Science.gov

Sample records for air velocity vector

  1. Application of Vectors to Relative Velocity

    ERIC Educational Resources Information Center

    Tin-Lam, Toh

    2004-01-01

    The topic 'relative velocity' has recently been introduced into the Cambridge Ordinary Level Additional Mathematics syllabus under the application of Vectors. In this note, the results of relative velocity and the 'reduction to rest' technique of teaching relative velocity are derived mathematically from vector algebra, in the hope of providing…

  2. Air-to-Air Missile Vector Scoring

    DTIC Science & Technology

    2012-03-22

    different coordinate frame according to rb = Cbar a (2.1) 9 where ra is a vector expressed in some arbitrary reference frame a, rb is the same vector...ZSigma = []; 236 % Calculate Sigma Point Locations x mean = x minus(:,i+1); P chol = chol (P minus(:,:,i+1))’ XSigma0 = x mean; 241 XSigmai = x mean*ones...1,2*NS)+sqrt(scaling value)*[P chol −P chol ]; XSigma = [XSigma0 XSigmai]; % Calculate Transformed Sigma Points % Sensor 1 246 if detect(1)==1 closest

  3. Air Velocity Mapping of Environmental Test Chambers

    DTIC Science & Technology

    1989-07-01

    variable that must be measured for the evaluations of the air diffusion performance index (ADPI), or the thermal comfort indices such as predicted mean...altered. The impact of asymmetrical airflow patterns undoubtedly affect human thermal comfort votes. The standardized 6 technique described in this...report could be easily employed prior to or along with specific studies requiring precise air velocity data, and coupled with human thermal comfort surveys

  4. The Local Stellar Velocity Field via Vector Spherical Harmonics

    NASA Technical Reports Server (NTRS)

    Makarov, V. V.; Murphy, D. W.

    2007-01-01

    We analyze the local field of stellar tangential velocities for a sample of 42,339 nonbinary Hipparcos stars with accurate parallaxes, using a vector spherical harmonic formalism.We derive simple relations between the parameters of the classical linear model (Ogorodnikov-Milne) of the local systemic field and low-degree terms of the general vector harmonic decomposition. Taking advantage of these relationships, we determine the solar velocity with respect to the local stars of (V(sub X), V(sub Y), V(sub Z)) = (10.5, 18.5, 7.3) +/- 0.1 km s(exp -1) not for the asymmetric drift with respect to the local standard of rest. If only stars more distant than 100 pc are considered, the peculiar solar motion is (V(sub X), V(sub Y), V(sub Z)) = (9.9, 15.6, 6.9) +/- 0.2 km s(exp -1). The adverse effects of harmonic leakage, which occurs between the reflex solar motion represented by the three electric vector harmonics in the velocity space and higher degree harmonics in the proper-motion space, are eliminated in our analysis by direct subtraction of the reflex solar velocity in its tangential components for each star...

  5. Kinematics and aerodynamics of the velocity vector roll

    NASA Technical Reports Server (NTRS)

    Durham, Wayne C.; Lutze, Frederick H.; Mason, W.

    1993-01-01

    The velocity vector roll is an angular rotation of an aircraft about its instantaneous velocity vector, constrained to be performed at constant angle-of-attack (AOA), no sideslip, and constant velocity. Consideration of the aerodynamic force equations leads to requirements for body-axis yawing and pitching rotations that satisfy these constraints. Here, the body axis rotations, and the constraints, are used in the moment equations to determine the aerodynamic moments required to perform the velocity vector roll. For representative tactical aircraft, the conditions for maximum pitching moment are a function of orientation, occurring at about 90 deg of bank in a level trajectory. Maximum required pitching moment occurs at peak roll rate, and is achieved at AOA above 45 deg. The conditions for maximum rolling moment depend on the value of the roll mode time constant. For a small time constant (fast response) the maximum rolling moment occurs at maximum roll acceleration and zero AOA, largely independent of aircraft orientation; for a large time constant, maximum required rolling moment occurs at maximum roll rate, at maximum AOA, and at 180 deg of bank in level flight. Maximum yawing moment occurs at maximum roll acceleration, maximum AOA, and is largely independent of airplane orientation.

  6. Air velocity distribution in a commercial broiler house

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increasing air velocity during tunnel ventilation in commercial broiler production facilities improves production efficiency, and many housing design specifications require a minimum air velocity. Air velocities are typically assessed with a hand-held velocity meter at random locations, rather than ...

  7. Velocity envelope of vector flow estimation with spatial quadrature

    NASA Astrophysics Data System (ADS)

    Kerr, Richard F.; Anderson, Martin E.

    2003-05-01

    We present the results of two studies investigating the optimal aperture configuration for maximized lateral blood flow velocity estimation using Heterodyned Spatial Quadrature. Our objective was to determine the maximum velocities that can be estimated at Doppler angles of 90 degrees and 60 degrees with a bias of less than 5% for both uniform scatterer motion in a tissue-mimicking phantom and blood-mimicking fluid circulated through a wall-less vessel flow phantom. Constant flow rates ranging from 3.0 to 18.0 ml/sec were applied in the flow phantom, producing expected peak velocities of 15.0 to 89.8 cm/sec under laminar flow conditions. Velocity estimates were obtained at each flow rate using 256 trials, with each trial consisting of an ensemble of 32 vectors. For an f/1 receive geometry with bi-lobed Hamming apodization, all peak flow velocities tested were estimated to within 5% of their expected values for both 90 degree and 60 degree Doppler angles. An f/2 receive geometry featuring bi-lobed Blackman apodization generally provided accurate lateral velocity estimates up to 71.9 cm/sec for a Doppler angle of 90 degrees, and accurate lateral component estimates up to 50.1 cm/sec for a 60 degree Doppler angle. The implications of these findings will be discussed.

  8. Optimum instantaneous impulsive orbital injection to attain a specified asymptotic velocity vector.

    NASA Technical Reports Server (NTRS)

    Bean, W. C.

    1971-01-01

    A nalysis of the necessary conditions of Battin for instantaneous orbital injection, with consideration of the uniqueness of his solution, and of the further problem which arises in the degenerate case when radius vector and asymptotic vector are separated by 180 deg. It is shown that when the angular separation between radius vector and asymptotic velocity vector satisfies theta not equal to 180 deg, there are precisely two insertion-velocity vectors which permit attainment of the target asymptotic velocity vector, one yielding posigrade, the other retrograde motion. When theta equals to 180 deg, there is a family of insertion-velocity vectors which permit attainment of a specified asymptotic velocity vector with a unique insertion-velocity vector for every arbitrary orientation of a target unit angular momentum vector.

  9. The Local Stellar Velocity Field via Vector Spherical Harmonics

    NASA Astrophysics Data System (ADS)

    Makarov, V. V.; Murphy, D. W.

    2007-07-01

    We analyze the local field of stellar tangential velocities for a sample of 42,339 nonbinary Hipparcos stars with accurate parallaxes, using a vector spherical harmonic formalism. We derive simple relations between the parameters of the classical linear model (Ogorodnikov-Milne) of the local systemic field and low-degree terms of the general vector harmonic decomposition. Taking advantage of these relationships, we determine the solar velocity with respect to the local stars of (VX,VY,VZ)=(10.5,18.5,7.3)+/-0.1 km s-1 not corrected for the asymmetric drift with respect to the local standard of rest. If only stars more distant than 100 pc are considered, the peculiar solar motion is (VX,VY,VZ)=(9.9,15.6,6.9)+/-0.2 km s-1. The adverse effects of harmonic leakage, which occurs between the reflex solar motion represented by the three electric vector harmonics in the velocity space and higher degree harmonics in the proper-motion space, are eliminated in our analysis by direct subtraction of the reflex solar velocity in its tangential components for each star. The Oort parameters determined by a straightforward least-squares adjustment in vector spherical harmonics are A=14.0+/-1.4, B=-13.1+/-1.2, K=1.1+/-1.8, and C=-2.9+/-1.4 km s-1 kpc-1. The physical meaning and the implications of these parameters are discussed in the framework of a general linear model of the velocity field. We find a few statistically significant higher degree harmonic terms that do not correspond to any parameters in the classical linear model. One of them, a third-degree electric harmonic, is tentatively explained as the response to a negative linear gradient of rotation velocity with distance from the Galactic plane, which we estimate at ~-20 km s-1 kpc-1. A similar vertical gradient of rotation velocity has been detected for more distant stars representing the thick disk (z>1 kpc), but here we surmise its existence in the thin disk at z<200 pc. The most unexpected and unexplained term within

  10. The Local Stellar Velocity Field via Vector Spherical Harmonics

    NASA Technical Reports Server (NTRS)

    Markarov, V. V.; Murphy, D. W.

    2007-01-01

    We analyze the local field of stellar tangential velocities for a sample of 42,339 nonbinary Hipparcos stars with accurate parallaxes, using a vector spherical harmonic formalism. We derive simple relations between the parameters of the classical linear model (Ogorodnikov-Milne) of the local systemic field and low-degree terms of the general vector harmonic decomposition. Taking advantage of these relationships, we determine the solar velocity with respect to the local stars of (V(sub X), V(sub Y), V(sub Z)) (10.5, 18.5, 7.3) +/- 0.1 km s(exp -1) not corrected for the asymmetric drift with respect to the local standard of rest. If only stars more distant than 100 pc are considered, the peculiar solar motion is (V(sub X), V(sub Y), V(sub Z)) (9.9, 15.6, 6.9) +/- 0.2 km s(exp -1). The adverse effects of harmonic leakage, which occurs between the reflex solar motion represented by the three electric vector harmonics in the velocity space and higher degree harmonics in the proper-motion space, are eliminated in our analysis by direct subtraction of the reflex solar velocity in its tangential components for each star. The Oort parameters determined by a straightforward least-squares adjustment in vector spherical harmonics are A=14.0 +/- 1.4, B=13.1 +/- 1.2, K=1.1 +/- 1.8, and C=2.9 +/- 1.4 km s(exp -1) kpc(exp -1). The physical meaning and the implications of these parameters are discussed in the framework of a general linear model of the velocity field. We find a few statistically significant higher degree harmonic terms that do not correspond to any parameters in the classical linear model. One of them, a third-degree electric harmonic, is tentatively explained as the response to a negative linear gradient of rotation velocity with distance from the Galactic plane, which we estimate at approximately -20 km s(exp -1) kpc(exp -1). A similar vertical gradient of rotation velocity has been detected for more distant stars representing the thick disk (z greater than 1 kpc

  11. Volume flow in arteriovenous fistulas using vector velocity ultrasound.

    PubMed

    Hansen, Peter Møller; Olesen, Jacob Bjerring; Pihl, Michael Johannes; Lange, Theis; Heerwagen, Søren; Pedersen, Mads Møller; Rix, Marianne; Lönn, Lars; Jensen, Jørgen Arendt; Nielsen, Michael Bachmann

    2014-11-01

    Volume flow in arteriovenous fistulas for hemodialysis was measured using the angle-independent ultrasound technique Vector Flow Imaging and compared with flow measurements using the ultrasound dilution technique during dialysis. Using an UltraView 800 ultrasound scanner (BK Medical, Herlev, Denmark) with a linear transducer, 20 arteriovenous fistulas were scanned directly on the most superficial part of the fistula just before dialysis. Vector Flow Imaging volume flow was estimated with two different approaches, using the maximum and the average flow velocities detected in the fistula. Flow was estimated to be 242 mL/min and 404 mL/min lower than the ultrasound dilution technique estimate, depending on the approach. The standard deviations of the two Vector Flow Imaging approaches were 175.9 mL/min and 164.8 mL/min compared with a standard deviation of 136.9 mL/min using the ultrasound dilution technique. The study supports that Vector Flow Imaging is applicable for volume flow measurements.

  12. 30 CFR 75.326 - Mean entry air velocity.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Mean entry air velocity. 75.326 Section 75.326... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.326 Mean entry air velocity. In exhausting face ventilation systems, the mean entry air velocity shall be at least 60 feet per...

  13. 30 CFR 75.326 - Mean entry air velocity.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... concentrations in accordance with the applicable levels. Mean entry air velocity shall be determined at or near... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Mean entry air velocity. 75.326 Section 75.326... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.326 Mean entry air velocity....

  14. 30 CFR 75.326 - Mean entry air velocity.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... concentrations in accordance with the applicable levels. Mean entry air velocity shall be determined at or near... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Mean entry air velocity. 75.326 Section 75.326... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.326 Mean entry air velocity....

  15. 30 CFR 75.326 - Mean entry air velocity.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... concentrations in accordance with the applicable levels. Mean entry air velocity shall be determined at or near... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Mean entry air velocity. 75.326 Section 75.326... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.326 Mean entry air velocity....

  16. 30 CFR 75.326 - Mean entry air velocity.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... concentrations in accordance with the applicable levels. Mean entry air velocity shall be determined at or near... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Mean entry air velocity. 75.326 Section 75.326... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.326 Mean entry air velocity....

  17. Phased-array vector velocity estimation using transverse oscillations.

    PubMed

    Pihl, Michael J; Marcher, Jonne; Jensen, Jorgen A

    2012-12-01

    A method for estimating the 2-D vector velocity of blood using a phased-array transducer is presented. The approach is based on the transverse oscillation (TO) method. The purposes of this work are to expand the TO method to a phased-array geometry and to broaden the potential clinical applicability of the method. A phased-array transducer has a smaller footprint and a larger field of view than a linear array, and is therefore more suited for, e.g., cardiac imaging. The method relies on suitable TO fields, and a beamforming strategy employing diverging TO beams is proposed. The implementation of the TO method using a phased-array transducer for vector velocity estimation is evaluated through simulation and flow-rig measurements are acquired using an experimental scanner. The vast number of calculations needed to perform flow simulations makes the optimization of the TO fields a cumbersome process. Therefore, three performance metrics are proposed. They are calculated based on the complex TO spectrum of the combined TO fields. It is hypothesized that the performance metrics are related to the performance of the velocity estimates. The simulations show that the squared correlation values range from 0.79 to 0.92, indicating a correlation between the performance metrics of the TO spectrum and the velocity estimates. Because these performance metrics are much more readily computed, the TO fields can be optimized faster for improved velocity estimation of both simulations and measurements. For simulations of a parabolic flow at a depth of 10 cm, a relative (to the peak velocity) bias and standard deviation of 4% and 8%, respectively, are obtained. Overall, the simulations show that the TO method implemented on a phased-array transducer is robust with relative standard deviations around 10% in most cases. The flow-rig measurements show similar results. At a depth of 9.5 cm using 32 emissions per estimate, the relative standard deviation is 9% and the relative bias is -9

  18. Mathematical Relationships Between Two Sets of Laser Anemometer Measurements for Resolving the Total Velocity Vector

    NASA Technical Reports Server (NTRS)

    Owen, Albert K.

    1993-01-01

    The mathematical relations between the measured velocity fields for the same compressor rotor flow field resolved by two fringe type laser anemometers at different observational locations are developed in this report. The relations allow the two sets of velocity measurements to be combined to produce a total velocity vector field for the compressor rotor. This report presents the derivation of the mathematical relations, beginning with the specification of the coordinate systems and the velocity projections in those coordinate systems. The vector projections are then transformed into a common coordinate system. The transformed vector coordinates are then combined to determine the total velocity vector. A numerical example showing the solution procedure is included.

  19. Experimental analysis of the velocity field of the air flowing through the swirl diffusers

    NASA Astrophysics Data System (ADS)

    Jaszczur, M.; Branny, M.; Karch, M.; Borowski, M.

    2016-09-01

    The article presents the results of experimental studies of flow of air through diffusers. Presented laboratory model is a simplification of the real system and was made in a geometric scale 1:10. Simplifying refer both to the geometry of the object and conditions of air flow. The aim of the study is to determine the actual velocity fields of air flowing out of the swirl diffuser. The results obtained for the diffuser various settings are presented. We have tested various flow rates of air. Stereo Particle Image Velocimetry (SPIV) method was used to measure all velocity vector components. The experimental results allow to determine the actual penetration depth of the supply air into the room. This will allow for better definition of the conditions of ventilation in buildings.

  20. Simulation of air velocity in a vertical perforated air distributor

    NASA Astrophysics Data System (ADS)

    Ngu, T. N. W.; Chu, C. M.; Janaun, J. A.

    2016-06-01

    Perforated pipes are utilized to divide a fluid flow into several smaller streams. Uniform flow distribution requirement is of great concern in engineering applications because it has significant influence on the performance of fluidic devices. For industrial applications, it is crucial to provide a uniform velocity distribution through orifices. In this research, flow distribution patterns of a closed-end multiple outlet pipe standing vertically for air delivery in the horizontal direction was simulated. Computational Fluid Dynamics (CFD), a tool of research for enhancing and understanding design was used as the simulator and the drawing software SolidWorks was used for geometry setup. The main purpose of this work is to establish the influence of size of orifices, intervals between outlets, and the length of tube in order to attain uniformity of exit flows through a multi outlet perforated tube. However, due to the gravitational effect, the compactness of paddy increases gradually from top to bottom of dryer, uniform flow pattern was aimed for top orifices and larger flow for bottom orifices.

  1. Velocity Estimate Following Air Data System Failure

    DTIC Science & Technology

    2008-03-01

    12 Figure 2.2. Pitot Tube...that relay pitot -static information from the aircraft’s air data system and inertial measurement information from the Inertial Navigation System...Air data systems receive total and static pressure inputs from a pitot -static system. A typical pitot tube, as shown below, receives total pressure

  2. Optimization of an algorithm for measurements of velocity vector components using a three-wire sensor.

    PubMed

    Ligeza, P; Socha, K

    2007-10-01

    Hot-wire measurements of velocity vector components use a sensor with three orthogonal wires, taking advantage of an anisotropic effect of wire sensitivity. The sensor is connected to a three-channel anemometric circuit and a data acquisition and processing system. Velocity vector components are obtained from measurement signals, using a modified algorithm for measuring velocity vector components enabling the minimization of measurement errors described in this paper. The standard deviation of the relative error was significantly reduced in comparison with the classical algorithm.

  3. Navigation Doppler Lidar Sensor for Precision Altitude and Vector Velocity Measurements Flight Test Results

    NASA Technical Reports Server (NTRS)

    Pierrottet, Diego F.; Lockhard, George; Amzajerdian, Farzin; Petway, Larry B.; Barnes, Bruce; Hines, Glenn D.

    2011-01-01

    An all fiber Navigation Doppler Lidar (NDL) system is under development at NASA Langley Research Center (LaRC) for precision descent and landing applications on planetary bodies. The sensor produces high resolution line of sight range, altitude above ground, ground relative attitude, and high precision velocity vector measurements. Previous helicopter flight test results demonstrated the NDL measurement concepts, including measurement precision, accuracies, and operational range. This paper discusses the results obtained from a recent campaign to test the improved sensor hardware, and various signal processing algorithms applicable to real-time processing. The NDL was mounted in an instrumentation pod aboard an Erickson Air-Crane helicopter and flown over vegetation free terrain. The sensor was one of several sensors tested in this field test by NASA?s Autonomous Landing and Hazard Avoidance Technology (ALHAT) project.

  4. Air velocity distributions inside tree canopies from a variable-rate air-assisted sprayer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A variable-rate, air assisted, five-port sprayer had been in development to achieve variable discharge rates of both liquid and air. To verify the variable air rate capability by changing the fan inlet diameter of the sprayer, air jet velocities impeded by plant canopies were measured at various loc...

  5. Measurement of rectus femoris muscle velocities during patellar tendon jerk using vector tissue doppler imaging.

    PubMed

    Sikdar, Siddhartha; Lebiedowska, Maria; Eranki, Avinash; Garmirian, Lindsay; Damiano, Diane

    2009-01-01

    We have developed a vector tissue Doppler imaging (TDI) system based on a clinical scanner that can be used to measure muscle velocities independent of the direction of motion. This method overcomes the limitations of conventional Doppler ultrasound, which can only measure velocity components along the ultrasound beam. In this study, we utilized this method to investigate the rectus femoris muscle velocities during a patellar tendon jerk test. Our goal was to investigate whether the muscle elongation velocities during a brisk tendon tap fall within the normal range of velocities that are expected due to rapid stretch of limb segments. In a preliminary study, we recruited six healthy volunteers (three men and three women) following informed consent. The stretch reflex response to tendon tap was evaluated by measuring: (1) the tapping force using an accelerometer instrumented to the neurological hammer (2) the angular velocities of the knee extension and flexion using a electrogoniometer (3) reflex activation using electromyography (EMG) and (4) muscle elongation, extension and flexion velocities using vector TDI. The passive joint angular velocity was linearly related to the passive muscle elongation velocity (R(2)=0.88). The maximum estimated joint angular velocity corresponding to muscle elongation due to tendon tap was less than 8.25 radians/s. This preliminary study demonstrates the feasibility of vector TDI for measuring longitudinal muscle velocities and indicates that the muscle elongation velocities during a clinical tendon tap test are within the normal range of values for rapid limb stretch encountered in daily life. With further refinement, vector TDI could become a powerful method for quantitative evaluation of muscle motion in musculoskeletal disorders.

  6. A Vector Measurement-based Angular Velocity Estimation Scheme for Maneuvering Spacecraft

    NASA Astrophysics Data System (ADS)

    Jo, Sujang; Bang, Hyochoong; Leeghim, Henzeh

    2017-01-01

    A new practical approach to estimate the body angular velocity of maneuvering spacecraft using only vector measurements is presented. Several algorithms have been introduced in previous studies to estimate the angular velocity directly from vector measurements at two time instants. However, these direct methods are based on the constant angular velocity assumption, and estimation results may be invalid for attitude maneuvers. In this paper, an estimation scheme to consider attitude disturbances and control torques is proposed. The effects of angular velocity variation on estimation results are quantitatively evaluated, and an algorithm to minimize estimation errors is designed by selecting the optimal time interval between vector measurements. Without losing the simplicity of direct methods, the design parameters of the algorithm are restricted to the expected covariance of disturbances and the maximum angular acceleration. By applying the proposed estimation scheme, gyroscopes can be directly replaced by attitude sensors such as star trackers.

  7. Velocity vector control system augmented with direct lift control

    NASA Technical Reports Server (NTRS)

    Tisdale, H. F., Sr.; Kelly, W. W. (Inventor)

    1981-01-01

    A pilot-controlled stability control system that employs direct lift control (spoiler control) with elevator control to control the flight path angle of an aircraft is described. A computer on the aircraft generates an elevator control signal and a spoiler control signal, using a pilot-controlled pitch control signal and pitch rate, vertical velocity, roll angle, groundspeed, engine pressure ratio and vertical acceleration signals which are generated on the aircraft. The direct lift control by the aircraft spoilers improves the response of the aircraft flight path angle and provides short term flight path stabilization against environmental disturbances.

  8. Angular velocity estimation from measurement vectors of star tracker.

    PubMed

    Liu, Hai-bo; Yang, Jun-cai; Yi, Wen-jun; Wang, Jiong-qi; Yang, Jian-kun; Li, Xiu-jian; Tan, Ji-chun

    2012-06-01

    In most spacecraft, there is a need to know the craft's angular rate. Approaches with least squares and an adaptive Kalman filter are proposed for estimating the angular rate directly from the star tracker measurements. In these approaches, only knowledge of the vector measurements and sampling interval is required. The designed adaptive Kalman filter can filter out noise without information of the dynamic model and inertia dyadic. To verify the proposed estimation approaches, simulations based on the orbit data of the challenging minisatellite payload (CHAMP) satellite and experimental tests with night-sky observation are performed. Both the simulations and experimental testing results have demonstrated that the proposed approach performs well in terms of accuracy, robustness, and performance.

  9. Development and evaluation of an airplane electronic display format aligned with the inertial velocity vector

    NASA Technical Reports Server (NTRS)

    Steinmetz, G. G.

    1986-01-01

    The development of an electronic primary flight display format aligned with the aircraft velocity vector, a simulation evaluation comparing this format with an electronic attitude-aligned primary flight display format, and a flight evaluation of the velocity-vector-aligned display format are described. Earlier tests in turbulent conditions with the electronic attitude-aligned display format had exhibited unsteadiness. A primary objective of aligning the display format with the velocity vector was to take advantage of a velocity-vector control-wheel steering system to provide steadiness of display during turbulent conditions. Better situational awareness under crosswind conditions was also achieved. The evaluation task was a curved, descending approach with turbulent and crosswind conditions. Primary flight display formats contained computer-drawn perspective runway images and flight-path angle information. The flight tests were conducted aboard the NASA Transport Systems Research Vehicle (TSRV). Comparative results of the simulation and flight tests were principally obtained from subjective commentary. Overall, the pilots preferred the display format aligned with the velocity vector.

  10. Air velocity distributions from a variable-rate air-assisted sprayer for tree applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A capability that implements tree structure to control liquid and air flow rates is the preferential design in the development of variable-rate orchard and nursery sprayers. Air jet velocity distributions from an air assisted, five-port sprayer which was under the development to achieve variable-rat...

  11. New sensor for measurement of low air flow velocity. Phase I final report

    SciTech Connect

    Hashemian, H.M.; Hashemian, M.; Riggsbee, E.T.

    1995-08-01

    The project described here is the Phase I feasibility study of a two-phase program to integrate existing technologies to provide a system for determining air flow velocity and direction in radiation work areas. Basically, a low air flow sensor referred to as a thermocouple flow sensor has been developed. The sensor uses a thermocouple as its sensing element. The response time of the thermocouple is measured using an existing in-situ method called the Loop Current Step Response (LCSR) test. The response time results are then converted to a flow signal using a response time-versus-flow correlation. The Phase I effort has shown that a strong correlation exists between the response time of small diameter thermocouples and the ambient flow rate. As such, it has been demonstrated that thermocouple flow sensors can be used successfully to measure low air flow rates that can not be measured with conventional flow sensors. While the thermocouple flow sensor developed in this project was very successful in determining air flow velocity, determining air flow direction was beyond the scope of the Phase I project. Nevertheless, work was performed during Phase I to determine how the new flow sensor can be used to determine the direction, as well as the velocity, of ambient air movements. Basically, it is necessary to use either multiple flow sensors or move a single sensor in the monitoring area and make flow measurements at various locations sweeping the area from top to bottom and from left to right. The results can then be used with empirical or physical models, or in terms of directional vectors to estimate air flow patterns. The measurements can be made continuously or periodically to update the flow patterns as they change when people and objects are moved in the monitoring area. The potential for using multiple thermocouple flow sensors for determining air flow patterns will be examined in Phase II.

  12. Measurement of tendon velocities using vector tissue Doppler imaging: a feasibility study.

    PubMed

    Eranki, Avinash; Bellini, Lindsey; Prosser, Laura; Stanley, Christopher; Bland, Daniel; Alter, Katharine; Damiano, Diane; Sikdar, Siddhartha

    2010-01-01

    We have developed a vector Doppler ultrasound imaging method to directly quantify the magnitude and direction of muscle and tendon velocities during movement. The goal of this study was to evaluate the feasibility of using vector Tissue Doppler Imaging (vTDI) for estimating the tibialis anterior tendon velocities during dorsiflexion in children with cerebral palsy who have foot drop. Our preliminary results from this study show that tendon velocities estimated using vTDI have a strong linear correlation with the joint angular velocity estimated using a conventional 3D motion capture system. We observed a peak tendon velocity of 5.66±1.45 cm/s during dorsiflexion and a peak velocity of 8.83±2.13 cm/s during the passive relaxation phase of movement. We also obtained repeatable results from the same subject 3 weeks apart. Direct measurements of muscle and tendon velocities may be used as clinical outcome measures and for studying efficiency of movement control.

  13. Measurement of velocity of air flow in the sinus maxillaris.

    PubMed

    Müsebeck, K; Rosenberg, H

    1979-03-01

    Anemometry with the hot wire and hot film technique previously described, enables the rhinologist to record slow and rapidly changing air flow in the maxillary sinus. The advantages and disadvantages of this method are considered. Anemometry together with manometry may be designated sinumetry and used as a diagnostic procedure following sinuscopy in chronic maxillary sinus disease. The value of the function from velocity of time allows the estimation of flow-volume in the sinus. Furthermore, the method is useful to evaluate the optimal therapy to restore ventilation in the case of an obstructed ostium demonstrated before and after surgical opening in the inferior meatus.

  14. Absolute Geostrophic Velocity Inverted from World Ocean Atlas 2013 (WOAV13) with the P-Vector Method

    DTIC Science & Technology

    2015-11-01

    1 WOAV13: world ocean absolute geostrophic velocity Absolute Geostrophic Velocity Inverted from... World Ocean Atlas 2013 (WOAV13) with the P-Vector Method P. C. Chu* and C. W. Fan Naval Ocean Analysis and Prediction (NOAP) Laboratory...from World Ocean Atlas-2013 (WOA13) temperature and salinity fields using the P-vector method. It provides a climatological velocity field that is

  15. Recovering Photospheric Velocities from Vector Magnetograms by Using a Three-dimensional, Fully Magnetohydrodynamic Model

    NASA Astrophysics Data System (ADS)

    Wang, A. H.; Wu, S. T.; Liu, Yang; Hathaway, D.

    2008-02-01

    We use a numerical simulation method for recovering the photospheric velocity field from the vector magnetograms. The traditional method is local correlation tracking (LCT), which is based on measuring the relative displacements of features in blocks of pixels between successive white-light images or magnetograms. Within this method, there are a variety of implementations. One of recently developed implementations is induction local correlation tracking (ILCT) as described by Welsch and coworkers. They employ the normal component of magnetic induction equation as a constraint to assure consistent solutions. Our numerical method uses the fully three-dimensional MHD equations to recover the photospheric velocity field with individual vector magnetograms. We compare our method to the ILCT method using NOAA AR 8210 as an example. The differences and similarities are discussed in detail.

  16. Recovering Photospheric Velocities from Vector Magnetograms by using a Three-Dimensional, Fully Magnetohydrodynamic (MHD) Model

    NASA Technical Reports Server (NTRS)

    Wang, A. H.; Wu, S. T.; Liu, Yang; Hathaway, D.

    2008-01-01

    We introduce a numerical simulation method for recovering the photospheric velocity field from the vector magnetograms. The traditional method is local correlation tracking (LCT) which is based on measuring the relative displacements of features in blocks of pixels between successive white-light images or magnetograms. Within this method, there are a variety of implementations. One of recently developed implementations is induction local correlation tracking (ILCT) as described by Welsch et al. (2004). They employ the normal component of magnetic induction equation as a constraint to assure consistent solutions. Our numerical method uses the fully three-dimensional MHD equations to recover the photospheric velocity field with individual vector magnetograms. We compare our method to the ILCT method using NOAA AR8210 as an example. The differences and similarities are discussed in detail.

  17. Real-time GPU implementation of transverse oscillation vector velocity flow imaging

    NASA Astrophysics Data System (ADS)

    Bradway, David Pierson; Pihl, Michael Johannes; Krebs, Andreas; Tomov, Borislav Gueorguiev; Kjær, Carsten Straso; Nikolov, Svetoslav Ivanov; Jensen, Jørgen Arendt

    2014-03-01

    Rapid estimation of blood velocity and visualization of complex flow patterns are important for clinical use of diagnostic ultrasound. This paper presents real-time processing for two-dimensional (2-D) vector flow imaging which utilizes an off-the-shelf graphics processing unit (GPU). In this work, Open Computing Language (OpenCL) is used to estimate 2-D vector velocity flow in vivo in the carotid artery. Data are streamed live from a BK Medical 2202 Pro Focus UltraView Scanner to a workstation running a research interface software platform. Processing data from a 50 millisecond frame of a duplex vector flow acquisition takes 2.3 milliseconds seconds on an Advanced Micro Devices Radeon HD 7850 GPU card. The detected velocities are accurate to within the precision limit of the output format of the display routine. Because this tool was developed as a module external to the scanner's built-in processing, it enables new opportunities for prototyping novel algorithms, optimizing processing parameters, and accelerating the path from development lab to clinic.

  18. Drift Velocity of Electrons in Hot and Moist Air mixtures

    NASA Astrophysics Data System (ADS)

    Abner, Douglas

    1999-10-01

    The drift velocity of electrons in hot and moist air is presented. The apparatus consisted of a pulsed Townsend-type drift tube with an oil-free vacuum system and employed a temperature controller and heating system to regulate the temperature of the gas mixture and chamber to within 0.1 deg. C. over a range of ambient to 200 deg C. The drift tube is equipped with a movable anode allowing the anode-cathode separation to be varied from 0.8 to 7.4 cm. Water vapor concentration in the air mixture ranged from 0.7510.0Temperature was varied from ambient to 150 deg C. E/N (electric field normalized to gas density) ranged from 1.0 to 16 Td (1 Td = 10-17 V-cm2). Comparisons of data collected at elevated temperature, data collected at ambient temperature, and Boltzmann transport equation calculations show the effects of enhanced rotational and vibrational populations on the drift velocity.

  19. Angular velocity estimation based on star vector with improved current statistical model Kalman filter.

    PubMed

    Zhang, Hao; Niu, Yanxiong; Lu, Jiazhen; Zhang, He

    2016-11-20

    Angular velocity information is a requisite for a spacecraft guidance, navigation, and control system. In this paper, an approach for angular velocity estimation based merely on star vector measurement with an improved current statistical model Kalman filter is proposed. High-precision angular velocity estimation can be achieved under dynamic conditions. The amount of calculation is also reduced compared to a Kalman filter. Different trajectories are simulated to test this approach, and experiments with real starry sky observation are implemented for further confirmation. The estimation accuracy is proved to be better than 10-4  rad/s under various conditions. Both the simulation and the experiment demonstrate that the described approach is effective and shows an excellent performance under both static and dynamic conditions.

  20. Pointing-Vector and Velocity Based Frequency Predicts for Deep-Space Uplink Array Applications

    NASA Technical Reports Server (NTRS)

    Tsao, P.; Vilnrotter, Victor A.; Jamnejad, V.

    2008-01-01

    Uplink array technology is currently being developed for NASA's Deep Space Network (DSN) to provide greater range and data throughput for future NASA missions, including manned missions to Mars and exploratory missions to the outer planets, the Kuiper belt, and beyond. Here we describe a novel technique for generating the frequency predicts that are used to compensate for relative Doppler, derived from interpolated earth position and spacecraft ephemerides. The method described here guarantees velocity and range estimates that are consistent with each other, hence one can always be recovered from the other. Experimental results have recently proven that these frequency predicts are accurate enough to maintain the phase of a three element array at the EPOXI spacecraft for three hours. Previous methods derive frequency predicts directly from interpolated relative velocities. However, these velocities were found to be inconsistent with the corresponding spacecraft range, meaning that range could not always be recovered accurately from the velocity predicts, and vice versa. Nevertheless, velocity-based predicts are also capable of maintaining uplink array phase calibration for extended periods, as demonstrated with the EPOXI spacecraft, however with these predicts important range and phase information may be lost. A comparison of the steering-vector method with velocity-based techniques for generating precise frequency predicts specifically for uplink array applications is provided in the following sections.

  1. Hadoop-Based Distributed System for Online Prediction of Air Pollution Based on Support Vector Machine

    NASA Astrophysics Data System (ADS)

    Ghaemi, Z.; Farnaghi, M.; Alimohammadi, A.

    2015-12-01

    The critical impact of air pollution on human health and environment in one hand and the complexity of pollutant concentration behavior in the other hand lead the scientists to look for advance techniques for monitoring and predicting the urban air quality. Additionally, recent developments in data measurement techniques have led to collection of various types of data about air quality. Such data is extremely voluminous and to be useful it must be processed at high velocity. Due to the complexity of big data analysis especially for dynamic applications, online forecasting of pollutant concentration trends within a reasonable processing time is still an open problem. The purpose of this paper is to present an online forecasting approach based on Support Vector Machine (SVM) to predict the air quality one day in advance. In order to overcome the computational requirements for large-scale data analysis, distributed computing based on the Hadoop platform has been employed to leverage the processing power of multiple processing units. The MapReduce programming model is adopted for massive parallel processing in this study. Based on the online algorithm and Hadoop framework, an online forecasting system is designed to predict the air pollution of Tehran for the next 24 hours. The results have been assessed on the basis of Processing Time and Efficiency. Quite accurate predictions of air pollutant indicator levels within an acceptable processing time prove that the presented approach is very suitable to tackle large scale air pollution prediction problems.

  2. Performance of velocity vector estimation using an improved dynamic beamforming setup

    NASA Astrophysics Data System (ADS)

    Munk, Peter; Jensen, Joergen A.

    2001-05-01

    Estimation of velocity vectors using transverse spatial modulation has previously been presented. Initially, the velocity estimation was improved using an approximated dynamic beamformer setup instead of a static combined with a new velocity estimation scheme. A new beamformer setup for dynamic control of the acoustic field, based on the Pulsed Plane Wave Decomposition (PPWD), is presented. The PPWD gives an unambiguous relation between a given acoustic field and the time functions needed on an array transducer for transmission. Applying this method for the receive beamformation results in a setup of the beamformer with different filters for each channel for each estimation depth. The method of the PPWD is illustrated by analytical expressions of the decomposed acoustic field and these results are used for simulation. Results of velocity estimates using the new setup are given on the basis of simulated and experimental data. The simulation setup is an attempt to approximate the situation present when performing a scanning of the carotid artery with a linear array. Measurement of the flow perpendicular to the emission direction is possible using the approach of transverse spatial modulation. This is most often the case in a scanning of the carotid artery, where the situation is handled by an angled Doppler setup in the present ultrasound scanners. The modulation period of 2 mm is controlled for a range of 20-40 mm which covers the typical range of the carotid artery. A 6 MHz array on a 128-channel system is simulated. The flow setup in the simulation is based on a vessel with a parabolic flow profile for a 60 and 90-degree flow angle. The experimental results are based on the backscattered signal from a sponge mounted in a stepping device. The bias and std. Dev. Of the velocity estimate are calculated for four different flow angles (50,60,75 and 90 degrees). The velocity vector is calculated using the improved 2D estimation approach at a range of depths.

  3. Ultrasonic 3-D Vector Flow Method for Quantitative In Vivo Peak Velocity and Flow Rate Estimation.

    PubMed

    Holbek, Simon; Ewertsen, Caroline; Bouzari, Hamed; Pihl, Michael Johannes; Hansen, Kristoffer Lindskov; Stuart, Matthias Bo; Thomsen, Carsten; Nielsen, Michael Bachmann; Jensen, Jorgen Arendt

    2017-03-01

    Current clinical ultrasound (US) systems are limited to show blood flow movement in either 1-D or 2-D. In this paper, a method for estimating 3-D vector velocities in a plane using the transverse oscillation method, a 32×32 element matrix array, and the experimental US scanner SARUS is presented. The aim of this paper is to estimate precise flow rates and peak velocities derived from 3-D vector flow estimates. The emission sequence provides 3-D vector flow estimates at up to 1.145 frames/s in a plane, and was used to estimate 3-D vector flow in a cross-sectional image plane. The method is validated in two phantom studies, where flow rates are measured in a flow-rig, providing a constant parabolic flow, and in a straight-vessel phantom ( ∅=8 mm) connected to a flow pump capable of generating time varying waveforms. Flow rates are estimated to be 82.1 ± 2.8 L/min in the flow-rig compared with the expected 79.8 L/min, and to 2.68 ± 0.04 mL/stroke in the pulsating environment compared with the expected 2.57 ± 0.08 mL/stroke. Flow rates estimated in the common carotid artery of a healthy volunteer are compared with magnetic resonance imaging (MRI) measured flow rates using a 1-D through-plane velocity sequence. Mean flow rates were 333 ± 31 mL/min for the presented method and 346 ± 2 mL/min for the MRI measurements.

  4. 'Snap-shot' velocity vector mapping using echo-planar imaging.

    PubMed

    Tayler, Alexander B; Sederman, Andrew J; Newling, Benedict; Mantle, Mick D; Gladden, Lynn F

    2010-06-01

    A 'snap-shot' ultra-fast MRI velocimetry technique based upon the echo-planar imaging (EPI) pulse sequence is presented. The new technique is an extension of the GERVAIS pulse sequence previously developed by Sederman et al. (2004) and is capable of acquiring both reference and velocity encoded phase maps following a single excitation for generation of three-component velocity vectors in under 125 ms. This approach allows velocity images of systems with a dynamic, non-periodic geometry to be obtained by MRI. The technique proved to be accurate within 5% error by comparison with Poiseuille flow in a pipe and for the transverse plane flow field in a Couette cell. It was further applied to obtain the velocity field around an impeller in a stirred vessel; an unsteady yet periodic system which otherwise could only be studied by triggered acquisitions. Good agreement was evident between the present technique and triggered conventional velocity encoded pulse sequences. Finally, new experimental data attainable only by the new sequence is demonstrated as the flow field within a mobile droplet of oil is captured as it rises through a column of water. The technique promises to be highly useful in velocimetric measurements of dynamic, non-periodic systems, and in particular for the characterisation of multiphase flow systems.

  5. Underwater patch near-field acoustical holography based on particle velocity and vector hydrophone array

    NASA Astrophysics Data System (ADS)

    Hu, Bo; Yang, DeSen; Li, SiChun; Sun, Yu; Mo, ShiQi; Shi, ShengGuo

    2012-11-01

    One-step patch near-field acoustical holography (PNAH) is a powerful tool for identifying noise sources from the partially known sound pressure field. The acoustical property to be reconstructed on the surface of interest is related to the partially measured pressure on the hologram surface in terms of sampling and bandlimiting matrices, which cost more in computation. A one-step procedure based on measuring of the normal component of the particle velocity is described, including the mathematical formulation. The numerical simulation shows that one-step PNAH based on particle velocity can obtain more accurately reconstructed results and it is also less sensitive to noise than the method based on pressure. These findings are confirmed by an underwater near-field acoustical holography experiment conducted with a vector hydrophone array. The experimental results have illustrated the high performance of one-step PNAH based on particle velocity in the reconstruction of sound field and the advantages of a vector hydrophone array in an underwater near-field measurement.

  6. Egomotion estimation with optic flow and air velocity sensors.

    PubMed

    Rutkowski, Adam J; Miller, Mikel M; Quinn, Roger D; Willis, Mark A

    2011-06-01

    We develop a method that allows a flyer to estimate its own motion (egomotion), the wind velocity, ground slope, and flight height using only inputs from onboard optic flow and air velocity sensors. Our artificial algorithm demonstrates how it could be possible for flying insects to determine their absolute egomotion using their available sensors, namely their eyes and wind sensitive hairs and antennae. Although many behaviors can be performed by only knowing the direction of travel, behavioral experiments indicate that odor tracking insects are able to estimate the wind direction and control their absolute egomotion (i.e., groundspeed). The egomotion estimation method that we have developed, which we call the opto-aeronautic algorithm, is tested in a variety of wind and ground slope conditions using a video recorded flight of a moth tracking a pheromone plume. Over all test cases that we examined, the algorithm achieved a mean absolute error in height of 7% or less. Furthermore, our algorithm is suitable for the navigation of aerial vehicles in environments where signals from the Global Positioning System are unavailable.

  7. 42 CFR 84.140 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Air velocity and noise levels; hoods and helmets... PROTECTIVE DEVICES Supplied-Air Respirators § 84.140 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  8. 42 CFR 84.140 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Air velocity and noise levels; hoods and helmets... PROTECTIVE DEVICES Supplied-Air Respirators § 84.140 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  9. 42 CFR 84.140 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Air velocity and noise levels; hoods and helmets... PROTECTIVE DEVICES Supplied-Air Respirators § 84.140 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  10. 42 CFR 84.140 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Air velocity and noise levels; hoods and helmets... PROTECTIVE DEVICES Supplied-Air Respirators § 84.140 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  11. 42 CFR 84.140 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Air velocity and noise levels; hoods and helmets... PROTECTIVE DEVICES Supplied-Air Respirators § 84.140 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  12. Effect of wind tunnel air velocity on VOC flux rates from CAFO manure and wastewater

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind tunnels and flux chambers are often used to estimate volatile organic compound (VOC) emissions from animal feeding operations (AFOs) without regard to air velocity or sweep air flow rates. Laboratory experiments were conducted to evaluate the effect of wind tunnel air velocity on VOC emission ...

  13. Blood flow velocity vector field reconstruction from dual-beam bidirectional Doppler OCT measurements in retinal veins

    PubMed Central

    Aschinger, Gerold C.; Schmetterer, Leopold; Doblhoff-Dier, Veronika; Leitgeb, Rainer A.; Garhöfer, Gerhard; Gröschl, Martin; Werkmeister, René M.

    2015-01-01

    In this paper, we demonstrate the possibility to reconstruct the actual blood flow velocity vector field in retinal microvessels from dual-beam bidirectional Doppler optical coherence tomography measurements. First, for a better understanding of measured phase patterns, several flow situations were simulated on the basis of the known dual beam measurement geometry. We were able to extract the vector field parameters that determine the measured phase pattern, allowing for the development of an algorithm to reconstruct the velocity vector field from measured phase data. In a next step, measurements were performed at a straight vessel section and at a venous convergence; the obtained phase data were evaluated by means of the new approach. For the straight vessel section, the reconstructed flow velocity vector field yielded a parabolic flow. For the venous convergence, however, the reconstructed vector field deviated from a parabolic profile, but was in very good accordance with the simulated vector field for the given vessel geometry. The proposed algorithm allows predictions of the velocity vector field. Moreover, the algorithm is also sensitive to directional changes of the flow velocity as small as <1°, thereby offering insight in the flow characteristics of the non-Newtonian fluid blood in microvessels. PMID:26137367

  14. Force, Velocity, and Work: The Effects of Different Contexts on Students' Understanding of Vector Concepts Using Isomorphic Problems

    ERIC Educational Resources Information Center

    Barniol, Pablo; Zavala, Genaro

    2014-01-01

    In this article we compare students' understanding of vector concepts in problems with no physical context, and with three mechanics contexts: force, velocity, and work. Based on our "Test of Understanding of Vectors," a multiple-choice test presented elsewhere, we designed two isomorphic shorter versions of 12 items each: a test with no…

  15. Comparison of carotid artery blood velocity measurements by vector and standard Doppler approaches.

    PubMed

    Tortoli, Piero; Lenge, Matteo; Righi, Daniele; Ciuti, Gabriele; Liebgott, Hervé; Ricci, Stefano

    2015-05-01

    Although severely affected by the angle dependency, carotid artery peak systolic velocity measurements are widely used for assessment of stenosis. In this study, blood peak systolic velocities in the common and internal carotid arteries of both healthy volunteers and patients with internal carotid artery stenosis were measured by two vector Doppler (VD) methods and compared with measurements obtained with the conventional spectral Doppler approach. Although the two VD techniques were completely different (using the transmission of focused beams and plane waves, respectively), the measurement results indicate that these techniques are nearly equivalent. The peak systolic velocities measured in 22 healthy common carotid arteries by the two VD techniques were very close (according to Bland-Altman analysis, the average difference was 3.2%, with limits of agreement of ± 8.6%). Application of Bland-Altman analysis to comparison of either VD technique with the spectral Doppler method provided a 21%-25% average difference with ± 13%-15% limits of agreement. Analysis of the results obtained from 15 internal carotid arteries led to similar conclusions, indicating significant overestimation of peak systolic velocity with the spectral Doppler method. Inter- and intra-operator repeatability measurements performed in a group of 8 healthy volunteers provided equivalent results for all of the methods (coefficients of variability in the range 2.7%-6.9%), even though the sonographers were not familiar with the VD methods. The results of this study suggest that the introduction of vector Doppler methods in commercial machines may finally be considered mature and capable of overcoming the angle-dependent overestimation typical of the standard spectral Doppler approach.

  16. Linear FMCW Laser Radar for Precision Range and Vector Velocity Measurements

    NASA Technical Reports Server (NTRS)

    Pierrottet, Diego; Amzajerdian, Farzin; Petway, Larry; Barnes, Bruce; Lockhard, George; Rubio, Manuel

    2008-01-01

    An all fiber linear frequency modulated continuous wave (FMCW) coherent laser radar system is under development with a goal to aide NASA s new Space Exploration initiative for manned and robotic missions to the Moon and Mars. By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing state-of-the-art fiber optic technologies, highly efficient, compact and reliable laser radar suitable for operation in a space environment is being developed. Linear FMCW lidar has the capability of high-resolution range measurements, and when configured into a multi-channel receiver system it has the capability of obtaining high precision horizontal and vertical velocity measurements. Precision range and vector velocity data are beneficial to navigating planetary landing pods to the preselected site and achieving autonomous, safe soft-landing. The all-fiber coherent laser radar has several important advantages over more conventional pulsed laser altimeters or range finders. One of the advantages of the coherent laser radar is its ability to measure directly the platform velocity by extracting the Doppler shift generated from the motion, as opposed to time of flight range finders where terrain features such as hills, cliffs, or slopes add error to the velocity measurement. Doppler measurements are about two orders of magnitude more accurate than the velocity estimates obtained by pulsed laser altimeters. In addition, most of the components of the device are efficient and reliable commercial off-the-shelf fiber optic telecommunication components. This paper discusses the design and performance of a second-generation brassboard system under development at NASA Langley Research Center as part of the Autonomous Landing and Hazard Avoidance (ALHAT) project.

  17. Drop size distribution and air velocity measurements in air assist swirl atomizer sprays

    NASA Technical Reports Server (NTRS)

    Mao, C.-P.; Oechsle, V.; Chigier, N.

    1987-01-01

    Detailed measurements of mean drop size (SMD) and size distribution parameters have been made using a Fraunhofer diffraction particle sizing instrument in a series of sprays generated by an air assist swirl atomizer. Thirty-six different combinations of fuel and air mass flow rates were examined with liquid flow rates up to 14 lbm/hr and atomizing air flow rates up to 10 lbm/hr. Linear relationships were found between SMD and liquid to air mass flow rate ratios. SMD increased with distance downstream along the center line and also with radial distance from the axis. Increase in obscuration with distance downstream was due to an increase in number density of particles as the result of deceleration of drops and an increase in the exposed path length of the laser beam. Velocity components of the atomizing air flow field measured by a laser anemometer show swirling jet air flow fields with solid body rotation in the core and free vortex flow in the outer regions.

  18. 42 CFR 84.1139 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Air velocity and noise levels; hoods and helmets... Efficiency Respirators and Combination Gas Masks § 84.1139 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  19. 42 CFR 84.202 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Air velocity and noise levels; hoods and helmets... PROTECTIVE DEVICES Chemical Cartridge Respirators § 84.202 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  20. 42 CFR 84.1139 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Air velocity and noise levels; hoods and helmets... Efficiency Respirators and Combination Gas Masks § 84.1139 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  1. 42 CFR 84.1139 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Air velocity and noise levels; hoods and helmets... Efficiency Respirators and Combination Gas Masks § 84.1139 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  2. 42 CFR 84.202 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Air velocity and noise levels; hoods and helmets... PROTECTIVE DEVICES Chemical Cartridge Respirators § 84.202 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  3. 42 CFR 84.202 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Air velocity and noise levels; hoods and helmets... PROTECTIVE DEVICES Chemical Cartridge Respirators § 84.202 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  4. 42 CFR 84.1139 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Air velocity and noise levels; hoods and helmets... Efficiency Respirators and Combination Gas Masks § 84.1139 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  5. 42 CFR 84.202 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Air velocity and noise levels; hoods and helmets... PROTECTIVE DEVICES Chemical Cartridge Respirators § 84.202 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  6. 42 CFR 84.202 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Air velocity and noise levels; hoods and helmets... PROTECTIVE DEVICES Chemical Cartridge Respirators § 84.202 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  7. 42 CFR 84.1139 - Air velocity and noise levels; hoods and helmets; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Air velocity and noise levels; hoods and helmets... Efficiency Respirators and Combination Gas Masks § 84.1139 Air velocity and noise levels; hoods and helmets; minimum requirements. Noise levels generated by the respirator will be measured inside the hood or...

  8. Velocity Vector Field Visualization of Flow in Liquid Acquisition Device Channel

    NASA Technical Reports Server (NTRS)

    McQuillen, John B.; Chao, David F.; Hall, Nancy R.; Zhang, Nengli

    2012-01-01

    A capillary flow liquid acquisition device (LAD) for cryogenic propellants has been developed and tested in NASA Glenn Research Center to meet the requirements of transferring cryogenic liquid propellants from storage tanks to an engine in reduced gravity environments. The prototypical mesh screen channel LAD was fabricated with a mesh screen, covering a rectangular flow channel with a cylindrical outlet tube, and was tested with liquid oxygen (LOX). In order to better understand the performance in various gravity environments and orientations at different liquid submersion depths of the screen channel LAD, a series of computational fluid dynamics (CFD) simulations of LOX flow through the LAD screen channel was undertaken. The resulting velocity vector field visualization for the flow in the channel has been used to reveal the gravity effects on the flow in the screen channel.

  9. Calibration of a system for measuring low air flow velocity in a wind tunnel

    NASA Astrophysics Data System (ADS)

    Krach, Andrzej; Kruczkowski, Janusz

    2016-08-01

    This article presents the calibration of a system for measuring air flow velocity in a wind tunnel with a multiple-hole orifice. The comparative method was applied for the calibration. The method consists in equalising the air flow velocity in a test section of the tunnel with that of the hot-wire anemometer probe which should then read zero value. The hot-wire anemometer probe moves reciprocally in the tunnel test section with a constant velocity, aligned and opposite to the air velocity. Air velocity in the tunnel test section is adjusted so that the minimum values of a periodic hot-wire anemometer signal displayed on an oscilloscope screen reach the lowest position (the minimum method). A sinusoidal component can be superimposed to the probe constant velocity. Then, the air flow velocity in the tunnel test section is adjusted so that, when the probe moves in the direction of air flow, only the second harmonic of the periodically variable velocity superimposed on the constant velocity (second harmonic method) remains at the output of the low-pass filter to which the hot-wire anemometer signal, displayed on the oscilloscope screen, is supplied. The velocity of the uniform motion of the hot-wire anemometer probe is measured with a magnetic linear encoder. The calibration of the system for the measurement of low air velocities in the wind tunnel was performed in the following steps: 1. Calibration of the linear encoder for the measurement of the uniform motion velocity of the hot-wire anemometer probe in the test section of the tunnel. 2. Calibration of the system for measurement of low air velocities with a multiple-hole orifice for the velocities of 0.1 and 0.25 m s-1: - (a) measurement of the probe movement velocity setting; - (b) measurement of air velocity in the tunnel test section with comparison according to the second harmonic method; - (c) measurement of air velocity in the tunnel with comparison according to the minimum method. The calibration

  10. On the Divergence of the Velocity Vector in Real-Gas Flow

    NASA Technical Reports Server (NTRS)

    Bellan, Josette

    2009-01-01

    A theoretical study was performed addressing the degree of applicability or inapplicability, to a real gas, of the occasionally stated belief that for an ideal gas, incompressibility is synonymous with a zero or very low Mach number. The measure of compressibility used in this study is the magnitude of the divergence of the flow velocity vector [V(bar) (raised dot) u (where u is the flow velocity)]. The study involves a mathematical derivation that begins with the governing equations of flow and involves consideration of equations of state, thermodynamics, and fluxes of heat, mass, and the affected molecular species. The derivation leads to an equation for the volume integral of (V(bar) (raised dot) u)(sup 2) that indicates contributions of several thermodynamic, hydrodynamic, and species-flux effects to compressibility and reveals differences between real and ideal gases. An analysis of the equation leads to the conclusion that for a real gas, incompressibility is not synonymous with zero or very small Mach number. Therefore, it is further concluded, the contributions to compressibility revealed by the derived equation should be taken into account in simulations of real-gas flows.

  11. The Effect of Solid Admixtures on the Velocity of Motion of a Free Dusty Air Jet

    NASA Technical Reports Server (NTRS)

    Chernov, A. P.

    1957-01-01

    In dusty air flows occurring in industrial practice in transport by air pressure of friable materials, in the drying, annealing, and so forth, of a pulverized solid mass in suspension, and in other processes, the concentration of solid particles usually has a magnitude of the order of 1 kg per 1 kg of air. At such a concentration, the ratio of the volume of the particles to the volume of the air is small (less than one-thousandth part). However, regardless of this, the presence of a solid admixture manifests itself in the rules for the velocity distribution of the air in a dusty air flow. As a result, the rules of velocity change are different for clean and for dusty air flows. The estimation of the influence of the admixture on the velocity of the motion of the flow presents a definitive interest. One of the attempts to estimate that influence on the axial velocity of a free axially symmetrical jet with admixtures was made by Abramovich. Abramovich assumed beforehand that the fine particles of the admixture in the jet are subject to the motion of the air (that is, that the velocity of the admixture is approximately equal to the local velocity of the air); he then took as the basis of his considerations, in solving the problem, the condition that the amount of motion of the two-phase jet must be constant.

  12. Web-based GIS: the vector-borne disease airline importation risk (VBD-AIR) tool

    PubMed Central

    2012-01-01

    Background Over the past century, the size and complexity of the air travel network has increased dramatically. Nowadays, there are 29.6 million scheduled flights per year and around 2.7 billion passengers are transported annually. The rapid expansion of the network increasingly connects regions of endemic vector-borne disease with the rest of the world, resulting in challenges to health systems worldwide in terms of vector-borne pathogen importation and disease vector invasion events. Here we describe the development of a user-friendly Web-based GIS tool: the Vector-Borne Disease Airline Importation Risk Tool (VBD-AIR), to help better define the roles of airports and airlines in the transmission and spread of vector-borne diseases. Methods Spatial datasets on modeled global disease and vector distributions, as well as climatic and air network traffic data were assembled. These were combined to derive relative risk metrics via air travel for imported infections, imported vectors and onward transmission, and incorporated into a three-tier server architecture in a Model-View-Controller framework with distributed GIS components. A user-friendly web-portal was built that enables dynamic querying of the spatial databases to provide relevant information. Results The VBD-AIR tool constructed enables the user to explore the interrelationships among modeled global distributions of vector-borne infectious diseases (malaria. dengue, yellow fever and chikungunya) and international air service routes to quantify seasonally changing risks of vector and vector-borne disease importation and spread by air travel, forming an evidence base to help plan mitigation strategies. The VBD-AIR tool is available at http://www.vbd-air.com. Conclusions VBD-AIR supports a data flow that generates analytical results from disparate but complementary datasets into an organized cartographical presentation on a web map for the assessment of vector-borne disease movements on the air travel network

  13. Estimation of Errors in the Transverse Velocity Vectors Determined from HINODE/SOT Magnetograms Using the NAVE Technique

    NASA Astrophysics Data System (ADS)

    Chae, Jongchul; Moon, Yong-Jae

    2009-06-01

    Transverse velocity vectors can be determined from a pair of images successively taken with a time interval using an optical flow technique. We have tested the performance of the new technique called NAVE (non-linear affine velocity estimator) recently implemented by Chae & Sakurai using real image data taken by the Narrowband Filter Imager (NFI) of the Solar Optical Telescope (SOT) aboard the Hinode satellite. We have developed two methods of estimating the errors in the determination of velocity vectors, one resulting from the non-linear fitting σ_v and the other ɛ_u resulting from the statistics of the determined velocity vectors. The real error is expected to be somewhere between σ_v and ɛ_u. We have investigated the dependence of the determined velocity vectors and their errors on the different parameters such as the critical speed for the subsonic filtering, the width of the localizing window, the time interval between two successive images, and the signal-to-noise ratio of the feature. With the choice of v_{crit}=2 pixel/step for the subsonic filtering, and the window FWHM of 16 pixels, and the time interval of one step (2 minutes), we find that the errors of velocity vectors determined using the NAVE range from around 0.04 pixel/step in high signal-to-noise ratio features (S/N ˜ 10), to 0.1 pixel/step in low signa-to-noise ratio features (S/N ˜ 3) with the mean of about 0.06 pixel/step where 1 pixel/step corresponds roughly to 1 km/s in our case.

  14. Velocity and pressure distribution behind bodies in an air current

    NASA Technical Reports Server (NTRS)

    Betz, A

    1924-01-01

    The following experiments on the air flow behind bodies were made for the purpose of assisting in the explanation of the phenomena connected with air resistance. The first two series of experiments dealt with the phenomena behind a cylinder. The third series of experiments was carried out behind a streamlined strut.

  15. A new test chamber to measure material emissions under controlled air velocity

    SciTech Connect

    Bortoli, M. de; Ghezzi, E.; Knoeppel, H.; Vissers, H.

    1999-05-15

    A new 20-L glass chamber for the determination of VOC emissions from construction materials and consumer products under controlled air velocity and turbulence is described. Profiles of air velocity and turbulence, obtained with precisely positioned hot wire anemometric probes, show that the velocity field is homogeneous and that air velocity is tightly controlled by the fan rotation speed; this overcomes the problem of selecting representative positions to measure air velocity above a test specimen. First tests on material emissions show that the influence of air velocity on the emission rate of VOCs is negligible for sources limited by internal diffusion and strong for sources limited by evaporation. In a velocity interval from 0.15 to 0.30 m s{sup {minus}1}, an emission rate increase of 50% has been observed for pure n-decane and 1,4-dichlorobenzene and of 30% for 1,2-propanediol from a water-based paint. In contrast, no measurable influence of turbulence could be observed during vaporization of 1,4-dichlorobenzene within a 3-fold turbulence interval. Investigations still underway show that the chamber has a high recovery for the heavier VOC (TXIB), even at low concentrations.

  16. Assessment of air velocity sensors for use in animal produciton facilities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ventilation is an integral part of thermal environment control in animal production facilities. Accurately measuring the air velocity distribution within these facilities is cumbersome using the traverse method and a distributed velocity measurement system would reduce the time necessary to perform ...

  17. Simultaneous Measurement of Air Temperature and Humidity Based on Sound Velocity and Attenuation Using Ultrasonic Probe

    NASA Astrophysics Data System (ADS)

    Motegi, Takahiro; Mizutani, Koichi; Wakatsuki, Naoto

    2013-07-01

    In this paper, an acoustic technique for air temperature and humidity measurement in moist air is described. The previous ultrasonic probe can enable the estimation of temperature from sound velocity in dry air by making use of the relationship between sound velocity and temperature. However, temperature measurement using the previous ultrasonic probe is not suitable in moist air because sound velocity also depends on humidity, and the temperature estimated from the sound velocity measured in moist air must be adjusted. Moreover, a method of humidity measurement by using only an ultrasonic probe has not been established. Thus, we focus on sound attenuation, which depends on temperature and humidity. Our proposed technique utilizes two parameters, sound velocity and attenuation, and can measure both temperature and humidity simultaneously. The acoustic technique for temperature and humidity measurement has the advantages that instantaneous temperature and humidity can be measured, and the measurement is not affected by thermal radiation because air itself is used as a sensing element. As an experiment, temperature and humidity are measured in a chamber, and compared with the reference values. The experimental results indicate the achievement of a practical temperature measurement accuracy of within +/-0.5 K in moist air, of which the temperature is 293-308 K and relative humidity (RH) is 50-90% RH, and the simultaneous measurement of temperature and humidity.

  18. Dynamical equations for the vector potential and the velocity potential in incompressible irrotational Euler flows: a refined Bernoulli theorem.

    PubMed

    Ohkitani, Koji

    2015-09-01

    We consider incompressible Euler flows in terms of the stream function in two dimensions and the vector potential in three dimensions. We pay special attention to the case with singular distributions of the vorticity, e.g., point vortices in two dimensions. An explicit equation governing the velocity potentials is derived in two steps. (i) Starting from the equation for the stream function [Ohkitani, Nonlinearity 21, T255 (2009)NONLE50951-771510.1088/0951-7715/21/12/T02], which is valid for smooth flows as well, we derive an equation for the complex velocity potential. (ii) Taking a real part of this equation, we find a dynamical equation for the velocity potential, which may be regarded as a refinement of Bernoulli theorem. In three-dimensional incompressible flows, we first derive dynamical equations for the vector potentials which are valid for smooth fields and then recast them in hypercomplex form. The equation for the velocity potential is identified as its real part and is valid, for example, flows with vortex layers. As an application, the Kelvin-Helmholtz problem has been worked out on the basis the current formalism. A connection to the Navier-Stokes regularity problem is addressed as a physical application of the equations for the vector potentials for smooth fields.

  19. Effects of air velocity on laying hen production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermal conditions play a major role in production efficiency in commercial poultry production. Mitigation of thermal stress can improve productivity, but must be achieved economically. Weather and system design can limit effectiveness of evaporative cooling and increased air movement has been sho...

  20. Using direct numerical simulation to analyze and improve hot-wire probe sensor and array configurations for simultaneous measurement of the velocity vector and the velocity gradient tensor

    NASA Astrophysics Data System (ADS)

    Vukoslavčević, Petar V.; Wallace, James M.

    2013-11-01

    Multi-sensor, hot-wire probes of various configurations have been used for 25 years to simultaneously measure the velocity vector and the velocity gradient tensor in turbulent flows. This is the same period in which direct numerical simulations (DNS) were carried out to investigate these flows. Using the first DNS of a turbulent boundary layer, Moin and Spalart ["Contributions of numerical simulation data bases to the physics, modeling and measurement of turbulence," NASA Technical Memorandum 100022 (1987)] examined, virtually, the performance of a two-sensor X-array probe with the sensors idealized as points in the numerical grid. Subsequently, several investigators have used DNS for similar studies. In this paper we use a highly resolved minimal channel flow DNS, following Jiménez and Moin ["The minimal flow unit in near-wall turbulence," J. Fluid Mech. 225, 213 (1991)], to study the performance of an 11-sensor probe. Our previous studies of this type have indicated that, on balance, a probe of the design described here may provide the most accurate measurements of many of the statistics formed from the velocity vector and the velocity gradient tensor (rms and skewness values of the velocity and vorticity components as well as the Reynolds shear stress and the dissipation and production rates). The results of the present study show that, indeed, the sensor and array configurations of a probe of this design are considerably better than previous designs that have been used, and they are likely to give reasonably satisfactory results for such measurements with a real probe in a real bounded flow.

  1. Performance of a combined three-hole conductivity probe for void fraction and velocity measurement in air-water flows

    NASA Astrophysics Data System (ADS)

    Borges, João Eduardo; Pereira, Nuno H. C.; Matos, Jorge; Frizell, Kathleen H.

    2010-01-01

    The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously the magnitude and direction of the velocity vector in complex air-water flows, is described in this paper. The air-water flows envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton and Cross-Flow turbines), where the flow direction is not known prior to the data acquisition. The calibration of both the conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was placed in a position similar to that adopted for the flow measurements, will be reported. After concluding the calibration procedure, the probe was utilized in the outside region of a Cross-Flow turbine rotor. The experimental results obtained in the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing the velocity field of other complex air-water flows.

  2. Design of passively aerated compost piles: Vertical air velocities between the pipes

    SciTech Connect

    Lynch, N.J.; Cherry, R.S.

    1996-09-01

    Passively aerated compost piles are built on a base of porous materials, such as straw or wood chips, in which perforated air supply pipes are distributed. The piles are not turned during composting, nor is forced-aeration equipment used, which significantly reduces the operating and capital expenses associated with these piles. Currently, pile configurations and materials are worked out by trial and error. Fundamentally based design procedures are difficult to develop because the natural convection air flow rate is not explicitly known, but rather is closely coupled with the pile temperature. This paper develops a mathematical model to analytically determine the maximum upward air flow velocity over an air supply pipe and the drop in vertical velocity away from the pipe. This model has one dimensionless number, dependent on the pile and base properties, which fully characterizes the velocity profile between the pipes. 9 refs., 4 figs., 1 tab.

  3. Simulation development and evaluation of an improved longitudinal velocity vector control wheel steering mode and electronic display format

    NASA Technical Reports Server (NTRS)

    Steinmetz, G. G.

    1980-01-01

    Using simulation, an improved longitudinal velocity vector control wheel steering mode and an improved electronic display format for an advanced flight system were developed and tested. Guidelines for the development phase were provided by test pilot critique summaries of the previous system. The results include performances from computer generated step column inputs across the full airplane speed and configuration envelope, as well as piloted performance results taken from a reference line tracking task and an approach to landing task conducted under various environmental conditions. The analysis of the results for the reference line tracking and approach to landing tasks indicates clearly detectable improvement in pilot tracking accuracy with a reduction in physical workload. The original objectives of upgrading the longitudinal axis of the velocity vector control wheel steering mode were successfully met when measured against the test pilot critique summaries and the original purpose outlined for this type of augment control mode.

  4. Inert gas influence on the laminar burning velocity of methane-air mixtures.

    PubMed

    Mitu, Maria; Giurcan, Venera; Razus, Domnina; Oancea, Dumitru

    2017-01-05

    Flame propagation was studied in methane-air-inert (He, Ar, N2 or CO2) mixtures with various initial pressures and compositions using pressure-time records obtained in a spherical vessel with central ignition. The laminar burning velocities of CH4-air and CH4-air-inert mixtures obtained from experimental p(t) records of the early stage of combustion were compared with literature data and with those obtained from numerical modeling of 1D flames. The overall reaction orders of methane oxidation were determined from the baric coefficients of the laminar burning velocities determined from power-law equations. For all mixtures, the adiabatic flames temperatures were computed, assuming that the chemical equilibrium is reached in the flame front. The overall activation energy for the propagation stage of the combustion process was determined from the temperature dependence of the laminar burning velocity.

  5. Influence of air velocity on the habit of ice crystal growth from the vapor

    NASA Technical Reports Server (NTRS)

    Keller, V. W.; Hallett, J.

    1982-01-01

    The effect of air velocity on the growth behavior of ice crystals growing from water vapor was investigated at temperatures between 0 and -35 C and at supersaturation levels ranging from 2 to 40 percent, using a laboratory chamber in which it was possible to make these variations. It was found that crystal growth was most sensitive to changes in the air velocity at temperatures near -4 C and -15 C where, near water saturation, the introduction of only a 5 cm/s air velocity induced skeletal transitions (columns to needles near -4 C and plates to dendrites near -15 C). The experiments provide conditions which simulate growth of ice crystals in the atmosphere, where crystal growth takes place at or somewhat below water saturation.

  6. Generalizing the wavelet-based multifractal formalism to random vector fields: application to three-dimensional turbulence velocity and vorticity data.

    PubMed

    Kestener, Pierre; Arneodo, Alain

    2004-07-23

    We use singular value decomposition techniques to generalize the wavelet transform modulus maxima method to the multifractal analysis of vector-valued random fields. The method is calibrated on synthetic multifractal 2D vector measures and monofractal 3D fractional Brownian vector fields. We report the results of some application to the velocity and vorticity fields issued from 3D isotropic turbulence simulations. This study reveals the existence of an intimate relationship between the singularity spectra of these two vector fields which are found significantly more intermittent than previously estimated from longitudinal and transverse velocity increment statistics.

  7. Measurement of temperature and velocity fields in a convective fluid flow in air using schlieren images.

    PubMed

    Martínez-González, A; Moreno-Hernández, D; Guerrero-Viramontes, J A

    2013-08-01

    A convective fluid flow in air could be regulated if the physical process were better understood. Temperature and velocity measurements are required in order to obtain a proper characterization of a convective fluid flow. In this study, we show that a classical schlieren system can be used for simultaneous measurements of temperature and velocity in a convective fluid flow in air. The schlieren technique allows measurement of the average fluid temperature and velocity integrated in the direction of the test beam. Therefore, in our experiments we considered surfaces with isothermal conditions. Temperature measurements are made by relating the intensity level of each pixel in a schlieren image to the corresponding knife-edge position measured at the exit focal plane of the schlieren system. The same schlieren images were also used to measure the velocity of the fluid flow by using optical flow techniques. The algorithm implemented analyzes motion between consecutive schlieren frames to obtain a tracked sequence and finally velocity fields. The proposed technique was applied to measure the temperature and velocity fields in natural convection of air due to unconfined and confined heated rectangular plates.

  8. Laminar Flame Velocity and Temperature Exponent of Diluted DME-Air Mixture

    NASA Astrophysics Data System (ADS)

    Naseer Mohammed, Abdul; Anwar, Muzammil; Juhany, Khalid A.; Mohammad, Akram

    2017-03-01

    In this paper, the laminar flame velocity and temperature exponent diluted dimethyl ether (DME) air mixtures are reported. Laminar premixed mixture of DME-air with volumetric dilutions of carbon dioxides (CO2) and nitrogen (N2) are considered. Experiments were conducted using a preheated mesoscale high aspect-ratio diverging channel with inlet dimensions of 25 mm × 2 mm. In this method, flame velocities are extracted from planar flames that were stabilized near adiabatic conditions inside the channel. The flame velocities are then plotted against the ratio of mixture temperature and the initial reference temperature. A non-linear power law regression is observed suitable. This regression analysis gives the laminar flame velocity at the initial reference temperature and temperature exponent. Decrease in the laminar flame velocity and increase in temperature exponent is observed for CO2 and N2 diluted mixtures. The addition of CO2 has profound influence when compared to N2 addition on both flame velocity and temperature exponent. Numerical prediction of the similar mixture using a detailed reaction mechanism is obtained. The computational mechanism predicts higher magnitudes for laminar flame velocity and smaller magnitudes of temperature exponent compared to experimental data.

  9. Force, velocity, and work: The effects of different contexts on students' understanding of vector concepts using isomorphic problems

    NASA Astrophysics Data System (ADS)

    Barniol, Pablo; Zavala, Genaro

    2014-12-01

    In this article we compare students' understanding of vector concepts in problems with no physical context, and with three mechanics contexts: force, velocity, and work. Based on our "Test of Understanding of Vectors," a multiple-choice test presented elsewhere, we designed two isomorphic shorter versions of 12 items each: a test with no physical context, and a test with mechanics contexts. For this study, we administered the items twice to students who were finishing an introductory mechanics course at a large private university in Mexico. The first time, we administered the two 12-item tests to 608 students. In the second, we only tested the items for which we had found differences in students' performances that were difficult to explain, and in this case, we asked them to show their reasoning in written form. In the first administration, we detected no significant difference between the medians obtained in the tests; however, we did identify significant differences in some of the items. For each item we analyze the type of difference found between the tests in the selection of the correct answer, the most common error on each of the tests, and the differences in the selection of incorrect answers. We also investigate the causes of the different context effects. Based on these analyses, we establish specific recommendations for the instruction of vector concepts in an introductory mechanics course. In the Supplemental Material we include both tests for other researchers studying vector learning, and for physics teachers who teach this material.

  10. Fiber-Based Doppler Lidar for Vector Velocity and Altitude Measurements

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Pierrottet, Diego; Hines, Glenn; Petway, Larry; Barnes, Bruce

    2015-01-01

    A coherent Doppler lidar capable of providing accurate velocity and altitude data has been developed and demonstrated for future NASA missions to the solar system bodies requiring precision navigation and controlled soft landing.

  11. Measuring two-dimensional components of a flow velocity vector using a hot-wire probe.

    PubMed

    Kiełbasa, Jan

    2007-08-01

    The article presents a single-hot-wire probe adapted to detect the direction of flow velocity. The modification consists of the introduction of a third support which allows to measure voltage at the central point of the wire. The sign of voltage difference DeltaU between both parts of the wire is the measure of the direction of flow velocity in a system of coordinates associated with the probe.

  12. Preservation of Cognitive Performance with Age during Exertional Heat Stress under Low and High Air Velocity

    PubMed Central

    Wright Beatty, Heather E.; Keillor, Jocelyn M.; Hardcastle, Stephen G.; Boulay, Pierre; Kenny, Glen P.

    2015-01-01

    Older adults may be at greater risk for occupational injuries given their reduced capacity to dissipate heat, leading to greater thermal strain and potentially cognitive decrements. Purpose. To examine the effects of age and increased air velocity, during exercise in humid heat, on information processing and attention. Methods. Nine young (24 ± 1 years) and 9 older (59 ± 1 years) males cycled 4 × 15 min (separated by 15 min rest) at a fixed rate of heat production (400 W) in humid heat (35°C, 60% relative humidity) under 0.5 (low) and 3.0 (high) m·s−1 air velocity wearing coveralls. At rest, immediately following exercise (end exercise), and after the final recovery, participants performed an abbreviated paced auditory serial addition task (PASAT, 2 sec pace). Results. PASAT numbers of correct responses at end exercise were similar for young (low = 49 ± 3; high = 51 ± 3) and older (low = 46 ± 5; high = 47 ± 4) males and across air velocity conditions, and when scored relative to age norms. Psychological sweating, or an increased sweat rate with the administration of the PASAT, was observed in both age groups in the high condition. Conclusion. No significant decrements in attention and speeded information processing were observed, with age or altered air velocity, following intermittent exercise in humid heat. PMID:25874223

  13. Measurement of the Group Velocity Dispersion of air using a femtosecond comb

    NASA Astrophysics Data System (ADS)

    Al salamah, Reem

    In this thesis, the Group Velocity Dispersion (GVD) of air has been measured by using a femtosecond frequency comb at 1.5 microm. By comparing the spectra from a balanced and unbalanced Mach - Zehnder interferometer, the need for vacuum tube is eliminated. The method employs the Fast Fourier Transform of both auto- and cross correlation to find the spectral and their differences. The GVD of air is then calculated from these spectral phase differences. With twenty-five independent measurements, the GVD of air was found to be 0.0120 fs2/mm, with a standard deviation of 0.0075 fs2/mm.

  14. Research on inert gas narcosis and air velocity effects on metabolic performance

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The effects of air velocity on metabolic performance are studied by using high forced airflow in a closed environment as a mechanism to control the concentration of volatile animal wastes. Air velocities between 100 and 200 ft/min are without significant effects on the metabolism of rats. At velocities of 200 ft/min and above, oxygen consumption and CO2 production as well as food consumption increase. In most instances, the changes are on the order of 5-10%. At the same time, the RQ for the animals increases slightly and generally correlates well with oxygen consumption and CO2 production. Experiments on the nature of inert gas narcosis show that halothane and methoxyflurane are rather potent inhibitors of the NADH:O2 oxidoreductase system in rats. These experiments suggest that the mechanism of inert gas narcosis is not mandatorily related to a membrane surface phenomenon.

  15. A multi-channel, low velocity, hot film anemometry system for measuring air flows in buildings

    SciTech Connect

    Guire, J.L.

    1987-01-01

    A complete analytical and experimental development of a multichannel anemometry system is presented. The system consists of an array of low velocity sensors (0.0 m/s to 1.0 m/s), a constant current power supply, and the required data acquisition equipment. The velocity sensors can be scanned simultaneously yielding absolute air velocities and absolute ambient air temperatures at each of the probe positions in the array. One of the key results that this system can produce is the relationship between boundary layer flow and pressure driven flow through a large irregular aperture, such as a doorway, which up until now has been difficult to accomplish with regard to cost and experimental error incurred. 7 refs., 57 figs.

  16. THE M31 VELOCITY VECTOR. II. RADIAL ORBIT TOWARD THE MILKY WAY AND IMPLIED LOCAL GROUP MASS

    SciTech Connect

    Van der Marel, Roeland P.; Sohn, Sangmo Tony; Anderson, Jay; Brown, Tom; Fardal, Mark; Besla, Gurtina; Beaton, Rachael L.; Guhathakurta, Puragra

    2012-07-01

    We determine the velocity vector of M31 with respect to the Milky Way and use this to constrain the mass of the Local Group, based on Hubble Space Telescope proper-motion measurements of three fields presented in Paper I. We construct N-body models for M31 to correct the measurements for the contributions from stellar motions internal to M31. This yields an unbiased estimate for the M31 center-of-mass motion. We also estimate the center-of-mass motion independently, using the kinematics of satellite galaxies of M31 and the Local Group, following previous work but with an expanded satellite sample. All estimates are mutually consistent, and imply a weighted average M31 heliocentric transverse velocity of (v{sub W} , v{sub N} ) = (- 125.2 {+-} 30.8, -73.8 {+-} 28.4) km s{sup -1}. We correct for the reflex motion of the Sun using the most recent insights into the solar motion within the Milky Way, which imply a larger azimuthal velocity than previously believed. This implies a radial velocity of M31 with respect to the Milky Way of V{sub rad,M31} = -109.3 {+-} 4.4 km s{sup -1}, and a tangential velocity of V{sub tan,M31} = 17.0 km s{sup -1}, with a 1{sigma} confidence region of V{sub tan,M31} {<=} 34.3 km s{sup -1}. Hence, the velocity vector of M31 is statistically consistent with a radial (head-on collision) orbit toward the Milky Way. We revise prior estimates for the Local Group timing mass, including corrections for cosmic bias and scatter, and obtain M{sub LG} {identical_to} M{sub MW,vir} + M{sub M31,vir} = (4.93 {+-} 1.63) Multiplication-Sign 10{sup 12} M{sub Sun }. Summing known estimates for the individual masses of M31 and the Milky Way obtained from other dynamical methods yields smaller uncertainties. Bayesian combination of the different estimates demonstrates that the timing argument has too much (cosmic) scatter to help much in reducing uncertainties on the Local Group mass, but its inclusion does tend to increase other estimates by {approx}10%. We

  17. Estimation of velocity vector angles using the directional cross-correlation method.

    PubMed

    Kortbek, Jacob; Jensen, Jørgen Arendt

    2006-11-01

    A method for determining both velocity magnitude and angle in any direction is suggested. The method uses focusing along the velocity direction and cross-correlation for finding the correct velocity magnitude. The angle is found from beamforming directional signals in a number of directions and then selecting the angle with the highest normalized correlation between directional signals. The approach is investigated using Field II simulations and data from the experimental ultrasound scanner RASMUS and a circulating flow rig with a parabolic flow having a peak velocity of 0.3 m/s. A 7-MHz linear array transducer is used with a normal transmission of a focused ultrasound field. In the simulations the relative standard deviation of the velocity magnitude is between 0.7% and 7.7% for flow angles between 45 degrees and 90 degrees. The study showed that angle estimation by directional beamforming can be estimated with a high precision. The angle estimation performance is highly dependent on the choice of the time ktprf x Tprf (correlation time) between signals to correlate. One performance example is given with a fixed value of ktprf for all flow angles. The angle estimation on measured data for flow at 60 degrees to 90 degrees yields a probability of valid estimates between 68% and 98%. The optimal value of ktprf for each flow angle is found from a parameter study; with these values, the performance on simulated data yields angle estimates with no outlier estimates and with standard deviations below 2 degrees.

  18. Sensory and chemical characterization of VOC emissions from building products: impact of concentration and air velocity

    NASA Astrophysics Data System (ADS)

    Knudsen, H. N.; Kjaer, U. D.; Nielsen, P. A.; Wolkoff, P.

    The emissions from five commonly used building products were studied in small-scale test chambers over a period of 50 days. The odor intensity was assessed by a sensory panel and the concentrations of selected volatile organic compounds (VOCs) of concern for the indoor air quality were measured. The building products were three floor coverings: PVC, floor varnish on beechwood parquet and nylon carpet on a latex foam backing; an acrylic sealant, and a waterborne wall paint on gypsum board. The impacts of the VOC concentration in the air and the air velocity over the building products on the odor intensity and on the emission rate of VOCs were studied. The emission from each building product was studied under two or three different area-specific ventilation rates, i.e. different ratios of ventilation rate of the test chamber and building product area in the test chamber. The air velocity over the building product samples was adjusted to different levels between 0.1 and 0.3 m s -1. The origin of the emitted VOCs was assessed in order to distinguish between primary and secondary emissions. The results show that it is reasonable after an initial period of up to 14 days to consider the emission rate of VOCs of primary origin from most building products as being independent of the concentration and of the air velocity. However, if the building product surface is sensitive to oxidative degradation, increased air velocity may result in increased secondary emissions. The odor intensity of the emissions from the building products only decayed modestly over time. Consequently, it is recommended to use building products which have a low impact on the perceived air quality from the moment they are applied. The odor indices (i.e. concentration divided by odor threshold) of primary VOCs decayed markedly faster than the corresponding odor intensities. This indicates that the secondary emissions rather than the primary emissions, are likely to affect the perceived air quality in the

  19. ADL ORVIS: An air-delay-leg, line-imaging optically recording velocity interferometer system

    NASA Astrophysics Data System (ADS)

    Trott, Wayne M.; Castañeda, Jaime N.; Cooper, Marcia A.

    2014-04-01

    An interferometry system that enables acquisition of spatially resolved velocity-time profiles with very high velocity sensitivity has been designed and applied to two diverse, instructive experimental problems: (1) measurement of low-amplitude reverberations in laser-driven flyer plates and (2) measurement of ramp-wave profiles in symmetric impact studies of fused silica. The delay leg in this version of a line-imaging optically recording velocity interferometer system (ORVIS) consists of a long air path that includes relay optics to transmit the optical signal through the interferometer cavity. Target image quality from the delay path at the image recombination plane is preserved by means of a compact and flexible optical design utilizing two parabolic reflectors (serving as the relay optics) in a folded path. With an instrument tuned to a velocity per fringe constant of 22.4 m s-1 fringe-1, differences of 1-2 m s-1 across the probe line segment can be readily distinguished. Measurements that capture small spatial variations in flyer velocity are presented and briefly discussed. In the fused silica impact experiments, the ramp-wave profile observed by this air-delay instrument compares favorably to the profile recorded simultaneously by a conventional line-imaging ORVIS.

  20. Laminar burning velocities and flame instabilities of butanol isomers-air mixtures

    SciTech Connect

    Gu, Xiaolei; Huang, Zuohua; Wu, Si; Li, Qianqian

    2010-12-15

    Laminar burning velocities and flame instabilities of the butanol-air premixed flames and its isomers are investigated using the spherically expanding flame with central ignition at initial temperature of 428 K and initial pressures of 0.10 MPa, 0.25 MPa, 0.50 MPa and 0.75 MPa. Laminar burning velocities and sensitivity factor of n-butanol-air mixtures are computed using a newly developed kinetic mechanism. Unstretched laminar burning velocity, adiabatic temperature, Lewis number, Markstein length, critical flame radius and Peclet number are obtained over a wide range of equivalence ratios. Effect of molecular structure on laminar burning velocity of the isomers of butanol is analyzed from the aspect of C-H bond dissociation energy. Study indicates that although adiabatic flame temperatures of the isomers of butanol are the same, laminar burning velocities give an obvious difference among the isomers of butanol. This indicates that molecular structure has a large influence on laminar burning velocities of the isomers of butanol. Branching (-CH3) will decrease laminar burning velocity. Hydroxyl functional group (-OH) attaching to the terminal carbon atoms gives higher laminar burning velocity compared to that attaching to the inner carbon atoms. Calculated dissociation bond energies show that terminal C-H bonds have larger bond energies than that of inner C-H bonds. n-Butanol, no branching and with hydroxyl functional group (-OH) attaching to the terminal carbon atom, gives the largest laminar burning velocity. tert-Butanol, with highly branching and hydroxyl functional group (-OH) attaching to the inner carbon atom, gives the lowest laminar burning velocity. Laminar burning velocities of iso-butanol and sec-butanol are between those of n-butanol and tert-butanol. The instant of transition to cellularity is experimentally determined for the isomers of butanol and subsequently interpreted on the basis of hydrodynamic and diffusion-thermal instabilities. Little effect

  1. Live performance of male broilers subjected to constant or increasing air velocities at moderate temperatures with a high dew point.

    PubMed

    Dozier, W A; Lott, B D; Branton, S L

    2005-08-01

    This study examined the effects of varying air velocities vs. a constant air velocity with a cyclic temperature curve of 25-30-25 degrees C and a dew point of 23 degrees C on broilers from 28 to 49 d of age. Four replicate trials were conducted. In each trial, 742 male broilers were randomly allocated to 6 floor pens or 2 air velocity tunnels, with each tunnel consisting of 4 pens. Bird density, feeder, and waterer space were similar across all pens (53 birds/ pen; 0.07 m2/bird). The treatments were control (still air), constant air velocity of 120 m/min, and increasing air velocity (90 m/min from 28 to 35 d, 120 m/min from 36 to 42 d, and 180 m/min from 43 to 49 d). Birds grown in a still air environment gained less weight, consumed less feed, and converted feed less efficiently between 28 and 49 d than birds subjected to moving air (constant or increasing). Growth responses between the air velocity treatments were similar from 28 to 35 and 36 to 42 d of age. Increasing air velocity to 180 m/min improved (P < or = 0.02) the growth rate of broilers from 43 to 49 d of age over birds receiving an air velocity of 120 m/min, but the incidence of mortality was not affected. These results provide evidence that increasing air velocity from 120 to 180 m/min is beneficial to broilers weighing 2.5 kg or greater when exposed to moderate temperatures.

  2. Optimization and investigation of the effect of velocity distribution of air curtains on the performance of food refrigerated display cabinets

    NASA Astrophysics Data System (ADS)

    Wu, XueHong; Chang, ZhiJuan; Ma, QiuYang; Lu, YanLi; Yin, XueMei

    2016-08-01

    This paper focuses on improving the performance of the vertical open refrigerated display cabinets (VORDC) by optimizing the structure of deflector, which is affected by inlet velocity and velocity distribution of air curtains. The results show that the temperature of products located at the front and at the rear reduces as the increases of inlet velocity of air curtains. The increase of the inlet velocity of air curtains can strengthen the disturbance inside the VORDC, and also decrease the temperature of products inside the VORDC; the increase of the outer velocity of air curtain will exacerbate the disturbance outside the VORDC and decrease air curtain's performance. The present study can provide a theoretical foundation for the design of VORDC.

  3. A Hypothetical Burning-Velocity Formula for Very Lean Hydrogen-Air Mixtures

    SciTech Connect

    Williams, Forman; Williams, Forman A; Grcar, Joseph F

    2008-06-30

    Very lean hydrogen-air mixtures experience strong diffusive-thermal types of cellular instabilities that tend to increase the laminar burning velocity above the value that applies to steady, planar laminar flames that are homogeneous in transverse directions. Flame balls constitute an extreme limit of evolution of cellular flames. To account qualitatively for the ultimate effect of diffusive-thermal instability, a model is proposed in which the flame is a steadily propagating, planar, hexagonal, close-packed array of flame balls, each burning as if it were an isolated, stationary, ideal flame ball in an infinite, quiescent atmosphere. An expression for the laminar burning velocity is derived from this model, which theoretically may provide an upper limit for the experimental burning velocity.

  4. Measurements of Flat-Flame Velocities of Diethyl Ether in Air

    PubMed Central

    Gillespie, Fiona; Metcalfe, Wayne K.; Dirrenberger, Patricia; Herbinet, Olivier; Glaude, Pierre-Alexandre; Battin-Leclerc, Frédérique; Curran, Henry J.

    2013-01-01

    This study presents new adiabatic laminar burning velocities of diethyl ether in air, measured on a flat-flame burner using the heat flux method. The experimental pressure was 1 atm and temperatures of the fresh gas mixture ranged from 298 to 398 K. Flame velocities were recorded at equivalence ratios from 0.55 to 1.60, for which stabilization of the flame was possible. The maximum laminar burning velocity was found at an equivalence ratio of 1.10 or 1.15 at different temperatures. These results are compared with experimental and computational data reported in the literature. The data reported in this study deviate significantly from previous experimental results and are well-predicted by a previously reported chemical kinetic mechanism. PMID:23710107

  5. Particle velocity gradient based acoustic mode beamforming for short linear vector sensor arrays.

    PubMed

    Gur, Berke

    2014-06-01

    In this paper, a subtractive beamforming algorithm for short linear arrays of two-dimensional particle velocity sensors is described. The proposed method extracts the highly directional acoustic modes from the spatial gradients of the particle velocity field measured at closely spaced sensors along the array. The number of sensors in the array limits the highest order of modes that can be extracted. Theoretical analysis and numerical simulations indicate that the acoustic mode beamformer achieves directivity comparable to the maximum directivity that can be obtained with differential microphone arrays of equivalent aperture. When compared to conventional delay-and-sum beamformers for pressure sensor arrays, the proposed method achieves comparable directivity with 70%-85% shorter apertures. Moreover, the proposed method has additional capabilities such as high front-back (port-starboard) discrimination, frequency and steer direction independent response, and robustness to correlated ambient noise. Small inter-sensor spacing that results in very compact apertures makes the proposed beamformer suitable for space constrained applications such as hearing aids and short towed arrays for autonomous underwater platforms.

  6. Measurements of laminar burning velocities for natural gas-hydrogen-air mixtures

    SciTech Connect

    Huang, Zuohua; Zhang, Yong; Zeng, Ke; Liu, Bing; Wang, Qian; Jiang, Deming

    2006-07-15

    Laminar flame characteristics of natural gas-hydrogen-air flames were studied in a constant-volume bomb at normal temperature and pressure. Laminar burning velocities and Markstein lengths were obtained at various ratios of hydrogen to natural gas (volume fraction from 0 to 100%) and equivalence ratios (f from 0.6 to 1.4). The influence of stretch rate on flame was also analyzed. The results show that, for lean mixture combustion, the flame radius increases with time but the increasing rate decreases with flame expansion for natural gas and for mixtures with low hydrogen fractions, while at high hydrogen fractions, there exists a linear correlation between flame radius and time. For rich mixture combustion, the flame radius shows a slowly increasing rate at early stages of flame propagation and a quickly increasing rate at late stages of flame propagation for natural gas and for mixtures with low hydrogen fractions, and there also exists a linear correlation between flame radius and time for mixtures with high hydrogen fractions. Combustion at stoichiometric mixture demonstrates the linear relationship between flame radius and time for natural gas-air, hydrogen-air, and natural gas-hydrogen-air flames. Laminar burning velocities increase exponentially with the increase of hydrogen fraction in mixtures, while the Markstein length decreases and flame instability increases with the increase of hydrogen fractions in mixture. For a fixed hydrogen fraction, the Markstein number shows an increase and flame stability increases with the increase of equivalence ratios. Based on the experimental data, a formula for calculating the laminar burning velocities of natural gas-hydrogen-air flames is proposed. (author)

  7. Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocity.

    PubMed

    Bugbee, B; Monje, O; Tanner, B

    1996-01-01

    Here we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature.

  8. Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocity

    NASA Technical Reports Server (NTRS)

    Bugbee, B.; Monje, O.; Tanner, B.

    1996-01-01

    Here we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature.

  9. Tuning a physically-based model of the air-sea gas transfer velocity

    NASA Astrophysics Data System (ADS)

    Jeffery, C. D.; Robinson, I. S.; Woolf, D. K.

    Air-sea gas transfer velocities are estimated for one year using a 1-D upper-ocean model (GOTM) and a modified version of the NOAA-COARE transfer velocity parameterization. Tuning parameters are evaluated with the aim of bringing the physically based NOAA-COARE parameterization in line with current estimates, based on simple wind-speed dependent models derived from bomb-radiocarbon inventories and deliberate tracer release experiments. We suggest that A = 1.3 and B = 1.0, for the sub-layer scaling parameter and the bubble mediated exchange, respectively, are consistent with the global average CO 2 transfer velocity k. Using these parameters and a simple 2nd order polynomial approximation, with respect to wind speed, we estimate a global annual average k for CO 2 of 16.4 ± 5.6 cm h -1 when using global mean winds of 6.89 m s -1 from the NCEP/NCAR Reanalysis 1 1954-2000. The tuned model can be used to predict the transfer velocity of any gas, with appropriate treatment of the dependence on molecular properties including the strong solubility dependence of bubble-mediated transfer. For example, an initial estimate of the global average transfer velocity of DMS (a relatively soluble gas) is only 11.9 cm h -1 whilst for less soluble methane the estimate is 18.0 cm h -1.

  10. Inferring plasma flow velocities from photospheric vector magnetic field observations for the investigation of flare onsets

    NASA Astrophysics Data System (ADS)

    Santos, J. C.; Büchner, J.; Zhang, H.

    2008-09-01

    The amount of emergence and submergence of magnetized plasma and the horizontal motion of the footpoints of flux tubes might be crucial for the dynamics of the solar atmosphere. Although the rate of flux emergence and submergence can be observationally determined near the polarity inversion line (Chae et al., 2004), the same is not true for regions away from the PIL. Also, the horizontal motions cannot be directly measured in the solar photosphere. In this sense, the evolution of the photospheric magnetic field provides valuable information which can be used to estimate photospheric plasma flows since magnetic field and plasma are closely associated (frozen-in-condition). We used three methods to estimate the photospheric plasma motion from magnetic field observations. The methods were applied to photospheric vector magnetic field data of active region NOAA 9077, observed by the Huairou Solar Observing Station (HSOS) of the National Astronomical Observatories of China before and after the ‘Bastille Day’ flare on July 13th and 14th, 2000.

  11. A support vector regression-firefly algorithm-based model for limiting velocity prediction in sewer pipes.

    PubMed

    Ebtehaj, Isa; Bonakdari, Hossein

    2016-01-01

    Sediment transport without deposition is an essential consideration in the optimum design of sewer pipes. In this study, a novel method based on a combination of support vector regression (SVR) and the firefly algorithm (FFA) is proposed to predict the minimum velocity required to avoid sediment settling in pipe channels, which is expressed as the densimetric Froude number (Fr). The efficiency of support vector machine (SVM) models depends on the suitable selection of SVM parameters. In this particular study, FFA is used by determining these SVM parameters. The actual effective parameters on Fr calculation are generally identified by employing dimensional analysis. The different dimensionless variables along with the models are introduced. The best performance is attributed to the model that employs the sediment volumetric concentration (C(V)), ratio of relative median diameter of particles to hydraulic radius (d/R), dimensionless particle number (D(gr)) and overall sediment friction factor (λ(s)) parameters to estimate Fr. The performance of the SVR-FFA model is compared with genetic programming, artificial neural network and existing regression-based equations. The results indicate the superior performance of SVR-FFA (mean absolute percentage error = 2.123%; root mean square error =0.116) compared with other methods.

  12. Effects of light intensity light quality and air velocity on temperature in plant reproductive organs

    NASA Astrophysics Data System (ADS)

    Kitaya, Y.; Hirai, H.

    Excess temperature increase in plant reproductive organs such as anthers and stigmata could cause fertility impediments and thus produce sterile seeds under artificial lighting conditions in closed plant growth facilities There is a possibility that the aberration was caused by an excess increase in temperatures of reproductive organs in Bioregenerative Life Support Systems under microgravity conditions in space The fundamental study was conducted to know the thermal situation of the plant reproductive organs as affected by light intensity light quality and air velocity on the earth and to estimate the excess temperature increase in the reproductive organs in closed plant growth facilities in space Thermal images of reproductive organs of rice and strawberry were captured using infrared thermography at an air temperature of 10 r C The temperatures in flowers at 300 mu mol m -2 s -1 PPFD under the lights from red LEDs white LEDs blue LEDs fluorescent lamps and incandescent lamps increased by 1 4 1 7 1 9 6 0 and 25 3 r C respectively for rice and by 2 8 3 4 4 1 7 8 and 43 4 r C respectively for strawberry The flower temperatures increased with increasing PPFD levels The temperatures in petals anthers and stigmas of strawberry at 300 mu mol m -2 s -1 PPFD under incandescent lamps increased by 32 7 29 0 and 26 6 r C respectively at 0 1 m s -1 air velocity and by 20 6 18 5 and 15 9 r C respectively at 0 8 m s -1 air velocity The temperatures of reproductive organs decreased with increasing

  13. DIRDOP: a directivity approach to determining the seismic rupture velocity vector

    NASA Astrophysics Data System (ADS)

    Caldeira, Bento; Bezzeghoud, Mourad; Borges, José F.

    2010-07-01

    Directivity effects are a characteristic of seismic source finiteness and are a consequence of the rupture spread in preferential directions. These effects are manifested through seismic spectral deviations as a function of the observation location. The directivity by Doppler effect method permits estimation of the directions and rupture velocities, beginning from the duration of common pulses, which are identified in waveforms or relative source time functions. The general model of directivity that supports the method presented here is a Doppler analysis based on a kinematic source model of rupture (Haskell, Bull Seismol Soc Am 54:1811-1841, 1964) and a structural medium with spherical symmetry. To evaluate its performance, we subjected the method to a series of tests with synthetic data obtained from ten typical seismic ruptures. The experimental conditions studied correspond with scenarios of simple and complex, unilaterally and bilaterally extended ruptures with different mechanisms and datasets with different levels of azimuthal coverage. The obtained results generally agree with the expected values. We also present four real case studies, applying the method to the following earthquakes: Arequipa, Peru ( M w = 8.4, June 23, 2001); Denali, AK, USA ( M w = 7.8; November 3, 2002); Zemmouri-Boumerdes, Algeria ( M w = 6.8, May 21, 2003); and Sumatra, Indonesia ( M w = 9.3, December 26, 2004). The results obtained from the dataset of the four earthquakes agreed, in general, with the values presented by other authors using different methods and data.

  14. Correlation between myocardial dysfunction and perfusion impairment in diabetic rats with velocity vector imaging and myocardial contrast echocardiography.

    PubMed

    Wei, Zhangrui; Zhang, Haibin; Su, Haili; Zhu, Ting; Zhu, Yongsheng; Zhang, Jun

    2012-11-01

    The purpose of this study was to investigate whether myocardial systolic dysfunction and perfusion impairment occur in diabetic rats, and to assess their relationship using velocity vector imaging (VVI) and myocardial contrast echocardiography (MCE). Forty-six rats were randomly divided into either control or the diabetes mellitus (DM) groups. DM was induced by intraperitoneal administration of streptozotocin. Twelve weeks later, 39 survival rats underwent VVI and MCE in short-axis view at the middle level of the left ventricle, both at rest and after dipyridamole stress. VVI-derived contractile parameters included peak systolic velocity (Vs ), circumferential strain (εc ), strain rate (SRc ), and their reserves. MCE-derived perfusion parameters consisted of myocardial blood flow (MBF) and myocardial flow reserve (MFR). At rest, SRc in the DM group was significantly lower than in the control group, Vs , εc , and MBF did not differ significantly between groups. After dipyridamole stress, all VVI parameters and their reserves in the DM group were significantly lower than those in the control group, MBF and MFR were substantially lower than those in the control group, too. Meanwhile, significant correlations between VVI parameter reserves and MFR were observed in the DM group. Both myocardial systolic function and perfusion were impaired in DM rats. Decreased MFR could be an important contributor to the reduction in myocardial contractile reserve.

  15. The effect of humidity on ionic wind velocity in ambient air

    NASA Astrophysics Data System (ADS)

    Chen, She; Nobelen, J. C. P. Y.; Nijdam, S.

    2016-09-01

    Due to the evolution of portable electronics and LED lightning system, advances in air cooling technologies must also keep pace. Active cooling by ionic wind, which is usually generated by corona discharge, can greatly reduce the noise and lifetime issues compared to the mechanical fans. The wind is induced when a gas discharge is formed, and neutral molecules gain their energy by the momentum transfer of ion-neutral collisions. However, there is few discussion about the effect of gas composition such as humidity on the wind generation and the physical mechanism is not clear. In the experiment, a positive 5-20 kV DC voltage is applied to the needle-cylinder electrodes with separation of 20 mm. The ionic wind velocity is measured by hot wire anemometry. As the relative humidity (RH) in the ambient air increases, the velocity is found to be severely inhibited. The current is also measured between the cylinder electrode and earth. The results show that the DC component of corona current decreases when RH increases. Since both the discharge current and the ion mobility are reduced when RH increases, their combined effects determine the ionic wind velocity. This work is supported by STW project 13651.

  16. An Idea of Staged and Large Velocity Differential Secondary Air for Waterwall Erosion Protection and Oxygen Complementarity

    NASA Astrophysics Data System (ADS)

    Liu, B. Q.; Zhang, X. H.

    A successful design of circulating fluidized bed (CFB) boiler should have the highest combustion efficiency, economic operation, and optimum availability. There is a coupled phenomenon of an oxygen lean zone existing in the CFB boiler furnace which depresses combustion efficiency and particle (group) falling down faster and faster when it falls along the waterwall, abrading the tube metal effectively. A new secondary air design for the oxygen lean zone and erosion protection is conceived by using staged and large velocity differential secondary air. For example, a part of concentrate supplied secondary air has been divided into two parts: a low velocity part and a high velocity part. The low velocity part is used for rigid gas layer to reduce the particle falling velocity, and the high velocity part is used for oxygen supply. It is believed that 40˜6Om/s projecting air velocity could send new oxygen to at least half furnace depth in a short projecting lift as shown in calculation. In another view point, operational superficial gas velocity has an obvious effect on waterwall metal erosion, with a lower operation velocity having lower erosion.

  17. Burning Velocity Measurements in Aluminum-Air Suspensions using Bunsen Type Dust Flames

    NASA Technical Reports Server (NTRS)

    Lee, John; Goroshin, Samuel; Kolbe, Massimiliano

    2001-01-01

    Laminar burning velocity (sometimes also referred in literature as fundamental or normal flame propagation speed) is probably the most important combustion characteristic of the premixed combustible mixture. The majority of experimental data on burning velocities in gaseous mixtures was obtained with the help of the Bunsen conical flame. The Bunsen cone method was found to be sufficiently accurate for gaseous mixtures with burning velocities higher than 10-15 cm/s at normal pressure. Hans Cassel was the first to demonstrate that suspensions of micron-size solid fuel particles in a gaseous oxidizer can also form self-sustained Bunsen flames. He was able to stabilize Bunsen flames in a number of suspensions of different nonvolatile solid fuels (aluminum, carbon, and boron). Using the Bunsen cone method he estimated burning velocities in the premixed aluminum-air mixtures (particle size less than 10 microns) to be in the range of 30-40 cm/s. Cassel also found, that the burning velocity in dust clouds is a function of the burner diameter. In our recent work, we have used the Bunsen cone method to investigate dependence of burning velocity on dust concentration in fuel-rich aluminum dust clouds. Burning velocities in stoichiometric and fuel-rich aluminum dust suspensions with average particle sizes of about 5 microns were found to be in the range of 20-25 cm/s and largely independent on dust concentration. These results raise the question to what degree burning velocities derived from Bunsen flame specifically and other dust flame configurations in general, are indeed fundamental characteristics of the mixture and to what degree are they apparatus dependent. Dust flames in comparison to gas combustion, are thicker, may be influenced by radiation heat transfer in the flame front, respond differently to heat losses, and are fundamentally influenced by the particular flow configuration due to the particles inertia. Since characteristic spatial scales of dust flames are

  18. Velocity and temperature field characteristics of water and air during natural convection heating in cans.

    PubMed

    Erdogdu, Ferruh; Tutar, Mustafa

    2011-01-01

    Presence of headspace during canning is required since an adequate amount allows forming vacuum during the process. Sealing technology may not totally eliminate all entrapped gases, and headspace might affect heat transfer. Not much attention has been given to solve this problem in computational studies, and cans, for example, were mostly assumed to be fully filled with product. Therefore, the objective of this study was to determine velocity and temperature evolution of water and air in cans during heating to evaluate the relevance of headspace in the transport mechanism. For this purpose, canned water samples with a certain headspace were used, and required governing continuity, energy, and momentum equations were solved using a finite volume approach coupled with a volume of fluid element model. Simulation results correlated well with experimental results validating faster heating effects of headspace rather than insulation effects as reported in the literature. The organized velocity motions along the air-water interface were also shown. Practical Application: Canning is a universal and economic method for processing of food products, and presence of adequate headspace is required to form vacuum during sealing of the cans. Since sealing technology may not totally eliminate the entrapped gases, mainly air, headspace might affect heating rates in cans. This study demonstrated the increased heating rates in the presence of headspace in contrast with some studies in the literature. By applying the effect of headspace, required processing time for thermally processed foods can be reduced leading to more rapid processes and lower energy consumptions.

  19. Velocity and phase distribution measurements in vertical air-water annular flows

    SciTech Connect

    Vassallo, P.

    1997-07-01

    Annular flow topology for three air-water conditions in a vertical duct is investigated through the use of a traversing double-sensor hot-film anemometry probe and differential pressure measurements. Near wall measurements of mean and fluctuating velocities, as well as local void fraction, are taken in the liquid film, with the highest turbulent fluctuations occurring for the flow condition with the largest pressure drop. A modified law-of-the-wall formulation for wall shear is presented which, using near wall values of mean velocity and kinetic energy, agrees reasonably well with the average stress obtained from direct pressure drop measurements. The linear profile using wall coordinates in the logarithmic layer is preserved in annular flow; however, the slope and intercept of the profile differ from the single-phase values for the annular flow condition which has a thicker, more turbulent, liquid film.

  20. A model for sound velocity in a two-phase air-water bubbly flow

    SciTech Connect

    Chung, N.M.; Lin, W.K.; Pei, B.S.; Hsu, Y.Y. )

    1992-07-01

    In this paper, wave propagation in a homogeneous, low void fraction, two-phase air-water bubbly flow is analyzed through the compressibility of a single bubble to derive a P({rho}) relation; the dispersion relation is then derived by a homogeneous model. The phase velocity and attenuation calculated from the model are compared with existing data and are in good agreement. The momentum transfer effect is considered through the virtual mass term and is significant at a higher void fraction. The interfacial heat transfer between phases is significant at low frequency, while bubble scattering effects are important at high frequency (near resonance). Bubble behavior at both low and high frequency is derived based on the isothermal and the adiabatic cases, respectively. The phase velocity occurs at the limiting condition in both cases. Furthermore, resonance is present in the model, and the resonant frequency is determined.

  1. Velocity Fields of Axisymmetric Hydrogen-Air Counterflow Diffusion Flames from LDV, PIV, and Numerical Computation

    NASA Technical Reports Server (NTRS)

    Pellett, Gerald L.; Wilson, Lloyd G.; Humphreys, William M., Jr.; Bartram, Scott M.; Gartrell, Luther R.; Isaac, K. M.

    1995-01-01

    Laminar fuel-air counterflow diffusion flames (CFDFs) were studied using axisymmetric convergent-nozzle and straight-tube opposed jet burners (OJBs). The subject diagnostics were used to probe a systematic set of H2/N2-air CFDFs over wide ranges of fuel input (22 to 100% Ha), and input axial strain rate (130 to 1700 Us) just upstream of the airside edge, for both plug-flow and parabolic input velocity profiles. Laser Doppler Velocimetry (LDV) was applied along the centerline of seeded air flows from a convergent nozzle OJB (7.2 mm i.d.), and Particle Imaging Velocimetry (PIV) was applied on the entire airside of both nozzle and tube OJBs (7 and 5 mm i.d.) to characterize global velocity structure. Data are compared to numerical results from a one-dimensional (1-D) CFDF code based on a stream function solution for a potential flow input boundary condition. Axial strain rate inputs at the airside edge of nozzle-OJB flows, using LDV and PIV, were consistent with 1-D impingement theory, and supported earlier diagnostic studies. The LDV results also characterized a heat-release hump. Radial strain rates in the flame substantially exceeded 1-D numerical predictions. Whereas the 1-D model closely predicted the max I min axial velocity ratio in the hot layer, it overpredicted its thickness. The results also support previously measured effects of plug-flow and parabolic input strain rates on CFDF extinction limits. Finally, the submillimeter-scale LDV and PIV diagnostics were tested under severe conditions, which reinforced their use with subcentimeter OJB tools to assess effects of aerodynamic strain, and fueVair composition, on laminar CFDF properties, including extinction.

  2. Impact of air velocity, temperature, humidity, and air on long-term voc emissions from building products

    NASA Astrophysics Data System (ADS)

    Wolkoff, Peder

    The emissions of two volatile organic compounds (VOCs) of concern from five building products (BPs) were measured in the field and laboratory emission cell (FLEC) up to 250 d. The BPs (VOCs selected on the basis of abundance and low human odor thresholds) were: nylon carpet with latex backing (2-ethylhexanol, 4-phenylcyclohexene), PVC flooring (2-ethylhexanol, phenol), floor varnish on pretreated beechwood parquet (butyl acetate, N-methylpyrrolidone), sealant (hexane, dimethyloctanols), and waterborne wall paint on gypsum board (1,2-propandiol, Texanol). Ten different climate conditions were tested: four different air velocities from ca. 1 cm s -1 to ca. 9 cm s -1, three different temperatures (23, 35, and 60°C), two different relative humidities (0% and 50% RH), and pure nitrogen instead of clean air supply. Additionally, two sample specimen and two different batches were compared for repeatability and homogeneity. The VOCs were sampled on Tenax TA and determined by thermal desorption and gas chromatography (FID). Quantification was carried out by individual calibration of each VOC of concern. Concentration/time profiles of the selected VOCs (i.e. their concentration decay curves over time) in a standard room were used for comparison. Primary source emissions were not affected by the air velocity after a few days to any great extent. Both the temperature and relative humidity affected the emission rates, but depended strongly on the type of BP and type of VOC. Secondary (oxidative) source emissions were only observed for the PVC and for dimethyloctanols from the sealant. The time to reach a given concentration (emission rate) appears to be a good approach for future interlaboratory comparisons of BP's VOC emissions.

  3. Effect of low air velocities on thermal homeostasis and comfort during exercise at space station operational temperature and humidity

    NASA Technical Reports Server (NTRS)

    Beumer, Ronald J.

    1989-01-01

    The effectiveness of different low air velocities in maintaining thermal comfort and homeostasis during exercise at space station operational temperature and humidity was investigated. Five male subjects exercised on a treadmill for successive ten minute periods at 60, 71, and 83 percent of maximum oxygen consumption at each of four air velocities, 30, 50, 80, and 120 ft/min, at 22 C and 62 percent relative humidity. No consistent trends or statistically significant differences between air velocities were found in body weight loss, sweat accumulation, or changes in rectal, skin, and body temperatures. Occurrence of the smallest body weight loss at 120 ft/min, the largest sweat accumulation at 30 ft/min, and the smallest rise in rectal temperature and the greatest drop in skin temperature at 120 ft/min all suggested more efficient evaporative cooling at the highest velocity. Heat storage at all velocities was evidenced by increased rectal and body temperatures; skin temperatures declined or increased only slightly. Body and rectal temperature increases corresponded with increased perception of warmth and slight thermal discomfort as exercise progressed. At all air velocities, mean thermal perception never exceeded warm and mean discomfort, greatest at 30 ft/min, was categorized at worst as uncomfortable; sensation of thermal neutrality and comfort returned rapidly after cessation of exercise. Suggestions for further elucidation of the effects of low air velocities on thermal comfort and homeostasis include larger numbers of subjects, more extensive skin temperature measurements and more rigorous analysis of the data from this study.

  4. Dynamics of Air Temperature, Velocity and Ammonia Emissions in Enclosed and Conventional Pig Housing Systems

    PubMed Central

    Song, J. I.; Park, K.-H.; Jeon, J. H.; Choi, H. L.; Barroga, A. J.

    2013-01-01

    This study aimed to compare the dynamics of air temperature and velocity under two different ventilation and housing systems during summer and winter in Korea. The NH3 concentration of both housing systems was also investigated in relation to the pig’s growth. The ventilation systems used were; negative pressure type for the enclosed pig house (EPH) and natural airflow for the conventional pig house (CPH). Against a highly fluctuating outdoor temperature, the EPH was able to maintain a stable temperature at 24.8 to 29.1°C during summer and 17.9 to 23.1°C during winter whilst the CPH had a wider temperature variance during summer at 24.7 to 32.3°C. However, the temperature fluctuation of the CPH during winter was almost the same with that of EPH at 14.5 to 18.2°C. The NH3 levels in the CPH ranged from 9.31 to 16.9 mg/L during summer and 5.1 to 19.7 mg/L during winter whilst that of the EPH pig house was 7.9 to 16.1 mg/L and 3.7 to 9.6 mg/L during summer and winter, respectively. These values were less than the critical ammonia level for pigs with the EPH maintaining a lower level than the CPH in both winter and summer. The air velocity at pig nose level in the EPH during summer was 0.23 m/s, enough to provide comfort because of the unique design of the inlet feature. However, no air movement was observed in almost all the lower portions of the CPH during winter because of the absence of an inlet feature. There was a significant improvement in weight gain and feed intake of pigs reared in the EPH compared to the CPH (p<0.05). These findings proved that despite the difference in the housing systems, a stable indoor temperature was necessary to minimize the impact of an avoidable and highly fluctuating outdoor temperature. The EPH consistently maintained an effective indoor airspeed irrespective of season; however the CPH had defective and stagnant air at pig nose level during winter. Characteristics of airflow direction and pattern were consistent relative to

  5. Anomalous Velocity Dependence of the Friction Coefficient of an Air Supported Pulley

    NASA Astrophysics Data System (ADS)

    Crismani, Matteo; Nauenberg, Michael

    2009-11-01

    A standard undergraduate lab exercise to verify Newton's law, F = ma, is to measure the acceleration a of a glider of mass m suspended on an air track. In our experiment the glider is accelerated by a thin tape attached to the glider at one end, and to a weight of mass M at the other end. The weight hangs vertically via a pulley over which the tape is suspended by air pressure. In the absence of friction, the force pulling the glider is F = (M m/(M + m)g, where g is the acceleration of gravity. To the accuracy provided by the fast electronic timers (accurate to 1/10000 second) used in our experiment to measure the velocity and the acceleration of the glider, we verified that the friction due to the air track can be neglected. But we found that this is not the case for the friction due to the air pulley which adds a component -v/T to the force F on the glider, where T is the friction coefficient. We have measured the dependence of this coefficient on v, and found an excellent analytic fit to our data. This fit deviates considerable from the conventional assumption that 1/T is a constant and/or depends linearly on v.

  6. Velocity measurements within a shock and reshock induced air/SF6 turbulent mixing zone

    NASA Astrophysics Data System (ADS)

    Haas, Jean-Francois; Bouzgarrou, Ghazi; Bury, Yannick; Jamme, Stephane; Joly, Laurent; Shock-induced mixing Team

    2012-11-01

    A turbulent mixing zone (TMZ) is created in a shock tube (based in ISAE, DAEP) when a Mach 1.2 shock wave in air accelerates impulsively to 70 m/s an air/SF6 interface. The gases are initially separated by a 1 μm thick plastic microfilm maintained flat and parallel to the shock by two wire grids. The upper grid of square spacing 1.8 mm imposes the nonlinear initial perturbation for the Richtmyer-Meshkov instability (RMI). After interaction with a reshock and a rarefaction, the TMZ remains approximately stagnant but much more turbulent. High speed Schlieren visualizations enable the choice of abscissae for Laser Doppler Velocity (LDV) measurements. For a length of the SF6 section equal to 250 mm, the LDV abscissae are 43, 135 and 150 mm from the initial position of the interface. Because of numerous microfilm fragments in the flow and a limited number of olive oil droplets as seeding particles for the LDV, statistical convergence requires the superposition of a least 50 identical runs at each abscissa. The dependence of TMZ structure and velocity field on length of the SF6 section between 100 and 300 mm will be presented. This experimental investigation is carried out in support of modeling and multidimensional simulation efforts at CEA, DAM, DIF. Financial support from CEA is thanksfully appreciated by ISAE.

  7. Phase-resolved functional optical coherence tomography: simultaneous imaging of in situ tissue structure, blood flow velocity, standard deviation, birefringence, and Stokes vectors in human skin

    NASA Astrophysics Data System (ADS)

    Ren, Hongwu; Ding, Zhihua; Zhao, Yonghua; Miao, Jianjun; Nelson, J. Stuart; Chen, Zhongping

    2002-10-01

    We describe a phase-resolved functional optical coherence tomography system that can simultaneously yield in situ images of tissue structure, blood flow velocity, standard deviation, birefringence, and the Stokes vectors in human skin. Multifunctional images were obtained by processing of analytical interference fringe signals derived from two perpendicular polarization-detection channels. The blood flow velocity and standard deviation images were obtained by comparison of the phases from pairs of analytical signals in neighboring A-lines in the same polarization state. The analytical signals from two polarization-diversity detection channels were used to determine the four Stokes vectors for four reference polarization states. From the four Stokes vectors, the birefringence image, which is not sensitive to the orientation of the optical axis in the sample, was obtained. Multifunctional in situ images of a port wine stain birthmark in human skin are presented.

  8. Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1977-01-01

    A scanning radiometer was used to determine the effect of airstream velocity on the mean drop diameter of water sprays produced by pressure atomizing and air atomizing fuel nozzles used in previous combustion studies. Increasing airstream velocity from 23 to 53.4 meters per second reduced the Sauter mean diameter by approximately 50 percent with both types of fuel nozzles. The use of a sonic cup attached to the tip of an air assist nozzle reduced the Sauter mean diameter by approximately 40 percent. Test conditions included airstream velocities of 23 to 53.4 meters per second at 293 K and atmospheric pressure.

  9. Effect of Wind Tunnel Air Velocity on VOC Flux from Standard Solutions and CAFO Manure/Wastewater

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Researchers and practitioners have used wind tunnels and flux chambers to quantify the flux of volatile organic compounds (VOCs), ammonia, and hydrogen sulfide and estimate emission factors from animal feeding operations (AFOs) without accounting for effects of air velocity or sweep air flow rate. L...

  10. Validation of a CFD Model by Using 3D Sonic Anemometers to Analyse the Air Velocity Generated by an Air-Assisted Sprayer Equipped with Two Axial Fans

    PubMed Central

    García-Ramos, F. Javier; Malón, Hugo; Aguirre, A. Javier; Boné, Antonio; Puyuelo, Javier; Vidal, Mariano

    2015-01-01

    A computational fluid dynamics (CFD) model of the air flow generated by an air-assisted sprayer equipped with two axial fans was developed and validated by practical experiments in the laboratory. The CFD model was developed by considering the total air flow supplied by the sprayer fan to be the main parameter, rather than the outlet air velocity. The model was developed for three air flows corresponding to three fan blade settings and assuming that the sprayer is stationary. Actual measurements of the air velocity near the sprayer were taken using 3D sonic anemometers. The workspace sprayer was divided into three sections, and the air velocity was measured in each section on both sides of the machine at a horizontal distance of 1.5, 2.5, and 3.5 m from the machine, and at heights of 1, 2, 3, and 4 m above the ground The coefficient of determination (R2) between the simulated and measured values was 0.859, which demonstrates a good correlation between the simulated and measured data. Considering the overall data, the air velocity values produced by the CFD model were not significantly different from the measured values. PMID:25621611

  11. Simultaneous measurement of temperature and velocity fields in convective air flows

    NASA Astrophysics Data System (ADS)

    Schmeling, Daniel; Bosbach, Johannes; Wagner, Claus

    2014-03-01

    Thermal convective air flows are of great relevance in fundamental studies and technical applications such as heat exchangers or indoor ventilation. Since these kinds of flow are driven by temperature gradients, simultaneous measurements of instantaneous velocity and temperature fields are highly desirable. A possible solution is the combination of particle image velocimetry (PIV) and particle image thermography (PIT) using thermochromic liquid crystals (TLCs) as tracer particles. While combined PIV and PIT is already state of the art for measurements in liquids, this is not yet the case for gas flows. In this study we address the adaptation of the measuring technique to gaseous fluids with respect to the generation of the tracer particles, the particle illumination and the image filtering process. Results of the simultaneous PIV/PIT stemming from application to a fluid system with continuous air exchange are presented. The measurements were conducted in a cuboidal convection sample with air in- and outlet at a Rayleigh number Ra ≈ 9.0 × 107. They prove the feasibility of the method by providing absolute and relative temperature accuracies of σT = 0.19 K and σΔT = 0.06 K, respectively. Further open issues that have to be addressed in order to mature the technique are identified.

  12. Effects of CO2/N2 dilution on laminar burning velocity of stoichiometric DME-air mixture at elevated temperatures.

    PubMed

    Mohammed, Abdul Naseer; Juhany, Khalid A; Kumar, Sudarshan; Kishore, V Ratna; Mohammad, Akram

    2017-03-21

    The laminar burning velocity of CO2/N2 diluted stoichiometric dimethyl ether (DME) air mixtures is determined experimentally at atmospheric pressure and elevated mixture temperatures using a mesoscale high aspect-ratio diverging channel with inlet dimensions of 25mm×2mm. In this method, planar flames at different initial temperatures (Tu) were stabilized inside the channel using an external electric heater. The magnitude of burning velocities was acquired by measuring the flame position and initial temperature. The mass conservation of the mixture entering the inlet and the stationary planar flame front is applied to obtain the laminar burning velocity. Laminar burning velocity at different initial mixture temperatures is plotted with temperature ratio (Tu/Tu,o), where a reference temperature (Tu,o) of 300K is used. Enhancement in the laminar burning velocity is observed with mixture temperature for DME-air mixtures with CO2 and N2 dilutions. A significant decrease in the burning velocity and slight increase in temperature exponent of the stoichiometric DME-air mixture was observed with dilution at same temperatures. The addition of CO2 has profound influence when compared to N2 addition on both burning velocity and temperature exponent.

  13. Analysis of possible improvement of acceleration of a high-velocity air-breathing flying vehicle

    NASA Astrophysics Data System (ADS)

    Goonko, Yu. P.; Mazhul, I. I.

    2008-09-01

    Results of parametric calculations of the total aeropropulsive characteristics and characteristics of acceleration of a small-scale high-velocity flying vehicle with an air-breathing engine are presented. Integral parameters of acceleration from the flight Mach number M∞ = 4 to M∞ = 7 are determined, namely, the time required fuel stock, and range. A schematic configuration of the vehicle is considered, which allows studying the basic parameters, such as the forebody shape, the angles of surfaces of compression of the stream captured by the inlet, angles of external aerodynamic surfaces of the airframe, relative planform area of the wing panels, and relative area of the nozzle cross section. A comparative estimate of the effect of these parameters shows that it is possible to improve the characteristics of acceleration of vehicles of the type considered.

  14. Effects of light intensity and air velocity on air temperature, water vapor pressure, and CO2 concentration inside a plant canopy under an artificial lighting condition.

    PubMed

    Kitaya, Y; Shibuya, T; Kozai, T; Kubota, C

    1998-01-01

    In order to characterize environmental variables inside a plant canopy under artificial lighting in the CELSS, we investigated the effects of light intensity and air velocity on air temperature, water vapor pressure, and CO2 concentration inside a plant canopy. Under a PPF of 500 micromoles m-2 s-1, air temperature was 2-3 degrees C higher, water vapor pressure was 0.6 kPa higher, and CO2 concentration was 25-35 micromoles mol-1 lower at heights ranging from 0 to 30 mm below the canopy than at a height 60 mm above the canopy. Increasing the PPF increased air temperature and water vapor pressure and decreased CO2 concentration inside the canopy. The air temperature was lower and the CO2 concentration was higher inside the canopy at an air velocity of 0.3 m s-1 than at an air velocity of 0.1 m s-1. The environmental variables inside the canopy under a high light intensity were characterized by higher air temperature, higher vapor pressure, and lower CO2 concentration than those outside the canopy.

  15. Left atrial mechanical functions in chronic primary mitral regurgitation patients: a velocity vector imaging-based study

    PubMed Central

    Yurdakul, Selen; Yıldirimtürk, Özlem

    2014-01-01

    Introduction Assessment of the left atrium (LA) mechanical function provides further information on the level of cardiac compensation. We aimed to evaluate LA function using a strain imaging method: velocity vector imaging (VVI) in chronic primary mitral regurgitation (MR). Material and methods We recruited 48 patients with chronic, isolated, moderate to severe MR (54.70 ±15.35 years and 56% male) and 30 age- and sex-matched healthy controls (56.52 ±15.95 years and 56% male). The LA volumes during reservoir (RV), conduit (CV) and contractile phases (AV) were measured. Global strain (S), systolic strain rate (SRs), early diastolic (ESRd) and late diastolic strain rate (LSRd) were calculated. Results LA RV (50 ±18.7 to 37.9 ±5.9; p = 0.0001), CV (43.1 ±29 to 21 ±2.56; p = 0.0001), and AV (17.9 ±13.5 to 10.9 ±1.9; p = 0.006) were increased in MR patients. The LA reservoir phase strain was 16.2 ±8.1% in the MR group and 51.1 ±5.7% in the control group (p = 0.0001). The LA SRs (1.01 ±0.52 s–1 for MR and 2.1 ±0.22 s–1 for controls; p = 0.0001), LA ESRd (0.83 ±0.34 s–1 for MR and 2.26 ±0.17 s–1 for controls; p = 0.0001) and LA LSRd (0.76 ±0.24 s–1 for MR and 2.2 ±0.26 s–1 for controls; p = 0.0001) were impaired in MR patients. Conclusions The LA deformation indices may be used as adjunctive parameters to determine LA dysfunction in chronic primary MR. PMID:25097574

  16. The influence of bubble plumes on air-seawater gas transfer velocities

    SciTech Connect

    Asher, W.E.; Karle, L.M.; Higgins, B.J.

    1995-07-01

    Air-sea gas exchange is an important process in the geochemical cycling of carbon dioxide (CO{sub 2}). The air-sea flux of CO{sub 2} is determined in part by the physical forcing functions, which are parameterized in terms of the air-sea transfer velocity, k{sub L}. Past studies have attempted to correlate k{sub L} with wind speed, U. Because strong winds occur in ocean regions thought to be important sources or sinks of CO{sub 2}, accurate knowledge of k{sub L} at high U is important in estimating the global air-sea flux of CO{sub 2}. Better understanding of the physical processes affecting gas transfer at large U will increase the accuracy in estimating k{sub L} in ocean regions with high CO{sub 2}, fluxes. Increased accuracy in estimating k{sub L} will increase the accuracy in calculating the net global air-sea CO{sub 2} flux and provide more accurate boundary and initial conditions for global ocean carbon cycle models. High wind speeds are associated with the presence of whitecaps, which can increase the gas flux by generating turbulence, disrupting surface films, and creating bubble plumes. Bubble plumes will create additional turbulence, prolong the surface disruption, and transfer gas to or from individual bubbles while they are beneath the surface. These turbulence and bubble processes very effectively promote gas transfer. Because of this, it is postulated that breaking waves, if present, will dominate non-whitecap related gas exchange. Under this assumption, k{sub L} Will increase linearly with increasing fractional area whitecap coverage, W{sub c}. In support of this, researchers found k{sub L} measured in a whitecap simulation tank (WSI) was linearly correlated with bubble plume coverage, B{sub c} (the laboratory analog of W{sub c}). However, it is not definitively known how the presence of breaking waves and bubble plumes affect the dependence of k{sub L} on Schmidt number, Sc, and aqueous-phase solubility, {alpha}.

  17. A Comparison between Compounding Techniques using Large Beam-Steered Plane Wave Imaging for Blood Vector Velocity Imaging in a Carotid Artery Model.

    PubMed

    Saris, Anne; Hansen, Hendrik; Fekkes, Stein; Nillesen, Maartje; Rutten, Marcel; de Korte, Chris

    2016-09-07

    Conventional color Doppler imaging is limited, since it only provides velocity estimates along the ultrasound beam direction for a restricted field of view at a limited frame rate. High frame rate speckle tracking, using plane wave transmits, has shown potential for 2D blood velocity estimation. However, due to the lack of focusing in transmit, image quality gets reduced, which hampers speckle tracking. Although ultrafast imaging facilitates improved clutter filtering, it still remains a major challenge in blood velocity estimation. Signal drop-outs and poor velocity estimates are still present for high beam-to-flow angles and low blood flow velocities. In this work, ultrafast plane wave imaging was combined with multi-scale speckle tracking to assess the 2D blood velocity vector in a common carotid artery (CCA) flow field. A multi-angled plane wave imaging sequence was used to compare the performance of displacement compounding, coherent compounding and compound speckle tracking. Zero-degree plane wave imaging was also evaluated. The performance of the methods was evaluated before and after clutter filtering for the large range of velocities (0 to 1.5 m/s) that are normally present in a healthy CCA during the cardiac cycle. An extensive simulation study was performed, based on a sophisticated model of the CCA, to investigate and evaluate the performance of the methods at different pulse repetition frequencies and signal-to-noise levels. In vivo data were acquired of a healthy carotid artery bifurcation to support the simulation results. In general, methods utilizing compounding after speckle tracking, i.e., displacement compounding and compound speckle tracking, were least affected by clutter filtering and provided the most robust and accurate estimates for the entire velocity range. Displacement compounding, which uses solely axial information to estimate the velocity vector, provided most accurate velocity estimates, although it required sufficiently high pulse

  18. A Comparison Between Compounding Techniques Using Large Beam-Steered Plane Wave Imaging for Blood Vector Velocity Imaging in a Carotid Artery Model.

    PubMed

    Saris, Anne E C M; Hansen, Hendrik H G; Fekkes, Stein; Nillesen, Maartje M; Rutten, Marcel C M; de Korte, Chris L

    2016-11-01

    Conventional color Doppler imaging is limited, since it only provides velocity estimates along the ultrasound beam direction for a restricted field of view at a limited frame rate. High-frame-rate speckle tracking, using plane wave transmits, has shown potential for 2-D blood velocity estimation. However, due to the lack of focusing in transmit, image quality gets reduced, which hampers speckle tracking. Although ultrafast imaging facilitates improved clutter filtering, it still remains a major challenge in blood velocity estimation. Signal dropouts and poor velocity estimates are still present for high beam-to-flow angles and low blood flow velocities. In this paper, ultrafast plane wave imaging was combined with multiscale speckle tracking to assess the 2-D blood velocity vector in a common carotid artery (CCA) flow field. A multiangled plane wave imaging sequence was used to compare the performance of displacement compounding, coherent compounding, and compound speckle tracking. Zero-degree plane wave imaging was also evaluated. The performance of the methods was evaluated before and after clutter filtering for the large range of velocities (0-1.5 m/s) that are normally present in a healthy CCA during the cardiac cycle. An extensive simulation study was performed, based on a sophisticated model of the CCA, to investigate and evaluate the performance of the methods at different pulse repetition frequencies and signal-to-noise levels. In vivo data were acquired of a healthy carotid artery bifurcation to support the simulation results. In general, methods utilizing compounding after speckle tracking, i.e., displacement compounding and compound speckle tracking, were least affected by clutter filtering and provided the most robust and accurate estimates for the entire velocity range. Displacement compounding, which uses solely axial information to estimate the velocity vector, provided most accurate velocity estimates, although it required sufficiently high pulse

  19. Measuring OutdoorAir Intake Rates Using Electronic Velocity Sensors at Louvers and Downstream of Airflow Straighteners

    SciTech Connect

    Fisk, William; Sullivan, Douglas; Cohen, Sebastian; Han, Hwataik

    2008-10-01

    Practical and accurate technologies are needed for continuously measuring and controlling outdoor air (OA) intake rates in commercial building heating, ventilating, and air conditioning (HVAC) systems. This project evaluated two new measurement approaches. Laboratory experiments determined that OA flow rates were measurable with errors generally less than 10percent using electronic air velocity probes installed between OA intake louver blades or at the outlet face of louvers. High accuracy was maintained with OA flow rates as low as 15percent of the maximum for the louvers. Thus, with this measurement approach HVAC systems do not need separate OA intakes for minimum OA supply. System calibration parameters are required for each unique combination of louver type and velocity sensor location but calibrations are not necessary for each system installation. The research also determined that the accuracy of measuring OA flow rates with velocity probes located in the duct downstream of the intake louver was not improved by installing honeycomb airflow straighteners upstream of the probes. Errors varied with type of upstream louver, were as high as 100percent, and were often greater than 25percent. In conclusion, use of electronic air velocity probes between the blades of OA intake louvers or at the outlet face of louvers is a highly promising means of accurately measuring rates of OA flow into HVAC systems. The use of electronic velocity probes downstream of airflow straighteners is less promising, at least with the relatively small OA HVAC inlet systems employed in this research.

  20. An application of particle image velocimetry to the direct measurement of laminar burning velocity in homogeneous propane-air mixtures

    SciTech Connect

    Zhou, M.; Garner, C.P.

    1995-12-31

    An experiment is described for the direct measurement of laminar burning velocity within an optically accessed cylindrical combustion chamber. The laminar burning velocity was determined directly as the difference between the flame propagation speed and the unburned gas velocity immediately ahead of the flame front. Particle Image Velocimetry (PIV) has been applied to measure the unburned gas velocity field. The local flame speed and flame front position were determined from a pair of ionization probes in conjunction with the simultaneous PIV measurement. The laminar burning velocity of propane-air mixtures initially at atmospheric condition for different equivalence ratios ranging from 0.7--1.4 are presented. Close agreement with other measurements and predicted results was found.

  1. INVESTIGATING THE INFLUENCE OF RELATIVE HUMIDITY, AIR VELOCITY, AND AMPLIFICATION ON THE EMISSION RATES OF FUNGAL SPORES

    EPA Science Inventory

    The paper discusses the impact of relative humidity (RH), air velocity, and surface growth on the emission rates of fungal spores from the surface of contaminated material. Although the results show a complex interaction of factors, we have determined, for this limited data set,...

  2. Calculation and measurement of a neutral air flow velocity impacting a high voltage capacitor with asymmetrical electrodes

    SciTech Connect

    Malík, M. Primas, J.; Kopecký, V.; Svoboda, M.

    2014-01-15

    This paper deals with the effects surrounding phenomenon of a mechanical force generated on a high voltage asymmetrical capacitor (the so called Biefeld-Brown effect). A method to measure this force is described and a formula to calculate its value is also given. Based on this the authors derive a formula characterising the neutral air flow velocity impacting an asymmetrical capacitor connected to high voltage. This air flow under normal circumstances lessens the generated force. In the following part this velocity is measured using Particle Image Velocimetry measuring technique and the results of the theoretically calculated velocity and the experimentally measured value are compared. The authors found a good agreement between the results of both approaches.

  3. Determination of burst initiation location and tear propagation velocity during air burst testing of latex condoms

    NASA Astrophysics Data System (ADS)

    Davidhazy, Andrew

    1991-04-01

    The stress testing of latex condoms by an air burst procedure has been slow in gaining industry acceptance because questions have been raised regarding the influence of the test apparatus on the likelihood of breakage occurring where the condom is attached to the inflation device. It was desired to locate the areas at which the condoms tend to burst and thus corroborate or disprove these claims. Several factors associated with the bursting condom demanded the use of special instrumentation to detect arid study the burst initiation process. Microsecond duration electronic flashes were used for the initial stages of the investigation. Although the absolute point of initiation of a given burst could not be photographed, these high speed studies tend to indicate that the most likely place for high quality condoms to break is not where they are attached to the inflation device but at an intermediate area between the base and the tip of the condom. In addition, tear propagation characteristics and velocities were determined with a delayed-flash technique, a double-slit strip method and a rotating drum framing camera.

  4. Species and velocity visualization of unseeded heated air and combusting hydrogen jets using laser and flashlamp sources

    NASA Technical Reports Server (NTRS)

    Diskin, Glenn S.; Lempert, Walter R.; Miles, Richard B.

    1990-01-01

    Three techniques for the visualization of species and/or velocity in unseeded H2/air flames and heated air jets are described and preliminary image data are presented. The techniques described are: (1) simultaneous ArF laser imaging of H2, O2, and Rayleigh cross-section weighted density in an H2, O2, and Rayleigh cross-section weighted density in an H2/air flame; (2) ultraviolet flashlamp imaging of O2, OH, and Rayleigh cross-section weighted density in an H2/air flame; and (3) Raman Excitation plus Laser Induced Electronic Fluorescence velocimetry in heater air flows, up to static temperatures of 700 K. Application of these techniques, individually or in combination, should provide useful insight into mixing and reacting flows containing H2, O2, N2 and reaction intermediates such as OH.

  5. Wartime Distribution Operations: Roles of Focused Logistics, Velocity Management, Strategic Distribution Policy and Air Clearance Policy

    DTIC Science & Technology

    2004-03-19

    EFFECTIVE AND EFFICIENT ..................................................1 VELOCITY MANAGEMENT – DEFINITION AND HISTORY...achieve immediate improvements. This effort resulted in the Army adopting VM. VELOCITY MANAGEMENT – DEFINITION AND HISTORY Beginning in 1995, the Army

  6. Simultaneous measurement of temperature and velocity of air flow over 1000°C using two color phosphor thermometry

    NASA Astrophysics Data System (ADS)

    Fukuta, Masatoshi; Someya, Satoshi; Munakata, Tetsuo; LCS Team

    2016-11-01

    Thermal barrier coatings were applied to the gas turbines and the internal combustion engines for the high thermal efficiency. The evaluation and the improvement of coatings require to measure transient gaseous flow near the wall with coatings. An aim of this study is to combine a two color phosphor thermometry with the PIV to measure simultaneously temperature and velocity of the gas over 1000°C. The temperature and velocity distribution of an impinging jet of high temperature air was simultaneously visualized in experiments. The temperature was estimated from an intensity ratio of luminescent in different ranges of wavelength, 500 600 nm and 400 480 nm. Uncertainty of measured temperature was less than 10°C. Temperatures measured by the developed method and by thermocouples were agreed well. The measured velocity by the PIV with phosphor particles were also agreed well with the velocity measured by a Laser Doppler Velocimeter.

  7. Step-Wise Velocity of an Air Bubble Rising in a Vertical Tube Filled with a Liquid Dispersion of Nanoparticles.

    PubMed

    Cho, Heon Ki; Nikolov, Alex D; Wasan, Darsh T

    2017-03-21

    The motion of air bubbles in tubes filled with aqueous suspensions of nanoparticles (nanofluids) is of practical interest for bubble jets, lab-on-a-chip, and transporting media. Therefore, the focus of this study is the dynamics of air bubbles rising in a tube in a nanofluid. Many authors experimentally and analytically proposed that the velocity of rising air bubbles is constant for long air bubbles suspended in a vertical tube in common liquids (e.g. an aqueous glycerol solution) when the capillary number is larger than 10(-4). For the first time, we report here a systematic study of an air bubble rising in a vertical tube in a nanofluid (e.g. an aqueous silica dioxide nanoparticle suspension, nominal particle size, 19 nm). We varied the bubble length scaled by the diameter of the tubes (L/D), the concentration of the nanofluid (10 and 12.5 v %), and the tube diameter (0.45, 0.47, and 0.50 cm). The presence of the nanoparticles creates a significant change in the bubble velocity compared with the bubble rising in the common liquid with the same bulk viscosity. We observed a novel phenomenon of a step-wise increase in the air bubble rising velocity versus bubble length for small capillary numbers less than 10(-7). This step-wise velocity increase versus the bubble length was not observed in a common fluid. The step-wise velocity increase is attributed to the nanoparticle self-layering phenomenon in the film adjacent to the tube wall. To elucidate the role of the nanoparticle film self-layering on the bubble rising velocity, the effect of the capillary number, the tube diameter (e.g. the capillary pressure), and nanofilm viscosity are investigated. We propose a model that takes into consideration the nanoparticle layering in the film confinement to explain the step-wise velocity phenomenon versus the length of the bubble. The oscillatory film interaction energy isotherm is calculated and the Frenkel approach is used to estimate the film viscosity.

  8. Carbon isotope evidence for the latitudinal distribution and wind speed dependence of the air-sea gas transfer velocity

    NASA Astrophysics Data System (ADS)

    Krakauer, Nir Y.; Randerson, James T.; Primeau, François W.; Gruber, Nicolas; Menemenlis, Dimitris

    2006-11-01

    The air-sea gas transfer velocity is an important determinant of the exchange of gases, including CO2, between the atmosphere and ocean, but the magnitude of the transfer velocity and what factors control it remains poorly known. Here, we use oceanic and atmospheric observations of 14C and 13C to constrain the global mean gas transfer velocity as well as the exponent of its wind speed dependence, utilizing the distinct signatures left by the air-sea exchange of 14CO2 and 13CO2. While the atmosphere and ocean inventories of 14CO2 and 13CO2 constrain the mean gas transfer velocity, the latitudinal pattern in the atmospheric and oceanic 14C and 13C distributions contain information about the wind speed dependence. We computed the uptake of bomb 14C by the ocean for different transfer velocity patterns using pulse response functions from an ocean general circulation model, and evaluated the match between the predicted bomb 14C concentrations and observationally based estimates for the 1970s-1990s. Using a wind speed climatology based on satellite measurements, we solved either for the best-fit global relationship between gas exchange and mean wind speed or for the mean gas transfer velocity over each of 11 ocean regions. We also compared the predicted consequences of different gas exchange relationships on the rate of change and interhemisphere gradient of 14C in atmospheric CO2 with tree-ring and atmospheric measurements. Our results suggest that globally, the dependence of the air-sea gas transfer velocity on wind speed is close to linear, with an exponent of 0.5 +/- 0.4, and that the global mean gas transfer velocity at a Schmidt number of 660 is 20 +/- 3 cm/hr, similar to the results of previous analyses. We find that the air-sea flux of 13C estimated from atmosphere and ocean observations also suggests a lower than quadratic dependence of gas exchange on wind speed.

  9. Simulation comparison of a decoupled longitudinal control system and a velocity vector control wheel steering system during landings in wind shear

    NASA Technical Reports Server (NTRS)

    Kimball, G., Jr.

    1980-01-01

    A simulator comparison of the velocity vector control wheel steering (VCWS) system and a decoupled longitudinal control system is presented. The piloting task was to use the electronic attitude direction indicator (EADI) to capture and maintain a 3 degree glide slope in the presence of wind shear and to complete the landing using the perspective runway included on the EADI. The decoupled control system used constant prefilter and feedback gains to provide steady state decoupling of flight path angle, pitch angle, and forward velocity. The decoupled control system improved the pilots' ability to control airspeed and flight path angle during the final stages of an approach made in severe wind shear. The system also improved their ability to complete safe landings. The pilots preferred the decoupled control system in severe winds and, on a pilot rating scale, rated the approach and landing task with the decoupled control system as much as 3 to 4 increments better than use of the VCWS system.

  10. Performance of a Compression-ignition Engine with a Precombustion Chamber Having High-Velocity Air Flow

    NASA Technical Reports Server (NTRS)

    Spanogle, J A; Moore, C S

    1931-01-01

    Presented here are the results of performance tests made with a single-cylinder, four stroke cycle, compression-ignition engine. These tests were made on a precombustion chamber type of cylinder head designed to have air velocity and tangential air flow in both the chamber and cylinder. The performance was investigated for variable load and engine speed, type of fuel spray, valve opening pressure, injection period and, for the spherical chamber, position of the injection spray relative to the air flow. The pressure variations between the pear-shaped precombustion chamber and the cylinder for motoring and full load conditions were determined with a Farnboro electric indicator. The combustion chamber designs tested gave good mixing of a single compact fuel spray with the air, but did not control the ensuing combustion sufficiently. Relative to each other, the velocity of air flow was too high, the spray dispersion by injection too great, and the metering effect of the cylinder head passage insufficient. The correct relation of these factors is of the utmost importance for engine performance.

  11. Computer Simulation of Strong Ground Motion near a Fault Using Dynamic Fault Rupture Modeling: Spatial Distribution of the Peak Ground Velocity Vectors

    NASA Astrophysics Data System (ADS)

    Miyatake, T.

    Computer simulation was used to study the nature of the strong ground motion near a strike-slip fault. The faulting process was modeled by stress release with fixed rupture velocity in a uniform elastic half-space or layered half-space. The fourth-order 3-D finite-difference method with staggered grids was employed to compute both ground motions and slip histories on the fault. The fault rupture was assumed to start from a point and propagate circularly with 0.8 times shear-wave velocity. In the present paper, we focused on the spatial pattern of ground velocity vectors, i.e., the direction of strong motions. In the case of bilateral rupture propagation, the strong fault parallel ground motion appeared near the center of the fault. The fault normal motions of ground velocity appeared near the edges of the fault. In the case of unilateral rupture, the fault parallel motion appeared near the starting point however, the amplitude was lower than that for the bilateral rupture case. The fault normal motion was predominant near the terminal point of the rupture. The results were applied to the earthquake damage data, especially the directions that simple bodies overturned and wooden houses collapsed, caused by the 1927 Tango, the 1930 Kita-Izu, and the 1948 Fukui earthquakes. The spatial distributions of the direction data were found to reflect the strong ground motions generated from the earthquake source process.

  12. Group-phase Velocity Difference and THz Oscillation of the Nonlinear Refractive Index in Air: Particle-like Solutions

    SciTech Connect

    Kovachev, L. M.

    2009-10-29

    We present an analytical approach to the theory of optical pulses with superbroad spectrum propagated in air. The corresponding modified amplitude envelope equation admits oscillated with terahertz frequency nonlinear term The fluctuation is due to the group and phase velocity difference. In the partial case of femtosecond pulses with power, little above the critical for self-focusing, exact (3+1)D particle-like solution is found.

  13. Anomalous high-velocity outbursts ejected from the surface of tungsten microdroplets in a flow of argon-air plasma

    NASA Astrophysics Data System (ADS)

    Gulyaev, I. P.; Dolmatov, A. V.; Gulyaev, P. Yu; Iordan, V. I.; Kharlamov, M. Yu; Krivtsun, I. V.

    2016-02-01

    For the first time, a phenomenon of high-velocity outbursts ejected from the surface of liquid tungsten microparticles in a flow of argon-air plasma under atmospheric pressure was observed. As tungsten particles sized 50 to 200 μm moved in a plasma flow, stratified radiating spheres up to 9 mm in diameter formed around such particles. The spheres were sources of high-velocity outbursts whose ejection direction coincided with the direction of the plasma flow. The velocity of the anomalous outbursts amounted to 3-20 km/s. In the outburst images, the distribution of glow intensity along outburst tracks exhibited a wavy decaying behavior with a wavelength of 5-15 mm. Possible physical factors that could be the cause of the phenomenon are discussed.

  14. Influence of current velocity and wind speed on air-water gas exchange in a mangrove estuary

    NASA Astrophysics Data System (ADS)

    Ho, David T.; Coffineau, Nathalie; Hickman, Benjamin; Chow, Nicholas; Koffman, Tobias; Schlosser, Peter

    2016-04-01

    Knowledge of air-water gas transfer velocities and water residence times is necessary to study the fate of mangrove derived carbon exported into surrounding estuaries and ultimately to determine carbon balances in mangrove ecosystems. For the first time, the 3He/SF6 dual tracer technique, which has been proven to be a powerful tool to determine gas transfer velocities in the ocean, is applied to Shark River, an estuary situated in the largest contiguous mangrove forest in North America. The mean gas transfer velocity was 3.3 ± 0.2 cm h-1 during the experiment, with a water residence time of 16.5 ± 2.0 days. We propose a gas exchange parameterization that takes into account the major sources of turbulence in the estuary (i.e., bottom generated shear and wind stress).

  15. Combustion Velocity of Benzine-Benzol-Air Mixtures in High-Speed Internal-Combustion Engines

    NASA Technical Reports Server (NTRS)

    Schnauffer, Kurt

    1932-01-01

    The present paper describes a device whereby rapid flame movement within an internal-combustion engine cylinder may be recorded and determined. By the aid of a simple cylindrical contact and an oscillograph the rate of combustion within the cylinder of an airplane engine during its normal operation may be measured for gas intake velocities of from 30 to 35 m/s and for velocities within the cylinder of from 20 to 25 m/s. With it the influence of mixture ratios, of turbulence, of compression ratio and kind of fuel on combustion velocity may be determined. Besides the determination of the influence of the above factors on combustion velocity, the degree of turbulence may also be determined. As a unit of reference in estimating the degree of turbulence, the intake velocity of the charge is chosen.

  16. Spatially and Temporally Resolved Measurements of Velocity in a H2-air Combustion-Heated Supersonic Jet

    NASA Technical Reports Server (NTRS)

    Bivolaru, Daniel; Cutler, Andrew D.; Danehy, Paul M.; Gaffney, Richard L.; Baurle, Robert a.

    2009-01-01

    This paper presents simultaneous measurements at multiple points of two orthogonal components of flow velocity using a single-shot interferometric Rayleigh scattering (IRS) technique. The measurements are performed on a large-scale Mach 1.6 (Mach 5.5 enthalpy) H2-air combustion jet during the 2007 test campaign in the Direct Connect Supersonic Combustion Test facility at NASA Langley Research Center. The measurements are performed simultaneously with CARS (Coherent Anti-stokes Raman Spectroscopy) using a combined CARS-IRS instrument with a common path 9-nanosecond pulsed, injection-seeded, 532-nm Nd:YAG laser probe pulse. The paper summarizes the measurements of velocities along the core of the vitiated air flow as well as two radial profiles. The average velocity measurement near the centerline at the closest point from the nozzle exit compares favorably with the CFD calculations using the VULCAN code. Further downstream, the measured axial velocity shows overall higher values than predicted with a trend of convergence at further distances. Larger discrepancies are shown in the radial profiles.

  17. 3D Position and Velocity Vector Computations of Objects Jettisoned from the International Space Station Using Close-Range Photogrammetry Approach

    NASA Technical Reports Server (NTRS)

    Papanyan, Valeri; Oshle, Edward; Adamo, Daniel

    2008-01-01

    Measurement of the jettisoned object departure trajectory and velocity vector in the International Space Station (ISS) reference frame is vitally important for prompt evaluation of the object s imminent orbit. We report on the first successful application of photogrammetric analysis of the ISS imagery for the prompt computation of the jettisoned object s position and velocity vectors. As post-EVA analyses examples, we present the Floating Potential Probe (FPP) and the Russian "Orlan" Space Suit jettisons, as well as the near-real-time (provided in several hours after the separation) computations of the Video Stanchion Support Assembly Flight Support Assembly (VSSA-FSA) and Early Ammonia Servicer (EAS) jettisons during the US astronauts space-walk. Standard close-range photogrammetry analysis was used during this EVA to analyze two on-board camera image sequences down-linked from the ISS. In this approach the ISS camera orientations were computed from known coordinates of several reference points on the ISS hardware. Then the position of the jettisoned object for each time-frame was computed from its image in each frame of the video-clips. In another, "quick-look" approach used in near-real time, orientation of the cameras was computed from their position (from the ISS CAD model) and operational data (pan and tilt) then location of the jettisoned object was calculated only for several frames of the two synchronized movies. Keywords: Photogrammetry, International Space Station, jettisons, image analysis.

  18. Effect of the borax mass and pre-spray medium temperature on droplet size and velocity vector distributions of intermittently sprayed starchy solutions.

    PubMed

    Naz, Muhammad Yasin; Sulaiman, Shaharin Anwar; Ariwahjoedi, Bambang

    2015-02-07

    Spray coating technology has demonstrated great potential in the slow release fertilizers industry. The better understanding of the key spray parameters benefits both the environment and low cost coating processes. The use of starch based materials to coat the slow release fertilizers is a new development. However, the hydraulic spray jet breakup of the non-Newtonian starchy solutions is a complex phenomenon and very little known. The aim of this research was to study the axial and radial distributions of the Sauter Mean Diameter (SMD) and velocity vectors in pulsing spray patterns of native and modified tapioca starch solutions. To meet the objective, high speed imaging and Phase Doppler Anemometry (PDA) techniques were employed to characterize the four compositions of the starch-urea-borax complex namely S0, S1, S2 and S3. The unheated solutions exhibited very high viscosities ranging from 2035 to 3030 cP. No jet breakup was seen at any stage of the nozzle operation at an injection pressure of 1-5 bar. However, at 80 °C temperature and 5 bar pressure, the viscosity was reduced to 455 to 638 cP and dense spray patterns emerged from the nozzle obscuring the PDA signals. The axial size distribution revealed a significant decrease in SMD along the spray centreline. The smallest axial SMD (51 to 79 μm) was noticed in S0 spray followed by S1, S2 and S3. Unlikely, the radial SMD in S0 spray did not vary significantly at any stage of the spray injection. This trend was attributed to the continuous growth of the surface wave instabilities on the native starch sheet. However, SMD obtained with S1, S2 and S3 varied appreciably along the radial direction. The mean velocity vector profiles followed the non-Gaussian distribution. The constant vector distributions were seen in the near nozzle regions, where the spray was in the phase of development. In far regions, the velocity vectors were poly-dispersed and a series of ups and downs were seen in the respective radial

  19. Tunable diode laser absorption sensor for temperature and velocity measurements of O2 in air flows

    NASA Technical Reports Server (NTRS)

    Philippe, L. C.; Hanson, R. K.

    1991-01-01

    A fast and nonintrusive velocity and temperature diagnostic based on oxygen absorption is presented. The system uses a GaAlAs tunable diode laser, ramped and modulated in wavelength at high frequency. Detection is performed at twice the modulating frequency, leading to second harmonic absorption lineshapes. Velocity is inferred from the wavelength shift of the absorption line center due to the Doppler effect. Temperature is determined by comparing experimental and calculated lineshapes. Capabilities of the technique for studies of transient high-speed flows are demonstrated in shock tube experiments. Good agreement is obtained with predicted temperatures and velocities when pressure-induced shifts are accounted for.

  20. Increased Air Velocity Reduces Thermal and Cardiovascular Strain in Young and Older Males during Humid Exertional Heat Stress.

    PubMed

    Wright Beatty, Heather E; Hardcastle, Stephen G; Boulay, Pierre; Flouris, Andreas D; Kenny, Glen P

    2015-01-01

    Older adults have been reported to have a lower evaporative heat loss capacity than younger adults during exercise when full sweat evaporation is permitted. However, it is unclear how conditions of restricted evaporative and convective heat loss (i.e., high humidity, clothing insulation) alter heat stress. to the purpose of this study was to examine the heat stress responses of young and older males during and following exercise in a warm/humid environment under two different levels of air velocity. Ten young (YOUNG: 24±2 yr) and 10 older (OLDER: 59±3 yr) males, matched for body surface area performed 4×15-min cycling bouts (15-min rest) at a fixed rate of heat production (400 W) in warm/humid conditions (35°C, 60% relative humidity) under 0.5 (Low) and 3.0 (High) m·s(-1) air velocity while wearing work coveralls. Rectal (Tre) and mean skin (MTsk) temperatures, heart rate (HR), local sweat rate, % max skin blood flow (SkBF) (recovery only), and blood pressure (recovery only) were measured. High air velocity reduced core and skin temperatures (p < 0.05) equally in YOUNG and OLDER males (p > 0.05) but was more effective in reducing cardiovascular strain (absolute and % max HR; p < 0.05) in YOUNG males (p < 0.05). Greater increases in local dry heat loss responses (% max SkBF and cutaneous vascular conductance) were detected across time in OLDER than YOUNG males in both conditions (p < 0.05). Local dry heat loss responses and cardiovascular strain were attenuated during the High condition in YOUNG compared to OLDER (p < 0.05). High air velocity reduced the number of males surpassing the 38.0°C Tre threshold from 90% (Low) to 50% (High). Despite age-related local heat loss differences, YOUNG and OLDER males had similar levels of heat stress during intermittent exercise in warm and humid conditions while wearing work coveralls. Increased air velocity was effective in reducing heat stress equally, and cardiovascular strain to a greater extent, in YOUNG and OLDER

  1. The US Air Force Aerial Spray Unit: a history of large area disease vector control operations, WWII through Katrina.

    PubMed

    Breidenbaugh, Mark; Haagsma, Karl

    2008-01-01

    The US Air Force has had a long history of aerial applications of pesticides to fulfill a variety of missions, the most important being the protection of troops through the minimization of arthropod vectors capable of disease transmission. Beginning in World War II, aerial application of pesticides by the military has effectively controlled vector and nuisance pest populations in a variety of environments. Currently, the military aerial spray capability resides in the US Air Force Reserve (USAFR), which operates and maintains C-130 airplanes capable of a variety of missions, including ultra low volume applications for vector and nuisance pests, as well as higher volume aerial applications of herbicides and oil-spill dispersants. The USAFR aerial spray assets are the only such fixed-wing aerial spray assets within the Department of Defense. In addition to troop protection, the USAFR Aerial Spray Unit has participated in a number of humanitarian/relief missions, most recently in the response to the 2005 Hurricanes Katrina and Rita, which heavily damaged the Gulf Coasts of Louisiana, Mississippi, and Texas. This article provides historical background on the Air Force Aerial Spray Unit and describes the operations in Louisiana in the aftermath of Hurricane Katrina.

  2. Threshold velocities for input of soil particles into the air by desert soils

    SciTech Connect

    Gillette, D.A.; Adams, J.; Endo, A.; Smith, D.; Kihl, R.

    1980-10-20

    Desert soils mostly from the Mojave Desert were tested for threshold friction velocity (the friction velocity above which soil erosion takes place) with an open-bottomed portable wind tunnel. Several geomorphological settings were chosen to be representative of much of the surface of the Mojave Desert, for example, playas, alluvial fans, and aeolian features. Variables which increase threshold velocity are decreasing proportion of sand, increasing size of dry aggregates of the soil, and increasing fraction of the soil mass larger than 1 mm. Threshold velocity increases with different types of soil surfaces in the following order: disturbed soils (except disturbed heavy clay soils), sand dunes, alluvial and aeolian sand deposits, disturbed playa soils, skirts of playas, playa centers, and desert pavement (alluvial deposits). 21 references, 5 figures, 6 tables.

  3. A pulsed wire probe for the measurement of velocity and flow direction in slowly moving air.

    PubMed

    Olson, D E; Parker, K H; Snyder, B

    1984-02-01

    This report describes the theory and operation of a pulsed-probe anemometer designed to measure steady three-dimensional velocity fields typical of pulmonary tracheo-bronchial airflows. Local velocities are determined by measuring the transport time and orientation of a thermal pulse initiated at an upstream wire and sensed at a downstream wire. The transport time is a reproducible function of velocity and the probe wire spacing, as verified by a theoretical model of convective heat transfer. When calibrated the anemometer yields measurements of velocity accurate to +/- 5 percent and resolves flow direction to within 1 deg at airspeeds greater than or equal to 10 cm/s. Spatial resolution is +/- 0.5 mm. Measured flow patterns typical of curved circular pipes are included as examples of its application.

  4. Threshold velocities for input of soil particles into the air by desert soils

    NASA Astrophysics Data System (ADS)

    Gillette, Dale A.; Adams, John; Endo, Albert; Smith, Dudley; Kihl, Rolf

    1980-10-01

    Desert soils mostly from the Mojave Desert were tested for threshold friction velocity (the friction velocity above which soil erosion takes place) with an open-bottomed portable wind tunnel. Several geomorphological settings were chosen to be representative of much of the surface of the Mojave Desert, for example, playas, alluvial fans, and aeolian features. Variables which increase threshold velocity are decreasing proportion of sand, increasing size of dry aggregates of the soil, and increasing fraction of the soil mass larger than 1 mm. Threshold velocity increases with different types of soil surfaces in the following order: distrubed soils (except disturbed heavy clay soils), sand dunes, alluvial and aeolian sand deposits, disturbed playa soils, skirts of playas, playa centers, and desert pavements (alluvial deposits).

  5. Measurements of the Air-flow Velocity in the Cylinder of an Airplane Engine

    NASA Technical Reports Server (NTRS)

    Wenger, Hermann

    1939-01-01

    The object of the present investigation is to determine the velocity in the BMW-VI cylinder of an externally driven single-cylinder test engine at high engine speeds using the hot-wire method of Ulsamer.

  6. Retrieval of Raindrop Size Distribution, Vertical Air Velocity and Water Vapor Attenuation Using Dual-Wavelength Doppler Radar Observations

    NASA Technical Reports Server (NTRS)

    Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; Srivastava, C.

    2005-01-01

    Two techniques for retrieving the slope and intercept parameters of an assumed exponential raindrop size distribution (RSD), vertical air velocity, and attenuation by precipitation and water vapor in light stratiform rain using observations by airborne, nadir looking dual-wavelength (X-band, 3.2 cm and W-band, 3.2 mm) radars are presented. In both techniques, the slope parameter of the RSD and the vertical air velocity are retrieved using only the mean Doppler velocities at the two wavelengths. In the first method, the intercept of the RSD is estimated from the observed reflectivity at the longer wavelength assuming no attenuation at that wavelength. The attenuation of the shorter wavelength radiation by precipitation and water vapor are retrieved using the observed reflectivity at the shorter wavelength. In the second technique, it is assumed that the longer wavelength suffers attenuation only in the melting band. Then, assuming a distribution of water vapor, the melting band attenuation at both wavelengths and the rain attenuation at the shorter wavelength are retrieved. Results of the retrievals are discussed and several physically meaningful results are presented.

  7. Effect of flow velocity and temperature on ignition characteristics in laser ignition of natural gas and air mixtures

    NASA Astrophysics Data System (ADS)

    Griffiths, J.; Riley, M. J. W.; Borman, A.; Dowding, C.; Kirk, A.; Bickerton, R.

    2015-03-01

    Laser induced spark ignition offers the potential for greater reliability and consistency in ignition of lean air/fuel mixtures. This increased reliability is essential for the application of gas turbines as primary or secondary reserve energy sources in smart grid systems, enabling the integration of renewable energy sources whose output is prone to fluctuation over time. This work details a study into the effect of flow velocity and temperature on minimum ignition energies in laser-induced spark ignition in an atmospheric combustion test rig, representative of a sub 15 MW industrial gas turbine (Siemens Industrial Turbomachinery Ltd., Lincoln, UK). Determination of minimum ignition energies required for a range of temperatures and flow velocities is essential for establishing an operating window in which laser-induced spark ignition can operate under realistic, engine-like start conditions. Ignition of a natural gas and air mixture at atmospheric pressure was conducted using a laser ignition system utilizing a Q-switched Nd:YAG laser source operating at 532 nm wavelength and 4 ns pulse length. Analysis of the influence of flow velocity and temperature on ignition characteristics is presented in terms of required photon flux density, a useful parameter to consider during the development laser ignition systems.

  8. Studying the impact of air/brine displacement on acoustic velocities in carbonates. El Amin Mokhtar and Sandra Vega

    NASA Astrophysics Data System (ADS)

    Mokhtar, E.; Vega, D.

    2012-12-01

    The impact of air/brine displacement on acoustic velocities of carbonate rocks is not fully comprehended yet. In order to improve our understanding of this effect, we conducted laboratory measurements of porosity and acoustic velocities (Vp and Vs) under both dry and brine saturated conditions at ambient pressure and temperature. The core plug samples in this study were collected from a hydrocarbon reservoir in the Middle East. A petrographic analysis was also performed on thin sections taken from the core plugs using a microscope and a digital camera. The aim of this analysis was to study depositional facies and the extent of diagenetic overprint that caused the observed variations in rock fabrics. Cross-plots were generated to analyze the trends of behavior between acoustic velocities and porosities taking into account the influence of different rock fabrics, in both dry and brine saturated samples. Acoustic velocities of brine saturated samples were higher than velocities of dry samples, as expected. However, their differences also respond to both, total porosity and carbonate rock fabrics. This result can be attributed to the different carbonate pore structures and rock frames formed during deposition and diagenesis. Similarly, the Vp/Vs ratio cross-plots display an increase in Vp/Vs ratios for the brine saturated samples compared to the dry ones. In conclusion, differences in acoustic velocities between dry and brine saturated carbonate rocks seem to be highly effected by porosity, rock fabric, and fluid content. This information can help to better understand the differences in acoustic response between gas and brine saturated zones in well logs and seismic.

  9. Noncoplanar minimum delta V two-impulse and three-impulse orbital transfer from a regressing oblate earth assembly parking ellipse onto a flyby trans-Mars asymptotic velocity vector.

    NASA Technical Reports Server (NTRS)

    Bean, W. C.

    1971-01-01

    Comparison of two-impulse and three-impulse orbital transfer, using data from a 63-case numerical study. For each case investigated for which coplanarity of the regressing assembly parking ellipse was attained with the target asymptotic velocity vector, a two-impulse maneuver (or a one-impulse equivalent) was found for which the velocity expenditure was within 1% of a reference absolute minimum lower bound. Therefore, for the coplanar cases, use of a minimum delta-V three-impulse maneuver afforded scant improvement in velocity penalty. However, as the noncoplanarity of the parking ellipse and the target asymptotic velocity vector increased, there was a significant increase in the superiority of minimum delta-V three-impulse maneuvers for slowing the growth of velocity expenditure. It is concluded that a multiple-impulse maneuver should be contemplated if nonnominal launch conditions could occur.

  10. Simultaneous measurements of air-sea gas transfer velocity and near surface turbulence at low to moderate winds (Invited)

    NASA Astrophysics Data System (ADS)

    Wang, B.; Liao, Q.; Fillingham, J. H.; Bootsma, H. A.

    2013-12-01

    Parameterization of air-sea gas transfer velocity was routinely made with wind speed. Near surface turbulent dissipation rate has been shown to have better correlation with the gas transfer velocity in a variety of aquatic environments (i.e., the small eddy model) while wind speed is low to moderate. Wind speed model may underestimate gas transfer velocity at low to moderate winds when the near surface turbulence is produced by other environmental forcing. We performed a series of field experiments to measure the CO2 transfer velocity, and the statistics of turbulence immediately below the air-water interface using a novel floating PIV and chamber system. The small eddy model was evaluated and the model coefficient was found to be a non-constant, and it varies with the local turbulent level (figure 1). Measure results also suggested an appropriate scaling of the vertical dissipation profile immediately below the interface under non-breaking conditions, which can be parameterized by the wind shear, wave height and wave age (figure 2). Figure 1. Relation between the coefficient of the small eddy model and dissipation rate. The data also include Chu & Jirka (2003) and Vachon et al. (2010). The solid regression line: α = 0.188log(ɛ)+1.158 Figure 2. Non-dimensional dissipation profiles. Symbols: measured data with the floating PIV. Solid line: regression of measured data with a -0.79 decaying rate. Dash line with -2 slope: Terray et al. (1996) relation. Dash line with two layer structure: Siddiqui & Loewen (2007) relation.

  11. Interstellar Neutral Helium in the Heliosphere from IBEX Observations. III. Mach Number of the Flow, Velocity Vector, and Temperature from the First Six Years of Measurements

    NASA Astrophysics Data System (ADS)

    Bzowski, M.; Swaczyna, P.; Kubiak, M. A.; Sokół, J. M.; Fuselier, S. A.; Galli, A.; Heirtzler, D.; Kucharek, H.; Leonard, T. W.; McComas, D. J.; Möbius, E.; Schwadron, N. A.; Wurz, P.

    2015-10-01

    We analyzed observations of interstellar neutral helium (ISN He) obtained from the Interstellar Boundary Explorer (IBEX) satellite during its first six years of operation. We used a refined version of the ISN He simulation model, presented in the companion paper by Sokół et al. (2015b), along with a sophisticated data correlation and uncertainty system and parameter fitting method, described in the companion paper by Swaczyna et al. We analyzed the entire data set together and the yearly subsets, and found the temperature and velocity vector of ISN He in front of the heliosphere. As seen in the previous studies, the allowable parameters are highly correlated and form a four-dimensional tube in the parameter space. The inflow longitudes obtained from the yearly data subsets show a spread of ˜6°, with the other parameters varying accordingly along the parameter tube, and the minimum χ2 value is larger than expected. We found, however, that the Mach number of the ISN He flow shows very little scatter and is thus very tightly constrained. It is in excellent agreement with the original analysis of ISN He observations from IBEX and recent reanalyses of observations from Ulysses. We identify a possible inaccuracy in the Warm Breeze parameters as the likely cause of the scatter in the ISN He parameters obtained from the yearly subsets, and we suppose that another component may exist in the signal or a process that is not accounted for in the current physical model of ISN He in front of the heliosphere. From our analysis, the inflow velocity vector, temperature, and Mach number of the flow are equal to λISNHe = 255.°8 ± 0.°5, βISNHe = 5.°16 ± 0.°10, TISNHe = 7440 ± 260 K, vISNHe = 25.8 ± 0.4 km s-1, and MISNHe = 5.079 ± 0.028, with uncertainties strongly correlated along the parameter tube.

  12. Evaluation of Right Ventricular Myocardial Mechanics using Velocity Vector Imaging of Cardiac MRI Cine Images in Transposition of the Great Arteries Following Atrial and Arterial Switch Operations

    PubMed Central

    Thattaliyath, Bijoy D.; Forsha, Daniel E.; Stewart, Chad; Barker, Piers C.A.; Campbell, Michael J.

    2016-01-01

    Objective The aim of the study was to determine right and left ventricle deformation parameters in patients with transposition of the great arteries who had undergone atrial or arterial switch procedures. Setting Patients with transposition are born with a systemic right ventricle. Historically, the atrial switch operation, in which the right ventricle remains the systemic ventricle, was performed. These patients have increased rates of morbidity and mortality. We used cardiac MRI with Velocity Vector Imaging analysis to characterize and compare ventricular myocardial deformation in patients who had an atrial switch or arterial switch operation. Design Patients with a history of these procedures, who had a clinically ordered cardiac MRI were included in the study. Consecutive 20 patients (75% males, 28.7±1.8 years) who underwent atrial switch operation and 20 patients (60% males, 17.7±1.9 years) who underwent arterial switch operation were included in the study. Four chamber and short-axis cine images were used to determine longitudinal and circumferential strain and strain rate using Vector Velocity Imaging software. Results Compared to the arterial switch group, the atrial switch group had decreased right ventricular ejection fraction and increased end-diastolic and end-systolic volumes; and no difference in left ventricular ejection fraction and volumes. The atrial switch group had decreased longitudinal and circumferential strain and strain rate. When compared to normal controls multiple strain parameters in the atrial switch group were reduced. Conclusions Myocardial deformation analysis of transposition patients reveals a reduction of right ventricular function and decreased longitudinal and circumferential strain parameters in patients with an atrial switch operation compared to those with arterial switch operation. A better understanding of the mechanisms of RV failure in TGA may lead to improved therapies and adaptation. PMID:25655213

  13. Size and Velocity Characteristics of Droplets Generated by Thin Steel Slab Continuous Casting Secondary Cooling Air-Mist Nozzles

    NASA Astrophysics Data System (ADS)

    Minchaca M, J. I.; Castillejos E, A. H.; Acosta G, F. A.

    2011-06-01

    Direct spray impingement of high temperature surfaces, 1473 K to 973 K (1200 °C to 700 °C), plays a critical role in the secondary cooling of continuously cast thin steel slabs. It is known that the spray parameters affecting the local heat flux are the water impact flux w as well as the droplet velocity and size. However, few works have been done to characterize the last two parameters in the case of dense mists ( i.e., mists with w in the range of 2 to 90 L/m2s). This makes it difficult to rationalize how the nozzle type and its operating conditions must be selected to control the cooling process. In the present study, particle/droplet image analysis was used to determine the droplet size and velocity distributions simultaneously at various locations along the major axis of the mist cross section at a distance where the steel strand would stand. The measurements were carried out at room temperature for two standard commercial air-assisted nozzles of fan-discharge type operating over a broad range of conditions of practical interest. To achieve statistically meaningful samples, at least 6000 drops were analyzed at each location. Measuring the droplet size revealed that the number and volume frequency distributions were fitted satisfactorily by the respective log-normal and Nukiyama-Tanasawa distributions. The correlation of the parameters of the distribution functions with the water- and air-nozzle pressures allowed for reasonable estimation of the mean values of the size of the droplets generated. The ensemble of measurements across the mist axis showed that the relationship between the droplet velocity and the diameter exhibited a weak positive correlation. Additionally, increasing the water flow rate at constant air pressure caused a decrease in the proportion of the water volume made of finer droplets, whereas the volume proportion of faster droplets augmented until the water flow reached a certain value, after which it decreased. Diminishing the air

  14. Air Reactions to Objects Moving at Rates Above the Velocity of Sound with Application to the Air Propeller

    NASA Technical Reports Server (NTRS)

    Reed, S Albert

    1922-01-01

    There has been a tradition general among aeronautical engineers that a critical point exists for tip speeds at or near the velocity of sound, indicating a physical limit in the use of propellers at higher tip speeds; the idea being that something would occur analogous to what is known in marine propellers as cavitation. In the examination of the physics pertaining to both propellers and projectiles moving at or above 1100 feet per second, the conclusion was reached by the author that there is no reason for the existence of such a critical point and that, if it had been noted by observers it was not inherent in the phenomena revealed, but rather due to a particular shape or proportion of the projectile and that, with properly proportioned sections, it would not exist.

  15. Computational fluid dynamics investigation of human aspiration in low velocity air: orientation effects on nose-breathing simulations.

    PubMed

    Anderson, Kimberly R; Anthony, T Renée

    2014-06-01

    An understanding of how particles are inhaled into the human nose is important for developing samplers that measure biologically relevant estimates of exposure in the workplace. While previous computational mouth-breathing investigations of particle aspiration have been conducted in slow moving air, nose breathing still required exploration. Computational fluid dynamics was used to estimate nasal aspiration efficiency for an inhaling humanoid form in low velocity wind speeds (0.1-0.4 m s(-1)). Breathing was simplified as continuous inhalation through the nose. Fluid flow and particle trajectories were simulated over seven discrete orientations relative to the oncoming wind (0, 15, 30, 60, 90, 135, 180°). Sensitivities of the model simplification and methods were assessed, particularly the placement of the recessed nostril surface and the size of the nose. Simulations identified higher aspiration (13% on average) when compared to published experimental wind tunnel data. Significant differences in aspiration were identified between nose geometry, with the smaller nose aspirating an average of 8.6% more than the larger nose. Differences in fluid flow solution methods accounted for 2% average differences, on the order of methodological uncertainty. Similar trends to mouth-breathing simulations were observed including increasing aspiration efficiency with decreasing freestream velocity and decreasing aspiration with increasing rotation away from the oncoming wind. These models indicate nasal aspiration in slow moving air occurs only for particles <100 µm.

  16. Effects of air velocity and clothing combination on heating efficiency of an electrically heated vest (EHV): a pilot study.

    PubMed

    Wang, Faming; Gao, Chuansi; Holmér, Ingvar

    2010-09-01

    Cold endangers the heat balance of the human body. Protective clothing is the natural and most common equipment against cold stress. However, clothing for cold protection may be bulky and heavy, affecting human performance and increasing the work load. In such cases, a heated garment with built-in heating elements may be helpful. This pilot study presents a method based on a thermal manikin to investigate the effects of air velocity and clothing combination on the heating efficiency of an electrically heated vest (EHV). An infrared thermal camera was used to detect surface temperature distributions of the EHV on the front and back. Results show that the heating efficiency of the EHV decreases with increasing air velocity. Changes in EHV sequence in the three-layer clothing combination also significantly affect the heating efficiency: it increases with the increasing number of layers on top of the EHV. The highest mean temperature on the inner surface of the EHV was 40.2 degrees C, which indicates that it is safe for the wearers. For the EHV to heat the human body effectively, we suggest that it be worn as a middle layer. Finally, the EHV is especially suitable for occupational groups whose metabolic rate is below 1.9 Mets.

  17. Numerical Simulation of Transient Development of Flame, Temperature and Velocity under Reduced Gravity in a Methane Air Diffusion Flame

    NASA Astrophysics Data System (ADS)

    Bhowal, Arup Jyoti; Mandal, Bijan Kumar

    2017-02-01

    A methane air co flow diffusion flame has been numerically simulated with the help of an in-house developed code at normal gravity, 0.5 G, and 0.0001 G (microgravity) for the study of transient behavior of the flame in terms of flame shape, temperature profile and velocity (streamlines). The study indicates that lower is the gravity level, the higher is the time of early transience. The flame developments during transience are marked by the formation of a secondary flamelet at different heights above the primary flame at all gravity levels. The development of temperature profile at microgravity takes a much longer time to stabilize than the flame development. At normal gravity and 0.5 G gravity level, streamlines, during transience, show intermediate vortices which are finally replaced by recirculation of ambient air from the exit plane. At microgravity, neither any vortex nor any recirculation at any stage is observed. Centerline temperature plots, at all gravity levels during transience, demonstrate a secondary peak at some instants as a consequence of the secondary flamelet formation. The centerline velocity at microgravity decreases gradually during transience, unlike at other two gravity levels where the fall is very sharp and is indicative of negligible buoyancy at microgravity.

  18. Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles. [for combustion studies

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1977-01-01

    A scanning radiometer was used to determine the effect of airstream velocity on the mean drop diameter of water sprays produced by pressure atomizing and air atomizing fuel nozzles used in previous combustion studies. Increasing airstream velocity from 23 to 53.4 meters per second reduced the Sauter mean diameter by approximately 50 percent with both types of fuel nozzles. The use of a sonic cup attached to the tip of an air assist nozzle reduced the Sauter mean diameter by approximately 40 percent. Test conditions included airstream velocities of 23 to 53.4 meters per second at 293 K and atmospheric pressure.

  19. Experimental determination of the velocity and strain rate field in a laminar H2/Air counter-flow diffusion flame via LDA

    NASA Technical Reports Server (NTRS)

    Yeo, S. H.; Dancey, C. L.

    1991-01-01

    Measurements of the axial and radial components of velocity on the air side of stagnation in an axisymmetric H2/Air laminar counter-flow diffusion flame are reported. Results include the two-dimensional velocity field and computed velocity gradients (strain rates) along the stagnation streamline at two 'characteristic' strain rates, below the extinction limit. The measurements generally verify the modeling assumptions appropriate to the model of Kee et al. (1988). The 'traditional' potential flow model is not consistent with the measured results.

  20. Rotations with Rodrigues' Vector

    ERIC Educational Resources Information Center

    Pina, E.

    2011-01-01

    The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears…

  1. On the coefficients of small eddy and surface divergence models for the air-water gas transfer velocity

    NASA Astrophysics Data System (ADS)

    Wang, Binbin; Liao, Qian; Fillingham, Joseph H.; Bootsma, Harvey A.

    2015-03-01

    Recent studies suggested that under low to moderate wind conditions without bubble entraining wave breaking, the air-water gas transfer velocity k+ can be mechanistically parameterized by the near-surface turbulence, following the small eddy model (SEM). Field measurements have supported this model in a variety of environmental forcing systems. Alternatively, surface divergence model (SDM) has also been shown to predict the gas transfer velocity across the air-water interface in laboratory settings. However, the empirically determined model coefficients (α in SEM and c1 in SDM) scattered over a wide range. Here we present the first field measurement of the near-surface turbulence with a novel floating PIV system on Lake Michigan, which allows us to evaluate the SEM and SDM in situ in the natural environment. k+ was derived from the CO2 flux that was measured simultaneously with a floating gas chamber. Measured results indicate that α and c1 are not universal constants. Regression analysis showed that α˜log>(ɛ>) while the near-surface turbulence dissipation rate ɛ is approximately greater than 10-6 m2 s-3 according to data measured for this study as well as from other published results measured in similar environments or in laboratory settings. It also showed that α scales linearly with the turbulent Reynolds number. Similarly, coefficient c1 in the SDM was found to linearly scale with the Reynolds number. These findings suggest that larger eddies are also important parameters, and the dissipation rate in the SEM or the surface divergence β' in the SDM alone may not be adequate to determine k+ completely.

  2. Application of TiC reinforced Fe-based coatings by means of High Velocity Air Fuel Spraying

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Öte, M.; Knoch, M. A.; Liao, X.; Sommer, J.

    2017-03-01

    In the field of hydraulic applications, different development trends can cause problems for coatings currently used as wear and corrosion protection for piston rods. Aqueous hydraulic fluids and rising raw material prices necessitate the search for alternatives to conventional coatings like galvanic hard chrome or High Velocity Oxygen Fuel (HVOF)-sprayed WC/Co coatings. In a previous study, Fe/TiC coatings sprayed by a HVOF-process, were identified to be promising coating systems for wear and corrosion protection in hydraulic systems. In this feasibility study, the novel High Velocity Air Fuel (HVAF)-process, a modification of the HVOF-process, is investigated using the same feedstock material, which means the powder is not optimized for the HVAF-process. The asserted benefits of the HVAF-process are higher particle velocities and lower process temperatures, which can result in a lower porosity and oxidation of the coating. Further benefits of the HVAF process are claimed to be lower process costs and higher deposition rates. In this study, the focus is set on to the applicability of Fe/TiC coatings by HVAF in general. The Fe/TiC HVAF coating could be produced, successfully. The HVAF- and HVOF-coatings, produced with the same powder, were investigated using micro-hardness, porosity, wear and corrosion tests. A similar wear coefficient and micro-hardness for both processes could be achieved. Furthermore the propane/hydrogen proportion of the HVAF process and its influence on the coating thickness and the porosity was investigated.

  3. Correlation of turbulent burning velocities of ethanol-air, measured in a fan-stirred bomb up to 1.2 MPa

    SciTech Connect

    Bradley, D.; Lawes, M.; Mansour, M.S.

    2011-01-15

    The turbulent burning velocity is defined by the mass rate of burning and this also requires that the associated flame surface area should be defined. Previous measurements of the radial distribution of the mean reaction progress variable in turbulent explosion flames provide a basis for definitions of such surface areas for turbulent burning velocities. These inter-relationships. in general, are different from those for burner flames. Burning velocities are presented for a spherical flame surface, at which the mass of unburned gas inside it is equal to the mass of burned gas outside it. These can readily be transformed to burning velocities based on other surfaces. The measurements of the turbulent burning velocities presented are the mean from five different explosions, all under the same conditions. These cover a wide range of equivalence ratios, pressures and rms turbulent velocities for ethanol-air mixtures. Two techniques are employed, one based on measurements of high speed schlieren images, the other on pressure transducer measurements. There is good agreement between turbulent burning velocities measured by the two techniques. All the measurement are generalised in plots of burning velocity normalised by the effective unburned gas rms velocity as a function of the Karlovitz stretch factor for different strain rate Markstein numbers. For a given value of this stretch factor a decrease in Markstein number increases the normalised burning velocity. Comparisons are made with the findings of other workers. (author)

  4. Effects of metabolic rate on thermal responses at different air velocities in -10 degrees C.

    PubMed

    Mäkinen, T T; Gavhed, D; Holmér, I; Rintamäki, H

    2001-04-01

    The effects of exercise intensity on thermoregulatory responses in cold (-10 degrees C) in a 0.2 (still air, NoWi), 1.0 (Wi1), and 5.0 (Wi5) m x s(-1) wind were studied. Eight young and healthy men, preconditioned in thermoneutral (+20 degrees C) environment for 60 min, walked for 60 min on the treadmill at 2.8 km/h with different combinations of wind and exercise intensity. Exercise level was adjusted by changing the inclination of the treadmill between 0 degrees (lower exercise intensity, metabolic rate 124 W x m(-2), LE) and 6 degrees (higher exercise intensity, metabolic rate 195 W x m(-2), HE). Due to exercise increased heat production and circulatory adjustments, the rectal temperature (T(re)), mean skin temperature (Tsk) and mean body temperature (Tb) were significantly higher at the end of HE in comparison to LE in NoWi and Wi1, and T(re) and Tb also in Wi5. Tsk and Tb were significantly decreased by 5.0 m x s(-1) wind in comparison to NoWi and Wi1. The higher exercise intensity was intense enough to diminish peripheral vasoconstriction and consequently the finger skin temperature was significantly higher at the end of HE in comparison to LE in NoWi and Wi1. Mean heat flux from the skin was unaffected by the exercise intensity. At LE oxygen consumption (VO2) was significantly higher in Wi5 than NoWi and Wi1. Heart rate was unaffected by the wind speed. The results suggest that, with studied exercise intensities, produced without changes in walking speed, the metabolic rate is not so important that it should be taken into consideration in the calculation of wind chill index.

  5. Prediction of DC Corona Onset Voltage for Rod-Plane Air Gaps by a Support Vector Machine

    NASA Astrophysics Data System (ADS)

    Jin, Shuo; Ruan, Jiangjun; Du, Zhiye; Zhu, Lin; Shu, Shengwen

    2016-10-01

    This paper proposes a new method to predict the corona onset voltage for a rod-plane air gap, based on the support vector machine (SVM). Because the SVM is not limited by the size, dimension and nonlinearity of the samples, this method can realize accurate prediction with few training data. Only electric field features are chosen as the input; no geometric parameter is included. Therefore, the experiment data of one kind of electrode can be used to predict the corona onset voltages of other electrodes with different sizes. With the experimental data obtained by ozone detection technology, and experimental data provided by the reference, the efficiency of the proposed method is validated. Accurate predicted results with an average relative less than 3% are obtained with only 6 experimental data. supported by National Natural Science Foundation of China (No. 51477120)

  6. A one-dimensional numerical model for predicting pressure and velocity oscillations of a compressed air-pocket in a vertical shaft

    NASA Astrophysics Data System (ADS)

    Choi, Y.; Leon, A.; Apte, S.

    2015-12-01

    The presence of pressurized air pockets in combined sewer systems is argued to produce geyser flows, which is an oscillating jetting of a mixture of gas-liquid flows through vertical shafts. A 1D numerical model is developed for predicting pressure and velocity oscillations of a compressed air-pocket in a vertical shaft which in turn attempts to simulate geyser like flows. The vertical shaft is closed at the bottom and open to ambient pressure at the top. Initially, the lower section of the vertical shaft is filled with compressed air and the upper section with water. The interaction between the pressurized air pocket and the water column in the vertical shaft exhibits an oscillatory motion of the water column that decays over time. The model accounts for steady and unsteady friction to estimate the energy dissipation. The model also includes the falling flow of water around the external perimeter of the pressurized air pocket by assuming that any expansion in the pressurized air pocket would result in the falling volume of water. The acceleration of air-water interface is predicted through a force balance between the pressurized air pocket and the water column combined with the Method of Characteristics that resolves pressure and velocity within the water column. The expansion and compression of the pressurized air pocket is assumed to follow either isothermal process or adiabatic process. Results for both assumptions; isothermal and adiabatic processes, are presented. The performance of the developed 1D numerical model is compared with that of a commercial 3D CFD model. Overall, a good agreement between both models is obtained for pressure and velocity oscillations. The paper will also present a sensitivity analysis of the 3D CFD model.

  7. Study on measurement of the coal powder concentration in pneumatic pipes of a boiler with relationship between air velocity and pressure drop

    SciTech Connect

    Pan, W.; Shen, F.; Lin, W.; Chen, L.; Zhang, D.; Wang, Q.; Ke, J.; Quan, W.

    1999-07-01

    According to the theoretical relationship between air velocity and pressure drop in different solid-air mass flow in vertical pipes with the condition of upward air-solid flowing, the experimental research on measuring the coal powder concentration is directed against the pneumatic pipes of a boiler's combustion system in the energy industry. Through analyzing the experimental results, a mathematical model for measuring the coal powder concentration in pneumatic pipes is obtained. Then, the error analysis is done, and the method of on-line measurement and its function are provided.

  8. Computational simulation of temperature and velocity distribution in human upper respiratory airway during inhalation of hot air.

    PubMed

    Goodarzi-Ardakani, V; Taeibi-Rahni, M; Salimi, M R; Ahmadi, G

    2016-03-01

    The present study provides an accurate simulation of velocity and temperature distributions of inhalation thermal injury in a human upper airway, including vestibule, nasal cavity, paranasal sinuses, nasopharynx, oropharynx, larynx, and upper part of main bronchus. To this end, a series of CT scan images, taken from an adult woman, was used to construct a three dimensional model. The airway walls temperature was adjusted according to existing in vivo temperature measurements. Also, in order to cover all breathing activities, five different breathing flow rates (10, 15, 20, 30, and 40 l/min) and different ambient air temperatures (100, 200, 300, 400, and 500 °C) were studied. Different flow regimes, including laminar, transitional, and turbulence were considered and the simulations were validated using reliable experimental data. The results show that nostrils, vestibule, and nasal cavity are damaged more than other part of airway. Finally, In order to obtain the heat flux through the walls, correlations for Nusselt number for each individual parts of airway (vestibule, main upper airway, nasopharynx etc.,) are proposed.

  9. Laminar burning velocities of lean hydrogen-air mixtures at pressures up to 1.0 MPa

    SciTech Connect

    Bradley, D.; Lawes, M.; Liu, Kexin; Woolley, R.; Verhelst, S.

    2007-04-15

    Values of laminar burning velocity, u{sub l}, and the associated strain rate Markstein number, Ma{sub sr}, of H{sub 2}-air mixtures have been obtained from measurements of flame speeds in a spherical explosion bomb with central ignition. Pressures ranged from 0.1 to 1.0 MPa, with values of equivalence ratio between 0.3 and 1.0. Many of the flames soon became unstable, with an accelerating flame speed, due to Darrieus-Landau and thermodiffusive instabilities. This effect increased with pressure. The flame wrinkling arising from the instabilities enhanced the flame speed. A method is described for allowing for this effect, based on measurements of the flame radii at which the instabilities increased the flame speed. This enabled u{sub l} and Ma{sub sr} to be obtained, devoid of the effects of instabilities. With increasing pressure, the time interval between the end of the ignition spark and the onset of flame instability, during which stable stretched flame propagation occurred, became increasingly small and very high camera speeds were necessary for accurate measurement. Eventually this time interval became so short that first Ma{sub sr} and then u{sub l} could not be measured. Such flame instabilities throw into question the utility of u{sub l} for high pressure, very unstable, flames. The measured values of u{sub l} are compared with those predicted by detailed chemical kinetic models of one-dimensional flames. (author)

  10. Impact of seasonality and air pollutants on carotid-femoral pulse wave velocity and wave reflection in hypertensive patients

    PubMed Central

    Stea, Francesco; Massetti, Luciano; Taddei, Stefano; Ghiadoni, Lorenzo; Modesti, Pietro Amedeo

    2017-01-01

    Objective The effects of seasonality on blood pressure (BP) and cardiovascular (CV) events are well established, while the influence of seasonality and other environmental factors on arterial stiffness and wave reflection has never been analyzed. This study evaluated whether seasonality (daily number of hours of light) and acute variations in outdoor temperature and air pollutants may affect carotid-femoral pulse wave velocity (PWV) and pressure augmentation. Design and method 731 hypertensive patients (30–88 years, 417 treated) were enrolled in a cross-sectional study during a 5-year period. PWV, central BP, Augmentation Index (AIx) and Augmentation Pressure (AP) were measured in a temperature-controlled (22–24°C) room. Data of the local office of the National Climatic Data Observatory were used to estimate meteorological conditions and air pollutants (PM10, O3, CO, N2O) exposure on the same day. Results PWV (mean value 8.5±1.8 m/s) was related to age (r = 0.467, p<0.001), body mass index (r = 0.132, p<0.001), central systolic (r = 0.414, p<0.001) and diastolic BP (r = 0.093, p = 0.013), daylight hours (r = -0.176, p<0.001), mean outdoor temperature (r = -0.082, p = 0.027), O3 (r = -0.135, p<0.001), CO (r = 0.096, p = 0.012), N2O (r = 0.087, p = 0.022). In multiple linear regression analysis, adjusted for confounders, PWV remained independently associated only with daylight hours (β = -0.170; 95% CI: -0.273 to -0.067, p = 0.001). No significant correlation was found between pressure augmentation and daylight hours, mean temperature or air pollutants. The relationship was stronger in untreated patients and women. Furthermore, a positive, independent association between O3 levels and PWV emerged in untreated patients (β: 0.018; p = 0.029; CI: 0.002 to 0.034) and in women (β: 0.027; p = 0.004; CI: 0.009 to 0.045). Conclusions PWV showed a marked seasonality in hypertensive patients. Environmental O3 levels may acutely reduce arterial stiffness in

  11. The effect of wind velocity, air temperature and humidity on NH 3 and SO 2 transfer into bean leaves ( phaseolus vulgaris L.)

    NASA Astrophysics Data System (ADS)

    van Hove, L. W. A.; Vredenberg, W. J.; Adema, E. H.

    The influence of wind velocity, air temperature and vapour pressure deficit of the air (VPD) on NH 3 and SO 2 transfer into bean leaves ( Phaseolus vulgaris L.) was examined using a leaf chamber. The measurements suggested a transition in the properties of the leaf boundary layer at a wind velocity of 0.3-0.4 ms -1 which corresponds to a Recrit value of about 2000. At higher wind velocities the leaf boundary layer resistance ( rb) was 1.5-2 times lower than can be calculated from the theory. Nevertheless, the assessed relationships between rb and wind velocity appeared to be similar to the theoretical derived relationship for rb. The NH 3 flux and in particular the SO 2 flux into the leaf strongly increased at a VPD decline. The increase of the NH 3 flux could be attributed to an increase of the stomatal conductance ( gs). However, the increase of the SO 2 flux could only partly be explained by an increase of gs. An apparent additional uptake was also observed for the NH 3 uptake at a low temperature and VPD. The SO 2 flux was also influenced by air temperature which could be explained by a temperature effect on gs. The results suggest that calculation of the NH 3 and SO 2 flux using data of gs gives a serious understimation of the real flux of these gases into leaves at a low temperature and VPD.

  12. Vector carpets

    SciTech Connect

    Dovey, D.

    1995-03-22

    Previous papers have described a general method for visualizing vector fields that involves drawing many small ``glyphs`` to represent the field. This paper shows how to improve the speed of the algorithm by utilizing hardware support for line drawing and extends the technique from regular to unstructured grids. The new approach can be used to visualize vector fields at arbitrary surfaces within regular and unstructured grids. Applications of the algorithm include interactive visualization of transient electromagnetic fields and visualization of velocity fields in fluid flow problems.

  13. Evaluation of the effect of media velocity on filter efficiency and most penetrating particle size of nuclear grade high-efficiency particulate air filters.

    PubMed

    Alderman, Steven L; Parsons, Michael S; Hogancamp, Kristina U; Waggoner, Charles A

    2008-11-01

    High-efficiency particulate air (HEPA) filters are widely used to control particulate matter emissions from processes that involve management or treatment of radioactive materials. Section FC of the American Society of Mechanical Engineers AG-1 Code on Nuclear Air and Gas Treatment currently restricts media velocity to a maximum of 2.5 cm/sec in any application where this standard is invoked. There is some desire to eliminate or increase this media velocity limit. A concern is that increasing media velocity will result in higher emissions of ultrafine particles; thus, it is unlikely that higher media velocities will be allowed without data to demonstrate the effect of media velocity on removal of ultrafine particles. In this study, the performance of nuclear grade HEPA filters, with respect to filter efficiency and most penetrating particle size, was evaluated as a function of media velocity. Deep-pleat nuclear grade HEPA filters (31 cm x 31 cm x 29 cm) were evaluated at media velocities ranging from 2.0 to 4.5 cm/sec using a potassium chloride aerosol challenge having a particle size distribution centered near the HEPA filter most penetrating particle size. Filters were challenged under two distinct mass loading rate regimes through the use of or exclusion of a 3 microm aerodynamic diameter cut point cyclone. Filter efficiency and most penetrating particle size measurements were made throughout the duration of filter testing. Filter efficiency measured at the onset of aerosol challenge was noted to decrease with increasing media velocity, with values ranging from 99.999 to 99.977%. The filter most penetrating particle size recorded at the onset of testing was noted to decrease slightly as media velocity was increased and was typically in the range of 110-130 nm. Although additional testing is needed, these findings indicate that filters operating at media velocities up to 4.5 cm/sec will meet or exceed current filter efficiency requirements. Additionally

  14. Investigation of the dynamics of spiral galaxies on the base of 3D vector velocity field of their gaseous disks reconstructed from observed line-of-sight velocity field.

    NASA Astrophysics Data System (ADS)

    Fridman, A. M.; Khoruzhii, O. V.; Lyakhovich, V. V.; Silchenko, O. K.; Zasov, A. V.; Afanasiev, V. L.; Dodonov, S. N.

    The method is based on Fourier analysis of observed velocity field. The Fourier harmonics are interpreted in the frame of the consensus on the wave nature of spiral arms. We measured the line-of-sight velocity fields in five spiral galaxies. In grand design galaxies NGC 157, NGC 6181 and NGC 3893 we determined with high accuracy all basic parameters: corotation radius, velocity amplitudes in spiral pattern, the rotation velocity curve with account for motions in spiral arms. The analysis of the flocculent galaxy NGC 2841 helped us to understand the nature of the flocculent spirals. The analysis of grand design galaxy NGC 3631 which is seen face on gave the possibility to explain the nature of vertical motion along the disk rotation axis.

  15. Provide a suitable range to include the thermal creeping effect on slip velocity and temperature jump of an air flow in a nanochannel by lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Karimipour, Arash

    2017-01-01

    The thermal creeping effect on slip velocity of air forced convection through a nanochannel is studied for the first time by using a lattice Boltzmann method. The nanochannel side walls are kept hot while the cold inlet air streams along them. The computations are presented for the wide range of Reynolds number, Knudsen number and Eckert number while slip velocity and temperature jump effects are involved. Moreover appropriate validations are performed versus previous works concerned the micro-nanoflows. The achieved results are shown as the velocity and temperature profiles at different cross sections, streamlines and isotherms and also the values of slip velocity and temperature jump along the nanochannel walls. The ability of the lattice Boltzmann method to simulate the thermal creeping effects on hydrodynamic and thermal domains of flow is shown at this study; so that its effects should be involved at lower values of Eckert number and higher values of Reynolds number especially at entrance region where the most temperature gradient exists.

  16. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  17. Water velocity at water-air interface is not zero: Comment on "Three-dimensional quantification of soil hydraulic properties using X-ray computed tomography and image-based modeling" by Saoirse R. Tracy et al.

    NASA Astrophysics Data System (ADS)

    Zhang, X. X.; Fan, X. Y.; Li, Z. Y.

    2016-07-01

    Tracy et al. (2015, doi: 10.1002/2014WR016020) assumed in their recent paper that water velocity at the water-air interface is zero in their pore-scale simulations of water flow in 3-D soil images acquired using X-ray computed tomography. We comment that such a treatment is physically wrong, and explain that it is the water-velocity gradient in the direction normal to the water-air interface, rather than the water velocity, that should be assumed to be zero at the water-air interface if one needs to decouple the water flow and the air flow. We analyze the potential errors caused by incorrectly taking water velocity at the water-air interface zero based on two simple examples, and conclude that it is not physically sound to make such a presumption because its associated errors are unpredictable.

  18. Investigations of the air flow velocity field structure above the wavy surface under severe wind conditions by particle image velosimetry technique.

    NASA Astrophysics Data System (ADS)

    Troitskaya, Yuliya; Kandaurov, Alexander; Sergeev, Daniil; Ermakova, Olga

    2013-04-01

    Preliminary experiments devoted to measuring characteristics of the air flow above the waved water surface for the wide range of wind speeds were performed with the application of modified Particle Image Velosimetry (PIV) technique. Experiments were carried out at the Wind - wave stratified flume of IAP RAS (length 10 °, cross section of air channel 0.4×0.4 m) for four different axial wind speeds: 8.7, 13.5, 19 and 24 m/s, corresponding to the equivalent 10-m wind speeds 15, 20, 30 40 m/s correspondingly. Intensive wave breaking with forming foam crest and droplets generations was occurred for two last wind conditions. The modified PIV-method based on the use of continuous-wave (CW) laser illumination of the airflow seeded by tiny particles and with highspeed video. Spherical 20 μm polyamide particles with density 1.02 g/sm3 and inertial time 7•10-3 s were used for seeding airflow with special injecting device. Green (532 nm) CW laser with 4 Wt output power was used as a source for light sheet. High speed digital camera Videosprint was used for taking visualized air flow images with the frame rate 2000 Hz s and exposure time 10 ms Combination including iteration Canny method [1] for obtaining curvilinear surface from the images in the laser sheet view and contact measurements of surface elevation by wire wave gauge installed near the border of working area for the surface wave profile was used. Then velocity air flow field was retrieved by PIV images processing with adaptive cross-correlation method on the curvilinear grid following surface wave profile. The mean wind velocity profiles were retrieved by averaging over obtained ensembles of wind velocity field realizations and over a wave period even for the cases of intensive wave breaking and droplets generation. To verify the PIV method additional measurements of mean velocity profiles over were carried out by the contact method using the Pitot tube. In the area of overlap, wind velocity profiles measured by

  19. Tangential Velocity Measurement Using Interferometric MTI Radar

    SciTech Connect

    DOERRY, ARMIN W.; MILESHOSKY, BRIAN P.; BICKEL, DOUGLAS L.

    2002-11-01

    An Interferometric Moving Target Indicator radar can be used to measure the tangential velocity component of a moving target. Multiple baselines, along with the conventional radial velocity measurement, allow estimating the true 3-D velocity vector of a target.

  20. Influence of velocity effects on the shape of N2 (and air) broadened H2O lines revisited with classical molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Ngo, N. H.; Tran, H.; Gamache, R. R.; Bermejo, D.; Domenech, J.-L.

    2012-08-01

    The modeling of the shape of H2O lines perturbed by N2 (and air) using the Keilson-Storer (KS) kernel for collision-induced velocity changes is revisited with classical molecular dynamics simulations (CMDS). The latter have been performed for a large number of molecules starting from intermolecular-potential surfaces. Contrary to the assumption made in a previous study [H. Tran, D. Bermejo, J.-L. Domenech, P. Joubert, R. R. Gamache, and J.-M. Hartmann, J. Quant. Spectrosc. Radiat. Transf. 108, 126 (2007)], 10.1016/j.jqsrt.2007.03.009, the results of these CMDS show that the velocity-orientation and -modulus changes statistically occur at the same time scale. This validates the use of a single memory parameter in the Keilson-Storer kernel to describe both the velocity-orientation and -modulus changes. The CMDS results also show that velocity- and rotational state-changing collisions are statistically partially correlated. A partially correlated speed-dependent Keilson-Storer model has thus been used to describe the line-shape. For this, the velocity changes KS kernel parameters have been directly determined from CMDS, while the speed-dependent broadening and shifting coefficients have been calculated with a semi-classical approach. Comparisons between calculated spectra and measurements of several lines of H2O broadened by N2 (and air) in the ν3 and 2ν1 + ν2 + ν3 bands for a wide range of pressure show very satisfactory agreement. The evolution of non-Voigt effects from Doppler to collisional regimes is also presented and discussed.

  1. Influence of velocity effects on the shape of N2 (and air) broadened H2O lines revisited with classical molecular dynamics simulations.

    PubMed

    Ngo, N H; Tran, H; Gamache, R R; Bermejo, D; Domenech, J-L

    2012-08-14

    The modeling of the shape of H(2)O lines perturbed by N(2) (and air) using the Keilson-Storer (KS) kernel for collision-induced velocity changes is revisited with classical molecular dynamics simulations (CMDS). The latter have been performed for a large number of molecules starting from intermolecular-potential surfaces. Contrary to the assumption made in a previous study [H. Tran, D. Bermejo, J.-L. Domenech, P. Joubert, R. R. Gamache, and J.-M. Hartmann, J. Quant. Spectrosc. Radiat. Transf. 108, 126 (2007)], the results of these CMDS show that the velocity-orientation and -modulus changes statistically occur at the same time scale. This validates the use of a single memory parameter in the Keilson-Storer kernel to describe both the velocity-orientation and -modulus changes. The CMDS results also show that velocity- and rotational state-changing collisions are statistically partially correlated. A partially correlated speed-dependent Keilson-Storer model has thus been used to describe the line-shape. For this, the velocity changes KS kernel parameters have been directly determined from CMDS, while the speed-dependent broadening and shifting coefficients have been calculated with a semi-classical approach. Comparisons between calculated spectra and measurements of several lines of H(2)O broadened by N(2) (and air) in the ν(3) and 2ν(1) + ν(2) + ν(3) bands for a wide range of pressure show very satisfactory agreement. The evolution of non-Voigt effects from Doppler to collisional regimes is also presented and discussed.

  2. Ballistic Range Measurements of Stagnation-Point Heat Transfer in Air and in Carbon Dioxide at Velocities up to 18,000 Feet Per Second

    NASA Technical Reports Server (NTRS)

    Yee, Layton; Bailey, Harry E.; Woodward, Henry T.

    1961-01-01

    A new technique for measuring heat-transfer rates on free-flight models in a ballistic range is described in this report. The accuracy of the heat-transfer rates measured in this way is shown to be comparable with the accuracy obtained in shock-tube measurements. The specific results of the present experiments consist of measurements of the stagnation-point heat-transfer rates experienced by a spherical-nosed model during flight through air and through carbon dioxide at velocities up to 18,000 feet per second. For flight through air these measured heat-transfer rates agree well with both the theoretically predicted rates and the rates measured in shock tubes. the heat-transfer rates agree well with the rates measured in a shock tube. Two methods of estimating the stagnation-point heat-transfer rates in carbon dioxide are compared with the experimental measurements. At each velocity the measured stagnation-point heat-transfer rate in carbon dioxide is about the same as the measured heat-transfer rate in air.

  3. Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms September 10, 1947 to September 15, 1947 at Clinton County Army Air Field, Ohio

    NASA Technical Reports Server (NTRS)

    Funk, Jack

    1948-01-01

    The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from September 10, 1947 to September 15, 1947, are presented.

  4. Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms August 16, 1947 to August 20, 1947 at Clinton County Army Air Field, Ohio

    NASA Technical Reports Server (NTRS)

    Funk, Jack

    1948-01-01

    The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from August 16, 1947 to August 20, 1947 are presented.

  5. Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms August 13, 1947 to August 15, 1947 at Clinton County Army Air Field, Ohio

    NASA Technical Reports Server (NTRS)

    Funk, Jack

    1948-01-01

    The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from August 13, 1947 to August 15, 1947 are presented.

  6. Measuring air-sea gas-exchange velocities in a large-scale annular wind-wave tank

    NASA Astrophysics Data System (ADS)

    Mesarchaki, E.; Kräuter, C.; Krall, K. E.; Bopp, M.; Helleis, F.; Williams, J.; Jähne, B.

    2015-01-01

    In this study we present gas-exchange measurements conducted in a large-scale wind-wave tank. Fourteen chemical species spanning a wide range of solubility (dimensionless solubility, α = 0.4 to 5470) and diffusivity (Schmidt number in water, Scw = 594 to 1194) were examined under various turbulent (u10 = 0.73 to 13.2 m s-1) conditions. Additional experiments were performed under different surfactant modulated (two different concentration levels of Triton X-100) surface states. This paper details the complete methodology, experimental procedure and instrumentation used to derive the total transfer velocity for all examined tracers. The results presented here demonstrate the efficacy of the proposed method, and the derived gas-exchange velocities are shown to be comparable to previous investigations. The gas transfer behaviour is exemplified by contrasting two species at the two solubility extremes, namely nitrous oxide (N2O) and methanol (CH3OH). Interestingly, a strong transfer velocity reduction (up to a factor of 3) was observed for the relatively insoluble N2O under a surfactant covered water surface. In contrast, the surfactant effect for CH3OH, the high solubility tracer, was significantly weaker.

  7. Effects of air velocity on laying hen production from 24 to 27 weeks under simulated evaporatively cooled conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermal conditions play a major role in production efficiency in commercial poultry production. Mitigation of thermal stress can improve productivity, but must be achieved economically. Weather and system design can limit effectiveness of evaporative cooling and increased air movement has been sho...

  8. Error estimations of dry deposition velocities of air pollutants using bulk sea surface temperature under common assumptions

    NASA Astrophysics Data System (ADS)

    Lan, Yung-Yao; Tsuang, Ben-Jei; Keenlyside, Noel; Wang, Shu-Lun; Arthur Chen, Chen-Tung; Wang, Bin-Jye; Liu, Tsun-Hsien

    2010-07-01

    It is well known that skin sea surface temperature (SSST) is different from bulk sea surface temperature (BSST) by a few tenths of a degree Celsius. However, the extent of the error associated with dry deposition (or uptake) estimation by using BSST is not well known. This study tries to conduct such an evaluation using the on-board observation data over the South China Sea in the summers of 2004 and 2006. It was found that when a warm layer occurred, the deposition velocities using BSST were underestimated within the range of 0.8-4.3%, and the absorbed sea surface heat flux was overestimated by 21 W m -2. In contrast, under cool skin only conditions, the deposition velocities using BSST were overestimated within the range of 0.5-2.0%, varying with pollutants and the absorbed sea surface heat flux was underestimated also by 21 W m -2. Scale analysis shows that for a slightly soluble gas (e.g., NO 2, NO and CO), the error in the solubility estimation using BSST is the major source of the error in dry deposition estimation. For a highly soluble gas (e.g., SO 2), the error in the estimation of turbulent heat fluxes and, consequently, aerodynamic resistance and gas-phase film resistance using BSST is the major source of the total error. In contrast, for a medium soluble gas (e.g., O 3 and CO 2) both the errors from the estimations of the solubility and aerodynamic resistance are important. In addition, deposition estimations using various assumptions are discussed. The largest uncertainty is from the parameterizations for chemical enhancement factors. Other important areas of uncertainty include: (1) various parameterizations for gas-transfer velocity; (2) neutral-atmosphere assumption; (3) using BSST as SST, and (4) constant pH value assumption.

  9. Measurement of Off-Body Velocity, Pressure, and Temperature in an Unseeded Supersonic Air Vortex by Stimulated Raman Scattering

    NASA Technical Reports Server (NTRS)

    Herring, Gregory C.

    2008-01-01

    A noninvasive optical method is used to make time-averaged (30 sec) off-body measurements in a supersonic airflow. Seeding of tracer particles is not required. One spatial component of velocity, static pressure, and static temperature are measured with stimulated Raman scattering. The three flow parameters are determined simultaneously from a common sample volume (0.3 by 0.3 by 15 mm) using concurrent measurements of the forward and backward scattered line shapes of a N2 vibrational Raman transition. The capability of this technique is illustrated with laboratory and large-scale wind tunnel testing that demonstrate 5-10% measurement uncertainties. Because the spatial resolution of the present work was improved to 1.5 cm (compared to 20 cm in previous work), it was possible to demonstrate a modest one-dimensional profiling of cross-flow velocity, pressure, and translational temperature through the low-density core of a stream-wise vortex (delta-wing model at Mach 2.8 in NASA Langley's Unitary Plan Wind Tunnel).

  10. A Computational and Experimental Study of Coflow Laminar Methane/Air Diffusion Flames: Effects of Fuel Dilution, Inlet Velocity, and Gravity

    NASA Technical Reports Server (NTRS)

    Cao, S.; Ma, B.; Bennett, B. A. V.; Giassi, D.; Stocker, D. P.; Takahashi, F.; Long, M. B.; Smooke, M. D.

    2014-01-01

    The influences of fuel dilution, inlet velocity, and gravity on the shape and structure of laminar coflow CH4-air diffusion flames were investigated computationally and experimentally. A series of nitrogen-diluted flames measured in the Structure and Liftoff in Combustion Experiment (SLICE) on board the International Space Station was assessed numerically under microgravity (mu g) and normal gravity (1g) conditions with CH4 mole fraction ranging from 0.4 to 1.0 and average inlet velocity ranging from 23 to 90 cm/s. Computationally, the MC-Smooth vorticity-velocity formulation was employed to describe the reactive gaseous mixture, and soot evolution was modeled by sectional aerosol equations. The governing equations and boundary conditions were discretized on a two-dimensional computational domain by finite differences, and the resulting set of fully coupled, strongly nonlinear equations was solved simultaneously at all points using a damped, modified Newton's method. Experimentally, flame shape and soot temperature were determined by flame emission images recorded by a digital color camera. Very good agreement between computation and measurement was obtained, and the conclusions were as follows. (1) Buoyant and nonbuoyant luminous flame lengths are proportional to the mass flow rate of the fuel mixture; computed and measured nonbuoyant flames are noticeably longer than their 1g counterparts; the effect of fuel dilution on flame shape (i.e., flame length and flame radius) is negligible when the flame shape is normalized by the methane flow rate. (2) Buoyancy-induced reduction of the flame radius through radially inward convection near the flame front is demonstrated. (3) Buoyant and nonbuoyant flame structure is mainly controlled by the fuel mass flow rate, and the effects from fuel dilution and inlet velocity are secondary.

  11. Firn air-content of Larsen C Ice Shelf, Antarctic Peninsula, from seismic velocities, borehole surveys and firn modelling

    NASA Astrophysics Data System (ADS)

    Kulessa, Bernd; Brisbourne, Alex; Booth, Adam; Kuipers Munneke, Peter; Bevan, Suzanne; Luckman, Adrian; Hubbard, Bryn; Gourmelen, Noel; Palmer, Steve; Holland, Paul; Ashmore, David; Shepherd, Andrew

    2016-04-01

    The rising surface temperature of Antarctic Peninsula ice shelves is strongly implicated in ice shelf disintegration, by exacerbating the compaction of firn layers. Firn compaction is expected to warm the ice column and, given sufficiently wet and compacted layers, to allow meltwater to penetrate into surface crevasses and thus enhance hydrofracture potential. Integrating seismic refraction surveys with borehole neutron and firn core density logging, we reveal vertical and horizontal changes in firn properties across Larsen C Ice Shelf. Patterns of firn air-content derived from seismic surveys are broadly similar to those estimated previously from airborne radar and satellite data. Specifically, these estimates show greater firn compaction in the north and landward inlets compared to the south, although spatial gradients in seismic-derived air-contents are less pronounced than those previously inferred. Firn thickness is less than 10 m in the extreme northwest of Larsen C, in Cabinet Inlet, yet exceeds 40 m in the southeast, suggesting that the inlet is a focus of firn compaction; indeed, buried layers of massive refrozen ice were observed in 200 MHz GPR data in Cabinet and Whirlwind Inlets during a field campaign in the 2014-15 austral summer. Depth profiles of firn density provide a reasonable fit with those derived from closely-located firn cores and neutron probe data. Our model of firn structure is driven by RACMO and includes a 'bucket'-type hydrological implementation, and simulates the depth-density profiles in the inlets well. Discrepancies between measured and modelled depth-density profiles become progressively greater towards the ice-shelf front. RACMO incorrectly simulates the particular leeward (sea-ice-influenced) microclimate of the shallow boundary layer, leading to excess melt and/or lack of snowfall. The spatial sampling density of our seismic observations will be augmented following a further field campaign in the 2016-17 austral summer

  12. AFWL (Air Force Weapons Laboratory) vectorized EPHULL (Elastic/Plastic HULL) code user manual. Final report, March 1985-May 1986

    SciTech Connect

    Bell, R.L.

    1988-02-01

    This report was prepared as a user manual for implementing the vectorized Elastic/Plastic HULL (EPHULL) Composite HULL code and SAIL code on the AFWL CRAY computer. Major programs required to operate the Composite HULL code and supporting programs and files on the AFWL CRAY are described. The Composite HULL code developed through this work is usable over the range of problems formerly accommodated by either Vector HULL or EPHULL, and is simpler and less time-consuming for new users to learn. The Cylinder In Situ Test (CIST) Equation of State (EOS) in this manual was rewritten from the California Research Arbitrary Lagrangian-Eulerian (CRALE) code for use with a variety of soils.

  13. Experimental study on copper cathode erosion rate and rotational velocity of magnetically driven arcs in a well-type cathode non-transferred plasma torch operating in air

    NASA Astrophysics Data System (ADS)

    Chau, S. W.; Hsu, K. L.; Lin, D. L.; Tzeng, C. C.

    2007-04-01

    The cathode erosion rate, arc root velocity and output power of a well-type cathode (WTC), non-transferred plasma torch operating in air are studied experimentally in this paper. An external solenoid to generate a magnetically driven arc and a circular swirler to produce a vortex flow structure are equipped in the studied torch system, which is designed to reduce the erosion rate at the cathode. A least square technique is applied to correlate the system parameters, i.e. current, axial magnetic field and mass flow rate, with the cathode erosion rate, arc root velocity and system power output. In the studied WTC torch system, the cathode erosion has a major thermal erosion component and a minor component due to the ion-bombardment effect. The cathode erosion increases with the increase of current due to the enhancement in both Joule heating and ion bombardment. The axial magnetic field can significantly reduce the cathode erosion by reducing the thermal loading of cathode materials at the arc root and improving the heat transfer to gas near the cathode. But, the rise in the mass flow rate leads to the deterioration of erosion, since the ion-bombardment effect prevails over the convective cooling at the cathode. The most dominant system parameter to influence the arc root velocity is the axial magnetic field, which is mainly contributed to the magnetic force driving the arc. The growth in current has a negative impact on increasing the arc root velocity, because the friction force acting at the spot due to a severe molten condition becomes the dominant component counteracting the magnetic force. The mass flow rate also suppresses the arc root velocity, as a result of which the arc root moves in the direction against that of the swirled working gas. All system parameters such as current, magnetic field and gas flow rate increase with the increase in the torch output power. The experimental evidences suggest that the axial magnetic field is the most important parameter

  14. Velocity Field Measurements of Human Coughing Using Time Resolved Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Khan, T.; Marr, D. R.; Higuchi, H.; Glauser, M. N.

    2003-11-01

    Quantitative fluid mechanics analysis of human coughing has been carried out using new Time Resolved Particle Image Velocimetry (TRPIV). The study involves measurement of velocity vector time-histories and velocity profiles. It is focused on the average normal human coughing. Some work in the past on cough mechanics has involved measurement of flow rates, tidal volumes and sub-glottis pressure. However, data of unsteady velocity vector field of the exiting highly time-dependent jets is not available. In this study, human cough waveform data are first acquired in vivo using conventional respiratory instrumentation for various volunteers of different gender/age groups. The representative waveform is then reproduced with a coughing/breathing simulator (with or without a manikin) for TRPIV measurements and analysis. The results of this study would be useful not only for designing of indoor air quality and heating, ventilation and air conditioning systems, but also for devising means of protection against infectious diseases.

  15. Gas transfer velocities for quantifying methane, oxygen and other gas fluxes through the air-water interface of wetlands with emergent vegetation

    NASA Astrophysics Data System (ADS)

    Poindexter, C.; Variano, E. A.

    2012-12-01

    Empirical models for the gas transfer velocity, k, in the ocean, lakes and rivers are fairly well established, but there are few data to predict k for wetlands. We have conducted experiments in a simulated emergent marsh in the laboratory to explore the relationship between k, wind shear and thermal convection. Now we identify the implications of these results for gas transfer in actual wetlands by (1) quantifying the range of wind conditions in emergent vegetation canopies and the range of thermal convection intensities in wetland water columns, and (2) describing the non-linear interaction of these two stirring forces over their relevant ranges in wetlands. We measured mean wind speeds and wind speed variance within the shearless region of a Schoenoplectus-Typha marsh canopy in the Sacramento-San Joaquin Delta (Northern California, USA). The mean wind speed within this region, , is significantly smaller than wind above the canopy. Based on our laboratory experiments, for calm or even average wind conditions in this emergent marsh k600 is only on the order 0.1 cm hr-1 (for neutrally or stably stratified water columns). We parameterize unstable thermal stratification and the resulting thermal convection using the heat flux through the air-water interface, q. We analyzed a water temperature record for the Schoenoplectus-Typha marsh to obtain a long-term heat flux record. We used these heat flux data along with short-term heat flux data from other wetlands in the literature to identify the range of the gas transfer velocity associated with thermal convection in wetlands. The typical range of heat fluxes through water columns shaded by closed emergent canopies (-200 W m-2 to +200 W m-2) yields k600 values of 0.5 - 2.5 cm hr-1 according to the model we developed in the laboratory. Thus for calm or average wind conditions, the gas transfer velocity associated with thermal convection is significantly larger than the gas transfer velocity associated with wind

  16. THE M31 VELOCITY VECTOR. III. FUTURE MILKY WAY M31-M33 ORBITAL EVOLUTION, MERGING, AND FATE OF THE SUN

    SciTech Connect

    Van der Marel, Roeland P.; Sohn, Sangmo Tony; Anderson, Jay; Besla, Gurtina; Cox, T. J.

    2012-07-01

    We study the future orbital evolution and merging of the Milky Way (MW)-M31-M33 system, using a combination of collisionless N-body simulations and semi-analytic orbit integrations. Monte Carlo simulations are used to explore the consequences of varying all relevant initial phase-space and mass parameters within their observational uncertainties. The observed M31 transverse velocity from Papers I and II implies that the MW and M31 will merge t = 5.86{sup +1.61}{sub -0.72} Gyr from now. The first pericenter occurs at t = 3.87{sup +0.42}{sub -0.32} Gyr, at a pericenter distance of r = 31.0{sup +38.0}{sub -19.8} kpc. In 41% of Monte Carlo orbits, M31 makes a direct hit with the MW, defined here as a first-pericenter distance less than 25 kpc. For the M31-M33 system, the first-pericenter time and distance are t = 0.85{sup +0.18}{sub -0.13} Gyr and r = 80.8{sup +42.2}{sub -31.7} kpc. By the time M31 gets to its first pericenter with the MW, M33 is close to its second pericenter with M31. For the MW-M33 system, the first-pericenter time and distance are t = 3.70{sup +0.74}{sub -0.46} Gyr and r = 176.0{sup +239.0}{sub -136.9} kpc. The most likely outcome is for the MW and M31 to merge first, with M33 settling onto an orbit around them that may decay toward a merger later. However, there is a 9% probability that M33 makes a direct hit with the MW at its first pericenter, before M31 gets to or collides with the MW. Also, there is a 7% probability that M33 gets ejected from the Local Group, temporarily or permanently. The radial mass profile of the MW-M31 merger remnant is significantly more extended than the original profiles of either the MW or M31, and suggests that the merger remnant will resemble an elliptical galaxy. The Sun will most likely ({approx}85% probability) end up at a larger radius from the center of the MW-M31 merger remnant than its current distance from the MW center, possibly further than 50 kpc ({approx}10% probability). There is a {approx}20

  17. Walk-through survey report: HVLV (high velocity low volume) control technology for aircraft bonded wing and radome maintenance at Air Force Logistics Command, McClellan Air Force Base, Sacramento, California

    SciTech Connect

    Hollett, B.A.

    1983-08-01

    A walk through survey was conducted at the Sacramento Air Logistics Center, McClellan Air Force Base, California, on June 13, 1983, to evaluate the use of High Velocity Low Volume (HVLV) technology in the aircraft-maintenance industry. The HVLV system consisted of 65 ceiling drops in the bonded honeycomb shop where grinding and sanding operations created glass fiber and resin dusts. Preemployment and periodic physical examinations were required. Workers were required to wear disposable coveralls, and disposable dust masks were available. Workers walked through decontamination air jet showers before leaving the area to change clothes. Environmental monitoring revealed no significant dust exposures when the HVLV system was in use. Performance of the exhaust system on the eight-inch-diameter nose cone sanding operation was good, but the three-inch-diameter tools were too large and the shrouds too cumbersome for use on many hand-finishing tasks. The author concludes that the HVLV system is partially successful but requires additional shroud design. Further development of small tool shrouds is recommended.

  18. Noise generated by a flight weight, air flow control valve in a vertical takeoff and landing aircraft thrust vectoring system

    NASA Technical Reports Server (NTRS)

    Huff, Ronald G.

    1989-01-01

    Tests were conducted in the NASA Lewis Research Center's Powered Lift Facility to experimentally evaluate the noise generated by a flight weight, 12 in. butterfly valve installed in a proposed vertical takeoff and landing thrust vectoring system. Fluctuating pressure measurements were made in the circular duct upstream and downstream of the valve. This data report presents the results of these tests. The maximum overall sound pressure level is generated in the duct downstream of the valve and reached a value of 180 dB at a valve pressure ratio of 2.8. At the higher valve pressure ratios the spectra downstream of the valve is broad banded with its maximum at 1000 Hz.

  19. Measurement of Gas and Liquid Velocities in an Air-Water Two-Phase Flow using Cross-Correlation of Signals from a Double Senor Hot-Film Probe

    SciTech Connect

    B. Gurau; P. Vassalo; K. Keller

    2002-02-19

    Local gas and liquid velocities are measured by cross-correlating signals from a double sensor hot-film anemometer probe in pure water flow and air water two-phase flow. The gas phase velocity measured in two-phase flow agrees with velocity data obtained using high-speed video to within +/-5%. A turbulent structure, present in the liquid phase, allows a correlation to be taken, which is consistent with the expected velocity profiles in pure liquid flow. This turbulent structure is also present in the liquid phase of a two-phase flow system. Therefore, a similar technique can be applied to measure the local liquid velocity in a two-phase system, when conditions permit.

  20. Effect of gas-transfer velocity parameterization choice on air-sea CO2 fluxes in the North Atlantic Ocean and the European Arctic

    NASA Astrophysics Data System (ADS)

    Wrobel, Iwona; Piskozub, Jacek

    2016-09-01

    The oceanic sink of carbon dioxide (CO2) is an important part of the global carbon budget. Understanding uncertainties in the calculation of this net flux into the ocean is crucial for climate research. One of the sources of the uncertainty within this calculation is the parameterization chosen for the CO2 gas-transfer velocity. We used a recently developed software toolbox, called the FluxEngine (Shutler et al., 2016), to estimate the monthly air-sea CO2 fluxes for the extratropical North Atlantic Ocean, including the European Arctic, and for the global ocean using several published quadratic and cubic wind speed parameterizations of the gas-transfer velocity. The aim of the study is to constrain the uncertainty caused by the choice of parameterization in the North Atlantic Ocean. This region is a large oceanic sink of CO2, and it is also a region characterized by strong winds, especially in winter but with good in situ data coverage. We show that the uncertainty in the parameterization is smaller in the North Atlantic Ocean and the Arctic than in the global ocean. It is as little as 5 % in the North Atlantic and 4 % in the European Arctic, in comparison to 9 % for the global ocean when restricted to parameterizations with quadratic wind dependence. This uncertainty becomes 46, 44, and 65 %, respectively, when all parameterizations are considered. We suggest that this smaller uncertainty (5 and 4 %) is caused by a combination of higher than global average wind speeds in the North Atlantic (> 7 ms-1) and lack of any seasonal changes in the direction of the flux direction within most of the region. We also compare the impact of using two different in situ pCO2 data sets (Takahashi et al. (2009) and Surface Ocean CO2 Atlas (SOCAT) v1.5 and v2.0, for the flux calculation. The annual fluxes using the two data sets differ by 8 % in the North Atlantic and 19 % in the European Arctic. The seasonal fluxes in the Arctic computed from the two data sets disagree with each

  1. Vector inflation and vortices

    SciTech Connect

    Lewis, C.M. )

    1991-09-15

    A vector field {ital A}{sub {mu}} is coupled to the Einstein equations with a linearly perturbed Friedmann-Robertson-Walker metric, constructed to generate first-order vector perturbations. A working classical chaotic vector inflation is demonstrated and then quantum fluctuations of the field are used to constrain the cosmological perturbations. In particular, the vector momentum flux {ital T}{sub 0{ital i}} is tracked to the epoch where radiation-dominated matter exists. Matching conditions using observational constraints of the cosmic microwave background radiation give rise to a peculiar cosmological velocity of the order of 10{sup {minus}100}{ital c}. Amplification of this number, e.g., by breaking the conformal invariance of the field, could be used to generate cosmic magnetic fields using a dynamo mechanism.

  2. Peculiar cosmological velocities

    SciTech Connect

    Lewis, C.M.

    1990-01-01

    In the first section a gauge-invariant, variations formalism for investigating vector perturbations is set up, suitable for showing that there is no natural way that the usual scalar inflation field could give rise to vorticities. In the last two sections, a vector field A{sub {mu}} is coupled to the Einstein equations with a linearly perturbed Friedmann-Robertson-Walker (FRW) metric, constructed to generate first order vector perturbations. A working classical chaotic vector inflation is demonstrated and then quantum fluctuations of the field are used to constrain the cosmological perturbations. In particular, the vector momentum flux, T{sub 0i}, is tracked to the epoch where a radiation-dominated matter exists. Matching conditions using observational constraints of the cosmic microwave background radiation (CMBR) gives rise to a peculiar cosmological velocity of the order of 10{sup {minus}100}c. Amplification of this number, e.g., by breaking the conformal invariance of the field, could be used to generate cosmic magnetic fields using a dynamo mechanism.

  3. Demonstrating the Direction of Angular Velocity in Circular Motion

    ERIC Educational Resources Information Center

    Demircioglu, Salih; Yurumezoglu, Kemal; Isik, Hakan

    2015-01-01

    Rotational motion is ubiquitous in nature, from astronomical systems to household devices in everyday life to elementary models of atoms. Unlike the tangential velocity vector that represents the instantaneous linear velocity (magnitude and direction), an angular velocity vector is conceptually more challenging for students to grasp. In physics…

  4. Analysis of the air flow generated by an air-assisted sprayer equipped with two axial fans using a 3D sonic anemometer.

    PubMed

    García-Ramos, F Javier; Vidal, Mariano; Boné, Antonio; Malón, Hugo; Aguirre, Javier

    2012-01-01

    The flow of air generated by a new design of air assisted sprayer equipped with two axial fans of reversed rotation was analyzed. For this goal, a 3D sonic anemometer has been used (accuracy: 1.5%; measurement range: 0 to 45 m/s). The study was divided into a static test and a dynamic test. During the static test, the air velocity in the working vicinity of the sprayer was measured considering the following machine configurations: (1) one activated fan regulated at three air flows (machine working as a traditional sprayer); (2) two activated fans regulated at three air flows for each fan. In the static test 72 measurement points were considered. The location of the measurement points was as follow: left and right sides of the sprayer; three sections of measurement (A, B and C); three measurement distances from the shaft of the machine (1.5 m, 2.5 m and 3.5 m); and four measurement heights (1 m, 2 m, 3 m and 4 m). The static test results have shown significant differences in the module and the vertical angle of the air velocity vector in function of the regulations of the sprayer. In the dynamic test, the air velocity was measured at 2.5 m from the axis of the sprayer considering four measurement heights (1 m, 2 m, 3 m and 4 m). In this test, the sprayer regulations were: one or two activated fans; one air flow for each fan; forward speed of 2.8 km/h. The use of one fan (back) or two fans (back and front) produced significant differences on the duration of the presence of wind in the measurement point and on the direction of the air velocity vector. The module of the air velocity vector was not affected by the number of activated fans.

  5. Small Break Air Ingress Experiment

    SciTech Connect

    Chang Oh; Eung Soo Kim

    2011-09-01

    The small break air-ingress experiment, described in this report, is designed to investigate air-ingress phenomena postulated to occur in pipes in a very high temperature gas-cooled reactor (VHTRs). During this experiment, air-ingress rates were measured for various flow and break conditions through small holes drilled into a pipe of the experimental apparatus. The holes were drilled at right angles to the pipe wall such that a direction vector drawn from the pipe centerline to the center of each hole was at right angles with respect to the pipe centerline. Thus the orientation of each hole was obtained by measuring the included angle between the direction vector of each hole with respect to a reference line anchored on the pipe centerline and pointing in the direction of the gravitational force. Using this reference system, the influence of several important parameters on the air ingress flow rate were measured including break orientation, break size, and flow velocity . The approach used to study the influence of these parameters on air ingress is based on measuring the changes in oxygen concentrations at various locations in the helium flow circulation system as a function of time using oxygen sensors (or detectors) to estimate the air-ingress rates through the holes. The test-section is constructed of a stainless steel pipe which had small holes drilled at the desired locations.

  6. In situ evaluation of air-sea CO2 gas transfer velocity in an inner estuary using eddy covariance - with a special focus on the importance of using reliable CO2-fluxes

    NASA Astrophysics Data System (ADS)

    Jørgensen, E. T.; Sørensen, L. L.; Jensen, B.; Sejr, M. K.

    2012-04-01

    The air-sea exchange of CO2 or CO2 flux is driven by the difference in the partial pressure of CO2 in the water and the atmosphere (ΔpCO2), the solubility of CO2 (K0) and the gas transfer velocity (k) (Wanninkhof et al., 2009;Weiss, 1974) . ΔpCO2 and K0 are determined with relatively high precision and it is estimated that the biggest uncertainty when modelling the air-sea flux is the parameterization of k. As an example; the estimated global air-sea flux increases by 70 % when using the parameterization by Wanninkhof and McGillis (1999) instead of Wanninkhof (1992) (Rutgersson et al., 2008). In coastal areas the uncertainty is even higher and only few studies have focused on determining transfer velocity for the coastal waters and even fewer on estuaries (Borges et al., 2004;Rutgersson et al., 2008). The transfer velocity (k600) of CO2 in the inner estuary of Roskilde Fjord, Denmark was investigated using eddy covariance CO2 fluxes (ECM) and directly measured ΔpCO2 during May and June 2010. The data was strictly sorted to heighten the certainty of the results and the outcome was; DS1; using only ECM, and DS2; including the inertial dissipation method (IDM). The inner part of Roskilde Fjord showed to be a very biological active CO2 sink and preliminary results showed that the average k600 was more than 10 times higher than transfer velocities from similar studies of other coastal areas. The much higher transfer velocities were estimated to be caused by the greater fetch and shallower water in Roskilde Fjord, which indicated that turbulence in both air and water influence k600. The wind speed parameterization of k600 using DS1 showed some scatter but when including IDM the r2 of DS2 reached 0.93 with an exponential parameterization, where U10 was based on the Businger-Dyer relationships using friction velocity and atmospheric stability. This indicates that some of the uncertainties coupled with CO2 fluxes calculated by the ECM are removed when including the IDM.

  7. Experimental and numerical analysis of air flow in a dead-end channel

    NASA Astrophysics Data System (ADS)

    Branny, M.; Jaszczur, M.; Wodziak, W.; Szmyd, J.

    2016-09-01

    This study summarises the results of experimental testing and numerical simulations of airflow in a laboratory model of a blind channel aired by a forced ventilation system. The aim of the investigation is qualitative and quantitative verification of computer modelling data. The components of the velocity vector are measured using Particle Image Velocimetry. Two turbulence models, the standard k-ε model and the Reynolds Stress Model, were used in a numerical calculation. A comparison of the magnitude of the velocity vector and the kinetic energy of turbulence obtained by the experimental methods and numerical calculations shows that in qualitative terms, the predicted velocity field correlates well with the measurement data. The mean relative error between the results of the calculations and measurements for the magnitude of the velocity vector and the kinetic energy of turbulence is about 29% for the Reynolds Stress Model and 33% for the standard k-ε model.

  8. Cloning vector

    DOEpatents

    Guilfoyle, R.A.; Smith, L.M.

    1994-12-27

    A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site. 2 figures.

  9. Cloning vector

    DOEpatents

    Guilfoyle, Richard A.; Smith, Lloyd M.

    1994-01-01

    A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site.

  10. Equivalent Vectors

    ERIC Educational Resources Information Center

    Levine, Robert

    2004-01-01

    The cross-product is a mathematical operation that is performed between two 3-dimensional vectors. The result is a vector that is orthogonal or perpendicular to both of them. Learning about this for the first time while taking Calculus-III, the class was taught that if AxB = AxC, it does not necessarily follow that B = C. This seemed baffling. The…

  11. Questions Students Ask: About Terminal Velocity.

    ERIC Educational Resources Information Center

    Meyer, Earl R.; Nelson, Jim

    1984-01-01

    If a ball were given an initial velocity in excess of its terminal velocity, would the upward force of air resistance (a function of velocity) be greater than the downward force of gravity and thus push the ball back upwards? An answer to this question is provided. (JN)

  12. Velocity-vorticity patterns in turbulent flow

    SciTech Connect

    Pelz, R.B.; Yakhot, V.; Orszag, S.A.; Shtilman, L.; Levich, E.

    1985-06-10

    Direct numerical simulation of the Navier-Stokes equations is used for the investigation of local helicity fluctuations in plane Poiseuille (channel) and Taylor-Green vortex flows. It is shown that in regions of high dissipation, the cosine of the angle between velocity and vorticity is evenly distributed; in regions of low dissipation, the velocity and vorticity vectors have a tendency to align. It is also shown that near the central part of the channel, velocity and vorticity vectors have a strong tendency to be aligned, while in the buffer region, all angles are nearly equally probable.

  13. Sodium Velocity Maps on Mercury

    NASA Technical Reports Server (NTRS)

    Potter, A. E.; Killen, R. M.

    2011-01-01

    The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

  14. Demonstrating the Direction of Angular Velocity in Circular Motion

    NASA Astrophysics Data System (ADS)

    Demircioglu, Salih; Yurumezoglu, Kemal; Isik, Hakan

    2015-09-01

    Rotational motion is ubiquitous in nature, from astronomical systems to household devices in everyday life to elementary models of atoms. Unlike the tangential velocity vector that represents the instantaneous linear velocity (magnitude and direction), an angular velocity vector is conceptually more challenging for students to grasp. In physics classrooms, the direction of an angular velocity vector is taught by the right-hand rule, a mnemonic tool intended to aid memory. A setup constructed for instructional purposes may provide students with a more easily understood and concrete method to observe the direction of the angular velocity. This article attempts to demonstrate the angular velocity vector using the observable motion of a screw mounted to a remotely operated toy car.

  15. Particle displacement tracking applied to air flows

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.

    1991-01-01

    Electronic Particle Image Velocimeter (PIV) techniques offer many advantages over conventional photographic PIV methods such as fast turn around times and simplified data reduction. A new all electronic PIV technique was developed which can measure high speed gas velocities. The Particle Displacement Tracking (PDT) technique employs a single cw laser, small seed particles (1 micron), and a single intensified, gated CCD array frame camera to provide a simple and fast method of obtaining two-dimensional velocity vector maps with unambiguous direction determination. Use of a single CCD camera eliminates registration difficulties encountered when multiple cameras are used to obtain velocity magnitude and direction information. An 80386 PC equipped with a large memory buffer frame-grabber board provides all of the data acquisition and data reduction operations. No array processors of other numerical processing hardware are required. Full video resolution (640x480 pixel) is maintained in the acquired images, providing high resolution video frames of the recorded particle images. The time between data acquisition to display of the velocity vector map is less than 40 sec. The new electronic PDT technique is demonstrated on an air nozzle flow with velocities less than 150 m/s.

  16. Notes from 1999 on computational algorithm of the Local Wave-Vector (LWV) model for the dynamical evolution of the second-rank velocity correlation tensor starting from the mean-flow-coupled Navier-Stokes equations

    SciTech Connect

    Zemach, Charles; Kurien, Susan

    2016-11-14

    These notes present an account of the Local Wave Vector (LWV) model of a turbulent flow defined throughout physical space. The previously-developed Local Wave Number (LWN) model is taken as a point of departure. Some general properties of turbulent fields and appropriate notation are given first. The LWV model is presently restricted to incompressible flows and the incompressibility assumption is introduced at an early point in the discussion. The assumption that the turbulence is homogeneous is also introduced early on. This assumption can be relaxed by generalizing the space diffusion terms of LWN, but the present discussion is focused on a modeling of homogeneous turbulence.

  17. Three-dimensional velocity measurements using LDA

    NASA Astrophysics Data System (ADS)

    Buchhave, Preben

    The design requirements for and development of an LDA that measures the three components of the fluid velocity vector are described. The problems encountered in LDA measurements in highly turbulent flows, multivariate response, velocity bias, spatial resolution, temporal resolution, and dynamic range, are discussed. The use of the fringe and/or the reference beam methods to measure the three velocity components, and the use of color, frequency shift, and polarization to separate three velocity projections are examined. Consideration is given to the coordinate transformation, the presentation of three-dimensional LDA data, and the possibility of three-dimensional bias correction. Procedures for conducting three-dimensional LDA measurements are proposed.

  18. Temperature insensitive one-dimensional bending vector sensor based on eccentric-core fiber and air cavity Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Kong, Jing; Zhou, Ai; Yuan, Libo

    2017-04-01

    A temperature insensitive directional bending sensor based on an eccentric-core fiber (ECF) cascaded with an air-cavity Fabry–Perot (F-P) interferometer is presented and demonstrated. The ECF-based air cavity F-P interferometer is fabricated by fuse splicing a piece of hollow-core fiber (HCF) in between an ECF and a multi-mode fiber (MMF). The bending sensitivities of the sensor at the two opposite most sensitive directions are 79.5 pm/m‑1 and ‑81.5 pm/m‑1, respectively. The temperature sensitivity of the proposed structure is as low as 1 pm °C‑1.

  19. Research and Application of an Air Quality Early Warning System Based on a Modified Least Squares Support Vector Machine and a Cloud Model.

    PubMed

    Wang, Jianzhou; Niu, Tong; Wang, Rui

    2017-03-02

    The worsening atmospheric pollution increases the necessity of air quality early warning systems (EWSs). Despite the fact that a massive amount of investigation about EWS in theory and practicality has been conducted by numerous researchers, studies concerning the quantification of uncertain information and comprehensive evaluation are still lacking, which impedes further development in the area. In this paper, firstly a comprehensive warning system is proposed, which consists of two vital indispensable modules, namely effective forecasting and scientific evaluation, respectively. For the forecasting module, a novel hybrid model combining the theory of data preprocessing and numerical optimization is first developed to implement effective forecasting for air pollutant concentration. Especially, in order to further enhance the accuracy and robustness of the warning system, interval forecasting is implemented to quantify the uncertainties generated by forecasts, which can provide significant risk signals by using point forecasting for decision-makers. For the evaluation module, a cloud model, based on probability and fuzzy set theory, is developed to perform comprehensive evaluations of air quality, which can realize the transformation between qualitative concept and quantitative data. To verify the effectiveness and efficiency of the warning system, extensive simulations based on air pollutants data from Dalian in China were effectively implemented, which illustrate that the warning system is not only remarkably high-performance, but also widely applicable.

  20. Research and Application of an Air Quality Early Warning System Based on a Modified Least Squares Support Vector Machine and a Cloud Model

    PubMed Central

    Wang, Jianzhou; Niu, Tong; Wang, Rui

    2017-01-01

    The worsening atmospheric pollution increases the necessity of air quality early warning systems (EWSs). Despite the fact that a massive amount of investigation about EWS in theory and practicality has been conducted by numerous researchers, studies concerning the quantification of uncertain information and comprehensive evaluation are still lacking, which impedes further development in the area. In this paper, firstly a comprehensive warning system is proposed, which consists of two vital indispensable modules, namely effective forecasting and scientific evaluation, respectively. For the forecasting module, a novel hybrid model combining the theory of data preprocessing and numerical optimization is first developed to implement effective forecasting for air pollutant concentration. Especially, in order to further enhance the accuracy and robustness of the warning system, interval forecasting is implemented to quantify the uncertainties generated by forecasts, which can provide significant risk signals by using point forecasting for decision-makers. For the evaluation module, a cloud model, based on probability and fuzzy set theory, is developed to perform comprehensive evaluations of air quality, which can realize the transformation between qualitative concept and quantitative data. To verify the effectiveness and efficiency of the warning system, extensive simulations based on air pollutants data from Dalian in China were effectively implemented, which illustrate that the warning system is not only remarkably high-performance, but also widely applicable. PMID:28257122

  1. An experimental and numerical investigation of velocity in an enclosed residential complex parking area

    NASA Astrophysics Data System (ADS)

    Ashrafi, Khosro; Motlagh, Majid Shafie Pour; Mousavi, Monireh Sadat; Niksokhan, Mohhamad hosein; Vosoughifar, Hamid Reza

    2017-02-01

    The aim of the present research is analysis of velocity vector and magnitude in an enclosed residential complex parking in Tehran. Velocity parameters are key factor and can be helpful in proposing solutions to improve indoor air quality. Since The flow pattern determines that how and where the pollutants propagate. In this research at first, the proportion of vehicular exhaust emissions is estimated and then experimental and numerical analyses are performed. In experimental analysis, a full-scale experiment of parking area has been used; velocity is measured by calibrated measuring devices. Samples were performed in several times. In order to perform numerical calculation, a 3-dimensional model was created by Fluent software that solves flow equations with finite volume method. In this research, the flow condition is assumed to be incompressible and turbulent. Standard k-ɛ scheme was selected as turbulence modeling. In the Computational Fluid Dynamics technique the geometry of parking area is generated in ICEM-CFD software and hexahedral mesh type is used. Velocity vectors and magnitudes in an enclosed residential complex parking in Tehran are estimated. The findings obtained from numerical simulation are in complete accord with experimental results.

  2. Application of support vector machine method for the analysis of absorption spectra of exhaled air of patients with broncho-pulmonary diseases

    NASA Astrophysics Data System (ADS)

    Bukreeva, Ekaterina B.; Bulanova, Anna A.; Kistenev, Yury V.; Kuzmin, Dmitry A.; Tuzikov, Sergei A.; Yumov, Evgeny L.

    2014-11-01

    The results of the joint use of laser photoacoustic spectroscopy and chemometrics methods in gas analysis of exhaled air of patients with respiratory diseases (chronic obstructive pulmonary disease, pneumonia and lung cancer) are presented. The absorption spectra of exhaled breath of all volunteers were measured, the classification methods of the scans of the absorption spectra were applied, the sensitivity/specificity of the classification results were determined. It were obtained a result of nosological in pairs classification for all investigated volunteers, indices of sensitivity and specificity.

  3. Three axis velocity probe system

    DOEpatents

    Fasching, George E.; Smith, Jr., Nelson S.; Utt, Carroll E.

    1992-01-01

    A three-axis velocity probe system for determining three-axis positional velocities of small particles in fluidized bed systems and similar applications. This system has a sensor head containing four closely-spaced sensing electrodes of small wires that have flat ends to establish a two axis plane, e.g. a X-Y plane. Two of the sensing electrodes are positioned along one of the axes and the other two are along the second axis. These four sensing electrodes are surrounded by a guard electrode, and the outer surface is a ground electrode and support member for the sensing head. The electrodes are excited by, for example, sinusoidal voltage having a peak-to-peak voltage of up to 500 volts at a frequency of 2 MHz. Capacitive currents flowing between the four sensing electrodes and the ground electrode are influenced by the presence and position of a particle passing the sensing head. Any changes in these currents due to the particle are amplified and synchronously detected to produce positional signal values that are converted to digital form. Using these digital forms and two values of time permit generation of values of the three components of the particle vector and thus the total velocity vector.

  4. Preflare magnetic and velocity fields

    NASA Technical Reports Server (NTRS)

    Hagyard, M. J.; Gaizauskas, V.; Chapman, G. A.; Deloach, A. C.; Gary, G. A.; Jones, H. P.; Karpen, J. T.; Martres, M.-J.; Porter, J. G.; Schmeider, B.

    1986-01-01

    A characterization is given of the preflare magnetic field, using theoretical models of force free fields together with observed field structure to determine the general morphology. Direct observational evidence for sheared magnetic fields is presented. The role of this magnetic shear in the flare process is considered within the context of a MHD model that describes the buildup of magnetic energy, and the concept of a critical value of shear is explored. The related subject of electric currents in the preflare state is discussed next, with emphasis on new insights provided by direct calculations of the vertical electric current density from vector magnetograph data and on the role of these currents in producing preflare brightenings. Results from investigations concerning velocity fields in flaring active regions, describing observations and analyses of preflare ejecta, sheared velocities, and vortical motions near flaring sites are given. This is followed by a critical review of prevalent concepts concerning the association of flux emergence with flares

  5. Polar versus Cartesian velocity models for maneuvering target tracking with IMM

    NASA Astrophysics Data System (ADS)

    Laneuville, Dann

    This paper compares various model sets in different IMM filters for the maneuvering target tracking problem. The aim is to see whether we can improve the tracking performance of what is certainly the most widely used model set in the literature for the maneuvering target tracking problem: a Nearly Constant Velocity model and a Nearly Coordinated Turn model. Our new challenger set consists of a mixed Cartesian position and polar velocity state vector to describe the uniform motion segments and is augmented with the turn rate to obtain the second model for the maneuvering segments. This paper also gives a general procedure to discretize up to second order any non-linear continuous time model with linear diffusion. Comparative simulations on an air defence scenario with a 2D radar, show that this new approach improves significantly the tracking performance in this case.

  6. Velocity fluctuation analysis via dynamic programming

    SciTech Connect

    Schlossberg, D. J.; Gupta, D. K.; Fonck, R. J.; McKee, G. R.; Shafer, M. W.

    2006-10-15

    A new method of calculating one-dimensional velocity fluctuations from spatially resolved density fluctuation measurements is presented. The algorithm uses vector-matching methods of dynamic programming that match structures, such as turbulent fluctuations, in two data sets. The associated time delay between data sets is estimated by determining an optimal path to transform one vector to another. This time-delay-estimation (TDE) method establishes a new benchmark for velocity analysis by achieving higher sensitivity and frequency response than previously developed methods, such as time-resolved cross correlations and wavelets. TDE has been successfully applied to beam emission spectroscopy measurements of density fluctuations to obtain poloidal flow fluctuations associated with such phenomena as the geodesic acoustic mode. The dynamic programming algorithm should allow extension to high frequency velocity fluctuations associated with underlying electrostatic potential and resulting ExB fluctuations.

  7. High velocity pulsed wire-arc spray

    NASA Technical Reports Server (NTRS)

    Witherspoon, F. Douglas (Inventor); Massey, Dennis W. (Inventor); Kincaid, Russell W. (Inventor)

    1999-01-01

    Wire arc spraying using repetitively pulsed, high temperature gas jets, usually referred to as plasma jets, and generated by capillary discharges, substantially increases the velocity of atomized and entrained molten droplets. The quality of coatings produced is improved by increasing the velocity with which coating particles impact the coated surface. The effectiveness of wire-arc spraying is improved by replacing the usual atomizing air stream with a rapidly pulsed high velocity plasma jet. Pulsed power provides higher coating particle velocities leading to improved coatings. 50 micron aluminum droplets with velocities of 1500 m/s are produced. Pulsed plasma jet spraying provides the means to coat the insides of pipes, tubes, and engine block cylinders with very high velocity droplet impact.

  8. Teaching Universal Gravitation with Vector Games

    ERIC Educational Resources Information Center

    Lowry, Matthew

    2008-01-01

    Like many high school and college physics teachers, I have found playing vector games to be a useful way of illustrating the concepts of inertia, velocity, and acceleration. Like many, I have also had difficulty in trying to get students to understand Newton's law of universal gravitation, specifically the inverse-square law and its application to…

  9. Air entrainment and the dynamics of volcanic jets and plumes

    NASA Astrophysics Data System (ADS)

    Mastin, L. G.; Solovitz, S.

    2008-12-01

    vectors. In our experiments, the jet starts impulsively by developing a mushroom-shaped head, whose base is surrounded by inward- and upward-oriented vectors that indicate concentrated air engulfment. For steady flow, vectors in ambient air near the jet base are directed horizontally inward; but as the horizontal distance from the jet margin increases from ~0.5 to 5 jet diameters, vector orientation becomes steeply upward. The large vertical component of air velocity suggests that the presence of a crater or other topography may affect air entrainment. Also, upward air movement may accentuate the entrainment into the jet of fine debris elutriated from pyroclastic flows on the volcano's flanks.

  10. Investigation of the Penetration on an Air Jet Directed Perpendicularly to an Air Stream

    NASA Technical Reports Server (NTRS)

    Callaghan, Edmund E; Ruggeri, Robert S

    1948-01-01

    An experimental investigation was conducted to determine the penetration of a circular air Jet directed perpendicularly to an air stream as a function of Jet density, Jet velocity, air-stream density, air-stream velocity, Jet diameter, and distance downstream from the Jet. The penetration was determined for nearly constant values of air-stream density at two tunnel velocities, four Jet diameters, four positions downstream of the Jet, and for a large range of Jet velocities and densities. An equation for the penetration was obtained in terms of the Jet diameter, the distance downstream from the jet, and the ratios of Jet and air-stream velocities and densities.

  11. Prediction of flame velocities of hydrocarbon flames

    NASA Technical Reports Server (NTRS)

    Dugger, Gordon L; Simon, Dorothy M

    1954-01-01

    The laminar-flame-velocity data previously reported by the Lewis Laboratory are surveyed with respect to the correspondence between experimental flame velocities and values predicted by semitheoretical and empirical methods. The combustible mixture variables covered are hydrocarbon structure (56 hydrocarbons), equivalence ratio of fuel-air mixture, mole fraction of oxygen in the primary oxygen-nitrogen mixture (0.17 to 0.50), and initial mixture temperature (200 degrees to 615 degrees k). The semitheoretical method of prediction considered are based on three approximate theoretical equations for flame velocity: the Semenov equation, the Tanford-Pease equation, and the Manson equation.

  12. Dry deposition velocities

    SciTech Connect

    Sehmel, G.A.

    1984-03-01

    Dry deposition velocities are very difficult to predict accurately. In this article, reported values of dry deposition velocities are summarized. This summary includes values from the literature on field measurements of gas and particle dry deposition velocities, and the uncertainties inherent in extrapolating field results to predict dry deposition velocities are discussed. A new method is described for predicting dry deposition velocity using a least-squares correlation of surface mass transfer resistances evaluated in wind tunnel experiments. 14 references, 4 figures, 1 table.

  13. Light axial vector mesons

    NASA Astrophysics Data System (ADS)

    Chen, Kan; Pang, Cheng-Qun; Liu, Xiang; Matsuki, Takayuki

    2015-04-01

    Inspired by the abundant experimental observation of axial-vector states, we study whether the observed axial-vector states can be categorized into the conventional axial-vector meson family. In this paper we carry out an analysis based on the mass spectra and two-body Okubo-Zweig-Iizuka-allowed decays. Besides testing the possible axial-vector meson assignments, we also predict abundant information for their decays and the properties of some missing axial-vector mesons, which are valuable for further experimental exploration of the observed and predicted axial-vector mesons.

  14. Vector Along-Track Interferometry for Ocean Current mapping

    NASA Technical Reports Server (NTRS)

    Rodriguez, Ernesto; Imel, David; Madsen, Soren

    1996-01-01

    We examine the feasibility of measuring Along-Track Interferometric (ATI) vector ocean velocities using the azimuth beamwidth of the SAR antenna to obtain angular diversity, at the expense of spatial resolution. A simple model of the measurement is introduced for point targets and moving ocean surfaces to help interpret the velocity measurements.

  15. Orion Exploration Flight Test-1 Contingency Drogue Deploy Velocity Trigger

    NASA Technical Reports Server (NTRS)

    Gay, Robert S.; Stochowiak, Susan; Smith, Kelly

    2013-01-01

    As a backup to the GPS-aided Kalman filter and the Barometric altimeter, an "adjusted" velocity trigger is used during entry to trigger the chain of events that leads to drogue chute deploy for the Orion Multi-Purpose Crew Vehicle (MPCV) Exploration Flight Test-1 (EFT-1). Even though this scenario is multiple failures deep, the Orion Guidance, Navigation, and Control (GN&C) software makes use of a clever technique that was taken from the Mars Science Laboratory (MSL) program, which recently successfully landing the Curiosity rover on Mars. MSL used this technique to jettison the heat shield at the proper time during descent. Originally, Orion use the un-adjusted navigated velocity, but the removal of the Star Tracker to save costs for EFT-1, increased attitude errors which increased inertial propagation errors to the point where the un-adjusted velocity caused altitude dispersions at drogue deploy to be too large. Thus, to reduce dispersions, the velocity vector is projected onto a "reference" vector that represents the nominal "truth" vector at the desired point in the trajectory. Because the navigation errors are largely perpendicular to the truth vector, this projection significantly reduces dispersions in the velocity magnitude. This paper will detail the evolution of this trigger method for the Orion project and cover the various methods tested to determine the reference "truth" vector; and at what point in the trajectory it should be computed.

  16. Vector Doppler: spatial sampling analysis and presentation techniques for real-time systems

    NASA Astrophysics Data System (ADS)

    Capineri, Lorenzo; Scabia, Marco; Masotti, Leonardo F.

    2001-05-01

    The aim of the vector Doppler (VD) technique is the quantitative reconstruction of a velocity field independently of the ultrasonic probe axis to flow angle. In particular vector Doppler is interesting for studying vascular pathologies related to complex blood flow conditions. Clinical applications require a real-time operating mode and the capability to perform Doppler measurements over a defined volume. The combination of these two characteristics produces a real-time vector velocity map. In previous works the authors investigated the theory of pulsed wave (PW) vector Doppler and developed an experimental system capable of producing off-line 3D vector velocity maps. Afterwards, for producing dynamic velocity vector maps, we realized a new 2D vector Doppler system based on a modified commercial echograph. The measurement and presentation of a vector velocity field requires a correct spatial sampling that must satisfy the Shannon criterion. In this work we tackled this problem, establishing a relationship between sampling steps and scanning system characteristics. Another problem posed by the vector Doppler technique is the data representation in real-time that should be easy to interpret for the physician. With this in mine we attempted a multimedia solution that uses both interpolated images and sound to represent the information of the measured vector velocity map. These presentation techniques were experimented for real-time scanning on flow phantoms and preliminary measurements in vivo on a human carotid artery.

  17. Understanding Singular Vectors

    ERIC Educational Resources Information Center

    James, David; Botteron, Cynthia

    2013-01-01

    matrix yields a surprisingly simple, heuristical approximation to its singular vectors. There are correspondingly good approximations to the singular values. Such rules of thumb provide an intuitive interpretation of the singular vectors that helps explain why the SVD is so…

  18. 30 CFR 75.327 - Air courses and trolley haulage systems.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... enough entries or rooms as intake air courses to limit the velocity of air currents in the haulageways to... approves a higher velocity, the velocity of the air current in the trolley haulage entries shall be limited to not more than 250 feet per minute. A higher air velocity may be required to limit the...

  19. 30 CFR 75.327 - Air courses and trolley haulage systems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... enough entries or rooms as intake air courses to limit the velocity of air currents in the haulageways to... approves a higher velocity, the velocity of the air current in the trolley haulage entries shall be limited to not more than 250 feet per minute. A higher air velocity may be required to limit the...

  20. 30 CFR 75.327 - Air courses and trolley haulage systems.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... enough entries or rooms as intake air courses to limit the velocity of air currents in the haulageways to... approves a higher velocity, the velocity of the air current in the trolley haulage entries shall be limited to not more than 250 feet per minute. A higher air velocity may be required to limit the...

  1. 30 CFR 75.327 - Air courses and trolley haulage systems.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... enough entries or rooms as intake air courses to limit the velocity of air currents in the haulageways to... approves a higher velocity, the velocity of the air current in the trolley haulage entries shall be limited to not more than 250 feet per minute. A higher air velocity may be required to limit the...

  2. 30 CFR 75.327 - Air courses and trolley haulage systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... enough entries or rooms as intake air courses to limit the velocity of air currents in the haulageways to... approves a higher velocity, the velocity of the air current in the trolley haulage entries shall be limited to not more than 250 feet per minute. A higher air velocity may be required to limit the...

  3. Rhotrix Vector Spaces

    ERIC Educational Resources Information Center

    Aminu, Abdulhadi

    2010-01-01

    By rhotrix we understand an object that lies in some way between (n x n)-dimensional matrices and (2n - 1) x (2n - 1)-dimensional matrices. Representation of vectors in rhotrices is different from the representation of vectors in matrices. A number of vector spaces in matrices and their properties are known. On the other hand, little seems to be…

  4. Insulated Foamy Viral Vectors.

    PubMed

    Browning, Diana L; Collins, Casey P; Hocum, Jonah D; Leap, David J; Rae, Dustin T; Trobridge, Grant D

    2016-03-01

    Retroviral vector-mediated gene therapy is promising, but genotoxicity has limited its use in the clinic. Genotoxicity is highly dependent on the retroviral vector used, and foamy viral (FV) vectors appear relatively safe. However, internal promoters may still potentially activate nearby genes. We developed insulated FV vectors, using four previously described insulators: a version of the well-studied chicken hypersensitivity site 4 insulator (650cHS4), two synthetic CCCTC-binding factor (CTCF)-based insulators, and an insulator based on the CCAAT box-binding transcription factor/nuclear factor I (7xCTF/NF1). We directly compared these insulators for enhancer-blocking activity, effect on FV vector titer, and fidelity of transfer to both proviral long terminal repeats. The synthetic CTCF-based insulators had the strongest insulating activity, but reduced titers significantly. The 7xCTF/NF1 insulator did not reduce titers but had weak insulating activity. The 650cHS4-insulated FV vector was identified as the overall most promising vector. Uninsulated and 650cHS4-insulated FV vectors were both significantly less genotoxic than gammaretroviral vectors. Integration sites were evaluated in cord blood CD34(+) cells and the 650cHS4-insulated FV vector had fewer hotspots compared with an uninsulated FV vector. These data suggest that insulated FV vectors are promising for hematopoietic stem cell gene therapy.

  5. A comparison of in situ measurements of vector-E and - vector-V x vector-B from Dynamics Explorer 2

    NASA Technical Reports Server (NTRS)

    Hanson, W. B.; Coley, W. R.; Heelis, R. A.; Maynard, N. C.; Aggson, T. L.

    1993-01-01

    Dynamics Explorer-2 provided the first opportunity to make a direct comparison of in situ measurements of the high-latitude convection electric field by two distinctly different techniques. The vector electric field instrument (VEFI) used antennae to measure the intrinsic electric fields and the ion drift meter (IDM) and retarding potential analyzer (RPA) measured the ion drift velocity vector, from which the convection electric field can be deduced. The data from three orbits having large electric fields at high latitude are presented, one at high, one at medium, and one at low altitudes. The general agreement between the two measurements of electric field is very good, with typical differences at high latitudes of the order of a few millivolts per meter, but there are some regions where the particle fluxes are extremely large (e.g., the cusp) and the disagreement is worse, probably because of IDM difficulties. The auroral zone potential patterns derived from the two devices are in excellent agreement for two of the cases, but not in the third, where bad attitude data may be the problem. At low latitudes there are persistent differences in the measurements of a few millivolts per meter, though these differences are quite constant from orbit to orbit. This problem seems to arise from some shortcoming in the VEFI measurments. Overall, however, these measurements confirm the concept of `frozen-in' plasma that drifts with velocity vector-E x vector-B/B(exp 2) within the measurement errors of the two techniques.

  6. Steel Spheres and Skydiver--Terminal Velocity

    ERIC Educational Resources Information Center

    Costa Leme, J.; Moura, C.; Costa, Cintia

    2009-01-01

    This paper describes the use of open source video analysis software in the study of the relationship between the velocity of falling objects and time. We discuss an experiment in which a steel sphere falls in a container filled with two immiscible liquids. The motion is similar to that of a skydiver falling through air.

  7. Fiber Optic Velocity Interferometry

    SciTech Connect

    Neyer, Barry T.

    1988-04-01

    This paper explores the use of a new velocity measurement technique that has several advantages over existing techniques. It uses an optical fiber to carry coherent light to and from a moving target. A Fabry-Perot interferometer, formed by a gradient index lens and the moving target, produces fringes with a frequency proportional to the target velocity. This technique can measure velocities up to 10 km/s, is accurate, portable, and completely noninvasive.

  8. Angular velocity discrimination

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary K.

    1990-01-01

    Three experiments designed to investigate the ability of naive observers to discriminate rotational velocities of two simultaneously viewed objects are described. Rotations are constrained to occur about the x and y axes, resulting in linear two-dimensional image trajectories. The results indicate that observers can discriminate angular velocities with a competence near that for linear velocities. However, perceived angular rate is influenced by structural aspects of the stimuli.

  9. Three-dimensional flow vectors from rf ultrasound signals

    NASA Astrophysics Data System (ADS)

    Tuthill, Theresa A.; Rubin, Jonathan M.; Fowlkes, J. B.

    2002-04-01

    A new ultrasound technique for determining three-dimensional velocity vectors has been devised using radio frequency (RF) data from commercially available scanners. Applied to blood flow, this technique could prove useful for evaluating hemodynamics and detecting stenoses. Three orthogonal velocity vectors are computed from the RF signals of two steered beams from a single array. The in-plane velocities are determined using standard Doppler analysis, while the out-of-plane component is derived from the total velocity as computed from temporal decorrelation and the in-plane components. The technique was tested using contrast agent pumped through a flow tube. A GE Vingmed SystemV scanner with a 10 MHz linear array provided scans at beam steering angles of +/- 20 degree(s). Both Doppler velocities and temporal complex decorrelation were computed for each digitized voxel. Additional studies were done on a blood mimicking fluid and in vivo with a canine femoral artery. Vector plots were constructed to show flow for various transducer angles. Angle estimates were within 20 degree(s), and the mean error for the velocity amplitude was less than 15%. The in vivo results provided velocity estimates consistent with the literature. The proposed method, unlike current Doppler velocity measurement techniques, provides quantitative velocity information independent of transducer orientation.

  10. Mapping surface currents from HF radar radial velocity measurements using optimal interpolation

    NASA Astrophysics Data System (ADS)

    Kim, Sung Yong; Terrill, Eric J.; Cornuelle, Bruce D.

    2008-10-01

    An optimal interpolation (OI) method to compute surface vector current fields from radial velocity measurements derived from high-frequency (HF) radars is presented. The method assumes a smooth spatial covariance relationship between neighboring vector currents, in contrast to the more commonly used un-weighted least-squares fitting (UWLS) method, which assumes a constant vector velocity within a defined search radius. This OI method can directly compute any quantities linearly related to the radial velocities, such as vector currents and dynamic quantities (divergence and vorticity) as well as the uncertainties of those respective fields. The OI method is found to be more stable than the UWLS method and reduces spurious vector solutions near the baselines between HF radar installations. The OI method produces a covariance of the uncertainty of the estimated vector current fields. Three nondimensional uncertainty indices are introduced to characterize the uncertainty of the vector current at a point, representing an ellipse with directional characteristics. The vector current estimation using the OI method eliminates the need for multiple mapping steps and optimally fills intermittent coverage gaps. The effects of angular interpolation of radial velocities, a commonly used step in the preprocessing of radial velocity data prior to vector current computation in the UWLS method, are presented.

  11. Covariantized vector Galileons

    NASA Astrophysics Data System (ADS)

    Hull, Matthew; Koyama, Kazuya; Tasinato, Gianmassimo

    2016-03-01

    Vector Galileons are ghost-free systems containing higher derivative interactions of vector fields. They break the vector gauge symmetry, and the dynamics of the longitudinal vector polarizations acquire a Galileon symmetry in an appropriate decoupling limit in Minkowski space. Using an Arnowitt-Deser-Misner approach, we carefully reconsider the coupling with gravity of vector Galileons, with the aim of studying the necessary conditions to avoid the propagation of ghosts. We develop arguments that put on a more solid footing the results previously obtained in the literature. Moreover, working in analogy with the scalar counterpart, we find indications for the existence of a "beyond Horndeski" theory involving vector degrees of freedom that avoids the propagation of ghosts thanks to secondary constraints. In addition, we analyze a Higgs mechanism for generating vector Galileons through spontaneous symmetry breaking, and we present its consistent covariantization.

  12. Low Cost Air Combat Training System

    NASA Astrophysics Data System (ADS)

    Flynn, Earl

    1987-10-01

    Air combat training has evolved into a highly sophisticated and expensive process. To effectively train fighter pilots in air-to-air combat, interaction between pilots is essential. This interaction can be accomplished using multiple low cost laser image projections of friend and/or foe aircraft controlled by pilots in a multiple dome configuration. A Laser Target Projector (LTP) produces a calligraphically written aircraft model comprised of up to 200 vectors which are updated at a 60 Hz rate. The resulting wire frame image imparts both position, velocity, distance and altitude information to the pilots. Using a laser light source guarantees high luminance levels and provides large depths of field. This large depth of field allows for unique packaging arrangements and cost saving attributes. The LTP has total dome coverage via a computer-controlled, servo-driven, gimb-alled two-axis assembly that projects the wire frame aircraft image onto the dome surface. To unburden the host computer, all dome-to-dome communication, real world-to-dome coordinate transformations and all geometry corrections are done by a special purpose high-speed computer called a Dome Master. Each dome has one Dome Master that can drive up to six LTP's. This paper will deal with the technical aspects of the design and development of the LTP and Dome Master as a low cost air combat training system.

  13. Experimental characterization of a vector Doppler system based on a clinical ultrasound scanner.

    PubMed

    Eranki, Avinash; Sikdar, Siddhartha

    2009-01-01

    We have developed a vector Doppler system using a clinical ultrasound scanner with a research interface. In this system, vector Doppler estimation is performed by electronically dividing a linear array transducer into a transmit sub-aperture and two receive sub-apertures. The receive beams are electronically steered, and two velocity components are estimated from echoes received from the beam overlap region. The velocity vector is reconstructed from these two estimates. The goal of this study was to characterize this vector Doppler system in vitro using a string phantom with a pulsatile velocity waveform. We studied the effect of four parameters on the estimation error: beam steering angle, angle of the velocity vector, depth of the scatterer relative to the beam overlap region and the transmit focus depth. Our results show that changing these parameters have minimal effect on the velocity and angle estimates, and robust velocity vector estimates can be obtained under a variety of conditions. The mean velocity error was less than 0.06 x pulse repetition frequency. The velocity estimates are sensitive to the Doppler estimation method. Our results indicate that vector Doppler using a linear array transducer is feasible for a wide range of imaging parameters. Such a system would facilitate the investigation of complex blood flow and tissue motion in human subjects.

  14. 30 CFR 57.22211 - Air flow (I-A mines).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Methane in Metal and Nonmetal Mines Ventilation § 57.22211 Air flow (I-A mines). The average air velocity... openings nearest the face, shall be at least 40 feet per minute. The velocity of air ventilating each...

  15. 30 CFR 57.22211 - Air flow (I-A mines).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Methane in Metal and Nonmetal Mines Ventilation § 57.22211 Air flow (I-A mines). The average air velocity... openings nearest the face, shall be at least 40 feet per minute. The velocity of air ventilating each...

  16. 30 CFR 57.22211 - Air flow (I-A mines).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Methane in Metal and Nonmetal Mines Ventilation § 57.22211 Air flow (I-A mines). The average air velocity... openings nearest the face, shall be at least 40 feet per minute. The velocity of air ventilating each...

  17. 30 CFR 57.22211 - Air flow (I-A mines).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Methane in Metal and Nonmetal Mines Ventilation § 57.22211 Air flow (I-A mines). The average air velocity... openings nearest the face, shall be at least 40 feet per minute. The velocity of air ventilating each...

  18. 30 CFR 57.22211 - Air flow (I-A mines).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Methane in Metal and Nonmetal Mines Ventilation § 57.22211 Air flow (I-A mines). The average air velocity... openings nearest the face, shall be at least 40 feet per minute. The velocity of air ventilating each...

  19. A Tool and a Method for Obtaining Hydrologic Flow Velocity Measurements in Geothermal Reservoirs

    SciTech Connect

    Carrigan, C.R.; Dunn, J.C.; Hardee, H.C.

    1986-01-21

    Downhole instruments based on a thermal perturbation principle are being developed to measure heat flow in permeable formations where convective transport of heat is important. To make heat flow measurements in these regions, the ground water velocity vector must be determined. A downhole probe has been designed to measure the local ground water velocity vector. The probe is a cylindrical heat source operated at a constant heat flux. In a convecting environment, surface temperatures on the probe are perturbed from those values of a purely conductive environment. With the aid of analytical and numerical models, these temperature differences can be related to the local velocity vector.

  20. Tool and a method for obtaining hydrologic flow velocity measurements in geothermal reservoirs

    SciTech Connect

    Carrigan, C.R.; Dunn, J.C.; Hardee, H.C.

    1986-01-01

    Downhole instruments based on a thermal perturbation principle are being developed to measure heat flow in permeable formations where convective transport of heat is important. To make heat flow measurements in these regions, the ground water velocity vector must be determined. A downhole probe has been designed to measure the local ground water velocity vector. The probe is a cylindrical heat source operated at a constant heat flux. In a convecting environment, surface temperatures on the probe are perturbed from those values of a purely conductive environment. With the aid of analytical and numerical models, these temperature differences can be related to the local velocity vector. 4 refs., 2 figs.

  1. Inferring Lower Boundary Driving Conditions Using Vector Magnetic Field Observations

    NASA Technical Reports Server (NTRS)

    Schuck, Peter W.; Linton, Mark; Leake, James; MacNeice, Peter; Allred, Joel

    2012-01-01

    Low-beta coronal MHD simulations of realistic CME events require the detailed specification of the magnetic fields, velocities, densities, temperatures, etc., in the low corona. Presently, the most accurate estimates of solar vector magnetic fields are made in the high-beta photosphere. Several techniques have been developed that provide accurate estimates of the associated photospheric plasma velocities such as the Differential Affine Velocity Estimator for Vector Magnetograms and the Poloidal/Toroidal Decomposition. Nominally, these velocities are consistent with the evolution of the radial magnetic field. To evolve the tangential magnetic field radial gradients must be specified. In addition to estimating the photospheric vector magnetic and velocity fields, a further challenge involves incorporating these fields into an MHD simulation. The simulation boundary must be driven, consistent with the numerical boundary equations, with the goal of accurately reproducing the observed magnetic fields and estimated velocities at some height within the simulation. Even if this goal is achieved, many unanswered questions remain. How can the photospheric magnetic fields and velocities be propagated to the low corona through the transition region? At what cadence must we observe the photosphere to realistically simulate the corona? How do we model the magnetic fields and plasma velocities in the quiet Sun? How sensitive are the solutions to other unknowns that must be specified, such as the global solar magnetic field, and the photospheric temperature and density?

  2. Tracking Vector Magnetograms with the Helioseismic and Magnetic Imager

    NASA Astrophysics Data System (ADS)

    Schuck, Peter W.

    2012-05-01

    We present analysis of SDO/HMI magnetograms using the Differential Affine Velocity Estimator for Vector Magnetograms with Doppler Velocities (DAVE4VMwDV) which is an extension of the local Cartesian DAVE4VM velocity estimation algorithm. The new DAVE4VMWDV inversion algorithm has several advantages specifically tailored for utilizing the SDO/HMI vector magnetograms. First, the inversion incorporates the spherical geometry of the Sun and provides direct estimates of spherical components of the plasma velocity and uncertainties. Second, the inversions may be performed in the image plane with the Jacobian computed from the gradient of the Stonyhurst coordinates at each pixel --- the data does not have to be distorted into a Mercator or other projection for analysis. Third, the profiles of plasma velocity within the local aperture are expressed as discrete Legendre polynomials of arbitrary order permitting larger apertures while preserving accuracy whereas DAVE4VM was limited to an affine (linear) velocity profile within the aperture. Fourth, the contribution of individual pixels may be weighted statistically and/or individual pixels may be eliminated from the analysis because of poor inversions and/or disambiguations. Fifth, the line-of-sight Doppler velocity may be used as a weighted constraint to improve the estimate regardless of the location of the pixel on the Sun. These advantages are unique to DAVE4VMWDV and have not been implemented in any other velocity inversion algorithms. We discuss the application of DAVE4VMWDV to simulation data and SDO/HMI vector magnetograms.

  3. The role of the harmonic vector average in motion integration.

    PubMed

    Johnston, Alan; Scarfe, Peter

    2013-01-01

    The local speeds of object contours vary systematically with the cosine of the angle between the normal component of the local velocity and the global object motion direction. An array of Gabor elements whose speed changes with local spatial orientation in accordance with this pattern can appear to move as a single surface. The apparent direction of motion of plaids and Gabor arrays has variously been proposed to result from feature tracking, vector addition and vector averaging in addition to the geometrically correct global velocity as indicated by the intersection of constraints (IOC) solution. Here a new combination rule, the harmonic vector average (HVA), is introduced, as well as a new algorithm for computing the IOC solution. The vector sum can be discounted as an integration strategy as it increases with the number of elements. The vector average over local vectors that vary in direction always provides an underestimate of the true global speed. The HVA, however, provides the correct global speed and direction for an unbiased sample of local velocities with respect to the global motion direction, as is the case for a simple closed contour. The HVA over biased samples provides an aggregate velocity estimate that can still be combined through an IOC computation to give an accurate estimate of the global velocity, which is not true of the vector average. Psychophysical results for type II Gabor arrays show perceived direction and speed falls close to the IOC direction for Gabor arrays having a wide range of orientations but the IOC prediction fails as the mean orientation shifts away from the global motion direction and the orientation range narrows. In this case perceived velocity generally defaults to the HVA.

  4. Molecular neurosurgery: vectors and vector delivery strategies.

    PubMed

    White, Edward

    2012-12-01

    Molecular neurosurgery involves the use of vector-mediated gene therapy and gene knockdown to manipulate in vivo gene expression for the treatment of neurological diseases. These techniques have the potential to revolutionise the practice of neurosurgery. However, significant challenges remain to be overcome before these techniques enter routine clinical practice. These challenges have been the subject of intensive research in recent years and include the development of strategies to facilitate effective vector delivery to the brain and the development of both viral and non-viral vectors that are capable of efficient cell transduction without excessive toxicity. This review provides an update on the practice of molecular neurosurgery with particular focus on the practical neurosurgical aspects of vector delivery to the brain. In addition, an introduction to the key vectors employed in clinical trials and a brief overview of previous gene therapy clinical trials is provided. Finally, key areas for future research aimed at increasing the likelihood of the successful translation of gene therapy into clinical trials are highlighted.

  5. Climate change velocity underestimates climate change exposure in mountainous regions

    PubMed Central

    Dobrowski, Solomon Z.; Parks, Sean A.

    2016-01-01

    Climate change velocity is a vector depiction of the rate of climate displacement used for assessing climate change impacts. Interpreting velocity requires an assumption that climate trajectory length is proportional to climate change exposure; longer paths suggest greater exposure. However, distance is an imperfect measure of exposure because it does not quantify the extent to which trajectories traverse areas of dissimilar climate. Here we calculate velocity and minimum cumulative exposure (MCE) in degrees Celsius along climate trajectories for North America. We find that velocity is weakly related to MCE; each metric identifies contrasting areas of vulnerability to climate change. Notably, velocity underestimates exposure in mountainous regions where climate trajectories traverse dissimilar climates, resulting in high MCE. In contrast, in flat regions velocity is high where MCE is low, as these areas have negligible climatic resistance to movement. Our results suggest that mountainous regions are more climatically isolated than previously reported. PMID:27476545

  6. Climate change velocity underestimates climate change exposure in mountainous regions

    NASA Astrophysics Data System (ADS)

    Dobrowski, Solomon Z.; Parks, Sean A.

    2016-08-01

    Climate change velocity is a vector depiction of the rate of climate displacement used for assessing climate change impacts. Interpreting velocity requires an assumption that climate trajectory length is proportional to climate change exposure; longer paths suggest greater exposure. However, distance is an imperfect measure of exposure because it does not quantify the extent to which trajectories traverse areas of dissimilar climate. Here we calculate velocity and minimum cumulative exposure (MCE) in degrees Celsius along climate trajectories for North America. We find that velocity is weakly related to MCE; each metric identifies contrasting areas of vulnerability to climate change. Notably, velocity underestimates exposure in mountainous regions where climate trajectories traverse dissimilar climates, resulting in high MCE. In contrast, in flat regions velocity is high where MCE is low, as these areas have negligible climatic resistance to movement. Our results suggest that mountainous regions are more climatically isolated than previously reported.

  7. Solving the Christoffel equation: Phase and group velocities

    NASA Astrophysics Data System (ADS)

    Jaeken, Jan W.; Cottenier, Stefaan

    2016-10-01

    We provide christoffel, a Python tool for calculating direction-dependent phase velocities, polarization vectors, group velocities, power flow angles and enhancement factors based on the stiffness tensor of a solid. It is built in a modular way to allow for efficient and flexible calculations, and the freedom to select and combine results as desired. All derivatives are calculated analytically, which circumvents possible numerical sampling problems. GNUPlot scripts are provided for convenient visualization.

  8. Visualizing 3D velocity fields near contour surfaces

    SciTech Connect

    Max, N.; Crawfis, R.; Grant, C.

    1994-03-01

    Vector field rendering is difficult in 3D because the vector icons overlap and hide each other. We propose four different techniques for visualizing vector fields only near surfaces. The first uses motion blurred particles in a thickened region around the surface. The second uses a voxel grid to contain integral curves of the vector field. The third uses many antialiased lines through the surface, and the fourth uses hairs sprouting from the surface and then bending in the direction of the vector field. All the methods use the graphite pipeline, allowing real time rotation and interaction, and the first two methods can animate the texture to move in the flow determined by the velocity field.

  9. Vehicle Based Vector Sensor

    DTIC Science & Technology

    2015-09-28

    300001 1 of 16 VEHICLE-BASED VECTOR SENSOR STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and...unmanned underwater vehicle that can function as an acoustic vector sensor . (2) Description of the Prior Art [0004] It is known that a propagating...mechanics. An acoustic vector sensor measures the particle motion via an accelerometer and combines Attorney Docket No. 300001 2 of 16 the

  10. Velocity profile development for a poultry facility acid scrubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determination of the air velocity profile for 12 experimental configurations (ECs) of an acid scrubber was carried out using an equal area traverse method with a vane axial anemometer. Four velocity profile plots were created for each configuration to determine the four optimal ECs. ECs were selecte...

  11. A MAGNETIC CALIBRATION OF PHOTOSPHERIC DOPPLER VELOCITIES

    SciTech Connect

    Welsch, Brian T.; Fisher, George H.; Sun, Xudong

    2013-03-10

    The zero point of measured photospheric Doppler shifts is uncertain for at least two reasons: instrumental variations (from, e.g., thermal drifts); and the convective blueshift, a known correlation between intensity and upflows. Accurate knowledge of the zero point is, however, useful for (1) improving estimates of the Poynting flux of magnetic energy across the photosphere, and (2) constraining processes underlying flux cancellation, the mutual apparent loss of magnetic flux in closely spaced, opposite-polarity magnetogram features. We present a method to absolutely calibrate line-of-sight (LOS) velocities in solar active regions (ARs) near disk center using three successive vector magnetograms and one Dopplergram coincident with the central magnetogram. It exploits the fact that Doppler shifts measured along polarity inversion lines (PILs) of the LOS magnetic field determine one component of the velocity perpendicular to the magnetic field, and optimizes consistency between changes in LOS flux near PILs and the transport of transverse magnetic flux by LOS velocities, assuming that ideal electric fields govern the magnetic evolution. Previous calibrations fitted the center-to-limb variation of Doppler velocities, but this approach cannot, by itself, account for residual convective shifts at the limb. We apply our method to vector magnetograms of AR 11158, observed by the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory, and find clear evidence of offsets in the Doppler zero point in the range of 50-550 m s{sup -1}. In addition, we note that a simpler calibration can be determined from an LOS magnetogram and Dopplergram pair from the median Doppler velocity among all near-disk-center PIL pixels. We briefly discuss shortcomings in our initial implementation, and suggest ways to address these. In addition, as a step in our data reduction, we discuss the use of temporal continuity in the transverse magnetic field direction to correct apparently

  12. High Velocity Gas Gun

    NASA Technical Reports Server (NTRS)

    1988-01-01

    A video tape related to orbital debris research is presented. The video tape covers the process of loading a High Velocity Gas Gun and firing it into a mounted metal plate. The process is then repeated in slow motion.

  13. Velocity of Sound

    ERIC Educational Resources Information Center

    Gillespie, A.

    1975-01-01

    Describes a method for the determination of the velocity of sound using a dual oscilloscope on which is displayed the sinusoidal input into a loudspeaker and the signal picked up by a microphone. (GS)

  14. SAMPEX science pointing with velocity avoidance

    NASA Astrophysics Data System (ADS)

    Frakes, Joseph P.; Henretty, Debra A.; Flatley, Thomas W.; Markley, F. L.; San, Josephine K.; Lightsey, E. G.

    The Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) science pointing mode is presented with the additional constraint of velocity avoidance. This constraint has been added in light of the orbital debris and micrometeoroid fluxes that have been revealed by the Long Duration Exposure Facility (LDEF) recovered in January 1990. These fluxes are 50-100 times higher than the flux tables that were used in the September 1988 proposal to NASA for the SAMPEX mission. The SAMPEX Heavey Ion Large Telescope (HILT) sensor includes a flow-through isobutane proportional counter that is susceptible to penetration by orbital debris and micrometeoroids. Thus, keeping the HILT sensor pointed away from the velocity vector, the direction of maximum flux, will compensate for the higher than expected fluxes. Using an orbital debris model and a micrometeoroid model developed at the Johnson Space Center (JSC), and a SAMPEX dynamic simulator developed by the Guidance and Control Branch at the Goddard Space Flight Center (GSFC), an 'optimal' minimum ram angle (the angle between the HILT boresight and the velocity vector) of 90 degrees has been determined. It is optimal in the sense of minimizing the science pointing performance degradation while providing approximately an 89 percent chance of survival for the HILT sensor over a three year period.

  15. Improved high volume air sampler

    NASA Technical Reports Server (NTRS)

    King, R. B.

    1974-01-01

    Sampler permits size separations of particles by directing sampled air through cross-sectional area sufficiently large that air velocity is reduced to point where particles or larger size will settle out. Sampler conducts air downward and through slots around periphery of unit into relatively open interior of house.

  16. Microcavity confinement based on an anomalous zero group-velocity waveguide mode

    NASA Astrophysics Data System (ADS)

    Ibanescu, Mihai; Johnson, Steven G.; Roundy, David; Fink, Yoel; Joannopoulos, J. D.

    2005-03-01

    We propose and demonstrate a mechanism for small-modal-volume high-Q cavities based on an anomalous uniform waveguide mode that has zero group velocity at a nonzero wave vector. In a short piece of a uniform waveguide with a specially designed cross section, light is confined longitudinally by small group-velocity propagation and transversely by a reflective cladding. The quality factor Q is greatly enhanced by the small group velocity for a set of cavity lengths that are separated by approximately pi/k_0, where k_0 is the longitudinal wave vector for which the group velocity is zero.

  17. Tracking Vector Magnetograms from the Solar Dynamics Observatory

    NASA Astrophysics Data System (ADS)

    Schuck, P. W.; Sun, X.; Muglach, K.; Hoeksema, J. T.

    2010-12-01

    The differential affine velocity estimator for vector magnetograms (DAVE4VM) has been developed for estimating photospheric velocities. The accuracy of this technique has been demonstrated on synthetic magnetograms from MHD simulations. The algorithm was initially formulated in Cartesian coordinates. Thus, for best results, solar vector magnetograms must be transformed from the image plane into a Mercator map or some other Cartesian-like projection before applyng DAVE4VM. Recently, DAVE4VM has been modified to incorporate directly the projected spherical geometry of Helioprojective-Cartesian coordinates, thus permitting direct application of the method to image plane vector magnetograms. We will discuss the new algorithm and tests of the modified method and present first results of DAVE4VM applied to Solar Dynamics Observatory vector magnetograms.

  18. Velocity Based Modulus Calculations

    NASA Astrophysics Data System (ADS)

    Dickson, W. C.

    2007-12-01

    A new set of equations are derived for the modulus of elasticity E and the bulk modulus K which are dependent only upon the seismic wave propagation velocities Vp, Vs and the density ρ. The three elastic moduli, E (Young's modulus), the shear modulus μ (Lamé's second parameter) and the bulk modulus K are found to be simple functions of the density and wave propagation velocities within the material. The shear and elastic moduli are found to equal the density of the material multiplied by the square of their respective wave propagation-velocities. The bulk modulus may be calculated from the elastic modulus using Poisson's ratio. These equations and resultant values are consistent with published literature and values in both magnitude and dimension (N/m2) and are applicable to the solid, liquid and gaseous phases. A 3D modulus of elasticity model for the Parkfield segment of the San Andreas Fault is presented using data from the wavespeed model of Thurber et al. [2006]. A sharp modulus gradient is observed across the fault at seismic depths, confirming that "variation in material properties play a key role in fault segmentation and deformation style" [Eberhart-Phillips et al., 1993] [EPM93]. The three elastic moduli E, μ and K may now be calculated directly from seismic pressure and shear wave propagation velocities. These velocities may be determined using conventional seismic reflection, refraction or transmission data and techniques. These velocities may be used in turn to estimate the density. This allows velocity based modulus calculations to be used as a tool for geophysical analysis, modeling, engineering and prospecting.

  19. Viral Vector Production: Adenovirus.

    PubMed

    Kim, Julius W; Morshed, Ramin A; Kane, J Robert; Auffinger, Brenda; Qiao, Jian; Lesniak, Maciej S

    2016-01-01

    Adenoviral vectors have proven to be valuable resources in the development of novel therapies aimed at targeting pathological conditions of the central nervous system, including Alzheimer's disease and neoplastic brain lesions. Not only can some genetically engineered adenoviral vectors achieve remarkably efficient and specific gene delivery to target cells, but they also may act as anticancer agents by selectively replicating within cancer cells.Due to the great interest in using adenoviral vectors for various purposes, the need for a comprehensive protocol for viral vector production is especially apparent. Here, we describe the process of generating an adenoviral vector in its entirety, including the more complex process of adenoviral fiber modification to restrict viral tropism in order to achieve more efficient and specific gene delivery.

  20. Vector generator scan converter

    DOEpatents

    Moore, J.M.; Leighton, J.F.

    1988-02-05

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

  1. Vector generator scan converter

    DOEpatents

    Moore, James M.; Leighton, James F.

    1990-01-01

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  2. Laser Doppler anemometer measurements using nonorthogonal velocity components - Error estimates

    NASA Technical Reports Server (NTRS)

    Orloff, K. L.; Snyder, P. K.

    1982-01-01

    Laser Doppler anemometers (LDAs) that are arranged to measure nonorthogonal velocity components (from which orthogonal components are computed through transformation equations) are more susceptible to calibration and sampling errors than are systems with uncoupled channels. In this paper uncertainty methods and estimation theory are used to evaluate, respectively, the systematic and statistical errors that are present when such devices are applied to the measurement of mean velocities in turbulent flows. Statistical errors are estimated for two-channel LDA data that are either correlated or uncorrelated. For uncorrelated data the directional uncertainty of the measured velocity vector is considered for applications where mean streamline patterns are desired.

  3. Laser Doppler anemometer measurements using nonorthogonal velocity components: error estimates.

    PubMed

    Orloff, K L; Snyder, P K

    1982-01-15

    Laser Doppler anemometers (LDAs) that are arranged to measure nonorthogonal velocity components (from which orthogonal components are computed through transformation equations) are more susceptible to calibration and sampling errors than are systems with uncoupled channels. In this paper uncertainty methods and estimation theory are used to evaluate, respectively, the systematic and statistical errors that are present when such devices are applied to the measurement of mean velocities in turbulent flows. Statistical errors are estimated for two-channel LDA data that are either correlated or uncorrelated. For uncorrelated data the directional uncertainty of the measured velocity vector is considered for applications where mean streamline patterns are desired.

  4. Performance characteristics of a variable-area vane nozzle for vectoring an ASTOVL exhaust jet up to 45 deg

    NASA Technical Reports Server (NTRS)

    Mcardle, Jack G.; Esker, Barbara S.

    1993-01-01

    Many conceptual designs for advanced short-takeoff, vertical landing (ASTOVL) aircraft need exhaust nozzles that can vector the jet to provide forces and moments for controlling the aircraft's movement or attitude in flight near the ground. A type of nozzle that can both vector the jet and vary the jet flow area is called a vane nozzle. Basically, the nozzle consists of parallel, spaced-apart flow passages formed by pairs of vanes (vanesets) that can be rotated on axes perpendicular to the flow. Two important features of this type of nozzle are the abilities to vector the jet rearward up to 45 degrees and to produce less harsh pressure and velocity footprints during vertical landing than does an equivalent single jet. A one-third-scale model of a generic vane nozzle was tested with unheated air at the NASA Lewis Research Center's Powered Lift Facility. The model had three parallel flow passages. Each passage was formed by a vaneset consisting of a long and a short vane. The longer vanes controlled the jet vector angle, and the shorter controlled the flow area. Nozzle performance for three nominal flow areas (basic and plus or minus 21 percent of basic area), each at nominal jet vector angles from -20 deg (forward of vertical) to +45 deg (rearward of vertical) are presented. The tests were made with the nozzle mounted on a model tailpipe with a blind flange on the end to simulate a closed cruise nozzle, at tailpipe-to-ambient pressure ratios from 1.8 to 4.0. Also included are jet wake data, single-vaneset vector performance for long/short and equal-length vane designs, and pumping capability. The pumping capability arises from the subambient pressure developed in the cavities between the vanesets, which could be used to aspirate flow from a source such as the engine compartment. Some of the performance characteristics are compared with characteristics of a single-jet nozzle previously reported.

  5. Non-Colinearity of Angular Velocity and Angular Momentum

    ERIC Educational Resources Information Center

    Burr, A. F.

    1974-01-01

    Discusses the principles, construction, and operation of an apparatus which serves to demonstrate the non-colinearity of the angular velocity and momentum vectors as well as the inertial tensors. Applications of the apparatus to teaching of advanced undergraduate mechanics courses are recommended. (CC)

  6. Line Integral of a Vector.

    ERIC Educational Resources Information Center

    Balabanian, Norman

    This programed booklet is designed for the engineering student who understands and can use vector and unit vector notation, components of a vector, parallel law of vector addition, and the dot product of two vectors. Content begins with work done by a force in moving a body a certain distance along some path. For each of the examples and problem…

  7. Velocities in Solar Pores

    NASA Astrophysics Data System (ADS)

    Balasubramaniam, K. S.; Keil, S. L.; Smaldone, L. A.

    1996-05-01

    We investigate the three dimensional structure of solar pores and their surroundings using high spatial and spectral resolution data. We present evidence that surface velocities decrease around pores with a corresponding increase in the line-of-sight (LOS) velocities. LOS velocities in pores increase with the strength of the magnetic field. Surface velocities show convergence toward a weak downflow which appear to trace boundaries resembling meso-granular and super granular flows. The observed magnetic fields in the pores appear near these boundaries. We analyze the vertical velocity structure in pores and show that they generally have downflows decreasing exponentially with height, with a scale height of about 90 km. Evidence is also presented for the expanding nature of flux tubes. Finally we describe a phenomenological model for pores. This work was supported by AFOSR Task 2311G3. LAS was partially supported by the Progetto Nazionale Astrofisica e Fisica Cosmica of MURST and Scambi Internazionali of the Universita degli Studi di Napoli Frederico II. National Solar Observatory, NOAO, is operated for the National Science Foundation by AURA, Inc.

  8. Velocity-modulation atomization of liquid jets

    NASA Technical Reports Server (NTRS)

    Dressler, John L.

    1994-01-01

    A novel atomizer based on high-amplitude velocity atomization has been developed. Presently, the most common methods of atomization can use only the Rayleigh instability of a liquid cylinder and the Kelvin-Helmholtz instability of a liquid sheet. Our atomizer is capable of atomizing liquid jets by the excitation and destabilization of many other higher-order modes of surface deformation. The potential benefits of this sprayer are more uniform fuel air mixtures, faster fuel-air mixing, extended flow ranges for commercial nozzles, and the reduction of nozzle plugging by producing small drops from large nozzles.

  9. Observations of velocity shear driven plasma turbulence

    NASA Technical Reports Server (NTRS)

    Kintner, P. M., Jr.

    1976-01-01

    Electrostatic and magnetic turbulence observations from HAWKEYE-1 during the low altitude portion of its elliptical orbit over the Southern Hemisphere are presented. The magnetic turbulence is confined near the auroral zone and is similar to that seen at higher altitudes by HEOS-2 in the polar cusp. The electrostatic turbulence is composed of a background component with a power spectral index of 1.89 + or - .26 and an intense component with a power spectral index of 2.80 + or - .34. The intense electrostatic turbulence and the magnetic turbulence correlate with velocity shears in the convective plasma flow. Since velocity shear instabilities are most unstable to wave vectors perpendicular to the magnetic field, the shear correlated turbulence is anticipated to be two dimensional in character and to have a power spectral index of 3 which agrees with that observed in the intense electrostatic turbulence.

  10. Interferometric phase velocity measurements

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.; Labelle, J.; Kelley, M. C.; Cahill, L. J., Jr.; Moore, T.; Arnoldy, R.

    1984-01-01

    Phase velocities of plasma waves near the lower hybrid frequency were measured with an interferometer composed of two spatially separated electron-density probes. The plasma waves were produced in the F-region ionosphere by an argon ion beam. By calculating the normalized cross spectrum of the plasma waves a coherency of .98 was estimated along with a maximum phase difference of pi/3 radians between the two probes. This implies that the wavelength was 6 meters compared to an O(+) gyroradius of 3.8 meters, and that the phase velocity was 45 km/sec compared to an ion-beam velocity of 12.4 km/sec. These numbers compare favorably with recent predictions of a nonresonant mode produced by a dense ion beam.

  11. Fluidic angular velocity sensor

    NASA Technical Reports Server (NTRS)

    Berdahl, C. M. (Inventor)

    1986-01-01

    A fluidic sensor providing a differential pressure signal proportional to the angular velocity of a rotary input is described. In one embodiment the sensor includes a fluid pump having an impeller coupled to a rotary input. A housing forming a constricting fluid flow chamber is connected to the fluid input of the pump. The housing is provided with a fluid flow restrictive input to the flow chamber and a port communicating with the interior of the flow chamber. The differential pressure signal measured across the flow restrictive input is relatively noise free and proportional to the square of the angular velocity of the impeller. In an alternative embodiment, the flow chamber has a generally cylindrical configuration and plates having flow restrictive apertures are disposed within the chamber downstream from the housing port. In this embodiment, the differential pressure signal is found to be approximately linear with the angular velocity of the impeller.

  12. Shape functions for velocity interpolation in general hexahedral cells

    USGS Publications Warehouse

    Naff, R.L.; Russell, T.F.; Wilson, J.D.

    2002-01-01

    Numerical methods for grids with irregular cells require discrete shape functions to approximate the distribution of quantities across cells. For control-volume mixed finite-element (CVMFE) methods, vector shape functions approximate velocities and vector test functions enforce a discrete form of Darcy's law. In this paper, a new vector shape function is developed for use with irregular, hexahedral cells (trilinear images of cubes). It interpolates velocities and fluxes quadratically, because as shown here, the usual Piola-transformed shape functions, which interpolate linearly, cannot match uniform flow on general hexahedral cells. Truncation-error estimates for the shape function are demonstrated. CVMFE simulations of uniform and non-uniform flow with irregular meshes show first- and second-order convergence of fluxes in the L2 norm in the presence and absence of singularities, respectively.

  13. Baculovirus Transfer Vectors.

    PubMed

    Possee, Robert D; King, Linda A

    2016-01-01

    The production of a recombinant baculovirus expression vector normally involves mixing infectious virus DNA with a plasmid-based transfer vector and then co-transfecting insect cells to initiate virus infection. The aim of this chapter is to provide an update on the range of baculovirus transfer vectors currently available. Some of the original transfer vectors developed are now difficult to obtain but generally have been replaced by superior reagents. We focus on those that are available commercially and should be easy to locate. These vectors permit the insertion of single or multiple genes for expression, or the production of proteins with specific peptide tags that aid subsequent protein purification. Others have signal peptide coding regions permitting protein secretion or plasma membrane localization. A table listing the transfer vectors also includes information on the parental virus that should be used with each one. Methods are described for the direct insertion of a recombinant gene into the virus genome without the requirement for a transfer vector. The information provided should enable new users of the system to choose those reagents most suitable for their purposes.

  14. SGP and TWP (Manus) Ice Cloud Vertical Velocities

    DOE Data Explorer

    Kalesse, Heike

    2013-06-27

    Daily netcdf-files of ice-cloud dynamics observed at the ARM sites at SGP (Jan1997-Dec2010) and Manus (Jul1999-Dec2010). The files include variables at different time resolution (10s, 20min, 1hr). Profiles of radar reflectivity factor (dbz), Doppler velocity (vel) as well as retrieved vertical air motion (V_air) and reflectivity-weighted particle terminal fall velocity (V_ter) are given at 10s, 20min and 1hr resolution. Retrieved V_air and V_ter follow radar notation, so positive values indicate downward motion. Lower level clouds are removed, however a multi-layer flag is included.

  15. Velocity pump reaction turbine

    DOEpatents

    House, Palmer A.

    1984-01-01

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  16. Velocity pump reaction turbine

    DOEpatents

    House, Palmer A.

    1982-01-01

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  17. MSE velocity survey

    NASA Astrophysics Data System (ADS)

    Schimd, C.; Courtois, H.; Koda, J.

    2015-12-01

    A huge velocity survey based on the Maunakea Spectroscopic Explorer facility (MSE) is proposed, aiming at investigating the structure and dynamics of the cosmic web over 3π steradians up to ˜1 Gpc and at unprecedented spatial resolution, its relationship with the galaxy formation process, and the bias between galaxies and dark matter during the last three billions years. The cross-correlation of velocity and density fields will further allow the probe any deviation from General Relativity by measuring the the linear-growth rate of cosmic structures at precision competitive with high-redshift spectroscopic redshift surveys.

  18. Velocity pump reaction turbine

    SciTech Connect

    House, P.A.

    1984-02-07

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  19. Velocity pump reaction turbine

    SciTech Connect

    House, P.A.

    1982-06-01

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an interrotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal application

  20. Velocity pump reaction turbine

    DOEpatents

    House, P.A.

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  1. DVL Angular Velocity Recorder

    NASA Technical Reports Server (NTRS)

    Liebe, Wolfgang

    1944-01-01

    In many studies, especially of nonstationary flight motion, it is necessary to determine the angular velocities at which the airplane rotates about its various axes. The three-component recorder is designed to serve this purpose. If the angular velocity for one flight attitude is known, other important quantities can be derived from its time rate of change, such as the angular acceleration by differentiations, or - by integration - the angles of position of the airplane - that is, the angles formed by the airplane axes with the axis direction presented at the instant of the beginning of the motion that is to be investigated.

  2. Air modulation apparatus

    NASA Technical Reports Server (NTRS)

    Lenahan, D. T.; Corsmeier, R. J.; Sterman, A. P. (Inventor)

    1983-01-01

    An air modulation apparatus, such as for use in modulating cooling air to the turbine section of a gas turbine engine is described. The apparatus includes valve means disposed around an annular conduit, such as a nozzle, in the engine cooling air circuit. The valve means, when in a closed position, blocks a portion of the conduit, and thus reduces the amount and increases the velocity of cooling air flowing through the nozzle. The apparatus also includes actuation means, which can operate in response to predetermined engine conditions, for enabling opening and closing of the valve means.

  3. Rupture Velocities of Intermediate- and Deep-Focus Earthquakes

    NASA Astrophysics Data System (ADS)

    Warren, L. M.

    2014-12-01

    The rupture velocities of intermediate- and deep-focus earthquakes --- how they vary between subduction zones, how they vary with depth, and what their maximum values are --- may help constrain the mechanism(s) of the earthquakes. As part of a global study of intermediate- and deep-focus earthquakes, I have used rupture directivity to estimate the rupture vector (speed and orientation) for 422 earthquakes >70 km depth with MW ≥5.7 since 1990. I estimate the rupture velocity relative to the local P-wave velocity (vr/α). Since the same method is used for all earthquakes, the results can be readily compared across study areas. The study areas --- Middle America, South America, Tonga-Kermadec, Izu-Bonin-Marianas, and Japan-Kurils-Kamchatka --- include some of the warmest and coldest subduction zones: subducting plate ages range from 9-150 Myr and descent rates range from 1-13 cm/yr. Across all subduction zones and depth ranges, for the 193 earthquakes with observable directivity and well-constrained rupture vectors, most earthquakes rupture on the more horizontal of the two possible nodal planes. However, the rupture vectors appear to be randomly-oriented relative to the slip vector, so the earthquakes span the continuum from Mode II (i.e., parallel slip and rupture vectors) to Mode III rupture (i.e., perpendicular slip and rupture vectors). For this earthquake population, the mean rupture velocity is 0.43 vr/α ± 0.14 vr/α. The mean earthquake rupture velocities are similar between all subduction zones. Since the local seismic wavespeed is faster in colder subduction zones, absolute rupture velocities are faster in colder subduction zones. Overall, the fastest rupture velocities exceed the local S-wave speed. The supershear ruptures are associated with earthquakes closer to Mode II than Mode III faulting. This is consistent with theoretical calculations, which limit the rupture velocity to the S-wave speed for Mode III rupture but the P-wave speed for Mode II

  4. Evolution of velocity dispersion along cold collisionless flows

    SciTech Connect

    Banik, Nilanjan; Sikivie, Pierre

    2016-05-01

    We found that the infall of cold dark matter onto a galaxy produces cold collisionless flows and caustics in its halo. If a signal is found in the cavity detector of dark matter axions, the flows will be readily apparent as peaks in the energy spectrum of photons from axion conversion, allowing the densities, velocity vectors and velocity dispersions of the flows to be determined. We also discuss the evolution of velocity dispersion along cold collisionless flows in one and two dimensions. A technique is presented for obtaining the leading behaviour of the velocity dispersion near caustics. The results are used to derive an upper limit on the energy dispersion of the Big Flow from the sharpness of its nearby caustic, and a prediction for the dispersions in its velocity components.

  5. Evolution of velocity dispersion along cold collisionless flows

    DOE PAGES

    Banik, Nilanjan; Sikivie, Pierre

    2016-05-01

    We found that the infall of cold dark matter onto a galaxy produces cold collisionless flows and caustics in its halo. If a signal is found in the cavity detector of dark matter axions, the flows will be readily apparent as peaks in the energy spectrum of photons from axion conversion, allowing the densities, velocity vectors and velocity dispersions of the flows to be determined. We also discuss the evolution of velocity dispersion along cold collisionless flows in one and two dimensions. A technique is presented for obtaining the leading behaviour of the velocity dispersion near caustics. The results aremore » used to derive an upper limit on the energy dispersion of the Big Flow from the sharpness of its nearby caustic, and a prediction for the dispersions in its velocity components.« less

  6. Null Killing vectors

    NASA Astrophysics Data System (ADS)

    Lukács, B.; Perjés, Z.; Sebestyén, Á.

    1981-06-01

    Space-times admitting a null Killing vector are studied, using the Newman-Penrose spin coefficient formalism. The properties of the eigenrays (principal null curves of the Killing bivector) are shown to be related to the twist of the null Killing vector. Among the electrovacs, the ones containing a null Maxwell field turn out to belong to the twist-free class. An electrovac solution is obtained for which the null Killing vector is twisting and has geodesic and shear-free eigenrays. This solution is parameterless and appears to be the field of a zero-mass, spinning, and charged source.

  7. Modeling Terminal Velocity

    ERIC Educational Resources Information Center

    Brand, Neal; Quintanilla, John A.

    2013-01-01

    Using a simultaneously falling softball as a stopwatch, the terminal velocity of a whiffle ball can be obtained to surprisingly high accuracy with only common household equipment. This classroom activity engages students in an apparently daunting task that nevertheless is tractable, using a simple model and mathematical techniques at their…

  8. Vectoring of parallel synthetic jets: A parametric study

    NASA Astrophysics Data System (ADS)

    Berk, Tim; Gomit, Guillaume; Ganapathisubramani, Bharathram

    2016-11-01

    The vectoring of a pair of parallel synthetic jets can be described using five dimensionless parameters: the aspect ratio of the slots, the Strouhal number, the Reynolds number, the phase difference between the jets and the spacing between the slots. In the present study, the influence of the latter four on the vectoring behaviour of the jets is examined experimentally using particle image velocimetry. Time-averaged velocity maps are used to study the variations in vectoring behaviour for a parametric sweep of each of the four parameters independently. A topological map is constructed for the full four-dimensional parameter space. The vectoring behaviour is described both qualitatively and quantitatively. A vectoring mechanism is proposed, based on measured vortex positions. We acknowledge the financial support from the European Research Council (ERC Grant Agreement No. 277472).

  9. Volumetric Acoustic Vector Intensity Probe

    NASA Technical Reports Server (NTRS)

    Klos, Jacob

    2006-01-01

    A new measurement tool capable of imaging the acoustic intensity vector throughout a large volume is discussed. This tool consists of an array of fifty microphones that form a spherical surface of radius 0.2m. A simultaneous measurement of the pressure field across all the microphones provides time-domain near-field holograms. Near-field acoustical holography is used to convert the measured pressure into a volumetric vector intensity field as a function of frequency on a grid of points ranging from the center of the spherical surface to a radius of 0.4m. The volumetric intensity is displayed on three-dimensional plots that are used to locate noise sources outside the volume. There is no restriction on the type of noise source that can be studied. The sphere is mobile and can be moved from location to location to hunt for unidentified noise sources. An experiment inside a Boeing 757 aircraft in flight successfully tested the ability of the array to locate low-noise-excited sources on the fuselage. Reference transducers located on suspected noise source locations can also be used to increase the ability of this device to separate and identify multiple noise sources at a given frequency by using the theory of partial field decomposition. The frequency range of operation is 0 to 1400Hz. This device is ideal for the study of noise sources in commercial and military transportation vehicles in air, on land and underwater.

  10. Targeted adenoviral vectors

    NASA Astrophysics Data System (ADS)

    Douglas, Joanne T.

    The practical implementation of gene therapy in the clinical setting mandates gene delivery vehicles, or vectors, capable of efficient gene delivery selectively to the target disease cells. The utility of adenoviral vectors for gene therapy is restricted by their dependence on the native adenoviral primary cellular receptor for cell entry. Therefore, a number of strategies have been developed to allow CAR-independent infection of specific cell types, including the use of bispecific conjugates and genetic modifications to the adenoviral capsid proteins, in particular the fibre protein. These targeted adenoviral vectors have demonstrated efficient gene transfer in vitro , correlating with a therapeutic benefit in preclinical animal models. Such vectors are predicted to possess enhanced efficacy in human clinical studies, although anatomical barriers to their use must be circumvented.

  11. The Vector Decomposition Problem

    NASA Astrophysics Data System (ADS)

    Yoshida, Maki; Mitsunari, Shigeo; Fujiwara, Toru

    This paper introduces a new computational problem on a two-dimensional vector space, called the vector decomposition problem (VDP), which is mainly defined for designing cryptosystems using pairings on elliptic curves. We first show a relation between the VDP and the computational Diffie-Hellman problem (CDH). Specifically, we present a sufficient condition for the VDP on a two-dimensional vector space to be at least as hard as the CDH on a one-dimensional subspace. We also present a sufficient condition for the VDP with a fixed basis to have a trapdoor. We then give an example of vector spaces which satisfy both sufficient conditions and on which the CDH is assumed to be hard in previous work. In this sense, the intractability of the VDP is a reasonable assumption as that of the CDH.

  12. Saccharomyces cerevisiae Shuttle vectors.

    PubMed

    Gnügge, Robert; Rudolf, Fabian

    2017-01-10

    Yeast shuttle vectors are indispensable tools in yeast research. They enable cloning of defined DNA sequences in Escherichia coli and their direct transfer into Saccharomyces cerevisiae cells. There are three types of commonly used yeast shuttle vectors: centromeric plasmids, episomal plasmids and integrating plasmids. In this review, we discuss the different plasmid systems and their characteristic features. We focus on their segregational stability and copy number and indicate how to modify these properties. Copyright © 2017 John Wiley & Sons, Ltd.

  13. Poynting-vector filter

    SciTech Connect

    Carrigan, Charles R.

    2011-08-02

    A determination is made of frequency components associated with a particular bearing or location resulting from sources emitting electromagnetic-wave energy for which a Poynting-Vector can be defined. The broadband frequency components associated with a specific direction or location of interest are isolated from other components in the power spectrum that are not associated with the direction or location of interest. The collection of pointing vectors can be used to characterize the source.

  14. Bloch vector projection noise

    NASA Technical Reports Server (NTRS)

    Wang, Li-Jun; Bacon, A. M.; Zhao, H.-Z.; Thomas, J. E.

    1994-01-01

    In the optical measurement of the Bloch vector components describing a system of N two-level atoms, the quantum fluctuations in these components are coupled into the measuring optical field. This paper develops the quantum theory of optical measurement of Bloch vector projection noise. The preparation and probing of coherence in an effective two-level system consisting of the two ground states in an atomic three-level lambda-scheme are analyzed.

  15. Cape Canaveral Air Force Station, Launch Complex 39, Solid Rocket ...

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

    Cape Canaveral Air Force Station, Launch Complex 39, Solid Rocket Booster Disassembly & Refurbishment Complex, Thrust Vector Control Deservicing Facility, Hangar Road, Cape Canaveral, Brevard County, FL

  16. Extraction of the local phase velocity and the group velocity from surface noise source in microseismic monitoring.

    NASA Astrophysics Data System (ADS)

    Chmiel, Malgorzata; Roux, Philippe; Bardainne, Thomas

    2015-04-01

    The aim of this work is to demonstrate the extraction of the local phase velocity and the group velocity from surface noise source in microseismic monitoring. One of the biggest challenges in microseismic monitoring is surface seismic noise. Microseismic surface studies are often contaminated with instrumental and ambient seismic noise, originating from both natural (wind, rain) and anthropogenic sources (injection, pumps, infrastructure, traffic). The two primary ways to attenuate the undesired surface noise sources are via processing and acquisition strategies. At the acquisition stage, one solution is through the use of patch array. One patch is a group of 48 vertical sensors densely distributed on the area of~150m*150m, and one trace is the array of 12 vertical geophones. In the present work, 44 patches were sparsely distributed on a 41 square kilometer area. Benefitting from continuous recording, we used Matched Field Processing (MFP) methods to extract local phase and group velocities over the whole area. The aim of this technique is to detect and locate uncoherent noise sources while using array-processing methods. The method is based on the comparison between a recorded wave field per patch (the data vector) and a theoretical (or modeled) wave-field (the replica vector) in the frequency domain. The replica vector is a Green's function at a given frequency, which depends on the following parameters: position (x,y) in 2D-grid and a phase velocity. The noise source location is obtained by matching the data vector with the replica vector using a linear "low-resolution" algorithm or a nonlinear "high-resolution" adaptive processor. These algorithms are defined for each point in the 2D - grid and for each phase velocity. The phase velocity per patch is optimal if it maximizes the processor output. As a result, an ambiguity surface is produced which shows the probability of presence of primary noise sources per patch. The combination of all the maps per patch

  17. A vector wave equation for neutrinos

    NASA Astrophysics Data System (ADS)

    Reifler, Frank

    1984-04-01

    The Cartan map gives an isomorphism between spinors and isotropic vectors. Isotropic vectors F=E+iH satisfy the condition F ṡ F=0. We show that via the Cartan map, the particle current for neutrinos is given by j0=||E||, j=E×H/||E||, and the neutrino wave equation becomes D0F=iD×F-(DF) ṡ v, where v=j/j0=E×H/E2=velocity field, D0=i(h/2)(∂/∂t)-V0,D=-i (h/2)∇-V, where h=Planck's constant and V=(V0,V)=external potential. This wave equation preserves the isotropic condition, and like the equivalent Dirac equation, causes j to be the conserved current. We show that the isotropic restriction on the vector field F accounts for the observable properties of a neutrino in an external field, in particular, for the observed spectrum of the energy, momentum, angular momentum, spin, velocity, and position operators.

  18. Fall velocity of multi-shaped clasts

    NASA Astrophysics Data System (ADS)

    Le Roux, Jacobus P.

    2014-12-01

    Accurate settling velocity predictions of differently shaped micro- or macroclasts are required in many branches of science and engineering. Here, a single, dimensionally correct equation is presented that yields a significant improvement on previous settling formulas for a wide range of clast shapes. For smooth or irregular clasts with known axial dimensions, a partially polynomial equation based on the logarithmic values of dimensionless sizes and settling velocities is presented, in which the values of only one coefficient and one exponent need to be adapted for different shapes, irrespective of the Reynolds number. For irregular, natural clasts with unknown axial dimensions, a polynomial equation of the same form is applied, but with different coefficients. Comparison of the predicted and measured settling velocities of 8 different shape classes as well as natural grains with unknown axial dimensions in liquids, representing a total of 390 experimental data points, shows a mean percentage error of - 0.83% and a combined R2 value of 0.998. The settling data of 169 differently shaped particles of pumice, glass and feldspar falling in air were also analyzed, which demonstrates that the proposed equation is also valid for these conditions. Two additional shape classes were identified in the latter data set, although the resultant equations are less accurate than for liquids. An Excel spreadsheet is provided to facilitate the calculation of fall velocities for grains settling individually and in groups, or alternatively to determine the equivalent sieve size from the settling velocity, which can be used to calibrate settling tubes.

  19. Syngeneic AAV pseudo-vectors potentiates full vector transduction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An excessive amount of empty capsids are generated during regular AAV vector production process. These pseudo-vectors often remain in final vectors used for animal studies or clinical trials. The potential effects of these pseudo-vectors on AAV transduction have been a major concern. In the current ...

  20. Kinematic and diabatic vertical velocity climatologies from a chemistry climate model

    NASA Astrophysics Data System (ADS)

    Marinke Hoppe, Charlotte; Ploeger, Felix; Konopka, Paul; Müller, Rolf

    2016-05-01

    The representation of vertical velocity in chemistry climate models is a key element for the representation of the large-scale Brewer-Dobson circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model. The calculation of kinematic vertical velocity is based on the continuity equation, whereas diabatic vertical velocity is computed using diabatic heating rates. Annual and monthly zonal mean climatologies of vertical velocity from a 10-year simulation are provided for both kinematic and diabatic vertical velocity representations. In general, both vertical velocity patterns show the main features of the stratospheric circulation, namely, upwelling at low latitudes and downwelling at high latitudes. The main difference in the vertical velocity pattern is a more uniform structure for diabatic and a noisier structure for kinematic vertical velocity. Diabatic vertical velocities show higher absolute values both in the upwelling branch in the inner tropics and in the downwelling regions in the polar vortices. Further, there is a latitudinal shift of the tropical upwelling branch in boreal summer between the two vertical velocity representations with the tropical upwelling region in the diabatic representation shifted southward compared to the kinematic case. Furthermore, we present mean age of air climatologies from two transport schemes in EMAC using these different vertical velocities and analyze the impact of residual circulation and mixing processes on the age of air. The age of air distributions show a hemispheric difference pattern in the stratosphere with younger air in the Southern Hemisphere and older air in the Northern Hemisphere using the transport scheme with diabatic vertical velocities. Further, the age of air climatology from the transport scheme using diabatic vertical velocities shows a younger mean age of air in the

  1. Reliable Diameter Control of Carbon Nanotube Nanobundles Using Withdrawal Velocity.

    PubMed

    Shin, Jung Hwal; Kim, Kanghyun; An, Taechang; Choi, WooSeok; Lim, Geunbae

    2016-12-01

    Carbon nanotube (CNT) nanobundles are widely used in nanoscale imaging, fabrication, and electrochemical and biological sensing. The diameter of CNT nanobundles should be controlled precisely, because it is an important factor in determining electrode performance. Here, we fabricated CNT nanobundles on tungsten tips using dielectrophoresis (DEP) force and controlled their diameters by varying the withdrawal velocity of the tungsten tips. Withdrawal velocity pulling away from the liquid-air interface could be an important, reliable parameter to control the diameter of CNT nanobundles. The withdrawal velocity was controlled automatically and precisely with a one-dimensional motorized stage. The effect of the withdrawal velocity on the diameter of CNT nanobundles was analyzed theoretically and compared with the experimental results. Based on the attachment efficiency, the withdrawal velocity is inversely proportional to the diameter of the CNT nanobundles; this has been demonstrated experimentally. Control of the withdrawal velocity will play an important role in fabricating CNT nanobundles using DEP phenomena.

  2. Air pollution from aircraft

    NASA Technical Reports Server (NTRS)

    Heywood, J. B.; Fay, J. A.; Chigier, N. A.

    1979-01-01

    A series of fundamental problems related to jet engine air pollution and combustion were examined. These include soot formation and oxidation, nitric oxide and carbon monoxide emissions mechanisms, pollutant dispension, flow and combustion characteristics of the NASA swirl can combustor, fuel atomization and fuel-air mixing processes, fuel spray drop velocity and size measurement, ignition and blowout. A summary of this work, and a bibliography of 41 theses and publications which describe this work, with abstracts, is included.

  3. Draft air deflecting device

    SciTech Connect

    Riley, J.E.

    1982-05-18

    A draft air deflecting device is mountable proximate to a window contained in a firebox and serves as a conduit which directs draft air across the inner surface of the window prior to its supporting combustion of the fuel in the firebox. In this respect , the draft air deflecting device is formed as a box which communicates with draft air holes located in the firebox and which includes a forwardly extending lip serving to define a nozzle for both increasing the velocity and directing the incoming draft air across the firebox window. The incoming draft air is thus utilized to cool and to prevent soot, creosote and other particulates from accumulating on the window.

  4. Vector and Axial Vector Pion Form Factors

    NASA Astrophysics Data System (ADS)

    Vitz, Michael; PEN Collaboration

    2015-04-01

    Radiative pion decay π+ -->e+ νγ (RPD) provides critical input to chiral perturbation theory (χPT). Aside from the uninteresting ``inner bremsstrahlung'' contribution from QED, the RPD rate contains ``structure dependent'' terms given by FV and FA, the vector and axial-vector pion form factors, respectively. The two appear in the decay rate in combinations FV -FA and FV +FA , i.e., in the so-called SD- and SD+ terms, respectively. The latter has been measured to high precision by the PIBETA collaboration. We report on the analysis of new data, measured by the PEN collaboration in runs between 2008 and 2010 at the Paul Scherrer Institute, Switzerland. We particularly focus on the possibility of improvement in the determination of the SD- term. Precise determinations of FV and FA test the validity of the CVC hypothesis, provide numerical input for the l9 +l10 terms in the χPT lagrangian, and constrain potential non-(V - A) terms, such as a possible tensor term FT. NSF grants PHY-0970013, 1307328, and others.

  5. Bunyavirus-vector interactions.

    PubMed

    Beaty, B J; Bishop, D H

    1988-06-01

    Recent advances in the genetics and molecular biology of bunyaviruses have been applied to understanding bunyavirus-vector interactions. Such approaches have revealed which virus gene and gene products are important in establishing infections in vectors and in transmission of viruses. However, much more information is required to understand the molecular mechanisms of persistent infections of vectors which are lifelong but apparently exert no untoward effect. In fact, it seems remarkable that LAC viral antigen can be detected in almost every cell in an ovarian follicle, yet no untoward effect on fecundity and no teratology is seen. Similarly the lifelong infection of the vector would seem to provide ample opportunity for bunyavirus evolution by genetic drift and, under the appropriate circumstances, by segment reassortment. The potential for bunyavirus evolution by segment reassortment in vectors certainly exists. For example the Group C viruses in a small forest in Brazil seem to constitute a gene pool, with the 6 viruses related alternately by HI/NT and CF reactions, which assay respectively M RNA and S RNA gene products (Casals and Whitman, 1960; Shope and Causey, 1962). Direct evidence for naturally occurring reassortant bunyaviruses has also been obtained. Oligonucleotide fingerprint analyses of field isolates of LAC virus and members of the Patois serogroup of bunyaviruses have demonstrated that reassortment does occur in nature (El Said et al., 1979; Klimas et al., 1981; Ushijima et al., 1981). Determination of the genotypic frequencies of viruses selected by the biological interactions of viruses and vectors after dual infection and segment reassortment is an important issue. Should a virus result that efficiently interacts with alternate vector species, the virus could be expressed in different circumstances with serious epidemiologic consequences. Dual infection of vectors with different viruses is not unlikely, because many bunyaviruses are sympatric in

  6. Bodies Falling with Air Resistance: Computer Simulation.

    ERIC Educational Resources Information Center

    Vest, Floyd

    1982-01-01

    Two models are presented. The first assumes that air resistance is proportional to the velocity of the falling body. The second assumes that air resistance is proportional to the square of the velocity. A program written in BASIC that simulates the second model is presented. (MP)

  7. A vector scanning processing technique for pulsed laser velocimetry

    NASA Astrophysics Data System (ADS)

    Wernet, Mark P.; Edwards, Robert V.

    1989-03-01

    Pulsed laser sheet velocimetry yields nonintrusive measurements of two-dimensional velocity vectors across an extended planar region of a flow. Current processing techniques offer high precision (1 pct) velocity estimates, but can require several hours of processing time on specialized array processors. Under some circumstances, a simple, fast, less accurate (approx. 5 pct), data reduction technique which also gives unambiguous velocity vector information is acceptable. A direct space domain processing technique was examined. The direct space domain processing technique was found to be far superior to any other techniques known, in achieving the objectives listed above. It employs a new data coding and reduction technique, where the particle time history information is used directly. Further, it has no 180 deg directional ambiguity. A complex convection vortex flow was recorded and completely processed in under 2 minutes on an 80386 based PC, producing a 2-D velocity vector map of the flow field. Hence, using this new space domain vector scanning (VS) technique, pulsed laser velocimetry data can be reduced quickly and reasonably accurately, without specialized array processing hardware.

  8. Vectored Thrust Digital Flight Control for Crew Escape. Volume 2.

    DTIC Science & Technology

    1985-12-01

    general the roll euler angle is essentially a " free " control variable since rotations about the velocity vector induce no injurious force and torque...400 +200 -200 - i +200 -200 radicl ion +1 - acceleration radical Figure 7.63 MIL 2 (Table 1) 339 u t=OUstt=S +2000 n *" Q ~ f 2 7- _7- dynornic

  9. Satellite Angular Rate Estimation From Vector Measurements

    NASA Technical Reports Server (NTRS)

    Azor, Ruth; Bar-Itzhack, Itzhack Y.; Harman, Richard R.

    1996-01-01

    This paper presents an algorithm for estimating the angular rate vector of a satellite which is based on the time derivatives of vector measurements expressed in a reference and body coordinate. The computed derivatives are fed into a spacial Kalman filter which yields an estimate of the spacecraft angular velocity. The filter, named Extended Interlaced Kalman Filter (EIKF), is an extension of the Kalman filter which, although being linear, estimates the state of a nonlinear dynamic system. It consists of two or three parallel Kalman filters whose individual estimates are fed to one another and are considered as known inputs by the other parallel filter(s). The nonlinear dynamics stem from the nonlinear differential equation that describes the rotation of a three dimensional body. Initial results, using simulated data, and real Rossi X ray Timing Explorer (RXTE) data indicate that the algorithm is efficient and robust.

  10. Energy Velocity Defined by Brillouin

    NASA Astrophysics Data System (ADS)

    Hosono, Hiroyuki; Hosono, Toshio

    The physical meaning of the energy velocity in lossy Lorentz media is clarified. First, two expressions for the energy velocity, one by Brillouin and another by Diener, are examined. We show that, while Diener's is disqualified, Brillouin's is acceptable as energy velocity. Secondly, we show that the signal velocity defined by Brillouin and Baerwald is exactly identical with the Brillouin's energy velocity. Thirdly, by using triangle-modulated harmonic wave, we show that the superluminal group velocity plays its role as a revelator only after the arrival of the signal traveling at the subluminal energy velocity. In short, nothing moves at the group velocity, and every frequency component of a signal propagates at its own energy velocity.

  11. Air Research

    EPA Pesticide Factsheets

    EPA's air research provides the critical science to develop and implement outdoor air regulations under the Clean Air Act and puts new tools and information in the hands of air quality managers and regulators to protect the air we breathe.

  12. Laser transit anemometer measurements of a JANNAF nozzle base velocity flow field

    NASA Technical Reports Server (NTRS)

    Hunter, William W., Jr.; Russ, C. E., Jr.; Clemmons, J. I., Jr.

    1990-01-01

    Velocity flow fields of a nozzle jet exhausting into a supersonic flow were surveyed. The measurements were obtained with a laser transit anemometer (LTA) system in the time domain with a correlation instrument. The LTA data is transformed into the velocity domain to remove the error that occurs when the data is analyzed in the time domain. The final data is shown in velocity vector plots for positions upstream, downstream, and in the exhaust plane of the jet nozzle.

  13. Vector financial rogue waves

    NASA Astrophysics Data System (ADS)

    Yan, Zhenya

    2011-11-01

    The coupled nonlinear volatility and option pricing model presented recently by Ivancevic is investigated, which generates a leverage effect, i.e., stock volatility is (negatively) correlated to stock returns, and can be regarded as a coupled nonlinear wave alternative of the Black-Scholes option pricing model. In this Letter, we analytically propose vector financial rogue waves of the coupled nonlinear volatility and option pricing model without an embedded w-learning. Moreover, we exhibit their dynamical behaviors for chosen different parameters. The vector financial rogue wave (rogon) solutions may be used to describe the possible physical mechanisms for the rogue wave phenomena and to further excite the possibility of relative researches and potential applications of vector rogue waves in the financial markets and other related fields.

  14. 3-D Velocity Measurement of Natural Convection Using Image Processing

    NASA Astrophysics Data System (ADS)

    Shinoki, Masatoshi; Ozawa, Mamoru; Okada, Toshifumi; Kimura, Ichiro

    This paper describes quantitative three-dimensional measurement method for flow field of a rotating Rayleigh-Benard convection in a cylindrical cell heated below and cooled above. A correlation method for two-dimensional measurement was well advanced to a spatio-temporal correlation method. Erroneous vectors, often appeared in the correlation method, was successfully removed using Hopfield neural network. As a result, calculated 3-D velocity vector distribution well corresponded to the observed temperature distribution. Consequently, the simultaneous three-dimensional measurement system for temperature and flow field was developed.

  15. Kinematic and diabatic vertical velocity climatologies from a chemistry climate model

    NASA Astrophysics Data System (ADS)

    Hoppe, C. M.; Ploeger, F.; Konopka, P.; Müller, R.

    2015-11-01

    The representation of vertical velocity in chemistry climate models is a key element for the representation of the large scale Brewer-Dobson-Circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Messy Atmospheric Chemistry (EMAC) model. The calculation of kinematic vertical velocity is based on the continuity equation, whereas diabatic vertical velocity is computed using diabatic heating rates. Annual and monthly zonal mean climatologies of vertical velocity from a 10 year simulation are provided for both, kinematic and diabatic vertical velocity representations. In general, both vertical velocity patterns show the main features of the stratospheric circulation, namely upwelling at low latitudes and downwelling at high latitudes. The main difference in the vertical velocity pattern is a more uniform structure for diabatic and a noisier structure for kinematic vertical velocity. Diabatic vertical velocities show higher absolute values both in the upwelling branch in the inner tropics and in the downwelling regions in the polar vortices. Further, there is a latitudinal shift of the tropical upwelling branch in boreal summer between the two vertical velocity representations with the tropical upwelling region in the diabatic representation shifted southward compared to the kinematic case. Furthermore, we present mean age of air climatologies from two transport schemes in EMAC using these different vertical velocities. The age of air distributions show a hemispheric difference pattern in the stratosphere with younger air in the Southern Hemisphere and older air in the Northern Hemisphere using the transport scheme with diabatic vertical velocities. Further, the age of air climatology from the transport scheme using diabatic vertical velocities shows younger mean age of air in the inner tropical upwelling branch and older mean age in the extratopical tropopause region.

  16. Acoustic velocity meter systems

    USGS Publications Warehouse

    Laenen, Antonius

    1985-01-01

    Acoustic velocity meter (AVM) systems operate on the principles that the point-to-point upstream traveltime of an acoustic pulse is longer than the downstream traveltime and that this difference in traveltime can be accurately measured by electronic devices. An AVM system is capable of recording water velocity (and discharge) under a wide range of conditions, but some constraints apply: 1. Accuracy is reduced and performance is degraded if the acoustic path is not a continuous straight line. The path can be bent by reflection if it is too close to a stream boundary or by refraction if it passes through density gradients resulting from variations in either water temperature or salinity. For paths of less than 100 m, a temperature gradient of 0.1' per meter causes signal bending less than 0.6 meter at midchannel, and satisfactory velocity results can be obtained. Reflection from stream boundaries can cause signal cancellation if boundaries are too close to signal path. 2. Signal strength is attenuated by particles or bubbles that absorb, spread, or scatter sound. The concentration of particles or bubbles that can be tolerated is a function of the path length and frequency of the acoustic signal. 3. Changes in streamline orientation can affect system accuracy if the variability is random. 4. Errors relating to signal resolution are much larger for a single threshold detection scheme than for multiple threshold schemes. This report provides methods for computing the effect of various conditions on the accuracy of a record obtained from an AVM. The equipment must be adapted to the site. Field reconnaissance and preinstallation analysis to detect possible problems are critical for proper installation and operation of an AVM system.

  17. 30 CFR 75.350 - Belt air course ventilation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... except as provided in paragraph (c) of this section. (2) Effective December 31, 2009, the air velocity in... manager may approve lower velocities in the ventilation plan based on specific mine conditions. Air velocities must be compatible with all fire detection systems and fire suppression systems used in the...

  18. 30 CFR 75.350 - Belt air course ventilation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... except as provided in paragraph (c) of this section. (2) Effective December 31, 2009, the air velocity in... manager may approve lower velocities in the ventilation plan based on specific mine conditions. Air velocities must be compatible with all fire detection systems and fire suppression systems used in the...

  19. 30 CFR 75.350 - Belt air course ventilation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... except as provided in paragraph (c) of this section. (2) Effective December 31, 2009, the air velocity in... manager may approve lower velocities in the ventilation plan based on specific mine conditions. Air velocities must be compatible with all fire detection systems and fire suppression systems used in the...

  20. 30 CFR 75.350 - Belt air course ventilation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... except as provided in paragraph (c) of this section. (2) Effective December 31, 2009, the air velocity in... manager may approve lower velocities in the ventilation plan based on specific mine conditions. Air velocities must be compatible with all fire detection systems and fire suppression systems used in the...

  1. Scalar-vector bootstrap

    NASA Astrophysics Data System (ADS)

    Rejon-Barrera, Fernando; Robbins, Daniel

    2016-01-01

    We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.

  2. Bunyavirus-Vector Interactions

    PubMed Central

    Horne, Kate McElroy; Vanlandingham, Dana L.

    2014-01-01

    The Bunyaviridae family is comprised of more than 350 viruses, of which many within the Hantavirus, Orthobunyavirus, Nairovirus, Tospovirus, and Phlebovirus genera are significant human or agricultural pathogens. The viruses within the Orthobunyavirus, Nairovirus, and Phlebovirus genera are transmitted by hematophagous arthropods, such as mosquitoes, midges, flies, and ticks, and their associated arthropods not only serve as vectors but also as virus reservoirs in many cases. This review presents an overview of several important emerging or re-emerging bunyaviruses and describes what is known about bunyavirus-vector interactions based on epidemiological, ultrastructural, and genetic studies of members of this virus family. PMID:25402172

  3. Tomographic Particle Localization and Velocity Measurement

    NASA Astrophysics Data System (ADS)

    Kirner, S.; Forster, G.; Schein, J.

    2015-01-01

    Wire arc spraying is one of the most common and elementary thermal spray processes. Due to its easy handling, high deposition rate, and relative low process costs, it is a frequently used coating technology for the production of wear and corrosion resistant coatings. In order to produce reliable and reproducible coatings, it is necessary to be able to control the coating process. This can be achieved by analyzing the parameters of the particles deposited. Essential for the coating quality are, for example, the velocity, the size, and the temperature of the particles. In this work, an innovative diagnostic for particle velocity and location determination is presented. By the use of several synchronized CMOS-Cameras positioned around the particle jet, a series of images from different directions is simultaneously taken. The images contain the information that is necessary to calculate the 3D-location-vector of the particles and finally with the help of the exposure time the trajectory can be determined. In this work, the experimental setup of the tomographic diagnostic is presented, the mathematical method of the reconstruction is explained, and first measured velocity distributions are shown.

  4. Applications Using AIRS Data

    NASA Astrophysics Data System (ADS)

    Ray, S. E.; Pagano, T. S.; Fetzer, E. J.; Lambrigtsen, B.; Olsen, E. T.; Teixeira, J.; Licata, S. J.; Hall, J. R.; Thompson, C. K.

    2015-12-01

    The Atmospheric Infrared Sounder (AIRS) on NASA's Aqua spacecraft has been returning daily global observations of Earth's atmospheric constituents and properties since 2002. With a 12-year data record and daily, global observations in near real-time, AIRS data can play a role in applications that fall under many of the NASA Applied Sciences focus areas. For vector-borne disease, research is underway using AIRS near surface retrievals to assess outbreak risk, mosquito incubation periods and epidemic potential for dengue fever, malaria, and West Nile virus. For drought applications, AIRS temperature and humidity data are being used in the development of new drought indicators and improvement in the understanding of drought development. For volcanic hazards, new algorithms using AIRS data are in development to improve the reporting of sulfur dioxide concentration, the burden and height of volcanic ash and dust, all of which pose a safety threat to aircraft. In addition, anomaly maps of many of AIRS standard products are being produced to help highlight "hot spots" and illustrate trends. To distribute it's applications imagery, AIRS is leveraging existing NASA data frameworks and organizations to facilitate archiving, distribution and participation in the BEDI. This poster will communicate the status of the applications effort for the AIRS Project and provide examples of new maps designed to best communicate the AIRS data.

  5. Attenuated Vector Tomography -- An Approach to Image Flow Vector Fields with Doppler Ultrasonic Imaging

    SciTech Connect

    Huang, Qiu; Peng, Qiyu; Huang, Bin; Cheryauka, Arvi; Gullberg, Grant T.

    2008-05-15

    The measurement of flow obtained using continuous wave Doppler ultrasound is formulated as a directional projection of a flow vector field. When a continuous ultrasound wave bounces against a flowing particle, a signal is backscattered. This signal obtains a Doppler frequency shift proportional to the speed of the particle along the ultrasound beam. This occurs for each particle along the beam, giving rise to a Doppler velocity spectrum. The first moment of the spectrum provides the directional projection of the flow along theultrasound beam. Signals reflected from points further away from the detector will have lower amplitude than signals reflected from points closer to the detector. The effect is very much akin to that modeled by the attenuated Radon transform in emission computed tomography.A least-squares method was adopted to reconstruct a 2D vector field from directional projection measurements. Attenuated projections of only the longitudinal projections of the vector field were simulated. The components of the vector field were reconstructed using the gradient algorithm to minimize a least-squares criterion. This result was compared with the reconstruction of longitudinal projections of the vector field without attenuation. Ifattenuation is known, the algorithm was able to accurately reconstruct both components of the full vector field from only one set of directional projection measurements. A better reconstruction was obtained with attenuation than without attenuation implying that attenuation provides important information for the reconstruction of flow vector fields.This confirms previous work where we showed that knowledge of the attenuation distribution helps in the reconstruction of MRI diffusion tensor fields from fewer than the required measurements. In the application of ultrasound the attenuation distribution is obtained with pulse wave transmission computed tomography and flow information is obtained with continuous wave Doppler.

  6. Neutron Velocity Selector

    NASA Astrophysics Data System (ADS)

    Fermi, Enrico

    This Patent presents a detailed description of the construction and operation of a velocity selector for neutrons with velocities up to 6000÷7000 m/s. This apparatus employs a rotating shutter designed in such a way that neutrons are passed during a portion of each rotation of the shutter, the shutter blocking all neutron radiation at other times. The selector is built up with alternate laminations of a material with high neutron capture cross section (such as, for example, cadmium, boron or gadolinium), and parallel laminations of a material with low capture probability (such as, for example, aluminium, magnesium or beryllium). This is required in order to provide a path through the shutter to the neutrons, which then pass into a ionization chamber. The timing mechanism, adopted to activate or deactivate the neutron detection, and measuring means at given times following each opening or closing of the shutter, is electronic (not mechanic), controlled by a photocell unit. The reference published article for the main topic of the present Patent is [Fermi (1947)].

  7. Designing plasmid vectors.

    PubMed

    Tolmachov, Oleg

    2009-01-01

    Nonviral gene therapy vectors are commonly based on recombinant bacterial plasmids or their derivatives. The plasmids are propagated in bacteria, so, in addition to their therapeutic cargo, they necessarily contain a bacterial replication origin and a selection marker, usually a gene conferring antibiotic resistance. Structural and maintenance plasmid stability in bacteria is required for the plasmid DNA production and can be achieved by carefully choosing a combination of the therapeutic DNA sequences, replication origin, selection marker, and bacterial strain. The use of appropriate promoters, other regulatory elements, and mammalian maintenance devices ensures that the therapeutic gene or genes are adequately expressed in target human cells. Optimal immune response to the plasmid vectors can be modulated via inclusion or exclusion of DNA sequences containing immunostimulatory CpG sequence motifs. DNA fragments facilitating construction of plasmid vectors should also be considered for inclusion in the design of plasmid vectors. Techniques relying on site-specific or homologous recombination are preferred for construction of large plasmids (>15 kb), while digestion of DNA by restriction enzymes with subsequent ligation of the resulting DNA fragments continues to be the mainstream approach for generation of small- and medium-size plasmids. Rapid selection of a desired recombinant plasmid against a background of other plasmids continues to be a challenge. In this chapter, the emphasis is placed on efficient and flexible versions of DNA cloning protocols using selection of recombinant plasmids by restriction endonucleases directly in the ligation mixture.

  8. Production of lentiviral vectors

    PubMed Central

    Merten, Otto-Wilhelm; Hebben, Matthias; Bovolenta, Chiara

    2016-01-01

    Lentiviral vectors (LV) have seen considerably increase in use as gene therapy vectors for the treatment of acquired and inherited diseases. This review presents the state of the art of the production of these vectors with particular emphasis on their large-scale production for clinical purposes. In contrast to oncoretroviral vectors, which are produced using stable producer cell lines, clinical-grade LV are in most of the cases produced by transient transfection of 293 or 293T cells grown in cell factories. However, more recent developments, also, tend to use hollow fiber reactor, suspension culture processes, and the implementation of stable producer cell lines. As is customary for the biotech industry, rather sophisticated downstream processing protocols have been established to remove any undesirable process-derived contaminant, such as plasmid or host cell DNA or host cell proteins. This review compares published large-scale production and purification processes of LV and presents their process performances. Furthermore, developments in the domain of stable cell lines and their way to the use of production vehicles of clinical material will be presented. PMID:27110581

  9. Vectors Point Toward Pisa

    ERIC Educational Resources Information Center

    Dean, Richard A.

    1971-01-01

    The author shows that the set of all sequences in which each term is the sum of the two previous terms forms a vector space of dimension two. He uses this result to obtain the formula for the Fibonacci sequence and applies the same technique to other linear recursive relations. (MM)

  10. Support vector machines

    NASA Technical Reports Server (NTRS)

    Garay, Michael J.; Mazzoni, Dominic; Davies, Roger; Wagstaff, Kiri

    2004-01-01

    Support Vector Machines (SVMs) are a type of supervised learning algorith,, other examples of which are Artificial Neural Networks (ANNs), Decision Trees, and Naive Bayesian Classifiers. Supervised learning algorithms are used to classify objects labled by a 'supervisor' - typically a human 'expert.'.

  11. Killing vectors and anisotropy

    SciTech Connect

    Krisch, J. P.; Glass, E. N.

    2009-08-15

    We consider an action that can generate fluids with three unequal stresses for metrics with a spacelike Killing vector. The parameters in the action are directly related to the stress anisotropies. The field equations following from the action are applied to an anisotropic cosmological expansion and an extension of the Gott-Hiscock cosmic string.

  12. Singular Vectors' Subtle Secrets

    ERIC Educational Resources Information Center

    James, David; Lachance, Michael; Remski, Joan

    2011-01-01

    Social scientists use adjacency tables to discover influence networks within and among groups. Building on work by Moler and Morrison, we use ordered pairs from the components of the first and second singular vectors of adjacency matrices as tools to distinguish these groups and to identify particularly strong or weak individuals.

  13. Vector potential methods

    NASA Technical Reports Server (NTRS)

    Hafez, M.

    1989-01-01

    Vector potential and related methods, for the simulation of both inviscid and viscous flows over aerodynamic configurations, are briefly reviewed. The advantages and disadvantages of several formulations are discussed and alternate strategies are recommended. Scalar potential, modified potential, alternate formulations of Euler equations, least-squares formulation, variational principles, iterative techniques and related methods, and viscous flow simulation are discussed.

  14. Turbulence velocity profiling for high sensitivity and vertical-resolution atmospheric characterization with Stereo-SCIDAR

    NASA Astrophysics Data System (ADS)

    Osborn, J.; Butterley, T.; Townson, M. J.; Reeves, A. P.; Morris, T. J.; Wilson, R. W.

    2017-02-01

    As telescopes become larger, into the era of ˜40 m Extremely Large Telescopes, the high-resolution vertical profile of the optical turbulence strength is critical for the validation, optimization and operation of optical systems. The velocity of atmospheric optical turbulence is an important parameter for several applications including astronomical adaptive optics systems. Here, we compare the vertical profile of the velocity of the atmospheric wind above La Palma by means of a comparison of Stereo-SCIntillation Detection And Ranging (Stereo-SCIDAR) with the Global Forecast System models and nearby balloon-borne radiosondes. We use these data to validate the automated optical turbulence velocity identification from the Stereo-SCIDAR instrument mounted on the 2.5 m Isaac Newton Telescope, La Palma. By comparing these data we infer that the turbulence velocity and the wind velocity are consistent and that the automated turbulence velocity identification of the Stereo-SCIDAR is precise. The turbulence velocities can be used to increase the sensitivity of the turbulence strength profiles, as weaker turbulence that may be misinterpreted as noise can be detected with a velocity vector. The turbulence velocities can also be used to increase the altitude resolution of a detected layer, as the altitude of the velocity vectors can be identified to a greater precision than the native resolution of the system. We also show examples of complex velocity structure within a turbulent layer caused by wind shear at the interface of atmospheric zones.

  15. Exceptional Ground Accelerations and Velocities Caused by Earthquakes

    SciTech Connect

    Anderson, John

    2008-01-17

    This project aims to understand the characteristics of the free-field strong-motion records that have yielded the 100 largest peak accelerations and the 100 largest peak velocities recorded to date. The peak is defined as the maximum magnitude of the acceleration or velocity vector during the strong shaking. This compilation includes 35 records with peak acceleration greater than gravity, and 41 records with peak velocities greater than 100 cm/s. The results represent an estimated 150,000 instrument-years of strong-motion recordings. The mean horizontal acceleration or velocity, as used for the NGA ground motion models, is typically 0.76 times the magnitude of this vector peak. Accelerations in the top 100 come from earthquakes as small as magnitude 5, while velocities in the top 100 all come from earthquakes with magnitude 6 or larger. Records are dominated by crustal earthquakes with thrust, oblique-thrust, or strike-slip mechanisms. Normal faulting mechanisms in crustal earthquakes constitute under 5% of the records in the databases searched, and an even smaller percentage of the exceptional records. All NEHRP site categories have contributed exceptional records, in proportions similar to the extent that they are represented in the larger database.

  16. Velocity Distribution in the Boundary Layer of a Submerged Plate

    NASA Technical Reports Server (NTRS)

    Hansen, M

    1930-01-01

    This report deals with the measurement of the velocity distribution of the air in the velocity of a plate placed parallel to the air flow. The measurements took place in a small wind tunnel where the diameter of the entrance cone is 30 cm and the length of the free jet between the entrance and exit cones is about 2.5 m. The measurements were made in the free jet where the static pressure was constant, which was essential for the method of measurement used.

  17. Global traffic and disease vector dispersal.

    PubMed

    Tatem, Andrew J; Hay, Simon I; Rogers, David J

    2006-04-18

    The expansion of global air travel and seaborne trade overcomes geographic barriers to insect disease vectors, enabling them to move great distances in short periods of time. Here we apply a coupled human-environment framework to describe the historical spread of Aedes albopictus, a competent mosquito vector of 22 arboviruses in the laboratory. We contrast this dispersal with the relatively unchanged distribution of Anopheles gambiae and examine possible future movements of this malaria vector. We use a comprehensive database of international ship and aircraft traffic movements, combined with climatic information, to remap the global transportation network in terms of disease vector suitability and accessibility. The expansion of the range of Ae. albopictus proved to be surprisingly predictable using this combination of climate and traffic data. Traffic volumes were more than twice as high on shipping routes running from the historical distribution of Ae. albopictus to ports where it has established in comparison with routes to climatically similar ports where it has yet to invade. In contrast, An. gambiae has rarely spread from Africa, which we suggest is partly due to the low volume of sea traffic from the continent and, until very recently, a European destination for most flights.

  18. The SAMEX Vector Magnetograph: A Design Study for a Space-Based Solar Vector Magnetograph

    NASA Technical Reports Server (NTRS)

    Hagyard, M. J.; Gary, G. A.; West, E. A.

    1988-01-01

    This report presents the results of a pre-phase A study performed by the Marshall Space Flight Center (MSFC) for the Air Force Geophysics Laboratory (AFGL) to develop a design concept for a space-based solar vector magnetograph and hydrogen-alpha telescope. These are two of the core instruments for a proposed Air Force mission, the Solar Activities Measurement Experiments (SAMEX). This mission is designed to study the processes which give rise to activity in the solar atmosphere and to develop techniques for predicting solar activity and its effects on the terrestrial environment.

  19. Unitaxial constant velocity microactuator

    DOEpatents

    McIntyre, Timothy J.

    1994-01-01

    A uniaxial drive system or microactuator capable of operating in an ultra-high vacuum environment. The mechanism includes a flexible coupling having a bore therethrough, and two clamp/pusher assemblies mounted in axial ends of the coupling. The clamp/pusher assemblies are energized by voltage-operated piezoelectrics therewithin to operatively engage the shaft and coupling causing the shaft to move along its rotational axis through the bore. The microactuator is capable of repeatably positioning to sub-manometer accuracy while affording a scan range in excess of 5 centimeters. Moreover, the microactuator generates smooth, constant velocity motion profiles while producing a drive thrust of greater than 10 pounds. The system is remotely controlled and piezoelectrically driven, hence minimal thermal loading, vibrational excitation, or outgassing is introduced to the operating environment.

  20. Unitaxial constant velocity microactuator

    DOEpatents

    McIntyre, T.J.

    1994-06-07

    A uniaxial drive system or microactuator capable of operating in an ultra-high vacuum environment is disclosed. The mechanism includes a flexible coupling having a bore therethrough, and two clamp/pusher assemblies mounted in axial ends of the coupling. The clamp/pusher assemblies are energized by voltage-operated piezoelectrics therewithin to operatively engage the shaft and coupling causing the shaft to move along its rotational axis through the bore. The microactuator is capable of repeatably positioning to sub-nanometer accuracy while affording a scan range in excess of 5 centimeters. Moreover, the microactuator generates smooth, constant velocity motion profiles while producing a drive thrust of greater than 10 pounds. The system is remotely controlled and piezoelectrically driven, hence minimal thermal loading, vibrational excitation, or outgassing is introduced to the operating environment. 10 figs.

  1. Analyzing angular distributions for two-step dissociation mechanisms in velocity map imaging.

    PubMed

    Straus, Daniel B; Butler, Lynne M; Alligood, Bridget W; Butler, Laurie J

    2013-08-15

    Increasingly, velocity map imaging is becoming the method of choice to study photoinduced molecular dissociation processes. This paper introduces an algorithm to analyze the measured net speed, P(vnet), and angular, β(vnet), distributions of the products from a two-step dissociation mechanism, where the first step but not the second is induced by absorption of linearly polarized laser light. Typically, this might be the photodissociation of a C-X bond (X = halogen or other atom) to produce an atom and a momentum-matched radical that has enough internal energy to subsequently dissociate (without the absorption of an additional photon). It is this second step, the dissociation of the unstable radicals, that one wishes to study, but the measured net velocity of the final products is the vector sum of the velocity imparted to the radical in the primary photodissociation (which is determined by taking data on the momentum-matched atomic cophotofragment) and the additional velocity vector imparted in the subsequent dissociation of the unstable radical. The algorithm allows one to determine, from the forward-convolution fitting of the net velocity distribution, the distribution of velocity vectors imparted in the second step of the mechanism. One can thus deduce the secondary velocity distribution, characterized by a speed distribution P(v1,2°) and an angular distribution I(θ2°), where θ2° is the angle between the dissociating radical's velocity vector and the additional velocity vector imparted to the product detected from the subsequent dissociation of the radical.

  2. Doppler Lidar Vertical Velocity Statistics Value-Added Product

    SciTech Connect

    Newsom, R. K.; Sivaraman, C.; Shippert, T. R.; Riihimaki, L. D.

    2015-07-01

    Accurate height-resolved measurements of higher-order statistical moments of vertical velocity fluctuations are crucial for improved understanding of turbulent mixing and diffusion, convective initiation, and cloud life cycles. The Atmospheric Radiation Measurement (ARM) Climate Research Facility operates coherent Doppler lidar systems at several sites around the globe. These instruments provide measurements of clear-air vertical velocity profiles in the lower troposphere with a nominal temporal resolution of 1 sec and height resolution of 30 m. The purpose of the Doppler lidar vertical velocity statistics (DLWSTATS) value-added product (VAP) is to produce height- and time-resolved estimates of vertical velocity variance, skewness, and kurtosis from these raw measurements. The VAP also produces estimates of cloud properties, including cloud-base height (CBH), cloud frequency, cloud-base vertical velocity, and cloud-base updraft fraction.

  3. Seasonal changes in the apparent position of the Sun as elementary applications of vector operations

    NASA Astrophysics Data System (ADS)

    Levine, Jonathan

    2014-11-01

    Many introductory courses in physics face an unpleasant chicken-and-egg problem. One might choose to introduce students to physical quantities such as velocity, acceleration, and momentum in over-simplified one-dimensional applications before introducing vectors and their manipulation; or one might first introduce vectors as mathematical objects and defer demonstration of their physical utility. This paper offers a solution to this pedagogical problem: elementary vector operations can be used without mechanics concepts to understand variations in the solar latitude, duration of daylight, and orientation of the rising and setting Sun. I show how sunrise and sunset phenomena lend themselves to exercises with scalar products, vector products, unit vectors, and vector projections that can be useful for introducing vector analysis in the context of physics.

  4. Visual control of walking velocity.

    PubMed

    François, Matthieu; Morice, Antoine H P; Bootsma, Reinoud J; Montagne, Gilles

    2011-06-01

    Even if optical correlates of self-motion velocity have already been identified, their contribution to the control of displacement velocity remains to be established. In this study, we used a virtual reality set-up coupled to a treadmill to test the role of both Global Optic Flow Rate (GOFR) and Edge Rate (ER) in the regulation of walking velocity. Participants were required to walk at a constant velocity, corresponding to their preferred walking velocity, while eye height and texture density were manipulated. This manipulation perturbed the natural relationship between the actual walking velocity and its optical specification by GOFR and ER, respectively. Results revealed that both these sources of information are indeed used by participants to control walking speed, as demonstrated by a slowing down of actual walking velocity when the optical specification of velocity by either GOFR or ER gives rise to an overestimation of actual velocity, and vice versa. Gait analyses showed that these walking velocity adjustments result from simultaneous adaptations in both step length and step duration. The role of visual information in the control of self-motion velocity is discussed in relation with other factors.

  5. Auditory Risk of Air Rifles

    PubMed Central

    Lankford, James E.; Meinke, Deanna K.; Flamme, Gregory A.; Finan, Donald S.; Stewart, Michael; Tasko, Stephen; Murphy, William J.

    2016-01-01

    Objective To characterize the impulse noise exposure and auditory risk for air rifle users for both youth and adults. Design Acoustic characteristics were examined and the auditory risk estimates were evaluated using contemporary damage-risk criteria for unprotected adult listeners and the 120-dB peak limit and LAeq75 exposure limit suggested by the World Health Organization (1999) for children. Study sample Impulses were generated by 9 pellet air rifles and 1 BB air rifle. Results None of the air rifles generated peak levels that exceeded the 140 dB peak limit for adults and 8 (80%) exceeded the 120 dB peak SPL limit for youth. In general, for both adults and youth there is minimal auditory risk when shooting less than 100 unprotected shots with pellet air rifles. Air rifles with suppressors were less hazardous than those without suppressors and the pellet air rifles with higher velocities were generally more hazardous than those with lower velocities. Conclusion To minimize auditory risk, youth should utilize air rifles with an integrated suppressor and lower velocity ratings. Air rifle shooters are advised to wear hearing protection whenever engaging in shooting activities in order to gain self-efficacy and model appropriate hearing health behaviors necessary for recreational firearm use. PMID:26840923

  6. Mixing of relativistic ideal gases with relative relativistic velocities

    NASA Astrophysics Data System (ADS)

    Gonzalez-Narvaez, R. E.; Ares de Parga, A. M.; Ares de Parga, G.

    2017-01-01

    The Redefined Relativistic Thermodynamics is tested by means of mixing two ideal gases at different temperatures and distinct velocities. The conservation of the 4-vector energy-momentum leads to a tremendous increment of the temperature. This phenomenon can be used in order to describe the heating of a cold clump with shocked jets material. A prediction for improving the ignition of a Tokamak is proposed. The compatibility of the Redefined Relativistic Thermodynamics with the Thermodynamical Field Theory is analyzed.

  7. Correlation of bubble rise velocity and volume

    SciTech Connect

    Burge, C.

    1991-01-01

    This project was conducted at Westinghouse's Savannah River Laboratories (SRL). The goal of SRL is to make certain that the modifications on the reactor are safe for those working at the plant as well as the general public. One of the steps needed to insure safety is the knowledge of the occurrences that result from a plenum pipe breakage. When a plenum pipe breaks, two things occur: air is sucked into the pipe and is trapped in the cooling water; and water used to cool the fuel rods is lost. As a result of these occurrences, the water is slowed down by both the loss in water pressure and the upward force of air bubbles pushing against the downward force of the water. The project required the conducting of tests to find the bubble velocity in an annular ribbed pipe filled with stagnant water. This document discusses the methodology and results of this testing.

  8. Correlation of bubble rise velocity and volume

    SciTech Connect

    Burge, C.

    1991-12-31

    This project was conducted at Westinghouse`s Savannah River Laboratories (SRL). The goal of SRL is to make certain that the modifications on the reactor are safe for those working at the plant as well as the general public. One of the steps needed to insure safety is the knowledge of the occurrences that result from a plenum pipe breakage. When a plenum pipe breaks, two things occur: air is sucked into the pipe and is trapped in the cooling water; and water used to cool the fuel rods is lost. As a result of these occurrences, the water is slowed down by both the loss in water pressure and the upward force of air bubbles pushing against the downward force of the water. The project required the conducting of tests to find the bubble velocity in an annular ribbed pipe filled with stagnant water. This document discusses the methodology and results of this testing.

  9. Flight management concepts compatible with air traffic control

    NASA Technical Reports Server (NTRS)

    Morello, S. A.

    1986-01-01

    With the advent of airline deregulation and increased competition, the need for cost efficient airline operations is critical. This paper summarizes past research efforts and planned research thrusts toward the development of compatible flight management and air traffic control systems that promise increased operational effectiveness and efficiency. Potential capacity improvements resulting from a time-based ATC simulation (fast-time) are presented. Advanced display concepts with time guidance and velocity vector information to allow the flight crew to play an important role in the future ATC environment are discussed. Results of parametric sensitivity analyses are also presented that quantify the fuel/cost penalties for idle-thrust mismodeling and wind-modeling errors.

  10. Global velocity constrained cloud motion prediction for short-term solar forecasting

    NASA Astrophysics Data System (ADS)

    Chen, Yanjun; Li, Wei; Zhang, Chongyang; Hu, Chuanping

    2016-09-01

    Cloud motion is the primary reason for short-term solar power output fluctuation. In this work, a new cloud motion estimation algorithm using a global velocity constraint is proposed. Compared to the most used Particle Image Velocity (PIV) algorithm, which assumes the homogeneity of motion vectors, the proposed method can capture the accurate motion vector for each cloud block, including both the motional tendency and morphological changes. Specifically, global velocity derived from PIV is first calculated, and then fine-grained cloud motion estimation can be achieved by global velocity based cloud block researching and multi-scale cloud block matching. Experimental results show that the proposed global velocity constrained cloud motion prediction achieves comparable performance to the existing PIV and filtered PIV algorithms, especially in a short prediction horizon.

  11. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  12. Velocity and drop size measurements in a swirl-stabilized, combusting spray

    NASA Technical Reports Server (NTRS)

    Bulzan, Daniel L.

    1993-01-01

    Velocity and drop size measurements are reported for a swirl-stabilized, combusting spray. For the gas phase, three components of mean and fluctuating velocity are reported. For the droplets, three components of mean and fluctuating velocity, diameter, and number flux are reported. The liquid fuel utilized for all the tests was heptane. The fuel was injected using an air-assist atomizer. The combustor configuration consisted of a center-mounted, air-assist atomizer surrounded by a coflowing air stream. Both the coflow and the atomizing air streams were passed through 45 degree swirlers. The swirl was imparted to both streams in the same direction. The combustion occurred unconfined in stagnant surroundings. The nonintrusive measurements were obtained using a two-component phase/Doppler particle analyzer. The laser-based instrument measured two components of velocity as well as droplet size at a particular point. Gas phase measurements were obtained by seeding the air streams with nominal 1 micron size aluminum-oxide particles and using the measured velocity from that size to represent the gas phase velocity. The atomizing air, coflow air, and ambient surroundings were all seeded with the aluminum-oxide particles to prevent biasing. Measurements are reported at an axial distance of 5 mm from the nozzle. Isothermal single-phase gas velocities are also reported for comparison with the combusting case.

  13. Vector fields in cosmology

    NASA Astrophysics Data System (ADS)

    Davydov, E. A.

    2012-06-01

    Vector fields can arise in the cosmological context in different ways, and we discuss both abelian and nonabelian sector. In the abelian sector vector fields of the geometrical origin (from dimensional reduction and Einstein-Eddington modification of gravity) can provide a very non-trivial dynamics, which can be expressed in terms of the effective dilaton-scalar gravity with the specific potential. In the non-abelian sector we investigate the Yang-Mills SU(2) theory which admits isotropic and homogeneous configuration. Provided the non-linear dependence of the lagrangian on the invariant FμνF~μν, one can obtain the inflationary regime with the exponential growth of the scale factor. The effective amplitudes of the `electric' and `magnetic' components behave like slowly varying scalars at this regime, what allows the consideration of some realistic models with non-linear terms in the Yang-Mills lagrangian.

  14. Vector Magnetograph Design

    NASA Technical Reports Server (NTRS)

    Chipman, Russell A.

    1996-01-01

    This report covers work performed during the period of November 1994 through March 1996 on the design of a Space-borne Solar Vector Magnetograph. This work has been performed as part of a design team under the supervision of Dr. Mona Hagyard and Dr. Alan Gary of the Space Science Laboratory. Many tasks were performed and this report documents the results from some of those tasks, each contained in the corresponding appendix. Appendices are organized in chronological order.

  15. Some experiences with Krylov vectors and Lanczos vectors

    NASA Technical Reports Server (NTRS)

    Craig, Roy R., Jr.; Su, Tzu-Jeng; Kim, Hyoung M.

    1993-01-01

    This paper illustrates the use of Krylov vectors and Lanczos vectors for reduced-order modeling in structural dynamics and for control of flexible structures. Krylov vectors and Lanczos vectors are defined and illustrated, and several applications that have been under study at The University of Texas at Austin are reviewed: model reduction for undamped structural dynamics systems, component mode synthesis using Krylov vectors, model reduction of damped structural dynamics systems, and one-sided and two-sided unsymmetric block-Lanczos model-reduction algorithms.

  16. Isomap based supporting vector machine

    NASA Astrophysics Data System (ADS)

    Liang, W. N.

    2015-12-01

    This research presents a new isomap based supporting vector machine method. Isomap is a dimension reduction method which is able to analyze nonlinear relationship of data on manifolds. Accordingly, support vector machine is established on the isomap manifold to classify given and predict unknown data. A case study of the isomap based supporting vector machine for environmental planning problems is conducted.

  17. What is a vector?

    PubMed Central

    Morgan, Eric René; Booth, Mark; Norman, Rachel; Mideo, Nicole; McCallum, Hamish; Fenton, Andy

    2017-01-01

    Many important and rapidly emerging pathogens of humans, livestock and wildlife are ‘vector-borne’. However, the term ‘vector’ has been applied to diverse agents in a broad range of epidemiological systems. In this perspective, we briefly review some common definitions, identify the strengths and weaknesses of each and consider the functional differences between vectors and other hosts from a range of ecological, evolutionary and public health perspectives. We then consider how the use of designations can afford insights into our understanding of epidemiological and evolutionary processes that are not otherwise apparent. We conclude that from a medical and veterinary perspective, a combination of the ‘haematophagous arthropod’ and ‘mobility’ definitions is most useful because it offers important insights into contact structure and control and emphasizes the opportunities for pathogen shifts among taxonomically similar species with similar feeding modes and internal environments. From a population dynamics and evolutionary perspective, we suggest that a combination of the ‘micropredator’ and ‘sequential’ definition is most appropriate because it captures the key aspects of transmission biology and fitness consequences for the pathogen and vector itself. However, we explicitly recognize that the value of a definition always depends on the research question under study. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’. PMID:28289253

  18. The Relativistic Wave Vector

    ERIC Educational Resources Information Center

    Houlrik, Jens Madsen

    2009-01-01

    The Lorentz transformation applies directly to the kinematics of moving particles viewed as geometric points. Wave propagation, on the other hand, involves moving planes which are extended objects defined by simultaneity. By treating a plane wave as a geometric object moving at the phase velocity, novel results are obtained that illustrate the…

  19. Vector Helmholtz-Gauss and vector Laplace-Gauss beams.

    PubMed

    Bandres, Miguel A; Gutiérrez-Vega, Julio C

    2005-08-15

    We demonstrate the existence of vector Helmholtz-Gauss (vHzG) and vector Laplace-Gauss beams that constitute two general families of localized vector beam solutions of the Maxwell equations in the paraxial approximation. The electromagnetic components are determined starting from the scalar solutions of the two-dimensional Helmholtz and Laplace equations, respectively. Special cases of the vHzG beams are TE and TM Gaussian vector beams, nondiffracting vector Bessel beams, polarized Bessel-Gauss beams, modes in cylindrical waveguides and cavities, and scalar Helmholtz-Gauss beams. The general expression of the vHzG beams can be used straightforwardly to obtain vector Mathieu-Gauss and vector parabolic-Gauss beams, which to our knowledge have not yet been reported.

  20. Spacecraft attitude and velocity control system

    NASA Technical Reports Server (NTRS)

    Paluszek, Michael A. (Inventor); Piper, Jr., George E. (Inventor)

    1992-01-01

    A spacecraft attitude and/or velocity control system includes a controller which responds to at least attitude errors to produce command signals representing a force vector F and a torque vector T, each having three orthogonal components, which represent the forces and torques which are to be generated by the thrusters. The thrusters may include magnetic torquer or reaction wheels. Six difference equations are generated, three having the form ##EQU1## where a.sub.j is the maximum torque which the j.sup.th thruster can produce, b.sub.j is the maximum force which the j.sup.th thruster can produce, and .alpha..sub.j is a variable representing the throttling factor of the j.sup.th thruster, which may range from zero to unity. The six equations are summed to produce a single scalar equation relating variables .alpha..sub.j to a performance index Z: ##EQU2## Those values of .alpha. which maximize the value of Z are determined by a method for solving linear equations, such as a linear programming method. The Simplex method may be used. The values of .alpha..sub.j are applied to control the corresponding thrusters.

  1. The Connection between Inertial Forces and the Vector Potential

    NASA Astrophysics Data System (ADS)

    Martins, Alexandre A.; Pinheiro, Mario J.

    2007-01-01

    The inertia property of matter is discussed in terms of a type of induction law related to the extended charged particle's own vector potential. Our approach is based on the Lagrangian formalism of canonical momentum writing Newton's second law in terms of the vector potential and a development in terms of obtaining retarded potentials, that allow an intuitive physical interpretation of its main terms. This framework provides a clear physical insight on the physics of inertia. It is shown that the electron mass has a complete electromagnetic origin and the covariant equation obtained solves the "4/3 mass paradox". This provides a deeper insight into the significance of the main terms of the equation of motion. In particular a force term is obtained from the approach based on the continuity equation for momentum that represents a drag force the charged particle feels when in motion relatively to its own vector potential field lines. Thus, the time derivative of the particle's vector potential leads to the acceleration inertia reaction force and is equivalent to the Schott term responsible for the source of the radiation field. We also show that the velocity dependent term of the particle's vector potential is connected with the relativistic increase of mass with velocity and generates a stress force that is the source of electric field lines deformation. This understanding broadens the possibility to manipulate inertial mass and potentially suggests some mechanisms for possible applications to electromagnetic propulsion and the development of advanced space propulsion physics.

  2. Factors influencing perceived angular velocity

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary K.; Calderone, Jack B.

    1991-01-01

    Angular velocity perception is examined for rotations both in depth and in the image plane and the influence of several object properties on this motion parameter is explored. Two major object properties are considered, namely, texture density which determines the rate of edge transitions for rotations in depth, i.e., the number of texture elements that pass an object's boundary per unit of time, and object size which determines the tangential linear velocities and 2D image velocities of texture elements for a given angular velocity. Results of experiments show that edge-transition rate biased angular velocity estimates only when edges were highly salient. Element velocities had an impact on perceived angular velocity; this bias was associated with 2D image velocity rather than 3D tangential velocity. Despite these biases judgements were most strongly determined by the true angular velocity. Sensitivity to this higher order motion parameter appeared to be good for rotations both in depth (y-axis) and parallel to the line of sight (z-axis).

  3. Hydrokinetic canal measurements: inflow velocity, wake flow velocity, and turbulence

    SciTech Connect

    Gunawan, Budi

    2014-06-11

    The dataset consist of acoustic Doppler current profiler (ADCP) velocity measurements in the wake of a 3-meter diameter vertical-axis hydrokinetic turbine deployed in Roza Canal, Yakima, WA, USA. A normalized hub-centerline wake velocity profile and two cross-section velocity contours, 10 meters and 20 meters downstream of the turbine, are presented. Mean velocities and turbulence data, measured using acoustic Doppler velocimeter (ADV) at 50 meters upstream of the turbine, are also presented. Canal dimensions and hydraulic properties, and turbine-related information are also included.

  4. Velocity dependant splash behaviour

    NASA Astrophysics Data System (ADS)

    Hamlett, C. A. E.; Shirtcliffe, N. J.; McHale, G.; Ahn, S.; Doerr, S. H.; Bryant, R.; Newton, M. I.

    2012-04-01

    Extreme soil water repellency can occur in nature via condensation of volatile organic compounds released during wildfires and can lead to increased erosion rate. Such extreme water repellent soil can be classified as superhydrophobic and shares similar chemical and topographical features to specifically designed superhydrophobic surfaces. Previous studies using high speed videography to investigate single droplet impact behaviour on artificial superhydrophobic have revealed three distinct modes of splash behaviour (rebound, pinned and fragmentation) which are dependent on the impact velocity of the droplet. In our studies, using high-speed videography, we show that such splash behaviour can be replicated on fixed 'model' water repellent soils (hydrophobic glass beads/particles). We show that the type of splash behaviour is dependent on both the size and chemical nature of the fixed particles. The particle shape also influences the splash behaviour as shown by drop impact experiments on fixed sand samples. We have also studied soil samples, as collected from the field, which shows that the type of droplet splash behaviour can lead to enhanced soil particle transport.

  5. Particle Velocity Measuring System

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Carl, James R. (Inventor)

    1998-01-01

    Method and apparatus are provided for determining the velocity of individual food particles within a liquid/solid food mixture that is cooked by an aseptic cooking method whereby the food mixture is heated as it flows through a flowline. At least one upstream and at least one downstream microwave transducer are provided to determine the minimum possible travel time of the fastest food particle through the flowline. In one embodiment, the upstream detector is not required. In another embodiment, a plurality of small dipole antenna markers are secured to a plurality of food particles to provide a plurality of signals as the markers pass the upstream and downstream transducers. The dipole antenna markers may also include a non-linear element to reradiate a harmonic frequency of a transmitter frequency. Upstream and downstream transducers include dipole antennas that are matched to the impedance of the food slurry and a signal transmission cable by various impedance matching means including unbalanced feed to the antennas.

  6. The construction and use of divergence free vector expansions for incompressible fluid flow calculations

    NASA Technical Reports Server (NTRS)

    Mhuiris, N. M. G.

    1986-01-01

    For incompressible fluids the law of mass conservation reduces to a constraint on the velocity vector, namely that it be divergence free. This constraint has long been a source of great difficulty to the numericist seeking to discretize the Navier-Stokes and Euler equations. A spectral method is discussed which overcomes this difficulty. Its efficacy is demonstrated on some simple problems. The velocity is approximated by a finite sum of divergence free vectors, each of which satisfies the same boundary conditions as the velocity. Projecting the governing equation onto the space of inviscid vector fields eliminates the pressure term and produces a set of ordinary differential equations that must be solved for the coefficents in the velocity. The pressure can then be recovered if it is needed.

  7. Monte-Carlo Method Application for Precising Meteor Velocity from TV Observations

    NASA Astrophysics Data System (ADS)

    Kozak, P.

    2014-12-01

    Monte-Carlo method (method of statistical trials) as an application for meteor observations processing was developed in author's Ph.D. thesis in 2005 and first used in his works in 2008. The idea of using the method consists in that if we generate random values of input data – equatorial coordinates of the meteor head in a sequence of TV frames – in accordance with their statistical distributions we get a possibility to plot the probability density distributions for all its kinematical parameters, and to obtain their mean values and dispersions. At that the theoretical possibility appears to precise the most important parameter – geocentric velocity of a meteor – which has the highest influence onto precision of meteor heliocentric orbit elements calculation. In classical approach the velocity vector was calculated in two stages: first we calculate the vector direction as a vector multiplication of vectors of poles of meteor trajectory big circles, calculated from two observational points. Then we calculated the absolute value of velocity independently from each observational point selecting any of them from some reasons as a final parameter. In the given method we propose to obtain a statistical distribution of velocity absolute value as an intersection of two distributions corresponding to velocity values obtained from different points. We suppose that such an approach has to substantially increase the precision of meteor velocity calculation and remove any subjective inaccuracies.

  8. Tracking Vector Magnetograms with the Magnetic Induction Equation

    NASA Technical Reports Server (NTRS)

    Schuck, P.

    2009-01-01

    The differential affine velocity estimator (DAVE) that we developed in 2006 for estimating velocities from line-of-sight magnetograms is modified to directly incorporate horizontal magnetic fields to produce a differential affine velocity estimator for vector magnetograms (DAVE4VM). The DAVE4VM's performance is demonstrated on the synthetic data from the anelastic pseudospectral ANMHD simulations that were used in the recent comparison of velocity inversion techniques by Welsch and coworkers. The DAVE4VM predicts roughly 95% of the helicity rate and 75% of the power transmitted through the simulation slice. Intercomparison between DAVE4VM and DAVE and further analysis of the DAVE method demonstrates that line-of-sight tracking methods capture the shearing motion of magnetic footpoints but are insensitive to flux emergence - the velocities determined from line-of-sight methods are more consistent with horizontal plasma velocities than with flux transport velocities. These results suggest that previous studies that rely on velocities determined from line-of-sight methods such as the DAVE or local correlation tracking may substantially misrepresent the total helicity rates and power through the photosphere.

  9. Vector representation of tourmaline compositions

    NASA Technical Reports Server (NTRS)

    Burt, Donald M.

    1989-01-01

    The vector method for representing mineral compositions of amphibole and mica groups is applied to the tourmaline group. Consideration is given to the methods for drawing the relevant vector diagrams, relating the exchange vectors to one another, and contouring the diagrams for constant values of Na, Ca, Li, Fe, Mg, Al, Si, and OH. The method is used to depict a wide range of possible tourmaline end-member compositions and solid solutions, starting from a single point. In addition to vector depictions of multicomponent natural tourmalines, vectors are presented for simpler systems such as (Na,Al)-tourmalines, alkali-free tourmalines, and elbaites.

  10. Vector Correlation in the Photodissociation of Metal Nitrosyls

    NASA Astrophysics Data System (ADS)

    Bartz, Jeffrey A.; Peden, Amber L.; Kieda, Ryan D.

    2010-06-01

    The vector correlation in the photodissociation of metal nitrosyls has been determined using linearly-polarized laser light and velocity-mapped ion imaging. The 225-nm dissociation beam excites a doubly-degenerate metal-to-ligand charge transfer in both eta5-C5H5NiNO and Co(CO)3NO. State-resolved detection of the NO product through the A (v'=0) ← X (v"=0) transition reveals that both molecules dissociate promptly with a high degree of vector correlation.

  11. Concentration and Velocity Gradients in Fluidized Beds

    NASA Technical Reports Server (NTRS)

    McClymer, James P.

    2003-01-01

    In this work we focus on the height dependence of particle concentration, average velocity components, fluctuations in these velocities and, with the flow turned off, the sedimentation velocity. The latter quantities are measured using Particle Imaging Velocimetry (PIV). The PIV technique uses a 1-megapixel camera to capture two time-displaced images of particles in the bed. The depth of field of the imaging system is approximately 0.5 cm. The camera images a region with characteristic length of 2.6 cm for the small particles and 4.7 cm. for the large particles. The local direction of particle flow is determined by calculating the correlation function for sub-regions of 32 x 32 pixels. The velocity vector map is created from this correlation function using the time between images (we use 15 to 30 ms). The software is sensitive variations of 1/64th of a pixel. We produce velocity maps at various heights, each consisting of 3844 velocities. We break this map into three vertical zones for increased height information. The concentration profile is measured using an expanded (1 cm diameter) linearly polarized HeNe Laser incident on the fluidized bed. A COHU camera (gamma=1, AGC off) with a lens and a polarizer images the transmitted linearly polarized light to minimize the effects of multiply scattered light. The intensity profile (640 X 480 pixels) is well described by a Gaussian fit and the height of the Gaussian is used to characterize the concentration. This value is compared to the heights found for known concentrations. The sedimentation velocity is estimated using by imaging a region near the bottom of the bed and using PIV to measure the velocity as a function of time. With a nearly uniform concentration profile, the time can be converted to height information. The stable fluidized beds are made from large pseudo-monodisperse particles (silica spheres with radii (250-300) microns and (425-500) microns) dispersed in a glycerin/water mix. The Peclet number is

  12. Estimation of Laminar Burning Velocities by Direct Digital Photography

    ERIC Educational Resources Information Center

    Uske, J.; Barat, R.

    2004-01-01

    The Bunsen burner flame, which is the most common flame in the laboratory, can be easily studied for its dynamics because of modern, economical digital technology available to student laboratories. Direct digital photography of Bunsen flames is used to obtain laminar burning velocities of selected gaseous hydrocarbon/air flames.

  13. Pneumatic Conveying of Seed Cotton: Minimum Velocity and Pressure Drop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electricity is a major cost for cotton gins, representing approximately 20% of variable costs. Fans used for pneumatic conveying consume the majority of electricity at cotton gins. Development of control systems to reduce the air velocity used for conveying seed cotton could significantly decrease e...

  14. Pneumatic Conveying of Seed Cotton: Minimum Velocity and Pressure Drop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electricity is major cost for cotton gins, representing approximately 20% of the industry’s variable costs. Fans used for pneumatic conveying consume the majority of electricity at cotton gins. Development of control systems to reduce the air velocity used for conveying seed cotton could significant...

  15. Supply Chain Synchronization: Improving Distribution Velocity to the Theatre

    DTIC Science & Technology

    2009-06-01

    additional research available if the breadth of the search was expanded to include SCM principles as applied to weapons 15 systems procurement other...SYNCHRONIZATION: IMPROVING DISTRIBUTION VELOCITY TO THE THEATRE GRADUATE RESEARCH PROJECT Presented to the Faculty Department of Systems ...Using archived data from command, control, and planning systems , 1257 pallets were tracked from Dover Air Force Base (AFB), Delaware to various APODs

  16. Similarity of the Velocity Profile

    DTIC Science & Technology

    2014-10-01

    su x (with 0 constantb = ) is the empirically derived velocity scale developed by Zagarola and Smits [5] for turbulent boundary layer flow...Zagarola and Smits and others have shown that the velocity scaling factor given by Eq. 5 with sδ as the boundary layer thickness can collapse certain...and Smits , it is important to point out that the fact that the similarity length scale factor and the similarity velocity scale factor must follow

  17. Vector ecology of equine piroplasmosis.

    PubMed

    Scoles, Glen A; Ueti, Massaro W

    2015-01-07

    Equine piroplasmosis is a disease of Equidae, including horses, donkeys, mules, and zebras, caused by either of two protozoan parasites, Theileria equi or Babesia caballi. These parasites are biologically transmitted between hosts via tick vectors, and although they have inherent differences they are categorized together because they cause similar pathology and have similar morphologies, life cycles, and vector relationships. To complete their life cycle, these parasites must undergo a complex series of developmental events, including sexual-stage development in their tick vectors. Consequently, ticks are the definitive hosts as well as vectors for these parasites, and the vector relationship is restricted to a few competent tick species. Because the vector relationship is critical to the epidemiology of these parasites, we highlight current knowledge of the vector ecology of these tick-borne equine pathogens, emphasizing tick transmissibility and potential control strategies to prevent their spread.

  18. Velocity Dispersions Across Bulge Types

    SciTech Connect

    Fabricius, Maximilian; Bender, Ralf; Hopp, Ulrich; Saglia, Roberto; Drory, Niv; Fisher, David

    2010-06-08

    We present first results from a long-slit spectroscopic survey of bulge kinematics in local spiral galaxies. Our optical spectra were obtained at the Hobby-Eberly Telescope with the LRS spectrograph and have a velocity resolution of 45 km/s (sigma*), which allows us to resolve the velocity dispersions in the bulge regions of most objects in our sample. We find that the velocity dispersion profiles in morphological classical bulge galaxies are always centrally peaked while the velocity dispersion of morphologically disk-like bulges stays relatively flat towards the center--once strongly barred galaxies are discarded.

  19. Bubbly flow velocity measurements near a heated cylindrical conductor

    SciTech Connect

    Canaan, R.E.; Hassan, Y.A. )

    1990-01-01

    The objective of this study is to apply recent advances and improvements in the digital pulsed laser velocimetry (DPLV) technique to the analysis of two-phase bubbly flow about a cylindrical conductor emitting a constant heat flux within a transparent rectangular enclosure. Pulsed laser velocimetry is a rapidly advancing fluid flow visualization technique that determines full-field instantaneous velocity vectors of a quantitative nature such that the flow field remains undisturbed by the measurement. The DPLV method offers several significant advantages over more traditional fluid velocity measurement techniques such as hot wire/film anemometry and laser Doppler anemometry because reliable instantaneous velocity data may be acquired over substantial flow areas in a single experiment.

  20. Tests and Comparisons of Velocity-Inversion Techniques

    NASA Astrophysics Data System (ADS)

    Welsch, B. T.; Abbett, W. P.; De Rosa, M. L.; Fisher, G. H.; Georgoulis, M. K.; Kusano, K.; Longcope, D. W.; Ravindra, B.; Schuck, P. W.

    2007-12-01

    Recently, several methods that measure the velocity of magnetized plasma from time series of photospheric vector magnetograms have been developed. Velocity fields derived using such techniques can be used both to determine the fluxes of magnetic energy and helicity into the corona, which have important consequences for understanding solar flares, coronal mass ejections, and the solar dynamo, and to drive time-dependent numerical models of coronal magnetic fields. To date, these methods have not been rigorously tested against realistic, simulated data sets, in which the magnetic field evolution and velocities are known. Here we present the results of such tests using several velocity-inversion techniques applied to synthetic magnetogram data sets, generated from anelastic MHD simulations of the upper convection zone with the ANMHD code, in which the velocity field is fully known. Broadly speaking, the MEF, DAVE, FLCT, IM, and ILCT algorithms performed comparably in many categories. While DAVE estimated the magnitude and direction of velocities slightly more accurately than the other methods, MEF's estimates of the fluxes of magnetic energy and helicity were far more accurate than any other method's. Overall, therefore, the MEF algorithm performed best in tests using the ANMHD data set. We note that ANMHD data simulate fully relaxed convection in a high-β plasma, and therefore do not realistically model photospheric evolution.

  1. Velocity profiles between two baffles in a horizontal circular tube

    NASA Astrophysics Data System (ADS)

    Chang, Tae-Hyun; Lee, Hae-Soo; Oh, Keon-Je; Doh, Doeg Hee; Lee, Chang-Hoan

    2014-12-01

    The shell and tube heat exchanger is an essential part of a power plant for recovering heat transfer between the feed water of a boiler and the wasted heat. The baffles are also an important element inside the heat exchanger. Internal materials influence the flow pattern in the bed. The influence of baffles in the velocity profiles was observed using a three-dimensional particle image velocimetry around baffles in a horizontal circular tube. The velocity of the particles was measured before the baffle and between them in the test tube. Results show that the flows near the front baffle flow were parallel to the vertical wall, and then concentrate on the upper opening of the front baffle. The flows circulate in the front and rear baffles. These flow profiles are related to the Reynolds number (Re) or the flow intensity. The velocity profiles at lower Re number showed a complicated mixing, concentrating on the lower opening of the rear baffle as front wall. Swirling flow was employed in this study, which was produced using tangential velocities at the inlet. At the entrance of the front baffle, the velocity vector profiles with swirl were much different from that without swirl. However, velocities between two baffles are not much different from those without swirl.

  2. Anomalous sound velocity in multiferroic BiFeO3

    NASA Astrophysics Data System (ADS)

    Cao, Xian-Sheng; Ji, Gao-Feng; Jiang, Xing-Fang

    2016-11-01

    The sound velocity in multiferroic BiFeO3 (BFO) is studied with using Green's function technology on the basis of the magnetoelectric coupling, the spin-phonon interaction and the anharmonic phonon-phonon interaction. The Heisenberg-like model is employed to describe the magnetic subsystem, and the transverse Ising model is used to explain the ferroelectric subsystem. The reduced velocity is obtained in the limit of zero wave vectors. It is shown that the reduced velocity of sound in BiFeO3 exhibits a kink at the magnetic phase transition temperature TN. This anomaly in reduced velocity can be explained as an influence of vanishing magnetic ordering above TN and the ferroelectric subsystem can not be influenced by the magnetic subsystem above TN due to TN≪TC in the BFO. It is shown that the influence of the RM is only below TN in the phase where ferroelectric and magnetic properties exist together, whereas the RE influences the properties of the reduced velocity in the whole temperature region (Tvelocities decrease with increasing temperature. The achieved conclusion is in accordance with the experimental results.

  3. Vector potential photoelectron microscopy.

    PubMed

    Browning, R

    2011-10-01

    A new class of electron microscope has been developed for the chemical microanalysis of a wide range of real world samples using photoelectron spectroscopy. Highly structured, three-dimensional samples, such as fiber mats and fracture surfaces can be imaged, as well as insulators and magnetic materials. The new microscope uses the vector potential field from a solenoid magnet as a spatial reference for imaging. A prototype instrument has demonstrated imaging of uncoated silk, magnetic steel wool, and micron-sized single strand tungsten wires.

  4. Temporal solitons in air

    NASA Astrophysics Data System (ADS)

    Voronin, A. A.; Zheltikov, A. M.

    2017-02-01

    Analysis of the group-velocity dispersion (GVD) of atmospheric air with a model that includes the entire manifold of infrared transitions in air reveals a remarkably broad and continuous anomalous-GVD region in the high-frequency wing of the carbon dioxide rovibrational band from approximately 3.5 to 4.2 μm where atmospheric air is still highly transparent and where high-peak-power sources of ultrashort midinfrared pulses are available. Within this range, anomalous dispersion acting jointly with optical nonlinearity of atmospheric air is shown to give rise to a unique three-dimensional dynamics with well-resolved soliton features in the time domain, enabling a highly efficient whole-beam soliton self-compression of such pulses to few-cycle pulse widths.

  5. Velocity ratio and its application to predicting velocities

    USGS Publications Warehouse

    Lee, Myung W.

    2003-01-01

    The velocity ratio of water-saturated sediment derived from the Biot-Gassmann theory depends mainly on the Biot coefficient?a property of dry rock?for consolidated sediments with porosity less than the critical porosity. With this theory, the shear moduli of dry sediments are the same as the shear moduli of water-saturated sediments. Because the velocity ratio depends on the Biot coefficient explicitly, Biot-Gassmann theory accurately predicts velocity ratios with respect to differential pressure for a given porosity. However, because the velocity ratio is weakly related to porosity, it is not appropriate to investigate the velocity ratio with respect to porosity (f). A new formulation based on the assumption that the velocity ratio is a function of (1?f)n yields a velocity ratio that depends on porosity, but not on the Biot coefficient explicitly. Unlike the Biot-Gassmann theory, the shear moduli of water-saturated sediments depend not only on the Biot coefficient but also on the pore fluid. This nonclassical behavior of the shear modulus of water-saturated sediment is speculated to be an effect of interaction between fluid and the solid matrix, resulting in softening or hardening of the rock frame and an effect of velocity dispersion owing to local fluid flow. The exponent n controls the degree of softening/hardening of the formation. Based on laboratory data measured near 1 MHz, this theory is extended to include the effect of differential pressure on the velocity ratio by making n a function of differential pressure and consolidation. However, the velocity dispersion and anisotropy are not included in the formulation.

  6. On Air Shutter for Cold Storage Room

    NASA Astrophysics Data System (ADS)

    Fukuhara, Isamu; Tsuji, Katsuhiko

    Air curtains are frequently placed at doorway of cold storage room or freezing chamber. As an opening of jet flow in these air curtains is relatively narrow and speed of jet flow is fast, air entrained from surroundings increases in quantity. Therefore, we consider that jet flow with narrow opening can not effectively isolate inside air from the external atmosphere, but the one with relatively wide opening can decrease air entrained from surroundings. Then, when air curtain which has a wide opening (we call it air shutter) is installed at cold storage room, and isolating performances of air shutter are compared with the air curtain. First, as various conditions can be easily changed in numerical calculation, we compare a velocity and temperature field in cold storage room under these conditions when velocity of jet flow is changed by using numerical method. Second, we measure a temperature and velocity distribution in an actual cold storage room under three conditions (air shutter operates, air curtain operates and no operation). From these results, it was found that air shutter is more efficient than air curtain.

  7. High Velocity Clouds

    NASA Technical Reports Server (NTRS)

    Wolfire, M. G.; McKee, C. F.; Hollenbach, D. J.; Tielens, A. G. G. M.; Morrison, David (Technical Monitor)

    1994-01-01

    We calculate the thermal equilibrium gas temperature of high velocity clouds (HVCs) in the Galactic Halo. Our method accounts for the photoelectric heating from small grains and PAHs, and includes a detailed treatment of the ionization rates and heating due to the soft X-ray background and due to cosmic rays. Phase diagrams (thermal pressure P versus gas density n) are presented for gas with a range of dust/gas ratios (D/G) and a range of metallicities (Z). Variations in D/G affect mainly the photoelectric heating rate, while variations in Z affect both the photoelectric heating and gas cooling. Curves are shown for D/G = 1 (local value) to D/G less than approx. equal to 0.005 and for Z=1 (local value) to Z= 0.005. We find that a two phase medium (CNM + WNM) can be in pressure equilibrium with a hot (T approximately 1-2 x 10(exp 6) K) halo within a range of permitted pressures, P(sup min) to P(sup max). We take halo parameters consistent with observed properties of the soft X-ray background. In general, both P(sup min) and P(sup max) decrease with lower D/G due to a drop in photoelectric heating from grains, while. P(sup min) and P(sup max) increase with lower Z due to a drop in gas coolants. We demonstrate that successful two phase models can be constructed with pressure in the range 10(exp 3) less than approximately equal to P/k less than approximately equal to 10(exp 4) K cm(exp -3) consistent with the thermal pressure in the Galactic disk. In addition, using the observed relation between CNM density and distance in HVCs, (n = 75/fDkpc cm(exp -3); Wakker & Schwarz 1991, AA, 250, 484) we show that our pressure curves constrain the allowed range of HVC heights to be between 0.3 - 16 kpc.

  8. Multi-Velocity Component LDV

    NASA Technical Reports Server (NTRS)

    Johnson, Dennis A. (Inventor)

    1996-01-01

    A laser doppler velocimeter uses frequency shifting of a laser beam to provide signal information for each velocity component. A composite electrical signal generated by a light detector is digitized and a processor produces a discrete Fourier transform based on the digitized electrical signal. The transform includes two peak frequencies corresponding to the two velocity components.

  9. Instantaneous Velocity Using Photogate Timers

    ERIC Educational Resources Information Center

    Wolbeck, John

    2010-01-01

    Photogate timers are commonly used in physics laboratories to determine the velocity of a passing object. In this application a card attached to a moving object breaks the beam of the photogate timer providing the time for the card to pass. The length L of the passing card can then be divided by this time to yield the average velocity (or speed)…

  10. Transverse Velocity Shifts in Protostellar Jets: Rotation or Velocity Asymmetries?

    NASA Astrophysics Data System (ADS)

    De Colle, Fabio; Cerqueira, Adriano H.; Riera, Angels

    2016-12-01

    Observations of several protostellar jets show systematic differences in radial velocity transverse to the jet propagation direction that have been interpreted as evidence of rotation in the jets. In this paper we discuss the origin of these velocity shifts, and show that they could originate from rotation in the flow, or from side-to-side asymmetries in the shock velocity, which could be due to asymmetries in the jet ejection velocity/density or in the ambient medium. For typical poloidal jet velocities (˜100-200 km s-1), an asymmetry ≳10% can produce velocity shifts comparable to those observed. We also present three-dimensional numerical simulations of rotating, precessing, and asymmetric jets, and show that, even though for a given jet there is a clear degeneracy between these effects, a statistical analysis of jets with different inclination angles can help to distinguish between the alternative origins of transverse velocity shifts (TVSs). Our analysis indicates that side-to-side velocitiy asymmetries could represent an important contribution to TVSs, being the most important contributor for large jet inclination angles (with respect the the plane of the sky), and cannot be neglected when interpreting the observations.

  11. Temperature and velocity profiles in sooting free boundary layer flames

    NASA Technical Reports Server (NTRS)

    Ang, J. A.; Pagni, P. J.; Mataga, T. G.; Margle, J. M.; Lyons, V. J.

    1986-01-01

    Temperature and velocity profiles are presented for cyclohexane, n-heptane, and iso-octane free, laminar, boundary layer, sooting, diffusion flames. Temperatures are measured with 3 mil Pt/Pt-13 percent Rh thermocouples. Corrected gas temperatures are derived by performing an energy balance of convection to and radiation from the thermocouple bead incorporating the variation of air conductivity and platinum emissivity with temperature. Velocities are measured using laser doppler velocimetry techniques. Profiles are compared with previously reported analytic temperature and velocity fields. Comparison of theoretical and experimental temperature profiles suggests improvement in the analytical treatment is needed, which accounts more accurately for the local soot radiation. The velocity profiles are in good agreement, with the departure of the theory from observation partially due to the small fluctuations inherent in these free flows.

  12. Egomotion Estimation with Optic Flow and Air Velocity Sensors

    DTIC Science & Technology

    2012-01-22

    any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN... control their absolute ego- motion (i.e. groundspeed). The egomotion estimation method that we have developed, which we call the opto-aeronautic algorithm...that some insects can control their groundspeed in an absolute sense, particularly in insects that use pheromones to attract and find mates. In several

  13. Egomotion Estimation with Optic Flow and Air Velocity Sensors

    DTIC Science & Technology

    2012-09-17

    currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED...insects are able to estimate the wind direction and control their absolute ego- motion (i.e. groundspeed). The egomotion estimation method that we have...equation (1). w(t) = vg(t)− va(t) (1) There is evidence that some insects can control their groundspeed in an absolute sense, particularly in insects that

  14. Coherent Doppler Lidar for Measuring Altitude, Ground Velocity, and Air Velocity of Aircraft and Spaceborne Vehicles

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin (Inventor); Pierrottet, Diego F. (Inventor)

    2015-01-01

    A Doppler lidar sensor system includes a laser generator that produces a highly pure single frequency laser beam, and a frequency modulator that modulates the laser beam with a highly linear frequency waveform. A first portion of the frequency modulated laser beam is amplified, and parts thereof are transmitted through at least three separate transmit/receive lenses. A second portion of the laser beam is used as a local oscillator beam for optical heterodyne detection. Radiation from the parts of the laser beam transmitted via the transmit/receive lenses is received by the respective transmit/receive lenses that transmitted the respective part of the laser beam. The received reflected radiation is compared with the local oscillator beam to calculate the frequency difference there between to determine various navigational data.

  15. Simultaneous Temperature and Velocity Measurements in a Large-Scale, Supersonic, Heated Jet

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Magnotti, G.; Bivolaru, D.; Tedder, S.; Cutler, A. D.

    2008-01-01

    Two laser-based measurement techniques have been used to characterize an axisymmetric, combustion-heated supersonic jet issuing into static room air. The dual-pump coherent anti-Stokes Raman spectroscopy (CARS) measurement technique measured temperature and concentration while the interferometric Rayleigh scattering (IRS) method simultaneously measured two components of velocity. This paper reports a preliminary analysis of CARS-IRS temperature and velocity measurements from selected measurement locations. The temperature measurements show that the temperature along the jet axis remains constant while dropping off radially. The velocity measurements show that the nozzle exit velocity fluctuations are about 3% of the maximum velocity in the flow.

  16. Hyperbolic-symmetry vector fields.

    PubMed

    Gao, Xu-Zhen; Pan, Yue; Cai, Meng-Qiang; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian

    2015-12-14

    We present and construct a new kind of orthogonal coordinate system, hyperbolic coordinate system. We present and design a new kind of local linearly polarized vector fields, which is defined as the hyperbolic-symmetry vector fields because the points with the same polarization form a series of hyperbolae. We experimentally demonstrate the generation of such a kind of hyperbolic-symmetry vector optical fields. In particular, we also study the modified hyperbolic-symmetry vector optical fields with the twofold and fourfold symmetric states of polarization when introducing the mirror symmetry. The tight focusing behaviors of these vector fields are also investigated. In addition, we also fabricate micro-structures on the K9 glass surfaces by several tightly focused (modified) hyperbolic-symmetry vector fields patterns, which demonstrate that the simulated tightly focused fields are in good agreement with the fabricated micro-structures.

  17. Extended vector-tensor theories

    NASA Astrophysics Data System (ADS)

    Kimura, Rampei; Naruko, Atsushi; Yoshida, Daisuke

    2017-01-01

    Recently, several extensions of massive vector theory in curved space-time have been proposed in many literatures. In this paper, we consider the most general vector-tensor theories that contain up to two derivatives with respect to metric and vector field. By imposing a degeneracy condition of the Lagrangian in the context of ADM decomposition of space-time to eliminate an unwanted mode, we construct a new class of massive vector theories where five degrees of freedom can propagate, corresponding to three for massive vector modes and two for massless tensor modes. We find that the generalized Proca and the beyond generalized Proca theories up to the quartic Lagrangian, which should be included in this formulation, are degenerate theories even in curved space-time. Finally, introducing new metric and vector field transformations, we investigate the properties of thus obtained theories under such transformations.

  18. Earthquake slip vectors and estimates of present-day plate motions

    NASA Technical Reports Server (NTRS)

    Demets, Charles

    1993-01-01

    Two alternative models for present-day global plate motions are derived from subsets of the NUVEL-1 data in order to investigate the degree to which earthquake slip vectors affect the NUVEL-1 model and to provide estimates of present-day plate velocities that are independent of earthquake slip vectors. The data set used to derive the first model excludes subduction zone slip vectors. The primary purpose of this model is to demonstrate that the 240 subduction zone slip vectors in the NUVEL-1 data set do not greatly affect the plate velocities predicted by NUVEL-1. A data set that excludes all of the 724 earthquake slip vectors used to derive NUVEL-1 is used to derive the second model. This model is suitable as a reference model for kinematic studies that require plate velocity estimates unaffected by earthquake slip vectors. The slip-dependent slip vector bias along transform faults is investigated using the second model, and evidence is sought for biases in slip directions along spreading centers.

  19. Velocity and drop size measurements in a confined, swirl-stabilized, combusting spray

    NASA Technical Reports Server (NTRS)

    Bulzan, Daniel L.

    1996-01-01

    Drop size and velocity measurements in a confined, swirl-stabilized, reacting spray are presented. The configuration consisted of a center-mounted research air-assist atomizer surrounded by a coflowing air stream. A quartz tube surrounded the burner and provided the confinement. Both the air-assist and coflow streams had swirl imparted to them in the same direction with 45-degree-angle swirlers. The fuel and air entered the combustor at ambient temperature. The gas-phase measurements reported were obtained from the velocity drops with a mean diameter of four microns. Heptane fuel was used for all the experiments. Measurements of drop size and velocity, gas-phase velocity and drop number flux are reported for axial distances of 23, 5, 10, 15, 25, and 50 mm downstream of the nozzle. The measurements were performed using a two-component phase/Doppler particle analyzer. Profiles across the entire flowfield are presented.

  20. The Newcomb & Michelson Velocity of Light Experiments

    NASA Astrophysics Data System (ADS)

    Carter, W. E.

    2002-05-01

    Simon Newcomb (1835-1909) is remembered as the leading American mathematical astronomer of the 19th century; Albert Michelson (1852-1931) as the leading optical experimentalist of his era, and the first American to win the Nobel Prize in physics (1907). Newcomb first became interested in measuring the velocity of light to better determine the scale of the solar system. Ensign Michelson began his velocity of light experiments while preparing to teach physics at the U.S. Naval Academy, in Annapolis, Maryland. Using private funding and Naval Academy facilities, in January 1879, Michelson obtained a value of 299,910 km/sec. In March of that same year Newcomb received an appropriation of five thousand dollars and Michelson was detailed to the U.S. Naval Observatory (USNO) to assist with experiments in Washington D. C. The instrument designed by Newcomb used a four-sided solid steel rotating mirror to avoid a failure of the type Michelson had experienced when a thin glass mirror failed from centrifugal force. The mirror was driven by compressed air operating on fan wheels at each end of the assembly. Rotation rates of 250 rev/sec were possible, in both directions, and the rate could be varied minutely by adjusting conflicting air jets. Ft. Meyers was selected for the primary station, and fixed mirror stations were placed at USNO (Foggy Bottom) and the Washington Monument. The U.S. Coast and Geodetic Survey (USC&GS) determined the distances from the rotating mirror to the fixed mirrors. They first established a few hundred meter long baseline on Analostan Island, in the Potomac River, using 4 meter long agate capped steel slide-rods. Triangulation was then used to extend the network to each of the reflector stations. Michelson participated in the Washington D.C. observations until September 1880, when he was granted a leave of absence by the Navy to study in Europe. Newcomb continued the experiments for two more years. In his final report, Newcomb gave two values for the

  1. Measurements of wind vectors, eddy momentum transports, and energy conversions in Jupiter's atmosphere from Voyager 1 images

    NASA Technical Reports Server (NTRS)

    Beebe, R. F.; Ingersoll, A. P.; Hunt, G. E.; Muller, J.-P.; Mitchell, J. L.

    1980-01-01

    Voyager 1 narrow-angle images were used to obtain displacements of features down to 100 to 200 km in size over intervals of 10 hours. A global map of velocity vectors and longitudinally averaged zonal wind vectors as functions of the latitude, is presented and discussed

  2. Introductory labs on the vector nature of force and acceleration

    NASA Astrophysics Data System (ADS)

    Kanim, Stephen E.; Subero, Keron

    2010-05-01

    We discuss the use of long-exposure digital photography in introductory mechanics laboratories. Students at New Mexico State University use inexpensive digital cameras to record the motion of objects with attached blinking light emitting diodes. These photographs are used to make inferences about the velocity and acceleration of the moving object. We use the analysis of these photographs to promote student understanding of the vector nature of kinematics quantities. In subsequent laboratories we build on this understanding to help students relate the acceleration vector for a moving object to the net force vector for that object. We give details about the equipment we use and describe the sequence of activities that we have developed for a two-dimensional motion laboratory and for a laboratory on Newton's second law. Finally we present some pre- and post-test data on questions related to the concepts underlying these laboratories.

  3. Safety considerations in vector development.

    PubMed

    Kappes, J C; Wu, X

    2001-11-01

    The inadvertent production of replication competent retrovirus (RCR) constitutes the principal safety concern for the use of lentiviral vectors in human clinical protocols. Because of limitations in animal models to evaluate lentiviral vectors for their potential to recombine and induce disease, the vector design itself should ensure against the emergence of RCR in vivo. Issues related to RCR generation and one approach to dealing with this problem are discussed in this chapter. To assess the risk of generating RCR, a highly sensitive biological assay was developed to specifically detect vector recombination in transduced cells. Analysis of lentiviral vector stocks has shown that recombination occurs during reverse transcription in primary target cells. Rejoining of viral protein-coding sequences of the packaging construct and cis-acting sequences of the vector was demonstrated to generate env-minus recombinants (LTR-gag-pol-LTR). Mobilization of recombinant lentiviral genomes was also demonstrated but was dependent on pseudotyping of the vector core with an exogenous envelope protein. 5' sequence analysis has demonstrated that recombinants consist of U3, R, U5, and the psi packaging signal joined with an open gag coding region. Analysis of the 3' end has mapped the point of vector recombination to the poly(A) tract of the packaging construct's mRNA. The state-of-the-art third generation packaging construct and SIN vector also have been shown to generate env-minus proviral recombinants capable of mobilizing retroviral DNA when pseudotyped with an exogenous envelope protein. A new class of HIV-based vector (trans-vector) was recently developed that splits the gag-pol component of the packaging construct into two parts: one that expresses Gag/Gag-Pro and another that expresses Pol (RT and IN) fused with Vpr. Unlike other lentiviral vectors, the trans-vector has not been shown to form recombinants capable of DNA mobilization. These results indicate the trans-vector

  4. Three Component Velocity and Acceleration Measurement Using FLEET

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; Bathel, Brett F.; Calvert, Nathan; Dogariu, Arthur; Miles, Richard P.

    2014-01-01

    The femtosecond laser electronic excitation and tagging (FLEET) method has been used to measure three components of velocity and acceleration for the first time. A jet of pure N2 issuing into atmospheric pressure air was probed by the FLEET system. The femtosecond laser was focused down to a point to create a small measurement volume in the flow. The long-lived lifetime of this fluorescence was used to measure the location of the tagged particles at different times. Simultaneous images of the flow were taken from two orthogonal views using a mirror assembly and a single intensified CCD camera, allowing two components of velocity to be measured in each view. These different velocity components were combined to determine three orthogonal velocity components. The differences between subsequent velocity components could be used to measure the acceleration. Velocity accuracy and precision were roughly estimated to be +/-4 m/s and +/-10 m/s respectively. These errors were small compared to the approx. 100 m/s velocity of the subsonic jet studied.

  5. Multistage vector (MSV) therapeutics.

    PubMed

    Wolfram, Joy; Shen, Haifa; Ferrari, Mauro

    2015-12-10

    One of the greatest challenges in the field of medicine is obtaining controlled distribution of systemically administered therapeutic agents within the body. Indeed, biological barriers such as physical compartmentalization, pressure gradients, and excretion pathways adversely affect localized delivery of drugs to pathological tissue. The diverse nature of these barriers requires the use of multifunctional drug delivery vehicles that can overcome a wide range of sequential obstacles. In this review, we explore the role of multifunctionality in nanomedicine by primarily focusing on multistage vectors (MSVs). The MSV is an example of a promising therapeutic platform that incorporates several components, including a microparticle, nanoparticles, and small molecules. In particular, these components are activated in a sequential manner in order to successively address transport barriers.

  6. Entangled vector vortex beams

    NASA Astrophysics Data System (ADS)

    D'Ambrosio, Vincenzo; Carvacho, Gonzalo; Graffitti, Francesco; Vitelli, Chiara; Piccirillo, Bruno; Marrucci, Lorenzo; Sciarrino, Fabio

    2016-09-01

    Light beams having a vectorial field structure, or polarization, that varies over the transverse profile and a central optical singularity are called vector vortex (VV) beams and may exhibit specific properties such as focusing into "light needles" or rotation invariance. VV beams have already found applications in areas ranging from microscopy to metrology, optical trapping, nano-optics, and quantum communication. Individual photons in such beams exhibit a form of single-particle quantum entanglement between different degrees of freedom. On the other hand, the quantum states of two photons can be also entangled with each other. Here, we combine these two concepts and demonstrate the generation of quantum entanglement between two photons that are both in VV states: a form of entanglement between two complex vectorial fields. This result may lead to quantum-enhanced applications of VV beams as well as to quantum information protocols fully exploiting the vectorial features of light.

  7. Multistage vector (MSV) therapeutics

    PubMed Central

    Wolfram, Joy; Shen, Haifa; Ferrari, Mauro

    2015-01-01

    One of the greatest challenges in the field of medicine is obtaining controlled distribution of systemically administered therapeutic agents within the body. Indeed, biological barriers such as physical compartmentalization, pressure gradients, and excretion pathways adversely affect localized delivery of drugs to pathological tissue. The diverse nature of these barriers requires the use of multifunctional drug delivery vehicles that can overcome a wide range of sequential obstacles. In this review, we explore the role of multifunctionality in nanomedicine by primarily focusing on multistage vectors (MSVs). The MSV is an example of a promising therapeutic platform that incorporates several components, including a microparticle, nanoparticles, and small molecules. In particular, these components are activated in a sequential manner in order to successively address transport barriers. PMID:26264836

  8. Solar imaging vector magnetograph

    NASA Technical Reports Server (NTRS)

    Canfield, Richard C.

    1993-01-01

    This report describes an instrument which has been constructed at the University of Hawaii to make observations of the magnetic field in solar active regions. Detailed knowledge of active region magnetic structures is crucial to understanding many solar phenomena, because the magnetic field both defines the morphology of structures seen in the solar atmosphere and is the apparent energy source for solar flares. The new vector magnetograph was conceived in response to a perceived discrepancy between the capabilities of X ray imaging telescopes to be operating during the current solar maximum and those of existing magnetographs. There were no space-based magnetographs planned for this period; the existing ground-based instruments variously suffered from lack of sensitivity, poor time resolution, inadequate spatial resolution or unreliable sites. Yet the studies of flares and their relationship to the solar corona planned for the 1991-1994 maximum absolutely required high quality vector magnetic field measurements. By 'vector' measurements we mean that the observation attempts to deduce the complete strength and direction of the field at the measurement site, rather than just the line of sight component as obtained by a traditional longitudinal magnetograph. Knowledge of the vector field permits one to calculate photospheric electric currents, which might play a part in heating the corona, and to calculate energy stored in coronal magnetic fields as the result of such currents. Information about the strength and direction of magnetic fields in the solar atmosphere can be obtained in a number of ways, but quantitative data is best obtained by observing Zeeman-effect polarization in solar spectral lines. The technique requires measuring the complete state of polarization at one or more wavelengths within a magnetically sensitive line of the solar spectrum. This measurement must be done for each independent spatial point for which one wants magnetic field data. All the

  9. Chameleon vector bosons

    SciTech Connect

    Nelson, Ann E.

    2008-05-01

    We show that for a force mediated by a vector particle coupled to a conserved U(1) charge, the apparent range and strength can depend on the size and density of the source, and the proximity to other sources. This chameleon effect is due to screening from a light charged scalar. Such screening can weaken astrophysical constraints on new gauge bosons. As an example we consider the constraints on chameleonic gauged B-L. We show that although Casimir measurements greatly constrain any B-L force much stronger than gravity with range longer than 0.1 {mu}m, there remains an experimental window for a long-range chameleonic B-L force. Such a force could be much stronger than gravity, and long or infinite range in vacuum, but have an effective range near the surface of the earth which is less than a micron.

  10. Slip velocity and velocity inversion in a cylindrical Couette flow.

    PubMed

    Kim, Sangrak

    2009-03-01

    Velocity inversion in a nanoscale cylindrical Couette flow is investigated with the Navier-Stokes (NS) equation and molecular-dynamics (MD) simulation. With general slip boundary conditions in the NS equation, the flow can be classified into five distinct profiles. The condition of velocity inversion is explored in the whole space of four dimensionless variables of beta , slip velocity ratio u('), radius ratio a('), and angular velocity ratio omega('). MD computer simulations are performed to estimate the constitutive coefficient of the slip velocities at the walls. The flow is generated by a rotating inner wall and a stationary outer wall in conformity with the theoretical result. By varying an attraction parameter in the Lennard-Jones potential, the slip velocities can be easily controlled. The theoretical predictions are compared with the simulation results. We find that in the intermediate range of the attraction parameter the two results are quite comparable to some extent, but at both extreme values of the attraction parameter, they are quite different.

  11. Horns as particle velocity amplifiers.

    PubMed

    Donskoy, Dimitri M; Cray, Benjamin A

    2011-11-01

    Preliminary measurements and numerical predictions reveal that simple, and relatively small, horns generate remarkable amplification of acoustic particle velocity. For example, below 2 kHz, a 2.5 cm conical horn has a uniform velocity amplification ratio (throat-to-mouth) factor of approximately 3, or, in terms of a decibel level, 9.5 dB. It is shown that the velocity amplification factor depends on the horn's mouth-to-throat ratio as well as, though to a lesser degree, the horn's flare rate. A double horn configuration provides limited additional gain, approximately an increase of up to 25%.

  12. Dendritic Growth Velocities in Microgravity

    NASA Technical Reports Server (NTRS)

    Glicksman, M. E.; Koss, M. B.; Winsa, E. A.

    1994-01-01

    We measured dendritic tip velocities in pure succinonitrile (SCN) in microgravity. using a sequence of telemetered binary images sent to Earth from the Space Shuttle Columbia (STS-62). Growth velocities were measured as a function of the supercooling over the range 0.05-1.5 K. Microgravity observations show that buoyancy-induced convection alters the growth kinetics of SCN dendrites at supercooling as high as 1.3 K. Also, the dendrite velocity data measured under microgravity agree well with the Ivantsov paraboloidal diffusion solution when coupled to a scaling constant of sigma(sup *) = 0.0157.

  13. Image segmentation via motion vector estimates

    NASA Astrophysics Data System (ADS)

    Abdel-Malek, Aiman A.; Hasekioglu, Orkun; Bloomer, John J.

    1990-07-01

    In the visual world moving edges in the periphery represent vital pieces of information that directs the human foveation mechanism to selectively gather information around these specific locations. This computationally efficient approach of allocating resources at key locations has inspired computer visionists to develop new target detection and hacking algorithms based on motion detection in image sequences. In this study we implemented a recursive algorithm for estimating motion vector fields for each pixel in a sequence of Digital Subtraction Angiography (DSA) images. Velocity information is used to segment the image and perform linear quadratic and acceleration-based frame interpolation to produce an apparent frame rate increase. Our results demonstrate the feasibility of low-rate digital fluoroscopy hence less exposure risks while preserving image quality. Furthermore the technique can be useful in the medical Picture Archival and Communication Systems (PACS) where image data can be compressed by storing and transmiting only the motion fields associated with the moving pixels. 1.

  14. Threshold friction velocity influenced by wetness of soils within the Columbia Plateau

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Windblown dust impacts air quality in the Columbia Plateau of the U.S. Pacific Northwest. Wind erosion of agricultural lands, which is the predominate source of windblown dust in the region, occurs when the friction velocity exceeds the threshold friction velocity (TFV) of the surface. Soil moisture...

  15. Poynting vector and wave vector directions of equatorial chorus

    NASA Astrophysics Data System (ADS)

    Taubenschuss, Ulrich; Santolík, Ondřej; Breuillard, Hugo; Li, Wen; Le Contel, Olivier

    2016-12-01

    We present new results on wave vectors and Poynting vectors of chorus rising and falling tones on the basis of 6 years of THEMIS (Time History of Events and Macroscale Interactions during Substorms) observations. The majority of wave vectors is closely aligned with the direction of the ambient magnetic field (B0). Oblique wave vectors are confined to the magnetic meridional plane, pointing away from Earth. Poynting vectors are found to be almost parallel to B0. We show, for the first time, that slightly oblique Poynting vectors are directed away from Earth for rising tones and toward Earth for falling tones. For the majority of lower band chorus elements, the mutual orientation between Poynting vectors and wave vectors can be explained by whistler mode dispersion in a homogeneous collisionless cold plasma. Upper band chorus seems to require inclusion of collisional processes or taking into account azimuthal anisotropies in the propagation medium. The latitudinal extension of the equatorial source region can be limited to ±6∘ around the B0 minimum or approximately ±5000 km along magnetic field lines. We find increasing Poynting flux and focusing of Poynting vectors on the B0 direction with increasing latitude. Also, wave vectors become most often more field aligned. A smaller group of chorus generated with very oblique wave normals tends to stay close to the whistler mode resonance cone. This suggests that close to the equatorial source region (within ˜20∘ latitude), a wave guidance mechanism is relevant, for example, in ducts of depleted or enhanced plasma density.

  16. Orbital Transfer Vehicle Engine Technology High Velocity Ratio Diffusing Crossover

    NASA Technical Reports Server (NTRS)

    Lariviere, Brian W.

    1992-01-01

    High speed, high efficiency head rise multistage pumps require continuous passage diffusing crossovers to effectively convey the pumped fluid from the exit of one impeller to the inlet of the next impeller. On Rocketdyne's Orbital Transfer Vehicle (OTV), the MK49-F, a three stage high pressure liquid hydrogen turbopump, utilizes a 6.23 velocity ratio diffusing crossover. This velocity ratio approaches the diffusion limits for stable and efficient flow over the operating conditions required by the OTV system. The design of the high velocity ratio diffusing crossover was based on advanced analytical techniques anchored by previous tests of stationary two-dimensional diffusers with steady flow. To secure the design and the analytical techniques, tests were required with the unsteady whirling characteristics produced by an impeller. A tester was designed and fabricated using a 2.85 times scale model of the MK49-F turbopumps first stage, including the inducer, impeller, and the diffusing crossover. Water and air tests were completed to evaluate the large scale turbulence, non-uniform velocity, and non-steady velocity on the pump and crossover head and efficiency. Suction performance tests from 80 percent to 124 percent of design flow were completed in water to assess these pump characteristics. Pump and diffuser performance from the water and air tests were compared with the actual MK49-F test data in liquid hydrogen.

  17. Orbital transfer vehicle engine technology high velocity ratio diffusing crossover

    NASA Astrophysics Data System (ADS)

    Lariviere, Brian W.

    1992-12-01

    High speed, high efficiency head rise multistage pumps require continuous passage diffusing crossovers to effectively convey the pumped fluid from the exit of one impeller to the inlet of the next impeller. On Rocketdyne's Orbital Transfer Vehicle (OTV), the MK49-F, a three stage high pressure liquid hydrogen turbopump, utilizes a 6.23 velocity ratio diffusing crossover. This velocity ratio approaches the diffusion limits for stable and efficient flow over the operating conditions required by the OTV system. The design of the high velocity ratio diffusing crossover was based on advanced analytical techniques anchored by previous tests of stationary two-dimensional diffusers with steady flow. To secure the design and the analytical techniques, tests were required with the unsteady whirling characteristics produced by an impeller. A tester was designed and fabricated using a 2.85 times scale model of the MK49-F turbopumps first stage, including the inducer, impeller, and the diffusing crossover. Water and air tests were completed to evaluate the large scale turbulence, non-uniform velocity, and non-steady velocity on the pump and crossover head and efficiency. Suction performance tests from 80 percent to 124 percent of design flow were completed in water to assess these pump characteristics. Pump and diffuser performance from the water and air tests were compared with the actual MK49-F test data in liquid hydrogen.

  18. Velocity measurements of low Reynolds number tube flow using fiber-optic technology

    SciTech Connect

    Bianchi, J. Christopher

    1993-03-01

    In 1988 Nielsen started work to measure the spatial variability of the mass flux vector being transported in a porous medium. To measure the spatial variability of the mass flux vector, the spatial variability of its components(velocity, concentration) must be measured. Nielsen was successful in measuring the pore level concentration at many different pores and in verifying the assumption that a nonuniform concentration field exists within the mixing zone between two miscible fluids. However, Nielsen was unable to conduct the necessary pore level velocity measurements needed. Nielsen`s work is being continued and a probe is being developed that will measure both velocity and concentration components at pore level. The probe is essentially the same probe used to make the pore level concentration measurements with added capabilities needed to make the velocity measurements. This probe has several design variables, dealing primarily with the velocity component, that need further investigation. The research presented in this thesis investigates these parameters by performing experiments in a capillary tube. The tube is a controlled system where the velocity of the fluid can be determined from the volumetric flow rate using Poiseuille`s solution for viscous flow. Also, a statistically based relationship between the velocity measured with the probe and the velocity determined from the volumetric flow rate has been developed.

  19. Velocity measurements of low Reynolds number tube flow using fiber-optic technology

    SciTech Connect

    Bianchi, J.C.

    1993-03-01

    In 1988 Nielsen started work to measure the spatial variability of the mass flux vector being transported in a porous medium. To measure the spatial variability of the mass flux vector, the spatial variability of its components(velocity, concentration) must be measured. Nielsen was successful in measuring the pore level concentration at many different pores and in verifying the assumption that a nonuniform concentration field exists within the mixing zone between two miscible fluids. However, Nielsen was unable to conduct the necessary pore level velocity measurements needed. Nielsen's work is being continued and a probe is being developed that will measure both velocity and concentration components at pore level. The probe is essentially the same probe used to make the pore level concentration measurements with added capabilities needed to make the velocity measurements. This probe has several design variables, dealing primarily with the velocity component, that need further investigation. The research presented in this thesis investigates these parameters by performing experiments in a capillary tube. The tube is a controlled system where the velocity of the fluid can be determined from the volumetric flow rate using Poiseuille's solution for viscous flow. Also, a statistically based relationship between the velocity measured with the probe and the velocity determined from the volumetric flow rate has been developed.

  20. Robust, automatic GPS station velocities and velocity time series

    NASA Astrophysics Data System (ADS)

    Blewitt, G.; Kreemer, C.; Hammond, W. C.

    2014-12-01

    Automation in GPS coordinate time series analysis makes results more objective and reproducible, but not necessarily as robust as the human eye to detect problems. Moreover, it is not a realistic option to manually scan our current load of >20,000 time series per day. This motivates us to find an automatic way to estimate station velocities that is robust to outliers, discontinuities, seasonality, and noise characteristics (e.g., heteroscedasticity). Here we present a non-parametric method based on the Theil-Sen estimator, defined as the median of velocities vij=(xj-xi)/(tj-ti) computed between all pairs (i, j). Theil-Sen estimators produce statistically identical solutions to ordinary least squares for normally distributed data, but they can tolerate up to 29% of data being problematic. To mitigate seasonality, our proposed estimator only uses pairs approximately separated by an integer number of years (N-δt)<(tj-ti )<(N+δt), where δt is chosen to be small enough to capture seasonality, yet large enough to reduce random error. We fix N=1 to maximally protect against discontinuities. In addition to estimating an overall velocity, we also use these pairs to estimate velocity time series. To test our methods, we process real data sets that have already been used with velocities published in the NA12 reference frame. Accuracy can be tested by the scatter of horizontal velocities in the North American plate interior, which is known to be stable to ~0.3 mm/yr. This presents new opportunities for time series interpretation. For example, the pattern of velocity variations at the interannual scale can help separate tectonic from hydrological processes. Without any step detection, velocity estimates prove to be robust for stations affected by the Mw7.2 2010 El Mayor-Cucapah earthquake, and velocity time series show a clear change after the earthquake, without any of the usual parametric constraints, such as relaxation of postseismic velocities to their preseismic values.

  1. Choice of velocity variables for complex flow computation

    NASA Technical Reports Server (NTRS)

    Shyy, W.; Chang, G. C.

    1991-01-01

    The issue of adopting the velocity components as dependent velocity variables for the Navier-Stokes flow computations is investigated. The viewpoint advocated is that a numerical algorithm should preferably honor both the physical conservation law in differential form and the geometric conservation law in discrete form. With the use of Cartesian velocity vector, the momentum equations in curvilinear coordinates can retain the full conservation-law form and satisfy the physical conservation laws. With the curvilinear velocity components, source terms appear in differential equations and hence the full conservation law form can not be retained. In discrete expressions, algorithms based on the Cartesian components can satisfy the geometric conservation-law form for convection terms but not for viscous terms; those based on the curvilinear components, on the other hand, cannot satisfy the geometric conservation-law form for either convection or viscous terms. Several flow solutions for domain with 90 and 360 degree turnings are presented to illustrate the issues of using the Cartesian velocity components and the staggered grid arrangement.

  2. Velocity of climate change algorithms for guiding conservation and management.

    PubMed

    Hamann, Andreas; Roberts, David R; Barber, Quinn E; Carroll, Carlos; Nielsen, Scott E

    2015-02-01

    The velocity of climate change is an elegant analytical concept that can be used to evaluate the exposure of organisms to climate change. In essence, one divides the rate of climate change by the rate of spatial climate variability to obtain a speed at which species must migrate over the surface of the earth to maintain constant climate conditions. However, to apply the algorithm for conservation and management purposes, additional information is needed to improve realism at local scales. For example, destination information is needed to ensure that vectors describing speed and direction of required migration do not point toward a climatic cul-de-sac by pointing beyond mountain tops. Here, we present an analytical approach that conforms to standard velocity algorithms if climate equivalents are nearby. Otherwise, the algorithm extends the search for climate refugia, which can be expanded to search for multivariate climate matches. With source and destination information available, forward and backward velocities can be calculated allowing useful inferences about conservation of species (present-to-future velocities) and management of species populations (future-to-present velocities).

  3. Observations of Velocity Conditions near a Hydroelectric Turbine Draft Tube Exit using ADCP Measurements

    SciTech Connect

    Cook, Christopher B.; Richmond, Marshall C.; Serkowski, John A.

    2007-10-01

    Measurement of flow characteristics near hydraulic structures is an ongoing challenge because of the need to obtain rapid measurements of time-varying velocity over a relatively large spatial domain. This paper discusses use of an acoustic Doppler current profiler (ADCP) to measure the rapidly diverging flow exiting from an operating hydroelectric turbine draft tube exit. The resolved three-dimensional velocity vectors show a highly complex and helical flow pattern developed near to and downstream of the exit. Velocity vectors were integrated across the exit and we computed an uneven percentage of flow (67%/33%) passing through the two draft tube barrels at a mid-range turbine discharge, consistent with physical model results. In addition to the three-dimensional velocity vectors, the individual one-dimensional velocities measured by each of the four ADCP beams can be separately used as calibration and validation datasets for numerical and physical models. This technique is demonstrated by comparing along-beam ADCP velocity measurements to data collected in a scaled physical model.

  4. Internal performance characteristics of thrust-vectored axisymmetric ejector nozzles

    NASA Technical Reports Server (NTRS)

    Lamb, Milton

    1995-01-01

    A series of thrust-vectored axisymmetric ejector nozzles were designed and experimentally tested for internal performance and pumping characteristics at the Langley research center. This study indicated that discontinuities in the performance occurred at low primary nozzle pressure ratios and that these discontinuities were mitigated by decreasing expansion area ratio. The addition of secondary flow increased the performance of the nozzles. The mid-to-high range of secondary flow provided the most overall improvements, and the greatest improvements were seen for the largest ejector area ratio. Thrust vectoring the ejector nozzles caused a reduction in performance and discharge coefficient. With or without secondary flow, the vectored ejector nozzles produced thrust vector angles that were equivalent to or greater than the geometric turning angle. With or without secondary flow, spacing ratio (ejector passage symmetry) had little effect on performance (gross thrust ratio), discharge coefficient, or thrust vector angle. For the unvectored ejectors, a small amount of secondary flow was sufficient to reduce the pressure levels on the shroud to provide cooling, but for the vectored ejector nozzles, a larger amount of secondary air was required to reduce the pressure levels to provide cooling.

  5. Kriging interpolating cosmic velocity field

    NASA Astrophysics Data System (ADS)

    Yu, Yu; Zhang, Jun; Jing, Yipeng; Zhang, Pengjie

    2015-10-01

    Volume-weighted statistics of large-scale peculiar velocity is preferred by peculiar velocity cosmology, since it is free of the uncertainties of galaxy density bias entangled in observed number density-weighted statistics. However, measuring the volume-weighted velocity statistics from galaxy (halo/simulation particle) velocity data is challenging. Therefore, the exploration of velocity assignment methods with well-controlled sampling artifacts is of great importance. For the first time, we apply the Kriging interpolation to obtain the volume-weighted velocity field. Kriging is a minimum variance estimator. It predicts the most likely velocity for each place based on the velocity at other places. We test the performance of Kriging quantified by the E-mode velocity power spectrum from simulations. Dependences on the variogram prior used in Kriging, the number nk of the nearby particles to interpolate, and the density nP of the observed sample are investigated. First, we find that Kriging induces 1% and 3% systematics at k ˜0.1 h Mpc-1 when nP˜6 ×1 0-2(h-1 Mpc )-3 and nP˜6 ×1 0-3(h-1 Mpc )-3 , respectively. The deviation increases for decreasing nP and increasing k . When nP≲6 ×1 0-4(h-1 Mpc )-3 , a smoothing effect dominates small scales, causing significant underestimation of the velocity power spectrum. Second, increasing nk helps to recover small-scale power. However, for nP≲6 ×1 0-4(h-1 Mpc )-3 cases, the recovery is limited. Finally, Kriging is more sensitive to the variogram prior for a lower sample density. The most straightforward application of Kriging on the cosmic velocity field does not show obvious advantages over the nearest-particle method [Y. Zheng, P. Zhang, Y. Jing, W. Lin, and J. Pan, Phys. Rev. D 88, 103510 (2013)] and could not be directly applied to cosmology so far. However, whether potential improvements may be achieved by more delicate versions of Kriging is worth further investigation.

  6. [Time lag effect between poplar' s sap flow velocity and microclimate factors in agroforestry system in West Liaoning Province].

    PubMed

    Di, Sun; Guan, De-xin; Yuan, Feng-hui; Wang, An-zhi; Wu, Jia-bing

    2010-11-01

    By using Granier's thermal dissipation probe, the sap flow velocity of the poplars in agroforestry system in west Liaoning was continuously measured, and the microclimate factors were measured synchronously. Dislocation contrast method was applied to analyze the sap flow velocity and corresponding air temperature, air humidity, net radiation, and vapor pressure deficit to discuss the time lag effect between poplar' s sap flow velocity and microclimate factors on sunny days. It was found that the poplar's sap flow velocity advanced of air temperature, air humidity, and vapor pressure deficit, and lagged behind net radiation. The sap flow velocity in June, July, August, and September was advanced of 70, 30, 50, and 90 min to air temperature, of 80, 30, 40, and 90 min to air humidity, and of 90, 50, 70, and 120 min to vapor pressure deficit, but lagged behind 10, 10, 40, and 40 min to net radiation, respectively. The time lag time of net radiation was shorter than that of air temperature, air humidity, and vapor pressure. The regression analysis showed that in the cases the time lag effect was contained and not, the determination coefficients between comprehensive microclimate factor and poplar's sap flow velocity were 0.903 and 0.855, respectively, indicating that when the time lag effect was contained, the determination coefficient was ascended by 2.04%, and thus, the simulation accuracy of poplar's sap flow velocity was improved.

  7. A parabolic velocity-decomposition method for wind turbines

    NASA Astrophysics Data System (ADS)

    Mittal, Anshul; Briley, W. Roger; Sreenivas, Kidambi; Taylor, Lafayette K.

    2017-02-01

    An economical parabolized Navier-Stokes approximation for steady incompressible flow is combined with a compatible wind turbine model to simulate wind turbine flows, both upstream of the turbine and in downstream wake regions. The inviscid parabolizing approximation is based on a Helmholtz decomposition of the secondary velocity vector and physical order-of-magnitude estimates, rather than an axial pressure gradient approximation. The wind turbine is modeled by distributed source-term forces incorporating time-averaged aerodynamic forces generated by a blade-element momentum turbine model. A solution algorithm is given whose dependent variables are streamwise velocity, streamwise vorticity, and pressure, with secondary velocity determined by two-dimensional scalar and vector potentials. In addition to laminar and turbulent boundary-layer test cases, solutions for a streamwise vortex-convection test problem are assessed by mesh refinement and comparison with Navier-Stokes solutions using the same grid. Computed results for a single turbine and a three-turbine array are presented using the NREL offshore 5-MW baseline wind turbine. These are also compared with an unsteady Reynolds-averaged Navier-Stokes solution computed with full rotor resolution. On balance, the agreement in turbine wake predictions for these test cases is very encouraging given the substantial differences in physical modeling fidelity and computer resources required.

  8. Analytical Ultracentrifugation as an Approach to Characterize Recombinant Adeno-Associated Viral Vectors.

    PubMed

    Burnham, Brenda; Nass, Shelley; Kong, Elton; Mattingly, MaryEllen; Woodcock, Denise; Song, Antonius; Wadsworth, Samuel; Cheng, Seng H; Scaria, Abraham; O'Riordan, Catherine R

    2015-12-01

    Recombinant adeno-associated viral (rAAV) vectors represent a novel class of biopharmaceutical drugs. The production of clinical-grade rAAV vectors for gene therapy would benefit from analytical methods that are able to monitor drug product quality with regard to homogeneity, purity, and manufacturing consistency. Here, we demonstrate the novel application of analytical ultracentrifugation (AUC) to characterize the homogeneity of preparations of rAAV vectors. We show that a single sedimentation velocity run of rAAV vectors detected and quantified a number of different viral species, such as vectors harboring an intact genome, lacking a vector genome (empty particles), and containing fragmented or incomplete vector genomes. This information is obtained by direct boundary modeling of the AUC data generated from refractometric or UV detection systems using the computer program SEDFIT. Using AUC, we show that multiple parameters contributed to vector quality, including the AAV genome form (i.e., self-complementary vs. single-stranded), vector genome size, and the production and purification methods. Hence, AUC is a critical tool for identifying optimal production and purification processes and for monitoring the physical attributes of rAAV vectors to ensure their quality.

  9. An experimental validation of a turbulence model for air flow in a mining chamber

    NASA Astrophysics Data System (ADS)

    Branny, M.; Karch, M.; Wodziak, W.; Jaszczur, M.; Nowak, R.; Szmyd, J. S.

    2014-08-01

    In copper mines, excavation chambers are ventilated by jet fans. A fan is installed at the inlet of the dead-end chamber, which is usually 20-30m long. The effectiveness of ventilation depends on the stream range generated by the fan. The velocity field generated by the supply air stream is fully three-dimensional and the flow is turbulent. Currently, the parameters of 3D air flows are determined using the CFD approach. This paper presents the results of experimental testing and numerical simulations of airflow in a laboratory model of a blind channel, aired by a forced ventilation system. The aim of the investigation is qualitative and quantitative verification of computer modelling data. The analysed layout is a geometrically re-scaled and simplified model of a real object. The geometrical scale of the physical model is 1:10. The model walls are smooth, the channel cross-section is rectangular. Measurements were performed for the average airflow velocity in the inlet duct equal 35.4m/s, which gives a Reynolds number of about 180 000. The components of the velocity vector were measured using the Particle Image Velocimetry approach. The numerical procedures presented in this paper use two turbulence models: the standard k-ɛ model and the Reynolds Stress model. The experimental results have been compared against the results of numerical simulations. In the investigated domain of flow - extending from the air inlet to the blind wall of the chamber - we can distinguish two zones with recirculating flows. The first, reaching a distance of about lm from the inlet is characterized by intense mixing of air. A second vortex is formed into a distance greater than lm from the inlet. Such an image of the velocity field results from both the measurements and calculations. Based on this study, we can conclude that the RSM model provides better predictions than the standard k-ɛ model. Good qualitative agreement is achieved between Reynolds Stress model predictions and measured

  10. Sparse Elimination on Vector Multiprocessors.

    DTIC Science & Technology

    2014-09-26

    vector registers . Several reports have been prepared recently under this effort, and a paper entitled "Task Granularity Studies in a Many-Processor Cray X...measures this effect. To reduce this ratio, it has been shown * possible to assembly-code the X-MP so that accesses are pre-fetched into vector registers

  11. GPU Accelerated Vector Median Filter

    NASA Technical Reports Server (NTRS)

    Aras, Rifat; Shen, Yuzhong

    2011-01-01

    Noise reduction is an important step for most image processing tasks. For three channel color images, a widely used technique is vector median filter in which color values of pixels are treated as 3-component vectors. Vector median filters are computationally expensive; for a window size of n x n, each of the n(sup 2) vectors has to be compared with other n(sup 2) - 1 vectors in distances. General purpose computation on graphics processing units (GPUs) is the paradigm of utilizing high-performance many-core GPU architectures for computation tasks that are normally handled by CPUs. In this work. NVIDIA's Compute Unified Device Architecture (CUDA) paradigm is used to accelerate vector median filtering. which has to the best of our knowledge never been done before. The performance of GPU accelerated vector median filter is compared to that of the CPU and MPI-based versions for different image and window sizes, Initial findings of the study showed 100x improvement of performance of vector median filter implementation on GPUs over CPU implementations and further speed-up is expected after more extensive optimizations of the GPU algorithm .

  12. Vectors on the Basketball Court

    ERIC Educational Resources Information Center

    Bergman, Daniel

    2010-01-01

    An Idea Bank published in the April/May 2009 issue of "The Science Teacher" describes an experiential physics lesson on vectors and vector addition (Brown 2009). Like its football predecessor, the basketball-based investigation presented in this Idea Bank addresses National Science Education Standards Content B, Physical Science, 9-12 (NRC 1996)…

  13. Gentle protein ionization assisted by high-velocity gas flow.

    PubMed

    Yang, Pengxiang; Cooks, R Graham; Ouyang, Zheng; Hawkridge, Adam M; Muddiman, David C

    2005-10-01

    Gentle protein electrospray ionization is achieved using the high-velocity gas flow of an air amplifier to improve desolvation in conventional ESI and generate intact folded protein ions in the gas phase. Comparisons are made between the ESI spectra of a number of model proteins, including ubiquitin, cytochrome c, lysozyme, and myoglobin, over a range of pH values under optimized conditions, with and without using an air amplifier to achieve high-velocity gas flow. Previously reported increased ion signals are confirmed. In addition, the peaks recorded using the air amplifier are shown to be narrower, corresponding to more complete desolvation. Significant changes in the charge-state distribution also are observed, with a shift to lower charge state at high-velocity flow. The relationship between the observed charge-state distribution and protein conformation was explored by comparing the charge-state shifts and the distributions of charge states for proteins that are or are not stable in their native conformations in low pH solutions. The data suggest retention of native or nativelike protein conformations using the air amplifier in all cases examined. This is explained by a mechanism in which the air amplifier rapidly creates small droplets from the original large ESI droplets and these microdroplets then desolvate without a significant decrease in pH, resulting in retention of the folded protein conformations. Furthermore, the holoform of ionized myoglobin is visible at pH 3.5, a much lower value than the minimum needed to see this form in conventional ESI. These results provide evidence for the importance of the conditions used in the desolvation process for the preservation of the protein conformation and suggest that the conditions achieved when using high-velocity gas flows to assist droplet evaporation and ion desolvation are much gentler than those in conventional ESI experiments.

  14. On optimal velocity during cycling.

    PubMed

    Maroński, R

    1994-02-01

    This paper focuses on the solution of two problems related to cycling. One is to determine the velocity as a function of distance which minimizes the cyclist's energy expenditure in covering a given distance in a set time. The other is to determine the velocity as a function of the distance which minimizes time for fixed energy expenditure. To solve these problems, an equation of motion for the cyclist riding over arbitrary terrain is written using Newton's second law. This equation is used to evaluate either energy expenditure or time, and the minimization problems are solved using an optimal control formulation in conjunction with the method of Miele [Optimization Techniques with Applications to Aerospace Systems, pp. 69-98 (1962) Academic Press, New York]. Solutions to both optimal control problems are the same. The solutions are illustrated through two examples. In one example where the relative wind velocity is zero, the optimal cruising velocity is constant regardless of terrain. In the second, where the relative wind velocity fluctuates, the optimal cruising velocity varies.

  15. Particle Velocity and Deposition Efficiency in the Cold Spray Process

    SciTech Connect

    Dykhuizen, R.C.; Gilmore, D.L.; Neiser, R.A.; Roemer, T.J.; Smith, M.F.

    1998-11-12

    Copper powder was sprayed by the cold-gas dynamic method. In-flight particle velocities were measured with a laser-two-focus system as a function of process parameters such as gas temperature, gas pressure, and powder feed rate. Particle velocities were uniform in a relatively large volume within the plume and agreed with theoretical predictions. The presence of the substrate was found to have no significant effect on particle velocities. Cold-spray deposition efficiencies were measured on aluminum substrates as a function of particle velocity and incident angle of the plume. Deposition efficiencies of up to 95% were achieved. The critical velocity for deposition was determined to be about 640 meters per second. This work investigates both the in-flight characteristics of copper particles in a supersonic cold-spray plume and the build-up of the subsequent coating on aluminum substrates. Velocities were found to be relatively constant within a large volume of the plume. Particle counts dropped off sharply away from the central axis. The presence of a substrate was found to have no effect on the velocity of the particles. A substantial mass-loading effect on the particle velocity was observed; particle velocities begin to drop as the mass ratio of powder to gas flow rates exceeds 3%. The measured variation of velocity with gas pressure and pre-heat temperature was in fairly good agreement with theoretical predictions. Helium may be used as the driving gas instead of air in order to achieve higher particle velocities for a given temperature and pressure. Coating deposition efficiencies were found to increase with particle velocity and decrease with gun- substrate angle. There did not appear to be any dependence of the deposition efficiency on coating thickness. A critical velocity for deposition of about 640 mk appears to fit the data well. The cold-spray technique shows promise as a method for the deposition of materials which are thermally sensitive or may

  16. Velocity Gradient Maps Directly Measured by PLF

    NASA Astrophysics Data System (ADS)

    Quintella, Cristina M.; Gonçalves, Cristiane C.; Lima, Angelo Mv; Pepe, Iuri M.

    2000-11-01

    Flows are macroscopically classified as laminar or turbulent due to their velocity distributions, nevertheless most chemical and biological phenomena are yield or enhanced by intermolecular orientation and microscopic turbulence. Here was studied a 100micra liquid sheet produced by a slit nozzle, both flowing freely into air and over a borosilicate surface (roughness bellow 5nm), ranging from 17 to 36Re (143 to 297cm/s, similar to muscles and brain blood flow). Mono ethylene glycol was used either pure, or with sodium alkyl benzene sulfated (ABS) surfactant (24.5mol/L, submicellar), or with poly(ethylene oxide) (PEO) (1409ppm, 4millions aw). Velocity gradients were directly measured by 514nm polarized laser induced fluorescence (PLF) with R6G as probe. Intermolecular alignment (IA) maps were obtained all over the flow (about 1,950 points, 0.02mm2 precision). The free jet average IA has increased 57% when flowing over borosilicate. With ABS, the IA increased, suggesting wall drag reduction. With PEO the IA decreases due to solvent intermolecular forces attenuation, generating wider turbulent areas. PLF proved to be an excellent method to evaluate IA within liquid thin flows. Chosen solute additions permits IA control over wide regions.

  17. Global GPS Solution for Station Velocities Without Conventional Reference Frame

    NASA Astrophysics Data System (ADS)

    Kogan, M. G.; Steblov, G. M.

    2005-12-01

    Meaningful GPS station velocities should not depend on the choice of a specific reference frame since the origin translation rate (OTR) can be estimated from velocities in stable plate interiors, and an appropriate correction can be applied (R.W. King, private communication). A conventional approach is to translate and rotate the initial, loosely constrained geodetic solution in order to best fit the velocities of official ITRF2000. A very different approach used in this study consists of following steps: (1) Assume that tectonic plates do not move with respect to each other and that they are perfectly rigid. This assumption is equivalent to setting all a priori velocities to zero. (2) Translate and rotate the loose geodetic solution to best fit the zero velocities at stations uniformly distributed over the whole network. (3) Evaluate OTR from station velocities in stable plate interiors, obtained in step 2. (4) Correct the velocities for OTR and estimate plate rotation vectors. (5) Repeat steps 1-4 as many times as required, typically four iterations is adequate. Such approach was realized in recent versions of the GAMIT/GLOBK software which we used. We tested at step 1 various starting reference frames with nonzero a priori velocities, such as ITRF2000 and NUVEL1-A, with no change in the final solution at step 5. Our database included: all daily GAMIT solutions for positions of the IGS network performed at SOPAC in interval 1995.0 - 2005.5; our daily GAMIT solutions from observations of several tens of continuous and survey mode stations on the Eurasian, North American, and Pacific plates. We then combined by GLOBK (Kalman filter) all daily solutions in the database and produced a multiyear loose solution for positions and velocities. By iteratively applying procedure 1-5, we came to the constrained solution in terms of plate-residual velocities for all stations and a set of rotation vectors for eight major plates. 76 sites with zero velocity chosen for initial

  18. Calibration of Instruments for Measuring Wind Velocity and Direction

    NASA Technical Reports Server (NTRS)

    Vogler, Raymond D.; Pilny, Miroslav J.

    1950-01-01

    Signal Corps wind equipment AN/GMQ-1 consisting of a 3-cup anemometer and wind vane was calibrated for wind velocities from 1 to 200 miles per hour. Cup-shaft failure prevented calibration at higher wind velocities. The action of the wind vane was checked and found to have very poor directional accuracy below a velocity of 8 miles per hour. After shaft failure was reported to the Signal Corps, the cup rotors were redesigned by strengthening the shafts for better operation at high velocities. The anemometer with the redesigned cup rotors was recalibrated, but cup-shaft failure occurred again at a wind velocity of approximately 220 miles per hour. In the course of this calibration two standard generators were checked for signal output variation, and a wind-speed meter was calibrated for use with each of the redesigned cup rotors. The variation of pressure coefficient with air-flow direction at four orifices on a disk-shaped pitot head was obtained for wind velocities of 37.79 53.6, and 98.9 miles per hour. A pitot-static tube mounted in the nose of a vane was calibrated up to a dynamic pressure of 155 pounds per square foot, or approximately 256 miles per hour,

  19. Coherent Doppler Lidar for Measuring Velocity and Altitude of Space and Arial Vehicles

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Pierrottet, Diego; Hines, Glenn D.; Petway, Larry; Barnes, Bruce W.

    2016-01-01

    A coherent Doppler lidar has been developed to support future NASA missions to planetary bodies. The lidar transmits three laser beams and measures line-of-sight range and velocity along each beam using a frequency modulated continuous wave (FMCW) technique. Accurate altitude and velocity vector data, derived from the line-of-sight measurements, enables the landing vehicle to precisely navigate from several kilometers above the ground to the designated location and execute a gentle touchdown. The same lidar sensor can also benefit terrestrial applications that cannot rely on GPS or require surface-relative altitude and velocity data.

  20. Contribution from cosmological scalar perturbations to the angular velocity spectrum of extragalactic sources

    SciTech Connect

    Marakulin, A. O. Sazhina, O. S.; Sazhin, M. V.

    2012-07-15

    The possibility of the influence of adiabatic scalar perturbations on the angular velocity spectrum of extragalactic sources is considered. The multipole expansion coefficients of the angular velocity field in terms of vector spherical harmonics are calculated. We show that there is no contribution from adiabatic perturbations to the angular spectrum for a spatially flat Universe at the dusty stage, while there is a contribution only to the electric multiple coefficients at the stage of {Lambda}-term domination. The cases of long-wavelength and short-wavelength perturbations are considered separately. The relationship between the multipole angular velocity spectrum and the primordial scalar perturbation spectrum is discussed.

  1. Chikungunya Virus–Vector Interactions

    PubMed Central

    Coffey, Lark L.; Failloux, Anna-Bella; Weaver, Scott C.

    2014-01-01

    Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes chikungunya fever, a severe, debilitating disease that often produces chronic arthralgia. Since 2004, CHIKV has emerged in Africa, Indian Ocean islands, Asia, Europe, and the Americas, causing millions of human infections. Central to understanding CHIKV emergence is knowledge of the natural ecology of transmission and vector infection dynamics. This review presents current understanding of CHIKV infection dynamics in mosquito vectors and its relationship to human disease emergence. The following topics are reviewed: CHIKV infection and vector life history traits including transmission cycles, genetic origins, distribution, emergence and spread, dispersal, vector competence, vector immunity and microbial interactions, and co-infection by CHIKV and other arboviruses. The genetics of vector susceptibility and host range changes, population heterogeneity and selection for the fittest viral genomes, dual host cycling and its impact on CHIKV adaptation, viral bottlenecks and intrahost diversity, and adaptive constraints on CHIKV evolution are also discussed. The potential for CHIKV re-emergence and expansion into new areas and prospects for prevention via vector control are also briefly reviewed. PMID:25421891

  2. Vector fields in multidimensional cosmology

    NASA Astrophysics Data System (ADS)

    Meierovich, Boris E.

    2011-09-01

    Vector fields in the expanding Universe are considered within the multidimensional theory of general relativity. Vector fields in general relativity form a three-parametric variety. Our consideration includes the fields with a nonzero covariant divergence. Depending on the relations between the particular parameters and the symmetry of a problem, the vector fields can be longitudinal and/or transverse, ultrarelativistic (i.e. massless) or nonrelativistic (massive), and so on. The longitudinal and transverse vector fields are considered separately in detail in the background of the de Sitter cosmological metric. In most cases the field equations reduce to Bessel equations, and their temporal evolution is analyzed analytically. The energy-momentum tensor of the most simple zero-mass longitudinal vector fields enters the Einstein equations as an additive to the cosmological constant. In this case the de Sitter metric is the exact solution of the Einstein equations. Hence, the most simple zero-mass longitudinal vector field pretends to be an adequate tool for macroscopic description of dark energy as a source of the expansion of the Universe at a constant rate. The zero-mass vector field does not vanish in the process of expansion. On the contrary, massive fields vanish with time. Though their amplitude is falling down, the massive fields make the expansion accelerated.

  3. Design of a Non-scanning Lidar for Wind Velocity and Direction Measurement

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Peng, Zhangxian

    2016-06-01

    A Doppler lidar system for wind velocity and direction measurement is presented. The lidar use a wide field of view (FOV) objective lens as an optical antenna for both beam transmitting and signal receiving. By four fibers coupled on different position on the focal plane, the lidar can implement wind vector measurement without any scanning movement.

  4. Cause and solution for false upstream boat velocities measured with a StreamPro acoustic doppler current profiler

    USGS Publications Warehouse

    Mueller, David S.; Rehmel, Mike S.; Wagner, Chad R.

    2007-01-01

    In 2003, Teledyne RD Instruments introduced the StreamPro acoustic Doppler current profiler which does not include an internal compass. During stationary moving-bed tests the StreamPro often tends to swim or kite from the end of the tether (the instrument rotates then moves laterally in the direction of the rotation). Because the StreamPro does not have an internal compass, it cannot account for the rotation. This rotation and lateral movement of the StreamPro on the end of the tether generates a false upstream velocity, which cannot be easily distinguished from a moving-bed bias velocity. A field test was completed to demonstrate that this rotation and lateral movement causes a false upstream boat velocity. The vector dot product of the boat velocity and the unit vector of the depth-averaged water velocity is shown to be an effective method to account for the effect of the rotation and lateral movement.

  5. The diffusion of radiation in moving media. IV. Flux vector, effective opacity, and expansion opacity

    NASA Astrophysics Data System (ADS)

    Wehrse, R.; Baschek, B.; von Waldenfels, W.

    2003-04-01

    For a given velocity and temperature field in a differentially moving 3D medium, the vector of the radiative flux is derived in the diffusion approximation. Due to the dependence of the velocity gradient on the direction, the associated effective opacity in general is a tensor. In the limit of small velocity gradients analytical expression are obtained which allow us to discuss the cases when the direction of the flux vector deviates from that of the temperature gradient. Furthermore the radiative flux is calculated for infinitely sharp, Poisson distributed spectral lines resulting in simple expressions that provide basic insight into the effect of the motions. In particular, it is shown how incomplete line lists affect the radiative flux as a function of the velocity gradient. Finally, the connection between our formalism and the concept of the expansion opacity introduced by Karp et al. (\\cite{karp}) is discussed.

  6. Calibration method helps in seismic velocity interpretation

    SciTech Connect

    Guzman, C.E.; Davenport, H.A.; Wilhelm, R.

    1997-11-03

    Acoustic velocities derived from seismic reflection data, when properly calibrated to subsurface measurements, help interpreters make pure velocity predictions. A method of calibrating seismic to measured velocities has improved interpretation of subsurface features in the Gulf of Mexico. In this method, the interpreter in essence creates a kind of gauge. Properly calibrated, the gauge enables the interpreter to match predicted velocities to velocities measured at wells. Slow-velocity zones are of special interest because they sometimes appear near hydrocarbon accumulations. Changes in velocity vary in strength with location; the structural picture is hidden unless the variations are accounted for by mapping in depth instead of time. Preliminary observations suggest that the presence of hydrocarbons alters the lithology in the neighborhood of the trap; this hydrocarbon effect may be reflected in the rock velocity. The effect indicates a direct use of seismic velocity in exploration. This article uses the terms seismic velocity and seismic stacking velocity interchangeably. It uses ground velocity, checkshot average velocity, and well velocity interchangeably. Interval velocities are derived from seismic stacking velocities or well average velocities; they refer to velocities of subsurface intervals or zones. Interval travel time (ITT) is the reciprocal of interval velocity in microseconds per foot.

  7. Gas-rise velocities during kicks

    SciTech Connect

    White, D.B. )

    1991-12-01

    This paper reports on experiments to examine gas migration rates in drilling muds that were performed in a 15-m-long, 200-mm-ID inclinable flow loop where air injection simulates gas entry during a kick. These tests were conducted using a xanthum gum (a common polymer used in drilling fluids) solution to simulate drilling muds as the liquid phase and air as the gas phase. This work represents a significant extension of existing correlations for gas/liquid flows in large pipe diameters with non- Newtonian fluids. Bubbles rise faster in drilling muds than in water despite the increased viscosity. This surprising result is caused by the change in the flow regime, with large slug-type bubbles forming at lower void fractions. The gas velocity is independent of void fraction, thus simplifying flow modeling. Results show that a gas influx will rise faster in a well than previously believed. This has major implications for kick simulation, with gas arriving at the surface earlier than would be expected and the gas outflow rate being higher than would have been predicted. A model of the two-phase gas flow in drilling mud, including the results of this work, has been incorporated into the joint Schlumberger Cambridge Research (SCR)/BP Intl. kick model.

  8. Modeling and performance analysis of GPS vector tracking algorithms

    NASA Astrophysics Data System (ADS)

    Lashley, Matthew

    This dissertation provides a detailed analysis of GPS vector tracking algorithms and the advantages they have over traditional receiver architectures. Standard GPS receivers use a decentralized architecture that separates the tasks of signal tracking and position/velocity estimation. Vector tracking algorithms combine the two tasks into a single algorithm. The signals from the various satellites are processed collectively through a Kalman filter. The advantages of vector tracking over traditional, scalar tracking methods are thoroughly investigated. A method for making a valid comparison between vector and scalar tracking loops is developed. This technique avoids the ambiguities encountered when attempting to make a valid comparison between tracking loops (which are characterized by noise bandwidths and loop order) and the Kalman filters (which are characterized by process and measurement noise covariance matrices) that are used by vector tracking algorithms. The improvement in performance offered by vector tracking is calculated in multiple different scenarios. Rule of thumb analysis techniques for scalar Frequency Lock Loops (FLL) are extended to the vector tracking case. The analysis tools provide a simple method for analyzing the performance of vector tracking loops. The analysis tools are verified using Monte Carlo simulations. Monte Carlo simulations are also used to study the effects of carrier to noise power density (C/N0) ratio estimation and the advantage offered by vector tracking over scalar tracking. The improvement from vector tracking ranges from 2.4 to 6.2 dB in various scenarios. The difference in the performance of the three vector tracking architectures is analyzed. The effects of using a federated architecture with and without information sharing between the receiver's channels are studied. A combination of covariance analysis and Monte Carlo simulation is used to analyze the performance of the three algorithms. The federated algorithm without

  9. Insecticide resistance and vector control.

    PubMed Central

    Brogdon, W. G.; McAllister, J. C.

    1998-01-01

    Insecticide resistance has been a problem in all insect groups that serve as vectors of emerging diseases. Although mechanisms by which insecticides become less effective are similar across all vector taxa, each resistance problem is potentially unique and may involve a complex pattern of resistance foci. The main defense against resistance is close surveillance of the susceptibility of vector populations. We describe the mechanisms of insecticide resistance, as well as specific instances of resistance emergence worldwide, and discuss prospects for resistance management and priorities for detection and surveillance. PMID:9866736

  10. Vector statistics of LANDSAT imagery

    NASA Technical Reports Server (NTRS)

    Jayroe, R. R., Jr.; Underwood, D.

    1977-01-01

    A digitized multispectral image, such as LANDSAT data, is composed of numerous four dimensional vectors, which quantitatively describe the ground scene from which the data are acquired. The statistics of unique vectors that occur in LANDSAT imagery are studied to determine if that information can provide some guidance on reducing image processing costs. A second purpose of this report is to investigate how the vector statistics are changed by various types of image processing techniques and determine if that information can be useful in choosing one processing approach over another.

  11. Linear Motor With Air Slide

    NASA Technical Reports Server (NTRS)

    Johnson, Bruce G.; Gerver, Michael J.; Hawkey, Timothy J.; Fenn, Ralph C.

    1993-01-01

    Improved linear actuator comprises air slide and linear electric motor. Unit exhibits low friction, low backlash, and more nearly even acceleration. Used in machinery in which positions, velocities, and accelerations must be carefully controlled and/or vibrations must be suppressed.

  12. Geostatistical Modeling of Pore Velocity

    SciTech Connect

    Devary, J.L.; Doctor, P.G.

    1981-06-01

    A significant part of evaluating a geologic formation as a nuclear waste repository involves the modeling of contaminant transport in the surrounding media in the event the repository is breached. The commonly used contaminant transport models are deterministic. However, the spatial variability of hydrologic field parameters introduces uncertainties into contaminant transport predictions. This paper discusses the application of geostatistical techniques to the modeling of spatially varying hydrologic field parameters required as input to contaminant transport analyses. Kriging estimation techniques were applied to Hanford Reservation field data to calculate hydraulic conductivity and the ground-water potential gradients. These quantities were statistically combined to estimate the groundwater pore velocity and to characterize the pore velocity estimation error. Combining geostatistical modeling techniques with product error propagation techniques results in an effective stochastic characterization of groundwater pore velocity, a hydrologic parameter required for contaminant transport analyses.

  13. Signal velocity in oscillator arrays

    NASA Astrophysics Data System (ADS)

    Cantos, C. E.; Veerman, J. J. P.; Hammond, D. K.

    2016-09-01

    We investigate a system of coupled oscillators on the circle, which arises from a simple model for behavior of large numbers of autonomous vehicles where the acceleration of each vehicle depends on the relative positions and velocities between itself and a set of local neighbors. After describing necessary and sufficient conditions for asymptotic stability, we derive expressions for the phase velocity of propagation of disturbances in velocity through this system. We show that the high frequencies exhibit damping, which implies existence of well-defined signal velocitiesc+ > 0 and c- < 0 such that low frequency disturbances travel through the flock as f+(x - c+t) in the direction of increasing agent numbers and f-(x - c-t) in the other.

  14. Are Bred Vectors The Same As Lyapunov Vectors?

    NASA Astrophysics Data System (ADS)

    Kalnay, E.; Corazza, M.; Cai, M.

    Regional loss of predictability is an indication of the instability of the underlying flow, where small errors in the initial conditions (or imperfections in the model) grow to large amplitudes in finite times. The stability properties of evolving flows have been studied using Lyapunov vectors (e.g., Alligood et al, 1996, Ott, 1993, Kalnay, 2002), singular vectors (e.g., Lorenz, 1965, Farrell, 1988, Molteni and Palmer, 1993), and, more recently, with bred vectors (e.g., Szunyogh et al, 1997, Cai et al, 2001). Bred vectors (BVs) are, by construction, closely related to Lyapunov vectors (LVs). In fact, after an infinitely long breeding time, and with the use of infinitesimal ampli- tudes, bred vectors are identical to leading Lyapunov vectors. In practical applications, however, bred vectors are different from Lyapunov vectors in two important ways: a) bred vectors are never globally orthogonalized and are intrinsically local in space and time, and b) they are finite-amplitude, finite-time vectors. These two differences are very significant in a dynamical system whose size is very large. For example, the at- mosphere is large enough to have "room" for several synoptic scale instabilities (e.g., storms) to develop independently in different regions (say, North America and Aus- tralia), and it is complex enough to have several different possible types of instabilities (such as barotropic, baroclinic, convective, and even Brownian motion). Bred vectors share some of their properties with leading LVs (Corazza et al, 2001a, 2001b, Toth and Kalnay, 1993, 1997, Cai et al, 2001). For example, 1) Bred vectors are independent of the norm used to define the size of the perturba- tion. Corazza et al. (2001) showed that bred vectors obtained using a potential enstro- phy norm were indistinguishable from bred vectors obtained using a streamfunction squared norm, in contrast with singular vectors. 2) Bred vectors are independent of the length of the rescaling period as long as the

  15. Vector independent transmission of the vector-borne bluetongue virus.

    PubMed

    van der Sluijs, Mirjam Tineke Willemijn; de Smit, Abraham J; Moormann, Rob J M

    2016-01-01

    Bluetongue is an economically important disease of ruminants. The causative agent, Bluetongue virus (BTV), is mainly transmitted by insect vectors. This review focuses on vector-free BTV transmission, and its epizootic and economic consequences. Vector-free transmission can either be vertical, from dam to fetus, or horizontal via direct contract. For several BTV-serotypes, vertical (transplacental) transmission has been described, resulting in severe congenital malformations. Transplacental transmission had been mainly associated with live vaccine strains. Yet, the European BTV-8 strain demonstrated a high incidence of transplacental transmission in natural circumstances. The relevance of transplacental transmission for the epizootiology is considered limited, especially in enzootic areas. However, transplacental transmission can have a substantial economic impact due to the loss of progeny. Inactivated vaccines have demonstrated to prevent transplacental transmission. Vector-free horizontal transmission has also been demonstrated. Since direct horizontal transmission requires close contact of animals, it is considered only relevant for within-farm spreading of BTV. The genetic determinants which enable vector-free transmission are present in virus strains circulating in the field. More research into the genetic changes which enable vector-free transmission is essential to better evaluate the risks associated with outbreaks of new BTV serotypes and to design more appropriate control measures.

  16. Biomass torrefaction characteristics in inert and oxidative atmospheres at various superficial velocities.

    PubMed

    Chen, Wei-Hsin; Lu, Ke-Miao; Liu, Shih-Hsien; Tsai, Chi-Ming; Lee, Wen-Jhy; Lin, Ta-Chang

    2013-10-01

    The reaction characteristics of four biomass materials (i.e. oil palm fiber, coconut fiber, eucalyptus, and Cryptomeria japonica) with non-oxidative and oxidative torrefaction at various superficial velocities are investigated where nitrogen and air are used as carrier gases. Three torrefaction temperatures of 250, 300, and 350 °C are considered. At a given temperature, the solid yield of biomass is not affected by N2 superficial velocity, revealing that the thermal degradation is controlled by heat and mass transfer in biomass. Increasing air superficial velocity decreases the solid yield, especially in oil palm fiber and coconut fiber, implying that the torrefaction reaction of biomass is dominated by surface oxidation. There exists an upper limit of air superficial velocity in the decrement of solid yield, suggesting that beyond this limit the thermal degradation of biomass is no longer governed by surface oxidation, but rather is controlled by internal mass transport.

  17. Interferometer for Low-Uncertainty Vector Metrology

    NASA Technical Reports Server (NTRS)

    Toland, Ronald W.; Leviton, Douglas B.

    2006-01-01

    A simplified schematic diagram of a tilt-sensing unequal-path interferometer set up to measure the orientation of the normal vector of one surface of a cube mounted on a structure under test is described herein. This interferometer has been named a "theoferometer" to express both its interferometric nature and the intention to use it instead of an autocollimating theodolite. The theoferometer optics are mounted on a plate, which is in turn mounted on orthogonal air bearings for near-360 rotation in azimuth and elevation. Rough alignment of the theoferometer to the test cube is done by hand, with fine position adjustment provided by a tangent arm drive using linear inchwormlike motors.

  18. Noise Prevents Infinite Stretching of the Passive Field in a Stochastic Vector Advection Equation

    NASA Astrophysics Data System (ADS)

    Flandoli, Franco; Maurelli, Mario; Neklyudov, Mikhail

    2014-09-01

    A linear stochastic vector advection equation is considered; the equation may model a passive magnetic field in a random fluid. When the driving velocity field is rough but deterministic, in particular just Hölder continuous and bounded, one can construct examples of infinite stretching of the passive field, arising from smooth initial conditions. The purpose of the paper is to prove that infinite stretching is prevented if the driving velocity field contains in addition a white noise component.

  19. Velocity measurements in a boundary layer with a density gradient

    SciTech Connect

    Neuwald, P.; Reichenbach, H.; Kuhl, A.L.

    1992-11-01

    A number of experiments were performed at the EMI shock tube facility on shock waves propagating in a stratified atmosphere with density gradient modelled by air layered above Freon (C Cl{sub 2} F{sub 2}). This report presents streamwise velocity data for the flow behind the shock front. Additional information from measurements of overpressure history and shadowgraphs of the flow will be presented in a future EMI-report.

  20. Integrated Thrust Vectored Engine Control

    DTIC Science & Technology

    2001-06-01

    erformances operationnelles des aeronefs militaires, des vehicules terrestres et des vehicules maritimes] To order the complete compilation report...throttling "* Autonomous Engine Configuration Side forces demand to define nozzle vectoring "* Simple Interface FADEC -> FCS " Minimum Interaction FCS