WorldWideScience

Sample records for shock tunnel studies

  1. Shock Tunnel Studies of Scramjet Phenomena 1993

    Science.gov (United States)

    Stalker, R. J.; Bakos, R. J.; Morgan, R. G.; Porter, L.; Mee, D.; Paull, A.; Tuttle, S.; Simmons, J. M.; Wendt, M.; Skinner, K.

    1995-01-01

    Reports by the staff of the University of Queensland on various research studies related to the advancement of scramjet technology and hypervelocity pulse test facilities are presented. These reports document the tests conducted in the reflected shock tunnel T4 and supporting research facilities that have been used to study the injection, mixing, and combustion of hydrogen fuel in generic scramjets at flow conditions typical of hypersonic flight. In addition, topics include the development of instrumentation and measurement technology, such as combustor wall shear and stream composition in pulse facilities, and numerical studies and analyses of the scramjet combustor process and the test facility operation. This research activity is Supplement 10 under NASA Grant NAGw-674.

  2. Shock Tunnel Studies of the Hypersonic Flowfield around the Hypervelocity Ballistic Models with Aerospikes

    Science.gov (United States)

    Balakalyani, G.; Saravanan, S.; Jagadeesh, G.

    Reduced drag and aerodynamic heating are the two basic design requirements for any hypersonic vehicle [1]. The flowfield around an axisymmetric blunt body is characterized by a bow shockwave standing ahead of its nose. The pressure and temperature behind this shock wave are very high. This increased pressure and temperature are responsible for the high levels of drag and aerodynamic heating over the body. In the past, there have been many investigations on the use of aerospikes as a drag reduction tool. These studies on spiked bodies aim at reducing both the drag and aerodynamic heating by modifying the hypersonic flowfield ahead of the nose of the body [2]. However, most of them used very simple configurations to experimentally study the drag reduction using spikes at hypersonic speeds [3] and therefore very little experimental data is available for a realistic geometric configuration. In the present study, the standard AGARD Hypervelocity Ballistic model 1 is used as the test model. The addition of the spike to the blunt body significantly alters the flowfield ahead of the nose, leading to the formation of a low pressure conical recirculation region, thus causing a reduction in drag and wall heat flux [4]. In the present investigation, aerodynamic drag force is measured over the Hypervelocity Ballistic model-1, with and without spike, at a flow enthalpy of 1.7 MJ/kg. The experiments are carried out at a Mach number of 8 and at zero angle of attack. An internally mountable accelerometer based 3-component force balance system is used to measure the aerodynamic forces on the model. Also computational studies are carried out to complement the experiments.

  3. New generation of free-piston shock tunnels

    Science.gov (United States)

    Morrison, W. R. B.; Stalker, R. J.; Duffin, J.

    1990-01-01

    Consideration is given to three free-piston driven hypersonic tunnels under construction that will greatly enhance existing test capabilities. The tunnel being built at Caltech will feature energy capabilities about 40 percent higher than those of the world's largest operational free-piston tunnel to date. The second tunnel under construction will allow full-size engine hardware at near-orbital speeds. The third facility is a high-performance expansion tube that will be capable of generating high enthalpy flows at speeds of up to 9 km/sec. It will provide flows with dissociation levels much lower than are attainable with a reflected shock tunnel, approaching actual flight conditions. A table shows the tunnels' characteristics.

  4. NO PLIF imaging in the CUBRC 48-inch shock tunnel

    Science.gov (United States)

    Jiang, N.; Bruzzese, J.; Patton, R.; Sutton, J.; Yentsch, R.; Gaitonde, D. V.; Lempert, W. R.; Miller, J. D.; Meyer, T. R.; Parker, R.; Wadham, T.; Holden, M.; Danehy, P. M.

    2012-12-01

    Nitric oxide planar laser-induced fluorescence (NO PLIF) imaging is demonstrated at a 10-kHz repetition rate in the Calspan University at Buffalo Research Center's (CUBRC) 48-inch Mach 9 hypervelocity shock tunnel using a pulse burst laser-based high frame rate imaging system. Sequences of up to ten images are obtained internal to a supersonic combustor model, located within the shock tunnel, during a single ~10-millisecond duration run of the ground test facility. Comparison with a CFD simulation shows good overall qualitative agreement in the jet penetration and spreading observed with an average of forty individual PLIF images obtained during several facility runs.

  5. Transient and steady-state flows in shock tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Hannemann, K. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Goettingen (Germany); Jacobs, P.A. [Queensland Univ., Brisbane (Australia). Dept. of Mechanical Engineering; Thomas, A.; McIntyre, T.J. [Queensland Univ., Brisbane, QLD. (Australia). Dept. of Physics

    1999-12-01

    Due to the difficulty of measuring all necessary flow quantities in the nozzle reservoir and the test section of high enthalpy shock tunnels, indirect computational methods are necessary to estimate the required flow parameters. In addition to steady state flow computations of the nozzle flow and the flow past wind tunnel models it is necessary to investigate the transient flow in the facility in order to achieve a better understanding of its performance. These transient effects include the nozzle starting flow, the interaction of the shock tube boundary layers and the reflected shock, thermal losses in the shock reflection region and the developing boundary layers in the expanding section of the nozzle. Additionally, the nonequilibrium chemical and thermal relaxation models which are used to compute high enthalpy flows have to be validated with appropriate experimental data. (orig.)

  6. Transient and steady-state flows in shock tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Hannemann, K. (Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Goettingen (Germany)); Jacobs, P.A. (Queensland Univ., Brisbane (Australia). Dept. of Mechanical Engineering); Thomas, A.; McIntyre, T.J. (Queensland Univ., Brisbane, QLD. (Australia). Dept. of Physics)

    1999-01-01

    Due to the difficulty of measuring all necessary flow quantities in the nozzle reservoir and the test section of high enthalpy shock tunnels, indirect computational methods are necessary to estimate the required flow parameters. In addition to steady state flow computations of the nozzle flow and the flow past wind tunnel models it is necessary to investigate the transient flow in the facility in order to achieve a better understanding of its performance. These transient effects include the nozzle starting flow, the interaction of the shock tube boundary layers and the reflected shock, thermal losses in the shock reflection region and the developing boundary layers in the expanding section of the nozzle. Additionally, the nonequilibrium chemical and thermal relaxation models which are used to compute high enthalpy flows have to be validated with appropriate experimental data. (orig.)

  7. NO PLIF imaging in the CUBRC 48-inch shock tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, N.; Bruzzese, J.; Patton, R.; Sutton, J.; Yentsch, R.; Gaitonde, D.V.; Lempert, W.R. [The Ohio State University, Departments of Mechanical and Aerospace Engineering, Columbus, OH (United States); Miller, J.D.; Meyer, T.R. [Iowa State University, Department of Mechanical Engineering, Ames, IA (United States); Parker, R.; Wadham, T.; Holden, M. [CUBRC, Buffalo, NY (United States); Danehy, P.M. [NASA Langley Research Center, Hampton, VA (United States)

    2012-12-15

    Nitric oxide planar laser-induced fluorescence (NO PLIF) imaging is demonstrated at a 10-kHz repetition rate in the Calspan University at Buffalo Research Center's (CUBRC) 48-inch Mach 9 hypervelocity shock tunnel using a pulse burst laser-based high frame rate imaging system. Sequences of up to ten images are obtained internal to a supersonic combustor model, located within the shock tunnel, during a single {proportional_to}10-millisecond duration run of the ground test facility. Comparison with a CFD simulation shows good overall qualitative agreement in the jet penetration and spreading observed with an average of forty individual PLIF images obtained during several facility runs. (orig.)

  8. NO PLIF Imaging in the CUBRC 48 Inch Shock Tunnel

    Science.gov (United States)

    Jiang, N.; Bruzzese, J.; Patton, R.; Sutton J.; Lempert W.; Miller, J. D.; Meyer, T. R.; Parker, R.; Wadham, T.; Holden, M.; hide

    2011-01-01

    Nitric Oxide Planar Laser-Induced Fluorescence (NO PLIF) imaging is demonstrated at a 10 kHz repetition rate in the Calspan-University at Buffalo Research Center s (CUBRC) 48-inch Mach 9 hypervelocity shock tunnel using a pulse burst laser-based high frame rate imaging system. Sequences of up to ten images are obtained internal to a supersonic combustor model, located within the shock tunnel, during a single approx.10-millisecond duration run of the ground test facility. This represents over an order of magnitude improvement in data rate from previous PLIF-based diagnostic approaches. Comparison with a preliminary CFD simulation shows good overall qualitative agreement between the prediction of the mean NO density field and the observed PLIF image intensity, averaged over forty individual images obtained during several facility runs.

  9. New Hypersonic Shock Tunnel at the Laboratory of Aerothermodynamics and Hypersonics Prof. Henry T. Nagamatsu

    International Nuclear Information System (INIS)

    Toro, P. G. P.; Minucci, M. A. S.; Chanes, J. B. Jr; Oliveira, A. C.; Gomes, F. A. A.; Myrabo, L. N.; Nagamatsu, Henry T.

    2008-01-01

    The new 0.60-m. nozzle exit diameter hypersonic shock tunnel was designed to study advanced air-breathing propulsion system such as supersonic combustion and/or laser technologies. In addition, it may be used for hypersonic flow studies and investigations of the electromagnetic (laser) energy addition for flow control. This new hypersonic shock tunnel was designed and installed at the Laboratory for of Aerothermodynamics and Hypersonics Prof. Henry T. Nagamatsu, IEAv-CTA, Brazil. The design of the tunnel enables relatively long test times, 2-10 milliseconds, suitable for the experiments performed at the laboratory. Free stream Mach numbers ranging from 6 to 25 can be produced and stagnation pressures and temperatures up to 360 atm. and up to 9,000 K, respectively, can be generated. Shadowgraph and schlieren optical techniques will be used for flow visualization

  10. LIGS measurements in the nozzle reservoir of a free-piston shock tunnel

    Science.gov (United States)

    Altenhöfer, P.; Sander, T.; Koroll, F.; Mundt, Ch.

    2018-02-01

    Free-piston shock tunnels are ground-based test facilities allowing the simulation of reentry flow conditions in a simple and cost-efficient way. For a better understanding of the processes occurring in a shock tunnel as well as for an optimal comparability of experimental data gained in shock tunnels to numerical simulations, it is highly desirable to have the best possible characterization of the generated test gas flows. This paper describes the final step of the development of a laser-induced grating spectroscopy (LIGS) system capable of measuring the temperature in the nozzle reservoir of a free-piston shock tunnel during tests: the successful adaptation of the measurement system to the shock tunnel. Preliminary measurements were taken with a high-speed camera and a LED lamp in order to investigate the optical transmissibility of the measurement volume during tests. The results helped to successfully measure LIGS signals in shock tube mode and shock tunnel mode in dry air seeded with NO. For the shock tube mode, six successful measurements for a shock Mach number of about 2.35 were taken in total, two of them behind the incoming shock (p ≈ 1 MPa, T ≈ 600 K) and four after the passing of the reflected shock (p ≈ 4 MPa, T ≈ 1000 K). For five of the six measurements, the derived temperatures were within a deviation range of 6% to a reference value calculated from measured shock speed. The uncertainty estimated was less than or equal to 3.5% for all six measurements. Two LIGS signals from measurements behind the reflected shock in shock tunnel mode were analyzed in detail. One of the signals allowed an unambiguous derivation of the temperature under the conditions of a shock with Mach 2.7 (p ≈ 5 MPa, T ≈ 1200 K, deviation 0.5% , uncertainty 4.9% ).

  11. Shock tunnel measurements of surface pressures in shock induced separated flow field using MEMS sensor array

    International Nuclear Information System (INIS)

    Sriram, R; Jagadeesh, G; Ram, S N; Hegde, G M; Nayak, M M

    2015-01-01

    Characterized not just by high Mach numbers, but also high flow total enthalpies—often accompanied by dissociation and ionization of flowing gas itself—the experimental simulation of hypersonic flows requires impulse facilities like shock tunnels. However, shock tunnel simulation imposes challenges and restrictions on the flow diagnostics, not just because of the possible extreme flow conditions, but also the short run times—typically around 1 ms. The development, calibration and application of fast response MEMS sensors for surface pressure measurements in IISc hypersonic shock tunnel HST-2, with a typical test time of 600 μs, for the complex flow field of strong (impinging) shock boundary layer interaction with separation close to the leading edge, is delineated in this paper. For Mach numbers 5.96 (total enthalpy 1.3 MJ kg −1 ) and 8.67 (total enthalpy 1.6 MJ kg −1 ), surface pressures ranging from around 200 Pa to 50 000 Pa, in various regions of the flow field, are measured using the MEMS sensors. The measurements are found to compare well with the measurements using commercial sensors. It was possible to resolve important regions of the flow field involving significant spatial gradients of pressure, with a resolution of 5 data points within 12 mm in each MEMS array, which cannot be achieved with the other commercial sensors. In particular, MEMS sensors enabled the measurement of separation pressure (at Mach 8.67) near the leading edge and the sharply varying pressure in the reattachment zone. (paper)

  12. Shock-tunnel combustor testing for hypersonic vehicles

    Science.gov (United States)

    Loomis, Mark P.

    1994-01-01

    Proposed configurations for the next generation of transatmospheric vehicles will rely on air breathing propulsion systems during all or part of their mission. At flight Mach numbers greater than about 7 these engines will operate in the supersonic combustion ramjet mode (scramjet). Ground testing of these engine concepts above Mach 8 requires high pressure, high enthalpy facilities such as shock tunnels and expansion tubes. These impulse, or short duration facilities have test times on the order of a millisecond, requiring high speed instrumentation and data systems. One such facility ideally suited for scramjet testing is the NASA-Ames 16-Inch shock tunnel, which over the last two years has completed a series of tests for the NASP (National Aero-Space Plane) program at simulated flight Mach numbers ranging from 12-16. The focus of the experimental programs consisted of a series of classified tests involving a near-full scale hydrogen fueled scramjet combustor model in the semi-free jet method of engine testing whereby the compressed forebody flow ahead of the cowl inlet is reproduced (see appendix A). The AIMHYE-1 (Ames Integrated Modular Hypersonic Engine) test entry for the NASP program was completed in April 1993, while AIMHYE-2 was completed in May 1994. The test entries were regarded as successful, resulting in some of the first data of its kind on the performance of a near full scale scramjet engine at Mach 12-16. The data was distributed to NASP team members for use in design system verification and development. Due to the classified nature of the hardware and data, the data reports resulting from this work are classified and have been published as part of the NASP literature. However, an unclassified AIAA paper resulted from the work and has been included as appendix A. It contains an overview of the test program and a description of some of the important issues.

  13. Numerical simulation of nonequilibrium flow in high-enthalpy shock tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, M.; Men' shov, I.; Nakamura, Y

    2005-03-01

    The flow field of a nozzle starting process with thermal and chemical nonequilibrium has been simulated. This flow is produced in high enthalpy impulse facilities such as the free piston shock tunnel. The governing equations are the axisymmetric, compressible Navier-Stokes equations. In this study, Park's two-temperature model, where air consists of five species, is used for defining the thermodynamic properties of air as a driven gas. The numerical scheme employed here is the hybrid scheme of the explicit and implicit methods, which was developed in our laboratory, along with AUSM{sup +} to evaluate inviscid fluxes. In the present simulation, the Mach number of an incident shock wave is set at M{sub s}=10.0. It corresponds to a specific enthalpy, h{sub 0}, of 12 MJ/kg. The results clearly show the complicated thermal and chemical nonequilibrium flow field around the end of the shock tube section and at the nozzle inlet during the initial stage of the nozzle starting process. They also suggest that the phenomenon of nozzle melting might be associated with a flow separation at the nozzle inlet.

  14. Large carbon cluster thin film gauges for measuring aerodynamic heat transfer rates in hypersonic shock tunnels

    International Nuclear Information System (INIS)

    Srinath, S; Reddy, K P J

    2015-01-01

    Different types of Large Carbon Cluster (LCC) layers are synthesized by a single-step pyrolysis technique at various ratios of precursor mixture. The aim is to develop a fast responsive and stable thermal gauge based on a LCC layer which has relatively good electrical conduction in order to use it in the hypersonic flow field. The thermoelectric property of the LCC layer has been studied. It is found that these carbon clusters are sensitive to temperature changes. Therefore suitable thermal gauges were developed for blunt cone bodies and were tested in hypersonic shock tunnels at a flow Mach number of 6.8 to measure aerodynamic heating. The LCC layer of this thermal gauge encounters high shear forces and a hostile environment for test duration in the range of a millisecond. The results are favorable to use large carbon clusters as a better sensor than a conventional platinum thin film gauge in view of fast responsiveness and stability. (paper)

  15. Acoustic waves in shock tunnels and expansion tubes

    Science.gov (United States)

    Paull, A.; Stalker, R. J.

    1992-01-01

    It is shown that disturbances in shock and expansion tubes can be modelled as lateral acoustic waves. The ratio of sound speed across the driver-test gas interface is shown to govern the quantity of noise in the test gas. Frequency 'focusing' which is fundamental to centered unsteady expansions is discussed and displayed in centerline pitot pressure measurements.

  16. Performance data of the new free-piston shock tunnel T5 at GALCIT

    Science.gov (United States)

    Hornung, H.; Sturtevant, B.; Belanger, J.; Sanderson, S.; Brouillette, M.; Jenkins, M.

    1992-01-01

    A new free piston shock tunnel has been constructed at the Graduate Aeronautical Laboratories at Caltec. Compression tube length is 30 m and diameter 300 mm. Shock tube length is 12 m and diameter 90 mm. Piston mass is 150 kg and maximum diaphragm burst pressure is 130 MPa. Special features of this facility are that the pressure in the driver gas is monitored throughout the compression process until well after diaphragm rupture, and that the diaphragm burst pressure can be measured dynamically. An analysis of initial performance data including transient behavior of the flow over models is presented.

  17. Reactivation of the Shock-Tunnel Facility at Fort Cronkhite. Final report

    International Nuclear Information System (INIS)

    1982-05-01

    This final report describes the results of work undertaken to reactivate the Shock Tunnel Facility at Battery Townsley, Fort Cronkhite, Marin County, California. The facility has been reactivated and can not be utilized for blast testing. The major emphasis will be testing of concepts pertaining to programs of interest to the Federal Emergency Management Agency (FEMA) and in particular to civil defense oriented research. However, a wide variety of testing requirements can be accommodated. For example, past programs at the facility have included: tests of debris from trees subjected to blast for Bell Telephone Laboratories; tests of the response of aluminum hull panels to blast loading and of the response of a model surface effects ship for the Naval Ship Research and Development center, and tests of the response of a radome prototype to blast loading conducted for ANCOM (the radome manufacturer). The Shock Tunnel Facility is located in a former coastal defense 16-inch gun emplacement constructed by the US Army beginning in 1938. It was converted in 1967 to serve as a facility for full-scale testing of the loading and response of structural elements and civil defense equipment. It remained in operation until November 1976 when Battery Townsley was turned over to the National Park Service. Work under the present purchase order consisted of the following major tasks: (I) cleanup and secure the facility, (II) reactivate the shock tunnel, and (III) design permanent facility improvements

  18. Mass spectrometric measurements of driver gas arrival in the T4 free-piston shock-tunnel

    Science.gov (United States)

    Boyce, R. R.; Takahashi, M.; Stalker, R. J.

    2005-12-01

    Available test time is an important issue for ground-based flow research, particularly for impulse facilities such as shock tunnels, where test times of the order of several ms are typical. The early contamination of the test flow by the driver gas in such tunnels restricts the test time. This paper reports measurements of the driver gas arrival time in the test section of the T4 free-piston shock-tunnel over the total enthalpy range 3 17 MJ/kg, using a time-of-flight mass spectrometer. The results confirm measurements made by previous investigators using a choked duct driver gas detector at these conditions, and extend the range of previous mass spectrometer measurements to that of 3 20 MJ/kg. Comparisons of the contamination behaviour of various piston-driven reflected shock tunnels are also made.

  19. Evaluation of PNS-computed heating and hypersonic shock tunnel data on sharp and inclined blunt cones

    International Nuclear Information System (INIS)

    Hudson, M.L.

    1988-01-01

    As part of the ongoing development and verification of the Parabolized Navier-Stokes (PNS) technique, computed heat transfer rates have been compared with recently acquired experimental data. The flow fields were computer for laminar and turbulent flow over sharp, blunt tripped sphere-cones at 0/degree/ to 20/degree/ angle of attack in a hypersonic shock tunnel flow at Mach numbers of 11, 13, and 16. Grid refinement studies were performed and minimum smoothing parameters were sought. The average percent difference between the measured mean heat transfer rate and the PNS-computed value was 12% for the sharp and blunt cones at 0/degree/ angle of attack. For the blunt cones at angle of attack, the average percent difference was 11% on the windward ray and 36% on the leeward ray. PNS-predicted flow physics such as boundary layer thickness, shock standoff distance, and crossflow separation were examined. 15 refs., 12 figs

  20. Flow establishment behind blunt bodies at hypersonic speeds in a shock tunnel

    Science.gov (United States)

    Park, G.; Hruschka, R.; Gai, S. L.; Neely, A. J.

    2008-11-01

    An investigation of flow establishment behind two blunt bodies, a circular cylinder and a 45° half-angle blunted-cone was conducted. Unlike previous studies which relied solely on surface measurements, the present study combines these with unique high-speed visualisation to image the establishment of the flow structure in the base region. Test flows were generated using a free-piston shock tunnel at a nominal Mach number of 10. The freestream unit Reynolds numbers considered were 3.02x105/m and 1.17x106/m at total enthalpies of 13.35MJ/kg and 3.94MJ/kg, respectively. In general, the experiments showed that it takes longer to establish steady heat flux than pressure. The circular cylinder data showed that the near wake had a slight Reynolds number effect, where the size of the near wake was smaller for the high enthalpy flow condition. The blunted-cone data showed that the heat flux and pressures reached steady states in the near wake at similar times for both high and low enthalpy conditions.

  1. Modelling the complete operation of a free-piston shock tunnel for a low enthalpy condition

    Science.gov (United States)

    McGilvray, M.; Dann, A. G.; Jacobs, P. A.

    2013-07-01

    Only a limited number of free-stream flow properties can be measured in hypersonic impulse facilities at the nozzle exit. This poses challenges for experimenters when subsequently analysing experimental data obtained from these facilities. Typically in a reflected shock tunnel, a simple analysis that requires small amounts of computational resources is used to calculate quasi-steady gas properties. This simple analysis requires initial fill conditions and experimental measurements in analytical calculations of each major flow process, using forward coupling with minor corrections to include processes that are not directly modeled. However, this simplistic approach leads to an unknown level of discrepancy to the true flow properties. To explore the simple modelling techniques accuracy, this paper details the use of transient one and two-dimensional numerical simulations of a complete facility to obtain more refined free-stream flow properties from a free-piston reflected shock tunnel operating at low-enthalpy conditions. These calculations were verified by comparison to experimental data obtained from the facility. For the condition and facility investigated, the test conditions at nozzle exit produced with the simple modelling technique agree with the time and space averaged results from the complete facility calculations to within the accuracy of the experimental measurements.

  2. Studying shocks in model astrophysical flows

    International Nuclear Information System (INIS)

    Chakrabarti, S.K.

    1989-01-01

    We briefly discuss some properties of the shocks in the existing models for quasi two-dimensional astrophysical flows. All of these models which allow the study of shock analytically have some unphysical characteristics due to inherent assumptions made. We propose a hybrid model for a thin flow which has fewer unpleasant features and is suitable for the study of shocks. (author). 5 refs

  3. Performance data of the new free-piston shock tunnel at GALCIT

    Science.gov (United States)

    Hornung, Hans G.

    1992-01-01

    The new free-piston shock tunnel has been partially calibrated, and a range of operating conditions has been found. A large number of difficulties were encountered during the shake-down period, of which the ablation of various parts was the most severe. Solutions to these problems were found. The general principles of high-enthalpy simulation are outlined, and the parameter space covered by T5 is given. Examples of the operating data show that, with care, excellent repeatability may be obtained. The temporal uniformity of the reservoir pressure is very good, even at high enthalpy, because it is possible to operate at tailored-interface and tuned-piston conditions over the whole enthalpy range. Examples of heat transfer and Pitot-pressure measurements are also presented.

  4. Fluorescence Imaging of Rotational and Vibrational Temperature in a Shock Tunnel Nozzle Flow

    Science.gov (United States)

    Palma, Philip C.; Danehy, Paul M.; Houwing, A. F. P.

    2003-01-01

    Two-dimensional rotational and vibrational temperature measurements were made at the nozzle exit of a free-piston shock tunnel using planar laser-induced fluorescence. The Mach 7 flow consisted predominantly of nitrogen with a trace quantity of nitric oxide. Nitric oxide was employed as the probe species and was excited at 225 nm. Nonuniformities in the distribution of nitric oxide in the test gas were observed and were concluded to be due to contamination of the test gas by driver gas or cold test gas.The nozzle-exit rotational temperature was measured and is in reasonable agreement with computational modeling. Nonlinearities in the detection system were responsible for systematic errors in the measurements. The vibrational temperature was measured to be constant with distance from the nozzle exit, indicating it had frozen during the nozzle expansion.

  5. Exploratory laser-driven shock wave studies

    International Nuclear Information System (INIS)

    Solem, J.C.; Veeser, L.R.

    1977-11-01

    We show the results of a feasibility study for investigating shock structure and for measuring equation-of-state parameters using high-energy, short-pulse lasers. We discuss the temporal and spatial structure of the luminosity from laser-driven shock unloading in aluminum foils. We demonstrate that shock velocity can be measured by observing the time interval between shock emergence across two thicknesses and show data for shocks of 1.3 and 2.1 Mbar. The fact that we observe shock fronts cleanly breaking through steps as small as 3 μm indicates that the shock front thickness is very small in the few megabar region; this is the first experimental verification that these fronts are not more than a few micrometers thick. We present approximate measurements of free-surface velocity. Finally, we speculate on the use of these techniques to obtain detailed equation-of-state data

  6. Variability in ACL tunnel placement: observational clinical study of surgeon ACL tunnel variability.

    Science.gov (United States)

    Wolf, Brian R; Ramme, Austin J; Wright, Rick W; Brophy, Robert H; McCarty, Eric C; Vidal, Armando R; Parker, Richard D; Andrish, Jack T; Amendola, Annunziato

    2013-06-01

    Multicenter and multisurgeon cohort studies on anterior cruciate ligament (ACL) reconstruction are becoming more common. Minimal information exists on intersurgeon and intrasurgeon variability in ACL tunnel placement. Purpose/ The purpose of this study was to analyze intersurgeon and intrasurgeon variability in ACL tunnel placement in a series of The Multicenter Orthopaedic Outcomes Network (MOON) ACL reconstruction patients and in a clinical cohort of ACL reconstruction patients. The hypothesis was that there would be minimal variability between surgeons in ACL tunnel placement. Cross-sectional study; Level of evidence, 3. Seventy-eight patients who underwent ACL reconstruction by 8 surgeons had postoperative imaging with computed tomography, and ACL tunnel location and angulation were analyzed using 3-dimensional surface processing and measurement. Intersurgeon and intrasurgeon variability in ACL tunnel placement was analyzed. For intersurgeon variability, the range in mean ACL femoral tunnel depth between surgeons was 22%. For femoral tunnel height, there was a 19% range. Tibial tunnel location from anterior to posterior on the plateau had a 16% range in mean results. There was only a small range of 4% for mean tibial tunnel location from the medial to lateral dimension. For intrasurgeon variability, femoral tunnel depth demonstrated the largest ranges, and tibial tunnel location from medial to lateral on the plateau demonstrated the least variability. Overall, surgeons were relatively consistent within their own cases. Using applied measurement criteria, 85% of femoral tunnels and 90% of tibial tunnels fell within applied literature-based guidelines. Ninety-one percent of the axes of the femoral tunnels fell within the boundaries of the femoral footprint. The data demonstrate that surgeons performing ACL reconstructions are relatively consistent between each other. There is, however, variability of average tunnel placement up to 22% of mean condylar depth

  7. A study for the KAERI research tunnel

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-01

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

  8. Study of Scanning Tunneling Microscope control electronics

    International Nuclear Information System (INIS)

    Oliva, A.J.; Pancarobo, M.; Denisenko, N.; Aguilar, M.; Rejon, V.; Pena, J.L.

    1994-01-01

    A theoretical study of Scanning Tunneling Microscope control electronics is made. The knowledge of its behaviour allows us to determine accurately the region where the unstable operation could effect the measurements, and also to set the optimal working parameters. Each feedback circuitry compound is discussed as well as their mutual interaction. Different working conditions analysis and results are presented. (Author) 12 refs

  9. Study on Reflected Shock Wave/Boundary Layer Interaction in a Shock Tube

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Wook; Kim, Tae Ho; Kim, Heuy Dong [Andong Nat’l Univ., Andong (Korea, Republic of)

    2017-07-15

    The interaction between a shock wave and a boundary layer causes boundary layer separation, shock train, and in some cases, strong unsteadiness in the flow field. Such a situation is also observed in a shock tube, where the reflected shock wave interacts with the unsteady boundary layer. However, only a few studies have been conducted to investigate the shock train phenomenon in a shock tube. In the present study, numerical studies were conducted using the two-dimensional axisymmetric domain of a shock tube, and compressible Navier-Stokes equations were solved to clarify the flow characteristics of shock train phenomenon inside a shock tube. A detailed wave diagram was developed based on the present computational results, which were validated with existing experimental data.

  10. ZEDEX - A study of damage and disturbance from tunnel excavation by blasting and tunnel boring

    International Nuclear Information System (INIS)

    Emsley, S.; Olsson, Olle; Stenberg, L.; Alheid, H.J.; Falls, S.

    1997-12-01

    The objectives of the ZEDEX project were to understand the mechanical behaviour of the excavation disturbed zone (EDZ) with respect to its origin, character, magnitude of property change, extent and its dependence on excavation method. Excavation with normal smooth blasting, blasting with low shock explosives and tunnel boring were studied. The drifts are located at Aespoe at a depth of 420 m, the profiles are circular and 5 m in diameter. The results have shown that there is a damaged zone, close to the drift wall dominated by changes in rock properties which are irreversible, and that there is a disturbed zone beyond the damaged zone that is dominated by changes in stress state and mainly reversible. There is no distinct boundary between the two zones. The results from ZEDEX indicate that the role of the EDZ as a preferential pathway to radionuclide transport is limited to the damaged zone. The extent of the damaged zone can be limited through application of appropriate excavation methods. By limiting the extent of the damaged zone it should also be feasible to block pathways in the damaged zone by plugs placed at strategic locations

  11. ZEDEX - A study of damage and disturbance from tunnel excavation by blasting and tunnel boring

    Energy Technology Data Exchange (ETDEWEB)

    Emsley, S [Golder Associates, Maidenhead (United Kingdom); Olsson, Olle; Stenberg, L [Swedish Nuclear Fuel and Waste Co., Figeholm (Sweden); Alheid, H J [Federal Inst. for Geosciences and Natural Resources, Hannover (Germany); Falls, S [Queens Univ., Kingston, ON (Canada)

    1997-12-01

    The objectives of the ZEDEX project were to understand the mechanical behaviour of the excavation disturbed zone (EDZ) with respect to its origin, character, magnitude of property change, extent and its dependence on excavation method. Excavation with normal smooth blasting, blasting with low shock explosives and tunnel boring were studied. The drifts are located at Aespoe at a depth of 420 m, the profiles are circular and 5 m in diameter. The results have shown that there is a damaged zone, close to the drift wall dominated by changes in rock properties which are irreversible, and that there is a disturbed zone beyond the damaged zone that is dominated by changes in stress state and mainly reversible. There is no distinct boundary between the two zones. The results from ZEDEX indicate that the role of the EDZ as a preferential pathway to radionuclide transport is limited to the damaged zone. The extent of the damaged zone can be limited through application of appropriate excavation methods. By limiting the extent of the damaged zone it should also be feasible to block pathways in the damaged zone by plugs placed at strategic locations 68 refs, 92 figs, 31 tabs

  12. Tunnel Boring Machine Performance Study. Final Report

    Science.gov (United States)

    1984-06-01

    Full face tunnel boring machine "TBM" performance during the excavation of 6 tunnels in sedimentary rock is considered in terms of utilization, penetration rates and cutter wear. The construction records are analyzed and the results are used to inves...

  13. Aeroheating Measurement of Apollo Shaped Capsule with Boundary Layer Trip in the Free-piston Shock Tunnel HIEST

    Science.gov (United States)

    Hideyuki, TANNO; Tomoyuki, KOMURO; Kazuo, SATO; Katsuhiro, ITOH; Lillard, Randolph P.; Olejniczak, Joseph

    2013-01-01

    An aeroheating measurement test campaign of an Apollo capsule model with laminar and turbulent boundary layer was performed in the free-piston shock tunnel HIEST at JAXA Kakuda Space Center. A 250mm-diameter 6.4%-scaled Apollo CM capsule model made of SUS-304 stainless steel was applied in this study. To measure heat flux distribution, the model was equipped with 88 miniature co-axial Chromel-Constantan thermocouples on the heat shield surface of the model. In order to promote boundary layer transition, a boundary layer trip insert with 13 "pizza-box" isolated roughness elements, which have 1.27mm square, were placed at 17mm below of the model geometric center. Three boundary layer trip inserts with roughness height of k=0.3mm, 0.6mm and 0.8mm were used to identify the appropriate height to induce transition. Heat flux records with or without roughness elements were obtained for model angles of attack 28º under stagnation enthalpy between H(sub 0)=3.5MJ/kg to 21MJ/kg and stagnation pressure between P(sub 0)=14MPa to 60MPa. Under the condition above, Reynolds number based on the model diameter was varied from 0.2 to 1.3 million. With roughness elements, boundary layer became fully turbulent less than H(sub 0)=9MJ/kg condition. However, boundary layer was still laminar over H(sub 0)=13MJ/kg condition even with the highest roughness elements. An additional experiment was also performed to correct unexpected heat flux augmentation observed over H(sub 0)=9MJ/kg condition.

  14. Fire safety case study of a railway tunnel: Smoke evacuation

    Directory of Open Access Journals (Sweden)

    van Maele Karim

    2007-01-01

    Full Text Available When a fire occurs in a tunnel, it is of great importance to assure the safety of the occupants of the tunnel. This is achieved by creating smoke-free spaces in the tunnel through control of the smoke gases. In this paper, results are presented of a study concerning the fire safety in a real scale railway tunnel test case. Numerical simulations are performed in order to examine the possibility of natural ventilation of smoke in inclined tunnels. Several aspects are taken into account: the length of the simulated tunnel section, the slope of the tunnel and the possible effects of external wind at one portal of the tunnel. The Fire Dynamics Simulator of the National Institute of Standards and Technology, USA, is applied to perform the simulations. The simulations show that for the local behavior of the smoke during the early stages of the fire, the slope of the tunnel is of little importance. Secondly, the results show that external wind and/or pressure conditions have a large effect on the smoke gases inside the tunnel. Finally, some idea for the value of the critical ventilation velocity is given. The study also shows that computational fluid dynamics calculations are a valuable tool for large scale, real life complex fire cases. .

  15. Effect of Surface Blasting on Subway Tunnels- A Parametric Study

    Directory of Open Access Journals (Sweden)

    Hossein Entezari Zarch

    2017-01-01

    Full Text Available During wars and crises, the underground tunnels are used as a safe space. Therefore, the stability and safety of them under a blast is of particular importance. In this paper, the Finite Difference Method has been used to study the influence of the change in geotechnical parameters and depth on surface blasting on subway tunnels. Results showed that increasing the internal friction angle, modulus of elasticity and cohesion of the soil reduced the effects of blast loads on the vertical displacement and bending moment in the center of tunnel crown. Furthermore, the results showed that increasing the depth of the tunnel reduced the effects of blast loading. Comparing all parameters collectively showed that the increase in the modulus of elasticity of the soil and depth of the tunnel is the most effective in reducing the influence of the blast loads on the vertical displacement and bending moment of the tunnel crown, respectively.

  16. Sediment and Cavitation Erosion Studies through Dam Tunnels

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2016-01-01

    Full Text Available This paper presents results of sediment and cavitation erosion through Tunnel 2 and Tunnel 3 of Tarbela Dam in Pakistan. Main bend and main branch of Tunnel 2 and outlet 1 and outlet 3 of Tunnel 3 are concluded to be critical for cavitation and sediment erosion. Studies are also performed for increased sediments flow rate, concluding 5 kg/sec as the critical value for sudden increase in erosion rate density. Erosion rate is concluded to be the function of sediment flow rate and head condition. Particulate mass presently observed is reasonably low, hence presently not affecting the velocity and the flow field.

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

    Directory of Open Access Journals (Sweden)

    Jinxing Lai

    2017-01-01

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

  18. The comparison between limited open carpal tunnel release using direct vision and tunneling technique and standard open carpal tunnel release: a randomized controlled trial study.

    Science.gov (United States)

    Suppaphol, Sorasak; Worathanarat, Patarawan; Kawinwongkovit, Viroj; Pittayawutwinit, Preecha

    2012-04-01

    To compare the operative outcome of carpal tunnel release between limited open carpal tunnel release using direct vision and tunneling technique (group A) with standard open carpal tunnel release (group B). Twenty-eight patients were enrolled in the present study. A single blind randomized control trial study was conducted to compare the postoperative results between group A and B. The study parameters were Levine's symptom severity and functional score, grip and pinch strength, and average two-point discrimination. The postoperative results between two groups were comparable with no statistical significance. Only grip strength at three months follow up was significantly greater in group A than in group B. The limited open carpal tunnel release in the present study is effective comparable to the standard open carpal tunnel release. The others advantage of this technique are better cosmesis and improvement in grip strength at the three months postoperative period.

  19. Shock-wave induced mechanoluminescence: A new technique for studying effects of shock pressure on crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, B.P.; Parganiha, S.; Sonwane, V.D. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh (India); Chandra, V.K. [Department of Electrical and Electronics Engineering, Chhatrapati Shivaji Institute of Technology, Shivaji Nagar, Kolihapuri, Durg 491001, Chhattisgarh (India); Jha, Piyush, E-mail: piyushjha22@rediffmail.com [Department of Applied Physics, Raipur Institute of Technology, Chhatauna, Mandir Hasuad, Raipur 492101, Chhattisgarh (India); Baghel, R.N. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh (India)

    2016-10-15

    The impact of a projectile propelled to velocities in the range of 0.5–2.5 km/s on to a target (X-cut quartz crystal) produces shock waves travelling at velocity of nearly 10 km/s in target, in which intense mechanoluminescence (ML) pulses of microsecond duration are produced, both in compression and post-compression conditions. The piezoelectric field produced due to surface charges of fractured target, causes band bending and subsequently, the free charge carriers are generated in the respective bands and the emission of ML occurs. The ML appears after a delay time t{sub th} whose value decreases with increasing value of the shock pressure. Initially, the ML intensity increases with the shock pressure because of the creation of more surfaces; however, for higher values of the shock pressure, the ML intensity tends to attain a saturation value because of the hardening of the crystals due to the creation of small crystallites in which the creation of new surfaces becomes difficult. The ratio between peak ML intensity in the uncompressed region and the maximum ML intensity in the compressed region decreases with increasing shock pressure because more defects produced at high pressure generate higher barrier for the relaxation of blocked cracks under compression. The expressions derived for characteristics of shock-induced ML are able to explain satisfactorily the experimental results. Shock-wave velocity, shock pressure, transit time, lifetime of electrons in conduction band, etc. can be determined by the shock-induced ML.As such, the shock-induced ML provides a new optical technique for the studies of materials under shock pressure.

  20. Surface physics studied by means of scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Besenbacher, F.; Laegsgaard, E.; Stensgaard, I.

    1993-01-01

    Scanning tunneling microscopy has been applied to study silicon crystal structures, oxygen on Cu (110), and real industrial catalyst surfaces. For the latter purpose an Atomic Force Microscope is being developed. (EG)

  1. EXPERIMENTAL STUDY OF SHOCK WAVE DYNAMICS IN MAGNETIZED PLASMAS

    International Nuclear Information System (INIS)

    Podder, Nirmol K.

    2009-01-01

    In this four-year project (including one-year extension), the project director and his research team built a shock-wave-plasma apparatus to study shock wave dynamics in glow discharge plasmas in nitrogen and argon at medium pressure (1-20 Torr), carried out various plasma and shock diagnostics and measurements that lead to increased understanding of the shock wave acceleration phenomena in plasmas. The measurements clearly show that in the steady-state dc glow discharge plasma, at fixed gas pressure the shock wave velocity increases, its amplitude decreases, and the shock wave disperses non-linearly as a function of the plasma current. In the pulsed discharge plasma, at fixed gas pressure the shock wave dispersion width and velocity increase as a function of the delay between the switch-on of the plasma and shock-launch. In the afterglow plasma, at fixed gas pressure the shock wave dispersion width and velocity decrease as a function of the delay between the plasma switch-off and shock-launch. These changes are found to be opposite and reversing towards the room temperature value which is the initial condition for plasma ignition case. The observed shock wave properties in both igniting and afterglow plasmas correlate well with the inferred temperature changes in the two plasmas

  2. Flash photolysis-shock tube studies

    Energy Technology Data Exchange (ETDEWEB)

    Michael, J.V. [Argonne National Laboratory, IL (United States)

    1993-12-01

    Even though this project in the past has concentrated on the measurement of thermal bimolecular reactions of atomic species with stable molecules by the flash or laser photolysis-shock tube (FP- or LP-ST) method using atomic resonance absorption spectrometry (ARAS) as the diagnostic technique, during the past year the authors have concentrated on studies of the thermal decompositions of selected chlorocarbon molecules. These studies are necessary if the degradation of chlorine containing organic molecules by incineration are to be understood at the molecular level. Clearly, destruction of these molecules will not only involve abstraction reactions, when possible, but also thermal decomposition followed by secondary reactions of the initially formed atoms and radicals. Studies on the thermal decomposition of CH{sub 3}Cl are complete, and the curve-of-growth for Cl-atom atomic resonance absorption has been determined. The new thermal decomposition studies are similar to those already reported for CH{sub 3}Cl.

  3. Water Tunnel Studies of Dynamic Wing Flap Effects

    Science.gov (United States)

    2016-06-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited WATER TUNNEL...Master’s Thesis 4. TITLE AND SUBTITLE WATER TUNNEL STUDIES OF DYNAMIC WING FLAP EFFECTS 5. FUNDING NUMBERS 6. AUTHOR(S) Edgar E. González 7. PERFORMING...ABSTRACT (maximum 200 words ) The flow features developing over a two-element NACA 0012 airfoil, with the rear portion serving as a trailing edge flap

  4. Mass spectrometric measurements of the freestream composition in the T4 free-piston shock-tunnel

    Science.gov (United States)

    Boyce, R. R.; Takahashi, M.; Stalker, R. J.

    2005-12-01

    The freestream composition is an important parameter in ground-based aerodynamic testing, and direct measurement of it is very important. This paper reports extensive composition measurements in the freestream of the T4 free-piston shock-tunnel, employing a recently improved time-of-flight mass spectrometer. A wide range of nozzle reservoir conditions were used. The results show good agreement between measured and theoretical values for nitric oxide over the entire enthalpy range reported (2.5 13 MJ/kg). This provides confidence that the chemistry model is correctly predicting sudden freezing of NO in the nozzle expansion. On the other hand, no monatomic species have been measured other than those produced by dissociative ionisation within the mass spectrometer, even at flow conditions where significant freestream dissociation is expected. Furthermore, excess diatomic oxygen is detected at high enthalpies. These observations are consistent with the possibility that oxygen recombination is not correctly predicted in the nozzle expansion, with sudden freezing occurring significantly later than predicted. However, the observations are also consistent with possible catalytic recombination in the skimmer system. The possibility for producing an empirical correlation between the freestream composition and the reservoir entropy has also been observed.

  5. Free-flight measurement technique in the free-piston high-enthalpy shock tunnel

    Science.gov (United States)

    Tanno, H.; Komuro, T.; Sato, K.; Fujita, K.; Laurence, S. J.

    2014-04-01

    A novel multi-component force-measurement technique has been developed and implemented at the impulse facility JAXA-HIEST, in which the test model is completely unrestrained during the test and thus experiences free-flight conditions for a period on the order of milliseconds. Advantages over conventional free-flight techniques include the complete absence of aerodynamic interference from a model support system and less variation in model position and attitude during the test itself. A miniature on-board data recorder, which was a key technology for this technique, was also developed in order to acquire and store the measured data. The technique was demonstrated in a HIEST wind-tunnel test campaign in which three-component aerodynamic force measurement was performed on a blunted cone of length 316 mm, total mass 19.75 kg, and moment of inertia 0.152 kgm2. During the test campaign, axial force, normal forces, and pitching moment coefficients were obtained at angles of attack from 14° to 32° under two conditions: H0 = 4 MJ/kg, P0 = 14 MPa; and H0 = 16 MJ/kg, P0 = 16 MPa. For the first, low-enthalpy condition, the test flow was considered a perfect gas; measurements were thus directly compared with those obtained in a conventional blow-down wind tunnel (JAXA-HWT2) to evaluate the accuracy of the technique. The second test condition was a high-enthalpy condition in which 85% of the oxygen molecules were expected to be dissociated; high-temperature real-gas effects were therefore evaluated by comparison with results obtained in perfect-gas conditions. The precision of the present measurements was evaluated through an uncertainty analysis, which showed the aerodynamic coefficients in the HIEST low enthalpy test agreeing well with those of JAXA-HWT2. The pitching-moment coefficient, however, showed significant differences between low- and high-enthalpy tests. These differences are thought to result from high-temperature real-gas effects.

  6. First principles studies of electron tunneling in proteins

    Science.gov (United States)

    Hayashi, Tomoyuki; Stuchebrukhov, Alexei A.

    2014-01-01

    A first principles study of electronic tunneling along the chain of seven Fe/S clusters in respiratory complex I, a key enzyme in the respiratory electron transport chain, is described. The broken-symmetry states of the Fe/S metal clusters calculated at both DFT and semi-empirical ZINDO levels were utilized to examine both the extremely weak electronic couplings between Fe/S clusters and the tunneling pathways, which provide a detailed atomistic-level description of the charge transfer process in the protein. One-electron tunneling approximation was found to hold within a reasonable accuracy, with only a moderate induced polarization of the core electrons. The method is demonstrated to be able to calculate accurately the coupling matrix elements as small as 10−4 cm−1. A distinct signature of the wave properties of electrons is observed as quantum interferences of multiple tunneling pathways. PMID:25383312

  7. Plane shock wave studies of geologic media

    International Nuclear Information System (INIS)

    Anderson, G.D.; Larson, D.B.

    1977-01-01

    Plane shock wave experiments have been conducted on eight geologic materials in an effort to determine the importance of time-dependent mechanical behavior. Of the eight rocks studied, only Westerly granite and nugget sandstone appear to show time independence. In the slightly porous materials (1-5 percent), Blair dolomite and sodium chloride, and in the highly porous (15 to 40 percent) rock, Mt. Helen tuff and Indiana limestone, time-dependent behavior is associated with the time required to close the available porosity. In water-saturated rocks the time dependence arises because the water that is present shows no indication of transformation to the higher pressure ice phases, thus suggesting the possibility that a metastable form of water exists under dynamic conditions

  8. Dextrose-induced subsynovial connective tissue fibrosis in the rabbit carpal tunnel: A potential model to study carpal tunnel syndrome?

    NARCIS (Netherlands)

    Oh, S.; Ettema, A.M.; Zhao, C.; Zobitz, M.E.; Wold, L.E.; An, K.N.; Amadio, P.C.

    2008-01-01

    In this pilot study, hypertonic dextrose solution was used to induce fibrosis of the subsynovial connective tissue (SSCT) and create an animal model of potential use in the study of carpal tunnel syndrome (CTS). The SSCT of the carpal tunnel in 15 New Zealand white rabbits were injected with 0.05 ml

  9. Scanning tunneling spectroscopy study of DNA conductivity

    Czech Academy of Sciences Publication Activity Database

    Kratochvílová, Irena; Král, Karel; Bunček, M.; Nešpůrek, Stanislav; Todorciuc, Tatiana; Weiter, M.; Navrátil, J.; Schneider, Bohdan; Pavluch, J.

    2008-01-01

    Roč. 6, č. 3 (2008), s. 422-426 ISSN 1895-1082 R&D Projects: GA AV ČR KAN401770651; GA MŠk OC 137; GA AV ČR KAN400720701; GA AV ČR KAN200100801 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z40500505; CEZ:AV0Z40550506 Keywords : molecular electronics * DNA * scanning tunneling microscopy * conductivity * charge carrier transport Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.448, year: 2008

  10. Experimental study of micro-shock tube flow

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Ouk; Kim, Gyu Wan; Rasel, Md. Alim Iftakhar [Dept. of Mechanical Engineering, Andong National University, Andong (Korea, Republic of); Kim, Heuy Dong [Fire Research Center, Korea Institute of Civil Engineering and Building Technology, Hwasung (Korea, Republic of)

    2015-03-15

    The flow characteristics in micro shock tube are investigated experimentally. Studies were carried out using a stainless steel micro shock tube. Shock and expansion wave was measured using 8 pressure sensors. The initial pressure ratio was varied from 4.3 to 30.5, and the diameter of tube was also changed from 3 mm to 6 mm. Diaphragm conditions were varied using two types of diaphragms. The results obtained show that the shock strength in the tube becomes stronger for an increase in the initial pressure ratio and diameter of tube. For the thinner diaphragm, the highest shock strength was found among varied diaphragm condition. Shock attenuation was highly influenced by the diameter of tube.

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

    Directory of Open Access Journals (Sweden)

    Hassan Bakhshandeh Amnieh

    2016-06-01

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

  12. Boundary Layer Transition and Trip Effectiveness on an Apollo Capsule in the JAXA High Enthalpy Shock Tunnel (HIEST) Facility

    Science.gov (United States)

    Kirk, Lindsay C.; Lillard, Randolph P.; Olejniczak, Joseph; Tanno, Hideyuki

    2015-01-01

    Computational assessments were performed to size boundary layer trips for a scaled Apollo capsule model in the High Enthalpy Shock Tunnel (HIEST) facility at the JAXA Kakuda Space Center in Japan. For stagnation conditions between 2 MJ/kg and 20 MJ/kg and between 10 MPa and 60 MPa, the appropriate trips were determined to be between 0.2 mm and 1.3 mm high, which provided kappa/delta values on the heatshield from 0.15 to 2.25. The tripped configuration consisted of an insert with a series of diamond shaped trips along the heatshield downstream of the stagnation point. Surface heat flux measurements were obtained on a capsule with a 250 mm diameter, 6.4% scale model, and pressure measurements were taken at axial stations along the nozzle walls. At low enthalpy conditions, the computational predictions agree favorably to the test data along the heatshield centerline. However, agreement becomes less favorable as the enthalpy increases conditions. The measured surface heat flux on the heatshield from the HIEST facility was under-predicted by the computations in these cases. Both smooth and tripped configurations were tested for comparison, and a post-test computational analysis showed that kappa/delta values based on the as-measured stagnation conditions ranged between 0.5 and 1.2. Tripped configurations for both 0.6 mm and 0.8 mm trip heights were able to effectively trip the flow to fully turbulent for a range of freestream conditions.

  13. Report Tunneling Cost Reduction Study prepared for Fermilab

    International Nuclear Information System (INIS)

    Not Available

    1999-01-01

    Fermi National Accelerator Laboratories has a need to review the costs of constructing the very long tunnels which would be required for housing the equipment for the proposed Very Large Hadron Collider (VLHC) project. Current tunneling costs are high, and the identification of potential means of significantly reducing them, and thereby helping to keep overall project costs within an acceptable budget, has assumed great importance. Fermilab has contracted with The Robbins Company to provide an up-to-date appraisal of tunneling technology, and to review the potential for substantially improving currently the state-of-practice performance and construction costs in particular. The Robbins Company was chosen for this task because of its long and successful experience in hard rock mechanical tunnel boring. In the past 40 years, Robbins has manufactured over 250 tunneling machines, the vast majority for hard rock applications. In addition to also supplying back-up equipment, Robbins has recently established a division dedicated to the manufacture of continuous conveying equipment for the efficient support of tunneling operations. The study extends beyond the tunnel boring machine (TBM) itself, and into the critical area of the logistics of the support of the machine as it advances, including manpower. It is restricted to proven methods using conventional technology, and its potential for incremental but meaningful improvement, rather than examining exotic and undeveloped means of rock excavation that have been proposed from time to time by the technical community. This is the first phase of what is expected to be a number of studies in increasing depth of technical detail, and as such has been restricted to the issues connected with the initial 34 kilometer circumference booster tunnel, and not the proposed 500 kilometer circumference tunnel housing the VLHC itself. The booster tunnel is entirely sited within low to medium strength limestone and dolomite formations

  14. Study of shock coalescence in laser-irradiated targets

    International Nuclear Information System (INIS)

    Coe, S.E.; Willi, O.; Afshar-Rad, T.; Rose, S.J.

    1988-01-01

    We report on the first direct experimental observation of the coalescence of two shocks induced by a shaped laser pulse. Optical streak photography of the rear surface of aluminum multiple step targets was used to study the breakout of these shocks and observe their behavior. The experimental results are compared with simulations by a one-dimensional Lagrangian hydrodynamic code

  15. Strong quasi-particle tunneling study in the paired quantum Hall states

    OpenAIRE

    Nomura, Kentaro; Yoshioka, Daijiro

    2001-01-01

    The quasi-particle tunneling phenomena in the paired fractional quantum Hall states are studied. A single point-contact system is first considered. Because of relevancy of the quasi-particle tunneling term, the strong tunneling regime should be investigated. Using the instanton method it is shown that the strong quasi-particle tunneling regime is described as the weak electron tunneling regime effectively. Expanding to the network model the paired quantum Hall liquid to insulator transition i...

  16. Experimental study of drag reduction in flumes and spillway tunnels

    Directory of Open Access Journals (Sweden)

    Ying-kui Wang

    2010-06-01

    Full Text Available Experiments in an open flume model and spillway tunnel model were carried out using drag reduction techniques. Two drag reduction techniques were adopted in the experiments: polymer addition and coating. The drag reduction effect of a polyacrylamide (PAM solution and dimethyl silicone oil coating were studied in the flume model experiments, and the results were analyzed. Experiments were then carried out with a model of the Xiluodu Hydropower Station, the second largest dam in China. In order to reduce the resistance, the spillway tunnels were internally coated with dimethyl silicone oil. This is the first time that these drag reduction techniques have been applied to so large a hydraulic model. The experimental results show that the coating technique can effectively increase flood discharge. The outlet velocity and the jet trajectory distance are also increased, which enhances the energy dissipation of the spillway tunnel.

  17. Learning from case studies and monitoring of Dutch tunnel projects

    NARCIS (Netherlands)

    Korff, M.

    2017-01-01

    Individuals and project-based organisations in the construction industry can learn in a (more) systematic way from case studies and the monitoring of underground construction works. Underground construction projects such as tunnels and excavations suffer as much or more from failure costs

  18. Evaluation of the Influence Caused by Tunnel Construction on Groundwater Environment: A Case Study of Tongluoshan Tunnel, China

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2015-01-01

    Full Text Available Problems related to water inflow during tunnel construction are challenging to designers, workers, and management departments, as they can threaten tunneling project from safety, time, and economic aspects. Identifying the impacts on groundwater environment resulting from tunnel drainage and making a correct assessment before tunnel construction is essential to better understand troubles that would be encountered during tunnel excavation and helpful to adopt appropriate countermeasures to minimize the influences. This study presents an indicator system and quantifies each indicator of Tongluoshan tunnel, which is located in southwest China with a length of 5.2 km and mainly passes through carbonate rocks and sandstones, based on field investigation and related technological reports. Then, an evaluation is made using fuzzy comprehensive assessment method, with a result showing that it had influenced the local groundwater environment at a moderate degree. Information fed back from environmental investigation and hydrologic monitoring carried out during the main construction period proves the evaluation, as the flow of some springs and streams located beside the tunnel route was found experiencing an apparent decline.

  19. Shock induced melting of lead (experimental study)

    International Nuclear Information System (INIS)

    Mabire, Catherine; Hereil, Pierre L.

    2002-01-01

    To investigate melting on release of lead, two shock compression measurements have been carried out at 51 GPa. In the first one, a pyrometric measurement has been performed at the Pb/LiF interface. In the second one, the Pb/LiF interface velocity has been recorded using VISAR measurement technique. VISAR and radiance profile are in good agreement and seem to show melting on release of lead

  20. High-power laser experiments to study collisionless shock generation

    Directory of Open Access Journals (Sweden)

    Sakawa Y.

    2013-11-01

    Full Text Available A collisionless Weibel-instability mediated shock in a self-generated magnetic field is studied using two-dimensional particle-in-cell simulation [Kato and Takabe, Astophys. J. Lett. 681, L93 (2008]. It is predicted that the generation of the Weibel shock requires to use NIF-class high-power laser system. Collisionless electrostatic shocks are produced in counter-streaming plasmas using Gekko XII laser system [Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011]. A NIF facility time proposal is approved to study the formation of the collisionless Weibel shock. OMEGA and OMEGA EP experiments have been started to study the plasma conditions of counter-streaming plasmas required for the NIF experiment using Thomson scattering and to develop proton radiography diagnostics.

  1. Monte Carlo study of neutrino acceleration in supernova shocks

    International Nuclear Information System (INIS)

    Kazanas, Demosthenes; Ellison, D.C.; National Aeronautics and Space Administration, Greenbelt, MD

    1981-01-01

    The first order Fermi acceleration mechanism of cosmic rays in shocks may be at work for neutrinos in supernova shocks when the latter are at densities rho>10 13 g cm -3 at which the core material is opaque to neutrinos. A Monte Carlo approach to study this effect is employed and the emerging neutrino power law spectra are presented. The increased energy acquired by the neutrinos may facilitate their detection in supernova explosions and provide information about the physics of collapse

  2. X-ray study of bow shocks in runaway stars

    Science.gov (United States)

    De Becker, M.; del Valle, M. V.; Romero, G. E.; Peri, C. S.; Benaglia, P.

    2017-11-01

    Massive runaway stars produce bow shocks through the interaction of their winds with the interstellar medium, with the prospect for particle acceleration by the shocks. These objects are consequently candidates for non-thermal emission. Our aim is to investigate the X-ray emission from these sources. We observed with XMM-Newton a sample of five bow shock runaways, which constitutes a significant improvement of the sample of bow shock runaways studied in X-rays so far. A careful analysis of the data did not reveal any X-ray emission related to the bow shocks. However, X-ray emission from the stars is detected, in agreement with the expected thermal emission from stellar winds. On the basis of background measurements we derive conservative upper limits between 0.3 and 10 keV on the bow shocks emission. Using a simple radiation model, these limits together with radio upper limits allow us to constrain some of the main physical quantities involved in the non-thermal emission processes, such as the magnetic field strength and the amount of incident infrared photons. The reasons likely responsible for the non-detection of non-thermal radiation are discussed. Finally, using energy budget arguments, we investigate the detectability of inverse Compton X-rays in a more extended sample of catalogued runaway star bow shocks. From our analysis we conclude that a clear identification of non-thermal X-rays from massive runaway bow shocks requires one order of magnitude (or higher) sensitivity improvement with respect to present observatories.

  3. First results of transcritical magnetized collisionless shock studies on MSX

    Science.gov (United States)

    Weber, T. E.; Smith, R. J.; Hutchinson, T. M.; Taylor, S. F.; Hsu, S. C.

    2014-10-01

    Magnetized collisionless shocks exhibit transitional length and time scales much shorter than can be created through collisional processes. They are common throughout the cosmos, but have historically proven difficult to create in the laboratory. The Magnetized Shock Experiment (MSX) at LANL produces super-Alfvénic shocks through the acceleration and subsequent stagnation of Field Reversed Configuration (FRC) plasmoids against a strong magnetic mirror and flux-conserving vacuum boundary. Plasma flows have been produced with sonic and Alfvén Mach numbers up to ~10 over a wide range of plasma beta with embedded perpendicular, oblique, and parallel magnetic field. Macroscopic ion skin-depth and long ion-gyroperiod enable diagnostic access to relevant shock physics using common methods. Variable plasmoid velocity, density, temperature, and magnetic field provide access to a wide range of shock conditions, and a campaign to study the physics of transcritical and supercritical shocks within the FRC plasmoid is currently underway. An overview of the experimental design, diagnostics suite, physics objectives, and recent results will be presented. Supported by DOE Office of Fusion Energy Sciences under DOE Contract DE-AC52-06NA25369.

  4. Scanning tunneling microscopy and spectroscopy studies of graphite edges

    International Nuclear Information System (INIS)

    Niimi, Y.; Matsui, T.; Kambara, H.; Tagami, K.; Tsukada, M.; Fukuyama, Hiroshi

    2005-01-01

    We studied experimentally and theoretically the electronic local density of states (LDOS) near single-step edges at the surface of exfoliated graphite. In scanning tunneling microscopy measurements, we observed the (3x3)R30 o and honeycomb superstructures extending over 3-4-bar nm both from the zigzag and armchair edges. Calculations based on a density-functional-derived non-orthogonal tight-binding model show that these superstructures can coexist if the two types of edges admix each other in real graphite step edges. Scanning tunneling spectroscopy measurements near the zigzag edge reveal a clear peak in the LDOS at an energy below the Fermi energy by 20-bar meV. No such a peak was observed near the armchair edge. We concluded that this peak corresponds to the 'edge state' theoretically predicted for graphene ribbons, since a similar prominent LDOS peak due to the edge state is obtained by the first principles calculations

  5. A comparative study on shock compression of nanocrystalline Al and Cu: Shock profiles and microscopic views of plasticity

    International Nuclear Information System (INIS)

    Ma, Wen; Hou, Yong; Zhu, Wenjun

    2013-01-01

    Shock compressions of nanocrystalline (nc) metals Al and Cu with the same grain size and texture are studied by using molecular dynamics simulations. Results have revealed that the shock front of both Al and Cu can be divided into three stages: elastic, grain-boundary-mediated, and dislocation-mediated plastic deformation. The transition planes among these three stages are proven to be non-planar by two-dimensional shock response analysis, including local stress, shear, temperature, and atom configuration. The difference between shocked Al and Cu is that the rise rate of the elastic stage of Cu is slightly higher than that of Al, and that the shock-front width of Al is wider than Cu at the same loading conditions. For the plastic stage, the dislocation density of shocked Al is lower than Cu, and the contribution of grain-boundary-mediated plasticity to shock front and strain for nc Al is more pronounced than for nc Cu. These results are explained through intrinsic material properties and atomistic analysis of the plastic process. In the case of the shocked Al sample, partial dislocations, perfect dislocations, and twins are observed, but few evidence of perfect dislocations and twins are observed in the shocked Cu

  6. Numerical Study of Shock Wave Attenuation in Two-Dimensional Ducts Using Solid Obstacles: How to Utilize Shock Focusing Techniques to Attenuate Shock Waves

    Directory of Open Access Journals (Sweden)

    Qian Wan

    2015-04-01

    Full Text Available Research on shock wave mitigation in channels has been a topic of much attention in the shock wave community. One approach to attenuate an incident shock wave is to use obstacles of various geometries arranged in different patterns. This work is inspired by the study from Chaudhuri et al. (2013, in which cylinders, squares and triangles placed in staggered and non-staggered subsequent columns were used to attenuate a planar incident shock wave. Here, we present numerical simulations using a different obstacle pattern. Instead of using a matrix of obstacles, an arrangement of square or cylindrical obstacles placed along a logarithmic spiral curve is investigated, which is motivated by our previous work on shock focusing using logarithmic spirals. Results show that obstacles placed along a logarithmic spiral can delay both the transmitted and the reflected shock wave. For different incident shock Mach numbers, away from the logarithmic spiral design Mach number, this shape is effective to either delay the transmitted or the reflected shock wave. Results also confirm that the degree of attenuation depends on the obstacle shape, effective flow area and obstacle arrangement, much like other obstacle configurations.

  7. Experimental Study of Shock Generated Compressible Vortex Ring

    Science.gov (United States)

    Das, Debopam; Arakeri, Jaywant H.; Krothapalli, Anjaneyulu

    2000-11-01

    Formation of a compressible vortex ring and generation of sound associated with it is studied experimentally. Impulse of a shock wave is used to generate a vortex ring from the open end of a shock-tube. Vortex ring formation process has been studied in details using particle image Velocimetry (PIV). As the shock wave exits the tube it diffracts and expands. A circular vortex sheet forms at the edge and rolls up into a vortex ring. Far field microphone measurement shows that the acoustic pressure consists of a spike due to shock wave followed by a low frequency pressure wave of decaying nature, superimposed with high frequency pressure wave. Acoustic waves consist of waves due to expansion, waves formed in the tube during diaphragm breakage and waves associated with the vortex ring and shear-layer vortices. Unsteady evolution of the vortex ring and shear-layer vortices in the jet behind the ring is studied by measuring the velocity field using PIV. Corresponding vorticity field, circulation around the vortex core and growth rate of the vortex core is calculated from the measured velocity field. The velocity field in a compressible vortex ring differs from that of an incompressible ring due to the contribution from both shock and vortex ring.

  8. Study of tunneling time with Larmor clock and neutron absorption

    International Nuclear Information System (INIS)

    Hino, M.; Tasaki, S.; Ebisawa, T.; Kawai, T.; Utsuro, M.; Achiwa, N.

    2001-01-01

    Tunnel effect is one of the most typical quantum mechanical phenomena which cannot be understood in the classical physics. Though the tunnel phenomenon itself is precisely defined on the basis of quantum mechanics, tunneling time, the time for a particle to pass a tunnel barrier, has been a controversial issue because time is a parameter to show the rate of change of physical phenomena in quantum mechanics but has no corresponding quantum operator. In the present study, Larmor precession of the neutrons passing a Permalloy45 (PA) thin film was measured as a function of neutron incident angle to the film by using neutron spin-echo instrument at KUR and neutron interferometer at JRR-3. Results are compared with a calculation based on one-dimensional Schroedinger equation. The agreement between the experiment and the plane-wave simulation is very good which means that the neutrons are not described in particle picture here, and the Larmor time defined as number of spin precession divided by angular velocity no more represents the time for a particle to pass the barrier although it is a kind of the phase time. In order to emphasize the particle picture, effects of neutron absorption were considered theoretically. Larmor precession passing through a Fabry-Perot magnetic thin film which has two potential barriers (quantum well) for up-spin neutrons were measured for two cases that the film is hot neutron absorptive (PA-Ge-PA) and strongly absorptive (Se-Ge/Gd-Se). Here Ge, Gd and Se represent germanium, gadolinium and Supersendust, respectively. While down-spin neutrons feel only a small potential barrier. Spin-dependent reflectivity and transmission of the Fabry-Perot magnetic films were also measured as functions of the neutron incident angle to the film. Experimental results of the non-absorptive film show that the neutron spin precession cannot be treated as the classical motion of a magnetic moment feeling torque under applied magnetic field like the Larmor

  9. Parametric study on the performance of automotive MR shock absorbers

    Science.gov (United States)

    Gołdasz, J.; Dzierżek, S.

    2016-09-01

    The paper contains the results of a parametric study to explore the influence of various quantities on the performance range of semi-active automotive shock absorbers using the magnetorheological (MR) fluid under steady-state and transient excitations. The analysis was performed with simulated data and using a standard single-tube shock absorber configuration with a single-gap MR valve. Additionally, the impact of material variables and valves geometry was examined as the parameters were varied and its dynamic range studied.

  10. Model uncertainty of various settlement estimation methods in shallow tunnels excavation; case study: Qom subway tunnel

    Science.gov (United States)

    Khademian, Amir; Abdollahipour, Hamed; Bagherpour, Raheb; Faramarzi, Lohrasb

    2017-10-01

    In addition to the numerous planning and executive challenges, underground excavation in urban areas is always followed by certain destructive effects especially on the ground surface; ground settlement is the most important of these effects for which estimation there exist different empirical, analytical and numerical methods. Since geotechnical models are associated with considerable model uncertainty, this study characterized the model uncertainty of settlement estimation models through a systematic comparison between model predictions and past performance data derived from instrumentation. To do so, the amount of surface settlement induced by excavation of the Qom subway tunnel was estimated via empirical (Peck), analytical (Loganathan and Poulos) and numerical (FDM) methods; the resulting maximum settlement value of each model were 1.86, 2.02 and 1.52 cm, respectively. The comparison of these predicted amounts with the actual data from instrumentation was employed to specify the uncertainty of each model. The numerical model outcomes, with a relative error of 3.8%, best matched the reality and the analytical method, with a relative error of 27.8%, yielded the highest level of model uncertainty.

  11. Clinical Study on Five Cases of Carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    Kim Il Hwan

    2001-12-01

    Full Text Available Objections : The purpose of the study was to evaluate the effectiveness of treating the carpal tunnel syndrome by using both the Herbal Acupuncture and herbal medicine therapy on five cases. Methods : For the Herbal Acupuncture, Jungseonguhhyl No. 1 and Hwanglyunhaedoktang were used. For the herbal medicine, Dangguihwalhyul-tang was used. The patients were treated once in every two days; the result was evaluated after ten treatments. Patients' conditions were monitored through their testimony, phalen's test, nerve conduction study and electromyography. Results : In all five cases, the patients showed improvement; in four cases, the patients no longer had most of the clinical symptoms. Based on the result of the nerve conduction study, for the four cases in which the patients no longer displayed most of the clinical symptoms, their nerve conduction rate improved; for the remaining one case, the patient's nerve conduction rate deteriorated. Conclusions : The results of this study demonstrate that combining the Herbal Acupuncture and herbal medicine therapy can have noticeable effects in treating the carpal tunnel syndrome; developing more variety of the herbal acupuncture would lead to even better treatment results.

  12. Diesel bus emissions measured in a tunnel study.

    Science.gov (United States)

    Jamriska, Milan; Morawska, Lidia; Thomas, Steven; He, Congrong

    2004-12-15

    The emission factors of a bus fleet consisting of approximately 300 diesel-powered buses were measured in a tunnel study under well-controlled conditions during a 2-d monitoring campaign in Brisbane. Particle number and mass concentration levels of submicrometer particles and PM2.5 were monitored by SMPS and DustTrak instruments at the tunnel's entrance and exit, respectively. Correlation between DustTrak and TEOM response to diesel emissions was assessed, and the DustTrak results were recalculated into TEOM equivalent data. The mean value of the number and mass emission factors was (3.11+/-2.41) x 10(14) particles km(-1) for submicrometer particles and 583+/-451 mg km(-1) for PM2.5 (DustTrak), respectively. TEOM PM2.5 equivalent emission factor was 267+/-207 mg km(-1). The results are in good agreement with the emission factors determined from steady-state dynamometer testing of 12 buses from the same Brisbane City bus fleet. The results indicate that when carefully designed, both approaches, the dynamometer and on-road studies, can provide comparable results, applicable for the assessment of the effect of traffic emissions on airborne particle pollution. A brief overview of emission factors determined from other on-road and dynamometer studies reported in the literature as well as with the regulatory values used for the vehicle emission inventory assessment is presented and compared with the results obtained in this study.

  13. Studying the Effect of Tunnel Depth Variation on the Specific Energy of TBM, Case Study: Karaj–Tehran (Iran Water Conveyance Tunnel

    Directory of Open Access Journals (Sweden)

    Majid Mirahmadi

    2016-09-01

    Full Text Available The tunnel-boring machine (TBM is a common piece of equipment used in tunneling projects. For planning a mechanical excavation project, prediction of TBM performance and the specification of design elements such as required forces are critical. The specific energy of excavation (SE, i.e. drilling energy consumption per unit volume of rock mass, is a crucial parameter for performance prediction of a TBM. In this study, the effect of variation of tunnel depth on SE by considering the post-failure behavior of rock mass was investigated. Several new relations between SE and tunnel depth are proposed according to the statistical analysis obtained from Karaj – Tehran Water Conveyance Tunnel real data. The results showed that there is a direct relation between both parameters and. Polynomial equations are proposed as the best expression of the correlation between these parameters.

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

    International Nuclear Information System (INIS)

    Andersson, Christer; Soederhaell, Joergen

    2001-12-01

    Maintenance records including scaling, shotcreting and bolting have been kept since the excavation start of Aespoe HRL 1990 together with records of groundwater flow and all other activities taking place in the tunnels. When the facility was constructed one objective was to limit the rock support as much as possible. The reason for this was that it should be possible to go back and easily study the exposed rock surface. Support during the operational phase has only been carried out where and when necessary. This type of maintenance and its location is documented in the digital database each time. The maintenance records have been compiled and areas requiring more maintenance than average noted. An interview has also been held with one of the miners conducting scaling and bolting in the tunnel. His experiences together with the study of the database maintenance records led to the selection of certain areas in the tunnel to be studied by numerical modelling. The probable reason for the need of additional maintenance in all areas, not only these numerically modelled, has been investigated. Almost all maintenance in the main tunnel both during construction and the operational phase has been located in the widened curves of the access tunnel. The maintenance is also located in areas containing veins or intrusions of Smaaland granite or fine-grained granite. These areas are often located in fracture zones of different sizes or show an increasing fracture frequency. The areas numerically modelled indicate stress concentrations or unloaded stress conditions. The stress concentrations are created by the geometry of the niches and side-tunnels in relation to the in situ stress field. The angle between the tunnel and the major principal stress has an impact on the need for maintenance. The areas with the largest angles towards the principal stress direction need more maintenance than the areas almost parallel to the major principal stress direction. The maintenance work in

  15. Electron Dropout Echoes Induced by Interplanetary Shock: A Statistical Study

    Science.gov (United States)

    Liu, Z.; Zong, Q.; Hao, Y.; Zhou, X.; Ma, X.; Liu, Y.

    2017-12-01

    "Electron dropout echo" as indicated by repeated moderate dropout and recovery signatures of the flux of energetic electron in the out radiation belt region has been investigated systematically. The electron dropout and its echoes are usually found for higher energy (> 300 keV) channels fluxes, whereas the flux enhancements are obvious for lower energy electrons simultaneously after the interplanetary shock arrives at the Earth's geosynchronous orbit. 104 dropout echo events have been found from 215 interplanetary shock events from 1998 to 2007 based on LANL satellite data. In analogy to substorm injections, these 104 events could be naturally divided into two categories: dispersionless (49 events) or dispersive (55 events) according to the energy dispersion of the initial dropout. It is found that locations of dispersionless events are distributed mainly in the duskside magnetosphere. Further, the obtained locations derived from dispersive events with the time-of-flight technique of the initial dropout regions are mainly located at the duskside as well. Statistical studies have shown that the effect of shock normal, interplanetary magnetic field Bz and solar wind dynamic pressure may be insignificant to these electron dropout events. We suggest that the electric field impulse induced by the IP shock produces a more pronounced inward migration of electrons at the dusk side, resulting in the observed dusk-side moderate dropout of electron flux and its consequent echoes.

  16. Automatic control study of the icing research tunnel refrigeration system

    Science.gov (United States)

    Kieffer, Arthur W.; Soeder, Ronald H.

    1991-01-01

    The Icing Research Tunnel (IRT) at the NASA Lewis Research Center is a subsonic, closed-return atmospheric tunnel. The tunnel includes a heat exchanger and a refrigeration plant to achieve the desired air temperature and a spray system to generate the type of icing conditions that would be encountered by aircraft. At the present time, the tunnel air temperature is controlled by manual adjustment of freon refrigerant flow control valves. An upgrade of this facility calls for these control valves to be adjusted by an automatic controller. The digital computer simulation of the IRT refrigeration plant and the automatic controller that was used in the simulation are discussed.

  17. Combined free-stream disturbance measurements and receptivity studies in hypersonic wind tunnels by means of a slender wedge probe and direct numerical simulation

    Science.gov (United States)

    Wagner, Alexander; Schülein, Erich; Petervari, René; Hannemann, Klaus; Ali, Syed R. C.; Cerminara, Adriano; Sandham, Neil D.

    2018-05-01

    Combined free-stream disturbance measurements and receptivity studies in hypersonic wind tunnels were conducted by means of a slender wedge probe and direct numerical simulation. The study comprises comparative tunnel noise measurements at Mach 3, 6 and 7.4 in two Ludwieg tube facilities and a shock tunnel. Surface pressure fluctuations were measured over a wide range of frequencies and test conditions including harsh test environments not accessible to measurement techniques such as pitot probes and hot-wire anemometry. Quantitative results of the tunnel noise are provided in frequency ranges relevant for hypersonic boundary layer transition. In combination with the experimental studies, direct numerical simulations of the leading-edge receptivity to fast and slow acoustic waves were performed for the slender wedge probe at conditions corresponding to the experimental free-stream conditions. The receptivity to fast acoustic waves was found to be characterized by an early amplification of the induced fast mode. For slow acoustic waves an initial decay was found close to the leading edge. At all Mach numbers, and for all considered frequencies, the leading-edge receptivity to fast acoustic waves was found to be higher than the receptivity to slow acoustic waves. Further, the effect of inclination angles of the acoustic wave with respect to the flow direction was investigated. The combined numerical and experimental approach in the present study confirmed the previous suggestion that the slow acoustic wave is the dominant acoustic mode in noisy hypersonic wind tunnels.

  18. Study on water migration of tunnel surrounding rock in nuclear waste repository based on coupling theory

    International Nuclear Information System (INIS)

    Jiang Zhongming; Zhang Xinmin

    2008-01-01

    Excavation of tunnel changes not only the stresses and deformation of tunnel surrounding rock, but also disturbs the underground water environment in tunnel surrounding rock Water migration happens due to variation of pore water pressure and redistribution. Based on the mechanics of porous media, saturated and unsaturated hydro-mechanical coupling analysis method is employed to study the variation of the stresses, deformation and pore pressure of the surrounding rock. Case study indicates that the excavation of tunnel will induce redistribution of stress and pore water pressure. Redistribution of pore water pressure will seriously affect on evaluation of surrounding rock stability and diffusion of nucleon in the pore water. (authors)

  19. Case study on ventilation method development for Bar-Boljare highway tunnels construction in Montenegro

    Directory of Open Access Journals (Sweden)

    Cvjetić Aleksandar S.

    2017-01-01

    Full Text Available Sometimes tunnel construction is a necessity regardless of its purpose due to many reasons, to mention some of them: limited space, safe operation, environmental protection etc. In those cases, one of the main aspects concerning an appropriate design of a tunnel construction is site ventilation. Ventilation is required during the construction of any tunnel regardless of technology used to construct it. Three major construction ventilation schemes are typically applied. Which one will be use are often in dependency of the site requirements. In this paper is presented case study on ventilation method development for the highway tunnels construction and it includes ventilation solutions for tunnels ‘Suka’, ‘Vežešnik’, ‘Mrke’ and ‘Vjeternik’ during construction phase. The tunnels are part of the Bar-Boljare highway which is also a part of the Trans-European Highway (THE through the Republic of Montenegro.

  20. Electron holography study on the microstructure of magnetic tunnelling junctions

    International Nuclear Information System (INIS)

    Xu, Q.Y.; Wang, Y.G.; You, B.; Du, J.; Hu, A.; Zhang, Z.

    2004-01-01

    Electron holography was applied to study the microstructure evolution of magnetic tunnelling junctions (MTJs) CoFe/AlO x /Co annealed at different temperatures. A mean inner potential barrier was observed in the as-deposited MTJ sample, while it was changed to a potential well after a 200 deg. C or a 400 deg. C annealing. It is suggested that the oxygen atoms were redistributed during the annealing, which left metallic atoms acting as acceptors to confine the electrons, leading to the decrease of the potential of the AlO x barrier layer. The results suggest that the electron holography may be a useful tool for the study of the microstructure of amorphous materials

  1. Study of the geometrical resonances of superconducting tunnel junctions

    DEFF Research Database (Denmark)

    Sørensen, O. Hoffmann; Finnegan, T.F.; Pedersen, Niels Falsig

    1973-01-01

    The resonant cavity structure of superconducting Sn-Sn-oxide-Sn tunnel junctions has been investigated via photon-assisted quasiparticle tunneling. We find that the temperature-dependent losses at 35 GHz are determined by the surface resistance of the Sn films for reduced temperatures between 0...

  2. Theoretical study of short pile effect in tunnel excavation

    Science.gov (United States)

    Tian, Xiao-yan; Liu, Jing; Gao, Xiao-mei; Li, Yuan

    2017-09-01

    The Misaki Sato Go ideal elastoplastic model is adopted and the two stage analysis theory is used to study the effect of tunnel excavation on short pile effect in this paper. In the first stage, the free field vertical displacement of the soil at the corresponding pile location is obtained by using empirical formula. In the second stage, the displacement is applied to the corresponding pile location. The equilibrium condition of micro physical differential equation settlement of piles. Then through logical deduction and the boundary condition expressions of the settlement calculation, obtain the pile side friction resistance and axial force of the week. Finally, an engineering example is used to analyze the influence of the change of main parameters on their effects.

  3. Study of the Integration of the CNU-TS-1 Mobile Tunnel Monitoring System.

    Science.gov (United States)

    Du, Liming; Zhong, Ruofei; Sun, Haili; Zhu, Qiang; Zhang, Zhen

    2018-02-01

    A rapid, precise and automated means for the regular inspection and maintenance of a large number of tunnels is needed. Based on the depth study of the tunnel monitoring method, the CNU-TS-1 mobile tunnel monitoring system (TS1) is developed and presented. It can efficiently obtain the cross-sections that are orthogonal to the tunnel in a dynamic way, and the control measurements that depend on design data are eliminated. By using odometers to locate the cross-sections and correcting the data based on longitudinal joints of tunnel segment lining, the cost of the system has been significantly reduced, and the interval between adjacent cross-sections can reach 1-2 cm when pushed to collect data at a normal walking speed. Meanwhile, the relative deformation of tunnel can be analyzed by selecting cross-sections from original data. Through the measurement of the actual tunnel, the applicability of the system for tunnel deformation detection is verified, and the system is shown to be 15 times more efficient than that of the total station. The simulation experiment of the tunnel deformation indicates that the measurement accuracy of TS1 for cross-sections is 1.1 mm. Compared with the traditional method, TS1 improves the efficiency as well as increases the density of the obtained points.

  4. Study of the Integration of the CNU-TS-1 Mobile Tunnel Monitoring System

    Directory of Open Access Journals (Sweden)

    Liming Du

    2018-02-01

    Full Text Available A rapid, precise and automated means for the regular inspection and maintenance of a large number of tunnels is needed. Based on the depth study of the tunnel monitoring method, the CNU-TS-1 mobile tunnel monitoring system (TS1 is developed and presented. It can efficiently obtain the cross-sections that are orthogonal to the tunnel in a dynamic way, and the control measurements that depend on design data are eliminated. By using odometers to locate the cross-sections and correcting the data based on longitudinal joints of tunnel segment lining, the cost of the system has been significantly reduced, and the interval between adjacent cross-sections can reach 1–2 cm when pushed to collect data at a normal walking speed. Meanwhile, the relative deformation of tunnel can be analyzed by selecting cross-sections from original data. Through the measurement of the actual tunnel, the applicability of the system for tunnel deformation detection is verified, and the system is shown to be 15 times more efficient than that of the total station. The simulation experiment of the tunnel deformation indicates that the measurement accuracy of TS1 for cross-sections is 1.1 mm. Compared with the traditional method, TS1 improves the efficiency as well as increases the density of the obtained points.

  5. Development of the safety control framework for shield tunneling in close proximity to the operational subway tunnels: case studies in mainland China.

    Science.gov (United States)

    Li, Xinggao; Yuan, Dajun

    2016-01-01

    China's largest cities like Beijing and Shanghai have seen a sharp increase in subway network development as a result of the rapid urbanization in the last decade. The cities are still expanding their subway networks now, and many shield tunnels are being or will be constructed in close proximity to the existing operational subway tunnels. The execution plans for the new nearby shield tunnel construction calls for the development of a safety control framework-a set of control standards and best practices to help organizations manage the risks involved. Typical case studies and relevant key technical parameters are presented with a view to presenting the resulting safety control framework. The framework, created through collaboration among the relevant parties, addresses and manages the risks in a systematic way based on actual conditions of each tunnel crossing construction. The framework consists of six parts: (1) inspecting the operational subway tunnels; (2) deciding allowed movements of the existing tunnels and tracks; (3) simulating effects of the shield tunneling on the existing tunnels; (4) doing preparation work; (5) monitoring design and information management; and (6) measures and activation mechanism of the countermeasures. The six components are explained and demonstrated in detail. In the end, discussions made involve construction and post-construction settlement of the operational tunnel, application of the remedial grouting to rectify excessive settlements of the operational tunnel, and use of the innovative tool of the optical fiber measurement for tunnel movement monitoring. It is concluded that the construction movement of the tunnel can be controlled within 15 mm when the shield machine is <7 m in excavation diameter. The post-construction settlement of the tunnel buried in the very soft ground is much greater than its construction settlement, and last several years until reaching a final stable state. Two cases are outlined to demonstrate the

  6. Stereo Photogrammetry Measurements of the Position and Attitude of a Nozzle-Plume/Shock-Wave Interaction Model in the NASA Ames 9- by 7-Ft Supersonic Wind Tunnel

    Science.gov (United States)

    Schairer, Edward T.; Kushner, Laura K.; Drain, Bethany A.; Heineck, James T.; Durston, Donald A.

    2017-01-01

    Stereo photogrammetry was used to measure the position and attitude of a slender body of revolution during nozzle-plume/shock-wave interaction tests in the NASA Ames 9- by 7-Ft Supersonic Wind Tunnel. The model support system was designed to allow the model to be placed at many locations in the test section relative to a pressure rail on one sidewall. It included a streamwise traverse as well as a thin blade that offset the model axis from the sting axis. With these features the support system was more flexible than usual resulting in higher-than-usual uncertainty in the position and attitude of the model. Also contributing to this uncertainty were the absence of a balance, so corrections for sting deflections could not be applied, and the wings-vertical orientation of the model, which precluded using a gravity-based accelerometer to measure pitch angle. Therefore, stereo photogrammetry was chosen to provide independent measures of the model position and orientation. This paper describes the photogrammetry system and presents selected results from the test.

  7. Emission factors from road traffic from a tunnel study (Gubrist tunnel, Switzerland). Part 1 Concept and first results

    Energy Technology Data Exchange (ETDEWEB)

    Staehelin, Johannes; Brunner, Dominik; Baumle, Martin [Atmospheric Science, ETH-Hoenggerberg, Zuerich (Switzerland); Schlapfer, Kurt [Carbotech AG, Basel (Switzerland); Burgin, Toni; Meier, Markus [Amt fuer Technische Anlagen und Lufthygiene Kanton Zuerich ATAL, Zuerich (Switzerland); Steinemann, Urs [Ingenieurbuero Steinemann, Wollerau (Switzerland); Schneider, Stefan; Zahner, Christoph; Keiser, Stephan [Planungsbuero Jud AG, Zuerich (Switzerland); Stahel, Werner; Keller, Christian [Sem. for Statistics, ETH-Z, Zuerich (Switzerland)

    1995-06-22

    In the industrialized world a large part of the emission of the primary air pollutants (NO{sub x}, volatile organic compounds (VOC) and CO) originates from road traffic. Here we present the concept and first results of a tunnel study which took place from September 20th to September 26th, 1993, at the Gubrist tunnel (close to Zuerich, Switzerland) in which the emission factors of a large number of individual VOCs, total hydrocarbons (t-HC), CO, NO{sub x} and SO{sub 2} are determined. The first tentative results of the emission factors of NO{sub x}, CO, t-HC and 26 individual hydrocarbons (alkanes and aromatics in the volatility range from n-heptane to n-decane) for the average of all vehicles and the light duty vehicles at an average speed of 90 km/h are given

  8. The shock tube as wave reactor for kinetic studies and material systems

    Energy Technology Data Exchange (ETDEWEB)

    Bhaskaran, K.A. [Indian Institute of Technology, Chennai (India). Department of Mechanical Engineering; Roth, P. [Gerhard Mercator Universitat, Duisberg (Germany). Institut fur Verbrennung und Gasdynamik

    2002-07-01

    Several important reviews of shock tube kinetics have appeared earlier, prominent among them being 'Shock Tube Technique in Chemical Kinetics' by Belford and Strehlow (Ann Rev Phys Chem 20 (1969) 247), 'Chemical Reaction of Shock Waves' by Wagner (Proceedings of the Eighth International Shock Tube Symposium (1971) 4/1), 'Shock Tube and Shock Wave Research' by Bauer and Lewis (Proceedings of the 11th International Symposium on Shock Tubes and Waves (1977) 269), 'Shock Waves in Chemistry' edited by Assa Lifshitz (Shock Waves in Chemistry, 1981) and 'Shock Tube Techniques in Chemical Kinetics' by Wing Tsang and Assa Lifshitz (Annu Rev Phys Chem 41 (1990) 559). A critical analysis of the different shock tube techniques, their limitations and suggestions to improve the accuracy of the data produced are contained in these reviews. The purpose of this article is to present the current status of kinetic research with emphasis on the diagnostic techniques. Selected studies on homogeneous and dispersed systems are presented to bring out the versatility of the shock tube technique. The use of the shock tube as high temperature wave reactor for gas phase material synthesis is also highlighted. (author)

  9. Dynamic Tunnel Usability Study: Format Recommendations for Synthetic Vision System Primary Flight Displays

    Science.gov (United States)

    Arthur, Jarvis J., III; Prinzel, Lawrence J., III; Kramer, Lynda J.; Bailey, Randall E.

    2006-01-01

    A usability study evaluating dynamic tunnel concepts has been completed under the Aviation Safety and Security Program, Synthetic Vision Systems Project. The usability study was conducted in the Visual Imaging Simulator for Transport Aircraft Systems (VISTAS) III simulator in the form of questionnaires and pilot-in-the-loop simulation sessions. Twelve commercial pilots participated in the study to determine their preferences via paired comparisons and subjective rankings regarding the color, line thickness and sensitivity of the dynamic tunnel. The results of the study showed that color was not significant in pilot preference paired comparisons or in pilot rankings. Line thickness was significant for both pilot preference paired comparisons and in pilot rankings. The preferred line/halo thickness combination was a line width of 3 pixels and a halo of 4 pixels. Finally, pilots were asked their preference for the current dynamic tunnel compared to a less sensitive dynamic tunnel. The current dynamic tunnel constantly gives feedback to the pilot with regard to path error while the less sensitive tunnel only changes as the path error approaches the edges of the tunnel. The tunnel sensitivity comparison results were not statistically significant.

  10. A numerical study of fundamental shock noise mechanisms. Ph.D. Thesis - Cornell Univ.

    Science.gov (United States)

    Meadows, Kristine R.

    1995-01-01

    The results of this thesis demonstrate that direct numerical simulation can predict sound generation in unsteady aerodynamic flows containing shock waves. Shock waves can be significant sources of sound in high speed jet flows, on helicopter blades, and in supersonic combustion inlets. Direct computation of sound permits the prediction of noise levels in the preliminary design stage and can be used as a tool to focus experimental studies, thereby reducing cost and increasing the probability of a successfully quiet product in less time. This thesis reveals and investigates two mechanisms fundamental to sound generation by shocked flows: shock motion and shock deformation. Shock motion is modeled by the interaction of a sound wave with a shock. During the interaction, the shock wave begins to move and the sound pressure is amplified as the wave passes through the shock. The numerical approach presented in this thesis is validated by the comparison of results obtained in a quasi-one dimensional simulation with linear theory. Analysis of the perturbation energy demonstrated for the first time that acoustic energy is generated by the interaction. Shock deformation is investigated by the numerical simulation of a ring vortex interacting with a shock. This interaction models the passage of turbulent structures through the shock wave. The simulation demonstrates that both acoustic waves and contact surfaces are generated downstream during the interaction. Analysis demonstrates that the acoustic wave spreads cylindrically, that the sound intensity is highly directional, and that the sound pressure level increases significantly with increasing shock strength. The effect of shock strength on sound pressure level is consistent with experimental observations of shock noise, indicating that the interaction of a ring vortex with a shock wave correctly models a dominant mechanism of shock noise generation.

  11. Molecular modeling study on tunnel behavior in different histone deacetylase isoforms.

    Directory of Open Access Journals (Sweden)

    Sundarapandian Thangapandian

    Full Text Available Histone deacetylases (HDACs have emerged as effective therapeutic targets in the treatment of various diseases including cancers as these enzymes directly involved in the epigenetic regulation of genes. However the development of isoform-selective HDAC inhibitors has been a challenge till date since all HDAC enzymes possess conserved tunnel-like active site. In this study, using molecular dynamics simulation we have analyzed the behavior of tunnels present in HDAC8, 10, and 11 enzymes of class I, II, and IV, respectively. We have identified the equivalent tunnel forming amino acids in these three isoforms and found that they are very much conserved with subtle differences to be utilized in selective inhibitor development. One amino acid, methionine of HDAC8, among six tunnel forming residues is different in isoforms of other classes (glutamic acid (E in HDAC10 and leucine (L in HDAC 11 based on which mutations were introduced in HDAC11, the less studied HDAC isoform, to observe the effects of this change. The HDAC8-like (L268M mutation in the tunnel forming residues has almost maintained the deep and narrow tunnel as present in HDAC8 whereas HDAC10-like (L268E mutation has changed the tunnel wider and shallow as observed in HDAC10. These results explained the importance of the single change in the tunnel formation in different isoforms. The observations from this study can be utilized in the development of isoform-selective HDAC inhibitors.

  12. Chemical kinetics studies at high temperatures using shock tubes

    OpenAIRE

    Rajakumar, B; Anandraj, D; Reddy, KPJ; Arunan, E

    2002-01-01

    Shock tube is an unique facility to create temperature gradients exceeding million degrees Kelvin per second. We have established two shock tubes for measuring the kinetic reaction rates at high temperatures with two different but complementary detection techniques. The first one is a single pulse shock tube, in which the reflected shock is used to heat the molecules. The equilibrated products are analyzed by gas chromatograph and infrared spectrometer. The second one uses laser-schlieren sys...

  13. Inferring Pre-shock Acoustic Field From Post-shock Pitot Pressure Measurement

    Science.gov (United States)

    Wang, Jian-Xun; Zhang, Chao; Duan, Lian; Xiao, Heng; Virginia Tech Team; Missouri Univ of Sci; Tech Team

    2017-11-01

    Linear interaction analysis (LIA) and iterative ensemble Kalman method are used to convert post-shock Pitot pressure fluctuations to static pressure fluctuations in front of the shock. The LIA is used as the forward model for the transfer function associated with a homogeneous field of acoustic waves passing through a nominally normal shock wave. The iterative ensemble Kalman method is then employed to infer the spectrum of upstream acoustic waves based on the post-shock Pitot pressure measured at a single point. Several test cases with synthetic and real measurement data are used to demonstrate the merits of the proposed inference scheme. The study provides the basis for measuring tunnel freestream noise with intrusive probes in noisy supersonic wind tunnels.

  14. Analysis of an underground structure settlement risk due to tunneling- A case study from Tabriz, Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Vahdatirad

    2010-05-01

    Full Text Available The tunnel of the Tabriz urban railway line 2 (TURL2, Iran, will pass through an underground commercial center onits way. Too little distance between the tunnel crown and the underground structure foundation will probably cause collapseor excessive settlement during the tunnel construction based on studied geotechnical conditions of the region. In this paper,a method of risk level assessment for various types of structures, such as frame and masonry structures, and various typesof foundation, such as continuous and isolated, is well defined and the risk level is classified. Moreover, the value of theunderground commercial center structure settlement is estimated using both empirical and numerical methods. The settlementrisk level of the commercial center structure is determined based on presented definitions about risk classification ofvarious types of structures. Consequently, tunneling processes in this section need a special monitoring system and consolidationmeasures before the passage of a tunnel boring machine.

  15. Wind Tunnel Experiments to Study Chaparral Crown Fires.

    Science.gov (United States)

    Cobian-Iñiguez, Jeanette; Aminfar, AmirHessam; Chong, Joey; Burke, Gloria; Zuniga, Albertina; Weise, David R; Princevac, Marko

    2017-11-14

    The present protocol presents a laboratory technique designed to study chaparral crown fire ignition and spread. Experiments were conducted in a low velocity fire wind tunnel where two distinct layers of fuel were constructed to represent surface and crown fuels in chaparral. Chamise, a common chaparral shrub, comprised the live crown layer. The dead fuel surface layer was constructed with excelsior (shredded wood). We developed a methodology to measure mass loss, temperature, and flame height for both fuel layers. Thermocouples placed in each layer estimated temperature. A video camera captured the visible flame. Post-processing of digital imagery yielded flame characteristics including height and flame tilt. A custom crown mass loss instrument developed in-house measured the evolution of the mass of the crown layer during the burn. Mass loss and temperature trends obtained using the technique matched theory and other empirical studies. In this study, we present detailed experimental procedures and information about the instrumentation used. The representative results for the fuel mass loss rate and temperature filed within the fuel bed are also included and discussed.

  16. Study of tunneling transport in Si-based tunnel field-effect transistors with ON current enhancement utilizing isoelectronic trap

    Science.gov (United States)

    Mori, Takahiro; Morita, Yukinori; Miyata, Noriyuki; Migita, Shinji; Fukuda, Koichi; Mizubayashi, Wataru; Masahara, Meishoku; Yasuda, Tetsuji; Ota, Hiroyuki

    2015-02-01

    The temperature dependence of the tunneling transport characteristics of Si diodes with an isoelectronic impurity has been investigated in order to clarify the mechanism of the ON-current enhancement in Si-based tunnel field-effect transistors (TFETs) utilizing an isoelectronic trap (IET). The Al-N complex impurity was utilized for IET formation. We observed three types of tunneling current components in the diodes: indirect band-to-band tunneling (BTBT), trap-assisted tunneling (TAT), and thermally inactive tunneling. The indirect BTBT and TAT current components can be distinguished with the plot described in this paper. The thermally inactive tunneling current probably originated from tunneling consisting of two paths: tunneling between the valence band and the IET trap and tunneling between the IET trap and the conduction band. The probability of thermally inactive tunneling with the Al-N IET state is higher than the others. Utilization of the thermally inactive tunneling current has a significant effect in enhancing the driving current of Si-based TFETs.

  17. Interdot carrier's transfer via tunneling pathway studied from photoluminescence spectroscopy

    International Nuclear Information System (INIS)

    Rihani, J.; Sallet, V.; Yahyaoui, N.; Harmand, J.C.; Oueslati, M.; Chtourou, R.

    2009-01-01

    Self-assembled InAs quantum dots (QDs) on GaAs(0 0 1) substrate were grown by molecular beam epitaxy (MBE) at a growth temperature of 490 deg. C. Two different families of dots were observed in the atomic force microscopy (AFM) image and ambiguously identified in the photoluminescence (PL) spectra. Temperature-dependent PL study was carried out in the 8-270 K temperature range. The integrated-PL intensity behavior of the two QDs populations was fit with the help of a rate equations model. It is found that the evolutions of the integrated-PL intensity of the two QDs population were governed by two regimes. The first one occurs in the 8-210 K temperature range and reveals an unusual enhancement of the integrated-PL intensity of the larger QDs (LQDs) class. This was attributed to the carrier supplies from the smaller QDs (SQDs) class via the tunneling process. The second one occurs in the 210-270 K temperature range and shows a common quench of the PL signals of the two QDs families, reflecting the same thermal escape mechanism of carriers

  18. Success and failure of the defibrillation shock: insights from a simulation study.

    Science.gov (United States)

    Skouibine, K; Trayanova, N; Moore, P

    2000-07-01

    This simulation study presents a further inquiry into the mechanisms by which a strong electric shock fails to halt life-threatening cardiac arrhythmias. The research uses a model of the defibrillation process that represents a sheet of myocardium as a bidomain. The tissue consists of nonuniformly curved fibers in which spiral wave reentry is initiated. Monophasic defibrillation shocks are delivered via two line electrodes that occupy opposite tissue boundaries. In some simulation experiments, the polarity of the shock is reversed. Electrical activity in the sheet is compared for failed and successful shocks under controlled conditions. The maps of transmembrane potential and activation times calculated during and after the shock demonstrate that weak shocks fail to terminate the reentrant activity via two major mechanisms. As compared with strong shocks, weak shocks result in (1) smaller extension of refractoriness in the areas depolarized by the shock, and (2) slower or incomplete activation of the excitable gap created by deexcitation of the negatively polarized areas. In its turn, mechanism 2 is associated with one or more of the following events: (a) lack of some break excitations, (b) latency in the occurrence of the break excitations, and (c) slower propagation through deexcited areas. Reversal of shock polarity results in a change of the extent of the regions of deexcitation, and thus, in a change in defibrillation threshold. The results of this study indicate the paramount importance of shock-induced deexcitation in both defibrillation and postshock arrhythmogenesis.

  19. Geochemical study of acid mine drainage of the Big Lick Tunnel area, Williamstown, PA

    International Nuclear Information System (INIS)

    Tollin, S.

    1993-01-01

    Acid mine drainage in the anthracite region of Pennsylvania continues to be a significant environmental problem. This study examines the acid mine outflow from the Big Lick Tunnel, north of Williamstown, Dauphin County, Pennsylvania. The tunnel drains abandoned mines on the north side of the Big Lick Mountain. Mining ceased in the area circa 1940, and the tunnel has been in operation since that time. The water, soil and stream bed sediment geochemistry has been studied to determine their changes in chemistry over distance. The pH, TDS and metal concentrations were the primary focus. Metal concentrations were determined using an ICP unit. Data indicates the pH of the outflow to range between 6.7 and 7.3 Fe and Mn concentrations are as high as 9.7 ppb. Extensive metal precipitation (''yellow boy'') occurs within the tunnel and for several hundred meters from the mouth of the tunnel. The combination of near neutral pH and high metal concentration suggest that the drainage is in contact with highly alkaline materials prior to discharge from the tunnel. The geology of the area does not suggest bedrock as the possible source of alkaline material. One hypothesis is that the acidic water is reacting with the concrete tunnel and being neutralized. Data also suggests that the Fe precipitates much quicker than the Mn, resulting in a zonation between Fe-rich and Mn-rich sediments along the length of the drainage

  20. Reliability analysis of idealized tunnel support system using probability-based methods with case studies

    Science.gov (United States)

    Gharouni-Nik, Morteza; Naeimi, Meysam; Ahadi, Sodayf; Alimoradi, Zahra

    2014-06-01

    In order to determine the overall safety of a tunnel support lining, a reliability-based approach is presented in this paper. Support elements in jointed rock tunnels are provided to control the ground movement caused by stress redistribution during the tunnel drive. Main support elements contribute to stability of the tunnel structure are recognized owing to identify various aspects of reliability and sustainability in the system. The selection of efficient support methods for rock tunneling is a key factor in order to reduce the number of problems during construction and maintain the project cost and time within the limited budget and planned schedule. This paper introduces a smart approach by which decision-makers will be able to find the overall reliability of tunnel support system before selecting the final scheme of the lining system. Due to this research focus, engineering reliability which is a branch of statistics and probability is being appropriately applied to the field and much effort has been made to use it in tunneling while investigating the reliability of the lining support system for the tunnel structure. Therefore, reliability analysis for evaluating the tunnel support performance is the main idea used in this research. Decomposition approaches are used for producing system block diagram and determining the failure probability of the whole system. Effectiveness of the proposed reliability model of tunnel lining together with the recommended approaches is examined using several case studies and the final value of reliability obtained for different designing scenarios. Considering the idea of linear correlation between safety factors and reliability parameters, the values of isolated reliabilities determined for different structural components of tunnel support system. In order to determine individual safety factors, finite element modeling is employed for different structural subsystems and the results of numerical analyses are obtained in

  1. Case Study of Oriental Medicine Treatment with acupotomy Therpy of the Tarsal tunnel Syndrome

    Directory of Open Access Journals (Sweden)

    Lim Na-ra

    2009-03-01

    Full Text Available Purpose : In order to estimate clinical effects of Oriental Medicine Treatment with acupotomy therapy of Tarsal tunnel Syndrome Methods : From 5th November, 2008 to 8th November, 2008, 1 male patient diagnosed as Tarsal tunnel syndrome(clinical diagnosed was treated with general oriental medicine therapy (acupuncture, moxibustion, cupping, physical therapy, herbal medication and acupotomy. Results : The patient's Rt foot paresthesia, pain were remarkably improved. Conclusions : This study demonstrates that oriental medical treatment with acuputomy therapy has notable effect in improving symptoms of tarsal tunnel syndrome. as though we had not wide experience in this treatment, more research is needed.

  2. Study on the bearing capacity of embedded chute on shield tunnel segment

    Science.gov (United States)

    Fanzhen, Zhang; Jie, Bu; Zhibo, Su; Qigao, Hu

    2018-05-01

    The method of perforation and steel implantation is often used to fix and install pipeline, cables and other facilities in the shield tunnel, which would inevitably do damage to the precast segments. In order to reduce the damage and the resulting safety and durability problems, embedded chute was set at the equipment installation in one shield tunnel. Finite element models of segment concrete and steel are established in this paper. When water-soil pressure calculated separately and calculated together, the mechanical property of segment is studied. The bearing capacity and deformation of segment are analysed before and after embedding the chute. Research results provide a reference for similar shield tunnel segment engineering.

  3. A study of shock mitigating materials in a split Hopkinson bar configuration

    International Nuclear Information System (INIS)

    Bateman, V.I.; Bell, R.G. III; Brown, F.A.; Hansen, N.R.

    1996-01-01

    Sandia National Laboratories (SNL) designs mechanical systems with electronics that must survive high shock environments. These mechanical systems include penetrators that must survive soil, rock, and ice penetration, nuclear transportation casks that must survive transportation environments, and laydown weapons that must survive delivery impact of 125-fps. These mechanical systems contain electronics that may operate during and after the high shock environment and that must be protected from the high shock environments. A study has been started to improve the packaging techniques for the advanced electronics utilized in these mechanical systems because current packaging techniques are inadequate for these more sensitive electronics. In many cases, it has been found that the packaging techniques currently used not only do not mitigate the shock environment but actually amplify the shock environment. An ambitious goal for this packaging study is to avoid amplification and possibly attenuate the shock environment before it reaches the electronics contained in the various mechanical system. As part of the investigation of packaging techniques, a two part study of shock mitigating materials is being conducted. This paper reports the first part of the shock mitigating materials study. A study to compare three thicknesses (0.125, 0.250, and 0.500 in.) of seventeen, unconfined materials for their shock mitigating characteristics has been completed with a split Hopkinson bar configuration. The nominal input as measured by strain gages on the incident Hopkinson bar is 50 fps at sign 100 micros for these tests. It is hypothesized that a shock mitigating material has four purposes: to lengthen the shock pulse, to attenuate the shock pulse, to mitigate high frequency content in the shock pulse, and to absorb energy. Both time domain and frequency domain analyses of the split Hopkinson bar data have been performed to compare the materials' achievement of these purposes

  4. A Study of Vertical Transport through Graphene toward Control of Quantum Tunneling.

    Science.gov (United States)

    Zhu, Xiaodan; Lei, Sidong; Tsai, Shin-Hung; Zhang, Xiang; Liu, Jun; Yin, Gen; Tang, Min; Torres, Carlos M; Navabi, Aryan; Jin, Zehua; Tsai, Shiao-Po; Qasem, Hussam; Wang, Yong; Vajtai, Robert; Lake, Roger K; Ajayan, Pulickel M; Wang, Kang L

    2018-02-14

    Vertical integration of van der Waals (vdW) materials with atomic precision is an intriguing possibility brought forward by these two-dimensional (2D) materials. Essential to the design and analysis of these structures is a fundamental understanding of the vertical transport of charge carriers into and across vdW materials, yet little has been done in this area. In this report, we explore the important roles of single layer graphene in the vertical tunneling process as a tunneling barrier. Although a semimetal in the lateral lattice plane, graphene together with the vdW gap act as a tunneling barrier that is nearly transparent to the vertically tunneling electrons due to its atomic thickness and the transverse momenta mismatch between the injected electrons and the graphene band structure. This is accentuated using electron tunneling spectroscopy (ETS) showing a lack of features corresponding to the Dirac cone band structure. Meanwhile, the graphene acts as a lateral conductor through which the potential and charge distribution across the tunneling barrier can be tuned. These unique properties make graphene an excellent 2D atomic grid, transparent to charge carriers, and yet can control the carrier flux via the electrical potential. A new model on the quantum capacitance's effect on vertical tunneling is developed to further elucidate the role of graphene in modulating the tunneling process. This work may serve as a general guideline for the design and analysis of vdW vertical tunneling devices and heterostructures, as well as the study of electron/spin injection through and into vdW materials.

  5. Scanning tunneling microscopy studies of glucose oxidase on gold surface

    International Nuclear Information System (INIS)

    Losic, D.; Shapter, J.G.; Gooding, J.J.

    2002-01-01

    Full text: Three immobilization methods have been used for scanning tunneling microscopy (STM) studies of glucose oxidase (GOD) on gold. They are based on a) physical adsorption from solution, b) microcontact printing and c) covalent bonding onto self-assembled monolayers (SAM) of 3-mercaptopropionic acid (MPA). The STM images are used to provide information about the organization of individual GOD molecules and more densely packed monolayers of GOD on electrode surfaces, thus providing information of the role of interfacial structure on biosensor performance. The use of atomically flat gold substrates enables easy distinction of deposited enzyme features from the flat gold substrate. Microcontact printing is found to be a more reliable method than adsorption from solution for preparing individual GOD molecules on the gold surface STM images of printed samples reveal two different shapes of native GOD molecules. One is a butterfly shape with dimensions of 10 ± 1 nm x 6 ± 1 nm, assigned to the lying position of molecule while the second is an approximately spherical shape with dimensions of 6.5 ± 1 nm x 5 ± 1nm assigned to a standing position. Isolated clusters of 5 to 6 GOD molecules are also observed. With monolayer coverage, GOD molecules exhibit a tendency to organize themselves into a two dimensional array with adequate sample stability to obtain high-resolution STM images. Within these two-dimensional arrays are clearly seen repeating clusters of five to six enzyme molecules in a unit STM imaging of GOD monolayers covalently immobilized onto SAM (MPA) are considerably more difficult than when the enzyme is adsorbed directly onto the metal. Cluster structures are observed both high and low coverage despite the fact that native GOD is a negatively charged molecule. Copyright (2002) Australian Society for Electron Microscopy Inc

  6. Theoretical and Shock Tube Study of the Rate Constants for Hydrogen Abstraction Reactions of Ethyl Formate

    KAUST Repository

    Wu, Junjun; Khaled, Fathi; Ning, Hongbo; Ma, Liuhao; Farooq, Aamir; Ren, Wei

    2017-01-01

    We report a systematic chemical kinetics study of the H-atom abstractions from ethyl formate (EF) by H, O(3P), CH3, OH, and HO2 radicals. The geometry optimization and frequency calculation of all the species were conducted using the M06 method and the cc-pVTZ basis set. The one-dimensional hindered rotor treatment of the reactants and transition states and the intrinsic reaction coordinate analysis were also performed at the M06/cc-pVTZ level of theory. The relative electronic energies were calculated at the CCSD(T)/cc-pVXZ (where X = D, T) level of theory and further extrapolated to the complete basis set limit. Rate constants for the tittle reactions were calculated over the temperature range of 500‒2500 K by the transition state theory (TST) in conjunction with asymmetric Eckart tunneling effect. In addition, the rate constants of H-abstraction by hydroxyl radical were measured in shock tube experiments at 900‒1321 K and 1.4‒2.0 atm. Our theoretical rate constants of OH + EF → Products agree well with the experimental results within 15% over the experimental temperature range of 900‒1321 K. Branching ratios for the five types of H-abstraction reactions were also determined from their individual site-specific rate constants.

  7. Theoretical and Shock Tube Study of the Rate Constants for Hydrogen Abstraction Reactions of Ethyl Formate

    KAUST Repository

    Wu, Junjun

    2017-08-03

    We report a systematic chemical kinetics study of the H-atom abstractions from ethyl formate (EF) by H, O(3P), CH3, OH, and HO2 radicals. The geometry optimization and frequency calculation of all the species were conducted using the M06 method and the cc-pVTZ basis set. The one-dimensional hindered rotor treatment of the reactants and transition states and the intrinsic reaction coordinate analysis were also performed at the M06/cc-pVTZ level of theory. The relative electronic energies were calculated at the CCSD(T)/cc-pVXZ (where X = D, T) level of theory and further extrapolated to the complete basis set limit. Rate constants for the tittle reactions were calculated over the temperature range of 500‒2500 K by the transition state theory (TST) in conjunction with asymmetric Eckart tunneling effect. In addition, the rate constants of H-abstraction by hydroxyl radical were measured in shock tube experiments at 900‒1321 K and 1.4‒2.0 atm. Our theoretical rate constants of OH + EF → Products agree well with the experimental results within 15% over the experimental temperature range of 900‒1321 K. Branching ratios for the five types of H-abstraction reactions were also determined from their individual site-specific rate constants.

  8. General relativistic study of astrophysical jets with internal shocks

    Science.gov (United States)

    Vyas, Mukesh K.; Chattopadhyay, Indranil

    2017-08-01

    We explore the possibility of the formation of steady internal shocks in jets around black holes. We consider a fluid described by a relativistic equation of state, flowing about the axis of symmetry (θ = 0) in a Schwarzschild metric. We use two models for the jet geometry: (I) a conical geometry and (II) a geometry with non-conical cross-section. A jet with conical geometry has a smooth flow, while the jet with non-conical cross-section undergoes multiple sonic points and even standing shock. The jet shock becomes stronger, as the shock location is situated farther from the central black hole. Jets with very high energy and very low energy do not harbour shocks, but jets with intermediate energies do harbour shocks. One advantage of these shocks, as opposed to shocks mediated by external medium, is that these shocks have no effect on the jet terminal speed, but may act as possible sites for particle acceleration. Typically, a jet with specific energy 1.8c2 will achieve a terminal speed of v∞ = 0.813c for jet with any geometry, where, c is the speed of light in vacuum. But for a jet of non-conical cross-section for which the length scale of the inner torus of the accretion disc is 40rg, then, in addition, a steady shock will form at rsh ˜ 7.5rg and compression ratio of R ˜ 2.7. Moreover, electron-proton jet seems to harbour the strongest shock. We will discuss possible consequences of such a scenario.

  9. Studies on laser–plasma interaction physics for shock ignition

    Czech Academy of Sciences Publication Activity Database

    Maheut, Y.; Batani, D.; Nicolai, Ph.; Antonelli, L.; Krouský, Eduard

    2015-01-01

    Roč. 170, č. 4 (2015), s. 325-336 ISSN 1042-0150 EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Institutional support: RVO:68378271 Keywords : shock ignition * plasma * hot electrons * shocks * fusion Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 0.472, year: 2015

  10. Theoretical study of phosphorene tunneling field effect transistors

    International Nuclear Information System (INIS)

    Chang, Jiwon; Hobbs, Chris

    2015-01-01

    In this work, device performances of tunneling field effect transistors (TFETs) based on phosphorene are explored via self-consistent atomistic quantum transport simulations. Phosphorene is an ultra-thin two-dimensional (2-D) material with a direct band gap suitable for TFETs applications. Our simulation shows that phosphorene TFETs exhibit subthreshold slope below 60 mV/dec and a wide range of on-current depending on the transport direction due to highly anisotropic band structures of phosphorene. By benchmarking with monolayer MoTe 2 TFETs, we predict that phosphorene TFETs oriented in the small effective mass direction can yield much larger on-current at the same on-current/off-current ratio than monolayer MoTe 2 TFETs. It is also observed that a gate underlap structure is required for scaling down phosphorene TFETs in the small effective mass direction to suppress the source-to-drain direct tunneling leakage current

  11. Theoretical study of phosphorene tunneling field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jiwon; Hobbs, Chris [SEMATECH, 257 Fuller Rd #2200, Albany, New York 12203 (United States)

    2015-02-23

    In this work, device performances of tunneling field effect transistors (TFETs) based on phosphorene are explored via self-consistent atomistic quantum transport simulations. Phosphorene is an ultra-thin two-dimensional (2-D) material with a direct band gap suitable for TFETs applications. Our simulation shows that phosphorene TFETs exhibit subthreshold slope below 60 mV/dec and a wide range of on-current depending on the transport direction due to highly anisotropic band structures of phosphorene. By benchmarking with monolayer MoTe{sub 2} TFETs, we predict that phosphorene TFETs oriented in the small effective mass direction can yield much larger on-current at the same on-current/off-current ratio than monolayer MoTe{sub 2} TFETs. It is also observed that a gate underlap structure is required for scaling down phosphorene TFETs in the small effective mass direction to suppress the source-to-drain direct tunneling leakage current.

  12. Comparative Study between Slow Shock Wave Lithotripsy and Fast Shock Wave Lithotripsy in the Management of Renal Stone

    Directory of Open Access Journals (Sweden)

    AKM Zamanul Islam Bhuiyan

    2013-01-01

    Full Text Available Background: Renal calculi are frequent causes of ureteric colic. Extracorporeal shock wave lithotripsy is the most common treatment of these stones. It uses focused sound waves to break up stones externally. Objective: To compare the efficiency of slow and fast delivery rate of shock waves on stone fragmentation and treatment outcome in patients with renal calculi. Materials and Methods: This prospective study was done in the department of Urology, National Institute of Kidney diseases and Urology, Sher-e-Bangla Nagar, Dhaka from July 2006 to June 2007. Total 90 patients were treated using the Storz Medical Modulith ® SLX lithotripter. Patients were divided into Group A, Group B and Group C – each group having 30 subjects. Group A was selected for extracorporeal shockwave lithotripsy (ESWL by 60 shock waves per minute, Group B by 90 shock waves per minute and Group C by 120 shock waves per minute. Results: Complete clearance of stone was observed in 24 patients in Group A and 13 patients in both Group B and Group C in first session. In Group A only 3 patients needed second session but in Group B and Group C, 12 and 8 patients needed second session. In Group A only one patient needed third session but third session was required for 3 patients in Group B and 5 patients in Group C for complete clearance of stone. In Group A, subsequent sessions were performed under spinal anesthesia and in Group B under sedation and analgesia (p>0.001. Mean number of sessions for full clearance of stones in group A was 1.37 ± 0.85, in Group B was 1.8 ± 0.887 and in Group C was 2.0 ± 1.083. Significant difference was observed in term of sessions among groups (p>0.05. In first follow-up, complete clearance of stones was seen in 24 patients in Group A and 13 in both Group B and Group C. In second follow-up, 3 patients in Group A, 12 in Group B and 8 in Group C showed complete clearance of stones. It was observed that rate of stone clearance was higher in Group A

  13. In situ stresses in rock masses: methodology for its study in tunnel projects in Spain

    International Nuclear Information System (INIS)

    Madirolas Perez, G.; Perucho Martinez, A.

    2014-01-01

    In situ stress is one of the main factors to be taken into account in the design of tunnels, as it can cause inadmissible stresses and strains leading to high deviations in the budgets. For that reason, the stress state is directly introduced into the numerical models used for the design of tunnels. In Spain, although several tunnels have been carried out with an important overburden in tectonically relevant zones, a quantitative determination of the stresses has not been usually included in civil work projects. Therefore, it is considered necessary to implement a routine procedure of study of civil work projects involving tunnels excavated in rock, and a new detailed methodology is proposed. The challenge is that project managers, who face works in which stresses may play a determinant role, may have a practical reference enabling them to optimize available resources and to include the real stress information in the design of underground works. (Author)

  14. Air pollution at an urban traffic tunnel in Lisbon, Portugal-an INAA study

    Energy Technology Data Exchange (ETDEWEB)

    Almeida-Silva, M.; Canha, N. [Instituto Tecnologico e Nuclear, URSN, E.N. 10, 2686-953 Sacavem (Portugal); Freitas, M.C., E-mail: cfreitas@itn.pt [Instituto Tecnologico e Nuclear, URSN, E.N. 10, 2686-953 Sacavem (Portugal); Dung, H.M; Dionisio, I. [Instituto Tecnologico e Nuclear, URSN, E.N. 10, 2686-953 Sacavem (Portugal)

    2011-11-15

    In this study, the results of chemical concentrations inside and outside of a Lisbon (Portugal) traffic tunnel were compared, during one week. They were obtained by Instrumental Neutron Activation Analysis (INAA). The tunnel values largely exceed the Air Ambient legislated values and the Pearson Correlations Coefficients point out to soil re-suspension/dispersed road dust (As, Ce, Eu, Hf, Fe, Mo, Sc, Zn), traffic-markers (Ba, Cr), tire wear (Cr, Zn), break wear (Fe, Zn, Ba, Cu, Sb), exhaust and motor oil (Zn) and sea-spray (Br, Na). On all days these elements inside the tunnel were more enriched than outside; significant statistical differences were found for Co (p=0.005), Br (p=0.008), Zn (p=0.01) and Sb (p=0.005), while enrichment factors of As and Sc are statistically identical. The highest values were found for As, Br, Zn and Sb, for both inside and outside the tunnel.

  15. Gate-controlled current and inelastic electron tunneling spectrum of benzene: a self-consistent study.

    Science.gov (United States)

    Liang, Y Y; Chen, H; Mizuseki, H; Kawazoe, Y

    2011-04-14

    We use density functional theory based nonequilibrium Green's function to self-consistently study the current through the 1,4-benzenedithiol (BDT). The elastic and inelastic tunneling properties through this Au-BDT-Au molecular junction are simulated, respectively. For the elastic tunneling case, it is found that the current through the tilted molecule can be modulated effectively by the external gate field, which is perpendicular to the phenyl ring. The gate voltage amplification comes from the modulation of the interaction between the electrodes and the molecules in the junctions. For the inelastic case, the electron tunneling scattered by the molecular vibrational modes is considered within the self-consistent Born approximation scheme, and the inelastic electron tunneling spectrum is calculated.

  16. Wound shock: a history of its study and treatment by military surgeons.

    Science.gov (United States)

    Hardaway, Robert M

    2004-04-01

    The treatment of wounds has received considerable attention from the time of the Trojan War. However, it was not until the American Civil War that shock was described as an entity distinct from the wounds themselves and that efforts were directed at more than just treatment of the wound. The need for fluid resuscitation in the treatment of hemorrhagic shock was first recognized in the Spanish American War, as was the association of sepsis with shock. World War I showed the need for blood in the treatment of "wound shock," a lesson that had to be relearned in World War II through bitter experience. Studies in the Korean War described the concept of disseminated intravascular coagulation and multiple organ failure, and the existence of disseminated intravascular coagulation was confirmed by studies in Vietnam. The treatment of hemorrhagic shock is now very effective, but the treatment of traumatic and septic shock remains unsatisfactory.

  17. Numerical Study of Shock-Cylinder Banks Interactions

    International Nuclear Information System (INIS)

    Wang, S.P.; Anderson, M.H.; Oakley, J.G.; Bonazza, R.

    2003-01-01

    A numerical parametric study of shock-cylinder banks interactions is presented using a high resolution Euler solver. Staggered cylinder banks of five rows are chosen with the purpose of modeling IFE reactor cooling tube banks. The effect of the aspect ratio of the intercylinder pitch to the distance between successive cylinder rows on the vertical pressure forces acting on the cylinders with different geometries is investigated. Preliminary results show that the largest vertical force develops on the cylinders of the second or third row. This peak pressure force increases with decreasing values of the aspect ratio. It is shown that an increasing second force peak also appears on the successive rows, starting with the second one, with decreasing aspect ratio. It is also observed that the force on the last-row cylinders basically decreases to the level of that on the first row. The results are useful for the optimal design of the cooling tubes system of IFE reactors

  18. Molecular dynamics study of shock compression in porous silica glass

    Science.gov (United States)

    Jones, Keith; Lane, J. Matthew D.; Vogler, Tracy J.

    2017-06-01

    The shock response of porous amorphous silica is investigated using classical molecular dynamics, over a range of porosity ranging from fully dense (2.21 g/cc) down to 0.14 g/cc. We observe an enhanced densification in the Hugoniot response at initial porosities above 50 %, and the effect increases with increasing porosity. In the lowest initial densities, after an initial compression response, the systems expand with increased pressure. These results show good agreement with experiments. Mechanisms leading to enhanced densification will be explored, which appear to differ from mechanisms observed in similar studies in silicon. Sandia National Laboratories is a multi mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  19. First Principles Study of Electron Tunneling through Ice

    KAUST Repository

    Cucinotta, Clotilde S.

    2012-10-25

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

  20. Tunneling study of SRF cavity-grade niobium

    International Nuclear Information System (INIS)

    Proslier, T.; Zasadzinski, J.; Cooley, L.; Pellin, M.; Norem, J.; Elam, J.; Antonine, C. Z.; Rimmer, R.; Kneisel, P.

    2009-01-01

    Niobium, with its very high H C1 , has been used in superconducting radio frequency (SRF) cavities for accelerator systems for 40 years with continual improvement. The quality factor of cavities (Q) is governed by the surface impedance R BCS , which depends on the quasiparticle gap, delta, and the superfluid density. Both of these parameters are seriously affected by surface imperfections (metallic phases, dissolved oxygen, magnetic impurities). Loss mechanism and surface treatments of Nb cavities found to improve the Q factor are still unsolved mysteries. We present here an overview of the capabilities of the point contact tunneling spectroscopy and Atomic layer deposition methods and how they can help understanding the High field Q-drop and the mild baking effect. Tunneling spectroscopy was performed on Nb pieces from the same processed material used to fabricate SRF cavities. Air exposed, electropolished Nb exhibited a surface superconducting gap Delta = 1.55 meV, characteristic of clean, bulk Nb, however the tunneling density of states (DOS) was broadened significantly. Nb pieces treated with the same mild baking used to improve the Q-slope in SRF cavities revealed a much sharper DOS. Good fits to the DOS are obtained using Shiba theory suggesting that magnetic scattering of quasiparticles is the origin of the degraded surface superconductivity and the Q-slope problem of Nb SRF cavities

  1. First Principles Study of Electron Tunneling through Ice

    KAUST Repository

    Cucinotta, Clotilde S.; Rungger, Ivan; Sanvito, Stefano

    2012-01-01

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

  2. Tunneling technologies for the collider ring tunnels

    International Nuclear Information System (INIS)

    Frobenius, P.

    1989-01-01

    The Texas site chosen for the Superconducting Super Collider has been studied, and it has been determined that proven, conventional technology and accepted engineering practice are suitable for constructing the collider tunnels. The Texas National Research Laboratory Commission report recommended that two types of tunneling machines be used for construction of the tunnels: a conventional hard rock tunnel boring machine (TBM) for the Austin chalk and a double shielded, rotary TBM for the Taylor marl. Since the tunneling machines usually set the pace for the project, efficient planning, operation, and coordination of the tunneling system components will be critical to the schedule and cost of the project. During design, tunneling rate prediction should be refined by focusing on the development of an effective tunneling system and evaluating its capacity to meet or exceed the required schedules. 8 refs., 13 figs

  3. Study of the shock ignition scheme in inertial confinement fusion

    International Nuclear Information System (INIS)

    Lafon, M.

    2011-01-01

    The Shock Ignition (SI) scheme is an alternative to classical ignition schemes in Inertial Confinement Fusion. Its singularity relies on the relaxation of constraints during the compression phase and fulfilment of ignition conditions by launching a short and intense laser pulse (∼500 ps, ∼300 TW) on the pre-assembled fuel at the end of the implosion.In this thesis, it has been established that the SI process leads to a non-isobaric fuel configuration at the ignition time thus modifying the ignition criteria of Deuterium-Tritium (DT) against the conventional schemes. A gain model has been developed and gain curves have been inferred and numerically validated. This hydrodynamical modeling has demonstrated that the SI process allows higher gain and lower ignition energy threshold than conventional ignition due to the high hot spot pressure at ignition time resulting from the ignitor shock propagation.The radiative hydrodynamic CHIC code developed at the CELIA laboratory has been used to determine parametric dependences describing the optimal conditions for target design leading to ignition. These numerical studies have enlightened the potential of SI with regards to saving up laser energy, obtain high gains but also to safety margins and ignition robustness.Finally, the results of the first SI experiments performed in spherical geometry on the OMEGA laser facility (NY, USA) are presented. An interpretation of the experimental data is proposed from mono and bidimensional hydrodynamic simulations. Then, different trails are explored to account for the differences observed between experimental and numerical data and alternative solutions to improve performances are suggested. (author) [fr

  4. DSMC simulations of shock interactions about sharp double cones

    Science.gov (United States)

    Moss, James N.

    2001-08-01

    This paper presents the results of a numerical study of shock interactions resulting from Mach 10 flow about sharp double cones. Computations are made by using the direct simulation Monte Carlo (DSMC) method of Bird. The sensitivity and characteristics of the interactions are examined by varying flow conditions, model size, and configuration. The range of conditions investigated includes those for which experiments have been or will be performed in the ONERA R5Ch low-density wind tunnel and the Calspan-University of Buffalo Research Center (CUBRC) Large Energy National Shock (LENS) tunnel.

  5. EXPERIMENTAL STUDY ON THE STABILITY OF SURROUNDING ROCK IN TUNNEL BLASTING CONSTRUCTION

    Directory of Open Access Journals (Sweden)

    Hongxian Fu

    2018-04-01

    Full Text Available In this study, criteria and blasting technologies are introduced in order to control the stability of surrounding rock of tunnel built using drill-and-blast safety. The paper is composed of three parts, namely, a blast vibration propagation law in roof surrounding rock in close proximity to tunnel face, two formulae to calculate particle critical vibration velocity of shotcrete and key structural element at the roof of tunnel, and innovative technologies of tunnel blasting. The blast vibration propagation law is the base to control the stability of surrounding rock during tunnel blasting. Based on Morhr-Coulomb criterion and the dynamic analysis, two formulae to calculate the critical particle vibration velocity are proposed. Based on a series of trial blasts using electronic detonators, two innovative blasting technologies are derived. One is the blast holes detonated one by one by using electronic detonator, and another is the blast holes detonated by combining initiation system of electronic detonators and nonel detonators. The use of electronic detonators in tunnel blasting not only leads to a smaller blast vibration but also to a smaller extent of the EDZ (excavation damaged zone.

  6. Two-dimensional study of shock breakout at the rear face of laser irradiated metallic targets

    Energy Technology Data Exchange (ETDEWEB)

    Cottet, F.; Marty, L.; Hallouin, M.; Romain, J.P.; Virmont, J.; Fabbro, R.; Faral, B.

    1988-11-01

    The two-dimensional propagation dynamics of laser-driven shock waves in solids is studied through the analysis of the shock breakout at the rear face of the target for a set of materials and laser intensities. The laser shock simulations were carried out by means of a two-dimensional hydrodynamics code in which the laser-ablation pressure is replaced by an equivalent pressure pulse. It is shown that the two-dimensional code is a very useful tool to analyze laser-shock experiments where two-dimensional effects arise from a finite laser-spot size or a heterogeneous energy deposition.

  7. Two-dimensional study of shock breakout at the rear face of laser irradiated metallic targets

    International Nuclear Information System (INIS)

    Cottet, F.; Marty, L.; Hallouin, M.; Romain, J.P.; Virmont, J.; Fabbro, R.; Faral, B.

    1988-01-01

    The two-dimensional propagation dynamics of laser-driven shock waves in solids is studied through the analysis of the shock breakout at the rear face of the target for a set of materials and laser intensities. The laser shock simulations were carried out by means of a two-dimensional hydrodynamics code in which the laser-ablation pressure is replaced by an equivalent pressure pulse. It is shown that the two-dimensional code is a very useful tool to analyze laser-shock experiments where two-dimensional effects arise from a finite laser-spot size or a heterogeneous energy deposition

  8. Simulating Small-Scale Experiments of In-Tunnel Airblast Using STUN and ALE3D

    Energy Technology Data Exchange (ETDEWEB)

    Neuscamman, Stephanie [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glenn, Lewis [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schebler, Gregory [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McMichael, Larry [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glascoe, Lee [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-09-12

    This report details continuing validation efforts for the Sphere and Tunnel (STUN) and ALE3D codes. STUN has been validated previously for blast propagation through tunnels using several sets of experimental data with varying charge sizes and tunnel configurations, including the MARVEL nuclear driven shock tube experiment (Glenn, 2001). The DHS-funded STUNTool version is compared to experimental data and the LLNL ALE3D hydrocode. In this particular study, we compare the performance of the STUN and ALE3D codes in modeling an in-tunnel airblast to experimental results obtained by Lunderman and Ohrt in a series of small-scale high explosive experiments (1997).

  9. Electroluminescence from single nanowires by tunnel injection: an experimental study

    International Nuclear Information System (INIS)

    Zimmler, Mariano A; Bao Jiming; Shalish, Ilan; Yi, Wei; Yoon, Joonah; Narayanamurti, Venkatesh; Capasso, Federico

    2007-01-01

    We present a hybrid light-emitting diode structure composed of an n-type gallium nitride nanowire on a p-type silicon substrate in which current is injected along the length of the nanowire. The device emits ultraviolet light under both bias polarities. Tunnel injection of holes from the p-type substrate (under forward bias) and from the metal (under reverse bias) through thin native oxide barriers consistently explains the observed electroluminescence behaviour. This work shows that the standard p-n junction model is generally not applicable to this kind of device structure

  10. High-temperature magnetoresistance study of a magnetic tunnel junction

    International Nuclear Information System (INIS)

    Chen, D.C.; Yao, Y.D.; Chen, C.M.; Hung, James; Chen, Y.S.; Wang, W.H.; Chen, W.C.; Kao, M.J.

    2006-01-01

    The thermal stability and the spin transportation phenomenon at room temperature and 140 deg. C of a series of magnetic tunneling junctions with the structure of bottom electrode/PtMn/Pinned layer/ AlO x /CoFe/NiFe/top electrode have been investigated. The MR ratio decreases from 33.5% at room temperature to 29% at 140 deg. C. The MR ratio at room temperature increases roughly 0.8% after thermal treatment at temperatures above 60 deg. C. This is related to the thermal relaxation of the strains existing in the samples

  11. Radioisotopic studies on pulmonary function in experimental burn shock

    International Nuclear Information System (INIS)

    Lambrecht, W.; Barcikowski, S.; Maziarz, Z.; Zajgner, J.; Markiewicz, A.

    1980-01-01

    Disturbances in pulmonary ventilation and perfusion, which can initiate severe complications, often lead to many therapeutic failures in burn shock. Early recognition of respiratory disturbances is often required to improve results of treatment of burn shock. The authors investigated changes in pulmonary ventilation and perfusion in napalm-burnt rabbits using 133 Xe. Simultaneously, they determined effect of treatment with cytochrome C on pulmonary ventilation and perfusion in animals burnt with napalm. It was found that in napalm-burnt rabbits burn shock was accompanied by a significant deterioration in pulmonary ventilation and perfusion. The most marked changes were observed one and two days after burn. It was also found a beneficial effect of treatment with cytochrome C on alveolar ventilation. The authors pointed out the usefulness of radioisotopic investigations of pulmonary ventilation and perfusion in burn shock. (author)

  12. Computational Study of Shock-Associated Noise Characteristics Using LES

    Science.gov (United States)

    2014-10-03

    REFERENCES [1] Harper-Bourne, M., and Fisher, M. J., “The Noise from Shock Waves in Supersonic Jets,” AGARD - CP -131, 1973, pp. 1-13. [2] Tam, C. K...J. M., “Broadband Shock Noise from Supersonic Jets,” AIAA Journal, Volume 20, No. 1, 1982, pp. 68- 73 . [9] Seiner, J. M., “Advances in High Speed

  13. Simulation Study of Shock Reaction on Porous Material

    International Nuclear Information System (INIS)

    Xu Aiguo; Zhang Guangcai; Pan Xiaofei; Zhu Jianshi

    2009-01-01

    Direct modeling of porous materials under shock is a complex issue. We investigate such a system via the newly developed material-point method. The effects of shock strength and porosity size are the main concerns. For the same porosity, the effects of mean-void-size are checked. It is found that local turbulence mixing and volume dissipation are two important mechanisms for transformation of kinetic energy to heat. When the porosity is very small, the shocked portion may arrive at a dynamical steady state; the voids in the downstream portion reflect back rarefactive waves and result in slight oscillations of mean density and pressure; for the same value of porosity, a larger mean-void-size makes a higher mean temperature. When the porosity becomes large, hydrodynamic quantities vary with time during the whole shock-loading procedure: after the initial stage, the mean density and pressure decrease, but the temperature increases with a higher rate. The distributions of local density, pressure, temperature and particle-velocity are generally non-Gaussian and vary with time. The changing rates depend on the porosity value, mean-void-size and shock strength. The stronger the loaded shock, the stronger the porosity effects. This work provides a supplement to experiments for the very quick procedures and reveals more fundamental mechanisms in energy and momentum transportation. (general)

  14. Elastic-plastic fracture mechanics study of thermal shock cracking

    International Nuclear Information System (INIS)

    Hirano, K.; Kobayashi, H.; Nakazawa, H.

    1980-01-01

    This paper describes thermal shock experiments conducted on a nuclear pressure vessel steel (A533 Grade B Class 1), an AISI304 steel and a tool steel (JIS SKD62) using both a new thermal shock test facility and method. Analysis of their quasi-static thermal stress intensity factors is performed on the basis of linear-elastic fracture mechanics; and a thermal shock fracture toughness value, Ksub(tsc) is evaluated. Then elastic-plastic fracture toughness tests are carried out in the same high temperature range of the thermal shock experiment, and a relation between the stretched zone width, SZW, formed as a result of the fatigue precrack tip plastic blunting and the J-integral is clarified. An elastic-plastic thermal shock fracture toughness value, Jsub(tsc), is evaluated from a critical value of the stretched zone width, SZWsub(tsc), at the initiation of the thermal shock cracking by using the relation between SZW and J. The Jsub(tsc) value is compared with an elastic-plastic fracture toughness value, Jsub(Ic), and the difference between these Jsub(tsc) and Jsub(Ic) values is discussed on the basis of fractography. (author)

  15. Study and fabrication of tunnel diodes made on germanium using a collective planar technique

    International Nuclear Information System (INIS)

    Vrahides, Michel

    1973-01-01

    The main results of the theory on tunnel diodes are presented in the first chapter. From these results are deduced the technological requirements that any fabrication process should meet to make tunnel diodes. These requirements show up that, among the three techniques for junction making (thermal diffusion of impurities, epitaxy, alloying), the last one is presently the best fitted to the fabrication of tunnel junctions. By analyzing the defects created by various alloying technologies presently used, together with a study of the benefits due to a use of chemical photolithography, evaporation under vacuum and masking by deposited oxide, it is possible to design a tentative scheme of a 0.5 ns tunnel diode. Then, in a second chapter, is presented the collective process for fabrication that has been used on monocrystalline, P-type, germanium wafers. 8 000 tunnel diodes may be positioned on a 1.5 inch diameter wafer by using that process. A description of the various apparatus used is also given. The experimental results are described in the third chapter. The influence of the various fabrication parameters on the electrical characteristics of the diodes are discussed. It is shown, by studying the fabrication yields and parameter spreading, that 80 per cent of the diodes exhibit a standard tunnel diode behaviour and that 90 per cent of these present a peak current dispersion less than ± 25 per cent. When measuring at the peak current drifts under temperature stresses, a good analogy with conventional tunnel diode is found. Some measurements of switching times have led to values as low as 0.6 nanoseconds. (author) [fr

  16. Thermal shock studies associated with injection of emergency core coolant in pressurized water reactors

    International Nuclear Information System (INIS)

    Cheverton, R.D.; Bolt, S.E.; Iskander, S.K.

    1977-01-01

    Studies to determine the accuracy of calculational techniques for predicting crack initiation and arrest in PWR vessels due to thermal shock from ECC injection are described. The reference calculational model is reviewed, the experimental program and facilities are described, and some thermal shock experiments and results are discussed

  17. Shock-tube study of fusion plasma-wall interactions

    International Nuclear Information System (INIS)

    Gross, R.A.; Tien, J.K.; Jensen, B.; Panayotou, N.F.; Feinberg, B.

    1977-01-01

    Theoretical and experimental studies have been made of phenomena which occur when a hot (T 1 approximately equal to 6 x 10 6 0 K), dense (n approximately equal to 10 16 cm -3 ), deuterium plasma containing a transverse magnetic field is brought into sudden contact with a cold metal wall. These studies are motivated by the need to understand plasma and metallurgical conditions at the first-wall of a fusion reactor. Experiments were carried out in the Columbia high energy electromagnetic shock tube. Computational simulation was used to investigate the detailed physics of the fusion plasma boundary layer which develops at the wall. The rate of energy transfer from the plasma to the wall was calculated and conditions under which surface melting occurs are estimated. Experimental measurements of plasma-wall heat transfer rates up to 3 x 10 5 watts/cm 2 were obtained and agreement with computed values are good. Fusion reactor first-wall materials have been exposed to 6.0 x 10 21 eV cm -2 (1,000 shots) of deuterium plasma bombardment. Scanning electron micrograph photographs show preferential erosion at grain boundaries, formation of deuterium surface blisters, and evidence of local surface melting. Some cracking is observed along grain boundaries, and a decrease in tensile ductiity is measured

  18. A study of surface diffusion with the scanning tunneling microscope from fluctuations of the tunneling current

    Energy Technology Data Exchange (ETDEWEB)

    Manuel, Lozano [Iowa State Univ., Ames, IA (United States)

    1996-01-12

    The transport of atoms or molecules over surfaces has been an important area of study for several decades now, with its progress generally limited by the available experimental techniques to characterize the phenomena. A number of methods have been developed over the years to measure surface diffusion yet only very few systems have been characterized to this day mainly due to the physical limitations inherent in these available methods. Even the STM with its astonishing atomically-resolved images of the surface has been limited in terms of its capability to determine mass transport properties. This is because the STM is inherently a ``slow`` instrument, i.e., a finite time is needed for signal averaging in order to produce the image. A need exists for additional surface diffusion measurement techniques, ideally ones which are able to study varied systems and measure a wide range of diffusion rates. The STM (especially because of its highly local nature) presents itself as a promising tool to conduct dynamical studies if its poor time resolution during ``normal operation`` can somehow be overcome. The purpose of this dissertation is to introduce a new technique of using the STM to measure adatom mobility on surfaces -- one with a capacity to achieve excellent time resolution.

  19. Do dividend shocks affect excess returns? An experimental study

    Directory of Open Access Journals (Sweden)

    Draganac Dragana

    2017-01-01

    Full Text Available The dividend announcement of a company is an informational event that can cause underreaction, momentum, overreaction, post-dividend announcement drift, and mean reversion. It is the uncertainty surrounding dividend announcements that leads to such behavioural phenomena. Most authors consider that underreaction occurs after dividend shocks because new information about the dividend is being slowly and gradually built into the stock price. The effect of dividend shocks is often reflected in excess returns, which can last up to one year after the shock. The experiment described in this paper tests whether statistically significant excess returns are realized after a shock dividend announcement. Participants trade with the stocks of two companies, which only differ by dividend-generating stochastic process. The dividend process of Company 2 is a Merton-style jump-diffusion process (consisting of two parts: Brownian motion and Poisson jump, while the dividend process of Company 1 contains only the Brownian motion component. Statistically significant excess returns are expected when trading with Company 2 stocks. An autoregressive model is applied in order to test this hypothesis. The conclusion is that a dividend shock is followed by statistically significant excess returns in 20 of the 22 experiments, which implies that markets are inefficient after sudden and large changes in dividends. Underreaction and discount rate effects are identified.

  20. Note: long-range scanning tunneling microscope for the study of nanostructures on insulating substrates.

    Science.gov (United States)

    Molina-Mendoza, Aday J; Rodrigo, José G; Island, Joshua; Burzuri, Enrique; Rubio-Bollinger, Gabino; van der Zant, Herre S J; Agraït, Nicolás

    2014-02-01

    The scanning tunneling microscope (STM) is a powerful tool for studying the electronic properties at the atomic level, however, it is of relatively small scanning range and the fact that it can only operate on conducting samples prevents its application to study heterogeneous samples consisting of conducting and insulating regions. Here we present a long-range scanning tunneling microscope capable of detecting conducting micro and nanostructures on insulating substrates using a technique based on the capacitance between the tip and the sample and performing STM studies.

  1. Note: Long-range scanning tunneling microscope for the study of nanostructures on insulating substrates

    Energy Technology Data Exchange (ETDEWEB)

    Molina-Mendoza, Aday J., E-mail: aday.molina@uam.es [Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Campus de Cantoblanco, E-28049 Madrid (Spain); Rodrigo, José G.; Rubio-Bollinger, Gabino [Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Campus de Cantoblanco, E-28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC) and Instituto Universitario de Ciencia de Materiales “Nicolás Cabrera,” Universidad Autónoma de Madrid, Campus de Cantoblanco, E-28049 Madrid (Spain); Island, Joshua; Burzuri, Enrique; Zant, Herre S. J. van der [Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft (Netherlands); Agraït, Nicolás [Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Campus de Cantoblanco, E-28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC) and Instituto Universitario de Ciencia de Materiales “Nicolás Cabrera,” Universidad Autónoma de Madrid, Campus de Cantoblanco, E-28049 Madrid (Spain); Instituto Madrileño de Estudios Avanzados en Nanociencia IMDEA-Nanociencia, E-28049 Madrid (Spain)

    2014-02-15

    The scanning tunneling microscope (STM) is a powerful tool for studying the electronic properties at the atomic level, however, it is of relatively small scanning range and the fact that it can only operate on conducting samples prevents its application to study heterogeneous samples consisting of conducting and insulating regions. Here we present a long-range scanning tunneling microscope capable of detecting conducting micro and nanostructures on insulating substrates using a technique based on the capacitance between the tip and the sample and performing STM studies.

  2. Potential risks at an industrial site: A wind tunnel study

    Czech Academy of Sciences Publication Activity Database

    Jaňour, Zbyněk; Jurčáková, Klára; Brych, Karel; Dittrt, František; Dittrich, F.

    2010-01-01

    Roč. 88, č. 3 (2010), s. 185-190 ISSN 0957-5820 R&D Projects: GA MŠk(CZ) OC 113 Institutional research plan: CEZ:AV0Z20760514; CEZ:AV0Z20600510 Keywords : atmospheric turbulence * flow visualization * wind tunnel modeling Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.453, year: 2010 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B8JGG-4Y7P8YF-1&_user=640952&_coverDate=05%2F31%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1433050901&_rerunOrigin= google &_acct=C000034318&_version=1&_urlVersion=0&_userid=640952&md5=b036d2c5d747eadc03ff5697ea45e6a2

  3. Molecules on vicinal Au surfaces studied by scanning tunnelling microscopy

    International Nuclear Information System (INIS)

    Kroeger, J; Neel, N; Jensen, H; Berndt, R; Rurali, R; Lorente, N

    2006-01-01

    Using low-temperature scanning tunnelling microscopy and spectroscopy we investigated the adsorption characteristics of 3,4,9,10-perylenetetracarboxylic-dianhydride and fullerenes on Au(788), Au(433), and Au(778). On Au(788) and Au(778), 3,4,9,10-perylenetetracarboxylic-dianhydride exhibits three coexisting superstructures, which do not reflect the periodicity of the hosting substrate. The adsorption on Au(433) leads to the formation of molecule chains along the step edges after annealing the sample. Fullerene molecules on Au(788) arrange in a mesh of islands, which extends over several hundreds of nanometres with an extraordinarily high periodicity. A combination of fullerene adsorption and annealing leads to facetting of Au(433) and the formation of extraordinarily long fullerene stripes

  4. A study of shock mitigating materials in a split Hopkinson bar configuration. Phase 1

    International Nuclear Information System (INIS)

    Bateman, V.I.; Brown, F.A.; Hansen, N.R.

    1998-06-01

    Sandia National Laboratories (SNL) designs mechanical systems with electronics that must survive high shock environments. These mechanical systems include penetrators that must survive soil, rock, and ice penetration, nuclear transportation casks that must survive transportation environments, and laydown weapons that must survive delivery impact of 125 fps. These mechanical systems contain electronics that may operate during and after the high shock environment and that must be protected from the high shock environments. A study has been started to improve the packaging techniques for the advanced electronics utilized in these mechanical systems because current packaging techniques are inadequate for these more sensitive electronics. In many cases, it has been found that the packaging techniques currently used not only do not mitigate the shock environment but actually amplify the shock environment. An ambitious goal for this packaging study is to avoid amplification and possibly attenuate the shock environment before it reaches the electronics contained in the various mechanical systems. As part of the investigation of packaging techniques, a two phase study of shock mitigating materials is being conducted. The purpose of the first phase reported here is to examine the performance of a joint that consists of shock mitigating material sandwiched in between steel and to compare the performance of the shock mitigating materials. A split Hopkinson bar experimental configuration simulates this joint and has been used to study the shock mitigating characteristics of seventeen, unconfined materials. The nominal input for these tests is an incident compressive wave with 50 fps peak (1,500 micro var-epsilon peak) amplitude and a 100 micros duration (measured at 10% amplitude)

  5. Tetrairon(III) Single Molecule Magnet Studied by Scanning Tunneling Microscopy and Spectroscopy

    Science.gov (United States)

    Oh, Youngtek; Jeong, Hogyun; Lee, Minjun; Kwon, Jeonghoon; Yu, Jaejun; Mamun, Shariful Islam; Gupta, Gajendra; Kim, Jinkwon; Kuk, Young

    2011-03-01

    Tetrairon(III) single-molecule magnet (SMM) on a clean Au(111) has studied using scanning tunneling microscopy (STM) and spectroscopy (STS) to understand quantum mechanical tunneling of magnetization and hysteresis of pure molecular origin. Before the STM studies, elemental analysis, proton nuclear magnetic resonance (NMR) measurement and Energy Dispersive X- ray Spectroscopy (EDS) were carried out to check the robustness of the sample. The STM image of this molecule shows a hexagonal shape, with a phenyl ring at the center and surrounding six dipivaloylmethane ligands. Two peaks are observed at 0.5 eV, 1.5 eV in the STS results, agreeing well with the first principles calculations. Spin-polarized scanning tunneling microscopy (SPSTM) measurements have been performed with a magnetic tip to get the magnetization image of the SMM. We could observe the antiferromagnetic coupling and a centered- triangular topology with six alkoxo bridges inside the molecule while applying external magnetic fields.

  6. Experimental study of wind tunnel performance by a two-component laserDopplerAnemometer

    Directory of Open Access Journals (Sweden)

    M Pourmahabadian

    2005-10-01

    Full Text Available Background and Aims: This survey studies the wind tunnel performance by a two- componentlaser Doppler Anemometer, so some experiments were carried out to assess the performance of awind tunnel.Method: The tunnel was capable to produce air velocity of up to 40 m/s.. Measurements ofvelocity profiles have been made actors the test section of wind tunnel through the using a twocomponentfiber optic Laser Doppler anemometer. Measurements of velocity profiles andturbulence intensities have been made across the test section of the wind tunnel using a twocomponentfiber optic Laser Doppler anemometer (I.D.A for wind speeds ranging from 1 to3m/s.Results: Performance rests of velocity profiles at a given flow rate and various position of aerosolgenerator showed that although uniformity of flow dependent to the place of an atomizer (asaerosol generator but the variation of wind speed across the test section meets the wind speedrequirements, as specified by US EPAfor 3m/s only.Conclusion:At time which particles velocity reach to less than one micron, the air velocity relateson the similarity of particles and

  7. A study of shock mitigating materials in a split Hopkinson bar configuration. Phase 2

    International Nuclear Information System (INIS)

    Bateman, V.I.; Brown, F.A.; Hansen, N.R.

    1997-01-01

    Sandia National Laboratories (SNL) designs mechanical systems with electronics that must survive high shock environments. These mechanical systems include penetrators that must survive soil and rock penetration, nuclear transportation casks that must survive transportation environments, and laydown weapons that must survive delivery impact. These mechanical systems contain electronics that may operate during and after the high shock environment and that must be protected from the high shock environments. A study has been started to improve the packaging techniques for the advanced electronics utilized in these mechanical systems because current packaging techniques are inadequate for these sensitive electronics. In many cases, it has been found that the packaging techniques currently used not only do not mitigate the shock environment but actually amplify the shock environment. An ambitious goal for this packaging study is to avoid amplification and possibly attenuate the shock environment before it reached the electronics contained in the various mechanical systems. Here, a study to compare two thickness values, 0.125 and 0.250 in. of five materials, GE RTV 630, HS II Silicone, Polysulfide Rubber, Sylgard 184, and Teflon for their shock mitigating characteristics with a split Hopkinson bar configuration has been completed. The five materials have been tested in both unconfined and confined conditions at ambient temperature and with two applied loads of 750 με peak (25 fps peak) with a 100 micros duration, measured at 10% amplitude, and 1500 με peak (50 fps peak) with a 100 micros duration, measured at 10% amplitude. The five materials have been tested at ambient, cold (-65 F), and hot (+165 F) for the unconfined condition with the 750 με peak (25 fps peak) applied load. Time domain and frequency domain analyses of the split Hopkinson bar data have been performed to compare how these materials lengthen the shock pulse, attenuate the shock pulse, reflect high

  8. Various continuum approaches for studying shock wave structure in carbon dioxide

    Science.gov (United States)

    Alekseev, I. V.; Kosareva, A. A.; Kustova, E. V.; Nagnibeda, E. A.

    2018-05-01

    Shock wave structure in carbon dioxide is studied using different continuum models within the framework of one-temperature thermal equilibrium flow description. Navier-Stokes and Euler equations as well as commonly used Rankine-Hugoniot equations with different specific heat ratios are used to find the gas-dynamic parameters behind the shock wave. The accuracy of the Rankine-Hugoniot relations in polyatomic gases is assessed, and it is shown that they give a considerable error in the predicted values of fluid-dynamic variables. The effect of bulk viscosity on the shock wave structure in CO2 is evaluated. Taking into account bulk viscosity yields a significant increase in the shock wave width; for the complete model, the shock wave thickness varies non-monotonically with the Mach number.

  9. Central venous pressure and shock index predict lack of hemodynamic response to volume expansion in septic shock: a prospective, observational study.

    Science.gov (United States)

    Lanspa, Michael J; Brown, Samuel M; Hirshberg, Eliotte L; Jones, Jason P; Grissom, Colin K

    2012-12-01

    Volume expansion is a common therapeutic intervention in septic shock, although patient response to the intervention is difficult to predict. Central venous pressure (CVP) and shock index have been used independently to guide volume expansion, although their use is questionable. We hypothesize that a combination of these measurements will be useful. In a prospective, observational study, patients with early septic shock received 10-mL/kg volume expansion at their treating physician's discretion after brief initial resuscitation in the emergency department. Central venous pressure and shock index were measured before volume expansion interventions. Cardiac index was measured immediately before and after the volume expansion using transthoracic echocardiography. Hemodynamic response was defined as an increase in a cardiac index of 15% or greater. Thirty-four volume expansions were observed in 25 patients. A CVP of 8 mm Hg or greater and a shock index of 1 beat min(-1) mm Hg(-1) or less individually had a good negative predictive value (83% and 88%, respectively). Of 34 volume expansions, the combination of both a high CVP and a low shock index was extremely unlikely to elicit hemodynamic response (negative predictive value, 93%; P = .02). Volume expansion in patients with early septic shock with a CVP of 8 mm Hg or greater and a shock index of 1 beat min(-1) mm Hg(-1) or less is unlikely to lead to an increase in cardiac index. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. Finite element study of a HDR-RPV-section including a nozzle under thermal shock transient

    Energy Technology Data Exchange (ETDEWEB)

    Roos, E [Stuttgart Univ. (Germany); Katzenmeier, G [Forschungszentrum Juelich GmbH (Germany); Wanner, R; Mercier, O [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1988-12-31

    This document presents a finite element study of a reactor pressure vessel section under thermal stresses. The strength properties of the vessel walls are studied as well as cracks due to the thermo-shock transient. (TEC). 6 refs.

  11. Study of the tunneling effect within lattices with cubic structure on varying temperature

    International Nuclear Information System (INIS)

    Frisone, F.

    2008-01-01

    In this theoretical study, it is underlined that the presence of micro-cracks in the lattice structure increases the probability of tunneling effect between two deuterons by some orders of magnitude with respect to non-deformed lattices. We have derived an expression to compute the tunneling probability within a micro-crack, and hypothesized a D + 2 -D + 2 binding mechanism. Finally, the overall indications provided by these theoretical simulations appear to suggest that the deformation of the crystalline lattice, at varying temperature, seems able to influence the process of tunneling between the deuterons in the metal, while the forced loading with D 2 has, in general, no evident positive effects in pure metals, but in some cases could, on the contrary, condition the phenomenon negatively. (authors)

  12. Overview of the Integrated Pressurized Thermal-Shock (IPTS) study

    International Nuclear Information System (INIS)

    Cheverton, R.D.

    1990-01-01

    By the early 1980s, (PTS)-related, deterministic, vessel-integrity studies sponsored by the US Nuclear Regulatory Commission (NRC) indicated a potential for failure of some PWR vessels before design end of life, in the event of a postulated severe PTS transient. In response, the NRC established screening criteria, in the form of limiting values of the reference nil-ductility transition temperature (RT NDT ), and initiated the development of a probabilistic methodology for evaluating vessel integrity. This latter effort, referred to as the Integrated Pressurized Thermal-Shock (IPTS) Program, included development of techniques for postulating PTS transients, estimating their frequencies, and calculating the probability of vessel failure for a specific transient. Summing the products of frequency of transient and conditional probability of failure for each of the many postulated transients provide a calculated value of the frequency of failure. The IPTS Program also included the application of the IPTS methodology to three US PWR plants (Oconee-1, Calvert Cliffs-1, and HBRobinson-2) and the specification of a maximum permissible value of the calculated frequency of vessel failure. Another important purpose of the IPTS study was to determine, through application of the IPTS methodology, which design and operating features, parameters, and PTS transients were dominant in affecting the calculated frequency of failure. The scope of the IPTS Program included the development of a probabilistic fracture-mechanics capability, modification of the TRAC and RELAP5 thermal/hydraulic codes, and development of the methodology for estimating the uncertainty in the calculated frequency of vessel failure

  13. Experimental study of the Richtmyer-Meshkov instability induced by a Mach 3 shock wave

    International Nuclear Information System (INIS)

    BP Puranik; JG Oakley; MH Anderson; R Bonaazza

    2003-01-01

    OAK-B135 An experimental investigation of a shock-induced interfacial instability (Richtmyer-Meshkov instability) is undertaken in an effort to study temporal evolution of interfacial perturbations in the late stages of development. The experiments are performed in a vertical shock tube with a square cross-section. A membraneless interface is prepared by retracting a sinusoidally shaped metal plate initially separating carbon dioxide from air, with both gases initially at atmospheric pressure. With carbon dioxide above the plate, the Rayleigh-Taylor instability commences as the plate is retracted and the amplitude of the initial sinusoidal perturbation imposed on the interface begins to grow. The interface is accelerated by a strong shock wave (M=3.08) while its shape is still sinusoidal and before the Kelvin-Helmhotz instability distorts it into the well known mushroom-like structures; its initial amplitude to wavelength ratio is large enough that the interface evolution enters its nonlinear stage very shortly after shock acceleration. The pre-shock evolution of the interface due to the Rayleigh-Taylor instability and the post-shock evolution of the interface due to the Richtmyer-Meshkov instability are visualized using planar Mie scattering. The pre-shock evolution of the interface is carried out in an independent set of experiments. The initial conditions for the Richtmyer-Meshkov experiment are determined from the pre-shock Rayleigh-Taylor growth. One image of the post-shock interface is obtained per experiment and image sequences, showing the post-shock evolution of the interface, are constructed from several experiments. The growth rate of the perturbation amplitude is measured and compared with two recent analytical models of the Richtmyer-Meshkov instability

  14. Prediction of Brittle Failure for TBM Tunnels in Anisotropic Rock: A Case Study from Northern Norway

    Science.gov (United States)

    Dammyr, Øyvind

    2016-06-01

    Prediction of spalling and rock burst is especially important for hard rock TBM tunneling, because failure can have larger impact than in a drill and blast tunnel and ultimately threaten excavation feasibility. The majority of research on brittle failure has focused on rock types with isotropic behavior. This paper gives a review of existing theory and its application before a 3.5-m-diameter TBM tunnel in foliated granitic gneiss is used as a case to study brittle failure characteristics of anisotropic rock. Important aspects that should be considered in order to predict brittle failure in anisotropic rock are highlighted. Foliation is responsible for considerable strength anisotropy and is believed to influence the preferred side of v-shaped notch development in the investigated tunnel. Prediction methods such as the semi- empirical criterion, the Hoek- Brown brittle parameters, and the non-linear damage initiation and spalling limit method give reliable results; but only as long as the angle between compression axis and foliation in uniaxial compressive tests is relevant, dependent on the relation between tunnel trend/plunge, strike/dip of foliation, and tunnel boundary stresses. It is further demonstrated that local in situ stress variations, for example, due to the presence of discontinuities, can have profound impact on failure predictions. Other carefully documented case studies into the brittle failure nature of rock, in particular anisotropic rock, are encouraged in order to expand the existing and relatively small database. This will be valuable for future TBM planning and construction stages in highly stressed brittle anisotropic rock.

  15. Tunneling spectroscopy study of YBa2Cu3O7 thin films using a cryogenic scanning tunneling microscope

    International Nuclear Information System (INIS)

    Wilkins, R.; Amman, M.; Soltis, R.E.; Ben-Jacob, E.; Jaklevic, R.C.

    1990-01-01

    We have measured reproducible tunneling spectra on YBa 2 Cu 3 O 7 (T c ∼85 K) thin films (thickness ∼2 μm) with a cryogenic scanning tunneling microscope. We find that the I-V curves are generally of three types. The most common type, featured in a large majority of the data, shows a region of high conductance at zero bias. The amplitude of this region is inversely proportional to the tunneling resistance between the tip and sample. It is possible that this can be explained in terms of Josephson effects within the films, although an alternative is given based on electronic self-energy corrections. Data showing capacitive charging steps are analyzed in terms of two ultrasmall tunnel junctions in series.. Theoretical fits to the data give specific values of the junction parameters that are consistent with the assumed geometry of the tip probing an individual grain of the film. The third type of I-V curves exhibits negative differential resistance. We conclude that this phenomenon is probably due to tunneling to localized states in the surface oxide. We also present and discuss data with energy-gap-like behavior; the best example gives Δ to be about 27 mV

  16. Computational Study of Shock/Plume Interactions Between Multiple Jets in Supersonic Crossflow

    Science.gov (United States)

    Tylczak, Erik B.

    The interaction of multiple jets in supersonic crossflow is simulated using hybrid Reynolds- Averaged Navier Stokes and Large Eddy Simulation turbulence models. The blockage of a jet generates a curved bow shock, and in multi-jet flows, each shock impinges on the other fuel plumes. The curved nature of each shock generates vorticity directly, and the impingement of each shock on the vortical structures within the adjacent fuel plumes strengthens vortical structures already present. These stirring motions are the major driver of fuel-air mixing, and so mixing enhancement is predicted to occur in multi-port configurations. The primary geometry considered is that of the combustion duct at the Calspan- University of Buffalo Research Center 48" Large Energy National Shock (LENS) tunnel. This geometry was developed to be representative of the geometry and flow physics of the Flight 2 test vehicle of the Hypersonic International Flight Research Experimenta- tion Program (HiFIRE-2). This geometry takes the form of a symmetric pair of external compression ramps that feed an isolator of approximately 4" x 1" cross-section. Nine interdigitated flush-wall injectors, four on one wall and five on the other, inject hydrogen at an angle of 30 degrees to the freestream. Two freestream flow conditions are consid- ered: approximately Mach 7.2 at a static temperature of 214K and a density of 0.039 kg/m3 for the five-injector case, and approximately Mach 8.9 at a static temperature of 167K and density of 0.014 kg/m 3 for the nine-injector case. Validation computations are performed on a single-port experiment with an imposed shock wave. Unsteady calculations are performed on five-port and nine-port configura- tions, and the five-port configuration is compared to calculations performed with only a single active port on the same geometry. Analysis of statistical data demonstrates enhanced mixing in the multi-port configurations in regions where shock impingement occurs.

  17. An experimental study of the exergetic performance of an underground air tunnel system for greenhouse cooling

    International Nuclear Information System (INIS)

    Ozgener, Leyla; Ozgener, Onder

    2010-01-01

    The present study highlights the exergetic performance characteristics of an underground air tunnel for greenhouse cooling with a 47 m horizontal, 56 cm nominal diameter U-bend buried galvanized ground heat exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir, Turkey. Underground air tunnel systems, also known as earth-to-air heat exchangers, are recognized to be outstanding heating, cooling and air heating systems. On the other hand, they have not been used yet in the Turkish market. Greenhouses also have important economical potential in Turkey's agricultural sector. Greenhouses should be cooled during the summer or hot days. In order to establish optimum growth conditions in greenhouses, renewable energy sources should be utilized as much as possible. It is expected that effective use of underground air tunnels with a suitable technology in the modern greenhouses will play a leading role in Turkey in the foreseeable future. The exergy transports between the components and the destructions in each of the components of the system are determined for the average measured parameters obtained from the experimental results. Exergetic efficiencies of the system components are determined in an attempt to assess their individual performances and the potential for improvements is also presented. The daily maximum cooling coefficient of performances (COP) values for the system are also obtained to be 15.8. The total average COP in the experimental period is found to be 10.09. The system COP was calculated based on the amount of cooling produced by the air tunnel and the amount of power required to move the air through the tunnel, while the exergetic efficiency of the air tunnel is found to be in a range among 57.8-63.2%. The overall exergy efficiency value for the system on a product/fuel basis is found to be 60.7%. (author)

  18. A numerical study of Richtmyer endash Meshkov instability driven by cylindrical shocks

    International Nuclear Information System (INIS)

    Zhang, Q.; Graham, M.J.

    1998-01-01

    As an incident shock wave hits a material interface between two fluids of different densities, the interface becomes unstable. Small disturbances at the interface start to grow. This interfacial instability is known as a Richtmyer endash Meshkov (RM) instability. It plays an important role in the studies of inertial confinement fusion and supernova. The majority of studies of the RM instability were in plane geometry emdash namely, plane shocks in Cartesian coordinates. We present a systematic numerical study of the RM instability driven by cylindrical shocks for both the imploding and exploding cases. The imploding (exploding) case refers to a cylindrical shock colliding with the material interface from the outside in (inside out). The phenomenon of reshock caused by the waves reflected from the origin is also studied. A qualitative understanding of this system has been achieved. Detailed studies of the growth rate of the fingers at the unstable interface are presented. copyright 1998 American Institute of Physics

  19. Numerical Study of Erosion, Heating, and Acceleration of the Magnetic Cloud as Impacted by Fast Shock

    International Nuclear Information System (INIS)

    Mao, Shoudi; He, Jiansen; Yang, Liping; Wang, Linghua; Zhang, Lei

    2017-01-01

    The impact of an overtaking fast shock on a magnetic cloud (MC) is a pivotal process in CME–CME (CME: coronal mass ejection) interactions and CME–SIR (SIR: stream interaction region) interactions. MC with a strong and rotating magnetic field is usually deemed a crucial part of CMEs. To study the impact of a fast shock on an MC, we perform a 2.5 dimensional numerical magnetohydrodynamic simulation. Two cases are run in this study: without and with impact by fast shock. In the former case, the MC expands gradually from its initial state and drives a relatively slow magnetic reconnection with the ambient magnetic field. Analyses of forces near the core of the MC as a whole body indicates that the solar gravity is quite small compared to the Lorentz force and the pressure gradient force. In the second run, a fast shock propagates, relative to the background plasma, at a speed twice that of the perpendicular fast magnetosonic speed, catches up with and takes over the MC. Due to the penetration of the fast shock, the MC is highly compressed and heated, with the temperature growth rate enhanced by a factor of about 10 and the velocity increased to about half of the shock speed. The magnetic reconnection with ambient magnetic field is also sped up by a factor of two to four in reconnection rate as a result of the enhanced density of the current sheet, which is squeezed by the forward motion of the shocked MC.

  20. Numerical Study of Erosion, Heating, and Acceleration of the Magnetic Cloud as Impacted by Fast Shock

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Shoudi; He, Jiansen; Yang, Liping; Wang, Linghua [School of Earth and Space Sciences, Peking University No. 5 Yiheyuan Road, Haidian District Beijing, 100871 (China); Zhang, Lei, E-mail: jshept@gmail.com [SIGMA Weather Group, State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences No.1 Nanertiao, Zhongguancun, Haidian district Beijing, 100190 (China)

    2017-06-20

    The impact of an overtaking fast shock on a magnetic cloud (MC) is a pivotal process in CME–CME (CME: coronal mass ejection) interactions and CME–SIR (SIR: stream interaction region) interactions. MC with a strong and rotating magnetic field is usually deemed a crucial part of CMEs. To study the impact of a fast shock on an MC, we perform a 2.5 dimensional numerical magnetohydrodynamic simulation. Two cases are run in this study: without and with impact by fast shock. In the former case, the MC expands gradually from its initial state and drives a relatively slow magnetic reconnection with the ambient magnetic field. Analyses of forces near the core of the MC as a whole body indicates that the solar gravity is quite small compared to the Lorentz force and the pressure gradient force. In the second run, a fast shock propagates, relative to the background plasma, at a speed twice that of the perpendicular fast magnetosonic speed, catches up with and takes over the MC. Due to the penetration of the fast shock, the MC is highly compressed and heated, with the temperature growth rate enhanced by a factor of about 10 and the velocity increased to about half of the shock speed. The magnetic reconnection with ambient magnetic field is also sped up by a factor of two to four in reconnection rate as a result of the enhanced density of the current sheet, which is squeezed by the forward motion of the shocked MC.

  1. Adsorption of Cu phthalocyanine on Pt modified Ge(001): A scanning tunneling microscopy study

    NARCIS (Netherlands)

    Saedi, A.; Berkelaar, Robin P.; Kumar, Avijit; Poelsema, Bene; Zandvliet, Henricus J.W.

    2010-01-01

    The adsorption configurations of copper phthalocyanine (CuPc) molecules on platinum-modified Ge(001) have been studied using scanning tunneling microscopy. After deposition at room temperature and cooling down to 77 K the CuPc molecules are still dynamic. However, after annealing at 550±50 K, the

  2. Carpal tunnel sonography by the rheumatologist versus nerve conduction study by the neurologist

    NARCIS (Netherlands)

    Swen, WAA; Jacobs, JWG; Bussemaker, FEAM; de Waard, J; Bijlsma, JWJ

    Objective. To determine the value of sonogaphy (SG) performed by the rheumatologist to diagnose carpal tunnel syndrome (CTS). Methods. Sixty-three patients with clinical signs of CTS according to the neurologist. based on patient history and clinical examination, were studied. In the 6 weeks prior

  3. Tunneling Spectroscopy Study of Spin-Polarized Quasiparticle Injection Effects in Cuparate/Manganite Heterostructures

    Science.gov (United States)

    Wei, J. Y. T.; Yeh, N. C.; Vasquez, R. P.

    1998-01-01

    Scanning tunneling spectroscopy was performed at 4.2K on epitaxial thin-film heterostructures comprising YBa2Cu3O7 and La0.7Ca0.3MnO3, to study the microscopic effects of spin-polarized quasiparticle injection from the half-metallic ferromagnetic manganite on the high-Tc cuprate superconductor.

  4. Fermilab digs 4,000-foot tunnel for neutrino study near Batavia

    CERN Multimedia

    Grady, W

    2002-01-01

    As part of a construction project that began more than two years ago, workers have carved out 4,000 feet of tunnel and two huge caverns under a portion of Fermilab's site near Batavia. The $171 million project will provide research facilities for an experiment designed to study neutrinos (1 page).

  5. Prevalence, course and determinants of carpal tunnel syndrome symptoms during pregnancy : A prospective study

    NARCIS (Netherlands)

    Meems, M.; Truijens, S. E. M.; Spek, V.; Visser, L. H.; Pop, V. J. M.

    2015-01-01

    Objective To investigate the prevalence, severity and relation to fluid retention of self-reported pregnancy-related carpal tunnel syndrome (CTS) symptoms in a large sample of pregnant women. Design A prospective longitudinal cohort study. Setting Dutch women who became pregnant between January 2013

  6. Political Shocks and Abnormal Returns During the Taiwan Crisis: An Event Study Analysis

    National Research Council Canada - National Science Library

    Steeves, Geoffrey

    2002-01-01

    .... Focusing on the 1996 Taiwan Crisis, by means of event study analysis, this paper attempts to determine the extent to which this political shock affected the Taiwanese, and surrounding Japanese stock markets...

  7. Laser driven shock wave experiments for equation of state studies at megabar pressures

    CERN Document Server

    Pant, H C; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K

    2002-01-01

    We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 mu m wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments.

  8. Numerical study of the Kadomtsev-Petviashvili equation and dispersive shock waves

    Science.gov (United States)

    Grava, T.; Klein, C.; Pitton, G.

    2018-02-01

    A detailed numerical study of the long time behaviour of dispersive shock waves in solutions to the Kadomtsev-Petviashvili (KP) I equation is presented. It is shown that modulated lump solutions emerge from the dispersive shock waves. For the description of dispersive shock waves, Whitham modulation equations for KP are obtained. It is shown that the modulation equations near the soliton line are hyperbolic for the KPII equation while they are elliptic for the KPI equation leading to a focusing effect and the formation of lumps. Such a behaviour is similar to the appearance of breathers for the focusing nonlinear Schrödinger equation in the semiclassical limit.

  9. Shock Tube/Laser Absorption Studies of Jet Fuels at Low Temperatures (600-1200K)

    Science.gov (United States)

    2013-08-27

    Davidson, Ronald K. Hanson. A second-generation aerosol shock tube and its use in studying ignition delay times of large biodiesel surrogates, 28th... Biodiesel Surrogate behind Reflected Shock Waves,” 8th US National Combustion Meeting, Paper 070RK-0008 Park City, UT 5/2013.   These  studies provide...www.elsevier .com/locate / fuel 1. Introduction Normal alkanes have been widely used as fuels and are major components of many commercial transportation fuels

  10. Scaled experiments using the helium technique to study the vehicular blockage effect on longitudinal ventilation control in tunnels

    DEFF Research Database (Denmark)

    Alva, Wilson Ulises Rojas; Jomaas, Grunde; Dederichs, Anne

    2015-01-01

    A model tunnel (1:30 compared to a standard tunnel section) with a helium-air smoke mixture was used to study the vehicular blockage effect on longitudinal ventilation smoke control. The experimental results showed excellent agreement with full-scale data and confirmed that the critical velocity...

  11. Laboratory studies of stagnating plasma flows with applications to inner solar system and stellar bow shocks

    Science.gov (United States)

    Weber, T. E.; Smith, R. J.; Hsu, S. C.

    2016-10-01

    Supercritical magnetized collisionless shocks are thought to play a dominant role in the overall partition of energy throughout the universe by converting flow kinetic energy to other forms such as thermal and supra-thermal populations, magnetic field enhancement, turbulence, and energetic particles. The Magnetized Shock Experiment (MSX) at LANL creates conditions similar to those of inner solar system and stellar bow shocks by accelerating hot (100s of eV during translation) dense (1022 - 1023 m-3) Field Reversed Configuration (FRC) plasmoids to 100s of km/s; resulting in β 1, collisionless plasma flows with Msonic and MAlfvén 10. The drifting FRC can be made to impinge upon a variety of static obstacles including: a strong mirror or cusp magnetic field (mimicking magnetically excited shocks such as the Earth's bow shock), plasma pileup from a solid obstacle (similar to the bow shocks of Mercury and the Moon), and a neural gas puff (bow shocks of Venus or the comets). Characteristic shock length and time scales that are both large enough to observe yet small enough to fit within the experiment, enabling study of the complex interplay of kinetic and fluid processes that mediate cosmic shocks and can generate non-thermal distributions, produce density and magnetic field enhancements much greater than predicted by fluid theory, and accelerate particles. An overview of the experimental program will be presented, including recent results. This work is supported by the U.S. DOE, Office of Science, Office of Fusion Energy Sciences under Contract No. DE-AC52-06NA25369.

  12. Study on Oxygen Supply Standard for Physical Health of Construction Personnel of High-Altitude Tunnels

    Directory of Open Access Journals (Sweden)

    Chun Guo

    2015-12-01

    Full Text Available The low atmospheric pressure and low oxygen content in high-altitude environment have great impacts on the functions of human body. Especially for the personnel engaged in complicated physical labor such as tunnel construction, high altitude can cause a series of adverse physiological reactions, which may result in multiple high-altitude diseases and even death in severe cases. Artificial oxygen supply is required to ensure health and safety of construction personnel in hypoxic environments. However, there are no provisions for oxygen supply standard for tunnel construction personnel in high-altitude areas in current tunnel construction specifications. As a result, this paper has theoretically studied the impacts of high-altitude environment on human bodies, analyzed the relationship between labor intensity and oxygen consumption in high-altitude areas and determined the critical oxygen-supply altitude values for tunnel construction based on two different standard evaluation systems, i.e., variation of air density and equivalent PIO2. In addition, it has finally determined the oxygen supply standard for construction personnel in high-altitude areas based on the relationship between construction labor intensity and oxygen consumption.

  13. Analysis of factors affecting failure of glass cermet tunnel restorations in a multi-center study.

    Science.gov (United States)

    Pilebro, C E; van Dijken, J W

    2001-06-01

    The aim of this study was to analyze factors influencing the failures of tunnel restorations performed with a glass cermet cement (Ketac Silver). Caries activity, lesion size, tunnel cavity opening size, partial or total tunnel, composite lamination or operating time showed no significant correlation to failure rate. Twelve dentists in eight clinics clinically experienced and familiar with the tunnel technique placed 374 restorations. The occlusal sections of fifty percent of the restorations were laminated with hybrid resin composite. The results of the yearly clinical and radiographic evaluations over the course of 3 years were correlated to factors that could influence the failure rate using logistic regression analysis. At the 3-year recall a cumulative number of 305 restorations were available. The cumulative replacement rate was 20%. The main reasons for replacement were marginal ridge fracture (14%) and dentin caries (3%). Another 7% of the restorations which had not been replaced were classified as failures because of untreated dentin caries. The only significant variable observed was the individual failure rate of the participating dentists varying between 9 and 50% (p=0.013).

  14. Case Study on Economic Return on Investments for Safety and Emergency Lighting in Road Tunnels

    Directory of Open Access Journals (Sweden)

    Ferdinando Salata

    2015-07-01

    Full Text Available While planning a double-hole road tunnel with a length higher than one km, it is important to pay attention to the safety factor if an accident occurs. If there is a power outage, in order to avoid critical situations that could jeopardize the safety of the people present (facilitating the stream coming out from the tunnel and the arrival of the emergency personnel, it is really important to guarantee uninterrupted lighting of roadways, mandatory emergency lay-bys, and ways of escape. Uninterrupted service of the lighting systems supply must be guaranteed, in accordance with the current regulations, through the exertion of UPS (Uninterruptible Power Supply and power units. During tunnel construction, such devices represent a cost that must be amortized. In this case study, which takes into consideration a section of a road tunnel characterized by emergency lay-bys and ways of escape, emergency and security lighting were planned and installation and management costs were evaluated. The goal of this research was the creation of a cash flow thanks to the energy generated by photovoltaic panels, in a way that the service life of the system (25 years coincided with the amortization of the costs of the backup electrical equipment installation (complying with the regulations. The possibility of over-dimensioning the UPS and providing it with a proper photovoltaic panel surface (235 kWp to generate and exchange electric energy with the grid was taken into consideration.

  15. Fragment molecular orbital study on electron tunneling mechanisms in bacterial photosynthetic reaction center.

    Science.gov (United States)

    Kitoh-Nishioka, Hirotaka; Ando, Koji

    2012-11-01

    The tunneling mechanisms of electron transfers (ETs) in photosynthetic reaction center of Blastochloris viridis are studied by the ab initio fragment molecular orbital (FMO) method combined with the generalized Mulliken-Hush (GMH) and the bridge Green function (GF) calculations of the electronic coupling T(DA) and the tunneling current method for the ET pathway analysis at the fragment-based resolution. For the ET from batctriopheophytin (H(L)) to menaquinone (MQ), a major tunneling current through Trp M250 and a minor back flow via Ala M215, Ala M216, and His M217 are quantified. For the ET from MQ to ubiquinone, the major tunneling pathway via the nonheme Fe(2+) and His L190 is identified as well as minor pathway via His M217 and small back flows involving His L230, Glu M232, and His M264. At the given molecular structure from X-ray experiment, the spin state of the Fe(2+) ion, its replacement by Zn(2+), or its removal are found to affect the T(DA) value by factors within 2.2. The calculated T(DA) values, together with experimentally estimated values of the driving force and the reorganization energy, give the ET rates in reasonable agreement with experiments.

  16. Numerical Study on Different Series Modes of Jet Fan in a Longitudinal Tunnel Ventilation System

    Directory of Open Access Journals (Sweden)

    Guihong Pei

    2014-01-01

    Full Text Available Efficient ventilation systems will contribute to maintaining air quality in the tunnel. In order to improve ventilation performance in normal traffic condition, the 3D tunnel models were established according to the original design for the tunnel located in central plains of China. Based on the commercial CFD software Fluent 6.3 and k-ε turbulence model, numerical simulations were carried out to study the patterns of jet flow and the optimization of fan combinations. It is found that the axial velocity profile obtained from numerical simulation agrees quite well with turbulent free jet theory although there is a little difference on the magnitude. The comparison of four combination modes under the condition of operating four fans indicates that the ventilation effectiveness is affected mainly by both the interval of adjacent groups of fans and the combination modes of operational fans. According to the simulation results, a novel combination mode which consists of a group double paralleled fans and two groups single fan is designed. The novel combination mode is regarded as the optimum combination mode with respect to maximizing air velocity in the tunnel. Compared to the traditional combination modes, it will increase the air velocity by 5.7%.

  17. Ab initio simulation study of defect assisted Zener tunneling in GaAs diode

    Science.gov (United States)

    Lu, Juan; Fan, Zhi-Qiang; Gong, Jian; Jiang, Xiang-Wei

    2017-06-01

    The band to band tunneling of defective GaAs nano-junction is studied by using the non-equilibrium Green's function formalism with density functional theory. Aiming at performance improvement, two types of defect-induced transport behaviors are reported in this work. By examining the partial density of states of the system, we find the substitutional defect OAs that locates in the middle of tunneling region will introduce band-gap states, which can be used as stepping stones to increase the tunneling current nearly 3 times higher at large bias voltage (Vb≥0.3V). Another type of defects SeAs and VGa (Ga vacancy) create donor and acceptor states at the edge of conduction band (CB) and valence band (VB)respectively, which can change the band bending of the junction as well as increase the tunneling field obtaining a 1.5 times higher ON current. This provides an effective defect engineering approach for next generation TFET device design.

  18. Experimental methods of shock wave research

    CERN Document Server

    Seiler, Friedrich

    2016-01-01

    This comprehensive and carefully edited volume presents a variety of experimental methods used in Shock Waves research. In 14 self contained chapters this 9th volume of the “Shock Wave Science and Technology Reference Library” presents the experimental methods used in Shock Tubes, Shock Tunnels and Expansion Tubes facilities. Also described is their set-up and operation. The uses of an arc heated wind tunnel and a gun tunnel are also contained in this volume. Whenever possible, in addition to the technical description some typical scientific results obtained using such facilities are described. Additionally, this authoritative book includes techniques for measuring physical properties of blast waves and laser generated shock waves. Information about active shock wave laboratories at different locations around the world that are not described in the chapters herein is given in the Appendix, making this book useful for every researcher involved in shock/blast wave phenomena.

  19. DSMC Computations for Regions of Shock/Shock and Shock/Boundary Layer Interaction

    Science.gov (United States)

    Moss, James N.

    2001-01-01

    This paper presents the results of a numerical study of hypersonic interacting flows at flow conditions that include those for which experiments have been conducted in the Calspan-University of Buffalo Research Center (CUBRC) Large Energy National Shock (LENS) tunnel and the ONERA R5Ch low-density wind tunnel. The computations are made with the direct simulation Monte Carlo (DSMC) method of Bird. The focus is on Mach 9.3 to 11.4 flows about flared axisymmetric configurations, both hollow cylinder flares and double cones. The results presented highlight the sensitivity of the calculations to grid resolution, provide results concerning the conditions for incipient separation, and provide information concerning the flow structure and surface results for the extent of separation, heating, pressure, and skin friction.

  20. Proton tunneling in solids

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, J.

    1998-10-01

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

  1. Proton tunneling in solids

    International Nuclear Information System (INIS)

    Kondo, J.

    1998-01-01

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

  2. Theoretical study of the porosity effects on the shock response of graphitic materials

    Directory of Open Access Journals (Sweden)

    Pineau Nicolas

    2015-01-01

    Full Text Available In this paper we present a theoretical study of the shock compression of porous graphite by means of combined Monte Carlo and molecular dynamics simulations using the LCBOPII potential. The results show that the Hugoniostat methods can be used with “pole” properties calculated from porous models to reproduce the experimental Hugoniot of pure graphite and diamond with good accuracy. The computed shock temperatures show a sharp increase for weak shocks which we analyze as the heating associated with the closure of the initial porosity. After this initial phase, the temperature increases with shock intensity at a rate comparable to monocrystalline graphite and diamond. These simulations data can be exploited in view to build a full equation of state for use in hydrodynamic simulations.

  3. A soap film shock tube to study two-dimensional compressible flows

    Energy Technology Data Exchange (ETDEWEB)

    Wen, C.Y.; Chen, Y.M.; Chang-Jian, S.K. [Dept. of Mechanical Engineering, Da-Yeh University Chang-Hwa (Taiwan)

    2001-07-01

    A new experimental approach to the study of the two-dimensional compressible flow phenomena is presented. In this technique, a variety of compressible flows were generated by bursting plane vertical soap films. An aureole and a ''shock wave'' preceding the rim of the expanding hole were clearly observed using traditional high-speed flash photography and a fast line-scan charge coupled device (CCD) camera. The moving shock wave images obtained from the line-scan CCD camera were similar to the x-t diagrams in gas dynamics. The moving shock waves cause thickness jumps and induce supersonic flows. Photographs of the supersonic flows over a cylinder and a wedge are presented. The results suggest clearly the feasibility of the ''soap film shock tube''. (orig.)

  4. A compact atomic force-scanning tunneling microscope for studying microelectronics and environmental aerosols

    International Nuclear Information System (INIS)

    Chen, G.

    1996-06-01

    by imaging ion-etched silicon surfaces and oxidized silicon surfaces. Tip artifacts and the vertical hysteresis of STM images of surfaces with deep grooves have been investigated and proved to be dependent not only on the shape of the tips but also on the noise of the detection system and the characteristics of the feedback circuit. Moreover, aerosol particles have been studied with this instrument. To our best knowledge, this is the first application of tunneling controlled AFM on environmental aerosol samples. (author)

  5. Electron Tunneling in Lithium Ammonia Solutions Probed by Frequency-Dependent Electron-Spin Relaxation Studies

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T.J.; Harmer, Jeffrey; Freed, Jack H.; Edwards, Peter P.

    2012-01-01

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T1) and spin-spin (T2) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multi-exponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1–10)×10−12 s over a temperature range 230–290K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a timescale of ca. 10−13 s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great potential

  6. Electron tunneling in lithium-ammonia solutions probed by frequency-dependent electron spin relaxation studies.

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T J; Harmer, Jeffrey; Freed, Jack H; Edwards, Peter P

    2012-06-06

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T(1)) and spin-spin (T(2)) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multiexponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1-10) × 10(-12) s over a temperature range 230-290 K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a time scale of ∼10(-13) s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great

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

    Directory of Open Access Journals (Sweden)

    Prasnna Jain

    2014-02-01

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

  8. Experimental study of radiative shocks at PALS facility

    Czech Academy of Sciences Publication Activity Database

    Stehlé, C.; Gonzalez, M.; Kozlová, Michaela; Rus, Bedřich; Mocek, Tomáš; Acef, O.; Colombier, J.P.; Lanz, T.; Champion, N.; Jakubczak, Krzysztof; Polan, Jiří; Barroso, P.; Baudin, D.; Audit, E.; Dostál, Jan; Stupka, Michal

    2010-01-01

    Roč. 28, č. 2 (2010), s. 253-261 ISSN 0263-0346 R&D Projects: GA MŠk(CZ) LC528 Institutional research plan: CEZ:AV0Z10100523 Keywords : laboratory astrophysics * hydrodynamics * laser plasmas * shocks * stellar formation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.656, year: 2010 http://journals.cambridge.org/action/displayFulltext?type=6&fid=7807203&jid=LPB&volumeId=28&issueId=02&aid=7807202&fulltextType=RA&fileId=S02630346100

  9. Local X-ray magnetic circular dichroism study of Fe/Cu(111) using a tunneling smart tip

    Energy Technology Data Exchange (ETDEWEB)

    DiLullo, Andrew; Shirato, Nozomi; Cummings, Marvin [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Kersell, Heath; Chang, Hao [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Ohio University, Athens, OH 45701 (United States); Rosenmann, Daniel; Miller, Dean; Freeland, John W. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Hla, Saw-Wai [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Ohio University, Athens, OH 45701 (United States); Rose, Volker, E-mail: vrose@anl.gov [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2016-01-28

    A tunneling smart tip of a synchrotron X-ray scanning tunneling microscope provides simultaneously localized topographic, elemental and magnetic information. Localized spectroscopy with simultaneous topographic, elemental and magnetic information is presented. A synchrotron X-ray scanning tunneling microscope has been employed for the local study of the X-ray magnetic circular dichroism at the Fe L{sub 2,3}-edges of a thin iron film grown on Cu(111). Polarization-dependent X-ray absorption spectra have been obtained through a tunneling smart tip that serves as a photoelectron detector. In contrast to conventional spin-polarized scanning tunneling microscopy, X-ray excitations provide magnetic contrast even with a non-magnetic tip. Intensity variations in the photoexcited tip current point to chemical variations within a single magnetic Fe domain.

  10. Analytic study of 1D diffusive relativistic shock acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Keshet, Uri, E-mail: ukeshet@bgu.ac.il [Physics Department, Ben-Gurion University of the Negev, POB 653, Be' er-Sheva 84105 (Israel)

    2017-10-01

    Diffusive shock acceleration (DSA) by relativistic shocks is thought to generate the dN / dE ∝ E{sup −p} spectra of charged particles in various astronomical relativistic flows. We show that for test particles in one dimension (1D), p {sup −1}=1−ln[γ{sub d}(1+β{sub d})]/ln[γ{sub u}(1+β{sub u})], where β{sub u}(β{sub d}) is the upstream (downstream) normalized velocity, and γ is the respective Lorentz factor. This analytically captures the main properties of relativistic DSA in higher dimensions, with no assumptions on the diffusion mechanism. Unlike 2D and 3D, here the spectrum is sensitive to the equation of state even in the ultra-relativistic limit, and (for a J(üttner-Synge equation of state) noticeably hardens with increasing 1<γ{sub u}<57, before logarithmically converging back to p (γ{sub u→∞})=2. The 1D spectrum is sensitive to drifts, but only in the downstream, and not in the ultra-relativistic limit.

  11. Study of laser-driven shock wave propagation in Plexiglas targets

    International Nuclear Information System (INIS)

    Dhareshwar, L.J.; Naik, P.A.; Pant, H.C.; Kaushik, T.C.

    1992-01-01

    An experimental study of laser-driven shock wave propagation in a transparent material such as Plexiglas using a high-speed optical shadowgraphy technique is presented in this paper. A Nd: glass laser was used to produce laser intensity in the range 10 12 -10 14 W/cm 2 on the target. Optical shadowgrams of the propagating shock front were recorded with a second-harmonic (0.53-μm) optical probe beam. Shock pressures were measured at various laser intensities, and the scaling was found to agree with the theoretically predicted value. Shock pressure values have also been obtained from a one-dimensional Lagrangian hydrodynamic simulation, and they match well with experimental results. Shadowgrams of shock fronts produced by nonuniform spatial laser beam irradiation profiles have shown complete smoothing when targets with a thin coating of a material of high atomic number such as gold were used. Shock pressures in such coated targets are also found to be considerably higher compared with those in uncoated targets. (Author)

  12. The diagnostic efficacy of clinical findings and electrophysiological studies in carpal tunnel syndrome

    OpenAIRE

    Buyukkoyuncu Pekel, Nilufer; Nar Senol, Pelin; Yildiz, Demet; Kilic, Ahmet Kasim; Kamaci Sener, Deniz; Seferoglu, Meral; Gunes, Aygul

    2017-01-01

    Objective. The aim of the study was to examine the relation between clinical findings, neurological examination and electrophysiological studies in diagnosing carpal tunnel syndrome (CTS) and share our institutional experience in patients with CTS. Methods. Patients presenting with complaints of pain, paresthesia, and weakness in hands who diagnosed CTS between 2014 and 2015 were examined retrospectively. Demographic characteristics, clinical and neurological examination findings and electrod...

  13. The tunnel project. Drill hole logging and structural geologic studies in the Grualia, the Lunner county

    International Nuclear Information System (INIS)

    Elvebakk, Harald; Braathen, Alvar; Roenning, Jan S.; Nordgulen, Oeystein

    2001-01-01

    In connection with the project ''Environmental and community useful tunnels'' the Norwegian Geologic Survey (NGU) has made geologic and geophysical investigations along parts of the tunnel at the Grualia in the Lunner county. The purpose of the geologic studies was to map and investigate weakness zones in the rock foundations. The geophysical studies aimed at testing techniques that was in little use in preliminary studies for tunnel operations. The methods used have been optical inspection of drill holes, measurements of temperature and conductivity in the water and the measuring of the natural gamma radiation in the drill holes. The resistivity in the drill holes is also determined and test pumping with flow measurements is carried out in order to calculate the well water influx capacity. These methods may contribute to information about the rock condition (cracking, water influx). Previously the NGU has made 2D resistivity measurements at the ground in the tunnel in order to map the weakness zones. The results from the measurements in 6 wells show large variations in the rock qualities. The wells are drilled towards indicated weakness zones. Open water conducting cracks and sections with largely cracked rocks are detected in or in the proximity of the tunnel route. The weakness zone between the hornfels and the syenite west of the Langvatnet is largely cracked, has a large water conducting capacity and there are some unstable masses. Further east several open, water- conducting cracks are detected in the syenite. Furthest to the east in the route cracked and unstable rocks are found. Several of the holes are blocked by ravines which confirm the poor rock quality. In the particular areas problems are to be expected during the operation with respect to water influx and stability. Methodically the drill hole studies have shown great value for the follow up of the 2D resistivity measurements on the ground. The indicated weakness zones through the 2D have been

  14. A theoretical and shock tube kinetic study on hydrogen abstraction from phenyl formate.

    Science.gov (United States)

    Ning, Hongbo; Liu, Dapeng; Wu, Junjun; Ma, Liuhao; Ren, Wei; Farooq, Aamir

    2018-06-12

    The hydrogen abstraction reactions of phenyl formate (PF) by different radicals (H/O(3P)/OH/HO2) were theoretically investigated. We calculated the reaction energetics for PF + H/O/OH using the composite method ROCBS-QB3//M06-2X/cc-pVTZ and that for PF + HO2 at the M06-2X/cc-pVTZ level of theory. The high-pressure limit rate constants were calculated using the transition state theory in conjunction with the 1-D hindered rotor approximation and tunneling correction. Three-parameter Arrhenius expressions of rate constants were provided over the temperature range of 500-2000 K. To validate the theoretical calculations, the overall rate constants of PF + OH → Products were measured in shock tube experiments at 968-1128 K and 1.16-1.25 atm using OH laser absorption. The predicted overall rate constants agree well with the shock tube data (within 15%) over the entire experimental conditions. Rate constant analysis indicates that the H-abstraction at the formic acid site dominates the PF consumption, whereas the contribution of H-abstractions at the aromatic ring increases with temperature. Additionally, comparisons of site-specific H-abstractions from PF with methyl formate, ethyl formate, benzene, and toluene were performed to understand the effects of the aromatic ring and side-chain substituent on H-abstraction rate constants.

  15. Ab Initio Studies of Shock-Induced Chemical Reactions of Inter-Metallics

    Science.gov (United States)

    Zaharieva, Roussislava; Hanagud, Sathya

    2009-06-01

    Shock-induced and shock assisted chemical reactions of intermetallic mixtures are studied by many researchers, using both experimental and theoretical techniques. The theoretical studies are primarily at continuum scales. The model frameworks include mixture theories and meso-scale models of grains of porous mixtures. The reaction models vary from equilibrium thermodynamic model to several non-equilibrium thermodynamic models. The shock-effects are primarily studied using appropriate conservation equations and numerical techniques to integrate the equations. All these models require material constants from experiments and estimates of transition states. Thus, the objective of this paper is to present studies based on ab initio techniques. The ab inito studies, to date, use ab inito molecular dynamics. This paper presents a study that uses shock pressures, and associated temperatures as starting variables. Then intermetallic mixtures are modeled as slabs. The required shock stresses are created by straining the lattice. Then, ab initio binding energy calculations are used to examine the stability of the reactions. Binding energies are obtained for different strain components super imposed on uniform compression and finite temperatures. Then, vibrational frequencies and nudge elastic band techniques are used to study reactivity and transition states. Examples include Ni and Al.

  16. Ballistic current transport studies of ferromagnetic multilayer films and tunnel junctions (invited)

    International Nuclear Information System (INIS)

    Rippard, W. H.; Perrella, A. C.; Buhrman, R. A.

    2001-01-01

    Three applications of ballistic electron microscopy are used to study, with nanometer-scale resolution, the magnetic and electronic properties of magnetic multilayer thin films and tunnel junctions. First, the capabilities of ballistic electron magnetic microscopy are demonstrated through an investigation of the switching behavior of continuous Ni 80 Fe 20 /Cu/Co trilayer films in the presence of an applied magnetic field. Next, the ballistic, hot-electron transport properties of Co films and multilayers formed by thermal evaporation and magnetron sputtering are compared, a comparison which reveals significant differences in the ballistic transmissivity of thin film multilayers formed by the two techniques. Finally, the electronic properties of thin aluminum oxide tunnel junctions formed by thermal evaporation and sputter deposition are investigated. Here the ballistic electron microscopy studies yield a direct measurement of the barrier height of the aluminum oxide barriers, a result that is invariant over a wide range of oxidation conditions. [copyright] 2001 American Institute of Physics

  17. A numerical study on the influence of slope and curvature on smoke flow in special section tunnel with natural ventilation

    Science.gov (United States)

    Wang, Wenzhou; Zhou, Xianping; Liu, Zhigang; Liu, Ya; Liu, Wanfu; Hong, Li

    2017-09-01

    In this study, a special section tunnel model was established by using FDS (Fire Dynamics Simulator). The influences of lope and curvature on smoke flow under natural ventilation have been studied. The results showed that under the condition of natural ventilation, the slope has some influences on the smoke flow in special section tunnel. The smoke spreading speed is accelerated along the upstream direction and decrease along the downstream direction due to buoyancy effect of slope. The steeper the tunnel, the more obvious the buoyancy effect. The curvature has little effect on the flow of flue gas.

  18. Terminal-shock and restart control of a Mach 2.5, axisymmetric, mixed compression inlet with 40 percent internal contraction. [wind tunnel tests

    Science.gov (United States)

    Baumbick, R. J.

    1974-01-01

    Results of experimental tests conducted on a supersonic, mixed-compression, axisymmetric inlet are presented. The inlet is designed for operation at Mach 2.5 with a turbofan engine (TF-30). The inlet was coupled to either a choked orifice plate or a long duct which had a variable-area choked exit plug. Closed-loop frequency responses of selected diffuser static pressures used in the terminal-shock control system are presented. Results are shown for Mach 2.5 conditions with the inlet coupled to either the choked orifice plate or the long duct. Inlet unstart-restart traces are also presented. High-response inlet bypass doors were used to generate an internal disturbance and also to achieve terminal-shock control.

  19. Does the graft-tunnel friction influence knee joint kinematics and biomechanics after anterior cruciate ligament reconstruction? A finite element study.

    Science.gov (United States)

    Wan, Chao; Hao, Zhixiu

    2018-02-01

    Graft tissues within bone tunnels remain mobile for a long time after anterior cruciate ligament (ACL) reconstruction. However, whether the graft-tunnel friction affects the finite element (FE) simulation of the ACL reconstruction is still unclear. Four friction coefficients (from 0 to 0.3) were simulated in the ACL-reconstructed joint model as well as two loading levels of anterior tibial drawer. The graft-tunnel friction did not affect joint kinematics and the maximal principal strain of the graft. By contrast, both the relative graft-tunnel motion and equivalent strain for the bone tunnels were altered, which corresponded to different processes of graft-tunnel integration and bone remodeling, respectively. It implies that the graft-tunnel friction should be defined properly for studying the graft-tunnel integration or bone remodeling after ACL reconstruction using numerical simulation.

  20. Study on the properties of porous magnetorheological elastomers under shock effect

    International Nuclear Information System (INIS)

    Ju, B X; Yu, M; Fu, J; Zheng, X; Yang, Q

    2013-01-01

    As a safe protector, buffer has been widely applied to engineering applications. The properties of cushion materials play a key role in the performance of the buffer under shock loading. Magnetorheological elastomers (MRE) are a kind of novel smart materials and show to have a controllable, field-dependent modulus, which have attracted increasing attentions and broad application prospects. This paper aims to fabricate a new kind of MRE, named as porous MRE, and study on the properties of porous MRE under shock effect in the presence of an external magnetic field. Three kinds of MRE samples based on polyurethane matrix were prepared without external magnetic field, and ammonium bicarbonate was used as foaming agent with content of 0 wt.%, 0.26 wt.%, 0.67 wt.%, respectively. The microstructures of the sample were observed by using a digital microscope, and image processing and analysis was applied to calculate the parameters of porous MRE. A sleeve structure and mass block were used to test the shock performance of porous MRE under shear mode, and an electromagnetic vibration and shock table was used to provide shock signal with half-sine shock signal. The results show that the content of foaming agent has an obvious influence on the microstructures of porous MRE. The porosity of the porous MRE samples increases with increasing of foaming agent content. Moreover, experimental results show that shock energy dissipation capacity is better than that of traditional MRE. This study is expected to provide guidance in the application of MRE in practical devices, such as in buffer devices.

  1. Comparative study of construction schemes for proposed LINAC tunnel for ADSS

    International Nuclear Information System (INIS)

    Parchani, G.; Suresh, N.

    2003-01-01

    Radiation shielded structures involve architectural, structural and radiation shielding design. In order to attenuate the radiation level to the permissible limits concrete has been recognized as a most versatile radiation shielding material and is being extensively used. Concrete in addition to radiation shielding properties possesses very good mechanical properties, which enables its use as a structural member. High-energy linac lab, which will generate radiation, needs very large thickness of concrete for shielding. The length of tunnel (1.00 kM) is one of the most important factors in finalizing construction scheme. In view of this, it becomes essential to explore alternate construction schemes for such structures to optimize the cost of construction. In this paper, various alternates for the construction of proposed linac tunnel have been studied

  2. Experimental Study on the Tensile Strength and Linear Expansion Coefficient of Air Tunnel Terrazzo Surface

    Directory of Open Access Journals (Sweden)

    Boping Li

    2015-01-01

    Full Text Available At present, studies on the surface tension of air tunnel terrazzo under wind load and how regularly it is affected by temperature are relatively less, and the measured results of the thermal expansion coefficient of terrazzo have not yet been given. In this paper, based on the top terrazzo surface structure of the inner wall of the wind tunnel, the tensile performance tests of terrazzo surface layer are conducted, while the thermal expansion coefficient of the six terrazzo test blocks were tested. The tests and analysis show that the construction of terrazzo surface, based on the proposed construction process, can effectively guarantee the reliable cement performance for the binding layer between mortar and concrete base layer, terrazzo surface layer and the cement mortar layer. And the thermal expansion coefficient of terrazzo can be valued at 1.06e-5/ºC.

  3. Atomic defects in monolayer WSe2 tunneling FETs studied by systematic ab initio calculations

    Science.gov (United States)

    Wu, Jixuan; Fan, Zhiqiang; Chen, Jiezhi; Jiang, Xiangwei

    2018-05-01

    Atomic defects in monolayer WSe2 tunneling FETs (TFETs) are studied through systematic ab initio calculations aiming at performance predictions and enhancements. The effects of various defect positions and different passivation atoms are characterized in WSe2 TFETs by rigorous ab initio quantum transport simulations. It is suggested that the Se vacancy (VSe) defect located in the gate-controlled channel region tends to increase the OFF current (I off), whereas it can be well suppressed by oxygen passivation. It is demonstrated that chlorine (Cl) passivation at the source-side tunneling region can largely suppress I off, leading to an impressively improved on–off ratio (I on/I off) compared with that without any defect. However, it is also observed that randomly positioned atomic defects tend to induce significant fluctuation of the TFET output. Further discussions are made with focus on the performance-variability trade-off for robust circuit design.

  4. Study of grain boundary tunneling in barium-titanate ceramic films

    CERN Document Server

    Wong, H; Poon, M C

    1999-01-01

    The temperature and the electric-field dependences of the current-voltage characteristics and the low-frequency noise of barium-titanate ceramic films are studied. An abnormal field dependence is observed in the resistivity of BaTiO sub 3 materials with a small average grain size. In addition, experiments show that the low-frequency noise behaviors are governed by grain-boundary tunneling at room temperature and by trapping-detrapping of grain-boundary states at temperatures above the Curie point. Physical models for the new observations are developed. Results suggest that grain-boundary tunneling of carriers is as important as the double Schottky barrier in the current conduction in BaTiO sub 3 materials with small grain sizes.

  5. Microsystem Aeromechanics Wind Tunnel

    Data.gov (United States)

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

  6. Tunneling of electrons via rotor–stator molecular interfaces: Combined ab initio and model study

    Energy Technology Data Exchange (ETDEWEB)

    Petreska, Irina, E-mail: irina.petreska@pmf.ukim.mk [Institute of Physics, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, PO Box 162, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Ohanesjan, Vladimir [Institute of Physics, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, PO Box 162, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Pejov, Ljupčo [Institute of Chemistry, Department of Physical Chemistry, Ss. Cyril and Methodius University, Arhimedova 5, P.O. Box 162, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Kocarev, Ljupčo [Macedonian Academy of Sciences and Arts, Krste Misirkov 2, PO Box 428, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Faculty of Computer Science and Engineering, Ss. Cyril and Methodius University, Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of)

    2016-07-01

    Tunneling of electrons through rotor–stator anthracene aldehyde molecular interfaces is studied with a combined ab initio and model approach. Molecular electronic structure calculated from first principles is utilized to model different shapes of tunneling barriers. Together with a rectangular barrier, we also consider a sinusoidal shape that captures the effects of the molecular internal structure more realistically. Quasiclassical approach with the Simmons’ formula for current density is implemented. Special attention is paid on conformational dependence of the tunneling current. Our results confirm that the presence of the side aldehyde group enhances the interesting electronic properties of the pure anthracene molecule, making it a bistable system with geometry dependent transport properties. We also investigate the transition voltage and we show that conformation-dependent field emission could be observed in these molecular interfaces at realistically low voltages. The present study accompanies our previous work where we investigated the coherent transport via strongly coupled delocalized orbital by application of Non-equilibrium Green’s Function Formalism.

  7. Study on the measures of tunnels side-crossing bridge based on sheltering effects of isolation piles

    Science.gov (United States)

    Tang, Jian; Liu, Jun yan; Liu, Yan

    2017-08-01

    Based on the transit line 3, we studied the effect of the bridge piles crossed closely from the side by the shield tunnel. Using the three-dimensional finite element numerical analysis software Midas GTS/NX, we analyzed the effect of shield tunnel on pile deformation, statistics are obtained that under the condition of pile, subgrade reinforcement and ground changes. The calculation results show that in the condition of reinforcement, the new tunnel shield crossing through the pile caused longitudinal disturbance of the tunnel surrounding strata along the tunnel, where the soil over the area is within a certain range of pile and settlement deformation of surface subsidence occurs, changing the surface roughly to the shape of “V”. The maximum value appears above the shield tunnel and the value is high. In combination with engineering geology, hydrogeology and environment factors, this paper adopted isolation pile reinforcement to the pile, and the simulated results show that, pile settlement was significantly reduced under the condition of pile reinforcement. The calculation results show the rationality of the reinforcement scheme to a certain extent, which provides a theoretical basis for the similar tunnel.

  8. Safety Evaluation of the Lighting at the Entrance of a Very Long Road Tunnel: A Case Study in Ilam.

    Science.gov (United States)

    Mehri, Ahmad; Hajizadeh, Roohalah; Farhang Dehghan, Somayeh; Nassiri, Parvin; Jafari, Sayed Mohammad; Taheri, Fereshteh; Zakerian, Seyed Abolfazl

    2017-06-01

    At the entrance of a tunnel, reflection of sunlight from the surrounding environment and a lack of adequate lighting usually cause some vision problems. The purpose of this study was to perform a safety evaluation of lighting on a very long road in Ilam, Iran. The average luminance was measured using a luminance meter (model S3; Hagner, Solna, Sweden). A camera (model 108, 35-mm single-lens reflex; Yashica, Nagano, Japan) was used to take photographs of the safe stopping distance from the tunnel entrance. Equivalent luminance was determined according to the Holliday polar diagram. Considering the average luminance at the tunnel entrance (116.7 cd/m 2 ) and using Adrian's equation, the safe level of lighting at the entrance of the tunnel was determined to be 0.7. A comparison between the results of the safe levels of lighting at the entrance of the tunnel and the De Boer scale showed that the phenomenon of black holes is created at the tunnel entrance. This may lead to a misadaptation of the drivers' eyes to the change in luminance level at the entrance of the tunnel, thereby increasing the risk of road accidents in this zone.

  9. Assessment of CFD Capability for Hypersonic Shock Wave Laminar Boundary Layer Interactions

    OpenAIRE

    Mehrnaz Rouhi Youssefi; Doyle Knight

    2017-01-01

    The goal of this study is to assess CFD capability for the prediction of shock wave laminar boundary layer interactions at hypersonic velocities. More specifically, the flow field over a double-cone configuration is simulated using both perfect gas and non-equilibrium Navier–Stokes models. Computations are compared with recent experimental data obtained from measurements conducted in the LENS XX (Large Energy National Shock Expansion Tunnel Version 2) at the Calspan University of Buffalo Rese...

  10. Extracorporeal shock wave lithotripsy for gallbladder stones - an experimental and clinical study -

    International Nuclear Information System (INIS)

    Kim, Kun Sang; Park, Sil Moo; Lee, Jung Hyo; Kim, Young Goo; Song, Kounn Sik; Lee, Kwan Seh; Lee, Jong Beum; Kim, Sang Joon; Chang, Sun Taik

    1988-01-01

    Although many alternative treatment technics have been proposed recently for gallstone to substitute cholecystectomy, the extracorporeal shock wave lithotripsy (ESWL) for gallbladder stones has rarely been tried. We have carried out a series of experiments to evaluate how effective the ESWL for gallbladder stones in and how safe this procedure is. At first, in vitro shock were application was carried out to 10 gallbladder stones which were obtained from human gallbladder. Secondly, gallbladder stones were implanted to canine gallbladder and treated with shock wave. Lastly, a total of 41 volunteers with confirmed gallbladder stones were treated with shock wave and combined oral administration of ursodeoxycholic acid. In the in vitro experiment, all of the 10 gallstones were fragmented with variable firing rates and duration. In animal experiment, the implanted stones were successfully fragmented and the organs included in the pathway of shock wave were proved to be intact histologically. In human study, complete disappearance of gallstones was noted in 78.6% of patients with single radiolucent gallbladder stones, smaller than 2.5cm in the longest diameter. Two patients underwent cholecystectomy after ESWL due to sudden colic attack. One patient had experienced an episode of mild transient obstructive jaundice. It may be concluded that the ESWL for gallbladder stones is an effective and safe method of treatment of gallbladder stones in the selected cases, for example, small radiolucent stones, and the further study is needed to establish improved technology of the ESWL for gallbladder stones.

  11. Extracorporeal shock wave lithotripsy for gallbladder stones - an experimental and clinical study -

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kun Sang; Park, Sil Moo; Lee, Jung Hyo; Kim, Young Goo; Song, Kounn Sik; Lee, Kwan Seh; Lee, Jong Beum; Kim, Sang Joon; Chang, Sun Taik [Chung-Ang University College of Medicine, Seoul (Korea, Republic of)

    1988-08-15

    Although many alternative treatment technics have been proposed recently for gallstone to substitute cholecystectomy, the extracorporeal shock wave lithotripsy (ESWL) for gallbladder stones has rarely been tried. We have carried out a series of experiments to evaluate how effective the ESWL for gallbladder stones in and how safe this procedure is. At first, in vitro shock were application was carried out to 10 gallbladder stones which were obtained from human gallbladder. Secondly, gallbladder stones were implanted to canine gallbladder and treated with shock wave. Lastly, a total of 41 volunteers with confirmed gallbladder stones were treated with shock wave and combined oral administration of ursodeoxycholic acid. In the in vitro experiment, all of the 10 gallstones were fragmented with variable firing rates and duration. In animal experiment, the implanted stones were successfully fragmented and the organs included in the pathway of shock wave were proved to be intact histologically. In human study, complete disappearance of gallstones was noted in 78.6% of patients with single radiolucent gallbladder stones, smaller than 2.5cm in the longest diameter. Two patients underwent cholecystectomy after ESWL due to sudden colic attack. One patient had experienced an episode of mild transient obstructive jaundice. It may be concluded that the ESWL for gallbladder stones is an effective and safe method of treatment of gallbladder stones in the selected cases, for example, small radiolucent stones, and the further study is needed to establish improved technology of the ESWL for gallbladder stones.

  12. Numerical Study of Richtmyer-Meshkov Instability with Re-Shock

    Science.gov (United States)

    Wong, Man Long; Livescu, Daniel; Lele, Sanjiva

    2017-11-01

    The interaction of a Mach 1.45 shock wave with a perturbed planar interface between two gases with an Atwood number 0.68 is studied through 2D and 3D shock-capturing adaptive mesh refinement (AMR) simulations with physical diffusive and viscous terms. The simulations have initial conditions similar to those in the actual experiment conducted by Poggi et al. [1998]. The development of the flow and evolution of mixing due to the interactions with the first shock and the re-shock are studied together with the sensitivity of various global parameters to the properties of the initial perturbation. Grid resolutions needed for fully resolved and 2D and 3D simulations are also evaluated. Simulations are conducted with an in-house AMR solver HAMeRS built on the SAMRAI library. The code utilizes the high-order localized dissipation weighted compact nonlinear scheme [Wong and Lele, 2017] for shock-capturing and different sensors including the wavelet sensor [Wong and Lele, 2016] to identify regions for grid refinement. First and third authors acknowledge the project sponsor LANL.

  13. Shock wave energy dissipation behavior (SWED) in Network forming ionic liquids (NILs): A Molecular dynamics study

    Science.gov (United States)

    Guda Vishnu, Karthik; Strachan, Alejandro

    2017-06-01

    SWED materials play a crucial role in protecting both personnel and structures in close proximity to blasts or ballistic impact. Exposure to shock waves with intensities as low as 1 MPa can cause brain injury in personnel and, hence, it is extremely important to understand the mechanisms operating in SWED materials and help design improved formulations. Recent experimental studies show that NILs containing di-ammonium cations and citrate anions with glass transition temperatures (Tg) below room temperature exhibit shockwave absorption characteristics that outperform polyurea (PU), a benchmark SWED assessment material. The experimentalists further hypothesized that the increased SWED ability in NILs with longer side chains (in di-ammonium cation) is due to a permanent structural ordering and nano-scale segregation. We use molecular dynamics simulations with the Dreiding force field to study shock propagation mechanisms in NILs. Shock propagation mechanisms in these materials are explored by performing both Hugoniostat and large scale non-equilibrium molecular dynamics (NEMD) simulations at 300 K. The simulation results show that the NIL 5-6 (5 C atoms (back bone) and 6 C atoms (side chain)) attenuates shocks better than NIL 5-3 (3 C atoms (side chain) and higher Tg) and PMMA in agreement with experimental observation. The simulations show that under shock loading the structures lose long range order; we find no evidence of nano-segregation nor or permanent structural changes.

  14. Vortex ring formation at the open end of a shock tube: A particle image velocimetry study

    Science.gov (United States)

    Arakeri, J. H.; Das, D.; Krothapalli, A.; Lourenco, L.

    2004-04-01

    The vortex ring generated subsequent to the diffraction of a shock wave from the open end of a shock tube is studied using particle image velocimetry. We examine the early evolution of the compressible vortex ring for three-exit shock Mach numbers, 1.1, 1.2, and 1.3. For the three cases studied, the ring formation is complete at about tUb/D=2, where t is time, Ub is fluid velocity behind shock as it exits the tube and D is tube diameter. Unlike in the case of piston generated incompressible vortex rings where the piston velocity variation with time is usually trapezoidal, in the shock-generated vortex ring case the exit fluid velocity doubles from its initial value Ub before it slowly decays to zero. At the end of the ring formation, its translation speed is observed to be about 0.7 Ub. During initial formation and propagation, a jet-like flow exists behind the vortex ring. The vortex ring detachment from the tailing jet, commonly referred to as pinch-off, is briefly discussed.

  15. Percutaneous Ultrasound-Guided Carpal Tunnel Release: Study Upon Clinical Efficacy and Safety

    Energy Technology Data Exchange (ETDEWEB)

    Petrover, David, E-mail: dpetrover@yahoo.fr; Silvera, Jonathan, E-mail: silvera.jonathan@gmail.com [Imagerie Médicale Paris Centre Bachaumont-clinique Blomet RamsayGDS, Department of Interventional Radiology (France); Baere, Thierry De, E-mail: Debaere@igr.fr [Gustave Roussy Institute (France); Vigan, Marie, E-mail: marie.vigan@gmail.com [Association pour la recherche en chirurgie de l’épaule et du coude, clinique Drouot (France); Hakimé, Antoine, E-mail: thakime@yahoo.com [Imagerie Médicale Paris Centre Bachaumont-clinique Blomet RamsayGDS, Department of Interventional Radiology (France)

    2017-04-15

    ObjectivesTo evaluate the feasibility and 6 months clinical result of sectioning of the transverse carpal ligament (TCL) and median nerve decompression after ultra-minimally invasive, ultrasound-guided percutaneous carpal tunnel release (PCTR) surgery.MethodsConsecutive patients with carpal tunnel syndrome were enrolled in this descriptive, open-label study. The procedure was performed in the interventional radiology room. Magnetic resonance imaging was performed at baseline and 1 month. The Boston Carpal Tunnel Questionnaire was administered at baseline, 1, and 6 months.Results129 patients were enrolled. Significant decreases in mean symptom severity scores (3.3 ± 0.7 at baseline, 1.7 ± 0.4 at Month 1, 1.3 ± 0.3 at Month 6) and mean functional status scores (2.6 ± 1.1 at baseline, 1.6 ± 0.4 at Month 1, 1.3 ± 0.5 at Month 6) were noted. Magnetic resonance imaging showed a complete section of all TCL and nerve decompression in 100% of patients. No complications were identified.ConclusionsUltrasound-guided PCTR was used successfully to section the TCL, decompress the median nerve, and reduce self-reported symptoms.

  16. A model study of tunneling conductance spectra of ferromagnetically ordered manganites

    Science.gov (United States)

    Panda, Saswati; Kar, J. K.; Rout, G. C.

    2018-02-01

    We report here the interplay of ferromagnetism (FM) and charge density wave (CDW) in manganese oxide systems through the study of tunneling conductance spectra. The model Hamiltonian consists of strong Heisenberg coupling in core t2g band electrons within mean-field approximation giving rise to ferromagnetism. Ferromagnetism is induced in the itinerant eg electrons due to Kubo-Ohata type double exchange (DE) interaction among the t2g and eg electrons. The charge ordering (CO) present in the eg band giving rise to CDW interaction is considered as the extra-mechanism to explain the colossal magnetoresistance (CMR) property of manganites. The magnetic and CDW order parameters are calculated using Zubarev's Green's function technique and solved self-consistently and numerically. The eg electron density of states (DOS) calculated from the imaginary part of the Green's function explains the experimentally observed tunneling conductance spectra. The DOS graph exhibits a parabolic gap near the Fermi energy as observed in tunneling conductance spectra experiments.

  17. Percutaneous Ultrasound-Guided Carpal Tunnel Release: Study Upon Clinical Efficacy and Safety

    International Nuclear Information System (INIS)

    Petrover, David; Silvera, Jonathan; Baere, Thierry De; Vigan, Marie; Hakimé, Antoine

    2017-01-01

    ObjectivesTo evaluate the feasibility and 6 months clinical result of sectioning of the transverse carpal ligament (TCL) and median nerve decompression after ultra-minimally invasive, ultrasound-guided percutaneous carpal tunnel release (PCTR) surgery.MethodsConsecutive patients with carpal tunnel syndrome were enrolled in this descriptive, open-label study. The procedure was performed in the interventional radiology room. Magnetic resonance imaging was performed at baseline and 1 month. The Boston Carpal Tunnel Questionnaire was administered at baseline, 1, and 6 months.Results129 patients were enrolled. Significant decreases in mean symptom severity scores (3.3 ± 0.7 at baseline, 1.7 ± 0.4 at Month 1, 1.3 ± 0.3 at Month 6) and mean functional status scores (2.6 ± 1.1 at baseline, 1.6 ± 0.4 at Month 1, 1.3 ± 0.5 at Month 6) were noted. Magnetic resonance imaging showed a complete section of all TCL and nerve decompression in 100% of patients. No complications were identified.ConclusionsUltrasound-guided PCTR was used successfully to section the TCL, decompress the median nerve, and reduce self-reported symptoms.

  18. Numerical studies of electron dynamics in oblique quasi-perpendicular collisionless shock waves

    International Nuclear Information System (INIS)

    Liewer, P.C.; Decyk, V.K.; Dawson, J.M.; Lembege, B.

    1991-01-01

    Linear and nonlinear electron damping of the whistler precursor wave train to low Mach number quasi-perpendicular oblique shocks is studied using a one-dimensional electromagnetic plasma simulation code with particle electrons and ions. In some parameter regimes, electrons are observed to trap along the magnetic field lines in the potential of the whistler precursor wave train. This trapping can lead to significant electron heating in front of the shock for β e (∼10% or less). Use of the 64-processor Caltech/JPL Mark IIIfp hypercube concurrent computer has enables us to make long runs using realistic mass ratios (m i /m e = 1,600) in the full particle in-cell code and thus simulate shock parameter regimes and phenomena not previously studied numerically

  19. ESTIMATION OF THE SPECIFIC ENERGY OF TUNNEL BORING MACHINE USING POST-FAILURE BEHAVIOUR OF ROCK MASS.CASE STUDY: KARAJ-TEHRAN WATER CONVEYANCE TUNNEL IN IRAN

    Directory of Open Access Journals (Sweden)

    MAJID MIRAHMADI

    2017-09-01

    Full Text Available Performance prediction of tunnel boring machines (TBM is the most important factor for successful tunnel excavation projects. The specific energy (SE of TBM, defined as the amount of energy required to excavate a unit volume of rock, is one of the critical parameters used for performance prediction of these machines. Estimation of SE is very useful to design the drilling project because it is a function of many parameters such as rock mass behaviour, machine properties and project parameters. Several methods are used to estimate this parameter, such as experimental, empirical and numerical. The aim of this study is to estimate the SE considering the postfailure behaviour of rock mass. For this reason, based on the actual data from Karaj-Tehran water conveyance tunnel, a new empirical method is proposed to estimate the SE using the drop-to-deformation modulus ratio (λ. Based on the statistical analysis, the relation between the SE and λ is estimated. It is clear that the amplitude of λ, is high and to increase the correlation between mentioned parameters, the classification of data is performed. All data is classified in three classes as very weak (GSI75. Also a statistical analysis is performed to estimate the SE using the mentioned parameter (λ in any class. The result shows that there is a direct relation between both parameters and the best correlation is achieved. So, the best equations are proposed to estimate SE using λ, considering the post failure behaviour of rock mass.

  20. Laboratory studies of magnetized collisionless flows and shocks using accelerated plasmoids

    Science.gov (United States)

    Weber, T. E.; Smith, R. J.; Hsu, S. C.

    2015-11-01

    Magnetized collisionless shocks are thought to play a dominant role in the overall partition of energy throughout the universe, but have historically proven difficult to create in the laboratory. The Magnetized Shock Experiment (MSX) at LANL creates conditions similar to those found in both space and astrophysical shocks by accelerating hot (100s of eV during translation) dense (1022 - 1023 m-3) Field Reversed Configuration (FRC) plasmoids to high velocities (100s of km/s); resulting in β ~ 1, collisionless plasma flows with sonic and Alfvén Mach numbers of ~10. The FRC subsequently impacts a static target such as a strong parallel or anti-parallel (reconnection-wise) magnetic mirror, a solid obstacle, or neutral gas cloud to create shocks with characteristic length and time scales that are both large enough to observe yet small enough to fit within the experiment. This enables study of the complex interplay of kinetic and fluid processes that mediate cosmic shocks and can generate non-thermal distributions, produce density and magnetic field enhancements much greater than predicted by fluid theory, and accelerate particles. An overview of the experimental capabilities of MSX will be presented, including diagnostics, selected recent results, and future directions. Supported by the DOE Office of Fusion Energy Sciences under contract DE-AC52-06NA25369.

  1. A comparative study on laser induced shock cleaning of radioactive contaminants in air and water

    Science.gov (United States)

    Kumar, Aniruddha; Prasad, Manisha; Bhatt, R. B.; Behere, P. G.; Biswas, D. J.

    2018-03-01

    Efficient removal of Uranium-di-oxide (UO2) particulates from stainless steel surface was effected by Nd-YAG laser induced plasma shock waves in air as well as in water environment. The propagation velocity of the generated shock wave was measured by employing the photo-acoustic probe deflection method. Monitoring of the alpha activity of the sample with a ZnS (Ag) scintillation detector before and after the laser exposure allowed the estimation of decontamination efficiency defined as the percentage removal of the initial activity. Experiments were carried out to study the effect of laser pulse energy, number of laser exposures, orientation of the sample, the separation between the substrate surface and the onset point of the shock wave on the de-contamination efficiency. The most optimised cleaning was found to occur when the laser beam impinged normally on the sample that was immersed in water and placed at a distance of ∼0.7 mm from the laser focal spot. Analysis of the cleaned surface by optical microscopes established that laser induced shock cleaning in no way altered the surface property. The shock force generated in both air and water has been estimated theoretically and has been found to exceed the Van der Waal's binding force for spherical contaminant particulate.

  2. A study on early microstructural changes in the rabbit gallbladder induced by shock waves

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Eun Oak [Hong-Sung Koryo Hospital, Hongsung (Korea, Republic of); Shim, Hyung Jin; Kim, Kun Sang; Ryo, Dae Sik; Choi, Yun Sun; Song, In Sup; Kim, Young Koo [College of Medicine, Chung Ang University, Seoul (Korea, Republic of)

    1994-05-15

    In order to evaluate microstructural changes after shock wave exposure, gross, light microscopic and transmission electron microscopic findings were analyzed with rabbit gallbladders. A preliminary study(2 rabbits) was performed to determine the dosage intensity of shock waves needed to inflict damage, using a EDAP LT 01 piezoelectric extracorporeal shock wave lothotriptor. The Gallbladders of three different groups of rabbits were given shock waves of various intensity. A storage value of 100, 50, 25 at rate of 20/sec under 80% power were given to group I (4 rabbits), group II (4 rabbits), and group III (3 rabbits), respectively. The rabbits were sacrificed 6-12 hours later. The observed pathologic changes in the transmission electron microscopy were vaculization of cytoplasm and swelling of epithelial cells with dilatation and structural alteration of intracellular organelles, especially endoplasmic reticulum. Cell membrane rupture and necrosis were observed at the markedly affected area. The structural changes of intracellular organelles were minimally found at a storage value of 25. However, above pathologic changes with dilatation and structural alterations of endoplasmic reticulums were more profound at value of 100. Early histologic changes induced by shocked waves are dose dependent and findings of cellular damage caused by ESWL might be explained as above.

  3. A prospective study of prognostic factors for duration of sick leave after endoscopic carpal tunnel release

    Directory of Open Access Journals (Sweden)

    Dalsgaard Jesper

    2009-11-01

    Full Text Available Abstract Background Endoscopic carpal tunnel release with a single portal technique has been shown to reduce sick leave compared to open carpal tunnel release, claiming to be a less invasive procedure and reducing scar tenderness leading to a more rapid return to work, and the purpose of this study was to identify prognostic factors for prolonged sick leave after endoscopic carpal tunnel release in a group of employed Danish patients. Methods The design was a prospective study including 75 employed patients with carpal tunnel syndrome operated with ECTR at two hospitals. The mean age was 46 years (SD 10.1, the male/female ratio was 0.42, and the mean preoperative duration of symptoms 10 months (range 6-12. Only 21 (28% were unable to work preoperatively and mean sick leave was 4 weeks (range 1-4. At base-line and at the 3-month follow-up, a self-administered questionnaire was collected concerning physical, psychological, and social circumstances in relation to the hand problem. Data from a nerve conduction examination were collected at baseline and at the 3-month follow-up. Significant prognostic factors were identified through multiple logistic regression analysis. Results After the operation, the mean functional score was reduced from 2.3 to 1.4 (SD 0.8 and the mean symptom score from 2.9 to 1.5 (SD 0.7. The mean sick leave from work after the operation was 19.8 days (SD 14.3. Eighteen patients (24% had more than 21 days of sick leave. Two patients (3% were still unable to work after 3 months. Significant prognostic factors in the multivariate analysis for more than 21 days of postoperative sick leave were preoperative sick leave, blaming oneself for the hand problem and a preoperative distal motor latency. Conclusion Preoperative sick leave, blaming oneself for the hand problem, and a preoperative distal nerve conduction motor latency were prognostic factors for postoperative work absence of more than 21 days. Other factors may be important

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

    International Nuclear Information System (INIS)

    Yanting Chang; Swindell, Robert; Bogdanoff, Ingvar; Lindstroem, Beatrice; Termen, Jens; Starsec, Peter

    2005-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-04-01

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

  6. A study on early microstructural changes in the rabbit kidney induced by shock waves

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Kyung Soo [Sung Ae Hospital, Seoul (Korea, Republic of); Shim, Hyung Jin; Kim, Kun Sang; Song, In Sup; Lee, Yong Chul; Song, Kei Yong [College of Medicine, Chung Ang University, Seoul (Korea, Republic of)

    1993-07-15

    Many reports have been published on the tissue damage of a shock wave with respect to histopathological changes in light microscopy and various imaging modalities. However, the studies on the electron microscopic findings and cause of renal functional change such as parenchymal obstructive pattern following extracorporeal shock wave lithotripsy (ESWL) have not been elucidated. In order to evaluate the microstructural changes after shock wave exposure, gross, light microscopic and transmission electron microscopic findings were analyzed with rabbit kidneys. Preliminary study (n=2) was performed to determine the dosage intensity of shock waves to inflict damage, using a EDAP LT 01 piezoelectric extracorporeal shock wave lithotriptor. A shock wave of various intensities were given to the left kidneys of 3 different groups of rabbits. Storage of value of 100, 50, 25 at rate of 20/sec under 87% power were given to group I (n=4), group II (n=4), and group III (n=3) respectively. The right kidneys were preserved as the control group. The rabbits were killed 6-12 hour later. In gross, there were a few subcapsular hemorrhage foci and mild congestion of corticomedullary junction without a large hematoma formation. No significant differences were noted between each group. Light microscopic findings were mainly hydropic changes in the proximal convoluted tubules and congestion without significant necrotic changes. The observed pathologic changes in the transmission electron microscopy were vacuolization of cytoplasm with swelling of epithelial cells especially porximal convoluted tubules. There were also tubular obstruction due to swelling and desquamation of epithelial cells into tubular lumen. The structural changes of intracellular organelles were not found at storage values of 25 and 50. But dilatation and structural alterations of endoplasmic reticulums were noted at value of 100 with cell membrane rupture. The findings of this study suggest that tubular obstructions with

  7. Study on the Shock-transmission Mechanism of Stock Price among China, Russia and India

    Directory of Open Access Journals (Sweden)

    Menggen Chen

    2014-08-01

    Full Text Available Researchers pay more and more attention on the price comovement-effect among international stock markets. This paper deals with the transmission mechanism of price shocks among three stock markets of China, Russia and India, with a sample of weekly returns. The results showed that the price fluctuation of each market has an influence on other markets, although the price behavior is significantly independent. The impact of external price innovations will last 5 or 6 weeks usually and disappear after about 8 weeks. The pattern of transmission-mechanism for the price shocks is very different from each other. Besides, a further study revealed that the influence of external shocks on the domestic stock price increased significantly among the three markets after the 2008 international financial crisis.

  8. Initial crystallographic studies of a small heat-shock protein from Xylella fastidiosa

    International Nuclear Information System (INIS)

    Tada, Susely F. S.; Saraiva, Antonio Marcos; Lorite, Gabriela S.; Rosselli-Murai, Luciana K.; Pelloso, Alexandre César; Santos, Marcelo Leite dos; Trivella, Daniela B. B.; Cotta, Mônica A.; Souza, Anete Pereira de; Aparicio, Ricardo

    2012-01-01

    Initial crystallographic studies of the X. fastidiosa small heat-shock protein HSP17.9 are reported. The ORF XF2234 in the Xylella fastidiosa genome was identified as encoding a small heat-shock protein of 17.9 kDa (HSP17.9). HSP17.9 was found as one of the proteins that are induced during X. fastidiosa proliferation and infection in citrus culture. Recombinant HSP17.9 was crystallized and surface atomic force microscopy experiments were conducted with the aim of better characterizing the HSP17.9 crystals. X-ray diffraction data were collected at 2.7 Å resolution. The crystal belonged to space group P4 3 22, with unit-cell parameters a = 68.90, b = 68.90, c = 72.51 Å, and is the first small heat-shock protein to crystallize in this space group

  9. Laser driven shock wave experiments for equation of state studies at megabar pressures

    International Nuclear Information System (INIS)

    Pant, H C; Shukla, M; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K

    2002-01-01

    We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 μm wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments

  10. High speed photography for studying the shock wave propagation at high Mach numbers through a reflection nozzle

    International Nuclear Information System (INIS)

    Zaytsev, S.G.; Lazareva, E.V.; Mikhailova, A.V.; Nikolaev-Kozlov, V.L.; Chebotareva, E.I.

    1979-01-01

    Propagation of intensive shock waves with a temperature of about 1 eV has been studied in a two-dimensional reflection nozzle mounted at the exit of a shock tube. The Toepler technique has been involved along with the interference scheme with a laser light source allowing the multiple-frame recording to be done. Density distribution in the nozzle as well as the wave pattern occurring at the shock propagation are presented. (author)

  11. Experimental and numerical studies of various thermal sleeves subjected to severe cyclic thermal shocks

    International Nuclear Information System (INIS)

    Masson, J.C.; Moinereau, D.

    1990-01-01

    During the first operating years of nuclear power plants of different countries, damage was encountered on thermal sleeves used as nozzle protection. Following this discovery studies were initiated to determine the causes and to find solutions. At first a problem of vibration was found and easily solved by reducing gaps and reinforcing the welding of the sleeves. But preliminary tests with cyclic thermal shocks showed a risk of fatigue crack initiation and propagation both in the sleeve fixation and in the nozzle. Therefore a large research and development program was led principally by EDF laboratories of Les Renardieres, to demonstrate the absence of nocivity of thermal shocks during the plants life time [fr

  12. Tunneling works. Tunnel koji

    Energy Technology Data Exchange (ETDEWEB)

    Higo, M [Hazam Gumi, Ltd., Tokyo (Japan)

    1991-10-25

    A mountain tunneling method for rock-beds used to be applied mainly to construction works in the mountains under few restrictions by environmental problems. However, construction works near residential sreas have been increasing. There are such enviromental problems due to tunneling works as vibration, noise, lowering of ground-water level, and influences on other structures. This report mainly describes the measurement examples of vibration and noise accompanied with blasting and the effects of the measures to lessen such influences. When the tunneling works for the railroad was carried out on the natural ground mainly composed of basalt, vibration of the test blasting was measured at three stations with piezoelectric accelerometers. Then, ordinary blasting, mutistage blasting, and ABM blasting methods were used properly besed on the above results, and only a few complaints were made. In the different works, normal noise and low-frequency sound were mesured at 22 stations around the pit mouth. As countermeasures for noise, sound-proof sheets, walls, and single and double doors were installed and foundto be effective. 1 ref., 6 figs., 1 tab.

  13. A study of inelastic electron-phonon interactions on tunneling magnetoresistance of a nano-scale device

    International Nuclear Information System (INIS)

    Modarresi, M.; Roknabadi, M.R.; Shahtahmasbi, N.; Vahedi Fakhrabad, D.; Arabshahi, H.

    2011-01-01

    In this research, we have studied the effect of inelastic electron-phonon interactions on current-voltage characteristic and tunneling magnetoresistance of a polythiophene molecule that is sandwiched between two cobalt electrodes using modified Green's function method as proposed by Walczak. The molecule is described with a modified Su-Schrieffer-Heeger Hamiltonian. The ground state of the molecule is obtained by Hellman-Feynman theorem. Electrodes are described in the wide-band approximation and spin-flip is neglected during conduction. Our calculation results show that with increase in voltage the currents increase and tunneling magnetoresistance decreases. Change in tunneling magnetoresistance due to inelastic interactions is limited in a small bias voltage interval and can be neglected in the other bias voltages. -- Research Highlights: →We investigate the effect of inelastic interaction on transport properties. →Due to inelastic interactions tunneling magnetoresistance decreases. →Decrease in TMR is restricted in a small voltage interval.

  14. A simulation study of the reaction of human heart to biphasic electrical shocks

    Directory of Open Access Journals (Sweden)

    Seemann Gunnar

    2004-06-01

    Full Text Available Abstract Background This article presents a study, which examines the effects of biphasic electrical shocks on human ventricular tissue. The effects of this type of shock are not yet fully understood. Animal experiments showed the superiority of biphasic shocks over monophasic ones in defibrillation. A mathematical computer simulation can increase the knowledge of human heart behavior. Methods The research presented in this article was done with different models representing a three-dimensional wedge of ventricular myocardium. The electrophysiology was described with Priebe-Beuckelmann model. The realistic fiber twist, which is specific to human myocardium was included. Planar electrodes were placed at the ends of the longest side of the virtual cardiac wedge, in a bath medium. They were sources of electrical shocks, which varied in magnitude from 0.1 to 5 V. In a second arrangement ring electrodes were placed directly on myocardium for getting a better view on secondary electrical sources. The electrical reaction of the tissue was generated with a bidomain model. Results The reaction of the tissue to the electrical shock was specific to the initial imposed characteristics. Depolarization appeared in the first 5 ms in different locations. A further study of the cardiac tissue behavior revealed, which features influence the response of the considered muscle. It was shown that the time needed by the tissue to be totally depolarized is much shorter when a biphasic shock is applied. Each simulation ended only after complete repolarization was achieved. This created the possibility of gathering information from all states corresponding to one cycle of the cardiac rhythm. Conclusions The differences between the reaction of the homogeneous tissue and a tissue, which contains cleavage planes, reveals important aspects of superiority of biphasic pulses. ...

  15. Reliability analysis of idealized tunnel support system using probability-based methods with case studies

    NARCIS (Netherlands)

    Gharouni-Nik, M.; Naeimi, M.; Ahadi, S.; Alimoradi, Z.

    2014-01-01

    In order to determine the overall safety of a tunnel support lining, a reliability-based approach is presented in this paper. Support elements in jointed rock tunnels are provided to control the ground movement caused by stress redistribution during the tunnel drive. Main support elements contribute

  16. Study of the tunnelling initiated leakage current through the carbon nanotube embedded gate oxide in metal oxide semiconductor structures

    International Nuclear Information System (INIS)

    Chakraborty, Gargi; Sarkar, C K; Lu, X B; Dai, J Y

    2008-01-01

    The tunnelling currents through the gate dielectric partly embedded with semiconducting single-wall carbon nanotubes in a silicon metal-oxide-semiconductor (MOS) structure have been investigated. The application of the gate voltage to such an MOS device results in the band bending at the interface of the partly embedded oxide dielectric and the surface of the silicon, initiating tunnelling through the gate oxide responsible for the gate leakage current whenever the thickness of the oxide is scaled. A model for silicon MOS structures, where carbon nanotubes are confined in a narrow layer embedded in the gate dielectric, is proposed to investigate the direct and the Fowler-Nordheim (FN) tunnelling currents of such systems. The idea of embedding such elements in the gate oxide is to assess the possibility for charge storage for memory device applications. Comparing the FN tunnelling onset voltage between the pure gate oxide and the gate oxide embedded with carbon nanotubes, it is found that the onset voltage decreases with the introduction of the nanotubes. The direct tunnelling current has also been studied at very low gate bias, for the thin oxide MOS structure which plays an important role in scaling down the MOS transistors. The FN tunnelling current has also been studied with varying nanotube diameter

  17. Dysprosium disilicide nanostructures on silicon(001) studied by scanning tunneling microscopy and transmission electron microscopy

    International Nuclear Information System (INIS)

    Ye Gangfeng; Nogami, Jun; Crimp, Martin A.

    2006-01-01

    The microstructure of self-assembled dysprosium silicide nanostructures on silicon(001) has been studied by scanning tunneling microscopy and transmission electron microscopy. The studies focused on nanostructures that involve multiple atomic layers of the silicide. Cross-sectional high resolution transmission electron microscopy images and fast Fourier transform analysis showed that both hexagonal and orthorhombic/tetragonal silicide phases were present. Both the magnitude and the anisotropy of lattice mismatch between the silicide and the substrate play roles in the morphology and epitaxial growth of the nanostructures formed

  18. Experimental Study on RFID Antenna Reading Areas in a Tunnel System

    Directory of Open Access Journals (Sweden)

    Kai Kordelin

    2017-01-01

    Full Text Available We study optimized antenna reading area mappings for a radiofrequency identification- (RFID- based access monitoring system, used in an underground nuclear waste storage facility. We shortly introduce the access monitoring system developed for the ONKALO tunnel in Finland and describe the antenna mounting points as well as the research area. Finally, we study the measurement results of the antenna reading areas and factors that affect the reading area size. Based on our results, in addition to antenna location and direction, absorption to obstacles, reflections, diffraction, scattering, and refraction affect the antenna reading area.

  19. Disseminated intravascular coagulation or acute coagulopathy of trauma shock early after trauma? A prospective observational study

    DEFF Research Database (Denmark)

    Johansson, Per Ingemar; Sorensen, Anne Marie; Perner, Anders

    2011-01-01

    ABSTRACT: INTRODUCTION: It is debated whether the early trauma induced coagulopathy (TIC) in severely injured patients reflects disseminated intravascular coagulation (DIC) with a fibrinolytic phenotype, acute coagulopathy of trauma shock (ACoTS) or yet other entities. This study investigated the...

  20. Predictive value of the baseline electrocardiogram ST-segment pattern in cardiogenic shock: Results from the CardShock Study.

    Science.gov (United States)

    Javanainen, Tuija; Tolppanen, Heli; Lassus, Johan; Nieminen, Markku S; Sionis, Alessandro; Spinar, Jindrich; Silva-Cardoso, José; Greve Lindholm, Matias; Banaszewski, Marek; Harjola, Veli-Pekka; Jurkko, Raija

    2018-05-30

    The most common aetiology of cardiogenic shock (CS) is acute coronary syndrome (ACS), but even up to 20%-50% of CS is caused by other disorders. ST-segment deviations in the electrocardiogram (ECG) have been investigated in patients with ACS-related CS, but not in those with other CS aetiologies. We set out to explore the prevalence of different ST-segment patterns and their associations with the CS aetiology, clinical findings and 90-day mortality. We analysed the baseline ECG of 196 patients who were included in a multinational prospective study of CS. The patients were divided into 3 groups: (a) ST-segment elevation (STE). (b) ST-segment depression (STDEP). (c) No ST-segment deviation or ST-segment impossible to analyse (NSTD). A subgroup analysis of the ACS patients was conducted. ST-segment deviations were present in 80% of the patients: 52% had STE and 29% had STDEP. STE was associated with the ACS aetiology, but one-fourth of the STDEP patients had aetiology other than ACS. The overall 90-day mortality was 41%: in STE 47%, STDEP 36% and NSTD 33%. In the multivariate mortality analysis, only STE predicted mortality (HR 1.74, CI 95 1.07-2.84). In the ACS subgroup, the patients were equally effectively revascularized, and no differences in the survival were noted between the study groups. ST-segment elevation is associated with the ACS aetiology and high mortality in the unselected CS population. If STE is not present, other aetiologies must be considered. When effectively revascularized, the prognosis is similar regardless of the ST-segment pattern in ACS-related CS. © 2018 Wiley Periodicals, Inc.

  1. Shock-induced transformations in crystalline RDX: a uniaxial constant-stress Hugoniostat molecular dynamics simulation study.

    Science.gov (United States)

    Bedrov, Dmitry; Hooper, Justin B; Smith, Grant D; Sewell, Thomas D

    2009-07-21

    Molecular dynamics (MD) simulations of uniaxial shock compression along the [100] and [001] directions in the alpha polymorph of hexahydro-1,3,5-trinitro-1,3,5-triazine (alpha-RDX) have been conducted over a wide range of shock pressures using the uniaxial constant stress Hugoniostat method [Ravelo et al., Phys. Rev. B 70, 014103 (2004)]. We demonstrate that the Hugoniostat method is suitable for studying shock compression in atomic-scale models of energetic materials without the necessity to consider the extremely large simulation cells required for an explicit shock wave simulation. Specifically, direct comparison of results obtained using the Hugoniostat approach to those reported by Thompson and co-workers [Phys. Rev. B 78, 014107 (2008)] based on large-scale MD simulations of shocks using the shock front absorbing boundary condition (SFABC) approach indicates that Hugoniostat simulations of systems containing several thousand molecules reproduced the salient features observed in the SFABC simulations involving roughly a quarter-million molecules, namely, nucleation and growth of nanoscale shear bands for shocks propagating along the [100] direction and the polymorphic alpha-gamma phase transition for shocks directed along the [001] direction. The Hugoniostat simulations yielded predictions of the Hugoniot elastic limit for the [100] shock direction consistent with SFABC simulation results.

  2. Scanning tunneling microscopy of monoatomic gold chains on vicinal Si(335) surface: experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Krawiec, M.; Kwapinski, T.; Jalochowski, M. [Institute of Physics and Nanotechnology Center, M. Curie-Sklodowska University, pl. M. Curie-Sklodowskiej 1, 20-031 Lublin (Poland)

    2005-02-01

    We study electronic and topographic properties of the Si(335) surface, containing Au wires parallel to the steps. We use scanning tunneling microscopy (STM) supplemented by reflection of high energy electron diffraction (RHEED) technique. The STM data show the space and voltage dependent oscillations of the distance between STM tip and the surface which can be explained within one band tight binding Hubbard model. We calculate the STM current using nonequilibrium Keldysh Green function formalism. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Experimental study of macroscopic quantum tunnelling in Bi2212 intrinsic Josephson junctions

    International Nuclear Information System (INIS)

    Matsumoto, Tetsuro; Kashiwaya, Hiromi; Shibata, Hajime; Kashiwaya, Satoshi; Kawabata, Shiro; Eisaki, Hiroshi; Yoshida, Yoshiyuki; Tanaka, Yukio

    2007-01-01

    The quantum dynamics of Bi 2 Sr 2 CaCu 2 O 8+δ intrinsic Josephson junctions (IJJs) is studied based on escape rate measurements. The saturations observed in the escape temperature and in the width of the switching current below 0.5 K (= T * ) indicate the transition of the switching mechanism from thermal activation to macroscopic quantum tunnelling. It is shown that the switching properties are consistently explained in terms of the underdamped Josephson junction with a quality factor of 70 ± 20 in spite of possible damping due to the nodal quasiparticles of d-wave superconductivity. The present result gives the upper limit of the damping of IJJs

  4. Study of particles clouds ejected under shock: the contributions of Photonic Doppler Velocimetry

    International Nuclear Information System (INIS)

    Prudhomme, Gabriel

    2014-01-01

    A metal plate subjected to a shock (tin, 10 GPa) undergoes a variety of damages such as spalling or the ejection of a cloud of particles. Two main mechanisms govern the formation of this cloud: the micro-jetting and the melting under shock. Photonic Doppler Velocimetry (PDV, a.k.a. LDV or het-V) is a multi-velocity time-resolved diagnostic. Developed from 2000's, the all-fibered conception makes its integration easy into shock experiments. The purpose of the thesis is to describe the contributions of PDV systems for high-velocity (several km/s) particle-cloud characterization, including micro-jetting cloud. This document presents a state of the art of shock generators, diagnostics and (numerical and experimental) studies involved in metallic micro-machined jetting. An extensive study of a PDV system is proposed. It leads to the definition of time-velocity spectrogram, evaluated in units of collected power, and a detection capability limit. Thanks to photon diffusion models, a threshold in the diameter of the measured particle is estimated. A PDV spectrogram simulation program is shown within the framework of particle clouds. Finally, several experimental campaigns are exposed. They emphasize the remarkable capacities of the system; results are compared to simulations. Diameter distributions are inferred using slowing down in air or in other gazes. Some radiometric analyses are also performed. (author) [fr

  5. Shock tube/time-of-flight mass spectrometer for high temperature kinetic studies

    International Nuclear Information System (INIS)

    Tranter, Robert S.; Giri, Binod R.; Kiefer, John H.

    2007-01-01

    A shock tube (ST) with online, time-of-flight mass spectrometric (TOF-MS) detection has been constructed for the study of elementary reactions at high temperature. The ST and TOF-MS are coupled by a differentially pumped molecular beam sampling interface, which ensures that the samples entering the TOF-MS are not contaminated by gases drawn from the cold end wall thermal boundary layer in the ST. Additionally, the interface allows a large range of postshock pressures to be used in the shock tube while maintaining high vacuum in the TOF-MS. The apparatus and the details of the sampling system are described along with an analysis in which cooling of the sampled gases and minimization of thermal boundary layer effects are discussed. The accuracy of kinetic measurements made with the apparatus has been tested by investigating the thermal unimolecular dissociation of cyclohexene to ethylene and 1,3-butadiene, a well characterized reaction for which considerable literature data that are in good agreement exist. The experiments were performed at nominal reflected shock wave pressures of 600 and 1300 Torr, and temperatures ranging from 1260 to 1430 K. The rate coefficients obtained are compared with the earlier shock tube studies and are found to be in very good agreement. As expected no significant difference is observed in the rate constant between pressures of 600 and 1300 Torr

  6. Adrenal gland volume measurement in septic shock and control patients: a pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Nougaret, Stephanie; Aufort, S.; Gallix, B. [Hopital Saint Eloi, Department of Abdominal Imaging, CHU Montpellier, Montpellier, Cedex 5 (France); Jung, B.; Chanques, G.; Jaber, S. [Hopital Saint Eloi, Intensive Care Unit, Department of Critical Care and Anesthesiology: DAR B, CHU Montpellier, Montpellier, Cedex 5 (France)

    2010-10-15

    To compare adrenal gland volume in septic shock patients and control patients by using semi-automated volumetry. Adrenal gland volume and its inter-observer variability were measured with tomodensitometry using semi-automated software in 104 septic shock patients and in 40 control patients. The volumes of control and septic shock patients were compared and the relationship between volume and outcome in intensive care was studied. The mean total volume of both adrenal glands was 7.2 {+-} 2.0 cm{sup 3} in control subjects and 13.3 {+-} 4.7 cm{sup 3} for total adrenal gland volume in septic shock patients (p < 0.0001). Measurement reproducibility was excellent with a concordance correlation coefficient value of 0.87. The increasing adrenal gland volume was associated with a higher rate of survival in intensive care. The present study reports that with semi-automated software, adrenal gland volume can be measured easily and reproducibly. Adrenal gland volume was found to be nearly double in sepsis compared with control patients. The absence of increased volume during sepsis would appear to be associated with a higher rate of mortality and may represent a prognosis factor which may help the clinician to guide their strategy. (orig.)

  7. Adrenal gland volume measurement in septic shock and control patients: a pilot study

    International Nuclear Information System (INIS)

    Nougaret, Stephanie; Aufort, S.; Gallix, B.; Jung, B.; Chanques, G.; Jaber, S.

    2010-01-01

    To compare adrenal gland volume in septic shock patients and control patients by using semi-automated volumetry. Adrenal gland volume and its inter-observer variability were measured with tomodensitometry using semi-automated software in 104 septic shock patients and in 40 control patients. The volumes of control and septic shock patients were compared and the relationship between volume and outcome in intensive care was studied. The mean total volume of both adrenal glands was 7.2 ± 2.0 cm 3 in control subjects and 13.3 ± 4.7 cm 3 for total adrenal gland volume in septic shock patients (p < 0.0001). Measurement reproducibility was excellent with a concordance correlation coefficient value of 0.87. The increasing adrenal gland volume was associated with a higher rate of survival in intensive care. The present study reports that with semi-automated software, adrenal gland volume can be measured easily and reproducibly. Adrenal gland volume was found to be nearly double in sepsis compared with control patients. The absence of increased volume during sepsis would appear to be associated with a higher rate of mortality and may represent a prognosis factor which may help the clinician to guide their strategy. (orig.)

  8. Work-related carpal tunnel syndrome treatment: a cross-sectional study among 106 patients

    Directory of Open Access Journals (Sweden)

    M. Aouatef

    2017-08-01

    Full Text Available The objective is to assess the influence of sociodemographic, professional and clinical variables on the choice of treatment of work-related carpal tunnel syndrome (CTS. An exhaustive and trans-sectional study was conducted over a period of eight years, from 1st January 2006 to 31 December 2013 in the Department of Occupational Medicine at University Hospital of Mahdia, Tunisia. The study population was represented by patients with work-related carpal tunnel syndrome. Data collection was based on a questionnaire sheet, describing social, occupational and medical characteristics of patients. The study population was characterized by a large female dominance, representing 95.3% with an average age of 42±7.8 years. Patients medically treated represented 38.7% and 61.3% had had surgical treatment. After binary logistic regression, surgical indication of CTS was significantly correlated to diabetes (p=0.017, other musculoskeletal disorders (p=0.02, functional signs of CTS (acrocyanosis p=0.05; muscle weakness p=0.015; radiating pain p=0.01; painful discomfort of the hand, the forearm or arm p=0.027 and to the atrophy of thenar muscles (p=0.018. According to this study, the choice of therapy for occupational CTS depends only on clinical data. More detailed studies will be needed to refine these results.

  9. Study of Unsteady, Sphere-Driven, Shock-Induced Combustion for Application to Hypervelocity Airbreathing Propulsion

    Science.gov (United States)

    Axdahl, Erik; Kumar, Ajay; Wilhite, Alan

    2011-01-01

    A premixed, shock-induced combustion engine has been proposed in the past as a viable option for operating in the Mach 10 to 15 range in a single stage to orbit vehicle. In this approach, a shock is used to initiate combustion in a premixed fuel/air mixture. Apparent advantages over a conventional scramjet engine include a shorter combustor that, in turn, results in reduced weight and heating loads. There are a number of technical challenges that must be understood and resolved for a practical system: premixing of fuel and air upstream of the combustor without premature combustion, understanding and control of instabilities of the shock-induced combustion front, ability to produce sufficient thrust, and the ability to operate over a range of Mach numbers. This study evaluated the stability of the shock-induced combustion front in a model problem of a sphere traveling in a fuel/air mixture at high Mach numbers. A new, rapid analysis method was developed and applied to study such flows. In this method the axisymmetric, body-centric Navier-Stokes equations were expanded about the stagnation streamline of a sphere using the local similarity hypothesis in order to reduce the axisymmetric equations to a quasi-1D set of equations. These reduced sets of equations were solved in the stagnation region for a number of flow conditions in a premixed, hydrogen/air mixture. Predictions from the quasi-1D analysis showed very similar stable or unstable behavior of the shock-induced combustion front as compared to experimental studies and higher-fidelity computational results. This rapid analysis tool could be used in parametric studies to investigate effects of fuel rich/lean mixtures, non-uniformity in mixing, contaminants in the mixture, and different chemistry models.

  10. Low-temperature magnetic study of naturally and experimentally shocked pyrrhotite

    Science.gov (United States)

    Mang, C.; Kontny, A. M.; Hecht, L.

    2011-12-01

    the LT in-phase and out-of-phase susceptibility measurements hard to interpret. A general feature with increasing shock pressure, however, is a broadening of the temperature interval where transition temperatures occur, as well in the LT remanence and HT susceptibility curves. In the remanence curves of the experimentally shocked samples this behaviour is accompanied by an earlier onset of the 30 K transition. The transition is only visible as a slight bending in the susceptibility curves and with increasing shock pressure this bending disappears continuously and is no longer visible at 8 GPa. Samples shocked above 8 GPa also show a slightly stronger frequency dependency of AC suceptibility. Further TEM studies will show if these observations might give some clues on the lattice defect concentration of pyrrhotite and can be used as shock indicators. Rochette, P.et al., 1990. Earth Planet. Sci. Lett., 98, 319 - 328. Wittmann, A. et al., 2009, Geol. Soc. Am. Spec. Pap. 458, 377 - 396

  11. Experimental studies of collisional plasma shocks and plasma interpenetration via merging supersonic plasma jets

    Science.gov (United States)

    Hsu, S. C.; Moser, A. L.; Merritt, E. C.; Adams, C. S.

    2015-11-01

    Over the past 4 years on the Plasma Liner Experiment (PLX) at LANL, we have studied obliquely and head-on-merging supersonic plasma jets of an argon/impurity or hydrogen/impurity mixture. The jets are formed/launched by pulsed-power-driven railguns. In successive experimental campaigns, we characterized the (a) evolution of plasma parameters of a single plasma jet as it propagated up to ~ 1 m away from the railgun nozzle, (b) density profiles and 2D morphology of the stagnation layer and oblique shocks that formed between obliquely merging jets, and (c) collisionless interpenetration transitioning to collisional stagnation between head-on-merging jets. Key plasma diagnostics included a fast-framing CCD camera, an 8-chord visible interferometer, a survey spectrometer, and a photodiode array. This talk summarizes the primary results mentioned above, and highlights analyses of inferred post-shock temperatures based on observations of density gradients that we attribute to shock-layer thickness. We also briefly describe more recent PLX experiments on Rayleigh-Taylor-instability evolution with magnetic and viscous effects, and potential future collisionless shock experiments enabled by low-impurity, higher-velocity plasma jets formed by contoured-gap coaxial guns. Supported by DOE Fusion Energy Sciences and LANL LDRD.

  12. Simultaneous X-ray imaging and diffraction study of shock propagation and phase transition in silicon

    Science.gov (United States)

    Galtier, Eric

    2017-06-01

    X-ray phase contrast imaging technique using a free electron laser have observed the propagation of laser-driven shock waves directly inside materials. While providing images with few hundred nanometers spatial resolution, access to more quantitative information like the material density and the various shock front speeds remain challenging due to imperfections in the images limiting the convergence in the reconstruction algorithm. Alternatively, pump-probe X-ray diffraction (XRD) is a robust technique to extract atomic crystalline structure of compressed matter, providing insight into the kinetics of phase transformation and material response to stress. However, XRD by itself is not sufficient to extract the equation of state of the material under study. Here we report on the use of the LCLS free electron laser as a source of a high-resolution X-ray microscopy enabling the direct imaging of shock waves and phase transitions in optically opaque silicon. In this configuration, no algorithm is necessary to extract the material density and the position of the shock fronts. Simultaneously, we probed the crystalline structure via XRD of the various phases in laser compressed silicon. E. Galtier, B. Nagler, H. J. Lee, S. Brown, E. Granados, A. Hashim, E. McBride, A. Mackinnon, I. Nam, J. Zimmerman (SLAC) A. Gleason (Stanford, LANL) A. Higginbotham (University of York) A. Schropp, F. Seiboth (DESY).

  13. A High-Purity Alumina for Use in Studies of Shock Loaded Samples

    Science.gov (United States)

    Lacina, David; Neel, Christopher

    2017-06-01

    We report the results of plate impact experiments on a potential new ``standard'' material, Coorstek Plasmapure-UC (99.9% purity) polycrystalline alumina, for use in non-conduction, impact environment, shock loading studies. This work was motivated by a desire to find a 99.9% purity alumina to replace the now unavailable Coors Vistal (99.9%) alumina, as it was hoped the Hugoniot elastic limit (HEL) of the new standard would match the 9-11 GPa value of Vistal. Shock response data, including the HEL, Hugoniot particle velocities, Hugoniot shock velocities, stress vs volume, and release wave speeds, was obtained up to 14 GPa. This data will be compared with Hugoniot curve data for other high purity alumina to contrast differences in the shock response, and is intended to be useful in impedance matching calculations. We will show that the HEL of Plasmapure-UC alumina is 5.5 GPa and speculate on causes for this lower than expected value. We will also explore why the elastic-plastic response for Plasmapure-UC alumina differs from what has been observed from other high purity alumina. The final result of this work is to recommend a well-characterized, lower purity alumina (Coorstek AD-995) as a potential new ``standard'' material.

  14. The effects of area contraction on the performance of UNITEN's shock tube: Numerical study

    International Nuclear Information System (INIS)

    Mohsen, A M; Yusoff, M Z; Al-Falahi, A

    2013-01-01

    Numerical study into the effects of area contraction on shock tube performance has been reported in this paper. The shock tube is an important component of high speed fluid flow test facility was designed and built at the Universiti Tenaga Nasional (UNITEN). In the above mentioned facility, a small area contraction, in form of a bush, was placed adjacent to the diaphragm section to facilitate the diaphragm rupturing process when the pressure ratio across the diaphragm increases to a certain value. To investigate the effects of the small area contraction on facility performance, numerical simulations were conducted at different operating conditions (diaphragm pressure ratios P 4 /P 1 of 10, 15, and 20). A two-dimensional time-accurate Navier-Stokes CFD solver was used to simulate the transient flow in the facility with and without area contraction. The numerical results show that the facility performance is influenced by area contraction in the diaphragm section. For instance, when operating the facility with area contraction using diaphragm pressure ratio (P 4 /P 1 ) of 10, the shock wave strength and shock wave speed decrease by 18% and 8% respectively.

  15. Parametric study of flow patterns behind the standing accretion shock wave for core-collapse supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Iwakami, Wakana; Nagakura, Hiroki [Yukawa Institute for Theoretical Physics, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan); Yamada, Shoichi, E-mail: wakana@heap.phys.waseda.ac.jp [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555 (Japan)

    2014-05-10

    In this study, we conduct three-dimensional hydrodynamic simulations systematically to investigate the flow patterns behind the accretion shock waves that are commonly formed in the post-bounce phase of core-collapse supernovae. Adding small perturbations to spherically symmetric, steady, shocked accretion flows, we compute the subsequent evolutions to find what flow pattern emerges as a consequence of hydrodynamical instabilities such as convection and standing accretion shock instability for different neutrino luminosities and mass accretion rates. Depending on these two controlling parameters, various flow patterns are indeed realized. We classify them into three basic patterns and two intermediate ones; the former includes sloshing motion (SL), spiral motion (SP), and multiple buoyant bubble formation (BB); the latter consists of spiral motion with buoyant-bubble formation (SPB) and spiral motion with pulsationally changing rotational velocities (SPP). Although the post-shock flow is highly chaotic, there is a clear trend in the pattern realization. The sloshing and spiral motions tend to be dominant for high accretion rates and low neutrino luminosities, and multiple buoyant bubbles prevail for low accretion rates and high neutrino luminosities. It is interesting that the dominant pattern is not always identical between the semi-nonlinear and nonlinear phases near the critical luminosity; the intermediate cases are realized in the latter case. Running several simulations with different random perturbations, we confirm that the realization of flow pattern is robust in most cases.

  16. THE IMPACT OF ANXIETY UPON COGNITION: PERSPECTIVES FROM HUMAN THREAT OF SHOCK STUDIES

    Directory of Open Access Journals (Sweden)

    Oliver Joe Robinson

    2013-05-01

    Full Text Available Anxiety disorders constitute a sizeable worldwide health burden with profound social and economic consequences. The symptoms are wide-ranging; from hyperarousal to difficulties with concentrating. This latter effect falls under the broad category of altered cognitive performance; in this review we examine studies quantifying such impacts of anxiety on cognition. Specifically, we focus on the translational threat of unpredictable shock paradigm, a method previously used to characterize emotional responses and defensive mechanisms that is now emerging as valuable tool for examining the interaction between anxiety and cognition. In particular, we compare the impact of threat of shock on cognition in humans to that of pathological anxiety disorders. We highlight that both threat of shock and anxiety disorders promote mechanisms associated with harm avoidance across multiple levels of cognition (from perception to attention to learning and executive function – a ‘hot’ cognitive function which can be both adaptive and maladaptive depending upon the circumstances. This mechanism comes at a cost to other functions such as working memory, but leaves some functions, such as planning, unperturbed. We also highlight a number of cognitive effects that differ across anxiety disorders and threat of shock. These discrepant effects are largely seen in ‘cold’ cognitive functions involving control mechanisms and may reveal boundaries between adaptive (e.g. response to threat and maladaptive (e.g. pathological anxiety. We conclude by raising a number of unresolved questions regarding the role of anxiety in cognition that may provide fruitful avenues for future research.

  17. Basic study on promotion of thawing frozen soil by shock loading

    Directory of Open Access Journals (Sweden)

    Toshiaki WATANABE

    2008-06-01

    Full Text Available The aim of study is to confirm a new technique that can crush the frozen soil and/or ice block using underwater shock wave generated by the underwater explosion of explosive. This technique can lead to the earlier sowing, which can have the larger harvest because the duration of sunshine increases. Especially, in Hokkaido prefecture, Japan, if the sowing is carried out in April, we can expect to have 150% of harvest in the ordinary season. In the case of small processing area such as road repairing, frozen soil is thawed by using the heat of gas burner and/or the electric heater. It is not a suitable plan to apply these heating methods to agriculture, from the point of view enormous amount of processing area. Thawing technique for frozen soil is effective against the cold regions, for example, Russia, Norway, and Sweden, etc. At first, we carried out experiments using a detonating fuse and ice block. The propagation process of shock wave into the ice block was observed by means of a high-speed camera. In order to check about that influence we tried to give an actual frozen soil a shock wave. We could get a result that existence of water layer serves an important role in promotion of thawing by the shock loading to the frozen soil.

  18. Shock wave generation in laser ablation studied using pulsed digital holographic interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Amer, Eynas; Gren, Per; Sjoedahl, Mikael [Division of Experimental Mechanics, Luleaa University of Technology, SE-971 87 Luleaa (Sweden)], E-mail: eynas.amer@ltu.se, E-mail: per.gren@ltu.se, E-mail: mikael.sjodahl@ltu.se

    2008-11-07

    Pulsed digital holographic interferometry has been used to study the shock wave induced by a Q-switched Nd-YAG laser ({lambda} = 1064 nm and pulse duration 12 ns) on a polycrystalline boron nitride (PCBN) ceramic target under atmospheric air pressure. A special setup based on using two synchronized wavelengths from the same laser for processing and measurement simultaneously has been introduced. Collimated laser light ({lambda} = 532 nm) passed through the volume along the target and digital holograms were recorded for different time delays after processing starts. Numerical data of the integrated refractive index field were calculated and presented as phase maps showing the propagation of the shock wave generated by the process. The location of the induced shock wave front was observed for different focusing and time delays. The amount of released energy, i.e. the part of the incident energy of the laser pulse that is eventually converted to a shock wave has been estimated using the point explosion model. The released energy is normalized by the incident laser pulse energy and the energy conversion efficiency between the laser pulse and PCBN target has been calculated at different power densities. The results show that the energy conversion efficiency seems to be constant around 80% at high power densities.

  19. Experimental and numerical study of the micro-spalling of metallic targets subjected to laser shock

    International Nuclear Information System (INIS)

    Loison, D.

    2012-01-01

    Micro-spalling is a failure phenomenon consisting in dynamic fragmentation of a material after partial or full melting under intense shock wave loading. High power pulsed lasers are used as shock wave generators in laboratory for scientific and industrial purposes, such as research on inertial confinement fusion. In this context, the production of high velocity fragments can damage the facilities where shock experiments are conducted. This thesis, realized in collaboration with different teams from CEA, aims at understanding and modeling the different processes involved in micro-spalling phenomenon. Experiments to study micro-spalling of laser shock-loaded tin and aluminum targets have been performed. Various and complementary diagnostics (photonic Doppler velocimetry, soft recovery of debris and microtomography) have been used to characterize the ballistic properties (size distributions and velocities) of droplets constituting the micro-spalling cloud. In parallel, phase transition and fragmentation models have been adapted to simulate micro-spalling. These models have been implemented in a code to predict the sizes and velocities of debris. The combination of experimental and numerical results allows characterizing the successive stages of micro-spalling from laser-matter interaction to the ejection of droplets. (author)

  20. Studies of renal parenchymal impairments with extracorporeal shock wave lithotripsy (ESWL) by diagnostic imaging methods

    Energy Technology Data Exchange (ETDEWEB)

    Ohishi, Yukihiko; Machida, Toyohei; Tashiro, Kazuya; Wada, Tetsuro; Mochizuki, Atsushi; Torii, Shinichiro; Yoshigoe, Fukuo; Kawashima, Yoshio; Asano, Koji (Jikei Univ., Tokyo (Japan). School of Medicine)

    1989-05-01

    Renal parenchymal impairments with extracorporeal shock wave lithotripsy (ESWL) were studied by diagnostic imaging methods. The subjects were 25 patients with renal stones, and EDAP LT-01 (piezoelectric system) was used for the equipment of ESWL. The examination by MRI, X-ray CT and /sup 99m/Tc-DMSA scintigraphy using SPECT were performed before and after ESWL. To the 24 kidneys of 12 adult dogs, shock waves were fired in order to examine the experimental renal parenchymal impairments. After the treatment with ESWL, renal abnormal findings were obtained with MRI in 6 patients out of 11 (54.5%), with X-ray CT in 1 patient out of 12 (8.3%), and with the /sup 99m/Tc-DMSA renal scintigraphy in 4 patients out of 6 (66.7%). In the inspections with X-ray CT and renal scintigraphy conducted in 4 weeks, it was noted that the conditions of patients were recovered to the states before ESWL was performed. Using the therapeutic doses of shock wave for humans, the renal parenchymal impairments in the kidney in dogs were normalized in 7 days. Although it has been considered that the degree of renal parenchymal impairments with ESWL treatment may be influenced by the kind of the equipment, frequency of shock waves and their strength, the extent of impairments were rather mild, and it was presumed that the impairments might be recovered on the images in 3 to 4 weeks at the latest. (author).

  1. Studies of renal parenchymal impairments with extracorporeal shock wave lithotripsy (ESWL) by diagnostic imaging methods

    International Nuclear Information System (INIS)

    Ohishi, Yukihiko; Machida, Toyohei; Tashiro, Kazuya; Wada, Tetsuro; Mochizuki, Atsushi; Torii, Shinichiro; Yoshigoe, Fukuo; Kawashima, Yoshio; Asano, Koji

    1989-01-01

    Renal parenchymal impairments with extracorporeal shock wave lithotripsy (ESWL) were studied by diagnostic imaging methods. The subjects were 25 patients with renal stones, and EDAP LT-01 (piezoelectric system) was used for the equipment of ESWL. The examination by MRI, X-ray CT and 99m Tc-DMSA scintigraphy using SPECT were performed before and after ESWL. To the 24 kidneys of 12 adult dogs, shock waves were fired in order to examine the experimental renal parenchymal impairments. After the treatment with ESWL, renal abnormal findings were obtained with MRI in 6 patients out of 11 (54.5%), with X-ray CT in 1 patient out of 12 (8.3%), and with the 99m Tc-DMSA renal scintigraphy in 4 patients out of 6 (66.7%). In the inspections with X-ray CT and renal scintigraphy conducted in 4 weeks, it was noted that the conditions of patients were recovered to the states before ESWL was performed. Using the therapeutic doses of shock wave for humans, the renal parenchymal impairments in the kidney in dogs were normalized in 7 days. Although it has been considered that the degree of renal parenchymal impairments with ESWL treatment may be influenced by the kind of the equipment, frequency of shock waves and their strength, the extent of impairments were rather mild, and it was presumed that the impairments might be recovered on the images in 3 to 4 weeks at the latest. (author)

  2. Knee rotation influences the femoral tunnel angle measurement after anterior cruciate ligament reconstruction: a 3-dimensional computed tomography model study

    Science.gov (United States)

    Tang, Jing; Thorhauer, Eric; Marsh, Chelsea; Fu, Freddie H.

    2013-01-01

    Purpose Femoral tunnel angle (FTA) has been proposed as a metric for evaluating whether ACL reconstruction was performed anatomically. In clinic, radiographic images are typically acquired with an uncertain amount of internal/external knee rotation. The extent to which knee rotation will influence FTA measurement is unclear. Furthermore, differences in FTA measurement between the two common positions (0° and 45° knee flexion) have not been established. The purpose of this study was to investigate the influence of knee rotation on FTA measurement after ACL reconstruction. Methods Knee CT data from 16 subjects were segmented to produce 3D bone models. Central axes of tunnels were identified. The 0° and 45° flexion angles were simulated. Knee internal/external rotations were simulated in a range of ±20°. FTA was defined as the angle between the tunnel axis and femoral shaft axis, orthogonally projected into the coronal plane. Results Femoral tunnel angle was positively/negatively correlated with knee rotation angle at 0°/45° knee flexion. At 0° knee flexion, FTA for anterio-medial (AM) tunnels was significantly decreased at 20° of external knee rotation. At 45° knee flexion, more than 16° external or 19° internal rotation significantly altered FTA measurements for single-bundle tunnels; smaller rotations (±9° for AM, ±5° for PL) created significant errors in FTA measurements after double-bundle reconstruction. Conclusion Femoral tunnel angle measurements were correlated with knee rotation. Relatively small imaging malalignment introduced significant errors with knee flexed 45°. This study supports using the 0° flexion position for knee radiographs to reduce errors in FTA measurement due to knee internal/external rotation. Level of evidence Case–control study, Level III. PMID:23589127

  3. Increased Risk of New-Onset Hypertension After Shock Wave Lithotripsy in Urolithiasis: A Nationwide Cohort Study.

    Science.gov (United States)

    Huang, Shi-Wei; Tsai, Chung-You; Wang, Jui; Pu, Yeong-Shiau; Chen, Pei-Chun; Huang, Chao-Yuan; Chien, Kuo-Liong

    2017-10-01

    Although shock wave lithotripsy is minimally invasive, earlier studies argued that it may increase patients' subsequent risk of hypertension and diabetes mellitus. This study evaluated the association between shock wave lithotripsy and new-onset hypertension or diabetes mellitus. The Taiwanese National Health Insurance Research Database was used to identify 20 219 patients aged 18 to 65 years who underwent the first stone surgical treatment (shock wave lithotripsy or ureterorenoscopic lithotripsy) between January 1999 and December 2011. A Cox proportional model was applied to evaluate associations. Time-varying Cox models were applied to evaluate the association between the number of shock wave lithotripsy sessions and the incidence of hypertension or diabetes mellitus. After a median follow-up of 74.9 and 82.6 months, 2028 and 688 patients developed hypertension in the shock wave lithotripsy and ureterorenoscopic lithotripsy groups, respectively. Patients who underwent shock wave lithotripsy had a higher probability of developing hypertension than patients who underwent ureterorenoscopic lithotripsy, with a hazard ratio of 1.20 (95% confidence interval, 1.10-1.31) after adjusting for covariates. The risk increased as the number of shock wave lithotripsy sessions increased. However, the diabetes mellitus risk was similar in the shock wave lithotripsy and ureterorenoscopic lithotripsy groups. Furthermore, the hazard ratio did not increase as the number of shock wave lithotripsy sessions increased. Shock wave lithotripsy consistently increased the incidence of hypertension on long-term follow-up. Therefore, alternatives to urolithiasis treatment (eg, endoscopic surgery or medical expulsion therapy) could avoid the hypertension risk. Furthermore, avoiding multiple sessions of shock wave lithotripsy could also evade the hypertension risk. © 2017 American Heart Association, Inc.

  4. Sonographic diagnosis of carpal tunnel syndrome: a study in 200 hospital workers

    Directory of Open Access Journals (Sweden)

    Adham do Amaral e Castro

    2015-10-01

    Full Text Available AbstractObjective:To describe the prevalence of carpal tunnel syndrome in a sample of 200 healthy hospital workers, establishing the respective epidemiological associations.Materials and Methods:Two hundred individuals were submitted to wrist ultrasonography to measure the median nerve area. They were questioned and examined for epidemiological data, body mass index, carpal tunnel syndrome signs and symptoms, and submitted to the Boston carpal tunnel questionnaire (BCTQ to evaluate the carpal tunnel syndrome severity. A median nerve area ≥ 9 mm2 was considered to be diagnostic of carpal tunnel syndrome.Results:Carpal tunnel syndrome was diagnosed by ultrasonography in 34% of the sample. It was observed the association of carpal tunnel syndrome with age (p < 0.0001, paresthesia (p < 0.0001, Tinel's test (p < 0.0001, Phalen's test (p< 0.0001, BCTQ score (p < 0.0001, and years of formal education (p < 0.0001. Years of formal education was the only variable identified as an independent risk factor for carpal tunnel syndrome (95% CI = 1.03 to 1.24.Conclusion:The prevalence of carpal tunnel syndrome in a population of hospital workers was of 34%. The number of years of formal education was the only independent risk factor for carpal tunnel syndrome.

  5. A vegetation modeling concept for Building and Environmental Aerodynamics wind tunnel tests and its application in pollutant dispersion studies

    International Nuclear Information System (INIS)

    Gromke, Christof

    2011-01-01

    A new vegetation modeling concept for Building and Environmental Aerodynamics wind tunnel investigations was developed. The modeling concept is based on fluid dynamical similarity aspects and allows the small-scale modeling of various kinds of vegetation, e.g. field crops, shrubs, hedges, single trees and forest stands. The applicability of the modeling concept was validated in wind tunnel pollutant dispersion studies. Avenue trees in urban street canyons were modeled and their implications on traffic pollutant dispersion were investigated. The dispersion experiments proved the modeling concept to be practicable for wind tunnel studies and suggested to provide reliable concentration results. Unfavorable effects of trees on pollutant dispersion and natural ventilation in street canyons were revealed. Increased traffic pollutant concentrations were found in comparison to the tree-free reference case. - Highlights: → A concept for aerodynamic modelling of vegetation in small scale wind tunnel studies is presented. → The concept was applied to study pollutant dispersion in urban street canyons with avenue tress. → The wind tunnel studies show that modelling the aerodynamic effects of vegetation is important. → Avenue trees give rise to increased pollutant concentrations in urban street canyons. - Avenue trees in urban street canyons affect the pollutant dispersion and result in increased traffic exhaust concentrations.

  6. Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities

    Science.gov (United States)

    Jung, Han Sae; Tsai, Hsin-Zon; Wong, Dillon; Germany, Chad; Kahn, Salman; Kim, Youngkyou; Aikawa, Andrew S.; Desai, Dhruv K.; Rodgers, Griffin F.; Bradley, Aaron J.; Velasco, Jairo; Watanabe, Kenji; Taniguchi, Takashi; Wang, Feng; Zettl, Alex; Crommie, Michael F.

    2015-01-01

    Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees of freedom to control electronic devices. In particular, the behavior of graphene’s charge carriers in response to potentials from charged Coulomb impurities is predicted to differ significantly from that of most materials. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) can provide detailed information on both the spatial and energy dependence of graphene's electronic structure in the presence of a charged impurity. The design of a hybrid impurity-graphene device, fabricated using controlled deposition of impurities onto a back-gated graphene surface, has enabled several novel methods for controllably tuning graphene’s electronic properties.1-8 Electrostatic gating enables control of the charge carrier density in graphene and the ability to reversibly tune the charge2 and/or molecular5 states of an impurity. This paper outlines the process of fabricating a gate-tunable graphene device decorated with individual Coulomb impurities for combined STM/STS studies.2-5 These studies provide valuable insights into the underlying physics, as well as signposts for designing hybrid graphene devices. PMID:26273961

  7. Scanning Tunnelling Spectroscopic Studies of Dirac Fermions in Graphene and Topological Insulators

    Directory of Open Access Journals (Sweden)

    wang K.-L.

    2012-03-01

    Full Text Available We report novel properties derived from scanning tunnelling spectroscopic (STS studies of Dirac fermions in graphene and the surface state (SS of a strong topological insulator (STI, Bi2Se3. For mono-layer graphene grown on Cu by chemical vapour deposition (CVD, strain-induced scalar and gauge potentials are manifested by the charging effects and the tunnelling conductance peaks at quantized energies, respectively. Additionally, spontaneous time-reversal symmetry breaking is evidenced by the alternating anti-localization and localization spectra associated with the zero-mode of two sublattices while global time-reversal symmetry is preserved under the presence of pseudo-magnetic fields. For Bi2Se3 epitaxial films grown on Si(111 by molecular beam epitaxy (MBE, spatially localized unitary impurity resonances with sensitive dependence on the energy difference between the Fermi level and the Dirac point are observed for samples thicker than 6 quintuple layers (QL. These findings are characteristic of the SS of a STI and are direct manifestation of strong topological protection against impurities. For samples thinner than 6-QL, STS studies reveal the openup of an energy gap in the SS due to overlaps of wave functions between the surface and interface layers. Additionally, spin-preserving quasiparticle interference wave-vectors are observed, which are consistent with the Rashba-like spin-orbit splitting.

  8. RAM analysis of earth pressure balance tunnel boring machines: A case study

    Directory of Open Access Journals (Sweden)

    Hasel Amini Khoshalan

    2015-12-01

    Full Text Available Earth pressure balance tunnel boring machines (EPB-TBMs are favorably applied in urban tunneling projects. Despite their numerous advantages, considerable delays and high maintenance cost are the main disadvantages these machines suffer from. Reliability, availability, and maintainability (RAM analysis is a practical technique that uses failure and repair dataset obtained over a reasonable time for dealing with proper machine operation, maintenance scheduling, cost control, and improving the availability and performance of such machines. In the present study, a database of failures and repairs of an EBP-TBM was collected in line 1 of Tabriz subway project over a 26-month interval of machine operation. In order to model the reliability of the TBM, this machine was divided into five distinct subsystems including mechanical, electrical, hydraulic, pneumatic, and water systems in a series configuration. According to trend and serial correlation tests, the renewal processes were applied, for analysis of all subsystems. After calculating the reliability and maintainability functions for all subsystems, it was revealed that the mechanical subsystem with the highest failure frequency has the lowest reliability and maintainability. Similarly, estimating the availability of all subsystems indicated that the mechanical subsystem has a relatively low availability level of 52.6%, while other subsystems have acceptable availability level of 97%. Finally, the overall availability of studied machine was calculated as 48.3%.

  9. Focused and Radial Shock Wave Therapy in the Treatment of Tennis Elbow: A Pilot Randomised Controlled Study

    Directory of Open Access Journals (Sweden)

    Król Piotr

    2015-09-01

    Full Text Available The purpose of this article was to evaluate and compare the efficacy of radial and focused shock wave therapies applied to treat tennis elbow. Patients with tennis elbow were randomized into two comparative groups: focused shock wave therapy (FSWT; n=25 and radial shock wave therapy (RSWT; n=25. Subjects in the FSWT and RSWT groups were applied with a focused shock wave (3 sessions, 2000 shocks, 4 Hz, 0.2 mJ/mm2 and a radial shock wave (3 sessions, 2000 + 2000 shocks, 8 Hz, 2.5 bar, respectively. The primary study endpoints were pain relief and functional improvement (muscle strength one week after therapy. The secondary endpoint consisted of the results of the follow-up observation (3, 6 and 12 weeks after the study. Successive measurements showed that the amount of pain patients felt decreased in both groups. At the same time grip strength as well as strength of wrist extensors and flexors of the affected extremity improved significantly. Both focused and radial shock wave therapies can comparably and gradually reduce pain in subjects with tennis elbow. This process is accompanied by steadily improved strength of the affected extremity.

  10. Study on the snow drifting modelling criteria in boundary layer wind tunnels

    Directory of Open Access Journals (Sweden)

    Georgeta BĂETU

    2014-07-01

    Full Text Available The paper presents a study on modelling the wind drifting of the snow deposited on the flat roofs of buildings in wind tunnel. The physical model of snow drifting in wind tunnel simulating the urban exposure to wind action is not frequently reported in literature, but is justified by the serious damages under accidental important snow falls combined with strong wind actions on the roofs of various buildings. A uniform layer of snow deposited on the flat roof was exposed to wind action in order to obtain the drifting. The parameters involved in the modelling at reduced scale, with particles of glass beads, of the phenomenon of transportation of the snow from the roof were analysed, particularly the roughness length and the friction wind speed. A numerical simulation in ANSYS CFX program was developed in parallel, by which a more accurate visualization of the particularities of the wind flow over the roof was possible, in the specific areas where the phenomenon of snow transportation was more susceptible to occur. Modified roughness length and friction wind speed were determined through methods used in the literature, an attempt being made in this work to analyse the factors that influence their values.

  11. Wind tunnel study of natural ventilation of building integrated photovoltaics double skin façade

    Directory of Open Access Journals (Sweden)

    Hudişteanu Sebastian Valeriu

    2018-01-01

    Full Text Available The paper presents a wind tunnel experimental analysis of a small-scale building model (1:30. The objective of the study is to determine the wind influence on the ventilation of a double skin façade channel (DSF and the cooling effect over integrated photovoltaic panels. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The effect of the wind over the ventilation of the horizontal channels of double skin façades is evaluated for different incident velocities. The results are generalized for the average steady state values of the velocities analysed. The experimental results put in evidence the correlation between the reference wind velocity and the dynamics of the air movement inside the double skin façade. These values are used to determine the convective heat transfer and the cooling effect of the air streams inside the channel upon the integrated photovoltaic panels. The decrease of the photovoltaic panels temperature determines a raise of 11% in efficiency and power generated.

  12. A tunnelling study on polymer/1T-LixTaS2 layered nanocomposites

    International Nuclear Information System (INIS)

    Enomoto, Hiroyuki; Takai, Hiroyuki; Ozaki, Hajime; Lerner, Michael M

    2004-01-01

    Electronic structures near the Fermi level of polymer/1T-Li x TaS 2 layered nanocomposites have been studied by tunnelling spectroscopy. Polymer/1T-Li x TaS 2 layered nanocomposites were synthesized by using the exfoliation-adsorption technique. Single crystals of 1T-TaS 2 were used as host materials. Poly(ethylene oxide) (PEO) and poly(ethylenimine) (PEI) with different molecular weights were adopted as guest intercalants. Powder x-ray diffraction patterns showed that all samples of the polymer/1T-Li x TaS 2 layered nanocomposites contain organic polymer between all individual 1T-TaS 2 sheets. Although 1T-TaS 2 single crystal is well known to show quite unique temperature dependences of the resistivity due to the charge density wave (CDW), the resistivities of all polymer/1T-Li x TaS 2 nanocomposites showed semiconductor-like temperature dependences. The tunnelling spectra of polymer/1T-Li x TaS 2 nanocomposites revealed that the CDW gap disappears in the density of states near the Fermi level of polymer/1T-Li x TaS 2 nanocomposites and their electronic structures show a metallic behaviour

  13. Wind tunnel study of natural ventilation of building integrated photovoltaics double skin façade

    Science.gov (United States)

    Hudişteanu, Sebastian Valeriu; Popovici, Cătălin George; Cherecheş, Nelu-Cristian

    2018-02-01

    The paper presents a wind tunnel experimental analysis of a small-scale building model (1:30). The objective of the study is to determine the wind influence on the ventilation of a double skin façade channel (DSF) and the cooling effect over integrated photovoltaic panels. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The effect of the wind over the ventilation of the horizontal channels of double skin façades is evaluated for different incident velocities. The results are generalized for the average steady state values of the velocities analysed. The experimental results put in evidence the correlation between the reference wind velocity and the dynamics of the air movement inside the double skin façade. These values are used to determine the convective heat transfer and the cooling effect of the air streams inside the channel upon the integrated photovoltaic panels. The decrease of the photovoltaic panels temperature determines a raise of 11% in efficiency and power generated.

  14. Shock wave, fluid instability and implosion studies with a kinetic particle approach

    Science.gov (United States)

    Sagert, Irina; Even, Wesley P.; Strother, Terrance T.

    2016-10-01

    Many problems in laboratory plasma physics are subject to flows that move between the continuum and the kinetic regime. The correct description of these flows is crucial in order to capture their impact on the system's dynamical evolution. Examples are capsule implosions in inertial confinement fusion (ICF). Although their dynamics is predominantly shaped by shock waves and fluid instabilities, non-equilibrium flows in form of deuterium/tritium ions have been shown to play a significant role. We present recent studies with our Monte Carlo kinetic particle code that is designed to capture continuum and kinetic flows in large physical systems with possible applications in ICF studies. Discussed results will include standard shock wave and fluid instability tests and simulations that are adapted towards future ICF studies with comparisons to hydrodynamic simulations. This work used the Wolf TriLAB Capacity Cluster at LANL. I.S. acknowledges support through a Director's fellowship (20150741PRD3) from Los Alamos National Laboratory.

  15. Experimental Study of Fillets to Reduce Corner Effects in an Oblique Shock-Wave/Boundary Layer Interaction

    Science.gov (United States)

    Hirt, Stefanie M.

    2015-01-01

    A test was conducted in the 15 cm x 15 cm supersonic wind tunnel at NASA Glenn Research Center that focused on corner effects of an oblique shock-wave/boundary-layer interaction. In an attempt to control the interaction in the corner region, eight corner fillet configurations were tested. Three parameters were considered for the fillet configurations: the radius, the fillet length, and the taper length from the square corner to the fillet radius. Fillets effectively reduced the boundary-layer thickness in the corner; however, there was an associated penalty in the form of increased boundary-layer thickness at the tunnel centerline. Larger fillet radii caused greater reductions in boundary-layer thickness along the corner bisector. To a lesser, but measureable, extent, shorter fillet lengths resulted in thinner corner boundary layers. Overall, of the configurations tested, the largest radius resulted in the best combination of control in the corner, evidenced by a reduction in boundary-layer thickness, coupled with minimal impacts at the tunnel centerline.

  16. Albumin in Burn Shock Resuscitation: A Meta-Analysis of Controlled Clinical Studies.

    Science.gov (United States)

    Navickis, Roberta J; Greenhalgh, David G; Wilkes, Mahlon M

    2016-01-01

    Critical appraisal of outcomes after burn shock resuscitation with albumin has previously been restricted to small relatively old randomized trials, some with high risk of bias. Extensive recent data from nonrandomized studies assessing the use of albumin can potentially reduce bias and add precision. The objective of this meta-analysis was to determine the effect of burn shock resuscitation with albumin on mortality and morbidity in adult patients. Randomized and nonrandomized controlled clinical studies evaluating mortality and morbidity in adult patients receiving albumin for burn shock resuscitation were identified by multiple methods, including computer database searches and examination of journal contents and reference lists. Extracted data were quantitatively combined by random-effects meta-analysis. Four randomized and four nonrandomized studies with 688 total adult patients were included. Treatment effects did not differ significantly between the included randomized and nonrandomized studies. Albumin infusion during the first 24 hours showed no significant overall effect on mortality. However, significant statistical heterogeneity was present, which could be abolished by excluding two studies at high risk of bias. After those exclusions, albumin infusion was associated with reduced mortality. The pooled odds ratio was 0.34 with a 95% confidence interval of 0.19 to 0.58 (P Albumin administration was also accompanied by decreased occurrence of compartment syndrome (pooled odds ratio, 0.19; 95% confidence interval, 0.07-0.50; P albumin can improve outcomes of burn shock resuscitation. However, the scope and quality of current evidence are limited, and additional trials are needed.

  17. Theoretical, numerical and experimental study of accretion shocks dynamics in magnetic cataclysmic variables

    International Nuclear Information System (INIS)

    Busschaert, Clotilde

    2013-01-01

    Magnetic cataclysmic variables are interacting binary Systems containing a highly magnetized white dwarf which accretes material from a companion. Material is led along magnetic field lines and falls onto the magnetic pole(s) supersonically forming an accretion column. As the material hits the surface, a reverse shock is formed and the shocked region is structured by the cooling effect of radiation processes. This work is a multidisciplinary study of the dynamics of the accretion column. Firstly, a numerical study of the accretion column structure at the astrophysical scale is presented. The observational consequences are discussed. This approach is completed by experiments using radiative flows generated by powerful lasers. The relevance of such experiments is based on the establishment of scaling laws. News scaling laws in the frame of radiative ideal or resistive MHD are exposed. The results of the sizing and the interpretation of the POLAR experimental campaign of 2012 on LULI2000 installation are presented. (author) [fr

  18. Study on possible explosive reactions of sodium nitrate-bitumen mixtures initiated by a shock wave

    International Nuclear Information System (INIS)

    Savornin, J.; Vasseur, C.

    1986-01-01

    Potential hazards of the mixture sodium nitrate-bitumen obtained by embedding in bitumen liquid radioactive effluents concentrated by evaporation are studied in case of accidental shock wave. A theoretical evaluation based on thermodynamical data show a low probability, nevertheless different from zero. No explosion occurred in tests realized in severe conditions. In conclusion there is no risk of detonation of large quantity of bitumen-nitrates stored in 200-liter drum in radioactive waste storage [fr

  19. Study on coupled shock absorber system using four electromagnetic dampers

    International Nuclear Information System (INIS)

    Fukumori, Y; Hayashi, R; Okano, H; Suda, Y; Nakano, K

    2016-01-01

    Recently, the electromagnetic damper, which is composed of an electric motor, a ball screw, and a nut, was proposed. The electromagnetic damper has high responsiveness, controllability, and energy saving performance. It has been reported that it improved ride comfort and drivability. In addition, the authors have proposed a coupling method of two electromagnetic dampers. The method enables the characteristics of bouncing and rolling or pitching motion of a vehicle to be tuned independently. In this study, the authors increase the number of coupling of electromagnetic dampers from two to four, and propose a method to couple four electromagnetic dampers. The proposed method enables the characteristics of bouncing, rolling and pitching motion of a vehicle to be tuned independently. Basic experiments using proposed circuit and motors and numerical simulations of an automobile equipped with the proposed coupling electromagnetic damper are carried out. The results indicate the proposed method is effective. (paper)

  20. Exposure to whole-body vibration and mechanical shock: a field study of quad bike use in agriculture.

    Science.gov (United States)

    Milosavljevic, Stephan; McBride, David I; Bagheri, Nasser; Vasiljev, Radivoj M; Mani, Ramakrishnan; Carman, Allan B; Rehn, Borje

    2011-04-01

    The purpose of this study was to determine exposure to whole-body vibration (WBV) and mechanical shock in rural workers who use quad bikes and to explore how personal, physical, and workplace characteristics influence exposure. A seat pad mounted triaxial accelerometer and data logger recorded full workday vibration and shock data from 130 New Zealand rural workers. Personal, physical, and workplace characteristics were gathered using a modified version of the Whole Body Vibration Health Surveillance Questionnaire. WBVs and mechanical shocks were analysed in accordance with the International Standardization for Organization (ISO 2631-1 and ISO 2631-5) standards and are presented as vibration dose value (VDV) and mechanical shock (S(ed)) exposures. VDV(Z) consistently exceeded European Union (Guide to good practice on whole body vibration. Directive 2002/44/EC on minimum health and safety, European Commission Directorate General Employment, Social Affairs and Equal Opportunities. 2006) guideline exposure action thresholds with some workers exceeding exposure limit thresholds. Exposure to mechanical shock was also evident. Increasing age had the strongest (negative) association with vibration and shock exposure with body mass index (BMI) having a similar but weaker effect. Age, daily driving duration, dairy farming, and use of two rear shock absorbers created the strongest multivariate model explaining 33% of variance in VDV(Z). Only age and dairy farming combined to explain 17% of the variance for daily mechanical shock. Twelve-month prevalence for low back pain was highest at 57.7% and lowest for upper back pain (13.8%). Personal (age and BMI), physical (shock absorbers and velocity), and workplace characteristics (driving duration and dairy farming) suggest that a mix of engineered workplace and behavioural interventions is required to reduce this level of exposure to vibration and shock.

  1. Transmission-line resonators for the study of individual two-level tunneling systems

    Science.gov (United States)

    Brehm, Jan David; Bilmes, Alexander; Weiss, Georg; Ustinov, Alexey V.; Lisenfeld, Jürgen

    2017-09-01

    Parasitic two-level tunneling systems (TLS) emerge in amorphous dielectrics and constitute a serious nuisance for various microfabricated devices, where they act as a source of noise and decoherence. Here, we demonstrate a new test bed for the study of TLS in various materials which provides access to properties of individual TLS as well as their ensemble response. We terminate a superconducting transmission-line resonator with a capacitor that hosts TLS in its dielectric. By tuning TLS via applied mechanical strain, we observe the signatures of individual TLS strongly coupled to the resonator in its transmission characteristics and extract the coupling components of their dipole moments and energy relaxation rates. The strong and well-defined coupling to the TLS bath results in pronounced resonator frequency fluctuations and excess phase noise, through which we can study TLS ensemble effects such as spectral diffusion, and probe theoretical models of TLS interactions.

  2. The study of optimal conditions of electrochemical etching of tunnel electron microscopy tungsten tips

    International Nuclear Information System (INIS)

    Anguiano, E.; Aguilar, M.; Olivar, A.I.

    1996-01-01

    We present the experimental results obtained during the study made in the electrochemical etching of tunneling electron microscopy tungsten tips. The experiments was made using DC and two usual electrolytes: KOH and NaOH. For the tip preparation we used a electrochemical cell with stainless steel cathode and the tungsten wire as anode. the electrodes was introduced in a glass recipient containing the electrolytic solution. We study the effects of applied voltage, polish time, tip length and electrolyte concentration as process relevant parameters. The best condition for tip preparation was obtained with a metallurgical microscope and with a SEM.EDX and Auger analysis was made. The results shown the better tips was made with KOH as electrolyte with a limited concentration range (2-4 normal) and applied voltage (2-6 volts) (Author) 20 refs

  3. Residence time of contaminants released in surface coal mines -- a wind-tunnel study

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, R.S. [Environmental Protection Agency, Research Triangle Park, NC (United States)

    1994-12-31

    Surface coal mining operations (blasting, shoveling, loading, trucking, etc.) are sources of airborne particles. The 1990 Clean Air Act Amendments direct the EPA to analyze the accuracy of the Industrial Source Complex model and the AP-42 emission factors, and to make revisions as may be necessary to eliminate any significant over-prediction of air concentration of fugitive particles from surface coal mines. A wind-tunnel study was performed at the US EPA`s Fluid Modeling Facility to investigate dispersion from surface coal mines in support of the dispersion modeling activities. Described here is the portion of the study directed at determining the residence time that material released near the floor of a mine will stay within the mine.

  4. Study of Nb-oxide Nb-Pb film structures by tunnel scanning microscope

    International Nuclear Information System (INIS)

    Golyamina, E.M.; Troyanovskij, A.M.

    1986-01-01

    The surface of niobium films, which were earlier used to create niobium-niobium oxide-lead film structures on their base, was investigated, using tunnel scanning microscope. The results obtained agree well with the observed properties of these structures, containing josephson and tunnel junctions

  5. Occurrence of myofascial pain in patients with possible carpal tunnel syndrome - a single-blinded study

    DEFF Research Database (Denmark)

    Qerama, Erisela; Kasch, Helge; Fuglsang-Frederiksen, Anders

    2009-01-01

    There exits some similarity between symptoms of carpal tunnel syndrome (CTS) and myofascial pain related to trigger points (TPs) in the infraspinatus muscle.......There exits some similarity between symptoms of carpal tunnel syndrome (CTS) and myofascial pain related to trigger points (TPs) in the infraspinatus muscle....

  6. A Basic Study on Countermeasure Against Aerodynamic Force Acting on Train Running Inside Tunnel Using Air Blowing

    Science.gov (United States)

    Suzuki, Masahiro; Nakade, Koji

    A basic study of flow controls using air blowing was conducted to reduce unsteady aerodynamic force acting on trains running in tunnels. An air blowing device is installed around a model car in a wind tunnel. Steady and periodic blowings are examined utilizing electromagnetic valves. Pressure fluctuations are measured and the aerodynamic force acting on the car is estimated. The results are as follows: a) The air blowing allows reducing the unsteady aerodynamic force. b) It is effective to blow air horizontally at the lower side of the car facing the tunnel wall. c) The reduction rate of the unsteady aerodynamic force relates to the rate of momentum of the blowing to that of the uniform flow. d) The periodic blowing with the same frequency as the unsteady aerodynamic force reduces the aerodynamic force in a manner similar to the steady blowing.

  7. A study on the development of engineering plastic piston used in the shock absorber

    Science.gov (United States)

    Kim, Young-Ho; Bae, Won-Byong; Lim, Dong-Ju; Suh, Yun-Soo

    1998-08-01

    A piston is an important component of the shock absorber which determines comfortable riding and handling. Conventional piston is made of metal powder that is pressed in a mold, and then sintered at high temperatures below the melting point before machining processes such as drilling, sizing and teflon banding. This study aims at cutting down cost and weight, and improving the process by replacing the traditional sintering process used for manufacturing the shock absorber with the injection molding process adopting engineering plastics as raw material. To analyze the injection molding process, we used the commercial program, MOLDFLOW, and obtained an optimal combination of the process parameters. In addition, by comparing the engineering plastic piston with the metal powder piston through the formability and the performance experiments, we confirmed the availability of this alternative process suggested.

  8. STUDYING THE IMPACT OF GOVERNMENT EXPENDITURES SHOCKS ON MACROECONOMIC VARIABLES OF THE IRANIAN ECONOMY

    Directory of Open Access Journals (Sweden)

    Ahmad Assadzadeh

    2013-07-01

    Full Text Available This paper studies impact of government expenditures shocks on Gross DomesticProduct (GDP, personal consumption, trade balanceand effective exchange rate.To the purpose, time series data of Iranian macroeconomic variables were usedcovering from 1976 to 2007. Vector autoregressive (VAR model, forecast errorvariance decomposition and momentary reaction functions were used in order tostudy the impact of government expenditures shockson macroeconomic variablesof Iranian economy. Extracted results from the estimate of VAR model andanalyses of forecast error variance decomposition showed that: positive shocks ofthe government expenditures increase GDP and personal consumption butdecrease trade balance. Impact of government expenditures positive shocksdecrease effective exchange rate only in first yearthen government expendituresshocks had positive but very little impact on effective exchange rate.

  9. [Effectiveness of various dopamine doses in acute myocardial ischemia complicated by cardiogenic shock (an experimental study)].

    Science.gov (United States)

    Kipshidze, N N; Korotkov, A A; Marsagishvili, L A; Prigolashvili, T Sh; Bokhua, M R

    1981-06-01

    The effect of various doses of dopamine on the values of cardiac contractile and hemodynamic function under conditions of acute two-hour ischemia complicated by cardiogenic shock was studied in 27 experiments on dogs. In a dose of 5 microgram/kg/min dopamine caused an optimum increase in cardiac productive capacity, reduction of peripheral resistance, adequate increase in coronary circulation and decrease in ST segment depression on the ECG. Infusion of 10 microgram/kg/min dopamine usually caused myocardial hyperfunction with an increase in total peripheral resistance and cardiac performance. Maximum dopamine doses (10 microgram/kg/min and more) were effective in the areactive form of cardiogenic shock. In longterm dopamine infusion it is necessary to establish continuous control over the hemodynamic parameters and the ECG to prevent aggravation of ischemia and for stage-by-stage reduction of the drug concentration and determination of the minimum maintenance dose.

  10. The impact of oil-price shocks on Hawaii's economy: A case study using vector autoregression

    International Nuclear Information System (INIS)

    Gopalakrishnan, C.; Tian, X.; Tran, D.

    1991-01-01

    The effects of oil-price shocks on the macroeconomic performance of a non-oil-producing, oil-importing state are studied in terms of Hawaii's experience (1974-1986) using Vector Autoregression (VAR). The VAR model contains three macrovariables-real oil price, interest rate, and real GNP, and three regional variable-total civilian labor force, Honolulu consumer price index, and real personal income. The results suggested that oil-price shock had a positive effect on interest rate as well as local price (i.e., higher interest and higher local price), but a negative influence on real GNP. The negative income effect, however, was offset by the positive employment effect. The price of oil was found to be exogenous to all other variables in the system. The macrovariables exerted a pronounced impact on Hawaii's economy, most notably on consumer price

  11. Correlating nerve conduction studies and clinical outcome measures on carpal tunnel syndrome: lessons from a randomized controlled trial

    NARCIS (Netherlands)

    Schrijver, H.M.; Gerritsen, A.A.M.; Strijers, R.L.; Uitdehaag, B.M.J.; Scholten, R.J.P.M.; de Vet, H.C.W.; Bouter, L.M.

    2005-01-01

    The reported relationships between nerve conduction studies (NCS) and outcome measures in carpal tunnel syndrome (CTS) are weak to moderate. However, selection of patients may have confounded nonrandomized studies. NCS have potentially great value in selecting patients for a specific treatment and

  12. Self streamlining wind tunnel: Further low speed testing and final design studies for the transonic facility

    Science.gov (United States)

    Wolf, S. W. D.

    1978-01-01

    Work was continued with the low speed self streamlining wind tunnel (SSWT) using the NACA 0012-64 airfoil in an effort to explain the discrepancies between the NASA Langley low turbulence pressure tunnel (LTPT) and SSWT results obtained with the airfoil stalled. Conventional wind tunnel corrections were applied to straight wall SSWT airfoil data, to illustrate the inadequacy of standard correction techniques in circumstances of high blockage. Also one SSWT test was re-run at different air speeds to investigate the effects of such changes (perhaps through changes in Reynold's number and freestream turbulence levels) on airfoil data and wall contours. Mechanical design analyses for the transonic self-streamlining wind tunnel (TSWT) were completed by the application of theoretical airfoil flow field data to the elastic beam and streamline analysis. The control system for the transonic facility, which will eventually allow on-line computer operation of the wind tunnel, was outlined.

  13. Studies on the robustness of shock-ignited laser fusion targets

    International Nuclear Information System (INIS)

    Atzeni, S; Schiavi, A; Marocchino, A

    2011-01-01

    Several aspects of the sensitivity of a shock-ignited inertial fusion target to variation of parameters and errors or imperfections are studied by means of one-dimensional and two-dimensional numerical simulations. The study refers to a simple all-DT target, initially proposed for fast ignition (Atzeni et al 2007 Phys. Plasmas 7 052702) and subsequently shown to be also suitable for shock ignition (Ribeyre et al 2009 Plasma Phys. Control. Fusion 51 015013). It is shown that the growth of both Richtmyer-Meshkov and Rayleigh-Taylor instability (RTI) at the ablation front is reduced by laser pulses with an adiabat-shaping picket. An operating window for the parameters of the ignition laser spike is described; the threshold power depends on beam focusing and synchronization with the compression pulse. The time window for spike launch widens with beam power, while the minimum spike energy is independent of spike power. A large parametric scan indicates good tolerance (at the level of a few percent) to target mass and laser power errors. 2D simulations indicate that the strong igniting shock wave plays an important role in reducing deceleration-phase RTI growth. Instead, the high hot-spot convergence ratio (ratio of initial target radius to hot-spot radius at ignition) makes ignition highly sensitive to target mispositioning.

  14. Numerical study of shock-wave/boundary layer interactions in premixed hydrogen-air hypersonic flows

    Science.gov (United States)

    Yungster, Shaye

    1991-01-01

    A computational study of shock wave/boundary layer interactions involving premixed combustible gases, and the resulting combustion processes is presented. The analysis is carried out using a new fully implicit, total variation diminishing (TVD) code developed for solving the fully coupled Reynolds-averaged Navier-Stokes equations and species continuity equations in an efficient manner. To accelerate the convergence of the basic iterative procedure, this code is combined with vector extrapolation methods. The chemical nonequilibrium processes are simulated by means of a finite-rate chemistry model for hydrogen-air combustion. Several validation test cases are presented and the results compared with experimental data or with other computational results. The code is then applied to study shock wave/boundary layer interactions in a ram accelerator configuration. Results indicate a new combustion mechanism in which a shock wave induces combustion in the boundary layer, which then propagates outwards and downstream. At higher Mach numbers, spontaneous ignition in part of the boundary layer is observed, which eventually extends along the entire boundary layer at still higher values of the Mach number.

  15. Is Tamsulosin Effective after Shock Wave Lithotripsy for Pediatric Renal Stones? A Randomized, Controlled Study.

    Science.gov (United States)

    Shahat, Ahmed; Elderwy, Ahmad; Safwat, Ahmed S; Abdelkawi, Islam F; Reda, Ahmed; Abdelsalam, Yasser; Sayed, Mohamed; Hammouda, Hisham

    2016-04-01

    We assessed the effect of tamsulosin as an adjunctive therapy after shock wave lithotripsy for pediatric single renal pelvic stones. A total of 120 children with a unilateral single renal pelvic stone were included in a prospective randomized, controlled study. All children were randomized to 2 equal groups. Group 1 received tamsulosin (0.01 mg/kg once daily) as adjunctive therapy after shock wave lithotripsy in addition to paracetamol while group 2 received paracetamol only. Stone clearance was defined as no renal stone fragments or fragments less than 3 mm and no pelvicalyceal system dilatation. Our study included 69 boys and 51 girls with a median age of 3.5 years and a median stone size of 1.2 cm. There was no statistically significant difference between groups 1 and 2 in stone or patient criteria. Of the children 99 (82.5%) achieved stone clearance after the first session, including 50 in group 1 and 49 in group 2. All children in each group were cleared of stones after the second session. The overall complication rate was 14.2%. There was no statistically significant difference between single session stone clearance rates (p = 0.81) and complications rates (p = 0.432) in either group. On multivariate analysis using logistic regression smaller stone size (p = 0.016) and radiopaque stones (p = 0.019) were the only predictors of stone clearance at a single shock wave lithotripsy session. Tamsulosin therapy did not affect stone clearance (p = 0.649). Tamsulosin does not seem to improve renal stone clearance. Smaller and radiopaque renal stones have more chance of clearance after shock wave lithotripsy for pediatric single renal pelvic stones. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  16. Study of the dynamic fragmentation of laser shock-loaded metallic target

    International Nuclear Information System (INIS)

    Lescoute, E.

    2010-01-01

    The irradiation of a metallic target by a high power laser pulse induces a shock wave in the material. Under some conditions, it leads to the production of high velocity ejecta which can damage the optical environment (lenses, mirrors, windows, etc.). With the ongoing development of high energy laser facilities designed to achieve inertial confinement fusion, such as the Laser MegaJoule in France or the National Ignition Facility in the USA, the question of debris ejection from metallic samples subjected to intense laser irradiation has become a key issue. It is necessary to understand fragmentation processes induced by laser shock, and to anticipate and quantify generated fragments, in order to design suitable protections and experiments, and to preserve laser facilities. The main fragmentation processes which can occur in a laser-shock-loaded metallic target and generate high velocity ejecta are: (i) micro-jetting, which occurs upon reflection of the incident compressive front from the free surface, (ii) spallation, which is due to the later interaction of the release wave reflected from that surface with the incident unloading wave and (iii) dynamic punching of thin targets. Experimental campaigns have been performed on high energy laser facilities in the Centre d'Etudes Scientifiques et Techniques d'Aquitaine (CESTA, CEA, Alise facility) and in the Laboratoire pour l'Utilisation des Lasers Intenses (LULI, Ecole Polytechnique, LULI 2000 facility). Gold and aluminium have been mainly studied because they are the two main metallic components of the target which will be used to achieved the inertial confinement fusion. Specific diagnostics have been developed and used during these experiments to study the dynamic fragmentation: transverse shadowgraphy, free surface velocity measurement and recovery of generated fragments. Experimental results have been compared with numerical predictions obtained with a bi-dimensional hydrodynamic code, where a specific numerical

  17. Fluid dynamics of the shock wave reactor

    Science.gov (United States)

    Masse, Robert Kenneth

    2000-10-01

    High commercial incentives have driven conventional olefin production technologies to near their material limits, leaving the possibility of further efficiency improvements only in the development of entirely new techniques. One strategy known as the Shock Wave Reactor, which employs gas dynamic processes to circumvent limitations of conventional reactors, has been demonstrated effective at the University of Washington. Preheated hydrocarbon feedstock and a high enthalpy carrier gas (steam) are supersonically mixed at a temperature below that required for thermal cracking. Temperature recovery is then effected via shock recompression to initiate pyrolysis. The evolution to proof-of-concept and analysis of experiments employing ethane and propane feedstocks are presented. The Shock Wave Reactor's high enthalpy steam and ethane flows severely limit diagnostic capability in the proof-of-concept experiment. Thus, a preliminary blow down supersonic air tunnel of similar geometry has been constructed to investigate recompression stability and (especially) rapid supersonic mixing necessary for successful operation of the Shock Wave Reactor. The mixing capabilities of blade nozzle arrays are therefore studied in the air experiment and compared with analytical models. Mixing is visualized through Schlieren imaging and direct photography of condensation in carbon dioxide injection, and interpretation of visual data is supported by pressure measurement and flow sampling. The influence of convective Mach number is addressed. Additionally, thermal behavior of a blade nozzle array is analyzed for comparison to data obtained in the course of succeeding proof-of-concept experiments. Proof-of-concept is naturally succeeded by interest in industrial adaptation of the Shock Wave Reactor, particularly with regard to issues involving the scaling and refinement of the shock recompression. Hence, an additional, variable geometry air tunnel has been constructed to study the parameter

  18. Properties of a Laser Shock Wave in Al-Cu Alloy under Elevated Temperatures: A Molecular Dynamics Simulation Study

    Directory of Open Access Journals (Sweden)

    Xiankai Meng

    2017-01-01

    Full Text Available The laser shock wave (LSW generated by the interaction between a laser and a material has been widely used in laser manufacturing, such as laser shock peening and laser shock forming. However, due to the high strain rate, the propagation of LSW in materials, especially LSW at elevated temperatures, is difficult to study through experimental methods. A molecular dynamics simulation was used in this study to investigate the propagation of LSW in an Al-Cu alloy. The Hugoniot relations of LSW were obtained at different temperatures and the effects of elevated temperatures on shock velocity and shock pressure were analyzed. Then the elastic and plastic wave of the LSW was researched. Finally, the evolution of dislocations induced by LSW and its mechanism under elevated temperatures was explored. The results indicate that the shock velocity and shock pressure induced by LSW both decrease with the increasing temperatures. Moreover, the velocity of elastic wave and plastic wave both decrease with the increasing treatment temperature, while their difference decreases as the temperature increases. Moreover, the dislocation atoms increases with the increasing temperatures before 2 ps, while it decreases with the increasing temperatures after 2 ps. The reason for the results is related to the formation and evolution of extended dislocations.

  19. Experimental Study of the Effect of Water Mist Location On Blast Overpressure Attenuation in A Shock Tube

    Science.gov (United States)

    Mataradze, Edgar; Chikhradze, Nikoloz; Bochorishvili, Nika; Akhvlediani, Irakli; Tatishvili, Dimitri

    2017-12-01

    Explosion protection technologies are based on the formation of a shock wave mitigation barrier between the protection site and the explosion site. Contemporary protective systems use water mist as an extinguishing barrier. To achieve high effectiveness of the protective system, proper selection of water mist characteristics is important. The main factors defining shock wave attenuation in water mist include droplet size distribution, water concentration in the mist, droplet velocity and geometric properties of mist. This paper examines the process of attenuation of shock waves in mist with droplets ranging from 25 to 400 microns under different conditions of water mist location. Experiments were conducted at the Mining Institute with the use of a shock tube to study the processes of explosion suppression by a water mist barrier. The shock tube consists of a blast chamber, a tube, a system for the dosed supply of water, sensors, data recording equipment, and a process control module. Shock wave overpressure reduction coefficient was studied in the shock tube under two different locations of water mist: a) when water mist is created in direct contact with blast chamber and b) the blast chamber and the mist are separated by air space. It is established that in conditions when the air space distance between the blast chamber and the mist is 1 meter, overpressure reduction coefficient is 1.5-1.6 times higher than in conditions when water mist is created in direct contact with blast chamber.

  20. Band structure of Heusler compounds studied by photoemission and tunneling spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arbelo Jorge, Elena

    2011-07-01

    Heusler compounds are key materials for spintronic applications. They have attracted a lot of interest due to their half-metallic properties predicted by band structure calculations. The aim of this work is to evaluate experimentally the validity of the predictions of half metallicity by band structure calculations for two specific Heusler compounds, Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} and Co{sub 2}MnGa. Two different spectroscopy methods for the analysis of the electronic properties were used: Angular Resolved Ultraviolet Photoemission Spectroscopy (ARUPS) and Tunneling Spectroscopy. Heusler compounds are prepared as thin films by RF-sputtering in an ultra high vacuum system. For the characterization of the samples, bulk and surface crystallographic and magnetic properties of Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} and Co{sub 2}MnGa are studied. X-ray and electron diffraction reveal a bulk and surface crossover between two different types of sublattice order (from B2 to L2{sub 1}) with increasing annealing temperature. X-ray magnetic circular dichroism results show that the magnetic properties in the surface and bulk are identical, although the magnetic moments obtained are 5 % below from the theoretically predicted. By ARUPS evidence for the validity of the predicted total bulk density of states (DOS) was demonstrated for both Heusler compounds. Additional ARUPS intensity contributions close to the Fermi energy indicates the presence of a specific surface DOS. Moreover, it is demonstrated that the crystallographic order, controlled by annealing, plays an important role on broadening effects of DOS features. Improving order resulted in better defined ARUPS features. Tunneling magnetoresistance measurements of Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} and Co{sub 2}MnGa based MTJ's result in a Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} spin polarization of 44 %, which is the highest experimentally obtained value for this compound, although it is lower than the 100 % predicted. For Co

  1. Heavy-duty diesel vehicles dominate vehicle emissions in a tunnel study in northern China.

    Science.gov (United States)

    Song, Congbo; Ma, Chao; Zhang, Yanjie; Wang, Ting; Wu, Lin; Wang, Peng; Liu, Yan; Li, Qian; Zhang, Jinsheng; Dai, Qili; Zou, Chao; Sun, Luna; Mao, Hongjun

    2018-05-09

    The relative importance of contributions of gasoline vehicles (GVs) and diesel vehicles (DVs), heavy-duty diesel vehicles (HDDVs) and non-HDDVs to on-road vehicle emissions remains unclear. Vehicle emission factors (EFs), including fine particulate matter (PM 2.5 ), NO-NO 2 -NO x , and carbon monoxide (CO), were measured (August 4-18, 2017) in an urban tunnel in Tianjin, northern China. The average EFs (mg km -1 veh -1 ) of the fleet were as follows: 9.21 (95% confidence interval: 1.60, 23.07) for PM 2.5 , 62.08 (21.21, 138.25) for NO, 20.42 (0.79, 45.48) for NO 2 , 83.72 (26.29, 162.87) for NO x , and 284.54 (18.22, 564.67) for CO. The fleet-average EFs exhibited diurnal variations, due to diurnal variations in the proportion of HDDVs in the fleet, though the hourly proportion of HDDVs never exceeded 10% during the study period. The reconstructed average EFs for on-road vehicle emissions of PM 2.5 , NO, NO 2 , and NO x , and CO were approximately 2.2, 1.7, 1.5, 2.0, and 1.6 times as much as those in the tunnel, respectively, due to the higher HDDV fractions in the whole city than those in the tunnel. The EFs of PM 2.5 , NO, NO 2 , and NO x , and CO from each HDDV were approximately 75, 81, 24, 65, and 33 times of those from each non-HDDV, respectively. HDDVs were responsible for approximately 81.92%, 83.02%, 59.79%, 79.79%, and 66.77% of the total PM 2.5 , NO, NO 2 , and NO x , and CO emissions from on-road vehicles in Tianjin, respectively. DVs, especially HDDVs, are major sources of on-road PM 2.5 , NO-NO 2 -NO x , and CO emissions in northern China. The contribution of HDDVs to fleet emissions calculated by the EFs from Chinese 'on-road vehicle emission inventory guidebook' were underestimated, as compared to our results. The EFs from on-road vehicles should be updated due to the rapid progression of vehicle technology combined with emission standards in China. The management and control of HDDV emissions have become urgent to reduction of on-road vehicle

  2. Effect of turbulence intensity on PM emission of heavy duty diesel trucks - Wind tunnel studies

    Science.gov (United States)

    Littera, D.; Cozzolini, A.; Besch, M.; Carder, D.; Gautam, M.

    2017-08-01

    Stringent emission regulations have forced drastic technological improvements in diesel aftertreatment systems, particularly in reducing Particulate Matter (PM) emissions. The formation and evolution of PM from modern engines are more sensitive to overall changes in the dilution process, such as rapidity of mixing, background PM present in the air. These technological advancements were made in controlled laboratory environments compliant with measurement standards (i.e. Code of Federal Regulation CFR in the USA) and are not fully representative of real-world emissions from these engines or vehicles. In light of this, a specifically designed and built wind tunnel by West Virginia University (WVU) is used for the study of the exhaust plume of a heavy-duty diesel vehicle, providing a better insight in the dilution process and the representative nanoparticles emissions in a real-world scenario. The subsonic environmental wind tunnel is capable of accommodating a full-sized heavy-duty truck and generating wind speeds in excess of 50mph. A three-dimensional gantry system allows spanning the test section and sample regions in the plume with accuracy of less than 5 mm. The gantry system is equipped with engine exhaust gas analyzers and PM sizing instruments. The investigation involves three different heavy-duty Class-8 diesel vehicles representative of three emission regulation standards, namely a US-EPA 2007 compliant, a US-EPA 2010 compliant, and a baseline vehicle without any aftertreatment technologies as a pre US-EPA 2007, respectively. The testing procedure includes three different vehicle speeds: idling, 20mph, and 35mph. The vehicles were tested on WVU's medium-duty chassis dynamometer, with the load applied to the truck reflecting the road load equation at the corresponding vehicle test speeds. Wind tunnel wind speed and vehicle speed were maintained in close proximity to one another during the entire test. Results show that the cross-sectional plume area

  3. Studies of superconductors using a low-temperature, high-field scanning tunneling microscope

    International Nuclear Information System (INIS)

    Kirtley, J.R.; Feenstra, R.M.; Fein, A.P.

    1988-01-01

    We have developed a scanning tunneling microscope (STM) capable of operating at temperatures as low as 0.4 K and fields as high as 8 T. We have used this STM to study the energy gap of the high-T/sub c/ superconductors La--Sr--Cu--O and Y--Ba--Cu--O. We find that the reduced gap for these oxide superconductors falls in the range 3<2Δ/k/sub B/T/sub c/<7, for polycrystalline, single-crystal, and thin-film samples. We have also simultaneously imaged the surface topography and superconducting energy gap for thin films of the granular superconductor NbN. We occasionally see regions with smaller best-fit gaps that correlate with surface topographical features, but have been unable so far to image flux vortices

  4. QUALITY CONTROL IN PRECAST PRODUCTION A case study on Tunnel Segment Manufacture

    Directory of Open Access Journals (Sweden)

    Yee Weng Cheong

    2005-01-01

    Full Text Available Quality control forms an integral part of precast production. An efficient quality system is most critical in the mass production of precast components in any project. In this study, the quality control system implemented in a precast factory is discussed. The precast factory is set up for the manufacture of large quantity of tunnel segments under a contract. Processes in the precast manufacture are discussed with respect to the control procedures in the quality inspection plan. The standard tests involved, roles of inspectors and corrective actions on-site are highlighted. Critical issues pertaining to the productivity and quality of precast production are reviewed. These include the quality of staff and maintenance, which could potentially affect the efficiency of the quality system. Some considerations should also be given to improve the workflow and productivity of the plant.

  5. Preliminary studies on the Marcoule site, using a wind-tunnel

    International Nuclear Information System (INIS)

    Chassany, J.Ph.; Salaun-Penquer, G.

    1961-01-01

    The tests were carried out in the 3.30 x 2.20 subsonic elliptical wind-tunnel of the Marseille Institute of fluid mechanics, on a 1/1000 scale model measuring 3 m x 3 m. The aerodynamic field developing above the site, made visible by ammonium, hydro-chlorate fumes, and the residues were observed and filmed by means of a synchronised cine-camera with stroboscopic lighting for 4 wind directions. The fall-out from the various waste products was obtained from a spraying of lead acetate solution on the model and hydrogen sulphide emissions. The zones of maximum pollution can be determined from a study of the film taken during the blackening of the spots. (author) [fr

  6. Scanning tunneling microscopy studies of organic monolayers adsorbed on the rhodium(111) crystal surface

    Energy Technology Data Exchange (ETDEWEB)

    Cernota, Paul Davis [Univ. of California, Berkeley, CA (United States)

    1999-08-01

    Scanning Tunneling Microscopy studies were carried out on ordered overlayers on the (111) surface of rhodium. These adsorbates include carbon monoxide (CO), cyclohexane, cyclohexene, 1,4-cyclohexadiene, para-xylene, and meta-xylene. Coadsorbate systems included: CO with ethylidyne, CO with para- and meta-xylene, and para-xylene with meta-xylene. In the case of CO, the structure of the low coverage (2x2) overlayer has been observed. The symmetry of the unit cell in this layer suggests that the CO is adsorbed in the 3-fold hollow sites. There were also two higher coverage surface structures with (√7x√7) unit cells. One of these is composed of trimers of CO and has three CO molecules in each unit cell. The other structure has an additional CO molecule, making a total of four. This extra CO sits on a top site.

  7. Feasibility study for a B-meson factory in the CERN ISR tunnel

    International Nuclear Information System (INIS)

    Nakada, T.

    1990-01-01

    A feasibility study has been made for a B-meson factory, using the ISR tunnel and the LEP injector at CERN. An electron-positron collider operated with asymmetric beam energies of 8 and 3.5 GeV at a luminosity of 10 34 cm -2 s -1 will permit decisive answers on the question of CP violation within the framework of the Standard Model. This report outlines the physics motivation and detector requirements and gives a description of the machine design. It is proposed that the design goal is reached in two stages, with a collider with two rings of equal size. In the first stage a luminosity of 10 33 cm -2 s -1 may be achieved, allowing a rich programme of charm, beauty and τ-lepton physics. A further tenfold increase of the luminosity would require additional R and D on various machine aspects. (orig.)

  8. Scanning tunneling microscopy study of a newly proposed topological insulator ZrTe{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, Timo; Gragnaniello, Luca; Fonin, Mikhail [Universitaet Konstanz (Germany); Autes, Gabriel; Berger, Helmuth; Yazyev, Oleg [Institute of Condensed Matter Physics, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Manzoni, Giulia [Universita degli Studi di Trieste (Italy); Crepaldi, Alberto; Parmigiani, Fulvio [Elettra-Sincrotrone Trieste, Trieste (Italy)

    2016-07-01

    Topological insulators belong to a new kind of material class that posses robust gapless states inside the insulating bulk gap, which makes them promising candidates for achieving dissipationless transport devices. We present a Scanning tunneling microscopy (STM) and spectroscopy (STS) study on a layered material ZrTe{sub 5}, a promising candidate for a new topological insulator. The crystal structure could clearly be identified in topography images. STM measurements enabled direct imaging of standing waves at steps and defects. The standing waves show a clearly dispersive character. Furthermore STS measurements are in good agreement with density functional theory calculations and reveal Landau quantization with applied magnetic field. Comparison with data obtained by angle resolved photoemission spectroscopy allows for detailed insights into the electronic properties of this material.

  9. Cooling modifies mixed median and ulnar palmar studies in carpal tunnel syndrome.

    Science.gov (United States)

    Araújo, Rogério Gayer Machado de; Kouyoumdjian, João Aris

    2007-09-01

    Temperature is an important and common variable that modifies nerve conduction study parameters in practice. Here we compare the effect of cooling on the mixed palmar median to ulnar negative peak-latency difference (PMU) in electrodiagnosis of carpal tunnel syndrome (CTS). Controls were 22 subjects (19 women, mean age 42.1 years, 44 hands). Patients were diagnosed with mild symptomatic CTS (25 women, mean age 46.6 years, 34 hands). PMU was obtained at the usual temperature, >32 degrees C, and after wrist/hand cooling to PMU and mixed ulnar palmar latency in patients versus controls. We concluded that cooling significantly modifies the PMU. We propose that the latencies of compressed nerve overreact to cooling and that this response could be a useful tool for incipient CTS electrodiagnosis. There was a significant latency overreaction of the ulnar nerve to cooling in CTS patients. We hypothesize that subclinical ulnar nerve compression is associated with CTS.

  10. Spin-resolved tunneling studies of the exchange field in EuS/Al bilayers.

    Science.gov (United States)

    Xiong, Y M; Stadler, S; Adams, P W; Catelani, G

    2011-06-17

    We use spin-resolved electron tunneling to study the exchange field in the Al component of EuS/Al bilayers, in both the superconducting and normal-state phases of the Al. Contrary to expectation, we show that the exchange field H(ex) is a nonlinear function of applied field, even in applied fields that are well beyond the EuS coercive field. Furthermore, the magnitude H(ex) is unaffected by the superconducting phase. In addition, H(ex) decreases significantly with increasing temperature in the temperature range of 0.1-1 K. We discuss these results in the context of recent theories of generalized spin-dependent boundary conditions at a superconductor-ferromagnet interface.

  11. A study of interpolation method in diagnosis of carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    Alireza Ashraf

    2013-01-01

    Full Text Available Context: The low correlation between the patients′ signs and symptoms of carpal tunnel syndrome (CTS and results of electrodiagnostic tests makes the diagnosis challenging in mild cases. Interpolation is a mathematical method for finding median nerve conduction velocity (NCV exactly at carpal tunnel site. Therefore, it may be helpful in diagnosis of CTS in patients with equivocal test results. Aim: The aim of this study is to evaluate interpolation method as a CTS diagnostic test. Settings and Design: Patients with two or more clinical symptoms and signs of CTS in a median nerve territory with 3.5 ms ≤ distal median sensory latency <4.6 ms from those who came to our electrodiagnostic clinics and also, age matched healthy control subjects were recruited in the study. Materials and Methods: Median compound motor action potential and median sensory nerve action potential latencies were measured by a MEDLEC SYNERGY VIASIS electromyography and conduction velocities were calculated by both routine method and interpolation technique. Statistical Analysis Used: Chi-square and Student′s t-test were used for comparing group differences. Cut-off points were calculated using receiver operating characteristic curve. Results: A sensitivity of 88%, specificity of 67%, positive predictive value (PPV and negative predictive value (NPV of 70.8% and 84.7% were obtained for median motor NCV and a sensitivity of 98.3%, specificity of 91.7%, PPV and NPV of 91.9% and 98.2% were obtained for median sensory NCV with interpolation technique. Conclusions: Median motor interpolation method is a good technique, but it has less sensitivity and specificity than median sensory interpolation method.

  12. Effectiveness of PELOID therapy in carpal tunnel syndrome: A randomized controlled single blind study

    Science.gov (United States)

    Metin Ökmen, Burcu; Kasapoğlu Aksoy, Meliha; Güneş, Aygül; Eröksüz, Riza; Altan, Lale

    2017-08-01

    Carpal tunnel syndrome(CTS) is the most common neuromuscular cause of upper extremity disability. We aimed to investigate the effectiveness of peloid therapy in patients with CTS. This randomized, controlled, single-blind study enrolled 70 patients between the ages of 30 to 65 who had a diagnosis of either mild, mild-to-moderate, or moderate CTS. The patients were randomized into two groups using random number table. In the first group, (Group 1)( n = 35), patients were given splint (every night for 6 weeks) + peloid treatment(five consecutive days a week for 2 weeks) and in the second group, (Group 2)( n = 28), patients received splint treatment(every night for 6 weeks) alone. The patients were assessed by using visual analog scale(VAS) for pain, electroneuromyography(ENMG), the Boston Carpal Tunnel Syndrome Questionnaire(BCTSQ), hand grip strength(HGS), finger grip strength(FGS), and Short Form-12(SF-12). The data were obtained before treatment(W0), immediately after treatment(W2), and one month after treatment(W6). Both in Group 1 and 2, there was a statistically significant improvement in all the evaluation parameters at W2 and W6 when compared to W0( p < 0.05). Comparison of the groups with each other revealed significantly better results for VAS, BCTSQ, mSNCV, SF-12 in Group 1 than in Group 2 at W2( p < 0.05). There was also a statistically significant difference in favor of Group 1 for VAS, BCTSQ, FGS and MCS at W6 when compared to W0 ( p < 0.05). The results of our study demonstrated that in patients with CTS; peloid + splint treatment was more effective than splint treatment alone in pain, functionality and life quality both at after treatment(W2) and one month after treatment (W6). We may suggest peloid as a supplementary therapeutic agent in CTS.

  13. Extracorporeal shock wave lithotripsy of intrahepatic stones with piezoelectric lithotriptor: in vitro study

    International Nuclear Information System (INIS)

    Choi, Byung Ihn; Yoon, Chong Hyun; Park, Yong Hyun; Han, Joon Koo; Yoon, Yong Bum; Shin, Yong Moon; Kim, Jin Q; Kim, Chu Wan; Han, Man Chung

    1992-01-01

    This study was designed to investigate effectiveness of fragmentation during lithotripsy using 103 intrahepatic stones collected from 10 patients, who had previously undergone biliary surgery. The size of each stone was measured and sonography was performed for the evaluation of the sonographic type of the stones. In vitro lithotripsy was performed on individual stones using piezoelectric lithotriptor to evaluate the fragmentation rate and average number of shock waves for fragmentation. Chemical analysis of each stone was done to determine chemical composition including calcium, bilirubin, and cholesterol. The size of the stones was from 5 mm to 20 mm in diameter. Sonographic type I (echo of whole stone with posterior acoustic shadow) was 68, and type II (are-like strong surface echo of stone with clear posterior acoustic shadow) was 35 in number. The majority (78%) of stones in group I (5-9 mm in diameter) showed sonographic type I characteristics, and 62% of stones in group 3 (larger than 15 mm in diameter) showed sonographic type II characteristics. There was a positive correlation between the size and sonographic type of stones. Fragmentation rates of stones were 100% in group I, 71.9% in group 2 (10-15 mm in diameter), 43.8% in group 3, respectively. Fragmentation rates of stones with sonographic type I and II were 91.2%, 65.7%, respectively. The average number of shock waves for partial and complete fragmentation was 2753 ± 4937 and 6219 ± 10133, respectively. There was a positive correlation between the number of shock waves for fragmentation and diameter of stones (r = 0.618, ρ < 0.05). There was no correlation between the number of shock waves for fragmentation and chemical composition of stones. In conclusion, the most important variable determining the degree of fragmentation of intrahepatic stones using ESWL is not their chemical composition but their size and sonographic characteristics

  14. Extracorporeal shock wave lithotripsy of intrahepatic stones with piezoelectric lithotriptor: in vitro study

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Byung Ihn; Yoon, Chong Hyun; Park, Yong Hyun; Han, Joon Koo; Yoon, Yong Bum; Shin, Yong Moon; Kim, Jin Q; Kim, Chu Wan; Han, Man Chung [Seoul National University, College of Medicine, Seoul (Korea, Republic of)

    1992-05-15

    This study was designed to investigate effectiveness of fragmentation during lithotripsy using 103 intrahepatic stones collected from 10 patients, who had previously undergone biliary surgery. The size of each stone was measured and sonography was performed for the evaluation of the sonographic type of the stones. In vitro lithotripsy was performed on individual stones using piezoelectric lithotriptor to evaluate the fragmentation rate and average number of shock waves for fragmentation. Chemical analysis of each stone was done to determine chemical composition including calcium, bilirubin, and cholesterol. The size of the stones was from 5 mm to 20 mm in diameter. Sonographic type I (echo of whole stone with posterior acoustic shadow) was 68, and type II (are-like strong surface echo of stone with clear posterior acoustic shadow) was 35 in number. The majority (78%) of stones in group I (5-9 mm in diameter) showed sonographic type I characteristics, and 62% of stones in group 3 (larger than 15 mm in diameter) showed sonographic type II characteristics. There was a positive correlation between the size and sonographic type of stones. Fragmentation rates of stones were 100% in group I, 71.9% in group 2 (10-15 mm in diameter), 43.8% in group 3, respectively. Fragmentation rates of stones with sonographic type I and II were 91.2%, 65.7%, respectively. The average number of shock waves for partial and complete fragmentation was 2753 {+-} 4937 and 6219 {+-} 10133, respectively. There was a positive correlation between the number of shock waves for fragmentation and diameter of stones (r = 0.618, {rho} < 0.05). There was no correlation between the number of shock waves for fragmentation and chemical composition of stones. In conclusion, the most important variable determining the degree of fragmentation of intrahepatic stones using ESWL is not their chemical composition but their size and sonographic characteristics.

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

    Science.gov (United States)

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

    2008-12-01

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

  16. Thiamine in septic shock patients with alcohol use disorders: An observational pilot study.

    Science.gov (United States)

    Holmberg, Mathias Johan; Moskowitz, Ari; Patel, Parth Vijay; Grossestreuer, Anne Victoria; Uber, Amy; Stankovic, Nikola; Andersen, Lars Wiuff; Donnino, Michael William

    2018-02-01

    Alcohol-use disorders (AUDs) have been associated with increased sepsis-related mortality. As patients with AUDs are often thiamine deficient, we investigated practice patterns relating to thiamine administration in patients with AUDs presenting with septic shock and explored the association between receipt of thiamine and mortality. We performed a retrospective cohort study of patients presenting with septic shock between 2008 and 2014 at a single tertiary care center. We identified patients with an AUD diagnosis, orders for microbial cultures and use of antibiotics, vasopressor dependency, and lactate levels≥4mmol/L. We excluded those who received thiamine later than 48h of sepsis onset. We included 53 patients. Thirty-four (64%) patients received thiamine. Five patients (15%) received their first thiamine dose in the emergency department. The median time to thiamine administration was 9 (quartiles: 4, 18) hours. The first thiamine dose was most often given parenterally (68%) and for 100mg (88%). In those receiving thiamine, 15/34 (44%) died, compared to 15/19 (79%) of those not receiving thiamine, p=0.02. A considerable proportion of patients with AUDs admitted for septic shock do not receive thiamine. Thiamine administration in this patient population was associated with decreased mortality. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Quantitative Studies of Sublingual PCO2 as a Resuscitation End-Point in the Diagnosis and Treatment of Hemorrhagic Shock

    National Research Council Canada - National Science Library

    Ivatury, Pao

    2005-01-01

    This clinical study is examining the relationship between sublingual PCO2 (PslCO2) to real-time changes in microcirculatory blood flow of the sublingual mucosa in victims of traumatic and hemorrhagic shock...

  18. Miniature shock tube for laser driven shocks.

    Science.gov (United States)

    Busquet, Michel; Barroso, Patrice; Melse, Thierry; Bauduin, Daniel

    2010-02-01

    We describe in this paper the design of a miniature shock tube (smaller than 1 cm(3)) that can be placed in a vacuum vessel and allows transverse optical probing and longitudinal backside extreme ultraviolet emission spectroscopy in the 100-500 A range. Typical application is the study of laser launched radiative shocks, in the framework of what is called "laboratory astrophysics."

  19. STUDY ON THE BLASTING SEISMIC DAMAGE CONTROL TECHNOLOGY FOR SMALL SPACING SOFT ROCK TUNNEL

    Directory of Open Access Journals (Sweden)

    Yang Chengzhong

    2017-07-01

    Full Text Available With a lot construction of transportation infrastructure in Chinese mountainous area, because of its unique advantages such as less land occupation, beautiful appearance and convenient route planning, small spacing tunnels are widely used. The shallow buried tunnel with small spacing, the blasting excavation will lead to tunnel surrounding rock especially in the middle rock wall damage and reduce the self-bearing capacity of surrounding rock. Through detecting and analyzing by the geological radar of the excavated red layer soft rock tunnel surrounding rock found that the middle rock wall loose circle thickness of the tunnel reaches to 1.8 m, the vault and sidewall loose circle thickness is about 1.2 m. Through selection of rational strengthening measures and blasting design scheme to improve drilling parameters and methods, as far as possible to protect the integrity and self-bearing capacity of the surrounding rock, the deformation and vibration of the tunnel would be controlled in reasonable limits and ensure the safety of tunnel construction.

  20. Water Tunnel Facility

    Data.gov (United States)

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

  1. Scanning tunneling spectroscopic studies of superconducting NbN single crystal thin films at 4.2 K

    International Nuclear Information System (INIS)

    Kashiwaya, S.; Koyanagi, M.; Matsuda, M.; Shoji, A.; Shibata, H.

    1991-01-01

    This paper reports on a Low Temperature Scanning Tunneling Microscope (LTSTM) constructed to study the microscopic properties of superconductors. It has atomic resolution from room temperature to 4.2 K. Conductance spectra obtained between a Pt tip and a NbN thin film agreed well with theoretical curves based on the BCS theory

  2. Liquid phase epitaxy of abrupt junctions in InAs and studies of injection radiative tunneling processes

    International Nuclear Information System (INIS)

    Bull, D.J.

    1977-01-01

    The p-n junction in a InAs crystal, by liquid phase epitaxy is obtained. The processes of injection and tunneling radiative recombination by emitted radiation from active region of p-n junction for low injection current are studied. (M.C.K.) [pt

  3. Type 2 diabetes seems not to be a risk factor for the carpal tunnel syndrome : a case control study

    NARCIS (Netherlands)

    Hendriks, Steven H.; van Dijk, Peter R.; Groenier, Klaas H.; Houpt, Peter; Bilo, Henk J. G.; Kleefstra, Nanne

    2014-01-01

    BACKGROUND: Previous studies have shown that the carpal tunnel syndrome seems to occur more frequently in patients with diabetes mellitus and might be associated with the duration of diabetes mellitus, microvascular complications and degree of glycaemic control. Primary aim was to determine if type

  4. Hydrogen bond nature of ferroelectric material studied by X-ray and neutron diffraction. Electric dipole moment and proton tunneling

    International Nuclear Information System (INIS)

    Noda, Yukio; Kiyanagi, Ryoji; Mochida, Tomoyuki; Sugawara, Tadashi

    2006-01-01

    Hydrogen bond nature of MeHPLN and BrHPLN is studied using x-ray and neutron diffraction technique. We found that electric dipole moment of hydrogen atom plays an important role for the phase transition, and proton tunneling model is confirmed on this isolated hydrogen bond system. (author)

  5. Fuel use and metabolic response to endurance exercise : a wind tunnel study of a long-distance migrant shorebird

    NARCIS (Netherlands)

    Jenni-Eiermann, Susanne; Jenni, Lukas; Kvist, Anders; Lindström, Åke; Piersma, Theunis; Visser, G. Henk

    This study examines fuel use and metabolism in a group of long-distance migrating birds, red knots Calidris canutus (Scolopacidae), flying under controlled conditions in a wind tunnel for up to 10 h. Data are compared with values for resting birds fasting for the same time. Plasma levels of free

  6. A STUDY OF THE HELIOCENTRIC DEPENDENCE OF SHOCK STANDOFF DISTANCE AND GEOMETRY USING 2.5D MAGNETOHYDRODYNAMIC SIMULATIONS OF CORONAL MASS EJECTION DRIVEN SHOCKS

    International Nuclear Information System (INIS)

    Savani, N. P.; Shiota, D.; Kusano, K.; Vourlidas, A.; Lugaz, N.

    2012-01-01

    We perform four numerical magnetohydrodynamic simulations in 2.5 dimensions (2.5D) of fast coronal mass ejections (CMEs) and their associated shock fronts between 10 Rs and 300 Rs. We investigate the relative change in the shock standoff distance, Δ, as a fraction of the CME radial half-width, D OB (i.e., Δ/D OB ). Previous hydrodynamic studies have related the shock standoff distance for Earth's magnetosphere to the density compression ratio (DR; ρ u /ρ d ) measured across the bow shock. The DR coefficient, k dr , which is the proportionality constant between the relative standoff distance (Δ/D OB ) and the compression ratio, was semi-empirically estimated as 1.1. For CMEs, we show that this value varies linearly as a function of heliocentric distance and changes significantly for different radii of curvature of the CME's leading edge. We find that a value of 0.8 ± 0.1 is more appropriate for small heliocentric distances ( dr value increases linearly with heliocentric distance, such that k dr = 1.1 is most appropriate at a heliocentric distance of about 80 Rs. For terrestrial distances (215 Rs) we estimate k dr = 1.8 ± 0.3, which also indicates that the CME cross-sectional structure is generally more oblate than that of Earth's magnetosphere. These alterations to the proportionality coefficients may serve to improve investigations into the estimates of the magnetic field in the corona upstream of a CME as well as the aspect ratio of CMEs as measured in situ.

  7. Parametric study of non-relativistic electrostatic shocks and the structure of their transition layer

    Energy Technology Data Exchange (ETDEWEB)

    Dieckmann, M. E. [Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam (Germany); Department of Science and Technology, Linkoeping University, SE-60174 Norrkoeping (Sweden); Ahmed, H.; Sarri, G.; Doria, D.; Kourakis, I.; Borghesi, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom); Romagnani, L. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Pohl, M. [Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam (Germany); DESY, D-15738 Zeuthen (Germany)

    2013-04-15

    Nonrelativistic electrostatic unmagnetized shocks are frequently observed in laboratory plasmas and they are likely to exist in astrophysical plasmas. Their maximum speed, expressed in units of the ion acoustic speed far upstream of the shock, depends only on the electron-to-ion temperature ratio if binary collisions are absent. The formation and evolution of such shocks is examined here for a wide range of shock speeds with particle-in-cell simulations. The initial temperatures of the electrons and the 400 times heavier ions are equal. Shocks form on electron time scales at Mach numbers between 1.7 and 2.2. Shocks with Mach numbers up to 2.5 form after tens of inverse ion plasma frequencies. The density of the shock-reflected ion beam increases and the number of ions crossing the shock thus decreases with an increasing Mach number, causing a slower expansion of the downstream region in its rest frame. The interval occupied by this ion beam is on a positive potential relative to the far upstream. This potential pre-heats the electrons ahead of the shock even in the absence of beam instabilities and decouples the electron temperature in the foreshock ahead of the shock from the one in the far upstream plasma. The effective Mach number of the shock is reduced by this electron heating. This effect can potentially stabilize nonrelativistic electrostatic shocks moving as fast as supernova remnant shocks.

  8. Parametric study of non-relativistic electrostatic shocks and the structure of their transition layer

    International Nuclear Information System (INIS)

    Dieckmann, M. E.; Ahmed, H.; Sarri, G.; Doria, D.; Kourakis, I.; Borghesi, M.; Romagnani, L.; Pohl, M.

    2013-01-01

    Nonrelativistic electrostatic unmagnetized shocks are frequently observed in laboratory plasmas and they are likely to exist in astrophysical plasmas. Their maximum speed, expressed in units of the ion acoustic speed far upstream of the shock, depends only on the electron-to-ion temperature ratio if binary collisions are absent. The formation and evolution of such shocks is examined here for a wide range of shock speeds with particle-in-cell simulations. The initial temperatures of the electrons and the 400 times heavier ions are equal. Shocks form on electron time scales at Mach numbers between 1.7 and 2.2. Shocks with Mach numbers up to 2.5 form after tens of inverse ion plasma frequencies. The density of the shock-reflected ion beam increases and the number of ions crossing the shock thus decreases with an increasing Mach number, causing a slower expansion of the downstream region in its rest frame. The interval occupied by this ion beam is on a positive potential relative to the far upstream. This potential pre-heats the electrons ahead of the shock even in the absence of beam instabilities and decouples the electron temperature in the foreshock ahead of the shock from the one in the far upstream plasma. The effective Mach number of the shock is reduced by this electron heating. This effect can potentially stabilize nonrelativistic electrostatic shocks moving as fast as supernova remnant shocks.

  9. Study on the Traffic Air Pollution inside and outside a Road Tunnel in Shanghai, China

    Science.gov (United States)

    Zhou, Rui; Wang, Shanshan; Shi, Chanzhen; Wang, Wenxin; Zhao, Heng; Liu, Rui; Chen, Limin; Zhou, Bin

    2014-01-01

    To investigate the vehicle induced air pollution situations both inside and outside the tunnel, the field measurement of the pollutants concentrations and its diurnal variations was performed inside and outside the Xiangyin tunnel in Shanghai from 13:00 on April 24th to 13:00 on April 25th, 2013. The highest hourly average concentrations of pollutants were quantified that CO, NO, NO2 and NOX inside the tunnel were 13.223 mg/m3, 1.829 mg/m3, 0.291 mg/m3 and 3.029 mg/m3, respectively, while the lowest ones were 3.086 mg/m3, 0.344 mg/m3, 0.080 mg/m3 and 0.619 mg/m3. Moreover, the concentrations of pollutants were higher during the daytime, and lower at night, which is relevant to the traffic conditions inside the tunnel. Pollutants concentrations inside the tunnel were much higher than those outside the tunnel. Then in a case of slow wind, the effect of wind is much smaller than the impact of pollution sources. Additionally, the PM2.5 concentrations climbed to the peak sharply (468.45 µg/m3) during the morning rush hours. The concentrations of organic carbon (OC) and elemental carbon (EC) in PM2.5 inside the tunnel were 37.09–99.06 µg/m3 and 22.69–137.99 µg/m3, respectively. Besides, the OC/EC ratio ranged from 0.72 to 2.19 with an average value of 1.34. Compared with the results of other tunnel experiments in Guangzhou and Shenzhen, China, it could be inferred that the proportion of HDVs through the Xiangyin tunnel is relatively lower. PMID:25386920

  10. Tunneling progress on the Yucca Mountain Project

    International Nuclear Information System (INIS)

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

    1996-01-01

    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

  11. Constrained reaction volume approach for studying chemical kinetics behind reflected shock waves

    KAUST Repository

    Hanson, Ronald K.; Pang, Genny A.; Chakraborty, Sreyashi; Ren, Wei; Wang, Shengkai; Davidson, David Frank

    2013-01-01

    We report a constrained-reaction-volume strategy for conducting kinetics experiments behind reflected shock waves, achieved in the present work by staged filling in a shock tube. Using hydrogen-oxygen ignition experiments as an example, we

  12. Application of holographic interferometric studies of underwater shock-wave focusing to medicine

    Science.gov (United States)

    Takayama, Kazuyoshi; Nagoya, H.; Obara, Tetsuro; Kuwahara, M.

    1993-01-01

    Holographic interferometric flow visualization was successfully applied to underwater shock wave focusing and its application to extracorporeal shock wave lithotripsy (ESWL). Real time diffuse holograms revealed the shock wave focusing process in an ellipsoidal reflector made from PMMA and double exposure holographic interferometry also clarified quantitatively the shock focusing process. Disintegration of urinary tract stones and gallbladder stones was observed by high speed photogrammetry. Tissue damage associated with the ESWL treatment is discussed in some detail.

  13. FUNDAMENTAL TUNNELING PROCESSES IN MOSa SOLAR CELLS

    OpenAIRE

    Balberg , I.; Hanak , J.; Weakliem , H.; Gal , E.

    1981-01-01

    In previous studies of tunneling through a MOSa tunnel junction, where Sa was a-Si : H, it was shown that their characteristics resemble those of MOSc devices where Sc was crystalline silicon. In the present work we would like to report a demonstration of fundamental tunneling processes in such tunnel junctions. In particular, the transition from semiconductor controlled regime to tunneling controlled regime can be clearly distinguished. The present results represent one of the rare cases whe...

  14. Destructive quantum interference in spin tunneling problems

    OpenAIRE

    von Delft, Jan; Henley, Christopher L.

    1992-01-01

    In some spin tunneling problems, there are several different but symmetry-related tunneling paths that connect the same initial and final configurations. The topological phase factors of the corresponding tunneling amplitudes can lead to destructive interference between the different paths, so that the total tunneling amplitude is zero. In the study of tunneling between different ground state configurations of the Kagom\\'{e}-lattice quantum Heisenberg antiferromagnet, this occurs when the spi...

  15. Design of a facility for studying shock-cell noise on single and coaxial jets

    NARCIS (Netherlands)

    Guariglia, Daniel; Rubio Carpio, A.; Schram, Christophe

    2018-01-01

    Shock-cell noise occurs in aero-engines when the nozzle exhaust is supersonic and shock-cells are present in the jet. In commercial turbofan engines, at cruise, the secondary flow is often supersonic underexpanded, with the formation of annular shock-cells in the jet and consequent onset of

  16. Accuracy of a real-time continuous glucose monitoring system in children with septic shock: A pilot study

    OpenAIRE

    Prabhudesai, Sumant; Kanjani, Amruta; Bhagat, Isha; Ravikumar, Karnam G.; Ramachandran, Bala

    2015-01-01

    Aims: The aim of this prospective, observational study was to determine the accuracy of a real-time continuous glucose monitoring system (CGMS) in children with septic shock. Subjects and Methods: Children aged 30 days to 18 years admitted to the Pediatric Intensive Care Unit with septic shock were included. A real-time CGMS sensor was used to obtain interstitial glucose readings. CGMS readings were compared statistically with simultaneous laboratory blood glucose (BG). Results: Nineteen chil...

  17. New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal

    Directory of Open Access Journals (Sweden)

    Jinxing Lai

    2015-01-01

    Full Text Available In recent years, with the rapid growth of economy and sharp rise of motor vehicles in China, the pavement skid resistance in tunnel portals has become increasingly important in cold region. However, the deicing salt, snow removal with machine, and other antiskid measures adopted by highway maintenance division have many limitations. To improve the treatment effect, we proposed a new snow-melting approach employing electric heat tracing, in which heating cables are installed in the structural layer of road. Through the field experiment, laboratory experiment, and numerical investigation, structure type, heating power, and preheating time of the flexible pavement heating system in tunnel portal were systematically analyzed, and advantages of electric heat tracing technology in improving the pavement skid resistance in tunnel portal were also presented. Therefore, such new technology, which offers new snow-melting methods for tunnel portal, bridge, mountainous area, and large longitudinal slope in cold region, has promising prospect for extensive application.

  18. Factors influencing flow steadiness in laminar boundary layer shock interactions

    Science.gov (United States)

    Tumuklu, Ozgur; Levin, Deborah A.; Gimelshein, Sergey F.; Austin, Joanna M.

    2016-11-01

    The Direct Simulation Monte Carlo method has been used to model laminar shock wave boundary interactions of hypersonic flow over a 30/55-deg double-wedge and "tick-shaped" model configurations studied in the Hypervelocity Expansion Tube facility and T-ADFA free-piston shock tunnel, respectively. The impact of thermochemical effects on these interactions by changing the chemical composition from nitrogen to air as well as argon for a stagnation enthalpy of 8.0 MJ/kg flow are investigated using the 2-D wedge model. The simulations are found to reproduce many of the classic features related to Edney Type V strong shock interactions that include the attached, oblique shock formed over the first wedge, the detached bow shock from the second wedge, the separation zone, and the separation and reattachment shocks that cause complex features such as the triple point for both cases. However, results of a reacting air flow case indicate that the size of the separation length, and the movement of the triple point toward to the leading edge is much less than the nitrogen case.

  19. Ultrafast studies of shock-induced melting and phase transitions at LCLS

    Science.gov (United States)

    McMahon, Malcolm

    The study of shock-induced phase transitions, which is vital to the understanding of material response to rapid pressure changes, dates back to the 1950s, when Bankcroft et al reported a transition in iron. Since then, many transitions have been reported in a wide range of materials, but, due to the lack of sufficiently bright x-ray sources, the structural details of these new phases has been notably lacking. While the development of nanosecond in situ x-ray diffraction has meant that lattice-level studies of such phenomena have become possible, including studies of the phase transition reported 60 years ago in iron, the quality of the diffraction data from such studies is noticeably poorer than that obtained from statically-compressed samples on synchrotrons. The advent of x-ray free electron lasers (XFELs), such as the LCLS, has resulted in an unprecedented improvement in the quality of diffraction data that can be obtained from shock-compressed matter. Here I describe the results from three recent experiment at the LCLS that looked at the solid-solid and solid-liquid phase transitions in Sb, Bi and Sc using single 50 fs x-ray exposures. The results provide new insight into the structural changes and melting induced by shock compression. This work is supported by EPSRC under Grant No. EP/J017051/1. Use of the LCLS, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515.

  20. Enrollment into a time sensitive clinical study in the critical care setting: results from computerized septic shock sniffer implementation

    Science.gov (United States)

    Pieper, Matthew S; Pulido, Juan; Gajic, Ognjen

    2011-01-01

    Objective Recruitment of patients into time sensitive clinical trials in intensive care units (ICU) poses a significant challenge. Enrollment is limited by delayed recognition and late notification of research personnel. The objective of the present study was to evaluate the effectiveness of the implementation of electronic screening (septic shock sniffer) regarding enrollment into a time sensitive (24 h after onset) clinical study of echocardiography in severe sepsis and septic shock. Design We developed and tested a near-real time computerized alert system, the septic shock sniffer, based on established severe sepsis/septic shock diagnostic criteria. A sniffer scanned patients' data in the electronic medical records and notified the research coordinator on call through an institutional paging system of potentially eligible patients. Measurement The performance of the septic shock sniffer was assessed. Results The septic shock sniffer performed well with a positive predictive value of 34%. Electronic screening doubled enrollment, with 68 of 4460 ICU admissions enrolled during the 9 months after implementation versus 37 of 4149 ICU admissions before sniffer implementation (p<0.05). Efficiency was limited by study coordinator availability (not available at nights or weekends). Conclusions Automated electronic medical records screening improves the efficiency of enrollment and should be a routine tool for the recruitment of patients into time sensitive clinical trials in the ICU setting. PMID:21508415

  1. Enrollment into a time sensitive clinical study in the critical care setting: results from computerized septic shock sniffer implementation.

    Science.gov (United States)

    Herasevich, Vitaly; Pieper, Matthew S; Pulido, Juan; Gajic, Ognjen

    2011-01-01

    Recruitment of patients into time sensitive clinical trials in intensive care units (ICU) poses a significant challenge. Enrollment is limited by delayed recognition and late notification of research personnel. The objective of the present study was to evaluate the effectiveness of the implementation of electronic screening (septic shock sniffer) regarding enrollment into a time sensitive (24 h after onset) clinical study of echocardiography in severe sepsis and septic shock. We developed and tested a near-real time computerized alert system, the septic shock sniffer, based on established severe sepsis/septic shock diagnostic criteria. A sniffer scanned patients' data in the electronic medical records and notified the research coordinator on call through an institutional paging system of potentially eligible patients. The performance of the septic shock sniffer was assessed. The septic shock sniffer performed well with a positive predictive value of 34%. Electronic screening doubled enrollment, with 68 of 4460 ICU admissions enrolled during the 9 months after implementation versus 37 of 4149 ICU admissions before sniffer implementation (p<0.05). Efficiency was limited by study coordinator availability (not available at nights or weekends). Automated electronic medical records screening improves the efficiency of enrollment and should be a routine tool for the recruitment of patients into time sensitive clinical trials in the ICU setting.

  2. Study on Hot Gases Flow in Case of Fire in a Road Tunnel

    Directory of Open Access Journals (Sweden)

    Aleksander Król

    2018-03-01

    Full Text Available This paper presents the results of hot smoke tests, which were conducted in a real road tunnel. The tunnel is located within the expressway S69 in southern Poland between cities Żywiec and Zwardoń. Its common name is Laliki tunnel. It is a bidirectional non-urban tunnel. The length of the tunnel is 678 m and it is inclined by 4%. It is equipped with the longitudinal ventilation system. Two hot smoke tests have been carried out according to Australian Standard AS 4391-1999. Hot smoke tests corresponded to a Heat Release Rate (HRR equal to respectively 750 kW and 1500 kW. The fire source was located in the middle of the road lane imitating an initial phase of a car fire (respectively 150 m and 265 m from S portal. The temperature distribution was recorded during both tests using a set of fourteen thermocouples that were mounted at two stand poles located at the main axis of the tunnel on windward. The stand poles were placed at distances of 5 m and 10 m. The recorded data were applied to validate a numerical model, which was built and solved using Ansys Fluent. The calculated temperature distribution matched the measured values.

  3. Comparison of classical reaction paths and tunneling paths studied with the semiclassical instanton theory.

    Science.gov (United States)

    Meisner, Jan; Markmeyer, Max N; Bohner, Matthias U; Kästner, Johannes

    2017-08-30

    Atom tunneling in the hydrogen atom transfer reaction of the 2,4,6-tri-tert-butylphenyl radical to 3,5-di-tert-butylneophyl, which has a short but strongly curved reaction path, was investigated using instanton theory. We found the tunneling path to deviate qualitatively from the classical intrinsic reaction coordinate, the steepest-descent path in mass-weighted Cartesian coordinates. To perform that comparison, we implemented a new variant of the predictor-corrector algorithm for the calculation of the intrinsic reaction coordinate. We used the reaction force analysis method as a means to decompose the reaction barrier into structural and electronic components. Due to the narrow energy barrier, atom tunneling is important in the abovementioned reaction, even above room temperature. Our calculated rate constants between 350 K and 100 K agree well with experimental values. We found a H/D kinetic isotope effect of almost 10 6 at 100 K. Tunneling dominates the protium transfer below 400 K and the deuterium transfer below 300 K. We compared the lengths of the tunneling path and the classical path for the hydrogen atom transfer in the reaction HCl + Cl and quantified the corner cutting in this reaction. At low temperature, the tunneling path is about 40% shorter than the classical path.

  4. Strength of suture anchor versus transosseous tunnel in anatomic reconstruction of the ankle lateral ligaments: a biomechanical study.

    Science.gov (United States)

    Li, Hong-Yun; Hua, Ying-Hui; Wu, Zi-Ying; Chen, Bo; Chen, Shi-Yi

    2013-11-01

    The purpose of this study was to compare the biomechanical characteristics of fixation with 2-suture anchors versus transosseous tunnel fixation in anatomic reconstruction of the ankle lateral ligaments. Six matched pairs of human cadaveric ankles underwent anatomic lateral ankle reconstruction, and fixation of the graft on the talus was achieved with 2 suture anchors or a transosseous tunnel. Ankles for the transosseous tunnel group were chosen at random, with the paired contralateral ankles used for the 2-suture anchor group. Half of the peroneus brevis tendon was harvested as a graft. For each technique, one end of the tendon was secured to the original insertion point of the anterior talofibular ligament (ATFL) at the talus, whereas the other end was armed with 2 No. 5 nonabsorbable sutures (Ethicon, Somerville, NJ) and passed through the bone tunnel in the fibula. Biomechanical testing was performed by applying the force in line with the graft. Load to failure was determined at a displacement rate of 50 mm/min. The load-displacement curve, maximum load at failure (N), and stiffness (N/mm) were recorded and compared between the 2 techniques. There was no difference between constructs in the 2-suture anchor group and the transosseous tunnel group in terms of the ultimate load and stiffness (161.8 ± 47.6 N v 171.9 ± 76.0 N; P = .92; 4.59 ± 1.85 N/mm v 5.77 ± 1.98 N/mm; P = .35). Most constructs failed because of anchor pullout in the 2-suture anchor group (5 of 6) and fracture of the bony bridge in the transosseous tunnel group (6 of 6). The strength of fixation with suture anchors in anatomic reconstruction of the ankle lateral ligaments was equivalent to transosseous tunnel fixation as determined with biomechanical testing. However, this study did not prove that one is advantageous over the other. Both techniques showed excellent biomechanical results. Therefore, the 2-suture anchor fixation approach can be safely used in anatomic reconstruction of the

  5. Experimental study of micro dimple fabrication based on laser shock processing

    Science.gov (United States)

    Li, Kangmei; Hu, Yongxiang; Yao, Zhenqiang

    2013-06-01

    Micro-dimple array has been generally considered as a valuable texture for sliding surfaces. It can improve lubrication and reduce wear by acting as reservoirs of lubricants and grinding debris. Laser shock processing (LSP) is an innovative process which can not only improve fatigue, corrosion and wearing resistance but also shape metallic parts accurately. In this study, a new process for the fabrication of micro dimples based on LSP was proposed, which was named as laser peen texturing (LPT). Experiments were performed on 2024 aluminum alloy, Oxygen-Free High Conductivity (OFHC) copper and SUS304 stainless steel to study the effects of processing parameters of LPT on surface integrity of the specimen. Surface morphology, micro hardness and microstructure of the micro dimples were investigated under various laser power densities, laser spot diameters and repeated shock numbers. It was found that the depth of the micro dimples induced by LPT is strongly dependent on material properties. The diameter, depth as well as aspect ratio of micro dimples were increased with the laser power density and the repeated shock number under the conditions in this study. But when the laser spot diameter changed, the variation laws of the diameter, depth and aspect ratio of the dimple were different from each other. The results of micro hardness measurements suggested that LPT is beneficial for the improvement of the micro hardness beneath the dimple. Grain refinement was found significantly on 2024 aluminum alloy and OFHC copper but not clearly on SUS304 stainless steel. Both the hardening effect and the grain refinement have close relationship with the depth of the micro dimple.

  6. Hydrodynamic optical soliton tunneling

    Science.gov (United States)

    Sprenger, P.; Hoefer, M. A.; El, G. A.

    2018-03-01

    A notion of hydrodynamic optical soliton tunneling is introduced in which a dark soliton is incident upon an evolving, broad potential barrier that arises from an appropriate variation of the input signal. The barriers considered include smooth rarefaction waves and highly oscillatory dispersive shock waves. Both the soliton and the barrier satisfy the same one-dimensional defocusing nonlinear Schrödinger (NLS) equation, which admits a convenient dispersive hydrodynamic interpretation. Under the scale separation assumption of nonlinear wave (Whitham) modulation theory, the highly nontrivial nonlinear interaction between the soliton and the evolving hydrodynamic barrier is described in terms of self-similar, simple wave solutions to an asymptotic reduction of the Whitham-NLS partial differential equations. One of the Riemann invariants of the reduced modulation system determines the characteristics of a soliton interacting with a mean flow that results in soliton tunneling or trapping. Another Riemann invariant yields the tunneled soliton's phase shift due to hydrodynamic interaction. Soliton interaction with hydrodynamic barriers gives rise to effects that include reversal of the soliton propagation direction and spontaneous soliton cavitation, which further suggest possible methods of dark soliton control in optical fibers.

  7. Quantum tunneling with friction

    Science.gov (United States)

    Tokieda, M.; Hagino, K.

    2017-05-01

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

  8. Wind Tunnel Study on Flows over Various Two-dimensional Idealized Urban-liked Surfaces

    Science.gov (United States)

    Ho, Yat-Kiu; Liu, Chun-Ho

    2013-04-01

    Extensive human activities (e.g. increased traffic emissions) emit a wide range of pollutants resulting in poor urban area air quality. Unlike open, flat and homogenous rural terrain, urban surface is complicated by the presence of buildings, obstacles and narrow streets. The irregular urban surfaces thus form a random roughness that further modifies the near-surface flows and pollutant dispersion. In this study, a physical modelling approach is employed to commence a series of wind tunnel experiments to study the urban-area air pollution problems. The flow characteristics over different hypothetical urban roughness surfaces were studied in a wind tunnel in isothermal conditions. Preliminary experiments were conducted based on six types of idealized two-dimensional (2D) street canyon models with various building-height-to-street-width (aspect) ratios (ARs) 1, 1/2, 1/4, 1/8, 1/10 and 1/12. The main instrumentation is an in-house 90o X-hotwire anemometry. In each set of configuration, a sampling street canyon was selected near the end of the streamwise domain. Its roof level, i.e. the transverse between the mid points of the upstream and downstream buildings, was divided into eight segments. The measurements were then recorded on the mid-plane of the spannwise domain along the vertical profile (from building roof level to the ceiling of wind tunnel) of the eight segments. All the data acquisition processes were handled by the NI data acquisition modules, NI 9239 and CompactDAQ-9188 hardware. Velocity calculation was carried out in the post-processing stage on a digital computer. The two-component flow velocities and velocity fluctuations were calculated at each sampling points, therefore, for each model, a streamwise average of eight vertical profiles of mean velocity and velocity fluctuations was presented. A plot of air-exchange rate (ACH) against ARs was also presented in order to examine the ventilation performance of different tested models. Preliminary results

  9. Tunneling Spectroscopy Studies of Epitaxial Graphene on Silicon Carbide(0001) and Its Interfaces

    Science.gov (United States)

    Sandin, Andreas Axel Tomas

    A two dimensional network of sp2 bonded carbon atoms is defined as graphene. This novel material possesses remarkable electronic properties due to its unique band structure at the vicinity of the Fermi energy. The toughest challenge to bring use of graphene electronic properties in device geometries is that graphene is exceptionally sensitive to its electrical environment for integration into macroscopic system of electrical contacts and substrates. One of the most promising substrates for graphene is the polar surfaces of SiC for the reason it can be grown epitaxially by sublimating Si from the top-most SiC atomic layers. In this work, the interfaces of graphene grown on the Si-terminated polar surface SiC(0001) is studied in UHV using scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), low energy electron diffraction (LEED) and auger electron Spectroscopy (AES). STM is used image the graphene surface and interfaces with the capability of atomic resolution. LEED is used to study surface atomic reciprocal ordering and AES is used to determine surface atomic composition during the graphene formation. Interfacial layer (Buffer layer), Single layer graphene and bilayer graphene are identified electronically by means of probing the first member of the image potential derived state. This state is found by dZ/dV spectroscopy in the high energy unoccupied states and is exceptionally sensitive to electrostatic changes to the surface which is detected by energy shifts of image potential states (IPS). This sensitivity is utilized to probe the graphene screening of external electric fields by varying the electric field in the tunneling junction and addresses the fact that charged impurity scattering is likely to be crucial for epitaxial graphene on SiC(0001) when it comes to transport parameters. Shifts of IPS energy position has also been used verify work function changes for identification of several Sodium Intercalation structures of epitaxial

  10. Preliminary studies of tunnel interface response modeling using test data from underground storage facilities.

    Energy Technology Data Exchange (ETDEWEB)

    Sobolik, Steven Ronald; Bartel, Lewis Clark

    2010-11-01

    In attempting to detect and map out underground facilities, whether they be large-scale hardened deeply-buried targets (HDBT's) or small-scale tunnels for clandestine border or perimeter crossing, seismic imaging using reflections from the tunnel interface has been seen as one of the better ways to both detect and delineate tunnels from the surface. The large seismic impedance contrast at the tunnel/rock boundary should provide a strong, distinguishable seismic response, but in practice, such strong indicators are often lacking. One explanation for the lack of a good seismic reflection at such a strong contrast boundary is that the damage caused by the tunneling itself creates a zone of altered seismic properties that significantly changes the nature of this boundary. This report examines existing geomechanical data that define the extent of an excavation damage zone around underground tunnels, and the potential impact on rock properties such as P-wave and S-wave velocities. The data presented from this report are associated with sites used for the development of underground repositories for the disposal of radioactive waste; these sites have been excavated in volcanic tuff (Yucca Mountain) and granite (HRL in Sweden, URL in Canada). Using the data from Yucca Mountain, a numerical simulation effort was undertaken to evaluate the effects of the damage zone on seismic responses. Calculations were performed using the parallelized version of the time-domain finitedifference seismic wave propagation code developed in the Geophysics Department at Sandia National Laboratories. From these numerical simulations, the damage zone does not have a significant effect upon the tunnel response, either for a purely elastic case or an anelastic case. However, what was discovered is that the largest responses are not true reflections, but rather reradiated Stoneley waves generated as the air/earth interface of the tunnel. Because of this, data processed in the usual way may not

  11. Aeroelastic Uncertainty Quantification Studies Using the S4T Wind Tunnel Model

    Science.gov (United States)

    Nikbay, Melike; Heeg, Jennifer

    2017-01-01

    This paper originates from the joint efforts of an aeroelastic study team in the Applied Vehicle Technology Panel from NATO Science and Technology Organization, with the Task Group number AVT-191, titled "Application of Sensitivity Analysis and Uncertainty Quantification to Military Vehicle Design." We present aeroelastic uncertainty quantification studies using the SemiSpan Supersonic Transport wind tunnel model at the NASA Langley Research Center. The aeroelastic study team decided treat both structural and aerodynamic input parameters as uncertain and represent them as samples drawn from statistical distributions, propagating them through aeroelastic analysis frameworks. Uncertainty quantification processes require many function evaluations to asses the impact of variations in numerous parameters on the vehicle characteristics, rapidly increasing the computational time requirement relative to that required to assess a system deterministically. The increased computational time is particularly prohibitive if high-fidelity analyses are employed. As a remedy, the Istanbul Technical University team employed an Euler solver in an aeroelastic analysis framework, and implemented reduced order modeling with Polynomial Chaos Expansion and Proper Orthogonal Decomposition to perform the uncertainty propagation. The NASA team chose to reduce the prohibitive computational time by employing linear solution processes. The NASA team also focused on determining input sample distributions.

  12. Intradermal therapy (mesotherapy) for the treatment of acute pain in carpal tunnel syndrome: a preliminary study.

    Science.gov (United States)

    Conforti, Giorgio; Capone, Loredana; Corra, Stefano

    2014-01-01

    The carpal tunnel syndrome (CTS) is the most common cause of severe hand pain. In this study we treated acute pain in CTS patients by means of local intradermal injections of anti-inflammatory drugs (mesotherapy). In twenty-five patients (forty-five hands), CTS diagnosis was confirmed by clinical and neurophysiological examination prior to mesotherapy. A mixture containing lidocaine 10 mg, ketoprophen lysine-acetylsalycilate 80 mg, xantinol nicotinate 100 mg, cyanocobalamine 1,000 mcg plus injectable water was used. Sites of injection were three parallel lines above the transverse carpal ligament and two v-shaped lines, one at the base of the thenar eminence, and the other at the base of the hypothenar eminence. The day after the treatment, all but four patients reported a significant reduction in pain and paresthesias. After 12 months, 17 patients had a complete pain relief, eight patients reported recurrence of pain and sensory symptoms and four out of them underwent surgical treatment. With the obvious limits of a small-size open-label study, our results suggest that mesotherapy can temporary relieve pain and paresthesias in most CTS patients and in some cases its effect seems to be long-lasting. Further controlled studies are needed to confirm our preliminary findings and to compare mesotherapy to conventional approaches for the treatment of CTS.

  13. Scanning tunneling microscopy study of the possible topological surface states in BiTeCl

    International Nuclear Information System (INIS)

    Yan, Y J; Ren, M Q; Liu, X; Huang, Z C; Jiang, J; Fan, Q; Miao, J; Xie, B P; Zhang, T; Feng, D L; Xiang, F; Wang, X

    2015-01-01

    Recently, the non-centrosymmetric bismuth tellurohalides such as BiTeCl are being studied as possible candidates for topological insulators. While some photoemission studies showed that BiTeCl is an inversion asymmetric topological insulator, others showed that it is a normal semiconductor with Rashba splitting. Meanwhile, first-principle calculations have failed to confirm the existence of topological surface states in BiTeCl so far. Therefore, the topological nature of BiTeCl requires further investigation. Here we report a low-temperature scanning tunneling microscopy study on the surface states of BiTeCl single crystals. On the tellurium (Te) -terminated surfaces with relatively low defect density, evidence for topological surface states is observed in the quasi-particle interference patterns, both in the anisotropy of the scattering vectors and the fast decay of the interference near the step edges. Meanwhile, on the samples with much higher defect densities, we observed surface states that behave differently. Our results may help to resolve the current controversy on the topological nature of BiTeCl. (paper)

  14. Typical Underwater Tunnels in the Mainland of China and Related Tunneling Technologies

    Directory of Open Access Journals (Sweden)

    Kairong Hong

    2017-12-01

    Full Text Available In the past decades, many underwater tunnels have been constructed in the mainland of China, and great progress has been made in related tunneling technologies. This paper presents the history and state of the art of underwater tunnels in the mainland of China in terms of shield-bored tunnels, drill-and-blast tunnels, and immersed tunnels. Typical underwater tunnels of these types in the mainland of China are described, along with innovative technologies regarding comprehensive geological prediction, grouting-based consolidation, the design and construction of large cross-sectional tunnels with shallow cover in weak strata, cutting tool replacement under limited drainage and reduced pressure conditions, the detection and treatment of boulders, the construction of underwater tunnels in areas with high seismic intensity, and the treatment of serious sedimentation in a foundation channel of immersed tunnels. Some suggestions are made regarding the three potential great strait-crossing tunnels—the Qiongzhou Strait-Crossing Tunnel, Bohai Strait-Crossing Tunnel, and Taiwan Strait-Crossing Tunnel—and issues related to these great strait-crossing tunnels that need further study are proposed. Keywords: Underwater tunnel, Strait-crossing tunnel, Shield-bored tunnel, Immersed tunnel, Drill and blast

  15. Heat-shock responses in two leguminous plants: a comparative study.

    Science.gov (United States)

    Ortiz, C; Cardemil, L

    2001-08-01

    Relative growth rates, basal and acclimated thermotolerance, membrane damage, fluorescence emission, and relative levels of free and conjugated ubiquitin and HSP70 were compared after 2 h of treatment at different temperatures between Prosopis chilensis and Glycine max (soybean), cv. McCall, to evaluate if the thermotolerance of these two plants was related to levels of accumulation of heat shock proteins. Seedlings of P. chilensis germinated at 25 degrees C and at 35 degrees C and grown at temperatures above germination temperature showed higher relative growth than soybean seedlings treated under the same conditions. The lethal temperature of both species was 50 degrees C after germination at 25 degrees C. However, they were able to grow at 50 degrees C after germination at 35 degrees C. Membrane damage determinations in leaves showed that P. chilensis has an LT(50) 6 degrees C higher than that of soybean. There were no differences in the quantum yield of photosynthesis (F(v)/F(m)), between both plants when the temperatures were raised. P. chilensis showed higher relative levels of free ubiquitin, conjugated ubiquitin and HSP70 than soybean seedlings when the temperatures were raised. Time-course studies of accumulation of these proteins performed at 40 degrees C showed that the relative accumulation rates of ubiquitin, conjugated ubiquitin and HSP70 were higher in P. chilensis than in soybean. In both plants, free ubiquitin decreased during the first 5 min and increased after 30 min of heat shock, conjugated ubiquitin increased after 30 min and HSP70 began to increase dramatically after 20 min of heat shock. From these data it is concluded that P. chilensis is more tolerant to acute heat stress than soybean.

  16. Analysis of intraosseous samples in endotoxemic shock--an experimental study in the anaesthetised pig.

    Science.gov (United States)

    Strandberg, G; Larsson, A; Lipcsey, M; Berglund, L; Eriksson, M

    2014-03-01

    Intraosseous (IO) access is used in emergency situations to allow rapid initiation of treatment. IO access is also sometimes used for blood sampling, although data on accuracy of such sampling in critical illness are limited. There is also a potential risk that bone marrow fragments in IO samples may damage laboratory equipment. It is ethically questionable to perform a simultaneous comparison between IO and arterial/venous sampling in critically ill humans. We have, thus, studied the analytical performance of IO sampling in a porcine septic shock model using a cartridge-based analyser. Eight pigs with endotoxin-induced septic shock were sampled hourly for 6 h, and analysed for blood gases, acid base status, haemoglobin, glucose and lactate using point of care instruments. Samples were taken from three IO cannulae (tibia bilaterally, one with infusion, and humerus), one arterial and one venous. An interaction test was used to assess changes in agreement between methods over time. Bland–Altman plots were constructed to study bias between methods. There were, to a varying extent, differences between IO and arterial/venous levels for all studied variables, but agreement did not change significantly during the experiment. A general finding was a large dispersion of differences between methods. IO sample values should be treated with caution in this setting but may add useful information to the clinical picture. The tibia or humerus may be used for sampling. IO infusion decreases agreement, thus sampling during infusion should be avoided.

  17. A prospective study of carpal tunnel syndrome: workplace and individual risk factors

    Science.gov (United States)

    Burt, Susan; Deddens, James A; Crombie, Ken; Jin, Yan; Wurzelbacher, Steve; Ramsey, Jessica

    2015-01-01

    Objectives To quantify the risk for carpal tunnel syndrome (CTS) from workplace physical factors, particularly hand activity level and forceful exertion, while taking into account individual factors including age, gender, body mass index (BMI), and pre-existing medical conditions. Methods Three healthcare and manufacturing workplaces were selected for inclusion on the basis of range of exposure to hand activity level and forceful exertion represented by their jobs. Each study participants job tasks were observed and evaluated ’ onsite and videotaped for further analysis, including frequency and duration of exertion and postural deviation. Individual health assessment entailed electrodiagnostic testing of median and ulnar nerves, physical examination and questionnaires at baseline with annual follow-up for 2 years. Results The incidence of dominant hand CTS during the study was 5.11 per 100 person-years (29 cases). Adjusted HRs for dominant hand CTS were as follows: working with forceful exertion ≥20% but job strain. Conclusions Workplace and individual risk factors both contribute to the risk for CTS. Time spent in forceful exertion can be a greater risk for CTS than obesity if the job exposure is high. Preventive workplace efforts should target forceful exertions. PMID:23788614

  18. An experimental study of furan adsorption and decomposition on vicinal palladium surfaces using scanning tunneling microscopy

    Science.gov (United States)

    Loui, A.; Chiang, S.

    2018-04-01

    The intact adsorption and decomposition of furan (C4H4O) on vicinal palladium surfaces with (111)-oriented terraces has been studied by scanning tunneling microscopy (STM) over a range of temperatures. STM images at 225 K show that furan molecules lie flat and prefer to adsorb at upper step edges. At 225 K, furan molecules adsorbed on "narrow" terraces of 20 to 45 Å in width appear to diffuse more readily than those adsorbed on "wide" terraces of 160 to 220 Å. A distinct population of smaller features appears in STM images on "narrow" terraces at 288 K and on "wide" terraces at 415 K and is identified with the C3H3 decomposition product, agreeing with prior studies which demonstrated that furan dissociates on Pd(111) to yield carbon monoxide (CO) and a C3H3 moiety in the 280 to 320 K range. Based on our direct visualization of this reaction using STM, we propose a spatial mechanism in which adsorption of furan at upper step edges allows catalysis of the dissociation, followed by diffusion of the product to lower step edges.

  19. Wind tunnel study of a vertical axis wind turbine in a turbulent boundary layer flow

    Science.gov (United States)

    Rolin, Vincent; Porté-Agel, Fernando

    2015-04-01

    Vertical axis wind turbines (VAWTs) are in a relatively infant state of development when compared to their cousins the horizontal axis wind turbines. Very few studies have been carried out to characterize the wake flow behind VAWTs, and virtually none to observe the influence of the atmospheric boundary layer. Here we present results from an experiment carried out at the EPFL-WIRE boundary-layer wind tunnel and designed to study the interaction between a turbulent boundary layer flow and a VAWT. Specifically we use stereoscopic particle image velocimetry to observe and quantify the influence of the boundary layer flow on the wake generated by a VAWT, as well as the effect the VAWT has on the boundary layer flow profile downstream. We find that the wake behind the VAWT is strongly asymmetric, due to the varying aerodynamic forces on the blades as they change their position around the rotor. We also find that the wake adds strong turbulence levels to the flow, particularly on the periphery of the wake where vortices and strong velocity gradients are present. The boundary layer is also shown to cause greater momentum to be entrained downwards rather than upwards into the wake.

  20. Tibial and Femoral Tunnel Changes After ACL Reconstruction: A Prospective 2-Year Longitudinal MRI Study.

    Science.gov (United States)

    Weber, Alexander E; Delos, Demetris; Oltean, Hanna N; Vadasdi, Katherine; Cavanaugh, John; Potter, Hollis G; Rodeo, Scott A

    2015-05-01

    Tunnel widening after anterior cruciate ligament reconstruction (ACL-R) is a well-accepted and frequent phenomenon, yet little is known regarding its origin or natural history. To prospectively evaluate the cross-sectional area (CSA) changes in tibial and femoral bone tunnels after ACL-R with serial MRI. Case series; Level of evidence, 4. Patients underwent arthroscopic ACL-R with the same surgeon, surgical technique, and rehabilitation protocol. Each patient underwent preoperative dual-energy x-ray absorptiometry and clinical evaluation, as well as postoperative time zero MRI followed by subsequent MRI and clinical examination, including functional and subjective outcome tests, at 6, 12, 24, 52, and 104 weeks. Tibial and femoral tunnel CSA was measured on each MRI at tunnel aperture (ttA and ftA), midsection (ttM and ftM), and exit (ttE and ftE). Logistic regression modeling was used to examine the predictive value of demographic data and preoperative bone quality (as measured by dual-energy x-ray absorptiometry) on functional outcome scores, manual and instrumented laxity measurements, and changes in tunnel area over time. Eighteen patients (including 12 men), mean age 35.5±8.7 years, underwent ACL-R. There was significant tunnel expansion at ttA and ftA sites 6 weeks postoperatively (P=.024 and .0045, respectively). Expansion continued for 24 weeks, with progressive tunnel narrowing thereafter. Average ttA CSA was significantly larger than ftA CSA at all times. The ttM significantly expanded after 6 weeks (P=.06); continued expansion to week 12 was followed by 21 months of reduction in tunnel diameter. The ftM and both ttE and ftE sites decreased in CSA over the 2 years. Median Lysholm and International Knee Documentation Committee scores significantly improved at final follow-up (P=.0083 and 1 year from time of injury) predicted increased tunnel widening and accelerated expansion in CSA (Pclinical outcome. Younger age, male sex, and delay from injury to ACL

  1. Relationship of Interplanetary Shock Micro and Macro Characteristics: A Wind Study

    Science.gov (United States)

    Szabo, Adam; Koval, A

    2008-01-01

    The non-linear least squared MHD fitting technique of Szabo 11 9941 has been recently further refined to provide realistic confidence regions for interplanetary shock normal directions and speeds. Analyzing Wind observed interplanetary shocks from 1995 to 200 1, macro characteristics such as shock strength, Theta Bn and Mach numbers can be compared to the details of shock micro or kinetic structures. The now commonly available very high time resolution (1 1 or 22 vectors/sec) Wind magnetic field data allows the precise characterization of shock kinetic structures, such as the size of the foot, ramp, overshoot and the duration of damped oscillations on either side of the shock. Detailed comparison of the shock micro and macro characteristics will be given. This enables the elucidation of shock kinetic features, relevant for particle energization processes, for observations where high time resolution data is not available. Moreover, establishing a quantitative relationship between the shock micro and macro structures will improve the confidence level of shock fitting techniques during disturbed solar wind conditions.

  2. Mortality and risk of cardiac complications among immediate survivors of accidental electric shock: a Danish nationwide cohort study.

    Science.gov (United States)

    Hansen, Steen Møller; Riahi, Sam; Hjortshøj, Søren; Mortensen, Rikke; Køber, Lars; Søgaard, Peter; Torp-Pedersen, Christian

    2017-08-28

    Exposure to electric shock has been associated with an increased risk of developing delayed cardiac arrhythmias and cardiac diseases. We examined whether electric shock patients have an increased risk of developing cardiac disease, cardiac arrhythmias or death compared with the general Danish population. Matched cohort study. A nationwide study in Denmark from 1994 to 2011. We identified 11 462 Danish patients who visited an emergency ward or were admitted to a hospital due to electric shock from 1994 to 2011. Each patient was matched for age and sex with five random controls from the Danish population. Mortality, cardiac procedures and cardiac diseases following electric shock. A total of 7390 electric shock patients were seen at an emergency ward and 4072 electric shock patients were admitted to a hospital. The median patient age was 28.6 years (Q1-Q3, 21.3-37.7) for the emergency ward patients and 26.4 years (Q1-Q3, 18.3-37.4) for admitted patients. In both groups, most patients were male (74.0% and 76.8%). Few of the electric shock patients had a record of cardiovascular disease at baseline (364/11 462, 3.2%). The 5-year cumulative incidence of death was 0.47% (95% CI 0.29% to 0.65%) for emergency ward patients and 1.04% (95% CI 0.71% to 1.37%) for admitted patients. No difference in 5-year survival was observed compared with matched controls (emergency ward, p=0.10; admitted patients, p=0.80). Fewer than four patients received a pacemaker within 30 days. This nationwide study did not demonstrate an increase in mortality among patients seen at hospitals after accidental electric shock compared with a background population. Cardiac procedures and diseases following electric shock were very rare. We suggest that nearly all patients can be discharged safely from the emergency room after electric shock without further observation. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial

  3. Study to optimize a disposal tunnel layout taking into account heterogeneous characteristics of the geological environment

    International Nuclear Information System (INIS)

    Suyama, Yasuhiro; Toida, Masaru; Yanagizawa, Koichi

    2007-01-01

    The geological environment has spatially heterogeneous characteristics with varied host rock types, fractures and so on. In this case the generic disposal tunnel layout, which has been designed by JNC, is not the most suitable for HLW disposal in Japan. The existence of spatially heterogeneous characteristics means that in the repository region there exist sub-regions that are more favorable from the perspective of long-term safety and ones that are less favorable. In order that the spatially heterogeneous environment itself may be utilized most effectively as an NBS, an alternative design of disposal tunnel layout is required. Focusing on the geological environment with spatially heterogeneous characteristics, the authors have developed an alternative design of disposal tunnel layout. The alternative design adopts an optimization approach using a 'variable disposal tunnel layout'. The optimization approach minimizes the number of locations where major water conducting fractures are intersected, and maximizes the number of emplacement locations for waste packages. This paper will outline the variable disposal tunnel layout and its applicability. (author)

  4. Spin-Polarized Scanning Tunneling Microscope for Atomic-Scale Studies of Spin Transport, Spin Relaxation, and Magnetism in Graphene

    Science.gov (United States)

    2017-11-09

    Polarized Scanning Tunneling Microscope for Atomic-Scale Studies of Spin Transport, Spin Relaxation, and Magnetism in Graphene Report Term: 0-Other Email ...Principal: Y Name: Jay A Gupta Email : gupta.208@osu.edu Name: Roland K Kawakami Email : kawakami.15@osu.edu RPPR Final Report as of 13-Nov-2017...studies on films and devices. Optimization of the Cr tip will be the next important step to establish this technique. We are writing up these early

  5. Mechanical and thermo-mechanical analyses of the tapered plug for plugging of deposition tunnels. A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Faelth, Billy (Clay Technology AB, Lund (Sweden)); Gatter, Patrik (Vattenfall Power Consultant AB, Stockholm (Sweden))

    2009-09-15

    This report presents results from a study that was carried out in order to examine the applicability of the tapered plug concept for plugging of deposition tunnels in the deep repository for spent nuclear fuel. The report presents results from mechanical and thermo-mechanical models of the tapered plug. The models were analyzed with 3DEC. The models included a portion of a deposition tunnel and its intersection with a main tunnel. In the deposition tunnel, a tapered concrete plug was installed. The plug was subjected to the combined load from the swelling backfill material and from pore pressure inside the deposition tunnel. The thermo-mechanical effects due to the heat generation in the spent fuel were also included in the analyses. Generic material parameter values for the concrete were used. The following items were studied: - Stresses and displacements in the plug. - Shear stresses and shear displacements in the rock-concrete interface. - Stress additions in the rock due to the loads. The sensitivity of the results to changes of constitutive models, to changes of the plug geometry and to pore water pressure in the rock-concrete interface was examined. The results indicate that the displacements in the plug will be within reasonable ranges but the stresses may locally be high enough that they exceed acceptable levels. However, they can be reduced by choice of advantageous plug geometry and by having a good rock-concrete bond. The results also show that the stress additions in the rock due to the thermal load may yield stresses that locally exceed the spalling strength of the rock. At most locations, however, the rock stresses will amount at lower levels. It was concluded that, with choice of an appropriate design, the tapered plug seems to be an applicable concept for plugging of deposition tunnels. It was also concluded that further studies of the tapered plug concept should use material properties parameter values for low-pH concrete. Further, they should also

  6. Braze alloy process and strength characterization studies for 18 nickel grade 200 maraging steel with application to wind tunnel models

    Science.gov (United States)

    Bradshaw, James F.; Sandefur, Paul G., Jr.; Young, Clarence P., Jr.

    1991-01-01

    A comprehensive study of braze alloy selection process and strength characterization with application to wind tunnel models is presented. The applications for this study include the installation of stainless steel pressure tubing in model airfoil sections make of 18 Ni 200 grade maraging steel and the joining of wing structural components by brazing. Acceptable braze alloys for these applications are identified along with process, thermal braze cycle data, and thermal management procedures. Shear specimens are used to evaluate comparative shear strength properties for the various alloys at both room and cryogenic (-300 F) temperatures and include the effects of electroless nickel plating. Nickel plating was found to significantly enhance both the wetability and strength properties for the various braze alloys studied. The data are provided for use in selecting braze alloys for use with 18 Ni grade 200 steel in the design of wind tunnel models to be tested in an ambient or cryogenic environment.

  7. A Wind Tunnel Study on the Mars Pathfinder (MPF) Lander Descent Pressure Sensor

    Science.gov (United States)

    Soriano, J. Francisco; Coquilla, Rachael V.; Wilson, Gregory R.; Seiff, Alvin; Rivell, Tomas

    2001-01-01

    The primary focus of this study was to determine the accuracy of the Mars Pathfinder lander local pressure readings in accordance with the actual ambient atmospheric pressures of Mars during parachute descent. In order to obtain good measurements, the plane of the lander pressure sensor opening should ideally be situated so that it is parallel to the freestream. However, due to two unfavorable conditions, the sensor was positioned in locations where correction factors are required. One of these disadvantages is due to the fact that the parachute attachment point rotated the lander's center of gravity forcing the location of the pressure sensor opening to be off tangent to the freestream. The second and most troublesome factor was that the lander descends with slight oscillations that could vary the amplitude of the sensor readings. In order to accurately map the correction factors required at each sensor position, an experiment simulating the lander descent was conducted in the Martian Surface Wind Tunnel at NASA Ames Research Center. Using a 115 scale model at Earth ambient pressures, the test settings provided the necessary Reynolds number conditions in which the actual lander was possibly subjected to during the descent. In the analysis and results of this experiment, the readings from the lander sensor were converted to the form of pressure coefficients. With a contour map of pressure coefficients at each lander oscillatory position, this report will provide a guideline to determine the correction factors required for the Mars Pathfinder lander descent pressure sensor readings.

  8. Initial Studies of Low Temperature Ablation in a Helium Hypersonic Wind Tunnel. Draft

    Energy Technology Data Exchange (ETDEWEB)

    Kohlman, D. L.; Elias, L.; Orlik-Ruckemann, K.

    1969-06-15

    A study of the feasibility of investigating the effects of ablation in a helium hypersonic wind tunnel was performed. Exploratory experiments were carried out at Mach 16.4 and at 600 psi stagnation pressure using (a) metal models at room temperature, (b) models with copper inserts, cooled to -140 deg C, and (c) models with carbon dioxide inserts. All models were flat plates at zero incidence, with a sharp leading edge in front of the insert. Surface temperature, surface recession rates and pitot pressure profiles were determined at several longitudinal stations. Suitable model fabrication and experimental techniques have been developed. A simple theoretical method of predicting recession rates and surface temperatures has been proposed. It has been demonstrated that the ablation of carbon dioxide into an unheated Mach 16.4 helium flow at 600 psi stagnation pressure is significant enough to result in measurable flat plate recession rates and measurable changes in pitot pressure profiles. In addition, it has been shown that it is possible to distinguish between the effects on pitot pressure of reduction in surface temperature and of mass addition through sublimation of carbon dioxide. It was also found that the first order theoretical analysis predicts proper trends and correct approximate magnitude of sublimation rates.

  9. Study of a high critical temperature superconductor through Josephson effect and tunnel spectroscopy

    International Nuclear Information System (INIS)

    Grison, X.

    2000-11-01

    This work, mainly experimental, is dedicated to the study of the Josephson effect and the tunnel spectroscopy of superconducting films. Thin films of YBa 2 Cu 3 O 7-δ oriented towards [0,0,1], [1,0,3], [1,1,0] or [1,0,0] axis have been made. The results concerning the [0,0,1] orientation are consistent with an order parameter having a d(x 2 -y 2 ) symmetry but with a small component of s symmetry due to the orthorombicity of YBa 2 Cu 3 O 7δ . The results concerning the [1,1,0] orientation show the existence (near (1,1,0)-type surfaces) of an order parameter whose symmetry is d(x 2 -y 2 ) ± i*s or more likely d(x 2 - y 2 ) ± i*d(xy). The latter term implies the breaking of the time reversing symmetry. The i*d(xy) component is responsible for the Josephson coupling along the [1,1,0] axis, which means that the coupling is not or is little carried by the Andreev bound states contrarily to recent predictions. It is also shown that Josephson junctions can be fabricated by using ion irradiation. (A.C.)

  10. Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

    Directory of Open Access Journals (Sweden)

    Thomas König

    2011-01-01

    Full Text Available Surfaces of thin oxide films were investigated by means of a dual mode NC-AFM/STM. Apart from imaging the surface termination by NC-AFM with atomic resolution, point defects in magnesium oxide on Ag(001 and line defects in aluminum oxide on NiAl(110, respectively, were thoroughly studied. The contact potential was determined by Kelvin probe force microscopy (KPFM and the electronic structure by scanning tunneling spectroscopy (STS. On magnesium oxide, different color centers, i.e., F0, F+, F2+ and divacancies, have different effects on the contact potential. These differences enabled classification and unambiguous differentiation by KPFM. True atomic resolution shows the topography at line defects in aluminum oxide. At these domain boundaries, STS and KPFM verify F2+-like centers, which have been predicted by density functional theory calculations. Thus, by determining the contact potential and the electronic structure with a spatial resolution in the nanometer range, NC-AFM and STM can be successfully applied on thin oxide films beyond imaging the topography of the surface atoms.

  11. A flow visualization study of spore release using a wind tunnel-mounted laser light sheet

    International Nuclear Information System (INIS)

    Davis, J.M.; Eisner, A.D.; Wiener, R.W.; Main, C.E.

    1997-01-01

    A phase Doppler anemometry system in combination with a laser light sheet was used in a low-speed recirculating wind tunnel to examine the flow field around an individual leaf. Turbulence similar to that encountered near the surface of the earth in a neutral stability boundary layer was generated using a grid at the upwind end of the wind tunnel test section. Individual healthy and diseased plant leaves were introduced into the tunnel with the leaf tip pointing downwind. The Mie-scattered radiation from the spores departing the diseased leaf was captured on videotape. Image processing software was used to enhance the visual quality of the individual frames from the videotape and to make spore velocity calculations. Three main vortex regions around the leaf were identified. The importance of these regions to the separation of the spores from the leaf surface and their subsequent downwind movement was analyzed

  12. Studies of proximity-effect and tunneling in YBCO/metal layered films

    Energy Technology Data Exchange (ETDEWEB)

    Greene, L.H.; Barner, J.B.; Feldmann, W.L.; Farrow, L.A.; Miceli, P.F.; Ramesh, R.; Wilkens, B.J.; Bagley, B.G.; Tarascon, J.M.; Wernick, J.H. (Bellcore, Red Bank, NJ (USA)); Giroud, M. (CRTBT-CNRS, Grenoble (France)); Rowell, J.M. (Conductus, Sunnyvale, CA (USA))

    1989-12-01

    The short coherence length of the high-Tc superconductors, coupled with their tendency to form non-superconducting surface layers, accounts for the difficulty in achieving good tunnel junctions. A proximity layer of a longer coherence length normal metal (N) is expected to ''draw out'' Cooper pairs. Our goal is to fabricate reproducible, planar tunnel junctions of SNIS layered structures for proximity tunneling spectroscopy. Such structures of YBCO/N/I/Pb and SNS structures of YBCO/N/Pb indicate that the normal metal produces a low resistance contact to the YBCO surface with a supercurrent observed in the SNS. The insulating barrier in the SNIS is reproducible, insulating and continuous: A sharp Pb gap and phonons from the counter-electrode are routinely observed. (orig.).

  13. Studies of proximity-effect and tunneling in YBCO/metal layered films

    International Nuclear Information System (INIS)

    Greene, L.H.; Barner, J.B.; Feldmann, W.L.; Farrow, L.A.; Miceli, P.F.; Ramesh, R.; Wilkens, B.J.; Bagley, B.G.; Tarascon, J.M.; Wernick, J.H.; Giroud, M.; Rowell, J.M.

    1989-01-01

    The short coherence length of the high-T c superconductors, coupled with their tendency to form non-superconducting surface layers, accounts for the difficulty in achieving good tunnel junctions. A proximity layer of a longer coherence length normal metal (N) is expected to draw out Cooper pairs. The authors' goal is to fabricate reproducible, planar tunnel junctions of SNIS layered structures for proximity tunneling spectroscopy. They discuss how such structures of YBCO/N/I/Pb and SNS structures of YBCO/N/Pb indicate that the normal metal produces a low resistance contact to the YBCO surface with a supercurrent observed in the SNS. The insulating barrier in the SNIS is reproducible, insulating and continuous: A sharp Pb gap and phonons from the counter-electrode are routinely observed

  14. CURRENT ASSET TUNNELING AND FIRM PERFORMANCE IN AN EMERGING MARKET

    OpenAIRE

    Ratna Candra Sari; Zaki Baridwan

    2014-01-01

    This study examines the effect of current asset tunneling on firm performance from the emerging market perspective. Although tunneling activities is a common practices by businesses especially in Indonesia, there exist obstacles in the measurement of tunneling activity because it is difficult to proof the existence of such practices. In this study, we measure tunneling by using accounts receivables and develop tunneling detection criteria. In addition, this study examines the effect of tunnel...

  15. STUDI KOMPUTASI BERBASIS DFT TERHADAP FENOMENA QUANTUM TUNNELING DALAM ISOMERISASI METILHIDROKSIKARBENA

    Directory of Open Access Journals (Sweden)

    Jumaidil Awal

    2016-01-01

    Full Text Available Density functional theory-based methods have been applied to predict the most possible one among the isomerizations of methylhydroxycarbene considering the probability of hydrogen tunneling occurrence. B3LYP/6-31+G(d,p and M08-SO/6-31+G(d,p methods were applied in all computations using GAMESS-US software. There were three steps of computation in this research. First, electronic structure computations of both equilibrium and transition compounds involved in all isomerization alternatives in order to obtain the optimum structures of the compounds. Second, vibrational computations of optimum transition structures to ensure that each of the respective structures is well on its potential energy surface. Third, tunneling analysis accomplished by intrinsic reaction coordinate (IRC computatuins for all isomerization alternatives followed by tunneling probabilitycalculation using the Wentzel-Kramers-Brillouin (WKB formula for methylhydroxycarbene isomerizations. The result of this research showed that the DFT methods successfully produced the optimum structure of each compound. Both DFT methods also successfully mapped all the intrinsic reaction coordinates. B3LYP/6-31+G(d,p method gave tunneling probabilities of 3.55 x 10-19 for the isomerization into acetaldehyde and 3.30 x 10-20 for that into vinyl alcohol. While M08-SO/6-31+G(d,p method gave tunneling probabilities of 2.38 x 10-23 for the isomerization into acetaldehyde and 4.79 x 10-23 for that into vinyl alcohol. Keywords: DFT, methylhydroxycarbene, hydrogen tunneling, isomerization

  16. Tracheal reconstruction by re-inforced Gore-Tex in esophageal submuscular tunneling: An experimental study

    Directory of Open Access Journals (Sweden)

    Hodjati Hossein

    2011-01-01

    Full Text Available Background: Tracheal reconstructions are aimed at rearranging or replacing parts of the tracheal tissue by different techniques. Here we introduce a new technique for tracheal reconstruction. Methods: In 10 adult dogs, after intubation with an endotracheal tube, a segment of trachea including seven tracheal rings was resected circumferentially. A submuscular tunnel was induced between mucosal and muscular layers of the adjacent esophagus lying right next to the trachea. The esophageal submuscular tunnel starts and ends exactly at the level of distal and proximal ends of tracheal resection, respectively. Inforced Gore-Tex passed through the esophageal submuscular tunnel the distal segment of trachea and end-to-end anastomosis were made between distal ends of Gore-Tex and trachea, then endotracheal tube removed and the same procedure was made for proximal ends of Gore-Tex and trachea. Afterward, the proximal and distal ends of the esophageal tunnel were approximated to proximal and distal tracheal parts over the anastomosis. Results: All dogs, except one due to anesthetic problem, survived and tolerated the operation; the first two dogs experienced postoperative fever, aspiration pneumonia, and died due to tracheoesophageal fistula. All survived animals were eating and barking well. We started to scarify dogs at least 6 and 12 weeks after operation for microscopy and pathologic examination. The Gore-Texes were patent and supported externally with fibrous connective tissue in esophageal tunneling, with in growth of respiratory epithelium on inner surfaces. Conclusion: Air tightness, good re-epithelialization, and relatively no limitation of esophageal length and no risk of luminal collapse are advantages of tracheal reconstruction by submuscular esophageal tunneling. This new method is worthy of further investigation, as it is technically feasible and easy to implement.

  17. Detailed study of electron plasma waves upstream of the earth's bow shock

    International Nuclear Information System (INIS)

    Etcheto, J.; Faucheux, M.

    1984-01-01

    A detailed study of electron plasma waves observed upstream of the earth's bow shock and of their relationships to the position of the satellite in the foreshock and to the electron measurements has been carried out. The wave characteristics depend on the position in the electron foreshock: a narrow-bnd (a few percent) and intense (a few millivolts per meter) noise is observed at the plasma frequency at the edge of the foreshock while the spectrum widens (Δf/fapprox. =0.3) at the same time as the power decreases (hundreds of microvolts per meter) deeper (a few earth radii) inside the foreshock. Signals below the plasma frequency are also observed. These waves are polarized along the magnetic field, with long wavelengths below and at the plasma frequency and short wavelengths above it. They appear as short bursts, the duration of which depends on the frequency: longer close to the plasma frequency (50 ms), they shorten with increasing separation from the plasma frequency, the usual duration being 15 ms. While the correlation of the wave characteristics with the reflected electrons is good as the satellite moves inside the foreshock, no evolution is found with the distance to the bow shock, neither for the noise nor for the particles. These results are discussed in the frame of various mechanisms which have been proposed to explain these upstream waves but no satisfactory agreement is found with any of them

  18. Parametric Study of Swept Impinging Oblique Shock/Boundary Layer Interactions

    Science.gov (United States)

    Doehrmann, Adam; Threadgill, James; Little, Jesse

    2017-11-01

    Modern high-speed vehicles have increasingly complex 3D geometries featuring: surface curvature, variable aspect ratio inlet ducts and swept bodies. Such distortion to the flow field necessitates a further understanding of swept 3D Shock/Boundary Layer Interactions (SBLIs), where various regimes of spanwise interaction development have been observed. A parametric experimental study of swept oblique impinging SBLIs has been conducted comparing cylindrical and conical interaction structures to that of swept compression ramps in previous work. This investigation examines five shock generators with 2D deflection of θ = 12 .5° and varying degrees of sweep (ψ = 10 .0° , 15 .0° , 22 .5° , 30 .0° , 40 .0°), with an incoming turbulent flow at Mach 2.3 and 3.0. Parametric characterization of surface oil-flow visualizations has shown that the inception length of the interaction follows a similar trend to that seen in swept compression ramps as sweep is varied, namely that it increases as sweep approaches a critical angle. However, this criteria disagrees with direct observations of separation and reattachment angles. Similarities in mean pressures profiles have also been assessed and analyzed with respect to the onset of a cylindrical/conical interaction. Supported by the Air Force Office of Scientific Research (FA9550-15-1-0430).

  19. Serum Procalcitonin and Peripheral Venous Lactate for Predicting Dengue Shock and/or Organ Failure: A Prospective Observational Study.

    Directory of Open Access Journals (Sweden)

    Vipa Thanachartwet

    2016-08-01

    Full Text Available Currently, there are no biomarkers that can predict the incidence of dengue shock and/or organ failure, although the early identification of risk factors is important in determining appropriate management to reduce mortality. Therefore, we sought to determine the factors associated with dengue shock and/or organ failure and to evaluate the prognostic value of serum procalcitonin (PCT and peripheral venous lactate (PVL levels as biomarkers of dengue shock and/or organ failure.A prospective observational study was conducted among adults hospitalized for confirmed viral dengue infection at the Hospital for Tropical Diseases in Bangkok, Thailand between October 2013 and July 2015. Data, including baseline characteristics, clinical parameters, laboratory findings, serum PCT and PVL levels, management, and outcomes, were recorded on pre-defined case report forms. Of 160 patients with dengue, 128 (80.0% patients had dengue without shock or organ failure, whereas 32 (20.0% patients developed dengue with shock and/or organ failure. Using a stepwise multivariate logistic regression analysis, PCT ≥0.7 ng/mL (odds ratio [OR]: 4.80; 95% confidence interval [CI]: 1.60-14.45; p = 0.005 and PVL ≥2.5 mmol/L (OR: 27.99, 95% CI: 8.47-92.53; p <0.001 were independently associated with dengue shock and/or organ failure. A combination of PCT ≥0.7 ng/mL and PVL ≥2.5 mmol/L provided good prognostic value for predicting dengue shock and/or organ failure, with an area under the receiver operating characteristics curve of 0.83 (95% CI: 0.74-0.92, a sensitivity of 81.2% (95% CI: 63.6-92.8%, and a specificity of 84.4% (95% CI: 76.9-90.2%. Dengue shock patients with non-clearance of PCT and PVL expired during hospitalization.PCT ≥0.7 ng/mL and PVL ≥2.5 mmol/L were independently associated with dengue shock and/or organ failure. The combination of PCT and PVL levels could be used as prognostic biomarkers for the prediction of dengue shock and/or organ failure.

  20. Micro-Ramp Flow Control for Oblique Shock Interactions: Comparisons of Computational and Experimental Data

    Science.gov (United States)

    Hirt, Stephanie M.; Reich, David B.; O'Connor, Michael B.

    2012-01-01

    Computational fluid dynamics was used to study the effectiveness of micro-ramp vortex generators to control oblique shock boundary layer interactions. Simulations were based on experiments previously conducted in the 15- by 15-cm supersonic wind tunnel at the NASA Glenn Research Center. Four micro-ramp geometries were tested at Mach 2.0 varying the height, chord length, and spanwise spacing between micro-ramps. The overall flow field was examined. Additionally, key parameters such as boundary-layer displacement thickness, momentum thickness and incompressible shape factor were also examined. The computational results predicted the effects of the microramps well, including the trends for the impact that the devices had on the shock boundary layer interaction. However, computing the shock boundary layer interaction itself proved to be problematic since the calculations predicted more pronounced adverse effects on the boundary layer due to the shock than were seen in the experiment.

  1. Conductance of single atoms and molecules studied with a scanning tunnelling microscope

    International Nuclear Information System (INIS)

    Neel, N; Kroeger, J; Limot, L; Berndt, R

    2007-01-01

    The conductance of single atoms and molecules is investigated with a low-temperature scanning tunnelling microscope. In a controlled and reproducible way, clean Ag(111) surfaces, individual silver atoms on Ag(111) as well as individual C 60 molecules adsorbed on Cu(100) are contacted with the tip of the microscope. Upon contact the conductance changes discontinuously in the case of the tip-surface junction while the tip-atom and tip-molecule junctions exhibit a continuous transition from the tunnelling to the contact regime

  2. Rotational barriers in ammonium hexachlorometallates as studied by NMR, tunneling spectroscopy and ab initio calculations

    DEFF Research Database (Denmark)

    Birczynski, A.; Lalowicz, Z.T.; Lodziana, Zbigniew

    2004-01-01

    Ammonium hexachlorometallates, (NH4)(2)MCl6 With M = Pd, Pt, Ir, Os, Re, Se, Sn, Te and Pb, comprise a set of compounds with systematically changing properties. The compounds may be ordered according to decreasing tunnelling frequency (TF) of ammonium ions, which is related to the increasing...... structure explain observed variation of the tunnelling frequencies for NH4+. The theory provides also M-Cl distances and barriers for C-2 and C-3 rotations of ammonium ions in respective compounds, which show good agreement with experimental values. (C) 2004 Elsevier B.V. All rights reserved....

  3. Stability of Large Parallel Tunnels Excavated in Weak Rocks: A Case Study

    Science.gov (United States)

    Ding, Xiuli; Weng, Yonghong; Zhang, Yuting; Xu, Tangjin; Wang, Tuanle; Rao, Zhiwen; Qi, Zufang

    2017-09-01

    Diversion tunnels are important structures for hydropower projects but are always placed in locations with less favorable geological conditions than those in which other structures are placed. Because diversion tunnels are usually large and closely spaced, the rock pillar between adjacent tunnels in weak rocks is affected on both sides, and conventional support measures may not be adequate to achieve the required stability. Thus, appropriate reinforcement support measures are needed, and the design philosophy regarding large parallel tunnels in weak rocks should be updated. This paper reports a recent case in which two large parallel diversion tunnels are excavated. The rock masses are thin- to ultra-thin-layered strata coated with phyllitic films, which significantly decrease the soundness and strength of the strata and weaken the rocks. The behaviors of the surrounding rock masses under original (and conventional) support measures are detailed in terms of rock mass deformation, anchor bolt stress, and the extent of the excavation disturbed zone (EDZ), as obtained from safety monitoring and field testing. In situ observed phenomena and their interpretation are also included. The sidewall deformations exhibit significant time-dependent characteristics, and large magnitudes are recorded. The stresses in the anchor bolts are small, but the extents of the EDZs are large. The stability condition under the original support measures is evaluated as poor. To enhance rock mass stability, attempts are made to reinforce support design and improve safety monitoring programs. The main feature of these attempts is the use of prestressed cables that run through the rock pillar between the parallel tunnels. The efficacy of reinforcement support measures is verified by further safety monitoring data and field test results. Numerical analysis is constantly performed during the construction process to provide a useful reference for decision making. The calculated deformations are in

  4. Fuel use and metabolic response to endurance exercise: a wind tunnel study of a long-distance migrant shorebird

    OpenAIRE

    Jenni-Eiermann, Susanne; Jenni, Lukas; Kvist, Anders; Lindström, Åke; Piersma, Theunis; Visser, G. Henk

    2002-01-01

    This study examines fuel use and metabolism in a group of long-distance migrating birds, red knots Calidris canutus (Scolopacidae), flying under controlled conditions in a wind tunnel for up to 10 h. Data are compared with values for resting birds fasting for the same time. Plasma levels of free fatty acids, glycerol and uric acid were elevated during flight, irrespective of flight duration (1–10 h). Triglyceride levels, the estimated concentration of very-low-density lipoproteins (VLDLs) and...

  5. Tunnelled haemodialysis catheter and haemodialysis outcomes: a retrospective cohort study in Zagreb, Croatia.

    Science.gov (United States)

    Pašara, Vedran; Maksimović, Bojana; Gunjača, Mihaela; Mihovilović, Karlo; Lončar, Andrea; Kudumija, Boris; Žabić, Igor; Knotek, Mladen

    2016-05-17

    Studies have reported that the tunnelled dialysis catheter (TDC) is associated with inferior haemodialysis (HD) patient survival, in comparison with arteriovenous fistula (AVF). Since many cofactors may also affect survival of HD patients, it is unclear whether the greater risk for survival arises from TDC per se, or from associated conditions. Therefore, the aim of this study was to determine, in a multivariate analysis, the long-term outcome of HD patients, with respect to vascular access (VA). Retrospective cohort study. This retrospective cohort study included all 156 patients with a TDC admitted at University Hospital Merkur, from 2010 to 2012. The control group consisted of 97 patients dialysed via AVF. The groups were matched according to dialysis unit and time of VA placement. The site of choice for the placement of the TDC was the right jugular vein. Kaplan-Meier analysis with log-rank test was used to assess patient survival. Multivariate Cox regression analysis was used to determine independent variables associated with patient survival. Patient survival with respect to VA. The cumulative 1-year survival of patients who were dialysed exclusively via TDC was 86.4% and of those who were dialysed exclusively via AVF, survival was 97.1% (p=0.002). In multivariate Cox regression analysis, male sex and older age were independently negatively associated with the survival of HD patients, while shorter HD vintage before the creation of the observed VA, hypertensive renal disease and glomerulonephritis were positively associated with survival. TDC was an independent risk factor for survival of HD patients (HR 23.0, 95% CI 6.2 to 85.3). TDC may be an independent negative risk factor for HD patient survival. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  6. Kinetics of the Thermal Decomposition of Tetramethylsilane behind the Reflected Shock Waves in a Single Pulse Shock Tube (SPST) and Modeling Study

    Science.gov (United States)

    Parandaman, A.; Sudhakar, G.; Rajakumar, B.

    Thermal reactions of Tetramethylsilane (TMS) diluted in argon were studied behind the reflected shock waves in a single-pulse shock tube (SPST) over the temperature range of 1085-1221 K and pressures varied between 10.6 and 22.8 atm. The stable products resulting from the decomposition of TMS were identified and quantified using gas chromatography and also verified with Fourier Transform Infrared (FTIR) spectrometer. The major reaction products are methane (CH4) and ethylene (C2H4). The minor reaction products are ethane (C2H6) and propylene (C3H6). The initiation of mechanism in the decomposition of TMS takes plays via the Si-C bond scission by ejecting the methyl radicals (CH3) and trimethylsilyl radicals ((CH3)3Si). The measured temperature dependent rate coefficient for the total decomposition of TMS was to be ktotal = 1.66 ×1015 exp (-64.46/RT) s-1 and for the formation of CH4 reaction channel was to be k = 2.20 × 1014 exp (-60.15/RT) s-1, where the activation energies are given in kcal mol-1. A kinetic scheme containing 17 species and 28 elementary reactions was used for the simulation using chemical kinetic simulator over the temperature range of 1085-1221 K. The agreement between the experimental and simulated results was satisfactory.

  7. Numerical studies of cavitation erosion on an elastic-plastic material caused by shock-induced bubble collapse

    Science.gov (United States)

    Turangan, C. K.; Ball, G. J.; Jamaluddin, A. R.; Leighton, T. G.

    2017-09-01

    We present a study of shock-induced collapse of single bubbles near/attached to an elastic-plastic solid using the free-Lagrange method, which forms the latest part of our shock-induced collapse studies. We simulated the collapse of 40 μm radius single bubbles near/attached to rigid and aluminium walls by a 60 MPa lithotripter shock for various scenarios based on bubble-wall separations, and the collapse of a 255 μm radius bubble attached to aluminium foil with a 65 MPa lithotripter shock. The coupling of the multi-phases, compressibility, axisymmetric geometry and elastic-plastic material model within a single solver has enabled us to examine the impingement of high-speed liquid jets from the shock-induced collapsing bubbles, which imposes an extreme compression in the aluminium that leads to pitting and plastic deformation. For certain scenarios, instead of the high-speed jet, a radially inwards flow along the aluminium surface contracts the bubble to produce a `mushroom shape'. This work provides methods for quantifying which parameters (e.g. bubble sizes and separations from the solid) might promote or inhibit erosion on solid surfaces.

  8. Wind Tunnel Measurement of Turbulent and Advective Scalar Fluxes: A Case Study on Intersection Ventilation

    Czech Academy of Sciences Publication Activity Database

    Kukačka, Libor; Nosek, Štěpán; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

    2012-01-01

    Roč. 2012, č. 381357 (2012), s. 1-13 ISSN 1537-744X Institutional research plan: CEZ:AV0Z20760514 Keywords : air pollution * atmospheric boundary layer * wind tunnel modelling * contaminant spreading * street canyon Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.730, year: 2012 http://www.tswj.com/2012/381357/

  9. A rotating bluff-body disc for reduced variability in wind tunnel aerosol studies.

    Science.gov (United States)

    Koehler, Kirsten A; Anthony, T Renee; van Dyke, Michael; Volckens, John

    2011-01-01

    A rotating bluff-body disc (RBD) was developed to reduce spatiotemporal variability associated with sampling supermicron aerosol in low-velocity wind tunnels. The RBD is designed to rotate eight personal aerosol samplers around a circular path in a forward-facing plane aligned with the wind tunnel cross section. Rotation of the RBD allows each sampler to traverse an identical path about the wind tunnel cross section, which reduces the effects of spatial heterogeneity associated with dispersing supermicron aerosol in low-velocity wind tunnels. Samplers are positioned on the face of the RBD via sampling ports, which connect to an air manifold on the back of the disc. Flow through each sampler was controlled with a critical orifice or needle valve, allowing air to be drawn through the manifold with a single pump. A metal tube, attached to this manifold, serves as both the axis of rotation and the flow conduction path (between the samplers and the vacuum source). Validation of the RBD was performed with isokinetic samplers and 37-mm cassettes. For facing-the-wind tests, the rotation of the RBD significantly decreased intra-sampler variability when challenged with particle diameters from 1 to 100 μm. The RBD was then employed to determine the aspiration efficiency of Institute of Occupational Medicine (IOM) personal samplers under a facing-the-wind condition. Operation of IOM samplers on the RBD reduced the between-sampler variability for all particle sizes tested.

  10. Scanning tunneling microscopy studies of thin foil x-ray mirrors

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Besenbacher, Flemming; Garnaes, Jorgen

    1990-01-01

    In this paper scanning tunneling microscopy (STM) measurements of x-ray mirrors are presented. The x-ray mirrors are 0.3 mm thick dip-lacquered aluminum foils coated with gold by evaporation, as well as state-of-the-art polished surfaces coated with gold, platinum, or iridium. The measurements...

  11. Dynamics of decanethiol self-assembled monolayers on Au(111) studied by Scanning tunnelling microscopy

    NARCIS (Netherlands)

    Wu, Hairong; Sotthewes, Kai; Kumar, Avijit; Vancso, Gyula J.; Schön, Peter Manfred; Zandvliet, Henricus J.W.

    2013-01-01

    We investigated the dynamics of decanethiol self-assembled monolayers on Au(111) surfaces using time-resolved scanning tunneling microscopy at room temperature. The expected ordered phases (β, δ, χ*, and ) and a disordered phase (ε) were observed. Current–time traces with the feedback loop disabled

  12. Oxidation process of AlOx-based magnetic tunnel junctions studied by photoconductance

    NARCIS (Netherlands)

    Koller, P.H.P.; Vanhelmont, F.W.M.; Boeve, H.; Lumens, P.G.E.; Jonge, de W.J.M.

    2003-01-01

    The oxidation process of Co/AlOx/Co magnetic tunnel junctions has been investigated by photoconductance, in addition to traditional transport measurements. The shape of the photoconductance curves is explained within the framework of a simple qualitative model, assuming an oxidation time dependent

  13. Surface x-ray scattering and scanning tunneling microscopy studies at the Au(111) electrode

    International Nuclear Information System (INIS)

    Ocko, B.M.; Magnussen, O.M.; Wang, J.X.; Adzic, R.R.

    1993-01-01

    This chapter reviews Surface X-ray Scattering and Scanning Tunneling Microscopy results carried out at the Au(111) surface under electrochemical conditions. Results are presented for the reconstructed surface, and for bromide and thallium monolayers. These examples are used to illustrate the complementary nature of the techniques

  14. Water-tunnel studies of heat balance in swimming mako sharks.

    Science.gov (United States)

    Bernal, D; Sepulveda, C; Graham, J B

    2001-12-01

    The mako shark (Isurus oxyrinchus) has specialized vascular networks (retia mirabilia) forming counter-current heat exchangers that allow metabolic heat retention in certain regions of the body, including the aerobic, locomotor red muscle and the viscera. Red muscle, white muscle and stomach temperatures were measured in juvenile (5-13.6 kg) makos swimming steadily in a water tunnel and exposed to stepwise square-wave changes in ambient temperature (T(a)) to estimate the rates of heat transfer and to determine their capacity for the activity-independent control of heat balance. The rates of heat gain of red muscle during warming were significantly higher than the rates of heat loss during cooling, and neither the magnitude of the change in T(a) nor the direction of change in T(a) had a significant effect on red muscle latency time. Our findings for mako red muscle are similar to those recorded for tunas and suggest modulation of retial heat-exchange efficiency as the underlying mechanism controlling heat balance. However, the red muscle temperatures measured in swimming makos (0.3-3 degrees C above T(a)) are cooler than those measured previously in larger decked makos. Also, the finding of non-stable stomach temperatures contrasts with the predicted independence from T(a) recorded in telemetry studies of mako and white sharks. Our studies on live makos provide new evidence that, in addition to the unique convergent morphological properties between makos and tunas, there is a strong functional similarity in the mechanisms used to regulate heat transfer.

  15. Feasibility study and technical proposal for seismic monitoring of tunnel boring machine in Olkiluoto

    Energy Technology Data Exchange (ETDEWEB)

    Saari, J.; Lakio, A. (AF-Consult Ltd, Vantaa (Finland))

    2009-01-15

    In Olkiluoto, Posiva Oy has operated a local seismic network since February 2002. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The studies include both tectonic and excavation-induced microearthquakes. An additional task of monitoring is related to safeguarding of the ONKALO. The possibility to excavate an illegal access to the ONKALO, have been concerned when the safeguards are discussed. Therefore all recorded explosions in the Olkiluoto area and in the ONKALO are located. If a concentration of explosions is observed, the origin of that is found out. Also a concept of hidden illegal explosions, detonated at the same time as the real excavation blasts, has been examined. According to the experience gained in Olkiluoto, it can be concluded that, as long the seismic network is in operation and the results are analysed by a skilled person, it is practically impossible to do illegal excavation by blasts. In this report a possibility of seismic monitoring of illegal excavation done by tunnel boring machine (TBM) has been investigated. Characteristics of the seismic signal generated by the raise boring machine are described. According to this study, it can be concluded that the generated seismic signal can be detected and the source of the signal can be located. However, this task calls for different kind of monitoring system than that, which is currently used for monitoring microearthquakes and explosions. The presented technical proposal for seismic monitoring of TBM in Olkiluoto is capable to detect and locate TBM coming outside the ONKALO area about two months before it would reach the ONKALO. (orig.)

  16. Feasibility study and technical proposal for seismic monitoring of tunnel boring machine in Olkiluoto

    International Nuclear Information System (INIS)

    Saari, J.; Lakio, A.

    2009-01-01

    In Olkiluoto, Posiva Oy has operated a local seismic network since February 2002. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The studies include both tectonic and excavation-induced microearthquakes. An additional task of monitoring is related to safeguarding of the ONKALO. The possibility to excavate an illegal access to the ONKALO, have been concerned when the safeguards are discussed. Therefore all recorded explosions in the Olkiluoto area and in the ONKALO are located. If a concentration of explosions is observed, the origin of that is found out. Also a concept of hidden illegal explosions, detonated at the same time as the real excavation blasts, has been examined. According to the experience gained in Olkiluoto, it can be concluded that, as long the seismic network is in operation and the results are analysed by a skilled person, it is practically impossible to do illegal excavation by blasts. In this report a possibility of seismic monitoring of illegal excavation done by tunnel boring machine (TBM) has been investigated. Characteristics of the seismic signal generated by the raise boring machine are described. According to this study, it can be concluded that the generated seismic signal can be detected and the source of the signal can be located. However, this task calls for different kind of monitoring system than that, which is currently used for monitoring microearthquakes and explosions. The presented technical proposal for seismic monitoring of TBM in Olkiluoto is capable to detect and locate TBM coming outside the ONKALO area about two months before it would reach the ONKALO. (orig.)

  17. Eye Movement Training and Suggested Gaze Strategies in Tunnel Vision - A Randomized and Controlled Pilot Study.

    Science.gov (United States)

    Ivanov, Iliya V; Mackeben, Manfred; Vollmer, Annika; Martus, Peter; Nguyen, Nhung X; Trauzettel-Klosinski, Susanne

    2016-01-01

    Degenerative retinal diseases, especially retinitis pigmentosa (RP), lead to severe peripheral visual field loss (tunnel vision), which impairs mobility. The lack of peripheral information leads to fewer horizontal eye movements and, thus, diminished scanning in RP patients in a natural environment walking task. This randomized controlled study aimed to improve mobility and the dynamic visual field by applying a compensatory Exploratory Saccadic Training (EST). Oculomotor responses during walking and avoiding obstacles in a controlled environment were studied before and after saccade or reading training in 25 RP patients. Eye movements were recorded using a mobile infrared eye tracker (Tobii glasses) that measured a range of spatial and temporal variables. Patients were randomly assigned to two training conditions: Saccade (experimental) and reading (control) training. All subjects who first performed reading training underwent experimental training later (waiting list control group). To assess the effect of training on subjects, we measured performance in the training task and the following outcome variables related to daily life: Response Time (RT) during exploratory saccade training, Percent Preferred Walking Speed (PPWS), the number of collisions with obstacles, eye position variability, fixation duration, and the total number of fixations including the ones in the subjects' blind area of the visual field. In the saccade training group, RTs on average decreased, while the PPWS significantly increased. The improvement persisted, as tested 6 weeks after the end of the training. On average, the eye movement range of RP patients before and after training was similar to that of healthy observers. In both, the experimental and reading training groups, we found many fixations outside the subjects' seeing visual field before and after training. The average fixation duration was significantly shorter after the training, but only in the experimental training condition

  18. X-ray absorption radiography for high pressure shock wave studies

    Science.gov (United States)

    Antonelli, L.; Atzeni, S.; Batani, D.; Baton, S. D.; Brambrink, E.; Forestier-Colleoni, P.; Koenig, M.; Le Bel, E.; Maheut, Y.; Nguyen-Bui, T.; Richetta, M.; Rousseaux, C.; Ribeyre, X.; Schiavi, A.; Trela, J.

    2018-01-01

    The study of laser compressed matter, both warm dense matter (WDM) and hot dense matter (HDM), is relevant to several research areas, including materials science, astrophysics, inertial confinement fusion. X-ray absorption radiography is a unique tool to diagnose compressed WDM and HDM. The application of radiography to shock-wave studies is presented and discussed. In addition to the standard Abel inversion to recover a density map from a transmission map, a procedure has been developed to generate synthetic radiographs using density maps produced by the hydrodynamics code DUED. This procedure takes into account both source-target geometry and source size (which plays a non negligible role in the interpretation of the data), and allows to reproduce transmission data with a good degree of accuracy.

  19. Three dimensional transient electromagnetic model study for fracture prediction from tunnel face; Sanjigen model keisan ni yoru TEM ho no tunnel zenpo tansa eno tekiyosei no kento

    Energy Technology Data Exchange (ETDEWEB)

    Wada, K; Tsutsui, T; Saito, A [Mitsui Mineral Development Engineering Co. Ltd., Tokyo (Japan); Hara, T [Toda Corp., Tokyo, (Japan); Zhdanov, M [University of Utah, UT (United States)

    1996-10-01

    In order to apply TEM model to fracture prediction at tunnel face, 3-D TEM model computation by FEM was conducted by installing a transmission loop on a tunnel face. MT field responses diffusing into the 3-D model were computed by time-domain difference calculus, and analytical precision was improved by introducing a staggered grid method. In the case where a low resistive zone exists before a tunnel face, time variance in diffused eddy current and induction current in the low resistive zone could be obtained. The difference in tunnel-axial transient curve (transient phenomenon curve in magnetic field) between uniform medium and low resistive zone models was based on the absorption process of diffused eddy current into the low resistive zone, and the expanding process of it toward the outside. Change in background condition could be predicted from the background and the ratio of transient curves every measurement. The detection limit of the low resistive zone was dependent on resistivity contrast, distance and geometry. Fluctuation in measurement due to noises and S/N ratio were also essential. 3 refs., 10 figs.

  20. Shock loading and reactive flow modeling studies of void induced AP/AL/HTPB propellant

    Science.gov (United States)

    Miller, P. J.; Lindfors, A. J.

    1998-07-01

    The unreactive Hugoniot of a class 1.3 propellant has been investigated by shock compression experiments. The results are analyzed in terms of an ignition and growth reactive flow model using the DYNA2D hydrocode. The calculated shock ignition parameters of the model show a linear dependence on measured void volume which appears to reproduce the observed gauge records well. Shock waves were generated by impact in a 75 mm single stage powder gun. Manganin and PVDF pressure gauges provided pressure-time histories to 140 kbar. The propellants were of similar formulation differing only in AP particle size and the addition of a burn rate modifer (Fe2O3) from that of previous investigations. Results show neglible effect of AP particle size on shock response in contrast to the addition of Fe2O3 which appears to `stiffen' the unreactive Hugoniot and enhances significantly the reactive rates under shock. The unreactive Hugoniot, within experimental error, compares favorably to the solid AP Hugoniot. Shock experiments were performed on propellant samples strained to induce insitu voids. The material state was quantified by uniaxial tension dialatometry. The experimental records show a direct correlation between void volume (0 to 1.7%) and chemical reactivity behind the shock front. These results are discussed in terms of `hot spot' ignition resulting from the shock collapse of the voids.

  1. Co on Pt(111) studied by spin-polarized scanning tunneling microscopy and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Meier, F.K.

    2006-07-01

    In this thesis the electronic properties of the bare Pt(111) surface, the structural, electronic, and magnetic properties of monolayer and double-layer high Co nanostructures as well as the spin-averaged electronic structure of single Co atoms on Pt(111) were studied by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). The experiments on the bare Pt(111) surface and on single Co atoms have been performed in an STM facility operating at temperatures of down to 0.3 K and at magnetic fields of up to 14 T under ultra-high vacuum conditions. The facility has been taken into operation within the time period of this thesis and its specifications were tested by STS measurements. These characterization measurements show a very high stability of the tunneling junction and an energy resolution of about 100 {mu}eV, which is close to the thermal limit. The investigation of the electronic structure of the bare Pt(111) surface reveals the existence of an unoccupied surface state. By a comparison of the measured dispersion to first-principles electronic structure calculations the state is assigned to an sp-derived surface band at the lower boundary of the projected bulk band gap. The surface state exhibits a strong spin-orbit coupling induced spin splitting. The close vicinity to the bulk bands leads to a strong linear contribution to the dispersion and thus to a deviant appearance in the density of states in comparison to the surface states of the (111) surfaces of noble metals. A detailed study of Co monolayer and double-layer nanostructures on the Pt(111) surface shows that both kinds of nanostructures exhibit a highly inhomogeneous electronic structure which changes at the scale of only a few Aa due to a strong stacking dependence with respect to the Pt(111) substrate. With the help of first principles calculations the different spectroscopic appearance for Co atoms within the Co monolayer is assigned to a stacking dependent hybridization of Co states

  2. Recognition tunneling

    Czech Academy of Sciences Publication Activity Database

    Lindsay, S.; He, J.; Sankey, O.; Hapala, Prokop; Jelínek, Pavel; Zhang, P.; Chang, S.; Huang, S.

    2010-01-01

    Roč. 21, č. 26 (2010), 262001/1-262001/12 ISSN 0957-4484 R&D Projects: GA ČR GA202/09/0545 Institutional research plan: CEZ:AV0Z10100521 Keywords : STM * tunneling current * molecular electronics * DFT calculations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.644, year: 2010

  3. Studies on the propagation of relativistic plasma waves in high density plasmas produced by hypersonic ionizing shock waves

    International Nuclear Information System (INIS)

    Williams, R.L.; Johnson, J.A. III

    1993-01-01

    The feasibility of using an ionizing shock wave to produce high density plasmas suitable for the propagation large amplitude relativistic plasma waves is being investigated. A 20 kv arc driven shock tube of coaxial geometry produces a hypersonic shock wave (10 p > 10 17 cm -3 ). The shock can be made to reflect off the end of the tube, collide with its wake, and thus increase the plasma density further. After reflecting, the plasma is at rest. The shock speed is measured using piezoelectric pressure probes and the ion density is measured using laser induced fluorescence (LIF) techniques on argon 488.0 nm and 422.8 nm lines. The future plans are to excite large amplitude relativistic plasma waves in this plasma by either injecting a short pulse laser (Laser Wake Field Scheme), two beating lasers (Plasma Beat Wave Scheme), or a short bunch of relativistic electrons (Plasma Wake Field Scheme). Results of recent computational and theoretical studies, as well as initial experimental measurements on the plasma using LIF, are reported. Implications for the application of high density plasmas produced in this way to such novel schemes as the plasma wave accelerator, photon accelerator, plasma wave undulator, and also plasma lens, are discussed. The effect of plasma turbulence is also discussed

  4. Comprehensive study on the pressure dependence of shock wave plasma generation under TEA CO2 laser bombardment on metal sample

    International Nuclear Information System (INIS)

    Marpaung, A.M.; Kurniawan, H.; Tjia, M.O.; Kagawa, K.

    2001-01-01

    An experimental study has been carried out on the dynamical process taking place in the plasma generated by a TEA CO 2 laser (400 mJ, 100 ns) on a zinc target when surrounded by helium gas of pressure ranging from 2 Torr to 1 atm. Plasma characteristics were examined in detail on the emission lines of Zn I 481.0 nm and He I 587.6 nm by means of an unique time-resolved spatial distribution technique in addition to an ordinary time-resolved emission measurement technique. The results reveal, for the first time, persistent shock wave characteristics in all cases throughout the entire pressure range considered. Further analysis of the data has clarified the distinct characteristics of laser plasmas generated in different ranges of gas pressure. It is concluded that three types of shock wave plasma can be identified; namely, a target shock wave plasma in the pressure range from 2 Torr to around 50 Torr; a coupling shock wave plasma in the pressure range from around 50 Torr to 200 Torr and a gas breakdown shock wave plasma in the pressure range from around 200 Torr to 1 atm. These distinct characteristics are found to be ascribable to the different extents of the gas breakdown process taking place at the different gas pressures. These results, obtained for a TEA CO 2 laser, will provide a useful basis for the analyses of plasmas induced by other lasers. (author)

  5. Experimental study on tunnel lining joints temporarily strengthened by SMA bolts

    International Nuclear Information System (INIS)

    Wu, Bo; Ou, Yunlong

    2014-01-01

    Shield tunnels have been widely used in city metros all over the world. During the long-term period of the metro operation, the joints of shield tunnel’s neighboring segments may degrade due to some environmental factors, leading to the increasing of the joint opening and some resulting adverse consequences. In this paper, a temporary strengthening method by using shape memory alloy (SMA) bolts is proposed and experimentally studied for the joints of neighboring segments, and a revised electric heating method which suits with the strengthening method is presented and experimentally validated for the SMA bolts. The purpose of the proposed temporary strengthening method is to create favorable conditions for the following permanent strengthening. Test results show that: (a) for the joints of shield tunnel’s neighboring segments, the strengthening method can effectively reduce the joint opening, joint deflection, concrete strain in joint’s compression zone, and strain of joint’s steel bolts; (b) the revised electric heating method can be used to heat the SMA rod to a temperature higher than the SMA’s austenite finish temperature quickly, and the average heating rate related to Type 2 inner resistance element is larger than that related to Type 1 inner resistance element; and (c) the reduction percentages of the joint opening increment, joint deflection, concrete strain in joint’s compression zone, and strain of joint’s steel bolts for Specimen I are all larger than those for Specimen II, implying that the less the joint opening is, the more significant the strengthening effect is. (paper)

  6. Wind tunnel experimental study on the effect of PAM on soil wind erosion control.

    Science.gov (United States)

    He, Ji-Jun; Cai, Qiang-Guo; Tang, Ze-Jun

    2008-10-01

    In recent years, high-molecular-weight anionic polyacrylamide (PAM) have been widely tested on a variety of soils, primarily in water erosion control. However, little information is available regarding the effectiveness of PAM on preventing soil loss from wind erosion. The research adopted room wind tunnel experiment, two kinds of soils were used which were from the agro-pastoral area of Inner Mongolia, the northwest of China, the clay content of soils were 22.0 and 13.7%, respectively. For these tests, all the treatments were performed under the condition of wind velocity of 14 m s(-1) and a blown angle of 8.75%, according to the actual situation of experimented area. The study results indicated that using PAM on the soil surface could enhance the capability of avoiding the wind erosion, at the same time, the effect of controlling wind soil erosion with 4 g m(-2) PAM was better than 2 g m(-2) PAM's. Economically, the 2 g m(-2) PAM used in soil surface can control wind erosion effectively in this region. The prophase PAM accumulated in soil could not improve the capability of avoiding the wind erosion, owing to the degradation of PAM in the soil and the continual tillage year after year. The texture of soil is a main factor influencing the capability of soil avoiding wind erosion. Soil with higher clay content has the higher capability of preventing soil from wind erosion than one with the opposite one under the together action of PAM and water.

  7. Screening for Acromegaly in Patients with Carpal Tunnel Syndrome: A Prospective Study (ACROCARP).

    Science.gov (United States)

    Zoicas, F; Kleindienst, A; Mayr, B; Buchfelder, M; Megele, R; Schöfl, C

    2016-07-01

    Early diagnosis of acromegaly prevents irreversible comorbidities and facilitates surgical cure. Carpal tunnel syndrome (CTS) is common in acromegaly and patients have often undergone surgery for CTS prior to the diagnosis of acromegaly. We hypothesized that screening CTS-patients for acromegaly could facilitate active case-finding. We prospectively enrolled 196 patients [135 women, 56.9 (range 23-103) years] who presented with CTS for surgery. Patients were asked about 6 symptoms suggestive of acromegaly using a questionnaire calculating a symptom score (0-6 points), and insulin-like-growth factor 1 (IGF-1) was measured. If IGF-1 was increased, IGF-1 measurement was repeated, and random growth hormone (GH) and/or an oral glucose tolerance test (OGTT) with assessment of GH-suppression were performed. The mean symptom score was 1.7±1.3 points. Three patients reported the maximal symptom score of 6 points, but none of them had an increased IGF-1. There was no correlation between the symptom score and IGF-1-SDS (standard deviation score) (r=0.026; p=0.71). Four patients had an IGF-1>2 SDS. In 2 patients acromegaly was ruled out using random GH and OGTT. One patient had normal IGF-1 and random GH at follow-up. One patient refused further diagnostics. In this prospective cohort of patients with CTS, the observed frequency of acromegaly was at most 0.51% (95% CI 0.03 to 2.83%). In this prospective study, none of the 196 patients with CTS had proven acromegaly. Thus, we see no evidence to justify general screening of patients with CTS for acromegaly. © Georg Thieme Verlag KG Stuttgart · New York.

  8. A wind tunnel study on the effect of trees on PM2.5 distribution around buildings.

    Science.gov (United States)

    Ji, Wenjing; Zhao, Bin

    2018-03-15

    Vegetation, especially trees, is effective in reducing the concentration of particulate matter. Trees can efficiently capture particles, improve urban air quality, and may further decrease the introduction of outdoor particles to indoor air. The objective of this study is to investigate the effects of trees on particle distribution and removal around buildings using wind tunnel experiments. The wind tunnel is 18m long, 12m wide, and 3.5m high. Trees were modeled using real cypress branches to mimic trees planted around buildings. At the inlet of the wind tunnel, a "line source" of particles was released, simulating air laden with particulate matter. Experiments with the cypress tree and tree-free models were conducted to compare particle concentrations around the buildings. The results indicate that cypress trees clearly reduce PM 2.5 concentrations compared with the tree-free model. The cypress trees enhanced the PM 2.5 removal rate by about 20%. The effects of trees on PM 2.5 removal and distribution vary at different heights. At the base of the trees, their effect on reducing PM 2.5 concentrations is the most significant. At a great height above the treetops, the effect is almost negligible. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. High-energy air shock study in steel and grout pipes

    International Nuclear Information System (INIS)

    Glenn, H.D.; Kratz, H.R.; Keough, D.D.; Duganne, D.A.; Ruffner, D.J.; Swift, R.P.; Baum, D.

    1979-01-01

    Voitenko compressors are used to generate 43 mm/μs air shocks in both a steel and a grout outlet pipe containing ambient atmospheric air. Fiber-optic ports provide diaphragm burst times, time-of-arrival (TOA) data, and velocities for the shock front along the 20-mm-ID exit pipes. Pressure profiles are obtained at higher enthalpy shock propagation than ever before and at many locations along the exit pipes. Numerous other electronic sensors and postshot observations are described, as well as experimental results. The primary objectives of the experiments are as follows: (1) provide a data base for normalization/improvement of existing finite-difference codes that describe high-energy air shocks and gas propagation; (2) obtain quantitative results on the relative attenuation effects of two very different wall materials for high-energy air shocks and gas flows. The extensive experimental results satisfy both objectives

  10. Interaction Driven Interband Tunneling of Bosons in the Triple Well

    OpenAIRE

    Cao, Lushuai; Brouzos, Ioannis; Zöllner, Sascha; Schmelcher, Peter

    2010-01-01

    We study the tunneling of a small ensemble of strongly repulsive bosons in a one-dimensional triple-well potential. The usual treatment within the single-band approximation suggests suppression of tunneling in the strong interaction regime. However, we show that several windows of enhanced tunneling are opened in this regime. This enhanced tunneling results from higher band contributions, and has the character of interband tunneling. It can give rise to various tunneling processes, such as si...

  11. Study of dust re-suspension at low pressure in a dedicated wind-tunnel

    Science.gov (United States)

    Rondeau, Anthony; Sabroux, Jean-Christophe; Chassefière, Eric

    2015-04-01

    The atmosphere of several telluric planets or satellites are dusty. Such is the case of Earth, Venus, Mars and Titan, each bearing different aeolian processes linked principally to the kinematic viscosity of the near-surface atmosphere. Studies of the Martian atmosphere are particularly relevant for the understanding of the dust re-suspension phenomena at low pressure (7 mbar). It turns out that operation of fusion reactors of the tokamak design produces significant amount of dust through the erosion of plasma-facing components. Such dust is a key issue, both regarding the performance and the safety of a fusion reactor such as ITER, under construction in Cadarache, France. Indeed, to evaluate the explosion risk in the ITER fusion reactor, it is essential to quantify the re-suspended dust fraction as a function of the dust inventory that can be potentially mobilized during a loss of vacuum accident (LOVA), with air or water vapour ingress. A complete accident sequence will encompass dust re-suspension from near-vacuum up to atmospheric pressure. Here, we present experimental results of particles re-suspension fractions measured at 1000, 600 and 300 mbar in the IRSN BISE (BlowIng facility for airborne releaSE) wind tunnel. Both dust monolayer deposits and multilayer deposits were investigated. In order to obtain experimental re-suspension data of dust monolayer deposits, we used an optical microscope allowing to measure the re-suspended particles fraction by size intervals of 1 µm. The deposits were made up of tungsten particles on a tungsten surface (an ubiquitous plasma facing component) and alumina particles on a glass plate, as a surrogate. A comparison of the results with the so-called Rock'nRoll dust re-suspension model (Reeks and Hall, 2001) is presented and discussed. The multilayer deposits were made in a vacuum sedimentation chamber allowing to obtain uniform deposits in terms of thickness. The re-suspension experimental data of such deposits were obtained

  12. Pooling job physical exposure data from multiple independent studies in a consortium study of carpal tunnel syndrome

    Science.gov (United States)

    Kapellusch, Jay M.; Garg, Arun; Bao, Stephen S.; Silverstein, Barbara A.; Burt, Susan E.; Dale, Ann Marie; Evanoff, Bradley A.; Gerr, Frederic E.; Harris-Adamson, Carisa; Hegmann, Kurt T.; Merlino, Linda A.; Rempel, David M.

    2015-01-01

    Pooling data from different epidemiological studies of musculoskeletal disorders (MSDs) is necessary to improve statistical power and to more precisely quantify exposure–response relationships for MSDs. The pooling process is difficult and time-consuming, and small methodological differences could lead to different exposure–response relationships. A subcommittee of a six-study research consortium studying carpal tunnel syndrome: (i) visited each study site, (ii) documented methods used to collect physical exposure data and (iii) determined compatibility of exposure variables across studies. Certain measures of force, frequency of exertion and duty cycle were collected by all studies and were largely compatible. A portion of studies had detailed data to investigate simultaneous combinations of force, frequency and duration of exertions. Limited compatibility was found for hand/wrist posture. Only two studies could calculate compatible Strain Index scores, but Threshold Limit Value for Hand Activity Level could be determined for all studies. Challenges of pooling data, resources required and recommendations for future researchers are discussed. PMID:23697792

  13. Studies on fatigue life enhancement of pre-fatigued spring steel specimens using laser shock peening

    International Nuclear Information System (INIS)

    Ganesh, P.; Sundar, R.; Kumar, H.; Kaul, R.; Ranganathan, K.; Hedaoo, P.; Raghavendra, G.; Anand Kumar, S.; Tiwari, P.; Nagpure, D.C.; Bindra, K.S.; Kukreja, L.M.; Oak, S.M.

    2014-01-01

    Highlights: • Laser peening significantly extended fatigue life of pre-fatigued spring steel. • Increase in fatigue life of laser peened specimens was more than 15 times. • Black PVC tape is an effective coating for laser peening of ground surfaces. • Repeat peening repaired local surface melted regions on laser peened surface. • Technique is effective for life extension of in-service automobile parts. - Abstract: SAE 9260 spring steel specimens after enduring 50% of their mean fatigue life were subjected to laser shock peening using an in-house developed 2.5 J/7 ns pulsed Neodymium-doped Yttrium Aluminum Garnet (Nd:YAG) laser for studying their fatigue life enhancement. In the investigated range of process parameters, laser shock peening resulted in the extension of fatigue life of these partly fatigue damaged specimens by more than 15 times. Contributing factors for the enhanced fatigue life of laser peened specimens are: about 400 μm thick compressed surface layer with magnitude of surface stress in the range of −600 to −700 MPa, about 20% increase in surface hardness and unaltered surface finish. For laser peening of ground steel surface, an adhesive-backed black polyvinyl chloride (PVC) tape has been found to be a superior sacrificial coating than conventionally used black paint. The effect of repeated laser peening treatment was studied to repair locally surface melted regions and the treatment has been found to be effective in re-establishing desired compressive stress pattern on the erstwhile tensile-stressed surface

  14. Pressure vessel fracture studies pertaining to a PWR LOCA-ECC thermal shock: experiments TSE-1 and TSE-2

    International Nuclear Information System (INIS)

    Cheverton, R.D.

    1976-09-01

    The LOCA-ECC Thermal Shock Program was established to investigate the potential for flaw propagation in pressurized-water reactor (PWR) vessels during injection of emergency core coolant following a loss-of-coolant accident. Studies thus far have included fracture mechanics analyses of typical PWRs, the design and construction of a thermal shock test facility, determination of material properties for test specimens, and two thermal shock experiments with 0.53-m-OD (21-in.) by 0.15-m-wall (6-in.) cylindrical test specimens. The PWR calculations indicated that under some circumstances crack propagation could be expected and that experiments should be conducted for cracks that would have the potential for propagation at least halfway through the wall

  15. X-ray line broadening studies on aluminum nitride, titanium carbide and titanium diboride modified by high pressure shock loading

    International Nuclear Information System (INIS)

    Morosin, B.; Graham, R.A.

    1983-01-01

    Powders of AlN, TiC and TiB 2 have been subjected to controlled shock loading with peak pressures in the samples between 14 to 27 GPa and preserved for post-shock study. Broadened x-ray diffraction peak profiles are analyzed by a simplified method and show increases in residual lattice strain and small decreases in crystallite size. Strain values range from 10 -5 to 10 -4 for TiB 2 and to values larger than 10 -3 for TiC and AlN

  16. Prognostic impact of isolated right ventricular dysfunction in sepsis and septic shock: an 8-year historical cohort study.

    Science.gov (United States)

    Vallabhajosyula, Saraschandra; Kumar, Mukesh; Pandompatam, Govind; Sakhuja, Ankit; Kashyap, Rahul; Kashani, Kianoush; Gajic, Ognjen; Geske, Jeffrey B; Jentzer, Jacob C

    2017-09-07

    Echocardiographic myocardial dysfunction is reported commonly in sepsis and septic shock, but there are limited data on sepsis-related right ventricular dysfunction. This study sought to evaluate the association of right ventricular dysfunction with clinical outcomes in patients with severe sepsis and septic shock. Historical cohort study of adult patients admitted to all intensive care units at the Mayo Clinic from January 1, 2007 through December 31, 2014 for severe sepsis and septic shock, who had an echocardiogram performed within 72 h of admission. Patients with prior heart failure, cor-pulmonale, pulmonary hypertension and valvular disease were excluded. Right ventricular dysfunction was defined by the American Society of Echocardiography criteria. Outcomes included 1-year survival, in-hospital mortality and length of stay. Right ventricular dysfunction was present in 214 (55%) of 388 patients who met the inclusion criteria-isolated right ventricular dysfunction was seen in 100 (47%) and combined right and left ventricular dysfunction in 114 (53%). The baseline characteristics were similar between cohorts except for the higher mechanical ventilation use in patients with isolated right ventricular dysfunction. Echocardiographic findings demonstrated lower right ventricular and tricuspid valve velocities in patients with right ventricular dysfunction and lower left ventricular ejection fraction and increased mitral E/e' ratios in patients with combined right and left ventricular dysfunction. After adjustment for age, comorbidity, illness severity, septic shock and use of mechanical ventilation, isolated right ventricular dysfunction was independently associated with worse 1-year survival-hazard ratio 1.6 [95% confidence interval 1.2-2.1; p = 0.002) in patients with sepsis and septic shock. Isolated right ventricular dysfunction is seen commonly in sepsis and septic shock and is associated with worse long-term survival.

  17. INTERFERENCE OF UNIDIRECTIONAL SHOCK WAVES

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2015-05-01

    Full Text Available Subject of study.We consider interference of unidirectional shock waves or, as they are called, catching up shock waves. The scope of work is to give a classification of the shock-wave structures that arise in this type of interaction of shock waves, and the area of their existence. Intersection of unidirectional shock waves results in arising of a shock-wave structure at the intersection point, which contains the main shock wave, tangential discontinuity and one more reflected gas-dynamic discontinuity of unknown beforehand type. The problem of determining the type of reflected discontinuity is the main problem that one has to solve in the study of catching shock waves interference. Main results.The paper presents the pictures of shock-wave structures arising at the interaction of catching up shock waves. The areas with a regular and irregular unidirectional interaction of shocks are described. Characteristic shock-wave structures are of greatest interest, where reflected gas-dynamic discontinuity degenerates into discontinuous characteristics. Such structures have a number of extreme properties. We have found the areas of existence for such shock-wave structures. There are also areas in which the steady-state solution is not available. The latter has determined revival of interest for the theoretical study of the problem, because the facts of sudden shock-wave structure destruction inside the air intake of supersonic aircrafts at high Mach numbers have been discovered. Practical significance.The theory of interference for unidirectional shock waves and design procedure are usable in the design of supersonic air intakes. It is also relevant for application possibility investigation of catching up oblique shock waves to create overcompressed detonation in perspective detonation air-jet and rocket engines.

  18. Spin tunnelling in mesoscopic systems

    Indian Academy of Sciences (India)

    We study spin tunnelling in molecular magnets as an instance of a mesoscopic phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel splitting between various pairs of Zeeman levels in this molecule oscillates as a function of applied magnetic field, vanishing completely at special points in the ...

  19. Shock tube and modeling study of 2,7-dimethyloctane pyrolysis and oxidation

    KAUST Repository

    Li, Sijie; Sarathy, Mani; Davidson, David Frank; Hanson, Ronald Kenneth; Westbrook, Charles K.

    2015-01-01

    High molecular weight iso-paraffinic molecules are found in conventional petroleum, Fischer-Tropsch (FT), and other alternative hydrocarbon fuels, yet fundamental combustion studies on this class of compounds are lacking. In the present work, ignition delay time measurements in 2,7-dimethyloctane/air were carried out behind reflected shock waves using conventional and constrained reaction volume (CRV) methods. The ignition delay time measurements covered the temperature range 666-1216K, pressure range 12-27atm, and equivalence ratio of 0.5 and 1. The ignition delay time temperatures span the low-, intermediate- and high-temperature regimes for 2,7-dimethyloctane (2,7-DMO) oxidation. Clear evidence of negative temperature coefficient behavior was observed near 800K. Fuel time-history measurements were also carried out in pyrolysis experiments in mixtures of 2000ppm 2,7-DMO/argon at pressures near 16 and 35atm, and in the temperature range of 1126-1455K. Based on the fuel removal rates, the overall 2,7-DMO decomposition rate constant can be represented with k =4.47×105 exp(-23.4[kcal/mol]/RT) [1/s]. Ethylene time-history measurements in pyrolysis experiments at 16atm are also provided. The current shock tube dataset was simulated using a novel chemical kinetic model for 2,7-DMO. The reaction mechanism includes comprehensive low- and high-temperature reaction classes with rate constants assigned using established rules. Comparisons between the simulated and experimental data show simulations reproduce the qualitative trends across the entire range of conditions tested. However, the present kinetic modeling simulations cannot quantitatively reproduce a number of experimental data points, and these are analyzed herein.

  20. Shock tube studies of methyl butanoate pyrolysis with relevance to biodiesel

    KAUST Repository

    Farooq, Aamir

    2012-11-01

    Methyl butanoate pyrolysis and decomposition pathways were studied in detail by measuring concentration time-histories of CO, CO 2, CH 3, and C 2H 4 using shock tube/laser absorption methods. Experiments were conducted behind reflected shock waves at temperatures of 1200-1800K and pressures near 1.5atm using mixtures of 0.1%, 0.5%, and 1% methyl butanoate in Argon. A novel laser diagnostic was developed to measure CO in the ν 1 fundamental vibrational band near 4.56μm using a new generation of quantum-cascade lasers. Wavelength modulation spectroscopy with second-harmonic detection (WMS-2f) was used to measure CO 2 near 2752nm. Methyl radical was measured using UV laser absorption near 216nm, and ethylene was monitored using IR gas laser absorption near 10.53μm. An accurate methyl butanoate model is critical in the development of mechanisms for larger methyl esters, and the measured time-histories provide kinetic targets and strong constraints for the refinement of the methyl butanoate reaction mechanism. Measured CO mole fractions reach plateau values that are the same as the initial fuel mole fraction at temperatures higher than 1500K over the maximum measurement time of 2ms or less. Two recent kinetic mechanisms are compared with the measured data and the possible reasons for this 1:1 ratio between MB and CO are discussed. Based on these discussions, it is expected that similar CO/fuel and CO 2/fuel ratios for biodiesel molecules, particularly saturated components of biodiesel, should occur. © 2012 The Combustion Institute.

  1. Shock tube and modeling study of 2,7-dimethyloctane pyrolysis and oxidation

    KAUST Repository

    Li, Sijie

    2015-05-01

    High molecular weight iso-paraffinic molecules are found in conventional petroleum, Fischer-Tropsch (FT), and other alternative hydrocarbon fuels, yet fundamental combustion studies on this class of compounds are lacking. In the present work, ignition delay time measurements in 2,7-dimethyloctane/air were carried out behind reflected shock waves using conventional and constrained reaction volume (CRV) methods. The ignition delay time measurements covered the temperature range 666-1216K, pressure range 12-27atm, and equivalence ratio of 0.5 and 1. The ignition delay time temperatures span the low-, intermediate- and high-temperature regimes for 2,7-dimethyloctane (2,7-DMO) oxidation. Clear evidence of negative temperature coefficient behavior was observed near 800K. Fuel time-history measurements were also carried out in pyrolysis experiments in mixtures of 2000ppm 2,7-DMO/argon at pressures near 16 and 35atm, and in the temperature range of 1126-1455K. Based on the fuel removal rates, the overall 2,7-DMO decomposition rate constant can be represented with k =4.47×105 exp(-23.4[kcal/mol]/RT) [1/s]. Ethylene time-history measurements in pyrolysis experiments at 16atm are also provided. The current shock tube dataset was simulated using a novel chemical kinetic model for 2,7-DMO. The reaction mechanism includes comprehensive low- and high-temperature reaction classes with rate constants assigned using established rules. Comparisons between the simulated and experimental data show simulations reproduce the qualitative trends across the entire range of conditions tested. However, the present kinetic modeling simulations cannot quantitatively reproduce a number of experimental data points, and these are analyzed herein.

  2. Tunnel - history of

    International Nuclear Information System (INIS)

    1998-11-01

    This book introduces history of tunnel in ancient times, the middle ages and modern times, survey of tunnel and classification of bedrock like environment survey of position, survey of the ground, design of tunnel on basic thing of the design, and design of tunnel of bedrock, analysis of stability of tunnel and application of the data, construction of tunnel like lattice girder and steel fiber reinforced shot crete, and maintenance control and repair of tunnel.

  3. Molecular electronics of a single photosystem I reaction center: Studies with scanning tunneling microscopy and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, I.; Lee, J.W.; Warmack, R.J.; Allison, D.P.; Greenbaum, E. [Oak Ridge National Lab., TN (United States)

    1995-03-14

    Thylakoids and photosystem I (PSI) reaction centers were imaged by scanning tunneling microscopy. The thylakoids were isolated from spinach chloroplasts, and PSI reaction centers were extracted from thylakoid membranes. Because thylakoids are relatively thick nonconductors, they were sputter-coated with Pd/Au before imaging. PSI photosynthetic centers and chemically platinized PSI were investigated without sputter-coating. They were mounted on flat gold substrates that had been treated with mercaptoacetic acid to help bind the proteins. With tunneling spectroscopy, the PSI centers displayed a semiconductor-like response with a band gap of 1.8 eV. Lightly platinized (platinized for 1 hr) centers displayed diode-like conduction that resulted in dramatic contrast changes between images taken with opposite bias voltages. The electronic properties of this system were stable under long-term storage. 42 refs., 7 figs.

  4. Performance studies of solar tunnel dryer for drying aonla (Embilica Officinalis) pulp

    International Nuclear Information System (INIS)

    Seveda, M. S.

    2012-01-01

    A solar tunnel dryer was constructed and evaluated the performance for drying aonla pulp. The dryer consists of a transparent UV stabilized plastic covered solar collector cum drying unit. Evaluation parameters are air temperature, solar insolation, moisture content, relative humidity and airflow rate. A minimum of 111.18 m 2 solar collector area is required to dry a batch 1000 kg aonla pulp in 16 hours (two days drying period). The initial and final moisture content considered were 424.93 and 10.08% dry basis, respectively. It was observed that on an average 43 per cent of higher temperature was obtained in solar tunnel dryer over the ambient temperature. The results obtained during the test period denoted that the maximum gained energy occurred at 13 o'clock hour and then gradually declined since the maximum solar radiation occurred at this time. (author)

  5. Wind tunnel study of helical and straight-bladed vertical-axis wind turbine wakes

    Science.gov (United States)

    Bagheri, Maryam; Araya, Daniel

    2017-11-01

    It is hypothesized that blade curvature can serve as a passive means to control fluid entrainment and wake recovery in vertical-axis wind turbine (VAWT) arrays. We test this experimentally in a wind tunnel using two different VAWT configurations, one with straight blades and another with helical blades, keeping all other experimental parameters fixed. A small-scale, commercially available VAWT (15W max power) is used as the baseline wind tunnel model in each case. The commercial VAWT blades are replaced with either straight or helical blades that are 3D-printed extrusions of the same airfoil cross-section. Results from smoke flow visualization, three-component wake velocity measurements, and turbine power data are presented. These results give insight into the potential use of VAWTs with curved blades in utility-scale wind farms.

  6. Study on construction technology of metro tunnel under a glass curtain wall

    Science.gov (United States)

    Zhang, Jian; Yu, Deqiang

    2018-03-01

    To ensure the safety of the glass curtain wall building above loess tunnel and get an optimal scheme, an elastic-plastic FEM model is established to simulate three reinforcement schemes based on a tunnel section in Xi’an Metro Line 3. The results show that the settlement value of the optimal scheme is reduced by 69.89% compared with the drainage measures, and the uneven settlement value is reduced by 57.5%. The construction points, technical processes and technical indexes of the optimal scheme are introduced. According to the actual project, the cumulative settlement of the building under construction is 16mm, which meets the control standards. According to the actual project, the cumulative settlement of the glass curtain wall building is 16mm, which meets the control standards. The reinforcement scheme can provide some reference for the design and construction of the metro in loess area.

  7. Studying the universality of field induced tunnel ionization times via high-order harmonic spectroscopy

    International Nuclear Information System (INIS)

    Soifer, H; Bruner, B D; Dudovich, N; Negro, M; Devetta, M; Vozzi, C; Faccialà, D; Silvestri, S de; Stagira, S

    2014-01-01

    High-harmonic generation spectroscopy is a promising tool for resolving electron dynamics and structure in atomic and molecular systems. This scheme, commonly described by the strong field approximation, requires a deep insight into the basic mechanism that leads to the harmonic generation. Recently, we have demonstrated the ability to resolve the first stage of the process—field induced tunnel ionization—by adding a weak perturbation to the strong fundamental field. Here we generalize this approach and show that the assumptions behind the strong field approximation are valid over a wide range of tunnel ionization conditions. Performing a systematic study—modifying the fundamental wavelength, intensity and atomic system—we observed a good agreement with quantum path analysis over a range of Keldysh parameters. The generality of this scheme opens new perspectives in high harmonics spectroscopy, holding the potential of probing large, complex molecular systems. (paper)

  8. A novel Tunneling Graphene Nano Ribbon Field Effect Transistor with dual material gate: Numerical studies

    Science.gov (United States)

    Ghoreishi, Seyed Saleh; Saghafi, Kamyar; Yousefi, Reza; Moravvej-farshi, Mohammad Kazem

    2016-09-01

    In this work, we present Dual Material Gate Tunneling Graphene Nano-Ribbon Field Effect Transistors (DMG-T-GNRFET) mainly to suppress the am-bipolar current with assumption that sub-threshold swing which is one of the important characteristics of tunneling transistors must not be degraded. In the proposed structure, dual material gates with different work functions are used. Our investigations are based on numerical simulations which self-consistently solves the 2D Poisson based on an atomistic mode-space approach and Schrodinger equations, within the Non-Equilibrium Green's (NEGF). The proposed device shows lower off-current and on-off ratio becomes 5order of magnitude greater than the conventional device. Also two different short channel effects: Drain Induced Barrier Shortening (DIBS) and hot-electron effect are improved in the proposed device compare to the main structure.

  9. Influence of Vehicle Speed on the Characteristics of Driver's Eye Movement at a Highway Tunnel Entrance during Day and Night Conditions: A Pilot Study.

    Science.gov (United States)

    Qin, Li; Dong, Li-Li; Xu, Wen-Hai; Zhang, Li-Dong; Leon, Arturo S

    2018-04-02

    The aim of this study was to investigate how vehicle speed influences the characteristics of driver's eye movement at highway tunnel entrances during day and night. In this study, six drivers' eye movement data (from 200 m before tunnel entrance to 200 m inside tunnel entrance) under five predetermined vehicle speeds (40, 50, 60, 70 and 80 km/h) in the daytime and three predetermined vehicle speeds (40, 60 and 80 km/h) in the nighttime were recorded using the non-intrusive Dikablis Professional eye-tracking system. Pupil size, the average fixation duration time and the average number of fixation were analyzed and then the influence of the vehicle speed on these parameters was evaluated by means of IBM SPSS Statistics 20.0. The results for pupil size in daytime increased when approaching the tunnel entrance, while as for nighttime, pupil size decreased when approaching the tunnel entrance and then increased after entering the tunnel. The pupil size in daytime has a significant negative correlation with vehicle speed, while the pupil size in nighttime did not show a significant association with vehicle speed. Furthermore, the average fixation duration in daytime increased when entering the tunnel, and had a significant negative correlation with vehicle speed. Also, the average number of fixations in daytime decreased when entering the tunnel and has a significant negative correlation with vehicle speed. However, the average fixation duration and the average number of fixations in nighttime did not show any significant association with vehicle speed. Moreover, limitations and future directions of the study are discussed for the further investigation.

  10. New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal

    OpenAIRE

    Lai, Jinxing; Qiu, Junling; Chen, Jianxun; Fan, Haobo; Wang, Ke

    2015-01-01

    In recent years, with the rapid growth of economy and sharp rise of motor vehicles in China, the pavement skid resistance in tunnel portals has become increasingly important in cold region. However, the deicing salt, snow removal with machine, and other antiskid measures adopted by highway maintenance division have many limitations. To improve the treatment effect, we proposed a new snow-melting approach employing electric heat tracing, in which heating cables are installed in the structural ...

  11. Bow shock specularly reflected ions in the presence of low-frequency electromagnetic waves: a case study

    Directory of Open Access Journals (Sweden)

    K. Meziane

    2004-07-01

    Full Text Available An energetic ion (E≤40 event observed by the CLUSTER/CIS experiment upstream of the Earth's bow shock is studied in detail. The ion event is observed in association with quasi-monochromatic ULF MHD-like waves, which we show modulate the ion fluxes. According to three statistical bow shock position models, the Cluster spacecrafts are located at ~0.5 Re from the shock and the averaged bow shock θBn0 is about ~30°. The analysis of the three-dimensional angular distribution indicates that ions propagating roughly along the magnetic field direction are observed at the onset of the event. Later on, the angular distribution is gyrophase-bunched and the pitch-angle distribution is peaked at α0~θBn0, consistent with the specular reflection production mechanism. The analysis of the waves shows that they are left-handed in the spacecraft frame of reference (right-handed in the solar wind frame and propagate roughly along the ambient magnetic field; we have found that they are in cyclotron-resonance with the field-aligned beam observed just upstream. Using properties of the waves and particles, we explain the observed particle flux-modulation in the context of θBn changes at the shock caused by the convected ULF waves. We have found that the high count rates coincide with particles leaving the shock when θBn angles are less than ~40°, consistent with the specular reflection hypothesis as the production mechanism of ions.

  12. Computer Simulation of Blast Waves in a Tunnel with Sudden Decrease in Cross Section

    Energy Technology Data Exchange (ETDEWEB)

    Glenn, L. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Neuscamman, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-08-22

    The case of an explosion in a tunnel where the blast wave encounters a sudden decrease in cross section is studied with quasi-one-dimensional (1D) and two-dimensional axisymmetric codes (2D) and the results are compared to experimental data. It is found that the numerical results from both codes are in good agreement until the interface at the change in cross section is encountered. Thereafter, however, the peak pressure derived with the codes is found to be significantly higher than the experimental results although the agreement between the 2D result and the experiment improves with increasing distance down the tunnel. Peak pressure and impulse per unit area obtained downstream of the interface with the 1D analysis are found to be substantially higher than with either the experiment or the 2D results. The reason for this is the time delay for the shock reflecting off the (vertical) rigid wall between the inner and outer tunnel radii to interact with the (supersonic) core flow into the decreased cross section. In the 1D case the reflected and transmitted shocks are formed instantaneously across the entire cross section resulting in higher pressure and increased shock speed downstream of the interface.

  13. Shock absorber

    International Nuclear Information System (INIS)

    Nemeth, J.D.

    1981-01-01

    A shock absorber for the support of piping and components in a nuclear power plant is described. It combines a high degree of stiffness under sudden shocks, e.g. seismic disturbances, with the ability to allow for thermal expansion without resistance when so required. (JIW)

  14. Unexpected difficulties in randomizing patients in a surgical trial: A prospective study comparing extracorporeal shock wave lithotripsy with open cholecystectomy

    NARCIS (Netherlands)

    P.W. Plaisier; M.Y. Berger (Marjolein); R.L. van der Hul (René); H.G. Nijs (Huub); R. den Toom (Rene); O.T. Terpstra (Onno); H.A. Bruining (Hajo); S.M. Strasberg (S.)

    1994-01-01

    textabstractShortly after extracorporeal shock wave lithotripsy (ESWL) was introduced as a promising new treatment modality for gallstone disease, a randomized controlled study was performed to assess the cost-effectiveness of ESWL compared to open cholecystectomy, the gold standard. During the

  15. Eye Movement Training and Suggested Gaze Strategies in Tunnel Vision - A Randomized and Controlled Pilot Study.

    Directory of Open Access Journals (Sweden)

    Iliya V Ivanov

    Full Text Available Degenerative retinal diseases, especially retinitis pigmentosa (RP, lead to severe peripheral visual field loss (tunnel vision, which impairs mobility. The lack of peripheral information leads to fewer horizontal eye movements and, thus, diminished scanning in RP patients in a natural environment walking task. This randomized controlled study aimed to improve mobility and the dynamic visual field by applying a compensatory Exploratory Saccadic Training (EST.Oculomotor responses during walking and avoiding obstacles in a controlled environment were studied before and after saccade or reading training in 25 RP patients. Eye movements were recorded using a mobile infrared eye tracker (Tobii glasses that measured a range of spatial and temporal variables. Patients were randomly assigned to two training conditions: Saccade (experimental and reading (control training. All subjects who first performed reading training underwent experimental training later (waiting list control group. To assess the effect of training on subjects, we measured performance in the training task and the following outcome variables related to daily life: Response Time (RT during exploratory saccade training, Percent Preferred Walking Speed (PPWS, the number of collisions with obstacles, eye position variability, fixation duration, and the total number of fixations including the ones in the subjects' blind area of the visual field.In the saccade training group, RTs on average decreased, while the PPWS significantly increased. The improvement persisted, as tested 6 weeks after the end of the training. On average, the eye movement range of RP patients before and after training was similar to that of healthy observers. In both, the experimental and reading training groups, we found many fixations outside the subjects' seeing visual field before and after training. The average fixation duration was significantly shorter after the training, but only in the experimental training

  16. The scanning tunneling microscope

    International Nuclear Information System (INIS)

    Salvan, F.

    1986-01-01

    A newly conceived microscope, based on a pure quantum phenomenon, is an ideal tool to study atom by atom the topography and properties of surfaces. Applications are presented: surface ''reconstruction'' of silicon, lamellar compound study, etc... Spectroscopy by tunnel effect will bring important information on electronic properties; it is presented with an application on silicon [fr

  17. Case study of geostructural prospect of a tunnel by using geophysical methods; Butsuri tansa ni yoru tunnel chisan yosoku to jissai

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, H [Japan Railway Construction Public Corp., Tokyo (Japan); Kawakami, J [Taisei Construction Corp., Tokyo (Japan); Nagasue, I; Hiwatashi, S; Wakuno, M [Oyo Corp., Tokyo (Japan)

    1997-05-27

    A preliminary survey was carried out by combining elastic wave exploration (using a refraction method) and electrical exploration (using a resistivity imaging method) on a long tunnel planned in a granite distributed area. This paper describes a case of verifying geological condition in the area by using a trial survey well and horizontal boring. This tunnel goes through the Seburi mountainous area on the border of Fukuoka Prefecture and Saga Prefecture for a total distance of 12 km. The refraction method and the resistivity imaging method were selected from the necessity of identifying the weathering condition in natural ground, and distributions of fault crush zones and underground water in a section extending 560 m from the well entrance. As a result of comparing the natural ground condition interpreted from the geophysical survey results with the construction records, the fault was detected as a cracked or deformed section in the part where the resistivity value changes abruptly or where the resistivity is low. The tunnel natural ground classification showed a good correspondence with the elastic wave velocities. The largest flooding section showed a good agreement with the section where the resistivity changes suddenly to a lateral direction. Thus, the geological information interpreted from both surveys presented a good correspondence with the construction records, leading to a judgment that the prediction is possible. 3 refs., 4 figs., 5 tabs.

  18. LEP tunnel monorail

    CERN Multimedia

    1985-01-01

    A monorail from CERN's Large Electron Positron collider (LEP, for short). It ran around the 27km tunnel, transporting equipment and personnel. With its 27-kilometre circumference, LEP was the largest electron-positron accelerator ever built and ran from 1989 to 2000. During 11 years of research, LEP's experiments provided a detailed study of the electroweak interaction. Measurements performed at LEP also proved that there are three – and only three – generations of particles of matter. LEP was closed down on 2 November 2000 to make way for the construction of the Large Hadron Collider in the same tunnel.

  19. Large-Scale Experimental and Numerical Study of Blast Acceleration Created by Close-In Buried Explosion on Underground Tunnel Lining

    Directory of Open Access Journals (Sweden)

    Mohamad Reza Soheyli

    2016-01-01

    Full Text Available Despite growing demands for structures in water transportation tunnels, underground installations, subsurface dams, and subterranean channels, there is limited field knowledge about the dynamic behavior of these structures in the face of near-fault earthquakes or impulse excitations. This study conducted a large-scale test on underground tunnel excited by two close-in subsurface explosions. The horizontal and vertical acceleration were recorded on the vertical wall of the tunnel and the free field data including the acceleration on the ground surface at 11-meter distance from the tunnel. The frequency domain analysis of recorded results determined the frequency 961 Hz and 968 Hz for 1.69 kg and 2.76 kg equivalent T.N.T., respectively. Then, finite element analysis results were compared with the test data. The comparisons demonstrated a good correlation and satisfied the field data. Finally, based on numerical modeling, a parametric study was applied to determine the effects of shear wave velocity distance of the crater with respect to the tunnel on impulse response of the tunnel.

  20. STEREO interplanetary shocks and foreshocks

    International Nuclear Information System (INIS)

    Blanco-Cano, X.; Kajdič, P.; Aguilar-Rodríguez, E.; Russell, C. T.; Jian, L. K.; Luhmann, J. G.

    2013-01-01

    We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and θ Bn ∼20-86°. We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr ≤0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at ∼1 AU and have been producing suprathermal particles for a shorter time.

  1. STEREO interplanetary shocks and foreshocks

    Energy Technology Data Exchange (ETDEWEB)

    Blanco-Cano, X. [Instituto de Geofisica, UNAM, CU, Coyoacan 04510 DF (Mexico); Kajdic, P. [IRAP-University of Toulouse, CNRS, Toulouse (France); Aguilar-Rodriguez, E. [Instituto de Geofisica, UNAM, Morelia (Mexico); Russell, C. T. [ESS and IGPP, University of California, Los Angeles, 603 Charles Young Drive, Los Angeles, CA 90095 (United States); Jian, L. K. [NASA Goddard Space Flight Center, Greenbelt, MD and University of Maryland, College Park, MD (United States); Luhmann, J. G. [SSL, University of California Berkeley (United States)

    2013-06-13

    We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and {theta}{sub Bn}{approx}20-86 Degree-Sign . We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr {<=}0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at {approx}1 AU and have been producing suprathermal particles for a shorter time.

  2. A numerical study on bow shocks around the lightning return stroke channel

    International Nuclear Information System (INIS)

    Chen, Qiang; Chen, Bin; Yi, Yun; Chen, P. F.; Mao, Yunfei; Xiong, Run

    2015-01-01

    Bow shock structures are important to various hydrodynamics and magnetohydrodynamics (MHD) phenomena in geophysics and astrophysics. The formation and propagation of bow shocks around the lightning return stroke channel are investigated based on the self-similar motion theory and simulated with a two-dimensional Eulerian finite volume resistive radiation MHD code. In this framework, as verification of theoretical models, the evolving structures of many quantities, such as the plasma density, temperature, pressure, shock velocity, and magnetic field, can be obtained, which present all the characteristics of bow shocks in the lightning return stroke processes. The evolution characteristics and the configuration of the curved return stroke channels, e.g., the non-ideal effects and the scaling laws, are discussed in detail. The results may have applications for some observed features of the return stroke channels and other phenomena in the lightning discharge plasmas

  3. Constrained reaction volume approach for studying chemical kinetics behind reflected shock waves

    KAUST Repository

    Hanson, Ronald K.

    2013-09-01

    We report a constrained-reaction-volume strategy for conducting kinetics experiments behind reflected shock waves, achieved in the present work by staged filling in a shock tube. Using hydrogen-oxygen ignition experiments as an example, we demonstrate that this strategy eliminates the possibility of non-localized (remote) ignition in shock tubes. Furthermore, we show that this same strategy can also effectively eliminate or minimize pressure changes due to combustion heat release, thereby enabling quantitative modeling of the kinetics throughout the combustion event using a simple assumption of specified pressure and enthalpy. We measure temperature and OH radical time-histories during ethylene-oxygen combustion behind reflected shock waves in a constrained reaction volume and verify that the results can be accurately modeled using a detailed mechanism and a specified pressure and enthalpy constraint. © 2013 The Combustion Institute.

  4. A Multi-wavelength Study of an Isolated MSP Bow Shock

    Science.gov (United States)

    Romani, Roger W.; Slane, Patrick; Green, Andrew

    2017-08-01

    PSR J2124-3358 is the only single MSP known to sport an Halpha bow shock. This shock, now also seen in the UV, encloses an unusual X-ray pulsar wind nebula (PWN) with a long off-axis trail. Combining the X-ray and UV images with AAT/KOALA integral field spectroscopy of the Halpha emission, we have an unusually complete picture of the pulsar's (101 km/s transverse) motion and the latitudinal distribution of its wind flux. These images reveal the 3-D orientation of a hard-spectrum PWN jet and a softer equatorial outflow. Within the context of a thin shock model, we can constrain the total energy output of the pulsar and the neutron star moment of inertia. The IFU spectra show extreme Balmer dominance, which also constrains the nature of the UV shock emission.

  5. Evolution of peripheral vs metabolic perfusion parameters during septic shock resuscitation. A clinical-physiologic study

    NARCIS (Netherlands)

    Hernandez, Glenn; Pedreros, Cesar; Veas, Enrique; Bruhn, Alejandro; Romero, Carlos; Rovegno, Maximiliano; Neira, Rodolfo; Bravo, Sebastian; Castro, Ricardo; Kattan, Eduardo; Ince, Can

    2012-01-01

    Purpose: Perfusion assessment during septic shock resuscitation is difficult and usually complex determinations. Capillary refill time (CRT) and central-to-toe temperature difference (Tc-toe) have been proposed as objective reproducible parameters to evaluate peripheral perfusion. The comparative

  6. A review of recent developments in the understanding of transonic shock buffet

    Science.gov (United States)

    Giannelis, Nicholas F.; Vio, Gareth A.; Levinski, Oleg

    2017-07-01

    Within a narrow band of flight conditions in the transonic regime, interactions between shock-waves and intermittently separated shear layers result in large amplitude, self-sustained shock oscillations. This phenomenon, known as transonic shock buffet, limits the flight envelope and is detrimental to both platform handling quality and structural integrity. The severity of this instability has incited a plethora of research to ascertain an underlying physical mechanism, and yet, with over six decades of investigation, aspects of this complex phenomenon remain inexplicable. To promote continual progress in the understanding of transonic shock buffet, this review presents a consolidation of recent investigations in the field. The paper begins with a conspectus of the seminal literature on shock-induced separation and modes of shock oscillation. The currently prevailing theories for the governing physics of transonic shock buffet are then detailed. This is followed by an overview of computational studies exploring the phenomenon, where the results of simulation are shown to be highly sensitive to the specific numerical methods employed. Wind tunnel investigations on two-dimensional aerofoils at shock buffet conditions are then outlined and the importance of these experiments for the development of physical models stressed. Research considering dynamic structural interactions in the presence of shock buffet is also highlighted, with a particular emphasis on the emergence of a frequency synchronisation phenomenon. An overview of three-dimensional buffet is provided next, where investigations suggest the governing mechanism may differ significantly from that of two-dimensional sections. Subsequently, a number of buffet suppression technologies are described and their efficacy in mitigating shock oscillations is assessed. To conclude, recommendations for the direction of future research efforts are given.

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

    OpenAIRE

    Prasnna Jain; A.K. Naithani; T.N. Singh

    2014-01-01

    A 12.24 km long tunnel between Maroshi and Ruparel College is being excavated by tunnel boring machine (TBM) to improve the water supply system of Greater Mumbai, India. In this paper, attempt has been made to establish the relationship between various litho-units of Deccan traps, stability of tunnel and TBM performances during the construction of 5.83 km long tunnel between Maroshi and Vakola. The Maroshi–Vakola tunnel passes under the Mumbai Airport and crosses both runways with an overburd...

  8. Submucosal tunneling using endoscopic submucosal dissection for peritoneal access and closure in natural orifice transluminal endoscopic surgery: a porcine survival study.

    Science.gov (United States)

    Yoshizumi, F; Yasuda, K; Kawaguchi, K; Suzuki, K; Shiraishi, N; Kitano, S

    2009-08-01

    Safe peritoneal access and gastric closure are the most important concerns in the clinical application of natural orifice transluminal endoscopic surgery (NOTES). We aimed to clarify the feasibility of a submucosal tunnel technique using endoscopic submucosal dissection (ESD) for transgastric peritoneal access and subsequent closure for NOTES. Seven female pigs, each weighing about 40 kg were included in the study. The following procedures were performed: (i) after injection of normal saline into the submucosa, the mucosa was cut with a flex knife; (ii) the submucosal layer was dissected using an insulation-tipped electrosurgical knife to make a narrow longitudinal 50-mm submucosal tunnel; (iii) a small incision was made at the end of the tunnel and enlarged with a dilation balloon. After transgastric peritoneoscopy, the mucosal incision site was closed with clips. The following outcome measures were used: (a) evaluation of the technical feasibility of making a submucosal tunnel; (b) clinical monitoring for 7 days; (c) follow-up endoscopy and necropsy; and (d) peritoneal fluid culture. Natural orifice transluminal endoscopic peritoneoscopy with a submucosal tunnel was successfully carried out in all pigs. The pigs recovered well, without signs of peritonitis. Follow-up endoscopy showed healing of mucosal incision sites without open defects. Necropsy revealed no findings of peritonitis, confirming completeness of gastric closure; there was a thin scar in one pig and adhesion of the omentum in six pigs. Peritoneal fluid culture demonstrated no bacterial growth. The submucosal tunnel technique is feasible and effective for transgastric peritoneal access and closure.

  9. Subluxation of the peroneus long tendon in the cuboid tunnel: is it normal or pathologic? An ultrasound and magnetic resonance imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Taylor J. [Charlotte Radiology, Charlotte, NC (United States); Rosenberg, Zehava S.; Ciavarra, Gina; Bencardino, Jenny T. [New York Langone Medical Center / Hospital for Joint Diseases, New York, NY (United States); Velez, Zoraida Restrepo [Cedimed-Dinamica, Medellin (Colombia); Prost, Roberto [Marino Hospital ASL Cagliari, Cagliari (Italy)

    2016-03-15

    To evaluate the position of the peroneus longus (PL) tendon relative to the cuboid tuberosity and cuboid tunnel during ankle dorsiflexion and plantarflexion using ultrasound and MRI. The study population included two groups: 20 feet of 10 asymptomatic volunteers who underwent prospective dynamic ultrasound and 55 ankles found through retrospective review of routine ankle MRI examinations. The location of the PL tendon at the cuboid tuberosity and cuboid tunnel was designated as completely within the tunnel, indeterminate, or subluxed with respect to ankle dorsiflexion and plantarflexion. On dynamic ultrasound, the PL tendon was perched plantar to the cuboid tuberosity in dorsiflexion, and glided to enter the cuboid tunnel distal to the tuberosity in plantarflexion in all 20 feet. On the MRI evaluation, there was a statistically significant difference (p = 0.0006) in the location of the PL tendon between the ankles scanned in dorsiflexion and plantarflexion. Based on our findings on ultrasound and MRI, the PL tendon can glide in and out of the cuboid tunnel along the cuboid tuberosity depending on ankle position. Thus, ''subluxation'' of the tendon as it curves to enter the cuboid tunnel, which to the best of our knowledge has not yet been described, should be recognized as a normal, position-dependent phenomenon and not be reported as pathology. (orig.)

  10. Subluxation of the peroneus long tendon in the cuboid tunnel: is it normal or pathologic? An ultrasound and magnetic resonance imaging study

    International Nuclear Information System (INIS)

    Stone, Taylor J.; Rosenberg, Zehava S.; Ciavarra, Gina; Bencardino, Jenny T.; Velez, Zoraida Restrepo; Prost, Roberto

    2016-01-01

    To evaluate the position of the peroneus longus (PL) tendon relative to the cuboid tuberosity and cuboid tunnel during ankle dorsiflexion and plantarflexion using ultrasound and MRI. The study population included two groups: 20 feet of 10 asymptomatic volunteers who underwent prospective dynamic ultrasound and 55 ankles found through retrospective review of routine ankle MRI examinations. The location of the PL tendon at the cuboid tuberosity and cuboid tunnel was designated as completely within the tunnel, indeterminate, or subluxed with respect to ankle dorsiflexion and plantarflexion. On dynamic ultrasound, the PL tendon was perched plantar to the cuboid tuberosity in dorsiflexion, and glided to enter the cuboid tunnel distal to the tuberosity in plantarflexion in all 20 feet. On the MRI evaluation, there was a statistically significant difference (p = 0.0006) in the location of the PL tendon between the ankles scanned in dorsiflexion and plantarflexion. Based on our findings on ultrasound and MRI, the PL tendon can glide in and out of the cuboid tunnel along the cuboid tuberosity depending on ankle position. Thus, ''subluxation'' of the tendon as it curves to enter the cuboid tunnel, which to the best of our knowledge has not yet been described, should be recognized as a normal, position-dependent phenomenon and not be reported as pathology. (orig.)

  11. demystifying the shock of shocking

    African Journals Online (AJOL)

    (with a pulse), atrial fibrillation and atrial flutter. The energy dose in cardioversion is less (0.5. - 2 J/kg) than in defibrillation (2 - 4 J/kg). In cardioversion the shock is discharged synchronously with the native R wave of the patient. Without synchronisation,. VF can be induced if a shock is delivered during the refractory period ...

  12. Outcomes in Cardiogenic Shock Patients with Extracorporeal Membrane Oxygenation Use: A Matched Cohort Study in Hospitals across the United States

    Directory of Open Access Journals (Sweden)

    Rayan El Sibai

    2018-01-01

    Full Text Available Background. ECMO is increasingly used for patients with critical illnesses. This study examines ECMO use in patients with cardiogenic shock in US hospitals and associated outcomes (mortality, hospital length of stay, and total hospital charges. Methods. A matched cohort retrospective study was conducted using the 2013 Nationwide Emergency Department Sample. Cardiogenic shock visits were matched (1 : 1 and compared based on ECMO use. Results. Patients with ECMO (N=802 were compared to patients without ECMO (N=805. Mortality was higher in the ECMO group (48.9% versus 4.0%, p < 0.001. Visits with ECMO use also had higher average hospital charges ($580,065.8 versus $156,436.5, p < 0.001 and average hospital LOS (21.3 versus 11.6 days, p < 0.001. After adjusting for confounders, mortality (OR = 8.52 (95% CI: 2.84–25.58 and charges (OR = 1.03 (95% CI: 1.02–1.05 remained higher in the ECMO group, while LOS was similar (OR = 1.01 (95% CI: 0.99–1.02. Conclusions. Patients with cardiogenic shock who underwent ECMO had increased mortality and higher cost of care without significant increase in LOS when compared to patients with cardiogenic shock without ECMO use. Prospective evaluation of this observed association is needed to improve outcomes and resources’ utilization further.

  13. Bimetallic Catalysts and Platinum Surfaces Studied by X-ray Absorption Spectroscopy and Scanning Tunnelling Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roenning, Magnus

    2000-07-01

    Bimetallic catalyst systems used in Fischer-Tropsch synthesis (Co-Re/Al{sub 2}O{sub 3}) and in the naphtha reforming process (Pt-Re/Al{sub 2}O{sub 3}) have been studied in situ using X-ray absorption spectroscopy (EXAFS). Additionally, the adsorption of ethene on platinum single crystal surfaces has been investigated using scanning tunnelling microscopy. In situ EXAFS at the cobalt K absorption edge have been carried out at 450{sup o}C on the hydrogen reduction of a rhenium-promoted Co{sub 3}O{sub 4}/Al{sub 2}O{sub 3} catalyst. Reductions carried out using 100% hydrogen and 5% hydrogen in helium gave different results. Whereas the reduction using dilute hydrogen leads to bulk-like metallic cobalt particles (hcp or fcc), reaction with pure hydrogen yields a more dispersed system with smaller cobalt metal particles (< 40 A). The results are rationalised in terms of different degrees of reoxidation of cobalt by the higher and lower concentrations of water generated during the reduction of cobalt oxide by 100% and 5% hydrogen, respectively. Additionally, in both reduction protocols a small fraction (3 -4 wt%) of the cobalt content is randomly dispersed over the tetrahedral vacancies of the alumina support. This dispersion occurs during reduction and not calcination. The cobalt in these sites cannot be reduced at 450 {sup o}C. The local environments about the rhenium atoms in Co-Re/{gamma}-A1{sub 2}O{sub 3} catalyst after different reduction periods have been studied by X-ray absorption spectroscopy. A bimetallic catalyst containing 4.6 wt% cobalt and 2 wt% rhenium has been compared with a corresponding monometallic sample with 2 wt% rhenium on the same support. The rhenium L{sub III} EXAFS analysis shows that bimetallic particles are formed after reduction at 450{sup o}C with the average particle size being 10-15 A. Rhenium is shown to be reduced at a later stage than cobalt. The fraction of cobalt atoms entering the support obstructs the access to the support for the

  14. Grain destruction in interstellar shocks

    International Nuclear Information System (INIS)

    Seab, C.G.; Shull, J.M.

    1984-01-01

    One of the principal methods for removing grains from the Interstellar Medium is to destroy them in shock waves. Previous theoretical studies of shock destruction have generally assumed only a single size and type of grain; most do not account for the effect of the grain destruction on the structure of the shock. Earlier calculations have been improved in three ways: first, by using a ''complete'' grain model including a distribution of sizes and types of grains; second, by using a self-consistent shock structure that incorporates the changing elemental depletions as the grains are destroyed; and third, by calculating the shock-processed ultraviolet extinction curves for comparison with observations. (author)

  15. Supramolecular tunneling junctions

    NARCIS (Netherlands)

    Wimbush, K.S.

    2012-01-01

    In this study a variety of supramolecular tunneling junctions were created. The basis of these junctions was a self-assembled monolayer of heptathioether functionalized ß-cyclodextrin (ßCD) formed on an ultra-flat Au surface, i.e., the bottom electrode. This gave a well-defined hexagonally packed

  16. IPTS [Integrated Pressurized-Thermal-Shock] study for H.B. Robinson (HBR-HYPO)

    International Nuclear Information System (INIS)

    Cheverton, R.D.

    1990-01-01

    A primary purpose of the US Nuclear Regulatory Commission (NRC) Integrated Pressurized-Thermal-Shock (IPTS) Program, completed in 1985, was to develop an integrated probabilistic approach for evaluating pressurized water reactor (PWR) pressure vessel integrity; and the scope included the application of the methodology to three ''high risk'' PWR plants. The three plants selected were Oconee Unit 1, Calvert Cliffs Unit 1, and HBRobinson Unit 2 (HBR-2); and the plant studies were conducted in that order. As a result of this sequence and the developmental nature of the program, the HBR-2 study was the more complete and state-of-the-art. However, by the time the HBR-2 study was conducted, a reevaluation of vessel chemistry and reference nil-ductility transition temperature (RT NDT ) had indicated relatively low concentrations of copper and nickel and low values of initial RT NDT (RT NDT 0 ), resulting in very low probabilities of failure. Thus, for illustrative purposes, copper, nickel, and RT NDT 0 were increased so that RT NDT (2σ) = 270 degree F for the critical weld at 32 EFPY. This value of RT NDT corresponds, of course, to the NRC PTS-Rule screening criteria (10 CFR 5.61). This hypothetical ''plant'' was referred to as HBR-HYPO, and it was identical to HBR-2 in every respect except for the concentrations of copper and nickel and the value of RT NDT 0 for the welds. 3 refs

  17. Shock tube/laser absorption studies of the decomposition of methyl formate

    KAUST Repository

    Ren, Wei; Lam, Kingyiu; Pyun, Sunghyun; Farooq, Aamir; Davidson, David Frank; Hanson, Ronald Kenneth

    2013-01-01

    Reaction rate coefficients for the major high-temperature methyl formate (MF, CH3OCHO) decomposition pathways, MF → CH3OH + CO (1), MF →CH2O+CH2O (2), and MF→ CH4 + CO2 (3), were directly measured in a shock tube using laser absorption of CO (4.6 μm), CH2O (306 nm) and CH4 (3.4 μm). Experimental conditions ranged from 1202 to 1607 K and 1.36 to 1.72 atm, with mixtures varying in initial fuel concentration from 0.1% to 3% MF diluted in argon. The decomposition rate coefficients were determined by monitoring the formation rate of each target species immediately behind the reflected shock waves and modeling the species time-histories with a detailed kinetic mechanism [12]. The three measured rate coefficients can be well-described using two-parameter Arrhenius expressions over the temperature range in the present study: k1 = 1.1 × 1013 exp(-29556/T, K) s -1, k2 = 2.6 × 1012 exp(-32052/T, K) s-1, and k3 = 4.4 × 1011 exp(-29 078/T, K) s-1, all thought to be near their high-pressure limits. Uncertainties in the k1, k2 and k3 measurements were estimated to be ±25%, ±35%, and ±40%, respectively. We believe that these are the first direct high-temperature rate measurements for MF decomposition and all are in excellent agreement with the Dooley et al. [12] mechanism. In addition, by also monitoring methanol (CH3OH) and MF concentration histories using a tunable CO2 gas laser operating at 9.67 and 9.23 μm, respectively, all the major oxygen-carrying molecules were quantitatively detected in the reaction system. An oxygen balance analysis during MF decomposition shows that the multi-wavelength laser absorption strategy used in this study was able to track more than 97% of the initial oxygen atoms in the fuel. © 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

  18. Specific Metabolome Profile of Exhaled Breath Condensate in Patients with Shock and Respiratory Failure: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Brice Fermier

    2016-09-01

    Full Text Available Background: Shock includes different pathophysiological mechanisms not fully understood and remains a challenge to manage. Exhaled breath condensate (EBC may contain relevant biomarkers that could help us make an early diagnosis or better understand the metabolic perturbations resulting from this pathological situation. Objective: we aimed to establish the metabolomics signature of EBC from patients in shock with acute respiratory failure in a pilot study. Material and methods: We explored the metabolic signature of EBC in 12 patients with shock compared to 14 controls using LC-HRMS. We used a non-targeted approach, and we performed a multivariate analysis based on Orthogonal Partial Least Square-Discriminant Analysis (OPLS-DA to differentiate between the two groups of patients. Results: We optimized the procedure of EBC collection and LC-HRMS detected more than 1000 ions in this fluid. The optimization of multivariate models led to an excellent model of differentiation for both groups (Q2 > 0.4 after inclusion of only 6 ions. Discussion and conclusion: We validated the procedure of EBC collection and we showed that the metabolome profile of EBC may be relevant in characterizing patients with shock. We performed well in distinguishing these patients from controls, and the identification of relevant compounds may be promising for ICC patients.

  19. Enhanced Scattering of Diffuse Ions on Front of the Earth's Quasi-Parallel Bow Shock: a Case Study

    Science.gov (United States)

    Kis, A.; Matsukiyo, S.; Otsuka, F.; Hada, T.; Lemperger, I.; Dandouras, I. S.; Barta, V.; Facsko, G. I.

    2017-12-01

    In the analysis we present a case study of three energetic upstream ion events at the Earth's quasi-parallel bow shock based on multi-spacecraft data recorded by Cluster. The CIS-HIA instrument onboard Cluster provides partial energetic ion densities in 4 energy channels between 10 and 32 keV.The difference of the partial ion densities recorded by the individual spacecraft at various distances from the bow shock surface makes possible the determination of the spatial gradient of energetic ions.Using the gradient values we determined the spatial profile of the energetic ion partial densities as a function of distance from the bow shock and we calculated the e-folding distance and the diffusion coefficient for each event and each ion energy range. Results show that in two cases the scattering of diffuse ions takes place in a normal way, as "by the book", and the e-folding distance and diffusion coefficient values are comparable with previous results. On the other hand, in the third case the e-folding distance and the diffusion coefficient values are significantly lower, which suggests that in this case the scattering process -and therefore the diffusive shock acceleration (DSA) mechanism also- is much more efficient. Our analysis provides an explanation for this "enhanced" scattering process recorded in the third case.

  20. Offshore and onshore wind turbine wake meandering studied in an ABL wind tunnel

    DEFF Research Database (Denmark)

    Barlas, Emre; Buckingham, Sophia; Glabeke, Gertjan

    2015-01-01

    Scaled wind turbine models have been installed in the VKI L1-B atmospheric boundary layer wind tunnel at offshore and onshore conditions. Time-resolved measurements were carried out with three component hot wire anemometry and stereo-PIV in the middle vertical plane of the wake up to eleven turbine...... diameter downstream. The results show an earlier wake recovery for the onshore case. The effect of inflow conditions and the wind turbine’s working conditions on wake meandering was investigated. Wake meandering was detected by hot wire anemometry through a low frequency peak in the turbulent power...

  1. Quantum tunneling of magnetization in molecular nanomagnet Fe8 studied by NMR

    International Nuclear Information System (INIS)

    Maegawa, Satoru; Ueda, Miki

    2003-01-01

    Magnetization and NMR measurements have been performed for single crystals of molecular magnet Fe8. The field and temperature dependences of magnetization below 25 K are well described in terms of the isolated clusters with the total spin S=10. The stepwise recoveries of 1 H-NMR signals at the level crossing fields caused by the resonant quantum tunneling of magnetization were observed below 400 mK. The recovery of the NMR signals are explained by the fluctuation caused by the transition between the energy states of Fe magnetizations governed by Landau-Zener quantum transitions

  2. BIM Methodology Approach to Infrastructure Design: Case Study of Paniga Tunnel

    Science.gov (United States)

    Osello, Anna; Rapetti, Niccolò; Semeraro, Francesco

    2017-10-01

    Nowadays, the implementation of Building Information Modelling (BIM) in civil design represent a new challenge for the AECO (Architecture, Engineering, Construction, Owner and Operator) world, which will involve the interest of many researchers in the next years. It is due to the incentives of Public Administration and European Directives that aim to improve the efficiency and to enhance a better management of the complexity of infrastructure projects. For these reasons, the goal of this research is to propose a methodology for the use of BIM in a tunnel project, analysing the definition of a correct level of detail (LOD) and the possibility to share information via interoperability for FEM analysis.

  3. Epitaxial clusters studied by synchrotron x-ray diffraction and scanning tunneling microscopy

    DEFF Research Database (Denmark)

    Nielsen, M.; Feidenhans'l, R.; Rasmussen, F.B.

    1998-01-01

    Nanoscale clusters are often formed during heteroepitaxial crystal growth. Misfit between the lattice parameter of the substrate and the adsorbate stimulates the formation of regular clusters with a characteristic size. The well-known "hut-clusters" formed during the growth of Ge on Si(001) are a...... similar to the "hut clusters". We demonstrate that X-ray diffraction in combination with scanning tunneling microscopy can be used to determine the fundamental properties of such clusters. (C) 1998 Elsevier Science B.V. All rights reserved....

  4. Carpal Tunnel Syndrome

    Science.gov (United States)

    ... a passing cramp? It could be carpal tunnel syndrome. The carpal tunnel is a narrow passageway of ... three times more likely to have carpal tunnel syndrome than men. Early diagnosis and treatment are important ...

  5. Preparation of theoretical scanning tunneling microscope images of adsorbed molecules: a theoretical study of benzene on the Cu(110) surface

    International Nuclear Information System (INIS)

    Shapter, J.G.; Rogers, B.L.; Ford, M.J.

    2003-01-01

    Full text: Since its development in 1982, the Scanning Tunneling Microscope (STM) has developed into a powerful tool for the study of surfaces and adsorbates. However, the utility of the technique can be further enhanced through the development of techniques for generating theoretical STM images. This is particularly true when studying molecules adsorbed on a substrate, as the results are often interpreted superficially due to an inadequate understanding of the orbital overlap probed in the experiment. A method of preparing theoretical scanning tunneling microscope (STM) images using comparatively inexpensive desktop computers and the commercially available CRYSTAL98 package is presented through a study of benzene adsorbed on the Cu(110) surface. Density Functional Theory (DFT) and Hartree-Fock (HF) methods are used to model clean Cu(110) slabs of various thicknesses and to simulate the adsorption of benzene onto these slabs. Eight possible orientations of benzene on the Cu(110) surface are proposed, and the optimum orientation according to the calculations is presented. Theoretical STM images of the Cu(110) surface and benzene adsorbed on the Cu(110) surface are compared with experimental STM images of the system from a published study. Significant differences are observed and are examined in detail

  6. Cultural adaptation of the Michigan Hand Outcomes Questionnaire in patients with Carpal Tunnel Syndrome: A Turkish version study

    Directory of Open Access Journals (Sweden)

    Ilker Ilhanli

    2015-03-01

    Full Text Available Objective: Cultural adaptations of the questionnaires are important for easy use. We aimed to assess the reliability and validity of the Turkish Version of the Michigan Hand Outcomes Questionnaire in patients with Carpal Tunnel Syndrome. Methods: To assess test-retest reliability, the Turkish “Michigan Hand Outcomes Questionnaire” and “Disabilities of Arm, Shoulder and Hand” questionnaires were answered by patients and controls and were repeated a week later. For testing internal consistency, the Cronbach's alpha test was used. For testing validity, correlations between the subscales of the “Michigan Hand Outcomes Questionnaire” and “Disabilities of Arm, Shoulder and Hand” questionnaire were measured in patient groups. One hundred patients with idiopathic Carpal Tunnel Syndrome and 50 healthy participants were included in the study. Results: In test-retest reliability, intraclass correlations of the subscales of the “Michigan Hand Outcomes Questionnaire” were high. Cronbach's alphas were found to be high in all subscales. There was no significant correlation between asthetics and pain scales. We found significant differences between patients and controls regarding all subscales of the “Michigan Hand Outcomes Questionnaire”. Correlations between subscales of the “Michigan Hand Outcomes Questionnaire” and “Disabilities of Arm, Shoulder and Hand” questionnaire were significant. We found no difference between one-hand effected and two-hand effected patients, in terms of the “Michigan Hand Outcomes Questionnaire”, “Disabilities of Arm, Shoulder and Hand” questionnaire Function/Symptom and Work average scores. Conclusion: This study showed that the Turkish version of the “Michigan Hand Outcomes Questionnaire” is reliable and valid and can be used in Turkish patients with Carpal Tunnel Syndrome because it is comprehensible and practicable

  7. Carpal tunnel syndrome assessed with diffusion tensor imaging: Comparison with electrophysiological studies of patients and healthy volunteers

    International Nuclear Information System (INIS)

    Wang, Chien-Kuo; Jou, I-Ming; Huang, Han-Wei; Chen, Pei-Yin; Tsai, Hong-Ming; Liu, Yi-Sheng; Lin, Chou-Ching K.

    2012-01-01

    The main goal of this study was to investigate the applicability of parameters derived from diffusion tension imaging (DTI) in diagnosing carpal tunnel syndrome (CTS). Forty subjects were recruited, of which 19 were normal controls and 21 belonged to the CTS group. DTI of median nerves evaluated at 4 levels of the wrist (distal radius, pisiform bone, middle portion of the carpal tunnel, and hamate bone) and conventional MRI of the wrist was performed in normal and CTS subjects in two finger postures (extension and flexion). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were derived from DTI, and parameters related to abnormal hyperintensity of the median nerve were derived from conventional MRI. Electrophysiological tests, including nerve conduction velocity and F wave were also performed for comparison. The results of FA and ADC measurements did not depend on the measuring location and finger posture. Mean FA was decreased while mean ADC was increased by CTS. FA and ADC at the middle portion of the carpal tunnel was 0.47 ± 0.05 and 1.37 ± 0.12 (×10 −3 mm 2 /s) for the control group and 0.42 ± 0.04 and 1.50 ± 0.15 (×10 −3 mm 2 /s) for the CTS group, respectively. The linear correlations of FA and ADC versus electrophysiological indicators of CTS were significant (R 2 ranged from 0.09 to 0.36), indicating FA and ADC from DTI had significant correlation with the existence and severity of CTS.

  8. [Applied studies of structured triglycerides for parenteral nutrition in severe hemorrhagic shock patients after resuscitation].

    Science.gov (United States)

    Su, Mao-sheng; He, Lei; Liu, Zhi-wei; Ma, Huan-xian; Zhao, Qing-hua; Zhang, Wen-zhi

    2012-03-27

    To evaluate the effects of structured triglycerides in parenteral nutrition versus a physical medium-chain triglycerides (MCT)/long-chain triglycerides (LCT) mixture on severe hemorrhagic shock patients after resuscitation. In a randomized trial, we studied 20 critical patients with a total blood loss of over 3000 ml perioperatively and/or intraoperatively. The use of triglycerides started from Day 3 postoperation and parenteral nutrition lasted for no less than 5 days. They were allocated to receive one of two nutrition regiments: structured triglycerides in Group A (n = 10) and MCT/LCT in Group B (n = 10). There were no significant differences of general conditions in two groups. Before the start of parenteral nutrition (d0), d1 d3 and d5 after start of infusion, the following parameters were measured: hemoglobin (Hb), platelet count (Plt), alanine aminotransferase (ALT), total bilirubin (TB), direct bilirubin (DB), serum triglycerides (TG), prealbumin (PA) and transferrin (TF). And mean artery pressure (MAP), heart rate (HR) and central vein pressure (CVP) were also recorded at the same time-points. Then the post-TG changes of the above data were compared in both groups. After the use of triglycerides, there were no significant differences of MAP, HR, CVP, Hb and Plt in both groups (P > 0.05). At D3 and D5, the serum levels of TG ((2.1 ± 0.4) vs (1.6 ± 0.6) mg/L, (2.3 ± 0.7) vs (1.5 ± 0.3) mg/L) and alanine aminotransferase ((133 ± 58) vs (97 ± 26) U/L; (116 ± 48) vs (77 ± 31) U/L) were significantly higher in Group B versus those receiving structured triglycerides in Group A (P 0.05). The serum levels of such nutrition markers as PA ((195 ± 55) vs (166 ± 55) mg/L,(245 ± 53) vs (195 ± 58) mg/L) and TF ((2.6 ± 0.5) vs (2.5 ± 0.6) g/L, (3.3 ± 0.8) vs (2.9 ± 0.6) g/L)were significantly higher in Group A than those in Group B (P synthesis and hepatocyte protection, structured triglycerides in parenteral nutrition is advantageous to standard MCT

  9. Hypovolemic shock

    Science.gov (United States)

    ... the person's position unless they are in immediate danger. Do not give fluids by mouth. If person ... the patient with shock. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine . 25th ed. Philadelphia, PA: ...

  10. Spin-polarized scanning tunneling microscopy and spectroscopy study of chromium on a Cr(001) surface.

    Science.gov (United States)

    Lagoute, J; Kawahara, S L; Chacon, C; Repain, V; Girard, Y; Rousset, S

    2011-02-02

    Several tens of chromium layers were deposited at 250 °C on a Cr(001) surface and investigated by spin-polarized scanning tunneling microscopy (SP-STM), Auger electron spectroscopy (AES) and scanning tunneling spectroscopy (STS). Chromium is found to grow with a mound-like morphology resulting from the stacking of several monolayers which do not uniformly cover the whole surface of the substrate. The terminal plane consists of an irregular array of Cr islands with lateral sizes smaller than 20 × 20 nm(2). Combined AES and STS measurements reveal the presence of a significant amount of segregants prior to and after deposition. A detailed investigation of the surface shows that it consists of two types of patches. Thanks to STS measurements, the two types of area have been identified as being either chromium pure or segregant rich. SP-STM experiments have evidenced that the antiferromagnetic layer coupling remains in the chromium mounds after deposition and is not significantly affected by the presence of the segregants.

  11. Efficacy of paraffin wax bath for carpal tunnel syndrome: a randomized comparative study

    Science.gov (United States)

    Ordahan, Banu; Karahan, Ali Yavuz

    2017-12-01

    Carpal tunnel syndrome (CTS) is the most frequently diagnosed neuropathy of upper extremity entrapment neuropathies. We aimed to investigate the effectiveness of paraffin therapy in patients with CTS. Seventy patients diagnosed with mild or moderate CTS were randomly divided into two groups as splint treatment (during the night and day time as much as possible for 3 weeks) alone and splint (during the night and day time as much as possible for 3 weeks) + paraffin treatment (five consecutive days a week for 3 weeks). Clinical and electrophysiological assessments were performed before and 3 weeks after treatment. The patients were assessed by using visual analog scale (VAS) for pain, electroneuromyography (ENMG), and Boston Carpal Tunnel Syndrome Questionnaire (BCTSQ). The significant improvement was found in VAS scores in both groups when compared with pretreatment values ( p 0.05), whereas a significant improvement was noted in the BCTQ symptom severity scale score in the splint group ( p 0.05), and the difference in these parameters between the groups was statistically significant ( p Paraffin treatment with splint increases the recovery in functional and electrophysiological parameters.

  12. Shock absorber

    International Nuclear Information System (INIS)

    Housman, J.J.

    1978-01-01

    A shock absorber is described for use in a hostile environment at the end of a blind passage for absorbing impact loads. The shock absorber includes at least one element which occupies the passage and which is comprised of a porous brittle material which is substantially non-degradable in the hostile environment. A void volume is provided in the element to enable the element to absorb a predetermined level of energy upon being crushed due to impact loading

  13. Predictive value of low tube voltage and dual-energy CT for successful shock wave lithotripsy: an in vitro study.

    Science.gov (United States)

    Largo, Remo; Stolzmann, Paul; Fankhauser, Christian D; Poyet, Cédric; Wolfsgruber, Pirmin; Sulser, Tullio; Alkadhi, Hatem; Winklhofer, Sebastian

    2016-06-01

    This study investigates the capabilities of low tube voltage computed tomography (CT) and dual-energy CT (DECT) for predicting successful shock wave lithotripsy (SWL) of urinary stones in vitro. A total of 33 urinary calculi (six different chemical compositions; mean size 6 ± 3 mm) were scanned using a dual-source CT machine with single- (120 kVp) and dual-energy settings (80/150, 100/150 Sn kVp) resulting in six different datasets. The attenuation (Hounsfield Units) of calculi was measured on single-energy CT images and the dual-energy indices (DEIs) were calculated from DECT acquisitions. Calculi underwent SWL and the number of shock waves for successful disintegration was recorded. The prediction of required shock waves regarding stone attenuation/DEI was calculated using regression analysis (adjusted for stone size and composition) and the correlation between CT attenuation/DEI and the number of shock waves was assessed for all datasets. The median number of shock waves for successful stone disintegration was 72 (interquartile range 30-361). CT attenuation/DEI of stones was a significant, independent predictor (P waves with the best prediction at 80 kVp (β estimate 0.576) (P waves ranged between ρ = 0.31 and 0.68 showing the best correlation at 80 kVp (P < 0.001). The attenuation of urinary stones at low tube voltage CT is the best predictor for successful stone disintegration, being independent of stone composition and size. DECT shows no added value for predicting the success of SWL.

  14. Design of a Facility for Studying Shock-Cell Noise on Single and Coaxial Jets

    Directory of Open Access Journals (Sweden)

    Daniel Guariglia

    2018-03-01

    Full Text Available Shock-cell noise occurs in aero-engines when the nozzle exhaust is supersonic and shock-cells are present in the jet. In commercial turbofan engines, at cruise, the secondary flow is often supersonic underexpanded, with the formation of annular shock-cells in the jet and consequent onset of shock-cell noise. This paper aims at describing the design process of the new facility FAST (Free jet AeroacouSTic laboratory at the von Karman Institute, aimed at the investigation of the shock-cell noise phenomenon on a dual stream jet. The rig consists of a coaxial open jet, with supersonic capability for both the primary and secondary flow. A coaxial silencer was designed to suppress the spurious noise coming from the feeding lines. Computational fluid dynamics (CFD simulations of the coaxial jet and acoustic simulations of the silencer have been carried out to support the design choices. Finally, the rig has been validated by performing experimental measurements on a supersonic single stream jet and comparing the results with the literature. Fine-scale PIV (Particle Image Velocimetry coupled with a microphone array in the far field have been used in this scope. Preliminary results of the dual stream jet are also shown.

  15. Numerical study of shock waves in non-ideal magnetogasdynamics (MHD

    Directory of Open Access Journals (Sweden)

    Addepalli Ramu

    2016-01-01

    Full Text Available One-dimensional unsteady adiabatic flow of strong converging shock waves in cylindrical or spherical symmetry in MHD, which is propagating into plasma, is analyzed. The plasma is assumed to be non-ideal gas whose equation of state is of Mie–Gruneisen type. Suitable transformations reduce the governing equations into ordinary differential equations of Poincare type. In the present work, McQueen and Royce equations of state (EOS have been considered with suitable material constants and the spherical and cylindrical cases are worked out in detail to investigate the behavior and the influence on the shock wave propagation by energy input and β(ρ/ρ0, the measure of shock strength. The similarity solution is valid for adiabatic flow as long as the counter pressure is neglected. The numerical technique applied in this paper provides a global solution to the implosion problem for the flow variables, the similarity exponent α for different Gruneisen parameters. It is shown that increasing β(ρ/ρ0 does not automatically decelerate the shock front but the velocity and pressure behind the shock front increases quickly in the presence of the magnetic field and decreases slowly and become constant. This becomes true whether the piston is accelerated, is moving at constant speed or is decelerated. These results are presented through the illustrative graphs and tables. The magnetic field effects on the flow variables through a medium and total energy under the influence of strong magnetic field are also presented.

  16. Modeling Acute Traumatic Hemorrhagic Shock Injury: Challenges and Guidelines for Preclinical Studies.

    Science.gov (United States)

    Tremoleda, Jordi L; Watts, Sarah A; Reynolds, Penny S; Thiemermann, Christoph; Brohi, Karim

    2017-12-01

    Trauma is responsible for a large proportion of the world's burden of disease, and is by far the biggest killer of young adults. Hemorrhage is the leading cause of preventable death and its effects are directly correlated with the incidence multi-organ failure in survivors. Trauma research is challenging due to patient heterogeneity, limited randomized controlled trials, and in vitro studies that fail to mimic the systemic injury response. Preclinical research remains essential for mechanistic and therapeutic discovery. Yet modeling the multifaceted nature of traumatic injury poses important experimental and welfare challenges associated with the onset of injury and prehospital and intra-operative care, the limited inter-species validation of coagulation profiles, the use of anesthesia/analgesia, and its impact on the systemic response to trauma; and the challenge of sustaining intensive care in recovery models. Proper model selection depends on the purpose of a given model and the criteria by which the experimental readouts will be clinically relevant. Such complexity warrants further refinement of experimental methodology and outcome measures to improve its clinical efficacy, while ensuring animal well-being. We review the experimental methodologies currently used for modeling traumatic hemorrhagic shock and addressing their impact on clinical translation. The aim of the review is to improve transparency and form a consensus when reporting methodology in trauma modeling.

  17. [Radial shock wave therapy in calcifying tendinitis of the rotator cuff--a prospective study].

    Science.gov (United States)

    Magosch, P; Lichtenberg, S; Habermeyer, P

    2003-01-01

    The aim of the study is to evaluate the influence of radial shock wave therapy (RSWT) on the course of calcifying tendinitis of the rotator cuff. 35 patients with a mean age of 47.5 years suffering from calcifying tendinitis stage Gaertner 2 with a mean size of 16.6 mm in typical location (true-ap view) for a mean of 28 months were treated by low-energy RSWT three times. The acromio-humeral distance averaged 10.4 mm measured at the true-ap view. All patients were clinically and radiologically followed-up at 4 weeks, 3, 6 and 12 months after the last treatment. The Constant score improved significantly (p energy RSWT leads within the first 4 weeks to a significant pain relief and an improvement of shoulder function. In consideration of the long history, the size and the spontaneous resorption rate of the calcific deposit, an inductive effect of RSWT on the resorption of the calcific deposit can be assumed.

  18. An Experimental Study on Micro Clinching of Metal Foils with Cutting by Laser Shock Forming.

    Science.gov (United States)

    Wang, Xiao; Li, Cong; Ma, Youjuan; Shen, Zongbao; Sun, Xianqing; Sha, Chaofei; Gao, Shuai; Li, Liyin; Liu, Huixia

    2016-07-13

    This paper describes a novel technique for joining similar and dissimilar metal foils, namely micro clinching with cutting by laser shock forming. A series of experiments were conducted to study the deformation behavior of single layer material, during which many important process parameters were determined. The process window of the 1060 pure aluminum foils and annealed copper foils produced by micro clinching with cutting was analyzed. Moreover, similar material combination (annealed copper foils) and dissimilar material combination (1060 pure aluminum foils and 304 stainless steel foils) were successfully achieved. The effect of laser energy on the interlock and minimum thickness of upper foils was investigated. In addition, the mechanical strength of different material combinations joined by micro clinching with cutting was measured in single lap shearing tests. According to the achieved results, this novel technique is more suitable for material combinations where the upper foil is thicker than lower foil. With the increase of laser energy, the interlock increased while the minimum thickness of upper foil decreased gradually. The shear strength of 1060 pure aluminum foils and 304 stainless steel foils combination was three times as large as that of 1060 pure aluminum foils and annealed copper foils combination.

  19. An Experimental Study on Micro Clinching of Metal Foils with Cutting by Laser Shock Forming

    Directory of Open Access Journals (Sweden)

    Xiao Wang

    2016-07-01

    Full Text Available This paper describes a novel technique for joining similar and dissimilar metal foils, namely micro clinching with cutting by laser shock forming. A series of experiments were conducted to study the deformation behavior of single layer material, during which many important process parameters were determined. The process window of the 1060 pure aluminum foils and annealed copper foils produced by micro clinching with cutting was analyzed. Moreover, similar material combination (annealed copper foils and dissimilar material combination (1060 pure aluminum foils and 304 stainless steel foils were successfully achieved. The effect of laser energy on the interlock and minimum thickness of upper foils was investigated. In addition, the mechanical strength of different material combinations joined by micro clinching with cutting was measured in single lap shearing tests. According to the achieved results, this novel technique is more suitable for material combinations where the upper foil is thicker than lower foil. With the increase of laser energy, the interlock increased while the minimum thickness of upper foil decreased gradually. The shear strength of 1060 pure aluminum foils and 304 stainless steel foils combination was three times as large as that of 1060 pure aluminum foils and annealed copper foils combination.

  20. Kajian Konsep Kebijakan Infrastruktur Strategis untuk Pengendali Banjir Jakarta (Studi Kasus Giant Sea Wall dan Multi Purpose Deep Tunnel

    Directory of Open Access Journals (Sweden)

    Agung Wiyono

    2016-04-01

    Full Text Available Floods is a-must to be faced agenda by the government. However, the development of flood control infrastructure has not overcome floods in Jakarta. This study discusses the concept of policy plans and flood management infrastructure of sea wall and deep tunnels, simulation of decision-making in organizations with public policy theory: The Garbage Can a Model of Organizational Choice. Using comparative study, authors compare both infrastructure in the technical aspects, economic, environmental, social, and political, through qualitative and quantitative approaches to determine the most influential aspects. Analysis processed by the Analytical Hierarchy Process, Expert Choice and SPSS. The results showed difference in the consideration of the decision-making infrastructure. From the simulation of both types of infrastructure elections by using AHP, Expert Choice questionnaire and analysis, selected infrastructure is deep tunnel. In the analysis appears that the political aspect is regarded as the most influential aspect in decision making infrastructure. Which is not appropriate when a solution is needed to solve technical issues but politics was the main consideration and make solution becomes less relevant. This is proved by the simulation model of decision-making with a Garbage Can Theory of Organizational Choice models, where the simulation results show that the obtained solution for their supervision more than the obtained solution for their joint resolution.

  1. Intracardiac electrocardiographic assessment of precordial TASER shocks in human subjects: A pilot study.

    Science.gov (United States)

    Stopyra, Jason P; Winslow, James E; Fitzgerald, David M; Bozeman, William P

    2017-11-01

    Case reports of cardiac arrest in temporal proximity to Conducted Electrical Weapon(CEW) exposure raise legitimate concerns about this as a rare possibility. In this pilot study, we respectfully navigate the oversight and regulatory hurdles and demonstrate the intra-shock electrocardiographic effects of an intentional transcardiac CEW discharge using subcutaneous probes placed directly across the precordium of patients with a previously implanted intracardiac EKG sensing lead. Adults scheduled to undergo diagnostic EP studies or replacement of an implanted cardiac device were enrolled. Sterile subcutaneous electrodes were placed at the right sternoclavicular junction and the left lower costal margin at the midclavicular line. A standard police issue TASER Model X26 CEW was attached to the subcutaneous electrodes and a 5 s discharge was delivered. Continuous surface and intracardiac EKG monitoring was performed. A total of 157 subjects were reviewed for possible inclusion and 21 were interviewed. Among these, 4 subjects agreed and completed the study protocol. All subjects tolerated the 5 s CEW discharge without clinical complications. There were no significant changes in mean heart rate or blood pressure. Interrogation of the devices after CEW discharge revealed no ventricular pacing, dysrhythmias, damage or interference with the implanted devices. In this pilot study, we have successfully navigated the regulatory hurdles and demonstrated the feasibility of performing intracardiac EKG recording during intentional precordial CEW discharges in humans. While no CEW-associated dysrhythmias were noted, the size of this preliminary dataset precludes making conclusions about the risk of such events. Larger studies are warranted and should consider exploring variations of the CEW electrode position in relation to the cardiac silhouette. Copyright © 2017. Published by Elsevier Ltd.

  2. Tunneling path toward spintronics

    International Nuclear Information System (INIS)

    Miao Guoxing; Moodera, Jagadeesh S; Muenzenberg, Markus

    2011-01-01

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

  3. Magnetic Fluxtube Tunneling

    Science.gov (United States)

    Dahlburg, Russell B.; Antiochos,, Spiro K.; Norton, D.

    1996-01-01

    We present numerical simulations of the collision and subsequent interaction of two initially orthogonal, twisted, force free field magnetic fluxtubes. The simulations were carried out using a new three dimensional explicit parallelized Fourier collocation algorithm for solving the viscoresistive equations of compressible magnetohydrodynamics. It is found that, under a wide range of conditions, the fluxtubes can 'tunnel' through each other. Two key conditions must be satisfied for tunneling to occur: the magnetic field must be highly twisted with a field line pitch much greater than 1, and the magnetic Lundquist number must be somewhat large, greater than or equal to 2880. This tunneling behavior has not been seen previously in studies of either vortex tube or magnetic fluxtube interactions. An examination of magnetic field lines shows that tunneling is due to a double reconnection mechanism. Initially orthogonal field lines reconnect at two specific locations, exchange interacting sections and 'pass' through each other. The implications of these results for solar and space plasmas are discussed.

  4. A computational study on oblique shock wave-turbulent boundary layer interaction

    Science.gov (United States)

    Joy, Md. Saddam Hossain; Rahman, Saeedur; Hasan, A. B. M. Toufique; Ali, M.; Mitsutake, Y.; Matsuo, S.; Setoguchi, T.

    2016-07-01

    A numerical computation of an oblique shock wave incident on a turbulent boundary layer was performed for free stream flow of air at M∞ = 2.0 and Re1 = 10.5×106 m-1. The oblique shock wave was generated from a 8° wedge. Reynolds averaged Navier-Stokes (RANS) simulation with k-ω SST turbulence model was first utilized for two dimensional (2D) steady case. The results were compared with the experiment at the same flow conditions. Further, to capture the unsteadiness, a 2D Large Eddy Simulation (LES) with sub-grid scale model WMLES was performed which showed the unsteady effects. The frequency of the shock oscillation was computed and was found to be comparable with that of experimental measurement.

  5. Molten fuel/coolant interaction studies: some results obtained with the Windscale small shock tube rig

    International Nuclear Information System (INIS)

    Higham, E.J.; Vaughan, G.J.

    1978-02-01

    Experiments are described in which water has been brought into contact with various molten metals in a shock tube, thus simulating the fall of coolant into molten uranium dioxide in a postulated reactor accident. Impact velocities of the water on to the molten material were in the range 5 to 7 m/s. Shock-pulse pressures in the water column after impact and particle size distributions of the dispersed resolidified material that was recovered were measured. The proportion of dispersed material and the size of the shock pulse (by comparison with that expected from water hammer alone) have been used as criteria for the occurrence of a molten fuel/coolant interaction and such interactions of varying degrees of violence have been found for water/aluminium, water/bismuth, water/tin, over a range of temperatures from 350 0 C to 950 0 C, for water/boric oxide, but not for water/magnesium. (author)

  6. A Comparative Study of the Behaviour of Five Dense Glass Materials Under Shock Loading Conditions

    Science.gov (United States)

    Radford, Darren D.; Proud, William G.; Field, John E.

    2001-06-01

    Previous work at the Cavendish Laboratory on the properties of glasses under shock loading has demonstrated that the material response is highly dependent upon the composition of the glass. The shock response of glass materials with an open structure, such as borosilicate, exhibits a ramping behaviour in the longitudinal stress histories due to structural collapse. Glass materials with a “filled” microstructure, as in the case of Type-D, Extra Dense Flint (DEDF) do not exhibit a ramping behaviour and behave in a manner similar to polycrystalline ceramics [1]. The current investigation compares the behaviour of five such glasses (SF15, DEDF, LACA, SF57 and DEDF-927210) under shock loading conditions. It is observed that slight changes in material composition can have a large affect on the inelastic behaviour. Principal Hugoniot and shear strength data are presented for all of the materials for pressures ranging from 2 to 14 GPa. Evidence of the so-called failure-front [2] is presented via lateral stress histories measured using manganin stress gauges and confirmed with high-speed photography. 1. Bourne, N.K., Millett, J.C.F., and Field, J.E., “On the strength of shocked glasses” Proc. R. Soc. Lond. A 455 (1999) 1275-1282 2. Brar, N.S., “Failure Waves in Glass and Ceramics Under Shock Compression”, in "Shock Compression of Condensed Matter 1999", ed. M.D. Furnish, L.C. Chhabildas, and R.S. Hixson, American Institute of Physics, Woodbury, New York, (1999) 601-606

  7. Recent results from experimental studies on laser-plasma coupling in a shock ignition relevant regime

    Czech Academy of Sciences Publication Activity Database

    Koester, P.; Antonelli, L.; Atzeni, S.; Badziak, J.; Baffigi, F.; Batani, D.; Cecchetti, C.A.; Chodukowski, T.; Consoli, F.; Cristoforetti, G.; De Angelis, R.; Folpini, G.; Gizzi, L.A.; Kalinowska, Z.; Krouský, Eduard; Kuchařík, M.; Labate, L.; Levato, T.; Liška, R.; Malka, G.; Maheut, Y.; Marocchino, A.; Nicolai, P.; O´Dell, T.; Parys, P.; Pisarczyk, T.; Rączka, P.; Renner, Oldřich; Rhee, Y.-J.; Ribeyre, X.; Richetta, M.; Rosinski, M.; Ryc, L.; Skála, Jiří; Schiavi, A.; Schurtz, G.; Šmíd, Michal; Spindloe, C.; Ullschmied, Jiří; Wolowski, J.; Zaras, A.

    2013-01-01

    Roč. 55, č. 12 (2013), , "124045-1"-"124045-8" ISSN 0741-3335 R&D Projects: GA MŠk(CZ) LC528; GA MŠk LM2010014 EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Institutional support: RVO:68378271 ; RVO:61389021 Keywords : laser-produced plasma s * inertial confinement fusion * shock ignition * X-ray imaging spectroscopy * ion diagnostics * interferometry * shock breakout chron Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.386, year: 2013

  8. Road vehicle emissions of molecular hydrogen (H 2) from a tunnel study

    Science.gov (United States)

    Vollmer, Martin K.; Juergens, Niklas; Steinbacher, Martin; Reimann, Stefan; Weilenmann, Martin; Buchmann, Brigitte

    Motor vehicle combustion emissions of molecular hydrogen (H 2), carbon monoxide (CO), and carbon dioxide (CO 2) were measured during a 6-week period from November 2004 to January 2005 in Gubrist Tunnel, Switzerland, to determine vehicle emission factors for these trace gases and the ratios of the concentration growths ΔH2/ΔCO and ΔH2/ΔCO2 in the tunnel under real-world highway driving conditions. For H 2, molar mixing ratios at the tunnel exit were found to be 7-10 ppm (parts-per-million, 10-6) during rush hours. Mean emission factors of E=49.7(±16.5)mgkm-1, ECO=1.46(±0.54)gkm-1, and E=266(±69)gkm-1 were calculated. E was largest during weekday rush-hour traffic, a consequence of the more frequent accelerations in congested traffic when fuel combustion is not optimal. E was smaller for heavy-duty vehicles (HDV) compared to light-duty vehicles (LDV), a finding which was attributed to the diesel vs. gasoline engine technology. The mean ΔH2/ΔCO molecular ratio was 0.48±0.12. This ratio increased to ˜0.6 during rush hours, suggesting that H 2 yield is favored relative to CO under fuel-rich conditions, presumably a consequence of an increasing contribution of the water-gas-shift reaction. The mean ΔH2/ΔCO2 molecular ratio was 4.4×10-3 but reduced to 2.5×10-3 when the relative HDV abundance was at maximum. Using three different approaches, road traffic H 2 emissions were estimated for 2004 for Switzerland at 5.0-6.6 Gg and globally at 4.2-8.1 Tg. Despite projections of increasing traffic, Swiss H 2 emissions are not expected to change significantly in the near future, and global emissions are likely to decrease due to improved exhaust gas clean-up technologies.

  9. Safety Evaluation of the Lighting at the Entrance of a Very Long Road Tunnel: A Case Study in Ilam

    Directory of Open Access Journals (Sweden)

    Ahmad Mehri

    2017-06-01

    Conclusion: A comparison between the results of the safe levels of lighting at the entrance of the tunnel and the De Boer scale showed that the phenomenon of black holes is created at the tunnel entrance. This may lead to a misadaptation of the drivers’ eyes to the change in luminance level at the entrance of the tunnel, thereby increasing the risk of road accidents in this zone.

  10. Tunnelling instability via perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Graffi, S. (Bologna Univ. (Italy). Dip. di Matematica); Grecchi, V. (Moderna Univ. (Italy). Dip. di Matematica); Jona-Lasinio, G. (Paris-11 Univ., 91 - Orsay (France). Lab. de Physique Theorique et Hautes Energies)

    1984-10-21

    The semiclassical limit of low lying states in a multiwell potential is studied by rigorous perturbative techniques. In particular tunnelling instability and localisation of wave functions is obtained in a simple way under small deformations of symmetric potentials.

  11. Electron tunneling studies of ultrathin films near the superconductor-to-insulator transition

    International Nuclear Information System (INIS)

    Valles, J.M. Jr.; Garno, J.P.

    1994-01-01

    Electron tunneling measurements on ultrathin quench-condensed films near the superconductor-to-insulator (SI) transition reveal that the superconducting state degrades with increasing normal state sheet resistance, R □ , in a manner that depends strongly on film morphology. In homogeneously disordered films, the superconducting energy gap Δ 0 decreases continuously and appears to go to zero at the SI transition. In granular films the transport properties degrade while Δ 0 remains constant. Measurements in the normal state reveal disorder enhanced e - -e - interaction corrections to the density of states. These effects are strong and depend on morphology in a manner that is consistent with their playing an important role in driving the SI transition. (orig.)

  12. A wind tunnel study of flows over idealised urban surfaces with roughness sublayer corrections

    Science.gov (United States)

    Ho, Yat-Kiu; Liu, Chun-Ho

    2017-10-01

    Dynamics in the roughness (RSLs) and inertial (ISLs) sublayers in the turbulent boundary layers (TBLs) over idealised urban surfaces are investigated analytically and experimentally. In this paper, we derive an analytical solution to the mean velocity profile, which is a continuous function applicable to both RSL and ISL, over rough surfaces in isothermal conditions. Afterwards, a modified mixing-length model for RSL/ISL transport is developed that elucidates how surface roughness affects the turbulence motions. A series of wind tunnel experiments are conducted to measure the vertical profiles of mean and fluctuating velocities, together with momentum flux over various configurations of surface-mounted ribs in cross flows using hot-wire anemometry (HWA). The analytical solution agrees well with the wind tunnel result that improves the estimate to mean velocity profile over urban surfaces and TBL dynamics as well. The thicknesses of RSL and ISL are calculated by monitoring the convergence/divergence between the temporally averaged and spatio-temporally averaged profiles of momentum flux. It is found that the height of RSL/ISL interface is a function of surface roughness. Examining the direct, physical influence of roughness elements on near-surface RSL flows reveals that the TBL flows over rough surfaces exhibit turbulence motions of two different length scales which are functions of the RSL and ISL structure. Conclusively, given a TBL, the rougher the surface, the higher is the RSL intruding upward that would thinner the ISL up to 50 %. Therefore, the conventional ISL log-law approximation to TBL flows over urban surfaces should be applied with caution.

  13. Glovebox-contained forty-millimeter gun system for the study of one-dimensional shock waves in toxic materials

    International Nuclear Information System (INIS)

    Honodel, C.A.

    1975-01-01

    A new gun system is being constructed at the Lawrence Livermore Laboratory for studies of the behavior of toxic materials under shock-loaded conditions. Due to the extreme toxicity of some materials, such as plutonium, the entire gun system must be enclosed in gloveboxes. Some of the experimental requirements that affected the design of the system, various diagnostic techniques that will be employed with the system, and some details of the final design that is presently under assembly are presented

  14. PROSPECTIVE STUDY TO COMPARE THE EFFICACY OF ANALGESIC AGENTS USED FOR THE PAIN MANAGEMENT DURING EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY

    OpenAIRE

    Abhirudra; Mehul; Sharada Kumar; Vilas; Vikram; Deepak; Sunil; Naveen

    2016-01-01

    BACKGROUND Extracorporeal shock wave lithotripsy (ESWL) is well known for its non-invasiveness, effectiveness and minimal morbidity for the management of renal stones. Some generation of lithotripters were associated with significant pain, needing anaesthesia. In modern lithotripters, pain is insignificant making lithotripsy an outpatient procedure (day care). AIMS The present study is aimed to compare the clinical efficacy between four drugs. METHODS AND MATERIALS This...

  15. Experimental Study on Peak Pressure of Shock Waves in Quasi-Shallow Water

    Directory of Open Access Journals (Sweden)

    Zhenxiong Wang

    2015-01-01

    Full Text Available Based on the similarity laws of the explosion, this research develops similarity requirements of the small-scale experiments of underwater explosions and establishes a regression model for peak pressure of underwater shock waves under experimental condition. Small-scale experiments are carried out with two types of media at the bottom of the water and for different water depths. The peak pressure of underwater shock waves at different measuring points is acquired. A formula consistent with the similarity law of explosions is obtained and an analysis of the regression precision of the formula confirms its accuracy. Significance experiment indicates that the influence of distance between measuring points and charge on peak pressure of underwater shock wave is the greatest and that of water depth is the least within the range of geometric parameters. An analysis of data from experiments with different media at the bottom of the water reveals an influence on the peak pressure, as the peak pressure of a shock wave in a body of water with a bottom soft mud and rocks is about 1.33 times that of the case where the bottom material is only soft mud.

  16. Use of Z pinch radiation sources for high pressure shock wave studies

    International Nuclear Information System (INIS)

    Asay, J.R.; Konrad, C.H.; Hall, C.A.; Trott, W.M.; Chandler, G.A.; Holland, K.G.; Fleming, K.J.; Trucano, T.G.

    1998-01-01

    Recent developments in pulsed power technology demonstrate use of intense radiation sources (Z pinches) for driving planar shock waves in samples with spatial dimensions larger than possible with other radiation sources. Initial indications are that the use of Z pinch sources can be used to produce planar shock waves in samples with diameters of a few millimeters and thicknesses approaching one half millimeter. These dimensions allow increased accuracy of both shock velocity and particle velocity measurements. The Z pinch radiation source uses imploding metal plasma induced by self-magnetic fields applied to wire arrays to produce high temperature x-ray environments in vacuum hohlraum enclosures. Previous experiments have demonstrated that planar shock waves can be produced with this approach. A photograph of a wire array located inside the vacuum hohlraum is shown here. Typically, a few hundred individual wires are used to produce the Z pinch source. For the shock wave experiments being designed, arrays of 120 to 240 tungsten wires with a diameter of 40 mm and with individual diameters of about 10 microm are used. Preliminary experiments have been performed on the Z pulsed radiation source to demonstrate the ability to obtain VISAR measurements in the Z accelerator environment. Analysis of these results indicate that another effect, not initially anticipated, is an apparent change in refractive index that occurs in the various optical components used in the system. This effect results in an apparent shift in the frequency of reflected laser light, and causes an error in the measured particle velocity. Experiments are in progress to understand and minimize this effect

  17. Local anesthesia for extracorporeal shock wave lithotripsy: a study comparing eutetic mixture of local anesthetics cream and lidocaine infiltration

    DEFF Research Database (Denmark)

    Honnens de Lichtenberg, M; Miskowiak, J; Mogensen, P

    1992-01-01

    A study of the anesthetic efficacy of a eutetic mixture of local anesthetics (EMLA cream) versus lidocaine infiltration in extracorporeal shock wave lithotripsy (ESWL) was done. A total of 46 patients had 30 gm. of EMLA cream applied to the skin over the kidney and 45 had subcutaneous infiltration...... anesthesia with 20 ml. 1% lidocaine with epinephrine. All patients received an intravenous dose of morphine just before ESWL. The patients were comparable with regard to age, sex, weight, morphine dosage, number of shock waves given and duration of treatment. Median pain score and the amount of supplementary...... analgesics were not significantly different between the 2 groups. There were no significant differences between the groups with regard to post-ESWL skin changes. Therefore, EMLA cream can be recommended for ESWL provided it is applied correctly....

  18. The papillary muscles as shock absorbers of the mitral valve complex. An experimental study.

    Science.gov (United States)

    Joudinaud, Thomas M; Kegel, Corrine L; Flecher, Erwan M; Weber, Patricia A; Lansac, Emmanuel; Hvass, Ulrich; Duran, Carlos M G

    2007-07-01

    Although it is known that the papillary muscles ensure the continuity between the left ventricle (LV) and the mitral apparatus, their precise mechanism needs further study. We hypothesize that the papillary muscles function as shock absorbers to maintain a constant distance between their tips and the mitral annulus during the entire cardiac cycle. Sonomicrometry crystals were implanted in five sheep in the mitral annulus at the trigones (T1 and T2), mid anterior annulus (AA) mid posterior annulus (PA), base of the posterior lateral scallops (P1 and P2), tips of papillary muscles (M1 and M2), and LV apex. LV and aortic pressures were simultaneously recorded and used to define the different phases of the cardiac cycle. No significant distance changes were found during the cardiac cycle between each papillary muscle tip and their corresponding mitral hemi-annulus: M1-T1, (3.5+/-2%); M1-P1 (5+/-2%); M1-PA (5+/-3%); M2-T2 (2.7+/-2%); M2-P2 (6.1+/-3%); and M2-AA (4.2+/-3%); (p>0.05, ANOVA). Significant changes were observed in distances between each papillary muscle tip and the contralateral hemi-mitral annulus: M1-T2 (1.7+/-3%); M1-P2 (23+/-6%); M1-AA (6+/-3%); M2-T1 (8+/-3%); M2-P1 (10.5+/-6%); and M2-PA (12.6+/-8%); (pshock absorbers to maintain the basic mitral valve geometry constant during the cardiac cycle.

  19. Comparative Shock-Tube Study of Autoignition and Plasma-Assisted Ignition of C2-Hydrocarbons

    Science.gov (United States)

    Kosarev, Ilya; Kindysheva, Svetlana; Plastinin, Eugeny; Aleksandrov, Nikolay; Starikovskiy, Andrey

    2015-09-01

    The dynamics of pulsed picosecond and nanosecond discharge development in liquid water, ethanol and hexane Using a shock tube with a discharge cell, ignition delay time was measured in a lean (φ = 0.5) C2H6:O2:Ar mixture and in lean (φ = 0.5) and stoichiometric C2H4:O2:Ar mixtures with a high-voltage nanosecond discharge and without it. The measured results were compared with the measurements made previously with the same setup for C2H6-, C2H5OH- and C2H2-containing mixtures. It was shown that the effect of plasma on ignition is almost the same for C2H6, C2H4 and C2H5OH. The reduction in time is smaller for C2H2, the fuel that is well ignited even without the discharge. Autoignition delay time was independent of the stoichiometric ratio for C2H6 and C2H4, whereas this time in stoichiometric C2H2- and C2H5OH-containing mixtures was noticeably shorter than that in the lean mixtures. Ignition after the discharge was not affected by a change in the stoichiometric ratio for C2H2 and C2H4, whereas the plasma-assisted ignition delay time for C2H6 and C2H5OH decreased as the equivalence ratio changed from 1 to 0.5. Ignition delay time was calculated in C2-hydrocarbon-containing mixtures under study by simulating separately discharge and ignition processes. Good agreement was obtained between new measurements and calculated ignition delay times.

  20. Buoyancy effects in overcooling transients calculated for the NRC pressurized thermal shock study

    International Nuclear Information System (INIS)

    Theofanous, T.G.; Iyer, K.; Nourbakhsh, H.P.; Gherson, P.

    1986-05-01

    The thermal-hydraulic responses of three PWRs (Oconee, Calvert Cliffs, and H.B. Robinson), to postulated Pressurized Thermal Shock (PTS) scenarios, which were originally determined by RELAP5 and TRAC calculations, are being further developed here with regard to buoyancy/stratification effects. These three PWRs were the subject of the NRC PTS study, and the present results helped define the thermal-hydraulic conditions utilized in the fracture mechanics calculations carried out at ORNL. The computer program REMIX, which is based on the Regional Mixing Model (RMM), was the analytical tool employed, while Purdue's 1/2-Scale HPI Thermal Mixing facility provided the basis for experimental support. Important mixing and wall heat transfer regimes are delineated on the basis of these results. We conclude that stratification is important only in cases of complete loop stagnation and that mixed-convection effects are important for downcomer flow velocities below approx.0.25 m/s. The stratification is small in magnitude, however it is important in creating a recirculating flow pattern which activates the lower plenum, pump and loop seal volumes, to participate in the mixing process. This mixing process together with the heat input from the wall metal significantly impact the cooldown rates. Heat transfer in the plume region is dominated by forced convection. On the other hand, the presence of the Reactor Pressure Vessel (RPV) wall cladding and wall conduction significantly dampen the free convection effects in the low velocity, mixed-convection, regime. For the stagnant loop cases, all locations outside the plume region are included in this regime. In the presence of natural loop circulation and a uniformly distributed downcomer flow, the mixed convection regime is also expected, however, the forced convection regime can also be observed in highly asymmetric flow behavior