WorldWideScience

Sample records for high speed flows

  1. Wake flow characteristics at high wind speed

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge; Larsen, Torben J.; Larsen, Gunner Chr.

    2016-01-01

    Wake flow characteristic at high wind speeds is the main subject of this paper. Although the wake losses decrease at high wind speeds it has been found in a recent study that for multiple wake inflow the increase in loading due to wake effects are substantial even at wind speeds well above rated ...

  2. Compressibility, turbulence and high speed flow

    CERN Document Server

    Gatski, Thomas B

    2013-01-01

    Compressibility, Turbulence and High Speed Flow introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range, through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. The book provides the reader with the necessary background and current trends in the theoretical and experimental aspects of compressible turbulent flows and compressible turbulence. Detailed derivations of the pertinent equations describing the motion of such turbulent flows is provided and an extensive discussion of the various approaches used in predicting both free shear and wall bounded flows is presented. Experimental measurement techniques common to the compressible flow regime are introduced with particular emphasis on the unique challenges presented by high speed flows. Both experimental and numerical simulation work is supplied throughout to provide the reader with an overall perspective of current tre...

  3. Investigations on high speed MHD liquid flow

    International Nuclear Information System (INIS)

    Yamasaki, Takasuke; Kamiyama, Shin-ichi.

    1982-01-01

    Lately, the pressure drop problem of MHD two-phase flow in a duct has been investigated theoretically and experimentally in conjunction with the problems of liquid metal MHD two-phase flow power-generating cycle or of liquid metal boiling two-phase flow in the blanket of a nuclear fusion reactor. Though many research results have been reported so far for MHD single-phase flow, the hydrodynamic studies on high speed two-phase flow are reported only rarely, specifically the study dealing with the generation of cavitation is not found. In the present investigation, the basic equation was derived, analyzing the high speed MHD liquid flow in a diverging duct as the one-dimensional flow of homogeneous two-phase fluid of small void ratio. Furthermore, the theoretical solution for the effect of magnetic field on cavitation-generating conditions was tried. The pressure distribution in MHD flow in a duct largely varies with load factor, and even if the void ratio is small, the pressure distribution in two-phase flow is considerably different from that in single-phase flow. Even if the MHD two-phase flow in a duct is subsonic flow at the throat, the critical conditions may be achieved sometimes in a diverging duct. It was shown that cavitation is more likely to occur as magnetic field becomes more intense if it is generated downstream of the throat. This explains the experimental results qualitatively. (Wakatsuki, Y.)

  4. Compressibility, turbulence and high speed flow

    CERN Document Server

    Gatski, Thomas B

    2009-01-01

    This book introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. For the computation of turbulent compressible flows, current methods of averaging and filtering are presented so that the reader is exposed to a consistent development of applicable equation sets for both the mean or resolved fields as well as the transport equations for the turbulent stress field. For the measurement of turbulent compressible flows, current techniques ranging from hot-wire anemometry to PIV are evaluated and limitations assessed. Characterizing dynamic features of free shear flows, including jets, mixing layers and wakes, and wall-bounded flows, including shock-turbulence and shock boundary-layer interactions, obtained from computations, experiments and simulations are discussed. Key features: * Describes prediction methodologies in...

  5. Rat muscle blood flows during high-speed locomotion

    International Nuclear Information System (INIS)

    Armstrong, R.B.; Laughlin, M.H.

    1985-01-01

    We previously studied blood flow distribution within and among rat muscles as a function of speed from walking (15 m/min) through galloping (75 m/min) on a motor-driven treadmill. The results showed that muscle blood flows continued to increase as a function of speed through 75 m/min. The purpose of the present study was to have rats run up to maximal treadmill speeds to determine if blood flows in the muscles reach a plateau as a function of running speed over the animals normal range of locomotory speeds. Muscle blood flows were measured with radiolabeled microspheres at 1 min of running at 75, 90, and 105 m/min in male Sprague-Dawley rats. The data indicate that even at these relatively high treadmill speeds there was still no clear evidence of a plateau in blood flow in most of the hindlimb muscles. Flows in most muscles continued to increase as a function of speed. These observed patterns of blood flow vs. running speed may have resulted from the rigorous selection of rats that were capable of performing the high-intensity exercise and thus only be representative of a highly specific population of animals. On the other hand, the data could be interpreted to indicate that the cardiovascular potential during exercise is considerably higher in laboratory rats than has normally been assumed and that inadequate blood flow delivery to the muscles does not serve as a major limitation to their locomotory performance

  6. Modeling of high speed micro rotors in moderate flow confinement

    NARCIS (Netherlands)

    Dikmen, E.; van der Hoogt, Peter; Aarts, Ronald G.K.M.; Sas, P.; Bergen, B.

    2008-01-01

    The recent developments in high speed micro rotating machinery lead to the need for multiphysical modeling of the rotor and the surrounding medium. In this study, thermal and flow induced effects on rotor dynamics of geometries with moderate flow confinement are studied. The structure is modeled via

  7. High-speed solar wind flow parameters at 1 AU

    International Nuclear Information System (INIS)

    Feldman, W.C.; Asbridge, J.R.; Bame, S.J.; Gosling, J.T.

    1976-01-01

    To develop a set of constraints for theories of solar wind high-speed streams, a detailed study was made of the fastest streams observed at 1 AU during the time period spanning March 1971 through July 1974. Streams were accepted for study only if (1) the maximum speed exceeded 650 km s -1 ; (2) effects of stream-stream dynamical interaction on the flow parameters could be safely separated from the intrinsic characteristics of the high-speed regions; (3) the full width at half maximum (FWHM) of the stream when mapped back to 20 solar radii by using a constant speed approximation was greater than 45degree in Carrington longitude; and (4) there were no obvious solar-activity-induced contaminating effects. Nineteen streams during this time interval satisfied these criteria. Average parameters at 1 AU for those portions of these streams above V=650 km s -1 are given.Not only is it not presently known why electrons are significantly cooler than the protons within high-speed regions, but also observed particle fluxes and convected energy fluxes for speed greater than 650 km s -1 are substantially larger than those values predicted by any of the existing theories of solar wind high-speed streams. More work is therefore needed in refining present solar wind models to see whether suitable modifications and/or combinations of existing theories based on reasonable coronal conditions can accommodate the above high-speed flow parameters

  8. High speed digital holographic interferometry for hypersonic flow visualization

    Science.gov (United States)

    Hegde, G. M.; Jagdeesh, G.; Reddy, K. P. J.

    2013-06-01

    Optical imaging techniques have played a major role in understanding the flow dynamics of varieties of fluid flows, particularly in the study of hypersonic flows. Schlieren and shadowgraph techniques have been the flow diagnostic tools for the investigation of compressible flows since more than a century. However these techniques provide only the qualitative information about the flow field. Other optical techniques such as holographic interferometry and laser induced fluorescence (LIF) have been used extensively for extracting quantitative information about the high speed flows. In this paper we present the application of digital holographic interferometry (DHI) technique integrated with short duration hypersonic shock tunnel facility having 1 ms test time, for quantitative flow visualization. Dynamics of the flow fields in hypersonic/supersonic speeds around different test models is visualized with DHI using a high-speed digital camera (0.2 million fps). These visualization results are compared with schlieren visualization and CFD simulation results. Fringe analysis is carried out to estimate the density of the flow field.

  9. Plasma-Assisted Chemistry in High-Speed Flow

    International Nuclear Information System (INIS)

    Leonov, Sergey B.; Yarantsev, Dmitry A.; Napartovich, Anatoly P.; Kochetov, Igor V.

    2007-01-01

    Fundamental problems related to the high-speed combustion are analyzed. The result of plasma-chemical modeling is presented as a motivation of experimental activity. Numerical simulations of the effect of uniform non-equilibrium discharge on the premixed hydrogen and ethylene-air mixture in supersonic flow demonstrate an advantage of such a technique over a heating. Experimental results on multi-electrode non-uniform discharge maintenance behind wallstep and in cavity of supersonic flow are presented. The model test on hydrogen and ethylene ignition is demonstrated at direct fuel injection to low-temperature high-speed airflow

  10. High speed motion neutron radiography of two-phase flow

    International Nuclear Information System (INIS)

    Robinson, A.H.; Wang, S.L.

    1983-01-01

    Current research in the area of two-phase flow utilizes a wide variety of sensing devices, but some limitations exist on the information which can be obtained. Neutron radiography is a feasible alternative to ''see'' the two-phase flow. A system to perform neutron radiographic analysis of dynamic events which occur on the order of several milliseconds has been developed at Oregon State University. Two different methods have been used to radiograph the simulated two-phase flow. These are pulsed, or ''flash'' radiography, and high speed movie neutron radiography. The pulsed method serves as a ''snap-shot'' with an exposure time ranging from 10 to 20 milliseconds. In high speed movie radiography, a scintillator is used to convert neutrons into light which is enhanced by an optical intensifier and then photographed by a high speed camera. Both types of radiography utilize the pulsing capability of the OSU TRIGA reactor. The principle difficulty with this type of neutron radiography is the fogging of the image due to the large amount of scattering in the water. This difficulty can be overcome by using thin regions for the two-phase flow or using heavy water instead of light water. The results obtained in this paper demonstrate the feasibility of using neutron radiography to obtain data in two-phase flow situations. Both movies and flash radiographs have been obtained of air bubbles in water and boiling from a heater element. The neutron radiographs of the boiling element show both nucleate boiling and film boiling. (Auth.)

  11. Measurements of granular flow dynamics with high speed digital images

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jingeol [Univ. of Florida, Gainesville, FL (United States)

    1994-01-01

    The flow of granular materials is common to many industrial processes. This dissertation suggests and validates image processing algorithms applied to high speed digital images to measure the dynamics (velocity, temperature and volume fraction) of dry granular solids flowing down an inclined chute under the action of gravity. Glass and acrylic particles have been used as granular solids in the experiment. One technique utilizes block matching for spatially averaged velocity measurements of the glass particles. This technique is compared with the velocity measurement using an optic probe which is a conventional granular flow velocity measurement device. The other technique for measuring the velocities of individual acrylic particles is developed with correspondence using a Hopfield network. This technique first locates the positions of particles with pattern recognition techniques, followed by a clustering technique, which produces point patterns. Also, several techniques are compared for particle recognition: synthetic discriminant function (SDF), minimum average correlation energy (MACE) filter, modified minimum average correlation energy (MMACE) filter and variance normalized correlation. The author proposes an MMACE filter which improves generalization of the MACE filter by adjusting the amount of averaged spectrum of training images in the spectrum whitening stages of the MACE filter. Variance normalized correlation is applied to measure the velocity and temperature of flowing glass particles down the inclined chute. The measurements are taken for the steady and wavy flow and qualitatively compared with a theoretical model of granular flow.

  12. Transient flow characteristics of a high speed rotary valve

    Science.gov (United States)

    Browning, Patrick H.

    were experimentally mapped as a function of valve speed, inter-cylinder pressure ratios and volume ratios and the results were compared to compressible flow theoretical models. Specifically, the transient behavior suggested a short-lived loss-mode initiation closely resembled by shock tube theory followed by a quasi-steady flow regime resembling choked flow behavior. An empirical model was then employed to determine the useful range of the CCV design as applied to a four-stroke CIBAI engine cycle modeled using a 1-D quasi-steady numerical method, with particular emphasis on the cyclic timing of the CCV opening. Finally, a brief discussion of a high-temperature version of the CCV design is presented.

  13. High-Speed Thermal Characterization of Cryogenic Flows, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Luna proposes to continue development on a high-speed fiber optic sensor and readout system for cryogenic temperature measurements in liquid oxygen (LOX) and liquid...

  14. Dust mobilization by high-speed vapor flow under LOVA

    International Nuclear Information System (INIS)

    Matsuki, K.; Suzuki, S.; Ebara, S.; Yokomine, T.; Shimizu, A.

    2006-01-01

    In the safety analysis on the International Thermonuclear Experimental Reactor (ITER), the ingress of coolant (ICE) event and the loss of vacuum (LOVA) event are considered as one of the most serious accident. On the assumption of LOVA occurring after ICE, it is inferable that activated dusts are under the wet condition. Transport behavior of in-vessel activated dusts under the wet condition is not well understood in comparison with the dry case. In this study, we experimentally investigated the entrainment behavior of dust under LOVA after ICE. We measured dust entrainment by high-speed humid airflow with phase change. Graphite dusts and glass beads are used as substitutions for mobile inventory. The relations among the relative humidity, the entrainment of particles in the exhaust gas flow and the adhesion rate of dust particles on the pipe wall have been made clear, as has the distribution profile of dust deposition on the pipe wall. The entrainment ratio decreased as the relative humidity increased and increased as the initial pressure difference increased

  15. Flow visualization in models of high speed centrifugal separators

    International Nuclear Information System (INIS)

    Lagerstedt, T.; Nabo, O.

    1987-01-01

    The modern centrifugal separator is a fluid machine where the high ''G'' forces set up by rotation are utilized to separate phases of different densities. The fluid dynamics of the separator is complex and poorly known. Hundred years of (practical) experience has, however, turned the separator into an efficient machine. The present report shows how straight forward visualization experiments in model rigs provide valuable information on the flow inside the separator. The report concentrates on describing the flow between the closely spaced discs in a separator disc stack

  16. Turbulent Scalar Transport Model Validation for High Speed Propulsive Flows, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This effort entails the validation of a RANS turbulent scalar transport model (SFM) for high speed propulsive flows, using new experimental data sets and...

  17. PDF methods for combustion in high-speed turbulent flows

    Science.gov (United States)

    Pope, Stephen B.

    1995-01-01

    This report describes the research performed during the second year of this three-year project. The ultimate objective of the project is extend the applicability of probability density function (pdf) methods from incompressible to compressible turbulent reactive flows. As described in subsequent sections, progress has been made on: (1) formulation and modelling of pdf equations for compressible turbulence, in both homogeneous and inhomogeneous inert flows; and (2) implementation of the compressible model in various flow configurations, namely decaying isotropic turbulence, homogeneous shear flow and plane mixing layer.

  18. Particle deposition in low-speed, high-turbulence flows

    DEFF Research Database (Denmark)

    Reck, Mads; Larsen, Poul Scheel; Ullum, U.

    2002-01-01

    The experimental and numerical study considers the concentration of airborne particulate contaminants, such as spores of spoilage fungi, and their deposition on a surface, in a petri dish, and on a warm box-shaped product placed in a food-processing environment. Field measurements by standard...... field measurements. Particle deposition is shown to be associated with near-wall coherent structures. Flow reversal, simulated by impulsive start, is shown to give higher deposition rates than steady mean flows. Key word index: Spoilage fungi; spores; food processing plant; deposition flux; large eddy...

  19. High-speed cell recognition algorithm for ultrafast flow cytometer imaging system

    Science.gov (United States)

    Zhao, Wanyue; Wang, Chao; Chen, Hongwei; Chen, Minghua; Yang, Sigang

    2018-04-01

    An optical time-stretch flow imaging system enables high-throughput examination of cells/particles with unprecedented high speed and resolution. A significant amount of raw image data is produced. A high-speed cell recognition algorithm is, therefore, highly demanded to analyze large amounts of data efficiently. A high-speed cell recognition algorithm consisting of two-stage cascaded detection and Gaussian mixture model (GMM) classification is proposed. The first stage of detection extracts cell regions. The second stage integrates distance transform and the watershed algorithm to separate clustered cells. Finally, the cells detected are classified by GMM. We compared the performance of our algorithm with support vector machine. Results show that our algorithm increases the running speed by over 150% without sacrificing the recognition accuracy. This algorithm provides a promising solution for high-throughput and automated cell imaging and classification in the ultrafast flow cytometer imaging platform.

  20. Advancement and Application of Multi-Phase CFD Modeling to High Speed Supercavitating Flows

    Science.gov (United States)

    2013-08-13

    October 2008 - December 2013 4. TITLE AND SUBTITLE Advancement and Application of Multi-Phase CFD Modeling to High Speed Supercavitating Flows...influence cavity hysteresis behavior. These observations are used to guide improved supercavitating -vehicle analyses including numerical predictions...experiments, and modeling 15. SUBJECT TERMS supercavitation , computational fluid dynamics, multiphase flow 16. SECURITY CLASSIFICATION OF: a

  1. Cavitation performance improvement of high specific speed mixed-flow pump

    International Nuclear Information System (INIS)

    Chen, T; Sun, Y B; Wu, D Z; Wang, L Q

    2012-01-01

    Cavitation performance improvement of large hydraulic machinery such as pump and turbine has been a hot topic for decades. During the design process of the pumps, in order to minimize size, weight and cost centrifugal and mixed-flow pump impellers are required to operate at the highest possible rotational speed. The rotational speed is limited by the phenomenon of cavitation. The hydraulic model of high-speed mixed-flow pump with large flow rate and high pumping head, which was designed based on the traditional method, always involves poor cavitation performance. In this paper, on the basis of the same hydraulic design parameters, two hydraulic models of high-speed mixed-flow pump were designed by using different methods, in order to investigate the cavitation and hydraulic performance of the two models, the method of computational fluid dynamics (CFD) was adopted for internal flow simulation of the high specific speed mixed-flow pump. Based on the results of numerical simulation, the influences of impeller parameters and three-dimensional configuration on pressure distribution of the blades' suction surfaces were analyzed. The numerical simulation results shows a better pressure distribution and lower pressure drop around the leading edge of the improved model. The research results could provide references to the design and optimization of the anti-cavitation blade.

  2. Energy flow in high speed perforation and cutting

    International Nuclear Information System (INIS)

    van Thiel, M.

    1980-01-01

    It is demonstrated that effects of long rod penetrators on targets can be modeled by introducing a high pressure (energy) column on the penetration path in place of the projectile. This energy can be obtained from the kinetic energy of the penetrator; the equations of state of the materials used and a Bernoulli penetration condition. The model is supported by detailed hydro calculations

  3. Study on transient hydrodynamic performance and cavitation characteristic of high-speed mixed-flow pump

    International Nuclear Information System (INIS)

    Chen, T; Liu, Y L; Sun, Y B; Wang, L Q; Wu, D Z

    2013-01-01

    In order to analyse the hydrodynamic performance and cavitation characteristic of a high-speed mixed-flow pump during transient operations, experimental studies were carried out. The transient hydrodynamic performance and cavitation characteristics of the mixed-flow pump with guide vane during start-up operation processes were tested on the pump performance test-bed. Performance tests of the pump were carried out under various inlet pressures and speed-changing operations. The real-time instantaneous external characteristics such as rotational speed, hydraulic head, flow rate, suction pressure and discharge pressure of the pump were measured. Based on the experimental results, the effect of fluid acceleration on the hydrodynamic performances and cavitation characteristics of the mixed-flow pump were analysed and evaluated

  4. Positivity-preserving space-time CE/SE scheme for high speed flows

    KAUST Repository

    Shen, Hua

    2017-03-02

    We develop a space-time conservation element and solution element (CE/SE) scheme using a simple slope limiter to preserve the positivity of the density and pressure in computations of inviscid and viscous high-speed flows. In general, the limiter works with all existing CE/SE schemes. Here, we test the limiter on a central Courant number insensitive (CNI) CE/SE scheme implemented on hybrid unstructured meshes. Numerical examples show that the proposed limiter preserves the positivity of the density and pressure without disrupting the conservation law; it also improves robustness without losing accuracy in solving high-speed flows.

  5. Positivity-preserving space-time CE/SE scheme for high speed flows

    KAUST Repository

    Shen, Hua; Parsani, Matteo

    2017-01-01

    We develop a space-time conservation element and solution element (CE/SE) scheme using a simple slope limiter to preserve the positivity of the density and pressure in computations of inviscid and viscous high-speed flows. In general, the limiter works with all existing CE/SE schemes. Here, we test the limiter on a central Courant number insensitive (CNI) CE/SE scheme implemented on hybrid unstructured meshes. Numerical examples show that the proposed limiter preserves the positivity of the density and pressure without disrupting the conservation law; it also improves robustness without losing accuracy in solving high-speed flows.

  6. High-speed flow visualization in a pump-turbine under off-design operating conditions

    International Nuclear Information System (INIS)

    Hasmatuchi, V; Roth, S; Botero, F; Avellan, F; Farhat, M

    2010-01-01

    The flow hydrodynamics in a low specific speed radial pump-turbine reduced scale model is experimentally investigated under off-design operating conditions in generating mode. Wall pressure measurements, in the stator, synchronized with high-speed flow visualizations in the vaneless space between the impeller and the guide vanes using air bubbles injection are performed. When starting from the best efficiency point and increasing the runner speed, a significant increase of the pressure fluctuations is observed mainly in channels between wicket gates. The spectral analysis shows a rise of one stall cell, rotating with about 70% of the impeller frequency, at runaway, which further increases as the zero discharge condition is approached. Then a specific image processing technique is detailed and applied to create a synthetic instantaneous view of the flow pattern on the entire guide vanes circumference for an operating point in turbine-brake mode, where backflow and vortices accompany the stall passage.

  7. Application of PIV to the Measurement of High Speed Jet Flows

    Science.gov (United States)

    Lourenco, L.

    1999-01-01

    The Particle Image Velocimetry, PIV, has been implemented for the investigation of high-speed jet flows at the NASA Langley Research Center. In this approach the velocity (displacement) is found as the location of a peak in the correlation map of particle images acquired in quick succession. In the study, the technique for the correct seeding of the flow field were developed and implemented and the operational parameters influencing the accuracy of the measurement have been optimized.

  8. Characterization of Diamond Nanoparticles by High-Speed Micro-Thermal Field-Flow Fractionation

    Czech Academy of Sciences Publication Activity Database

    Janča, Josef

    2015-01-01

    Roč. 20, č. 8 (2015), s. 671-680 ISSN 1023-666X R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : diamond nanoparticles * high-speed microfluidic separation * micro-thermal field-flow fractionation, * article size distribution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.515, year: 2015

  9. Discussion of various flow calculation methods in high-speed centrifuges

    International Nuclear Information System (INIS)

    Louvet, P.; Cortet, C.

    1979-01-01

    The flow in high-speed centrifuges for the separation of uranium isotopes has been studied in the frame of linearized theory for long years. Three different methods have been derived for viscous compressible flow with small Ekman numbers and high Mach numbers: - numerical solution of flow equation by finite element method and Gaussian elimination (Centaure Code), - boundary layer theory using matched asymptotic expansions, - the so called eigenfunction method slightly modified. The mathematical assumptions, the easiness and the accuracy of the computations are compared. Numerical applications are performed successively for thermal countercurrent centrifuges with or without injections

  10. Energy transformation, transfer, and release dynamics in high speed turbulent flows

    Science.gov (United States)

    2017-03-01

    Secondly, a new high -order (4 th -order) convective flux formulation was developed that uses the tabulated information, yet produces a fully consistent...Klippenstein 2012 Comprehensive H2/O2 Kinetic Model for High - Pressure Combustion. Int. J. Chem. Kinetics 44:444-474. Cabot, W.H., A.W. Cook, P.L. Miller, D.E...AFRL-AFOSR-VA-TR-2017-0054 Energy Transformation, Transfer, and Release Dynamics in High -Speed Turbulent Flows Paul Dimotakis CALIFORNIA INSTITUTE

  11. Internal Flow of a High Specific-Speed Diagonal-Flow Fan (Rotor Outlet Flow Fields with Rotating Stall

    Directory of Open Access Journals (Sweden)

    Norimasa Shiomi

    2003-01-01

    Full Text Available We carried out investigations for the purpose of clarifying the rotor outlet flow fields with rotating stall cell in a diagonal-flow fan. The test fan was a high–specific-speed (ns=1620 type of diagonal-flow fan that had 6 rotor blades and 11 stator blades. It has been shown that the number of the stall cell is 1, and its propagating speed is approximately 80% of its rotor speed, although little has been known about the behavior of the stall cell because a flow field with a rotating stall cell is essentially unsteady. In order to capture the behavior of the stall cell at the rotor outlet flow fields, hot-wire surveys were performed using a single-slant hotwire probe. The data obtained by these surveys were processed by means of a double phase-locked averaging technique, which enabled us to capture the flow field with the rotating stall cell in the reference coordinate system fixed to the rotor. As a result, time-dependent ensemble averages of the three-dimensional velocity components at the rotor outlet flow fields were obtained. The behavior of the stall cell was shown for each velocity component, and the flow patterns on the meridional planes were illustrated.

  12. Nearly Interactive Parabolized Navier-Stokes Solver for High Speed Forebody and Inlet Flows

    Science.gov (United States)

    Benson, Thomas J.; Liou, May-Fun; Jones, William H.; Trefny, Charles J.

    2009-01-01

    A system of computer programs is being developed for the preliminary design of high speed inlets and forebodies. The system comprises four functions: geometry definition, flow grid generation, flow solver, and graphics post-processor. The system runs on a dedicated personal computer using the Windows operating system and is controlled by graphical user interfaces written in MATLAB (The Mathworks, Inc.). The flow solver uses the Parabolized Navier-Stokes equations to compute millions of mesh points in several minutes. Sample two-dimensional and three-dimensional calculations are demonstrated in the paper.

  13. Thermoconvective flow velocity in a high-speed magnetofluid seal after it has stopped

    OpenAIRE

    Krakov, M. S.; Nikiforov, I. V.

    2012-01-01

    Convective flow is investigated in the high-speed (linear velocity of the shaft seal is more than 1 m/s) magnetofluid shaft seal after it has been stopped. Magnetic fluid is preliminarily heated due to viscous friction in the moving seal. After the shaft has been stopped, nonuniform heated fluid remains under the action of a high-gradient magnetic field. Numerical analysis has revealed that in this situation, intense thermomagnetic convection is initiated. The velocity of magnetic fluid depen...

  14. High speed photography for investigating kiloampere discharges in supersonic air flows

    International Nuclear Information System (INIS)

    Jones, G.R.; Strachan, D.

    1975-01-01

    Examples of the use of conventional high speed photographic techniques are given for obtaining information about the behaviour of high current arc discharges in different gas flow fields. The photographic records yield information about the extent of both the luminous arc core and the surrounding heated volume of gas. A knowledge of these parameters leads to a better understanding of arc discharges which occur in gas blast circuit breakers. (author)

  15. Flow visualization of bubble behavior under two-phase natural circulation flow conditions using high speed digital camera

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Wanderley F.; Su, Jian, E-mail: wlemos@con.ufrj.br, E-mail: sujian@lasme.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Faccini, Jose L.H., E-mail: faccini@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. de Termo-Hidraulica Experimental

    2013-07-01

    The The present work aims at identifying flow patterns and measuring interfacial parameters in two-phase natural circulation by using visualization technique with high-speed digital camera. The experiments were conducted in the Natural Circulation Circuit (CCN), installed at Nuclear Engineering Institute/CNEN. The thermo-hydraulic circuit comprises heater, heat exchanger, expansion tank, the pressure relief valve and pipes to interconnect the components. A glass tube is installed at the midpoint of the riser connected to the heater outlet. The natural circulation circuit is complemented by acquisition system of values of temperatures, flow and graphic interface. The instrumentation has thermocouples, volumetric flow meter, rotameter and high-speed digital camera. The experimental study is performed through analysis of information from measurements of temperatures at strategic points along the hydraulic circuit, besides natural circulation flow rates. The comparisons between analytical and experimental values are validated by viewing, recording and processing of the images for the flows patterns. Variables involved in the process of identification of flow regimes, dimensionless parameters, the phase velocity of the flow, initial boiling point, the phenomenon of 'flashing' pre-slug flow type were obtained experimentally. (author)

  16. Flow visualization of bubble behavior under two-phase natural circulation flow conditions using high speed digital camera

    International Nuclear Information System (INIS)

    Lemos, Wanderley F.; Su, Jian; Faccini, Jose L.H.

    2013-01-01

    The The present work aims at identifying flow patterns and measuring interfacial parameters in two-phase natural circulation by using visualization technique with high-speed digital camera. The experiments were conducted in the Natural Circulation Circuit (CCN), installed at Nuclear Engineering Institute/CNEN. The thermo-hydraulic circuit comprises heater, heat exchanger, expansion tank, the pressure relief valve and pipes to interconnect the components. A glass tube is installed at the midpoint of the riser connected to the heater outlet. The natural circulation circuit is complemented by acquisition system of values of temperatures, flow and graphic interface. The instrumentation has thermocouples, volumetric flow meter, rotameter and high-speed digital camera. The experimental study is performed through analysis of information from measurements of temperatures at strategic points along the hydraulic circuit, besides natural circulation flow rates. The comparisons between analytical and experimental values are validated by viewing, recording and processing of the images for the flows patterns. Variables involved in the process of identification of flow regimes, dimensionless parameters, the phase velocity of the flow, initial boiling point, the phenomenon of 'flashing' pre-slug flow type were obtained experimentally. (author)

  17. Cadence® High High-Speed PCB Design Flow Workshop

    CERN Document Server

    2006-01-01

    Last release of Cadence High-Speed PCB Design methodology (PE142) based on Concept-HDL schematic editor, Constraint Manager, SPECCTRAQuest signal integrity analysis tool and ALLEGRO layout associated with SPECCTRA auto router tools, is now enough developed and stable to be taken into account for high-speed board designs at CERN. The implementation of this methodology, build around the new Constraint Manager program, is essential when you have to develop a board having a lot of high-speed design rules such as terminated lines, large bus structures, maximum length, timing, crosstalk etc.. that could not be under control by traditional method. On more conventional designs, formal aspect of the methodology could avoid misunderstanding between hardware and ALLEGRO layout designers, minimizing prototype iteration, development time and price. The capability to keep trace of the original digital designer intents in schematic or board layout, loading formal constraints in EDMS, could also be considered for LHC electro...

  18. Numerical analysis of high-speed liquid lithium free-surface flow

    International Nuclear Information System (INIS)

    Gordeev, Sergej; Heinzel, Volker; Stieglitz, Robert

    2012-01-01

    Highlights: ► The free surface behavior of a high speed lithium jet is investigated by means of a CFD LES analysis. ► The study is aiming to validate adequate LES technique. ► The Osaka University experiments with liquid lithium jet have been simulated. ► Four cases with jet flow velocities of 4, 9, 13 and 15 m/s are analyzed. ► Calculation results show a good qualitative and a quantitative agreement with the experimental data. - Abstract: The free-surface stability of the target of the International Fusion Material Irradiation Facility (IFMIF) is one of the crucial issues, since the spatio-temporal behavior of the free-surface determines the neutron flux to be generated. This article investigates the relation between the evolution of a wall boundary layer in a convergent nozzle and the free surface shape of a high speed lithium jet by means of a CFD LES analysis using the Osaka University experiments. The study is aiming to validate adequate LES technique to analyze the individual flow phenomena observed. Four cases with jet flow velocities of 4, 9, 13 and 15 m/s are analyzed. First analyses of calculation results show that the simulation exhibits a good qualitative and a quantitative agreement with the experimental data, which allows in the future a more realistic prediction of the IFMIF target behavior.

  19. Supercavitating flow around high-speed underwater projectile near free surface induced by air entrainment

    Directory of Open Access Journals (Sweden)

    Chang Xu

    2018-03-01

    Full Text Available Cavitating flow near free surface is a complicated issue and may provide new inspiration on high-speed surface cruising. This study observes stable supercavitating flow as a new phenomenon in a launch experiment of axisymmetric projectile when the upper side of the projectile coincides with the free surface. A numerical approach is established using large eddy-simulation and volume-of-fluid methods, and good agreements are achieved between numerical and experimental results. Supercavity formation mechanism is revealed by analyzing the experiment photographs and the iso-surface of 90% water volume fraction in numerical results. The entrainment of a large amount of air into the cavity can cause the pressure inside the cavity to similarly increase with the pressure outside the cavity, which makes the actual cavitation number close to zero and is similar to supercavitation. Cases with various headforms of the projectile and cavitation numbers on the cavitating flow, as well as the drag reduction effects are further examined. Results indicate that the present strategy near the free surface could possibly be a new effective approach for high-speed cruising after vigorous design optimization in the future.

  20. Thermoconvective flow velocity in a high-speed magnetofluid seal after it has stopped

    Science.gov (United States)

    Krakov, M. S.; Nikiforov, I. V.

    2012-09-01

    Convective flow is investigated in the high-speed (linear velocity of the shaft seal is more than 1 m/s) magnetofluid shaft seal after it has been stopped. Magnetic fluid is preliminarily heated due to viscous friction in the moving seal. After the shaft has been stopped, nonuniform heated fluid remains under the action of a high-gradient magnetic field. Numerical analysis has revealed that in this situation, intense thermomagnetic convection is initiated. The velocity of magnetic fluid depends on its viscosity. For the fluid with viscosity of 2 × 10-4 m2/s the maximum flow velocity within the volume of magnetic fluid with a characteristic size of 1 mm can attain a value of 10 m/s.

  1. High speed ultrasonic system to measure bubbles velocities in a horizontal two-phase flow

    International Nuclear Information System (INIS)

    Cunha Filho, Jurandyr S.; Jian Su; Farias, Marcos S.; Faccini, Jose L.H.; Lamy, Carlos A.

    2009-01-01

    In this work, a non invasive technique consisting of a high speed ultrasonic multitransducer pulse-echo system was developed to characterize gas-liquid two-phase flow parameters that are important in the study of the primary refrigeration circuit of nuclear reactors. The high speed ultrasonic system consists of two transducers (10 MHz/φ 6.35 mm), a generator/multiplexer board, and software that selects and has a data acquisition system of the ultrasonic signals. The resolutions of the system and the pulse time generated from each transducer are, respectively, 10 ns and 1.06 ms. The system initially was used in the local instantaneous measurement of gas-liquid interface in a circular horizontal pipe test section made of a 5 m long stainless steel pipe of 51.2 mm inner diameter, where the elongated bubbles velocity was measured (Taylor bubbles). The results show that the high speed ultrasonic pulse-echo system provides good results for the determination of elongated bubbles velocities. (author)

  2. Development of a Dual-PIV system for high-speed flow applications

    Science.gov (United States)

    Schreyer, Anne-Marie; Lasserre, Jean J.; Dupont, Pierre

    2015-10-01

    A new Dual-particle image velocimetry (Dual-PIV) system for application in supersonic flows was developed. The system was designed for shock wave/turbulent boundary layer interactions with separation. This type of flow places demanding requirements on the system, from the large range of characteristic frequencies O(100 Hz-100 kHz) to spatial and temporal resolutions necessary for the measurement of turbulent quantities (Dolling in AIAA J 39(8):1517-1531, 2001; Dupont et al. in J Fluid Mech 559:255-277, 2006; Smits and Dussauge in Turbulent shear layers in supersonic flow, 2nd edn. Springer, New York, 2006). While classic PIV systems using high-resolution CCD sensors allow high spatial resolution, these systems cannot provide the required temporal resolution. Existing high-speed PIV systems provide temporal and CMOS sensor resolutions, and even laser pulse energies, that are not adapted to our needs. The only obvious solution allowing sufficiently high spatial resolution, access to high frequencies, and a high laser pulse energy is a multi-frame system: a Dual-PIV system, consisting of two synchronized PIV systems observing the same field of view, will give access to temporal characteristics of the flow. The key technology of our system is frequency-based image separation: two lasers of different wavelengths illuminate the field of view. The cross-pollution with laser light from the respective other branches was quantified during system validation. The overall system noise was quantified, and the prevailing error of only 2 % reflects the good spatial and temporal alignment. The quality of the measurement system is demonstrated with some results on a subsonic jet flow including the spatio-temporal inter-correlation functions between the systems. First measurements in a turbulent flat-plate boundary layer at Mach 2 show the same satisfactory data quality and are also presented and discussed.

  3. ULTRA-SHARP nonoscillatory convection schemes for high-speed steady multidimensional flow

    Science.gov (United States)

    Leonard, B. P.; Mokhtari, Simin

    1990-01-01

    For convection-dominated flows, classical second-order methods are notoriously oscillatory and often unstable. For this reason, many computational fluid dynamicists have adopted various forms of (inherently stable) first-order upwinding over the past few decades. Although it is now well known that first-order convection schemes suffer from serious inaccuracies attributable to artificial viscosity or numerical diffusion under high convection conditions, these methods continue to enjoy widespread popularity for numerical heat transfer calculations, apparently due to a perceived lack of viable high accuracy alternatives. But alternatives are available. For example, nonoscillatory methods used in gasdynamics, including currently popular TVD schemes, can be easily adapted to multidimensional incompressible flow and convective transport. This, in itself, would be a major advance for numerical convective heat transfer, for example. But, as is shown, second-order TVD schemes form only a small, overly restrictive, subclass of a much more universal, and extremely simple, nonoscillatory flux-limiting strategy which can be applied to convection schemes of arbitrarily high order accuracy, while requiring only a simple tridiagonal ADI line-solver, as used in the majority of general purpose iterative codes for incompressible flow and numerical heat transfer. The new universal limiter and associated solution procedures form the so-called ULTRA-SHARP alternative for high resolution nonoscillatory multidimensional steady state high speed convective modelling.

  4. Development of Localized Arc Filament RF Plasma Actuators for High-Speed and High Reynolds Number Flow Control

    Science.gov (United States)

    2010-01-01

    high-speed flows is problematic due to their low forcing frequency (for mechanical actuators) and low forcing amplitude (for piezo actuators...very low fraction of DC power is coupled to the actuators (5-10%), with the rest of the power dissipated in massive ballast resistors acting as heat... resistors . The use of high-power resistors also significantly increases the weight and size of the plasma generator and makes scaling to a large number of

  5. A new phase coding method using a slice selection gradient for high speed flow velocity meaurements in NMR tomography

    International Nuclear Information System (INIS)

    Oh, C.H.; Cho, Z.H.; California Univ., Irvine

    1986-01-01

    A new phase coding method using a selection gradient for high speed NMR flow velocity measurements is introduced and discussed. To establish a phase-velocity relationship of flow under the slice selection gradient and spin-echo RF pulse, the Bloch equation was numerically solved under the assumption that only one directional flow exists, i.e. in the direction of slice selection. Details of the numerical solution of the Bloch equation and techniques related to the numerical computations are also given. Finally, using the numerical calculation, high speed flow velocity measurement was attempted and found to be in good agreement with other complementary controlled measurements. (author)

  6. Optical Flow-Field Techniques Used for Measurements in High-Speed Centrifugal Compressors

    Science.gov (United States)

    Skoch, Gary J.

    1999-01-01

    The overall performance of a centrifugal compressor depends on the performance of the impeller and diffuser as well as on the interactions occurring between these components. Accurate measurements of the flow fields in each component are needed to develop computational models that can be used in compressor design codes. These measurements must be made simultaneously over an area that covers both components so that researchers can understand the interactions occurring between the two components. Optical measurement techniques are being used at the NASA Lewis Research Center to measure the velocity fields present in both the impeller and diffuser of a 4:1 pressure ratio centrifugal compressor operating at several conditions ranging from design flow to surge. Laser Doppler Velocimetry (LDV) was used to measure the intrablade flows present in the impeller, and the results were compared with analyses obtained from two three-dimensional viscous codes. The development of a region of low throughflow velocity fluid within this high-speed impeller was examined and compared with a similar region first observed in a large low-speed centrifugal impeller at Lewis. Particle Image Velocimetry (PIV) is a relatively new technique that has been applied to measuring the diffuser flow fields. PIV can collect data rapidly in the diffuser while avoiding the light-reflection problems that are often encountered when LDV is used. The Particle Image Velocimeter employs a sheet of pulsed laser light that is introduced into the diffuser in a quasi-radial direction through an optical probe inserted near the diffuser discharge. The light sheet is positioned such that its centerline is parallel to the hub and shroud surfaces and such that it is parallel to the diffuser vane, thereby avoiding reflections from the solid surfaces. Seed particles small enough to follow the diffuser flow are introduced into the compressor at an upstream location. A high-speed charge-coupled discharge (CCD) camera is

  7. Model Reduction of Computational Aerothermodynamics for Multi-Discipline Analysis in High Speed Flows

    Science.gov (United States)

    Crowell, Andrew Rippetoe

    This dissertation describes model reduction techniques for the computation of aerodynamic heat flux and pressure loads for multi-disciplinary analysis of hypersonic vehicles. NASA and the Department of Defense have expressed renewed interest in the development of responsive, reusable hypersonic cruise vehicles capable of sustained high-speed flight and access to space. However, an extensive set of technical challenges have obstructed the development of such vehicles. These technical challenges are partially due to both the inability to accurately test scaled vehicles in wind tunnels and to the time intensive nature of high-fidelity computational modeling, particularly for the fluid using Computational Fluid Dynamics (CFD). The aim of this dissertation is to develop efficient and accurate models for the aerodynamic heat flux and pressure loads to replace the need for computationally expensive, high-fidelity CFD during coupled analysis. Furthermore, aerodynamic heating and pressure loads are systematically evaluated for a number of different operating conditions, including: simple two-dimensional flow over flat surfaces up to three-dimensional flows over deformed surfaces with shock-shock interaction and shock-boundary layer interaction. An additional focus of this dissertation is on the implementation and computation of results using the developed aerodynamic heating and pressure models in complex fluid-thermal-structural simulations. Model reduction is achieved using a two-pronged approach. One prong focuses on developing analytical corrections to isothermal, steady-state CFD flow solutions in order to capture flow effects associated with transient spatially-varying surface temperatures and surface pressures (e.g., surface deformation, surface vibration, shock impingements, etc.). The second prong is focused on minimizing the computational expense of computing the steady-state CFD solutions by developing an efficient surrogate CFD model. The developed two

  8. Development and application of a particle image velocimeter for high-speed flows

    Science.gov (United States)

    Molezzi, M. J.; Dutton, J. C.

    1992-01-01

    A particle image velocimetry (PIV) system has been developed for use in high-speed separated air flows. The image acquisition system uses two 550 mJ/pulse Nd:YAG lasers and is fully controlled by a host Macintosh computer. The interrogation system is also Macintosh-based and performs interrogations at approximately 2.3 sec/spot and 4.0 sec/spot when using the Young's fringe and autocorrelation methods, respectively. The system has been proven in preliminary experiments using known-displacement simulated PIV photographs and a simple axisymmetric jet flow. Further results have been obtained in a transonic wind tunnel operating at Mach 0.4 to 0.5 (135 m/s to 170 m/s). PIV experiments were done with an empty test section to provide uniform flow data for comparison with pressure and LDV data, then with a two-dimensional base model, revealing features of the von Karman vortex street wake and underlying small scale turbulence.

  9. Progress on a Taylor weak statement finite element algorithm for high-speed aerodynamic flows

    Science.gov (United States)

    Baker, A. J.; Freels, J. D.

    1989-01-01

    A new finite element numerical Computational Fluid Dynamics (CFD) algorithm has matured to the point of efficiently solving two-dimensional high speed real-gas compressible flow problems in generalized coordinates on modern vector computer systems. The algorithm employs a Taylor Weak Statement classical Galerkin formulation, a variably implicit Newton iteration, and a tensor matrix product factorization of the linear algebra Jacobian under a generalized coordinate transformation. Allowing for a general two-dimensional conservation law system, the algorithm has been exercised on the Euler and laminar forms of the Navier-Stokes equations. Real-gas fluid properties are admitted, and numerical results verify solution accuracy, efficiency, and stability over a range of test problem parameters.

  10. Effects of Injection Timing on Fluid Flow Characteristics of Partially Premixed Combustion Based on High-Speed Particle Image Velocimetry

    KAUST Repository

    Izadi Najafabadi, Mohammad; Tanov, Slavey; Wang, Hua; Somers, Bart; Johansson, Bengt; Dam, Nico

    2017-01-01

    behavior. The scope of the present study is to investigate the fluid flow characteristics of PPC at different injection timings. To this end, high-speed Particle Image Velocimetry (PIV) is implemented in a light-duty optical engine to measure fluid flow

  11. Tribological properties of high-speed steel treated by compression plasma flow

    International Nuclear Information System (INIS)

    Cherenda, K.K.; Uglov, V.V.; Anishchik, V.M.; Stalmashonak, A.K.; Astashinski, V.M.

    2004-01-01

    Full text: The investigation of tribological properties of two high-speed steels AISI M2 and AISI Tl treated by the nitrogen compression plasma flow was the main aim of this work. Two types of samples were investigated before and after quenching. The plasma flow was received in a magneto-plasma compressor. The impulse duration was ∼100 μs, the number of impulses varied in the range of 1-5, the nitrogen pressure in the chamber was 400-4000 Pa, the energy absorbed by the sample was 2-10 J/cm 2 per impulse. Tribological properties were examined by means of a tribometer TAYl under conditions of dry friction. The Vickers's microhardness was measured by a hard meter PMT3. X-ray diffraction analysis, Auger electron spectroscopy, scanning electron microscopy and energy dispersion microanalysis were used for samples characterization. The earlier conducted investigations showed that the compression plasma flow suited well for the improvement of tribological properties of iron and low-alloyed steels due to the formation of hardening nitrides in the near surface layer. It was found that in the case of high-speed steels only not quenched samples had increased hardness after treatment. The latter can be explained by the formation of hardening nitrides though the phase analysis did not clearly reveal their presence. The element composition confirmed the presence of nitrogen in the surface layer with the concentration up to 30 at. %. The treatment of quenched samples almost always resulted in the hardness decrease due to the dissolution or partial dissolution of alloying elements carbides: M 6 C, MC, M 23 C 6 . The rate of carbides dissolution increased with the growth of the energy absorbed by the sample. The treated samples showed a lower value of the friction coefficient than the untreated one. It could be explained by the formation of nitrogenous austenite which was found out by the phase analysis. At the same time the compression plasma flow strongly influenced surface

  12. Burst Speed of Wild Fishes under High-Velocity Flow Conditions Using Stamina Tunnel with Natural Guidance System in River

    Science.gov (United States)

    Izumi, Mattashi; Yamamoto, Yasuyuki; Yataya, Kenichi; Kamiyama, Kohhei

    Swimming experiments were conducted on wild fishes in a natural guidance system stamina tunnel (cylindrical pipe) installed in a fishway of a local river under high-velocity flow conditions (tunnel flow velocity : 211 to 279 cm·s-1). In this study, the swimming characteristics of fishes were observed. The results show that (1) the swimming speeds of Tribolodon hakonensis (Japanese dace), Phoxinus lagowshi steindachneri (Japanese fat-minnow), Plecoglossus altivelis (Ayu), and Zacco platypus (Pale chub) were in proportion to their body length under identical water flow velocity conditions; (2) the maximum burst speed of Japanese dace and Japanese fat-minnow (measuring 4 to 6 cm in length) was 262 to 319 cm·s-1 under high flow velocity conditions (225 to 230 cm·s-1), while the maximum burst speed of Ayu and Pale chub (measuring 5 cm to 12 cm in length) was 308 to 355 cm·s-1 under high flow velocity conditions (264 to 273 cm·s-1) ; (3) the 50cm-maximum swimming speed of swimming fishes was 1.07 times faster than the pipe-swimming speed; (4) the faster the flow velocity, the shorter the swimming distance became.

  13. Development of Modal Analysis for the Study of Global Modes in High Speed Boundary Layer Flows

    Science.gov (United States)

    Brock, Joseph Michael

    Boundary layer transition for compressible flows remains a challenging and unsolved problem. In the context of high-speed compressible flow, transitional and turbulent boundary-layers produce significantly higher surface heating caused by an increase in skin-friction. The higher heating associated with transitional and turbulent boundary layers drives thermal protection systems (TPS) and mission trajectory bounds. Proper understanding of the mechanisms that drive transition is crucial to the successful design and operation of the next generation spacecraft. Currently, prediction of boundary-layer transition is based on experimental efforts and computational stability analysis. Computational analysis, anchored by experimental correlations, offers an avenue to assess/predict stability at a reduced cost. Classical methods of Linearized Stability Theory (LST) and Parabolized Stability Equations (PSE) have proven to be very useful for simple geometries/base flows. Under certain conditions the assumptions that are inherent to classical methods become invalid and the use of LST/PSE is inaccurate. In these situations, a global approach must be considered. A TriGlobal stability analysis code, Global Mode Analysis in US3D (GMAUS3D), has been developed and implemented into the unstructured solver US3D. A discussion of the methodology and implementation will be presented. Two flow configurations are presented in an effort to validate/verify the approach. First, stability analysis for a subsonic cylinder wake is performed and results compared to literature. Second, a supersonic blunt cone is considered to directly compare LST/PSE analysis and results generated by GMAUS3D.

  14. Large-eddy simulation/Reynolds-averaged Navier-Stokes hybrid schemes for high speed flows

    Science.gov (United States)

    Xiao, Xudong

    Three LES/RANS hybrid schemes have been proposed for the prediction of high speed separated flows. Each method couples the k-zeta (Enstrophy) BANS model with an LES subgrid scale one-equation model by using a blending function that is coordinate system independent. Two of these functions are based on turbulence dissipation length scale and grid size, while the third one has no explicit dependence on the grid. To implement the LES/RANS hybrid schemes, a new rescaling-reintroducing method is used to generate time-dependent turbulent inflow conditions. The hybrid schemes have been tested on a Mach 2.88 flow over 25 degree compression-expansion ramp and a Mach 2.79 flow over 20 degree compression ramp. A special computation procedure has been designed to prevent the separation zone from expanding upstream to the recycle-plane. The code is parallelized using Message Passing Interface (MPI) and is optimized for running on IBM-SP3 parallel machine. The scheme was validated first for a flat plate. It was shown that the blending function has to be monotonic to prevent the RANS region from appearing in the LES region. In the 25 deg ramp case, the hybrid schemes provided better agreement with experiment in the recovery region. Grid refinement studies demonstrated the importance of using a grid independent blend function and further improvement with experiment in the recovery region. In the 20 deg ramp case, with a relatively finer grid, the hybrid scheme characterized by grid independent blending function well predicted the flow field in both the separation region and the recovery region. Therefore, with "appropriately" fine grid, current hybrid schemes are promising for the simulation of shock wave/boundary layer interaction problems.

  15. Flipping the analytical coin : closing the information flow loop in high speed (real time) analysis

    NARCIS (Netherlands)

    K.E. Shahroudi

    1997-01-01

    textabstractAnalysis modules tend to be set up as one way flow of information, i.e a clear distinction between cause and effect or input and output. However, as the speed of analysis approaches real time (or faster than movie rate), it becomes increasingly difficult for an external user to

  16. Ultra-high-speed digital in-line holography system applied to particle-laden supersonic underexpanded jet flows

    DEFF Research Database (Denmark)

    Ingvorsen, Kristian Mark; Buchmann, Nicolas A.; Soria, Julio

    2012-01-01

    -fluid interactions in these high-speed flows special high performance techniques are required. The present work is an investigation into the applicability of magnified digital in-line holography with ultra-high-speed recording for the study of three-dimensional supersonic particle-laden flows. An optical setup...... × 10mm calibration grid and 120 μm particles on a glass plate. In the case with the calibration grid it is found that accurate determination of the depthwise position is possible. However, when applying the same technique to the particle target, significant problems are encountered. © 2012...

  17. Large eddy simulation and direct numerical simulation of high speed turbulent reacting flows

    Science.gov (United States)

    Adumitroaie, V.; Frankel, S. H.; Madnia, C. K.; Givi, P.

    The objective of this research is to make use of Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) for the computational analyses of high speed reacting flows. Our efforts in the first phase of this research conducted within the past three years have been directed in several issues pertaining to intricate physics of turbulent reacting flows. In our previous 5 semi-annual reports submitted to NASA LaRC, as well as several technical papers in archival journals, the results of our investigations have been fully described. In this progress report which is different in format as compared to our previous documents, we focus only on the issue of LES. The reason for doing so is that LES is the primary issue of interest to our Technical Monitor and that our other findings were needed to support the activities conducted under this prime issue. The outcomes of our related investigations, nevertheless, are included in the appendices accompanying this report. The relevance of the materials in these appendices are, therefore, discussed only briefly within the body of the report. Here, results are presented of a priori and a posterior analyses for validity assessments of assumed Probability Density Function (PDF) methods as potential subgrid scale (SGS) closures for LES of turbulent reacting flows. Simple non-premixed reacting systems involving an isothermal reaction of the type A + B yields Products under both chemical equilibrium and non-equilibrium conditions are considered. A priori analyses are conducted of a homogeneous box flow, and a spatially developing planar mixing layer to investigate the performance of the Pearson Family of PDF's as SGS models. A posteriori analyses are conducted of the mixing layer using a hybrid one-equation Smagorinsky/PDF SGS closure. The Smagorinsky closure augmented by the solution of the subgrid turbulent kinetic energy (TKE) equation is employed to account for hydrodynamic fluctuations, and the PDF is employed for modeling the

  18. Automated high-speed video analysis of the bubble dynamics in subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Maurus, Reinhold; Ilchenko, Volodymyr; Sattelmayer, Thomas [Technische Univ. Muenchen, Lehrstuhl fuer Thermodynamik, Garching (Germany)

    2004-04-01

    Subcooled flow boiling is a commonly applied technique for achieving efficient heat transfer. In the study, an experimental investigation in the nucleate boiling regime was performed for water circulating in a closed loop at atmospheric pressure. The test-section consists of a rectangular channel with a one side heated copper strip and a very good optical access. For the optical observation of the bubble behaviour the high-speed cinematography is used. Automated image processing and analysis algorithms developed by the authors were applied for a wide range of mass flow rates and heat fluxes in order to extract characteristic length and time scales of the bubbly layer during the boiling process. Using this methodology, a huge number of bubble cycles could be analysed. The structure of the developed algorithms for the detection of the bubble diameter, the bubble lifetime, the lifetime after the detachment process and the waiting time between two bubble cycles is described. Subsequently, the results from using these automated procedures are presented. A remarkable novelty is the presentation of all results as distribution functions. This is of physical importance because the commonly applied spatial and temporal averaging leads to a loss of information and, moreover, to an unjustified deterministic view of the boiling process, which exhibits in reality a very wide spread of bubble sizes and characteristic times. The results show that the mass flux dominates the temporal bubble behaviour. An increase of the liquid mass flux reveals a strong decrease of the bubble life - and waiting time. In contrast, the variation of the heat flux has a much smaller impact. It is shown in addition that the investigation of the bubble history using automated algorithms delivers novel information with respect to the bubble lift-off probability. (Author)

  19. Automated high-speed video analysis of the bubble dynamics in subcooled flow boiling

    International Nuclear Information System (INIS)

    Maurus, Reinhold; Ilchenko, Volodymyr; Sattelmayer, Thomas

    2004-01-01

    Subcooled flow boiling is a commonly applied technique for achieving efficient heat transfer. In the study, an experimental investigation in the nucleate boiling regime was performed for water circulating in a closed loop at atmospheric pressure. The test-section consists of a rectangular channel with a one side heated copper strip and a very good optical access. For the optical observation of the bubble behaviour the high-speed cinematography is used. Automated image processing and analysis algorithms developed by the authors were applied for a wide range of mass flow rates and heat fluxes in order to extract characteristic length and time scales of the bubbly layer during the boiling process. Using this methodology, a huge number of bubble cycles could be analysed. The structure of the developed algorithms for the detection of the bubble diameter, the bubble lifetime, the lifetime after the detachment process and the waiting time between two bubble cycles is described. Subsequently, the results from using these automated procedures are presented. A remarkable novelty is the presentation of all results as distribution functions. This is of physical importance because the commonly applied spatial and temporal averaging leads to a loss of information and, moreover, to an unjustified deterministic view of the boiling process, which exhibits in reality a very wide spread of bubble sizes and characteristic times. The results show that the mass flux dominates the temporal bubble behaviour. An increase of the liquid mass flux reveals a strong decrease of the bubble life- and waiting time. In contrast, the variation of the heat flux has a much smaller impact. It is shown in addition that the investigation of the bubble history using automated algorithms delivers novel information with respect to the bubble lift-off probability

  20. Irrigant flow in the root canal: experimental validation of an unsteady Computational Fluid Dynamics model using high-speed imaging.

    Science.gov (United States)

    Boutsioukis, C; Verhaagen, B; Versluis, M; Kastrinakis, E; van der Sluis, L W M

    2010-05-01

    To compare the results of a Computational Fluid Dynamics (CFD) simulation of the irrigant flow within a prepared root canal, during final irrigation with a syringe and a needle, with experimental high-speed visualizations and theoretical calculations of an identical geometry and to evaluate the effect of off-centre positioning of the needle inside the root canal. A CFD model was created to simulate irrigant flow from a side-vented needle inside a prepared root canal. Calculations were carried out for four different positions of the needle inside a prepared root canal. An identical root canal model was made from poly-dimethyl-siloxane (PDMS). High-speed imaging of the flow seeded with particles and Particle Image Velocimetry (PIV) were combined to obtain the velocity field inside the root canal experimentally. Computational, theoretical and experimental results were compared to assess the validity of the computational model. Comparison between CFD computations and experiments revealed good agreement in the velocity magnitude and vortex location and size. Small lateral displacements of the needle inside the canal had a limited effect on the flow field. High-speed imaging experiments together with PIV of the flow inside a simulated root canal showed a good agreement with the CFD model, even though the flow was unsteady. Therefore, the CFD model is able to predict reliably the flow in similar domains.

  1. High-efficiency particulate air filter behavior at high-speed flows

    International Nuclear Information System (INIS)

    Tang, P.K.; Gregory, W.S.; Ricketts, C.I.; Smith, P.R.

    1984-04-01

    This paper presents a filter model based on the principle of fluid flow through porous media. The model includes both laminar and turbulent effects. The coefficients used in the model are determined empirically based on existing data. Deviation from the model is discussed

  2. Cadence® High-Speed PCB Layout Flow Workshop

    CERN Document Server

    2003-01-01

    Last release of Cadence High-Speed PCB Design methodology (PE142) based on Concept-HDL schematic editor, Constraint Manager, SPECCTRAQuest signal integrity analysis tool and ALLEGRO layout associated with SPECCTRA auto router tools, is now enough developed and stable to be taken into account for high-speed board designs at CERN. The implementation of this methodology, build around the new Constraint Manager program, is essential when you have to develop a board having a lot of high-speed design rules such as terminated lines, large bus structures, maximum length, timing, crosstalk etc.. that could not be under control by traditional method. On more conventional designs, formal aspect of the methodology could avoid misunderstanding between hardware and ALLEGRO layout designers, minimizing prototype iteration, development time and price. The capability to keep trace of the original digital designer intents in schematic or board layout, loading formal constraints in EDMS, could also be considered for LHC electro...

  3. Active control of massively separated high-speed/base flows with electric arc plasma actuators

    Science.gov (United States)

    DeBlauw, Bradley G.

    The current project was undertaken to evaluate the effects of electric arc plasma actuators on high-speed separated flows. Two underlying goals motivated these experiments. The first goal was to provide a flow control technique that will result in enhanced flight performance for supersonic vehicles by altering the near-wake characteristics. The second goal was to gain a broader and more sophisticated understanding of these complex, supersonic, massively-separated, compressible, and turbulent flow fields. The attainment of the proposed objectives was facilitated through energy deposition from multiple electric-arc plasma discharges near the base corner separation point. The control authority of electric arc plasma actuators on a supersonic axisymmetric base flow was evaluated for several actuator geometries, frequencies, forcing modes, duty cycles/on-times, and currents. Initially, an electric arc plasma actuator power supply and control system were constructed to generate the arcs. Experiments were performed to evaluate the operational characteristics, electromagnetic emission, and fluidic effect of the actuators in quiescent ambient air. The maximum velocity induced by the arc when formed in a 5 mm x 1.6 mm x 2 mm deep cavity was about 40 m/s. During breakdown, the electromagnetic emission exhibited a rise and fall in intensity over a period of about 340 ns. After breakdown, the emission stabilized to a near-constant distribution. It was also observed that the plasma formed into two different modes: "high-voltage" and "low-voltage". It is believed that the plasma may be switching between an arc discharge and a glow discharge for these different modes. The two types of plasma do not appear to cause substantial differences on the induced fluidic effects of the actuator. In general, the characterization study provided a greater fundamental understanding of the operation of the actuators, as well as data for computational model comparison. Preliminary investigations

  4. Phase-measuring laser holographic interferometer for use in high speed flows

    Science.gov (United States)

    Yanta, William J.; Spring, W. Charles, III; Gross, Kimberly Uhrich; McArthur, J. Craig

    Phase-measurement techniques have been applied to a dual-plate laser holographic interferometer (LHI). This interferometer has been used to determine the flowfield densities in a variety of two-dimensional and axisymmetric flows. In particular, LHI has been applied in three different experiments: flowfield measurements inside a two-dimensional scramjet inlet, flow over a blunt cone, and flow over an indented nose shape. Comparisons of experimentally determined densities with computational results indicate that, when phase-measurement techniques are used in conjunction with state-of-the-art image-processing instrumentation, holographic interferometry can be a diagnostic tool with high resolution, high accuracy, and rapid data retrieval.

  5. Development and Application of Plasma Actuators for Active Control of High-Speed and High Reynolds Number Flows

    Science.gov (United States)

    Sammy, Mo

    2010-01-01

    Active flow control is often used to manipulate flow instabilities to achieve a desired goal (e.g. prevent separation, enhance mixing, reduce noise, etc.). Instability frequencies normally scale with flow velocity scale and inversely with flow length scale (U/l). In a laboratory setting for such flow experiments, U is high, but l is low, resulting in high instability frequency. In addition, high momentum and high background noise & turbulence in the flow necessitate high amplitude actuation. Developing a high amplitude and high frequency actuator is a major challenge. Ironically, these requirements ease up in application (but other issues arise).

  6. Study on flow fields in high specific speed centrifugal compressor with unpinched vaneless diffuser

    International Nuclear Information System (INIS)

    Tamaki, Hideaki

    2013-01-01

    Performance of centrifugal compressors strongly depends on their internal flow fields. CFD has become indispensable tool for getting the information about flow fields in centrifugal compressors. CFD codes are usually validated by some representative data or compared with calculated results by other CFD codes, in order to ensure their accuracies. However, learning their accuracies for all types of centrifugal compressor's specifications requires continuous works that compare experimental data obtained in developmental processes of various types of centrifugal compressors with CFD results. A prediction of a performance and a flow field of a centrifugal compressor by CFD is relatively accurate when the impact of separation and secondary flow on that flow field is weak, i.e. near design condition. Centrifugal compressors are deemed to have a wide operating range alongside high efficiencies at design points. Hence the prediction accuracy of CFD at off design conditions, where the impacts of separation and secondary flow on the flow field are strong, is critical for the design of the centrifugal compressors. This study therefore investigated the prediction accuracy of CFD using a centrifugal compressor whose geometry was intentionally changed to have a distorted flow field over a whole operating range, i.e. from choke to surge.

  7. Study on flow fields in high specific speed centrifugal compressor with unpinched vaneless diffuser

    Energy Technology Data Exchange (ETDEWEB)

    Tamaki, Hideaki [IHI Corporation, Yokoham (Japan)

    2013-06-15

    Performance of centrifugal compressors strongly depends on their internal flow fields. CFD has become indispensable tool for getting the information about flow fields in centrifugal compressors. CFD codes are usually validated by some representative data or compared with calculated results by other CFD codes, in order to ensure their accuracies. However, learning their accuracies for all types of centrifugal compressor's specifications requires continuous works that compare experimental data obtained in developmental processes of various types of centrifugal compressors with CFD results. A prediction of a performance and a flow field of a centrifugal compressor by CFD is relatively accurate when the impact of separation and secondary flow on that flow field is weak, i.e. near design condition. Centrifugal compressors are deemed to have a wide operating range alongside high efficiencies at design points. Hence the prediction accuracy of CFD at off design conditions, where the impacts of separation and secondary flow on the flow field are strong, is critical for the design of the centrifugal compressors. This study therefore investigated the prediction accuracy of CFD using a centrifugal compressor whose geometry was intentionally changed to have a distorted flow field over a whole operating range, i.e. from choke to surge.

  8. Geometrically Flexible and Efficient Flow Analysis of High Speed Vehicles Via Domain Decomposition, Part 1: Unstructured-Grid Solver for High Speed Flows

    Science.gov (United States)

    White, Jeffery A.; Baurle, Robert A.; Passe, Bradley J.; Spiegel, Seth C.; Nishikawa, Hiroaki

    2017-01-01

    The ability to solve the equations governing the hypersonic turbulent flow of a real gas on unstructured grids using a spatially-elliptic, 2nd-order accurate, cell-centered, finite-volume method has been recently implemented in the VULCAN-CFD code. This paper describes the key numerical methods and techniques that were found to be required to robustly obtain accurate solutions to hypersonic flows on non-hex-dominant unstructured grids. The methods and techniques described include: an augmented stencil, weighted linear least squares, cell-average gradient method, a robust multidimensional cell-average gradient-limiter process that is consistent with the augmented stencil of the cell-average gradient method and a cell-face gradient method that contains a cell skewness sensitive damping term derived using hyperbolic diffusion based concepts. A data-parallel matrix-based symmetric Gauss-Seidel point-implicit scheme, used to solve the governing equations, is described and shown to be more robust and efficient than a matrix-free alternative. In addition, a y+ adaptive turbulent wall boundary condition methodology is presented. This boundary condition methodology is deigned to automatically switch between a solve-to-the-wall and a wall-matching-function boundary condition based on the local y+ of the 1st cell center off the wall. The aforementioned methods and techniques are then applied to a series of hypersonic and supersonic turbulent flat plate unit tests to examine the efficiency, robustness and convergence behavior of the implicit scheme and to determine the ability of the solve-to-the-wall and y+ adaptive turbulent wall boundary conditions to reproduce the turbulent law-of-the-wall. Finally, the thermally perfect, chemically frozen, Mach 7.8 turbulent flow of air through a scramjet flow-path is computed and compared with experimental data to demonstrate the robustness, accuracy and convergence behavior of the unstructured-grid solver for a realistic 3-D geometry on

  9. Two-dimensional computational modeling of high-speed transient flow in gun tunnel

    Science.gov (United States)

    Mohsen, A. M.; Yusoff, M. Z.; Hasini, H.; Al-Falahi, A.

    2018-03-01

    In this work, an axisymmetric numerical model was developed to investigate the transient flow inside a 7-meter-long free piston gun tunnel. The numerical solution of the gun tunnel was carried out using the commercial solver Fluent. The governing equations of mass, momentum, and energy were discretized using the finite volume method. The dynamic zone of the piston was modeled as a rigid body, and its motion was coupled with the hydrodynamic forces from the flow solution based on the six-degree-of-freedom solver. A comparison of the numerical data with the theoretical calculations and experimental measurements of a ground-based gun tunnel facility showed good agreement. The effects of parameters such as working gases and initial pressure ratio on the test conditions in the facility were examined. The pressure ratio ranged from 10 to 50, and gas combinations of air-air, helium-air, air-nitrogen, and air-CO2 were used. The results showed that steady nozzle reservoir conditions can be maintained for a longer duration when the initial conditions across the diaphragm are adjusted. It was also found that the gas combination of helium-air yielded the highest shock wave strength and speed, but a longer test time was achieved in the test section when using the CO2 test gas.

  10. Development of localized arc filament RF plasma actuators for high-speed and high Reynolds number flow control

    International Nuclear Information System (INIS)

    Kim, J.-H.; Nishihara, M.; Adamovich, I.V.; Samimy, M.; Gorbatov, S.V.; Pliavaka, F.V.

    2010-01-01

    Recently developed localized arc filament plasma actuators (LAFPAs) have shown tremendous control authority in high-speed and high Reynolds number flow for mixing enhancement and noise mitigation. Previously, these actuators were powered by a high-voltage pulsed DC plasma generator with low energy coupling efficiency of 5-10%. In the present work, a new custom-designed 8-channel pulsed radio frequency (RF) plasma generator has been developed to power up to 8 plasma actuators operated over a wide range of forcing frequencies (up to 50 kHz) and duty cycles (1-50%), and at high energy coupling efficiency (up to 80-85%). This reduces input electrical power requirements by approximately an order of magnitude, down to 12 W per actuator operating at 10% duty cycle. The new pulsed RF plasma generator is scalable to a system with a large number of channels. Performance of pulsed RF plasma actuators used for flow control was studied in a Mach 0.9 circular jet with a Reynolds number of about 623,000 and compared with that of pulsed DC actuators. Eight actuators were distributed uniformly on the perimeter of a 2.54-cm diameter circular nozzle extension. Both types of actuators coupled approximately the same amount of power to the flow, but with drastically different electrical inputs to the power supplies. Particle image velocimetry measurements showed that jet centerline Mach number decay produced by DC and RF actuators operating at the same forcing frequencies and duty cycles is very similar. At a forcing Strouhal number near 0.3, close to the jet column instability frequency, well-organized periodic structures, with similar patterns and dimensions, were generated in the jets forced by both DC and RF actuators. Far-field acoustic measurements demonstrated similar trends in the overall sound pressure level (OASPL) change produced by both types of actuators, resulting in OASPL reduction up to 1.2-1.5 dB in both cases. We conclude that pulsed RF actuators demonstrate flow

  11. Supercomputer implementation of finite element algorithms for high speed compressible flows. Progress report, period ending 30 June 1986

    International Nuclear Information System (INIS)

    Thornton, E.A.; Ramakrishnan, R.

    1986-06-01

    Prediction of compressible flow phenomena using the finite element method is of recent origin and considerable interest. Two shock capturing finite element formulations for high speed compressible flows are described. A Taylor-Galerkin formulation uses a Taylor series expansion in time coupled with a Galerkin weighted residual statement. The Taylor-Galerkin algorithms use explicit artificial dissipation, and the performance of three dissipation models are compared. A Petrov-Galerkin algorithm has as its basis the concepts of streamline upwinding. Vectorization strategies are developed to implement the finite element formulations on the NASA Langley VPS-32. The vectorization scheme results in finite element programs that use vectors of length of the order of the number of nodes or elements. The use of the vectorization procedure speeds up processing rates by over two orders of magnitude. The Taylor-Galerkin and Petrov-Galerkin algorithms are evaluated for 2D inviscid flows on criteria such as solution accuracy, shock resolution, computational speed and storage requirements. The convergence rates for both algorithms are enhanced by local time-stepping schemes. Extension of the vectorization procedure for predicting 2D viscous and 3D inviscid flows are demonstrated. Conclusions are drawn regarding the applicability of the finite element procedures for realistic problems that require hundreds of thousands of nodes

  12. Measurement of liquid film flow on nuclear rod bundle in micro-scale by using very high speed camera system

    Science.gov (United States)

    Pham, Son; Kawara, Zensaku; Yokomine, Takehiko; Kunugi, Tomoaki

    2012-11-01

    Playing important roles in the mass and heat transfer as well as the safety of boiling water reactor, the liquid film flow on nuclear fuel rods has been studied by different measurement techniques such as ultrasonic transmission, conductivity probe, etc. Obtained experimental data of this annular two-phase flow, however, are still not enough to construct the physical model for critical heat flux analysis especially at the micro-scale. Remain problems are mainly caused by complicated geometry of fuel rod bundles, high velocity and very unstable interface behavior of liquid and gas flow. To get over these difficulties, a new approach using a very high speed digital camera system has been introduced in this work. The test section simulating a 3×3 rectangular rod bundle was made of acrylic to allow a full optical observation of the camera. Image data were taken through Cassegrain optical system to maintain the spatiotemporal resolution up to 7 μm and 20 μs. The results included not only the real-time visual information of flow patterns, but also the quantitative data such as liquid film thickness, the droplets' size and speed distributions, and the tilt angle of wavy surfaces. These databases could contribute to the development of a new model for the annular two-phase flow. Partly supported by the Global Center of Excellence (G-COE) program (J-051) of MEXT, Japan.

  13. Longitudinal Plasmoid in High-Speed Vortex Gas Flow Created by Capacity HF Discharge

    Science.gov (United States)

    2010-10-28

    interferometer with high space resolution, PIV method, FTIR spectrometer, optical spectrometer, pressure sensors with high time resolution, IR pyrometer and...of strong LP-vortex interaction. Intensive acoustic waves are created by CHFD in swirl flow in this regime. 38. Study of control of a longitudinal...quartz tube, 4- HF ball electrode, 5- Tesla’s transformer, 6- microwave interferometer, 7- video camera, 8-optical pyrometer , 9-pressure sensor, 10

  14. Development of a Three-Dimensional Unstructured Euler Solver for High-Speed Flows

    Directory of Open Access Journals (Sweden)

    Tudorel Petronel AFILIPOAE

    2015-12-01

    Full Text Available This paper addresses the solution of the compressible Euler equations on hexahedral meshes for supersonic and hypersonic flows. Spatial discretization is accomplished by a cell-centered finite-volume formulation which employs two different upwind schemes for the computation of convective fluxes. Second-order solutions are attained through a linear state reconstruction technique that yields highly resolved flows in smooth regions while providing a sharp and clean resolution of shocks. The solution gradients required for the higher-order spatial discretization are estimated by a least-square method while Venkatakrishnan limiter is employed to preserve monotonicity and avoid oscillations in the presence of shocks. Furthermore, solutions are advanced in time by an explicit third-order Runge-Kutta scheme and convergence to steady state is accelerated using implicit residual smoothing. Flow around a circular arc in a channel and flow past a circular cylinder are studied and results are presented for various Mach numbers together with comparisons to theoretical and experimental data where possible.

  15. Experimental and Computational Study of Trapped Vortex Combustor Sector Rig with High-Speed Diffuser Flow

    Directory of Open Access Journals (Sweden)

    R. C. Hendricks

    2001-01-01

    Full Text Available The Trapped Vortex Combustor (TVC potentially offers numerous operational advantages over current production gas turbine engine combustors. These include lower weight, lower pollutant emissions, effective flame stabilization, high combustion efficiency, excellent high altitude relight capability, and operation in the lean burn or RQL modes of combustion. The present work describes the operational principles of the TVC, and extends diffuser velocities toward choked flow and provides system performance data. Performance data include EINOx results for various fuel-air ratios and combustor residence times, combustion efficiency as a function of combustor residence time, and combustor lean blow-out (LBO performance. Computational fluid dynamics (CFD simulations using liquid spray droplet evaporation and combustion modeling are performed and related to flow structures observed in photographs of the combustor. The CFD results are used to understand the aerodynamics and combustion features under different fueling conditions. Performance data acquired to date are favorable compared to conventional gas turbine combustors. Further testing over a wider range of fuel-air ratios, fuel flow splits, and pressure ratios is in progress to explore the TVC performance. In addition, alternate configurations for the upstream pressure feed, including bi-pass diffusion schemes, as well as variations on the fuel injection patterns, are currently in test and evaluation phases.

  16. High speed atom source

    International Nuclear Information System (INIS)

    Hoshino, Hitoshi.

    1990-01-01

    In a high speed atom source, since the speed is not identical between ions and electrons, no sufficient neutralizing effect for ionic rays due to the mixing of the ionic rays and the electron rays can be obtained failing to obtain high speed atomic rays at high density. In view of the above, a speed control means is disposed for equalizing the speed of ions forming ionic rays and the speed of electrons forming electron rays. Further, incident angle of the electron rays and/or ionic rays to a magnet or an electrode is made variable. As a result, the relative speed between the ions and the electrons to the processing direction is reduced to zero, in which the probability of association between the ions and the electrons due to the coulomb force is increased to improve the neutralizing efficiency to easily obtain fine and high density high speed electron rays. Further, by varying the incident angle, a track capable of obtaining an ideal mixing depending on the energy of the neutralized ionic rays is formed. Since the high speed electron rays has such high density, they can be irradiated easily to the minute region of the specimen. (N.H.)

  17. Ventilation of high-speed flows, an alternating methodology for the ventilator design

    International Nuclear Information System (INIS)

    Saldarriaga V, Juan G.; Navarrete, J.; Galeano B, Luis A.

    1996-01-01

    This article is about a research developed at Universidad de los Andes on the ventilation of high velocity flows as prevention against cavitations erosion. The research was a consequence of the results found in the physical model of the Guavio River Hydroelectric Project near Bogota and was based in a general model study of a spillway with ventilation system, which did not represent a particular prototype. In the Guavio study one conclusion was obtained:in every ventilation system there are three unknowns which are the air discharge injected to the water flow (design object variable), the sub pressure under the water jet and the jump length of that jet. In the research those three variables were studied using dimensional analysis and multivariable regressions in order to find a set of three equations that allow the design of this type of structures. The new equations are more general than those reported in technical literature

  18. Analysis of high-speed rotating flow inside gas centrifuge casing

    Science.gov (United States)

    Pradhan, Sahadev

    2017-11-01

    The generalized analytical model for the radial boundary layer inside the gas centrifuge casing in which the inner cylinder is rotating at a constant angular velocity Ωi while the outer one is stationary, is formulated for studying the secondary gas flow field due to wall thermal forcing, inflow/outflow of light gas along the boundaries, as well as due to the combination of the above two external forcing. The analytical model includes the sixth order differential equation for the radial boundary layer at the cylindrical curved surface in terms of master potential (χ) , which is derived from the equations of motion in an axisymmetric (r - z) plane. The linearization approximation is used, where the equations of motion are truncated at linear order in the velocity and pressure disturbances to the base flow, which is a solid-body rotation. Additional approximations in the analytical model include constant temperature in the base state (isothermal compressible Couette flow), high aspect ratio (length is large compared to the annular gap), high Reynolds number, but there is no limitation on the Mach number. The discrete eigenvalues and eigenfunctions of the linear operators (sixth-order in the radial direction for the generalized analytical equation) are obtained. The solutions for the secondary flow is determined in terms of these eigenvalues and eigenfunctions. These solutions are compared with direct simulation Monte Carlo (DSMC) simulations and found excellent agreement (with a difference of less than 15%) between the predictions of the analytical model and the DSMC simulations, provided the boundary conditions in the analytical model are accurately specified.

  19. Simultaneous two-phase flow measurement of spray mixing process by means of high-speed two-color PIV

    International Nuclear Information System (INIS)

    Zhang, Ming; Xu, Min; Hung, David L S

    2014-01-01

    In this article, a novel high-speed two-color PIV optical diagnostic technique has been developed and applied to simultaneously measure the velocity flow-fields of a multi-hole spark-ignition direct injection (SIDI) fuel injector spray and its ambient gas in a high-pressure constant volume chamber. To allow for the phase discrimination between the fuel droplets and ambient gas, a special tracer-filter system was designed. Fluorescent seeding particles with Sauter mean diameter (SMD) of 4.8 µm were used to trace the gas inside the chamber. With a single high-speed Nd:YLF laser sheet (527 nm) as the incident light source, the Mie-scattering signal marked the phase of the fuel spray, while the fluorescent signal generated from the seeding particles tracked the phase of ambient gas. A high-speed camera, with an image-doubler (mounted in front of the camera lens) that divided the camera pixels into two parts focusing on the same field of view, was used to collect the Mie-scattering signal and LIF (laser induced fluorescence) signal simultaneously with two carefully selected optical filters. To accommodate the large dynamic range of velocities in the two phases (1–2 orders of magnitude difference), two separation times (dt) were introduced. This technique was successfully applied to the liquid spray and ambient gas two-phase flow measurement. The measurement accuracy was compared with those from LDV (laser Doppler velocimetry) measurement and good agreement was obtained. Ambient gas motion surrounding the fuel spray was investigated and characterized into three zones. The momentum transfer process between the fuel spray and ambient gas in each zone was analyzed. The two-phase flow interaction under various superheated conditions was investigated. A strengthened momentum transfer from the liquid spray to the ambient was observed with increased superheat degree. (paper)

  20. High speed data acquisition

    International Nuclear Information System (INIS)

    Cooper, P.S.

    1997-07-01

    A general introduction to high speed data acquisition system techniques in modern particle physics experiments is given. Examples are drawn from the SELEX(E78 1) high statistics charmed baryon production and decay experiment now taking data at Fermilab

  1. Coupling Analysis of Low-Speed Multiphase Flow and High-Frequency Electromagnetic Field in a Complex Pipeline Structure

    Directory of Open Access Journals (Sweden)

    Xiaokai Huo

    2014-01-01

    Full Text Available Accurate estimation of water content in an oil-water mixture is a key technology in oil exploration and production. Based on the principles of the microwave transmission line (MTL, the logging probe is an important water content measuring apparatus. However, the effects of mixed fluid flow on the measurement of electromagnetic field parameters are rarely considered. This study presents the coupling model for low-speed multiphase flow and high-frequency electromagnetic field in a complex pipeline structure. We derived the S-parameter equations for the stratified oil/water flow model. The corresponding relationship between the S-parameters and water holdup is established. Evident coupling effects of the fluid flow and the electromagnetic field are confirmed by comparing the calculated S-parameters for both stratified and homogeneous flow patterns. In addition, a multiple-solution problem is analyzed for the inversion of dielectric constant from the S-parameters. The most sensitive phase angle range is determined to improve the detection of variation in the dielectric constant. Suggestions are proposed based on the influence of the oil/water layer on measurement sensitivity to optimize the geometric parameters of a device structure. The method proposed elucidates how accuracy and sensitivity can be improved in water holdup measurements under high water content conditions.

  2. "V-junction": a novel structure for high-speed generation of bespoke droplet flows.

    Science.gov (United States)

    Ding, Yun; Casadevall i Solvas, Xavier; deMello, Andrew

    2015-01-21

    We present the use of microfluidic "V-junctions" as a droplet generation strategy that incorporates enhanced performance characteristics when compared to more traditional "T-junction" formats. This includes the ability to generate target-sized droplets from the very first one, efficient switching between multiple input samples, the production of a wide range of droplet sizes (and size gradients) and the facile generation of droplets with residence time gradients. Additionally, the use of V-junction droplet generators enables the suspension and subsequent resumption of droplet flows at times defined by the user. The high degree of operational flexibility allows a wide range of droplet sizes, payloads, spacings and generation frequencies to be obtained, which in turn provides for an enhanced design space for droplet-based experimentation. We show that the V-junction retains the simplicity of operation associated with T-junction formats, whilst offering functionalities normally associated with droplet-on-demand technologies.

  3. Aerothermal and aeroelastic response prediction of aerospace structures in high-speed flows using direct numerical simulation

    Science.gov (United States)

    Ostoich, Christopher Mark

    Future high-speed air vehicles will be lightweight, flexible, and reusable. Ve- hicles fitting this description are subject to severe thermal and fluid dynamic loading from multiple sources such as aerothermal heating, propulsion sys- tem exhaust, and high dynamic pressures. The combination of low-margin design requirements and extreme environmental conditions emphasizes the occurrence of fluid-thermal-structural coupling. Numerous attempts to field such vehicles have been unsuccessful over the past half-century due par- tially to the inability of traditional design and analysis practices to predict the structural response in this flight regime. In this thesis, a high-fidelity computational approach is used to examine the fluid-structural response of aerospace structures in high-speed flows. The method is applied to two cases: one involving a fluid-thermal interaction problem in a hypersonic flow and the other a fluid-structure interaction study involving a turbulent boundary layer and a compliant panel. The coupled fluid-thermal investigation features a nominally rigid alu- minum spherical dome fixed to a ceramic panel holder placed in a Mach 6.59 laminar boundary layer. The problem was originally studied by Glass and Hunt in a 1988 wind tunnel experiment in the NASA Langley 8-Foot High Temperature Tunnel and is motivated by thermally bowed body panels designed for the National Aerospace Plane. In this work, the compressible Navier-Stokes equations for a thermally perfect gas and the transient heat equation in the structure are solved simultaneously using two high-fidelity solvers coupled at the solid-fluid interface. Predicted surface heat fluxes are within 10% of the measured values in the dome interior with greater differ- ences found near the dome edges where uncertainties concerning the exper- imental model's construction likely influence the thermal dynamics. On the flat panel holder, the local surface heat fluxes approach those on the wind- ward dome face

  4. Experimental and analytical studies on high-speed plane jet along concave wall simulating IFMIF Li target flow

    International Nuclear Information System (INIS)

    Nakamura, H.; Ida, M.; Kato, Y.; Maekawa, H.; Katsuta, H.; Itoh, K.; Kukita, Y.

    1998-01-01

    As part of the conceptual design activity (CDA) of the international fusion materials irradiation facility (IFMIF), the characteristics of the high-speed liquid lithium (Li) plane jet target flow have been studied by water experiments and numerical analyses for both heating and non-heating conditions. The simulated prototypal-size water flows were stable over the entire length of ∝130 mm at the average velocity up to 17 m/s. The jet flow had a specific radial velocity profile, close to that of free-vortex flow, because of a static pressure distribution in the jet thickness due to centrifugal force. Detailed velocity measurement revealed that this flow condition is penetrating into the upstream reducer nozzle up to a distance ∼ the jet thickness. The numerical analyses using a two-dimensional Cartesian-coordinate model were successful to predict the velocity profile transient around the nozzle exit, though underestimated the development of the velocity profile and the jet thickness. (orig.)

  5. Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

    Energy Technology Data Exchange (ETDEWEB)

    Mitroglou, N.; Lorenzi, M.; Gavaises, M. [City University London, School of Mathematics Computer Science and Engineering, London (United Kingdom); Santini, M. [University of Bergamo, Department of Engineering, Bergamo (Italy)

    2016-11-15

    The flow inside a purpose built enlarged single-orifice nozzle replica is quantified using time-averaged X-ray micro-computed tomography (micro-CT) and high-speed shadowgraphy. Results have been obtained at Reynolds and cavitation numbers similar to those of real-size injectors. Good agreement for the cavitation extent inside the orifice is found between the micro-CT and the corresponding temporal mean 2D cavitation image, as captured by the high-speed camera. However, the internal 3D structure of the developing cavitation cloud reveals a hollow vapour cloud ring formed at the hole entrance and extending only at the lower part of the hole due to the asymmetric flow entry. Moreover, the cavitation volume fraction exhibits a significant gradient along the orifice volume. The cavitation number and the needle valve lift seem to be the most influential operating parameters, while the Reynolds number seems to have only small effect for the range of values tested. Overall, the study demonstrates that use of micro-CT can be a reliable tool for cavitation in nozzle orifices operating under nominal steady-state conditions. (orig.)

  6. Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

    Science.gov (United States)

    Mitroglou, N.; Lorenzi, M.; Santini, M.; Gavaises, M.

    2016-11-01

    The flow inside a purpose built enlarged single-orifice nozzle replica is quantified using time-averaged X-ray micro-computed tomography (micro-CT) and high-speed shadowgraphy. Results have been obtained at Reynolds and cavitation numbers similar to those of real-size injectors. Good agreement for the cavitation extent inside the orifice is found between the micro-CT and the corresponding temporal mean 2D cavitation image, as captured by the high-speed camera. However, the internal 3D structure of the developing cavitation cloud reveals a hollow vapour cloud ring formed at the hole entrance and extending only at the lower part of the hole due to the asymmetric flow entry. Moreover, the cavitation volume fraction exhibits a significant gradient along the orifice volume. The cavitation number and the needle valve lift seem to be the most influential operating parameters, while the Reynolds number seems to have only small effect for the range of values tested. Overall, the study demonstrates that use of micro-CT can be a reliable tool for cavitation in nozzle orifices operating under nominal steady-state conditions.

  7. Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

    International Nuclear Information System (INIS)

    Mitroglou, N.; Lorenzi, M.; Gavaises, M.; Santini, M.

    2016-01-01

    The flow inside a purpose built enlarged single-orifice nozzle replica is quantified using time-averaged X-ray micro-computed tomography (micro-CT) and high-speed shadowgraphy. Results have been obtained at Reynolds and cavitation numbers similar to those of real-size injectors. Good agreement for the cavitation extent inside the orifice is found between the micro-CT and the corresponding temporal mean 2D cavitation image, as captured by the high-speed camera. However, the internal 3D structure of the developing cavitation cloud reveals a hollow vapour cloud ring formed at the hole entrance and extending only at the lower part of the hole due to the asymmetric flow entry. Moreover, the cavitation volume fraction exhibits a significant gradient along the orifice volume. The cavitation number and the needle valve lift seem to be the most influential operating parameters, while the Reynolds number seems to have only small effect for the range of values tested. Overall, the study demonstrates that use of micro-CT can be a reliable tool for cavitation in nozzle orifices operating under nominal steady-state conditions. (orig.)

  8. High-Speed Photography

    International Nuclear Information System (INIS)

    Paisley, D.L.; Schelev, M.Y.

    1998-01-01

    The applications of high-speed photography to a diverse set of subjects including inertial confinement fusion, laser surgical procedures, communications, automotive airbags, lightning etc. are briefly discussed. (AIP) copyright 1998 Society of Photo-Optical Instrumentation Engineers

  9. High speed heterostructure devices

    CERN Document Server

    Beer, Albert C; Willardson, R K; Kiehl, Richard A; Sollner, T C L Gerhard

    1994-01-01

    Volume 41 includes an in-depth review of the most important, high-speed switches made with heterojunction technology. This volume is aimed at the graduate student or working researcher who needs a broad overview andan introduction to current literature. Key Features * The first complete review of InP-based HFETs and complementary HFETs, which promise very low power and high speed * Offers a complete, three-chapter review of resonant tunneling * Provides an emphasis on circuits as well as devices.

  10. High-temperature epoxidation of soybean oil in flow : speeding up elemental reactions wanted and unwanted

    NARCIS (Netherlands)

    Cortese, B.; Croon, de M.H.J.M.; Hessel, V.

    2012-01-01

    The soybean oil epoxidation reaction is investigated theoretically through kinetic modeling of temperature effects enabled through flow processing under superheated conditions. Different from previous studies on such processing, here a complex reaction network superimposed by multiphase transport is

  11. Stability Analysis of High-Speed Boundary-Layer Flow with Gas Injection

    Science.gov (United States)

    2014-06-01

    laminar-turbulent transition on slender bodies in a hypersonic flow at small angles of attack is caused by amplification of acoustic waves trapped in...x decreases and slowly approaches the no-blow distribution. These CFD data demonstrate that the injection strongly affects the near-wall flow...conclusion. Figure 10 shows that the spatial growth rates ( )  are maximal for mode 0 corresponding to the Mack second mode – typical for hypersonic

  12. High-Speed Synchrotron X-ray Imaging Studies of the Ultrasound Shockwave and Enhanced Flow during Metal Solidification Processes

    Science.gov (United States)

    Tan, Dongyue; Lee, Tung Lik; Khong, Jia Chuan; Connolley, Thomas; Fezzaa, Kamel; Mi, Jiawei

    2015-07-01

    The highly dynamic behavior of ultrasonic bubble implosion in liquid metal, the multiphase liquid metal flow containing bubbles and particles, and the interaction between ultrasonic waves and semisolid phases during solidification of metal were studied in situ using the complementary ultrafast and high-speed synchrotron X-ray imaging facilities housed, respectively, at the Advanced Photon Source, Argonne National Laboratory, US, and Diamond Light Source, UK. Real-time ultrafast X-ray imaging of 135,780 frames per second revealed that ultrasonic bubble implosion in a liquid Bi-8 wt pctZn alloy can occur in a single wave period (30 kHz), and the effective region affected by the shockwave at implosion was 3.5 times the original bubble diameter. Furthermore, ultrasound bubbles in liquid metal move faster than the primary particles, and the velocity of bubbles is 70 ~ 100 pct higher than that of the primary particles present in the same locations close to the sonotrode. Ultrasound waves can very effectively create a strong swirling flow in a semisolid melt in less than one second. The energetic flow can detach solid particles from the liquid-solid interface and redistribute them back into the bulk liquid very effectively.

  13. Numerical analysis of high-speed Lithium jet flow under vacuum conditions

    International Nuclear Information System (INIS)

    Gordeev, Sergej; Groeschel, Friedrich; Stieglitz, Robert

    2016-01-01

    The EVEDA Li test loop (ELTL) [1] is aimed at validating the hydraulic stability of the Lithium (Li) target at a velocity up to 20 m/s at vacuum (≈10 −3 Pa). The ELTL has been designed to demonstrate the feasibility of the major components providing a neutron production liquid Li target for IFMIF. The rectangular shaped Li jet (cross-section 25 mm × 100 mm) necessitates for heat removal flow velocities of 15–20 m/s along a concave shaped back wall (curvature radius 250 mm) towards the outlet pipe, where the Li jet is subjected to vacuum before it finally enters the collecting quench tank. During the validation experiments within the ELTL acoustic waves within the target outlet pipe have been recorded, indicating potential cavitation processes in the jet impinging region, which may cause premature failures. In order to identify potential cavitation phenomena in correlation with the free jet flow in the outlet pipe a numerical study has been performed. The comparison measured and simulated acoustic emissions exhibits that experimentally deduced cavitation area coincides with the location of the jet wall impingement. The simulations further reveal that a part of the fluid after striking the wall even flows opposite to the gravity vector. This reversed flow is inherently unstable and characterized by waves at first growing and then bursting into droplets. The intense generation of small droplets increases significantly the Li free surface area and lead to a production of Li vapour, which is captured by the jet flow and reintroduced in the main flow. As the static pressure is recovered downstream due to jet impact, the vapour bubbles collapse and hence cavitation likely occurs.

  14. Numerical analysis of high-speed Lithium jet flow under vacuum conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gordeev, Sergej, E-mail: sergej.gordeev@kit.edu; Groeschel, Friedrich; Stieglitz, Robert

    2016-11-01

    The EVEDA Li test loop (ELTL) [1] is aimed at validating the hydraulic stability of the Lithium (Li) target at a velocity up to 20 m/s at vacuum (≈10{sup −3} Pa). The ELTL has been designed to demonstrate the feasibility of the major components providing a neutron production liquid Li target for IFMIF. The rectangular shaped Li jet (cross-section 25 mm × 100 mm) necessitates for heat removal flow velocities of 15–20 m/s along a concave shaped back wall (curvature radius 250 mm) towards the outlet pipe, where the Li jet is subjected to vacuum before it finally enters the collecting quench tank. During the validation experiments within the ELTL acoustic waves within the target outlet pipe have been recorded, indicating potential cavitation processes in the jet impinging region, which may cause premature failures. In order to identify potential cavitation phenomena in correlation with the free jet flow in the outlet pipe a numerical study has been performed. The comparison measured and simulated acoustic emissions exhibits that experimentally deduced cavitation area coincides with the location of the jet wall impingement. The simulations further reveal that a part of the fluid after striking the wall even flows opposite to the gravity vector. This reversed flow is inherently unstable and characterized by waves at first growing and then bursting into droplets. The intense generation of small droplets increases significantly the Li free surface area and lead to a production of Li vapour, which is captured by the jet flow and reintroduced in the main flow. As the static pressure is recovered downstream due to jet impact, the vapour bubbles collapse and hence cavitation likely occurs.

  15. The flow over a 'high' aspect ratio gothic wing at supersonic speeds

    Science.gov (United States)

    Narayan, K. Y.

    1975-01-01

    Results are presented of an experimental investigation on a nonconical wing which supports an attached shock wave over a region of the leading edge near the vertex and a detached shock elsewhere. The shock detachment point is determined from planform schlieren photographs of the flow field and discrepancies are shown to exist between this and the one calculated by applying the oblique shock equations normal to the leading edge. On a physical basis, it is argued that the shock detachment has to obey the two-dimensional law normal to the leading edges. From this, and from other measurements on conical wings, it is thought that the planform schlieren technique may not be particularly satisfactory for detecting shock detachment. Surface pressure distributions are presented and are explained in terms of the flow over related delta wings which are identified as a vertex delta wing and a local delta wing.

  16. Relaxation with high-speed plasma flows and singularity analysis in MHD equilibrium

    International Nuclear Information System (INIS)

    Shiraishi, Junya; Ohsaki, Shuichi; Yoshida, Zensho

    2004-01-01

    Relaxation model that leads to plasma confinement with rigid-rotation is presented. This model applies to Jupiter's magnetosphere. It is shown that the invariance of canonical angular momentum of electron fluid, which is realized by axisymmetry through self-organization process, yields plasma confinement. including poloidal flows in equilibrium equation makes the problem rather complicated. Singularity due to the poloidal flow is focused on. It is shown that the singular equation for equilibrium has the same structure as the equation for linear Alfven wave. Since the singular solution for equilibrium equation is physically inadequate, the singularity may be removed by another physical effect. The Hall-effect is taken into account as a singular perturbation that removes the singularity of equilibrium equation for ideal magnetohydrodynamics. (author)

  17. The characterisation of diesel nozzle flow using high speed imaging of elastic light scattering

    OpenAIRE

    Lockett, R. D.; Liverani, L.; Thaker, D.; Jeshani, M.; Tait, N. P.

    2013-01-01

    Two identical, conventional six-hole, valve-covered orifice (VCO) diesel injectors have been modified in order to provide optical access to the region below the needle, and the nozzle-flow passages. This has been achieved through the removal of the metal tips, and their replacement with transparent acrylic tips of identical geometry. \\ud \\ud These two identical injectors were employed in order to offer comparability between the measurements. One of them had a dark, anodised inner surface at t...

  18. Local Limit Phenomena, Flow Compression, and Fuel Cracking Effects in High-Speed Turbulent Flames

    Science.gov (United States)

    2015-06-01

    e.g. local extinction and re- ignition , interactions between flow compression and fast-reaction induced dilatation (reaction compression ), and to...time as a function of initial temperature in constant-pressure auto - ignition , and (b) the S-curves of perfectly stirred reactors (PSRs), for n...mechanism. The reduction covered auto - ignition and perfectly stirred reactors for equivalence ratio range of 0.5~1.5, initial temperature higher than

  19. Stability management of high speed axial flow compressor stage through axial extensions of bend skewed casing treatment

    Directory of Open Access Journals (Sweden)

    DilipkumarBhanudasji Alone

    2016-09-01

    Full Text Available This paper presents the experimental results to understand the performance of moderately loaded high speed single stage transonic axial flow compressor subjected to various configurations of axial extensions of bend skewed casing treatment with moderate porosity. The bend skewed casing treatment of 33% porosity was coupled with rectangular plenum chamber of depth equal to the slots depth. The five axial extensions of 20%, 40%, 60%, 80% and 100% were used for the experimental evaluations of compressor performance. The main objective was to identify the optimum extension of the casing treatment with reference to rotor leading edge which results in maximum stall margin improvements with minimum loss in the stage efficiency. At each axial extension the compressor performance is distinctive. The improvement in the stall margin was very significant at some axial extensions with 4%–5% penalty in the stage efficiency. The compressors stage shows recovery in terms of efficiency at lower axial extensions of 20% and 40% with increase in the peak stage efficiency. Measurements of flow parameters showed the typical behaviors at near stall flow conditions. Hot wire sensor was placed at the rotor upstream in the tip region to capture the oscillations in the inlet axial and tangential velocities at stall conditions. In the absence of casing treatment the compressor exhibit abrupt stall with very high oscillations in the inlet axial and tangential velocity of the flow. The extents of oscillations reduce with bend skewed casing treatment. Few measurements were also performed in the plenum chamber and salient results are presented in this paper.

  20. A new particle-like method for high-speed flows with chemical non-equilibrium

    Directory of Open Access Journals (Sweden)

    Fábio Rodrigues Guzzo

    2010-04-01

    Full Text Available The present work is concerned with the numerical simulation of hypersonic blunt body flows with chemical non-equilibrium. New theoretical and numerical formulations for coupling the chemical reaction to the fluid dynamics are presented and validated. The fluid dynamics is defined for a stationary unstructured mesh and the chemical reaction process is defined for “finite quantities” moving through the stationary mesh. The fluid dynamics is modeled by the Euler equations and the chemical reaction rates by the Arrhenius law. Ideal gases are considered. The thermodynamical data are based on JANNAF tables and Burcat’s database. The algorithm proposed by Liou, known as AUSM+, is implemented in a cell-centered based finite volume method and in an unstructured mesh context. Multidimensional limited MUSCL interpolation method is used to perform property reconstructions and to achieve second-order accuracy in space. The minmod limiter is used. The second order accuracy, five stage, Runge-Kutta time-stepping scheme is employed to perform the time march for the fluid dynamics. The numerical code VODE, which is part of the CHEMKIN-II package, is adopted to perform the time integration for the chemical reaction equations. The freestream reacting fluid is composed of H2 and air at the stoichiometric ratio. The emphasis of the present paper is on the description of the new methodology for handling the coupling of chemical and fluid mechanic processes, and its validation by comparison with the standard time-splitting procedure. The configurations considered are the hypersonic flow over a wedge, in which the oblique detonation wave is induced by an oblique shock wave, and the hypersonic flow over a blunt body. Differences between the solutions obtained with each formulation are presented and discussed, including the effects of grid refinement in each case. The primary objective of such comparisons is the validation of the proposed methodology. Moreover, for

  1. Numerical Simulation of a Nanosecond-Pulse Discharge for High-Speed Flow Control

    Science.gov (United States)

    Poggie, Jonathan; Adamovich, Igor

    2012-10-01

    Numerical calculations were carried out to examine the physics of the operation of a nanosecond-pulse, single dielectric barrier discharge in a configuration with planar symmetry. This simplified configuration was chosen as a vehicle to develop a physics based nanosecond discharge model, including realistic air plasma chemistry and compressible bulk gas flow. First, a reduced plasma kinetic model was developed by carrying out a sensitivity analysis of zero-dimensional plasma computations with an extended chemical kinetic model. Transient, one- dimensional discharge computations were then carried out using the reduced kinetic model, incorporating a drift-diffusion formulation for each species, a self-consistent computation of the electric potential using the Poisson equation, and a mass-averaged gas dynamic formulation for the bulk gas motion. Discharge parameters (temperature, pressure, and input waveform) were selected to be representative of recent experiments on bow shock control with a nanosecond discharge in a Mach 5 cylinder flow. The computational results qualitatively reproduce many of the features observed in the experiments, including the rapid thermalization of the input electrical energy and the consequent formation of a weak shock wave. At breakdown, input electrical energy is rapidly transformed (over roughly 1 ns) into ionization products, dissociation products, and electronically excited particles, with subsequent thermalization over a relatively longer time-scale (roughly 10 μs).

  2. Femtosecond two-photon laser-induced fluorescence of krypton for high-speed flow imaging.

    Science.gov (United States)

    Wang, Yejun; Capps, Cade; Kulatilaka, Waruna D

    2017-02-15

    Ultrashort-pulse (femtosecond-duration) two-photon laser-induced fluorescence (fs-TPLIF) of an inert gas tracer krypton (Kr) is investigated. A detailed spectroscopic study of fluorescence channels followed by the 5p'←←4p excitation of Kr at 204.1 nm is reported. The experimental line positions in the 750-840 nm emission region agree well with the NIST Atomic Spectra Database. The present work provides an accurate listing of relative line strengths in this spectral region. In the range of laser pulse energies investigated, a quadratic dependence was observed between the Kr-TPLIF signal and the laser pulse energy. The single-laser-shot 2D TPLIF images recorded in an unsteady jet demonstrate the potential of using fs excitation at 204.1 nm for mixing and flow diagnostic studies using Kr as an inert gas tracer.

  3. Effects of Injection Timing on Fluid Flow Characteristics of Partially Premixed Combustion Based on High-Speed Particle Image Velocimetry

    KAUST Repository

    Izadi Najafabadi, Mohammad

    2017-03-28

    Partially Premixed Combustion (PPC) is a promising combustion concept ,based on judicious tuning of the charge stratification, to meet the increasing demands of emission legislation and to improve fuel efficiency. Longer ignition delays of PPC in comparison with conventional diesel combustion provide better fuel/air mixture which decreases soot and NO emissions. Moreover, a proper injection timing and strategy for PPC can improve the combustion stability as a result of a higher level of fuel stratification in comparison with the Homogeneous Charge Compression Ignition (HCCI) concept. Injection timing is the major parameter with which to affect the level of fuel and combustion stratification and to control the combustion phasing and the heat release behavior. The scope of the present study is to investigate the fluid flow characteristics of PPC at different injection timings. To this end, high-speed Particle Image Velocimetry (PIV) is implemented in a light-duty optical engine to measure fluid flow characteristics, including the flow fields, mean velocity and cycle-resolved turbulence, inside the piston bowl as well as the squish region with a temporal resolution of 1 crank angle degree at 800 rpm. Two injectors, having 5 and 7 holes, were compared to see their effects on fluid flow and heat release behavior for different injection timings. Reactive and non-reactive measurements were performed to distinguish injection-driven and combustion-driven turbulence. Formation of vortices and higher turbulence levels enhance the air/fuel interaction, changing the level of fuel stratification and combustion duration. Results demonstrate clearly how turbulence level correlates with heat release behavior, and provide a quantitative dataset for validation of numerical simulations.

  4. High-Speed Diagnostic Measurements of Inlet and Exhaust Flows, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The development of rocket-based and turbine-based combined cycle engines are a high priority for transportation into space. In order to test components and systems,...

  5. Accurate prediction of complex free surface flow around a high speed craft using a single-phase level set method

    Science.gov (United States)

    Broglia, Riccardo; Durante, Danilo

    2017-11-01

    This paper focuses on the analysis of a challenging free surface flow problem involving a surface vessel moving at high speeds, or planing. The investigation is performed using a general purpose high Reynolds free surface solver developed at CNR-INSEAN. The methodology is based on a second order finite volume discretization of the unsteady Reynolds-averaged Navier-Stokes equations (Di Mascio et al. in A second order Godunov—type scheme for naval hydrodynamics, Kluwer Academic/Plenum Publishers, Dordrecht, pp 253-261, 2001; Proceedings of 16th international offshore and polar engineering conference, San Francisco, CA, USA, 2006; J Mar Sci Technol 14:19-29, 2009); air/water interface dynamics is accurately modeled by a non standard level set approach (Di Mascio et al. in Comput Fluids 36(5):868-886, 2007a), known as the single-phase level set method. In this algorithm the governing equations are solved only in the water phase, whereas the numerical domain in the air phase is used for a suitable extension of the fluid dynamic variables. The level set function is used to track the free surface evolution; dynamic boundary conditions are enforced directly on the interface. This approach allows to accurately predict the evolution of the free surface even in the presence of violent breaking waves phenomena, maintaining the interface sharp, without any need to smear out the fluid properties across the two phases. This paper is aimed at the prediction of the complex free-surface flow field generated by a deep-V planing boat at medium and high Froude numbers (from 0.6 up to 1.2). In the present work, the planing hull is treated as a two-degree-of-freedom rigid object. Flow field is characterized by the presence of thin water sheets, several energetic breaking waves and plungings. The computational results include convergence of the trim angle, sinkage and resistance under grid refinement; high-quality experimental data are used for the purposes of validation, allowing to

  6. High speed network sampling

    OpenAIRE

    Rindalsholt, Ole Arild

    2005-01-01

    Master i nettverks- og systemadministrasjon Classical Sampling methods play an important role in the current practice of Internet measurement. With today’s high speed networks, routers cannot manage to generate complete Netflow data for every packet. They have to perform restricted sampling. This thesis summarizes some of the most important sampling schemes and their applications before diving into an analysis on the effect of sampling Netflow records.

  7. High speed rotary drum

    Energy Technology Data Exchange (ETDEWEB)

    Sagara, H

    1970-03-25

    A high speed rotary drum is disclosed in which the rotor vessel is a double-wall structure comprising an inner wave-shaped pipe inserted coaxially within an outer straight pipe, the object being to provide a strengthened composite light-weight structure. Since force induced axial deformation of the straight pipe and radial deformation of the corrugated pipe are small, the composite effectively resists external forces and, if the waves of the inner pipe are given a sufficient amplitude, the thickness of both pipes may be reduced to lower the overall weight. Thus high angular velocities can be obtained to separate U/sup 235/ from gaseous UF/sub 6/.

  8. High Speed Photomicrography

    Science.gov (United States)

    Hyzer, William G.

    1983-03-01

    One of the most challenging areas in applying high-speed photography and videography in the plant and laboratory is in the recording of rapid events at macro and microscopic scales. Depth of field, exposure efficiency, working distance, and required exposure time are all reduced as optical magnification is increased, which severely taxes the skill and ingenuity of workers interested in recording any fast moving phenomena through the microscope or with magnifying lenses. This paper defines the problems inherent in photographing within macro and microscopic ranges and offers a systematic approach to optimizing the selection of equipment and choice of applicable techniques.

  9. Hydraulic performance numerical simulation of high specific speed mixed-flow pump based on quasi three-dimensional hydraulic design method

    International Nuclear Information System (INIS)

    Zhang, Y X; Su, M; Hou, H C; Song, P F

    2013-01-01

    This research adopts the quasi three-dimensional hydraulic design method for the impeller of high specific speed mixed-flow pump to achieve the purpose of verifying the hydraulic design method and improving hydraulic performance. Based on the two families of stream surface theory, the direct problem is completed when the meridional flow field of impeller is obtained by employing iterative calculation to settle the continuity and momentum equation of fluid. The inverse problem is completed by using the meridional flow field calculated in the direct problem. After several iterations of the direct and inverse problem, the shape of impeller and flow field information can be obtained finally when the result of iteration satisfies the convergent criteria. Subsequently the internal flow field of the designed pump are simulated by using RANS equations with RNG k-ε two-equation turbulence model. The static pressure and streamline distributions at the symmetrical cross-section, the vector velocity distribution around blades and the reflux phenomenon are analyzed. The numerical results show that the quasi three-dimensional hydraulic design method for high specific speed mixed-flow pump improves the hydraulic performance and reveal main characteristics of the internal flow of mixed-flow pump as well as provide basis for judging the rationality of the hydraulic design, improvement and optimization of hydraulic model

  10. Analysis of Metal Flow Behavior and Residual Stress Formation of Complex Functional Profiles under High-Speed Cold Roll-Beating

    Directory of Open Access Journals (Sweden)

    Fengkui Cui

    2018-01-01

    Full Text Available To obtain a good surface layer performance of the complex functional profile during the high-speed cold roll-beating forming process, this paper analyzed the metal plastic flow and residual stress-formed mechanism by using a theoretical model of the metal flow and residual stress generation. By using simulation software, the cold roll-beating forming process of a spline shaft was simulated and analyzed. The metal flow and residual stress formation law in the motion were researched. In a practical experiment, the changes in the grains in the spline tooth profile section and the residual stress distribution on the tooth profile were studied. A microcorrespondence relationship was established between the metal plastic flow and the residual stress generation. The conclusions indicate that the rate at which the metal flow decreases changes gradually at different metal layers. The residual stress value is directly related to the plastic flow difference. As the roll-beating speed increases, the uneven degree of plastic deformation at the workpiece surface increases, and the residual stress in the tooth profile is generally greater. At the same roll-beating speed, the rate change trend of the metal flow decreases gradually from the surface to the inner layer and from the dedendum to the addendum. The residual stress distribution on the surface of the tooth profile decreases from the dedendum to the addendum. These findings provide a basis and guidance for the controlled use of residual stress, obtaining better surface layer quality in the high-speed cold roll-beating process of the complex functional profile.

  11. Advanced high speed X-ray CT scanner for measurement and visualization of multi-phase flow

    International Nuclear Information System (INIS)

    Hori, Keiichi; Fujimoto, Tetsuro; Kawanishi, Kohei; Nishikawa, Hideo

    1998-01-01

    The development of an ultra-fast X-ray computed tomography (CT) scanner has been performed. The object of interest is in a transient or unsettled state, which makes the conventional CT scanner inappropriate. A concept of electrical switching of electron beam of X-ray generation unit is adopted to reduce the scanning time instead of a mechanical motion adopted by a conventional CT scanner. The mechanical motion is a major obstacle to improve the scanning speed. A prototype system with a scanning time of 3.6 milliseconds was developed at first. And, the feasibility was confirmed to measure the dynamic events of two-phase flow. However, faster scanning speed is generally required for the practical use in the thermalhydraulics research field. Therefore, the development of advanced type has been performed. This advanced type can operate under the scanning time of 0.5 milliseconds and is applicable for the measurement of the multi-phase flow with velocity up to 4-5 m/s. (author)

  12. Wire-mesh sensor, ultrasound and high-speed videometry applied for the characterization of horizontal gas-liquid slug flow

    Science.gov (United States)

    Ofuchi, C. Y.; Morales, R. E. M.; Arruda, L. V. R.; Neves, F., Jr.; Dorini, L.; do Amaral, C. E. F.; da Silva, M. J.

    2012-03-01

    Gas-liquid flows occur in a broad range of industrial applications, for instance in chemical, petrochemical and nuclear industries. Correct understating of flow behavior is crucial for safe and optimized operation of equipments and processes. Thus, measurement of gas-liquid flow plays an important role. Many techniques have been proposed and applied to analyze two-phase flows so far. In this experimental research, data from a wire-mesh sensor, an ultrasound technique and high-speed camera are used to study two-phase slug flows in horizontal pipes. The experiments were performed in an experimental two-phase flow loop which comprises a horizontal acrylic pipe of 26 mm internal diameter and 9 m length. Water and air were used to produce the two-phase flow and their flow rates are separately controlled to produce different flow conditions. As a parameter of choice, translational velocity of air bubbles was determined by each of the techniques and comparatively evaluated along with a mechanistic flow model. Results obtained show good agreement among all techniques. The visualization of flow obtained by the different techniques is also presented.

  13. High speed metal removal

    Science.gov (United States)

    Pugh, R. F.; Pohl, R. F.

    1982-10-01

    Four types of steel (AISI 1340, 4140, 4340, and HF-1) which are commonly used in large caliber projectile manufacture were machined at different hardness ranges representing the as-forged and the heat treated condition with various ceramic tools using ceramic coated tungsten carbide as a reference. Results show that machining speeds can be increased significantly using present available tooling.

  14. Turbulence modification in bubbly upward pipe flow. Extraction of time resolved turbulent microscopic structure by high speed PIV

    International Nuclear Information System (INIS)

    Yoshimura, Koki; Minato, Daiju; Sato, Yohei; Hishida, Koichi

    2004-01-01

    The objective of the present study is to obtain detailed information on the effects of bubbles on modification of turbulent structure by time-series measurements using a high speed time-resolved PIV. The experiments were carried out in a fully-developed vertical pipe with upflow of water at the Reynolds number of 9700 and the void fraction of 0.5%. It is observed that turbulence production was decreased and the dissipation rate was enhanced in the whole domain. We analyzed the effects of bubbles on modification of the energy cascade process from power spectra of velocity fluctuation of the continuous phase. (author)

  15. High-speed AC motors

    Energy Technology Data Exchange (ETDEWEB)

    Jokinen, T.; Arkkio, A. [Helsinki University of Technology Laboratory of Electromechanics, Otaniemi (Finland)

    1997-12-31

    The paper deals with various types of highspeed electric motors, and their limiting powers. Standard machines with laminated rotors can be utilised if the speed is moderate. The solid rotor construction makes it possible to reach higher power and speed levels than those of laminated rotors. The development work on high-speed motors done at Helsinki University of Technology is presented, too. (orig.) 12 refs.

  16. Application of the ultrasonic technique and high-speed filming for the study of the structure of air-water bubbly flows

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, R.D.M.; Venturini, O.J.; Tanahashi, E.I. [Universidade Federal de Itajuba (UNIFEI), Itajuba (Brazil); Neves, F. Jr. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba (Brazil); Franca, F.A. [Universidade Estadual de Campinas (UNICAMP), Campinas (Brazil)

    2009-10-15

    Multiphase flows are very common in industry, oftentimes involving very harsh environments and fluids. Accordingly, there is a need to determine the dispersed phase holdup using noninvasive fast responding techniques; besides, knowledge of the flow structure is essential for the assessment of the transport processes involved. The ultrasonic technique fulfills these requirements and could have the capability to provide the information required. In this paper, the potential of the ultrasonic technique for application to two-phase flows was investigated by checking acoustic attenuation data against experimental data on the void fraction and flow topology of vertical, upward, air-water bubbly flows in the zero to 15% void fraction range. The ultrasonic apparatus consisted of one emitter/receiver transducer and three other receivers at different positions along the pipe circumference; simultaneous high-speed motion pictures of the flow patterns were made at 250 and 1000 fps. The attenuation data for all sensors exhibited a systematic interrelated behavior with void fraction, thereby testifying to the capability of the ultrasonic technique to measure the dispersed phase holdup. From the motion pictures, basic gas phase structures and different flows patterns were identified that corroborated several features of the acoustic attenuation data. Finally, the acoustic wave transit time was also investigated as a function of void fraction. (author)

  17. SEAL FOR HIGH SPEED CENTRIFUGE

    Science.gov (United States)

    Skarstrom, C.W.

    1957-12-17

    A seal is described for a high speed centrifuge wherein the centrifugal force of rotation acts on the gasket to form a tight seal. The cylindrical rotating bowl of the centrifuge contains a closure member resting on a shoulder in the bowl wall having a lower surface containing bands of gasket material, parallel and adjacent to the cylinder wall. As the centrifuge speed increases, centrifugal force acts on the bands of gasket material forcing them in to a sealing contact against the cylinder wall. This arrangememt forms a simple and effective seal for high speed centrifuges, replacing more costly methods such as welding a closure in place.

  18. Electromagnetic application device for flow rate/flow speed control

    International Nuclear Information System (INIS)

    Yoshioka, Senji.

    1994-01-01

    Electric current and magnetic field are at first generated in a direction perpendicular to a flow channel of a fluid, and forces generated by electromagnetic interaction of the current and the magnetic field are combined and exerted on the fluid, to control the flow rate and the flow speed thereby decreasing flowing pressure loss. In addition, an electric current generation means and a magnetic field generation means integrated together are disposed to a structural component constituting the flow channel, and they are combined to attain the aimed effect. The current generating means forms a potential difference by supplying electric power to a pair of electrodes as a cathode and an anode by using structures disposed along the channel, to generate an electric field or electric current in a direction perpendicular to the flow channel. The magnetic field generating means forms a counter current (reciprocal current) by using structures disposed along the flow channel, to generate synthesized or emphasized magnetic field. The fluid can be applied with a force in the direction of the flowing direction by the electromagnetic interaction of the electric current and the magnetic field, thereby capable of propelling the fluid. Accordingly, the flowrate/flowing speed can be controlled inside of the flow channel and flowing pressure loss can be decreased. (N.H.)

  19. COMPUTER MODELING IN DEFORM-3D FOR ANALYSIS OF PLASTIC FLOW IN HIGH-SPEED HOT EXTRUSION OF BIMETALLIC FORMATIVE PARTS OF DIE TOOLING

    Directory of Open Access Journals (Sweden)

    I. V. Kachanov

    2015-01-01

    Full Text Available The modern development of industrial production is closely connected with the use of science-based and high technologies to ensure competitiveness of the manufactured products on the world market. There is also much tension around an energy- and resource saving problem which can be solved while introducing new technological processes and  creation of new materials that provide productivity increase through automation and improvement of tool life. Development and implementation of such technologies are rather often considered as time-consuming processes  which are connected with complex calculations and experimental investigations. Implementation of a simulation modelling for materials processing using modern software products serves an alternative to experimental and theoretical methods of research.The aim of this paper is to compare experimental results while obtaining bimetallic samples of a forming tool through the method of speed hot extrusion and the results obtained with the help of computer simulation using DEFORM-3D package and a finite element method. Comparative analysis of plastic flow of real and model samples has shown that the obtained models provide high-quality and reliable picture of plastic flow during high-speed hot extrusion. Modeling in DEFORM-3D make it possible to eliminate complex calculations and significantly reduce a number of experimental studies while developing new technological processes.

  20. Development and Implementation of 3-D, High Speed Capacitance Tomography for Imaging Large-Scale, Cold-Flow Circulating Fluidized Bed

    Energy Technology Data Exchange (ETDEWEB)

    Marashdeh, Qussai [Tech4imaging LLC, Columbus, OH (United States)

    2013-02-01

    A detailed understanding of multiphase flow behavior inside a Circulating Fluidized Bed (CFB) requires a 3-D technique capable of visualizing the flow field in real-time. Electrical Capacitance Volume Tomography (ECVT) is a newly developed technique that can provide such measurements. The attractiveness of the technique is in its low profile sensors, fast imaging speed and scalability to different section sizes, low operating cost, and safety. Moreover, the flexibility of ECVT sensors enable them to be designed around virtually any geometry, rendering them suitable to be used for measurement of solid flows in exit regions of the CFB. Tech4Imaging LLC has worked under contract with the U.S. Department of Energy's National Energy Technology Laboratory (DOE NETL) to develop an ECVT system for cold flow visualization and install it on a 12 inch ID circulating fluidized bed. The objective of this project was to help advance multi-phase flow science through implementation of an ECVT system on a cold flow model at DOE NETL. This project has responded to multi-phase community and industry needs of developing a tool that can be used to develop flow models, validate computational fluid dynamics simulations, provide detailed real-time feedback of process variables, and provide a comprehensive understating of multi-phase flow behavior. In this project, a complete ECVT system was successfully developed after considering different potential electronics and sensor designs. The system was tested at various flow conditions and with different materials, yielding real-time images of flow interaction in a gas-solid flow system. The system was installed on a 12 inch ID CFB of the US Department of Energy, Morgantown Labs. Technical and economic assessment of Scale-up and Commercialization of ECVT was also conducted. Experiments conducted with larger sensors in conditions similar to industrial settings are very promising. ECVT has also the potential to be developed for imaging multi

  1. Flow Studies of Decelerators at Supersonic Speeds

    Science.gov (United States)

    1959-01-01

    Wind tunnel tests recorded the effect of decelerators on flow at various supersonic speeds. Rigid parachute models were tested for the effects of porosity, shroud length, and number of shrouds. Flexible model parachutes were tested for effects of porosity and conical-shaped canopy. Ribbon dive brakes on a missile-shaped body were tested for effect of tension cable type and ribbon flare type. The final test involved a plastic sphere on riser lines.

  2. Direct numerical simulation of a compressible boundary-layer flow past an isolated three-dimensional hump in a high-speed subsonic regime

    Science.gov (United States)

    De Grazia, D.; Moxey, D.; Sherwin, S. J.; Kravtsova, M. A.; Ruban, A. I.

    2018-02-01

    In this paper we study the boundary-layer separation produced in a high-speed subsonic boundary layer by a small wall roughness. Specifically, we present a direct numerical simulation (DNS) of a two-dimensional boundary-layer flow over a flat plate encountering a three-dimensional Gaussian-shaped hump. This work was motivated by the lack of DNS data of boundary-layer flows past roughness elements in a similar regime which is typical of civil aviation. The Mach and Reynolds numbers are chosen to be relevant for aeronautical applications when considering small imperfections at the leading edge of wings. We analyze different heights of the hump: The smaller heights result in a weakly nonlinear regime, while the larger result in a fully nonlinear regime with an increasing laminar separation bubble arising downstream of the roughness element and the formation of a pair of streamwise counterrotating vortices which appear to support themselves.

  3. High speed capillary zone electrophoresis-mass spectrometry via an electrokinetically pumped sheath flow interface for rapid analysis of amino acids and a protein digest.

    Science.gov (United States)

    Schiavone, Nicole M; Sarver, Scott A; Sun, Liangliang; Wojcik, Roza; Dovichi, Norman J

    2015-06-01

    While capillary zone electrophoresis (CZE) has been used to produce very rapid and efficient separations, coupling these high-speed separations with mass spectrometry (MS) has been challenging. Now, with much faster and sensitive mass spectrometers, it is possible to take full advantage of the CZE speed and reconstruct the fast migrating peaks. Here are three high-speed CZE-MS analyses via an electrokinetically pumped sheath-flow interface. The first separation demonstrates CZE-ESI-MS of an amino acid mixture with a 2-min separation, >50,000 theoretical plates, low micromolar concentration detection limits, and subfemtomole mass detection limits (LTQ XL mass spectrometer). The second separation with our recently improved third-generation CE-MS interface illustrates a 20 amino acid separation in ∼7min with an average over 200,000 plate counts, and results in almost-baseline resolution of structural isomers, leucine and isoleucine. The third separation is of a BSA digest with a reproducible CZE separation and mass spectrometry detection in 2min. CZE-MS/MS analysis of the BSA digest identified 31 peptides, produced 52% sequence coverage, and generated a peak capacity of ∼40 across the 1-min separation window (Q-Exactive mass spectrometer). Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Predation by the Dwarf Seahorse on Copepods: Quantifying Motion and Flows Using 3D High Speed Digital Holographic Cinematography - When Seahorses Attack!

    Science.gov (United States)

    Gemmell, Brad; Sheng, Jian; Buskey, Ed

    2008-11-01

    Copepods are an important planktonic food source for most of the world's fish species. This high predation pressure has led copepods to evolve an extremely effective escape response, with reaction times to hydrodynamic disturbances of less than 4 ms and escape speeds of over 500 body lengths per second. Using 3D high speed digital holographic cinematography (up to 2000 frames per second) we elucidate the role of entrainment flow fields generated by a natural visual predator, the dwarf seahorse (Hippocampus zosterae) during attacks on its prey, Acartia tonsa. Using phytoplankton as a tracer, we recorded and reconstructed 3D flow fields around the head of the seahorse and its prey during both successful and unsuccessful attacks to better understand how some attacks lead to capture with little or no detection from the copepod while others result in failed attacks. Attacks start with a slow approach to minimize the hydro-mechanical disturbance which is used by copepods to detect the approach of a potential predator. Successful attacks result in the seahorse using its pipette-like mouth to create suction faster than the copepod's response latency. As these characteristic scales of entrainment increase, a successful escape becomes more likely.

  5. High Speed Schlieren Studies of Flow Over Mercury Atlas Vehicle in the Langley 2-Foot Transonic Aeroplasticity Tunnel

    Science.gov (United States)

    1960-01-01

    Test conditions for the studies are: Mach number varying continuously from approximately 0.8 to 1.1 and Reynolds number (based on maximum diameter of Atlas) approximately 0.451 x 10(exp 6). Camera speed is 2000 frames per second.

  6. Heat-flux gage measurements on a flat plate at a Mach number of 4.6 in the VSD high speed wind tunnel, a feasibility test (LA28). [wind tunnel tests of measuring instruments for boundary layer flow

    Science.gov (United States)

    1975-01-01

    The feasibility of employing thin-film heat-flux gages was studied as a method of defining boundary layer characteristics at supersonic speeds in a high speed blowdown wind tunnel. Flow visualization techniques (using oil) were employed. Tabulated data (computer printouts), a test facility description, and photographs of test equipment are given.

  7. Small Sub-micron-Particle Position-Resolving Laser-Doppler Velocimeter for High-Speed Flows, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The technical objectives of this proposed work are to develop and prove the use of LDV and CompLDV for particle-position-resolving and flow velocity profile...

  8. Development and Application of Advanced Optical Diagnostics for the Study of High Speed Flows in Micro Systems

    National Research Council Canada - National Science Library

    Lempert, Walter

    2000-01-01

    .... In particular, Molecular Tagging Velocimetry (MTV) measurements have been performed, using acetone vapor as a molecular tracer, in the flow produced by a 1 mm diameter, pressure matched, sonic nozzle...

  9. Experimental investigation of the effects of heat release on mixing processes and flow structure in a high-speed subsonic turbulent H{sub 2} jet

    Energy Technology Data Exchange (ETDEWEB)

    Theron, M.; Bellenoue, M. [Laboratoire de Combustion et de Detonique, CNRS UPR 9028, Poitiers (France)

    2006-06-15

    In this paper, we explore the effects of heat release on mixing and flow structure in a high-speed subsonic turbulent H{sub 2} jet in an air coflow. Heat release effects are determined from the comparison of nonreacting and reacting jet behavior, boundary conditions being identical in both cases. Experiments are performed in a wind tunnel specifically designed for this purpose. Planar laser induced fluorescence on OH radicals and on acetone (seeded in the hydrogen jet) are used to characterize the cartography of scalars, and laser Doppler velocimetry is used to characterize velocity profiles in the far field of the H{sub 2} jet. Results show significant effects of heat release on mixing and flow structure, indicating an overall reduction of mixing and entrainment in the reacting jet compared to the nonreacting jet. First, a change is observed in the orientation of coherent structures originating from Kelvin-Helmholtz type instabilities, and responsible for air entrainment within the jet, which appear 'flatter' in the jet flame. Then, the flame length is increased over what would be predicted from the intersection of the mean stoichiometric contour with the centerline of the nonreacting jet. And finally, the longitudinal average velocity decrease along the jet axis is quicker in the nonreacting jet, and nondimensional transverse velocity fluctuations are about half as high in the reacting jet as in the nonreacting jet, indicating a reduction of the turbulence intensity of the flow in this direction in the jet flame. (author)

  10. High-speed holographic camera

    International Nuclear Information System (INIS)

    Novaro, Marc

    The high-speed holographic camera is a disgnostic instrument using holography as an information storing support. It allows us to take 10 holograms, of an object, with exposures times of 1,5ns, separated in time by 1 or 2ns. In order to get these results easily, no mobile part is used in the set-up [fr

  11. Pulsed laser triggered high speed microfluidic switch

    Science.gov (United States)

    Wu, Ting-Hsiang; Gao, Lanyu; Chen, Yue; Wei, Kenneth; Chiou, Pei-Yu

    2008-10-01

    We report a high-speed microfluidic switch capable of achieving a switching time of 10 μs. The switching mechanism is realized by exciting dynamic vapor bubbles with focused laser pulses in a microfluidic polydimethylsiloxane (PDMS) channel. The bubble expansion deforms the elastic PDMS channel wall and squeezes the adjacent sample channel to control its fluid and particle flows as captured by the time-resolved imaging system. A switching of polystyrene microspheres in a Y-shaped channel has also been demonstrated. This ultrafast laser triggered switching mechanism has the potential to advance the sorting speed of state-of-the-art microscale fluorescence activated cell sorting devices.

  12. High speed laser tomography system

    Science.gov (United States)

    Samsonov, D.; Elsaesser, A.; Edwards, A.; Thomas, H. M.; Morfill, G. E.

    2008-03-01

    A high speed laser tomography system was developed capable of acquiring three-dimensional (3D) images of optically thin clouds of moving micron-sized particles. It operates by parallel-shifting an illuminating laser sheet with a pair of galvanometer-driven mirrors and synchronously recording two-dimensional (2D) images of thin slices of the imaged volume. The maximum scanning speed achieved was 120000slices/s, sequences of 24 volume scans (up to 256 slices each) have been obtained. The 2D slices were stacked to form 3D images of the volume, then the positions of the particles were identified and followed in the consecutive scans. The system was used to image a complex plasma with particles moving at speeds up to cm/s.

  13. High speed photography of the plasma flow and the projectiles in the T.U.M. hypervelocity accelerator

    International Nuclear Information System (INIS)

    Igenbergs, E.; Kuczera, H.; Schroeder, B.

    1979-01-01

    The hypervelocity accelerator at the Technische Universitaet Muenchen, FRG, accelerates small projectiles (0.1 to 1.0 mm diameter) to velocities around 20 km/s. The photographic equipment consists of two Cordin single-frame image converter cameras and one TRW image converter camera with streak units and multiple-frame units. They are used for plasma flow diagnostics and the measurement of the position and the velocity of the projectiles. The single-frame cameras are triggered with a Laser light bar and the photographic measurement of the projectile velocity will be compared with Doppler-Radar. (author)

  14. Experimental Studies of the Aerothermal Characteristics of the Project Orion CEV heat Shield in High Speed Transitional and Turbulent Flows

    Science.gov (United States)

    Wadhams, T.P.; MacLean, M.; Holden, M.S.; Cassady, A.M.

    2009-01-01

    An experimental program has been completed by CUBRC exploring laminar, transitional, and turbulent flows over a 7.0% scale model of the Project ORION CEV geometry. This program was executed primarily to answer questions concerning the increase in heat transfer on the windward, or "hot shoulder" of the CEV heat shield from laminar to turbulent flow. To answer these questions CUBRC constructed and instrumented a 14.0 inch diameter Project ORION CEV model and ran a range of Reynolds numbers based on diameter from 1.0 to over 40 million at a Mach number of 8.0. These Reynolds numbers were selected to cover laminar to turbulent heating data on the "hot shoulder". Data obtained during these runs will be used to guide design decisions as they apply to heat shield thickness and extent. Several experiments at higher enthalpies were achieved to obtain data for code validation with real gas effects and transition. CUBRC also performed computation studies of these experiments to aid in the data reduction process and study turbulence modeling.

  15. High-speed parallel counter

    International Nuclear Information System (INIS)

    Gus'kov, B.N.; Kalinnikov, V.A.; Krastev, V.R.; Maksimov, A.N.; Nikityuk, N.M.

    1985-01-01

    This paper describes a high-speed parallel counter that contains 31 inputs and 15 outputs and is implemented by integrated circuits of series 500. The counter is designed for fast sampling of events according to the number of particles that pass simultaneously through the hodoscopic plane of the detector. The minimum delay of the output signals relative to the input is 43 nsec. The duration of the output signals can be varied from 75 to 120 nsec

  16. Cross-sectional void fraction distribution measurements in a vertical annulus two-phase flow by high speed X-ray computed tomography and real-time neutron radiography techniques

    International Nuclear Information System (INIS)

    Harvel, G.D.; Hori, K.; Kawanishi, K.

    1995-01-01

    A Real-Time Neutron Radiography (RTNR) system and a high speed X-ray Computed tomography (X-CT) system are compared for measurement of two-phase flow. Each system is used to determine the flow regime, and the void fraction distribution in a vertical annulus flow channel. A standard optical video system is also used to observe the flow regime. The annulus flow channel is operated as a bubble column and measurements obtained for gas flow rates from 0.0 to 30.01/min. The flow regimes observed by all three measurement systems through image analysis shows that the two-dimensional void fraction distribution can be obtained. The X-CT system is shown to have a superior temporal resolution capable of resolving the void fraction distribution in an (r,θ) plane in 33.0 ms. Void fraction distribution for bubbly flow and slug flow is determined

  17. Cross-sectional void fraction distribution measurements in a vertical annulus two-phase flow by high speed X-ray computed tomography and real-time neutron radiography techniques

    Energy Technology Data Exchange (ETDEWEB)

    Harvel, G.D. [McMaster Univ., Ontario (Canada)]|[Combustion and Heat Transfer Lab., Takasago (Japan); Hori, K.; Kawanishi, K. [Combustion and Heat Transfer Lab., Takasago (Japan)] [and others

    1995-09-01

    A Real-Time Neutron Radiography (RTNR) system and a high speed X-ray Computed tomography (X-CT) system are compared for measurement of two-phase flow. Each system is used to determine the flow regime, and the void fraction distribution in a vertical annulus flow channel. A standard optical video system is also used to observe the flow regime. The annulus flow channel is operated as a bubble column and measurements obtained for gas flow rates from 0.0 to 30.01/min. The flow regimes observed by all three measurement systems through image analysis shows that the two-dimensional void fraction distribution can be obtained. The X-CT system is shown to have a superior temporal resolution capable of resolving the void fraction distribution in an (r,{theta}) plane in 33.0 ms. Void fraction distribution for bubbly flow and slug flow is determined.

  18. High speed computer assisted tomography

    International Nuclear Information System (INIS)

    Maydan, D.; Shepp, L.A.

    1980-01-01

    X-ray generation and detection apparatus for use in a computer assisted tomography system which permits relatively high speed scanning. A large x-ray tube having a circular anode (3) surrounds the patient area. A movable electron gun (8) orbits adjacent to the anode. The anode directs into the patient area xrays which are delimited into a fan beam by a pair of collimating rings (21). After passing through the patient, x-rays are detected by an array (22) of movable detectors. Detector subarrays (23) are synchronously movable out of the x-ray plane to permit the passage of the fan beam

  19. High-speed data search

    Science.gov (United States)

    Driscoll, James N.

    1994-01-01

    The high-speed data search system developed for KSC incorporates existing and emerging information retrieval technology to help a user intelligently and rapidly locate information found in large textual databases. This technology includes: natural language input; statistical ranking of retrieved information; an artificial intelligence concept called semantics, where 'surface level' knowledge found in text is used to improve the ranking of retrieved information; and relevance feedback, where user judgements about viewed information are used to automatically modify the search for further information. Semantics and relevance feedback are features of the system which are not available commercially. The system further demonstrates focus on paragraphs of information to decide relevance; and it can be used (without modification) to intelligently search all kinds of document collections, such as collections of legal documents medical documents, news stories, patents, and so forth. The purpose of this paper is to demonstrate the usefulness of statistical ranking, our semantic improvement, and relevance feedback.

  20. Effect of welding current and speed on occurrence of humping bead in high-speed GMAW

    Institute of Scientific and Technical Information of China (English)

    Chen Ji; Wu Chuansong

    2009-01-01

    The developed mathematical model of humping formation mechanism in high-speed gas metal arc welding (GMAW) is used to analyze the effects of welding current and welding speed on the occurrence of humping bead. It considers both the momentum and heat content of backward flowing molten jet inside weld pool. Three-dimensional geometry of weld pool, the spacing between two adjacent humps and hump height along humping weld bead are calculated under different levels of welding current and welding speed. It shows that wire feeding rate, power intensity and the moment of backward flowing molten jet are the major factors on humping bead formation.

  1. Speed scaling for weighted flow time

    NARCIS (Netherlands)

    Bansal, N.; Pruhs, K.R.; Stein, C.

    2007-01-01

    In addition to the traditional goal of efficiently managing time and space, many computers now need to efficiently manage power usage. For example, Intel's SpeedStep and AMD's PowerNOW technologies allow the Windows XP operating system to dynamically change the speed of the processor to prolong

  2. Experimental high-speed network

    Science.gov (United States)

    McNeill, Kevin M.; Klein, William P.; Vercillo, Richard; Alsafadi, Yasser H.; Parra, Miguel V.; Dallas, William J.

    1993-09-01

    Many existing local area networking protocols currently applied in medical imaging were originally designed for relatively low-speed, low-volume networking. These protocols utilize small packet sizes appropriate for text based communication. Local area networks of this type typically provide raw bandwidth under 125 MHz. These older network technologies are not optimized for the low delay, high data traffic environment of a totally digital radiology department. Some current implementations use point-to-point links when greater bandwidth is required. However, the use of point-to-point communications for a total digital radiology department network presents many disadvantages. This paper describes work on an experimental multi-access local area network called XFT. The work includes the protocol specification, and the design and implementation of network interface hardware and software. The protocol specifies the Physical and Data Link layers (OSI layers 1 & 2) for a fiber-optic based token ring providing a raw bandwidth of 500 MHz. The protocol design and implementation of the XFT interface hardware includes many features to optimize image transfer and provide flexibility for additional future enhancements which include: a modular hardware design supporting easy portability to a variety of host system buses, a versatile message buffer design providing 16 MB of memory, and the capability to extend the raw bandwidth of the network to 3.0 GHz.

  3. High speed all optical networks

    Science.gov (United States)

    Chlamtac, Imrich; Ganz, Aura

    1990-01-01

    An inherent problem of conventional point-to-point wide area network (WAN) architectures is that they cannot translate optical transmission bandwidth into comparable user available throughput due to the limiting electronic processing speed of the switching nodes. The first solution to wavelength division multiplexing (WDM) based WAN networks that overcomes this limitation is presented. The proposed Lightnet architecture takes into account the idiosyncrasies of WDM switching/transmission leading to an efficient and pragmatic solution. The Lightnet architecture trades the ample WDM bandwidth for a reduction in the number of processing stages and a simplification of each switching stage, leading to drastically increased effective network throughputs. The principle of the Lightnet architecture is the construction and use of virtual topology networks, embedded in the original network in the wavelength domain. For this construction Lightnets utilize the new concept of lightpaths which constitute the links of the virtual topology. Lightpaths are all-optical, multihop, paths in the network that allow data to be switched through intermediate nodes using high throughput passive optical switches. The use of the virtual topologies and the associated switching design introduce a number of new ideas, which are discussed in detail.

  4. Aeroacoustic modelling of low-speed flows

    Energy Technology Data Exchange (ETDEWEB)

    Wen Zhong Shen; Noerkaer Soerensen, Jens

    1998-08-01

    A new numerical algorithm for acoustic noise generation is developed. The approach involves two steps comprising an incompressible flow part and inviscid acoustic part. The acoustic part can be started at any time of the incompressible computation. The formulation can be applied both for isentropic flows and non-isentropic flows. The model is validated for the cases of an isentropic pulsating sphere and non-isentropic flows past a circular cylinder and a NACA 0015 airfoil. The computations show that the generated acoustic frequencies have the form 1/m of the basic frequency of incompressible flow. (au) 15 refs.

  5. Research on Aerodynamic Noise Reduction for High-Speed Trains

    OpenAIRE

    Zhang, Yadong; Zhang, Jiye; Li, Tian; Zhang, Liang; Zhang, Weihua

    2016-01-01

    A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES) using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD)/Ffowcs Williams-Hawkings (FW-H)...

  6. High Speed On-Wafer Characterization Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — At the High Speed On-Wafer Characterization Laboratory, researchers characterize and model devices operating at terahertz (THz) and millimeter-wave frequencies. The...

  7. High-speed motion neutron radiography

    International Nuclear Information System (INIS)

    Bossi, R.H.; Barton, J.P.; Robinson, A.H.

    1982-01-01

    A system has been developed to perform neutron radiographic analysis of dynamic events having a duration of several milliseconds. The system has been operated in the range of 2000 to 10,000 frames. Synchronization has provided high-speed motion neutron radiographs for evaluation of the firing cycles of 7.62-mm munition rounds within a thick steel rifle barrel. The system has also been used to demonstrate its ability to produce neutron radiographic movies of two-phase flow. The equipment includes a TRIGA reactor capable of pulsing to a peak power of 3000 MW, a neutron beam collimator, a scintillator neutron conversion screen coupled to an image intensifier, and a 16-mm high-speed movie camera. The peak neutron flux incident at the object position is about 4 X 10 11 n/cm 2 X s with a pulse, full-width at half-maximum, of 9 ms. Modulation transfer function techniques have been used to assist optimization of the system performance. Special studies have been performed on the scintillator conversion screens and on the effects of statistical limitations on information availability

  8. Inlet design for high-speed propfans

    Science.gov (United States)

    Little, B. H., Jr.; Hinson, B. L.

    1982-01-01

    A two-part study was performed to design inlets for high-speed propfan installation. The first part was a parametric study to select promising inlet concepts. A wide range of inlet geometries was examined and evaluated - primarily on the basis of cruise thrust and fuel burn performance. Two inlet concepts were than chosen for more detailed design studies - one apropriate to offset engine/gearbox arrangements and the other to in-line arrangements. In the second part of this study, inlet design points were chosen to optimize the net installed thrust, and detailed design of the two inlet configurations was performed. An analytical methodology was developed to account for propfan slipstream effects, transonic flow efects, and three-dimensional geometry effects. Using this methodology, low drag cowls were designed for the two inlets.

  9. High speed, High resolution terahertz spectrometers

    International Nuclear Information System (INIS)

    Kim, Youngchan; Yee, Dae Su; Yi, Miwoo; Ahn, Jaewook

    2008-01-01

    A variety of sources and methods have been developed for terahertz spectroscopy during almost two decades. Terahertz time domain spectroscopy (THz TDS)has attracted particular attention as a basic measurement method in the fields of THz science and technology. Recently, asynchronous optical sampling (AOS)THz TDS has been demonstrated, featuring rapid data acquisition and a high spectral resolution. Also, terahertz frequency comb spectroscopy (TFCS)possesses attractive features for high precision terahertz spectroscopy. In this presentation, we report on these two types of terahertz spectrometer. Our high speed, high resolution terahertz spectrometer is demonstrated using two mode locked femtosecond lasers with slightly different repetition frequencies without a mechanical delay stage. The repetition frequencies of the two femtosecond lasers are stabilized by use of two phase locked loops sharing the same reference oscillator. The time resolution of our terahertz spectrometer is measured using the cross correlation method to be 270 fs. AOS THz TDS is presented in Fig. 1, which shows a time domain waveform rapidly acquired on a 10ns time window. The inset shows a zoom into the signal with 100ps time window. The spectrum obtained by the fast Fourier Transformation (FFT)of the time domain waveform has a frequency resolution of 100MHz. The dependence of the signal to noise ratio (SNR)on the measurement time is also investigated

  10. Reducing Heating In High-Speed Cinematography

    Science.gov (United States)

    Slater, Howard A.

    1989-01-01

    Infrared-absorbing and infrared-reflecting glass filters simple and effective means for reducing rise in temperature during high-speed motion-picture photography. "Hot-mirror" and "cold-mirror" configurations, employed in projection of images, helps prevent excessive heating of scenes by powerful lamps used in high-speed photography.

  11. Reducing the impact of speed dispersion on subway corridor flow.

    Science.gov (United States)

    Qiao, Jing; Sun, Lishan; Liu, Xiaoming; Rong, Jian

    2017-11-01

    The rapid increase in the volume of subway passengers in Beijing has necessitated higher requirements for the safety and efficiency of subway corridors. Speed dispersion is an important factor that affects safety and efficiency. This paper aims to analyze the management control methods for reducing pedestrian speed dispersion in subways. The characteristics of the speed dispersion of pedestrian flow were analyzed according to field videos. The control measurements which were conducted by placing traffic signs, yellow marking, and guardrail were proposed to alleviate speed dispersion. The results showed that the methods of placing traffic signs, yellow marking, and a guardrail improved safety and efficiency for all four volumes of pedestrian traffic flow, and the best-performing control measurement was guardrails. Furthermore, guardrails' optimal position and design measurements were explored. The research findings provide a rationale for subway managers in optimizing pedestrian traffic flow in subway corridors. Copyright © 2017. Published by Elsevier Ltd.

  12. Empirical analysis of gross vehicle weight and free flow speed and consideration on its relation with differential speed limit.

    Science.gov (United States)

    Saifizul, Ahmad Abdullah; Yamanaka, Hideo; Karim, Mohamed Rehan

    2011-05-01

    Most highly motorized countries in the world have implemented different speed limits for light weight and heavy weight vehicles. The heavy vehicle speed limit is usually chosen to be lower than that of passenger cars due to the difficulty for the drivers to safely maneuver the heavy vehicle at high speed and greater impact during a crash. However, in many cases, the speed limit for heavy vehicle is set by only considering the vehicle size or category, mostly due to simplicity in enforcement. In this study, traffic and vehicular data for all vehicle types were collected using a weigh-in-motion system installed at Federal Route 54 in Malaysia. The first finding from the data showed that the weight variation for each vehicle category is considerable. Therefore, the effect of gross vehicle weight (GVW) and category of heavy vehicle on free flow speed and their interaction were analyzed using statistical techniques. Empirical analysis results showed that statistically for each type of heavy vehicle, there was a significant relationship between free flow speed of a heavy vehicle and GVW. Specifically, the results suggest that the mean and variance of free flow speed decrease with an increase GVW by the amount unrelated to size and shape for all GVW range. Then, based on the 85th percentile principle, the study proposed a new concept for setting the speed limit for heavy vehicle by incorporating GVW where a different speed limit is imposed to the heavy vehicle, not only based on vehicle classification, but also according to its GVW. Copyright © 2010 Elsevier Ltd. All rights reserved.

  13. High - speed steel for precise cased tools

    International Nuclear Information System (INIS)

    Karwiarz, J.; Mazur, A.

    2001-01-01

    The test results of high-vanadium high - speed steel (SWV9) for precise casted tools are presented. The face -milling cutters of NFCa80A type have been tested in industrial operating conditions. An average life - time of SWV9 steel tools was 3-10 times longer compare to the conventional high - speed milling cutters. Metallography of SWB9 precise casted steel revealed beneficial for tool properties distribution of primary vanadium carbides in the steel matrix. Presented results should be a good argument for wide application of high - vanadium high - speed steel for precise casted tools. (author)

  14. High-Speed Videography Instrumentation And Procedures

    Science.gov (United States)

    Miller, C. E.

    1982-02-01

    High-speed videography has been an electronic analog of low-speed film cameras, but having the advantages of instant-replay and simplicity of operation. Recent advances have pushed frame-rates into the realm of the rotating prism camera. Some characteristics of videography systems are discussed in conjunction with applications in sports analysis, and with sports equipment testing.

  15. High speed rails. Fatigue behaviour

    International Nuclear Information System (INIS)

    Duart, J. M.; Pero-Sanz, J. A.; Verdeja, J. I.

    2005-01-01

    In recent years, passenger train speed and freight train load have increased to enhance efficiency of rail road transportation. These trends have increased the severity of rail service conditions, calling for rails with greater wear resistance, strength and fatigue behaviour. In the United Stated and Europe, track site weld rails are made entirely by aluminothermic process. This work describes the results of experimental study conducted on bending fatigue strength of plain rails and aluminothermic welded rails with preheating procedures (oxipropane and air-induced propane) approved by railways authorities. Compliance with the required fatigue strength shall be ascertained by 4 point pulsating bending test in accordance with European standards by aluminothermic welding in rails. The locati method, based in the empirical Miner's law about the cumulative damage on a fatigue tested material, allows, once known the Wohler curve of the welding process in use to settle the fatigue tensile limit at 50% with only one test. The values obtained at 2.10''6 cycles for plain rails (S f =353 MPa), oxipropane preheated aluminothermic weld rails (S f =225 MPa), and propane-air induced aluminothermic weld rails (S f =210 MPa) are very similar to those resulting from test method stated in the European Standard. From our point of view and due to its ease, speediness and savings, this is the most suitable test to check the quality and compare the aluminothermic processes in use. (Author) 15 refs

  16. High resolution, high speed ultrahigh vacuum microscopy

    International Nuclear Information System (INIS)

    Poppa, Helmut

    2004-01-01

    The history and future of transmission electron microscopy (TEM) is discussed as it refers to the eventual development of instruments and techniques applicable to the real time in situ investigation of surface processes with high resolution. To reach this objective, it was necessary to transform conventional high resolution instruments so that an ultrahigh vacuum (UHV) environment at the sample site was created, that access to the sample by various in situ sample modification procedures was provided, and that in situ sample exchanges with other integrated surface analytical systems became possible. Furthermore, high resolution image acquisition systems had to be developed to take advantage of the high speed imaging capabilities of projection imaging microscopes. These changes to conventional electron microscopy and its uses were slowly realized in a few international laboratories over a period of almost 40 years by a relatively small number of researchers crucially interested in advancing the state of the art of electron microscopy and its applications to diverse areas of interest; often concentrating on the nucleation, growth, and properties of thin films on well defined material surfaces. A part of this review is dedicated to the recognition of the major contributions to surface and thin film science by these pioneers. Finally, some of the important current developments in aberration corrected electron optics and eventual adaptations to in situ UHV microscopy are discussed. As a result of all the path breaking developments that have led to today's highly sophisticated UHV-TEM systems, integrated fundamental studies are now possible that combine many traditional surface science approaches. Combined investigations to date have involved in situ and ex situ surface microscopies such as scanning tunneling microscopy/atomic force microscopy, scanning Auger microscopy, and photoemission electron microscopy, and area-integrating techniques such as x-ray photoelectron

  17. Cavitation characteristics of multihole diesel-fuel nozzles in high-speed oil flows. Diesel kikan yo nenryo tako nozzle no abura cavitation tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Yokota, M. (Shimonoseki Univ. of Fisheris, Yamaguchi (Japan)); Ito, Y. (Hachinohe Inst. of Tech., Aomori (Japan)); Aoki, H. (Xexel-Gleason U.S.A. Inc., New York (U.S.A))

    1991-07-25

    Recently, since higher velocity and higher pressure are required for diesel injection systems, cavitation behaviors in high velocity oil flows are strongly interested in such as 100 to 500 m/s for oil flow velocity and less than the cavitation factor {sigma} of 0.01. In this paper, oil cavitation characteristics at the injection part of multihole nozzles, especially on the flow characteristics, were studied systematically using fuel injection multihole nozzles for an actual use. As a result, it was clarified that subcavitation area (sub C), transition area, and supercavitation area (SC) could be existing in C{sub d}-{sigma} relation, which was similar to that specified cavitation conditions could be exisiting in the actual working area of multihole nozzles. And it was also clarified that flow coefficient C{sub d} relied on Reynolds number R{sub e} in the transition of {sigma}{ge}{sigma}{sub cr} and in {sub C} area, and mainly relied on {sigma} in SC area of {sigma}<{sigma}{sub cr}. Moreover, it was also confirmed that such tendency was similar to the one of the two-dimensional contraction of an area. 22 refs., 10 figs., 1 tab.

  18. Lubrication and cooling for high speed gears

    Science.gov (United States)

    Townsend, D. P.

    1985-01-01

    The problems and failures occurring with the operation of high speed gears are discussed. The gearing losses associated with high speed gearing such as tooth mesh friction, bearing friction, churning, and windage are discussed with various ways shown to help reduce these losses and thereby improve efficiency. Several different methods of oil jet lubrication for high speed gearing are given such as into mesh, out of mesh, and radial jet lubrication. The experiments and analytical results for the various methods of oil jet lubrication are shown with the strengths and weaknesses of each method discussed. The analytical and experimental results of gear lubrication and cooling at various test conditions are presented. These results show the very definite need of improved methods of gear cooling at high speed and high load conditions.

  19. High-Speed Sealift Technology Development Plan

    National Research Council Canada - National Science Library

    2002-01-01

    .... The purpose of the project was to define the technology investments required to enable development of the high-speed commercial and military ships needed to provide realistic future mission capabilities...

  20. Balancing High-Speed Rotors at Low Speed

    Science.gov (United States)

    Giordano, J.; Zorzi, E.

    1986-01-01

    Flexible balancing reduces vibrations at operating speeds. Highspeed rotors in turbomachines dynamically balanced at fraction of operating rotor speed. New method takes into account rotor flexible rather than rigid.

  1. Load flow analysis for variable speed offshore wind farms

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhao, Menghua; Blaabjerg, Frede

    2009-01-01

    factors such as the different wind farm configurations, the control of wind turbines and the power losses of pulse width modulation converters are considered. The DC/DC converter model is proposed and integrated into load flow algorithm by modifying the Jacobian matrix. Two iterative methods are proposed...... and integrated into the load flow algorithm: one takes into account the control strategy of converters and the other considers the power losses of converters. In addition, different types of variable speed wind turbine systems with different control methods are investigated. Finally, the method is demonstrated......A serial AC-DC integrated load flow algorithm for variable speed offshore wind farms is proposed. It divides the electrical system of a wind farm into several local networks, and different load flow methods are used for these local networks sequentially. This method is fast, more accurate, and many...

  2. Experimental and numerical studies on aerodynamical noise in a high-speed elevator. ; Effect of apron on flow around elevator car. Kosoku elevator no kuriki soon ni kansuru kenkyu. ; Kagomawari no nagare ni oyobosu apron bu no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, H.; Fukuyama, Y.; Miyasako, K.; Endo, M. (Toshiba Corp., Tokyo (Japan)); Yokono, Y. (Tokyo Institute of Technology, Tokyo (Japan). Research Laboratory of Precision Machinery and Electronics)

    1993-08-25

    For the purpose of reducing aerodynamic noise of a high-speed elevator, the flow around the elevator car was subjected to a flow visualization experiment and numerical simulation using a model simulating an elevator. The state of the flow in front of the door was observed by visualizing the field of flow around the model submerged in a water bath using a poster color tracer. Further, a wind tunnel experiment was carried out to observe the effects of flow at the side wall of the car. An oily agent using TiO2 as pigment was used for observing the pattern of oil film on the surface of the model and the observed results were recorded on a video tape. Since the oil solution is white, the place where the oil film is peeled by a strong shearing force exhibits a pattern of black color which is the color of the model substrate. Flow in front of the door is different depending on whether the car is in the upward motion or in the downward motion and affected by the presence of apron. During the downward motion of the car, the vertical vortices accompanying the flow detouring from the rear surface to the front surface of the apron are generated at both ends of the apron and thereby the streamlines are concentrated to generate accelerated flow in front of the door. Suppression of vertical voltices is important for reducing noise during downward motion. Peeled flow and vortex interference appear at the side and back of the car and forms a field of complex flow. 12 refs., 10 figs.

  3. High-speed photography. Technique and evolution

    International Nuclear Information System (INIS)

    Sanchez-Tembleque, R.

    1981-01-01

    It is intended to present some general considerations about ''Higg-speed photography'' as a tool of work common in mos research laboratories in the world. ''High-speed photography'' relies on the principles of photography of actions, that change rapidly with the time. The evolution of this technique goes along with the discovering of new phenomena in wich higher speeds are involved. At present is normal to deal with changing rates involving picoseconds times (10 -12 s) and new developments on the field of femtosecond (10 -15 s) theoretically are contemplated. (author)

  4. Chemically reactive and naturally convective high speed MHD fluid flow through an oscillatory vertical porous plate with heat and radiation absorption effect

    Directory of Open Access Journals (Sweden)

    S.M. Arifuzzaman

    2018-04-01

    Full Text Available This paper concerns with the modelling of an unsteady natural convective and higher order chemically reactive magnetohydrodynamics (MHD fluid flow with the effect of heat and radiation absorption. The flow is generated through a vertical oscillating porous plate. Boundary layer approximations is carried out to establish a flow model which represents the time dependent momentum, energy and diffusion balance equations. Before being solved numerically, the governing partial differential equations (PDEs were transformed into a set of nonlinear ordinary differential equation (ODEs by using non-similar technique. A very efficient numerical approach solves the obtained nonlinear coupled ODEs so called Explicit Finite Difference Method (EFDM. An algorithm is implemented in Compaq Visual Fortran 6.6a as a solving tool. In addition, the stability and convergence analysis (SCA is examined and shown explicitly. The advantages of SCA is its optimizes the accuracy of system parameters such as Prandtl number (Pr and Schmidt number (Sc.The velocity, temperature and concentration fields in the boundary layer region are studied in detail and the outcomes are shown in graphically with the influence of various pertinent parameters such as Grashof number (Gr, modified Grashof number (Gr, magnetic parameter (M, Darcy number (Da,Prandtl number (Pr, Schmidt number (Sc, radiation (R, heat sink (Q,radiation absorption (Q1, Eckert number (Ec, Dufour number (Du,Soret number (Sr, Schmidt number (Sc, reaction index (P and chemical reaction (Kr. Furthermore, the effect of skin friction coefficient (Cf, Nusselt number (Nu and Sherwood number (Sh are also examined graphically. Keywords: MHD, Oscillating porous plate, Radiation absorption, High order chemical reaction, EFDM

  5. Unsteady flow simulations of Pelton turbine at different rotational speeds

    Directory of Open Access Journals (Sweden)

    Minsuk Choi

    2015-11-01

    Full Text Available This article presents numerical simulations of a small Pelton turbine suitable for desalination system. A commercial flow solver was adopted to resolve difficulties in the numerical simulation for Pelton turbine such as the relative motion of the turbine runner to the injector and two-phase flow of water and air. To decrease the numerical diffusion of the water jet, a new topology with only hexagonal mesh was suggested for the computational mesh around the complex geometry of a bucket. The predicted flow coefficient, net head coefficient, and overall efficiency showed a good agreement with the experimental data. Based on the validation of the numerical results, the pattern of wet area on the bucket inner surface has been analyzed at different rotational speeds, and an attempt to find the connection between rotational speeds, torque, and efficiency has been made.

  6. Aerodynamic design on high-speed trains

    Science.gov (United States)

    Ding, San-San; Li, Qiang; Tian, Ai-Qin; Du, Jian; Liu, Jia-Li

    2016-04-01

    Compared with the traditional train, the operational speed of the high-speed train has largely improved, and the dynamic environment of the train has changed from one of mechanical domination to one of aerodynamic domination. The aerodynamic problem has become the key technological challenge of high-speed trains and significantly affects the economy, environment, safety, and comfort. In this paper, the relationships among the aerodynamic design principle, aerodynamic performance indexes, and design variables are first studied, and the research methods of train aerodynamics are proposed, including numerical simulation, a reduced-scale test, and a full-scale test. Technological schemes of train aerodynamics involve the optimization design of the streamlined head and the smooth design of the body surface. Optimization design of the streamlined head includes conception design, project design, numerical simulation, and a reduced-scale test. Smooth design of the body surface is mainly used for the key parts, such as electric-current collecting system, wheel truck compartment, and windshield. The aerodynamic design method established in this paper has been successfully applied to various high-speed trains (CRH380A, CRH380AM, CRH6, CRH2G, and the Standard electric multiple unit (EMU)) that have met expected design objectives. The research results can provide an effective guideline for the aerodynamic design of high-speed trains.

  7. Experimental analysis of flow structure in contra-rotating axial flow pump designed with different rotational speed concept

    Science.gov (United States)

    Cao, Linlin; Watanabe, Satoshi; Imanishi, Toshiki; Yoshimura, Hiroaki; Furukawa, Akinori

    2013-08-01

    As a high specific speed pump, the contra-rotating axial flow pump distinguishes itself in a rear rotor rotating in the opposite direction of the front rotor, which remarkably contributes to the energy conversion, the reduction of the pump size, better hydraulic and cavitation performances. However, with two rotors rotating reversely, the significant interaction between blade rows was observed in our prototype contra-rotating rotors, which highly affected the pump performance compared with the conventional axial flow pumps. Consequently, a new type of rear rotor was designed by the rotational speed optimization methodology with some additional considerations, aiming at better cavitation performance, the reduction of blade rows interaction and the secondary flow suppression. The new rear rotor showed a satisfactory performance at the design flow rate but an unfavorable positive slope of the head — flow rate curve in the partial flow rate range less than 40% of the design flow rate, which should be avoided for the reliability of pump-pipe systems. In the present research, to understand the internal flow field of new rear rotor and its relation to the performances at the partial flow rates, the velocity distributions at the inlets and outlets of the rotors are firstly investigated. Then, the boundary layer flows on rotor surfaces, which clearly reflect the secondary flow inside the rotors, are analyzed through the limiting streamline observations using the multi-color oil-film method. Finally, the unsteady numerical simulations are carried out to understand the complicated internal flow structures in the rotors.

  8. High-speed centrifugation induces aggregation of extracellular vesicles.

    Science.gov (United States)

    Linares, Romain; Tan, Sisareuth; Gounou, Céline; Arraud, Nicolas; Brisson, Alain R

    2015-01-01

    Plasma and other body fluids contain cell-derived extracellular vesicles (EVs), which participate in physiopathological processes and have potential biomedical applications. In order to isolate, concentrate and purify EVs, high-speed centrifugation is often used. We show here, using electron microscopy, receptor-specific gold labelling and flow cytometry, that high-speed centrifugation induces the formation of EV aggregates composed of a mixture of EVs of various phenotypes and morphologies. The presence of aggregates made of EVs of different phenotypes may lead to erroneous interpretation concerning the existence of EVs harbouring surface antigens from different cell origins.

  9. High-speed centrifugation induces aggregation of extracellular vesicles

    Directory of Open Access Journals (Sweden)

    Romain Linares

    2015-12-01

    Full Text Available Plasma and other body fluids contain cell-derived extracellular vesicles (EVs, which participate in physiopathological processes and have potential biomedical applications. In order to isolate, concentrate and purify EVs, high-speed centrifugation is often used. We show here, using electron microscopy, receptor-specific gold labelling and flow cytometry, that high-speed centrifugation induces the formation of EV aggregates composed of a mixture of EVs of various phenotypes and morphologies. The presence of aggregates made of EVs of different phenotypes may lead to erroneous interpretation concerning the existence of EVs harbouring surface antigens from different cell origins.

  10. High speed motion neutron radiography of dynamic events

    International Nuclear Information System (INIS)

    Robinson, A.H.; Barton, J.P.

    1983-01-01

    The development of a technique that permits neutron radiographic analysis of dynamic processes over a period lasting from one to ten milliseconds is described. The key to the technique is the use of a neutron pulse broad enough to span the duration of a brief event and intense enough to allow recording of the results on a high-speed movie film at frame rates of 10,000 frames/sec. Some typical application results in ballistic studies and two-phase flow are shown and discussed. The use of scintillator screens in the high-speed motion neutron radiography system is summarized and the statistical limitations of the technique are discussed

  11. Insights from field observations into controls on flow front speed in submarine sediment flows

    Science.gov (United States)

    Heerema, C.; Talling, P.; Cartigny, M.; Paull, C. K.; Gwiazda, R.; Clare, M. A.; Parsons, D. R.; Xu, J.; Simmons, S.; Maier, K. L.; Chapplow, N.; Gales, J. A.; McGann, M.; Barry, J.; Lundsten, E. M.; Anderson, K.; O'Reilly, T. C.; Rosenberger, K. J.; Sumner, E. J.; Stacey, C.

    2017-12-01

    Seafloor avalanches of sediment called turbidity currents are one of the most important processes for moving sediment across our planet. Only rivers carry comparable amounts of sediment across such large areas. Here we present some of the first detailed monitoring of these underwater flows that is being undertaken at a series of test sites. We seek to understand the factors that determine flow front speed, and how that speed varies with distance. This frontal speed is particularly important for predicting flow runout, and how the power of these hazardous flows varies with distance. First, we consider unusually detailed measurements of flow front speed defined by transit times between moorings and other tracked objects placed on the floor of Monterey Canyon offshore California in 2016-17. These measurements are then compared to flow front speeds measured using multiple moorings in Bute Inlet, British Columbia in 2016; and by cable breaks in Gaoping Canyon offshore Taiwan in 2006 and 2009. We seek to understand how flow front velocity is related to seafloor gradient, flow front thickness and density. It appears that the spatial evolution of frontal speed is similar in multiple flows, although their peak frontal velocities vary. Flow front velocity tends to increase rapidly initially before declining rather gradually over tens or even hundreds of kilometres. It has been proposed that submarine flows will exist in one of two states; either eroding and accelerating, or depositing sediment and dissipating. We conclude by discussing the implications of this global compilation of flow front velocities for understanding submarine flow behaviour.

  12. Design of high-speed ECT and ERT system

    International Nuclear Information System (INIS)

    Wang Baoliang; Huang Zhiyao; Li Haiqing

    2009-01-01

    Process tomography technique provides a novel method to investigate the multi-phase flow distribution inside pipe or vessel. Electrical resistance tomography (ERT) and electrical capacitance tomography (ECT) are extensively studied in recent years. As the capacitance to voltage and resistance to voltage converters run faster, the speeds of other circuits in the system, such as MCU, A/D, D/A etc, have become the bottlenecks of improving the speed. This paper describes a new dual-modal, ECT and ERT, data acquisition system. The system is controlled by a digital signal processor. Both the ERT and the ECT systems use one platform to simplify the system design and maintenance. The system can work at high speed which is only limited by the capacitance to voltage converter or resistance to voltage converter. Primary test results show the speed of the new system is 1400 frames/second for 16-electrode ERT and 2200 frames/second for 12-electrode ECT.

  13. A high speed digital noise generator

    Science.gov (United States)

    Obrien, J.; Gaffney, B.; Liu, B.

    In testing of digital signal processing hardware, a high speed pseudo-random noise generator is often required to simulate an input noise source to the hardware. This allows the hardware to be exercised in a manner analogous to actual operating conditions. In certain radar and communication environments, a noise generator operating at speeds in excess of 60 MHz may be required. In this paper, a method of generating high speed pseudo-random numbers from an arbitrarily specified distribution (Gaussian, Log-Normal, etc.) using a transformation from a uniform noise source is described. A noise generator operating at 80 MHz has been constructed. Different distributions can be readily obtained by simply changing the ROM set. The hardware and test results will be described. Using this approach, the generation of pseudo-random sequences with arbitrary distributions at word rates in excess of 200 MHz can be readily achieved.

  14. Loss reduction in axial-flow compressors through low-speed model testing

    Science.gov (United States)

    Wisler, D. C.

    1984-01-01

    A systematic procedure for reducing losses in axial-flow compressors is presented. In this procedure, a large, low-speed, aerodynamic model of a high-speed core compressor is designed and fabricated based on aerodynamic similarity principles. This model is then tested at low speed where high-loss regions associated with three-dimensional endwall boundary layers flow separation, leakage, and secondary flows can be located, detailed measurements made, and loss mechanisms determined with much greater accuracy and much lower cost and risk than is possible in small, high-speed compressors. Design modifications are made by using custom-tailored airfoils and vector diagrams, airfoil endbends, and modified wall geometries in the high-loss regions. The design improvements resulting in reduced loss or increased stall margin are then scaled to high speed. This paper describes the procedure and presents experimental results to show that in some cases endwall loss has been reduced by as much as 10 percent, flow separation has been reduced or eliminated, and stall margin has been substantially improved by using these techniques.

  15. High-speed cryptography and cryptanalysis

    NARCIS (Netherlands)

    Schwabe, P.

    2011-01-01

    Modern digital communication relies heavily on cryptographic protection to ensure data integrity and privacy. In order to deploy state-of-the art cryptographic primitives and protocols in real-world scenarios, one needs to highly optimize software for both speed and security. This requires careful

  16. High-speed elevators controlled by inverters

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Yoshio; Takahashi, Hideaki; Nakamura, Kiyoshi; Kinoshita, Hiroshi

    1988-10-25

    The super-high-speed elevator with superiority to 300m/min of speed, requires both the large capacity power and wide range speed controls. Therefore, in order to materialize the smooth and quiet operation characteristics, by applying the inverter control, the low torque ripple control in the low frequency range and high frequency large capacity inverting for lowering the motor in noise are necessary with their being assured of reliability. To satisfy the above necessary items, together with the development of a sine wave pulse width and frequency modulation (PWM/PFM) control system, to more precisely enable the sine wave electric current control, and 3kHz switching power converter, using a 800A power transistor module, a supervoltage control circuit under the extraordinary condition was designed. As a result of commercializing a 360m/min super-high speed inverter elevator, the power source unit, due to the effect of high power factor, could be reduced by 30% in capacity and also the higher harmonic wave including ratio could be considerably lowered to the inferiority to 5%. 2 references, 7 figures, 1 table.

  17. High Speed Wireless Signal Generation and Demodulation

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Sambaraju, Rakesh; Zibar, Darko

    We present the experimental demonstration of high speed wireless generation, up to 40 Gb/s, in the 75-110 GHz wireless band. All-optical OFDM and photonic up-conversion are used for generation and single side-band modulation with digital coherent detection for demodulation....

  18. High speed CAMAC differential branch highway driver

    International Nuclear Information System (INIS)

    McMillan, D.E.; Nelson, R.O.; Poore, R.V.; Sunier, J.W.; Ross, J.J.

    1979-01-01

    A new CAMAC branch driver is described that incorporates several unusual features which combine to give reliable, high-speed performance. These include balanced line driver/receivers, stored CAMAC command lists, 8 DMA channels, pseudo LAMS, hardware priority encoding of LAMS, and hardware-implemented Q-controlled block transfers. 3 figures

  19. High Speed SPM of Functional Materials

    Energy Technology Data Exchange (ETDEWEB)

    Huey, Bryan D. [Univ. of Connecticut, Storrs, CT (United States)

    2015-08-14

    The development and optimization of applications comprising functional materials necessitates a thorough understanding of their static and dynamic properties and performance at the nanoscale. Leveraging High Speed SPM and concepts enabled by it, efficient measurements and maps with nanoscale and nanosecond temporal resolution are uniquely feasible. This includes recent enhancements for topographic, conductivity, ferroelectric, and piezoelectric properties as originally proposed, as well as newly developed methods or improvements to AFM-based mechanical, friction, thermal, and photoconductivity measurements. The results of this work reveal fundamental mechanisms of operation, and suggest new approaches for improving the ultimate speed and/or efficiency, of data storage systems, magnetic-electric sensors, and solar cells.

  20. Architecture Of High Speed Image Processing System

    Science.gov (United States)

    Konishi, Toshio; Hayashi, Hiroshi; Ohki, Tohru

    1988-01-01

    One of architectures for a high speed image processing system which corresponds to a new algorithm for a shape understanding is proposed. And the hardware system which is based on the archtecture was developed. Consideration points of the architecture are mainly that using processors should match with the processing sequence of the target image and that the developed system should be used practically in an industry. As the result, it was possible to perform each processing at a speed of 80 nano-seconds a pixel.

  1. High-speed Maglev studies in Canada

    International Nuclear Information System (INIS)

    Atherton, D.L.; Eastham, A.R.

    1974-01-01

    This paper reports on Canadian studies of superconducting magnetic levitation and variable-speed linear synchronous motor propulsion for high-speed inter-city guided ground transport. Levitation is obtained by the interaction of vehicle-mounted superconducting magnets and the eddy currents induced in aluminium strip conductors on the guideway. Non-contact propulsion by linear synchronous motor (LSM) is obtained by using vehicle-borne superconducting magnets and powered guideway coils. A suggested guidance scheme uses a flat guideway with 'null-flux' loops overlying the LSM windings. The propulsion magnets interact with the loops and the edges of the levitation strips to provide lateral stabilization. The test facility is a 7.6m wheel, rotating with a peripheral speed of 33m/s. (author)

  2. Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines

    DEFF Research Database (Denmark)

    Pedersen, Mads M.; Larsen, Torben J.; Madsen, Helge Aa

    2017-01-01

    In this paper an alternative method to evaluate power performance and loads on wind turbines using a blade-mounted flow sensor is investigated. The hypothesis is that the wind speed measured at the blades has a high correlation with the power and loads such that a power or load assessment can...... be performed from a few hours or days of measurements. In the present study a blade-mounted five-hole pitot tube is used as the flow sensor as an alternative to the conventional approach, where the reference wind speed is either measured at a nearby met mast or on the nacelle using lidar technology or cup...... anemometers. From the flow sensor measurements, an accurate estimate of the wind speed at the rotor plane can be obtained. This wind speed is disturbed by the presence of the wind turbine, and it is therefore different from the free-flow wind speed. However, the recorded wind speed has a high correlation...

  3. High speed printing with polygon scan heads

    Science.gov (United States)

    Stutz, Glenn

    2016-03-01

    To reduce and in many cases eliminate the costs associated with high volume printing of consumer and industrial products, this paper investigates and validates the use of the new generation of high speed pulse on demand (POD) lasers in concert with high speed (HS) polygon scan heads (PSH). Associated costs include consumables such as printing ink and nozzles, provisioning labor, maintenance and repair expense as well as reduction of printing lines due to high through put. Targets that are applicable and investigated include direct printing on plastics, printing on paper/cardboard as well as printing on labels. Market segments would include consumer products (CPG), medical and pharmaceutical products, universal ID (UID), and industrial products. In regards to the POD lasers employed, the wavelengths include UV(355nm), Green (532nm) and IR (1064nm) operating within the repetition range of 180 to 250 KHz.

  4. Potential scenarios of concern for high speed rail operations

    Science.gov (United States)

    2011-03-16

    Currently, multiple operating authorities are proposing the : introduction of high-speed rail service in the United States. : While high-speed rail service shares a number of basic : principles with conventional-speed rail service, the operational : ...

  5. Data Capture Technique for High Speed Signaling

    Science.gov (United States)

    Barrett, Wayne Melvin; Chen, Dong; Coteus, Paul William; Gara, Alan Gene; Jackson, Rory; Kopcsay, Gerard Vincent; Nathanson, Ben Jesse; Vranas, Paylos Michael; Takken, Todd E.

    2008-08-26

    A data capture technique for high speed signaling to allow for optimal sampling of an asynchronous data stream. This technique allows for extremely high data rates and does not require that a clock be sent with the data as is done in source synchronous systems. The present invention also provides a hardware mechanism for automatically adjusting transmission delays for optimal two-bit simultaneous bi-directional (SiBiDi) signaling.

  6. Comparison of improved finite-difference WENO schemes for the implicit large eddy simulation of turbulent non-reacting and reacting high-speed shear flows

    International Nuclear Information System (INIS)

    Zhao, S.; Lardjane, N.; Fedioun, I.

    2014-01-01

    Improved WENO schemes, Z, M, and their combination MZ, originally designed to capture sharper discontinuities than the classical fifth order Jiang-Shu scheme does, are evaluated for the purpose of implicit large eddy simulation of free shear flows. 1D Fourier analysis of errors reveals the built-in filter and dissipative properties of the schemes, which are subsequently applied to the canonical Rayleigh-Taylor and Taylor-Green flows. Large eddy simulations of a transonic non-reacting and a supersonic reacting air/H2 jets are then performed at resolution 128 * 128 * 512, showing no significant difference in the flow statistics. However, the computational time varies from one scheme to the other, the Z scheme providing the smaller wall-time due to larger allowed time steps. (authors)

  7. Copper infiltrated high speed steels based composites

    International Nuclear Information System (INIS)

    Madej, M.; Lezanski, J.

    2003-01-01

    High hardness, mechanical strength, heat resistance and wear resistance of M3/2 high speed steel (HSS) make it an attractive material. Since technological and economical considerations are equally important, infiltration of high-speed steel skeleton with liquid cooper has proved to be a suitable technique whereby fully dense material is produced at low cost. Attempts have been made to describe the influence of the production process parameters and alloying additives, such as tungsten carbide on the microstructure and mechanical properties of copper infiltrated HSS based composites. The compositions of powder mixtures are 100% M3/2, M3/2+10% Wc, M3/2=30% WC. The powders were uniaxially cold compacted in a cylindrical die at 800 MPa. The green compacts were sintered in vacuum at 1150 o C for 60 minutes. Thereby obtained porous skeletons were subsequently infiltrated with cooper, by gravity method, in vacuum furnace at 1150 o C for 15 minutes. (author)

  8. Development of Pulse-Burst Laser Source and Digital Image Processing for Measurements of High-Speed, Time-Evolving Flow

    National Research Council Canada - National Science Library

    Miles, Richard

    2000-01-01

    ... Ti:Sapphire Laser and the demonstration of UV filtered Rayleigh scattering imaging in a supersonic jet, the fabrication/characterization of a narrow passband transmission filter, and the development of a new concept for a line imaging Raman spectrometer for flow field, combustion, and plasma diagnostics.

  9. The effect of a flat-plate-type obstacle on the thin liquid film accompanied by a high speed gas flow

    International Nuclear Information System (INIS)

    Fukano, Tohru; Kadoguchi, Katsuhiko; Kanamori, Mikio; Tominaga, Akira.

    1989-01-01

    A flatplate-type obstacle, which simulates a grid-type spacer in a nuclear reactor, is set in an air-water cocurrent stratified flow to investigate liquid film breakdown occurring near the obstacle. We made detailed visual observations and measurements of the velocity profile of the air flow and the axial distributions of liquid film thickness and static pressure near the obstacle. Experimental parameters were the inclination of the rectangular duct, the configuration of the obstacle, i.e., with and without a projection and a hole, which is bored in order to delay the onset of dry patch formation near the obstacle and the gap between the plate and the lower-wall surface. The results show that the plate itself does not promote dry patch formation but the projection, even if it is in contact with the wall surface at only one point, has a strong effect on the liquid film breakdown. In general the film breakdown occurs in front of the projection in a wide range of flow conditions due to the leading edge down-wash of the stream and due also to the rejection of water by gravitational force in the case of the upward flow in the inclined duct. By setting a hole in or in front of the projection the occurrence of the dry patch formation is delayed. (author)

  10. Liquid metal current collectors for high-speed rotating machinery

    International Nuclear Information System (INIS)

    Carr, S.L.

    1976-01-01

    Recent interest in superconducting motors and generators has created a renewed interest in homopolar machinery. Homopolar machine designs have always been limited by the need for compact, high-current, low-voltage, sliding electrical curent collectors. Conventional graphite-based solid brushes are inadequate for use in homopolar machines. Liquid metals, under certain conditions of relative sliding velocities, electrical currents, and magnetic fields are known to be capable of performing well in homopolar machines. An effort to explore the capabilities and limits of a tongue-and-groove style current collector, utilizing sodium-potassium eutectic alloy (NaK) as the working fluid in high sliding speed operation is reported here. A double current collector generator model with a 14.5-cm maximum rotor diameter, 20,000 rpm rotational capability, and electrical current carrying ability was constructed and operated successfully at a peripheral velocity of 125 m/s. The limiting factor in these experiments was a high-speed fluid-flow instability resulting in the ejection of the working fluid from the operating portions of the collectors. The effects of collector size and geometry, working fluid (NaK or water), and cover gas pressure are reported. Hydrodynamic frictional torque-speed curves are given for the two fluids and for several geometries. Electrical resistances as a function of peripheral velocity at 60 amperes are reported, and the phenomenology of the high-speed fluid-flow instabilities is discussed. The possibility of long-term high-speed operation of current collectors of the tongue-and-groove type, along with experimental and theoretical hydrodynamic friction losses at high peripheral velocities, is considered

  11. High speed imaging system for nuclear diagnostics

    International Nuclear Information System (INIS)

    Eyer, H.H.

    1976-01-01

    A high speed imaging system based on state-of-the-art photosensor arrays has been designed for use in nuclear diagnostics. The system is comprised of a front-end rapid-scan solid-state camera, a high speed digitizer, and a PCM line driver in a downhole package and a memory buffer system in a uphole trailer. The downhole camera takes a ''snapshot'' of a nuclear device created flux stream, digitizes the image and transmits it to the uphole memory system before being destroyed. The memory system performs two functions: it retains the data for local display and processing by a microprocessor, and it buffers the data for retransmission at slower rates to the LLL computational facility (NADS). The impetus for such a system as well as its operation are discussed. Also discussed are new systems under development which incorporate higher data rates and more resolution

  12. High speed imaging system for nuclear diagnostics

    International Nuclear Information System (INIS)

    Eyer, H.H.

    1976-01-01

    A high speed imaging system based on state-of-the-art photosensor arrays has been designed for use in nuclear diagnostics. The system is comprised of a front-end rapid-scan solid-state camera, a high speed digitizer, and a PCM line driver in a downhole package and a memory buffer system in an uphole trailer. The downhole camera takes a ''snapshot'' of a nuclear device created flux stream, digitizes the image and transmits it to the uphole memory system before being destroyed. The memory system performs two functions: it retains the data for local display and processing by a microprocessor, and it buffers the data for retransmission at slower rates to the LLL computational facility (NADS). The impetus for such a system as well as its operation is discussed. Also discussed are new systems under development which incorporate higher data rates and more resolution

  13. High speed VLSI neural network for high energy physics

    NARCIS (Netherlands)

    Masa, P.; Masa, P.; Hoen, K.; Hoen, Klaas; Wallinga, Hans

    1994-01-01

    A CMOS neural network IC is discussed which was designed for very high speed applications. The parallel architecture, analog computing and digital weight storage provides unprecedented computing speed combined with ease of use. The circuit classifies up to 70 dimensional vectors within 20

  14. Development of high-speed video cameras

    Science.gov (United States)

    Etoh, Takeharu G.; Takehara, Kohsei; Okinaka, Tomoo; Takano, Yasuhide; Ruckelshausen, Arno; Poggemann, Dirk

    2001-04-01

    Presented in this paper is an outline of the R and D activities on high-speed video cameras, which have been done in Kinki University since more than ten years ago, and are currently proceeded as an international cooperative project with University of Applied Sciences Osnabruck and other organizations. Extensive marketing researches have been done, (1) on user's requirements on high-speed multi-framing and video cameras by questionnaires and hearings, and (2) on current availability of the cameras of this sort by search of journals and websites. Both of them support necessity of development of a high-speed video camera of more than 1 million fps. A video camera of 4,500 fps with parallel readout was developed in 1991. A video camera with triple sensors was developed in 1996. The sensor is the same one as developed for the previous camera. The frame rate is 50 million fps for triple-framing and 4,500 fps for triple-light-wave framing, including color image capturing. Idea on a video camera of 1 million fps with an ISIS, In-situ Storage Image Sensor, was proposed in 1993 at first, and has been continuously improved. A test sensor was developed in early 2000, and successfully captured images at 62,500 fps. Currently, design of a prototype ISIS is going on, and, hopefully, will be fabricated in near future. Epoch-making cameras in history of development of high-speed video cameras by other persons are also briefly reviewed.

  15. On Multiple AER Handshaking Channels Over High-Speed Bit-Serial Bidirectional LVDS Links With Flow-Control and Clock-Correction on Commercial FPGAs for Scalable Neuromorphic Systems.

    Science.gov (United States)

    Yousefzadeh, Amirreza; Jablonski, Miroslaw; Iakymchuk, Taras; Linares-Barranco, Alejandro; Rosado, Alfredo; Plana, Luis A; Temple, Steve; Serrano-Gotarredona, Teresa; Furber, Steve B; Linares-Barranco, Bernabe

    2017-10-01

    Address event representation (AER) is a widely employed asynchronous technique for interchanging "neural spikes" between different hardware elements in neuromorphic systems. Each neuron or cell in a chip or a system is assigned an address (or ID), which is typically communicated through a high-speed digital bus, thus time-multiplexing a high number of neural connections. Conventional AER links use parallel physical wires together with a pair of handshaking signals (request and acknowledge). In this paper, we present a fully serial implementation using bidirectional SATA connectors with a pair of low-voltage differential signaling (LVDS) wires for each direction. The proposed implementation can multiplex a number of conventional parallel AER links for each physical LVDS connection. It uses flow control, clock correction, and byte alignment techniques to transmit 32-bit address events reliably over multiplexed serial connections. The setup has been tested using commercial Spartan6 FPGAs attaining a maximum event transmission speed of 75 Meps (Mega events per second) for 32-bit events at a line rate of 3.0 Gbps. Full HDL codes (vhdl/verilog) and example demonstration codes for the SpiNNaker platform will be made available.

  16. Quiet High Speed Fan II (QHSF II): Final Report

    Science.gov (United States)

    Kontos, Karen; Weir, Don; Ross, Dave

    2012-01-01

    This report details the aerodynamic, mechanical, structural design and fabrication of a Honey Engines Quiet High Speed Fan II (lower hub/tip ratio and higher specific flow than the Baseline I fan). This fan/nacelle system incorporates features such as advanced forward sweep and an advanced integrated fan/fan exit guide vane design that provides for the following characteristics: (1) Reduced noise at supersonic tip speeds, in comparison to current state-of-the-art fan technology; (2) Improved aeroelastic stability within the anticipated operating envelope; and (3) Aerodynamic performance consistent with current state-of-the-art fan technology. This fan was fabricated by Honeywell and tested in the NASA Glenn 9- by 15-Ft Low Speed Wind Tunnel for aerodynamic, aeromechanical, and acoustic performance.

  17. Measurement of bubble velocity in an air/water flow through a narrow gap by using high-speed cinematography; Ermittlung der Blasengeschwindigkeit einer Luft/Wasser-Spaltstroemung mit Hilfe der Hochgeschwindigkeitskinematographie

    Energy Technology Data Exchange (ETDEWEB)

    Koerner, S.; Friedel, L. [Technische Univ. Hamburg-Harburg, Hamburg (Germany)

    1997-12-01

    To predict the mass flow of a two phase mixture at a given pressure difference through narrow gaps, apart from the change in state of the gas phase during pressure reduction, the knowledge of the fluid dynamics on balance which occurs in the form of a relative velocity between the phases is important. These two influences were examined with the aid of high speed cinematography for a water/air bubble flow. Apart from the quick reduction in pressure due to the sudden reduction in crossection at the entry to the gap, there are no significant differences between the experimentally determined volume change in bubbles of different sizes and that calculated assuming an isothermal change in state. The mean velocity of the bubbles does not differ appreciably from that calculated assuming an homogeneous flow. [Deutsch] Zur Vorhersage des sich bei gegebener Druckdifferenz einstellenden Massenstroms eines Zweiphasengemischs durch enge Spalte ist neben der Zustandsaenderung der Gasphase waehrend der Druckabsenkung u.a. auch die Kenntnis des sich dabei einstellenden fluiddynamischen Ungleichgewichts in Form einer Relativgeschwindigkeit zwischen den Phasen von Bedeutung. Diese beiden Einfluesse wurden mit Hilfe der Hochgeschwindigkeitskinematographie fuer eine Wasser/Luft-Blasenstroemung untersucht. Abgesehen von der raschen Druckabsenkung aufgrund der ploetzlichen Querschnittsverengung im Spalteintritt treten keine nennenswerten Unterschiede zwischen den experimentell ermittelten und den unter der Annahme einer isothermen Zustandsaenderungen berechneten Volumenaenderung verschiedengrosser Blasen auf. Die mittlere Geschwindigkeit der Blasen unterscheidet sich dabei nicht wesentlich von der unter der Annahme einer homogenen Stroemung berechneten. (orig.)

  18. High speed PVD thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Beele, W. [Sulzer Metco Coatings BV (Netherlands); Eschendorff, G. [Sulzer Metco Coatings BV (Netherlands); Eldim BV (Netherlands)

    2006-07-15

    The high speed PVD process (HS-PVD) combines gas phase coating synthesis with high deposition rates. The process has been demonstrated for high purity YSZ deposited as a chemically bonded top thermal barrier with columnar structure of EB-PVD features. The process can manufacture EB-PVD like coatings that match in regards to their TGO-formation and columnar structure. Coatings with a columnar structure formed by individual columns of 1/4 of the diameter of a classical EB-PVD type TBC have been deposited. These coatings have the potential to prove a significant reduction in thermal conductivity and in erosion performance. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  19. High speed PVD thermal barrier coatings

    International Nuclear Information System (INIS)

    Beele, W.; Eschendorff, G.

    2006-01-01

    The high speed PVD process (HS-PVD) combines gas phase coating synthesis with high deposition rates. The process has been demonstrated for high purity YSZ deposited as a chemically bonded top thermal barrier with columnar structure of EB-PVD features. The process can manufacture EB-PVD like coatings that match in regards to their TGO-formation and columnar structure. Coatings with a columnar structure formed by individual columns of 1/4 of the diameter of a classical EB-PVD type TBC have been deposited. These coatings have the potential to prove a significant reduction in thermal conductivity and in erosion performance. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  20. Distributed flow sensing for closed-loop speed control of a flexible fish robot.

    Science.gov (United States)

    Zhang, Feitian; Lagor, Francis D; Yeo, Derrick; Washington, Patrick; Paley, Derek A

    2015-10-23

    Flexibility plays an important role in fish behavior by enabling high maneuverability for predator avoidance and swimming in turbulent flow. This paper presents a novel flexible fish robot equipped with distributed pressure sensors for flow sensing. The body of the robot is molded from soft, hyperelastic material, which provides flexibility. Its Joukowski-foil shape is conducive to modeling the fluid analytically. A quasi-steady potential-flow model is adopted for real-time flow estimation, whereas a discrete-time vortex-shedding flow model is used for higher-fidelity simulation. The dynamics for the flexible fish robot yield a reduced model for one-dimensional swimming. A recursive Bayesian filter assimilates pressure measurements to estimate flow speed, angle of attack, and foil camber. The closed-loop speed-control strategy combines an inverse-mapping feedforward controller based on an average model derived for periodic actuation of angle-of-attack and a proportional-integral feedback controller utilizing the estimated flow information. Simulation and experimental results are presented to show the effectiveness of the estimation and control strategy. The paper provides a systematic approach to distributed flow sensing for closed-loop speed control of a flexible fish robot by regulating the flapping amplitude.

  1. High Speed Gear Sized and Configured to Reduce Windage Loss

    Science.gov (United States)

    Kunz, Robert F. (Inventor); Medvitz, Richard B. (Inventor); Hill, Matthew John (Inventor)

    2013-01-01

    A gear and drive system utilizing the gear include teeth. Each of the teeth has a first side and a second side opposite the first side that extends from a body of the gear. For each tooth of the gear, a first extended portion is attached to the first side of the tooth to divert flow of fluid adjacent to the body of the gear to reduce windage losses that occur when the gear rotates. The gear may be utilized in drive systems that may have high rotational speeds, such as speeds where the tip velocities are greater than or equal to about 68 m/s. Some embodiments of the gear may also utilize teeth that also have second extended portions attached to the second sides of the teeth to divert flow of fluid adjacent to the body of the gear to reduce windage losses that occur when the gear rotates.

  2. Droplet deposition measurement with high-speed camera and novel high-speed liquid film sensor with high spatial resolution

    International Nuclear Information System (INIS)

    Damsohn, M.; Prasser, H.-M.

    2011-01-01

    Highlights: → Development of a sensor for time- and space-resolved droplet deposition in annular flow. → Experimental measurement of droplet deposition in horizontal annular flow to compare readings of the sensor with images of a high-speed camera when droplets are depositing unto the liquid film. → Self-adaptive signal filter based on autoregression to separate droplet impacts in the sensor signal from waves of liquid films. - Abstract: A sensor based on the electrical conductance method is presented for the measurement of dynamic liquid films in two-phase flow. The so called liquid film sensor consists of a matrix with 64 x 16 measuring points, a spatial resolution of 3.12 mm and a time resolution of 10 kHz. Experiments in a horizontal co-current air-water film flow were conducted to test the capability of the sensor to detect droplet deposition from the gas core onto the liquid film. The experimental setup is equipped with the liquid film sensor and a high speed camera (HSC) recording the droplet deposition with a sampling rate of 10 kHz simultaneously. In some experiments the recognition of droplet deposition on the sensor is enhanced by marking the droplets with higher electrical conductivity. The comparison between the HSC and the sensor shows, that the sensor captures the droplet deposition above a certain droplet diameter. The impacts of droplet deposition can be filtered from the wavy structures respectively conductivity changes of the liquid film using a filter algorithm based on autoregression. The results will be used to locally measure droplet deposition e.g. in the proximity of spacers in a subchannel geometry.

  3. Network Based High Speed Product Innovation

    DEFF Research Database (Denmark)

    Lindgren, Peter

    In the first decade of the 21st century, New Product Development has undergone major changes in the way NPD is managed and organised. This is due to changes in technology, market demands, and in the competencies of companies. As a result NPD organised in different forms of networks is predicted...... to be of ever-increasing importance to many different kinds of companies. This happens at the same times as the share of new products of total turnover and earnings is increasing at unprecedented speed in many firms and industries. The latter results in the need for very fast innovation and product development...... - a need that can almost only be resolved by organising NPD in some form of network configuration. The work of Peter Lindgren is on several aspects of network based high speed product innovation and contributes to a descriptive understanding of this phenomenon as well as with normative theory on how NPD...

  4. BLOSTREAM: A HIGH SPEED STREAM CIPHER

    Directory of Open Access Journals (Sweden)

    ALI H. KASHMAR

    2017-04-01

    Full Text Available Although stream ciphers are widely utilized to encrypt sensitive data at fast speeds, security concerns have led to a shift from stream to block ciphers, judging that the current technology in stream cipher is inferior to the technology of block ciphers. This paper presents the design of an improved efficient and secure stream cipher called Blostream, which is more secure than conventional stream ciphers that use XOR for mixing. The proposed cipher comprises two major components: the Pseudo Random Number Generator (PRNG using the Rabbit algorithm and a nonlinear invertible round function (combiner for encryption and decryption. We evaluate its performance in terms of implementation and security, presenting advantages and disadvantages, comparison of the proposed cipher with similar systems and a statistical test for randomness. The analysis shows that the proposed cipher is more efficient, high speed, and secure than current conventional stream ciphers.

  5. High-speed reconstruction of compressed images

    Science.gov (United States)

    Cox, Jerome R., Jr.; Moore, Stephen M.

    1990-07-01

    A compression scheme is described that allows high-definition radiological images with greater than 8-bit intensity resolution to be represented by 8-bit pixels. Reconstruction of the images with their original intensity resolution can be carried out by means of a pipeline architecture suitable for compact, high-speed implementation. A reconstruction system is described that can be fabricated according to this approach and placed between an 8-bit display buffer and the display's video system thereby allowing contrast control of images at video rates. Results for 50 CR chest images are described showing that error-free reconstruction of the original 10-bit CR images can be achieved.

  6. High speed drying of saturated steam

    International Nuclear Information System (INIS)

    Marty, C.; Peyrelongue, J.P.

    1993-01-01

    This paper describes the development of the drying process for the saturated steam used in the PWR nuclear plant turbines in order to prevent negative effects of water on turbine efficiency, maintenance costs and equipment lifetime. The high speed drying concept is based on rotating the incoming saturated steam in order to separate water which is more denser than the steam; the water film is then extracted through an annular slot. A multicellular modular equipment has been tested. Applications on high and low pressure extraction of various PWR plants are described (Bugey, Loviisa)

  7. Development of ultra high speed photographic system using high repetition rate visible laser

    International Nuclear Information System (INIS)

    Lee, Jong Min; Cha, Byung Hun; Kim, Sung Ho; Kim, Jung Bog; Lim, Chang Hwan; Cha, Hyung Ki; Song, Kyu Seok; Lee, Byung Deok; Rhi, Jong Hoon; Baik, Dae Hyun; Han, Jae Min; Rho, Si Pyo; Lee, Byung Cheol; Jeong, Do Yung; Choi, An Seong; Jeong, Chan Ik; Park, Dae Ung; Jeong, Sung Min; Lee, Sang Kil; Kim, Heon Jun; Jang, Rae gak; Jo, Do Hun; Park, Min Young

    1992-12-01

    The goal of this project is to develop and commercialize a high speed photographic system equipped with a high repetition rate visible laser. The developed system provides the characteristics of high time resolution and large number of frames. The system consists of 10 W air cooled CVL or a 30 W water cooled CVL, a rotating drum-type high speed camera with the framing rate of 35,000 fps, and a automatic control device. The system has the performance of 10 nsec time resolution, 35,000 fps framing rate, and 250 picture frames. The high speed photographic systems are widely applied to the fields such as high-efficient engine development, high-speed vibration analysis, shock wave propagation study, flow visualization analysis, weapon development, etc. (Author)

  8. Hydraulic development of high specific-speed pump-turbines by means of an inverse design method, numerical flow-simulation (CFD) and model testing

    International Nuclear Information System (INIS)

    Kerschberger, P; Gehrer, A

    2010-01-01

    In recent years an increased interest in pump-turbines has been recognized in the market. The rapid availability of pumped storage schemes and the benefits to the power system by peak lopping, providing reserve and rapid response for frequency control are becoming of growing advantage. In that context it is requested to develop pump-turbines that reliably stand dynamic operation modes, fast changes of the discharge rate by adjusting the variable diffuser vanes as well as fast changes from pump to turbine operation. Within the present study various flow patterns linked to the operation of a pump-turbine system are discussed. In that context pump and turbine mode are presented separately and different load cases at both operation modes are shown. In order to achieve modern, competitive pump-turbine designs it is further explained which design challenges should be considered during the geometry definition of a pump-turbine impeller. Within the present study a runner-blade profile for a low head pump-turbine has been developed. For the initial hydraulic runner-blade design, an inverse design method has been applied. Within this design procedure, a first blade geometry is generated by imposing the pressure loading-distribution and by means of an inverse 3D potential-flow-solution. The hydraulic behavior of both, pump-mode and turbine-mode is then evaluated by solving the full 3D Navier-Stokes equations in combination with a robust turbulence model. Based on this initial design the blade profile has been further optimized and redesigned considering various hydraulic pump-turbine requirements. Finally, the progress in hydraulic design is demonstrated by model test results which show a significant improvement in hydraulic performance compared to an existing reference design.

  9. Hydraulic development of high specific-speed pump-turbines by means of an inverse design method, numerical flow-simulation (CFD) and model testing

    Science.gov (United States)

    Kerschberger, P.; Gehrer, A.

    2010-08-01

    In recent years an increased interest in pump-turbines has been recognized in the market. The rapid availability of pumped storage schemes and the benefits to the power system by peak lopping, providing reserve and rapid response for frequency control are becoming of growing advantage. In that context it is requested to develop pump-turbines that reliably stand dynamic operation modes, fast changes of the discharge rate by adjusting the variable diffuser vanes as well as fast changes from pump to turbine operation. Within the present study various flow patterns linked to the operation of a pump-turbine system are discussed. In that context pump and turbine mode are presented separately and different load cases at both operation modes are shown. In order to achieve modern, competitive pump-turbine designs it is further explained which design challenges should be considered during the geometry definition of a pump-turbine impeller. Within the present study a runner-blade profile for a low head pump-turbine has been developed. For the initial hydraulic runner-blade design, an inverse design method has been applied. Within this design procedure, a first blade geometry is generated by imposing the pressure loading-distribution and by means of an inverse 3D potential-flow-solution. The hydraulic behavior of both, pump-mode and turbine-mode is then evaluated by solving the full 3D Navier-Stokes equations in combination with a robust turbulence model. Based on this initial design the blade profile has been further optimized and redesigned considering various hydraulic pump-turbine requirements. Finally, the progress in hydraulic design is demonstrated by model test results which show a significant improvement in hydraulic performance compared to an existing reference design.

  10. Design of very high speed electric generators

    International Nuclear Information System (INIS)

    Labollita, Santiago

    2008-01-01

    This work approaches the design process of an electric generator suitable for running efficiently at high speed, driven by a turbo shaft.The axial flux concept was used.For the mechanical design of the prototype, cooling capacity and mounting method were considered, looking for simplicity of the parts evolved. Neodymium-iron-boron permanent magnets were used as magnetic source.For the electrical design, a calculation tool was developed in order to predict the prototype electrical parameters and optimize its geometry.The goal was to obtain 1 kW of electric power at a speed of 100,000 rpm.The efficiency and electrical behaviour of the prototype were characterized at speeds between 2,000 rpm and 30,000 rpm and then the behaviour at the design condition was predicted by obtaining an equivalent electric circuit.The estimated load voltage was 237 V as well as an electrical efficiency of 95%.Eddy current effects were not recognized. Increase of the internal resistance and decree of inductance were observed while raising the electric frequency.Finally, an electronic system was developed in order to use the prototype as a c.c. motor. Global performance was measured according to different supply characteristic. An optimum supply voltage was found.A maximum efficiency of 63% was reached. [es

  11. Flow in a Low Specific Speed Centrifugal Pump Using PIV

    Directory of Open Access Journals (Sweden)

    Cui Dai

    2013-01-01

    Full Text Available The interflow plays important roles in centrifugal pump design. In order to study the effect of rotation and z-axis on internal flow, two-dimensional particle image velocimetry (PIV measurements have been performed to measure the steady velocity field on three planes in all impeller passages of a low specific-speed centrifugal pump. The results show that the relative velocity flows in blade passages are obviously different in terms of the positions of the blade relative to the tongue. The interaction between the impeller and tongue changes the occurrence and development of low velocity region with time. From shroud to hub, the relative velocity gradually increases, and the minimum value moves toward the suction surface. On the midplane, the magnitude increases with increased flow rate from pressure surface to suction surface, while at the shroud and hub, the measured velocity first increases with decreased flow rate from the blade pressure surface to nearly ζ = 0.5 to 0.6.

  12. Preconditioned Conjugate Gradient methods for low speed flow calculations

    Science.gov (United States)

    Ajmani, Kumud; Ng, Wing-Fai; Liou, Meng-Sing

    1993-01-01

    An investigation is conducted into the viability of using a generalized Conjugate Gradient-like method as an iterative solver to obtain steady-state solutions of very low-speed fluid flow problems. Low-speed flow at Mach 0.1 over a backward-facing step is chosen as a representative test problem. The unsteady form of the two dimensional, compressible Navier-Stokes equations are integrated in time using discrete time-steps. The Navier-Stokes equations are cast in an implicit, upwind finite-volume, flux split formulation. The new iterative solver is used to solve a linear system of equations at each step of the time-integration. Preconditioning techniques are used with the new solver to enhance the stability and the convergence rate of the solver and are found to be critical to the overall success of the solver. A study of various preconditioners reveals that a preconditioner based on the lower-upper (L-U)-successive symmetric over-relaxation iterative scheme is more efficient than a preconditioner based on incomplete L-U factorizations of the iteration matrix. The performance of the new preconditioned solver is compared with a conventional line Gauss-Seidel relaxation (LGSR) solver. Overall speed-up factors of 28 (in terms of global time-steps required to converge to a steady-state solution) and 20 (in terms of total CPU time on one processor of a CRAY-YMP) are found in favor of the new preconditioned solver, when compared with the LGSR solver.

  13. 14 CFR 23.253 - High speed characteristics.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High speed characteristics. 23.253 Section... Requirements § 23.253 High speed characteristics. If a maximum operating speed VMO/MMO is established under § 23.1505(c), the following speed increase and recovery characteristics must be met: (a) Operating...

  14. Continuous QKD and high speed data encryption

    Science.gov (United States)

    Zbinden, Hugo; Walenta, Nino; Guinnard, Olivier; Houlmann, Raphael; Wen, Charles Lim Ci; Korzh, Boris; Lunghi, Tommaso; Gisin, Nicolas; Burg, Andreas; Constantin, Jeremy; Legré, Matthieu; Trinkler, Patrick; Caselunghe, Dario; Kulesza, Natalia; Trolliet, Gregory; Vannel, Fabien; Junod, Pascal; Auberson, Olivier; Graf, Yoan; Curchod, Gilles; Habegger, Gilles; Messerli, Etienne; Portmann, Christopher; Henzen, Luca; Keller, Christoph; Pendl, Christian; Mühlberghuber, Michael; Roth, Christoph; Felber, Norbert; Gürkaynak, Frank; Schöni, Daniel; Muheim, Beat

    2013-10-01

    We present the results of a Swiss project dedicated to the development of high speed quantum key distribution and data encryption. The QKD engine features fully automated key exchange, hardware key distillation based on finite key security analysis, efficient authentication and wavelength division multiplexing of the quantum and the classical channel and one-time pas encryption. The encryption device allows authenticated symmetric key encryption (e.g AES) at rates of up to 100 Gb/s. A new quantum key can uploaded up to 1000 times second from the QKD engine.

  15. High speed UNIBUS-VME interface

    International Nuclear Information System (INIS)

    Olmos, P.

    1987-01-01

    An interface between VME an the UNIBUS of PDP or VAX computer is presented. The system supports high speed parallel communication (up to 1MB/S) and is composed of two modules. One of these is a commercial DR11M board which performs DMA transfers between UNIBUS and the external word. The other is a VME module specifically developed for this application. The interface has been tested under VMS operating system in VAX and VALET-PLUS system for the VME Bus. We describe in detail the VME module and its connection with the DR11M. Software, both in WMS and VALET, is also described. (Author) 7 refs

  16. A hierarchy for modeling high speed propulsion systems

    Science.gov (United States)

    Hartley, Tom T.; Deabreu, Alex

    1991-01-01

    General research efforts on reduced order propulsion models for control systems design are overviewed. Methods for modeling high speed propulsion systems are discussed including internal flow propulsion systems that do not contain rotating machinery such as inlets, ramjets, and scramjets. The discussion is separated into four sections: (1) computational fluid dynamics model for the entire nonlinear system or high order nonlinear models; (2) high order linearized model derived from fundamental physics; (3) low order linear models obtained from other high order models; and (4) low order nonlinear models. Included are special considerations on any relevant control system designs. The methods discussed are for the quasi-one dimensional Euler equations of gasdynamic flow. The essential nonlinear features represented are large amplitude nonlinear waves, moving normal shocks, hammershocks, subsonic combustion via heat addition, temperature dependent gases, detonation, and thermal choking.

  17. A Low Speed BIST Framework for High Speed Circuit Testing

    NARCIS (Netherlands)

    Speek, H.; Kerkhoff, Hans G.; Shashaani, M.; Sachdev, M.

    2000-01-01

    Testing of high performance integrated circuits is becoming increasingly a challenging task owing to high clock frequencies. Often testers are not able to test such devices due to their limited high frequency capabilities. In this article we outline a design-for-test methodology such that high

  18. Measurement of bubble velocity in an air/water flow through a narrow gap by using high-speed cinematography; Ermittlung der Blasengeschwindigkeit einer Luft/Wasser-Spaltstroemung mit Hilfe der Hochgeschwindigkeitskinematographie

    Energy Technology Data Exchange (ETDEWEB)

    Koerner, S.; Friedel, L. [Technische Univ. Hamburg-Harburg, Hamburg (Germany). Arbeitsbereich Stroemungsmechanik

    1998-05-01

    For the prediction of the establishing two-phase massflow for a given pressure difference across a narrow rectangular gap, beside others, the knowledge of the change of state of the gas phase and the fluiddynamic non-equilibrium in form of the slip velocity between the phases is needed. For an air/water bubbly flow it turned out by using high-speed cinematography that apart from the quick pressure decrease during the rapid acceleration at the gap inlet no significant difference between the measured and the predicted bubble size changes assuming an isothermal change of state of the air bubbles could be detected. The measured mean bubble velocities do not considerably deviate from the values calculated on the basis of a homogeneous flow. (orig.) [Deutsch] Zur Vorhersage des sich bei gegebener Druckdifferenz einstellenden Massenstroms eines Zweiphasengemischs durch enge Spalte ist neben der Zustandsaenderung der Gasphase waehrend der Druckabsenkung u.a. auch die Kenntnis des sich dabei einstellenden fluiddynamischen Ungleichgewichts in Form einer Relativgeschwindigkeit zwischen den Phasen von Bedeutung. Diese beiden Einfluesse wurden mit Hilfe der Hochgeschwindigkeitskinematographie fuer eine Wasser/Luft-Blasenstroemung untersucht. Abgesehen von der raschen Druckabsenkung aufgrund der ploetzlichen Querschnittsverengung im Spalteintritt treten keine nennenswerten Unterschiede zwischen den experimentell ermittelten und den unter der Annahme einer isothermen Zustandsaenderungen berechneten Volumenaenderung verschiedengrosser Blasen auf. Die mittlere Geschwindigkeit der Blasen unterscheidet sich dabei nicht wesentlich von der unter der Annahme einer homogenen Stroemung berechneten. (orig.)

  19. Numerical study on wake characteristics of high-speed trains

    Science.gov (United States)

    Yao, Shuan-Bao; Sun, Zhen-Xu; Guo, Di-Long; Chen, Da-Wei; Yang, Guo-Wei

    2013-12-01

    Intensive turbulence exists in the wakes of high speed trains, and the aerodynamic performance of the trailing car could deteriorate rapidly due to complicated features of the vortices in the wake zone. As a result, the safety and amenity of high speed trains would face a great challenge. This paper considers mainly the mechanism of vortex formation and evolution in the train flow field. A real CRH2 model is studied, with a leading car, a middle car and a trailing car included. Different running speeds and cross wind conditions are considered, and the approaches of unsteady Reynold-averaged Navier-Stokes (URANS) and detached eddy simulation (DES) are utilized, respectively. Results reveal that DES has better capability of capturing small eddies compared to URANS. However, for large eddies, the effects of two approaches are almost the same. In conditions without cross winds, two large vortex streets stretch from the train nose and interact strongly with each other in the wake zone. With the reinforcement of the ground, a complicated wake vortex system generates and becomes strengthened as the running speed increases. However, the locations of flow separations on the train surface and the separation mechanism keep unchanged. In conditions with cross winds, three large vortices develop along the leeward side of the train, among which the weakest one has no obvious influence on the wake flow while the other two stretch to the tail of the train and combine with the helical vortices in the train wake. Thus, optimization of the aerodynamic performance of the trailing car should be aiming at reducing the intensity of the wake vortex system.

  20. Predicting Free Flow Speed and Crash Risk of Bicycle Traffic Flow Using Artificial Neural Network Models

    Directory of Open Access Journals (Sweden)

    Cheng Xu

    2015-01-01

    Full Text Available Free flow speed is a fundamental measure of traffic performance and has been found to affect the severity of crash risk. However, the previous studies lack analysis and modelling of impact factors on bicycles’ free flow speed. The main focus of this study is to develop multilayer back propagation artificial neural network (BPANN models for the prediction of free flow speed and crash risk on the separated bicycle path. Four different models with considering different combinations of input variables (e.g., path width, traffic condition, bicycle type, and cyclists’ characteristics were developed. 459 field data samples were collected from eleven bicycle paths in Hangzhou, China, and 70% of total samples were used for training, 15% for validation, and 15% for testing. The results show that considering the input variables of bicycle types and characteristics of cyclists will effectively improve the accuracy of the prediction models. Meanwhile, the parameters of bicycle types have more significant effect on predicting free flow speed of bicycle compared to those of cyclists’ characteristics. The findings could contribute for evaluation, planning, and management of bicycle safety.

  1. Partial Cavity Flows at High Reynolds Numbers

    Science.gov (United States)

    Makiharju, Simo; Elbing, Brian; Wiggins, Andrew; Dowling, David; Perlin, Marc; Ceccio, Steven

    2009-11-01

    Partial cavity flows created for friction drag reduction were examined on a large-scale. Partial cavities were investigated at Reynolds numbers up to 120 million, and stable cavities with frictional drag reduction of more than 95% were attained at optimal conditions. The model used was a 3 m wide and 12 m long flat plate with a plenum on the bottom. To create the partial cavity, air was injected at the base of an 18 cm backwards-facing step 2.1 m from the leading edge. The geometry at the cavity closure was varied for different flow speeds to optimize the closure of the cavity. Cavity gas flux, thickness, frictional loads, and cavity pressures were measured over a range of flow speeds and air injection fluxes. High-speed video was used extensively to investigate the unsteady three dimensional cavity closure, the overall cavity shape and oscillations.

  2. 14 CFR 25.253 - High-speed characteristics.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-speed characteristics. 25.253 Section...-speed characteristics. (a) Speed increase and recovery characteristics. The following speed increase and recovery characteristics must be met: (1) Operating conditions and characteristics likely to cause...

  3. Florida intercity high speed rail passenger service

    Energy Technology Data Exchange (ETDEWEB)

    Najafi, F.T.; Watford, S.; Moore, G.; Des, A. [Florida Univ., Gainesville, FL (United States). Dept. of Civil Engineering

    1997-10-01

    Plans for a new high-speed rail (HSR) transportation system in Florida were reviewed. HSR is believed to be the least expensive, most energy-efficient and least environmentally harmful alternative to air and highway travel. The system in Florida will be used as a case study to determine its overall impact on the environment, people and economy. The 300-plus mile system will move travelers at speeds of over 200 mph between Miami, Orlando, and Tampa. The study will identify the impacts of a HSR system on existing transportation networks, environment, energy, growth and growth distribution, safety, economy, travel time, and tourism. Transportation problems and the innovative mechanisms needed to realize the joint public and private venture approach to planning, locating, permitting, managing, financing, constructing and maintaining an inter-regional HSR line for the state were studied. The all-electric train would greatly help the environment in two ways: (1) zero emissions from the train itself, and (2) the reduction of trips by automobile and aircraft would reduce the amount of fuel and energy being used. 4 refs., 1 fig.

  4. High-Speed RaPToRS

    Science.gov (United States)

    Henchen, Robert; Esham, Benjamin; Becker, William; Pogozelski, Edward; Padalino, Stephen; Sangster, Thomas; Glebov, Vladimir

    2008-11-01

    The High-Speed Rapid Pneumatic Transport of Radioactive Samples (HS-RaPToRS) system, designed to quickly and safely move radioactive materials, was assembled and tested at the Mercury facility of the Naval Research Laboratory (NRL) in Washington D.C. A sample, which is placed inside a four-inch-diameter carrier, is activated before being transported through a PVC tube via airflow. The carrier travels from the reaction chamber to the end station where it pneumatically brakes prior to the gate. A magnetic latch releases the gate when the carrier arrives and comes to rest. The airflow, optical carrier-monitoring devices, and end gate are controlled manually or automatically with LabView software. The installation and testing of the RaPToRS system at NRL was successfully completed with transport times of less than 3 seconds. The speed of the carrier averaged 16 m/s. Prospective facilities for similar systems include the Laboratory for Laser Energetics and the National Ignition Facility.

  5. Using a High-Speed Camera to Measure the Speed of Sound

    Science.gov (United States)

    Hack, William Nathan; Baird, William H.

    2012-01-01

    The speed of sound is a physical property that can be measured easily in the lab. However, finding an inexpensive and intuitive way for students to determine this speed has been more involved. The introduction of affordable consumer-grade high-speed cameras (such as the Exilim EX-FC100) makes conceptually simple experiments feasible. Since the…

  6. High speed operation of permanent magnet machines

    Science.gov (United States)

    El-Refaie, Ayman M.

    This work proposes methods to extend the high-speed operating capabilities of both the interior PM (IPM) and surface PM (SPM) machines. For interior PM machines, this research has developed and presented the first thorough analysis of how a new bi-state magnetic material can be usefully applied to the design of IPM machines. Key elements of this contribution include identifying how the unique properties of the bi-state magnetic material can be applied most effectively in the rotor design of an IPM machine by "unmagnetizing" the magnet cavity center posts rather than the outer bridges. The importance of elevated rotor speed in making the best use of the bi-state magnetic material while recognizing its limitations has been identified. For surface PM machines, this research has provided, for the first time, a clear explanation of how fractional-slot concentrated windings can be applied to SPM machines in order to achieve the necessary conditions for optimal flux weakening. A closed-form analytical procedure for analyzing SPM machines designed with concentrated windings has been developed. Guidelines for designing SPM machines using concentrated windings in order to achieve optimum flux weakening are provided. Analytical and numerical finite element analysis (FEA) results have provided promising evidence of the scalability of the concentrated winding technique with respect to the number of poles, machine aspect ratio, and output power rating. Useful comparisons between the predicted performance characteristics of SPM machines equipped with concentrated windings and both SPM and IPM machines designed with distributed windings are included. Analytical techniques have been used to evaluate the impact of the high pole number on various converter performance metrics. Both analytical techniques and FEA have been used for evaluating the eddy-current losses in the surface magnets due to the stator winding subharmonics. Techniques for reducing these losses have been

  7. High Speed Magnetostrictive MEMS Actuated Mirror Deflectors, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The main goal of this proposal is to develop high speed magnetostrictive and MEMS actuators for rapidly deflecting or deforming mirrors. High speed, light-weight,...

  8. High-speed and intercity passenger rail testing strategy.

    Science.gov (United States)

    2013-05-01

    This high-speed and intercity passenger rail (HSIPR) testing strategy addresses the requirements for testing of high-speed train sets and technology before introduction to the North American railroad system. The report documents the results of a surv...

  9. A high current, high speed pulser using avalanche transistors

    International Nuclear Information System (INIS)

    Hosono, Yoneichi; Hasegawa, Ken-ichi

    1985-01-01

    A high current, high speed pulser for the beam pulsing of a linear accelerator is described. It uses seven avalanche transistors in cascade. Design of a trigger circuit to obtain fast rise time is discussed. The characteristics of the pulser are : (a) Rise time = 0.9 ns (FWHM) and (d) Life time asymptotically equals 2000 -- 3000 hr (at 50 Hz). (author)

  10. High-speed cineradiographies acquisition and processing

    International Nuclear Information System (INIS)

    Kahn, E.; Nourrissat, Yves; Viguier, Philippe

    A high-speed cineradiography installation provides dimensional informations recorded either on a film, or on a magnetic tape. In the event of the film, the imperfection of our visual sense leads us to look for a method of measurement which allows us to extract the information from a noisy image; the association of an optical flying spot scanner with a computer is adapted to this use and allows us, for instance, to determine the inside and outside diameters of a sphere during its implosion. On the other hand, the radiographic recording on magnetic tape is processed, after numerisation by the computer, in the same way as the numeric tape generated after the optical scanner. We compare the results achieved by the two recording methods [fr

  11. Direct numerical simulation of laminar-turbulent flow over a flat plate at hypersonic flow speeds

    Science.gov (United States)

    Egorov, I. V.; Novikov, A. V.

    2016-06-01

    A method for direct numerical simulation of a laminar-turbulent flow around bodies at hypersonic flow speeds is proposed. The simulation is performed by solving the full three-dimensional unsteady Navier-Stokes equations. The method of calculation is oriented to application of supercomputers and is based on implicit monotonic approximation schemes and a modified Newton-Raphson method for solving nonlinear difference equations. By this method, the development of three-dimensional perturbations in the boundary layer over a flat plate and in a near-wall flow in a compression corner is studied at the Mach numbers of the free-stream of M = 5.37. In addition to pulsation characteristic, distributions of the mean coefficients of the viscous flow in the transient section of the streamlined surface are obtained, which enables one to determine the beginning of the laminar-turbulent transition and estimate the characteristics of the turbulent flow in the boundary layer.

  12. Development and numerical analysis of low specific speed mixed-flow pump

    International Nuclear Information System (INIS)

    Li, H F; Huo, Y W; Pan, Z B; Zhou, W C; He, M H

    2012-01-01

    With the development of the city, the market of the mixed flow pump with large flux and high head is prospect. The KSB Shanghai Pump Co., LTD decided to develop low speed specific speed mixed flow pump to meet the market requirements. Based on the centrifugal pump and axial flow pump model, aiming at the characteristics of large flux and high head, a new type of guide vane mixed flow pump was designed. The computational fluid dynamics method was adopted to analyze the internal flow of the new type model and predict its performances. The time-averaged Navier-Stokes equations were closed by SST k-ω turbulent model to adapt internal flow of guide vane with larger curvatures. The multi-reference frame(MRF) method was used to deal with the coupling of rotating impeller and static guide vane, and the SIMPLEC method was adopted to achieve the coupling solution of velocity and pressure. The computational results shows that there is great flow impact on the head of vanes at different working conditions, and there is great flow separation at the tailing of the guide vanes at different working conditions, and all will affect the performance of pump. Based on the computational results, optimizations were carried out to decrease the impact on the head of vanes and flow separation at the tailing of the guide vanes. The optimized model was simulated and its performance was predicted. The computational results show that the impact on the head of vanes and the separation at the tailing of the guide vanes disappeared. The high efficiency of the optimized pump is wide, and it fit the original design destination. The newly designed mixed flow pump is now in modeling and its experimental performance will be getting soon.

  13. Development and numerical analysis of low specific speed mixed-flow pump

    Science.gov (United States)

    Li, H. F.; Huo, Y. W.; Pan, Z. B.; Zhou, W. C.; He, M. H.

    2012-11-01

    With the development of the city, the market of the mixed flow pump with large flux and high head is prospect. The KSB Shanghai Pump Co., LTD decided to develop low speed specific speed mixed flow pump to meet the market requirements. Based on the centrifugal pump and axial flow pump model, aiming at the characteristics of large flux and high head, a new type of guide vane mixed flow pump was designed. The computational fluid dynamics method was adopted to analyze the internal flow of the new type model and predict its performances. The time-averaged Navier-Stokes equations were closed by SST k-ω turbulent model to adapt internal flow of guide vane with larger curvatures. The multi-reference frame(MRF) method was used to deal with the coupling of rotating impeller and static guide vane, and the SIMPLEC method was adopted to achieve the coupling solution of velocity and pressure. The computational results shows that there is great flow impact on the head of vanes at different working conditions, and there is great flow separation at the tailing of the guide vanes at different working conditions, and all will affect the performance of pump. Based on the computational results, optimizations were carried out to decrease the impact on the head of vanes and flow separation at the tailing of the guide vanes. The optimized model was simulated and its performance was predicted. The computational results show that the impact on the head of vanes and the separation at the tailing of the guide vanes disappeared. The high efficiency of the optimized pump is wide, and it fit the original design destination. The newly designed mixed flow pump is now in modeling and its experimental performance will be getting soon.

  14. High Speed/ Low Effluent Process for Ethanol

    Energy Technology Data Exchange (ETDEWEB)

    M. Clark Dale

    2006-10-30

    n this project, BPI demonstrated a new ethanol fermentation technology, termed the High Speed/ Low Effluent (HS/LE) process on both lab and large pilot scale as it would apply to wet mill and/or dry mill corn ethanol production. The HS/LE process allows very rapid fermentations, with 18 to 22% sugar syrups converted to 9 to 11% ethanol ‘beers’ in 6 to 12 hours using either a ‘consecutive batch’ or ‘continuous cascade’ implementation. This represents a 5 to 8X increase in fermentation speeds over conventional 72 hour batch fermentations which are the norm in the fuel ethanol industry today. The ‘consecutive batch’ technology was demonstrated on a large pilot scale (4,800 L) in a dry mill corn ethanol plant near Cedar Rapids, IA (Xethanol Biofuels). The pilot demonstrated that 12 hour fermentations can be accomplished on an industrial scale in a non-sterile industrial environment. Other objectives met in this project included development of a Low Energy (LE) Distillation process which reduces the energy requirements for distillation from about 14,000 BTU/gal steam ($0.126/gal with natural gas @ $9.00 MCF) to as low as 0.40 KW/gal electrical requirements ($0.022/gal with electricity @ $0.055/KWH). BPI also worked on the development of processes that would allow application of the HS/LE fermentation process to dry mill ethanol plants. A High-Value Corn ethanol plant concept was developed to produce 1) corn germ/oil, 2) corn bran, 3) ethanol, 4) zein protein, and 5) nutritional protein, giving multiple higher value products from the incoming corn stream.

  15. Numerical Simulation of 3D Solid-Liquid Turbulent Flow in a Low Specific Speed Centrifugal Pump: Flow Field Analysis

    Directory of Open Access Journals (Sweden)

    Baocheng Shi

    2014-06-01

    Full Text Available For numerically simulating 3D solid-liquid turbulent flow in low specific speed centrifugal pumps, the iteration convergence problem caused by complex internal structure and high rotational speed of pump is always a problem for numeral simulation researchers. To solve this problem, the combination of three measures of dynamic underrelaxation factor adjustment, step method, and rotational velocity control means according to residual curves trends of operating parameters was used to improve the numerical convergence. Numeral simulation of 3D turbulent flow in a low specific speed solid-liquid centrifugal pump was performed, and the results showed that the improved solution strategy is greatly helpful to the numerical convergence. Moreover, the 3D turbulent flow fields in pumps have been simulated for the bottom ash-particles with the volume fraction of 10%, 20%, and 30% at the same particle diameter of 0.1 mm. The two-phase calculation results are compared with those of single-phase clean water flow. The calculated results gave the main region of the abrasion of the impeller and volute casing and improve the hydraulic design of the impeller in order to decrease the abrasion and increase the service life of the pump.

  16. Flow speed measurement using two-point collective light scattering

    International Nuclear Information System (INIS)

    Heinemeier, N.P.

    1998-09-01

    Measurements of turbulence in plasmas and fluids using the technique of collective light scattering have always been plagued by very poor spatial resolution. In 1994, a novel two-point collective light scattering system for the measurement of transport in a fusion plasma was proposed. This diagnostic method was design for a great improvement of the spatial resolution, without sacrificing accuracy in the velocity measurement. The system was installed at the W7-AS steallartor in Garching, Germany, in 1996, and has been operating since. This master thesis is an investigation of the possible application of this new method to the measurement of flow speeds in normal fluids, in particular air, although the results presented in this work have significance for the plasma measurements as well. The main goal of the project was the experimental verification of previous theoretical predictions. However, the theoretical considerations presented in the thesis show that the method can only be hoped to work for flows that are almost laminar and shearless, which makes it of very small practical interest. Furthermore, this result also implies that the diagnostic at W7-AS cannot be expected to give the results originally hoped for. (au)

  17. Flow speed measurement using two-point collective light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Heinemeier, N.P

    1998-09-01

    Measurements of turbulence in plasmas and fluids using the technique of collective light scattering have always been plagued by very poor spatial resolution. In 1994, a novel two-point collective light scattering system for the measurement of transport in a fusion plasma was proposed. This diagnostic method was design for a great improvement of the spatial resolution, without sacrificing accuracy in the velocity measurement. The system was installed at the W7-AS steallartor in Garching, Germany, in 1996, and has been operating since. This master thesis is an investigation of the possible application of this new method to the measurement of flow speeds in normal fluids, in particular air, although the results presented in this work have significance for the plasma measurements as well. The main goal of the project was the experimental verification of previous theoretical predictions. However, the theoretical considerations presented in the thesis show that the method can only be hoped to work for flows that are almost laminar and shearless, which makes it of very small practical interest. Furthermore, this result also implies that the diagnostic at W7-AS cannot be expected to give the results originally hoped for. (au) 1 tab., 51 ills., 29 refs.

  18. High-speed railways in Japan

    International Nuclear Information System (INIS)

    Kyotani, Y.

    1974-01-01

    This paper reviews the development of conventional railways in Japan, leading up to the Shinkansen line, which at present runs at speeds up to 210km/h, and will in the future be speeded up to 260km/h. It then goes on to review the development of a superconductive, magnetically levitated train, which will constitute the next generation of railways, running at speeds of up to 500km/h. (author)

  19. the factors that affect the free flow speed on an arterial in ilorin, nigeria

    African Journals Online (AJOL)

    user

    lower average free flow speed of commercial saloon cars on wet pavement than on dry pavement, with 12% percentage ... average space mean speed in a low volume traffic stream when ..... travel way width and number of traffic control units.

  20. Inductive flow meter for measuring the speed of flow and gas volume contained in a flow of liquid metal

    International Nuclear Information System (INIS)

    Mueller, S.

    1980-01-01

    The speed of flow of the sodium is measured in two closely adjacent flow crossections using pairs of electrodes in the field of two disc-shaped permanent magnets made of AlNiCo 450, by means of measurements of running time of speed fluctuations. The result of the measurement is independent of the temperature of the sensor and the temperature of the sodium. The same arrangement makes it possible to determine the proportion by volume of the fission gas in sodium with a limiting freequency of several kHz. (DG) [de

  1. High-speed Stochastic Fatigue Testing

    DEFF Research Database (Denmark)

    Brincker, Rune; Sørensen, John Dalsgaard

    1990-01-01

    Good stochastic fatigue tests are difficult to perform. One of the major reasons is that ordinary servohydraulic loading systems realize the prescribed load history accurately at very low testing speeds only. If the speeds used for constant amplitude testing are applied to stochastic fatigue...

  2. Application of high speed photography for high current vacuum arcs

    NARCIS (Netherlands)

    Damstra, G.C.; Merck, W.F.H.; Vossen, J.W.G.L.; Janssen, M.F.P.; Bouwmeester, C.E.

    1998-01-01

    A high speed image detection system for 106 frames per second or 107 streaks per second has been developed for the testing of vacuum circuit breakers, using 10×16 optical fibres for light transfer to 160 fast photo diodes. The output of these diodes is multiplexed, AD converted in a 4 bit

  3. Hydrodynamic characteristics of high speed settling clarifiers by radiotracer method

    International Nuclear Information System (INIS)

    Griffith Martinez, J.; Flores Juan, P.; Cuesta Borges, J.; Damera Martinez, A.; Ramos Espinosa, K. A

    2005-01-01

    Results achieved in the evaluation of two high-speed settling cane juice Clarifiers, one denominated ICINAZ The Express and the other one with Low Residence Time (BTR), both located at the sugar factory Orlando Gonzalez employing the well established radiotracer method (Tc-99m) are presented. Several trials performed at the two Clarifiers demonstrated that the one identified as BTR was capable to assimilate the whole flow capacity of the factory with adequate characteristic of the pattern flux and residence time in the environment of 1 hour. In the other side, ICINAZ The Express Clarifier could only work at relative low flow capacity of the factory with residence time closely to the two hours and achieving occasionally a pattern flux seriously affected by fluctuations in the milling process. The radiotracer method was able to detect certain differences between the two clear juice outlet of the BTR Clarifier, probably due some problems in the construction of this equipment

  4. Canadian high speed magnetically levitated vehicle system

    Energy Technology Data Exchange (ETDEWEB)

    Atherton, D L [Queen' s Univ., Kingston, Ont.; Belanger, P R; Burke, P E; Dawson, G E; Eastham, A R; Hayes, W F; Ooi, B T; Silvester, P; Slemon, G R

    1978-04-01

    A technically feasible high speed (400 to 480 km/h) guided ground transportation system, based on the use of the vehicle-borne superconducting magnets for electrodynamic suspension and guidance and for linear synchronous motor propulsion was defined as a future modal option for Canadian application. Analysis and design proposals were validated by large-scale tests on a rotating wheel facility and by modelling system components and their interactions. Thirty ton vehicles carrying 100 passengers operate over a flat-topped elevated guideway, which minimizes system down-time due to ice and snow accumulation and facilitates the design of turn-outs. A clearance of up to 15 cm is produced by the electrodynamic interaction between the vehicle-borne superconducting magnets and aluminum guideway strips. Propulsion and automatic system control is provided by the superconducting linear synchronous motor which operates at good efficiency (0.74) and high power factor (0.95). The vehicle is guided primarily by the interaction between the LSM field magnet array and flat null-flux loops overlying the stator windings in the guideway. The linear synchronous motor, electrodynamic suspension as well as levitation strip joints, parasitic LSM winding losses and limitations to the use of ferromagnetic guideway reinforcement were investigated experimentally on the test wheel facility. The use of a secondary suspension assures adequate dynamic stability, and good ride quality is achieved by optimized passive components with respect to lateral modes and by an actively controlled secondary suspension with respect to vertical motion.

  5. Material constraints on high-speed design

    Science.gov (United States)

    Bucur, Diana; Militaru, Nicolae

    2015-02-01

    Current high-speed circuit designs with signal rates up to 100Gbps and above are implying constraints for dielectric and conductive materials and their dependence of frequency, for component elements and for production processes. The purpose of this paper is to highlight through various simulation results the frequency dependence of specific parameters like insertion and return loss, eye diagrams, group delay that are part of signal integrity analyses type. In low-power environment designs become more complex as the operation frequency increases. The need for new materials with spatial uniformity for dielectric constant is a need for higher data rates circuits. The fiber weave effect (FWE) will be analyzed through the eye diagram results for various dielectric materials in a differential signaling scheme given the fact that the FWE is a phenomenon that affects randomly the performance of the circuit on balanced/differential transmission lines which are typically characterized through the above mentioned approaches. Crosstalk between traces is also of concern due to propagated signals that have tight rise and fall times or due to high density of the boards. Criteria should be considered to achieve maximum performance of the designed system requiring critical electronic properties.

  6. Simulations of High Speed Fragment Trajectories

    Science.gov (United States)

    Yeh, Peter; Attaway, Stephen; Arunajatesan, Srinivasan; Fisher, Travis

    2017-11-01

    Flying shrapnel from an explosion are capable of traveling at supersonic speeds and distances much farther than expected due to aerodynamic interactions. Predicting the trajectories and stable tumbling modes of arbitrary shaped fragments is a fundamental problem applicable to range safety calculations, damage assessment, and military technology. Traditional approaches rely on characterizing fragment flight using a single drag coefficient, which may be inaccurate for fragments with large aspect ratios. In our work we develop a procedure to simulate trajectories of arbitrary shaped fragments with higher fidelity using high performance computing. We employ a two-step approach in which the force and moment coefficients are first computed as a function of orientation using compressible computational fluid dynamics. The force and moment data are then input into a six-degree-of-freedom rigid body dynamics solver to integrate trajectories in time. Results of these high fidelity simulations allow us to further understand the flight dynamics and tumbling modes of a single fragment. Furthermore, we use these results to determine the validity and uncertainty of inexpensive methods such as the single drag coefficient model.

  7. High speed all-silicon optical modulator

    International Nuclear Information System (INIS)

    Marris-Morini, Delphine; Le Roux, Xavier; Pascal, Daniel; Vivien, Laurent; Cassan, Eric; Fedeli, Jean Marc; Damlencourt, Jean Francois; Bouville, David; Palomo, Jose; Laval, Suzanne

    2006-01-01

    Electrorefractive effect is experimentally demonstrated in an all-silicon optical structure. A highly doped Si P + layer is embedded in the intrinsic region of a PIN diode integrated in a SOI waveguide. Holes are confined at equilibrium around the P + layer. By applying a reverse bias to the diode, electrical field sweeps the carriers out of the active region. Free carrier concentration variations are responsible for local refractive index variations leading to an effective index variation of the waveguide optical mode and to an optical absorption variation. As a figure of merit, the product V π L π , determined from the measured effective index variation, is equal to 3.1 V cm. Furthermore, the device performances have theoretically been investigated. Estimations show that V π L π as small as 1 V cm are feasible using optimized structures. Response times lower than 2 ps are predicted, which gives the possibility to achieve very high-speed modulation. Furthermore, a temperature increases from 300 to 400 K does not change the index variation amplitude, and despite the carrier mobility reduction, response times are still lower than 2 ps

  8. AC-DC integrated load flow calculation for variable speed offshore wind farms

    DEFF Research Database (Denmark)

    Zhao, Menghua; Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    This paper proposes a sequential AC-DC integrated load flow algorithm for variable speed offshore wind farms. In this algorithm, the variable frequency and the control strategy of variable speed wind turbine systems are considered. In addition, the losses of wind turbine systems and the losses...... of converters are also integrated into the load flow algorithm. As a general algorithm, it can be applied to different types of wind farm configurations, and the load flow is related to the wind speed....

  9. High-Speed Data Recorder for Space, Geodesy, and Other High-Speed Recording Applications

    Science.gov (United States)

    Taveniku, Mikael

    2013-01-01

    A high-speed data recorder and replay equipment has been developed for reliable high-data-rate recording to disk media. It solves problems with slow or faulty disks, multiple disk insertions, high-altitude operation, reliable performance using COTS hardware, and long-term maintenance and upgrade path challenges. The current generation data recor - ders used within the VLBI community are aging, special-purpose machines that are both slow (do not meet today's requirements) and are very expensive to maintain and operate. Furthermore, they are not easily upgraded to take advantage of commercial technology development, and are not scalable to multiple 10s of Gbit/s data rates required by new applications. The innovation provides a softwaredefined, high-speed data recorder that is scalable with technology advances in the commercial space. It maximally utilizes current technologies without being locked to a particular hardware platform. The innovation also provides a cost-effective way of streaming large amounts of data from sensors to disk, enabling many applications to store raw sensor data and perform post and signal processing offline. This recording system will be applicable to many applications needing realworld, high-speed data collection, including electronic warfare, softwaredefined radar, signal history storage of multispectral sensors, development of autonomous vehicles, and more.

  10. Design of a high-speed electrochemical scanning tunneling microscope.

    Science.gov (United States)

    Yanson, Y I; Schenkel, F; Rost, M J

    2013-02-01

    In this paper, we present a bottom-up approach to designing and constructing a high-speed electrochemical scanning tunneling microscope (EC-STM). Using finite element analysis (FEA) calculations of the frequency response of the whole mechanical loop of the STM, we analyzed several geometries to find the most stable one that could facilitate fast scanning. To test the FEA results, we conducted measurements of the vibration amplitudes using a prototype STM setup. Based on the FEA analysis and the measurement results, we identified the potentially most disturbing vibration modes that could impair fast scanning. By modifying the design of some parts of the EC-STM, we reduced the amplitudes as well as increased the resonance frequencies of these modes. Additionally, we designed and constructed an electrochemical flow-cell that allows STM imaging in a flowing electrolyte, and built a bi-potentiostat to achieve electrochemical potential control during the measurements. Finally, we present STM images acquired during high-speed imaging in air as well as in an electrochemical environment using our newly-developed EC-STM.

  11. Modelling Free Flow Speed on Two-Lane Rural Highways in Bosnia and Herzegovina

    Directory of Open Access Journals (Sweden)

    Ivan Lovrić

    2014-04-01

    Full Text Available Free flow speed is used as a parameter in transportation planning and capacity analysis models, as well as speed-flow diagrams. Many of these models suggest estimating free flow speed according to measurements from similar highways, which is not a practical method for use in B&H. This paper first discusses problems with using these methodologies in conditions prevailing in B&H and then presents a free flow speed evaluation model developed from a comprehensive field survey conducted on nine homogeneous sections of state and regional roads.

  12. Free-flow speeds for representative road and terrain types

    CSIR Research Space (South Africa)

    Schutte, IC

    2009-06-02

    Full Text Available Speed plays an important role in the justification of road infrstructure projects. It affects both vehicle operating cost and travel time cost. If incorrecr values for speed are used in the economic analyses of transport projects, incorrect...

  13. High-Speed Interferometry Under Impacting Drops

    KAUST Repository

    Langley, Kenneth R.; Li, Erqiang; Thoroddsen, Sigurdur T

    2017-01-01

    Over the last decade the rapid advances in high-speed video technology, have opened up to study many multi-phase fluid phenomena, which tend to occur most rapidly on the smallest length-scales. One of these is the entrapment of a small bubble under a drop impacting onto a solid surface. Here we have gone from simply observing the presence of the bubble to detailed imaging of the formation of a lubricating air-disc under the drop center and its subsequent contraction into the bubble. Imaging the full shape-evolution of the air-disc has required μm and sub-μs space and time resolutions. Time-resolved 200 ns interferometry with monochromatic light, has allowed us to follow individual fringes to obtain absolute air-layer thicknesses, based on the eventual contact with the solid. We can follow the evolution of the dimple shape as well as the compression of the gas. The improved imaging has also revealed new levels of detail, like the nature of the first contact which produces a ring of micro-bubbles, highlighting the influence of nanometric surface roughness. Finally, for impacts of ultra-viscous drops we see gliding on ~100 nm thick rarified gas layers, followed by extreme wetting at numerous random spots.

  14. High-Speed Interferometry Under Impacting Drops

    KAUST Repository

    Langley, Kenneth R.

    2017-08-31

    Over the last decade the rapid advances in high-speed video technology, have opened up to study many multi-phase fluid phenomena, which tend to occur most rapidly on the smallest length-scales. One of these is the entrapment of a small bubble under a drop impacting onto a solid surface. Here we have gone from simply observing the presence of the bubble to detailed imaging of the formation of a lubricating air-disc under the drop center and its subsequent contraction into the bubble. Imaging the full shape-evolution of the air-disc has required μm and sub-μs space and time resolutions. Time-resolved 200 ns interferometry with monochromatic light, has allowed us to follow individual fringes to obtain absolute air-layer thicknesses, based on the eventual contact with the solid. We can follow the evolution of the dimple shape as well as the compression of the gas. The improved imaging has also revealed new levels of detail, like the nature of the first contact which produces a ring of micro-bubbles, highlighting the influence of nanometric surface roughness. Finally, for impacts of ultra-viscous drops we see gliding on ~100 nm thick rarified gas layers, followed by extreme wetting at numerous random spots.

  15. The high speed civil transport and NASA's High Speed Research (HSR) program

    Science.gov (United States)

    Shaw, Robert J.

    1994-01-01

    Ongoing studies being conducted not only in this country but in Europe and Asia suggest that a second generation supersonic transport, or High-Speed Civil Transport (HSCT), could become an important part of the 21st century international air transportation system. However, major environmental compatibility and economic viability issues must be resolved if the HSCT is to become a reality. This talk will overview the NASA High-Speed Research (HSR) program which is aimed at providing the U.S. industry with a technology base to allow them to consider launching an HSCT program early in the next century. The talk will also discuss some of the comparable activities going on within Europe and Japan.

  16. High Speed Dynamics in Brittle Materials

    Science.gov (United States)

    Hiermaier, Stefan

    2015-06-01

    Brittle Materials under High Speed and Shock loading provide a continuous challenge in experimental physics, analysis and numerical modelling, and consequently for engineering design. The dependence of damage and fracture processes on material-inherent length and time scales, the influence of defects, rate-dependent material properties and inertia effects on different scales make their understanding a true multi-scale problem. In addition, it is not uncommon that materials show a transition from ductile to brittle behavior when the loading rate is increased. A particular case is spallation, a brittle tensile failure induced by the interaction of stress waves leading to a sudden change from compressive to tensile loading states that can be invoked in various materials. This contribution highlights typical phenomena occurring when brittle materials are exposed to high loading rates in applications such as blast and impact on protective structures, or meteorite impact on geological materials. A short review on experimental methods that are used for dynamic characterization of brittle materials will be given. A close interaction of experimental analysis and numerical simulation has turned out to be very helpful in analyzing experimental results. For this purpose, adequate numerical methods are required. Cohesive zone models are one possible method for the analysis of brittle failure as long as some degree of tension is present. Their recent successful application for meso-mechanical simulations of concrete in Hopkinson-type spallation tests provides new insight into the dynamic failure process. Failure under compressive loading is a particular challenge for numerical simulations as it involves crushing of material which in turn influences stress states in other parts of a structure. On a continuum scale, it can be modeled using more or less complex plasticity models combined with failure surfaces, as will be demonstrated for ceramics. Models which take microstructural

  17. Implementation of High Speed Distributed Data Acquisition System

    Science.gov (United States)

    Raju, Anju P.; Sekhar, Ambika

    2012-09-01

    This paper introduces a high speed distributed data acquisition system based on a field programmable gate array (FPGA). The aim is to develop a "distributed" data acquisition interface. The development of instruments such as personal computers and engineering workstations based on "standard" platforms is the motivation behind this effort. Using standard platforms as the controlling unit allows independence in hardware from a particular vendor and hardware platform. The distributed approach also has advantages from a functional point of view: acquisition resources become available to multiple instruments; the acquisition front-end can be physically remote from the rest of the instrument. High speed data acquisition system transmits data faster to a remote computer system through Ethernet interface. The data is acquired through 16 analog input channels. The input data commands are multiplexed and digitized and then the data is stored in 1K buffer for each input channel. The main control unit in this design is the 16 bit processor implemented in the FPGA. This 16 bit processor is used to set up and initialize the data source and the Ethernet controller, as well as control the flow of data from the memory element to the NIC. Using this processor we can initialize and control the different configuration registers in the Ethernet controller in a easy manner. Then these data packets are sending to the remote PC through the Ethernet interface. The main advantages of the using FPGA as standard platform are its flexibility, low power consumption, short design duration, fast time to market, programmability and high density. The main advantages of using Ethernet controller AX88796 over others are its non PCI interface, the presence of embedded SRAM where transmit and reception buffers are located and high-performance SRAM-like interface. The paper introduces the implementation of the distributed data acquisition using FPGA by VHDL. The main advantages of this system are high

  18. Study of fish response using particle image velocimetry and high-speed, high-resolution imaging

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Richmond, M. C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mueller, R. P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gruensch, G. R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2004-10-01

    Fish swimming has fascinated both engineers and fish biologists for decades. Digital particle image velocimetry (DPIV) and high-speed, high-resolution digital imaging are recently developed analysis tools that can help engineers and biologists better understand how fish respond to turbulent environments. This report details studies to evaluate DPIV. The studies included a review of existing literature on DPIV, preliminary studies to test the feasibility of using DPIV conducted at our Flow Biology Laboratory in Richland, Washington September through December 2003, and applications of high-speed, high-resolution digital imaging with advanced motion analysis to investigations of fish injury mechanisms in turbulent shear flows and bead trajectories in laboratory physical models. Several conclusions were drawn based on these studies, which are summarized as recommendations for proposed research at the end of this report.

  19. Experimental Comparison of Speed : Fuel-flow and Speed-area Controls on a Turbojet Engine for Small Step Disturbances

    Science.gov (United States)

    Wenzel, L M; Hart, C E; Craig, R T

    1957-01-01

    Optimum proportional-plus-integral control settings for speed - fuel-flow control, determined by minimization of integral criteria, correlated well with analytically predicted optimum settings. Engine response data are given for a range of control settings around the optimum. An inherent nonlinearity in the speed-area loop necessitated the use of nonlinear controls. Response data for two such nonlinear control schemes are presented.

  20. Influence of speed and frequency towards the automotive turbocharger turbine performance under pulsating flow conditions

    International Nuclear Information System (INIS)

    Padzillah, M.H.; Rajoo, S.; Martinez-Botas, R.F.

    2014-01-01

    Highlights: • 3D CFD modeling of a turbocharger turbine with pulsating flow. • Characterization based on turbine speed and frequency. • Speed has higher influence on turbine performance compared to frequency. • Detailed localized flow behavior are shown for better understanding. - Abstract: The ever-increasing demand for low carbon applications in automotive industry has intensified the development of highly efficient engines and energy recovery devices. Even though there are significant developments in the alternative powertrains such as full electric, their full deployment is hindered by high costing and unattractive life-cycle energy and emission balance. Thus powertrain based on highly efficient internal combustion engines are still considered to be the mainstream for years to come. Traditionally, turbocharger has been an essential tool to boost the engine power, however in recent years it is seen as an enabling technology for engine downsizing. It is a well-known fact that a turbocharger turbine in an internal combustion engine operates in a highly pulsating exhaust flow. There are numerous studies looking into the complex interaction of the pulsating exhaust gas within the turbocharger turbine, however the phenomena is still not fully integrated into the design stage. Industry practice is still to design and match the turbine to an engine based on steady performance maps. The current work is undertaken with the mind to move one step closer towards fully integrating the pulsating flow performance into the turbocharger turbine design. This paper presents the development efforts and results from a full 3-D CFD model of a turbocharger turbine stage. The simulations were conducted at 30,000 rpm and 48,000 rpm (50% and 80% design speed respectively) for both 20 Hz and 80 Hz pulsating flow inlet conditions. Complete validation procedure using cold-flow experimental data is also described. The temporal and spatial resolutions of the incidence angle at the

  1. The effect of tip speed ratio on a vertical axis wind turbine at high Reynolds numbers

    Science.gov (United States)

    Parker, Colin M.; Leftwich, Megan C.

    2016-05-01

    This work visualizes the flow surrounding a scaled model vertical axis wind turbine at realistic operating conditions. The model closely matches geometric and dynamic properties—tip speed ratio and Reynolds number—of a full-size turbine. The flow is visualized using particle imaging velocimetry (PIV) in the midplane upstream, around, and after (up to 4 turbine diameters downstream) the turbine, as well as a vertical plane behind the turbine. Time-averaged results show an asymmetric wake behind the turbine, regardless of tip speed ratio, with a larger velocity deficit for a higher tip speed ratio. For the higher tip speed ratio, an area of averaged flow reversal is present with a maximum reverse flow of -0.04U_∞. Phase-averaged vorticity fields—achieved by syncing the PIV system with the rotation of the turbine—show distinct structures form from each turbine blade. There were distinct differences in results by tip speed ratios of 0.9, 1.3, and 2.2 of when in the cycle structures are shed into the wake—switching from two pairs to a single pair of vortices being shed—and how they convect into the wake—the middle tip speed ratio vortices convect downstream inside the wake, while the high tip speed ratio pair is shed into the shear layer of the wake. Finally, results show that the wake structure is much more sensitive to changes in tip speed ratio than to changes in Reynolds number.

  2. High-speed cinematography of gas-metal atomization

    Energy Technology Data Exchange (ETDEWEB)

    Ting, Jason [ALCOA Specialty Metals Division, 100 Technical Drive, Alcoa Center, PA 15069 (United States)]. E-mail: jason.ting@alcoa.com; Connor, Jeffery [Material Science Engineering Department, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Ridder, Stephen [Metallurgical Processing Group, NIST, 100 Bureau Dr. Stop 8556, Gaithersburg, MD 20899 (United States)

    2005-01-15

    A high-speed cinematographic footage of a 304L stainless steel gas atomization, recorded at the National Institute of Standard and Technology (NIST), was analyzed using a discrete Fourier transform (DFT) algorithm. The analysis showed the gas atomization process possesses two prominent frequency ranges of melt oscillation (pulsation). A low-frequency oscillation in the melt flow occurring between 5.41 and 123 Hz, with a dominant frequency at 9.93 Hz, was seen in the recirculation zone adjacent to the melt orifice. A high-frequency melt oscillation range was observed above 123 Hz, and was more prominent one melt-tip-diameter downstream in the melt atomization image than upstream near the melt tip. This high-frequency range may reflect the melt atomization frequency used to produce finely atomized powder. This range also included a prominent high frequency at 1273 Hz, which dominated in the image further away downstream from the melt tip. This discrete high-frequency oscillation is most probably caused by the aeroacoustic ''screech'' phenomenon, intrasound (<20 kHz), a result of the atomizing gas jets undergoing flow resonance. It is hypothesized that this discrete intrinsic aeroacoustic tone may enhance melt breakup in the atomization process with evidence of this fact in the melt images.

  3. High-speed cinematography of gas-metal atomization

    International Nuclear Information System (INIS)

    Ting, Jason; Connor, Jeffery; Ridder, Stephen

    2005-01-01

    A high-speed cinematographic footage of a 304L stainless steel gas atomization, recorded at the National Institute of Standard and Technology (NIST), was analyzed using a discrete Fourier transform (DFT) algorithm. The analysis showed the gas atomization process possesses two prominent frequency ranges of melt oscillation (pulsation). A low-frequency oscillation in the melt flow occurring between 5.41 and 123 Hz, with a dominant frequency at 9.93 Hz, was seen in the recirculation zone adjacent to the melt orifice. A high-frequency melt oscillation range was observed above 123 Hz, and was more prominent one melt-tip-diameter downstream in the melt atomization image than upstream near the melt tip. This high-frequency range may reflect the melt atomization frequency used to produce finely atomized powder. This range also included a prominent high frequency at 1273 Hz, which dominated in the image further away downstream from the melt tip. This discrete high-frequency oscillation is most probably caused by the aeroacoustic ''screech'' phenomenon, intrasound (<20 kHz), a result of the atomizing gas jets undergoing flow resonance. It is hypothesized that this discrete intrinsic aeroacoustic tone may enhance melt breakup in the atomization process with evidence of this fact in the melt images

  4. Estimation of Engine Intake Air Mass Flow using a generic Speed-Density method

    Directory of Open Access Journals (Sweden)

    Vojtíšek Michal

    2014-10-01

    Full Text Available Measurement of real driving emissions (RDE from internal combustion engines under real-world operation using portable, onboard monitoring systems (PEMS is becoming an increasingly important tool aiding the assessment of the effects of new fuels and technologies on environment and human health. The knowledge of exhaust flow is one of the prerequisites for successful RDE measurement with PEMS. One of the simplest approaches for estimating the exhaust flow from virtually any engine is its computation from the intake air flow, which is calculated from measured engine rpm and intake manifold charge pressure and temperature using a generic speed-density algorithm, applicable to most contemporary four-cycle engines. In this work, a generic speed-density algorithm was compared against several reference methods on representative European production engines - a gasoline port-injected automobile engine, two turbocharged diesel automobile engines, and a heavy-duty turbocharged diesel engine. The overall results suggest that the uncertainty of the generic speed-density method is on the order of 10% throughout most of the engine operating range, but increasing to tens of percent where high-volume exhaust gas recirculation is used. For non-EGR engines, such uncertainty is acceptable for many simpler and screening measurements, and may be, where desired, reduced by engine-specific calibration.

  5. High Speed impedance tomography for cardiac imaging

    International Nuclear Information System (INIS)

    Tehrani, J.N.; Jin, C.; Schaik, Andre

    2010-01-01

    Full text: Electrical Impedance Tomography (EIT) calculates the internal conductivity distribution within a body using electrical contact measurements. Previous investigation has shown that optimizing electrode placement can give better information about the stroke volume and better separation between the ventricles and atria than with the electrodes attached in the transverse plane. In our investigation we are developing fast three dimensional imaging of the heart (two planes of 16 electrodes) including internal electrodes in esophagus. The reconstruction speed in EIT is one of the main limitations for real time imaging when using a detailed three dimensional finite element mesh. For that reason we investigated new iterative algorithms for solving large scale LJ regularization. In this research we compare these algorithms on noise reliability and speed for 2D cardiac models. The four methods were as follows: (I) an interior point method for solving Ll-regularized least squares problems (Ll-LS); (2) total variation using a Lagrangian multiplier (TV AL3); (3) a two step iterative shrinkage/thresholding method (TWIST) for solving the Lo-regularized least squares problem; (4) The Least Absolute Shrinkage and Selection Operator (LASSO). In our investigation, using 1600 elements, we found all four algorithms provided an improvement over the best conventional EIT reconstruction method, Total Variation, in three important areas: robustness to noise, increased computational speed of at least 40 x and a visually apparent improvement in spatial resolution. Out of the four algorithms we found TWIST was the fastest with at least a 1 00 x speed increase. (author)

  6. Concept for high speed computer printer

    Science.gov (United States)

    Stephens, J. W.

    1970-01-01

    Printer uses Kerr cell as light shutter for controlling the print on photosensitive paper. Applied to output data transfer, the information transfer rate of graphic computer printers could be increased to speeds approaching the data transfer rate of computer central processors /5000 to 10,000 lines per minute/.

  7. Chicago-St. Louis high speed rail plan

    International Nuclear Information System (INIS)

    Stead, M.E.

    1994-01-01

    The Illinois Department of Transportation (IDOT), in cooperation with Amtrak, undertook the Chicago-St. Louis High Speed Rail Financial and Implementation Plan study in order to develop a realistic and achievable blueprint for implementation of high speed rail in the Chicago-St. Louis corridor. This report presents a summary of the Price Waterhouse Project Team's analysis and the Financial and Implementation Plan for implementing high speed rail service in the Chicago-St. Louis corridor

  8. 33 CFR 84.24 - High-speed craft.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false High-speed craft. 84.24 Section... RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.24 High-speed craft. (a) The masthead light of high-speed craft with a length to breadth ratio of less than 3.0 may be placed at a...

  9. A Historical Review of High Speed Metal Forming

    OpenAIRE

    Zittel, G.

    2010-01-01

    This paper will present a Historical Review of High Speed Metal Forming beginning with the first thought of forming metal by using an electromagnetic impulse to today, whereby High Speed Metal Forming is an accepted production process. Although this paper will briefly cover the basic physics of the process, it will not dwell on it. It will rather show how the industrial acceptance of High Speed Metal Forming is tightly connected to the knowledge acquired from many applications studies. These ...

  10. Chicago-St. Louis high speed rail plan

    Energy Technology Data Exchange (ETDEWEB)

    Stead, M.E.

    1994-12-31

    The Illinois Department of Transportation (IDOT), in cooperation with Amtrak, undertook the Chicago-St. Louis High Speed Rail Financial and Implementation Plan study in order to develop a realistic and achievable blueprint for implementation of high speed rail in the Chicago-St. Louis corridor. This report presents a summary of the Price Waterhouse Project Team`s analysis and the Financial and Implementation Plan for implementing high speed rail service in the Chicago-St. Louis corridor.

  11. Modeling of speed distribution for mixed bicycle traffic flow

    Directory of Open Access Journals (Sweden)

    Cheng Xu

    2015-11-01

    Full Text Available Speed is a fundamental measure of traffic performance for highway systems. There were lots of results for the speed characteristics of motorized vehicles. In this article, we studied the speed distribution for mixed bicycle traffic which was ignored in the past. Field speed data were collected from Hangzhou, China, under different survey sites, traffic conditions, and percentages of electric bicycle. The statistics results of field data show that the total mean speed of electric bicycles is 17.09 km/h, 3.63 km/h faster and 27.0% higher than that of regular bicycles. Normal, log-normal, gamma, and Weibull distribution models were used for testing speed data. The results of goodness-of-fit hypothesis tests imply that the log-normal and Weibull model can fit the field data very well. Then, the relationships between mean speed and electric bicycle proportions were proposed using linear regression models, and the mean speed for purely electric bicycles or regular bicycles can be obtained. The findings of this article will provide effective help for the safety and traffic management of mixed bicycle traffic.

  12. Time optimal paths for high speed maneuvering

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Lenhart, S.M.

    1993-01-01

    Recent theoretical results have completely solved the problem of determining the minimum length path for a vehicle with a minimum turning radius moving from an initial configuration to a final configuration. Time optimal paths for a constant speed vehicle are a subset of the minimum length paths. This paper uses the Pontryagin maximum principle to find time optimal paths for a constant speed vehicle. The time optimal paths consist of sequences of axes of circles and straight lines. The maximum principle introduces concepts (dual variables, bang-bang solutions, singular solutions, and transversality conditions) that provide important insight into the nature of the time optimal paths. We explore the properties of the optimal paths and present some experimental results for a mobile robot following an optimal path.

  13. Application of polarization in high speed, high contrast inspection

    Science.gov (United States)

    Novak, Matthew J.

    2017-08-01

    Industrial optical inspection often requires high speed and high throughput of materials. Engineers use a variety of techniques to handle these inspection needs. Some examples include line scan cameras, high speed multi-spectral and laser-based systems. High-volume manufacturing presents different challenges for inspection engineers. For example, manufacturers produce some components in quantities of millions per month, per week or even per day. Quality control of so many parts requires creativity to achieve the measurement needs. At times, traditional vision systems lack the contrast to provide the data required. In this paper, we show how dynamic polarization imaging captures high contrast images. These images are useful for engineers to perform inspection tasks in some cases where optical contrast is low. We will cover basic theory of polarization. We show how to exploit polarization as a contrast enhancement technique. We also show results of modeling for a polarization inspection application. Specifically, we explore polarization techniques for inspection of adhesives on glass.

  14. Hydrodynamic characteristics of high speed settling clarifiers by radiotracer method

    International Nuclear Information System (INIS)

    Griffith Martinez, Jose; Damera Martinez, A.; Ramos Espinosa, K.

    2003-01-01

    Results achieved in the evaluation of two high-speed settling cane juice Clarifiers, one denominated ICINAZ The Express and the other one a modified SRI, both located at the sugar factory Orlando Gonzalez employing the well established radiotracer method (Tc-99m) are presented Several trials performed simultaneously at the two Clarifiers demonstrated that the modified SRI was capable to assimilate the whole flow capacity of the factory with adequate characteristic of the pattern flux and residence time in the environment of 1 hour. In the other side, ICINAZ The Express Clarifier could only work at relative low flow capacity of the factory with residence time closely to the two hours and achieving occasionally a pattern flux seriously affected by fluctuations in the milling process. The non-availability of a flow meter did not allow to extract more information related to some pattern flux anomalies, nevertheless, the radiotracer method was able to detect certain differences between the two clear juice outlet of the modified SRI Clarifier, probably due some problems in the construction of this equipment. This fact so as other goals achieved in this work, show once more the potentiality of the radiotracer method for this type of study related to the hydrodynamic characteristics of industrial facilities. (Author)

  15. A matrix-free implicit treatment for all speed flows on unstructured grids

    International Nuclear Information System (INIS)

    Kloczko, Th.

    2006-03-01

    The aim of this research work is the development of an efficient implicit scheme for computing compressible and low-speed flows on unstructured meshes. The first part is devoted to the review and analysis of some standard block-implicit treatments for the two-dimensional Euler and Navier-Stokes equations with a view to identify the best candidate for a fair comparison with the matrix-free treatment. The second part forms the main original contribution of this research work. It describes and analyses a matrix-free treatment that can be applied to any type of flow (inviscid/viscous, low Mach/highly compressible, steady/unsteady). The third part deals with the implementation of this treatment within the CAST3M code, and the demonstration of its advantages over existing techniques for computing applications of interest for the CEA: low-Mach number steady and unsteady flows in a Tee junction for example

  16. Application of high-speed photography to hydrodynamic instability research

    International Nuclear Information System (INIS)

    Chang Lihua; Li Zuoyou; Xiao Zhengfei; Zou Liyong; Liu Jinhong; Xiong Xueshi

    2012-01-01

    High-speed photography is used to study the Rayleigh-Taylor instability of air-water interface driven by high- pressure exploding gas. Clear images illustrating the instability are obtained, along with the air bubble peak speed and turbulent mixing speed. The RM (Richtmyer-Meshkov) instability of air/SF 6 interface driven by shock wave is also researched by using high-speed Schlieren technique on the horizontal shock tube and primary experimental results are obtained, which show the change of the turbulent mixing region clearly. (authors)

  17. High-speed ground transportation development outside United States

    Energy Technology Data Exchange (ETDEWEB)

    Eastham, T.R. [Queen`s Univ., Kingston, Ontario (United Kingdom)

    1995-09-01

    This paper surveys the state of high-speed (in excess of 200 km/h) ground-transportation developments outside the United States. Both high-speed rail and Maglev systems are covered. Many vehicle systems capable of providing intercity service in the speed range 200--500 km/h are or will soon be available. The current state of various technologies, their implementation, and the near-term plans of countries that are most active in high-speed ground transportation development are reported.

  18. Numerical optimization of circulation control airfoil at high subsonic speed

    Science.gov (United States)

    Tai, T. C.; Kidwell, G. H., Jr.

    1984-01-01

    A numerical procedure for optimizing the design of the circulation control airfoil for use at high subsonic speeds is presented. The procedure consists of an optimization scheme coupled with a viscous potential flow analysis for the blowing jet. The desired airfoil is defined by a combination of three baseline shapes (cambered ellipse and cambered ellipse with drooped and spiraled trailing edges). The coefficients of these shapes are used as design variables in the optimization process. Under the constraints of lift augmentation and lift-to-drag ratios, the airfoil, optimized at free-stream Mach 0.54 and alpha = -2 degrees can be characterized as a cambered ellipse with a drooped trailing edge. Experimental tests support the performance improvement predicted by numerical optimization.

  19. Speed

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Speed. The rate of information transferred per second is the speed of the information. Measured in bits per second. Need for speed on the net: You-Tube phenomenon; IPTV; 3D Video telephony. Online gaming; HDTV.

  20. High capacity, high speed histogramming data acquisition memory

    International Nuclear Information System (INIS)

    Epstein, A.; Boulin, C.

    1996-01-01

    A double width CAMAC DRAM store module was developed for use as a histogramming memory in fast time-resolved synchrotron radiation applications to molecular biology. High speed direct memory modify (3 MHz) is accomplished by using a discrete DRAM controller and fast page mode access. The module can be configured using standard SIMMs to sizes of up to 64M-words. The word width is 16 bit and the module can handle overflows by storing the overflow addresses in a dedicated FIFO. Simultaneous front panel DMM/DMI access and CAMAC readout of the overflow addresses is supported

  1. High speed all-optical networks

    Science.gov (United States)

    Chlamtac, Imrich

    1993-01-01

    An inherent problem of conventional point-to-point WAN architectures is that they cannot translate optical transmission bandwidth into comparable user available throughput due to the limiting electronic processing speed of the switching nodes. This report presents the first solution to WDM based WAN networks that overcomes this limitation. The proposed Lightnet architecture takes into account the idiosyncrasies of WDM switching/transmission leading to an efficient and pragmatic solution. The Lightnet architecture trades the ample WDM bandwidth for a reduction in the number of processing stages and a simplification of each switching stage, leading to drastically increased effective network throughputs.

  2. High flow ceramic pot filters.

    Science.gov (United States)

    van Halem, D; van der Laan, H; Soppe, A I A; Heijman, S G J

    2017-11-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6-19 L h -1 ), but initial LRVs for E. coli of high flow filters was slightly lower than for regular ceramic pot filters. This disadvantage was, however, only temporarily as the clogging in high flow filters had a positive effect on the LRV for E. coli (from below 1 to 2-3 after clogging). Therefore, it can be carefully concluded that regular ceramic pot filters perform better initially, but after clogging, the high flow filters have a higher flow rate as well as a higher LRV for E. coli. To improve the initial performance of new high flow filters, it is recommended to further utilize residence time of the water in the receptacle, since additional E. coli inactivation was observed during overnight storage. Although a relationship was observed between flow rate and LRV of MS2 bacteriophages, both regular and high flow filters were unable to reach over 2 LRV. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. A high-speed interface for multi-channel analyzer

    International Nuclear Information System (INIS)

    Shen Ji; Zheng Zhong; Qiao Chong; Chen Ziyu; Ye Yunxiu; Ye Zhenyu

    2003-01-01

    This paper presents a high-speed computer interface for multi-channel analyzer based on DMA technique. Its essential principle and operating procedure are introduced. By the detecting of γ spectrum of 137 Cs with the interface, it's proved that the interface can meet the requirements of high-speed data acquisition

  4. Advancing high-speed rail policy in the United States.

    Science.gov (United States)

    2012-06-01

    This report builds on a review of international experience with high-speed rail projects to develop recommendations for a High-speed rail policy framework for the United States. The international review looked at the experience of Korea, Taiwan, Chin...

  5. High-Speed Photo-Polarimetry of Magnetic Cataclysmic Variables

    Directory of Open Access Journals (Sweden)

    S. B. Potter

    2015-02-01

    Full Text Available I review recent highlights of the SAAO High-speed Photo-POlarimeter (HIPPO on the study of magnetic Cataclysmic Variables. Its high-speed capabilities are demonstrated with example observations made of the intermediate polar NY Lup and the polar IGRJ14536-5522.

  6. High speed micromachining with high power UV laser

    Science.gov (United States)

    Patel, Rajesh S.; Bovatsek, James M.

    2013-03-01

    Increasing demand for creating fine features with high accuracy in manufacturing of electronic mobile devices has fueled growth for lasers in manufacturing. High power, high repetition rate ultraviolet (UV) lasers provide an opportunity to implement a cost effective high quality, high throughput micromachining process in a 24/7 manufacturing environment. The energy available per pulse and the pulse repetition frequency (PRF) of diode pumped solid state (DPSS) nanosecond UV lasers have increased steadily over the years. Efficient use of the available energy from a laser is important to generate accurate fine features at a high speed with high quality. To achieve maximum material removal and minimal thermal damage for any laser micromachining application, use of the optimal process parameters including energy density or fluence (J/cm2), pulse width, and repetition rate is important. In this study we present a new high power, high PRF QuasarR 355-40 laser from Spectra-Physics with TimeShiftTM technology for unique software adjustable pulse width, pulse splitting, and pulse shaping capabilities. The benefits of these features for micromachining include improved throughput and quality. Specific example and results of silicon scribing are described to demonstrate the processing benefits of the Quasar's available power, PRF, and TimeShift technology.

  7. Thermomechanical simulations and experimental validation for high speed incremental forming

    Science.gov (United States)

    Ambrogio, Giuseppina; Gagliardi, Francesco; Filice, Luigino; Romero, Natalia

    2016-10-01

    Incremental sheet forming (ISF) consists in deforming only a small region of the workspace through a punch driven by a NC machine. The drawback of this process is its slowness. In this study, a high speed variant has been investigated from both numerical and experimental points of view. The aim has been the design of a FEM model able to perform the material behavior during the high speed process by defining a thermomechanical model. An experimental campaign has been performed by a CNC lathe with high speed to test process feasibility. The first results have shown how the material presents the same performance than in conventional speed ISF and, in some cases, better material behavior due to the temperature increment. An accurate numerical simulation has been performed to investigate the material behavior during the high speed process confirming substantially experimental evidence.

  8. The use of high-speed imaging in education

    Science.gov (United States)

    Kleine, H.; McNamara, G.; Rayner, J.

    2017-02-01

    Recent improvements in camera technology and the associated improved access to high-speed camera equipment have made it possible to use high-speed imaging not only in a research environment but also specifically for educational purposes. This includes high-speed sequences that are created both with and for a target audience of students in high schools and universities. The primary goal is to engage students in scientific exploration by providing them with a tool that allows them to see and measure otherwise inaccessible phenomena. High-speed imaging has the potential to stimulate students' curiosity as the results are often surprising or may contradict initial assumptions. "Live" demonstrations in class or student- run experiments are highly suitable to have a profound influence on student learning. Another aspect is the production of high-speed images for demonstration purposes. While some of the approaches known from the application of high speed imaging in a research environment can simply be transferred, additional techniques must often be developed to make the results more easily accessible for the targeted audience. This paper describes a range of student-centered activities that can be undertaken which demonstrate how student engagement and learning can be enhanced through the use of high speed imaging using readily available technologies.

  9. A prediction of 3-D viscous flow and performance of the NASA Low-Speed Centrifugal Compressor

    Science.gov (United States)

    Moore, John; Moore, Joan G.

    1990-01-01

    A prediction of the three-dimensional turbulent flow in the NASA Low-Speed Centrifugal Compressor Impeller has been made. The calculation was made for the compressor design conditions with the specified uniform tip clearance gap. The predicted performance is significantly worse than that predicted in the NASA design study. This is explained by the high tip leakage flow in the present calculation and by the different model adopted for tip leakage flow mixing. The calculation gives an accumulation of high losses in the shroud/pressure-side quadrant near the exit of the impeller. It also predicts a region of meridional backflow near the shroud wall. Both of these flow features should be extensive enough in the NASA impeller to allow detailed flow measurements, leading to improved flow modeling. Recommendations are made for future flow studies in the NASA impeller.

  10. High-speed PIV applied to the wake of the NASA CRM model in ETW at high Re-number stall conditions for sub- and transonic speeds

    OpenAIRE

    Konrath, Robert; Geisler, Reinhard; Otter, Dirk; Philipp, Florian; Ehlers, Hauke; Agocs, Janos; Quest, Jürgen

    2015-01-01

    Within the framework of the EU project ESWIRP the Particle Image Velocimetry (PIV) using high-speed camera and laser has been used to measure the turbulent flow in the wake of a stalled aircraft wing. The measurements took place on the Common Research Model (CRM) provided by NASA in the pressurized cryogenic European Transonic Wind tunnel (ETW). A specific cryo-PIV system has been used and adapted for using high-speed PIV components under the cryogenic conditions of the wind tunnel faci...

  11. Novel high speed fiber-optic pressure sensor systems.

    Science.gov (United States)

    2014-03-01

    The goal of this project is to develop a complete test of this technology for high-speed, high-accuracy applications, specifically cost-effective data acquisition techniques and practical mounting methods tailored for the subject environment. The sec...

  12. Modern trends in designing high-speed trains

    Directory of Open Access Journals (Sweden)

    Golubović Snežana D.

    2015-01-01

    Full Text Available Increased advantages of railway transportation systems over other types of transportation systems in the past sixty years have been a result of an intensive development of the new generations of high-speed trains. Not only do these types of trains comply with the need for increased speed of transportation and make the duration of the journey shorter, but they also meet the demands for increased reliability, safety and direct application of energy efficiency to the transportation system itself. Along with increased train speed, the motion resistance is increased as well, whereby at speeds over 200 km/h the proportion of air resistance becomes the most dominant member. One of the most efficient measures for reducing air resistance, as well as other negative consequences of high-speed motion, is the development of the aerodynamic shape of the train. This paper presents some construction solutions that affect the aerodynamic properties of high-speed trains, first and foremost, the nose shape, as well as the similarities and differences of individual subsystems necessary for the functioning of modern high-speed rail systems. We analysed two approaches to solving the problem of the aerodynamic shape of the train and the appropriate infrastructure using the examples of Japan and France. Two models of high-speed trains, Shinkansen (Japan and TGV, i.e. AGV (France, have been discussed.

  13. Characterizing speed-independence of high-level designs

    DEFF Research Database (Denmark)

    Kishinevsky, Michael; Staunstrup, Jørgen

    1994-01-01

    This paper characterizes the speed-independence of high-level designs. The characterization is a condition on the design description ensuring that the behavior of the design is independent of the speeds of its components. The behavior of a circuit is modeled as a transition system, that allows data...... types, and internal as well as external non-determinism. This makes it possible to verify the speed-independence of a design without providing an explicit realization of the environment. The verification can be done mechanically. A number of experimental designs have been verified including a speed-independent...

  14. Investigation on Effect of Material Hardness in High Speed CNC End Milling Process

    OpenAIRE

    Dhandapani, N. V.; Thangarasu, V. S.; Sureshkannan, G.

    2015-01-01

    This research paper analyzes the effects of material properties on surface roughness, material removal rate, and tool wear on high speed CNC end milling process with various ferrous and nonferrous materials. The challenge of material specific decision on the process parameters of spindle speed, feed rate, depth of cut, coolant flow rate, cutting tool material, and type of coating for the cutting tool for required quality and quantity of production is addressed. Generally, decision made by the...

  15. Review of High-Speed Fiber Optic Grating Sensors Systems

    Energy Technology Data Exchange (ETDEWEB)

    Udd, E; Benterou, J; May, C; Mihailov, S J; Lu, P

    2010-03-24

    Fiber grating sensors can be used to support a wide variety of high speed measurement applications. This includes measurements of vibrations on bridges, traffic monitoring on freeways, ultrasonic detection to support non-destructive tests on metal plates and providing details of detonation events. This paper provides a brief overview of some of the techniques that have been used to support high speed measurements using fiber grating sensors over frequency ranges from 10s of kHz, to MHZ and finally toward frequencies approaching the GHz regime. Very early in the development of fiber grating sensor systems it was realized that a high speed fiber grating sensor system could be realized by placing an optical filter that might be a fiber grating in front of a detector so that spectral changes in the reflection from a fiber grating were amplitude modulated. In principal the only limitation on this type of system involved the speed of the output detector which with the development of high speed communication links moved from the regime of 10s of MHz toward 10s of GHz. The earliest deployed systems involved civil structures including measurements of the strain fields on composite utility poles and missile bodies during break tests, bridges and freeways. This was followed by a series of developments that included high speed fiber grating sensors to support nondestructive testing via ultrasonic wave detection, high speed machining and monitoring ship hulls. Each of these applications involved monitoring mechanical motion of structures and thus interest was in speeds up to a few 10s of MHz. Most recently there has been interest in using fiber grating to monitor the very high speed events such as detonations and this has led to utilization of fiber gratings that are consumed during an event that may require detection speeds of hundreds of MHz and in the future multiple GHz.

  16. High-speed LWR transients simulation for optimizing emergency response

    International Nuclear Information System (INIS)

    Wulff, W.; Cheng, H.S.; Lekach, S.V.; Mallen, A.N.; Stritar, A.

    1984-01-01

    The purpose of computer-assisted emergency response in nuclear power plants, and the requirements for achieving such a response, are presented. An important requirement is the attainment of realistic high-speed plant simulations at the reactor site. Currently pursued development programs for plant simulations are reviewed. Five modeling principles are established and a criterion is presented for selecting numerical procedures and efficient computer hardware to achieve high-speed simulations. A newly developed technology for high-speed power plant simulation is described and results are presented. It is shown that simulation speeds ten times greater than real-time process-speeds are possible, and that plant instrumentation can be made part of the computational loop in a small, on-site minicomputer. Additional technical issues are presented which must still be resolved before the newly developed technology can be implemented in a nuclear power plant

  17. Incorporating YBCO Coated Conductors in High-speed Superconducting Generators

    Science.gov (United States)

    2008-07-01

    4.0 kW/lb (8.82 kW/kg). The machine configuration chosen by GE for design was a homopolar inductor alternator (HIA) which locates the...extremely severe ac loss environment. Even if this is ultimately impossible for high speed generators, it may not preclude lower speed motors and

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

    Science.gov (United States)

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

    2008-11-01

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

  19. Tickling a high speed round jet

    Science.gov (United States)

    Arakeri, Vijay; Krothapalli, Anjaneyulu; Siddavaram, Vikram; Alkislar, Mehmet

    2001-11-01

    We have experimentally studied the effect of tickling a Mach 0.9 round jet with a set of microjets.Two dimensional velocity field measurements with PIV show a significant reduction in the turbulent intensities in the developing region of the jet with the activation of the microjets.Quantitatively,the axial and normal turbulence intensities are reduced by about 15respectively;even a larger effect is found on the magnitude of the correlation of axial and normal fluctuation intensities with a reduction of almost 40possible with a mass flow rate of the microjets being only about one percent of the main jet mass flow rate and hence justifying the use of the term `tickling`.The above findings are difficult to explain on the basis of stability considerations since there is very little change in the mean profile.Physically,the observed effect could be due to the alteration of the large eddy structures,which are so natural to a round jet,by the presence of the microjets.Exact nature of this interaction may be clarified with three dimensional PIV studies.It is expected that the tickling of the jet done as presently could have a favourable reflection in the aeroacoustics characteristics of the main jet.

  20. Surface grinding characteristics of ferrous metals under high-speed and speed-stroke grinding conditions

    International Nuclear Information System (INIS)

    Ghani, A.K.; Choudhury, I.A.; Ahim, M.B.

    1999-01-01

    Some ferrous metals have been ground under different conditions with high-speed and speed-stroke in surface grinding operation. The paper describes experimental investigation of grinding forces in grinding some ferrous metals with the application of cutting fluids. Grinding tests have been carried out on mild steel, assab steel and stainless steel with different combinations of down feed and cross feed. The wheel speed was 27 m/sec while the table speed was maintained at the maximum possible 25 m/min. The grindability has been evaluated by measuring the grinding forces, grinding ratio, and surface finish. Grinding forces have been plotted against down feed of the grinding wheel and cross feed of the table. It has been observed that the radial and tangential grinding forces in stainless steel were higher than those in assab steel and mild steel

  1. Technical report on prototype intelligent network flow optimization (INFLO) dynamic speed harmonization and queue warning.

    Science.gov (United States)

    2015-06-01

    This Technical Report on Prototype Intelligent Network Flow Optimization (INFLO) Dynamic Speed Harmonization and : Queue Warning is the final report for the project. It describes the prototyping, acceptance testing and small-scale : demonstration of ...

  2. Numerical analysis of flow induced noise propagation in supercavitating vehicles at subsonic speeds.

    Science.gov (United States)

    Ramesh, Sai Sudha; Lim, Kian Meng; Zheng, Jianguo; Khoo, Boo Cheong

    2014-04-01

    Flow supercavitation begins when fluid is accelerated over a sharp edge, usually at the nose of an underwater vehicle, where phase change occurs and causes low density gaseous cavity to gradually envelop the whole object (supercavity) and thereby enabling higher speeds of underwater vehicles. The process of supercavity inception/development by means of "natural cavitation" and its sustainment through ventilated cavitation result in turbulence and fluctuations at the water-vapor interface that manifest themselves as major sources of hydrodynamic noise. Therefore in the present context, three main sources are investigated, namely, (1) flow generated noise due to turbulent pressure fluctuations around the supercavity, (2) small scale pressure fluctuations at the vapor-water interface, and (3) pressure fluctuations due to direct impingement of ventilated gas-jets on the supercavity wall. An understanding of their relative contributions toward self-noise is very crucial for the efficient operation of high frequency acoustic sensors that facilitate the vehicle's guidance system. Qualitative comparisons of acoustic pressure distribution resulting from aforementioned sound sources are presented by employing a recently developed boundary integral method. By using flow data from a specially developed unsteady computational fluid dynamics solver for simulating supercavitating flows, the boundary-element method based acoustic solver was developed for computing flow generated sound.

  3. Trend on High-speed Power Line Communication Technology

    Science.gov (United States)

    Ogawa, Osamu

    High-speed power line communication (PLC) is useful technology to easily build the communication networks, because construction of new infrastructure is not necessary. In Europe and America, PLC has been used for broadband networks since the beginning of 21th century. In Japan, high-speed PLC was deregulated only indoor usage in 2006. Afterward it has been widely used for home area network, LAN in hotels and school buildings and so on. And recently, PLC is greatly concerned as communication technology for smart grid network. In this paper, the author surveys the high-speed PLC technology and its current status.

  4. High-speed AFM of human chromosomes in liquid

    Energy Technology Data Exchange (ETDEWEB)

    Picco, L M; Dunton, P G; Ulcinas, A; Engledew, D J; Miles, M J [H H Wills Physics Laboratory and IRC in Nanotechnology, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Hoshi, O; Ushiki, T [Division of Microscopic Anatomy and Bio-Imaging, Department of Cellular Function, Niigata University Graduate School of Medical and Dental Sciences, Asahimachi-Dori 1, Niigata, 951-8150 (Japan)], E-mail: m.j.miles@bristol.ac.uk

    2008-09-24

    Further developments of the previously reported high-speed contact-mode AFM are described. The technique is applied to the imaging of human chromosomes at video rate both in air and in water. These are the largest structures to have been imaged with high-speed AFM and the first imaging in liquid to be reported. A possible mechanism that allows such high-speed contact-mode imaging without significant damage to the sample is discussed in the context of the velocity dependence of the measured lateral force on the AFM tip.

  5. FPGA Flash Memory High Speed Data Acquisition

    Science.gov (United States)

    Gonzalez, April

    2013-01-01

    The purpose of this research is to design and implement a VHDL ONFI Controller module for a Modular Instrumentation System. The goal of the Modular Instrumentation System will be to have a low power device that will store data and send the data at a low speed to a processor. The benefit of such a system will give an advantage over other purchased binary IP due to the capability of allowing NASA to re-use and modify the memory controller module. To accomplish the performance criteria of a low power system, an in house auxiliary board (Flash/ADC board), FPGA development kit, debug board, and modular instrumentation board will be jointly used for the data acquisition. The Flash/ADC board contains four, 1 MSPS, input channel signals and an Open NAND Flash memory module with an analog to digital converter. The ADC, data bits, and control line signals from the board are sent to an Microsemi/Actel FPGA development kit for VHDL programming of the flash memory WRITE, READ, READ STATUS, ERASE, and RESET operation waveforms using Libero software. The debug board will be used for verification of the analog input signal and be able to communicate via serial interface with the module instrumentation. The scope of the new controller module was to find and develop an ONFI controller with the debug board layout designed and completed for manufacture. Successful flash memory operation waveform test routines were completed, simulated, and tested to work on the FPGA board. Through connection of the Flash/ADC board with the FPGA, it was found that the device specifications were not being meet with Vdd reaching half of its voltage. Further testing showed that it was the manufactured Flash/ADC board that contained a misalignment with the ONFI memory module traces. The errors proved to be too great to fix in the time limit set for the project.

  6. Online Speed Scaling Based on Active Job Count to Minimize Flow Plus Energy

    DEFF Research Database (Denmark)

    Lam, Tak-Wah; Lee, Lap Kei; To, Isaac K. K.

    2013-01-01

    This paper is concerned with online scheduling algorithms that aim at minimizing the total flow time plus energy usage. The results are divided into two parts. First, we consider the well-studied “simple” speed scaling model and show how to analyze a speed scaling algorithm (called AJC) that chan...

  7. Time resolved investigations on flow field and quasi wall shear stress of an impingement configuration with pulsating jets by means of high speed PIV and a surface hot wire array

    International Nuclear Information System (INIS)

    Janetzke, Timm; Nitsche, Wolfgang

    2009-01-01

    The effects of jet pulsation on flow field and quasi wall shear stress of an impingement configuration were investigated experimentally. The excitation Strouhal number and amplitude were varied as the most influential parameters. A line-array with three submerged air jets, and a confining plate were used. The flow field analysis by means of time resolved particle image velocimetry shows that the controlled excitation can considerably affect the near-field flow of an impinging jet array. These effects are visualized as organization of the coherent flow structures. Augmentation of the Kelvin-Helmholtz vortices in the jet shear layer depends on the Strouhal number and pulsation magnitude and can be associated with pairing of small scale vortices in the jet. A total maximum of vortex strength was observed when exciting with Sr = 0.82 and coincident high amplitudes. Time resolved interaction between impinging vortices and impingement plate boundary layer due to jet excitation was verified by using an array of 5 μm surface hot wires. Corresponding to the global flow field modification due to periodic jet pulsation, the impact of the vortex rings on the wall boundary layer is highly influenced by the above mentioned excitation parameters and reaches a maximum at Sr = 0.82.

  8. assessment of traffic flow on enugu highways using speed density

    African Journals Online (AJOL)

    HOD

    Corresponding author, tel: +234 – 806 – 435 – 0200 ... construction, maintenance and optimization of the highways using the ...... Research Part A: Policy and Practice 29(4), 273-281. 1995. ... relationships: Quality and Theory of Traffic Flow.

  9. Advanced Ultra-High Speed Motor for Drilling

    Energy Technology Data Exchange (ETDEWEB)

    Impact Technologies LLC; University of Texas at Arlington

    2007-03-31

    Three (3) designs have been made for two sizes, 6.91 cm (2.72 inch) and 4.29 cm (1.69 inch) outer diameters, of a patented inverted configured Permanent Magnet Synchronous Machines (PMSM) electric motor specifically for drilling at ultra-high rotational speeds (10,000 rpm) and that can utilize advanced drilling methods. Benefits of these motors are stackable power sections, full control (speed and direction) of downhole motors, flow hydraulics independent of motor operation, application of advanced drilling methods (water jetting and abrasive slurry jetting), and the ability of signal/power electric wires through motor(s). Key features of the final designed motors are: fixed non-rotating shaft with stator coils attached; rotating housing with permanent magnet (PM) rotor attached; bit attached to rotating housing; internal channel(s) in a nonrotating shaft; electric components that are hydrostatically isolated from high internal pressure circulating fluids ('muds') by static metal to metal seals; liquid filled motor with smoothed features for minimized turbulence in the motor during operation; and new inverted coated metal-metal hydrodynamic bearings and seals. PMSM, Induction and Switched Reluctance Machines (SRM), all pulse modulated, were considered, but PMSM were determined to provide the highest power density for the shortest motors. Both radial and axial electric PMSM driven motors were designed with axial designs deemed more rugged for ultra-high speed, drilling applications. The 6.91 cm (2.72 inch) OD axial inverted motor can generate 4.18KW (5.61 Hp) power at 10,000 rpm with a 4 Nm (2.95 ft-lbs) of torque for every 30.48 cm (12 inches) of power section. The 6.91 cm (2.72 inch) OD radial inverted motor can generate 5.03 KW (6.74 Hp) with 4.8 Nm (3.54 ft-lb) torque at 10,000 rpm for every 30.48 cm (12 inches) of power section. The 4.29 cm (1.69 inch) OD radial inverted motor can generate 2.56 KW (3.43 Hp) power with 2.44 Nm (1.8 ft-lb) torque at

  10. The coupling of high-speed high resolution experimental data and LES through data assimilation techniques

    Science.gov (United States)

    Harris, S.; Labahn, J. W.; Frank, J. H.; Ihme, M.

    2017-11-01

    Data assimilation techniques can be integrated with time-resolved numerical simulations to improve predictions of transient phenomena. In this study, optimal interpolation and nudging are employed for assimilating high-speed high-resolution measurements obtained for an inert jet into high-fidelity large-eddy simulations. This experimental data set was chosen as it provides both high spacial and temporal resolution for the three-component velocity field in the shear layer of the jet. Our first objective is to investigate the impact that data assimilation has on the resulting flow field for this inert jet. This is accomplished by determining the region influenced by the data assimilation and corresponding effect on the instantaneous flow structures. The second objective is to determine optimal weightings for two data assimilation techniques. The third objective is to investigate how the frequency at which the data is assimilated affects the overall predictions. Graduate Research Assistant, Department of Mechanical Engineering.

  11. Characterization of high speed synthetic jet actuators

    Science.gov (United States)

    Pikcilingis, Lucia

    Over the last 20 years, synthetic jets have been studied as a means for aerodynamic active flow control. Specifically, synthetic jets provide momentum transfer with zero-net mass flux, which has been proven to be effective for controlling flow fields. A synthetic jet is created by the periodic formation of vortex rings at its orifice due to the periodic motion of a piezoelectric disk(s). The present study seeks to optimize the performance of a synthetic jet actuator by utilizing different geometrical parameters such as disk thickness, orifice width and length, cavity height and cavity diameter, and different input parameters such as driving voltage and frequency. Two apparatuses were used with a cavity diameter of either 80 mm or 160 mm. Piezoelectric-based disks were provided by the Mide Corporation. Experiments were conducted using several synthetic jet apparatuses designed for various geometrical parameters utilizing a dual disk configuration. Velocity and temperature measurements were acquired at the center of the synthetic jet orifice using a temperature compensated hotwire and thermocouple probe. The disk(s) displacement was measured at the center of the disk with a laser displacement sensor. It was shown that the synthetic jets, having the 80 mm cavity diameter, are capable of exceeding peak velocities of 200 m/s with a relatively large orifice of dimensions AR = 12, hc* = 3, and hn* = 4. In addition, the conditions at which the disks were manufactured had minimal effect on the performance of the jet, except for the pair with overnight resting time as opposed to less than an hour resting time for the control units. Altering the tab style of the disks, where the tab allows the electrical circuit to be exposed for external power connection, showed that a thin fragile tab versus a tab of the same thickness as the disk has minimal effect on the performance but affects the durability of the disk due to the fragility or robustness of the tab. The synthetic jets

  12. Perceived enjoyment, concentration, intention, and speed violation behavior: Using flow theory and theory of planned behavior.

    Science.gov (United States)

    Atombo, Charles; Wu, Chaozhong; Zhang, Hui; Wemegah, Tina D

    2017-10-03

    Road accidents are an important public health concern, and speeding is a major contributor. Although flow theory (FLT) is a valid model for understanding behavior, currently the nature of the roles and interplay of FLT constructs within the theory of planned behavior (TPB) framework when attempting to explain the determinants of motivations for intention to speed and speeding behavior of car drivers is not yet known. The study aims to synthesize TPB and FLT in explaining drivers of advanced vehicles intentions to speed and speed violation behaviors and evaluate factors that are critical for explaining intention and behavior. The hypothesized model was validated using a sample collected from 354 fully licensed drivers of advanced vehicles, involving 278 males and 76 females on 2 occasions separated by a 3-month interval. During the first of the 2 occasions, participants completed questionnaire measures of TPB and FLT variables. Three months later, participants' speed violation behaviors were assessed. The study observed a significant positive relationship between the constructs. The proposed model accounted for 51 and 45% of the variance in intention to speed and speed violation behavior, respectively. The independent predictors of intention were enjoyment, attitude, and subjective norm. The independent predictors of speed violation behavior were enjoyment, concentration, intention, and perceived behavioral control. The findings suggest that safety interventions for preventing speed violation behaviors should be aimed at underlying beliefs influencing the speeding behaviors of drivers of advanced vehicles. Furthermore, perceived enjoyment is of equal importance to driver's intention, influencing speed violation behavior.

  13. Children's Brain Responses to Optic Flow Vary by Pattern Type and Motion Speed.

    Directory of Open Access Journals (Sweden)

    Rick O Gilmore

    Full Text Available Structured patterns of global visual motion called optic flow provide crucial information about an observer's speed and direction of self-motion and about the geometry of the environment. Brain and behavioral responses to optic flow undergo considerable postnatal maturation, but relatively little brain imaging evidence describes the time course of development in motion processing systems in early to middle childhood, a time when psychophysical data suggest that there are changes in sensitivity. To fill this gap, electroencephalographic (EEG responses were recorded in 4- to 8-year-old children who viewed three time-varying optic flow patterns (translation, rotation, and radial expansion/contraction at three different speeds (2, 4, and 8 deg/s. Modulations of global motion coherence evoked coherent EEG responses at the first harmonic that differed by flow pattern and responses at the third harmonic and dot update rate that varied by speed. Pattern-related responses clustered over right lateral channels while speed-related responses clustered over midline channels. Both children and adults show widespread responses to modulations of motion coherence at the second harmonic that are not selective for pattern or speed. The results suggest that the developing brain segregates the processing of optic flow pattern from speed and that an adult-like pattern of neural responses to optic flow has begun to emerge by early to middle childhood.

  14. Anechoic wind tunnel tests on high-speed train bogie aerodynamic noise

    OpenAIRE

    Latorre Iglesias, E.; Thompson, D.; Smith, M.; Kitagawa, T.; Yamazaki, N.

    2016-01-01

    Aerodynamic noise becomes a significant noise source at speeds normally reached by high-speed trains. The train bogies are identified as important sources of aerodynamic noise. Due to the difficulty to assess this noise source carrying out field tests, wind tunnel tests offer many advantages. Tests were performed in the large-scale low-noise anechoic wind tunnel at Maibara, Japan, using a 1/7 scale train car and bogie model for a range of flow speeds between 50, 76, 89 and 100 m/s. The depend...

  15. High speed photometry of AN UMa

    International Nuclear Information System (INIS)

    Imamura, J.N.; Steiman-Cameron, T.Y.; Durisen, R.H.

    1985-01-01

    As a class, the AM Her objects exhibit temporal variability on time scales ranging from seconds to years. Most of the variations can be adequately described by ''shot noise'' models (Cordova and Mason 1982). Exceptions to this are the strictly periodic features modulated on the orbital periods of the systems (typically several hours) and the one to two second features which show up as ''excesses'' of power in the time averaged power spectra of AN UMa (Middleditch 1982) and E1405-451 (Mason et al. 1983; Larsson 1985). It has been suggested that the short time scale features are due to an oscillatory ''instability'' of radiative accretion shocks discovered by Langer, Chanmugam, and Shaviv (1981, 1982). This is an interesting suggestion because, if true, it would allow the masses of the accreting white dwarfs to be inferred and would provide other significant constraints on the physics of the accretion flows (see Langer et al. 1981, 1982; Chevalier and Imamura 1982; Imamura, Wolff, and Durisen 1984; Imamura 1985). Unfortunately, a direct physical relationship between the one to two second optical variations and shock oscillations has not yet been demonstrated. Because of the potential importance of such a result further study of these systems is clearly warranted. In this work, we examine the short time scale behavior of AN UMa in more detail and improve on the work of Middleditch (1982) by resolving the feature in time

  16. High Speed Frame Synchronization and Viterbi Decoding

    DEFF Research Database (Denmark)

    Paaske, Erik; Justesen, Jørn; Larsen, Knud J.

    1996-01-01

    The purpose of Phase 1 of the study is to describe the system structure and algorithms in sufficient detail to allow drawing the high level architecture of units containing frame synchronization and Viterbi decoding. The systems we consider are high data rate space communication systems. Also...... components. Node synchronization performed within a Viterbi decoder is discussed, and algorithms for frame synchronization are described and analyzed. We present a list of system configurations that we find potentially useful. Further, the high level architecture of units that contain frame synchronization...... and various other functions needed in a complete system is presented. Two such units are described, one for placement before the Viterbi decoder and another for placement after the decoder. The high level architectures of three possible implementations of Viterbi decoders are described: The first...

  17. High-speed rail turnout literature review : final report.

    Science.gov (United States)

    2016-08-01

    High-speed rail (HSR) turnout design criteria generally address unbalanced lateral acceleration or cant deficiency (CD), cant deficiency change rate (CDCR), and entry and exit jerk. Various countries have adopted different design values for their HSR...

  18. Multicast Performance Analysis for High-Speed Torus Networks

    National Research Council Canada - National Science Library

    Oral, S; George, A

    2002-01-01

    ... for unicast-based and path-based multicast communication on high-speed torus networks. Software-based multicast performance results of selected algorithms on a 16-node Scalable Coherent Interface (SCI) torus are given...

  19. High speed railway track dynamics models, algorithms and applications

    CERN Document Server

    Lei, Xiaoyan

    2017-01-01

    This book systematically summarizes the latest research findings on high-speed railway track dynamics, made by the author and his research team over the past decade. It explores cutting-edge issues concerning the basic theory of high-speed railways, covering the dynamic theories, models, algorithms and engineering applications of the high-speed train and track coupling system. Presenting original concepts, systematic theories and advanced algorithms, the book places great emphasis on the precision and completeness of its content. The chapters are interrelated yet largely self-contained, allowing readers to either read through the book as a whole or focus on specific topics. It also combines theories with practice to effectively introduce readers to the latest research findings and developments in high-speed railway track dynamics. It offers a valuable resource for researchers, postgraduates and engineers in the fields of civil engineering, transportation, highway & railway engineering.

  20. Progress in the development of niobium alloyed high speed steel

    International Nuclear Information System (INIS)

    Guimaraes, J.R.C.

    1987-01-01

    The development of economy-grades of niobium alloyed high speed steel is described. Both the metallurgical concepts behind the steel design and the results of performance tests are presented. (Author) [pt

  1. High Speed Frame Synchronization and Viterbi Decoding

    DEFF Research Database (Denmark)

    Paaske, Erik; Justesen, Jørn; Larsen, Knud J.

    1998-01-01

    The study has been divided into two phases. The purpose of Phase 1 of the study was to describe the system structure and algorithms in sufficient detail to allow drawing the high level architecture of units containing frame synchronization and Viterbi decoding. After selection of which specific...... potentially useful.Algorithms for frame synchronization are described and analyzed. Further, the high level architecture of units that contain frame synchronization and various other functions needed in a complete system is presented. Two such units are described, one for placement before the Viterbi decoder...... towards a realization in an FPGA.Node synchronization performed within a Viterbi decoder is discussed, and the high level architectures of three possible implementations of Viterbi decoders are described: The first implementation uses a number of commercially available decoders while the the two others...

  2. High Speed Rail (HSR) in the United States

    Science.gov (United States)

    2009-12-08

    announced that it will expand the capacity on its aging high speed line between Tokyo and Osaka, the most heavily traveled intercity rail segment in the...United States, in most of these countries intercity rail travel (including both conventional and high speed rail) represents less than 10% of all...that is sometimes mentioned by its advocates. Intercity passenger rail transport is relatively safe, at least compared with highway travel . And HSR in

  3. Application of Beyond Bound Decoding for High Speed Optical Communications

    DEFF Research Database (Denmark)

    Li, Bomin; Larsen, Knud J.; Vegas Olmos, Juan José

    2013-01-01

    This paper studies the application of beyond bound decoding method for high speed optical communications. This hard-decision decoding method outperforms traditional minimum distance decoding method, with a total net coding gain of 10.36 dB.......This paper studies the application of beyond bound decoding method for high speed optical communications. This hard-decision decoding method outperforms traditional minimum distance decoding method, with a total net coding gain of 10.36 dB....

  4. Nanocrystalline Ni-Co Alloy Synthesis by High Speed Electrodeposition

    OpenAIRE

    Idris, Jamaliah; Christian, Chukwuekezie; Gaius, Eyu

    2013-01-01

    Electrodeposition of nanocrystals is economically and technologically viable production path for the synthesis of pure metals and alloys both in coatings and bulk form. The study presents nanocrystalline Ni-Co alloy synthesis by high speed electrodeposition. Nanocrystalline Ni-Co alloys coatings were prepared by direct current (DC) and deposited directly on steel and aluminum substrates without any pretreatment, using high speed electrodeposition method. The influence of the electrolysis par...

  5. Development of a super high speed railway and ML 100

    Energy Technology Data Exchange (ETDEWEB)

    Usami, Y

    1973-07-01

    A history of the development progress is given, followed by a discussion of the propulsion system for a super high speed railway-structure. Induction linear motors and synchronous linear motors are discussed in some detail. The maintenance system is then described (basic test apparatus-rotary type superconductive magnetic force maintenance system, etc.). Experiments using a linear running superconductive magnetic test car are discussed. Developments of super high speed railways in America, France, England, West Germany, etc. are described.

  6. Double Tunneling Injection Quantum Dot Lasers for High Speed Operation

    Science.gov (United States)

    2017-10-23

    Double Tunneling-Injection Quantum Dot Lasers for High -Speed Operation The views, opinions and/or findings contained in this report are those of...SECURITY CLASSIFICATION OF: 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES 12. DISTRIBUTION AVAILIBILITY STATEMENT 6...State University Title: Double Tunneling-Injection Quantum Dot Lasers for High -Speed Operation Report Term: 0-Other Email: asryan@vt.edu Distribution

  7. High-speed optical signal processing using time lenses

    DEFF Research Database (Denmark)

    Galili, Michael; Hu, Hao; Guan, Pengyu

    2015-01-01

    This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle.......This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle....

  8. Integrated computer network high-speed parallel interface

    International Nuclear Information System (INIS)

    Frank, R.B.

    1979-03-01

    As the number and variety of computers within Los Alamos Scientific Laboratory's Central Computer Facility grows, the need for a standard, high-speed intercomputer interface has become more apparent. This report details the development of a High-Speed Parallel Interface from conceptual through implementation stages to meet current and future needs for large-scle network computing within the Integrated Computer Network. 4 figures

  9. High speed data transmission at the Superconducting Super Collider

    International Nuclear Information System (INIS)

    Leskovar, B.

    1990-04-01

    High speed data transmission using fiber optics in the data acquisition system of the Superconducting Super Collider has been investigated. Emphasis is placed on the high speed data transmission system overview, the local data network and on subassemblies, such as optical transmitters and receivers. Also, the performance of candidate subassemblies having a low power dissipation for the data acquisition system is discussed. 14 refs., 5 figs

  10. California statewide model for high-speed rail

    OpenAIRE

    Outwater, Maren; Tierney, Kevin; Bradley, Mark; Sall, Elizabeth; Kuppam, Arun; Modugala, Vamsee

    2010-01-01

    The California High Speed Rail Authority (CHSRA) and the Metropolitan Transportation Commission (MTC) have developed a new statewide model to support evaluation of high-speed rail alternatives in the State of California. This statewide model will also support future planning activities of the California Department of Transportation (Caltrans). The approach to this statewide model explicitly recognizes the unique characteristics of intraregional travel demand and interregional travel demand. A...

  11. Minimum Plate Thickness in High-Speed Craft

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    The minimum plate thickness requirements specified by the classification societies for high-speed craft are supposed to ensure adequate resistance to impact loads such as collision with floating objects and objects falling on the deck. The paper presents analytical methods of describing such impact...... phenomena and proposes performance requirements instead of thickness requirements for hull panels in high-speed craft made of different building materials....

  12. High-speed precision motion control

    CERN Document Server

    Yamaguchi, Takashi; Pang, Chee Khiang

    2011-01-01

    Written for researchers and postgraduate students in Control Engineering, as well as professionals in the Hard Disk Drive industry, this book discusses high-precision and fast servo controls in Hard Disk Drives (HDDs). The editors present a number of control algorithms that enable fast seeking and high precision positioning, and propose problems from commercial products, making the book valuable to researchers in HDDs. Each chapter is self contained, and progresses from concept to technique, present application examples that can be used within automotive, aerospace, aeronautical, and manufactu

  13. A reference Pelton turbine - High speed visualization in the rotating frame

    Science.gov (United States)

    Solemslie, Bjørn W.; Dahlhaug, Ole G.

    2016-11-01

    To enable a detailed study the flow mechanisms effecting the flow within the reference Pelton runner designed at the Waterpower Laboratory (NTNLT) a flow visualization system has been developed. The system enables high speed filming of the hydraulic surface of a single bucket in the rotating frame of reference. It is built with an angular borescopes adapter entering the turbine along the rotational axis and a borescope embedded within a bucket. A stationary high speed camera located outside the turbine housing has been connected to the optical arrangement by a non-contact coupling. The view point of the system includes the whole hydraulic surface of one half of a bucket. The system has been designed to minimize the amount of vibrations and to ensure that the vibrations felt by the borescope are the same as those affecting the camera. The preliminary results captured with the system are promising and enable a detailed study of the flow within the turbine.

  14. A high-speed analog neural processor

    NARCIS (Netherlands)

    Masa, P.; Masa, Peter; Hoen, Klaas; Hoen, Klaas; Wallinga, Hans

    1994-01-01

    Targeted at high-energy physics research applications, our special-purpose analog neural processor can classify up to 70 dimensional vectors within 50 nanoseconds. The decision-making process of the implemented feedforward neural network enables this type of computation to tolerate weight

  15. Simulation of High-Speed Droplet Impact Against Dry Substrates with Partial Velocity Slip

    Science.gov (United States)

    Kondo, Tomoki; Ando, Keita

    2017-11-01

    High-speed droplet impact can be used to clean substrates such as silicon wafers. Radially spreading shear flow after the impact may allow for mechanically removing contaminant particles at substrate surfaces. Since it is a big challenge to experimentally explore such complicated flow that exhibits contact line motion and water hammer, its flow feature is not well understood. Here, we aim to numerically evaluate shear flow caused by the impact of a spherical water droplet (of submillimeter sizes) at high speed (up to 50 m/s) against a dry rigid wall. We model the flow based on compressible Navier-Stokes equations with Stokes' hypothesis and solve them by a high-order-accurate finite volume method equipped with shock and interface capturing. To treat the motion of a contact line between the three phases (the droplet, the rigid wall, and the ambient air) in a robust manner, we permit velocity slip at the wall with Navier's model, for wall slip is known to come into play under steep velocity gradients that can arise from high-speed droplet impact. In our presentation, we will examine radially spreading flow after the droplet impact and the resulting wall shear stress generation from the simulation. This work was supported by JSPS KAKENHI Grant Number JP17J02211.

  16. Effect of variations in air speed on cross-flow cylinder frosting

    International Nuclear Information System (INIS)

    Monaghan, P.F.; Cassidy, S.F.; Oosthuizen, P.H.

    1990-01-01

    In this paper the effect of fluctuating air speed on frost growth and heat transfer to a cylinder in cross-flow is discussed. Frost-growth of up to 20 hours is simulated using an experimentally validated finite difference computer model. Graphical results are presented for frost mass, frost depth, frost surface temperature and heat transfer versus time under both steady and fluctuating air speed conditions. In general, it is found that a thinner, more dense frost layer develops under fluctuating air speed conditions giving improved heat transfer. This phenomenon may be explained by the increased frequency of frost surface thaw/freeze cycles when fluctuating air speed conditions prevail

  17. Modeling and numerical techniques for high-speed digital simulation of nuclear power plants

    International Nuclear Information System (INIS)

    Wulff, W.; Cheng, H.S.; Mallen, A.N.

    1987-01-01

    Conventional computing methods are contrasted with newly developed high-speed and low-cost computing techniques for simulating normal and accidental transients in nuclear power plants. Six principles are formulated for cost-effective high-fidelity simulation with emphasis on modeling of transient two-phase flow coolant dynamics in nuclear reactors. Available computing architectures are characterized. It is shown that the combination of the newly developed modeling and computing principles with the use of existing special-purpose peripheral processors is capable of achieving low-cost and high-speed simulation with high-fidelity and outstanding user convenience, suitable for detailed reactor plant response analyses

  18. Three-Dimensional Numerical Analysis of an Operating Helical Rotor Pump at High Speeds and High Pressures including Cavitation

    Directory of Open Access Journals (Sweden)

    Zhou Yang

    2017-01-01

    Full Text Available High pressures, high speeds, low noise and miniaturization is the direction of development in hydraulic pump. According to the development trend, an operating helical rotor pump (HRP at high speeds and high pressures has been designed and produced, which rotational speed can reach 12000r/min and outlet pressure is as high as 25MPa. Three-dimensional simulation with and without cavitation inside the HRP is completed by the means of the computational fluid dynamics (CFD in this paper, which contributes to understand the complex fluid flow inside it. Moreover, the influences of the rotational speeds of the HRP with and without cavitation has been simulated at 25MPa.

  19. High-speed X-ray topography

    International Nuclear Information System (INIS)

    Eckers, W.; Oppolzer, H.

    1977-01-01

    The investigation of lattice defects in semiconductor crystals by conventional X-ray diffraction topography is very time-consuming. Exposure times can be reduced by using high-intensity X-rays and X-ray image intensifiers. The described system comprises a high-power rotating-anode X-ray tube, a remote-controlled X-ray topography camera, and a television system operating with an X-ray sensing VIDICON. System performance is demonstrated with reference to exploratory examples. The exposure time for photographic plates is reduced to 1/20 and for the X-ray TV system (resolution of the order of 30 μm) to 1/100 relative to that required when using a conventional topography system. (orig.) [de

  20. High-speed quantum networking by ship

    Science.gov (United States)

    Devitt, Simon J.; Greentree, Andrew D.; Stephens, Ashley M.; van Meter, Rodney

    2016-11-01

    Networked entanglement is an essential component for a plethora of quantum computation and communication protocols. Direct transmission of quantum signals over long distances is prevented by fibre attenuation and the no-cloning theorem, motivating the development of quantum repeaters, designed to purify entanglement, extending its range. Quantum repeaters have been demonstrated over short distances, but error-corrected, global repeater networks with high bandwidth require new technology. Here we show that error corrected quantum memories installed in cargo containers and carried by ship can provide a exible connection between local networks, enabling low-latency, high-fidelity quantum communication across global distances at higher bandwidths than previously proposed. With demonstrations of technology with sufficient fidelity to enable topological error-correction, implementation of the quantum memories is within reach, and bandwidth increases with improvements in fabrication. Our approach to quantum networking avoids technological restrictions of repeater deployment, providing an alternate path to a worldwide Quantum Internet.

  1. High speed gated x-ray imagers

    International Nuclear Information System (INIS)

    Kilkenny, J.D.; Bell, P.; Hanks, R.; Power, G.; Turner, R.E.; Wiedwald, J.

    1988-01-01

    Single and multi-frame gated x-ray images with time-resolution as fast as 150 psec are described. These systems are based on the gating of microchannel plates in a stripline configuration. The gating voltage comes from the avalanche breakdown of reverse biased p-n junction producing high power voltage pulses as short as 70 psec. Results from single and four frame x-ray cameras used on Nova are described. 8 refs., 9 figs

  2. Research on the tool holder mode in high speed machining

    Science.gov (United States)

    Zhenyu, Zhao; Yongquan, Zhou; Houming, Zhou; Xiaomei, Xu; Haibin, Xiao

    2018-03-01

    High speed machining technology can improve the processing efficiency and precision, but also reduce the processing cost. Therefore, the technology is widely regarded in the industry. With the extensive application of high-speed machining technology, high-speed tool system has higher and higher requirements on the tool chuck. At present, in high speed precision machining, several new kinds of clip heads are as long as there are heat shrinkage tool-holder, high-precision spring chuck, hydraulic tool-holder, and the three-rib deformation chuck. Among them, the heat shrinkage tool-holder has the advantages of high precision, high clamping force, high bending rigidity and dynamic balance, etc., which are widely used. Therefore, it is of great significance to research the new requirements of the machining tool system. In order to adapt to the requirement of high speed machining precision machining technology, this paper expounds the common tool holder technology of high precision machining, and proposes how to select correctly tool clamping system in practice. The characteristics and existing problems are analyzed in the tool clamping system.

  3. Analysis of Low Speed Stall Aerodynamics of a Swept Wing with Laminar Flow Glove

    Science.gov (United States)

    Bui, Trong T.

    2014-01-01

    Reynolds-Averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) analysis was conducted to study the low-speed stall aerodynamics of a GIII aircraft's swept wing modified with a laminar-flow wing glove. The stall aerodynamics of the gloved wing were analyzed and compared with the unmodified wing for the flight speed of 120 knots and altitude of 2300 ft above mean sea level (MSL). The Star-CCM+ polyhedral unstructured CFD code was first validated for wing stall predictions using the wing-body geometry from the First American Institute of Aeronautics and Astronautics (AIAA) CFD High-Lift Prediction Workshop. It was found that the Star-CCM+ CFD code can produce results that are within the scattering of other CFD codes considered at the workshop. In particular, the Star-CCM+ CFD code was able to predict wing stall for the AIAA wing-body geometry to within 1 degree of angle of attack as compared to benchmark wind-tunnel test data. Current results show that the addition of the laminar-flow wing glove causes the gloved wing to stall much earlier than the unmodified wing. Furthermore, the gloved wing has a different stall characteristic than the clean wing, with no sharp lift drop-off at stall for the gloved wing.

  4. Analysis of Low-Speed Stall Aerodynamics of a Swept Wing with Laminar-Flow Glove

    Science.gov (United States)

    Bui, Trong T.

    2014-01-01

    Reynolds-Averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) analysis was conducted to study the low-speed stall aerodynamics of a GIII aircraft's swept wing modified with a laminar-flow wing glove. The stall aerodynamics of the gloved wing were analyzed and compared with the unmodified wing for the flight speed of 120 knots and altitude of 2300 ft above mean sea level (MSL). The Star-CCM+ polyhedral unstructured CFD code was first validated for wing stall predictions using the wing-body geometry from the First American Institute of Aeronautics and Astronautics (AIAA) CFD High-Lift Prediction Workshop. It was found that the Star-CCM+ CFD code can produce results that are within the scattering of other CFD codes considered at the workshop. In particular, the Star-CCM+ CFD code was able to predict wing stall for the AIAA wing-body geometry to within 1 degree of angle of attack as compared to benchmark wind-tunnel test data. Current results show that the addition of the laminar-flow wing glove causes the gloved wing to stall much earlier than the unmodified wing. Furthermore, the gloved wing has a different stall characteristic than the clean wing, with no sharp lift drop-off at stall for the gloved wing.

  5. High-speed and high-ratio referential genome compression.

    Science.gov (United States)

    Liu, Yuansheng; Peng, Hui; Wong, Limsoon; Li, Jinyan

    2017-11-01

    The rapidly increasing number of genomes generated by high-throughput sequencing platforms and assembly algorithms is accompanied by problems in data storage, compression and communication. Traditional compression algorithms are unable to meet the demand of high compression ratio due to the intrinsic challenging features of DNA sequences such as small alphabet size, frequent repeats and palindromes. Reference-based lossless compression, by which only the differences between two similar genomes are stored, is a promising approach with high compression ratio. We present a high-performance referential genome compression algorithm named HiRGC. It is based on a 2-bit encoding scheme and an advanced greedy-matching search on a hash table. We compare the performance of HiRGC with four state-of-the-art compression methods on a benchmark dataset of eight human genomes. HiRGC takes compress about 21 gigabytes of each set of the seven target genomes into 96-260 megabytes, achieving compression ratios of 217 to 82 times. This performance is at least 1.9 times better than the best competing algorithm on its best case. Our compression speed is also at least 2.9 times faster. HiRGC is stable and robust to deal with different reference genomes. In contrast, the competing methods' performance varies widely on different reference genomes. More experiments on 100 human genomes from the 1000 Genome Project and on genomes of several other species again demonstrate that HiRGC's performance is consistently excellent. The C ++ and Java source codes of our algorithm are freely available for academic and non-commercial use. They can be downloaded from https://github.com/yuansliu/HiRGC. jinyan.li@uts.edu.au. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  6. High flow ceramic pot filters

    OpenAIRE

    van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

    2017-01-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6–19 L h−1), but initial LRVs for E. coli o...

  7. Design optimization of high speed gamma-ray tomography

    International Nuclear Information System (INIS)

    Maad, Rachid

    2009-01-01

    This thesis concerns research and development of efficient gamma-ray systems for high speed tomographic imaging of hydrocarbon flow dynamics with a particular focus on gas liquid imaging. The Bergen HSGT (High Speed Gamma-ray Tomograph) based on instant imaging with a fixed source-detector geometry setup, has been thoroughly characterized with a variety of image reconstruction algorithms and flow conditions. Experiments in flow loops have been carried out for reliable characterization and error analysis, static flow phantoms have been applied for the majority of experiments to provide accurate imaging references. A semi-empirical model has been developed for estimation of the contribution of scattered radiation to each HSGT detector and further for correction of this contribution prior to data reconstruction. The Bergen FGGT (Flexible Geometry Gamma-ray Tomograph) has been further developed, particularly on the software side. The system emulates any fan beam tomography. Based on user input of geometry and other conditions, the new software perform scanning, data acquisition and storage, and also weight matrix calculation and image reconstruction with the desired method. The FGGT has been used for experiments supporting those carried out with the HSGT, and in addition for research on other fan beam geometries suitable for hydrocarbon flow imaging applications. An instant no-scanning tomograph like the HSGT has no flexibility with respect to change of geometry, which usually is necessary when applying the tomograph for a new application. A computer controlled FGGT has been designed and built at the UoB. The software developed for the FGGT controls the scanning procedure, the data acquisition, calculates the weight matrix necessary for the image reconstruction, reconstructs the image using standard reconstruction algorithms, and calculates the error of the reconstructed image. The performance of the geometry has been investigated using a 100 mCi 241 Am disk source, a

  8. Modulation of walking speed by changing optic flow in persons with stroke

    Directory of Open Access Journals (Sweden)

    Lamontagne Anouk

    2007-06-01

    Full Text Available Abstract Background Walking speed, which is often reduced after stroke, can be influenced by the perception of optic flow (OF speed. The present study aims to: 1 compare the modulation of walking speed in response to OF speed changes between persons with stroke and healthy controls and 2 investigate whether virtual environments (VE manipulating OF speed can be used to promote volitional changes in walking speed post stroke. Methods Twelve persons with stroke and 12 healthy individuals walked on a self-paced treadmill while viewing a virtual corridor in a helmet-mounted display. Two experiments were carried out on the same day. In experiment 1, the speed of an expanding OF was varied sinusoidally at 0.017 Hz (sine duration = 60 s, from 0 to 2 times the subject's comfortable walking speed, for a total duration of 5 minutes. In experiment 2, subjects were exposed to expanding OFs at discrete speeds that ranged from 0.25 to 2 times their comfortable speed. Each test trial was paired with a control trial performed at comfortable speed with matching OF. For each of the test trials, subjects were instructed to walk the distance within the same time as during the immediately preceding control trial. VEs were controlled by the CAREN-2 system (Motek. Instantaneous changes in gait speed (experiment 1 and the ratio of speed changes in the test trial over the control trial (experiment 2 were contrasted between the two groups of subjects. Results When OF speed was changing continuously (experiment 1, an out-of-phase modulation was observed in the gait speed of healthy subjects, such that slower OFs induced faster walking speeds, and vice versa. Persons with stroke displayed weaker (p 0.05, T-test. Conclusion Stroke affects the modulation of gait speed in response to changes in the perception of movement through different OF speeds. Nevertheless, the preservation of even a modest modulation enabled the persons with stroke to increase walking speed when

  9. Sphinx, the high speed flash radiography

    International Nuclear Information System (INIS)

    Anon.

    1997-01-01

    Sphinx (Nanosecond Pulse X-Photon Source) is the most compact (0.1 m 3 ) existing system which can generates short pulses (10 to 30 nanoseconds) of 5 to 180 keV X-photon radiation with a repeating cadence of 100 pulses per second and doses which can reach 2 mR at 1 m. This system was developed by the Research Group on Energetics of Ionized Media (GREMI) from the CNRS (French National Center for Scientific Research) and the University of Orleans (France). Sphinx is the smallest device from a series of compact X-ray sources ranging from 5 to 400 keV. These devices can have several possible applications such as the study of ultra-fast phenomena, the high cadence flash radiography in medicine, biology, materials studies, pre-ionizing of gas lasers, self-excitation and photo-ionization of atoms, molecules or aggregates. (J.S.)

  10. Control structures for high speed processors

    Science.gov (United States)

    Maki, G. K.; Mankin, R.; Owsley, P. A.; Kim, G. M.

    1982-01-01

    A special processor was designed to function as a Reed Solomon decoder with throughput data rate in the Mhz range. This data rate is significantly greater than is possible with conventional digital architectures. To achieve this rate, the processor design includes sequential, pipelined, distributed, and parallel processing. The processor was designed using a high level language register transfer language. The RTL can be used to describe how the different processes are implemented by the hardware. One problem of special interest was the development of dependent processes which are analogous to software subroutines. For greater flexibility, the RTL control structure was implemented in ROM. The special purpose hardware required approximately 1000 SSI and MSI components. The data rate throughput is 2.5 megabits/second. This data rate is achieved through the use of pipelined and distributed processing. This data rate can be compared with 800 kilobits/second in a recently proposed very large scale integration design of a Reed Solomon encoder.

  11. Pulse-burst PIV in a high-speed wind tunnel

    International Nuclear Information System (INIS)

    Beresh, Steven; Kearney, Sean; Wagner, Justin; Guildenbecher, Daniel; Henfling, John; Spillers, Russell; Pruett, Brian; Jiang, Naibo; Slipchenko, Mikhail; Mance, Jason; Roy, Sukesh

    2015-01-01

    Time-resolved particle image velocimetry (TR-PIV) has been achieved in a high-speed wind tunnel, providing velocity field movies of compressible turbulence events. The requirements of high-speed flows demand greater energy at faster pulse rates than possible with the TR-PIV systems developed for low-speed flows. This has been realized using a pulse-burst laser to obtain movies at up to 50 kHz, with higher speeds possible at the cost of spatial resolution. The constraints imposed by use of a pulse-burst laser are limited burst duration of 10.2 ms and a low duty cycle for data acquisition. Pulse-burst PIV has been demonstrated in a supersonic jet exhausting into a transonic crossflow and in transonic flow over a rectangular cavity. The velocity field sequences reveal the passage of turbulent structures and can be used to find velocity power spectra at every point in the field, providing spatial distributions of acoustic modes. The present work represents the first use of TR-PIV in a high-speed ground-test facility. (paper)

  12. Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines

    Directory of Open Access Journals (Sweden)

    M. M. Pedersen

    2017-11-01

    Full Text Available In this paper an alternative method to evaluate power performance and loads on wind turbines using a blade-mounted flow sensor is investigated. The hypothesis is that the wind speed measured at the blades has a high correlation with the power and loads such that a power or load assessment can be performed from a few hours or days of measurements.In the present study a blade-mounted five-hole pitot tube is used as the flow sensor as an alternative to the conventional approach, where the reference wind speed is either measured at a nearby met mast or on the nacelle using lidar technology or cup anemometers. From the flow sensor measurements, an accurate estimate of the wind speed at the rotor plane can be obtained. This wind speed is disturbed by the presence of the wind turbine, and it is therefore different from the free-flow wind speed. However, the recorded wind speed has a high correlation with the actual power production as well as the flap-wise loads as it is measured close to the blade where the aerodynamic forces are acting.Conventional power curves are based on at least 180 h of 10 min mean values, but using the blade-mounted flow sensor both the observation average time and the overall assessment time can potentially be shortened. The basis for this hypothesis is that the sensor is able to provide more observations with higher accuracy, as the sensor follows the rotation of the rotor and because of the high correlation between the flow at the blades and the power production. This is the research question addressed in this paper.The method is first tested using aeroelastic simulations where the dependence of the radial position and effect of multiple blade-mounted flow sensors are also investigated. Next the method is evaluated on the basis of full-scale measurements on a pitch-regulated, variable-speed 3.6 MW wind turbine.It is concluded that the wind speed derived from the blade-mounted flow sensor is highly correlated with the

  13. ALICE HLT high speed tracking on GPU

    CERN Document Server

    Gorbunov, Sergey; Aamodt, Kenneth; Alt, Torsten; Appelshauser, Harald; Arend, Andreas; Bach, Matthias; Becker, Bruce; Bottger, Stefan; Breitner, Timo; Busching, Henner; Chattopadhyay, Sukalyan; Cleymans, Jean; Cicalo, Corrado; Das, Indranil; Djuvsland, Oystein; Engel, Heiko; Erdal, Hege Austrheim; Fearick, Roger; Haaland, Oystein Senneset; Hille, Per Thomas; Kalcher, Sebastian; Kanaki, Kalliopi; Kebschull, Udo Wolfgang; Kisel, Ivan; Kretz, Matthias; Lara, Camillo; Lindal, Sven; Lindenstruth, Volker; Masoodi, Arshad Ahmad; Ovrebekk, Gaute; Panse, Ralf; Peschek, Jorg; Ploskon, Mateusz; Pocheptsov, Timur; Ram, Dinesh; Rascanu, Theodor; Richter, Matthias; Rohrich, Dieter; Ronchetti, Federico; Skaali, Bernhard; Smorholm, Olav; Stokkevag, Camilla; Steinbeck, Timm Morten; Szostak, Artur; Thader, Jochen; Tveter, Trine; Ullaland, Kjetil; Vilakazi, Zeblon; Weis, Robert; Yin, Zhong-Bao; Zelnicek, Pierre

    2011-01-01

    The on-line event reconstruction in ALICE is performed by the High Level Trigger, which should process up to 2000 events per second in proton-proton collisions and up to 300 central events per second in heavy-ion collisions, corresponding to an inp ut data stream of 30 GB/s. In order to fulfill the time requirements, a fast on-line tracker has been developed. The algorithm combines a Cellular Automaton method being used for a fast pattern recognition and the Kalman Filter method for fitting of found trajectories and for the final track selection. The tracker was adapted to run on Graphics Processing Units (GPU) using the NVIDIA Compute Unified Device Architecture (CUDA) framework. The implementation of the algorithm had to be adjusted at many points to allow for an efficient usage of the graphics cards. In particular, achieving a good overall workload for many processor cores, efficient transfer to and from the GPU, as well as optimized utilization of the different memories the GPU offers turned out to be cri...

  14. Local scattering property scales flow speed estimation in laser speckle contrast imaging

    International Nuclear Information System (INIS)

    Miao, Peng; Chao, Zhen; Feng, Shihan; Ji, Yuanyuan; Yu, Hang; Thakor, Nitish V; Li, Nan

    2015-01-01

    Laser speckle contrast imaging (LSCI) has been widely used in in vivo blood flow imaging. However, the effect of local scattering property (scattering coefficient µ s ) on blood flow speed estimation has not been well investigated. In this study, such an effect was quantified and involved in relation between speckle autocorrelation time τ c and flow speed v based on simulation flow experiments. For in vivo blood flow imaging, an improved estimation strategy was developed to eliminate the estimation bias due to the inhomogeneous distribution of the scattering property. Compared to traditional LSCI, a new estimation method significantly suppressed the imaging noise and improves the imaging contrast of vasculatures. Furthermore, the new method successfully captured the blood flow changes and vascular constriction patterns in rats’ cerebral cortex from normothermia to mild and moderate hypothermia. (letter)

  15. High speed motion-picture photography. Instrumentation and application

    International Nuclear Information System (INIS)

    Bertin-Maghit, G.; Delli, C.; Falgayrettes, M.

    1981-01-01

    Filming technology at 5,000 frames/second is presented in this paper for the determination of the volume and the expension speed of a gas bubble in water. The high speed 16 mm movie camera, fitted with ultra-wide angle lenses, is placed in front of a side light facing the bubble. Ten 60 ms fast flashes, released in succession, illuminate the bubble [fr

  16. High Speed Trimaran (HST) Seatrain Experiments, Model 5714

    Science.gov (United States)

    2013-12-01

    wave absorbing beach at the other. The carriage has electro-hydraulic drive and a regenerative braking system with a maximum carriage speed of 20...Carderock Division To: Commander, Naval Sea Systems Command (PMS3 85) Subj FORWARDING OF REPORT Encl: (1) NSWCCD-80-TR-2013/015, "High Speed Trimaran...and verify the system processes and capability. Your comments will be reviewed and are appreciated. JUDE F. BROWN By direction Copy to: NAVSEA

  17. Recent progress on high-speed optical transmission

    Directory of Open Access Journals (Sweden)

    Jianjun Yu

    2016-05-01

    Full Text Available The recently reported high spectral efficiency (SE and high-baud-rate signal transmission are all based on digital coherent optical communications and digital signal processing (DSP. DSP simplifies the reception of advanced modulation formats and also enables the major electrical and optical impairments to be processed and compensated in the digital domain, at the transmitter or receiver side. In this paper, we summarize the research progress on high-speed signal generation and detection and also show the progress on DSP for high-speed signal detection. We also report the latest progress on multi-core and multi-mode multiplexing.

  18. An ultra-high speed whole slide image viewing system.

    Science.gov (United States)

    Yagi, Yukako; Yoshioka, Shigeatsu; Kyusojin, Hiroshi; Onozato, Maristela; Mizutani, Yoichi; Osato, Kiyoshi; Yada, Hiroaki; Mark, Eugene J; Frosch, Matthew P; Louis, David N

    2012-01-01

    One of the goals for a Whole Slide Imaging (WSI) system is implementation in the clinical practice of pathology. One of the unresolved problems in accomplishing this goal is the speed of the entire process, i.e., from viewing the slides through making the final diagnosis. Most users are not satisfied with the correct viewing speeds of available systems. We have evaluated a new WSI viewing station and tool that focuses on speed. A prototype WSI viewer based on PlayStation®3 with wireless controllers was evaluated at the Department of Pathology at MGH for the following reasons: 1. For the simulation of signing-out cases; 2. Enabling discussion at a consensus conference; and 3. Use at slide seminars during a Continuing Medical Education course. Pathologists were being able to use the system comfortably after 0-15 min training. There were no complaints regarding speed. Most pathologists were satisfied with the functionality, usability and speed of the system. The most difficult situation was simulating diagnostic sign-out. The preliminary results of adapting the Sony PlayStation®3 (PS3®) as an ultra-high speed WSI viewing system were promising. The achieved speed is consistent with what would be needed to use WSI in daily practice.

  19. Nickel/Diamond Composite Coating Prepared by High Speed Electrodeposition

    Directory of Open Access Journals (Sweden)

    ZHANG Yan

    2016-10-01

    Full Text Available Nickel/diamond composite coatings were prepared on the basis of a new high speed electroplating bath. The influence of additives, plating parameters and diamond concentration on internal stress was investigated in order to find the solution to decrease the stress introduced by high current density; the micro morphology of the coatings were observed by SEM. The bath and depositing parameters were optimized that thick nickel/diamond composite coatings with low internal stress can be high speed electroplated with a high cathode current density of 30A/dm2. The results show that when plated with bath composition and parameters as follows: sodium dodecyl sulfate 0.5g/L, ammonium acetate 3g/L, sodium citrate 1.5g/L, diamond particles 30g/L; pH value 3-4, temperature 50℃, the composite coatings prepared in high speed have the lowest internal stress.

  20. Material requirements for the High Speed Civil Transport

    Science.gov (United States)

    Stephens, Joseph R.; Hecht, Ralph J.; Johnson, Andrew M.

    1993-01-01

    Under NASA-sponsored High Speed Research (HSR) programs, the materials and processing requirements have been identified for overcoming the environmental and economic barriers of the next generation High Speed Civil Transport (HSCT) propulsion system. The long (2 to 5 hours) supersonic cruise portion of the HSCT cycle will place additional durability requirements on all hot section engine components. Low emissions combustor designs will require high temperature ceramic matrix composite liners to meet an emission goal of less than 5g NO(x) per Kg fuel burned. Large axisymmetric and two-dimensional exhaust nozzle designs are now under development to meet or exceed FAR 36 Stage III noise requirements, and will require lightweight, high temperature metallic, intermetallic, and ceramic matrix composites to reduce nozzle weight and meet structural and acoustic component performance goals. This paper describes and discusses the turbomachinery, combustor, and exhaust nozzle requirements of the High Speed Civil Transport propulsion system.

  1. A study on the performance and internal flow characteristics of a very low specific speed centrifugal pump

    International Nuclear Information System (INIS)

    Choi, Young Do; Kurokawa, Junichi; Lee, Young Ho

    2005-01-01

    In the very low specific speed range (n s < 0.25, non-dimensional), the efficiency of centrifugal pump designed by a conventional method is very low in common. Therefore, positive-displacement pumps have long been used widely. Recently, since the centrifugal pumps are becoming higher in rotational speed and smaller in size, there experts to develop a new centrifugal pump with a high performance to replace the positive-displacement pumps. The purpose of this study is to investigate the internal flow characteristics of a very low specific speed centrifugal pump and to examine the effect of internal flow pattern on pump performance. The results show that the theoretical head definition of semi-open impeller should be revised by the consideration of high slip factor in the semi-open impeller, and the leakage flow through the tip clearance results in a large effect on the impeller internal flow. Strong reverse flow at the outlet of semi-open impeller reduces the absolute tangential velocity considerably, and the decreased absolute tangential velocity increases the slip factor with the reduction of theoretical head

  2. Honeybees' speed depends on dorsal as well as lateral, ventral and frontal optic flows.

    Directory of Open Access Journals (Sweden)

    Geoffrey Portelli

    Full Text Available Flying insects use the optic flow to navigate safely in unfamiliar environments, especially by adjusting their speed and their clearance from surrounding objects. It has not yet been established, however, which specific parts of the optical flow field insects use to control their speed. With a view to answering this question, freely flying honeybees were trained to fly along a specially designed tunnel including two successive tapering parts: the first part was tapered in the vertical plane and the second one, in the horizontal plane. The honeybees were found to adjust their speed on the basis of the optic flow they perceived not only in the lateral and ventral parts of their visual field, but also in the dorsal part. More specifically, the honeybees' speed varied monotonically, depending on the minimum cross-section of the tunnel, regardless of whether the narrowing occurred in the horizontal or vertical plane. The honeybees' speed decreased or increased whenever the minimum cross-section decreased or increased. In other words, the larger sum of the two opposite optic flows in the horizontal and vertical planes was kept practically constant thanks to the speed control performed by the honeybees upon encountering a narrowing of the tunnel. The previously described ALIS ("AutopiLot using an Insect-based vision System" model nicely matches the present behavioral findings. The ALIS model is based on a feedback control scheme that explains how honeybees may keep their speed proportional to the minimum local cross-section of a tunnel, based solely on optic flow processing, without any need for speedometers or rangefinders. The present behavioral findings suggest how flying insects may succeed in adjusting their speed in their complex foraging environments, while at the same time adjusting their distance not only from lateral and ventral objects but also from those located in their dorsal visual field.

  3. Basic Research into High-Speed Supercavitating Bodies

    National Research Council Canada - National Science Library

    Stinebring, David

    2001-01-01

    Critical technologies related to SCAT development, including cavitator hydrodynamics, control surface hydrodynamics, static pressure sensing, flow noise calculations and hydrodynamics modeling of high...

  4. Assessment of rural soundscapes with high-speed train noise.

    Science.gov (United States)

    Lee, Pyoung Jik; Hong, Joo Young; Jeon, Jin Yong

    2014-06-01

    In the present study, rural soundscapes with high-speed train noise were assessed through laboratory experiments. A total of ten sites with varying landscape metrics were chosen for audio-visual recording. The acoustical characteristics of the high-speed train noise were analyzed using various noise level indices. Landscape metrics such as the percentage of natural features (NF) and Shannon's diversity index (SHDI) were adopted to evaluate the landscape features of the ten sites. Laboratory experiments were then performed with 20 well-trained listeners to investigate the perception of high-speed train noise in rural areas. The experiments consisted of three parts: 1) visual-only condition, 2) audio-only condition, and 3) combined audio-visual condition. The results showed that subjects' preference for visual images was significantly related to NF, the number of land types, and the A-weighted equivalent sound pressure level (LAeq). In addition, the visual images significantly influenced the noise annoyance, and LAeq and NF were the dominant factors affecting the annoyance from high-speed train noise in the combined audio-visual condition. In addition, Zwicker's loudness (N) was highly correlated with the annoyance from high-speed train noise in both the audio-only and audio-visual conditions. © 2013.

  5. HDR 192Ir source speed measurements using a high speed video camera

    International Nuclear Information System (INIS)

    Fonseca, Gabriel P.; Viana, Rodrigo S. S.; Yoriyaz, Hélio; Podesta, Mark; Rubo, Rodrigo A.; Sales, Camila P. de; Reniers, Brigitte; Verhaegen, Frank

    2015-01-01

    Purpose: The dose delivered with a HDR 192 Ir afterloader can be separated into a dwell component, and a transit component resulting from the source movement. The transit component is directly dependent on the source speed profile and it is the goal of this study to measure accurate source speed profiles. Methods: A high speed video camera was used to record the movement of a 192 Ir source (Nucletron, an Elekta company, Stockholm, Sweden) for interdwell distances of 0.25–5 cm with dwell times of 0.1, 1, and 2 s. Transit dose distributions were calculated using a Monte Carlo code simulating the source movement. Results: The source stops at each dwell position oscillating around the desired position for a duration up to (0.026 ± 0.005) s. The source speed profile shows variations between 0 and 81 cm/s with average speed of ∼33 cm/s for most of the interdwell distances. The source stops for up to (0.005 ± 0.001) s at nonprogrammed positions in between two programmed dwell positions. The dwell time correction applied by the manufacturer compensates the transit dose between the dwell positions leading to a maximum overdose of 41 mGy for the considered cases and assuming an air-kerma strength of 48 000 U. The transit dose component is not uniformly distributed leading to over and underdoses, which is within 1.4% for commonly prescribed doses (3–10 Gy). Conclusions: The source maintains its speed even for the short interdwell distances. Dose variations due to the transit dose component are much lower than the prescribed treatment doses for brachytherapy, although transit dose component should be evaluated individually for clinical cases

  6. Energetic optimization of regenerative braking for high speed railway systems

    International Nuclear Information System (INIS)

    Frilli, Amedeo; Meli, Enrico; Nocciolini, Daniele; Pugi, Luca; Rindi, Andrea

    2016-01-01

    Highlights: • A model of longitudinal dynamics of the High-speed train ETR1000 is presented. • The model includes on board traction and braking subsystems. • Interactions between overhead line and power line are modelled. • The model is validated on real experimental data. • An energy storage strategy for a high-speed line is proposed. - Abstract: The current development trend in the railway field has led to an ever increasing interest for the energetic optimization of railway systems (especially considering the braking phases), with a strong attention to the mutual interactions between the loads represented by railway vehicles and the electrical infrastructure, including all the sub-systems related to distribution and smart energy management such as energy storage systems. In this research work, the authors developed an innovative coupled modelling approach suitable for the analysis of the energetic optimization of railway systems and based on the use of the new object oriented language Matlab-Simscape™, which presents several advantages with respect to conventional modelling tools. The proposed model has been validated considering an Italian Direct Current High-speed line and the High-speed train ETR 1000. Furthermore, the model has been used to perform an efficiency analysis, considering the use of energy storage devices. The results obtained with the developed model show that the use of energy recovery systems in high-speed railway can provide great opportunities of energy savings.

  7. High-speed railway signal trackside equipment patrol inspection system

    Science.gov (United States)

    Wu, Nan

    2018-03-01

    High-speed railway signal trackside equipment patrol inspection system comprehensively applies TDI (time delay integration), high-speed and highly responsive CMOS architecture, low illumination photosensitive technique, image data compression technique, machine vision technique and so on, installed on high-speed railway inspection train, and achieves the collection, management and analysis of the images of signal trackside equipment appearance while the train is running. The system will automatically filter out the signal trackside equipment images from a large number of the background image, and identify of the equipment changes by comparing the original image data. Combining with ledger data and train location information, the system accurately locate the trackside equipment, conscientiously guiding maintenance.

  8. Single-Photon Tracking for High-Speed Vision

    Directory of Open Access Journals (Sweden)

    Istvan Gyongy

    2018-01-01

    Full Text Available Quanta Imager Sensors provide photon detections at high frame rates, with negligible read-out noise, making them ideal for high-speed optical tracking. At the basic level of bit-planes or binary maps of photon detections, objects may present limited detail. However, through motion estimation and spatial reassignment of photon detections, the objects can be reconstructed with minimal motion artefacts. We here present the first demonstration of high-speed two-dimensional (2D tracking and reconstruction of rigid, planar objects with a Quanta Image Sensor, including a demonstration of depth-resolved tracking.

  9. Preliminary tests of a high speed vertical axis windmill model

    Energy Technology Data Exchange (ETDEWEB)

    South, P; Rangi, R S

    1971-01-01

    This report discusses a fixed-pitch vertical axis windmill that combines the inherent simplicity of this type of machine with a high aerodynamic efficiency and a high relative velocity. A three-bladed rotor was selected as the basic design, having constant chord symmetric airfoil blades configured in a catenary curve such that the rotor diameter is equal to the rotor height. In wind tunnel tests using a 30 inch scale model, it was found that once this rotor was given a very low rotational speed, it picked up speed and ran at a rotor tip velocity/wind speed ratio greater than 1. The number of blades was varied in the testing. A maximum power coefficient of 0.67 was achieved at 17 ft/s wind speed at a tip speed/wind speed ratio of 7.25 for a 2-bladed rotor. Increasing the number of blades above 3 did not result in higher power. The rotor could operate in gusts which double the mean wind velocity. Examination of Reynolds number effects, and taking into account the scale of the model, it was concluded that a full-scale windmill could run at lower velocity ratios than those predicted by the model tests, and that it could self-start under no-load conditions if the cut-in rpm are at least half the rpm for maximum power at the prevailing wind speed. Preliminary estimates show that a 15 ft diameter windmill of this design, designed to operate with a safety factor of 2.5 up to a maximum wind speed of 60 ft/s, would weigh ca 150 lb and could be marketed for ca $60.00, excluding the driven unit, if sufficient quantities were produced to make tooling costs negligible. Similarly, a 30 ft windmill would weigh ca 1000 lb and cost ca $400.00. 2 refs., 6 figs.

  10. Virtual Refrigerant Mass Flow and Power Sensors for Variable-Speed Compressors

    OpenAIRE

    Kim, Woohyun; Braun, James E.

    2012-01-01

    The use of variable-speed compressors in heat pumps and air conditioners has increased in recent years in order to improve comfort and energy efficiency. At the same time, there is a trend towards embedding more sensors in this type of equipment to facilitate real-time energy monitoring and diagnostics. Although compressor mass flow rate and power consumption are useful indices for performance monitoring and diagnostics, they are expensive to measure. The virtual variable-speed compressor sen...

  11. Noise in the passenger cars of high-speed trains.

    Science.gov (United States)

    Hong, Joo Young; Cha, Yongwon; Jeon, Jin Yong

    2015-12-01

    The aim of this study is to investigate the effects of both room acoustic conditions and spectral characteristics of noises on acoustic discomfort in a high-speed train's passenger car. Measurement of interior noises in a high-speed train was performed when the train was operating at speeds of 100 km/h and 300 km/h. Acoustic discomfort caused by interior noises was evaluated by paired comparison methods based on the variation of reverberation time (RT) in a passenger car and the spectral differences in interior noises. The effect of RT on acoustic discomfort was not significant, whereas acoustic discomfort significantly varied depending on spectral differences in noise. Acoustic discomfort increased with increment of the sound pressure level (SPL) ratio at high frequencies, and variation in high-frequency noise components were described using sharpness. Just noticeable differences of SPL with low- and high-frequency components were determined to be 3.7 and 2.9 dB, respectively. This indicates that subjects were more sensitive to differences in SPLs at the high-frequency range than differences at the low-frequency range. These results support that, for interior noises, reduction in SPLs at high frequencies would significantly contribute to improved acoustic quality in passenger cars of high-speed trains.

  12. Adaptations to speed endurance training in highly trained soccer players

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Fiorenza, Matteo; Lund, Anders

    2016-01-01

    PURPOSE: The present study examined whether a period of additional speed endurance training would improve intense intermittent exercise performance in highly trained soccer players during the season and whether the training changed aerobic metabolism and the level of oxidative enzymes in type I...... and II muscle fibers. METHODS: During the last nine weeks of the season, thirteen semi-professional soccer players performed additional speed endurance training sessions consisting of 2-3 sets of 8 - 10 repetitions of 30 m sprints with 10 s of passive recovery (SET). Before and after SET, subjects...... in type I and II fibers did not change. CONCLUSION: In highly trained soccer players, additional speed endurance training is associated with an improved ability to perform repeated high-intensity work. To what extent the training-induced changes in V˙O2 kinetics and mechanical efficiency in type I fibers...

  13. Design and Checkout of a High Speed Research Nozzle Evaluation Rig

    Science.gov (United States)

    Castner, Raymond S.; Wolter, John D.

    1997-01-01

    The High Flow Jet Exit Rig (HFJER) was designed to provide simulated mixed flow turbojet engine exhaust for one- seventh scale models of advanced High Speed Research test nozzles. The new rig was designed to be used at NASA Lewis Research Center in the Nozzle Acoustic Test Rig and the 8x6 Supersonic Wind Tunnel. Capabilities were also designed to collect nozzle thrust measurement, aerodynamic measurements, and acoustic measurements when installed at the Nozzle Acoustic Test Rig. Simulated engine exhaust can be supplied from a high pressure air source at 33 pounds of air per second at 530 degrees Rankine and nozzle pressure ratios of 4.0. In addition, a combustion unit was designed from a J-58 aircraft engine burner to provide 20 pounds of air per second at 2000 degrees Rankine, also at nozzle pressure ratios of 4.0. These airflow capacities were designed to test High Speed Research nozzles with exhaust areas from eighteen square inches to twenty-two square inches. Nozzle inlet flow measurement is available through pressure and temperature sensors installed in the rig. Research instrumentation on High Speed Research nozzles is available with a maximum of 200 individual pressure and 100 individual temperature measurements. Checkout testing was performed in May 1997 with a 22 square inch ASME long radius flow nozzle. Checkout test results will be summarized and compared to the stated design goals.

  14. STATUS REPORT ON DEVELOPMENT OF A HIGH-SPEED HIGH-INTENSITY MOLECULAR BEAM

    Energy Technology Data Exchange (ETDEWEB)

    Knuth, Eldon L.

    1963-07-15

    Status of a high-speed high-intensity molecular beam under development is described. Bases for designs of the several components are presented. Using an arc-heated source and a hypersonic jet, molecular energies exceeding 1 ev and beam intensities of the order of 10/sup 16/ molecules/ cm/sup 2/ sec are anticipated. A two-disk beam chopper and speed selector provides a means for analyzing the speed distribution in the generated beam, for chopping the beam into bursts of nearly monoenergetic molecules suitable for scattering studies using the time-of-flight technique, and for modulating the beam in order to facilitate detection. A through-flow ionization detector possesses the versatility required for scattering studies using the time-of-flight technique. A sorption pump and a turbo pump serve as central components of alternative pumping systems for the collimating chamber. Using the arc-heated source, the converging nozzle, the conduction-radiation-cooled skimmer, the turbo pump (turning at 3400 rpm), the chopperselector (acting only as a chopper), and the detector, an arc-heated beam is generated and detected. (auth)

  15. Grain Flow at High Stresses

    Science.gov (United States)

    McSaveney, M. J.

    2015-12-01

    The transport mechanism of rapid long-runout rock avalanches was a hotly debated topic when I came on the scene in 1967. So how come it is still debated today? My explanation is that it is the expected outcome of peer review, poor comprehension, and technological advances outpacing intellectual advances. Why think about the problem when we can model it! So let us think about the problem. Shreve thought that rock avalanches fell upon and trapped a layer of air. What physics was he thinking about? It is how feathers and tissue papers fall. When my rock avalanches fly, they fly like unlubricated bricks using the physics of projectiles and ballistics. But the main transport mechanism is not flight. The dominant impression from watching a rock avalanche in motion is of fluid flow, as Heim described it in 1882. A rock avalanche is a very large grain flow. Bagnold studied dispersive grain flows, but why should one assume that rock avalanches are dispersive grain flows as many do. The more common grain flow type is a dense grain flow and rock avalanches are dense grain flows in which the weight can and does generate very high stresses at grain contacts. Brittle rock deforms elastically up to its compressive strength, whereupon it breaks, releasing elastic strain as transient elastic strain (seismic energy to a seismologist, acoustic energy to a physicist). Melosh and others have shown that acoustic energy can fluidize a grain mass. There is no exotic physics behind grain flow at high stress. When grains break, the released elastic strain has to go somewhere, and it goes somewhere principally by transmission though grain contacts. Depending on the state of stress at the grain contact, the contact will pass the stress or will slip at conventional values of Coulomb friction. Enough thinking! A physical model of the entire process is too big for any laboratory. So whose numerical model will do it?

  16. Stability control for high speed tracked unmanned vehicles

    Science.gov (United States)

    Pape, Olivier; Morillon, Joel G.; Houbloup, Philippe; Leveque, Stephane; Fialaire, Cecile; Gauthier, Thierry; Ropars, Patrice

    2005-05-01

    The French Military Robotic Study Program (introduced in Aerosense 2003), sponsored by the French Defense Procurement Agency and managed by Thales as the prime contractor, focuses on about 15 robotic themes which can provide an immediate "operational add-on value". The paper details the "automatic speed adjustment" behavior (named SYR4), developed by Giat Industries Company, which main goal is to secure the teleoperated mobility of high speed tracked vehicles on rough grounds; more precisely, the validated low level behavior continuously adjusts the vehicle speed taking into account the teleperator wish AND the maximum speed that the vehicle can manage safely according to the commanded radius of curvature. The algorithm is based on a realistic physical model of the ground-tracks relation, taking into account many vehicle and ground parameters (such as ground adherence and dynamic specificities of tracked vehicles). It also deals with the teleoperator-machine interface, providing a balanced strategy between both extreme behaviors: a) maximum speed reduction before initiating the commanded curve; b) executing the minimum possible radius without decreasing the commanded speed. The paper presents the results got from the military acceptance tests performed on tracked SYRANO vehicle (French Operational Demonstrator).

  17. Comprehensive surface treatment of high-speed steel tool

    Science.gov (United States)

    Fedorov, Sergey V.; Aleshin, Sergey V.; Swe, Min Htet; Abdirova, Raushan D.; Kapitanov, Alexey V.; Egorov, Sergey B.

    2018-03-01

    One of the promising directions of hardening of high-speed steel tool is the creation on their surface of the layered structures with the gradient of physic-chemical properties between the wear-resistant coatings to the base material. Among the methods of such surface modification, a special process takes place based on the use of pulsed high-intensity charged particle beams. The high speed of heating and cooling allows structural-phase transformations in the surface layer, which cannot be realized in a stationary mode. The treatment was conducted in a RITM-SP unit, which constitutes a combination of a source of low-energy high-current electron beams "RITM" and two magnetron spraying systems on a single vacuum chamber. The unit enables deposition of films on the surface of the desired product and subsequent liquid-phase mixing of materials of the film and the substrate by an intense pulse electron beam. The article discusses features of the structure of the subsurface layer of high-speed steel M2, modified by surface alloying of a low-energy high-current electron beam, and its effect on the wear resistance of the tool when dry cutting hard to machine Nickel alloy. A significant decrease of intensity of wear of high-speed steel with combined treatment happens due to the displacement of the zone of wear and decrease the radius of rounding of the cutting edge because of changes in conditions of interaction with the material being treated.

  18. Generating pulsatility by pump speed modulation with continuous-flow total artificial heart in awake calves.

    Science.gov (United States)

    Fukamachi, Kiyotaka; Karimov, Jamshid H; Sunagawa, Gengo; Horvath, David J; Byram, Nicole; Kuban, Barry D; Dessoffy, Raymond; Sale, Shiva; Golding, Leonard A R; Moazami, Nader

    2017-12-01

    The purpose of this study was to evaluate the effects of sinusoidal pump speed modulation of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) on hemodynamics and pump flow in an awake chronic calf model. The sinusoidal pump speed modulations, performed on the day of elective sacrifice, were set at ±15 and ± 25% of mean pump speed at 80 bpm in four awake calves with a CFTAH. The systemic and pulmonary arterial pulse pressures increased to 12.0 and 12.3 mmHg (±15% modulation) and to 15.9 and 15.7 mmHg (±25% modulation), respectively. The pulsatility index and surplus hemodynamic energy significantly increased, respectively, to 1.05 and 1346 ergs/cm at ±15% speed modulation and to 1.51 and 3381 ergs/cm at ±25% speed modulation. This study showed that it is feasible to generate pressure pulsatility with pump speed modulation; the platform is suitable for evaluating the physiologic impact of pulsatility and allows determination of the best speed modulations in terms of magnitude, frequency, and profiles.

  19. High-speed measurement of firearm primer blast waves

    OpenAIRE

    Courtney, Michael; Daviscourt, Joshua; Eng, Jonathan; Courtney, Amy

    2012-01-01

    This article describes a method and results for direct high-speed measurements of firearm primer blast waves employing a high-speed pressure transducer located at the muzzle to record the blast pressure wave produced by primer ignition. Key findings are: 1) Most of the lead styphnate based primer models tested show 5.2-11.3% standard deviation in the magnitudes of their peak pressure. 2) In contrast, lead-free diazodinitrophenol (DDNP) based primers had standard deviations of the peak blast p...

  20. High-speed photodetectors in optical communication system

    Science.gov (United States)

    Zhao, Zeping; Liu, Jianguo; Liu, Yu; Zhu, Ninghua

    2017-12-01

    This paper presents a review and discussion for high-speed photodetectors and their applications on optical communications and microwave photonics. A detailed and comprehensive demonstration of high-speed photodetectors from development history, research hotspots to packaging technologies is provided to the best of our knowledge. A few typical applications based on photodetectors are also illustrated, such as free-space optical communications, radio over fiber and millimeter terahertz signal generation systems. Project supported by the Preeminence Youth Fund of China (No. 61625504).

  1. Miniature high speed compressor having embedded permanent magnet motor

    Science.gov (United States)

    Zhou, Lei (Inventor); Zheng, Liping (Inventor); Chow, Louis (Inventor); Kapat, Jayanta S. (Inventor); Wu, Thomas X. (Inventor); Kota, Krishna M. (Inventor); Li, Xiaoyi (Inventor); Acharya, Dipjyoti (Inventor)

    2011-01-01

    A high speed centrifugal compressor for compressing fluids includes a permanent magnet synchronous motor (PMSM) having a hollow shaft, the being supported on its ends by ball bearing supports. A permanent magnet core is embedded inside the shaft. A stator with a winding is located radially outward of the shaft. The PMSM includes a rotor including at least one impeller secured to the shaft or integrated with the shaft as a single piece. The rotor is a high rigidity rotor providing a bending mode speed of at least 100,000 RPM which advantageously permits implementation of relatively low-cost ball bearing supports.

  2. Magneto-optical system for high speed real time imaging

    Science.gov (United States)

    Baziljevich, M.; Barness, D.; Sinvani, M.; Perel, E.; Shaulov, A.; Yeshurun, Y.

    2012-08-01

    A new magneto-optical system has been developed to expand the range of high speed real time magneto-optical imaging. A special source for the external magnetic field has also been designed, using a pump solenoid to rapidly excite the field coil. Together with careful modifications of the cryostat, to reduce eddy currents, ramping rates reaching 3000 T/s have been achieved. Using a powerful laser as the light source, a custom designed optical assembly, and a high speed digital camera, real time imaging rates up to 30 000 frames per seconds have been demonstrated.

  3. NASA low-speed centrifugal compressor for 3-D viscous code assessment and fundamental flow physics research

    Science.gov (United States)

    Hathaway, M. D.; Wood, J. R.; Wasserbauer, C. A.

    1991-01-01

    A low speed centrifugal compressor facility recently built by the NASA Lewis Research Center is described. The purpose of this facility is to obtain detailed flow field measurements for computational fluid dynamic code assessment and flow physics modeling in support of Army and NASA efforts to advance small gas turbine engine technology. The facility is heavily instrumented with pressure and temperature probes, both in the stationary and rotating frames of reference, and has provisions for flow visualization and laser velocimetry. The facility will accommodate rotational speeds to 2400 rpm and is rated at pressures to 1.25 atm. The initial compressor stage being tested is geometrically and dynamically representative of modern high-performance centrifugal compressor stages with the exception of Mach number levels. Preliminary experimental investigations of inlet and exit flow uniformly and measurement repeatability are presented. These results demonstrate the high quality of the data which may be expected from this facility. The significance of synergism between computational fluid dynamic analysis and experimentation throughout the development of the low speed centrifugal compressor facility is demonstrated.

  4. High Reynolds number flows using liquid and gaseous helium

    International Nuclear Information System (INIS)

    Donnelly, R.J.

    1991-01-01

    Consideration is given to liquid and gaseous helium as test fluids, high Reynolds number test requirements in low speed aerodynamics, the measurement of subsonic flow around an appended body of revolution at cryogenic conditions in the NTF, water tunnels, flow visualization, the six component magnetic suspension system for wind tunnel testing, and recent aerodynamic measurements with magnetic suspension systems. Attention is also given to application of a flow visualization technique to a superflow experiment, experimental investigations of He II flows at high Reynolds numbers, a study of homogeneous turbulence in superfluid helium, and thermal convection in liquid helium

  5. Feature Tracking for High Speed AFM Imaging of Biopolymers.

    Science.gov (United States)

    Hartman, Brett; Andersson, Sean B

    2018-03-31

    The scanning speed of atomic force microscopes continues to advance with some current commercial microscopes achieving on the order of one frame per second and at least one reaching 10 frames per second. Despite the success of these instruments, even higher frame rates are needed with scan ranges larger than are currently achievable. Moreover, there is a significant installed base of slower instruments that would benefit from algorithmic approaches to increasing their frame rate without requiring significant hardware modifications. In this paper, we present an experimental demonstration of high speed scanning on an existing, non-high speed instrument, through the use of a feedback-based, feature-tracking algorithm that reduces imaging time by focusing on features of interest to reduce the total imaging area. Experiments on both circular and square gratings, as well as silicon steps and DNA strands show a reduction in imaging time by a factor of 3-12 over raster scanning, depending on the parameters chosen.

  6. High flow ceramic pot filters

    NARCIS (Netherlands)

    van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

    2017-01-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more

  7. A High-Speed Design of Montgomery Multiplier

    Science.gov (United States)

    Fan, Yibo; Ikenaga, Takeshi; Goto, Satoshi

    With the increase of key length used in public cryptographic algorithms such as RSA and ECC, the speed of Montgomery multiplication becomes a bottleneck. This paper proposes a high speed design of Montgomery multiplier. Firstly, a modified scalable high-radix Montgomery algorithm is proposed to reduce critical path. Secondly, a high-radix clock-saving dataflow is proposed to support high-radix operation and one clock cycle delay in dataflow. Finally, a hardware-reused architecture is proposed to reduce the hardware cost and a parallel radix-16 design of data path is proposed to accelerate the speed. By using HHNEC 0.25μm standard cell library, the implementation results show that the total cost of Montgomery multiplier is 130 KGates, the clock frequency is 180MHz and the throughput of 1024-bit RSA encryption is 352kbps. This design is suitable to be used in high speed RSA or ECC encryption/decryption. As a scalable design, it supports any key-length encryption/decryption up to the size of on-chip memory.

  8. Compression cracking of plastic spheres: a high speed photography study

    International Nuclear Information System (INIS)

    Majzoub, R.; Chaudhri, M.M.

    1999-01-01

    Failure of brittle spheres under compressive loading, both quasi static and dynamic, is a technologically important problem. However, so far, neither the stress state in a loaded nor the failure process in understood clearly. In fact, because the process of the failure of a loaded sphere is very rapid, it has not been possible to follow it when making static observations. We have, therefore, carried out a high-speed photographic study using framing rates of up to 200,000 frames per second to follow the sequence of events when polished 12.7 mm diameter spheres of acrylic resin are fragmented using a low-velocity impact apparatus. The latter consist of a 5.7 kg hammer, which is allowed to drop on to the test sphere from a height of 1.3 m and the entire event of impact and ensuing fracture is photographed with a rotating mirror camera (C-4). Form numerous impact experiments it has been found that as the impact load increases gradually, plastic flow and flattering of the sphere occurs at the contact region. The size of the flattened region continuous to grow with increasing impact load and when this region becomes sufficiently large, usually one or two cracks initiate at the periphery of the contact rather than in the bulk of the sphere. The surface cracks then grow into the bulk of the sphere at velocities in the range of 600-800 m s/sup -1/. It is interesting to note these crack velocities are the maximum observed velocities in this material, but these are only approx. 0.8 of the Rayleigh wave velocity, which is the theoretically predicted maximum crack velocity in brittle materials. It is argued that in order to cause the catastrophic failure of a solid sphere, it is necessary to cause plasticity in it which then leads to the generation of tensile hoop stresses at the circle of contact between the sphere and platen. (author)

  9. High-speed imaging of explosive eruptions: applications and perspectives

    Science.gov (United States)

    Taddeucci, Jacopo; Scarlato, Piergiorgio; Gaudin, Damien; Capponi, Antonio; Alatorre-Ibarguengoitia, Miguel-Angel; Moroni, Monica

    2013-04-01

    Explosive eruptions, being by definition highly dynamic over short time scales, necessarily call for observational systems capable of relatively high sampling rates. "Traditional" tools, like as seismic and acoustic networks, have recently been joined by Doppler radar and electric sensors. Recent developments in high-speed camera systems now allow direct visual information of eruptions to be obtained with a spatial and temporal resolution suitable for the analysis of several key eruption processes. Here we summarize the methods employed to gather and process high-speed videos of explosive eruptions, and provide an overview of the several applications of these new type of data in understanding different aspects of explosive volcanism. Our most recent set up for high-speed imaging of explosive eruptions (FAMoUS - FAst, MUltiparametric Set-up,) includes: 1) a monochrome high speed camera, capable of 500 frames per second (fps) at high-definition (1280x1024 pixel) resolution and up to 200000 fps at reduced resolution; 2) a thermal camera capable of 50-200 fps at 480-120x640 pixel resolution; and 3) two acoustic to infrasonic sensors. All instruments are time-synchronized via a data logging system, a hand- or software-operated trigger, and via GPS, allowing signals from other instruments or networks to be directly recorded by the same logging unit or to be readily synchronized for comparison. FAMoUS weights less than 20 kg, easily fits into four, hand-luggage-sized backpacks, and can be deployed in less than 20' (and removed in less than 2', if needed). So far, explosive eruptions have been recorded in high-speed at several active volcanoes, including Fuego and Santiaguito (Guatemala), Stromboli (Italy), Yasur (Vanuatu), and Eyjafiallajokull (Iceland). Image processing and analysis from these eruptions helped illuminate several eruptive processes, including: 1) Pyroclasts ejection. High-speed videos reveal multiple, discrete ejection pulses within a single Strombolian

  10. The influence of air flow speed on fire propagation in object

    Directory of Open Access Journals (Sweden)

    Jevtić Radoje

    2015-01-01

    Full Text Available Fire presents the process of the uncontrolled combustion that makes material damage and endangers human lives. It is important to know the factors that fire depends on for success projecting and realization of fire protection systems. One of such factors is different air flow that could be presented as wind, draft and the like. The simulation of different air flow speeds and its influences on fire propagation in object were analyzed in this paper.

  11. High-speed photography application to pulsed hot plasma investigation

    International Nuclear Information System (INIS)

    Borov'etskij, M.; Koz'yarkevich, V.; Skrzhechanovskij, V.; Socha, R.

    1986-01-01

    Plasma focus is investigated using an electron-optical chamber for high-speed photography (KSK-1). Experimental devices for studying dynamics and structure of a plasma layer in the chosen interval, recording plasma spectra with time resolution as well as for studying the dynamics and structure of a plasma layer by Schlieren- and shadow methods are briefly described. Experimental results are presented

  12. Modelling Of Residual Stresses Induced By High Speed Milling Process

    International Nuclear Information System (INIS)

    Desmaison, Olivier; Mocellin, Katia; Jardin, Nicolas

    2011-01-01

    Maintenance processes used in heavy industries often include high speed milling operations. The reliability of the post-process material state has to be studied. Numerical simulation appears to be a very interesting way to supply an efficient residual stresses (RS) distribution prediction.Because the adiabatic shear band and the serrated chip shaping are features of the austenitic stainless steel high speed machining, a 2D high speed orthogonal cutting model is briefly presented. This finite element model, developed on Forge registered software, is based on data taken from Outeiro and al.'s paper [1]. A new behaviour law fully coupling Johnson-Cook's constitutive law and Latham and Cockcroft's damage model is detailed in this paper. It ensures results that fit those found in literature.Then, the numerical tools used on the 2D model are integrated to a 3D high speed milling model. Residual stresses distribution is analysed, on the surface and into the depth of the material. Various revolutions and passes of the two teeth hemispheric mill on the workpiece are simulated. Thus the sensitivity of the residual stresses generation to the cutting conditions can be discussed. In order to validate the 3D model, a comparison of the cutting forces measured by EDF R and D to those given by numerical simulations is achieved.

  13. Intel Legend and CERN would build up high speed Internet

    CERN Multimedia

    2002-01-01

    Intel, Legend and China Education and Research Network jointly announced on the 25th of April that they will be cooperating with each other to build up the new generation high speed internet, over the next three years (1/2 page).

  14. Visualization of Projectile Flying at High Speed in Dusty Atmosphere

    Science.gov (United States)

    Masaki, Chihiro; Watanabe, Yasumasa; Suzuki, Kojiro

    2017-10-01

    Considering a spacecraft that encounters particle-laden environment, such as dust particles flying up over the regolith by the jet of the landing thruster, high-speed flight of a projectile in such environment was experimentally simulated by using the ballistic range. At high-speed collision of particles on the projectile surface, they may be reflected with cracking into smaller pieces. On the other hand, the projectile surface will be damaged by the collision. To obtain the fundamental characteristics of such complicated phenomena, a projectile was launched at the velocity up to 400 m/s and the collective behaviour of particles around projectile was observed by the high-speed camera. To eliminate the effect of the gas-particle interaction and to focus on only the effect of the interaction between the particles and the projectile's surface, the test chamber pressure was evacuated down to 30 Pa. The particles about 400μm diameter were scattered and formed a sheet of particles in the test chamber by using two-dimensional funnel with a narrow slit. The projectile was launched into the particle sheet in the tangential direction, and the high-speed camera captured both projectile and particle motions. From the movie, the interaction between the projectile and particle sheet was clarified.

  15. Soliton-based ultra-high speed optical communications

    Indian Academy of Sciences (India)

    All these facts are the outcome of research on optical solitons in fibers in spite of the fact that the commonly used RZ format is not always called a soliton format. The overview presented here attempts to incorporate the role of soliton-based communications research in present day ultra-high speed communications.

  16. The impact of high speed rail on airport competition

    NARCIS (Netherlands)

    Terpstra, I.; Lijesen, M.G.

    2015-01-01

    We study the effects of introducing a high speed train connection on competition between airports, focusing on the new HST-link between Amsterdam and Brussels. We conduct a detailed analysis regarding the airport choice of passengers living in the Netherlands, Belgium, Luxembourg, Northern France

  17. A High-Speed Train Operation Plan Inspection Simulation Model

    Directory of Open Access Journals (Sweden)

    Yang Rui

    2018-01-01

    Full Text Available We developed a train operation simulation tool to inspect a train operation plan. In applying an improved Petri Net, the train was regarded as a token, and the line and station were regarded as places, respectively, in accordance with the high-speed train operation characteristics and network function. Location change and running information transfer of the high-speed train were realized by customizing a variety of transitions. The model was built based on the concept of component combination, considering the random disturbance in the process of train running. The simulation framework can be generated quickly and the system operation can be completed according to the different test requirements and the required network data. We tested the simulation tool when used for the real-world Wuhan to Guangzhou high-speed line. The results showed that the proposed model can be developed, the simulation results basically coincide with the objective reality, and it can not only test the feasibility of the high-speed train operation plan, but also be used as a support model to develop the simulation platform with more capabilities.

  18. Research in high speed fiber optics local area networks

    Science.gov (United States)

    Tobagi, F. A.

    1986-01-01

    The design of high speed local area networks (HSLAN) for communication among distributed devices requires solving problems in three areas: the network medium and its topology, the medium access control, and the network interface. Considerable progress was already made in the first two areas. Accomplishments are divided into two groups according to their theoretical or experimental nature. A brief summary is given.

  19. APPLICATION OF POWDER HIGH-SPEED STEEL AS ANTIFRICTION MATERIAL

    Directory of Open Access Journals (Sweden)

    M. Beznak

    2011-01-01

    Full Text Available The influence of disulphide molybdenum additives on antifriction characteristics of powder high-speed steel produced by means of hot hydrostatic pressing is investigated. It is shown that disulphide molybdenum additives promote the decrease of coefficient of friction and temperature in hearth of friction as a result the increase of wear resistance of steel.

  20. Towards a high-speed quantum random number generator

    Science.gov (United States)

    Stucki, Damien; Burri, Samuel; Charbon, Edoardo; Chunnilall, Christopher; Meneghetti, Alessio; Regazzoni, Francesco

    2013-10-01

    Randomness is of fundamental importance in various fields, such as cryptography, numerical simulations, or the gaming industry. Quantum physics, which is fundamentally probabilistic, is the best option for a physical random number generator. In this article, we will present the work carried out in various projects in the context of the development of a commercial and certified high speed random number generator.

  1. Bottom Raking Damage to High-Speed Craft

    DEFF Research Database (Denmark)

    Simonsen, Bo Cerup

    1998-01-01

    This paper presents a comparative study of the raking damage to high speed craft (HSC) and conventional ships. The analysis is based on a detailed theoretical model for the raking resistance of an assembled ship bottom structure and on the idea that the impact conditions for various ship types have...

  2. Radiation response of high speed CMOS integrated circuits

    International Nuclear Information System (INIS)

    Yue, H.; Davison, D.; Jennings, R.F.; Lothongkam, P.; Rinerson, D.; Wyland, D.

    1987-01-01

    This paper studies the total dose and dose rate radiation response of the FCT family of high speed CMOS integrated circuits. Data taken on the devices is used to establish the dominant failure modes, and this data is further analyzed using one-sided tolerance factors for normal distribution statistical analysis

  3. High-Frequency Technical Trading: The Importance of Speed

    NARCIS (Netherlands)

    M.L. Scholtus (Martin); D.J.C. van Dijk (Dick)

    2012-01-01

    textabstractThis paper investigates the importance of speed for technical trading rule performance for three highly liquid ETFs listed on NASDAQ over the period January 6, 2009 up to September 30, 2009. In addition we examine the characteristics of market activity over the day and within subperiods

  4. Characterising argon-bomb balloons for high-speed photography

    CSIR Research Space (South Africa)

    Olivier, M

    2013-08-01

    Full Text Available A method to optimise the geometry, explosive charge mass and volume of an argon bomb for specific lighting requirements has been proposed. The method is specifically aimed at applications that require photographic diagnostics with ultra-high speed...

  5. High-Speed Railways and Urban Networks in China

    NARCIS (Netherlands)

    Yang, Haoran

    2018-01-01

    Worldwide, High-Speed Railway (HSR) networks have been developed intensely over the last few decades, such as Tokyo-Osaka, the first HSR corridor in Japan, the TGV in France and the ICE in Germany. HSR has also experienced exponential growth in China so that currently China’s HSR networks are the

  6. A data-acquisition system for high speed linear CCD

    International Nuclear Information System (INIS)

    Liu Zhiyan; Chen Xiangcai; Jiang Xiaoshan; Zhang Hongyu; Liang Zhongwang; Xiang Haisheng; Hu Jun

    2010-01-01

    A data-acquisition system for high speed linear CCD (Charge Coupled device) is mainly introduced. The optical fiber transmission technology is used. The data is sent to PC through USB or PCI interface. The construction of the system, the design of the PCI interface hardware, software design and the design of the control program running on host computer are also introduced. (authors)

  7. Time-interleaved high-speed D/A converters

    NARCIS (Netherlands)

    Olieman, E.

    2016-01-01

    This thesis is on power efficient very high-speed digital-to-analog converters (DACs) in CMOS technology, intended to generate signals from DC to RF. Components in RF signal chains are nowadays often moved from the analog domain to the digital domain. This allows for more flexibility and better

  8. High speed electro optic polymer micro-ringresonator

    NARCIS (Netherlands)

    Leinse, Arne; Diemeer, Mart; Driessen, A.

    2004-01-01

    An electro-optic polymer micro-ring resonator for high speed modulation was designed, realized and characterized. The design of layer-stack and electrodes was done such that modulation frequencies up till 1 GHz should be possible. The device consists of a ridge waveguide, defined in a negative

  9. A high-speed interconnect network using ternary logic

    DEFF Research Database (Denmark)

    Madsen, Jens Kargaard; Long, S. I.

    1995-01-01

    This paper describes the design and implementation of a high-speed interconnect network (ICN) for a multiprocessor system using ternary logic. By using ternary logic and a fast point-to-point communication technique called STARI (Self-Timed At Receiver's Input), the communication between...

  10. Cutting force model for high speed machining process

    International Nuclear Information System (INIS)

    Haber, R. E.; Jimenez, J. E.; Jimenez, A.; Lopez-Coronado, J.

    2004-01-01

    This paper presents cutting force-based models able to describe a high speed machining process. The model considers the cutting force as output variable, essential for the physical processes that are taking place in high speed machining. Moreover, this paper shows the mathematical development to derive the integral-differential equations, and the algorithms implemented in MATLAB to predict the cutting force in real time MATLAB is a software tool for doing numerical computations with matrices and vectors. It can also display information graphically and includes many toolboxes for several research and applications areas. Two end mill shapes are considered (i. e. cylindrical and ball end mill) for real-time implementation of the developed algorithms. the developed models are validated in slot milling operations. The results corroborate the importance of the cutting force variable for predicting tool wear in high speed machining operations. The developed models are the starting point for future work related with vibration analysis, process stability and dimensional surface finish in high speed machining processes. (Author) 19 refs

  11. Optimum Design of High Speed Prop-Rotors

    Science.gov (United States)

    Chattopadhyay, Aditi

    1992-01-01

    The objective of this research is to develop optimization procedures to provide design trends in high speed prop-rotors. The necessary disciplinary couplings are all considered within a closed loop optimization process. The procedures involve the consideration of blade aeroelastic, aerodynamic performance, structural and dynamic design requirements. Further, since the design involves consideration of several different objectives, multiobjective function formulation techniques are developed.

  12. Design of a high speed rotating mechanical shutter

    International Nuclear Information System (INIS)

    Stowers, I.F.; Merritt, B.T.; McFann, C.B.

    1979-01-01

    A high-speed rotating shutter was designed to operate in a 10 -6 Torr vacuum at the optical focus of a laser spatial filter. The shutter is basically a wheel, with a single 3 x 10-mm slot at the perimeter, which rotates with a peripheral speed of 1 km/s. The motor to drive the rotating wheel is magnetically suspended and synchronously wound. The wheel achieves a 4 μs opening time and a timing accuracy of better than 0.2 μs

  13. Error mapping of high-speed AFM systems

    Science.gov (United States)

    Klapetek, Petr; Picco, Loren; Payton, Oliver; Yacoot, Andrew; Miles, Mervyn

    2013-02-01

    In recent years, there have been several advances in the development of high-speed atomic force microscopes (HSAFMs) to obtain images with nanometre vertical and lateral resolution at frame rates in excess of 1 fps. To date, these instruments are lacking in metrology for their lateral scan axes; however, by imaging a series of two-dimensional lateral calibration standards, it has been possible to obtain information about the errors associated with these HSAFM scan axes. Results from initial measurements are presented in this paper and show that the scan speed needs to be taken into account when performing a calibration as it can lead to positioning errors of up to 3%.

  14. CERNET - A high-speed packet-switching network

    International Nuclear Information System (INIS)

    Gerard, J.M.

    1981-01-01

    A general mesh-structured high-speed computer network has been designed and built. This network provides communication between any pair of connected user computers over distances of upto 6 km and at line speeds of 1 to 5 Mbit/second. The network is composed of a communication subnet providing a datagram service, complemented by tasks in the connected machines to implement an end-to-end logical link protocol. Details are given of the overall structure as well as the specific modules of which the system is composed. (orig.)

  15. The large scale and long term evolution of the solar wind speed distribution and high speed streams

    International Nuclear Information System (INIS)

    Intriligator, D.S.

    1977-01-01

    The spatial and temporal evolution of the solar wind speed distribution and of high speed streams in the solar wind are examined. Comparisons of the solar wind streaming speeds measured at Earth, Pioneer 11, and Pioneer 10 indicate that between 1 AU and 6.4 AU the solar wind speed distributions are narrower (i.e. the 95% value minus the 5% value of the solar wind streaming speed is less) at extended heliocentric distances. These observations are consistent with one exchange of momentum in the solar wind between high speed streams and low speed streams as they propagate outward from the Sun. Analyses of solar wind observations at 1 AU from mid 1964 through 1973 confirm the earlier results reported by Intriligator (1974) that there are statistically significant variations in the solar wind in 1968 and 1969, years of solar maximum. High speed stream parameters show that the number of high speed streams in the solar wind in 1968 and 1969 is considerably more than the predicted yearly average, and in 1965 and 1972 less. Histograms of solar wind speed from 1964 through 1973 indicate that in 1968 there was the highest percentage of elevated solar wind speeds and in 1965 and 1972 the lowest. Studies by others also confirm these results although the respective authors did not indicate this fact. The duration of the streams and the histograms for 1973 imply a shifting in the primary stream source. (Auth.)

  16. Ultra High-Speed Radio Frequency Switch Based on Photonics.

    Science.gov (United States)

    Ge, Jia; Fok, Mable P

    2015-11-26

    Microwave switches, or Radio Frequency (RF) switches have been intensively used in microwave systems for signal routing. Compared with the fast development of microwave and wireless systems, RF switches have been underdeveloped particularly in terms of switching speed and operating bandwidth. In this paper, we propose a photonics based RF switch that is capable of switching at tens of picoseconds speed, which is hundreds of times faster than any existing RF switch technologies. The high-speed switching property is achieved with the use of a rapidly tunable microwave photonic filter with tens of gigahertz frequency tuning speed, where the tuning mechanism is based on the ultra-fast electro-optics Pockels effect. The RF switch has a wide operation bandwidth of 12 GHz and can go up to 40 GHz, depending on the bandwidth of the modulator used in the scheme. The proposed RF switch can either work as an ON/OFF switch or a two-channel switch, tens of picoseconds switching speed is experimentally observed for both type of switches.

  17. Vibration characteristics of dental high-speed turbines and speed-increasing handpieces.

    Science.gov (United States)

    Poole, Ruth L; Lea, Simon C; Dyson, John E; Shortall, Adrian C C; Walmsley, A Damien

    2008-07-01

    Vibrations of dental handpieces may contribute to symptoms of hand-arm vibration syndrome in dental personnel and iatrogenic enamel cracking in teeth. However, methods for measuring dental handpiece vibrations have previously been limited and information about vibration characteristics is sparse. This preliminary study aimed to use a novel approach to assess the vibrations of unloaded high-speed handpieces in vitro. Maximum vibration displacement amplitudes of five air turbines and two speed-increasing handpieces were recorded whilst they were operated with and without a rotary cutting instrument (RCI) using a scanning laser vibrometer (SLV). RCI rotation speeds, calculated from frequency peaks, were consistent with expected values. ANOVA statistical analysis indicated significant differences in vibrations between handpiece models (p0.11). Operating handpieces with a RCI resulted in greater vibrations than with no RCI (pmeasurement exceeded 4 microm for the handpieces in the current test setup (implying that these vibrations may be unlikely to cause adverse effects), this study has formed the basis for future work which will include handpiece vibration measurements whilst cutting under clinically representative loads.

  18. Superconducting magnet suspensions in high speed ground transport

    Energy Technology Data Exchange (ETDEWEB)

    Alston, I A

    1973-08-01

    A technical and economic definition of high speed ground transport systems using magnetic suspensions is given. The full range of common superconducting suspensions and of propulsions are covered with designs produced for speeds ranging from 100 m/s (225 miles/hr) to 250 m/s (560 mile/hr). Technical descriptions of the vehicles, their suspensions, propulsions and tracks are given in some detail and operating costs are presented for all the systems together with details of the breakdown of costs and the capital costs involved. The design assumptions, the costing procedure and a cost sensitivity study are presented. It is concluded that the systems are technically feasible; that they are suited to existing duorail track for low speed running and that, in these circumstances, they would be economically viable over many routes.

  19. Experimental investigation on a high subsonic compressor cascade flow

    Directory of Open Access Journals (Sweden)

    Zhang Haideng

    2015-08-01

    Full Text Available With the aim of deepening the understanding of high-speed compressor cascade flow, this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow. With the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient increases. Cross flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex structures. Passage vortex is the main corner separation vortex. During its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting circle. With higher incidence, corner separation is further deteriorated, leading to higher flow loss. Meanwhile, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of incidence. Compared with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the cascade. Results obtained present details of high-speed compressor cascade flow, which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.

  20. Schlieren study of a sonic jet injected into a supersonic cross flow using high-current pulsed LEDs

    NARCIS (Netherlands)

    Giskes, Ella; Verschoof, Ruben A.; Segerink, Frans B.; Venner, Cornelis H.

    2017-01-01

    Benefiting from the development of increasingly advanced high speed cameras, flow visualization and analysis nowadays yield detailed data of the flow field in many applications. Notwithstanding this progress, for high speed and supersonic flows it is still not trivial to capture high quality images.

  1. High speed intravascular photoacoustic imaging of atherosclerotic arteries (Conference Presentation)

    Science.gov (United States)

    Piao, Zhonglie; Ma, Teng; Qu, Yueqiao; Li, Jiawen; Yu, Mingyue; He, Youmin; Shung, K. Kirk; Zhou, Qifa; Kim, Chang-Seok; Chen, Zhongping

    2016-02-01

    Cardiovascular disease is the leading cause of death in the industrialized nations. Accurate quantification of both the morphology and composition of lipid-rich vulnerable atherosclerotic plaque are essential for early detection and optimal treatment in clinics. In previous works, intravascular photoacoustic (IVPA) imaging for detection of lipid-rich plaque within coronary artery walls has been demonstrated in ex vivo, but the imaging speed is still limited. In order to increase the imaging speed, a high repetition rate laser is needed. In this work, we present a high speed integrated IVPA/US imaging system with a 500 Hz optical parametric oscillator laser at 1725 nm. A miniature catheter with 1.0 mm outer diameter was designed with a 200 μm multimode fiber and an ultrasound transducer with 45 MHz center frequency. The fiber was polished at 38 degree and enclosed in a glass capillary for total internal reflection. An optical/electrical rotary junction and pull-back mechanism was applied for rotating and linearly scanning the catheter to obtain three-dimensional imaging. Atherosclerotic rabbit abdominal aorta was imaged as two frame/second at 1725 nm. Furthermore, by wide tuning range of the laser wavelength from 1680 nm to 1770 nm, spectroscopic photoacoustic analysis of lipid-mimicking phantom and an human atherosclerotic artery was performed ex vivo. The results demonstrated that the developed IVPA/US imaging system is capable for high speed intravascular imaging for plaque detection.

  2. High speed corner and gap-seal computations using an LU-SGS scheme

    Science.gov (United States)

    Coirier, William J.

    1989-01-01

    The hybrid Lower-Upper Symmetric Gauss-Seidel (LU-SGS) algorithm was added to a widely used series of 2D/3D Euler/Navier-Stokes solvers and was demonstrated for a particular class of high-speed flows. A limited study was conducted to compare the hybrid LU-SGS for approximate Newton iteration and diagonalized Beam-Warming (DBW) schemes on a work and convergence history basis. The hybrid LU-SGS algorithm is more efficient and easier to implement than the DBW scheme originally present in the code for the cases considered. The code was validated for the hypersonic flow through two mutually perpendicular flat plates and then used to investigate the flow field in and around a simplified scramjet module gap seal configuration. Due to the similarities, the gap seal flow was compared to hypersonic corner flow at the same freestream conditions and Reynolds number.

  3. Mixed Platoon Flow Dispersion Model Based on Speed-Truncated Gaussian Mixture Distribution

    Directory of Open Access Journals (Sweden)

    Weitiao Wu

    2013-01-01

    Full Text Available A mixed traffic flow feature is presented on urban arterials in China due to a large amount of buses. Based on field data, a macroscopic mixed platoon flow dispersion model (MPFDM was proposed to simulate the platoon dispersion process along the road section between two adjacent intersections from the flow view. More close to field observation, truncated Gaussian mixture distribution was adopted as the speed density distribution for mixed platoon. Expectation maximum (EM algorithm was used for parameters estimation. The relationship between the arriving flow distribution at downstream intersection and the departing flow distribution at upstream intersection was investigated using the proposed model. Comparison analysis using virtual flow data was performed between the Robertson model and the MPFDM. The results confirmed the validity of the proposed model.

  4. Effect of Sweep on Cavity Flow Fields at Subsonic and Transonic Speeds

    Science.gov (United States)

    Tracy, Maureen B.; Plentovich, Elizabeth B.; Hemsch, Michael J.; Wilcox, Floyd J.

    2012-01-01

    An experimental investigation was conducted in the NASA Langley 7 x 10-Foot High Speed Tunnel (HST) to study the effect of leading- and trailing-edge sweep on cavity flow fields for a range of cavity length-to-height (l/h) ratios. The free-stream Mach number was varied from 0.2 to 0.8. The cavity had a depth of 0.5 inches, a width of 2.5 inches, and a maximum length of 12.0 inches. The leading- and trailing-edge sweep was adjusted using block inserts to achieve leading edge sweep angles of 65 deg, 55 deg, 45 deg, 35 deg, and 0 deg. The fore and aft cavity walls were always parallel. The aft wall of the cavity was remotely positioned to achieve a range of length-to-depth ratios. Fluctuating- and static-pressure data were obtained on the floor of the cavity. The fluctuating pressure data were used to determine whether or not resonance occurred in the cavity rather than to provide a characterization of the fluctuating pressure field. Qualitative surface flow visualization was obtained using a technique in which colored water was introduced into the model through static-pressure orifices. A complete tabulation of the mean static-pressure data for the swept leading edge cavities is included.

  5. Development of Industrial High-Speed Transfer Parallel Robot

    International Nuclear Information System (INIS)

    Kim, Byung In; Kyung, Jin Ho; Do, Hyun Min; Jo, Sang Hyun

    2013-01-01

    Parallel robots used in industry require high stiffness or high speed because of their structural characteristics. Nowadays, the importance of rapid transportation has increased in the distribution industry. In this light, an industrial parallel robot has been developed for high-speed transfer. The developed parallel robot can handle a maximum payload of 3 kg. For a payload of 0.1 kg, the trajectory cycle time is 0.3 s (come and go), and the maximum velocity is 4.5 m/s (pick amp, place work, adept cycle). In this motion, its maximum acceleration is very high and reaches approximately 13g. In this paper, the design, analysis, and performance test results of the developed parallel robot system are introduced

  6. An Investigation of Surge in a High-Speed Centrifugal Compressor Using Digital PIV

    Science.gov (United States)

    Wernet, Mark P.; Bright, Michelle M.; Skoch, Gary J.

    2002-01-01

    Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a loss of engine power, large pressure transients in the inlet/nacelle and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to successfully control these events. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to simultaneously capture transient velocity and pressure measurements in the non-stationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique which is ideally suited for studying transient flow phenomena in high speed turbomachinery and has been used previously to successfully map the stable operating point flow field in the diffuser of a high speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

  7. Multivariable Techniques for High-Speed Research Flight Control Systems

    Science.gov (United States)

    Newman, Brett A.

    1999-01-01

    This report describes the activities and findings conducted under contract with NASA Langley Research Center. Subject matter is the investigation of suitable multivariable flight control design methodologies and solutions for large, flexible high-speed vehicles. Specifically, methodologies are to address the inner control loops used for stabilization and augmentation of a highly coupled airframe system possibly involving rigid-body motion, structural vibrations, unsteady aerodynamics, and actuator dynamics. Design and analysis techniques considered in this body of work are both conventional-based and contemporary-based, and the vehicle of interest is the High-Speed Civil Transport (HSCT). Major findings include: (1) control architectures based on aft tail only are not well suited for highly flexible, high-speed vehicles, (2) theoretical underpinnings of the Wykes structural mode control logic is based on several assumptions concerning vehicle dynamic characteristics, and if not satisfied, the control logic can break down leading to mode destabilization, (3) two-loop control architectures that utilize small forward vanes with the aft tail provide highly attractive and feasible solutions to the longitudinal axis control challenges, and (4) closed-loop simulation sizing analyses indicate the baseline vane model utilized in this report is most likely oversized for normal loading conditions.

  8. High-speed technique based on a parallel projection correlation procedure for digital image correlation

    Science.gov (United States)

    Zaripov, D. I.; Renfu, Li

    2018-05-01

    The implementation of high-efficiency digital image correlation methods based on a zero-normalized cross-correlation (ZNCC) procedure for high-speed, time-resolved measurements using a high-resolution digital camera is associated with big data processing and is often time consuming. In order to speed-up ZNCC computation, a high-speed technique based on a parallel projection correlation procedure is proposed. The proposed technique involves the use of interrogation window projections instead of its two-dimensional field of luminous intensity. This simplification allows acceleration of ZNCC computation up to 28.8 times compared to ZNCC calculated directly, depending on the size of interrogation window and region of interest. The results of three synthetic test cases, such as a one-dimensional uniform flow, a linear shear flow and a turbulent boundary-layer flow, are discussed in terms of accuracy. In the latter case, the proposed technique is implemented together with an iterative window-deformation technique. On the basis of the results of the present work, the proposed technique is recommended to be used for initial velocity field calculation, with further correction using more accurate techniques.

  9. Coronal holes and high-speed wind streams

    International Nuclear Information System (INIS)

    Zirker, J.B.

    1977-01-01

    Coronal holes low have been identified as Bartel's M regions, i.e., sources of high-speed wind streams that produce recurrent geomagnetic variations. Throughout the Skylab period the polar caps of the Sun were coronal holes, and at lower latitudes the most persistent and recurrent holes were equatorial extensions of the polar caps. The holes rotated 'rigidly' at the equatorial synodic rate. They formed in regions of unipolar photospheric magnetic field, and their internal magnetic fields diverged rapidly with increasing distance from the sun. The geometry of the magnetic field in the inner corona seems to control both the physical properties of the holes and the global distribution of high-speed wind streams in the heliosphere. The latitude variation of the divergence of the coronal magnetic field lines produces corresponding variations in wind speed.During the years of declining solar activity the global field of the corona approximates a perturbed dipole. The divergence of field lines in each hemisphere produces a high-speed wind near the poles and low-speed wind in a narrow belt that coincides with the magnetic neutral sheet. The analysis of electron density measurements within a polar hole indicates that solar wind is accelerated principally in the region between 2 and 5 R/sub s/ and that mechanical wave pressure (possibly Alfven wave) may be responsible for the accleration of the wind. Phenomenological models for the birth and decay of coronal holes have been proposed. Attempts to explain the birth and rigid rotation of holes through dynamo action have been only partially successful. The 11-year variation of cosmic ray intensities at the earth may result from cyclic variation of open field regions associated with coronal holes

  10. Unified approach to the study of solid fuel combustion characteristics at high airflow speeds

    Science.gov (United States)

    Vnuchkov, D. A.; Lukashevich, S. V.; Nalivaychenko, D. G.; Zvegintsev, V. I.

    2017-10-01

    The main objective of the research is the development of guidelines for a unified approach to testing the combustion of different solid fuels in gaseous oxidant high-speed flow, so that research outcomes could be presented in a standardized and cohesive form. All the experiments were performed on a special experimental installation designed for quantification of the burning characteristics of different fuels in a wide range of the airflow parameters at the same geometry of the combustion chamber.

  11. Active Control of High-Speed Free Jets Using High-Frequency Excitation

    Science.gov (United States)

    Upadhyay, Puja

    Control of aerodynamic noise generated by high-performance jet engines continues to remain a serious problem for the aviation community. Intense low frequency noise produced by large-scale coherent structures is known to dominate acoustic radiation in the aft angles. A tremendous amount of research effort has been dedicated towards the investigation of many passive and active flow control strategies to attenuate jet noise, while keeping performance penalties to a minimum. Unsteady excitation, an active control technique, seeks to modify acoustic sources in the jet by leveraging the naturally-occurring flow instabilities in the shear layer. While excitation at a lower range of frequencies that scale with the dynamics of large-scale structures, has been attempted by a number of studies, effects at higher excitation frequencies remain severely unexplored. One of the major limitations stems from the lack of appropriate flow control devices that have sufficient dynamic response and/or control authority to be useful in turbulent flows, especially at higher speeds. To this end, the current study seeks to fulfill two main objectives. First, the design and characterization of two high-frequency fluidic actuators (25 and 60 kHz) are undertaken, where the target frequencies are guided by the dynamics of high-speed free jets. Second, the influence of high-frequency forcing on the aeroacoustics of high-speed jets is explored in some detail by implementing the nominally 25 kHz actuator on a Mach 0.9 (Re D = 5 x 105) free jet flow field. Subsequently, these findings are directly compared to the results of steady microjet injection experiments performed in the same rig and to prior jet noise control studies, where available. Finally, limited acoustic measurements were also performed by implementing the nominally 25 kHz actuators on jets at higher Mach numbers, including shock containing jets, and elevated temperatures. Using lumped element modeling as an initial guide, the current

  12. Investigation on Flow-Induced Noise due to Backflow in Low Specific Speed Centrifugal Pumps

    Directory of Open Access Journals (Sweden)

    Qiaorui Si

    2013-01-01

    Full Text Available Flow-induced noise causes disturbances during the operation of centrifugal pumps and also affects their performance. The pumps often work at off-design conditions, mainly at part-load conditions, because of frequent changes in the pump device system. Consequently numerous unstable phenomena occur. In low specific speed centrifugal pumps the main disturbance is the inlet backflow, which is considered as one of the most important factors of flow-induced noise and vibration. In this study, a test rig of the flow-induced noise and vibration of the centrifugal pump was built to collect signals under various operating conditions. The three-dimensional unsteady flow of centrifugal pumps was calculated based on the Reynolds-averaged equations that resemble the shear stress transport (SST k-ω turbulence model. The results show that the blade passing frequency and shaft frequency are dominant in the spectrum of flow-induced noise, whereas the shaft component, amplitude value at shaft frequency, and peak frequencies around the shaft increase with decreasing flow. Through flow field analysis, the inlet backflow of the impeller occurs under 0.7 times the design flow. The pressure pulsation spectrum with backflow conditions validates the flow-induced noise findings. The velocity characteristics of the backflow zone at the inlet pipe were analyzed, and the dynamic characteristics of the backflow eddy during one impeller rotating period were simultaneously obtained by employing the backflow conditions. A flow visualization experiment was performed to confirm the numerical calculations.

  13. On-Chip Enucleation of Bovine Oocytes using Microrobot-Assisted Flow-Speed Control

    Directory of Open Access Journals (Sweden)

    Akihiko Ichikawa

    2013-06-01

    Full Text Available In this study, we developed a microfluidic chip with a magnetically driven microrobot for oocyte enucleation. A microfluidic system was specially designed for enucleation, and the microrobot actively controls the local flow-speed distribution in the microfluidic chip. The microrobot can adjust fluid resistances in a channel and can open or close the channel to control the flow distribution. Analytical modeling was conducted to control the fluid speed distribution using the microrobot, and the model was experimentally validated. The novelties of the developed microfluidic system are as follows: (1 the cutting speed improved significantly owing to the local fluid flow control; (2 the cutting volume of the oocyte can be adjusted so that the oocyte undergoes less damage; and (3 the nucleus can be removed properly using the combination of a microrobot and hydrodynamic forces. Using this device, we achieved a minimally invasive enucleation process. The average enucleation time was 2.5 s and the average removal volume ratio was 20%. The proposed new system has the advantages of better operation speed, greater cutting precision, and potential for repeatable enucleation.

  14. Flow and free running speed characterization of dental air turbine handpieces.

    Science.gov (United States)

    Dyson, J E; Darvell, B W

    1999-09-01

    Dental air turbine handpieces have been widely used in clinical dentistry for over 30 years, yet little work has been reported on their performance. A few studies have been concerned with measurement of speed (i.e. rotation rate), torque and power performance of these devices, but neither investigations of functional relationships between controlling variables nor theory dealing specifically with this class of turbine have been reported. This has hindered the development of satisfactory methods of handpiece specification and of testing dental rotary cutting tools. It was the intention of the present work to remedy that deficiency. Measurements of pressure, temperature, gas flow rate and rotation rate were made with improved accuracy and precision for 14 ball bearing turbine handpieces on several gases. Functional relationships between gas properties, supply pressure, flow rate, turbine design factors and free running speed were identified and equations describing these aspects of behaviour of this class of turbine developed. The rotor radius, through peripheral Mach number, was found to be a major determinant of speed performance. In addition, gas flow was found to be an important limiting factor through the effect of choke. Each dental handpiece can be treated as a simple orifice of a characteristic cross-sectional area. Free running speed can be explained in terms of gas properties and pressure, with allowance for a design-specific performance coefficient.

  15. Highball: A high speed, reserved-access, wide area network

    Science.gov (United States)

    Mills, David L.; Boncelet, Charles G.; Elias, John G.; Schragger, Paul A.; Jackson, Alden W.

    1990-01-01

    A network architecture called Highball and a preliminary design for a prototype, wide-area data network designed to operate at speeds of 1 Gbps and beyond are described. It is intended for applications requiring high speed burst transmissions where some latency between requesting a transmission and granting the request can be anticipated and tolerated. Examples include real-time video and disk-disk transfers, national filestore access, remote sensing, and similar applications. The network nodes include an intelligent crossbar switch, but have no buffering capabilities; thus, data must be queued at the end nodes. There are no restrictions on the network topology, link speeds, or end-end protocols. The end system, nodes, and links can operate at any speed up to the limits imposed by the physical facilities. An overview of an initial design approach is presented and is intended as a benchmark upon which a detailed design can be developed. It describes the network architecture and proposed access protocols, as well as functional descriptions of the hardware and software components that could be used in a prototype implementation. It concludes with a discussion of additional issues to be resolved in continuing stages of this project.

  16. High-speed imaging polarimetry using liquid crystal modulators

    Directory of Open Access Journals (Sweden)

    Ambs P.

    2010-06-01

    Full Text Available This paper deals with dynamic polarimetric imaging techniques. The basics of modern polarimetry have been known for one and a half century, but no practical high-speed implementation providing the full polarization information is currently available. Various methods are reviewed which prove to be a trade-off between the complexity of the optical set-up and the amount of polarimetric information they provide (ie the number of components of the Stokes vector. Techniques using liquid crystal devices, incepted in the late 1990's, are emphasized. Optical set-ups we implemented are presented. We particularly focus on high-speed techniques (i.e. faster than 200 Hz using ferroelectric liquid crystal devices.

  17. Nanocrystalline Ni-Co Alloy Synthesis by High Speed Electrodeposition

    Directory of Open Access Journals (Sweden)

    Jamaliah Idris

    2013-01-01

    Full Text Available Electrodeposition of nanocrystals is economically and technologically viable production path for the synthesis of pure metals and alloys both in coatings and bulk form. The study presents nanocrystalline Ni-Co alloy synthesis by high speed electrodeposition. Nanocrystalline Ni-Co alloys coatings were prepared by direct current (DC and deposited directly on steel and aluminum substrates without any pretreatment, using high speed electrodeposition method. The influence of the electrolysis parameters, such as cathodic current density and temperature at constant pH, on electrodeposition and microstructure of Ni-Co alloys were examined. A homogeneous surface morphology was obtained at all current densities of the plated samples, and it was evident that the current density and temperature affect the coating thickness of Ni-Co alloy coatings.

  18. The high speed interconnect system architecture and operation

    Science.gov (United States)

    Anderson, Steven C.

    The design and operation of a fiber-optic high-speed interconnect system (HSIS) being developed to meet the requirements of future avionics and flight-control hardware with distributed-system architectures are discussed. The HSIS is intended for 100-Mb/s operation of a local-area network with up to 256 stations. It comprises a bus transmission system (passive star couplers and linear media linked by active elements) and network interface units (NIUs). Each NIU is designed to perform the physical, data link, network, and transport functions defined by the ISO OSI Basic Reference Model (1982 and 1983) and incorporates a fiber-optic transceiver, a high-speed protocol based on the SAE AE-9B linear token-passing data bus (1986), and a specialized application interface unit. The operating modes and capabilities of HSIS are described in detail and illustrated with diagrams.

  19. High-speed digital holographic interferometry for vibration measurement

    International Nuclear Information System (INIS)

    Pedrini, Giancarlo; Osten, Wolfgang; Gusev, Mikhail E.

    2006-01-01

    A system based on digital holographic interferometry for the measurement of vibrations is presented. A high-power continuous laser(10 W) and a high-speed CCD camera are used. Hundreds of holograms of an object that has been subjected to dynamic deformation are recorded. The acquisition speed and the time of exposure of the detector are determined by the vibration frequency. Two methods are presented for triggering the camera in order to acquire at a given phase of the vibration. The phase of the wavefront is calculated from the recorded holograms by use of a two-dimensional digital Fourier-transform method. The deformation of the object is obtained from the phase. By combination of the deformations recorded at different times it is possible to reconstruct the vibration of the object

  20. Multimode polymer waveguides for high-speed optical interconnects

    Science.gov (United States)

    Bamiedakis, N.; Ingham, J. D.; Penty, R. V.; White, I. H.; DeGroot, J. V.; Clapp, T. V.

    2017-11-01

    Polymeric multimode waveguides are of particular interest for optical interconnections in short-reach data links. In some applications, for example in space-borne systems, the use of advanced materials with outstanding performance in extreme environments is required (temperature and radiation). In this paper therefore, we present novel siloxane polymers suitable for these applications. The materials are used to form straight, 90° bent and spiral polymer waveguides by low-cost conventional photolithographic techniques on FR4 substrates. The samples have been tested to investigate their propagation characteristics and demonstrate their potential for high-speed data links. Overall, there is strong evidence that these multimode waveguides can be successfully employed as high-speed short-reach data links. Their excellent thermal properties, their low cost and the simple fabrication process indicate their suitability for a wide range of space applications.

  1. High-speed nonvolatile CMOS/MNOS RAM

    International Nuclear Information System (INIS)

    Derbenwick, G.F.; Dodson, W.D.; Sokel, R.J.

    1979-01-01

    A bulk silicon technology for a high-speed static CMOS/MNOS RAM has been developed. Radiation-hardened, high voltage CMOS circuits have been fabricated for the memory array driving circuits and the enhancement-mode p-channel MNOS memory transistors have been fabricated using a native tunneling oxide with a 45 nm CVD Si 3 N 4 insulator deposited at 750 0 C. Read cycle times less than 350 ns and write cycle times of 1 μs are projected for the final 1Kx1 design. The CMOS circuits provide adequate speed for the write and read cycles and minimize the standby power dissipation. Retention times well in excess of 30 min are projected

  2. High-speed Integrated Circuits for electrical/Optical Interfaces

    DEFF Research Database (Denmark)

    Jespersen, Christoffer Felix

    2008-01-01

    This thesis is a continuation of the effort to increase the bandwidth of communicationnetworks. The thesis presents the results of the design of several high-speed electrical ircuits for an electrical/optical interface. These circuits have been a contribution to the ESTA project in collaboration...... circuits at the receiver interface, though VCOs are also found in the transmitter where a multitude of independent sources have to be mutually synchronized before multiplexing. The circuits are based on an InP DHBT process (VIP-2) supplied by Vitesse and made publicly available as MPW. The VIP-2 process...... represents the avant-garde of InP technology, with ft and fmax well above 300 GHz. Principles of high speed design are presented and described as a useful background before proceeding to circuits. A static divider is used as an example to illustrate many of the design principles. Theory and fundamentals...

  3. High-speed packet filtering utilizing stream processors

    Science.gov (United States)

    Hummel, Richard J.; Fulp, Errin W.

    2009-04-01

    Parallel firewalls offer a scalable architecture for the next generation of high-speed networks. While these parallel systems can be implemented using multiple firewalls, the latest generation of stream processors can provide similar benefits with a significantly reduced latency due to locality. This paper describes how the Cell Broadband Engine (CBE), a popular stream processor, can be used as a high-speed packet filter. Results show the CBE can potentially process packets arriving at a rate of 1 Gbps with a latency less than 82 μ-seconds. Performance depends on how well the packet filtering process is translated to the unique stream processor architecture. For example the method used for transmitting data and control messages among the pseudo-independent processor cores has a significant impact on performance. Experimental results will also show the current limitations of a CBE operating system when used to process packets. Possible solutions to these issues will be discussed.

  4. High speed movies of turbulence in Alcator C-Mod

    International Nuclear Information System (INIS)

    Terry, J.L.; Zweben, S.J.; Bose, B.; Grulke, O.; Marmar, E.S.; Lowrance, J.; Mastrocola, V.; Renda, G.

    2004-01-01

    A high speed (250 kHz), 300 frame charge coupled device camera has been used to image turbulence in the Alcator C-Mod Tokamak. The camera system is described and some of its important characteristics are measured, including time response and uniformity over the field-of-view. The diagnostic has been used in two applications. One uses gas-puff imaging to illuminate the turbulence in the edge/scrape-off-layer region, where D 2 gas puffs localize the emission in a plane perpendicular to the magnetic field when viewed by the camera system. The dynamics of the underlying turbulence around and outside the separatrix are detected in this manner. In a second diagnostic application, the light from an injected, ablating, high speed Li pellet is observed radially from the outer midplane, and fast poloidal motion of toroidal striations are seen in the Li + light well inside the separatrix

  5. Corrosion Inhibition of High Speed Steel by Biopolymer HPMC Derivatives

    Directory of Open Access Journals (Sweden)

    Shih-Chen Shi

    2016-07-01

    Full Text Available The corrosion inhibition characteristics of the derivatives of biopolymer hydroxypropyl methylcellulose (HPMC, hydroxypropyl methylcellulose phthalate (HPMCP, and hydroxypropyl methylcellulose acetate succinate (HPMCAS film are investigated. Based on electrochemical impedance spectroscopic measurements and potentiodynamic polarization, the corrosion inhibition performance of high speed steel coated with HPMC derivatives is evaluated. The Nyquist plot and Tafel polarization demonstrate promising anti-corrosion performance of HPMC and HPMCP. With increasing film thickness, both materials reveal improvement in corrosion inhibition. Moreover, because of a hydrophobic surface and lower moisture content, HPMCP shows better anti-corrosion performance than HPMCAS. The study is of certain importance for designing green corrosion inhibitors of high speed steel surfaces by the use of biopolymer derivatives.

  6. High speed turning of compacted graphite iron using controlled modulation

    Science.gov (United States)

    Stalbaum, Tyler Paul

    Compacted graphite iron (CGI) is a material which emerged as a candidate material to replace cast iron (CI) in the automotive industry for engine block castings. Its thermal and mechanical properties allow the CGI-based engines to operate at higher cylinder pressures and temperatures than CI-based engines, allowing for lower fuel emissions and increased fuel economy. However, these same properties together with the thermomechanical wear mode in the CGI-CBN system result in poor machinability and inhibit CGI from seeing wide spread use in the automotive industry. In industry, machining of CGI is done only at low speeds, less than V = 200 m/min, to avoid encountering rapid wear of the cutting tools during cutting. Studies have suggested intermittent cutting operations such as milling suffer less severe tool wear than continuous cutting. Furthermore, evidence that a hard sulfide layer which forms over the cutting edge in machining CI at high speeds is absent during machining CGI is a major factor in the difference in machinability of these material systems. The present study addresses both of these issues by modification to the conventional machining process to allow intermittent continuous cutting. The application of controlled modulation superimposed onto the cutting process -- modulation-assisted machining (MAM) -- is shown to be quite effective in reducing the wear of cubic boron nitride (CBN) tools when machining CGI at high machining speeds (> 500 m/min). The tool life is at least 20 times greater than found in conventional machining of CGI. This significant reduction in wear is a consequence of reduction in the severity of the tool-work contact conditions with MAM. The propensity for thermochemical wear of CBN is thus reduced. It is found that higher cutting speed (> 700 m/min) leads to lower tool wear with MAM. The MAM configuration employing feed-direction modulation appears feasible for implementation at high speeds and offers a solution to this challenging

  7. Assessment of Human Ambulatory Speed by Measuring Near-Body Air Flow

    Directory of Open Access Journals (Sweden)

    Stefano Salati

    2010-09-01

    Full Text Available Accurate measurements of physical activity are important for the diagnosis of the exacerbation of chronic diseases. Accelerometers have been widely employed in clinical research for measuring activity intensity and investigating the association between physical activity and adverse health conditions. However, the ability of accelerometers in assessing physical activity intensity such as walking speed has been constrained by the inter-individual variability in sensor output and by the necessity of developing unobtrusive low-power monitoring systems. This paper will present a study aimed at investigating the accuracy of a wearable measuring system of near-body air flow to determine ambulatory speed in the field.

  8. Wetting dynamics at high values of contact line speed

    OpenAIRE

    Пономарев, К. О.; Феоктистов, Дмитрий Владимирович; Орлова, Евгения Георгиевна

    2015-01-01

    Experimental results analyses of dynamic contact angle change under the conditions of substrate wetting by distilled water at high values of the contact line speed was conducted. Three spreading modes for copper substrates with different roughness were selected: drop formation, spreading and equilibrium contact angle formation. Peculiarity of droplet spreading on superhydrophobic surface is found. It consists in a monotonic increase of the advancing dynamic contact angle. The effect of the dr...

  9. High Speed White Dwarf Asteroseismology with the Herty Hall Cluster

    Science.gov (United States)

    Gray, Aaron; Kim, A.

    2012-01-01

    Asteroseismology is the process of using observed oscillations of stars to infer their interior structure. In high speed asteroseismology, we complete that by quickly computing hundreds of thousands of models to match the observed period spectra. Each model on a single processor takes five to ten seconds to run. Therefore, we use a cluster of sixteen Dell Workstations with dual-core processors. The computers use the Ubuntu operating system and Apache Hadoop software to manage workloads.

  10. Aero-Mechanical Coupling in a High-Speed Compressor

    Science.gov (United States)

    2010-02-01

    freedom mass-spring- damper system as χ = ς 2 √ κµ . (51) ς represents the viscous damping, κ is the system stiffness and µ the system mass. χ expresses...between the fluid and structures which are common in modern, high-speed axial compressors. There were two major areas of focus. The first was the...development of measurement technique specifically for the study of these phenomena, termed Blade Image Velocimetry (BIV). The technique can measure fluid and

  11. Modeling and simulation of high-speed milling centers dynamics

    OpenAIRE

    Msaddek , El Bechir; Bouaziz , Zoubeir; Baili , Maher; Dessein , Gilles

    2011-01-01

    International audience; High-speed machining is a milling operation in industrial production of aeronautic parts, molds, and dies. The parts production is being reduced because of the slowing down of the machining resulting from the tool path discontinuity machining strategy. In this article, we propose a simulation tool of the machine dynamic behavior, in complex parts machining. For doing this, analytic models have been developed expressing the cutting tool feed rate. Afterwards, a simulati...

  12. The economic effects of high speed rail investment

    OpenAIRE

    de Rus, Ginés

    2008-01-01

    The allocation of traffic between different transport modes follows transport user decisions which depend on the generalized cost of travel in the available alternatives. High Speed Rail (HSR) investment is a government decision with significant effects on the generalized cost of rail transport; and therefore on the modal split in corridors where private operators compete for traffic and charge prices close to total producer costs (infrastructure included). The rationale for HSR investment is...

  13. Kinematic and Kinetic Evaluation of High Speed Backward Running

    Science.gov (United States)

    1999-06-30

    Designed using Perform Pro , WHS/DIOR, Oct 94 KINEMATIC AND KINETIC EVALUATION OF HIGH SPEED BACKWARD RUNNING by ALAN WAYNE ARATA A DISSERTATION...Project Manager, Engineering Division, Kelly Air Force Base, Texas, 1983-86 AWARDS AND HONORS: All-American, 50yd Freestyle , 1979 Winner, Rocky...redirection #include <stdlib.h> // for exit #include <iomanip.h> // for set precision #include <string.h> // for string copy const int NUMPOINTS

  14. Study on Electromagnetic Interference of high-speed railway EMU

    OpenAIRE

    CHENG Qiang; LIU Jin-jiang; CHENG Ning

    2013-01-01

    Electromagnetic radiation generated by pantograph-catenaries detachment is one of the inevitable problems with the development of high-speed railway this paper is focusing on the generating mechanism and characteristics of electromagnetic noise caused by pantograph-catenaries system. Based on previous research, we build an integrated model of catenaries and locomotive system, and study the electromagnetic disturbance characteristics using software FEKO. The simulation experiment results in th...

  15. High speed trains Velaro for Russia; Hochgeschwindigkeitszuege Velaro fuer Russland

    Energy Technology Data Exchange (ETDEWEB)

    Lipp, Andreas; John, David [Siemens AG, I MO TR HI RUS, Erlangen (Germany); Mangler, Ruediger [Siemens AG, I MO TR DH, Krefeld (Germany); Nazarov, Aleksander S. [OAO RZD, Moscow (Russian Federation). Dept. of Technical Policy; Nazarov, Oleg N. [VNIIZhT Moscow (Russian Federation); Shilkin, Vitali P. [OAO RZD, Moscow (Russian Federation)

    2008-07-01

    From December 2008 on, eight ten-piece high-speed trains from the Velaro family from Siemens will be delivered to Russia. The two electrical multiple unit versions - single and double system trains equipped with distributed traction - will be put into service on the existing Moscow - St. Petersburg and Moscow - Nizhni Novgorod lines. The technical design and the special features for deployment in Russia are described. (orig.)

  16. Gearbox Reliability Collaborative High-Speed Shaft Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Keller, J.; McNiff, B.

    2014-09-01

    Instrumentation has been added to the high-speed shaft, pinion, and tapered roller bearing pair of the Gearbox Reliability Collaborative gearbox to measure loads and temperatures. The new shaft bending moment and torque instrumentation was calibrated and the purpose of this document is to describe this calibration process and results, such that the raw shaft bending and torque signals can be converted to the proper engineering units and coordinate system reference for comparison to design loads and simulation model predictions.

  17. Open tube guideway for high speed air cushioned vehicles

    Science.gov (United States)

    Goering, R. S. (Inventor)

    1974-01-01

    This invention is a tubular shaped guideway for high-speed air-cushioned supported vehicles. The tubular guideway is split and separated such that the sides of the guideway are open. The upper portion of the tubular guideway is supported above the lower portion by truss-like structural members. The lower portion of the tubular guideway may be supported by the terrain over which the vehicle travels, on pedestals or some similar structure.

  18. Noise factor of a high-speed cinematography system

    International Nuclear Information System (INIS)

    Secroun, A.

    2000-01-01

    Inertial confinement fusion simulates in a laboratory the thermodynamic state of the center of stars, thus leading to the determination of stellar parameters. In order to reach that aim, high-speed cinematography brings up instruments specifically adapted to picosecond measurement, for which it is necessary to know the final precision. A model of the noise factor of the instruments under study is introduced and confronted to the experimental results obtained. (authors)

  19. Plant analyzer development for high-speed interactive simulation of BWR plant transients

    International Nuclear Information System (INIS)

    Wulff, W.; Cheng, H.S.; Mallen, A.N.

    1986-01-01

    Advanced modeling techniques have been combined with modern, special-purpose peripheral minicomputer technology to develop a plant analyzer which provides realistic and accurate predictions of plant transients and severe off-normal events in nuclear power plants through on-line simulations at speeds of approximately 10 times faster than actual process speeds. The new simulation technology serves not only for carrying out routinely and efficiently safety analyses, optimizations of emergency procedures and design changes, parametric studies for obtaining safety margins and for generic training but also for assisting plant operations. Five modeling principles are presented which serve to achieve high-speed simulation of neutron kinetics, thermal conduction, nonhomogeneous and nonequilibrium two-phase flow coolant dynamics, steam line acoustical effects, and the dynamics of the balance of plant and containment systems, control systems and plant protection systems. 21 refs

  20. Development and characterization of high-frequency resonance-enhanced microjet actuators for control of high-speed jets

    Science.gov (United States)

    Upadhyay, Puja; Gustavsson, Jonas P. R.; Alvi, Farrukh S.

    2016-05-01

    For flow control applications requiring high-frequency excitation, very few actuators have sufficient dynamic response and/or control authority to be useful in high-speed flows. Due to this reason, experiments involving high-frequency excitation, attempted in the past, have been limited to either low-frequency actuation with reasonable control authority or moderate-frequency actuation with limited control authority. The current work expands on the previous development of the resonance-enhanced microactuators to design actuators that are capable of producing high-amplitude pulses at much higher frequencies [{O} (10 kHz)]. Using lumped element modeling, two actuators have been designed with nominal frequencies of 20 and 50 kHz. Extensive benchtop characterization using acoustic measurements as well as optical diagnostics using a high-resolution micro-schlieren setup is employed to characterize the dynamic response of these actuators. The actuators performed at a range of frequencies, 20.3-27.8 and 54.8-78.2 kHz, respectively. In addition to providing information on the actuator flow physics and performance at various operating conditions, this study serves to develop easy-to-integrate high-frequency actuators for active control of high-speed jets. Preliminary testing of these actuators is performed by implementing the 20-kHz actuator on a Mach 0.9 free jet flow field for noise reduction. Acoustic measurements in the jet near field demonstrate attenuation of radiated noise at all observation angles.

  1. Computational Aerodynamic Simulations of a 1484 ft/sec Tip Speed Quiet High-Speed Fan System Model for Acoustic Methods Assessment and Development

    Science.gov (United States)

    Tweedt, Daniel L.

    2014-01-01

    Computational Aerodynamic simulations of a 1484 ft/sec tip speed quiet high-speed fan system were performed at five different operating points on the fan operating line, in order to provide detailed internal flow field information for use with fan acoustic prediction methods presently being developed, assessed and validated. The fan system is a sub-scale, low-noise research fan/nacelle model that has undergone experimental testing in the 9- by 15-foot Low Speed Wind Tunnel at the NASA Glenn Research Center. Details of the fan geometry, the computational fluid dynamics methods, the computational grids, and various computational parameters relevant to the numerical simulations are discussed. Flow field results for three of the five operating points simulated are presented in order to provide a representative look at the computed solutions. Each of the five fan aerodynamic simulations involved the entire fan system, which includes a core duct and a bypass duct that merge upstream of the fan system nozzle. As a result, only fan rotational speed and the system bypass ratio, set by means of a translating nozzle plug, were adjusted in order to set the fan operating point, leading to operating points that lie on a fan operating line and making mass flow rate a fully dependent parameter. The resulting mass flow rates are in good agreement with measurement values. Computed blade row flow fields at all fan operating points are, in general, aerodynamically healthy. Rotor blade and fan exit guide vane flow characteristics are good, including incidence and deviation angles, chordwise static pressure distributions, blade surface boundary layers, secondary flow structures, and blade wakes. Examination of the computed flow fields reveals no excessive or critical boundary layer separations or related secondary-flow problems, with the exception of the hub boundary layer at the core duct entrance. At that location a significant flow separation is present. The region of local flow

  2. On the reversed Brayton cycle with high speed machinery

    Energy Technology Data Exchange (ETDEWEB)

    Backman, J.

    1996-12-31

    This work was carried out in the laboratory of Fluid Dynamics, at Lappeenranta University of Technology during the years 1991-1996. The research was a part of larger high speed technology development research. First, there was the idea of making high speed machinery applications with the Brayton cycle. There was a clear need to deepen the knowledge of the cycle itself and to make a new approach in the field of the research. Also, the removal of water from the humid air seemed very interesting. The goal of this work was to study methods of designing high speed machinery for the reversed Brayton cycle, from theoretical principles to practical applications. The reversed Brayton cycle can be employed as an air dryer, a heat pump or a refrigerating machine. In this research the use of humid air as a working fluid has an environmental advantage, as well. A new calculation method for the Brayton cycle is developed. In this method especially the expansion process in the turbine is important because of the condensation of the water vapour in the humid air. This physical phenomena can have significant effects on the level of performance of the application. Also, the influence of calculating the process with actual, achievable process equipment efficiencies is essential for the development of future machinery. The above theoretical calculations are confirmed with two different laboratory prototypes. (53 refs.)

  3. On the reversed Brayton cycle with high speed machinery

    Energy Technology Data Exchange (ETDEWEB)

    Backman, J

    1997-12-31

    This work was carried out in the laboratory of Fluid Dynamics, at Lappeenranta University of Technology during the years 1991-1996. The research was a part of larger high speed technology development research. First, there was the idea of making high speed machinery applications with the Brayton cycle. There was a clear need to deepen the knowledge of the cycle itself and to make a new approach in the field of the research. Also, the removal of water from the humid air seemed very interesting. The goal of this work was to study methods of designing high speed machinery for the reversed Brayton cycle, from theoretical principles to practical applications. The reversed Brayton cycle can be employed as an air dryer, a heat pump or a refrigerating machine. In this research the use of humid air as a working fluid has an environmental advantage, as well. A new calculation method for the Brayton cycle is developed. In this method especially the expansion process in the turbine is important because of the condensation of the water vapour in the humid air. This physical phenomena can have significant effects on the level of performance of the application. Also, the influence of calculating the process with actual, achievable process equipment efficiencies is essential for the development of future machinery. The above theoretical calculations are confirmed with two different laboratory prototypes. (53 refs.)

  4. Double Helical Gear Performance Results in High Speed Gear Trains

    Science.gov (United States)

    Handschuh, Robert F.; Ehinger, Ryan; Sinusas, Eric; Kilmain, Charles

    2010-01-01

    The operation of high speed gearing systems in the transmissions of tiltrotor aircraft has an effect on overall propulsion system efficiency. Recent work has focused on many aspects of high-speed helical gear trains as would be used in tiltrotor aircraft such as operational characteristics, comparison of analytical predictions to experimental data and the affect of superfinishing on transmission performance. Baseline tests of an aerospace quality system have been conducted in the NASA Glenn High-Speed Helical Gear Train Test Facility and have been described in earlier studies. These earlier tests had utilized single helical gears. The results that will be described in this study are those attained using double helical gears. This type of gear mesh can be configured in this facility to either pump the air-oil environment from the center gap between the meshing gears to the outside of tooth ends or in the reverse direction. Tests were conducted with both inward and outward air-oil pumping directions. Results are compared to the earlier baseline results of single helical gears.

  5. High-speed imaging of blood splatter patterns

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, T.E.; Albright, K.A.; King, N.S.P.; Yates, G.J. (Los Alamos National Lab., NM (United States)); Levine, G.F. (California Dept. of Justice, Sacramento, CA (United States). Bureau of Forensic Services)

    1993-01-01

    The interpretation of blood splatter patterns is an important element in reconstructing the events and circumstances of an accident or crime scene. Unfortunately, the interpretation of patterns and stains formed by blood droplets is not necessarily intuitive and study and analysis are required to arrive at a correct conclusion. A very useful tool in the study of blood splatter patterns is high-speed photography. Scientists at the Los Alamos National Laboratory, Department of Energy (DOE), and Bureau of Forensic Services, State of California, have assembled a high-speed imaging system designed to image blood splatter patterns. The camera employs technology developed by Los Alamos for the underground nuclear testing program and has also been used in a military mine detection program. The camera uses a solid-state CCD sensor operating at approximately 650 frames per second (75 MPixels per second) with a microchannel plate image intensifier that can provide shuttering as short as 5 ns. The images are captured with a laboratory high-speed digitizer and transferred to an IBM compatible PC for display and hard copy output for analysis. The imaging system is described in this paper.

  6. High-speed imaging of blood splatter patterns

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, T.E.; Albright, K.A.; King, N.S.P.; Yates, G.J. [Los Alamos National Lab., NM (United States); Levine, G.F. [California Dept. of Justice, Sacramento, CA (United States). Bureau of Forensic Services

    1993-05-01

    The interpretation of blood splatter patterns is an important element in reconstructing the events and circumstances of an accident or crime scene. Unfortunately, the interpretation of patterns and stains formed by blood droplets is not necessarily intuitive and study and analysis are required to arrive at a correct conclusion. A very useful tool in the study of blood splatter patterns is high-speed photography. Scientists at the Los Alamos National Laboratory, Department of Energy (DOE), and Bureau of Forensic Services, State of California, have assembled a high-speed imaging system designed to image blood splatter patterns. The camera employs technology developed by Los Alamos for the underground nuclear testing program and has also been used in a military mine detection program. The camera uses a solid-state CCD sensor operating at approximately 650 frames per second (75 MPixels per second) with a microchannel plate image intensifier that can provide shuttering as short as 5 ns. The images are captured with a laboratory high-speed digitizer and transferred to an IBM compatible PC for display and hard copy output for analysis. The imaging system is described in this paper.

  7. Ping-Pong Robotics with High-Speed Vision System

    DEFF Research Database (Denmark)

    Li, Hailing; Wu, Haiyan; Lou, Lei

    2012-01-01

    The performance of vision-based control is usually limited by the low sampling rate of the visual feedback. We address Ping-Pong robotics as a widely studied example which requires high-speed vision for highly dynamic motion control. In order to detect a flying ball accurately and robustly...... of the manipulator are updated iteratively with decreasing error. Experiments are conducted on a 7 degrees of freedom humanoid robot arm. A successful Ping-Pong playing between the robot arm and human is achieved with a high successful rate of 88%....

  8. Optical fiber imaging for high speed plasma motion diagnostics: Applied to low voltage circuit breakers

    International Nuclear Information System (INIS)

    McBride, J. W.; Balestrero, A.; Tribulato, G.; Ghezzi, L.; Cross, K. J.

    2010-01-01

    An integrated portable measurement system is described for the study of high speed and high temperature unsteady plasma flows such as those found in the vicinity of high current switching arcs. An array of optical fibers allows the formation of low spatial resolution images, with a maximum capture rate of 1x10 6 images per second (1 MHz), with 8 bit intensity resolution. Novel software techniques are reported to allow imaging of the arc; and to measure arc trajectories. Results are presented on high current (2 kA) discharge events in a model test fixture and on the application to a commercial low voltage circuit breaker.

  9. The development of high-speed 100 fps CCD camera

    International Nuclear Information System (INIS)

    Hoffberg, M.; Laird, R.; Lenkzsus, F.; Liu, C.; Rodricks, B.

    1997-01-01

    This paper describes the development of a high-speed CCD digital camera system. The system has been designed to use CCDs from various manufacturers with minimal modifications. The first camera built on this design utilizes a Thomson 512 x 512 pixel CCD as its sensor, which is read out from two parallel outputs at a speed of 15 MHz/pixel/output. The data undergo correlated double sampling after which it is digitized into 12 bits. The throughput of the system translates into 60 MB/second, which is either stored directly in a PC or transferred to a custom-designed VXI module. The PC data acquisition version of the camera can collect sustained data in real time that is limited to the memory installed in the PC. The VXI version of the camera, also controlled by a PC, stores 512 MB of real-time data before it must be read out to the PC disk storage. The uncooled CCD can be used either with lenses for visible light imaging or with a phosphor screen for X-ray imaging. This camera has been tested with a phosphor screen coupled to a fiber-optic face plate for high-resolution, high-speed X-ray imaging. The camera is controlled through a custom event-driven user-friendly Windows package. The pixel clock speed can be changed from 1 to 15 MHz. The noise was measured to be 1.05 bits at a 13.3 MHz pixel clock. This paper will describe the electronics, software, and characterizations that have been performed using both visible and X-ray photons. (orig.)

  10. ECONOMIC REASONING MAXIMUM SLOPE IN DESIGN HIGH-SPEED LINES

    Directory of Open Access Journals (Sweden)

    CHERNYSHOVA O. S.

    2016-04-01

    Full Text Available Raising of problem The worldwide design standards high-speed lines are somewhat different. This is due to several reasons: different levels of design speed, differences of characteristics of rolling stock and, in particular, the features of the design plan and longitudinal profile, that are associated primarily with the conditions of the relief. In the design of high-speed railways in Ukraine should take into account these features and determine what the maximum slope values can be used in difficult conditions, as well as how it will affect the operational and capital costs. Purpose. To determine the optimal design parameters of the longitudinal profile. Conclusion. The results are based not only on technical, but also economic indicators and allow the assessment of the necessary capital expenditures and expected cost of the railway in the future. Analytical dependences, to predict the expected operating costs of the railway, depending on the maximum slope, its length and the total length of the section.

  11. High speed TV-towing system for exploration manganese nodules

    International Nuclear Information System (INIS)

    Hartmann, P.

    1977-12-01

    For the oceanographic, special for the manganese nodules exploration in the deep sea a high speed-TV-towing system is to design on base of existing TV-towing systems to get better efficiency during the exploration phase. It is planned to increase to towing speed at the time of 2 knots up to 6-8 knots. The essential points of developments in this direction are 1) to decrease the hydrodynamical drag of the long towing cable with fairings. 2) To seperate to towing system into two units the passiv controlled towing cable end point 'SEP' with negativ buoyancy (weight) and the activ controlled TV-fish. With this separation it is possible to tow the TV-fish within a defined accuracy parallel to the sea floor without an influence to the overall system. 3) To adapt the TV- and photo stobe light unit for these towing conditions (high speed). 4) To design the control concept, the operating equipment, the energy and data transmission system, the towed body concept, the hydrodynamical calculation of towing phase and the other towed components. The results of this study is the definition of a two body towing system which is able towed by a research vessel to make continously TV-observation of the sea floor in depth down to 6,000 meters. (orig.) [de

  12. Dynamic response of high speed centrifuge for reprocessing plant

    International Nuclear Information System (INIS)

    Rajput, Gaurav; Satish Kumar, V.; Selvaraj, T.; Ananda Rao, S.M.; Ravisankar, A.

    2012-01-01

    The standard for balancing the rotating bowl describes only the details about the selection of balance quality grade and the permissible residual unbalance for different operating speeds. This paper presents the effects of unbalance on the rotating bowl of high speed centrifuge used in reprocessing of spent nuclear fuel. In this study, the residual unbalance is evaluated for different recommended balancing grades in accordance with the ISO 1940. This unbalance mass generates dynamic force which acts on the rotor. The dynamic response of the rotor like displacements and stresses under this dynamic force are studied by numerical simulation. Finally, the effect of residual unbalance on the rotating bowl performance for different balancing grades is discussed. The experimental measurements are also carried out for the case of G 1.0 grade balanced rotating bowl to validate the resonance frequency as well as vibration amplitudes. (author)

  13. Electron curing for high speed paper, film and foil converting

    International Nuclear Information System (INIS)

    Nablo, S.V.; Tripp, E.P.

    1979-01-01

    The status of self-shielded, compact electron processors for flexible web converting applications is reviewed. The uses of these units for a variety of laminating applications are described, with emphasis on the application techniques appropriate for low weight, (1 to 2 gm/m 2 ) 100% convertible adhesives. Performance data for electron cured adhesives with polyester/polyethylene systems is presented and compared with conventional urethane systems. The unique surface features of electron cured gravure coatings applied and cured at high speed are discussed, with reference to both paper and film substrates. An important advantage of electron curing of buried adhesive layers is the process quality control permitted by this 'all-electric' system. The performance characteristics of curing atmosphere control (inerting) for coatings are reviewed. Industrial experience with these processors has shown that effective inerting of coated flexible webs at speeds to 250 m/minute is both practical and economical. (author)

  14. High speed cutting of AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Liwei Lu

    2016-06-01

    Full Text Available Using LBR-370 numerical control lathe, high speed cutting was applied to AZ31 magnesium alloy. The influence of cutting parameters on microstructure, surface roughness and machining hardening were investigated by using the methods of single factor and orthogonal experiment. The results show that the cutting parameters have an important effect on microstructure, surface roughness and machine hardening. The depth of stress layer, roughness and hardening present a declining tendency with the increase of the cutting speed and also increase with the augment of the cutting depth and feed rate. Moreover, we established a prediction model of the roughness, which has an important guidance on actual machining process of magnesium alloy.

  15. FORECASTING OF PASSENGER TRAFFIC UPON IMPLEMENTATION OF HIGH-SPEED RUNNING

    Directory of Open Access Journals (Sweden)

    M. B. Kurhan

    2017-02-01

    Full Text Available Purpose. Forecasting of passenger traffic flows in the future is an essential and integral part of the complex process of designing of high-speed network (HSN. HSN direction and its parameters are determined by the volume of passenger traffic, the estimated value of which depends on the economic performance of the country, as well as the material status of citizens living in HSN concentration area, transport mobility of population, development of competing modes of transport and so on. The purpose of this work is to analyse the existing methods of passenger traffic forecasting, to evaluate errors of the existing models concerning determination of traffic volumes and to specify the scientific approach to the development of high-speed rail transport in Ukraine. Methodology. The existing forecasting methods are reduced to the following ones: Delphi approach, extrapolation method, factor and correlation analysis, simulation method. The method described in this paper is based on scientific approaches such as analysis – a comprehensive and detailed study of various aspects of the known forecasting methods, comparing of existing methods for establishing differences and similarities, as well as deduction – use of general knowledge to get the new particular one. Thus, the unified indicators determined for the country as a whole, such as gross domestic product, national income, total population and others cannot be used to forecast the traffic flow on specific areas of HSN construction. Therefore, it is necessary to move from the overall forecast to traffic volume forecast on particular direction. Findings. The conclusions are derived from the analysis of different approaches and methods of passenger flow forecasting. It is proposed to create typical techniques of traffic flow forecasting using modern mathematical methods that would allow avoiding unreasonable decisions and shortening project development time. The resulting recommendations will help

  16. High resolution and high speed positron emission tomography data acquisition

    International Nuclear Information System (INIS)

    Burgiss, S.G.; Byars, L.G.; Jones, W.F.; Casey, M.E.

    1986-01-01

    High resolution positron emission tomography (PET) requires many detectors. Thus, data collection systems for PET must have high data rates, wide data paths, and large memories to histogram the events. This design uses the VMEbus to cost effectively provide these features. It provides for several modes of operation including real time sorting, list mode data storage, and replay of stored list mode data

  17. Gate Drive For High Speed, High Power IGBTs

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, M.N.; Cassel, R.L.; de Lamare, J.E.; Pappas, G.C.; /SLAC

    2007-06-18

    A new gate drive for high-voltage, high-power IGBTs has been developed for the SLAC NLC (Next Linear Collider) Solid State Induction Modulator. This paper describes the design and implementation of a driver that allows an IGBT module rated at 800A/3300V to switch up to 3000A at 2200V in 3{micro}S with a rate of current rise of more than 10000A/{micro}S, while still being short circuit protected. Issues regarding fast turn on, high de-saturation voltage detection, and low short circuit peak current will be presented. A novel approach is also used to counter the effect of unequal current sharing between parallel chips inside most high-power IGBT modules. It effectively reduces the collector-emitter peak current, and thus protects the IGBT from being destroyed during soft short circuit conditions at high di/dt.

  18. Gate Drive For High Speed, High Power IGBTs

    International Nuclear Information System (INIS)

    Nguyen, M.N.; Cassel, R.L.; de Lamare, J.E.; Pappas, G.C.; SLAC

    2007-01-01

    A new gate drive for high-voltage, high-power IGBTs has been developed for the SLAC NLC (Next Linear Collider) Solid State Induction Modulator. This paper describes the design and implementation of a driver that allows an IGBT module rated at 800A/3300V to switch up to 3000A at 2200V in 3(micro)S with a rate of current rise of more than 10000A/(micro)S, while still being short circuit protected. Issues regarding fast turn on, high de-saturation voltage detection, and low short circuit peak current will be presented. A novel approach is also used to counter the effect of unequal current sharing between parallel chips inside most high-power IGBT modules. It effectively reduces the collector-emitter peak current, and thus protects the IGBT from being destroyed during soft short circuit conditions at high di/dt

  19. High-speed uncooled MWIR hostile fire indication sensor

    Science.gov (United States)

    Zhang, L.; Pantuso, F. P.; Jin, G.; Mazurenko, A.; Erdtmann, M.; Radhakrishnan, S.; Salerno, J.

    2011-06-01

    Hostile fire indication (HFI) systems require high-resolution sensor operation at extremely high speeds to capture hostile fire events, including rocket-propelled grenades, anti-aircraft artillery, heavy machine guns, anti-tank guided missiles and small arms. HFI must also be conducted in a waveband with large available signal and low background clutter, in particular the mid-wavelength infrared (MWIR). The shortcoming of current HFI sensors in the MWIR is the bandwidth of the sensor is not sufficient to achieve the required frame rate at the high sensor resolution. Furthermore, current HFI sensors require cryogenic cooling that contributes to size, weight, and power (SWAP) in aircraft-mounted applications where these factors are at a premium. Based on its uncooled photomechanical infrared imaging technology, Agiltron has developed a low-SWAP, high-speed MWIR HFI sensor that breaks the bandwidth bottleneck typical of current infrared sensors. This accomplishment is made possible by using a commercial-off-the-shelf, high-performance visible imager as the readout integrated circuit and physically separating this visible imager from the MWIR-optimized photomechanical sensor chip. With this approach, we have achieved high-resolution operation of our MWIR HFI sensor at 1000 fps, which is unprecedented for an uncooled infrared sensor. We have field tested our MWIR HFI sensor for detecting all hostile fire events mentioned above at several test ranges under a wide range of environmental conditions. The field testing results will be presented.

  20. Time resolution performance studies of contemporary high speed photomultipliers

    International Nuclear Information System (INIS)

    Leskovar, B.; Lo, C.C.

    1978-01-01

    The time resolution capabilities of prototype microchannel plate and static crossed-field photomultipliers have been investigated. Measurements were made of electron transit time, rise time, time response, single phtoelectron time spread and multiphotoelectron time spread for LEP HR350 proximity focused high gain curved microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. The experimental data have been compared with results obtained with conventionally designed high speed photomultipliers. Descriptions are given of both the measuring techniques and the measuring systems. 16 refs

  1. Time resolution performance studies of contemporary high speed photomultipliers

    International Nuclear Information System (INIS)

    Leskovar, B.; Lo, C.C.

    1977-01-01

    The time resolution capabilities of prototype microchannel plate and static crossed-field photomultipliers have been investigated. Measurements were made of electron transit time, rise time, time response, single photoelectron time spread and multiphotoelectron time spread for LEP HR350 proximity focused high gain curved microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. The experimental data have been compared with results obtained with conventionally designed RCS 8850 and C31024 high speed photomultipliers. Descriptions are given of both the measuring techniques and the measuring systems

  2. Signal Conditioning in Process of High Speed Imaging

    Directory of Open Access Journals (Sweden)

    Libor Hargas

    2015-01-01

    Full Text Available The accuracy of cinematic analysis with camera system depends on frame rate of used camera. Specific case of cinematic analysis is in medical research focusing on microscopic objects moving with high frequencies (cilia of respiratory epithelium. The signal acquired by high speed video acquisition system has very amount of data. This paper describes hardware parts, signal condition and software, which is used for image acquiring thru digital camera, intelligent illumination dimming hardware control and ROI statistic creation. All software parts are realized as virtual instruments.

  3. High-Speed Imaging of Dusty Plasma Instabilities

    International Nuclear Information System (INIS)

    Tawidian, H.; Mikikian, M.; Lecas, T.; Boufendi, L.; Coueedel, L.; Vallee, O.

    2011-01-01

    Dust particles in a plasma acquire negative charges by capturing electrons. If the dust particle density is high, a huge loss of free electrons can trigger unstable behaviors in the plasma. Several types of plasma behaviors are analyzed thanks to a high-speed camera like dust particle growth instabilities (DPGI) and a new phenomenon called plasma spheroids. These small plasma spheroids are about a few mm, have a slightly enhanced luminosity, and are observed in the vicinity of the electrodes. Different behaviors are identified for these spheroids like a rotational motion, or a chaotic regime (fast appearance and disappearance).

  4. High-Speed Imaging of Dusty Plasma Instabilities

    Science.gov (United States)

    Tawidian, H.; Couëdel, L.; Mikikian, M.; Lecas, T.; Boufendi, L.; Vallée, O.

    2011-11-01

    Dust particles in a plasma acquire negative charges by capturing electrons. If the dust particle density is high, a huge loss of free electrons can trigger unstable behaviors in the plasma. Several types of plasma behaviors are analyzed thanks to a high-speed camera like dust particle growth instabilities (DPGI) and a new phenomenon called plasma spheroids. These small plasma spheroids are about a few mm, have a slightly enhanced luminosity, and are observed in the vicinity of the electrodes. Different behaviors are identified for these spheroids like a rotational motion, or a chaotic regime (fast appearance and disappearance).

  5. High-speed atomic force microscopy coming of age

    International Nuclear Information System (INIS)

    Ando, Toshio

    2012-01-01

    High-speed atomic force microscopy (HS-AFM) is now materialized. It allows direct visualization of dynamic structural changes and dynamic processes of functioning biological molecules in physiological solutions, at high spatiotemporal resolution. Dynamic molecular events unselectively appear in detail in an AFM movie, facilitating our understanding of how biological molecules operate to function. This review describes a historical overview of technical development towards HS-AFM, summarizes elementary devices and techniques used in the current HS-AFM, and then highlights recent imaging studies. Finally, future challenges of HS-AFM studies are briefly discussed. (topical review)

  6. High-speed atomic force microscopy coming of age

    Science.gov (United States)

    Ando, Toshio

    2012-02-01

    High-speed atomic force microscopy (HS-AFM) is now materialized. It allows direct visualization of dynamic structural changes and dynamic processes of functioning biological molecules in physiological solutions, at high spatiotemporal resolution. Dynamic molecular events unselectively appear in detail in an AFM movie, facilitating our understanding of how biological molecules operate to function. This review describes a historical overview of technical development towards HS-AFM, summarizes elementary devices and techniques used in the current HS-AFM, and then highlights recent imaging studies. Finally, future challenges of HS-AFM studies are briefly discussed.

  7. High speed photography diagnostics in laser-plasma interaction experiments

    International Nuclear Information System (INIS)

    Andre, M.L.

    1988-01-01

    The authors report on their effort in the development of techniques involved in laser-plasma experiments. This includes not only laser technology but also diagnostics studies and targets design and fabrication. Among the different kind of diagnostics currently used are high speed streak cameras, fast oscilloscopes and detectors sensitive in the i.r., visible, the u.v. region and the x-rays. In this presentation the authors describe the three high power lasers which are still in operation (P 102, OctAL and PHEBUS) and the main diagnostics used to characterize the plasma

  8. Tactile shoe inlays for high speed pressure monitoring

    DEFF Research Database (Denmark)

    Drimus, Alin; Mátéfi-Tempfli, Stefan

    2015-01-01

    This work describes the development of flexible tactile sensor shoe inlays for humanoid robots. Their design is based on a sandwich structure of flexible layers with a thin sheet of piezoresistive rubber as main transducer element. The layout and patterning of top and bottom electrodes give 1024...... pressure sensitive cells and the use of high speed electronics and multiplexing algorithms provides frame rates of 100 Hz. The sensors tolerate overloads while showing a consistent output. The developed prototypes show a high potential not only for robotics, but also for use in sensorised human prosthetics....

  9. MOSS spectroscopic camera for imaging time resolved plasma species temperature and flow speed

    International Nuclear Information System (INIS)

    Michael, Clive; Howard, John

    2000-01-01

    A MOSS (Modulated Optical Solid-State) spectroscopic camera has been devised to monitor the spatial and temporal variations of temperatures and flow speeds of plasma ion species, the Doppler broadening measurement being made of spectroscopic lines specified. As opposed to a single channel MOSS spectrometer, the camera images light from plasma onto an array of light detectors, being mentioned 2D imaging of plasma ion temperatures and flow speeds. In addition, compared to a conventional grating spectrometer, the MOSS camera shows an excellent light collecting performance which leads to the improvement of signal to noise ratio and of time resolution. The present paper first describes basic items of MOSS spectroscopy, then follows MOSS camera with an emphasis on the optical system of 2D imaging. (author)

  10. MOSS spectroscopic camera for imaging time resolved plasma species temperature and flow speed

    Energy Technology Data Exchange (ETDEWEB)

    Michael, Clive; Howard, John [Australian National Univ., Plasma Research Laboratory, Canberra (Australia)

    2000-03-01

    A MOSS (Modulated Optical Solid-State) spectroscopic camera has been devised to monitor the spatial and temporal variations of temperatures and flow speeds of plasma ion species, the Doppler broadening measurement being made of spectroscopic lines specified. As opposed to a single channel MOSS spectrometer, the camera images light from plasma onto an array of light detectors, being mentioned 2D imaging of plasma ion temperatures and flow speeds. In addition, compared to a conventional grating spectrometer, the MOSS camera shows an excellent light collecting performance which leads to the improvement of signal to noise ratio and of time resolution. The present paper first describes basic items of MOSS spectroscopy, then follows MOSS camera with an emphasis on the optical system of 2D imaging. (author)

  11. High-speed and high-fidelity system and method for collecting network traffic

    Science.gov (United States)

    Weigle, Eric H [Los Alamos, NM

    2010-08-24

    A system is provided for the high-speed and high-fidelity collection of network traffic. The system can collect traffic at gigabit-per-second (Gbps) speeds, scale to terabit-per-second (Tbps) speeds, and support additional functions such as real-time network intrusion detection. The present system uses a dedicated operating system for traffic collection to maximize efficiency, scalability, and performance. A scalable infrastructure and apparatus for the present system is provided by splitting the work performed on one host onto multiple hosts. The present system simultaneously addresses the issues of scalability, performance, cost, and adaptability with respect to network monitoring, collection, and other network tasks. In addition to high-speed and high-fidelity network collection, the present system provides a flexible infrastructure to perform virtually any function at high speeds such as real-time network intrusion detection and wide-area network emulation for research purposes.

  12. High-speed and supersonic upward plasma drifts: multi-instrumental study

    Science.gov (United States)

    Astafyeva, E.; Zakharenkova, I.; Hairston, M. R.; Huba, J.; Coley, W. R.

    2017-12-01

    Since the pioneering observations by Aggson et al. (1992, JGR, doi: 10.1002/92JA00644), there have been several reports of the occurrence of high-speed (Vz>800 m/s) and supersonic plasma flows in the post-sunset (e.g., Hysell et al., 1994, JGR, doi: 10.1029/94JA00476; Hanson et al., 1997, JGR, doi: 10.1029/96JA03376) and the pre-dawn sector (Astafyeva and Zakharenkova, 2015, GRL, doi:10.1002/2015GL066369). However, despite this observational evidence, these events remain rare and are not well understood. The main issue is to determine the background conditions leading to the occurrence of these high-speed plasma drifts. In this work, we perform a multi-instrumental study of high-speed and supersonic upward plasma drift events/structures. For this purpose, we analyze data from several ground-based and space-borne instruments, including data from the DMSP, Swarm and C/NOFS (IVM instrument) satellites. In addition to the space-borne instruments, we use data from ground-based GPS-receivers and ionosondes to further investigate the background ionosphere conditions, as well as the effects produced by the plasma bubbles and ionospheric irregularities. Besides the observations, we add the SAMI3/ESF modeling results on plasma bubble simulations and high-speed drifts inside plasma bubbles. TIE-GCM runs (from the CCMC, https://ccmc.gsfc.nasa.gov) are used to define the background atmospheric/ionospheric and electrodynamical conditions leading to the occurrence of the high-speed and supersonic plasma drift events. Our search of events with upward plasma drift exceeding 800 m/s in the data of DMSP for the years 2002-2016 shows that such high-speed events are extremely rare. During this period of time, only 6 events were found, two of them occurred during the recovery phase of a geomagnetic storm, while the other four were detected during geomagnetically quiet conditions. Concerning the generation of such events, our preliminary results show that enhanced electric fields are

  13. Adaptation of superconducting fault current limiter to high-speed reclosing

    International Nuclear Information System (INIS)

    Koyama, T.; Yanabu, S.

    2009-01-01

    Using a high temperature superconductor, we constructed and tested a model superconducting fault current limiter (SFCL). The superconductor might break in some cases because of its excessive generation of heat. Therefore, it is desirable to interrupt early the current that flows to superconductor. So, we proposed the SFCL using an electromagnetic repulsion switch which is composed of a superconductor, a vacuum interrupter and a by-pass coil, and its structure is simple. Duration that the current flow in the superconductor can be easily minimized to the level of less than 0.5 cycle using this equipment. On the other hand, the fault current is also easily limited by large reactance of the parallel coil. There is duty of high-speed reclosing after interrupting fault current in the electric power system. After the fault current is interrupted, the back-up breaker is re-closed within 350 ms. So, the electromagnetic repulsion switch should return to former state and the superconductor should be recovered to superconducting state before high-speed reclosing. Then, we proposed the SFCL using an electromagnetic repulsion switch which employs our new reclosing function. We also studied recovery time of the superconductor, because superconductor should be recovered to superconducting state within 350 ms. In this paper, the recovery time characteristics of the superconducting wire were investigated. Also, we combined the superconductor with the electromagnetic repulsion switch, and we did performance test. As a result, a high-speed reclosing within 350 ms was proven to be possible.

  14. Pseudo-shock waves and their interactions in high-speed intakes

    Science.gov (United States)

    Gnani, F.; Zare-Behtash, H.; Kontis, K.

    2016-04-01

    In an air-breathing engine the flow deceleration from supersonic to subsonic conditions takes places inside the isolator through a gradual compression consisting of a series of shock waves. The wave system, referred to as a pseudo-shock wave or shock train, establishes the combustion chamber entrance conditions, and therefore influences the performance of the entire propulsion system. The characteristics of the pseudo-shock depend on a number of variables which make this flow phenomenon particularly challenging to be analysed. Difficulties in experimentally obtaining accurate flow quantities at high speeds and discrepancies of numerical approaches with measured data have been readily reported. Understanding the flow physics in the presence of the interaction of numerous shock waves with the boundary layer in internal flows is essential to developing methods and control strategies. To counteract the negative effects of shock wave/boundary layer interactions, which are responsible for the engine unstart process, multiple flow control methodologies have been proposed. Improved analytical models, advanced experimental methodologies and numerical simulations have allowed a more in-depth analysis of the flow physics. The present paper aims to bring together the main results, on the shock train structure and its associated phenomena inside isolators, studied using the aforementioned tools. Several promising flow control techniques that have more recently been applied to manipulate the shock wave/boundary layer interaction are also examined in this review.

  15. Application of high speed machining technology in aviation

    Science.gov (United States)

    Bałon, Paweł; Szostak, Janusz; Kiełbasa, Bartłomiej; Rejman, Edward; Smusz, Robert

    2018-05-01

    Aircraft structures are exposed to many loads during their working lifespan. Every particular action made during a flight is composed of a series of air movements which generate various aircraft loads. The most rigorous requirement which modern aircraft structures must fulfill is to maintain their high durability and reliability. This requirement involves taking many restrictions into account during the aircraft design process. The most important factor is the structure's overall mass, which has a crucial impact on both utility properties and cost-effectiveness. This makes aircraft one of the most complex results of modern technology. Additionally, there is currently an increasing utilization of high strength aluminum alloys, which requires the implementation of new manufacturing processes. High Speed Machining technology (HSM) is currently one of the most important machining technologies used in the aviation industry, especially in the machining of aluminium alloys. The primary difference between HSM and other milling techniques is the ability to select cutting parameters - depth of the cut layer, feed rate, and cutting speed in order to simultaneously ensure high quality, precision of the machined surface, and high machining efficiency, all of which shorten the manufacturing process of the integral components. In this paper, the authors explain the implementation of the HSM method in integral aircraft constructions. It presents the method of the airframe manufacturing method, and the final results. The HSM method is compared to the previous method where all subcomponents were manufactured by bending and forming processes, and then, they were joined by riveting.

  16. High speed friction microscopy and nanoscale friction coefficient mapping

    International Nuclear Information System (INIS)

    Bosse, James L; Lee, Sungjun; Huey, Bryan D; Andersen, Andreas Sø; Sutherland, Duncan S

    2014-01-01

    As mechanical devices in the nano/micro length scale are increasingly employed, it is crucial to understand nanoscale friction and wear especially at technically relevant sliding velocities. Accordingly, a novel technique has been developed for friction coefficient mapping (FCM), leveraging recent advances in high speed AFM. The technique efficiently acquires friction versus force curves based on a sequence of images at a single location, each with incrementally lower loads. As a result, true maps of the coefficient of friction can be uniquely calculated for heterogeneous surfaces. These parameters are determined at a scan velocity as fast as 2 mm s −1 for microfabricated SiO 2 mesas and Au coated pits, yielding results that are identical to traditional speed measurements despite being ∼1000 times faster. To demonstrate the upper limit of sliding velocity for the custom setup, the friction properties of mica are reported from 200 µm s −1 up to 2 cm s −1 . While FCM is applicable to any AFM and scanning speed, quantitative nanotribology investigations of heterogeneous sliding or rolling components are therefore uniquely possible, even at realistic velocities for devices such as MEMS, biological implants, or data storage systems. (paper)

  17. Super high-speed magnetically levitated system approaches practical use

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Shoji; Nakao, Hiroyuki; Takemasa, Hisashi

    1988-10-01

    The JR-MAGLEV, a super high-speed magnetically levitated system, has been under development since the inauguration with the manufacturing of a succession of trial vehicles. In 1987, the trial vehicle recorded a speed of 400 km/hr as a 2-car formation with passengers. As a participant in the Maglev project, Toshiba has been contributing to the development of superconducting magnets, the main element of the system, as well as auxiliary power sources and the cycloconverter to be used in the substations. A prototype vehicle for commercial service, MLU 002, was manufactured in March 1988 and is now under testing with the aim of achieving a target speed of 420km/hr. The main parameters of superconducting magnet are as follows; magnetomotive force of 700 kA and number of coils of 3 poles/2 trains/ 2 cars, and the magnets are light weight which is almost the limits with the weight ratio to rolling stock of 0.25. As measures to protect vaporization loss of helium for coil-cooling, a relicfaction process of the helium vapor by use of Claude cycle refrigerator was adopted. A circulating current cycloconverter with 16 MVA was developed for the travel motion. The cycloconverter enabled to receive power directly from an electric power company, the output current becomes complete sine wave, and the problems on traveling control were solved. 6 references, 8 figures, 3 tables.

  18. High speed superconducting flywheel system for energy storage

    Science.gov (United States)

    Bornemann, H. J.; Urban, C.; Boegler, P.; Ritter, T.; Zaitsev, O.; Weber, K.; Rietschel, H.

    1994-12-01

    A prototype of a flywheel system with auto stable high temperature superconducting bearings was built and tested. The bearings offered good vertical and lateral stability. A metallic flywheel disk, ø 190 mm x 30 mm, was safely rotated at speeds up to 15000 rpm. The disk was driven by a 3 phase synchronous homopolar motor/generator. Maximum energy capacity was 3.8 Wh, maximum power was 1.5 KW. The dynamic behavior of the prototype was tested, characterized and evaluated with respect to axial and lateral stiffness, decay torques (bearing drag), vibrational modes and critical speeds. The bearings supports a maximum weight of 65 N at zero gap, axial and lateral stiffness at 1 mm gap were 440 N/cm and 130 N/cm, respectively. Spin down experiments were performed to investigate the energy efficiency of the system. The decay rate was found to depend upon background pressure in the vacuum chamber and upon the gap width in the bearing. At a background pressure of 5x10 -4 Torr, the coefficient of friction (drag-to-lift ratio) was measured to be 0.000009 at low speeds for 6 mm gap width in the bearing. Our results indicate that further refinement of this technology will allow operation of higly efficient superconducting flywheels in the kWh range.

  19. High speed laser cutting machine. Kosoku reza kakoki

    Energy Technology Data Exchange (ETDEWEB)

    Shinno, N. (Matsushita Electric Industrial Co. Ltd., Kadoma, Osaka (Japan))

    1993-11-01

    The carbon dioxide gas laser cutting machine is being used widely for from cutting soft steel and stainless steel, etc. to intermetallic welding and in the field of cutting in particular, concerning sheet cutting, it has been changing the existing monopoly of the turret punch press, and as for medium and thick plate cutting, that of the gas plasma fusing device. This article is the general description of high speed laser cutting machine. Concerning the laser cutting (sheet cutting in particular), as the essential items for securing severe cutting accuracy and, at the same time, improving the cutting speed, the following matters are picked up for respective explanation; improvement of stationary machine accuracy, improvement of dynamic machine accuracy, improvement of quality of laser beam as well as optimization of cutting conditions, and shortening of piercing time. Also explanation is given to the respective items, namely speeding-up of medium and thick plate cutting, and reduction of load onto the operator by improved operation. Finally, feeding and removing of a sheet only, and feeding and removing with a pallet are mentioned as the efforts for automation and energy saving. 3 figs., 1 tab.

  20. A transport layer protocol for the future high speed grid computing: SCTP versus fast tcp multihoming

    International Nuclear Information System (INIS)

    Arshad, M.J.; Mian, M.S.

    2010-01-01

    TCP (Transmission Control Protocol) is designed for reliable data transfer on the global Internet today. One of its strong points is its use of flow control algorithm that allows TCP to adjust its congestion window if network congestion is occurred. A number of studies and investigations have confirmed that traditional TCP is not suitable for each and every type of application, for example, bulk data transfer over high speed long distance networks. TCP sustained the time of low-capacity and short-delay networks, however, for numerous factors it cannot be capable to efficiently deal with today's growing technologies (such as wide area Grid computing and optical-fiber networks). This research work surveys the congestion control mechanism of transport protocols, and addresses the different issues involved for transferring the huge data over the future high speed Grid computing and optical-fiber networks. This work also presents the simulations to compare the performance of FAST TCP multihoming with SCTP (Stream Control Transmission Protocol) multihoming in high speed networks. These simulation results show that FAST TCP multihoming achieves bandwidth aggregation efficiently and outperforms SCTP multihoming under a similar network conditions. The survey and simulation results presented in this work reveal that multihoming support into FAST TCP does provide a lot of benefits like redundancy, load-sharing and policy-based routing, which largely improves the whole performance of a network and can meet the increasing demand of the future high-speed network infrastructures (such as in Grid computing). (author)