent shapes, tunable cavity sizes, and binding of water molecules.

  16. 15. Photocopy of a photograph1921 ORIGINAL HEADRACE TUNNEL FOR WESTSIDE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. Photocopy of a photograph--1921 ORIGINAL HEADRACE TUNNEL FOR WESTSIDE PLANT - American Falls Water, Power & Light Company, Island Power Plant, Snake River, below American Falls Dam, American Falls, Power County, ID

  17. PUREX Storage Tunnels dangerous waste permit application. Revision 1, Volume 1

    SciTech Connect

    Not Available

    1991-12-01

    The PUREX Storage Tunnels are a mixed waste storage unit consisting of two underground railroad tunnels: Tunnel Number 1 designated 218-E-14 and Tunnel Number 2 designated 218-E-15. The two tunnels are connected by rail to the PUREX Plant and combine to provide storage space for 48 railroad cars (railcars). The PUREX Storage Tunnels provide a long-term storage location for equipment removed from the PUREX Plant. Transfers into the PUREX Storage Tunnels are made on an as-needed basis. Radioactively contaminated equipment is loaded on railcars and remotely transferred by rail into the PUREX Storage Tunnels. Railcars act as both a transport means and a storage platform for equipment placed into the tunnels. This report consists of part A and part B. Part A reports on amounts and locations of the mixed water. Part B permit application consists of the following: Facility Description and General Provisions; Waste Characteristics; Process Information; Groundwater Monitoring; Procedures to Prevent Hazards; Contingency Plan; Personnel Training; Exposure Information Report.

  18. Zener tunneling in semiconductor superlattices.

    PubMed

    Romanova, J Yu; Demidov, E V; Mourokh, L G; Romanov, Yu A

    2011-08-03

    Characteristics of miniband tunneling and Wannier-Stark levels in semiconductor superlattices are studied as regards their dependence on the symmetry of the unit cells and the type of miniband structure. We modify the k ⋅ p method into a k ⋅ v form and on this basis generalize the Zener formula for the inter-band tunneling in homogeneous semiconductors to the case of inter-miniband tunneling in superlattices, account being taken of the inhomogeneity of the electron effective mass. The corresponding sum rule for the effective masses in such structures is obtained. We develop a unified matrix approach for the calculation of the inter-miniband tunneling and Wannier-Stark levels in the case of an arbitrary number of minibands. We study the electric field dependence of the probability of inter-miniband tunneling for an electron transferred through the Brillouin minizone only once. The peculiarities of the inter-miniband transitions for the case where this transfer is repeated are also examined for various unit cells and miniband structures of the superlattice. In addition, we discuss mechanisms and specific features of the resonant Zener tunneling and its manifestations in electron transport.

  19. Drift studies--comparison of field and wind tunnel experiments.

    PubMed

    Stadler, R; Regenauer, W

    2005-01-01

    Drift at pesticide application leads to a pollution of non-target crops, non-target species and surface water. Spray drift is influenced by many factors like environmental conditions, vegetation, technical conditions, and physical properties of the tank mixes and influenced by Chemicals. Field experiments to characterise spray drift effects with the risk of permanent changing weather conditions can be supported by wind tunnel experiments. Wind tunnel experiments do not lead to the same soil deposition curves like field experiments, but the ratio of drift reduction potential is comparable.

  20. Hysteresis of boiling for different tunnel-pore surfaces

    NASA Astrophysics Data System (ADS)

    Pastuszko, Robert; Piasecka, Magdalena

    2015-05-01

    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.

  1. 5-foot Vertical Wind Tunnel

    NASA Technical Reports Server (NTRS)

    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

  2. Magnetic tunnel junctions utilizing diamond-like carbon tunnel barriers

    NASA Astrophysics Data System (ADS)

    Cadieu, F. J.; Chen, Li; Li, Biao

    2002-05-01

    We have devised a method whereby thin particulate-free diamond-like carbon films can be made with good adhesion onto even room-temperature substrates. The method employs a filtered ionized carbon beam created by the vacuum impact of a high-energy, approximately 1 J per pulse, 248 nm excimer laser onto a carbon target. The resultant deposition beam can be steered and deflected by magnetic and electric fields to paint a specific substrate area. An important aspect of this deposition method is that the resultant films are particulate free and formed only as the result of atomic species impact. The vast majority of magnetic tunnel junctions utilizing thin metallic magnetic films have employed a thin oxidized layer of aluminum to form the tunnel barrier. This has presented reproducibility problems because the indicated optimal barrier thickness is only approximately 13 Å thick. Magnetic tunnel junctions utilizing Co and permalloy films made by evaporation and sputtering have been fabricated with an intervening diamond-like carbon tunnel barrier. The diamond-like carbon thickness profile has been tapered so that seven junctions with different barrier thickness can be formed at once. Magnetoresistive (MR) measurements made between successive permalloy strip ends include contributions from two junctions and from the permalloy and Co strips that act as current leads to the junctions. Magnetic tunnel junctions with thicker carbon barriers exhibit MR effects that are dominated by that of the permalloy strips. Since these tunnel barriers are formed without the need for oxygen, complete tunnel junctions can be formed with all high-vacuum processing.

  3. Spin-dependent tunneling in magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Davis, Albert Hamilton, Jr.

    In this work I present results of a theoretical study of the intrinsic response of ferromagnetic tunnel junctions (MTJ's). The goal of the work has been to understand the underlying physics in order to describe the intrinsic portion of the observed behavior. Specifically, I present a free electron tunneling model which predicts that the magneto-conductance ratio (ΔG/G) or tunneling magneto-resistance (TMR) in high quality MTJs is dominated by the intrinsic response. The model assumes an effective tunneling electronic structure which has been constructed from parameters extracted from first principles calculations and a simple barrier whose effective height and thickness are deduced from the experiments. This model does not utilize the polarization (P) of the density of states (DOS) as an input parameter, but rather calculates the conductance for each spin channel and configuration in order to calculate TMR directly. The process of matching spin-dependent tunneling states with spin-independent barrier states produces a spin-dependent T-matrix which is the main difference between this model and other prevalent models which have been built upon Julliere's model (M. Julliere, Phys. Lett. 54 225, 1975). The effect of bias is handled by increasing the chemical potential on one side of the barrier, and the effect of temperature is included via Fermi smearing and the temperature dependent magnetic band structure. The model predicts that MTJ's are quite sensitive to changes in the magnetic band structure. This explains both the large temperature dependence of TMR and the high sensitivity of MTJ's to magnetic fields. The model strongly supports the assertion that only a portion of the total DOS is relevant to spin-dependent tunneling (SDT) and that the bands which supply the tunneling electrons are essentially Stoner split. I conclude with a consideration of asymmetric TMR and a short first principles study of fcc magnetic alloys which gives some insight into the relative

  4. 15-Foot Spin Tunnel

    NASA Technical Reports Server (NTRS)

    1935-01-01

    Interior view of model in 15-Foot Spin Tunnel. Charles Zimmerman wrote in NASA TR No. 557: 'After the observations have been made, the model is lowered into a net held in the air stream by one of the operators or into a large bowl-shaped net at the bottom of the test section. When lowered into the large net, the model is retrieved with a long-handled clamp.' (p. 267) 'The models mused are generally 1/10 to 1/16 scale. The size of the models is limited by the wing span and the wing loading. The maximum allowable span is about 36 inches; the maximum wing loading is about 1.3 pounds per square foot.' (p. 266) 'Balsa wood is the usual structural material because of its low density. It is necessary to hollow out the after portion of the fuselage and to cut out a large portion of the wood in the wings to permit proper mass distribution. The wing cut-outs are covered with silk tissue paper. The leading and trailing edges and tips of the wings are fitted with strips of spruce, pattern pine, or bamboo inset into the edge of the balsa to prevent disfigurement from accidental blows or from striking the safety netting. Lead is used for ballast.' (p. 266)

  5. Full Scale Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Installation of propeller and motor fairing for east exit cone. Smith DeFrance described the propellers and motors in NACA TR No. 459. ' The propellers are located side by side and 48 feet aft of the throat of the exit-cone bell. The propellers are 35 feet 5 inches in diameter and each consists of four cast aluminum alloy blades screwed into a cast steel hub.' 'The most commonly used power plant for operating a wind tunnel is a direct-current motor and motor-generator set with Ward Leonard control system. For the FST it was found that alternating current slip-ring induction motors, together with satisfactory control equipment, could be purchased for approximately 30 percent less than the direct-current equipment. Two 4,000-horsepower slip-ring induction motors with 24 steps of speed between 75 and 300 r.p.m. were therefore installed. In order to obtain the range of speed one pole change was provided and the other variations are obtained by the introduction of resistance in the rotor circuit. This control permits a variation in air speed from 25 to 118 miles per hour. The two motors are connected through an automatic switchboard to one drum-type controller located in the test chamber. All the control equipment is interlocked and connected through time-limit relays, so that regardless of how fast the controller handle is moved the motors will increase in speed at regular intervals.' (p. 294-295)

  6. Tunnelling without barriers

    SciTech Connect

    Lee, K.

    1987-01-01

    The evolution in flat and curved space-time of quantum fields in theories with relative flat potential and its consequences are considered. It is shown that bubble nucleation, a quantum mechanical tunnelling process, may occur in flat space-time, having a bounce solution, even if V(phi) has no barrier. It is shown that bubble nucleation can also occur in curved space-time even though there is no bounce solution in the standard formalism for the bubble nucleation rate in curved space-time. Additionally, bubbles can nucleate during the slow rolling period on the potential in flat and curved space-time, in this case also there is no bounce solution. It is known in the new inflationary scenario that energy density perturbations caused by quantum fluctuations of the scalar field can satisfy the presently observed bounds on density perturbations. Bubble nucleation during the slow rolling period also gives rise to density perturbations. For a model potential density perturbations by bubbles are calculated at the horizon reentering. By applying the bound from the almost isotropic microwave black body radiation on these density perturbations, a constraint on the model potential is obtained. Finally, some further implications on the galaxy formation and applications in more realistic potential are discussed.

  7. 13. Groundwater in urban seashore sediments affected by tunnel constructions

    NASA Astrophysics Data System (ADS)

    Kitterød, Nils-Otto

    2014-05-01

    The purpose of this study was to examine the impact of a planned tunnel construction on the local groundwater level in the archeological deposits at the Old Wharf (Bryggen) of Bergen. The groundwater level is a function of infiltration rates, transmissivity, and boundary conditions. These variables were deduced from available data and supplemented by leakage measurements into the existing Railway tunnel located upstream of the Bryggen area. Previous studies have documented that the pore water in the deposits at Bryggen has different origin (viz fresh precipitation; leakage from drainage systems; infiltration of seawater; infiltration via the bedrock). The catchment of Bryggen is characterized by variable topography (from sea level to about 500 m a.m.s.l.) and steep gradients. Major parts of the catchment have very sparse sediment cover and can be considered as exposed bedrock. The major sediment volumes are deposited close to the sea front. In the upper part of the catchment, the groundwater level in the bedrock is close to the surface. Some observations indicate that boreholes located in lower part of the catchment have artesian pressure, which implies that there is a groundwater flux from the bedrock and into the sediments. Based on this conceptual model, a numerical model was constructed where the seawater was the boundary condition at one side and the groundwater divide on the other side. Transmissivities in the bedrock were deduced from pumping analysis, and steady state infiltration rates was calibrated to give simulated groundwater levels that were consistent to observations. Given these model simplifications, it was possible to calculate a groundwater level in the sediments at Bryggen were all water into the sediments came from the bedrock only. The simulated groundwater level captured roughly the observed groundwater levels. After simulation of the natural groundwater level (i.e. without any artificial extraction of water in the catchment), the impact of

  8. Scanning Tunneling Optical Resonance Microscopy

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila; Wilt, Dave; Raffaelle, Ryne; Gennett, Tom; Tin, Padetha; Lau, Janice; Castro, Stephanie; Jenkins, Philip; Scheiman, Dave

    2003-01-01

    Scanning tunneling optical resonance microscopy (STORM) is a method, now undergoing development, for measuring optoelectronic properties of materials and devices on the nanoscale by means of a combination of (1) traditional scanning tunneling microscopy (STM) with (2) tunable laser spectroscopy. In STORM, an STM tip probing a semiconductor is illuminated with modulated light at a wavelength in the visible-to-near-infrared range and the resulting photoenhancement of the tunneling current is measured as a function of the illuminating wavelength. The photoenhancement of tunneling current occurs when the laser photon energy is sufficient to excite charge carriers into the conduction band of the semiconductor. Figure 1 schematically depicts a proposed STORM apparatus. The light for illuminating the semiconductor specimen at the STM would be generated by a ring laser that would be tunable across the wavelength range of interest. The laser beam would be chopped by an achromatic liquid-crystal modulator. A polarization-maintaining optical fiber would couple the light to the tip/sample junction of a commercial STM. An STM can be operated in one of two modes: constant height or constant current. A STORM apparatus would be operated in the constant-current mode, in which the height of the tip relative to the specimen would be varied in order to keep the tunneling current constant. In this mode, a feedback control circuit adjusts the voltage applied to a piezoelectric actuator in the STM that adjusts the height of the STM tip to keep the tunneling current constant. The exponential relationship between the tunneling current and tip-to-sample distance makes it relatively easy to implement this mode of operation. The choice of method by which the photoenhanced portion of the tunneling current would be measured depends on choice of the frequency at which the input illumination would be modulated (chopped). If the frequency of modulation were low enough (typically < 10 Hz) that the

  9. Overcoming Squeezing in the Yacambú-Quibor Tunnel, Venezuela

    NASA Astrophysics Data System (ADS)

    Hoek, E.; Guevara, R.

    2009-04-01

    The 5 m diameter 23.3 km long Yacambú-Quibor tunnel is designed to carry water through the Andes from the Yacambú dam in the wet tropical Orinoco basin to the semi-arid but fertile Quibor basin in western Venezuela. The tunnel is excavated in silicified and graphitic phyllites at depths of up to 1270 m below surface and extreme squeezing problems have been encountered. Construction involved 8 contracts extending over 32 years with breakthrough being achieved in July 2008. Several excavation methods and various lining designs were used over the years until the adoption of yielding support permitted the Owner and the Contractor to agree that only a circular section would be used and emphasis was placed on developing a routine construction procedure, irrespective of the rock conditions encountered at the face. This paper describes some of the rock engineering issues that were faced during the construction of this tunnel.

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

    USGS Publications Warehouse

    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

  11. Plumbrook Hypersonic Tunnel Facility Graphite Furnace Degradation Mechanisms

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.

    1999-01-01

    A recent rebuild revealed extensive degradation to the large graphite induction furnace in the Hypersonic Tunnel Facility (HTF). This damage to the graphite blocks and insulating felt is examined and modeled with thermochemical equilibrium codes. The primary reactions appear to be with water vapor and the nitrogen purge gas. Based on these conclusions, several changes are recommended. An inert purge gas (e.g. argon or helium) and controlling and monitoring water vapor to about 10 ppm should decrease the damage substantially.

  12. The self streamlining wind tunnel. [wind tunnel walls

    NASA Technical Reports Server (NTRS)

    Goodyer, M. J.

    1975-01-01

    A two dimensional test section in a low speed wind tunnel capable of producing flow conditions free from wall interference is presented. Flexible top and bottom walls, and rigid sidewalls from which models were mounted spanning the tunnel are shown. All walls were unperforated, and the flexible walls were positioned by screw jacks. To eliminate wall interference, the wind tunnel itself supplied the information required in the streamlining process, when run with the model present. Measurements taken at the flexible walls were used by the tunnels computer check wall contours. Suitable adjustments based on streamlining criteria were then suggested by the computer. The streamlining criterion adopted when generating infinite flowfield conditions was a matching of static pressures in the test section at a wall with pressures computed for an imaginary inviscid flowfield passing over the outside of the same wall. Aerodynamic data taken on a cylindrical model operating under high blockage conditions are presented to illustrate the operation of the tunnel in its various modes.

  13. CAVITATION THRESHOLD OF MICROBUBBLES IN GEL TUNNELS BY FOCUSED ULTRASOUND

    PubMed Central

    Sassaroli, E.; Hynynen, K.

    2007-01-01

    The investigation of inertial cavitation in micro-tunnels has significant implications for the development of therapeutic applications of ultrasound such as ultrasound-mediated drug and gene delivery. The threshold for inertial cavitation was investigated using a passive cavitation detector with a center frequency of 1 MHz. Micro-tunnels of various diameters (90 to 800 μm) embedded in gel were fabricated and injected with a solution of Optison™ contrast agent of concentrations 1.2% and 0.2% diluted in water. An ultrasound pulse of duration 500 ms and center frequency 1.736 MHz was used to insonate the microbubbles. The acoustic pressure was increased at one second intervals until broadband noise emission was detected. The pressure threshold at which broadband noise emission was observed was found to be dependent on the diameter of the micro-tunnels, with an average increase of 1.2 to 1.5 between the smallest and the largest tunnels, depending on the microbubble concentration. The evaluation of inertial cavitation in gel tunnels rather than tubes provides a novel opportunity to investigate microbubble collapse in a situation that simulates in vivo blood vessels better than tubes with solid walls do. PMID:17590501

  14. SUBSELENE: a nuclear powered melt tunneling concept for high-speed lunar subsurface transportation tunnels

    SciTech Connect

    Neudecker, J.W. Jr.; Blacic, J.D.; Rowley, J.C.

    1986-01-01

    High-speed lunar surface transportation between manned scientific, commercial, or logistical facilities will require subsurface tunnels because humans must be shielded from Galactic Cosmic Ray and Solar Proton Event irradiations. We present a concept called SUBSELENE in which heat from a nuclear reactor is used to melt rock and form a self-supporting, glass-lined tunnel suitable for Maglev or other high-speed transport modes. We argue that SUBSELENE is an optimal approach to forming transportation tunnels on the Moon because: (1) it uses a high-energy-density, high-efficiency, nuclear power supply; (2) it does not require water or other rare volatiles for upon system muck handling or cooling; (3) it can penetrate through a mechanically varied sequence of rock types without complicated configurational changes; (4) it forms its own support structure as it goes; and (5) it is highly amenable to unmanned, automated operation. We outline the R and D needed to develop a SUBSELENE device and give a cost estimate based on experience with small-scale, field-tested, rock-melting penetrators.

  15. Groundwater Effect on Faulted Rock Mass: An Evaluation of Modi Khola Pressure Tunnel in the Nepal Himalaya

    NASA Astrophysics Data System (ADS)

    Shrestha, Pawan Kumar; Panthi, Krishna Kanta

    2014-05-01

    Groundwater has a negative impact not only in construction activity, but also in stability of a tunnel. Severity increases particularly in tunnels passing through fault gouge and breccia, where rock material is completely crushed and extremely weak. Instantaneous collapse and excessive plastic deformation is most likely in tunnels passing through such zones. Often, `flowing' conditions may prevail if groundwater is mixed in the rock mass. This paper presents one such tunnel case in the Nepal Himalaya; i.e. the Modi pressure tunnel. This pressure tunnel passes through a tectonic fault consisting of gouge material. High deformation in the tunnel was observed while excavating the tunnel through the fault. Based on the tunnel deformation that was actually measured, the paper first back-calculates the rock mass strength by analytical approach. Then, the extent of in-situ stress condition in the area is determined by numerical modeling for the rock mass with no ground water in consideration. The ground water effect is then analyzed. We found that the effect of ground water with a static head <1.5 bar pressure may increase the deformation by up to a maximum of 30 %. Finally, we briefly discuss uncertainties related to the input parameter study and used methodologies.

  16. National Wind Tunnel Complex (NWTC)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The National Wind Tunnel Complex (NWTC) Final Report summarizes the work carried out by a unique Government/Industry partnership during the period of June 1994 through May 1996. The objective of this partnership was to plan, design, build and activate 'world class' wind tunnel facilities for the development of future-generation commercial and military aircraft. The basis of this effort was a set of performance goals defined by the National Facilities Study (NFS) Task Group on Aeronautical Research and Development Facilities which established two critical measures of improved wind tunnel performance; namely, higher Reynolds number capability and greater productivity. Initial activities focused upon two high-performance tunnels (low-speed and transonic). This effort was later descoped to a single multipurpose tunnel. Beginning in June 1994, the NWTC Project Office defined specific performance requirements, planned site evaluation activities, performed a series of technical/cost trade studies, and completed preliminary engineering to support a proposed conceptual design. Due to budget uncertainties within the Federal government, the NWTC project office was directed to conduct an orderly closure following the Systems Design Review in March 1996. This report provides a top-level status of the project at that time. Additional details of all work performed have been archived and are available for future reference.

  17. New Spray Bar System Installed in NASA Lewis' Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Irvine, Thomas B.

    1998-01-01

    NASA Lewis Research Center's Icing Research Tunnel (IRT) is the world's largest refrigerated wind tunnel dedicated to the study of aircraft icing. In the IRT, natural icing conditions are duplicated to test the effects of in-flight icing on actual aircraft components and on scale models of airplanes and helicopters. The IRT's ability to reproduce a natural icing cloud was significantly improved with the recent installation of a new spray bar system. It is the spray bar system that transforms the low-speed wind tunnel into an icing wind tunnel by producing microscopic droplets of water and injecting them into the wind tunnel air stream in order to accurately simulate cloud moisture.

  18. Other Cryogenic Wind Tunnel Projects

    NASA Technical Reports Server (NTRS)

    Kilgore, Robert A.

    1997-01-01

    The first cryogenic tunnel was built at the NASA Langley Research Center in 1972. Since then, many cryogenic wind-tunnels have been built at aeronautical research centers around the world. In this lecture some of the more interesting and significant of these projects that have not been covered by other lecturers at this Special Course are described. In this lecture authors describe cryogenic wind-tunnel projects at research centers in four countries: China (Chinese Aeronautical Research and Development Center); England (College of Aeronautics at Cranfield, and Defence Research Agency - Bedford); Japan (National Aerospace Laboratory, University of Tsukuba, and National Defense Academy); and United States (Douglas Aircraft Co., University of Illinois at Urbana-Champaign, and NASA Langley).

  19. Other cryogenic wind tunnel projects

    NASA Technical Reports Server (NTRS)

    Kilgore, Robert A.

    1989-01-01

    The first cryogenic tunnel was built in 1972. Since then, many cryogenic wind-tunnel projects were started at aeronautical research centers around the world. Some of the more significant of these projects are described which are not covered by other lecturers at this Special Course. Described are cryogenic wind-tunnel projects in five countries: China (Chinese Aeronautical Research and Development Center); England (College of Aeronautics at Cranfield, and Royal Aerospace Establishment-Bedford); Japan (National Aerospace Laboratory, University of Tsukuba, and National Defense Academy); United States (Douglas Aircraft Co., University of Illinois at Urbana-Champaign and NASA Langley); and U.S.S.R. (Central Aero-Hydronamics Institute (TsAGI), Institute of Theoretical and Applied Mechanics (ITAM), and Physical-Mechanical Institute at Kharkov (PMI-K).

  20. The Langley Annular Transonic Tunnel

    NASA Technical Reports Server (NTRS)

    Habel, Louis W; Henderson, James H; Miller, Mason F

    1952-01-01

    Report describes the development of the Langley annular transonic tunnel, a facility in which test Mach numbers from 0.6 to slightly over 1.0 are achieved by rotating the test model in an annular passage between two concentric cylinders. Data obtained for two-dimensional airfoil models in the Langley annular transonic tunnel at subsonic and sonic speeds are shown to be in reasonable agreement with experimental data from other sources and with theory when comparisons are made for nonlifting conditions or for equal normal-force coefficients rather than for equal angles of attack. The trends of pressure distributions obtained from measurements in the Langley annular transonic tunnel are consistent with distributions calculated for Prandtl-Meyer flow.

  1. Interim geological investigations in the U12e.04 tunnel, Nevada Test Site, Nye County, Nevada

    USGS Publications Warehouse

    Emerick, W.L.; Dickey, D.D.; McKeown, F.A.

    1962-01-01

    The Ul2e.04 tunnel is a part of the Ul2e tunnel system, which has been driven southwestward beneath Rainier Mesa in the northern part of the Nevada Test Site. The Ul2e.04 tunnel was driven about S. 15? W. in zeolitic tuff of subunits E and F of Tunnel Bed W near the top of the lower member of the Indian Trail Formation (upper Miocene or lower Pliocene). Dolomite of Paleozoic age lies about 915 feet below the end of the tunnel; vertical cover over the end of the tunnel to the surface of Rainier Mesa is about 1,390 feet. The tuffs in the tunnel strike almost north-south and dip to the west. There are several normal northwest-trending faults with vertical to steep dips and small displacements. The predominant joint set strikes northwest and dips mostly vertically or steeply to the northeast. Petrographically and chemically the tuffs in the U12e.04 tunnel are similar to other tuffs of the Indian Trail Formation from the Nevada Test Site, The tuffs in the tunnel have an average porosity of 38.6 percent, dry bulk density of 1.46 g/cc (grams per cubic centimeter), grain density of 2.38 g/cc, water content of 20.7 percent by weight. Shore hardness of 25.1, and unconfined compressive strength of 4,400 psi (pounds per square inch). Separately, the tuffs from the chamber at the end of the tunnel have an average porosity of 36.8 percent, dry bulk density of 1.51 g/cc, grain density of 2.38 g/cc, water content of 20.0 percent by weight, Shore hardness of 27.2 and unconfined compressive strength of 4,500 psi. An NX-size cored hole was drilled from the surface of Rainier Mesa into the Ul2e.04 chamber.

  2. Carpal Tunnel Exercises: Can They Relieve Symptoms?

    MedlinePlus

    ... other carpal tunnel treatments, such as surgery, behavior modification or wrist splints. Carpal tunnel syndrome is caused ... when combined with other treatments, such as activity modification, wrist splinting or corticosteroid injections. After surgery to ...

  3. Computational multiqubit tunnelling in programmable quantum annealers

    PubMed Central

    Boixo, Sergio; Smelyanskiy, Vadim N.; Shabani, Alireza; Isakov, Sergei V.; Dykman, Mark; Denchev, Vasil S.; Amin, Mohammad H.; Smirnov, Anatoly Yu; Mohseni, Masoud; Neven, Hartmut

    2016-01-01

    Quantum tunnelling is a phenomenon in which a quantum state traverses energy barriers higher than the energy of the state itself. Quantum tunnelling has been hypothesized as an advantageous physical resource for optimization in quantum annealing. However, computational multiqubit tunnelling has not yet been observed, and a theory of co-tunnelling under high- and low-frequency noises is lacking. Here we show that 8-qubit tunnelling plays a computational role in a currently available programmable quantum annealer. We devise a probe for tunnelling, a computational primitive where classical paths are trapped in a false minimum. In support of the design of quantum annealers we develop a nonperturbative theory of open quantum dynamics under realistic noise characteristics. This theory accurately predicts the rate of many-body dissipative quantum tunnelling subject to the polaron effect. Furthermore, we experimentally demonstrate that quantum tunnelling outperforms thermal hopping along classical paths for problems with up to 200 qubits containing the computational primitive. PMID:26739797

  4. Tunnel Cost-Estimating Methods.

    DTIC Science & Technology

    1981-10-01

    consists of crushed rock or soft ground and the remainder is more competent rock. Forepoling or spiLing is used to support the roof between the nearest steel ...set and the face. Sharpened wood spiles or steel rods are driven into the roof at a shallow angle from behind the nearest support and ex- tended some...loading and hauling. Tunnels driven with a shield 17. Shield-driven tunnels get their name from a steel plate shaped to fit the outside dimensions of the

  5. Enhanced tunneling through nonstationary barriers

    SciTech Connect

    Palomares-Baez, J. P.; Rodriguez-Lopez, J. L.; Ivlev, B.

    2007-11-15

    Quantum tunneling through a nonstationary barrier is studied analytically and by a direct numerical solution of Schroedinger equation. Both methods are in agreement and say that the main features of the phenomenon can be described in terms of classical trajectories which are solutions of Newton's equation in complex time. The probability of tunneling is governed by analytical properties of a time-dependent perturbation and the classical trajectory in the plane of complex time. Some preliminary numerical calculations of Euclidean resonance (an easy penetration through a classical nonstationary barrier due to an underbarrier interference) are presented.

  6. Application of quality assurance controls to TBM tunneling on the Yucca Mountain Project

    SciTech Connect

    Christensen, J.D.

    1996-06-01

    As part of the Yucca Mountain Project (YMP), a 7.62-meter diameter tunnel is being constructed using a Tunnel Boring Machine (TBM). This tunnel, which may form a portion of a permanent high-level nuclear waste repository, is being constructed under the auspices of a nuclear quality assurance (QA) program. The YMP nuclear QA program applies to items and activities determined to be important to radiological safety, waste isolation, and potential interactions with the environment. The items and activities determined to be important have been assigned a quality assurance classification. This paper focuses on the items (rockbolts, steel sets, and shotcrete) and quality affecting activities involved in providing ground support and excavating the tunnel. Typical activities that have been assigned QA classifications include TBM maintenance, control of water used in the tunnel during construction, and control of diesel emissions in the tunnel. The paper concludes that the key to the successful implementation of nuclear QA requirements for tunneling at Yucca Mountain was the assignment of personnel with the appropriate mix of tunneling and nuclear experience.

  7. Resonance tunneling spectroscopy of heteropoly compounds

    SciTech Connect

    Dalidchik, F. I. Budanov, B. A.; Kolchenko, N. N.; Balashov, E. M.; Kovalevskii, S. A.

    2012-12-15

    The electron tunneling spectra of phosphomolybdic and phosphomolybdovanadic acids have been measured using a scanning tunneling microscope. A new mechanism of negative differential resistance (NDR) formation in tunneling nanocontacts is established, which is general for all systems featuring the Wannier-Stark localization effect. A two-center inelastic resonance tunneling model is constructed, which allows the values of both electron and vibrational energy parameters to be determined from the measured spectra.

  8. A Wind Tunnel Captive Aircraft Testing Technique

    DTIC Science & Technology

    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

  9. 78 FR 46117 - National Tunnel Inspection Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-30

    ... a significant loss of productivity and have severe financial impacts on a large region of the.... Numerous domestic and international incidents demonstrate that tunnel fires often result in a large number... consistency in the tunnel inspection techniques used by the various tunnel owners, implementing NTIS...

  10. 43 CFR 3832.40 - Tunnel sites.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Tunnel sites. 3832.40 Section 3832.40 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.40 Tunnel...

  11. 43 CFR 3832.40 - Tunnel sites.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Tunnel sites. 3832.40 Section 3832.40 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.40 Tunnel...

  12. 43 CFR 3832.40 - Tunnel sites.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Tunnel sites. 3832.40 Section 3832.40 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.40 Tunnel...

  13. 43 CFR 3832.40 - Tunnel sites.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Tunnel sites. 3832.40 Section 3832.40 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.40 Tunnel...

  14. Hydrochemistry of urban groundwater, Seoul, Korea: the impact of subway tunnels on groundwater quality.

    PubMed

    Chae, Gi-Tak; Yun, Seong-Taek; Choi, Byoung-Young; Yu, Soon-Young; Jo, Ho-Young; Mayer, Bernhard; Kim, Yun-Jong; Lee, Jin-Yong

    2008-10-23

    Hydrogeologic and hydrochemical data for subway tunnel seepage waters in Seoul (Republic of Korea) were examined to understand the effect of underground tunnels on the degradation of urban groundwater. A very large quantity of groundwater (up to 63 million m3 year(-1)) is discharged into subway tunnels with a total length of 287 km, resulting in a significant drop of the local groundwater table and the abandonment of groundwater wells. For the tunnel seepage water samples (n = 72) collected from 43 subway stations, at least one parameter among pathogenic microbes (total coliform, heterotrophic bacteria), dissolved Mn and Fe, NH4+, NO3(-), turbidity, and color exceeded the Korean Drinking Water Standards. Locally, tunnel seepage water was enriched in dissolved Mn (avg. 0.70 mg L(-1), max. 5.58 mg L(-1)), in addition to dissolved Fe, NH4+, and pathogenic microbes, likely due to significant inflow of sewage water from broken or leaking sewer pipes. Geochemical modeling of redox reactions was conducted to simulate the characteristic hydrochemistry of subway tunnel seepage. The results show that variations in the reducing conditions occur in urban groundwater, dependent upon the amount of organic matter-rich municipal sewage contaminating the aquifer. The organic matter facilitates the reduction and dissolution of Mn- and Fe-bearing solids in aquifers and/or tunnel construction materials, resulting in the successive increase of dissolved Mn and Fe. The present study clearly demonstrates that locally significant deterioration of urban groundwater is caused by a series of interlinked hydrogeologic and hydrochemical changes induced by underground tunnels.

  15. Macroscopic quantum tunneling in Josephson tunnel junctions and Coulomb blockade in single small tunnel junctions

    SciTech Connect

    Cleland, A.N.

    1991-04-01

    Experiments investigating the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very small capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters; the tunneling rate in the moderately damped (Q {approx} 1) junction is seen to be reduced by a factor of 300 from that predicted for an undamped junction. The phase is seen to be a good quantum-mechanical variable. The experiments on small capacitance tunnel junctions extend the measurements on the larger-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wavefunction has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias. I present the first clear observation of the Coulomb blockade in single junctions. The electrical environment of the tunnel junction, however, strongly affects the behavior of the junction: higher resistance leads are observed to greatly sharpen the Coulomb blockade over that seen with lower resistance leads. I present theoretical descriptions of how the environment influences the junctions; comparisons with the experimental results are in reasonable agreement.

  16. Morphological properties of tunnel valleys beneath the southern sector of the former Laurentide Ice Sheet

    NASA Astrophysics Data System (ADS)

    Livingstone, Stephen; Clark, Chris

    2016-04-01

    Tunnel valleys have been widely reported on the bed of former ice sheets and are considered an important expression of subglacial meltwater drainage. Although known to have been cut by erosive meltwater flow, the water source and development of channels has been widely debated. Possible mechanisms include: (i) gradual formation by water flow in a subglacially deforming bed into channels under steady-state conditions; (ii) time-transgressive formation close to the ice margin by drainage of supraglacial meltwater to the bed or of meltwater temporarily impounded behind a permafrost wedge; and or (iii) by catastrophic subglacial meltwater floods. We have mapped and analysed the spatial pattern and morphometry of tunnel valleys and associated glacial bedforms along the southern sector of the former Laurentide Ice Sheet from high-resolution digital elevation models. Around 2000 tunnel valleys have been mapped, revealing a well-organised pattern of sub-parallel, semi-regularly spaced valleys that cluster together in distinctive networks. The tunnel valleys are typically <20 km long, and 0.5-3 km wide and preferentially terminate at moraines. They tend to be associated with outwash fans, eskers, glacial curvilineations, giant current ripples, and hill-hole-pairs. A relative age of the tunnel valleys, based on cross-cutting relationships, is used to resolve when individual tunnel valleys and networks were eroded. Our results suggest a time-transgressive origin for most tunnel valleys (i.e. they grow upstream) with some contributions from large meltwater drainage events.

  17. Videometric applications in wind tunnels

    NASA Astrophysics Data System (ADS)

    Burner, Alpheus W.; Radeztsky, Ron H.; Liu, Tianshu

    1997-07-01

    Videometric measurements in wind tunnels can be very challenging due to the limited optical access, model dynamics, optical path variability during testing, large range of temperature and pressure, hostile environment, and the requirements for high productivity and large amounts of data on a daily basis. Other complications for wind tunnel testing include the model support mechanism and stringent surface finish requirements for the models in order to maintain aerodynamic fidelity. For these reasons nontraditional photogrammetric techniques and procedures sometimes must be employed. In this paper several such applications are discussed for wind tunnels which include test conditions with Mach numbers from low speed to hypersonic, pressures from less than an atmosphere to nearly seven atmospheres, and temperatures from cryogenic to above room temperature. Several of the wind tunnel facilities are continuous flow while one is a short duration blow-down facility. Videometric techniques and calibration procedures developed to measure angle of attack, the change in wing twist and bending induced by aerodynamic load, and the effects of varying model injection rates are described. Some advantages and disadvantages of these techniques are given and comparisons are made with non-optical and more traditional video photogrammetric techniques.

  18. Aorta-Right Atrial Tunnel

    PubMed Central

    Krishna, Cheemalapati Sai; Baruah, Dibya Kumar; Reddy, Gangireddy Venkateswara; Panigrahi, Nanda Kishore; Suman, Kalagara; Kumar, Palli Venkata Naresh

    2010-01-01

    Aorta–right atrial tunnel is a vascular channel that originates from one of the sinuses of Valsalva and terminates in either the superior vena cava or the right atrium. The tunnel is classified as anterior or posterior, depending upon its course in relation to the ascending aorta. An origin above the sinotubular ridge differentiates the tunnel from an aneurysm of the sinus of Valsalva, and the absence of myocardial branches differentiates it from a coronary–cameral fistula. Clinical presentation ranges from an asymptomatic precordial murmur to congestive heart failure. The embryologic background and pathogenesis of this lesion are attributable either to an aneurysmal dilation of the sinus nodal artery or to a congenital weakness of the aortic media. In either circumstance, progressive enlargement of the tunnel and ultimate rupture into the low-pressure right atrium could occur under the influence of the systemic pressure. The lesion is diagnosed by use of 2-dimensional echocardiography and cardiac catheterization. Computed tomographic angiography is an additional noninvasive diagnostic tool. The possibility of complications necessitates early therapy, even in asymptomatic patients or those with a hemodynamically insignificant shunt. Available treatments are catheter-based intervention, external ligation under controlled hypotension, or surgical closure with the patient under cardiopulmonary bypass. Herein, we discuss the cases of 2 patients who had this unusual anomaly. We highlight the outcome on follow-up imaging (patient 1) and the identification and safe reimplantation of the coronary artery (patient 2). PMID:20844628

  19. Mars Surface Tunnel Element Concept

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle A.; Mary, Natalie; Howe, A. Scott; Jeffries, Sharon

    2016-01-01

    How Mars surface crews get into their ascent vehicle has profound implications for Mars surface architecture. To meet planetary protection protocols, the architecture has get Intravehicular Activity (IVA)-suited crew into a Mars Ascent Vehicle (MAV) without having to step outside into the Mars environment. Pushing EVA suit don/doff and EVA operations to an element that remains on the surface also helps to minimize MAV cabin volume, which in turn can reduce MAV cabin mass. Because the MAV will require at least seven kilograms of propellant to ascend each kilogram of cabin mass, minimal MAV mass is desired. For architectures involving more than one surface element-such as an ascent vehicle and a pressurized rover or surface habitat-a retractable tunnel is an attractive solution. Beyond addressing the immediate MAV access issue, a reusable tunnel may be useful for other surface applications once its primary mission is complete. A National Aeronautics and Space Administration (NASA) team is studying the optimal balance between surface tunnel functionality, mass, and stowed volume as part of the Evolvable Mars Campaign (EMC). The "Minimum Functional Tunnel" is a conceptual design that performs a single function. Having established this baseline configuration, the next step is to trade design options, evaluate other applications, and explore alternative solutions.

  20. A Seamless Ubiquitous Telehealthcare Tunnel

    PubMed Central

    Cheng, Po-Hsun; Lin, Bor-Shing; Yu, Chu; Hu, Shun-Hsiang; Chen, Sao-Jie

    2013-01-01

    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. PMID:23917812

  1. Spinoff from Wind Tunnel Technology

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Douglas Juanarena, a former NASA Langley instrument design engineer, found a solution to the problem of long, repetitive tunnel runs needed to measure airflow pressures. Electronically scanned pressure (ESP) replaced mechanical systems with electronic sensors. Juanarena licensed the NASA-patented technology and now manufactures ESP modules for research centers, aerospace companies, etc.

  2. Micromachined electron tunneling infrared sensors

    NASA Technical Reports Server (NTRS)

    Kenny, T. W.; Kaiser, W. J.; Podosek, J. A.; Rockstad, H. K.; Reynolds, J. K.

    1993-01-01

    The development of an improved Golay cell is reported. This new sensor is constructed entirely from micromachined silicon components. A silicon oxynitride (SiO(x)N(y)) membrane is deflected by the thermal expansion of a small volume of trapped gas. To detect the motion of the membrane, an electron tunneling transducer is used. This sensor detects electrons which tunnel through the classically forbidden barrier between a tip and a surface; the electron current is exponentially dependent on the separation between the tip and the surface. The sensitivity of tunneling transducers constructed was typically better than 10(exp -3) A/square root of Hz. Through use of the electron tunneling transducer, the scaling laws which have prevented the miniaturization of the Golay cell are avoided. This detector potentially offers low cost fabrication, compatibility with silicon readout electronics, and operation without cooling. Most importantly, this detector may offer better sensitivity than any other uncooled infrared sensor, with the exception of the original Golay cell.

  3. A seamless ubiquitous telehealthcare tunnel.

    PubMed

    Cheng, Po-Hsun; Lin, Bor-Shing; Yu, Chu; Hu, Shun-Hsiang; Chen, Sao-Jie

    2013-08-02

    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.

  4. Aorta-right atrial tunnel.

    PubMed

    Sai Krishna, Cheemalapati; Baruah, Dibya Kumar; Reddy, Gangireddy Venkateswara; Panigrahi, Nanda Kishore; Suman, Kalagara; Kumar, Palli Venkata Naresh

    2010-01-01

    Aorta-right atrial tunnel is a vascular channel that originates from one of the sinuses of Valsalva and terminates in either the superior vena cava or the right atrium. The tunnel is classified as anterior or posterior, depending upon its course in relation to the ascending aorta. An origin above the sinotubular ridge differentiates the tunnel from an aneurysm of the sinus of Valsalva, and the absence of myocardial branches differentiates it from a coronary-cameral fistula. Clinical presentation ranges from an asymptomatic precordial murmur to congestive heart failure. The embryologic background and pathogenesis of this lesion are attributable either to an aneurysmal dilation of the sinus nodal artery or to a congenital weakness of the aortic media. In either circumstance, progressive enlargement of the tunnel and ultimate rupture into the low-pressure right atrium could occur under the influence of the systemic pressure.The lesion is diagnosed by use of 2-dimensional echocardiography and cardiac catheterization. Computed tomographic angiography is an additional noninvasive diagnostic tool. The possibility of complications necessitates early therapy, even in asymptomatic patients or those with a hemodynamically insignificant shunt. Available treatments are catheter-based intervention, external ligation under controlled hypotension, or surgical closure with the patient under cardiopulmonary bypass.Herein, we discuss the cases of 2 patients who had this unusual anomaly. We highlight the outcome on follow-up imaging (patient 1) and the identification and safe reimplantation of the coronary artery (patient 2).

  5. Videometric Applications in Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Radeztsky, R. H.; Liu, Tian-Shu

    1997-01-01

    Videometric measurements in wind tunnels can be very challenging due to the limited optical access, model dynamics, optical path variability during testing, large range of temperature and pressure, hostile environment, and the requirements for high productivity and large amounts of data on a daily basis. Other complications for wind tunnel testing include the model support mechanism and stringent surface finish requirements for the models in order to maintain aerodynamic fidelity. For these reasons nontraditional photogrammetric techniques and procedures sometimes must be employed. In this paper several such applications are discussed for wind tunnels which include test conditions with Mach number from low speed to hypersonic, pressures from less than an atmosphere to nearly seven atmospheres, and temperatures from cryogenic to above room temperature. Several of the wind tunnel facilities are continuous flow while one is a short duration blowdown facility. Videometric techniques and calibration procedures developed to measure angle of attack, the change in wing twist and bending induced by aerodynamic load, and the effects of varying model injection rates are described. Some advantages and disadvantages of these techniques are given and comparisons are made with non-optical and more traditional video photogrammetric techniques.

  6. Tunnel Vision in Environmental Management.

    ERIC Educational Resources Information Center

    Miller, Alan

    1982-01-01

    Discusses problem-solving styles in environmental management and the specific deficiencies in these styles that might be grouped under the label "tunnel vision," a form of selective attention contributing to inadequate problem-formulation, partial solutions to complex problems, and generation of additional problems. Includes educational…

  7. Scale Model Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Canacci, Victor A.

    1997-01-01

    NASA Lewis Research Center's Icing Research Tunnel (IRT) is the world's largest refrigerated wind tunnel and one of only three icing wind tunnel facilities in the United States. The IRT was constructed in the 1940's and has been operated continually since it was built. In this facility, natural icing conditions are duplicated to test the effects of inflight icing on actual aircraft components as well as on models of airplanes and helicopters. IRT tests have been used successfully to reduce flight test hours for the certification of ice-detection instrumentation and ice protection systems. To ensure that the IRT will remain the world's premier icing facility well into the next century, Lewis is making some renovations and is planning others. These improvements include modernizing the control room, replacing the fan blades with new ones to increase the test section maximum velocity to 430 mph, installing new spray bars to increase the size and uniformity of the artificial icing cloud, and replacing the facility heat exchanger. Most of the improvements will have a first-order effect on the IRT's airflow quality. To help us understand these effects and evaluate potential improvements to the flow characteristics of the IRT, we built a modular 1/10th-scale aerodynamic model of the facility. This closed-loop scale-model pilot tunnel was fabricated onsite in the various shops of Lewis' Fabrication Support Division. The tunnel's rectangular sections are composed of acrylic walls supported by an aluminum angle framework. Its turning vanes are made of tubing machined to the contour of the IRT turning vanes. The fan leg of the tunnel, which transitions from rectangular to circular and back to rectangular cross sections, is fabricated of fiberglass sections. The contraction section of the tunnel is constructed from sheet aluminum. A 12-bladed aluminum fan is coupled to a turbine powered by high-pressure air capable of driving the maximum test section velocity to 550 ft

  8. Dirac particle tunneling from black rings

    SciTech Connect

    Jiang Qingquan

    2008-08-15

    Recent research shows that Hawking radiation can be treated as a quantum tunneling process, and Hawking temperatures of Dirac particles across the horizon of a black hole can be correctly recovered via the fermion tunneling method. In this paper, motivated by the fermion tunneling method, we attempt to apply the analysis to derive Hawking radiation of Dirac particles via tunneling from black ring solutions of 5-dimensional Einstein-Maxwell-dilaton gravity theory. Finally, it is interesting to find that, as in the black hole case, fermion tunneling can also result in correct Hawking temperatures for the rotating neutral, dipole, and charged black rings.

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

    NASA Technical Reports Server (NTRS)

    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.

  10. San Antonio River Tunnel and Shafts Foundation Report

    DTIC Science & Technology

    1993-10-01

    Alignment 7 a. Overburden 7 b. Primary Formations 8 S c. Geologic Structure 10 d. Formation Weathering 11 e. Ground Water 12 f. Seismicity 13 g. Engineering...from the city, and transfer the water beneath the city to an outlet shaft downstream. San Pedro Creek Tunnel extends 5,985 feet from the center of the...liner with an I.D. of 24 feet 4 inches. An 18-foot I.D. cast-in-place concrete maintenance shaft was constructed at two sites; one on Water 0 Street

  11. Moisture Observations in Sealed Tunnels at Yucca Mountain, Nevada

    NASA Astrophysics Data System (ADS)

    Coleman, N. M.; Winterle, J.; Arlt, H.; Dinwiddie, C.; Fedors, R.

    2002-12-01

    The Topopah Spring Tuff is the host rock for a proposed repository for high-level nuclear waste. Underground tunnels and alcoves in this tuff that have been sealed from ventilation provide potentially useful data on natural moisture conditions and can help address the question of whether significant amounts of percolating groundwater drip into tunnels under present-day conditions. Given the low infiltration rates in the region, natural seepage and dripping in the sealed tunnels would provide evidence of focused flow within fracture networks that could be used to help calibrate seepage models for present-day conditions. These observations can then be used to estimate seepage fluxes during future, wetter climates. In 1999 the Department of Energy (DOE) sealed a nearly 1-km long tunnel bored near the proposed repository area. Four bulkheads isolate four sections of this tunnel, commonly called the Cross Drift, to allow a return to natural, ambient moisture conditions. Alcove 7, which crosses the Ghost Dance Fault, is a niche that has also been sealed with a bulkhead. Observations made in the sealed tunnels under unventilated conditions help to ensure that moisture observations will be little affected by the rapid drying effects of ventilation. Evidence of humid conditions has been seen during such unventilated entries, including small puddles apparently produced by condensation dripping. DOE is attempting to systematically collect drips in sample bottles and in plastic sheets so that chemical analyses can be used to identify sources of the water (i.e., natural seepage, condensation, or a mixture). To date two locations of possible natural seepage have been observed: one in Alcove 7 and the other in a sealed section of the Cross Drift. Both of these drip zones occur outside the proposed repository footprint. DOE is continuing work in the sealed drifts to address agreements with NRC. Hydrologic data from the sealed tunnels provide a reference point for DOE's performance

  12. 2. 'Tunnel No 6 West End, Front Elevation, Sectional Elevation ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. 'Tunnel No 6 West End, Front Elevation, Sectional Elevation on Centerline of Portal,' Southern Pacific Standard Single-Track Tunnel, 1910. Tunnel 6, which today would be Tunnel 20, was daylighted and no longer exists. Compare to photos in documentation sets for Tunnel 23 (HAER No. CA-198), Tunnel 24 (HAER No. CA-200), Tunnel 25 (HAER No. CA-201), Tunnel 27 (HAER No. CA-203), Tunnel 28 (HAER No. CA-204), and Tunnel 29 (HAER No. CA-205). - Central Pacific Transcontinental Railroad, Sacramento to Nevada state line, Sacramento, Sacramento County, CA

  13. A system to measure flow moisture content in hypersonic wind tunnels

    NASA Technical Reports Server (NTRS)

    West, James W.

    1992-01-01

    The technique and equipment is described which is used for obtaining data on the moisture content in two NASA Langley Hypersonic Wind Tunnels. A detailed description of the sampling system and its operation is presented along with the moisture analyzer used. The procedure used for converting dew point to parts of water per million by volume (ppmv) is included with graphs that show tunnel moisture content at various pressures.

  14. Remark on massive particle's de Sitter tunneling

    SciTech Connect

    Jiang, Qing-Quan; Chen, De-You; Wen, Dan E-mail: deyouchen@126.com

    2013-11-01

    In the work [J. Y. Zhang and Z. Zhao, Massive particles's black hole tunneling and de Sitter tunneling, Nucl. Phys. B 725 (2005) 173.], the Hawking radiation of the massive particle via tunneling from the de Sitter cosmological horizon has been first described in the tunneling framework. However, the geodesic equation of the massive particle was unnaturally and awkwardly defined there by investigating the relation between the group and phase velocity. In this paper, we start from the Lagrangian analysis on the action to naturally produce the geodesic equation of the tunneling massive particle. Then, based on the new definition for the geodesic equation, we revisit the Hawking radiation of the massive particle via tunneling from the de Sitter cosmological horizon. It is noteworthy that, the highlight of our work is a new and important development of the Parikh-Wilczek's tunneling method, which can make it more physical.

  15. On the formation of the tunnel valleys of the Superior lobe, central Minnesota

    NASA Astrophysics Data System (ADS)

    Moores, Howard D.

    1989-07-01

    When considering the formation of tunnel valleys, most researchers have appealed to basal melting as the primary source of water. Erosion of the tunnel valleys can then be accomplished by steady-state drainage over a long period or by storage and subsequent catastrophic release. However, field relationships in a large system of tunnel valleys formed by the Superior lobe in central Minnesota indicate that another source of water must be considered. The Minnesota tunnel valleys are composed of individual segments 10-20 km long, and the segments commonly terminate in subaerial outwash fans at recessional ice margin positions. Eskers, associated with the tunnel valleys, are also composed of short segments, frequently beginning at moulin kames and terminating at the head of outwash fans. The dominant source of the water responsible for tunnel-valley formation was seasonal meltwater from the glacier surface that reached the bed through moulins and crevasses. The apparent continuity of the valleys resulted from the headward development of the englacial drainage system during ice retreat.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Tunneling magnetoresistance in Si nanowires

    NASA Astrophysics Data System (ADS)

    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.

  18. Single-contact tunneling thermometry

    DOEpatents

    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.

  19. Tunneling decay of false kinks

    NASA Astrophysics Data System (ADS)

    Dupuis, Éric; Gobeil, Yan; MacKenzie, Richard; Marleau, Luc; Paranjape, M. B.; Ung, Yvan

    2015-07-01

    We consider the decay of "false kinks," that is, kinks formed in a scalar field theory with a pair of degenerate symmetry-breaking false vacua in 1 +1 dimensions. The true vacuum is symmetric. A second scalar field and a peculiar potential are added in order for the kink to be classically stable. We find an expression for the decay rate of a false kink. As with any tunneling event, the rate is proportional to exp (-SE) where SE is the Euclidean action of the bounce describing the tunneling event. This factor varies wildly depending on the parameters of the model. Of interest is the fact that for certain parameters SE can get arbitrarily small, implying that the kink is only barely stable. Thus, while the false vacuum itself may be very long-lived, the presence of kinks can give rise to rapid vacuum decay.

  20. Tunneling of heat between metals

    NASA Astrophysics Data System (ADS)

    Mahan, G. D.

    2017-03-01

    We provide a theory of how heat tunnels between two parallel metal surfaces separated by an air gap. Two contributions are calculated: (1) electron-electron interactions and (2) photon fields from surface plasmons. Both contributions can transfer energy through low energy electron pairs. Our concern is with heat flow for small air gaps, on the order of nanometers. In that case the contribution from electron-electron interactions is most important. The contribution from photons is more important at larger separations.

  1. Observing remnants by fermions' tunneling

    SciTech Connect

    Chen, D.Y.; Wu, H.W.; Yang, H. E-mail: iverwu@uestc.edu.cn

    2014-03-01

    The standard Hawking formula predicts the complete evaporation of black holes. In this paper, we introduce effects of quantum gravity into fermions' tunneling from Reissner-Nordstrom and Kerr black holes. The quantum gravity effects slow down the increase of Hawking temperatures. This property naturally leads to a residue mass in black hole evaporation. The corrected temperatures are affected by the quantum numbers of emitted fermions. Meanwhile, the temperature of the Kerr black hole is a function of θ due to the rotation.

  2. Full-Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Full-Scale Tunnel (FST). Construction of balance housing. Smith DeFrance noted the need for this housing in his NACA TR No. 459: 'The entire floating frame and scale assembly is enclosed in a room for protection from air currents and the supporting struts are shielded by streamlined fairings which are secured to the roof of the balance room and free from the balance.'

  3. Neurolysis for failed tarsal tunnel surgery.

    PubMed

    Yalcinkaya, Merter; Ozer, Utku Erdem; Yalcin, M Burak; Bagatur, A Erdem

    2014-01-01

    The purpose of the present study was to investigate the causes of failure after tarsal tunnel release and the operative findings in the secondary interventions and the outcomes. The data from 8 patients who had undergone revision surgery for failed tarsal tunnel release at least 12 months earlier were evaluated retrospectively. Only the patients with idiopathic tarsal tunnel syndrome were included, and all had unilateral symptoms. Neurophysiologic tests confirmed the clinical diagnosis of failed tarsal tunnel release in all patients. Magnetic resonance imaging revealed varicose veins within the tarsal tunnel in 1 patient (12.5%) and tenosynovitis in another (12.5%). Open tarsal tunnel release was performed in all patients, and the tibialis posterior nerve, medial and lateral plantar nerves (including the first branch of the lateral plantar nerve), and medial calcaneal nerve were released in their respective tunnels, and the septum between the tunnels was resected. The outcomes were assessed according to subjective patient satisfaction as excellent, good, fair, or poor. During revision surgery, insufficient release of the tarsal tunnel, especially distally, was observed in all the patients, and fibrosis of the tibialis posterior nerve was present in 1 (12.5%). The outcomes according to subjective patient satisfaction were excellent in 5 (62.5%), good in 2 (25%), and fair in 1 (12.5%). The fair outcome was obtained in the patient with fibrosis of the nerve. Insufficient release of the tarsal tunnel was the main cause of failed tarsal tunnel release. Releasing the 4 distinct tunnels and permitting immediate mobilization provided satisfactory results in patients with failed tarsal tunnel release.

  4. Water

    USGS Publications Warehouse

    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.

  5. Tunneling decay of false vortices

    NASA Astrophysics Data System (ADS)

    Lee, Bum-Hoon; Lee, Wonwoo; MacKenzie, Richard; Paranjape, M. B.; Yajnik, U. A.; Yeom, Dong-han

    2013-10-01

    We consider the decay of vortices trapped in the false vacuum of a theory of scalar electrodynamics in 2+1 dimensions. The potential is inspired by models with intermediate symmetry breaking to a metastable vacuum that completely breaks a U(1) symmetry, while in the true vacuum, the symmetry is unbroken. The false vacuum is unstable through the formation of true vacuum bubbles; however, the rate of decay can be extremely long. On the other hand, the false vacuum can contain metastable vortex solutions. These vortices contain the true vacuum inside in addition to a unit of magnetic flux and the appropriate topologically nontrivial false vacuum outside. We numerically establish the existence of vortex solutions which are classically stable; however, they can decay via tunneling. In general terms, they tunnel to a configuration which is a large, thin-walled vortex configuration that is now classically unstable to the expansion of its radius. We compute an estimate for the tunneling amplitude in the semiclassical approximation. We believe our analysis would be relevant to superconducting thin films or superfluids.

  6. Diagnosis of Carpal Tunnel Syndrome

    PubMed Central

    Keith, Michael Warren; Masear, Victoria; Chung, Kevin; Maupin, Kent; Andary, Michael; Amadio, Peter C.; Barth, Richard W.; Watters, William C.; Goldberg, Michael J.; Haralson, Robert H.; Turkelson, Charles M.; Wies, Janet L.

    2016-01-01

    This clinical practice guideline was created to improve patient care by outlining the appropriate information-gathering and decision-making processes involved in managing the diagnosis of carpal tunnel syndrome. The methods used to develop this clinical practice guideline were designed to combat bias, enhance transparency, and promote reproducibility. The guideline’s recommendations are as follows: The physician should obtain an accurate patient history. The physician should perform a physical examination of the patient that may include personal characteristics as well as performing a sensory examination, manual muscle testing of the upper extremity, and provocative and/or discriminatory tests for alternative diagnoses. The physician may obtain electrodiagnostic tests to differentiate among diagnoses. This may be done in the presence of thenar atrophy and/or persistent numbness. The physician should obtain electrodiagnostic tests when clinical and/or provocative tests are positive and surgical management is being considered. If the physician orders electrodiagnostic tests, the testing protocol should follow the American Academy of Neurology/American Association of Neuromuscular and Electrodiagnostic Medicine/American Academy of Physical Medicine and Rehabilitation guidelines for diagnosis of carpal tunnel syndrome. In addition, the physician should not routinely evaluate patients suspected of having carpal tunnel syndrome with new technology, such as magnetic resonance imaging, computed tomography, and pressure-specified sensorimotor devices in the wrist and hand. This decision was based on an additional nonsystematic literature review following the face-to-face meeting of the work group. PMID:19474448

  7. Quiet Supersonic Wind Tunnel Development

    NASA Technical Reports Server (NTRS)

    King, Lyndell S.; Kutler, Paul (Technical Monitor)

    1994-01-01

    The ability to control the extent of laminar flow on swept wings at supersonic speeds may be a critical element in developing the enabling technology for a High Speed Civil Transport (HSCT). Laminar boundary layers are less resistive to forward flight than their turbulent counterparts, thus the farther downstream that transition from laminar to turbulent flow in the wing boundary layer is extended can be of significant economic impact. Due to the complex processes involved experimental studies of boundary layer stability and transition are needed, and these are performed in "quiet" wind tunnels capable of simulating the low-disturbance environment of free flight. At Ames, a wind tunnel has been built to operate at flow conditions which match those of the HSCT laminar flow flight demonstration 'aircraft, the F-16XL, i.e. at a Mach number of 1.6 and a Reynolds number range of 1 to 3 million per foot. This will allow detailed studies of the attachment line and crossflow on the leading edge area of the highly swept wing. Also, use of suction as a means of control of transition due to crossflow and attachment line instabilities can be studied. Topics covered include: test operating conditions required; design requirements to efficiently make use of the existing infrastructure; development of an injector drive system using a small pilot facility; plenum chamber design; use of computational tools for tunnel and model design; and early operational results.

  8. Autonomous Robotic Inspection in Tunnels

    NASA Astrophysics Data System (ADS)

    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.

  9. Models for cryogenic wind tunnels

    NASA Technical Reports Server (NTRS)

    Lawing, Pierce L.

    1989-01-01

    Model requirements, types of model construction methods, and research in new ways to build models are discussed. The 0.3-m Transonic Cryogenic Tunnel was in operation for 16 years and many 2-D airfoil pressure models were tested. In addition there were airfoil models dedicated to transition detection techniques and other specialized research. There were also a number of small 3-D models tested. A chronological development in model building technique is described which led to the construction of many successful models. The difficulties of construction are illustrated by discussing several unsuccessful model fabrication attempts. The National Transonic Facility, a newer and much larger tunnel, was used to test a variety of models including a submarine, transport and fighter configurations, and the Shuttle Orbiter. A new method of building pressure models was developed and is described. The method is centered on the concept of bonding together plates with pressure channels etched into the bond planes, which provides high density pressure instrumentation with minimum demand on parent model material. With care in the choice of materials and technique, vacuum brazing can be used to produce strong bonds without blocking pressure channels and with no bonding voids between channels. Using multiple plates, a 5 percent wing with 96 orifices was constructed and tested in a transonic cryogenic wind tunnel. Samples of test data are presented and future applications of the technology are suggested.

  10. Quantum Tunneling Affects Engine Performance.

    PubMed

    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.

  11. The optimum hypersonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Trimmer, L. L.; Cary, A., Jr.; Voisinet, R. L. P.

    1986-01-01

    The capabilities of existing hypersonic wind tunnels in the U.S. are assessed to form a basis for recommendations for a new, costly facility which would provide data for modeling the hypervelocity aerodynamics envisioned for the new generation of aerospace vehicles now undergoing early studies. Attention is given to the regimes, both entry and aerodynamic, which the new vehicles will encounter, and the shortcomings of data generated for the Orbiter before flight are discussed. The features of foreign-gas, impulse, aeroballistic range, arc-heated and combustion-heated facilities are examined, noting that in any hypersonic wind tunnel the flow must be preheated to prevent liquefaction upon expansion in the test channel. The limitations of the existing facilities and the identification of the regimes which must be studied lead to a description of the characteristics of an optimum hypersonic wind tunnel, including the operations and productivity, the instrumentation, the nozzle design and the flow quality. Three different design approaches are described, each costing at least $100 million to achieve workability.

  12. Water

    MedlinePlus

    ... 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. ...

  13. Wind Tunnel Modeling Of Wind Flow Over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Banks, D.; Cochran, B.

    2010-12-01

    This presentation will describe the finding of an atmospheric boundary layer (ABL) wind tunnel study conducted as part of the Bolund Experiment. This experiment was sponsored by Risø DTU (National Laboratory for Sustainable Energy, Technical University of Denmark) during the fall of 2009 to enable a blind comparison of various air flow models in an attempt to validate their performance in predicting airflow over complex terrain. Bohlund hill sits 12 m above the water level at the end of a narrow isthmus. The island features a steep escarpment on one side, over which the airflow can be expected to separate. The island was equipped with several anemometer towers, and the approach flow over the water was well characterized. This study was one of only two only physical model studies included in the blind model comparison, the other being a water plume study. The remainder were computational fluid dynamics (CFD) simulations, including both RANS and LES. Physical modeling of air flow over topographical features has been used since the middle of the 20th century, and the methods required are well understood and well documented. Several books have been written describing how to properly perform ABL wind tunnel studies, including ASCE manual of engineering practice 67. Boundary layer wind tunnel tests are the only modelling method deemed acceptable in ASCE 7-10, the most recent edition of the American Society of Civil Engineers standard that provides wind loads for buildings and other structures for buildings codes across the US. Since the 1970’s, most tall structures undergo testing in a boundary layer wind tunnel to accurately determine the wind induced loading. When compared to CFD, the US EPA considers a properly executed wind tunnel study to be equivalent to a CFD model with infinitesimal grid resolution and near infinite memory. One key reason for this widespread acceptance is that properly executed ABL wind tunnel studies will accurately simulate flow separation

  14. 1. West portal of Tunnel 26, contextual view to northeast ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. West portal of Tunnel 26, contextual view to northeast from atop Tunnel 25 (HAER CA-201), with Tunnel 27 (HAER CA-203) visible in distance, 210mm lens. View is along new line, with original Central Pacific Transcontinental line crossing over the top above Tunnel 26. - Central Pacific Transcontinental Railroad, Tunnel No. 26, Milepost 133.29, Applegate, Placer County, CA

  15. Micromachined Tunneling Displacement Transducers for Physical Sensors

    NASA Technical Reports Server (NTRS)

    Kenny, T. W.; Kaiser, W. J.; Podosek, J. A.; Rockstad, H. K.; Reynolds, J. K.; Vote, E. C.

    1993-01-01

    We have designed and constructed a series of tunneling sensors which take advantage of the extreme position sensitivity of electron tunneling. In these sensors, a tunneling displacement transducer, based on scanning tunneling microscopy principles, is used to detect the signal-induced motion of a sensor element. Through the use of high-resonant frequency mechanical elements for the transducer, sensors may be constructed which offer wide bandwidth, and are robust and easily operated. Silicon micromachining may be used to fabricate the transducer elements, allowing integration of sensor and control electronics. Examples of tunneling accelerometers and infrared detectors will be discussed. In each case, the use of the tunneling transducer allows miniaturization of the sensor as well as enhancement of the sensor performance.

  16. Endoscopic Resection of the Tarsal Tunnel Ganglion.

    PubMed

    Lui, Tun Hing

    2016-10-01

    The tarsal tunnel ganglion is a cause of posterior tarsal tunnel syndrome. Open resection of the ganglion calls for release of the flexor retinaculum and dissection around the tibial neurovascular bundle. This can induce fibrosis around the tibial nerve. We report the technique of endoscopic resection of the tarsal tunnel ganglion. It is indicated for tarsal tunnel ganglia arising from the adjacent joints or tendon sheaths and compressing the tibial nerve from its deep side. It is contraindicated if there is other pathology of the tarsal tunnel that demands open surgery; if the ganglion compresses the tibial nerve from its superficial side, which calls for a different endoscopic approach using the ganglion portal; or if an intraneural ganglion of the tibial nerve is present. The purpose of this technical note is to describe a minimally invasive approach for endoscopic resection of the tarsal tunnel ganglion.

  17. Fractional tunnelling resonance in plasmonic media

    PubMed Central

    Kang, Ji-Hun; -Han Park, Q.

    2013-01-01

    Metals can transmit light by tunnelling when they possess skin-depth thickness. Tunnelling can be resonantly enhanced if resonators are added to each side of a metal film, such as additional dielectric layers or periodic structures on a metal surface. Here we show that, even with no additional resonators, tunnelling resonance can arise if the metal film is confined and fractionally thin. In a slit waveguide filled with a negative permittivity metallic slab of thickness L, resonance is shown to arise at fractional thicknesses (L = Const./m; m = 1,2,3,…) by the excitation of ‘vortex plasmons'. We experimentally demonstrate fractional tunnelling resonance and vortex plasmons using microwave and negative permittivity metamaterials. The measured spectral peaks of the fractional tunnelling resonance and modes of the vortex plasmons agree with theoretical predictions. Fractional tunnelling resonance and vortex plasmons open new perspectives in resonance physics and promise potential applications in nanotechnology. PMID:23939460

  18. Chaos regularization of quantum tunneling rates.

    PubMed

    Pecora, Louis M; Lee, Hoshik; Wu, Dong-Ho; Antonsen, Thomas; Lee, Ming-Jer; Ott, Edward

    2011-06-01

    Quantum tunneling rates through a barrier separating two-dimensional, symmetric, double-well potentials are shown to depend on the classical dynamics of the billiard trajectories in each well and, hence, on the shape of the wells. For shapes that lead to regular (integrable) classical dynamics the tunneling rates fluctuate greatly with eigenenergies of the states sometimes by over two orders of magnitude. Contrarily, shapes that lead to completely chaotic trajectories lead to tunneling rates whose fluctuations are greatly reduced, a phenomenon we call regularization of tunneling rates. We show that a random-plane-wave theory of tunneling accounts for the mean tunneling rates and the small fluctuation variances for the chaotic systems.

  19. RITD – Wind tunnel testing

    NASA Astrophysics Data System (ADS)

    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

  20. Wind-Tunnel Testing In The 12-Foot Low - Speed Tunnel

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Low-speed wind tunnel test were conducted in the 12 - foot Tunnel at NASA Langley Research center to investigate application of various wing devices on the effect of stall departure resistance at high angles of attack.

  1. Dynamic 3d Modeling of a Canal-Tunnel Using Photogrammetric and Bathymetric Data

    NASA Astrophysics Data System (ADS)

    Moisan, E.; Heinkele, C.; Charbonnier, P.; Foucher, P.; Grussenmeyer, P.; Guillemin, S.; Koehl, M.

    2017-02-01

    This contribution introduces an original method for dynamically surveying the vault and underwater parts of a canal-tunnel for 3D modeling. The recording system, embedded on a barge, is composed of cameras that provide images of the above-water part of the tunnel, and a sonar that acquires underwater 3D profiles. In this contribution we propose to fully exploit the capacities of photogrammetry to deal with the issue of geo-referencing data in the absence of global positioning system (GPS) data. More specifically, we use it both for reconstructing the vault and side walls of the tunnel in 3D and for estimating the trajectory of the boat, which is necessary to rearrange sonar profiles to form the 3D model of the canal. We report on a first experimentation carried out inside a canal-tunnel and show promising preliminary results that illustrate the potentialities of the proposed approach.

  2. Troll Phase I pipelines: Tie-ins to the subsea tunnel

    SciTech Connect

    Hove, F.; Kuhlmann, H.

    1995-12-31

    Subsea approaches to the Norwegian coast are characterized by very rugged topography. Landfall of offshore pipelines therefore often require dedicated subsea tunnel and pipeline tie in concepts. To land the 36 inch and 40 inch offshore pipelines associated with the Troll Phase 1 development, a 4 km long landfall tunnel was constructed terminating at a water depth of 165 m with vertical shaft connections to the seabed. This paper describes the design of the Troll Phase 1 tie-ins of offshore to tunnel pipeline sections. These comprise two main elements, i.e. 180 Te tie-in spools -- which are installed between the offshore pipelines and the piercing shafts -- and prefabricated 450 Te riser bundles -- which are installed into the vertical tunnel piercing shafts.

  3. Resonant TMR inversion in LiF/EuS based spin-filter tunnel junctions

    NASA Astrophysics Data System (ADS)

    Liu, Fen; Yang, Yihang; Xue, Qian; Gao, Zhiwei; Chen, Aixi; Miao, Guo-Xing

    2016-08-01

    Resonant tunneling can lead to inverse tunnel magnetoresistance when impurity levels rather than direct tunneling dominate the transport process. We fabricated hybrid magnetic tunnel junctions of CoFe/LiF/EuS/Ti, with an epitaxial LiF energy barrier joined with a polycrystalline EuS spin-filter barrier. Due to the water solubility of LiF, the devices were fully packaged in situ. The devices showed sizeable positive TMR up to 16% at low bias voltages but clearly inverted TMR at higher bias voltages. The TMR inversion depends sensitively on the thickness of LiF, and the tendency of inversion disappears when LiF gets thick enough and recovers its intrinsic properties.

  4. Wind-Tunnel/Flight Correlation, 1981

    NASA Technical Reports Server (NTRS)

    Mckinney, L. W. (Editor); Baals, D. D. (Editor)

    1982-01-01

    Wind-tunnel/flight correlation activities are reviewed to assure maximum effectiveness of the early experimental programs of the National Transonic Facility (NTF). Topics included a status report of the NTF, the role of tunnel-to-tunnel correlation, a review of past flight correlation research and the resulting data base, the correlation potential of future flight vehicles, and an assessment of the role of computational fluid dynamics.

  5. Aeronautical Wind Tunnels, Europe and Asia

    DTIC Science & Technology

    2006-02-01

    AERONAUTICAL WIND TUNNELS EUROPE AND ASIA Researchers: Katarina David Jenele Gorham Sarah Kim Patrick Miller... Wind Tunnels Europe and Asia 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f...18 Library of Congress – Federal Research Division Aeronautical Wind Tunnels Europe and Asia PREFACE 1 This catalog is a compilation of data on

  6. Effect of Chaos on Relativistic Quantum Tunneling

    DTIC Science & Technology

    2012-06-01

    Effect of chaos on relativistic quantum tunneling This article has been downloaded from IOPscience. Please scroll down to see the full text article...of chaos on relativistic quantum tunneling 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...tunneling dynamics even in the relativistic quantum regime. Similar phenomena have been observed in graphene. A physical theory is developed to

  7. Deep Tunnel's twists and turns -- CSO control in metro Chicago

    SciTech Connect

    Farnan, J.C.; Lue-Hing, C.; O'Connor, T.K.; Rakoczy, J.R.

    1998-07-01

    Metro-Chicago began its search for a comprehensive solution to its severe and then-worsening combined sewer overflow (CSO) pollution and flooding problems even before enactment of the 1972 Federal Clean Water Act. Many studies and extensive interagency cooperation singled out the Tunnel and Reservoir Plan (TARP) as the best means of cost-effectively achieving three anti-pollution and anti-flooding objectives: protect Chicagoland's main drinking water supply--Lake Michigan--from raw sewage backflows; clean up polluted streams; and alleviated basement sewage backups. Owing to TARP's uniqueness, initially there was little or no design, construction or operations experience to draw upon to help implement the project. But since TARP's four systems operate independently, and new tunnel segments are placed into operation as soon as completed, the District has been able to continuously monitor performance and obtain operations feedback. This has enabled ongoing refinement of design, construction, and operational strategy on successive TARP tunnel contracts. Herein is a brief discussion of TARP's development--an evolutionary process with many twists and turns--and of problems and opportunities encountered which resulted in design or operations changes.

  8. Tunneling induced absorption with competing Nonlinearities

    PubMed Central

    Peng, Yandong; Yang, Aihong; Xu, Yan; Wang, Peng; Yu, Yang; Guo, Hongju; Ren, Tingqi

    2016-01-01

    We investigate tunneling induced nonlinear absorption phenomena in a coupled quantum-dot system. Resonant tunneling causes constructive interference in the nonlinear absorption that leads to an increase of more than an order of magnitude over the maximum absorption in a coupled quantum dot system without tunneling. Resonant tunneling also leads to a narrowing of the linewidth of the absorption peak to a sublinewidth level. Analytical expressions show that the enhanced nonlinear absorption is largely due to the fifth-order nonlinear term. Competition between third- and fifth-order nonlinearities leads to an anomalous dispersion of the total susceptibility. PMID:27958303

  9. Observation of density-induced tunneling.

    PubMed

    Jürgensen, Ole; Meinert, Florian; Mark, Manfred J; Nägerl, Hanns-Christoph; Lühmann, Dirk-Sören

    2014-11-07

    We study the dynamics of bosonic atoms in a tilted one-dimensional optical lattice and report on the first direct observation of density-induced tunneling. We show that the interaction affects the time evolution of the doublon oscillation via density-induced tunneling and pinpoint its density and interaction dependence. The experimental data for different lattice depths are in good agreement with our theoretical model. Furthermore, resonances caused by second-order tunneling processes are studied, where the density-induced tunneling breaks the symmetric behavior for attractive and repulsive interactions predicted by the Hubbard model.

  10. Italian and French Experiments on Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Knight, WM

    1920-01-01

    Given here are the results of experiments conducted by Colonel Costanzi of the Italian Army to determine the influence of the surrounding building in which a wind tunnel was installed on the efficiency of the installation, and how the efficiency of the installation was affected by the design of the tunnel. Also given are the results of a series of experiments by Eiffel on 34 models of tunnels of different dimensions. This series of experiments was started in order to find out if, by changing the shape of the nozzle or of the diffuser of the large tunnel at Auteuil, the efficiency of the installation could be improved.

  11. Scanning Tunneling Microscopy Studies of Quasicrystals

    NASA Astrophysics Data System (ADS)

    Becker, Russell S.; Kortan, A. Refik

    The following sections are included: * INTRODUCTION * EXPERIMENTAL * X-RAY DIFFRACTION * SCANNING TUNNELING MICROSCOPY * STRUCTURE MODELLING BASED ON STM * COMPARISON WITH MODELS BASED ON BULK STUDIES * CONCLUSION * REFERENCES

  12. Predictive modelling of ferroelectric tunnel junctions

    NASA Astrophysics Data System (ADS)

    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.

  13. Is carpal tunnel decompression warranted for HNPP?

    PubMed

    Earle, Nicholas; Zochodne, Douglas W

    2013-12-01

    The role of carpal tunnel decompression surgery for patients that have hereditary neuropathy with liability to pressure palsy (HNPP) is currently unknown. Since recovery from carpal tunnel compression is often associated with remyelination or nodal reconstruction rather than axonal regeneration, it is uncertain whether the PMP22 deletion associated with HNPP interrupts myelin or nodal reconstitution. We describe two patients with genetically confirmed HNPP and symptomatic carpal tunnel syndrome that had clinical and electrophysiological improvement after surgical decompression. The findings indicate a capacity for conduction repair in HNPP. They also suggest a need for further investigation and discussion around whether to offer carpal tunnel decompression to symptomatic HNPP patients.

  14. Assessment of Scaled Rotors for Wind Tunnel Experiments.

    SciTech Connect

    Maniaci, David Charles; Kelley, Christopher Lee; Chiu, Phillip

    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.

  15. Low-Speed Wind Tunnel Flow Quality Determination

    DTIC Science & Technology

    2011-09-01

    39 a. Pressure Rake installation ......................................................39 b. Instrument Setup and Tunnel Warmup ...43 b. Instrument Setup and Tunnel Warmup .................................44 2. Conduct of Testing...55 b. Instrument Setup and Tunnel Warmup .................................57 3. CTA Calibration Coefficient Determination

  16. 1. GENERAL VIEW OF ENTRANCE TO BLUE RIDGE TUNNEL (LEFT) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. GENERAL VIEW OF ENTRANCE TO BLUE RIDGE TUNNEL (LEFT) FROM SOUTHEAST. ORIGINAL BLUE RIDGE R.R. (CROZET) TUNNEL IS VISIBLE AT RIGHT. - Chesapeake & Ohio Railroad, Blue Ridge Tunnel, Highway 250 at Rockfish Gap, Afton, Nelson County, VA

  17. NORTHERN END OF VIADUCT WHERE IT ENTERS BATTERY STREET TUNNEL. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    NORTHERN END OF VIADUCT WHERE IT ENTERS BATTERY STREET TUNNEL. LAKE UNION VISIBLE IN BACKGROUND. TUNNEL PROCEEDS IN CUT AND COVER FASHION DIRECTLY BENEATH BATTERY STREET. - Alaskan Way Viaduct and Battery Street Tunnel, Seattle, King County, WA

  18. View of Flume Tunnel #3 through Purple Mountain, showing flume ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of Flume Tunnel #3 through Purple Mountain, showing flume entering into the tunnel. Looking south - Childs-Irving Hydroelectric Project, Childs System, Flume Tunnel No. 3, Forest Service Road 708/502, Camp Verde, Yavapai County, AZ

  19. 4. East portal of Tunnel 25, view to southwest from ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. East portal of Tunnel 25, view to southwest from west end of Tunnel 26 (HAER CA-202), 135mm lens. - Central Pacific Transcontinental Railroad, Tunnel No. 25, Milepost 133.09, Applegate, Placer County, CA

  20. Help Students Tunnel Their Way to Math and Writing Skills.

    ERIC Educational Resources Information Center

    MacMath, Russ

    1987-01-01

    A teacher describes how a cardboard box tunnel was used to capitalize on children's fascination with boxes. The finished tunnel offers opportunities for honing math and writing skills. Layouts for tunnels and related activities are suggested. (MT)

  1. 1. West portal of Tunnel 25, contextual view to northeast ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. West portal of Tunnel 25, contextual view to northeast from Tunnel 24 (HAER CA-200), 135mm lens. - Central Pacific Transcontinental Railroad, Tunnel No. 25, Milepost 133.09, Applegate, Placer County, CA

  2. View of Irving Flume Tunnel #1 showing the steel flume ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of Irving Flume Tunnel #1 showing the steel flume with trestles leading into concrete tunnel. Looking south - Childs-Irving Hydroelectric Project, Irving System, Flume Tunnel No. 1, Forest Service Road 708/502, Camp Verde, Yavapai County, AZ

  3. 4. VIEW FROM MIDDLE ADIT OF WAWONA TUNNEL AT HWY. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW FROM MIDDLE ADIT OF WAWONA TUNNEL AT HWY. 120. TUNNEL #1 IS IN LOWER CENTER OF IMAGE. - Big Oak Flat Road Tunnel No. 1, Through mountain spur on New Big Oak Flat Road, Yosemite Village, Mariposa County, CA

  4. 1. West portal of Tunnel 17, contextual view to northeast, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. West portal of Tunnel 17, contextual view to northeast, 135mm lens. The tunnel penetrates the toe of Dorris Hill, which rises to the left. - Southern Pacific Railroad Natron Cutoff, Tunnel No. 17, Milepost 408, Dorris, Siskiyou County, CA

  5. 340. Caltrans, Photographer October 14, 1935 "TUNNEL WEST PORTAL"; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    340. Caltrans, Photographer October 14, 1935 "TUNNEL - WEST PORTAL"; VIEW OF TUNNEL - WEST PORTAL' UNDER CONSTRUCTION SHOWING EXCAVATION OF TUNNEL AFTER POUR. 5-1669 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

  6. 1. West portal of Tunnel 22, contextual view to the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. West portal of Tunnel 22, contextual view to the northwest, 135mm lens. Tunnel 22 pierces a ridge separating Oakridge from Westfir. - Southern Pacific Railroad Natron Cutoff, Tunnel 22, Milepost 581.85, Oakridge, Lane County, OR

  7. Mars Surface Tunnel Element Concept

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle A.

    2016-01-01

    How crews get into or out of their ascent vehicle has profound implications for Mars surface architecture. Extravehicular Activity (EVA) hatches and Airlocks have the benefit of relatively low mass and high Technology Readiness Level (TRL), but waste consumables with a volume depressurization for every ingress/egress. Perhaps the biggest drawback to EVA hatches or Airlocks is that they make it difficult to keep Martian dust from being tracked back into the ascent vehicle, in violation of planetary protection protocols. Suit ports offer the promise of dust mitigation by keeping dusty suits outside the cabin, but require significant cabin real estate, are relatively high mass, and current operational concepts still require an EVA hatch to get the suits outside for the first EVA, and back inside after the final EVA. This is primarily because current designs don't provide enough structural support to protect the suits from ascent/descent loads or potential thruster plume impingement. For architectures involving more than one surface element-such as an ascent vehicle and a rover or surface habitat-a retractable tunnel is an attractive option. By pushing spacesuit don/doff and EVA operations to an element that remains on the surface, ascended vehicle mass and dust can be minimized. What's more, retractable tunnels provide operational flexibility by allowing surface assets to be re-configured or built up over time. Retractable tunnel functional requirements and design concepts being developed as part of the National Aeronautics and Space Administration's (NASA) Evolvable Mars Campaign (EMC) work will add a new ingress/egress option to the surface architecture trade space.

  8. Full-Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction of Full-Scale Tunnel (FST): 120-Foot Truss hoisting, one and two point suspension. In November 1929, Smith DeFrance submitted his recommendations for the general design of the Full Scale Wind Tunnel. The last on his list concerned the division of labor required to build this unusual facility. He believed the job had five parts and described them as follows: 'It is proposed that invitations be sent out for bids on five groups of items. The first would be for one contract on the complete structure; second the same as first, including the erection of the cones but not the fabrication, since this would be more of a shipyard job; third would cover structural steel, cover, sash and doors, but not cones or foundation; fourth, foundations; and fifth, fabrication of cones.' DeFrance's memorandum prompted the NACA to solicit estimates from a large number of companies. Preliminary designs and estimates were prepared and submitted to the Bureau of the Budget and Congress appropriated funds on February 20, 1929. The main construction contract with the J.A. Jones Company of Charlotte, North Carolina was signed one year later on February 12, 1930. It was a peculiar structure as the building's steel framework is visible on the outside of the building. DeFrance described this in NACA TR No. 459: 'The entire equipment is housed in a structure, the outside walls of which serve as the outer walls of the return passages. The over-all length of the tunnel is 434 feet 6 inches, the width 222 feet, and the maximum height 97 feet. The framework is of structural steel....' (pp. 292-293)

  9. Full-Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction of Full-Scale Tunnel (FST). In November 1929, Smith DeFrance submitted his recommendations for the general design of the Full Scale Wind Tunnel. The last on his list concerned the division of labor required to build this unusual facility. He believed the job had five parts and described them as follows: 'It is proposed that invitations be sent out for bids on five groups of items. The first would be for one contract on the complete structure; second the same as first, including the erection of the cones but not the fabrication, since this would be more of a shipyard job; third would cover structural steel, cover, sash and doors, but not cones or foundation; fourth, foundations; an fifth, fabrication of cones.' DeFrance's memorandum prompted the NACA to solicit estimates from a large number of companies. Preliminary designs and estimates were prepared and submitted to the Bureau of the Budget and Congress appropriated funds on February 20, 1929. The main construction contract with the J.A. Jones Company of Charlotte, North Carolina was signed one year later on February 12, 1930. It was a peculiar structure as the building's steel framework is visible on the outside of the building. DeFrance described this in NACA TR No. 459: 'The entire equipment is housed in a structure, the outside walls of which serve as the outer walls of the return passages. The over-all length of the tunnel is 434 feet 6 inches, the width 222 feet, and the maximum height 97 feet. The framework is of structural steel....' (pp. 292-293).

  10. Oxidation of tunnel barrier metals in magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Yang, J. Joshua; Ladwig, Peter F.; Yang, Ying; Ji, Chengxiang; Chang, Y. Austin; Liu, Feng X.; Pant, Bharat B.; Schultz, Allan E.

    2005-05-01

    The oxidation of an ultrathin metal layer (<1nm) to form an oxide tunnel barrier is of critical importance for the fabrication of magnetic tunnel junctions (MTJs) with low product of resistance and area (R×A). Nonuniform and excessive or insufficient oxidation will occur by using conventional plasma, air, or O2 and noble gas mixtures as oxidation methods. An oxidation method was investigated to oxidize only an ultrathin layer of metal (such as Y) without oxidizing adjacent ferromagnetic thin film layers. We have now demonstrated that a gas mixture of H2O/H2 with a fixed chemical potential of oxygen determined by the relative amounts of the two gases can oxidize Y and Ta thin layers while simultaneously keeping a Co ferromagnetic layer completely unoxidized. This universal method can be used to preferentially oxidize a host of other metals with high tendency to form oxides, such as Zr, Hf, Nb, rare earth metals, etc. and may allow us to access the feasible lower limit of barrier thickness in MTJs.

  11. Fermion tunneling beyond semiclassical approximation

    SciTech Connect

    Majhi, Bibhas Ranjan

    2009-02-15

    Applying the Hamilton-Jacobi method beyond the semiclassical approximation prescribed in R. Banerjee and B. R. Majhi, J. High Energy Phys. 06 (2008) 095 for the scalar particle, Hawking radiation as tunneling of the Dirac particle through an event horizon is analyzed. We show that, as before, all quantum corrections in the single particle action are proportional to the usual semiclassical contribution. We also compute the modifications to the Hawking temperature and Bekenstein-Hawking entropy for the Schwarzschild black hole. Finally, the coefficient of the logarithmic correction to entropy is shown to be related with the trace anomaly.

  12. Metal-Vacuum-Metal Tunneling

    DTIC Science & Technology

    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

  13. Full-Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    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

  14. Davies Critical Point and Tunneling

    NASA Astrophysics Data System (ADS)

    La, Hoseong

    2012-04-01

    From the point of view of tunneling, the physical meaning of the Davies critical point of a second-order phase transition in the black hole thermodynamics is clarified. At the critical point, the nonthermal contribution vanishes so that the black hole radiation is entirely thermal. It separates two phases: one with radiation enhanced by the nonthermal contribution, the other suppressed by the nonthermal contribution. We show this in both charged and rotating black holes. The phase transition is also analyzed in the cases in which emissions of charges and angular momenta are incorporated.

  15. Wall Interference in Wind Tunnels

    DTIC Science & Technology

    1982-09-01

    d’un d £ faut d’ßtendue des signatures. Sp^cialeinent dans le cas de la correction d’incidence, la pondäration des ecarts de Kp entre les deux parois, de...für Stromungsmechanik der Tech. Univers. Bienroder Weg 3 D -3300 Braunschweig — Germany MrL.H.Ohman Head, High Speed Aerodynamics Lab. National...CORRECTIONS IM ’. • SOLID-WALL TUNNELS FROM MEASUREMENTS OF STATIC PRESSURE AT THE WALLS j t by t P. R. Ashill and D . J. Weeks Aerodynamics

  16. Quantum Tunneling Time: Relativistic Extensions

    NASA Astrophysics Data System (ADS)

    Xu, Dai-Yu; Wang, Towe; Xue, Xun

    2013-11-01

    Several years ago, in quantum mechanics, Davies proposed a method to calculate particle's traveling time with the phase difference of wave function. The method is convenient for calculating the sojourn time inside a potential step and the tunneling time through a potential hill. We extend Davies' non-relativistic calculation to relativistic quantum mechanics, with and without particle-antiparticle creation, using Klein-Gordon equation and Dirac Equation, for different forms of energy-momentum relation. The extension is successful only when the particle and antiparticle creation/annihilation effect is negligible.

  17. Full-Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Modification of entrance cone Full-Scale Tunnel (FST). Smith DeFrance describes the entrance cone in NACA TR 459 as follows: 'The entrance cone is 75 feet in length and in this distance the cross section changes from a rectangle 72 by 110 feet to a 30 by 60 foot elliptic section. The area reduction in the entrance cone is slightly less than 5:1. The shape of the entrance cone was chosen to give as fas as possible a constant acceleration to the air stream and to retain a 9-foot length of nozzle for directing the flow.' (p. 293)

  18. Stress changes ahead of an advancing tunnel

    USGS Publications Warehouse

    Abel, J.F.; Lee, F.T.

    1973-01-01

    Instrumentation placed ahead of three model tunnels in the laboratory and ahead of a crosscut driven in a metamorphic rock mass detected stress changes several tunnel diameters ahead of the tunnel face. Stress changes were detected 4 diameters ahead of a model tunnel drilled into nearly elastic acrylic, 2??50 diameters ahead of a model tunnel drilled into concrete, and 2 diameters ahead of a model tunnel drilled into Silver Plume Granite. Stress changes were detected 7??50 diameters ahead of a crosscut driven in jointed, closely foliated gneisses and gneissic granites in an experimental mine at Idaho Springs, Colorado. These results contrast markedly with a theoretical elastic estimate of the onset of detectable stress changes at 1 tunnel diameter ahead of the tunnel face. A small compressive stress concentration was detected 2 diameters ahead of the model tunnel in acrylic, 1.25 diameters ahead of the model tunnel in concrete, and 1 diameter ahead of the model tunnel in granite. A similar stress peak was detected about 6 diameters ahead of the crosscut. No such stress peak is predicted from elastic theory. The 3-dimensional in situ stress determined in the field demonstrate that geologic structure controls stress orientations in the metamorphic rock mass. Two of the computed principal stresses are parallel to the foliation and the other principal stress is normal to it. The principal stress orientations vary approximately as the foliation attitude varies. The average horizontal stress components and the average vertical stress component are three times and twice as large, respectively, as those predicted from the overburden load. An understanding of the measured stress field appears to require the application of either tectonic or residual stress components, or both. Laboratory studies indicate the presence of proportionately large residual stresses. Mining may have triggered the release of strain energy, which is controlled by geologic structure. ?? 1973.

  19. Spin-polarized Inelastic Electron Tunneling Spectroscopy of Molecular Magnetic Tunnel Junctions

    SciTech Connect

    Wang Wenyong; Richter, Curt A.

    2007-09-26

    In this study, we fabricate molecular magnetic tunnel junctions and demonstrate that inelastic electron tunneling spectroscopy technique can be utilized to inspect such junctions to investigate the existence of desired molecular species in the device area. Tunneling magnetoresistance measurements have been carried out and spin-dependent tunneling transport has been observed. Bias-dependence of the tunneling resistance has also been detected. IETS measurements at different magnetic field suggested that the TMR bias-dependence was likely caused by the inelastic scattering due to the molecular vibrations.

  20. Scheme for accelerating quantum tunneling dynamics

    NASA Astrophysics Data System (ADS)

    Khujakulov, Anvar; Nakamura, Katsuhiro

    2016-02-01

    We propose a scheme of the exact fast forwarding of standard quantum dynamics for a charged particle. The present idea allows the acceleration of both the amplitude and the phase of the wave function throughout the fast-forward time range and is distinct from that of Masuda and Nakamura [Proc. R. Soc. A 466, 1135 (2010), 10.1098/rspa.2009.0446], which enabled acceleration of only the amplitude of the wave function on the way. We apply the proposed method to the quantum tunneling phenomena and obtain the electromagnetic field to ensure the rapid penetration of wave functions through a tunneling barrier. Typical examples described here are (1) an exponential wave packet passing through the δ -function barrier and (2) the opened Moshinsky shutter with a δ -function barrier just behind the shutter. We elucidate the tunneling current in the vicinity of the barrier and find a remarkable enhancement of the tunneling rate (tunneling power) due to the fast forwarding. In the case of a very high barrier, in particular, we present the asymptotic analysis and exhibit a suitable driving force to recover a recognizable tunneling current. The analysis is also carried out on the exact acceleration of macroscopic quantum tunneling with use of the nonlinear Schrödinger equation, which accommodates a tunneling barrier.

  1. Virtual Processes and Quantum Tunnelling as Fictions

    ERIC Educational Resources Information Center

    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…

  2. Tunnelling from non-localised initial states

    NASA Technical Reports Server (NTRS)

    Bowcock, Peter; Gregory, Ruth

    1991-01-01

    An approach for calculating tunneling amplitudes from a nonlocalized initial state is presented. Generalizing the matching conditions and equations of motion to allow for complex momentum permits a description of tunneling in the presence of so-called classical motion. Possible applications of the method are presented.

  3. F-16XL Wind Tunnel Models

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a multiple exposure image of the F-16XL Supersonic Laminar Flow Control (SLFC) model in the Unitary Plan Wind Tunnel. This wind tunnel test was conducted to verify design pressure distributions for the SLFC flight experiment (see modified port wing) and to obtain simulator coefficients for stability and control investigations.

  4. Prediction of swelling rocks strain in tunneling

    NASA Astrophysics Data System (ADS)

    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.

  5. Graphene tunnel junctions with aluminum oxide barrier

    NASA Astrophysics Data System (ADS)

    Feng, Ying; Trainer, Daniel J.; Chen, Ke

    2016-10-01

    We report a development of graphene tunnel junctions made by chemical vapor deposition grown graphene and sputtered aluminum insulating by an in-situ grown aluminum oxide. The thin oxide layer formed in between the metal layer and the two-dimensional material is a crucial part of a tunnel junction. We characterized surface morphology of oxide layers and studied tunneling spectra of lead and silver tunnel junctions to estimate the quality of the aluminum oxide. The Brinkman-Rowell-Dynes model was applied to fit the conductance-voltage plots to calculate the thickness of oxide layers. Junctions with graphene both on bottom and on top were fabricated and their tunneling properties were characterized after exposure to air for weeks to test time stability. Furthermore, the resistances of graphene tunnel junctions with aluminum oxide formed naturally and in an oxygen atmosphere were studied. Our results demonstrate that in-situ aluminum oxide is an effective barrier for graphene tunnel junctions. The methods of barrier formation enable the realization of more tunnel devices and circuits based on graphene.

  6. PRESSURE DEPENDENCE OF PHONON ASSISTED INTERBAND TUNNELING,

    DTIC Science & Technology

    Since very much is known about the band structure of germanium and of its dependence on stress, one can expect to obtain detailed information about... dependence of the relative change of tunneling current with hydrostatic pressure, in Sb-doped germanium tunnel junctions at 4.2 K. This effect is re

  7. Scanning scene tunnel for city traversing.

    PubMed

    Zheng, Jiang Yu; Zhou, Yu; Milli, Panayiotis

    2006-01-01

    This paper proposes a visual representation named scene tunnel for capturing urban scenes along routes and visualizing them on the Internet. We scan scenes with multiple cameras or a fish-eye camera on a moving vehicle, which generates a real scene archive along streets that is more complete than previously proposed route panoramas. Using a translating spherical eye, properly set planes of scanning, and unique parallel-central projection, we explore the image acquisition of the scene tunnel from camera selection and alignment, slit calculation, scene scanning, to image integration. The scene tunnels cover high buildings, ground, and various viewing directions and have uniformed resolutions along the street. The sequentially organized scene tunnel benefits texture mapping onto the urban models. We analyze the shape characteristics in the scene tunnels for designing visualization algorithms. After combining this with a global panorama and forward image caps, the capped scene tunnels can provide continuous views directly for virtual or real navigation in a city. We render scene tunnel dynamically by view warping, fast transmission, and flexible interaction. The compact and continuous scene tunnel facilitates model construction, data streaming, and seamless route traversing on the Internet and mobile devices.

  8. Object-Based Attention and Cognitive Tunneling

    ERIC Educational Resources Information Center

    Jarmasz, Jerzy; Herdman, Chris M.; Johannsdottir, Kamilla Run

    2005-01-01

    Simulator-based research has shown that pilots cognitively tunnel their attention on head-up displays (HUDs). Cognitive tunneling has been linked to object-based visual attention on the assumption that HUD symbology is perceptually grouped into an object that is perceived and attended separately from the external scene. The present research…

  9. 49 CFR 177.810 - Vehicular tunnels.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Vehicular tunnels. 177.810 Section 177.810 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS CARRIAGE BY PUBLIC HIGHWAY § 177.810 Vehicular tunnels. Except as regards...

  10. Enhancing metal-insulator-insulator-metal tunnel diodes via defect enhanced direct tunneling

    SciTech Connect

    Alimardani, Nasir; Conley, John F.

    2014-08-25

    Metal-insulator-insulator-metal tunnel diodes with dissimilar work function electrodes and nanolaminate Al{sub 2}O{sub 3}-Ta{sub 2}O{sub 5} bilayer tunnel barriers deposited by atomic layer deposition are investigated. This combination of high and low electron affinity insulators, each with different dominant conduction mechanisms (tunneling and Frenkel-Poole emission), results in improved low voltage asymmetry and non-linearity of current versus voltage behavior. These improvements are due to defect enhanced direct tunneling in which electrons transport across the Ta{sub 2}O{sub 5} via defect based conduction before tunneling directly through the Al{sub 2}O{sub 3}, effectively narrowing the tunnel barrier. Conduction through the device is dominated by tunneling, and operation is relatively insensitive to temperature.

  11. Full-Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Wing and nacelle set-up in Full-Scale Tunnel (FST). The NACA conducted drag tests in 1931 on a P3M-1 nacelle which were presented in a special report to the Navy. Smith DeFrance described this work in the report's introduction: 'Tests were conducted in the full-scale wind tunnel on a five to four geared Pratt and Whitney Wasp engine mounted in a P3M-1 nacelle. In order to simulate the flight conditions the nacelle was assembled on a 15-foot span of wing from the same airplane. The purpose of the tests was to improve the cooling of the engine and to reduce the drag of the nacelle combination. Thermocouples were installed at various points on the cylinders and temperature readings were obtained from these by the power plants division. These results will be reported in a memorandum by that division. The drag results, which are covered by this memorandum, were obtained with the original nacelle condition as received from the Navy with the tail of the nacelle modified, with the nose section of the nacelle modified, with a Curtiss anti-drag ring attached to the engine, with a Type G ring developed by the N.A.C.A., and with a Type D cowling which was also developed by the N.A.C.A.' (p. 1)

  12. Full-Scale Tunnel (FST)

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Modification of entrance cone of the Full-Scale Tunnel (FST). To the left are the FST guide vanes which Smith DeFrance described in NACA TR No. 459: 'The air is turned at the four corners of each return passage by guide vanes. The vanes are of the curved-airfoil type formed by two intersecting arcs with a rounded nose. The arcs were so chosen as to give a practically constant area through the vanes.' (p. 295) These vanes 'have chords of 3 feet 6 inches and are spaced at 0.41 of a chord length. By a proper adjustment of the angular setting of the vanes, a satisfactory velocity distribution has been obtained and no honeycomb has been found necessary.' (p. 295). Close inspection of the photograph will reveal a number of workers on the scaffolding. The heights were great and the work was quite dangerous. In October 1930, one construction worker working on the roof of the tunnel would die when he stepped off the planking to fetch a tool and fell through an unsupported piece of Careystone to the floor some 70 feet below.

  13. CARPAL TUNNEL SYNDROME IN CYCLISTS

    PubMed Central

    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.

  14. STM tunneling spectroscopy on high Tc superconductors

    SciTech Connect

    Hasegawa, T.; Nantoh, M.; Ogino, M.

    1995-08-01

    STM tunneling spectroscopy has been performed on the bulk single crystals of BiSrCaCuO (BSCCO) and the epitaxial thin films of YBaCuO (YBCO) at cryogenic temperatures. The STM images and tunneling spectra observed on the (001) surfaces can be classified into three cases; (1) Atomic image is visible. However, the tunneling spectrum shows semiconducting or smeared superconducting gap structures, depending on the tip-sample distance. (2) Clear atomic image can be obtained. But, the tunneling spectrum shows flat bottom region with quite low zero bias conductance. (3) Tunneling spectra demonstrate gapless behavior, independent of the tip-sample separation. These observations support the quasi-2D electronic picture in which s-wave like 2D superconducting layers are coupled with each other through the Josephson effect.

  15. Nonlinear femtosecond laser induced scanning tunneling microscopy.

    PubMed

    Dey, Shirshendu; Mirell, Daniel; Perez, Alejandro Rodriguez; Lee, Joonhee; Apkarian, V Ara

    2013-04-21

    We demonstrate ultrafast laser driven nonlinear scanning tunneling microscopy (STM), under ambient conditions. The design is an adaptation of the recently introduced cross-polarized double beat method, whereby z-polarized phase modulated fields are tightly focused at a tunneling junction consisting of a sharp tungsten tip and an optically transparent gold film as substrate. We demonstrate the prerequisites for ultrafast time-resolved STM through an operative mechanism of nonlinear laser field-driven tunneling. The spatial resolution of the nonlinear laser driven STM is determined by the local field intensity. Resolution of 0.3 nm-10 nm is demonstrated for the intensity dependent, exponential tunneling range. The demonstration is carried out on a junction consisting of tungsten tip and gold substrate. Nano-structured gold is used for imaging purposes, to highlight junction plasmon controlled tunneling in the conductivity limit.

  16. PUREX Storage Tunnels dangerous waste permit application

    SciTech Connect

    Not Available

    1990-09-01

    The Hanford Site is operated by the US Department of Energy-Richland Operations Office. The PUREX Storage Tunnels are a storage unit located on the Hanford Site. The unit consists of two earth-covered railroad tunnels that are used for storage of process equipment (some containing dangerous waste) removed from the PUREX Plant. Radioactively contaminated equipment is loaded on railroad cars and remotely transferred into the tunnels for long-term storage. Westinghouse Hanford Company is a major contractor to the US Department of Energy-Richland Operations Office and serves as a co-operator of the PUREX Storage Tunnels, the waste management unit addressed by this permit application. This appendix contains Tunnel 1 Construction Specifications, HWS-5638, consisting of 49 pages.

  17. Air quality inside a tunnel tube and in the vicinity of the tunnel portals

    SciTech Connect

    Pucher, K.; Zwiener, K.

    1997-12-31

    Due to the continually growing number of motor vehicles more and more roads are reaching the limits of their capability. This has led to slowly moving traffic and longer persisting traffic blockages. In cities and conurbation centers especially this leads to complete traffic chaos. The pollutant emissions of vehicles that only move very little mostly lead to high pollutant burdens also and in some circumstances to poor air quality. Therefore in more and more cities one is attempting to get traffic moving again through efficient road tunnels and underground lines and thereby also reduce the pollutant emission. Typical examples of such developments are the Central Artery Tunnel Project in Boston, the planned Ringroad tunnel in Stockholm and the Ringtunnel projects in Paris. Tunnel constructions and underground lines in densely built-up areas are also planned in many small cities. For all these tunnel projects the following points concerning the air quality are to be observed. On the one hand, a tunnel construction can accommodate traffic and thereby reduce the traffic blockages in the vicinity of the tunnel, so long as no additional traffic is attracted. This would therefore lead to a reduction of the pollutant burden and also to an improvement in the air quality in large areas of further surroundings of the tunnel construction. On the other hand, at the portals of the tunnel, alongside mobile pollutant sources from vehicles travelling on the already existing road, a stationary pollutant source of the tunnel ventilation flowing out from the tunnel portal also results. It is then to be investigated how high the emerging pollutant concentrations will be at the portal of the planned tunnel and how these pollutants will disseminate. In this report therefore, the air quality in the tunnel as well as in the vicinity of the tunnel portals will be more closely dealt with.

  18. The role of sediment supply in esker formation and ice tunnel evolution

    NASA Astrophysics Data System (ADS)

    Burke, Matthew J.; Brennand, Tracy A.; Sjogren, Darren B.

    2015-05-01

    Meltwater is an important part of the glacier system as it can directly influence ice sheet dynamics. Although it is important that ice sheet models incorporate accurate information about subglacial meltwater processes, the relative inaccessibility of contemporary ice sheet beds makes direct investigation challenging. Former ice sheet beds contain a wealth of meltwater landforms such as eskers that, if accurately interpreted, can provide detailed insight into the hydrology of former ice sheets. Eskers are the casts of ice-walled channels and are a common landform within the footprint of the last Laurentide and Cordilleran Ice Sheets. In south-western Alberta, esker distribution suggests that both water and sediment supply may have been important controls; the longest esker ridge segments are located within meltwater valleys partially filled by glaciofluvial sediments, whereas the shortest esker ridge segments are located in areas dominated by clast-poor till. Through detailed esker ridge planform and crest-type mapping, and near surface geophysics we reveal morpho-sedimentary relationships that suggest esker sedimentation was dynamic, but that esker distribution and architecture were primarily governed by sediment supply. Through comparison of these data with data from eskers elsewhere, we suggest three formative scenarios: 1) where sediment supply and flow powers were high, coarse sediment loads result in rapid deposition, and rates of thermo-mechanical ice tunnel growth is exceeded by the rate of ice tunnel closure due to sediment infilling. High sedimentation rates reduce ice tunnel cross-sectional area, cause an increase in meltwater flow velocity and force ice tunnel growth. Thus, ice tunnel growth is fastest where sedimentation rate is highest; this positive feedback results in a non-uniform ice tunnel geometry, and favours macroform development and non-uniform ridge geometry. 2) Where sediment supply is limited, but flow power high, the rate of sedimentation

  19. Resonant tunneling dynamics and the related tunneling time

    NASA Astrophysics Data System (ADS)

    Xiao, Zhi; Huang, Hai; Lu, Xiang-Xiang

    2015-01-01

    In close analogy with optical Fabry-Pérot (FP) interferometer, we rederive the transmission and reflection coefficients of tunneling through a rectangular double barrier (RDB). Based on the same analogy, we also get an analytic finesse formula for its filtering capability of matter waves, and with this formula, we reproduce the RDB transmission rate in exactly the same form as that of FP interferometer. Compared with the numerical results obtained from the original finesse definition, we find the formula works well. Next, we turn to the elusive time issue in tunneling, and show that the "generalized Hartman effect" can be regarded as an artifact of the opaque limit βl → ∞. In the thin barrier approximation, phase (or dwell) time does depend on the free inter-barrier distance d asymptotically. Further, the analysis of transmission rate in the neighborhood of resonance shows that, phase (or dwell) time could be a good estimate of the resonance lifetime. The numerical results from the uncertainty principle support this statement. This fact can be viewed as a support to the idea that, phase (or dwell) time is a measure of lifetime of energy stored beneath the barrier. To confirm this result, we shrink RDB to a double Dirac δ-barrier. The landscape of the phase (or dwell) time in k and d axes fits excellently well with the lifetime estimates near the resonance. As a supplementary check, we also apply phase (or dwell) time formula to the rectangular well, where no obstacle exists to the propagation of particle. However, due to the self-interference induced by the common cavity-like structure, phase (or dwell) time calculation leads to a counterintuitive "slowing down" effect, which can be explained appropriately by the lifetime assumptions.

  20. CH2M Hill cleared in tunnel explosion case

    SciTech Connect

    Krizan, W.G.; Bradford, H.; Schriener, J.

    1993-09-06

    One of the most critical issues in industry is whether architects and engineers should be held responsible for construction safety on jobsites. The Occupational Safety and Health Administration says yes under certain conditions. But the Occupational Safety and Health Review Commission has overturned one application of that view on appeal in a controversial case. It involves a unit of Denver-based CH2M Hill Cos.'s role as program manager for the Milwaukee Metropolitan Sewerage District (MMSD) on its $2.2-billion water pollution abatement program. On May 5, 1989, OSHA cited CH2M Hill Central Inc. for 46 willful safety violations in connection with a 1988 methane tunnel explosion that killed three supervisors of contractor S.A. Healy Co., Chicago, Healy was charged with 68 violations. Healy encountered methane while boring CT-7, a two-mile crosstown tunnel. It evacuated the site, but didn't follow the evacuation plan. It failed to shut down all nonessential equipment and the supervisors returned after waiting only 17 minutes instead of the one hour minimum. CH2M Hill's citations and proposed $460,000 fine for violating OSHA's construction standards were for having 45 pieces of unapproved electrical equipment in the tunnel and improper ventilation equipment. CH2M Hill claimed the standards did not apply to it because the firm did not engage in construction work, exercise substantial supervision over the construction work performed by the contractor or create or control the hazardous condition.

  1. [From 1878 to 2006 - working in hyperbaric conditions during tunnelling].

    PubMed

    Le Péchon, Jean-Claude

    2006-01-01

    To review the impact of Paul Bert's researches on hyperbaric work in tunnelling, the status of the industry in 1878 is described. Mostly based on the application of Triger's machine it was used to mine coal below the water table or to dig foundations for bridges in rivers or close to rivers. The results and conclusions obtained by Paul Bert which are applicable in that particular field are listed. The major steps of research or remarkable achievements in construction between 1878 and 2006 are presented as well as the evolution of decompression tables. Improvement in safety and conditions of caisson workers has been continuous until the technical revolution resulting from the introduction and the development of tunnelling boring machines (TBM) in the late 80's. TBM technology has resulted in major changes in tunnel construction. Hyperbaric interventions have also changed completely since human operators no longer work in pressurized conditions. Only occasional inspections and repairs are carried out under pressure. Present performance in hyperbaric conditions are reported, and high pressures reached in the 2000's using saturation technology are described. The future of hyperbaric works is also discussed whether for very high pressure, or complete replacement of caisson workers in TBMs. These descriptions show that Paul Bert provides us with very clear directions to improve safety in hyperbaric conditions and that none of his recommendations were mistaken, most being still relevant.

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

    NASA Astrophysics Data System (ADS)

    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

  3. Air Pollution in Road Tunnels

    PubMed Central

    Waller, R. E.; Commins, B. T.; Lawther, P. J.

    1961-01-01

    As a part of a study of pollution of the air by motor vehicles, measurements have been made in two London road tunnels during periods of high traffic density. The concentrations of smoke and polycyclic hydrocarbons found there are much higher than the average values in Central London, but they are of the same order of magnitude as those occurring during temperature inversions on winter evenings when smoke from coal fires accumulates at a low level. An attempt has been made to relate the concentration of each pollutant to the type and amount of traffic. Both diesel and petrol vehicles make some contribution to the amounts of smoke and polycyclic hydrocarbons found in the tunnels, but in the case of smoke, fluoranthene, 1: 2-benzpyrene, pyrene, and 3: 4-benzpyrene, the concentrations appear to be more closely related to the density of diesel traffic than to that of petrol traffic. The concentrations of lead and carbon monoxide have also been determined, and these are very closely related to the density of petrol traffic. During the morning and evening rush hours the mean concentration of carbon monoxide was just over 100 p.p.m. and peak values up to 500 p.p.m. were recorded at times. Oxides of nitrogen were determined in some of the experiments and there was always much more nitric oxide than nitrogen dioxide. Eye irritation was experienced but its cause was not investigated. The concentration of pollution in the tunnels does not appear to be high enough to create any special hazards for short-term exposures. The amosphere at peak periods may become very dirty and unpleasant and the concentration of carbon monoxide would be sufficient to produce some effect over a period of several hours' continuous exposure. The total emission of pollution from road vehicles must still be small in comparison with that from coal fires, but the effect of traffic on the concentration of smoke, polycyclic hydrocarbons, carbon monoxide, and lead in the air of city streets deserves

  4. Medial Patellofemoral Ligament Reconstruction Femoral Tunnel Accuracy

    PubMed Central

    Hiemstra, Laurie A.; Kerslake, Sarah; Lafave, Mark

    2017-01-01

    Background: Medial patellofemoral ligament (MPFL) reconstruction is a procedure aimed to reestablish the checkrein to lateral patellar translation in patients with symptomatic patellofemoral instability. Correct femoral tunnel position is thought to be crucial to successful MPFL reconstruction, but the accuracy of this statement in terms of patient outcomes has not been tested. Purpose: To assess the accuracy of femoral tunnel placement in an MPFL reconstruction cohort and to determine the correlation between tunnel accuracy and a validated disease-specific, patient-reported quality-of-life outcome measure. Study Design: Case series; Level of evidence, 4. Methods: Between June 2008 and February 2014, a total of 206 subjects underwent an MPFL reconstruction. Lateral radiographs were measured to determine the accuracy of the femoral tunnel by measuring the distance from the center of the femoral tunnel to the Schöttle point. Banff Patella Instability Instrument (BPII) scores were collected a mean 24 months postoperatively. Results: A total of 155 (79.5%) subjects had adequate postoperative lateral radiographs and complete BPII scores. The mean duration of follow-up (±SD) was 24.4 ± 8.2 months (range, 12-74 months). Measurement from the center of the femoral tunnel to the Schöttle point resulted in 143 (92.3%) tunnels being categorized as “good” or “ideal.” There were 8 failures in the cohort, none of which occurred in malpositioned tunnels. The mean distance from the center of the MPFL tunnel to the center of the Schöttle point was 5.9 ± 4.2 mm (range, 0.5-25.9 mm). The mean postoperative BPII score was 65.2 ± 22.5 (range, 9.2-100). Pearson r correlation demonstrated no statistically significant relationship between accuracy of femoral tunnel position and BPII score (r = –0.08; 95% CI, –0.24 to 0.08). Conclusion: There was no evidence of a correlation between the accuracy of MPFL reconstruction femoral tunnel in relation to the Schöttle point and

  5. Influence of trap-assisted tunneling on trap-assisted tunneling current in double gate tunnel field-effect transistor

    NASA Astrophysics Data System (ADS)

    Zhi, Jiang; Yi-Qi, Zhuang; Cong, Li; Ping, Wang; Yu-Qi, Liu

    2016-02-01

    Trap-assisted tunneling (TAT) has attracted more and more attention, because it seriously affects the sub-threshold characteristic of tunnel field-effect transistor (TFET). In this paper, we assess subthreshold performance of double gate TFET (DG-TFET) through a band-to-band tunneling (BTBT) model, including phonon-assisted scattering and acoustic surface phonons scattering. Interface state density profile (Dit) and the trap level are included in the simulation to analyze their effects on TAT current and the mechanism of gate leakage current. Project supported by the National Natural Science Foundation of China (Grant Nos. 61574109 and 61204092).

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  8. Evaluation of the Sony GDM-FW900 16:10 Aspect Ratio, 24-Inch Diagonal Flat Face CRT Color Monitor

    DTIC Science & Technology

    2007-11-02

    Color Gamut ....................................................................................... 46 II. 23 Color Tracking...daylight color imagery. Other color features include: variable RGB gain/bias, the sRGB color display system. Adjusting the color temperature somewhat...delta u’v’ Pass Color Tracking Not specified Less than 0.013 delta u’v’ between Lmin to Lmax Color Gamut Area Not specified 27% Pixel aspect

  9. Quantitative tunneling spectroscopy of nanocrystals

    SciTech Connect

    First, Phillip N; Whetten, Robert L; Schaaff, T Gregory

    2007-05-25

    The proposed goals of this collaborative work were to systematically characterize the electronic structure and dynamics of 3-dimensional metal and semiconducting nanocrystals using scanning tunneling microscopy/spectroscopy (STM/STS) and ballistic electron emission spectroscopy (BEES). This report describes progress in the spectroscopic work and in the development of methods for creating and characterizing gold nanocrystals. During the grant period, substantial effort also was devoted to the development of epitaxial graphene (EG), a very promising materials system with outstanding potential for nanometer-scale ballistic and coherent devices ("graphene" refers to one atomic layer of graphitic, sp2 -bonded carbon atoms [or more loosely, few layers]). Funding from this DOE grant was critical for the initial development of epitaxial graphene for nanoelectronics

  10. Limited incision carpal tunnel release

    PubMed Central

    Gaba, Sunil; Bhogesha, Sandeep; Singh, Onkar

    2017-01-01

    Background: Carpal tunnel syndrome (CTS) is the most common peripheral entrapment neuropathy. Limited incision techniques for carpal tunnel release are gaining popularity. The main advantages of these techniques are less scar load, less pillar pain, shorter recovery, and return-to-work time. However, the completeness of release, and risk of neurovascular injury are always a concern. We devised a method of limited incision release with two mini-incisions and use of nasal speculum and a probe. We aimed to evaluate the clinical and neurological outcome of this technique. Materials and Methods: Twenty seven cases (9 male and 18 female, age 28–56 years) of isolated CTS cases were enrolled in the study. A total of 33 hands (six bilateral) underwent limited incision carpal tunnel release. In this study, two mini-incisions were used and release was done with the help of nasal speculum. Evaluation preoperatively and in 6 months and at 1-year postoperatively was done, namely, (a) clinical status examination, (b) motor testing using grip and pinch dynamometer, and (c) neurological outcome measure using nerve conduction study. Results: All the patients had good clinical and neurological outcome with no recurrence during followup. The first symptom to get relieved was night pains, with a mean of 4.5 days (range 2–14 days). Compared to pain, improvement of sensory symptoms was delayed; the mean duration was 42.8 days (range 30–90 days). Scar tenderness was present only for a mean duration of 9 days (range 7–21 days). The mean duration for patients to resume their daily activities was12 days (range 7–28 days) and to work was 32 days (range 21–90 days). The hand grip showed mean values of 45.12 ± 16.16 g/mm2 preoperatively, 62.45 ± 18.86 g/mm2 at 6 months postoperatively, and 74.87 ± 20.35 g/mm2 at 1-year postoperatively. The key pinch showed mean values of 11.27 ± 3.51 g/mm2 preoperatively, 20.181 ± 3.94 g/mm2 at 6 months postoperatively, and 27.96 ± 94.42 g/mm2

  11. Direct Approach to Quantum Tunneling

    NASA Astrophysics Data System (ADS)

    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.

  12. Tunnel effect wave energy detection

    NASA Technical Reports Server (NTRS)

    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.

  13. Langley Field wind tunnel apparatus

    NASA Technical Reports Server (NTRS)

    Bacon, D L

    1921-01-01

    The difficulties experienced in properly holding thin tipped or tapered airfoils while testing on an N.P.L. type aerodynamic balance even at low air speeds, and the impossibility of holding even solid metal models at the high speeds attainable at the National Advisory Committee's wind tunnel, necessitated the design of a balance which would hold model airfoils of any thickness and at speeds up to 150 m.p.h. In addition to mechanical strength and rigidity, it was highly desirable that the balance readings should require a minimum amount of correction and mathematical manipulation in order to obtain the lift and drag coefficients and the center of pressure. The balance described herein is similar to one in use at the University of Gottingen, the main difference lying in the addition of a device for reading the center of pressure directly, without the necessity of any correction whatsoever. Details of the design and operation of the device are given.

  14. Giant tunneling magnetoresistance in silicene

    SciTech Connect

    Wang, Yu; Lou, Yiyi

    2013-11-14

    We have theoretically studied ballistic electron transport in silicene under the manipulation of a pair of ferromagnetic gate. Transport properties like transmission and conductance have been calculated by the standard transfer matrix method for parallel and antiparallel magnetization configurations. It is demonstrated here that, due to the stray field-induced wave-vector filtering effect, remarkable difference in configuration-dependent transport gives rise to a giant tunneling magnetoresistance. In combination with the peculiar buckled structure of silicene and its electric tunable energy gap, the receiving magnetoresistance can be efficiently modulated by the externally-tunable stray field, electrostatic potential, and staggered sublattice potential, providing some flexible strategies to construct silicene-based nanoelectronic device.

  15. Rudolf Hermann, wind tunnels and aerodynamics

    NASA Astrophysics Data System (ADS)

    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.

  16. WT - WIND TUNNEL PERFORMANCE ANALYSIS

    NASA Technical Reports Server (NTRS)

    Viterna, L. A.

    1994-01-01

    WT was developed to calculate fan rotor power requirements and output thrust for a closed loop wind tunnel. The program uses blade element theory to calculate aerodynamic forces along the blade using airfoil lift and drag characteristics at an appropriate blade aspect ratio. A tip loss model is also used which reduces the lift coefficient to zero for the outer three percent of the blade radius. The application of momentum theory is not used to determine the axial velocity at the rotor plane. Unlike a propeller, the wind tunnel rotor is prevented from producing an increase in velocity in the slipstream. Instead, velocities at the rotor plane are used as input. Other input for WT includes rotational speed, rotor geometry, and airfoil characteristics. Inputs for rotor blade geometry include blade radius, hub radius, number of blades, and pitch angle. Airfoil aerodynamic inputs include angle at zero lift coefficient, positive stall angle, drag coefficient at zero lift coefficient, and drag coefficient at stall. WT is written in APL2 using IBM's APL2 interpreter for IBM PC series and compatible computers running MS-DOS. WT requires a CGA or better color monitor for display. It also requires 640K of RAM and MS-DOS v3.1 or later for execution. Both an MS-DOS executable and the source code are provided on the distribution medium. The standard distribution medium for WT is a 5.25 inch 360K MS-DOS format diskette in PKZIP format. The utility to unarchive the files, PKUNZIP, is also included. WT was developed in 1991. APL2 and IBM PC are registered trademarks of International Business Machines Corporation. MS-DOS is a registered trademark of Microsoft Corporation. PKUNZIP is a registered trademark of PKWare, Inc.

  17. Rectangular tunnel boring machine and method

    SciTech Connect

    Snyder, L.L.

    1984-12-04

    A machine for boring a tunnel having an end face wall, a roof wall, a bottom wall, and opposite side walls. The machine comprises a rotatable cutting wheel means having an annular peripheral wall supporting a plurality of cutting devices and a generally convex-shaped upper wall supporting a plurality of cutting devices. The cutting wheel means is rotatable about an axis of rotation which is inclined in a forward direction relative to a plane perpendicular to the longitudinal axis of the tunnel for simultaneously cutting the tunnel face along two intersecting surfaces defined by the cutting devices on the annular peripheral wall and the cutting devices on the convex-shape upper wall. Support shoe means are mounted beneath the cutting wheel means for movably supporting the cutting wheel means on the tunnel floor. Drive motor means are mounted on the support shoe means and are operatively associated with the cutting wheel means for causing rotation of the cutting wheel means relative to the tunnel face and the support shoe means. Thrust means are connected to the support shoe means for advancing the cutting wheel means and the support shoe means toward the tunnel face. Gripping means are associated with the thrust means for gripping engagement with the opposite tunnel side walls to prevent axial rearward movement as the cutting wheel means and the support shoe means are advanced toward the tunnel face. Vertical and horizontal steering means for changing the direction of advance of the machine are described. Paddle means and conveyor means for removing rock cuttings from the end face of the tunnel are disclosed. Shield means for shielding workers from dust and debris and for containing the cuttings are also described.

  18. Support of the eight-foot high-temperature tunnel modifications project

    NASA Technical Reports Server (NTRS)

    Hodges, Donald Y.; Shebalin, John V.

    1987-01-01

    An ultrasonic level sensor was developed to measure the liquid level in a storage vessel under high pressures, namely up to 6000 psi. The sensor is described. A prototype sensor was installed in the cooling-water storage vessel of the Eight-Foot High-Temperature Tunnel. Plans are being made to install the readout instrument in the control room, so that tunnel operators can monitor the water level during the course of a tunnel run. It was discovered that the sensor will operate at cryogenic temperatures. Consequently, a sensor will be installed in the modified Eight-Foot High-Temperature Tunnel to measure the sound speed of liquid oxygen (LOX) as it is transferred from a storage vessel to the tunnel combustor at pressure of about 3000 psi. The sound speed is known to be a reliable indicator of contamination of LOX by pressurized gaseous nitrogen, which will be used to effect the transfer. Subjecting the sensor to a temperature cycle from room temperature to liquid nitrogen temperature and back again several times revealed no deterioration in sensor performance. The method using this sensor is superior to the original method, which was to bleed samples of LOX from the storage vessel to an independent chamber for measurement of the sound speed.

  19. Hydrogeological impacts of a railway tunnel in fractured Precambrian gneiss rocks (south-eastern Norway)

    NASA Astrophysics Data System (ADS)

    Kværner, Jens; Snilsberg, Petter

    2013-11-01

    Groundwater monitoring along the Romeriksporten tunnel, south-eastern Norway, provided an opportunity for studying the impacts of tunnelling on groundwater in fractured Precambrian gneiss rocks, and examining relations between bedrock hydrology, tectonic weakness zones and catchments. Tunnel leakage resulted in groundwater drawdown up to 35 m in weakness zones, converted groundwater discharge zones into recharge zones, and affected groundwater chemistry. The magnitude of drawdown and fluctuations in groundwater level differed between weakness zones, and varied with distance from the tunnel route, tunnel leakage, and recharge from catchments. Clear differences in groundwater level and fluctuation patterns indicated restricted groundwater flow between weakness zones. The groundwater drawdowns demonstrated coherent water-bearing networks to 180-m depth in faults and fracture zones. Similar groundwater levels with highly correlated fluctuations demonstrated hydraulic connectivity within fracture zones. Different groundwater drawdown and leakage in weakness zones with different appearance and influence of tectonic events demonstrated the importance of the geological history for bedrock hydrogeology. Water injection into the bedrock counteracted groundwater drawdowns. Even moderate leakage to underground constructions may lead to large groundwater drawdown in areas with small groundwater recharge. Hydrogeological interpretation of tectonic weakness zones should occur in the context of geological history and local catchment hydrology.

  20. Preliminary wind tunnel tests on the pedal wind turbine

    NASA Astrophysics Data System (ADS)

    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.

  1. Dissipation and tunneling in quantum Hall bilayers.

    PubMed

    Jack, Robert L; Lee, Derek K K; Cooper, Nigel R

    2004-09-17

    We discuss the interplay between transport and intrinsic dissipation in quantum Hall bilayers, within the framework of a simple thought experiment. We compute, for the first time, quantum corrections to the semiclassical dynamics of this system. This allows us to reinterpret tunneling measurements on these systems. We find a strong peak in the zero-temperature tunneling current that arises from the decay of Josephson-like oscillations into incoherent charge fluctuations. In the presence of an in-plane field, resonances in the tunneling current develop an asymmetric line shape.

  2. Carpal tunnel syndrome - anatomical and clinical correlations.

    PubMed

    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.

  3. Wind tunnel pressurization and recovery system

    NASA Technical Reports Server (NTRS)

    Pejack, Edwin R.; Meick, Joseph; Ahmad, Adnan; Lateh, Nordin; Sadeq, Omar

    1988-01-01

    The high density, low toxicity characteristics of refrigerant-12 (dichlorofluoromethane) make it an ideal gas for wind tunnel testing. Present limitations on R-12 emissions, set to slow the rate of ozone deterioration, pose a difficult problem in recovery and handling of large quantities of R-12. This preliminary design is a possible solution to the problem of R-12 handling in wind tunnel testing. The design incorporates cold temperature condensation with secondary purification of the R-12/air mixture by adsorption. Also discussed is the use of Freon-22 as a suitable refrigerant for the 12 foot wind tunnel.

  4. Advancing Test Capabilities at NASA Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Bell, James

    2015-01-01

    NASA maintains twelve major wind tunnels at three field centers capable of providing flows at 0.1 M 10 and unit Reynolds numbers up to 45106m. The maintenance and enhancement of these facilities is handled through a unified management structure under NASAs Aeronautics and Evaluation and Test Capability (AETC) project. The AETC facilities are; the 11x11 transonic and 9x7 supersonic wind tunnels at NASA Ames; the 10x10 and 8x6 supersonic wind tunnels, 9x15 low speed tunnel, Icing Research Tunnel, and Propulsion Simulator Laboratory, all at NASA Glenn; and the National Transonic Facility, Transonic Dynamics Tunnel, LAL aerothermodynamics laboratory, 8 High Temperature Tunnel, and 14x22 low speed tunnel, all at NASA Langley. This presentation describes the primary AETC facilities and their current capabilities, as well as improvements which are planned over the next five years. These improvements fall into three categories. The first are operations and maintenance improvements designed to increase the efficiency and reliability of the wind tunnels. These include new (possibly composite) fan blades at several facilities, new temperature control systems, and new and much more capable facility data systems. The second category of improvements are facility capability advancements. These include significant improvements to optical access in wind tunnel test sections at Ames, improvements to test section acoustics at Glenn and Langley, the development of a Supercooled Large Droplet capability for icing research, and the development of an icing capability for large engine testing. The final category of improvements consists of test technology enhancements which provide value across multiple facilities. These include projects to increase balance accuracy, provide NIST-traceable calibration characterization for wind tunnels, and to advance optical instruments for Computational Fluid Dynamics (CFD) validation. Taken as a whole, these individual projects provide significant

  5. Tunnelling time in strong field ionisation

    NASA Astrophysics Data System (ADS)

    Landsman, Alexandra S.; Keller, Ursula

    2014-10-01

    We revisit the common approaches to tunnelling time in the context of attoclock experiments. These experiments measure tunnelling time using close-to-circularly polarised light of the infrared ultrashort laser pulse. We test the sensitivity of the attoclock measurements of tunnelling time to non-adiabatic effects, as described by a well-known theoretical model first developed by Perelomov, Popov, and Terent'ev. We find that in the case of ionisation of helium, both adiabatic and non-adiabatic theories give very similar predictions for ionisations times over a wide intensity range typical of ultrafast experiments.

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

    PubMed

    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 < 0.001), with an increase of >62 mm(2) at 120 mmHg. Carpal arch height, length, and width also significantly changed with carpal tunnel pressure (p < 0.05). As 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.

  7. 1. West portal of Tunnel 23, contextual view to the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. West portal of Tunnel 23, contextual view to the west-northwest, 380mm lens. Tunnel 22 pierces the toe of Lookout Point. Note that the tracks have been realigned toward the Willamette River to bypass Tunnel 23. - Southern Pacific Railroad Natron Cutoff, Tunnel 23, Milepost 584.5, Westfir, Lane County, OR

  8. 43 CFR 3832.41 - What is a tunnel site?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false What is a tunnel site? 3832.41 Section 3832.41 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.41 What is a tunnel site? A tunnel...

  9. 1. West portal of Tunnel 27 in distance, contextual view ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. West portal of Tunnel 27 in distance, contextual view to northeast looking past Tunnel 26 (HAER CA-202) from atop east portal of Tunnel 25 (HAER CA-201), 380mm lens. - Central Pacific Transcontinental Railroad, Tunnel No. 27, Milepost 133.9, Applegate, Placer County, CA

  10. Westfacing portals within Open Cut No. 2 (South Bergen Tunnel ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    West-facing portals within Open Cut No. 2 (South Bergen Tunnel on right, North Bergen Tunnel see HAER No. NJ-136) on left), from within the opposite portal of the South Bergen Tunnel, looking east - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

  11. 43 CFR 3832.41 - What is a tunnel site?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false What is a tunnel site? 3832.41 Section 3832.41 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.41 What is a tunnel site? A tunnel...

  12. 43 CFR 3832.41 - What is a tunnel site?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false What is a tunnel site? 3832.41 Section 3832.41 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.41 What is a tunnel site? A tunnel...

  13. 43 CFR 3832.41 - What is a tunnel site?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false What is a tunnel site? 3832.41 Section 3832.41 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.41 What is a tunnel site? A tunnel...

  14. Eastfacing portals within Open Cut No. 2 (South Bergen Tunnel ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    East-facing portals within Open Cut No. 2 (South Bergen Tunnel on left, North Bergen Tunnel see HAER No. NJ-136 on right), from the South Bergen Tunnel tracks, looking west - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

  15. Westfacing portals within Open Cut No. 1 (South Bergen Tunnel ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    West-facing portals within Open Cut No. 1 (South Bergen Tunnel see HAER No. NJ-137 on left, North Bergen Tunnel on right), from the North Bergen Tunnel tracks, looking west - Delaware, Lackawanna & Western Railroad, North Bergen Tunnel, Through Bergen Hill from Prospect Street at Ogden Avenue to John F. Kennedy Boulevard at Beacon Avenue, Jersey City, Hudson County, NJ

  16. Eastfacing portals within Open Cut No. 1 (South Bergen Tunnel ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    East-facing portals within Open Cut No. 1 (South Bergen Tunnel see HAER No. NJ-137 on left, North Bergen Tunnel on right), from the North Bergen Tunnel tracks, looking east - Delaware, Lackawanna & Western Railroad, North Bergen Tunnel, Through Bergen Hill from Prospect Street at Ogden Avenue to John F. Kennedy Boulevard at Beacon Avenue, Jersey City, Hudson County, NJ

  17. 1. West portal of Tunnel 34, contextual view to northeast ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. West portal of Tunnel 34, contextual view to northeast from inside east end of Tunnel 33 (Cape Horn Tunnel), 135mm lens with electronic flash fill. - Central Pacific Transcontinental Railroad, Tunnel No. 34, Milepost 145.4, Colfax, Placer County, CA

  18. The Interaction Between Shield, Ground and Tunnel Support in TBM Tunnelling Through Squeezing Ground

    NASA Astrophysics Data System (ADS)

    Ramoni, M.; Anagnostou, G.

    2011-01-01

    When planning a TBM drive in squeezing ground, the tunnelling engineer faces a complex problem involving a number of conflicting factors. In this respect, numerical analyses represent a helpful decision aid as they provide a quantitative assessment of the effects of key parameters. The present paper investigates the interaction between the shield, ground and tunnel support by means of computational analysis. Emphasis is placed on the boundary condition, which is applied to model the interface between the ground and the shield or tunnel support. The paper also discusses two cases, which illustrate different methodical approaches applied to the assessment of a TBM drive in squeezing ground. The first case history—the Uluabat Tunnel (Turkey)—mainly involves the investigation of TBM design measures aimed at reducing the risk of shield jamming. The second case history—the Faido Section of the Gotthard Base Tunnel (Switzerland)—deals with different types of tunnel support installed behind a gripper TBM.

  19. Research and test facilities

    NASA Technical Reports Server (NTRS)

    1993-01-01

    A description is given of each of the following Langley research and test facilities: 0.3-Meter Transonic Cryogenic Tunnel, 7-by 10-Foot High Speed Tunnel, 8-Foot Transonic Pressure Tunnel, 13-Inch Magnetic Suspension & Balance System, 14-by 22-Foot Subsonic Tunnel, 16-Foot Transonic Tunnel, 16-by 24-Inch Water Tunnel, 20-Foot Vertical Spin Tunnel, 30-by 60-Foot Wind Tunnel, Advanced Civil Transport Simulator (ACTS), Advanced Technology Research Laboratory, Aerospace Controls Research Laboratory (ACRL), Aerothermal Loads Complex, Aircraft Landing Dynamics Facility (ALDF), Avionics Integration Research Laboratory, Basic Aerodynamics Research Tunnel (BART), Compact Range Test Facility, Differential Maneuvering Simulator (DMS), Enhanced/Synthetic Vision & Spatial Displays Laboratory, Experimental Test Range (ETR) Flight Research Facility, General Aviation Simulator (GAS), High Intensity Radiated Fields Facility, Human Engineering Methods Laboratory, Hypersonic Facilities Complex, Impact Dynamics Research Facility, Jet Noise Laboratory & Anechoic Jet Facility, Light Alloy Laboratory, Low Frequency Antenna Test Facility, Low Turbulence Pressure Tunnel, Mechanics of Metals Laboratory, National Transonic Facility (NTF), NDE Research Laboratory, Polymers & Composites Laboratory, Pyrotechnic Test Facility, Quiet Flow Facility, Robotics Facilities, Scientific Visualization System, Scramjet Test Complex, Space Materials Research Laboratory, Space Simulation & Environmental Test Complex, Structural Dynamics Research Laboratory, Structural Dynamics Test Beds, Structures & Materials Research Laboratory, Supersonic Low Disturbance Pilot Tunnel, Thermal Acoustic Fatigue Apparatus (TAFA), Transonic Dynamics Tunnel (TDT), Transport Systems Research Vehicle, Unitary Plan Wind Tunnel, and the Visual Motion Simulator (VMS).

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation

    NASA Astrophysics Data System (ADS)

    Livingstone, Stephen J.; Clark, Chris D.

    2016-07-01

    Tunnel valleys have been widely reported on the bed of former ice sheets and are considered an important expression of subglacial meltwater drainage. Although known to have been cut by erosive meltwater flow, the water source and development of channels has been widely debated; ranging between outburst flood events through to gradually occurring channel propagation. We have mapped and analysed the spatial pattern and morphometry of tunnel valleys and associated glacial landforms along the southern sector of the former Laurentide Ice Sheet from high-resolution digital elevation models. Around 2000 tunnel valleys have been mapped, revealing an organised pattern of sub-parallel, semi-regularly spaced valleys that form in distinctive clusters. The tunnel valleys are typically < 20 km long, and 0.5-3 km wide, although their width varies considerably down-valley. They preferentially terminate at moraines, which suggests that formation is time dependent; while we also observe some tunnel valleys that have grown headwards out of hill-hole pairs. Analysis of cross-cutting relationships between tunnel valleys, moraines and outwash fans permits reconstruction of channel development in relation to the retreating ice margin. This palaeo-drainage reconstruction demonstrates incremental growth of most valleys, with some used repeatedly or for long periods, during deglaciation, while others were abandoned shortly after their formation. Our data and interpretation support gradual (rather than a single-event) formation of most tunnel valleys with secondary contributions from flood drainage of subglacial and or supraglacially stored water down individual tunnel valleys. The distribution and morphology of tunnel valleys is shown to be sensitive to regional factors such as basal thermal regime, ice and bed topography, timing and climate.

  2. Methods for the fabrication of thermally stable magnetic tunnel junctions

    SciTech Connect

    Chang, Y. Austin; Yang, Jianhua J.; Ladwig, Peter F.

    2009-08-25

    Magnetic tunnel junctions and method for making the magnetic tunnel junctions are provided. The magnetic tunnel junctions are characterized by a tunnel barrier oxide layer sandwiched between two ferromagnetic layers. The methods used to fabricate the magnetic tunnel junctions are capable of completely and selectively oxidizing a tunnel junction precursor material using an oxidizing gas containing a mixture of gases to provide a tunnel junction oxide without oxidizing the adjacent ferromagnetic materials. In some embodiments the gas mixture is a mixture of CO and CO.sub.2 or a mixture of H.sub.2 and H.sub.2O.

  3. Wind tunnel tests of space shuttle solid rocket booster insulation material in the aerothermal tunnel c

    NASA Technical Reports Server (NTRS)

    Hartman, A. S.; Nutt, K. W.

    1982-01-01

    Wind tunnel tests of the space shuttle Solid Rocket Booster Insulation were conducted in the von Karman Gas Dynamics Facility Tunnel C. For these tests, Tunnel C was run at Mach 4 with a total temperature of 1100-1440 and a total pressure of 100 psia. Cold wall heating rates were changed by varying the test article support wedge angle. Selected results are presented to illustrate the test techniques and typical data obtained.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    DTIC Science & Technology

    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

  6. Observation of a vacuum tunnel gap in a transmission electron microscope using a micromechanical tunneling microscope

    NASA Astrophysics Data System (ADS)

    Lutwyche, M. I.; Wada, Y.

    1995-05-01

    This letter reports the observation of the vacuum tunnel gap between two conductors using a high resolution transmission electron microscope. A 2.5 mm square micromachined tunneling microscope chip has been fabricated with a minimum feature size of 0.4 μm. The chip fits into a modified side-entry type transmission electron microscope holder. The tunnel gap is controlled by a purpose-built feedback controller. The micromachines work reliably during observation of the tip apex in a transmission electron microscope, allowing the voltage and current to be changed while the tunnel gap is observed.

  7. Long-tunneled versus short-tunneled external ventricular drainage: Prospective experience from a developing country

    PubMed Central

    Tahir, Muhammad Zubair; Sobani, Zain A.; Murtaza, Muhammed; Enam, Syed Ather

    2016-01-01

    Background: External ventricular drains (EVD) are commonly utilized for temporary diversion of cerebrospinal fluid (CSF). Many neurosurgeons prefer long-tunneled EVDs in their routine practice. However, it is still unclear whether this extended tunneling helps in reducing CSF infection. Keeping this in mind, we decided to compare infection rates in long-tunneled versus short-tunneled EVDs in the setting of a developing country. Materials and Methods: A prospective study of 60 patients was conducted. Consenting patients who underwent short-tunneled (Group A) or long-tunneled (Group B) EVDs between January 2008 and June 2009 were followed during the course of their inpatient care. All operational protocol was standardized during the trial. Serial samples of CSF were analyzed to detect infection. Results: Mean age of patients was 33.6 years with 32 males (53.3%). Mean duration of long-tunneled EVD was 13.4 ± 7.2 days, whereas that of short-tunneled EVD was 5.3 ± 2.7 days (P < 0.001). Three patients with long-tunneled EVD (10.0%), whereas one patient with short-tunneled EVD (3.3%) developed drain-related infections; however, this was non-significant (P = 0.301). However, patients with short-tunneled EVD got infected earlier on day 3when compared with the long-tunneled EVDs, which got infected after a mean duration of 7.3 days. The overall risk of infection for long-tunneled EVDs was 7.46 per 1,000 ventricular drainage days which was comparable to the risk of 6.33 per 1,000 ventricular drainage days seen for short-tunneled EVDs. Conclusion: Long-tunneled EVDs appear to only delay potential infections without having any effect on the actual risk of infection. Long-tunneled EVD in a resource-limited setting is technically challenging and may not yield additional benefits to the patient. However, larger and prospective studies are needed to establish the rate of infections and other complications. PMID:27057216

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

    NASA Astrophysics Data System (ADS)

    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.

  9. 1. East portal of Tunnel 4, view to west with ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. East portal of Tunnel 4, view to west with east portal of Tunnel 38 (HAER CA-211) visible in distance, 135mm lens with electronic flash fill. This tunnel was photographed to provide context, because even though somewhat enlarged, it illustrates the nature of the unlined hard rock tunnels typical of the original Central Pacific construction in 1868. - Central Pacific Transcontinental Railroad, Tunnel No. 4, Milepost 180.95, Cisco, Placer County, CA

  10. Construction of Foundation for 15-Foot Spin Tunnel

    NASA Technical Reports Server (NTRS)

    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.

  11. Review of Aeronautical Wind Tunnel Facilities

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The nation's aeronautical wind tunnel facilities constitute a valuable technological resource and make a significant contribution to the global supremacy of U.S. aircraft, both civil and military. At the request of NASA, the National Research Council's Aeronautics and Space Engineering Board organized a commitee to review the state of repair, adequacy, and future needs of major aeronautical wind tunnel facilities in meeting national goals. The comittee identified three main areas where actions are needed to sustain the capability of NASA's aeronautical wind tunnel facilities to support the national aeronautical research and development activities: tunnel maintenance and upgrading, productivity enhancement, and accommodation of new requirements (particularly in hypersonics). Each of these areas are addressed and the committee recommendations for appropriate actions presented.

  12. Dielectric Sensors Based on Electromagnetic Energy Tunneling

    PubMed Central

    Siddiqui, Omar; Kashanianfard, Mani; Ramahi, Omar

    2015-01-01

    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. PMID:25835188

  13. V/STOL wind-tunnel testing

    NASA Technical Reports Server (NTRS)

    Koenig, D. G.

    1984-01-01

    Factors influencing effective program planning for V/STOL wind-tunnel testing are discussed. The planning sequence itself, which includes a short checklist of considerations that could enhance the value of the tests, is also described. Each of the considerations, choice of wind tunnel, type of model installation, model development and test operations, is discussed, and examples of appropriate past and current V/STOL test programs are provided. A short survey of the moderate to large subsonic wind tunnels is followed by a review of several model installations, from two-dimensional to large-scale models of complete aircraft configurations. Model sizing, power simulation, and planning are treated, including three areas is test operations: data-acquisition systems, acoustic measurements in wind tunnels, and flow surveying.

  14. Influence of classical resonances on chaotic tunneling

    SciTech Connect

    Mouchet, Amaury; Eltschka, Christopher; Schlagheck, Peter

    2006-08-15

    Dynamical tunneling between symmetry-related stable modes is studied in the periodically driven pendulum. We present strong evidence that the tunneling process is governed by nonlinear resonances that manifest within the regular phase-space islands on which the stable modes are localized. By means of a quantitative numerical study of the corresponding Floquet problem, we identify the trace of such resonances not only in the level splittings between near-degenerate quantum states, where they lead to prominent plateau structures, but also in overlap matrix elements of the Floquet eigenstates, which reveal characteristic sequences of avoided crossings in the Floquet spectrum. The semiclassical theory of resonance-assisted tunneling yields good overall agreement with the quantum-tunneling rates, and indicates that partial barriers within the chaos might play a prominent role.

  15. 49 CFR 177.810 - Vehicular tunnels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... kind, character, or quantity of any hazardous material permitted by such regulations to be transported through any urban vehicular tunnel used for mass transportation. [Amdt. 177-52, 46 FR 5316, Jan. 19,...

  16. AMELIA Tests in NASA Wind Tunnel

    NASA Video Gallery

    This report from "This Week @ NASA" describes recent aerodynamic tests of a subscale model of the Advanced Model for Extreme Lift and Improved Aeroacoustics, or "AMELIA," in a NASA wind tunnel. The...

  17. NASA Now: Engineering Design: Wind Tunnel Testing

    NASA Video Gallery

    Dr. Norman W. Schaeffler, a NASA aerospace research engineer, describes how wind tunnels work and how aircraft designers use them to understand aerodynamic forces at low speeds. Learn the advantage...

  18. Tertiary interactions within the ribosomal exit tunnel.

    PubMed

    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.

  19. Carpal Tunnel Syndrome: Physical Therapy or Surgery?

    PubMed

    2017-03-01

    Carpal tunnel syndrome causes pain, numbness, and weakness in the wrist and hand. Nearly 50% of all work-related injuries are linked to carpal tunnel syndrome, and people with this injury are more likely to miss work because of it. Patients with carpal tunnel syndrome can be treated with physical therapy or surgery. Although surgery may be considered when the symptoms are severe, more than a third of patients do not return to work within 8 weeks after an operation. Based on the potential side effects and risks of surgery, patients often ask if they might try physical therapy first. An article in the March 2017 issue of JOSPT assesses the effectiveness of therapy and surgery to treat carpal tunnel syndrome. J Orthop Sports Phys Ther 2017;47(3):162. doi:10.2519/jospt.2017.0503.

  20. Tunnels Used in Community School Plan

    ERIC Educational Resources Information Center

    School Management, 1972

    1972-01-01

    In a Springfield, Massachusetts, school design, tunnels housing community facilities will make it possible to utilize otherwise unusable land and will create neighborhood ties in an area undergoing urban renewal. (Author)

  1. Tunneling magnetoresistive heads for magnetic data storage.

    PubMed

    Mao, Sining

    2007-01-01

    Spintronics is emerging to be a new form of nanotechnologies, which utilizes not only the charge but also spin degree of freedom of electrons. Spin-dependent tunneling transport is one of the many kinds of physical phenomena involving spintronics, which has already found industrial applications. In this paper, we first provide a brief review on the basic physics and materials for magnetic tunnel junctions, followed more importantly by a detailed coverage on the application of magnetic tunneling devices in magnetic data storage. The use of tunneling magnetoresistive reading heads has helped to maintain a fast growth of areal density, which is one of the key advantages of hard disk drives as compared to solid-state memories. This review is focused on the first commercial tunneling magnetoresistive heads in the industry at an areal density of 80 approximately 100 Gbit/in2 for both laptop and desktop Seagate hard disk drive products using longitudinal media. The first generation tunneling magnetoresistive products utilized a bottom stack of tunnel junctions and an abutted hard bias design. The output signal amplitude of these heads was 3 times larger than that of comparable giant magnetoresistive devices, resulting in a 0.6 decade bit error rate gain over the latter. This has enabled high component and drive yields. Due to the improved thermal dissipation of vertical geometry, the tunneling magnetoresistive head runs cooler with a better lifetime performance, and has demonstrated similar electrical-static-discharge robustness as the giant magnetoresistive devices. It has also demonstrated equivalent or better process and wafer yields compared to the latter. The tunneling magnetoresistive heads are proven to be a mature and capable reader technology. Using the same head design in conjunction with perpendicular recording media, an areal density of 274 Gbit/in2 has been demonstrated, and advanced tunneling magnetoresistive heads can reach 311 Gbit/in2. Today, the

  2. Wind tunnel simulations of aerolian processes

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1984-01-01

    The characteristics of aerolian (wind) activity as a surface modifying process on Earth, Mars, Venus, and appropriate satellites was determined. A combination of spacecraft data analysis, wind tunnel simulations, and terrestrial field analog studies were used to determine these characteristics. Wind tunnel experiments simulating Venusian surface conditions demonstrate that rolling of particles may be an important mode of transport by winds on Venus and that aerolian processes in the dense atmosphere may share attributes of both aerolian and aqueous environments on Earth.

  3. Low Power Band to Band Tunnel Transistors

    DTIC Science & Technology

    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

  4. Tarsal tunnel syndrome: ultrasonographic and MRI features.

    PubMed

    Machiels, F; Shahabpour, M; De Maeseneer, M; Schmedding, E; Wylock, P; Osteaux, M

    1999-04-01

    Tarsal tunnel syndrome is a well-known but rare entrapment neuropathy involving the posterior tibial nerve in the tarsal tunnel, a fibro-osseous channel extending from the medial aspect of the ankle to the midfoot. Posttraumatic fibrosis, ganglion cyst, tenosynovitis, tumor of the nerves or other structures, dilated or tortuous veins can cause significant nerve compression in this anatomic region. Herein, we present the typical ultrasonographic and magnetic resonance features of this disorder in patient with a ganglion cyst.

  5. Automatic control of cryogenic wind tunnels

    NASA Technical Reports Server (NTRS)

    Balakrishna, S.

    1989-01-01

    Inadequate Reynolds number similarity in testing of scaled models affects the quality of aerodynamic data from wind tunnels. This is due to scale effects of boundary-layer shock wave interaction which is likely to be severe at transonic speeds. The idea of operation of wind tunnels using test gas cooled to cryogenic temperatures has yielded a quantrum jump in the ability to realize full scale Reynolds number flow similarity in small transonic tunnels. In such tunnels, the basic flow control problem consists of obtaining and maintaining the desired test section flow parameters. Mach number, Reynolds number, and dynamic pressure are the three flow parameters that are usually required to be kept constant during the period of model aerodynamic data acquisition. The series of activity involved in modeling, control law development, mechanization of the control laws on a microcomputer, and the performance of a globally stable automatic control system for the 0.3-m Transonic Cryogenic Tunnel (TCT) are discussed. A lumped multi-variable nonlinear dynamic model of the cryogenic tunnel, generation of a set of linear control laws for small perturbation, and nonlinear control strategy for large set point changes including tunnel trajectory control are described. The details of mechanization of the control laws on a 16 bit microcomputer system, the software features, operator interface, the display and safety are discussed. The controller is shown to provide globally stable and reliable temperature control to + or - 0.2 K, pressure to + or - 0.07 psi and Mach number to + or - 0.002 of the set point value. This performance is obtained both during large set point commands as for a tunnel cooldown, and during aerodynamic data acquisition with intrusive activity like geometrical changes in the test section such as angle of attack changes, drag rake movements, wall adaptation and sidewall boundary-layer removal. Feasibility of the use of an automatic Reynolds number control mode with

  6. Detection of underground structures and tunnels

    SciTech Connect

    Mack, J.M.; Moses, R.W.; Kelly, R.E.; Flynn, E.R.; Kraus, R.H.; Cogbill, A.H.; Stolarczyk, L.G.

    1996-09-01

    This is the final report of a one year, Laboratory Directed Research and Development project at Los Alamos National Laboratory. There is a continuing need in the United States defense and drug interdiction for effective over, convert, and standoff means of detecting underground tunnels, structures, and objects. This project sought to begin an assessment of electromagnetic and gravitational gradient detection approaches to the detection of underground structures and tunnels.

  7. Semiconductor tunnel junction with enhancement layer

    DOEpatents

    Klem, John F.; Zolper, John C.

    1997-01-01

    The incorporation of a pseudomorphic GaAsSb layer in a runnel diode structure affords a new degree of freedom in designing runnel junctions for p-n junction device interconnects. Previously only doping levels could be varied to control the tunneling properties. This invention uses the valence band alignment band of the GaAsSb with respect to the surrounding materials to greatly relax the doping requirements for tunneling.

  8. Semiconductor tunnel junction with enhancement layer

    DOEpatents

    Klem, J.F.; Zolper, J.C.

    1997-10-21

    The incorporation of a pseudomorphic GaAsSb layer in a runnel diode structure affords a new degree of freedom in designing runnel junctions for p-n junction device interconnects. Previously only doping levels could be varied to control the tunneling properties. This invention uses the valence band alignment band of the GaAsSb with respect to the surrounding materials to greatly relax the doping requirements for tunneling. 5 figs.

  9. Tunnel junctions, cantilevers, and potentials

    NASA Astrophysics Data System (ADS)

    Tanner, Shawn

    We have developed a process for making sub-micrometer dimensional cantilevers, clamped beams, and more complicate electro-mechanical structures that carry integrated electrical leads. Such objects are perhaps useful as test structures for connecting to and measuring the electrical properties of molecular sized objects, as high frequency electromechanical components for radio and microwave frequency applications, and as sensor components for studying the fluctuation physics of small machines. Our process uses two realigned electron-beam lithography steps, a thin film angled deposition system, and differential removal of sacrificial aluminum layers to produce freely suspended sub-micron electromechanical components. We have produced cantilevers and beams on a variety of substrates (silica, silicon, and poly-imide) and have produced insulating, conductive, and multi-layer mechanical structures. We have measured mechanical resonances in the 10 MHz range by electrostatically actuating the cantilevers while in a magnetic field (3500 gauss) and measuring the voltage that results across the front edge of the cantilever. Two structures are fabricated sharing a common ground so that a balanced detection technique can be used to eliminate background signals. Due to the square dependence of the electrostatic force on the voltage, they can be resonated by a drive voltage of 1/2 the natural frequency or at the natural frequency. Two separate attempts have been made to apply these resonators. First, a process was developed to integrate a tunnel junction with the cantilever. These devices can possibly be used for probing small-scale systems such as molecules. We have verified the exponential variation of the tunneling resistance with both substrate flex and electrostatic gating. Second, a novel gate structure was developed to create a double potential well for resonator motion. This is accomplished by placing a multilayer structure in front of the hairpin cantilever consisting two

  10. Optical fiber Bragg gratings for tunnel surveillance

    NASA Astrophysics Data System (ADS)

    Nellen, Philipp M.; Frank, Andreas; Broennimann, Rolf; Sennhauser, Urs J.

    2000-06-01

    We report on application tests of novel sensor elements for long term surveillance of tunnels. The sensors are made of glass fiber reinforced polymers (GFRP) with embedded optical fiber Bragg gratings. The tests were made in a tunnel near Sargans in Switzerland and we will present strain and temperature data of more than one year of operation of the sensor elements. Two sensor types were tested. First, GFRP rockbolts with a diameter of 22 mm were produced. They have a load-bearing function as anchors for tunnel or mine roofs and in addition measure distributed strain fields and temperature with embedded optical fiber Bragg grating arrays. Rockbolts are key elements during construction and operation of tunnels. Data about strain inside the rockbolts can support decision about precautions to be taken and reveal information about the long term movement of the rock. Second, thin and flexible GFRP wires of 3 mm in diameter were found to be robust and versatile sensors not only for tunnel surveillance but for many civil engineering applications where they can be attached or embedded (e.g., in concrete). The fabrication of both sensor types and solutions for the connection of the embedded fiber sensors to a fiber cable will be presented. Moreover, laboratory and tunnel data of functionality and long term stability tests will be discussed and compared.

  11. Nonlinear tunneling in two-dimensional lattices

    SciTech Connect

    Brazhnyi, V. A.; Konotop, V. V.; Kuzmiak, V.; Shchesnovich, V. S.

    2007-08-15

    We present a thorough analysis of the nonlinear tunneling of Bose-Einstein condensates in static and accelerating two-dimensional lattices within the framework of the mean-field approximation. We deal with nonseparable lattices, considering different initial atomic distributions in highly symmetric states. For an analytical description of the condensate before instabilities develop, we derive several few-mode models, analyzing essentially both nonlinear and quasilinear regimes of tunneling. By direct numerical simulations, we show that two-mode models provide an accurate description of tunneling when either initially two states are populated or tunneling occurs between two stable states. Otherwise, a two-mode model may give only useful qualitative hints for understanding tunneling, but does not reproduce many features of the phenomenon. This reflects the crucial role of instabilities developed due to two-body interactions resulting in a non-negligible population of the higher bands. This effect becomes even more pronounced in the case of accelerating lattices. In the latter case we show that the direction of the acceleration is a relevant physical parameter which affects the tunneling by changing the atomic rates at different symmetric states and by changing the numbers of bands involved in the atomic transfer.

  12. Radio-frequency scanning tunnelling microscopy.

    PubMed

    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.

  13. 8-Foot High Speed Tunnel (HST)

    NASA Technical Reports Server (NTRS)

    1953-01-01

    Semi-automatic readout equipment installed in the 1950s used for data recording and reduction in the 8-Foot High Speed Tunnel (HST). A 1957 NACA report on wind tunnel facilities at Langley included these comments on the data recording and reduction equipment for the 8-foot HST: 'The data recording and reduction equipment used for handling steady force and pressure information at the Langley 8-foot transonic tunnel is similar to that described for the Langley 16-foot transonic tunnel. Very little dynamic data recording equipment, however, is available.' The description of the 16-foot transonic tunnel equipment is as follows: 'A semiautomatic force data readout system provides tabulated raw data and punch card storage of raw data concurrent with the operation of the wind tunnel. Provision is made for 12 automatic channels of strain gage-data output, and eight channels of four-digit manually operated inputs are available for tabulating and punching constants, configuration codes, and other information necessary for data reduction and identification. The data are then processed on electronic computing machines to obtain the desired coefficients. These coefficients and their proper identification are then machine tabulated to provide a printed record of the results. The punched cards may also be fed into an automatic plotting device for the preparation of plots necessary for data analysis.'

  14. Calibration of transonic and supersonic wind tunnels

    NASA Technical Reports Server (NTRS)

    Reed, T. D.; Pope, T. C.; Cooksey, J. M.

    1977-01-01

    State-of-the art instrumentation and procedures for calibrating transonic (0.6 less than M less than 1.4) and supersonic (M less than or equal to 3.5) wind tunnels were reviewed and evaluated. Major emphasis was given to transonic tunnels. Continuous, blowdown and intermittent tunnels were considered. The required measurements of pressure, temperature, flow angularity, noise and humidity were discussed, and the effects of measurement uncertainties were summarized. A comprehensive review of instrumentation currently used to calibrate empty tunnel flow conditions was included. The recent results of relevant research are noted and recommendations for achieving improved data accuracy are made where appropriate. It is concluded, for general testing purposes, that satisfactory calibration measurements can be achieved in both transonic and supersonic tunnels. The goal of calibrating transonic tunnels to within 0.001 in centerline Mach number appears to be feasible with existing instrumentation, provided correct calibration procedures are carefully followed. A comparable accuracy can be achieved off-centerline with carefully designed, conventional probes, except near Mach 1. In the range 0.95 less than M less than 1.05, the laser Doppler velocimeter appears to offer the most promise for improved calibration accuracy off-centerline.

  15. Systems tunnel linear shaped charge lightning strike

    NASA Technical Reports Server (NTRS)

    Cook, M.

    1989-01-01

    Simulated lightning strike testing of the systems tunnel linear shaped charge (LSC) was performed at the Thiokol Lightning Test Complex in Wendover, Utah, on 23 Jun. 1989. The test article consisted of a 160-in. section of the LSC enclosed within a section of the systems tunnel. The systems tunnel was bonded to a section of a solid rocket motor case. All test article components were full scale. The systems tunnel cover of the test article was subjected to three discharges (each discharge was over a different grounding strap) from the high-current generator. The LSC did not detonate. All three grounding straps debonded and violently struck the LSC through the openings in the systems tunnel floor plates. The LSC copper surface was discolored around the areas of grounding strap impact, and arcing occurred at the LSC clamps and LSC ends. This test verified that the present flight configuration of the redesigned solid rocket motor systems tunnel, when subjected to simulated lightning strikes with peak current levels within 71 percent of the worst-case lightning strike condition of NSTS-07636, is adequate to prevent LSC ignition. It is therefore recommended that the design remain unchanged.

  16. PUREX Storage Tunnels dangerous waste permit application

    SciTech Connect

    Not Available

    1990-09-01

    The Hanford Site is operated by the US Department of Energy-Richland Operations Office. The PUREX Storage Tunnels are a storage unit located on the Hanford Site. The unit consists of two earth-covered railroad tunnels that are used for storage of process equipment (some containing dangerous waste) removed from the PUREX Plant. Radioactively contaminated equipment is loaded on railroad cars and remotely transferred into the tunnels for long-term storage. Westinghouse Hanford Company is a major contractor to the US Department of Energy-Richland Operations Office and serves as a co-operator of the PUREX Storage Tunnels, the waste management unit addressed by this permit application. The PUREX Storage Tunnels Dangerous Waste Permit Application (Revision O) consists of both a Part A and Part B permit application and is based on information available as of August 31, 1990. An explanation of the Part A revision submitted with this document is provided at the beginning of the Part A section. In this Part A revision, the PUREX Storage Tunnels have been redesignated as a miscellaneous unit. The Part B consists of 15 chapters addressing the organization and content of the Part B checklist prepared by the Washington State Department of Ecology.

  17. The Leadville Mine Drainage Tunnel Catastrophe: A Case Study of How Isotope Geochemistry Provided Forensic Evidence to Inform Policy Decisions

    NASA Astrophysics Data System (ADS)

    Williams, M. W.; Wireman, M.; Liu, F.; Gertson, J.

    2008-12-01

    A state of emergency was declared in February 2008 because of fears that a blocked drainage tunnel in the Leadville mining district of Colorado could cause a catastrophic flood. An estimated 1 billion gallons of metals-laden water poses an eminent threat to the city of Leadville and the headwaters of the Arkansas river. Within days of the declaration of a state of emergency, Governor Ritter and Senator Salazer of Colorado, along with a host of other local and statewide politicians, visited the site and emphasized the need to develop a fast yet safe mitigation plan. Here we provide information from a case study that illustrates how a suite of isotopic and hydrologic tools enables identification of critical, site-specific variables essential in developing a science plan to guide targeted remediation of the Leadville drainage tunnel. The isotopic tools, including both stable and radiogenic isotopes, provided clear and compelling evidence of water sources and flowpaths in an area that has undergone extensive perturbations, including the drilling of more than 2,000 mine shafts. This forensic evidence was the key information in developing a plan to plug the drainage tunnel several hundred feet underground, divert a major source of polluted water from reaching the collapsed tunnel and piping it to an existing treatment plant, and guidance on where to place pumps in additional mine shafts, and the drilling of new wells to pump water in case the plugging of the tunnel caused water to pool up and raise the water table to dangerous heights. This particular case of forensic hydrology using isotopic tools not only provides the scientific basis for an operational plan to defuse a life- and property-threatening situation, it also provides the basis for decommissioning an existing water treatment plant, which will result in savings of over 1 million annually in operational costs. Decommissioning the existing water treatment plant will pay for the tunnel mitigation within several

  18. Tunneling and tunneling switching dynamics in phenol and its isotopomers from high-resolution FTIR spectroscopy with synchrotron radiation.

    PubMed

    Albert, Sieghard; Lerch, Philippe; Prentner, Robert; Quack, Martin

    2013-01-02

    Tunneling and chemical reactions by tunneling switching are reported for phenol and ortho-deuterophenol on the basis of high-resolution FTIR spectroscopy. Tunneling splittings are measured for the torsional motion in the ground and several vibrationally excited states of phenol. Tunneling times range from 10 ns to 1 ps, depending on excitation. For more-highly excited torsional levels in ortho-deuterophenol, delocalization and chemical reaction by tunneling switching is found.

  19. 33 CFR 110.168 - Hampton Roads, Virginia and adjacent waters (Datum: NAD 83).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Bay, Thimble Shoals Channel Anchorages. (i) Anchorage B . The waters bounded by a line connecting the... Bridge Tunnel or Monitor-Merrimac Bridge Tunnel (MMBT) must be capable of getting underway within 30 minutes with sufficient power to keep free of the bridge tunnel complex. (15) A vessel may not anchor...

  20. 33 CFR 110.168 - Hampton Roads, Virginia and adjacent waters (Datum: NAD 83).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Bay, Thimble Shoals Channel Anchorages. (i) Anchorage B . The waters bounded by a line connecting the... Bridge Tunnel or Monitor-Merrimac Bridge Tunnel (MMBT) must be capable of getting underway within 30 minutes with sufficient power to keep free of the bridge tunnel complex. (15) A vessel may not anchor...

  1. 33 CFR 110.168 - Hampton Roads, Virginia and adjacent waters (Datum: NAD 83).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Bay, Thimble Shoals Channel Anchorages. (i) Anchorage B . The waters bounded by a line connecting the... Bridge Tunnel or Monitor-Merrimac Bridge Tunnel (MMBT) must be capable of getting underway within 30 minutes with sufficient power to keep free of the bridge tunnel complex. (15) A vessel may not anchor...

  2. Theory of dissociative tunneling ionization

    NASA Astrophysics Data System (ADS)

    Svensmark, Jens; Tolstikhin, Oleg I.; Madsen, Lars Bojer

    2016-05-01

    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 of 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 fields, where the BO approximation does not apply, the weak-field asymptotic theory describes the spectrum accurately.

  3. Luminescent barometry in wind tunnels

    NASA Technical Reports Server (NTRS)

    Kavandi, Janet; Callis, James; Gouterman, Martin; Khalil, Gamal; Wright, Daniel; Green, Edmond; Burns, David; Mclachlan, Blair

    1990-01-01

    A flexible and relatively inexpensive method and apparatus are described for continuous pressure mapping of aerodynamic surfaces using photoluminescence and imaging techniques. Platinum octaethylporphyrin (PtOEP) has a phosphorescence known to be quenched by oxygen. When dissolved in a silicone matrix, PtOEP may be distributed over a surface as a thin, uniform film. When the film is irradiated with ultraviolet light, the luminescence intensity provides a readily detectable, qualitative surface flow visualization. Moreover, since the luminescence intensity is found to be inversely proportional to the partial pressure of oxygen, a quantitative measure of pressure change may be obtained using a silicon target vidicon or a charge-coupled device video sensor to measure intensity. Luminescent images are captured by a commercial frame buffer board. Images taken in wind tunnels during airflow are ratioed to images taken under ambient 'wind-off' conditions. The resulting intensity ratio information is converted to pressure using calibration curves of I0/I vs p/p0, where I0 is the intensity at ambient pressure p0 and I is the intensity at any other pressure p.

  4. Full-Scale Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Construction of Full-Scale Tunnel (FST) balance. Smith DeFrance described the 6-component type balance in NACA TR No. 459 (which also includes a schematic diagram of the balance and its various parts). 'Ball and socket fittings at the top of each of the struts hod the axles of the airplane to be tested; the tail is attached to the triangular frame. These struts are secured to the turntable, which is attached to the floating frame. This frame rests on the struts (next to the concrete piers on all four corners), which transmit the lift forces to the scales (partially visible on the left). The drag linkage is attached to the floating frame on the center line and, working against a known counterweight, transmits the drag force to the scale (center, face out). The cross-wind force linkages are attached to the floating frame on the front and rear sides at the center line. These linkages, working against known counterweights, transmit the cross-wind force to scales (two front scales, face in). In the above manner the forces in three directions are measured and by combining the forces and the proper lever arms, the pitching, rolling, and yawing moments can be computed. The scales are of the dial type and are provided with solenoid-operated printing devices. When the proper test condition is obtained, a push-button switch is momentarily closed and the readings on all seven scales are recorded simultaneously, eliminating the possibility of personal errors.'

  5. Tunneling and Transport in Nanowires

    SciTech Connect

    Goldman, Allen M.

    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.

  6. 8-Foot High Speed Tunnel

    NASA Technical Reports Server (NTRS)

    1936-01-01

    Control panel below the test section of the 8-Foot High Speed Tunnel (8-Foot HST). Authorized July 17, 1933, construction of the 8-Foot HST was paid for with funds from the Federal Public Works Administration. Manly Hood and Russell Robinson designed the unusual facility which could produce a 500 mph wind stream across an 8-Foot test section. The concrete shell was not part of the original design. Like most projects funded through New Deal programs, the PWA restricted the amount of money which could be spent on materials. The majority of funds were supposed to be expended on labor. Though originally, Hood and Robinson had planned a welded steel pressure vessel around the test section, PWA officials proposed the idea of concrete. This picture shows the test section inside the igloo-like structure with walls of 1-foot thick reinforced concrete. The thick walls were needed 'because of the Bernoulli effect, [which meant that] the text chamber had to withstand powerful, inwardly directed pressure. Operating personnel located inside the igloo were subjected to pressures equivalent to 10,000-foot altitude and had to wear oxygen masks and enter through airlocks. A heat exchanger removed the large quantities of heat generated by the big fan.'

  7. Propeller Design Optimization for Tunnel Bow Thrusters in the Bollard Pull Condition

    DTIC Science & Technology

    2012-06-01

    intrusions into the propeller tunnel which tend to block fluid flow. It requires, however, specialized bearings that currently remain in experimental...cable to provide control power to the motor. 4. Red 2-wire (twisted pair) connection to water intrusion alarm. 5. Black 8-wire cable for sensor...leaks. A leak test conducted upon return showed no water intrusion had occurred overnight. 1 Raw

  8. Quantum tunneling during interstellar surface-catalyzed formation of water: the reaction H + H2O2 → H2O + OH† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6cp06457d Click here for additional data file.

    PubMed Central

    Samanta, Pradipta Kumar; Köhn, Andreas; Kästner, Johannes

    2016-01-01

    The final step of the water formation network on interstellar grain surfaces starting from the H + O2 route is the reaction between H and H2O2. 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 + H2O2 → H2O + OH, but also for H + H2O2 → H2 + HO2. We find a branching ratio where the title reaction is favored by at least two orders of magnitude at 114 K. In the interstellar medium this reaction predominantly occurs on water surfaces, which increases the probability that the two reactants meet. To mimic this, one, two, or three spectator H2O molecules are added to the system. Eley–Rideal bimolecular and Langmuir–Hinshelwood unimolecular rate constants are presented here. The kinetic isotope effects for the various cases are compared to experimental data as well as to expressions commonly used in astrochemical models. Both the rectangular barrier and the Eckart approximations lead to errors of about an order of magnitude. Finally, fits of the rate constants are provided as input for astrochemical models. PMID:27886292

  9. A Method for Dynamic Risk Assessment and Management of Rockbursts in Drill and Blast Tunnels

    NASA Astrophysics Data System (ADS)

    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).

  10. Metals removal from an acid mine drainage: The Argo Tunnel experience

    SciTech Connect

    Cevaal, J.N.; Abel, R.J.; Rogers, S.E.

    1996-12-31

    The abandoned Argo Tunnel, located approximately 30 miles west of Denver in Idaho Springs, Colorado, is part of the Clear Creek/Central City Superfund Site and was identified as the most significant source of metals contamination to Clear Creek. More than 740 pounds of metals (including iron, manganese, zinc, copper and aluminum) are discharged from the Argo each day. During the course of bench-scale testing and preliminary design of the chemical precipitation treatment facility for the Argo Tunnel acid mine drainage, three treatment processes: conventional chemical precipitation, {open_quotes}high density sludge{close_quotes} precipitation arid membrane separation; and four chemical reagents: hydrated lime, caustic, magnesium hydroxide, and lime plus soda ash were evaluated. The result was the prepurchase of a {open_quotes}high density sludge{close_quotes} precipitation process using caustic as the reagent. The process was sized to treat the design average flow rate from the tunnel with additional capacity for potential future groundwater flows and for most surge events. The treatment facility was sited at the Argo Tunnel portal and adjacent to the Argo Mill, which is listed on the National Register of Historic Places. The nearby historic designation and strong local mining heritage led to null styled superstructure encompassing indigenous mining architecture. Improvements to the water quality within the basin include removal of most of the 740 pounds of metals the tunnel currently discharges to Clear Creek and a significant reduction in instream metal concentrations, notably zinc, manganese and copper.

  11. Heart disease mortality among bridge and tunnel officers exposed to carbon monoxide

    SciTech Connect

    Stern, F.B.; Halperin, W.E.; Hornung, R.W.; Ringenburg, V.L.; McCammon, C.S.

    1988-12-01

    The authors investigated the effect of occupational exposure to carbon monoxide on mortality from heart disease in a retrospective study of 5,529 New York City bridge and tunnel officers employed between January 1, 1952 and February 10, 1981, at any one of nine major water crossings operated by the Triborough Bridge and Tunnel Authority of New York City. Among former tunnel officers, 61 deaths from arteriosclerotic heart disease were observed, as compared with 45 expected (standardized mortality ratio = 1.35, 90% confidence interval 1.09-1.68); expected rates were based on the New York City population. Using a proportional hazards model, the authors compared the risk of mortality from arteriosclerotic heart disease among tunnel officers with that of the less-exposed bridge officers. No association of arteriosclerotic heart disease with length of exposure was observed, but there was significant interaction of exposure with age. The elevated risk of arteriosclerotic heart disease among tunnel officers, as compared with that of bridge officers, declined after cessation of exposure, with much of the risk dissipating within as little as five years. The parallel findings of this study of occupational exposure to carbon monoxide and those studies showing the relation of cigarette smoking to cardiovascular mortality suggest that carbon monoxide may play an important role in the pathophysiology of cardiovascular mortality associated with cigarette smoking.

  12. Health and safety evaluation of a modified tunnel borer design for application to single entry coal mine development

    NASA Technical Reports Server (NTRS)

    Zimmerman, W. F.

    1982-01-01

    A health and safety analysis of a single entry coal tunnel borer system is given. The results of the health analysis indicated that while the tunnel borer design offered improvements in dust control through the use of water sprays, a higher face ventilation rule, and the application of spalling rather than the conventional grinding process, it interjected an additional mutagen and toxic compound into the environment through the use of shotcrete. The tunnel borer system easily conformed with the prescribed fatality limit, but exceeded the required limits for disabling and overall injuries. It also exhibited projected disabling and overall injury rates considerably higher than existing continuous mining injury rates. Consequently, the tunnel borer system was not considered an advanced system.

  13. Airborne asbestos fibres monitoring in tunnel excavation.

    PubMed

    Gaggero, Laura; Sanguineti, Elisa; Yus González, Adrián; Militello, Gaia Maria; Scuderi, Alberto; Parisi, Giovanni

    2017-04-03

    Tunnelling across ophiolitic formation with Naturally Occurring Asbestos (NOA) can release fibres into the environment, exposing workers, and the population, if fibres spread outside the tunnel, leading to increased risk of developing asbestos-related disease. Therefore, a careful plan of environmental monitoring is carried out during Terzo Valico tunnel excavation. In the present study, data of 1571 samples of airborne dust, collected between 2014 and 2016 inside the tunnels, and analyzed by SEM-EDS for quantification of workers exposure, are discussed. In particular, the engineering and monitoring management of 100 m tunnelling excavation across a serpentinite lens (Cravasco adit), intercalated within calcschists, is reported. At this chrysotile occurrence, 84% of 128 analyzed samples (from the zone closer to the front rock) were above 2 ff/l. However, thanks to safety measures implemented and tunnel compartmentation in zones, the asbestos fibre concentration did not exceed the Italian standard of occupational exposure (100 ff/l) and 100% of samples collected in the outdoor square were below 1 ff/l. During excavation under normal working conditions, asbestos concentrations were below 2 ff/l in 97.4% of the 668 analyzed samples. Our results showed that air monitoring can objectively confirm the presence of asbestos minerals at a rock front in relative short time and provide information about the nature of the lithology at the front. The present dataset, the engineering measures described and the operative conclusions are liable to support the improvement of legislation on workers exposure to asbestos referred to the tunnelling sector, lacking at present.

  14. Development of the tunneling junction simulation environment for scanning tunneling microscope evaluation

    NASA Astrophysics Data System (ADS)

    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.

  15. Mitigation of the surficial hydrogeological impact induced by the construction of the Pajares Tunnels (NW Spain).

    NASA Astrophysics Data System (ADS)

    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).

  16. Wind Tunnel Aerodynamic Characteristics of a Transport-type Airfoil in a Simulated Heavy Rain Environment

    NASA Technical Reports Server (NTRS)

    Bezos, Gaudy M.; Dunham, R. Earl, Jr.; Gentry, Garl L., Jr.; Melson, W. Edward, Jr.

    1992-01-01

    The effects of simulated heavy rain on the aerodynamic characteristics of an NACA 64-210 airfoil section equipped with leading-and trailing-edge high-lift devices were investigated in the Langley 14- by 22-Foot Subsonic Tunnel. The model had a chord of 2.5 ft, a span of 8 ft, and was mounted on the tunnel centerline between two large endplates. Aerodynamic measurements in and out of the simulated rain environment were obtained for dynamic pressures of 30 and 50 psf and an angle-of-attack range of 0 to 20 degrees for the cruise configuration. The rain intensity was varied to produce liquid water contents ranging from 16 to 46 gm/cu m. The results obtained for various rain intensity levels and tunnel speeds showed significant losses in maximum lift capability and increases in drag for a given lift as the liquid water content was increased. The results obtained on the landing configuration also indicate a progressive decrease in the angle of attack at which maximum lift occurred and an increase in the slope of the pitching-moment curve as the liquid water content was increased. The sensitivity of test results to the effects of the water surface tension was also investigated. A chemical was introduced into the rain environment that reduced the surface tension of water by a factor of 2. The reduction in the surface tension of water did not significantly alter the level of performance losses for the landing configuration.

  17. Modelling of interband transitions in GaAs tunnel diode

    NASA Astrophysics Data System (ADS)

    Louarn, K.; Fontaine, C.; Arnoult, A.; Olivié, F.; Lacoste, G.; Piquemal, F.; Bounouh, A.; Almuneau, G.

    2016-06-01

    In this paper, an improved model for non-local band-to-band tunneling carrier transport is presented and compared to experimental measurement from GaAs tunnel junctions devices. By carefully taking into account the coupling between the conduction band and the light holes valence band, the model is able to predict, with realistic material parameters, the amplitude of the current density throughout the whole tunneling regime. The model suggests that elastic band-to-band tunneling instead of trap-assisted-tunneling is the predominant mechanism in GaAs tunnel junctions, which is of great interest for better understanding and improving III-V multi-junction solar cells.

  18. 8-Foot High Speed Tunnel (HST

    NASA Technical Reports Server (NTRS)

    1957-01-01

    Interior view of the slotted throat test section installed in the 8-Foot High Speed Tunnel (HST) in 1950. The slotted region is about 160 inches in length. In this photograph, the sting-type model support is seen straight on. In a NASA report, the test section is described as follows: 'The test section of the Langley 8-foot transonic tunnel is dodecagonal in cross section and has a cross-sectional area of about 43 square feet. Longitudinal slots are located between each of the 12 wall panels to allow continuous operation through the transonic speed range. The slots contain about 11 percent of the total periphery of the test section. Six of the twelve panels have windows in them to allow for schlieren observations. The entire test section is enclosed in a hemispherical shaped chamber.' John Becker noted that the tunnel's 'final achievement was the development and use in routine operations of the first transonic slotted throat. The investigations of wing-body shapes in this tunnel led to Whitcomb's discovery of the transonic area rule.' James Hansen described the origins of the the slotted throat as follows: 'In 1946 Langley physicist Ray H. Wright conceived a way to do transonic research effectively in a wind tunnel by placing slots in the throat of the test section. The concept for what became known as the slotted-throat or slotted-wall tunnel came to Wright not as a solution to the chronic transonic problem, but as a way to get rid of wall interference (i.e., the mutual effect of two or more meeting waves or vibrations of any kind caused by solid boundaries) at subsonic speeds. For most of the year before Wright came up with this idea, he had been trying to develop a theoretical understanding of wall interference in the 8-Foot HST, which was then being repowered for Mach 1 capability.' When Wright presented these ideas to John Stack, the response was enthusiastic but neither Wright nor Stack thought of slotted-throats as a solution to the transonic problem, only

  19. Practical anatomy of the carpal tunnel.

    PubMed

    Rotman, Mitchell B; Donovan, James P

    2002-05-01

    The carpal tunnel is most narrow at the level of the hook of the hamate. The median nerve is the most superficial structure. It has specific relationships to surrounding structures within the carpal tunnel to the ulnar bursa, flexor tendons, and endoscopic devices placed inside the canal. The importance of the ring finger axis is stressed. Knowledge of topographical landmarks that mark the borders of the carpal tunnel, the hook of the hamate, superficial arch, and thenar branch of the median nerve ensure appropriate incision placement for endoscopic as well as open carpal tunnel release surgery. Anatomy of the transverse carpal ligament, its layers and relationships to adjacent structures including the fad pad, Guyon's canal, palmar fascia, and thenar muscles has been discussed. Fibers derived primarily from thenar muscle fascia with connections to the hypothenar muscle fascia and dorsal fascia of the palmaris brevis form a separate fascial layer directly palmar to the TCL and can be retained. This helps to preserve postoperative pinch strength. The fat pad in line with the ring finger axis overlaps the deep surface of the distal edge of the TCL and must be retracted in order to visualize the distal end of the ligament. Whereas the ulnar artery within Guyon's canal is frequently located radial to the hook of the hamate, injury to this structure has not been a problem during ECTR surgery. Variations of the median nerve and its branches, as well as the palmar cutaneous nerve distribution, have been reviewed. A rare ulnar-sided thenar branch from the median nerve, interconnecting branches between the ulnar and median nerves located just distal to the end of the TCL, and transverse ulnar-based cutaneous nerves can be injured during open or ECTR surgery. Anomalous muscles, tendons or interconnections, and the lumbricals during finger flexion may be seen within the carpal tunnel. These structures can be the cause of compression of the median nerve. The anatomy of the

  20. Fiber-optic-based laser vapor screen flow visualization system for aerodynamic research in larger scale subsonic and transonic wind tunnels

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.; Inenaga, Andrew S.

    1994-01-01

    Laser vapor screen (LVS) flow visualization systems that are fiber-optic based were developed and installed for aerodynamic research in the Langley 8-Foot Transonic Pressure Tunnel and the Langley 7- by 10-Foot High Speed Tunnel. Fiber optics are used to deliver the laser beam through the plenum shell that surrounds the test section of each facility and to the light-sheet-generating optics positioned in the ceiling window of the test section. Water is injected into the wind tunnel diffuser section to increase the relative humidity and promote condensation of the water vapor in the flow field about the model. The condensed water vapor is then illuminated with an intense sheet of laser light to reveal features of the flow field. The plenum shells are optically sealed; therefore, video-based systems are used to observe and document the flow field. Operational experience shows that the fiber-optic-based systems provide safe, reliable, and high-quality off-surface flow visualization in smaller and larger scale subsonic and transonic wind tunnels. The design, the installation, and the application of the Langley Research Center (LaRC) LVS flow visualization systems in larger scale wind tunnels are highlighted. The efficiency of the fiber optic LVS systems and their insensitivity to wind tunnel vibration, the tunnel operating temperature and pressure variations, and the airborne contaminants are discussed.