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Sample records for aedc vkf tunnel

  1. Results of tests using a 0.0125-scale model (70-QT) of the space shuttle vehicle orbiter in the AEDC VKF tunnel B (IA22), volume 2

    NASA Technical Reports Server (NTRS)

    Daileda, J. J.; Marroquin, J.

    1977-01-01

    Tabulated data of an experimental investigation are presented which was conducted in the AEDC/VKF Tunnel B to obtain interaction effects of RCS thruster jet plumes on SSV aerodynamics during staging to simulate RTLS abort. Interaction effects of the orbiter RCS thruster jet plumes on the orbiter and ET aerodynamics were investigated. RCS thruster jet plumes were simulated using both air and a 15 percent argon 85 percent helium gas mixture. The ET angle of attack range was -40 to +25 deg at sideslip angles of 0, 3, and 6 degrees. Orbiter angle of attack was varied from -15 to +10 degrees at sideslip angles of 0 and 3 deg. External tank full scale separation distances simulated were 0 to 1400 in. axially; 0 to 54 in. laterally; and a range of -100 to 1000 in. vertically. Data were also obtained on the ET in the interference-free flow field. Quiescent (no tunnel flow) thruster plume interaction data were obtained on the orbiter and orbiter-ET combination. Tests were conducted at Mach number 6 and a Reynolds number of 0.86 million per foot.

  2. Results of oil flow visualization tests of an 0.010-scale model (52-OT) of the space shuttle orbiter-tank mated and orbiter configurations in the AEDC VKF tunnel B (IA17B)

    NASA Technical Reports Server (NTRS)

    Daileda, J. J.

    1975-01-01

    An 0.010-scale model of the space shuttle (orbiter-tank mated and orbiter configurations) was tested in the AEDC VKF Tunnel B to investigate aerodynamic flow patterns. The tests utilized oil flow techniques to visualize the flow patterns. Tunnel free stream Mach number was 7.95 and nominal unit Reynolds number was 3.7 million per foot. Model angle of attack was varied from -5 deg through 10 deg and angle of sideslip was 0 deg and 2 deg. Photographs of resulting oil flow patterns are presented.

  3. Aerodynamic results of a separation effects test on a 0.01-scale model (52-OTS) of integrated SSV in the AEDC/VKF 40-by-40 inch supersonic wind tunnel A, volume 1

    NASA Technical Reports Server (NTRS)

    Campbell, J. H., II

    1975-01-01

    Experimental aerodynamic investigations were conducted, during the period July 18-19, 1974, in the AEDC/VKF Tunnel A facility on a 0.01-scale model (52-OTS) of the integrated space shuttle vehicle, including only one SRB. The purpose of the investigation was to obtain data for close-in proximity (SRB to orbiter/tank) effects with the orbiter/tank combination at relatively high alpha and beta attitudes, and with the SRB separation motors off. The AEDC Captive Trajectory System (CTS), which supported the SRB, was used in conjunction with the tunnel primary sector (supporting the orbiter/tank) to obtain grid type separation effects data. The one symmetrical SRB model was used interchangeably to obtain both right-hand and left-hand SRB data. Free-stream data were also obtained for the orbiter/tank and for the SRB. This data was used to provide baselines for proximity effects. The entire investigation was conducted at a free-stream Mach number of 4.5 with unit Reynolds number ranging from 4.0 to 6.5 million per foot.

  4. Analysis of heat-transfer measurements from 2 AEDC wind tunnels on the Shuttle external tank

    NASA Technical Reports Server (NTRS)

    Nutt, K. W.

    1984-01-01

    Previous aerodynamic heating tests have been conducted in the AEDC/VKF Supersonic Wind Tunnel (A) to aid in defining the design thermal environment for the space shuttle external tank. The quality of these data has been under discussion because of the effects of low tunnel enthalpy and slow model injection rates. Recently the AEDC/VKF Hypersonic Wind Tunnel (C) has been modified to provide a Mach 4 capability that has significantly higher tunnel enthalpy with more rapid model injection rates. Tests were conducted in Tunnel C at Mach 4 to obtain data on the external tank for comparison with Tunnel A results. Data were obtained on a 0.0175 scale model of the Space Shuttle Integrated Vehicle at Re/ft = 4 x 10 to the 6th power with the tunnel stagnation temperature varying from 740 to 1440 R. Model attitude varied from an angle of attack of -5 to 5 deg and an angle of sideslip of -3 to 3 deg. One set of data was obtained in Tunnel C at Re/ft = 6.9 x 10 to the 6th for comparison with flight data. Data comparisons between the two tunnels for numerous regions on the external tank are given.

  5. Aerodynamic results of wind tunnel tests on a 0.010-scale model (32-QTS) space shuttle integrated vehicle in the AEDC VKF-40-inch supersonic wind tunnel (IA61)

    NASA Technical Reports Server (NTRS)

    Daileda, J. J.

    1976-01-01

    Plotted and tabulated aerodynamic coefficient data from a wind tunnel test of the integrated space shuttle vehicle are presented. The primary test objective was to determine proximity force and moment data for the orbiter/external tank and solid rocket booster (SRB) with and without separation rockets firing for both single and dual booster runs. Data were obtained at three points (t = 0, 1.25, and 2.0 seconds) on the nominal SRB separation trajectory.

  6. Results from a convective heat transfer rate distribution test on a 0.0175 scale model (22-0) of the Rockwell International vehicle 4 space shuttle configuration in the AEDC-VKF tunnel B (OH49B), volume 1

    NASA Technical Reports Server (NTRS)

    Herrera, B. J.

    1976-01-01

    The tests were conducted in a hypersonic wind tunnel at Mach number 8 to investigate reentry mode convective heat--transfer rates to the vehicle 4 shuttle orbiter. The thin skin thermocouple technique was used to obtain the heat transfer rate measurements. A complete set of tabulated data is presented.

  7. Results of tests in the AEDC VKF Tunnel B using the phase change paint technique on 0.04 scale 50 percent forebody models (82-0) of the Rockwell space shuttle orbiter (OH50A)

    NASA Technical Reports Server (NTRS)

    Quan, M.

    1976-01-01

    Model information and data from wind tunnel tests conducted on 0.04 scale 50 percent forebody models of the Space Shuttle Orbiter were presented. These tests were conducted using the phase change paint technique to determine aerodynamic heating rates due to various proturberances and recessions. Angles of attack from 20 deg through 45 deg were investigated at Mach 8.

  8. Aerodynamic results of a separation effects test on a 0.010-scale model (52-OTS) of the integrated SSV in the AEDC/VKF 40-by-40 inch supersonic wind tunnel A (IA111), volume 1

    NASA Technical Reports Server (NTRS)

    Chee, E.

    1976-01-01

    Graphical data obtained during experimental wind tunnel aerodynamic investigations of a 0.010 scale model (52-OTS) of the integrated space shuttle vehicle was presented. The purpose of this investigation was to obtain data with the solid rocket booster (SRB) in proximity to the orbiter/external tank (O/ET), over a large O/ET initial angle of attack and sideslip range, as well as data on the SRB alone (greatly separated from the O/ET). A captive trajectory system, which supported the SRB, was used with the tunnel primary sector (supporting the O/ET) to obtain grid type separation effects data. One symmetrical SRB model was used interchangeably to obtain right-hand and left-hand SRB data. The entire investigation was conducted at a free-stream Mach number of 4.5 at unit Reynolds number of 3.95 and 5.9 million per foot.

  9. Aerodynamic results of a separation effects test on a 0.010-scale model (52-OTS) of the integrated SSV in the AEDC/VKF 40-by-40 inch supersonic wind tunnel A (IA111), volume 2

    NASA Technical Reports Server (NTRS)

    Chee, E.

    1976-01-01

    Tabular data obtained during experimental wind tunnel aerodynamic investigations of a 0.010 scale model (52-OTS) of the integrated space shuttle vehicle was presented. The purpose of this investigation was to obtain data with the solid rocket booster (SRB) in proximity to the orbiter/external tank (O/ET), over a large O/ET initial angle of attack and sideslip range, as well as data on the SRB alone (greatly separated from the O/ET). A captive trajectory system, which supported the SRB, was used with the tunnel primary sector (supporting the O/ET) to obtain grid type separation effects data. One symmetrical SRB model was used interchangeably to obtain right-hand and left-hand SRB data. The entire investigation was conducted at free-stream Mach number of 4.5 at unit Reynolds number of 3.95 and 5.9 million per foot.

  10. Results of investigations with an 0.015-scale model (49-0) of the Rockwell International space shuttle vehicle 140A/B configuration with modified OMS pods and elevons in the AEDC VKF tunnel B (0A79)

    NASA Technical Reports Server (NTRS)

    Esparza, V.; Lindsay, A. I.

    1975-01-01

    Aerodynamic data obtained from wind tunnel tests of an 0.015-scale space shuttle vehicle Orbiter model of a 140A/B configuration with modified orbital manuevering system pods and elevons are documented. Force data was obtained at various control surface settings and Reynolds numbers in the angle of attack range of 15 deg to 45 deg and at angles of sideslip of -5 deg to +5 deg. Control surface variables included elevon, rudder, speed brake, and body flap configurations.

  11. Continued Development of a Global Heat Transfer Measurement System at AEDC Hypervelocity Wind Tunnel 9

    NASA Technical Reports Server (NTRS)

    Kurits, Inna; Lewis, M. J.; Hamner, M. P.; Norris, Joseph D.

    2007-01-01

    Heat transfer rates are an extremely important consideration in the design of hypersonic vehicles such as atmospheric reentry vehicles. This paper describes the development of a data reduction methodology to evaluate global heat transfer rates using surface temperature-time histories measured with the temperature sensitive paint (TSP) system at AEDC Hypervelocity Wind Tunnel 9. As a part of this development effort, a scale model of the NASA Crew Exploration Vehicle (CEV) was painted with TSP and multiple sequences of high resolution images were acquired during a five run test program. Heat transfer calculation from TSP data in Tunnel 9 is challenging due to relatively long run times, high Reynolds number environment and the desire to utilize typical stainless steel wind tunnel models used for force and moment testing. An approach to reduce TSP data into convective heat flux was developed, taking into consideration the conditions listed above. Surface temperatures from high quality quantitative global temperature maps acquired with the TSP system were then used as an input into the algorithm. Preliminary comparison of the heat flux calculated using the TSP surface temperature data with the value calculated using the standard thermocouple data is reported.

  12. Aerodynamic results of wind tunnel separation tests on a 0.01-scale model (32-OTS) space shuttle integrated vehicle in the AEDC-VKF-SWTA (IA57)

    NASA Technical Reports Server (NTRS)

    Daileda, J. J.

    1974-01-01

    The integrated space shuttle vehicle was tested to determine proximity force and moment data for the orbiter/external tank and solid rocket booster (SRB) with and without separation rockets firing for both single and dual booster runs. Data were obtained at points t = 0 sec, t = 1.25 sec, and t = 2 sec on the nominal SRB separation trajectory.

  13. Experimental Investigation of Project Orion Crew Exploration Vehicle Aeroheating in AEDC Tunnel 9

    NASA Technical Reports Server (NTRS)

    Hollis, Brian R.; Horvath, Thomas J.; Berger, Karen T.; Lillard, Randolph P.; Kirk, Benjamin S.; Coblish, Joseph J.; Norris, Joseph D.

    2008-01-01

    An investigation of the aeroheating environment of the Project Orion Crew Entry Vehicle has been performed in the Arnold Engineering Development Center Tunnel 9. The goals of this test were to measure turbulent heating augmentation levels on the heat shield and to obtain high-fidelity heating data for assessment of computational fluid dynamics methods. Laminar and turbulent predictions were generated for all wind tunnel test conditions and comparisons were performed with the data for the purpose of helping to define uncertainty margins for the computational method. Data from both the wind tunnel test and the computational study are presented herein.

  14. Space shuttle SRB TPS protective paint test and evaluation in NASA Hot Gas Facility and AEDC Tunnel C

    NASA Technical Reports Server (NTRS)

    Karu, Z. S.

    1979-01-01

    The results and outcome of thermal tests conducted to evaluate the performance of the protective coat of paint on the solid rocket booster (SRB) thermal protection system are discussed. A problem was uncovered during a series of tests on the SRB instrumentation islands in AEDC Tunnel C on 13 January 1979. The white protective paint or the Turco coating on the thermal protection system panels began to flow soon after the panels were exposed to the flow. This presented a serious problem especially since the critical pressure sensing, parachute opening baroswitches located on the frustum of the SRB were most likely to be contaminated by the paint flowing down the sides of the SRB nose cone. Because the first two flight articles were already completed, it was necessary to find a solution to the existing paint problem. It was found that all the coatings tested, except the Hypalon, had similar undesirable flow characteristics. Also even the Hypalon, which did not flow, would bubble up and disintegrate when it was applied on top of the new Turco. Recently, the Turco coating was removed from an MSA-:11 panel by dissolving the paint with a certain agent. This was done in two ways, by dissolving and removing almost all of the paint on one side of the panel and dissolving and removing about 50% of the paint on the other. The panel was then coated with Hypalon and tested as before in the Hot Gas Facility. No evidence of any paint flow nor any adverse performance of MSA was observed.

  15. Pressure distributions obtained on a 0.10-scale model of the space shuttle Orbiter's forebody in the AEDC 16T propulsion wind tunnel

    NASA Technical Reports Server (NTRS)

    Siemers, P. M., III; Henry, M. W.

    1986-01-01

    Pressure distribution test data obtained on a 0.10-scale model of the forward fuselage of the Space Shuttle Orbiter are presented without analysis. The tests were completed in the AEDC 16T Propulsion Wind Tunnel. The 0.10-scale model was tested at angles of attack from -2 deg to 18 deg and angles of side slip from -6 to 6 deg at Mach numbers from 0.25 to 1/5 deg. The tests were conducted in support of the development of the Shuttle Entry Air Data System (SEADS). In addition to modeling the 20 SEADS orifices, the wind-tunnel model was also instrumented with orifices to match Development Flight Instrumentation (DFI) port locations that existed on the Space Shuttle Orbiter Columbia (OV-102) during the Orbiter Flight Test program. This DFI simulation has provided a means of comparisons between reentry flight pressure data and wind-tunnel and computational data.

  16. Flight and wind-tunnel correlation of boundary-layer transition on the AEDC transition cone

    NASA Technical Reports Server (NTRS)

    Fisher, D. L.; Dougherty, N. S., Jr.

    1982-01-01

    Transition and fluctuating surface pressure data were acquired on a 10 deg included angle cone, using the same instrumentation and technique over a wide range of Mach and Reynolds numbers in 23 wind tunnels and in flight. Transition was detected with a traversing pitot-pressure probe in contact with the surface. The surface pressure fluctuations were measured with microphones set flush in the cone surface. Good correlation of end of transition Reynolds number RE(T) was obtained between data from the lower disturbance wind tunnels and flight up to a boundary layer edge Mach number, M(e) = 1.2. Above M(e) = 1.2, however, this correlation deteriorates, with the flight Re(T) being 25 to 30% higher than the wind tunnel Re(T) at M(e) = 1.6. The end of transition Reynolds number correlated within + or - 20% with the surface pressure fluctuations, according to the equation used. Broad peaks in the power spectral density distributions indicated that Tollmien-Schlichting waves were the probable cause of transition in flight and in some of the wind tunnels.

  17. Differential elevon effectiveness lateral control optimization and elevon hinge moment investigation on a 0.015 scale space shuttle orbiter model 49-0 (140A/B/C modified) in the AECD VKF wind tunnel A (0A115)

    NASA Technical Reports Server (NTRS)

    Esparza, V.

    1975-01-01

    Experimental aerodynamic investigations were conducted in the Arnold Engineering Development Center (AEDC) Von Karman Facility Tunnel A on a scale model of the space shuttle orbiter. The objectives of this test were: (1) determine supersonic differential elevon/aileron lateral control optimization, (2) determine supersonic elevon hinge moments, (3) determine the supersonic effects of the new baseline 6-inch elevon/elevon and elevon/fuselage gaps, and 4) determine the supersonic effects of the new short (VL70-008410) OMS pods. Six-component aerodynamic force, moment, and elevon hinge moment data were recorded.

  18. Results of aeroheating DFI and ET design-data test on a 0.0175-scale model 60-OTS conducted in the Von Karman Gas Dynamics Facility (VKF) 40" supersonic and the 50" hypersonic wind tunnels A and C

    NASA Technical Reports Server (NTRS)

    Marroquin, J.; Leef, C. R.

    1985-01-01

    The 0.0175-scale thin-skin thermocouple Model 60-OTS was tested in the von Karman Gas Facility 40-inch continuous flow supersonic tunnel A and the VKF Tunnel C. Testing was conducted at Mach numbers 2.25 to 4.0, and Reynolds numbers from 0.4 x 10 to the 6th power/ft to 6.6 x 10 to the 6th power/ft. Angle of attack range was from -5.0 to +5.0 degrees, and angle of sideslip range was from -6 to +6 degrees. The primary objective of this test was to provide a valid base for the external tank (ET) and solid rocket booster (SRB) heating prediction methodology for ascent flight by taking heating data at Development Flight Instrumentation (DFI) locations for flight conditions simulating STS-1 through -4. A second objective was to obtain additional aeroheating data to support potential reduction of the thermal protection system (TPS) on the ET. The third phase of the test was funded and conducted by NASA/MSFC for the purpose of establishing confidence in the data base from the lower temperature tunnel A.

  19. Results of tests of a Rockwell International space shuttle orbiter (-139 configuration) 0.0175-scale model (no. 29-0) in AEDC tunnel F to determine hypersonic heating effects (OH11)

    NASA Technical Reports Server (NTRS)

    Quan, M.

    1975-01-01

    Results from wind tunnel tests to determine hypersonic aerodynamic heating rates on a NASA/Rockwell Space Shuttle Orbiter are reported. The tests were to determine Mach number effects, if any, and to obtain overall heating rate data at high Mach numbers from 10.5 to 16. The model used was a 0.0175-scale model built to Rockwell Orbiter lines VL70-000139. The model identity number is 29-0. These tests, designated OH11, were conducted in the AEDC Tunnel F.

  20. Results of the space shuttle vehicle ascent air data system probe calibration test using a 0.07-scale external tank forebody model (68T) in the AEDC 16-foot transonic wind tunnel (IA-310), volume 1

    NASA Technical Reports Server (NTRS)

    Collette, J. G. R.

    1991-01-01

    A recalibration of the Space Shuttle Vehicle Ascent Air Data System probe was conducted in the Arnold Engineering Development Center (AEDC) transonic wind tunnel. The purpose was to improve on the accuracy of the previous calibration in order to reduce the existing uncertainties in the system. A probe tip attached to a 0.07-scale External Tank Forebody model was tested at angles of attack of -8 to +4 degrees and sideslip angles of -4 to +4 degrees. High precision instrumentation was used to acquire pressure data at discrete Mach numbers ranging from 0.6 to 1.55. Pressure coefficient uncertainties were estimated at less than 0.0020. Data is given in graphical and tabular form.

  1. Results of the space shuttle vehicle ascent air data system probe calibration test using a 0.07-scale external tank forebody model (68T) in the AEDC 16-foot transonic wind tunnel (IA-310), volume 2

    NASA Technical Reports Server (NTRS)

    Collette, J. G. R.

    1991-01-01

    A recalibration of the Space Shuttle Vehicle Ascent Air Data System probe was conducted in the Arnold Engineering and Development Center (AEDC) transonic wind tunnel. The purpose was to improve on the accuracy of the previous calibration in order to reduce the existing uncertainties in the system. A probe tip attached to a 0.07-scale External Tank Forebody model was tested at angles of attack of -8 to +4 degrees and sideslip angles of -4 to +4 degrees. High precision instrumentation was used to acquire pressure data at discrete Mach numbers ranging from 0.6 to 1.55. Pressure coefficient uncertainties were estimated at less than 0.0020. Additional information is given in tabular form.

  2. Results of phase change paint heat transfer tests utilizing 0.040 scale 50% forebody models (No. 82-0) of the Rockwell International space shuttle orbiter in AEDC VKF hypersonic tunnel B (test OH54A)

    NASA Technical Reports Server (NTRS)

    Dye, W. H.

    1976-01-01

    Results of aerodynamic heating tests conducted in October 1974 on a space shuttle orbiter model using the phase change paint technique are presented. The model was a 0.040 scale representation of the forward 50 percent of the orbiter. Surface roughness effects on boundary layer transition were investigated. Roughness was simulated by using steel balls varying in diameter from 0 (no balls) to 0.039 inch with 0.040 inch wide by 0.080 inch deep gaps. A nominal Mach number of 8 was tested with Reynolds number varying from 0.75 through 3.5 million per foot. Angle of attack was varied from 20 deg to 40 deg.

  3. Results of phase change paint heat transfer test utilizing 0.040-scale 50% forebody models (no. 82-0) of the Rockwell International Space Shuttle Orbiter in AEDC VKF hypersonic tunnel B (test OH54B)

    NASA Technical Reports Server (NTRS)

    Dye, W. H.

    1977-01-01

    Aerodynamic heating phase change paint tests for the space shuttle orbiter are reported. The model was a 0.040 scale representation of the forward 50% of the orbiter. Surface roughness effects on boundary layer transition were investigated. The roughness was simulated by steel balls 0.020 and 0.025 inch in diameter and a 0.25 in. diameter hole simulating the forward ET attach socket. A nominal Mach number of was tested with unit Reynolds number varying from 0.75 x 1 million ft through 3.5x 1 million ft. Angle of attack was varied from 20 degrees to 40 degrees.

  4. Results of an external tank separation test in AEDC/VKF tunnel B on 0.010-scale replica of space shuttle vehicle model 52-OT(IA17A), Volume 1

    NASA Technical Reports Server (NTRS)

    Spangler, R. H.; Daileda, J. J.

    1975-01-01

    Tests were conducted on scale models of the space shuttle orbiter and external tank (ET) to determine the aerodynamic interactions during a return to launch site abort separation. The orbiter model was built to vehicle 3 configuration lines (139B) and the ET model approximated the vehicle 5 configurations with protuberances and attach hardware. For these investigations the orbiter was mounted on the primary support system and the external tank was mounted on the captive trajectory system. Six-component data were obtained for each vehicle at various orbiter angles of attack and sideslip for a range of relative angular and linear displacements of the ET from the orbiter.

  5. Aero-optics measurement system for the AEDC aero-optics test facility

    NASA Astrophysics Data System (ADS)

    Crosswy, F. L.; Havener, A. G.

    1991-02-01

    A fundamental problem associated with hypersonic, endoatmospheric, optically guided vehicles for interception of ballistic reentry vehicles is target image degradation caused by the complex flow field of the intercept vehicle. The image degradation mechanisms are collectively referred to as aero-optics (AO) effects. The AEDC aero-optics measurement system provides the hardware, software, techniques, and expertise for measurement of the fundamental AO effects parameters in a ground test facility. The AO measurement system is presently configured for use in AEDC Tunnel C, a continuous flow hypersonic wind tunnel. AO effects measurements are based upon image analysis, image jitter, and holographic interferometry techniques. The primary purpose of this report is to provide hardware descriptions for the imaging and holography systems and their associated data acquisition and data reduction systems. Information is also provided in the appendixes, which describe several AO measurements technology advances in various stages of development.

  6. Heat transfer phase change paint tests of 0.0175-scale models (nos. 21-0 and 46-0) of the Rockwell International space shuttle orbiter in the AEDC tunnel B hypersonic wind tunnel (test OH25A)

    NASA Technical Reports Server (NTRS)

    Dye, W. H.

    1975-01-01

    Tests were conducted in a hypersonic wind tunnel using various truncated space shuttle orbiter configurations in an attempt to establish the optimum model size for other tests examining body shock-wing leading edge interference effects. The tests were conducted at Mach number 8 using the phase change paint technique. A test description, tabulated data, and tracings of isotherms made from photographs taken during the test are presented.

  7. Results of wind tunnel tests of an ASRM configured 0.03 scale Space Shuttle integrated vehicle model (47-OTS) in the AEDC 16-foot Transonic wind tunnel (IA613A), volume 1

    NASA Astrophysics Data System (ADS)

    Marroquin, J.; Lemoine, P.

    1992-10-01

    An experimental Aerodynamic and Aero-Acoustic loads data base was obtained at transonic Mach numbers for the Space Shuttle Launch Vehicle configured with the ASRM Solid Rocket Boosters as an increment to the current flight configuration (RSRB). These data were obtained during transonic wind tunnel tests (IA 613A) conducted in the Arnold Engineering Development Center 16-Foot transonic propulsion wind tunnel from March 27, 1991 through April 12, 1991. This test is the first of a series of two tests covering the Mach range from 0.6 to 3.5. Steady state surface static and fluctuating pressure distributions over the Orbiter, External Tank and Solid Rocket Boosters of the Shuttle Integrated Vehicle were measured. Total Orbiter forces, Wing forces and Elevon hinge moments were directly measured as well from force balances. Two configurations of Solid Rocket Boosters were tested, the Redesigned Solid Rocket Booster (RSRB) and the Advanced Solid Rocket Motor (ASRM). The effects of the position (i.e. top, bottom, top and bottom) of the Integrated Electronics Assembly (IEA) box, mounted on the SRB attach ring, were obtained on the ASRM configured model. These data were obtained with and without Solid Plume Simulators which, when used, matched as close as possible the flight derived pressures on the Orbiter and External Tank base. Data were obtained at Mach numbers ranging from 0.6 to 1.55 at a Unit Reynolds Number of 2.5 million per foot through model angles of attack from -8 to +4 degrees at sideslip angles of 0, +4 and -4 degrees.

  8. Results of wind tunnel tests of an ASRM configured 0.03 scale Space Shuttle integrated vehicle model (47-OTS) in the AEDC 16-foot transonic wind tunnel, volume 2

    NASA Astrophysics Data System (ADS)

    Marroquin, J.; Lemoine, P.

    1992-10-01

    An experimental Aerodynamic and Aero-Acoustic loads data base was obtained at transonic Mach numbers for the Space Shuttle Launch Vehicle configured with the ASRM Solid Rocket Boosters as an increment to the current flight configuration (RSRB). These data were obtained during transonic wind tunnel tests (IA 613A) conducted in the Arnold Engineering Development Center 16-Foot transonic propulsion wind tunnel from March 27, 1991 through April 12, 1991. This test is the first of a series of two tests covering the Mach range from 0.6 to 3.5. Steady state surface static and fluctuating pressure distributions over the Orbiter, External Tank and Solid Rocket Boosters of the Shuttle Integrated Vehicle were measured. Total Orbiter forces, Wing forces and Elevon hinge moments were directly measured as well from force balances. Two configurations of Solid Rocket Boosters were tested, the Redesigned Solid Rocket Booster (RSRB) and the Advanced Solid Rocket Motor (ASRM). The effects of the position (i.e., top, bottom, top and bottom) of the Integrated Electronics Assembly (IEA) box, mounted on the SRB attach ring, were obtained on the ASRM configured model. These data were obtained with and without Solid Plume Simulators which, when used, matched as close as possible the flight derived pressures on the Orbiter and External Tank base. Data were obtained at Mach numbers ranging from 0.6 to 1.55 at a Unit Reynolds Number of 2.5 million per foot through model angles of attack from -8 to +4 degrees at sideslip angles of 0, +4 and -4 degrees.

  9. Results of wind tunnel tests of an ASRM configured 0.03 scale Space Shuttle integrated vehicle model (47-OTS) in the AEDC 16-foot transonic wind tunnel, volume 2

    NASA Technical Reports Server (NTRS)

    Marroquin, J.; Lemoine, P.

    1992-01-01

    An experimental Aerodynamic and Aero-Acoustic loads data base was obtained at transonic Mach numbers for the Space Shuttle Launch Vehicle configured with the ASRM Solid Rocket Boosters as an increment to the current flight configuration (RSRB). These data were obtained during transonic wind tunnel tests (IA 613A) conducted in the Arnold Engineering Development Center 16-Foot transonic propulsion wind tunnel from March 27, 1991 through April 12, 1991. This test is the first of a series of two tests covering the Mach range from 0.6 to 3.5. Steady state surface static and fluctuating pressure distributions over the Orbiter, External Tank and Solid Rocket Boosters of the Shuttle Integrated Vehicle were measured. Total Orbiter forces, Wing forces and Elevon hinge moments were directly measured as well from force balances. Two configurations of Solid Rocket Boosters were tested, the Redesigned Solid Rocket Booster (RSRB) and the Advanced Solid Rocket Motor (ASRM). The effects of the position (i.e., top, bottom, top and bottom) of the Integrated Electronics Assembly (IEA) box, mounted on the SRB attach ring, were obtained on the ASRM configured model. These data were obtained with and without Solid Plume Simulators which, when used, matched as close as possible the flight derived pressures on the Orbiter and External Tank base. Data were obtained at Mach numbers ranging from 0.6 to 1.55 at a Unit Reynolds Number of 2.5 million per foot through model angles of attack from -8 to +4 degrees at sideslip angles of 0, +4 and -4 degrees.

  10. Results of wind tunnel tests of an ASRM configured 0.03 scale Space Shuttle integrated vehicle model (47-OTS) in the AEDC 16-foot Transonic wind tunnel (IA613A), volume 1

    NASA Technical Reports Server (NTRS)

    Marroquin, J.; Lemoine, P.

    1992-01-01

    An experimental Aerodynamic and Aero-Acoustic loads data base was obtained at transonic Mach numbers for the Space Shuttle Launch Vehicle configured with the ASRM Solid Rocket Boosters as an increment to the current flight configuration (RSRB). These data were obtained during transonic wind tunnel tests (IA 613A) conducted in the Arnold Engineering Development Center 16-Foot transonic propulsion wind tunnel from March 27, 1991 through April 12, 1991. This test is the first of a series of two tests covering the Mach range from 0.6 to 3.5. Steady state surface static and fluctuating pressure distributions over the Orbiter, External Tank and Solid Rocket Boosters of the Shuttle Integrated Vehicle were measured. Total Orbiter forces, Wing forces and Elevon hinge moments were directly measured as well from force balances. Two configurations of Solid Rocket Boosters were tested, the Redesigned Solid Rocket Booster (RSRB) and the Advanced Solid Rocket Motor (ASRM). The effects of the position (i.e. top, bottom, top and bottom) of the Integrated Electronics Assembly (IEA) box, mounted on the SRB attach ring, were obtained on the ASRM configured model. These data were obtained with and without Solid Plume Simulators which, when used, matched as close as possible the flight derived pressures on the Orbiter and External Tank base. Data were obtained at Mach numbers ranging from 0.6 to 1.55 at a Unit Reynolds Number of 2.5 million per foot through model angles of attack from -8 to +4 degrees at sideslip angles of 0, +4 and -4 degrees.

  11. Data report for tests on the heat transfer effects of the 0.0175 scale Rockwell International Space Shuttle Vehicle model 22-OT in the AEDC 50 inch B wind tunnel (0H4B), volume 1

    NASA Technical Reports Server (NTRS)

    Foster, T. F.; Grifall, W. J.; Martindale, W.

    1975-01-01

    Results of wind tunnel heat transfer tests of 0.0175-scale Rockwell International Space Shuttle Vehicle configurations for orbiter alone, tank alone, and orbiter plus external tank are presented. Body flap shielding of SSME's during simulated entry was investigated. The tests were conducted at Mach 8 for thirteen Reynolds number.

  12. Data report for tests on the heat transfer effects of the 0.0175-scale Rockwell International Space Shuttle Vehicle model 22-OT in the AEDC 50-inch B wind tunnel (OH4B), volume 3

    NASA Technical Reports Server (NTRS)

    Foster, T. F.; Grifall, W. J.; Martindale, W.

    1975-01-01

    Results of wind tunnel heat transfer tests of 0.0175-scale Rockwell International Space Shuttle Vehicle configurations for orbiter alone, tank alone, and orbiter plus external tank are presented. Body flap shielding of SSME's during simulated entry was also investigated. The tests were conducted at Mach 8 for thirteen Reynolds number per foot values ranging from 0.5 million to 3.72 million.

  13. Results of tests on a Rockwell International space shuttle orbiter (-139 configuration) 0.0175-scale model (no. 29-0) in AEDC tunnel B to determine boundary layer characteristics

    NASA Technical Reports Server (NTRS)

    Quan, M.

    1975-01-01

    Results of wind tunnel tests were conducted to determine boundary layer characteristics on the lower surface of a space shuttle orbiter. Total pressure and temperature profile data at various model stations were obtained using a movable, four-degree-of-freedom probe mechanism and static pressure taps on the model surface. During a typical run, the probe was located over a preselected model location, then driven down through the bondary layer until contact was made with the model surface.

  14. Results of an investigation of the space shuttle integrated vehicle aerodynamic heating characteristics obtained using the 0.0175-scale model 60-OTS in AEDC tunnel A during tests IH41 and IH41A

    NASA Technical Reports Server (NTRS)

    Cummings, J. W.; Dye, W. H.

    1977-01-01

    A thin skin thermocouple test was conducted to obtain heat-transfer data on the space shuttle integrated vehicle during the ascent phase of the flight profile. The test model was the 0.0175-scale thin skin thermocouple model (60-OTS) of the Rockwell International vehicle 5 configuration. The test was conducted at nominal Mach numbers of 2.5, 3.5, 4.5, and 5.5, and a free stream unit Reynolds number of 5 million per ft. Heat transfer data were obtained for angles of attack of 0, + or - 5, and 10 deg and yaw angles of 0, 3, and 6 deg. The integrated vehicle model was tested with the external tank configured with both a smooth ogive nose and an ogive nose with a spherical nose tip (nipple nose). The remainder of the test was conducted with the external tank installed alone in the tunnel.

  15. Scene projection technology development for imaging sensor testing at AEDC

    NASA Astrophysics Data System (ADS)

    Lowry, H.; Fedde, M.; Crider, D.; Horne, H.; Bynum, K.; Steely, S.; Labello, J.

    2012-06-01

    Arnold Engineering Development Center (AEDC) is tasked with visible-to-LWIR imaging sensor calibration and characterization, as well as hardware-in-the-loop (HWIL) testing with high-fidelity complex scene projection to validate sensor mission performance. They are thus involved in the development of technologies and methodologies that are used in space simulation chambers for such testing. These activities support a variety of program needs such as space situational awareness (SSA). This paper provides an overview of pertinent technologies being investigated and implemented at AEDC.

  16. Development of technologies for imaging sensor testing at AEDC

    NASA Astrophysics Data System (ADS)

    Lowry, H.; Fedde, M.; Crider, D.; Horne, H.; Gastineau, J.; Bynum, K.; Steely, S.; Labello, J.

    2011-06-01

    Arnold Engineering Development Center (AEDC) is involved in the development of technologies that enable hardwarein- the-loop (HWIL) testing with high-fidelity complex scene projection to validate sensor mission performance. Radiometric calibration with National Institute of Science and Technology (NIST) radiometers has improved radiometric and temporal fidelity testing in this cold background environment. This paper provides an overview of pertinent technologies being investigated and implemented at AEDC to support a variety of program needs such as HWIIL testing and space situational awareness (SSA).

  17. Process optimization and production kinetics for cellulase production by Trichoderma viride VKF3.

    PubMed

    Nathan, Vinod Kumar; Esther Rani, Mary; Rathinasamy, Gunaseeli; Dhiraviam, Kannan Narayanan; Jayavel, Sridhar

    2014-01-01

    Microbial cellulases are the enzymes widely studied due to their enormous applications in biochemical industry. Among 12 fungal isolates isolated from mangrove plant debris and soil sample collected from Valanthakad Mangroves, Kerala, India, 3 of them were found to exhibit cellulolytic activity. Among them, the most potent isolate which exhibited maximum cellulolytic activity was identified as Trichoderma viride VKF3 [Gene bank accession number- JX683684.1] based on colony morphology, microscopic observation and molecular centeracterization using D1/D2 region amplification. The isolate T. viride VKF3 was found to be non-phytopathogenic against the selected plants. Neighbour joining tree depicted its least divergence rate from the root taxon HM466686.1. T. viride VKF3 was grown under dynamic carbon, nitrogen sources, pH and temperature of the medium to draw out the optimum conditions for cellulase production. Protein stability kinetics and biomass production was also studied upto 11(th) day of incubation. It was evident from the study, that dextrose and beef extract could be used as major carbon and nitrogen sources in submerged fermentation at pH 9.0 and incubation temperature of 25°C to get maximum CMCase yield. Optimum enzyme recovery period was identified between 5(th) to 9(th) days of incubation beyond which the enzyme activity was reduced. By comparing two fermentation methods, submerged fermentation was found to be the best for maximum enzyme production. But utilization of substrates like sugarcane bagasse and cassava starch waste in the SSF offers a better scope in biodegradation of solid waste contributing to solid waste management. PMID:24600546

  18. Comparison of interference-free numerical results with sample experimental data for the AEDC wall-interference model at transonic and subsonic flow conditions

    NASA Technical Reports Server (NTRS)

    Newman, P. A.; Allison, D. O.

    1974-01-01

    Numerical results obtained from two computer programs recently developed with NASA support and now available for use by others are compared with some sample experimental data taken on a rectangular-wing configuration in the AEDC 16-Foot Transonic Tunnel at transonic and subsonic flow conditions. This data was used in an AEDC investigation as reference data to deduce the tunnel-wall interference effects for corresponding data taken in a smaller tunnel. The comparisons were originally intended to see how well a current state-of-the-art transonic flow calculation for a simple 3-D wing agreed with data which was felt by experimentalists to be relatively interference-free. As a result of the discrepancies between the experimental data and computational results at the quoted angle of attack, it was then deduced from an approximate stress analysis that the sting had deflected appreciably. Thus, the comparisons themselves are not so meaningful, since the calculations must be repeated at the proper angle of attack. Of more importance, however, is a demonstration of the utility of currently available computational tools in the analysis and correlation of transonic experimental data.

  19. Orbital Debris Assesment Tesing in the AEDC Range G

    NASA Technical Reports Server (NTRS)

    Polk, Marshall; Woods, David; Roebuck, Brian; Opiela, John; Sheaffer, Patti; Liou, J.-C.

    2015-01-01

    The space environment presents many hazards for satellites and spacecraft. One of the major hazards is hypervelocity impacts from uncontrolled man-made space debris. Arnold Engineering Development Complex (AEDC), The National Aeronautics and Space Administration (NASA), The United States Air Force Space and Missile Systems Center (SMC), the University of Florida, and The Aerospace Corporation configured a large ballistic range to perform a series of hypervelocity destructive impact tests in order to better understand the effects of space collisions. The test utilized AEDC's Range G light gas launcher, which is capable of firing projectiles up to 7 km/s. A non-functional full-scale representation of a modern satellite called the DebriSat was destroyed in the enclosed range enviroment. Several modifications to the range facility were made to ensure quality data was obtained from the impact events. The facility modifcations were intended to provide a high impact energy to target mass ratio (>200 J/g), a non-damaging method of debris collection, and an instrumentation suite capable of providing information on the physics of the entire imapct event.

  20. The AEDC aerospace chamber 7V: An advanced test capability for infrared surveillance and seeker sensors

    NASA Technical Reports Server (NTRS)

    Simpson, W. R.

    1994-01-01

    An advanced sensor test capability is now operational at the Air Force Arnold Engineering Development Center (AEDC) for calibration and performance characterization of infrared sensors. This facility, known as the 7V, is part of a broad range of test capabilities under development at AEDC to provide complete ground test support to the sensor community for large-aperture surveillance sensors and kinetic kill interceptors. The 7V is a state-of-the-art cryo/vacuum facility providing calibration and mission simulation against space backgrounds. Key features of the facility include high-fidelity scene simulation with precision track accuracy and in-situ target monitoring, diffraction limited optical system, NIST traceable broadband and spectral radiometric calibration, outstanding jitter control, environmental systems for 20 K, high-vacuum, low-background simulation, and an advanced data acquisition system.

  1. Measurements and computations of second-mode instability waves in three hypersonic wind tunnels.

    SciTech Connect

    Lewis, Daniel R.; Alba, Christopher R.; Rufer, Shann J.; Beresh, Steven Jay; Casper, Katya M.; Berridge, Dennis C.; Schneider, Steven P.

    2010-06-01

    High-frequency pressure-fluctuation measurements were made in AEDC Tunnel 9 at Mach 10 and the NASA Langley 15-Inch Mach 6 and 31-Inch Mach 10 tunnels. Measurements were made on a 7{sup o}-half-angle cone model. Pitot measurements of freestream pressure fluctuations were also made in Tunnel 9 and the Langley Mach-6 tunnel. For the first time, second-mode waves were measured in all of these tunnels, using 1-MHz-response pressure sensors. In Tunnel 9, second-mode waves could be seen in power spectra computed from records as short as 80 {micro}s. The second-mode wave amplitudes were observed to saturate and then begin to decrease in the Langley tunnels, indicating wave breakdown. Breakdown was estimated to occur near N {approx} 5 in the Langley Mach-10 tunnel. The unit-Reynolds-number variations in the data from Tunnel 9 were too large to see the same processes.

  2. Projection technologies for imaging sensor calibration, characterization, and HWIL testing at AEDC

    NASA Astrophysics Data System (ADS)

    Lowry, H. S.; Breeden, M. F.; Crider, D. H.; Steely, S. L.; Nicholson, R. A.; Labello, J. M.

    2010-04-01

    The characterization, calibration, and mission simulation testing of imaging sensors require continual involvement in the development and evaluation of radiometric projection technologies. Arnold Engineering Development Center (AEDC) uses these technologies to perform hardware-in-the-loop (HWIL) testing with high-fidelity complex scene projection technologies that involve sophisticated radiometric source calibration systems to validate sensor mission performance. Testing with the National Institute of Standards and Technology (NIST) Ballistic Missile Defense Organization (BMDO) transfer radiometer (BXR) and Missile Defense Agency (MDA) transfer radiometer (MDXR) offers improved radiometric and temporal fidelity in this cold-background environment. The development of hardware and test methodologies to accommodate wide field of view (WFOV), polarimetric, and multi/hyperspectral imaging systems is being pursued to support a variety of program needs such as space situational awareness (SSA). Test techniques for the acquisition of data needed for scene generation models (solar/lunar exclusion, radiation effects, etc.) are also needed and are being sought. The extension of HWIL testing to the 7V Chamber requires the upgrade of the current satellite emulation scene generation system. This paper provides an overview of pertinent technologies being investigated and implemented at AEDC.

  3. Pressure and heat flux results from the space shuttle/external fuel tank interaction test at Mach numbers 16 and 19

    NASA Technical Reports Server (NTRS)

    Brewer, E. B.; Haberman, D. R.

    1974-01-01

    Heat transfer rates and pressures were measured on a 0.0175-scale model of the space shuttle external tank (ET), model MCR0200. Tests were conducted with the ET model separately and while mated with a 0.0175-scale model of the orbiter, model 21-OT (Grumman). The tests were conducted in the AEDC-VKF Hypervelocity Wind Tunnel (F) at Mach numbers 16 and 19. The primary data consisted of the interaction heating rates experienced by the ET while mated with the orbiter in the flight configuration. Data were taken for a range of Reynolds numbers from 50,000 to 65,000 under laminar flow conditions.

  4. Aerodynamic Analyses and Database Development for Ares I Vehicle First Stage Separation

    NASA Technical Reports Server (NTRS)

    Pamadi, Bandu N.; Pei, Jing; Pinier, Jeremy T.; Klopfer, Goetz H.; Holland, Scott D.; Covell, Peter F.

    2011-01-01

    This paper presents the aerodynamic analysis and database development for first stage separation of Ares I A106 crew launch vehicle configuration. Separate 6-DOF databases were created for the first stage and upper stage and each database consists of three components: (a) isolated or freestream coefficients, (b) power-off proximity increments, and (c) power-on proximity increments. The isolated and power-off incremental databases were developed using data from 1% scaled model tests in AEDC VKF Tunnel A. The power-on proximity increments were developed using OVERFLOW CFD solutions. The database also includes incremental coefficients for one BDM and one USM failure scenarios.

  5. Technical issues in the development of scene-projection systems for sensor calibration, characterization, and HWIL testing at AEDC

    NASA Astrophysics Data System (ADS)

    Lowry, H. S.; Breeden, M. F.; Crider, D. H.; Steely, S. L.; Nicholson, R. A.; Labello, J. M.

    2008-04-01

    The characterization, calibration, and mission simulation testing of space-based, interceptor, and airborne sensors require a continual involvement in the development and evaluation of radiometric projection technologies. Recent efforts at the Arnold Engineering Development Center (AEDC) include hardware-in-the-loop (HWIL) testing with high-fidelity, complex scene projection technologies integrated into a low-cryovacuum (~20 K) environment as well as improvements in the radiometric source calibration systems. The latest scene simulation and projection technologies are being investigated, technologies that can produce desired target temperatures and target-to-sensor ranges that will make it possible to evaluate sensor mission performance. These technologies include multiple-band source subsystems and special spectral tailoring methods, as well as comprehensive analysis and optical properties measurements of the components involved. This paper discusses the implementation of such techniques at AEDC.

  6. Use Of Infrared Imagery In Continuous Flow Wind Tunnels

    NASA Astrophysics Data System (ADS)

    Stallings, D. W.; Whetsel, R. G.

    1983-03-01

    Thermal mapping with infrared imagery is a very useful test technique in continuous flow wind tunnels. Convective-heating patterns over large areas of a model can be obtained through remote sensing of the surface temperature. A system has been developed at AEDC which uses a commercially available infrared scanning camera to produce these heat-transfer maps. In addition to the camera, the system includes video monitors, an analog tape recording, an analog-to-digital converter, a digitizer control, and two minicomputers. This paper will describe the individual components, data reduction techniques, and typical applications. *

  7. Liquid Rocket Engine Testing - Historical Lecture: Simulated Altitude Testing at AEDC

    NASA Technical Reports Server (NTRS)

    Dougherty, N. S.

    2010-01-01

    The span of history covered is from 1958 to the present. The outline of this lecture draws from historical examples of liquid propulsion testing done at AEDC primarily for NASA's Marshall Space Flight Center (NASA/MSFC) in the Saturn/Apollo Program and for USAF Space and Missile Systems dual-use customers. NASA has made dual use of Air Force launch vehicles, Test Ranges and Tracking Systems, and liquid rocket altitude test chambers / facilities. Examples are drawn from the Apollo/ Saturn vehicles and the testing of their liquid propulsion systems. Other examples are given to extend to the family of the current ELVs and Evolved ELVs (EELVs), in this case, primarily to their Upper Stages. The outline begins with tests of the XLR 99 Engine for the X-15 aircraft, tests for vehicle / engine induced environments during flight in the atmosphere and in Space, and vehicle staging at high altitude. The discussion is from the author's perspective and background in developmental testing.

  8. Development and installation of a continuous water-monitoring system for the AEDC. Final report, Mar 92-May 92

    SciTech Connect

    Przybyciel, M.; Behm, J.; Sampey, T.

    1992-08-01

    A system to sample and analyze water from Rowland Creek at AEDC for hydrocarbon contaminants has been developed under a Small Business Innovation Research (SBIR) program contract. The online continuous water monitoring system involves the combination of two gas chromatographs (GC). The first instrument combines a gas/liquid sparger and a GC. The sparger uses an inert gas, helium, to remove and concentrate volatile organic chemicals which are then sequentially analyzed using a GC. The second gas chromatographic instrument involves the analysis of nonvolatile water samples through direct injection of water.

  9. Computational results for the effects of external disturbances on transition location of bodies of revolution from subsonic to supersonic speeds and comparisons with experimental data

    NASA Technical Reports Server (NTRS)

    Goradia, S. H.; Bobbitt, P. J.; Harvey, W. D.

    1989-01-01

    Computational experiments have been performed for a few configurations in order to investigate the effects of external flow disturbances on the extent of laminar flow and wake drag. Theoretical results have been compared with experimental data for the AEDC cone, for Mach numbers from subsonic to supersonic, and for both free flight and wind tunnel environments. The comparisons have been found to be very satisfactory, thus establishing the utility of the present method for the design and development of laminar flow configurations and for the assessment of wind tunnel data. In addition, results of calculations concerning the effects of unit Reynolds numbers on transition are presented. In addition to the AEDC cone, computations have been performed for an ogive body of revolution at zero angle of attack and supersonic Mach numbers. Results are presented for transition Reynolds number and wake drag for external disturbances corresponding to free air and the test section of the AEDC-VKF tunnel. These results have been found to compare quite well with wind tunnel data for cases when surface suction is applied as well as when suction is absent.

  10. Development of HWIL Testing Capabilities for Satellite Target Emulation at AEDC

    NASA Astrophysics Data System (ADS)

    Lowry, H.; Crider, D.; Burns, J.; Thompson, R.; Goldsmith, G., II; Sholes, W.

    Programs involved in Space Situational Awareness (SSA) need the capability to test satellite sensors in a Hardware-in-the-Loop (HWIL) environment. Testing in a ground system avoids the significant cost of on-orbit test targets and the resulting issues such as debris mitigation, and in-space testing implications. The space sensor test facilities at AEDC consist of cryo-vacuum chambers that have been developed to project simulated targets to air-borne, space-borne, and ballistic platforms. The 7V chamber performs calibration and characterization of surveillance and seeker systems, as well as some mission simulation. The 10V chamber is being upgraded to provide real-time target simulation during the detection, acquisition, discrimination, and terminal phases of a seeker mission. The objective of the Satellite Emulation project is to upgrade this existing capability to support the ability to discern and track other satellites and orbital debris in a HWIL capability. It would provide a baseline for realistic testing of satellite surveillance sensors, which would be operated in a controlled environment. Many sensor functions could be tested, including scene recognition and maneuvering control software, using real interceptor hardware and software. Statistically significant and repeatable datasets produced by the satellite emulation system can be acquired during such test and saved for further analysis. In addition, the robustness of the discrimination and tracking algorithms can be investigated by a parametric analysis using slightly different scenarios; this will be used to determine critical points where a sensor system might fail. The radiometric characteristics of satellites are expected to be similar to the targets and decoys that make up a typical interceptor mission scenario, since they are near ambient temperature. Their spectral reflectivity, emissivity, and shape must also be considered, but the projection systems employed in the 7V and 10V chambers should be

  11. Support technologies involved in the development and implementation of radiometric systems for sensor calibration, characterization, and HWIL testing at AEDC

    NASA Astrophysics Data System (ADS)

    Lowry, H. S.; Breeden, M. F.; Crider, D. H.; Steely, S. L.; Nicholson, R. A.; Labello, J. M.

    2009-05-01

    The characterization, calibration, and mission simulation testing of space-based, interceptor, and air-borne sensors require a continual involvement in the development and evaluation of radiometric projection technologies. Activities at Arnold Engineering Development Center (AEDC) include Hardware in the Loop (HWIL) testing with high-fidelity complex scene-projection technologies as well as improvements in the radiometric source-calibration systems. These technologies are integrated into a low cryo-vacuum (~20 K) environment. The latest scene simulation and HWIL projection technologies are being investigated that can produce desired target temperatures and target-to-sensor ranges such that sensor mission performance can be evaluated. These technologies include multiple-band source subsystems and special spectral-tailoring methods, as well as comprehensive analysis and optical properties measurements of the components involved. Emphasis areas include the development of methodologies to test wide field of view (WFOV), polarimetric, and multi/hyperspectral radiometric imaging systems.

  12. Measurements and Computations of Second-Mode Instability Waves in Three Hypersonic Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Berridge, Dennis C.; Casper, Katya M.; Rufer, Shann J.; Alba, Christopher R.; Lewis, Daniel R.; Beresh, Steven J.; Schneider, Steven P.

    2010-01-01

    High-frequency pressure-fluctuation measurements were made in AEDC Tunnel 9 at Mach 10 and the NASA Langley 15-Inch Mach 6 and 31-Inch Mach 10 tunnels. Measurements were made on a 7deg-half-angle cone model. Pitot measurements of freestream pressure fluctuations were also made in Tunnel 9 and the Langley Mach-6 tunnel. For the first time, second-mode waves were measured in all of these tunnels, using 1-MHz-response pressure sensors. In Tunnel 9, second-mode waves could be seen in power spectra computed from records as short as 80 micro-s. The second-mode wave amplitudes were observed to saturate and then begin to decrease in the Langley tunnels, indicating wave breakdown. Breakdown was estimated to occur near N approx. equals 5 in the Langley Mach-10 tunnel. The unit-Reynolds-number variations in the data from Tunnel 9 were too large to see the same processes. In Tunnel 9, the measured transition locations were found to be at N = 4.5 using thermocouples, and N = 5.3 using 50-kHz-response pressure sensors. What appears to be a very long transitional region was observed at a unit Reynolds number of 13.5 million per meter in Tunnel 9. These results were consistent with the high-frequency pressure fluctuation measurements. High-frequency pressure fluctuation measurements indicated that transition did occur in the Langley Mach-6 tunnel, but the location of transition was not precisely determined. Unit Reynolds numbers in the Langley Mach-10 tunnel were too low to observe transition. More analysis of this data set is expected in the future.

  13. Space shuttle orbiter rear mounted reaction control system jet interaction study. [hypersonic wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Rausch, J. R.

    1977-01-01

    The effect of interaction between the reaction control system (RCS) jets and the flow over the space shuttle orbiter in the atmosphere was investigated in the NASA Langley 31-inch continuous flow hypersonic tunnel at a nominal Mach number of 10.3 and in the AEDC continuous flow hypersonic tunnel B at a nominal Mach number of 6, using 0.01 and .0125 scale force models with aft RCS nozzles mounted both on the model and on the sting of the force model balance. The data show that RCS nozzle exit momentum ratio is the primary correlating parameter for effects where the plume impinges on an adjacent surface and mass flow ratio is the parameter when the plume interaction is primarily with the external stream. An analytic model of aft mounted RCS units was developed in which the total reaction control moments are the sum of thrust, impingement, interaction, and cross-coupling terms.

  14. The STD/MHD codes - Comparison of analyses with experiments at AEDC/HPDE, Reynolds Metal Co., and Hercules, Inc. [for MHD generator flows

    NASA Technical Reports Server (NTRS)

    Vetter, A. A.; Maxwell, C. D.; Swean, T. F., Jr.; Demetriades, S. T.; Oliver, D. A.; Bangerter, C. D.

    1981-01-01

    Data from sufficiently well-instrumented, short-duration experiments at AEDC/HPDE, Reynolds Metal Co., and Hercules, Inc., are compared to analyses with multidimensional and time-dependent simulations with the STD/MHD computer codes. These analyses reveal detailed features of major transient events, severe loss mechanisms, and anomalous MHD behavior. In particular, these analyses predicted higher-than-design voltage drops, Hall voltage overshoots, and asymmetric voltage drops before the experimental data were available. The predictions obtained with these analyses are in excellent agreement with the experimental data and the failure predictions are consistent with the experiments. The design of large, high-interaction or advanced MHD experiments will require application of sophisticated, detailed and comprehensive computational procedures in order to account for the critical mechanisms which led to the observed behavior in these experiments.

  15. 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

  16. Laser velocimeter optical traverse scheme: An investigation of a proposed optical scanning technique for Arnold Engineering and Development Center's four-foot transonic wind tunnel

    NASA Astrophysics Data System (ADS)

    Krajci, G. S.

    1983-12-01

    This investigation analyzed a nonstandard laser velocimeter setup proposed for use in AEDC Wind Tunnel 4T. The setup uses a gimballed mirror to move the probe volume from point to point, and the translation of a lens to control the distance in the tunnel the probe volume reaches. Results show that for equal indices of refraction inside and outside the tunnel, the laser beams of a converging pair do not totally converge with its associated beam except under certain conditions, and the probe volumes created by each pair of overlapping laser beams do not always coincide. This work then provides the conditions necessary for total convergence of a pair of laser beams for this setup. A solution is then proposed to insure convergence of each laser beam pair and overlap of the two probe volumes. More than a solution to the above problems, a method is given to determine the azimuth and elevation angles for a mirror such that the reflected beam off the mirror passes through a given point in the tunnel after traversing a window. To carry out these investigations, a computer code was written to simulate the nonstandard laser velocimeter setup, and a second code was written to determine the azimuth and elevation angles for a mirror such that the reflected beam off the mirror passes through a given point in the tunnel after traversing a window. Both codes were written in FORTRAN 77, implemented on a CDC 6000-CYBER 74.

  17. 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)

  18. Carpal Tunnel Syndrome

    MedlinePlus

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

  19. Overview of Experimental Investigations for Ares I Launch Vehicle Development

    NASA Technical Reports Server (NTRS)

    Tomek, William G.; Erickson, Gary E.; Pinier, Jeremy T.; Hanke, Jeremy L.

    2011-01-01

    Another concern for the vehicle during its design trajectory was the separation of the first stage solid rocket booster from the upper stage component after it had depleted its solid fuel propellant. There has been some concern about the interstage of the first stage from clearing the nozzle of the J2-X engine. A detailed separation aerodynamic wind tunnel investigation was conducted in the AEDC VKF Tunnel A to help to investigate the interaction aerodynamic effects5. A comparison of the separation plane details between the Ares I architecture and the Ares I-X demonstration flight architecture is shown in figure 12. The Ares I design requires a more complex separation sequence and requires better control in order to avoid contact with the nozzle of the upper stage engine. The interstage, which houses the J2-X engine for the Ares I vehicle, must be able to separate cleanly to avoid contact of the J2-X engine. There is only about approximately 18 inches of buffer inside the interstage on each size of the nozzle so this is a challenging controlled separation event. This complex experimental investigation required two separate Ares I models (upper stage and first stage with interstage attached) with independent strain gauge balances installed in each model. It also required the Captive Trajectory System (CTS) that was needed to precisely locate the components in space relative to each other to fill out the planned test matrix. The model setup in the AEDC VKF Tunnel A is shown in figure 13. The CTS remotely positioned the first stage at the required x, y, and z positions and was able to provide interactions within 0.2" of the upper stage. A sample of the axial force on the first stage booster is shown in figure 14. These results, as a function of separation distance between the two stages, are compared to pre-test CFD results. Since this is a very challenging, highly unsteady flow field for CFD to correctly model, the experimental results have been utilized by GN

  20. Ares I and Ares I-X Stage Separation Aerodynamic Testing

    NASA Technical Reports Server (NTRS)

    Pinier, Jeremy T.; Niskey, Charles J.

    2011-01-01

    The aerodynamics of the Ares I crew launch vehicle (CLV) and Ares I-X flight test vehicle (FTV) during stage separation was characterized by testing 1%-scale models at the Arnold Engineering Development Center s (AEDC) von Karman Gas Dynamics Facility (VKF) Tunnel A at Mach numbers of 4.5 and 5.5. To fill a large matrix of data points in an efficient manner, an injection system supported the upper stage and a captive trajectory system (CTS) was utilized as a support system for the first stage located downstream of the upper stage. In an overall extremely successful test, this complex experimental setup associated with advanced postprocessing of the wind tunnel data has enabled the construction of a multi-dimensional aerodynamic database for the analysis and simulation of the critical phase of stage separation at high supersonic Mach numbers. Additionally, an extensive set of data from repeated wind tunnel runs was gathered purposefully to ensure that the experimental uncertainty would be accurately quantified in this type of flow where few historical data is available for comparison on this type of vehicle and where Reynolds-averaged Navier-Stokes (RANS) computational simulations remain far from being a reliable source of static aerodynamic data.

  1. Tunneling nanotubes

    PubMed Central

    Austefjord, Magnus Wiger; Gerdes, Hans-Hermann; Wang, Xiang

    2014-01-01

    Tunneling nanotubes (TNTs) are recently discovered thin membranous tubes that interconnect cells. During the last decade, research has shown TNTs to be diverse in morphology and composition, varying between and within cell systems. In addition, the discovery of TNT-like extracellular protrusions, as well as observations of TNTs in vivo, has further enriched our knowledge on the diversity of TNT-like structures. Considering the complex molecular mechanisms underlying the formation of TNTs, as well as their different functions in intercellular communication, it is important to decipher how heterogeneity of TNTs is established, and to address what roles the compositional elements have in the execution of various functions. Here, we review the current knowledge on the morphological and structural diversity of TNTs, and address the relation between the formation, the structure, and the function of TNTs. PMID:24778759

  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. Variable-Density Tunnel

    NASA Technical Reports Server (NTRS)

    1921-01-01

    Wind Tunnel #2, building interior. Reinforced concrete foundation for Variable-Density Tunnel (VDT) under construction. The tank and contents weighed about 100 tons. Negative on roll #1 of copy negatives returned by National Archives on 70mm film rolls.

  4. Variable-Density Tunnel - Wind Tunnel #2

    NASA Technical Reports Server (NTRS)

    1923-01-01

    Underside of the Variable-Density Tunnel (VDT). The compressors are to the left. Balance detail - entrance view of wind tunnel #2. The photographer was probably shooting film for Dr. Joseph Ames' Wilbur Wright Memorial Lecture given to the Royal Aeronautical Society on May 31, 1923.

  5. The Tunnels of Samos

    NASA Technical Reports Server (NTRS)

    Apostol, Tom M. (Editor)

    1995-01-01

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

  6. 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.

  7. 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.

  8. 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.

  9. Inelastic tunnel diodes

    NASA Technical Reports Server (NTRS)

    Anderson, L. M. (Inventor)

    1984-01-01

    Power is extracted from plasmons, photons, or other guided electromagnetic waves at infrared to midultraviolet frequencies by inelastic tunneling in metal-insulator-semiconductor-metal diodes. Inelastic tunneling produces power by absorbing plasmons to pump electrons to higher potential. Specifically, an electron from a semiconductor layer absorbs a plasmon and simultaneously tunnels across an insulator into metal layer which is at higher potential. The diode voltage determines the fraction of energy extracted from the plasmons; any excess is lost to heat.

  10. Resonance enhanced tunneling

    NASA Astrophysics Data System (ADS)

    Matsumoto, S.; Yoshimura, M.

    2000-12-01

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

  11. 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.

  12. Atom Tunneling in Chemistry.

    PubMed

    Meisner, Jan; Kästner, Johannes

    2016-04-25

    Quantum mechanical tunneling of atoms is increasingly found to play an important role in many chemical transformations. Experimentally, atom tunneling can be indirectly detected by temperature-independent rate constants at low temperature or by enhanced kinetic isotope effects. In contrast, the influence of tunneling on the reaction rates can be monitored directly through computational investigations. The tunnel effect, for example, changes reaction paths and branching ratios, enables chemical reactions in an astrochemical environment that would be impossible by thermal transition, and influences biochemical processes. PMID:26990917

  13. 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.

  14. Micromachined Tunneling Accelerometer

    NASA Technical Reports Server (NTRS)

    Kenny, Thomas W.; Waltman, Stephen B.; Kaiser, William J.; Reynolds, Joseph K.

    1993-01-01

    Separation of tunneling electrodes adjusted by varying electrostatic force. Major components of tunneling transducer formed on two silicon chips by microfabrication techniques. Use of electrostatic deflection reduces sensitivity of transducer to thermal drift and simplifies design. Sensitivity suitable for applications in which larger acceleration-sensing instruments required.

  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. Variable-Density Tunnel - Wind Tunnel #2

    NASA Technical Reports Server (NTRS)

    1923-01-01

    Underside of the Variable-Density Tunnel (VDT). The compressors are to the left. Circular screened cone is shown. The photographer was probably shooting film for Dr. Joseph Ames' Wilbur Wright Memorial Lecture given to the Royal Aeronautical Society on May 31, 1923.

  17. Variable-Density Tunnel - Wind Tunnel #2

    NASA Technical Reports Server (NTRS)

    1922-01-01

    Equipment used for pressurizing the Variable-Density Tunnel (VDT): The VDT tunnel is on the right; the compressors are on the left. Figure 4 in the NACA Technical Report 227 (Part 2) identifies each piece of equipment visible in this diagram. Immediately visible in the lower left corner is the Booster Compressor. In the right rear (behind the tunnel) is Primary Compressor No. 1. (Primary Compressor No. 2 is not visible.) From NACA TR 227 (Part 2):'The air is compressed in two or three stages, according to the terminal pressure in the tank. A two-stage primary compressor is used up to a terminal pressure of about seven atmospheres. For pressures above this a booster compressor is used in conjunction with the primary compressor. The booster compressor may be used also as an exhauster when it is desired to operate the tunnel at pressures below that of the atmosphere. The primary compressors are driven by 250-horsepower synchronous motors and the booster compressor by a 150-horsepower squirrel-cage induction motor.' Jerome Hunsaker wrote in 'Forty Years of Aeronautical Research': 'In June 1921, the executive committee [of the NACA] decided to build a new kind of wind tunnel. Utilizing compressed air, it would allow for *scale effects in aerodynamic model experiments. This tunnel represented the first bold step by the NACA to provide its research personnel with the novel, often complicated, and usually expensive equipment necessary to press forward the frontiers of aeronautical science. It was designed by Dr. Max Munk, formerly of G*ttingen.' Eastman Jacobs wrote in an article in a 1927 article for Aviation that: 'The tunnel is inclosed (sic) within a steel shell, so that the density of the air inside may be increased by pumping air into the shell to a pressure of 300 lb. per sq. in. A 250 hp. motor, driving a propeller, circulates the air, drawing it through the five-foot test section at a velocity of about fifty miles per hour. The model is mounted in the throat of

  18. 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.

  19. Carpal Tunnel Syndrome

    MedlinePlus

    ... through NIH's National Center for Complementary and Alternative Medicine are investigating the effects of acupuncture on pain, loss of median nerve function, and changes in the brain associated with carpal tunnel syndrome. In addition, a ...

  20. TOPICAL REVIEW: Recognition tunneling

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    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.

  1. Channel-tunnels.

    PubMed

    Koronakis, V; Andersen, C; Hughes, C

    2001-08-01

    TolC and its many homologues comprise an alpha-helical transperiplasmic tunnel embedded in the bacterial outer membrane by a contiguous beta-barrel channel, providing a large exit duct for diverse substrates. The 'channel-tunnel' is closed at its periplasmic entrance, but can be opened by an 'iris-like' mechanism when recruited by substrate-engaged proteins in the cytosolic membrane.

  2. 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.

  3. 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.

  4. 203. Lickstone Ridge Tunnel. All but three of the tunnel ...

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

    203. Lickstone Ridge Tunnel. All but three of the tunnel have minimum height of 13, which accommodates most large recreational vehicles. This tunnel has the lowest clearance at 11-3. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  5. 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

  6. 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.

  7. Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Reiss, Günter; Schmalhorst, Jan; Thomas, Andre; Hütten, Andreas; Yuasa, Shinji

    In magnetoelectronic devices large opportunities are opened by the spin dependent tunneling resistance, where a strong dependence of the tunneling current on the relative orientation of the magnetization of the electrodes is found. Within a short time, the amplitude of the resistance change of the junctions increased dramatically. We will cover Al-O and MgO based junctions and present highly spin-polarized electrode materials such as Heusler alloys. Furthermore, we will give a short overview on applications such as read heads in hard disk drives, storage cells in MRAMs, field programmable logic circuits and biochips. Finally, we will discuss the currently growing field of current induced magnetization switching.

  8. 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.

  9. Eliminating Wind Tunnel Flow Breakdown

    NASA Technical Reports Server (NTRS)

    Hackett, J. E.

    1983-01-01

    Undesirable vortexes near floor in small wind tunnels suppressed by simple device that alters flow pattern there. Air is injected along floor and interacts with backflow from wind-tunnel model. Results in smoother, more correct air-flow and to more-reliable wind-tunnel data.

  10. 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.

  11. Quiet wind tunnel

    NASA Technical Reports Server (NTRS)

    Howard, P. W.; Schutzenhofer, L. A.

    1978-01-01

    Simple and inexpensive technique suppresses background noise generated by pores in wind tunnel wall lining and makes aerodynamic data more accurate and reliable. Porous walls are covered with wire-mesh screen. Screen offers smoother surface to airflow and damps vortexes and resonance caused by wall perforations; yet it provides enough open area for perforations to cancel shock waves generated by model.

  12. Propeller Research Tunnel

    NASA Technical Reports Server (NTRS)

    1926-01-01

    This picture shows a general view of the Propeller Research Tunnel engine room under construction. Workmen were installing the two submarine diesel engines that would power the PRT. The room was constructed of concrete with corrugated metal siding and roofing with the intention of making the engine room as fireproof as possible.

  13. Prions tunnel between cells.

    PubMed

    Gerdes, Hans-Hermann

    2009-03-01

    Prions are abnormal isoforms of host proteins that are the infectious agents in certain mammalian neurodegenerative diseases. How prions travel from their peripheral entry sites to the brain where they cause disease is poorly understood. A new study finds that tunnelling nanotubes are important for the intercellular transfer of prions during neuroinvasion.

  14. 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.

  15. Carpal Tunnel Syndrome

    PubMed Central

    Mahoney, James Leo; Dagum, Alexander B.

    1992-01-01

    Carpal tunnel syndrome is a very common hand problem usually presenting with nighttime pain, numbness, and loss of dexterity. Controversy arises over the diagnosis, treatment, and evaluation of results. Nighttime splinting will improve the symptoms in some patients. If this fails, excellent results can be achieved with surgical decompression of the median nerve in the carpal canal. PMID:21221355

  16. 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.

  17. 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.

  18. 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

  19. Introduction to cryogenic wind tunnels

    NASA Technical Reports Server (NTRS)

    Goodyer, M. J.

    1985-01-01

    The background to the evolution of the cryogenic wind tunnel is outlined, with particular reference to the late 60's/early 70's when efforts were begun to re-equip with larger wind tunnels. The problems of providing full scale Reynolds numbers in transonic testing were proving particularly intractible, when the notion of satisfying the needs with the cryogenic tunnel was proposed, and then adopted. The principles and advantages of the cryogenic tunnel are outlined, along with guidance on the coolant needs when this is liquid nitrogen, and with a note on energy recovery. Operational features of the tunnels are introduced with reference to a small low speed tunnel. Finally the outstanding contributions are highlighted of the 0.3-Meter Transonic Cryogenic Tunnel (TCT) at NASA Langley Research Center, and its personnel, to the furtherance of knowledge and confidence in the concept.

  20. Techniques For Mass Production Of Tunneling Electrodes

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    Techniques for mass production of tunneling electrodes developed from silicon-micromachining, lithographic patterning, and related microfabrication processes. Tunneling electrodes named because electrons travel between them by quantum-mechanical tunneling; tunneling electrodes integral parts of tunneling transducer/sensors, which act in conjunction with feedback circuitry to stabilize tunneling currents by maintaining electrode separations of order of 10 Angstrom. Essential parts of scanning tunneling microscopes and related instruments, and used as force and position transducers in novel microscopic accelerometers and infrared detectors.

  1. 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.

  2. 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.

  3. 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.

  4. On tunneling across horizons

    NASA Astrophysics Data System (ADS)

    Vanzo, L.

    2011-07-01

    The tunneling method for stationary black holes in the Hamilton-Jacobi variant is reconsidered in the light of some critiques that have been moved against. It is shown that once the tunneling trajectories have been correctly identified the method is free from internal inconsistencies, it is manifestly covariant, it allows for the extension to spinning particles and it can even be used without solving the Hamilton-Jacobi equation. These conclusions borrow support on a simple analytic continuation of the classical action of a pointlike particle, made possible by the unique assumption that it should be analytic in the complexified Schwarzschild or Kerr-Newman space-time. A more general version of the Parikh-Wilczek method will also be proposed along these lines.

  5. Unitary Plan Supersonic Tunnel

    NASA Technical Reports Server (NTRS)

    1953-01-01

    Unitary Plan Supersonic Tunnel: In this aerial photograph of construction in the early 1950s, the return air passages are shown in the rear, center. This area was later covered with walls and a roof so that upon completion of the facility, it was not visible from the exterior. Three air storage spheres and the cooling tower are at the extreme right of the building. The spheres store dry air at 150 pounds per square inch. The cooling tower dissipates heat from coolers that control the test air temperature. One of many research facilities at NASA Langley Research Center in Hampton, Virginia, the Unitary Plan Wind Tunnel is used for experimental investigations at supersonic speeds.

  6. Light tunneling in clouds.

    PubMed

    Nussenzveig, H Moyses

    2003-03-20

    Solar radiation, traveling outside cloud water droplets, excites sharp resonances and surface waves by tunneling into the droplets. This effect contributes substantially to the total absorption (typically, of the order of 20%) and yields the major contribution to backscattering, producing the meteorological glory. Usual computational practices in atmospheric science misrepresent resonance contributions and cannot be relied on in the assessment of possible anomalies in cloud absorption.

  7. Anterior cruciate ligament tunnel placement.

    PubMed

    Wolf, Brian R; Ramme, Austin J; Britton, Carla L; Amendola, Annunziato

    2014-08-01

    The purpose of this cadaveric study was to analyze variation in anterior cruciate ligament (ACL) tunnel placement between surgeons and the influence of preferred surgical technique and surgeon experience level using three-dimensional (3D) computed tomography (CT). In this study, 12 surgeons drilled ACL tunnels on six cadaveric knees each. Surgeons were divided by experience level and preferred surgical technique (two-incision [TI], medial portal [MP], and transtibial [TT]). ACL tunnel aperture locations were analyzed using 3D CT scans and compared with radiographic ACL footprint criteria. The femoral tunnel location from front to back within the notch demonstrated a range of means of 16% with the TI tunnels the furthest back. A range of means of only 5% was found for femoral tunnel low to high positions by technique. The anterior to posterior tibial tunnel measure demonstrated wider variation than the medial to lateral position. The mean tibial tunnel location drilled by TT surgeons was more posterior than surgeons using the other techniques. Overall, 82% of femoral tunnels and 78% of tibial tunnels met all radiographic measurement criteria. Slight (1-7%) differences in mean tunnel placement on the femur and tibia were found between experienced and new surgeons. The location of the femoral tunnel aperture in the front to back plane relative to the notch roof and the anterior to posterior position on the tibia were the most variable measures. Surgeon experience level did not appear to significantly affect tunnel location. This study provides background information that may be beneficial when evaluating multisurgeon and multicenter collaborative ACL studies.

  8. 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.

  9. Ferroelectric tunnel memristor.

    PubMed

    Kim, D J; Lu, H; Ryu, S; Bark, C-W; Eom, C-B; Tsymbal, E Y; Gruverman, A

    2012-11-14

    Strong interest in resistive switching phenomena is driven by a possibility to develop electronic devices with novel functional properties not available in conventional systems. Bistable resistive devices are characterized by two resistance states that can be switched by an external voltage. Recently, memristors-electric circuit elements with continuously tunable resistive behavior-have emerged as a new paradigm for nonvolatile memories and adaptive electronic circuit elements. Employment of memristors can radically enhance the computational power and energy efficiency of electronic systems. Most of the existing memristor prototypes involve transition metal oxide resistive layers where conductive filaments formation and/or the interface contact resistance control the memristive behavior. In this paper, we demonstrate a new type of memristor that is based on a ferroelectric tunnel junction, where the tunneling conductance can be tuned in an analogous manner by several orders of magnitude by both the amplitude and the duration of the applied voltage. The ferroelectric tunnel memristors exhibit a reversible hysteretic nonvolatile resistive switching with a resistance ratio of up to 10(5) % at room temperature. The observed memristive behavior is attributed to the field-induced charge redistribution at the ferroelectric/electrode interface, resulting in the modulation of the interface barrier height. PMID:23039785

  10. Ferroelectric tunnel memristor.

    PubMed

    Kim, D J; Lu, H; Ryu, S; Bark, C-W; Eom, C-B; Tsymbal, E Y; Gruverman, A

    2012-11-14

    Strong interest in resistive switching phenomena is driven by a possibility to develop electronic devices with novel functional properties not available in conventional systems. Bistable resistive devices are characterized by two resistance states that can be switched by an external voltage. Recently, memristors-electric circuit elements with continuously tunable resistive behavior-have emerged as a new paradigm for nonvolatile memories and adaptive electronic circuit elements. Employment of memristors can radically enhance the computational power and energy efficiency of electronic systems. Most of the existing memristor prototypes involve transition metal oxide resistive layers where conductive filaments formation and/or the interface contact resistance control the memristive behavior. In this paper, we demonstrate a new type of memristor that is based on a ferroelectric tunnel junction, where the tunneling conductance can be tuned in an analogous manner by several orders of magnitude by both the amplitude and the duration of the applied voltage. The ferroelectric tunnel memristors exhibit a reversible hysteretic nonvolatile resistive switching with a resistance ratio of up to 10(5) % at room temperature. The observed memristive behavior is attributed to the field-induced charge redistribution at the ferroelectric/electrode interface, resulting in the modulation of the interface barrier height.

  11. Analysis of shield tunnel

    NASA Astrophysics Data System (ADS)

    Ding, W. Q.; Yue, Z. Q.; Tham, L. G.; Zhu, H. H.; Lee, C. F.; Hashimoto, T.

    2004-01-01

    This paper proposes a two-dimensional finite element model for the analysis of shield tunnels by taking into account the construction process which is divided into four stages. The soil is assumed to behave as an elasto-plastic medium whereas the shield is simulated by beam-joint discontinuous model in which curved beam elements and joint elements are used to model the segments and joints, respectively. As grout is usually injected to fill the gap between the lining and the soil, the property parameters of the grout are chosen in such a way that they can reflect the state of the grout at each stage. Furthermore, the contact condition between the soil and lining will change with the construction stage, and therefore, different stress-releasing coefficients are used to account for the changes. To assess the accuracy that can be attained by the method in solving practical problems, the shield tunnelling in the No. 7 Subway Line Project in Osaka, Japan, is used as a case history for our study. The numerical results are compared with those measured in the field. The results presented in the paper show that the proposed numerical procedure can be used to effectively estimate the deformation, stresses and moments experienced by the surrounding soils and the concrete lining segments. The analysis and method presented in this paper can be considered to be useful for other subway construction projects involving shield tunnelling in soft soils. Copyright

  12. 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.

  13. Tunnelling from black holes and tunnelling into white holes

    NASA Astrophysics Data System (ADS)

    Chatterjee, Bhramar; Ghosh, A.; Mitra, P.

    2008-03-01

    Hawking radiation is nowadays being understood as tunnelling through black hole horizons. Here, the extension of the Hamilton-Jacobi approach to tunnelling for non-rotating and rotating black holes in different non-singular coordinate systems not only confirms this quantum emission from black holes but also reveals the new phenomenon of absorption into white holes by quantum mechanical tunnelling. The rôle of a boundary condition of total absorption or emission is also clarified.

  14. Submucosal tunneling techniques: current perspectives

    PubMed Central

    Kobara, Hideki; Mori, Hirohito; Rafiq, Kazi; Fujihara, Shintaro; Nishiyama, Noriko; Ayaki, Maki; Yachida, Tatsuo; Matsunaga, Tae; Tani, Johji; Miyoshi, Hisaaki; Yoneyama, Hirohito; Morishita, Asahiro; Oryu, Makoto; Iwama, Hisakazu; Masaki, Tsutomu

    2014-01-01

    Advances in endoscopic submucosal dissection include a submucosal tunneling technique, involving the introduction of tunnels into the submucosa. These tunnels permit safer offset entry into the peritoneal cavity for natural orifice transluminal endoscopic surgery. Technical advantages include the visual identification of the layers of the gut, blood vessels, and subepithelial tumors. The creation of a mucosal flap that minimizes air and fluid leakage into the extraluminal cavity can enhance the safety and efficacy of surgery. This submucosal tunneling technique was adapted for esophageal myotomy, culminating in its application to patients with achalasia. This method, known as per oral endoscopic myotomy, has opened up the new discipline of submucosal endoscopic surgery. Other clinical applications of the submucosal tunneling technique include its use in the removal of gastrointestinal subepithelial tumors and endomicroscopy for the diagnosis of functional and motility disorders. This review suggests that the submucosal tunneling technique, involving a mucosal safety flap, can have potential values for future endoscopic developments. PMID:24741323

  15. Orbiter Model in Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Marshall Space Flight Center (MSFC) engineer holding a replica of the proposed Liquid Booster Module, observes the testing of a small Space Shuttle orbiter model at 14 Wind Tunnel at MSFC. 14 Wind Tunnel is a trisonic wind tunnel, which is capable of running subsonic, transonic, and supersonic. It is used to test the integrity of rockets and launch vehicles in launch and reentry environments. The Wind Tunnel was used to test rockets and launch vehicles from the Jupiter C through the Saturn family up to the current Space Shuttle and will be used to test future advanced launch vehicles.

  16. View of Water Storage Tank off entrance tunnel. Tunnel at ...

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

    View of Water Storage Tank off entrance tunnel. Tunnel at left of image to Launch Silos - Titan One Missile Complex 2A, .3 miles west of 129 Road and 1.5 miles north of County Line Road, Aurora, Adams County, CO

  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. Retrofitting tunnel kilns

    SciTech Connect

    Lukacs, J.J.

    1997-02-01

    Significant benefits can be achieved by retrofitting tunnel kilns. The decision-making process to do so starts with evaluating short- and long-term goals. Plant goals can influence tradeoffs in burner sizing, burner choice and control scheme. The evaluation includes consideration of increased production, reduced breakage during heating and cooling, improved quality, ability to quickly change products, reduced fuel use, reduced energy consumption and/or improved control. The efforts in one area affect performance in other areas. For example, reduced fuel use implies reduced energy consumption. Regardless of the priority of the goals, the first step is an evaluation of the existing burners.

  20. Virtual-detector approach to tunnel ionization and tunneling times

    NASA Astrophysics Data System (ADS)

    Teeny, Nicolas; Keitel, Christoph H.; Bauke, Heiko

    2016-08-01

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

  1. 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)

  2. 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

  3. 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.

  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. Tunnel electroresistance through organic ferroelectrics

    PubMed Central

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

    2016-01-01

    Organic electronics is emerging for large-area applications such as photovoltaic cells, rollable displays or electronic paper. Its future development and integration will require a simple, low-power organic memory, that can be written, erased and readout electrically. Here we demonstrate a non-volatile memory in which the ferroelectric polarisation state of an organic tunnel barrier encodes the stored information and sets the readout tunnel current. We use high-sensitivity piezoresponse force microscopy to show that films as thin as one or two layers of ferroelectric poly(vinylidene fluoride) remain switchable with low voltages. Submicron junctions based on these films display tunnel electroresistance reaching 1,000% at room temperature that is driven by ferroelectric switching and explained by electrostatic effects in a direct tunnelling regime. Our findings provide a path to develop low-cost, large-scale arrays of organic ferroelectric tunnel junctions on silicon or flexible substrates. PMID:27143121

  7. 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.

  8. Carpal tunnel syndrome and acromegaly.

    PubMed

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

    1986-01-01

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

  9. Tunnel electroresistance through organic ferroelectrics

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  10. Tunnel electroresistance through organic ferroelectrics.

    PubMed

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

    2016-01-01

    Organic electronics is emerging for large-area applications such as photovoltaic cells, rollable displays or electronic paper. Its future development and integration will require a simple, low-power organic memory, that can be written, erased and readout electrically. Here we demonstrate a non-volatile memory in which the ferroelectric polarisation state of an organic tunnel barrier encodes the stored information and sets the readout tunnel current. We use high-sensitivity piezoresponse force microscopy to show that films as thin as one or two layers of ferroelectric poly(vinylidene fluoride) remain switchable with low voltages. Submicron junctions based on these films display tunnel electroresistance reaching 1,000% at room temperature that is driven by ferroelectric switching and explained by electrostatic effects in a direct tunnelling regime. Our findings provide a path to develop low-cost, large-scale arrays of organic ferroelectric tunnel junctions on silicon or flexible substrates. PMID:27143121

  11. Electromagnetics for Detecting Shallow Tunnels

    NASA Astrophysics Data System (ADS)

    Won, I.

    2006-05-01

    Detecting tunnels by geophysical means, even very shallow ones, has been difficult, to say the least. Despite heavy R&D funding from the military since the early 70s, geophysicists have not produced tools that are simple and practical enough to meet the military needs. The initial interest and R&D funding on the subject perhaps started with the Vietcong tunnels in the 60s. Tunnels in the Korean DMZ, first found in the mid 70s, sharply escalated the R&D spending. During the 90s, covert tunnels along the US-Mexico border have kept the topic alive but at a minimal funding level. Most recent interest appears to be in the terrorism-related shallow tunnels, more or less anywhere in the regions of conflict. Despite the longstanding effort in the geophysical community under heavy public funding, there is a dearth of success stories where geophysicists can actually claim to have found hitherto unknown tunnels. For instance, geophysics has not discovered a single tunnel in Vietnam or in Korea! All tunnels across the Korean DMZ were found from human intelligence. The same is true to all illicit tunnels found along the southwestern border. The tunnels under discussion are clandestine, which implies that the people who built them do not wish others to succeed in finding them. The place around the tunnel, therefore, may not be the friendliest venue for surveyors to linger around. The situation requires tools that are fast, little noticeable, and hardly intrusive. Many geophysical sensors that require ground contacts, such as geophones and electrodes that are connected by a myriad of cables, may not be ideal in this situation. On the other hand, a sensor that can be carried by vehicle without stopping, and is nothing obviously noticeable to bystanders, could be much more acceptable. Working at unfriendly environment also requires forgoing our usual practices where we collect data leisurely and make pretty maps later. To be useful, geophysical tools must be able to process

  12. Tunneling electroresistance effect in ferroelectric tunnel junctions at the nanoscale.

    PubMed

    Gruverman, A; Wu, D; Lu, H; Wang, Y; Jang, H W; Folkman, C M; Zhuravlev, M Ye; Felker, D; Rzchowski, M; Eom, C-B; Tsymbal, E Y

    2009-10-01

    Using a set of scanning probe microscopy techniques, we demonstrate the reproducible tunneling electroresistance effect on nanometer-thick epitaxial BaTiO(3) single-crystalline thin films on SrRuO(3) bottom electrodes. Correlation between ferroelectric and electronic transport properties is established by direct nanoscale visualization and control of polarization and tunneling current. The obtained results show a change in resistance by about 2 orders of magnitude upon polarization reversal on a lateral scale of 20 nm at room temperature. These results are promising for employing ferroelectric tunnel junctions in nonvolatile memory and logic devices. PMID:19697939

  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. Variable-Density Tunnel

    NASA Technical Reports Server (NTRS)

    1921-01-01

    The outside pressure shell for the Variable-Density Tunnel (VDT). The shell, or 'tank' as it was called, was built in the Newport News Shipyard and traveled by barge to Langley. The tank could withstand a working pressure of 21 atmospheres. Elton Miller described it in NACA TR No. 227 (pp. 411-412): 'It is built of steel plates lapped and riveted according to the usual practice in steam boiler construction, although, because of the size of the tank and the high working pressure, the construction is unusually heavy. There is a cylindrical body portion of 2-1/8 inch (53.98 millimeters) steel plate with hemispherical ends 1-1/4 inches (31.75 millimeters) in thickness.'

  15. 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.

  16. Spin tunneling in conducting oxides

    SciTech Connect

    Bratkovsky, A.

    1998-12-31

    Different tunneling mechanisms in conventional and half-metallic ferromagnetic tunnel junctions are analyzed within the same general method. Direct tunneling is compared with impurity-assisted, surface state assisted, and inelastic contributions to a tunneling magnetoresistance (TMR). Theoretically calculated direct tunneling in iron group systems leads to about a 30% change in resistance, which is close to experimentally observed values. It is shown that the larger observed values of the TMR might be a result of tunneling involving surface polarized states. The authors find that tunneling via resonant defect states in the barrier radically decreases the TMR (down to 4% with Fe-based electrodes), and a resonant tunnel diode structure would give a TMR of about 8%. With regards to inelastic tunneling, magnons and phonons exhibit opposite effects: one-magnon emission generally results in spin mixing and, consequently, reduces the TMR, whereas phonons are shown to enhance the TMR. The inclusion of both magnons and phonons reasonably explains an unusually bias dependence of the TMR. The model presented here is applied qualitatively to half-metallics with 100% spin polarization, where one-magnon processes are suppressed and the change in resistance in the absence of spin-mixing on impurities may be arbitrarily large. Even in the case of imperfect magnetic configurations, the resistance change can be a few 1,000%. Examples of half-metallic systems are CrO{sub 2}/TiO{sub 2} and CrO{sub 2}/RuO{sub 2}, and an account of their peculiar band structures is presented. The implications and relation of these systems to CMR materials, which are nearly half-metallic, are discussed.

  17. Dual-Element Tunneling Accelerometer

    NASA Technical Reports Server (NTRS)

    Kaiser, William J.; Kenny, Thomas W.; Rockstad, Howard K.; Reynolds, Joseph K.

    1994-01-01

    Improved micromachined tunneling accelerometer contains two deflecting transducer elements: One an elastically supported proof mass having relatively low resonant frequency; other cantilever tunneling transducer that tracks displacement of proof mass and has relatively high resonant frequency ({sup a} 10 kHz). Deflection voltage generated by circuit like described in "Wideband Feedback Circuit for Tunneling Sensor" (NPO-18866). Accelerometers of this type suited for underwater acoustic measurements, detecting vibrations associated with malfunctions in vehicles, detecting seismic signals, monitoring and controlling vibrations in structures, and other applications.

  18. Langley Spin Tunnel - Free Flight Tunnel - and models

    NASA Technical Reports Server (NTRS)

    1939-01-01

    Model shop for NACA Spin Tunnel and Free Flight Tunnel. Dynamically and geometrically accurate models with movable control surfaces are made here by men whose training as toy model makers is producing valuable results. The models are used for study of the stability and control of aircraft which is an essential basis for safety. Photograph published in Winds of Change, a 75th Anniversary NASA publication (page 10), by James Schultz.

  19. Tunneling progress on the Yucca Mountain Project

    SciTech Connect

    Hansmire, W.H.; Munzer, R.J.

    1996-06-01

    The current status of tunneling progress on the Yucca Mountain Project (YMP) is presented in this paper. The Exploratory Studies Facility (ESF), a key part of the YMP, has been long in development and construction is ongoing. This is a progress report on the tunneling aspects of the ESF as of January 1, 1996. For purposes of discussion in this summary, the tunneling has progressed in four general phases. The paper describes: tunneling in jointed rock under low stress; tunneling through the Bow Ridge Fault and soft rock; tunneling through the Imbricate Fault Zone; and Tunneling into the candidate repository formation.

  20. 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.

  1. 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.

  2. Icing Research Tunnel Test Section

    NASA Technical Reports Server (NTRS)

    1968-01-01

    Icing Research Tunnel Test Section NASA technician measuring ice deposits on an airfoil after completing a test at the Lewis Research Center. NASA Lewis is now known as John H. Glean Research Center at Lewis Field.

  3. 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.

  4. 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

  5. Quantum tunneling in flux compactifications

    NASA Astrophysics Data System (ADS)

    Blanco-Pillado, Jose J.; Schwartz-Perlov, Delia; Vilenkin, Alexander

    2009-12-01

    We identify instantons representing vacuum decay in a 6-dimensional toy model for string theory flux compactifications, with the two extra dimensions compactified on a sphere. We evaluate the instanton action for tunneling between different flux vacua, as well as for the decompactification decay channel. The bubbles resulting from flux tunneling have an unusual structure. They are bounded by two-dimensional branes, which are localized in the extra dimensions. This has important implications for bubble collisions.

  6. CARPAL TUNNEL SYNDROME AND WORK

    PubMed Central

    Newington, Lisa; Harris, E Clare; Walker-Bone, Karen

    2016-01-01

    INTRODUCTION AND SCOPE Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome and frequently presents in working-aged adults. Its mild form causes ‘nuisance’ symptoms including dysaesthesia and nocturnal waking. At its most severe however it can significantly impair motor function and weaken pinch grip. This review will discuss the anatomy of the carpal tunnel and the clinical presentation of the syndrome as well as the classification and diagnosis of the condition. Carpal tunnel syndrome has a profile of well-established risk factors including individual factors and predisposing co-morbidities, which will be briefly discussed. However, there is a growing body of evidence for an association between carpal tunnel syndrome and various occupational factors, which will also be discussed. Management of carpal tunnel syndrome, conservative and surgical will be described. Finally, we will discuss the issue of safe return to work post carpal tunnel release surgery and the lack of evidence-based guidelines. PMID:26612240

  7. Tunneling in strongly correlated materials

    NASA Astrophysics Data System (ADS)

    Maltseva, Marianna

    Tunneling studies of strongly correlated materials provide information about the nature of electronic correlations, which is vital for investigation of emergent materials at the microscopic level. In particular, scanning tunneling spectroscopy/microscopy (STS/STM) studies have made major contributions to understanding cuprate superconductors (66), yet there is a sense that huge STM data arrays contain much more precious information to be extracted and analyzed. One of the most pressing questions in the field is how to improve the data analysis, so as to extract more information from STM data. A dominant trend in STM data analysis has been to interpret the data within a particular microscopic model, while using only basic data analysis tools. To decrease the reliance of the STM data interpretation on particular microscopic models, further advances in data analysis methods are necessary. In Chapter 2 of this Thesis, we discuss how one can extract information about the phase of the order parameter from STM data. We show that symmetrized and anti-symmetrized correlators of local density of states give rise to observable coherence factor effects. In Chapter 3, we apply this framework to analyze the recent scanning tunneling experiments on an underdoped cuprate superconductor Ca2-xNaxCuO2Cl2 by T. Hanaguri et al. (60). In Chapter 4, we propose a model for nodal quasiparticle scattering in a disordered vortex lattice. Recently, scanning tunneling studies of a Kondo lattice material URu2Si2 became possible (117). If it proves possible to apply scanning tunneling spectroscopy to Kondo lattice materials, then remarkable new opportunities in the ongoing investigation may emerge. In Chapter 5, we examine the effect of co-tunneling to develop a theory of tunneling into a Kondo lattice. We find that the interference between the direct tunneling and the co-tunneling channels leads to a novel asymmetric lineshape, which has two peaks and a gap. The presence of the peaks suggests

  8. Improved multidimensional semiclassical tunneling theory.

    PubMed

    Wagner, Albert F

    2013-12-12

    We show that the analytic multidimensional semiclassical tunneling formula of Miller et al. [Miller, W. H.; Hernandez, R.; Handy, N. C.; Jayatilaka, D.; Willets, A. Chem. Phys. Lett. 1990, 172, 62] is qualitatively incorrect for deep tunneling at energies well below the top of the barrier. The origin of this deficiency is that the formula uses an effective barrier weakly related to the true energetics but correctly adjusted to reproduce the harmonic description and anharmonic corrections of the reaction path at the saddle point as determined by second order vibrational perturbation theory. We present an analytic improved semiclassical formula that correctly includes energetic information and allows a qualitatively correct representation of deep tunneling. This is done by constructing a three segment composite Eckart potential that is continuous everywhere in both value and derivative. This composite potential has an analytic barrier penetration integral from which the semiclassical action can be derived and then used to define the semiclassical tunneling probability. The middle segment of the composite potential by itself is superior to the original formula of Miller et al. because it incorporates the asymmetry of the reaction barrier produced by the known reaction exoergicity. Comparison of the semiclassical and exact quantum tunneling probability for the pure Eckart potential suggests a simple threshold multiplicative factor to the improved formula to account for quantum effects very near threshold not represented by semiclassical theory. The deep tunneling limitations of the original formula are echoed in semiclassical high-energy descriptions of bound vibrational states perpendicular to the reaction path at the saddle point. However, typically ab initio energetic information is not available to correct it. The Supporting Information contains a Fortran code, test input, and test output that implements the improved semiclassical tunneling formula. PMID:24224758

  9. Conversion of Non-Tunneled to Tunneled Hemodialysis Catheters

    SciTech Connect

    Ha, Thuong G. Van Fimmen, Derek; Han, Laura; Funaki, Brian S.; Santeler, Scott; Lorenz, Jonathan

    2007-04-15

    Purpose. To determine the safety and efficacy of conversion of non-tunneled (temporary) catheters to tunneled catheters in hemodialysis patients. Methods. A retrospective review of 112 consecutive conversions in 111 patients was performed over a period of 4 years. Fourteen patients were lost to follow-up. The remaining 97 patients had clinical follow-up. Temporary catheters were converted to tunneled catheters utilizing the same internal jugular venotomy sites and a modified over-the-wire technique with use of a peel-away sheath . Follow-up clinical data were reviewed. Results. Technical success was achieved in all 112 procedures. None of the 97 patients with follow-up suffered early infection within 30 days. The total number of follow-up catheter days was 13,659 (range 2-790). Cases of confirmed and suspected bacteremia requiring catheter removal occurred at a frequency of 0.10 per 100 catheter days. Suspected catheter infection treated with antibiotics but not requiring catheter intervention occurred at a frequency of 0.04 per 100 catheter days. Frequency of all suspected or confirmed infections was 0.14 per 100 catheter days. Catheter interventions as a result of poor blood flow, inadvertent removal, catheter fracture, or kinking occurred at a rate of 0.18 per 100 catheter days. Life table analysis revealed primary patency rates of 86%, 64%, and 39% at 30 days, 90 days, and 180 days, respectively. Conclusion. Conversion of temporary catheters to tunneled catheters using the pre-existing venotomy sites is safe and has low rates of infection and malfunction. These rates are comparable to previously published rates for tunneled catheters placed de novo and tunneled catheter exchanges.

  10. 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.

  11. 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).

  12. 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).

  13. Carpal tunnel syndrome and work.

    PubMed

    Newington, Lisa; Harris, E Clare; Walker-Bone, Karen

    2015-06-01

    Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome, and it frequently presents in working-aged adults. Its mild form causes 'nuisance' symptoms including dysaesthesia and nocturnal waking. At its most severe, CTS can significantly impair motor function and weaken pinch grip. This review discusses the anatomy of the carpal tunnel and the clinical presentation of the syndrome as well as the classification and diagnosis of the condition. CTS has a profile of well-established risk factors including individual factors and predisposing co-morbidities, which are briefly discussed. There is a growing body of evidence for an association between CTS and various occupational factors, which is also explored. Management of CTS, conservative and surgical, is described. Finally, the issue of safe return to work post carpal tunnel release surgery and the lack of evidence-based guidelines are discussed.

  14. Tunnelling in van der Waals heterostructures

    NASA Astrophysics Data System (ADS)

    Mishchenko, Artem; Novoselov, Kostya; Geim, Andre; Eaves, Laurence; Falko, Vladimir

    When graphene and other conductive two-dimensional (2D) materials are separated by an atomically thin insulating 2D crystal, quantum mechanical tunnelling leads to appreciable current between two 2D conductors due to the overlap of their wavefunctions. These tunnel devices demonstrate interesting physics and potential for applications: such effects as resonant tunnelling, negative differential conductance, light emission and detection have already been demonstrated. In this presentation we will outline the current status and perspectives of tunnelling transistors based on 2D materials assembled into van der Waals heterostructures. Particularly, we will present results on mono- and bilayer graphene tunnelling, tunnelling in 2D crystal-based quantum wells, and tunnelling in superconducting 2D materials. Such effects as momentum and chirality conservation, phonon- and impurity-assisted tunnelling will also be discussed. Finally, we will ponder the implications of discovered effects for practical applications.

  15. Computational multiqubit tunnelling in programmable quantum annealers.

    PubMed

    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

    2016-01-07

    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.

  16. 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

  17. Computational multiqubit tunnelling in programmable quantum annealers

    NASA Astrophysics Data System (ADS)

    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.

  18. Molecular series-tunneling junctions.

    PubMed

    Liao, Kung-Ching; Hsu, Liang-Yan; Bowers, Carleen M; Rabitz, Herschel; Whitesides, George M

    2015-05-13

    Charge transport through junctions consisting of insulating molecular units is a quantum phenomenon that cannot be described adequately by classical circuit laws. This paper explores tunneling current densities in self-assembled monolayer (SAM)-based junctions with the structure Ag(TS)/O2C-R1-R2-H//Ga2O3/EGaIn, where Ag(TS) is template-stripped silver and EGaIn is the eutectic alloy of gallium and indium; R1 and R2 refer to two classes of insulating molecular units-(CH2)n and (C6H4)m-that are connected in series and have different tunneling decay constants in the Simmons equation. These junctions can be analyzed as a form of series-tunneling junctions based on the observation that permuting the order of R1 and R2 in the junction does not alter the overall rate of charge transport. By using the Ag/O2C interface, this system decouples the highest occupied molecular orbital (HOMO, which is localized on the carboxylate group) from strong interactions with the R1 and R2 units. The differences in rates of tunneling are thus determined by the electronic structure of the groups R1 and R2; these differences are not influenced by the order of R1 and R2 in the SAM. In an electrical potential model that rationalizes this observation, R1 and R2 contribute independently to the height of the barrier. This model explicitly assumes that contributions to rates of tunneling from the Ag(TS)/O2C and H//Ga2O3 interfaces are constant across the series examined. The current density of these series-tunneling junctions can be described by J(V) = J0(V) exp(-β1d1 - β2d2), where J(V) is the current density (A/cm(2)) at applied voltage V and βi and di are the parameters describing the attenuation of the tunneling current through a rectangular tunneling barrier, with width d and a height related to the attenuation factor β. PMID:25871745

  19. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures shall...

  20. 49 CFR 177.810 - Vehicular tunnels.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Vehicular tunnels. 177.810 Section 177.810... Information and Regulations § 177.810 Vehicular tunnels. Except as regards Class 7 (radioactive) materials... through any urban vehicular tunnel used for mass transportation....

  1. 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..., DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.40 Tunnel sites....

  2. 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..., DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.40 Tunnel sites....

  3. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures shall...

  4. 49 CFR 177.810 - Vehicular tunnels.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Vehicular tunnels. 177.810 Section 177.810... Information and Regulations § 177.810 Vehicular tunnels. Except as regards Class 7 (radioactive) materials... through any urban vehicular tunnel used for mass transportation....

  5. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures shall...

  6. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures shall...

  7. 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..., DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.40 Tunnel sites....

  8. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures shall...

  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... Vehicular tunnels. Except as regards Class 7 (radioactive) materials, nothing contained in parts 170-189 of... tunnel used for mass transportation....

  10. 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..., DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.40 Tunnel sites....

  11. 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.

  12. Four-Nozzle Benchmark Wind Tunnel Model USA Code Solutions for Simulation of Multiple Rocket Base Flow Recirculation at 145,000 Feet Altitude

    NASA Technical Reports Server (NTRS)

    Dougherty, N. S.; Johnson, S. L.

    1993-01-01

    Multiple rocket exhaust plume interactions at high altitudes can produce base flow recirculation with attendant alteration of the base pressure coefficient and increased base heating. A search for a good wind tunnel benchmark problem to check grid clustering technique and turbulence modeling turned up the experiment done at AEDC in 1961 by Goethert and Matz on a 4.25-in. diameter domed missile base model with four rocket nozzles. This wind tunnel model with varied external bleed air flow for the base flow wake produced measured p/p(sub ref) at the center of the base as high as 3.3 due to plume flow recirculation back onto the base. At that time in 1961, relatively inexpensive experimentation with air at gamma = 1.4 and nozzle A(sub e)/A of 10.6 and theta(sub n) = 7.55 deg with P(sub c) = 155 psia simulated a LO2/LH2 rocket exhaust plume with gamma = 1.20, A(sub e)/A of 78 and P(sub c) about 1,000 psia. An array of base pressure taps on the aft dome gave a clear measurement of the plume recirculation effects at p(infinity) = 4.76 psfa corresponding to 145,000 ft altitude. Our CFD computations of the flow field with direct comparison of computed-versus-measured base pressure distribution (across the dome) provide detailed information on velocities and particle traces as well eddy viscosity in the base and nozzle region. The solution was obtained using a six-zone mesh with 284,000 grid points for one quadrant taking advantage of symmetry. Results are compared using a zero-equation algebraic and a one-equation pointwise R(sub t) turbulence model (work in progress). Good agreement with the experimental pressure data was obtained with both; and this benchmark showed the importance of: (1) proper grid clustering and (2) proper choice of turbulence modeling for rocket plume problems/recirculation at high altitude.

  13. 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

  14. 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).

  15. 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.

  16. [Modified Class II tunnel preparation].

    PubMed

    Rimondini, L; Baroni, C

    1991-05-15

    Tunnel preparations for restoration of Class II carious lesions in primary molars preserve the marginal ridge and minimize sacrifice of healthy tooth substructure. Materials with improved bonding to tooth structure and increase potential for fluoride release allow Class II restorations without "extension for prevention". PMID:1864420

  17. SCALING: Wind Tunnel to Flight

    NASA Astrophysics Data System (ADS)

    Bushnell, Dennis M.

    2006-01-01

    Wind tunnels have wide-ranging functionality, including many applications beyond aeronautics, and historically have been the major source of information for technological aerodynamics/aeronautical applications. There are a myriad of scaling issues/differences from flight to wind tunnel, and their study and impacts are uneven and a function of the particular type of extant flow phenomena. Typically, the most serious discrepancies are associated with flow separation. The tremendous ongoing increases in numerical simulation capability are changing and in many aspects have changed the function of the wind tunnel from a (scaled) "predictor" to a source of computational calibration/validation information with the computation then utilized as the flight prediction/scaling tool. Numerical simulations can increasingly include the influences of the various scaling issues. This wind tunnel role change has been occurring for decades as computational capability improves in all aspects. Additional issues driving this trend are the increasing cost (and time) disparity between physical experiments and computations, and increasingly stringent accuracy requirements.

  18. 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.

  19. 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…

  20. 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.

  1. The recurrent carpal tunnel syndrome.

    PubMed

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

    1993-01-01

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

  2. Tunneling in the SIS Structure

    NASA Astrophysics Data System (ADS)

    Shukrinov, Yu.; Kohandel, M.

    2000-09-01

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

  3. A seamless ubiquitous telehealthcare tunnel.

    PubMed

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

    2013-08-01

    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

  4. Tunneling time, what is its meaning?

    NASA Astrophysics Data System (ADS)

    McDonald, C. R.; Orlando, G.; Vampa, G.; Brabec, T.

    2015-03-01

    The tunnel time ionization dynamics for bound systems in laser fields are investigated. Numerical analysis for a step function switch-on of the field allows for the tunnel time to be defined as the time it takes the ground state to develop the under-barrier wavefunction components necessary to achieve the static field ionization rate. A relation between the tunnel time and the Keldysh time is established. The definition of the tunnel time is extended to time varying fields and experimental possibilities for measuring the tunnel time are discussed.

  5. Aeroelastic instability stoppers for wind tunnel models

    NASA Technical Reports Server (NTRS)

    Doggett, R. V., Jr.; Ricketts, R. H. (Inventor)

    1981-01-01

    A mechanism for diverting the flow in a wind tunnel from the wing of a tested model is described. The wing is mounted on the wall of a tunnel. A diverter plate is pivotally mounted on the tunnel wall ahead of the model. An actuator fixed to the tunnel is pivotably connected to the diverter plate, by plunger. When the model is about to become unstable during the test the actuator moves the diverter plate from the tunnel wall to divert maintaining stable model conditions. The diverter plate is then retracted to enable normal flow.

  6. 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

  7. 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.

  8. Harmonic multiplication using resonant tunneling

    NASA Technical Reports Server (NTRS)

    Sollner, T. C. L. G.; Brown, E. R.; Goodhue, W. D.; Correa, C. A.

    1988-01-01

    This paper demonstrates the use of resonant-tunneling diodes as varistors for harmonic multiplication. It is shown that efficient odd-harmonic conversion is possible and that even harmonics do not appear because of the antisymmetry of the current-voltage (I-V) curve. It is also shown that, with the proper choice of resonant-tunneling structure and pump amplitude, most of the harmonic output power can be confined to a single odd-harmonic frequency. Fifth-harmonic multiplication was demonstrated with an output at 21.75 GHz and a power conversion efficiency of 0.5 percent, and a fifth-harmonic efficiency of 2.7 percent was achieved in a circuit simulation using an improved I-V curve.

  9. Fermion tunneling from dynamical horizons

    NASA Astrophysics Data System (ADS)

    Di Criscienzo, R.; Vanzo, L.

    2008-06-01

    The instability against emission of fermionic particles by the trapping horizon of an evolving black hole is analyzed and confirmed using the Hamilton-Jacobi tunneling method. This method automatically selects one special expression for the surface gravity of a changing horizon. The results also apply to point masses embedded in an expanding universe. As a bonus of the tunneling method, we gain the insight that the surface gravity still defines a temperature parameter as long as the evolution is sufficiently slow that the black-hole pass through a sequence of quasi-equilibrium states, and that black holes should be semi-classically unstable even in a hypothetical world without bosonic fields.

  10. 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.

  11. Variable density turbulence tunnel facility.

    PubMed

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

    2014-09-01

    The Variable Density Turbulence Tunnel at the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany, produces very high turbulence levels at moderate flow velocities, low power consumption, and adjustable kinematic viscosity between 10(-4) m(2)/s and 10(-7) m(2)/s. The Reynolds number can be varied by changing the pressure or flow rate of the gas or by using different non-flammable gases including air. The highest kinematic viscosities, and hence lowest Reynolds numbers, are reached with air or nitrogen at 0.1 bar. To reach the highest Reynolds numbers the tunnel is pressurized to 15 bars with the dense gas sulfur hexafluoride (SF6). Turbulence is generated at the upstream ends of two measurement sections with grids, and the evolution of this turbulence is observed as it moves down the length of the sections. We describe the instrumentation presently in operation, which consists of the tunnel itself, classical grid turbulence generators, and state-of-the-art nano-fabricated hot-wire anemometers provided by Princeton University [M. Vallikivi, M. Hultmark, S. C. C. Bailey, and A. J. Smits, Exp. Fluids 51, 1521 (2011)]. We report measurements of the characteristic scales of the flow and of turbulent spectra up to Taylor Reynolds number R(λ) ≈ 1600, higher than any other grid-turbulence experiment. We also describe instrumentation under development, which includes an active grid and a Lagrangian particle tracking system that moves down the length of the tunnel with the mean flow. In this configuration, the properties of the turbulence are adjustable and its structure is resolvable up to R(λ) ≈ 8000.

  12. New treatment of quantum tunneling

    NASA Astrophysics Data System (ADS)

    Defendi, Antonio; Roncadelli, Marco

    1994-04-01

    We explore the implications of the recently proposed Langevin quantization for quantum tunneling, working within the semiclassical approximation. As far as we can see, the present treatment is simpler and more straightforward than the path integral approach. In fact, no extra trick is needed and the correct result follows at once - as a consequence of general principles - from the representation of the propagator supplied by the Langevin quantization. Further applications of the strategy discussed in this Letter are pointed out.

  13. Electrodiagnosis of carpal tunnel syndrome.

    PubMed

    Wang, Leilei

    2013-02-01

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

  14. Referral guidelines: carpal tunnel syndrome.

    PubMed

    Laws, E R

    1997-07-15

    The contribution on the postoperative management and rehabilitation of patients with carpal tunnel syndrome should be carefully considered by every surgeon. The operation is simply not over when the last stitch goes in; careful postoperative management is quite important if one is to obtain optimal surgical results. The principles outlined here are valuable and help to explain the occasional poor outcome. We have become convinced that the use of a dorsal splint in the 1st week to 10 days following surgery is a helpful measure. It is designed to prevent the median nerve from prolapsing forward and becoming adherent to or trapped by the edges of the severed transverse carpal ligament. With regard to surgical management of carpal tunnel syndrome. It is exceedingly important to continue producing outcome studies showing that our interventions really do eliminate the problem and allow people to return to productive work. Templates for outcome assessment are under development by the Outcomes Committee of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons and also by the American College of surgeons. Hopefully, they can be applied to the treatment of carpal tunnel syndrome. The following segment represents some suggested referral guidelines for patients with carpal tunnel syndrome. The present differential diagnosis, methods of confirming the diagnosis, and appropriate indications for considering surgery. These guidelines have been reviewed by the various authors who have contributed to this issue of Neurosurgical Focus and other colleagues in neurosurgery, orthopedics, plastic surgery, neurology, and occupational therapy. It is hoped that they will be a reasonable start in our efforts to inform referring physicians as to the nature of median thenar neuropathy and its overall management.

  15. 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. PMID:25128912

  16. Confocal Annular Josephson Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Monaco, Roberto

    2016-09-01

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

  17. Water jet assisted tunnel boring

    SciTech Connect

    Ozdemir, L.

    1984-06-21

    Mechanical tunnel boring has experienced significant growth over the last two decades. Improved machine design and performance coupled with a better understanding of factors affecting boreability have contributed to a dramatic increase in the number of machine bored tunnels. Today, tunnel boring machines (TBMs) are finding widespread application in various sectors of underground construction industry, both civil and mining. Most of the hard rock formations considered unsuited to mechanical boring only a few years ago are now excavated with TBMs with favorable economics compared to conventional drill and blast methods. Despite the advancements accomplished, TBMs need further improvements in design and operation to exend their capabilities and to reduce excavation costs, particularly in hard, abrasive rocks. The design of TBMs has presently reached a state where no additional major breakthroughs are anticipated in the near future. The cutter material appears to be the major obstacle to achieving further performance improvements. The amount of load which the cutters can sustain with acceptable levels of wear is the limiting factor determining the magnitude of the power that can be placed on a TBM. In fact, most present day TBMs can generate more thrust and torque than the individual cutters are capable of supporting.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. Homoepitaxial graphene tunnel barriers for spin transport

    NASA Astrophysics Data System (ADS)

    Friedman, Adam

    Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions (magnetic field, temperature, etc.) usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. We demonstrate successful tunneling, charge, and spin transport with a fluorinated graphene tunnel barrier on a graphene channel. We show that while spin transport stops short of room temperature, spin polarization efficiency values are the highest of any graphene spin devices. We also demonstrate that hydrogenation of graphene can also be used to create a tunnel barrier. We begin with a four-layer stack of graphene and hydrogenate the top few layers to decouple them from the graphene transport channel beneath. We demonstrate successful tunneling by measuring non-linear IV curves and a weakly temperature dependent zero-bias resistance. We demonstrate lateral transport of spin currents in non-local spin-valve structures and determine spin lifetimes with the non-local Hanle effect to be commensurate with previous studies. The measured spin polarization efficiencies for hydrogenated graphene are higher than most oxide tunnel barriers on graphene, but not as high as with fluorinated graphene tunnel barriers. However, here we show that spin transport persists up to room temperature. Our results for the hydrogenated graphene tunnel barriers are compared with fluorinated tunnel barriers and we discuss the

  7. Method of fabrication of Josephson tunnel junction

    SciTech Connect

    Michikami, O.; Katoh, Y.; Takenaka, H.; Tanabe, K.; Yoshii, S.

    1983-11-01

    There is disclosed a method of fabrication of a Josephson tunnel junction device. A surface of a base electrode of Nb or Nb compound is subjected to sputter cleaning and then to plasma oxidation in an atmosphere of a diluent gas and oxygen to form thereon an oxide layer serving as a tunnel barrier. A counter electrode is then formed on the oxide layer to provide the Josephson tunnel junction.

  8. Observation of density-induced tunneling.

    PubMed

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

    2014-11-01

    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.

  9. 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.

  10. Observation of density-induced tunneling.

    PubMed

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

    2014-11-01

    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. PMID:25415904

  11. Tunneling Ionization Time Resolved by Backpropagation.

    PubMed

    Ni, Hongcheng; Saalmann, Ulf; Rost, Jan-Michael

    2016-07-01

    We determine the ionization time in tunneling ionization by an elliptically polarized light pulse relative to its maximum. This is achieved by a full quantum propagation of the electron wave function forward in time, followed by a classical backpropagation to identify tunneling parameters, in particular, the fraction of electrons that has tunneled out. We find that the ionization time is close to zero for single active electrons in helium and in hydrogen if the fraction of tunneled electrons is large. We expect our analysis to be essential to quantify ionization times for correlated electron motion. PMID:27447504

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

    PubMed

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

    2005-12-01

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

  13. 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)

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  1. Acute carpal tunnel syndrome as a result of spontaneous bleeding

    PubMed Central

    Balakrishnan, Chenicheri; Jarrahnejad, Payam; Balakrishnan, Anila; Huettner, William C

    2008-01-01

    Acute carpal tunnel syndrome is the most common compression neuropathy of the upper extremity following trauma. A rare occurence of spontaneous bleeding into the carpal tunnel, presenting as acute carpal tunnel syndrome, is presented. PMID:19721797

  2. 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

  3. 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

  4. 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).

  5. 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)

  6. 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.

  7. 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

  8. Quantum tunneling beyond semiclassical approximation

    NASA Astrophysics Data System (ADS)

    Banerjee, Rabin; Ranjan Majhi, Bibhas

    2008-06-01

    Hawking radiation as tunneling by Hamilton-Jacobi method beyond semiclassical approximation is analysed. We compute all quantum corrections in the single particle action revealing that these are proportional to the usual semiclassical contribution. We show that a simple choice of the proportionality constants reproduces the one loop back reaction effect in the spacetime, found by conformal field theory methods, which modifies the Hawking temperature of the black hole. Using the law of black hole mechanics we give the corrections to the Bekenstein-Hawking area law following from the modified Hawking temperature. Some examples are explicitly worked out.

  9. Fermion tunneling beyond semiclassical approximation

    NASA Astrophysics Data System (ADS)

    Majhi, Bibhas Ranjan

    2009-02-01

    Applying the Hamilton-Jacobi method beyond the semiclassical approximation prescribed in R. Banerjee and B. R. Majhi, J. High Energy Phys.JHEPFG1029-8479 06 (2008) 09510.1088/1126-6708/2008/06/095 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.

  10. 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.

  11. Quantum temporal probabilities in tunneling systems

    SciTech Connect

    Anastopoulos, Charis Savvidou, Ntina

    2013-09-15

    We study the temporal aspects of quantum tunneling as manifested in time-of-arrival experiments in which the detected particle tunnels through a potential barrier. In particular, we present a general method for constructing temporal probabilities in tunneling systems that (i) defines ‘classical’ time observables for quantum systems and (ii) applies to relativistic particles interacting through quantum fields. We show that the relevant probabilities are defined in terms of specific correlation functions of the quantum field associated with tunneling particles. We construct a probability distribution with respect to the time of particle detection that contains all information about the temporal aspects of the tunneling process. In specific cases, this probability distribution leads to the definition of a delay time that, for parity-symmetric potentials, reduces to the phase time of Bohm and Wigner. We apply our results to piecewise constant potentials, by deriving the appropriate junction conditions on the points of discontinuity. For the double square potential, in particular, we demonstrate the existence of (at least) two physically relevant time parameters, the delay time and a decay rate that describes the escape of particles trapped in the inter-barrier region. Finally, we propose a resolution to the paradox of apparent superluminal velocities for tunneling particles. We demonstrate that the idea of faster-than-light speeds in tunneling follows from an inadmissible use of classical reasoning in the description of quantum systems. -- Highlights: •Present a general methodology for deriving temporal probabilities in tunneling systems. •Treatment applies to relativistic particles interacting through quantum fields. •Derive a new expression for tunneling time. •Identify new time parameters relevant to tunneling. •Propose a resolution of the superluminality paradox in tunneling.

  12. 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.

  13. Enhancement of tunnel magnetoresistance in magnetic tunnel junction by a superlattice barrier

    SciTech Connect

    Chen, C. H.; Hsueh, W. J.

    2014-01-27

    Tunnel magnetoresistance of magnetic tunnel junction improved by a superlattice barrier composed of alternate layers of a nonmagnetic metal and an insulator is proposed. The forbidden band of the superlattice is used to predict the low transmission range in the superlattice barrier. By forbidding electron transport in the anti-parallel configuration, the tunnel magnetoresistance is enhanced in the superlattice junction. The results show that the tunnel magnetoresistance ratio for a superlattice magnetic tunnel junction is greater than that for traditional single or double barrier junctions.

  14. 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…

  15. 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.

  16. 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…

  17. 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.

  18. 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.

  19. 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. PMID:16509375

  20. 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.

  1. 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.

  2. Tunnel Magnetoresistance and Temperature Related Effects in Magnetic Tunnel Junctions with Embedded Nanoparticles

    NASA Astrophysics Data System (ADS)

    Useinov, Arthur; Lai, Chih-Huang

    2016-02-01

    Temperature dependence of the tunnel magnetoresistance (TMR) was calculated in range of the quantum-ballistic model in the magnetic tunnel junction (MTJ) with embedded nanoparticles (NPs). The electron tunnel transport through NP was simulated in range of double barrier approach, which was integrated into the model of the magnetic point-like contact. The resonant TMR conditions and temperature impact were explored in detail. Moreover, the possible reasons of the temperature induced resonant conditions were discussed in the range of the lead-tunneling cell (TC)-lead model near Kondo temperature. We also found that redistribution of the voltage drop becomes crucial in this model. Furthermore, the direct tunneling plays the dominant role and cannot be omitted in the quantum systems with the total tunneling thickness up to 5-6nm. Hence, Coulomb blockade model cannot explain Kondo-induced TMR anomalies in nanometer-sized tunnel junctions.

  3. Hydrogen Tunneling in Enzyme Reactions

    NASA Astrophysics Data System (ADS)

    Cha, Yuan; Murray, Christopher J.; Klinman, Judith P.

    1989-03-01

    Primary and secondary protium-to-tritium (H/T) and deuterium-to-tritium (D/T) kinetic isotope effects for the catalytic oxidation of benzyl alcohol to benzaldehyde by yeast alcohol dehydrogenase (YADH) at 25 degrees Celsius have been determined. Previous studies showed that this reaction is nearly or fully rate limited by the hydrogen-transfer step. Semiclassical mass considerations that do not include tunneling effects would predict that kH/kT = (kD/kT)3.26, where kH, kD, and kT are the rate constants for the reaction of protium, deuterium, and tritium derivatives, respectively. Significant deviations from this relation have now been observed for both primary and especially secondary effects, such that experimental H/T ratios are much greater than those calculated from the above expression. These deviations also hold in the temperature range from 0 to 40 degrees Celsius. Such deviations were previously predicted to result from a reaction coordinate containing a significant contribution from hydrogen tunneling.

  4. Hydrogen tunneling in enzyme reactions.

    PubMed

    Cha, Y; Murray, C J; Klinman, J P

    1989-03-10

    Primary and secondary protium-to-tritium (H/T) and deuterium-to-tritium (D/T) kinetic isotope effects for the catalytic oxidation of benzyl alcohol to benzaldehyde by yeast alcohol dehydrogenase (YADH) at 25 degrees Celsius have been determined. Previous studies showed that this reaction is nearly or fully rate limited by the hydrogen-transfer step. Semiclassical mass considerations that do not include tunneling effects would predict that kH/kT = (kD/kT)3.26, where kH, kD, and kT are the rate constants for the reaction of protium, deuterium, and tritium derivatives, respectively. Significant deviations from this relation have now been observed for both primary and especially secondary effects, such that experimental H/T ratios are much greater than those calculated from the above expression. These deviations also hold in the temperature range from 0 to 40 degrees Celsius. Such deviations were previously predicted to result from a reaction coordinate containing a significant contribution from hydrogen tunneling.

  5. 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)

  6. 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.

  7. High Surface Area Tunnels in Hexagonal WO₃.

    PubMed

    Sun, Wanmei; Yeung, Michael T; Lech, Andrew T; Lin, Cheng-Wei; Lee, Chain; Li, Tianqi; Duan, Xiangfeng; Zhou, Jun; Kaner, Richard B

    2015-07-01

    High surface area in h-WO3 has been verified from the intracrystalline tunnels. This bottom-up approach differs from conventional templating-type methods. The 3.67 Å diameter tunnels are characterized by low-pressure CO2 adsorption isotherms with nonlocal density functional theory fitting, transmission electron microscopy, and thermal gravimetric analysis. These open and rigid tunnels absorb H(+) and Li(+), but not Na(+) in aqueous electrolytes without inducing a phase transformation, accessing both internal and external active sites. Moreover, these tunnel structures demonstrate high specific pseudocapacitance and good stability in an H2SO4 aqueous electrolyte. Thus, the high surface area created from 3.67 Å diameter tunnels in h-WO3 shows potential applications in electrochemical energy storage, selective ion transfer, and selective gas adsorption.

  8. Aberrant Radial Artery Causing Carpal Tunnel Syndrome

    PubMed Central

    Kokkalis, Zinon T.; Tolis, Konstantinos E.; Megaloikonomos, Panayiotis D.; Panagopoulos, Georgios N.; Igoumenou, Vasilios G.; Mavrogenis, Andreas F.

    2016-01-01

    Anatomical vascular variations are rare causes of carpal tunnel syndrome. An aberrant medial artery is the most common vascular variation, while an aberrant radial artery causing carpal tunnel syndrome is even more rare, with an incidence ranging less than 3%. This article reports a patient with compression of the median nerve at the carpal tunnel by an aberrant superficial branch of the radial artery. An 80- year- old man presented with a 5-year history of right hand carpal tunnel syndrome; Tinel sign, Phalen test and neurophysiological studies were positive. Open carpal tunnel release showed an aberrant superficial branch of the radial artery with its accompanying veins running from radially to medially, almost parallel to the median nerve, ending at the superficial palmar arterial arch. The median nerve was decompressed without ligating the aberrant artery. At the last follow-up, 2 years after diagnosis and treatment the patient is asymptomatic. PMID:27517078

  9. Aberrant Radial Artery Causing Carpal Tunnel Syndrome.

    PubMed

    Kokkalis, Zinon T; Tolis, Konstantinos E; Megaloikonomos, Panayiotis D; Panagopoulos, Georgios N; Igoumenou, Vasilios G; Mavrogenis, Andreas F

    2016-06-01

    Anatomical vascular variations are rare causes of carpal tunnel syndrome. An aberrant medial artery is the most common vascular variation, while an aberrant radial artery causing carpal tunnel syndrome is even more rare, with an incidence ranging less than 3%. This article reports a patient with compression of the median nerve at the carpal tunnel by an aberrant superficial branch of the radial artery. An 80- year- old man presented with a 5-year history of right hand carpal tunnel syndrome; Tinel sign, Phalen test and neurophysiological studies were positive. Open carpal tunnel release showed an aberrant superficial branch of the radial artery with its accompanying veins running from radially to medially, almost parallel to the median nerve, ending at the superficial palmar arterial arch. The median nerve was decompressed without ligating the aberrant artery. At the last follow-up, 2 years after diagnosis and treatment the patient is asymptomatic.

  10. The path decomposition expansion and multidimensional tunneling

    NASA Astrophysics Data System (ADS)

    Auerbach, Assa; Kivelson, S.

    This paper consists of two main topics. (i) The path decomposition expansion: a new path integral technique which allows us to break configuration space into disjoint regions and express the dynamics of the full system in terms of its parts. (ii) The application of the PDX and semiclassical methods for solving quantum-mechanical tunneling problems in multidimensions. The result is a conceptually simple, computationally straightforward method for calculating tunneling effects in complicated multidimensional potentials, even in cases where the nature of the states in the classically allowed regions is nontrivial. Algorithms for computing tunneling effects in general classes of problems are obtained.In addition, we present the detailed solutions to three model problems of a tunneling coordinate coupled to a phonon. This enables us to define various well-controlled approximation schemes, which help to reduce the dimensions of complicated tunneling calculations in real physical systems.

  11. Aberrant Radial Artery Causing Carpal Tunnel Syndrome.

    PubMed

    Kokkalis, Zinon T; Tolis, Konstantinos E; Megaloikonomos, Panayiotis D; Panagopoulos, Georgios N; Igoumenou, Vasilios G; Mavrogenis, Andreas F

    2016-06-01

    Anatomical vascular variations are rare causes of carpal tunnel syndrome. An aberrant medial artery is the most common vascular variation, while an aberrant radial artery causing carpal tunnel syndrome is even more rare, with an incidence ranging less than 3%. This article reports a patient with compression of the median nerve at the carpal tunnel by an aberrant superficial branch of the radial artery. An 80- year- old man presented with a 5-year history of right hand carpal tunnel syndrome; Tinel sign, Phalen test and neurophysiological studies were positive. Open carpal tunnel release showed an aberrant superficial branch of the radial artery with its accompanying veins running from radially to medially, almost parallel to the median nerve, ending at the superficial palmar arterial arch. The median nerve was decompressed without ligating the aberrant artery. At the last follow-up, 2 years after diagnosis and treatment the patient is asymptomatic. PMID:27517078

  12. Carpal tunnel syndrome among ski manufacturing workers.

    PubMed

    Barnhart, S; Demers, P A; Miller, M; Longstreth, W T; Rosenstock, L

    1991-02-01

    Carpal tunnel syndrome is a common disorder marked by pain and dysesthesias of the upper extremities. As a test of the hypothesis that carpal tunnel syndrome is associated with occupational risk factors, jobs at a ski assembly plant were classified as repetitive and nonrepetitive. The prevalence of carpal tunnel syndrome among 106 employees with repetitive jobs was compared with that among 67 employees with nonrepetitive jobs. The data collection included a questionnaire, a physical examination, and the measurement of distal sensory latencies of the median and ulnar nerves. Carpal tunnel syndrome was present in either or both hands in 15.4% of those workers with repetitive jobs, but only in 3.1% of those workers with nonrepetitive jobs (crude prevalence ratio 4.92, 95% confidence interval 1.17-20.7). The conclusion was drawn that carpal tunnel syndrome is associated with jobs requiring frequent and sustained hand work.

  13. 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.

  14. 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.

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

    PubMed

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

    2011-03-01

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

  16. 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

  17. Update: Partnership for the Revitalization of National Wind Tunnel Force Measurement Technology Capability

    NASA Technical Reports Server (NTRS)

    Rhew, Ray D.

    2010-01-01

    NASA's Aeronautics Test Program (ATP) chartered a team to examine the issues and risks associated with the lack of funding and focus on force measurement over the past several years, focusing specifically on strain-gage balances. NASA partnered with the U.S. Air Force's Arnold Engineering Development Center (AEDC) to exploit their combined capabilities and take a national level government view of the problem and established the National Force Measurement Technology Capability (NFMTC) project. This paper provides an update on the team's status for revitalizing the government's balance capability with respect to designing, fabricating, calibrating, and using the these critical measurement devices.

  18. 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.

  19. SSX MHD plasma wind tunnel

    NASA Astrophysics Data System (ADS)

    Brown, Michael R.; Schaffner, David A.

    2015-06-01

    A new turbulent plasma source at the Swarthmore Spheromak Experiment (SSX) facility is described. The MHD wind tunnel configuration employs a magnetized plasma gun to inject high-beta plasma into a large, well-instrumented, vacuum drift region. This provides unique laboratory conditions approaching that in the solar wind: there is no applied background magnetic field in the drift region and has no net axial magnetic flux; the plasma flow speed is on the order of the local sound speed (M ~ 1), so flow energy density is comparable to thermal energy density; and the ratio of thermal to magnetic pressure is of order unity (plasma β ~ 1) so thermal energy density is also comparable to magnetic energy density. Results presented here and referenced within demonstrate the new capabilities and show how the new platform is proving useful for fundamental plasma turbulence studies.

  20. 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

  1. 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.

  2. Tunneling magnetoresistance of silicon chains

    NASA Astrophysics Data System (ADS)

    Matsuura, Yukihito

    2016-05-01

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

  3. 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.

  4. Quantum tunneling with global charge

    SciTech Connect

    Lee, K. )

    1994-10-15

    We investigate quantum tunneling in the theory of a complex scalar field with a global U(1) symmetry when the charge density of the initial configuration does not vanish. We discuss the possible final configurations and set up the Euclidean path integral formalism to find the bubble nucleation and to study the bubble evolution. For the stationary path, or the bounce solution, in the Euclidean time, the phase variable becomes pure imaginary so that the charge density remains real. We apply this formalism to examples when the initial charge density is small. While the phase transition considered here occurs in zero temperature, the bubble dynamics is richly complicated, involving conserved charge, the sound wave, and the supersonic bubble wall.

  5. Giant tunneling magnetoresistance in silicene

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Lou, Yiyi

    2013-11-01

    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.

  6. 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.

  7. Homoepitaxial graphene tunnel barriers for spin transport

    NASA Astrophysics Data System (ADS)

    Friedman, Adam L.; van't Erve, Olaf M. J.; Robinson, Jeremy T.; Whitener, Keith E.; Jonker, Berend T.

    2016-05-01

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

  8. 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.

  9. Tunneling of a heavily damped macroscopic variable

    SciTech Connect

    Schwartz, D.B.

    1987-01-01

    The author studied the effect of damping upon fluxoid transitions in simple microfabricated circuits consisting of an inductor and small-area Josephson tunnel junctions. In order to provide an easily characterized source of damping, the tunnel junctions were fabricated with low-inductance resistive shunts across them. To keep tunneling from being suppressed to unreachably low temperatures, the samples were designed to exhibit tunneling at high temperatures in the absence of damping. This was achieved by having junction areas of approximately 0.1 ..mu../sup 2/, which pushes the characteristic time scales to over 10/sup 12/ s/sup -1/. Tunneling was unambiguously observed at 2K in the unshunted samples. The temperature where thermal activation won over tunneling in determining the escape rate was suppressed by an order of magnitude in the shunted samples, in good agreement with theoretical predictions. The predicted T/sup 2/ dependence of the exponent of the tunneling rate upon temperature was also clearly observed in the data. At temperatures where thermal activation dominates the escape-rate quantum corrections to the escape rate are predicted. Analysis of these effects upon the data is complicated by the high frequencies involved. Although the data does not constitute a clear test of these corrections, it seems clear that simple thermal activation without quantum corrections does not suffice to explain it.

  10. Quantum temporal probabilities in tunneling systems

    NASA Astrophysics Data System (ADS)

    Anastopoulos, Charis; Savvidou, Ntina

    2013-09-01

    We study the temporal aspects of quantum tunneling as manifested in time-of-arrival experiments in which the detected particle tunnels through a potential barrier. In particular, we present a general method for constructing temporal probabilities in tunneling systems that (i) defines 'classical' time observables for quantum systems and (ii) applies to relativistic particles interacting through quantum fields. We show that the relevant probabilities are defined in terms of specific correlation functions of the quantum field associated with tunneling particles. We construct a probability distribution with respect to the time of particle detection that contains all information about the temporal aspects of the tunneling process. In specific cases, this probability distribution leads to the definition of a delay time that, for parity-symmetric potentials, reduces to the phase time of Bohm and Wigner. We apply our results to piecewise constant potentials, by deriving the appropriate junction conditions on the points of discontinuity. For the double square potential, in particular, we demonstrate the existence of (at least) two physically relevant time parameters, the delay time and a decay rate that describes the escape of particles trapped in the inter-barrier region. Finally, we propose a resolution to the paradox of apparent superluminal velocities for tunneling particles. We demonstrate that the idea of faster-than-light speeds in tunneling follows from an inadmissible use of classical reasoning in the description of quantum systems.

  11. Pair Tunneling through Single Molecules

    NASA Astrophysics Data System (ADS)

    Raikh, Mikhail

    2007-03-01

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

  12. Distance metrics for heme protein electron tunneling.

    PubMed

    Moser, Christopher C; Chobot, Sarah E; Page, Christopher C; Dutton, P Leslie

    2008-01-01

    There is no doubt that distance is the principal parameter that sets the order of magnitude for electron-tunneling rates in proteins. However, there continue to be varying ways to measure electron-tunneling distances in proteins. This distance uncertainty blurs the issue of whether the intervening protein medium has been naturally selected to speed or slow any particular electron-tunneling reaction. For redox cofactors lacking metals, an edge of the cofactor can be defined that approximates the extent in space that includes most of the wavefunction associated with its tunneling electron. Beyond this edge, the wavefunction tails off much more dramatically in space. The conjugated porphyrin ring seems a reasonable edge for the metal-free pheophytins and bacteriopheophytins of photosynthesis. For a metal containing redox cofactor such as heme, an appropriate cofactor edge is more ambiguous. Electron-tunneling distance may be measured from the conjugated heme macrocycle edge or from the metal, which can be up to 4.8 A longer. In a typical protein medium, such a distance difference normally corresponds to a approximately 1000 fold decrease in tunneling rate. To address this ambiguity, we consider both natural heme protein electron transfer and light-activated electron transfer in ruthenated heme proteins. We find that the edge of the conjugated heme macrocycle provides a reliable and useful tunneling distance definition consistent with other biological electron-tunneling reactions. Furthermore, with this distance metric, heme axially- and edge-oriented electron transfers appear similar and equally well described by a simple square barrier tunneling model. This is in contrast to recent reports for metal-to-metal metrics that require exceptionally poor donor/acceptor couplings to explain heme axially-oriented electron transfers.

  13. Dynamical quenching of tunneling in molecular magnets

    NASA Astrophysics Data System (ADS)

    José Santander, María; Nunez, Alvaro S.; Roldán-Molina, A.; Troncoso, Roberto E.

    2015-12-01

    It is shown that a single molecular magnet placed in a rapidly oscillating magnetic field displays the phenomenon of quenching of tunneling processes. The results open a way to manipulate the quantum states of molecular magnets by means of radiation in the terahertz range. Our analysis separates the time evolution into slow and fast components thereby obtaining an effective theory for the slow dynamics. This effective theory presents quenching of the tunnel effect, in particular, stands out its difference with the so-called coherent destruction of tunneling. We support our prediction with numerical evidence based on an exact solution of Schrödinger's equation.

  14. Other cryogenic wind-tunnel projects

    NASA Technical Reports Server (NTRS)

    Kilgore, R. A.

    1985-01-01

    Following the development of the cryogenic wind tunnel at the NASA Langley Research Center in 1972, a large number of cryogenic wind-tunnel projects have been undertaken at various research establishments around the world. Described in this lecture are cryogenic wind-tunnel projects in China (Chinese Aeronautical Research and Development Center), England (College of Aeronautics at Cranfield, Royal Aircraft Establishment - Bedford, and University of Southampton), Japan (National Aerospace Laboratory, University of Tsukuba, and National Defense Academy), Sweden (Rollab), and the United States (Douglas Aircraft Co., University of Illinois at Urbana-Champaign, and NASA Langley).

  15. Mechanical tunnel excavation in welded tuff

    SciTech Connect

    Sperry, P.E.

    1991-12-31

    The Technical Review Board for the US high-level radioactive waste facility at Yucca Mountain has recommended maximum use of {open_quotes}the most modern mechanical excavation techniques...in order to reduce disturbance to the rock walls and to achieve greater economy of time and cost.{close_quotes} Tunnels for the waste repository at Yucca Mountain can be economically constructed with mechanical excavation equipment. This paper presents the results of mechanical excavation of a tunnel in welded tuff, similar to the tuffs of Yucca Mountain. These results are projected to excavation of emplacement drifts in Yucca Mountain using a current state-of-the-art tunnel boring machine (TBM).

  16. A wind tunnel database using RIM

    NASA Technical Reports Server (NTRS)

    Wray, W. O., Jr.

    1984-01-01

    Engineering data base development which has become increasingly widespread to industry with the availability of data management systems is examined. A large data base was developed for wind tunnel data and related model test information, using RIM as the data base manager. The arrangement of the wind tunnel data into the proper schema for the most efficient database utilization is discussed. The FORTRAN interface program of RIM is used extensively in the loading phases of the data base and by the users. Several examples to illustrate how the Wind Tunnel Data base might be searched for specific data items and test information using RIM are presented.

  17. 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

  18. 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.

  19. Water tunnel flow visualization using a laser

    NASA Technical Reports Server (NTRS)

    Beckner, C.; Curry, R. E.

    1985-01-01

    Laser systems for flow visualization in water tunnels (similar to the vapor screen technique used in wind tunnels) can provide two-dimensional cross-sectional views of complex flow fields. This parametric study documents the practical application of the laser-enhanced visualization (LEV) technique to water tunnel testing. Aspects of the study include laser power levels, flow seeding (using flourescent dyes and embedded particulates), model preparation, and photographic techniques. The results of this study are discussed to provide potential users with basic information to aid in the design and setup of an LEV system.

  20. 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.

  1. 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... MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.41 What is a tunnel site? A tunnel site is a subsurface right-of-way under Federal...

  2. 30 CFR 77.213 - Draw-off tunnel escapeways.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Draw-off tunnel escapeways. 77.213 Section 77... Surface Installations § 77.213 Draw-off tunnel escapeways. When it is necessary for a tunnel to be closed... tunnel to a safe location on the surface; and, if the escapeway is inclined more than 30 degrees from...

  3. 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

  4. 30 CFR 77.213 - Draw-off tunnel escapeways.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Draw-off tunnel escapeways. 77.213 Section 77... Surface Installations § 77.213 Draw-off tunnel escapeways. When it is necessary for a tunnel to be closed... tunnel to a safe location on the surface; and, if the escapeway is inclined more than 30 degrees from...

  5. 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

  6. 30 CFR 77.213 - Draw-off tunnel escapeways.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Draw-off tunnel escapeways. 77.213 Section 77... Surface Installations § 77.213 Draw-off tunnel escapeways. When it is necessary for a tunnel to be closed... tunnel to a safe location on the surface; and, if the escapeway is inclined more than 30 degrees from...

  7. 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

  8. 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

  9. 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... MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LOCATING MINING CLAIMS OR SITES Tunnel Sites § 3832.41 What is a tunnel site? A tunnel site is a subsurface right-of-way under Federal...

  10. 30 CFR 77.213 - Draw-off tunnel escapeways.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Draw-off tunnel escapeways. 77.213 Section 77... Surface Installations § 77.213 Draw-off tunnel escapeways. When it is necessary for a tunnel to be closed... tunnel to a safe location on the surface; and, if the escapeway is inclined more than 30 degrees from...

  11. 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

  12. 30 CFR 77.213 - Draw-off tunnel escapeways.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Draw-off tunnel escapeways. 77.213 Section 77... Surface Installations § 77.213 Draw-off tunnel escapeways. When it is necessary for a tunnel to be closed... tunnel to a safe location on the surface; and, if the escapeway is inclined more than 30 degrees from...

  13. 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

  14. 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

  15. 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

  16. 47 CFR 15.211 - Tunnel radio systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... surrounding earth and/or water. (b) Any intentional or unintentional radiator external to the tunnel, mine or... 47 Telecommunication 1 2013-10-01 2013-10-01 false Tunnel radio systems. 15.211 Section 15.211... Tunnel radio systems. An intentional radiator utilized as part of a tunnel radio system may operate...

  17. 47 CFR 15.211 - Tunnel radio systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... surrounding earth and/or water. (b) Any intentional or unintentional radiator external to the tunnel, mine or... 47 Telecommunication 1 2011-10-01 2011-10-01 false Tunnel radio systems. 15.211 Section 15.211... Tunnel radio systems. An intentional radiator utilized as part of a tunnel radio system may operate...

  18. 47 CFR 15.211 - Tunnel radio systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... surrounding earth and/or water. (b) Any intentional or unintentional radiator external to the tunnel, mine or... 47 Telecommunication 1 2014-10-01 2014-10-01 false Tunnel radio systems. 15.211 Section 15.211... Tunnel radio systems. An intentional radiator utilized as part of a tunnel radio system may operate...

  19. 47 CFR 15.211 - Tunnel radio systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... surrounding earth and/or water. (b) Any intentional or unintentional radiator external to the tunnel, mine or... 47 Telecommunication 1 2012-10-01 2012-10-01 false Tunnel radio systems. 15.211 Section 15.211... Tunnel radio systems. An intentional radiator utilized as part of a tunnel radio system may operate...

  20. 47 CFR 15.211 - Tunnel radio systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... surrounding earth and/or water. (b) Any intentional or unintentional radiator external to the tunnel, mine or... 47 Telecommunication 1 2010-10-01 2010-10-01 false Tunnel radio systems. 15.211 Section 15.211... Tunnel radio systems. An intentional radiator utilized as part of a tunnel radio system may operate...

  1. 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.

  2. 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.

  3. High Magnetoresistance in Fully Epitaxial Magnetic Tunnel Junctions with a Semiconducting GaOx Tunnel Barrier

    NASA Astrophysics Data System (ADS)

    Matsuo, Norihiro; Doko, Naoki; Takada, Tetsuro; Saito, Hidekazu; Yuasa, Shinji

    2016-09-01

    We fabricate magnetic tunnel junctions with fully epitaxial Fe (001 )/GaOx(001 )/Fe (001 ) structure, where the GaOx is a wide band-gap semiconductor with a cubic spinel-type crystal structure. Tunneling magnetoresistance ratios up to 92% (125%) are observed at room temperature (20 K), which evidently indicates the existence of a spin-polarized coherent tunneling. The observed MR ratio is the highest among the reported magnetic tunnel junctions with a semiconducting tunnel barrier and ferromagnetic metal electrodes. Such a single-crystalline semiconductor tunnel barrier that shows a high MR ratio is an essential building block for a vertical-type spin field-effect transistor.

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

    DOEpatents

    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.

  5. The cryogenic wind tunnel for high Reynolds number testing

    NASA Technical Reports Server (NTRS)

    Kilgore, R. A.; Dress, D. A.

    1982-01-01

    The development of cryogenic wind tunnels is reviewed with reference to the theory and advantages of cryogenic tunnels, problems common to wind tunnels and their solution, and application of cryogenic wind tunnels to high Reynolds number testing. It is shown that cryogenic wind tunnels can achieve full-scale Reynolds number with reasonable tunnel size, dynamic pressure, and drive power; the use of such tunnels also makes it possible to separate the effects of Reynolds number, Mach number, and aeroelasticity. Application of the cryogenic tunnel concept is illustrated by three examples, namely an atmospheric low-speed cryogenic tunnel, a 0.3-meter transonic cryogenic tunnel, and the National Transonic Facility now nearing completion.

  6. 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

  7. Fermi resonance in dynamical tunneling in a chaotic billiard

    NASA Astrophysics Data System (ADS)

    Yi, Chang-Hwan; Kim, Ji-Hwan; Yu, Hyeon-Hye; Lee, Ji-Won; Kim, Chil-Min

    2015-08-01

    We elucidate that Fermi resonance ever plays a decisive role in dynamical tunneling in a chaotic billiard. Interacting with each other through an avoided crossing, a pair of eigenfunctions are coupled through tunneling channels for dynamical tunneling. In this case, the tunneling channels are an islands chain and its pair unstable periodic orbit, which equals the quantum number difference of the eigenfunctions. This phenomenon of dynamical tunneling is confirmed in a quadrupole billiard in relation with Fermi resonance.

  8. Tunnel magnetoresistance in Self-Assembled Monolayers Based Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Mattana, Richard; Barraud, Clément; Tatay, Sergio; Galbiati, Marta; Seneor, Pierre; Bouzehouane, Karim; Jacquet, Eric; Deranlot, Cyrile; Fert, Albert; Petroff, Frédéric

    2012-02-01

    Organic/molecular spintronics is a rising research field at the frontier between spintronics and organic chemistry. Organic molecule and semiconductors were first seen as promising for spintronics devices due to their expected long spin lifetime. But an exciting challenge has also been to find opportunities arising from chemistry to develop new spintronics functionalities. It was shown that the molecular structure and the ferromagnetic metal/molecule hybridization can strongly influence interfacial spin properties going from spin polarization enhancement to its sign control in spintronics devices. In this scenario, while scarcely studied, self-assembled monolayers (SAMs) are expected to become perfect toy barriers to further test these tailoring properties in molecular magnetic tunnel junctions (MTJs). Due to its very high spin polarization and air stability LSMO has positioned itself as the electrode of choice in most of the organic spintronics devices. We will present a missing building block for molecular spintronics tailoring: the grafting and film characterization of organic monofunctionalized long alkane chains over LSMO. We have obtained 35% of magnetoresistance in LSMO/SAMs/Co MTJs. We will discuss the unusual behaviour of the bias voltage dependence of the TMR.

  9. 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.

  10. Thermodynamics of phonon-modulated tunneling centers

    SciTech Connect

    Junker, W.; Wagner, M. )

    1989-08-01

    In recent years tunneling centers have frequently been used to explain the unusual thermodynamic properties of disordered materials; in these approaches, however, the effect of the tunneling-phonon interaction is neglected. The present study considers the archetype model of phono-assisted tunneling, which is well known from other areas of tunneling physics (quantum diffusion, etc.). It is shown that the full thermodynamic information can be rigorously extracted from a single Green function. An extended factorization procedure beyond Hartree-Fock is introduced, which is checked by sum rules as well as by exact Goldberger-Adams expansions. The phonon-modulated internal energy and specific heat are calculated for different power-law coupling setups.

  11. Decoherence and tunneling of an interacting gas

    NASA Astrophysics Data System (ADS)

    Anglin, James; Rico-Perez, Luis; Wohlfarth, Daniel

    2015-05-01

    In quasi-steady escape of a confined interacting gas by quantum tunneling, collisional decoherence can reduce the escape rate through a many-body version of the Caldeira-Leggett effect. This explains why classical fluids fail to tunnel, even though they are composed of particles small enough to be quantum mechanical. We compute this effect in the Maxwell-Boltzmann regime by deriving a quantum generalization of the Boltzmann equation. We show that decoherence effectively makes tunneling of an interacting gas into an irreversible process: a uniquely quantum mechanical form of throttling. The rate of entropy production in tunneling is related in the semi-classical limit to the imaginary part of the single-particle action.

  12. Tertiary Interactions within the Ribosomal Exit Tunnel

    PubMed Central

    Kosolapov, Andrey; Deutsch, Carol

    2009-01-01

    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 β-hairpin as well as an α-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. PMID:19270700

  13. 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.

  14. Resonant tunneling of carriers in silicon nanocrystals

    NASA Astrophysics Data System (ADS)

    Derbenyova, N. V.; Konakov, A. A.; Burdov, V. A.

    2016-10-01

    The rates of resonant and nearly resonant tunnel transitions have been calculated within the envelope function approximation for electrons and holes in silicon nanocrystals embedded in a silicon dioxide matrix. It is shown that, if the nanocrystals are close enough, the rates of resonant tunneling reach the values of the order of 1012-1014 s-1, which considerably exceed the rates of radiative recombination and other basic non-radiative processes, such as the Auger recombination and capture on surface defects. The transition rate is found to be very sensitive to inter-crystallite distance, crystallite size, and effective mass of the carriers in the oxide matrix. Electron tunneling turns out to be faster than the hole one, especially, at greater distances between the nanocrystals. Thus, the tunnel migration in a dense ensemble of nanocrystals is mainly electronic.

  15. 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 dimensional to large-scale models of complete aircraft configurations. Model sizing, power simulation, and planning are treated, including three areas in test operations: data acquisition systems, acoustic measurements in wind tunnels, and flow surveying.

  16. Scanning tunneling microscopy imaging of nanotubes

    SciTech Connect

    Antonenko, S. V. Malinovskaya, O. S.; Mal'tsev, S. N.

    2007-07-15

    Samples of carbon paper containing multiwalled carbon nanotube films are produced by current annealing. A scanning tunneling microscope is used to examine the structure of the modified carbon paper. X-, Y-, and V-shaped nanotubes are found.

  17. 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)

  18. 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.

  19. On a new type of wind tunnel

    NASA Technical Reports Server (NTRS)

    Munk, Max

    1921-01-01

    Discussed here is a new type of wind tunnel, its advantages, the difficulties attendant upon its use, and the special methods required for its operation. The main difference between the new type of wind tunnel and the ones now in operation is the use of a different fluid. The idea is to diminish the effect of viscosity If air is compressed, it becomes a fluid with new properties - a fluid that is best suited for reliable and exact tests on models. When air is compressed, its density increases, but its viscosity does not. It is argued that the increase of pressure greatly increases the range and value of wind tunnel tests. Reynolds number, deductions from the Reynolds law, the causes of errors that result in differences between tests on models and actual flights, and the dimensions of a compressed air wind tunnel are covered.

  20. Spin Valves and Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Iversen, Kurt; Pufall, Matthew; Heindl, Ranko

    2011-10-01

    This is a presentation of research conducted through the National Institute of Standards and Technology's Summer Undergraduate Research Fellowship program. A spintronic device is one that uses the electron's magnetic moment (its spin) as well as its charge to perform operations, such as data storage or logic. Many of today's spintronic devices are based on the ``tunneling magnetoresistance'' effect of CoFeB/MgO/CoFeB tunnel junctions. The MgO barrier in devices must be highly uniform and only 1-2 nm thick. Relevant background, including electron spin and tunneling, is supplied. The fabrication, operation, and behavior of spin-valves and magnetic tunnel junctions are described, and applications in Hard Disk Drives, Magnetic Random Access Memory, Magnetic Field Sensors, and Spin-Torque Oscillators are discussed.

  1. Wind tunnel buffet load measuring technique

    NASA Technical Reports Server (NTRS)

    Chang, C. S.; Ellison, A. M.

    1972-01-01

    Indirect force measurement technique estimates unsteady forces acting on elastic model during wind tunnel tests. Measurement of forces is practically insensitive to errors in aeroelastic scaling between model and full-scale structure, simplifying design, fabrication and dynamic calibration.

  2. 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.

  3. Tunneling rate in double quantum dots

    NASA Astrophysics Data System (ADS)

    Filikhin, Igor; Matinyan, Sergei; Vlahovic, Branislav

    2014-03-01

    We study spectral properties of electron tunneling in double quantum dots (DQDs) (and double quantum wells (DQWs)) and their relation to the geometry. In particular we compare the tunneling in DQW with chaotic and regular geometry, taking into account recent evidence about regularization of the tunneling rate when the QW geometry is chaotic. Our calculations do not support this assumption. We confirm high influence of the QW geometry boundaries on the rate fluctuation along the spectrum. The factors of the effective mass anisotropy and violation of the symmetry of DQD and DQW are also considered. Generally, we found that the small violation of the symmetry drastically affects tunneling. This work is supported by the NSF (HRD-0833184) and NASA (NNX09AV07A).

  4. Resonant Tunneling in Double Bilayer Graphene Heterostructures

    NASA Astrophysics Data System (ADS)

    Fallahazad, Babak; Lee, Kayoung; Kang, Sangwoo; Xue, Jiamin; Larentis, Stefano; Corbet, Christopher; Kim, Kyounghwan; Movva, Hema; Taniguchi, Takashi; Watanabe, Kenji; Register, Leonard; Banerjee, Sanjay; Tutuc, Emanuel

    2015-03-01

    We present the realization and characterization of independently contacted and rotationally aligned double bilayer graphene heterostructures, that show gate-tunable tunneling resonances and negative differential resistance in their interlayer current-voltage characteristics. Our devices are fabricated by successively stacking mechanically exfoliated bilayer graphene and hexagonal boron nitride dielectric using a layer-by-layer transfer technique. The bilayers are rotationally aligned during the device fabrication by selecting flakes with straight edges, and using them as a reference for alignment. We determine the heterostructure energy band alignment at the tunneling resonance using the individual layer carrier densities, and including the chemical potential dependence on the carrier density. Our analysis show that the tunneling resonances occur when the charge neutrality points of the two bilayer graphene are energetically aligned, which suggests the resonances stem from the momentum conserving tunneling. This work has been supported by NRI-SWAN, ONR, and Intel.

  5. 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

  6. 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...

  7. 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...

  8. Modeling direct interband tunneling. I. Bulk semiconductors

    SciTech Connect

    Pan, Andrew; Chui, Chi On

    2014-08-07

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

  9. Advanced Canard in 12 Foot Tunnel

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Advanced-concepts model plane with front canards, winglets and pusher propellers, in 12 Foot Low-Speed Tunnel. Photograph published in Winds of Change, 75th Anniversary NASA publication, (page 12), by James Schultz.

  10. Two-Dimensional Low-Turbulence Tunnel

    NASA Technical Reports Server (NTRS)

    1937-01-01

    Construction of the Two-Dimensional Low-Turbulence Tunnel. The Two-Dimensional Low-Turbulence Tunnel was originally called the Refrigeration or 'Ice' tunnel because it was intended to support research on aircraft icing. The tunnel was built of wood, lined with sheet steel, and heavily insulated on the outside. Refrigeration equipment was installed to generate icing conditions inside the test section. The NACA sent out a questionnaire to airline operators, asking them to detail the specific kinds of icing problems they encountered in flight. The replies became the basis for a comprehensive research program begun in 1938 when the tunnel commenced operation. Research quickly focused on the concept of using exhaust heat to prevent ice from forming on the wing's leading edge. This project was led by Lewis Rodert, who later would win the Collier Trophy for his work on deicing. By 1940, aircraft icing research had shifted to the new Ames Research Laboratory, and the Ice tunnel was refitted with screens and honeycomb. Researchers were trying to eliminate all turbulence in the test section. From TN 1283: 'The Langley two-dimensional low-turbulence pressure tunnel is a single-return closed-throat tunnel.... The tunnel is constructed of heavy steel plate so that the pressure of the air may be varied from approximately full vacuum to 10 atmospheres absolute, thereby giving a wide range of air densities. Reciprocating compressors with a capacity of 1200 cubic feet of free air per minute provide compressed air. Since the tunnel shell has a volume of about 83,000 cubic feet, a compression rate of approximately one atmosphere per hour is obtained. ... The test section is rectangular in shape, 3 feet wide, 7 1/2 feet high, and 7 1/2 feet long. ... The over-all size of the wind-tunnel shell is about 146 feet long and 58 feet wide with a maximum diameter of 26 feet. The test section and entrance and exit cones are surrounded by a 22-foot diameter section of the shell to provide a

  11. Two-Dimensional Low-Turbulence Tunnel

    NASA Technical Reports Server (NTRS)

    1938-01-01

    Construction of the wood frame for the Two-Dimensional Low-Turbulence Tunnel. The Two-Dimensional Low-Turbulence Tunnel was originally called the Refrigeration or 'Ice' tunnel because it was intended to support research on aircraft icing. The tunnel was built of wood, lined with sheet steel, and heavily insulated on the outside. Refrigeration equipment was installed to generate icing conditions inside the test section. The NACA sent out a questionnaire to airline operators, asking them to detail the specific kinds of icing problems they encountered in flight. The replies became the basis for a comprehensive research program begun in 1938 when the tunnel commenced operation. Research quickly focused on the concept of using exhaust heat to prevent ice from forming on the wing's leading edge. This project was led by Lewis Rodert, who later would win the Collier Trophy for his work on deicing. By 1940, aircraft icing research had shifted to the new Ames Research Laboratory, and the Ice tunnel was refitted with screens and honeycomb. Researchers were trying to eliminate all turbulence in the test section. From TN 1283: 'The Langley two-dimensional low-turbulence pressure tunnel is a single-return closed-throat tunnel.... The tunnel is constructed of heavy steel plate so that the pressure of the air may be varied from approximately full vacuum to 10 atmospheres absolute, thereby giving a wide range of air densities. Reciprocating compressors with a capacity of 1200 cubic feet of free air per minute provide compressed air. Since the tunnel shell has a volume of about 83,000 cubic feet, a compression rate of approximately one atmosphere per hour is obtained. ... The test section is rectangular in shape, 3 feet wide, 7 1/2 feet high, and 7 1/2 feet long. ... The over-all size of the wind-tunnel shell is about 146 feet long and 58 feet wide with a maximum diameter of 26 feet. The test section and entrance and exit cones are surrounded by a 22-foot diameter section of the

  12. Two-Dimensional Low-Turbulence Tunnel

    NASA Technical Reports Server (NTRS)

    1938-01-01

    Manometer for the Two-Dimensional Low-Turbulence Tunnel. The Two-Dimensional Low-Turbulence Tunnel was originally called the Refrigeration or 'Ice' tunnel because it was intended to support research on aircraft icing. The tunnel was built of wood, lined with sheet steel, and heavily insulated on the outside. Refrigeration equipment was installed to generate icing conditions inside the test section. The NACA sent out a questionnaire to airline operators, asking them to detail the specific kinds of icing problems they encountered in flight. The replies became the basis for a comprehensive research program begun in 1938 when the tunnel commenced operation. Research quickly focused on the concept of using exhaust heat to prevent ice from forming on the wing's leading edge. This project was led by Lewis Rodert, who later would win the Collier Trophy for his work on deicing. By 1940, aircraft icing research had shifted to the new Ames Research Laboratory, and the Ice tunnel was refitted with screens and honeycomb. Researchers were trying to eliminate all turbulence in the test section. From TN 1283: 'The Langley two-dimensional low-turbulence pressure tunnel is a single-return closed-throat tunnel.... The tunnel is constructed of heavy steel plate so that the pressure of the air may be varied from approximately full vacuum to 10 atmospheres absolute, thereby giving a wide range of air densities. Reciprocating compressors with a capacity of 1200 cubic feet of free air per minute provide compressed air. Since the tunnel shell has a volume of about 83,000 cubic feet, a compression rate of approximately one atmosphere per hour is obtained. ... The test section is rectangular in shape, 3 feet wide, 7 1/2 feet high, and 7 1/2 feet long. ... The over-all size of the wind-tunnel shell is about 146 feet long and 58 feet wide with a maximum diameter of 26 feet. The test section and entrance and exit cones are surrounded by a 22-foot diameter section of the shell to provide a space

  13. 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

  14. 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.

  15. 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.

  16. Air pollution measurements in traffic tunnels.

    PubMed

    De Fré, R; Bruynseraede, P; Kretzschmar, J G

    1994-10-01

    Air pollution measurements during April 1991 are reported from the Craeybeckx highway tunnel in Antwerp, Belgium. The tunnel was used daily by an average of 45,000 vehicles, of which 60% were gasoline fueled passenger cars, 20% diesel cars, and 20% trucks. Of the gasoline cars, only 3% had three-way catalysts. Tunnel air concentrations of nitrogen oxides, sulphur dioxide, carbon dioxide, carbon monoxide, nonmethane hydrocarbons, volatile organic compounds, polycyclic aromatic hydrocarbons, and lead are presented. The traffic emissions in the tunnel are calculated by the carbon balance method, which uses the increase of the total carbon concentration in the tunnel air as the reference quantity. Division of the concentration of any pollutant by the total carbon concentration gives emission factors per kilogram of carbon. These emission factors can be converted directly to emissions relative to fuel consumption or per kilometer. The fraction of diesel used in the tunnel was derived from sulphur to carbon ratios in tunnel air. A calculation procedure with breakdown of emission factors according to vehicle categories was used to estimate countrywide emissions. The estimated emissions were compared to results from the Flanders Emissions Inventory [Emissie Inventaris Vlaamse Regio (EIVR)] and calculated emissions according to the emission factors proposed by the European Commissions CORINAIR Working Group. For NOx there is excellent agreement. For carbon monoxide and hydrocarbons, the tunnel data produced higher emissions than the CORINAIR model would predict but lower than the official EIVR statistics. The estimated lead emissions from traffic are found to be 22 to 29% of the lead in gasoline.

  17. Gottingen Wind Tunnel for Testing Aircraft Models

    NASA Technical Reports Server (NTRS)

    Prandtl, L

    1920-01-01

    Given here is a brief description of the Gottingen Wind Tunnel for the testing of aircraft models, preceded by a history of its development. Included are a number of diagrams illustrating, among other things, a sectional elevation of the wind tunnel, the pressure regulator, the entrance cone and method of supporting a model for simple drag tests, a three-component balance, and a propeller testing device, all of which are discussed in the text.

  18. Aeroelastic instability stoppers for wind tunnel models

    NASA Technical Reports Server (NTRS)

    Doggett, R. V., Jr.; Ricketts, R. H. (Inventor)

    1981-01-01

    A mechanism for constraining models or sections thereof, was wind tunnel tested, deployed at the onset of aeroelastic instability, to forestall destructive vibrations in the model is described. The mechanism includes a pair of arms pivoted to the tunnel wall and straddling the model. Rollers on the ends of the arms contact the model, and are pulled together against the model by a spring stretched between the arms. An actuator mechanism swings the arms into place and back as desired.

  19. 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.

  20. 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.

  1. 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

  2. Hoosac tunnel geothermal heat source. Final report

    SciTech Connect

    Not Available

    1982-06-10

    The Hoosac Rail Tunnel has been analyzed as a central element in a district heating system for the City of North Adams. The tunnel has been viewed as a collector of the earth's geothermal heat and a seasonal heat storage facility with heat piped to the tunnel in summer from existing facilities at a distance. Heated fluid would be transported in winter from the tunnel to users who would boost the temperature with individual heat pumps. It was concluded the tunnel is a poor source of geothermal heat. The maximum extractable energy is only 2200 million BTU (20000 gallons of oil) at 58/sup 0/F. The tunnel is a poor heat storage facility. The rock conductivity is so high that 75% of the heat injected would escape into the mountain before it could be recaptured for use. A low temperature system, with individual heat pumps for temperature boost could be economically attractive if a low cost fuel (byproduct, solid waste, cogeneration) or a cost effective seasonal heat storage were available.

  3. 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.

  4. 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.

  5. 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.'

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Tunnel boring waste test plan

    SciTech Connect

    Patricio, J.G. . Rockwell Hanford Operations)

    1984-03-01

    The test plan has been prepared in anticipation of the need to excavate certain repository openings by relying upon mechanical excavation techniques. The test plan proposes that specific technical issues can be resolved and key design parameters defined by excavating openings in basalt near the surface, utilizing a full face tunnel boring machine (TBM). The purpose and objective of this type of testing will define the overall feasibility and attributes of mechanical excavation in basalt. The test plan recognizes that although this technology is generally available for underground construction for some geologic settings, the current state of technology for excavation in basalt is limited and the potential for improvement is considerable. The test plan recommends that it is economically advantageous to conduct additional testing in the laboratory to allow refinement of this plan based on the laboratory results. Thus, this test plan is considered preliminary in nature, with respect to detailed testing recommendations. However, the gross design attributes and resource requirements of a near-surface TBM demonstration are considered to be valid. 15 refs., 7 figs., 3 tabs.

  12. 7 x 10-Foot Atmospheric Wind Tunnel (AWT)

    NASA Technical Reports Server (NTRS)

    1934-01-01

    Smoke generator for 7 x 10-Foot Atmospheric Wind Tunnel (AWT) (left center); Force Test Set-Up in the center. In 1928, the NACA decided to replace its original Atmospheric Wind Tunnel (AWT #1) with two tunnels--the 5-foot vertical tunnel and a 7 by 10 foot rectangular throat tunnel. Both were open-throat, closed-return-passage tunnels. While the 5-foot vertical tunnel was to be used mainly for spin tests, the 7x10 was an all-purpose tunnel although the main intent was to study stability and control problems. Construction was completed in the summer of 1930; calibration later that same year. The balance was installed and the tunnel went into operation in early 1931.

  13. Femoral tunnel malposition in ACL revision reconstruction.

    PubMed

    Morgan, Joseph A; Dahm, Diane; Levy, Bruce; Stuart, Michael J

    2012-11-01

    The Multicenter Anterior Cruciate Ligament (ACL) Revision Study (MARS) group was formed to study a large cohort of revision ACL reconstruction patients. The purpose of this subset analysis study of the MARS database is to describe specific details of femoral tunnel malposition and subsequent management strategies that surgeons chose in the revision setting. The design of this study is a case series. The multicenter MARS database is compiled from a questionnaire regarding 460 ACL reconstruction revision cases returned by 87 surgeons. This subset analysis described technical aspects and operative findings in specifically those cases in which femoral tunnel malposition was cited as the cause of primary ACL reconstruction failure. Of the 460 revisions included for study, 276 (60%) cases cited a specific "technical cause of failure." Femoral tunnel malposition was cited in 219 (47.6%) of 460 cases. Femoral tunnel malposition was cited as the only cause of failure in 117 cases (25.4%). Surgeons judged the femoral tunnel too vertical in 42 cases (35.9%), too anterior in 35 cases (29.9%), and too vertical and anterior in 31 cases (26.5%). Revision reconstruction involved the drilling of an entirely new femoral tunnel in 91 cases (82.1%). For primary reconstruction, autograft tissue was used in 82 cases (70.1%). For revision reconstruction, autograft tissue was used in 61 cases (52.1%) and allograft tissue in 56 cases (47.9%). Femoral tunnel malposition in primary ACL reconstruction was the most commonly cited reason for graft failure in this cohort. Graft selection is widely variable among surgeons.

  14. Femoral Tunnel Malposition in ACL Revision Reconstruction

    PubMed Central

    Morgan, Joseph A.; Dahm, Diane; Levy, Bruce; Stuart, Michael J.

    2013-01-01

    The Multicenter Anterior Cruciate Ligament (ACL) Revision Study (MARS) group was formed to study a large cohort of revision ACL reconstruction patients. The purpose of this subset analysis study of the MARS database is to describe specific details of femoral tunnel malposition and subsequent management strategies that surgeons chose in the revision setting. The design of this study is a case series. The multicenter MARS database is compiled from a questionnaire regarding 460 ACL reconstruction revision cases returned by 87 surgeons. This subset analysis described technical aspects and operative findings in specifically those cases in which femoral tunnel malposition was cited as the cause of primary ACL reconstruction failure. Of the 460 revisions included for study, 276 (60%) cases cited a specific “technical cause of failure.” Femoral tunnel malposition was cited in 219 (47.6%) of 460 cases. Femoral tunnel malposition was cited as the only cause of failure in 117 cases (25.4%). Surgeons judged the femoral tunnel too vertical in 42 cases (35.9%), too anterior in 35 cases (29.9%), and too vertical and anterior in 31 cases (26.5%). Revision reconstruction involved the drilling of an entirely new femoral tunnel in 91 cases (82.1%). For primary reconstruction, autograft tissue was used in 82 cases (70.1%). For revision reconstruction, autograft tissue was used in 61 cases (52.1%) and allograft tissue in 56 cases (47.9%). Femoral tunnel malposition in primary ACL reconstruction was the most commonly cited reason for graft failure in this cohort. Graft selection is widely variable among surgeons. PMID:23150344

  15. Carpal tunnel syndrome in children.

    PubMed

    Van Meir, Nathalie; De Smet, Luc

    2003-10-01

    Carpal tunnel syndrome (CTS) is rarely seen in children. A literature search in 1989 revealed 52 published cases. The authors review 163 additional cases that were published since that date. The majority of these cases were related with a genetic condition. The most common aetiology was lysosomal storage disease: mucopolysaccharidoses (MPS) in 95 and mucolipidoses (ML) in 22. In CTS secondary to MPS, clinical signs typical of adult CTS are rarely seen, and difficulty with fine motor tasks is the most frequent finding. CTS in MPS does not seem to be prevented by bone marrow transplantation, the usual treatment for the condition. CTS is probably due to a combination of excessive lysosomal storage in the connective tissue of the flexor retinaculum and a distorted anatomy because of underlying bone dysplasia. Mucolipidoses come next in the aetiology, with essentially similar symptoms. The authors found in the literature 11 cases of primary familial CTS, a condition which presents as an inheritable disorder of connective tissue mediated by an autosomal dominant gene; the symptoms may be more typical in some cases, but are more similar to MPS in others. A case with self-mutilation has been reported. Hereditary neuropathy with liability to pressure palsies (HNPP) is a rare autosomal dominant condition characterised by episodes of decreased sensation or palsies after slight traction or pressure on peripheral nerves; it may also give symptoms of CTS. Schwartz-Jampel syndrome (SJS), another genetic disorder with autosomal recessive skeletal dysplasia, is characterised by varying degrees of myotonia and chondrodysplasia; it has also been noted associated with CTS in a child. Melorrheostosis and Leri's syndrome have also been noted in children with CTS, as well as Déjerine-Sottas syndrome and Weill-Marchesani syndrome. Among non-genetic causes of CTS in children, idiopathic cases with children onset have been reported, usually but not always related with thickening of the

  16. Le LHC, un tunnel cosmique

    SciTech Connect

    2009-09-17

    Et si la lumière au bout du tunnel du LHC était cosmique ? En d’autres termes, qu’est-ce que le LHC peut nous apporter dans la connaissance de l’Univers ? Car la montée en énergie des accélérateurs de particules nous permet de mieux appréhender l’univers primordial, chaud et dense. Mais dans quel sens dit-on que le LHC reproduit des conditions proches du Big bang ? Quelles informations nous apporte-t-il sur le contenu de l’Univers ? La matière noire est-elle détectable au LHC ? L’énergie noire ? Pourquoi l’antimatière accumulée au CERN est-elle si rare dans l’Univers ? Et si le CERN a bâti sa réputation sur l’exploration des forces faibles et fortes qui opèrent au sein des atomes et de leurs noyaux, est-ce que le LHC peut nous apporter des informations sur la force gravitationnelle qui gouverne l’évolution cosmique ? Depuis une trentaine d’années, notre compréhension de l’univers dans ses plus grandes dimensions et l’appréhension de son comportement aux plus petites distances sont intimement liées : en quoi le LHC va-t-il tester expérimentalement cette vision unifiée ? Tout public, entrée libre / Réservations au +41 (0)22 767 76 76

  17. Tunneling behavior of ultracold atoms in optical traps

    NASA Astrophysics Data System (ADS)

    Wang, Binglu; Ma, Yanhua; Shen, Man; Li, Hong

    2016-07-01

    We investigate the tunneling of ultracold atoms in optical traps by using the path-integral method. We obtain the decay rate for tunneling out of a single-well and discuss how the rate is affected by the level splitting caused by the presence of a second adjacent well. Our calculations show that the transition through the potential barrier can be divided into three regions: the quantum tunneling region, the thermally assisted region and the thermal activation region. The tunneling process is found to be a second-order transition. We also show that level splitting due to tunneling can increase the tunneling rate.

  18. Computational Simulation of Semispan Wings in Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Olsen, Mike; Rizk, Yehia

    1998-01-01

    The computational modelling of experiments, with the end aim of providing sufficiently accurate simulations to assess and improve turbulence models is described. Solid wall tunnels are the only tunnels in which the boundary conditions can, in principle, be known exactly. The modelling of the tunnel walls for transonic flows requires the accurate modelling of the viscous displacement effects on the tunnel walls. This paper describes the modelling of semispan wing experiments in solid wall tunnels, with the tunnel walls modelled as inviscid walls, and with all 4 walls modelled viscously. The effect of the viscous effects is discussed, as well as the feasibility of modelling these effects in an inviscid, apriori manner.

  19. Vibration testing of the JE-M-604-4-IUE rocket motor (Thiokol P/N E 28639-03)

    NASA Technical Reports Server (NTRS)

    Alt, R. E.; Tosh, J. T.

    1976-01-01

    The NASA International Ultraviolet Explorer (IUE) rocket motor (TE-M-604-4), a solid fuel, spherical rocket motor, was vibration tested in the Impact, Vibration, and Acceleration (IVA) Test Unit of the von Karman Gas Dynamics Facility (VKF). The objective of the test program was to subject the motor to qualification levels of sinusoidal and random vibration prior to the altitude firing of the motor in the Propulsion Development Test Cell (T-3), Engine Test Facility (ETF), AEDC. The vibration testing consisted of a low level sine survey from 5 to 2,000 Hz, followed by a qualification level sine sweep and qualification level random vibration. A second low level sine survey followed the qualification level testing. This sequence of testing was accomplished in each of three orthogonal axes. No motor problems were observed due to the imposition of these dynamic environments.

  20. Channel selective tunnelling through a nanographene assembly.

    PubMed

    Wong, H S; Feng, X; Müllen, K; Chandrasekhar, N; Durkan, C

    2012-03-01

    We report selective tunnelling through a nanographene intermolecular tunnel junction achieved via scanning tunnelling microscope tip functionalization with hexa-peri-hexabenzocoronene (HBC) molecules. This leads to an offset in the alignment between the energy levels of the tip and the molecular assembly, resulting in the imaging of a variety of distinct charge density patterns in the HBC assembly, not attainable using a bare metallic tip. Different tunnelling channels can be selected by the application of an electric field in the tunnelling junction, which changes the condition of the HBC on the tip. Density functional theory-based calculations relate the imaged HBC patterns to the calculated molecular orbitals at certain energy levels. These patterns bear a close resemblance to the π-orbital states of the HBC molecule calculated at the relevant energy levels, mainly below the Fermi energy of HBC. This correlation demonstrates the ability of an HBC functionalized tip as regards accessing an energy range that is restricted to the usual operating bias range around the Fermi energy with a normal metallic tip at room temperature. Apart from relating to molecular orbitals, some patterns could also be described in association with the Clar aromatic sextet formula. Our observations may help pave the way towards the possibility of controlling charge transport between organic interfaces.

  1. Tunnel Ventilation Control Using Reinforcement Learning Methodology

    NASA Astrophysics Data System (ADS)

    Chu, Baeksuk; Kim, Dongnam; Hong, Daehie; Park, Jooyoung; Chung, Jin Taek; Kim, Tae-Hyung

    The main purpose of tunnel ventilation system is to maintain CO pollutant concentration and VI (visibility index) under an adequate level to provide drivers with comfortable and safe driving environment. Moreover, it is necessary to minimize power consumption used to operate ventilation system. To achieve the objectives, the control algorithm used in this research is reinforcement learning (RL) method. RL is a goal-directed learning of a mapping from situations to actions without relying on exemplary supervision or complete models of the environment. The goal of RL is to maximize a reward which is an evaluative feedback from the environment. In the process of constructing the reward of the tunnel ventilation system, two objectives listed above are included, that is, maintaining an adequate level of pollutants and minimizing power consumption. RL algorithm based on actor-critic architecture and gradient-following algorithm is adopted to the tunnel ventilation system. The simulations results performed with real data collected from existing tunnel ventilation system and real experimental verification are provided in this paper. It is confirmed that with the suggested controller, the pollutant level inside the tunnel was well maintained under allowable limit and the performance of energy consumption was improved compared to conventional control scheme.

  2. MR imaging in tarsal tunnel syndrome.

    PubMed

    Kerr, R; Frey, C

    1991-01-01

    Magnetic resonance imaging was used to demonstrate the normal anatomy of the tarsal tunnel in two volunteers and to evaluate 33 feet in 27 patients with tarsal tunnel syndrome. The tarsal tunnel is a fibroosseous channel extending from the ankle to the midfoot, through which the medial tendons and the posterior tibial neurovascular bundle pass. Tarsal tunnel syndrome is a compression neuropathy of the posterior tibial nerve or one of its branches and may be caused by a variety of pathologic lesions. Magnetic resonance imaging demonstrated a mass lesion in five feet, dilated veins or varicosities in eight feet, fracture or soft tissue injury in five feet, fibrous scar in two feet, flexor hallucis longus tenosynovitis in six feet, and abductor hallucis muscle hypertrophy in one foot. Six feet were normal on MR imaging. The findings of MR imaging were confirmed in 17 of 19 patients that went to surgery. Magnetic resonance is useful for localizing lesions within the tarsal tunnel and for determining the lesion extent and relationship to the posterior tibial nerve and its branches.

  3. Study of the shadow effect caused by a railway tunnel

    NASA Astrophysics Data System (ADS)

    Jin, Qiyun; Thompson, David

    2016-09-01

    When a train runs in a tunnel the largest vibration on the ground surface may not occur directly above the tunnel but at some lateral distance away from the tunnel alignment. This has been called the ‘shadow effect’. The characteristics of this shadow effect can help in understanding the distribution of vibration on the ground surface. For the current study it is first shown, using an analytical ground model, that a shadow region may occur for a force at some depth in the ground even in the absence of a tunnel; the extent of this effect depends on the Poisson's ratio of the soil. To introduce the tunnel a 2.5D finite element/boundary element model has been used to represent the coupled tunnel-ground situation. When the tunnel is present the vibration caused by excitation at the tunnel base shares many of the features found in the absence of the tunnel. However, the existence of the tunnel structure also influences these features, especially at high frequencies. It is found that, rather than the tunnel structure shielding the vibration from reaching the ground surface, its dominant effect is to transmit vibration from the tunnel base to the crown at high frequencies. The dependence of these effects on various parameters is studied, in particular the tunnel diameter, wall thickness and depth.

  4. 7 x 10 Foot Atmospheric Wind Tunnel (AWT)

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction of 7 x 10 Foot Atmospheric Wind Tunnel (AWT). In 1928, the NACA decided to replace its original Atmospheric Wind Tunnel (AWT #1) with two tunnels--the 5-foot vertical tunnel and a 7 by 10 foot rectangular throat tunnel. Both were open-throat, closed-return-passage tunnels. While the 5 foot vertical tunnel was to be used mainly for spin tests, the 7x10 was an all-purpose tunnel although the main intent was to study stability and control problems. Construction was completed in the summer of 1930; calibration later that same year. The balance was installed and the tunnel went into operation in early 1931. The Warwick Machine Co. of Newport News, Virginia had the contract to fabricate and erection the 7x10 Foot tunnel for a total cost of $18,018.90. The balance was made by Fairbanks, Morse and Co., of Baltimore, Maryland for $2,544.00. The honeycomb was made by the Berkley Machine Works and Foundry Co., Inc. of Norfolk, Virginia for $1,580 and the control panel by Clark Controller Co. of Cleveland, OH for $1,153. Published in NACA TR No. 412, 'The 7 by 10 Foot Wind Tunnel of the National Advisory Committee for Aeronautics,' by Thomas A. Harris, 1932; Reference Notes on the 'Atmospheric Wind Tunnel' in the Langley Historical Archives (D. Baals notes on wind tunnels).

  5. Electronic thermometry in tunable tunnel junction

    DOEpatents

    Maksymovych, Petro

    2016-03-15

    A tunable tunnel junction thermometry circuit includes a variable width tunnel junction between a test object and a probe. The junction width is varied and a change in thermovoltage across the junction with respect to the change in distance across the junction is determined. Also, a change in biased current with respect to a change in distance across the junction is determined. A temperature gradient across the junction is determined based on a mathematical relationship between the temperature gradient, the change in thermovoltage with respect to distance and the change in biased current with respect to distance. Thermovoltage may be measured by nullifying a thermoelectric tunneling current with an applied voltage supply level. A piezoelectric actuator may modulate the probe, and thus the junction width, to vary thermovoltage and biased current across the junction. Lock-in amplifiers measure the derivatives of the thermovoltage and biased current modulated by varying junction width.

  6. A survey of cryogenic wind tunnels

    NASA Technical Reports Server (NTRS)

    Kilgore, R. A.; Dress, D. A.

    1985-01-01

    Following the development of the cryogenic wind tunnel at the NASA Langley Research Center in 1972, a large number of cryogenic wind-tunnel projects have been undertaken at various research establishments around the world. The purpose of this paper is to describe some of the more significant of these projects. Described in this paper are cryogenic wind-tunnel projects in China (CARDC), England (College of Aeronautics at Cranfield, RAE-Bedford, and University of Southampton), 'Europe' (Pilot European Transonic Windtunnel at NAL-Amsterdam, and the European Transonic Windtunnel proposed for DFVLR-Koeln), France (ONERA-CERT), Germany (DFVLR-Koeln, and DFVLR-Goettingen), Japan (NAL, University of Tsukuba, and National Defense Academy), Sweden (Rollab), and the United States (Douglas Aircraft Co., University of Illinois at Urbana-Champaign, and NASA-Langley).

  7. Methyl tunnelling in trihalogeno-trimethyl-benzenes

    NASA Astrophysics Data System (ADS)

    Meinnel, J.; Häusler, W.; Mani, M.; Tazi, M.; Nusimovici, M.; Sanquer, M.; Wyncke, B.; Heidemann, A.; Carlile, C. J.; Tomkinson, J.; Hennion, B.

    1992-06-01

    Results of inelastic neutron scattering (INS) from 1,3,5-trihalogeno-2,4,6-trimethyl-benzenes are reported for the chloro-, the bromo- and the iodo-case. For the whole family the spectra show numerous similarities, in the μeV as well as in the meV range. We observe three tunnelling lines of equal intensity corresponding to three crystallographically inequivalent methyl rotors. The observed librational peaks are at much lower energies than expected from a pure threefold potential. Within the halogen family a systematic reduction of the barrier height is found with larger halogen sizes. The temperature dependence of the tunnelling energies shows the most pronounced difference between TBM and TIM, where the corresponding tunnelling lines even shift in opposite directions.

  8. Space Shuttle wind tunnel testing program

    NASA Technical Reports Server (NTRS)

    Whitnah, A. M.; Hillje, E. R.

    1984-01-01

    A major phase of the Space Shuttle Vehicle (SSV) Development Program was the acquisition of data through the space shuttle wind tunnel testing program. It became obvious that the large number of configuration/environment combinations would necessitate an extremely large wind tunnel testing program. To make the most efficient use of available test facilities and to assist the prime contractor for orbiter design and space shuttle vehicle integration, a unique management plan was devised for the design and development phase. The space shuttle program is reviewed together with the evolutional development of the shuttle configuration. The wind tunnel testing rationale and the associated test program management plan and its overall results is reviewed. Information is given for the various facilities and models used within this program. A unique posttest documentation procedure and a summary of the types of test per disciplines, per facility, and per model are presented with detailed listing of the posttest documentation.

  9. Isotope effects of hydrogen and atom tunnelling

    NASA Astrophysics Data System (ADS)

    Buchachenko, A. L.; Pliss, E. M.

    2016-06-01

    The abnormally high mass-dependent isotope effects in liquid-phase hydrogen (deuterium) atom transfer reactions, which are customarily regarded as quantum effects, are actually the products of two classical effects, namely, kinetic and thermodynamic ones. The former is determined by the rate constants for atom transfer and the latter is caused by nonbonded (or noncovalent) isotope effects in the solvation of protiated and deuterated reacting molecules. This product can mimic the large isotope effects that are usually attributed to tunnelling. In enzymatic reactions, tunnelling is of particular interest; its existence characterizes an enzyme as a rigid molecular machine in which the residence time of reactants on the reaction coordinate exceeds the waiting time for the tunnelling event. The magnitude of isotope effect becomes a characteristic parameter of the internal dynamics of the enzyme catalytic site. The bibliography includes 61 references.

  10. Strong-Field Tunneling without Ionization

    SciTech Connect

    Nubbemeyer, T.; Gorling, K.; Saenz, A.; Eichmann, U.; Sandner, W.

    2008-12-05

    In the tunneling regime of strong laser field ionization we measure a substantial fraction of neutral atoms surviving the laser pulse in excited states. The measured excited neutral atom yield extends over several orders of magnitude as a function of laser intensity. Our findings are compatible with the strong-field tunneling-plus-rescattering model, confirming the existence of a widely unexplored neutral exit channel (frustrated tunneling ionization). Strong experimental support for this mechanism as origin of excited neutral atoms stems from the dependence of the excited neutral yield on the laser ellipticity, which is as expected for a rescattering process. Theoretical support for the proposed mechanism comes from the agreement of the neutral excited state distribution centered at n=6-10 obtained from both, a full quantum mechanical and a semiclassical calculation, in agreement with the experimental results.

  11. Research on self-correcting wind tunnels

    NASA Technical Reports Server (NTRS)

    Vidal, R. J.; Erickson, J. C., Jr.

    1978-01-01

    The Calspan self-correcting wind tunnel is a two-dimensional facility in which the flow field in the vicinity of the walls is actively controlled, and a theoretical evaluation is used in conjunction with flow field measurements to confirm that wall interference was minimized. The facility is described, and the results of experiments with a 6 percent-blockage model are presented to show that iterative application of wall control effectively eliminates the interference. Experiments were performed at conditions where the flow at the walls was supercritical, and a new operating procedure is described for these conditions. The results of an analysis of the flow in the auxiliary suction system and test ion illustrate the tradeoffs available in the design of self-correcting wind tunnel test sections and in model sizing for such tunnels.

  12. Nonadiabatic Tunneling in Photodissociation of Phenol.

    PubMed

    Xie, Changjian; Ma, Jianyi; Zhu, Xiaolei; Yarkony, David R; Xie, Daiqian; Guo, Hua

    2016-06-29

    Using recently developed full-dimensional coupled quasi-diabatic ab initio potential energy surfaces including four electronic ((1)ππ, (1)ππ*, 1(1)πσ*, and 2(1)πσ*) states, the tunneling dynamics of phenol photodissociation via its first excited singlet state (S1 ← S0) is investigated quantum mechanically using a three-dimensional model. The lifetimes of several low-lying vibrational states are examined and compared with experiment. The deuteration of the phenoxyl hydrogen is found to dramatically increase the lifetime, attesting to the tunneling nature of the nonadiabatic dissociation. Importantly, it is shown that owing to the conical intersection topography tunneling in this system cannot be described in the standard adiabatic approximation, which eschews the geometric phase effect since the nonadiabatically computed lifetimes, validated by comparison with experiment, differ significantly from those obtained in that limit.

  13. Effects of vibrational excitation on multidimensional tunneling: General study and proton tunneling in tropolone

    NASA Astrophysics Data System (ADS)

    Takada, Shoji; Nakamura, Hiroki

    1995-03-01

    Tunneling energy splittings of vibrationally excited states are calculated quantum mechanically using several models of two-dimensional symmetric double well potentials. Various effects of vibrational excitation on tunneling are found to appear, depending on the topography of potential energy surface; the symmetry of the mode coupling plays an essential role. Especially, oscillation of tunneling splitting with respect to vibrational quantum number can occur and is interpreted by a clear physical picture based on the semiclassical theory formulated recently [Takada and Nakamura, J. Chem. Phys. 100, 98 (1994)]. The mixed tunneling in the C region found there allows the wave functions to have nodal lines in classically inaccessible region and can cause the suppression of the tunneling. The above analysis is followed by the interpretation of recent experiments of proton tunneling in tropolone. Ab initio molecular orbital calculations are carried out for the electronically ground state. A simple three-dimensional model potential is constructed and employed to analyze the proton tunneling dynamics. Some of the experimentally observed intriguing features can be explained by the typical mechanisms discussed above.

  14. Le LHC, un tunnel cosmique

    ScienceCinema

    None

    2016-07-12

    Et si la lumière au bout du tunnel du LHC était cosmique ? En d’autres termes, qu’est-ce que le LHC peut nous apporter dans la connaissance de l’Univers ? Car la montée en énergie des accélérateurs de particules nous permet de mieux appréhender l’univers primordial, chaud et dense. Mais dans quel sens dit-on que le LHC reproduit des conditions proches du Big bang ? Quelles informations nous apporte-t-il sur le contenu de l’Univers ? La matière noire est-elle détectable au LHC ? L’énergie noire ? Pourquoi l’antimatière accumulée au CERN est-elle si rare dans l’Univers ? Et si le CERN a bâti sa réputation sur l’exploration des forces faibles et fortes qui opèrent au sein des atomes et de leurs noyaux, est-ce que le LHC peut nous apporter des informations sur la force gravitationnelle qui gouverne l’évolution cosmique ? Depuis une trentaine d’années, notre compréhension de l’univers dans ses plus grandes dimensions et l’appréhension de son comportement aux plus petites distances sont intimement liées : en quoi le LHC va-t-il tester expérimentalement cette vision unifiée ? Tout public, entrée libre / Réservations au +41 (0)22 767 76 76

  15. Ultrafast Nonlinear Optics in the Tunneling Junction

    NASA Astrophysics Data System (ADS)

    Yarotski, Dmitry

    2014-03-01

    Coupling of the electromagnetic radiation to the tip-sample junction of a scanning tunneling microscope (STM) offers exciting opportunities in molecular adsorbate identification, high-resolution dopant profiling, studies of the molecular motion and detection of dynamic changes in the electronic structure of the materials. Microwave spectral region is of particular interest because it encompasses rotational, magnetic and other resonances of molecular and solid state systems. However, previous works have either used external microwave sources or generated microwave radiation by a nonlinear mixing of the outputs from two continuous-wave lasers in a tunneling junction. In both cases, the usable spectrum was limited to a single or few frequencies. On the other hand, the regular train of pulses from a mode-locked ultrafast laser has a spectrum which represents an optical frequency comb, with a series of narrow lines (modes) spaced by the pulse repetition frequency. Here, we will show that the nonlinear response of the tunneling junction of an STM to the field of ultrashort laser pulses results in an intermode mixing that produces microwave frequency comb (MFC) with harmonics up to n = 200 (14.85 GHz) on both semiconducting and metallic surfaces. The observed dependence of the microwave power on the harmonic number reveals adverse effects of the tunneling gap capacitance but also shows that the roll-off at higher microwave frequencies should be negligible within the tunneling junction itself leading to intrinsic MFC spread up to THz region. We also demonstrate that MFC generation on semiconductor surface might have the same origin as THz generation in a surface depletion field. Generation of the broadband microwave signals within the tunneling junction should reduce the extraneous effects and provide significantly higher coupling efficiency. With improved frequency response, the described MFC-STM may find broad range of applications in nanoscale characterization of

  16. View of Pressure Tunnel Intake at Stehr Lake. Looking southeast ...

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

    View of Pressure Tunnel Intake at Stehr Lake. Looking southeast - Childs-Irving Hydroelectric Project, Childs System, Pressure Tunnel Intake, Forest Service Road 708/502, Camp Verde, Yavapai County, AZ

  17. 5. VIEW OF TUNNEL OUTLET AND CHANNEL, LOOKING SOUTH ...

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

    5. VIEW OF TUNNEL OUTLET AND CHANNEL, LOOKING SOUTH - High Mountain Dams in Upalco Unit, Farmers Lake Tunnel, Ashley National Forest, 5.7 miles North of Swift Creek Campground, Mountain Home, Duchesne County, UT

  18. 12. VIEW EAST, BUILDING 12 INTERIOR, WIND TUNNEL 157 ...

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

    12. VIEW EAST, BUILDING 12 INTERIOR, WIND TUNNEL 157 - Naval Surface Warfare Center, Transonic Wind Tunnel Building, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  19. 4. VIEW NORTHWEST OF SUPERSONIC WIND TUNNEL BUILDING TO TRANSONIC ...

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

    4. VIEW NORTHWEST OF SUPERSONIC WIND TUNNEL BUILDING TO TRANSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  20. 6. VIEW OF FIVEFOOT WIND TUNNEL WITH AIR STRAIGHTENER AND ...

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

    6. VIEW OF FIVE-FOOT WIND TUNNEL WITH AIR STRAIGHTENER AND OPERATOR STATION IN FOREGROUND (1991). - Wright-Patterson Air Force Base, Area B, Building No. 19, Five-Foot Wind Tunnel, Dayton, Montgomery County, OH

  1. 1. VIEW SOUTHWEST OF SUBSONIC WIND TUNNEL BUILDING AND TRANSONIC ...

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

    1. VIEW SOUTHWEST OF SUBSONIC WIND TUNNEL BUILDING AND TRANSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  2. 5. VIEW NORTHWEST OF SUBSONIC WIND TUNNEL BUILDING TO TRANSONIC ...

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

    5. VIEW NORTHWEST OF SUBSONIC WIND TUNNEL BUILDING TO TRANSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  3. 2. VIEW SOUTH OF WIND TUNNEL 157, NORTH ELEVATION ...

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

    2. VIEW SOUTH OF WIND TUNNEL 157, NORTH ELEVATION - Naval Surface Warfare Center, Transonic Wind Tunnel Building, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  4. 3. VIEW SOUTHEAST OF TRANSONIC WIND TUNNEL BUILDING TO SUBSONIC ...

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

    3. VIEW SOUTHEAST OF TRANSONIC WIND TUNNEL BUILDING TO SUBSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  5. 7. VIEW WEST OF SCALE ROOM IN FULLSCALE WIND TUNNEL; ...

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

    7. VIEW WEST OF SCALE ROOM IN FULL-SCALE WIND TUNNEL; SCALES ARE USED TO MEASURE FORCES ACTING ON MODEL AIRCRAFT SUSPENDED ABOVE. - NASA Langley Research Center, Full-Scale Wind Tunnel, 224 Hunting Avenue, Hampton, Hampton, VA

  6. 2. VIEW SOUTH OF TRANSONIC WIND TUNNEL BUILDING AND SUPERSONIC ...

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

    2. VIEW SOUTH OF TRANSONIC WIND TUNNEL BUILDING AND SUPERSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  7. 7. VIEW NORTHWEST OF SUBSONIC WIND TUNNEL BUILDING TO TRANSONIC ...

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

    7. VIEW NORTHWEST OF SUBSONIC WIND TUNNEL BUILDING TO TRANSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  8. 2. VIEW SOUTH OF WIND TUNNEL 138 AND COOLING SYSTEM ...

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

    2. VIEW SOUTH OF WIND TUNNEL 138 AND COOLING SYSTEM 140, NORTH ELEVATION - Naval Surface Warfare Center, Subsonic Wind Tunnel Building, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  9. 8. VIEW SOUTHWEST, INTERIOR VIEW, WIND TUNNEL 139 Naval ...

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

    8. VIEW SOUTHWEST, INTERIOR VIEW, WIND TUNNEL 139 - Naval Surface Warfare Center, Subsonic Wind Tunnel Building, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  10. 13. VIEW NORTHEAST, BUILDING 12 INTERIOR, WIND TUNNEL FAN ASSEMBLY ...

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

    13. VIEW NORTHEAST, BUILDING 12 INTERIOR, WIND TUNNEL FAN ASSEMBLY - Naval Surface Warfare Center, Transonic Wind Tunnel Building, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  11. 23. CUESTA TUNNEL, PORTAL STRUCTURES. Leeds, Hill, Barnard & Jewett ...

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

    23. CUESTA TUNNEL, PORTAL STRUCTURES. Leeds, Hill, Barnard & Jewett drawing, no number, revised 10/10/41. - Salinas River Project, Cuesta Tunnel, Southeast of U.S. 101, San Luis Obispo, San Luis Obispo County, CA

  12. 4. INTERIOR OF ABANDONED SANTA ANA CANAL TUNNEL, SHOWING CEMENT ...

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

    4. INTERIOR OF ABANDONED SANTA ANA CANAL TUNNEL, SHOWING CEMENT TROUGH FLOOR AND UNFINISHED GRANITE ROOF. VIEW TO SOUTHWEST. - Santa Ana River Hydroelectric System, Abandoned Tunnel, Redlands, San Bernardino County, CA

  13. 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

  14. 30. ZIONMOUNT CARMEL HIGHWAY, PROPOSED TUNNEL ALIGNMENT. PHOTOGRAPH TAKEN FROM ...

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

    30. ZION-MOUNT CARMEL HIGHWAY, PROPOSED TUNNEL ALIGNMENT. PHOTOGRAPH TAKEN FROM NEAR CANYON OVERLOOK TRAIL. CLIFF BRAY, PHOTOGRAPHER, 1928. - Zion-Mount Carmel Highway, Tunnel, Two miles east of Zion Canyon Scenic Drive, Springdale, Washington County, UT

  15. El Tovar steam tunnel breaker box in foreground. Note El ...

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

    El Tovar steam tunnel breaker box in foreground. Note El Tovar stone vault in alignment with tunnel. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  16. 3. VIEW OF TUNNEL INTAKE, WITH LOG TRASH RACK, LOOKING ...

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

    3. VIEW OF TUNNEL INTAKE, WITH LOG TRASH RACK, LOOKING SOUTH - High Mountain Dams in Upalco Unit, Farmers Lake Tunnel, Ashley National Forest, 5.7 miles North of Swift Creek Campground, Mountain Home, Duchesne County, UT

  17. 39. TUNNEL BORE UNDER CONSTRUCTION. VIEW SHOWS LIGHT CONSTRUCTION RAILWAY ...

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

    39. TUNNEL BORE UNDER CONSTRUCTION. VIEW SHOWS LIGHT CONSTRUCTION RAILWAY FOR HAULING MUCK AND SPOIL - Zion-Mount Carmel Highway, Tunnel, Two miles east of Zion Canyon Scenic Drive, Springdale, Washington County, UT

  18. A Top Pilot Tunnel Preconditioning Method for the Prevention of Extremely Intense Rockbursts in Deep Tunnels Excavated by TBMs

    NASA Astrophysics Data System (ADS)

    Zhang, Chuanqing; Feng, Xiating; Zhou, Hui; Qiu, Shili; Wu, Wenping

    2012-05-01

    The headrace tunnels at the Jinping II Hydropower Station cross the Jinping Mountain with a maximum overburden depth of 2,525 m, where 80% of the strata along the tunnels consist of marble. A number of extremely intense rockbursts occurred during the excavation of the auxiliary tunnels and the drainage tunnel. In particular, a tunnel boring machine (TBM) was destroyed by an extremely intense rockburst in a 7.2-m-diameter drainage tunnel. Two of the four subsequent 12.4-m-diameter headrace tunnels will be excavated with larger size TBMs, where a high risk of extremely intense rockbursts exists. Herein, a top pilot tunnel preconditioning method is proposed to minimize this risk, in which a drilling and blasting method is first recommended for the top pilot tunnel excavation and support, and then the TBM excavation of the main tunnel is conducted. In order to evaluate the mechanical effectiveness of this method, numerical simulation analyses using the failure approaching index, energy release rate, and excess shear stress indices are carried out. Its construction feasibility is discussed as well. Moreover, a microseismic monitoring technique is used in the experimental tunnel section for the real-time monitoring of the microseismic activities of the rock mass in TBM excavation and for assessing the effect of the top pilot tunnel excavation in reducing the risk of rockbursts. This method is applied to two tunnel sections prone to extremely intense rockbursts and leads to a reduction in the risk of rockbursts in TBM excavation.

  19. Application Of Artificial Intelligence To Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Lo, Ching F.; Steinle, Frank W., Jr.

    1989-01-01

    Report discusses potential use of artificial-intelligence systems to manage wind-tunnel test facilities at Ames Research Center. One of goals of program to obtain experimental data of better quality and otherwise generally increase productivity of facilities. Another goal to increase efficiency and expertise of current personnel and to retain expertise of former personnel. Third goal to increase effectiveness of management through more efficient use of accumulated data. System used to improve schedules of operation and maintenance of tunnels and other equipment, assignment of personnel, distribution of electrical power, and analysis of costs and productivity. Several commercial artificial-intelligence computer programs discussed as possible candidates for use.

  20. Resonant tunneling in graphene pseudomagnetic quantum dots.

    PubMed

    Qi, Zenan; Bahamon, D A; Pereira, Vitor M; Park, Harold S; Campbell, D K; Neto, A H Castro

    2013-06-12

    Realistic relaxed configurations of triaxially strained graphene quantum dots are obtained from unbiased atomistic mechanical simulations. The local electronic structure and quantum transport characteristics of y-junctions based on such dots are studied, revealing that the quasi-uniform pseudomagnetic field induced by strain restricts transport to Landau level- and edge state-assisted resonant tunneling. Valley degeneracy is broken in the presence of an external field, allowing the selective filtering of the valley and chirality of the states assisting in the resonant tunneling. Asymmetric strain conditions can be explored to select the exit channel of the y-junction.

  1. Carpal tunnel release complicated by necrotizing fasciitis.

    PubMed

    Greco, R J; Curtsinger, L J

    1993-06-01

    We report a 31-year-old diabetic woman who underwent carpal tunnel release for median nerve compression followed by a laparoscopic tubal ligation. The procedure was complicated by a severe postoperative necrotizing fasciitis infection of the carpal tunnel release incision. This has not been previously reported. The wound was poorly responsive to antibiotic therapy and serial wound debridements. Control of the woman's infection required total excision of the palmar skin and fascia. Complicating factors in this case included the woman's long history of insulin-dependent diabetes and a concomitant clean-contaminated procedure.

  2. SIN tunnel junction as a temperature sensor

    NASA Astrophysics Data System (ADS)

    Golubev, D.; Kuzmin, Leonid S.; Willander, Magnus

    1999-04-01

    The current-voltage characteristics of a superconductor-normal metal tunnel junction (SIN) is very sensitive to the temperature of the normal metal. Therefore SIN junction can be used as a thermometer which can be conveniently integrated into more complicated devices, for example bolometers. We estimate the effect of different types of noise on the sensitivity of such a thermometer. Shot noise of the tunnel junction, amplifier noise and the noise related to the fluctuations of the heat flow through the junction are considered. The performance of the bolometer with SIN junction as a temperature sensor is also discussed.

  3. Treatment of repetitive use carpal tunnel syndrome

    NASA Astrophysics Data System (ADS)

    Smith, Chadwick F.; Vangsness, C. Thomas; Anderson, Thomas; Good, Wayne

    1995-05-01

    In 1990, a randomized, double-blind study was initiated to evaluate the use of an eight-point conservative treatment program in carpal tunnel syndrome. A total of 160 patients were delineated with symptoms of carpal tunnel syndrome. These patients were then divided into two groups. Both groups were subjected to an ergonomically correct eight-point work modification program. A counterfeit low level laser therapy unit was utilized in Group A, while an actual low level laser therapy unit was utilized in Group B. The difference between Groups A and B was statistically significant in terms of return to work, conduction study improvement, and certain range of motion and strength studies.

  4. Prevalence of carpal tunnel syndrome in motorcyclists.

    PubMed

    Manes, Harvey R

    2012-05-01

    Carpal tunnel syndrome is prevalent in patients who have a repetitive motion, vibration, or pressure exerted on the wrist joint for an extended period of time. The prevalence of this condition in the general population is approximately 5%. Motorcyclists subject themselves to high levels of vibration from the road and use their wrists to control the motorcycle's brakes, gas intake, and gears via the handlebars. Under these conditions, the author hypothesized that an increased prevalence of carpal tunnel syndrome would be observed in this population.

  5. Within-Tunnel Variations in Pressure Data for Three Transonic Wind Tunnels

    NASA Technical Reports Server (NTRS)

    DeLoach, Richard

    2014-01-01

    This paper compares the results of pressure measurements made on the same test article with the same test matrix in three transonic wind tunnels. A comparison is presented of the unexplained variance associated with polar replicates acquired in each tunnel. The impact of a significance component of systematic (not random) unexplained variance is reviewed, and the results of analyses of variance are presented to assess the degree of significant systematic error in these representative wind tunnel tests. Total uncertainty estimates are reported for 140 samples of pressure data, quantifying the effects of within-polar random errors and between-polar systematic bias errors.

  6. Spin-polarized tunneling in MgO-based tunnel junctions with superconducting electrodes

    NASA Astrophysics Data System (ADS)

    Schebaum, Oliver; Fabretti, Savio; Moodera, Jagadeesh S.; Thomas, Andy

    2012-03-01

    We prepared magnetic tunnel junctions with one ferromagnetic and one superconducting Al-Si electrode. Pure cobalt electrodes were compared with a Co-Fe-B alloy and the Heusler compound Co2FeAl. The polarization of the tunneling electrons was determined using the Maki-Fulde model and is discussed along with the spin-orbit scattering and the total pair-breaking parameters. The junctions were post-annealed at different temperatures to investigate the symmetry filtering mechanism responsible for the giant tunneling magnetoresistance ratios in Co-Fe-B/MgO/Co-Fe-B junctions.

  7. Site-directed deep electronic tunneling through a molecular network

    SciTech Connect

    Caspary, Maytal; Peskin, Uri

    2005-10-15

    Electronic tunneling in a complex molecular network of N(>2) donor/acceptor sites, connected by molecular bridges, is analyzed. The 'deep' tunneling dynamics is formulated using a recursive perturbation expansion, yielding a McConnell-type reduced N-level model Hamiltonian. Applications to models of molecular junctions demonstrate that the donor-bridge contact parameters can be tuned in order to control the tunneling dynamics and particularly to direct the tunneling pathway to either one of the various acceptors.

  8. View of east entrance to Flume Tunnel #2. In foreground, ...

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

    View of east entrance to Flume Tunnel #2. In foreground, covered decking (covered by debris) protects the flume below it (not visible). The extreme top of the tunnel entrance is visible in the middle of the picture, just beyond the covered decking. This is typical of gravity tunnel entrances and the only photograph representing these features in the system. Looking south - Childs-Irving Hydroelectric Project, Childs System, Flume Tunnel No. 2, Forest Service Road 708/502, Camp Verde, Yavapai County, AZ

  9. Fabrication of magnetic tunnel junctions with epitaxial and textured ferromagnetic layers

    DOEpatents

    Chang, Y. Austin; Yang, Jianhua Joshua

    2008-11-11

    This invention relates to magnetic tunnel junctions and methods for making the magnetic tunnel junctions. The magnetic tunnel junctions include a tunnel barrier oxide layer sandwiched between two ferromagnetic layers both of which are epitaxial or textured with respect to the underlying substrate upon which the magnetic tunnel junctions are grown. The magnetic tunnel junctions provide improved magnetic properties, sharper interfaces and few defects.

  10. 6. East portal of Tunnel 18, oblique view to northwest, ...

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

    6. East portal of Tunnel 18, oblique view to northwest, 135mm lens. This view shows to advantage the stepped ashlar granite wingwalls and fitted rubble slab slope protection flanking the portal, features typical of the Southern Pacific Common Standard tunnels. - Central Pacific Transcontinental Railroad, Tunnel No. 18, Milepost 120.5, Newcastle, Placer County, CA

  11. 6. East portal of Tunnel 17, oblique view to westsouthwest, ...

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

    6. East portal of Tunnel 17, oblique view to west-southwest, 90mm lens. This view shows to advantage the stepped concrete wingwalls and fitted stone masonry coping protection flanking the portal, features typical of the Southern Pacific Common Standard tunnels of this period. - Southern Pacific Railroad Natron Cutoff, Tunnel No. 17, Milepost 408, Dorris, Siskiyou County, CA

  12. Event tunnel: exploring event-driven business processes.

    PubMed

    Suntinger, Martin; Obweger, Hannes; Schiefer, Josef; Gröller, M Eduard

    2008-01-01

    Event-based systems monitor business processes in real time. The event-tunnel visualization sees the stream of events captured from such systems as a cylindrical tunnel. The tunnel allows for back-tracing business incidents and exploring event patterns' root causes. The authors couple this visualization with tools that let users search for relevant events within a data repository.

  13. 8. FIGUEROA STREET TUNNEL NO. 2, SOUTH PORTAL SEEN FROM ...

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

    8. FIGUEROA STREET TUNNEL NO. 2, SOUTH PORTAL SEEN FROM ABOVE NORTH PORTAL OF TUNNEL NO. 3. LOOKING 12°N. - Figueroa Street Tunnels, Mileposts 24.90, 25.14, 25.28, & 25.37 on Arroyo Seco Parkway, Los Angeles, Los Angeles County, CA

  14. 3. East portal of Tunnel 39, view to west with ...

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

    3. East portal of Tunnel 39, view to west with east portal of Tunnel 38 (HAER CA-211) visible in distance, 135mm lens with electronic flash fill. - Central Pacific Transcontinental Railroad, Tunnel No. 39, Milepost 180.95, Cisco, Placer County, CA

  15. 1. West portal of Tunnel 35, contextual view to eastnortheast ...

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

    1. West portal of Tunnel 35, contextual view to east-northeast with west portal of Tunnel 36 (HAER CA-209) visible in distance at left, 135mm lens. - Central Pacific Transcontinental Railroad, Tunnel No. 35, Milepost 176.62, Yuba Pass, Nevada County, CA

  16. 1. West portal of Tunnel 39, contextual view to east, ...

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

    1. West portal of Tunnel 39, contextual view to east, 135mm lens. West portal of Tunnel 4 (HAER CA-214) on the original Central Pacific Transcontinental line is visible at left. - Central Pacific Transcontinental Railroad, Tunnel No. 39, Milepost 180.95, Cisco, Placer County, CA

  17. 1. West portal of Tunnel 38, contextual view to east, ...

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

    1. West portal of Tunnel 38, contextual view to east, 135mm lens. West portal of Tunnel 3 (HAER CA-212) on original Central Pacific Transcontinental line visible in distance at left. - Central Pacific Transcontinental Railroad, Tunnel No. 38, Milepost 180.58, Cisco, Placer County, CA

  18. 5. East portal of Tunnel 41, contextual view to westnorthwest, ...

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

    5. East portal of Tunnel 41, contextual view to west-northwest, 135mm lens. Summit of Mount Judah, named for the visionary engineer who conceived and mapped the route of the first transcontinental railroad, rises above the tunnel. - Central Pacific Transcontinental Railroad, Tunnel No. 41, Milepost 193.3, Donner, Placer County, CA

  19. 3. East portal of Tunnel 25, contextual view to southwest ...

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

    3. East portal of Tunnel 25, contextual view to southwest from atop Tunnel 26 (HAER CA-202), with the original Central Pacific Transcontinental line passing above the new line, 135mm lens. - Central Pacific Transcontinental Railroad, Tunnel No. 25, Milepost 133.09, Applegate, Placer County, CA

  20. VIEW TO THE EAST, TOWARD TUNNEL EXTENSION AND REAR SIDE ...

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

    VIEW TO THE EAST, TOWARD TUNNEL EXTENSION AND REAR SIDE OF EAST PORTAL, FROM THE HILL THROUGH WHICH THE TUNNEL PASSES. 4 - Burlington Northern Santa Fe Railroad, Cajon Subdivision, Tunnel No. 2, Between Cajon Summit and Keenbrook, Devore, San Bernardino County, CA

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

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

    2. West portal of Tunnel 26, contextual view to northeast from track level, 135mm lens. Tunnel 27 (HAER CA-203) is visible in the distance. - Central Pacific Transcontinental Railroad, Tunnel No. 26, Milepost 133.29, Applegate, Placer County, CA

  2. Optical realization of two-boson tunneling dynamics

    SciTech Connect

    Longhi, Stefano

    2011-04-15

    An optical realization of the tunneling dynamics of two interacting bosons in a double-well potential, based on light transport in a four-core microstructured fiber, is proposed. The optical setting enables one to visualize, in a purely classical system, the entire crossover from Rabi oscillations to correlated pair tunneling and to tunneling of a fragmented pair in the fermionization limit.

  3. 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... Sites § 3832.41 What is a tunnel site? A tunnel site is a subsurface right-of-way under Federal land open to mineral entry. It is used for access to lode mining claims or to explore for blind...

  4. 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... Sites § 3832.41 What is a tunnel site? A tunnel site is a subsurface right-of-way under Federal land open to mineral entry. It is used for access to lode mining claims or to explore for blind...

  5. 4. East portal of Tunnel 17, contextual view to southeast, ...

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

    4. East portal of Tunnel 17, contextual view to southeast, 135mm lens. This end of the tunnel was badly damaged during construction in April 1909 by a disgruntled worker who set off a heavy powder charge, injuring fellow workers and destroying a steam shovel. - Southern Pacific Railroad Natron Cutoff, Tunnel No. 17, Milepost 408, Dorris, Siskiyou County, CA

  6. Particles' Tunneling in Spherically Symmetric Spacetimes with Dark Matter

    NASA Astrophysics Data System (ADS)

    Li, Guo-Ping; Zhou, Yun-Gang; Zu, Xiao-Tao

    2013-11-01

    Applying the Hamilton-Jacobi method, we investigate particles’ tunneling behavior in a spherically symmetric spacetime with dark matter. The tunneling rate and Hawking temperature at the event horizon are obtained. The result shows that the dark matter parameter β has an important influence on the Hawking temperature and the tunneling rate.

  7. View of Flume Tunnel #5 showing an example of concrete ...

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

    View of Flume Tunnel #5 showing an example of concrete flume covered with concrete slabs as it enters a tunnel under the road (FS 502). Looking southwest - Childs-Irving Hydroelectric Project, Childs System, Flume Tunnel No. 5, Forest Service Road 708/502, Camp Verde, Yavapai County, AZ

  8. Silicon-germanium nanowire tunnel-FETs with homo- and heterostructure tunnel junctions

    NASA Astrophysics Data System (ADS)

    Richter, S.; Blaeser, S.; Knoll, L.; Trellenkamp, S.; Fox, A.; Schäfer, A.; Hartmann, J. M.; Zhao, Q. T.; Mantl, S.

    2014-08-01

    Experimental results on tunneling field-effect transistors (TFETs) based on strained SiGe on SOI nanowire arrays are presented. A heterostructure SiGe/Si TFET with a vertical tunnel junction consisting of an in situ doped SiGe source and a Si channel with a minimum inverse subthreshold slope of 90 mV/dec is demonstrated. An increase in tunneling area results in higher on-current. The in situ doped heterojunction TFET shows great improvement compared to a homojunction SiGe on SOI nanowire design with implanted junctions. Temperature dependent measurements and device simulations are performed in order to analyze the tunnel transport mechanism in the devices.

  9. Anomalous Tunnel Magnetoresistance and Spin Transfer Torque in Magnetic Tunnel Junctions with Embedded Nanoparticles

    PubMed Central

    Useinov, Arthur; Ye, Lin-Xiu; Useinov, Niazbeck; Wu, Te-Ho; Lai, Chih-Huang

    2015-01-01

    The tunnel magnetoresistance (TMR) in the magnetic tunnel junction (MTJ) with embedded nanoparticles (NPs) was calculated in range of the quantum-ballistic model. The simulation was performed for electron tunneling through the insulating layer with embedded magnetic and non-magnetic NPs within the approach of the double barrier subsystem connected in parallel to the single barrier one. This model can be applied for both MTJs with in-plane magnetization and perpendicular one. We also calculated the in-plane component of the spin transfer torque (STT) versus the applied voltage in MTJs with magnetic NPs and determined that its value can be much larger than in single barrier system (SBS) for the same tunneling thickness. The reported simulation reproduces experimental data of the TMR suppression and peak-like TMR anomalies at low voltages available in leterature. PMID:26681336

  10. Anomalous Tunnel Magnetoresistance and Spin Transfer Torque in Magnetic Tunnel Junctions with Embedded Nanoparticles

    NASA Astrophysics Data System (ADS)

    Useinov, Arthur; Ye, Lin-Xiu; Useinov, Niazbeck; Wu, Te-Ho; Lai, Chih-Huang

    2015-12-01

    The tunnel magnetoresistance (TMR) in the magnetic tunnel junction (MTJ) with embedded nanoparticles (NPs) was calculated in range of the quantum-ballistic model. The simulation was performed for electron tunneling through the insulating layer with embedded magnetic and non-magnetic NPs within the approach of the double barrier subsystem connected in parallel to the single barrier one. This model can be applied for both MTJs with in-plane magnetization and perpendicular one. We also calculated the in-plane component of the spin transfer torque (STT) versus the applied voltage in MTJs with magnetic NPs and determined that its value can be much larger than in single barrier system (SBS) for the same tunneling thickness. The reported simulation reproduces experimental data of the TMR suppression and peak-like TMR anomalies at low voltages available in leterature.

  11. A combustion driven shock tunnel to complement the free piston shock tunnel T5 at GALCIT

    NASA Technical Reports Server (NTRS)

    Belanger, Jacques; Hornung, Hans G.

    1992-01-01

    A combustion driven shock tunnel was designed and built at GALCIT to supply the hypersonic facility T5 with 'hot' hydrogen for mixing and combustion experiments. This system was chosen over other options for better flexibility and for safety reasons. The shock tunnel is described and the overall efficiency of the system is discussed. The biggest challenge in the design was to synchronize the combustion driven shock tunnel with T5. To do so, the main diaphragm of the combustion driven shock tunnel is locally melted by an electrical discharge. This local melting is rapidly followed by the complete collapse of the diaphragm in a very repeatable way. A first set of experiments on supersonic hydrogen transverse jets over a flat plate have just been completed with the system and some of the preliminary results are presented.

  12. An analysis of combustion studies in shock expansion tunnels and reflected shock tunnels

    NASA Technical Reports Server (NTRS)

    Jachimowski, Casimir J.

    1992-01-01

    The effect of initial nonequilibrium dissociated air constituents on the combustion of hydrogen in high-speed flows for a simulated Mach 17 flight condition was investigated by analyzing the results of comparative combustion experiments performed in a reflected shock tunnel test gas and in a shock expansion tunnel test gas. The results were analyzed and interpreted with a one-dimensional quasi-three-stream combustor code that includes finite rate combustion chemistry. The results of this study indicate that the combustion process is kinetically controlled in the experiments in both tunnels and the presence of the nonequilibrium partially dissociated oxygen in the reflected shock tunnel enhances the combustion. Methods of compensating for the effect of dissociated oxygen are discussed.

  13. 78 FR 46117 - National Tunnel Inspection Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-30

    ... in the Federal Register on July 22, 2010, at 75 FR 42643. That proposal did not address the.../onlinepubs/nchrp/docs/NCHRP20-07 (261)--FR.pdf. C. Best Practices for Roadway Tunnel Design, Construction... ANPRM on November 18, 2008, (73 FR 68365) to solicit public comments regarding 14 categories...

  14. Improved Solar-Cell Tunnel Junction

    NASA Technical Reports Server (NTRS)

    Daud, T.; Kachare, A.

    1986-01-01

    Efficiency of multiple-junction silicon solar cells increased by inclusion of p+/n+ tunnel junctions of highly doped GaP between component cells. Relatively low recombination velocity at GaP junction principal reason for recommending this material. Relatively wide band gap also helps increase efficiency by reducing optical losses.

  15. Sources of compass error in tunnel mapping

    SciTech Connect

    Yow, J.L. Jr.

    1982-05-01

    Six sets of compass measurements were performed in tunnels in igneous rock at the Nevada Test Site. The measurement sets were analyzed to evaluate the influences of wire mesh, rock bolts, mining equipment, and steel arches on compass-based geologic mapping work.

  16. A Student-Built Scanning Tunneling Microscope

    ERIC Educational Resources Information Center

    Ekkens, Tom

    2015-01-01

    Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

  17. Scanning tunneling microscopy: Energetics from statistical analysis

    SciTech Connect

    Feibelman, P.J.

    1995-10-15

    The attraction between two Fe atoms adsorbed on Fe(100) should be much too weak to produce the 0.5--0.7-eV bond that has been deduced by analyzing scanning tunneling micrographs. The assumption that adatom diffusion proceeds by the same mechanism at high and low temperatures may be the source of the discrepancy.

  18. Resonant tunnelling in a quantum oxide superlattice

    SciTech Connect

    Choi, Woo Seok; Lee, Sang A.; You, Jeong Ho; Lee, Suyoun; Lee, Ho Nyung

    2015-06-24

    Resonant tunneling is a quantum mechanical process that has long been attracting both scientific and technological attention owing to its intriguing underlying physics and unique applications for high-speed electronics. The materials system exhibiting resonant tunneling, however, has been largely limited to the conventional semiconductors, partially due to their excellent crystalline quality. Here we show that a deliberately designed transition metal oxide superlattice exhibits a resonant tunneling behaviour with a clear negative differential resistance. The tunneling occurred through an atomically thin, lanthanum δ- doped SrTiO3 layer, and the negative differential resistance was realized on top of the bi-polar resistance switching typically observed for perovskite oxide junctions. This combined process resulted in an extremely large resistance ratio (~105) between the high and low resistance states. Lastly, the unprecedentedly large control found in atomically thin δ-doped oxide superlattices can open a door to novel oxide-based high-frequency logic devices.

  19. Resonant tunnelling in a quantum oxide superlattice

    DOE PAGES

    Choi, Woo Seok; Lee, Sang A.; You, Jeong Ho; Lee, Suyoun; Lee, Ho Nyung

    2015-06-24

    Resonant tunneling is a quantum mechanical process that has long been attracting both scientific and technological attention owing to its intriguing underlying physics and unique applications for high-speed electronics. The materials system exhibiting resonant tunneling, however, has been largely limited to the conventional semiconductors, partially due to their excellent crystalline quality. Here we show that a deliberately designed transition metal oxide superlattice exhibits a resonant tunneling behaviour with a clear negative differential resistance. The tunneling occurred through an atomically thin, lanthanum δ- doped SrTiO3 layer, and the negative differential resistance was realized on top of the bi-polar resistance switching typicallymore » observed for perovskite oxide junctions. This combined process resulted in an extremely large resistance ratio (~105) between the high and low resistance states. Lastly, the unprecedentedly large control found in atomically thin δ-doped oxide superlattices can open a door to novel oxide-based high-frequency logic devices.« less

  20. WIND TUNNEL SIMULATIONS OF POLLUTION FROM ROADWAYS

    EPA Science Inventory

    A wind tunnel study has been conducted to examine the influence of roadway configurations and nearby structures on the flow and dispersion of traffic related pollutant concentrations within a few hundred meters of the roadway. The study focused four selected configurations (all w...

  1. The electron-hole bilayer tunnel FET

    NASA Astrophysics Data System (ADS)

    Lattanzio, Livio; De Michielis, Luca; Ionescu, Adrian M.

    2012-08-01

    We propose a novel tunnel field-effect transistor (TFET) concept called the electron-hole bilayer TFET (EHBTFET). This device exploits the carrier tunneling through a bias-induced electron-hole bilayer in order to achieve improved switching and higher drive currents when compared to a lateral p-i-n junction TFET. The device principle and performances are studied by 2D numerical simulations. Output and transfer characteristics, as well as the impact of back gate bias, silicon thickness and gate length on the device behavior are evaluated. Device performances are compared for Si and Ge implementations. Nearly ideal average subthreshold slope (SSAVG ∼ 10 mV/dec over 7 decades of current) and ION/IOFF > 108 at VD = VG = 0.5 V are obtained, due to the OFF-ON binary transition which leads to the abrupt onset of the band-to-band tunneling inside the semiconductor channel. Remarkably, for Ge EHBTFETs the ION (∼11 μA/μm at VDD = 0.5 V) is 10× larger than in Ge tunnel FETs and 380× larger than in Si EHBTFETs.

  2. Tunnelling Problems in Older Sand Formations

    NASA Astrophysics Data System (ADS)

    Nieuwenhuis, Jan Dirk; Verruijt, Arnold

    In its deepest stretch, 60 m below o.d. and water level, the Westerschelde tunnel trace below the estuary in the Southwestern part of the Netherlands, crosses the lower Oligocene Rupel clay (Boom clay) and the Sands of Berg. Expected problems such as small penetration rates and difficult steerability of the TBM did not occur but surprisingly high radial pressures deformed the shields tail section to such an extent that concrete rings of the permanent tunnel could not be emplaced. In retrospect after finishing the tunnel and cumbersome remedial measures the sands of Berg, known to be dense and strong, appear to exhibit very strong dilatancy when axially sheared by the TBM. Some buckling computations and an estimate of dilatant effects are presented together with educated (and now confirmed) guess work on diagenetic effects such as recrystallization and cementation. It seems wise to warn designers of shallow tunnels crossing tertiary sand formations for unexpected forces on shield and cutting wheel due to diagenetic structuring of these old sands.

  3. TBM tunneling on the Yucca Mountain Project

    SciTech Connect

    Morris, J.P.; Hansmire, W.H. |

    1995-03-01

    The US Department of Energy`s (DOE) Yucca Mountain Project (YMP) is a scientific endeavor to determine the suitability of Yucca Mountain for the first long-term, high-level nuclear waste repository in the United States. The current status of this long-term project from the construction perspective is described. A key element is construction of the Exploratory Studies Facility (ESF) Tunnel, which is being excavated with a 7.6 m (25 ft) diameter tunnel boring machine (TBM). Development of the ESF may include the excavation of over 15 km (9.3 mi) of tunnel varying in size from 3.0 to 7.6 m (10 to 25 ft). Prior to construction, extensive constructability reviews were an interactive part of the final design. The intent was to establish a constructable design that met the long-term stability requirements for radiological safety of a future repository, while maintaining flexibility for the scientific investigations and acceptable tunneling productivity.

  4. A construction technique for wind tunnel models

    NASA Technical Reports Server (NTRS)

    Lawing, P. L.; Sandefur, P. G., Jr.; Wood, W. H.

    1981-01-01

    High strength, good surface finish, and corrosion resistance are imparted to miniature wind tunnel models by machining pressure channels as integral part of model. Pattern for pressure channels is scribed, machined, or photoetched before channels are drilled. Mating surfaces for channels are flashed and then diffusion brazed together.

  5. Bilateral carpal tunnel syndrome in Graves' disease.

    PubMed

    Manganelli, P; Pavesi, G; Salaffi, F

    1987-01-01

    Carpal tunnel syndrome (CTS) may be associated with endocrinopathies, such as hypothyroidism and acromegaly. A direct relationship between CTS and hyperthyroidism has recently been suggested. We now report a case in which bilateral CTS developed after treatment of Graves' disease, thus, questioning the possibility of a relationship between these two disease processes.

  6. Tunneling in cuprate and bismuthate superconductors

    SciTech Connect

    Zasadzinski, J.F.; Huang, Qiang; Tralshawala, N. . Dept. of Physics); Gray, K.E. )

    1991-10-01

    Tunneling measurements using a point-contact technique are reported for the following high temperature superconducting oxides: Ba{sub 1-x}K{sub x}BiO{sub 3}(BKBO), Nd{sub 2-x}Ce{sub x}CuO{sub 4}(NCCO), Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 7}(BSCCO) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub x} (TBCCO). For the bismuthate, BKBO, ideal, S-I-N tunneling characteristics are observed using a Au tip. The normalized conductance is fitted to a BCS density of states and thermal smearing only proving there is no fundamental limitation in BKBO for device applications. For the cuprates, the normalized conductance displays BCS-like characteristics, but with a broadening larger than from thermal smearing. Energy gap values are presented for each material. For BKBO and NCCO the Eliashberg functions, {alpha}{sup 2}F({omega}), obtained from the tunneling are shown to be in good agreement with neutron scattering results. Proximity effect tunneling studies are reported for Au/BSCCO bilayers and show that the energy gap of BSCCO can be observed through Au layers up to 600 {Angstrom} thick.

  7. Tunneling in cuprate and bismuthate superconductors

    SciTech Connect

    Zasadzinski, J.F.; Huang, Qiang; Tralshawala, N.; Gray, K.E.

    1991-10-01

    Tunneling measurements using a point-contact technique are reported for the following high temperature superconducting oxides: Ba{sub 1-x}K{sub x}BiO{sub 3}( BKBO ), Nd{sub 2-x}Ce{sub x}CuO{sub 4}( NCCO ), Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 7}( BSCCO ) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub x} ( TBCCO ). For the bismuthate, BKBO, ideal, S-I-N tunneling characteristics are observed using a Au tip. The normalized conductance is fitted to a BCS density of states and thermal smearing only proving there is no fundamental limitation in BKBO for device applications. For the cuprates, the normalized conductance displays BCS-like characteristics, but with a broadening larger than from thermal smearing. Energy gap values are presented for each material. For BKBO and NCCO the Eliashberg functions, {alpha}{sup 2}F({omega}), obtained from the tunneling are shown to be in good agreement with neutron scattering results. Proximity effect tunneling studies are reported for Au/BSCCO bilayers and show that the energy gap of BSCCO can be observed through Au layers up to 600 {Angstrom} thick.

  8. Planar Tunneling Spectroscopy of Graphene Nanodevices

    NASA Astrophysics Data System (ADS)

    Wang, Joel I.-Jan; Bretheau, Landry; Pisoni, Riccardo; Watanabe, Kenji; Taniguchi, Takashi; Jarillo-Herrero, Pablo

    2-D Van-der-Waals mesoscopic physics have seen a rapid development in the last 10 years, with new materials each year added to the toolbox. Stacking them like Lego enables the combination of their individual electronic properties. In particular, hexagonal boron nitride, which is an insulator, gives the possibility to perform planar (2-D to 2-D) tunneling spectroscopy within this type of heterostructures. Unlike standard transport measurements, tunneling spectroscopy enables to probe the electronic properties in the energy domain. Moreover, since planar tunneling probes a large area of the system, global quantum features such as quantum Hall effect, superconducting proximity effect or quantum confinement can be investigated. In this talk, we will present implementation of heterostructures consisting of graphene, hexagonal boron nitride, and graphite, fabricated for planar tunneling spectroscopy. In order to reveal the intrinsic properties of materials, the fabrication scheme aims at preserving the pristine nature of the 2-DEGS as well as minimizing the doping introduced by external probes. As a demonstration, measurements of these devices in normal states, high magnetic field environment, and induced superconducting state will be presented.

  9. Electron tunnelling into amorphous germanium and silicon.

    NASA Technical Reports Server (NTRS)

    Smith, C. W.; Clark, A. H.

    1972-01-01

    Measurements of tunnel conductance versus bias, capacitance versus bias, and internal photoemission were made in the systems aluminum-oxide-amorphous germanium and aluminium-oxide-amorphous silicon. A function was extracted which expresses the deviation of these systems from the aluminium-oxide-aluminium system.

  10. Aircraft Engineering Conference 1934 - Full Scale Tunnel

    NASA Technical Reports Server (NTRS)

    1934-01-01

    Gathered together in the only facility big enough to hold them, attendees at Langleys 1934 aircraft Engineering Conference pose in the Full Scale Wind Tunnel underneath a Boeing P-26A Peashooter. Present, among other notables, were Orville Wright, Charles Lindbergh, and Howard Hughes.

  11. B-Target Room Tunnel Redesigned

    SciTech Connect

    Esfandiari, Reza; /San Jose State U. /SLAC

    2010-08-25

    Several groups at SLAC National Accelerator Laboratory are currently working on a RF Modulator prototype for a future linear collider known as the International Linear Collider (ILC). The ILC runs using about a 1000 Klystrons which create high power carrier waves for the particle acceleration. Klystrons receive their electrical input power from modulators. In order to move beyond the prototype phase, the laboratory might expand its ground base further down a tunnel located at the End Station B (ESB) in order to house four new Klystron Modulator Test Stations. This area is known as the B-Target Room Tunnel, and the task was to redesign the tunnel layout for the upcoming changes. The project first began by collecting substantial amount of information about the prototyped project, the tunnel and the researchers feedback of what they would like to see in the upcoming design. Subsequent to numerous planning and presentations, one particular design was. Calculations for this design were then performed for the most complex aspects of the project. Based on the results of the calculations, specific sample beams, welds, bolts and materials were chosen for the possible future construction.

  12. Local trap spectroscopy in superconducting tunnel junctions

    SciTech Connect

    Kozorezov, A. G.; Wigmore, J. K.; Peacock, A.; Poelaert, A.; Verhoeve, P.; den Hartog, R.; Brammertz, G.

    2001-06-04

    We show that thermal activation of quasiparticles from local traps is responsible for the temperature variation of responsivity observed for some superconducting tunneling junction photon detectors. With this model, the depth of the local traps in two different proximized Ta structures was found to be the same, 0.20{+-}0.02 meV. {copyright} 2001 American Institute of Physics.

  13. The Path Decomposition Expansion and Multidimensional Tunneling

    NASA Astrophysics Data System (ADS)

    Auerbach, Assa

    The dissertation consists of two main topics. (a) The Path Decomposition Expansion (PDX): A new path integral technique which allows us to break configuration space into disjoint regions, and express the dynamics of the full system in terms of its parts. (b) The application of the PDX and semiclassical methods for solving quantum -mechanical problems in multidimensions. The result is a conceptually simple, computationally straightforward method for calculating tunneling effects in complicated multidimensional potentials, even in cases where the nature of the states in the classically allowed regions in nontrivial. Algorithms for computing tunneling effects in general classes of problems are obtained. The detailed solutions to several model problems are presented. These enable us to define various well -controlled approximation schemes, which help to reduce the dimensions of complicated tunneling calculations in real physical systems. The dramatic effects of transverse fluctuations on the asymptotic behavior of the groundstate tunnel-splitting are studied also in potentials with non -quadratic minima where standard instanton techniques fail. The power of the PDX is demonstrated by a calculation of the optical absorption coefficient of trans-polyacetylene where large amplitude (non-perturbative) quantum fluctuations of the lattice play an important role in determining the sub-gap absorption tail. Good agreement with experimental data is found, and suggestions for further measurements in this regime are made.

  14. Nonequilibrium transport in superconducting tunneling structures.

    SciTech Connect

    Chtchelkatchev, N. M.; Vinokur, V. M.; Baturina, T. I.

    2010-12-01

    We derive the current-voltage (I-V) characteristics of far from equilibrium superconducting tunneling arrays and find that the energy relaxation ensuring the charge transfer occurs in two stages: (i) the energy exchange between charge carriers and the intermediate bosonic agent, environment, and (ii) relaxing the energy further to the (phonon) thermostat, the bath, provided the rate of the environmental modes-phonon interactions is slower than their energy exchange rate with the tunneling junction. For a single junction we find I {proportional_to} (V/R)ln({Lambda}/V), where R is the bare tunnel resistance of the junction and {Lambda} is the high energy cut-off of the electron-environment interaction. In large tunneling arrays comprised of macroscopic number of junctions, low-temperature transport is governed by the cotunneling processes losing energy to the electron-hole environment. Below some critical temperature, T*, the Coulomb interactions open a finite gap in the environment excitations spectrum blocking simultaneously Cooper pair and normal excitations currents through the array; this is the microscopic mechanism of the insulator-to-superinsulator transition.

  15. Boundary conditions in tunneling via quantum hydrodynamics

    NASA Technical Reports Server (NTRS)

    Nassar, Antonio B.

    1993-01-01

    Via the hydrodynamical formulation of quantum mechanics, an approach to the problem of tunneling through sharp-edged potential barriers is developed. Above all, it is shown how more general boundary conditions follow from the continuity of mass, momentum, and energy.

  16. Revealing the quantum regime in tunnelling plasmonics.

    PubMed

    Savage, Kevin J; Hawkeye, Matthew M; Esteban, Rubén; Borisov, Andrei G; Aizpurua, Javier; Baumberg, Jeremy J

    2012-11-22

    When two metal nanostructures are placed nanometres apart, their optically driven free electrons couple electrically across the gap. The resulting plasmons have enhanced optical fields of a specific colour tightly confined inside the gap. Many emerging nanophotonic technologies depend on the careful control of this plasmonic coupling, including optical nanoantennas for high-sensitivity chemical and biological sensors, nanoscale control of active devices, and improved photovoltaic devices. But for subnanometre gaps, coherent quantum tunnelling becomes possible and the system enters a regime of extreme non-locality in which previous classical treatments fail. Electron correlations across the gap that are driven by quantum tunnelling require a new description of non-local transport, which is crucial in nanoscale optoelectronics and single-molecule electronics. Here, by simultaneously measuring both the electrical and optical properties of two gold nanostructures with controllable subnanometre separation, we reveal the quantum regime of tunnelling plasmonics in unprecedented detail. All observed phenomena are in good agreement with recent quantum-based models of plasmonic systems, which eliminate the singularities predicted by classical theories. These findings imply that tunnelling establishes a quantum limit for plasmonic field confinement of about 10(-8)λ(3) for visible light (of wavelength λ). Our work thus prompts new theoretical and experimental investigations into quantum-domain plasmonic systems, and will affect the future of nanoplasmonic device engineering and nanoscale photochemistry.

  17. Employees' Knowledge of Carpal Tunnel Syndrome.

    ERIC Educational Resources Information Center

    Gandy-Goldston, Terrie M.

    A study examined employees' knowledge of the causes of carpal tunnel syndrome (CTS), its prevention, and their legal rights after being diagnosed with CTS. A 24-item questionnaire was administered to a random sample of 30 Chicago-area employees who had been afflicted with CTS. Of those surveyed, 99% considered their CTS injury related to their…

  18. Carpal Tunnel Syndrome in ARL Libraries.

    ERIC Educational Resources Information Center

    Thornton, Joyce K.

    1997-01-01

    A survey of 72 member libraries in the Association of Research Libraries revealed the incidence of carpal tunnel syndrome (CTS) and the measures taken to cope with it. Recommends implementing proactive ergonomics programs; soliciting staff input for solutions; providing report guidelines; using external help; stressing preventive measures and…

  19. Vector particles tunneling from BTZ black holes

    NASA Astrophysics Data System (ADS)

    Chen, Ge-Rui; Zhou, Shiwei; Huang, Yong-Chang

    2015-11-01

    In this paper we investigate vector particles' Hawking radiation from a Banados-Teitelboim-Zanelli (BTZ) black hole. By applying the Wentzel-Kramers-Brillouin (WKB) approximation and the Hamilton-Jacobi ansatz to the Proca equation, we obtain the tunneling spectrum of vector particles. The expected Hawking temperature is recovered.

  20. Aeronautical Facilities Catalogue. Volume 1: Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Penaranda, F. E. (Compiler); Freda, M. S. (Compiler)

    1985-01-01

    Domestic and foreign wind tunnel facilities are enumerated and their technical parameters are described. Data pertinent to managers and engineers are presented. Facilities judged comparable in testing capability are noted and grouped together. Several comprehensive cross-indexes and charts are included.

  1. Prismatic Blade Measuring on a Wind Tunnel

    NASA Astrophysics Data System (ADS)

    Epikaridis, P.; Sedlak, k.; Stech, J.

    2013-04-01

    The results from measurement on the straight blade cascade are presented in the paper. The cascade is placed at the outlet of wind tunnel in ŠKODA POWER experimental base. The results in the form of velocity and loss fields behind blade cascade as well as the distribution of the loss coefficient in selected cross-section are evaluated.

  2. Multi-dimensional tunnelling and complex momentum

    NASA Technical Reports Server (NTRS)

    Bowcock, Peter; Gregory, Ruth

    1991-01-01

    The problem of modeling tunneling phenomena in more than one dimension is examined. It is found that existing techniques are inadequate in a wide class of situations, due to their inability to deal with concurrent classical motion. The generalization of these methods to allow for complex momenta is shown, and improved techniques are demonstrated with a selection of illustrative examples. Possible applications are presented.

  3. Electric field modulation of tunneling anisotropic magnetoresistance in tunnel junctions with antiferromagnetic electrodes

    NASA Astrophysics Data System (ADS)

    Goto, Minori; Nawaoka, Kohei; Miwa, Shinji; Hatanaka, Shohei; Mizuochi, Norikazu; Suzuki, Yoshishige

    2016-08-01

    We present electric field modulation of tunneling anisotropic magnetoresistance (TAMR) in MnIr|MgO|Ta tunnel junctions. TAMR enables direct observation of the antiferromagnetic spin direction at the MnIr|MgO interface. We found that the shape of magnetoresistance (MR) curve can be modulated by an electric field, which can be explained by electric field modulation of the interfacial magnetic anisotropy at MnIr|MgO.

  4. N-231 High Reynolds Number Channel Facility (An example of a Versatile Wind Tunnel) Tunnel 1 I is a

    NASA Technical Reports Server (NTRS)

    1980-01-01

    N-231 High Reynolds Number Channel Facility (An example of a Versatile Wind Tunnel) Tunnel 1 I is a blowdown Facility that utilizes interchangeable test sections and nozzles. The facility provides experimental support for the fluid mechanics research, including experimental verification of aerodynamic computer codes and boundary-layer and airfoil studies that require high Reynolds number simulation. (Tunnel 1)

  5. Surface Wave Imaging to Detect Tunnels

    NASA Astrophysics Data System (ADS)

    Miller, R. D.; Ballard, R. F.; Park, C. B.; Xia, J.

    2002-05-01

    Unauthorized infiltration into the U.S. is possible through the air, from the sea, across the land, and under the ground. Several near-surface geophysical techniques have been evaluated and in certain situations show promise in detecting underground activity related to tunneling. Recently developed acquisition and analysis techniques for multi-channel surface wave imaging has opened the door to a vast number of near-surface applications including anomaly detection and delineation, specifically tunnels. Routine scanning of the subsurface for anomalies unique to tunneling activities using surface waves can be done at relatively high production rates with confident interpretations made by minimally trained technical staff. Acquisition tests have proven that appropriate coupling for accurate recording of surface waves can be established with only pressure contact to the earth's surface, unlike body wave surveying in which coupling is optimized by invasive "planting." Marine streamer technology adapted to land provides near-continuous acquisition of 2-D profiles using pressure-coupled sources and receivers. Once parameters in a particular area have been selected, processing routines can be automated with pattern recognition and differencing routines used to identify potential targets. These nearly fully automated interpretive techniques could be almost real-time with preliminary results available within minutes of data acquisition. This tool is well suited for either initial reconnaissance surveys or differencing of periodic "patrol" surveys. A system using surface wave imaging technology could routinely monitor the shallow subsurface along the U.S. borders to recognize changes in physical earth properties likely related to tunneling. To evaluate the potential of this imaging technology a feasibility study was conducted in an area along the California/Mexico border with two sites in reasonably close proximity: one with a known tunnel and the other with a suspected

  6. Evanescent Modes and Tunnelling Instantaneously Act at a Distance

    SciTech Connect

    Nimtz, Guenter; Stahlhofen, Alfons A.

    2008-03-06

    Photonic tunnelling experiments have shown that i) the Einstein energy relation is violated, ii) the tunnelling process is non-local, iii) the signal velocity is faster than light, i.e. superluminal, iv) the tunnelling signal is not observable, since photonic tunnelling is described by virtual photons, and v) according to the experimental results the signal velocity is infinite inside the barriers, implying that tunnelling instantaneously acts at a distance. We think these properties are not compatible with the claims of many text books on Special Relativity.

  7. 2. West portal of Tunnel 22, view to the northwest, ...

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

    2. West portal of Tunnel 22, view to the northwest, 135mm lens. Note the use of concrete face and wingwalls, with dressed stone voussoirs, wingwall coping, concrete parapet with stone belt course and coping, and rubble masonry slope protection flanking the portal. Built for the Oregon Eastern, this Southern Pacific Common Standard tunnel is contemporary with those built by different contractors for the California Northeastern at the south end of the Natron Cutoff (see Tunnel 17, HAER CA-218, and Tunnel 18, HAER CA-219). - Southern Pacific Railroad Natron Cutoff, Tunnel 22, Milepost 581.85, Oakridge, Lane County, OR

  8. 2. West portal of Tunnel 23, view to the westnorthwest, ...

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

    2. West portal of Tunnel 23, view to the west-northwest, 135mm lens. Note the use of concrete face and wingwalls, with dressed stone voussoirs, wingwall coping, concrete parapet with stone belt course and coping, and rubble masonry slope protection flanking the portal. Built for the Oregon Eastern, this Southern Pacific Common Standard tunnel is contemporary with those built by different contractors for the California Northeastern at the south end of the Natron Cutoff (see Tunnel 17, HAER CA-218, and Tunnel 18, HAER CA-219). - Southern Pacific Railroad Natron Cutoff, Tunnel 23, Milepost 584.5, Westfir, Lane County, OR

  9. Acoustic measurement study 40 by 80 foot subsonic wind tunnel

    NASA Technical Reports Server (NTRS)

    1974-01-01

    An acoustical study conducted during the period from September 1, 1973 to April 30, 1974 measured sound pressure levels and vibration amplitudes inside and outside of the subsonic tunnel and on the tunnel structure. A discussion of the technical aspects of the study, the field measurement and data reduction procedures, and results are presentd, and conclusions resulting from the study which bear upon near field and far field tunnel noise, upon the tunnel as an acoustical enclosure, and upon the sources of noise within the tunnel drive system are given.

  10. Single-photon tunneling via localized surface plasmons.

    PubMed

    Smolyaninov, I I; Zayats, A V; Gungor, A; Davis, C C

    2002-05-01

    Strong evidence of a single-photon tunneling effect, a direct analog of single-electron tunneling, has been obtained in the measurements of light tunneling through individual subwavelength pinholes in a gold film covered with a layer of polydiacetylene. The transmission of some pinholes reached saturation because of the optical nonlinearity of polydiacetylene at a very low light intensity of a few thousand photons per second. This result is explained theoretically in terms of a "photon blockade," similar to the Coulomb blockade phenomenon observed in single-electron tunneling experiments. Single-photon tunneling may find applications in the fields of quantum communication and information processing.

  11. Thermal creation of a spin current by Seebeck spin tunneling

    NASA Astrophysics Data System (ADS)

    Jansen, R.; Le Breton, J. C.; Deac, A. M.; Saito, H.; Yuasa, S.

    2013-09-01

    The thermoelectric analog of spin-polarized tunneling, namely Seebeck spin tunneling, is a recently discovered phenomenon that arises from the spin-dependent Seebeck coefficient of a magnetic tunnel contact. In a tunnel junction with one ferromagnetic electrode and one non-magnetic electrode, a temperature difference between the two electrodes creates a spin current across the contact. Here, the basic principle and the observation of Seebeck spin tunneling are described. It is shown how it can be used to create a spin accumulation in silicon driven by a heat flow across a magnetic tunnel contact, without a charge tunnel current. The sign of the spin current depends on the direction of the heat flow, whereas its magnitude is anisotropic, i.e., dependent on the absolute orientation of the magnetization of the ferromagnet. The connection between Seebeck spin tunneling and the tunnel magneto-Seebeck effect, observed in metal magnetic tunnel junctions, is also clarified. Seebeck spin tunneling may be used to convert waste heat into useful thermal spin currents that aid or replace electrical spin current, and thereby improve the energy efficiency of spintronic devices and technologies.

  12. Videogrammetric Model Deformation Measurement Technique for Wind Tunnel Applications

    NASA Technical Reports Server (NTRS)

    Barrows, Danny A.

    2006-01-01

    Videogrammetric measurement technique developments at NASA Langley were driven largely by the need to quantify model deformation at the National Transonic Facility (NTF). This paper summarizes recent wind tunnel applications and issues at the NTF and other NASA Langley facilities including the Transonic Dynamics Tunnel, 31-Inch Mach 10 Tunnel, 8-Ft high Temperature Tunnel, and the 20-Ft Vertical Spin Tunnel. In addition, several adaptations of wind tunnel techniques to non-wind tunnel applications are summarized. These applications include wing deformation measurements on vehicles in flight, determining aerodynamic loads based on optical elastic deformation measurements, measurements on ultra-lightweight and inflatable space structures, and the use of an object-to-image plane scaling technique to support NASA s Space Exploration program.

  13. Superpoissonian shot noise in organic magnetic tunnel junctions

    SciTech Connect

    Cascales, Juan Pedro; Martinez, Isidoro; Aliev, Farkhad G.; Hong, Jhen-Yong; Lin, Minn-Tsong; Szczepański, Tomasz; Dugaev, Vitalii K.; Barnaś, Józef

    2014-12-08

    Organic molecules have recently revolutionized ways to create new spintronic devices. Despite intense studies, the statistics of tunneling electrons through organic barriers remains unclear. Here, we investigate conductance and shot noise in magnetic tunnel junctions with 3,4,9,10-perylene-teracarboxylic dianhydride (PTCDA) barriers a few nm thick. For junctions in the electron tunneling regime, with magnetoresistance ratios between 10% and 40%, we observe superpoissonian shot noise. The Fano factor exceeds in 1.5–2 times the maximum values reported for magnetic tunnel junctions with inorganic barriers, indicating spin dependent bunching in tunneling. We explain our main findings in terms of a model which includes tunneling through a two level (or multilevel) system, originated from interfacial bonds of the PTCDA molecules. Our results suggest that interfaces play an important role in the control of shot noise when electrons tunnel through organic barriers.

  14. Aeroacoustic research in wind tunnels: A status report

    NASA Technical Reports Server (NTRS)

    Bender, J.; Arndt, R. E. A.

    1973-01-01

    The increasing attention given to aerodynamically generated noise brings into focus the need for quality experimental research in this area. To meet this need several specialized anechoic wind tunnels have been constructed. In many cases, however, budgetary constraints and the like make it desirable to use conventional wind tunnels for this work. Three basic problems are inherent in conventional facilities: (1) high background noise, (2) strong frequency dependent reverberation effects, and (3) unique instrumentation problems. The known acoustic characteristics of several conventional wind tunnels are evaluated and data obtained in a smaller 4- x 5-foot wind tunnel which is convertible from a closed jet to an open jet mode are presented. The data from these tunnels serve as a guideline for proposed modifications to a 7- x 10-foot wind tunnel. Consideration is given to acoustic treatment in several different portions of the wind tunnel.

  15. PREFACE: Time-resolved scanning tunnelling microscopy Time-resolved scanning tunnelling microscopy

    NASA Astrophysics Data System (ADS)

    Zandvliet, Harold J. W.; Lin, Nian

    2010-07-01

    Scanning tunnelling microscopy has revolutionized our ability to image, manipulate, and investigate solid surfaces on the length scale of individual atoms and molecules. The strength of this technique lies in its imaging capabilities, since for many scientists 'seeing is believing'. However, scanning tunnelling microscopy also suffers from a severe limitation, namely its poor time resolution. Recording a scanning tunnelling microscopy image typically requires a few tens of seconds for a conventional scanning tunnelling microscope to a fraction of a second for a specially designed fast scanning tunnelling microscope. Designing and building such a fast scanning tunnelling microscope is a formidable task in itself and therefore, only a limited number of these microscopes have been built [1]. There is, however, another alternative route to significantly enhance the time resolution of a scanning tunnelling microscope. In this alternative method, the tunnelling current is measured as a function of time with the feedback loop switched off. The time resolution is determined by the bandwidth of the IV converter rather than the cut-off frequency of the feedback electronics. Such an approach requires a stable microscope and goes, of course, at the expense of spatial information. In this issue, we have collected a set of papers that gives an impression of the current status of this rapidly emerging field [2]. One of the very first attempts to extract information from tunnel current fluctuations was reported by Tringides' group in the mid-1990s [3]. They showed that the collective diffusion coefficient can be extracted from the autocorrelation of the time-dependent tunnelling current fluctuations produced by atom motion in and out of the tunnelling junction. In general, current-time traces provide direct information on switching/conformation rates and distributions of residence times. In the case where these processes are thermally induced it is rather straightforward to map

  16. 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

  17. Tunnel magnetoresistance in epitaxially grown magnetic tunnel junctions using Heusler alloy electrode and MgO barrier

    SciTech Connect

    Tsunegi, S.; Sakuraba, Y.; Oogane, M.; Telling, N. D.; Shelford, L. R.; Arenholz, E.; van der Laan, G.; Hicken, R. J.; Takanashi, K.; Ando, Y.

    2009-07-01

    Epitaxially grown magnetic tunnel junctions (MTJs) with a stacking structure of Co{sub 2}MnSi/MgO/CoFe were fabricated. Their tunnel magnetoresistance (TMR) effects were investigated. The TMR ratio and tunnelling conductance characteristics of MTJs were considerably different between those with an MgO barrier prepared using sputtering (SP-MTJ) and those prepared using EB evaporation (EB-MTJ). The EB-MTJ exhibited a very large TMR ratio of 217% at room temperature and 753% at 2 K. The bias voltage dependence of the tunnelling conductance in the parallel magnetic configuration for the EB-MTJ suggests that the observed large TMR ratio at RT results from the coherent tunnelling process through the crystalline MgO barrier. The tunnelling conductance in the anti-parallel magnetic configuration suggests that the large temperature dependence of the TMR ratio results from the inelastic spin-flip tunnelling process.

  18. Review of Potential Wind Tunnel Balance Technologies

    NASA Technical Reports Server (NTRS)

    Burns, Devin E.; Williams, Quincy L.; Phillips, Ben D.; Commo, Sean A.; Ponder, Jonathon D.

    2016-01-01

    This manuscript reviews design, manufacture, materials, sensors, and data acquisition technologies that may benefit wind tunnel balances for the aerospace research community. Current state-of-the-art practices are used as the benchmark to consider advancements driven by researcher and facility needs. Additive manufacturing is highlighted as a promising alternative technology to conventional fabrication and has the potential to reduce both the cost and time required to manufacture force balances. Material alternatives to maraging steels are reviewed. Sensor technologies including piezoresistive, piezoelectric, surface acoustic wave, and fiber optic are compared to traditional foil based gages to highlight unique opportunities and shared challenges for implementation in wind tunnel environments. Finally, data acquisition systems that could be integrated into force balances are highlighted as a way to simplify the user experience and improve data quality. In summary, a rank ordering is provided to support strategic investment in exploring the technologies reviewed in this manuscript.

  19. A silicon nanocrystal tunnel field effect transistor

    SciTech Connect

    Harvey-Collard, Patrick; Drouin, Dominique; Pioro-Ladrière, Michel

    2014-05-12

    In this work, we demonstrate a silicon nanocrystal Field Effect Transistor (ncFET). Its operation is similar to that of a Tunnelling Field Effect Transistor (TFET) with two barriers in series. The tunnelling barriers are fabricated in very thin silicon dioxide and the channel in intrinsic polycrystalline silicon. The absence of doping eliminates the problem of achieving sharp doping profiles at the junctions, which has proven a challenge for large-scale integration and, in principle, allows scaling down the atomic level. The demonstrated ncFET features a 10{sup 4} on/off current ratio at room temperature, a low 30 pA/μm leakage current at a 0.5 V bias, an on-state current on a par with typical all-Si TFETs and bipolar operation with high symmetry. Quantum dot transport spectroscopy is used to assess the band structure and energy levels of the silicon island.

  20. Supersonic flow development in slotted wind tunnels

    NASA Technical Reports Server (NTRS)

    Ramaswamy, M. A.; Cornette, E. S.

    1980-01-01

    The development of test section slot shapes for achieving smooth supersonic Mach number distribution without overexpansion or waviness has, in the past, been largely an experimentally iterative or 'cutand try' procedure for each wind tunnel. To overcome the obvious disadvantages of time and expense involved in such an experimental approach, a simple analytical method has been developed to predict the supersonic flow development in a two-dimensional slotted tunnel given only the variation of open area ratio with downstream distance and the Mach number corresponding to the plenum static pressure. The well known method of characteristics is used with the constraint that it be compatible with the quadratic cross-flow pressure drop boundary condition at the slotted wall. The predicted results from this method agree remarkably well with the experimental calibration data available for some of the existing facilities. The flow mechanism responsible for causing overexpansion in the centerline Mach number distribution with some slot shapes has been brought to light.

  1. Quantum Tunneling Current in Nanoscale Plasmonic Junctions

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Lau, Y. Y.; Gilgenbach, R. M.

    2014-10-01

    Recently, electron tunneling between plasmonic resonators is found to support quantum plasmon resonances, which may introduce new regimes in nano-optoelectronics and nonlinear optics. This revelation is of substantial interest to the fundamental problem of electron transport in nano-scale, for example, in a metal-insulator-metal junction (MIM), which has been continuously studied for decades. Here, we present a self-consistent model of electron transport in a nano-scale MIM, by solving the coupled Schrödinger and Poisson equations. The effects of space charge, exchange-correlation, anode emission, and material properties of the electrodes and insulator are examined in detail. The self-consistent calculations are compared with the widely used Simmons formula. Transition from the direct tunneling regime to the space-charge-limited regime is demonstrated. This work was supported by AFOSR.

  2. Permafrost in the Fox Permafrost Tunnel

    NASA Astrophysics Data System (ADS)

    Shur, Y.; Bray, M. T.; Anderson, D. A.

    2002-12-01

    Geology, engineering geology, and paleo-geography of the Fox permafrost tunnel have been thoroughly studied (Sellmann, 1967, 1972; Hamilton and others, 1988, Huang, 1985, Johansen and others 1981, 1982,). Permafrost specific information from previous studies is very limited and controversial. We applied 3D mapping and a cryo-facial analysis to identify genesis and structure of permafrost and distinguish between original syngenetic permafrost and later alternations of soil and massive ice. By mapping the tunnel in a 3D framework, features which occur on both walls of the tunnel and at its ceiling can be connected. For example, ice wedge continuity can be seen along with the nature of their disruption patterns. Mapping is particularly useful for determining the history of syngenetic ice-wedges modification, which show most visually the timing patterns and nature of the events that transpired in modification of the original permafrost conditions. Main principals of the cryo-facial analysis (Katasonov, 1960) are based on dependence of shape and size of ice inclusions in permafrost on facial type of soil and consequently on morphological conditions in which soil was deposited and frozen such floodplain, slope, etc. Quaternary permafrost deposits have different ice content depending on its genesis and facial type. We analyzed the permafrost cryogenic structure and soil water content to distinguish between original syngetetic permafrost and soil altered later. In previous studies two layers of silt with a sub-horizontal thermal unconformity between them and two types of massive ice (ice-wedges and buried ice) have been identified. Our study contradicts to such descriptions. Ice, which was described previously as buried pond or aufeis, we identified as thermokarst-cave ice, which was formed inside permafrost in channels made by running water. Such thermokarst caves occur mainly in ice-wedges and seldom in ice-rich soil. Both situations take place in the Fox permafrost

  3. CFD applications in tunnel ventilation analysis

    SciTech Connect

    Ray, R.E. Jr.; Zigh, A.

    1999-07-01

    Longitudinal ventilation systems in transit and rail tunnels are typically analyzed by one dimensional ventilation network simulation models, such as the Subway Environment Simulation (SES) program. However, in recent years computational fluid dynamics (CFD) modeling has been utilized in conjunction with one-dimensional ventilation network programs to study ventilation systems for large volume spaces such as transit stations and rail overbuilds, as well as for vehicular tunnels. CFD uses numerical methods to simulate complex fluid flow phenomena in three dimensions to predict the distribution of velocity, pressure, temperature, concentration, and other relevant variables throughout the volume. This paper presents an overview of CFD study results from emergency ventilation analysis for a transit station and both emergency ventilation and diesel emissions analysis for a rail overbuild.

  4. Charged fermions tunneling from regular black holes

    SciTech Connect

    Sharif, M. Javed, W.

    2012-11-15

    We study Hawking radiation of charged fermions as a tunneling process from charged regular black holes, i.e., the Bardeen and ABGB black holes. For this purpose, we apply the semiclassical WKB approximation to the general covariant Dirac equation for charged particles and evaluate the tunneling probabilities. We recover the Hawking temperature corresponding to these charged regular black holes. Further, we consider the back-reaction effects of the emitted spin particles from black holes and calculate their corresponding quantum corrections to the radiation spectrum. We find that this radiation spectrum is not purely thermal due to the energy and charge conservation but has some corrections. In the absence of charge, e = 0, our results are consistent with those already present in the literature.

  5. Shock tunnel studies of scramjet phenomena

    NASA Technical Reports Server (NTRS)

    Morgan, R. G.; Paull, A.; Stalker, R. J.; Jacobs, P.; Morris, N.; Stringer, I.; Brescianini, C.

    1988-01-01

    Commissioning of the new T4 shock tunnel at the University of Queensland implied that it was no longer necessary to focus the work of the research group about an annual test series conducted in the T3 shock tunnel in Canberra. Therefore, it has been possible to organize a group for work to proceed along lines such that particular personnel are associated with particular project areas. The format of this report consists of a series of reports on specific project areas, with a brief general introduction commenting on each report. The introduction is structured by project areas, with the title of the relevant report stated under the project area heading. The reports themselves follow in the order of the project area headings.

  6. SUBSONIC WIND TUNNEL PERFORMANCE ANALYSIS SOFTWARE

    NASA Technical Reports Server (NTRS)

    Eckert, W. T.

    1994-01-01

    This program was developed as an aid in the design and analysis of subsonic wind tunnels. It brings together and refines previously scattered and over-simplified techniques used for the design and loss prediction of the components of subsonic wind tunnels. It implements a system of equations for determining the total pressure losses and provides general guidelines for the design of diffusers, contractions, corners and the inlets and exits of non-return tunnels. The algorithms used in the program are applicable to compressible flow through most closed- or open-throated, single-, double- or non-return wind tunnels or ducts. A comparison between calculated performance and that actually achieved by several existing facilities produced generally good agreement. Any system through which air is flowing which involves turns, fans, contractions etc. (e.g., an HVAC system) may benefit from analysis using this software. This program is an update of ARC-11138 which includes PC compatibility and an improved user interface. The method of loss analysis used by the program is a synthesis of theoretical and empirical techniques. Generally, the algorithms used are those which have been substantiated by experimental test. The basic flow-state parameters used by the program are determined from input information about the reference control section and the test section. These parameters were derived from standard relationships for compressible flow. The local flow conditions, including Mach number, Reynolds number and friction coefficient are determined for each end of each component or section. The loss in total pressure caused by each section is calculated in a form non-dimensionalized by local dynamic pressure. The individual losses are based on the nature of the section, local flow conditions and input geometry and parameter information. The loss forms for typical wind tunnel sections considered by the program include: constant area ducts, open throat ducts, contractions, constant

  7. Cryogenic Wind Tunnel Models. Design and Fabrication

    NASA Technical Reports Server (NTRS)

    Young, C. P., Jr. (Compiler); Gloss, B. B. (Compiler)

    1983-01-01

    The principal motivating factor was the National Transonic Facility (NTF). Since the NTF can achieve significantly higher Reynolds numbers at transonic speeds than other wind tunnels in the world, and will therefore occupy a unique position among ground test facilities, every effort is being made to ensure that model design and fabrication technology exists to allow researchers to take advantage of this high Reynolds number capability. Since a great deal of experience in designing and fabricating cryogenic wind tunnel models does not exist, and since the experience that does exist is scattered over a number of organizations, there is a need to bring existing experience in these areas together and share it among all interested parties. Representatives from government, the airframe industry, and universities are included.

  8. Subclinical carpal tunnel syndrome in acromegaly.

    PubMed

    Kameyama, S; Tanaka, R; Hasegawa, A; Tamura, T; Kuroki, M

    1993-08-01

    Median nerve conduction was studied in 16 acromegalic patients with asymptomatic carpal tunnel syndrome (CTS) to examine the incidence of subclinical CTS. Thirteen patients (81%) and 23 hands (72%) demonstrated subclinical CTS, 10 bilaterally and three unilaterally in the dominant hand. The incidence reflects the greater sensitivity of the inching method for detecting focal conduction abnormalities. Two of three patients without subclinical CTS showed normal plasma somatomedin-C concentration despite growth hormone hypersecretion. Following adenomectomy, nerve conduction normalized in only six hands (26%). The postoperative persistence of the conduction delay implies that irreversible narrowing of the carpal tunnel rather than reversible soft tissue edema is the principal cause of CTS associated with acromegaly.

  9. An Automatic Speed Control for Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Zahm, A F

    1928-01-01

    Described here is an automatic control that has been used in several forms in wind tunnels at the Washington Navy Yard. The form now in use with the 8-foot tunnel at the Navy Yard is considered here. Details of the design and operation of the automatic control system are given. Leads from a Pitot tube are joined to an inverted cup manometer located above a rheostat. When the sliding weight of this instrument is set to a given notch, say for 40 m.p.h, the beam tip vibrates between two electric contacts that feed the little motor. Thus, when the wind is too strong or too weak, the motor automatically throws the rheostat slide forward and backward. If it failed to function well, the operator would notice the effect on his meniscus, and would operate the hand control by merely pressing the switch.

  10. Interface composition in magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Schad, R.; Mayen, K.; McCord, J.; Allen, D.; Yang, D.; Tondra, M.; Wang, D.

    2001-06-01

    The magnetoresistance of magnetic tunnel junctions critically depends on the exact composition at the interfaces. As such the completeness of the oxidation process of the Al layer (used to produce Al2O3-based tunnel junctions) plays an essential role in the magnetoresistance. We studied the chemical properties of ferromagnet/Al2O3 interfaces as a function of original Al layer thickness. We have studied the concentrations of elementary and oxidized Al, Co, Ni, and Fe for varying roughness of the ferromagnetic layer. The oxidation process critically depends on the roughness of the underlying ferromagnetic (FM) layer. Al layers grown onto smooth FM layers oxidize homogeneously whereas Al layers grown on rough FM layers show a complicated oxidation behavior. Within the sensitivity of the analysis technique, we did not observe oxidation of the ferromagnetic layers, even for the overoxidized part of the samples.

  11. Gravitinos tunneling from traversable Lorentzian wormholes

    NASA Astrophysics Data System (ADS)

    Sakalli, I.; Ovgun, A.

    2015-09-01

    Recent research shows that Hawking radiation (HR) is also possible around the trapping horizon of a wormhole. In this article, we show that the HR of gravitino (spin-) particles from the traversable Lorentzian wormholes (TLWH) reveals a negative Hawking temperature (HT). We first introduce the TLWH in the past outer trapping horizon geometry (POTHG). Next, we derive the Rarita-Schwinger equations (RSEs) for that geometry. Then, using both the Hamilton-Jacobi (HJ) ansätz and the WKB approximation in the quantum tunneling method, we obtain the probabilities of the emission/absorption modes. Finally, we derive the tunneling rate of the emitted gravitino particles, and succeed to read the HT of the TLWH.

  12. Ultrasound-Assisted Endoscopic Carpal Tunnel Release.

    PubMed

    Ohuchi, Hiroshi; Hattori, Soichi; Shinga, Kotaro; Ichikawa, Ken; Yamada, Shin

    2016-06-01

    Various surgical procedures for carpal tunnel syndrome exist, such as open release, ultrasound-guided percutaneous release, and endoscopic release. Postoperative pain, scarring, and slow recovery to normal function are reported complications of open release. Damage to vessels and the median nerve and its branches underlying the transverse carpal ligament is a reported complication of ultrasound-guided percutaneous release. Damage to the superficial palmar arch and incomplete release are reported complications of endoscopic release. By performing endoscopic carpal tunnel release with ultrasound assistance, we could visualize neurovascular structures directly with the endoscope and also indirectly with ultrasound to minimize complications. We could also evaluate the morphologic changes of the median nerve dynamically before and after the release. We discuss the technique for this procedure and outline pearls and pitfalls for success. PMID:27656366

  13. Scanning tunneling microscope assembly, reactor, and system

    SciTech Connect

    Tao, Feng; Salmeron, Miquel; Somorjai, Gabor A

    2014-11-18

    An embodiment of a scanning tunneling microscope (STM) reactor includes a pressure vessel, an STM assembly, and three spring coupling objects. The pressure vessel includes a sealable port, an interior, and an exterior. An embodiment of an STM system includes a vacuum chamber, an STM reactor, and three springs. The three springs couple the STM reactor to the vacuum chamber and are operable to suspend the scanning tunneling microscope reactor within the interior of the vacuum chamber during operation of the STM reactor. An embodiment of an STM assembly includes a coarse displacement arrangement, a piezoelectric fine displacement scanning tube coupled to the coarse displacement arrangement, and a receiver. The piezoelectric fine displacement scanning tube is coupled to the coarse displacement arrangement. The receiver is coupled to the piezoelectric scanning tube and is operable to receive a tip holder, and the tip holder is operable to receive a tip.

  14. Attosecond science and the tunnelling time problem

    NASA Astrophysics Data System (ADS)

    Landsman, Alexandra S.; Keller, Ursula

    2015-01-01

    The question of how long it takes a particle to tunnel through a potential barrier has been a subject of intense theoretical debate for the last 80 years. In this decade of attosecond science, the answer to this question not only promises to deepen our understanding of fundamental quantum mechanics, but also has significant practical implications for how we interpret attosecond electron dynamics that underlie important phenomena in physics, chemistry and biology. Here we attempt to address this problem in the context of recent experimental measurements which use state-of-the-art ultrafast laser technology to resolve electron dynamics on the attosecond time-scale. This review therefore brings the theory of tunnelling time to the arena of ultrafast science, opening the door to improved resolution of, and cross-fertilization between, significant practical and fundamental questions in both fields.

  15. Photogrammetry Applied to Wind Tunnel Testing

    NASA Technical Reports Server (NTRS)

    Liu, Tian-Shu; Cattafesta, L. N., III; Radeztsky, R. H.; Burner, A. W.

    2000-01-01

    In image-based measurements, quantitative image data must be mapped to three-dimensional object space. Analytical photogrammetric methods, which may be used to accomplish this task, are discussed from the viewpoint of experimental fluid dynamicists. The Direct Linear Transformation (DLT) for camera calibration, used in pressure sensitive paint, is summarized. An optimization method for camera calibration is developed that can be used to determine the camera calibration parameters, including those describing lens distortion, from a single image. Combined with the DLT method, this method allows a rapid and comprehensive in-situ camera calibration and therefore is particularly useful for quantitative flow visualization and other measurements such as model attitude and deformation in production wind tunnels. The paper also includes a brief description of typical photogrammetric applications to temperature- and pressure-sensitive paint measurements and model deformation measurements in wind tunnels.

  16. Numerical wind tunnel and parallel FORTRAN

    NASA Astrophysics Data System (ADS)

    Nakamura, Takashi; Yoshida, Masahiro; Fukuda, Masahiro; Takamura, Moriyuki; Okada, Shin

    1992-12-01

    Computational Fluid Dynamics (CFD) requires computers 100 times faster than the Fujitsu VP400 in effective speed. Such a processor can be suitably called the 'Numerical Wind Tunnel'. Numerical Wind Tunnel (NWT) is a parallel computer system of a distributed memory architecture composed of vector processors connected through cross-bar network. In this report, the system configuration, processing element, and interconnection network and communication mechanism of the NWT are shown. Fundamental functions global data, parallel execution of DO-loop, and data decomposition and allocation, which the language-processor system has to provide in order to realize parallel execution on the NWT are also shown. FORTRAN 77 is chosen as a basic programming language for NWT and some compiler directives are added to make effective use of the NWT.

  17. Treatment of tunnel phobia: an experimental field study.

    PubMed

    Gotestam, K Gunnar; Svebak, Sven

    2009-01-01

    The opening of the deepest undersea tunnel in the world (264 m below sea level, 5600 m in length) replaced the ferry from the island of Hitra to the mainland in Norway. This event provoked phobic anxiety for traveling through the undersea tunnel in a number of individuals in the area. A treatment program for tunnel phobia was designed to test whether such a phobia could be mitigated by procedures previously proven effective in the treatment of other phobias. The program was presented to 18 persons with a specific phobia for tunnels and included a general discussion on the construction of undersea tunnels, given by an engineer from the tunnel construction company, and on phobic anxiety. It further consisted of gradual exposure to the tunnel in situ. Treatment effects were strong. All patients were able to travel on their own by car through the tunnel after the treatment. Their somatic complaints and phobic thoughts related to the tunnel were substantially reduced, and their mastery of tunnel driving was convincingly increased compared with the wait-list reference group. PMID:19440895

  18. Treatment of tunnel phobia: an experimental field study.

    PubMed

    Gotestam, K Gunnar; Svebak, Sven

    2009-01-01

    The opening of the deepest undersea tunnel in the world (264 m below sea level, 5600 m in length) replaced the ferry from the island of Hitra to the mainland in Norway. This event provoked phobic anxiety for traveling through the undersea tunnel in a number of individuals in the area. A treatment program for tunnel phobia was designed to test whether such a phobia could be mitigated by procedures previously proven effective in the treatment of other phobias. The program was presented to 18 persons with a specific phobia for tunnels and included a general discussion on the construction of undersea tunnels, given by an engineer from the tunnel construction company, and on phobic anxiety. It further consisted of gradual exposure to the tunnel in situ. Treatment effects were strong. All patients were able to travel on their own by car through the tunnel after the treatment. Their somatic complaints and phobic thoughts related to the tunnel were substantially reduced, and their mastery of tunnel driving was convincingly increased compared with the wait-list reference group.

  19. 7 x 10-Foot Atmospheric Wind Tunnel (AWT)

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Drawing of 7 x 10-Foot Atmospheric Wind Tunnel (AWT). In 1928, the NACA decided to replace its original Atmospheric Wind Tunnel (AWT #1) with two tunnels--the 5-foot vertical tunnel and a 7 by 10 foot rectangular throat tunnel. Both were open-throat, closed-return-passage tunnels. While the 5-foot vertical tunnel was to be used mainly for spin tests, the 7x10 was an all-purpose tunnel although the main intent was to study stability and control problems. Construction was completed in the summer of 1930; calibration later that same year. The balance was installed and the tunnel went into operation in early 1931. The Warwick Machine Co. of Newport News, Virginia had the contract to fabricate and erection the 7x10-Foot tunnel for a total cost of $18,018.90. The balance was made by Fairbanks, Morse and Co., of Baltimore, Maryland for 2,544.00. The honeycomb was made by the Berkley Machine Works and Foundry Co., Inc. of Norfolk, Virginia for $1,580 and the control panel by Clark Controller Co. of Cleveland, OH for $1,153.

  20. Distribution of tunnelling times for quantum electron transport

    NASA Astrophysics Data System (ADS)

    Rudge, Samuel L.; Kosov, Daniel S.

    2016-03-01

    In electron transport, the tunnelling time is the time taken for an electron to tunnel out of a system after it has tunnelled in. We define the tunnelling time distribution for quantum processes in a dissipative environment and develop a practical approach for calculating it, where the environment is described by the general Markovian master equation. We illustrate the theory by using the rate equation to compute the tunnelling time distribution for electron transport through a molecular junction. The tunnelling time distribution is exponential, which indicates that Markovian quantum tunnelling is a Poissonian statistical process. The tunnelling time distribution is used not only to study the quantum statistics of tunnelling along the average electric current but also to analyse extreme quantum events where an electron jumps against the applied voltage bias. The average tunnelling time shows distinctly different temperature dependence for p- and n-type molecular junctions and therefore provides a sensitive tool to probe the alignment of molecular orbitals relative to the electrode Fermi energy.