WorldWideScience

Sample records for research tunnel irt

  1. Icing Research Tunnel

    Science.gov (United States)

    Chennault, Jonathan

    2004-01-01

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

  2. Strategy for Sustainable Utilization of IRT-Sofia Research Reactor

    International Nuclear Information System (INIS)

    Mitev, M.; Apostolov, T.; Ilieva, K.; Belousov, S.; Nonova, T.

    2013-01-01

    The Research Reactor IRT-2000 in Sofia is in process of reconstruction into a low-power reactor of 200 kW under the decision of the Council of Ministers of Republic of Bulgaria from 2001. The reactor will be utilized for development and preservation of nuclear science, skills, and knowledge; implementation of applied methods and research; education of students and training of graduated physicists and engineers in the field of nuclear science and nuclear energy; development of radiation therapy facility. Nuclear energy has a strategic place within the structure of the country’s energy system. In that aspect, the research reactor as a material base, and its scientific and technical personnel, represent a solid basis for the development of nuclear energy in our country. The acquired scientific experience and qualification in reactor operation are a precondition for the equal in rights participation of the country in the international cooperation and the approaching to the European structures, and assurance of the national interests. Therefore, the operation and use of the research reactor brings significant economic benefits for the country. For education of students in nuclear energy, reactor physics experiments for measurements of static and kinetic reactor parameters will be carried out on the research reactor. The research reactor as a national base will support training and applied research, keep up the good practice and the preparation of specialists who are able to monitor radioactivity sources, to develop new methods for detection of low quantities of radioactive isotopes which are hard to find, for deactivation and personal protection. The reactor will be used for production of isotopes needed for medical therapy and diagnostics; it will be the neutron source in element activation analysis having a number of applications in industrial production, medicine, chemistry, criminology, etc. The reactor operation will increase the public understanding, confidence

  3. Preliminary Analysis on the Management Options of IRT-DPRK Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jung-Hyun; Kim, Minsoo; Hwang, Yongsoo [Korea Institute of Nuclear Nonproliferation and Control, Daejeon (Korea, Republic of)

    2015-05-15

    Although IRT-DPRK was upgraded several times, operation lifetime was already exhausted and thus management policy is needed to deal with the aging of IRT-DPRK. For example, IRT- 2000 type nuclear reactors in Georgia and Bulgaria had been shut down to refurbish or decommissioned to establish new low power facilities. However, the existing negotiations and agreements related to the nuclear issues on North Korea have been focused on the 'denuclearization', and thus the issues on the IRTDPRK were not handled. In recent, a group of USA scientists has suggested that IRT-DPRK should be refurbished to establish the 'Scientific cent for excellence' like the Cooperative Threat Reduction program applied in Russia and the former Soviet Union (FSU). In this paper, we examined the several options to manage the IRT-DPRK through the study of similar foreign cases. Due to the lack of the detailed and standardized information, it is impossible to suggest the best option at this moment. In order to do that, the further research on the detailed procedures, radioactive wastes, the standards of safety and security are needed.

  4. Finite Mixture Multilevel Multidimensional Ordinal IRT Models for Large Scale Cross-Cultural Research

    Science.gov (United States)

    de Jong, Martijn G.; Steenkamp, Jan-Benedict E. M.

    2010-01-01

    We present a class of finite mixture multilevel multidimensional ordinal IRT models for large scale cross-cultural research. Our model is proposed for confirmatory research settings. Our prior for item parameters is a mixture distribution to accommodate situations where different groups of countries have different measurement operations, while…

  5. General plan for the partial dismantling of the IRT-Sofia research reactor

    Directory of Open Access Journals (Sweden)

    Apostolov Tihomir G.

    2006-01-01

    Full Text Available After the decision of the Bulgarian Government to reconstruct it, the strategy concerning the IRT-Sofia Research Reactor is to partially dismantle the old systems and equipment. The removal of the reactor core and replacement of old equipment will not pose any significant problems. For a more efficient use of existing resources, there is a need for an engineering project which has been already prepared under the title "General Plan for the Partial Dismantling of Equipment at the IRT-Sofia as a Part of the Reconstruction into a Low Power RR".

  6. The development of the nuclear physics in Latvia II. The building of the Research Nuclear Reactor IRT

    International Nuclear Information System (INIS)

    Ulmanis, U.

    2004-01-01

    Nuclear research reactor IRT of the Academy of Sciences was built near Riga in Salaspils. IRT is pool aqueous - aqueous reactor with nuclear fuel U-235 contained elements, located in the core at a depth of ∼ 7 m under distilled water. Ten horizontal and 10-15 vertical experimental channels are employed in experimental research with the use of neutron fluxes. For the research with gamma rays is constructed radiation loop facility with liquid In-Ga-SN solid solution as intensive gamma-ray sources. Main activities of IRT are to conduct research in nuclear spectroscopy, neutron activation analysis, neutron diffraction and radiation physics, chemistry and biology. (authors)

  7. Future development of the research nuclear reactor IRT-2000 in Sofia

    International Nuclear Information System (INIS)

    Apostolov, T.G.

    1999-01-01

    The present paper presents a short description of the research reactor IRT-2000 Sofia, started in 1961 and operated for 28 years. Some items are considered, connected to the improvements made in the contemporary safety requirements and the unrealized project for modernization to 5 MW. Proposals are considered for reconstruction of reactor site to a 'reactor of low power' for education purposes and as a basis for the country's nuclear technology development. (author)

  8. Future development of the research nuclear reactor IRT-2000 in Sofia

    Energy Technology Data Exchange (ETDEWEB)

    Apostolov, T.G. [Institute for Nuclear Research and Nuclear Energy, BAS, Sofia (Bulgaria)

    1999-07-01

    The present paper presents a short description of the research reactor IRT-2000 Sofia, started in 1961 and operated for 28 years. Some items are considered, connected to the improvements made in the contemporary safety requirements and the unrealized project for modernization to 5 MW. Proposals are considered for reconstruction of reactor site to a 'reactor of low power' for education purposes and as a basis for the country's nuclear technology development. (author)

  9. Licensing activities for the partial decommissioning of IRT-2000 research reactor in Sofia

    International Nuclear Information System (INIS)

    Apostolov, T.; Ilieva, Kr.; Papukchiev, A.; Kalchev, B.

    2001-01-01

    The project for refurbishment of IRT-2000 research reactor in Sofia into low-power reactor (200 kW) is based on the retention of some IRT-2000 buildings, facilities and equipment. The activities, which determine the partial decommissioning should be realized in accordance with preliminary developed licensing documents as General Plan, Safety Analysis Report and Environment Impact assessment Report. The goal of these documents is to provide and guarantee safe and effective activities with radioactive materials, to define strictly the dismantling procedures, and in the same time to minimize their influence on the environment. The Technical Tasks for General Plan, Safety Analysis Report and Environment Impact Assessment Report have been prepared and will be presented as preliminary licensing documents to the National Regulatory Body for approval before their application. A Quality Management system is being developed nowadays at INRNE. After its certification some requirements of the regulatory body will be completed. This certified QA system is a major part of the licensing procedure for the reconstruction of IRT-2000 research reactor. (author)

  10. Flow Quality Surveys in the Settling Chamber of the NASA Glenn Icing Research Tunnel (2011 Tests)

    Science.gov (United States)

    Steen, Laura E.; VanZante, Judith Foss; Broeren, Andy P.; Kubiak, Mark J.

    2014-01-01

    In 2011, the heat exchanger and refrigeration plant for NASA Glenn Research Centers Icing Research Tunnel (IRT) were upgraded. Flow quality surveys were performed in the settling chamber of the IRT in order to understand the effect that the new heat exchanger had on the flow quality upstream of the spray bars. Measurements were made of the total pressure, static pressure, total temperature, airspeed, and flow angle (pitch and yaw). These measurements were directly compared to measurements taken in 2000, after the previous heat exchanger was installed. In general, the flow quality appears to have improved with the new heat exchanger.

  11. KAERI underground research tunnel (KURT)

    International Nuclear Information System (INIS)

    Cho, Won Jin; Kwon, Sang Ki; Park, Jeong Hwa; Choi, Jong Won

    2007-01-01

    An underground research tunnel is essential to validate the integrity of a high-level waste disposal system, and the safety of geological disposal. In this study, KAERI underground research tunnel (KURT) was constructed in the site of Korea Atomic Energy Research Institute(KAERI). The results of the site investigation and the design of underground tunnel were presented. The procedure for the construction permits and the construction of KURT were described briefly. The in-situ experiments being carried out at KURT were also introduced

  12. Measurement of isothermal temperature reactivity coefficient at research reactor with IRT-4M fuel

    International Nuclear Information System (INIS)

    Bily, Tomas; Sklenka, Lubomir

    2014-01-01

    Highlights: • Isothermal coefficient of reactivity with IRT-4M fuel was measured. • Experiment was performed at VR-1 zero power reactor. • Tailor-made instrumentation was used. • MCNP code was used for analysis of experimental data. - Abstract: Transients analyses is of high importance for reactor safety studies. The temperature reactivity coefficients belong to key input parameters for such studies. However, the amount of experimental data for validation of such parameters for the conditions of research reactors operated with LEU fuel is limited. To improve the situation, a tailor-made experimental instrumentation has been recently developed at zero power research reactor VR-1 that allows for detailed measurement of temperature reactivity effects in lattices with IRT-4M fuel. The instrumentation enables by external water heater to change the temperature of fuel and surrounding water moderator in 2 × 2 positions of reactor grid in the range from 20 to 40 °C. Using the instrumentation the isothermal temperature reactivity effect was measured for a group of four eight-tube fuel assemblies in the above mentioned temperature range. Results were compared to MCNP calculations with the precise model of the VR-1 reactor. The MCNP code was further used for deeper analysis of experimental data

  13. "We Freeze to Please": A History of NASA's Icing Research Tunnel and the Quest for Flight Safety

    Science.gov (United States)

    Leary, William M.

    2002-01-01

    The formation of ice on wings and other control surfaces of airplanes is one of the oldest and most vexing problems that aircraft engineers and scientists continue to face. While no easy, comprehensive answers exist, the staff at NASAs Icing Research Tunnel (IRT) at the Glenn Research Center in Cleveland has done pioneering work to make flight safer for experimental, commercial, and military customers. The National Advisory Committee for Aeronautics (NACA) initiated government research on aircraft icing in the 1930s at its Langley facility in Virginia. Icing research shifted to the NACA's Cleveland facility in the 1940s. Initially there was little focus on icing at either location, as these facilities were more concerned with aerodynamics and engine development. With several high-profile fatal crashes of air mail carriers, however, the NACA soon realized the need for a leading research facility devoted to icing prevention and removal. The IRT began operation in 1944 and, despite renovations and periodic attempts to shut it down, has continued to function productively for almost 60 years. In part because icing has proved so problematic over time, IRT researchers have been unusually open-minded in experimenting with a wide variety of substances, devices, and techniques. Early icing prevention experiments involved grease, pumping hot engine exhaust onto the wings, glycerin soap, mechanical and inflatable "boots," and even corn syrup. The IRT staff also looked abroad for ideas and later tried a German and Soviet technique of electromagnetism, to no avail. More recently, European polymer fluids have been more promising. The IRT even periodically had "amateur nights" in which a dentist's coating for children's teeth proved unequal to the demands of super-cooled water droplets blown at 100 miles per hour. Despite many research dead-ends, IRT researchers have achieved great success over the years. They have developed important computer models, such as the LEWICE software

  14. A study for the KAERI research tunnel

    International Nuclear Information System (INIS)

    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

  15. A Two-Phase Emission Liquid Xe Detector for Study of Low-Ionization Events at the Research Reactor IRT MEPhI

    Science.gov (United States)

    Akimov, D. Yu.; Alexandrov, I. S.; Belov, V. A.; Bolozdynya, A. I.; Burenkov, A. A.; Chepurnov, A. S.; Danilov, M. V.; Efremenko, Yu. V.; Etenko, A. V.; Gromov, M. B.; Gulin, M. A.; Ivakhin, S. V.; Kaplin, V. A.; Karelin, A. K.; Khromov, A. V.; Kirsanov, M. A.; Klimanov, S. G.; Kobyakin, A. S.; Konovalov, A. M.; Kovalenko, A. G.; Krakhmalova, T. D.; Kuchenkov, A. V.; Kumpan, A. V.; Lukyanchenko, G. A.; Melikyan, Yu. A.; Nikolaev, R. I.; Nurakhov, N. N.; Rudik, D. G.; Saldikov, I. S.; Skorokhvatov, M. D.; Sosnovtsev, V. V.; Stekhanov, V. N.; Tikhomirov, G. V.

    2015-02-01

    A two-phase emission detector containing 5 kg of liquid Xe is installed at the horizontal experimental channel of the research nuclear reactor IRT MEPhI to measure the liquid Xe response to nuclei recoils with kinetic energies below 1 keV. Preliminary tests have demonstrated that ≥ 15 μs electron lifetime in liquid Xe and 10 photoelectrons single ionization electron signal are achieved. These parameters are sufficient to detect and identify events at the single electron level.

  16. An IRT Scale Transformation Method for Parameters Calibrated from Multiple Samples of Subjects. ACT Research Report Series 96-2.

    Science.gov (United States)

    Zeng, Lingjia

    A problem frequently confronted in item response theory (IRT) applications is that the item parameters calibrated using more than two independent samples of subjects must be expressed on the same scale. The existing methods were developed for a pairwise transformation, that is, from one scale to the other. The purpose of this study is to introduce…

  17. Results and Conclusions from the NASA Isokinetic Total Water Content Probe 2009 IRT Test

    Science.gov (United States)

    Reehorst, Andrew; Brinker, David

    2010-01-01

    The NASA Glenn Research Center has developed and tested a Total Water Content Isokinetic Sampling Probe. Since, by its nature, it is not sensitive to cloud water particle phase nor size, it is particularly attractive to support super-cooled large droplet and high ice water content aircraft icing studies. The instrument comprises the Sampling Probe, Sample Flow Control, and Water Vapor Measurement subsystems. Results and conclusions are presented from probe tests in the NASA Glenn Icing Research Tunnel (IRT) during January and February 2009. The use of reference probe heat and the control of air pressure in the water vapor measurement subsystem are discussed. Several run-time error sources were found to produce identifiable signatures that are presented and discussed. Some of the differences between measured Isokinetic Total Water Content Probe and IRT calibration seems to be caused by tunnel humidification and moisture/ice crystal blow around. Droplet size, airspeed, and liquid water content effects also appear to be present in the IRT calibration. Based upon test results, the authors provide recommendations for future Isokinetic Total Water Content Probe development.

  18. Effect of Item Response Theory (IRT) Model Selection on Testlet-Based Test Equating. Research Report. ETS RR-14-19

    Science.gov (United States)

    Cao, Yi; Lu, Ru; Tao, Wei

    2014-01-01

    The local item independence assumption underlying traditional item response theory (IRT) models is often not met for tests composed of testlets. There are 3 major approaches to addressing this issue: (a) ignore the violation and use a dichotomous IRT model (e.g., the 2-parameter logistic [2PL] model), (b) combine the interdependent items to form a…

  19. Design Recommendations for Concrete Tunnel Linings : Volume II. Summary of Research and Proposed Recommendations.

    Science.gov (United States)

    1983-11-01

    The report presents design recommendations for concrete tunnel linings for transportation tunnels. The recommendations developed as a result of in-depth analysis and model testing of the behavior of concrete tunnel linings. The research addressed pro...

  20. The development of the nuclear physics in Latvia III. The research nuclear reactor IRT begins to work in Latvia

    International Nuclear Information System (INIS)

    Ulmanis, U.

    2005-01-01

    This article is associated with the study of reactors technical parameters with specific interest on the effect the distribution of neutron and gamma radiation through the reactor's cooling systems has on the environment. Scientist began by implementing monitoring system to assist in the research of nuclear spectroscopy, neutron activation analysis, neutron diffraction, solid-state radiation physics, chemistry and radiobiology. The first sets of results are summarized with in the article. (author)

  1. IRT-based test construction

    NARCIS (Netherlands)

    van der Linden, Willem J.; Theunissen, T.J.J.M.; Boekkooi-Timminga, Ellen; Kelderman, Henk

    1987-01-01

    Four discussions of test construction based on item response theory (IRT) are presented. The first discussion, "Test Design as Model Building in Mathematical Programming" (T.J.J.M. Theunissen), presents test design as a decision process under certainty. A natural way of modeling this process leads

  2. Materials and construction techniques for cryogenic wind tunnel facilities for instruction/research use

    Science.gov (United States)

    Morse, S. F.; Roper, A. T.

    1975-01-01

    The results of the cryogenic wind tunnel program conducted at NASA Langley Research Center are presented to provide a starting point for the design of an instructional/research wind tunnel facility. The advantages of the cryogenic concept are discussed, and operating envelopes for a representative facility are presented to indicate the range and mode of operation. Special attention is given to the design, construction and materials problems peculiar to cryogenic wind tunnels. The control system for operation of a cryogenic tunnel is considered, and a portion of a linearized mathematical model is developed for determining the tunnel dynamic characteristics.

  3. Measuring individual significant change on the Beck Depression Inventory-II through IRT-based statistics.

    NARCIS (Netherlands)

    Brouwer, D.; Meijer, R.R.; Zevalkink, D.J.

    2013-01-01

    Several researchers have emphasized that item response theory (IRT)-based methods should be preferred over classical approaches in measuring change for individual patients. In the present study we discuss and evaluate the use of IRT-based statistics to measure statistical significant individual

  4. Measuring individual significant change on the Beck Depression Inventory-II through IRT-based statistics

    NARCIS (Netherlands)

    Brouwer, Danny; Meijer, Rob; Zevalkink, J.

    2013-01-01

    Several researchers have emphasized that item response theory (IRT)-based methods should be preferred over classical approaches in measuring change for individual patients. In the present study we discuss and evaluate the use of IRT-based statistics to measure statistical significant individual

  5. Comparison of Differential Item Functioning Determination Techniques: HGLM, LR and IRT-LR

    Science.gov (United States)

    Acar, Tulin; Kelecioglu, Hulya

    2010-01-01

    The aim of this research is to determine differential item functioning (DIF) by hierarchical linear modeling (HGLM) on test items and comparing these results by the DIF results determined by logistic regression (LR) and IRT-likelihood ratio (IRT-LR) techniques. Investigating the concordance between the techniques in determining the items with DIF,…

  6. Estimating a Noncompensatory IRT Model Using Metropolis within Gibbs Sampling

    Science.gov (United States)

    Babcock, Ben

    2011-01-01

    Relatively little research has been conducted with the noncompensatory class of multidimensional item response theory (MIRT) models. A Monte Carlo simulation study was conducted exploring the estimation of a two-parameter noncompensatory item response theory (IRT) model. The estimation method used was a Metropolis-Hastings within Gibbs algorithm…

  7. Research on he Classification of Life-Cycle Safety Monitoring Levels of Subsea Tunnels

    Directory of Open Access Journals (Sweden)

    Lu Junfu

    2017-08-01

    Full Text Available As a traffic engineering project across straits or gulfs, subsea tunnel is one of the oceaneering with great construction difficulties, and the key to the success of subsea tunnel engineering lies in timely and accurate assessment of the structure safety of subsea tunnel engineering construction and life-cycle. Xiang’an Xiamen subsea tunnel is China’s first subsea tunnel which crosses complex formation conditions, engineering accidents such as collapse, sudden inflow of water or mud might occur during tunnel construction and operation. Therefore, the concept of subsea tunnel life-cycle monitoring is proposed aiming at the particularity of subsea tunnels. The variation forms of subsea tunnel mainly include large deformation, collapse, primary support cracking, water leakage, water pressure increase, steel arch corrosion, concrete corrosion, longitudinal differential settlement, etc., and classification of the life-cycle safety monitoring levels of the subsea tunnel is conducted based on risk assessment theory and risk level management benchmark to determine the possible variation forms in the monitoring level segments. The research results will provide reference for the subsea tunnel life-cycle monitoring, disaster warning as well as risk management under construction or to be built at home and abroad.

  8. Wind-Tunnel Balance Characterization for Hypersonic Research Applications

    Science.gov (United States)

    Lynn, Keith C.; Commo, Sean A.; Parker, Peter A.

    2012-01-01

    Wind-tunnel research was recently conducted at the NASA Langley Research Center s 31-Inch Mach 10 Hypersonic Facility in support of the Mars Science Laboratory s aerodynamic program. Researchers were interested in understanding the interaction between the freestream flow and the reaction control system onboard the entry vehicle. A five-component balance, designed for hypersonic testing with pressurized flow-through capability, was used. In addition to the aerodynamic forces, the balance was exposed to both thermal gradients and varying internal cavity pressures. Historically, the effect of these environmental conditions on the response of the balance have not been fully characterized due to the limitations in the calibration facilities. Through statistical design of experiments, thermal and pressure effects were strategically and efficiently integrated into the calibration of the balance. As a result of this new approach, researchers were able to use the balance continuously throughout the wide range of temperatures and pressures and obtain real-time results. Although this work focused on a specific application, the methodology shown can be applied more generally to any force measurement system calibration.

  9. Research on distributed temperature sensor (DTS) applied in underground tunnel

    Science.gov (United States)

    Hu, Chuanlong; Wang, Jianfeng; Zhang, Zaixuan; Shen, Changyu; Jin, Yongxing; Jin, Shangzhong

    2011-11-01

    A distributed temperature sensor (DTS) system with a sensing distance of 4 km was developed for applications in tunnel temperature measurement and fire alarm. Characteristics of DTS and experiment results are introduced. The results show that DTS system can play an important role in tunnel fire alarm.

  10. Mokken scale analysis of mental health and well-being questionnaire item responses: a non-parametric IRT method in empirical research for applied health researchers

    Directory of Open Access Journals (Sweden)

    Stochl Jan

    2012-06-01

    Full Text Available Abstract Background Mokken scaling techniques are a useful tool for researchers who wish to construct unidimensional tests or use questionnaires that comprise multiple binary or polytomous items. The stochastic cumulative scaling model offered by this approach is ideally suited when the intention is to score an underlying latent trait by simple addition of the item response values. In our experience, the Mokken model appears to be less well-known than for example the (related Rasch model, but is seeing increasing use in contemporary clinical research and public health. Mokken's method is a generalisation of Guttman scaling that can assist in the determination of the dimensionality of tests or scales, and enables consideration of reliability, without reliance on Cronbach's alpha. This paper provides a practical guide to the application and interpretation of this non-parametric item response theory method in empirical research with health and well-being questionnaires. Methods Scalability of data from 1 a cross-sectional health survey (the Scottish Health Education Population Survey and 2 a general population birth cohort study (the National Child Development Study illustrate the method and modeling steps for dichotomous and polytomous items respectively. The questionnaire data analyzed comprise responses to the 12 item General Health Questionnaire, under the binary recoding recommended for screening applications, and the ordinal/polytomous responses to the Warwick-Edinburgh Mental Well-being Scale. Results and conclusions After an initial analysis example in which we select items by phrasing (six positive versus six negatively worded items we show that all items from the 12-item General Health Questionnaire (GHQ-12 – when binary scored – were scalable according to the double monotonicity model, in two short scales comprising six items each (Bech’s “well-being” and “distress” clinical scales. An illustration of ordinal item analysis

  11. Mokken scale analysis of mental health and well-being questionnaire item responses: a non-parametric IRT method in empirical research for applied health researchers.

    Science.gov (United States)

    Stochl, Jan; Jones, Peter B; Croudace, Tim J

    2012-06-11

    Mokken scaling techniques are a useful tool for researchers who wish to construct unidimensional tests or use questionnaires that comprise multiple binary or polytomous items. The stochastic cumulative scaling model offered by this approach is ideally suited when the intention is to score an underlying latent trait by simple addition of the item response values. In our experience, the Mokken model appears to be less well-known than for example the (related) Rasch model, but is seeing increasing use in contemporary clinical research and public health. Mokken's method is a generalisation of Guttman scaling that can assist in the determination of the dimensionality of tests or scales, and enables consideration of reliability, without reliance on Cronbach's alpha. This paper provides a practical guide to the application and interpretation of this non-parametric item response theory method in empirical research with health and well-being questionnaires. Scalability of data from 1) a cross-sectional health survey (the Scottish Health Education Population Survey) and 2) a general population birth cohort study (the National Child Development Study) illustrate the method and modeling steps for dichotomous and polytomous items respectively. The questionnaire data analyzed comprise responses to the 12 item General Health Questionnaire, under the binary recoding recommended for screening applications, and the ordinal/polytomous responses to the Warwick-Edinburgh Mental Well-being Scale. After an initial analysis example in which we select items by phrasing (six positive versus six negatively worded items) we show that all items from the 12-item General Health Questionnaire (GHQ-12)--when binary scored--were scalable according to the double monotonicity model, in two short scales comprising six items each (Bech's "well-being" and "distress" clinical scales). An illustration of ordinal item analysis confirmed that all 14 positively worded items of the Warwick-Edinburgh Mental

  12. Enabling Advanced Wind-Tunnel Research Methods Using the NASA Langley 12-Foot Low Speed Tunnel

    Science.gov (United States)

    Busan, Ronald C.; Rothhaar, Paul M.; Croom, Mark A.; Murphy, Patrick C.; Grafton, Sue B.; O-Neal, Anthony W.

    2014-01-01

    Design of Experiment (DOE) testing methods were used to gather wind tunnel data characterizing the aerodynamic and propulsion forces and moments acting on a complex vehicle configuration with 10 motor-driven propellers, 9 control surfaces, a tilt wing, and a tilt tail. This paper describes the potential benefits and practical implications of using DOE methods for wind tunnel testing - with an emphasis on describing how it can affect model hardware, facility hardware, and software for control and data acquisition. With up to 23 independent variables (19 model and 2 tunnel) for some vehicle configurations, this recent test also provides an excellent example of using DOE methods to assess critical coupling effects in a reasonable timeframe for complex vehicle configurations. Results for an exploratory test using conventional angle of attack sweeps to assess aerodynamic hysteresis is summarized, and DOE results are presented for an exploratory test used to set the data sampling time for the overall test. DOE results are also shown for one production test characterizing normal force in the Cruise mode for the vehicle.

  13. Thermal analysis of IRT-T reactor fuel elements

    OpenAIRE

    Naymushin, Artem Georgievich; Chertkov, Yuri Borisovich; Lebedev, Ivan Igorevich; Anikin, Mikhail Nikolaevich

    2015-01-01

    The article describes the method and results of thermo-physical calculations of IRT-T reactor core. Heat fluxes, temperatures of cladding, fuel meat and coolant were calculated for height of core, azimuth directions of FA and each fuel elements in FA. Average calculated values of uniformity factor of energy release distribution for height of fuel assemblies were shown in this research. Onset nucleate boiling temperature and ONB-ratio were calculated. Shows that temperature regimes of fuel ele...

  14. Wind tunnel productivity status and improvement activities at NASA Langley Research Center

    Science.gov (United States)

    Putnam, Lawrence E.

    1996-01-01

    Over the last three years, a major effort has been underway to re-engineering the way wind tunnel testing is accomplished at the NASA Langley Research Center. This effort began with the reorganization of the LaRC and the consolidation of the management of the wind tunnels in the Aerodynamics Division under one operations branch. This paper provides an overview of the re-engineering activities and gives the status of the improvements in the wind tunnel productivity and customer satisfaction that have resulted from the new ways of working.

  15. Rotary Balance Wind Tunnel Testing for the FASER Flight Research Aircraft

    Science.gov (United States)

    Denham, Casey; Owens, D. Bruce

    2016-01-01

    Flight dynamics research was conducted to collect and analyze rotary balance wind tunnel test data in order to improve the aerodynamic simulation and modeling of a low-cost small unmanned aircraft called FASER (Free-flying Aircraft for Sub-scale Experimental Research). The impetus for using FASER was to provide risk and cost reduction for flight testing of more expensive aircraft and assist in the improvement of wind tunnel and flight test techniques, and control laws. The FASER research aircraft has the benefit of allowing wind tunnel and flight tests to be conducted on the same model, improving correlation between wind tunnel, flight, and simulation data. Prior wind tunnel tests include a static force and moment test, including power effects, and a roll and yaw damping forced oscillation test. Rotary balance testing allows for the calculation of aircraft rotary derivatives and the prediction of steady-state spins. The rotary balance wind tunnel test was conducted in the NASA Langley Research Center (LaRC) 20-Foot Vertical Spin Tunnel (VST). Rotary balance testing includes runs for a set of given angular rotation rates at a range of angles of attack and sideslip angles in order to fully characterize the aircraft rotary dynamics. Tests were performed at angles of attack from 0 to 50 degrees, sideslip angles of -5 to 10 degrees, and non-dimensional spin rates from -0.5 to 0.5. The effects of pro-spin elevator and rudder deflection and pro- and anti-spin elevator, rudder, and aileron deflection were examined. The data are presented to illustrate the functional dependence of the forces and moments on angle of attack, sideslip angle, and angular rate for the rotary contributions to the forces and moments. Further investigation is necessary to fully characterize the control effectors. The data were also used with a steady state spin prediction tool that did not predict an equilibrium spin mode.

  16. The IRTS (Infrared Telescope in Space) Mission

    Science.gov (United States)

    Murakami, Hiroshi; Freund, Minoru M.; Ganga, Ken; Guo, Hongfeng; Hirao, Takanori; Hiromoto, Norihisa; Kawada, Mitsunobu; Lange, Andrew E.; Makiuti, Sin'itirou; Matsuhara, Hideo; Matsumoto, Toshio; Matsuura, Shuji; Murakami, Masahide; Nakagawa, Takao; Narita, Masanao; Noda, Manabu; Okuda, Haruyuki; Okumura, Ken'ichi; Onaka, Takashi; Roellig, Thomas L.; Sato, Shinji; Shibai, Hiroshi; Smith, Beverly J.; Tanabe, Toshihiko; Tanaka, Masahiro; Watabe, Toyoki; Yamamura, Issei; Yuen, Lunming

    1996-10-01

    The Japanese satellite-borne infrared telescope, the Infrared Telescope in Space (IRTS), has completed a successful survey of a portion of the infrared sky. The IRTS consists of a 15 cm telescope cooled with superfluid liquid helium, and is installed on board the Space Flyer Unit (SFU) spacecraft. The SFU was launched on 1995 March 18 UT. The sky survey by the IRTS started on March 29 UT, and was completed on April 25 UT after exhausting its liquid helium. The cryogenic system operated as designed, and maintained the telescope and the focal-plane instruments at a stable temperature of 1.9 K for 38 days. The four focal-plane instruments, which together covered almost the entire infrared wavelength range, observed a sky area of about 2700 deg(2) and returned a wealth of new data on a variety of objects, including the zodiacal light, interstellar gas and dust, near-infrared cosmic background light and point sources.

  17. Borehole heater test at KAERI Underground Research Tunnel

    International Nuclear Information System (INIS)

    Kwon, S. K.; Cho, W. J.; Jeon, S. W.

    2009-09-01

    At HLW repository, the temperature change due to the decay heat in near field can affect the hydraulic, mechanical, and chemical behaviors and influence on the repository safety. Therefore, the understanding of the thermal behavior in near field is essential for the site selection, design, as well as operation of the repository. In this study, various studies for the in situ heater test, which is for the investigation of the thermo-mechanical behavior in rock mass, were carried out. At first, similar in situ tests at foreign URLs were reviewed and summarized the major conclusions from the tests. After then an adequate design of heater, observation sensors, and data logging system were developed and installed with a consideration of the site condition and test purposes. In order to minimize the effect of hydraulic phenomenon, a relatively day zone was chosen for the in situ test. Joint distribution and characteristics in the zone were surveyed and the rock mass properties were determined with various laboratory tests. In this study, an adequate location for an in situ borehole heater test was chosen. Also a heater for the test was designed and manufactured and the sensors for measuring the rock behavior were installed. It was possible to observe that stiff joints are developed overwhelmingly in the test area from the joint survey at the tunnel wall. The major rock and rock mass properties at the test site could be determined from the thermo-mechanical laboratory tests using the rock cores retrieved from the site. The measured data were implemented in the three-dimensional computer simulation. From the modeling using FLAC3D code, it was possible to find that the heat convection through the tunnel wall can influence on temperature distribution in rock. Because of that it was necessary to installed a blocking wall to minimize the effect of ventilation system on the heater test, which is carrying out nearby the tunnel wall. The in situ borehole heater test is the first

  18. IRTS observation of zodiacal light and emission

    Science.gov (United States)

    Matsumoto, T.; Murakami, H.; Onaka, T.; Ootsubo, T.; Roellig, T. L.; Chan, K. -W.; Noda, M.

    1998-01-01

    We present the infrared spectrum of the zodiacal light and emission obtained by the Near-Infrared Spectrometer (NIRS) and Mid-Infrared Spectrometer (MIRS) onboard the Infrared Telescope in Space (IRTS). The wavelength coverages and spectral resolutions are 1.4-4.0 microns and 0.12 microns for the NIRS, and 4.5-11.7 microns and 0.23-0.36 microns for the MIRS respectively. Both instruments have the same beam size of 8 arcminutes square. The IRTS observations were made for 1995 March 29 - April 26. Here we present the data of two days, April 19 and April 20.

  19. The Infrared Telescope in Space (IRTS)

    Science.gov (United States)

    Murakami, H.; Bock, J.; Freund, M. M.; Guo, H.; Hirao, T.; Lange, A. E.; Matsuhara, H.; Matsumoto, T.; Matsuura, S.; McMahon, T. J.; Murakami, M.; Nakagawa, T.; Noda, M.; Noguchi, K.; Okuda, H.; Okumura, K.; Onaka, T.; Roellig, T. L.; Sato, S.; Shibai, H.; Tanabe, T.; Watabe, T.; Yagi, T.; Yajima, N.; Yui, M.

    1994-06-01

    The Infrared Telescope in Space (IRTS) is a cryogenically cooled small infrared telescope that will fly aboard the small space platform Space Flyer Unit. It will survey approximately 10% of the sky with a relatively wide beam during its 20 day emission. Four focal-plane instruments will make simultaneous observations of the sky at wavelengths ranging from 1 to 1000 microns. The IRTS will provide significant information on cosmology, interstellar matter, late-type stars, and interplanetary dust. This paper describes the instrumentation and mission.

  20. Current state of works on the neutron-activation analysis carried out at IRT-T of the Scientific Research Institute at Tomsk Polytechnic University

    International Nuclear Information System (INIS)

    Glukhov, G.G.; Kabanov, D.V.; Kryazheva, T.N.; Maslennikov, Yu.S.; Merkulov, V.G.

    2010-01-01

    The paper introduces the main directions of works in the field of neutron-activation analysis performed in the reactor of the Scientific Research Institute of Nuclear Physics at Tomsk Polytechnic University. It presents the capabilities of the neutron-activation analysis that make it the leading means in solving various analytical problems. (authors)

  1. Highly cited articles in wind tunnel-related research: a bibliometric analysis.

    Science.gov (United States)

    Mo, Ziwei; Fu, Hui-Zhen; Ho, Yuh-Shan

    2018-03-22

    Wind tunnels have been widely employed in aerodynamic research. To characterize the high impact research, a bibliometric analysis was conducted on highly cited articles related to wind tunnel based on the Science Citation Index Expanded (SCI-EXPANDED) database from 1900 to 2014. Articles with at least 100 citations from the Web of Science Core Collection were selected and analyzed in terms of publication years, authors, institutions, countries/territories, journals, Web of Science categories, and citation life cycles. The results show that a total of 77 highly cited articles in 37 journals were published between 1959 and 2008. Journal of Fluid Mechanics published the most of highly cited articles. The USA was the most productive country and most frequent partner of internationally collaboration. The prolific institutions were mainly located in the USA and UK. The authors who were both first author and corresponding author published 88% of the articles. The Y index was also deployed to evaluate the publication characteristics of authors. Moreover, the articles with high citations in both history and the latest year with their citation life cycles were examined to provide insights for high impact research. The highly cited articles were almost earliest wind tunnel experimental data and reports on their own research specialty, and thus attracted high citations. It was revealed that classic works of wind tunnel research was frequently occurred in 1990s but much less in 2000s, probably due to the development of numerical models of computational fluid dynamic (CFD) in recent decades.

  2. IRT analyses of the Swedish Dark Triad Dirty Dozen

    Directory of Open Access Journals (Sweden)

    Danilo Garcia

    2018-03-01

    Full Text Available Background: The Dark Triad (i.e., Machiavellianism, narcissism, and psychopathy can be captured quickly with 12 items using the Dark Triad Dirty Dozen (Jonason and Webster, 2010. Previous Item Response Theory (IRT analyses of the original English Dark Triad Dirty Dozen have shown that all three subscales adequately tap into the dark domains of personality. The aim of the present study was to analyze the Swedish version of the Dark Triad Dirty Dozen using IRT. Method: 570 individuals (nmales = 326, nfemales = 242, and 2 unreported, including university students and white-collar workers with an age range between 19 and 65 years, responded to the Swedish version of the Dark Triad Dirty Dozen (Garcia et al., 2017a,b. Results: Contrary to previous research, we found that the narcissism scale provided most information, followed by psychopathy, and finally Machiavellianism. Moreover, the psychopathy scale required a higher level of the latent trait for endorsement of its items than the narcissism and Machiavellianism scales. Overall, all items provided reasonable amounts of information and are thus effective for discriminating between individuals. The mean item discriminations (alphas were 1.92 for Machiavellianism, 2.31 for narcissism, and 1.99 for psychopathy. Conclusion: This is the first study to provide IRT analyses of the Swedish version of the Dark Triad Dirty Dozen. Our findings add to a growing literature on the Dark Triad Dirty Dozen scale in different cultures and highlight psychometric characteristics, which can be used for comparative studies. Items tapping into psychopathy showed higher thresholds for endorsement than the other two scales. Importantly, the narcissism scale seems to provide more information about a lack of narcissism, perhaps mirroring cultural conditions. Keywords: Psychology, Psychiatry, Clinical psychology

  3. (irt) using bilog - mg v3.0 and irtpro v3.0 programmes

    African Journals Online (AJOL)

    Global Journal

    American Association of Educational Research,. American Psychological Association, and. National Council on Measurement in Education. (2014). Failure to meet this requirement invalidates the application of IRT in real data set evaluation. Researches (Orlando and Thissen,. 2000, 2003) indicated that model checking.

  4. Comparison of the 10x10 and the 8x6 Supersonic Wind Tunnels at the NASA Glenn Research Center for Low-Speed (Subsonic) Operation

    Science.gov (United States)

    Hoffman, Thomas R.; Johns, Albert L.; Bury, Mark E.

    2002-01-01

    NASA Glenn Research Center and Lockheed Martin tested an aircraft model in two wind tunnels to compare low-speed (subsonic) flow characteristics. Test objectives were to determine and document similarities and uniqueness of the tunnels and to verify that the 10- by 10-Foot Supersonic Wind Tunnel (10x10 SWT) is a viable low-speed test facility when compared to the 8- by 6-Foot Supersonic Wind Tunnel (8x6 SWT). Conclusions are that the data from the two facilities compares very favorably and that the 10-by 10-Foot Supersonic Wind Tunnel at NASA Glenn Research Center is a viable low-speed wind tunnel.

  5. Development of Delta Wing Aerodynamics Research in Universiti Teknologi Malaysia Low Speed Wind Tunnel

    Directory of Open Access Journals (Sweden)

    Shabudin Mat

    2014-07-01

    Full Text Available This paper presents wind tunnel experiment on two delta wing configurations which are differentiated by their leading edge profiles: sharp and round-edged wings. The experiments were performed as a part of the delta wing aerodynamics research development in Universiti Teknologi Malaysia, low speed tunnel (UTM-LST. Steady load balance and flow visualization tests were conducted at Reynolds numbers of 0.5, 1, and 1.5 × 106, respectively. The flow measurement at low Reynolds number was also performed at as low as speed of 5 m/s. During the experiments, laser with smoke flow visualizations test was performed on both wings. The study has identified interesting features of the interrelationship between the conventional leading edge primary vortex and the occurrence and development of the vortex breakdown above the delta wings. The results conclude the vortex characteristics are largely dependent on the Reynolds number, angle of attack, and leading-edge radii of the wing.

  6. Research capabilities of the NASA Langley 8-foot high temperature tunnel

    Science.gov (United States)

    Puster, Richard L.

    1991-01-01

    The NASA Langley Research Center's 8-Foot High Temperature Tunnel (8' HTT) has been modified to facilitate the testing of hypersonic airbreathing propulsion systems in addition to aerothermal load definition and structural concept verification at Mach 4, 5, and 7. The 8' HTT simulates flight from 60 to 125 kft with run times of 1 to 2 min. The 8-ft diameter and 12-ft-long free jet length enables the testing of large engines or multiple subscale engines. Methane and air combustion products provide the true temperature environment; an oxygen system enriches the combustion products to the same volume fraction of oxygen as air to enable the testing of airbreathing engines. A hydrogen system provides model fuel for cooling and combustion. High use tunnel components have been upgraded or replaced.

  7. A Bayesian Beta-Mixture Model for Nonparametric IRT (BBM-IRT)

    Science.gov (United States)

    Arenson, Ethan A.; Karabatsos, George

    2017-01-01

    Item response models typically assume that the item characteristic (step) curves follow a logistic or normal cumulative distribution function, which are strictly monotone functions of person test ability. Such assumptions can be overly-restrictive for real item response data. We propose a simple and more flexible Bayesian nonparametric IRT model…

  8. Blasting Impact by the Construction of an Underground Research Tunnel in KAERI

    International Nuclear Information System (INIS)

    Kwon, S.; Cho, W. J.

    2005-12-01

    The underground research tunnel, which is under construction in KAERI for the validation of HLW disposal system, is excavated by drill and blasting method using high-explosives. In order not to disturb the operation at the research facilities such as HANARO reactor, it is critical to develop a blasting design , which will not influence on the facilities, even though several tens of explosives are detonated almost simultaneously. To develop a reasonable blasting design, a test blasting at the site should be performed. A preliminary analysis for predicting the expected vibration and noise by the blasting for the construction of the underground research tunnel was performed using a typical empirical equation. From the study, a blasting design could be developed not to influence on the major research facilities in KAERI. For the validation of the blasting design, a test blasting was carried out at the site and the parameters of vibration equation could be determined using the measured data during the test blasting. Using the equation, it was possible to predict the vibration at different locations at KAERI and to conclude that the blasting design would meet the design criteria at the major facilities in KAERI. The study would verify the applicability of blasting method for the construction of a research tunnel in a rock mass and that would help the design and construction of large scale underground research laboratory, which might be carried out in the future. It is also meaningful to accumulate technical experience for enhancing the reliability and effectiveness of the design and construction of the HLW disposal repository, which will be constructed in deep underground by drill and blasting technique

  9. Radiation monitoring program at nuclear scientific experimental and educational center - IRT-Sofia

    International Nuclear Information System (INIS)

    Mladenov, A.; Stankov, D.; Marinov, K.; Nonova, T.; Krezhov, K.

    2012-01-01

    Ensuring minimal risk of personnel exposure without exceeding the dose limits is the main task of the General Program for Radiation Monitoring of Nuclear Scientific Experimental and Education Centre (NSEEC) with research reactor IRT. Since 2006 the IRT-Sofia is equipped with a new and modern Radiation Monitoring System (RMS). All RMS detectors are connected to the server RAMSYS. They have online (real-time) visualization in two workstations with RAMVISION software. The RMS allows the implementation of technological and environmental monitoring at the nuclear facility site. Environmental monitoring with the RMS external system includes monitoring of dose rate; alpha and beta activity; radon activity; Po-218, Po-214, Po-212 activity; gamma control of vehicles. Technological control of reactor gases includes: Alpha beta particulate monitor; Iodine monitor; Noble gases monitor; Stack flow monitor. The General Program based on the radiation monitoring system allows real-time monitoring and control of radiation parameters in the controlled area and provides for a high level of radiation protection of IRT staff and users of its facilities. This paper presents the technical and functional parameters of the radiation monitoring system and radiation protection activities within the restricted zone in IRT facilities. (authors)

  10. Determination of IRT-2M fuel burnup by gamma spectrometry.

    Science.gov (United States)

    Koleška, Michal; Viererbl, Ladislav; Marek, Milan; Ernest, Jaroslav; Šunka, Michal; Vinš, Miroslav

    2016-01-01

    A spectrometric system was developed for evaluating spent fuel in the LVR-15 research reactor, which employs highly enriched (36%) IRT-2M-type fuel. Such system allows the measurement of detailed fission product profiles. Within these measurements, nuclides such as (137)Cs, (134)Cs, (144)Ce, (106)Ru and (154)Eu may be detected in fuel assemblies with different cooling times varying between 1.67 and 7.53 years. Burnup calculations using the MCNPX Monte Carlo code data showed good agreement with measurements, though some discrepancies were observed in certain regions. These discrepancies are attributed to the evaluation of irradiation history, reactor regulation pattern and buildup schemes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. In-situ failure test in the research tunnel at Olkiluoto

    International Nuclear Information System (INIS)

    Autio, J.; Johansson, E.; Kirkkomaeki, T.; Hakala, M.; Heikkilae, E.

    2000-05-01

    A failure test suitable for execution in the Research Tunnel at Olkiluoto has been planned to study the failure of rock in-situ. The objectives of the in-situ failure test is to assess the applicability of numerical modelling codes and methods to the study of rock failure and associated crack propagation and to develop a novel technique to be used to determine the strength of rock in-situ. The objective of this study was to make a preliminary design of the failure test, assess the technical feasibility of the test and to give input information for further numerical modelling of the test. The design of the failure test is reported and results of preliminary modelling are given. The input information for future modelling includes a study of rock properties, fracture propagation in rock, in-situ stresses and the development of techniques for using the expanding agent to produce artificial stress field. The study showed that mechanical properties such as strength of gneissic tonalite, the main rock type in the Research Tunnel, depends highly on the orientation of schistocity. The in-situ failure test was shown to be technically feasible and a state of stress high enough to cause failure can be created artificially by using a proper expansive agent and design. (orig.)

  12. Thermal, hydraulic, and mechanical initial conditions around KAERI Underground Research Tunnel

    International Nuclear Information System (INIS)

    Kwon, S. K.; Cho, W. J.

    2009-07-01

    In KAERI underground research tunnel(KURT) various in situ experiments for the investigation of thermal, mechanical, hydraulic, and chemical behaviours related to the validation of high-level radioactive waste disposal system are carrying out. In this study, the geological characteristics, thermal, hydraulic, and mechanical(THM) properties of the rock mass, and groundwater level analyzed and derived relationship between the THM properties and depth. From this study, it was found that the THM properties varies with depth Z and many properties could be expressed well with an equation type, a+b/Z c . The calculated rock thermal properties were 3∼7% higher than the measurement and the difference was relatively higher in dry rock. With empirical equations and measured air and tunnel wall temperatures, it was also possible to estimate that the seasonal temperature variations at 5m and 10m distance from tunnel wall were 3 .deg. C and 0,75 .deg. C, respectively. The thermal-hydraulic-mechanical initial conditions around KURT derived from this study will be utilized for the selection of location and the design for various in situ experiments at KURT. Those will be also used as fundamental data for the analysis of the results from the in situ experiments. The understanding of the THM initial conditions will be useful for the investigation of low and intermediate level repository as well the site selection and system design for a temporary storage facility and a high-level radioactive waste repository. This will also be applied to the design of underground caverns for various purposes and the analysis of in situ measurements at underground excavations

  13. IRT-Sofia BNCT beam tube optimization study.

    Science.gov (United States)

    Belousov, S; Mitev, M; Ilieva, K; Riley, K; Harling, O

    2011-12-01

    An optimization study of IRT-Sofia BNCT beam tube is presented. In the study we used the MIT/FCB experience. The enlarging of filter/moderator cross section dimensions and the decreasing of collimator length within the limits of the IRT-Sofia reactor design were analyzed. The influence of beam and reactor core axes non-coincidence on the beam properties was also evaluated. The irradiation resistance of polytetrafluoroethylene (Teflon(®)) was also evaluated. The results provide information for making decisions on the IRT-Sofia BNCT beam construction. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Key Topics for High-Lift Research: A Joint Wind Tunnel/Flight Test Approach

    Science.gov (United States)

    Fisher, David; Thomas, Flint O.; Nelson, Robert C.

    1996-01-01

    Future high-lift systems must achieve improved aerodynamic performance with simpler designs that involve fewer elements and reduced maintenance costs. To expeditiously achieve this, reliable CFD design tools are required. The development of useful CFD-based design tools for high lift systems requires increased attention to unresolved flow physics issues. The complex flow field over any multi-element airfoil may be broken down into certain generic component flows which are termed high-lift building block flows. In this report a broad spectrum of key flow field physics issues relevant to the design of improved high lift systems are considered. It is demonstrated that in-flight experiments utilizing the NASA Dryden Flight Test Fixture (which is essentially an instrumented ventral fin) carried on an F-15B support aircraft can provide a novel and cost effective method by which both Reynolds and Mach number effects associated with specific high lift building block flows can be investigated. These in-flight high lift building block flow experiments are most effective when performed in conjunction with coordinated ground based wind tunnel experiments in low speed facilities. For illustrative purposes three specific examples of in-flight high lift building block flow experiments capable of yielding a high payoff are described. The report concludes with a description of a joint wind tunnel/flight test approach to high lift aerodynamics research.

  15. Analysis of a Near-field Earthquake Record at the Deep Underground Research Tunnel

    International Nuclear Information System (INIS)

    Yun, Kwan Hee; Park, Dong Hee; Shim, Taek Mo

    2009-01-01

    On October 29, 2008, a moderate earthquake (M=3.4, 36.35 N 127.25 E) occurred near the city of Daejon where an underground testing facilities called 'KURT (KAERI Underground Research Tunnel)' was located inside KAERI. Even though this earthquake did not trigger a seismic monitoring system of the mock-up Nuclear Power Plant of Hanaro, it was large enough not only to provide nation-wide earthquake data of good quality but also to be widely felt by the people uncomfortably around Daejon. In addition, this earthquake provides a good chance to obtain a nearfield broadband seismogram of frequency up to 200Hz recorded at the three-component geophones at the deep underground tunnel of the KURT (-90m). So we compared the seismic records from the KURT with other records from the nearby national seismic network to evaluate the earthquake ground-motion characteristics at the underground facilities for future engineering application. Three nearby seismic stations of the national seismic network jointly operated by Korea Meteorological Administration (KMA), Korea Institute of Geoscience And Mineral Resources (KIGAM), KEPRI, and KINS

  16. Developing a Fracture Model of the Granite Rocks Around the Research Tunnel at the Mizunami Underground Research Laboratory in Central Japan

    Science.gov (United States)

    Kalinina, E.; Hadgu, T.; Wang, Y.

    2017-12-01

    The Mizunami Underground Research Laboratory (MIU) is located in Tono area in Central Japan. It is operated by the Japan Atomic Energy Agency (JAEA) with the main purpose of providing scientific basis for the research and development of technologies needed for deep geological disposal of radioactive waste in fractured crystalline rocks. The current work is focused on the research and experiments in the tunnel located at 500 m depth. The data collected in the tunnel and exploratory boreholes were shared with the participants of the DEvelopment of COupled models and their VALidation against EXperiments (DECOVALEX), an international research and model comparison collaboration. This study describes the development of the fracture model representing granite rocks around the research tunnel. The model domain is 100x150x100m with the main experimental part of the tunnel, Closure Test Drift, located approximately in the center. The major input data were the fracture traces measured on the tunnel walls (total of 2,023 fractures), fractures observed in the horizontal borehole parallel to the tunnel, and the packer tests conducted in this borehole and one vertical borehole located within the modeling domain. 78 fractures (the ones with the inflow) in the tunnel were incorporated in the development of the fracture model. Fracture size was derived from the fracture trace analysis. It was shown that the fracture radius followed lognormal distributions. Fracture transmissivity was estimated from an analytical solution of inflow into the tunnel through an individual fracture and the total measured inflow into the tunnel. 16 fractures were incorporated in the model along the horizontal borehole. The packer test data in the different well intervals were used to estimate the range in fracture transmissivity. A relationship between the fracture transmissivity and fracture radius was developed. The fractures in the tunnel and borehole were used to derive fracture orientation and

  17. Application of multidimensional IRT models to longitudinal data

    NARCIS (Netherlands)

    te Marvelde, J.M.; Glas, Cornelis A.W.; Van Landeghem, Georges; Van Damme, Jan

    2006-01-01

    The application of multidimensional item response theory (IRT) models to longitudinal educational surveys where students are repeatedly measured is discussed and exemplified. A marginal maximum likelihood (MML) method to estimate the parameters of a multidimensional generalized partial credit model

  18. An underground research tunnel for the validation of high-level radioactive waste disposal concept

    International Nuclear Information System (INIS)

    Kwon, S.; Park, S. I.; Park, J. H.; Cho, W. J.; Han, P. S.

    2005-01-01

    In order to dispose of high-level radioactive waste(HLW) safely in geological formations, it is necessary to assess the feasibility, safety, appropriateness, and stability of the disposal concept at an underground research site, which is constructed in the same geological formation as the host rock. In this study, minimum requirements and the conceptual design for an efficient construction of a small scale URL, which is named URT, were derived based on a literature review. To confirm the validity of the conceptual design for construction at KAERI, a geological survey including a seismic refraction survey, electronic resistivity survey, borehole drilling, and in situ and laboratory tests were carried out. Based on the results, it was possible to design URT effectively with a consideration of the site characterization. The construction of URT was started in May 2005 and the first stage of the construction of the access tunnel could be successfully completed in Aug. 2005

  19. Characterization of Groundwater Colloids Sampled from KAERI Underground Research Tunnel (KURT)

    International Nuclear Information System (INIS)

    Baik, Min Hoon; Lee, Tae Yeop

    2011-01-01

    It has been reported that colloid formation of radionuclides by sorption of radionuclides on negatively charged naturally occurring colloidal matters can drastically increase the mobility of the radionuclides released from a radioactive waste repository. Therefore, the roles of colloids in the radionuclide migration could be very important in terms of safety assessment on a radioactive waste repository. To assess the effects of mobile natural colloids on the radionuclide migration in geological media, it is necessary to obtain information about colloid characteristics such as elemental composition, size distribution, and concentrations under relevant solution conditions. These properties determine the distribution of the radionuclide between the dissolved and the colloidal phases and the mobility of the radio-colloids in a considered migration medium. Therefore, in this study, physicochemical properties of natural groundwater colloids sampled from a deep granite groundwater in the KAERI Underground Research Tunnel (KURT) are investigated to characterize the behaviors of natural groundwater colloids in a deep granitic groundwater

  20. Solubility of neptunium oxide in the KURT (KAERI Underground Research Tunnel) groundwater

    International Nuclear Information System (INIS)

    Kim, S.S.; Baik, M.H.; Kang, K.C.

    2009-01-01

    The solubilities of NpO 2 (s) in the KURT (KAERI Underground Research Tunnel) granitic groundwater with low ionic strength were measured experimentally and calculated by a geochemical code. Then these results were compared with each other as well as with foreign results. The concentrations of neptunium were measured as 6 x 10 -8 - 2 x 10 -8 mol/L at a pH 9.5-11.1 and Eh = -0.2 V, and less than 5 x 10 -9 mol/L at a pH = 11.8-13.0 and Eh -0.3-0.44 V. The dominant aqueous species were presumed as Np(OH) x (CO 3 ) y 4-x-2y complexes and Np(OH) 4 (aq) at pH = 9.5-13 under the Eh<-0.2 V reducing condition. (author)

  1. Restoration of the Hypersonic Tunnel Facility at NASA Glenn Research Center, Plum Brook Station

    Science.gov (United States)

    Woodling, Mark A.

    2000-01-01

    The NASA Glenn Research Center's Hypersonic Tunnel Facility (HTF), located at the Plum Brook Station in Sandusky, Ohio, is a non-vitiated, free-jet facility, capable of testing large-scale propulsion systems at Mach Numbers from 5 to 7. As a result of a component failure in September of 1996, a restoration project was initiated in mid- 1997 to repair the damage to the facility. Following the 2-1/2 year effort, the HTF has been returned to an operational condition. Significant repairs and operational improvements have been implemented in order to ensure facility reliability and personnel safety. As of January 2000, this unique, state-of-the-art facility was ready for integrated systems testing.

  2. Hydraulic and tracer experiments in the TVO research tunnel 1993- 1994

    International Nuclear Information System (INIS)

    Hautojaervi, A.; Ilvonen, M.; Vieno, T.; Viitanen, P.

    1995-04-01

    Three full-size deposition holes (diameter 1.5 m, depth 7.5 m) for spent fuel canisters in a KBS-3 type repository have been bored with a new fullface boring method in the TVO Research Tunnel. The Research Tunnel lies in the crystalline bedrock at the depth of 60 metres in the VLJ Repository for low and medium level waste. The holes are 6 metres apart. The boring tests were accompanied by comprehensive pre- and post-characterization of the rock and the bored wells. The inflow rates of groundwater in two of the three full-size holes are 6 and 20 litres/hour. The well in the middle is almost dry as expected on the basis of the pre-characterization. In the tracer tests two different tracers, a dye and a radioactive tracer, were used at the same time. The comprehensive data analysis performed showed that novel techniques (e.g. Extreme Value Estimation, EVE) can be successfully applied to determine the impulse response from the experimental results even in cases where the measured signals are disturbed. Hydraulic and tracer tests as well as visual inspection of the inflow gave clear indications of flow and transport in sparse and narrow channels. Transport velocities could be predicted with a reasonable accuracy by using a simple concept of fracture cavities determining the transport time and 'bottlenecks' causing the hydraulic resistance. The observed non-Fickian dispersion is thought to be caused by velocity differences over the channel width or by diffusion into stagnant pools in the fracture filling. (orig.) (36 refs., 67 figs., 1 tab.)

  3. Comparison of the NASA Common Research Model European Transonic Wind Tunnel Test Data to NASA Test Data

    Science.gov (United States)

    Rivers, Melissa; Quest, Juergen; Rudnik, Ralf

    2015-01-01

    Experimental aerodynamic investigations of the NASA Common Research Model have been conducted in the NASA Langley National Transonic Facility, the NASA Ames 11-ft wind tunnel, and the European Transonic Wind Tunnel. In the NASA Ames 11-ft wind tunnel, data have been obtained at only a chord Reynolds number of 5 million for a wing/body/tail = 0 degree incidence configuration. Data have been obtained at chord Reynolds numbers of 5, 19.8 and 30 million for the same configuration in the National Transonic Facility and in the European Transonic Facility. Force and moment, surface pressure, wing bending and twist, and surface flow visualization data were obtained in all three facilities but only the force and moment and surface pressure data are presented herein.

  4. Pretest-Posttest-Posttest Multilevel IRT Modeling of Competence Growth of Students in Higher Education in Germany

    NARCIS (Netherlands)

    Schmidt, Susanne; Zlatkin-Troitschanskaia, Olga; Fox, Gerardus J.A.

    2016-01-01

    Longitudinal research in higher education faces several challenges. Appropriate methods of analyzing competence growth of students are needed to deal with those challenges and thereby obtain valid results. In this article, a pretest-posttest-posttest multivariate multilevel IRT model for repeated

  5. Vulnerability Analysis of Soft Caving Tunnel Support System and Surrounding Rock Optimal Control Technology Research

    Directory of Open Access Journals (Sweden)

    Ming Ji

    2014-01-01

    Full Text Available The vulnerability assessment model, composed by 11 vulnerability factors, is established with the introduction of the concept of “vulnerability” into the assessment of tunnel support system. Analytic hierarchy process is utilized to divide these 11 factors into human attributes and natural attributes, and define the weight of these factors for the model. The “vulnerability” applied io the assessment of the tunnel support system model is reached. The vulnerability assessment model was used for evaluating and modifying the haulage tunnel #3207 of Bo-fang mine panel #2. The results decreased the vulnerability of the tunnel support system and demonstrated acceptable effects. Furthermore, the results show that the impact of human attributes on tunnel support systems is dramatic under the condition that natural attributes are permanent, and the “vulnerability” is exactly a notable factor to manifest the transformation during this process. The results also indicate that optimizing human attributes can attenuate vulnerability in tunnel support systems. As a result, enhancement of stability of tunnel support systems can be achieved.

  6. The Research on Tunnel Surrounding Rock Classification Based on Geological Radar and Probability Theory

    Science.gov (United States)

    Xiao Yong, Zhao; Xin, Ji Yong; Shuang Ying, Zuo

    2018-03-01

    In order to effectively classify the surrounding rock types of tunnels, a multi-factor tunnel surrounding rock classification method based on GPR and probability theory is proposed. Geological radar was used to identify the geology of the surrounding rock in front of the face and to evaluate the quality of the rock face. According to the previous survey data, the rock uniaxial compressive strength, integrity index, fissure and groundwater were selected for classification. The related theories combine them into a multi-factor classification method, and divide the surrounding rocks according to the great probability. Using this method to classify the surrounding rock of the Ma’anshan tunnel, the surrounding rock types obtained are basically the same as those of the actual surrounding rock, which proves that this method is a simple, efficient and practical rock classification method, which can be used for tunnel construction.

  7. Calibration of the Flow in the Test Section of the Research Wind Tunnel at DST Group

    Science.gov (United States)

    2015-10-01

    the tunnel. The calibration data are presented and analysed and explanations of flow behaviour are given. 2. Mean-Velocity Measurements 2.1...1073. Defence Science and Technology Organisation , Melbourne, Australia. Erm, L. P. 2003 Calibration of the flow in the extended test section...of the low-speed wind tunnel at DSTO. DSTO-TR-1384. Defence Science and Technology Organisation , Melbourne, Australia. Erm, L. P. 2015

  8. A neutron radiography facility on the IRT-2000 reactor

    International Nuclear Information System (INIS)

    Khadduri, I.Y.

    1976-01-01

    A neutron radiography facility has been constructed on the thermal neutron channel of the IRT-2000 reactor. A collimated thermal neutron beam exposure area of 10 cm diameter is obtained with an L/D ratio of 48.8. The film used is cellulose nitrate coated with lithium tetraborate which is insensitive to gamma and beta radiation. Some pictures with good contrast and resolution have been obtained. Pictures of parts of an IRT-2000 reactor fuel pin have also been recorded. (orig) [de

  9. Ground penetrating radar measurements at the ONKALO research tunnel and eastern part of the Olkiluoto investigation area at July 2006

    International Nuclear Information System (INIS)

    Sipola, V.; Tarvainen, A.-M.

    2007-04-01

    Ground Penetrating Radar (GPR) measurements were carried out at ONKALO research site in summer 2006. Measurements included 400 metres of measurements inside ONKALO access tunnel and about 1800 metres of measurements on the ground, at the eastern parts of Olkiluoto investigation area. The purpose of the measurements done inside the access tunnel was to investigate, whether it would be possible to locate deformation structures or long fractures in the rock mass below the tunnel. The purpose of the measurements made on top of the ground was to investigate, whether it would be possible to locate glacio-isostatic faults from the soils. A secondary target was to try and locate the rock surface. The chosen part of ONKALO tunnel was measured using five different frequencies, which enabled comparing the results to each other. It also enabled getting a higher resolution picture of the top rock, than what would have been possible using only one low-frequency antenna. The on-the-ground measurements were measured using only one frequency. (orig.)

  10. The Exploration of the Relationship between Guessing and Latent Ability in IRT Models

    Science.gov (United States)

    Gao, Song

    2011-01-01

    This study explored the relationship between successful guessing and latent ability in IRT models. A new IRT model was developed with a guessing function integrating probability of guessing an item correctly with the examinee's ability and the item parameters. The conventional 3PL IRT model was compared with the new 2PL-Guessing model on…

  11. IRT Model Misspecification and Measurement of Growth in Vertical Scaling

    Science.gov (United States)

    Bolt, Daniel M.; Deng, Sien; Lee, Sora

    2014-01-01

    Functional form misfit is frequently a concern in item response theory (IRT), although the practical implications of misfit are often difficult to evaluate. In this article, we illustrate how seemingly negligible amounts of functional form misfit, when systematic, can be associated with significant distortions of the score metric in vertical…

  12. Loglinear multidimensional IRT models for polytomously scired Items

    NARCIS (Netherlands)

    Kelderman, Henk

    1988-01-01

    A loglinear item response theory (IRT) model is proposed that relates polytomously scored item responses to a multidimensional latent space. Each item may have a different response function where each item response may be explained by one or more latent traits. Item response functions may follow a

  13. A method for designing IRT-based item banks

    NARCIS (Netherlands)

    Boekkooi-Timminga, Ellen

    1990-01-01

    Since 1985 several procedures for computerized test construction using linear programing techniques have been described in the literature. To apply these procedures successfully, suitable item banks are needed. The problem of designing item banks based on item response theory (IRT) is addressed. A

  14. Bayesian Estimation of the Logistic Positive Exponent IRT Model

    Science.gov (United States)

    Bolfarine, Heleno; Bazan, Jorge Luis

    2010-01-01

    A Bayesian inference approach using Markov Chain Monte Carlo (MCMC) is developed for the logistic positive exponent (LPE) model proposed by Samejima and for a new skewed Logistic Item Response Theory (IRT) model, named Reflection LPE model. Both models lead to asymmetric item characteristic curves (ICC) and can be appropriate because a symmetric…

  15. Bayesian estimation of a multilevel IRT model using gibbs sampling

    NARCIS (Netherlands)

    Fox, Gerardus J.A.; Glas, Cornelis A.W.

    In this article, a two-level regression model is imposed on the ability parameters in an item response theory (IRT) model. The advantage of using latent rather than observed scores as dependent variables of a multilevel model is that it offers the possibility of separating the influence of item

  16. A Multilevel Mixture IRT Model with an Application to DIF

    Science.gov (United States)

    Cho, Sun-Joo; Cohen, Allan S.

    2010-01-01

    Mixture item response theory models have been suggested as a potentially useful methodology for identifying latent groups formed along secondary, possibly nuisance dimensions. In this article, we describe a multilevel mixture item response theory (IRT) model (MMixIRTM) that allows for the possibility that this nuisance dimensionality may function…

  17. Prior distributions for item parameters in IRT models

    NARCIS (Netherlands)

    Matteucci, M.; S. Mignani, Prof.; Veldkamp, Bernard P.

    2012-01-01

    The focus of this article is on the choice of suitable prior distributions for item parameters within item response theory (IRT) models. In particular, the use of empirical prior distributions for item parameters is proposed. Firstly, regression trees are implemented in order to build informative

  18. Research and application of highway tunnel fire alarm system based on fiber Bragg grating sensor technology

    Science.gov (United States)

    Zhou, Ciming; Chen, Liuyong; Jiang, Desheng; He, Jun; Zhang, Shaoyun

    2007-01-01

    A new fire alarm system based on FBG sensor has been investigated to determine its potential in fire alarm applications for highway tunnel. The system has been experimentally tested and some of its application are reported. The results show that the new fire alarm system is capable of fixed temperature alarm and rate-of-rise alarm promptly; the fire place can easily determined according to the location of maximum temperature; the temperature distribution and the rule of temperature development in the tunnel can be obtained at the same time.

  19. Mapping Fractures in KAERI Underground Research Tunnel using Ground Penetrating Radar

    Science.gov (United States)

    Baek, Seung-Ho; Kim, Seung-Sep; Kwon, Jang-Soon

    2016-04-01

    The proportion of nuclear power in the Republic of Korea occupies about 40 percent of the entire electricity production. Processing or disposing nuclear wastes, however, remains one of biggest social issues. Although low- and intermediate-level nuclear wastes are stored temporarily inside nuclear power plants, these temporary storages can last only up to 2020. Among various proposed methods for nuclear waste disposal, a long-term storage using geologic disposal facilities appears to be most highly feasible. Geological disposal of nuclear wastes requires a nuclear waste repository situated deep within a stable geologic environment. However, the presence of small-scale fractures in bedrocks can cause serious damage to durability of such disposal facilities because fractures can become efficient pathways for underground waters and radioactive wastes. Thus, it is important to find and characterize multi-scale fractures in bedrocks hosting geologic disposal facilities. In this study, we aim to map small-scale fractures inside the KAERI Underground Research Tunnel (KURT) using ground penetrating radar (GPR). The KURT is situated in the Korea Atomic Energy Research Institute (KAERI). The survey target is a section of wall cut by a diamond grinder, which preserves diverse geologic features such as dykes. We conducted grid surveys on the wall using 500 MHz and 1000 MHz pulseEKKO PRO sensors. The observed GPR signals in both frequencies show strong reflections, which are consistent to form sloping planes. We interpret such planar features as fractures present in the wall. Such fractures were also mapped visually during the development of the KURT. We confirmed their continuity into the wall from the 3D GPR images. In addition, the spatial distribution and connectivity of these fractures are identified from 3D subsurface images. Thus, we can utilize GPR to detect multi-scale fractures in bedrocks, during and after developing underground disposal facilities. This study was

  20. Mechanical design of a rotary balance system for NASA. Langley Research Center's vertical spin tunnel

    Science.gov (United States)

    Allred, J. W.; Fleck, V. J.

    1992-01-01

    A new lightweight Rotary Balance System is presently being fabricated and installed as part of a major upgrade to the existing 20 Foot Vertical Spin Tunnel. This upgrade to improve model testing productivity of the only free spinning vertical wind tunnel includes a modern fan/drive and tunnel control system, an updated video recording system, and the new rotary balance system. The rotary balance is a mechanical apparatus which enables the measurement of aerodynamic force and moment data under spinning conditions (100 rpm). This data is used in spin analysis and is vital to the implementation of large amplitude maneuvering simulations required for all new high performance aircraft. The new rotary balance system described in this report will permit greater test efficiency and improved data accuracy. Rotary Balance testing with the model enclosed in a tare bag can also be performed to obtain resulting model forces from the spinning operation. The rotary balance system will be stored against the tunnel sidewall during free flight model testing.

  1. Air Flow Modeling in the Wind Tunnel of the FHWA Aerodynamics Laboratory at Turner-Fairbank Highway Research Center

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, M. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Transportation Research and Analysis Computing Center (TRACC) Energy Systems Division; Lottes, S. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Transportation Research and Analysis Computing Center (TRACC) Energy Systems Division; Bojanowski, C. [Argonne National Lab. (ANL), Argonne, IL (United States). Transportation Research and Analysis Computing Center (TRACC) Energy Systems Division

    2017-09-01

    Computational fluid dynamics (CFD) modeling is widely used in industry for design and in the research community to support, compliment, and extend the scope of experimental studies. Analysis of transportation infrastructure using high performance cluster computing with CFD and structural mechanics software is done at the Transportation Research and Analysis Computing Center (TRACC) at Argonne National Laboratory. These resources, available at TRACC, were used to perform advanced three-dimensional computational simulations of the wind tunnel laboratory at the Turner-Fairbank Highway Research Center (TFHRC). The goals were to verify the CFD model of the laboratory wind tunnel and then to use versions of the model to provide the capability to (1) perform larger parametric series of tests than can be easily done in the laboratory with available budget and time, (2) to extend testing to wind speeds that cannot be achieved in the laboratory, and (3) to run types of tests that are very difficult or impossible to run in the laboratory. Modern CFD software has many physics models and domain meshing options. Models, including the choice of turbulence and other physics models and settings, the computational mesh, and the solver settings, need to be validated against measurements to verify that the results are sufficiently accurate for use in engineering applications. The wind tunnel model was built and tested, by comparing to experimental measurements, to provide a valuable tool to perform these types of studies in the future as a complement and extension to TFHRC’s experimental capabilities. Wind tunnel testing at TFHRC is conducted in a subsonic open-jet wind tunnel with a 1.83 m (6 foot) by 1.83 m (6 foot) cross section. A three component dual force-balance system is used to measure forces acting on tested models, and a three degree of freedom suspension system is used for dynamic response tests. Pictures of the room are shown in Figure 1-1 to Figure 1-4. A detailed CAD

  2. Recent Research Status on the Microbes in the Radioactive Waste Disposal and Identification of Aerobic Microbes in a Groundwater Sampled from the KAERI Underground Research Tunnel(KURT)

    International Nuclear Information System (INIS)

    Baik, Min Hoon; Lee, Seung Yeop; Cho, Won Jin

    2006-11-01

    In this report, a comprehensive review on the research results and status for the various effects of microbes in the radioactive waste disposal including definition and classification of microbes, and researches related with the waste containers, engineered barriers, natural barriers, natural analogue studies, and radionuclide migration and retardation. Cultivation, isolation, and classification of aerobic microbes found in a groundwater sampled from the KAERI Underground Research Tunnel (KURT) located in the KAERI site have carried out and over 20 microbes were found to be present in the groundwater. Microbial identification by a 16S rDNA genetic analysis of the selected major 10 aerobic microbes was performed and the identified microbes were characterized

  3. Manufacture, Installation and Operation of an In-situ Solute Migration System in KAERI Underground Research Tunnel (KURT)

    International Nuclear Information System (INIS)

    Lee, Jae Kwang; Baik, Min Hoon

    2009-07-01

    This report describes the design, installation, operation and maintenance of the in-situ solute migration system (IMS) which was installed in KAERI underground research tunnel (KURT) for the in-situ investigation of the solute migration. The IMS is consisted of the injection part, the extraction part, the measurement part, and the packer gas controlling system. The IMS was designed to measure the properties of the KURT groundwater in real time, which includes pH, redox potential, dissolved oxygen, electrical conductivity, and temperature. the remote control system was established to control the data processing unit through the internet

  4. The Mothball, Sustainment, and Proposed Reactivation of the Hypersonic Tunnel Facility (HTF) at NASA Glenn Research Center Plum Brook Station

    Science.gov (United States)

    Thomas, Scott R.; Lee, Jinho; Stephens, John W.; Hostler, Robert W., Jr.; VonKamp, William D.

    2010-01-01

    The Hypersonic Tunnel Facility (HTF) located at the NASA Glenn Research Center s Plum Brook Station in Sandusky, Ohio, is the nation s only large-scale, non-vitiated, hypersonic propulsion test facility. The HTF, with its 4-story graphite induction heater, is capable of duplicating Mach 5, 6, and 7 flight conditions. This unique propulsion system test facility has experienced several standby and reactivation cycles. The intent of the paper is to overview the HTF capabilities to the propulsion community, present the current status of HTF, and share the lessons learned from putting a large-scale facility into mothball status for a later restart

  5. Thermal and Pressure Characterization of a Wind Tunnel Force Balance Using the Single Vector System. Experimental Design and Analysis Approach to Model Pressure and Temperature Effects in Hypersonic Wind Tunnel Research

    Science.gov (United States)

    Lynn, Keith C.; Commo, Sean A.; Johnson, Thomas H.; Parker, Peter A,

    2011-01-01

    Wind tunnel research at NASA Langley Research Center s 31-inch Mach 10 hypersonic facility utilized a 5-component force balance, which provided a pressurized flow-thru capability to the test article. The goal of the research was to determine the interaction effects between the free-stream flow and the exit flow from the reaction control system on the Mars Science Laboratory aeroshell during planetary entry. In the wind tunnel, the balance was exposed to aerodynamic forces and moments, steady-state and transient thermal gradients, and various internal balance cavity pressures. Historically, these effects on force measurement accuracy have not been fully characterized due to limitations in the calibration apparatus. A statistically designed experiment was developed to adequately characterize the behavior of the balance over the expected wind tunnel operating ranges (forces/moments, temperatures, and pressures). The experimental design was based on a Taylor-series expansion in the seven factors for the mathematical models. Model inversion was required to calculate the aerodynamic forces and moments as a function of the strain-gage readings. Details regarding transducer on-board compensation techniques, experimental design development, mathematical modeling, and wind tunnel data reduction are included in this paper.

  6. Variance decomposition using an IRT measurement model.

    NARCIS (Netherlands)

    van den Berg, S.M.; Glas, C.A.W.; Boomsma, D.I.

    2007-01-01

    Large scale research projects in behaviour genetics and genetic epidemiology are often based on questionnaire or interview data. Typically, a number of items is presented to a number of subjects, the subjects' sum scores on the items are computed, and the variance of sum scores is decomposed into a

  7. M2-F1 mounted in NASA Ames Research Center 40x80 foot wind tunnel

    Science.gov (United States)

    1962-01-01

    After the first attempted ground-tow tests of the M2-F1 in March 1963, the vehicle was taken to the Ames Research Center, Mountain View, CA, for wind-tunnel testing. During these tests, Milt Thompson and others were in the M2-F1 to position the control surfaces for each test. The wingless, lifting body aircraft design was initially conceived as a means of landing an aircraft horizontally after atmospheric reentry. The absence of wings would make the extreme heat of re-entry less damaging to the vehicle. In 1962, Dryden management approved a program to build a lightweight, unpowered lifting body as a prototype to flight test the wingless concept. It would look like a 'flying bathtub,' and was designated the M2-F1, the 'M' referring to 'manned' and 'F' referring to 'flight' version. It featured a plywood shell placed over a tubular steel frame crafted at Dryden. Construction was completed in 1963. The first flight tests of the M2-F1 were over Rogers Dry Lake at the end of a tow rope attached to a hopped-up Pontiac convertible driven at speeds up to about 120 mph. This vehicle needed to be able to tow the M2-F1 on the Rogers Dry Lakebed adjacent to NASA's Flight Research Center (FRC) at a minimum speed of 100 miles per hour. To do that, it had to handle the 400-pound pull of the M2-F1. Walter 'Whitey' Whiteside, who was a retired Air Force maintenance officer working in the FRC's Flight Operations Division, was a dirt-bike rider and hot-rodder. Together with Boyden 'Bud' Bearce in the Procurement and Supply Branch of the FRC, Whitey acquired a Pontiac Catalina convertible with the largest engine available. He took the car to Bill Straup's renowned hot-rod shop near Long Beach for modification. With a special gearbox and racing slicks, the Pontiac could tow the 1,000-pound M2-F1 110 miles per hour in 30 seconds. It proved adequate for the roughly 400 car tows that got the M2-F1 airborne to prove it could fly safely and to train pilots before they were towed behind a C

  8. Monitoring pilot projects on bored tunnelling : The Second Heinenoord Tunnel and the Botlek Rail Tunnel

    NARCIS (Netherlands)

    Bakker, K.J.; De Boer, F.; Admiraal, J.B.M.; Van Jaarsveld, E.P.

    1999-01-01

    Two pilot projects for bored tunnelling in soft soil have been undertaken in the Netherlands. The monitoring was commissioned under the authority of the Centre for Underground Construction (COB). A description of the research related to the Second Heinenoord Tunnel and the Botlek Rail Tunnel will be

  9. Settlement Impact Analysis and Countermeasure Research of the Down Traversing Formed by the Double-Arch Subway Tunnels through the Existing Railways in Loess Area

    Directory of Open Access Journals (Sweden)

    Wang Lixin

    2015-01-01

    Full Text Available With the large-scale construction of city subways, the down traversing formed by subway running tunnels through the existing railways or railway yards are increasing day by day. Down traversing in shield method becomes common; however, the engineering cases which can be referable in the down traversing formed by the shallow-buried excavation of double-arch tunnels through the existing railways are very little. The ability to effectively control the excavation of shallow-buried subway tunnels can directly affect the safety of railway operation. According to the engineering characteristics of the down traversing formed by the shallow-buried excavation of double-arch tunnels in loessial layer, this paper proposed the standards for railway bed and track settlement control, and offers underground water treatment measures with assistant steps implemented on the ground surface during construction, so as to ensure the railway operation safety during the construction of the tunnel. Moreover, this paper applied MIDAS-GTS finite element software to make numerical simulation analysis of the down traversing formed by the double-arch tunnel through the railway and obtained the deformation laws during down traversing. The calculations suggest the railway track deformation caused by the down traversing construction of the double-arch tunnel in this project can meet related control standard requirements. There’s certain reference value contained in the deformation laws for the point locations of monitoring measurement. The research conclusions can provide scientific proof and technical guidance for the design and construction of this running tunnel project in order to offer reference for similar projects in the future.

  10. Radiation conditions at the training IRT-2000 and IR-100 reactors

    International Nuclear Information System (INIS)

    Fedorin, Eh.V.; Bronshtejn, I.Eh; Martynov, Yu.N.; Chistyakov, N.I.

    1978-01-01

    The experience is reviewed of radiation hygiene surveys and radiation safety provision during instructional processes on two training and research nuclear reactors of the IRT-2000 type (No. 1 and No. 2) and on an IR-200 reactor. From an analysis of individual dosimetry data the conclusion is made that the trainees and personnel are exposed mainly to external gamma-radiation and also, to a minor degree, to thermal neutrons and beta-radiation. It has been found that a high level of radiation safety is ensured on the training and research so that research and instruction activities are conducted at annual levels of exposure substantially lower than 0.5 rem in the case of trainees and 5 rem in the case of personnel

  11. Consequences of different diagnostic "gold standards" in test accuracy research: Carpal Tunnel Syndrome as an example.

    Science.gov (United States)

    Bachmann, Lucas M; Jüni, Peter; Reichenbach, Stephan; Ziswiler, Hans-Rudolf; Kessels, Alfons G; Vögelin, Esther

    2005-08-01

    Test accuracy studies assume the existence of a well-defined illness definition and clear-cut diagnostic gold standards or reference standards. However, in clinical reality illness definitions may be vague or a mere description of a set of manifestations, mostly clinical signs and symptoms. This can lead to disagreements among experts about the correct classification of an illness and the adequate reference standard. Using data from a diagnostic accuracy study in carpal tunnel syndrome, we explored the impact of different definitions on the estimated test accuracy and found that estimated test performance characteristics varied considerably depending on the chosen reference standard. In situations without a clear-cut illness definition, randomized controlled trials may be preferable to test accuracy studies for the evaluation of a novel test. These studies do not determine the diagnostic accuracy, but the clinical impact of a novel test on patient management and outcome.

  12. Tunnel fire dynamics

    CERN Document Server

    Ingason, Haukur; Lönnermark, Anders

    2015-01-01

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

  13. Pressure-Sensitive Paint Measurements on the NASA Common Research Model in the NASA 11-ft Transonic Wind Tunnel

    Science.gov (United States)

    Bell, James H.

    2011-01-01

    The luminescence lifetime technique was used to make pressure-sensitive paint (PSP) measurements on a 2.7% Common Research Model in the NASA Ames 11ft Transonic Wind Tunnel. PSP data were obtained on the upper and lower surfaces of the wing and horizontal tail, as well as one side of the fuselage. Data were taken for several model attitudes of interest at Mach numbers between 0.70 and 0.87. Image data were mapped onto a three-dimensional surface grid suitable both for comparison with CFD and for integration of pressures to determine loads. Luminescence lifetime measurements were made using strobed LED (light-emitting diode) lamps to illuminate the PSP and fast-framing interline transfer cameras to acquire the PSP emission.

  14. Local structural displacements across the structural phase transition in IrTe2: Order-disorder of dimers and role of Ir-Te correlations

    Science.gov (United States)

    Joseph, B.; Bendele, M.; Simonelli, L.; Maugeri, L.; Pyon, S.; Kudo, K.; Nohara, M.; Mizokawa, T.; Saini, N. L.

    2013-12-01

    We have studied local structure of IrTe2 by Ir L3-edge extended x-ray absorption fine structure (EXAFS) measurements as a function of temperature to investigate origin of the observed structural phase transition at Ts˜270 K. The EXAFS results show an appearance of longer Ir-Te bond length (ΔR ˜0.05 Å) at T IrTe2 should be an order-disorder-like transition of Ir-Ir dimers assisted by Ir-Te bond correlations, thus indicating important role of the interaction between the Ir 5d and Te 5p orbitals in this transition.

  15. Tunneling features in semiconductor nanostructures

    Science.gov (United States)

    Arseev, P. I.; Mantsevich, V. N.; Maslova, N. S.; Panov, V. I.

    2017-11-01

    The most telling scanning tunneling microscopy/spectroscopy (STM/STS) data available on the influence of nonequilibrium tunneling effects and electronic spectra reconstruction are reviewed and theoretically explained by self-consistently accounting for nonequilibrium electron distribution and the change (due to the tunneling current) in the electron density of states near the tunneling junction. The paper discusses the basic ideas of the self-consistent tunneling theory, which forms the basis for experimental research and which allows many effects observed in STM/STS experiments to be explained and new phenomena to be predicted.

  16. Detection of Differential Item Functioning with Nonlinear Regression: A Non-IRT Approach Accounting for Guessing

    Science.gov (United States)

    Drabinová, Adéla; Martinková, Patrícia

    2017-01-01

    In this article we present a general approach not relying on item response theory models (non-IRT) to detect differential item functioning (DIF) in dichotomous items with presence of guessing. The proposed nonlinear regression (NLR) procedure for DIF detection is an extension of method based on logistic regression. As a non-IRT approach, NLR can…

  17. IRT-Stimulus Contingencies in Chained Schedules: Implications for the Concept of Conditioned Reinforcement

    Science.gov (United States)

    Bejarano, Rafael; Hackenberg, Timothy D.

    2007-01-01

    Two experiments with pigeons investigated the effects of contingencies between interresponse times (IRTs) and the transitions between the components of 2- and 4-component chained schedules (Experiments 1 and 2, respectively). The probability of component transitions varied directly with the most recent (Lag 0) IRT in some experimental conditions…

  18. Examining Differential Item Functioning: IRT-Based Detection in the Framework of Confirmatory Factor Analysis

    Science.gov (United States)

    Dimitrov, Dimiter M.

    2017-01-01

    This article offers an approach to examining differential item functioning (DIF) under its item response theory (IRT) treatment in the framework of confirmatory factor analysis (CFA). The approach is based on integrating IRT- and CFA-based testing of DIF and using bias-corrected bootstrap confidence intervals with a syntax code in Mplus.

  19. A Combined IRT and SEM Approach for Individual-Level Assessment in Test-Retest Studies

    Science.gov (United States)

    Ferrando, Pere J.

    2015-01-01

    The standard two-wave multiple-indicator model (2WMIM) commonly used to analyze test-retest data provides information at both the group and item level. Furthermore, when applied to binary and graded item responses, it is related to well-known item response theory (IRT) models. In this article the IRT-2WMIM relations are used to obtain additional…

  20. Some Observations on the Identification and Interpretation of the 3PL IRT Model

    Science.gov (United States)

    Azevedo, Caio Lucidius Naberezny

    2009-01-01

    The paper by Maris, G., & Bechger, T. (2009) entitled, "On the Interpreting the Model Parameters for the Three Parameter Logistic Model," addressed two important questions concerning the three parameter logistic (3PL) item response theory (IRT) model (and in a broader sense, concerning all IRT models). The first one is related to the model…

  1. INCAS TRISONIC WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Florin MUNTEANU

    2009-09-01

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

  2. Investigation on F/M material aspects of IRT-Sofia NCT channel.

    Science.gov (United States)

    Mitev, M; Belousov, S; Ilieva, K

    2014-06-01

    The filter/moderator area of IRT-Sofia BNCT channel was investigated in this study in order to find a higher radiation resistant material as a suitable substitution for the Teflon(®). Two options - Al2O3 and graphite - were investigated. The results show, that both graphite and the Al2O3 can be successfully used as a filter/moderator material at IRT-Sofia. Initial evaluation of the in-phantom performance of the IRT-Sofia BNCT channel was made and merits similar to the best existing ones were found. © 2013 Elsevier Ltd. All rights reserved.

  3. Influence of Radon Radionuclide for the Development of an Ultra-Low Background Gamma Spectrometer in an Underground Research Tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wanno; Choi, Sangdo; Kim, Kyungsoo; Kang, Munja; Choi, Geunsik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    Installation in an underground level is very good to reduce the background induced by cosmic rays. A system in a surface laboratory is difficult to achieve enough reduction of the background, and an underground system has one main disadvantage in that researchers or workers are inconvenienced in accessing from office to laboratory, even though the background reduction is enough. KAERI (Korea Atomic Energy Research Institute) has performed ultra low-level background spectrometry using an active and passive shield at a surface laboratory. Based on our research experience of ultra-low level background system at a surface laboratory for many years, an underground gamma-ray spectrometry system is more effective for background reduction, but convenient access to an underground laboratory should be considered. The KAERI Underground Research Tunnel (KURT) is an infrastructure for a validation of the high-level waste disposal technology, which is located at a small mountain of KAERI. The geology of this mountain is composed primarily of granite. The ultra-low background system with passive and active shielding at KURT is developed, which is located underground with 156 m of water-equivalent below a surface level. Here, the influence of radon radionuclide is studied to test the performance of the developed system. Firstly, the background increase by radon radionuclide is examined, and secondly, a radiological dose assessment via radon radionuclides is evaluated. Underground radon concentration of day time with ventilation is similar with that of a ground laboratory. Therefore the background increase by radon will be solved using ventilation. Extra dose exposure by radon can be negligible in the day but time without ventilation has some problems. So the ventilation system for the experiment period in underground laboratory should be operated in order to protect extra dose exposure.

  4. Influence of Radon Radionuclide for the Development of an Ultra-Low Background Gamma Spectrometer in an Underground Research Tunnel

    International Nuclear Information System (INIS)

    Lee, Wanno; Choi, Sangdo; Kim, Kyungsoo; Kang, Munja; Choi, Geunsik

    2013-01-01

    Installation in an underground level is very good to reduce the background induced by cosmic rays. A system in a surface laboratory is difficult to achieve enough reduction of the background, and an underground system has one main disadvantage in that researchers or workers are inconvenienced in accessing from office to laboratory, even though the background reduction is enough. KAERI (Korea Atomic Energy Research Institute) has performed ultra low-level background spectrometry using an active and passive shield at a surface laboratory. Based on our research experience of ultra-low level background system at a surface laboratory for many years, an underground gamma-ray spectrometry system is more effective for background reduction, but convenient access to an underground laboratory should be considered. The KAERI Underground Research Tunnel (KURT) is an infrastructure for a validation of the high-level waste disposal technology, which is located at a small mountain of KAERI. The geology of this mountain is composed primarily of granite. The ultra-low background system with passive and active shielding at KURT is developed, which is located underground with 156 m of water-equivalent below a surface level. Here, the influence of radon radionuclide is studied to test the performance of the developed system. Firstly, the background increase by radon radionuclide is examined, and secondly, a radiological dose assessment via radon radionuclides is evaluated. Underground radon concentration of day time with ventilation is similar with that of a ground laboratory. Therefore the background increase by radon will be solved using ventilation. Extra dose exposure by radon can be negligible in the day but time without ventilation has some problems. So the ventilation system for the experiment period in underground laboratory should be operated in order to protect extra dose exposure

  5. Investigation of the development and the effect of an excavation damaged zone at KAERI underground research tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, S.; Cho, W. J

    2008-01-15

    The understanding of the long term behavior of rock around an underground radioactive waste repository is essential for the safe design and operation of the repository and for assuring the safety and technical feasibility of geological disposal concept. The investigation of the influence of EDZ on rock mass behavior is important for the long term stability, economy, and safety points of view. In the case of underground repository, which requires high level safety criteria, the accurate prediction of the long and short term mechanical, hydraulic, and thermal behaviors is especially important. In this study, the size and characteristics of EDZ developed during the construction of the KAERI underground research tunnel, which was constructed by controlled blasting, were investigated using various methods. Goodman jack test for measuring deformation modulus, Georadar, rock core observation, MPBX, and stressmeter were carried out at KURT. The rock cores from the boreholes were tested in laboratory for estimating the EDZ size. Empirical and theoretical equations were also used for the prediction of EDZ. The results from laboratory and in situ tests were used in three-dimensional hydro-mechanical and thermo-mechanical analysis for the evaluation of the EDZ effect. The understanding of EDZ size and the property changes in EDZ from in situ and laboratory tests will be used for the planning, design, and analysis of in situ experiments in KURT. The results from the EDZ study will be helpful for the system design as well as safety analysis of a radioactive repository.

  6. Recognition tunneling

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  7. Recognition tunneling

    Energy Technology Data Exchange (ETDEWEB)

    Lindsay, Stuart; He Jin; Zhang Peiming; Chang Shuai; Huang Shuo [Biodesign Institute, Arizona State University, Tempe, AZ 85287 (United States); Sankey, Otto [Department of Physics, Arizona State University, Tempe, AZ 85287 (United States); Hapala, Prokop; Jelinek, Pavel [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 1862 53, Prague (Czech Republic)

    2010-07-02

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

  8. The Design and Capabilities of the EXIST Optical and Infra-Red Telescope (IRT)

    Science.gov (United States)

    Kutyrev, A S.; Moseley, S. H.; Golisano, C.; Gong, Q.; Allen, B. T.; Gehrels, N.; Grindlay, J. E.; Hong, J. S.; Woodgate, B. E.

    2010-01-01

    The Infra-Red Telescope is a critical element of the EXIST (Energetic X-Ray Imaging Survey Telescope) observatory. The primary goal of the IRT is to obtain photometric and spectroscopic measurements of high redshift (> or =6) gamma ray reaching to the epoque of reionization. The photometric and spectral capabilities of the IRT will allow to use GRB afterglow as probes of the composition and ionization state of the intergalactic medium of the young universe. A prompt follow up (within three minutes) of the transient discovered by the EXIST makes IRT a unique tool for detection and study of these events in the infrared and optical wavelength, which is particularly valuable at wavelengths unavailable to the ground based observatories. We present the results of the mission study development on the IRT as part of the EXIST observatory. Keywords: infrared spectroscopy, space telescope, gamma ray bursts, early universe

  9. A new network of faint calibration stars from the near infrared spectrometer (NIRS) on the IRTS

    Science.gov (United States)

    Freund, Minoru M.; Matsuura, Mikako; Murakami, Hiroshi; Cohen, Martin; Noda, Manabu; Matsuura, Shuji; Matsumoto, Toshio

    1997-01-01

    The point source extraction and calibration of the near infrared spectrometer (NIRS) onboard the Infrared Telescope in Space (IRTS) is described. About 7 percent of the sky was observed during a one month mission in the range of 1.4 micrometers to 4 micrometers. The accuracy of the spectral shape and absolute values of calibration stars provided by the NIRS/IRTS were validated.

  10. WIND TUNNEL RESEARCH ON THE INFLUENCE OF ACTIVE AIRFLOW ON THE LIFT FORCE GENERATED BY THE AIRFOIL

    Directory of Open Access Journals (Sweden)

    Paweł Magryta

    2013-09-01

    Full Text Available The paper discusses the results of wind tunnel tests of airfoils with additional active airflow applied to their upper surfaces. These studies were carried out for a range of velocities up to 28 m/s in an open wind tunnel. Several types of airfoils selected for the examination feature different geometries and are widely applied in today’s aviation industry. The changes in the lift and drag force generated by these airfoils were recorded during the study. The test bench for the tests was equipped with a compressor and a vacuum pump to enable airflow through some holes on the airfoil upper surface. A rapid prototyping method and a 3D printer based on a powder printing technique were applied to print the airfoils. All of their surfaces were subject to surface grinding to smooth their external surfaces. The wind tunnel tests with and without active airflow applied to airfoils are summarised in the paper.

  11. Ground penetrating radar for fracture mapping in underground hazardous waste disposal sites: A case study from an underground research tunnel, South Korea

    Science.gov (United States)

    Baek, Seung-Ho; Kim, Seung-Sep; Kwon, Jang-Soon; Um, Evan Schankee

    2017-06-01

    Secure disposal or storage of nuclear waste within stable geologic environments hinges on the effectiveness of artificial and natural radiation barriers. Fractures in the bedrock are viewed as the most likely passage for the transport of radioactive waste away from a disposal site. We utilize ground penetrating radar (GPR) to map fractures in the tunnel walls of an underground research tunnel at the Korea Atomic Energy Research Institute (KAERI). GPR experiments within the KAERI Underground Research Tunnel (KURT) were carried out by using 200 MHz, 500 MHz, and 1000 MHz antennas. By using the high-frequency antennas, we were able to identify small-scale fractures, which were previously unidentified during the tunnel excavation process. Then, through 3-D visualization of the grid survey data, we reconstructed the spatial distribution and interconnectivity of the multi-scale fractures within the wall. We found that a multi-frequency GPR approach provided more details of the complex fracture network, including deep structures. Furthermore, temporal changes in reflection polarity between the GPR surveys enabled us to infer the hydraulic characteristics of the discrete fracture network developed behind the surveyed wall. We hypothesized that the fractures exhibiting polarity change may be due to a combination of air-filled and mineralogical boundaries. Simulated GPR scans for the considered case were consistent with the observed GPR data. If our assumption is correct, the groundwater flow into these near-surface fractures may form the water-filled fractures along the existing air-filled ones and hence cause the changes in reflection polarity over the given time interval (i.e., 7 days). Our results show that the GPR survey is an efficient tool to determine fractures at various scales. Time-lapse GPR data may be essential to characterize the hydraulic behavior of discrete fracture networks in underground disposal facilities.

  12. Possible safety hazards associated with the operation of the 0.3-m transonic cryogenic tunnel at the NASA Langley Research Center

    Science.gov (United States)

    Webster, T. J.

    1982-01-01

    The 0.3 m Transonic Cryogenic Tunnel (TCT) at the NASA Langley Research Center was built in 1973 as a facility intended to be used for no more than 60 hours in order to verify the validity of the cryogenic wind tunnel concept at transonic speeds. The role of the 0.3 m TCT has gradually changed until now, after over 3000 hours of operation, it is classified as a major NASA research facility and, under the administration of the Experimental Techniques Branch, it is used extensively for the testing of airfoils at high Reynolds numbers and for the development of various technologies related to the efficient operation and use of cryogenic wind tunnels. The purpose of this report is to document the results of a recent safety analysis of the 0.3 m TCT facility. This analysis was made as part of an on going program with the Experimental Techniques Branch designed to ensure that the existing equipment and current operating procedures of the 0.3 m TCT facility are acceptable in terms of today's standards of safety for cryogenic systems.

  13. Modeling the hydraulic characteristics of a fractured rock mass with correlated fracture length and aperture: Application in the underground research tunnel at KAERI

    International Nuclear Information System (INIS)

    Bang, Sang Hyuk; Jeon, Seok Won; Kwon, Sang Ki

    2012-01-01

    A three-dimensional discrete fracture network model was developed in order to simulate the hydraulic characteristics of a granitic rock mass at Korea Atomic Energy Research Institute (KAERI) Underground Research Tunnel (KURT). The model N used a three-dimensional discrete fracture network (DFN), assuming a correlation between the length and aperture of the fractures, and a trapezoid flow path in the fractures. These assumptions that previous studies have not considered could make the developed model more practical and reasonable. The geologic and hydraulic data of the fractures were obtained in the rock mass at the KURT. Then, these data were applied to the developed fracture discrete network model. The model was applied in estimating the representative elementary volume (REV), the equivalent hydraulic conductivity tensors, and the amount of groundwater inflow into the tunnel. The developed discrete fracture network model can determine the REV size for the rock mass with respect to the hydraulic behavior and estimate the groundwater flow into the tunnel at the KURT. Therefore, the assumptions that the fracture length is correlated to the fracture aperture and the flow in a fracture occurs in a trapezoid shape appear to be effective in the DFN analysis used to estimate the hydraulic behavior of the fractured rock mass.

  14. 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.

  15. Tunnelling Effects in Chemistry

    Indian Academy of Sciences (India)

    IAS Admin

    GENERAL ⎜ ARTICLE. Tunnelling Effects in Chemistry. Molecules in the Strange Quantum World. Sharmistha Karmakar, Deepthi Jose and Ayan Datta. (left) Sharmistha Karmakar is doing her PhD in the group of. Ayan Datta, IACS,. Kolkata. Her research interests are modelling molecules with strong optical absorbtion and.

  16. Outcome of the geological mapping of the ONKALO underground research facility access tunnel, chainage 990-1980

    International Nuclear Information System (INIS)

    Nordbaeck, N.; Engstroem, J.

    2010-06-01

    This report describes the lithology and geological structures of the ONKALO underground rock characterization facility access tunnel in chainage 990-1980. This part of the tunnel was excavated and mapped from spring 2006 to spring 2007. The bedrock is very heterogenic and mainly composed of veined gneiss and diatexitic gneiss but many dykes and sections of pegmatitic granite also occur. In addition, small sections of stromatic gneiss and K-feldspar porphyry are present. There are also numerous inclusions of mica gneiss, quartz gneiss and skarn. The foliation dips moderately towards SE. 22 fold axes and 22 axial planes were measured from the ONKALO tunnel in chainage 990-1980 and all except one have been interpreted to belong to deformation phase D3. The measured fold axes have various orientations, but most have moderate plunges and ENE or WSW-trending ones dominate. The axial planes typically plunge moderately towards SE. A total of 10355 fractures were measured. Three main fracture sets were distinguished from the measured orientations: set 1 fractures are more or less horizontal, set 2 fractures are vertical and trend approximately ENE-WSW. The set 3 fractures are vertical and NWN-SES trending. Among the longer fractures (1 m and over in length) also a fourth set was observed. The set 4 fractures are, parallel to the foliation, NE-SW trending and moderately dipping. From the measured fractures, 395 were slickensided. The slickensided fractures are mainly either vertical N-S trending (set 3) or parallel to the foliation, trending NE-SW with moderate dip to SE. Measurements from slickenside surfaces show lineations plunging mainly to N or E with shallow dip. Sense of movement for the slickenside surfaces varies. The chainage 990-1980 contains 127 tunnel-crosscutting fractures with mostly vertical, N-S trending (set 3) or subhorizontal (set 1) orientation. The most common filling minerals are calcite, pyrite, chlorite, kaolinite, chlorite, epidote and muscovite

  17. plink: An R Package for Linking Mixed-Format Tests Using IRT-Based Methods

    Directory of Open Access Journals (Sweden)

    Jonathan P. Weeks

    2010-10-01

    Full Text Available The R package plink has been developed to facilitate the linking of mixed-format tests for multiple groups under a common item design using unidimensional and multidimensional IRT-based methods. This paper presents the capabilities of the package in the context of the unidimensional methods. The package supports nine unidimensional item response models (the Rasch model, 1PL, 2PL, 3PL, graded response model, partial credit and generalized partial credit model, nominal response model, and multiple-choice model and four separate calibration linking methods (mean/sigma, mean/mean, Haebara, and Stocking-Lord. It also includes functions for importing item and/or ability parameters from common IRT software, conducting IRT true-score and observed-score equating, and plotting item response curves and parameter comparison plots.

  18. 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 ...

  19. Polytomous IRT models and monotone likelihood ratio of the total score

    NARCIS (Netherlands)

    Hemker, BT; Sijtsma, Klaas; Molenaar, Ivo W; Junker, BW

    1996-01-01

    In a broad class of item response theory (IRT) models for dichotomous items the unweighted total score has monotone likelihood ratio (MLR) in the latent trait theta. In this study, it is shown that for polytomous items MLR holds for the partial credit model and a trivial generalization of this

  20. Using a Linear Regression Method to Detect Outliers in IRT Common Item Equating

    Science.gov (United States)

    He, Yong; Cui, Zhongmin; Fang, Yu; Chen, Hanwei

    2013-01-01

    Common test items play an important role in equating alternate test forms under the common item nonequivalent groups design. When the item response theory (IRT) method is applied in equating, inconsistent item parameter estimates among common items can lead to large bias in equated scores. It is prudent to evaluate inconsistency in parameter…

  1. The Robustness of IRT-Based Vertical Scaling Methods to Violation of Unidimensionality

    Science.gov (United States)

    Yin, Liqun

    2013-01-01

    In recent years, many states have adopted Item Response Theory (IRT) based vertically scaled tests due to their compelling features in a growth-based accountability context. However, selection of a practical and effective calibration/scaling method and proper understanding of issues with possible multidimensionality in the test data is critical to…

  2. An Extension of IRT-Based Equating to the Dichotomous Testlet Response Theory Model

    Science.gov (United States)

    Tao, Wei; Cao, Yi

    2016-01-01

    Current procedures for equating number-correct scores using traditional item response theory (IRT) methods assume local independence. However, when tests are constructed using testlets, one concern is the violation of the local item independence assumption. The testlet response theory (TRT) model is one way to accommodate local item dependence.…

  3. Adaptive mastery testing using a multidimensional IRT model and Bayesian sequential decision theory

    NARCIS (Netherlands)

    Glas, Cornelis A.W.; Vos, Hendrik J.

    2000-01-01

    This paper focuses on a version of sequential mastery testing (i.e., classifying students as a master/nonmaster or continuing testing and administering another item or testlet) in which response behavior is modeled by a multidimensional item response theory (IRT) model. First, a general theoretical

  4. A Unified Nonparametric IRT Model for "d"-Dimensional Psychological Test Data ("d"-Isop)

    Science.gov (United States)

    Scheiblechner, Hartmann

    2007-01-01

    The (univariate) isotonic psychometric (ISOP) model (Scheiblechner, 1995) is a nonparametric IRT model for dichotomous and polytomous (rating scale) psychological test data. A weak subject independence axiom W1 postulates that the subjects are ordered in the same way except for ties (i.e., similarly or isotonically) by all items of a psychological…

  5. The construction of parallel tests from IRT-based item banks

    NARCIS (Netherlands)

    Boekkooi-Timminga, Ellen

    1989-01-01

    The construction of parallel tests from item response theory (IRT) based item banks is discussed. Tests are considered parallel whenever their information functions are identical. After the methods for constructing parallel tests are considered, the computational complexity of 0-1 linear programming

  6. Detecting DIF in Polytomous Items Using MACS, IRT and Ordinal Logistic Regression

    Science.gov (United States)

    Elosua, Paula; Wells, Craig

    2013-01-01

    The purpose of the present study was to compare the Type I error rate and power of two model-based procedures, the mean and covariance structure model (MACS) and the item response theory (IRT), and an observed-score based procedure, ordinal logistic regression, for detecting differential item functioning (DIF) in polytomous items. A simulation…

  7. Comparison of IRT Likelihood Ratio Test and Logistic Regression DIF Detection Procedures

    Science.gov (United States)

    Atar, Burcu; Kamata, Akihito

    2011-01-01

    The Type I error rates and the power of IRT likelihood ratio test and cumulative logit ordinal logistic regression procedures in detecting differential item functioning (DIF) for polytomously scored items were investigated in this Monte Carlo simulation study. For this purpose, 54 simulation conditions (combinations of 3 sample sizes, 2 sample…

  8. An Empirical Investigation of Thurstone and IRT Methods of Scaling Achievement Tests.

    Science.gov (United States)

    Becker, Douglas F.; Forsyth, Robert A.

    1992-01-01

    Measurement scales developed using Thurstone and item-response theory (IRT) methods of scaling achievement tests for the same single-level data were compared for approximately 4,000 high school students taking the Iowa Tests of Educational Development in 1975. Results of both approaches indicate that variability increases as grade level increases.…

  9. Comparing Three Estimation Methods for the Three-Parameter Logistic IRT Model

    Science.gov (United States)

    Lamsal, Sunil

    2015-01-01

    Different estimation procedures have been developed for the unidimensional three-parameter item response theory (IRT) model. These techniques include the marginal maximum likelihood estimation, the fully Bayesian estimation using Markov chain Monte Carlo simulation techniques, and the Metropolis-Hastings Robbin-Monro estimation. With each…

  10. Conscientiousness in the workplace : Applying mixture IRT to investigate scalability and predictive validity

    NARCIS (Netherlands)

    Egberink, I.J.L.; Meijer, R.R.; Veldkamp, B.P.

    Mixture item response theory (IRT) models have been used to assess multidimensionality of the construct being measured and to detect different response styles for different groups. In this study a mixture version of the graded response model was applied to investigate scalability and predictive

  11. Multi-level IRT with measurement error in the predictor variables

    NARCIS (Netherlands)

    Fox, Gerardus J.A.; Glas, Cornelis A.W.

    1998-01-01

    A two-level regression model is imposed on the ability parameters in an item response theory (IRT) model. The advantage of using latent rather than observed scores as dependent variables of a multilevel model is that this offers the possibility of separating the influence of item difficulty and

  12. Stochastic EM for estimating the parameters of a multilevel IRT model

    NARCIS (Netherlands)

    Fox, Gerardus J.A.

    2003-01-01

    An item response theory (IRT) model is used as a measurement error model for the dependent variable of a multilevel model. The dependent variable is latent but can be measured indirectly by using tests or questionnaires. The advantage of using latent scores as dependent variables of a multilevel

  13. Detecting Intervention Effects Using a Multilevel Latent Transition Analysis with a Mixture IRT Model

    Science.gov (United States)

    Cho, Sun-Joo; Cohen, Allan S.; Bottge, Brian

    2013-01-01

    A multilevel latent transition analysis (LTA) with a mixture IRT measurement model (MixIRTM) is described for investigating the effectiveness of an intervention. The addition of a MixIRTM to the multilevel LTA permits consideration of both potential heterogeneity in students' response to instructional intervention as well as a methodology for…

  14. Stochastic EM for estimating the parameters of a multilevel IRT model

    NARCIS (Netherlands)

    Fox, Gerardus J.A.

    2000-01-01

    An item response theory (IRT) model is used as a measurement error model for the dependent variable of a multilevel model where tests or questionnaires consisting of separate items are used to perform a measurement error analysis. The advantage of using latent scores as dependent variables of a

  15. Assessing the Item Response Theory with Covariate (IRT-C) Procedure for Ascertaining Differential Item Functioning

    Science.gov (United States)

    Tay, Louis; Vermunt, Jeroen K.; Wang, Chun

    2013-01-01

    We evaluate the item response theory with covariates (IRT-C) procedure for assessing differential item functioning (DIF) without preknowledge of anchor items (Tay, Newman, & Vermunt, 2011). This procedure begins with a fully constrained baseline model, and candidate items are tested for uniform and/or nonuniform DIF using the Wald statistic.…

  16. Standard Error Estimation of 3PL IRT True Score Equating with an MCMC Method

    Science.gov (United States)

    Liu, Yuming; Schulz, E. Matthew; Yu, Lei

    2008-01-01

    A Markov chain Monte Carlo (MCMC) method and a bootstrap method were compared in the estimation of standard errors of item response theory (IRT) true score equating. Three test form relationships were examined: parallel, tau-equivalent, and congeneric. Data were simulated based on Reading Comprehension and Vocabulary tests of the Iowa Tests of…

  17. Real time computer data system for the 40 x 80 ft wind tunnel facility at Ames Research Center

    Science.gov (United States)

    Cambra, J. M.; Tolari, G. P.

    1974-01-01

    The wind tunnel realtime computer system is a distributed data gathering system that features a master computer subsystem, a high speed data gathering subsystem, a quick look dynamic analysis and vibration control subsystem, an analog recording back-up subsystem, a pulse code modulation (PCM) on-board subsystem, a communications subsystem, and a transducer excitation and calibration subsystem. The subsystems are married to the master computer through an executive software system and standard hardware and FORTRAN software interfaces. The executive software system has four basic software routines. These are the playback, setup, record, and monitor routines. The standard hardware interfaces along with the software interfaces provide the system with the capability of adapting to new environments.

  18. Equipment concept design and development plans for microgravity science and applications research on space station: Combustion tunnel, laser diagnostic system, advanced modular furnace, integrated electronics laboratory

    Science.gov (United States)

    Uhran, M. L.; Youngblood, W. W.; Georgekutty, T.; Fiske, M. R.; Wear, W. O.

    1986-01-01

    Taking advantage of the microgravity environment of space NASA has initiated the preliminary design of a permanently manned space station that will support technological advances in process science and stimulate the development of new and improved materials having applications across the commercial spectrum. Previous studies have been performed to define from the researcher's perspective, the requirements for laboratory equipment to accommodate microgravity experiments on the space station. Functional requirements for the identified experimental apparatus and support equipment were determined. From these hardware requirements, several items were selected for concept designs and subsequent formulation of development plans. This report documents the concept designs and development plans for two items of experiment apparatus - the Combustion Tunnel and the Advanced Modular Furnace, and two items of support equipment the Laser Diagnostic System and the Integrated Electronics Laboratory. For each concept design, key technology developments were identified that are required to enable or enhance the development of the respective hardware.

  19. Final Scientific/Technical Report: Electronics for Large Superconducting Tunnel Junction Detector Arrays for Synchrotron Soft X-ray Research

    Energy Technology Data Exchange (ETDEWEB)

    Warburton, William K

    2009-03-06

    Superconducting tunnel junction (STJ) detectors offer a an approach to detecting soft x-rays with energy resolutions 4-5 times better and at rates 10 faster than traditions semiconductor detectors. To make such detectors feasible, however, then need to be deployed in large arrays of order 1000 detectors, which in turn implies that their processing electronics must be compact, fully computer controlled, and low cost per channel while still delivering ultra-low noise performance so as to not degrade the STJ's performance. We report on our progress in designing a compact, low cost preamplifier intended for this application. In particular, we were able to produce a prototype preamplifier of 2 sq-cm area and a parts cost of less than $30 that matched the energy resolution of the best conventional system to date and demonstrated its ability to acquire an STJ I-V curve under computer control, the critical step for determining and setting the detectors' operating points under software control.

  20. Palladium electrodes for molecular tunnel junctions

    International Nuclear Information System (INIS)

    Chang Shuai; Sen Suman; Zhang Peiming; Gyarfas, Brett; Ashcroft, Brian; Lindsay, Stuart; Lefkowitz, Steven; Peng Hongbo

    2012-01-01

    Gold has been the metal of choice for research on molecular tunneling junctions, but it is incompatible with complementary metal–oxide–semiconductor fabrication because it forms deep level traps in silicon. Palladium electrodes do not contaminate silicon, and also give higher tunnel current signals in the molecular tunnel junctions that we have studied. The result is cleaner signals in a recognition-tunneling junction that recognizes the four natural DNA bases as well as 5-methyl cytosine, with no spurious background signals. More than 75% of all the recorded signal peaks indicate the base correctly. (paper)

  1. Quantifying 'problematic' DIF within an IRT framework: application to a cancer stigma index.

    Science.gov (United States)

    Edelen, Maria Orlando; Stucky, Brian D; Chandra, Anita

    2015-01-01

    DIF detection within an IRT framework is highly powerful, often identifying significant DIF that is of little clinical importance. This paper introduces two metrics for IRT DIF evaluation that can discern potentially problematic DIF among items flagged with statistically significant DIF. Computation of two DIF metrics-(1) a weighted area between the expected score curves (wABC) and (2) a difference in expected a posteriori scores across item response categories (dEAP)-is described. Their use is demonstrated using data from a 27-item cancer stigma index fielded to four adult samples: (1) Arabic (N = 633) and (2) English speakers (N = 324) residing in Jordan and Egypt, and (3) English (N = 500) and (4) Mandarin speakers (N = 500) residing in China. We used IRTPRO's DIF module to calculate IRT-based Wald chi-square DIF statistics according to language within each region. After standard p value adjustments for multiple comparisons, we further evaluated DIF impact with wABC and dEAP. There were a total of twenty statistically significant DIF comparisons after p value adjustment. The wABCs for these items ranged from 0.13 to 0.90. Upon inspection of curves, DIF comparisons with wABCs >0.3 were deemed potentially problematic and were considered further for removal. The dEAP metric was also informative regarding impact of DIF on expected scores, but less consistently useful for narrowing down potentially problematic items. The calculations of wABC and dEAP function as DIF effect size indicators. Use of these metrics can substantially augment IRT DIF evaluation by discerning truly problematic DIF items among those with statistically significant DIF.

  2. 7 x 10 Foot Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — This wind tunnel is used for basic and applied research in aeromechanics on advanced and unique technology rotorcraft. It supports research on advanced concepts and...

  3. A generalized longitudinal mixture IRT model for measuring differential growth in learning environments.

    Science.gov (United States)

    Kadengye, Damazo T; Ceulemans, Eva; Van den Noortgate, Wim

    2014-09-01

    This article describes a generalized longitudinal mixture item response theory (IRT) model that allows for detecting latent group differences in item response data obtained from electronic learning (e-learning) environments or other learning environments that result in large numbers of items. The described model can be viewed as a combination of a longitudinal Rasch model, a mixture Rasch model, and a random-item IRT model, and it includes some features of the explanatory IRT modeling framework. The model assumes the possible presence of latent classes in item response patterns, due to initial person-level differences before learning takes place, to latent class-specific learning trajectories, or to a combination of both. Moreover, it allows for differential item functioning over the classes. A Bayesian model estimation procedure is described, and the results of a simulation study are presented that indicate that the parameters are recovered well, particularly for conditions with large item sample sizes. The model is also illustrated with an empirical sample data set from a Web-based e-learning environment.

  4. A Supermagnetic Tunnel Full of Subatomic Action

    CERN Multimedia

    2008-01-01

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

  5. Transport of dangerous goods through road tunnels

    DEFF Research Database (Denmark)

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

    1999-01-01

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

  6. Submucosal tunneling techniques: current perspectives

    Directory of Open Access Journals (Sweden)

    Kobara H

    2014-04-01

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

  7. Hypersonic Tunnel Facility (HTF)

    Data.gov (United States)

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

  8. Quantum theory of tunneling

    CERN Document Server

    Razavy, Mohsen

    2014-01-01

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

  9. Road and Railroad Tunnels

    Data.gov (United States)

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

  10. Transonic Dynamics Tunnel (TDT)

    Data.gov (United States)

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

  11. Major SSC tunneling begins

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    In Texas, work has been completed on the first on the Superconducting Supercollider's major shafts. Now a boring machine has started driving the fifty-four mile elliptical accelerator tunnel. To date, contracts let for the tunnel have come in far below preliminary estimates. Five of the main fourteen foot diameter tunnel contracts have been awarded for a total of 107.4 million dollars, about forty million dollars below estimates. These contracts represent %60 percent of the total tunneling project

  12. Overexpression of ZmIRT1 and ZmZIP3 Enhances Iron and Zinc Accumulation in Transgenic Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Suzhen Li

    Full Text Available Iron and zinc are important micronutrients for both the growth and nutrient availability of crop plants, and their absorption is tightly controlled by a metal uptake system. Zinc-regulated transporters, iron-regulated transporter-like proteins (ZIP, is considered an essential metal transporter for the acquisition of Fe and Zn in graminaceous plants. Several ZIPs have been identified in maize, although their physiological function remains unclear. In this report, ZmIRT1 was shown to be specifically expressed in silk and embryo, whereas ZmZIP3 was a leaf-specific gene. Both ZmIRT1 and ZmZIP3 were shown to be localized to the plasma membrane and endoplasmic reticulum. In addition, transgenic Arabidopsis plants overexpressing ZmIRT1 or ZmZIP3 were generated, and the metal contents in various tissues of transgenic and wild-type plants were examined based on ICP-OES and Zinpyr-1 staining. The Fe and Zn concentration increased in roots and seeds of ZmIRT1-overexpressing plants, while the Fe content in shoots decreased. Overexpressing ZmZIP3 enhanced Zn accumulation in the roots of transgenic plants, while that in shoots was repressed. In addition, the transgenic plants showed altered tolerance to various Fe and Zn conditions compared with wild-type plants. Furthermore, the genes associated with metal uptake were stimulated in ZmIRT1 transgenic plants, while those involved in intra- and inter- cellular translocation were suppressed. In conclusion, ZmIRT1 and ZmZIP3 are functional metal transporters with different ion selectivities. Ectopic overexpression of ZmIRT1 may stimulate endogenous Fe uptake mechanisms, which may facilitate metal uptake and homeostasis. Our results increase our understanding of the functions of ZIP family transporters in maize.

  13. Gibberellic acid alleviates cadmium toxicity by reducing nitric oxide accumulation and expression of IRT1 in Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Zhu, Xiao Fang; Jiang, Tao; Wang, Zhi Wei; Lei, Gui Jie; Shi, Yuan Zhi; Li, Gui Xin; Zheng, Shao Jian

    2012-01-01

    Highlights: ► Cd reduces endogenous GA levels in Arabidopsis. ► GA exogenous applied decreases Cd accumulation in plant. ► GA suppresses the Cd-induced accumulation of NO. ► Decreased NO level downregulates the expression of IRT1. ► Suppressed IRT1 expression reduces Cd transport across plasma membrane. - Abstract: Gibberellic acid (GA) is involved in not only plant growth and development but also plant responses to abiotic stresses. Here it was found that treating the plants with GA concentrations from 0.1 to 5 μM for 24 h had no obvious effect on root elongation in the absence of cadmium (Cd), whereas in the presence of Cd 2+ , GA at 5 μM improved root growth, reduced Cd content and lipid peroxidation in the roots, indicating that GA can partially alleviate Cd toxicity. Cd 2+ increased nitric oxide (NO) accumulation in the roots, but GA remarkably reduced it, and suppressed the up-regulation of the expression of IRT1. In contrary, the beneficial effect of GA on alleviating Cd toxicity was not observed in an IRT1 knock-out mutant irt1, suggesting the involvement of IRT1 in Cd 2+ absorption. Furthermore, the GA-induced reduction of NO and Cd content can also be partially reversed by the application of a NO donor (S-nitrosoglutathione [GSNO]). Taken all these together, the results showed that GA-alleviated Cd toxicity is mediated through the reduction of the Cd-dependent NO accumulation and expression of Cd 2+ uptake related gene-IRT1 in Arabidopsis.

  14. DNS Tunneling Detection Method Based on Multilabel Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Ahmed Almusawi

    2018-01-01

    Full Text Available DNS tunneling is a method used by malicious users who intend to bypass the firewall to send or receive commands and data. This has a significant impact on revealing or releasing classified information. Several researchers have examined the use of machine learning in terms of detecting DNS tunneling. However, these studies have treated the problem of DNS tunneling as a binary classification where the class label is either legitimate or tunnel. In fact, there are different types of DNS tunneling such as FTP-DNS tunneling, HTTP-DNS tunneling, HTTPS-DNS tunneling, and POP3-DNS tunneling. Therefore, there is a vital demand to not only detect the DNS tunneling but rather classify such tunnel. This study aims to propose a multilabel support vector machine in order to detect and classify the DNS tunneling. The proposed method has been evaluated using a benchmark dataset that contains numerous DNS queries and is compared with a multilabel Bayesian classifier based on the number of corrected classified DNS tunneling instances. Experimental results demonstrate the efficacy of the proposed SVM classification method by obtaining an f-measure of 0.80.

  15. A Hierarchical Multi-Unidimensional IRT Approach for Analyzing Sparse, Multi-Group Data for Integrative Data Analysis.

    Science.gov (United States)

    Huo, Yan; de la Torre, Jimmy; Mun, Eun-Young; Kim, Su-Young; Ray, Anne E; Jiao, Yang; White, Helene R

    2015-09-01

    The present paper proposes a hierarchical, multi-unidimensional two-parameter logistic item response theory (2PL-MUIRT) model extended for a large number of groups. The proposed model was motivated by a large-scale integrative data analysis (IDA) study which combined data (N = 24,336) from 24 independent alcohol intervention studies. IDA projects face unique challenges that are different from those encountered in individual studies, such as the need to establish a common scoring metric across studies and to handle missingness in the pooled data. To address these challenges, we developed a Markov chain Monte Carlo (MCMC) algorithm for a hierarchical 2PL-MUIRT model for multiple groups in which not only were the item parameters and latent traits estimated, but the means and covariance structures for multiple dimensions were also estimated across different groups. Compared to a few existing MCMC algorithms for multidimensional IRT models that constrain the item parameters to facilitate estimation of the covariance matrix, we adapted an MCMC algorithm so that we could directly estimate the correlation matrix for the anchor group without any constraints on the item parameters. The feasibility of the MCMC algorithm and the validity of the basic calibration procedure were examined using a simulation study. Results showed that model parameters could be adequately recovered, and estimated latent trait scores closely approximated true latent trait scores. The algorithm was then applied to analyze real data (69 items across 20 studies for 22,608 participants). The posterior predictive model check showed that the model fit all items well, and the correlations between the MCMC scores and original scores were overall quite high. An additional simulation study demonstrated robustness of the MCMC procedures in the context of the high proportion of missingness in data. The Bayesian hierarchical IRT model using the MCMC algorithms developed in the current study has the potential to

  16. Experimental evaluation of two turning vane designs for fan drive corner of 0.1-scale model of NASA Lewis Research Center's proposed altitude wind tunnel

    Science.gov (United States)

    Boldman, Donald R.; Moore, Royce D.; Shyne, Rickey J.

    1987-01-01

    Two turning vane designs were experimentally evaluated for corner 2 of a 0.1 scale model of the NASA Lewis Research Center's proposed Altitude Wind Tunnel (AWT). Corner 2 contained a simulated shaft fairing for a fan drive system to be located downstream of the corner. The corner was tested with a bellmouth inlet followed by a 0.1 scale model of the crossleg diffuser designed to connect corners 1 and 2 of the AWT. Vane A was a controlled-diffusion airfoil shape; vane B was a circular-arc airfoil shape. The A vanes were tested in several arrangements which included the resetting of the vane angle by -5 degrees or the removal of the outer vane. The lowest total pressure loss for vane A configuration was obtained at the negative reset angle. The loss coefficient increased slightly with the Mach number, ranging from 0.165 to 0.175 with a loss coefficient of 0.170 at the inlet design Mach number of 0.24. Removal of the outer vane did not alter the loss. Vane B loss coefficients were essentially the same as those for the reset vane A configurations. The crossleg diffuser loss coefficient was 0.018 at the inlet design Mach number of 0.33.

  17. A Mixture IRT Analysis of Risky Youth Behavior

    Directory of Open Access Journals (Sweden)

    Holmes eFinch

    2011-05-01

    Full Text Available The study reported in this manuscript used a mixture item response model with data from the Youth Risk Behavior Survey 2009 (N = 16,410 to identify subtypes of adolescents at-risk for engaging in unhealthy behaviors, and to find individual survey items that were most effective at identifying such students within each subtype. The goal of the manuscript is twofold: 1 To demonstrate the utility of the mixture item response theory model for identifying subgroups in the population and for highlighting the use of group specific item response parameters and 2 To identify typologies of adolescents based on their propensity for engaging in sexually and substance use risky behaviors. Results indicate that 4 classes of youth exist in the population, with differences in risky sexual behaviors and substance use. The first group had a greater propensity to engage in risky sexual behavior, while group 2 was more likely to smoke tobacco and drink alcohol. Group 3 was the most likely to use other substances, such as marijuana, methamphetamine, and other mind altering drugs, and group 4 had the lowest propensity for engaging in any of the sexual or substance use behaviors included in the survey. Finally, individual items were identified for each group that can be most effective at identifying individuals at greatest risk. Further proposed directions of research and the contribution of this analysis to the existing literature are discussed.

  18. Spin-dependent tunnelling in magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Tsymbal, Evgeny Y; Mryasov, Oleg N; LeClair, Patrick R

    2003-01-01

    The phenomenon of electron tunnelling has been known since the advent of quantum mechanics, but continues to enrich our understanding of many fields of physics, as well as creating sub-fields on its own. Spin-dependent tunnelling (SDT) in magnetic tunnel junctions (MTJs) has recently aroused enormous interest and has developed in a vigorous field of research. The large tunnelling magnetoresistance (TMR) observed in MTJs garnered much attention due to possible applications in non-volatile random-access memories and next-generation magnetic field sensors. This led to a number of fundamental questions regarding the phenomenon of SDT. In this review article we present an overview of this field of research. We discuss various factors that control the spin polarization and magnetoresistance in MTJs. Starting from early experiments on SDT and their interpretation, we consider thereafter recent experiments and models which highlight the role of the electronic structure of the ferromagnets, the insulating layer, and the ferromagnet/insulator interfaces. We also discuss the role of disorder in the barrier and in the ferromagnetic electrodes and their influence on TMR. (topical review)

  19. The local reliability of the 15-item version of the Geriatric Depression Scale: An item response theory (IRT) study.

    Science.gov (United States)

    Chiesi, Francesca; Primi, Caterina; Pigliautile, Martina; Ercolani, Sara; Della Staffa, Manuela Conestabile; Longo, Annalisa; Boccardi, Virginia; Mecocci, Patrizia

    2017-05-01

    The 15-item version of the Geriatric Depression Scale (GDS-15) is a self-report screening instrument widely used. The current study aimed at providing evidence of the measurement precision of the GDS-15 applying Item Response Theory (IRT). The relative contribution of each item and the reliability of the whole scale in measuring the trait level around the cutoffs were investigated employing data collected from a sample consisting of 1344 old people (M=76.44years, SD=5.13; 58.7% women) involved in a large gerontological research project. The unidimensional two-parameter (2PL) logistic model was employed to item estimate location and slope parameters as well as the Test Information Function (TIF). Nine out of fifteen items were located around the cutoffs and the slopes showed that the majority of the items had substantial discrimination ability. The TIF peaked in correspondence of the cutoffs attesting the good local reliability of the scale. These findings support to the utility of the GDS-15 in detecting depression among older people. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. A novel technique for the measurement of plasma displacement in IR-T1 tokamak

    International Nuclear Information System (INIS)

    Salar Elahi, A.; Ghoranneviss, M.

    2010-01-01

    In this paper we present a novel technique based on poloidal magnetic flux for determination of plasma displacement in IR-T1 tokamak. This instrument consists of a two semicircle wires which installed toroidally on inner and outer sides of tokamak chamber and connected with each other. In order to receive the poloidal flux on Last Closed Flux Surface (LCFS); this instrument installed on polar coordinate so as projection of it on midplane lie on LCFS. Really, this instrument receives the difference between poloidal flux on inner and outer sides of LCFS, which we needed in calculating of the Shafranov shift. Main benefits of our proposed instrument are that it is a simple, solid, and also its output is directly related to the Shafranov shift. Based on this technique we determined the plasma position and to compare the result obtained using this method, multipole moments method is also experimented on IR-T1. Results of the two techniques are in good agreement with each other.

  1. Inspection of radiant heating floor applying non-destructive testing techniques: GPR and IRT

    Directory of Open Access Journals (Sweden)

    Susana Lagüela-López

    2015-01-01

    Full Text Available La inspección de suelos radiantes requiere el uso de técnicas no destructivas, tratando de minimizar el impacto de la inspección, así como el tiempo y el coste, además de maximizar la información adquirida de cara al mejor diagnóstico posible. Con este objetivo, la aplicación de termografía infrarroja (IRT y georradar (GPR se propone para la inspección de suelos radiantes con cobertura de diferentes materiales, para evaluar las capacidades y la información adquirible con cada técnica. Los resultados muestran que cada técnica proporciona diferentes tipos de información: estado de las tuberías (IRT, geometría y configuración (GPR; concluyendo que la inspección óptima está formada por la combinación de ambas técnicas.

  2. Re-evaluating a vision-related quality of life questionnaire with item response theory (IRT) and differential item functioning (DIF) analyses.

    NARCIS (Netherlands)

    Nispen, R.M.A. van; Knol, D.L.; Langelaan, M.; Rens, G.H.M.B. van

    2011-01-01

    Background: For the Low Vision Quality Of Life questionnaire (LVQOL) it is unknown whether the psychometric properties are satisfactory when an item response theory (IRT) perspective is considered. This study evaluates some essential psychometric properties of the LVQOL questionnaire in an IRT

  3. About tunnelling times

    International Nuclear Information System (INIS)

    Olkhovsky, V.S.; Recami, E.

    1991-08-01

    In this paper, first we critically analyse the main theoretical definitions and calculations of the sub-barrier tunnelling and reflection times. Secondly, we propose a new, physically sensible definition of such durations, on the basis of a recent general formalism (already tested for other types of quantum collisions). At last, we discuss some results regarding temporal evolution of the tunnelling processes, and in particular the ''particle'' speed during tunnelling. (author). 36 refs, 1 fig

  4. Investigations of the 0.020-scale 88-OTS Integrated Space Shuttle Vehicle Jet-Plume Model in the NASA/Ames Research Center 11 by11-Foot Unitary Plan Wind Tunnel (IA80). Volume 1

    Science.gov (United States)

    Nichols, M. E.

    1976-01-01

    The results are documented of jet plume effects wind tunnel test of the 0.020-scale 88-OTS launch configuration space shuttle vehicle model in the 11 x 11 foot leg of the NASA/Ames Research Center Unitary Plan Wind Tunnel. This test involved cold gas main propulsion system (MPS) and solid rocket motor (SRB) plume simulations at Mach numbers from 0.6 to 1.4. Integrated vehicle surface pressure distributions, elevon and rudder hinge moments, and wing and vertical tail root bending and torsional moments due to MPS and SRB plume interactions were determined. Nozzle power conditions were controlled per pretest nozzle calibrations. Model angle of attack was varied from -4 deg to +4 deg; model angle of sideslip was varied from -4 deg to +4 deg. Reynolds number was varied for certain test conditions and configurations, with the nominal freestream total pressure being 14.69 psia. Plotted force and pressure data are presented.

  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. Radiation protection, radioactive waste management and site monitoring at the nuclear scientific experimental and educational centre IRT-Sofia at INRNE-BAS.

    Science.gov (United States)

    Mladenov, Al; Stankov, D; Nonova, Tz; Krezhov, K

    2014-11-01

    This article identifies important components and describes the safe practices in implementing radiation protection and radioactive waste management programmes, and in their optimisation at the Nuclear Scientific Experimental and Educational Centre with research reactor IRT at INRNE-BAS. It covers the instrumentation and personal protective equipment and organisational issues related to the continuous site monitoring. The reactor is under major reconstruction and the measures applied to radiation monitoring of environment and working area focused on restricting the radiation exposure of the staff as well as compliance with international good practices related to the environmental and public radiation safety requirements are also addressed. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Rudolf Hermann, wind tunnels and aerodynamics

    Science.gov (United States)

    Lundquist, Charles A.; Coleman, Anne M.

    2008-04-01

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

  8. Time evolution of the energy confinement time, internal inductance and effective edge safety factor on IR-T1 tokamak

    International Nuclear Information System (INIS)

    Salar Elahi, A; Ghoranneviss, M

    2010-01-01

    An attempt is made to investigate the time evolution of the energy confinement time, internal inductance and effective edge safety factor on IR-T1 tokamak. For this purpose, four magnetic pickup coils were designed, constructed and installed on the outer surface of the IR-T1 and then the Shafranov parameter (asymmetry factor) was obtained from them. On the other hand, also a diamagnetic loop was designed and installed on IR-T1 and poloidal beta was determined from it. Therefore, the internal inductance and effective edge safety factor were measured. Also, the time evolution of the energy confinement time was measured using the diamagnetic loop. Experimental results on IR-T1 show that the maximum energy confinement time (which corresponds to minimum collisions, minimum microinstabilities and minimum transport) is at low values of the effective edge safety factor (2.5 eff (a) i <0.72). The results obtained are in agreement with those obtained with the theoretical approach [1-5].

  9. Measuring Anxiety in Visually-Impaired People: A Comparison between the Linear and the Nonlinear IRT Approaches

    Science.gov (United States)

    Ferrando, Pere J.; Pallero, Rafael; Anguiano-Carrasco, Cristina

    2013-01-01

    The present study has two main interests. First, some pending issues about the psychometric properties of the CTAC (an anxiety questionnaire for blind and visually-impaired people) are assessed using item response theory (IRT). Second, the linear model is compared to the graded response model (GRM) in terms of measurement precision, sensitivity…

  10. Scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Binnig, G.; Rohrer, H.

    1983-01-01

    Based on vacuum tunneling, a novel type of microscope, the scanning tunneling microscope (STM) was developed. It has an unprecedented resolution in real space on an atomic scale. The authors review the important technical features, illustrate the power of the STM for surface topographies and discuss its potential in other areas of science and technology. (Auth.)

  11. Electron tunneling in chemistry

    International Nuclear Information System (INIS)

    Zamaraev, K.I.; Khajrutdinov, R.F.; Zhdanov, V.P.; Molin, Yu.N.

    1985-01-01

    Results of experimental and theoretical investigations are outlined systematically on electron tunnelling in chemical reactions. Mechanism of electron transport to great distances is shown to be characteristic to chemical compounds of a wide range. The function of tunnel reactions is discussed for various fields of chemistry, including radiation chemistry, electrochemistry, chemistry of solids, chemistry of surface and catalysis

  12. A Far Infrared Photometer (FIRP) for the infrared telescope in space (IRTS)

    Science.gov (United States)

    Freund, M. M.; Hirao, T.; Matsumoto, T.; Sato, S.; Watabe, T.; Brubaker, G. K.; Duband, L.; Grossman, B.; Larkin, N.; Lumetta, S.; Lange, A. E.

    1993-12-01

    We describe the design and calibration of the Far-Infrared Photometer (FIRP), one of four focal plane instruments on the Infrared Telescope in Space (IRTS). The FIRP will provide absolute photometry in four bands centered at 150, 250, 400, and 700 micrometers with spectral resolution lambda/(Delta lambda) approx. = 3 and spatial resolution Delta theta = 0.5 degrees. High sensitivity is achieved by using bolometric detectors operated at 300 mK in an AC bridge circuit. The closed-cycle He-3 refrigerator can be recycled in orbit. A 2 K shutter provides a zero reference for each field of view. More than 10% of the sky will be surveyed during the approximately 3 week mission lifetime with a sensitivity of less than 10-13 W/((sq cm)(sr)) per 0.5 degree pixel.

  13. A Far Infrared Photometer (FIRP) for the infrared telescope in space (IRTS)

    Science.gov (United States)

    Freund, M. M.; Hirao, T.; Matsumoto, T.; Sato, S.; Watabe, T.; Brubaker, G. K.; Duband, L.; Grossman, B.; Larkin, N.; Lumetta, S.

    1993-01-01

    We describe the design and calibration of the Far-Infrared Photometer (FIRP), one of four focal plane instruments on the Infrared Telescope in Space (IRTS). The FIRP will provide absolute photometry in four bands centered at 150, 250, 400, and 700 micrometers with spectral resolution lambda/(Delta lambda) approx. = 3 and spatial resolution Delta theta = 0.5 degrees. High sensitivity is achieved by using bolometric detectors operated at 300 mK in an AC bridge circuit. The closed-cycle He-3 refrigerator can be recycled in orbit. A 2 K shutter provides a zero reference for each field of view. More than 10% of the sky will be surveyed during the approximately 3 week mission lifetime with a sensitivity of less than 10(exp -13) W/((sq cm)(sr)) per 0.5 degree pixel.

  14. A MATLAB Package for Markov Chain Monte Carlo with a Multi-Unidimensional IRT Model

    Directory of Open Access Journals (Sweden)

    Yanyan Sheng

    2008-11-01

    Full Text Available Unidimensional item response theory (IRT models are useful when each item is designed to measure some facet of a unified latent trait. In practical applications, items are not necessarily measuring the same underlying trait, and hence the more general multi-unidimensional model should be considered. This paper provides the requisite information and description of software that implements the Gibbs sampler for such models with two item parameters and a normal ogive form. The software developed is written in the MATLAB package IRTmu2no. The package is flexible enough to allow a user the choice to simulate binary response data with multiple dimensions, set the number of total or burn-in iterations, specify starting values or prior distributions for model parameters, check convergence of the Markov chain, as well as obtain Bayesian fit statistics. Illustrative examples are provided to demonstrate and validate the use of the software package.

  15. A century of wind tunnels since Eiffel

    Science.gov (United States)

    Chanetz, Bruno

    2017-08-01

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

  16. Results Of Aerosol Measurements In An Austrian Road Tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Imhof, D.; Weingartner, E.; Prevot, A.S.H.; Ordonez, C.; Kurtenbach, R. [BUGHW (Georgia); Rodler, J. [TUG Institute (Australia); Sturm, P. [TUG Institute (Australia); Sjoedin, A. [IVL Institute (Sweden); McCrae, I. [TRL Institute (United Kingdom); Baltensperger, U.

    2005-03-01

    In a comprehensive tunnel study in Graz, Austria, measurements of the particulate and gaseous vehicle emissions were performed in the Plabutsch tunnel. This work was a collaboration of PSI with the Technical University of Graz (TUG), the Bergische Universitaet und Gesamthochschule Wuppertal (BUGHW), the Transport Research Laboratory (TRL) in UK and the Swedish Environmental Research Institute (IVL). (author)

  17. General risks for tunnelling projects: An overview

    Science.gov (United States)

    Siang, Lee Yong; Ghazali, Farid E. Mohamed; Zainun, Noor Yasmin; Ali, Roslinda

    2017-10-01

    Tunnels are indispensable when installing new infrastructure as well as when enhancing the quality of existing urban living due to their unique characteristics and potential applications. Over the past few decades, there has been a significant increase in the building of tunnels, world-wide. Tunnelling projects are complex endeavors, and risk assessment for tunnelling projects is likewise a complex process. Risk events are often interrelated. Occurrence of a technical risk usually carries cost and schedule consequences. Schedule risks typically impact cost escalation and project overhead. One must carefully consider the likelihood of a risk's occurrence and its impact in the context of a specific set of project conditions and circumstances. A project's goals, organization, and environment impacts in the context of a specific set of project conditions and circumstances. Some projects are primarily schedule driven; other projects are primarily cost or quality driven. Whether a specific risk event is perceived fundamentally as a cost risk or a schedule risk is governed by the project-specific context. Many researchers have pointed out the significance of recognition and control of the complexity, and risks of tunnelling projects. Although all general information on a project such as estimated duration, estimated cost, and stakeholders can be obtained, it is still quite difficult to accurately understand, predict and control the overall situation and development trends of the project, leading to the risks of tunnelling projects. This paper reviews all the key risks for tunnelling projects from several case studies that have been carried out by other researchers. These risks have been identified and reviewed in this paper. As a result, the current risk management plan in tunnelling projects can be enhanced by including all these reviewed risks as key information.

  18. Exogenous abscisic acid application decreases cadmium accumulation in Arabidopsis plants, which is associated with the inhibition of IRT1-mediated cadmium uptake

    Directory of Open Access Journals (Sweden)

    Shi Kan eFan

    2014-12-01

    Full Text Available Cadmium (Cd contamination of agricultural soils is an increasingly serious problem. Measures need to be developed to minimise Cd entering the human food chain from contaminated soils. We report here that, under Cd exposure condition, application with low doses of (0.1–0.5 μM abscisic acid (ABA clearly inhibited Cd uptake by roots and decreased Cd level in Arabidopsis wild-type plants (Col-0. Expression of IRT1 in roots was also strongly inhibited by ABA treatment. Decrease in Cd uptake and the inhibition of IRT1 expression were clearly lesser pronounced in an ABA-insensitive double mutant snrk2.2/2.3 than in the Col-0 in response to ABA application. The ABA-decreased Cd uptake was found to correlate with the ABA-inhibited IRT1 expression in the roots of Col-0 plants fed two different levels of iron. Furthermore, the Cd uptake of irt1 mutants was barely affected by ABA application. These results indicated that inhibition of IRT1 expression is involved in the decrease of Cd uptake in response to exogenous ABA application. Interestingly, ABA application increased the iron level in both Col-0 plants and irt1 mutants, suggesting that ABA-increased Fe acquisition does not depend on the IRT1 function, but on the contrary, the ABA-mediated inhibition of IRT1 expression may be due to the elevation of iron level in plants. From our results, we concluded that ABA application might increase iron acquisition, followed by the decrease in Cd uptake by inhibition of IRT1 activity. Thus, for crop production in Cd contaminated soils, developing techniques based on ABA application potentially is a promising approach for reducing Cd accumulation in edible organs in plants.

  19. Ultrafast scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

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

  20. Numerical modelling of air movement in road tunnels

    International Nuclear Information System (INIS)

    Kashef, A.; Benichou, N.; Lougheed, G. . E-mail; Debs, A.

    2003-01-01

    The objective of the Mechanical Ventilation Systems (MVS) in highway tunnels is to provide tunnel patrons with a reasonable degree of comfort during normal operation and to assist in keeping tunnels safe during emergencies. Temperature, humidity, and air velocity are among the parameters that determine the tunnel environment and indicate the level of MVS performance. To investigate the performance of the current emergency ventilation strategies for an existing tunnel system in the event of a fire, a research project is being conducted at the National Research Council of Canada. The primary objectives of the study are: a) to assess and validate the ability of in-place emergency ventilation strategies to control smoke spread and minimize the impact of smoke on tunnel users; and b) to recommend guidelines for improving ventilation operation to maximize intervention effectiveness. This will allow future development of an intelligent ventilation system based on a pre-established scenario of ventilation activated using automatic fire detection. The research study includes two phases, numerical and experimental phases. The numerical phase will use a CFD model (Solvent) to study smoke ventilation in the tunnel. The experimental phase will be used to calibrate and validate the CFD model and to establish the boundary conditions for the numerical model. Solvent was used to model a ventilation scenario using existing data. The current paper presents the initial efforts to validate the CFD model against onsite flow measurements conducted in the tunnel. The CFD model included aerodynamically significant physical features of the tunnel. (author)

  1. Wind Tunnel Facility

    Data.gov (United States)

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

  2. Quantum tunneling with friction

    Science.gov (United States)

    Tokieda, M.; Hagino, K.

    2017-05-01

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

  3. 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...

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

    Science.gov (United States)

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

    2010-01-01

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

  5. New vision of magnetic tunnelling

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, Jonathan R. [Amherst College, Amhurst, MA (United States)

    2002-01-01

    Recent experiments support the idea that crystal defects may be responsible for the quantum tunnelling of magnetic moments in molecular magnets at low temperatures. The magnetic moment of a typical bar magnet will never spontaneously reverse direction. However, thermal fluctuations can flip the moment of a magnetic particle just a few nanometres across. The particle can be cooled to nearly absolute zero to suppress this process, but the moment may still find a way to reverse via quantum tunnelling. Quantum tunnelling of magnetization has been the subject of decades of research. Until a few years ago, however, there had only been circumstantial evidence for the phenomenon. This is because most systems of small magnetic particles are hard to characterize - the particles have a variety of shapes, sizes and other properties, making it difficult to compare data with theory. Some real progress was made a few years ago through research into high-spin single-molecule magnets. With dimensions of about a nanometre, these magnets are usually composed of a magnetic core that is surrounded by organic complexes. When they crystallize into a regular lattice, the organic ions keep neighbouring magnets well separated so that they interact only weakly. Ideally all the molecules are identical because they have been built chemically, which means that they can be characterized precisely and that any data can be analysed quantitatively. The most studied of these molecules is manganese-12 acetate (Mn{sub 12}). Within each molecule, the spins of the eight Mn{sup 3+} ions (each with S=2) are antiparallel to the spins of the four Mn{sup 4+} ions (each with S=3/2), giving Mn{sub 12} a total spin of S=10. Or, to put it another way, the magnetic moment of Mn{sub 12} is 20 times larger than that of the electron. Now Eugene Chudnovsky of Lehman College in New York and Dmitry Garanin of the University of Mainz in Germany have suggested a new mechanism for producing tunnelling in Mn{sub 12

  6. Design and Preliminary Results of a Feedback Circuit for Plasma Displacement Control in IR-T1 Tokamak

    International Nuclear Information System (INIS)

    TalebiTaher, A.; Ghoranneviss, M.; Tarkeshian, R.; Salem, M. K.; Khorshid, P.

    2008-01-01

    Since displacement is very important for plasma position control, in IR-T1 tokamak a combination of two cosine coils and two saddle sine coils is used for horizontal displacement measurement. According to the multiple moment theory, the output of these coils linearly depends to radial displacement of plasma column. A new circuit for adding these signals to feedback system designed and unwanted effects of other fields in final output compensated. After compensation and calibration of the system, the output of horizontal displacement circuits applied to feedback control system. By considers the required auxiliary vertical field, a proportional amplifier and driver circuit are constructed to drive power transistors these power transistors switch the feedback bank capacitors. In the experiment, a good linear proportionality between displacement and output observed by applying an appropriate feedback field, the linger confinement time in IR-T1 tokamak obtained, applying this system to discharge increased the plasma duration and realizes repetitive discharges

  7. Fire Resistant Panels for the Tunnel Linings

    Directory of Open Access Journals (Sweden)

    Gravit Marina

    2016-01-01

    Full Text Available Presents the results of studies of innovative materials in the field of experimental and theoretical research fire resistance fireproof panels Pyro-Safe Aestuver T. Owing to the assembly simplicity, materials cheapness, high ecological standard, recycling, reuse potential, are benefit. Research work is running to improve the knowledge about fireproof panels Pyro-Safe Aestuver T for tunnel lining, its basic performance, its long term behavior and in particular also its fire proof for example when used for the lining of road tunnels.

  8. 1 Ft. x 1 Ft. Supersonic Wind Tunnel, Bldg. 37

    Data.gov (United States)

    Federal Laboratory Consortium — The 1- by 1-Foot Supersonic Wind Tunnel (1x), located in the Engine Research Building, is one of the most active test facilities at the Glenn Research Center. Used...

  9. Experimental Investigation on an Energy Efficient Solar Tunnel Dryer

    OpenAIRE

    M. R. Seshan Ram

    2012-01-01

    The research determines the effectiveness of the solar tunnel dryer developed and the product dried in the device is superior in quality and also it is compatible with branded products available in the market. The study also determines Acetamide as Phase Key words: Solar Tunnel Dryer, Acetamide as Phase Change Materials, Conversion into Thermal Energy, Thermocouple, and Pyranometer

  10. Floating frame grounding system. [for wind tunnel static force measurement

    Science.gov (United States)

    Forsyth, T. J.

    1987-01-01

    The development of a floating frame grounding system (FFGS) for the 40- by 80-foot low speed wind tunnel facility at the NASA Ames Research Center National Full Scale Aerodynamics Complex is addresssed. When electrical faults are detected, the FFGS ensures a ground path for the fault current. In addition, the FFGS alerts the tunnel operator when a mechanical foul occurs.

  11. Developing a Screening Inventory Reading Test (IRT for the Isfahanian Students of the First to Fifth Grade

    Directory of Open Access Journals (Sweden)

    Bijan Shafiei

    2009-12-01

    Full Text Available Background and aim: Reading is one of the most essential skills in this century. Reading disorders can cause several problems for the person who has reading disorder. Early assessment and diagnosis play an important role in treatment of this disorder. The main purpose of this study was to develope a screening inventory reading test (IRT for first to fifth grade student in Isfahan in order to early diagnosis of reading disorder.Materials and Methods: The test, consisting of 100 words context and four comprehension questions, named Inventory Reading Test (IRT, was evaluated by several speech therapists. It was standardized by testing on one thousand boys and girls, 200 students in every grade, that were selected through a multi-stage random sampling method. Test was performed on two other groups, a normal and a reading-disordered.Results: Scores of reading accuracy and velocity were highly correlated with the test total score. Test reliability was calculated as 0.77 by Cronbach`s alpha measure. There was significant difference between two groups mean score (p=0.01.Conclusion: IRT seems to be an appropriate tool for screening reading disorder of first to fifth grade students.

  12. Robustness of the charge-ordered phases in IrTe2 against photoexcitation

    Science.gov (United States)

    Monney, C.; Schuler, A.; Jaouen, T.; Mottas, M.-L.; Wolf, Th.; Merz, M.; Muntwiler, M.; Castiglioni, L.; Aebi, P.; Weber, F.; Hengsberger, M.

    2018-02-01

    We present a time-resolved angle-resolved photoelectron spectroscopy study of IrTe2, which undergoes two first-order structural and charge-ordered phase transitions on cooling below 270 K and below 180 K. The possibility of inducing a phase transition by photoexcitation with near-infrared femtosecond pulses is investigated in the charge-ordered phases. We observe changes of the spectral function occurring within a few hundreds of femtoseconds and persisting up to several picoseconds, which we interpret as a partial photoinduced phase transition (PIPT). The necessary time for photoinducing these spectral changes increases with increasing photoexcitation density and reaches time scales longer than the rise time of the transient electronic temperature. We conclude that the PIPT is driven by a transient increase of the lattice temperature following the energy transfer from the electrons. However, the photoinduced changes of the spectral function are small, which indicates that the low-temperature phase is particularly robust against photoexcitation. We suggest that the system might be trapped in an out-of-equilibrium state, for which only a partial structural transition is achieved.

  13. Combined application of OGTT, IRT and CPRT for diagnosis and treatment of type 2 diabetes mellitus

    International Nuclear Information System (INIS)

    Wei Zikun; Yang Xiaoli; Tian Zhufang

    2006-01-01

    Objective: To assess the value of combined clinical application of oral glucose tolerance test (OGTT), insulin release test (IRT) and C-peptide release test (CPRT) for the diagnosis and treatment of type 2 diabetes mellitus (DM2). Methods: Retrospect analysis of the data of the results of these three tests in 217 subjects examined was performed. Results: (1) Among the 217 subjects, 71 of them were not diagnosed as diabetics. However, upon further scrutinization of the data, 49 (69%) should be classified as diabetics. Fasting blood sugar (FPG) levels were normal in 53% of the 49, but 2h PG levels were mostly elevated with the exception of only 4 (4/49, 8%), Therefore, 2h PG levels were much more useful for screening of diabetes than FPG levels were. (2) Treatment result in these patients was not very satisfactory: only 24% of the patients (35/146) had their disease well-controlled. Conclusion: Combined clinical application of OGTT, ITR and CPRT would enhance the diagnostic accuracy of diabetes with fewer cases missed. (authors)

  14. Mathematical Ability and Socio-Economic Background: IRT Modeling to Estimate Genotype by Environment Interaction.

    Science.gov (United States)

    Schwabe, Inga; Boomsma, Dorret I; van den Berg, Stéphanie M

    2017-12-01

    Genotype by environment interaction in behavioral traits may be assessed by estimating the proportion of variance that is explained by genetic and environmental influences conditional on a measured moderating variable, such as a known environmental exposure. Behavioral traits of interest are often measured by questionnaires and analyzed as sum scores on the items. However, statistical results on genotype by environment interaction based on sum scores can be biased due to the properties of a scale. This article presents a method that makes it possible to analyze the actually observed (phenotypic) item data rather than a sum score by simultaneously estimating the genetic model and an item response theory (IRT) model. In the proposed model, the estimation of genotype by environment interaction is based on an alternative parametrization that is uniquely identified and therefore to be preferred over standard parametrizations. A simulation study shows good performance of our method compared to analyzing sum scores in terms of bias. Next, we analyzed data of 2,110 12-year-old Dutch twin pairs on mathematical ability. Genetic models were evaluated and genetic and environmental variance components estimated as a function of a family's socio-economic status (SES). Results suggested that common environmental influences are less important in creating individual differences in mathematical ability in families with a high SES than in creating individual differences in mathematical ability in twin pairs with a low or average SES.

  15. Single Electron Tunneling

    International Nuclear Information System (INIS)

    Ruggiero, Steven T.

    2005-01-01

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

  16. 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.

  17. Model design and instrumentation experiences with continuous-flow cryogenic tunnels

    Science.gov (United States)

    Kilgore, R. A.

    1980-01-01

    The development of wind tunnels that can be operated at cryogenic temperatures has placed several new demands on the ability to build and instrument wind tunnel models. The experiences at the NASA Langley Research Center relative to the design and instrumentation of models for continuous flow cryogenic wind tunnels are reviewed.

  18. Interaction between groundwater and TBM (Tunnel Boring Machine) excavated tunnels

    OpenAIRE

    Font Capó, Jordi

    2012-01-01

    A number of problems, e.g. sudden inflows are encountered during tunneling under the piezometric level, especially when the excavation crosses high transmissivity areas. These inflows may drag materials when the tunnel crosses low competent layers, resulting in subsidence, chimney formation and collapses. Moreover, inflows can lead to a decrease in head level because of aquifer drainage. Tunnels can be drilled by a tunnel boring machine (TBM) to minimize inflows and groundwater impacts, restr...

  19. A method for data base management and analysis for wind tunnel data

    Science.gov (United States)

    Biser, Aileen O.

    1987-01-01

    To respond to the need for improved data base management and analysis capabilities for wind-tunnel data at the Langley 16-Foot Transonic Tunnel, research was conducted into current methods of managing wind-tunnel data and a method was developed as a solution to this need. This paper describes the development of the data base management and analysis method for wind-tunnel data. The design and implementation of the software system are discussed and examples of its use are shown.

  20. Seepage into PEP tunnel

    International Nuclear Information System (INIS)

    Weidner, H.

    1990-01-01

    The current rate of seepage into the PEP tunnel in the vicinity of IR-10 is very low compared to previous years. Adequate means of handling this low flow are in place. It is not clear whether the reduction in the flow is temporary, perhaps due to three consecutive dry years, or permanent due to drainage of a perched water table. During PEP construction a large amount of effort was expended in attempts to seal the tunnel, with no immediate effect. The efforts to ''manage'' the water flow are deemed to be successful. By covering equipment to protect it from dripping water and channeling seepage into the drainage gutters, the seepage has been reduced to a tolerable nuisance. There is no sure, safe procedure for sealing a leaky shotcreted tunnel

  1. Excavating a transfer tunnel

    CERN Multimedia

    Laurent Guiraud

    2000-01-01

    The transfer tunnel being dug here will take the 450 GeV beam from the SPS and inject it into the LHC where the beam energies will be increased to 7 TeV. In order to transfer this beam from the SPS to the LHC, two transfer tunnels are used to circulate the beams in opposite directions. When excavated, the accelerator components, including magnets, beam pipes and cryogenics will be installed and connected to both the SPS and LHC ready for operation to begin in 2008.

  2. Complex use of heat-exchange tunnels

    Directory of Open Access Journals (Sweden)

    А. Ф. Галкин

    2017-04-01

    Full Text Available The paper presents separate results of complex research (experimental and theoretical on the application of heat-exchange tunnels – in frozen rocks, among other things – as underground constructions serving two purposes. It is proposed to use heat-exchange tunnels as a separate multi-functional module, which under normal conditions will be used to set standards of heat regime parameters in the mines, and in emergency situations, natural or man-made, will serve as a protective structure to shelter mine workers. Heat-exchange modules can be made from mined-out or specially constructed tunnels. Economic analysis shows that the use of such multi-functional modules does not increase operation and maintenance costs, but enhances safety of mining operations and reliability in case of emergency situations. There are numerous theoretic and experimental investigations in the field of complex use of mining tunnels, which allows to develop regulatory design documents on their basis. Experience of practical application of heat-exchange tunnels has been assessed from the position of regulating heat regime in the mines.

  3. Application Of Artificial Intelligence To Wind Tunnels

    Science.gov (United States)

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

    1989-01-01

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

  4. Breaking through the tranfer tunnel

    CERN Document Server

    Laurent Guiraud

    2001-01-01

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

  5. Gap anisotropy and tunneling currents. [MPS3

    DEFF Research Database (Denmark)

    Lazarides, N.; Sørensen, Mads Peter

    1996-01-01

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

  6. Nonlinear tunneling in two-dimensional lattices

    Czech Academy of Sciences Publication Activity Database

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

    2007-01-01

    Roč. 76, č. 2 (2007), 023608.1-023608.14 ISSN 1050-2947 R&D Projects: GA MŠk(CZ) OC P11.001 Institutional research plan: CEZ:AV0Z20670512 Keywords : Bose -WEinstein condensation * tunnelling Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.893, year: 2007

  7. Positioning systems for underground tunnel environments

    CERN Document Server

    Leite Pereira, Fernando; Theis, Christian

    In the last years the world has witnessed a remarkable change in the computing concept by entering the mobile era. Incredibly powerful smartphones have proliferated at stunning pace and tablet computers are capable of running demanding applications and meet new business requirements. Being wireless, localization has become crucial not only to serve individuals but also help companies in industrial and safety processes. In the context of the Radiation Protection group at CERN, automatic localization, besides allowing to find people, would help improving the radiation surveys performed regularly along the accelerator tunnels. The research presented in this thesis attempts to answer questions relatively to the viability of localization in a harsh conditions tunnel: “Is localization in a very long tunnel possible, meeting its restrictions and without incurring prohibitive costs and infrastructure?”, “Can one achieve meter-level accuracy with GSM deployed over leaky-feeder?”, “Is it possible to prototype...

  8. Unstable Semiclassical Trajectories in Tunneling

    CERN Document Server

    Levkov, D G; Sibiryakov, S M

    2007-01-01

    Some tunneling phenomena are described, in the semiclassical approximation, by unstable complex trajectories. We develop a systematic procedure to stabilize the trajectories and to calculate the tunneling probability, including both the suppression exponent and prefactor. We find that the instability of tunneling solutions modifies the power-law dependence of the prefactor on h as compared to the case of stable solutions.

  9. Building information modelling review with potential applications in tunnel engineering of China.

    Science.gov (United States)

    Zhou, Weihong; Qin, Haiyang; Qiu, Junling; Fan, Haobo; Lai, Jinxing; Wang, Ke; Wang, Lixin

    2017-08-01

    Building information modelling (BIM) can be applied to tunnel engineering to address a number of problems, including complex structure, extensive design, long construction cycle and increased security risks. To promote the development of tunnel engineering in China, this paper combines actual cases, including the Xingu mountain tunnel and the Shigu Mountain tunnel, to systematically analyse BIM applications in tunnel engineering in China. The results indicate that BIM technology in tunnel engineering is currently mainly applied during the design stage rather than during construction and operation stages. The application of BIM technology in tunnel engineering covers many problems, such as a lack of standards, incompatibility of different software, disorganized management, complex combination with GIS (Geographic Information System), low utilization rate and poor awareness. In this study, through summary of related research results and engineering cases, suggestions are introduced and an outlook for the BIM application in tunnel engineering in China is presented, which provides guidance for design optimization, construction standards and later operation maintenance.

  10. Building information modelling review with potential applications in tunnel engineering of China

    Science.gov (United States)

    Zhou, Weihong; Qin, Haiyang; Qiu, Junling; Fan, Haobo; Lai, Jinxing; Wang, Ke; Wang, Lixin

    2017-08-01

    Building information modelling (BIM) can be applied to tunnel engineering to address a number of problems, including complex structure, extensive design, long construction cycle and increased security risks. To promote the development of tunnel engineering in China, this paper combines actual cases, including the Xingu mountain tunnel and the Shigu Mountain tunnel, to systematically analyse BIM applications in tunnel engineering in China. The results indicate that BIM technology in tunnel engineering is currently mainly applied during the design stage rather than during construction and operation stages. The application of BIM technology in tunnel engineering covers many problems, such as a lack of standards, incompatibility of different software, disorganized management, complex combination with GIS (Geographic Information System), low utilization rate and poor awareness. In this study, through summary of related research results and engineering cases, suggestions are introduced and an outlook for the BIM application in tunnel engineering in China is presented, which provides guidance for design optimization, construction standards and later operation maintenance.

  11. Tunnelling with wormhole creation

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-15

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

  12. Tunnelling with wormhole creation

    OpenAIRE

    Ansoldi, Stefano; Tanaka, Takahiro

    2014-01-01

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

  13. Tunnelling Effects in Chemistry

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 2. Tunnelling Effects in Chemistry: Molecules in the Strange Quantum World. Sharmistha Karmakar Deepthi Jose Ayan Datta. General Article Volume 19 Issue 2 February 2014 pp 160-174 ...

  14. INCAS SUBSONIC WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Corneliu STOICA

    2009-09-01

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

  15. The Channel Tunnel

    Science.gov (United States)

    2006-01-01

    The Channel Tunnel is a 50.5 km-long rail tunnel beneath the English Channel at the Straits of Dover. It connects Dover, Kent in England with Calais, northern France. The undersea section of the tunnel is unsurpassed in length in the world. A proposal for a Channel tunnel was first put forward by a French engineer in 1802. In 1881, a first attempt was made at boring a tunnel from the English side; the work was halted after 800 m. Again in 1922, English workers started boring a tunnel, and advanced 120 m before it too was halted for political reasons. The most recent attempt was begun in 1987, and the tunnel was officially opened in 1994. At completion it was estimated that the project cost around $18 billion. It has been operating at a significant loss since its opening, despite trips by over 7 million passengers per year on the Eurostar train, and over 3 million vehicles per year. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance. The

  16. Experimental Evaluation of Turning Vane Designs for High-speed and Coupled Fan-drive Corners of 0.1-scale Model of NASA Lewis Research Center's Proposed Altitude Wind Tunnel

    Science.gov (United States)

    Gelder, Thomas F.; Moore, Royce D.; Shyne, Rickey J.; Boldman, Donald R.

    1987-01-01

    Two turning vane designs were experimentally evaluated for the fan-drive corner (corner 2) coupled to an upstream diffuser and the high-speed corner (corner 1) of the 0.1 scale model of NASA Lewis Research Center's proposed Altitude Wind Tunnel. For corner 2 both a controlled-diffusion vane design (vane A4) and a circular-arc vane design (vane B) were studied. The corner 2 total pressure loss coefficient was about 0.12 with either vane design. This was about 25 percent less loss than when corner 2 was tested alone. Although the vane A4 design has the advantage of 20 percent fewer vanes than the vane B design, its vane shape is more complex. The effects of simulated inlet flow distortion on the overall losses for corner 1 or 2 were small.

  17. Acoustic Performance of the GEAE UPS Research Fan in the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel

    Science.gov (United States)

    Woodward, Richard P.; Hughes, Christopher E.

    2012-01-01

    A model advanced turbofan was acoustically tested in the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel in 1994. The Universal Propulsion Simulator fan was designed and manufactured by General Electric Aircraft Engines, and included an active core, as well as bypass, flow paths. The fan was tested with several rotors featuring unswept, forward-swept and aft-swept designs of both metal and composite construction. Sideline acoustic data were taken with both hard and acoustically treated walls in the flow passages. The fan was tested within an airflow at a Mach number of 0.20, which is representative of aircraft takeoff/approach conditions. All rotors showed similar aerodynamic performance. However, the composite rotors typically showed higher noise levels than did corresponding metal rotors. Aft and forward rotor sweep showed at most modest reductions of transonic multiple pure tone levels. However, rotor sweep often introduced increased rotor-stator interaction tone levels. Broadband noise was typically higher for the composite rotors and also for the aft-swept metal rotor. Transonic MPT generation was reduced with increasing fan axis angle of attack (AOA); however, higher downstream noise levels did increase with AOA resulting in higher overall Effective Perceived Noise Level.

  18. Measuring fire size in tunnels

    International Nuclear Information System (INIS)

    Guo, Xiaoping; Zhang, Qihui

    2013-01-01

    A new measure of fire size Q′ has been introduced in longitudinally ventilated tunnel as the ratio of flame height to the height of tunnel. The analysis in this article has shown that Q′ controls both the critical velocity and the maximum ceiling temperature in the tunnel. Before the fire flame reaches tunnel ceiling (Q′ 1.0), Fr approaches a constant value. This is also a well-known phenomenon in large tunnel fires. Tunnel ceiling temperature shows the opposite trend. Before the fire flame reaches the ceiling, it increases very slowly with the fire size. Once the flame has hit the ceiling of tunnel, temperature rises rapidly with Q′. The good agreement between the current prediction and three different sets of experimental data has demonstrated that the theory has correctly modelled the relation among the heat release rate of fire, ventilation flow and the height of tunnel. From design point of view, the theoretical maximum of critical velocity for a given tunnel can help to prevent oversized ventilation system. -- Highlights: • Fire sizing is an important safety measure in tunnel design. • New measure of fire size a function of HRR of fire, tunnel height and ventilation. • The measure can identify large and small fires. • The characteristics of different fire are consistent with observation in real fires

  19. WTSETUP: Software for Creating and Editing Configuration Files in the Low Speed Wind Tunnel Data Acquisition System

    National Research Council Canada - National Science Library

    Edwards, Craig

    1999-01-01

    The Data Acquisition System in the Low Speed Wind Tunnel at the Aeronautical and Maritime Research Laboratory is responsible for the measurement, recording, processing and displaying of wind tunnel test data...

  20. Results of an investigation to determine local flow characteristics at the air data probe locations using an 0.030-scale model (45-0) of the space shuttle vehicle orbiter configuration 140A/B (modified) in the NASA Ames Research Center unitary plan wind tunnel (OA161, A, B, C), volume 1

    Science.gov (United States)

    Nichols, M. E.

    1976-01-01

    Results are presented of wind tunnel test 0A161 of a 0.030-scale model 45-0 of the configuration 140A/B (modified) space shuttle vehicle orbiter in the NASA Ames Research Center Unitary Plan Wind Tunnel facilities. The purpose of this test was to determine local total and static pressure environments for the air data probe locations and relative effectiveness of alternate flight-test probe configurations. Testing was done in the Mach number range from 0.30 to 3.5. Angle of attack was varied from -8 to 25 degrees while sideslip varied between -8 and 8 degrees.

  1. Britain's delegation to CERN, the European Centre for Nuclear Research near Geneva, voted in favour of a project which take seven years to build, involve a 27 kilometre long tunnel, and cost 230 million pounds. Now LEP receives the go-ahead later this month

    CERN Multimedia

    Llewellyn Smith, Christopher Hubert

    1981-01-01

    Britain's delegation to CERN, the European Centre for Nuclear Research near Geneva, voted in favour of a project which take seven years to build, involve a 27 kilometre long tunnel, and cost 230 million pounds. Now LEP receives the go-ahead later this month

  2. 19 April 2013 - The University of Chicago Vice President for Research and for National Laboratories D. H. Levy signing the guest book with CERN Director for Accelerators and Technology S. Myers; in the LHC tunnel with L. Bottura; throughout accompanied by US CMS J. Butler. Mrs Levy and Mrs Butler took part.

    CERN Multimedia

    Anna Pantelia

    2013-01-01

    19 April 2013 - The University of Chicago Vice President for Research and for National Laboratories D. H. Levy signing the guest book with CERN Director for Accelerators and Technology S. Myers; in the LHC tunnel with L. Bottura; throughout accompanied by US CMS J. Butler. Mrs Levy and Mrs Butler took part.

  3. 17 September 2013 - Estonian Minister of Education and Research J. Aaviksoo signing the guest book with CERN Director-General R- Heuer; visiting the TOTEM facility with TOTEM Collaboration Spokesperson S. Giani; in the LHC tunnel at Point 5 with International Relations Adviser T. Kurtyka and visiting the CMS cavern with CMS Collaboration Spokesperson J. Incandela. International Relations Adviser R. Voss present.

    CERN Multimedia

    Anna Pantelia

    2013-01-01

    17 September 2013 - Estonian Minister of Education and Research J. Aaviksoo signing the guest book with CERN Director-General R- Heuer; visiting the TOTEM facility with TOTEM Collaboration Spokesperson S. Giani; in the LHC tunnel at Point 5 with International Relations Adviser T. Kurtyka and visiting the CMS cavern with CMS Collaboration Spokesperson J. Incandela. International Relations Adviser R. Voss present.

  4. 26 Feburary 2013 - Mexican Secretary of Foreign Affairs J. A. Meade Kuribreña welcomed by CERN Director-General R. Heuer at LHC Point 2, signing the guest book with Director for Research and Scientific Computing S. Bertolucci, visiting the ALICE experiment and LHC tunnel with Collaboration Deputy Spokesperson Y. Schutz.

    CERN Multimedia

    Laurent Egli; Alice

    2013-01-01

    26 Feburary 2013 - Mexican Secretary of Foreign Affairs J. A. Meade Kuribreña welcomed by CERN Director-General R. Heuer at LHC Point 2, signing the guest book with Director for Research and Scientific Computing S. Bertolucci, visiting the ALICE experiment and LHC tunnel with Collaboration Deputy Spokesperson Y. Schutz.

  5. 18 February 2013 - Foundation for Polish Science President M. Zylicz signing the guest book with CERN Director for Research and Scientific Computing S. Bertolucci; visiting the ALICE experimental cavern with K. Safarik and L. Graczykowskind LHC tunnel with Technology Department A. Siemko.

    CERN Multimedia

    Samuel Morier-Genoud

    2013-01-01

    18 February 2013 - Foundation for Polish Science President M. Zylicz signing the guest book with CERN Director for Research and Scientific Computing S. Bertolucci; visiting the ALICE experimental cavern with K. Safarik and L. Graczykowskind LHC tunnel with Technology Department A. Siemko.

  6. Nanowire resonant tunneling diodes

    Science.gov (United States)

    Björk, M. T.; Ohlsson, B. J.; Thelander, C.; Persson, A. I.; Deppert, K.; Wallenberg, L. R.; Samuelson, L.

    2002-12-01

    Semiconductor heterostructures and their implementation into electronic and photonic devices have had tremendous impact on science and technology. In the development of quantum nanoelectronics, one-dimensional (1D) heterostructure devices are receiving a lot of interest. We report here functional 1D resonant tunneling diodes obtained via bottom-up assembly of designed segments of different semiconductor materials in III/V nanowires. The emitter, collector, and the central quantum dot are made from InAs and the barrier material from InP. Ideal resonant tunneling behavior, with peak-to-valley ratios of up to 50:1 and current densities of 1 nA/μm2 was observed at low temperatures.

  7. Annual report of the working group 'fuel pin and fuel element mechanics' of the Institut fuer Reaktortechnik (IRT) of the Technische Hochschule Darmstadt for the Fast Breeder Project

    International Nuclear Information System (INIS)

    Fabian, H.; Humbach, W.; Lassmann, K.; Mueller, J.J.; Preusser, T.; Schmelz, K.

    1978-09-01

    This report comprises six single lectures given at an information meeting organized by the Institut fuer Reaktortechnik der Technischen Hochschule Darmstadt (IRT) in Darmstadt on April 24, 1978. The lectures are an account of work performed at IRT on the mechanics of fuel pins and fuel elements and supported by the Fast Breeder Project (PSB) of KfK. These activities can be broken down into studies of the integral fuel pin (URANUS computer code) and into multidimensional studies of the fuel pin using the finite-element method (FINEL and ZIDRIG computer codes). Moreover, a report is presented of the status of the test facility for simulation of out-of-pile cladding tube loads and of the IRT project on the simulation and analysis of radiation damage. (orig./GL) [de

  8. Hawking Radiation As Tunneling

    International Nuclear Information System (INIS)

    Parikh, Maulik K.; Wilczek, Frank

    2000-01-01

    We present a short and direct derivation of Hawking radiation as a tunneling process, based on particles in a dynamical geometry. The imaginary part of the action for the classically forbidden process is related to the Boltzmann factor for emission at the Hawking temperature. Because the derivation respects conservation laws, the exact spectrum is not precisely thermal. We compare and contrast the problem of spontaneous emission of charged particles from a charged conductor

  9. The beam dump tunnels

    CERN Multimedia

    Patrice Loïez

    2002-01-01

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

  10. Carpal tunnel release

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  11. Tunnel blasting - recent developments

    Energy Technology Data Exchange (ETDEWEB)

    White, T.E.

    1999-05-01

    While tunnelling machines are more efficient than previously, there are still areas where blasting is a more efficient method of advance. Drilling and design methods are increasingly sophisticated, as is choice of explosive. Explosive deployment must be carefully calculated so as to avoid desensitisation. Nitroglycerine may be used as slurries; bulk mixing on site of ANFO is also practised in mining in the UK. Electric detonators, Nonel tubes, and electronic detonators are also increasingly employed.

  12. Wind Tunnel Management and Resource Optimization: A Systems Modeling Approach

    Science.gov (United States)

    Jacobs, Derya, A.; Aasen, Curtis A.

    2000-01-01

    Time, money, and, personnel are becoming increasingly scarce resources within government agencies due to a reduction in funding and the desire to demonstrate responsible economic efficiency. The ability of an organization to plan and schedule resources effectively can provide the necessary leverage to improve productivity, provide continuous support to all projects, and insure flexibility in a rapidly changing environment. Without adequate internal controls the organization is forced to rely on external support, waste precious resources, and risk an inefficient response to change. Management systems must be developed and applied that strive to maximize the utility of existing resources in order to achieve the goal of "faster, cheaper, better". An area of concern within NASA Langley Research Center was the scheduling, planning, and resource management of the Wind Tunnel Enterprise operations. Nine wind tunnels make up the Enterprise. Prior to this research, these wind tunnel groups did not employ a rigorous or standardized management planning system. In addition, each wind tunnel unit operated from a position of autonomy, with little coordination of clients, resources, or project control. For operating and planning purposes, each wind tunnel operating unit must balance inputs from a variety of sources. Although each unit is managed by individual Facility Operations groups, other stakeholders influence wind tunnel operations. These groups include, for example, the various researchers and clients who use the facility, the Facility System Engineering Division (FSED) tasked with wind tunnel repair and upgrade, the Langley Research Center (LaRC) Fabrication (FAB) group which fabricates repair parts and provides test model upkeep, the NASA and LARC Strategic Plans, and unscheduled use of the facilities by important clients. Expanding these influences horizontally through nine wind tunnel operations and vertically along the NASA management structure greatly increases the

  13. Resonant Tunneling Spin Pump

    Science.gov (United States)

    Ting, David Z.

    2007-01-01

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

  14. Potential application of thermography (IRT) in animal production and for animal welfare. A case report of working dogs.

    Science.gov (United States)

    Redaelli, Veronica; Ludwig, Nicola; Nanni Costa, Leonardo; Crosta, Lorenzo; Riva, Jacopo; Luzi, Fabio

    2014-01-01

    The authors describe the thermography technique in animal production and in veterinary medicine applications. The thermographic technique lends itself to countless applications in biology, thanks to its characteristics of versatility, lack of invasiveness and high sensitivity. Probably the major limitation to most important aspects for its application in the animal lies in the ease of use and in its extreme sensitivity. This review provides an overview of the possible applications of the technique of thermo visual inspection, but it is clear that every phenomenon connected to temperature variations can be identified with this technique. Then the operator has to identify the best experimental context to obtain as much information as possible, concerning the physiopathological problems considered. Furthermore, we reported an experimental study about the thermography (IRT) as a noninvasive technique to assess the state of wellbeing in working dogs. The first results showed the relationship between superficial temperatures and scores obtained by the animal during the behavioral test. This result suggests an interesting application of infrared thermography (IRT) to measure the state of wellbeing of animals in a noninvasive way.

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

    Science.gov (United States)

    Zandvliet, Harold J. W.; Lin, Nian

    2010-07-01

    out the potential landscape of the system (often a molecule or an atom) under study [4, 5]. However, the dynamical processes might also be induced by the tunnelling process itself [6, 7]. In the field of molecular science, excited single molecule experiments have been especially performed [8]. As a nice example, we refer to the work of Sykes' group [9] on thioether molecular rotors. In addition, several groups explore the possibility of combining time-resolved scanning tunnelling microscopy with optical techniques [10, 11]. Although the majority of studies that have been performed so far focus on rather simple systems under nearly ideal and well-defined conditions, we anticipate that time-resolved scanning tunnelling microscopy can also be applied in other research areas, such as biology and soft condensed matter, where the experimental conditions are often less ideal. We hope that readers will enjoy this collection of papers and that it will trigger them to further explore the possibilities of this simple, but powerful technique. References [1] Besenbacher F, Laegsgaard E and Stengaard I 2005 Mater. Today 8 26 [2] van Houselt A and Zandvliet H J W 2010 Rev. Mod. Phys. 82 1593 [3] Tringides M C and Hupalo M 2010 J. Phys.: Condens. Matter 22 264002 [4] Ronci F, Colonna S, Cricenti A and Le Lay G 2010 J. Phys.: Condens. Matter 22 264003 [5] van Houselt A, Poelsema B and Zandvliet H J W 2010 J. Phys.: Condens. Matter 22 264004 [6] Sprodowski C, Mehlhorn M and Morgenstern K 2010 J. Phys.: Condens. Matter 22 264005 [7] Saedi A, Poelsema B and Zandvliet H J W 2010 J. Phys.: Condens. Matter 22 264007 [8] Sloan P A 2010 J. Phys.: Condens. Matter 22 264001 [9] Jewell A D, Tierney H L, Baber A E, Iski E V, Laha M M and Sykes E C H 2010 J. Phys.: Condens. Matter 22 264006 [10] Riedel D 2010 J. Phys.: Condens. Matter 22 264009 [11] Terada Y, Yoshida S, Takeuchi O and Shigekawa H 2010 J. Phys.: Condens. Matter 22 264008

  16. B-Target Room Tunnel Redesigned

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-08-25

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

  17. Tunneling anisotropic magnetoresistance: A spin-valve-like tunnel magnetoresistance using a single magnetic layer

    Czech Academy of Sciences Publication Activity Database

    Gould, C.; Rüster, C.; Jungwirth, Tomáš; Girgis, E.; Schott, G. M.; Giraud, R.; Brunner, K.; Schmidt, G.; Molenkamp, L. W.

    2004-01-01

    Roč. 93, č. 11 (2004), 117203/1-117203/4 ISSN 0031-9007 R&D Projects: GA ČR GA202/02/0912 Institutional research plan: CEZ:AV0Z1010914 Keywords : semiconductor spintronics * tunneling anisotropic magnetoresistance Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.218, year: 2004

  18. Resonant electron tunnelling assisted by charged domain walls in multiferroic tunnel junctions

    Science.gov (United States)

    Sanchez-Santolino, Gabriel; Tornos, Javier; Hernandez-Martin, David; Beltran, Juan I.; Munuera, Carmen; Cabero, Mariona; Perez-Muñoz, Ana; Ricote, Jesus; Mompean, Federico; Garcia-Hernandez, Mar; Sefrioui, Zouhair; Leon, Carlos; Pennycook, Steve J.; Muñoz, Maria Carmen; Varela, Maria; Santamaria, Jacobo

    2017-07-01

    The peculiar features of domain walls observed in ferroelectrics make them promising active elements for next-generation non-volatile memories, logic gates and energy-harvesting devices. Although extensive research activity has been devoted recently to making full use of this technological potential, concrete realizations of working nanodevices exploiting these functional properties are yet to be demonstrated. Here, we fabricate a multiferroic tunnel junction based on ferromagnetic La0.7Sr0.3MnO3 electrodes separated by an ultrathin ferroelectric BaTiO3 tunnel barrier, where a head-to-head domain wall is constrained. An electron gas stabilized by oxygen vacancies is confined within the domain wall, displaying discrete quantum-well energy levels. These states assist resonant electron tunnelling processes across the barrier, leading to strong quantum oscillations of the electrical conductance.

  19. Quantum dissipation, scattering and tunneling

    International Nuclear Information System (INIS)

    Eleuterio, S.M.; Vilela Mendes, R.

    1984-01-01

    A quantization technique for dissipative systems is used to discuss one dimensional problems including tunneling with dissipation, capture in dissipative potential wells and quantum coherence. (orig.)

  20. Thermovoltages in vacuum tunneling investigated by scanning tunneling microscopy

    OpenAIRE

    Hoffmann, D. H.; Rettenberger, Armin; Grand, Jean Yves; Läuger, K.; Leiderer, Paul; Dransfeld, Klaus; Möller, Rolf

    1995-01-01

    By heating the tunneling tip of a scanning tunneling microscope the thermoelectric properties of a variable vacuum barrier have been investigated. The lateral variation of the observed thermovoltage will be discussed for polycrystalline gold, stepped surfaces of silver, as well as for copper islands on silver.

  1. Reduced resistance drift in tunnel junctions using confined tunnel barriers

    Science.gov (United States)

    Barcikowski, Z. S.; Pomeroy, J. M.

    2017-11-01

    Metal-insulator-metal (MIM) tunnel junctions with the aluminum oxide tunnel barriers confined between cobalt electrodes exhibit less resistance drift over time than junctions that utilize a thick, unconfined aluminum electrode. The improved long time stability is attributed to better initial oxide quality achieved through confinement (use of a potential energy well for the oxygen) and plasma oxidation. In this work, Co/AlOx/Co and Co/Al/AlOx/Co tunnel junction aging is compared over a period of approximately 9 months using transport measurements and Wentzel-Kramers-Brillouin (WKB) based modelling. The Co/AlOx/Co (confined) tunnel junction resistance increased by (32 ± 6) % over 5400 h, while Co/Al/AlOx/Co (unconfined) tunnel junction resistance increased by (85 ± 23) % over 5200 h. Fit parameters for the tunnel barrier width and potential energy barriers were extracted using WKB transport modelling. These values change only a small amount in the confined Co/AlOx/Co tunnel junction but show a significant drift in the unconfined Co/AlOx/Co tunnel junction.

  2. Fundamental visual problems in tunnels : sumposium on tunnel lighting.

    NARCIS (Netherlands)

    Schreuder, D.A.

    2018-01-01

    Tunnels and underpasses are likely to play a greater part in our future road network. Daytime lighting for tunnel entrances represents a considerable proportion of their total running costs and it is important that the right solution should be found. Guidance is given in CIE Publication No. 26

  3. Engineers win award for Swiss tunnel

    CERN Multimedia

    2003-01-01

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

  4. Counter Tunnel Project

    Science.gov (United States)

    2014-03-01

    DSP-3000 fiber - optic gyro , MicroStrain 3DM-GX2 IMU, with USB and Ethernet connec- tors. Small enough to fit into all the tunnels that were explored...frame arms were sufficient for de- ployment of the RDC. Gigabit multi-mode fiber - optic communication and 48 VDC power were passed to the RDC through...with AcuAMP ACT050 current sensors. The control box monitoring all of the information, as well as the source of the 48 VDC and fiber - optic cable to

  5. Wind Tunnel for Aerodynamic Development Testing

    OpenAIRE

    E. T. L. Cöuras Ford; V. A. C. Vale; J. U. L. Mendes; F. A. Ribeiro

    2015-01-01

    The study of the aerodynamics related to the improvement in the acting of airplanes and automobiles with the objective of being reduced the effect of the attrition of the air on structures, providing larger speeds and smaller consumption of fuel. The application of the knowledge of the aerodynamics not more limits to the aeronautical and automobile industries. Therefore, this research aims to design and construction of a wind tunnel to perform aerodynamic analysis in bodi...

  6. Hawking temperature from tunnelling formalism

    OpenAIRE

    Mitra, P.

    2007-01-01

    It has recently been suggested that the attempt to understand Hawking radiation as tunnelling across black hole horizons produces a Hawking temperature double the standard value. It is explained here how one can obtain the standard value in the same tunnelling approach.

  7. 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 ...

  8. Carpal Tunnel Syndrome (For Kids)

    Science.gov (United States)

    ... First Aid & Safety Doctors & Hospitals Videos Recipes for Kids Kids site Sitio para niños How the Body Works ... Search English Español Carpal Tunnel Syndrome KidsHealth / For Kids / Carpal Tunnel Syndrome What's in this article? Where ...

  9. Item Response Theory with Covariates (IRT-C) : Assessing item recovery and differential item functioning for the three-parameter logistic model

    NARCIS (Netherlands)

    Tay, L.; Huang, Q.; Vermunt, J.K.

    2016-01-01

    In large-scale testing, the use of multigroup approaches is limited for assessing differential item functioning (DIF) across multiple variables as DIF is examined for each variable separately. In contrast, the item response theory with covariate (IRT-C) procedure can be used to examine DIF across

  10. Tunneling in thin MOS structures

    Science.gov (United States)

    Maserjian, J.

    1974-01-01

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

  11. Acoustic emission and ultrasonic-velocity methods used to characterise the excavation disturbance associated with deep tunnels in hard rock

    Science.gov (United States)

    Falls, Stephen D.; Young, R. Paul

    1998-04-01

    Acoustic emission (AE) and ultrasonic-velocity monitoring studies have been undertaken at both the Atomic Energy of Canada Limited (AECL) Underground Research Laboratory (URL) and at the Swedish Nuclear Fuel Waste Management Company (SKB) Hard Rock Laboratory (HRL). At both locations the excavations were tunnels in granitic material at approximately 420 m depth. However, the stress regime was more severe at the URL Mine-by tunnel site than the HRL ZEDEX tunnel. Different parts of the ZEDEX tunnel were created using different excavation techniques. Using AE and ultrasonic techniques to study these tunnels we have been able to examine the nature of the excavation-disturbed zone around the tunnel, as well as examining the effects of different stress regimes and excavation techniques. Studies were undertaken both during and after the Mine-by tunnel excavation and during excavation in the ZEDEX tunnel. AE monitoring in the wall of the Mine-by tunnel during excavation showed that some activity occurred in the sidewall regions, but the spatial density of AE hypocentres increased toward the regions in the floor and roof of the tunnel where breakout notches formed. This sidewall activity was clustered primarily within 0.5 m of the tunnel wall. AE monitoring in the floor of the tunnel showed that small numbers of AE continued to occur in the notch region in the floor of the tunnel over 2 years after excavation was completed. This activity became more acute as the rock was heated, imposing thermally induced stresses on the volume. Ultrasonic-velocity studies both in the floor and the wall of the tunnel showed that the velocity is strongly anisotropic with the direction of slowest velocity orthogonal to the tunnel surface. The velocity increased with distance into the rock from the tunnel surface. In the floor, this effect was seen up to 2 m from the tunnel surface. Most of the change occurred within the first 0.5 m from the tunnel perimeter. At the lower-stress HRL, most of

  12. Space Shuttle AFRSI OMS pod environment test using model 81-0 test fixture in the Ames Research Center 9x7-foot supersonic wind tunnel (OS-314A/B/C)

    Science.gov (United States)

    Collette, J. G. R.

    1984-01-01

    A test was conducted in the NASA/Ames Research Center 9x7-foot Supersonic Wind Tunnel to help resolve an anomaly that developed during the STS-6 orbiter flight wherein sections of the Advanced Flexible Reusable Surface Insulation (AFRSI) covering the OMS pods suffered some damage. A one-third scale two-dimensional shell structure model of an OMS pod cross-section was employed to support the test articles. These consisted of 15 AFRSI blanket panels form-fitted over the shell structures for exposure to simulated flight conditions. Of six baseline blankets, two were treated with special surface coatings. Two other panels were configured with AFRSI sections removed from the OV099 orbiter vehicle after the STS-6 flight. Seven additional specimens incorporated alternative designs and repairs. Following a series of surface pressure calibration runs, the specimens were exposed to simulated ascent and entry dynamic pressure profiles. Entry conditions included the use of a vortex generator to evaluate the effect of shed vortices on the AFRSI located in the area of concern.

  13. Does guessing matter? Differences between ability estimates from 2PL and 3PL IRT models in case of guessing

    Directory of Open Access Journals (Sweden)

    Tomasz Żółtak

    2015-09-01

    Full Text Available Modern approaches to measuring cognitive ability and testing knowledge frequently use multiple-choice items. These can be simply and rapidly scored without problems associated with rater subjectivity. Nevertheless, multiple-choice tests are often criticized owing to their vulnerability to guessing. In this paper the impact of guessing was examined using simulation. Ability estimates were obtained from the two IRT models commonly used for binary-scored items: the two-parameter logistic model and the three-parameter logistic model. The latter approach explicitly models guessing, whilst the former does not. Rather counter-intuitively, little difference was identified for point estimates of ability from the 2PLM and 3PLM. Nevertheless, it should be noted that difficulty and discrimination parameters are severely downwardly biased if a 2PLM is used to calibrate data generated by processes involving guessing. Estimated standard errors for ability estimates also differ considerably between these models.

  14. Hybrid High-Temperature-Superconductor–Semiconductor Tunnel Diode

    Directory of Open Access Journals (Sweden)

    Alex Hayat

    2012-12-01

    Full Text Available We report the demonstration of hybrid high-T_{c}-superconductor–semiconductor tunnel junctions, enabling new interdisciplinary directions in condensed matter research. The devices are fabricated by our newly developed mechanical-bonding technique, resulting in high-T_{c}-superconductor–semiconductor tunnel diodes. Tunneling-spectra characterization of the hybrid junctions of Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} combined with bulk GaAs, or a GaAs/AlGaAs quantum well, exhibits excess voltage and nonlinearity, similarly to spectra obtained in scanning-tunneling microscopy, and is in good agreement with theoretical predictions for a d-wave-superconductor–normal-material junction. Additional junctions are demonstrated using Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} combined with graphite or Bi_{2}Te_{3}. Our results pave the way for new methods in unconventional superconductivity studies, novel materials, and quantum technology applications.

  15. Sci—Thur AM: YIS - 03: irtGPUMCD: a new GPU-calculated dosimetry code for {sup 177}Lu-octreotate radionuclide therapy of neuroendocrine tumors

    Energy Technology Data Exchange (ETDEWEB)

    Montégiani, Jean-François; Gaudin, Émilie; Després, Philippe [Physics, Engineering Physics and Optics, Université Laval, Quebec City, QC (Canada); Jackson, Price A. [Molecular Imaging and Targeted Therapeutics, Peter MacCallum Cancer Centre, Melbourne, VIC (Australia); Beauregard, Jean-Mathieu [Radiology, Université Laval, Quebec City, QC (Canada)

    2014-08-15

    In peptide receptor radionuclide therapy (PRRT), huge inter-patient variability in absorbed radiation doses per administered activity mandates the utilization of individualized dosimetry to evaluate therapeutic efficacy and toxicity. We created a reliable GPU-calculated dosimetry code (irtGPUMCD) and assessed {sup 177}Lu-octreotate renal dosimetry in eight patients (4 cycles of approximately 7.4 GBq). irtGPUMCD was derived from a brachytherapy dosimetry code (bGPUMCD), which was adapted to {sup 177}Lu PRRT dosimetry. Serial quantitative single-photon emission computed tomography (SPECT) images were obtained from three SPECT/CT acquisitions performed at 4, 24 and 72 hours after {sup 177}Lu-octreotate administration, and registered with non-rigid deformation of CT volumes, to obtain {sup 177}Lu-octreotate 4D quantitative biodistribution. Local energy deposition from the β disintegrations was assumed. Using Monte Carlo gamma photon transportation, irtGPUMCD computed dose rate at each time point. Average kidney absorbed dose was obtained from 1-cm{sup 3} VOI dose rate samples on each cortex, subjected to a biexponential curve fit. Integration of the latter time-dose rate curve yielded the renal absorbed dose. The mean renal dose per administered activity was 0.48 ± 0.13 Gy/GBq (range: 0.30–0.71 Gy/GBq). Comparison to another PRRT dosimetry code (VRAK: Voxelized Registration and Kinetics) showed fair accordance with irtGPUMCD (11.4 ± 6.8 %, range: 3.3–26.2%). These results suggest the possibility to use the irtGPUMCD code in order to personalize administered activity in PRRT. This could allow improving clinical outcomes by maximizing per-cycle tumor doses, without exceeding the tolerable renal dose.

  16. Muck Problems in Subway Shield Tunneling in Sandy Cobble Stratum

    Directory of Open Access Journals (Sweden)

    Cui Kai

    2016-10-01

    Full Text Available Experiments aiming at the muck improvement for Chengdu’s subway shield tunneling in water-rich sandy cobble ground initially finds out the kinds and ratio of muck improver suitable for the this strata, and through the field application determines the reasonable ratio of muck improver for shield tunneling in sandy cobble ground, providing a reference to other muck improvement for shied tunneling in similar ground. And the earth pressure balanced shield is widely used in tunnel engineering, with its characteristics as wide adaptability, safe operation, fast driving speed, low environmental noise and low cost. Taking Chengdu Metro Line as the background, aiming at the difficulty faced by EPB shield tunneling in water-rich sandy cobble ground, and based on the explorations and researches of the predecessors and scholars, engineering and technical personnel, the present paper combines with engineering examples to make a systematic summary and research on key construction technology of EPB shield tunneling through sandy cobble ground from the aspects of EPB shield adaptability, , structure and transformation of cutter and helical unearthed wares, settlement control method, and muck improvement measures. It has certain reference value and guiding significance to the selection of shield machine and the reconstruction of shield machine in complex geological condition.

  17. Internal resistor of multi-functional tunnel barrier for selectivity and switching uniformity in resistive random access memory.

    Science.gov (United States)

    Lee, Sangheon; Woo, Jiyong; Lee, Daeseok; Cha, Euijun; Hwang, Hyunsang

    2014-01-01

    In this research, we analyzed the multi-functional role of a tunnel barrier that can be integrated in devices. This tunnel barrier, acting as an internal resistor, changes its resistance with applied bias. Therefore, the current flow in the devices can be controlled by a tunneling mechanism that modifies the tunnel barrier thickness for non-linearity and switching uniformity of devices. When a device is in a low-resistance state, the tunnel barrier controls the current behavior of the device because most of the bias is applied to the tunnel barrier owing to its higher resistance. Furthermore, the tunnel barrier induces uniform filament formation during set operation with the tunnel barrier controlling the current flow.

  18. The SlZRT1 Gene Encodes a Plasma Membrane-Located ZIP (Zrt-, Irt-Like Protein Transporter in the Ectomycorrhizal Fungus Suillus luteus

    Directory of Open Access Journals (Sweden)

    Laura Coninx

    2017-11-01

    Full Text Available Zinc (Zn is an essential micronutrient but may become toxic when present in excess. In Zn-contaminated environments, trees can be protected from Zn toxicity by their root-associated micro-organisms, in particular ectomycorrhizal fungi. The mechanisms of cellular Zn homeostasis in ectomycorrhizal fungi and their contribution to the host tree’s Zn status are however not yet fully understood. The aim of this study was to identify and characterize transporters involved in Zn uptake in the ectomycorrhizal fungus Suillus luteus, a cosmopolitan pine mycobiont. Zn uptake in fungi is known to be predominantly governed by members of the ZIP (Zrt/IrtT-like protein family of Zn transporters. Four ZIP transporter encoding genes were identified in the S. luteus genome. By in silico and phylogenetic analysis, one of these proteins, SlZRT1, was predicted to be a plasma membrane located Zn importer. Heterologous expression in yeast confirmed the predicted function and localization of the protein. A gene expression analysis via RT-qPCR was performed in S. luteus to establish whether SlZRT1 expression is affected by external Zn concentrations. SlZRT1 transcripts accumulated almost immediately, though transiently upon growth in the absence of Zn. Exposure to elevated concentrations of Zn resulted in a significant reduction of SlZRT1 transcripts within the first hour after initiation of the exposure. Altogether, the data support a role as cellular Zn importer for SlZRT1 and indicate a key role in cellular Zn uptake of S. luteus. Further research is needed to understand the eventual contribution of SlZRT1 to the Zn status of the host plant.

  19. An Assessment of the Scientific Merits of Action Research.

    Science.gov (United States)

    Susman, Gerald I.; Evered, Roger D.

    1978-01-01

    Action research is presented as a method for generating knowledge that corrects the deficiencies of positivist science. Action research is shown to base its scientific legitimacy in philosophical traditions that are different from those that legitimate positivist science. (Author/IRT)

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

    CERN Document Server

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

    2017-01-01

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

  1. Tunneling Ionization of Diatomic Molecules

    DEFF Research Database (Denmark)

    Svensmark, Jens Søren Sieg

    2016-01-01

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

  2. Role of Wind Tunnels in Aircraft Design

    Indian Academy of Sciences (India)

    large wind tunnels simulating the actual flight conditions as nearly as possible. Often, several wind tunnels ... wind tunnel tests can be 'scaled' to the actual velocity and actual body size using suitable scaling laws. A typical wind tunnel consists ofa test section ... tion and control positions. Some of this instrumentation like six.

  3. 78 FR 46117 - National Tunnel Inspection Standards

    Science.gov (United States)

    2013-07-30

    ... busiest vehicular tunnel in the world. The Fort McHenry Tunnel handles a daily traffic volume of more than... vehicular, transit, and rail tunnels in the New York City metropolitan area. Although it is still too early... congestion along alternative routes, and save users both dollars and fuel. If these tunnels were closed due...

  4. 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

  5. Results of a jet plume effects test on Rockwell International integrated space shuttle vehicle using a vehicle 5 configuration 0.02-scale model (88-OTS) in the 11 by 11 foot leg of the NASA/Ames Research Center unitary plan wind tunnel (IA19), volume 1

    Science.gov (United States)

    Nichols, M. E.

    1975-01-01

    Results are presented of jet plume effects test IA19 using a vehicle 5 configuration integrated space shuttle vehicle 0.02-scale model in the NASA/Ames Research Center 11 x 11-foot leg of the unitary plan wind tunnel. The jet plume power effects on the integrated vehicle static pressure distribution were determined along with elevon, main propulsion system nozzle, and solid rocket booster nozzle effectiveness and elevon hinge moments.

  6. ``Phantom'' Modes in Ab Initio Tunneling Calculations: Implications for Theoretical Materials Optimization, Tunneling, and Transport

    Science.gov (United States)

    Barabash, Sergey V.; Pramanik, Dipankar

    2015-03-01

    Development of low-leakage dielectrics for semiconductor industry, together with many other areas of academic and industrial research, increasingly rely upon ab initio tunneling and transport calculations. Complex band structure (CBS) is a powerful formalism to establish the nature of tunneling modes, providing both a deeper understanding and a guided optimization of materials, with practical applications ranging from screening candidate dielectrics for lowest ``ultimate leakage'' to identifying charge-neutrality levels and Fermi level pinning. We demonstrate that CBS is prone to a particular type of spurious ``phantom'' solution, previously deemed true but irrelevant because of a very fast decay. We demonstrate that (i) in complex materials, phantom modes may exhibit very slow decay (appearing as leading tunneling terms implying qualitative and huge quantitative errors), (ii) the phantom modes are spurious, (iii) unlike the pseudopotential ``ghost'' states, phantoms are an apparently unavoidable artifact of large numerical basis sets, (iv) a presumed increase in computational accuracy increases the number of phantoms, effectively corrupting the CBS results despite the higher accuracy achieved in resolving the true CBS modes and the real band structure, and (v) the phantom modes cannot be easily separated from the true CBS modes. We discuss implications for direct transport calculations. The strategy for dealing with the phantom states is discussed in the context of optimizing high-quality high- κ dielectric materials for decreased tunneling leakage.

  7. Origin of the water drained by the tunnel Graton

    International Nuclear Information System (INIS)

    Plata B, A.

    1992-12-01

    The research of the origin of the water drained by the Graton tunnel was attempted using isotope techniques. During the period of studies (April 1989-October 1992), four field work was executed to sample waters for chemistry, stable isotope and Tritium analysis, an to inject tracers and verify the possible infiltration from the Rimac and Blanco rivers to the tunnel. The results of the stable isotope analysis show that the water drained by the Graton tunnel comes from a basin around 300 meters above the average altitude of the basin where the Graton is located. The Tritium analysis show that the water is relatively modern. Using the model of total mixing, the residence times of the water drained at the km 0.5 and 2.5 are in the order to 45 years. The conductivities of the water of the tunnel is higher than the Rimac river ones because the influence of mine water. The chemical analysis of the water sampled at the downstream end of the tunnel, show that the conservative ions of the water kept almost constant during more than two years. The results of the work with artificial tracer show that there is no significant leakage from the Rimac and Blanco rivers to the Graton tunnel. So far, it can be concluded as a preliminary approach that the Graton tunnel drains relatively modern water originated in another basin. The hydrodynamics of the area of study seems to include a large storage on underground water in the system. The topography, geology and isotopic composition of the water samples, points to the upper Mantaro river basin as the possible source of part of the water drained by the Graton tunnel. (authors). 20 p. 2 figs., 7 ills., 4 tabs

  8. 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...

  9. Free Surface Water Tunnel (FSWT)

    Data.gov (United States)

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

  10. Scanning Tunneling Microscopy - image interpretation

    International Nuclear Information System (INIS)

    Maca, F.

    1998-01-01

    The basic ideas of image interpretation in Scanning Tunneling Microscopy are presented using simple quantum-mechanical models and supplied with examples of successful application. The importance is stressed of a correct interpretation of this brilliant experimental surface technique

  11. Flatback airfoil wind tunnel experiment.

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-04-01

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

  12. The effect of a twin tunnel on the propagation of ground-borne vibration from an underground railway

    Science.gov (United States)

    Kuo, K. A.; Hunt, H. E. M.; Hussein, M. F. M.

    2011-12-01

    Accurate predictions of ground-borne vibration levels in the vicinity of an underground railway are greatly sought after in modern urban centres. Yet the complexity involved in simulating the underground environment means that it is necessary to make simplifying assumptions about this system. One such commonly made assumption is to ignore the effects of neighbouring tunnels, despite the fact that many underground railway lines consist of twin-bored tunnels, one for the outbound direction and one for the inbound direction. This paper presents a unique model for two tunnels embedded in a homogeneous, elastic fullspace. Each of these tunnels is subject to both known, dynamic train forces and dynamic cavity forces. The net forces acting on the tunnels are written as the sum of those tractions acting on the invert of a single tunnel, and those tractions that represent the motion induced by the neighbouring tunnel. By apportioning the tractions in this way, the vibration response of a two-tunnel system is written as a linear combination of displacement fields produced by a single-tunnel system. Using Fourier decomposition, forces are partitioned into symmetric and antisymmetric modenumber components to minimise computation times. The significance of the interactions between two tunnels is quantified by calculating the insertion gains, in both the vertical and horizontal directions, that result from the existence of a second tunnel. The insertion-gain results are shown to be localised and highly dependent on frequency, tunnel orientation and tunnel thickness. At some locations, the magnitude of these insertion gains is greater than 20 dB. This demonstrates that a high degree of inaccuracy exists in any surface vibration prediction model that includes only one of the two tunnels. This novel two-tunnel solution represents a significant contribution to the existing body of research into vibration from underground railways, as it shows that the second tunnel has a significant

  13. CEBAF: Injector tunnel in action

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    On 28 October, a 100 kV DC electron beam was generated in the injector tunnel at the Continuous Electron Beam Accelerator Facility (CEBAF) being constructed at Newport News, Virginia. In this first tunnel operation, the beam was transported from the electron gun via the room-temperature section to the injector's first superconducting section (5 MeV). The gun and beam steering subsystems behaved as designed, under control from the main control centre

  14. Quantum resonances in physical tunneling

    International Nuclear Information System (INIS)

    Nieto, M.M.; Truax, D.R.

    1985-01-01

    It has recently been emphasized that the probability of quantum tunneling is a critical function of the shape of the potential. Applying this observation to physical systems, we point out that in principal information on potential surfaces can be obtained by studying tunneling rates. This is especially true in cases where only spectral data is known, since many potentials yield the same spectrum. 13 refs., 10 figs., 1 tab

  15. Charged Fermions Tunneling from a Rotating Charged Black Hole in 5-Dimensional Gauged Supergravity

    International Nuclear Information System (INIS)

    Li Huiling; Lin Rong; Wang Chuanyin

    2010-01-01

    Recent research shows that Hawking radiation from black hole horizon can be treated as a quantum tunneling process, and fermions tunneling method can successfully recover Hawking temperature. In this tunneling framework, choosing a set of appropriate matrices γ μ is an important technique for fermions tunneling method. In this paper, motivated by Kerner and Man's fermions tunneling method of 4 dimension black holes, we further improve the analysis to investigate Hawking tunneling radiation from a rotating charged black hole in 5-dimensional gauged supergravity by constructing a set of appropriate matrices γ μ for general covariant Dirac equation. Finally, the expected Hawking temperature of the black hole is correctly recovered, which takes the same form as that obtained by other methods. This method is universal, and can also be directly extend to the other different-type 5-dimensional charged black holes.

  16. Covariance Method of the Tunneling Radiation from High Dimensional Rotating Black Holes

    Science.gov (United States)

    Li, Hui-Ling; Han, Yi-Wen; Chen, Shuai-Ru; Ding, Cong

    2017-12-01

    In this paper, Angheben-Nadalini-Vanzo-Zerbini (ANVZ) covariance method is used to study the tunneling radiation from the Kerr-Gödel black hole and Myers-Perry black hole with two independent angular momentum. By solving the Hamilton-Jacobi equation and separating the variables, the radial motion equation of a tunneling particle is obtained. Using near horizon approximation and the distance of the proper pure space, we calculate the tunneling rate and the temperature of Hawking radiation. Thus, the method of ANVZ covariance is extended to the research of high dimensional black hole tunneling radiation.

  17. The time of discrete spectrum identical particles tunneling at their simultaneous passing over rectangular quantum barrier

    International Nuclear Information System (INIS)

    Martsenyuk, L.S.

    2010-01-01

    Research of influence of exchange interaction of identical particles for the time of their simultaneous tunneling through a rectangular quantum barrier is lead. The account of identity leads to necessity of symmetrisation of wave function owing to what in the formula describing interaction of two particles, arises an additional element. In result the parameters of tunneling, including time of tunneling change. Time of tunneling is calculated from the formula received in work from the size of exchange interaction of two particles simultaneously crossing a rectangular quantum barrier.

  18. Attoclock reveals natural coordinates of the laser-induced tunnelling current flow in atoms

    DEFF Research Database (Denmark)

    Pfeiffer, Adrian N.; Cirelli, Claudio; Smolarski, Mathias

    2012-01-01

    In the research area of strong-laser-field interactions and attosecond science1, tunnelling of an electron through the barrier formed by the electric field of the laser and the atomic potential is typically assumed to be the initial key process that triggers subsequent dynamics1, 2, 3. Here we use...... the attoclock technique4 to obtain experimental information about the electron tunnelling geometry (the natural coordinates of the tunnelling current flow) and exit point. We confirm vanishing tunnelling delay time, show the importance of the inclusion of Stark shifts5, 6 and report on multi-electron effects...

  19. Covariance Method of the Tunneling Radiation from High Dimensional Rotating Black Holes

    Science.gov (United States)

    Li, Hui-Ling; Han, Yi-Wen; Chen, Shuai-Ru; Ding, Cong

    2018-04-01

    In this paper, Angheben-Nadalini-Vanzo-Zerbini (ANVZ) covariance method is used to study the tunneling radiation from the Kerr-Gödel black hole and Myers-Perry black hole with two independent angular momentum. By solving the Hamilton-Jacobi equation and separating the variables, the radial motion equation of a tunneling particle is obtained. Using near horizon approximation and the distance of the proper pure space, we calculate the tunneling rate and the temperature of Hawking radiation. Thus, the method of ANVZ covariance is extended to the research of high dimensional black hole tunneling radiation.

  20. Conservation agriculture in high tunnels: soil health and profit enhancement

    Science.gov (United States)

    In 2013, through the USDA’s Evans-Allen capacity grant, the high tunnel became an on-farm research laboratory for conservation agriculture. Dr. Manuel R. Reyes, Professor and his research team from the North Carolina Agriculture and Technology State University (NCATSU), Greensboro, North Carolina (1...

  1. Static design of steel-concrete lining for traffic tunnels

    Science.gov (United States)

    Vojtasik, Karel; Mohyla, Marek; Hrubesova, Eva

    2017-09-01

    Article summarizes the results of research focused on the structural design of traffic tunnel linings that have been achieved in the framework of a research project TE01020168 that supports The Technology Agency of Czech Republic. This research aim is to find and develop a process for design structure parameters of tunnel linings. These are now mostly build up by a shotcrete technology. The shotcrete is commonly endorsed either with steel girders or steel fibres. Since the installation a lining structure is loaded while strength and deformational parameters of shotcrete start to rise till the setting time elapses. That’s reason why conventional approaches of reinforced concrete are not suitable. As well as there are other circumstances to step in shown in this article. Problem is solved by 3D analysis using numerical model that takes into account all the significant features of a tunnel lining construction process inclusive the interaction between lining structure with rock massive. Analysis output is a view into development of stress-strain state in respective construction parts of tunnel lining the whole structure around, including impact on stability of rock massive. The proposed method comprises all features involved in tunnel fabrication including geotechnics and construction technologies.

  2. Electronic noise of superconducting tunnel junction detectors

    International Nuclear Information System (INIS)

    Jochum, J.; Kraus, H.; Gutsche, M.; Kemmather, B.; Feilitzsch, F. v.; Moessbauer, R.L.

    1994-01-01

    The optimal signal to noise ratio for detectors based on superconducting tunnel junctions is calculated and compared for the cases of a detector consisting of one single tunnel junction, as well as of series and of parallel connections of such tunnel junctions. The influence of 1 / f noise and its dependence on the dynamical resistance of tunnel junctions is discussed quantitatively. A single tunnel junction yields the minimum equivalent noise charge. Such a tunnel junction exhibits the best signal to noise ratio if the signal charge is independent of detector size. In case, signal charge increases with detector size, a parallel or a series connection of tunnel junctions would provide the optimum signal to noise ratio. The equivalent noise charge and the respective signal to noise ratio are deduced as functions of tunnel junction parameters such as tunneling time, quasiparticle lifetime, etc. (orig.)

  3. Application of Neural Networks to Wind tunnel Data Response Surface Methods

    Science.gov (United States)

    Lo, Ching F.; Zhao, J. L.; DeLoach, Richard

    2000-01-01

    The integration of nonlinear neural network methods with conventional linear regression techniques is demonstrated for representative wind tunnel force balance data modeling. This work was motivated by a desire to formulate precision intervals for response surfaces produced by neural networks. Applications are demonstrated for representative wind tunnel data acquired at NASA Langley Research Center and the Arnold Engineering Development Center in Tullahoma, TN.

  4. Fermions Tunneling from Bardeen-Vaidya Black Hole via General Tortoise Coordinate Transformation

    Science.gov (United States)

    Kai, Lin; Shuzheng, Yang

    In this paper, we research on the scalar field particles and 1/2 spin fermions tunneling from the event horizon of Bardeen-Vaidya black hole by semiclassical method and general tortoise coordinate transformation, and obtain the Hawking temperature and tunneling rate near the event horizon.

  5. Theory of superconducting tunneling without the tunneling Hamiltonian

    International Nuclear Information System (INIS)

    Arnold, G.B.

    1987-01-01

    When a tunneling barrier is nearly transparent, the standard tunneling (or transfer) Hamiltonian approximation fails. The author describes the theory which is necessary for calculating the tunneling current in these cases, and illustrate it by comparing theory and experiment on superconductor/insulator/superconductor (SIS) junctions have ultra-thin tunnel barriers. This theory accurately explains the subgap structure which appears in the dynamical resistance of such SIS junctions, including many observed details which no previous theory has reproduced. The expression for the current through an SIS junction with an ultrathin barrier is given by I(t) = Re{Sigma/sub n/ J/sub n/ (omega/sub o/)e/sup in omega/o/sup t/} where omega/sub o/ = 2eV/h is the Josephson frequency, V is the bias voltage, and the J/sub n/ are voltage dependent coefficients, one for each positive or negative integer, n, and n=0. The relative sign of the terms involving cos(n omega/sub o/t) and sin(n omega/sub o/t) agrees with experiment, in contrast to previous theories of Josephson tunneling

  6. Design and Testing of an Educational Water Tunnel

    Science.gov (United States)

    Kosaraju, Srinivas

    2017-11-01

    A new water tunnel is designed and tested for educational and research purposes at Northern Arizona University. The university currently owns an educational wind tunnel with a test section of 12in X 12in X 24in. However, due to limited size of test section and range of Reynolds numbers, its application is currently limited to very few experiments. In an effort to expand the educational and research capabilities, a student team is tasked to design, build and test a water tunnel as a Capstone Senior Design project. The water tunnel is designed to have a test section of 8in X 8in X 36in. and be able to test up to Re = 50E3. Multiple numerical models are used to optimize the flow field inside the test section before building the physical apparatus. The water tunnel is designed to accommodate multiple experiments for drag and lift studies. The built-in die system can deliver up to three different colors to study the streamlines and vortex shedding from the surfaces. During the first phase, a low discharge pump is used to achieve Re = 4E3 to test laminar flows. In the second phase, a high discharge pump will be used to achieve targeted Re = 50E3 to study turbulent flows.

  7. Metal-binding thermodynamics of the histidine-rich sequence from the metal-transport protein IRT1 of Arabidopsis thaliana.

    Science.gov (United States)

    Grossoehme, Nicholas E; Akilesh, Shreeram; Guerinot, Mary Lou; Wilcox, Dean E

    2006-10-16

    The widespread ZIP family of transmembrane metal-transporting proteins is characterized by a large intracellular loop that contains a histidine-rich sequence whose biological role is unknown. To provide a chemical basis for this role, we prepared and studied a peptide corresponding to this sequence from the first iron-regulated transporter (IRT1) of Arabidopsis thaliana, which transports Fe2+ as well as Mn2+, Co2+, Zn2+, and Cd2+. Isothermal titration calorimetry (ITC) measurements, which required novel experiments and data analysis, and supporting spectroscopic methods were used to quantify IRT1's metal-binding affinity and associated thermodynamics. The peptide, PHGHGHGHGP, binds metal ions with 1:1 stoichiometry and stabilities that are consistent with the Irving-Williams series. Comparison of the metal-binding thermodynamics of the peptide with those of trien provides new insight about enthalpic and entropic contributions to the stability of the metal-peptide complex. Although Fe2+ and other IRT1-transported metal ions do not bind very tightly, this His-rich sequence has a very high entropy-driven affinity for Fe3+, which may have biological significance.

  8. 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

  9. Reconstructing the Roman Site “Aquis Querquennis” (Bande, Spain from GPR, T-LiDAR and IRT Data Fusion

    Directory of Open Access Journals (Sweden)

    Iván Puente

    2018-03-01

    Full Text Available This work presents the three-dimensional (3D reconstruction of one of the most important archaeological sites in Galicia: “Aquis Querquennis” (Bande, Spain using in-situ non-invasive ground-penetrating radar (GPR and Terrestrial Light Detection and Ranging (T-LiDAR techniques, complemented with infrared thermography. T-LiDAR is used for the recording of the 3D surface of this particular case and provides high resolution 3D digital models. GPR data processing is performed through the novel software tool “toGPRi”, developed by the authors, which allows the creation of a 3D model of the sub-surface and the subsequent XY images or time-slices at different depths. All these products are georeferenced, in such a way that the GPR orthoimages can be combined with the orthoimages from the T-LiDAR for a complete interpretation of the site. In this way, the GPR technique allows for the detection of the structures of the barracks that are buried, and their distribution is completed with the structure measured by the T-LiDAR on the surface. In addition, the detection of buried elements made possible the identification and labelling of the structures of the surface and their uses. These structures are additionally inspected with infrared thermography (IRT to determine their conservation condition and distinguish between original and subsequent constructions.

  10. 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

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

    Science.gov (United States)

    Zahari, M.; Dol, S. S.

    2015-04-01

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

  12. Superconducting tunnel-junction refrigerator

    International Nuclear Information System (INIS)

    Melton, R.G.; Paterson, J.L.; Kaplan, S.B.

    1980-01-01

    The dc current through an S 1 -S 2 tunnel junction, with Δ 2 greater than Δ 1 , when biased with eV 1 +Δ 2 , will lower the energy in S 1 . This energy reduction will be shared by the phonons and electrons. This device is shown to be analogous to a thermoelectric refrigerator with an effective Peltier coefficient π* approx. Δ 1 /e. Tunneling calculations yield the cooling power P/sub c/, the electrical power P/sub e/ supplied by the bias supply, and the cooling efficiency eta=P/sub c//P/sub e/. The maximum cooling power is obtained for eV= +- (Δ 2 -Δ 1 ) and t 1 =T 1 /T/sub c/1 approx. 0.9. Estimates are made of the temperature difference T 2 -T 1 achievable in Al-Pb and Sn-Pb junctions with an Al 2 O 3 tunneling barrier. The performance of this device is shown to yield a maximum cooling efficiency eta approx. = Δ 1 /(Δ 2 -Δ 1 ) which can be compared with that available in an ideal Carnot refrigerator of eta=T 1 /(T 2 -T 1 ). The development of a useful tunnel-junction refrigerator requires a tunneling barrier with an effective thermal conductance per unit area several orders of magnitude less than that provided by the A1 2 O 3 barrier in the Al-Pb and Sn-Pb systems

  13. TunnelVision: LHC Tunnel Photogrammetry System for Structural Monitoring

    CERN Document Server

    Fallas, William

    2014-01-01

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

  14. A neutronic feasibility study for LEU conversion of the IR-8 research reactor

    International Nuclear Information System (INIS)

    Deen, J.R.; Hanan, N.A.; Matos, J.E.; Egorenkov, P.M.; Nasonov, V.A.

    1998-01-01

    Equilibrium fuel cycle comparisons for the IR-8 research reactor were made for HEU (90%), HEU (36%), and LEU (19.75%) fuel assembly (FA) designs using three dimensional multi-group diffusion theory models benchmarked to detailed Monte Carlo models of the reactor. Comparisons were made of changes in reactivity, cycle length, average 235 U discharge burnup, thermal neutron flux, and control rod worths for the 90% and 36% enriched IRT-3M fuel assembly and the 19.75% enriched IRT-4M fuel assembly with the same fuel management strategy. The results of these comparisons showed that a uranium density of 3.5 g/cm 3 in the fuel meat would be required in the LEU IRT-4M fuel assembly to match the cycle length of the HEU (90%) IRT-3M FA and an LEU density of 3.7 g/cm 3 is needed to match the cycle length of the HEU (36%) IRT-3M FA. (author)

  15. Probing electronic interactions using electron tunneling

    Indian Academy of Sciences (India)

    pratap

    The scanning tunneling microscope: Principle d. eI. Tunneling Current. Topography by tracking current: Constant height mode. Tracking the height: Constant current mode. NbSe. 2 single crystal. (Grown by P. Shirage and A. Thamizhavel) ...

  16. Proposal for Marshmallow Tunnel Stemming Study

    Energy Technology Data Exchange (ETDEWEB)

    1962-01-01

    Discussion of findings after the shot in the tunnel and instructions for a deeper drilling below the tunnel using radiation probes to help define the cavity shape and documentary photography of the findings.

  17. Quantum mechanical tunneling in chemical physics

    CERN Document Server

    Nakamura, Hiroki

    2016-01-01

    Quantum mechanical tunneling plays important roles in a wide range of natural sciences, from nuclear and solid-state physics to proton transfer and chemical reactions in chemistry and biology. Responding to the need for further understanding of multidimensional tunneling, the authors have recently developed practical methods that can be applied to multidimensional systems. Quantum Mechanical Tunneling in Chemical Physics presents basic theories, as well as original ones developed by the authors. It also provides methodologies and numerical applications to real molecular systems. The book offers information so readers can understand the basic concepts and dynamics of multidimensional tunneling phenomena and use the described methods for various molecular spectroscopy and chemical dynamics problems. The text focuses on three tunneling phenomena: (1) energy splitting, or tunneling splitting, in symmetric double well potential, (2) decay of metastable state through tunneling, and (3) tunneling effects in chemical...

  18. Spin tunnelling in mesoscopic systems

    Science.gov (United States)

    Garg, Anupam

    2001-02-01

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

  19. Tunneling field effect transistor technology

    CERN Document Server

    Chan, Mansun

    2016-01-01

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

  20. Watertightness of concrete tunnel structures

    OpenAIRE

    Glerum, A.

    1982-01-01

    The Netherlands are situated in the delta. of the rivers Rhine, Meuse and Scheldt. Therefore the ground mainly consists.of sediments, such as sand, clay and silt. In certain regions peat layers of varying thickness are found. The high permeability of some of these materials and the fact that the groundwater table is generally only 1 m below ground level, make an adequate watertightness one of the main features of tunnel engineering in the Netherlands. Tunnels in Holland are both of the immers...

  1. Relaxing cross-national measurement invariance using a hierarchical IRT model

    NARCIS (Netherlands)

    de Jong, Martijn G.; Steenkamp, Jan-Benedict E.M.; Fox, Gerardus J.A.

    2007-01-01

    With the growing interest of consumer researchers to test measures and theories in an international context, the cross-national invariance of measurement instruments has become an important issue. At least two issues still need to be addressed. First, the ordinal nature of the rating scale is

  2. The Mechanical Impact of Aerodynamic Stall on Tunnel Ventilation Fans

    Directory of Open Access Journals (Sweden)

    A. G. Sheard

    2012-01-01

    Full Text Available This paper describes work aimed at establishing the ability of a tunnel ventilation fan to operate without risk of mechanical failure in the event of aerodynamic stall. The research establishes the aerodynamic characteristics of a typical tunnel ventilation fan when operated in both stable and stalled aerodynamic conditions, with and without an anti-stall stabilisation ring, with and without a “nonstalling” blade angle and at full, half, and one quarter design speed. It also measures the fan’s peak stress, thus facilitating an analysis of the implications of the experimental results for mechanical design methodology. The paper concludes by presenting three different strategies for tunnel ventilation fan selection in applications where the selected fan will most likely stall. The first strategy selects a fan with a low-blade angle that is nonstalling. The second strategy selects a fan with a high-pressure developing capability. The third strategy selects a fan with a fitted stabilisation ring. Tunnel ventilation system designers each have their favoured fan selection strategy. However, all three strategies can produce system designs within which a tunnel ventilation fan performs reliably in-service. The paper considers the advantages and disadvantages of each selection strategy and considered the strengths and weaknesses of each.

  3. Quasi-bound states, resonance tunnelling, and tunnelling times ...

    Indian Academy of Sciences (India)

    scattering and decay of unstable nuclei via alpha decay, proton emission etc. as evident from refs [14–19]. A detailed procedure exists for the study of such states in ...... for the case of transmission across equispaced multiple barriers generating well-separated QB states. 3. The variation of total tunnelling time Tq shows ...

  4. Tunneling in high-K isomeric decays

    CERN Document Server

    Shizuma, T; Shimizu, Y R

    2002-01-01

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

  5. Polarization-dependent tunneling of light in gradient optics

    Czech Academy of Sciences Publication Activity Database

    Shvartsburg, A. B.; Kuzmiak, Vladimír; Petite, G.

    2007-01-01

    Roč. 76, č. 1 (2007), 016603.1-01663.11 ISSN 1539-3755 R&D Projects: GA MŠk(CZ) OC P11.001 Institutional research plan: CEZ:AV0Z20670512 Keywords : wave propagation * tunnelling Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.483, year: 2007

  6. Wind tunnel tests of a free yawing downwind wind turbine

    NARCIS (Netherlands)

    Verelst, D.R.S.; Larsen, T.J.; Van Wingerden, J.W.

    2014-01-01

    This research paper presents preliminary results on a behavioural study of a free yawing downwind wind turbine. A series of wind tunnel tests was performed at the TU Delft Open Jet Facility with a three bladed downwind wind turbine and a rotor radius of 0.8 meters. The setup includes an off the

  7. 9x15 Low Speed Wind Tunnel Acoustic Improvements

    Science.gov (United States)

    Stark, David; Stephens, David

    2016-01-01

    The 9- by 15-Foot Low Speed Wind Tunnel (9x15 LSWT) at NASA Glenn Research Center was built in 1969 in the return leg of the 8- by 6-Foot Supersonic Wind Tunnel (8x6 SWT). The 8x6 SWT was completed in 1949 and acoustically treated to mitigate community noise issues in 1950. This treatment included the addition of a large muffler downstream of the 8x6 SWT test section and diffuser. The 9x15 LSWT was designed for performance testing of VSTOL aircraft models, but with the addition of the current acoustic treatment in 1986 the tunnel has been used principally for acoustic and performance testing of aircraft propulsions systems. The present document describes an anticipated acoustic upgrade to be completed in 2017.

  8. Advanced Metrology for Characterization of Magnetic Tunnel Junctions

    DEFF Research Database (Denmark)

    Kjær, Daniel

    solutions to take products to the next node and the field of memory technology is no exception. Over the past decade research and development in a novel, non-volatile memory type known as MRAM has intensified, and commercial MRAM devices are now available. MRAM holds an extremely favorable position...... as it is believed to have the potential of becoming a truly universal memory solution dominant within all fields of memory application. A decade ago the company CAPRES A/S introduced the so-called CIPTech, which is a metrology tool utilizing micro four-point probes (M4PPs) and a method known as current in......-plane tunneling (CIPT) for characterization of magnetic tunnel junctions (MTJs), which constitutes the key component not only in MRAM but also the read-heads of modern hard disk drives. MTJs are described by their tunnel magnetoresistance (TMR), which is the relative difference of the resistance area products (RA...

  9. Structural integrity of wind tunnel wooden fan blades

    Science.gov (United States)

    Young, Clarence P., Jr.; Wingate, Robert T.; Rooker, James R.; Mort, Kenneth W.; Zager, Harold E.

    1991-01-01

    Information is presented which was compiled by the NASA Inter-Center Committee on Structural Integrity of Wooden Fan Blades and is intended for use as a guide in design, fabrication, evaluation, and assurance of fan systems using wooden blades. A risk assessment approach for existing NASA wind tunnels with wooden fan blades is provided. Also, state of the art information is provided for wooden fan blade design, drive system considerations, inspection and monitoring methods, and fan blade repair. Proposed research and development activities are discussed, and recommendations are provided which are aimed at future wooden fan blade design activities and safely maintaining existing NASA wind tunnel fan blades. Information is presented that will be of value to wooden fan blade designers, fabricators, inspectors, and wind tunnel operations personnel.

  10. Materials Handling for Urban Tunneling in Rock

    Science.gov (United States)

    1979-01-01

    An examination of prior forecasts of tunnel construction provides an estimate of 2.4 million feet of rock tunnel to be constructed during the 1976-2000 period. Tunnel projects for the near term (1980+) and far term (1990+) periods are defined for stu...

  11. 75 FR 42643 - National Tunnel Inspection Standards

    Science.gov (United States)

    2010-07-22

    ... title 23 Federal funds that are located on public roads and tunnels on Federal-aid highways. The agency... the fatal July 2006 suspended ceiling collapse in the Central Artery Tunnel in Boston, [[Page 42644... located on public roads and tunnels on Federal-aid highways. The NTIS are needed to ensure that all...

  12. Oliver E. Buckley Prize Talk: Spin polarized tunneling and tunnel magnetoresistance -- Learning from the past and moving forward

    Science.gov (United States)

    Moodera, Jagadeesh

    2009-03-01

    Electron tunneling phenomenon has contributed enormously to our understanding of various branches of physics over the years. The technique of spin polarized tunneling (SPT), sensing the spin polarization of tunneling electrons using a superconducting spin detector, discovered by Meservey and Tedrow in the early seventies has been successfully utilized over the years to understand many aspects of magnetism and superconductivity. Electrical spin injection/detection in a semiconductor is strongly believed to succeed through such an approach. The successful observation of a large change in tunnel current in magnetic tunnel junctions (MTJ) in the mid nineties has brought extreme activity in this field -- both from fundamental study as well as extensive application in mind (as sensors, nonvolatile memory devices, logic elements etc). From the early history of this field that led to the discovery of room temperature TMR effect to the observation of many novel phenomena to the exciting recent work on spin filtering, spin transport in semiconductors to toggling of the superconducting state with spin current will be highlighted and reviewed. Work done in collaboration with Drs. Meservey and Tedrow, PhD students, postdoctorals, as well as high school students and undergraduates. NSF, ONR, DARPA and KIST-MIT project funds supported the research over the years.

  13. Bias dependence of tunnel magnetoresistance in spin filtering tunnel junctions: Experiment and theory

    Science.gov (United States)

    Lüders, U.; Bibes, M.; Fusil, S.; Bouzehouane, K.; Jacquet, E.; Sommers, C. B.; Contour, J.-P.; Bobo, J.-F.; Barthélémy, A.; Fert, A.; Levy, P. M.

    2007-10-01

    A spin filter is a type of magnetic tunnel junction in which only one of the electrodes is magnetic and the insulating barrier is ferro- or ferrimagnetic. We report on spin-dependent transport measurements and their theoretical analysis in epitaxial spin filters integrating a tunnel barrier of the high-Curie-temperature ferrimagnetic spinel NiFe2O4 , with half-metallic La2/3Sr1/3MnO3 and Au electrodes. A positive tunnel magnetoresonance of up to ˜50% is obtained at low temperature, which we find decreases with bias voltage. In view of these experimental results, we propose a theoretical treatment of the transport properties of spin filters with epitaxial magnetic barriers, based on an elliptical variation of the decay rates within the spin-dependent gaps in analogy with what was calculated for nonmagnetic barrier materials such as MgO or SrTiO3 . Whereas the spin filtering efficiency for zero bias is of one sign, we show that this can easily change with bias; the degree of change hinges on the energy variation of the majority and minority spin decay rates of the transmission across the barrier. We point out some shortcomings of approaches based on models in which the transmission is related to spin-dependent barrier heights, and some implications for future experimental and theoretical research on spin filters.

  14. Nano-ADEPT Aeroloads Wind Tunnel Test

    Science.gov (United States)

    Smith, Brandon; Yount, Bryan; Kruger, Carl; Brivkalns, Chad; Makino, Alberto; Cassell, Alan; Zarchi, Kerry; McDaniel, Ryan; Ross, James; Wercinski, Paul; hide

    2016-01-01

    A wind tunnel test of the Adaptable Deployable Entry and Placement Technology (ADEPT) was conducted in April 2015 at the US Army's 7 by10 Foot Wind Tunnel located at NASA Ames Research Center. Key geometric features of the fabric test article were a 0.7 meter deployed base diameter, a 70 degree half-angle forebody cone angle, eight ribs, and a nose-to-base radius ratio of 0.7. The primary objective of this wind tunnel test was to obtain static deflected shape and pressure distributions while varying pretension at dynamic pressures and angles of attack relevant to entry conditions at Earth, Mars, and Venus. Other objectives included obtaining aerodynamic force and moment data and determining the presence and magnitude of any dynamic aeroelastic behavior (buzz/flutter) in the fabric trailing edge. All instrumentation systems worked as planned and a rich data set was obtained. This paper describes the test articles, instrumentation systems, data products, and test results. Four notable conclusions are drawn. First, test data support adopting a pre-tension lower bound of 10 foot pounds per inch for Nano-ADEPT mission applications in order to minimize the impact of static deflection. Second, test results indicate that the fabric conditioning process needs to be reevaluated. Third, no flutter/buzz of the fabric was observed for any test condition and should also not occur at hypersonic speeds. Fourth, translating one of the gores caused ADEPT to generate lift without the need for a center of gravity offset. At hypersonic speeds, the lift generated by actuating ADEPT gores could be used for vehicle control.

  15. Contrastwaarnemingen in tunnels : een meetmethode.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1994-01-01

    The entrance to a long road tunnel can present itself to an approaching driver as a 'black hole' during the daytime, with no possibility for observing any details. In contrast to traditional symmetrical lighting, counter beam lighting aims the light in the opposite direction to incoming traffic.

  16. Travelling inside the SPS tunnel

    CERN Multimedia

    1974-01-01

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

  17. Apparent tunneling in chemical reactions

    DEFF Research Database (Denmark)

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

    2000-01-01

    A necessary condition for tunneling in a chemical reaction is that the probability of crossing a barrier is non-zero, when the energy of the reactants is below the potential energy of the barrier. Due to the non-classical nature (i.e, momentum uncertainty) of vibrational states this is, however...

  18. A Seamless Ubiquitous Telehealthcare Tunnel

    Directory of Open Access Journals (Sweden)

    Sao-Jie Chen

    2013-08-01

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

  19. Spin tunnelling in mesoscopic systems

    Indian Academy of Sciences (India)

    Spin tunnelling; spin path integrals; discrete phase integral method; diabolical points. ... technologies. Our purpose in this article is rather different. The molecular systems have total spin of the order of 10, and magnetocrystalline anisotropies of few tens of Kelvin ...... The point С' is of this new type, and here it may be said to.

  20. Rotational tunnelling spectroscopy with neutrons

    International Nuclear Information System (INIS)

    Carlile, C.J.; Prager, M.

    1993-04-01

    Neutron tunnelling spectroscopy has been a very fruitful field for almost two decades and is still expanding into new areas, both experimentally and theoretically. The development of the topic is reviewed from the theoretical point of view, highlighting new approaches, and selected examples of more recent experimental work are presented. A brief discussion of instrument performance and experimental requirements is given. (author)

  1. Installation in the SPS tunnel

    CERN Multimedia

    1974-01-01

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

  2. Time tunnels meet warped passages

    CERN Multimedia

    Kushner, David

    2006-01-01

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

  3. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

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

  4. International Review Team (IRT) Safety Case Recommendations for the Yucca Mountain Total System Performance Assessment (TSPA) Supporting the Site Recommendation

    International Nuclear Information System (INIS)

    Van Luik, Abraham E.

    2004-01-01

    The session started with Abe Van Luik (IGSC Chair, US-DOE-YM, USA) who presented the feedback of the international peer review of the US-DOE Yucca Mountain TSPA (Total System Performance Assessment) supporting the successful designation of the site by the Congress and the President of the U.S. In particular, he listed key implications of the IRT (International Review team) recommendations on the forthcoming US-DOE documentation of its case for safety to be submitted to the regulator, the U.S. Nuclear Regulatory Commission, mainly: - The documentation submitted to the licensing authority should address technical aspects and compliance with regulatory criteria. - That documentation should reflect sound science and good engineering practice; it should present detailed and rigorous modelling. - In addition, it should present both quantitative and qualitative arguments, make a statement on why there can be confidence in the face of uncertainty, acknowledge remaining issues and provide the strategy to resolve them. - Demonstrating understanding is as important as demonstrating compliance. - There is a need to provide a clear explanation of the case made to the regulator for more general audiences to complement the large amount of technical documents that will be produced. The US-DOE response to these recommendations for the License Application, which is under preparation, is that the recommendations will be implemented to the maximum extent possible. In subsequent discussion, with respect to the License Application, it was acknowledged that detailed guidance from the U.S. regulator was very useful, and guidance of this type would be generally useful. At the current time, the words 'safety case' are not mentioned in U.S. regulations, but if one reads both the regulation and guidance documents it becomes evident that all aspects of a safety case need to be provided in the License Application and its accompanying documents

  5. Evaluation of the Hospital Anxiety and Depression Scale (HADS) in screening stroke patients for symptoms: Item Response Theory (IRT) analysis.

    Science.gov (United States)

    Ayis, Salma A; Ayerbe, Luis; Ashworth, Mark; DA Wolfe, Charles

    2018-03-01

    Variations have been reported in the number of underlying constructs and choice of thresholds that determine caseness of anxiety and /or depression using the Hospital Anxiety and Depression scale (HADS). This study examined the properties of each item of HADS as perceived by stroke patients, and assessed the information these items convey about anxiety and depression between 3 months to 5 years after stroke. The study included 1443 stroke patients from the South London Stroke Register (SLSR). The dimensionality of HADS was examined using factor analysis methods, and items' properties up to 5 years after stroke were tested using Item Response Theory (IRT) methods, including graded response models (GRMs). The presence of two dimensions of HADS (anxiety and depression) for stroke patients was confirmed. Items that accurately inferred about the severity of anxiety and depression, and offered good discrimination of caseness were identified as "I can laugh and see the funny side of things" (Q4) and "I get sudden feelings of panic" (Q13), discrimination 2.44 (se = 0.26), and 3.34 (se = 0.35), respectively. Items that shared properties, hence replicate inference were: "I get a sort of frightened feeling as if something awful is about to happen" (Q3), "I get a sort of frightened feeling like butterflies in my stomach" (Q6), and "Worrying thoughts go through my mind" (Q9). Item properties were maintained over time. Approximately 20% of patients were lost to follow up. A more concise selection of items based on their properties, would provide a precise approach for screening patients and for an optimal allocation of patients into clinical trials. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Analytical Estimation of the Central Reflector Impact on Thermal Neutron Flux Density in Research Reactors

    Directory of Open Access Journals (Sweden)

    Gvozdyakov Dmitry V.

    2015-01-01

    Full Text Available In this research was shown an analytical assessment of the impact of the central reflector as an example of spherical reactor in one-group approximation. From the external reflector introduced an effective border that simplifies the mathematical problem of critical task. The validation of the research is done just for one of the IRT-T reactor conditions.

  7. Fiber coupled ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

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

    1997-01-01

    We report on a scanning tunneling microscope with a photoconductive gate in the tunneling current circuit. The tunneling tip is attached to a coplanar transmission line with an integrated photoconductive switch. The switch is illuminated through a fiber which is rigidly attached to the switch...... waveguide. The measurements show that the probe works as a transient voltage detector in contact and a capacitively coupled transient field detector in tunneling mode. We do not measure the transient voltage change in the ohmic tunneling current. In this sense, the spatial resolution for propagating...

  8. Tunnel widening in anterior cruciate ligament reconstruction

    DEFF Research Database (Denmark)

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

    1999-01-01

    We report a prospective series evaluating the incidence and degree of tunnel widening in a well-matched series of patients receiving a hamstring or patella tendon graft for anterior cruciate ligament (ACL) deficiency. We correlated tunnel widening with clinical factors, knee scores, KT-1000...... in the degree of tunnel widening between the two groups. The mean increase in femoral tunnel area in the hamstring group was 100.4% compared with a decrease of 25% in the patella tendon group (P = hamstring group was 73.9% compared with a decrease of 2.......1% in the patella tendon group (P = hamstring group. Tunnel widening does not correlate with instability...

  9. A comparison of two estimation algorithms for Samejima's continuous IRT model.

    Science.gov (United States)

    Zopluoglu, Cengiz

    2013-03-01

    This study compares two algorithms, as implemented in two different computer softwares, that have appeared in the literature for estimating item parameters of Samejima's continuous response model (CRM) in a simulation environment. In addition to the simulation study, a real-data illustration is provided, and CRM is used as a potential psychometric tool for analyzing measurement outcomes in the context of curriculum-based measurement (CBM) in the field of education. The results indicate that a simplified expectation-maximization (EM) algorithm is as effective and efficient as the traditional EM algorithm for estimating the CRM item parameters. The results also show promise for using this psychometric model to analyze CBM outcomes, although more research is needed in order to recommend CRM as a standard practice in the CBM context.

  10. Computational Analysis of the Transonic Dynamics Tunnel Using FUN3D

    Energy Technology Data Exchange (ETDEWEB)

    Chwalowski, Pawel; Quon, Eliot; Brynildsen, Scott E.

    2016-01-04

    This paper presents results from an explanatory two-year effort of applying Computational Fluid Dynamics (CFD) to analyze the empty-tunnel flow in the NASA Langley Research Center Transonic Dynamics Tunnel (TDT). The TDT is a continuous-flow, closed circuit, 16- x 16-foot slotted-test-section wind tunnel, with capabilities to use air or heavy gas as a working fluid. In this study, experimental data acquired in the empty tunnel using the R-134a test medium was used to calibrate the computational data. The experimental calibration data includes wall pressures, boundary-layer profiles, and the tunnel centerline Mach number profiles. Subsonic and supersonic flow regimes were considered, focusing on Mach 0.5, 0.7 and Mach 1.1 in the TDT test section. This study discusses the computational domain, boundary conditions, and initial conditions selected in the resulting steady-state analyses using NASA's FUN3D CFD software.

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

    Science.gov (United States)

    Petersen, Jakob; Pollak, Eli

    2017-09-07

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

  12. Automated Boundary Conditions for Wind Tunnel Simulations

    Science.gov (United States)

    Carlson, Jan-Renee

    2018-01-01

    Computational fluid dynamic (CFD) simulations of models tested in wind tunnels require a high level of fidelity and accuracy particularly for the purposes of CFD validation efforts. Considerable effort is required to ensure the proper characterization of both the physical geometry of the wind tunnel and recreating the correct flow conditions inside the wind tunnel. The typical trial-and-error effort used for determining the boundary condition values for a particular tunnel configuration are time and computer resource intensive. This paper describes a method for calculating and updating the back pressure boundary condition in wind tunnel simulations by using a proportional-integral-derivative controller. The controller methodology and equations are discussed, and simulations using the controller to set a tunnel Mach number in the NASA Langley 14- by 22-Foot Subsonic Tunnel are demonstrated.

  13. Tunneling recombination processes in PbWO.sub.4./sub. crystals

    Czech Academy of Sciences Publication Activity Database

    Fabeni, P.; Kiisk, V.; Krasnikov, A.; Nikl, Martin; Pazzi, G.P.; Sildos, I.; Zazubovich, S.

    2007-01-01

    Roč. 4, č. 3 (2007), s. 918-921 ISSN 1862-6351 Institutional research plan: CEZ:AV0Z10100521 Keywords : tunneling * excitation spectra * decay kinetics * scintillators Subject RIV: BM - Solid Matter Physics ; Magnetism

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

    Science.gov (United States)

    Suarez, Carlos J.; Malcolm, Gerald N.

    1994-01-01

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

  15. SMART Rotor Development and Wind-Tunnel Test

    Science.gov (United States)

    Lau, Benton H.; Straub, Friedrich; Anand, V. R.; Birchette, Terry

    2009-01-01

    Boeing and a team from Air Force, NASA, Army, Massachusetts Institute of Technology, University of California at Los Angeles, and University of Maryland have successfully completed a wind-tunnel test of the smart material actuated rotor technology (SMART) rotor in the 40- by 80-foot wind-tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center, figure 1. The SMART rotor is a full-scale, five-bladed bearingless MD 900 helicopter rotor modified with a piezoelectric-actuated trailing-edge flap on each blade. The development effort included design, fabrication, and component testing of the rotor blades, the trailing-edge flaps, the piezoelectric actuators, the switching power amplifiers, the actuator control system, and the data/power system. Development of the smart rotor culminated in a whirl-tower hover test which demonstrated the functionality, robustness, and required authority of the active flap system. The eleven-week wind tunnel test program evaluated the forward flight characteristics of the active-flap rotor, gathered data to validate state-of-the-art codes for rotor noise analysis, and quantified the effects of open- and closed-loop active-flap control on rotor loads, noise, and performance. The test demonstrated on-blade smart material control of flaps on a full-scale rotor for the first time in a wind tunnel. The effectiveness and the reliability of the flap actuation system were successfully demonstrated in more than 60 hours of wind-tunnel testing. The data acquired and lessons learned will be instrumental in maturing this technology and transitioning it into production. The development effort, test hardware, wind-tunnel test program, and test results will be presented in the full paper.

  16. Resonant tunnel magnetoresistance in a double magnetic tunnel junction

    KAUST Repository

    Useinov, Arthur

    2011-08-09

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

  17. The Third Quantization: To Tunnel or Not to Tunnel?

    Directory of Open Access Journals (Sweden)

    Mariam Bouhmadi-López

    2018-02-01

    Full Text Available Within the framework of the third quantization, we consider the possibility that an initially recollapsing baby universe can enter a stage of near de Sitter inflation by tunnelling through a Euclidean wormhole that connects the recollapsing and inflationary geometries. We present the solutions for the evolution of the scale factor in the Lorentzian and Euclidean regions as well as the probability that the baby universe indeed crosses the wormhole when it reaches its maximum size.

  18. Airloads Correlation of the UH-60A Rotor inside the 40- by 80-Foot Wind Tunnel

    OpenAIRE

    I-Chung Chang; Thomas R. Norman; Ethan A. Romander

    2014-01-01

    The presented research validates the capability of a loosely coupled computational fluid dynamics (CFD) and comprehensive rotorcraft analysis (CRA) code to calculate the flowfield around a rotor and test stand mounted inside a wind tunnel. The CFD/CRA predictions for the Full-Scale UH-60A Airloads Rotor inside the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel at NASA Ames Research Center are compared with the latest measured airloads and performance data. The stud...

  19. Physical model for recognition tunneling

    International Nuclear Information System (INIS)

    Krstić, Predrag; Ashcroft, Brian; Lindsay, Stuart

    2015-01-01

    Recognition tunneling (RT) identifies target molecules trapped between tunneling electrodes functionalized with recognition molecules that serve as specific chemical linkages between the metal electrodes and the trapped target molecule. Possible applications include single molecule DNA and protein sequencing. This paper addresses several fundamental aspects of RT by multiscale theory, applying both all-atom and coarse-grained DNA models: (1) we show that the magnitude of the observed currents are consistent with the results of non-equilibrium Green’s function calculations carried out on a solvated all-atom model. (2) Brownian fluctuations in hydrogen bond-lengths lead to current spikes that are similar to what is observed experimentally. (3) The frequency characteristics of these fluctuations can be used to identify the trapped molecules with a machine-learning algorithm, giving a theoretical underpinning to this new method of identifying single molecule signals. (paper)

  20. Underwater piercing of a tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Solvik, O.

    1984-11-01

    Norwegian consultants and contractors have been confronted with the task of blasting a final penetrating passage that will open the way for the water in a reservoir to flow through the hydropower turbines. Norway has almost certainly led in this area because of its special topographical and geological conditions. The glacial activities have created a number of natural and very deep lakes forming cheap reservoirs. Piercings at depths up to about 100 m have been performed. Problems tend to increase with depth, but unsuccessful penetration can occur at any depth. Secondary effects to consider include the danger of slides when the water level is lowered, wave erosion along the lowered new shoreline, erosion at all streams and rivers flowing into the lake and groundwater erosion in the newly exposed dry shoreline. Methods of penetration can be roughly divided into two categories: penetration against the open tunnel shaft (open system); and penetration against the closed tunnel shaft (closed system). 6 figures.

  1. Single-contact tunneling thermometry

    Science.gov (United States)

    Maksymovych, Petro

    2016-02-23

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

  2. Tunneling magnetoresistance in Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    2016-11-09

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

  3. Tunneling of a coupled system

    International Nuclear Information System (INIS)

    Avishai, Y.

    1985-01-01

    We consider tunneling through a potential barrier V(x) in the presence of a coupling term W(x,y). Let H(y) be the internal Hamiltonian associated with the coordinate y and let E 0 (x) be the ground state energy of the operator H(x;y) = H(y) + W(x,y) in which x is a parameter. Our result for the tunneling probability (in the WKB approximation) is P = exp(2i ∫ k 0 (x)dx) where, at energy E, k 0 (x) = [E-E 0 (x)-V(x)]sup(1/2)/(h/2π) is the local wave number in the presence of coupling. (orig.)

  4. Spin tunneling in magnetic molecules

    Science.gov (United States)

    Kececioglu, Ersin

    In this thesis, we will focus on spin tunneling in a family of systems called magnetic molecules such as Fe8 and Mn12. This is comparatively new, in relation to other tunneling problems. Many issues are not completely solved and/or understood yet. The magnetic molecule Fe 8 has been observed to have a rich pattern of degeneracies in its magnetic spectrum. We focus on these degeneracies from several points of view. We start with the simplest anisotropy Hamiltonian to describe the Fe 8 molecule and extend our discussion to include higher order anisotropy terms. We give analytical expressions as much as we can, for the degeneracies in the semi-classical limit in both cases. We reintroduce jump instantons to the instanton formalism. Finally, we discuss the effect of the environment on the molecule. Our results, for all different models and techniques, agree well with both experimental and numerical results.

  5. Seismic scanning tunneling macroscope - Theory

    KAUST Repository

    Schuster, Gerard T.

    2012-09-01

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

  6. Digging the CNGS decay tunnel

    CERN Multimedia

    Patrice Loiez

    2002-01-01

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

  7. Dissipative Effect and Tunneling Time

    Directory of Open Access Journals (Sweden)

    Samyadeb Bhattacharya

    2011-01-01

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

  8. Tunnel Cost-Estimating Methods.

    Science.gov (United States)

    1981-10-01

    Mayo, R. S., Barrett, J. E., and Jenny, R. J. 1976. "Tunneling: The State of the Industry ," Report No. DOT-TSC-OST-76-29, Department of Transporta...as a... C *YPAUS CHECK FOR HOTAL INPUT 1F(ELNJL.GT.-1s.Eag.AND.ELNPR.GT.-Ig.E29) GO TO St *OSS3@ *I00 WRITEILO,1031) NTSEG.NREACH 04540 MI ISTOP-i

  9. Diagnosis of Carpal Tunnel Syndrome

    OpenAIRE

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

    2009-01-01

    This clinical practice guideline was created to improve patient care by outlining the appropriate information-gathering and decision-making processes involved in managing the diagnosis of carpal tunnel syndrome. The methods used to develop this clinical practice guideline were designed to combat bias, enhance transparency, and promote reproducibility. The guideline’s recommendations are as follows: The physician should obtain an accurate patient history. The physician should perform a physica...

  10. Autonomous Robotic Inspection in Tunnels

    Science.gov (United States)

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

    2016-06-01

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

  11. Diagnosis of Carpal Tunnel Syndrome

    Science.gov (United States)

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

    2016-01-01

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

  12. Tunneling beyond the Fermilab site

    International Nuclear Information System (INIS)

    Baker, S.; Elwyn, A.; Lach, J.; Read, A.

    1983-01-01

    An accelerator that crosses the Fermilab site boundary must have a minimum effect on the surrounding environment and the people residing in the area. Unobstructed public access should be allowed above the ring except in relatively few areas such as the injection, dump, and experimental regions. The accelerator should be a benign and unobtrusive neighbor not only when it is completed but also in the construction period. For these reasons underground tunneling for all or most of the ring seems attractive. In this note we look into some questions raised by tunneling beyond the Fermilab site. Most of our discussion is of general applicability. However, we will use as examples two specific ring configurations. The examples have not been optimized from the point of view of physics output or accelerator technology but are just specific examples which allow us to study questions of tunneling. One is a ring of 5 km radius (5 TeV) tangent to the Tevatron and entirely east of the Fox River and fed by a beam from the Tevatron which crosses under the river. We assume that each of these machines will have 100 beam fills per year and we scale the maximum intensities with the accelerator radii. Thus we assume that there will be 1.0 E14 protons in each beam of the 20 TeV machine and 2.5 E13 for the 5 TeV machine

  13. Quantum Tunneling Affects Engine Performance.

    Science.gov (United States)

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

    2013-06-20

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

  14. 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

  15. 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

  16. Chaos regularization of quantum tunneling rates

    International Nuclear Information System (INIS)

    Pecora, Louis M.; Wu Dongho; Lee, Hoshik; Antonsen, Thomas; Lee, Ming-Jer; Ott, Edward

    2011-01-01

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

  17. Check-Standard Testing Across Multiple Transonic Wind Tunnels with the Modern Design of Experiments

    Science.gov (United States)

    Deloach, Richard

    2012-01-01

    This paper reports the result of an analysis of wind tunnel data acquired in support of the Facility Analysis Verification & Operational Reliability (FAVOR) project. The analysis uses methods referred to collectively at Langley Research Center as the Modern Design of Experiments (MDOE). These methods quantify the total variance in a sample of wind tunnel data and partition it into explained and unexplained components. The unexplained component is further partitioned in random and systematic components. This analysis was performed on data acquired in similar wind tunnel tests executed in four different U.S. transonic facilities. The measurement environment of each facility was quantified and compared.

  18. 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.

  19. CFD and experimental data of closed-loop wind tunnel flow

    Directory of Open Access Journals (Sweden)

    John Kaiser Calautit

    2016-06-01

    Full Text Available The data presented in this article were the basis for the study reported in the research articles entitled ‘A validated design methodology for a closed loop subsonic wind tunnel’ (Calautit et al., 2014 [1], which presented a systematic investigation into the design, simulation and analysis of flow parameters in a wind tunnel using Computational Fluid Dynamics (CFD. The authors evaluated the accuracy of replicating the flow characteristics for which the wind tunnel was designed using numerical simulation. Here, we detail the numerical and experimental set-up for the analysis of the closed-loop subsonic wind tunnel with an empty test section.

  20. RITD – Wind tunnel testing

    Science.gov (United States)

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

    2015-04-01

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

  1. Tunneling anisotropic magnetoresistance in Co/AIOx/Al tunnel junctions with fcc Co (111) electrodes

    NARCIS (Netherlands)

    Wang, Kai; Tran, T. Lan Ahn; Brinks, Peter; Brinks, P.; Sanderink, Johannes G.M.; Bolhuis, Thijs; van der Wiel, Wilfred Gerard; de Jong, Machiel Pieter

    2013-01-01

    Tunneling anisotropic magnetoresistance (TAMR) has been characterized in junctions comprised of face-centered cubic (fcc) Co (111) ferromagnetic electrodes grown epitaxially on sapphire substrates, amorphous AlOx tunnel barriers, and nonmagnetic Al counterelectrodes. Large TAMR ratios have been

  2. Ski jumping takeoff in a wind tunnel with skis.

    Science.gov (United States)

    Virmavirta, Mikko; Kivekäs, Juha; Komi, Paavo

    2011-11-01

    The effect of skis on the force-time characteristics of the simulated ski jumping takeoff was examined in a wind tunnel. Takeoff forces were recorded with a force plate installed under the tunnel floor. Signals from the front and rear parts of the force plate were collected separately to examine the anteroposterior balance of the jumpers during the takeoff. Two ski jumpers performed simulated takeoffs, first without skis in nonwind conditions and in various wind conditions. Thereafter, the same experiments were repeated with skis. The jumpers were able to perform very natural takeoff actions (similar to the actual takeoff) with skis in wind tunnel. According to the subjective feeling of the jumpers, the simulated ski jumping takeoff with skis was even easier to perform than the earlier trials without skis. Skis did not much influence the force levels produced during the takeoff but they still changed the force distribution under the feet. Contribution of the forces produced under the rear part of the feet was emphasized probably because the strong dorsiflexion is needed for lifting the skis to the proper flight position. The results presented in this experiment emphasize that research on ski jumping takeoff can be advanced by using wind tunnels.

  3. Electronic states in tunneling semiconductor superlattices: Technical progress report for the period September 15, 1987-September 14, 1988

    International Nuclear Information System (INIS)

    Ulloa, S.E.

    1988-01-01

    This research project funded by DOE has concentrated in the systematic study of the effects of a gate voltage on the electronic structure of a tunneling superlattice system. The effects of strong magnetic fields and other various parameters on energy levels of tunneling superlattices have been investigated

  4. PUREX Storage Tunnels dangerous waste permit application

    International Nuclear Information System (INIS)

    1991-12-01

    This report is part of a dangerous waste permit application for the storage of wastes from the Purex process at Hanford. Appendices are presented on the following: construction drawings; HSW-5638, specifications for disposal facility for failed equipment, Project CA-1513-A; HWS-8262, specification for Purex equipment disposal, Project CGC 964; storage tunnel checklist; classification of residual tank heels in Purex storage tunnels; emergency plan for Purex facility; training course descriptions; and the Purex storage tunnels engineering study

  5. Climatic wind tunnel for wind engineering tasks

    Czech Academy of Sciences Publication Activity Database

    Kuznetsov, Sergeii; Pospíšil, Stanislav; Král, Radomil

    2015-01-01

    Roč. 112, 2-B (2015), s. 303-316 ISSN 1897-628X R&D Projects: GA ČR(CZ) GA14-12892S Keywords : climatic tunnel * wind tunnel * atmospheric boundary layer * flow resistance * wind tunnel contraction Subject RIV: JM - Building Engineering https://suw.biblos.pk.edu.pl/resources/i5/i6/i6/i7/i6/r56676/KuznetsovS_ClimaticWind.pdf

  6. Quantum tunneling and field electron emission theories

    CERN Document Server

    Liang, Shi-Dong

    2013-01-01

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

  7. Resonant tunneling of electrons in quantum wires

    International Nuclear Information System (INIS)

    Krive, I.V.; Shekhter, R.I.; Jonson, M.; Krive, I.V.

    2010-01-01

    We considered resonant electron tunneling in various nanostructures including single wall carbon nanotubes, molecular transistors and quantum wires formed in two-dimensional electron gas. The review starts with a textbook description of resonant tunneling of noninteracting electrons through a double-barrier structure. The effects of electron-electron interaction in sequential and resonant electron tunneling are studied by using Luttinger liquid model of electron transport in quantum wires. The experimental aspects of the problem (fabrication of quantum wires and transport measurements) are also considered. The influence of vibrational and electromechanical effects on resonant electron tunneling in molecular transistors is discussed.

  8. Femtosecond tunneling response of surface plasmon polaritons

    DEFF Research Database (Denmark)

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

    1998-01-01

    We obtain femtosecond (200 fs) time resolution using a scanning tunneling microscope on surface plasmon polaritons (SPPs) generated by two 100 fs laser beams in total internal reflection geometry. The tunneling gap dependence of the signal clearly indicates the tunneling origin of the signal...... and suggests that nanometer spatial resolution can be obtained together with femtosecond temporal resolution. This fast response, in contrast to the picosecond decay time of SPPs revealed by differential reflectivity measurements, can be attributed to a coherent superposition of SPPs rectified at the tunneling...... junction. (C) 1998 American Institute of Physics. [S0003-6951(98)02223-2]....

  9. PUREX Storage Tunnels dangerous waste permit application

    International Nuclear Information System (INIS)

    1991-12-01

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

  10. Probing spin-polarized tunneling at high bias and temperature with a magnetic tunnel transistor

    NARCIS (Netherlands)

    Park, B.G.; Banerjee, T.; Min, B.C.; Sanderink, Johannes G.M.; Lodder, J.C.; Jansen, R.

    2005-01-01

    The magnetic tunnel transistor (MTT) is a three terminal hybrid device that consists of a tunnel emitter, a ferromagnetic (FM) base, and a semiconductor collector. In the MTT with a FM emitter and a single FM base, spin-polarized hot electrons are injected into the base by tunneling. After

  11. Resonant tunneling via spin-polarized barrier states in a magnetic tunnel junction

    NARCIS (Netherlands)

    Jansen, R.; Lodder, J.C.

    2000-01-01

    Resonant tunneling through states in the barrier of a magnetic tunnel junction has been analyzed theoretically for the case of a spin-polarized density of barrier states. It is shown that for highly spin-polarized barrier states, the magnetoresistance due to resonant tunneling is enhanced compared

  12. 28 November 2013 - N. N. Kudryavtsev, Russian Rector of the Moscow Institute of Physics and Technology signing an Agreement and the Guest Book with CERN Director-General R. Heuer; visiting the ATLAS cavern with ATLAS Deputy Spokesperson B. Heinemann and visiting the LHC tunnel at Point 1 with AGH University of Science and Technology A. Erokhin. M. Savino, Physics Department, Joint Institute for Nuclear Research also present.

    CERN Multimedia

    Jean-Claude Gadmer

    2013-01-01

    28 November 2013 - N. N. Kudryavtsev, Russian Rector of the Moscow Institute of Physics and Technology signing an Agreement and the Guest Book with CERN Director-General R. Heuer; visiting the ATLAS cavern with ATLAS Deputy Spokesperson B. Heinemann and visiting the LHC tunnel at Point 1 with AGH University of Science and Technology A. Erokhin. M. Savino, Physics Department, Joint Institute for Nuclear Research also present.

  13. 10 September 2013 - Italian Minister for Economic Development F. Zanonato visiting the ATLAS cavern with Collaboration Spokesperson D. Charlton and Italian scientists F. Gianotti and A. Di Ciaccio; signing the guest book with CERN Director-General R. Heuer and Director for Research and Scientific Computing S. Bertolucci; in the LHC tunnel with S. Bertolucci, Technology Deputy Department Head L. Rossi and Engineering Department Head R. Saban; visiting CMS cavern with Scientists G. Rolandi and P. Checchia.

    CERN Multimedia

    Jean-Claude Gadmer

    2013-01-01

    10 September 2013 - Italian Minister for Economic Development F. Zanonato visiting the ATLAS cavern with Collaboration Spokesperson D. Charlton and Italian scientists F. Gianotti and A. Di Ciaccio; signing the guest book with CERN Director-General R. Heuer and Director for Research and Scientific Computing S. Bertolucci; in the LHC tunnel with S. Bertolucci, Technology Deputy Department Head L. Rossi and Engineering Department Head R. Saban; visiting CMS cavern with Scientists G. Rolandi and P. Checchia.

  14. From epitaxial growth of ferrite thin films to spin-polarized tunnelling

    International Nuclear Information System (INIS)

    Moussy, Jean-Baptiste

    2013-01-01

    This paper presents a review of the research which is focused on ferrite thin films for spintronics. First, I will describe the potential of ferrite layers for the generation of spin-polarized currents. In the second step, the structural and chemical properties of epitaxial thin films and ferrite-based tunnel junctions will be presented. Particular attention will be given to ferrite systems grown by oxygen-assisted molecular beam epitaxy. The analysis of the structure and chemistry close to the interfaces, a key-point for understanding the spin-polarized tunnelling measurements, will be detailed. In the third part, the magnetic and magneto-transport properties of magnetite (Fe 3 O 4 ) thin films as a function of structural defects such as the antiphase boundaries will be explained. The spin-polarization measurements (spin-resolved photoemission, tunnel magnetoresistance) on this oxide predicted to be half-metallic will be discussed. Fourth, the potential of magnetic tunnel barriers, such as CoFe 2 O 4 , NiFe 2 O 4 or MnFe 2 O 4 , whose insulating behaviour and the high Curie temperatures make it exciting candidates for spin filtering at room temperature will be described. Spin-polarized tunnelling experiments, involving either Meservey–Tedrow or tunnel magnetoresistance measurements, will reveal significant spin-polarizations of the tunnelling current at low temperatures but also at room temperatures. Finally, I will mention a few perspectives with ferrite-based heterostructures. (topical review)

  15. Tuning the tunneling probability by mechanical stress in Schottky barrier based reconfigurable nanowire transistors

    Science.gov (United States)

    Baldauf, Tim; Heinzig, André; Trommer, Jens; Mikolajick, Thomas; Weber, Walter Michael

    2017-02-01

    Mechanical stress is an established and important tool of the semiconductor industry to improve the performance of modern transistors. It is well understood for the enhancement of carrier mobility but rather unexplored for the control of the tunneling probability for injection dominated research devices based on tunneling phenomena, such as tunnel FETs, resonant tunnel FETs and reconfigurable Schottky FETs. In this work, the effect of stress on the tunneling probability and overall transistor characteristics is studied by three-dimensional device simulations in the example of reconfigurable silicon nanowire Schottky barrier transistors using two independently gated Schottky junctions. To this end, four different stress sources are investigated. The effects of mechanical stress on the average effective tunneling mass and on the multi-valley band structure applying the deformation potential theory are being considered. The transfer characteristics of strained transistors in n- and p-configuration and corresponding charge carrier tunneling are analyzed with respect to the current ratio between electron and hole conduction. For the implementation of these devices into complementary circuits, the mandatory current ratio of unity can be achieved by appropriate mechanical stress either by nanowire oxidation or the application of a stressed top layer.

  16. Coupled numerical simulation of fire in tunnel

    Science.gov (United States)

    Pesavento, F.; Pachera, M.; Schrefler, B. A.; Gawin, D.; Witek, A.

    2018-01-01

    In this work, a coupling strategy for the analysis of a tunnel under fire is presented. This strategy consists in a "one-way" coupling between a tool considering the computational fluid dynamics and radiation with a model treating concrete as a multiphase porous material exposed to high temperature. This global approach allows for taking into account in a realistic manner the behavior of the "system tunnel", composed of the fluid and the solid domain (i.e. the concrete structures), from the fire onset, its development and propagation to the response of the structure. The thermal loads as well as the moisture exchange between the structure surface and the environment are calculated by means of computational fluid dynamics. These set of data are passed in an automatic way to the numerical tool implementing a model based on Multiphase Porous Media Mechanics. Thanks to this strategy the structural verification is no longer based on the standard fire curves commonly used in the engineering practice, but it is directly related to a realistic fire scenario. To show the capability of this strategy some numerical simulations of a fire in the Brenner Base Tunnel, under construction between Italy and Austria, is presented. The numerical simulations show the effects of a more realistic distribution of the thermal loads with respect to the ones obtained by using the standard fire curves. Moreover, it is possible to highlight how the localized thermal load generates a non-uniform pressure rise in the material, which results in an increase of the structure stress state and of the spalling risk. Spalling is likely the most dangerous collapse mechanism for a concrete structure. This coupling approach still represents a "one way" strategy, i.e. realized without considering explicitly the mass and energy exchange from the structure to the fluid through the interface. This results in an approximation, but from physical point of view the current form of the solid-fluid coupling is

  17. Proceedings - Workshop on Materials Handling for Tunnel Construction

    Science.gov (United States)

    1977-08-01

    With the anticipated increases in tunnel construction in the next decade, greater demands will be made on transportation sytems to remove tunnel muck at rates consistent with tunnel excavation rates. This workshop discussed and noted that conventiona...

  18. Tunnelling from Goedel black holes

    International Nuclear Information System (INIS)

    Kerner, Ryan; Mann, R. B.

    2007-01-01

    We consider the spacetime structure of Kerr-Goedel black holes, analyzing their parameter space in detail. We apply the tunnelling method to compute their temperature and compare the results to previous calculations obtained via other methods. We claim that it is not possible to have the closed timelike curve (CTC) horizon in between the two black hole horizons and include a discussion of issues that occur when the radius of the CTC horizon is smaller than the radius of both black hole horizons

  19. Quantum tunnelling in condensed media

    CERN Document Server

    Kagan, Yu

    1992-01-01

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

  20. A Historical Evaluation of the U16a Tunnel, Nevada National Security Site, Nye County, Nevada Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Roberrt C. [Desert Research Inst. (DRI), Reno, NV (United States); Drollinger, Harold [Desert Research Inst. (DRI), Reno, NV (United States)

    2013-06-01

    This report presents a historical evaluation of the U16a Tunnel on the Nevada National Security Site in southern Nevada. The work was conducted by the Desert Research Institute at the request of the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office and the U.S. Department of Defense, Defense Threat Reduction Agency. The U16a Tunnel was used for underground nuclear weapons effects tests in Shoshone Mountain in Area 16 of the Nevada National Security Site. Six nuclear tests were conducted in the U16a Tunnel from 1962 to 1971. These tests are Marshmallow, Gum Drop, Double Play, Ming Vase, Diamond Dust, and Diamond Mine. The U.S. Department of Defense Threat Reduction Agency, with participation from Lawrence Livermore National Laboratory and Las Alamos National Laboratory, sponsored the tests. Fifteen high explosives tests were also conducted at the tunnel. Two were calibration tests during nuclear testing and the remaining were U.S. Department of Defense, Defense Threat Reduction Agency tunnel defeat tests. The U16a Tunnel complex is on the top and slopes of Shoshone Mountain, encompassing an area of approximately 16.7 hectares (41.1 acres). Major modifications to the landscape are a result of three principal activities, road construction and maintenance, mining activities related to development of the tunnel complex, and site preparation for activities related to testing. Forty-seven cultural features were recorded at the portal and on the slopes of Shoshone Mountain. At the portal area, features relate to the mining, construction, testing, and general every day operational support activities within the tunnel. These include concrete foundations for buildings, equipment pads, and rail lines. Features on the slopes above the tunnel relate to tunnel ventilation, borehole drilling, and data recording. Feature types include soil-covered bunkers, concrete foundations, instrument cable holes, drill holes, and ventilation shafts. The U16

  1. A Historical Evaluation of the U16a Tunnel, Nevada National Security Site, Nye County, Nevada Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Robert C. [Desert Research Inst. (DRI), Reno, NV (United States); Drollinger, Harold [Desert Research Inst. (DRI), Reno, NV (United States); Bullard, Thomas F. [Desert Research Inst. (DRI), Reno, NV (United States); Ashbaugh, Laurence J. [Desert Research Inst. (DRI), Reno, NV (United States); Griffin, Wayne R. [Desert Research Inst. (DRI), Reno, NV (United States)

    2013-01-01

    This report presents a historical evaluation of the U16a Tunnel on the Nevada National Security Site in southern Nevada. The work was conducted by the Desert Research Institute at the request of the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office and the U.S. Department of Defense, Defense Threat Reduction Agency. The U16a Tunnel was used for underground nuclear weapons effects tests in Shoshone Mountain in Area 16 of the Nevada National Security Site. Six nuclear tests were conducted in the U16a Tunnel from 1962 to 1971. These tests are Marshmallow, Gum Drop, Double Play, Ming Vase, Diamond Dust, and Diamond Mine. The U.S. Department of Defense Threat Reduction Agency, with participation from Lawrence Livermore National Laboratory and Las Alamos National Laboratory, sponsored the tests. Fifteen high explosives tests were also conducted at the tunnel. Two were calibration tests during nuclear testing and the remaining were U.S. Department of Defense, Defense Threat Reduction Agency tunnel defeat tests. The U16a Tunnel complex is on the top and slopes of Shoshone Mountain, encompassing an area of approximately 16.7 hectares (41.1 acres). Major modifications to the landscape are a result of three principal activities, road construction and maintenance, mining activities related to development of the tunnel complex, and site preparation for activities related to testing. Forty-seven cultural features were recorded at the portal and on the slopes of Shoshone Mountain. At the portal area, features relate to the mining, construction, testing, and general every day operational support activities within the tunnel. These include concrete foundations for buildings, equipment pads, and rail lines. Features on the slopes above the tunnel relate to tunnel ventilation, borehole drilling, and data recording. Feature types include soil-covered bunkers, concrete foundations, instrument cable holes, drill holes, and ventilation shafts. The U16

  2. Velocity Measurement Systems for a Low-speed Wind Tunnel

    Science.gov (United States)

    2015-04-29

    SECURITY CLASSIFICATION OF: Funds were provided by the ARO for the purchase of TSI hot-wire anemometer equipment and a Dantec particle- image...Velocity Measurement Systems for a Low-speed Wind Tunnel Report Title Funds were provided by the ARO for the purchase of TSI hot-wire anemometer equipment...Funds were provided by the Army Research Office for the purchase of TSI hot-wire anemometer equipment and a Dantec particle-image velocimetry system

  3. Risk identification and allocation of the utility tunnel PPP project

    Science.gov (United States)

    Mao, Yihua; Zhang, Yaoyao

    2017-05-01

    Based on the literature study of utility tunnel, 60 project risk factors are identified through expert interviews and classified into macro level risks, meso level risks and micro level risks according to the risk level. At the same time, we study the risk-sharing mechanism, then adopt the control force principle, the cognition principle and the profit principle to allocate risk, and put forward the pertinent risk countermeasure in order to provide the reference for the future practice and theory research.

  4. Importance of complex band structure and resonant states for tunneling

    Czech Academy of Sciences Publication Activity Database

    Dederichs, P. H.; Mavropoulos, Ph.; Wunnicke, O.; Papanikolaou, N.; Bellini, V.; Zeller, R.; Drchal, Václav; Kudrnovský, Josef

    2002-01-01

    Roč. 240, - (2002), s. 108-113 ISSN 0304-8853 R&D Projects: GA AV ČR IAA1010829; GA ČR GA202/00/0122; GA MŠk OC P5.30 Grant - others:TSR(XX) 01398 Institutional research plan: CEZ:AV0Z1010914 Keywords : magnetoresistance * tunneling * band structure * interface effects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.046, year: 2002

  5. Background Pressure Profiles for Sonic Boom Vehicle Testing in the NASA Glenn 8- by 6-Foot Supersonic Wind Tunnel

    Science.gov (United States)

    Castner, Raymond; Shaw, Stephen; Adamson, Eric; Simerly, Stephanie

    2013-01-01

    In an effort to identify test facilities that offer sonic boom measurement capabilities, an exploratory test program was initiated using wind tunnels at NASA research centers. The subject of this report is the sonic boom pressure rail data collected in the Glenn Research Center 8- by 6-Foot Supersonic Wind Tunnel. The purpose is to summarize the lessons learned based on the test activity, specifically relating to collecting sonic boom data which has a large amount of spatial pressure variation. The wind tunnel background pressure profiles are presented as well as data which demonstrated how both wind tunnel Mach number and model support-strut position affected the wind tunnel background pressure profile. Techniques were developed to mitigate these effects and are presented.

  6. Computational Wind Tunnel: A Design Tool for Rotorcraft, Phase I

    Data.gov (United States)

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

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

    Data.gov (United States)

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

  8. Road tunnels safety according to European legislation

    Directory of Open Access Journals (Sweden)

    Fedor KÁLLAY

    2008-01-01

    Full Text Available The article deals with safety of European road tunnels in accordance with actual European legislation. Standards and recommendations of European Commission, PIARC and other professional bodies of the European Union define minimal technological requirements for equipment and operation of the tunnels in scope of Trans-European Road Network.

  9. Spin tunneling and manipulation in nanostructures.

    Science.gov (United States)

    Sherman, E Ya; Ban, Yue; Gulyaev, L V; Khomitsky, D V

    2012-09-01

    The results for joint effects of tunneling and spin-orbit coupling on spin dynamics in nanostructures are presented for systems with discrete and continuous spectra. We demonstrate that tunneling plays the crucial role in the spin dynamics and the abilities of spin manipulation by external electric field. This result can be important for design of nanostructures-based spintronics devices.

  10. Tunneling of electrons through semiconductor superlattices

    Indian Academy of Sciences (India)

    Unknown

    Tunneling of electrons through semiconductor superlattices. C L ROY. Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721 302, India. Abstract. The purpose of the present paper is to report a study of tunneling of electrons through semicon- ductor superlattices (SSL); specially, we have ...

  11. Role of Wind Tunnels in Aircraft Design

    Indian Academy of Sciences (India)

    Wind tunnel is an aerodynamic test facility. It is mostly used to study flow patterns around bodies and measure aerodynamic forces on them. The bodies (called models) are usually scaled down but geometrically similar versions of bodies of interest like an airplane or an automobile. The results from wind tunnel tests can be ...

  12. Energy saving in tunnel entrance lighting.

    NARCIS (Netherlands)

    Schreuder, D.A. & Swart, L.

    1993-01-01

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

  13. Time-resolved scanning tunnelling microscopy

    NARCIS (Netherlands)

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

    2010-01-01

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

  14. Critical issues concerning tunnel ventilation in the super conducting super collider ring tunnel

    International Nuclear Information System (INIS)

    Egilsrud, P.E.

    1989-01-01

    In this paper, the author discusses the problem of designing a ventilation system for the SSC Collider Ring Tunnel. The history of ventilation of tunnels is briefly reviewed and the types of systems used for ventilation of rail, transit and highway tunnels are described in detail. Next, the ventilation system prepared for the Collider Ring Tunnel in the RTK conceptual conventional design report is described. The author questions this design from a safety and practical standpoint. He offers several other solutions which provided a more powerful system for emergencies. One supplies fresh outside air uniformly along the tunnel length. All suggested systems increase costs over the RTK proposed system. The possible problem of troublesome condensation forming on equipment in the tunnel and tunnel walls in hot, humid weather is also a major concern. 5 figs

  15. Temporary closure of the tunnel

    CERN Multimedia

    Relations with the Host States Service

    2005-01-01

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

  16. MR imaging of the carpal tunnel syndrome

    International Nuclear Information System (INIS)

    Elias, D.; Lind, J.; Blair, S.; Light, T.; Wisniewski, R.; Moncado, R.

    1987-01-01

    MR is an ideal noninvasive means to image the structures forming the carpal tunnel in both normal and pathologic conditions. The carpal tunnel syndrome is a frequently encountered entity caused by compression of the median nerve as it passes through the carpal tunnel. This may result from a variety of conditions including edema from acute chronic trauma, rheumatoid tenosynovitis, degenerative joint disease or soft-tissue masses. This exhibit demonstrates the optimal MR imaging techniques to display the structures of the carpal tunnel. The normal anatomy is reviewed and variations in normal anatomy that may predispose to disease are included. Examples of the morphologic changes demonstrated in 20 patients diagnosed with carpal tunnel syndrome are displayed. The exhibit also reviews the findings in 20 postoperative cases

  17. Tunneling Anomalous and Spin Hall Effects.

    Science.gov (United States)

    Matos-Abiague, A; Fabian, J

    2015-07-31

    We predict, theoretically, the existence of the anomalous Hall effect when a tunneling current flows through a tunnel junction in which only one of the electrodes is magnetic. The interfacial spin-orbit coupling present in the barrier region induces a spin-dependent momentum filtering in the directions perpendicular to the tunneling current, resulting in a skew tunneling even in the absence of impurities. This produces an anomalous Hall conductance and spin Hall currents in the nonmagnetic electrode when a bias voltage is applied across the tunneling heterojunction. If the barrier is composed of a noncentrosymmetric material, the anomalous Hall conductance and spin Hall currents become anisotropic with respect to both the magnetization and crystallographic directions, allowing us to separate this interfacial phenomenon from the bulk anomalous and spin Hall contributions. The proposed effect should be useful for proving and quantifying the interfacial spin-orbit fields in metallic and metal-semiconductor systems.

  18. High Surface Area Tunnels in Hexagonal WO₃.

    Science.gov (United States)

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

    2015-07-08

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

  19. Fire safety assessment of tunnel structures

    DEFF Research Database (Denmark)

    Gkoumas, Konstantinos; Giuliani, Luisa; Petrini, Francesco

    2011-01-01

    for upgrading fire safety provisions and tunnel management are also important for existing tunnels. In this study, following a brief introduction of issues regarding the above mentioned aspects, the structural performance of a steel rib for a tunnel infrastructure subject to fire is assessed by means...... durability provisions, commitment to environmental aspects, issues of sustainability and safety assurance, for their whole lifecycle. The design for safety of tunnel infrastructures is a multifaceted process, since there are many aspects that need to be accounted for, regarding different aspects (e.......g. structural and non structural, organizational, human behavior). This is even more truth for the fire safety design of such structures. Fire safety in tunnels is challenging because of the particular environment, bearing in mind also that a fire can occur in different phases of the tunnel’s lifecycle. Plans...

  20. Alternative Matching Scores to Control Type I Error of the Mantel-Haenszel Procedure for DIF in Dichotomously Scored Items Conforming to 3PL IRT and Nonparametric 4PBCB Models

    Science.gov (United States)

    Monahan, Patrick O.; Ankenmann, Robert D.

    2010-01-01

    When the matching score is either less than perfectly reliable or not a sufficient statistic for determining latent proficiency in data conforming to item response theory (IRT) models, Type I error (TIE) inflation may occur for the Mantel-Haenszel (MH) procedure or any differential item functioning (DIF) procedure that matches on summed-item…

  1. Numerical simulation of flows around deformed aircraft model in a wind tunnel

    Science.gov (United States)

    Lysenkov, A. V.; Bosnyakov, S. M.; Glazkov, S. A.; Gorbushin, A. R.; Kuzmina, S. I.; Kursakov, I. A.; Matyash, S. V.; Ishmuratov, F. Z.

    2016-10-01

    To obtain accurate data of calculation method error requires detailed simulation of the experiment in wind tunnel with keeping all features of the model, installation and gas flow. Two examples of such detailed data comparison are described in this paper. The experimental characteristics of NASA CRM model obtained in the ETW wind tunnel (Cologne, Germany), and CFD characteristics of this model obtained with the use of EWT-TsAGI application package are compared. Following comparison is carried out for an airplane model in the T-128 wind tunnel (TsAGI, Russia). It is seen that deformation influence on integral characteristics grows with increasing Re number and, accordingly, the dynamic pressure. CFD methods application for problems of experimental research in the wind tunnel allows to separate viscosity and elasticity effects.

  2. Electrical detection of magnetic skyrmions by tunnelling non-collinear magnetoresistance

    Science.gov (United States)

    Hanneken, Christian; Otte, Fabian; Kubetzka, André; Dupé, Bertrand; Romming, Niklas; von Bergmann, Kirsten; Wiesendanger, Roland; Heinze, Stefan

    2015-12-01

    Magnetic skyrmions are localized non-collinear spin textures with a high potential for future spintronic applications. Skyrmion phases have been discovered in a number of materials and a focus of current research is to prepare, detect and manipulate individual skyrmions for implementation in devices. The local experimental characterization of skyrmions has been performed by, for example, Lorentz microscopy or atomic-scale tunnel magnetoresistance measurements using spin-polarized scanning tunnelling microscopy. Here we report a drastic change of the differential tunnel conductance for magnetic skyrmions that arises from their non-collinearity: mixing between the spin channels locally alters the electronic structure, which makes a skyrmion electronically distinct from its ferromagnetic environment. We propose this tunnelling non-collinear magnetoresistance as a reliable all-electrical detection scheme for skyrmions with an easy implementation into device architectures.

  3. Resonant Magnetization Tunneling in Molecular Magnets: Where is the Inhomogeneous Broadening?

    Science.gov (United States)

    Friedman, Jonathan R.; Sarachik, M. P.

    1998-03-01

    Since the discovery(J. R. Friedman, et al., Phys. Rev. Lett. 76), 3830 (1996) of resonant magnetization tunneling in the molecular magnet Mn_12 there has been intense research into the underlying mechanism of tunneling. Most current theories( V. Dobrovitski and A. Zvezdin, Europhys. Lett. 38), 377 (1997); L. Gunther, Europhys. Lett. 39, 1 (1997); D Garanin and E. Chudnovsky, Phys. Rev. B 56, 11102 (1997). suggest that a local internal (hyperfine or dipole) field transverse to the easy magnetization axis induces tunneling. These theories predict a resonance width orders of magnitude smaller than that actually observed. This discrepancy is attributed to inhomogeneous broadening of the resonance by the random internal fields. We present a detailed study of the tunnel resonance lineshape and show that it is Lorentzian, suggesting it has a deeper physical origin. Since the hyperfine fields are believed to be comparable to the observed width, it is surprising that there is no Gaussian broadening.

  4. Cryogenic wind tunnel technology. A way to measurement at higher Reynolds numbers

    Science.gov (United States)

    Beck, J. W.

    1984-01-01

    The goals, design, problems, and value of cryogenic transonic wind tunnels being developed in Europe are discussed. The disadvantages inherent in low-Reynolds-number (Re) wind tunnel simulations of aircraft flight at high Re are reviewed, and the cryogenic tunnel is shown to be the most practical method to achieve high Re. The design proposed for the European Transonic Wind tunnel (ETW) is presented: parameters include cross section. DISPLAY 83A46484/2 = 4 sq m, operating pressure = 5 bar, temperature = 110-120 K, maximum Re = 40 x 10 to the 6th, liquid N2 consumption = 40,000 metric tons/year, and power = 39,5 MW. The smaller Cologne subsonic tunnel being adapted to cryogenic use for preliminary studies is described. Problems of configuration, materials, and liquid N2 evaporation and handling and the research underway to solve them are outlined. The benefits to be gained by the construction of these costly installations are seen more in applied aerodynamics than in basic research in fluid physics. The need for parallel development of both high Re tunnels and computers capable of performing high-Re numerical analysis is stressed.

  5. Substantiation of parameters of the geometric model of the research reactor core for the calculation using the Monte Carlo method

    Science.gov (United States)

    Radaev, A. I.; Schurovskaya, M. V.

    2015-12-01

    The choice of the spatial nodalization for the calculation of the power density and burnup distribution in a research reactor core with fuel assemblies of the IRT-3M and VVR-KN type using the program based on the Monte Carlo code is described. The influence of the spatial nodalization on the results of calculating basic neutronic characteristics and calculation time is investigated.

  6. Tough but True: School Board Neglect of Bus Safety Led to Government's Overblown, Under-Researched Regulations.

    Science.gov (United States)

    American School Board Journal, 1978

    1978-01-01

    The apparent lack of concern school boards evidenced in the past over school bus safety has precipitated the National Highway Traffic Safety Administration regulations that have angered board members and bus manufacturers alike. It is argued that the new regulations are not based on research. (Author/IRT)

  7. Results of investigations of an 0.010-scale 140A/B configuration (model 72-OTS) of the Rockwell International space shuttle orbiter in the NASA/Langley Research Center unitary plan wind tunnel

    Science.gov (United States)

    Petrozzi, M. T.; Milam, M. D.

    1975-01-01

    Experimental aerodynamic investigations were conducted in the NASA/Langley unitary plan wind tunnel on a sting mounted 0.010-scale outer mold line model of the 140A/B configuration of the Rockwell International Space Shuttle Vehicle. The primary test objectives were to obtain: (1) six component force and moment data for the mated vehicle at subsonic and transonic conditions, (2) effects of configuration build-up, (3) effects of protuberances, ET/orbiter fairings and attach structures, and (4) elevon deflection effects on wing bending moment. Six component aerodynamic force and moment data and base and balance cavity pressures were recorded over Mach numbers of 1.6, 2.0, 2.5, 2.86, 3.9, and 4.63 at a nominal Reynolds number of 20 to the 6th power per foot. Selected configurations were tested at angles of attack and sideslip from -10 deg to +10 deg. For all configurations involving the orbiter, wing bending, and torsion coefficients were measured on the right wing.

  8. Re-evaluating a vision-related quality of life questionnaire with item response theory (IRT) and differential item functioning (DIF) analyses.

    Science.gov (United States)

    van Nispen, Ruth M A; Knol, Dirk L; Langelaan, Maaike; van Rens, Ger H M B

    2011-09-02

    For the Low Vision Quality Of Life questionnaire (LVQOL) it is unknown whether the psychometric properties are satisfactory when an item response theory (IRT) perspective is considered. This study evaluates some essential psychometric properties of the LVQOL questionnaire in an IRT model, and investigates differential item functioning (DIF). Cross-sectional data were used from an observational study among visually-impaired patients (n = 296). Calibration was performed for every dimension of the LVQOL in the graded response model. Item goodness-of-fit was assessed with the S-X(2)-test. DIF was assessed on relevant background variables (i.e. age, gender, visual acuity, eye condition, rehabilitation type and administration type) with likelihood-ratio tests for DIF. The magnitude of DIF was interpreted by assessing the largest difference in expected scores between subgroups. Measurement precision was assessed by presenting test information curves; reliability with the index of subject separation. All items of the LVQOL dimensions fitted the model. There was significant DIF on several items. For two items the maximum difference between expected scores exceeded one point, and DIF was found on multiple relevant background variables. Item 1 'Vision in general' from the "Adjustment" dimension and item 24 'Using tools' from the "Reading and fine work" dimension were removed. Test information was highest for the "Reading and fine work" dimension. Indices for subject separation ranged from 0.83 to 0.94. The items of the LVQOL showed satisfactory item fit to the graded response model; however, two items were removed because of DIF. The adapted LVQOL with 21 items is DIF-free and therefore seems highly appropriate for use in heterogeneous populations of visually impaired patients.

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

    Science.gov (United States)

    Le Péchon, Jean-Claude

    2006-01-01

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

  10. Magnetoresistance of galfenol-based magnetic tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Gobaut, B., E-mail: benoit.gobaut@elettra.eu [Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, Area Science Park, 34149 Trieste (Italy); Vinai, G.; Castán-Guerrero, C.; Krizmancic, D.; Panaccione, G.; Torelli, P. [Laboratorio TASC, IOM-CNR, S.S. 14km 163.5, Basovizza, 34149 Trieste (Italy); Rafaqat, H. [Laboratorio TASC, IOM-CNR, S.S. 14km 163.5, Basovizza, 34149 Trieste (Italy); ICTP, Trieste (Italy); Roddaro, S. [Laboratorio TASC, IOM-CNR, S.S. 14km 163.5, Basovizza, 34149 Trieste (Italy); NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza S. Silvestro 12, 56127 Pisa (Italy); Rossi, G. [Laboratorio TASC, IOM-CNR, S.S. 14km 163.5, Basovizza, 34149 Trieste (Italy); Dipartimento di Fisica, Università di Milano, via Celoria 16, 20133 Milano (Italy); Eddrief, M.; Marangolo, M. [Sorbonne Universités, UPMC Paris 06, CNRS-UMR 7588, Institut des Nanosciences de Paris, 75005, Paris (France)

    2015-12-15

    The manipulation of ferromagnetic layer magnetization via electrical pulse is driving an intense research due to the important applications that this result will have on memory devices and sensors. In this study we realized a magnetotunnel junction in which one layer is made of Galfenol (Fe{sub 1-x}Ga{sub x}) which possesses one of the highest magnetostrictive coefficient known. The multilayer stack has been grown by molecular beam epitaxy and e-beam evaporation. Optical lithography and physical etching have been combined to obtain 20x20 micron sized pillars. The obtained structures show tunneling conductivity across the junction and a tunnel magnetoresistance (TMR) effect of up to 11.5% in amplitude.

  11. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

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

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc biased...... at different points in the current-voltage characteristic. Both numerical calculations based on the Tien-Gordon theory and 70-GHz microwave experiments have confirmed the wide dynamic range (more than 15-dB attenuation for one stage) and the low insertion loss in the ''open'' state. The performance of a fully...... integrated submillimeter receiver circuit which comprises a flux-flow oscillator (FFO) as local oscillator, a superconducting variable attenuator, and a microwave SIS detector with tuned-out capacitance is also reported....

  12. Homoepitaxial graphene tunnel barriers for spin transport

    Directory of Open Access Journals (Sweden)

    Adam L. Friedman

    2016-05-01

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

  13. Trajectories and traversal times in quantum tunneling

    International Nuclear Information System (INIS)

    Huang, Zhi Hong.

    1989-01-01

    The classical concepts of trajectories and traversal times applied to quantum tunneling are discussed. By using the Wentzel-Kramers-Brillouin approximation, it is found that in a forbidden region of a multidimensional space the wave function can be described by two sets of trajectories, or equivalently by two sets of wave fronts. The trajectories belonging to different sets are mutually orthogonal. An extended Huygens construction is proposed to determine these wave fronts and trajectories. In contrast to the classical results in the allowed region, these trajectories couple to each other. However, if the incident wave is normal to the turning surface, the trajectories are found to be independent and can be determined by Newton's equations of motion with inverted potential and energy. The multidimensional tunneling theory is then applied to the scanning tunneling microscope to calculate the current density distribution and to derive the expressions for the lateral resolution and the surface corrugation amplitude. The traversal time in quantum tunneling, i.e. tunneling time, is found to depend on model calculations and simulations. Computer simulation of a wave packet tunneling through a square barrier is performed. Several approaches, including the phase method, Larmor clock, and time-dependent barrier model, are investigated. For a square barrier, two characteristic times are found: One is equal to the barrier width divided by the magnitude of the imaginary velocity; the other is equal to the decay length divided by the incident velocity. It is believed that the tunneling time can only be defined operationally

  14. Topographic anatomy of the ulnar tunnel.

    Science.gov (United States)

    Gil, Young-Chun; Shin, Kang-Jae; Lee, Ju-Young; Hu, Kyung-Seok; Kim, Hee-Jin; Song, Wu-Chul; Koh, Ki-Seok

    2015-09-01

    The aim of this study was to clarify the definition of the anterior wall of the ulnar tunnel and to reveal the topographical characteristics of the various components of the ulnar tunnel. Twenty-two forearms from 11 embalmed cadavers (7 males, 4 females; mean age, 67.8 years) were carefully dissected. In all cases, the anterior wall of the ulnar tunnel comprised the hypothenar fascia, which originated from the tendon of the flexor carpi ulnaris muscle. The palmar carpal ligament, the distal extent of the antebrachial fascia, was located deep to the anterior wall and formed only the anterior boundary of the proximal hiatus of the ulnar tunnel. The hypothenar fascia was attached to the flexor retinaculum at 15.2 mm lateral to the pisiform bone. However, the palmar carpal ligament was attached to the flexor retinaculum just lateral to the ulnar artery; the distance between the attachment of the palmar carpal ligament and the pisiform bone was 8.7 mm. Anatomical variations potentially associated with ulnar nerve compression were observed. The accessory abductor digiti minimi muscle and the fibrous band crossing the ulnar nerve in the ulnar tunnel were found in 27 and 23 % of forearms, respectively. A more detailed description of the anterior wall of the ulnar tunnel than was previously available is presented herein, and topographic and metric data regarding each structure of the tunnel are reported.

  15. Wind Tunnel Testing of a 6%-Scale Large Civil Tilt Rotor Model in Airplane and Helicopter Modes

    Science.gov (United States)

    2014-01-01

    In April 2012 and October 2013, NASA and the U.S. Army jointly conducted a wind tunnel test program examining two notional large tilt rotor designs... rotors in the U.S. Army 7- by 10-foot wind tunnel at NASA Ames Research Center. Measurements of all six forces and moments acting on the airframe...airframe models were tested without rotors in the U.S. Army 7- by 10-foot wind tunnel at NASA Ames Research Center. This test entry represents the first

  16. Tunneling mechanism in higher-dimensional rotating black hole with a cosmological constant in the approach of dimensional reduction

    Science.gov (United States)

    Li-Chun, Zhang; Huai-Fan, Li; Ren, Zhao

    2011-06-01

    Recently, Umetsu applied the tunneling method to the research on Hawking radiation of black holes using the dimensional reduction method near the horizon. In a simple way he obtained the radiation temperature of Kerr-Newman black hole. In this paper, using the dimensional reduction method near the horizon, we apply the tunneling method to the research on Hawking radiation of a general Kerr-de Sitter metrics in all dimensions. Our results support the views of Umetsu and extend the tunneling method proposed by Parikh and Wilczek.

  17. Investigation of silicide-induced-dopant-activation for steep tunnel junction in tunnel field effect transistor (TFET)

    Science.gov (United States)

    Kim, Sihyun; Kwon, Dae Woong; Park, Euyhwan; Lee, Junil; Lee, Roongbin; Lee, Jong-Ho; Park, Byung-Gook

    2018-02-01

    Numerous researches for making steep tunnel junction within tunnel field-effect transistor (TFET) have been conducted. One of the ways to make an abrupt junction is source/drain silicidation, which uses the phenomenon often called silicide-induced-dopant-segregation. It is revealed that the silicide process not only helps dopants to pile up adjacent to the metal-silicon alloy, also induces the dopant activation, thereby making it possible to avoid additional high temperature process. In this report, the availability of dopant activation induced by metal silicide process was thoroughly investigated by diode measurement and device simulation. Metal-silicon (MS) diodes having p+ and n+ silicon formed on the p- substrate exhibit the characteristics of ohmic and pn diodes respectively, for both the samples with and without high temperature annealing. The device simulation for TFETs with dopant-segregated source was also conducted, which verified enhanced DC performance.

  18. A Model for the Behavior of Magnetic Tunnel Junctions

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Bryan John [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    A magnetic tunnel junction is a device that changes its electrical resistance with a change in an applied magnetic field. A typical junction consists of two magnetic electrodes separated by a nonmagnetic insulating layer. The magnetizations of the two electrodes can have two possible extreme configurations, parallel and antiparallel. The antiparallel configuration is observed to have the higher measured resistance and the parallel configuration has the lower resistance. To switch between these two configurations a magnetic field is applied to the device which is primarily used to change the orientation of the magnetization of one electrode usually called the free layer, although with sufficient high magnetic field the orientation of the magnetizations of both of the electrodes can be changed. The most commonly used models for describing and explaining the electronic behavior of tunnel junctions are the Simmons model and the Brinkman model. However, both of these models were designed for simple, spin independent tunneling. The Simmons model does not address the issue of applied magnetic fields nor does it address the form of the electronic band structure in the metallic electrodes, including the important factor of spin polarization. The Brinkman model is similar, the main difference between the two models being the shape of the tunneling barrier potential between the two electrodes. Therefore, the research conducted in this thesis has developed a new theoretical model that addresses these important issues starting from basic principles. The main features of the new model include: the development of equations for true spin dependent tunneling through the insulating barrier, the differences in the orientations of the electrode magnetizations on either side of the barrier, and the effects of the density of states function on the behavior of the junction. The present work has explored densities of states that are more realistic than the simplified free electron density

  19. Radiation environment in the tunnel of a high-energy proton accelerator at energies near 1 TeV

    International Nuclear Information System (INIS)

    McCaslin, J.B.; Sun, R.K.S.; Swanson, W.P.

    1987-12-01

    Neutron energy spectra, fluence distributions and rates in the FNAL Tevatron tunnel are summarized. This work has application to radiation damage to electronics and research equipment at high energy accelerators, as well as to radiological protection. 7 refs., 4 figs

  20. Tunneling spin injection into single layer graphene.

    Science.gov (United States)

    Han, Wei; Pi, K; McCreary, K M; Li, Yan; Wong, Jared J I; Swartz, A G; Kawakami, R K

    2010-10-15

    We achieve tunneling spin injection from Co into single layer graphene (SLG) using TiO₂ seeded MgO barriers. A nonlocal magnetoresistance (ΔR(NL)) of 130  Ω is observed at room temperature, which is the largest value observed in any material. Investigating ΔR(NL) vs SLG conductivity from the transparent to the tunneling contact regimes demonstrates the contrasting behaviors predicted by the drift-diffusion theory of spin transport. Furthermore, tunnel barriers reduce the contact-induced spin relaxation and are therefore important for future investigations of spin relaxation in graphene.

  1. Thermal stability of tunneling spin polarization

    International Nuclear Information System (INIS)

    Kant, C.H.; Kohlhepp, J.T.; Paluskar, P.V.; Swagten, H.J.M.; Jonge, W.J.M. de

    2005-01-01

    We present a study of the thermal stability of tunneling spin polarization in Al/AlOx/ferromagnet junctions based on the spin-polarized tunneling technique, in which the Zeeman-split superconducting density of states in the Al electrode is used as a detector for the spin polarization. Thermal robustness of the polarization, which is of key importance for the performance of magnetic tunnel junction devices, is demonstrated for post-deposition anneal temperatures up to 500 o C with Co and Co 90 Fe 10 top electrodes, independent of the presence of an FeMn layer on top of the ferromagnet

  2. The Thames Tideway Tunnel (3/3)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

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

  3. Tunneling decay of self-gravitating vortices

    Science.gov (United States)

    Dupuis, Éric; Gobeil, Yan; Lee, Bum-Hoon; Lee, Wonwoo; MacKenzie, Richard; Paranjape, Manu B.; Yajnik, Urjit A.; Yeom, Dong-han

    2018-01-01

    We investigate tunneling decay of false vortices in the presence of gravity, in which vortices are trapped in the false vacuum of a theory of scalar electrodynamics in three dimensions. The core of the vortex contains magnetic flux in the true vacuum, while outside the vortex is the appropriate topologically nontrivial false vacuum. We numerically obtain vortex solutions which are classically stable; however, they could decay via tunneling. To show this phenomenon, we construct the proper junction conditions in curved spacetime. We find that the tunneling exponent for the vortices is half that for Coleman-de Luccia bubbles and discuss possible future applications.

  4. Mechanical tunnel excavation in welded tuff

    International Nuclear Information System (INIS)

    Sperry, P.E.

    1991-01-01

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

  5. Tunneling time distribution by means of Nelson's quantum ...

    Indian Academy of Sciences (India)

    We construct a tunneling time distribution by means of Nelson's quantum mechanics and investigate statistical properties of the tunneling time distribution. As a result, we find that the relationship between the average and the variance of the tunneling time shows 'wave-particle duality'. Keywords. Tunneling time distribution ...

  6. Apparatus and method for large tunnel excavation in hard rock

    International Nuclear Information System (INIS)

    Altseimer, J.H.; Hanold, R.J.

    1975-01-01

    A tunneling machine is described for producing large tunnels in rock by progressive detachment of the tunnel core by thermal melting a boundary kerf into the tunnel face and simultaneously forming an initial tunnel wall support by deflecting the molten materials against the tunnel walls to provide, when solidified, a continuous liner; and fragmenting the tunnel core circumscribed by the kerf by thermal stress fracturing and in which the heat required for such operations is supplied by a compact nuclear reactor. (U.S.)

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

    International Nuclear Information System (INIS)

    Teeny, Nicolas

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Teeny, Nicolas

    2016-10-18

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

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

    Directory of Open Access Journals (Sweden)

    QIU Daohong

    2014-08-01

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

  10. Collapsed Shape of Shallow Unlined Tunnels Based on Functional Catastrophe Theory

    Directory of Open Access Journals (Sweden)

    Chengping Zhang

    2015-01-01

    Full Text Available This paper investigates the collapse mechanisms and possible collapsing block shapes of shallow unlined tunnels under conditions of plane strain. The analysis is performed following the framework from a branch of catastrophe theory, functional catastrophe theory. First, the basic principles of functional catastrophe theory are introduced. Then, an analytical solution for the shape curve of the collapsing block of a shallow unlined tunnel is derived using functional catastrophe theory based on the nonlinear Hoek-Brown failure criterion. The effects of the rock mass parameters of the proposed method on the shape and weight of the collapsing block are examined. Moreover, a critical cover depth expression to classify deep and shallow tunnels is proposed. The analytical results are consistent with those obtained by numerical simulation using the particle flow code, demonstrating the validity of the proposed analytical method. The obtained formulas can be used to predict the height and width of the collapsing block of a shallow unlined tunnel and to provide a direct estimate of the overburden on the tunnel lining. The obtained formulas can be easily used by tunnel engineers and researchers due to their simplicity.

  11. Magneto-Seebeck effect and thermal torques in magnetic tunnel junctions

    Science.gov (United States)

    Muenzenberg, Markus

    2012-02-01

    Creating temperature gradients in magnetic nanostructures has resulted in a new research direction, i.e., the combination of magneto- and thermoelectric effects. Magnetic tunnel devices, known for application as magnetic sensor in hard disc drives or magnetic random access memories (MRAM) show large magnetoresistance. We show that in nanoscale magnetic tunnel junctions, the Seebeck voltage in a heat gradient can be controlled via the magnetization. The Seebeck coefficient changes during the transition from a parallel to an antiparallel magnetic configuration in a tunnel junction -- the magneto-Seebeck effect. In that respect, it is the analog to the tunneling magnetoresistance and thus is called tunneling magneto-Seebeck effect (or tunneling magnetothermopower). The change in Seebeck coefficients is in the order of the voltages known from the charge-Seebeck effect in semiconductors (up to 100 μV/K). Their size and sign can be delicately controlled by the composition of the electrodes' atomic layers adjacent to the barrier and the temperature and we observe a characteristic sign change from positive to negative magneto-Seebeck effects as theoretically predicted. It is known that generally strong electronic asymmetry at around the Fermi level results in a large Seebeck effect. Here the magnetization dependence of the charge-Seebeck coefficients varying up to >100% for the parallel and the antiparallel originates from the half-metallic like transmission of the tunnel junction. Using heating with ultrafast laser pulses, these thermal gradients can be of up to 20 K across the tunnel barrier. We demonstrate that we can achieve the parameters predicted, where by thermal torques magnetization switching is expected. This allows to conceptually think of MRAM's driven by heat gradients only. [4pt] [1] M. Walter, et al. Nature Mater. 10, 742 (2011).

  12. Computed tomography value and tunnel enlargement of round and rounded rectangular femoral bone tunnel for anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Takata, Yasushi; Nakase, Junsuke; Numata, Hitoaki; Oshima, Takeshi; Tsuchiya, Hiroyuki

    2016-11-01

    We developed a novel technique for anatomical single-bundle anterior cruciate ligament (ACL) reconstruction: creation of a rounded rectangular femoral bone tunnel. The purpose of this study was to compare the computed tomography (CT) value and tunnel enlargement ratio of the femoral bone tunnel with those of round tunnel ACL reconstruction. We included 39 knees that underwent round tunnel ACL reconstruction and 42 that underwent rounded rectangular ACL reconstruction. To evaluate the CT value, we compared the CT images approximately 1 week after surgery. Making a parallel slice toward the opening of bone tunnels to a depth of 3 mm, we evaluated the CT value of eight directions in the bone tunnel wall. To evaluate tunnel enlargement, we compared CT images approximately 1 week after surgery with images taken 3 months after surgery. Using a parallel slice toward the opening of the bone tunnel, we measured the bone tunnel area and calculated the tunnel enlargement ratio. The level of significance was P value was significantly increased for the rounded rectangular tunnel in comparison with the round tunnel in almost all directions (P < 0.05). The rounded rectangular tunnel area enlargement ratio was significantly lower (round, 110 ± 38 %; rounded rectangular, 73 ± 37 %; P = 0.001). The rounded rectangular tunnel could have a compression effect on the cancellous bone and reduce enlargement of the bone tunnel.

  13. Quantum size effects on spin-tunneling time in a magnetic resonant tunneling diode

    OpenAIRE

    Saffarzadeh, Alireza; Daqiq, Reza

    2009-01-01

    We study theoretically the quantum size effects of a magnetic resonant tunneling diode (RTD) with a (Zn,Mn)Se dilute magnetic semiconductor layer on the spin-tunneling time and the spin polarization of the electrons. The results show that the spin-tunneling times may oscillate and a great difference between the tunneling time of the electrons with opposite spin directions can be obtained depending on the system parameters. We also study the effect of structural asymmetry which is related to t...

  14. Correlations of Platooning Track Test and Wind Tunnel Data

    Energy Technology Data Exchange (ETDEWEB)

    Lammert, Michael P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kelly, Kenneth J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yanowitz, Janet [Ecoengineering

    2018-02-02

    In this report, the National Renewable Energy Laboratory analyzed results from multiple, independent truck platooning projects to compare and contrast track test results with wind tunnel test results conducted by Lawrence Livermore National Laboratory (LLNL). Some highlights from the report include compiled data, and results from four independent SAE J1321 full-size track test campaigns that were compared to LLNL wind tunnel testing results. All platooning scenarios tested demonstrated significant fuel savings with good correlation relative to following distances, but there are still unanswered questions and clear opportunities for system optimization. NOx emissions showed improvements from NREL tests in 2014 to Auburn tests in 2015 with respect to J1321 platooning track testing of Peloton system. NREL evaluated data from Volpe's Naturalistic Study of Truck Following Behavior, which showed minimal impact of naturalistic background platooning. We found significant correlation between multiple track studies, wind tunnel tests, and computational fluid dynamics, but also showed that there is more to learn regarding close formation and longer-distance effects. We also identified potential areas for further research and development, including development of advanced aerodynamic designs optimized for platooning, measurement of platoon system performance in traffic conditions, impact of vehicle lateral offsets on platooning performance, and characterization of the national potential for platooning based on fleet operational characteristics.

  15. STRESS STATE OF TRANSVERSELY ISOTROPIC ROCKS NEAR PRESSURIZED HYDRAULIC TUNNEL OF HORSESHOE CROSS-SECTION

    Directory of Open Access Journals (Sweden)

    Bautdinov Damir Tahirovich

    2017-10-01

    Full Text Available The parametric analysis of the stress state of a transversally isotropic rock mass near a pressurized hydraulic tunnel of a box-shaped form is carried out. Pressurized hydro-technical tunnels of box-shaped cross-section are widely used in the field of hydraulic engineering construction and are one of the complex, labor-intensive and expensive types of structures that make up the main structures of waterworks, melioration systems and water supply systems. As a culvert and water supply facilities they are built underground if the open excavation is impossible or not economical, or when the tunnel runs through a densely populated or densely built-up area, or when landslides, screes, rockfalls are possible. Violation of integrity of the rock mass, in particular, caused by tunneling, modifies the stress-strain state (SSS of the rock mass, which leads to appearance of tensile stresses in some places, and in some cases, to significant compressive stresses. If these stresses exceed the design strengths of rock to tension and compression, respectively, then the collapse of the working roof and buckling of the side walls and the bottom of the tunnel may occur. Subject: analysis of the stress state of transversally isotropic rocks near the pressurized hydraulic tunnel of horseshoe cross-section caused by the internal head of water. Research objectives: determination of real values of circumferential stresses along the development contour. Materials and methods: solution of the problem of plane deformation of the theory of elasticity for a transversely isotropic medium containing tunnel excavation cannot be obtained by analytical methods, and therefore the stress-strain analysis was carried out by the finite element method using the ANSYS software package, MCE. Results: determination of stresses along the development contour, construction of diagrams and graphs showing the effects of the anisotropy conditions and Poisson’s ratio. The tangential stresses

  16. Tunnel magnetoresistance in double spin filter junctions

    International Nuclear Information System (INIS)

    Saffarzadeh, Alireza

    2003-01-01

    We consider a new type of magnetic tunnel junction, which consists of two ferromagnetic tunnel barriers acting as spin filters (SFs), separated by a nonmagnetic metal (NM) layer. Using the transfer matrix method and the free-electron approximation, the dependence of the tunnel magnetoresistance (TMR) on the thickness of the central NM layer, bias voltage and temperature in the double SF junction are studied theoretically. It is shown that the TMR and electron-spin polarization in this structure can reach very large values under suitable conditions. The highest value of the TMR can reach 99%. By an appropriate choice of the thickness of the central NM layer, the degree of spin polarization in this structure will be higher than that of the single SF junctions. These results may be useful in designing future spin-polarized tunnelling devices

  17. Tunneling time in space fractional quantum mechanics

    Science.gov (United States)

    Hasan, Mohammad; Mandal, Bhabani Prasad

    2018-02-01

    We calculate the time taken by a wave packet to travel through a classically forbidden region of space in space fractional quantum mechanics. We obtain the close form expression of tunneling time from a rectangular barrier by stationary phase method. We show that tunneling time depends upon the width b of the barrier for b → ∞ and therefore Hartman effect doesn't exist in space fractional quantum mechanics. Interestingly we found that the tunneling time monotonically reduces with increasing b. The tunneling time is smaller in space fractional quantum mechanics as compared to the case of standard quantum mechanics. We recover the Hartman effect of standard quantum mechanics as a special case of space fractional quantum mechanics.

  18. LEP sees the end of the tunnel

    CERN Multimedia

    2002-01-01

    After 14 months, which have seen the removal of 30,000 tonnes of material from the tunnel, the LEP dismantling operation has now been completed. LHC installation, which will be subject to new safety rules, can go ahead.

  19. Roughcastle tunnel above an old mine

    Energy Technology Data Exchange (ETDEWEB)

    Sakalas, C.F.; Beadman, D.R.; Manning, S.R. [High-Point Rendel (United Kingdom)

    2002-06-01

    Construction of the 147 m long Roughcastle Tunnel, part of the Millennium Link connecting the Forth and Clyde canal and the Union canal at Falkirk, Scotland, provided an unusual challenge for designer and contractor alike. It overlays an unfilled, abandoned stoop-and pillar fireclay mine at shallow depth. Boreholes were drilled into the mine to ascertain the rock quality in the roof and pillars, and ultrasonic surveys carried to determine the condition of the workings to assess the risk, and the possible effect on the tunnel of a mine collapse during the tunnel's 120 year design life. The tunnel was successfully completed using a single pass sprayed concrete lining technique in a mixed face of stiff glacial till overlying Lower Coal Measures comprising interbedded sandstones, mudstones and coals. 4 photos.

  20. Engineering a de Novo Transport Tunnel

    Czech Academy of Sciences Publication Activity Database

    Březovský, J.; Babková, P.; Degtjarik, O.; Fořtová, A.; Gora, A.; Iermak, I.; Řezáčová, Pavlína; Dvořák, P.; Kutá Smatanová, I.; Prokop, Z.; Chaloupková, R.; Damborský, J.

    2016-01-01

    Roč. 6, č. 11 (2016), s. 7597-7610 ISSN 2155-5435 Institutional support: RVO:61388963 Keywords : transport tunnel * protein engineering * protein design * activity * specificity Subject RIV: CE - Biochemistry Impact factor: 10.614, year: 2016

  1. Dynamical quenching of tunneling in molecular magnets

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  2. Dielectric Sensors Based on Electromagnetic Energy Tunneling

    Directory of Open Access Journals (Sweden)

    Omar Siddiqui

    2015-03-01

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

  3. Teelt van vruchtgewassen in lage tunnels

    NARCIS (Netherlands)

    Wijk, van C.A.P.; Geven, C.G.M.

    1994-01-01

    Een aantal warmteminnende vruchtgewassen zijn beproefd in lage tunnels en vergeleken met onbedekte teelt en met kasteelt. Het betrof aubergine, paprika, peper en diverse typen meloen. Daar is courgette als vergelijkend gewas aan toegevoegd

  4. Engineering a de Novo Transport Tunnel

    Czech Academy of Sciences Publication Activity Database

    Březovský, J.; Babková, P.; Degtjarik, Oksana; Fořtová, A.; Gora, A.; Iermak, Iuliia; Řezáčová, Pavlína; Dvořák, P.; Kutá Smatanová, Ivana; Prokop, Z.; Chaloupková, R.; Damborský, J.

    2016-01-01

    Roč. 6, č. 11 (2016), s. 7597-7610 ISSN 2155-5435 Institutional support: RVO:61388971 ; RVO:68378050 Keywords : transport tunnel * protein engineering * protein design Subject RIV: EE - Microbiology, Virology Impact factor: 10.614, year: 2016

  5. A critical examination of expansion tunnel performance

    Science.gov (United States)

    Miller, C. G.

    1978-01-01

    An experimental study of the performance of the expansion tunnel for various test gases and range of quiescent acceleration section and nozzle pressure, nozzle geometric area ratio, and nozzle axial station has been performed. Flow diagnostics used to examine expansion tunnel flow characteristics were time histories and profiles of pitot pressure and axial component of flow velocity. The purpose of this study was to determine experimentally what limitations might restrict predicted operational flexibility and the advantages and disadvantages of this mode of operation as compared to the expansion tube. Results are presented which demonstrate the expansion tunnel offers several advantages over the expansion tube, but the severity of the disadvantages of the tunnel makes the expansion tube mode of operation the more desirable for performing hypersonic-hypervelocity aerothermodynamic studies of proposed entry configurations.

  6. TBM tunneling on the Yucca Mountain Project

    International Nuclear Information System (INIS)

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

    1995-01-01

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

  7. Computer graphic of LHC in the tunnel

    CERN Multimedia

    1996-01-01

    A computer-generated image of the LHC particle accelerator at CERN in the tunnel originally built for the LEP accelerator that was closed in 2000. The cross-section of an LHC superconducting dipole magnet is also seen.

  8. Low Speed Wind Tunnel Facility (LSWTF)

    Data.gov (United States)

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

  9. Air quality assessment in Salim Slam Tunnel

    International Nuclear Information System (INIS)

    El-Fadel, M.; Hashisho, Z.; Saikaly, P.

    1999-01-01

    Full text.Vehicle emissions constitute a serious occupational environmental hazard particularly in confined spaces such as tunnels and underground parking garages. these emissions at elevated concentrations, can cause adverse health effects, which range from nausea and eye irritation to mutagenicity, carcinogenicity and even death. This paper presents an environmental air quality assessment in a tunnel located in a highly congested urban area. For this purpose, air samples were collected and analyzed for the presence of primary air pollutants, priority metals, and volatile organic carbons. Air quality modeling was conducted to simulate variations of pollutant concentrations in the tunnel under worst case scenarios including traffic congestion and no air ventilation. Field measurements and mathematical simulation results were used to develop a strategy for proper air quality management in tunnels

  10. Proton tunnelling in intermolecular hydrogen bonds

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-04-01

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

  11. Calculations of air cooler for new subsonic wind tunnel

    Science.gov (United States)

    Rtishcheva, A. S.

    2017-10-01

    As part of the component development of TsAGI’s new subsonic wind tunnel where the air flow velocity in the closed test section is up to 160 m/sec hydraulic and thermal characteristics of air cooler are calculated. The air cooler is one of the most important components due to its highest hydraulic resistance in the whole wind tunnel design. It is important to minimize its hydraulic resistance to ensure the energy efficiency of wind tunnel fans and the cost-cutting of tests. On the other hand the air cooler is to assure the efficient cooling of air flow in such a manner as to maintain the temperature below 40 °C for seamless operation of measuring equipment. Therefore the relevance of this project is driven by the need to develop the air cooler that would demonstrate low hydraulic resistance of air and high thermal effectiveness of heat exchanging surfaces; insofar as the cooling section must be given up per unit time with the amount of heat Q=30 MW according to preliminary evaluations. On basis of calculation research some variants of air cooler designs are proposed including elliptical tubes, round tubes, and lateral plate-like fins. These designs differ by the number of tubes and plates, geometrical characteristics and the material of finned surfaces (aluminium or cooper). Due to the choice of component configurations a high thermal effectiveness is achieved for finned surfaces. The obtained results form the basis of R&D support in designing the new subsonic wind tunnel.

  12. Resonant tunneling in small current-biased Josephson Junctions

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, John Mark [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    Effects of resonant tunneling between bound quantum states of a current-biased Josephson tunnel junction is studied both theoretically and experimentally. Several effects are predicted to arise from resonant tunneling, including a series of voltage peaks along the supercurrent branch of the current-voltage characteristic, and enhanced rate of escape from zero voltage state to voltage state at particular values of bias current. A model is developed to estimate magnitude and duration of voltage peaks, and to estimate enhancement of the escape rate, which appears as peaks in the rate as a function of bias current. An experimental investigation was carried out in an attempt to observe these predicted peaks in the escape rate distribution in a current-biased DC SQUID, which is shown to be dynamically equivalent to a Josephson junction with adjustable critical current. Electrical contact to each SQUID (fabricated from aluminium) was made through high resistance thin film leads located on the substrate. These resistors provided a high impedance at the plasma frequency which is for the isolation of the SQUID from its electromagnetic environment. Measurements were carried out on a dilution refrigerator at temperatures as low as 19 mK. No evidence was found for resonant tunneling; this is attributed to effective temperatures of hundreds of millikelvin. The behavior is well explained by a heating model where the high effective temperatures are generated by ohmic heating of the electron gas of the isolation resistors, which decouples from the phonon system (hot electron effect). The prospects for further theoretical and experimental research are discussed.

  13. Wind Tunnel Test of the SMART Active Flap Rotor

    Science.gov (United States)

    Straub, Friedrich K.; Anand, Vaidyanthan R.; Birchette, Terrence S.; Lau, Benton H.

    2009-01-01

    Boeing and a team from Air Force, NASA, Army, DARPA, MIT, UCLA, and U. of Maryland have successfully completed a wind-tunnel test of the smart material actuated rotor technology (SMART) rotor in the 40- by 80-foot wind-tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center. The Boeing SMART rotor is a full-scale, five-bladed bearingless MD 900 helicopter rotor modified with a piezoelectric-actuated trailing edge flap on each blade. The eleven-week test program evaluated the forward flight characteristics of the active-flap rotor at speeds up to 155 knots, gathered data to validate state-of-the-art codes for rotor aero-acoustic analysis, and quantified the effects of open and closed loop active flap control on rotor loads, noise, and performance. The test demonstrated on-blade smart material control of flaps on a full-scale rotor for the first time in a wind tunnel. The effectiveness of the active flap control on noise and vibration was conclusively demonstrated. Results showed significant reductions up to 6dB in blade-vortex-interaction and in-plane noise, as well as reductions in vibratory hub loads up to 80%. Trailing-edge flap deflections were controlled within 0.1 degrees of the commanded value. The impact of the active flap on control power, rotor smoothing, and performance was also demonstrated. Finally, the reliability of the flap actuation system was successfully proven in more than 60 hours of wind-tunnel testing.

  14. Scanning tunneling microscopy studies of diamond films and optoelectronic materials

    Science.gov (United States)

    Perez, Jose M.

    1993-01-01

    In this report, we report on progress achieved from 12/1/92 to 10/1/93 under the grant entitled 'Scanning Tunneling Microscopy Studies of Diamond Films and Optoelectronic Materials'. We have set-up a chemical vapor deposition (CVD) diamond film growth system and a Raman spectroscopy system to study the nucleation and growth of diamond films with atomic resolution using scanning tunneling microscopy (STM). A unique feature of the diamond film growth system is that diamond films can be transferred directly to the ultrahigh vacuum (UHV) chamber of a scanning tunneling microscope without contaminating the films by exposure to air. The University of North Texas (UNT) provided $20,000 this year as matching funds for the NASA grant to purchase the diamond growth system. In addition, UNT provided a Coherent Innova 90S Argon ion laser, a Spex 1404 double spectrometer, and a Newport optical table costing $90,000 to set-up the Raman spectroscopy system. The CVD diamond growth system and Raman spectroscopy system will be used to grow and characterize diamond films with atomic resolution using STM as described in our proposal. One full-time graduate student and one full-time undergraduate student are supported under this grant. In addition, several graduate and undergraduate students were supported during the summer to assist in setting-up the diamond growth and Raman spectroscopy systems. We have obtained research results concerning STM of the structural and electronic properties of CVD grown diamond films, and STM and scanning tunneling spectroscopy of carbon nanotubes. In collaboration with the transmission electron microscopy (TEM) group at UNT, we have also obtained results concerning the optoelectronic material siloxene. These results were published in refereed scientific journals, submitted for publication, and presented as invited and contributed talks at scientific conferences.

  15. Detecting DNS Tunnels Using Character Frequency Analysis

    OpenAIRE

    Born, Kenton; Gustafson, David

    2010-01-01

    High-bandwidth covert channels pose significant risks to sensitive and proprietary information inside company networks. Domain Name System (DNS) tunnels provide a means to covertly infiltrate and exfiltrate large amounts of information passed network boundaries. This paper explores the possibility of detecting DNS tunnels by analyzing the unigram, bigram, and trigram character frequencies of domains in DNS queries and responses. It is empirically shown how domains follow Zipf's law in a simil...

  16. An epitaxial ferroelectric tunnel junction on silicon.

    Science.gov (United States)

    Li, Zhipeng; Guo, Xiao; Lu, Hui-Bin; Zhang, Zaoli; Song, Dongsheng; Cheng, Shaobo; Bosman, Michel; Zhu, Jing; Dong, Zhili; Zhu, Weiguang

    2014-11-12

    Epitaxially grown functional perovskites on silicon (001) and the ferroelectricity of a 3.2 nm thick BaTiO3 barrier layer are demonstrated. The polarization-switching-induced change in tunneling resistance is measured to be two orders of magnitude. The obtained results suggest the possibility of integrating ferroelectric tunnel junctions as binary data storage media in non-volatile memory cells on a silicon platform. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. The Femarnbelt Tunnel: Regional Development Perspectives

    DEFF Research Database (Denmark)

    Matthiessen, Christian Wichmann; Lundhus, Peter

    2011-01-01

    structures (bridges/ tunnels) spanning international waterways. They concentrate traffic flows and create strong transport corridors and are the basis of new regional development regimes. In early 2011, following almost two years of extensive work on different conceptual designs for the fixed link...... it was decided that an immersed tunnel should form the basis for the continuous planning of the project, including the environmental impact studies. Completion of the link is scheduled for 2020...

  18. Numerical modeling of tunneling-induced seismicity

    Science.gov (United States)

    Rinaldi, Antonio Pio; Urpi, Luca

    2017-04-01

    Removal of rock mass in mining environment has been associated since long-time with seismic event of magnitude 3 and above, with the potential to cause damage to the infrastructures or even loss of human life. Although with similarities with mining, relatively unknown up to now are seismic events induced by tunneling. However with modern mechanized tunneling techniques, making possible to digging deeper and longer underground infrastructure, the risk is not negligible. As an example, the excavation of the 57km long Gotthard Base Tunnel has been associated more than hundred seismic events, with the largest one having magnitude of ML 2.4, damaging the tunnel infrastructures. For future scenario of deep geological storage of nuclear waste, tunneling will constitute the primary activity during site construction. Hence, it will be crucial to understand the risk associated with the underground construction operation that can reactivate seismogenic features nearby the future location of emplacement tunnels. Here we present numerical simulation aimed at understanding the potential for inducing seismicity during tunnel construction. The stress changes and their evolution during the excavation are evaluated with a finite element solver (FLAC3d). A strain-softening friction model is then used to simulate the occurrence of a sudden slip on a fault zone (if critical conditions for reactivation are reached). We also present a sensitivity analysis of the potential for inducing different seismic events by different tunnel sizes at varying distance from a nearby failure plane, with the final purpose of evaluating safety of a potential nuclear repository site on the short- and long-term.

  19. Longitudinal soliton tunneling in optical fiber.

    Science.gov (United States)

    Marest, T; Braud, F; Conforti, M; Wabnitz, S; Mussot, A; Kudlinski, A

    2017-06-15

    We report the observation of the longitudinal soliton tunneling effect in axially varying optical fibers. A fundamental soliton, initially propagating in the anomalous dispersion region of a fiber, can pass through a normal dispersion barrier without being substantially affected. We perform experimental studies by means of spectral and temporal characterizations that show the evidence of the longitudinal soliton tunneling process. Our results are well supported by numerical simulations using the generalized nonlinear Schrödinger equation.

  20. Geology of Pletovarje motorway tunnel (Slovenia

    Directory of Open Access Journals (Sweden)

    Magda Čarman

    2009-06-01

    Full Text Available Styrian motorway crosses the Pletovarje ridge through the tunnel having the same name. It intersects the mosteastern extension of the Southern Karavanke tectonic unit. Considering geological conditions, the tunnel couldbe divided into three sections: the inner Donat / Dona~ka fault zone composed of tectonic lenses of differentlithostratigraphic units (of paleozoic, triassic and tertiary age, massive dolomite (lower triassic and Smrekovecseries of oligocene age. Main faults have east – west direction and are subvertical.

  1. [Carpal tunnel syndrome in handicraft planning].

    Science.gov (United States)

    Bancone, C; Leghissa, P; Santini, M; Cologni, G; Bacis, M; Mosconi, G

    2007-01-01

    The purpose of this study is to assess the prevalence of carpal tunnel syndrome (CTS) in a group of bakers and to evaluate the presence of a biomechanical risk for upper limbs in the technological cycle. Health assessment (history, clinical examination, upper limbs electromyography) and risk evaluation through Check List OCRA (Occupational Repetitive Actions - Colombini / Occhipinti) have confirmed the initial hypothesis, placing this profession between those at risk for carpal tunnel syndrome.

  2. Spin Tunneling in a Rotating Nanomagnet

    Science.gov (United States)

    O'Keeffe, Michael; Chudnovsky, Eugene; Lehman College Theoretical Condensed Matter Physics Team

    2011-03-01

    We study spin tunneling in a magnetic nanoparticle with biaxial anisotropy that is free to rotate about its anisotropy axis. Exact instanton of the coupled equations of motion is found that connects degenerate classical energy minima. We show that mechanical freedom of the particle renormalizes magnetic anisotropy and increases the tunnel splitting. M. F. O'Keeffe and E. M. Chudnovsky, cond-mat, arXiv:1011.3134.

  3. Work on a transfer tunnel access shaft

    CERN Multimedia

    Laurent Guiraud

    2000-01-01

    Civil engineers work on one of the access shafts from the SPS to the LHC transfer tunnel, which will allow components and equipment to be lowered directly so that minimal transport is required. The transfer tunnel will take a proton beam from the SPS pre-accelerator and inject it into the clockwise circulating ring in the LHC where the beam will be accelerated to a final energy of 7 TeV.

  4. Nonlinear earthquake behaviour of highway tunnels

    Directory of Open Access Journals (Sweden)

    B. Sevim

    2011-10-01

    Full Text Available This paper describes the Arhavi Highway Tunnel which has two tubes, its geometrical properties, finite element model, and the nonlinear earthquake behaviour under a huge ground motion considering soil-structure interaction. The Arhavi Highway Tunnel is one of the tallest tunnels constructed in the Black Sea region of Turkey as part of the Coast Road Project. The tunnel has two tubes and each of them is about 1000 m tall. In the study, the modal analyses of the tunnel considering soil-structure interaction are performed and natural frequencies and mode shapes are obtained. Then, nonlinear transient analysis of the tunnel using Drucker-Prager criteria is performed applying acceleration components of 1992 Erzincan, Turkey earthquake's ground motion. In the time history analyses, Rayleigh damping coefficients are calculated using main natural frequency obtained from modal analysis. Element matrices are computed using the Gauss numerical integration technique. The Newmark method is used in the solution of the equation of motion. Because too much memory for the analyses is required, the first 7.5 s of the ground motions, which is the most effective duration, is taken into account in calculations. The displacement and stress results are observed to be the allowable level of the concrete material.

  5. Outcome of open carpal tunnel release surgery

    International Nuclear Information System (INIS)

    Khan, A.A.; Ali, H.; Muhammad, G.; Gul, N.; Zardan, K.K.; Mushtaq, M.; Ali, S.; Bhatti, S.N.; Ali, K.; Rashid, B.; Saboor, A.

    2015-01-01

    Background: Carpel tunnel syndrome is a common compression neuropathy of the median nerve causing pain, numbness and functional dysfunction of the hand. Among the available treatments, surgical release of the nerve is the most effective and acceptable treatment option. The aim of this study was to see the outcomes of surgical release of carpel tunnel using open technique. Method: This descriptive case series was conducted at the Department of neurosurgery, Ayub Teaching Hospital Abbottabad from April 2013 to March 2014. One hundred consecutive patients with carpel tunnel syndrome were included who underwent open carpel tunnel release surgery. They were followed up at 1, 3 and 6 months. Residual pain, numbness and functional improvement of the hand were the main outcome measures. Results: Out of 100 patients, 19 were males. The age ranged from 32 to 50 years with a mean of 39.29±3.99 years. The duration of symptoms was from 5 to 24 months. In the entire series patient functional outcome and satisfaction was 82 percentage at 1 month, 94 percentage at 3 months and 97 percentage at 6 months. 18 percentage patient had residual pain at 1 month post-operative follow-up, 6percentage at 3 months and 3 percentage at 6 month follow-up. Conclusion: Open carpel tunnel release surgery is an effective procedure for compression neuropathy of the median nerve. It should be offered to all patients with moderate to severe pain and functional disability related to carpel tunnel syndrome. (author)

  6. Quantum tunneling of magnetization in solids

    International Nuclear Information System (INIS)

    Stamp, P.C.E.; Barbara, B.

    1992-01-01

    Magnetic solids should, under certain circumstances, show macroscopic quantum behavior, in which coherence exists between completely distinct magnetization states, each involving a very large number of spins (∼10 12 spins). This article reviews the recent work in this field, concentrating particularly on macroscopic quantum tunneling (MQT) of magnetization. The two main phenomena discussed are the tunneling of magnetization in single-domain particles or grains (in which some 10 3 - 10 4 spins rotate together through an energy barrier), and the tunneling of domain walls in films or in bulk magnets; where walls containing ∼10 10 spins may tunnel off a pinning potential, or from one pinning center to another. Some attention is also given to the quantum nucleation of magnetization reversal in a bulk magnet, and to the quantum motion of other magnetic solitons (such as vortices). After a thorough analysis of the basic grain and wall tunneling phenomena, the authors continue on to a discussion of the various dissipative or decoherence mechanisms, which destroy the phase correlations involved in tunneling. The coupling of grain magnetization to phonons, photons, and electrons is shown to have little consequence for weakly-conducting or insulating grains. Domain walls couple to these and also to magnons and impurities or defects; the 3rd order coupling to magnons can have serious effects, but if one uses pure insulators at low temperatures, these can also be ignored

  7. Noise measurement in wind tunnels, workshop summary

    Science.gov (United States)

    Hickley, D. H.; Williams, J.

    1982-09-01

    In reviewing the progress made in acoustic measurements in wind tunnels over the 5-yr span of the workshops, it is evident that a great deal of progress has occurred. Specialized facilities are now on line, special measurement techniques were developed, and corrections were devised and proven. This capability is in the process of creating a new and more correct data bank on acoustic phenomena, and represents a major step forward in acoustics technology. Additional work is still required, but now, rather than concentrating on facilities and techniques, researchers may more profitably concentrate on noise-source modeling, with the simulation of propulsor noise source (in flight) and of propulsor/airframe airflow characteristics. Promising developments in directional acoustic receivers and other discrimination/correlation techniques should now be regularly exploited, in part for model noise-source diagnosis, but also to expedite extraction of the lone source signal from any residual background noise and reverberation in the working chamber and from parasitic noise due to essential rigs or instrumentation inside the airstream.

  8. Hydrogen Tunneling in Enzymes and Biomimetic Models

    Energy Technology Data Exchange (ETDEWEB)

    Layfield, Joshua P.; Hammes-Schiffer, Sharon

    2014-04-09

    Hydrogen transfer reactions play an important role throughout chemistry and biology. In general, hydrogen transfer reactions encompass proton and hydride transfer, which are associated with the transfer of a positively or negatively charged species, respectively, and proton-coupled electron transfer (PCET), which corresponds to the net transfer of one electron and one proton in the simplest case. Such PCET reactions can occur by either a sequential mechanism, in which the proton or electron transfers first, or a concerted mechanism, in which the electron and proton transfer in a single kinetic step with no stable intermediate. Furthermore, concerted PCET reactions can be subdivided into hydrogen atom transfer (HAT), which corresponds to the transfer of an electron and proton between the same donor and acceptor (i.e., the transfer of a predominantly neutral species), and electron-proton transfer (EPT), which corresponds to the transfer of an electron and proton between different donors and acceptors, possibly even in different directions. In all of these types of hydrogen transfer reactions, hydrogen tunneling could potentially play a significant role. The biomimetic portion was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

  9. Hydrogen Tunneling in Enzymes and Biomimetic Models

    Energy Technology Data Exchange (ETDEWEB)

    Layfield, Joshua P.; Hammes-Schiffer, Sharon

    2013-12-20

    Hydrogen transfer reactions play an important role throughout chemistry and biology. In general, hydrogen transfer reactions encompass proton and hydride transfer, which are associated with the transfer of a positively or negatively charged species, respectively, and proton-coupled electron transfer (PCET), which corresponds to the net transfer of one electron and one proton in the simplest case. Such PCET reactions can occur by either a sequential mechanism, in which the proton or electron transfers first, or a concerted mechanism, in which the electron and proton transfer in a single kinetic step with no stable intermediate. Furthermore, concerted PCET reactions can be subdivided into hydrogen atom transfer (HAT), which corresponds to the transfer of an electron and proton between the same donor and acceptor (i.e., the transfer of a predominantly neutral species), and electron-proton transfer (EPT), which corresponds to the transfer of an electron and proton between different donors and acceptors, possibly even in different directions. In all of these types of hydrogen transfer reactions, hydrogen tunneling could potentially play a signficant role. The theoretical development portion of this Review was supported by the National Science Foundation under CHE-10-57875. The biological portion of this Review was funded by NIH Grant No. GM056207. The biomimetic portion was supported as part of the Center for Molecular Electro-catalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

  10. Tunneling Nanotubes: Intimate Communication between Myeloid Cells

    Directory of Open Access Journals (Sweden)

    Maeva Dupont

    2018-01-01

    Full Text Available Tunneling nanotubes (TNT are dynamic connections between cells, which represent a novel route for cell-to-cell communication. A growing body of evidence points TNT towards a role for intercellular exchanges of signals, molecules, organelles, and pathogens, involving them in a diverse array of functions. TNT form among several cell types, including neuronal cells, epithelial cells, and almost all immune cells. In myeloid cells (e.g., macrophages, dendritic cells, and osteoclasts, intercellular communication via TNT contributes to their differentiation and immune functions. Importantly, TNT enable myeloid cells to communicate with a targeted neighboring or distant cell, as well as with other cell types, therefore creating a complex variety of cellular exchanges. TNT also contribute to pathogen spread as they serve as “corridors” from a cell to another. Herein, we addressed the complexity of the definition and in vitro characterization of TNT in innate immune cells, the different processes involved in their formation, and their relevance in vivo. We also assess our current understanding of how TNT participate in immune surveillance and the spread of pathogens, with a particular interest for HIV-1. Overall, despite recent progress in this growing research field, we highlight that further investigation is needed to better unveil the role of TNT in both physiological and pathological conditions.

  11. Organic tunnel field effect transistors

    KAUST Repository

    Tietze, Max Lutz

    2017-06-29

    Various examples are provided for organic tunnel field effect transistors (OTFET), and methods thereof. In one example, an OTFET includes a first intrinsic layer (i-layer) of organic semiconductor material disposed over a gate insulating layer; source (or drain) contact stacks disposed on portions of the first i-layer; a second i-layer of organic semiconductor material disposed on the first i-layer surrounding the source (or drain) contact stacks; an n-doped organic semiconductor layer disposed on the second i-layer; and a drain (or source) contact layer disposed on the n-doped organic semiconductor layer. The source (or drain) contact stacks can include a p-doped injection layer, a source (or drain) contact layer, and a contact insulating layer. In another example, a method includes disposing a first i-layer over a gate insulating layer; forming source or drain contact stacks; and disposing a second i-layer, an n-doped organic semiconductor layer, and a drain or source contact.

  12. Tunnel boring waste test plan

    International Nuclear Information System (INIS)

    Patricio, J.G.

    1984-03-01

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

  13. Tunneling and Transport in Nanowires

    International Nuclear Information System (INIS)

    Goldman, Allen M.

    2016-01-01

    The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO 3 . The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

  14. Tunneling and Transport in Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, Allen M. [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-08-16

    The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO3. The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

  15. Coherence in Magnetic Quantum Tunneling

    Science.gov (United States)

    Fernandez, Julio F.

    2001-03-01

    Crystals of single molecule magnets such as Mn_12 and Fe8 behave at low temperatures as a collection of independent spins. Magnetic anisotropy barriers slow down spin-flip processes. Their rate Γ becomes temperature independent at sufficiently low temperature. Quantum tunneling (QT) accounts for this behavior. Currently, spin QT in Mn_12 and Fe8 is assumed to proceed as an incoherent sum of small probability increments that occur whenever a bias field h(t) (arising from hyperfine interactions with nuclear spins) that varies with time t becomes sufficiently small, as in Landau-Zener transitions. Within a two-state model, we study the behavior of a suitably defined coherence time τ_φ and compare it with the correlation time τh for h(t). It turns out that τ_φ >τ_h, when τ_hδ h < hbar, where δ h is the rms deviation of h. We show what effect such coherence has on Γ. Its dependence on a static longitudinal applied field Hz is drastically affected. There is however no effect if the field is swept through resonance.

  16. Le LHC, un tunnel cosmique

    CERN Document Server

    CERN. Geneva

    2009-01-01

    Et si la lumière au bout du tunnel du LHC était cosmique ? En d’autres termes, qu’est-ce que le LHC peut nous apporter dans la connaissance de l’Univers ? Car la montée en énergie des accélérateurs de particules nous permet de mieux appréhender l’univers primordial, chaud et dense. Mais dans quel sens dit-on que le LHC reproduit des conditions proches du Big bang ? Quelles informations nous apporte-t-il sur le contenu de l’Univers ? La matière noire est-elle détectable au LHC ? L’énergie noire ? Pourquoi l’antimatière accumulée au CERN est-elle si rare dans l’Univers ? Et si le CERN a bâti sa réputation sur l’exploration des forces faibles et fortes qui opèrent au sein des atomes et de leurs noyaux, est-ce que le LHC peut nous apporter des informations sur la force gravitationnelle qui gouverne l’évolution cosmique ? Depuis une trentaine d’années, notre compréhension de l’univers dans ses plus grandes dimensions et l’appréhension de son comportement aux plus peti...

  17. Analysis of the performance of the drive system and diffuser of the Langley unitary plan wind tunnel

    Science.gov (United States)

    Hasel, L. E.; Stallings, R. L.

    1981-01-01

    A broad program was initiated at the Langley Research Center in 1973 to reduce the energy consumption of the laboratory. As a part of this program, the performance characteristics of the Unitary Plan Wind Tunnel were reexamined to determine if potential methods for incresing the operating efficiencies of the tunnel could be formulated. The results of that study are summarized. The performance characteristics of the drive system components and the variable-geometry diffuser system of the tunnel are documented and analyzed. Several potential methods for reducing the energy requirements of the facility are discussed.

  18. Research

    African Journals Online (AJOL)

    abp

    2015-09-09

    Sep 9, 2015 ... Orthopaedics and Traumatology, Faculty of Medicine, Adiyaman University, 02040 Adiyaman, Turkey,3Department of Orthopedics and. Traumatology, Umraniye Research and Education Hospital, 34899 Istanbul, Turkey, 4Department of Orthopedics and Traumatology, Umraniye. Research and Education ...

  19. Fabrication of magnetic tunnel junctions with a single-crystalline LiF tunnel barrier

    Science.gov (United States)

    Krishna Narayananellore, Sai; Doko, Naoki; Matsuo, Norihiro; Saito, Hidekazu; Yuasa, Shinji

    2018-04-01

    We fabricated Fe/LiF/Fe magnetic tunnel junctions (MTJs) by molecular beam epitaxy on a MgO(001) substrate, where LiF is an insulating tunnel barrier with the same crystal structure as MgO (rock-salt type). Crystallographical studies such as transmission electron microscopy and nanobeam electron diffraction observations revealed that the LiF tunnel barrier is single-crystalline and has a LiF(001)[100] ∥ bottom Fe(001)[110] crystal orientation, which is constructed in the same manner as MgO(001) on Fe(001). Also, the in-plane lattice mismatch between the LiF tunnel barrier and the Fe bottom electrode was estimated to be small (about 0.5%). Despite such advantages for the tunnel barrier of the MTJ, the observed tunnel magnetoresistance (MR) ratio was low (˜6% at 20 K) and showed a significant decrease with increasing temperature (˜1% at room temperature). The results imply that indirect tunneling and/or thermally excited carriers in the LiF tunnel barrier, in which the current basically is not spin-polarized, play a major role in electrical transport in the MTJ.

  20. Does flexible tunnel drilling affect the femoral tunnel angle measurement after anterior cruciate ligament reconstruction?

    Science.gov (United States)

    Muller, Bart; Hofbauer, Marcus; Atte, Akere; van Dijk, C Niek; Fu, Freddie H

    2015-12-01

    To quantify the mean difference in femoral tunnel angle (FTA) as measured on knee radiographs between rigid and flexible tunnel drilling after anatomic anterior cruciate ligament (ACL) reconstruction. Fifty consecutive patients that underwent primary anatomic ACL reconstruction with a single femoral tunnel drilled with a flexible reamer were included in this study. The control group was comprised of 50 patients all of who underwent primary anatomic ACL reconstruction with a single femoral tunnel drilled with a rigid reamer. All femoral tunnels were drilled through a medial portal to ensure anatomic tunnel placement. The FTA was determined from post-operative anterior-to-posterior (AP) radiographs by two independent observers. A 5° difference between the two mean FTA was considered clinically significant. The average FTA, when drilled with a rigid reamer, was 42.0° ± 7.2°. Drilling with a flexible reamer resulted in a mean FTA of 44.7° ± 7.0°. The mean difference of 2.7° was not statistically significant. The intraclass correlation coefficient for inter-tester reliability was 0.895. The FTA can be reliably determined from post-operative AP radiographs and provides a useful and reproducible metric for characterizing femoral tunnel position after both rigid and flexible femoral tunnel drilling. This has implications for post-operative evaluation and preoperative treatment planning for ACL revision surgery. IV.

  1. The significance of ultrasonographic carpal tunnel outlet measurements in the diagnosis of carpal tunnel syndrome.

    Science.gov (United States)

    Csillik, Anita; Bereczki, Dániel; Bora, László; Arányi, Zsuzsanna

    2016-12-01

    A retrospective study to investigate the utility of ultrasonographic carpal tunnel outlet measurements in the diagnosis of carpal tunnel syndrome (CTS). 118 hands of 87 patients with electrophysiologically confirmed CTS and 44 control hands of 23 subjects were assessed. Cross-sectional areas (CSA) of the median nerve were measured at the tunnel inlet, outlet, and forearm. Longitudinal diameters (LAPD) were measured at the inlet, proximal tunnel, distal tunnel, and outlet. CSA at the outlet (median: 18mm 2 ) and its palm-to-forearm-ratio (median: 2.7) were significantly larger than CSA at the inlet (median: 15mm 2 ) and its wrist-to-forearm-ratio (median: 2.2) (poutlet versus 13% only at the inlet. LAPD jump was significantly greater, suggesting relief of higher pressure, at the outlet/distal tunnel versus inlet/proximal tunnel (poutlet than at the inlet. We postulate that this is explained by the progressive increase of pressure within the tunnel from proximal to distal. The addition of CSA outlet measurements to inlet measurements increased CTS ultrasonographic diagnostic sensitivity and accuracy by 15% and 10%, respectively. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  2. Research

    African Journals Online (AJOL)

    The research methodology module was reviewed as part of the overall revision of the undergraduate physiotherapy curriculum of ... Structuring the research methodology module using an EBP teaching framework prepares students to formulate a research question, effectively ... manage, and organise bibliographic citations.

  3. Research

    African Journals Online (AJOL)

    ebutamanya

    2015-05-13

    May 13, 2015 ... Systems (SEEDS)-INDEPTH Network Accra, Ghana, 3KEMRI/Wellcome Trust Research Programme, The Centre of Geographical Medicine Research-. Coast, Kilifi, Kenya, 4Population Health Sciences/Research Support Unit, Faculty of Health Sciences, Aga Khan University- East Africa, Nairobi,. Kenya ...

  4. Research

    African Journals Online (AJOL)

    research process, as part of which students must find and appraise evidence from research.[5] This highlights that teaching research methodology is inclined towards equipping students ... Students believed that evidence-based practice was vital, yet their understanding of the concept was restricted when compared with the.

  5. Research

    African Journals Online (AJOL)

    ebutamanya

    2015-03-02

    Mar 2, 2015 ... this program provided short-term and long-term research training to. US infectious disease fellows who would work on collaborative research projects with Kenyan trainees. Since the program began in. 1988, there have been 56 US trainees, and 13 of these continue to collaborate with Kenyan researchers.

  6. Airborne asbestos fibres monitoring in tunnel excavation.

    Science.gov (United States)

    Gaggero, Laura; Sanguineti, Elisa; Yus González, Adrián; Militello, Gaia Maria; Scuderi, Alberto; Parisi, Giovanni

    2017-07-01

    Tunnelling across ophiolitic formation with Naturally Occurring Asbestos (NOA) can release fibres into the environment, exposing workers, and the population, if fibres spread outside the tunnel, leading to increased risk of developing asbestos-related disease. Therefore, a careful plan of environmental monitoring is carried out during Terzo Valico tunnel excavation. In the present study, data of 1571 samples of airborne dust, collected between 2014 and 2016 inside the tunnels, and analyzed by SEM-EDS for quantification of workers exposure, are discussed. In particular, the engineering and monitoring management of 100 m tunnelling excavation across a serpentinite lens (Cravasco adit), intercalated within calcschists, is reported. At this chrysotile occurrence, 84% of 128 analyzed samples (from the zone closer to the front rock) were above 2 ff/l. However, thanks to safety measures implemented and tunnel compartmentation in zones, the asbestos fibre concentration did not exceed the Italian standard of occupational exposure (100 ff/l) and 100% of samples collected in the outdoor square were below 1 ff/l. During excavation under normal working conditions, asbestos concentrations were below 2 ff/l in 97.4% of the 668 analyzed samples. Our results showed that air monitoring can objectively confirm the presence of asbestos minerals at a rock front in relative short time and provide information about the nature of the lithology at the front. The present dataset, the engineering measures described and the operative conclusions are liable to support the improvement of legislation on workers exposure to asbestos referred to the tunnelling sector, lacking at present. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. A Method for Dynamic Risk Assessment and Management of Rockbursts in Drill and Blast Tunnels

    Science.gov (United States)

    Liu, Guo-Feng; Feng, Xia-Ting; Feng, Guang-Liang; Chen, Bing-Rui; Chen, Dong-Fang; Duan, Shu-Qian

    2016-08-01

    Focusing on the problems caused by rockburst hazards in deep tunnels, such as casualties, damage to construction equipment and facilities, construction schedule delays, and project cost increase, this research attempts to present a methodology for dynamic risk assessment and management of rockbursts in D&B tunnels. The basic idea of dynamic risk assessment and management of rockbursts is determined, and methods associated with each step in the rockburst risk assessment and management process are given, respectively. Among them, the main parts include a microseismic method for early warning the occurrence probability of rockburst risk, an estimation method that aims to assess potential consequences of rockburst risk, an evaluation method that utilizes a new quantitative index considering both occurrence probability and consequences for determining the level of rockburst risk, and the dynamic updating. Specifically, this research briefly describes the referenced microseismic method of warning rockburst, but focuses on the analysis of consequences and associated risk assessment and management of rockburst. Using the proposed method of risk assessment and management of rockburst, the occurrence probability, potential consequences, and the level of rockburst risk can be obtained in real-time during tunnel excavation, which contributes to the dynamic optimisation of risk mitigation measures and their application. The applicability of the proposed method has been verified by those cases from the Jinping II deep headrace and water drainage tunnels at depths of 1900-2525 m (with a length of 11.6 km in total for D&B tunnels).

  8. Airloads Correlation of the UH-60A Rotor Inside the 40- by 80-Foot Wind Tunnel

    Science.gov (United States)

    Chang, I-Chung; Norman, Thomas R.; Romander, Ethan A.

    2013-01-01

    The presented research validates the capability of a loosely-coupled computational fluid dynamics (CFD) and comprehensive rotorcraft analysis (CRA) code to calculate the flowfield around a rotor and test stand mounted inside a wind tunnel. The CFD/CRA predictions for the full-scale UH-60A Airloads Rotor inside the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel at NASA Ames Research Center are compared with the latest measured airloads and performance data. The studied conditions include a speed sweep at constant lift up to an advance ratio of 0.4 and a thrust sweep at constant speed up to and including stall. For the speed sweep, wind tunnel modeling becomes important at advance ratios greater than 0.37 and test stand modeling becomes increasingly important as the advance ratio increases. For the thrust sweep, both the wind tunnel and test stand modeling become important as the rotor approaches stall. Despite the beneficial effects of modeling the wind tunnel and test stand, the new models do not completely resolve the current airload discrepancies between prediction and experiment.

  9. Pioneering Russian wind tunnels and first experimental investigations, 1871-1915

    Science.gov (United States)

    Gorbushin, A. R.

    2017-11-01

    A review of foreign and Russian sources is given mentioning the pioneering wind tunnels built in Russia at the turn of 19th and 20th centuries. The first wind tunnel in Russia was constructed by V.A. Pashkevich at the Mikhailovsky Artillery Academy in St. Petersburg in 1871. In total from 1871 through 1915, 18 wind tunnels were constructed in Russia: 11 in Moscow, 5 in St. Petersburg and 2 in Kaluga. An overview of the pioneering Russian wind tunnels built by V.A. Pashkevich, K.E. Tsiolkovsky, prof. N.E. Zhukovsky, D.P. Ryabushinsky and prof. K.P. Boklevsky is given. Schemes, photographs, formulas, description of the research and test results taken from the original papers published by the wind tunnel designers are given. Photographs from the N.E. Zhukovsky Scientific and Memorial Museum and the Archive of the Russian Academy of Sciences are used in the article. Methods of flow visualization and results of their application are presented. The Russian scientists and researchers' contribution to the development of techniques and methods of aerodynamic experiment is shown, including one of the most important aspects - the wall interference problem.

  10. Airloads Correlation of the UH-60A Rotor inside the 40- by 80-Foot Wind Tunnel

    Directory of Open Access Journals (Sweden)

    I-Chung Chang

    2014-01-01

    Full Text Available The presented research validates the capability of a loosely coupled computational fluid dynamics (CFD and comprehensive rotorcraft analysis (CRA code to calculate the flowfield around a rotor and test stand mounted inside a wind tunnel. The CFD/CRA predictions for the Full-Scale UH-60A Airloads Rotor inside the National Full-Scale Aerodynamics Complex (NFAC 40- by 80-Foot Wind Tunnel at NASA Ames Research Center are compared with the latest measured airloads and performance data. The studied conditions include a speed sweep at constant lift up to an advance ratio of 0.4 and a thrust sweep at constant speed up to and including stall. For the speed sweep, wind tunnel modeling becomes important at advance ratios greater than 0.37 and test stand modeling becomes increasingly important as the advance ratio increases. For the thrust sweep, both the wind tunnel and test stand modeling become important as the rotor approaches stall. Despite the beneficial effects of modeling the wind tunnel and test stand, the new models do not completely resolve the current airload discrepancies between prediction and experiment.

  11. Investing American Recovery and Reinvestment Act Funds to Advance Capability, Reliability, and Performance in NASA Wind Tunnels

    Science.gov (United States)

    Sydnor, Goerge H.

    2010-01-01

    The National Aeronautics and Space Administration's (NASA) Aeronautics Test Program (ATP) is implementing five significant ground-based test facility projects across the nation with funding provided by the American Recovery and Reinvestment Act (ARRA). The projects were selected as the best candidates within the constraints of the ARRA and the strategic plan of ATP. They are a combination of much-needed large scale maintenance, reliability, and system upgrades plus creating new test beds for upcoming research programs. The projects are: 1.) Re-activation of a large compressor to provide a second source for compressed air and vacuum to the Unitary Plan Wind Tunnel at the Ames Research Center (ARC) 2.) Addition of high-altitude ice crystal generation at the Glenn Research Center Propulsion Systems Laboratory Test Cell 3, 3.) New refrigeration system and tunnel heat exchanger for the Icing Research Tunnel at the Glenn Research Center, 4.) Technical viability improvements for the National Transonic Facility at the Langley Research Center, and 5.) Modifications to conduct Environmentally Responsible Aviation and Rotorcraft research at the 14 x 22 Subsonic Tunnel at Langley Research Center. The selection rationale, problem statement, and technical solution summary for each project is given here. The benefits and challenges of the ARRA funded projects are discussed. Indirectly, this opportunity provides the advantages of developing experience in NASA's workforce in large projects and maintaining corporate knowledge in that very unique capability. It is envisioned that improved facilities will attract a larger user base and capabilities that are needed for current and future research efforts will offer revenue growth and future operations stability. Several of the chosen projects will maximize wind tunnel reliability and maintainability by using newer, proven technologies in place of older and obsolete equipment and processes. The projects will meet NASA's goal of

  12. Design of Intelligent Power Supply System for Expressway Tunnel

    Science.gov (United States)

    Wang, Li; Li, Yutong; Lin, Zimian

    2018-01-01

    Tunnel lighting program is one of the key points of tunnel infrastructure construction. As tunnels tend to handle remote locations, power supply line construction generally has been having the distance, investment, high cost characteristics. To solve this problem, we propose a green, environmentally friendly, energy-efficient lighting system. This program uses the piston-wind which cars within tunnel produce as the power and combines with solar energy, physical lighting to achieve it, which solves the problem of difficult and high cost of highway tunnel section, and provides new ideas for the future construction of tunnel power supply.

  13. Application fo tunneling and atomic force detection to machines and scientific instruments. Tunnel gensho ya genshikan no mechatronics eno oyo

    Energy Technology Data Exchange (ETDEWEB)

    Kawakatsu, H. (The University of Tokyo, Tokyo (Japan). Institute of Industrial Science)

    1991-11-01

    It is now about ten years since the scanning tunnel microscope (STM) and the atomic force microscope (AFM) were invented. These microscopes are used very importantly today as a surface analyzer capable of atomic order analysis for their very high resolution. The STM and AFM obtain images of atomic orders by means of mechanical scanning of the probes. This means that the microscopes can control positioning, force detection and displacement in regions of sub-nanometer orders. Examples of researches may include detection of acceleration, length measurement, positioning, force detection, nano-tripology, processing and gravitational wave detection. As described above, this paper notes the researches derived from the operational principles of the STM and AFM, rather than the researches on the observation objects. The great diversity of the researches taken up and the greatness in the number of researches in the STM and AFM gather how superbly germinative these were. 34 refs.

  14. Lorentz Invariance Violation and Modified Hawking Fermions Tunneling Radiation

    Directory of Open Access Journals (Sweden)

    Shu-Zheng Yang

    2016-01-01

    Full Text Available Recently the modified Dirac equation with Lorentz invariance violation has been proposed, which would be helpful to resolve some issues in quantum gravity theory and high energy physics. In this paper, the modified Dirac equation has been generalized in curved spacetime, and then fermion tunneling of black holes is researched under this correctional Dirac field theory. We also use semiclassical approximation method to get correctional Hamilton-Jacobi equation, so that the correctional Hawking temperature and correctional black hole’s entropy are derived.

  15. Wind tunnel tests of a free yawing downwind wind turbine

    DEFF Research Database (Denmark)

    Verelst, David Robert; Larsen, Torben J.; van Wingerden, Jan-Willem

    2014-01-01

    . The discussed test cases show that the turbine is stable while operating in free yawing conditions. Further, the effect of the tower shadow passage on the blade flapwise strain measurement is evaluated. Finally, data from the experiment is compared with preliminary simulations using DTU Wind Energy......This research paper presents preliminary results on a behavioural study of a free yawing downwind wind turbine. A series of wind tunnel tests was performed at the TU Delft Open Jet Facility with a three bladed downwind wind turbine and a rotor radius of 0.8 meters. The setup includes an off...

  16. Huge tunnelling anisotropic magnetoresistance in (Ga,Mn)As nanoconstrictions

    Czech Academy of Sciences Publication Activity Database

    Giddings, A.D.; Makarovsky, O. N.; Khalid, M.N.; Yasin, S.; Edmonds, K. W.; Campion, R. P.; Wunderlich, J.; Jungwirth, Tomáš; Williams, D.A.; Gallagher, B. L.; Foxon, C. T.

    2008-01-01

    Roč. 10, č. 8 (2008), 085004/1-085004/9 ISSN 1367-2630 R&D Projects: GA ČR GEFON/06/E002; GA MŠk LC510; GA ČR GA202/05/0575; GA ČR GA202/04/1519 EU Projects: European Commission(XE) 015728 - NANOSPIN Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic semiconductor * nanoconstriction * tunneling anisotropic magnetoresistance , Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.440, year: 2008

  17. 3D Numerical Analysis of the Effects of an Advancing Tunnel on an Existing Loaded Pile Group

    Directory of Open Access Journals (Sweden)

    M. A. Soomro

    2018-02-01

    Full Text Available Tunnels are often preferred for underground transportation in densely populated areas. In these areas, it is almost inevitable for tunnels to run close to some existing pile foundations. Since tunnelling activities induce stress relief and soil movement in the ground, existing piles may suffer from additional axial and lateral forces, bending moments, settlements and lateral deflections. Most of the previous researches on the responses of pile foundations due to tunnel construction were carried out under the plane strain condition. In this paper, a three-dimensional, elasto-plastic and coupled-consolidation finite element parametric study has been carried out to investigate the effects of a 6 m open-face advancing tunnel on a two by two pile group in saturated stiff clay. The influence of different cover-to-diameter (C/D tunnel ratios (namely 2.0, 2.5 & 3.0 was studied. The objectives of this study are to determine the changes in axial load distribution, changes in shaft resistance along the shaft of pile group and settlement of pile cap due to an advancing open-face tunnel.

  18. Excavation damage zone tracer experiment in the floor of the room 415 test tunnel

    International Nuclear Information System (INIS)

    Frost, L.H.; Everitt, R.A.

    1997-03-01

    A 3.5-m-diameter test tunnel was constructed on the 420 Level of AECL's Underground Research Laboratory using a mechanical excavation technique. The orientation of the tunnel was chosen to maximize the stress ratio in the plane perpendicular to the tunnel axis in order to promote and study stress-induced excavation damage. The resulting excavation damage zone (EDZ) is characterized by a distinct breakout notch in both the floor and roof of the tunnel. In the floor of the tunnel, the main flow pathway within the EDZ is within a zone of intense grain-size fracturing (process zone) located at the tip of the breakout notch; virtually no flow occurs outside this region. A tracer experiment was performed within the EDZ in the floor of the tunnel to characterize the solute transport properties (permeability, transport porosity and dispersivity) within the process zone, as well as to develop and demonstrate methods for determining the transport properties within EDZs of underground tunnels. The experiment was performed as a constant head test by continuously injecting a constant concentration of iodide tracer into a region of the process zone, and by monitoring tracer breakthrough from the zone at a distance 1.5 m away. An equivalent-porous-media approach was taken in analysing fluid flow and solute transport through the process zone. Based on mass flux calculations, the hydraulic conductivity and transport porosity of the process zone are estimated to be 7.4 x 10 -7 m/s and 2.7 % respectively. Based on an analytic solution that represents tracer transport within the process zone as one-dimensional advective diffusive transport in a finite homogeneous porous medium, the longitudinal dispersivity and transport porosity of the zone are estimated to be 0.60 m and 3.3 % respectively. The transport porosity values estimated by both the mass flux and analytic calculations compare quite well. (author)

  19. Control of the NASA Langley 16-Foot Transonic Tunnel with the Self-Organizing Feature Map

    Science.gov (United States)

    Motter, Mark A.

    1998-01-01

    A predictive, multiple model control strategy is developed based on an ensemble of local linear models of the nonlinear system dynamics for a transonic wind tunnel. The local linear models are estimated directly from the weights of a Self Organizing Feature Map (SOFM). Local linear modeling of nonlinear autonomous systems with the SOFM is extended to a control framework where the modeled system is nonautonomous, driven by an exogenous input. This extension to a control framework is based on the consideration of a finite number of subregions in the control space. Multiple self organizing feature maps collectively model the global response of the wind tunnel to a finite set of representative prototype controls. These prototype controls partition the control space and incorporate experimental knowledge gained from decades of operation. Each SOFM models the combination of the tunnel with one of the representative controls, over the entire range of operation. The SOFM based linear models are used to predict the tunnel response to a larger family of control sequences which are clustered on the representative prototypes. The control sequence which corresponds to the prediction that best satisfies the requirements on the system output is applied as the external driving signal. Each SOFM provides a codebook representation of the tunnel dynamics corresponding to a prototype control. Different dynamic regimes are organized into topological neighborhoods where the adjacent entries in the codebook represent the minimization of a similarity metric which is the essence of the self organizing feature of the map. Thus, the SOFM is additionally employed to identify the local dynamical regime, and consequently implements a switching scheme than selects the best available model for the applied control. Experimental results of controlling the wind tunnel, with the proposed method, during operational runs where strict research requirements on the control of the Mach number were met, are

  20. Research

    African Journals Online (AJOL)

    abp

    2015-01-19

    Jan 19, 2015 ... in Cameroon. This study aimed at examining the sexual risk behaviours of high school female learners in Mbonge subdivision of rural Cameroon. ... Despite a wealth of research on youth, little research has been done on the sexual ..... Behavior, and Mental Health: a study of University Students in. Uganda.